Nanostructure control from amorphous composite system

Junichi Hojo, Masato Uehara, Naoya Enomoto

    Research output: Contribution to journalArticlepeer-review

    3 Citations (Scopus)

    Abstract

    Ceramic nanocomposites can be fabricated from composite powders. In particular, the nanostructure is easily formed from the finely-mixed amorphous state. The phase separation and crystallization of the composite powders during heating were investigated in Si3N4-BN and Si3N4-TiN systems. The powders were prepared by a vapor phase reaction method and heat-treated at 1600 °C in N2 with and without Y2O3-Al2O3 sintering aid. The crystallization and particle growth of Si3N4 were retarded by BN inclusion. Si3N4-BN composite powder was amorphous even at 1600 °C without sintering aid, whereas β-Si3N4 crystallized at 1600 °C with sintering aid. IR analysis indicated that Si3N4 and BN separated with a rise of temperature and the crystallization was accelerated by sintering aid. In Si3N4 TiN system, TiN accelerated the crystallization of β-Si3N4. It was found that BN was expelled from Si3N4 particles with and without sintering aid, whereas TiN was surrounded by Si3N4 particles with sintering aid. Si3N4-BN and Si3N4-TiN nanocomposites were fabricated by hot pressing at 1800 °C. The excellent thermal-shock resistance was observed in Si3N4-BN system and the high fracture toughness in Si3N4-TiN system in which the growth of Si3N4 rodlike grains was enhanced by fine TiN inclusions.

    Original languageEnglish
    Pages (from-to)975-980
    Number of pages6
    JournalFuntai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy
    Volume47
    Issue number9
    DOIs
    Publication statusPublished - Sep 2000

    All Science Journal Classification (ASJC) codes

    • Mechanical Engineering
    • Industrial and Manufacturing Engineering
    • Metals and Alloys
    • Materials Chemistry

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