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111.
Gr(C)纤维增强镁基复合材料的界面结构 总被引:4,自引:5,他引:4
采用真空—压力浸渗工艺制备Gr(C)/Mg复合材料,Gr/Mg材料界面上无化学反应迹象,有析出物γ相(Mg17Al12),该析出物形状、大小与制备工艺条件,主要是纤维预制件温度有关。C/Mg复合材料界面Al含量较基体高出2倍多,文中分析了可能的原因 相似文献
112.
根据热型连铸技术原理,建立了热型连铸凝固过程一维稳态温度场的物理、数学模型。通过数值计算,得出了铸型出口温度、冷却距离、拉铸速度和喷水冷却强度等工艺参数对铸坯固液界面位置的影响。计算结果与试验结果吻合。 相似文献
113.
G. X. Zhao M. Zheng X. H. Lv X. H. Dong H. L. Li 《Metals and Materials International》2005,11(2):135-140
The corrosion behavior of 13Cr martensitic stainless steel in a CO2 environment in a stimulated oilfield was studied with potentiodynamic polarization and the impedance spectra technique. The
results showed that the microstructure of the surface scale clearly changed with temperature. This decreased the sensitivity
of pitting corrosion and increased the tendency toward general (or uniform) corrosion. The capacitance, the charge transfer
resistance, and the polarization resistance of the corrosion product scale decrease with increasing temperature from 90 to
120 °C, and thus the corrosion is a thermal activation controlled process. Charge transfer through the scale is difficult
and the corrosion is controlled by a diffusion process at a temperature of 150 °C. Resistance charge transfer through the
corrosion product layer is higher than that in the passive film. 相似文献
114.
锂电极表面膜的组成和阻抗行为 总被引:1,自引:0,他引:1
介绍了锂电池中锂电极的表面膜的组成和阻抗行为,并根据其表面膜的阻抗行为提出了电化学模型。 相似文献
115.
116.
K HondaM Yoshimura R UchikadoT Kondo Tata N Rao D.A TrykA Fujishima M WatanabeK Yasui H Masuda 《Electrochimica acta》2002,47(27):4373-4385
Electrochemical characteristics for several redox systems at diamond films with highly ordered nanometer-scale cylindrical pores (‘nano-honeycombs’) were examined with cyclic voltammetry (CV) and electrochemical impedance measurements. The cyclic voltammetric anodic-cathodic peak separations for these nano-honeycomb electrodes were in the same range as those for polished polycrystalline diamond films, indicating that the involvement of the oxygen-terminated surface of the nano-pore walls, which should give rise to large peak separations for certain redox couples was only slight. Moreover, the peak currents in the CV were not enhanced to the extent expected on the basis of the roughness factors of the nano-honeycomb films. Ac impedance plots results indicated the existence of a concentration gradient of the reactant in the nano-pores, which is in agreement with theoretical predictions for charge transfer reactions in porous electrodes. The average concentration of the reactant (Fe2+/3+) inside the nano-pores was a factor of ca. 80 lower than that in the bulk electrolyte. The results of the impedance analysis also indicated an increase in the reaction resistances with decreasing pore diameters. 相似文献
117.
118.
P. Elumalai H.N. Vasan N. Munichandraiah S.A. Shivashankar 《Journal of Applied Electrochemistry》2002,32(9):1005-1010
Submicron size Co, Ni and Co–Ni alloy powders have been synthesized by the polyol method using the corresponding metal malonates and Pd powder by reduction of PdO
x
in methanol. The kinetics of the hydrogen evolution reaction (HER) in 6 M KOH electrolyte have been studied on electrodes made from the pressed powders. The d.c. polarization measurements have resulted in a value close to 120 mV decade–1 for the Tafel slope, suggesting that the HER follows the Volmer–Heyrovsky mechanism. The values of exchange current density (i
o) are in the range 1–10 mA cm–2 for electrodes fabricated in the study. The a.c. impedance spectra measured at several potentials in the HER region showed a single semicircle in the Nyquist plots. Exchange current density (i
o) and energy transfer coefficient () have been calculated by employing a nonlinear least square-fitting program. 相似文献
119.
120.
The electrochemical behavior of the bronze (Cu-8Sn in wt%) was investigated in 3% NaCl aqueous solution, in presence and in absence of a corrosion inhibitor, the 3-phenyl-1,2,4-triazole-5-thione (PTS). The inhibiting effect of the PTS was evidenced for concentrations higher than 1 mM for the cathodic process whereas its effect was clearly seen with a concentration as low as 0.1 mM for the anodic process. A significant positive shift of the corrosion potential was also observed, and its inhibiting effect increased with both its concentration and the immersion time of the sample. From voltammetry and electrochemical impedance spectroscopy experiments, the inhibiting efficiency of the PTS was found to be in the 94-99% range for 1 mM concentration. Scanning electron microscopy and X-ray energy dispersion analysis of the specimen surface show the presence of sulphur on the surface. Raman micro-spectrometry study confirms the protective effect of the PTS in aqueous solution through three types of interactions with the electrode, namely the adsorption of the inhibitor in a flat configuration, the formation of copper-thiol molecules, and when copper is released, the formation of a polymeric complex. 相似文献