アルミナのホットプレス中に起こる異状な結晶成長とオリエンテーション

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タイトル別名
  • Enhanced Grain Growth and Orientation in Hot-pressed Alumina
  • アルミナ ノ ホットプレス チュウ ニ オコル イジョウ ナ ケッショウ セイチョウ ト オリエンテーション

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抄録

Hot-pressing of alumina was caried out at 1700°-1900°C and 200-250kg/cm2 for 5-60 min in graphite molds heated by high-frequency induction. Three types of structures were microscopically observed in hot-pressed specimens, depending on hot-pressing conditions. Temperature increase under constant high pressures from low to high temperatures tended to give the layered-typed bodies consisting of the structures varied near outer surfaces and in central parts. Application of pressure subsequent to temperature increase gave comparatively homogeneous structures in hot-pressed alumina, in which noticeable orientation was observed under microscope and by X-ray diffraction method. In the oriented-typed specimens, the c-axes of alumina crystallites tended to be parallel to the hot-pressing direction. The orientation degree was determined by X-ray diffraction method in comparison with a standard specimen with an at-random structure. In the cases where temperature was increased by about 50°C during hot-pressing under the conditions which should give the above-described homogeneous oriented-typed structures, enhanced grain growth tended to be caused in alumina specimens which contained 0.6% Na2O, while the alumina with 0.08% Na2O showed no enhanced grain growth. The lengths of grain growth were often observed to be about 1mm. The bending strengths of grown-typed specimens were about one forth of those of oriented-typed ones.

収録刊行物

  • 窯業協會誌

    窯業協會誌 70 (798), 165-171, 1962

    公益社団法人 日本セラミックス協会

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