模板法制备MoSi_2/竹炭复合材料及吸波性能

Absorbing performance of MoSi_2/BC composites using bamboo charcoal template

以竹材炭化的多孔竹炭(BC)为模板,金属间化合物二硅化钼(MoSi_2)为吸收剂,采用包埋硅(Si)粉固相烧结工艺制备MoSi_2/BC多孔复合吸波材料。利用XRD、SEM和矢量网络分析仪对MoSi_2/BC复合材料的物相组成、显微结构、介电和吸波性能进行表征。结果表明:在氩气(Ar)保护气氛下,1450℃烧结制备的MoSi_2/BC复合材料主要含物相MoSi_2、SiC及无定型碳。BC基体孔隙内除分布有MoSi_2外,还布满排列无序、尺寸长短不一、相互交叉呈网状的碳化硅晶须(SiC_W),SiC_W的存在可有效提高复合材料电磁波吸收性能。在8.2～12.4GHz频率范围内,与环氧树脂混合后,复合材料反射率随MoSi_2/BC含量增加而逐渐减小。MoSi_2/BC含量为50%(质量分数)时,随试样厚度增加反射率降低,且最小反射率向高频方向移动;在11.87GHz处最低反射率为-13dB,反射损耗小于-10dB带宽约达1.0GHz,具有良好的吸波性能。

Using the bamboo charcoal(BC) material as the template, the metallic chemical compound MoSi2.as the absorption catalyst, the MoSi2/BC porous composite materials were fabricated by the embedded solid reaction sintering method. The components, microstructure and dielectric constant of the MoSi2/BC composite material were detected by XRD, SEM and vector network analyzer respectively. The results show that in the argon protective atmosphere(Ar), at the sintering temperature of1450℃, the phase composition of MoSi2/BC composite material primarily consists of MoSi2, SiC and amorphous carbon. In the pores of the bamboo charcoal, the SiC whiskers(SiC W) are distributed in an irregular way with different size and length, furthermore to form an intersecting network except MoSi2.particles. The existence of SiC W can significantly improve the wave absorption ability. At the range of 8.2-12.4GHz, after mixed with epoxy resin, the reflection losses of the composites of MoSi2/BC are gradually decreased with the increase of MoSi2/BC content. With the increase of sample thickness at the MoSi2/BC 50%(mass fraction) content, the minimum absorption peak of reflection loss is moving to the low frequency. The composites’ lowest reflection loss is -13dB at11.87GHz, and the reflection bandwidth value below -10dB is around1.0GHz.This ind- icates that the MoSi2/BC composites possess perfect microwave absorbing performance.