Abstract: In order to improve high-temperature electrical insulation of the nickel-based superalloy substrate and improve the reliability of the temperature sensor during the operation of the aero-engine, the amorphous AlON film and the Al2O3 film was sputtered by the DC reactive sputtering, to form the AlON/Al2O3 composite coating. The microstructure of the prepared AlON film was analyzed by XRD and SEM, and the high temperature insulation property of the AlON/Al2O3 composite insulating layer was measured. The results show that the prepared composite coating has good high-temperature insulation property. The resistance reaches 5.6 MΩ at 800℃ and 140 kΩ at 1000℃, which is three orders of magnitude higher than that of the single Al2O3 insulation layer. The preparation of the composite coating is completed at one time during the sputtering process, which significantly improves the quality and preparation efficiency of the insulating layer. This work provides foundation for the reliable operation of the thin film thermocouple on the superalloy substrate.
Keywords: high-temperature insulation; super alloy substrate; amorphous AlON; composite coating; reactive sputtering