Glasses Resistant to Sodium Vapor at Temperatures to 700°C

Glasses resistant to attack by sodium vapor at temperatures up to 700°C were developed from the CaO-Al₂O₃-MgO-BaO-B₂O₃ system. The resistance of these glasses decreases sharply above the transformation temperature. The glasses have a high water content, have good wetting properties, and adhere well to materials such as aluminum oxide and niobium; thus they can be used as solder glasses and metalizing components. The surface layer formed on the glass during attack by sodium vapor has a specific electrical resistance which is lower by 2 to 3 orders of magnitude than that of glass not exposed to sodium vapor.