PARTLY‐WETTED GALVANIC CORROSION COUPLES

It is well known that the water‐line along a semi‐immersed sheet of metal enhances corrosion by providing easy access for atmospheric oxygen. Thirty years ago U. R. Evans coupled iron, submerged in water or brine, with partly‐emerging strips of several metals, and found that copper promoted the rusting more than nickel, and nickel more than lead. This type of corrosion is very frequent and deserves more quantitative consideration, since it is as yet little understood. Thus a recent study of the geometrical conditions leading to corrosion, as aided by a water‐line, revealed that what is commonly regarded as the effect of the meniscus also depends on a zone of dry metal above it. The present investigation re‐examines the role of the partly‐immersed metal in conjunction with the electrolyte surrounding it.