Ablation and oxidation resistance properties of C/C composites densified by xylene pyrocarbon using LaCl3 as a catalyst and resin carbon

Publication date: October 2018Source: New Carbon Materials, Volume 33, Issue 5Author(s): Hai-liang DENG, Jin-huang ZHENG, Jun-ning CAO, Dong-mei YAO, Hong CUI, Xiao-hu ZHANG, Hong SUAbstractCarbon/carbon composites with densities of 1.72-1.73 g/cm3 were prepared by densification with pyrocarbon produced from xylene using a LaCl3-catalyzed film boiling chemical vapor infiltration method, followed by resin impregnation, carbonization and graphitization. The ablation and oxidation resistance of the composites were respectively tested by an oxyacetylene torch and air oxidation methods. The phase composition and morphology of the ablated and oxidized surfaces were studied by XRD and SEM, respectively. Results show that the ablation rate and oxidation loss exhibit minima at catalyst contents from 0 to 15 wt%. During the ablation and oxidation, the La2O3 film formed from LaC2 oxidation protects the composites from further oxidation. Catalyticallyformed carbon nanofilaments prevent mechanical separation of the carbon fibers from the matrix. As a result, mass ablation and volume ablation rates and the weight loss of the composites due to oxidation are decreased by 7. 6%-15. 2%, 10. 7% −20. 0% and 17.7%-38. 5%, respectively compared with those formed without the catalyst. The composites produced at catalyst contents of 6 and 10 wt% have higher ablation and oxidation resistance than samples with 0, 3 and 15 wt% contents. Both the thicker isotropic pyrocarbon when the catalyst content ...
Source: New Carbon Materials - Category: Chemistry Source Type: research