Topographical and statistical studies of the corrosion damage underneath a sulfide film formed on a Cu surface

Abstract

Damage to Cu corroded in sulfide-containing solutions was investigated using scanning electron microscopy and surface profilometry. For dilute sulfide solutions (≤ 5 × 10⁻⁵ M), a thin, porous film was formed, and general corrosion to a depth of < 1 μm observed. At a higher concentration (5 × 10⁻⁴ M), a compact film was formed and micro-galvanic corrosion observed. With increasing exposure time at higher concentration, the extent of micro-galvanic corrosion decreased in favor of general corrosion, as the aspect ratio of the locally corroded sites increased. This indicates that micro-galvanic corrosion will eventually be stifled and only rough general corrosion observed.