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Synthesis of VIB Group Metals Silicides Dispersed Powders by Electrolysis of Halide-Oxide Melts

Journal of Chemistry and Chemical Engineering 2016年第1期10卷 7-12页

作者： Liliia Molotovska Dmytro Shakhnin Natalia Uskova Ganna Nikulina vladymyr cherednik Serge Stukota Viktor Malyshev Department of Physical Chemistry of lonic Liquids V. I. Vernadsky Institute of General and Inorganic Chemistry National Academy of Sciences of Ukraine 32/34 Palladina Ave. Kyiv 03142 Ukraine Faculty of Engineering & Technology University of Ukraine 23 L vivska St. Kyiv 03115 Ukraine

Study of electrochemical behavior of chromium (molybdenum, tungsten) and silicon containing melts allowed defining conditions for synthesis of silicides of chromium, molybdenum and tungsten in the form of fine powders by electrolysis of halide-oxide melts. Sequence of stages of electrosynthesis of silicides of molybdenum and tungsten was found as follows: deposition of more electropositive metal (molybdenum or tungsten), deposition of the second component (silicon) on the surface of metal deposited previously, and reaction diffusion of silicon into the deep of the metal-salt "pear" with the formation of silicide phases of different compositions up to the higher silicides. In contrast, during the electrodeposition of chromium silicides, one of the components (chromium) is deposited not in elemental form, but in oxide form, and the other (silicon) acts as a reducing agent for this oxide to form binary compounds. Duration of the synthesis first stage (deposition of refractory metal or of its oxide) depends on the refractory metal compound content in the system and on the cathode current density. Synthesis of silicides is possible due to retention of powders of molybdenum (tungsten) or chromium oxide at the cathode without scaling. Optimal values of concentrations ratio, current density, temperature, and duration of electrosynthesis were found. Phase composition of products were obtained, as well as their chemical and thermal stability, were studied.

关键词：金属硅化物氧化物电解合成条件粉末融化阴极电流密度电沉积过程分散

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Simulation, Fabrication and Tests of a GPS Antenna on the Roof-Top of an Automobile

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Journal of Electromagnetic Analysis and Applications 2012年第12期4卷 504-512页

作者： Margarita Tecpoyotl-Torres Jose G. Vera-Dimas Gustavo Urquiza Beltrán L. Cisneros-Villalobos vladymyr Grimalsky Svetlana V. Koshevaya Centro de Investigación en Ingeniería y Ciencias Aplicadas Universidad Autónoma del Estado de Morelos Cuernavaca Mexico.

It is very important for the car users to have several communication systems and many antennas, which respond to the demands of aesthetics and efficiency. In this case, it is necessary to consider different types of materials and geometries. Among the automobile systems, the navigation systems are found, which are formed by a Global Position System (GPS), with a pre-charged base of maps and highways in order to locate the vehicle. For the reception of the GPS signals, circularly polarized patch antennas are used, which must be designed to operate at 1.57 GHz. This work is focused on the analysis of a circular antenna performance, designed for GPS, by means of the simulation of the following cases: antenna without radome, antenna with acrylic radome, and, finally, antenna on the roof of an automobile, considering the effect of the complete chassis. A Basic, a Simplified and a More Simplified Advanced Car Models (BCM, SACM, and MSACM) were used in order to analyze the chassis shape. The simulations were carried out with the software FEKO. The fabrication and experimental and practical tests are also presented.

关键词： Car Model Circular Polarization Patch Antennas Rogers RT/Duroid 5880

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