Formation and capacitance properties ofTi-Al composite oxide film on aluminum

来源期刊：中国有色金属学报(英文版)2010年第5期

论文作者：姚雷 刘建华 于美 李松梅 吴昊

文章页码：825 - 830

Key words：Al electrolytic capacitor; composite oxide film; anodized dielectric film; sol-gel coating; capacitance property

Abstract: Al specimens were covered with TiO₂ film by sol-gel dip-coating and then anodized in ammonium adipate solution. The structure, composition and capacitance properties of the anodic oxide film were investigated by transmission electron microscopy (TEM), Auger electron spectroscopy (AES), X-ray diffractometry (XRD) and electrochemical impedance spectroscopy (EIS). It was found that an anodic oxide film with a dual-layer structure formed between TiO₂ coating and Al substrate. The film consisted of an inner Al₂O₃ layer and an outer Ti-Al composite oxide layer. The thickness of layers varied with the number of times of sol-gel dip-coating. The capacitance of anodic oxide films formed on coated specimens was at most 80% higher than that without TiO₂. In film formation mechanism, it was claimed that the formation of composite oxide film was mainly affected by the structure of micro-pores network in TiO₂ coating which had an influence on Al³⁺ and O^2- ions transport during the anodizing.