Corrosion inhibition of austenitic stainless steel by clay in polluted phosphoric acid with presence of SiC abrasif

Stainless steels have many properties mechanical and chemical resistances resulting from the formation of the protective layer (passive film) on their surface which prevents the metal to react with corrosive environments such as, phosphoric acid. This acid contains various impurities, including agressive agents and solid particles of gypsum, increase the risk of corrosion damage depending on the type of stainless steel used. In addition, it has been show that abrasion-corrosion causes an acceleration electrochemical process leading to a decrease in the resistance of materials. This work is to find a solution through an ecological inhibitor. That why we have been studied the effect of crude clay on corrosion behavior of Alloy 31 in polluted phosphoric acid with abrasive by electrochemical impedance spectroscopy (EIS) . The clay was characterized by X-ray fluorescence spectroscopy (FX), X-ray diffraction (DRX) and infrared spectroscopy (IR). EIS exhibited that resistance of Alloy 31 increased with increase the concentration of inhibitor

Chemical and Physical Effects of Fluoride on the Corrosion of Austenitic Stainless Steel in Polluted Phosphoric Acid

cited By 0International audienceThe effect of fluoride ions was investigated on the austenitic stainless steel in a typical solution of phosphoric acid that is used in industrial process, for clear understanding the damage that caused by corrosion to special alloying material Uranus B6 at temperature of 80 °C. For that the electrochemical and spectroscopy methods were used like potentiodynamic and electrochemical impedance spectroscopy, X-ray diffraction and UV–visible–IR reflection, Scanning electron microscopy and energy-dispersive spectroscopy analysis (SEM–EDX). The electrochemical methods show the drastic effect of fluoride on the passivation parameters, especially icrit, ipass and Epit caused by decreasing the alloy elements in the surface alloy, specially the molybdenum. Moreover, the spectroscopy results reflect that fluoride has two axes of interaction with the surface alloy; chemical interaction that was appeared by the dissolution mechanism, which it increases the dissolution of the base alloy atom and the alloying elements and this result was improved by the UV–visible–IR and EDX analysis. And the physical effect was demonstrated by X-ray diffraction, which is showing a deformation of the crystalline structure of surface alloy; and different pit types were detected by SEM. And the suggestion of the effect of fluoride on the nickel percent in the passive film and also on the molybdenum and copper has been proposed as a mechanism to explain these results. © 2019, Springer Nature Switzerland AG

Corrosion inhibition of austenitic stainless steel by clay in polluted phosphoric acid with presence of SiC abrasif

Stainless steels have many properties mechanical and chemical resistances resulting from the formation of the protective layer (passive film) on their surface which prevents the metal to react with corrosive environments such as, phosphoric acid. This acid contains various impurities, including agressive agents and solid particles of gypsum, increase the risk of corrosion damage depending on the type of stainless steel used. In addition, it has been show that abrasion-corrosion causes an acceleration electrochemical process leading to a decrease in the resistance of materials. This work is to find a solution through an ecological inhibitor. That why we have been studied the effect of crude clay on corrosion behavior of Alloy 31 in polluted phosphoric acid with abrasive by electrochemical impedance spectroscopy (EIS) . The clay was characterized by X-ray fluorescence spectroscopy (FX), X-ray diffraction (DRX) and infrared spectroscopy (IR). EIS exhibited that resistance of Alloy 31 increased with increase the concentration of inhibitor

Influence of temperature on alloy 31 in abrasion-corrosion conditions of phosphoric acid medium

cited By 0International audienceThe abrasion-corrosion behavior of the alloy 31 was tested at different temperatures 25 °C, 40 °C, 60 °C and 80 °C in polluted phosphoric acid medium. Electrochemical measurements were investigated using techniques such as electrochemical impedance spectroscopy and potentiodynamic polarization. In order to determine the oxides and hydroxides formed at the interface of the alloy, we opted for surface treatment techniques: SEM-EDX, UV-Vis-NIR spectroscopy, and X-ray diffraction. The results showed an increase in current densities, which means that these conditions favor the hydrogen evolution reaction and influence the parameters of the passive film. Moreover, this effect can be explained by an increase in the activity of the aggressive ions adsorbed on the surface, thereby accelerating the dissolution process and the exchange kinetics between the electrode surface and the electrolyte. UV-Vis-IR spectroscopy and X-ray diffraction analysis exhibited that temperature favors the formation of metal oxides on the surface, which the EIS discloses that film was less protective. © 2019 by CEE (Center of Excellence in Electrochemistry)

Effect of abrasive particles on electrochemical behaviour of passive film formed on Alloy 59 in contaminated phosphoric acid

cited By 2International audienceThe effect of abrasive on electrochemical behaviour of passive film formed on a austenitic stainless steel alloy 59 (UNS N-06059) in polluted phosphoric acid without and with abrasive grit was investigated by potentiodynamic and potentiostatic electrochemical measurements, electrochemical impedance spectroscopy and Mott-Schottky analysis. The results indicated that this alloy exhibited well passive behaviour with and without abrasive. In polluted phosphoric acid, the abrasion causes an electrochemical process acceleration leading to a decrease in the resistance and an increase in the capacity of material. The film formed on steel surface was of p-type and n-type semiconductors in the potential range below and above the flat band potential, respectively. The alloy 59 shows good resistance in the abrasion-corrosion according to his high chromium content, 22.65% Cr provided by the inner oxide film, while the outer film was more defective. © 2017, University of Mohammed Premier Oujda Morocco

Erosion–Corrosion Effect on the Alloy 316L in Polluted Phosphoric Acid

cited By 0International audienceThe physical factors such as the abrasive particles (AP) cause a mechanical rupture of the passive film in the polluted phosphoric acid. In this sense, the electrochemical methods and mass loss measurement were used to study the effect of these abrasive particles. X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy analysis (SEM/EDX) and UV–Vis–NIR spectroscopy methods were employed to analyze the material surface. The experimental results of X-ray diffraction showed that the AP affect the formation of passive film by decreasing the intensity of ferritic phases after 6 h of immersion. The measurements of polarization reveal that the erosion–corrosion accentuates the anodic dissolution of the material, which is manifested by an increase of the activation and passivity of current densities. The EIS exhibited a decrease in the polarization resistance of material caused by the reduction of the film thickness. The interpretation of the UV–Vis–NIR spectroscopy showed that the mechanical effect diminishes the passive film formation. In addition, the passive current density increases under the abrasion–corrosion condition which was approved by Mott–Schottky analysis. It is manifested by the formation of a porous outer layer and decrease in the properties of the inner layer, which was observed by UV–Vis–NIR and Mott–Schottky analysis, respectively. © 2019, Springer Nature Switzerland AG

An experimental-coupled empirical investigation on the corrosion inhibitory action of 7-alkyl-8-Hydroxyquinolines on C35E steel in HCl electrolyte

International audienceTwo 8-Hydroxyquinoline-based piperazine, 7-((4-(4-chloro phenyl)piperazin-1-yl) methyl) quinolin-8-ol (CPQ) and 7-((4-methyl piperazin-1-yl) methyl)quinolin-8-ol (MPQ) were prepared, identified and investigated as corrosion inhibiting additives of C35E steel in HCl electrolyte using experimental and theoretical tools. All outcomes findings confirm that CPQ and MPQ significantly improved anti-corrosion properties of C35E steel and CPQ performed better than MPQ and their inhibition efficiency depends on the temperature, the amount, and the chemical structure of the inhibitor. The ηmax of CPQ and MPQ reaches as much as 91.5% and 86.3% at 10−3 M, respectively. EIS outcomes revealed that the corrosion of C35E steel is controlled by only one charge transfer mechanism and the adsorbed CPQ and MPQ molecules decreased the steel dissolution by developing a pseudo-capacitive film on the steel surface. Both additives revealed mixed-type inhibitory activity, lowering of cathodic and anodic corrosion reactions rate, as proposed from the polarization investigation. The UV–Visible spectra suggest the existence of strong interaction between iron cations and 7-(4-alkylpiperazinylmethyl)-8-Hydroxyquinolines molecules. The 7-(4-alkylpiperazinylmethyl)-8-Hydroxyquinolines were chemisorbed on the C35E steel surface in accordance with Langmuir adsorption isotherm. Temperature influence studies of CPQ and MPQ adsorption behavior, as well as estimated thermodynamic magnitudes, are consistent with a physisorption process. The computational correlations (DFT, Monte Carlo, and Molecular Dynamic simulations) justify the experimental observations