Effects of interface and residual stress on mechanical properties of ceramic/metal system

Abstract

Effects of interface, especially microstructural change, and residual stress on the mechanical properties of ceramic/metal system were investigated for a selected brazed silicon nitride/stainless steel system. In order to reduce the residual stress by thermal mismatch, thereby to enhance the joint fracture strength, pure Cu was used as an interlayer. The observed microstructural changes within interlayer as well as within brazing alloy were taken into account for finite element analysis(FEA) of residual stress developed in the joint. The 4-point flexural strengths were measured for Si3N4/Cu/stainless steel 316 joints with a thickness change of Cu interlayer. It was found that FEA calculations for residual stress, developed in Si3N4/stainless-steel joints with a Cu interlayer, could explain the location shift in fractured initiation as well as the variation of fracture strength with Cu-interlayer's thickness change.