HPPS制备SiC陶瓷涂层组织特征及抗烧蚀性能

A SiC coating was deposited by high power plasma spraying (HPPS) on carbon/carbon (C/C) composites. Three sets of parameters were selected to optimize the properties of the coating. The anti-ablation property of the SiC coating was investigated by oxyacetylene torch flame at 1500℃. The phase composition, microstructure and component of coatings were analyzed by different methods including X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. The results show that the porosity of three sets of coatings is 21.3%, 17.4% and 15.3%. The plasma jet field has a more suitable temperature field and velocity field under the condition that the main gas flow is relatively high and the auxiliary gas flow is low. SiC powders are heated more fully to achieve better melting state and obtain larger kinetic energy. Therefore, the deposition rate of the coating increases gradually and the porosity decreases gradually. SiC powders are oxidized to form amorphous SiO ₂ . After having been ablated for 300 s, the SiC coating provides effective protection for the matrix. Because of the temperature gradient caused by the oxyacetylene on the surface of the sample, the coating forms three kinds of ablation morphology after ablation, including a central dense area, a transition area and a edge loose area. During the ablation, a dense SiO ₂ glass layer is generated on the surface of central area coating, which is beneficial to blocking the infiltration of oxygen.