新型高强稀土Al-Zn-Mg-Cu-Sc铝合金的阳极氧化及其抗腐蚀性能研究

针对添加稀土Sc的新型高强7000系铝合金中析出相的特征,发展了相应的阳极氧化工艺,并通过封孔后处理进一步提高膜层的致密性。结果表明,在7000系稀土铝合金表面存在的含Sc析出相作为微阴极,加速其周围Al基体的溶解,影响成膜均匀性。通过调整氧化溶液组成及电参数,在铝合金表面获得了均匀的阳极氧化膜。同时对比了氟锆酸盐、铈盐及沸水3种封孔工艺对阳极氧化膜耐蚀性的影响,结果显示沸水封孔后的阳极氧化膜呈银白色,膜层均匀致密,无缺陷和微裂纹存在,耐蚀性最佳,该膜层盐雾测试336 h未发生腐蚀,可以满足实际工业应用的要求。

Investigation of Anodic Film on a Novel RE-containing Al-Alloy Al-Zn-Mg-Cu-Sc

A novel anodic process was developed for a RE-containing 7000 series Al-alloy Al-Zn-Mg-Cu-Sc.Further,sealing-pore post treatments were carried out to improve the compactness of the anodic film.The results indicate that the precipitated Sc-containing phases on the surface of 7000 series Al-alloy act as micocathodes to accelerate the corrosion of Al matrix,which has a negative effect on the uniformity of the anodic film.In order to solve this trouble,the formula and electric parameters of the electrolyte bath were adjusted,hence,a uniform and smooth anodic film is formed on the surface of the Al-alloy.Meantime,three sealing-pore processes with fluozirconate,cerate and boiling water respectively were carried out to improve the compactness of the anodic film.It is found that after boiling water sealing-pore,the anodic film exhibits a sliver like uniform surface without defects and microcracks,among others,that film presents the best corrosion resistance,and the film can keep intact after salt spray test for 336 h,which can satisfy the requirement for the actual applications.