Study Of Gradient Thermal Barrier Coatings On Aluminum Substrate

In order to use thermal barrier coatings on the top of aluminum piston in low heat emission engine , a gradient thermal barrier coatings (TBCs) is designed and fabricated with plasma spraying on aluminum substrate . Its microstructure and property is investigated . And its thermal barrier property is estimated by the testing apparatus which is designed and installed .NiCrCoAlY and ZrO2 with 8wt%Y2O3 are chosen to fabricate the gradient TBCs . Hot shock and draw experimental results indicate the TBCs has a high bond strength . SEM(scanning electron microscope) and metallographical picture show the best coatings can be obtained and the micro-interface between NiCrCoAlY and ZrO2 which exists in duplex coating is eliminated. Structure analysis by XRD(X-ray diffraction) demonstrate types of phases for peel-off coatings are t-ZrO2 , Ni-based solid solution and A12O3 . The testing apparatus can estimate the thermal property of the coatings effectively . The layers whose ZrO2 content is above 50% is more important then others for heat insulation function .