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摘要
The electrochemical method for obtaining the oxide coatings of the Al-Al2O3-M composite structure is based on a two-stage process:
anodic oxidation of aluminium with the formation of a porous oxide coating
cathodic deposition of 'foreign' metal ions (e.g. Ni, Co, Fe, Cu, Ag, etc.) from an aqueous solution with the direct, pulsating, reversing, or alternating current.
In the present study, the oxide layers on aluminium with an ordered pore structure were obtained in a two-stage process of anodic oxidation in an oxalic acid solution. In the Al2O3 layers that are obtained, the cell parameters were changed by pore widening and barrier layer thickness reduction. These processes resulted in obtaining thin membranes, in which cells in the aluminium oxide layer had the following dimensions: pore diameter of similar to 80 nm, single pore wall thickness of similar to 25 nm, and a height of similar to 5 mu m. Those membranes were used as a 'templates' for the incorporation of cobalt and iron particles.
The metals were deposited in to membrane pores by the electrodeposition of cobalt and iron from sulphate electrolytes. Measurements were carried out using direct and reversing current (PRC).
The microscopic observations of cobalt and iron nanowires indicate that the membrane pores were not entirely filled by deposited metals. Although in practice, each pore was 'built-up' by a metal, but the length of the nanowires ranged from 1 (Co) to 2 mu m (Fe), while the pore height in the membrane was approx. 5 mu m.
The cathode efficiencies of the studied metals electrodeposition were determined by using direct current. These efficiencies were not high due to hydrogen co-evolution.
- 出版日期2009
