铝锂合金混合酸阳极氧化及无铬封闭研究

Study on Mixed Acid Anodic Oxidation and Chromium Free Sealing of Aluminium Lithium Alloy

为有效提高铝锂合金的耐蚀性能,采用混合酸电解液(硫酸与柠檬酸的混合溶液)进行阳极氧化,然后对阳极氧化膜进行无铬封闭处理,并对阳极氧化膜的微观形貌、表面成分、厚度和耐蚀性能进行了分析表征。结果表明:混合酸阳极氧化后铝锂合金表面形成了均匀多孔的阳极氧化膜,主要含有Al、S和O元素,厚度为12.8μm,其耐蚀性能好于铝锂合金。沸水封闭、锆盐封闭、镍盐封闭和铈盐封闭对阳极氧化膜的厚度几乎没有影响,但封闭后阳极氧化膜表面平整度和致密性改善,耐蚀性能明显提高。铈盐封闭过程中同时生成水合氧化铝、铈氢氧化物和铈氧化物,更好的填充覆盖了孔洞,封闭效果好于沸水封闭、锆盐封闭和镍盐封闭,因此铈盐封闭阳极氧化膜表面更平整致密,抵御腐蚀能力增强,电荷转移电阻较铝锂合金提高了超过一个数量级,腐蚀失重仅为铝锂合金的1/9,可以显著提高铝锂合金的耐蚀性能。

Aluminium lithium alloy was anodized in mixed acid electrolyte(sulfuric acid and citric acid mixed solution)and then treated with chromium-free sealing in order to effectively improve its corro-sion resistance.The micromorphology and surface components of anodic oxide films were characterized and analyzed,and the thickness and corrosion resistance were also tested.The micromorphology,sur-face composition,thickness and corrosion resistance of anodic oxide film were analyzed and character-ized.The results show that a uniform porous anodic oxide film is formed on the surface of aluminium lithium alloy after anodized in mixed acid electrolyte,which mainly contains Al,S and O elements,and the thickness is 12.8μm.The corrosion resistance of anodic oxide film is better than that of alumini-um lithium alloy.Boiling water sealing,zirconium salt sealing,nickel salt sealing and cerium salt seal-ing have little effect on the thickness of anodic oxide film,but the surface flatness and compactness of the anodic oxide film after sealing were improved,and the corrosion resistance was improved obvious-ly.Hydrated alumina,cerium hydroxide and cerium oxide simultaneously generated during the process of cerium salt sealing,which could better fill and cover the holes,and the sealing effect was better than that of boiling water sealing,zirconium salt sealing and nickel salt sealing.Therefore,the surface of ce-rium salt sealed anodic oxide film is more smooth and compact and the corrosion resistance is enhanced.The charge transfer resistance is more than one order of magnitude higher than that of aluminium lithi-um alloy,and the corrosion weight loss is only 1/9 of that of aluminium lithium alloy,which can signif-icantly improve the corrosion resistance of aluminium lithium alloy.