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

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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.

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Periodical:

Key Engineering Materials (Volumes 353-358)

Edited by:

Yu Zhou, Shan-Tung Tu and Xishan Xie

Pages:

1525-1528

Citation:

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

Online since:

September 2007

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$38.00

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