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        검색결과 66

        21.
        2008.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Fe based () amorphous powder were produced by a gas atomization process, and then ductile Cu powder fabricated by the electric explosion of wire(EEW) were mixed in the liquid (methanol) consecutively. The Fe-based amorphous - nanometallic Cu composite powders were compacted by a spark plasma sintering (SPS) processes. The nano-sized Cu powders of 200 produced by EEW in the methanol were mixed and well coated with the atomized Fe amorphous powders through the simple drying process on the hot plate. The relative density of the compacts obtained by the SPS showed over 98% and its hardness was also found to reach over 1100 Hv.
        4,000원
        22.
        2008.07 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Nano-sized TiO2-60 wt% SrO composite powders were synthesized by a sol-gel method using titanium isopropoxide and Sr(OH)2 · 8H2O as precursors. 3, -5, -7 wt%Ag spot-coated TiO2-60 wt% SrO composite powders were synthesized by a Ag electroless deposition method using TiO2-60 wt% SrO composite powders calcined at 1050˚C, which mainly exhibited the SrTiO3phase. However, a small number of rutile TiO2, Sr2TiO4 and SrO2 phases were also detected. In the Ag spot-coated powders synthesized by electroless deposition, nano-sized particles about 5-25 nm in diameter adhered to the TiO2-60 wt% SrO composite powders. The photocatalytic activity of Ag spot-coated TiO2-SrO and TiO2-SrO composite powders for degradation of phenol showed that all of TiO2-SrO composite powders were highly active under UV light irradiation. 7 wt%Ag spot-coated TiO2-60wt.%SrO composite powders had a relatively higher photocatalytic activity than did TiO2-SrO composite powders under visible light.
        4,000원
        23.
        2008.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Silver coated copper composite powders were prepared by electroless plating method by controlling the activation and deposition process variables such as feeding rate of silver ions solution, concentration of reductant and molar ratio of activation solution at room temperature. The characteristics of the product were verified by using a scanning electron microscopy (SEM), X-ray diffraction (XRD) and atomic absorption (A.A.). It is noted that completely cleansing the copper oxide layers and protecting the copper particles surface from hydrolysis were important to obtain high quality Ag-Cu composite powders. The optimum conditions of Ag-Cu composite powder synthesis were molar ratio 4, concentration of reductant 15g/l and feeding rate of silver ions solution 2 ml/min.
        4,000원
        24.
        2007.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Characteristics of Al-based composites with waste stainless steel short fiber, fabricated by magnetic pulsed compaction and sintering were investigated. The compacts prepared by magnetic pulsed compaction showed high relative density and homogeneous microstructure compared with that by conventional press compaction. The relative density of sintered composites at for 1 h exhibited the same value with compacts and decreased with increase in STS short fiber content. The reaction between Al and STS phase was confirmed by the microstructural analysis using EDS. The sintered composites, prepared by magnetic pulsed compaction, showed increased hardness value with increasing STS fiber content. Maximum yield strength of 100 MPa and tensile strength of 232 MPa were registered in the AI-based composite with 30 vol% STS short fiber.
        4,000원
        25.
        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
        26.
        2006.09 구독 인증기관·개인회원 무료
        Particles of high strength material when coated with silver offer a means of obtaining desirable electrical properties and high strength. The coating process employed aqueous ammoniacal silver-nitrate electrolytes with a formaldehyde solution as the reductant. Modifying additives were also applied. The reduction and subsequent deposition of silver occurred selectively on the surface of the tungsten particles. The morphologies of the coated particles were assessed by SEM imaging. The silver was uniformed coated on tungsten powder and its thickness was estimated to be approximately 100nm on the basis of a mass account.
        29.
        2006.04 구독 인증기관·개인회원 무료
        Nano-sized WC particles in WC/Co composite powders were synthesized by mechanochemical method. The raw powders and graphite) were mixed by planetary milling for 30 hours. The compositions were WC-10 and -20 wt% Co added VC and . The direct reduction and carburization of the mixed powders were carried at for 1 to 3 hours under flowing Ar gas. The mean size of WC particles in WC/Co composite powders was about 16 nm. The resultant powders were compacted and sintered at for 0.5 hour. After sintering the mean size of WC particles was about 50 nm.
        30.
        2006.04 구독 인증기관·개인회원 무료
        The free sintering of metallic powders blended with non sintering inclusions is investigated by the Discrete Element Method (DEM). Each particle, whatever its nature (metallic or inclusion) is modeled as a sphere that interacts with its neighbors. We investigate the retarding effect of the inclusions on the sintering kinetics. Also, we present a simple coarsening model for the metallic particles, which allows large particles to grow at the expense of the smallest.
        33.
        2005.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The silica nanoparticles were used as support of catalyst, filling material, electronic assembler, thin film material, and sensor material. And, the titania nanoparticles were used as pigment, dielectric substance, sensor and photocatalyst. In this paper, the spherical composite particles of TiO2/SiO2with narrow size distribution and phase pure were synthesized by ultrasonic spray pyrolysis method from TiOSO4 and colloidal silica solution. Using ultrasonic apparatus, this starting solution was vaporized to droplets, and these droplets were induced into tube furnace by carrier gas. The resulting composite powder was characterized by scanning electron microscopy, X-ray diffraction analysis, TG-DTA, in vitro sun protection factor(SPF) and BET surface area analysis.
        4,000원
        39.
        2004.06 구독 인증기관·개인회원 무료
        The microstructure and mechanical properties of the hypereutectic prealloyed Al-Si powders prepared by the gas atomization process were described in this paper. With increasing the gas pressure of the atomization, the average powder size was decreased from about . The primary eutectic Si particles were uniformly distributed in the Al matrix and their size varied in the range of . The high densified specimens with above 96% of the theoretical density were fabricated the hot pressing process. The UTS mechanical properties of VN1 specimens were much higher than that of conventional hypoeutectic Al-Si alloys.
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