模拟酸雨中钢筋腐蚀行为的研究

利用线性极化法和交流阻抗法对A3钢在模拟酸雨环境下的腐蚀行为进行初步研究,并针对不同酸度、不同离子浓度和不同浸泡时间下的腐蚀结果进行了对比。结果表明：酸度的增加提高了金属的腐蚀速率,SO4^2-和Cl^-在酸雨溶液中对金属阳极溶解起加速作用;随着浸泡时间的延长,金属表面的腐蚀层发生变化,金属的腐蚀速率相应经过了增→减→增的过程。     

Kinetics of mild steel corrosion in aqueous formic acid solutions

Abstract

The kinetics of the corrosion of mild steel in formic acid solutions of different concentrations has been studied at 25, 35 and 45°C. The corrosion rate was evaluated by weight loss and electrochemical polarisation techniques. There is good agreement between the data obtained by the two techniques. The maximum corrosion rate was observed in close vicinity of 20% formic acid solution. The anodic polarisation curves show active corrosion behaviour of mild steel over the whole range of potential at each concentration and temperature. The shape of anodic and cathodic polarisation curves was found to be almost independent of the temperature and the concentration of formic acid. However, the curves bodily shift towards the lower or higher current density side with the change in the concentration of the electrolyte. With the increase in temperature, the shift of polarisation curve regularly occurs towards the higher current density side. The surface morphology of the specimens has been studied by scanning electron microscopy. The micrographs indicate uniform corrosion of mild steel in formic acid solution.

On a étudié la cinétique de corrosion de l’acier au carbone en solutions d’acide formique à différentes concentrations, à 25, 35 et 45°C. On a évalué la vitesse de corrosion par des techniques de perte de poids et de polarisation électrochimique. Il y a un bon accord entre les données obtenues par les deux techniques. On a observé la vitesse maximale de corrosion dans une solution de près de 20% d’acide formique. Les courbes de polarisation anodique montrent un comportement de corrosion active de l’acier au carbone pour la gamme complète de potentiel à chaque concentration et température. On a trouvé que la forme des courbes de polarisation anodique et cathodique était presque indépendante de la température et de la concentration de l’acide formique. Cependant, le c?ur des courbes se déplace du côté d’une densité de courant plus faible ou plus élevée avec un changement de concentration de l’électrolyte. Avec une élévation de la température, le déplacement de la courbe de polarisation se produit régulièrement du côté d’une densité de courant plus élevée. On a étudié la morphologie de la surface des échantillons au moyen du microscope électronique à balayage. Les micrographes indiquent une corrosion uniforme de l’acier au carbone dans une solution d’acide formique.     

X120管线钢在酸性土壤模拟溶液中的均匀腐蚀行为

选用我国华南地区酸性土壤的典型代表——鹰潭土壤为腐蚀介质,按照GB12124-88标准,采用失重法测量了X120管线钢在模拟溶液中的短期均匀腐蚀速率,并用电化学方法同步测量了各时间段的瞬时腐蚀速率;采用SEM和XRD观察并分析了试样经过480 h腐蚀后表面锈层形貌及腐蚀产物组成。结果表明,用线性极化曲线模拟法能较好地预测腐蚀速率,发现以FeOOH和Fe3O4为主的内锈层能较好地阻碍腐蚀过程的进行。随着时间的推移,X120管线钢的阴极腐蚀过程由最初的浓差极化控制为主逐步转变为以活化极化控制为主的均匀腐蚀。     

SXD-6型钢铁酸洗缓蚀抑雾剂试验结果及分析

通过对SXD_6型钢铁酸洗缓蚀抑雾剂实验室试验结果的分析 ,及现场生产使用结果分析 ,该产品对酸洗质量的提高、铁基的缓蚀、抑制酸雾挥发起较好作用 ,达到了提高质量、降低成本的作用 .     

Experimental and theoretical studies on corrosion inhibition of mild steel in hydrochloric acid by thiosemicarbazone of Schiff bases

The inhibiting action of the synthesised thiosemicarbazones, namely, 4[N-(4′-chlorobenzalidene)amino] antipyrinethiosemicarbazone, 4[N-(benzalidene)amino] antipyrinethiosemicarbazone, and 4[N-(4′-methoxybenzalidene)amino] antipyrinethiosemicarbazone towards the corrosion behaviour of mild steel in 4M HCl solution was studied by using weight loss, potentiodynamic polarisation and electrochemical impedance spectroscopy techniques. Scanning electron microscopy was used to characterise the surface morphology of the mild steel specimens in the presence and absence of inhibitor. The experimental results show that the inhibition efficiency increases as the concentration of the inhibitors were increased. The polarisation measurements indicate that the studied inhibitors act as mixed inhibitor. The adsorption of studied inhibitors on mild steel surface obeys Langmuir adsorption isotherm. Quantum chemical calculations were carried out by using semi-empirical AM1 method. A good correlation between the theoretical data and the experimental results was found.

On a étudié l’action inhibitrice des thiosemicarbazones synthétisées, c’est-à-dire, 4[N-(4′-chlorobenzalidène)amino] antipyrinethiosemicarbazone, 4[N-(benzalidène)amino] antipyrinethiosemicarbazone, et 4[N-(4′-méthoxybenzalidène(amino] antipyrinethiosemicarbazone par rapport au comportement à la corrosion de l’acier doux dans une solution d’HCl 4M en utilisant les techniques de perte de poids, de polarisation potentiodynamique et de spectroscopie d’impédance électrochimique. On a utilisé la microscopie électronique à balayage pour caractériser la morphologie de la surface des échantillons d’acier doux avec ou sans inhibiteur. Les résultats expérimentaux montrent que l’efficacité de l’inhibition augmente avec l’augmentation de la concentration des inhibiteurs. Les mesures de polarisation indiquent que les inhibiteurs étudiés agissent comme un inhibiteur mixte. L’adsorption des inhibiteurs étudiés à la surface de l’acier doux obéit à l’isotherme d’adsorption de Langmuir. On a effectué des calculs chimiques quantiques en utilisant la méthode semi-empirique AM1. On a trouvé une bonne corrélation entre les données théoriques et les résultats expérimentaux.     

Grain-boundary corrosion of type 304 stainless steel by cesium oxides

When austenitic stainless steel (300 series) is exposed to cesium oxides in the tempera-ture range from 450° to 700°C the grain boundaries are attacked preferentially. The penetration of cesium oxides into the grain boundaries of AISI Type 304 stainless steel has been studied as a function of time and temperature. These investigations have established that the penetration kinetics are linear in time, the activation energy for the process is 19 kcal/mole, and the rate of penetration is fairly insensitive to carbide precipitation and precipitate composition and morphology. The kinetics of the process are approximately an order of magnitude faster than those observed for some reactor (U, Pu) oxide fuel elements clad with Type 304 stainless steel under fast-flux irradiations, and the results are discussed qualitatively.     

MnS夹杂物诱发钢材点蚀综述

MnS夹杂物诱发钢材点蚀,对钢材服役寿命、工作生产安全和社会经济发展产生巨大危害。首先,分析了MnS夹杂物诱发钢材点蚀的机理,包括电偶腐蚀机理、S和Cl-协同作用机理、封闭区域加速点蚀机理、贫铬区机理和微缝隙机理;其次,汇总了MnS夹杂物大小、形貌、分布,Cl-浓度、温度和应力对MnS夹杂物诱发钢材点蚀的影响;然后,总结了钢材防腐蚀的常用措施;最后,展望了防止MnS夹杂物诱发钢材点蚀的未来研究方向。     

表面纳米化316L不锈钢在酸性介质中腐蚀性能的研究

采用表面机械研磨处理(SMAT)在316L不锈钢上制备出纳米结构表层,研究表层纳米化组织的腐蚀性能. 结果表明:经过60 min SMAT后,样品表面形成了一定厚度的纳米表层.显微组织. 由晶粒尺寸为10～30 nm的双相组织(马氏体和奥氏体)组成. 表层腐蚀性能在c(H2SO4)=0.05 mol/L和c(Na2SO4)=0.25 mol/L构成的腐蚀介质中下降.     

High-temperature corrosion of heat-resistant chromonickel steel

To understand the rapid decline in the working life of 40X24H12CЛ steel gratings in roasting cars in changing operating conditions, the gratings are studied over different operating periods. On that basis, the mechanism of corrosive failure is determined, and the intercrystallite corrosion in the steel after operation for more than three months is analyzed. The surfaces of the part where intercrystallite corrosion is most intense are identified. The influence of the grating’s operating conditions on intercrystallite corrosion is evaluated. Means of enhancing the grating quality are established.     

高温浓硫酸中氟离子掺入对不锈钢耐蚀性能的影响

采用浸泡法和电化学测试方法结合扫描电镜和能谱仪研究了高温浓硫酸中氟离子的掺入对304、2507以及904L三种不锈钢耐蚀性能的影响.结果表明:氟离子的掺入对三种不锈钢在浓硫酸中的腐蚀具有抑制作用,综合来看,904L具有更为稳定的耐蚀性能;三种不锈钢在高温浓硫酸中由于生成了热力学不稳定的硫化镍而产生了活化转钝化现象,而掺入氟离子会和硫离子发生竞争使其排挤出电极表面,氟离子与镍离子结合形成另外一种更稳定的阻挡层使不锈钢耐蚀性提高.     

Inhibition of acid sialidase by inorganic sulfate

Sulfated glycosaminoglycans are known to inhibit mammalian acid-active sialidase. Although the inhibition depends clearly on the presence of sulfate groups on these macromolecules, there was no information on the intrinsic inhibitory potency of inorganic sulfate. In this study, we demonstrate that inorganic sulfates inhibit acid-active Mu-Neu5Ac sialidase of U937 cells. This inhibition was found to be reversible and it appeared to be of the mixed competitive type. Sulfate-induced inhibition was also observed in other cells as well as with other substrates such as sialyl lactose and bovine mixed brain gangliosides. We conclude that the intrinsic inhibitory potency of sulfate groups may be significantly involved in the inhibition of acid-active sialidase by sulfated glycosaminoglycans. In addition, inorganic sulfate by its apparent potency to selectively inhibit acid sialidases might constitute an interesting tool for the characterisation of the minor forms of sialidases occurring in mammalian cells.     

甲酸浓度对316L不锈钢腐蚀钝化?活化转变行为的影响

为深入认识316L不锈钢在甲酸溶液中的钝化-活化转变行为,在90 ℃、质量分数为0~30%的甲酸溶液中对316L不锈钢进行全浸试验和阳极极化曲线测试。研究了甲酸质量分数对316L不锈钢腐蚀速率、腐蚀形貌、开路电位、初始钝化电位、临界电流密度、钝化电流密度和钝化膜破裂电位的影响规律,分析了H+ 和HCOO? 含量对活化区、过渡区和钝化区阳极反应的影响机制。结果表明,316L不锈钢在甲酸溶液中发生非均匀的全面腐蚀。当甲酸质量分数达到30%、腐蚀速率为1.2×10?3 mm·a?1时,316L不锈钢就具有明显的钝化?活化转变。随着甲酸质量分数增加,316L不锈钢的初始钝化电位正移、临界电流密度增大、钝化电流密度增大、钝化膜破裂电位负移。甲酸溶液中H+ 和HCOO? 含量的增加,会加速316L不锈钢活性溶解,抑制钝化膜生长,促进钝化-活化转变。      

Modeling microbiologically influenced corrosion of N-80 carbon steel by fuzzy calculus

To investigate microbiologically influenced corrosion (MIC) risk using fuzzy Iogics, weight loss study of N-80 steel was carried out under three circumstances: (1) abiotic, (2) completely biotic (no biocide), and (3) biotic with almost enough biocide (underlined are fuzzy expressions). The microorganism employed was sulphate-reducing bacteria (SRB). Also, effective concentration of a biocide to kill the bacteria was investigated and recorded. Using fuzzy logics and calculus, it was shown that (fuzzy) probability of risk of MIC in the biotic system without biocide was 60 pct, whereas with almost enough biocide, the risk was 50 pct. Different from being absolute risk values, these risk values showed that fuzzy logics methods had the capability of showing how vulnerable a system could be to MIC.     

在混凝土模拟孔隙液中癸二酸二异辛酯的缓蚀特性研究

采用动电位极化曲线和电化学阻抗谱研究了癸二酸二异辛酯在模拟混凝土孔隙液中对钢筋的保护作用.癸二酸二异辛酯的加入导致混凝土钢筋的腐蚀电位正移,对钢筋的阳极电化学过程有抑制作用.其缓蚀效果随癸二酸二异辛酯浓度增加而增加,当癸二酸二异辛酯的浓度为2%时,对含有400mg/L Cl^-的混凝土模拟液中钢筋电极的缓蚀效率为78.5%.氯离子含量是影响钢筋腐蚀性能和癸二酸二异辛酯阻锈剂作用的重要因素.癸二酸二异辛酯能够在钢筋表面形成沉淀性保护膜.     

Inhibition in the human urinary bladder by gamma-amino-butyric acid

OBJECTIVE: To investigate the effects of gamma-amino-butyric acid (GABA) on detrusor activity in man to determine whether it has any inhibitory effect on detrusor contraction. The inhibitory neurotransmitter GABA has been found in mammalian urinary bladders and the effects of GABA on detrusor activity in the rabbit bladder has previously been described [1]. MATERIALS AND METHODS: Human detrusor muscle strips, obtained at cystectomy, were made to contract by electrical stimulation of their autonomic nerves or by the addition of carbachol in a superfusion apparatus. GABA and its analogues were added to the superfusion chamber and any changes in the responses were measured. RESULTS: The electrically evoked nerve-mediated contractions in human bladder muscle were exclusively cholinergic. GABA inhibited nerve-mediated contractions in human detrusor muscle-strips by the activation of the GABAB receptor, since baclofen (a GABAB receptor agonist) produced similar inhibition and muscimol (a GABAA receptor agonist) did not. There was no inhibition of carbachol-mediated contractions by GABA. CONCLUSION: This in vitro study shows that GABA has a peripherally mediated inhibitory effect on excitatory neurotransmission in human detrusor muscle. The site of action is on the post-ganglionic nerves and appears to be mediated via the GABAB receptor.     

Hydrogen-facilitated corrosion and stress corrosion cracking of austenitic stainless steel of type 310

The effects of hydrogen précharge and stress on anodic dissolution for Type 310 austenitic stainless steel (ASS) have been investigated. An experiment determining the effect of hydrogen on stress corrosion cracking (SCC) was carried out in a boiling 42 pct MgCl₂ solution and in a 2.5 mo/L H₂SO₄ + 1 mol/L HC1 solution. The results showed that both hydrogen and stress would increase the dissolution rate, and the effects of hydrogen and stress on the dissolution rate were synergistic rather than simply additive. Hydrogen lowered the threshold stress and the shortened fracture time of SCC in a boiling MgCl₂ solution by a factor of 1/5 and 10, respectively.     

Microscale investigations of the metal-dusting corrosion mechanism on mild steel

The internal and external products from metal-dusting corrosion of a mild steel specimen have been investigated, with the intention of further exploring the corrosion reaction mechanism. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have been employed. A section of a steel tube, which had been subjected to heavily corrosive attack under controlled conditions, was studied. Electron-transparent TEM samples from this specimen were observed in the cross-sectional and plan-view orientations of the corrosion interface. Deposit on the corroded surface contained amorphous carbon, graphitic crystalline carbon, and decomposition products. Supersaturated cementite is an intermediate reaction product and was present at the surface of the exposed alloy. Surface cementite was seen to decompose locally into the graphite, where graphite basal planes were oriented perpendicular to the cementite surface. Iron was transported through the graphite, and the mild steel disintegrated by continuous formation and disintegration of the surface cementite. The observations are discussed with reference to the prevailing model mechanism for metal-dusting corrosion.     

耐候钢和集装箱钢板标准研究及关系阐述

综合论述了耐腐蚀钢的分类和特点,主要介绍了三种耐大气腐蚀钢的定义和使用范围。详细阐述耐大气腐蚀钢国内外标准的发展历程,以GB/T4171-2000高耐候结构钢标准和GB/T18982-2003集装箱用耐腐蚀钢板及钢带标准为例,分析我国耐候钢标准的主要内容和与国外先进标准的对比,以及阐明了耐候钢和集装箱钢板标准的关系。     

经济型耐腐蚀钢中氧作用的研究

为了冶炼不同氧含量的碳素船体钢,通过机械性能试验和周浸试验研究了钢中氧含量对钢材腐蚀性能和机械性能的影响。结果表明,在连铸生产许可的氧范围内,随着钢水脱氧程度的减弱,钢中氧质量分数增加,钢材的平均腐蚀率略有下降,而耐点蚀性能有较明显增强,变化曲线的高氧端比低氧端平均点蚀深度下降约22.7%。弱脱氧钢的机械性能符合规范要求,可达到D级钢水平。分析认为,氧提高钢材耐蚀性的原因主要是固溶氧可提高铁的热力学稳定性,提高了蚀孔内铁的腐蚀电位,降低了蚀坑扩展速度。氧作为耐蚀元素应用可以显著降低耐蚀钢的成本,提高经济性。