螺旋形碳纤维渗硅和渗氮（硼、铝、镍）机理及其复介电常数频散效应研究

The coiled carbon fibers were prepared by catalyzed pyrolysis of acetylene via the plate method. The nanocrystal lattice elements doped coiled SiC fibers were synthesized by infiltration of silicon, nitrogen, aluminium and nickel elements into coiled carbon fibers. The nanocrystal lattice elements doped coiled SiC fiber microwave absorbent consists of nano SiC crystals doped with nitrogen, boron, phosphorus or aluminium elements, which would be used as high temperature microwave absorbent. This new kind of microwave absorbent composed of nano SiC doped with N, P, Al or Ni elements have nano effects and properties of chirality because of the special coiling morphology. The nano SiC doped with N, P or Al elements is a good candidate for high temperature microwave absorbent. The coiled SiC fiber absorbent composed of crystal lattice doped nano SiC introduces the chiral parameters into the microwave absorbing material optimizing design, which is easily to match the impedance of free-space. The complex permittivity of the nanocrystal lattice elements doped coiled SiC fiber exhibited a good frequency response characteristic at 2-18 GHz. It’s very necessary to systematically investigate the crystal lattice doping of the coiled SiC fiber to reveal the mechanism of the frequency response and the dependence of complex permittivity on frequency in the nanocrystal lattice doped coiled SiC fiber. The microwave absorbing materials with excellent properties will be fabricated by increasing the frequency response of the complex permittivity in the nanocrystal lattice doped coiled SiC fiber.

通过催化裂解反应用基板法制备螺旋形碳纤维，在螺旋形碳纤维中渗硅和渗氮（硼、铝、镍），制备出晶格掺杂螺旋形SiC纤维吸收剂。晶格掺杂螺旋形SiC纤维吸收剂是由掺杂N、B、Al、Ni等元素的SiC纳米晶构成的螺旋形纤维，将晶格掺杂的纳米SiC吸收剂与螺旋形手征吸收剂有机融为一体，构成一类新型的纳米效应与手征特性复合的耐高温吸收剂。研究螺旋形碳纤维渗硅和渗氮（硼、铝、镍）过程中Si、N、B、Al、Ni等元素在螺旋形碳纤维内的扩散过程，晶格掺杂N、B、Al、Ni纳米SiC的形成机理，及其手征参数与复介电常数频散效应的相关性和响应机制，进一步探讨其介电性能的高温响应行为与机制。晶格掺杂螺旋形SiC纤维吸收剂的复介电常数在2-18GHz范围内有明显的频散效应，在很窄频率范围内，出现如此大的频散效应此前鲜有报道，需对螺旋形碳纤维进行系统的渗硅和渗氮（硼、铝、镍）机理研究，揭示复介电常数频散效应的机理。

用基板法通过催化裂解反应制备了螺旋形碳纤维，通过在螺旋形碳纤维中渗硅和渗氮（硼、铝、镍），制备出了晶格掺杂螺旋形SiC纤维吸收剂。晶格掺杂螺旋形SiC纤维吸收剂是由掺杂N、B、Al、Ni等元素的SiC纳米晶构成的螺旋形纤维，将晶格掺杂的纳米SiC吸收剂与螺旋形手征吸收剂有机融为一体，构成一类新型的纳米效应与手征特性复合的耐高温吸收剂，提出了螺旋形SiC纤维中晶格掺杂N、B、Al、Ni纳米SiC的形成机理。研究了晶格掺杂螺旋形SiC纤维吸收剂在2-18GHz的微波电磁参数，发现其复介电常数具有显著的频散效应，提出了晶格掺杂螺旋形SiC纤维产生显著频散效应的机理，建立了晶格掺杂N、B、Al、Ni纳米SiC的晶体结构模型，把制备的晶格掺杂螺旋形SiC纤维作为微波吸收剂，制备了在高温具有优异吸波性能的夹芯复合材料。