Microstructure of boron carbide pressureless sintered in an Ar atmosphere containing gaseous metal species

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• 作者：Hiroyuki Miyazaki ; You Zhou ; Hideki Hyuga ; Yu-ichi Yoshizawa ; Takeshi Kumazawa
• 关键词：Sintering ; Microstructure-final ; Carbide ; Boron carbide
• 刊名：Journal of the European Ceramic Society
• 出版年：2010
• 出版时间：March 2010
• 年：2010
• 卷：30
• 期：4
• 页码：999-1005
• 全文大小：935 K

文摘

97.4 % of theoretical density was obtained for boron carbide (B₄C) ceramics by heating up to 2226 °C in an Ar atmosphere containing gaseous Al and Si species without external pressure. Impurities and secondary phases in the sintered B₄C samples were examined by X-ray fluorescence and X-ray diffraction analyses respectively, which revealed that both Al and Si elements infiltrated into the green compacts and reacted with B₄C to form SiC, Al₄C₃ and Al₄SiC₄ during the sintering. Triple junctions observed in the polished surfaces of the densified samples were filled by the secondary phases, indicating formation of liquid phase during heating. Dilatometric measurements at a constant heating rate in the Ar gas with the metallic gas species demonstrated that the shrinkage started at around 1700 °C, which was the liquid-phase formation temperature for the system reported in the previous studies. It was supposed that the liquid phase might be responsible for the densification.