Refractory ceramic WC reinforced Co matrix composite coatings on IN718 superalloy: microstructure, wear mechanisms and surface energy

WC micro-particles reinforced Co matrix composite coatings were fabricated by laser cladding in this work. Their microstructure, wear mechanisms and surface energy were investigated. The results show that the improved hardness (501.78-586.7HV0.5) was mainly attributed to the formation of carbides and intermetallic compounds. Compared to the substrate, an order of magnitude improvement (1.44, 1.16 and 0.65× 10-5mm3/N·m) in wear resistance was obtained in the composite coatings at RT, the COF decreased by 33.5%. The wear mechanism of the composite coatings at 600 ℃ changes from abrasive and adhesive wear to oxidation wear, COF and wear rate were reduced by 32.4% and 57.3%, respectively. The surface energy (29.40mN/m) of the Co-5wt.%WC coating is the lowest, which is one of the reasons for its excellent tribological performance.