- Design of Nanocluster Based Material with Catalytic Properties
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Nakayama Tadachika, Chang-Yeoul Kim, Sekino Tohru, Yong-Ho Choa, Kusunose Takafumi, Hayashi Yamato, Niibara Koichi
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J Korean Powder Metall Inst. 2001;8(3):197-200.
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- Modified inert gas condensation method was used to produce the nanocluster composites of CuO/CeO_2. High-resolution TEM, SEM and catalytic measurements have been used to characterize the samples and study the synergistic effect between the CuO phase and CeO_2(ceria) support. By varying the He pressure, the heating temperature and configuration of the heating boats inside the modified gas condensation chamber, nanoclusters of varying sizes, shapes and composition can be produced. The composition and nanostructured morphology were shown to influence the catalytic properties of the system. A copper content around 10 at% with a morphology that favors high-energy surfaces of ceria is shown to be beneficial for a high catalytic activity.
- Processing of Nano-Sized Metal Alloy Dispersed Al_2O_3 Nanocomposites
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Sung-Tag Oh, Namkung Seok, Jai-Sung Lee, Hyoung-Seop Kim, Sekino Tohru
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J Korean Powder Metall Inst. 2001;8(3):157-162.
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Abstract
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- An optimum route to fabricate the ferrous alloy dispersed Al_2O_3 nanocomposites such as Al_2O_3/Fe-Ni and Al_2O_3/Fe-Co with sound microstructure and desired properties was investigated. The composites were fabricated by the sintering of powder mixtures of Al_2O_3 and nano-sized ferrous alloy, in which the alloy was prepared by solution-chemistry routes using metal nitrates powders and a subsequent hydorgen reduction process. Microstructural observation of reduced powder mixture revealed that the Fe-Ni or Fe-Co alloy particles of about 20 nm in size homogeneously surrounded Al_2O_3, forming nanocomposite powder. The sintered Al_2O_3/Fe-Ni composite showed the formation of FeAl_2O_4 phase, while the reaction phases were not observed in Al_2O_3/Fe-Co composite. Hot-pressed Al_2O_3/Fe-Ni composite showed improved mechanical properties and magnetic response. The properties are discussed in terms of microstructural characteristics such as the distribution and size of alloy particles.
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