Microstructure and electrochemical properties of nanostructured WC-10Co-4Cr coating prepared by HVOF spraying

摘要

A nanostructured WC-10Co-4Cr coating was deposited on the substrate of AISI 1045 steel by means of highvelocity oxygen-fuel (HVOF) thermal spraying process. The detailed microstructures and phase composition of the coating were analyzed by using X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), differential scanning calorimeter (DSC) and high-resolution transmission electron microscope (HRTEM). It was revealed that the amorphous phase, nanoclusters and carbides, including W_2C and WC were present in the coating. The coating with low porosity of 0.85% had a dense structure and good thermostability. The temperature of the amorphous phase transforming into the nanocrystalline structure was 645 °C. Corrosion behavior of the coatings was investigated by electrochemical measurement. The results showed that the coating exhibited better corrosion resistance than the hard chromium coating in 3.5 wt.% NaCl solution.