Electrochemical scaling of stainless steel in artificial seawater: Role of experimental conditions on CaCO3 and Mg(OH)2 formation
By Karoui, Héla; Riffault, Benoit; Jeannin, Marc; Kahoul, Abdelkarim; Gil, Otavio; Amor, Mohamed Ben & Tlili, Mohamed M.
Published in Desalination
2013
Abstract
In seawater, during the application of cathodic protection, a scale layer forms on the metal surface. As function of its chemical composition and compactness, it can improve the metal protection against corrosion by reducing the oxygen diffusion. The present investigation focuses on the electrochemical scaling of stainless steel in artificial seawater. Formed scales were characterized by X-ray diffraction, Raman spectroscopy and scanning electron microscopy. It was found that the formed scales are mainly CaCO3 aragonite. The brucite (Mg(OH)2) was identified, as a component of the scale layer, only for a high temperature and a more cathodic potential. It was also shown that, unlike other substrates, stainless steel promotes the precipitation of brucite. If the experimental conditions favoured its formation, the scaling process starts with brucite deposition. The growth of CaCO3 nucleuses, developed on interstice, recovers after brucite layer.