建筑铝材在不同电解液体系中阳极氧化及氧化膜性能比较

Anodic oxidation of construction aluminum in different electrolyte systems and performance comparison of oxide films

为进一步提高建筑行业常用6063铝合金的耐腐蚀性能,从而延长建筑构件的使用寿命,分别在纯硫酸电解液、硫酸与硼酸混合电解液、硫酸与柠檬酸混合电解液、硫酸与甘油混合电解液以及硫酸与硼酸、柠檬酸和甘油混合电解液体系中对6063铝合金进行阳极氧化,并比较不同氧化膜的形貌特征、厚度、物相结构和耐腐蚀性能。结果表明:不同氧化膜都具有多孔密布的形貌特征,厚度相近并且由ɑ-Al_(2)O_(3)相和γ-Al_(2)O_(3)相组成,但孔隙率和表面致密性明显不同,导致耐腐蚀性能存在差异。在混合酸电解液体系中制备的氧化膜孔隙率最低,仅为12.1%,表面致密性最好并且具有最正的腐蚀电位−0.511 V、最低的腐蚀电流密度1.15×10^(-6)A/cm^(2)和最高的极化电阻22.05 kΩ·cm^(2),经过96 h盐雾实验后其腐蚀程度较轻。添加适量硼酸、柠檬酸和甘油具有协同缓蚀效果,因此混合酸电解液体系对氧化膜的溶解能力弱,能明显改善氧化膜表面致密性进一步提高其耐腐蚀性能,作为表面改性层可以更好地保护铝合金基体,延缓腐蚀。

The 6063 aluminum alloy commonly used in the construction industry was anodized in pure sulfuric acid electrolyte,sulfuric acid and boric acid mixed electrolyte,sulfuric acid and citric acid mixed electrolyte,sulfuric acid and glycerol mixed electrolyte,and sulfuric acid,boric acid,citric acid and glycerol mixed electrolyte in order to further improve the corrosion resistance of 6063 aluminum alloy and then extend the service life of construction components.And the morphology characteristics,thickness,phase structure and corrosion resistance of the different oxide films were compared.The results showed that the different oxide films had the morphology characteristics of dense porosity with similar thickness and consisted of ɑ-Al_(2)O_(3) and γ-Al_(2)O_(3) phase.However,the porosity and surface compactness of the different oxide films were obviously different,resulting in different corrosion resistance.The oxide film prepared in mixed acid electrolyte system had the lowest porosity of 12.1%,the best surface compactness,the most positive corrosion potential of -0.511 V,the lowest corrosion current density of 1.15×10^(-6) A/cm^(2) and the highest polarization resistance of 22.05 kΩ·cm^(2).After 96 h salt spray experiment,the corrosion degree of the oxide film was lighter.Adding appropriate amount of boric acid,citric acid and glycerol had a synergistic corrosion inhibition effect,so the mixed acid electrolyte system had a weak ability to dissolve the oxide film,and can significantly improve the surface compactness of the oxide film to further improve its corrosion resistance.As a surface modification layer,the oxide film prepared in mixed acid electrolyte system can better protect aluminum alloy matrix and delay corrosion.