Glasses and Glass Ceramics for Sealing to Aluminum Alloys

摘要

Alkali alkaline earth phosphate glasses which hermetically seal to aluminum alloys were developed. They have coefficients of thermal expansion greater than 200 x 10 exp -7 exp 0 C exp -1 and glass transition temperatures below 400 exp 0 C. The relatively low fracture toughness values (K/sub IC/) of the glasses, 0.43 to 0.53 MPa(m/sup 1/2/), (K/sub IC/ of silica = 0.7 MPa m/sup 1/2/) increase by approximately 25% when the glasses are converted into glass ceramics. Depending upon parent glass compositions and heat treatment, crystal phases of sodium metaphosphate, sodium trimetaphosphate, sodium barium phosphate, or sodium calcium phosphate may develop. DC electrical resistivities of the glasses are 10 exp 6 to 10 exp 10 ohm-cm at 230 exp 0 C. (ERA citation 05:027499)