Influence of processing route and SiO(2) on sintering ability, CTE, and dielectric constant of beta-Si(4)Al(2)O(2)N(6)
authors Ganesh, I; Thiyagarajan, N; Jana, DC; Sundararajan, G; Olhero, SM; Ferreira, JMF
nationality International
journal JOURNAL OF MATERIALS RESEARCH
keywords HYDROLYSIS-ASSISTED SOLIDIFICATION; BETA-SIALON CERAMICS; ALN POWDER; SUSPENSIONS; Y2O3
abstract Dense beta-Si(4)Al(2)O(2)N(6) and beta-Si(4)Al(2)O(2)N(6)-0.5SiO(2) ceramics were obtained from alpha-Si(3)N(4), alpha-Al(2)O(3), AlN, and Y(2)O(3) upon sintering green bodies consolidated by aqueous gel casting. For comparison purposes, a beta-Si(4)Al(2)O(2)N(6) was also prepared by the conventional dry-powder processing route. In the case of gel-cast beta-Si(4)Al(2)O(2)N(6), the as-purchased AlN powder was treated with H(3)PO(4) and Al(H(2)PO(4))(3) prior to use along with alpha-Si(3)N(4), alpha-Al(2)O(3), and Y(2)O(3). The gel-cast beta-Si(4)Al(2)O(2)N(6) exhibited superior hardness (1423 +/- 6 Hv), fracture toughness (3.95 +/- 0.3 MPa.m(1/2)), and coefficient of thermal expansion (CTE) (3.798 x 10(-6)/degrees C between 30 and 1000 degrees C) in comparison to the ceramic consolidated by conventional dry pressing, which exhibited only 1317 5 Hv, 3.30 +/- 0.2 MPa-m(1/2), and 3.532 x 10(-6)/degrees C between 30 and 700 degrees C. The in situ-generated similar to 9 wt% SiO(2) has considerably reduced the dielectric constant and CTE of beta-Si(4)Al(2)O(2)N(6) from 7.30 to 6.32 and from 3.798 x 10(-6)/degrees C to 3.519 x 10(-6)/degrees C respectively. The loss tangent property of the investigated materials was little influenced by the variation of chemical composition and processing route.
publisher CAMBRIDGE UNIV PRESS
issn 0884-2914
year published 2008
volume 23
issue 9
beginning page 2305
ending page 2311
digital object identifier (doi) 10.1557/JMR.2008.0302
web of science category Materials Science, Multidisciplinary
subject category Materials Science
unique article identifier WOS:000259515900003
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journal impact factor 2.502
5 year journal impact factor 2.251
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