| 摘要 |
Composite articles and cutting tools are prepared by densification to form a body consisting essentially of particles of hard refractory boride uniformly distributed in a silicon nitride matrix consisting essentially of a first phase and a second phase. The first phase consists essentially of crystalline silicon nitride and the second phase is an intergranular refractory phase comprising silicon nitride and a suitable densification aid selected from the group consisting of yttrium oxide, cerium oxide, zirconium oxide, hafnium oxide and the lanthanide rare earth oxides and mixture thereof. The resulting composite article or cutting tool has a fracture toughness equal to or greater than about 4 MN/m3/2. |
