Microstructure and Tribological Performance of Laser-Cladded Mo2C-Reinforced NiMo Coatings Under Grease-Lubrication Condition

NiMo coatings with different Mo2C mass fractions were prepared on GCr15 steel by laser cladding (LC). The microstructure and phases of obtained coatings were analyzed using a ultra-depth of field microscope (UDFM) and x-ray diffraction (XRD), respectively. The effects of Mo2C mass fraction on the coefficient of friction (COF) and wear rate of NiMo-Mo2C coatings under the grease-lubrication condition were investigated using a wear tester, and the wear mechanism was discussed in detail. The results show that the hardness of NiMo-5%Mo2C, -15%Mo2C, and -25%Mo2C coatings is 1120, 1154, and 1189 HV0.5, respectively, which increases with the increase in Mo2C mass fraction. The average coefficient of frictions (COFs) of NiMo-5%Mo2C, -15%Mo2C, and -25%Mo2C coatings is 0.112, 0.135, and 0.128, respectively, and the corresponding wear rates are 22.29, 19.09, and 11.43 mu m(3) s(-1) N-1, respectively, showing that the NiMo-Mo2C coatings enhance with the increase in Mo2C mass fraction. Moreover, the NiMo-25%Mo2C coating presents superior wear resistance, and the wear mechanism is primary abrasive wear.