Porous Dielectric Material Thermal Behavior Research

Space wave-transmitting material requirements that it can be through by electromagnetic wave in the extreme bad environment, and we hope that it could afford to meet the requirements of the structure and temperature. Wave-transmitting material have been widely used in the rocket, the spacecraft, weapons, and aerospace craft, it is a kind of low dielectric constant and low loss dielectric material. Due to the influence of the temperature and air pressure,we also require electrical structure properties of small temperature coefficient and even the same. Silicon oxide has low dielectric constant and dielectric loss, which makes it fully used in space, but due to their poor mechanical properties and corrosion resistance,it can not meet the requirements of aerospace science and technology rapid development. Silicon nitride has good corrosion resistance, high mechanical strength and dielectric properties of satisfaction,and we are trying to replace silicon oxide with system of silicon nitride material. Under the condition of satisfy the corresponding mechanical properties, we try to adopt porous structure to further lower dielectric constant and dielectric properties of silicon nitride materials. The research content of this paper include:(1)Combining the basic theory of dielectric physics and so on, the silicon nitride,silicon dioxide polarization factors are fully analyzed, from the micro perspective of established the silicon oxide, silicon nitride materials such as dielectric constant,dielectric loss and dielectric constant temperature coefficient under high temperature and high frequency mathematical model. We put the calculation results with the experimental results of fitting, and quantitative analysis of the value of various variables on the dielectric properties of the influence of sensitivity.(2)Through the analysis of the two phase composite of different models, we established a porous silicon oxide and silicon nitride materials, the mathematical model to study the factors which may have an effect on dielectric properties, such as porosity,frequency and the impurity ions, etc., and the quantitative calculation of the degree of their influence on dielectric properties. The analysis are discussed in detail, alkali metals and alkaline earth metal ions, greatly improve the cause of the dielectric loss,and through the model validation is derived.(3)We study the porous silica ceramic doped high temperature performance ofmicrowave, the analysis of silica mixed with titanium dioxide, zirconium oxide, silicon carbide, mullite porous composite materials composed of dielectric properties. We compare the corresponding dielectric properties of composite materials, get the best performance of doping substances, and the corresponding mechanism analysis is given.(4)We research on porous silicon nitride ceramics doped with high temperature performance of microwave, porous silicon nitride material mixed with a certain quality score alumina, yttrium oxide respectively, and analyzed the influence of different doping on the dielectric properties.(5)In view of the polarization mechanism of material, combining the theory of interface states, defect and relevant theory, we analyze the dielectric loss in the composite material of our system of mechanism.(6)Combined with the simulation results and the related dielectric performance in front of the test results, contact material dielectric mechanism analysis, we give corresponding interpretation and validation, and found in the new phase of the test free silicon and silicon oxide of nitrogen analysis.