高温下压力对聚丙烯腈基碳纤维结构的影响

Effect of Pressure on Structure of PAN-based Carbon Fibers at High Temperature

以东丽T300-1K平纹编织碳布为原料,利用放电等离子烧结技术(SPS)在1750℃高温下对碳纤维布施加垂直于纤维轴向的压力,制备了不同烧结压力的碳纤维样品,利用扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、傅里叶红外光谱(FT-IR)、拉曼光谱(Raman)、X射线衍射仪(XRD)对制备的碳纤维样品的微观形貌和微观结构进行了表征,并利用图像处理手段对纤维截面圆度进行了分析。结果表明,高温下施加的垂直于纤维轴向的压力将使碳纤维的微观形貌和结构发生变化。随着压力的增加,碳纤维的圆形截面趋于扁平化,截面圆度从0.91减小到0.65,(002)晶面衍射峰半高宽逐渐减小,其晶面间距由0.3544 nm减小到0.3488 nm,沿纤维石墨网方向的微晶尺寸从3.483 nm长大到10.682 nm。Raman图谱的D峰和G峰强度比逐渐减小,纤维的石墨化程度增加。在1750℃高温下,随着压力增加,碳纤维内部微观结构由无序的二维乱层石墨结构向有序的三维层状发展。

Carbon fiber(CF)samples sintered at different pressures were prepared by using spark plasma sintering(SPS)at 1750℃,with the Toray T300-1 K plain woven carbon cloth as raw materials.Scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),Fourier transform infrared spectroscopy(FT-IR),Raman spectroscopy(Raman)and X-ray diffraction(XRD)were used to characterize morphology and microstructure of the samples,while the roundness of the fiber section was analyzed by using image processing.It was found that the pressure applied perpendicularly to the fiber axis at high temperatures would change the morphology and structure of the CF.With increasing pressure,the circular cross section of the CF tends to be flattened,the roundness of cross section was decreased from 0.91 to 0.65,the FWHM of(002)diffraction peak was decreased gradually,the crystal plane spacing was decreases from 0.3544 nm to 0.3488 nm,and a the microcrystalline size of CF long the direction of the fiber graphite mesh grew from 3.483 nm to 10.682 nm.The intensity ratio of D peak to G peak in the Raman spectrum was decreased gradually and the degree of graphitization of the fiber was increased.At 1750℃,with increasing pressure,the internal microstructure of the CF was developed from two-dimensional disordered graphite structure to ordered three-dimensional layered structure.