Particles of BN,and C are added in amounts of 1 to 40% to SiC and Si3N4 ceramics in order to improve their mechanical properties. The ceramics are then processed by sintering, hot-pressing and chemical vapor deposition techniques to produce dense products. Crack deflection at the particles can increase toughness. However the high temperature strength and toughness are determined byphase interactions in the environmental conditions used for testing. Examination of the ceramics by transmission electron microscopy has shown that the carbon and boron nitride particles have a fibrous texture. In the sintered aSiC ceramic the carbon appears as graphite fiber bundles in the triple junctions and as compact graphite particles within some grains. Examples of these inclusions are shown in Fig. 1A and B.
Multi-material adhesive joints with thick bond-lines: Crack onset and crack deflection
