Effect of Different Contents of WC on Microstructure and Properties of NiCrMo Coatings Prepared by PTA

Abstract

During the service process of the mechanized fishing boat, its low carbon steel hull and parts are extremely susceptible to Cl− erosion and seawater scouring, which cause a decrease in strength and lead to failure. To increase its service life and reduce maintenance costs, coating protection technology is widely used. In order to solve the problem of poor adhesion between paint coating and substrate and low strength of metal coating, NiCrMo-WC coatings with different WC contents (0 wt.%, 5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%) were prepared on the surface of Q235 substrate by plasma cladding technology. The coatings were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), energy spectrum analysis (EDS), etc. Its phase formation rule, microstructure and element distribution were studied. Microhardness test and electrochemical corrosion test were carried out. The study found that the 20 WC coating has the highest average hardness (563.1 HV). It is about 3.25 times of the Q235 substrate. It has the lowest friction, wear rate and lower friction coefficient, showing the best wear resistance. The 15 WC coating has the lowest self-corrosion current density (3.4934 × 10−7 A/cm2) and the lowest corrosion rate (0.0041 mm/a), which is only 3.7% of the corrosion rate of Q235 steel.