Estudo da corrosão dos aços AISI 1010 e AISI 316L em soluções com elevado teor de cloreto e em ácido naftênico

• Ano de defesa: 2014
• Autor(a) principal: Cantarino, Surya de Jesus
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Mestrado em Química; Centro de Ciências Exatas; UFES; Programa de Pós-Graduação em Química
• Palavras-chave em Português: Oil Industry; Chlorides; Carbon steel; Stainless steel; Electrochemical analysis; Indústria petrolífera; Cloretos; Aço – Corrosão; Aço-carbono; Aço inoxidável; Análise eletroquímica; Química; 54
• Link de acesso: http://repositorio.ufes.br/handle/10/1269

The change in the oil global market in recent years, with declining reserves of light oil, have forced to search for new oil fields in more remote environments, such as in fields located in the pre-salt layer, and to the exploitation of heavy oils that have high content of naphthenic acids. This leads to major challenges for predicting the performance of materials in new environmental conditions in which they are. In the present work, the corrosion behavior of AISI 1010 carbon steel and AISI 316L stainless steel was studied in aqueous solutions with high chloride content and in cyclopentanoic naphthenic acid solution in order to better understanding the action of these species in the corrosion process and simulate corrosion by produced water in the oil industry. The techniques of open circuit potential, potentiodynamic polarization, cyclic voltammetry, electrochemical impedance spectroscopy, Raman spectroscopy, scanning electron microscopy and atomic force microscopy were applied according to convenience in each case. The increase in [Cl-] in the range of 1,2 to 2,8 mol.L-1 does not alter the cathode and anode processes near Ecorr for AISI 1010 and AISI 316L steels. Under conditions of overpotentials far from Ecorr, increasing [Cl-] increases oxidative corrosion processes, which is expressed by higher anodic current densities and anodic charge and increase of mass loss of the electrodes of both steels. Therefore, the damage of corrosion are more intense when increasing the [Cl-]. AISI 1010 steel is active in NaCl solutions and corrosion propagates freely in a generalized manner. For AISI 316L steel, a wide range of passivity can be seen in NaCl solutions; in Epit occurs the rupture of the passive film and growth of stable pitting. After 24 h immersion in sodium sulfate (white) and cyclopentanoic naphthenic acid solutions occurs growth of oxide film and the phase a-Fe2O3, Fe3O4 and d-FeO(OH) have been identified on AISI 1010 steel specimens and Fe3O4 identified in the defects of the prior oxide film present on AISI 316L steel surface. The films grown in cyclopentanoic acid solution have lower polarization resistance, higher roughness and greater corrosion rate compared to films grown in the blank solution, for both steels. The presence of naphthenic acid changes how the corrosion reaction is carried and contributes to increased corrosion. The naphthenic corrosion was more pronounced in carbon steel because the presence of alloying elements in stainless steel reduce the number of Fe rich active sites and become less opportune connection of Fe with the naphthenate.