2519铝合金表面微弧氧化膜的结构与耐蚀性能

研究了2519铝合金微弧氧化膜表面形貌、截面形貌特征与成分分布特点、相结构以及微弧氧化膜的耐蚀性能.结果表明,氧化膜为55 μm厚膜时主要由α-A12O3、γ-A12O3和A16Si2O13组成,并有非晶相;截面形貌呈现明显的两层结构特征,致密层厚约35 μm,表面疏松层厚约20 μm.致密层中Al、Cu、O含量均高于表面疏松层的,而表面疏松层Si含量明显高于致密层的,A16Si2O13主要分布于表面疏松层.该氧化膜使铝合金试样的Icorr减小3个数量级以上,并明显提高了腐蚀电位.

Structure and Corrosion Performance of Ceramic Coatings on 2519 Aluminum Alloy by Micro-arc Oxidation

Protective ceramic coating is prepared on 2519 aluminum alloy by micro-arc oxidation （MAO）. Features of surface and cross sectional morphology, elements distribution, phase compositions and corrosion performance of MAO coating are investigated. The results show that the coating is composed of a-A1203, y-A1203 and Al6Si2013 with a little amorphous phase. Two layers with different microstructures respectively are observed. The outer layer is about 20 pm and shows many pores. The inner layer is dense with a thickness of about 35/~m. Concentrations orAl, Cu and 0 in the inner layer is higher than that in the outer layer, and reverse of Si, indicating mullite phase mainly distributes in the outer layer Compared with the blank, the corrosion current density is reduced by more than 3 orders and the corrosion potential shifts positively by the produced ceramic coating.