环氧树脂对混凝土中钢筋抗腐蚀性行为的电化学研究

用4×4阵列丝束电极模拟研究了混凝土中钢筋的腐蚀,将钢筋混凝土做不同的涂层处理：空白、铁丝表面涂抹树脂、混凝土表面涂抹树脂．通过测量铁丝的自腐蚀电位,研究不同涂层方式对混凝土防腐方面的影响．实验结果表明：只在混凝土表面涂抹树脂是最好的保护方式,它可以使钢筋的腐蚀电位一直处于钝化范围内．从而保证了钝化膜的完整性．这一结果对防止沿海地区和冰雪融化剂的氯离子对混凝土的破坏作用有意义,同时可应用于有杂散电流作用的混凝土结构物的防腐蚀．     

应用于地铁杂散电流腐蚀测量的硫酸铜电极实验研究

模拟地铁的实际工况，使用长效铜／硫酸铜电极作为测量混凝土钢筋极化电位的参考电极，检验长效铜／硫酸铜电极的稳定性、有杂散电流扰动时混凝土钢筋极化电位的变化情况以及参考电极安装位置的不同对极化电位测量的影响，同时根据广州地铁一号线杂散电流监测系统记录的数据，分析长效铜／硫酸铜电极的工作情况．实验证明，长效铜／硫酸铜电极可以在地铁的混凝土结构中用于测量埋地金属结构的杂散电流腐蚀．     

20#钢在油田采出液中的腐蚀行为研究

采用腐蚀失重法、丝束电极技术和电化学测量技术研究了20#钢在油田采出液中的腐蚀行为。结果表明,在实验周期内可将腐蚀发展过程分为腐蚀初期、腐蚀发展期和腐蚀稳定期,腐蚀初期对应腐蚀情况最为严重;金属同一位置随实验时间延长发生阴阳极极性反转现象,并且随着温度升高,反转周期变短;通过对腐蚀金属整体和局部进行电化学测量研究发现,不同温度、不同位置腐蚀发生类型有所差别。     

X100管线钢在酸性土壤模拟溶液中的缝隙腐蚀研究

本文采用矩形缝隙模拟构型研究X100管线钢在鹰潭土壤模拟溶液中的腐蚀行为.利用自制的Ag/AgCl微型电极测定缝隙内不同位置的电极电位及氯离子溶度,研究材料在缝内的腐蚀倾向.实验结果表明：在腐蚀时间120 h内,浸泡时间的延长,缝内电极电位逐渐减小并趋于平缓;缝内氯离子浓度在缝隙底端逐渐增加,且增加幅度由缝口到封底逐渐增大,缝底氯离子浓度可以达到模拟溶液氯离子浓度的3倍.缝内腐蚀产物为铁的氧化物或氢氧化物.     

X80管线钢及其焊缝在库尔勒土壤环境中腐蚀行为

采用动电位极化、交流阻抗技术、失重法研究了X80管线钢及焊缝在库尔勒土壤模拟溶液中腐蚀行为,并结合X射线衍射仪（XRD）和金相显微镜（OM）对腐蚀产物及形貌进行表征。结果表明：随着浸泡时间的增加,金属腐蚀电位逐渐上升,电极表面的腐蚀产物层越来越厚,母材的腐蚀速率呈逐渐降低的趋势,而焊缝的腐蚀速率呈现减小后增大的趋势。金属电极表面内层的腐蚀产物膜Fe3O4对基体起到了一定的保护作用,减缓了X80钢及焊缝的腐蚀速率。当浸泡后期（30d）时,焊缝的产物膜因大量脱落而出现裂纹,有利于溶液中Cl-等腐蚀性离子的侵入,加速局部腐蚀的进行。相同浸泡时间下,焊缝的腐蚀程度高于母材,这是由于焊接过程使焊缝组织结构产生了不均匀性,导致焊缝晶界处的晶格畸变能和活性偏高,耐腐蚀性能差。     

二元锡合金心电电极模拟除颤恢复性能的研究

用不同金属材料制成电极,在检测心电过程中,具有不同的时间常数,由于其金相组织不同,在电极表面形成微电池的程度不同。研究发现：模拟除颤恢复性能与时间常数的大小和微电池作用有关。时间常数越小,模拟除颤恢复性能越好。二元锡合金电极,由于其微电池作用大,模拟除颤恢复性能优于相应的纯金属电极。     

拉伸状态对涤纶薄膜电化学不均匀性的影响

采用铜质和铁质丝束电极研究了涤纶薄膜在5％氯化钠溶液中的电化学不均匀性．研究表明，拉伸及未拉伸的涤纶薄膜，其电位分布是不均匀的，拉伸可提高涤纶薄膜电位分布的均匀性，减小电位的分布区间.拉伸在一定程度上可提高涤纶薄膜电位分布的总体水平．经拉伸的涤纶薄膜在一定的浸泡时间内仍维持电子导体的特性．采用丝束电极，可以对拉伸状态涤纶薄膜电化学不均匀性的影响进行研究．     

N80钢电极在水溶液体系中电位振荡现象

简要介绍了金属电极电化学过程中电流或电位振荡这一热点课题，报道了N80油管钢在水溶液中的自腐蚀电位振荡现象，此电化学振荡可能和金属表面水化层和腐蚀产物层竞相形成过程有关。对盐酸，有机缓蚀剂溶液体系中电位振荡现象也进行了观测和研究。     

基于有限元分析的管道腐蚀缺陷生长预测模型

由于服役环境的影响,管线钢表面不可避免的会出现腐蚀缺陷,腐蚀处会产生应力集中,促进裂纹形核。基于有限元方法建立了用于预测腐蚀缺陷形貌发展的应力和电化学多物理场耦合模型。在模型中采用了变形几何和动态网格技术,用以研究X70管线钢在海泥模拟溶液中的应力腐蚀行为和腐蚀形貌随时间发展情况。结果表明,机械⁃电化学效应对应力腐蚀裂纹的形核具有重要作用;较小的腐蚀缺陷宽度使应力集中程度加大,电极电位负移,腐蚀速率增大;随着操作压力增大,腐蚀缺陷底部的管壁出现大面积的高应力集中区域,因腐蚀导致的金属损失面积增大。     

跨海大桥钢管桩腐蚀模拟试验及耐久性跟踪研究

通过模拟试验,研究了3种不同类型的钢管桩样片在杭州湾海域5种环境分区中的腐蚀形态和电信号反馈。实验结果表明,涂敷环氧粉末涂层的钢管桩样片表面基本没有腐蚀,涂层完好无损,而其他钢管桩样片则出现不同程度腐蚀,其中浪溅区腐蚀最严重,泥下区腐蚀较轻微;腐蚀电位逐渐变负,随后出现稳态,最后趋向于零;浪溅区腐蚀电位最负,泥下区腐蚀电位最正;相同环境中,涂敷环氧涂层的样片腐蚀电位比其他样片更正,有焊缝样片腐蚀电位比无焊缝样片稍负。     

Electrochemical corrosion behavior of steel wires in a coalmine with a corrosive medium

A 6 × 19 point-contact hoisting cable was used as our research object to examine the progress of corrosion of steel wires in a laboratory, simulating the actual working conditions in a coalmine. An electrochemical method was used to investigate the corrosion behavior of steel wires with different surface treatments of a corrosive acid solution. The results show that anode activation of steel wire mainly occurs during pre-corrosion, where the anode activation process of bare steel wires is the fastest as is their corresponding corrosion speed, while the anode activation process of oil coated steel wires and their corresponding corrosion speed are the lowest. During the intermediate and late immersion periods,a passive film is generated on the surface of steel wires, which are gradually damaged with the passage of time. Local pitting corrosion occurs easily on the surface of steel wires with a high-polarization potential.Suitable equivalent circuits were chosen to fit the electrochemical impedance spectroscopy (EIS) of steel wires over various corrosive times and different surface treatments, which indicate good fitting results.The double electrical layer charge-transfer resistance increases in the sequence: bare steel wire,untreated steel wire and oil coated steel wire and their corrosion resistance decreases in turn, which is consistent with their polarization curves. The oil layer provides a certain protective effect on untreated steel wires, but its effect is not entirely clear.     

Anticorrosion performance of the coating/metal system by electrochemical impedance spectra

In order to investigate the anticorrosion performance of the organic coating/metal system, electrochemical impedance spectra (EIS) were measured in the 3.5wt% NaCl solution, the chemical component and the formation of corrosion products scale were analyzed by laser Raman microspectroscopy, and the pattern of the organic coating/metal system was observed by scanning electron microscopy (SEM). The characteristics and the delamination process of the organic coating/metal system were investigated systematically, and the emphases were on the transportation of the corrosive medium and the changes of the coating/metal interface. The results show that the impedance decreases at the initial immersion, then increases at the middle-immersion, and again decreases at last, which is related to the corrosion products scale. The concentration of Cl- in the coating, which destroys the corrosion products scale, increases with the immersion time.     

Corrosion behavior of aluminum alloys in Na2SO4 solution using the scanning electrochemical microscopy technique

The corrosion behavior of aluminum alloys 1060 and 2A12 in a 10 mM Na2SO4+5 mM KI solution was investigated by scanning electrochemical microscopy (SECM) and scanning electron microscopy (SEM).The potential topography and corrosion morphology results show that the potential of the sample surface over the same area changes with the increase of immersion time.The corrosion area becomes large,and the potential becomes more negative.The corrosion potential of the 2A12 alloy surface is lower than that of 1060 aluminum,and 2A12 alloy becomes easily corrosive.This is the reason that preferential dissolution in the boundary region of some intermetaUic particles (IMPs) occurs and different dissolution behaviors are associated with different types of IMPs because of different potentials.     

Potential’s fluctuation of rust preventing oil film during its degradation

Potential’s fluctuation of rust preventing oil film during its degradation was studied using wire beam electrode. Being non-destructive and simple, potential measurement is a very repetitive method. Other electrochemical testing method, e.g., polarization resistance, can breakdown the integrity of oil coating by DC current; EIS is time consuming. As a special electrochemical sensor, wire beam electrode contains 101 wires of mild steel wires, and it is helpful to improve the reproducibility of electrochemical test evidently. Using this electrode, the electrochemical parameters and their distribution which was related to underfilm corrosion process are measured directly so as to describe potential’s fluctuation of rust preventing oil film. It is pointed out that there is potential’s fluctuation on rust preventing oil film during its degradation, and this characteristic has direct effect on the self-repairing ability of rust preventing oil film. However, for the uncoated metal electrode and base oil film, there is no such behavior. It is also pointed out that inhibitors in the oil film have direct effect on its self-repairing ability. Project supported by the Natural Science Foundation of Hunan Province Synopsis of the first author Jiang Hangying, professor, born on July 4, 1928, majoring in Metallurgical Physicochemistry and Electrochemistry, have published about 100 papers.     

Optimal Parameters for Pricing of the American Put Options with Least Square Monte Carlo Simulation

Pricing the American put options requires solving an optimal stopping problem and therefore is a challenge for the setting up of simulation parameters. This paper uses least square Monte Carlo (LSMC) simulation to price the American put options and output the optimal simulation steps and number of Hermite basis functions. The results suggest: with different time cost and error tolerance, investors can choose the optimal simulation steps and number of basis function individually to price American put options numerically. Generally, with the pre-limitation in the section "least square Monte Carlo simulation", a number of basis equals 4, 15 000 simulation steps for Hermite basis function appear to be sufficient for the method.     

Temporal Characteristics of GaAs NEA and Alkali Metal Photocathodes

The temporal characteristics of GaAs NEA and alkali metal photocathodes are studied using Monte Carlo simulation method. The electron transit time and its distribution functions in the photocathodes are calculated.Based on the results, the time modulation transfer functions and temporal resolutions of the photocathodes are obtained. The results show that the response time and temporal resolution of alkali metal photocathode is in femitosecond order and those of GaAs NEA photocathode are in picosecond order.     

热加工材料动态再结晶介观组织模拟模型的研究进展

通过计算机模拟技术可以有效模拟金属材料热变形过程中动态再结晶组织的演化过程, 从而达到预测材料性能的目的。介绍了目前材料动态再结晶过程介观组织模拟的两种模型--元胞自动机(cellular automaton, CA)模型和蒙特卡洛(monte carlo, MC)模型的模拟技术及其研究进展, 重点分析了现有动态再结晶介观组织MC模型存在的问题并且提出了解决思路。     

热敏补偿网络优化设计的Monte Carlo法

给出了温补晶体振荡器（TCXO）热敏补偿网络优化设计的一种Monte Carlo法。具体做法是用最小二乘法建立优化设计的计算模型,用改进的解非线性方程组实根的Monte Carlo法确定电路的元件参数。本文方法具有计算形式简单、易于实现编程计算等优点,可方便地确定电路的元件参数。     

磁性薄膜自旋重取向的机制

采用Monte Carlo方法,使用微观电子自旋模型和具有偶极相互作用的Heisenberg模型,对16×16二维平方格子的磁性系统自旋重取向现象进行了研究.发现在一定参数下,系统呈现出包含4个不同区域的磁化曲线.从理论上再现了系统从垂直磁化向面内磁化转变时的宏观磁矩的丢失现象,得到了与实验观测相一致的结果.通过计算系统的自旋组态和能量特征,对产生这种现象的机制进行了分析.