Chemical stability of porous anodic aluminum oxide in both acidic and alkaline solutions
Chemical stability of porous anodic aluminum oxide in both acidic and alkaline solutions
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DOI：
10.1016/j.tsf.2023.139784
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发表时间：
2023-03-12
期刊：
影响因子：
2.1
通讯作者：
Kikuchi, Tatsuya
中科院分区：
文献类型：
--
作者：
Iwai, Mana;Kikuchi, Tatsuya
在碱性四硼酸钠溶液中对铝进行阳极氧化，制备了在酸性和碱性溶液中均具有较高耐化学性的多孔阳极氧化铝（AAO）。在硫酸、草酸、磷酸、铬酸和依地膦酸五种主要酸性溶液和碱性四硼酸钠溶液中对5n Al板进行阳极氧化，形成aao。将氧化后的试样分别浸泡在pH = 1.3的0.52 M磷酸溶液和pH = 13.8的2.5 M氢氧化钠溶液中。随后，研究了浸泡前后aao的电化学阻抗测量和形态表征。在典型的酸性电解质（包括硫酸、草酸、磷酸和乙酸）中形成的aao完全溶解所需的时间随着阳极氧化电压的增加而线性增加。在铬酸中形成的AAO比这种线性关系表现出更高的耐化学性，因为形成的高纯氧化铝没有掺入阴离子。此外，在四硼酸钠溶液中形成的AAO在酸性和碱性溶液中都表现出最高的耐化学性，大约是在乙酸和铬酸中形成的AAO的两倍。这可归因于其较高的阳极氧化率和形成的高纯度氧化铝层。
A porous anodic aluminum oxide (AAO) possessing higher chemical resistance in both acidic and alkaline solutions was fabricated by anodizing Al in an alkaline sodium tetraborate solution. The 5 N Al plates were anodized in five types of major acidic solutions (sulfuric, oxalic, phosphoric, chromic, and etidronic acids) and in alkaline sodium tetraborate solution to form AAOs. The anodized specimens were then immersed in a 0.52 M phosphoric acid solution (pH = 1.3) and a 2.5 M sodium hydroxide solution (pH = 13.8). Subsequently, the electrochemical impedance measurements and morphological characterizations of the AAOs before and after immersion were investigated. The time required for the complete dissolution of the AAOs formed in typical acidic electrolytes, including sulfuric, oxalic, phosphoric, and etidronic acids, increased linearly with the anodizing voltage. The AAO formed in chromic acid exhibited a higher chemical resistance than this linear relationship owing to the formation of high-purity alumina without incorporated anions. Moreover, the AAO formed in sodium tetraborate exhibited the highest chemical resistance in both acidic and alkaline solutions - approximately two times higher than that formed in etidronic and chromic acids. This can be attributed to their higher anodizing ratio and the formation of a high-purity alumina layer.