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Al2O3–SiC composites prepared by warm pressing and sintering of an organosilicon polymer-coated alumina powder

Galusek, Dušan ; Sedláček, Jaroslav ; Riedel, Ralf (2007):
Al2O3–SiC composites prepared by warm pressing and sintering of an organosilicon polymer-coated alumina powder.
In: Journal of the European Ceramic Society, 27 (6), pp. 2385-2392. SciVerse, ISSN 09552219,
[Article]

Abstract

Al2O3/SiC micro/nano composites were prepared by axial pressing of poly(allyl)carbosilane-coated submicrometre alumina powder at elevated temperature (called also warm pressing, or plastic forming) with subsequent pressureless sintering in the temperature interval between 1700 and 1850 °C. Warm pressing at 350 °C and 50 MPa resulted in green bodies with high mechanical strength and with markedly higher density than in green bodies prepared by cold isostatic pressing of the same powder at 1000 MPa. The sintering of warm pressed specimens moreover yielded the composites with higher final density (less than 4% of residual porosity) with the microstructure composed of micrometer-sized alumina grains (D50 < 2 μm) with inter- and intragranular SiC precipitates. High sintering temperatures (>1800 °C) promoted the formation of intergranular platelets identified by TEM as 6H polytype of α-SiC. The maximum hardness (19.4 ± 0.5 GPa) and fracture toughness (4.8 ± 0.1 MPa m1/2) were achieved in the composites containing 8 vol.% of SiC, and sintered for 3 h at 1850 °C. These values are within the limits reported for nanocomposites Al2O3/SiC by other authors and do not represent any significant improvement in comparison to monolithic alumina.

Item Type: Article
Erschienen: 2007
Creators: Galusek, Dušan ; Sedláček, Jaroslav ; Riedel, Ralf
Title: Al2O3–SiC composites prepared by warm pressing and sintering of an organosilicon polymer-coated alumina powder
Language: English
Abstract:

Al2O3/SiC micro/nano composites were prepared by axial pressing of poly(allyl)carbosilane-coated submicrometre alumina powder at elevated temperature (called also warm pressing, or plastic forming) with subsequent pressureless sintering in the temperature interval between 1700 and 1850 °C. Warm pressing at 350 °C and 50 MPa resulted in green bodies with high mechanical strength and with markedly higher density than in green bodies prepared by cold isostatic pressing of the same powder at 1000 MPa. The sintering of warm pressed specimens moreover yielded the composites with higher final density (less than 4% of residual porosity) with the microstructure composed of micrometer-sized alumina grains (D50 < 2 μm) with inter- and intragranular SiC precipitates. High sintering temperatures (>1800 °C) promoted the formation of intergranular platelets identified by TEM as 6H polytype of α-SiC. The maximum hardness (19.4 ± 0.5 GPa) and fracture toughness (4.8 ± 0.1 MPa m1/2) were achieved in the composites containing 8 vol.% of SiC, and sintered for 3 h at 1850 °C. These values are within the limits reported for nanocomposites Al2O3/SiC by other authors and do not represent any significant improvement in comparison to monolithic alumina.

Journal or Publication Title: Journal of the European Ceramic Society
Journal volume: 27
Number: 6
Publisher: SciVerse
Uncontrolled Keywords: Al2O3, SiC; Al2O3/SiC, Precursors-organic, Mechanical properties
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Dispersive Solids
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 17 Apr 2012 09:27
Official URL: http://dx.doi.org/10.1016/j.jeurceramsoc.2006.09.007
Identification Number: doi:10.1016/j.jeurceramsoc.2006.09.007
Funders: The financial support of this work by the Alexander von Humboldt Foundation, Bonn, Germany, and by the Slovak National Grant Agency VEGA, under the contract number 2/6181/26, is gratefully acknowledged.
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