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Materials Science and Engineering

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1999

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Articles 31 - 60 of 115

Full-Text Articles in Engineering

A Study Self_Passivation Of Passivie Film Of Stainless Steel In Vinylon Aldehyde Solution, Sifu Hu, Chuanbi Xu, Zhuqiu Cheng Aug 1999

A Study Self_Passivation Of Passivie Film Of Stainless Steel In Vinylon Aldehyde Solution, Sifu Hu, Chuanbi Xu, Zhuqiu Cheng

Journal of Electrochemistry

Properties of self_passivation for the anodic passive film of 1Cr18Ni9Ti and the firsthand passive film of SUS 36 stainless steel in vinylon aldehyde solution(H 2SO 4(240 g/L)+Na 2SO 4(70 g/L)+HCHO(25 g/L)+[Fe 3+ ](35.4 mg/L)+[Cl -](240 mg/L) at 70 ℃ were studied by galvanostatic and potentiostatic polarization mesurements. The effects of compponents of vinylon aldehyde solution, i.e. Fe 3+ and Cl -, on the passivation behaviours of stainless steel have also been investigated. The experimental results showed there is a conversion zone of the active/passive state if the area ratio of active/passive state on these stainless steel attained to a critical …

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The Techniques Of The Paired Electrosynthesis, Hongkun Zhang, Dengping Gu Aug 1999

The Techniques Of The Paired Electrosynthesis, Hongkun Zhang, Dengping Gu

Journal of Electrochemistry

In this Paper,we introduce our work on paired electrosynthesis.In conjunction with our research practice,we introduce electrolytic conditions,such as material of electrode ,courrent density and electrolytic temperature etc,as reference for researcher.We categorize the paired electrosynthesis techniques to widen our view on the paired electroorganic synthesis and to promote the deveopments of paired electrosynthesis techniques.

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A Study Of The Corrosion On Bronze, Hongfan Zhu, Hao Zhou Aug 1999

A Study Of The Corrosion On Bronze, Hongfan Zhu, Hao Zhou

Journal of Electrochemistry

The bronze is the treasure in chinese metallic antique, which was typified by product in Shang_Zhou period (three thousands years ago). Because of corrosion, archaeological messages,such as inscription and pattern on the surface of bronze, would be damaged then the value of bronze antique decreased. The bronze disease is a common disease which forms powdery rust on the surface of bronze in atmospheric environment, the powdery rust emerge from under incrusted rust, then spreads, and eventually leads to bronze damaged. This paper investigates the bronze disease. According to the chemical and electrochemical tests in simulated occluded cell, the variation in …

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Influence Of Thiourea And Its Derivate On The Process Of Cathodic Electrodeposition Of Copper, Dong Dong, Yunhui Yunhui, Aihong Zou, Yunxia Zhao Aug 1999

Influence Of Thiourea And Its Derivate On The Process Of Cathodic Electrodeposition Of Copper, Dong Dong, Yunhui Yunhui, Aihong Zou, Yunxia Zhao

Journal of Electrochemistry

The effects of thiourea and its derivate on the electrodeposition of copper from the dilute acid sulphate solutions have been studied by using potential sweep techniques at quasisteady state. Limiting current densities( I d),exchange current densities( i 0) and αn are obtained by data processing with the least square method.Thiourea has a depolarizing effect on the copper depositing at concentrations below 8 mg·L -1 ,and a polarizing effect at higher concentration (>10 mg·L -1 ),and it changes the mechanism of copper deposition reaction.Propenyltiourea and Phenylthiourea have a depolarizing effect on the copper depositing,but the mechanism of copper deposition reaction …

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Electrochemical Synthesis Of Fes Electrode And Its Behavior Measurement, Congsheng Guan Aug 1999

Electrochemical Synthesis Of Fes Electrode And Its Behavior Measurement, Congsheng Guan

Journal of Electrochemistry

The Potential for the electrochemical synthesis of FeS electrode has been obtained by cyclic voltammetry.FeS electrodes were synthesiaed by controlling Fe electrode at -1.0 V in LiCl_KCl_Li 2S and Li(FClI)_Li 2S melts and their behavior were measured also.The FeS electrode synthesized in molten Li(FClI)_Li 2S has the best charge and discharge properties.

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Design Of An Instrumentation System To Record Distribution Profile Of Snow Layer Temperature For Modelling Of Snow Avalanche Forecast, Raman Attri Aug 1999

Design Of An Instrumentation System To Record Distribution Profile Of Snow Layer Temperature For Modelling Of Snow Avalanche Forecast, Raman Attri

Raman K. Attri

The measurement of snow hydrological parameters is extremely important in developing a model for the predication of Snow avalanche as well as Snowmelt water in the rivers. When direct measurement of these parameters is practically difficult, its dependence on snow temperature is used to develop snow cover models. A robust model for avalanche forecasting requires a sophisticated instrumentation system which can measure the required temperature parameters at right data points within snow pack. A Snow Temperature Profile Sensing System along with Surface temperature Sensor has been designed to measure Snow temperature gradient, temperature distributions, and average temperature of snow pack, …

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Design Strategy Of Snow Depth Sensor Based On Ultrasonic Pulse-Transit Technique For Remote Measurement Of Snow Cover Thickness, Raman Attri Aug 1999

Design Strategy Of Snow Depth Sensor Based On Ultrasonic Pulse-Transit Technique For Remote Measurement Of Snow Cover Thickness, Raman Attri

Raman K. Attri

Snow cover thickness is one of the important parameter used in forecasting models for snow-melt, snow run-off water, snow avalanche release and other snow hydrological changes. Ultrasonic pulse transit method is being used for such applications universally. Reflected echo coming after reflection from highly irregular and non-smooth porous surface, is very low amplitude noise ridden signal. This received echo signal has to be conditioned to remove signal and processed to increase its amplitude to make it sufficiently detectable and to increase the probability of receiving back the reflected echo. A special design of Snow Depth Sensor based on Ultrasonic Pulse …

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Electrodeposition Of Cerium-Based Coatings For Corrosion Protection Of Aluminum Alloys, James O. Stoffer, Thomas J. O'Keefe, Xuan Lin, Eric L. Morris, Pu Yu, Srinivas Pravin Sitaram Aug 1999

Electrodeposition Of Cerium-Based Coatings For Corrosion Protection Of Aluminum Alloys, James O. Stoffer, Thomas J. O'Keefe, Xuan Lin, Eric L. Morris, Pu Yu, Srinivas Pravin Sitaram

Chemistry Faculty Research & Creative Works

A process for enhancing the corrosion resistance of an aluminum-containing component with a cerium based coating. An aluminum-containing cathode and an oxygen- evolving anode are immersed in an electrolyte comprising water, solvent, oxidizing agent and cerium ions. An electrical current is passed through the electrolyte by applying electrical current to deposit a cerium based coating onto the cathode. An electrolyte for use in depositing a cerium based coating. An electrodeposited cerium-based coating. An aluminum aircraft structural component having a cerium-based coating thereon.

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Models For Magnetoresistance In Tunnel Junctions, Shi C. Zhang, P. M. Levy Aug 1999

Models For Magnetoresistance In Tunnel Junctions, Shi C. Zhang, P. M. Levy

Materials Science and Engineering Faculty Research & Creative Works

We show there are putative pitfalls when one predicts the magnetoresistance of magnetic tunnel junctions (JMR) based on different toy models. Amongst them are the sensitivity of the MR to the details of the profile of the potential barrier between the metallic electrodes and the insulating barrier, and the common assumption of only one band of electrons. We indicate the ingredients that are necessary to obtain a more complete description of the JMR of magnetic tunnel junctions.

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Macrosegregation Caused By Thermosolutal Convection During Directional Solidification Of Pb-Sb Alloys, S. N. Ojha, G. L. Ding, Y. Lu, J. Reye, Surendra N. Tewari Aug 1999

Macrosegregation Caused By Thermosolutal Convection During Directional Solidification Of Pb-Sb Alloys, S. N. Ojha, G. L. Ding, Y. Lu, J. Reye, Surendra N. Tewari

Chemical & Biomedical Engineering Faculty Publications

Pb-2.2 and 5.8 wt pet Sb alloys were directionally solidified with a positive thermal gradient of 140 K cm(-1) at growth speeds ranging from 0.8 to 30 mu m s(-1), and then quenched to retain the mushy-zone morphology. Chemical analysis along the length of the directionally solidified portion and in the quenched melt ahead of the dendritic array showed extensive longitudinal macrosegregation, Cellular morphologies growing at smaller growth speeds are associated with larger amounts of macrosegregation as compared with the dendrites growing at higher growth speeds. Convection is caused, mainly, by the density inversion in the overlying melt ahead of …

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41st Rocky Mountain Conference On Analytical Chemistry Aug 1999

41st Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 41st annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-sponsored by the Colorado Section of the American Chemical Society and the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, August 1-5, 1999.

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Cell/Dendrite Distribution In Directionally Solidified Hypoeutectic Pb-Sb Alloys, S. P. O'Dell, G. L. Ding, Surendra N. Tewari Aug 1999

Cell/Dendrite Distribution In Directionally Solidified Hypoeutectic Pb-Sb Alloys, S. P. O'Dell, G. L. Ding, Surendra N. Tewari

Chemical & Biomedical Engineering Faculty Publications

The alloys Pb-2.2 wt pet Sb and Pb-5.8 wt pet Sb were directionally solidified with three different thermal gradients of 40, 86, and 140 K cm(-1) at growth rates ranging from 0.6 to 30 mu m s(-1). A Gaussian peak amplitude analysis of the cell/dendrite spacing distribution shows a distinct peak corresponding to the nearest neighbors. The peaks corresponding to the second and the third nearest neighbor spacings are also brought out by this technique. The ratios of the second to the first nearest neighbor spacings and that of the third to the first neighbor spacings are 1.85 +/-: 0.11 …

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Implementation Of Linear Array Of Ultrasonic Transmitter-Receiver Transducers For Detection Of Non-Smooth Porous Surface, Raman K. Attri, Swaranjit Singh Jul 1999

Implementation Of Linear Array Of Ultrasonic Transmitter-Receiver Transducers For Detection Of Non-Smooth Porous Surface, Raman K. Attri, Swaranjit Singh

Raman K. Attri

Level measurements, thickness measurement or remote surface detection using ultrasonic pulse transit method require that the target surface be at 90O to the incident beam so that reflected beam comes back at 180O angel to effectively use this method. This is perfectly true in case of flat, solid surface at right angle to the incident beam. But surface irregularities of a porous, non-smooth, uneven material such as snow cause penetration of incident wave into the surface, absorption of the incident energy, scatter of energy in many directions and further attenuation of reflected signal making it difficult to detect the reflected …

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Training Graduate Student Instructors Effectively: The University Of Michigan Model, Trevor S. Harding Jun 1999

Training Graduate Student Instructors Effectively: The University Of Michigan Model, Trevor S. Harding

Materials Engineering

No abstract provided.

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Development Of A Curved Layer Lom Process For Monolithic Ceramics And Ceramic Matrix Composites, Donald A. Klosterman, Richard P. Chartoff, Nora R. Osborne, George A. Graves, Allan Lightman, Gyoowan Han, Akos Bezewredi, Stan Rodrigues, Sung Pak, Gary Kalmanovich, Leon Dodin, Song Tu Jun 1999

Development Of A Curved Layer Lom Process For Monolithic Ceramics And Ceramic Matrix Composites, Donald A. Klosterman, Richard P. Chartoff, Nora R. Osborne, George A. Graves, Allan Lightman, Gyoowan Han, Akos Bezewredi, Stan Rodrigues, Sung Pak, Gary Kalmanovich, Leon Dodin, Song Tu

Chemical and Materials Engineering Faculty Publications

A novel rapid prototyping technology incorporating a curved layer building style was developed. The new process, based on Laminated Object Manufacturing (LOM), was designed for efficient fabrication of curved layer structures made from ceramics and fiber reinforced composites. A new LOM machine was created, referred to as Curved Layer LOM. This new machine uses ceramic tapes and fiber prepregs as feedstocks and fabricates curved structures on a curved-layer by curved-layer basis. The output of the process is a three dimensional "green" ceramic that is capable of being processed to a seamless, fully dense ceramic using traditional techniques. A detailed description …

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Grain Oriented Crystallization, Piezoelectric, And Pyroelectric Properties Of (Baxsr₂ - X)Tisi₂O₈ Glass Ceramics, Jianping Zhang, Burtrand I. Lee, Robert W. Schwartz, Zhenya Ding Jun 1999

Grain Oriented Crystallization, Piezoelectric, And Pyroelectric Properties Of (Baxsr₂ - X)Tisi₂O₈ Glass Ceramics, Jianping Zhang, Burtrand I. Lee, Robert W. Schwartz, Zhenya Ding

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Polar, nonferroelectric (BaxSr2 - x)TiSi2O8 glass ceramics with highly oriented crystallites were prepared by a gradient temperature heat treatment technique. The crystallization mechanism and microstructures of (BaxSr2 - x)TiSi2O8 glass ceramics were investigated by means of differential thermal analysis, x-ray diffraction and scanning electron microscopy, and the dielectric, piezoelectric and pyroelectric properties were investigated for various compositions. The results show that polar (BaxSr2 - x)TiSi2O8 glass ceramics have a low dielectric constant and a high hydrostatic figure of merit dh × gh = ~ 2500. This high hydrostatic figure of merit, along with other unique characteristics, such as no aging …

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Oxygen And Phosphorus Coordination Around Iron In Crystalline Ferric Ferrous Pyrophosphate And Iron-Phosphate Glasses With Uo₂ Or Na₂O, C. H. Booth, P. G. Allen, J. J. Bucher, N. M. Edelstein, D. K. Shuh, G. K. Marasinghe, Mevlüt Karabulut, C. S. Ray, D. E. Day Jun 1999

Oxygen And Phosphorus Coordination Around Iron In Crystalline Ferric Ferrous Pyrophosphate And Iron-Phosphate Glasses With Uo₂ Or Na₂O, C. H. Booth, P. G. Allen, J. J. Bucher, N. M. Edelstein, D. K. Shuh, G. K. Marasinghe, Mevlüt Karabulut, C. S. Ray, D. E. Day

Materials Science and Engineering Faculty Research & Creative Works

Fe K-edge x-ray absorption fine-structure (XAFS) measurements were performed on glass samples of (Fe3O4)0.3(P2O5)0.7 with various amounts of Na2O or UO2. Near-edge and extended-XAFS regions are studied and comparisons are made to several reference compounds. We find that iron in the base glass is ~25% divalent and that the Fe2+ coordination is predominantly octahedral, while Fe3+ sites are roughly split between tetrahedral and octahedral coordinations. Also, we measure roughly one FeñOñP link per iron. Substitution of Na2O or UO2 up to 15 mo1% primarily affects the first FeñO shell. The results are compared to data from the related material Fe3(P2O7)2.

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The Influence Of Heat On The Measurement Of Photocurrent At The Anodic Film Of Nickel Electrode, Hang Chen, Zhiyu Jiang May 1999

The Influence Of Heat On The Measurement Of Photocurrent At The Anodic Film Of Nickel Electrode, Hang Chen, Zhiyu Jiang

Journal of Electrochemistry

The influence of heat on the measurement of photocurrent for nickel electrode in 1 mol/L NaOH solution was investigated by using the photocurrent,photothermal and thermal current methods. It was found that the appearance of photocurrent in potential region of -0.750.20 V(vs. Hg/HgO electrode) was due to the p_type semiconductor properties of Ni(OH)2 film in which is agree with the previous report. In the Ni(OH)2/NiOOH redox potential region, the increase of temperature at the surface of working electrode during irradiation significantly promoted the electrochemical reaction strongly. The photocurrent observed in potential region 0.200.57 V is mainly attributed to the influence of …

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Effects Of Nickel Content And Simulated Heat Affected Zone Of 2205 Duplex Stainless Steel On Pitting Corrosion, Horngyih Liou, Jutung Lee, Wenta Tsai May 1999

Effects Of Nickel Content And Simulated Heat Affected Zone Of 2205 Duplex Stainless Steel On Pitting Corrosion, Horngyih Liou, Jutung Lee, Wenta Tsai

Journal of Electrochemistry

The effects of nickel content and Gleeble simulated heat affected zone(HAZ) of 2205 stainless steel on pitting corrosion were investigated in this paper. The results showed that nickel content, ranging from 4.5 wt% to 6.5 wt% in base metal, had only a minor effect on the electrochemical polarization curves, with all Enp's and Epp's falling in the rang of 1 1001200 mV. Comparing with the base metal, the simulated HAZ microstructure caused an increase in the anodic current density, a distinct decrease in both Enp and Epp , and a reduction in the passive range. Furthermore, hysteresis behavior was found …

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Investigation Of Solution Chemistry In Crevice Of Carbon Steel And Its Anodic Polarization Behavior, Zhuo Chen, Cuiwei Du, Bei Cao, Yinshun Wu, Hai Yang, Zhengrong Zhang May 1999

Investigation Of Solution Chemistry In Crevice Of Carbon Steel And Its Anodic Polarization Behavior, Zhuo Chen, Cuiwei Du, Bei Cao, Yinshun Wu, Hai Yang, Zhengrong Zhang

Journal of Electrochemistry

A self_made wedge_shaped simulated crevice apparatus was designed to investigate the solution chemistry in crevice of carbon steel and its anodic polarization behavior. For carbon steel with 3.5%(wt) NaCl , the change and the distribution of electrode potential , concentration of Cl- and pH value of solution in the crevice, and the current density of metal in the crevice were measured respectively under various conditions of anodic polarization. The results showed that without polarization the metal about 2 cm away from the opening of the crevice was attacked preferentially because of its lowest free corrosion potential. The anodic polarization promoted …

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The Adsorption Stability Of Interface Corrosion Inhibitor, Fuxing Gan, Dihua Wang, Jinyun Zou May 1999

The Adsorption Stability Of Interface Corrosion Inhibitor, Fuxing Gan, Dihua Wang, Jinyun Zou

Journal of Electrochemistry

Some new results on the adsorption stability of interface corrosion inhibitor are presented. The concept of adsorption stability and the factors influencing the adsorption stability were discussed. It is shown that the anodic desorption potential can be employed to evaluate the adsorption stability of the inhibitor as an empirical character in some conditions. Electrochemical oscillations phenomena were observed for the first time on a rotating iron electrode in H2SO4 solution containing organic inhibitor in the active potential region. These potentiostatic current oscillations can occur under cathodic polarization, as well as under anodic plarization. The oscillation period, amplitude, incubation time and …

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Study On The Hydrogen Permeation Through Zinc Electrodeposit, Jiangli Cao, Jixun Wu, Yanping Lu, Jie Shi May 1999

Study On The Hydrogen Permeation Through Zinc Electrodeposit, Jiangli Cao, Jixun Wu, Yanping Lu, Jie Shi

Journal of Electrochemistry

The electrochemical hydrogen_permeation technique was used to study hydrogen permeation through zinc electrodeposit with bilayer specimens of Fe substrate/zinc electrodeposit.The effect of coating thickness on hydrogen diffusion coefficient and hydrogen steady-state flux was studied. The results showed that hydrogen diffusion coefficient was approximately in the range of 10-11 cm2s-1 rank and zinc coating could retard hydrogen permeation. Accordingly, hydrogen steady_state flux and effective diffusion coefficient declined while the coating thickness increased.

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In Situ Ftir Spectroelectrochemical Study Of Palladium Hexacyanoferrate Thin Film Deposited On Glassy Carbon Electrode, Aili Bo May 1999

In Situ Ftir Spectroelectrochemical Study Of Palladium Hexacyanoferrate Thin Film Deposited On Glassy Carbon Electrode, Aili Bo

Journal of Electrochemistry

The electrochemically deposited Palladium hexacyanoferrate thin film on Glassy Carbon electrode (PdHCF|GC) has been studied in HCl, KCl and NaCl solutions by in_situ external reflection FTIR spectroelectrochemical technique. It is found that the behavior of the electroactive PdHCF film can be understood in terms of two states: Pd2Fe(II)(CN)6 formed in the inner layer and (M+)2Fe(II)(CN)6 (M+: electrolyte cation) formed in the outer layer. The inner layer is oxidized at Em=0.87 V in 1 mol/L KCl, while for the outer layer Em=0.77 V(vs. Ag/AgCl). In 1 mol/L NaCl or HCl solutions, half_wave potentials of these two layers are not well resolved, …

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Influence Of Ptfe And Nafion On The Utilizationefficiency Of Pt/C Catalyst In Pemfc, Xiaoliang Cheng, Baolian Yi, Jingxin Zhang, Ming Han, Yaguang Qiao May 1999

Influence Of Ptfe And Nafion On The Utilizationefficiency Of Pt/C Catalyst In Pemfc, Xiaoliang Cheng, Baolian Yi, Jingxin Zhang, Ming Han, Yaguang Qiao

Journal of Electrochemistry

With cycling voltammetry curve(C-V), TEM and SEM photographs, the influence of PTFE and Nafion on the platinum utilization in catalyst layer of PEMFC was investigated. The results show that in gas diffusion electrode, the blocking effect of PTFE in the platinum utilization is not pronunced. In the thin_film catalyst layer, the electron conduct of the catalyst was blocked by the nafion solid and this caused the decrease of platinum utilization. With the increase of the nafion content in the catalyst layer, both platinum utilization and the electron conductivity decreased in the catalyst layer. Because the molecule size of nafion is …

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Preparation And Application Of Gold_Film On The Surface Of Bacterial_Modified Carbon Paste Electrode, Rongzong Hu, Yanping Ruan, Hao Xu, Jinkun Fu, Weide Zhang, Wenyun Hu May 1999

Preparation And Application Of Gold_Film On The Surface Of Bacterial_Modified Carbon Paste Electrode, Rongzong Hu, Yanping Ruan, Hao Xu, Jinkun Fu, Weide Zhang, Wenyun Hu

Journal of Electrochemistry

A novel method for preparation of gold_film composed of ultra_fine gold particles was reported in this paper. The gold_film was prepared by electrochemical method on the surface of the paste electrode modified with the strain Bacillus sp. D01 which has strong ability to absorb and reduce Au3+. In addition, this paper reported an experimental method of determining trace amount of Cu2+ in water solution using cathodic stripping analysis to estimate the performances of the obtained gold_film. The experimental results indicated that this new method for preparation of gold_film is simple. The obtained gold_film electrode is stable and sensitive to determining …

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Effect Of Inhibitor On Electrochemical Behavior Of 1cr18 Stainless Steel In Acidic Solution Under Friction, Jinping Xiong May 1999

Effect Of Inhibitor On Electrochemical Behavior Of 1cr18 Stainless Steel In Acidic Solution Under Friction, Jinping Xiong

Journal of Electrochemistry

The electrochemical behavior of 1Cr18 stainless steel had been studied using a reciprocating triboelectrochemical equipment under friction in 0.2 mol/L H2SO4 solution with and without addition of thiourea, the frictionized surface of 1Cr18 stainless steel had been examined by the SEM, XPS and IR. The results showed that the loss rate of 1Cr18 stainless steel in the solution could be reduced by addition of thiourea. The adsorption of thiourea on the surface of 1Cr18 stainless steel prohibited the oxidization of Cr3+ to form Cr() and formation of passive film consisting of CrO42- or/and Cr(), and make the passive range to …

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Electrochemical Behavior Of Riboflavin On Glassy Carbon Electrode, Hong Li, Lincai Jiang May 1999

Electrochemical Behavior Of Riboflavin On Glassy Carbon Electrode, Hong Li, Lincai Jiang

Journal of Electrochemistry

The electrochemical behavior of riboflavin(RF) on glassy carbon has been investigated by using potential sweep,rotating ring_disc electrode and the measurement of differential capacitance. It is shown that a single well_behaved oxidation_reduction wave corresponding to a reversible two_electrons reaction apears in medium of pH<6,and the adsorption of RFH2 formed by electro_reduction is weak and hence its solubility is good.In medium of pH>6,there are two separating but overlapping partly oxidation_reduction waves corresponding to two_step one_electron reaction.The adsorptions of RFH and RFH2 produced by reduction reactions in medium of 610,the solubilities of the adsorbed species produced by electro_reduction are good.

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The Behaviors Of Capacity Loss Of Limn2o4 Cathodeat Elevated Temperatures, Xiaohong Hu, Hanxi Yang, Xinping Ai, Shengxian Li, Xinlin Hong May 1999

The Behaviors Of Capacity Loss Of Limn2o4 Cathodeat Elevated Temperatures, Xiaohong Hu, Hanxi Yang, Xinping Ai, Shengxian Li, Xinlin Hong

Journal of Electrochemistry

The capacity loss of spinel LiMn2O4 cathode at elevated temperatures was evaluated by constant current charge_discharge methods and it was found that serious capacity loss and cycleability decrease occured at above 50 , especially for the charged cells. The mechanisms for this phenomena were examined by atomic emission and infrared spectrometry of the electrolyte, XRD measurment of the cycled elecrode and microelectrode voltammetry of LiMn2O4 at room and elevated temperatures. The results showed that with increasing temperature, Mn and Li ions tended to redistribute partly in the spinel framework due to the disproportion of Mn3+ ions and this results in …

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The Influential Factors On The Triboelectrochemical Behaviors Of The Passive Alloys, Dongbai Sun, Tao Li, Hongying Yu, Dejun Yang May 1999

The Influential Factors On The Triboelectrochemical Behaviors Of The Passive Alloys, Dongbai Sun, Tao Li, Hongying Yu, Dejun Yang

Journal of Electrochemistry

The tribocorrosion process of Fe_Cr alloys with different Cr content in H2SO4 solution was investigated.The influence of applied load, friction velocity, Cr content and concentration of H2SO4 in solution on the triboelectrochemical behaviors of the alloys was analyzed. It is shown that applied load and friction velocity have singnificant influence on the tribocurrent density in passive region when friction process occurs on part of the surface of alloy.Increasing the corrosion resistance of alloys or decreasing the aggressive of the solution can reduce the alloy removal velocity.

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A Study On The Cathode Protection Potential Against Pitting Corrosion, Chunchun Xu, Youping Liu, Xiaobo Zhang, Xuhui Zhao May 1999

A Study On The Cathode Protection Potential Against Pitting Corrosion, Chunchun Xu, Youping Liu, Xiaobo Zhang, Xuhui Zhao

Journal of Electrochemistry

The methods have been developed to determine the protection potential against pitting corrosion. They are based on the theory that the pitting protection potential(Ep) is actually the transition potential of the direction of current between the occluded cell and the external surface (ET).ET lasts from -220 mV to -440 mV(SCE), the lowest of which can be considered as cathode protection potential. The Ep values determined with cyclic potentiodynamic polarization method is included in the ET with above methods.

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