دانلود مقاله A Comparison between Self-ordering of Nanoporous Aluminum Oxide Achieved by Two and Three Step Anodic Oxidation
سال انتشار: ۱۳۸۶
محل انتشار: دهمین کنگره ملی خوردگی ایران
تعداد صفحات: ۷
M. J. Aimasi –
M Abdollahzadeh –
F Nasirpouri – Department ofMaterials Engineering, Sahand University ofTeclmology, Tabriz, Iran
Template-base synthesis is known as a successful approaching method to a wide variety of nanostructures. Among frequently used templates, anodic aluminum oxide (AAO) has attracted considerable attention because of its natural self-ordering, obtained during twostep anodic oxidation process. High purity aluminum foils were anodized in an electrolyte of0.3 M oxalic acid under potentiostatic 40 V for two and three steps, right afterannealing, substrate surface chemical treatment and electropolishing. Current-time curves recorded for each step during a two- and three step anodizing, and scanning electron microscopy (SEM) were used to examine the degree of ordering achieved for nanopores. The current-time curves elucidate that as soon as current flows through the cell, a drastic drophappens until it increases up to a constant value which indicates growth ofoxide layer on the substrate, and the variation ofcurrent versus time is almost equal for all three steps. Scanning electron micrographs show hexagonally arranged 45 nm pores in a mannerwhich contribute into the formation of highly ordered areas, called domains. Domains are placed beside each other like a polycrystalline structure after two- and three-step anodizing, while larger ones are clearly observed over the surface after three-step anodizing.