The graphite has been generally used as a high-temperature structural material. However, graphite can easily react with oxygen even at temperatures as low as 400 °C. The graded silicon carbide (SiC) characterized by compositional gradation over microscopic distances More
The graphite has been generally used as a high-temperature structural material. However, graphite can easily react with oxygen even at temperatures as low as 400 °C. The graded silicon carbide (SiC) characterized by compositional gradation over microscopic distances, is considered to be the most promising coating material in order to prevent the oxidation of graphite. In this paper, SiC coating has been created on five kinds of graphite substrates using a pack cementation method. The relationship between the microstructure and property of graphite substrates and SiC coating was investigated experimentally and theoretically. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis demonstrate that the coating obtained by the pack cementation is a dense structure comprising Si, C and β-SiC. It was found that the kind of graphite has marked effect on the microstructure of SiC coating. SiC gradient coating is expected to form on the surface of graphite with high density, good graphitized, appropriate porosity and the pore radius mainly over the range of 600–710 nm.
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