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        검색결과 4

        1.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Nano-sized was in situ synthesized in copper matrix through self-propagating high temperature synthesis (SHS) with high-energy ball milled Ti-B-Cu elemental mixtures as powder precursors. The size of particles in the product of SHS reaction decreases with time of preliminary mechanical treatment ranging from 1 in untreated mixture to 0.1 in mixtures milled for 3 min. Subsequent mechanical treatment of the product of SHS reaction allowed the particles to be reduced down to 30-50 nm. Microstructural change of -Cu nanocomposite during spark plasma sintering (SPS) was also investigated. Under simultaneous action of pressure, temperature and electric current, titanium diboride nanoparticles distributed in copper matrix move, agglomerate and form a interpenetrating phase composite with a fine-grained skeleton.
        4,000원
        2.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The phenomenon of electrical explosion of conductors is considered in the context of the changes in the energy and structural states of the metal at the stages of energy delivery and relaxation of the primary products of EEC. It is shown that these changes are related to the forced interaction of an intense energy flux with matter and to the subsequent spontaneous relaxation processes. The characteristics of nano-sized metal powders are also discussed. The preferential gas media during EEC is Ar+. An increase in (in the range of values studied) leads to a reduction in the metal content. For reactive powders obtained with high metal content, it is necessary to separate the SFAP fractions, which settled on the negative electrode of the electric filter.
        4,000원
        4.
        2003.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Pure WC powders which does not include a binder phase were consolidated by spark plasma sintering (SPS) process at 1600~185 for 0~30 min under 50 MPa. Microstructure alid mechanical properties of binderless WC prepared by SPS were investigated. With increasing sintering temperature, sintered density and Vickers hardness of binderless WC increased. The fracture toughness of binderless WC was 7~15 MPa depending on the sintered density and decreased with increasing the Vickers hardness. It is found that the binderless WC prepared by SPS at 175 for 10 min under 50 MPa showed nearly full densification with fine-grained structure and revealed excellent mechanical properties of high hardness (~HV 2400) and considerably high fracture toughness (~7 MPa ).
        4,000원