(1. School of Mechanical & Automotive Engineering, Zhejiang University of Science and Technology, Hangzhou,

Hangzhou 310012; 2. Pingyang Qiushi Medical Instrument Co., Ltd., Wenzhou, Zhejiang 325400)

Abstract:The sintering property, bending strength and thermal shock resistance of Al₂O₃ ceramic enwrapped with 10 wt% colloidal silica were investigated. It was found that the compatibility between Al₂O₃ particle and colloidal silica was good, and the coating of colloidal silica on the outer layer of Al₂O₃ powder was steady when the calcining temperature was below 900 ℃. When the temperature was increased to 1000 ℃, a part of colloidal silica peeled off from Al₂O₃ powders and transformed into fine particles, which could promote the sintering property and was useful to enhance the bending strength of Al₂O₃ ceramic, but was negative to the thermal shock resistance. The thermal shock resistance of Al₂O₃ ceramic made from powders calcined at low temperatures was increased because of the low density and pores, and the number of thermal shock resistance cycles (1200 ℃) could reach 11 when the powders were calcined at 700 ℃.

Keywords:colloidal silica, Al₂O₃ ceramic, mullite, thermal shock resistance