Fractal characterization of two-dimensional aluminum corrosion fronts

Abstract

The corrosion of aluminum foils in a two-dimensional cell has been investigated experimentally. The corrosion was allowed to attack from only one side of an otherwise encapsulated metal foil. A 1M NaCl (pH=12) electrolyte was used and the experiments were controlled potentiostatically. Experiments were performed at two different potentials. Photographs from the experiments were digitized and the interfaces between the electrolyte and metal (the corrosion fronts) were identified. The corrosion fronts were analyzed using four different methods, which showed that the fronts can be described in terms of self-affine fractal geometry over a significant range of length scales. The width as a function of length showed self-affine scaling with a Hurst exponent of 0.65±0.05 for both fronts. Results from corrosion experiments using zinc and copper are briefly mentioned.