UNIFORM AQUEOUS CORROSION OF ALUMINUM--EFFECTS OF VARIOUS IONS

The most important variable in water quality on the uniform corrosion of Al was the pH. Solutions of distilled water containing phosphate ions and citrate ions were the only media which showed a definite specific ion effect. Phosphate inhibited the corrosion and citrate increased it. Oxalate ions appeared to increase corrosion, but the effect is not definitely demonstrated by the data. Corrosion was dependent only on pH in tap water, reactor process water, distilled water, and distilled water containing up to 100 ppm of chloride, nitrate, sulfate, bicarbonate, hydrogen peroxide, acetate, arsenate, silicate, dichromate, molybdate, and mixtures of these ions. Solutions of up to 10,000 ppm chloride in distilled water showed no specific ion effect upon uniform Al corrosion. The effects of 0 to 10 ppm of dichromate and phosphate ions were investigated over the range pH 4 to pH 7. Phosphate at 10 ppm inhibited corrosion in solutions containing up to 2 ppm of dichromate, but at 10 ppm dichromate the phosphate does not appear to inhibit corrosion. Also at 10 ppm dichromate, the effect of pH is diminished over the range pH 4 to pH 7. Corrosion rates varied with the flow rates of the test solutions at low flow rates, and were lowest at the lowest flow rates. This effect was attributed to the buildup of aluminate ion conconcentration in the lower flow systems. Short term corrosion tests at 92 deg C revealed major specific ion effects. Minor effects were lost in experimental uncertainties. The inhibiting effect of phosphate under these conditions has been shown to exist over longer exposures at higher temperatures. (auth

Hanford Works Report HW-43085

The introduction of aluminum in hot process water has been studied extensively and numerous reports have been issued on the subject. The conclusions reached have been largely empirical and can only be used to state what is happening under the given conditions existing in the corrosion experiments. It is only with difficulty and a great deal of uncertainty that these empirical results can be used to predict what will occur under a different set of conditions. If the fundamental mechanism of aluminum corrosion in water were known, it is possible that more accurate predictions could be made and that steps might be taken to affect the controlling factors and thus reduce the severity of corrosion. To keep the system as simple as possible one would attempt to study the corrosion mechanism by corroding aluminum in pure water. However, this is undesirable because of the extremely low corrosion rate of aluminum in pure water and the large water supply and treatment facility required to supply sufficient high purity water for circulation about the corrosion samples

An automatic recording thermobalance /

"HW-41007 ; Chemistry ; (TID-4500, 10th Ed.).""January 20, 1956."Includes bibliographical references (p. 18).Operated for the Atomic Energy Commission by the General Electric CompanyMode of access: Internet

Hydriding of zirconium and uranium in organic coolants /

"November 12, 1958."Bibliographical references: p. 18.Work performed between the Atomic Energy Commission and General Electric CompanyMode of access: Internet