1990 . 09 ELKIN , L . NAVAL POSTGRADUATE SCHOOL Monterey , California THESIS r CORROSION MECHANISMS AND BEHAVIOR OF A P - 130 X GR / 6063 AL COMPOSITE IN AQUEOUS ENVIRONMENTS

continue on reverse if necessary and identify by block number) The corrosion mechanisms and behavior of a P-130x graphite fiber reinforced 6063 aluminum composite laminate were udied. Electrochemical and total immersion tests were performed on the composite in 3.5% sodium chloride and 5.0% >dium sulfate solutions. The effects of pH, the presence of sulfite ions, various heat treatments, and electrolyte aeration were vestigated. Some tests were also performed on control monolithic 6063 aluminum specimens. Immersion tests showed that when graphite fibers are exposed simultaneously with the matrix, then galvanic coupling is e principal corrosion mechanism in this composite. However, if the composite cross sectional edges are sealed from contact tth the environment, then pitting attack of the surface foils becomes the principal mode of attack, especially in harsh envinments (chloride and sulfite ions present in addition to low pH). This form of attack can eventually lead to galvanic corsion. Low pH and the addition of sulfite ion significantly increase the susceptibility to localized corrosion and the rates of 3th general and galvanic corrosion. Progressive aging of the composite matrix decreases general corrosion rates in deaerated ilutions. Electrolyte aeration results in a significant reduction in the composite's resistance to all forms of corrosion. Distribution/Availability of Abstract unclassified, unlimited D same as report D DT1C users 21 Abstract Security Classification Unclassified a Name of Responsible Individual idranath Dutta 22b Telephone (include Area code) (408) 646-2851 22c Office Symbol ME/Du ) FORM 1473,84 MAR 83 APR edition may be used until exhausted All other editions are obsolete security classification of this page