Zn-Al-[V_(10)O_(28)]^(6-)双层氢氧化物掺杂对LY12铝合金表面溶胶-凝胶涂层性能的影响

Effect of Doping with Zn-Al-[V_(10)O_(28)]^(6-) Layered Double Hydroxide on the Properties of Hybrid Sol-Gel Coatings on the LY12 Aluminum Surface

采用共沉淀法制备Zn-Al-[V10O28]6-双层氢氧化物(以下简称LDH-V),研究不同添加浓度(0.0、0.25×10-3、0.75×10-3、1.5×10-3、3.0×10-3mol·L-1)的LDH-V对LY12铝合金溶胶-凝胶涂层形貌、耐蚀性的影响.采用扫描电子显微镜(SEM)和傅里叶变换红外(FTIR)光谱研究LDH-V对涂层形貌和结构的影响.运用中性盐雾实验对涂层进行耐蚀性评估.利用电化学方法对涂层在0.05 mol·L-1的NaCl溶液中的腐蚀行为进行研究.探讨加入LDH-V后溶胶-凝胶涂层的耐蚀机理.结果表明,一定量LDH-V的加入不仅可以提高溶胶-凝胶涂层的耐蚀性能,还可对涂层被破坏区域进行自修复,起到延缓铝合金基体腐蚀的作用.然而,当LDH-V的添加溶度超过一定值时,会破坏涂层的完整性并降低涂层的腐蚀防护性能.实验结果表明LDH-V最佳的添加浓度为1.5×10-3mol·L-1.

Zn-Al-[V10O28]6- layered double hydroxide （LDH-V） as a type of corrosion inhibitor was prepared with the co-precipitation method using one solution containing zinc and aluminum nitrates precursors and a second solution containing Na3VO4, where the decavanadate anion is speciated at pH 4.5. The hybrid sol- gel solution was prepared from 3-glycydoxypropyltrimethoxysilane （GPTMS） as the organic precursor sol and zirconium n-propoxide （TPOZ） as the inorganic precursor sol. The doped coatings were obtained by dip coating the way that the samples were immersed into solutions with different LDH-V concentrations （0.0, 0.25×10-3, 0.75× 10-3, 1.5×10-3, 3.0× 10-3 mol. L-1）. The morphology and corrosion resistance of the solgel coating doped with different LDH-V concentrations were studied. The sol-gel coatings were investigated by scanning electron microscopy （SEM） and Fourier transform infrared （FTIR） spectroscopy. The salt spray test was used to evaluate the corrosion resistance of the different coatings. The corrosion behavior of the coatings was evaluated by electrochemical impedance spectroscopy （EIS） during immersion in 0.05 mol L-1 NaCI solution. The results showed that LDH-V not only improves the corrosion resistance of the coating, but also provides a function for self-healing of broken coatings. However, when the LDH-V doping concentration was high, it destroyed the integrity of the coatings and decreased the corrosion resistance of the coatings. The best LDH-V doping concentration was 1.5× 10-4 mol·L-1.