Experimental Study And FEM Analysis For Bond Strength Of Thermal Sprayed Coating

The bond strength of thermal sprayed coating is an important part for evaluating the quality of coating. In order to improve the strength of coating, an annular nozzle with six holes was designed and the electric stove with protected atmosphere was reconstructed, post-processing of sintering had been put forward. Then the binding of the interface between coating and substrate was improved evidently.The interfacial microstructure of coating/substrate was studied by OM and SEM. The results show that the coating with good bonding properties was synthesized by means of post treatment of sintering. Composition distributions of Fe, Ni, Al on the interface of Ni-Al mixed thermal sprayed layer formed by median temperature reactive sintering were studied by SEM. The results show that diffusion is not the only cause of the interfacial bond, the non-equilibrium evolution of the interface could promote the healing of the interface.First, a wedged load test method was used to evalute the adhesion strength of hard coatings. Then an improved test method was used to evaluate the bond strength of high-strength coatings. In this test, symmetrical wedged cuts or deep U cuts were cut along the interface of the coating/substrate exactly by wire cutting, then the two free sides which were parallel to the interface were adhered and undrawed by tensile force along the interface of the coating/substrate. The bond strength of thermal sprayed coating formed by sintering which with high-strength was studied by expriment. Then the average stress of connecting parts of coating/substrate was gotten when the coating was destroyed.In order to get a precise evaluation of coating/substrate bonding strength, the stress distributions on the coating/substrate interface and the stress concentration of the crack tip...