High Temperature Resistance of Thermal Barrier Coating on Magnesium Alloy Surface

Abstract

Thermal barrier coatings were prepared on magnesium alloy substrate by plasma spraying, and thermal shock test, thermal shock test and arc wind tunnel test were carried out. The failure mode, microstructure and phase transition of thermal barrier coating after thermal shock and thermal shock test were analyzed by SEM and XRD The change of temperature rise rate during wind tunnel test is analyzed by means of temperature measurement. The analysis results show that the phase structure of thermal barrier coating sprayed on magnesium alloy surface is consistent before and after thermal shock, and no phase transition occurs during spraying and after thermal shock. The failure of coating is mainly due to the different thermal expansion coefficients, which aggravates the thermal stress between layers, and leads to the lower and lower bonding strength of coating, and finally spalling. Spraying thermal barrier coating on the surface of magnesium alloy has a good heat insulation effect, and the heating rate is significantly reduced. The heating rate of the back surface of VW75 magnesium alloy matrix sample is 0.8 °C/s. After spraying thermal barrier coating, the heating rate of the back surface of coated sample is reduced to 0.39 °C/s, and the heating rate is reduced by about 50%. After the wind tunnel test, the adhesion between the coating and the substrate is good, and there is no bulge or falling off, which shows that the coating has good adhesion and can meet the future service working environment and working requirements, and the calculation results of thermal conductivity have a good corresponding relationship with the temperature rise rate in the wind tunnel test.