Investigation of Al₂O₃/Cr₃C₂ composites prepared by pressureless sintering (part 1)

Alumina composites containing two different sizes and various compositions of Cr₃C₂ were pressurelessly sintered at 1550°C for 2h in a purified Ar atmosphere. The chemical stability of chromium carbide, microstructure, densification and mechanical properties were studied. The phase stability of Cr₃C₂ was found quite sensitive to the temperature and oxygen content in the sintering environment. The addition of Cr₃C₂ played an important role in the grain growth of alumina. Coalescence of Cr₃C₂ was observed along the grain boundaries of alumina in samples containing high Cr₃C₂. By controlling the phase stability, and the amount and particle size of Cr₃C₂, a flexural strength of 500 MPa, 57% enhancement, was obtained.