Effect of La2O3 on hardness, wear resistance and corrosion resistance of WC/Fe90 iron-based composite coatings

In this paper, WC/Fe90 iron-based composite coatings were prepared using plasma spraying technology. The influence of rare earth oxide La ₂O ₃ on the microstructure and properties of the composite coatings was studied through microstructural characterization, phase identification, microhardness, wear resistance, and corrosion resistance. The results showed that the composite coatings were mainly composed of α-Fe, M ₇C ₃, Fe-Cr, Fe _xC _y, and other reinforcing phases. The addition of La ₂O ₃ promoted the decomposition of WC particles and improved the uniformity of the coatings. When the La ₂O ₃ content reached 1.0 wt%, the hardness was the highest, reaching 885.481 HV, which was 10% higher than that of the untreated coatings. The addition of La ₂O ₃ increased the friction coefficient but still improved the wear resistance. Compared to the coatings without La ₂O ₃, the mass loss due to wear was reduced by approximately 40%. Moreover, the addition of La ₂O ₃ formed a passive film on the surface of the coatings, effectively preventing the penetration of Cl ^- ions and refining the grain structure of the coatings, significantly enhancing the corrosion resistance. When the La ₂O ₃ content was 1.0 wt%, the corrosion resistance of the coatings was the best.