Refractory Glass and Glass Ceramic Tube Seals

Complex vacuum-tube envelopes are required to house and support integrated thermionic circuits (ITC) during long-term operation at elevated temperatures. Li2O-ZnO-SiO2 glass ceramic and CaO-A12O3 glass seals were investigated because they are refractory, moldable, have relatively high thermal expansion coefficients, and bond directly to a variety of metals.