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排序方式: 共有612条查询结果,搜索用时 15 毫秒
21.
The objective of this study was to investigate the correlation of phenolic compositions and corrosion inhibition properties of Rhizophora apiculata bark extracts as affected by nine solvent systems. Several phenolic compositions, namely, total phenolic content (TPC), total flavonoid content (TFC), condensed tannin content (CTC) were investigated. In addition, the inhibitive actions of tannin extracts on mild steel in 1 M HCl solution were studied by potentiodynamic polarization and electrochemical impedance spectroscopy. The results showed that extraction solvents had significant effects on TPC, TFC, CTC and inhibition properties of extracts. A correlation between CTC and inhibition properties of R. apiculata bark extracts was revealed. 相似文献
22.
D. Thirumoolan Vikas A. Katkar G. Gunasekaran Tapan Kanai K. Anver Basha 《Progress in Organic Coatings》2014
Hyperbranched poly(cyanurateamine) (POCYAM) was tested as a novel corrosion inhibitor for mild steel in 0.5–3 M HCl using chemical and electrochemical techniques at 25–70 °C. The results show that this compound has good corrosion inhibiting properties for mild steel in HCl at very low concentrations. Corrosion inhibition efficiency rises with POCYAM concentration. The adsorption of the POCYAM onto the mild steel surface obeys Langmuir adsorption isotherm model. The inhibition mechanism was further corroborated by the values of thermodynamic parameters obtained from the experimental data. 相似文献
23.
武器装备论证的柔性仿真建模研究 总被引:2,自引:1,他引:1
论证仿真是支持武器装备论证的重要方法和关键技术之一,如何克服领域建模仿真系统之间互操作性的缺乏,使一些模型和专业化程度高的仿真工具,在多领域、全过程协作和资源共享成为可能是装备论证工作的一项重要工作。分析了武器装备论证问题及其建模仿真方法的特点,将混合异构层次化建模思想应用到装备论证仿真建模过程当中,较好地反映了论证系统全面和多层次结构的性质。并给出了一种基于图形过程的组合模型生成建模方法,为武器装备论证这类复杂系统的仿真建模问题提供了一次有益的尝试。同时说明了这样一个结论:改进和扩展单一的建模技术、走复合建模技术的道路,是解决大规模复杂系统建模问题的有效途径。 相似文献
24.
The purines and its derivatives, such as, guanine, adenine, 2,6-diaminopurine, 6-thioguanine and 2,6-dithiopurine, were investigated as corrosion inhibitors for mild steel in 1 M HCl solution by weight loss measurements, electrochemical tests and quantum chemical calculations. The polarization curves of mild steel in the hydrochloric acid solutions of the purines showed that both cathodic and anodic processes of steel corrosion were suppressed. The Nyquist plots of impedance expressed mainly as a depressed capacitive loop with different compounds and concentrations. For all these purines, the inhibition efficiency increased by increasing the inhibitor concentration, and the inhibition efficiency orders are 2,6-dithiopurine > 6-thioguanine > 2,6-diaminopurine > adenine > guanine with the highest inhibiting efficiency of 88.0% for 10−3 M 2,6-dithiopurine.The optimized structures of purines, the Mulliken charges, molecular orbital densities and relevant parameters were calculated by quantum chemical calculations. The quantum chemical calculation results inferred that the adsorption belong to physical adsorption, which might arise from the π stacking between the π electron of the purines and the metal surface. 相似文献
25.
This paper describes desulfurization characteristics of low sulfur coals prior to combustion and optimum conditions of three
different desulfurization processes. These processes include two thermal treatment processes (mild pyrolysis and air oxidation)
and an H2O2 leaching process. Dual processes composed of thermal and leaching processes were also evaluated. Low sulfur coals employed
were two imported bituminous coals and two domestic anthracite coals. The optimum reaction temperatures and times of the thermal
processes were 500–550 °C and 15–20 minutes, respectively. The optimum condition for the leaching process was obtained when
the experiment carried out for 60 min at 90 °C using 30% H2O2. The dual process showed the best sulfur removal efficiency as expected among the evaluated processes.
This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University. 相似文献
26.
Long-term atmospheric corrosion of mild steel 总被引:3,自引:0,他引:3
A great deal of information is available on the atmospheric corrosion of mild steel in the short, mid and even long term, but studies of the structure and morphology of corrosion layers are less abundant and generally deal with those formed in just a few years. The present study assesses the structure and morphology of corrosion product layers formed on mild steel after 13 years of exposure in five Spanish atmospheres of different types: rural, urban, industrial and marine (mild and severe). The corrosion layers have been characterised by X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Long-term corrosion is seen to be more severe in the industrial and marine atmospheres, and less so in the rural and urban atmospheres. In all cases the corrosion rate is seen to decrease with exposure time, stabilising after the first 4–6 years of exposure. The most relevant aspects to be noted are (a) the great compaction of the rust layers formed in the rural and urban atmospheres, (b) the formation of hematite and ferrihydrite phases (not commonly found) in the industrial and marine atmospheres, respectively and (c) identification of the typical morphological structures of lepidocrocite (sandy crystals and flowery plates), goethite (cotton balls structures) and akaganeite (cotton balls structures and cigar-shaped crystals). 相似文献
27.
The metastable pitting behaviors of mild steel in bicarbonate and nitrite solutions containing Cl 总被引:1,自引:0,他引:1
The metastable pitting behaviors of mild steel in NaHCO3 + NaCl and NaNO2 + NaCl solutions were studied with electrochemical methods. In NaHCO3 + NaCl solution the potential range between metastable pitting potential Em and pitting potential Eb is relatively large, and most of the current fluctuations are individual. While in NaNO2 + NaCl solution the Em and Eb values are much higher and the potential range between them is very narrow, leading to overlapped current peaks. The changes of Em and Eb with chloride concentration follow similar tendency. In both testing solutions, the repassivated metastable pitting sites are prone to become preferential sites for following metastable pits to nucleate, leading to accumulated corrosion damages on the surface. Mild steel shows stronger passivity in NaNO2 + NaCl solution than in NaHCO3 + NaCl solution, which explains the higher pitting resistance of the steel in the former. In addition, the competitive adsorption of anions also plays an important role in the increase of Em and Eb, especially in inhibiting nucleation of metastable pits. 相似文献
28.
Changes in atmospheric corrosion rate caused by chloride ions depending on rain regime 总被引:1,自引:0,他引:1
Plain carbon steel and copper samples were exposed in two atmospheric test stations located in Havana, Cuba and Medellin, Colombia. Samples were submitted to accelerated outdoor test by intermittent spraying of a salt solution (SCAB test) according to ISO 11474:98.A remarkable difference in the acceleration rate of chloride ions for mild steel and copper between Cuban and Colombian stations was determined. Differences in rain amount and frequency between Havana and Medellin are noticeable. The influence of rain seems to be important in determining the acceleration rate of chloride ions on steel and copper due to its washing effect. A model for the influence of the interaction between rain characteristics and chloride deposition rate on mild steel and copper corrosion behaviour with time is proposed. Data fit very well to the proposed model. It is concluded that rain regime should be taken into account in order to determine the real acceleration rate caused by chloride ions in atmospheric conditions. 相似文献
29.
30.
Sodium phthalamates as corrosion inhibitors for carbon steel in aqueous hydrochloric acid solution 总被引:2,自引:0,他引:2
Eugenio A. Flores Octavio Olivares Natalya V. Likhanova Marco A. Domínguez-Aguilar Noel Nava Diego Guzman-Lucero Mónica Corrales 《Corrosion Science》2011,53(12):3899-3913
Three compounds of N-alkyl-sodium phthalamates were synthesized and tested as corrosion inhibitors for carbon steel in 0.5 M aqueous hydrochloric acid. Tests showed that inhibitor efficiencies were related to aliphatic chain length and dependent on concentration. N-1-n-tetradecyl-sodium phthalamate displayed moderate efficiency against uniform corrosion, 42–86% at 25 °C and 25–60% at 40 °C. Tests indicated that compounds behave as mixed type inhibitors where molecular adsorption on steel followed Langmuir isotherm, whereas thermodynamic suggested that a physisorption process occurred. XPS analysis confirmed film formation on surface, where Fe+2 complexes and Fe+2 chelates with phthalamates prevented steel from further corrosion. 相似文献