基于煤矸石的新型微波吸收材料设计、合成与性能研究

For the demand of lightweight magnetic-loss absorbents, the ceramic-based microwave absorbing materials, metal/carbon/ceramic ternary composites will be prepared using the industry solid waste, coal gangue as raw material in this study. First, the lightweight and porous proppants were synthesized by the coal gangue combined with pore-forming agent. The ceramic-based absorbents could be prepared using coal gangue-based proppants as carrier to load different precursor solution through capillary action as well as the subsequent carbothermal reduction at different annealing temperatures under an inert atmosphere. And the magnetic components iron, cobalt, nickel, etc. uniformly loaded ceramic-based composites were prepared in a controllable way by optimizing parameters, including synthetic process, the liquid phase synthesis method and carbothermal reduction schedule. Moreover, microwave absorption and the corresponding loss mechanism were investigated by studying the electromagnetic characteristics of ceramic-based composites, which could conversely adjust the phase composition, microstructure and properties of the absorbents. It was found that the prepared metal/carbon/ceramic ternary composites possessed the advantages of wide raw material sources, low cost and simple preparation process, exhibiting excellent microwave absorption. In addition, the issues of high density for magnetic-loss absorbents as well as high efficiently utilizing of coal gangue were resolved simultaneously. All of which provided the experimental and theoretical basis for recycling coal gangue to prepare the novel ceramic-based absorbents.

针对磁损耗吸波材料轻质化的发展要求，本研究拟利用固废煤矸石制备金属/碳/陶瓷三元复合吸波材料。通过引入造孔剂，以煤矸石为原料合成轻质、多孔结构的煤矸石基陶粒，然后借助毛细作用将不同体系的前驱体溶液引入到煤矸石陶粒内部，经惰性气氛下不同温度焙烧即可获得陶瓷复合吸波材料。围绕合成工艺、液相制备方法及碳热还原反应制度等参数进行优化设计，从而实现Fe、Co、Ni等不同磁性组分均匀负载的陶瓷复合吸波材料可控合成，并研究复合材料的电磁特性，阐明复合材料的微波吸收性能及损耗机理，达到对复合材料物相组成、微观结构和吸波性能的较精确调控。最终制得的金属/碳/陶瓷三元复合吸波材料吸波性能良好，而且原料来源广泛，成本低，所涉及的制备工艺简单。该研究可以有效解决磁损耗吸波材料比重大的问题，同时也实现了煤矸石的高效回收利用，为综合利用煤矸石制备新型陶瓷基复合吸波材料提供实验依据和理论基础。

针对磁损耗吸波材料轻质化的发展要求，本研究利用固废煤矸石制备金属/碳/陶瓷三元复合吸波材料。首先通过引入造孔剂，以煤矸石为原料合成轻质、多孔结构的煤矸石载体，然后借助毛细作用将不同体系的前驱体溶液（Fe3+、Co2+、Ni2+）引入到煤矸石载体内部，经惰性气氛下不同温度（600-900℃）焙烧2小时即可获得负载Fe、Co、Ni的陶瓷复合吸波材料。基于上述研究思路，为了实现磁性组分在基体中的更均匀分散以及精准定量分析，对合成工艺方法进行了优化设计，采用了一步法直接将煤矸石粉体分散于一定浓度的前驱体溶液中，经过后续的旋转蒸发和原位碳热还原即可得到复合微波吸收材料。两种合成方法得到的复合材料吸波性能较好，在涂层厚度为1.5-2.5 mm时，对应的最低微波反射损耗值为–25-–45 dB，有效吸收带宽可达3.5-4.5 GHz，通过探究微波吸收机理，可知该复合材料主要以介电损耗为主。另外，通过改变前物体溶液浓度可以直接调控磁性组分在复合材料中的负载量，进而起到调节阻抗匹配的作用，最终实现了优异的吸波性能。值得一提的是，将该研究思路方法尝试应用于固废粉煤灰和煤气化残渣后，经过调整工艺参数成功制备得到了粉煤灰基与碳基复合吸波材料，吸波性能与同类型的材料相比，显示出涂层厚度薄及粉体密度小的优点。该研究不仅有效解决了磁损耗吸波材料比重大的问题，同时也实现了煤基固废煤矸石、粉煤灰和煤气化残渣的有效回收利用，兼顾环境效益、经济效益和社会效益，而且为综合利用煤矸石、粉煤灰和煤气化残渣制备新型复合吸波材料提供了实验依据和理论基础。研究结果也为煤基固废的资源化利用开辟了新途径，助力双碳目标的实现。