A laboratory study was made to determine the effect in water of single or mixed impurities on the corrosion of aluminum or steel. This study utilized the conductance technique for determining variations in corrosion rate. This method is based upon the concept that a change in the electrical conductivity of a thin metal strip reflects the corrosion which has occurred.
The effect of several common mineral contituents in water was determined. These include such impurities as chloride, sulfate, bicarbonate, carbonate, calcium, magnesium, and silicate. Of this group, it was found that chloride and sulfate are most detrimental to steel. No single impurity affects the corrosion of aluminum to the degree that mixed impurities do. A solution containing soluble salts of copper, chloride, and bicarbonate has an accelerating effect on the corrosion rate of aluminum. Pitting depends upon impurity concentration and temperature.
4.6.6, 6.4.2, 6.2.3
