Effect of Cr3C2 distribution on the wear and corrosion properties of HVOF-sprayed WC–12Co/Cr3C2–25NiCr composite coatings

Abstract

In this study, experimental ball-milling mixed feedstock powder (BMP) and spray-drying feedstock powder (SDP) were prepared, and the WC–12Co/Cr3C2–25NiCr coatings were sprayed with high-velocity oxygen fuel (HVOF). The microstructures, phase compositions, as well as wear and corrosion resistance of the two coatings were explored. The results indicated that SDP at a 250 °C inlet temperature and 2 wt% binder had a uniform elemental distribution, excellent fluidity, and apparent density. The SDP coating was also more uniform and denser than the SMP coating. In addition, an amorphous phase formed in the SDP coating during the HVOF process. The SDP coating exhibited a uniform microstructure, better wear property, and wear rate of 5.5 × 10−14 m3/(N∙m), which is 29% lower than that of the BMP coating. Furthermore, the SDP coating showed superior corrosion resistance in a 36 wt% HCl solution, with a corrosion current of about 2.26 × 10−3 A∙cm−2 and corrosion rate of 26.57 mm/a, which is 81.8% lower than that of the BMP coating. The molecular dynamics simulation indicated that the uniform distribution of Cr3C2–25NiCr substantially reduced the adsorption energy of HCl for WC–12Co.