Design And Preparation Of High Temperature Absorbing Materials Based On Nichrome Film

With the development of modern military technology,stealth technology is more and more used in various complex environments.In recent years,the rapid development of ultra-high speed weapon equipment has put forward higher and higher requirements on the temperature resistance of surface absorbing materials.As a representative high-temperature resistant alloy,nichrome is widely used in various high temperature environments,but rarely used in high temperature absorbing materials.Therefore,this paper focuses on the study of nichrome film prepared by magnetron sputtering.Nichrome film were applied to a variety of structures of microwave absorber,as the main absorbing agent in the form of doping,res istance film and res istance patch,and obtained excellent absorbing performance.The absorbing performance and working temperature of nichrome film applied to structural wave absorber are improved step by step,and the practical application of nichrome film in high temperature wave absorbing field is realized.In view of the current situation that high temperature absorbing materials mainly have dielectric loss and conductance loss,and magnetic loss is difficult to play a role,two new design methods of non-magnetic/weak magnetic absorbing materials are proposed.Dallenbach absorbing body of the homogeneous medium composition,the non-magnetic/the impedance matching conditions of weak magnetic material reduced to simple mathematical relationship of electromagnetic parameters,calculation of thickness approximation of impedance matching method is proposed,for the future of the absorbing material performance study provides a convenient,simplify solving methods can provide reference for similar studies in the future.At the same time,the expression of quarter wavelength with error is discussed.For the Jaumann structure absorber,it is noted that the dielectric layer can play a role of heat insulation protection to the resistance layer material.Taking a simplified Jaumann structure as the analys is object,the frequency derivative function and monotonicity of the transmission line expression of its reflectivity are analyzed in detail.The mathematical relationship between the design parameters and the absorbing performance of the simplified Jaumann structure is determined,and the complete design rules of the absorbing structure are obtained,which has wide applicability.The method of analyzing the reflectivity curves of Jaumann structures by using the derivative function and monotonicity provides a new idea for the analysis and design of structural absorbers.Nichrome coating was prepared by magnetron sputtering using quartz fiber cloth and quartz sheet as the substrate.The structural absorber with nichrome film as the main absorbing agent has a minimum reflectivity of-55 d B,a maximum absorption bandwidth of 6.0～18.0GHz lower than-10 d B,a minimum thickness of 3 mm,and a maximum operating temperature of 600 ℃.In this paper,nichrome film was successfully applied to the preparation of structural wave absorbers and its application in high temperature wave absorption was explored.As a functional component of the absorber,nichrome film respectively forms Dallenbach absorber,Salisbury-like absorber,simplified Jaumann structure absorber and circuit analog absorber in the form of doping,resistance film and resistance patch,which basically covers the most widely used absorber types.There are advantages and disadvantages in "thin","light","strong" and "wide".Through progressive research,the temperature res istance of the absorber based on nichrome film is gradually improved,and the working temperature is increased from 300～350 ℃ to 400～600 ℃,which provides a new direction for the research of high temperature absorbing materials.