Evaluations and Modelling of Residual Stress of a joining- Sialon to Austenitic Stainless Steel

It is not easy to join ceramic to metal due to the differences in the coefficient of thermal
expansion of the two materials. The residual stress present has caused failure to the
joining. Materials with a relatively low elastic modulus can accommodate strain and will
tend to deform under the influence of this stress, while brittle materials such as glasses
and ceramics, will have a tendency to fracture. The evaluations and modelling of
residual stress of a joining-sialon to austenitic stainless steel was simulated using Finite
Element Analysis (ANSYS 1 0) software and simple analytical model was used to
evaluate the residual stress. The joining process was assumed as direct diffusion
bonding. The stress contour plot was discuss based on failure criteria. It is found that at
the area nearby the joining interface, stainless steel experiences tensil~ stress while
ceramic experiences compressive stress. The stress intensity is the highest at a few
points at the ceramic interface compared to the steel interface. Crack occurred at these
points due to the mismatch of thermal expansion and the inability of ceramic to
withstand the high concentration of tensile stress.