Basic concept

Significant technological advances, which sustainably strengthen Germany as a business location, are increasingly being realised through new materials and optimised technologies. In the area of conflict between the conservation of resources and increased productivity, material developments through innovative manufacturing processes are becoming increasingly important. The overriding goal of our research group is the use of high pressures for material development, the optimisation and characterisation of properties and the transfer of the knowledge gained into marketable products. Our vision is the production of extremely hard materials. Compared to diamond, these materials should be cheaper to produce and have higher temperature and corrosion resistance.

An application-related example is the as yet unsuccessful synthesis of cutting materials for drill bits in deep drilling technology in hard rock or in tools for the extraction of raw materials. A significantly improved service life could bring considerable progress in geothermal energy, a key technology for the sustainable utilisation of energy. Composite materials could also open up completely new areas of application or lead to significant increases in performance in existing technologies such as turbine construction. Another example is the development of hard materials for high-speed machining in mechanical engineering.

The aim of our research group is to utilise pressure to develop materials. To this end, existing expertise in the fields

• of high-pressure synthesis (TP 2: Multi-Anvil Synthesis, TP 3: Shockwave Synthesis)
• the test under extreme loads, such as pressure, temperature, speed (TP 6: Material behaviour)
• of microstructure characterisation and modelling (TP 1: Structure predictions, TP 7: Structure-Property),
• shock loading (TP 3: Shock wave synthesis)
• the modelling of material formation processes (TP 8: Spark Plasma Sintering)
• and application-oriented research (TP 4: Rock destruction, TP 5: Prototype tool)

will be bundled across faculties. New high-performance materials are to be developed using very different but complementary high-pressure synthesis techniques. The materials and conditions in focus should deliberately correspond to the fields of technology and geosciences.

Patents

The Freiberg High Pressure Research Centre presents the results it has achieved at various international and national levels. In addition to registered and granted patents, a number of interesting publications have been published in international scientific journals. Contributions at international conferences also contribute to the external presentation of the FHP.

granted

• Schwarz, M.; Mertens, F.; Kirsten, U.; Röntzsch, S. & Reich, M.: "Meißeldirektantrieb für Werkzeuge auf Basis einer Wärmekraftmaschine" DE 102010 050 244.
• Keller, K., Schlothauer, T., Schwarz, M., Heide, G. and Kroke, E. "Process for the production of aluminium nitride with common salt structure by shock wave synthesis". German. Patent application 102011051647.6

applied for

• M. Schwarz, E. Kroke, J. Kortus, C. Loose, Hard and incompressible solid-state compounds based on the elements silicon, aluminium and nitrogen, process for their production and use, filing date: 06.02.2009, file number: 10 2009 007 749.9.
• Schwarz, M.; Mertens, F.; Kirsten, U.; Röntzsch, S. & Reich, M."Direct drill bit drive for tools on the basis of a heat engine" German patent application DE 102010 050 244.
• Invention report no. 25/12 "LCM data pulser" DE - 10 2012 105 273.5 "Pressure wave generators and method for controlling a pressure wave generator"
• Schwarz, M.; Kirsten, U.; Reich, M.; Röntzsch, S.; Mertens, F., "Direct drill bit drive for tools on the basis of a heat engine", WO 2012/055392.
• Schwarz, M.; Kirsten, U.; Reich, M.; Röntzsch, S.; Mertens, F., "Direct drill bit drive for tools on the basis of a heat engine", EP000002633147A2
• Schwarz, M.; Kirsten, U.; Reich, M.; Röntzsch, S.; Mertens, F., "Direct drill bit drive for tools on the basis of a heat engine", US020130220656A1
• Schwarz, M.; Kirsten, U.; Reich, M.; Röntzsch, S.; Mertens, F., "Direct drill bit drive for tools on the basis of a heat engine", AU002011320466A1
• Schwarz, M.; Kirsten, U.; Reich, M.; Röntzsch, S.; Mertens, F., "Direct drill bit drive for tools on the basis of a heat engine", CA000002816470A1

Publications

2013

C. Loose, J. Kortus: Systematic study of the influence of different equations of states on the calculation of elastic properties, High Pressure Research 33 (2013), 622
DOI 10.1080/08957959.2013.806657

S. Bahmann, T. Weißbach, J. Kortus, Crossed graphene: Stability and electronic structure, Rapid Res. Lett. Phys. Stat. Sol. 7 (2013) 639
DOI 10.1002/pssr.201307226

M. F. Bekheet, M.R. Schwarz, S. Lauterbach, H.-J. Kleebe, P. Kroll, R.Riedel, Orthorhombic In₂O₃ - a metastable indium sesquioxide polymorph, Angew. Chem. 125 (2013) 1
DOI 10.1002/ange.201300644

C. Schimpf, M. Motylenko, D. Rafaja, Quantitative description of microstructure defects in hexagonal boron nitrides using X-ray diffraction analysis, Materials Characterisation 86 (2013) 190
DOI 10.1016/j.matchar.2013.09.011

M.F. Bekheet, M.R. Schwarz, M.M. Müller, S. Lauterbach, H.-J. Kleebe, R. Riedel, A. Gurlo, Phase segregation in Mn-doped In₂O₃: in situ high pressure hightemperature synchrotron studies in multi-anvil assemblies, RSC Advances 3 (2013) 5357
DOI 10.1039/C3RA22998J

S. Bahmann, J. Kortus, EVO - Evolutionary algorithm for crystal structure prediction, Computer Physics Communications 184 (2013) 1618
DOI 10.1016/j.cpc.2013.02.007

M.F. Bekheet, M. Schwarz, S. Lauterbach, H.-J. Kleebe, P. Kroll, A. Stewart, U. Kolb, R.; Riedel, A. Gurlo, In situ high pressure high temperature experiments in multi-anvil assemblies with bixbyite-type In2O3 and synthesis of corundum-type and orthorhombic In₂O₃ polymorphs, High Pressure Research (2013)
DOI 10.1080/08957959.2013.834896

2012

K. Keller, T. Schlothauer, M. Schwarz, G. Heide and E. Kroke, Shock wave synthesis of aluminium nitride with rocksalt structure, High Pressure Res. 32 (2012) 23
DOI 10.1080/08957959.2011.642990

D. Rafaja, C. Wüstefeld, M. Motylenko, C. Schimpf, T. Barsukova, M.R. Schwarz, E. Kroke, Interface phenomena in (super)hard nitride nanocomposites: from coatings to bulk materials, Chemical Society Reviews 41 (2012) 5081
DOI 10.1039/C2CS15351C

M. Dopita, A. Salomon, D. Chmelik, B. Reichelt, D. Rafaja: Field assisted sintering technique compaction of ultrafine-Grained binderless WC Hard Metals, Acta Physica Polonica A 122 (2012) 639

T. Schlothauer, K. Keller A. Greif, M. R. Schwarz, E. Kroke, G. Heide, The new subterranean shock-wave-laboratory at the TU Bergakademie Freiberg/ Germany, in Final Report of the XI International Symposium on Explosive Production of New Materials: Science, Technology, Business, and Innovations (EPNM-2012), held May 2-5, 2012 in Strasbourg, France, XI EPNM 2012, pp. 105-107.

S.B. Schneider, D. Baumann, A. Salamat, Z. Konôpková, H.-P. Liermann, M.R. Schwarz, W. Morgenroth, L. Bayarjargal, A. Friedrich, B. Winkler, W. Schnick, Materials Properties of Ultra-Incompressible Re2P, Chemistry of Materials 24 (2012) 3240
DOI 10.1021/cm3016885

K. Keller, T. Schlothauer, M. Schwarz, E. Brendler, K. Galonska, G. Heide, and E. Kroke, Properties of shock-synthesized rocksalt-aluminium nitride, Processing and Properties of Advanced Ceramics and Composites IV: Ceramic Transactions 234 (2012) 305
DOI 10.1002/9781118491867.ch31

T. Schlothauer, M. R. Schwarz, M. Ovidiu, E. Brendler, R. Moeckel, E. Kroke, and G. Heide, "Shock Wave" Synthesis of Oxygen-Bearing Spinel-Type Silicon Nitride γ-Si3(O,N)4 in the Pressure Range from 30 to 72 GPa with High Purity, Minerals as Advanced Materials II (2012) 375
DOI 10.1007/978-3-642-20018-2_35

C. Schimpf, M. Schwarz, E. Kroke, C. Lathe, D. Rafaja, Significance of microstructure defects for the high pressure/high temperature phase transitions in BN, HASYLAB Annual Report 2012

2011

M. Dopita, D. Rafaja, D. Chmelik, A. Salomon, D. Janisch and W. Lengauer, Microstructural Investigation of Hard Metals by Combination of Electron Backscatter Diffraction and X-Ray Diffraction, Materials Structure 18 (2011) 169

2010

U. Kirsten, M. Reich: Chipping rock destruction with defined cutting edges, bbr - Fachmagazin für Brunnen- und Leitungsbau, Ausgabe 12/2010, 61. Jahrgang, S. 34-41, Bonn, wvgw Wirtschafts- und Verlagsgesellschaft Gas und Wasser mbH

R. Kužel, M. Janeček, Z. Matěj, J. Čížek, M. Dopita, O. Srba: Microstructure of ECAP Cu and Cu-Zr samples studied by different methods, Metallurgical and Materials Transactions A 41 (2010) 1174
DOI 10.1007/s11661-009-9895-0

K. Niemietz, A. Wagner, B. Gründig-Wendrock, D. Stoyan, J. R. Niklas, Variogram analysis of charge-carrier effective lifetime topograms in mc-Si materials, Solar Energy Materials & Solar Cells 94 (2010) 164
DOI 10.1016/j.solmat.2009.08.016

M. R. Schwarz, Multianvil calibration and education: A four probe method to measure the entire force-versus-pressure curve in a single run - performed as an interdisciplinary lab-course for students, Journal of Physics: Conference Series 215 (2010) 012193
DOI 10.1088/1742-6596/215/1/012193

A. Wagner, M. Hütter, D. Stoyan, More on the microstructural characterisation of dense particle gels, J. Eur. Cer. Soc. 30 (2010) 1237
DOI 10.1016/j.jeurceramsoc.2009.10.004

2009

Z. Matěj, R. Kužel, M. Dopita, M. Janeček, J. Čížek, T. Brunátová: XRD profile analysis of ECAP Cu and Cu+Zr samples, Int. J. Mat. Res. 100 (2009) 880
DOI 10.3139/146.110112

C. Schimpf, T. Barsukova, M. Schwarz, D. Simek, C. Lathe, D. Rafaja, E. Kroke, In-situ synchrotron radiation study of bulk BN nanocomposites during high pressure - high temperature conversion at MAX200x using improved pressure cell design, HASYLAB Annual Report 2009

K. Máthis, T. Krajňák, M. Janeček, M. Dopita, H.S. Kim, Microstructural evolution of equal channel angular pressed IF steel, Int. J. Mat. Res. 100 (2009) 834
DOI 10.3139/146.110100

M. Dopita, M. Janeček, D. Rafaja, J. Uhlíř, Z. Matěj, R. Kužel: EBSD investigation of the grain boundary distributions in the ultrafine-grained Cu and Cu-Zr polycrystals prepared by equal-channel angular pressing, Int. J. Mat. Res. 100 (2009) 785
DOI 10.3139/146.110111

D. Rafaja, Edwin Kroke: Nützliche Defekte, Zeitschrift für Freunde und Förderer der TU Bergakademie Freiberg (2009) 39

A. Elsner, A. Wagner, T. Aste, H. Hermann, D. Stoyan, Specific Surface Area and Volume Fraction of the Cherry-Pit Model with Packed Pits, J. Phys. Chem. B 113 (2009) 7780
DOI 10.1021/jp806767m

M. Dopita, D. Rafaja, H.J. Seifert, D. Janisch, W. Lengauer: Capability of the combination of electron backscatter diffraction and X-ray diffraction for the structural investigation of hardmetals, Proceedings of the 17th Plansee Seminar, Plansee Reutte (2009), AT 4/1-13.

A. Prescimone, C. J. Milios, J. Sanchez-Benitez, K. Kamenev, C. Loose, J. Kortus, S. Moggach, M. Murrie, J. E. Warren, A. R. Lennie, S. Parsons, E. K. Brechin, High pressure induced spin changes and magneto-structural coorelations in hexametallic SMMs; Dalton Trans. 25 (2009) 4817
DOI 10.1039/B902485A

2008

D. Rafaja, V. Klemm, Ch. Wüstefeld, M. Motylenko, M. Dopita, M. Schwarz, T. Barsukova, E. Kroke: Interference phenomena in nanocrystalline materials and their application in the microstructure analysis, Z. Kristallogr. Suppl. 27 (2008) 15

D. Rafaja, V. Klemm, M. Motylenko, M. R. Schwarz, T. Barsukova, E. Kroke, D.Frost, L. Dubrovinsky, N. Dubrovinskaia: Synthesis, microstructure and hardness of bulk ultrahard BN nanocomposites, Journal of Materials Research 23 (2008) 981
DOI 10.1557/jmr.2008.0117

M. Dopita, Ch. Wüstefeld, V. Klemm, G. Schreiber, D. Heger, M. Růžička, D. Rafaja, Residual stress and elastic anisotropy in the Ti-Al-(Si-)N and Cr-Al-(Si-)N nanocomposites deposited by cathodic arc evaporation, Zeitschrift für Kristallographie Suppl. 27 (2008) 245

M. Dopita, D. Rafaja, Ch. Wüstefeld, M. Růžička, V. Klemm, D. Heger, G. Schreiber, M. Šíma, Interplay of microstructural features in Cr1-xAlxN and Cr1-x-yAlxSiyN nanocomposite coatings deposited by cathodic arc evaporation, Surface and Coatings Technology 202 (2008) 3199
DOI 10.1016/j.surfcoat.2007.11.027

M. Motylenko, V. Klemm, G. Schreiber, D. Rafaja, M. Schwarz, T. Barsukova, E. Kroke, XRD and HRTEM study of coherence phenomena in ultra-hard BN nanocomposites, Z. Kristallogr. Suppl. 27 (2008) 45

D. Rafaja, M. Dopita, M. Masimov, V. Klemm, N. Wendt, W. Lengauer: Analysis of local composition gradients in the hard-phase grains of cermets using a combination of X-ray diffraction and electron microscopy, International Journal of Refractory Metals and Hard Materials 26 (2008) 263
DOI 10.1016/j.ijrmhm.2007.03.004

2007

D. Rafaja, V. Klemm, M. Dopita: Practical aspects of partial coherence of nanocrystalline domains, Newsletter of the Commission on Powder Diffraction 34 (2007) 7

D. Rafaja, V. Klemm, C. Wüstefeld, M. Motylenko, M. Dopita, Microstructure analysis of nanocrystalline materials and nanocomposites using the combination of X-ray diffraction and transmission electron microscopy, Materials Structure 14 (2007) 67

M. Schwarz, T. Barsukova, D. Šimek, M. Dopita, Ch. Lathe, D. Rafaja, E. Kroke: In-situ study of HP/HT synthesis of Ti-(Al,Si)-N bulk nanocomposites, HASY-Lab Report (2007) 647

Conference Papers

2013

C. Schimpf, M. Schwarz, E. Kroke, D. Rafaja, Microstructure Defects in Graphitic BN and Their Impact on the Transition to the Dense Phases, 28th European Crystallographic Society Meeting, Warwick, UK 2013

S. Bahmann, Torsten Weißbach, Jens Kortus: Prediction of a hybrid graphene-diamond like phase, DPG Frühjahrstagung 2013, Regensburg

K. Keller, T. Schlothauer, M.R. Schwarz, E. Brendler, E. Kroke, G. Heide, Searching for Hypercoodination. 8th Alpine Conference of Solid State NMR. International Society of Magnetic Resonance. Groupement Ampere and the International Society of Magnetic Resonance. Chamonix/ FRA, 08.09.2013.

F. Lehmann, U. Kirsten, M. Schwarz, M. Reich.: "Entwicklung alternativer Antriebskonzepte für Untertagebohrhämmer in der Tiefbohrtechnik - Eine Machbarkeitsstudie"; Plenary lecture and conference report on the DGMK/ÖGEW-Frühjahrstagung 2013, Fachbereich Aufsuchung und Gewinnung in Celle, DGMK-Tagungsbericht 2013

C. Schimpf, H. Schumann, M. Herrmann, M. Schwarz, E. Kroke, D. Rafaja, Recovery of various microstructure defects in hexagonal boron nitride during field assisted sintering, Thermec 2013, Las Vegas/NV, USA

Lehmann, F.; Kirsten, U.; Schwarz, M.; Reich, M.: Entwicklung alternativer Antriebskonzepte für Untertagebohrhämmer in der Tiefbohrtechnik - eine Machbarkeitsstudie, DGMK/ÖGEW-Frühjahrstagung 2013-1 (Präsentation and Manuskript), Fachbereich Aufsuchung und Gewinnung, Celle, Germany, 18-19 April, 2013. ISBN 978-3-941721-31-9

K. Keller, T. Schlothauer, M. R. Schwarz, G. Heide, E. Kroke, Shock-induced Synthesis and stability of the high-pressure phase of AlN, III International Conference Crystallogenesis and Mineralogy, Novosibirsk, 27 September - 1 October 2013.

Bhat, S.; Lauterbach, S.; Dzivenko, D., Lathe, C.; Bayarjargal L.; Schwarz , M.; Kleebe, H.-.J., Kroke, E.; Winkler, B.; Riedel, R. "High-pressure High-temperature Behaviour of Polymer Derived Amorphous B-C-N", poster presentation at the 2013 Joint APS-SCCM/AIRAPT Conference, 7-12 July, 2013, Seattle, U.S.A.

Namuq, M. A.; Reich, M.; Kirsten, U.; Sohmer, M.; Lehmann, F.; Müller, T.: Concept and Laboratory Experiments for a New Lost Circulation Material Pulser (LCM-Pulser) for Real Time Data Transmission in Boreholes. DGMK/ÖGEW-Frühjahrstagung 2013-1, Fachbereich Aufsuchung und Gewinnung, Celle, Germany, 18-19 April, 2013. ISBN 978-3-941721-31-9

Keller, K., Schlothauer, T., Schwarz, M., Brendler, E., Kroke, E. and Heide, G. "Structural Characterization of shocked AlN-powders". In: 21st Annual Conference of the German Crystallographic Society (DGK). Lecture. Freiberg, 2013.

T. Schlothauer, G. Heide, Chemical composition and thermal stability of shock-wave synthesised spinel-type gamma-silicon nitrides. International Forum of Topical Issues of Rational Use of Natural Resources. Sankt Petersburg, 24.04-26.04.2013.

Keller, K., Schlothauer, T., Schwarz, M., Kroke, E. and Heide, G. "Shock synthesis of high-pressure phases in the system Si-Al-O-N". In: International Symposium on Explosion, Shock wave and High-energy reaction Phenomena 2013. lecture. Nago/ Okinawa, 2013.

Keller, K., Schlothauer, T., Schwarz, M. R., Kroke, E. and Heide, G. "Shockinduced synthesis and characterisation of rocksalt-type AlN". In: Minerals as Advanced Materials III. lecture. Apatity, 2013.

Keller, K., Schlothauer, T., Heide, G. and Kroke, E. "Shock-induced synthesis of high-pressure aluminium nitride with rocksalt structure". In: III International Conference Crystallogenesis and Mineralogy. Lecture. Novosibirsk, 2013.

M. R. Schwarz, T. Barsukova, C. Schimpf, G. Li, E. Kroke, "In-situ pressure calibration for heated multianvil experiments and a complete re-design of multianvil assemblies for synchrotron and non-synchrotron experiments", poster contribution at the 13 Workshop of the IUCr Commission on High Pressure: Advances in Static and Dynamic High-Pressure Crystallography", 8.-11 Sept. 2013, Deutsches Elektronen Synchrotron (DESY), Hamburg.

Keller, K. Dynamic high pressure research at the Freiberg shock wave laboratory. Seminar series on meteorite and impact research. Humboldt University of Berlin. 2013.

Thomas Schlothauer, and Gerhard Heide (2013), Лаборатория Ударных Волн в Горной Академии Фрейберга/ Германия, Cernogolovka. (in Russian, invited lecture)

T. Schlothauer, G. Heide, Properties of shock wave synthesised nitrides. Topical Issues of Rational Use of Natural Resources. Gornyj Institute Saint Petersburg. St. Petersburg, 20 April 2013.

Anan'ev S.Yu., Milyavskiy V.V., Schlothauer T., Mases M., Waldbock J., Dossot M., Devaux X., McRae E., and Soldatov A.V. (2013), Shock compression of carbon nanotubes up to 100 GPa, in Elbrus 2013

M. Schwarz, "The high pressure forms of Si₃N₄, AlN and Si(Al)ON: Synthesis, Properties and Prospects of a New Class of (Super)hard Materials", Invited talk at THERMEC'2013, International Conference on Processing and Manufacturing of Advanced Materials, Las Vegas, U.S.A., 2-6 Dec. 2013

Milyavskiy V.V., Savinykh A.S., Schlothauer T., Akopov F.A., Lukin E.S., Valiano G.E., Borodina T.I., Popova N.A., Borovkova L.B., Ziborov V.S. et al. (2013), Shock induced phase transitions, spall strength and dynamic elastic limit of tetragonal zirconia, in Elbrus 2013

Schlothauer, T., and G. Heide (2013), Качествы нитридов азота синтезированны с ударнами волнами, Saint Petersburg. (in Russ.)

Schlothauer, T., and G. Heide (2013), Infrared Spectroscopy of shock-wave synthesised γ-Si₃(N,O)₄, in III International Conference Crystallogenesis and Mineralogy, Novosibirsk

T. Schlothauer, G. Heide, Infrared Spectroscopy of shock-wave synthesised γ-Si₃(N,O)₄. International Conference Crystallogenesis and Mineralogy. Novosibirsk, 27 Sep - 01 Oct 2013.

T. Schlothauer, K. Grund, G. Heide (2013), Samples from the outer core? The new shock wave laboratory at the TU Bergakademie Freiberg, Sankt Petersburg. (in Russian, invited lecture)

2012

C. Schimpf, D. Rafaja, M. Schwarz, E. Kroke, Microstructure defects in hexagonal BN analysed by XRD line broadening, 100 Years X-ray diffraction, Freiberg 2012

Mandel, K.; Krüger, L.: Spark plasma sintering and compressive strength behaviour under dynamic loading conditions of nanocrystalline WC-Co. Freiberg High Pressure Symposium, Freiberg, 2012

C. Schimpf, D. Rafaja, M. Schwarz, E. Kroke, Impact of Microstructure Defects in Hexagonal BN on the Transition into the High Pressure Phases, BHT 2012

C. Schimpf, D. Rafaja, M. Schwarz, E. Kroke, The impact of microstructure defects on the high pressure/high temperature phase transitions of boron nitride, Joint 2012 COMPRES Annual Meeting & HPMPS-8, Lake Tahoe/CA, USA

C. Schimpf, D. Rafaja, M. Schwarz, E. Kroke, Quantitative analysis of microstructure defects i h-BN and their role in the phase transition to the sp³ hybridised phases of BN, 6th SPINEL Nitrides Meeting, Rüdesheim 2012

Mandel, K.; Krüger, L.: Influence of Sintering Parameters on Densification, Microstructure, Hardness and Fracture Toughness of Nano-crystalline WC-12Co consolidated by Spark Plasma Sintering. MSE Darmstadt 2012

Kirsten, U.; Lehmann,F.; Reich,M.: "Ultrahard materials for drilling applications", plenary lecture at the Freiberg High Pressure Symposium 08-10 October 2012

Lehmann,F.; Kirsten, U.; Reich, M.: "Requirements for materials for percussive drilling in hardrock", plenary lecture at the Freiberg High Pressure Symposium 08-10 October 2012

Namuq, M. A.; Reich, M.; Kirsten, U.; Lehmann, F.: "Plasma explosions: Innovative method for inducing a high pressure pulse for data transmission in boreholes", Postersession Freiberg High Pressure Symposium 08.-10.10.2012

Mandel, K.; Krüger, L.: Spark Plasma Sintering, Strength and Failure Behaviour of Nanocrystalline WC and WC-Co. Freiberg Research Forum Mining and Metallurgy Day, Technical Colloquium 8: Materials under extreme conditions, Freiberg, 2012

M. Schwarz, "Growing single crystals of high-pressure nitrides: Preliminary Results" Presentation at the 6th International Workshop on Spinel Nitrides and Related Materials in Conjunction with the Marie Curie ITN 7th Framework Programme FUNEA Ruedesheim / Rhine, Germany, 9 - 14 September 2012.

Mandel, K.; Krüger, L.; Radajewski, M.: Wirbelstromprüfung an SP-gesinterten Hartstoffen zur Beurteilung der Schädigungsentwicklung bei wiederholten dynamischen Druckbeanspruchungen. In: DACH Annual Conference 2012, Graz, 2012

Lehmann, F.; Kirsten, U.; Mandel, K.; Konieczny, T.: Experimental investigations of the mechanisms of action of percussive rock destruction to describe drilling in hard rock. 4th International Colloquium on Non-Explosive Rock Excavation, Freiberg, 2012

M. Schwarz, C. Schimpf, T. Barsukova, G. Li, E. Kroke, "Offline in-situ pressure calibration for heated multianvil experiments and several other improvements to the multianvil-technique", poster contribution, Joint COMPRES Annual Meeting and High-Pressure Mineral Physics, Lake Tahoe, California, U.S.A., 9 - 13 July, 2012.

Henschel, S.; Krüger, L.; Mandel, K.; Radajewski, M.: Studie zur Impulsformung an Split-Hopkinson-Aufbauten. In: Werkstofftechnisches Kolloquium, Chemnitz, 2012

Lehmann, F.; Kirsten, U.; Mandel, K.; Reich, M.; Krüger, L.: Investigation of the mechanisms of impact rock destruction and comparison with tests on a laboratory test rig. Plenary lecture and conference report on the DGMK/ÖGEW Spring Conference 2012, Exploration and Extraction Division on 19-20 April 2012 in Celle, DGMK Conference Report 2012-2, ISBN 978-3-941721-25-8

Keller, K., Schlothauer, T., Schwarz, M., Heide, G. and Kroke, E. "Shock-induced Synthesis and stability of the high-pressure phase of AlN". In: XI International Symposium on Explosive Production of New Materials. Lecture. Strasbourg, 2012.

Keller, K., Schlothauer, T. and Heide, G. "Shock wave synthesis and stability of the rocksalt-type aluminium nitride". In: Fifteenth International Conference on High Pressure in Semiconductor Physics. Poster. Montpellier, 2012.

Keller, K., Schlothauer, T., Schwarz, M. R., Heide, G. and Kroke, E. "Phase analysis and structure determination of shock-treated AlN powders". In: Colloquium 100 years of X-ray Diffraction. Lecture. Freiberg, 2012.

Keller, K., Schlothauer, T., Schwarz, M. R., Heide, G. and Kroke, E. "Shock Synthesis and thermal stability of rocksalt-AlN". In: The Freiberg High Pressure Symposium. Poster. Freiberg, 2012.

Schlothauer, T., A. Greif, K. Keller, M. R. Schwarz, G. Heide, and E. Kroke (2012), New investigations on shock-wave synthesised high pressure phases in the system Si-Al-O-N, in Program Book AGU Fall Meeting 2012, San Francisco

Schlothauer, T., and G. Heide (2012), Fortschritte im Schockwellenlabor Freiberg, BHT 2012 FK

Silvia Bahmann, Thomas Gruber, Jens Kortus: An evolution strategy for crystal structure prediction, DPG Frühjahrstagung 2012, Berlin, Vortrag

Silvia Bahmann: Entwicklung eines evolutionären Algorithmus zur Kristallstrukturvorhersage, Freiberger Forschungsforum BHT 2012, Vortrag

M.R. Schwarz, J. Ramin, A. Köhler, E. Kroke, "Die Spinell-Nitride gamma-Si3N4 und gamma-Ge3N4: Über erste Versuche der spontanen Nukleation bei Hochdrucksynthesen über 10 GPa", Posterbeitrag auf der Deutschen Kristallzüchtungstagung, 7-9 March 2012, Freiberg

M. Schwarz, C. Schimpf, G. Li, D. Rafaja, E. Kroke, "Advanced Ceramics and New Assemblies with low X-ray Absorption for High Pressure-High Temperature Multianvil Synchrotron Studies", presentation at the 2nd Workshop for Extreme Conditions Research in a Large Volume Press at PETRA III, 10-11 Sept. 2012, Hamburg.

E. Kroke, Precursor Routes to Nanostructured Nitride Materials, University Center Zhengdong, Zhengzhou (China), 18 Sept. 2012 (invited lecture).

E. Kroke, Carbon Nitrides - New Targets and Prospects, 6th International Workshop on Spinel Nitrides and Related Materials, Ruedesheim/Rhine , 9-14 Sept. 2012 (lecture).

E. Kroke, G. Heide, M. Schwarz, T. Schlothauer, K. Keller, Shockwave Syntheses at the Freiberg High Pressure Research Centre (FHP), Shirtsleeve Colloquium, Carl v. Ossietzky University Oldenburg, 08-10 March 2012 (presentation).

E. Kroke, Molekulare Precursoren, Hochdrucksynthesen und (Ultra)hartstoffe: Von graphitischen CNx-Phasen über höher-koordinierte Si-Verbindungen zu Bornitrid-Nanokompositen, University of Stuttgart, 15/02/2012 (lecture).

2011

Krüger, L.; Mandel, K.; Mandel, M.; Henschel, S.: Field assisted sintering of ultrafine grained tungsten carbide cobalt and related mechanical and electrochemical properties. In: EURO PM2011, Barcelona, 2011

Keller, K. and Schlothauer, T. "Shock wave synthesis @ TUBAF. Progress and Possibilities". In: 62nd Mining and Metallurgy Day. Lecture. Freiberg, 2011.

Keller, K., Schlothauer, T., Schwarz, M., Heide, G. and Kroke, E. "Shock Wave Synthesis of Rocksalt-type of Alumininium Nitride". In: XXII Congress and General Assembly of International Union of Crystallography. Poster. Madrid, 2011.

Krüger, L.; Mandel, K.; Seifert, H. J.; Chmelik, D.: Mechanische Eigenschaften FAST-gesinterter WC-6Co-Verbundwerkstoffe. In: 18th Symposium on Composites and Material Composites, Chemnitz DGM, 2011

Mandel, K.; Kirsten, U.; Krüger, L.; Reich, M.: FAST sintered tungsten carbide cobalt materials for applications in rock destruction. In: Friction, Wear and Wear Protection, Karlsruhe DGM, 2011

Kirsten, U.; Reich, M.: "Erfahrungen mit definierten Schneiden bei spanenden Gesteinszerstörungsprozessen aus Kleinkaliberbohrversuchen", Plenarvortrag und Tagungsbericht zur DGMK/ÖGEW-Frühjahrstagung 2011, Fachbereich Aufsuchung und Gewinnung in Celle, DGMK-Tagungsbericht 2011-1, ISBN 978-3-941721-16-6

Keller, K., Schlothauer, T., Schwarz, M., Heide, G. and Kroke, E. "Synthesis of rocksalt-type of AlN with shock waves". In: 49th EHPRG Conference. Lecture. Budapest, 2011.

Keller, K., Schlothauer, T., Schwarz, M., Heide, G. and Kroke, E. "The Shock Wave Synthesis Laboratory at the Freiberg High-Pressure Research Centre (FHP)". In: Joint Meeting DGK, DMG and ÖMG 2011 Crystals, Minerals and Materials. Lecture. Salzburg, 2011.

Keller, K., Schlothauer, T., Schwarz, M., Heide, G. and Kroke, E. "The shockwavelaboratory at the Freiberg High-Pressure Research Centre (FHP)". In: MEMIN Impact Cratering Workshop. Lecture. Freiburg, 2011.

Keller, K., Schlothauer, T., Schwarz, M., Brendler, E., Galonska, K., Heide, G. and Kroke, E. "Properties of shock-synthesized rocksalt Aluminium nitride". In: Materials Science & Technology 2011 Conference & Exhibition. Lecture. Columbus (Ohio), 2011.

Schlothauer, T., M. R. Schwarz, and G. Heide (2011), The Shock-Wave synthesis Laboratory at the TU Bergakademie Freiberg, in 49th EHPRG-Conference Book of Abstracts, vol. 49

Schlothauer, T., Schwarz. M.R., G. Geide, and E. Kroke (2011), MR31A-2193 Shock wave synthesis of -Si3[O,N]4 in the new blasting facility under different conditions, in Programme Book AGU Fall Meeting 2011

C. Schimpf, M. Schwarz, C. Lathe, T. Barsukova, U. Ratayski, V. Klemm, E. Kroke, D. Rafaja, Microstructure Defects in Superhard BN Nanocomposites and Their Effect on the Phase Transformation Kinetics in HP/HT, Diamond 2011, Garmisch-Partenkirchen

E. Kroke, Von molekularen C3N4-Vorstufen über höher-koordinierte Siliciumverbindungen zu ultraharten BN-Nanokompositen, GDCh-Kolloquium, Martin-Luther- Universität Halle-Wittenberg, 04.05.2011 (invited lecture).

2010

Silvia Schumann, Jens Kortus: Prediction by means of an evolutionary algorithm and stability of boron sheet structures, DPG Frühjahrstagung 2010, Regensburg, Vortrag

Silvia Bahmann, Jens Kortus: Prediction of boron sheet structures using an evolutionary algorithm, Psi-k 2010 Conference 2010, Berlin, Poster

Silvia Bahmann, Jens Kortus: Investigation of the multiferroic material BiCrO3, Psi-k 2010 Conference 2010, Berlin, Poster

Lunow, Ch. & Konietzky, H. (2010): Numerical simulation of cutting processes, Proc. II. Protodjakonow-Seminar, Freiberg

E. Kroke, Molekulare Precursoren, Hochdrucksynthesen und (Ultra)hartstoffe: Von s-Heptazinderivaten über höher-koordinierte Si-Verbindungen zu Bornitrid-Nanokomposite, Inorganisches Kolloquium, Ludwig-Maximilians-Universität München, 17.06.2010 (invited lecture).

E. Kroke, M. Schwarz, T. Barsukova, D. Rafaja, C. Schimpf, Synthesis of Superhard Nanocomposites by Microstructural Design, The 12th CIMTEC - World Ceramics Congress and Forum on New Materials, Montecatini Terme, Italy, 06-11 June 2010 (invited talk).

E. Kroke, Von graphitischen Kohlenstoffnitriden über molekulare Tri-s-triazinderivate zu diamantartigen Bornitrid-Nanokompositen, University of Bayreuth (Inorganic Chemistry), Bayreuth, 02/02/2010 (invited lecture).

M. Schwarz, T. Barsukova, C. Schimpf, D Šimek, C. Lathe, D. Rafaja, E. Kroke, New Assemblies for High Pressure-High Temperature Multianvil Synchrotron Studies with low X-ray Absorption, HASYLAB User Meeting, Hamburg, 26.01-29.01.2010.

S. Schmerler, J. Kortus Ab initio molecular dynamics study of interface layer formation at aluminium oxide/silicon nitride interfaces (MM 13.6) Spring Meeting of the Condensed Matter Section, Regensburg, March 21 - 26, 2010 Verhandl. DPG (2010)

S. Schumann, J. Kortus Prediction by means of an evolutionary algorithm and stability of boron sheet structures (MM 43.1) Spring Meeting of the Condensed Matter Section, Regensburg, March 21 - 26, 2010 Verhandl. DPG (2010)

T. Barsukova, C. Schimpf, M. Schwarz, M. Dopita, D. Šimek, C. Lathe, D. Rafaja, E. Kroke, In-situ synchrotron radiation study of BN and Ti-(Al,Si)-N bulk nanocomposites during high-pressure high-temperature synthesis, HASYLAB User Meeting, Hamburg, 26.01-29.01.2010.

M. Schwarz, "Low-Background, high transmission materials and assemblies for multianvil in-situ XRD: Our experiences at MAX200X", presentation at the 1st Workshop for Extreme Conditions Research in a Large Volume Press at PETRA III, 14-15 October 2010, Lüneburg.

2009

Silvia Schumann, Jens Kortus: Application of evolutionary strategies to crystal structure prediction, DPG Frühjahrstagung 2009, Dresden, Vortrag

Lunow, Ch. & Konietzky, H. (2009): Two dimensional simulation of the pressing and the cutting rock destruction, Proc. 2nd Int. Conf. on Computational Methods in Tunneling, Bochum, Aedificatio Publishers, Vol. 1; 223-230

M. Schwarz, "Multianvil calibration and education: A four probe method to measure the entire force-versus-pressure curve in a single run performed as an interdisciplinary lab-course for students", Journal of Physics: Conference Series (JPCS), Proceedings of the Joint AIRAPT-22 & HPCJ-50 conference, 26.-31.07.2009, Tokyo.

S. Schumann, J. Kortus Application of evolutionary strategies to crystal structure prediction (MM 6.1) Spring Meeting of the Condensed Matter Section, Dresden, March 22 - 27, 2009 Verhandl. DPG 44 (2009) 409

M. Schwarz, "Multianvil calibration and education: A four probe method to measure the entire force-versus-pressure curve in a single run performed as an interdisciplinary lab-course for students", Joint AIRAPT-22 & HPCJ-50 conference, Tokyo, Japan, 26-31 July 2009.

E. Kroke, Von graphitischen Kohlenstoffnitriden über höher koordinierte Silicium-verbindungen zu diamantartigen Bornitrid-Nanokompositen, FU Berlin, Anorg. Chem., Berlin, 10.12.2009 (invited lecture).

M. Dopita: Capability of the Combination of Electron Backscatter Diffraction and X-ray Diffraction for the Structural Investigation of Hardmetals, Plansse 12th Seminar, Reutte, 2009.

S. Schmerler, J. Kortus Anharmonic contributions to the phonon density of states of rock-salt AIN (MM 3.3) Spring Meeting of the Condensed Matter Section, Dresden, March 22 - 27, 2009 Verhandl. DPG 44 (2009) 407

M. Dopita: Microstructure and mechanical properties of the WC-Co hard-metals sintered using the SPS, Feldaktivierte Synthese und Kompaktierung moderner Werkstoffe, IKTS, Dresden, Germany, 2009.

T. Barsukova, M. R. Schwarz, E. Kroke, M. Motylenko, M. Dopita, V. Klemm, D. Rafaja, High pressure-high temperature synthesis and characterisation of bulk superhard nanocomposites in the systems B-N and Ti-(Al,Si)-N, 47th European High Pressure Research Group Conference, Paris, France, 06.09-11.09.2009.

2008

M. Dopita, M. Janeček, D. Rafaja, J. Uhlíř, M. Vérone: Grain boundary networks in ultra-fine grained Cu and Cu-Zr polycrystals prepared by equal channel angular pressing, 2nd Workshop on "Nanomaterials: microstructural and mechanical characterisations, simulations", Rouen, France, 2008.

E. Kroke, Molekül- und Materialchemie des Siliciums - aktuelle Forschungsprojekte an der TU Bergakademie Freiberg, Colloquium der Silicone-Abteilung der Momentive Performance Materials AG, Leverkusen, 29.02.2008 (invited lecture).

S. Schumann and T. Hahn Application of evolutionary strategies to the analyses of defects in semiconductors Frühjahrstagung der Deutschen Physikalischen Gesellschaft, Berlin, 25 - 29 February 2008 Verhandl. DPG 43 (2008) 330; ISSN 0420-0195

M. Dopita: EBSD Investigation of the Ultra-Fine Grained Cu and Cu-Zr Alloy Prepared by Equal Channel Angular Pressing, MSE08, Materials Science and Engineering, Nuremberg, Germany, 2008.

M. Schwarz, "Progress in the synthesis of superhard bulk nanocomposites and novel SiAlON-phases and high pressure investigations in the system Si3-xCxN4", lecture at the "4th international Workshop Spinel Nitrides and Related Materials", Rüdesheim am Rhein, 31.8.-05.09.2008.

E. Kroke: Precursor Routes to Nanostructured Nitride Materials, Tianjun University, School of Materials Science & Engineering (China), Tianjin, 18 September 2008 (invited lecture).

T. Barsukova, M. R. Schwarz, E. Kroke, B. Fürderer, H. Reinecke: Mechanical Properties of Superhard Nanocomposites Prepared under High Pressure-High Temperature, EUROMAT-2007, Nuremberg, 10.09.-13.09.2007 (was awarded a poster prize).

M. Dopita: EBSD investigation of the grain boundary distributions in the ultra-fine grained polycrystals prepared by ECAP, ISPMA11, International Symposium in Physics of Materials 11, Prague, Czech Republic, 2008.

2007

Schwarz, E. Kroke, T. Barsukova, D. Rafaja, M. Motylenko, V. Klemm, H. Reinecke, B. Fürderer: On the formation of superhard nanostructures in bulk materials starting from molecular and solid state precursors as compared to thin films, EUROMAT-2007, Nuremberg, 10.09.-13.09.2007.

M. Dopita: Investigation of the sintered hard-metals using the Electron Back Scattered Diffraction (EBSD), The Department of Condensed Matter Physics, Faculty of Mathematics and Physics of Charles University in Prague, Czech Republic, 2007.

T. Barsukova, M. Schwarz, E. Kroke, M. Motylenko, D. Rafaja, B. Fürderer, H. Reinecke: Mechanical Properties of Superhard Nanocomposites prepared under High-Pressure/High-Temperature, 2nd German-Austrian Collaborators Workshop Main Group Element Chemistry, Bad Münster am Stein - Ebernburg (Germany), 26.10-28.10.2007.

TP 1: Prediction of crystal structures

Prediction of possible crystal structures taking into account pressure and temperature effects

Motivation

Mineralogy demonstrates the wide variety of different ways in which atoms can be arranged in a crystal. You only have to think of different silicates, which are all based on SiO2 but have different structures. The possible phases are determined by external conditions such as pressure and temperature. The phases occurring in nature are characterised by their thermodynamic stability, i.e. they are structures with a minimum free energy. The aim is to find these minima in an energy landscape which, however, extends over as many dimensions as variables are necessary to describe the lattice. These are the respective 3 coordinates and 6 lattice parameters per atom to describe the crystal. For just one Si atom and two oxygens, the dimension of the space to be searched is already 15! In addition, the energy landscape is a convoluted mountain range with many mountains and valleys (local minima). For this reason, a systematic search to find possible minima is practically impossible. The aim of this project is to develop methods that allow possible phases for a given number of atoms to be predicted by computer without experimental input data. New approaches are based on genetic algorithms (Glass et al. Computer Physics Communications 175 (2006) 713-720) for the search or neural networks to map the high-dimensional energy landscape.

Own preliminary work

Theoretical Physics at the TU Bergakademie Freiberg focuses on computer-aided materials research. It mainly uses ab-initio methods that allow the parameter-free calculation of the electronic structure and physical properties of solids and molecules. The DFG is currently funding a project on the subject of high pressure. In collaboration with Prof Kroke and Prof Heide, SPP 1236 is investigating experimentally and theoretically which high-pressure phases exist in the Si/Al/O/N element system.

Aims

A genetic algorithm is to be developed for the search for possible phases. The starting point is a freely selected population of lattices for which the free energy is determined using ab-initio methods. The lattices with the highest free energies are discarded. New grids are generated by mutation or inheritance. In the first case, the programme distorts the shape of the lattice and thereby also shifts the atoms or exchanges atoms for each other. In the case of inheritance, one part is taken from each of two lattices and combined to form a new lattice. Alternatively, an attempt is made to map the energy landscape using neuronal lattices. By training a neural grid on known structures, the energy landscape can be mapped and local minima can be quickly identified by coupling with search algorithms.

Working programme

1. Development of a general programme package for solving optimisation tasks based on genetic algorithms. Design of an open interface for the objective functions so that various methods and programmes for calculating the free energy based on density functional theory or classical pair potentials can be used.
2. Design of genetic algorithms for predicting crystal structures and testing on known structures and phase diagrams.
3. Search for new phases in the Si/Al/C/N system in collaboration with Prof. Kroke.
4. Design of neural networks to map the phase space and search algorithms to find local minima based on already known structures.
5. Testing of the neural networks on the Si/Al/C/N system and comparison with the results of the genetic algorithms.

Internal and external collaborations

Within the Krüger-Kolleg, the analysis of the synthesised materials will be supported by the calculation of the physical properties. In addition, similar phases will also be analysed in order to identify any new phases with improved properties. Direct collaboration with the sub-projects of Prof Kroke, Prof Rafaja and Prof Seifert is therefore a matter of course. Outside the Krüger-Kolleg, a collaboration with the group of A. Oganov (ETH Zurich), which has already developed genetic algorithms for such applications, is being sought.

Trivia

Range: Institute for Theoretical Physics
Subproject leader: Prof. Dr J. Kortus
Editor: Silvia Bahmann
Dissertation: "Development of an evolutionary algorithm for crystal structure prediction" - (2013)
associate member: Steve Schmerler

TP 2: New hard materials and high-pressure phases

New hard materials and high-pressure phases in the Si/Al/C/N/(H) element system from molecular precursors - Si/Al/C/N precursor ceramics

Motivation

Materials, based on the binary element systems Si/C, Si/N (silicon carbide and nitride) and Al/N, are used in a wide range of industrial applications. Pure carbon in the form of its high-pressure modification diamond is also used in industry as the hardest material. Intensive research is currently being carried out on other carbon-based (binary) materials and on the ternary materials of the Si/Al/C/N/(H) element system, as it is hoped that the resulting phase combinations and microstructures, depending on the manufacturing process, will result in significantly improved material properties. The use of (multi-stage) high-pressure processes has hardly been investigated to date.

Own preliminary work

In recent years, various research projects have carried out both fundamental and application-oriented investigations into precursor-derived ceramics, hybrid materials, hard materials and high-pressure phases. In most cases, polymer precursors were used and products were synthesised in the element systems C/N, Si/N, B/C/N and Si/C/N. In addition to classical inorganic-chemical synthesis processes using Schlenk and Glovbox techniques, polymer pyrolysis and ultra-high-pressure syntheses using multi-anvil presses, in some cases diamond stamping cells and shock waves, were at the centre of interest. There are currently two DFG-funded projects on the subject of high-pressure research. On the one hand, SPP 1181 is funding investigations into the production of new hard materials through microstructure design and multi-anvil high-pressure experiments. In addition, SPP 1236 is investigating experimentally and theoretically which high-pressure phases exist in the Si/Al/O/N element system.

• M. Jansen (ed.), High Performance Non-Oxide Ceramics, vol. 1 and 2, Springe-Verlag Berlin, 2002
• A. Weimer, Carbide, Nitride and Boride Materials Synthesis and Processing, Chaman and Hall Lodon, 1997.
• A. Zerr, et al, Recent advances in new hard high-pressure nitrides, Adv. Mater., 2006 (18), 2933.
• E. Kroke, Habilitationsschrift (TU Darmstadt), Tenea Verlag, Berlin, 2004.
• E. Kroke, M. Schwarz, Novel group 14 nitrides, Coord. Chem. Rev., 2004 (248), 493.
• E. Kroke, Y.-L. Li, C. Konetschny, E. Lecomte, C. Fasel, R. Riedel, Silazane Derived Ceramics and Related Materials, Mater. Sci. Eng. R, 2000 (26), 97.
• W. Völger, E. Kroke, R. Riedel, C. Gervais, F. Babonneau, T. Saitou, Y. Iwamoto, B/C/N Materials and B₄C Synthesised by a Non-Oxide Sol-Gel Process, Chem. Mater, 2003 (15), 755.
• K.W. Voelger, R. Hauser, E. Kroke, R. Riedel, Y.H. Ikuhara, Y. Iwamoto, Synthesis and characterisation of novel non-oxide sol-gel derived mesoporous amorphous Si-C-N membranes, J. Ceram. Soc. Japan, 2006 (114), 567.

Aims

The main aim of this proposal is the development and application of methods that enable the design and production of extremely hard and wear-resistant materials in the Si/Al/C/N/(H) element system based on molecular starting compounds. Chemical syntheses, followed by high-pressure conversion and densification experiments, will be used initially. Furthermore, these materials and products created as part of other FHP research projects will be tested for their resistance and behaviour under the influence of high pressure in multi-anvil pressing and shock wave experiments, with the overarching and longer-term goal of developing new high-conductivity materials in the Si/Al/C/N/(H) element system.

Work programme

1. Chemical synthesis of molecular and polymeric starting materials: Firstly, starting materials that are as homogeneous as possible and contain the desired elements in a uniform distribution and controllable quantity must be produced. For this purpose, compounds such as aluminium hydrides should be combined with suitable C/N/H compounds. Silicon chemistry also offers a wide range of possibilities for synthesising the structure and composition of pseudo-binary substances in the Si/C/N/(H) system. (Poly)silanes, -silazanes and -carbosilanes and their combinations, for example, are suitable here.
2. Production of powdery starting materials: Cross-linking and unpressurised thermal ageing in different (reactive) gas atmospheres can usually be used to obtain powdered educts for subsequent high-pressure tests. These can be crushed and homogenised in a high-energy ball mill, for example. In order to use high-pressure phases as starting materials for compaction experiments, extremely fine-grained starting powders are to be produced by detonative syntheses as part of FHP project no. 3. In addition, powder syntheses by vapour phase deposition are being considered.
3. Production of pre-compacted moulded bodies: By sintering processes, including in individual project no. 8, spark plasma sintering can be used to produce moulded bodies as starting materials, which are exposed to even higher pressures as described under 6.4. Hot-pressed or cold-pressed moulded bodies can also be used to obtain materials that are as well pre-compacted as possible.
4. Multi-anvil high-pressure experiments: With the aid of the multi-anvil high-pressure press applied for in the 2006 HBFG process, the above-mentioned starting materials, which may already be ultra-hard materials or novel high-pressure phases, are to be compressed at pressures of up to 20 GPa (200000 bar) and temperatures of up to 2500°C.
5. Characterisation: Structure (spectroscopy, XRD, HR-TEM), hardness, modulus of elasticity, are investigated at the institute and together with the project partners (in particular subprojects 3, 4, 6 and 7).
6. Implementation: Drilling tests are carried out with colleagues from subprojects 5 and 6 to develop a marketable product.

Internal and external collaborations

Within the FHP, pre-compacted materials from the spark plasma sintering system and hot-pressed samples will be used as starting materials, as already mentioned in part 6. In addition, if stable moulded bodies can be produced, these will be mechanically characterised using split Hopkinson tests as part of project no. 6. The use of XRD and TEM is indispensable for analysing microstructure and microstructure (SP 7).
Outside the FHP, cooperation with drilling tool manufacturers is being sought via project 5. In addition, contacts with the hard materials industry are to be intensified.

Trivia

Area: Institute of Inorganic Chemistry
Subproject leader: Prof. Dr E. Kroke
Contributors: Dr Marcus Schwarz, Tatiana Barsukova

TP3: Shock wave synthesis

Material synthesis and material modification using shock waves

Motivation

Among the high and ultra-high pressure methods, shock wave-based methods are characterised by their low cost and simple equipment, which allows larger quantities of material to be converted or tested. Due to safety restrictions, this method is only practised at two locations in Germany, the Fraunhofer Institutes in Freiburg and Pfinztal. Internationally, it is mainly the USA, Russia and Japan that use such methods, and access is correspondingly difficult. The "Reiche Zeche" and "Alte Elisabeth" teaching and research mines at the Freiberg University of Mining and Technology offer very favourable space within the university to carry out such experiments on a large scale. Although the alternative method of laser beam-induced shock waves allows more precise control of the process, it has the disadvantage that complex laser technology must be used and the sample quantities are correspondingly small. The applications are predominantly basic research orientated. Shock waves are used in the following areas:

• Synthesis of high-pressure phases
• Comminution and separation processes
• High-energy forming (explosive forming)
• High-energy joining (explosive welding, explosive cladding)
• Testing of materials and components

The method of explosive forming was used industrially at the Freiberg site some time ago. IBExU GmbH (Institute for Safety Engineering, Freiberg) also has experience and technical capabilities in the field of experimental explosion testing.

Own preliminary work

The applicant has set up a shock wave test rig in the teaching and research mine, and an initial series of experiments using the flyer-plate method has been running together with Prof Kroke's working group since October 2006 as part of a joint DFG project on ultra-high pressure synthesis. Prof Krüger's working group also has extensive experience in the field of high-energy forming. The applicant has written his habilitation thesis in the field of analysing non-crystalline solids. He has extensive analytical experience in the characterisation of phases and structures without or with disturbed translational symmetry.

Goals

The applicant would like to develop a new experimental method for the TU Bergakademie that is unique in the German university landscape. The aim is to operate a laboratory for the high-pressure synthesis of new hard materials and high-pressure phases and to develop new technologies for the shock wave-induced chemical surface and microstructure modification of components.

Work programme

1. Construction of flyer-plate test rigs: The existing trainer needs to be expanded and optimised for measuring ceramic-like materials. Appropriate pressure and temperature measurement technology must be set up and suitable calibration materials found. Experimental set-ups for the additional use of shear forces are to be developed.
2. Synthesis: The syntheses are to serve as a preliminary stage for the MAP technique (Prof. Kroke, TP 2) and successful stoichiometries from MAP experiments are to be transferred to the technically simpler shock wave synthesis. The Spark Plasma Sintering plant (Prof. Seifert, TP 8), on the other hand, supplies large-volume pre-compacted samples that are to be subjected to ultra-high pressure transformation using shock waves.
3. Analysis: The synthesised and modified materials must be analysed mineralogically according to their phase composition and structure. X-ray diffraction, spectroscopy and thermal analysis are the main methods used.

Internal and external collaborations

Within the FHP, materials from the spark plasma sintering facility (Prof. Seifert, TP8) and from precusors (Prof. Kroke, TP2) are further processed and represent an important sub-project in the materials production chain. Shock wave synthesis will continue to be used to produce successfully synthesised samples in the MAP (Prof. Kroke) in larger quantities and more cost-effectively.
In the characterisation of the samples, the analysis of the microstructure before and after loading is only useful in collaboration with Prof. Rafaja (SP 7). On the other hand, the working group will perform phase and structural analyses of synthesis and transformation products of the entire colleges. For the calculation of the pressure states during the shock wave test, co-operation with the group of Prof. Konietzky (SP 4) is necessary and planned. In the final phase of the project, material and component tests are to be carried out under practical conditions in the working groups of Prof Reich (SP 5) and Prof Krüger (SP 6). Material-structural input, support and testing is planned for the computer algorithms of Prof. Kortus (SP 1).
Outside of the FHP, cooperation with specialists in shock wave test stands such as the IBExU, FhG für Chemische Technologien in Pfinztal and Ernst-Mach-Institut in Freiburg will be established and expanded.

Trivia

Area: Institute of Mineralogy
Subproject leader: Prof. Dr. G. Heide
Project leader: Thomas Schlothauer
associate member: Kevin Keller
Dissertation: "Shock wave synthesis and characterisation of alumina nitride with common salt structure" - (2013)

TP 4: Simulation of the fracture behaviour of rocks

Micromechanical simulation of the fracture behaviour of rocks under high pressures

Motivation

When penetrating to great depths in the extraction of deposits, deep drilling for oil and natural gas extraction and geothermal energy production, or even for very deep tunnels, knowledge of the fracture behaviour of rocks under high pressures (> 100 MPa) is becoming increasingly important, e.g. with regard to the stability of the rock. For example, with regard to stability (boreholes, excavation cavities, ...), but also the recoverability through drilling, percussion, cutting or blasting processes. Up to now, almost exclusively phenomenological observations with smeared microstructure have been used for simulation. However, the reliable assessment of stability as well as the energy, wear and time optimisation of extraction and drilling processes and tools requires a microstructural investigation of the relationship between rock structure and mechanical load.

Our own preliminary work

The institute has many years of experience in carrying out rock mechanics laboratory tests. Further modern new testing technology (triaxial cell with integrated ultrasonic tool, large shear device, uniaxial press with 5000 kN) has been available since 2007 and the end of 2008. With regard to numerical simulation, experience from DEM simulation is available, e.g:

• Schlegel, R., Konietzky, H., Rautenstrauch, K. "Mathematical description of masonry under static and dynamic loading within the framework of discontinuum mechanics using the discrete element method", Das Mauerwerk, 9(2005), Heft4, pp. 143-150
• Mcdowell, G.R., Harireche, O., Konietzky, H., Brown, S.F., Thom, N.H. "Discrete element modelling of geogrid-reinforced aggregates", Geotechnical Engineering 159, Issue GEI, 2006, p. 35-48
• Konietzky, H., te Kamp, L. "Hydro-mechanical coupling for particle methods" Workshop Grenzschicht Wasser und Boden, 9.3.2005, TU Hamburg-Harburg, Veröffentlichung der TU Hamburg-Harburg Arbeitsbereich Geotechnik und Baubetrieb Nr. 9, S.121-129
• Bock, H., Blümling, P., Konietzky, H. "Study of the micromechanical behaviour of the Opalinus Clay: an example of co-operation across the ground engineering disciplines", Bull. Eng. Geol. Env. (2006) 65: 195-207

Aims

The scientific investigations are based on the discrete element method developed in recent years and accompanying laboratory tests in the triaxial and uniaxial device with on-line ultrasonic monitoring. Based on the developed methodology and software components, geomechanical, deep drilling and mining processes can be optimised by coupling them with optimisation procedures. The aim is to develop a methodology (stochastic structure modelling + numerical simulation based on the discrete element method) including the development of the necessary software components. This set of tools then forms the basis for a wide range of optimisation tasks for specific practical applications, e.g. the optimisation of drilling tools or crushing machines.

Work programme

1. Stochastic structural model: Discrete elements are generated and meshed using point processes or Varonoi structures on the basis of structural analyses relating to the grain structure and, if applicable, the binders.
2. Development and implementation of material laws: The mechanical behaviour of the structural elements (mineral grains and binders) is mapped via contact and volume material laws.
3. Numerical simulation of high-pressure mechanical loads: A DEM simulation is used to realistically map the fracture behaviour of the rock structure under various high-pressure loading regimes in the micro range.
4. Validation through laboratory experiments: For validation purposes, special strength tests are carried out in the rock mechanics laboratory in the high-pressure range.

Internal and external collaborations

External collaboration with the Institute of Stochastics at the TU BAF is being sought. Internally, there is close cooperation with Project 6.

Trivia

Area: Institute of Geotechnical Engineering
Subproject leader: Prof. Dr H. Konietzky
Assistant: Anett Wagner
Dissertation:
Assistant: Christian Lunow
Dissertation: "Simulation of rock mechanical drilling and cutting processes using the discrete element method" - 2014

TP 5: Prototype tool

Development and practical testing of new drilling tools based on ultra-hard materials

Motivation

The exploitation of increasingly scarce natural resources requires penetration to ever greater depths in the earth's crust. Drilling technology is becoming increasingly important in this context. The costs of deep drilling increase disproportionately with depth because the rock strength increases and the drilling speed decreases accordingly. In addition, the greater the depth, the greater the effort required to remove and replace a damaged, defective or worn element (drill bit) of the drill string. Such removal and installation work (round trips) of the drill string, which is often many kilometres long, accounts for a considerable proportion of the total costs of a deep borehole. This applies in particular to geothermal wells that have to be drilled into particularly hot, i.e. deep, horizons. Every round trip that can be saved significantly reduces the overall drilling costs and therefore the commercial risk of the project. Modern drilling rigs must therefore fulfil the highest requirements in terms of durability, reliability and wear resistance. In conventional deep drilling technology, which is geared towards the extraction of oil and gas from porous and permeable layers, great progress has already been made in this sector and very effective drilling methods have been developed. However, in order to economically generate electricity from geothermal energy, much more compact and harder rocks (e.g. granite) must be drilled. The existing drill bits used in oil and gas drilling technology are not optimised for such applications. The development and utilisation of special rock destruction mechanisms for hard rock in combination with the use of ultra-hard and wear-resistant materials offers the potential for significant cost savings and can thus lead to the hoped-for breakthrough of deep geothermal energy on the market. The use of ultra-hard materials for armouring (wear protection) or high-performance bearings, for example, can also help to reduce drilling costs.

Previous work

The project manager has almost 20 years of industrial experience in the field of deep drilling technology. Among other things, he has worked as head of a group for the optimisation of drilling processes on drilling rigs, manager of the field test department for prototype drilling tools and product line manager for automatic directional drilling systems for a leading service company in the oil and gas industry.

Objectives

The aim of this sub-project is to find and prepare marketable applications for the ultra-hard materials developed at the high-pressure centre in deep drilling technology.

Work programme

1. Detailed analysis of the load processes on drilling tools and rock
2. Conclusions for a more effective drilling process in hard rock (e.g. targeted use of impact and percussion processes to generate cuttings of certain size classes, which can be optimally handled as part of the overall drilling process)
3. Development of manufacturing methods for the use of the new ultra-hard materials on the drilling tool
4. Implementation of all findings in the design of a prototype tool
5. .tool
6. Construction and field use of the prototype in collaboration with an industrial partner
7. Detailed comparison of the test results with conventional technology

Internal and external collaborations

Within the Freiberg High Pressure Centre, close collaboration is required with all other sub-projects, especially with those of materials production and characterisation.
Outside the high-pressure centre, the production and field testing of the prototype tools is carried out with one or more relevant service companies in the oil and gas industry.

Trivia

Area: Institute of Drilling Technology and Fluid Mining
Subproject leader: Prof. Dr M. Reich
Editor: Ulf Kirsten
Dissertation: "Contribution to the energetic and tribological investigation of rock drilling processes" - 2014

TP 6: Material behaviour under extreme conditions

Material behaviour of new composite materials under extreme load conditions

Motivation

The extraction of raw materials and the improved exploitation of energy resources require technologies in which optimised tools and new materials are becoming increasingly important. For example, better utilisation of geothermal energy increasingly requires deep drilling. The materials used to date, which are required to have high hardness, strength and sufficient toughness, are reaching their limits. The new materials produced in other sub-projects at different pressures are intended to make a significant contribution to increasing service life. The cutting materials are exposed to impact and shock loads during their operating phase, which contribute significantly to material failure and thus to premature wear. The aim is therefore to produce materials that are suitable for use under impact loads and have an optimised combination of high hardness and strength with sufficient toughness. So far, the impact dynamic strength behaviour of ceramics under compressive load and occasionally the damage behaviour have been investigated internationally and models of the material behaviour have also been derived. Less is known about the failure of hard and high-strength materials and of composite materials with a high hard material content. Furthermore, the influence of multiple impact loads below the breaking strength has hardly been investigated. However, there are indications that these stresses lead to progressive material damage over time and ultimately to failure. However, these are precisely the material problems that are important for hard materials and hard metals for tools.

Own preliminary work

The applicant can refer to extensive work in the field of measuring and characterising material behaviour under slow and impact loading, i.e. in a very wide range of strain rates. For example, the relationships between high-strength metallic materials and composite materials and the behaviour of ceramics and glasses under impact loading and high hydrostatic pressures have been investigated. Several test rigs are currently being set up at the Institute of Materials Technology (IWT), which will soon be used to investigate the new materials. These include a split Hopkinson set-up for high-speed pressure loads and a drop weight tester. The IWT also has many years of expertise in assessing toughness behaviour under impact stress.

• E. O. Hall, Proc. Phys. Soc. London Sect. B 64 (1951) 747; N. J. Petch, J. Iron Steel Inst. 174 (1953) 25.
• S. Veprek, S. Reiprich, Li Shizhib, Appl. Phys. Letters 66 (1995) 2640.
• F. Adibi, I. Petrov, L. Hultman, U. Wahlström, T. Shimizu, D. McIntyre, J.E. Greene, J.-E. Sundgren, J. Appl. Phys. 69 (1991) 6437.
• C.S. Sandu, R. Sanjinés, M. Benkahoul, F. Medjani, F. Lévy, Surf. Coat. Technol. 201 (2006) 4083.
• A.E. Reiter, V.H. Derflinger, B. Hanselmann, T. Bachmann, B. Sartory, Surf. Coat. Technol. 200 (2005) 2114.
• D. Rafaja, M. Šíma, V. Klemm, G. Schreiber, D. Heger, L. Havela, R. Kužel, J. Alloys Comp. 378 (2004) 107-111.
• D. Rafaja, V. Klemm, G. Schreiber, M. Knapp, R. Kužel, J. Appl. Cryst. 37 (2004) 613-620.
• D. Rafaja, A. Poklad, V. Klemm, G. Schreiber, D. Heger, M. Šíma, M. Dopita, Thin Solid Films 514 (2006) 240-249.
• D. Rafaja, A. Poklad, V. Klemm, G. Schreiber, D. Heger, M. Šíma, Mat. Sci. Eng. A (2006)-
• D. Rafaja, M. Dopita, M. Ružicka, V. Klemm, D. Heger, G. Schreiber, M. Šíma, Surf. Coat. Technol. 201 (2006) 2835-2843.

Aims

The aim of the present project is to measure and understand the behaviour of the novel materials to be produced in the overall project under near-stress conditions. This includes the comprehensive investigation of the strength and failure behaviour in a wide range of speeds as well as the interpretation based on material science and the modelling of the material behaviour in cooperation with other sub-projects. These investigations should allow conclusions to be drawn as to which material states or which material structure is particularly suitable for impact loads in cutting tools.

Work programme

1. Optimisation of impact test rigs: First of all, some existing test rigs for measuring ceramic-like materials under compressive load need to be optimised. A split Hopkinson test rig is used for this purpose. Furthermore, a new test rig suitable for high loading speeds must be set up for toughness tests.
2. Strength and failure behaviour: Work will begin on investigating the strength behaviour of commercially available materials that are similar in their behaviour to the new materials. This is followed by investigations into how the newly developed materials react to a load that is in some cases significantly below the breaking strength, but is applied several times. The development of damage must be analysed using destructive and non-destructive material testing. The material changes found and the measured behaviour are incorporated into model laws.
3. Toughness behaviour and speed influence: Investigations into crack propagation behaviour represent a further challenging step. This is uncharted territory, as there is little or no experience worldwide for hard materials, especially for the new materials. However, it is to be expected that a high material quality can be produced using the SPS process. The properties required in the material application are characterised by appropriate test methods and are used for further material optimisation.
4. Correlation of the mechanical material behaviour with microstructures: In this work step, there is close cooperation with other sub-projects. Findings from the microstructure investigations of material states from the SPS process, as well as from materials produced using the multi-anvil technique, are evaluated and compared with results from test bench investigations (component behaviour).
5. Modelling laws: The new findings on the microstructure-property relationships are implemented in model laws and are used to describe the material under impact-like stress and for further material optimisation.

Internal and external collaborations

Within the FHP, materials from the spark plasma sintering system and, where possible, from the multi-anvil press as well as nanocomposites produced with PVD are primarily investigated. To this end, cooperation is taking place with the sub-projects of the material manufacturers (Seifert, Kroke, Rafaja), the characterisation of the microstructure before and after loading (Rafaja) and after component tests (Reich).
Outside the FHP, collaboration is taking place with international experts on the high-speed behaviour of ceramic materials and the production of composite materials.

Trivia

Department: Institute of Materials Engineering
Subproject leader: Prof. Dr. L. Krüger
Bearner: Kristin Mandel
Dissertation: "Investigations on field-activated sintering and the rate-dependent strength and failure behaviour of near-nano WC-Co hard materials under compressive stress" - 2013

TP 7: Structure-property correlations of superhard nanocomposites

Microstructure and mechanical properties of superhard nanocomposites under extreme conditions - Superhard nanocomposites

Motivation

Superhard nanocomposites based on nitrides of transition metals (especially TiN and CrN) are increasingly used in the production of thin films for special applications, e.g. in material processing in the automotive industry, where such nanocomposites are mainly used to coat drills, indexable inserts and milling cutters.For example, in material processing in the automotive industry, where such nanocomposites are mainly used to coat drills, indexable inserts and milling cutters. The aim is to increase the high-temperature stability of the coatings, in particular to increase their corrosion resistance and hardness at temperatures above 1000°C. Good high-temperature stability of the hard coatings allows, among other things, a significant reduction in the use of lubricants and therefore makes a significant contribution to environmental protection. The idea of increasing hardness in nanocomposites is based in principle on the Hall-Petch relationship between the hardness of the materials and the size of the crystallites. In order to achieve a high hardness of the layered material, it is necessary to produce crystallites smaller than approx. 15 nm, whereby the segregation processes in ternary or quaternary materials (Ti-Si-N, Ti-Al-N, Ti-Al-Si-N, Cr-Si-N, Cr-Al-Si-N) are often utilised. The addition of silicon significantly increases the high-temperature stability of the super-hard nanocomposites. During the coating process, residual compressive stresses of over 10 GPa are formed in nanocomposites. From the perspective of basic research, superhard nanocomposites can therefore be very helpful for explaining the behaviour of superhard materials at high pressure, especially for explaining the initial phase of plastic deformation and the collective behaviour of microstructural defects.

Own preliminary work

The description, explanation and utilisation of structure-property correlations in thin-film nanocomposites has been one of the core research topics of the Institute of Materials Science in recent years. The most important results of recent years include the theoretical description of the coherence of crystallites in superhard nanocomposites and the explanation of their consequences for material properties. New materials for the production of superhard thin-film nanocomposites have already been further developed on this basis.

Aims

The aim of the research project is to develop new nanocomposites with adjustable properties (hardness, ductility, wear resistance, oxidation resistance) by using or specifically designing and influencing the physico-chemical processes, such as spinodal segregation, generation of microstructure defects and their self-organisation, inhibition of dislocation movement and grain sliding through partial coherence of the crystallites.

Work programme

1. Production of thin-film nanocomposites using PVD: Thin films based on Ti-Al-N, Ti-Al-Si-N, Cr-Al-N and Cr-Al-Si-N are planned. With regard to the further investigation methods, Si wafers and sintered WC/Co are to be used as substrates.
2. Microstructure characterisation and hardness measurement of produced layers: during microstructure characterisation, phase composition, residual stresses, crystallite size, type and density of microstructure defects and intrinsic stresses at the crystallite boundaries (due to the partial coherence of the crystallites) are to be determined using X-ray diffraction and TEM. Chemical composition of the layers will be analysed by ESMA/WDS and GDOES. The hardness measurement is proposed for the characterisation of mechanical properties.
3. Microstructure investigations after mechanical loading: local microstructure analysis on hardness indentations using transmission electron microscopy, explanation and use of the cooperative processes in the formation and movement of dislocation networks during plastic deformation of the thin-film nanocomposites.
4. In-situ microstructure investigations at high temperatures: investigation of phase stability and crystallite size change at high temperatures; clarification of the influence of oxidation on the mechanical properties of the nanocomposites; proposals for improving hardness and oxidation resistance at high temperatures by targeted modification of the microstructure.

Internal and external collaborations

Within the FHP, the analogy between the bulk materials produced under extreme conditions and the thin-film nanocomposites used under extreme conditions is to be used for the further development of materials for and under extreme conditions. The materials produced as part of the projects (Spark-Plasma-Sintering, H.J. Seifert, TP 8) and (Si/Al/C/N-Precursor Ceramics, E. Kroke, TP 2) are indispensable for this purpose.
Outside the FHPR, the existing collaboration with the manufacturers of hard coatings will be utilised and expanded in order to test the use of the developed materials in practice. Measurement time at the ESRF synchrotron source in Grenoble (for high-pressure experiments) will be requested for in-situ investigation of bulk materials. Synchrotron access (including travel costs) is funded directly by the EU.

Trivia

Department: Institute of Materials Science
Subproject leader: Prof. Dr. D. Rafaja
Researcher: Christian Schimpf
Dissertation: "On the microstructure defects in hexagonal BN and their impact on the high pressure/high temperature phase transition to the dense BN polymorphs" - Freiberger Forschungshefte B354 (2013)

TP 8: Compaction using Spark Plasma Sintering

High-pressure compaction of new hard materials in mechanical engineering using Spark Plasma Sintering

Motivation

Hard materials and carbides as materials for drilling and cutting equipment in mechanical engineering and wear-resistant components generally have to be sintered at very high temperatures (>1800°C) and pressures. This is necessary in order to achieve the densification of the microstructure and the associated optimisation of mechanical properties. However, the conventional process routes of hot pressing or hot isostatic pressing generally result in strong grain growth and the formation of secondary (grain boundary) phases during sintering. Also, complete densification cannot usually be achieved with the required reliability and reproducibility. The measured mechanical properties of the materials therefore fall well short of the theoretically expected values. Spark Plasma Sintering (SPS, also known as Field Assisted Sintering, FAST) represents a new innovative alternative to the conventional hot pressing processes mentioned above. In this process, high process pressures and temperatures are combined with directed direct current pulses. The powder mixtures are very strongly sinter-activated with this method and can be fully compacted at high pressure but comparatively low temperatures. This provides the basis for reliable process control in the production of nanocrystalline and microcrystalline materials. The method has a very high application potential and opens up completely new fields of application for carbides, nitrides and borides and their composite materials in mechanical engineering.

Own preliminary work

The working group has many years of experience in hot pressing, hot isostatic pressing (HIP) and gas pressure sintering of hard materials and hard metals. Using these methods, for example, complex carbides (MAX phases) in the systems Nb-Sn-C, (Ti,Nb)-Al-C and (Ti,Hf)-In-C were successfully produced and characterised with regard to their microstructure, crystal structure, electrical and thermal properties. Using the same approach, the heterogeneous equilibria and phase reactions in silicon nitride-titanium carbonitride ceramics (Si₃N₄ -TiC_xN_1-x) were also fully elucidated.

• W. Chen, U. Anselmi-Tamburini, J.E. Garay, J.R. Groza, Z.A. Munir: Fundamental investigations on the spark plasma sintering/synthesis process, Materials Science and Engineering A394 (2005) 132-138.
• M. W. Barsoum, I. Salama, T. El-Raghy, J. Golczewski, W. D. Porter, H. Wang, H. J. Seifert and F. Aldinger: Thermal and Electrical Properties of Nb2AlC, (Ti,Nb)2AlC, Ti2Al, Metallurgical and Materials Transactions A - Physical Metallurgy and Materials Science 33 (2002) 2775-2779.
• M. W. Barsoum, J. Golczewski, H. J. Seifert and F. Aldinger: Fabrication and Electrical and Thermal Properties of Ti2InC, Hf2InC and (Ti,Hf)2InC, J. Alloys and Compounds 340 (2002) 173-176.

Aims

The starting samples used are sintered high-purity powders and their mixtures. It is also planned to use amorphous or nanocrystalline precursor ceramics of the Al-Si-C-N system as starting materials (SP2). The SPS method allows these samples to be heated up very quickly and compacted with sintering times in the range of minutes. The process conditions can be varied very flexibly. By varying the pressing pressure, sintering atmosphere, direct current pulses and the resulting temperature profile, the grain size distributions in the materials can be specifically controlled. A very important option is to inhibit grain growth by very rapid heating and short holding times at low temperatures (compared to hot pressing), to limit heterogeneous phase reactions and thus to produce dense materials with very fine-grained structures. Microstructures can therefore be created in the samples that are far removed from thermodynamic equilibrium and - in comparison with conventionally sintered samples - exhibit an improved or even completely new property profile. When using suitable starting powders, the method also offers new possibilities for reproducibly producing solid nanostructured moulded bodies with grain sizes smaller than 20 nm in diameter. This has not been achieved with conventional methods to date, or only very unsatisfactorily.

Work programme

1. Production of powder mixtures by attritor mixing or co-precipitation, filtration and drying: In a first step, homogeneous powder mixtures of the base material and the additives are produced. The particle size distribution and the free surface area of the pure starting powders and the powder mixtures after attritor grinding are analysed in detail. If necessary, further process steps are introduced for the defined adjustment of the particle size distribution (e.g. sieving, centrifuging, sedimentation).
2. Spark Plasma Sintering Process: The powder mixtures are sintered. The samples are compacted by varying the sintering programme. The most important process parameters are pressure (up to 250 kN), temperature (up to 2200°C), direct current (up to 10000 A) and pulse rate / pause duration (1-255 ms / 0-255 ms). In addition, the gas atmosphere and the heating programme (heating and cooling rates, holding times) are varied. In this project, Spark Plasma Sintering will also be used to produce moulded bodies that will be used as pre-compacted starting samples for further high-pressure processes (Multi Anvil Cell, TP 2).
3. Sample characterisation: The samples will be examined using X-ray and electron microscopy methods (SEM, TEM in combination with EDX). The composition of the samples and individual phases is determined using electron beam microprobe analyses. The mechanical properties are determined by hardness tests, tensile tests and 3-point and 4-point bending tests.

Internal and external collaborations

Within the FHP, pre-compacted materials from the spark plasma sintering facility and hot-pressed starting materials in TP 2 and 3 will be used for further high-pressure treatments. The use of XRD and TEM is essential for analysing microstructure and microstructure (SP 7). Tests of the materials and components under practical conditions are carried out in SP 5 and 6.

Trivia

Area: Institute of Materials Science
Subproject leader: Prof. Dr H.J. Seifert
Assistant: Milan Dopita
The project ended prematurely and was partially integrated into SP 6.

Basic concept

The main objectives of the transfer project are the further development of different synthesis strategies for the production of tools from the novel bulk hard materials and the testing of the materials in practice.

Depending on the field of application, both small (e.g. powder for grinding additives), medium (e.g. drawing dies for fine wire production) and larger test specimens (e.g. cutting plates or chisel teeth for drilling tools) are to be produced using the new materials.Depending on the field of application, both small (e.g. powder for grinding additives), medium (e.g. drawing dies for fine wire production) and larger test specimens (e.g. cutting plates or chisel teeth for drilling tools) will be produced using the synthesis systems funded by the Dr Erich Krüger Foundation. The aim is to build directly on the technological and scientific progress made and the knowledge gained in the first phase (2007-2012).

The following synthesis routes are being pursued:

• Spark Plasma Sintering (SPS),
• shock wave synthesis, shock wave sintering, shock wave comminution,
• synthesis in the multi-anvil press (toroid module).

Targeted materials and material systems are:

• Nanocrystalline binder-free tungsten carbide (WC) and WC co-hard metals,
• Binder-free, super-hard boron nitride ceramics,
• γ - Si₃N₄ (silicon nitride).

There are a number of challenges that need to be overcome as part of the project:

• Development of synthesis options for the production of customised bulk hard materials in component-like dimensions (e.g. cutting plates, inserts for drilling tools). cutting inserts, inserts for drilling tools, drawing dies for fine wire production),
• further development of manufacturing technologies for the tools,
• development of innovative rock destruction mechanisms and new drilling tools for hard rock processing,
• process reliability and reproducibility.

The synthesised materials are to be tested in the tools listed in the following paragraph in the form of demonstrators to test their performance.

The transfer project for the first phase of the Freiberg High Pressure Research Centre is visible to the outside world through conference contributions and publications in international journals. The results are largely based directly on the work of the 1st phase (2007-2012).

Publications

2015

L. Krüger, K. Mandel, R. Krause, M. Radajewski, Damage evolution in WC-Co after repeated dynamic compressive loading detected by eddy current testing, International Journal of Refractory Metals and Hard Materials 51 (2015) 324
DOI 10.1016/j.ijrmhm.2015.05.005

A. Köhler, T. Schlothauer, C. Schimpf, V. Klemm, M. Schwarz, G. Heide, D. Rafaja, E. Kroke, The role of oxygen in shockwave-synthesised γ-Si₃N₄ material, Journal of the European Ceramic Society 35 (2015) 3283
DOI 10.1016/j.jeurceramsoc.2015.05.009

T. Schlothauer, C. Schimpf, E. Brendler, K. Keller, E. Kroke, G. Heide, Halide-based shock-wave treatment of fluid-rich natural phases, Journal of Physics: Conference Series, accepted
DOI

K. Keller, E. Brendler, S. Schmerler, C. Röder, G. Heide, J. Kortus, E. Kroke, Spectroscopic characterisation of rocksalt-type Aluminium Nitride, Journal of Physical Chemistry C 119 (2015) 12581
DOI 10.1021/acs.jpcc.5b02187

U.W. Bläß, T. Barsukova, M.R. Schwarz, A. Köhler, C. Schimpf, I.A. Petrusha, U. Mühle, D. Rafaja, E. Kroke, Bulk titanium nitride ceramics - Significant enhancement of hardness by silicon nitride addition, nanostructuring and high pressure sintering, Journal of the European Ceramic Society 35 (2015) 2733
DOI 10.1016/j.jeurceramsoc.2015.04.005

C. Schimpf, M. Schwarz, C. Lathe, E. Kroke, D. Rafaja: Corrugations of the basal planes in hexagonal boron nitride and their impact on the phase transition to cubic boron nitride. Powder Diffraction 30 (2015) S90
DOI 10.1017/S0885715615000044

2014

K. Mandel, L. Krüger, C. Schimpf, Study on parameter optimisation for field-assisted sintering of fully-dense, near-nano WC-12Co, International Journal of Refractory Metals and Hard Materials 45 (2014) 153
DOI 10.1016/j.ijrmhm.2014.04.009

K. Mandel, L. Krüger, C. Schimpf, Particle properties of submicron-sized WC-12Co processed by planetary ball milling. International Journal of Refractory Metals and Hard Materials 42 (2014) 200
DOI 10.1016/j.ijrmhm.2013.09.006

M. Schwarz, M. Antlauf, S. Schmerler, K. Keller, T. Schlothauer, J. Kortus, G. Heide,E. Kroke, Formation and properties of rocksalt-type AlN and implications for high pressure phase relations in the system Si-Al-O-N, High Pressure Res. 34 (2014) 22
DOI 10.1080/08957959.2013.857020

K. Mandel, M. Radajewski, L. Krüger, Strain-rate dependence of the compressive strength of WC-Co hard metals, Materials Science and Engineering A 612 (2014) 115
DOI 10.1016/j.msea.2014.06.020

K. Mandel, L. Krüger, R. Krause, M. Radajewski, The influence of stress state on the compressive strength of WC-Co with different Co contents, International Journal of Refractory Metals and Hard Materials 47 (2014) 124
DOI 10.1016/j.ijrmhm.2014.07.011

T.D. Boyko, T. Gross, M. Schwarz, H. Fuess, A. Moewes The local crystal structure and electronic band gap of β-sialons, Journal of Materials Science 49 (2014) 3242
DOI 10.1007/s10853-014-8030-9

Tagungsbeiträge

2015

C. Schimpf, M. Schwarz, C. Lathe, E. Kroke, D. Rafaja: Interplay between microstructure and phase transition kinetics during the conversion from sp²- to sp³-hybridised BN under extreme conditions, Solid-Solid Phase Transformations in Inorganic Materials PTM 2015, Whistler, B.C., Canada

T. Schlothauer, C. Schimpf, E. Brendler, K. Keller, G. Heide, E. Kroke, Halide based shock-wave treatment of fluid-bearing natural phases, Interaction of Intense Energy Fluxes with Matter. Elbrus 2015. Elbrus/ Karbardino-Balkaria/ RF, 01-06.03.2015.

2014

T. Schlothauer, G. Heide, K. Keller, E. Kroke, The Impedance Correction of the Sample Recovery Capsule in the Shock-Wave-Lab at the TU Bergakademie Freiberg. XXIX International Conference on Equations of State for Matter. pl. Elbrus/ Kabardino-Balkaria/ RU, 01.03-06.03.2014.

T. Schlothauer, C. Schimpf, G. Heide, E. Kroke, D. Rafaja, Behaviour of Copper Powder in Shock Synthesis Experiments. Explosive Production of new Materials. EPNM 2014. Krakow/ Poland, 25.05-30.05.2014.

C. Schimpf, M. Schwarz, H. Schumann, C. Lathe, E. Kroke, D. Rafaja, Microstructure defects in graphitic boron nitride: Analysis, modification and impact on the transition to sp³-hybridised BN, European Powder Diffraction Conference EPDIC 14 2014, Aarhus, Denmark

TP 1: High-pressure synthesis of super-hard materials

High-pressure synthesis of super-hard materials and production of wire drawing eyes

At the beginning of the transfer project, small series production of super-hard boron nitride blanks for wire drawing eyes is to be established. The reproducibility of the high-pressure syntheses is to be ensured by, among other things, quality control of the blanks produced (micromechanical characterisation + microstructure analyses).

The blanks will be further processed into sets of wire drawing eyes using the previously established process chain (setting, drilling and polishing by partners based in Central Germany). The diameter gradations and other dimensions of these sets are determined in close consultation with the interested wire drawing companies and partners (mainly companies based in Freiberg). The finished drawing dies are then made available to these partners for more extensive tests with different metals. This results in a broad spectrum of possible fields of application and markets - from mass products (steel wire) to electrical engineering (copper wires) and electronics (e.g. bonding wires for microchips) to special wires for medical technology.

The results of these tests in the wire drawing process are therefore the most important objective of this study, in addition to the increase in synthesis capacities for the boron nitride blanks, which is essential for subsequent commercialisation. Results from the test series will be analysed together with the wire drawing partners using the methods available in the transfer projects and at the TU Bergakademie Freiberg (e.g. scanning electron microscopy).

Based on the test results, an analysis of the market launch of the innovative drawing eyes is to be carried out together with business start-up and business management consultants (e.g. SAXEED). The sales opportunities must be compared with a determination of the investments to be made and the expected operating costs (business plan preparation).

In order to place the product range of the company spin-off on a broader basis in the medium to long term and thus increase its chances of success, further fields of application for the super-hard boron nitride nanocomposites and similar materials are to be explored in parallel with the small series production of the drawing eyes.

Department: Institute of Inorganic Chemistry
Sub-project leader: Prof. Dr E. Kroke
Contributor: Dr Marcus Schwarz

TP 2: Shock wave synthesis, sintering and comminution

Shock wave synthesis, shock wave sintering and shock wave comminution

At present, material syntheses in the range from 20 to 86 GPa are possible in the underground shock wave laboratory at TU Bergakademie Freiberg with complete sample recovery. The sample quantities are up to 2 g high pressure phase. A maximum of 1000 g of explosive was used. The state of the art is the plane-wave method with highly explosive plastic explosives. All processes can be calculated with sufficient accuracy.

In order to significantly increase the amount of synthesised material, it is necessary to use so-called cylinder charges. Their development is one of the main goals of future work. Assuming complete sample recovery, this method can be used for high-pressure synthesis under sometimes very high pressures (> 100 GPa), shock wave comminution of brittle materials and high-pressure sintering (e.g. for ceramic materials). In order to achieve these goals, it is necessary to use both inert gas technology and vacuum technology. Especially the sintering of the sensitive g-Si₃N₄ requires special techniques, e.g. the evacuation of the sample container. The pressures required for the sintering process to be successful are almost three times the pressure of approx. 35 GPa required for the synthesis. The use of up to 20 kg of highly explosive plastic explosives to military standards is possible and occasionally necessary. This results in much more extreme conditions in the sample than during the synthesis.

Shock wave synthesis with a plane-wave apparatus remains the method of choice for tests to synthesise different nitrides. It is theoretically possible to extend this into the pressure range > 300 GPa (3 Mbar) using the reflection method and the colliding shock wave method, for example. Successful development of this method could make it possible to produce further high-pressure phases with special properties and thus open up new fields of application.

Area: Institute of Mineralogy
Subproject leader: Prof. Dr G. Heide
Contributor: Thomas Schlothauer

TP 3: Drilling tool design and testing

Drilling tool design and testing

As part of the sub-project, various test specimens for use in drilling technology are to be produced, tested and evaluated with regard to their advantages over conventional components.

Depending on the available quantity of synthesised materials, a wide variety of test scenarios are conceivable. Examples of this could be:

• Wear protection for drill rods (abrasion): Carbide is applied to the outer diameter of rod connectors as a circumferential strip or in the form of "buttons" and monitored for diameter wear in an endurance test on a test rig to be set up,
• Wear-resistant hammer drill warts (impact and pressure load): individual warts are coated with new types of materials on hammer drills for rock drilling or solid test bodies are prepared for use. After practical use, the wear will be evaluated in comparison with conventional rock drills,
• long-life cutting inserts (shear load): the cutting inserts will be used on the existing drilling test rig for drilling in various rocks and evaluated with regard to wear,
• wear-resistant components for rotary hammers: individual components are exposed to very high wear stresses, particularly in the case of rotary hammers on a mechanical basis. These components are to be replaced/coated with new materials in a demonstrator model and their behaviour investigated in comparison with conventional materials.

Department: Institute of Drilling Technology and Fluid Mining
Subproject leader: Prof. Dr M. Reich
Contributor: Margeritta Mezzetti

TP 4: Spark Plasma Sintering & Material Behaviour

Spark Plasma Sintering and Material and Component Behaviour

In the sub-project, the development of suitable synthesis strategies for the production of bulk hard materials using the SPS process is being pursued further. The focus is now on the use of commercial nanopowders as well as the new powders from shock wave synthesis. For the materials tungsten carbide (WC) and WC-Co alloys, the SPS process parameters already developed are to be used as starting values. For the new material γ-Si₃N₄, which will initially be produced by shock wave synthesis in SP 1, interesting new scientific and technological ground is to be broken in SPS synthesis and characterisation. Another focus of the work will be the development of SPS parameters for the nano-powder from the shock wave comminution.

On the other hand, the material and component behaviour of the synthesised materials will be tested and evaluated. A major challenge for the successful use of components is the production of flawless materials and components for the tools in order to demonstrate their potential in the application. Promising test specimens must therefore be thoroughly tested for defects using non-destructive methods before component testing. For this purpose, a modern eddy current testing device and the high-resolution ultrasonic testing device applied for as well as radiographic testing methods (CT) for some samples or components are to be used.

For material states with outstanding properties, components are to be defined in consultation with the other sub-projects and potential users, with which the performance can be demonstrated in an industrial environment.

Department: Institute of Materials Engineering
Subproject leader: Prof. Dr L. Krüger
Supervisor: Markus Radajewski

TP 5: Structure-property correlations for targeted material design

Structure-property correlations for targeted material design

In the sub-project, both the starting materials and the materials from the different synthesis routes (powders from shock wave synthesis and shock wave comminution, compact materials from SPS and toroid synthesis) are to be analysed in detail with regard to the existing defect structures and (crystalline) phases. The extensive work serves to describe the microstructure of the powders and the synthesised hard materials. The aim is to work out the role of microstructural defects and internal interfaces in the nanostructured materials on the mechanical behaviour and to provide the sub-projects with synthesis focal points with information for even more targeted material production.

Most of the analyses of the phases formed in the powders and the compacted bodies are carried out using X-ray fine structure analysis. A scanning electron microscope is used for the detailed investigation of the material structures synthesised by shock wave sintering, SPS and toroid technology and for the surface analysis of the wire drawing loops (from TP 3) and the drawn wires (possible surface defects). Much more detailed investigations of the inner interfaces will be possible using a high-resolution transmission electron microscope.

This sub-project will thus provide essential information to all other synthesis projects for an even more stress-optimised material design.

Area: Institute of Materials Science
Subproject leader: Prof. Dr. D. Rafaja
Contributors: Christian Schimpf, Florian Hanzig