Modification of Mg/Al-LDH by vanadate: effects on tribological properties and corrosion resistance

In this study, Mg/Al layered double hydroxide (LDH) composite coatings were prepared on the surface of anodized 1060 aluminum alloy by an in situ growth method, and then the vanadate anions were embedded in the interlayer corridor of LDH by an ion exchange process. The morphology, structure and composition of the composite coatings were investigated using scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry and Fourier transform infrared spectroscopy. Ball-and-disk friction wear experiments were carried out to measure the coefficient of friction, the amount of wear, and the morphology of the worn surface. The corrosion resistance of the coating is studied using dynamic potential polarisation (Tafel) and electrochemical impedance spectroscopy (EIS). The results showed that the LDH composite coating with unique layered nanostructure as a solid lubricating film can effectively improve the friction and wear reduction performance of the metal substrate. Chemical modification treatment by embedding vanadate anions in the LDH coating leads to the change of LDH layer spacing and the increase of interlayer channels, resulting in the best friction and wear reduction and corrosion resistance of the LDH coating. Finally, the mechanism of hydrotalcite coating as a solid lubricating film for friction and wear reduction is proposed.