Laser Irradiation of Carbon Fibers and Composites.

摘要

The use of carbon-carbon composites as reentry vehicle nose tips has increased due to their unique thermochemical and thermostructural properties. One performance criterion of particular importance to the aerospace community is the ablation behavior. Since a large number of candidate composites is available, a preliminary screening test was sought which could select the most promising fibers and composites. Therefore, the objective of this program was to irradiate various carbon/graphite filaments, bulk pitch matrices, carbon-carbon composites and pyrolytic graphite to characterize mass loss and structural changes. The laser irradiation experiments have provided an insight into the microstructural mechanisms of ablation. They have shown that correlations exist between mass loss and material properties, that differences exist in mass loss characteristics between composite constituents, and that ablation testing results in similar correlations. It was concluded that laser irradiation of reentry nose tip materials can be used to investigate the behavior of carbonaceous materials in an ablation environment. (Author)