Microstructure characteristics of silicon carbide coatings fabricated on C/C composites by plasma spraying technology

A functional gradient SiC coating on C/C composites has been developed using a novel process which is the combination of plasma spraying technology with reaction-formed heat-treatment. Microstructure observation and phase identification of the SiC coatings were analyzed by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Experimental results showed that a uniform silicon coating was deposited on C/C composite by plasma spraying technology. The reaction between the silicon coating and C/C substrate occurred during the heat-treatment at temperature of 1450 °C and 1600 °C in argon environment, respectively. A continuous SiC coating was formed on the surface of the C/C substrate. And a layer of SiC/C convention layer was formed on the near-surface area of the substrate, which was resulted from the molten silicon penetrating into the open pores and consequently reacting with the C/C composites. The thickness of the formed SiC coatings was closely related to the original silicon coatings.