Effect of elements diffusion behavior on thermal fatigue of nickel based alloy coating deposited with thermal spraying

Thermal spraying technique was applied to produce nickel based alloy coating on Cu alloy. Optical microscope, SEM analysis were used to investigate the elemental diffusion and the microstructure in the interface between the nickel based alloy coating and the substrate. And the influence of the elements diffusion behavior on thermal fatigue resistance was studied. The results show that alloy elements distribute continuously from nickel based alloy coating to substrate, and have an abrupt change at the interface between the substrate and coating. During heat treatment, an inter-diffusion layer appears between the substrate and coating, and the ability of Cu element diffusion was improved with the increase of temperature and time. The main affecting factor was temperature, and the effect of time was followed during heat treatment. The thermal fatigue resistance of nickel based alloy coating was improved by elements diffusion. The thermal spraying coating endured 85 time thermal shock at 550C was perfect without defects such as crack and spalling.