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Articles 781 - 790 of 790

Full-Text Articles in Engineering Science and Materials

A Photoelectrochemical Investigation Of Zirconium Oxide Film, Maizhi Yang, Ping Wei, Di Quarto F., Piazza S., Sunseri C. Feb 1995

A Photoelectrochemical Investigation Of Zirconium Oxide Film, Maizhi Yang, Ping Wei, Di Quarto F., Piazza S., Sunseri C.

Journal of Electrochemistry

A photoelectrochemical investigation has been carried out on zirconium initialoxide film and its oxide film grownanodically at constant rate up to different thickness. Both anodicand cathedic photocurrents on the photocurrent spectrum depended on the potential, but had littlerelation with the forming anedic films or measuring solutions. Photocurrent spectrum and photocurrenttransients suggested that the oxide films on zirconium were duplex layers structure. The internal layerwas ZrO2 and the external layer ZrO2·(H2O)n. The photocurrent included photogenerated carrier ininternal and external oxide films, as well as internal photoinjection process for electrons from thesubstrate metal into the …

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Synthesis Of LiXCoo2 And Its Behaviour In Rechargeable Lithium Battery, Mingfeng Guo, Ruimin Yang, Zebo Zhang, Jincao Ye Feb 1995

Synthesis Of LiXCoo2 And Its Behaviour In Rechargeable Lithium Battery, Mingfeng Guo, Ruimin Yang, Zebo Zhang, Jincao Ye

Journal of Electrochemistry

The Variations of crystal lattice parameters of LixCoO2 during charge anddischarge have been st ud ied by XRD and AAR spectroscopy. It was found that the LixCoO2 crystalvolume expanded during charge and contracted during discharge. The crystal lattice structure was broken because of the formation of Co3O4 when deeply charge.The variation of lattice parameter C0 value in cycling process was similar to that in charge process.The variation of 006 peak was the mostsensitive in every case. In case of preheating for 20 hours at 700℃ before operating high temperature, the …

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Electroreduction Of The Nittobenzene On Titanium Electrode Implanted With Palladium, Zhongda Wu, Xianjun Zhu, Hongsen Wang Feb 1995

Electroreduction Of The Nittobenzene On Titanium Electrode Implanted With Palladium, Zhongda Wu, Xianjun Zhu, Hongsen Wang

Journal of Electrochemistry

The titanium substrates were bombarded with 1×1017～5×1017 ions·cm-2 ofpalladium at the room temperature. The surface composition of implanted electrode and concentration-depth profiles of various elements were measured by AES. The electrored uction processes ofnitrobenzene (NB) in 0.1 mol/L NaOH solution at Pd/Ti electrodes have been investigated by cyclicvoltaivimetry. The results show that the palladium implanted titanium electrodes exhibit a high catalyticactivity in the electroreduction of NB. The NB radical anion, which is the product of one-electronelectroreduction of NB, was detected by ESR in-situ in conjunction with electrochemical methods. Aniline was also detected as a product of …

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Electroreduction Of Holmium Ion On Iron Electrde In Molten Cholorides, Qiqin Yang, Guankun Liu, Yuzhi Su Feb 1995

Electroreduction Of Holmium Ion On Iron Electrde In Molten Cholorides, Qiqin Yang, Guankun Liu, Yuzhi Su

Journal of Electrochemistry

The cyclic voltammetry, open circuit potential-time curve after poteritiostatic electrolysis, current-time curve at potential step, X-ray diffraction and electron probe microanalysiswere used to investigate the electrode process of Ho(Ⅲ) reduced on iron electrode in molten chloridesand the phases of surface alloy layer. The Ho-Fe alloys are formed at first, and then the metallic holmium is deposited when Ho(Ⅲ) is reduced on iron electrode. The charge transfer is reversible. The free energies of formation for the four inter metallic compounds of Ho-Fe system, the diffusion coefficients and diffusion activation energy of Ho in alloyed cathode are determined.

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Electrocatalytic Oxidation Of Formaidehyde And Formic Acid On A Pt/SbAd Electrode, Hong Li, Lincai Jiang, Xiong Jiang Feb 1995

Electrocatalytic Oxidation Of Formaidehyde And Formic Acid On A Pt/SbAd Electrode, Hong Li, Lincai Jiang, Xiong Jiang

Journal of Electrochemistry

The electrocatalytic activity for the oxidation of formaldehyde and formic acid ona Sb-modified platinum (Pt/Sbad) was investigated. Results showed that the Pt/Sbad electrode was electrocatalytically more active than a Pt electrode in the anodic oxidation of formaldehyde and formicacid. In the case of formaldehyde, an oxidation peak appeared at a potential of ca. 0.7V. During the oxidation of formic acid, a 4-fold increase in the 1st peak current was observed. The Sb-modified platinum electrode was found to be most electrocatalytically active at a coverage of 0.75±0.05. The electrocatalytic activity of the Pt/Sbad electrode can be best …

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The Study Of The Growth Processes Of The Oxides On Lead Electrodes In Sulfuric Acid Solution, Hesheng Zhai, Xuguang Chen, Jinkua You, Yong Yang, Zugeng Lin Feb 1995

The Study Of The Growth Processes Of The Oxides On Lead Electrodes In Sulfuric Acid Solution, Hesheng Zhai, Xuguang Chen, Jinkua You, Yong Yang, Zugeng Lin

Journal of Electrochemistry

The growth processes of PbO and PbO2 on lead electrodes have been investigatedby using in-situ methods that are combined with temporary AC resistance measurment technique and in-situ laser scanning photoelectrochemical microscopy. It is found that a linear relationship existsbetween the electrode resistance(R) and1/2 after the electrode is oxidized at +0.6 V(vs.Hg/H2SO4/35% H2SO4) for more than 5 min. This result suggests that the growth of PbO is well distributed during the early stage of oxidation. The study by using laser scanning photoelectrochemical microscopy has further proved this point. The results also …

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Design Approach For Small Scale Continuous, Steady State Plants, O Kaunde Dec 1994

Design Approach For Small Scale Continuous, Steady State Plants, O Kaunde

Tanzania Journal of Engineering and Technology (TJET)

One of the major steps in the design of a process plant is development of an appiopriate flowsheet. At this step, the technical solutions may be con- sidered in relation to the social and economic factors. In this paper, guide- lines for developing a flowsheet for continuous, steady State process in a developing country environment have been proposed. To illustrate the pro- posed guidelines, a case study involving design of an ethanol distillation plant has been used.

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Improved Heat Transfer By Means Of Steam Injection In A Shell & Tube Heat Exchanger, O Kaunde Dec 1994

Improved Heat Transfer By Means Of Steam Injection In A Shell & Tube Heat Exchanger, O Kaunde

Tanzania Journal of Engineering and Technology (TJET)

When designing a heat exchanger; one aims at attaining high heat transfer rates SO as to minimise heat transfer area and therefore the overall cost. This paper presents a method of improving the overall heat travsfer coef- ficient of a conventional shell and tube heal exchanger. The method in- volves injecting steam into the process fluid as it enters the heat exchanger thus effecting mixing of fluid as it travels along the exchanger Tests car- • ried out using this technique showed a significant increase in the overall heat transfer coefficient values.

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Influence Of Arc Discharge Duration On Turbulent Mass Burning Rate, E Mushi Dec 1994

Influence Of Arc Discharge Duration On Turbulent Mass Burning Rate, E Mushi

Tanzania Journal of Engineering and Technology (TJET)

The influence of arc discharge duration on turbulent mass burning rate was investigated for turbulent r.m.s vglocities of u '=1.73 m/s and u'=4.5 nfs. Methane air mixtures were used at equivalence ratios ranging from 0.83 to / .25. Flame size was obtained through schiieren photography while the intensity Of CH chemiluminescence emissions was used to measure mass burning rate. A variable spark duration unit was used for ignition sparks and all the experiments were done in a fan stirred bomb. Discharge duration has no effect when the equivalence ratio is I. For higher values longer duration inoeases the burning rate …

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Thermodynamics And Transport Proper- Ties Analysis Of Natural Gas From Songosongo In Kilwa- Tanzania, G Mrema Dec 1993

Thermodynamics And Transport Proper- Ties Analysis Of Natural Gas From Songosongo In Kilwa- Tanzania, G Mrema

Tanzania Journal of Engineering and Technology (TJET)

Analysis ofthermodynamics and transport properties was carried outfor six natu- ral gas samples from Songosongofield in Kilwa - Tanzania using PRO/II simula- for. Properties of most interest in gas processing (due to their influence on the sales value) such as density, specific gravity, critical parameters, bubble point and dew point, enthalpy, latent heat of vaporisation, molecular weight, boiling point and phase were investigated. In addition composition of the gas was com- pared with that from elsewhere. The gas was assumed to be at a temperature of 30C and a pressme of 150 bar before pressure let down station. Results indicated …

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