Preparation of silane-modified silicate-based composite coatings on magnesium alloys for enhancing wear and corrosion resistant performance

To enhance wear and corrosion resistance of magnesium alloy, slurry method was used to prepare a ceramic coating with sodium silicate modified by gamma-(2,3-epoxypropoxy) propytrimethoxysilane (GPTMS). The influence of GPTMS content on the structure, morphology and properties of the coating was studied, together with the curing mechanism. Results showed that GPTMS can promote the curing of coating, form stable [-Si-O-Si-] mesh structure and reduce the generation of defects during condensation. Electrochemical analysis and wear tests indicate that the corrosion current density of the coating was reduced by two orders of magnitude after adding 10 wt% GPTMS, while the corrosion potential of the coating significantly shifted to the positive direction. At the same time, wear rate of the modified coating was also reduced obviously. Our work indicates that the corrosion and wear resistance of the coating can be effectively improved after modification with GPTMS.