The Study Of Laser-induced Graphitization Of Pan-based Carbon Fibers And Its Reactive Molecular Dynamics Simiulations

Carbon fibers are widely focused for its extremely excellent properties.In particular,high-modulus carbon fibers are favored in space exploration.At present,the development of high-modulus carbon fibers is in the bottleneck,improving the modulus with high difficult and the cost remaining high,which greatly limits its application in other fields.In this study,research status of carbon fibers and interaction between laser and carbon fibers were reviewed at first.Next,executable schemes were proposed,according to two methods,heating with higher temperature and inducing by graphite-like structures,which can effectively improve carbon fiber's elastic modulus.Finally,experiments and simulations were carried out.What coming up with in this paper mainly as following:1.The experiment platform for laser-induced graphitization of carbon fibers was built and related experiments also were carried out.And then,the samples' micro-structure by Raman and XRD,surface morphology by SEM and tensile properties of single fiber were tested.All traits getting from the tests in this study indicated the effectiveness of laser-induced graphitization of PAN-based carbon fibers.2.The difference between laser-induced and traditional heat-induced carbonization process of carbon fibers by reactive molecular dynamics simulation were studied.In the carbonized process,laser with the capacity of heating rapidly brings shock-force to the irradiated fibers,which can amplify the fluctuation of the molecules,and then increasing the probability of reacting or colliding with other atoms,forming more graphite-like structures at last.3.The insights into the mechanisms of graphene "templating" for the carbonization of PAN-based carbon fibers by reactive molecular dynamics simulations were also investigated.In this work,the removed process of non-carbon atoms and the formation mechanisms of graphite lamellar structure,both induced by nano-graphene structures,from the dimension of active atoms were elucidated.Also,his study provided a reasonable explication on the beneficial results,i.e.incorporation of a small amount of nano-graphene structures significantly improved graphitic order and orientation in continuous PAN-based carbon fibers upon carbonization at relatively low temperatures.