Research Of Anti-icing Coating For Metallic Substates

As we know,icing on substance surfaces can cause serious problem in common life and economic activities,such as power transmission,communications network,aviation,navigation and high-speed train transportation.To address this formidable problem,various de-icing techniques including mechanically removing,heating or spraying chemicals have emerged.However,currently available techniques may result in energy consumptions and environment pollutions.Recently,anti-icing coating is considered to be a good candidate.Comparing with other methods,it has many characteristics and advantages,such as convenient and economical.Thereofore,to develop anti-icing coat holds great potential in industrial application.Fluoropolymer is preferred among the anti-icing coat for its unique characteristic,including super-smooth surface with nano-structure infiltrated and low-viscosity perfluorinated lubricating fluid.Unfortunately,it always has low adhesion with its substance,resulting in a short life of the coat.In this paper,fluorosilicone sol was prepared by mixing the(Heptadecafluoro-1,1,2,2-tetradecyl)trimethoxysilane(FAS-17)with(?)3-Aminopropyl triethoxysilane(KH-550).The coat prepared by such sol was high-hydrophobic(CA=119°).Then,aqueous epoxy coat was modified by mixing with the fluoroilicone sol through reaction between amide groups and epoxy groups.As a result,aqueous fluorinated-epoxy coat was obtained.The contact angle of water against such coat was about 115°,which is almost highest value(120°)on the flat surface.XPS and EDX characterization confirmed that fluorin containing molecules moved to the surface of coat during drying and cure procedure.In order to further improve its hydrophobicity,silica nanoparticles were coated on metal surface and then modified with above fluoroilicone sol.As a result,super-hydrophobic surface was obtained.After the surface being infiltrated with low-viscosity perfluorinated lubricating fluid,a molecular smooth surface was formed and the contact angle hysteresis was greatly reduced(0.5°).By anti-freezing tests,when the substrate surface was-10 ℃,fluorinated epoxy coat significantly delayed the freeze time of a extra added water drop to 800 s,while the original copper surface was only 40 s Moreover,freezing time would become smaller as the temperature decreased.With the temperature further decreasing to-15 ℃,the freezing time of condensate approached closely to that on the pure copper.At-10℃,fluorinated epoxy coat sligthtly delayed the freeze time in situ condensed drops to 125 s,while the copper surface was 60 s.This implies that under condensation state,the hydrophobic coat almost had little effect on icing delaying.However,at-30 ℃,it could largely reduce the ice adhesion strength up to 50%.Compared with above hydrophobic surfaces,superhydrophobic and super-smooth surface have both better performances in delaying water drops icing and reducing the ice adhesion strength.At-30 ℃,the adhesion strength of extra added drops on superhydrophobic surface is only one third of strength that on pure stainless steel surface,while the strength on the super smooth surface is only one fifth of that on pure stainless steel surface.In delaying ice formation,superhydrophobic and super-smooth surface are both better than hydrophobic coat.While the substrate surface was-10 ℃,superhydrophobic surface significantly delayed the freeze time in situ condensed drops to 600 s,super-smooth surface increased to 1000 s,while the copper surface and hydrophobic surface is only 60 and 125 s.When the substrate surface was-20 ℃,superhydrophobic surface delayed the freeze time of a extra added water drop to 110 s,super-smooth surface increased to 120 s,while the original copper surface is only 7 s.This implies that superhydrophobic and super-smooth surface have good performances in delaying water drops icing and reducing the ice adhesion strength.