Study on tribological properties of Ni-based silicide coating on copper by laser cladding

Two Ni-Cr-Si coatings of Cr3Si+γNi (45Ni-26Cr-29Si) and Ni16Cr6Si7+Ni2Si (60Ni-10Cr-30Si) (atomic fraction, %) are synthesized on pure copper using laser cladding. The microstructures of the coatings are analyzed by optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). The wear resistance of the coatings is evaluated under ambient temperature. The results show that due to the different crystallization temperature ranges between binary phase and ternary phase, constitutional supercooling degrees are different in the process of crystallization and different microstructures are formed. The coating consisted of Cr3Si+γNi has an average hardness of 1000 HV and the friction coefficient of 0.5, but 4 cracks appear to the corner of indentation when loads add to 500 g. The coating consisted of Ni16Cr6Si7+Ni2Si with an average hardness of 900 HV, fine toughness of no cracks generating under loads of 1000 g, an average friction coefficient of 0.5 has good comprehensive performance than that of the coating consisted of Cr3Si+γNi. ©, 2015, Science Press. All right reserved.