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1994 Fiscal Year Final Research Report Summary

Grain-boundary Cavitation and Creep Fracture of Ceramics

Research Project

Project/Area Number 05453078
Research Category

Grant-in-Aid for General Scientific Research (B)

Allocation TypeSingle-year Grants
Research Field Inorganic materials/Physical properties
Research InstitutionKyoto Institute of Technology

Principal Investigator

OKAMOTO Yasunori  Kyoto Institute of Technology, Dept.Chem.Mater.Tech., Associate Professor, 工芸学部, 助教授 (50101259)

Co-Investigator(Kenkyū-buntansha) HAYASHI Kunio  Kyoto Institute of Technology, Dept.Chem.Mater.Tech., Professor, 工芸学部, 教授 (30027817)
Project Period (FY) 1993 – 1994
KeywordsCeramics / Deformation / Creep / Fracture / Crack / Fatigue / Grain boundary / Strength
Research Abstract

The high-temperature mechanicalproperties of fine and dense ceramic materials were investigated. In fine grained mullites, which were fabricated using a fine grained sol-gel powder and have high resistance to creep deformation, static fatigue due to subcritical crack growth (SCG) at relatively higher stresses and creep fracture due to grain-boundary cavitation at lower stresses were observed at temperatures<greater than or equal>1200゚C.The similar transition of fracture mechanism with stress and temperature, which is important from the viewpoint of life assessment, should take place in other ceramics (alumina, magnesia, zirconia and their composites), therefore the experimental study is carried out in the process of the research. The creep deformation and creep fracture of fine grained alumina and zironia (Y-TZP), both with grain sizes<1mum, were studied. Y-TZP deforms superplastically, showing nonniform deformation with materials transport (diffusion) near the grain boundaries. The grain boundary in Y-TZP seems to be stable at high temperatures ; the grain growth during deformation, or dynamic grain growth, is limited. On the other hand, fine-grained alumina deforms by diffusional (Coble) creep at high strain rates, limited by interface reaction, followed by strain hardening due to dynamic grain growth, causing intergranular cavitation. Thus the grain boundary in alumina is relatively unstable in spite of small addition of magnesia. These results obtained in the research suggests that the grain boundary plays an important role in deformation and fracture at high temp

  • Research Products

    (14 results)

All Other

All Publications (14 results)

  • [Publications] Than Min Kyaw 他: "Mechanical Properties of Mullite-Zirconia Composites" Proceedings of 1993 Powder Metallurgy World Congress. 1333-1336 (1993)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Than Min Kyaw 他: "High Temperature Mechanical Properties of Mullite-Zirconia Composites" Advanced Materials-New Processes and Reliability (Proc.3rd Japan International SAMPE Sympo.). 1. 636-640 (1993)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 岡本泰則: "複合化の科学と技術VII.2.高温特性-変形と破壊-" セラミックス. 29. 515-522 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Shiono 他: "Preparation and Sinterability of Forsterite Powders Derived from Heterogeneous Alkoxide Solution Containing Fine Mgo Powders" J.Jpn.Soc.Powder and Powder Matall.41. 573-576 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Y.Okamoto 他: "Deformation Mechanisms of Fine-grained Alumina and Y-TZP" Trans Mater,Res.Soc.Jpn.(Aduanced Materials′93,II). 16B. 925-928 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 岡本泰則: "高温材料としてのセラミックス-変形と破壊-" 化学工業. 46. 53-60 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] G.Pezzotti 他: "Phenomendogy of Fracture and Fracture Mechanisms under Slow-crack growth/Ceep Regimes in High-purity Si_3N_4 and its SiC-platelet Composites" Acta Metall.Mater.(印刷中).

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.M.Kyaw, et al.: "Mechanical Properties of Mullite-Zirconia Composites" Proceedings of 1993 Powder Metallurgy World Congress. 1333-1336 (1993)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T.M.Kyaw, et al.: "High Temperature Mechanical Properties of Mullite-Zirconia Composites" Advanced Materials-New Processes and Reliability- (Proc.3rd Jpn International SAMPE Symposium). Vol.1. 636-640 (1993)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Y.Okamoto: "Science and Technology in Composite Materials VII.2. High-temperature Mechanical Properties-Deformation andFracture-" Geramics Japan (Bull.Ceram.Soc.Jpn). 29. 515-522 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T.Shiono, et al.: "Preparation and sinterability of Forsterite Powders Derived from Heterogeneous Alkoxide Solution Containing Fine MgO Powders" J.Jpn.Soc.Powder and Powder Metall.41. 573-576 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Y.Okamoto, et al.: "Deformation Mechanisms of Fine-grained Alumina and Y-TZP" Trans.Mat.Res.Soc.Jpn.16B (Advanced Materials '93, IIIB). 925-928 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Y.Okamoto: "Ceramics as High-temperature Materials-Deformation and Fracture-" Chemical Industry. 46. 53-60 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] G.Pezzotti, et al.: "Phenomenology of Fracture and Fracture Mechanisms under Slow-crack-growth/Creep Regimes in High-purity Si_3N_4 and its SiC-platelet Composite" Acta Metall.Mater. (in print).

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1996-04-15  

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