Thermal cycling and oxidation resistance of B modified ZrB2-SiC coatings on SiC coated graphite

To protect graphite matrix from oxidation, B modified ZrB2-SiC coatings were prepared on SiC coated graphite by a two-step pack cementation. The microstructure, thermal cycling and oxidation resistant properties of the coatings were studied. The results show that the as-prepared coatings were mainly composed of SiC, ZrB2 and Si. ZS50-1B, ZS50-3B and ZS50-5B showed good thermal cycling resistance with 97.4%, 98.2% and 98.6% weight retention after 15 thermal cycles between 1500 °C and room temperature. ZS50-7B and ZS50-9B showed good oxidation resistance with 93.5% and 97.5% weight retention after 19 h oxidation at 1500 °C.