Azole derivatives embedded in montmorillonite clay nanocarriers as corrosion inhibitors of mild steel

Azole derivatives such as 2-mercaptobenzothiazole(MBT) and 2-mercaptobenzimidazole(MBI) were introduced as corrosion inhibitors into the interlayer space of sodium montmorillonite clay(Na+-MMT). The corrosion protection behavior of mild steel in solutions containing MBT, MBI, MMT + MBT, MMT + MBI, Na~+-MMT, and NaCl(3.5 wt%) was evaluated using polarization and electrochemical impedance spectroscopy(EIS). Also, the release of penetrated species into the medium from the clay nanocarriers was evaluated using ultraviolet-visible(UV-Vis) spectroscopy. Small-angle X-ray scattering(SAXS) confirmed the insertion of MBT and MBI into the inner space of the clay layers and the interaction between two organic and inorganic phases. Scanning electron microscopy(SEM) was used to assess the morphology of the surface of the steel samples after the samples had been immersed for 24 h in the extraction solution. The corrosion protection in the solutions with clay nanocarriers containing MBT and MBI was better than that in solutions without MMT. The UV-Vis results showed that the release of MBI species from Na+-MMT nanocarriers in neutral pH was far lower than that of MBT species.     

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。     

纳米金属Cr在酸性介质中腐蚀电化学行为

为探究纳米材料的腐蚀机理,采用机械合金化通过热压制备了纳米金属Cr,并与常规尺寸金属Cr对比研究了其在酸性介质中的腐蚀性能.结果表明:当晶粒尺寸细化到纳米级后,金属Cr腐蚀电流密度增大,耐蚀性能下降;随着酸度的增加,常规尺寸和纳米尺寸金属Cr腐蚀电流密度加大,耐蚀性能下降.两种尺寸金属Cr在中性Na2SO4介质中均出现钝化现象,但常规尺寸金属Cr的钝化区间较宽;常规尺寸金属Cr在加入H+后,钝化减弱,而纳米尺寸金属Cr在加入H+后,钝化现象消失;两种尺寸Cr的交流阻抗谱均呈单容抗弧特征,对纳米材料的应用具有重要意义.     

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。     

在侵略性介质中植物提取物基绿色缓蚀剂的研究进展

在侵略性介质中,金属如碳钢、铜、铝等的腐蚀不可避免并可能造成严重后果,因此防护金属腐蚀非常必要且具有重要意义。与化学合成的有机缓蚀剂相比较,植物提取物基缓蚀剂具有许多独特优点,例如高效率、低成本、可再生与可持续,且符合低碳与绿色化工要求,有利于实现碳达峰与碳中和目标,得到人们极大关注。由于含有许多杂原子基团,植物提取物易与金属发生物理或化学作用形成吸附膜,进而阻碍侵略性物种与金属表面的直接接触,从而阻滞或抑制金属表面的电化学反应,实现在多种侵略性介质中对金属的腐蚀防护,阻止金属溶解。本文重点综述了近二十年植物提取物作为在侵略性介质中抗金属腐蚀材料的研究进展,特别是关于抑制钢腐蚀的研究进展,探讨了其作为有机绿色缓蚀剂的科学基础与应用潜能,并展望了本领域未来研究重点与研究目标,为人们利用探索天然产物基的有机缓蚀剂提供一定指导作用。     

水和氯离子含量对碳钢接地网在酸性土壤中腐蚀行为的影响

以某变电站的土壤作为研究对象,通过电化学测试,研究了含水量和氯离子含量对碳钢接地网在该土壤中的腐蚀行为的影响.研究结果表明,随着含水量的增加,碳钢接地网的腐蚀速率先增大后减小.当含水量在20%~30%时,腐蚀速率达到最大;当土壤中氯离子含量在0.2%~0.5%之间时,碳钢接地网的腐蚀速率达到最大;经过28 d后,在氯离子含量为0.5%的土壤中,其腐蚀电流密度高达167.4μA/cm2.     

Novel renin inhibitors containing the amino acid statine

The proteolytic enzyme renin (EC3.4.99.19) cleaves the protein substrate angiotensinogen to yield angiotensin I, the decapeptide substrate transformed by converting enzyme into the pressor substance angiotensin II. Although the contribution of this pathway to the maintenance of normal blood pressure is unclear, it seems to be a major factor in various hypertensive states. Important progress in the control of hypertension has been achieved by development of the potent inhibitors SQ-14,225 (captopril) and MK-421 (enalapril maleate), which block the generation of angiotensin II by the inhibition of angiotensin converting enzyme. An attractive alternative to the inhibition of converting enzyme would be the blockade of the preceding step in the cascade, the renin reaction. We report here new highly potent (IC50 = 10(-9)-10(-8) M) competitive inhibitors of renin in which statine, (3S,4S)-4-amino-3-hydroxy-6-methylheptanoic acid, is incorporated into analogues of the pig renin substrate (Fig. 1).     

pH值对Q235钢在模拟酸性土壤中腐蚀行为的影响

通过腐蚀失重计算、扫描电镜、X射线衍射方法、极化曲线分析等手段,研究了pH值对Q235钢在模拟酸性土壤中腐蚀行为的影响.在模拟酸性土壤环境中,Q235钢的腐蚀速率随土壤pH值升高而降低,经360 h腐蚀后,在pH值为4.0、4.5和5.1的土壤中试样的腐蚀速率分别为0.68、0.48和0.42 mm·a-1.随土壤pH值升高,Q235钢锈层更为致密,其表面蚀坑由窄深型发展变为宽浅型发展.腐蚀产物均为SiO2、α-FeOOH、γ-FeOOH、Fe2 O3及 Fe3 O4,随土壤 pH值升高,腐蚀产物中α-FeOOH/γ-FeOOH质量比升高.极化曲线分析表明,随土壤pH值升高,Q235钢腐蚀电位升高,自腐蚀电流密度降低,试样腐蚀速率减小.     

用丝束电极研究NaNO2对钢铁防护性能的影响

采用丝束电极多电极电化学法研究钢铁在不同浓度的NaCl溶液中的电位变化,并分析NaN02的加入对体系电位的影响和NaN02对钢铁的防护作用。研究结果表明：钢铁在NaCl溶液中的电位分布在一定的电位区间,各丝电极的电位存在差异,各区域金属的腐蚀不均匀;随着溶液中NaCl含量从1％增大至5％,丝束电极的电极电位平均值从—0．43V变为-0．54v,电极电位负移,金属腐蚀倾向增大：由于NaNO2和钢铁电极表面的腐蚀产物Fe^2＋的相互作用并生成保护性的薄膜,在NaCl溶液中加入NaNO2将使体系电极电位明显正移：加入NaNO2后各丝电极电位的分布是随机的、不均匀的,且电位分布区间增大,表明所形成的保护性薄膜不均匀。     

Effect of deteriorated microstructures on stress corrosion cracking of X70 pipeline steel in acidic soil environment

In order to investigate stress corrosion cracking (SCC) of X70 pipeline steel and its weld joint area in acidic soil environment in China, two simulating methods were used:one was to obtain bad microstructures in heat affected zone by annealing at 1300℃ for 10 min and then, quenching in water; the other was to get different simulating solutions of acidic soil in Yingtan in south-east China. The SCC susceptibilities of X70 pipeline steel before and after quenching in the simulating solutions were analyzed using slow stain rate test (SSRT) and potentiodynamic polarization technique to investigate the SCC electrochemical mechanism of different microstructures further. The results show that SCC appears in the original microstructure and the quenched microstructure as the polarization potential decreases. Hydrogen revolution accelerates SCC of the two tested materials within the range of -850 mV to -1200 mV vs. SCE. Microstructural hardening and grain coarsening also increase SCC. The SCC mechanisms are different, anodic dissolution is the key of causing SCC as the polarization potential is higher than the null current potential, and hydrogen embrittlement will play a more important role to SCC as the polarization potential lower than the null current potential.     

Electrochemical and analytical characterization of three corrosion inhibitors of steel in simulated concrete pore solutions

Corrosion inhibitors for steel, such as sodium phosphate (Na₃PO₄), sodium nitrite (NaNO₂), and benzotriazole (BTA), in simulated concrete pore solutions (saturated Ca(OH)₂) were investigated. Corrosion behaviors of steel in different solutions were studied by means of corrosion potential (E_corr), linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP). A field emission scanning electron microscope (FESEM) equipped with energy dispersive X-ray analysis (EDXA) was used for observing the microstructures and morphology of corrosion products of steel. The results indicate that, compared with the commonly used nitrite-based inhibitors, Na₃PO₄ is not a good inhibitor, while BTA may be a potentially effective inhibitor to prevent steel from corrosion in simulated concrete pore solutions.     

Inhibitive effect of Xylopia ferruginea 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.     

植酸自组装膜对Q235钢在氯化钠溶液中的缓蚀作用

从植物中提取的植酸作金属缓蚀剂对环境保护具有重要意义.采用失重法、扫描电子显微镜和X射线能谱研究了植酸对Q235钢在NaCl溶液中的缓蚀行为以及影响因素.失重实验结果表明,不同pH值植酸对Q235钢的缓蚀效果明显不同,在酸性条件下植酸加速Q235钢的腐蚀,在中性及碱性条件下,植酸对Q235钢的腐蚀具有明显的抑制作用.中性或碱性条件下,NaCl溶液中植酸对Q235钢缓蚀效率随植酸浓度的增加而增加,植酸浓度达0.5%以上时,缓蚀效率高达90%以上.扫描电镜结果表明,植酸处理后的Q235钢表面生成膜在不同pH下明显不同,碱性条件下的生成膜明显好于酸性条件下的生成膜.     

用灰色关联分析法研究气井腐蚀的影响因素

依据灰色关联分析的原理,编制了计算机程序,并分析了某气田11口气井腐蚀的主要影响因素。结果表明,流速、CO₂分压、产出水中HCO₃^-离子含量等因素对腐蚀有显著的影响,并探讨了这些因素对腐蚀的具体影响。腐蚀速度vc的对数与流速v以及二氧化碳分压pCO₂的对数之间分别存在着线性关系,HCO₃^-离子对腐蚀有促进作用。     

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.     

过期药乙酰螺旋霉素在醋酸介质中对Q235钢腐蚀行为的影响

随着人们环保意识的加强,绿色新型缓蚀剂的研究成为了人们关注的热点.利用电化学方法以及扫描电子显微镜和傅立叶变换红外光谱等电化学技术研究了不同浓度的过期药乙酰螺旋霉素对醋酸介质中Q235钢的缓蚀作用,讨论了产生缓蚀作用的原因和机理.实验结果表明:乙酰螺旋霉素在醋酸介质中对Q235钢的腐蚀具有良好的抑制作用,且缓蚀效果随着乙酰螺旋霉素浓度的增加而增大;乙酰螺旋霉素的吸附行为是一种物理吸附.     

HCl介质中双子季铵盐表面活性剂对碳钢的缓蚀性能

采用质量损失法和电化学方法,研究羟基丙撑双(十二烷基二甲基氯化铵)(HPB)双子型季铵盐表面活性剂在40℃1.0 mol/L HCl、KCl、NaCl和HCl复配缓蚀介质中对碳钢的缓蚀性能。结果表明:HPB是一种性能优异的缓蚀剂,随着浓度的增大,其缓蚀效率逐渐增大,在质量浓度为50 mg/L时,缓蚀效率能达到98%。通过对吸附等温式的探讨,计算出其吸附自由能为-14.64 kJ/mol,推断出HPB在碳钢表面的吸附行为主要为物理吸附。电化学方法的测试结果表明,HPB是一种以抑制阴极反应为主的混合型缓蚀剂。     

氨基酸类有机物在硫酸介质中对钢的缓蚀作用

 用失重法研究了各种氨基酸在硫酸溶液中对钢的缓蚀作用.实验表明,L-半胱氨酸和DL-类半胱氨酸硫内酯盐酸盐对钢有较好的缓蚀作用.应用Langmuir吸附方程讨论了产生缓蚀作用的原因.     

Ni-Cr-Mo-Cu合金介质腐蚀和电化学腐蚀的性能

在Cr、Mo成分一定的情况下,通过改变Cu的质量分数(1%～5%),研究新型Ni-Cr-Mo-Cu高镍耐蚀合金在氧化性介质、还原性介质、氧化-还原性介质和质量分数6%的FeCl3中的耐蚀性能及其在H2SO4、HCl和FeCl3中的电化学行为.实验结果表明,w(Cu)=1%～5%的Ni-Cr-Mo-Cu合金具有优良的耐介质腐蚀、电化学腐蚀性能,在质量分数80%的H2SO4中钝化明显,在质量分数30%的HCl中自腐蚀电流低,在质量分数6%的FeCl3中有钝化区且未发生点蚀.4种实验材料中w(Cu)=3%的合金综合耐蚀性能最好,在质量分数80%的 H2SO4中有更宽的钝化平台和更低的维钝电流.