Effect of La2O3 on Microstructure, Wear Resistance and Corrosion Resistance of Laser Cladded WC-Fe Coatings

Abstract

40CrNiMoA alloy is widely used in key components of energy equipment, but it is prone to wear, corrosion, and other forms of degradation in dusty and humid environments. To solve this issue, this study employed laser cladding technology, incorporating La₂O₃ into a WC-reinforced Fe-based composite coating to enhance the surface performance of the alloy. By adjusting the La₂O₃ content, the impact of La₂O₃ on the coating’s phase composition, microstructure, microhardness, and wear and corrosion resistance was investigated. The findings indicated that adding a suitable amount of La₂O₃ increased the wetting angle of the single-pass coating and reduced pore number by improving coating fluidity. The coating primarily consisted of α-Fe, γ-Fe, M_xC_y, and La₂O₃ addition contributed to grain refinement. When the La₂O₃ content was 1 wt.%, the coating exhibited a maximum average hardness of 544.25 HV_0.2, representing a 20.43% increase in relation to that achieved by the coating without La₂O₃. Furthermore, its wear resistance was significantly improved, with the specific wear rate loss reduced by 32.6 %, with the wear mechanism dominated by mild adhesive and abrasive wear. Notably, La₂O₃-induced grain refinement effectively hindered Cl⁻ penetration, thereby endowing the composite coating with excellent corrosion resistance.