Electronic Resource
s.l. ; Stafa-Zurich, Switzerland
Advances in science and technology
Vol. 45 (Oct. 2006), p. 1405-1410
ISSN:
1662-0356
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Natural Sciences in General
,
Technology
Notes:
The purpose of the study was to increase the thermal conductivity of multilayered andself-sealing ceramic matrix composites via the silicon melt infiltration process.The first step of the process consisted in filling porosity using various organic xerogels by thesol-gel route. Carbon xerogels obtained by subsequent pyrolysis may reduce and homogenize theporous network within the composite. Cracking of the xerogels due to volumic shrinkageoccurring during air drying may be decreased by controlling the initial parameters as concernsthe gel solution and/or by operating a second impregnation/pyrolysis step.Filling of such composites by liquid silicon revealed that a specific route and particularconditions are necessary to eliminate porosity by controlling gas production species from poresurface at high temperature. This may be achieved through a directional flow and using highlyviscous silicon (thanks to a localized wick), and by keeping the sides of the materials permeableto gas.This led to composite materials with a thermal conductivity which was four times as high as thatof those materials densified via CVI. An increase in mechanical properties was also observed
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/42/transtech_doi~10.4028%252Fwww.scientific.net%252FAST.45.1405.pdf
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