曹楚南
,
张鸣镝
,
林海潮
腐蚀学报（英文）
通过腐蚀电位、极化曲线与交流阻抗测量研究了3种伯胺和丙炔醇对铁在盐酸中的缓蚀作用类型。结果表明,3种伯胺的缓蚀作用是几何覆盖效应,而丙炔醇的缓蚀作用则来自负催化效应。还证明,在强阳极极化的Tafel 直线区间,十二烷胺吸附在电极表面的覆盖率θ不随电位改变,十四烷胺的θ随电位的升高而增大。丙炔醇使铁阳极溶解反应活化能位垒增高的量.fa(θ)随电位升高而减小,其数值为df_a(θ)/dE=-73J·mol_-1.mV-1。
关键词:
缓蚀剂
,
Inhibitor
,
Acid
,
Iron
,
Impedance
Haitao YE
,
Olivier GAUDIN
,
Richard B.JACKMAN
,
null
,
null
,
null
材料科学技术（英文）
The first measurement of impedance on free-standing diamond films from 0.1 Hz to 10 MHz up to 300℃ were reported. A wide range of chemical vapour deposition (CVD) materials were investigated, but here we concentrate on `black' diamond grown by microwave plasma enhanced CVD (MWPECVD). The Cole-Cole (Z' via Z'') plots are well fitted to a RC parallel circuit model and the equivalent resistance and capacitance for the diamond films have been estimated using the Zview curve fitting. The results show only one single semicircle response at each temperature measured. It was found that the resistance decreases from 62 MΩ at room temperature to 4 kΩ at 300℃, with an activation energy around 0.51 eV. The equivalent capacitance is maintained at the level of 100 pF up to 300℃ suggesting that the diamond grain boundaries are dominating the conduction. At 400℃, the impedance at low frequencies shows a linear tail, which can be explained that the AC polarization of diamond/Au interface occurs.
关键词:
Black diamond
,
diamond
,
Impedance
,
spectroscopy
,
Act
K.Jafarzadeh
,
T.Shahrabi
材料科学技术（英文）
In this research, EIS (electrochemical impedance spectroscopy) technique was utilized to study the pitting corrosion behaviour of AA5083-H321 aluminum-magnesium alloy in 3.5% NaCl solution. Impedance spectra were obtained during 240 h of exposure of the sample to the test solution. The surface and cross-section of the samples were studied by scanning electron microscopy (SEM) and EDAX (energy dispersive analysis of X-ray) analysis. The results indicated that as the resistance of the passive layer on intermetallic particles is very small, this parameter on the sample surface layers is controlled by that of pure passive layer. However, the capacitors in the proposed equivalent circuit are replaced with the constant phase elements (CPE), due to non-uniformity and occurrence of pitting corrosion on the surface. The outward diffusion of Al+3 ions through the passive layer and the thickening of this layer cause the impedance decrease in the first 24 h and increase afterwards. The detachment of intermetallic particles from some of pits and the accumulation of the corrosion products inside some others are factors that prevents the continuation of cathodic reactions on the top of the intermetallic particles.
关键词:
Corrosion
,
null
,
null
,
null
,
null
刘希邈
,
张睿
,
詹亮
,
龙东辉
,
乔文明
,
杨俊和
,
凌立成
新型炭材料
doi:10.3969/j.issn.1007-8827.2007.02.011
分别以炭气凝胶(CAG),炭黑(CB)以及石墨(G)为导电剂与KOH活化法高比表面积活性炭(HSAC)制备复合电极,组装成双电层电容器,在(C2H5)4NBF4/丙烯碳酸盐电解液体系中进行交流阻抗测试分析.应用动力学及电子传递控制的等效电路模型对各电极的实验阻抗数据进行拟合得到相应的模型参数,串联溶液电阻Rs、极化电阻Rp、能斯特边界层厚度δ及平均孔内离子扩散系数D.结果表明,炭气凝胶复合电极的孔内离子扩散系数D最高,极化电阻Rp与炭黑复合电极接近.炭气凝胶电极的内阻为各电极中最低并且具有最高的比电容.
关键词:
炭气凝胶
,
活性炭
,
双电层电容器
,
电容
,
阻抗
Qing XU
,
Wen CHEN
,
Duanping HUANG
,
Runzhang YUAN
材料科学技术（英文）
Doped SrTiO3 capacitor-varistor multifunctional ceramics were fabricated by a single sintering process. AC complex impedance analysis was performed to investigate electrical features of grains and grain boundaries for both as-reduced ceramic and reoxidized ceramics.The results showed that the as-reduced ceramic exhibited inductive response at high frequencies above 2 MHz, which is attributed to the contribution of electron behavior in semiconducting grains.The high frequency inductive response disappeared in impedance plots of reoxidized ceramics.
关键词:
Strontium titanate
,
null
,
null
,
null
