粉体および粉末冶金
Online ISSN : 1880-9014
Print ISSN : 0532-8799
ISSN-L : 0532-8799
59 巻, 1 号
January
選択された号の論文の11件中1~11を表示しています
研究
研究
  • 渥美 太郎, 武 成祥, 松沼 宏佳, 熊倉 俊寿
    2012 年 59 巻 1 号 p. 3-7
    発行日: 2012年
    公開日: 2012/02/08
    ジャーナル オープンアクセス
    Fine sand generated in a recycling process of waste foundry sand is used as raw material for cement. In order to find more effective use for the fine sand, we attempted to synthesize mullite using the sand as a silica source. Self-propagating high-temperature synthesis was carried out by adding thermite powder, a mixture of aluminum and iron oxide (III) with a molar ratio of 2:1, to the fine sand. A mixture containing 20 wt% of fine sand was heated to a maximum temperature of approximately 1660 K by an exothermic reaction, and the major products of this reaction were mullite and iron. The maximum combustion temperature of a mixture with more than 20 wt% of fine sand decreased with an increase in the fine sand content. In these cases, not all of the fine sand reacted: the reaction products were corundum, hematite, mullite and iron.
  • 大浦 勇士, 町田 信也, 木下 俊二, 内藤 宗幸, 重松 利彦, 近藤 繁雄
    2012 年 59 巻 1 号 p. 8-13
    発行日: 2012年
    公開日: 2012/02/08
    ジャーナル オープンアクセス
    A cold-pressed pellet of ion-conducting glassy powders generally shows lower conductivity than a monolithic bulk glass with the same chemical composition. This degradation of ion conductivity of the cold-pressed pellet would be caused by interfacial resistances between glassy particles. In order to improve the conductivity of glassy pellet, we tried a hot-press method for the glassy powder in the chemical composition 75Li2S·5P2S3·20P2S5 (mol%) at around its glass-transition temperature. The hot-pressed pellet under the conditions: pressure 200 MPa, heating temperature 483 K, heating rate 5 Kmin-1 and heating time 1 h, showed high ion conductivity at 298 K, σ298K=1.5×10-3 Scm-1, and the activation energy Ea= 33 kJmol-1. Those ion conducting properties of the hot-pressed pellet were superior to those of a pellet cold-pressed at 200 MPa (σ298K= 6.1×10-4 Scm-1, Ea= 38 kJmol-1).
特集:高機能電子部品材料プロセス技術の新しい展開
総報
研究速報
  • 山下 恭平, 小郷 義久, 寺西 貴志, 林 秀考, 岸本 昭
    2012 年 59 巻 1 号 p. 17-21
    発行日: 2012年
    公開日: 2012/02/08
    ジャーナル オープンアクセス
    The effect of reducing atmosphere on yttria dispersed AlN ceramics sintered by millimeter wave-HIP combined sintering was investigated. The specimens were sintered by millimeter wave (MMW) heating under nitrogen reducing atmosphere containing 3 vol% hydrogen followed by post-HIP treatment at 1700°C for 0.5 h under nitrogen pressure of 190 MPa. The relative densities to the theoretical one saturated at the first MMW heating over 1700°C. Thermal conductivities of AlN ceramics sintered by MMW heating under heavily reduced atmosphere with nitrogen were higher than that through MMW heating under normally reduced atmosphere. The thermal conductivity increased with decreasing the yttria additive amount and with increasing the sintering temperature. The optimized yttria dispersion amount was 1 wt% in the MMW heating at 1800°C for 0.5 h. Relative density and thermal conductivity increased by post-HIP treatment. The optimized yttria dispersion amount shifted from 1 wt% to 3 wt% after post-HIP treatment.
解説
研究
  • 佐々木 大地, 世利 修美
    2012 年 59 巻 1 号 p. 29-33
    発行日: 2012年
    公開日: 2012/02/08
    ジャーナル オープンアクセス
    Electrochemical attempts have been made to obtain fine powders of MgAl2O4 spinel by applying metallic corrosion in ethanol with addition of chloride ions as catalyst. The obtained corrosion product, which contains mixture of metallic ions and ethoxides, was hydrolyzed and fired. The sintered powders of MgAl2O4 were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The MgAl2O4 spinel powders of 30∼100 nanometer size particle aggregation were obtained by firing above 1273 K. A new spinel synthesis method which was easy and low cost was proposed and considered in the electrochemical point of view, and its merits and demerits for production were enumerated.
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