Effect of sub‐layer temperature during HFCVD process on morphology and corrosion behavior of tungsten carbide coating

Abstract WC coating was deposited on the polished and cleaned 316L stainless steel by Hot Filament Chemical Vapor Deposition ( HFCVD ) technique at 400°C and 500°C. Field Emission Gun Scanning Electron Microscope ( FEG ‐ SEM ) was used to study the corrosion morphology of the WC coatings. Energy dispersive spectroscopy ( EDS ) was used to analyze the chemical composition of the coatings. Coating porosity was measured by immersion in water. Potentiodynamic polarization and electrochemical impedance spectroscopy ( EIS ) techniques were used to study the corrosion behavior of the coating in the solution of 1 mol/L H ₂ SO ₄ . Results showed that the WC coatings have a honeycomb microstructure where its porosity was increased at higher temperature of the sub‐layer. Also, the WC coating significantly increases the corrosion resistance of 316L stainless steel. And increasing the sub‐layer temperature in the HFCVD method reduces the corrosion resistance of the WC coating. Corrosion morphology was indicative of pitting corrosion of the WC coating.