Effects of the metal workpiece properties on the residual stresses in silicon nitride-metal brazed joints

Abstract

Modelling, but more importantly, measurements of residual stresses are needed to guide the design and development of high integrity ceramic/metal joints. This study evaluates the influence of the metal workpiece on the residual stress state present in the ceramic part of the joint. Si3N4 was directly bonded via the active metal brazing route to several metals Cu, Mo, W, Ta, Nb, Zr, Ti, and AISI 316, selected to cover an extended range of thermomechanical properties. The residual strains in the joints were measured using an x-ray diffraction technique. The results indicate that the maximum residual stresses scale with the thermal mismatch for metals with low coefficients of thermal expansion. The experimental results are compared with analytical calculations of the residual stresses.