The Reduction of Residual Stress Generated in Metal-Ceramic Joining

Abstract

Finite element analysis was used to investigate the effect of altering the interface geometry on a axi-symmetrical metal-ceramic joint. The authors found that increasing the interface angle not only eliminated the singularity that existed at the intersection of the free edge and the interface boundary, but also saw a drastic reduction in the peak residual stresses contained in the joint. An experimental program was undertaken to validate the theoretical result. Electrical discharge machining was utilized to fabricate ‘novel’ convex ceramic interfaces with a variety of apex heights on a conductive, commercially available sialon ceramic. They were subsequently joined, using a Ag-Cu-Ti braze, to mating stainless steel members. Subsequent tensile tests showed a dramatic increase in tensile strength compared to planar interface joints, thus validating the theoretical model and expanding the potential for metal-ceramic joints to be used in engineering applications.