Chemical etching of a disordered solid: from experiments to field theory

TL;DR

This paper develops a two-dimensional theoretical model linking chemical corrosion of disordered solids to percolation theory, explaining experimental fractal corrosion patterns and the phenomenon of spontaneous corrosion arrest.

Contribution

It introduces a novel field theoretical approach and a self-organized gradient percolation model to describe corrosion processes in disordered solids.

Findings

Corrosion stops spontaneously at finite etchant concentration.

Corrosion surface exhibits fractal features near the percolation threshold.

Model aligns with experimental observations of corrosion patterns.

Abstract

We present a two-dimensional theoretical model for the slow chemical corrosion of a thin film of a disordered solid by suitable etching solutions. This model explain different experimental results showing that the corrosion stops spontaneously in a situation in which the concentration of the etchant is still finite while the corrosion surface develops clear fractal features. We show that these properties are strictly related to the percolation theory, and in particular to its behavior around the critical point. This task is accomplished both by a direct analysis in terms of a self-organized version of the Gradient Percolation model and by field theoretical arguments.