添加剂对铝基复合材料微弧氧化膜组织及耐蚀性影响

Effect of additives on microstructure and corrosion resistance of micro-arc oxidation coatings of aluminum matrix composite

采用微弧氧化技术在铝基复合材料表面制备陶瓷膜。在Na Al O2溶液体系中,研究不同添加剂(Na H2PO2、Na OH)和不同正向脉冲电压(390、420和450 V)对陶瓷膜组织、结构和耐蚀性的影响。结果表明:陶瓷膜主要由γ-Al2O3组成,在添加Na OH电解液中陶瓷膜生长速率更快,所得陶瓷膜表面形貌更优异,结合更加紧密。在添加Na H2PO2的电解液中,所得陶瓷膜呈层片状,比较疏松,Si C颗粒氧化程度也很低。随着正向电压的升高,两种添加剂所得陶瓷膜的耐蚀性都是先升高后降低,且均在420 V时耐蚀性最好,添加Na OH电解液的陶瓷膜耐蚀性优于添加Na H2PO2电解液。

Ceramic coatings on aluminum matrix composite were prepared by microarc oxidation in sodium aluminate solution. The effects of additives( Na H2PO2 and Na OH) in the solution and anodic voltages on microstructure and corrosion resistance of the ceramic coatings were investigated. The results show that the ceramic coatings are composed of γ-Al2O3,and the growth rate of the coatings is faster as adding Na OH into the electrolyte as well as the better surface morphology of the coatings can be obtained. On the other hand,the coatings prepared in the electrolyte containing Na H2PO2 present loose and layered structure,and the oxidation degree of the Si C particles is low.With increasing the anodic voltages,both of the corrosion resistance of the coatings increases firstly,reaching the maximum values at 420 V,and then decreases. Moreover,the corrosion resistance of the coatings prepared in the electrolyte containg Na OH is better than that of the coatings prepared in the electrolyte with Na H2PO2 additive.