Compositions: ceramic – Ceramic compositions – Aluminum compound containing
Patent
1981-10-19
1982-11-02
McCarthy, Helen M.
Compositions: ceramic
Ceramic compositions
Aluminum compound containing
264332, 501152, C04B 3544
Patent
active
043574270
ABSTRACT:
Method for preparing finely divided high purity alumina doped with a small predetermined percentage of magnesia. In the preparation, there is first formed a mixed clear solution of aluminum alkoxide and a small amount of magnesium in the form of alkoxide or water soluble magnesium salt. There is then included with the clear solution a substantial excess of water over that required to completely hydrolyze the alkoxide and there is added thereto a small amount of selected acid which is effective to peptize the resulting slurry. The formed milky slurry is then allowed to become fully peptized to form a clear sol. The clear sol is converted to a finely divided and dried powder either by forming the sol into a gel, which is then dried, and mechanically reduced to a powder status or by spray drying the sol at elevated temperatures which produces the dried powder. Thereafter, the finely divided and dried powder is calcined at a temperature of from about 700.degree. C. to about 900.degree. C., with the crystalline structure of the powder predominately being that of a delta alumina. The preparation of this alumina is very economic and the resulting material is suitable for being isostatically pressed into a tubular form and then sintered to translucent tubular form to a density which closely approaches theoretical.
REFERENCES:
patent: 3026210 (1962-03-01), Coble
patent: 3941719 (1976-03-01), Yoldas
patent: 4150317 (1979-04-01), Laska
patent: 4266978 (1981-05-01), Prochazka
patent: 4318995 (1982-03-01), Rhodes et al.
Yoldas, B. E., "Alumina Sol Preparation from Alkoxides", Bull. Am. Cer. Soc. 54 (3) Mar. 1975, pp. 289-290.
Ho Shih-Ming
Mattox Douglas M.
Yoldas Bulent E.
McCarthy Helen M.
Palmer W. D.
Westinghouse Electric Corp.
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