• Title/Summary/Keyword: 뮬라이트

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Densification Behaviors of Mullite with Addition of Feldspar Formed by Pressureless Powder Packing Forming Method (무가압분말충전성형법에 의해 제조된 뮬라이트 성형체의 장석 첨가량에 따른 치밀화 거동)

  • 박정현;황명의;강민수;조철구
    • Journal of the Korean Ceramic Society
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    • v.36 no.2
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    • pp.186-192
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    • 1999

  • Dang-Chin feldspar powder with the mean particle size of 9.1 $\mu\textrm{m}$ was added to the synthesized mullite powder with the particle size of +325∼-200 mesh and the powder compact was prepared by PLPP(pressureless powder packing method). Densification behaviors were observed in sintering temperature range of 1200∼1400$^{\circ}C$. The binder solution of 4% PVA was infilterated into packed powder to the suitable strength. The PLPP method makes it possible to form compacts without clay as plasticizer. Therfore there was no defect caused by phase transition after sintering. Additionally, we observed the dense microstructure by the melting of feldspar. When the mullite compacts with feldspar of 30% were sintered at 1300$^{\circ}C$-4 hrs, we obtained the dense microstructure with zero water absorption and porosity <1%. When these compacts were sintered longer than 4 hrs at 1300$^{\circ}C$ or higher than 1400$^{\circ}C$, the examggerated grain growth of mullite was observed.

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Cracks in Tape Cast Oxide Laminar Composites (테이프 캐스팅 산화물 층상 복합체에서의 균열)

  • Kim, Ji-Hyun;Yang, Tae-Young;Lee, Yoon-Bok;Yoon, Seog-Young;Park, Hong-Chae
    • Journal of the Korean Ceramic Society
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    • v.39 no.5
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    • pp.484-489
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    • 2002

  • Hot-pressure sintered laminar composites with alumina/zirconia or mullite/zirconia as an outer layer and alumina/zircon (resulting in reaction-bonded mullite/zirconia during sintering) as an inner layer were fabricated by tape casting and lamination. Various forms of crack were observed in sintered laminar composites, these cracks included channel cracks in the outer layer, transverse cracks in the inner layer and interface cracks debonding interlayer. Based on detailed microscopic observations, the cracks were attributed to thermal expansion mismatch between the oxides consisting of the each layer. In particular, the interlayer and transverse cracks were confirmed in the laminates consisted of the mullite/zirconia system as the outer layers, however, those cracks were not observed in the alumina/zirconia system used. In addition, the crack propagation did not exhibit same behavior in the two kinds of outer layer when the indentation load was applied.

  • https://doi.org/10.4191/KCERS.2002.39.5.484 인용 PDF KSCI

Effect of Al addition on Mullitization Behavior of Shell Mold during Sintering (Al 첨가에 따른 소성중 쉘 몰드의 뮬라이트화 거동)

  • Kim, Jae-Won;Kim, Du-Hyeon;Seo, Seong-Mun;Jo, Chang-Yong;Kim, Ju-Ryang;Choe, Seung-Ju
    • Korean Journal of Materials Research
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    • v.9 no.8
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    • pp.843-848
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    • 1999

  • The efect of A1 addition and sintering condition on mutization behavior between alumina and silica in alumina-based shell mold was investigated. A1 addition and high sintering temperature increased the degree of mullitization between alumina/silica but decreased the room temperature strentgh of the shell molds. It was identified that the sintered strength of the shell molds was in range of 2.0~2.6kg/$\textrm{mm}^2$. Al addition suppressed deflection of the shell molds at high temperature. Especially, no deflection was observed in the specimen which was sintered at $1000^{\circ}C$ for 1hr with 2.5wt% Al. The specimen sintered at $1500^{\circ}C$ for 4hrs with no Al addition also displayed no deflection.

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