Low-cost Manufacturing of Carbon Fibers Using Laser Processing

碳纤维具有较高的比刚度和比强度，是轻量化结构的重要工程材料。碳纤维已被证明在土木工程建设、航空航天领域、汽车系统、体育器材等方面发挥着重要作用，用碳纤维复合材料替代乘用车车身外壳核心结构中的金属，可使车辆重量减轻60%。这可以节省燃料，减少二氧化碳排放，对能源消耗和环境产生积极影响。然而，碳纤维还没有被广泛应用于各种系统，特别是汽车系统。最大的障碍是碳纤维制造成本过高。该奖项支持低成本制造碳纤维的新制造工艺的基础研究。与目前的碳纤维制造工艺相比，新工艺有可能大幅缩短加工时间，实现高能效，降低制造成本，并改善碳纤维的性能。这项研究成果将使碳纤维作为轻质和坚固的工程材料在广泛的应用中得到更广泛的使用。制造碳纤维的新工艺使用激光加工将稳定的聚丙烯腈前驱体纤维转化为碳纤维(碳化)，将碳纤维转化为石墨纤维(石墨化)。研究目的是了解激光加工参数(激光波长、功率、模式、扫描速度和光束分布)对纤维微观结构和力学性能的影响。为了实现这一目标，将使用波长为10.6微米的CO2激光器和波长为532 nm的固体激光器进行实验。激光功率(小于5W)、激光模式(连续或脉冲)和扫描速度(高达25厘米/S)将有所不同。将调整激光光束轮廓，以引入预热并控制光纤中的温度分布。纤维的典型长度将在30厘米以内，典型的直径约为7微米。将使用电子显微镜观察纤维的微观结构，并根据结合状态(通过FTIR和拉曼显微镜测量)和结晶度(通过X射线衍射)进行评估。纤维的力学性能(拉伸强度、弹性模数和破坏应变)将由动态力学分析仪测量。

Carbon fibers are important engineering materials for lightweight structures due to their high specific stiffness and strength. It has been demonstrated that carbon fibers play an important role in civil engineering construction, aerospace field, automotive systems, athletic equipment, etc. Using carbon fiber composites to replace metals used in core structures of body shells in passenger automobiles can reduce vehicle weight by as much as 60%. This can result in fuel savings and less carbon dioxide emissions, having positive impacts on energy consumption and the environment. However, carbon fibers have not been widely used in various systems, especially automotive systems. The largest obstacle is the high cost of carbon fiber manufacturing. This award supports fundamental research on a new manufacturing process for fabricating carbon fibers with low cost. Compared with the current carbon fiber manufacturing process, the new process can potentially dramatically shorten the process time, achieve high-energy efficiency, lower manufacturing cost, and improve properties of carbon fibers. Results from this research will enable the wider use of carbon fibers as lightweight and strong engineering materials in broad applications.The new manufacturing process for fabricating carbon fibers uses laser processing to convert stabilized polyacrylonitrile precursor fibers to carbon fibers (carbonization) and carbon fibers to graphite fibers (graphitization). The research objective is to understand the effects of laser processing parameters (laser wavelength, power, mode, scan speed, and beam profile) on fiber microstructure and mechanical properties. To achieve this objective, experiments will be conducted using a CO2 laser with wavelength of 10.6 micrometer and a solid-state laser with wavelength of 532 nm. Laser power (less than 5 W), laser mode (continuous or pulsed), and scan speed (up to 25 cm/s) will be varied. Laser beam profile will be adjusted to introduce preheating and control temperature distribution in the fiber. The typical length of the fibers will be within 30 cm, and typical diameter around 7 micrometer. Fiber microstructure will be observed by using electron microscopy and evaluated in terms of bonding status (measured by FTIR and Raman microscopy) and crystallinity (by X-ray diffraction). Mechanical properties (tensile strength, modulus, and failure strain) of fibers will be measured by dynamic mechanical analyzer.