Title: Pressureless sintering of silicon nitride ceramics with porous gradient structure for gas filter application

Authors: Fei Chen; Lingling Ma; Qiang Shen; Chuanbin Wang; Lianmeng Zhang

Addresses: Key Laboratory of Advanced Technology for Specially Functional Materials, Ministry of Education, Wuhan University of Technology, Wuhan 430070, China; State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China. ' State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China. ' State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China. ' State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China. ' Key Laboratory of Advanced Technology for Specially Functional Materials, Ministry of Education, Wuhan University of Technology, Wuhan 430070, China; State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China

Abstract: In the present study, Si₃N₄ ceramics with high porosity and porous gradient structure are prepared by pressureless sintering technique. Si₃N₄ ceramics with porosity of 34-47% are prepared by using ZrP₂O₇ as a binder material and heat treated at 1000°C in a nitrogen atmosphere. Si₃N₄ ceramics with porosity of 50-70% are prepared by using ZrP₂O₇ as a binder material, starch or naphthalene as a pore-forming agent and then heat treated at 1000°C in a nitrogen atmosphere. Si₃N₄ ceramics with porous gradient structure are then formed by laminating the Si₃N₄ porous ceramics with ordered porosity, followed by sintering at 1000°C. The phase compositions are analysed by X-ray diffraction (XRD), and the microstructure of the sintered samples is observed by scanning electronic microscope (SEM). The results show that the obtained Si₃N₄ ceramics exhibit a good porous-graded structure from high porosity to low porosity. The major phase of Si₃N₄ ceramics is still α phase.

Keywords: silicon nitride; porous gradient structure; pressureless sintering; pore forming agents; porous ceramics; gas filters; porosity.

DOI: 10.1504/IJMPT.2011.044909

International Journal of Materials and Product Technology, 2011 Vol.42 No.1/2, pp.3 - 11

Published online: 07 Mar 2015 *

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