SEALING GLASS HAVING A HIGH INFRARED-RADIATION ABSORPTION COEFFICIENT

摘要

This invention is concerned with sealing glasses exhibiting a coefficient of absorption of infra-red radiation within the range of 0.7-4 microns of at least 98%, an average coefficient of thermal expansion over the range of 20 DEG -300 DEG C. between 88-92.5x10-7/ DEG C., and a volatilization of less than about 200 ppm at the sealing temperature, said glass being essentially free from K2O and B2O3 and consisting essentially, in weight percent on the oxide basis as calculated from the batch, of - SiO2 67-73 - Al2O3 3.5-6.0 - Li2O 1.0-3.0 - Na2O 10-16 - BaO 3.0-5.5 - Fe2O3 2.0-4.0 - F 0.1-0.4 - TiO2 0-3 - ZrO2 0-3 - ZnO 0-2 -TiO2 + ZrO2 + ZnO 0-4 - the sum of those components constituting at least 98% by weight of the glasses. The glasses are especially suitable as envelopes for reed switches.