Fabrication of the Ordered Nanocells of Anodic Aluminum Oxide and the Generation of Zn-Mn Ferrite Phase within Them

Different ceramic coatings can be fabricated on aluminum alloys by the anodizing process. In this process, the nanocells can grow directly from the bottom toward the surface of the coating layer. The ordered porous structure of the anodic aluminum oxide (AAO) layer is a very suitable template for the growth of magnetic nanowires. At this study, one- and two-step anodizing processes were conducted to fabricate the oxide layer in an appropriate acidic electrolyte at three different temperatures (۰, -۵, -۱۰ ⁰C) and three different voltages (۲۰, ۲۷, ۳۵ V) for ۵۰ min on a ۷۰۷۵ aluminium alloy (۷۰۷۵ AA). The results showed that the samples’ thickness increased with increasing the voltage and decreasing the temperature. The microhardness of samples under different voltages increased with decreasing the temperature. Field emission scanning electron microscopy (FESEM) images were taken from the back and cross-sections of nanocells. The results indicated that the samples which were anodized by the two-step process at -۱۰ ⁰C and ۳۵ V had yielded the best order. Afterward, Zn-Mn ferrite nanowires were produced by electrochemical deposition within the nanocells. X-ray diffraction (XRD) confirmed the formation of the Zn-Mn phase, and FESEM images showed the bulk morphology of nanowires with an appropriate saturation magnetization of about ۶۳.۶۴ emu/g.

Keywords:

anodizing , temperature , nanocells , ferrite , magnetic