Borosilicate glass resisting high levels of thermal loading in X=ray tubes

摘要

This borosilicate glass resists high levels of thermal loading. Its properties include: glass transformation temperature above 580 deg C; thermal expansion 5.0-5.5 x 10<-6> K<-1>; hydrolytic resistance is at least in the second class, measured in accordance with DIN ISO 719; Tk100 in accordance with DIN 52 326 is greater than 270 deg C. Its composition by wt % on an oxide basis is : SiO2 65.0-75.0, B2O3 8.0-12.0, Al2O3 1.0-6.0, Li2O 0-4, Na2O 1.0-8.0, K2O 0-5.0, Li2O + Na2O + K2O 5.0 -10, MgO 0.1-3.0, CaO 3.2-6.0, SrO + BaO 0-6.0, ZrO2 1.0-3.0, ZnO 0.5-2.0, MgO + CaO + SrO + BaO + ZrO2 + ZnO 8.0-12.0 with Na2O/K2O /- 1 and if appropriate, the usual refining additives. Also claimed is use of the glass in making X-ray tubes.