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        검색결과 553

        303.
        2006.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, high purity fine powders were prepared by SHS (Self-propagating High-temperature Synthesis). We would examinate the study of sintering properties and characteristics as a function of temperature with various additives (binder, sintering agent). In separately binder addition, the green and sintered density of specimen were increased as binder content increases. The increased porosity resulted in fine grain size due to the inhibition of grain boundary moving. The and MgO playa role of increasing dielectric constants at room temperature. These values were decreased at curie temperature. In case of , the Curie temperature was decreased. In this study, a high dielectric ceramic capacitor material with temperature stability was synthesized by using various additives
        4,000원
        307.
        2005.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The synthesis and consolidation of titanium silicide by electro-discharge-sintering has been investigated. As-received Ti powder was in flaky shape and the mean particle size was , whereas the mean particle size of the pre-milled Si powder with angular shape was . Single pulse of 2.5 to 5.0 kJ/0.34g-elemental Ti and pre-milled Si powder mixture with the composition of Si was applied using capacitor. The solid with phase has been successfully fabricated by the discharge with the input energy more than 2.5kJ in less than Hv values were found to be higher than . The formation of occurred through a fast solid state diffusion reaction.
        4,000원
        308.
        2005.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The with various phases were prepared by simple ex-situ hydrolysis and spark plasma sintering (SPS) process of Al powder. The nano bayerite phase was derived by hydrolysis of commercial powder of Al with micrometer size, whereas the bohemite (AlO(OH)) phase was obtained by hydrolysis of nano Al powder synthesized by pulsed wire evaporation (PWE) method. Compaction as well as dehydration of both nano bayerite and bohemite was carried out simultaneously by SPS method, which is used to fabricate dense powder compacts with a rapid heating rate of per min. under the pressure of 50MPa. After compaction treatment in the temperature ranges from , the bayerite and bohemite phases change into various alumina phases depending on the compaction temperatures. The bayerite shows phase transition of sequences. On the other hand, the bohemite experiences the phase transition from AlO(OH) to It shows AlO(OH) sequences. The compacted at shows a high surface area .
        4,000원
        309.
        2005.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study the nanostructured ceramics have been fabricated by the combined application of magnetic pulsed compaction (MPC) and subsequent spark plasma sintering (SPS), and their density and hardness properties were investigated. The prepared by the combined processes showed an increase by in density, approaching the value close to the true density, and an enhancement by in hardness, compared to those fabricated by MPC or static compaction method followed by sintering treatment.
        4,000원
        310.
        2005.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Porous and porous surfaced Ti-6Al-4V implant compacts were fabricated by electro-discharge-sintering (EDS) of atomized spherical Ti-6Al-4V powders with a diameter of , The solid core formed in the center of the compact after discharge was composed of acicular Widmanstatten grains, The hardness value at the solid core was much higher than that at the particle interface or particles in the porous layer, which can be attributed to both heat treatment and work hardening effects induced from EDS, The compressive yield strength was in a range of 19 to 436 MPa which significantly depends on both input energy and capacitance, Selected porous-surfaced Ti-6Al-4V implant compacts with a solid core have much higher compressive strengths compared to the human teeth and sintered Ti dental implants.
        3,000원
        311.
        2005.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Implant prototypes with various porosities were fabricated by electro-discharge-sintering of atomized spherical Ti-6Al-4V powders. Single pulse of 0.75 to 2.0 kJ/0.7 g-powder, using 150, 300, and capacitors was applied to produce a fully porous and porous surfaced implant compact. The solid core formed in the center of the compact after discharge was composed of acicular grains and porous layer consisted of particles connected in three dimensions by necks. The solid core and neck sizes increased with an increase in input energy and capacitance. On the other hand, pore volume decreased with increased capacitance and input energy due to the formation of solid core. Capacitance and input energy are the only controllable discharge parameters even though the heat generated during a discharge is the unique parameter that determines the porosity of compact. It is known that electro-discharge-sintering of spherical Ti-6Al-4V powders can efficiently produce fully-porous and porous surfaced Ti-6Al-4V implants with various porosities in a short time less then 400 isec by manipulating the discharging condition such as input energy and capacitance including powder size.
        4,000원