Preparation Of Carbon-Based Wave-Absorbing Materials By Solid-Phase Cracking And Its Performance Study

The 5G era has led to the booming development of electronic information technology,especially communication and detection technology.It has greatly promoted the wide application of various electronic devices in many fields,but also led to the intensification of electromagnetic pollution.In order to protect the human body and some delicate equipment from the damage of electromagnetic pollution,researchers have invested a lot of efforts in the direction of electromagnetic wave absorbing materials.Traditional magnetic metal powder and other electromagnetic wave absorbing materials can no longer meet the requirements of today’s use environment due to various limitations,and the direction of research has now shifted to carbon-based materials.Carbon-based materials offer great advantages in terms of filling density,dielectric constant,flexibility and corrosion endurance.Sometimes a single carbon material can cause its conductivity to be too high,making impedance matching difficult.The solution is to introduce some other materials that reduce the overall electrical conductivity of the material or introduce other absorption mechanisms,thus making the material have a better effective absorption bandwidth.In thesis,copper phthalocyanine is used as the subject material to produce carbon based absorbing materials with excellent performance by various auxiliary preparation methods with solid phase cracking method,and the research is divided into the following three parts:(1)Carbon nanosheets with intercalated copper particles were prepared by a onestep solid-phase cleavage method using copper phthalocyanine as the precursor.Copper phthalocyanine is cleaved into carbon nanosheet layers at high temperature and can regulate the dielectric by its own copper element without adding other low dielectric materials,providing a possibility for easy production on an industrial scale.The results show that the samples obtained at a sintering temperature of 900 °C have a maximum absorption bandwidth of 4.48 GHz(12.08-16.56 GHz)at a matched thickness of 1.7mm.(2)Using KCl as the salt template and copper phthalocyanine as the precursor,the copper phthalocyanine was uniformly dispersed on the salt particles by the antisolvent method,so that it was cracked by heat to form a carbon film with thinner thickness and cavity structure.The carbon film with a large two-dimensional layer structure allows a better formation of the conductive network,and the molten KCl also prevents the agglomeration of copper particles,which allows the material to have a good performance of wave absorption at a very low filling density.The results show that when the sintering temperature is 900 °C and the ratio of KCl to copper phthalocyanine is 100:1,the obtained samples have a maximum absorption bandwidth of 6.88 GHz(11.12-18 GHz)at a matched thickness of 2.1 mm,covering the entire Ku band.(3)Carbon materials with a composite structure of three-dimensional honeycomb and carbon nanotubes were obtained by using sodium citrate and copper phthalocyanine as a dual carbon source.The addition of copper phthalocyanine adjusts the overall impedance matching of the composite material and enriches the electromagnetic wave loss mechanism,effectively enhancing the wave absorption performance The results show that when the sintering temperature is 800 °C and the ratio of sodium citrate to copper phthalocyanine addition is 20:1,the produced samples have a maximum absorption bandwidth of 5.76 GHz(11.92-17.68 GHz)at a compression ring thickness of1.7 mm.