Effective inhibition of mild steel corrosion in hydrochloric acid using EBIMOT,a 1, 3, 4-oxadiazole derivative bearing a 2-ethylbenzimidazole moiety: Electro analytical,computational and kinetic studies

A new organic compound, 5-((2-ethyl-1Hbenzo[d]imidazol-1-yl)methyl)-1,3,4-oxadiazole-2-thiol (EBIMOT) has been investigated for its efficacy in the corrosion inhibition of mild steel in 0.5?M HCl at three different temperatures by classical weight loss technique, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) methods. EBIMOT shows high inhibition activity through adsorption and this phenomenon was found to obey Langmuir adsorption isotherm. The kinetic parameters were also derived using the experimental data. The quantum chemical DFT studies were used to correlate the interrelation of inhibition efficiency and molecular structure.     

Synergistic interaction of 2-amino 4-methyl benzothiazole (AMBT) and benzotriazole (BTZ) offers excellent protection to mild steel exposed in acid atmosphere at elevated temperatures: Electrochemical,computational and surface studies

The synergistic interactions and corrosion protection properties of 2-amino 4-methyl benzothiazole, (AMBT) and 1, 2, 3-benzotriazole (BTZ) have been studied for mild steel in HCl at elevated temperatures. The extent of synergistic interaction increases with temperature. The methods of study include the conventional weight loss studies, computational screening, surface characterization and electrochemical studies. Quantum chemical approach was used to calculate some electronic properties of the molecules and to ascertain the synergistic interaction, inhibitive effect and molecular structures. The corrosion inhibition efficiencies and the global chemical reactivity relate to parameters like total energy, E_HOMO, E_LUMO and gap energy (ΔE). Condensed atom Fukui functions also calculated using DFT at B3LYP/6-31G* level, and were found to be correlating with the experimental results.     

Phytochemical screening and corrosion inhibitive behavior of Pterolobium hexapetalum and Celosia argentea plant extracts on mild steel in industrial water medium

Preliminary phytochemical screening was carried out for methanolic extracts of Pterolobium hexapetalum (PH) and Celosia argentea (CA). Methanolic extracts of PH and CA were studied as corrosion inhibitors for mild steel in industrial water medium using mass loss and electrochemical techniques. The adsorption of both PH and CA extracts on mild steel surface followed Langmuir isotherm. The electrochemical impedance spectroscopy (EIS) measurements showed that the charge transfer resistance increases with increasing concentration of extracts. Various thermodynamic parameters were evaluated and discussed. Scanning electron microscopy (SEM) was used to analyze the surface adsorbed film. Further, antioxidant activity of the plant extracts was determined and correlated with the results obtained with inhibition efficiency.     

Novel naphthenate surfactants based on petroleum acids and nitrogenous bases as corrosion inhibitors for C1018-type mild steel in CO2-saturated brine

The efficiency of two natural naphthenate surfactants (Naphthenic-dimethylamine and Naphthenic-diethylamine complexes), as corrosion inhibitors for mild steel in CO₂-saturated 1% NaCl solution, has been determined by linear polarization resistance corrosion rate and potentiodynamic polarization measurements. These compounds inhibit corrosion even at very low concentrations (25 ppm), and Naphthenic-diethylamine complex is the best inhibitor giving maximum inhibition efficiency (99.76) at 100 ppm. Polarization curves indicate that, the two investigated compounds are mixed inhibitors, affecting both cathodic and anodic corrosion currents. Adsorption of naphthenate surfactants on the mild steel surface is in good agreement with the Langmuir adsorption isotherm model, and the calculated Gibbs free energy values confirm the chemical nature of the adsorption. Energy dispersive X-ray fluorescence microscopy (EDRF) and scanning electron microscope (SEM) observations confirmed the existence of such an adsorbed film on the mild steel surface.     

Thermodynamic,adsorption and electrochemical studies for corrosion inhibition of carbon steel by henna extract in acid medium

Corrosion inhibition of carbon steel in the presence of different concentrations of aqueous extract from henna leaves in 1 M HCl solution has been studied using the weight loss and potentiodynamic polarization techniques. The effect of temperature on the corrosion behavior of carbon steel was studied in the temperature range 293–333 K. The inhibition efficiency increases with increasing inhibitor concentration but decreases with increasing temperature. The activation and free energies for the inhibition reactions support the mechanism of physical adsorption. The adsorption of henna extract on C-steel surface is endothermic, spontaneous and consistent with the Langmuir adsorption isotherm. The potentiodynamic polarization measurements indicate that henna extract acts as a mixed inhibitor. Surface and protective film analysis have been carried out using; energy dispersive X-ray (EDX), scanning electron microscopy (SEM), Fourier transforms infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) analysis.     

耐浓硫酸新型铸造合金钢研究

设计了新型铸造合金钢的化学成分,研究了该合金钢的显微组织及其腐蚀行为。由Ｃｒ、Ｎｉ、Ｓｉ、Ｍｏ 及Ｃｕ 多元合金化的新型铸造合金钢,经１ ２００ ℃下２ ｈ 水冷固溶化处理后,具有良好的耐浓硫酸腐蚀性能和较高的抗点蚀性能。该合金钢敏化处理后,仍具有较好的抗晶间腐蚀性能。     

Cr5Mo钢在高温环烷酸中的腐蚀研究

采用CJF-2L型高温高压反应釜进行旋转挂片试验,通过腐蚀失重法和腐蚀形貌分析研究了Cr5Mo钢在高温环烷酸介质中的腐蚀行为规律.试验结果表明：实验酸值、温度及流速均显著影响Cr5Mo钢的腐蚀速率.Cr5Mo钢的腐蚀速率随着介质酸值的增加而增大,与介质酸值平方根呈线性关系,但增加酸值对Cr5Mo钢的腐蚀速率影响有限;随着温度的升高,腐蚀速率先增大后减小,在280℃时腐蚀速率达到最大值,为0.262 3 mm/a,不符合Arrhenius公式;腐蚀速率随流速增加而变大,流速对腐蚀速率影响较大.Cr5Mo钢在高温环烷酸介质中出现严重点蚀,点蚀坑的数量随酸值、温度及流速增大而增大,严重威胁安全生产,因此建议Cr5Mo钢在高温环烷酸介质中应监护使用.     

Novel surfactants incorporated with 1,3,5-triethanolhexahydro-1,3,5-triazine moiety as corrosion inhibitors for carbon steel in hydrochloric acid: Electrochemical and quantum chemical investigations

The main objective of this work was to examine the corrosion inhibition ability of three novel surfactant molecules synthesized from 1,3,5-triethanolhexahydro-1,3,5-triazine, which named (I, II and III). The chemical structure of these surfactants was confirmed by FT-IR and ¹H NMR spectroscopy. Also the surface active properties for the synthesized compounds were calculated. The effect of these surfactants on carbon steel in a solution of 1 M HCl was studied using mass-loss and electrochemical measurements. Protection efficiencies were found to be 93.1%, 90.7%, and 87% for III, II, and I, respectively. The order of increasing inhibition efficiency was correlated with increasing the number of ethylene oxide units. Potentiodynamic polarization curves indicated that the prepared surfactants acted as mixed type inhibitors. Adsorption of the inhibitor obeys the Langmuir isotherm. Quantum chemical calculations based on ab initio method were performed on I, II and III. The molecular structural parameters, such as the frontier molecular orbital energy HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital), the charge distribution and the fraction of electrons (ΔN) transfer from inhibitor to carbon steel were calculated and discussed.     

长庆某气田完井液缓蚀剂的研究和应用

长庆某气田平均井深为3400m，储层上部有多个厚水层，通过定量测定各层的犄蚀速率，从上层到下层的纵向腐蚀分布是腐蚀速率逐渐增大。按照NACERP0775—91规定，腐蚀速率高，数值区间处于中度腐蚀和严重腐蚀之间，而且固井工艺采用局部固井降低成本的措施。提出了使用完井液复合缓蚀荆来延缓外部水对套管的腐蚀。通过对多种缓蚀剂的成分、配伍性和成膜、缓蚀性能的对比评价，优选出了适应该气田完井液体系的缓蚀剂MIG，经室内电化学和高温高压等试验，其缓蚀率达到86％以上，与钻井液配伍性能稳定且价格适中。现场2口井的应用表明，加入MIG缓蚀剂对钻井完井液的性能基本无影响，用前置液对固井段井筒环空钻井液和套管外壁清洗后，MIG复合缓蚀剂不影响固井第一、第二胶结面的质量，并且现场施工方便、简单、安全。     

Evaluation of N-(3-(dimethyl hexadecyl ammonio)propyl) palmitamide bromide as cationic surfactant corrosion inhibitor for API N80 steel in acidic environment

A new cationic surfactant named (N-(3-(dimethyl hexadecyl ammonio)propyl) palmitamide bromide has been evaluated as corrosion inhibitor for API N80 Steel Pipelines in 1M HCl solution. Four different techniques have been utilized for studying the corrosion behavior of the synthesized cationic amphipathic corrosion inhibitor. The prepared corrosion inhibitor was evaluated at five different temperatures 25, 30, 40, 50 and 60?°C, using weight loss technique. The three other techniques which are potentiodynamic polarization, Electrochemical impedance (EIS) and Electrochemical frequency modulation (EFM) were used for evaluation at room temperature (25?°C?±?1). The results outlined that the synthesized DMHPP amphipathic corrosion inhibitor was good inhibitor and their inhibition efficiencies were directly proportional with both the inhibitor concentration and temperature. Polarization curve revealed that the studied inhibitor act as a mixed-type of inhibitor. The adsorption of the used inhibitor led to a reduction in the double layer capacitance and an increase in the charge transfer resistance. The adsorption behavior of the amphipathic inhibitor obey Langmuir adsorption model. The change in free energy of adsorption of the synthesized inhibitor range from ?40.5 to ?45.5?kJ?mol^?1 as an indication for chemisorption process between inhibitor and steel. A clear correlation was found between corrosion inhibition efficiency and theoretical parameters obtained using density functional theory (DFT).     

P110钢高温高压CO2腐蚀行为研究

运用腐蚀失重、腐蚀表面成分分析和电化学测量技术,在模拟油田现场腐蚀环境中研究P110油管钢的高温高压腐蚀行为.研究结果表明,随着试验时间的延长,腐蚀速率逐渐降低.在试验时间达到72 h后,腐蚀速率降低的趋势变缓;阳极极化曲线上出现了类似于钝化的现象;阴极极化曲线的Tafel斜率变化较大,P110钢的阴极反应趋势已经不同.     

Adsorption and inhibition behavior of a novel Schiff base on carbon steel corrosion in acid media

In this study, the inhibition effect of 2,2′-(heptane-1,7-diylbis(azanylylidene)bis-(methanylylidene))diphenol (HAMD) on carbon steel corrosion in 0.5 mol L⁻¹ H₂SO₄ solution was studied. Weight loss and electrochemical techniques such as open circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to inspect the efficiency of HAMD as corrosion inhibitor. Scanning electron microscopy (SEM) and energy dispersion X-ray (EDAX) were used to characterize the steel surface. Polarization measurements indicated that, the studied inhibitor acts as mixed-type inhibitor. The adsorption of HAMD molecules on the carbon steel surface obeys Langmuir adsorption isotherm.     

普通油井管钢在CO2和H2S共存环境中的腐蚀实验研究

采用高温高压腐蚀仪对普通油井管钢N80进行了CO2、CO2和H2S共存条件下的腐蚀实验,测量了平均腐蚀速率,结果表明:90℃时,CO2腐蚀环境中加入不同含量的H2S后,试样表面腐蚀状况有较大改善,腐蚀速率均有所降低;保持CO2分压恒定,随着CO2和H2S分压比增加,腐蚀速率在分压比为100时出现峰值;保持H2S分压恒定...     

Effect of solution pH on the electrochemical behaviour of AISI 304 austenitic and AISI 430 ferritic stainless steels in concentrated acidic media

In this study, the effect of solution pH on the electrochemical behaviour of AISI 304 austenitic and AISI 430 ferritic stainless steels at open circuit potential (OCP) in concentrated acidic solutions was studied. Polarization curves showed that the corrosion current density of both stainless steels increased with decreasing pH. Mott–Schottky analysis revealed that passive films formed on AISI 304 and AISI 430 stainless steels behave as n-type and p-type semiconductors and the donor and acceptor densities increased with decreasing pH. Electrochemical impedance spectroscopy (EIS) results showed that the reciprocal capacitance of the passive film is directly proportional to its thickness which decreases with decreasing pH. Thus for both austenitic and ferritic stainless steels in acidic solutions, increasing the solution pH offers better conditions for forming passive films with higher protection behaviour, due to the growth of much thicker and less defective films.     

高温高流速冲蚀实验装置及Cr5Mo钢在环烷酸中的冲蚀研究

设计制造了一套高温高流速冲刷腐蚀实验测试装置,并利用该装置对Cr5Mo钢在230～248℃、流速为47m/s、酸值为8.3mgKOH/g变压器油的条件下,进行了冲蚀实验.由该装置测得的腐蚀速率与现场条件下的腐蚀速率具有可比性.它可用来评价高温高流速条件下材料的冲刷腐蚀行为和进行冲刷腐蚀机理研究,并为材料及各种防护手段提供测试条件.