Strengthening Effect of In-Situ Dispersed Hexagonal Boron Nitride in Ceramic Composites

Abstract:

Article Preview

High strength particulate ceramic composites are in general reinforced by strong dispersoids, such as strong ceramic particles (SiC, TiB2, ZrO2, et al) and strong metallic particles (Mo, W, et al). In this work high strength ceramic composites with in-situ synthesized hexagonal boron nitride (h-BN) have been prepared and characterized. As an example, we manufactured mullite-BN composites by reactive hot pressing (RHP) using aluminum borates (9Al2O3·2B2O3 and 2Al2O3·B2O3) and silicon nitride as starting materials. The obtained material RHPed at 1800°C showed a strength of 540 MPa, which was 1.64 times higher than that of the monolithic mullite ceramics. TEM observation revealed that the composite had an isotropic microstructure with a fine mullite matrix grain size of less than 1 μm and a nano-sized h-BN platelets of about 200 nm in length and 60∼80 nm in thickness. The high strength was suggested to be from the reduced matrix grain size and the small toughening effect by the h-BN platelets. In addition, this kind of ceramic composite demonstrates low Young’s modulus that is beneficial to the thermal/mechanical shock resistance, and excellent machinability.

Info:

Periodical:

Key Engineering Materials (Volumes 317-318)

Edited by:

T. Ohji, T. Sekino and K. Niihara

Pages:

163-166

DOI:

10.4028/www.scientific.net/KEM.317-318.163

Citation:

G. J. Zhang et al., "Strengthening Effect of In-Situ Dispersed Hexagonal Boron Nitride in Ceramic Composites", Key Engineering Materials, Vols. 317-318, pp. 163-166, 2006

Online since:

August 2006

Export:

Price:

$35.00

[1] G. J. Zhang, Y. Beppu, T. Ohji and S. Kanzaki: Acta Mater. Vol. 49 (2001), p.77.

[2] G. J. Zhang, J. F. Yang, M. Ando, T. Ohji and S. Kanzaki: Acta Mater. Vol. 52 (2004), p.1823.

[3] G. J. Zhang, J. F. Yang, T. Ohji and S. Kanzaki: Adv. Eng. Mater. Vol. 4 (2002), p.15.

[4] G. J. Zhang, J. F. Yang, M. Ando, T. Ohji and S. Kanzaki: Adv. Eng. Mater. Vol. 5 (2003), p.741.

[5] G. J. Zhang and T. Ohji: J. Am. Ceram. Soc. Vol. 84 (2001), p.1475.

[6] G. J. Zhang and T. Ohji: J. Mater. Res. Vol. 15 (2000), p.1876.

[7] G. J. Zhang, J. F. Yang, Z. Y. Deng and T. Ohji: J. Ceram. Soc. Japan Vol. 109 (2001), p.45.

[8] G. J. Zhang, J. F. Yang, M. Ando and T. Ohji: J. Am. Ceram. Soc. Vol. 85 (2002), p.2938.

[9] G. J. Zhang, J. F. Yang, M. Ando, T. Ohji and S. Kanzaki: J. Am. Ceram. Soc. Vol. 87 (2004), p.296.

[10] G. J. Zhang, J. F. Yang and T. Ohji: Mater. Sci. Eng. A Vol. A328 (2002), p.201. Figure 2. Schematic microstructure feature of the obtained in situ mullite-BN composite.

In order to see related information, you need to Login.