ZHANG Qinjian ¹, ZHANG Jianhua ¹, LIU Yu ¹, LI Min ²

（1.Shangdong University of Technology; 2.Tongji University）

Abstract: Bending Strength and Weibull modulus of eight kinds of ceramics samples were studied．It is shown that bending strength rises in the order of linear cutting‚ough grinding‚inish grinding‚olishing‚hermal treatment‚oating once with Al₂O₃ sol‚coating twice with Al₂O₃sol‚coating with composite Al₂O₃－SiO₂ sol．Weibull modulus of composite coating sample is the highest‚nd the thermal treatment sample next．It is known that thermal treatment can blunt the cracks and even heal them．So the radius of the cracks is reduced and bending strength is raised．The coating method can raise bending strength while leading to decrease of Weibull modulus because of causing the cracks of crystalline grain and the crystalline interface．But the composite coating can make the sol grain permeate the substrate deep so that the sruface cracks can be healed obviously．

Key words: Al₂O₃ ceramics‚sol－gel‚ending stress‚eibull modulus