Ti3C2Tx-based composite coating on AZ31B Mg alloy surface for improved anti-corrosion/wear-reducing properties

The poor wear resistance and corrosion resistance of AZ31B magnesium alloy are the main factors limiting its application. Herein, a simple spin-coating method was used to prepare MXene/polyvinyl alcohol (Ti3C2Tx/PVA) composite coating on the magnesium alloy surface. The results of corrosion resistance tests of the composite coating in a solution of 3.5% sodium chloride showed that the corrosion rate of the composite coating was about five orders of magnitude less than that of the substrate of the magnesium alloy. On the one hand, the layered structure of Ti3C2Tx could extend the corrosive media's diffusion path. On the other hand, PVA entering into the non-oxidized area of Ti3C2Tx could reduce the inherent defects of Ti3C2Tx and help to form a complete and continuous layer, resulting in a good barrier effect and improving the corrosion resistance of the substrate. In addition, the Ti3C2Tx/PVA coating has the best tribological properties with the lowest coefficient of friction (COF) and wear rate, with a wear rate approximately two orders of magnitude lower than that of the magnesium alloy substrate, approximately 4 × 10−5·mm3·N−1·m−1. Due to the excellent wear resistance of the layered Ti3C2Tx and the addition of PVA, the coating exhibits good bonding strength and presents an ordered brickwork structure through the hydrogen bonding network. Therefore, the suitable surface coating design combing Ti3C2Tx with PVA could endow the AZ31B Mg alloys with excellent corrosion/wear resistance.