초록 ▼

The invention relates to dense shaped articles of polycrystalline aa2 up to 1450°C. and low subcritical crack propagation under mechanical stress. The fracture mechanism is trans granular up to at least 1450°C. The shaped articles are manufactured by simultaneously shaping and hot pressing pulverule

The invention relates to dense shaped articles of polycrystalline aa2 up to 1450°C. and low subcritical crack propagation under mechanical stress. The fracture mechanism is trans granular up to at least 1450°C. The shaped articles are manufactured by simultaneously shaping and hot pressing pulverulent a

대표청구항 ▼

A process for the manufacture of shaped articles of polycrystalline silicon carbide having a density of at least 99% of the theoretical density of SiC, consisting essentially of: at least about 98.8% by weight of a0.1 to 0.4% by weight of aluminum; up to about 0.4% by weight of nitrogen and/or phosp

A process for the manufacture of shaped articles of polycrystalline silicon carbide having a density of at least 99% of the theoretical density of SiC, consisting essentially of: at least about 98.8% by weight of a0.1 to 0.4% by weight of aluminum; up to about 0.4% by weight of nitrogen and/or phosphorus; up to about 0.2% by weight of oxygen; and up to about 0.2% by weight of carbon, the a12 ma600 N/mm2, up to at least 1450°C., measured according to the four-point method at a stress rate of at least 3 N.mm-2.sec-1, and a predominately transgranular fracture mechanism, said process comprising: (a) forming a homogeneous mixture of pulverulent silicon carbide substantially in the form of the a3 m0.1 to 0.4% by weight of the mixture calculated as free aluminum based on the total weight of solid constituents of an aluminum-containing additive as a sintering aid, and (b) hot-pressing the mixture in a die at a temperature of from 1850°C. to 2300°C. and a die pressure of at least 100 bar in an atmosphere inert to silicon carbide or in a vacuum for a sufficient length of time to form the desired product.