Appeal 2007-0687
Application 10/797,422
1 A thermally resistant barrier layer is applied to the surface of the
2 component to prevent contact of the fuel with catalytic agents such as iron,
3 nickel, and chromium contained in the base metals from which fuel
4 contacting components are fashioned. Specifically, the fuel contacting
5 components are coated with a thin, high temperature resistant layer of
6 alumina and silica, applied in specific ratios, from a specially formulated
7 sol-gel. Spence, col. 3, ll. 12-22.
8 Spence discloses that while the specification speaks in terms of
9 preparing sols of alumina and silica, it is intended that this terminology
10 encompass those known sols of mixtures of metals and compounds of metals
11 which will yield metal oxide mixtures upon deposition and subsequent
12 heating. Spence, col. 4, ll. 22-26.
13 Spence discloses that the alumina sol component of the mixed sol may
14 be prepared by the hydrolysis and peptization of the corresponding organo-
15 metallic compounds in an aqueous medium. Preferred organo-metallic
16 compounds include aluminum alkoxides. Spence, col. 5, ll. 11-17.
17 Spence discloses that deposition of the sol may be accomplished by
18 infiltration, spray, brush application, dipping, or immersion-evaporation
19 techniques. Spence, col. 10, ll. 42-44.
20 The method disclosed in Spence may be used to provide protective
21 coatings to a wide variety of substrates. Spence, col. 3, ll. 26-29.
22 Substrates include various ceramics. Spence, col. 4, ll. 40-42.
23 Ceramics and Glasses discloses that alumina is produced by heating
24 hydrates of alumina. A number of transitional alumina structures can form
6
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