碳纤维具有低密度、高模量及高力学强度等优势,是常见的复合材料增强体。通过表面改性的方式,实现碳纤维表面纳米碳材料的有效复合,可获得更优的材料性能。而目前常见的制备方法,可能存在催化剂引入过程损伤纤维、反应时间长等缺点。因此,探索工业化大规模负载纳米尺度碳材料的制备工艺十分必要。采用商用镀镍碳纤维为原料,通过调节化学气相沉积法(CVD)参数,实现不同形貌碳纳米纤维(CNFs)在镀镍碳纤维表面的有效负载,通过SEM、EDS和TEM等表征方式,结合扩散理论和V-S-L模型,分析催化剂厚度对催化剂形态的影响及CVD参数对各形貌产物的影响机理。结果表明,当催化剂层较厚时,催化剂以连续的片状形态存在,主要控制因素为热失配而非表面张力。H2比例较高时,反应以扩散为主导,形貌趋向于催化剂位于中间的粗大CNFs阵列;H2比例较低时,反应以催化为主导,形貌趋向于具有夹层的CNFs团簇。
Carbon fiber has the advantages of low density,high modulus and good mechanical strength,making it a common reinforcement in composites materials.By surface modification,it can realize the effective combination of carbon nanomaterial on carbon fiber surface and markedly improve the material properties.However,the current typical preparation process may have disadvantages such as damage to fibers during the introduction of catalysts and long reaction time,etc.Therefore,it is necessary to explore the industrialized and large-scale preparation method of loading carbon nanomaterial on fiber surface.In this study,we selected commercial nickel-plated carbon fiber as raw material to realize the growth of two different morphology CNFs on nickel-plated fiber surface by adjusting the parameters of chemical vapor deposition (CVD) process.Scanning electron microscopy (SEM),Energy Dispersive Spectroscope (EDS) and transmission electron microscopy (TEM) were utilized to characterize the structure and morphology.Diffusion theory and V-S-L model were applied to analyze the influence of catalyst thickness on catalyst morphology and the impact mechanism of CVD parameters on various morphologies of products.The results indicated that when the catalyst layer was thicker,the catalyst existed in continuous sheets and the main controlling factor was thermal mismatch rather surface tension.When the ratio of H2 was higher,the reaction was dominated by diffusion and the morphology tended to the coarse CNFs array with the catalyst in the middle.On the contrary,when the ratio of H2 was lower,the reaction was dominated by catalysis and the morphology tended to the CNFs clusters with nickel carbide interlayer.
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