Effect of multilayer laser cladding on the microstructure and wear resistance of SiC/Ni60A coatings

Abstract A fiber laser was used to perform multiple laser cladding passes on AISI 1045 steel to fabricate SiC particle-reinforced Ni60A alloy coatings. The microstructure and phase composition of the cladding layers were analyzed using optical microscopy, X-ray diffraction scanning electron microscopy and energy-dispersive spectroscopy. The microhardness and wear performance of coatings with different numbers of cladding layers were tested using a microhardness tester and a wear testing machine. The results show that the SiC/Ni60A composite coating, prepared by synchronously adding 20% SiC to a Ni60A matrix during laser cladding, is primarily composed of phases such as FeN3, Gr0.19Fe0.7Ni0.11, Gr23C6, and Ni31Si12.In the single-layer cladding coating, blocky crystals dominate the microstructure, whereas dendritic structures are predominant in the double- and triple-layer coatings. At the interface between the first and second layers of the four-layer coating, the maximum tensile stress reaches 350 MPa. As the number of coating layers increases, the number of cracks and pores increases, while the average microhardness and wear resistance decrease. For repairing components with deep damage (greater than 0.5 mm), two- or three-layer cladding should be employed, resulting in a coating thickness of approximately 1.5–2.5 mm.For the two-layer SiC/Ni60A composite coating, the average microhardness of the cladding layer is 962 HV, 4.3 times that of the AISI 1045 steel substrate. When using two-layer laser cladding, the relative wear of the cladding layer reaches 0.0018 g, and the wear resistance at this time is 4.7 times that of the substrate. The primary wear mechanism of the multilayer SiC/Ni60A cladding is adhesive wear, accompanied by abrasive wear.