Bond Strength and Elastic Properties of Ceramic Adhesives

Ceramic or inorganic-type adhesives, which are relatively resistant to thermal and mechanical shock and can sustain strengths at temperatures up to 1500°F, have been developed. Several alterations of the basic glassy phase were studied to attain optimum adhesion properties. Included were the incorporation of metal fillers and recrystallizable materials and the application of special formulation techniques to the basic glassy phase. The basic physical properties, thermal expansion, residual stress, and tensile strength, were correlated with bond strength. Average tensile strength values of 5000 psi at room temperature and 3000 psi at 800°F were found. The addition of selected covalent-bonding-type oxides to a barium borosilicate glass resulted in increased strengths at temperatures above 1000°F. The incorporation of metal fillers improved the physical properties of the basic ceramic adhesives. Recrystallized-type adhesives would not develop strong cohesive bonds unless a glassy phase was also present.