Effect Of Modified SiO₂ On Hydrophobicity And Anti-Icing Performance Of Coating

The research and application of superhydrophobic surfaces have made major breakthroughs in experiments and actual production.However,the interaction between the surface micro-nano-scale rough structure and hydrophobicity is still worthy of our further study.To this end,the paper will prepare modified monodisperse submicron silica microspheres and study its influence on the hydrophobicity of the coating.in order to obtain a better micro-nano structure,study the impact of the mixing ratio of modified silica with different particle sizes on hydrophobicity;on this basis,the superhydrophobic silica dispersion was sprayed on the surface of the semi-cured fluorosilicone resin to prepare a superhydrophobic coating.And the anti-icing performance and long-term performance of the coating were tested and analyzed.The results showed the long-term and anti-icing properties of the superhydrophobic coating have been significantly improved.The main results of the experiment are as follows:The preparation process of silica with controllable particle size was explored.The particle size of silica can be controlled by parameters such as the volume ratio of ammonia water to TEOS,reaction temperature,and the volume ratio of TEOS to deionized water.Three kinds of silane coupling agents are used to modify silica particles.It was found that the three modifiers all increased the contact angle between the particles and water and improved the hydrophobicity of the particles.Among them,PFOTES had the best modification effect.On this basis,an orthogonal experiment was designed to optimize the modification process of PFOTES.When the modification temperature is 90?,the ratio of modifier to nano silica is 1:1,the modification time is 1h and the modified particles have the best hydrophobicity.The influence of monodisperse silica with different particle sizes on the hydrophobicity has been studied,and the results show that the hydrophobic angle of the modified silica is the largest when the particle size is 150nm,and the average hydrophobic angle is 152.8°.The effect of different mixing ratios of modified silica on the hydrophobicity of the coating film was studied.The microscopic morphology of the coating film was characterized by SEM,the roughness was measured by a laser scanning confocal microscope,and the relationship between the test results and the hydrophobicity was analyzed.The results show that when the mixing ratio is(550nm:330nm=3:1),the hydrophobic angle is the largest,with an average angle of 155.5°.And the wettability of the prepared superhydrophobic coating film is evaluated,and the maximum CA=162.1°,and SA=4.3°.And the calculated surface free energy of the coating film is only 9.7 m J/m2,which is much smaller than the surface tension of water droplets,which explains why the superhydrophobic surface is not easy to be wetted.In order to enhance the long-term performance of the super-hydrophobic coating surface,the experiment directly sprayed the modified super-hydrophobic silica ethanol dispersion on the surface of the semi-cured HLR-Si fluorosilicone resin,and under the strong interaction of the ethanol volatilized and the resin and the modified silica microspheres,micron-level rough structures such as resin-coated silica and cross-linked aggregation of silica microspheres are formed.A superhydrophobic coating with an average hydrophobic angle of 150.6°was prepared.The hydrophobic angle test and SEM and laser confocal test of the coating were carried out to further characterize the micro morphology of the coating and analyze the relationship between roughness and hydrophobicity.And it is proved that the coating has good long-term effect by the sanding experiment.The coating was subjected to low-temperature freezing test.The super-hydrophobic coating B₅(550nm:330nm=3:1)has the strongest ability to delay icing and the freezing completion time of the coating is 117s at-15°C,and the anti-icing performance is better.