Ceramic Seal Design Guidelines

Ceramic-to-metal joints are formed by metalizing the ceramic in the seal area using a multi-layer, thin-film deposition process and then brazing the metal components to the ceramic using precious metal braze alloys. The ceramic used is often alumina (Al2O3) and the metal components must be chosen to have a coefficient of thermal expansion similar to the alumina to prevent undesirable stresses in the finished assembly. If metal components with higher coefficients of expansion such as stainless steel are required, a suitable low-expansion transition piece must be incorporated in the hermetic seal design between the stainless steel and ceramic components.

Low expansion material concept

Low expansion material concept

High expansion housing material concept

High expansion housing material concept

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