Reactions and Electrochemical Kinetics of Newly-Generated Metal Surfaces
Final rept. 1 Jul 1975-31 Aug 1976
ELECTROCHEMICAL TECHNOLOGY CORP SEATTLE WA
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Air Force flight vehicles must withstand increasingly complex environmental and operational regimes. Fundamental knowledge of the mechanisms of fatigue and fracture of flight structures is required. This research is related to the understanding of crack propagation, stress corrosion and corrosion fatigue in titanium and other metals. An electrochemical mass transport kinetic MTK model was previously formulated by the author to quantitatively describe the electrochemical events in a crack. It turned out that the model was not completely accurate because initial reactions on a newly- generated surface of titanium such as at the crack tip were not understood at that time. All electrochemical studies reported in the literature were for aged surfaces of titanium which had an oxide skin. The present work was done to fulfill the requirement of the model for quantitative data on new titanium surfaces and to develop a general understanding of the kinetics of the repassivation process. The MTK model is in process of revision to include titanium dissolution and formation of a salt film at the crack tip, based on the above experiments. Passivation kinetics of new surfaces of aluminum and zirconium were also determined.
- Physical Chemistry