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21.
Zhang Zhiming Lu Daohua Li Zhonglin Harbin Institute of Technology Feng Qiting Peng Chuanliou Heilongjiang Electric Power Electrode Manufacturer Harbin Wang Ruilin Northeast Electric Power Test Institute Shenyang 《中国焊接》1992,(2)
The welded joint of dissimilar heat-resisting steels 20Crl2MoV(F12)and 12 Cr2MoWVTiB(102)generally works around 600°C.In this paperthree kinds of ferritic electrodes are used for testing.They are R817 high-strength electrode(CrllMoVNi),R347 low-strength electrode(Cr2MoVWB)and newly-developed R507MoNb medium-strength electrode.The study on theinfluence of those three different electrodes on carbon migration,HIC and hy-drogen diffusion shows that medium-strength electrodes can well control thecarbon migration,and that the tendency to HIC in the joint formed by R817 issmaller than that by R347 instead.Considering the effect of weld metal transfor-mation on the restraint stress and hydrogen concentration of a joint,the hydro-gen distribution in the heat-affected zone(HAZ)is calculated by using finite ele-ment method(FEM)with stress and strain changing,and so the effect of thetransformation behaviour on HIC is revealed.In addition,newly-developedR507MoNb electrodes,tested the elevated-temperature property,oxidation re-sistance and creep rupture strength,have fulfilled the technical standards con-cerned and passed the examination of on-the-spot operation. 相似文献
22.
A thin film of poly(l-serine) was prepared via electropolymerization for the determination of trace levels of estradiol. In pH 5.0 phosphate buffer,
l-serine was oxidized during the cyclic potential sweeps between −0.60 and 2.0 V, forming a thin film at the electrode surface.
The electrochemical behavior of estradiol was investigated. The oxidation peak potential of estradiol shifts negatively at
the poly(l-serine) film-coated glassy carbon electrode (GCE) compared with that at the bare GCE. Otherwise, the oxidation peak current
greatly increases at the poly(l-serine) film-modified GCE. These phenomena suggest that the poly(l-serine) film exhibits catalytic activity towards the electrochemical oxidation of estradiol. Based on this, a sensitive,
rapid and simple electrochemical method was proposed for the determination of estradiol. The limit of detection is evaluated
to be 2.0 × 10−8 mol L−1. Finally, this method was successfully used to determine estradiol in blood serum. 相似文献
23.
Ahmad Nozad Golikand Elaheh Lohrasbi Mohammad Ghannadi Maragheh Mehdi Asgari 《Journal of Applied Electrochemistry》2008,38(6):869-874
The effect of carbon surface oxidation on platinum supported carbon particles (Pt/C) with nitric acid was investigated by
cyclic voltammetry, electrochemical impedance spectroscopy, polarization experiments and chronoamperometry. Cyclic voltammograms,
polarization curves and electrochemical impedance spectra showed that the treated catalyst had much larger active surface
area and higher ionic conductivity than the untreated catalyst, and provided enhanced performance for oxygen reduction. The
formation of acidic groups was examined by IR spectra. The Pt/C surface oxidation had a large effect on the performance of
a gas diffusion electrode for oxygen reduction reaction. 相似文献
24.
A simple method has been devised for immobilization of acetylcholinesterase (AChE) covalent bonding to a multiwall carbon
nanotube (MWNT)-cross-linked cellulose acetate composite on a screen-printed carbon electrode (SPCE) and a sensitive and disposable
amperometric sensor for rapid determination of carbaryl pesticide is proposed. The immobilized enzyme was preserved on this
film because of the excellent biocompatibility and non-toxicity of cellulose acetate. Based on the inherent conductive properties
of the MWNT, the immobilized AChE had greater affinity for ATCl and excellent catalytic effect in the hydrolysis of ATCl.
MWNT improved the interface enzymatic hydrolysis reaction and increased the amperometric response of the sensor. Under optimum
conditions, the inhibition of carbaryl on AChE increased linearly with the increasing concentration of carbaryl in two ranges,
from 0.01 to 0.5 μg mL−1 and from 2 to 20 μg mL−1, with the correlation coefficients of 0.9985 and 0.9977, respectively. The detection limit was 0.004 μg mL−1 taken as the concentration equivalent to 10% decrease in signal. The sensor showed acceptable stability, accuracy and could
be fabricated in batches, thus it is economic and portable. This type of disposable enzyme-based amperometric sensor has extensive
application potential in environmental monitoring of pesticides. 相似文献
25.
Debasmita Das Purabi Rani Samaddar Pratik Kumar Sen Kaushik Das 《Journal of Applied Electrochemistry》2008,38(6):743-749
Galvanostatic steady state current potential measurements were carried out for oxidation of a series of aliphatic alcohols
having varying number of hydroxyl groups. The anodically deposited layer of MnO2 on platinum was used as the electrode material. The deposit was characterised by scanning electron microscopy (SEM), energy
dispersive X-ray analysis (EDAX) and electrode potential measurements. The catalytic role of MnO2 in the electro-oxidation of alcohols was indicated by the chronopotentiograms and the cyclic voltammograms. An analysis of
the electrochemical data indicated a catalytic EC mechanism in which Mn (V) is generated electrochemically and consumed chemically
in succession. Based on this and the hydrogen bonding interaction between alcoholic hydroxyl groups and MnO2 layer, a mechanism was proposed which accounts for the variation in the observed electrochemical reaction orders. Tafel behaviour
was found to be followed only approximately. Current efficiency of the electrochemical oxidation of polyols was studied. Replacement
of platinum by carbon as current collector was found to leave the electrocatalytic activity of the MnO2 deposit practically unaltered. 相似文献
26.
Teresa Łuczak 《Journal of Applied Electrochemistry》2008,38(4):469-476
The electrooxidation of phenylethanolamine (2-amino-1-phenylethanol) at a gold electrode in alkaline electrolyte has been
studied. Measurement of the differential capacitance of the electric double layer versus the electrode potential has shown
that the adsorption of phenylethanolamine at the gold-solution interface plays a significant role in the oxidation mechanism.
The effect of amine concentration, electrolyte pH and potential scan rate on the electrooxidation is analysed. 相似文献
27.
S. Zisekas G. Karagiannakis C. Kokkofitis M. Stoukides 《Journal of Applied Electrochemistry》2008,38(8):1143-1149
The reaction of NH3 decomposition was studied on Ag in a proton conducting double chamber cell-reactor. The proton conductor was a strontia-ceria-ytterbia
(SCY) perovskite of the form SrCe0.95Yb0.05O3−α. The reaction was studied at 350–700 °C and atmospheric total pressure. The proton transference number (PTN) was calculated
by simultaneous measurement of the imposed current and the proton flux and it was found to vary between 0.5 and 0.7. The effects
of imposed current, temperature and inlet gas composition on the reaction rate and the PTN, were examined. Although the faradaic
efficiency (Λ) remained near unity in all experiments, reaction rate enhancements (ρ) as high as 57 were achieved. An up to
90% decrease in the activation energy of the reaction was observed when protons were electrochemically “pumped” away from
the catalyst. 相似文献
28.
通过对铸造湿型小件产品缺陷典型实例的原因分析,从型砂的选择及配制、造型工艺、浇注工艺等方面提出控制缺陷产生的工艺方法。 相似文献
29.
30.
We report here a non-enzymatic detecting electrode strip for fast monitoring of uric acid in human whole blood. A single-use amperometric uric acid sensor strip, incorporating a three-electrode configuration, has been fabricated on a polypropylene substrate using low cost screen-printing (thick-film) technology. Both the working and counter electrodes were prepared by screen-printing commercial carbon ink. The integration on the same support of pseudo-reference electrode was obtained by screen-printing a commercial silver ink and subsequent electrochemical pretreatment. Simply by placing a 20 μl human whole blood drop on the strip is enough for uric acid analysis by square-wave voltammetry. Real human whole blood samples were analyzed by this method and compared to the phosphotungstic acid clinical test procedure with satisfactory results. 相似文献