Preparation And Performance Evolution Of Fluoro-silicon Superhydrophobic Coating Applied On GFRP Surface

Due to the advantages of low dielectric constant,good wave transparency and light weight,glass fiber reinforced polymer composites(GFRP)are often used in fabricatiung radomes for ground radars.However,radar radomes are always affected by environmental factors such as light,rain,and temperature changes,which will accelerate the aging process of GFRP,critically shorten its service time.Meanwhile,the raindrop form a layer of thin water film during the rainfall process.The water film will reduce the transmission accuracy of the antenna,increase its transmission loss,and reduce the receiving efficiency of the radar antenna significantly.This research aims at coating material applied on the surface of GFRP substrate.Coating material was designed to be capable of large-scale production,use simple production equipment,and can meet the low-temperature curing process of fiber-reinforced composite materials without affecting the dielectric properties of the GFRP substrate.Finally,vinyl-based PTFE was used as coating resin,isocyanate trimer was used as curing agent,nano-silica was used as filler,and butyl acetate was used as solvent,fluoro-silicon composite coating was prepared by blending method.In this research,the effects of the amount of curing agent and nano-silica on coating properties were investigated.The system of coating material ratio was optimized.Finally,a superhydrophobic coating was successfully prepared on the surface of the GFRP substrate.When the amount of curing agent is 20wt% and nano-silica is 30wt%,the water contact angle of the fluoro-silicon composite coating reaches 158.67°,which is superhydrophobic.Scanning electron microscope and atomic force microscope results shows that the addition of nano-particles changes the surface morphology of the composite coating,results in uniform and dense nano-scale protrusions on the surface,and greatly increases the surface roughness.By analyzing the chemical structure of the coating surface and calculating the surface energy,the hydrophobic mechanism of the coating surface was discussed.At the same time,the adhesion of the coating reaches Class 1.Thermal stability and dielectric properties are both better than those of GFRP substrate.This research also research the evolution of the weather resistance of the fluorosilicon superhydrophobic coating.The influence of enviroment factors on the water contact angle,surface energy,chemical structure and surface micro-morphology of the composite coating and performance evolution of the coating material was systematically analyzed by UV aging test,salt spray corrosion acceleration test,high temperature-low temperature alternating cycle test and outside natural aging test.Results show that the salt spray corrosion has the greatest effect on the hydrophobicity of fluoro-silicon superhydrophobic coating.The water contact angle of the coating after 500 hours of salt spray corrosion reduced by 39.05°,compared with that before corrosion.Finally,the influence mechanism of aging of the coating on hydrophobicity was analyzed.Results shows that the destruction of the microstructure of the material and the increase of hydrophilic groups were two main reasons that causing the decrease of the coating performance.