Effects of La2O3 mass fraction on microstructure and friction-wear performances of WC-10Co4Cr-Al2O3 coatings by laser cladding

摘要

In order to improve the hardness and wear resistance of cold work molds, La2O3-reinforced WC - 10Co4Cr - Al2O3 coatings were fabricated on Cr12MoV steel by laser cladding (LC). The morphologies, grain sizes, and phases of obtained coatings were analyzed using a digital microscopic system (DMS) and X-ray diffraction (XRD), respectively. The effects of La2O3 mass fraction on the tribological performance and wear mechanism of WC - 10Co4Cr - Al2O3 coatings were analyzed using a ball-on-disk wear tester. The results show that the La2O3-reinforced WC - 10Co4Cr - Al2O3 coatings are composed of WC, W2C, Al2O3, La2O3, LaAlO3, and Fe - Cr, AlP3Si, LaCoO3, and LaP phases, and the hardness of obtained coatings increases with the increase of La2O3 mass fraction. The average coefficients of friction (COFs) of WC - 10Co4Cr - Al2O3 - 3%La2O3, - 6%La2O3, and - 9%La2O3 coatings are 0.57, 0.52, and 0.46, respectively; and the corresponding wear rates are 63.18, 47.1, and 27.99 mu m(3)center dot s(-1)center dot N-1, showing that the friction reduction and wear resistance of WC - 10Co4Cr - Al2O3 - 9%La2O3 coating are the best among the three kinds of coatings, and the grain refinement and dispersion strengthening by the addition of La2O3 are the main factor affecting its wear resistance.