DENSITY, MICROSTRUCTURE AND PROPERTY OF LARGE-SCALE CARBON/CARBON COMPOSITES PREPARED BY FAST THERMAL GRADIENT CVI

摘要

Carbon/carbon (C/C) composites are considered as new high-temperature thermal structural materials. It processes low density, high specific strength, and good friction properties etc, especially excellent strength retention at super-high temperature. They are mainly used in aviation and spaceflight fields, such as heat shields, nose tips and leading edges of re-entry vehicles, aircraft brakes. The preparation technology of C/C composites is always a hotspot theme. At present, chemical vapor infiltration (CVI) is the most important technology for them. However, densification of C/C composites by traditional isothermal CVI needs hundreds of hours, which causes high cost and limits their applications. The other new rapid densification technologies (FCVI, TG-CVI, CLVI, etc.) remain many disadvantages in application. Densification rate is affected severely by the size and shape of performs. A suitable method is active demand for C/C composites in industrial field. In the work, Φ80mm x 400mm solid cylindrical large scale 2D-C/C composites were fast prepared within 100 hours by thermal gradient CVI. The distribution of density, microstructure and the flexural property are studied. Thermal gradient CVI is confirmed as a potential technology for C/C composites.