Preparation And Microwave Absorbing Properties Of SiC_nw 3D Network Reinforced Aluminum Phosphate Composites

With the development of radar detection technology,the stealth performance of aircraft has become a key factor affecting its security,battlefield survival and penetration ability.In addition,with the increase of flight speed,the aerodynamic heating effect of aircraft is intensified.Radar wave absorbing materials not only pursue but also light,thin,wide and strong,but also have the characteristics of high temperature resistance and oxidation resistance.Carbon based absorbing materials and magnetic loss absorbing materials can not meet the application requirements.Silicon carbide nanowires(SiC_nw)are considered to be the most promising high temperature absorbing materials due to their excellent mechanical,oxidation resistance and thermal stability.However,as a semiconductor material,SiC_nwhas a single loss mechanism,low conductivity and insufficient dielectric loss,so its microwave absorption performance can not meet the application requirements.In view of the above problems,this paper proposes to use SiC_nwto lap into a three-dimensional network,enhance its conductivity loss,and further optimize its microwave absorption performance.The above-mentioned SiC_nwis used as a microwave absorber and reinforcement to prepare composite materials with high temperature resistance,wave absorption and load-bearing functions,which has important theoretical and application value.In this paper,we use iron as catalyst and carbon fiber as reaction substrate,SiC nanowires were synthesized by the reaction of SiO and carbon fiber,and the network was formed spontaneously.The effects of temperature,holding time and amount of catalyst on SiC_nwwere studied.The results show that stacking faults in SiC nanowires are closely related to the content of 2H-SiC.Stacking faults are closely related to the amount of catalyst and holding time.The stacking fault density decreases with the increase of catalyst content and holding time.The amount of SiC_nwis affected by reaction temperature,catalyst content and holding time.The amount of SiC_nwincreased with the increase of holding time,catalyst content and temperature.The amount of catalyst is an important factor affecting the morphology of SiC_nw.When the amount of catalyst is less than 1000ppm/L,the aspect ratio of SiC_nwis higher.When the amount of catalyst is more than 1000ppm/L,the growth of SiC_nwis inhibited,the aspect ratio is reduced and clusters are formed.The holding time has a great influence on the length and bending degree of SiC_nw.With the increase of holding time,the length of SiC_nwincreases and the bending degree of SiC_nwincreases.SiC nanowire network was used as reinforcing phase and absorbing agent,and aluminum phosphate was used as matrix to prepare absorbing and bearing composites.The results show that the preparation process of SiC_nwhas a great influence on the microwave absorbing properties.With the increase of reaction temperature,the amount of SiC_nwincreases,the dissipation ability of electromagnetic wave increases,but the impedance matching performance decreases.With the increase of SiC_nwholding time,the cole Cole image gradually changes from semicircle to linear shape,which indicates that longer SiC_nwis easy to form conductive network,and the loss mechanism gradually turns to conductive loss.The three-dimensional network of SiC_nwwas prepared as follows:holding at 1400℃for 2h,catalyst 100ppm/L.When the thickness of the SiC_nw/Al PO4 composite is 3.4mm,the minimum reflectivity of the material reaches-46.4d B（17.12GHz）,and the effective absorption band reaches 7.84GHz（7.28GHz to9.6GHz and 12.48GHz to 18GHz）.