溶液电阻对稳态极化曲线测量的影响及一种消除此影响的数据处理方法

如果电极反应过程遵循Tafel规律,则在进行稳态极化测量情况下,可以用本文提出的数据处理方法对用等间距恒电位测量或等间距恒电流测量的极化数据进行处理,求得参考电极至工作电极之间的溶液电阻和Tafel斜率的数值,从而得到消除了溶液电阻欧姆电位降的真实极化曲线.计算机模拟结果和实验结果都证明,即使在溶液电阻并不大的介质中,如果腐蚀电流密度比较大,溶液电阻对于极化测量的影响也不可忽视.     

磁场对铁在氯化钠溶液中阳极溶解速率的影响

采用动电位极化和恒电位极化等方法,研究了磁场对铁在0.2 mol/L氯化钠溶液中阳极溶解速率的影响。结果表明：磁场加速了铁的阳极溶解速率;在0 T磁场下动电位极化后,铁电极表面宏观均匀;在0.4 T磁场下动电位极化后,铁电极表面与磁场方向平行的两侧出现局部加速溶解;恒电位极化时,外加磁场下铁-电极溶液界面达到稳态所需的时间比无外加磁场下所需的长;在0 T和0.4 T磁场下恒电位极化时,在较宽的电位范围内磁场对阳极电流的增强系数相近。     

用丝束电极研究混凝土中钢筋腐蚀的不均匀性

用8×8阵列丝束电极模拟研究了混凝土中钢筋的腐蚀.将混凝土试样浸泡在10 %NaCl溶液中,通过测量铁丝束电极的自腐蚀电位和极化电阻,获得了在相同埋置深度和不同埋置深度时,铁丝腐蚀的电位、极化电阻和腐蚀速度分布等信息,研究了混凝土结构和氯离子浓度对它们的影响.结果表明,混凝土中铁丝腐蚀不均匀.自腐蚀电位和极化电阻较分散,电位随时间负移、极化电阻变小,丝束之间的电位差增大.随铁丝埋入深度增加,电位负移量、氯离子浓度和腐蚀速度都减小、极化电阻增加     

腐蚀电化学测量中溶液电阻的补偿

从测量仪器、测量方法、测量范围区间以及测量结果的数值修正等几方面介绍了在腐蚀电化学测量中如何消除工作电极与鲁金毛细管间溶液电阻的影响,在实际测试过程中应该根据实际情况来选择合适的方法。在进行数值修正的时候要注意:不论是利用等距离法计算的结果还是利用EIS测量的结果,总是有一定的适用范围,特别是在强极化区,其溶液电阻由于溶液中离子运动速度的增加以及电极表面附近离子浓度的变化而减小。因而利用EIS结果及等距离法计算出的溶液电阻Rsol在相应的电位范围内是适用的,而不能将其推广到整个极化测量区间,否则将会引起较大的误差。     

AZ31和AZ61镁合金在MgSO4溶液中的电化学行为对比

用失重法、线性电位扫描、恒流放电对比研究了AZ31和AZ61两种镁合金在MgSO4溶液中的电化学行为。线性电位扫描结果表明,AZ31合金的极化电阻小于AZ61合金,电化学活性优于AZ61合金,说明其自腐蚀速率大于AZ61合金,这与失重法所得结果相一致。在恒流放电中AZ61合金的电极电位更负、更平稳,电流效率也更大,在电池中具有更好的应用价值。     

不锈钢局部腐蚀过程中氢去极化反应研究

用恒电位失重法和Ｔａｆｅｌ外推法绘制了１Ｃｒ１３和０Ｃｒ１８Ｎｉ９两种不锈钢在各自模拟闭塞区溶液中的极化图，并叠加了外表面极化的影响，得到了闭塞电池在开路状态下以及在外表面极化作用下的放氢速度和腐蚀速度。进一步阐明闭塞电池加速腐蚀的原因是在临ｐＨ值处发生了钝态／活态转变，从根本上改变了阳极过程，同时使内外电位差扩大，外表面的极化作用增大。     

恒电量微扰下涂装金属体系极化电位响应式的理论推导

恒电量微扰下的过渡过程可用一组线性微分方程组表示,求解的关键是确定其初始条件值。在恒电量扰动瞬间,有溶液电阻和忽略溶液电阻的暂态过渡过程的机制不同,因而极化电位随时间变化的函数关系也不一样。有溶液电阻时,电荷的转移和传输不能瞬间完成,需要一定的传递时间,即极化电位不会发生突变;而无溶液电阻时,依据基尔霍夫定律,在恒电量扰动瞬间,极化电位必将发生突变。同时电路受恒电量控制,无论突变瞬间或电量传递的整个过程都必须遵守电荷守恒原理。以此建立恒电量激励下过渡过程的初始条件。     

磁场对铁在不同电位高氯酸钠溶液中阳极溶解的影响

在不同磁场条件的0.1mol/L NaClO_4溶液中对铁阳极进行了动电位极化和恒电位极化,研究了磁场对铁阳极溶解的影响。结果表明:磁场使铁的开路电位正移,降低了极化曲线低电位区的电流密度,增大了高电位区的电流密度和阳极极化曲线线性段的斜率;恒电位极化时,低电位下磁场的作用与施加磁场的顺序有关,在高电位下磁场会增大电流密度,与动电位极化曲线的结果一致;磁场作用下高速溶解后铁电极表面出现月牙形局部腐蚀形貌。     

磁场对车轴钢在NaCl溶液中腐蚀速率及阳极电流密度的影响

采用极化曲线和恒电位极化的方法,研究了磁场对车轴钢在自然充气的NaCl溶液中的腐蚀速率和阳极电流密度的影响。结果表明：磁场对较短浸泡周期内试样的腐蚀速率有显著的加速作用,而在较长时间浸泡周期内,磁场的影响减弱;磁场导致试样的自腐蚀电位正移,使得阳极极化曲线起始段的电流密度降低;在阳极极化曲线线性区间进行恒电位极化时,在较低电位下极化一段时间后电流密度能达到稳态,而在较高的电位下极化时电流密度先急增然后线性下降,外加磁场后阳极电流密度出现小幅增加,表明在该电位下极化时电极反应速率并非由带电离子离开电极表面的传质过程控制。     

阳极极化状态下铁电极的交流阻抗

研究了铁电极在中性Na_2SO_4溶液中恒电位阳极极化下。和在不同pH的H_2SO_4/Na_2SO_4溶液中腐蚀电位下的交流阻抗特性。当pH>3.5时,铁电极的界面电容急剧增大至10~3μF/cm~2数量级。而铁电极在中性Na_2SO_4溶液中的界面电容为铁电极上覆盖的Fe(OH)2的电容。通过恒电位阳极极化状态铁电极的高频和低频部份的阻抗特性分析,建立了阳极极化状态铁电极的等效电路。用交流阻抗计算了极化电流密度,其值与同样条件下测得的稳态电流密度相等,说明阳极极化状态下交流阻抗测定的适用性。     

Effects of sputtering conditions on electrochemical behavior and physical properties of Ni-Mo alloy electrode

1 Introduction Many transition metal alloys with binary and ternary compositions have been studied as hydrogen evolution reaction electrodes in water electrolysis[1- 6]. The activity of such metal alloys for the hydrogen evolution reaction depends on at l…     

冷轧带钢电解清洗极板腐蚀机理和原因

采用线性电位扫描法研究了碳钢在不同脱脂剂浓度下的阳极极化过程,进一步研究了碳钢在不同不同脱脂剂浓度条件下、不同电位下的恒电位、恒电流电解行为,在此基础上对生产现场进行了考察。电化学实验表明：碳钢阳极极化过程依次经历活化区、钝化区、过钝化区及极限区;活化区基体活化溶解电流小,不影响电极寿命;过钝化区电极表面开始发生析氧反应;极限区析氧反应达到极限,使基体腐蚀反应大量发生,电极寿命降低;脱脂剂浓度越低、阳极电位越高,电极表面基体溶解反应速率越大,相应电极使用寿命越短。实际生产中,极板表面由于电流分布不均使其局部电流超过极限电流导致局部腐蚀发生,而电解槽内极板安装精度、电极表面气泡无法逸出、极板表面污泥淤积等都均会影响电流分布。     

Anodic dissolution of iron in acidic chloride solutions

The dissolution of iron in acidic chloride solutions was studied by both rotating disc and impedance techniques. Two regions of different slope were observed in the Tafel graphs after the effects of diffusion were eliminated. The Tafel slope was seen to change from ca. 44 to ca. 85 mV/decade at more positive potentials. The lower slope was confirmed by impedance measurements. An electrode reaction sequence is proposed for the dissolution reaction in the region where the Tafel slope is ca. 44 mV/decade.The addition of decylamine reduced the rate of the dissolution reaction, but the form of the polarization curves and the mechanism of dissolution remained unchanged. It was also established that decylamine is not involved in the electrode reaction of the dissolving polycrystalline iron.     

磁场对Cu/NaCl体系表观Tafel区阳极溶解的作用

采用线性电位扫描极化曲线测试 ,以及恒电位极化下磁场扰动法研究了磁场对铜在氯化钠溶液中阳极溶解的作用。在阳极表观 Tafel区 ,无磁场时恒电位极化然后外加磁场使阳极电流密度增大 ;有磁场时恒电位极化然后撤去磁场使阳极电流密度减小。磁场通过加速电极溶液界面的传质过程而加速阳极溶解。由于 Cu/ Na Cl与Fe/ H2 SO4体系阳极 Tafel区速率控制步骤不同 ,会导致不同的磁场效应作用     

方波动电流扫描的响应函数及其应用

应用 Laplace 变换分析求得了在线性极化区内向金属电极施加方波动电流扫描的响应函数方程.它在 E～i 座标系中为两条长度相等的平行线。用它可以方便地测量 R_P、C 和 R_S 等电化学参数而不受溶液电阻的影响。本方法对弛豫时间常数较大的体系尤为适用。     

Critical analysis of some electrochemical techniques including polarization resistance,for the study of zinc coating performance in near neutral chloride solutions

Corrosion rate determination in near neutral solutions by Tafel slope back extrapolation of polarization curves can lead to dubious results due to mass transfer effects.With polarization resistance measurements, attainment of the steady-state following polarization takes considerable time, up to 10 min, and experiments become lengthy, demanding constant corrosion potentials.Results are discussed for reducing experimental times by (a) transient linear polarization, and (b) obtaining charge-transfer resistance instead of polarization resistance.Under the present conditions contributions from diffusion of anodic reaction product must be eliminated from the experimental measurement if corrosion rates are to be accurately calculated from the Stern-Geary equation.The linear range for polarization curves of potential vs. current density near the corrosion potential is only ± 1·3 mV for the zinc system. Results taken in excess of this range can lead to inaccurate corrosion rates.Results are discussed for determining Tafel slopes, which are obtained to convert polarization resistance or charge-transfer resistance to corrosion rate, by the Barnartt low polarization method.     

电化学方法检测混凝土横梁中高强钢丝的腐蚀

通过测量镦头自腐蚀电位等参数，判断吊杆钢丝的腐蚀概率；以吊杆钢丝和CCMP-I检测探头分别作为研究电极，运用恒电量技术检测获得Rp值和Tafel常数，从而计算出腐蚀速率icorr.检测结果表明：压浆对增强钢丝的保护有成效；由于锈蚀原因不同，各短吊杆位置钢丝的锈蚀速率差异很大．     

Hydrogen absorption monitoring of sputter-deposited Ti film in seawater

Hydrogen absorption in Ti film sputter-deposited on glass plate immersed in sodium chloride solution of seawater concentration was monitored using resistometry. Increase in electric resistance due to increase in hydrogen content or growth of hydride in Ti during cathodic polarization was evaluated. A monitoring system was developed in which a couple of Ti films were used to reduce influence of temperature-fluctuation on resistance; one was used as a working electrode exposed to electrolyte solution and another was used as a reference resistance with silicon sealant coating. Two films were connected electrically in series, and applied by constant AC to measure resistance of the working electrode as relative value against the reference resistance. Increase in resistance during cathodic polarization at −0.8 V_RHE was observed after some induction period. Scratching test during cathodic polarization did not provide major effect on hydrogen absorption.     

pH值对X120钢在模拟鹰潭酸性土壤溶液中电化学行为的影响

采用电化学阻抗谱法和动电位极化法研究了不同pH值(3.5～6.5)和不同外加电位(-0.58～-1.20V)对X120钢在模拟鹰潭酸性土壤溶液中电化学行为的影响。结果表明,随着pH值的升高,自腐蚀电位整体呈下降趋势,在pH=5.5附近电位有反弹;高pH值溶液中电极反应电阻R_t普遍大于低pH值下的R_t,即pH越高电极腐蚀过程的阻力越大;在同一pH值下,随着外加电位的降低,R_t先增大后减小,在-0.75 V附近达到最大值;这是由于电极过程在阳极电位区受活化控制,在-0.75 V附近受活化和扩散共同控制,而阴极电位区重新受活化控制所致。另外,快慢速率扫描动电位极化曲线反映的pH值对阴阳极极化行为影响的规律与阻抗谱反映的规律一致。