ABSTRACT

The nucleation, propagation, and rehabilitation of pitting corrosion of Al–Mg–Si Aluminium alloy (AA6063) are studied in 3%NaCl solution by using electrochemical noise measurement. It shows that the composite film composed of sequent precipitation of ceria and 1-tetradecylphosphonic acid (DPA) presents the best pitting corrosion resistance compared with the independent ceria conversion film or self-assembling DPA film. XPS and microscopic Raman spectra confirmed that Ceria film is an excellent interlayer for the self-assembling of alkyl phosphate on the intermetallic particles in Al alloy. The anti-corrosion performance of Cerium oxides and DPA composite film is totally dependent on the deposition sequence. Prior deposition of ceria and then DPA film can increase the hydrophilicity of Al matrix and AlFeSi intermetallic particles, further promoting the self-assembling of upper DPA molecules, thus dramatically improving the overall and pitting corrosion resistance of AA6063. This could be attributed to the synergistic effects between the upper DPA film and underlying Ce conversion film. On the contrary, Prior assembly of DPA and then deposition of ceria, may significantly degrade their inhibition efficiency.

摘要

通过电化学噪声测量，研究了 Al-Mg-Si 铝合金（AA6063）在 3%NaCl 溶液中点蚀的形核、扩展和恢复。结果表明，与独立的氧化铈转化膜或自组装DPA膜相比，由二氧化铈和1-十四烷基膦酸（DPA）连续沉淀组成的复合膜具有最佳的耐点蚀性。XPS 和显微拉曼光谱证实，氧化铈膜是一种很好的中间层，用于在铝合金中的金属间化合物颗粒上自组装磷酸烷基酯。氧化铈和DPA复合膜的防腐性能完全取决于沉积顺序。先沉积二氧化铈，然后再沉积 DPA 薄膜可以增加 Al 基体和 AlFeSi 金属间化合物颗粒的亲水性，进一步促进上层DPA分子的自组装，从而显着提高AA6063的整体耐点蚀性和耐点蚀性。这可能归因于上层 DPA 膜和下层 Ce 转换膜之间的协同效应。相反，先组装 DPA，然后沉积氧化铈，可能会显着降低其抑制效率。