In Situ Toughened α-Sialon Ceramics Doped with Lutecia and Ytterbia



Ytterbia and Lutecia were adopted to stabilize α-sialon ceramics during a two-step hot press sintering, respectively. Although Yb3+ and Lu3+ possess the similar small ion size (0.86 Å and 0.85 Å) as two adjacent rare-earth elements, Yb- and Lu-α-sialon ceramics present very different microstructure and properties. Yb-α-sialon ceramic is fully composed of α-sialon phase without any secondary phase. The ceramic incorporated with Lu2O3 also consists of α-sialon phase, but a trace amount of intergranular phase J′ (Lu4Si2-xAlxO7+xN2-x) still remains at the boundary. Microstructure observation indicates the fully equiaxial grain morphology of Yb-α-sialon ceramic. However, elongated grains appear in the Lu-α-sialon ceramic, coexisting with small equiaxed grains. Owing to the almost full α-sialon phase assemblage, both ceramics present high hardness with the value of over 21 GPa. Lu-α-sialon ceramic possesses good toughness, which is attributed to the elongated grains assisting the facilitation of toughening mechanism. The equiaxied grain morphology results in a comparatively lower toughness for Yb-α-sialon ceramic.




Yu Zhou, Shan-Tung Tu and Xishan Xie




C. F. Liu et al., "In Situ Toughened α-Sialon Ceramics Doped with Lutecia and Ytterbia", Key Engineering Materials, Vols. 353-358, pp. 1525-1528, 2007


September 2007




[1] G.Z. Gao and R. Metselaar: Chem. Mater. Vol. 3 (1991), p.242.

[2] I. -W. Chen and A. Rosenflazn: Nature Vol. 389 (1997), p.701.

[3] Z.J. Shen, H. Peng and M. Nygren: J. Mater. Res. Vol. 17 (2002), p.336.

[4] R. Shuba and I. -W. Chen: J. Am. ceram. Soc. Vol. 85(5)(2002), p.1260.

[5] F. Ye, M.J. Hoffmann, S. Holzer, Y. Zhou and M. Iwasa: J. Am. ceram. Soc. Vol. 86(12)(2003), p.2136.

[6] C. Zhang, K. Komeya, J. Tatami and T. Meguro: J. Euro. Ceram. Soc. Vol. 20 (2000), p.939.

[7] A. Rosenflanz and I-W. Chen: J. Euro. Ceram. Soc. Vol. 19 (1999), p.2325.

[8] N. Camuscu, D.P. Thompson and H. Mandel: J. Euro. Ceram. Soc. Vol. 17 (1997), p.599.

[9] Z. Shen, T. Ekström and M. Nygren: J. Am. ceram. Soc. Vol. 79 (1996), p.721.

[10] Z.K. Huang and I. -W. Chen: J. Am. ceram. Soc. Vol. 79(8) (1996), p. (2091).

[11] N. Hiroski, Y. Yamamoto, T. Nishimura and M. Mitomo: J. Am. ceram. Soc. Vol. 85(11)(2002), p.2861.