Growth and real time corrosion resistance monitoring of lead decanoate coatings

Lead is very susceptible to corrosion in the presence of organic acids and humidity. A potential countermeasure is to apply a lead carboxylate coating by immersing the metal in a sodium carboxylate solution/suspension. In this work we report on the degree of surface coverage and the corrosion resistance of a lead decanoate Pb(C₁₀)₂ coating as a function of treatment time. Results show that the surface coverage reaches 91% after 15 min and about 100% after 1 h in a 0.05 M sodium decanoate solution. The corrosion resistance, as indicated by electrochemical impedance spectroscopy, continues to increase even after 6 h of immersion. In addition, we show that in the case of planar transport, a diffusion layer of 17 mm thickness exists, wherein the sodium decanoate concentration drops linearly from its bulk value to almost zero at the solid/surface interface.