Research On Residual Stress Of NiCrAl Coating Based On TA-15 Titanium Alloy Substrate

With the rapid development of aerospace engineering,the surface protection of aeroengine parts has been applied more and more widely,and the thermal spraying technology is becoming more and more important in the surface protection technology of the parts.However,the coating is often accompanied with failure behavior during the service period,such as cracks,warping,cracking and so on.It is found that the residual stress of coating and the substrate easily lead to the failure behavior under the working conditions and seriously affect the service life span and safety of the parts.Therefore,the study of the factors affecting the residual stress in the coating plays an important role in the protection of the parts.This paper focuses on the use of blind hole method to detect different coating system of plasma spray coating by using portable residual stress detector.In the first group,three kinds of TA-15 titanium alloy substrates were measured and the effects of different sand blasting processes on the residual stress were analyzed.The second group of experiments measured the residual stress of NiCrAl-TA15 and Ni CrAl-TC4 coating systems with different thicknesses,and analyzed the distribution of residual stress distance edge.The third group of experiments measured the residual stress of NiCrAl-TA15 coating system sprayed by different enthalpy processes and studied the influencing factors.In addition,this paper also simulates the process of coating spraying,using the finite element software ANSYS to simulate the growth process of the coating by using the method of birth and death,and analyzes the residual stress.Through the analysis of the measured results,it is found that the blasting process changes the surface residual stress state of the titanium alloy substrate,introduces the residual compressive stress field,changes the surface topography of the titanium alloy substrate,and enhances the roughness.The high enthalpy process of plasma spraying has more residual stress than that of the low enthalpy process spraying coating.The distribution of residual stress in the coating is relatively flat in the central region,while there is a significant increase in stress when approaching the edge,resulting in a singular phenomenon of edge stress concentration.The distribution of residual stress in the center region of the coating is relatively gentle,while there is a significant increase of stress when approaching to the edge,and the singular phenomenon of the marginal stress concentration appears,while the residual stress increases with the increase of the thickness of the coating and the tendency of the stress to the tensile stress.By comparing the results of FEM simulation with the test results,the correctness of the test regularity is testified and analyzed.