Acid Corrosion Of Steel Research Articles

Activation of Sulfuric Acid Corrosion of Stainless Steel by Thiocyanate

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Synthesis and inhibiting capacity of new fluorine-containing quaternary ammonium salts

New fluorine-containing quaternary ammonium salts exhibiting a high inhibiting capacity against hydrochloric acid corrosion of low-carbon steels were synthesized. The polarization resistance method was used to determine the uniform-corrosion rates of steel-3 and steel-35 in relation to the structure of fluorine-containing moieties of quaternary ammonium salts and their concentration.

Effect of temperature on the inhibition of the acid corrosion of steel by benzimidazole derivatives

The effect of 2-mercaptobenzimidazole (inh. I) and 2-mercapto-5-methylbenzimidazole (inh. II) on the corrosion of mild steel in 1M solutions of sulphuric acid has been investigated in relation to the concentration of the inhibitor as well as temperature by various monitoring corrosion techniques. The results obtained revealed that these compounds are good inhibitors. All the impedance diagrams gave semicircles for both inhibitors indicating that the corrosion of mild steel is controlled by a charge transfer process and the presence of either inhibitor does not alter the mechanism of the dissolution of mild steel. In general, both inhibitors efficiencies increased with increasing the inhibitors concentration at all temperatures used. On the other hand, inhibitors efficiencies were almost constant with increasing the temperature at concentrations 5 × 10−4 M, 1 × 10−3 M and 5 × 10−3 M. The best performance was noticed in case of (inh. II) especially at the concentration 5 × 10−3 M. Adsorption of both inhibitors was found to follow Langmuir, Flory-Huggins isotherms and kinetic-thermodynamic model. The binding constants “K” were calculated for both inhibitors. On increasing the temperature, the value of “K” increased in both cases indicative of stronger binding of the inhibitor molecule to the mild steel surface and hence higher inhibition efficiency at higher temperatures. The activation energy of the corrosion reaction decreases with increasing the concentration of (inh. I) or (inh. II). The adsorption of both inhibitors on the surface of mild steel is probably chemisorbed on the electrode surface. The thermodynamic parameters were calculated. Mass loss measurements revealed that both inhibitors exhibit maximum inhibition efficiency with increasing the concentration and temperature which confirm the data obtained from AC impedance. DC polarization data reveals that, both inhibitors does not alter the mechanism of anodic behaviour of mild steel and they behave as mixed type inhibitors. Again both inhibitors exhibit maximum inhibition efficiency with increasing the concentration and temperature which confirm the data obtained from AC impedance.

Inhibition of Acid Corrosion of Low Alloy Steel by a New Schiff-Base

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Corrosion inhibition of mild steel in HCl solution by Tinidazole

Corrosion inhibition of mild steel in HCl solution by Tinidazole Tinidazole, a pharmaceutical compound has been investigated with reference to the inhibition of mild steel acidic corrosion in 1 molar HCl by means of weight loss and electrochemical measurements. The outcomes attained at 30°C revealed that the Tinidazole had obtained 90% inhibition efficiency at 400 ppm concentration. These results explain that the inhibition process occurs by means of adsorption. The inhibitor molecules adsorb on the surface of the metal, following Langmuir's adsorption isotherm. Potentiodynamic polarization measurements established that Tinidazole is an inhibitor of a mixed type. An appropriate equivalent electric circuit for modeling and the analysis of impedance data to give a better explanation of the process of corrosion inhibition have been proposed.

1‐Methyl‐3‐pyridine‐2‐yl‐thiourea as inhibitor for acid corrosion of stainless steel

AbstractThe inhibiting effect of 1‐methyl‐3‐pyridine‐2‐yl‐thiourea (MPT) on the corrosion of stainless steel in 0.5 M H2SO4 solution was investigated using weight loss and potentiostatic polarization techniques. The percentage inhibition efficiencies and surface coverage degrees increased with increasing additive concentration. Potentiostatic polarization studies revealed that MPT is of the mixed‐type inhibitor in 0.5 M H2SO4 solution. The adsorption of this inhibitor is also found to obey the Langmuir adsorption isotherm. From the adsorption isotherm, value of the ΔGads for the adsorption process was calculated. From the corrosion rate obtained at 25–55 °C Ea, ΔHa and possible mechanism have been proposed. Scanning electron microscopy (SEM) was done from the surface of the exposed sample indicating uniform film on the surface.

Adsorption rate and protective effect of tributyl(cyclohexyl)ammonium chloride inhibitor on the acidic corrosion of steel

The inhibition of corrosion of a steel surface by an inhibitor, tributyl(cyclohexyl)ammonium chloride (TBCA), was investigated by gravimetric and electrochemical polarization measurements in various aqueous solutions of HCl and H2SO4 acids. It is known that the most extensive corrosive destruction proceeds during the initial stage of contact between the metallic surface and the aggressive surroundings. The change from H2SO4 to HCl considerably decreases the time for formation of an adsorption layer. The high adsorption of the surface-active cationic TBCA on the steel electrode surface can be explained by the specific adsorption of Cl− anions increasing the negative charge on the electrode surface. It was observed that the value of the polarizing current can be increased from time to time by addition of more TBCA inhibitor. This fact can be explained by the low stability of the film-forming layer on the steel. A similar decrease of the protective effect was also observed in HCl solution. The inhibitor provides at least a slowing of the corrosion process (τ = 21 min). It was found that an increase in H2SO4 concentration from 1.0 to 0.2 N did not change the protective action of the inhibitor and had rather high values (θ = 283 ma/h, ψ = 84%, and τ = 14 min at [I] = 3.5 × 10−4 mol/L). It was shown that the attraction constant has a negative value (A = −1.5 and Ka = 22.3) for the inhibitor, which relates to a high value for the adsorption ability of TBCA in HCl solution and therefore with the intermolecular repulsive force between adsorption molecules having similar charges. The protective action of TBCA increases with an increase in temperature, which is correlated with the chemical nature of its adsorption on the steel surface.

Electrochemical study on the effect of Schiff base and its cobalt complex on the acid corrosion of steel

The effect of the Schiff base N, N′-bis (salicylaldehyde)-1,3-diaminopropane (Salpr) and its corresponding cobalt complex on the corrosion behaviour of steel in 1 M sulphuric acid solution were studied by electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization techniques. Spectrophotometry measurements were employed to investigate the stability of the complex in acid media. The inhibitive effect of Salpr and its stable octahedral cobalt complex is argued to their adsorption over the steel surface. Theoretical fitting of different isotherms, Langmuir, Flory–Huggins and the kinetic–thermodynamic model were tested to clarify the nature of adsorption. The data revealed that there might be non-ideal behaviour in the adsorption processes of Co(Salpr) complex on the steel surface. The Co(Salpr) could displace more water molecules from the steel surface than the corresponding Salpr. The bulky Co(Salpr) molecule could cover more than one active site.

Enhanced corrosion resistance of carbon steel in normal sulfuric acid medium by some macrocyclic polyether compounds containing a 1,3,4-thiadiazole moiety: AC impedance and computational studies

We report here the use of macrocyclic polyether compounds containing a 1,3,4-thiadiazole moiety ( n-MCTH) in the corrosion inhibition of C38 carbon steel in 0.5 M H 2SO 4 acid medium. ▪ The aim of this work is devoted to study the inhibition characteristics of these compounds for acid corrosion of C38 steel using electrochemical impedance spectroscopy (EIS). Data obtained from EIS show a frequency distribution and therefore a modeling element with frequency dispersion behaviour, a constant phase element (CPE) has been used. The experimental results obtained revealed that these compounds inhibited the steel corrosion in acid solution and the protection efficiency increased with increasing inhibitors concentration. The difference in their inhibitive action can be explained on the basis of the number of oxygen atoms present in the polyether ring which contribute to the chemisorption strength through the donor acceptor bond between the non bonding electron pair and the vacant orbital of metal surface. Adsorption of n-MCTH was found to follow the Langmuir’s adsorption isotherm. The thermodynamic functions of adsorption process were calculated and the interpretation of the results is given. These results are complemented with quantum chemical study in order to provide an explanation of the differences between the probed inhibitors. Correlation between the inhibition efficiency and the structure of these compounds are presented.

N′, N′-dialkylhydrazides as inhibitors of acid corrosion of steel

The effect of N′,N′-dialkylhydrazides of aliphatic carboxylic acids of the general formula C4H9CH(C2H5)C(O)NHN(R)2 on the corrosion behavior of St.20 steel in 0.1 and 1 M HCl was studied by electrochemical and gravimetric methods.

High temperature naphthenic acid corrosion of steel in high TAN refining media

Purpose - This paper aims to study the corrosion behavior of carbon steel and stainless steel in white oil with naphthenic acid under high temperature. Design/methodology/approach - The weight-loss method and surface analysis were used to study the corrosion behavior of steel in white oil with naphthenic acid. Findings - Naphthenic acids corrosion rates were directly related to experimental temperature, immersion time and total acid number (TAN). The activation energy was calculated and the process kinetics could be represented by Arrhenius-type equation. The relationship between the isothermal line in liquid phase and that in vapor phase at different TAN values had a significant distinction with the change of temperature. Originality/value - The findings have important implications for assessing the corrosivity of crude oils with high TAN value from various resources.

Effect of pulegone and pulegone oxide on the corrosion of steel in 1 M HCl

The inhibitive action of pulegone and pulegone oxide toward acid corrosion of steel in molar hydrochloric acid was studied by weight loss measurements, potentiodynamic polarization, and impedance spectroscopy (EIS) methods. The pulegone is extracted starting from oil of Pennyroyal Mint (Mentha pulegium). The natural compound was found to delay the corrosion rate. The pulegone oxide is prepared by oxidation of pulegone. The inhibition efficiency was found to increase with the inhibitor content to attain 81 and 75% at 5 g dm−3 for pulegone and pulegone oxide. The increase in temperature leads to an increase in the inhibition efficiency of the natural compared.

Effect of Surface Nanocrystallization on the Acid Corrosion and Corrosion Inhibition of Low Carbon Steel

The corrosion behavior of a nanocrystalline (NC) low carbon steel (LCS) surface film deposited on a conventional polycrystalline (PC) LCS by magnetron sputtering was studied in 0.5 M H2SO4 solution using impedance and potentiodynamic polarization techniques. The corrosion inhibiting effect of a non toxic organic compound (methionine) and synergistic KI additives was also studied. Microstructure characterization by X-ray diffraction and atomic force microscopy revealed no phase changes due to nanoprocessing and the grain size of the NC surface layer was ~ 40 nm. Electrochemical results show that both the PC and NC surfaces underwent active corrosion with no transition to passivation in the potential range studied. Surface nanocrystallization however increased the corrosion susceptibility of low carbon steel more than two-fold, leading to a decrease in interfacial impedance and an increase in the kinetics of the anodic reaction. Methionine inhibited the corrosion of both specimens with comparable inhibition efficiencies. Iodide ions synergistically increased the inhibition efficiency of methionine on both specimens. This synergistic effect was more pronounced for the bulk steel and has been discussed vis-à-vis the more positive surface charge on bulk steel surface at the corrosion potential compared to the nanocrystalline surface.

Electrochemical study of the inhibition of corrosion of stainless steel by 1,2,3-benzotriazole in acidic media

The mechanism and efficiency of corrosion inhibition using 1,2,3-benzotriazole (BTAH) as the inhibitor on stainless steel corrosion in sulphuric acid medium were studied. Electrochemical impedance spectroscopy (EIS) as well as the potentiodynamic polarization was used for the quantification of inhibition efficiency and determination of the mechanism of interaction of the metal surface with the inhibitor molecule. Under the present experimental condition 1,2,3-benzotriazole was found to be an efficient inhibitor for the acid corrosion of austenitic stainless steel and the inhibition efficiency of up to 97% was obtained. In presence of inhibitor there is a diffusional contribution on the mechanism of the corrosion process was observed in impedance measurements at low frequency region. Effect of temperature on the mechanism and also on the efficiency of the corrosion inhibition process was studied using the Arrhenius approximation of the rate law. Polarization experiments were performed at different solution temperatures. Thermodynamic parameters for the corrosion process were obtained and interpreted. The adsorption of the inhibitor, BTAH, on the stainless steel surface in the acid medium (0.1 M H 2SO 4) obeyed the Langmuir adsorption isotherm. Present results were discussed and compared with the similar results reported by some other groups.

Inhibition of acid corrosion of carbon steel using aqueous extract of olive leaves

The inhibitive action of the aqueous extract of olive ( Olea europaea L.) leaves toward the corrosion of C-steel in 2 M HCl solution was investigated using weight loss measurements, Tafel polarization, and cyclic voltammetry. It was found that the extract acts as a good corrosion inhibitor for the tested system. The inhibition efficiency increases with increasing extract concentration. The inhibitive action of the extract is discussed with a view to adsorption of its components onto the steel surface, making a barrier to mass and charge transfer. The adsorption of extract components onto the steel surface was found to be a spontaneous process and to follow the Langmuir adsorption isotherm. It was found also that such adsorption increases the activation energy of the corrosion process. The results of cyclic voltammetry showed that the presence of olive extract decreases the charge density in the transpassive region. The inhibition efficiency is greatly reduced as the temperature is increased.

Effects of arylthio-and arylseleno(methoxy)methanes on acid corrosion of CT3 steel

The effects of various arylthio-and arylseleno(methoxy)methanes on corrosion of CT3 steel in sulfuric and hydrochloric acid solutions were studied by gravimetric and voltammetric methods. Some compounds of theses classes were found to be effective inhibitors of the acid corrosion of CT3 steel. The presence of the-X-CH2-O-CH3 groups (X = S or Se) in aromatic amines and their derivatives enhanced their inhibitive properties. However, because these groups are highly hydrophobic, the molecules of inhibitors should contain other fragments that ensure sufficient solubility.

Polyfunctional effects of [1,3]thiazino[3,2-a]benzoimidazol-4-ones on steel corrosion

[1,3]Thiazino[3,2-a]benzoimidazol-4-ones were found to be effective inhibitors of the acid corrosion of steel 20 in 1 M HCl and 1 M H2SO4(pH 0) and valuable polyfunctional additives that enhance the anticorrosion properties and stimulate the formation of an epoxy powder coating.

1-Phenacylmethyl-2-(acylaminothiocarbonylamino)pyridinium bromides as protectors of steel acid corrosion

Inhibiting effect of 1-phenacylmethylpyridinium bromides containing acylthiourea substituents in the pyridine ring on corrosion of mild steel in sulfuric acid (3 M) was studied.

The inhibitive effect of hexamethylenetetramine on the acid corrosion of steel

The efficiency of hexamethylenetetramine (HMTA), as corrosion inhibitors for steel in de-aerated 0.3 M HCl, 0.1 M H 2SO 4 and 0.1 M H 2SO 4 + 1.0 × 10 −3 M HCl solutions have been determined by electrochemical studies. It was found that the HMTA acts a good corrosion inhibitor for steel corrosion in acids solutions. Increase in inhibition efficiency with the increase of concentrations of HMTA shows that inhibition actions are due to adsorption on the steel surface and adsorption follows the Langmuir isotherm. From the adsorption isotherms values of equilibrium constant ( K ads), values of free energies of adsorption ( Δ G ads ° ), were calculated. The effect of temperature on the corrosion behaviour in the presence of 1.0 × 10 −1 M inhibitors was studied in the temperature range of 293–323 K. The inhibition efficiency of HMTA increased with increasing temperature up to 323 K. Activation energies ( E a * ) were calculated from the obtained corrosion rates at different temperatures. Results obtained from both potentiodynamic polarisation and AC impedance measurements reveal that the compound is an effective inhibitor for the corrosion of steel and behave better in HCl than in H 2SO 4. Surface analyses were also carried out to establish the mechanism of corrosion inhibition of steel in acidic media.

The synergistic inhibitive effect and the thermodynamic parameters of 2 (2- hydroxylstyryl) pyridinium-N- ethyl iodide and some metal cations on the acid corrosion of low-carbon steel

The synergistic inhibitive effect and the thermodynamic parameters of 2 (2- hydroxylstyryl) pyridinium-N- ethyl iodide and some metal cations on the acid corrosion of low-carbon steel