Investigation on Sliding Tribological Properties of Laser Cladding Alloy Coating for Subway Wheels

Abstract

The wheel pair is a key component of the subway. Routes of subway conditions are more complex, while frequent starting and braking are more likely to cause wheel damage. To improve the sliding tribological properties of subway wheels, this article focused on laser-cladding technology to repair the wheel. Ni-based and Fe-based alloy coatings were prepared. The microstructure of the coatings was studied by SEM, EDS, XRD, and 3D optical morphology. The mechanical properties of the coating were studied by the Vickers microhardness tester and MFT-EC4000 reciprocating electrochemical friction and wear tester. There are mainly γ(Ni, Fe), Cr7C3, Cr23C6, and other phases in the Ni-based coating, and there are mainly γ-Fe, (Fe, Ni), (Fe-Cr-Ni) solid solution and other phases in the Fe-based coating. The hardness of the Ni-based coating is 250 HV0.7, which is essentially the same as the hardness of the substrate. The hardness of the Fe-based coating reaches a maximum of 715HV0.7. The hardness of the Fe-based coating is 2.86 times higher than the hardness of the substrate. The Fe-based coating is strengthened by the solid solution due to the existence of the solid-solution phase. The Ni-based coating in high-temperature performance is general. Its hardness and friction performance were also ordinary. The results of the study can provide theoretical and technical guidance for the application of laser-cladding technology on subway wheels.