Method for coating alumina containing refractory fibers with chromium oxide
AssigneeKennecott Corporation
InventorsRussell D. Smith, Richard E. Tressler
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Abstract
A method for uniformly coating ceramic fibers comprising from about 40 to 100 weight percent aluminum oxide with Cr.sub.2 O.sub.3. The method comprises precipitating Cr.sub.2 O.sub.3.xH.sub.2 O (chromium oxide hydrate) upon the fibers followed by converting the Cr.sub.2 O.sub.3.xH.sub.2 O to Cr.sub.2 O.sub.3. The resulting Cr.sub.2 O.sub.3 coated fibers have good shrinkage resistance, good temperature resistance and good flexibility in thick fiber articles.
Claims7
A method for uniformly coating ceramic fibers comprising from about 40 to 100 weight percent aluminum oxide, the fibers being contained in a mat having a thickness of at least 0.5 centimeters, with Cr.sub.2 O.sub.3 which method comprises precipitating Cr.sub.2 O.sub.3.xH.sub.2 O upon the fibers followed by converting the precipitated Cr.sub.2 O.sub.3.xH.sub.2 O to Cr.sub.2 O.sub.3.
A method for uniformly coating ceramic fibers of a fiber mat having a thickness of from 0.5 to 5.0 centimeters with Cr.sub.2 O.sub.3, said fibers of said mat comprising from about 40 to 100 weight percent aluminum oxide, which method comprises the following sequence of steps:
- (1) contacting the fibers of the mat with an aqueous solution containing from about 0.1 to about 7 weight percent of chromium ion;
- (2) while said fibers are in contact with said solution, raising the pH of the solution to above about 9.5 to precipitate Cr.sub.2 O.sub.3.xH.sub.2 O upon the fibers;
- (3) vaporizing the remaining water from the fibers;
- and
- (4) heating said fibers to from about 200.degree. to about 1200.degree. C. to convert said Cr.sub.2 O.sub.3.xH.sub.2 O to Cr.sub.2 O.sub.3.
Dependencies are inferred from the claim text.