Search results for "Acer Corrosió"
showing 10 items of 10 documents
Thermogalvanic corrosion of Alloy 31 in different heavy brine LiBr solutions
2012
Thermogalvanic corrosion generated between two electrodes of Alloy 31, a highly-alloyed austenitic stainless steel (UNS N08031), has been investigated imposing different temperature gradients in three deaerated LiBr solutions, under open circuit conditions by using a zero-resistance ammeter (ZRA). Besides EIS spectra were acquired in order to explain the obtained results. On the whole, cold Alloy 31 electrodes were anodic to hot Alloy 31 electrodes, since an increase in temperature favoured the cathodic behaviour of the hot electrode. Thermogalvanic corrosion of Alloy 31 in the LiBr solutions studied was not severe, although it negatively affects the corrosion resistance of the cold anode. …
Improvement of the electrochemical behaviour of Zn-electroplated steel using regenerated Cr(III) passivation baths
2014
[EN] Conversion coatings based on trivalent chromium are more sensitive to the presence of zinc and iron impurities than the chromate formulations. This fact contributes to a decrease in the quality of passivation and to the generation of a significant amount of hazardous liquid waste. Recently, a new eco-innovative process based on Emulsion Pertraction Technology (EPT) is being implemented at industrial scale for selectively removing Zn and Fe from spent passivation baths in order to enhance the lifetime of the Cr (III) baths. In this study, the effect of Zn and Fe removal on the electrochemical behaviour of Zn-electroplated steel samples was evaluated by means of polarisation curves and e…
Study of Passive Films Formed on AISI 316L Stainless Steel in Non-Polluted and Underwater-Volcano-Polluted Seawater
2014
This work studies the semiconducting behavior of passive films formed on AISI 316L (UNS S31603) in two different sea-water solutions, non-polluted and polluted, collected from the volcano of El Hierro Island. Polarization measurements, potentiostatic passivation tests, electrochemical impedance spectroscopy, and capacitance measurements were performed. Results show that the polluted seawater worsens passivation kinetics. Additionally, passive films formed on AISI 316L stainless steel in polluted seawater have been found to be less protective than those formed in non-polluted seawater, showing a more defective structure, owing to the acidity of the polluted medium.
Comparison of the effect of non-polluted and underwater-volcano-polluted seawater on the corrosion resistance of different stainless steels
2015
This work compares the effect of non‐polluted and underwater‐volcano‐polluted seawater on the electrochemical behavior of two different alloys, notably an austenitic stainless steel (SS) and a duplex stainless steel. Polarization measurements, potentiostatic passivation tests, electrochemical impedance spectroscopy and capacitance measurements were performed. Results show that the composition of the polluted seawater negatively affects the passivation kinetics of both AISI 316 SS and Alloy 900, decreasing the corrosion resistance of both alloys. Additionally, when both steels are compared, it can be concluded that passive films formed on Alloy 900 presented better protective properties than…
Galvanic Corrosion Following Local Breakdown of a Scale Formed on X-65 in CO2 Saturated Solutions
2015
Under some conditions in sweet environments, the precipitation of corrosion products (primarily FeCO3) on the surface of X-65 pipeline steel can decrease the corrosion rate of the metal, this precipitated film acting like a protective scale. However, when these scales are damaged due to effects such as solidparticle erosion or mechanical stress, a galvanic pair can form between the bare steel (anode) and the surrounding undamaged scale (cathode). The aim of this work is to evaluate the magnitude of galvanic coupling that arises when the protective scale is broken and a corrosion cell is established between the defect and the surrounding scale. This study has been conducted in two stages: fi…
Passive and transpassive behaviour of Alloy 31 in a heavy brine LiBr solution
2013
The passive and transpassive behaviour of Alloy 31, a highly alloyed austenitic stainless steel (UNS N08031), has been investigated in a LiBr heavy brine solution (400 g/l) at 25 °C using potentiostatic polarisation combined with electrochemical impedance spectroscopy and Mott–Schottky analysis. The passive film formed on Alloy 31 has been found to be p-type and/or n-type in electronic character, depending on the film formation potential. The thickness of the film formed at potentials within the passive region increases linearly with applied potential. The film formed at transpassive potentials is thinner and more conductive than the film formed within the passive region. These observations…
Effect of Temperature on Thermogalvanic Coupling of Alloy 31 in Libr Solutions Studied by Means of Imposed Potential Measurements
2011
[EN] Corrosion resistance of Alloy 31, a highly alloyed stainless steel (UNS N08031) were studied in heavy brine LiBr solutions (400, 700 and 992 g/l) at different temperatures using electrochemical techniques. The mixed potential theory was used to evaluate thermogalvanic corrosion of Alloy 31 in the studied LiBr solutions. Potentiodynamic curves indicate that high temperatures favoured both cathodic and anodic processes, increasing passive current densities and decreasing the pitting potential. Generally, the cold electrode of the pair was the anode of the thermogalvanic cell.
Effect of temperature on the passive state of Alloy 31 in a LiBr solution: Passivation and Mott-Schottky analysis
2015
The passive behaviour of Alloy 31, a highly-alloyed austenitic stainless steel (UNS N08031), has been investigated in a LiBr heavy brine (700 g/l) at different temperatures using potentiostatic polarisation and Mott-Schottky analysis. Cation vacancies have been found to be the dominant defect in the passive films formed on Alloy 31. An increase in temperature enhanced the generation of cation vacancies at the film/solution interface and raised the steady-state passive current density. The density of defects within the passive film also increased significantly with temperature, making the film more conductive and less protective against localised attacks.
Passive Behavior and Passivity Breakdown of AISI 304 in LiBr Solutions through Scanning Electrochemical Microscopy
2014
The passive behavior and passivity breakdown of AISI 304 stainless steel in LiBr solutions has been investigated by means of scanning electrochemical microscopy (SECM). The sample generation - tip collection (SG-TC) mode was used to operate the SECM and the tip potential was biased to detect the electroactive species. The evolution of the current at the ultramicroelectrode tip with the applied potential within the passive range was followed at different LiBr concentrations. Results show that the absolute value of the current at the tip increases with the applied potential. Additionally, SECM was also used to detect stable pits formed on the stainless steel surface in a 0.2 M LiBr solution. …
Green approach to corrosion inhibition of stainless steel in phosphoric acid of Artemesia herba albamedium using plant extract
2019
Essential oil from aerial parts of Artemisia herba-alba from Morocco was hydrodistilled and its chemical composition oil was investigated by capillary GC and GC/MS. The major components were 1,8-cineole (35.6%) and camphor (24.1%). Artemisia herba-alba essential oil AHAO was tested as corrosion inhibitor of stainless steel (SS) in 1M H3PO4 using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy measurements (EIS) and scanning electronically microscopy (SEM) studies. The results obtained showed that the essential oil of Artemisia reduces the corrosion rate. Tafel polarization method indicates that the plant extract behaves as a mixed type inhibitor. The inhibition…