Inhibitive effect of <Emphasis Type="Italic">Xylopia ferruginea</Emphasis> extract on the corrosion of mild steel in 1M HCl medium

The alkaloid content of the leaves and stem bark of Xylopia ferruginea plant was isolated and tested for its anticorrosion potential on mild steel corrosion in a hydrochloric acid medium by using electrochemical impedance spectroscopy, potentiodynamic polarization measurement, scanning electron microscopy (SEM), and Fourier transform infra red (FTIR) analysis. The experimental results reveal the effective anticorrosion potential of the plant extract. The mixed mode of action exhibited by the plant extract is evidenced from the polarization study. SEM images proof the formation of a protective layer over the mild steel surface, and this is supported by the FTIR study. The possible mode of the corrosion inhibition mechanism has also been discussed.     

酸介质中三氮唑苯胺化合物在Q235钢表面的吸附及其缓蚀作用

采用动电位极化、交流阻抗、失重测试等方法研究了一种新合成的三氮唑-苯胺化合物(DOT)在1mol/L HCl中对Q235钢的缓蚀性能,其腐蚀形貌用电子显微镜进行观察,结合吸附热力学和动力学,讨论其缓蚀机理。结果表明,在酸溶液中,DOT能同时抑制碳钢腐蚀的阴、阳极反应过程,是一种优异的混合型缓蚀剂,其浓度为0.001mol/L时缓蚀效率可达96%以上。吸附热力学表明DOT在碳钢表面上的吸附过程为放热过程,其在碳钢表面的吸附服从Langmuir等温式,属于物理和化学吸附。     

有机缓蚀剂对钢筋的缓蚀作用

应用线性极化法和塔菲尔外推法,研究了乌洛托品、硫脲、8-羟基喹啉三种有机缓蚀剂在0．8mol／LNaCl的模拟混凝土孔隙溶液中对R235钢筋的缓蚀效果．研究结果表明,当溶液的pH值为12．95时,8-羟基喹啉、乌洛托品对钢筋具有较好的缓蚀效果,硫脲几乎没有缓蚀效果;pH值降至10．95时,8-羟基喹啉基本失去缓蚀性;乌洛托品在高浓度时仍具有较好的缓蚀效果;硫脲和乌洛托品有协同作用,可以有效降低乌洛托品的用量．还初步探讨了缓蚀的机理．     

稀盐酸溶液中钛在受热和传热条件下的腐蚀行为

用模拟钛加热设备的方法、自腐蚀电位随时间的变化、极化曲线法及Ｘ光电子能谱分析等手段，研究了在稀盐酸溶液中钛在受热和传热条件下腐蚀行为，实验证明了钛的腐蚀行为不仅与被加热的稀盐酸的温度和浓度有关，并且与钛加热设备本身的温度也有密切关系，随着钛设备温度上升，稀盐酸的腐蚀临界浓度和临界温度下降．     

Effects of solution environments under disbonded coatings on the corrosion behaviors of X70 pipeline steel in acidic soils

A rectangle crevice assembly was used to study the effects of cathodic protection (CP) potential, crevice thickness, holiday size, bubbling CO₂, and surface condition on the chemical and electrochemical environment of the local solution under disbonded coatings. It is found that the cathodic protection removes dissolved oxygen from the crevice and thus shifts the solution to a more alkaline state. Furthermore, the potential of the steel reaches the protected potential range. The available protection distance increases with the negative applying potential. The steady potential and pH distribution are easily achieved, but the polarization degree is not satisfied within the thinner crevice. The difference in the solution environment is found to correlate to the holiday size. The smaller the holiday, the smaller the difference is. The presence of CO₂ inhibits the formation of an alkaline environment. It is also found that the rust layer dramatically decreases the polarization rate in the crevice.     

Pitting corrosion resistance of a novel duplex alloy steel in alkali-activated slag extract in the presence of chloride ions

In this study, two types of reinforcing steels (conventional low-carbon steel and a novel duplex alloy steel with Cr and Mo) were exposed to chloride-contaminated extract solutions (ordinary Portland cement (OPC) extract and alkali-activated slag (AAS) extract) to investigate their pitting corrosion resistance. The results confirm that the pitting corrosion resistance of the alloy steel is much higher than that of the low-carbon steel in both extract solutions with various NaCl concentrations. Moreover, for each type of steel, the AAS extract contributes to a higher pitting corrosion resistance compared with the OPC extract in the presence of chloride ions, likely because of the formation of flocculent precipitates on the steel surface.     

347H不锈钢电化学腐蚀行为研究

使用电化学工作站检测热轧态347H不锈钢、固溶态酸洗347H不锈钢和固溶处理态347H不锈钢在3.5wt.%NaCl、5wt.%H₂SO₄和5wt.%NaOH腐蚀介质中的电化学腐蚀行为,绘制极化曲线和电化学阻抗谱研究固溶处理对347H不锈钢电化学腐蚀行为的影响.结果表明:在3.5wt.%NaCl腐蚀介质中,固溶态酸洗347H不锈钢表现出最佳的耐腐蚀性,而固溶处理会降低热轧态347H不锈钢的耐腐蚀性能.在5wt.%H₂SO₄腐蚀介质中,通过1 160 ℃固溶处理2 h,347H不锈钢的耐腐蚀性有所提高.在5wt.%NaOH腐蚀介质中,热轧态347H不锈钢的自腐蚀电流密度和其他状态的347H不锈钢相比要小一个数量级,因此,热轧态347H不锈钢更耐5wt.%NaOH腐蚀介质的腐蚀.     

光照对Q450NQR1耐候钢在干湿交替下腐蚀行为的影响

采用腐蚀质量损失、扫描电子显微镜、X射线衍射仪、线性极化等测试手段,研究无光照、半光照及全光照三种实验条件对Q450NQR1耐候钢在干湿交替条件下腐蚀行为的影响规律.结果表明:光照对实验钢干湿交替腐蚀过程影响显著.实验钢在腐蚀前期(48h)腐蚀速率大小依次为半光照、无光照和全光照,腐蚀中后期(72 ～96h)腐蚀速率由大到小依次为半光照、全光照和无光照.腐蚀宏观形貌有明显差别,无光照时试样腐蚀产物呈淤泥状分布整个表面,有光照条件时腐蚀产物则呈颗粒状分布,但全光照条件时腐蚀产物颗粒更细且孔隙更小.另外,三种条件下腐蚀产物物相组成一致,但含量有所不同.线性极化测试得出96h极化电阻由大到小依次为无光照、全光照和半光照,这一结果与通过腐蚀失重得出的腐蚀速率结果一致.     

醋酸介质中T-403塔不锈钢填料腐蚀机理研究

某化工厂PTA装置氧化单元系统中铁离子含量增高，已影响到氧化反应效果，严重威胁稳定生产，分析认为铁离子主要来自T-403溶剂回收塔316L不锈钢填料的腐蚀．利用扫描电镜、电子探针、金相显微镜等现代物理和化学分析检测手段，观察了从T-403塔取出填料的微观形貌，测试分析了所用填料的主要化学成分及元素分布，对比了未使用和已腐蚀填料的金相显微结构、力学性能变化，研究分析了不锈钢填料的腐蚀机理．实验结果表明：不锈钢填料发生了严重的局部腐蚀，腐蚀形态为晶间腐蚀和小孔腐蚀．填料发生腐蚀后，强度和硬度明显降低．测试分析结果证明，贫铬导致晶间腐蚀，Br以及不锈钢钝化膜局部破损造成蚀孔．原填料质量存在问题，不锈钢填料的含碳量未达到超低碳316L不锈钢的标准．     

The effect of environmental variables on atmospheric corrosion of carbon steel in Shenyang

A study was carried out in order to investigate the effect of contaminants and meteorological variables on the rust layer of carbon steel exposed in Shenyang urban atmosphere. Seven kinds of contaminants and twelve kinds of meteorological parameters were also registered in order to correlate the data with respect to corrosion rate and the stepwise multiple regression analysis was carried out in order to obtain the best regression model. The sum of rainfall time as well as sunshine time and the concentration of H2S could stimulate initial atmospheric corrosion of carbon steel. The initial atmospheric corrosion kinetics of carbon steel was observed to follow the cubic equation. The corrosion products were analyzed by XRD and the transformation of phases in different periods was discussed.     

一种席夫碱在酸性介质中对N80钢的缓蚀机理研究

以苯甲醛、水合肼为原料合成一种席夫碱,研究了其在5%的HCl中的缓蚀性能及缓蚀机理,并计算了相应的热力学数据.研究表明:该席夫碱是以抑制阳极腐蚀过程为主的混合型缓蚀剂,它在N80钢表面的吸附过程是吸热过程,其吸附行为符合Langmuir吸附等温式.     

铜离子和聚乙二醇辛基苯基醚(OP)对钢的缓蚀协同效应

 用失重法研究了在盐酸介质中,金属铜离子(II)和非离子表面活性剂聚乙二醇辛基苯基醚(OP)对钢的缓蚀协同作用,讨论了产生缓蚀协同作用的原因.     

CO2分压对N80钢腐蚀产物膜保护性能的影响

利用高温高压釜对N80钢进行了两种温度、不同CO2分压下的腐蚀实验.测量了腐蚀速率,观察了腐蚀产物膜的宏观形貌及去除腐蚀产物膜后金属基体的表面状态,用扫描电镜(SEM)观察了腐蚀产物膜的微观形貌并测量了膜的厚度,对在不同条件下成膜的N80钢进行了电化学极化曲线与交流阻抗谱(EIS)分析.结果表明:CO2分压升高,腐蚀产物膜保护性能提高,但由于介质的腐蚀性增强,腐蚀速率上升;膜局部缺陷是导致金属基体表面点蚀的主要诱因,CO2分压升高有利于减少65℃时膜表面的局部缺陷;在90℃下腐蚀产物膜的保护性能比65℃下对CO2分压的变化更为敏感.     

非金属夹杂物对弹簧钢局部腐蚀的影响

Certain inclusions in high-strength 60Si2Mn–Cr spring steel result in poor resistance to localized corrosion. In this work, to study the effect of inclusions on the localized corrosion behavior of spring steel, accelerated corrosion tests were performed by immersing spring steel in 3wt% FeCl₃ solution for different times. The results show that severe corrosion occurred in areas of clustered CaS inclusions. Sulfide inclusions containing Ca and Mg induced the strongest localized corrosion susceptibility. For the case of (Ca,Mn,Mg)S inclusions, the ability to induce localized corrosion susceptibility is ranked as follows: MgS > CaS > MnS. Moreover, CaS, (Ca,Mn)S, and (Ca,Mn,Mg)S inclusions were mainly responsible for inducing environmental embrittlement.     

Electrochemical corrosion failure mechanism of M152 steel under a salt-spray environment

The corrosion failure mechanism of M152 was studied using the neutral salt-spray test to better understand the corrosion behavior of 1Cr12Ni3Mo2VN (M152), provide a basis for the optimization of material selection, and prevent the occurrence of failure. Moreover, the mechanism was investigated using the mass loss method, polarization curves, electrochemical impedance spectroscopy (EIS), stereology microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy (EDS). The results show that M152 steel suffers severe corrosion, especially pitting corrosion, in a high-salt-spray environment. In the early stage of the experiment, the color of the corrosion products was mainly orange. The products then gradually evolved into a dense, brown substance, which coincided with a decrease of corrosion rate. Correspondingly, the EIS spectrum of M152 in the late test also exhibited three time constants and presented Warburg impedance at low frequencies.     

Cl-和HCO3-对N80钢阳极电化学行为的协同作用

采用动电位极化曲线和动电位电化学阻抗谱对含不同浓度Cl-和HCO3-溶液体系中N80钢的阳极电化学行为进行了研究.溶液体系中不含Cl-的情况下,HCO3-的浓度超过0.03 mol.L-1时可使N80钢发生钝化.Cl-能极大提高发生钝化的HCO3-浓度临界值,同时对材料表面的钝化膜具有强烈的破坏作用.在阳极区,同等HCO3-浓度下,含Cl-的溶液体系中点蚀电位下降,维钝电位区间变窄,维钝电流密度升高.动电位电化学阻抗谱结果与动电位极化曲线基本对应.等效电路中电器元件与极化电位的关系表明,在含Cl-的溶液体系中N80钢的钝化膜粗糙度与致密性均有所下降,维钝电流密度升高主要由电荷转移电阻的降低所致.     

土壤中宏电池对X70钢腐蚀作用的研究

摘要：利用失重法、电化学阻抗测试技术等方法,研究了X70钢在土壤中的宏电池腐蚀行为。试验结果表明,宏电池粘土中 阳极的腐蚀速率为自然腐蚀速率的307倍。在宏电池阴阳极面积比15∶1情况下,粘土中宏电池阳极的腐蚀速率为阴阳极面积比1∶1时的210倍。随着实验时间的增加,粘土中X70钢自然腐蚀速率逐渐减 小,而宏电池阳极的腐蚀速率一直保持着相当高的腐蚀速率。     

304 L不锈钢焊缝在混凝土模拟孔隙液中的点蚀行为

采用动电位极化曲线、电化学阻抗谱、Mott-Schottky曲线等电化学方法研究了以308 L为焊丝的304 L不锈钢焊接接头在不同氯离子含量的混凝土模拟孔隙液中腐蚀行为和电化学规律。随Cl-增加,304 L不锈钢焊接接头的三个区域(母材、焊缝和热影响区)在混凝土模拟孔隙液中的自腐蚀电位、点蚀电位及电荷转移电阻降低,钝化膜中载流子密度和焊接接头的点蚀坑数量增加。在同浓度的腐蚀溶液中,308 L的焊缝区域耐蚀性最佳,热影响区次之,304 L基体表现出低的电荷转移电阻和高的掺杂浓度使得母材的耐蚀性最差。     

300M超高强度钢电化学性能及应力腐蚀开裂

采用动电位扫描技术和慢应变速率拉伸试验研究了超高强度钢300M在3.5%NaCl溶液中的应力腐蚀行为,并利用扫描电镜观察了不同外加电位下的断口形貌.300M钢在3.5%NaCl溶液中开路电位下的应力腐蚀开裂机制为阳极溶解型,Cl-的存在明显地增加了材料的应力腐蚀开裂敏感性.阳极电位-600 mV下300M钢溶解速率加快,表现出较高的应力腐蚀开裂敏感性,断面收缩率损失由开路电路下的52.6%升高至99.5%,裂纹起源于表面点蚀坑处,应力腐蚀开裂为阳极溶解型机制.阴极电位-800 mV下材料处于阴极保护电位范围,表现出较低的应力腐蚀开裂敏感性,强度和韧度与空气中拉伸的数值相近,开裂机制为阳极溶解和氢致开裂协同作用.在更低电位(低于-950 mV)下,300M钢的应力腐蚀开裂机制为氢致开裂,在氢和拉应力的共同作用下表现出很大的应力腐蚀开裂敏感性.     

碳钢在二氧化碳溶液中腐蚀影响因素的研究

研究了碳钢在二氧化碳饱和溶液中各种因素对腐蚀的影响。研究结果表明腐蚀速率随CO₂压力的升高而增大;温度在60℃时腐蚀速率最大;钙离子的存在减缓了腐蚀;当NaCl质量浓度等于30g/L时,腐蚀速率最大;Mg²⁺和SO_4^2-离子对腐蚀速率影响不大。