Corrosion inhibition of carbon steel using novel N-(2-(2-mercaptoacetoxy)ethyl)-N,N-dimethyl dodecan-1-aminium bromide during acid pickling

A novel cationic surfactant, N-(2-(2-mercaptoacetoxy)ethyl)-N,N-dimethyl dodecan-1-aminium bromide, has been synthesized to study its corrosion inhibiting effect against carbon steel in 1.0 M HCl solution. The corrosion inhibition efficiency was measured by using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and weight loss methods. The inhibition efficiencies obtained from these methods were in good agreement. The inhibition efficiency slightly decreased in the temperature range 30–60 °C. The synthesized inhibitor acted as a mixed inhibitor. Thermodynamic adsorption and activation parameters were discussed. Adsorption of the synthesized inhibitor was found to follow the Langmuir adsorption isotherm. A chemical adsorption mechanism is proposed.     

Electrochemical and quantum chemical studies of some azomethine compounds as corrosion inhibitors for mild steel in 1 M hydrochloric acid

The corrosion inhibition effect of new azomethine compounds: PhNNC (COCH₃)NC₆H₄Y {Y = OCH₃ (SB₁), CH₃ (SB₂), H (SB₃), Br (SB₄) and Y = Cl (SB₅)} on mild steel in 1 M HCl, was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and quantum chemistry analysis. It has been found that the inhibition efficiency increased with increasing inhibitor concentration. The polarization curves showed that these Schiff bases function as mixed inhibitors. The adsorption of studied compounds on mild steel surface was found to follow the Langmuir isotherm. Molecular modeling was used to correlate corrosion inhibition properties and calculated quantum chemical parameters.     

Preparation of Fe2B boride coating on low-carbon steel surfaces and its evaluation of hardness and corrosion resistance

Fe₂B coating was prepared on low-carbon steel by surface alloying. A series of experiments were carried out to examine some surface properties of boride coating. The surface heat treatment of coated low-carbon steel was performed at 700 °C, 800 °C and 900 °C for 2 h, 4 h, 6 h and 8 h under hydrogen atmosphere. The boride coating was revealed by XRD analysis and the microstructure of the boride coating was analyzed by scanning electron microscopy (SEM). Depending on the temperature and time of the process, the hardness of the borided low-carbon steel ranged from 99 to 1100 HV. The hardness showed a maximum (about 1100 HV) at 900 °C for 8 h. The corrosion resistance of the borided samples was evaluated by the Tafel polarization and electrochemical impedance spectroscopy (EIS). Shift in the corrosion potential (E_corr) towards the noble direction was observed, together with decrease in the corrosion current density (I_corr), increase in the charge transfer resistance (R_ct) and decrease in the capacitance (C_c), which indicated an improvement in corrosion resistance with increasing temperature and time of the treatment.     

Adsorption and inhibition effect of Ascorbyl palmitate on corrosion of carbon steel in ethanol blended gasoline containing water as a contaminant

The adsorption and inhibition effect of Ascorbyl palmitate (AP) on carbon steel in ethanol blended gasoline containing water as a contaminant (GE10 + 1%water) was studied by weight loss and electrochemical impedance spectroscopic (EIS) techniques. The results showed that the addition of ethanol and water to gasoline increase the corrosion rate of carbon steel. AP inhibits the corrosion of carbon steel in (GE10 + 1% water) solution to a remarkable extent. The adsorption of AP on the carbon steel surface was found to obey the Langmuir adsorption isotherm model. The values of activation energy (E_a) and various thermodynamic parameters were calculated and discussed.     

Correlation between the corrosion resistance and the semiconducting properties of the oxide film formed on AZ91D alloy after solution treatment

The corrosion resistance and semiconducting properties of the oxide film formed on the AZ91D alloy were evaluated. The alloy was tested in the as-cast condition and after a solution annealing treatment. Electrochemical impedance spectroscopy measurements and potentiodynamic polarization curves were obtained in a H₃BO₃ (0.05 M) + Na₂B₄O₇⋅10H₂O (0.075 M) solution with pH = 9.2 at room temperature. The semiconducting properties of the oxide film were evaluated using Mott–Schottky plots. The corrosion resistance of the AZ91D was reduced after the solution treatment while the semiconducting properties of the passive films were little affected.     

Corrosion behaviour of Al–29at%Co alloy in aqueous NaCl

Microstructure and corrosion behaviour of a binary Al–29 at%Co alloy have been studied. The alloy was prepared by arc-melting of Al and Co in high purity Ar and rapidly solidified on a water-cooled Cu mould. The alloy chemical composition and microstructure were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. Furthermore, the corrosion behaviour was studied by potentiodynamic polarization in aqueous NaCl (0.6 mol dm⁻³) at room temperature. The alloy was found to consist of three phases: hexagonal Al₅Co₂, Z-phase and AlCo (β). The corrosion resistance of different intermetallic phases is characterized. The results are compared to previously published results of Al–TM (TM = transition metal) alloys.     

Inhibition by Ginkgo leaves extract of the corrosion of steel in HCl and H2SO4 solutions

The inhibition effect of Ginkgo leaves extract (GLE) on the corrosion of cold rolled steel (CRS) in 1.0–5.0 M HCl and 0.5–2.5 M H₂SO₄ solutions was investigated for the first time by weight loss, potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) methods. The results show that GLE is a good inhibitor, and exhibits more efficient in 1.0 M HCl than 0.5 M H₂SO₄. The adsorption of GLE on CRS surface obeys Langmuir adsorption isotherm. GLE acts as a mixed-type inhibitor in 1.0 M HCl, while a cathodic inhibitor in 0.5 M H₂SO₄.     

Investigation of corrosion inhibition effect of 3-[(2-hydroxy-benzylidene)-amino]-2-thioxo-thiazolidin-4-one on corrosion of mild steel in the acidic medium

The corrosion behavior of mild steel (MS) in 0.5 M H₂SO₄ was studied using 3-[(2-hydroxy-benzylidene)-amino]-2-thioxo-thiazolidin-4-one (HBTT) as inhibitor using the conventional potentiodynamic polarization studies, linear polarization studies (LPR), electrochemical impedance spectroscopy studies (EIS). SEM was utilized for surface characterization. The results showed that HBTT posses excellent inhibition effect towards MS corrosion. The inhibitor molecules were first adsorbed on the MS surface and blocking the reaction sites available for acid attack. Adsorption of inhibitor was found to obey Langmuir isotherm and was more chemical than physical.     

Experimental and theoretical evaluation of semicarbazones and thiosemicarbazones as organic corrosion inhibitors

The inhibition ability of four thiosemicarbazones (1A–D) and two semicarbazones (2A–B) towards carbon steel corrosion in 1.0 M HCl was evaluated by molecular modeling, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) at different inhibitor concentrations. Polarization curves showed that all of the evaluated compounds acted as mixed inhibitors. EIS plots indicated that the presence of the inhibitors increases the charge transfer resistance of the corrosion process, increasing the inhibition efficiency. The adsorption of the evaluated inhibitors obeys the Langmuir adsorption isotherm. The theoretical results were corroborated by experimental data, with both the experimental and theoretical data showing that the thiosemicarbazones are better corrosion inhibitors than the semicarbazones.     

Effect of electrolyte and monomer concentration on anticorrosive properties of poly(N-methylaniline) and poly(N-ethylaniline) coated mild steel

The electrosynthesis of poly(N-methylaniline) (PNMA) and poly(N-ethylaniline) (PNEA) coatings on mild steel in aqueous oxalic acid solutions was carried out by potentiodynamic synthesis technique. The effects of monomer and electrolyte concentrations on electrochemical growth of PNMA and PNEA coatings on mild steel substrates were investigated. Repassivation peak did not appear during electrosynthesis of PNMA and PNEA coatings from solutions containing 0.1 M monomer and 0.1 M electrolyte. The tests for corrosion protection of the polymer coated and uncoated mild steel substrates were done in 3% NaCl solutions by dc polarization and electrochemical impedance spectroscopy (EIS) techniques. Corrosion tests revealed that PNMA and PNEA coatings exhibited effective anti-corrosive properties. The acidity of the polymerization solution was found to influence the anticorrosive behavior of the polymer coating.     

Corrosion of a stainless steel and nickel-based alloys in high temperature supercritical carbon dioxide environment

Corrosion of four alloys has been studied in supercritical carbon dioxide at 650 °C and 20 MPa, specifically AL-6XN stainless steel and three nickel-based alloys, PE-16, Haynes 230, and Alloy 625. The tests were performed for exposure durations of up to 3000 h with samples being removed for analyses at 500 h intervals. The corrosion performance of the alloys was evaluated by weight change measurements, and the surface oxide layers were characterized by scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Weight gain measurements showed that the Al-6XN stainless steel exhibited the least corrosion resistance while the weight gains were nearly similar for the other alloys. The oxide layer in AL-6XN stainless steel was composed of large equiaxed grained outer layer of Fe₃O₄ (magnetite) and an inner layer of FeCr₂O₄. Oxide spallation was observed in this stainless steel even after 500 h exposure. In all alloys, Cr-rich oxides phases of Cr₂O₃ and Cr_1.4Fe_0.7O₃ were identified as the protective layers. In alloy PE-16 a thin layer of aluminum oxide formed that promoted the corrosion resistance of the alloy. Cr₂O₃ was identified as the main protective oxide layer in nickel base alloys Haynes 230 and 625.     

Determination of the corrosivity of Pb-containing salt mixtures

The composition of deposits from waste firing boilers is dominated by calcium-, alkali-chlorides and sulfates. Additionally, significant quantities of heavy metals such as Zn and Pb are usually present during waste combustion. In this high temperature corrosion study, two boiler materials, a low alloy ferritic steel (10CrMo9-10) and an austenitic stainless steel (AISI 347), were exposed to PbCl₂–ZnCl₂–KCl, PbCl₂–KCl and PbCl₂–K₂SO₄ salt mixtures as well as to the single salts of PbCl₂, K₂SO₄ and KCl. In the tests, the salt or the salt mixture was put on a pre-oxidized and cleaned steel sample and then heat treated at 400, 500 and 600 °C for 168 h (1 week) in a horizontal tube furnace. After the test, the metallographic cross-sections of the specimens were characterized with a SEM/EDX analyzer and the thickness of the corrosion layer was determined for each sample. The corrosion layer thickness measurements showed severe corrosion on 10CrMo9-10 already at 400 °C when 5 wt.% PbCl₂ was mixed with KCl or K₂SO₄ With all the PbCl₂ containing salt mixtures at temperatures around and above 500 °C a significant corrosion was observed on both materials. In order to estimate the relative corrosivity of PbCl₂ containing salt mixtures, the results from the laboratory experiments in this work were compared to an earlier study done with a corresponding ZnCl₂ containing salt mixture.     

Pitting corrosion of intermetallic compound Ni3(Si,Ti) with 2 at% Mo in sodium chloride solutions

The pitting corrosion of Ni₃(Si,Ti) with 2 at% Mo consisting of a single intermetallic compound Ni₃(Si,Ti) phase of L1₂ structure and a two phase mixture of L1₂ and fcc nickel solid solution was investigated as functions of test temperature and chloride concentration in sodium chloride solutions by using a potential step method and compared with that of intermetallic compound, Ni₃(Si,Ti). The pitting potential obtained for the Ni₃(Si,Ti) with 2 at% Mo decreased with increasing chloride concentration and test temperature. A critical chloride concentration below which no pitting corrosion took place was found to exist and to decrease with increasing test temperature. The specific pitting potential at the critical chloride concentration also decreased with increasing test temperature. The pitting potential of Ni₃(Si,Ti) with 2 at% Mo was higher than pure nickel, but lower than that of Ni₃(Si,Ti). A critical chloride concentration was found to be lower than that of Ni₃(Si,Ti), whereas the specific pitting potentials at the critical chloride concentration was found to be higher than that of Ni₃(Si,Ti). Pitting corrosion occurred in the two phase mixture region.     

An investigation of three novel nonionic surfactants as corrosion inhibitor for carbon steel in 0.5 M H2SO4

The inhibition effect of three novel nonionic surfactants, 2-((alkylimino)methyl)phenyl bis(53-hydroxy-3,6,9,12,15,18,21,24,27,30,33,36,39,42,45,48,51-heptadecaoxatripentacontyl) phosphate (I–III), on the corrosion of carbon steel in 0.5 M H₂SO₄ was studied by polarization, EIS and weight loss measurements. It was found that all the inhibitors were effective inhibitors and their inhibition efficiency was significantly increased with increasing both concentration and temperature. Polarization curves revealed that the used inhibitors represent mixed-type inhibitors. Adsorption of used inhibitors led to a reduction in the double layer capacitance and an increase in the charge transfer resistance. Adsorption of used compounds was found to obey Langmuir isotherm and showed a chemical mechanism.     

Allyl thiourea as a corrosion inhibitor for cold rolled steel in H3PO4 solution

The inhibition effect of allyl thiourea (ATU) on the corrosion of cold rolled steel (CRS) in 1.0 M H₃PO₄ solution at 20–50 °C was studied by weight loss, potentiodynamic polarisation, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) methods. The results show that ATU is a good inhibitor, and the maximum inhibition efficiency of 0.5 mM inhibitor is higher than 95% at all studied temperatures. The adsorption of ATU obeys Langmuir adsorption isotherm. Polarisation curves show that ATU behaves as a mixed-type inhibitor. EIS spectra exhibit one capacitive loop. The inhibition action is also evidenced by SEM.     

Corrosion synthesis of boron carbide with pore and hollow structure

In this study, corrosion synthesis of boron carbide particles with pore size ranging from hundreds of nanometers to several micrometers was reported. Firstly, the pristine boron carbide powders which contain free carbon have been synthesized at 350 °C in a steel autoclave. As the pristine boron carbide was refluxed by HClO₄ at 170 °C for 1–2 h, the boron carbide particles with macropores were produced. Similarly, the boron carbide nanocages can also be obtained. The corrosion of the embedded amorphous and/or low crystallinity carbon/boron carbide using HClO₄ was considered for the formation of boron carbide with macropores and hollow nanocages.     

Long-term monitoring of atmospheric corrosion at weathering steel bridges by an electrochemical impedance method

Weathering steel corrosion was monitored for one to two years under natural atmosphere by an electrochemical impedance technique. Two identical comb-shape weathering steel sheets embedded in epoxy resin were used as monitoring probe electrodes at two different bridges in Japan. Impedances at 10 kHz (Z_10kHz) and 10 mHz (Z_10mHz) were automatically measured every hour. Coupons (50 × 50 × 2 mm³) prepared from the same steel sheets were exposed together to measure the corrosion mass loss. The average (Z_10mHz)⁻¹ value for half to one year exposure correlated well with the average corrosion rate determined from the corrosion mass loss.     

Corrosion behavior of an alumina forming austenitic steel exposed to supercritical carbon dioxide

Microstructure characterization of corrosion behavior of an alumina forming austenitic (AFA) steel exposed to supercritical carbon dioxide was conducted at 450–650 °C and 20 MPa. At low temperature and short exposure times, the oxidation kinetics were parabolic and the oxide scales were mainly composed of protective and continuous Al₂O₃ and (Cr, Mn)-rich oxide layers. As the temperature and exposure time increased, the AFA steel gradually suffered breakaway oxidation and its oxide scales showed a multilayer structure mainly composed of Fe₃O₄, (Cr, Fe)₃O₄, NiFe/FeCr₂O₄/Cr₂O₃/Al₂O₃, FeCr₂O₄/Al₂O₃, and NiFe/Cr₂O₃/Al₂O₃, in sequence. The corrosion mechanism based on the microstructure evolution is discussed in detail.     

Corrosion behavior of low-alloy steel containing 1% chromium in CO2 environments

Corrosion behavior of low-alloy steel containing 1% Cr (1Cr) with normalized (ferritic–pearlitic) and quenched-and-tempered (tempered martensitic) microstructures was investigated in CO₂ environments at 60 °C. The severe localized corrosion which was observed in N80 carbon steel, did not exist for 1Cr steel due to the formation of a compact and self-repairable Cr-rich scale. For 1Cr steel, the corrosion resistance with ferritic–pearlitic microstructure was better than that with tempered martensitic microstructure. An apparent corrosion scale spallation was observed on the surface of quenched-and-tempered 1Cr steel, while only slight scale spallation was seen for normalized 1Cr steel.     

樟树叶提取液在硫酸介质中对碳钢的缓蚀作用

应用动电位极化法和电化学阻抗(EIS)研究了樟树叶提取液(CCLE)在硫酸介质中对碳钢的缓蚀性能和缓蚀机理. 结果表明, 采用酸浸泡法从樟树叶中提取的缓蚀剂, 对碳钢在10% H₂SO₄溶液中具有良好的缓蚀作用, 随着提取液浓度的增加, 缓蚀效率增大; 随着实验温度升高, 缓蚀效率减小. 樟树叶提取液为混合抑制型缓蚀剂, 提取液中的有效缓蚀成分在碳钢表面的吸附满足Langmuir等温吸附方程; 樟树叶提取液的加入使碳钢在硫酸中反应的表观活化能增加, 起到缓蚀作用.