Temperature effects on thermal fatigue performance of sprayed coatings on copper substrate and its failure mechanism

Cr3C2-NiCr coating was prepared by plasma spraying technique on CuCo2Be alloy substrate. High temperature thermal shock test were carried out at 500℃,550℃,600℃,650℃. The effect of temperature on the hot and cold fatigue life and failure mechanism of the coating was studied. The characteristic of the formedof phases, coating microstructure and the oxidation behavior after thermal shock failure both inside and outside were detailedly analyzed by XRD, SEM, EDS etc.The result showed that coatings present obvious layered structure while Cr3C2-NiCr compounds are angular. The EDS analysis of various phase and elements distribution, indicated that the combination of coating and interface is mainly mechanical bonding. Through XRD analysis it is found that coating has amorphous phase. The main part of the coating is made of copper, nickel oxide after thermal shock failure. The main failure mechanism of the high temperature thermal shock is the combination of thermal mismatched stress of and the oxidation o. Along with the thermal shock test temperature gradually increased from 550℃ to 650℃, the stress between coating and substrate was gradually increased,and the oxidation of copper alloy matrix was intensified.