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“Brittle” Composite Claims Found Obvious

00-1502
May 25, 2001

Decision icon Decision

Last Month at the Federal Circuit - June 2001

Judges: Bryson (author), Michel, and Rader

In In re Petrak, No. 00-1502 (Fed. Cir. May 25, 2001) (nonprecedential decision), the Federal Circuit held that the Board had not erred in concluding that certain application claims were unpatentable as being obvious in view of U.S. Patent No. 4,642,271 to Rice (“Rice”) and U.S. Patent No. 4,746,480 to Clark (“Clark”).

Petrak’s patent application is directed to an oxidation-resistant ceramic composite that includes a ceramic matrix formed by a curable polymer and sealant oxide coated on the surface of the composite.

During prosecution, the Examiner rejected certain claims as being obvious over Rice in combination with Clark. The Board agreed with the Examiner that Rice discloses a ceramic matrix formed by the ceramification of a preceramic composition comprising a curable polymer and, within the ceramic matrix, a refractory fiber coated with a material that provides an interface between the refractory fiber and the ceramic matrix. The Board also agreed that Clark discloses an in-situ formed sealant-oxide coating on the surfaces of ceramic fibers. In addition, the Board agreed that one of skill in the art would read Clark to suggest that similar results could be obtained by using an in-situ formed sealant-oxide coating on the surfaces of ceramic matrices consisting of material identical to the coated fibrous material of Clark. Finally, the Board found that motivation to combine Rice and Clark arose from the teachings of the references themselves and the level of skill in the art.

The Federal Circuit agreed that three pieces of evidence sufficiently supported that Rice and Clark taught a “curable preceramic polymer.” First, Rice disclosed that a wide variety of ceramic matrix compositions may be used. Second, Clark states that organosilicon preceramic polymers are well known in the art and can be cured and pyrolyzed to ceramic form. Third, Petrak’s own specification notes that curable preceramic polymers are known in the art and can be manufactured by known techniques. Therefore, the Federal Circuit found that this evidence was sufficient to support the Board’s findings.

With regard to the in-situ formed sealant-oxide coating limitation, Petrak argued that Clark does not disclose or teach the use of an in-situ formed sealant-oxide coating on the surfaces of a composite as opposed to the surfaces of a fiber. In particupage lar, Petrak asserted that the Board was incorrect to
rely on the Examiner’s statement that one of ordinary skill in the art would expect similar results on a ceramic-matrix surface consisting of material identical to the coated fibrous material of Clark.

However, Petrak conceded that Clark’s fibers were identical material to the claimed composite. Thus, the Federal Circuit concluded that substantial evidence supported the Board’s findings.

Petrak also contended that the Board had erred in finding a motivation to combine Rice and Clark. However, the Board noted that both Rice and Clark taught that exposure of a composite to high temperature oxidizing conditions may result in embrittlement, and Clark offered a solution to this embrittlement problem. Therefore, the Federal Circuit concluded that the Board was correct in concluding that there was motivation to combine Rice and Clark and that Petrak’s claims are obvious.