Unveiling the influence of gravity on pitting corrosion through advanced high-throughput corrosion test method

Abstract

Bipolar electrochemistry is a high-throughput corrosion testing method capable of applying a quasi-linear potential gradient across test specimens. This study employs—bipolar electrochemistry corrosion testing to investigate the influence of gravity on pitting corrosion of type 304L and 420 stainless steel across a broad range of applied potentials. Gravity modifies the distribution of current density on the bipolar electrode without altering the potential distribution. The impact of gravity on pitting corrosion is achieved through its effects on the dilution of the electrolyte and the removal of the salt film within the pits. Pits oriented in a face up position demonstrate smoother morphologies, larger cross-sectional areas and pit volumes. In contrast, pits oriented in perpendicular and facedown positions exhibit pit shape. Under conditions governed by diffusion and activation control, pits can up to over 100 μm. Additionally, crystallographic pits are observed to form in areas subjected to high applied potentials.

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