Seattle Distribution System Corrosion Control Study. Volume 6. Use of a Rotating Disc Electrode to Assess Copper Corrosion

摘要

The uniform corrosion of copper tubing used for transport of Tolt River water is characterized in this study as a heterogeneous rate process composed of metal oxidation and oxide film growth, interfacial chemical reactions, and mass transport in the liquid phase. Quantitative rate expressions were developed to characterize each of these rate processes. Experiments designed to measure the temperature and pH dependence of corrosion under rate control by each process were conducted using steady-state electrochemical techniques. The persistent and unexpected influence of solution transport of a reaction produce, presumed to be OH-, complicated characterization and identification of underlying rate process. Surface pH could be characterized empirically as a function of solution temperature, pH, and diffusion layer thickness. Steady-state electrochemical techniques gave rapid, reliable, and reproducible corrosion rate measurements and provided the versatility necessary to characterize quantitatively a heterogeneous rate process like aqueous copper corrosion.