Strengthening Alumina by Quenching in Various Media

In well-made polycrystalline alumina ceramics subjected to external forces, fracture originates at surface flaws. In this investigation, compressive surface layers were formed by quenching both glazed and unglazed alumina rods in various quenching media. Improvements in flexural strength, tensile strength, thermal shock resistance, and impact resistance were observed. The strength increases with increasing compressive surface force as indicated by rod tests. Therefore, in quenched alumina compressive surface layers prevent surface flaws from acting to cause failure.