The toroidal high-pressure, high-temperature apparatus is comparatively simple in its design and mode of operation and, like the Multi-Anvil Press (MAP), is one of the large-volume presses.
Toroidal high-pressure cell with lower plunger in 1000 tonne high-pressure press before the testThe uniaxial pressure of the high-pressure press is transferred to the sample located in a cylinder, which is surrounded by a toroidal gasket material. Due to the partial flow (outward extrusion), the pressure is transferred to the sample as evenly as possible (quasi-isostatically) and pressure relief to the side is prevented by the rigidity of the material. The maximum usable pressing pressure (and therefore the pressure in the sample) is primarily limited by the stability/flowability of the gasket material. If it flows too strongly, the pressure escapes sideways; if it is too stiff, a blowout occurs.
The following parameters characterise the toroidal high-pressure cells used at the FHP (standard: Tor-13.5, Tor-20; additional: Tor-8.5, Tor-30).
- Pressures up to 12 GPa (depending on press pressure and gasket material, determined experimentally via calibration tests)
- Working volume approx. 1 cm3
- Temperatures up to >2000 °C (only for a short time due to the thermal load on the hard metal press plungers)
- Various heater materials and geometries possible, standard: graphite tube furnace