Abstract: 5wt% CNTs/Al₂O₃-TiO₂ coatings were prepared by micro-plasmaspraying. Microstructure and high temperature properties of CNTs/Al₂O₃-TiO₂ composite coatings were studied. Its microstructure was dense and the porosity was low. CNTs were dispersed uniformly in CNTs/Al₂O₃-TiO₂ composite coating. In the thermal oxidation processfrom 20℃ to 700℃, the initial weight loss temperature of CNTs was 471.29℃. Theinitial weight loss temperature of CNTs/Al₂O₃-TiO₂ composite coating was raised to 507.8℃. The plasma heating process improved the graphite phase transformation of CNTs,which was helpful for the improvement of initial weight loss temperature of CNTs/Al₂O₃-TiO₂ composite coating. When CNTs/Al₂O₃-TiO₂ composite coating was heated to 300℃, and the high temperature reflectivity was measured at 2-18 GHz, the minimum reflection losswas -7.86 dB at 25 ℃. With increasing temperature, the reflectivity peak continuously decreased and the resonant frequency moved to the low frequency. The experimental reflectivity peak was -12.88dB, and the frequency band width for less than -5dB was 4.48 GHz at 300℃. There sults suggests that CNTs/Al₂O₃-TiO₂ coating is agood candidate for high-temperature microwave-absorbing material.

Key words: micro-plasmaspraying, CNTs/Al₂O₃-TiO₂, high temperature performance, electromagneticproperty