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        검색결과 745

        349.
        2006.04 구독 인증기관·개인회원 무료
        Synthesis of zinc oxide nanorods, sheets and flower like structure were done by the sol-gel method using zinc acetate dihydrate and sodium hydroxide at with 12 hours refluxing time nanorods, in case of as synthesized powder, with diameter of 20-60nm. Annealing at higher temperature (300 and ,) in air ambient changes the morphology to sheet and flower like structure. The standard peak of zinc oxide was observed in IR at . The UV-VIS spectroscopy of zinc oxide shows a characteristic peak at 375nm.
        350.
        2006.04 구독 인증기관·개인회원 무료
        In this paper, we show some experimental results of binder-free WC sintered by Pulsed Electric Current Sintering (PECS) also known as Field Assisted Sintering Technology (FAST). These binder-free WC have extremely hardness and stiffness. However, these mechanical properties are dependent on the sintering condition, e.g., maximum temperature, applied pressure, etc. We show some relationship between mechanical properties and sintering condition to improve to sinter the binder-free WC.
        351.
        2006.04 구독 인증기관·개인회원 무료
        This work presents mechanical properties and corrosion resistance of duplex stainless steels obtained through powder metallurgy starting from austenitic, martensitic powders by controlled addition of alloying elements in the right quantity to obtain the chemical composition of the structure similar to biphasic one. In the mixes preparations the Schaffler's diagram was taken into consideration. Prepared mixes of powders have been sintered in a vacuum furnace with argon backfilling. After sintering rapid cooling was applied using nitrogen. Corrosion properties have been studied through electrochemical methods in 1M NaCl.
        355.
        2006.04 구독 인증기관·개인회원 무료
        The corrosion performance of a powder metallurgical aluminum alloy in aeronautical environments was studied for both as sintered and heat treated states. Sintered samples were obtained by uniaxial pressing of an Al-Cu-Mg prealloyed powder followed by liquid phase sintering. The heat treatments applied were T4 and T6. Corrosion behaviour was assessed by means of potentiodynamic polarization. Results for the equivalent commercial wrought counterpart, AA2024-T3, are also presented for comparison. Similar corrosion performance was observed for both as sintered and AA2024-T3 samples, while corrosion resistance of the PM materials was improved by the heat treatment, especially in the T4 state.
        356.
        2006.04 구독 인증기관·개인회원 무료
        In the present work, the sintering behavior of high strength Al-5.6Zn-2.5Mg-1.6Cu (in wt.%) alloy compacts prepared from elemental powders was investigated. Microstructural evaluation was accompanied by XRD and DSC methods in order to determine the temperature and chemical composition of the liquid phases formed during sintering. It was found that three transient liquid phases are formed at 420, 439 and 450 . Microstructural study revealed the progressive formation of sintered contacts due to the presence of the liquid phases, although the green compact expands as a result of the melt penetration along the grain boundaries. While Zn melts at , the intermetallic phases formed between Al and Mg were found to be responsible for the formation of liquid phase and the dimensional change at higher temperatures.
        357.
        2006.04 구독 인증기관·개인회원 무료
        The MIM technology is an alternative process for fabricating near net shape components that usually uses gas atomised powders with small size (< 20 μm) and spherical shape. In this work, the possibility of changing partially or totally spherical powder by an irregular and/or coarse one that is cheaper than the former was investigated. In this way, different bronze 90/10 components were fabricated by mixing three different types of powder, gas and water atomised with different particle sizes, in order to evaluate how the particle shape and size affect the MIM process.
        358.
        2006.04 구독 인증기관·개인회원 무료
        The horizontal high energy rotor ball mill () is used to break and activate dry solids. It is used for dry-milling and in the vertical mount for wet-milling in leaching processes. Technical electric arc furnace (EAF) dust with high contents of zinc oxide, zinc ferrite and magnetite is efficiently separated by ambient temperature leaching. The process shows promise for industrial application
        360.
        2006.04 구독 인증기관·개인회원 무료
        Nd-Fe-B type powder was sintered using spark plasma sintering method. Fabricated compact sintered at the temperature of , is found to be a composite magnet with Nd-Fe-Co-B and . The compact sintered at shows slightly low coercivity and large remanent magnetization comparing to the compact sintered at due to the formation of phase, resulting in the large maximum energy product. Maximum energy product tends to decrease with decreasing thickness of sintered compacts below 0.5 mm in thickness.