Fabrication and thermal shock resistance of HfB2-SiC composite with B4C additives

A HfB ₂ based ceramic matrix composite containing 20 vol.% SiC particles with 2 vol.% B ₄C as sintering additives was fabricated by hot-pressed sintering. The microstructure and properties, especially the thermal shock resistance of the composite were investigated. Results showed that the addition of B ₄C improved the powder sinterability and led to obtaining nearly full dense composite. The flexural strength and fracture toughness of the composite were 771 MPa and 7.06 MPam1=2, respectively. The thermal shock resistance tests indicated that the residual strength decreased significantly when the thermal shock temperature difference was higher than 600 °. The large number of microcracks on the sample surface was the main reason for the catastrophic failure.