Enhanced Flexural Strength and Thermal Shock Resistance of Alumina Ceramics by Mullite/Alumina Pre-stressed Coating

It is an effective strengthened technique to introduce a coating containing compressive stress on the surface of ceramic.In this work, the mixed slurry of alumina and quartz powder was coated on the pre-sintered alumina body, then the mullite-alumina coating with lower thermal expansion coefficient was synthesized in-situ after pressureless co-sintering.The pre-stressed strengthening of alumina was achieved by the residual compressive stress formed in the coating during the cooling process.The results indicate that, with the increase of the doping content of quartz in the coating, the flexural strength of pre-stressed alumina increases firstly and then decreases.The flexural strength of specimen realizes the highest value when the doping mass fraction of quartz is 15%, and the interface between the