Low Expansion 'Solder' Glasses in the System ZnO-B2O3-V2O5

JSGT 1956 V40 T252-T259

The region of glass formation was determined in the ternary system ZnO–B₂O₃–V₂O₅ by using a micro-scale glass-melting technique. Thermal expansion measurements were made on a number of glasses in the system, when it was found that the effect of adding up to 20 wt% of V₂O₅ to zinc borate glasses results in a considerable lowering of the deformation temperature, Mg, without appreciably affecting the expansion coefficient, which lies in the range 45–50×10⁻⁷ • One glass composition was selected and it was shown that, with small modifications in its composition to improve its durability, this glass could be used as a solder glass for Fernico sealing glasses. The temperature at which the solder glass formed vacuum-tight joints was 625°C.

E. P. Denton & H. Rawson