The Design And Synthesis Of Co/C Composite Materials And Its Electromagnetic Wave Absorbing Property

With rapid the development of electronic technology, the electromagnetic wave absorbing materials have attracted more and more attention for the reason of the increasing problem of electromagnetic interference. Metal Co has been more widely studied in the field of electromagnetic wave absorption. Hierarchical structural nanomaterials had multi-level, multi-dimensional, multi-component coupling and synergies,which could improce the properties of materials, so researchers began to study Co with hierarchical structure, and found that its microwave absorbing properties was superior to disordered Co. According to reports,the absorbing performance of Co was improved significantly after combining with C with dielectric properties. However few researchers study the hierarchical structure of Co/C composite materials. Therefore, this paper aims to explore how to design and synthesis hierarchical structural Co/C composite material and improve its electromagnetic wave absorption performance.Two types of Co/C composite materials were successfully prepared through the synthetic route design in this paper. In firsr route, Co3O4/phenolic resin composite material were synthesized through in situ polymerization, then putting it into tube furnace for calcining in mixed atmosphere of hydrogen and nitrogen at different temperatures to obtain a carbonized core-shell structure Co/C composite material. In second route, Glucose was introduced into the synthetic process of the precursor-Co-glycerate, then putting it into tube furnace for calcining in mixed atmosphere of hydrogen and nitrogen at different temperatures to obtain carbonized Co/C composite material. Core-shell Co/C composite material was synthesized successfully, and the test results showed that its property of microwave absorbing was better than Co, and the carbonization temperature and the thickness of carbon shell could affect the absorbing properties of the materials. Co/C-650 composite material displayed optimal microwave absorbing performance in all samples. This result benefited from the interaction of Co core and carbon shell, which can better realize impedance matching at 650 ℃ carbonization temperature, making electromagnetic waves into composite microspheres and in which conducting multiple reflections to achieve a higher absorption. The maximum reflection loss of S2-650(resorcinol/methanol=0.1 g/0.14 m L) reaches-30.53 d B at 8.5 GHz,and effective bandwidth was 3 GHz. This paper designed second route to synthesise Hierarchical structural Co/C composite microspheres with Uniform morphology and size. The maximum reflection loss value of Co reaches-7.03 dB at 17 GHz The maximum reflection loss value of Co/C-500 reaches-15.92 dB at 14 GHz and bandwidth reached 6 GHz. The maximum reflection loss value of Co/C-600 as well as reached-15.88 d B at 10 GHz and bandwidth reached 4 GHz.