Title: Fabrication of Si₃N₄-based seal coating on porous Si₃N₄ ceramics

Authors: Qiang Shen; Ying Yang; Fei Chen; Lianmeng Zhang

Addresses: 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; Key Laboratory of Advanced Technology for Specially Functional Materials, Ministry of Education, Wuhan University of Technology, Wuhan 430070, China

Abstract: In this study, Si₃N₄-based seal coatings using MgO, Al₂O₃ and SiO₂ as the sintering additives were prepared on the porous Si₃N₄ substrates by room temperature spraying and pressureless sintering. The composition of the Si₃N₄-based seal coatings was well designed, in order to both match the coefficient of thermal expansion with that of the porous Si₃N₄ substrate and form the liquid phase at a relative low temperature. During the sintering process, the liquid phases promote the densification and homogenisation of the Si₃N₄-based seal coatings. A good combination between Si₃N₄-based seal coatings and substrate is achieved, as a result of the liquid-phase penetration into the pores in the porous Si₃N₄ substrate.

Keywords: silicon nitride; seal coatings; spraying; pressureless sintering; porous ceramics.

DOI: 10.1504/IJMPT.2011.044910

International Journal of Materials and Product Technology, 2011 Vol.42 No.1/2, pp.12 - 20

Published online: 07 Mar 2015 *

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