The influence of substrate morphology on the thermal radiation properties of SiC coating

SiC coating was prepared on the graphite substrate and the effects of substrate morphology on the thermal radiation properties of SiC coating were investigated. As the surface roughness of the graphite substrate decreasing from 2.95 to 0.68 μm, the total emissivity of SiC coating increased 28.33% at 1000 °C and 36.21% at 1600 °C, respectively. At the same time, the spectral emissivity of SiC coating on the graphite substrate all presented the obvious characteristic thermal radiation of SiC. Those results meant that the thermal radiation properties of the coating were both dominated by the substrate and coating. A simple coating model had been established to explain the effect of the substrate morphology on the heat flow between the substrate and coating. The rough substrate morphology enhanced the energy dissipation at interface and weakened the thermal radiation properties of coating finally.