Influence of water composition and substrate on electrochemical scaling

Scaling of Fold, bronze, and stainless steel was investigated in synthetic fresh and seawater. It is shown that the calcium carbonate precipitation ra te increased from stainless steel, to bronze and then to gold whatever the composition of the scaling water. The morphology of the deposited scale dep ended on the substrate and on its surface state. For fast scaling, as with 200 mg dm(-3) Ca2+ carbonically pure water, calcite was mainly deposited: f or slower scaling vaterite was also observed. When foreign ions were added in the scaling water, aragonite appeared. In particular, for synthetic seaw ater, cc-here magnesium ions are highly concentrated, aragonite is preferen tially selected, so at the end of scaling aragonite covered the whole elect rode surface. The kinetic parameters, which characterize a precipitation mo del, were extracted from impedance measurements through a fitting procedure . The morphology of the precipitated calcium carbonate was examined by mean s of a scanning electron microscope. (C) 2000 The Electrochemical Society. S0013-4651 (99)07-108-6. All rights reserved.