New nanostructured nitride bulk hard materials

The BMBF-funded junior research group N³V is working on the development of new, binder-free hard materials for use in metal and ceramic processing as well as in the extraction of raw materials.

Further information on the research objectives and results can be found on the N³V project website.

The project is funded by the Federal Ministry of Education and Research (BMBF) within the framework programme "From Material to Innovation" (funding code: 03XP0262).

Contact person

Dr. Kevin Keller

Scientific assistant

Brennhausgasse 14 / Lessingstr. 45 (high-pressure laboratory)

Phone +49 3731 39-2211
Kevin [dot] Keller [at] mineral [dot] tu-freiberg [dot] de (Kevin[dot]Keller[at]mineral[dot]tu-freiberg[dot]de)

Development of filling materials and surface cladding materials for explosion protection mats and walls based on innovative composite materials

Both during the disposal of explosive ordnance and during demolition blasting, the immediate side effects include the dangers of a pressure wave caused by detonation, blast vibrations, flying fragments, vibrations caused by collapse, fire and explosion. For this reason, vulnerable goods in the immediate vicinity of the blast object must be protected from destruction. Special protective measures must be taken to secure the scene of both incidents. To protect the population and to secure buildings and socio-economic and socio-cultural infrastructures, the person authorised to detonate defines a safety radius in which buildings may have to be evacuated and roads cordoned off.

In order to prevent the blast wave and splinters from spreading in the event of a detonation, the blast sites are covered with various aids, such as blast mats, straw, paper bales, sand (bags), insulating mats, concrete blocks or water-filled containers. Paper and straw are usually easily accessible and have a very good insulating effect, but they are highly flammable. Stones, concrete blocks and water containers can exert pressure on the explosive devices and trigger a premature explosion.

The aim of the AiF joint research project is therefore to develop mobile, lightweight and explosion pressure shock-resistant materials and modular protective elements; designed as explosion protection mats and bags to protect against injuries and damage.

Another goal is the development of damping material in the form of foam glass (open- and closed-cell), which can also be intruded with water to increase its effectiveness if required. In particular, SMEs from the field of material production (yarn manufacturers, weavers, coaters, fabricators) and foam glass manufacturers, but also public authorities (explosive ordnance disposal), can open up new fields of application and increase their competitiveness.

Project partners:

• Institute of Glass and Glass Technology
• Sächsisches Textilforschungsinstitut e.V.
  

Contact person

Prof. Dr. Gerhard Heide

University Professor

Brennhausgasse 14

Phone +49 3731 39-2665
Gerhard [dot] Heide [at] mineral [dot] tu-freiberg [dot] de (Gerhard[dot]Heide[at]mineral[dot]tu-freiberg[dot]de)

Determination of dynamic material characteristics

Together with Nordmetall GmbH, material characteristics and state changes of various metallic and ceramic materials are determined under highly dynamic loads. The shock wave tests use VISAR technology to measure shock and material velocities up to several kilometres per second, from which state parameters such as pressure, density and specific volume can be calculated under these conditions.

Contact person

Prof. Dr Gerhard Heide

University Professor

Brennhausgasse 14

Phone +49 3731 39-2665
Gerhard [dot] Heide [at] mineral [dot] tu-freiberg [dot] de (Gerhard[dot]Heide[at]mineral[dot]tu-freiberg[dot]de)

• "NanoPD: Development of innovative ultra-precision tools with ultra-hard nano-polycrystalline diamonds (NanoPD) from HP/HT direct synthesis as cutting material", BMWi project ZIM ZF4097503GM8 (duration 2019-2021)
• "Investigation of phase equilibria in the Fe-N system in the GPa pressure range" (duration 2018-2021)
• "Flintstone2020: Next generation of superhard non-CRM materials and solutions in tooling", EU project Horizon2020 689279 (duration 2016-2020)
• "High-pressure torsional stress-induced phase transformation in titanium and titanium alloys", DFG project (duration 2015-2020)
• "TRIP matrix composite - Design of tough, transformation-reinforced Fe-ZrO₂-based composites and structures, subproject: Interfaces and microstructure-related deformation mechanisms in TRIP matrix composites", DFG project SFB 799 (duration 2008-2020)
• "BNNCut: Development of innovative cutting tools made of nanocrystalline, binder-free boron nitride ("boron nitride nanocomposite" - BNNC) to improve surface quality and extend process limits", BMWi project ZIM (duration 2016-2018)
• "Correlated magnetism: From frustration to topology, subproject: material synthesis under high pressures", DFG project SFB 1143 (duration 2015-2018)
• "BHMZ: Freiberg Biohydrometallurgical Centre for Strategic Elements, subproject: kinetics of leaching processes on natural and synthetic lead-zinc-ores and related ore-minerals", 2. Krüger-Forschungskolleg (duration 2013-2018)
• "Polymer-derived ceramic resistive heater", CSC project 2010704015 (duration 2011-2018)
• "Nanoscale inorganic materials by molecular design: New materials for future-oriented technologies, sub-project: (Super)hard nanocomposites", DFG project SPP 1181 (duration 2005-2018)
• "CarboPaT: Structures, properties and reactions of carbonates at high temperatures and pressures", DFG project FOR2125 (duration 2015-2017)
• "Production of a compact sintered body made of aluminium nitride with common salt structure (rs-AlN) for the determination of material-specific properties", BMWi project SIGNO (duration 2014-2015)
• "FHP: Freiberg High Pressure Research Centre", 1. Krüger-Forschungskolleg (duration 2007-2015)
• "Unconventional synthesis of ternary and quaternary nanoscale nitrides using shock waves (synthesis), Leuchtstoffwerk Breitungen GmbH", Thüringer Aufbaubank 2011FE9045 (duration 2013-2014)
• "ADDE: Functional Structural Design of New High Performance Materials by Atomic Design and Defect Engineering, Subproject: New Volume Hard Materials", State Excellence Initiative (Duration 2009-2014)
• "Structures and Properties of Crystals at Extremely High Pressures and Temperatures, Subproject: The System Si-Al-O-N at Extreme Pressures: A Synthetic and Computational Route to Novel Materials?", DFG project SPP 1236 (duration 2006-2011)

The tooling that is built on critical and scarce raw materials (CRMs) occupies over 80 per cent of the entire global tooling market just in metal cutting area. The CRM-containing tooling is divided into three major material groups: Cemented carbide, polycrystalline diamond and cBN, and tool steels, in the descending order of importance and CRM impact. Consequently, a huge consumption of tooling leads to significant use of these critical and scarce raw materials, tungsten and cobalt globally.

Flintstone2020 aims to provide a perspective for the replacement of two important CRMs - tungsten (W) and cobalt (Co) - which are the main constituents for two important classes of hard materials (cemented carbides/WC-Co, and PCD/diamond-Co), by developing innovative alternative solutions for tooling operating under extreme conditions in the following application areas:

1. Machining ferritic and pearlitic materials (steels and irons);
2. Machining austenitic materials (stainless steels and superalloys);
3. Machining titanium alloys and other special materials (composite materials);
4. Machining martensitic materials (hardened steels);
5. Cutting and processing rock and concrete.

In the project part of the TUBAF binder systems for the hard materials c-BN and diamond (nanocrystalline and/or (partly) amorphous) based on different (ceramic) sytstems and by different routes (polymer-ceramic route, classical powder route, chemical synthesis) were developed. Samples were produced by HPHT sintering and tested according to their phase composition, microstructure, mechanical properties and interface and bonding between the hard phase and the binder.

Further Information: Flintstone2020 webpage
Contact Person: Dr Marcus Schwarz

The topic of the project is the synthesis and crystal growth of selected frustrated magnetic materials under high pressure and high temperature conditions. We will focus on those structural classes that are expected to exhibit geometric frustration, in particular pyrochlore, spinel and perovskite variants, and will both synthesise known materials and search for new representatives of these classes. Rare earths, selected 3d elements and heavy 5d transition metals with strong spin-orbit coupling such as Ir and Os will be used as magnetic ions.

Further information: SFB 1143 website
Contact: Dr Marcus Schwarz

Freiberger Biohydrometallurgical Centre for Strategic Elements (BHMZ)

The aim of the Freiberg Biohydrometallurgical Centre is to develop a process chain for metal extraction from ores, tailings and recycling material. With the help of this centre, not only should the permanent and safe availability of metals be guaranteed, but the pollution of water, soil or air during mining should also be prevented and energy consumption minimised. Thirteen chairs and a total of 15 doctoral students as well as numerous employees and student assistants are working towards this goal. The focus of the interdisciplinary research is on the two elements indium and germanium.

In the mineralogy sub-project, the leaching behaviour of sulphide ores is being investigated in chemical and biological leaching approaches. The aim is to gain a better understanding of the dissolution mechanisms that also underlie natural weathering. The leaching experiments are carried out with natural lead-zinc ores from the Erzgebirge (mainly sphalerite) and also with synthetic sphalerite. The production of, for example, indium-doped, chemically and structurally well-characterised material is carried out using gas phase transport and high-pressure, high-temperature treatment (toroid press).

Further information: Sub-project page BHMZ
Contact person: Prof. Dr. Gerhard Heide

Polymer precursor derived ceramics resistive heater for multi-anvil and toroidal HP/HT experiments

Recently, numerous efforts have been made to significantly extend the pressure and temperature range as well as sample volume in high pressure high temperature (HP/HT) experiments, especially with the aim of opening up the research areas of geoscience and materials science. HP/HT apparatus thus becomes an important experimental tool of all above researches. There are various HP/HT apparatus which could achieve a range of pressures and temperatures with different sample sizes. Normally, relative large volume sample could be obtained by multi-anvil type and toroidal type HP/HT apparatus.

During the HP/HT experiments, the setup of the assembly will affect the results strongly. The assembly usually contains furnace (resistive heater and insulator), pressure medium and thermocouple etc. Among all the parts, furnace may be the most important part. Temperature increases when the electric current flows through the resistive heater. Hence the properties of the resistive heater are the concern of researchers.

The widely used materials for the resistive heater are graphite, high melting point metals, LaCrO₃ and some composites. However, graphite is limited to 10 GPa due to the transformation to diamond; doped diamond need more fabrication work; metals are usually expensive; LaCrO₃ has a high activation energy, which leads to difficult to "start" at room temperature; composites showed some good results, while the fabrication usually requires high temperature sintering in advance. Besides the materials selection, machinability is another consideration ingredient. The widely employed shape of the furnace in large volume HP/HT apparatus is tube like. Thus the tubular form of the resistive heater should be possible/easily to be machined.

To overcome the drawback of above, a new polymer-precursor-derived composite (PPDC) for resistive heater in HP/HT apparatus will be investigated, polymer-derived ceramics (PDCs) processing was used for the possibility of low fabrication temperature and easily manufacture. The processes and properties related to the preparation and HP/HT runs will be studied.

Contact: Dr Marcus Schwarz

The Institutes of Inorganic Chemistry, Prof. Kroke, and Mineralogy, Prof. Heide, hosted the DFG research group "CarboPaT" on 21 and 22 April. CarboPat stands for "Structure, properties and reaction of carbonates under high pressures and temperatures", conditions that prevail in the Earth's mantle.

This work is of great importance for understanding the global carbon cycle: what contribution does the subduction of oceanic carbonates make, for example? For example, what contribution does the subduction of oceanic plates make and what is the behaviour of CO2, carbonates and organic carbon under pressures well above 1GPa and temperatures above 1000 Kelvin.

The scientists involved in the research group work at the universities of Frankfurt, Potsdam, Dortmund and Freiberg and at the large research institutions DESY Hamburg, GFZ Potsdam and the BGI Bayreuth. The conference was held in the seminar room of the "Reiche Zeche" research and training mine as well as the seminar room in the Krüger House. The head of the shock wave laboratory at the Freiberg High Pressure Research Centre (FHP) of the Dr.Erich Krüger Foundation, Thomas Schlothauer, presented the globally unique possibilities of dynamic high-pressure synthesis in Freiberg.

In addition to the presentations and discussions of the 7 working groups, the director of the major US research project Deep Carbon Observatory (DCO) Craig Manning was the keynote speaker at this 3rd CarboPaT meeting. CarboPaT meeting.

Further information: FOR 2125 website
Contact persons: Prof. Dr Edwin Kroke, Prof. Dr Gerhard Heide