电流密度对海水淡化用铝合金微弧氧化陶瓷膜层耐蚀性的影响

在硅酸盐体系中研究了双极性脉冲电源的电流密度对6061铝合金微弧氧化的影响。结果表明,电流密度对膜层的生长、形貌及耐蚀性具有明显的影响;电流密度为15.0 A/dm2时,起弧时间最短为86 s,且膜层形貌均匀、致密,腐蚀电位E0和腐蚀电流密度Icorr分别达到-0.526 72 V和5.287×10-8A/cm2,表现出良好的耐蚀性能。用高浓度海水喷淋腐蚀试验表明来自海水中的Cl-阴离子只能进入MAO膜层的疏松表层,生成可溶性的Al-O-Cl络合物,造成表面出现大量"海绵絮状"孔洞,但Cl-、SO24-等阴离子无法进到膜层内部致密层,从而基体不被腐蚀。

Effect of current density on corrosion resistance of micro-arc-oxidation ceramic coatings formed on aluminum alloys used for seawater desalination

Effects of current density of a bipolar square pulse power source on the 6061aluminum alloys’ MAO were studied in silicate electrolyte.The results show that the current density has an important influence on the mechanism,topography as well as corrosion resistance of the micro-arc oxidation coatings.When current density is 15.0 A/dm2,minimum arcing time is 86 s and a dense and uniform ceramic coating can be obtained,and the corresponding corrosion potential E0 and corrosion current density Icorrrespectively equal to-0.526 72 V and 5.287×10-8 A/cm2.The coating exhibits very well corrosion resistance.It also shows that the Cl-from seawater can only enter into the loose layer of the MAO ceramic coatings in the high concentrations of sea water spray corrosion tests,and caused large numbers of "sponge flocculent" voids emerging on the ceramic coatings surface by a lot of resolved Al-O-Cl complex,but the Cl-,SO2-4 ions can’t enter into the dense layer to protect the matrix from corrosion.