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Microstructure and Properties of Porous Si 3 N 4 Ceramics with a Dense Surface
Author(s) -
Li Xiangming,
Yin Xiaowei,
Zhang Litong,
Pan Tianhao
Publication year - 2011
Publication title -
international journal of applied ceramic technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 57
eISSN - 1744-7402
pISSN - 1546-542X
DOI - 10.1111/j.1744-7402.2009.02472.x
Subject(s) - materials science , microstructure , ceramic , composite material , porosity , sintering , chemical vapor deposition , fracture toughness , flexural strength , dielectric , deposition (geology) , nanotechnology , paleontology , optoelectronics , sediment , biology
Porous Si 3 N 4 ceramics with a dense surface are fabricated by a joint process of pressureless sintering and chemical vapor deposition (CVD). Before CVD, the Si 3 N 4 ceramic shows a uniform microstructure with well‐distributed pores. During CVD, the depositions of Si 3 N 4 in the inner surface and on the external surface of the ceramics lead to a decrease of porosities and pore sizes. As a result, both the flexural strength and fracture toughness of the Si 3 N 4 ceramic increase by >30%, the surface hardness increases more than five times, and the dielectric constant and loss increase slightly.