Corrosion behaviour of WC-Ni high velocity oxy-fuel (HVOF) coating with the influence of spraying parameter

Abstract

The high-velocity gas stream produces by high-pressure combustion in high velocity oxy-fuel (HVOF) both melts and propels the powder particles toward the substrate to be coated. It is one of the most popular deposition methods that may produce dense coating with superior abrasion and corrosion properties. In HVOF, the oxygen gas flow rate influence the coating microstructure, which affects the corrosion behaviour of the coating. Therefore, corrosion behaviour investigation of the coatings with the influence of spraying parameters and its mechanism is significant. Carbon steel AISI 1040 was coated using HVOF process. Tungsten carbide nickel (WC-10Ni) was used as the feedstock powder or coating material with particle size of 45 ± 11 µm. HVOF coating was performed at different flow rate of oxygen gas which were 30, 45 and 60 L.p.m (liquid per minute). The morphology and chemical composition of the HVOF coating were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). The electrochemical test was carried out in 3 wt% sodium chloride (NaCl) electrolyte. The corrosion behaviour of the prepared coating were tested at the range of −0.25 to 0.25 V and −0.25 to 0.75 V for initial and final potential voltage, respectively. The influence of oxygen flow rates has been analysed in term of corrosion behaviour. The corrosion resistance of the coating prepared at 30 L.p.m oxygen showed highest positive current density −200.90 mV as compared to other coatings.