(d) diffusing ammonia into the impregnated mat by exposing the mat to a
flowing ammonia environment and, thereafter, subjecting the mat to an
ammonia soak time in a quiescent ammonia atmosphere sufficient to
convert the sol to gel to produce a consistent microstructure throughout
the mat;
(e) drying the mat to produce the ceramic insulation; and
(f) heat treating the mat to increase its tensile strength.
31. Ceramic insulation having a density of about 8-25 lb/ft obtainable by:3
(a) forming a slurry of ceramic components selected from the group consisting
of ceramic fibers, ceramic microparticles, and mixtures thereof, and a
binding amount of metal powder;
(b) optionally, adding fugitive microballoons or ceramic whiskers or both to
the slurry;
(c) molding the slurry to form a mat;
(d) converting the metal powder to an oxide or nitride to form bonds between
the ceramic components, the metal being between about 5-50% of the
weight of the ceramic components.
Claims presented in product-by-process format are treated, for the purpose of patentability, as
claims to the product. In re Thorpe, 777 F.2d 695, 697, 227 USPQ 964, 966 (Fed. Cir. 1985); In re
Pilkington, 411 F.2d 1345, 1348, 162 USPQ 145, 147 (CCPA 1969). Where the product specified in
a product-by-process claim appears to be identical to a product in the prior art, even though made by a
different process, the product may be rejected and the burden falls on the applicant to show that the
products differ in an unobvious way. In re Marosi, 710 F.2d 799, 803, 218 USPQ 289, 292-93 (Fed.
Cir. 1983); In re Best, 562 F.2d 1252, 1255, 195 USPQ, 430, 433-34 (CCPA 1977); In re Brown, 459
F.2d 531, 535, 173 USPQ 685, 688 (CCPA 1972). In other words, in considering the patentability of
a product-by-process claim, the product described by the claim is not considered limited by the process
set out in the claims. Scripps Clinic & Research Foundation v. Genentech Inc.; 927 F.2d 1565, 1583, 18
USPQ2d 1001, 1016 (Fed. Cir. 1991). This precedent, however, does not mean that process limitations
in the claim are totally irrelevant. Where the process limitations impart characteristics or properties to the
product, not shared with or suggested by the prior art product, a rejection would be inappropriate. Thus,
a heat treating step which changes the properties to the product would distinguish the product from the
unheat-treated prior art product.
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