Fatigue of SIC-based ceramics at ambient temperature

The effects of static and cyclic loading on monolithic sintered silicon carbide (SiC) and SiC reinforced with 16 vol.% particulate titanium diboride (SiC/16vol.% TiB₂) have been studied. Tests were carried out at ambient temperature in air on precracked specimens loaded in three- or four-point bending. No crack growth under cyclic loading has been observed in the monolithic silicon carbide. There is an additional cyclic contribution to crack growth after static crack growth has arrested in the composite material. Observations suggest that damage to the titanium diboride particles ahead of the crack tip occurs prior to crack extension through the SiC matrix.