Flow Effects on Corrosion of Galvanic Couples in Sea Water

Abstract

Abstract A unique “circling-foil” apparatus has been developed to study velocity effects on corrosion processes, and has been used initially to expose single metals and galvanic couples of some common marine structural materials in synthetic sea water electrolyte under controlled hydrodynamic conditions at relative velocities up to 3 m/s. The samples are deployed by mounting in a sample holder with a standard foil profile, which circles in a tank, with a turbulence trip wire at the leading edge of the foil. This scheme allows prediction and measurement of the fluid flow structure over the corrosion samples. Direct determinations of turbulence intensity and boundary layer thickness were made at various velocities, enabling correlations of hydrodynamic parameters with electrochemical data and other measures of corrosion behavior. The effects of velocity and potential distribution on average corrosion rates, and on the mode and distribution of corrosive attack and corrosion products, have been studied.