Glass metal seal

The Synthesis and Fabrication of Ceramics for Speciai Appiication 131 17.3.2. Preparation of Giasses for Speciai Applications 17.3.2.6. Glass-Metals Seals... 

The use of glass in glass-metal seals is justified by its transparency, its relatively low permeability to gases, its desirable electrical properties, and the relative ease with which it can be fused to metal to make vacuum-tight seals. Glass, unlike many crystalline materials, can be altered to control expansion coefficient, viscosity, electrical resistivity. 

Preparation of Glasses for Special Applications 17.3.2.6. Glass-Metals Seals... 

The stress resulting in a glass-metal seal is related to both the thermal expansion difference and the temperature at which the viscosity of the glass is such that stresses start to form during cooling (setting temperature). Both depend on the cooling rate. Therefore,... 

The formation of strong adhesive bonds of enamel coatings and glass/ metal seals on heating requires the presence of a liquid phase (22-24). The role of the liquid film is to provide the initial adhesion of solid particles as a result of surface tension. The work of adhesion (W ) is given by ... 

G. Wallis, D.I. Pomerantz, Field-assisted glass-metal sealing, J. Appl. Phys. 1969, 40, 3946-3949. 

The elimination of glass-metal seals results in a simpler, less stressed bulb. As a result, the electrodeless lamp potential lifetimes should be superior to the electrode type. In fact, a mechanism for failure has not yet been identified. 

As with glasses, the properties — most notably the thermal expansion coefficients — of glass-ceramics can be controlled by adjusting the composition. In many applications, such as glass-metal seals and the joining of materials, it is very important to match the thermal expansion coefficients to avoid the generation of thermal stresses. 

Connecting tube A Is made from 6mm OD pyrex and after exiting through the bath lid Is joined by means of a glass-metal seal. 

Wallis G, Pomerantz DI (1969) Field assisted glass—metal sealing. J Appl Phys 40(10) 3946-3949... 

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