Mg-Nd-Zn-Zr镁合金表面超疏水SiO2薄膜的制备及其表征

以微弧氧化层(MAO)为预处理过渡层,正硅酸乙酯(TEOS)和甲基三乙氧基硅烷(MTES)为主要原料,采用sol-gel和浸渍-提拉相结合的方法在Mg-Nd-Zn-Zr(NZ30K)镁合金表面获得甲基(-CH3)疏水基团表面修饰的超疏水SiO2薄膜,实现了NZ30K镁合金表面的超疏水改性.同时研究了微弧氧化层的表面特征、sol-gel过程中TEOS/乙醇摩尔比(TEOS/EtOH)和MTES添加量(MTES/TEOS摩尔比)对所制备超疏水SiO2薄膜表面形貌和润湿特性的影响.结果表明:NZ30K镁合金经过微弧氧化处理后,表面呈现的微米-纳米尺度上多孔的粗糙结构,其表面体现为亲水性,但有利于提高超疏水SiO2薄膜与NZ30K基材的结合力;当TEOS/EtOH摩尔比为1/30,MTES/TEOS摩尔比为1/2时,SiO2薄膜表面的静态接触角达到151°,其表面具有超疏水特性;而进一步提高MTES/TEOS摩尔比至1时,其静态接触角有所提高,达到153°.红外光谱(FT-IR)表明NZ30K镁合金表面SiO2薄膜的超疏水特性是由于MTES的引入使得-CH3疏水官能团能够成功地嫁接到SiO2粒子的表面.

Preparation and Characterization of Superhydrophobic Silica Film on Mg-Nd-Zn-Zr Magnesium Alloy via Sol-Gel Process

A superhydrophobic silica film on Mg-Nd-Zn-Zr magnesium alloy pretreated by micro-arc oxidation(MAO) was achieved following the sol-gel route using tetraethoxysilane(TEOS) and methyltriethoxysilane(MTES) as precursors and the dip-coating technique.The effects of the surface characteristics of MAO coating,the molar concentration of TEOS(TEOS/EtOH) and molar ratio of MTES/TEOS on the surface morphology and hydrophobicity of the obtained silica film were investigated.The results showed that pretreated MAO coating on Mg-Nd-Zn-Zr magnesium alloy became hydrophilic owing to its micro and nano-scale porous structures,however,which could improve the adhesion between the superhydrophobic silica film and NZ30K substrate.When the molar ratio of TEOS/EtOH=1/30 and MTES/TEOS=1/2,the silica film became superhydrophobic with static contact angle(CA) of 151°.Further increasing the molar ratio of MTES/TEOS to 1,the CA of obtained silica film reached 153° and was higher than that with molar ratio of MTES/TEOS=1/2,attributing to the introduction of more methyl groups(-CH3) on the surface of SiO2 particles proved by the results of FT-IR.