| With the popularization of miniaturized and intelligent electronic equipment,the problem of electromagnetic radiation and electromagnetic pollution is becoming increasingly serious,which not only interferes with electronic equipment,but also endangers human health.Therefore,the development of materials with high electromagnetic shielding performance is of great practical significance.In this thesis,electrodeposition technology is used to modify the surface of carbon fibers with light weight and high strength,and their electromagnetic shielding performance is explored.The main research contents are as follows:(1)A small carbon fiber continuous plating device was prepared.Based on the existing carbon fiber continuous plating device,this new device adds a "T" anode holder that can be moved back and forth,a double pure copper conductive roller for carbon fiber S-winding,and a guide roller that keeps the carbon fiber parallel to the anode.It effectively solves the "black heart" phenomenon of carbon fiber during electroplating.In addition,the influence of electroplating process parameters on coating quality is also studied,so as to determine the optimal electroplating process parameters of carbon fiber.(2)A composite film with adjustable reflectivity was prepared.Nickel-plated carbon fiber fabric was prepared by shearing and filtering nickel-plated carbon fiber,in which nickelplated carbon fiber was obtained by electroplating.By encapsulating the fabric with polyimide resin,a nickel-plated carbon fiber-based film was finally prepared.In addition,the differences between conventional nickel carbon fiber-based films and nano-cone nickel carbon fiber-based films are also compared in terms of electromagnetic shielding properties and mechanical properties.The results show that: When the amount of nickel-plated carbon fiber is 0.1 g,the reflectivity of conventional nickel-carbon fiber film is about 0.31,and the shielding efficiency is about 24 dB.The reflectivity of the nano-cone nickel carbon fiber film is about 0.47,and the shielding efficiency is about 40 dB.It is explained that when the amount of addition is low,absorption is the main loss mechanism of both composite films.When the amount of nano-cone nickel carbon fiber is 0.3 g,the electromagnetic shielding efficiency of nano-cone nickel carbon fiber based film in the X-band reaches 71 dB,and the thickness is only 1.2 mm.It is significantly better than the electromagnetic shielding efficiency of conventional nickel carbon fiber film(57 dB).And at this time,both composite films have reflection as the main loss mechanism.Moreover,the tensile strength of nano-cone nickel carbon fiber-based film is 22.4 MPa,which is significantly better than that of conventional nickel carbon fiber based film(18.3 MPa).(3)The possibility and feasibility of chopped nickel-plated carbon fiber as a coated absorber were discussed,and the differences between the two chopped nickel-plated carbon fiber were compared in terms of physical properties and wave absorption properties.The results show that for nano-cone nickel carbon fiber powder,the absorption strength reaches-39.2 dB when the matching thickness is 1.5 mm,and the absorption bandwidth reaches 3.1GHz when the matching thickness is 5 mm,which shows significantly better than the absorption performance of conventional nickel carbon fiber powder.However,compared to other absorbing materials,the absorption range and absorption strength of chopped nickelplated carbon fiber are still low.It is not suitable as a coating absorbent.(4)An electromagnetic shielding film was prepared based on copper-plated carbon fiber.When the amount of copper-plated carbon fiber reaches 0.3 g,the shielding loss value reaches85 dB,showing excellent electromagnetic shielding characteristics.In addition,due to the high conductivity and diamagnetism of copper,when the amount of copper-plated carbon fiber is 0.1 g,the reflectivity of the composite is still higher than 90%. |
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