Glass-metal seals: The role and conditions of metal annealing before sealing to glass

It is generally recommended that the chromium-containing alloy blanks used to produce vacuum-tight glass-metal seals be previously annealed in humid hydrogen. Using the H47XT alloy sealed to C95-2 chemical glass as an example, it is shown that annealing, of the alloy in humid hydrogen at a temperature of 1050-1100degreesC leads to formation of a durable oxide film on the surface of the blank. The film is highly wettable with melted glass. Our experiments showed that preliminary annealing can also be performed in an atmosphere of humid argon or helium at a temperature of 1050-1100degreesC for I h. Highly explosive hydrogen can thus be excluded from the production process. The seals obtained by this method are on a par with those produced by the conventional procedure.