Enhancement mechanisms of self-lubricating Ti3SiC2 ceramic doping in CoCrFeNi high-entropy alloy via high-speed laser cladding: Tribology and electrochemical corrosion

High-entropy alloys (HEAs) are renowned for their superior mechanical properties and corrosion resistance, positioning them as promising materials in the realm of wear and corrosion-resistant applications. In this study, CoCrFeNi HEA coatings were fabricated utilizing the high-speed laser cladding (HLC), and the effects of adding Ti3SiC2 self-lubricating phase on the microstructure, wear resistance, and electrochemical corrosion performance of CoCrFeNi HEA coatings was investigated. The results show that CoCrFeNi HEA coatings synthesized via HLC exhibit an impressively low dilution rate of <0.1 %, while concurrently ensuring a robust metallurgical bond with the substrate. CoCrFeNi coating has an FCC simple solid solution structure. Upon the addition of Ti3SiC2, the composite structure comprises FCC, Ti3SiC2, and TiC phases. The friction coefficients (COFs) of CoCrFeNi coating and the coatings with 3, 6, and 9 at.% Ti3SiC2 content are 0.684, 0.628, 0.429, and 0.426, respectively. Predominantly, the wear mechanisms observed encompass abrasive wear, adhesive wear, and oxidative wear. Intriguingly, when the Ti3SiC2 content reaches 6 at.%, a contiguous self-lubricating layer forms within the wear track, leading to a notable reduction in COF and a marked enhancement in wear resistance. In electrochemical corrosion evaluations, the coatings demonstrated polarization resistances of 11,400, 9923, 9654, and 6125 Ω·cm2, respectively. While Ti3SiC2 exhibits commendable passivation capabilities, an elevated Ti3SiC2 content can expedite corrosion processes by fostering a potential difference battery formation on the coating surface.