原位气相生长碳纳米纤维改性炭/炭复合材料研究

Study on C/C composites modified by in-situ vapor-grown carbon nanofibers

采用化学气相沉积(CVD)法在不同密度的炭/炭复合材料表面原位生长碳纳米纤维(CNFs),探究不同工艺参数对CNFs微观形貌的影响规律,寻求最优化工艺。以原位生长CNFs改性C/C复合材料和纯C/C复合材料为研究对象,描述了CNFs的生长机制,并分别对2种试样进行石墨化度、力学性能和导热性能的检测分析,研究CNFs增强C/C复合材料性能的改性机理。结果表明:当催化剂前驱体Ni(NO_3)_2溶液的浓度为0.10 mol/L,裂解温度为650~700℃,反应时间为30~45 min时,所制备的CNFs直径细小均匀,一般为30~60 nm,长径比大,呈网状分布,分散性好。相同密度下,CNFs-C/C复合材料的弯曲强度达到166.29 MPa,比纯C/C复合材料(131.73 MPa)提高了26.2%,弯曲性能显著提升。原位生长CNFs改性C/C复合材料的室温z轴热导率为14.50 W/(m·K),是纯C/C复合材料的1.85倍。

Carbon nanofibers（CNFs） were in situ grown on the surface of carbon/carbon composites with different density by chemical vapor deposition （CVD）. In order to seek the optimal process, the influences of different parameters on the CNFs mierostructure were investigated and discussed. Using the C/C composites modified by in-situ grown CNFs and pure C/C composites as the research objects, the growth mechanism of in-situ grown CNFs was described and the graphitization degree,the mechanical properties and thermal conductivity of two samples were respectively tested and analysed to study the modification mechanism of CNFs reinforced C/ C composites. The results show that the CNFs prepared with the Ni（NO3）2 solution concentration of 0.10 mol/L as catalyst precursor heated at 650~700℃ for 30~45 min have many advantages, the diameter is small and uniform in 30-60 nm, length to diameter ratio is large, and the dispersibility is good. Under the same density, the bending strength of CNFs-C/C composites reached to 166.29 MPa, which was higher 26.2% than that of pure C/C composites （131.73 MPa）. Therefore, the bending performance of CNFs-C/C composites was significantly improved. The room temperature z direction thermal conductivity of in-situ grown CNTs modified C/C composites is about 14.50 W/（m·K） ,which is 1.85 times that of pure C/C composites.