Permeation Current Research Articles

Hydrogen permeation behavior and corrosion monitoring of steel in cyclic wet–dry atmospheric environment

AbstractHydrogen permeation of 16Mn steel under a cyclic wet–dry condition was investigated by Devanathan–Stachurski's electrolytic cell with a membrane covered on the exit side by a nickel layer and the weight loss was measured for each wet–dry cycle. The results show that hydrogen permeation current change with different atmospheric environment: distilled water, seawater, and seawater containing 100 ppm H2S. The results show that seawater can induce an increase in the hydrogen permeation current due to the hydrolyzation reaction. And after the increase, equilibrium is reached due to the equilibrium of hydrolyzation reaction effect and the block of the rust layer. On the other hand, H2S contamination also can induce an increase in the maximum hydrogen permeation current due to the hydrolyzation reaction. And H2S contamination delays the time that hydrogen permeation is detected because of the formation of the FeS(1−x) film. The FeS(1−x) film can block the absorption of hydrogen onto the specimen surface. The surface potential change and the pH change of the metal surface control the hydrogen permeation current. And a clear linear correlation exists between the quantities of hydrogen permeated through the 16Mn steel and the weight loss. Based on the linear correlation, we monitored the corrosion rate by monitoring the hydrogen permeation current by a sensor outside. Good coherences were shown between results in laboratory and outside.

Effect of N-cetyl-N,N,N-trimethylammonium bromide and orthophenylenediamine on the corrosion inhibition of carbon steel in 1 mol/L HCl

Inhibition studies of N-cetyl-N,N,N-trimethylammonium bromide (CTAB) and orthophenylenediamine (OPD) have shown that they were effective inhibitors of corrosion of carbon steel in HCl. The inhibitive behaviour of OPD with CTAB on the corrosion of carbon steel in 1 mol/L HCl was studied by gravimetric weight loss, potentiodynamic polarization, and electrochemical impedance measurements. Inhibition efficiency (IE) was found to increase with the increase in concentration of CTAB and it was also found that CTAB was effective only when used above a concentration of 100 mmol/L. Furthermore, the addition of 20 mmol/L of OPD to CTAB slightly increased the IE. The adsorption of these compounds on carbon steel in 1 mol/L HCl obeyed Langmuir's adsorption isotherm. These inhibitors reduced the permeation current. The IE was observed as high for 200 mmol/L of CTAB with 20 mmol/L of OPD in all the techniques studied. Scanning electron microscopy clearly showed that the inhibition was due to a polymolecular film formed by the physical adsorption of the inhibitor on the metal surface.Key words: carbon steel, corrosion, inhibitors, impedance, potentiodynamic polarization.

The role of iron in the prevention of nickel electrode deactivation in alkaline electrolysis

There is some uncertainty concerning the role of iron deposits on the surface of nickel electrodes with respect to electrode activity during alkaline water electrolysis. Iron deposits variously have been reported to enhance nickel electrode activity by providing additional surface area from electrolytic deposition of solution phase iron species or to depassivate nickel electrodes via a surface interaction effect. In this study, nickel electrodes were sputtered with a smooth iron layer to determine the effect of metallic iron on the electrode surface without significantly changing the electrode surface area. A permeation cell with 8 mol/L KOH at 70 °C was used to follow nickel electrode potentials during hydrogen evolution while the permeation current was used to detect changes in the electrode structure. Short term measurements reveal no difference in behavior of coated and non-coated electrodes. Longer term results showed that a metallic iron coating on nickel electrodes prevented deactivation of the electrodes. The deactivation effect was associated with an increased hydrogen flux through the electrodes indicative of an elevated hydrogen concentration at the electrode surface. This high surface concentration is concluded to be the result of nickel hydride phase formation at the surface of the nickel electrodes. The iron coating prevents this surface phase from forming and hence prevents deactivation of the electrode.

Fundamentals of hydrogen evolution reaction and its implications on near-neutral pH stress corrosion cracking of pipelines

In this work, electrochemical techniques were utilized to investigate the hydrogen evolution reaction on X-70 pipe steel and the hydrogen permeation through the steel in near-neutral pH environmental condition. The results demonstrate that the steel has always been in an active-dissolution state in near-neutral pH solution and there is no film formed on the steel surface. Hydrogen evolution is inhibited by anodic polarization of the steel, which is attributed to the alternation of hydrogen evolution mechanism and kinetics on the anodially polarized steel. Combined with slow strain rate tensile tests, it is found that the high susceptibility of steel to stress corrosion cracking (SCC) is always associated with a high hydrogen permeation current. A thermodynamic model was developed, by analyzing the change in free-energy of the steel in the presence and absence of hydrogen and stress, to determine the interactions of hydrogen, stress and anodic dissolution at the crack-tip. The role of hydrogen involvement in pipeline near-neutral pH SCC could be determined quantitatively by characterizing the effect of hydrogen concentration on the dissolution rate of steel and the synergism of hydrogen and stress to promote crack growth.

Analysis of electrochemical hydrogen permeation through X-65 pipeline steel and its implications on pipeline stress corrosion cracking

Electrochemical hydrogen permeation tests were performed to measure the hydrogen permeation current through the X-65 pipeline steel in the electrolytes simulating the soil conditions to initiate near-neutral pH stress corrosion cracking (SCC) in pipelines. The hydrogen permeation current was analyzed following the constant concentration model. It is shown that, AQDS, simulating the organic compound in the soil, inhibits hydrogen permeation by decreasing the sub-surface hydrogen concentration, while sulfide promotes hydrogen permeation by inhibiting the hydrogen recombination and thus increasing the sub-surface hydrogen concentration. The steel specimen is more susceptible to stress corrosion cracking in the soil solution with a higher sub-surface hydrogen concentration, indicating that hydrogen is involved in near-neutral pH SCC in pipelines. It is suggested that hydrogen promotes the cracking of the steel, accompanying with the anodic dissolution on the crack sides and at the crack tip.

Hydrogen permeation in gamma titanium aluminides

The permeation of hydrogen in gamma titanium aluminides was studied using the Devanathan–Stachurski (DS) cell. Thin disk-shaped samples of gamma titanium aluminide with three different microstructures were appropriately prepared and cathodically charged in an aqueous 0.1 N NaOH solution. The permeation current was monitored as a function of time. Permeation parameters were calculated using the time lag criterion (non-steady state lag). Values of the apparent diffusion coefficient of hydrogen in gamma titanium aluminide varying from 1.87 × 10 −7 cm 2/s to 3.75 × 10 −6 cm 2/s were obtained. This slight variation is attributed to differences in microstructure.

Sulphide stress cracking behaviour of weldments produced by indirect electric arc welding

The aim of the present study was to evaluate the corrosion resistance of weldments produced by the Indirect Electric Arc technique. The material studied was API grade X-65 steel, which was corroded in NACE solution saturated with H2S. Three different temperatures were employed, room temperature (25°C), 37°C and 50°C. The test methods used included potentiodynamic polarisation curves, hydrogen permeation measurements and slow strain rate tests. The anodic corrosion current density and sulphide stress cracking susceptibility of the weldments were found to be unaffected by temperature over the range 25–50°C. However, values of the steady-state hydrogen permeation current, hydrogen permeation rate, effective diffusion coefficient, and the concentration of hydrogen atoms at the entrance side all increased with temperature. The cracking of the X-65 weldments is explained in terms of a hydrogen embrittlement mechanism.

Influence of tensile straining on the permeation of hydrogen in low alloy Cr–Mo steels

The effect of dynamic tensile straining on hydrogen permeation through low alloy Cr–Mo steel samples was studied with the electrochemical permeation technique. The hydrogen steady-state permeation current through large flat tensile specimens mounted between the two compartments of an electrochemical permeation cell undergoes different types of changes, depending on the charging conditions, on the steel’s composition and microstructure and on the strain rate. Dynamic trapping of hydrogen to strain-induced dislocations which leads to a deviation of the permeation current below the initial steady-state value is mostly observed when the external hydrogen activity and the strain rate are large. However, the hydrogen permeation current through Cr–Mo steels with a bainitic microstructure appears to be less sensitive to tensile straining up to large deformation levels than a lower alloyed Cr–Mo steel with a ferrito-pearlitic microstructure. On the other hand, the enhancement of the steady-state hydrogen permeation current observed during tensile straining if specific experimental conditions are met strongly suggests a mechanism of hydrogen transport by mobile dislocations which contributes to hydrogen permeation.

A Study of Microbiologically Induced Corrosion by Sulfate-Reducing Bacteria on Carbon Steel Using Hydrogen Permeation

Abstract The mechanism of microbiologically influenced corrosion (MIC) on carbon steel (CS) by the bacteria Desulfovibrio desulfuricans subs. desulfuricans was studied using hydrogen permeation, open-circuit potential, and cathodic polarization techniques, in a concentrated culture medium containing bacteria cells (107 cell/mL) and ferrous ions (300 mg/L) designed to simulate a condition common in systems for the secondary recovery of crude oil, characterized by highly contaminated microenvironments that severely corrode iron alloys in a short time period. This research project was carried out using several 24-h experiments to define initial stages of the corrosive process under the conditions indicated. The results evidenced a hydrogen permeation current peak of about 12 μA correlated with a minimum open-circuit potential of −780 mV vs saturated calomel electrode (SCE), 400 min after inoculation. Next, the permeation current decreased abruptly to its base line and the potential increased, stabilizing at ...

Aldimines – Effective Corrosion Inhibitors for Mild Steel in Hydrochloric Acid Solution

New and effective aldimine types of corrosion inhibitors namely, N-methylidene octylamine (MOA), N-ethylidene octylamine (EOA) and N-propylidene octylamine (POA) have been synthesized. Their inhibition efficiency was investigated for the corrosion of mild steel in 1 M HCl solution by various corrosion monitoring techniques. A preliminary screening of the inhibition efficiency of the inhibitors was carried out by weight loss and gasometric studies. They were found to behave as good inhibitors in 1 M HCl solution. Potentiodynamic polarization measurements show that aldimines are mixed type inhibitors. The extent of the decrease in the hydrogen permeation current through the mild steel surface was studied by the hydrogen permeation technique and it was found that the decrease was in the order POA > EOA > MOA. Double layer capacitance and charge transfer resistance values were derived from Nyquist plots obtained from AC impedance studies. The adsorption of these compounds on mild steel from 1 M HCl solution obeys the Temkin adsorption isotherm.

Inhibiting effects of some mercapto-triazole derivatives on the corrosion of mild steel in 1.0 M HCl medium

The effect of some mercapto-triazole derivatives synthesized in the laboratory containing different hetero atoms and substituents in the organic structures on the corrosion and hydrogen permeation of mild steel in 1.0 M HCl was investigated by weight loss and various electrochemical techniques. Results obtained reveal that all the mercapto-triazole derivatives perform excellently as corrosion inhibitors for mild steel in 1.0 M HCl. Potentiodynamic polarization studies have shown that all these compounds suppress both the anodic and cathodic process and they behave as mixed-type inhibitors. Double layer capacitance and charge transfer resistance values were derived from Nyquist plots obtained from AC impedance studies. Changes in impedance parameters are indicative of the adsorption of these compounds on the metal surface. The inhibition efficiency mainly depends on the nature of the investigated compounds. The values of the inhibition efficiency calculated from these techniques are in reasonably good agreement. The extent of reduction of hydrogen permeation current through mild steel surface was studied by the hydrogen electropermeation technique. The adsorption of these compounds on mild steel surface is found to obey Langmuir adsorption isotherm. The free energy of adsorption for inhibiting process was determined on the basis of Langmuir adsorption isotherm.

Estudio de la teoría de despolarización catódica con permeación de hidrógeno y la bacteria <i>Desulfovibrio desulfuricans</i>

A Desulfovibrio desulfuricans ssp. desulfuricans (SRB) was used to study the permeation of hydrogen, using a Devanaran and Stachurski cell and a palladium sheet. The aim was to evaluate cathodic depolarization as a Sulfate-Reducing Bacteria action mechanism in Microbiologically Induced Corrosion. The permeation tests were run with and without cathodic polarization, using a sterile deaerated culture medium inoculated with 10 % SRB concentrated at 10 8 cel/ml. The results indicate bacterial growth in the order of 10 9 -10 10 cel/ml after 18 h both in the polarized and non-polarized tests, indicating that SRB developed regardless of the surface polarized as a source of H 0 , generating H 2 S as a product of the anaerobic respiration. It was also determined that, without cathodic polarization, the conditions are not enough to reduce the H + generated by the H 2 S dissociation (Pd is not susceptible to corrosion at this condition). On the other hand, cathodic polarization increased the permeation current, which was associated with the maximum enzymatic activity phase of the bacteria.

Development of Scanning Laser-Enhanced Electrochemical Microscopy for Visualizing Hydrogen Distribution on a Steel

A Scanning Laser-Enhanced Electrochemical Microscope for Hydrogen detection (H-SLEEM) has been developed in order to in-situ visualize the distribution of hydrogen localized on a steel surface. Introduction and detection of hydrogen for the steel sheet was conducted by hydrogen permeation technique with a pair of electrochemical cells. When the hydrogen detection side under hydrogen permeation is irradiated with focused Ar laser, anodic current relating to hydrogen oxidation reaction is thermally enhanced at the irradiation spot and then anodic current increment corresponding to the hydrogen permeation rate at the spot is expected to be determined. In the case that whole the hydrogen detection side was irradiated with diffused laser, the anodic current increased and the current increment increased with an increase in the hydrogen permeation current. The use of focused laser also permitted the measurement of the anodic current increment depending on the hydrogen permeation current. The modulated laser provided more stable and reproducible current increment. When the specimen whose hydrogen entry side was masked except for a small exposed area in center was employed and the modulated laser was raster-scanned under hydrogen permeation, a very clear image of the two-dimensional distribution in the current increment corresponding to local hydrogen permeation rate on the detection side was obtained. it is concluded that the H-SLEEM can successfully visualize the localized hydrogen distribution on the steel surface.

Influence of alloying additives on corrosion and hydrogen permeation through commercial aluminium in alkaline solution

The influence of alloying additives on the extent of corrosion and hydrogen permeation through aluminium of different grades such as 2S, 3S, 26S and 57S, in 0.01 M NaOH has been investigated using weight loss measurements and electropermeation. It is found that the extent of self corrosion and hydrogen permeated through different grades of commercial aluminium follow the order: 3S > 2S > 26S > 57S. The influence of incorporating zinc and indium either alone or in combination on self corrosion and permeation current has also been studied. It is found that ternary alloys of both 26S and 57S containing zinc and indium give considerably lesser values of self corrosion rate and permeation current.

Development of a New Electrodeposition Process for Plating of Zn‐Ni‐X (X = Cd, P) Alloys Permeation Characteristics of Zn‐Ni‐Cd Ternary Alloys

It is shown that an electrodeposited Zn‐Ni‐Cd alloy coating produced from sulfate electrolyte inhibits the discharge of hydrogen on carbon steel. The newly developed ternary alloys have approximately ten times higher corrosion resistance when compared to a Zn‐Ni alloy. Hydrogen permeation characteristics of Zn‐Ni‐Cd alloy coatings were studied and compared with those of a bare and a Zn‐Ni alloy coated steel. The transfer coefficient, α, exchange current density, , thickness dependent adsorption‐absorption rate constant, k″, recombination rate constant, , surface hydrogen coverage, , were obtained by applying a mathematical model to experimental results. Alloys obtained from baths containing higher concentration than 3 g/L of in the sulfate plating bath are seen to have superior permeation inhibition properties compared to the Zn‐Ni alloy coating and bare steel. The hydrogen permeation current was zero under normal corroding conditions for Zn‐Ni‐Cd alloy and it increased to at a cathodic overpotential of 250 mV. The hydrogen permeation current density for steel and Zn‐Ni alloy under similar conditions were 62.1 and , respectively. © 2000 The Electrochemical Society. All rights reserved.

Effect of piperidones on hydrogen permeation and corrosion inhibition of mild steel in acidic solutions

The influence of 3-methyl-2,6-diphenyl piperidin-4-one (MDPO) and 2-phenyl decahydroquinoline-4-one (PDQO) synthesised in the laboratory on hydrogen permeation and corrosion inhibition of mild steel in 1N H2SO4 has been studied using weight loss and various electrochemical AC and DC corrosion-monitoring techniques. Both the compounds inhibit the corrosion of mild steel in H2SO4. Potentiodynamic polarisation studies clearly reveal that they behave predominantly as cathodic inhibitors. The extent of decrease in hydrogen permeation current through steel surfaces has been studied by the hydrogen electropermeation technique. Double layer capacitance (C dl ) and charge transfer resistance (R t ) values are derived from Nyquist plots obtained from AC impedance studies. The adsorption of these compounds on mild steel surfaces from H2SO4 obeys Temkin’s adsorption isotherm.

SCC inhibition of a C-steel in acidic 5% NaCl solutions in the presence of thiosulphate

The inhibiting effect of some organic compounds on the stress corrosion cracking (SCC) of a C-steel in 5% NaCl+0.5% acetic acid in the presence of 1 mM thiosulphate at 25°C was studied. The examined compounds at 0.1 mM concentration were: n-dodecylquinolinium bromide (DDQB), n-dodecylpyridinium chloride (DDPC), benzyl,stearyl,dimethylammonium chloride (BSDMAC), 1-(2-amminoethyl)-2 n-tridecyl-3 imidazoline (IMI-13), 2- n-hexyl-3 imidazoline (IMI-6), 2- n-tridecyl-3-imidazoline (IMI), N-phenyl-cinnamyliden-imine (PH-ATC). The inhibition of these compounds on the uniform corrosion was evaluated by recording anodic and cathodic polarisation curves after 1 and 24 h immersion of the electrode in the aggressive solutions. Slow strain rate tests were performed at a strain rate of 1×10 −6 s −1. The SCC susceptibility degree ( α) was evaluated by the ratio between percentage elongation to fracture in the test solution and that in air. The hydrogen permeation currents after 24 h of immersion of steel were determined. The examined compounds exerted an inhibiting action towards the general corrosion, ranging between 74 and 96%. The percentage inhibiting efficiencies (IE), calculated from the permeation current values of DDQB, DDPC and IMI, were almost the same as the percentage IE towards the general corrosion. In the presence of the other compounds percentage IE on the hydrogen permeation was lower than that towards the general corrosion. DDQB, DDPC and IMI were able to reduce the stimulating action of thiosulphate completely. The other compounds increased α values, but they were unable to inhibit SCC completely. The inverse linear relationship between α and hydrogen permeation current values evidenced a strict correlation between hydrogen permeation and SCC susceptibility in these solutions.

Influence of nitrones on corrosion inhibition and hydrogen permeation through mild steel in acidic solutions

A few nitrones such as N‐benzilidene aniline‐N‐oxide, N‐(O‐hydroxy benzilidene) aniline‐N‐oxide (HN) and N‐(α‐naphthylidene) aniline‐N‐oxide (NN) have been synthesised and investigated for evaluating their efficiency as inhibitors for the corrosion of mild steel in 1M HCl at different concentrations of nitrones ranging from 0.025‐1.0mM and at different temperatures ranging from 30‐70°C. Among these compounds NN gives the best performance even at higher temperatures. Potentiodynamic polarisation studies reveal the fact that all compounds behave as mixed type inhibitors. Hydrogen permeation studies reveal the fact that all the compounds bring down the permeation current. The absorption of these compounds on the mild steel surface from 1M HCl obeys Temkin’s absorption isotherm.

Electrochemical sorption of H into Fe and mild-steel: kinetic conditions for enhancement or inhibition by adsorbed HS-

Sulfide species, HS-, S2- and H2S, are often the most common and important poisons that arise in practical situations of embrittlement of ferruginous metals by sorbed H. The absorption and permeation of H can be either enhanced or inhibited under conditions of cathodic polarization in the presence of HS-. The effect of chemisorption of S on H transfer into and through Fe and mild-steel in aqueous NaOH solution has been studied comparatively in relation to poisoning by species derived from AsO2- using a kinetic equation-fitting procedure applied to H permeation currents in relation to simultaneously measured polarization behaviour on the H2-evolution side of a bielectrode membrane. A kinetic-fitting model is applied to all the constituent partial reactions involved at the electrode, including processes involving chemisorbed poison (P) species. The important relation of surface coverage by H to the H concentration in a sub-surface state is examined in relation to the kinetics of steps in the cathodic H2 evolution reaction (HER) and the step of interfacial transfer of H into the metal host. The rates of absorption and desorption of H, and its diffusion from the sub-surface layer into the bulk metal, are important in determining the effects of the poisons on the sub-surface concentration of H and therefore the H permeation current.

Evaluation of the Hydrogen Embrittlement Behaviour by Means of the Permeation Current Measure in Slow Strain Rate Conditions of a Micro-Alloyed Steel

The measure of the hydrogen permeation current through a metal membrane is a well-consolidated electrochemical technique to evaluate the effect of the environment, the polarisation and the type of steel related to hydrogen diffusion. Permeation tests allow to evaluate the stationary flow of hydrogen and the degree of surface coverage. In this work, permeation tests were carried out in a 35g/L NaCl solution at -1.05 V and -2 V vs. SCE on a pipeline micro-alloyed steel. The permeation current was measured on samples without load, with a constant load applied and in slow strain rate conditions. Afterwards, hydrogen permeation parameters were correlated to the results of Slow Strain Rate Tests (SSRT) in order to improve the knowledge on the hydrogen embrittlement mechanism of this type of steels.