High Temperature Performanceof Micro―plasma Sprayed CNTs÷Al2O3―TiO2Composite Coating

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.