Study on the microstructure and insulation properties of plasma-sprayed alumina coatings

Abstract This study aims to investigate the microstructure and insulating properties of plasma-sprayed alumina coatings. Alumina is widely used in wear-resistant and corrosion-resistant applications due to its high hardness. The application of alumina insulating coating in electric vehicle PTC heaters not only improves the safety and efficiency of the heaters but also extends their service life, which is of great significance to the overall performance and reliability of electric vehicles. By employing a cascaded plasma spray gun, a dense and uniformly distributed alumina coating was successfully prepared. The microhardness test results of the coating showed a value of up to 907 HV0.3, indicating good wear resistance. Additionally, this study focused on the insulating properties of the coating and found that under optimized process parameters, the breakdown voltage reached 4840 V when the coating thickness was 300 µm, demonstrating the excellent electrical insulating performance of the coating.