Microstructure and Ablation Resistance of ZrC Coating Prepared by Atmospheric Plasma Spraying (APS) and Solid Shielding/ Shrouded Plasma Spraying (SSPS) Methods on SiC-Coated Graphite

In this paper ZrC coating was prepared on SiC coated graphite as a substrate by atmospheric plasma spray (APS) and solid shielding/ shrouded plasma spray (SSPS) methods. Microstructure observation and phase identification of the coatings were performed by scanning electron microscopy and X-ray diffraction. The ablation behavior of the coating was evaluated under supersonic flame for 60s. The results showed that the ZrC coating enhance the ablation resistance of SiC coated graphite remarkably. The results of ablation test revealed that the linear and mass ablation rates of the ZrC coating applied by APS method were 3.7×10-3 mm.s-1 and 22×10-3 g.s-1, while those for SSPS coating were 2.2×10-3 mm.s-1 and 14×10-3 g.s-1, respectively. The excellent ablation resistance is attributed to the formation of continuous zirconia (ZrO2) layer on the surface during the oxidation of the ZrC coating. Moreover, the SPS-ZrC coated sample with lowest pores and cracks have better ablation resistance during the ablation test and can protected the graphite substrate against ablation sufficiently.