Mechanical Properties of Spinel-Silicon Carbide Whisker Composites

Spinel composite ceramics reinforced with 0-40vol% β-silicon carbide whiskers were prepared by hot-pressing at 1800°C under 30MPa for 30min. The mechanical properties (bending strength, hardness, modulus of elasticity, fracture toughness) of the hot-pressed bodies were measured. Fully dense composites were obtained in the whisker content up to 30vol%. The composite mixed with 30vol% whiskers showed the highest room temperature bending strength (about 440MPa), which was about two times as large as that of monolithic spinel. These composites had more excellent high temperature strengths than monolithic spinel. The hardness and modulus of elasticity of dense sintered bodies increased with an increase in whisker content. The fracture toughness increased monotonously with increasing whisker content and showed maximum values (3.5-4.0 MPa[sm middot]m1/2) at 40vol%, which were 2.1-2.7 times as large as those of monolithic spinel due to crack deflection and pull-out of whiskers.