不同初始结构碳纤维石墨化进程趋同性研究

为优化碳纤维的石墨化工艺,利用拉曼光谱对碳纤维在石墨化过程中的结构变化进行了研究,分析比较了两种碳纤维石墨化进程的异同.结果表明:纤维在高温下发生脱氮与石墨化转变反应,脱氮反应会在石墨微晶中留下分子级空洞,氮原子脱除越多,微晶内空洞越多;石墨化转变促使石墨微晶生长、结构完善.两种纤维氮元素含量不同造成其初始结构不同,氮含量越低,纤维石墨化程度越高.氮原子脱除程度不同引起两种纤维石墨化进程存在差异,热处理温度高于1 800℃时,不同初始结构碳纤维中的氮原子都脱除完全,纤维中碳化学结构趋于相同,石墨化进程出现趋同性.

Research on convergence of graphitization with different initial structural carbon fibers

To optimize the graphitization technology of carbon fibers,Raman spectroscopy was employed to characterize the microstructure of PAN-based carbon fibers during high temperature heat treatment,and graphitization process for two kinds of carbon fibers was analyzed and compared.The results show that the variety of carbon fibers’ structures can be represented by Raman spectroscopy parameters,such as the Raman shifts and full width at half maximum of main D and G bands.Denitrogenation induced defects,the more the amount of escaped N,the more the defects in the graphite layers.Decfects were reduced by graphitization.The difference of the N content resulted in the structural differences between the two kinds of carbon fibers.When the heat treatment temperature was higher than 1 800 ℃,N would escape completely,and the structure for the two kinds of carbon fibers would be similar.Different initial structural carbon fibers achieved the convergence of graphitization process.