材料期刊网

用透射电镜、标记原子及等离子体发射光谱定量分析等技术,研究了铝阳极氧化膜生长过程中离子迁移分数及其对膜形态的影响。实验发现,在膜形成过程中,铝和含氧离子沿相反方向漂移穿过膜。在同一电解质溶液中,铝离子的真实迁移分数基本恒定。当电流密度超过某一临界值时,部份铝离子在膜与溶液界面处形成新膜物质,膜的形态为壁垒型。而当电流密度小于临界电流密度时,全部铝离子均进入溶液。这时膜完全由含氧离子在膜与基体界面处形成,由于溶液对膜外表面的侵蚀,形成的膜为多孔型。推导了膜生长效率的理论表达式;表观迁移分数的关系式.用溶解—沉积理论解释了铝离子在膜与溶液界面处形成新膜物质的机理。

The variation role of ion transport number during the growth of anodic films on aluminium and its effect on film morphology have been studied by using TEM allied with ultramicrotomy sectioning,marker technique and quantitative chemical analyses by ICP-AES.The results show that athe alumin- ium and oxygen-containing ions migrate in opposite directions through the film.In a particular electrolyte,the real transport number of aluminium ions is a constant.When the applied anodic current density exceeds a critical value,a fraction of the aluminium ions acts as film material at the film- electrolyte interface in the form of barrier film.On the other hand,when the applied anodic current density is less than the critical value,all the outwardly migrating aluminium ions enter into the electrolyte and hence the film is entirely formed by oxygen-containing inos at the film-metal interface. The film formed under this condition is porous due to attack of the electrolyte on the outer film surface.Mathematic expressions of film growth efficiency and the relationship between apparent and real transport numbers have been derived.The process of film material formation by aluminium ions at the film-electrolyte interface is explained by a direct dissolution-precipitation theory.