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        검색결과 406

        221.
        2007.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Bulk metallic glass (BMG) composite was fabricated by consolidation of milled metallic glass composite powders. The metallic glass composite powder was synthesized by a controlled milling process using the Cu-based metallic glass powder blended with 30 vol% Zr-based metallic glass powders. The milled composite powders showed a layered structure with three metallic phases, which is formed as a result of mechanical milling. By spark plasma sintering of milled metallic glass powders in the supercooled liquid region, a fully dense BMG composite was successfully synthesized.
        4,000원
        223.
        2006.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Ni based() bulk metallic glass(BMG) powders were produced by a gas atomization process, and ductile Cu powders were mixed using a spray drying process. The Ni-based amorphous powder and Cu mixed Ni composite powders were compacted by a spark plasma sintering (SPS) processes into cylindrical shape. The relative density varied with the used SPS mold materials such as graphite, hardened steel and WC-Co hard metal. The relative density increased from 87% to 98% when the sintering temperature increased up to in the WC-Co hard metal mold.
        4,000원
        224.
        2006.09 구독 인증기관·개인회원 무료
        The shrinkage variation of Low Temperature Cofired Ceramics(LTCC) limits the size of the substrates that impose limitations on embedded passive components. This paper focuses on the method of minimizing or controlling planar shrinkage and reducing distortion during firing. The laminated sheets of alumina and glass were sintered at varying temperature, and depending on the amount of the glass ceramics. When the sintered of multi-layer structure with , the glass infiltrated entirely into layer at the temperature of about or higher.
        225.
        2006.09 구독 인증기관·개인회원 무료
        A novel sintering process is proposed for bonding of and layers. Common commercial glass was used and infilterated among filler particles. As the kind of commercial glass, the phenomenon of the infilteration is different. Although Sud-1140 glass forms a glass/filler composite, it is not completely infilterated into the filler particles at . However as the increase of sintering temperature the infilteration of glass was improved. In this study, GA-1 and GA-12 glasses were infilterated the more than Sud-1140 glass. However, they are reacted by layer. The results of the experiment show that constrained sintering and the co-firing of the different materials were possible for glass infilteration using Sud-1140 glass at .
        226.
        2006.09 구독 인증기관·개인회원 무료
        Y-type barium ferrite was prepared by the glass-ceramic method. Glasses with composition of were prepared, and the precipitation behavior of Y-type ferrite from the glass matrix was investigated by heating glass specimens at various temperature. which is a precursor of M-type ferrite was precipitated at about 813 K and an unknown compound, phase X, was precipitated at about 850 K. M-type ferrite and Y-type ferrite started to form at about 923 K and 1103 K, respectively. The formation of Y-type ferrite was int erpreted as the result of the reaction of M-type ferrite with a melt of phase X.
        227.
        2006.09 구독 인증기관·개인회원 무료
        Y-type barium ferrite ( Me=Zn, Co, Cu) expected as an electromagnetic wave absorber were prepared by the glass-ceramic method. The glasses with composition of were prepared. Single-phase powders of Y type barium ferrite were obtained with the composition . The shape of Y-type crystals depended strongly on the heating temperature and changed from a plate-like hexagon to a complex polyhedron with increasing heating temperature. Correlation was recognized between saturation magnetization and crystal shape. Electromagnetic wave absorption characteristics was affected by the saturation magnetization and crystal shape.
        229.
        2006.09 구독 인증기관·개인회원 무료
        The preparation of metallic glass composite powders was accomplished by the mechanical alloying of a pure Ti, Cu, Ni, Sn and carbon nanotube (CNT) powder mixture after 8 h milling. In the ball-milled composites, the initial CNT particles were dissolved in the Ti-based alloy glassy matrix. The bulk metallic glass composite was successfully prepared by vacuum hot pressing the as-milled CNT/ metallic glass composite powders. A significant hardness increase with the CNT additions was observed for the consolidated composite compacts.
        230.
        2006.09 구독 인증기관·개인회원 무료
        Mg55Y15Cu30 metallic glass powders were prepared by the mechanical alloying of pure Mg, Y, and Cu after 10 h of milling. The thermal stability of these Mg55Y15Cu30 amorphous powders was investigated using the differential scanning calorimeter (DSC). Tg ,Tx , and ΔTx are 442 K, 478 K, and 36 K, respectively. The as-milled Mg55Y15Cu30 powders were then consolidated by vacuum hot pressing into disk compacts with a diameter and thickness of 10 mm and 1 mm, respectively. This yielded bulk Mg55Y15Cu30 metallic glass with nanocrystalline precipitates homogeneously embedded in a highly dense glassy matrix. The pressure applied during consolidation can enhance thermal stability and prolong the existence of amorphous phase within Mg55Y15Cu30 powders.
        231.
        2006.09 구독 인증기관·개인회원 무료
        Bulk amorphous materials have been intensively studied to apply for various advanced industry fields due to their high mechanical, chemical and electrical properties. These materials have been produced by several techniques such as mechanical alloying, melt spinning and gas atomization, etc. Among them, the atomization is the most potential technique for commercialization due to high cooling rate during solidification of the melt and mass productivity. However, the amorphous powders still have some limitations because of their low ductility and toughness. Therefore, intensive efforts have to be carried out to increase the ductility and toughness. In this study, the Ni-based amorphous powder was produced by the gas atomization process. And in order to increase the ductile toughness, ductile Cu phase was coated on the Ni amorphous powder by spray drying process. The characteristics of the as-synthesis powders have been examined and briefly mentioned. The master alloy with Ni57Zr20Ti16Si2Sn3 was prepared by vacum induction melting furnace with graphite crucible and mold. The atomization was conducted at 1450oC under the vacuum of 10-2 torr. The gas pressure during atomization was varied from 35 to 50 bars. After making the Ni amorphous powders, the spray drying was processed to produce the Cu -coated Ni amorphous composite powder. The amorphous powder and Cu nitrate solution were mixed together with a small amount of binder and then it was sprayed at temperature of 130oC and rotating speed of 15,000 R.P.M..
        232.
        2006.09 구독 인증기관·개인회원 무료
        Bulk metallic glass (BMG) composites combining a Cu54Ni6Zr22Ti18 matrix with brass powders or Zr62Al8Ni13Cu17 metallic glass powders were fabricated by spark plasma sintering. The brass powders and Zr-based metallic glass powders added for the enhancement of plasticity are well distributed homogeneously in the Cu-based metallic glass matrix after consolidation. The BMG composites show macroscopic plasticity after yielding, and the plastic strain increased to around 2% without a decrease in strength for the composite material containing 20 vol% Zr-based amorphous powders. The proper combination of strength and plasticity in the BMG composites was obtained by introducing a second phase in the metallic glass matrix.
        235.
        2006.04 구독 인증기관·개인회원 무료
        A porous material with a surface layer was fabricated using glass abrasive sludge and expanding agents. The glass abrasive sludges were mixed with expanding agents and compacted into pellets. These pellets were sintered in the range of for 20min. The sintered porous materials had a surface layer with smaller pores and inner parts with larger pores. The surface layer and pores controlled the absorption ratio and physical properties.
        236.
        2006.04 구독 인증기관·개인회원 무료
        Fabrication of a nano-laminar ceramic composite by sintering thin ceramic plates was examined. Silver-coated glass flakes with a thickness of less than were consolidated by pulsed current sintering or hotpressing to obtain model composites. The samples sintered at the optimum conditions were fairly dense, and the flakes were aligned by uniaxial press. The metal coating remained on the flakes through the sintering process, and became an interface layer between the flakes. No crack propagation through the transverse direction of the lamellar was observed in the indentation test. The possibilities of high resistance against crack propagation was suggested.
        237.
        2006.04 구독 인증기관·개인회원 무료
        NiTiZrSiSn bulk metallic glass powder was produced using inert gas atomization and then was sprayed onto a SS 41 mild steel substrate using the kinetic spraying process. Through this study, the effects of thermal energy of in-flight particle and crystallization degree by powder preheating temperature were evaluated. The deformation behavior of bulk metallic glass is very interesting and it is largely dependent on the temperature. The crystalline phase formation at impact interface was dependent on the in-flight particle temperature. In addition, variations in the impact behavior need to be considered at high strain rate and in-flight particle temperature.
        239.
        2006.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
          The high degree of viscosity and the non-Newtonian fluid dynamics characterizes the process inside a glass furnace. Because the temperature is fluctuating in very short time-intervals, it is hard to determine that the status of its fluctuation is stable
        3,000원