Kinetics of the electrolytic coloring process on anodized aluminum

Authors: Akolkar, Rohan; Wang, Yar-Ming; Kuo, Hong-Hsiang (Harry)

Source: Journal of Applied Electrochemistry, Volume 37, Number 2, February 2007 , pp. 291-296(6)

Publisher: Springer

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Abstract:

The kinetics of tin electrodeposition during the electrolytic coloring of porous anodic oxide films on aluminum is studied as a function of the oxide properties, e.g., the thickness of the porous oxide layer, and the surface resistance offered by the barrier oxide layer. While the thickness of the porous oxide layer is controlled by the anodization time, the surface resistance is controlled by the anodization voltage, and the anodization bath temperature. Steady-state polarization measurements are employed to characterize the dependence of the coloring kinetics on the oxide properties. Measurements indicate that the kinetics of the electrolytic coloring process can be accelerated by: (i) reducing the surface resistance of the oxide film (primarily offered by the barrier oxide layer) by growing the oxide at a lower anodization voltage, and/or a higher bath temperature, or (ii) growing a thinner porous oxide layer by decreasing the anodization time. The electrochemical measurements are supported by gravimetric analysis of electrolytically colored alumina samples (using calibrated wavelength-dispersive X-ray fluorescence spectroscopy), and by optical spectrophotometry.

Keywords: aluminum; anodization; electrolytic coloring; surface finishing; tin electrodeposition

Document Type: Research article

DOI: http://dx.doi.org/10.1007/s10800-006-9258-0

Affiliations: 1: Email: rohan.n.akolkar@intel.com

Publication date: 2007-02-01