镀层碳纤维增强铜基复合材料的制备及其性能研究

采用化学镀工艺分别在碳纤维表面施加Cu层、Ni层或Cu+Ni镀层,对不同镀层碳纤维进行900℃热处理,使用真空热压烧结方法制备不同镀层碳纤维增强铜基复合材料。通过光学显微镜、扫描电子显微镜、能谱分析仪和X射线衍射仪对复合材料组织形貌、界面元素分布和物相进行分析,并对复合材料的物理及力学性能进行测试。结果表明,经过900℃高温处理,镀Cu层对碳纤维结构无影响,镀Ni层会造成碳纤维结构向石墨结构发生转变,在碳纤维表面Cu+Ni镀层可以有效地降低碳纤维发生结构转变。Cu+Ni镀层碳纤维增强的铜基复合材料较Cu镀层碳纤维及Ni镀层碳纤维增强的铜基复合材料具有更高的显微硬度和压缩强度,但导电性略低于镀Cu碳纤维增强的铜基复合材料。

含Fe、Ni的CF/Cu复合材料

用连续电镀法在碳纤维上镀铜后又镀Fe、Ni,制备了镀Cu-Fe、Cu-Ni的双镀层碳纤维。用它们分别制备了CF/Cu-Fe、CF/Cu-Ni复合材料,与V_t相近的CF/Cu复合材料相比,CF/Cu-Fe,CF/Cu-Ni复合材料的电阻率和弯曲强度均有不同程度的提高。通过调整碳纤维的体积分数V_f,复合材料的热膨胀系数可以明显降低。 单向复合材料在断裂后,碳纤维没有明显拔出,CF/Cu-Ni复合材料的断口上,基体出现塑性变形,CF/Cu-Fe复合材料断口上的碳纤维表面上分布着不连续的瘤状物。 用透射电镜分析了这两种复合材料的界面结构。CF/Cu-Fe复合材料中碳纤维表面上的不连续瘤状物是多晶的Fe_3C相,CF/Cu-Ni复合材料的界面区则是Cu-Ni固溶体相。它们对碳纤维与铜基体的结合分别起着反应型和溶解型的强化作用。

Catalytic graphitization of polyacrylonitrile(PAN)-based carbon fibers with Fe-Cr_2O_3 composite coating

The process of electrodepositing Fe-Cr2O3 composite coating on polyacrylonitrile （PAN）-based carbon fibers and its catalytic graphitization were studied. Carbon fibers with and without electrodeposited Fe-Cr2O3 composite coating were heat treated at different temperatures and the structural changes were characterized by XRD, Raman spectroscopy and SEM. The results indicate that Fe-Cr2O3 composite coating exhibits a significant catalytic effect on graphitization of carbon fibers at low temperatures. When the Fe-Cr2O3-coated carbon fibers were heat treated at 1 300℃ the interlayer spacing （doo2） and ratio of relative peak area （AD/AG） reach 3.364/k and 0.34, respectively. Whereas, the extent of graphitization of pristine carbon fibers is comparatively low even after heat treatment at 2 800℃ and the values of doo2 and AD/AG are 3.414 A and 0.68, respectively. The extent of graphitization of carbon fibers increases not only with the increase of the catalyst gross but also the Cr2O3 content in Fe-Cr2O3 coating. The catalytic effect of Fe-Cr2O3 composite coating accords with the dissolution-precipitation mechanism.