著者

幾原 雄一 栗下 裕明 吉永 日出男

出版者

公益社団法人日本セラミックス協会

雑誌

窯業協會誌 (ISSN:18842127)

巻号頁・発行日

vol.95, no.1102, pp.638-645, 1987-06-01

被引用文献数

9 18

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In order to in vestigate the effect of grain boundary structure on the high-temperature strength of SiC, three kinds of SiC materials were prepared by pressureless sintering; material A with sintering aids of B+C, material B with B+C+AlN, and material C without any sintering aid. Their strength was measured by three-point bending at temperatures from room temperature to 2070K. The grain boundary structure was observed by HR-TEM. The following results were obtained.<br>(1) The strength of material A increases with increasing temperature up to 2070K. The fracture mode is transgranular at all temperatures studied. At the grain boundaries observed, a non-crystalline phase of 2-5nm in thickness is always found. This phase is thought to be either a compound of B and C or an extended grain boundary.<br>(2) The strength of material B increases up to 1770K, but above that temperature it decreases rapidly. The fracture mode also changes at that temperature from transgranular to intergranular. There exists also a 2-5nm thick non-crystalline phase at grain boundaries. The boundary phase is thought to be a compound in the system B-C-AlN. Above 1770K this phase is considered to flow viscously under stress to bring about boundary sliding which causes the strength to decrease.<br>(3) The strength of material C is almost independent of temperature. There exists again a 3-5nm thick non-crystalline phase at grain boundaries, but the boundary phase is thought to be an extended grain boundary.<br>(4) The dihedral angles observed in material C are frequently much larger than the critical angle of 60°. This observation is against the Prochazka's thermodynamic limitation, γ_gb/γ_sv<√3. The large dihedral angles may come from the existence of a grain boundary phase, which lowers the boundary energy.<br>(5) Densification of materials A and B is thought to proceed by the diffusion through the grain boundary phases.

著者

川合 將義 渡辺 精一 粉川 博之 川崎 亮 長谷川 晃 栗下 裕明 菊地 賢司 義家 敏正 神山 崇 原 信義 山村 力 二川 正敏 深堀 智生 斎藤 滋 前川 克廣 伊藤 高啓 後藤 琢也 佐藤 紘一 橋本 敏 寺澤 倫孝 渡辺 幸信 徐 超男 石野 栞 柴山 環樹 坂口 紀史 島川 聡司 直江 崇 岩瀬 宏 兼子 佳久 岸田 逸平 竹中 信幸 仲井 清眞

出版者

大学共同利用機関法人高エネルギー加速器研究機構

雑誌

基盤研究(S)

巻号頁・発行日

2007

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高エネルギー高強度陽子ビーム場の材料は、強烈な熱衝撃や放射線によって損傷を受ける。衝撃損傷過程と影響を実験的に調べ、その緩和法を導いた。また放射線損傷を理論的に評価するコードを開発した。さらに、損傷に強い材料として従来の材料に比べて強度の4倍高く室温で延性を持つタングステン材と耐食性が4倍高いステンレス鋼を開発した。衝撃実験における応力発光材を用いた定量的な方法を考案し、実用化の目処を得た。