Papers by Keyword: Conductivity

Abstract: Non-continuous nano-silver layer deposited on the PET filament by the use of vacuum sputtering technology and then become continuous with the help of newly electroless spray plating process.The functionality and durability of the Silver-coated PET filament was tested and analyzed. The results showed that it has good electrical conductivity. With the weight increasing goes up, the electrical conductivity increases obviously,then prone to slow increment .

Abstract: This paper described the characteristics of open virtual equipment platform LabVIEW, and introduced the method to construct data collecting system using this platform. And developed computer controlled monitoring unit of magneto-rheological grease conductivity, tested the relation between magneto-rheological grease conductivity and external magnetic field, particle concentration, and thickness of magneto-rheological grease. In windows system, the virtual instrument constructed by using LabVIEW programming implemented the real time measurement, display, record of conductivity output, analysis its conductivity characteristics, and fitted the output electric resistance data and determined the best fitting curve. The experiment certified that this method doesn't need complex programming, reduces the programming time, and simplifies the development procedure, and increases the flexibility of detection system.

Abstract: Different compositions of surfactant systems give rise to a rich variety of structures of aggregates. At higher concentrations of surfactant in water, the surfactant molecules aggregate to form lyotropic liquid crystals [1]. In the present work we have prepared two surfactant systems consisting of (i) 20% of cetyl-trimethyl-ammonium-bromide (CTAB) in water, and (ii) 30% of tetra-decyl-trimethyl-ammonium-bromide (TTAB) in water. Both the systems exhibit various lyotropic liquid crystal structures when an increasing amount of co-surfactant is added as third component [2, 3]. These liquid crystalline structures are very sensitive to the solution conditions such as co-surfactant concentration, temperature, ionic strength, counter ion polarizability etc. In this study, positron life time spectroscopy and conductivity measurement have been employed to locate various phases exhibited by the lyotropic liquid crystals. In addition to delineating various phase boundaries of the systems, positron annihilation technique has also yielded new findings.

Abstract: In order to reduce the conductivity of power-station’s circulating cooling water and reduce sewage discharge, this essay does research on using electro sorption technology to replace traditional water treatment technology. Through exploring the voltage and flow of the working module from experiment, it determined the optimum working conditions for electro sorption. The experiment includes the efficiency of reducing inlet water conductivity at different voltages, and the effect of flow rate to the treatment, proving that water conductivity will drop from 3,000 to 700 μS/cm on the condition of 1.7 V voltage and 500 L/h flow rate, which makes great sense to Electro sorption industrial applications.

Abstract: Calcia-stabilized zirconia (CSZ) sensor elements of 8 and 16 mol% was synthesized by mixing appropriate amounts of Calcia and Zirconia using in agate mortar and pestle followed by sintering at 1500°C for 3 hours. The electrical conductivity of the stabilized zirconia was measured at different temperature using the two probe impedance analyzer in the temperature range 150°C to 500°C. It was found that the calcia influences the grain boundary thickness. The conductivity is discussed in terms of the ionic vacancies in the bulk due to calcium ion substitution and the available grain boundary path.

Abstract: Cu-Cr contact material is used in medium voltage, high current vacuum interrupters. Vacuum interrupter is the heart of Vacuum Circuit breaker. Contact tips are usually made using powder metallurgical techniques in disk shape. These disks are machined to required dimensions and then hermitically sealed by vacuum brazing. The properties of the final contact tips are thus usually rarely studied. In the present study the properties before and after the vacuum sealing are compared in order to establish a correlation between them. The Cu-Cr contact tips were made under different compaction pressures, sintering temperatures and soaking time periods. Cu-Cr contacts were prepared by powder processing route and sintering in vacuum furnace at the temperatures of 1050°C for different soaking time period of 4, 6 and 8 Hrs. The samples were then subjected to simulated sealing cycle at temperatures (870 and 960°C). The electrical conductivity, hardness, microstructure and grain morphology of all the samples were studied. Properties of as-sintered and after sealing were analyzed and compared. The results of quantitative microscopy shows the better result on sintered sample soaked for 4 Hrs. The hardness and conductivity of the sample without brazing, varies between 79.9 - 83.8 HRF and 37.9 - 43.1% IACS respectively. The hardness and conductivity of the brazed sample varies between 52.5 - 63.42 HRF and 48.32 - 51.33 %IACS respectively.

Abstract: In the present work we have used Physical vapour deposition (PVD) technique followed by thermal annealing to synthesize Ag-soda glass nanocomposite samples. This technique offers a great deal of promise in terms of general simplicity of operation, minimal requirements for sample preparation, ease of adaptation to automated operation, and potential for scale up to production levels of material throughput. Ag-glass nanocomposites were synthesized by deposited Ag on glass slides and the resulting samples were annealed in air at various temperatures from 400 °C to 550 °C for 1 hour. Optical absorption spectrum of the resulting nanocomposites was measured in the range from 190 nm to 900 nm using UV-Visible absorption spectroscopy. The appearance of SPR peak characteristic of Ag nanoparticle formation around 420 nm in optical spectra of annealed samples indicates towards the formation of silver nanoparticles in soda glass. The size of silver nanoparticles has been found to increase with increase in annealing temperatures. Structural properties of resulting nanocomposites were also studied using TEM and FE-SEM alongwith EDAX spectra. Synthesized composites are more conducting than pristine glass and conductivity increases with increase in size of Ag nanoparticles embedded in glass. Possible mechanism for increase in conductivity has been discussed.

Abstract: Strengthening process tests were carried out on the CuNiBeZrSi alloy used for slot wedge in turbo-generator rotor. By EM, XRD anasys ，The results show that: in this experimental conditions, to obtain better overall performance, the heat treatment process of slot wedges copper alloy is: forging - water quenching solution-aging. CuNiBeZrSi alloy got a better overall performance after solid solution 950°C×1.5h+460°C×3h aging. And the values of hardness and electrical conductivity of the alloy are HB 259 and 56 %IACS. It can meet the requirement of slot wedge copper alloy working, with better economic benefits.

Abstract: Nanoscale Nickel ferrite particles were prepared by combustion method using nickel nitrate as oxidizer and urea as a fuel. The structure of the sample is studied with X-ray diffraction (XRD) using Cu-Kα radiation. The X-ray diffraction analysis revealed the nanocrystalline nature in the prepared ferrite samples. Dielectric studies have been undertaken over a wide range of frequencies (100Hz-5MHz) for Nickel nanoferrites at room temperature. Dielectric properties such as dielectric loss tangent (D), dielectric constant (ε′ ) and dielectric loss factor (ε″) are found to decrease with the increase in the frequency. Observed variations are understood on the basis of Koop’s phenomenological model. Further, a. c. conductivity of the Nickel nanoferrite was found to increase with the increase in the frequency. Observed variation in the a. c. conductivity with the frequency has been understood on the basis of electron hopping model.

Abstract: The magnetorheological fluid is a new smart material. its mechanical properties has been widely known .Under the influence of a magnetic field ,the apparent viscosity of magnetorheological fluid will increase by two orders of magnitude . To verify magnetorheological fluid would have a similar change in the electrical and thermal conductivity, some testing have been done and concludes that under the different magnetic field the conductivity of magnetorheological is variational . At some extend, the stronger the magnetic field the better the electrical and thermal conductivity of magnetorheological fluid. A theoretical explanation for this phenomenon has been given.