Formation of carbon composite coatings by plasma spraying

• The carbon–silicon–sulfur composite coatings were prepared by plasma spraying.
• The effect of torch input power on the as-sprayed coatings was investigated.
• Higher torch power reduces the surface roughness and increases the specific surface area of coatings.
• The microhardness values of composite coatings increased with spraying power.

Carbon–silicon–sulfur composite coatings were deposited on stainless steel by atmospheric plasma spraying. The effect of spraying power on the coating microstructure and microhardness was investigated. The surface morphology and elemental composition of as-sprayed coatings were examined by scanning electron microscopy and energy dispersive X-ray spectroscopy. The increase of torch power leads to a lower oxidation degree and reduces the silicon concentration in the coatings. The SEM cross-section measurements indicated that the thicknesses of the coatings were in the range of 10–15 μm. The X-ray diffraction measurements indicated an increase of crystalline graphite phase with the increase of power. The results indicated that the coating roughness decreased, while the microhardness and specific surface area increased with increased power. The highest microhardness value of 314 HV was obtained.