Preparation Of Phenolic Resin Based Carbon Foam Composites And Its Electromagnetic Shielding Properties

With the development of science and technology,communications,phone,television,computer and other electromagnetic radiation system were widely used,Electromagnetic pollution has brought great challenges to a variety of electronic systems applications and design,and also caused more and more disasters and accidents to the human.The development of efficient composite electromagnetic shielding materials has become an important topic in the field of materials science and electromagnetic compatibility,which is an important method to isolate electromagnetic pollution,solve electromagnetic compatibility problems and reduce disaster and accidents.The surface of the electromagnetic shielding material usually has continuous conductivity,and electromagnetic waves can absorb and reflect inside the material.Carbon foam is a new material composed of amorphous carbon and graphite with high porosity,high specific surface area,high conductivity,low density,etc.The carbon foam has attracted a lot of attention due to its excellent thermal stability,the lower density,low expansion rate and them has been widely used,such as thermal management materials,battery electrodes,super capacitors,catalyst carriers,technology separation,aerospace and other fields.Phenolic carbon foam has the characteristics of wide raw material source and simple manufacturing process,but the electromagnetic shielding effect of the traditional phenolic resin-based carbon foam has defects.However,the foam structure of the traditional phenolic resin-based carbon foam is not uniform,the electrical conductivity is not good,and the compression performance is also flawed,which seriously limits its application in the industrial field.At present,there are still some deficiencies in the application of new materials in the modification of carbon foam electromagnetic shielding effectiveness.As a novel three-dimensional material,the graphene hybrid material can fully exert the excellent characteristics of graphene and another material,and its unique three-dimensional structure can improve the cell structure of the carbon foam matrix,and its good conductivity is improved.The material's electrical conductivity and electromagnetic shielding properties are used.Therefore,the electromagnetic shielding effectiveness of the carbon foam modified by graphene hybrid materials is proposed in this paper,and a carbon fiber-hybrid material modified carbon foam is prepared,and the electromagnetic shielding effectiveness and compression performance of the carbon foam are improved together.In this paper,we modified the phenolic carbon foam by three methods:First,GO/SiO₂hybrid material modified carbon foam electromagnetic shielding effectiveness.The GO/SiO₂hybrid materials with particle sizes of 80nm,170nm and 250nm were prepared by the control of the reaction time.The GO/SiO₂ hybrid materials modified carbon foam with different particle diameters and different contents were prepared.Matrix structure,mechanical properties and electromagnetic shielding performance in the range of 8-12 GHz were studied.The experimental results show that the GO/SiO₂ hybrid material as a heterogeneous nucleating agent can obviously improve the structure,the electromagnetic shielding efficiency and compression performance of carbon foam.When the GO/SiO₂ hybrid material content is 1wt%,the carbon foam showed a small mean cell size and uniform structure.When the particle size of the GO/SiO₂material is 80nm and the content is 1.5wt%,the hybrid material form a good conductive network in the matrix,which improved the electrical conductivity of the material.The electromagnetic shielding effect of the material is 50 dB,which has achieved a higher using standard.Second,the GO/Fe₃O₄ hybrid material was prepared by coprecipitation method to improve the electromagnetic shielding effectiveness of carbon foams.When the content of GO/Fe₃O₄ is1wt%,the carbon foam showed the best cell structure and mechanical properties.The GO/Fe₃O₄hybrid material can improve the electrical conductivity of the material,it can improve the permeability of the material and electromagnetic shielding efficiency of the material effectively.When the content of GO/Fe₃O₄ is 1.5wt%,the electromagnetic shielding effect of carbon foam showed the highest 63.5dB.And the compressive strength and modulus showed 13.8MPa and0.98GPaThird,GO/Fe₃O₄ and carbon fiber co-modified carbon foam,when the GO/Fe₃O₄ content of1wt%,carbon fiber content of 1wt%,carbon foam matrix showed a more uniform cell structure.Shielding effectiveness and mechanical properties are both excellent,it can be used in the occasion with high requirement of electromagnetic shielding effectiveness and mechanical properties.