Microstructure development and properties of novel Ba-doped phase Sialon ceramics

Basu, B. and Lewis, M.H. and Smith, M.E. and Bunyard, M. and Kemp, T. (2006) Microstructure development and properties of novel Ba-doped phase Sialon ceramics. Journal of the European Ceramic Society, 26 (16). pp. 3919-3924. ISSN 0955-2219

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Herein, we report the microstructure and properties of the newly developed near monophasic S-Sialon ceramic, based on the composition of Ba2Si12-xAlxO2+xN16-x (x = 20.2). Appropriate amount of the precursor powders (BaCO3, α-Si3N4, AlN, Al2O3) with a targeted composition of BaAlSi5O2N7 was ball milled and hot pressed to full density in the temperature range of 1600-1750 °C for 2 h in nitrogen atmosphere. Extensive transmission electron microscopy (TEM) study has been conducted to understand the microstructure development and characterise the various morphological features in hot pressed S-Sialon. The sintering mechanism is based on the liquid phase sintering route, which involves the formation of a Ba-Al silicate liquid (<5%) with dissolved nitrogen at intergranular pockets. The experimental observation suggests that the S-phase crystallises in elongated platelet morphology with preferred growth parallel to the orthorhombic 'c' axis and primary facet planes parallel to (1 0 0) and (0 1 0). The Ba-S-phase ceramic has an acoustically measured Young modulus of 210-230 GPa, a hardness of 13 GPa and a fracture toughness of 4 MPa m1/2, little lower than typical of a ceramic with morphologically anisotropic grains contributing to bridging and pullout mechanisms. © 2006 Elsevier Ltd. All rights reserved.

Item Type:
Journal Article
Journal or Publication Title:
Journal of the European Ceramic Society
Uncontrolled Keywords:
?? electron microscopymechanical propertiesmicrostructures-sialonsinteringanisotropybarium compoundscrystal growthcrystal microstructurecrystallizationelastic modulifracture toughnesshardnessmorphologytransmission electron microscopyfacet planesliquid phase ??
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04 Jan 2019 12:05
Last Modified:
15 Jul 2024 18:46