Abstract:
TC4 titanium alloy oil drill pipes often encounter the interactive effects of seawater corrosion and mechanical wear in marine environments, significantly shortening their service life. To address this issue, this study employed laser cladding technology to fabricate a graphite/TiCrNiCuNb high-entropy alloy (HEA) composite coating on the surface of TC4 titanium alloy. Through systematic analysis of the coating's microstructure, hardness, electrochemical corrosion, and corrosion-wear properties, it was found that the addition of graphite not only retained the base FCC phase but also promoted the in-situ formation of carbides and intermetallic compounds. Compared with TC4, the coating's hardness was increased by up to 143.77%. In a simulated seawater environment, the C2 coating containing 15at.% graphite exhibited excellent corrosion resistance, with an I
corr as low as 0.93×10
−7 A/cm
2 and an Rs of 1.95×10
6 Ω·cm
2. During corrosion-wear coupling tests, the self-healing passive film formed on the coating surface effectively enhanced its corrosion-wear resistance. The wear rate of the C2 coating was reduced by three orders of magnitude compared to the substrate. This study combines the lubricating properties of graphite, the passivation effect of HEA, and the carbide reinforcement phase in the coating, enabling the coating to simultaneously resist mechanical wear and chemical corrosion. It provides new insights for the application of TC4 titanium alloy in harsh environments such as marine equipment and chemical reactors, and offers theoretical guidance for the composition design and structural optimization of wear-resistant and corrosion-resistant functional coatings.