Study On Preparation And Electromagnetic Shielding Effectiveness Of Bamboo Charcoal Supporting Copper

In this paper, bamboo charcoal was used as carrier, Cu and bamboo charcoal formed athree-dimensional network structure of carbon gold with bamboo charcoal pore as template.In this process, we made the best of the adsorption properties of bamboo charcoal, theresolvability of Cu（NO₃）₂and the displacement reaction between C and CuO. Thethree-dimensional network structure can enhance the electromagnetic shieldingeffectiveness of bamboo charcoal.Single factor test was used to investgate the effect of baking temperature and holdingtime on the pore structure of bamboo charcoal. Both single factor test and orthogonalexperiment were used to investgate the effect of baking temperature, pH, adsorption time,addition of bamboo charcoal, adsorption temperatures and the concentration of Cu（NO₃）₂on the adsorption of Cu（NO₃）₂. Atomic absorption spectrophotometer and automaticspecific surface area were employed to characterize the carbon materials. The resultsshowed that the optimal preparation parameters were as follows: baking temperature700℃, pH6.0, adsorption time80min, addition0.05g/mL, adsorption temperatures20℃and the concentration of5mol/L. The order of factors interaction strength follows from thestrongest to the weakest is baking temperature, dsorption temperatures, adsorption time,addition of bamboo charcoal, the concentration of Cu（NO₃）₂and pH.XRD was employed to investgate transition process of Cu（NO₃）₂. The results showedthat bamboo charcoal was high pure amorphous carbon. It began to the reaction ofdecomposition reaction（2Cu（NO₃）₂（s）â†'2CuO（s）+4NO2（g）+O2（g）） at170℃. When theholding time is30min, the reaction is completed. When the holding time is15min at hightemperature, the displacement reaction（C+2CuO=2Cu+CO2↑） began. And we can foundCu in the bamboo charcoal. But when the holding time is50min, this reaction wasn’tcompleted. This may be realeted to the specific surface and pore size distribution ofbamboo charcoal.Automatic specific surface area, SEM, wheatstone bridge method and spectrum analyzerwere employed to characterize the property of bamboo charcoal. The results showed thatthe volume resistivity of declined sharply with the rise of the carbonization temperature.When the baking temperature is700℃, the volume resistivity is27.49·cm. Then thevolume resistivity began to decline slowly with the rise of the carbonization temperature.After the adsorption of Cu（NO₃）₂, the pore of bamboo charcoal were blocked completelyor partially and the specific surface area and pore volume decreased. After the high temperature treatment of bamboo charcoal, Cu（NO₃）₂had the decomposition reaction, Cand CuO had the replacement reaction and the specific surface area of bamboo charcoalbegin to become bigger. Cu and bamboo charcoal formed a three-dimensional networkstructure of carbon gold with bamboo charcoal pore as template. This made the volumeresistivity reduced with the number of class. When the baking temperature is700℃, theelectromagnetic shielding efficiency of bamboo charcoal was between3⁶db. With theincrease of Cu element content, the electromagnetic shielding efficiency increasedsignificantly, and it can achieved24db when the content of Cu element content is152mg/g.