Residual thermal stresses prediction for CVD coating/substrate system based on a numerical model

For a chemical vapor deposition (CVD) coating/substrate system, an improved and optimized numerical model is established to predict the residual thermal stresses. This model takes into account both the normal and bending strains and is developed based on the concept of a misfit strain between coating and substrate. Comparisons are presented between predictions from this model and from finite element analysis. The effects of coating thickness, elastic modulus, temperature difference, and multiple deposition on the residual stresses in the coating/substrate system have also been analyzed in detail. Furthermore, some confirmatory CVD SiC experiments with different layers have also been conducted according to the analysis model. The predictions that the multiple deposition system can relieve the residual thermal stresses and reduce the microcracks in the outermost coating effectively, are consistent with the numerical model.