Effects of Various Rare Earth Sesquioxide Additives on Grain Growth in Millimeter-Wave Sintered Silicon Nitride Ceramics(Millimeter-Wave Heating)(<Special Issue>Recent Trends on Microwave and Millimeter Wave Application Technology)

  • HIROTA Masayuki
    College of Industrial Technology
  • VALECILLOS Maria-Cecilia
    Synergy Material Research Center, National Institute of Advanced Industrial Science and Technology (AIST)
  • BRITO Manuel E.
    Energy Electronics Institute, National Institute of Advanced Industrial Science and Technology (AIST)
  • HIRAO Kiyoshi
    Synergy Material Research Center, National Institute of Advanced Industrial Science and Technology (AIST)
  • TORIYAMA Motohiro
    Institute for Structural and Engineering Materials, National Institute of Advanced Industrial Science and Technology (AIST)

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Description

Using various rare earth sesquioxides as additives, silicon nitride (Si_3N_4) samples were sintered at 1700℃ for 4 h by millimeter-wave heating performed in an applicator fed by a 28GHz Gyrotron source under a nitrogen pressure of 0.1 Mpa. A comparative study of densification, grain growth behavior and mechanical properties of silicon nitride fabricated by millimeter-wave and conventional sintering was carried out. Bulk densities were measured by Archimedes' technique. Except for the Eu_2O_3 containing sample, all samples were densified to relative densities of above 97.0%. Microstructure of the specimens was analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). To investigate quantitatively the effect of millimeter-wave heating on grain growth, image analysis was carried out for grains in the specimens. Fracture toughness was determined by the indentation-fracture method (IF method) in accordance with Japan Industrial Standards (JIS). Fully dense millimeter-wave sintered silicon nitride presenting a bimodal microstructure exhibited higher values of fracture toughness than materials processed by conventional heating techniques. Results indicate that millimeter-wave sintering is more effective in en hancing the grain growth and in producing the bimodal microstructure than conventional heating. It was also confirmed that localized runaway in temperature, depending upon the sintering additives, can occur under millimeter-wave heating.

Journal

  • IEICE transactions on electronics

    IEICE transactions on electronics 86 (12), 2462-2468, 2003-12-01

    The Institute of Electronics, Information and Communication Engineers

Keywords

Details 詳細情報について

  • CRID
    1570009752558373760
  • NII Article ID
    110003214567
  • NII Book ID
    AA10826283
  • ISSN
    09168524
  • Text Lang
    en
  • Data Source
    • CiNii Articles

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