Tribological Properties of Laser Cladding Co-Based Alloy Coating Under Different Loads

Laser cladding technology was used to prepare a Co-based alloy coating on a GCr15 bearing steel substrate. The microstructure, microhardness, and dry friction of the coating, and wear experiments were performed using various loads. The results show that the microstructure is in the form of plane, columnar, dendrite, and equiaxed crystals from the bottom to the top of the cladding layer. This is due to the solid solution strengthening of alloy elements, dispersion strengthening of carbide hard phase, and fine grain strengthening of microstructure, and the average microhardness of the coating is approximately 1.36 times higher than that of GCr15 bearing steel. With the increase of external load, the average friction coefficient of the laser cladding layer is increased, the friction coefficient decreases from 0.342 to 0.261, and the fluctuation amplitude decreases gradually, while the wear rate increases to 27.93 x 10(-2) mm(3).N-1.m(-1). The wear mechanism of the coating varies with the load. The coating wears primarily due to abrasive wear and minor oxidation wear under a 150 N load. When the load increases to 300 N, the coating primarily wears due to oxidation and adhesive wear. For a 450 N load, the worn form of the coating is primarily due to microcutting and strong plastic deformation, with a smooth and flattening wear surface due to the formation of stable oxide enamel and work hardening layers.