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        검색결과 2

        1.
        2006.09 구독 인증기관·개인회원 무료
        Several boride sintered bodies such as , , and were previously reported. In the present study, the sinterability and physical properties of chromium boride containing chromium carbide sintered bodies were investigated in order to determine its new advanced material. The samples were sintered at desired temperature for 1 hour in vacuum under a pressure by hot pressing. The relative density of sintered bodies was measured by Archimedes' method. The relative densities of addition of 0, 5, 10, 15 and 20 mass% composites were 92 to 95%. The Vickers hardness of the with 10 and 15 mass% composites were about 14 and 15 GPa at room temperature, respectively. The Vickers hardness at high temperature of the addition of 10 mass% composite decreased with increasing measurement temperature. The Vickers hardness at 1273 K of the sample was 6 GPa. The Vickers hardness of addition of composites was higher than monolithic sintered body. The powder X-ray diffraction analysis detected CrB and phases in containing composites.
        2.
        2006.09 구독 인증기관·개인회원 무료
        Mechanochemical synthesis of zinc ferrite, ZnFe2O4, was attempted from a powder mixture of iron (III) oxide, alpha-Fe2O3 and zinc (II) oxide, ZnO. Nanocrystalline zinc ferrite, ZnFe2O4 powders were successfully synthesized only bymilling for 30 hours. Evidence of the ZnFe2O4 formation was absent for the powders milled for 10 and 20 hours; the milling lowered the crystallinity of the starting materials. Heating after milling enhanced the formation of ZnFe2O4, crystal growth of ZnFe2O4 and the unreacted starting materials. The unreacted starting materials decreased their amounts by heating at higher temperatures.