Investigation of ablation resistance of SiC/ZrB2 multilayer graded coating produced by argon shrouded plasma spray method under propane flame

In this research oxyacetylene ablation behavior of SiC/ZrB2 multilayer coating prepared on graphite by infiltration and plasma spray method was investigated. SiC inner layer was prepared on graphite substrate by infiltration method in Si, C and Al2O3 powder bed at 1600°C under argon atmosphere. Microstructural characterization confirmed the formation of SiC graded coating with average thickness of 600μm. ZrB2 outer layer coating was prepared on SiC coated graphite via shrouded plasma spray. Microstructural characterization of ZrB2 outer layer showed that the mechanical bonding is created at the coating-substrate interface without any crack and discontinuity. The results of oxyacetylene ablation test revealed the good ablation resistance of SiC/ZrB2 coated graphite. Mass ablation rate for coated sample was 0.0393 × 10-3 g.cm-2.s-1. This is attributed to the formation of ZrO2-SiO2 protective film on the surface.