Wear Resistance of Laser Cladding TiC Particle-Reinforced Fe-based Gradient Coating

Abstract:

A high-hardness, wear-resistant gradient ceramic coating was prepared by laser cladding TiC particle-reinforced iron-based powder onto a 40Cr steel substrate to achieve the coating's gradient effect. Scanning electron microscope (SEM), energy dispersive spectroscope (EDS), X-ray diffractometer (XRD), micro-hardness tester, and friction and wear tester were used to investigate the microstructure, phase, hardness, and wear resistance of the cladding layer. Results show that the phase of the cladding layer is mostly austenite, some TiC strengthening phase, and a trace amount of ferrite phase. The cermet coating made of laser cladding TiC particle-reinforced powder has a compact microstructure, and the coating phase composition is essentially the same as the powder composition. The TiC phase, which is responsible for the strengthening effect, is dispersed across the molten pool following a gradient from the bottom to the top. The TiC phase reinforcing the molten pool is partly dissolved, and thus the size of the pool shrinks. Under the laser's intense heat, some TiC strengthening phases develop into shapes like squares, snowflakes, and fish bones. At the base of the molten pool, the TiC phase may develop in three ways, while the TiC strengthening phase is less widely dispersed. The TiC strengthening phase in the center of the molten pool is progressively expanded, and enriched and bridged in the top portion of the molten pool. The cladding layer has a Vickers hardness HV up to 19 602.94 MPa, and under the same circumstances, the friction and wear depth of the coating is only one-fifth of that of the substrate. This results in a considerable improvement in the wear resistance of the substrate.