Steel In Sulfuric Solution Research Articles

An investigation on the utilization of a synthesized benzodiazepine derivative as a corrosion inhibitor for carbon steel in sulfuric solution: Chemical and electrochemical synthesis, surface analysis (SEM/AFM), DFT and MC simulation

The goal of this research is to investigate the corrosion inhibiting properties of a synthesized benzodiazepine derivative, 4-methyl-1,2-dihydro-3 H-benzo[b] [1,4] diazepin-3-one (MHBZO), in 0.5 M H2SO4 medium. Weight loss measures (WL), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) were used to evaluate the effectiveness of the MHBZO molecule. The organic molecule exhibits an interesting and effective anti-corrosion properties, with a maximum inhibitory efficacy (IE%) of 93.07% at 10−3 M. According to the results of the PDP, MHBZO operates as a mixed-type inhibitor. The temperature influence demonstrates that MHBZO is chemisorbed on CS. As the isotherm appears to fit the Langmuir model, MHBZO is monolayer adsorbed on the CS surface. The growth of a barrier film restricting the accessibility of corrosive ions into the CS surface is revealed by scanning electron microscopy (SEM) and atomic force microscopy (AFM), resulting in a smooth protected surface. Theoretical investigations were carried out to back up the experimentally obtained results.

Soybean extract firstly used as a green corrosion inhibitor with high efficacy and yield for carbon steel in acidic medium

The soybean extract (SE) was firstly investigated for corrosion inhibition characteristics on carbon steel in sulfuric medium. The weight loss and electrochemical methods were used to research the inhibition performance and adsorption properties of SE in combination with halide ions. Results showed the SE + I - inhibitors possessed outstanding corrosion inhibition efficiency, ~98%. Furthermore, the effective compound of SE was identified to be responsible for the corrosion inhibition effect. The AFM , water contact angle and XPS measurements confirm the formation of a corrosion inhibitor film on carbon steel. Combining differential capacitance curves, corrosion inhibition mechanism was further interpreted. Good inhibition efficiency, green extract solvent, facile extraction procedure, high yield and environment sustainability, endow SE as novel corrosion inhibitor with a promising future for industrial application. ● Soybean extract (SE) was firstly utilized as an eco-friendly, promising corrosion inhibitor. ● SE exhibited excellent inhibition efficiency (~98%) in combination with I - for carbon steel in sulfuric solution. ● Characteristic adsorption of I - would make for protonated SE adsorption on positively charged carbon steel surface.

In situ determinations of the wear surfaces, volumes and kinetics of repassivation: Contribution in the understanding of the tribocorrosion behaviour of a ferritic stainless steel in various pH

In tribocorrosion, the mechanic dominates the total wear. However, the corrosion wear should not be neglected for passive materials. As the film reactivity depends on pH, tribocorrosion experiments were performed on a ferritic stainless steel in sulphate solution (pH 1.5, 6.5 or 12.5). The passive film formation and degradation was evaluated through galvanic coupling tests while the degradation is quantified by image analysis. Wear results follows the Archard's law however, a non-linear dependence of the Archard's coefficient to the pH is found. The study of the worn surface reactivity highlights the role of the pH in the wear behaviour of the material as its influence on the film rebuilt kinetics and its contribution in the total wear.

Anodic Behavior of Steel in Sulfate-Rich Simulated Grout Pore Solution

Recent observations of severe corrosion of post-tensioned tendons in Florida Bridges were associated with segregated grout containing high sulfate ion concentrations (Lau et al, 2013). Generally, the role of sulfates for steel initiation in alkaline environments have not been well elucidated. In 1970, Gouda identified steel corrosion initiation in saturated calcium hydroxide solutions (pH=12.1) with sulfate concentrations greater than 0.2%; however, steel depassivation was not observed in concrete samples with sodium sulfate concentrations as high as 8%. Dehwah et al. 2002 reported that sulfates did not affect the time to chloride-induced corrosion initiation, but the corrosion rate increased with sulfate content. Research by Carsana and Bertolini in 2011 indicated a strong influence of solution pH on the anodic behavior of steel in sulfate solutions. The objective of the work presented here was to identify the role of early presence of sulfate ions on steel corrosion development. The experiments consisted of anodic polarization tests to determine the anodic behavior of steel samples exposed to alkaine solutions with pH 12.6 or 13.3. Those solutions contained sodium sulfate in the range of 0 to 20,000 ppm. The steel samples were preconditioned for 1 day at either the OCP condition or -1VSCE. The intent to pre-condition the sample at OCP was to initially allow any possible passive film growth to occur. The intent to cathodically pre-condition the steel sample at -1VSCE was to maintain the steel at a low corrosion rate but remaining at active corrosion condition prior to polarization. It this way, it was thought any adverse role of sulfate ions to impede stable passive film formation could be identified. Anodic polarization measurements were made initially from -1 VSCE to +500 mVSCE, with a slow scan rate (0.05 mV/s). Experimental results concluded that anodic polarization tests of steel in pH 13 solution with up to admixed 20,000 ppm sodium sulfate did not indicate strong tendency of sulfates to disrupt passive film formation. However, anodic polarization tests in pH 12.6 and admixed >4,000 ppm sulfate solution indicated instability of passive film resulting in pitting corrosion. It was observed that pH and admixed sulfate concentration will affect the stability of the passive layer. In some cases, as shown in Figure 1, anodic current excursions were indicative of localized depassivation. Indeed, some samples showed indications of pit development. This can be in part explained by the mechanism presented by Gavele (1976) where repassivation of pits can occur in the presence of increased sulfate concentrations within pits but may subsequently diffuse out leading to activation/passivation events. This change of a critical passivation sulfate concentration may result in the observed quick shifts in anodic current. More prominently however, the polarization graphs show transition from passive to active corrosion behavior of steel in solution with the admixed presence of 12,000 to 20,000 ppm sodium sulfate with anodic Tafel slope on the order of ~100 mV/dec. Figure 1

Inhibiting evaluation of β-Cyclodextrin-modified acrylamide polymer on alloy steel in sulfuric solution

The inhibiting performance of β-Cyclodetrin-modified acrylamide polymer (poly(AM-co-A-β-CD-co-NaAA)) on X70 steel in 0.5M H2SO4 solution has been investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The polarization curves results reveal that polymer acts as a mixed-type inhibitor. The inhibition efficiency is found to increase by increasing the polymer concentration up to maximum 84.9% for 150mgL−1 at 303K. The adsorption is confirmed to obey the Langmuir isotherm. The SEM and EDS results demonstrate that X70 surface is protected by β-Cyclodextrin-modified acrylamide polymer.

The Mechanism of Oxide Film Formation on AISI 316 Stainless Steel in Sulphate Solutions

Oxide film formation on AISI 316 stainless steel (a material often used for building nuclear reprocessing plants) in acidic and neutral sodium sulphate solutions is investigated using electrochemical and surface analysis techniques. It is found that the corrosion potential varies with pH in the amount of -55 mV / pH unit and critical currents increase with decreasing pH and increasing temperature in neutral solutions. The activation energy for the reaction in the active region is 45.6 kJ mol-1. Potentiostatic experiments indicate that three different film building processes are involved in film formation: the initial active-passive transition, the logarithmic growth of the film and the parabolic growth of the film. AES shows chromium enrichment at the surface, and ESCA gives little difference for the relative amount of Fe2+ and Fe3+ for 0.2 and 0.6 V. A theoretical model is being developed to account for the observed kinetics.

Kinetics of Film Growth on AISI 316 Stainless Steel in Sulfate Solutions

not Available.

The Mechanism of Oxide Film Formation on AISI 316 Stainless Steel in Sulphate Solutions

not Available.

Impedance of Cr18Ni10 stainless steel in sulphate solutions after a low‐temperature plasma nitriding

AbstractThe 00Cr18Ni10 stainless steel was examined before and after plasma nitriding in a 80%N2/20%H2 gas mixture at 425°C for 30 h, resulting in the formation of a supersaturated solid solution of nitrogen in austenite (S phase) with 12.9 wt.% N at the surface. Electrochemical measurements were made on the as‐nitrided surface and after abrasion to various depths. Polarisation curves and impedance were measured in 0.1 M Na2SO4 acidified to pH 3.0; some measurements were also made at pH 6 and 9. It was found that nitrogen decreased the corrosion resistance of the steel in the acidified solution (pH 3.0), but increased it in the neutral and near‐neutral solutions (pH 6.0 and 9.0). The deleterious effect of nitrogen at pH 3.0 was at potentials of the active state much stronger and more dependent on the nitrogen concentration than in the passive state. It was suggested that the increased anodic reactivity of the nitrided steel in the active state is inherent for the lower thermodynamic stability of the supersaturated solid solution of nitrogen, whereas the increased corrosion resistance in the neutral and near‐neutral sulphate solutions is associated with the effect of nitrogen on anodic films.

Hydrogen generation from a single crystal magnetite coupled galvanically with a carbon steel in sulfate solution

A galvanic coupling with a single crystal magnetite accelerated the corrosion of a carbon steel in sulfate solutions. A scanning electrochemical microscopic investigation revealed that the hydrogen generation on the magnetite as well as the reduction of the magnetite itself was contributed to a galvanic corrosion of the carbon steel. The estimated current efficiency for the hydrogen generation on the magnetite was about 50% in pH 5.8 sulfate solution. Moreover, the distribution of hydrogen generated above the magnetite surface was observed with the probe current image.

The Growth Mechanism of the Coloured Passive Film Formed on 304 Stainless Steel in Sulfuric Solution without Cr6+ ion by using A.V. Passivation

SUMMARYA thick passive film showing interference colours has been obtained on 304 stainless steel in sulfuric acid solution without Cr6+ ions by applying alternating square wave polarization. An investigation of the chemical composition and the distribution of valence states in the profile of the film has been carried out by using XPS. A mechanism for the colouring process is proposed

Pin-on-Disk Corrosion-Wear Test

Abstract An electrochemical pin-on-disk corrosion-wear apparatus was developed at the Albany Research Center of the U.S. Department of Energy. The instrument was qualified on a low-alloy T1 tool steel [ASTM A 514] and a 304 stainless steel (Type 304). The apparatus incorporates simple specimen and counterface geometry and is instrumented for simultaneous corrosion and wear testing. The electrochemical and wear parameters of potential, current, charge, sliding speed, frictional force, and normal acceleration can be continuously displayed and recorded. After a break-in period, the electrochemical pin-on-disk produced constant wear rates independent of path length for both ASTM A 514 steel and 304 stainless steel. Results for 304 stainless steel in sulfate solutions show that abrasive wear causes the corrosion potential to shift by 0.4 V in the active direction and the passive current density to increase by three orders of magnitude, compound with the condition of no wear. Current density was a linear function of the sliding speed at a constant applied anodic potential. The open circuit corrosion potential exhibits a decay function behavior with respect to the sliding speed. Volume loss and corrosion measurements showed that mechanical removal of material was responsible for 95% of the corrosion-wear losses for 304 stainless steel. Continual corrosion exposure, however, increased the mechanical removal of material by 35 to 48%.

Behaviour of Hastelloy C22 steel in sulphate solutions at pH 3 and low temperatures

The behaviour of Hastelloy C22 steel (N06022 UNS) in solutions at pH 3 and different temperatures, for radioactive water reprocessing plants was studied. The corrosion potential was found to increase with temperature. In the neighbourhood of the active-passive potentials, Hastelloy steel was corroded by means of a transient form. In addition, the potentials of the active and transpassive peaks shifted towards more negative values with increasing temperature. The transpassive peak increased with temperature and its potential shifted towards smaller values. The temperature increase led to a reduction of the passive region and a higher current in the passivity. As shown by current instabilities during the backward scan and a higher current than those in the forward transpassivity scan, all of the oxide layer could not be destroyed at the breakdown transpassive potentials. From electrochemical impedance spectroscopy (EIS), apparently the thickness of the passive oxide decreased with temperature in the prepassive region. In passivity, the EIS showed an enhancement of corrosion for higher potentials or temperatures. At the passivity-transpassivity limit potentials, an inductive loop may be the result of adsorption. It was found that the diameter of the capacitive semi-circle and the inductive loop decreased when the temperature increased, indicating an enhancement of corrosion and a decrease in adsorption. The number of active sites and oxidation rate were determined at different potentials.

Electrochemical behaviour and corrosion of 18-8 austenitic stainless steel in sulphate solutions

The electrochemical behaviour and corrosion of a commercial Egyptian 18-8 austenitic stainless steel was investigated in sulphuric acid and in sodium sulphate solutions using the potentiodynamic technique. In acid solution, the anodic polarization scans are characterized by the appearance of active, passive and transpassive transitions before oxygen evolution. The current densities corresponding to these three regions are increased by increasing either the acid concentration or the voltage scanning rate. The passive electrode does not regain its activity when subjected to cathodic treatment. Sensitization of the electrode enhances its susceptibility to intergranular corrosion. In sodium sulphate solution, the polarization scans are characterized by the disappearance of the active region. On sensitization, a second transpassive region appears before oxygen evolution.

Effect of some polyamino polycarboxylic acids on the corrosion of steel in sulphate solutions

The effect of the amino polycarboxylic acids, ethylene glycol-bis-(β-aminoethylether- N, N) tetraacetic acid, diethylenetriaminepentaacetic acid, ethylene diaminetetraacetic acid and nitrilotriacetic acid, on the corrosion behaviour of steel in pure H 2SO 4 and in Na 2SO 4 solutions of various pH values was studied by both weight loss and open-circuit potential measurements. It was shown that these organic substances behave bifunctionally; they inhibit the corrosion, presumably through adsorption in strong acidic media, and promote it above a certain pH value. The inhibition effectiveness is dependent on the molecular structure and the concentration of the organic substance. The promotion could be attributed to the formation and desorption of soluble complex ions.

ステンレス鋼の塩素イオンによる孔食発生

ステンレス鋼の塩素イオンによる孔食発生