Evaluation of Weak Interface Effect on the Residual Stresses in Layered SiC/TiC Composites by the Finite Element Method and x-ray Diffraction

A symmetrically layered SiC/TiC ceramic with a gradual structure was designed by the finite element method (FEM). After sintering, proper thermal residual stress was introduced into the ceramic due to the coefficients of thermal expansion mismatch between the different layers. After different SiC + C interlayers were inserted into the layers to weaken the interface, the effect of the composition of the SiC + C interlayers between the layers on the residual stress was evaluated. It was found that the weak SiC + C interlayer had little relaxation effect on the residual stress distribution. These ceramics were then fabricated by aqueous tape casting, stacking, and hot-press sintering. An x-ray stress analyzer was used to test the surface stress conditions of the sintered materials. The tested surface stress of the layered SiC/TiC ceramic without interlayer was very close to the FEM calculation. However, there were differences between the tested and calculated results of the layered SiC/TiC ceramics with interlayers; the reason for this was analyzed.