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Unformatted text preview: Quiz 10 ENSC 3313, Spring 2002 Answer anv 4 Questions only, 1 point each Another text has a sketch of the microstructure of a Cu -40% Zn alloy in the corrosion chapter of the text. Tell why! 1. This is a 2-phase brass (a + ~). Thus we have 2 different phases in intimate contact and the possibility of microcells and galvanic corrosion. The zinc rich ~ phase would probably be the anode, recognizing that copper is more noble than zinc. For corrosion, required are two dissimilar materials, an electrolyte and electrical contact. So how come steel corrodes in the rebar of (say) bridge overpasses? Where do the 2 dissimilar materials come from? Where does the electrolyte come from? Why is it so potent? 2. Steel is a 2 phase alloy. The 2 phases, ferrite and iron carbide are in intimate electrical contact. Freeze-thaw cycles peffi1it ingress of moisture. The moisture often is high in chloride from de- icing treatments. The chloride ion disrupts protective coatings and enhances conductivity of theicing treatments....
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This note was uploaded on 01/10/2012 for the course ENSC 3313 taught by Professor Staff during the Fall '11 term at Oklahoma State.
- Fall '11