Carbon dot/nickel nanocomposite coating for wear and corrosion control of Mg alloy: Experimental and theoretical studies

Due to their self-lubrication and corrosion inhibition properties, carbon dots (CDs) were utilized to endow a nickel coating on a magnesium alloy substrate with superior tribology and anti-corrosion properties. The surface and cross-sectional morphologies confirm that these novel carbon dots remarkably improve the compactness of the nickel coating, leading to much higher hardness and adhesion strength. The carbon dot/nickel coating prepared with 0.5 g/L CDs has a lower wear rate and friction coefficient than the other coatings, demonstrating its excellent self-lubricating performance. Moreover, as demonstrated by electrochemical tests and the formation of corrosion products, this coating exhibits significantly enhanced anti-corrosion performance, with the lowest corrosion current and largest impedance modulus among the prepared coatings. Theoretical calculations confirm that the CDs provide a high energy barrier for the penetrating diffusion of Cl. Thus, the CDs effectively prevent the active penetration of corrosive substances. As a result, the as-prepared carbon dot/nickel nanocomposite coatings can efficiently control the wear and corrosion failures of Mg alloy under some harsh conditions.