球状锌粉对无机富锌漆阴极保护性能的影响

研究了球状锌粉取代片状锌粉对无机富锌漆阴极保护性能的影响。采用开路电位法评价涂层的阴极保护性。用差示扫描量热法测涂层锌含量,并测试涂层在NaCl溶液中浸泡初期的交流阻抗谱。开路电位测试结果表明,取代后阴极保护期缩短,随着取代比的增大,阴极保护期延长,向未取代时的水平靠拢;差热法和交流阻抗的测试结果显示,随着取代比的增加,涂层锌含量增加,涂层中活性锌的面积减小。锌含量的增加有利于阴极保护性能的提高,而活性锌面积的减小不利于阴极保护性能,由于两个因素的综合作用,导致了球状锌粉取代后涂层的阴极保护性能下降,但又随着取代比的增大而增强。采用恒电流溶解法,快速评价富锌漆阴极保护性,并与传统的开路电位法比较。实验结果表明,恒电流溶解法与开路电位法用于评价富锌漆的阴极保护性能时有较好的相关性。     

碱液中添加酒石酸钾对锌电极性能的影响

利用循环伏安、恒电位阴极极化和动电位线性扫描等测试手段,研究了向 6mol/LKOH(ZnO饱和 )水溶液中加入酒石酸钾对锌电极电化学性能的影响。结果表明,添加酒石酸钾后,不仅可以增大锌电极的析氢过电位,减小腐蚀电流密度,而且可有效抑制锌枝晶的形成,其中以w(酒石酸钾) =2%为最优,恒电位阴极极化电流由未加时的 927. 7mA降为 72. 2mA。     

不锈钢浓硫酸冷却器恒槽压法多系统阳极保护技术研究

根据阴阳极极化值互相抑制原理和恒槽压法的自控原理及实验室试验,提出用一台恒电位仪控制多台不锈钢浓硫酸冷却器阳极保护新技术。该控制方法既比单台恒电位法控制优越,又比多路恒电位法控制优越。该技术无需铂控制参比电极,藉恒定E_(槽压)值使E_(维钝)电位处在最佳维钝电位区,电流分散能力好,E_(维钝)电位分布均匀,能克服气液界面电解腐蚀,保护效果好。且致钝操作、日常维护均比恒电位法简便,仪器的使用率高,投资少,便于推广应用。     

不锈钢在循环冷却水中点蚀倾向的研究

本文主要采用恒电位步进法,测定两种不锈钢(18—8、304L)在循环冷却水中的击破电位(E_b)和保护电位(E_p),并用动电位扫描法和恒电位法校核E_b值。实验结果给出氯离子浓度和介质温度对击破电位和保护电位的影响关系。比较了两种不锈钢的点蚀倾向。     

Ni-W-P合金在铁上电沉积时阴极极化的研究

用恒电位法研究了在硫酸盐体系中电沉积N i-W-P合金时的阴极极化行为,得出在镀液中不同组分对阴极极化的影响不同,加入H8C6O7可提高阴极极化,加入N aH2PO2.H2O可使极化减小,对二次电流的分布不利,在保证镀层中磷含量的前提下,应尽量减小N aH2PO2.H2O的含量。     

流动电位和通量法表征中空纤维超滤膜的污染程度及清洗效果

用流动电位和通量法表征PS中空纤维膜,研究离子强度、离子种类及pH值对膜的流动电位和通量的影响,同时测量了膜的等电点,结果表明流动电位系数（v）随浓度的增大而减小,等电点随电解质中阳离子价态增大而升高.对0.001mol/L的CuCl2,FeCl3和AlCl3溶液,在pH=6.8时的污染实验,发现污染后流动电位和通量值都有所下降,等电点则有所上升,且通量下降到一定值以后几乎不再下降,经过有效清洗后,流动电位和膜通量恢复到了原来的99%以上,这表明污染只发生在膜表面.     

电化学测试技术在集成电路制程化学机械抛光中的应用现状

简述了包括开路电位法、极化曲线法、恒电位法、电化学阻抗谱在内的常规电化学测试技术的原理.总结了近几年内这几种电化学测试技术在化学机械抛光领域研究中的应用现状,展望了未来的发展方向.     

掺杂稀土铈对电化学合成聚苯胺膜耐蚀性的影响

通过电化学恒电流法,采用苯胺-硫酸电解液在钢片表面合成聚苯胺膜,利用电化学测试技术、扫描电子显微镜、能量散射谱仪和红外光谱仪研究掺杂稀土铈对电化学合成聚苯胺膜在金属基底上的耐蚀性影响。结果表明,稀土铈的掺杂使聚苯胺膜的微观形貌由不规则团块状转变为小薄片正六边形形貌;掺杂稀土铈改性后的聚苯胺膜耐蚀性提高,其交流阻抗弧增大明显,膜层的腐蚀电位向正方向移动,腐蚀电流减小;10%HCI点滴腐蚀t达115 s。     

N(C_2H_4OH)_3对电合成氧化钴/聚苯胺复合膜腐蚀性能的影响

通过单因素实验研究了三乙醇胺(N(C_2H_4OH)_3)对恒电位法合成氧化钴/聚苯胺复合膜的影响。采用电化学测试技术、扫描电镜、X射线衍射和加速腐蚀实验等方法对膜层的耐腐蚀性能进行分析。结果表明,恒电位法合成的氧化钴/聚苯胺复合膜中,氧化钴以晶体形式存在,三乙醇胺的加入使复合膜的微观形貌由不致密不规则的片状形貌,转变为均匀致密的片状形貌。三乙醇胺加入2 g/L时,复合膜的自腐蚀电流达到9.09×10~(-7)A/cm~2,自腐蚀电位达到-0.152 V,10%HCl点滴腐蚀时间达496 s,10%NaOH点滴实验时间467 s,中性盐雾实验48 h未见锈蚀。     

电化学法制备石墨烯电极及其电容性能表征

为探究石墨烯的电容性能,本课题以纯石墨烯薄膜为基体,采用电化学法制备石墨烯电极,并研究在不同恒电位处理后获得电极的电容特征。利用恒流充放电曲线、红外吸收光谱以及X射线衍射图对电化学处理后的电极进行了结构性能表征。结果表明:在碱性电解液下石墨烯电极经恒电位处理后,展现出较为优异的电容性能,当2. 0 V恒电位处理时,石墨烯电极比电容可达279. 6 F/g,有望成为超级电容器领域理想的电极材料。     

成皂反应过程中的液膜振荡

试验发现,由Ca(OH)2饱和水溶液、油酸的煤油溶液和CTAB水溶液组成的W1／O／W2三相体系,其油水界面产生了pH、电势及电导率的不规则振荡。通过组份替换和添加物的比较,解释了产生振荡的原因和机理。振荡产生于油酸与钙碱之间的成皂反应。其生成的表面活性剂-钙皂为关键组份,CTAB是主要助剂。反应结束后,通以交流电,还发现了可逆振荡现象,并据乳液性能进行了解释。     

苯氧化固定床反应器的振荡操作研究

在苯催化氧化固定床反应器中，以进料浓度的规则和不规则方波形式，进行浓度振荡操作研究。结果表明，反应器的浓度振荡可以提高顺酐的收率，且不规则方波振荡可以达到比规则方波振荡更佳的效果。同时在工业反应器上得到了验证。     

Chloride ion influencing potential oscillation generated by formaldehyde oxidation

The effect of chloride ions (10⁻⁷ to 10⁻¹ M) on the potential oscillation generated by the oxidation of formaldehyde is investigated with polycrystalline platinum at 315 K in a sulfuric acid solution containing 0.1 M formaldehyde. When the chloride ion concentration is 10⁻⁵ M or lower, between the two current regions for the appearance of relaxational oscillations, a large-amplitude trapezoidal oscillation appears, which is alternately accompanied by a relaxational one at a lower current. At a still lower current, the relaxational oscillation changes to a sinusoidal one, which then produces a well-known chaos. When the chloride ion concentration is between 10⁻⁴ and 3 × 10⁻⁴ M, the relaxational oscillations disappear and the alternating oscillation shows chaos, the properties of which are different from those of the chaos already stated. When the chloride ion concentration is 10⁻³ M or greater, a simple large-amplitude trapezoidal oscillation prevails without alternation with the relaxational one, along with much less chaos. The surface adsorption state during the various observed oscillations is discussed on the basis of voltammograms measured at various chloride ion concentrations.     

Shil’nikov chaos in the oxidation of formic acid with bismuth ion on Pt ring electrode

We report experimental observations of potential oscillations in electrocatalytic oxidation of formic acid with bismuth ion on the Pt ring electrode. Potential oscillations were investigated under galvanostatic conditions. The presence of bismuth ion enables to get the low and stable potential values at larger current range. Periodic and Shil’nikov chaotic potential oscillations were observed at fixed current. To extract information from the oscillation pattern, we used time series, reconstructed attractor, next-maximum map, pattern formation of interfacial potential above ring electrode.     

酵母细胞连续发酵过程振荡现象的研究进展

振荡现象在连续发酵过程中普遍存在,本文综述了酿酒酵母连续发酵中不同类型振荡现象的研究进展。一类以乙醇连续发酵过程中参数振荡为代表的特殊振荡现象,普遍存在于工业发酵过程,对发酵系统的稳定运行造成不利影响。本文论述了这类振荡现象产生的机理、调控策略的研究进展及其潜在的应用价值。     

Electrocatalytic activity under oscillatory regime: The electro-oxidation of formic acid on ordered Pt3Sn intermetallic phase

Despite the considerable progress in the understanding of the mechanistic aspects of the oscillatory electro-oxidation of C1 molecules, there are apparently no systematic studies concerning the impact of surface modifiers on the oscillation dynamics. Herein we communicate on the oscillatory electro-oxidation of formic acid on ordered Pt₃Sn intermetallic phase, and compare the results with those obtained on a polycrystalline platinum electrode. Overall, the obtained results were very reproducible, robust and allowed a detailed analysis on the correlation between the catalytic activity and the oscillation dynamics. The presence of Sn in the intermetallic electrode promotes drastic effects on the oscillatory dynamics. The decrease in the mean electrode potential and in the oscillation frequency, as well as the pronounced increase in the number oscillations (and also in the oscillation time), was discussed in connection with the substantial catalytic enhancement of the Pt₃Sn towards the electro-oxidation of formic acid. The self-organized potential oscillations were used to probe the electrocatalytic activity of the Pt₃Sn electrode and compare it with that for polycrystalline Pt. The presence of Sn resulted in a significant decrease (2–11 times, depending on the applied current) of the rate of surface poisoning.     

含CTAB-苦味酸的水/油/水体系的液膜振荡规律

研究了水（CTAB-正丁醇水溶液）/油（含苦味酸的硝基苯溶液）/水（葡萄糖水溶液）体系的液膜振荡。通过改变CTAB的浓度、苦味酸等协同物的浓度研究了振荡曲线的变化规律。研究显示,CTAB浓度在3 mmol·L^-1以上才有振荡,随着浓度的增加,振荡频率变小;随着苦味酸浓度的增加,振荡频率增大,但超过1.5 mmol·L^-1前期没有振荡;苦味酸和其他协同物还对振荡曲线的规律性和重现性具有明显的影响。首次测定了电流-时间振荡曲线,发现其与电势-时间曲线具有类似的趋势,表明在液膜振荡研究中也可以通过监测电流的变化来监测振荡体系。采用自制的直型玻璃管装置,操作方便,重现性好,测定振幅可达50～200 mV。     

Unsteady auto-ignition of hydrogen in a perfectly stirred reactor with oscillating residence times

The ignition characteristics of a hydrogen–air mixture in a perfectly stirred reactor (PSR) with an oscillating residence time were investigated numerically. An unsteady numerical algorithm was developed and solved using a stiff-equation solver in order to investigate the unsteady auto-ignition behavior of the fuel/air mixture. The amplitude, frequency, and phase of the residence time oscillations were varied, and the effects on the simulated ignition behavior were recorded. Under small amplitude oscillations of the residence time, once ignited, the temperature in the reactor varied following the phase of the oscillations. Under larger amplitude variations, periodic ignition, and extinction events were observed. A critical frequency was observed, where the ignition delay time became significantly large than at the other frequencies. The existence of this critical frequency was found to depend on the phase of the residence time oscillation, and only occurred when the phase was such that the residence time decreased from the initial conditions. Ignition did not occur for frequencies of the oscillation in the residence time beyond 2.84 kHz, regardless of the phase. The physics of ignition delay for the case where the oscillatory residence time decreased initially could be clarified by investigating the time variation of characteristic chemical times of important reactions to ignition.At low frequencies of the residence time oscillation, similar behavior to that of the steady state was observed. However, the ignition delay time was found to be significantly different at high frequencies, especially for larger amplitude fluctuations in the residence time. Combustion of the fuel/air mixture could be sustained at shorter residence times under the oscillating residence time conditions than under the steady-state conditions. The reaction could not be sustained at high frequencies, and a pulsed-mode flame was observed, where the period of the ignition and extinction events was the same as the period of the oscillations in the residence time.The concentration of free radicals was found to increase with time prior to ignition, and the H radical concentration saturated at a maximum at the ignition time, indicating that the H radical concentration is a good indicator of ignition time under oscillating residence times.     

矩形双通道间脉动的非单值性试验研究

矩形平行通道流动不稳定性问题是影响紧凑装置安全运行的重要因素之一。文中在中国核动力研究设计院热工试验回路上进行了矩形双通道管间脉动试验。通过对各种热工水力参数和单通道加热的试验研究,得出结论:在低压低质量流速下,随着进口过冷度的增加,界限含汽质量分数先增加、后减小;随着系统压力的升高,质量流速脉动周期先变短、后变长;在低质量流速下,单通道加热时产生管间脉动的界限热流密度比双通道均匀加热情况下的高,在较高质量流速下,单通道加热时的界限热流密度比双通道均匀加热情况下的低。     

矩形通道内低压自然循环压降型脉动及其复合型脉动可视化研究

以去离子水为工质,对矩形通道内低压自然循环压降型脉动及其复合型脉动进行可视化实验研究,利用可视化手段拍摄脉动过程气相分布状态图像。通过流量脉动曲线与图像进行对照,分析流量脉动的物理过程及产生机理。实验过程中发现4类动态不稳定性：第Ⅰ类密度波（DWO_Ⅰ）、压降型脉动（PDO）、复合型脉动（SPO）及第Ⅱ类密度波（DWO_Ⅱ）。重点分析了压降型脉动与复合型脉动产生机理、影响因素及流动不稳定性边界。实验研究发现,受矩形通道挤压效应及稳压器内部可压缩空间影响,工质在稳压器和循环回路之间往复波动,形成压降型脉动,增大加热功率压降型脉动会叠加第Ⅱ类密度波形成复合型脉动。两类脉动的起始点会随入口过冷度增加呈现偏离趋势,并且压力增加,偏离趋势会随之增大。通过相变数、过冷度数等无量纲参数绘制了压降型脉动不稳定性边界。