Study On Bamboo Charcoal(BC)-based Composites Prepared By Biological Template Method And Their Wave Absorbing Properties

With the rapid development of information technology and the wide application of electromagnetic wave,people has paid much attention to the subject of high efficiency new electromagnetic absorption materials.Porous bamboo charcoal is a new kind of carbon material with certain shielding effect;it has unique electrical properties,large specific surface area and disordered structures of the channel.Due to the advantages of large losses and light weight,porous bamboo carbon materials provide a basis for developing new kinds of electromagnetic absorbing materials.Based on the above discussion,the aim of this paper is to fabricate efficient electromagnetic absorbing materials by adjusting the characteristics of bamboo charcoal and adding other absorbents to control its electromagnetic parameters.According to the Raman spectra and dielectric constant test results of bamboo charcoal under different temperatures?700?,800?,1000?,1200??,the 800?bamboo charcoal shows the excellent performance,so it has been choosed as raw materials for the preparation of composite material.The BC/Si C composites were prepared by means of extraction and embedding in bamboo charcoal channel.The relationship between the interface change of BC/SiC composites and the complex dielectric constant was analyzed.The thickness of BC/Si C composite material was 2.5mm,and the lowest reflection coefficient was-10.16dB at 10.7GHz.The effective absorption bandwidth of the reflection coefficient<-8dB is 2.1 GHz.The BC/MoSi₂?BC/Al₂O₃ composites were prepared by means of embedding.The Dielectric loss mechanisms of the composite material were analyzed.The reflectivity of the samples within x-band was calculated based on the transmission line theory,the result shows that BC/MoSi₂and BC/Al₂O₃ composites have excellent dielectric properties and microwave absorbing performance.The thickness of BC/MoSi₂and BC/Al₂O₃ composites was 2.5mm,the optimal reflection loss of BC/MoSi₂ composite was up to-12dB at 9.8 GHz,and the optimal reflection loss of BC/Al₂O₃ composite material was up to-21.2dB at 9.1GHz.What's more,the wider absorption band of the reflection loss could be achieved above-15d B in the8.5¹0GHz region.The SiC/MoSi₂ composite materials were prepared by embedding and permeating method with a bamboo charcoal template for the preparation of Si C porous ceramics,and the correlation between the conductivity and the dielectric constant of the composites was analyzed.When the thickness of the sample was 2.5mm,SiC/Al₂O₃composites and SiC/MoSi₂ composite materials shows more obvious absorbing effect as compared with SiC porous ceramics.It should be noted that the reflection coefficient of SiC/MoSi₂ composite materials was reached to 12.69d B at 9.9 GHz.As the result,SiC/MoSi₂ composite could be a promising structural function of absorbing material.