A trace amount of MXene@PDA nanosheets for low-temperature zinc phosphating coatings with superb corrosion resistance

Abstract

In this study, MXene nanosheets were functionalized by polydopamine to fabricate MXene@PDA (PMX) hybrid nanomaterial as an accelerator for low-temperature phosphating. PMX structure had a large specific surface area and the dispersibility of PMX in the phosphating bath was higher than that of MXene. The phosphate coating obtained by introducing 0.025 g/L PMX (0.025-PMX coating) into the phosphating bath showed excellent comprehensive properties compared to past reports of nanomaterials used as accelerators since 2010. The phosphate coating was 81.52% heavier in mass per unit area and 98.93% lower in porosity than the pure phosphate coating. Furthermore, electrochemical impedance spectroscopy (EIS) data showed that the |Z0.01 Hz| of 0.025-PMX coating was approximately two orders of magnitude higher than that of the pure coating. Subsequently, we proposed a mechanism for the positive impact of trace amounts of PMX nanosheets on phosphate coatings. This study demonstrates the importance of further studying nanomaterials as phosphating accelerators.