Porous Si₃N₄ Fabricated Using Benzoic Acid as Pore-Forming Agent

Abstract:

In this study, porous Si₃N₄ ceramics with interconnected pores were prepared by cold isostatic pressing using benzoic acid as a pore-foring agent. The pore-forming agent of green bodies was sublimation rapidly below 200°C without carbon remained. Mechanical Properties were tested by universal testing machine, and the microstructures of the specimen were observed by scanning electron microscopy (FEI Sirion 200). The resulting shows, many fibrous β-Si₃N₄ grains grown from the internal wall of the round pores, and the porous distribution uniform in the matrix. By changing the content of benzoic acid, the silicon nitride ceramics with different porosity was fabricated. As the acid content decreased from 15wt% to zero, the porosities decreased from 57.6% to 48.0%, flexural strength increased from 36.8MPa to 141.2MPa. Both the grains and suitable interfacial bonding strength contributes to the high fracture strength.

• Periodical: Key Engineering Materials (Volumes 512-515)
• Pages: 820-823
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.512-515.820
• Online since: June 2012
• Authors: Hong Sheng Wang, Kai Liu, Chong Hai Wang, Jian Liu, Rong Liao, Fang Gao, Rui Xiang Liu
• Keywords: Benzoic Acid, Mechanical Property, Porosity, Porous Si₃N₄

References

[1] H. Mori, S. Mase, N. Yoshimura, et al, Fabrication of supported Si3N4 membranes using the pyrolysis of liquid polysilazane precursor, Journal of Membrane Science, 147(1998)23.

DOI: 10.1016/s0376-7388(98)00116-1

[2] F.L. Riley, Silicon nitride and related materials, Journal of the American Ceramic Society, 83(2000) 245.

[3] J. Yang, J.F. Yang, S.Y. Shan, et al, Effect of sintering additives on microstructure and mechanical properties of porous silicon nitride ceramics, Journal of the American Ceramic Society, 89 (2006) 3843.

DOI: 10.1111/j.1551-2916.2006.01294.x

[4] O.O. Omatcte, M.A Janncy, R.A. Strcklow, Gelcasting--a new ceramic forming process, Am Ceram Soc Bull, 70(1991)1641.

[5] T. Fukasawa, Z.Y. Deng, M. Ando, et al, Synthesis of silicon nitride with unidirectionally aligned channels using freeze-drying process, Journal of the American Ceramic Society, 85(2002) 2151.

DOI: 10.1111/j.1151-2916.2002.tb00426.x

[6] P. Hyoungjoon, K. Hyoun-Ee, Microstructural evolution and mechanical properties of Si3N4 with Yb2O3 as a sintering additive, Journal of the American Ceramic Society, 80(1997)750.