LOW EXPANSION COPPER ALUMINOSILICATE GLASSES

The thermal expansion coefficients of Cu2OAl2O3SiO2 glasses have been measured. These glasses have very low expansion coefficients similar to that for SiO2 glass, but their liquids temperatures are much lower. It was possible to reduce the liquids temperature by the addition of 2 mol% of Na2O while maintaining low expansivity. In order to explain the low expansivity, the effects of cation size, valence, the Cu2+/Cu+ ratio, bond strength and phase separation were examined. Phase separation was observed in these glasses which probably consisted of a copper-rich dispersed phase and a network former-rich matrix phase. It was concluded that the overall expansion coefficients of the glasses were governed by the low expansion matrix phase. © 1979.