Corrosion Kinetics of Iron in Acid Sulfate Solutions

Barnartt, Sidney

doi:10.1149/1.2404346

Cited by 28 publications

(11 citation statements)

References 10 publications

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“…In the deaerated system the values of the calculated Tafel slopes are βc = 300 and βa = 125 mV/dec, for the cathodic and anodic reactions, respectively. Usually, values around of 100 mV/dec and 60 mV/dec have been reported for the cathodic and anodic Tafel slopes for pure iron corrosion in acid sulfate solutions [16][17][18]. The difference with respect to the values obtained in the present work can be due to the small quantities of alloying elements present in the steel, which can influence in a remarkable way the kinetics of the dissolution of the iron [17,19].…”

Section: Effect Of Aeration On the Polarization Curves Of Carbon Steecontrasting

confidence: 66%

“…Usually, values around of 100 mV/dec and 60 mV/dec have been reported for the cathodic and anodic Tafel slopes for pure iron corrosion in acid sulfate solutions [16][17][18]. The difference with respect to the values obtained in the present work can be due to the small quantities of alloying elements present in the steel, which can influence in a remarkable way the kinetics of the dissolution of the iron [17,19]. In the anodic region under deaerated system, the Tafel slope corresponding to the iron dissolution reaction (Eq.…”

Section: Effect Of Aeration On the Polarization Curves Of Carbon Steementioning

confidence: 99%

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Effect of aeration on Tafelian behavior of the carbon steel corrosion in acid sulfate medium

Sepúlveda

Vásquez

Gutiérrez

2017

Rev. Fac. Ing. Univ. Antioquia

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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 -1 K 2 SO 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. RESUMEN:Este estudio presenta un análisis de corrosión del acero al carbono mediante pruebas de polarización electroquímica en un electrodo de disco rotatorio en varias condiciones de aireación e hidrodinámicas en solución 0,2 mol L -1 K 2 SO 4 a pH 3. Las reacciones implicadas en la disolución del acero se analizan estudiando Tafel regiones de las curvas de polarización, lo que confirma que el oxígeno disuelto desempeña un papel predominante en la corrosión del metal. La velocidad de corrosión fue 35 veces mayor en condiciones de aireación natural que en el medio desaireado. Bajo condiciones de aireación natural no es posible realizar un análisis simple de la corrosión del acero a partir de la extrapolación de las pendientes de Tafel, ya que tales pendientes no están bien definidas debido a la formación de óxido en la región anódica y a la influencia del transporte de masa en la región catódica. En los potenciales de polarización catódica y con aireación natural, hay un aumento en las corrientes de polarización con respecto al sistema desaireado y la reacción de reducción de oxígeno es controlada por el transporte de masa. Bajo condiciones desaireadas y en potenciales de polarización intermedios, hay un cambio en el mecanismo de disolución del acero. A altos sobrepotenciales, la velocidad de disolución del acero tiende a ser igual en ambos sistemas (aireado y desaireado), porque la corrosión del metal es controlada por la difusión de especies a través de la película de productos de corrosión.

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Section: Effect Of Aeration On the Polarization Curves Of Carbon Steecontrasting

confidence: 66%

Section: Effect Of Aeration On the Polarization Curves Of Carbon Steementioning

confidence: 99%

Effect of aeration on Tafelian behavior of the carbon steel corrosion in acid sulfate medium

Sepúlveda

Vásquez

Gutiérrez

2017

Rev. Fac. Ing. Univ. Antioquia

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“…The reverse reactions of the last two equations (2) or (3) occur at an insignificant rate at low pH. The rate of reaction (2), expressed as current I at potential Є, is known to follow the Tafel equation (25) :…”

Section: I-concentration Effect: I-effect Of Free Hci Concentration O...mentioning

confidence: 99%

“…certain potential and correspondingly increases the corrosion rates, while Ecorr was unchanged (Figure 9 and Table 5). It was suggested that the critical factor in corrosion process is the rate at which a metal surface repassivates after the original passive film has been ruptured by slip-step emergence, etc (25) . Therefore, at higher temperatures, metals in the potential regions near the active-passive (42) where the surface is still filmed but the impetus for passive film renewal is somewhat slow should be more susceptible to corrosion.…”

Section: E M Attia and F H Abd El-salammentioning

confidence: 99%

The Effect of Triazole Thione Derivative on the Corrosion of Iron in Hydrochloric Acid Solutions

2009

Al-Azhar Bulletin of Science

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Surfactant; N-(sodium-2-hydroxy-3-sulphato propyl)-5-stearyl-1,3,4-triazole-2-thione (18PTT) was tested as a corrosion inhibitor for iron electrode in hydrochloric acid media using potentiodynamic polarization measurements. Results obtained show that the corrosion rate (CR) increases with increasing of free acid concentration. In the presence of the inhibitor, the magnitude of CR is suppressed as its tendency to increase with acid concentration. The changes in the electrochemical parameters with concentration of surfactant studied are indicative of the adsorption of surfactant leading to the formation of a protective layer on the surface of iron. The inhibition efficiency (IE %) increases with an increase in concentration of surfactant and hydrochloric acid but decreases with temperature. This surfactant suppressed both cathodic and anodic processes of iron corrosion in HC1 solution by adsorption on iron surface according to Langmuir adsorption isotherm but affecting more the anodic reaction than the cathodic one. Thus, it can be classified as mixed-type inhibitor. The thermodynamic parameters for the dissolution of the metal and for the adsorption of the inhibitor on the metal surface were calculated and discussed. In the range of 20-60 °C corrosion rates were found to increase with increasing temperature for inhibited and uninhibited acid solutions, while corrosion potential (Ecorr) was unchanged. The associated apparent activation corrosion energy (Ea) has been determined and found to be higher in presence than in absence of the inhibitor. The calculated thermodynamic parameters (∆G°), (∆H°) and (∆S°) showed that the inhibition process is spontaneous and exothermic in nature.

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“…The corrosion current densities, i , , , were calculated from these Rp, pa and p, values according t o Eq. (7) for each measuring point. Then they were averaged gfaphically for the entire immersion periods and compared with that calculated from the weight losses of the same test pieces ( Table 2).…”

Section: Mild Steel In Neutral Solutionsmentioning

confidence: 99%