Residual Stress Field of Ellipsoidal Ceramic Particles Ni-Base Alloy Composite Coating

Abstract

Ni base alloy ceramic composite coating fabricated through vacuum fusion sintering process can acquire high strength and good thermal fatigue resistance. Composite coating was mainly composed of Ni base alloy and ellipsoidal ceramic particles with random orientation. The three-phases model is used to study the thermal expansion strains in composite coating. First, Eshebly-Mori-Tanaka method was used to determine effective eigen strain of two-phases model formed by the ellipsoidal matrix shell being around a ellipsoidal ceramic particle, then disturbance strain in two-phases model aroused thermal inconsistency is obtained. Finally thinking average stress in effective matrix vanish, the residual stress field in Ni base alloy and particles can be gotten by considering random orientation of two-phases models. It will exert influence on strength and fatigue life of the composite coating.

Thermal Expansion Coefficient of Ni Base Alloy Composite Coating Containing Spheroidal Ceramic Grains

“…Because the thermal expansion coefficients and elastic modulus of Ni base alloy and spheroidal ceramic grains are different, there will be residual stresses in both ceramic grains and Ni base alloy in fabricating process. The three-phase model [5] is used to study the residual stresses in both ceramic particles and Ni base alloy in fabricating process. The spheroidal matrix shell is around a spheroidal ceramic grain to form two-phases cell, then the two phases cell with random orientation will be put in effective medium that has average performance of Ni base alloy ceramic composite coating containing spheroidal ceramic grains, as shown in Fig.…”