Oxidation resistance of a SiC–ZrB2 coating prepared by a novel pack cementation on SiC-coated graphite
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In this study, a functionally graded SiC layer was prepared on a graphite substrate by a pack cementation method with Si, C, and Al2O3 powders. Then a SiC–ZrB2 coating was developed by an in situ reaction method through a novel pack cementation technique at 1873 K with Zr, Si, and B4C powders to improve the oxidation protection ability of SiC-coated graphite. The phase compositions, microstructure, and element distribution of the coating were identified by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy, respectively. The isothermal oxidation test of the coated samples was accomplished at 1773 K in air for 10 h. According to the results, a 550-μm thick graded C–SiC layer was detected at the graphite–coating interface and a SiC–ZrB2 coating was formed on the first coating. The SiC–ZrB2 coating could efficiently enhance oxidation resistance of graphite with a mass gain of +1.1 %, as compared with a −1.2 % mass loss of the first step coating. The excellent protection ability of SiC–ZrB2 coating could be ascribed to the high thermally stable ZrSiO4.
KeywordsB2O3 Oxidation Resistance Coated Sample ZrSiO4 Graphite Substrate
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Conflict of Interest
The authors declare that they have no conflict of interest.
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