Corrosion Performance Of Epoxy Resin Coatings Containing Silane Treated Nanoparticles On Mg-Li Alloy Surface

Mg-Li alloy has great potential for development in the fieds of aerospace, automotive,electronic communications and other industries due to its excellent properties. However, the poor corrosion resistance of Mg-Li alloy limits their wide applications. The epoxy coating can greatly improve the corrosion resistance of metals and their alloys, but the epoxy coating can be impregnated by aggressive species such as oxygen, water and chlorine ions. The protective properties of epoxy coatings can be improved by adding fillers. Nanoparticles are a good kind of filler, and it can enhance protective performance of epoxy coatings. Silanes has special molecular structure so that silanes can react with organics and inorganics forming chemical bonds at the same time and can improve protective performance of epoxy coatings. In order to enhance protective performance of epoxy coatings, the nanoparticles treated with silanes was added into epoxy coatings.In this paper, epoxy organic coatings containing Titanium dioxide modified by bis-(y-triethoxysilylpropyl)-tetrasulfide (KH-69) or vinyltriethoxysilane (KH-151) and containing Zirconium dioxide modified by KH-69 or KH-151 silane were prepared on the Mg-Li alloy surface, respectively. And the anti-corrosion performance of the four kinds of epoxy oranic coatings with different contents of nanoparticles in 3.5% NaCl were studied by electrochemical impedance spectroscopy (EIS). Besides, the structure and morphology of silane modified nanoparticles, thickness and morphology of epoxy coatings were studied by FT-IR, UV,TEM and SEM. Meanwhile,the dispersity of nano TiO2 and nano ZrO2 in the epoxy resin coatings was also studied.The FT-IR results show that nano TiO2 or nano ZrO2 interacts with two kinds of silanes,which leads to form chemical bonds of Si-O-Ti or Si-O-Zr. The dispersion stability of nanoparticles (treated and untreated with silanes) was evaluated in xylene by means of sedimentation test. The results prove that the nanoparticles treated with silanes can scatter in the organic solvent uniformly.Epoxy resin coatings containing nano TiO2 modified by KH-69 or KH-151 were prepared on the surface of Mg-Li alloys by coating method. The effect of additive amount of treated nano TiO2 on the epoxy coatings was evaluated. The SEM results show that the thickness of coatings are 50±5 ?m and the coatings are uniform and compact. The different samples were evaluated by EIS in 3.5% NaCl. The EIS results reveal that the coating with 0.5% TiO2 nanoparticles modified by KH-69 silane possesses the best corrosion performance among the coating specimens. The corrosion resistance of the coatings containing TiO2 nanoparticles modified by KH-69 silane was improved considerably. The coating with 0.5%TiO2 nanoparticles modified by KH-151 silane exhibits good corrosion performance among the coating specimens.Epoxy resin coatings modified by nano ZrO2 treated with KH-69 and KH-151 were coated on the surface of Mg-Li alloys. The effect of additive amount of silane modified nano ZrO2 on the epoxy coatings was evaluated. The SEM results show that the thickness of coatings are 50±5 ?m and the coatings are uniform and compact. The different samples were evaluated by EIS in 3.5% NaCl. The EIS results reveal that the coating with 1.0% ZrO2 nanoparticles modified by KH-69 possesses the best corrosion performance among the coating specimens. The corrosion resistance of the coatings containing ZrO2 nanoparticles modified by KH-69 silane was improved considerably. The coating with 1.0% ZrO2 nanoparticles modified by KH-151 exhibits good corrosion performance among the coating specimens.