Comparative study of anti-corrosion properties in different CrN/WC-Co duplex coatings processed by PVD/HVOF

WC-Co coatings produced by high-velocity oxy-fuel (HVOF) show the high porosity which limits their application in seawater. Herein, we prepared CrN/WC-12Co and CrN/WC-10Co-4Cr duplex coatings combined with the physical vapor deposition (PVD) and HVOF technologies. The microstructure and the corrosion behavior were studied and compared with WC-Co coatings. The CrN film covers the pores on the surface of WC-Co coatings which enhances the corrosion resistance. In addition, the corrosion products of WC-10Co-4Cr coating seal the defects in the CrN film, and further improve the corrosion resistance of the duplex coatings. The CrN/WC-Co duplex coatings enhance the corrosion resistance of WC-Co coatings, especially for CrN/WC-10Co-4Cr, which greatly increases the corrosion potential and reduces the corrosion current density of WC-Co coatings.