可溶盐沉积对碳钢大气腐蚀的影响

采用实验室模拟方法,在温度298 K、相对湿度(85±5)％的条件下,对经Na2SO4、(NH4)2SO4、NH4Cl 和NaCl沉积后的A3钢在净化空气中的大气腐蚀行为进行了研究.腐蚀动力学曲线表明,尽管沉积了不同的可溶盐,但随暴露时间的增加,A3钢单位面积的腐蚀质量损失均服从Δm/A=K•tb公式. 不同盐对A3钢的腐蚀失重影响有所不同. 用FTIR、SEM以及XRD分析研究了不同盐沉积的试样腐蚀4周后的组成和形貌,发现腐蚀主要沿着沉积了可溶盐的区域进行,并随着腐蚀时间的延长,生成不同的腐蚀产物,这些腐蚀产物使A3钢最初的快速腐蚀现象有所减缓.     

A3钢在氧化亚铁硫杆菌、链霉菌及其混合菌体系中的腐蚀行为

采用电化学方法和表面分析技术研究了A3钢在链霉菌(Stremptomyces)和氧化亚铁硫杆菌(Thiobacillus fer-rooxidans,T.f)单独及共同作用下的腐蚀行为.结果表明,试样在不同的含菌腐蚀体系中浸泡7d后,表面生成了不均匀的生物膜层,并表现出各不相同的形貌特征;A3钢在氧化亚铁硫杆菌和链霉菌单种菌作用下发生了局部腐蚀,而混合菌体系中的试样发生均匀腐蚀;混合菌体系中A3钢的腐蚀失重速率介于两种菌单独存在时的腐蚀失重速率之间;试样浸泡14d后的电化学阻抗谱(EIS)测试结果表明,A3钢电极在氧化亚铁硫杆菌-链霉菌混合菌体系中的阻抗值介于两种单菌腐蚀体系之间.以上研究结果表明,A3钢在链霉菌体系中腐蚀最重,混合菌体系其次,氧化亚铁硫杆菌体系中腐蚀最轻.     

A3钢在链霉菌和诺卡氏菌共同作用下的腐蚀行为

采用腐蚀失重法、电化学交流阻抗法(EIS)和表面分析技术研究了A3钢在链霉菌(Stremptomyces)和诺卡氏菌(Nocardia sp)共同作用下的腐蚀行为. 结果表明, 与单种菌相比, 混合菌作用下试样表面的腐蚀倾向增大, 阻抗值降低, 腐蚀电流密度增加. 浸泡21天后, 混合菌溶液中A3钢的腐蚀失重速率大于两种微生物单独存在时的腐蚀失重速率之和. 扫描电子显微镜(SEM)分析结果表明, 混合菌溶液中A3钢表面发生了严重的局部腐蚀, 在链霉菌和诺卡氏菌的共同作用下, A3钢的腐蚀程度加剧.     

A3钢在氧化硫硫杆菌作用下的腐蚀行为

采用表面分析技术、失重法和电化学测试研究了A3钢在氧化硫硫杆菌(T.t)作用下的腐蚀行为. 扫描电子显微镜(SEM)分析结果表明, 与无菌体系相比, 氧化硫硫杆菌会在A3钢表面形成致密的生物膜和腐蚀产物膜. 去除膜层后, 无菌体系中的试样出现点蚀, 氧化硫硫杆菌体系中试样呈现为均匀腐蚀. 浸泡三周后, 氧化硫硫杆菌体系中A3钢的腐蚀失重远小于无菌体系. 电化学交流阻抗谱(EIS)测试结果显示, 在浸泡10 d后, 氧化硫硫杆菌中的电极表面只存在两个时间常数, 这表明氧化硫硫杆菌会在试样表面形成致密且附着力非常强的产物膜层, 有效地阻碍了腐蚀介质对基体的侵蚀. 极化曲线结果表明, 浸泡20 d后, 氧化硫硫杆菌的存在使得金属具有较小的自腐蚀电流密度.     

A3钢在缓蚀颜料提取液中的EIS研究

应用EIS研究了A3钢在不同 pH值的磷酸锌或三聚磷酸铝 3.5 %NaCl提取液中的腐蚀行为 .结果显示 ,相同条件下 ,A3钢的电阻值随溶液 pH值增加而增加 ,电容值则相反 .在磷酸锌3.5 %NaCl提取液中 ,因磷酸锌的溶解度太小 ,没有足够的量对金属基底A3钢进行有效的保护 .在 pH值为 6的三聚磷酸铝 3.5 %NaCl提取液中 ,A3钢表现出较明显的缓蚀现象 ,可能是因为三聚磷酸根离子与腐蚀产物Fe2 + 、Fe3+ 络合并在钢表面形成了一层致密的保护膜 ,从而有效地阻止了腐蚀介质的进一步入侵 .防蚀颜料的溶解度大小是决定它的缓蚀性能优劣的重要因素之一     

稀土含量对1OPCuRE耐候钢耐蚀性能的影响

通过浸渍干湿循环加速腐蚀试验,采用失重法测量年蚀率,电化学方法测试极化电阻和阳极极化曲线.研究了不同稀土含量的10PCuRE耐候钢与A3钢的耐候性能,并加以分析.结果表明:10PCuRE耐候钢性能明显优于A3钢.耐候钢和A3钢经室内加速腐蚀后表面呈不同状态.耐候钢表面生成均匀美观的黄褐色锈层,显微镜下可观察到细小的球状氧化物颗粒均匀分布,而A3钢表面锈层粗糙有瘤状氧化物突起,锈层呈黑色与黄褐色不规则分布.比较样品的腐蚀率等参数可知,在较纯净的钢中含有一定量的稀土即可大大提高耐候钢的耐蚀性能.     

A3钢在芽孢杆菌作用下的腐蚀行为

采用表面分析技术、失重法和电化学测试技术研究了A3钢在芽孢杆菌(Bacillus)作用下的腐蚀行为.扫描电子显微镜(SEM)分析结果表明,浸泡7d时,芽孢杆菌会在A3钢表面形成致密的生物膜,有效阻隔了溶液对基体的腐蚀,抑制了腐蚀过程.电化学交流阻抗测试结果显示,含菌体系中的试样表面经历了2个时间常数→3个时间常数→2个时间常数的变化过程.失重法和极化曲线测试结果表明,芽孢杆菌的细菌活性对生物膜的保护作用有着决定性的影响,当微生物活性下降,生物膜的保护能力也会大幅降低.     

含O2高温高压CO2环境中3Cr钢腐蚀产物膜特征

采用高温高压反应釜分别开展3Cr钢在CO2和O2共存、单独CO2和单独O2三种气体条件下的腐蚀实验,利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能量色散X射线能谱(EDS)和电化学方法研究了3Cr钢在高温高压含有O2的CO2环境中的腐蚀产物膜特征.结果表明,在含有O2的CO2的条件下,3Cr钢表面腐蚀产物膜疏松多孔,主要成分为FeCO3、Fe3O4和Fe2O3,腐蚀产物中未见明显Cr元素富集,3Cr钢表现出点蚀的腐蚀形态.3Cr钢在高温高压含O2的CO2腐蚀条件下内外膜层电阻(Rf1、Rf2)和电荷传递电阻Rt均比仅含有CO2腐蚀环境的低,双电层电容(Cdl)和内外膜层电容(Cf1、Cf2)均比仅含有CO2腐蚀环境的高.含有O2的CO2条件下,其保护性显著低于单一CO2条件下形成的腐蚀产物膜.提出了在含O2的CO2气体条件下,3Cr钢表面存在由多种物质组成的腐蚀产物,这导致腐蚀产物疏松多孔,不会形成单一CO2条件下存在的显著提高腐蚀产物膜保护性的Cr(OH)3层,从而促进了3Cr钢的析氢腐蚀和酸性介质中的吸氧腐蚀的机理.     

氧化亚铁硫杆菌作用下A3钢的腐蚀行为

采用微生物学方法、电化学方法和表面分析技术研究了A3钢在氧化亚铁硫杆菌中的腐蚀特征和生物膜形貌, 分析了微生物的存在对A3钢电化学行为的影响. 极化曲线测试结果表明, 细菌的存在使浸泡20天后A3钢电极的自腐蚀电位升高, 腐蚀电流密度增大. 原子力显微镜测试结果表明, 浸泡7天的A3钢表面生物膜分布不均匀, 从而引发点蚀萌生. 由于细菌的代谢作用以及A3钢表面腐蚀产物与生物膜的特殊形貌特征, 浸泡在菌液中7天后的A3钢表面有点蚀出现; 随着时间的延长, A3钢表面的点蚀坑深度增大且数量增多, 氧化亚铁硫杆菌的存在使A3钢的局部腐蚀程度加剧.     

生物膜和腐蚀产物膜对A3钢的腐蚀作用研究

应用电化学方法和表面分析技术(AFM和SEM)研究硫酸盐还原菌(SRBB)(生物环境)及其腐蚀产物(非生物环境)对A3钢腐蚀行为的影响以及A3钢在两种不同环境下的腐蚀特征.结果表明:于不同时期生成的微生物膜和腐蚀产物膜,对材料的腐蚀起着不同的作用.生成的生物膜越厚越容易剥落,而不均匀的微生物膜将引起材料的局部腐蚀.在非生物环境中生成的腐蚀产物膜比在生物环境中生成的膜更加紧密地黏附于金属的表面.     

Crystallization of aqueous inorganic-malonic acid particles: nucleation rates, dependence on size, and dependence on the ammonium-to-sulfate ratio

Using an electrodynamic balance, we determined the relative humidity (RH) at which aqueous inorganic-malonic acid particles crystallized, with ammonium sulfate ((NH(4))(2)SO(4)), letovicite ((NH(4))(3)H(SO(4))(2)), or ammonium bisulfate (NH(4)HSO(4)) as the inorganic component. The results for (NH(4))(2)SO(4)-malonic acid particles and (NH(4))(3)H(SO(4))(2)-malonic acid particles show that malonic acid decreases the crystallization RH of the inorganic particles by less than 7% RH when the dry malonic acid mole fraction is less than 0.25. At a dry malonic acid mole fraction of about 0.5, the presence of malonic acid can decrease the crystallization RH of the inorganic particles by up to 35% RH. For the NH(4)HSO(4)-malonic acid particles, the presence of malonic acid does not significantly modify the crystallization RH of the inorganic particles for the entire range of dry malonic acid mole fractions studied; in all cases, either the particles did not crystallize or the crystallization RH was close to 0% RH. Size dependent measurements show that the crystallization RH of aqueous (NH(4))(2)SO(4) particles is not a strong function of particle volume. However, for aqueous (NH(4))(2)SO(4)-malonic acid particles (with dry malonic acid mole fraction = 0.36), the crystallization RH is a stronger function of particle volume, with the crystallization RH decreasing by 6 +/- 3% RH when the particle volume decreases by an order of magnitude. To our knowledge, these are the first size dependent measurements of the crystallization RH of atmospherically relevant inorganic-organic particles. These results suggest that for certain organic mole fractions the particle size and observation time need to be considered when extrapolating laboratory crystallization results to atmospheric scenarios. For aqueous (NH(4))(2)SO(4) particles, the homogeneous nucleation rate data are a strong function of RH, but for aqueous (NH(4))(2)SO(4)-malonic acid particles (with dry organic mole fraction = 0.36), the rates are not as dependent on RH. The homogeneous nucleation rates for aqueous (NH(4))(2)SO(4) particles were parametrized using classical nucleation theory, and from this analysis we determined that the interfacial surface tension between the crystalline ammonium sulfate critical nucleus and an aqueous ammonium sulfate solution is between 0.053 and 0.070 J m(-2).     

Crystallization pathways of sulfate-nitrate-ammonium aerosol particles

Crystallization experiments are conducted for aerosol particles composed of aqueous mixtures of (NH(4))(2)SO(4)(aq) and NH(4)NO(3)(aq), (NH(4))(2)SO(4)(aq) and NH(4)HSO(4)(aq), and NH(4)NO(3)(aq) and NH(4)HSO(4)(aq). Depending on the aqueous composition, crystals of (NH(4))(2)SO(4)(s), (NH(4))(3)H(SO(4))(2)(s), NH(4)HSO(4)(s), NH(4)NO(3)(s), 2NH(4)NO(3) x (NH(4))(2)SO(4)(s), and 3NH(4)NO(3) x (NH(4))(2)SO(4)(s) are formed. Although particles of NH(4)NO(3)(aq) and NH(4)HSO(4)(aq) do not crystallize even at 1% relative humidity, additions of 0.05 mol fraction SO(4)(2-)(aq) or NO(3)(-)(aq) ions promote crystallization, respectively. 2NH(4)NO(3) x (NH(4))(2)SO(4)(s) and (NH(4))(3)H(SO(4))(2)(s) appear to serve as good heterogeneous nuclei for NH(4)NO(3)(s) and NH(4)HSO(4)(s), respectively. 2NH(4)NO(3) x (NH(4))(2)SO(4)(s) crystallizes over a greater range of aqueous compositions than 3NH(4)NO(3) x (NH(4))(2)SO(4)(s). An infrared aerosol spectrum is provided for each solid based upon a linear decomposition analysis of the recorded spectra. Small nonzero residuals occur in the analysis because aerosol spectra depend on particle morphology, which changes slightly across the range of compositions studied. In addition, several of the mixed compositions crystallize with residual aqueous water of up to 5% particle mass. We attribute this water content to enclosed water pockets. The results provide further insights into the nonlinear crystallization pathways of sulfate-nitrate-ammonium aerosol particles.     

聚吡咯/聚苯胺复合型导电聚合物防腐蚀性能

采用循环伏安法,在含吡咯和苯胺的0.3 mol/L草酸水溶液中制备了聚吡咯/聚苯胺(PPy/Pani)的复合型导电聚合膜。采用红外光谱、极化曲线、自腐蚀电位-时间曲线、扫描电子显微镜和电化学阻抗谱研究了共聚膜的防腐蚀性能。结果表明,在1 mol/L H2SO4中,PPy、Pani与不锈钢基体发生氧化还原反应,促进不锈钢表面发生钝化;当苯胺与吡咯浓度比为1∶3时,制备得到的复合型导电聚合膜所保护的不锈钢自腐蚀电流最小,自腐蚀电位最高,保护时间最长。PPy、Pani及其共聚膜在3.5%NaCl溶液中电化学阻抗谱表明,所制备的PPy、Pani及其共聚物膜与不锈钢基体发生氧化还原反应,使其表面钝化;当Cl-到达不锈钢表面时,破坏钝化膜导致不锈钢腐蚀。     

吗啡啉功能化酸性离子液体的合成、表征及其催化酯化性能

制备和表征了三种新型质子酸离子液体: 吗啡啉硫酸氢盐([Hnhm]HSO4)、4-甲基吗啡啉硫酸氢盐 ([Hnmm]HSO4)和SO3H-功能化的4-(3-磺丙基)吗啡啉硫酸氢盐([C3SO3Hnhm]HSO4). 以氯乙酸(CAA)和乙醇合成氯乙酸乙酯的酯化反应考察了它们的酸性和催化活性, 并与1-(3-磺酸基)丙基-3-甲基咪唑硫酸氢盐、1-(3-磺丙基)吡啶硫酸氢盐、1-(3-磺丙基)-2-吡咯烷酮硫酸氢盐等三种具有不同氮杂环的SO3H-功能化酸性离子液体以及浓硫酸相对照. 结果表明, 上述SO3H-功能化离子液体对酯化反应的催化性能比非SO3H-功能化的[Hnhm]HSO4和[Hnmm]HSO4都高, 等同甚至优于浓硫酸. 当反应条件为: n(EtOH)∶n(CAA)∶n([C3SO3Hnhm]HSO4)＝1.3∶1∶0.2, 反应温度80 ℃, 反应时间3 h, 酯收率可达93.4%. 而且离子液体经真空干燥重复使用9次, 催化活性仍无明显下降. 以[C3SO3Hnhm]HSO4催化乙酸和不同醇的酯化反应获得较高的酯收率和选择性, 离子液体跟酯产物均能自动分相. 还考察了SO3H-功能化酸性离子液体对奥氏体316不锈钢的腐蚀性. 尽管SO3H-功能化离子液体与硫酸的酸性相近, 但对钢试样的腐蚀率不到硫酸的1/3.     

O,O′-二(4-甲苯基)二硫代磷酸-N,N-二乙铵的晶体结构、热稳定性及缓蚀性

合成了O,O′-二(4-甲苯基)二硫代磷酸N,N-二乙铵（[Et2NH2][(4-MeC6H4O)2PS2],NOP）,采用元素分析、红外光谱、核磁共振谱和单晶X射线衍射测试技术对其结构进行了表征,同时研究了NOP的热稳定性和缓蚀性。 NOP晶体属单斜晶系,P21/n空间群,晶胞参数为：a=1.424 1(3) nm,b=2.008 7(4) nm,c=1.436 6(3) nm,V=3.959 9(15) nm3,Dc=1.286 Mg/m3,Z=8,F(000)=1.632,μ(MoKα)=0.360 mm-1,S=1.001,(Δ/σ)max=0.001,R1=0.077 6,wR2=0.174 9(I＞2σ(I))。 NOP的不对称结构单元中包括2个独立的子单元,2个子单元之间通过N-H…S氢键形成了一维链结构。 在H2SO4溶液中,NOP能有效抑制Q235钢的腐蚀,是一种抑制阳极反应为主的高效混合型缓蚀剂;NOP在Q235钢表面的吸附符合Langmuir吸附等温式,属自发进行的物理和化学吸附。 CCDC813309     

Linear solvation energy parameters for model tropospheric aerosol surfaces

Excited-state absorption spectra for several coumarin derivatives adsorbed to aerosol particles provide linear solvation energy (LSE) relationships for the aerosol surfaces. This study focuses on NaCl and (NH4)2SO(4) particles as models for tropospheric aerosol. We investigate several others, including NH(4)Cl, NaBr, KI, Na(2)SO(4), NaNO(3), Al(2)O3, and CaCO(3), to establish trends and understand the factors that control polarity for surfaces. The Kamlet-Taft dipolarity/polarizability parameter, pi*, for these particles ranges from 0.73 to 1.69. The values are high compared to most homogeneous molecular solvents and are attributable to ion-dipole forces, especially at defect sites. We also find that the smaller values of pi* (1.01 for (NH4)2SO(4) and 0.73 for NH(4)Cl) correlate with appreciable hydrogen bond donor acidity in the surface (alpha = 0.23 and 1.06, respectively). Strong hydrogen bonds with the surface lead to a drop in overall polarity either by making interaction with very polar defect sites less likely or orienting the probe molecule away from the surface. Adsorbed water layers mainly alter the alpha value of the surface, but can have indirect effects on pi* by changing the interaction of the adsorbed molecule with the surface.     

XPS depth profile study of porous zirconia films deposited on stainless steel by spray pyrolysis: the problem of substrate corrosion

Zirconia (ZrO₂) films of tissue‐like structure and narrow pore size distribution have been deposited by spray pyrolysis using aqueous zirconyl chloride octahydrate (ZrOCl₂·8H₂O) precursor solutions. Stainless‐steel sheets, protected or unprotected by a ZnO barrier layer, have been used as the substrate material held at 473 K. The ZnO barrier layers have been deposited on the stainless steel held at 523 K by spray pyrolysis using a zinc acetate precursor. Their property of corrosion protection to stainless steel has been proved by electrochemical polarization measurements in 0.5 M NaCl solution. A complementary study of XPS (depth profiling, mapping) and x‐ray diffraction has shown that the unprotected steel substrates were corroded during ZrO₂ film post‐annealing in air at T ≥ 773 K, whereas steel substrates protected with a compact barrier layer of crystalline ZnO before ZrO₂ film deposition did not show surface corrosion even after annealing up to 997 K. Copyright © 2004 John Wiley & Sons, Ltd.     

Investigation of Glass-Like Sol-Gel Coatings for Corrosion Protection of Stainless Steel Against Liquid and Gaseous Attack

Glass-like sol-gel coatings have been investigated as corrosion protective coatings on stainless steel. Magnesium- and borosilicate coatings with thickness of about 100–700 nm and methyl-modified SiO2 coatings with a thickness of about 2 m were deposited on stainless steel plates by dip-coating. The coatings were densified between 400°C and 500°C in different atmospheres (N2, air) for 1 h. The corrosion protection against gaseous attack was investigated by accelerated corrosion tests, at 800°C in air for 1 h. A corrosion protection factor was calculated from the relation Fe/Fe2O3, determined by XRD on the surface of coated and uncoated samples. Methyl-modified SiO2 coatings showed a protection factor, which was 2 orders of magnitude higher than for the other coatings. Electrochemical investigations were performed on samples submerged in a NaCl solution for 200 h. The corrosion propagation, polarization resistance and impedance vector were measured. For accelerated corrosion tests, polarization intensity curves were determined for high potentials of up to 1 V. Again excellent results were obtained for the methyl-modified SiO2 coatings, which remained passive for 200 h. Results of the salt spray corrosion test, however, showed no corrosion protection by the sol-gel coatings. After 2000 h in the salt spray chamber the steel was corroded and the coatings peeled off. It is concluded that for the further development of these coatings an improved interfacial passivation will be required.     

Bond energies and structures of ammonia-sulfuric acid positive cluster ions

New particle formation in the atmosphere is initiated by nucleation of gas-phase species. The small molecular clusters that act as seeds for new particles are stabilized by the incorporation of an ion. Ion-induced nucleation of molecular cluster ions containing sulfuric acid generates new particles in the background troposphere. The addition of a proton-accepting species to sulfuric acid cluster ions can further stabilize them and may promote nucleation under a wider range of conditions. To understand and accurately predict atmospheric nucleation, the stabilities of each molecular cluster within a chemical family must be known. We present the first comprehensive measurements of the ammonia-sulfuric acid positive ion cluster system NH(4)(+)(NH(3))(n)(H(2)SO(4))(s). Enthalpies and entropies of individual growth steps within this system were measured using either an ion flow reactor-mass spectrometer system under equilibrium conditions or by thermal decomposition of clusters in an ion trap mass spectrometer. Low level ab initio structural calculations provided inputs to a master equation model to determine bond energies from thermal decomposition measurements. Optimized ab initio structures for clusters up through n = 3, s = 3 are reported. Upon addition of ammonia and sulfuric acid pairs, internal proton transfer generates multiple NH(4)(+) and HSO(4)(-) ions within the clusters. These multiple-ion structures are up to 50 kcal mol(-1) more stable than corresponding isomers that retain neutral NH(3) and H(2)SO(4) species. The lowest energy n = s clusters are composed entirely of ions. The addition of acid-base pairs to the core NH(4)(+) ion generates nanocrystals that begin to resemble the ammonium bisulfate bulk crystal starting with the smallest n = s cluster, NH(4)(+)(NH(3))(1)(H(2)SO(4))(1). In the absence of water, this cluster ion system nucleates spontaneously for conditions that encompass most of the free troposphere.