Corrosion and wear behaviour of HVOF spraying WC-12% Ni coating on gray cast-iron

The coatings produced with high-velocity oxygen fuel spraying technology can greatly improve wear and corrosionresistance. In this study, WC-12% Ni coating was applied on the lamellar graphite cast iron substrate. Morphologies andstructures of uncoated samples and sprayed coatings were analyzed with light microscopy, scanning electron microscope,energy dispersive spectrometry and X-ray diffraction. Although their micro-hardness, porosity, abrasion and corrosionproperties were studied, wear experiments were performed at normal atmospheric conditions (under room temperature and30% humidity) in the reciprocating wear testing machine. The corrosion resistance of the coatings was measured usingpotentio-dynamic polarization. The results revealed that the microstructure was porous, had micro-cracks, and containedsome inhomogeneous structures such as carbide. Energy dispersive spectrometry analysis revealed that the presence ofphases indicated the success in coating process. It was found that the WC-12% Ni coating exhibited lower potential andlower corrosion current density compared to those of the uncoated sample.