Stabilisation of marine iron artefacts

Abstract

Chloride ions stimulate the corrosion of iron in sea water and enable attack to continue even when artefacts are removed from the sea, dried, and either stored or displayed. This paper reviews the corrosion processes which occur and methods employed to remove chloride ions from the corrosion products on iron artefacts. A method is described to mass produce identical porous iron samples. After exposure to aerated sea water the chloride concentration is determined and a quantitative assessment made of the efficiency of chloride ion removal by different techniques. Electrolysis has been shown to be effective. The chloride removal is diffusion controlled and the superimposition of ultrasound accelerates the process. A reduction of 95% chloride has been achieved using electrolysis with ultrasound which is thought adequate to prevent further corrosion during storage and display.