Abstract: Al2O3/316L functionally graded material (FGM) is a potential candidate for plasma facing material used in a thermonuclear device. The finite element method is used to analyze thermal stresses during the preparation of Al2O3/316L FGM in order to reduce thermal expansion mismatch among the different coating layers and substrate. The effects of compositional exponent, the coating thickness and the number of graded layers on the residual stresses are analyzed by using finite element software. The results show that all components are subjected to the minimum thermal stresses and the coating endures the action of compressive stress when the compositional gradient exponent p=1.0. Moreover, the effect of thermal stress mitigation is best when n=9. It is also indicated that gradient layer thickness should not be too large. Compared with non-functionally gradient material (NFGM), the optimized FGM exhibits an outstanding effect in the mitigation of thermal stresses. Al2O3 gradient coating is fabricated on the surface of 316L stainless steel with the aid of plasma spraying. The residual stresses at the different positions of Al2O3 coating are measured by X-ray diffraction approach to verify the reliability of the simulation.

Key words: Finite element analysis, Functionally gradient material, Residual thermal stress, Thermonuclear reactor material