| As a new type of functional material,the superhydrophobic material has always been one of the most active research topics because of its unique properties,such as self-cleaning,anti-icing,corrosion resistance and drag reduction.In this paper,SiO2 modified by materials with low surface free energy are selected as filler particles and filled into different resin matrixes,then,a superhydrophobic/ultra-slippery coating is obtained by multiple thin spraying and dip coating processes.The SiO2 particles and the prepared sample coatings were characterized by SEM,TEM,FTIR,etc.,as well as the wettability,corrosion resistance,and drag reduction properties of the sample coatings were investigated and analysised by contact angle tester,electrochemical workstation and circulating sink device.The nano-SiO2 particles were prepared by the simple St?ber method.After being modified with HDTMS,they were filled into the PVDF matrix resin,then the mixture was sprayed on the pretreated substrate by multiple thin spraying process to obtain a superhydrophobic coating.By comparison,we found that the preheating and spraying processes were uesful to obtain a micro-nanomorphology.The test results of SEM and contact angle tester showed that the contact angle increased with the increase of SiO2particles.When the proportion was up to 80 wt%,the contact angle was as high as 156°.The thickness of the coating was about 30μm,the sandpaper grinding test proved that the thickened coating had a certain performance of scratch resistance.The results of the electrochemical workstation and the circulating sink device tests showed that the sample coating had excellent corrosion resistance and drag reduction performance under water.The nano-SiO2 particles were simply modified with HMDS in one step and the reaction took place in a confined place,then repeated the previous steps to obtain a superhydrophobic coating.The test results of SEM and contact angle tester showed that the contact angle increased first and then decreased with the increase of SiO2,when the amount of SiO2 was up to 50 wt%,the contact angle could greatly reach to 166°.Thickness gauge showed that the thickness of the prepared coating was approximately 20μm.The prepared coating was immersed in dimethyl silicone oil to obtain a ultra-slippery coating surface,and then the contact angle was measured to be 104°as well as the roll angle was 4.47°.The ultra-slippery coating was tested with a laboratory-made simulated seawater circulation agitation device,its result showed that the ultra-slippery coating had a good durability.After three months soaking in 3.5 wt%NaCl aqueous solution,the ultra-slippery coating still had an impedance modulus as high as 1.4×109,which indicated that it had a good corrosion resistance.The results of the circulating sink tests showed that the sample coating had a significant drag reduction performance under high speed flow conditions.We chosen PDMS as a resin matrix to obtain a coral reef-like superhydrophobic coating by multiple thin spraying process.When the amount of SiO2 was up to 35 wt%,its corresponding contact angle was 162°.Thickness gauge showed a result that the thickness of the prepared coating was about 100μm.The result of electrochemical workstation showed that the sample coating has a good corrosion resistance.When the sample was exposed to high and low temperatures as well as acid and alkali environment for a while,it still had a good hydrophobic property.Friction and wear experiment proved that the sample coating had good mechanical stability.The sample paint was sprayed on different substrates and the water drop test showed that the sample coating had excellent multi-substrate applicability.The results of anti-sludge suspension and circulating sink tests showed that the sample coating had a better drag reduction effect which was superior to the sample coatings of the previous two chapters. |
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