Abstract To improve the corrosion resistance, a superhydrophobic silica film on Mg–3.0Nd–0.2Zn–0.4Zr (wt.%, NZ30K) magnesium alloy was successfully prepared by the combination of micro-arc oxidation (MAO) and sol–gel method using tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) as precursors. The MAO layer with highly porous surface was formed as an intermediate layer to ensure the excellent adhesion of superhydrophobic silica film to the substrate. The parameters of the sol–gel process such as molar ratios of TEOS/C 2 H 5 OH and MTES/TEOS had significant effects on the surface morphologies and water-repellent properties of the silica films. A superhydrophobic silica film with static contact angle of 151° was obtained as the molar ratios of TEOS/C 2 H 5 OH and MTES/TEOS were 1/30 and 1/2 respectively. It is shown that the superhydrophobic silica film can significantly improve the corrosion resistance of NZ30K magnesium alloy by nearly three orders of magnitude by analysis of the potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests in 3.5 wt.% NaCl solution. 168 h immersion test further demonstrates that the superhydrophobic silica film can effectively provide long-term corrosion protection for NZ30K magnesium alloy. In addition, the superior corrosion protection performance of the superhydrophobic silica film compared with that of the pure silica film without the addition of MTES can be attributed to the good coverage of hydrophobic methyl groups on its surface, which could effectively decrease the direct contact surface to corrosive medium.

中文翻译：

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Mg-Nd-Zn-Zr镁合金超微弧氧化膜的微弧氧化与溶胶-凝胶法结合制备

摘要为提高耐蚀性，采用微弧氧化（MAO）和溶胶-凝胶法相结合，成功制备了Mg-3.0Nd-0.2Zn-0.4Zr（wt。％，NZ30K）镁合金上的超疏水二氧化硅膜。使用四乙氧基硅烷（TEOS）和甲基三乙氧基硅烷（MTES）作为前体。形成具有高度多孔表面的MAO层作为中间层，以确保超疏水性二氧化硅膜与基材的优异粘合性。溶胶-凝胶工艺的参数，例如TEOS / C 2 H 5 OH与MTES / TEOS的摩尔比，对二氧化硅膜的表面形貌和疏水性有重要影响。当TEOS / C 2 H 5 OH和MTES / TEOS的摩尔比分别为1/30和1/2时，获得了具有151°静态接触角的超疏水二氧化硅膜。通过在3.5重量％的NaCl溶液中的电动力极化和电化学阻抗谱（EIS）测试的分析表明，超疏水性二氧化硅膜可以将NZ30K镁合金的耐腐蚀性显着提高近三个数量级。168 h的浸没测试进一步表明，该超疏水二氧化硅膜可以有效地为NZ30K镁合金提供长期的腐蚀防护。此外，与不添加MTES的纯二氧化硅膜相比，超疏水性二氧化硅膜的优越的防腐蚀性能可以归因于疏水性甲基在其表面上的良好覆盖，这可以有效地减少与金属表面的直接接触表面。腐蚀性介质。