Compositions: ceramic – Ceramic compositions – Refractory
Patent
1987-11-06
1990-01-09
Bell, Mark L.
Compositions: ceramic
Ceramic compositions
Refractory
501134, C04B 3510, C04B 3546
Patent
active
048928500
ABSTRACT:
A sintered body formed of corundum-alumina and rutile-titania which is prepared by adding an alkali metal to an alumina-titania composite powder produced by a vapor-phase reaction of AlCl.sub.3 and TiCl.sub.4, in the course of the oxidation reaction or by some treatment of the powder after the reaction; and sintering the powder at a temperature not lower than a minimum temperature at which a liquid phase is produced by a small amount of alkali metal oxide and titania and not higher than 1280.degree. C. has the characteristics which have never been obtained before.
The sintered body of the present invention comprises alumina of corundum phase and titania of rutile phase, which contains alkali metal in an amount of 0.01 to 0.5 wt % and plate-shaped corundum particles whose cross sections having aspect ratios of 2.5 or more are observed to be 10 vol % or more by scanning electron micrography. This sintered body can have a high toughness by the compounding inexpensive oxides such as alumina and titania.
The toughening mechanism of the present sintered body is due to a crack deflection effect by geometrically anisotropic particles which are dispersed in the material, and therefore the toughness is not expected to be deteriorated at high temperatures.
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Ruf et al, "Toughening by Monoclinic Zirconia", Journal of the American Ceramic Society, vol. 66, No. 5, pp. 328-332, May 1983.
Okamura et al, "Preparation and Sintering of Monosized Al.sub.2 O.sub.3 --TiO.sub.2 Composite Powder", Journal of the American Ceramic Society, vol. 69, No. 2, pp. C-22-C-24, Feb. 1986.
Bell Mark L.
Green Anthony J.
Kureha Chemical Industry Co. Ltd.
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