Mechanical properties in compression of CVI-densified porous carbon/carbon composite

Compressive properties of a porous 2-D planar-random carbon/carbon (C/C) composite preform densified by chemical vapour infiltration (CVI) of pyrolytic carbon were determined and compared to those obtained previously for similar C/C composite densified using a non-CVI technique. Stress/strain curves and failure modes of the CVI composite were similar to those seen in the non-CVI C/C composite. For specimens of equivalent density, the CVI technique resulted in improved in-plane properties, but inferior out-of-plane properties, when compared to the non-CVI composite. Compressive property anisotropy ratios for the CVI composite were slightly reduced compared to the uninfiltrated preform state whilst comparison between compressive and (previously determined) flexural properties showed general agreement. A microstructural model of the composite developed by the authors was used to explain the results. (C) 1999 Elsevier Science Ltd. All rights reserved.