Crystallization Toughening of Ceramic Adhesives for Joining Alumina

Abstract

Alumina ceramics were joined at high temperatures using powdered glasses or gels as adhesives capable of crystallization. The fracture toughness of the joints was improved by subsequent heat treatment, leading to precipitation of crystalline phases. Measured K{sub IC} values increased from values typical of glasses to between 1.1 and 2.3 MPa{center dot}m{sup 1/2}. The increases were limited by only partially controlled interfacial reactions with the alumina and by residual porosity in the joints.