Composite ceramic materials for applications in engineering at high temperature and under severe conditions of thermal shock and a process for their production

摘要

Ceramic composite materials for ingineering applications at high temperature and under severe conditions of thermal shock and a process for their production. The formulated and granulated composite material of the invention is prepared and thus composed of an appropriate mixture formed by an Si₃N₄ matrix (80-95% by weight), BN (3-15%) and sintering additives, TiB₂, Y₂O₃, Al₂O₃ and ZrSiO₄ (10-20%). This formulated mixture, which is shaped by conventional ceramic techniques, gives rise, by sintering, via an optimized thermal cycle in three steps located between 1,300 and 1,400°C between 1,500 and 1,700°C, and between 1,750 and 1,825°C, to ceramic parts which as a whole combine high strength at room temperature with high resistance to thermal shock and high toughness and are suitable for applications in engineering at high temperature and under severe conditions of thermal shock.