Investigation of the microstructure and tribological properties of laser cladding 5%Ti3SiC2 reinforced Co-based composite coatings under different loads over the wide temperature range

In order to improve the mechanical properties of SUS 304 in practical engineering application, Co-5%Ti3SiC2 coating was successfully prepared on SUS 304 by laser technology. The microstructure of Co-5%Ti3SiC2 coating was characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffractometer (XRD) to evaluate the tribological properties in detail. The relevant wear mechanism of the substrate and Co-5%Ti3SiC2 coating under different loads (2, 5 and 8 N) in isothermal tribological experiments (25 and 600 °C) were systematically explored. The results show that the Co-5%Ti3SiC2 coating is mainly composed of continuous matrix γ-Co solid solution, ceramic Fe2C, Cr7C3 and TiC, and lubricating phase Ti3SiC2. The average micro-hardness of Co-5%Ti3SiC2 coating is 358.61 HV0.5, which is significantly higher than that of SUS 304 (239.32 HV0.5). In all isothermal tribological experiments, the wear rate of Co-5%Ti3SiC2 coating decreases with the increase of load, and its coefficient of friction (COF) also decreases with the increase of load. •The Co-Ti3SiC2 composite coatings were successfully prepared on 304 stainless steel by laser cladding.•The MAX phase Ti3SiC2 elevated the wear resistance of composite coatings under different loads over the wide temperature range.•The MAX phase Ti3SiC2 played lubrication and protection roles in the coatings, which improve the tribological properties.•The wear mechanisms were investigated from the morphology of surface and wear affected zone respectively.