论文部分内容阅读
以甲基三氯硅烷为原料,采用催化化学气相沉积(CCVD)工艺在短切碳纤维(C_(fd))表面制备了纳米SiC纤维(nano SiC_f)改性层,并采用凝胶注模-无压烧结工艺制备了nano SiC_f-C_(fd)/Si_3N_4和C_(fd)/Si_3N_4复合材料。使用矢量网络分析仪研究了nano SiC_f-C_(fd)和C_(fd)对Si_3N_4陶瓷在X波段(8.2~12.4GHz)的介电响应和吸波性能的影响。结果表明:nano SiC_f-C_(fd)/Si_3N_4和C_(fd)/Si_3N_4复合材料的复介电常数和介电损耗角正切值(tanδ)均随纤维添加量增加而增大;相同纤维含量时,nano SiC_f-C_(fd)/Si_3N_4复合材料的介电常数实部比C_(fd)/Si_3N_4复合材料有所降低,但损耗角正切升高。反射损耗结果表明:nano SiC_f-C_(fd)/Si_3N_4复合材料拥有更优的电磁波吸收效果。nano SiC_f-C_(fd)含量为2wt%、d=2.5mm时,出现最大吸收峰-14.95dB,反射损耗优于-5dB,波段频宽达3.5GHz。nano SiC_f界面改性能有效提高C_(fd)/Si_3N_4复合材料的吸波性能。
A modified layer of nano SiC fiber (nano SiC_f) on the surface of chopped carbon fiber (C_ (fd)) was prepared by catalytic CCVD using methyltrichlorosilane as raw material. Nano SiC_f-C_ (fd) / Si_3N_4 and C_ (fd) / Si_3N_4 composites were prepared by pressure sintering. The influence of nano SiC_f-C_ (fd) and C_ (fd) on the dielectric response and microwave absorbing property of Si_3N_4 ceramic in X-band (8.2 ~ 12.4GHz) was investigated by using vector network analyzer. The results show that both the complex permittivity and the tanδ of nano SiC_f-C_ (fd) / Si_3N_4 and C_ (fd) / Si_3N_4 composites increase with the increase of the fiber content. At the same fiber content , the real part of the dielectric constant of nano SiC_f-C_ (fd) / Si_3N_4 composite is lower than that of C_ (fd) / Si_3N_4 composite, but the loss tangent increases. The results of reflection loss show that nano SiC_f-C_ (fd) / Si_3N_4 composite has better electromagnetic wave absorption effect. When the content of nano SiC_f-C_ (fd) is 2wt%, d = 2.5mm, the maximum absorption peak is -14.95dB, the reflection loss is better than -5dB and the bandwidth of the band is 3.5GHz. The nano SiC_f interface modification can effectively improve the microwave absorbing performance of C_ (fd) / Si_3N_4 composite.