几种Al合金阳极氧化膜的孔蚀行为

用电化学极化和SEM分析等方法研究了工业纯铝L2，硬铝LY12和超硬铝LC4 3种Al合金的阳极氧化膜在NaCl溶液中的孔蚀行为.3种合金氧化膜在1 mol/L的中性、酸性、碱性NaCl溶液中均发生孔蚀，其阳极极化电流呈台阶式上升.当阳极氧化膜厚度增大时，L2的氧化膜耐孔蚀性能提高，LY12和LC4的氧化膜耐蚀性则没有明显改善.L2的阳极氧化膜上小孔贯穿氧化膜后，优先在Al基体中发展，形成外形规则、内部深 而大的小孔；LY12和LC4的阳极氧化膜上小孔则有膜中发展倾向，形成大而浅的小孔.氧化膜中的合金元素对腐蚀行为有重要影响.

PITTING CORROSION BEHAVIOR OF ANODIZATION FILM OF THREE ALUMINUM ALLOYS

Pitting corrosion behavior of anodic film on three aluminum alloys,L2,LY12 and LC4,in NaCl solutions were studied using methods of potentiodynamic polarization and SEM.Pitting corrosion occurred for all the three anodic films in nuetral,acidic and basic solutions of 1 mol/L NaCl.The polarization currents showed stepwise increases.Pitting corrosion resistance of the anodic film for L2 alloy increased with increase of the film thickness,but film thickness had little influence on corrosion resistance of the films on LY12 and LC4 alloys.For L2 alloy,once a pit penetrated the film,it developed preferentially under the film inwords,resulting in deep pit with small mouth.For LY12 and LC4 alloys,the pits intended to grow laterally in the film,and thus big and sallow pits were formed.Different alloying elements in the alloys were responsible for the differences in corrosion behaviors of the anodic films.