Carbon Steel In Aqueous Solutions Research Articles

Synthesis and Characterization of Polypyrrole Film Doped with Both Molybdate and Salicylate and Its Application in the Corrosion Protection for Low Carbon Steel.

Polypyrrole (PPy) films doped with molybdate and salicylate have been successfully electropolymerized on low carbon steel in aqueous solutions containing both molybdate and salicylate in a one-step process that did not require any pre-treatment of the steel substrate. Salicylate-doped PPy films were synthesized in the same way for comparison. The steel surface was rapidly inhibited and the PPy-based films were formed on it easily. The PPy-based films were characterized by Fourier transform infrared, scanning electron microscopy, energy dispersive X-ray, and thermal gravimetric analysis methods. The corrosion protection performance of the coatings was investigated with electrochemical impedance spectroscopy, open circuit potential (OCP), salt spray test, and Tafel polarization. It was found that in the presence of both molybdate and salicylate as dopants, the films on steel could present a better corrosion resistance than PPy film doped with only salicylate. The self-healing property of PPy-based films was observed on the OCP measurement with the fluctuation of rest potential. The salt spray test results showed that the PPy film doped with both salicylate and molybdate was more salt-resistant than the PPy film doped with only salicylate. The results suggest that the PPy coatings doped with both molybdate and salicylate are potential for application as metallic anti-corrosion coatings.

Understanding the synergistic effect of CO2, H2S and fluid flow towards carbon steel corrosion

The synergistic effect of CO2, H2S and fluid flow towards carbon steel pipelines was studied by systematically evaluating the corrosion response of AISI 1020 carbon steel in aqueous solutions containing CO2 and CO2/H2S at various contents under the static and dynamic conditions at 60 °C. The results have revealed that the dissolved H2S can impede the formation of FeCO3 crystals by the preferential adsorption process of FeHSads+ to form the porous iron sulfide scale, through which the corrosive species, especially in dissolved CO2, can easily reach the steel/scale interface and accelerate the dissolution of steel matrix. On the other hand, the limited adsorption process of FeHSads+, enhanced mass transport of corrosive species/Fe2+ along with easy spalling of iron sulfide scale with poor adhesion are expected under the action of fluid flow, ultimately aggravating the localized and general corrosion of carbon steel.

Experimental and computational chemical studies on the corrosion inhibitive properties of carbonitrile compounds for carbon steel in aqueous solutions

The present work aims to study 6-amino-4-aryl-2-oxo-1-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile derivatives namely: 6-Amino-2-oxo-1,4-diphenyl-1,2-dihydropyridine-3,5-dicarbonitrile (PdC-H), 6-Amino-2-oxo-1-phenyl-4-(p-tolyl)-1,2-dihydropyridine-3,5-dicarbonitrile (PdC-Me) and 6-Amino-4-(4-hydroxyphenyl)-2-oxo-1-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile (PdC-OH) as corrosion inhibitors to provide protection for carbon steel in a molar hydrochloric acid medium. Chemical measurements such as (weight loss) and electrochemical techniques such as (Potentiodynamic polarization, electrochemical impedance spectroscopy, and Electron frequency modulation) were applied to characterize the inhibitory properties of the synthesized derivatives. The adsorption of these derivatives on the carbon steel surface was confirmed by Attenuated Total Refraction Infrared (ATR-IR), Atomic Force Microscope (AFM), and X-ray Photoelectron Spectroscopy (XPS). Our findings revealed that the tested derivatives have corrosion inhibition power, which increased significantly from 75.7 to 91.67% on the addition of KI (PdC-OH:KI = 1:1) to inhibited test solution with PdC-OH derivative at 25 °C. The adsorption process on the metal surface follows the Langmuir adsorption model. XPS analysis showed that the inhibitor layer consists of an iron oxide/hydroxide mixture in which the inhibitor molecules are incorporated. Computational chemical theories such as DFT calculations and Mont Carlo simulation have been performed to correlate the molecular properties of the investigated inhibitors with experimental efficiency. The theoretical speculation by Dmol3 corroborates with the results from the experimental findings.

Corrosion characteristics of carbon steel in solutions of synthetic detergents

Data of corrosion rate are obtained experimentally, values of braking coefficient, protection degree of steel 10 in 3 % aqueous solutions of detergents ML-52, MS-8 and Labomid-203 are calculated. It is found that when the composition of synthetic detergents diethylene tetraborate ammonium (DETA) composition (NH4)2B4O7·2C2H8N2·2H2O concentration of 0.5 % wt., the corrosion rate of carbon steel is significantly reduced, and the values of the braking coefficient and the protection degree increase and reach almost significant values. By removing the potentiodynamic polarization curves, it is shown that in the presence of DETA, the dissolution potentials of steel 10 are shifted to the positive side relative to the potential in the background solutions and the anode process is predominantly slowed down. Corrosion-fatigue tests indicate increase in the coefficient of cyclic strength reserve of carbon steel in aqueous solutions of synthetic detergents with the addition of DETA. The results allow us to recommend the compound diethylene tetraborate ammonium as effective anticorrosive additive to synthetic detergents used to clean parts from technological contaminants in the repair of process metallurgical plants machines.

Opto-electrochemical Instruments; Detection of Crevise Corrosion

Background: Two techniques of laser optical interferometry have been reviewed for detection of crevice corrosion of low carbon steel samples in aqueous solutions. The first technique used an optical corrosion-meter to detect localized corrosion such as crevice corrosion, of the low carbon steel samples in seawater. The concept of the optical corrosion-meter was based on incorporating holographic interferometry and the cyclic polarization test. The second technique used a modified electrochemical noise technique based on holographic interferometry to detect crevice corrosion of the low carbon steel samples in 1 M of sodium hydroxide (NaOH) solution. Objective: Emphasis on the significant role of the optical techniques of detecting crevice corrosion of carbon steel in aqueous solutions alongside to the DC methods. Method: The optical corrosion-meter and the modified electrochemical noise technique were used in the present investigation. Results: Observations of crevice corrosion of the carbon steel samples in seawater by the optical corrosion-meter were found to be in agreement with the cyclic polarization test. In addition, the modified electrochemical noise technique was found to be very useful for quantitatively distinguishing of localized corrosion, passivation, and uniform corrosion of the carbon steel samples in 1 M NaOH solution. Conclusions: The optical techniques of detecting crevice corrosion of carbon steel in aqueous solutions were found efficient opto-electrochemical instruments for substantiating results of those DC methods. Keywords: Electronic instruments, electrochemical properties, electromagnetic field, optical corrosion-meter, holographic interferometry, electrochemical noise technique, and opto-electrochemistry.

Corrosion behaviour of carbon steel in aqueous solution containing Galena concentrate

Carbon steel specimen was left in an aqueous solution containing galena concentrate for 15 days. Electrochemical Impedance Spectroscopy (EIS) method was conducted at 1st, 3rd, 5th, 7th, 9th, 11th, 13th and 15th days of immersion. Carbon steel was immersed in the lower solid region of 25 wt% and 75 wt% galena concentrate in solution. After 15 days of immersion, polarization resistance was measured using linear polarization resistance (LPR) technique. Analysis of impedance data from EIS method enables the determination of polarization resistance. The result showed that polarization resistance increases as a function of the solid percentage of galena concentrate and corrosion of carbon steel could be minimized.

RESEARCH OF FRUIT CONSERVES’ CORROSIVE AGGRESSIVENESS

Corrosion of metal canning containers is one of the obstacles in spreading its application for packing of food. Particularly aggressive to the metal container is fruit canned medium, containing organic acids.The basic material for the production of metal canning container is white tinplate. The main advantage of white tinplate is the tin compounds are harmless to human organism. For this reason, a white badge is used widely, usually used for production of canning containers, packaging beverages. Despite the fact that recently often used containers made of aluminum badge (foil), the basic material for manufacturing metal canning containers is steel white tinplate.Now applied for coating paints and varnishes do not provide anti-corrosion protection of inner surface of metal containers during storage. Preserving of canned fruit quality in metal containers is largely defined corrosion resistance of the containers. This is due to the fact that the metal transition to canned fruit in due courses of corrosion processes is lowering the nutritional value and deterioration taste of the product, and while allocation of hydrogen is accompanied by swelling and destruction of metal containers.We have investigated a number of anti-corrosion coatings based on Fe-Cr and Fe-Sn-Ti of their behavior in aggressive mediums canned fruit. For the purpose of modeling such mediums the solutions of most widespread organic acids were used. The research allowed conclude, that in surface solid solutions Fe-Sn-Ti increase the corrosion resistance of carbon steel in aqueous solutions of malic, citric and tartaric acids. This implies that the surface solid solutions’ formation can significantly improve corrosion resistance in aggressive canning mediums.

EFFECT OF CHANGE IN CONCENTRATION OF ETHYLENE GLYCOL AQUEOUS SOLUTION ON HEAT TRANSFER COEFFICIENT DURING QUENCHING PROCESS

Simulation of quenching process of steel is one of the method to plot temperature profile and to calculate HTC at surface of specimen Quenching of medium carbon steel in aqueous solution of ethylene glycol with different concentration of 0 % to 60% by mass was done using ANSYS 15.5 CFX workbench. Initial temperature of cylindrical specimen was assumed to be 1173K and for quenchant it was assumed to be 298K. Temperature plots for different concentrations and cooling curves at core and surface of the specimen was obtained. Result of cooling curves at different concentration shows that cooling rate for 0% concentration of ethylene glycol was greatest and it goes on decreasing as concentration of ethylene glycol solution increases. Temperature plots after 10 sec. were presented. Results of temperature plots shows that temperature difference between core and surface temperature of specimen is largest in case of 0% concentration of ethylene glycol solution by mass and it goes on decreases as concentration of ethylene glycol solution by mass increases. In this simulation variation in thermal properties of aqueous solution of ethylene glycol were considered and hence simulation was more accurate. Temperature plots obtained in this simulation will be useful in structural analysis of quenching process to find out residual stresses induced due to temperature gradient.

Enhanced corrosion inhibition behavior of carbon steel in aqueous solution by Phosphoserine-Zn2+ system

The corrosion inhibition effect of carbon steel in aqueous solution was using a synergistic mixture of an environmentally friendly inhibitor system phosphoserine (PS) and Zn2+ using gravimetric studies, potentiodynamic polarization, and electrochemical impedance studies. Potentiodynamic polarization studies showed that the inhibitor system is a mixed type inhibitor. Electrochemical impedance studies of the metal/solution interface indicated that the surface film is highly protective against the corrosion of carbon steel in the aqueous solution. X-ray photoelectron spectroscopic analysis of the protective film exhibited the presence of the elements viz., iron, phosphorus, nitrogen, oxygen, carbon, and zinc. The chemical shifts in the binding energies of these elements inferred that the surface film is composed of oxides/hydroxides of iron, Zn(OH)2, and [Fe(II)/(III)-Zn(II)-PS] complex. Further, the surface examination techniques viz., FTIR, SEM, and AFM studies confirm the formation of an adsorbed protective film on the carbon steel surface. Based on the results obtained, a suitable mechanism of corrosion inhibition is presented.

Development and protection evaluation of two new, advanced ceramic composite thermal spray coatings, Al2O3–40TiO2 and Cr3C2–20NiCr on carbon steel petroleum oil piping

Carbon steel is the most commonly used material in the petroleum industry owing to its high performance and relatively low cost compared with highly alloyed materials. The corrosion resistance of carbon steel in aqueous solutions is dependent on the surface layer created on carbon steel. This layer often consists of siderite (FeCO3) and cementite (Fe3C), but it is neither compact nor dense. To improve the carbon steel surface resistance against corrosion and wear, a compact and dense layer can be deposited onto the surface by thermal spray coating. In this research, Al2O3–40TiO2 and Cr3C2–20NiCr were deposited onto mechanical part surfaces by HVOF spray technique. The present study describes and compares the electrochemical behavior of carbon steel, Cr3C2–20NiCr and Al2O3–40TiO2 in 3.5% NaCl using open-circuit potential measurement (OCP) and electrochemical impedance microscopy (EIS) for 36 days. The tribological and mechanical properties are also investigated using a tribometer (pin-on-disc). The results indicate that these chemical composition coatings facilitated significant anti-corrosion and anti-wear improvement. However, the samples coated with Al2O3–40TiO2 exhibited the lowest corrosion rate. In terms of wear performance, both coated samples displayed similar behavior under different loads. Scanning electron microscopy (SEM) showed the distinctive microstructure of the HVOF-sprayed samples before and after corrosion and wear testing.

Effect of calcium carbonate on low carbon steel corrosion behavior in saline CO2 high pressure environments

The CaCO3 influence on the corrosion properties of low carbon steel in aqueous solutions saturated with CO2 and NaCl at 80°C and 15MPa was investigated over time with respect to morphology, thickness, structure, chemical composition and corrosion rate. The corrosion product formed in CaCO3-based solution was a calcium-enriched siderite and the scales were thinner and more porous than the ones formed in solutions without CaCO3. The CaCO3 reduced the corrosion rate, but the scales produced in the presence of this compound presented depassivation followed by formation of pits during electrochemical measurements effectuated on corroded samples.

The corrosion inhibition performance of pectin with propyl phosphonic acid and Zn2+ for corrosion control of carbon steel in aqueous solution

A protective film has been formed on the surface of carbon steel in neutral aqueous environment using a synergistic mixture of an ecofriendly inhibitor, viz. pectin, along with propyl phosphonic acid (PPA) and Zn2+ ions. The inhibitive effect of pectin, PPA, and Zn2+ ions has been investigated by gravimetric studies, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The investigations revealed that pectin acts as an excellent synergist in corrosion inhibition. Optimum concentrations of all three components of the ternary formulation have been established by gravimetric studies. EIS and potentiodynamic polarization techniques have been employed to determine the nature of the inhibition process of the selected compounds. EIS studies of the metal–solution interface indicated that the surface film is highly protective against the corrosion of carbon steel. The results of potentiodynamic polarization revealed that the formulations are of mixed type (anodic and cathodic). Further, to characterize the protective film formed on the iron substrate, Fourier-transform infrared spectroscopy, atomic force microscopy (AFM), scanning electron microscopy, and X-ray photoelectron spectroscopy analytical techniques were employed. Based on the results obtained, a suitable mechanism of corrosion inhibition is presented.

炭素鋼の水溶液腐食

大気環境および酸素欠乏環境における水溶液中における炭素鋼腐食について，中性溶液中の腐食皮膜生成を中心に述べた．酸素の存在する大気環境下の中性溶液中における腐食皮膜生成の臨界pH，腐食皮膜沈殿比のpH依存性，および皮膜成長の放物線速度則について述べた．酸素欠乏環境下の炭素鋼腐食はH2Oの酸化によって進行し，高温では腐食皮膜の溶解プロセスが支配的であるが，低温では腐食皮膜成長プロセスが支配し，腐食皮膜溶解プロセスは長時間後の定常溶解状態で重要となる．

Corrosion inhibition behavior of propyl phosphonic acid–Zn2+ system for carbon steel in aqueous solution

The effectiveness of propyl phosphonic acid (PPA) as a corrosion inhibitor in association with a bivalent cation like Zn2+ has been studied. An eco-friendly inhibitor in controlling corrosion of carbon steel in neutral aqueous medium in the absence and presence of Zn2+ has been evaluated by gravimetric method. Impedance studies of the metal/solution interface indicated that the surface film is highly protective against the corrosion of carbon steel in the aqueous environment. Potentiodynamic polarization studies showed that the inhibitor is a mixed inhibitor. X-ray photoelectron spectroscopic analysis (XPS) of the protective film exhibited the presence of the elements viz., iron, phosphorus, oxygen, carbon and zinc. The chemical shifts in the binding energies of these elements inferred that the surface film is composed of oxides/hydroxides of iron(III), Zn(OH)2 and [Fe(II)/(III)–Zn(II)–PPA] complex. Further, the surface analysis techniques viz., FT-IR, AFM and SEM studies confirm the formation of an adsorbed protective film on the carbon steel surface. Based on all these results, a plausible mechanism of corrosion inhibition is proposed.

Corrosion inhibition of carbon steel in aqueous solution of ammonium nitrate and urea

The effect of diethanolamine (DEA) and hexamethylenetetramine (HMTA) on the corrosion of carbon steel (CS) in concentrated aqueous solution of ammonium nitrate and urea (ANU) was studied by weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy. Both amines showed high inhibition efficiency >99% above a concentration of 0.5 wt% at 25 and 50 °C. The addition of 0.1–0.5 wt% sebacic acid to the tested solution containing amines did not enhance the inhibition efficiency. A positive synergistic effect was observed when 0.1–0.5 wt% of cinnamic acid was added to the ANU solution containing 0.3–1 wt% of amines. These results clearly demonstrate the potential of using CS for storage and transport of ANU solutions under ambient conditions.

Inhibition and Biocide Actions of Sodium Dodecyl Sulfate-Zn2+ System for the Corrosion of Carbon Steel in Chloride Solution

The inhibition efficiency of sodium dodecyl sulfate (SDS) in controlling corrosion of carbon steel in aqueous solution containing 120 ppm of Clin the presence and absence of Zn 2+ has been evaluated by weight loss method. The formulation consisting of 300 ppm of SDS and 75 ppm of Zn 2+ gives 93 % inhibition efficiency. A synergistic effect exists between SDS and Zn 2+ . As the immersion period increases, the inhibition efficiency of SDS-Zn 2+ decreases. Polarization study reveals that this formulation controls both the anodic and cathodic reactions. AC impedance spectra reveal that a protective film is formed on the metal surface.

Electrochemically induced self-assembly of alkanethiolate adlayers on carbon steel in aqueous solutions

The electrochemical behavior of carbon steel was studied in near neutral buffered aqueous solutions saturated with mercaptoundecanoic acid (MUA) and dodecanethiol (DT) by using electrochemical techniques combined with X-ray photoelectron spectroscopy (XPS). MUA and DT adsorb on the Fe surface by cathodization in the potential range corresponding to the hydrogen evolution reaction by forming thiolate bonds. The presence of the adsorbate layer in contact with an extremely low amount of thiols in the neutral solutions hinders the hydrogen evolution reaction and prevents the formation of the iron oxides in a wide potential range.

Corrosion Inhibition by Prussian Blue

The inhibition efficiency (IE) of K 3[Fe(CN) 6] in controlling corrosion of carbon steel in aqueous solution containing 60 ppm of Cl - in the presence and absence of Zn 2+ has been evaluated by weight loss method. The formulation consisting of 100 ppm K 3[Fe(CN) 6] and 50 ppm Zn 2+ offers 98% inhibition efficiency to carbon steel immersed in aqueous solution containing 60 ppm Cl - . A synergistic effect exists between K 3[Fe(CN) 6] and Zn 2+ . As immersion period increases, the inhibition efficiency of K 3[Fe(CN) 6]� Zn 2+ system decreases. Polarization study reveals that this formulation controls the cathodic reaction predominantly. AC impedance spectra reveal that a protective film is formed on the metal surface. FTIR spectra reveal that the protective film consists of Prussian blue and Zn(OH) 2. The film is found to be UV fluorescent.

Corrosion in Aqueous Solution of Two Alkanolamines with CO2 and H2S: N-Methyldiethanolamine + Diethanolamine at 393 K

In this work we have used an apparatus constructed in our laboratory to systematically study the corrosion rate on metals and evaluate specialty chemical products for preventing metal corrosion in industrial plants. We performed experimental studies on the effect of specific variables on corrosion rates over carbon steel, such as pressure, concentration of alkanolamines in aqueous solution, and amount of acid gases (CO2 and H2S). The technique utilized to evaluate the corrosion rate is the well-known weight loss method. With the experimental apparatus and method developed in this work we have determined the corrosion rate of AISI 1010 carbon steel in aqueous solutions of known concentration of N-methyldiethanolamine (MDEA) and diethanolamine (DEA), individually, with and without acid gases, and in different alkanolamine blends with total alkanolamine mass fraction in the range 15−60%, with mass ratios of MDEA/DEA of 3.5/1 and 2/1, with the addition of different amounts of H2S and CO2 at a pressure range of 276−5861 kPa (40−850 psig). Corrosion rates over carbon steel were determined in the liquid phase and also in some runs in both liquid and vapor phases, at 393.15 K. In the studied systems the corrosion rate decreases when the concentration of the alkanolamine increases. It was also possible to establish the effect of the amount of CO2 and H2S, in an individual way as well as in a mixture, on the corrosion rate of the carbon steel. The results show that corrosion rate of the alkanolamine solutions is not affected by CO2 in the range 0−0.35 mol; however, the presence of H2S drastically increases the corrosion rate as the amount of H2S increases.

Influence of passivity on the tribocorrosion of carbon steel in aqueous solutions

The degradation of DIN 34CrNiMo6 steel sliding against alumina was investigated in NaOH and in borate buffer solutions of pH 8.4 under electrochemically applied passive potentials. Small amounts of chromate or chloride were added to the borate solutions to vary the nature of the passive film. Film thickness and composition were characterised using surface analysis (Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS)). For comparison, tribocorrosion experiments were carried out at appropriate applied cathodic potentials, where no iron oxidation is thermodynamically possible, and therefore no passive film is formed. Results show the crucial role played by surface oxidation not only with respect to wear accelerated corrosion processes but also on surface mechanical phenomena. Depending on the nature of the solution, passive carbon steel exhibits either subsurface cracking or plastic flow accompanied by wear. In absence of passive film, wear is negligible and large plastic flow of the metal occurs, independent of the nature of the solution.