Mössbauer spectroscopy study on the corrosion inhibition of carbon steel in hydrochloric acid solution

The effect of ammonium polymolybdate (APM) on the corrosion of carbon steel in a solution of 1 M HCl was studied by weight loss and Mössbauer spectrometry. Inhibition efficiencies (P) have been obtained from weight measurement. The inhibition efficiencies increased with increase APM concentration. Mössbauer spectrometry shows that a superficial compound is formed on the electrode surface as a result of corrosion.     

Oxidation behavior of ferritic/martensitic steels in flowing supercritical water

The oxidation behavior of two Ferritic/Martensitic(F/M)steels including novel SIMP steel and commercial P91 steel were investigated by exposure to flowing deaerated supercritical water(SCW)at 700℃for up to 1000 h.The kinetic weight gain curves follow parabolic and near-cubic rate equations for SIMP and P91 steels,respectively.X-Ray Diffraction analysis showed the presence of magnetite and a spinel phase in flowing SCW for both steels.The morphology and structure of the oxide scales formed on these two steels were analyzed.The relationship between the microstructure and oxidation behavior and the reason that SIMP steel showed better oxidation resistance than P91 steel were discussed.     

The electrochemical behavior of niobium low-pressure-plasma-sprayed coatings in hydrochloric acid

Niobium coatings vacuum plasma sprayed under an inert atmosphere onto steel substrates are shown to be dense and free from visible oxide. Electrochemical analysis in deaerated 0.5 M and 4 M hydrochloric acid solutions indicated that vacuum plasma-sprayed niobium coatings are highly resistant to both general and local corrosion. Cyclic voltammetry in deaerated 4 M hydrochloric acid showed no breakdown during the anodic potentiodynamic sweep, behavior similar to that observed for pure niobium foil. The feasibility of applying low-pressure-plasma-sprayed niobium coatings for the protection of steel substrates in highly aggressive hydrochloric acid solutions was established.     

Corrosion inhibition of aluminum by novel phthalocyanines in hydrochloric acid solution

The corrosion inhibition characteristics of quaternized 1,(4)-tetrakis[(2-mercapto)pyridine]phthalocyanine (I) and 2,3-octakis[(2-mercapto)pyridine] phthalocyanine (II) on aluminum in 0.1 M HCl solution has been studied by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The maximum inhibition efficiency was obtained for compound I with two-electrochemical techniques applied. Langmuir isotherm fits well the experimental data. The inhibition efficiency increases with increase in the phthalocyanine concentration, but decreases with an increase in temperature. The phthalocyanines act predominately as cathodic inhibitor.     

Corrosion inhibition of iron by amphoteric surfactants in hydrochloric acid solutions

In the present work the corrosion inhibition of iron in 2 M HCl solution by amphoteric surfactants was studied. The techniques of measurements were (i) weight loss, (ii) linear polarization and (iii) electrochemical impedance spectroscopy. The investigated surfactants have the structure: Fig. a

---

where, R = –C₁₄H₂₉(I), –C₁₅H₃₁(II), –C₁₆H₃₃(III), –C₁₇H₃₅(IV), –C₁₈H₃₇(V). These surfactants have a high inhibitory effect on the corrosion of iron in HCl solution. The inhibiting effect of these surfactants may take place through the blocking effect resulting from their adsorption on the metallic surface and hydrophobic effect. The inhibition efficiency increases according to the order: I < II < III < IV < V. This is due to the increase of the length of the alkyl group (–R) in the surfactants. The adsorption of these surfactants via their adsorption centers on the metallic surface obeyed the Frumkin adsorption isotherm. The presence of these surfactants in the corrosive solution increases the activation energy of the corrosion process with that order of inhibition efficiency.     

Corrosion behaviour of copper-reinforced carbon electrodes in dilute hydrochloric acid solutions

The corrosion behaviour of experimentally prepared copper-reinforced carbon electrodes in dilute hydrochloric acid is investigated. The electrodes are not only directly attacked by the acid, but they are also subjected to galvanic corrosion. The baking temperature and time are the most crucial processing variables. A minimum in the corrosion rate is always achieved when the electrodes are baked at 400 °C for 1.5 h, the level depending on the copper content. The corrosion resistance increases progressively with the baking temperature as long as the baking time is less than 1.5 h. Baking for more than 1.5 h results in increasing corrosion rate. The presence of copper increases the corrosion resistance of the prepared electrodes.     

盐酸浓度对TiO2纳米棒的影响

采用水热合成方法在透明导电玻璃上制备了TiO2纳米棒阵列,利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)等手段对样品进行分析和表征。研究了盐酸浓度对阵列形貌和结构的影响,并针对其影响机理做了进一步的探讨。结果表明,TiO2纳米棒为金红石相,在盐酸与去离子水的比例为1.0时,TiO2纳米棒阵列生长方向垂直于衬底,排列整齐,组织均匀致密。     

Effects of tempering on internal friction of carbon steels

Two steels containing 0.626 and 0.71 wt.% carbon have been studied to determine the effects of tempering on the microstructure and the internal friction. The steels were annealed at 1093 K, quenched into water and tempered for 60 min at 423 K, 573 K and 723 K. The increase of the tempering time diminishes the martensite tetragonality due to the redistribution of carbon atoms from octahedrical interstitial sites to dislocations. Internal friction spectrum is decomposed into five peaks and an exponential background, which are attributed to the carbide precipitation and the dislocation relaxation process. Simultaneous presence of peaks P1 and P2 indicates the interaction of dislocations with the segregated carbon and carbide precipitate.     

Corrosion inhibition of aluminum in hydrochloric acid solution by alkylimidazolium ionic liquids

The effects of newly synthesized three alkylimidazolium ionic liquids—1-butyl-3-methylimidazolium chlorides (BMIC), 1-hexyl-3-methylimidazolium chlorides (HMIC) and 1-octyl-3-methylimidazolium chlorides (OMIC)—on the corrosion of aluminum in 1.0 M HCl were investigated using potentiodynamic polarization, electrochemical impedance spectroscopy and weight loss methods. All measurements showed that the inhibition efficiency increased with increase in the concentration of inhibitor and the effectiveness of these inhibitors was in the order of OMIC > HMIC > BMIC. Polarization curves revealed that the studied inhibitors were mixed type inhibitors. The adsorption of the inhibitors on the aluminum surface obeyed Langmuir adsorption isotherm and had a physical mechanism. The effect of temperature on the corrosion behavior in the presence of 5 × 10^?3 M of inhibitors was studied in the temperature range of 303–333 K. The associated activation energy of corrosion and other thermodynamic parameters such as enthalpy of activation (ΔH), entropy of activation (ΔS), adsorption equilibrium constant (K_ads) and free energy of adsorption (ΔG_ads) were calculated to elaborate the mechanism of corrosion inhibition.     

Effects of alcohol-based inhibitors on corrosion of mild steel in hydrochloric acid

The inhibition efficiencies of Octyl alcohol (OCAL) and propargyl alcohol (PRAL) on the corrosion of mild steel in 15% commercial hydrochloric acid have been evaluated by mass loss method, electrochemical techniques and surface analysis techniques with 0–1% inhibitor concentration at 30 °C and 105 °C. Both OCAL and PRAL are excellent inhibitors for the above-mentioned system. OCAL gives 87% and 82% inhibition efficiencies at 30 °C and 105 °C, respectively, for 1% inhibitor concentration whereas PRAL gives 100% and 99% efficiencies at 30 °C and 105 °C, respectively, for 0.6% inhibitor concentration. Polarization studies confirm that OCAL and PRAL are mixed type inhibitors. OCAL and PRAL obey Temkin's adsorption isotherm at both the temperatures. UV-reflectance, FT-IR and SEM studies confirm that the surface of mild steel is not affected at the maximum concentration of OCAL and PRAL.     

Corrosion inhibition of mild steel in hydrochloric acid solution by methylene blue dye

The corrosion inhibition of mild steel in hydrochloric acid solution by methylene blue dye (MB) was investigated by gravimetric techniques at 30 and 60 °C as well as thermometric technique. MB was shown to be an inhibitor in the acidic corrodent. Inhibition efficiency increased with MB concentration but decreased with rise in temperature, with maximum value of 94–95% obtained for 5.0 mM MB at 30 °C. Corrosion inhibition is attributed to the adsorption of MB on the mild steel surface via a physical adsorption mechanism. These results were further corroborated by kinetic and activation parameters for corrosion and adsorption processes evaluated from experimental data.     

Evaluation of the inhibition behavior of carbon dots on carbon steel in HCl and NaCl solutions

An eco-friendly and effective corrosion inhibitor(N-CDs) was acquired by hydrothermal method in methacrylic acid and ethyl(methyl)amine precursors. Afterwards, the weight loss and electrochemistry measurement were chosen to appraise the corrosion inhibition behavior of as-prepared N-CDs for Q235 steel in Cl-contained solutions. The change rules of EIS and Tafel data displayed that the as-prepared N-CDs revealed a high-efficiency protection for steel in all test environments. Meanwhile, the inhibition efficiency of steel reached up to 93.93%(1 M HCl) and 88.96%(3.5 wt% Na Cl) at 200 mg/L of N-CDs.Furthermore, the N-CDs could form the adsorption film on steel surface to avoid the strong attack of Cl-. By analysis, the adsorption mechanism of as-prepared N-CDs on steel surface was physicochemical interaction, which strictly complied with the Langmuir adsorption model in both solutions.     

Mechanical fatigue behavior of chromium and nickel plain carbon steels

The influence of chemical composition on fatigue behavior and fatigue crack growth rates is variegated. Thus, chromium and nickel affect the fatigue limit but have no influence on the mean values of crack growth rates described by the Paris equations. The effect of carbon on the fatigue limit and the propagation of fatigue cracks is utterly different: It affects the exponentm on the right-hand side of the Paris equation, and the higher the content of carbon, the more pronounced its effect. Carbon also affects the dependencesm=f(Tr),m=f(HB),m=f(R), and logC=f(m) by changing the microstructure of the steel and, hence, the average fatigue crack growth rates. If the microstructure of a steel contains a ferrite phase or interlamellar ferrite in pearlite colonies, as observed in 0.2% and 0.4% carbon steels tempered at temperatures of 400°C and 600°C, then the mechanism of crack propagation is mainly connected with the formation of striations through the ferrite phase. In this case, the values ofm lie in the range of 2–4. This conclusion is made on the basis of data presented in [9, 10, 14, 15]. For a martensite or tempered martensite microstructure, as in 0.4% carbon steels as-quenched and tempered at 200°C, the predominant mode of fracture is intergranular separation and void coalescence, and the values ofm lie in the range of 4–6. For intermediate values of K, low-carbon steels (0.2%) are weakly sensitive to the mean stresses. This agrees with results obtained for other materials with a ductile mode of crack propagation. For 0.4% carbon steels tempered at 600°C, the exponentm increases from 3.5 to 5 asR increases from 0.1 to 0.85. Most likely, this is explained by an increased role for intergranular separation.Published in Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 31, No. 1, pp. 62–67, January–February, 1995.     

Mechanical and corrosion behavior of plain low carbon dual-phase steels

Dual-phase steels are being used in automobile industries for last three decades. The mechanical properties of dual-phase steels can be altered by varying its martensite volume fraction. However, the benefits obtained in mechanical properties have to be viewed in light of other properties such as corrosion resistance. In this work, dual-phase steels with different volume fractions of martensite are obtained after thermal processing using different intercritical soaking times. The mechanical properties of dual-phase steels such as Vickers hardness and tensile properties are measured. Corrosion properties are evaluated using potentiodynamic polarization test and immersion test. It was observed that the tensile strength and hardness increased and ductility decreased with increase in martensite volume fraction. The corrosion rate for dual-phase steels is found to be lower than that for subcritically heat treated ferrite–pearlite steel. The higher corrosion resistance of dual-phase steels is explained on the basis of microstructural features.     

块体纳米晶工业纯铁在盐酸溶液中的电化学腐蚀行为

通过静态失重试验,动电位极化曲线,电化学阻抗谱(EIS)实验,研究了块体纳米工业纯铁(BNIPI)和粗晶工业纯铁棒(CGPIR)在室温1mol/l盐酸溶液中的腐蚀行为.结果表明,BNIPI与CGPIR相比,开路腐蚀电位Ecorr正向移动114mV,平均腐蚀速度和腐蚀电流Icorr变小,极化电阻Rp增大为1.58倍.BNIPI抗盐酸的腐蚀能力与CGPIR相比,不但没有下降,相反有所增强.使用扫描电子显微镜(SEM)对静态腐蚀失重试样的形貌进行了观察,显示BNIPI上几乎没有点蚀坑出现.     

Modeling the thermomechanical effects on baking behavior of low carbon steels using response surface methodology

Response surface methodology (RSM) was used to study and optimize the effect of thermomechanical treatment on the bake hardening process of low carbon (LC) steels. RSM is a unique modeling approach to replace the costly and time-consuming laboratory simulations to predict the optimal condition for industrial processes. In this study, the RSM based on central composite design (CCD) was used to predict the baking response of low carbon steels. Two models were developed to predict the effects of thermomechanical treatments on the bake hardenability (BH) and final yield stress (FYS) of baked LC steels.     

The inhibition of mild steel corrosion in hydrochloric acid media by two Schiff base compounds

Schiff bases of 2-({-1-methyl-3-[(2-sulfanylphenyl)imino]butylidene}-amino)-1-benzenethiol and 2-({-1,2-diphenyl-2-[(2-sulfanylphenyl)imino]ethylidene}amino)-1-benzenthiol are investigated as corrosion inhibitors in acid solution. Polarization, electrochemical impedance spectroscopy, and weight loss measurements were performed on mild steel in 15% HCl with and without the inhibitors. A significant decrease in the corrosion rate of mild steel was observed in the presence of investigated inhibitors. Polarization curves indicate that both compounds are mixed inhibitors, affecting both cathodic and anodic corrosion currents. The adsorption of inhibitors on mild steel surface in 15% HCl was found to follow Langmuir adsorption isotherm. Thermodynamic adsorption parameters (K _ads, ∆G _ads) of studied Schiff bases were calculated using the Langmuir adsorption isotherm. Activation parameters of the corrosion process such as activation energies, E _a, activation enthalpies, ∆H*, and activation entropies, ∆S*, were calculated by the obtained corrosion currents at different temperatures.     

Effects of hydrogen charge on microscopic fatigue behaviour of annealed carbon steels

The effects of hydrogen charge on cyclic stress‐strain properties, slip band morphology and crack behaviour of annealed medium carbon steels (JIS‐S45C) were studied. The total strain range of the stress‐strain hysteresis loop in the hydrogen‐charged specimen was smaller than that in the uncharged specimen. Localized slip bands were observed in the hydrogen‐charged specimen, while the slip bands were widely and uniformly distributed in the uncharged specimen. It is presumed that the decrease in the total strain range of the hysteresis loop is due to the slip localization caused by the hydrogen charge and cyclic loading. The sites of fatigue crack initiation were mostly at grain boundaries in the uncharged specimen. The sites of crack initiation in the hydrogen‐charged specimen were not only at grain boundaries but also at slip bands inside ferrite grains. These results imply that hydrogen enhances dislocation mobility along slip bands and results in slip localization. These slip bands then attract hydrogen. This mechanism of hydrogen ‐ slip band interaction may play an important role in the hydrogen‐ influenced metal fatigue.