Study On Technology For Compositing SiC To Resin Carbon In-situ And Microwave Absorption Properties Of The Complex

A novel composite as C/SiO2/SiC was prepared through sol-gel and carbon thermalreduction, with phenolic resin as carbon source and ethyl silicate as silicon source.The influence of ratio of precursors, carbonization temperature and reaction time onon the characteristics of the prepared sample such as crystal structure, morphologyand electromagnetic parameters etc were systemly investigated, and optimumtechnological parameters were built to prepare C/SiO2/SiC composite with highperformance for microwave absorbing. It was found that the homogeneous gel,temperature of thermal reduction, and the amount of TEOS in sol-gel reaction haveclose relationship with micro structure of the prepared sample, which effect on theproperties of dielectric constant, conductivity, and electromagnetic parameters.High temperature for carbon thermal reduction can benefit the formation and thecrystallinity of SiC accompanying with whisker produced; and enough time of heatpreservation for the prepared sample can also promote the crystallization andgeneration of SiC. Taking ferric chloride as catalyst of carbon thermal reductionreaction, C/SiC_wcomplex with a large number of SiC whisker can be generated atrather low temperature. After investigating the effect of catalyst, reaction temperatureand heat preservation on component, crystal structure, morphology andelectromagnetic parameters of C/SiC_wcomplex, We found that the iron catalyst canreduce the temperature for forming SiC whisker, of which the microwave absorbingperformance was improved with a high theory reflection loss and the wide bandwidthunder5dB, as thickness of the prepared sample increasing, maximum theoreticalreflection loss peak moves towards low frequency.Combing sol-gel with vacuum impregnation method, the sol precursor wassuccessfully impregnated into carbon fiber fabric body to form gelation, and C/Ccomposite material with SiC formed in-situ was prepared after its carbon thermalreduction, which has good microwave absorbing properties. The effect of precursorratio on the micro structure and properties of the prepared sample were investigated,and C/C composites with SiC composited that has the best microwave absorptionperformance was found. Results show that SiC crystalline generated by different TEOS ratio in preparation of C/C composites is different, having different microwaveabsorption performance. The biggest real reflectivity of SiC doped C/C composites isabout-19.3dB, which has potential to work in high temperature for microwaveabsorbing.