回收利用煤矸石低成本制备Ni/C/CG复合型吸波材料

Low-cost preparation of Ni/C/CG composites for microwave absorption by recycling coal gangue

采用煤矸石(CG)作含碳载体、淀粉作补充C源、硝酸镍作Ni源,借助液相浸渍结合碳热还原工艺制备Ni/C/CG复合型微波吸收材料;研究碳热还原温度对材料组成、微观结构与性能的影响。结果表明,碳热还原温度会影响碳与Ni的结晶状态及Ni微粒大小,进而对材料的电磁性能特别是介电性能产生显著影响。得益于良好的阻抗匹配特性与强的微波衰减能力,在600−800℃较宽的温度范围内制备得到的Ni/C/CG复合材料均显示出优良的微波吸收性能。其中,800℃热处理样品的最低反射损耗可达−20.9 dB,相应的有效带宽为3.8 GHz(测试涂层厚度为2 mm)。介电损耗是主要的微波吸收机制,主要源于材料中石墨化的碳与Ni微粒所引起的漏导损耗及各组元间界面带来的界面极化损耗。

With coal gangue(CG)as the carbon-containing carrier,starch as supplementary C source and nickel nitrate as Ni source,Ni/C/CG composite microwave absorbing materials were prepared by a solution impregnation and then a carbothermal reduction process.The influence of the carbothermal reduction temperature on the composition,microstructure and performance of materials was carefully studied.It was found that,the carbothermal reduction temperature had a great effect on the crystalline state of carbon and Ni,as well as the size of Ni particles,further greatly affected the electromagnetic properties,especially the dielectric properties of the materials.Due to the combination of good impedance match and strong microwave attenuation ability,the Ni/C/CG composites prepared under a wide temperature range of 600−800℃all displayed excellent microwave absorption performance.For the sample heat-treated at 800℃,the minimum reflection loss could reach−20.9 dB at 12.9 GHz and the corresponding effective absorption band was 3.7 GHz with a coating thickness of only 2 mm.In addition,the dielectric loss was the dominant microwave absorption mechanism,which mainly originated from the conductive loss caused by the graphite carbon and Ni particles,and the interfacial polarization loss due to the existence of interface between Ni,C and CG.