Tech Briefs

A set of lecture slides describes an investigation of creep forming as a means of imparting desired curvatures to initially flat stock plates of carbon-reinforced ceramic-matrix composite (C-CMC) materials. The investigation is apparently part of a continuing effort to develop improved means of applying small CCMC repair patches to reinforced carbon- carbon leading edges of aerospace vehicles (e.g., space shuttles) prior to reentry into the atmosphere of the Earth.

According to one of the slides, creep forming would be an intermediate step in a process that would yield a fully densified, finished C-CMC part having a desired size and shape (the other steps would include preliminary machining, finish machining, densification by chemical vapor infiltration, and final coating). The investigation included experiments in which C-CMC disks were creep-formed by heating them to unspecified high temperatures for time intervals of the order of 1 hour while they were clamped into single- and double- curvature graphite molds. The creep-formed disks were coated with an oxidation-protection material, then subjected to arc-jet tests, in which the disks exhibited no deterioration after exposure to high-temperature test conditions lasting 490 seconds.

This work was done by Wallace L. Vaughn and Stephan J. Scotti of Langley Research Center, Melissa P. Ashe of Swales Aerospace, and Liz Connolly of General Electric Co.

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Creep Forming of Carbon-Reinforced Ceramic-Matrix Composites (reference LAR-17289-1) is currently available for download from the TSP library.

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