Influence Of Micro Structures Of Carbon Fiber Reinforce Ceramics Composites On Water Adsorption

The military power represented by the United States and Russia strive to develop hypersonic flight technology.They are constantly start research projects of hypersonic flight technology at different levels.During the high speed continuous flight,airflow on the surface of aircraft is blocked due to friction and other reasons,kinetic energy is transformed into heat energy,which generates aerodynamic heating,the surface temperature of aircraft is increased.At the same time,the transpiration cooling technology of thermal protection materials have draw more and more attentions.Different fiber endings will be explored on the C/SiC surfaces,which will exert influence on the cooling system efficiency.We aim to investigate the influence of C/SiC surface micro-structure on surface wettability,the main conslusions are as follows:Firstly,the typical flowing channels at C/SiC subsurface were discussed,the water droplet adsorption models were established based on washburn equation.Two models corresponds to circle fiber ending C/SiC surface and pillar fiber ending C/SiC surface respectively.The relationship between water droplet volume and water adsorption time was investigated on a single sample first.Considering the stochastic nature of the flowing channels of C/SiC.The water adsorption experiments were repeated 2000 time.The results showed that the water adsorption time on pillar fiber ending C/SiC surface lag behind the water adsorption time on circle fiber ending C/SiC surface.Based on the time-lag effects.We proposed a potential method about laser ablated C/SiC surface micro-structure used for reducing the time-lag effects.Secondly,to fabricate the wetting controllable C/SiC surface,we designed three typical surfaces.Considering the surface characters will directly influence the surface performances,four parameters(Sz?Sku?Ssk?Sq)were discussed.The Sz value was selected to be the basic parameter in the following model works.Thirdly,the potential chemical changing on C/SiC surface were investigated.The water droplet adsorption model on C/SiC surface with micro-structure was established,the relationship between water droplet adsorption time and laser scanning time was discussed,the relationship between water droplet adsorption time and micro structure was also discussed.The results showed that the micro structure can actively control the water droplet adsorption time on C/SiC surface.The conclusions can provide important references for improving transpiration cooling system efficiency.