Mechanical properties of pressure-sintered Al2O3-ZrC composites

Alumina-zirconium carbide composites containing up to 0.90 molecular fraction of carbide were prepared by pressure-sintering at 1800 K under pressures of 35 and 50 MPa. Both toughness (evaluated from the indentation cracks length) and flexural strength, first increase with carbide molecular fraction, then decrease. The influence of the sintering pressure is more marked for the toughness than for the flexural strength. The initial increase of the mechanical properties seems to be related to the alumina grain size diminution, and the subsequent decrease to the presence of poorly bonded zirconium carbide agglomerates.