Effect of aeration on Tafelian behavior of the carbon steel corrosion in acid sulfate medium/Efecto de la aireacion sobre el comportamiento tafeliano de la corrosion del acero al carbono en medio acido de sulfato

• Published in: Revista Facultad de Ingeniería 2017-06 (83), p.36
• Main Authors: Tamayo-Sepulveda, Jose Adrian, Vasquez-Arroyave, Ferley Alejandro, Calderon-Gutierrez, Jorge Andres
• Format: Article
• Language: Spanish
• ISSN: 0120-6230
• DOI: 10.17533/udea.redin.n83a05

This study presents a corrosion analysis of carbon steel by electrochemical polarization tests on a rotating disk electrode at several aeration and hydrodynamic conditions in solution 0.2 mol [L.sup.-1] [K.sub.2]S[O.sub.4] at pH 3. The reactions involved in the dissolution of the steel are analyzed by studying the Tafel regions of the polarization curves, confirming that the dissolved oxygen plays a predominant role in the corrosion of the metal. The corrosion rate was 35 times higher in natural aeration conditions than in the deaerated medium. Under natural aeration conditions, it is not possible to make a simple analysis of the corrosion of the steel from the extrapolation of the Tafel slopes since such slopes were not well defined due to the formation of rust in the anodic region and the influence of mass transport in the cathodic region. At cathodic polarization potentials and with natural aeration, there is an increase in polarization currents with respect to the deaerated system and the oxygen reduction reaction is controlled by the mass transport. Under deaerated conditions and at intermediate polarization potentials, there is a change in the dissolution mechanism of the steel. At high overpotential, the rate of dissolution of the steel tends to be equal in both systems, aerated and deaerated because the corrosion of the metal is controlled by the diffusion of species through corrosion products film. KEYWORDS Carbon steel, Tafel's law, corrosion, sulfate, oxygen diffusion Este estudio presenta un analisis de corrosion del acero al carbono mediante pruebas de polarizacion electroquimica en un electrodo de disco rotatorio en varias condiciones de aireacion e hidrodinamicas en solucion 0,2 mol [L.sup.-1] [K.sub.2]S[O.sub.4] a pH 3. Las reacciones implicadas en la disolucion del acero se analizan estudiando Tafel regiones de las curvas de polarizacion, lo que confirma que el oxigeno disuelto desempena un papel predominante en la corrosion del metal. La velocidad de corrosion fue 35 veces mayor en condiciones de aireacion natural que en el medio desaireado. Bajo condiciones de aireacion natural no es posible realizar un analisis simple de la corrosion del acero a partir de la extrapolacion de las pendientes de Tafel, ya que tales pendientes no estan bien definidas debido a la formacion de oxido en la region anodica y a la influencia del transporte de masa en la region catodica. En los potenciales de polarizacion catodica y con aireacion natural, hay un a