Microstructure and Wear Behavior of Hard Ni60 and Soft WC-12Co/N125 Coatings Prepared by Laser Cladding on W1813N Non-magnetic Stainless Steel

The hard Ni60 (60HRC) self-fluxing alloy powder and soft Ni25-based WC-12Co composite powder were separately deposited onto the W1813N non-magnetic stainless steel using laser cladding (LC). The microstructure, phase composition and worn track characteristics of the Ni60 coating and WC-12Co/Ni25 composite coating were analyzed using scanning electron microscopy (SEM), energy dispersive spectrum (EDS), X-ray diffraction (XRD) and a step profiler. The micro-hardness, friction coefficient, profile of worn track and wear mechanism of both coatings were investigated. The results show that the microstructure is mainly fine dendrite and equiaxed crystal in the LC Ni60 coating, and the hard Cr23C6 and Cr2B phases are distributed in the grain boundary of gamma-Ni and FeNi solid solution, while WC-12Co particles in the composite coating are uniformly embedded in the Ni25 matrix, and the volume fraction of WC-12Co in the composite coating is 32.5 vol%. The difference value between minimum and maximum hardness in the WC-12Co/Ni25 composite coating reaches 6480 MPa. Although the mean friction coefficients of both coatings are similar, the volume loss of the LC WC-12Co/Ni25 is only 10% of that of the LC Ni60. The surface abrasive behaviors of the LC Ni60 coating are ploughed shape and adhesive scraps, but the surface abrasive behaviors of the LC WC-12Co/Ni25 composite coating are adhesive scraps and WC debris. The wear mechanism of the Ni60 coating is abrasive wear and adhesive wear, while the wear mechanism of the WC-12Co/Ni25 coating is adhesive wear. These demonstrate that the WC-12Co/Ni25 coating exhibits better wear resistance than the LC Ni60.