Microstructure and Wear Performance of Ni-Based Laser Cladded Coatings Reinforced with Different ZrC Contents on Structural Steel

To address surface scratching and wear failure of 45 steel piston rods under high-stress service conditions, Ni60A composite coatings reinforced with different zirconium carbide (ZrC) contents (30 wt%, 40 wt%, and 50 wt%) were prepared on 45 steel substrates via laser cladding. The microstructure, phase constituents, microhardness, and wear resistance of the coatings were systematically characterized using XRD, FE-SEM, microhardness tests, and ball-on-disk wear experiments. The results indicated that the composite coatings mainly consisted of γ-(Fe, Ni), ZrC, Cr2C, and FeNi. The microstructure consisted of a dendritic γ-(Fe, Ni) matrix, interdendritic eutectics, and the ZrC second phase. The ZrC phase exhibited multiple morphologies: dendrites, coarse blocks, and fine particles. The 50 wt% ZrC coating achieved a maximum average hardness of 573.62 ± 82.36 HV0.2, approximately 2.49 times that of the substrate. Meanwhile, the 40 wt% ZrC coating exhibited the optimal wear resistance, with a wear volume of only 1.83% of 45 steel. The ZrC-reinforced laser cladded coatings effectively improve surface hardness and wear resistance, providing excellent application potential for piston rod surface strengthening.