Preparation and Properties of SiC-CNTs/Al2O3-TiO2 Coating

CNTs-SiC/Al2O3-TiO2 coatings were prepared by micro-plasma spraying. Microstructure, high temperature oxidation resistance, complex permittivity and absorbing performance of CNTs-SiC/Al2O3-TiO2 coatings were studied. The coatings were density, low porosity. Little oxidation occurred during the spraying process. The phase of beta-SiC and C were successfully retained during the plasma spraying process. The high temperature oxidation of CNTs-SiC/Al2O3-TiO2 composite coating is improved compared with that of CNTs. The initial weight loss temperature of CNTs-SiC/Al2O3-TiO2 composite coating is raised to 511 degrees C. The weight loss of the sample heated from 35 degrees C to 700 degrees C is 0.71 wt%, while the weight loss of the sample held for 60 min at 700 degrees C is 0.41wt%. The real parts of complex permittivity of the CNTs-SiC/Al2O3-TiO2 composites decrease from 17.3 to 10.3 with the increasing frequency. And with increasing frequency, the real parts of complex permittivity of the composites decrease from 6.3 to 2.9. This tendency is beneficial for the absorption of the microwave with wide frequency band. The CNTs-SiC/Al2O3-TiO2 coatings have ability of absorbing microwave. The microwave absorbing performance of the coating with thickness of 0.9 mm is pure. However, with the increase of the coating thickness, the microwave absorption properties were enhanced and the minimum reflection loss shifts to low frequency with the increase of the coating thickness.