Surface Oxidation of National Defense Stockpile Cobalt Does Not Adversely Affect Its Use

GAO was asked to examine the basis of a statement made by a former commissioner of the General Services Administration's (GSA) Federal Property Resources Service concerning oxidation of cobalt which was purchased in 1981 for the National Defense Stockpile. He stated that the cobalt met the purchase specifications in manufacture, but oxidized by the time it arrived in the United States, implying that the cobalt no longer met the purchase specifications.

GAO found that, between production and delivery time, the surface of the cobalt had oxidized. Cobalt is susceptible to oxidation at a variable rate, depending on factors such as temperature, humidity, and porosity. Furthermore, the cobalt had been acquired in a form which made surface oxidation likely. However, an industry study showed that surface oxidation should not adversely affect cobalt's use in the manufacture of defense-related superalloys, including moving parts such as turbine blades and discs in the hot end of aircraft engines. Surface oxidation presents no problems as long as the high-temperature alloy producers are aware of its presence in advance. Therefore, the former GSA commissioner's remarks were apparently misinterpreted regarding the possibility of accepting inferior quality cobalt for the National Defense Stockpile.