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| Corrosion & Environmental Degradation |
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| Galvanic
Cells
· The diagram shows two metals, Copper and Zinc, each in equilibrium with its solvated ions at STP. The electrode potential for copper is +0.34 V and for zinc -0.76 V. · In open circuit, the voltmeter measures the sum of these two voltages, 1.10 V, each electrode behaving anodically with respect to its local electrolyte. · In closed circuit, a current flows between the two electrodes. Zinc behaves as the anode (supplying electrons) of the galvanic cell and the copper as the cathode (consuming electrons). The reactions occurring are those shown in the diagram. · The zinc electrode is dissolved (corroded or oxidized) and the copper electrode accepts copper atoms from the electrolyte (electroplating or reduction). This process continues as long as the circuit is closed. |
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| From:
Van Vlack,
"Elements of Materials Science and Engineering," Addison Wesley (1985) |
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