硝酸铈封闭对2A12铝合金己二酸-硫酸阳极氧化膜耐蚀性的影响

Effects of Cerous Nitrate Sealing on Corrosion Resistance of Adipic-sulfuric Acid Anodic Oxide Films on 2A12Aluminum Alloy

研究了硝酸铈溶液封闭对2A12铝合金己二酸-硫酸阳极氧化膜耐蚀性的影响,通过盐雾腐蚀实验、电化学动电位极化扫描法和电化学阻抗谱法(EIS)对阳极氧化膜的耐蚀性进行研究,采用场发射扫描电镜(FE-SEM)观察试样封闭前后的表面微观形貌,并与稀铬酸封闭、沸水封闭传统工艺进行比较。结果表明:采用硝酸铈溶液封闭的2A12铝合金阳极氧化膜腐蚀电流减小,阻抗值增大,耐腐蚀性增强。阳极氧化膜表面呈致密的花瓣状,多孔层内及氧化膜表面附着一层致密铈的氧化物或氢氧化物,其耐蚀性优于沸水封闭,与稀铬酸封闭相当。

Effects of cerous nitrate sealing on corrosion resistance of adipic-sulfuric acid anodic oxide films on 2A12 aluminum alloy were investigated. The corrosion resistance of anode oxide films was studied by using salt spray tests, potentiodynamic polarization and electrochemical impedance spec troscopy （EIS）. The surface microtopography of anodic oxide films was observed by using the field emission scanning electron microscope （FE-SEM） and was compared with diluted chromic acid sealing and boiling water sealing. The results show that after sealing in the cerous nitrate solution, corrosion current of the anodic oxide films decreases, the impedance increases and the corrosion resistance is en hanced significantly. The surface morphologies of anodic oxide films are petaloid like with some ceri- um oxide or cerium hydroxide adhering to surface of the anodic oxide films and porous layer. The corrosion resistance of films with cerous nitrate sealing is better than that of films with boiling water sealing and are corresponded with diluted chromic acid sealing.