Porous SiC_nw/SiC ceramics with unidirectionally aligned channels produced by freeze-drying and chemical vapor infiltration

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• 作者：Daoyang Han ; Hui Mei ; ^{phdhuimei@yahoo.com" class="auth_mail" title="E-mail the corresponding author} ; ^{419612788@qq.com" class="auth_mail" title="E-mail the corresponding author} ; Shanshan Xiao ; Junchao Xia ; Jinlei Gu ; Laifei Cheng
• 关键词：Unidirectional freeze-drying ; Silicon carbide nanowire (SiCnw) aerogel ; Chemical vapor infiltration (CVI) ; Porous silicon carbide nanowire/silicon carbide (SiCnw/SiC) ceramics
• 刊名：Journal of the European Ceramic Society
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：37
• 期：3
• 页码：915-921
• 全文大小：4139 K

文摘

The current study introduces a methodology for the fabrication of porous silicon carbide nanowire/silicon carbide (SiC_nw/SiC) ceramics with macroscopic unidirectionally aligned channels and reports on their microstructural and mechanical properties. The material was produced by freezing of a water-based slurry of β-SiC nanowires (SiC_nw) with control of the ice growth direction. Pores were subsequently generated by sublimation of the columnar ice during freeze-drying. Chemical vapor infiltration (CVI) of SiC into the open pore network of the SiC_nw aerogel with unidirectionally aligned channels, resulted in the formation of highly porous SiC_nw/SiC ceramics which exhibited a unique microstructure as identified by scanning electron microscopy. The pore size distribution and the mechanical properties of the as-fabricated porous ceramics were examined by mercury intrusion porosimetry and three-point bending and compression tests, respectively, while phase composition was investigated through X-ray diffraction.