Study On Porous Cement-based Electromagnetic Shielding Composite Materials Of Graphite, Carbon Fibe

Along with the TV, computer, mobile phones and other electronic and electricalequipment widely used, electromagnetic radiation has spread to every corner of ourlife. It improved the quality of our life, but brought serious harm to our life andproduction, such as interference of the normal operation of the electrical and electronicequipment, impacts on health, etc. Therefore, on the electromagnetic shielding, manyresearchers at home and abroad made a lot of research.Cement have advantages with a sufficient resources, stable performance, strongapplicability, low price. It contains a variety of metal oxide which has a certain loss tothe electromagnetic wave. When in the cement-based adding electromagnetic lossymedium and forming porous structure can further improve shielding effectiveness ofthe cement-based composite materials. In the experiments, we prepared two kinds ofcomposite materials, the cement-based mixed foam agent and cement-based mixedexpanded polystyrene, studied on their electromagnetic shielding effectiveness,conductivity, cement mortar consistency and mechanical strength.In the composite materials of cement-based mixed foam agent study, the effectof the additions of carbon fibers and graphite powder on conductivity and shieldingeffectiveness was mainly discussed. In the conductivity aspects, the more the additionof carbon fibers, the smaller the resistance. In the specimens which was mixedgraphite powder and carbon fibes together, the increase of the addition of carbonfibers is helpful to reduce resistivity. In the shielding effectiveness aspects，thegreater the amount of carbon fibers or graphite powder, the better shieldingeffectiveness of the samples are. When carbon fibres and graphite powder mixedtogether, the perfect content of graphite powder relate with the addition of carbonfibers and the optimal content of carbon fibers was2%for the best shieldingeffectiveness.In the composite materials of expanded polystyrene cement-base study, discussed the mixed quantity of the EPS particles, expanded graphite and carbon fibers on theinfluence of samples’ shielding effectiveness and mechanical strength. In theshielding effectiveness aspects, the samples’ shielding effectiveness increases with thepolystyrene particles admixture’s decrease. In the samples only mixed expandedgraphite or carbon fiber, the increase of the admixture can improve shieldingeffectiveness. The samples mixed expanded graphite and carbon fibers together havebetter shielding effectiveness than the samples only mixed expanded graphite orcarbon fibers. In the samples mixed expanded graphite and carbon fibers, With theincrease of carbon fibers dosage, the expanded graphite admixture have more obviousimpact on sample’s shielding effectiveness, and the more the carbon fibers areadded, the better shielding effectiveness is. In the mechanical strength aspects, themore the sample mixed only EPS particles, the smaller flexural and compressivestrength is. In the samples only mixed carbon fiber, the smaller flexural andcompressive strength of the sample mixed2%is the best. In the samples only mixedexpanded graphite, with the increase of the expanded graphite admixture, the trends offlexural and compressive strength are growing.