A facility for high pressure high temperature (HPHT) sintering includes a hydraulic press with a toroidal type of the Bridgman chamber. In this apparatus, plastic deformation of a special capsule provides the isostatic state of stress.
The material sintering process is carried out under very high pressure, up to 8 giga pascal, in high temperatures (up to 2400 C), and for short periods of time, typically several dozen seconds. As a result of the simultaneous pressure and temperature effects, the sintering process is much quicker than in conventional (pressure free) methods. A short sintering process duration reduces the growth of grains, which is important in the sintering of nanomaterials. The materials, obtained by the HPHT method, are characterised by high density degree (up to approximately 99.9%), isotropy of properties and, sometimes, by a totally different phase composition compared to the same material, sintered without pressure, for different thermodynamic process conditions.
The apparatus enables sintering of extra hard materials on the basis of polycrystalline diamond and polycrystalline regular boron nitride, which is in particular used for cutting tools . Moreover, it enables sintering of nanopowders, ceramic composites and high-melting point materials. It also ensures the synthesis of new materials and metastable phases, which cannot be obtained by other methods.
