Characterising the quality of chemical tin coatings on copper by electrochemical current noise method

The electrochemical current noise method is widely applied for characterising the surface phenomena of bulk metals or polymer-coated metals. No studies, however, have been available on its use for the characterisation of metallic coatings. This study explores the potential of electrochemical current noise measurements to characterise the quality of chemical tin coatings on the inner surface of copper tubes. The study is carried out by using scanning electron microscopy (SEM), open circuit potential surveys and actual electrochemical current noise measurements. The results obtained by electrochemical current noise measurements were consistent with the microstructural examination and thermodynamical corrosion studies of chemical tin coatings on copper. The statistical analysis of electrochemical current noise data presented either in time or in frequency mode is capable of characterising the chemical tin coatings in terms of uniformity, surface morphology and porosity. The peak shapes of current noise transients reflect the electrochemical phenomena taking place in the tin coating–copper system exposed to drinking water.