摘要
多孔型阳极氧化铝(PAA)和多孔阳极氧化钛纳米管因其在诸多领域的广泛应用而备受关注.然而这类多孔阳极氧化物中纳米孔道的形成机理至今还不清楚,阳极氧化过程中电流-时间曲线与多孔形貌之间的关系至今无法解释.本文从致密型阳极氧化铝(CAA)的击穿机理入手,详细对比了CAA和PAA形成过程的区别与内在联系,从两种氧化膜电流-时间曲线(或电压-时间曲线)的分界点这个全新视角入手,找出了阳极氧化过程中氧化物形成效率下降的本质原因是电子电流的产生和氧气的析出.在CAA中球形孔洞的证据充分说明初期的规则孔洞是氧气气泡形成的.铝在混合电解液中阳极氧化的结果表明,一旦氧气析出停止,孔道生长就停止并被致密型的氧化物覆盖,一种新型的复合型氧化膜由此而得.最终结果表明:在PAA的形成过程中,适当的电子电流是氧气析出和孔洞形成的保证,适当的离子电流是氧化物形成和孔壁生长的保证.
Porous anodic alumina （PAA） and porous anodic TiO2 nanotubes have received considerable attention because of their appli- cations in a number of fields. The formation mechanisms of nanopores and nanotubes in these porous anodic oxides, however, have remained unclear until now. The interactions between porous structural features and current-time transients in anodizing process cannot be successfully explained. Based on the mechanism of dielectric breakdown of the compact anodic alumina （CAA）, the differences and internal relations in their forming processes between CAA and PAA are contrasted in detail. From this innovative standpoint, according to the divergence Of PAA and CAA in their current-time curves （or voltage-time curves）, two essential causes which induce the decrease of the forming efficiency of oxide in the anodizing process, that is, the generation of the electronic current and the oxygen evolution, are presented in the paper. The evidences of the round hollows within the CAA films, show that the regularly embryo pores result from the oxygen bubbles. According to the aluminum anodizing in the mixed-electrolyte, the results show that once oxygen evolution stopping, the pore growth must be stopped, and the pores must be sealed by the above compact oxide. A novel composite film of the anodic oxide is presented. All of the above conclusively show that in the forming process of PAA, an appropriate magnitude of electronic current ensures the oxygen evolution and the pores formation, an appropriate magnitude of ionic current ensures the oxide formation and growth of pore wails.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2012年第22期498-510,共13页
Acta Physica Sinica
基金
国家自然科学基金(批准号:61171043
51077072)
国家科技重大专项资金(批准号:2009ZX01021-002)资助的课题~~
关键词
阳极氧化
多孔型阳极氧化铝
电子电流
纳米多孔材料
anodization, porous anodic alumina （PAA）, electronic current, nanoporous materials
