Preparation Of The Superhydrophobic Nano-TiO₂/ Polysiloxane Resin Composite Coating And Research Of Its Performance

The greatest characteristic of superhydrophobic coating is its strong rejection capability to the aqueous solution.A layer of air film was generated between the coating and aqueous solution when the coating was contacted with aqueous solution,and this air cushion can effectively prevent aqueous solution to permeate into the inside coating.So using the superhydrophobic coatings for metal corrosion protection became one of the hot research topic at present.Here the rutile nano-TiO₂ and polysiloxane resin was chosen as the research object.The nanomaterials are used to provide the micro/nano structurer which was essential for super hydrophobic surface,and the polysiloxane resin was used as a binder to increase the binding force of nanoparticles and the base material.A superhydrophobic coating with good mechanical properties and corrosion resistance was built by this means.The rutile nano-TiO₂ particles were modified by triethoxyoctylsilane.The surface topography of the modified-TiO2 was observed by SEM.The hydrophobicity and thermal stability of the modified nano-TiO₂ were detected by contact Angle measurement instrument and thermogravimetric analyzer.The results are as follows:1.the prepared nano-TiO₂ formed a rough micro/nano structure due to the agglomeration;2.the superhydrophobic TiO₂ was obtained when both the particle size of the rutile TiO₂ was less than 100 nm and the modification time is higher than 1.5 h;3.the superhydrophobic TiO₂ had a contant angle of about 151°and a sliding angle of about 3°;4.the mass loss is only 0.5%of the sample under500°C?The above data show that the prepared superhydrophobic TiO₂ particles hve an excellent hydrophobicity and thermal stability.Two kinds of coating system were constructed using the superhydrophobic TiO₂ and polysiloxane resin.The first kind of coating system:firstly,the resin was coated onto the surface of base material,then the superhydrophobicTiO₂ particles were splashed onto the surface of resin,and the powder/resin double-layer coating system was obtained after curing.The abrasion test,immersion test and electrochemical experiments were carried put to characterize the wear resistance and corrosion resistance of the coating.The results are as follows:1.the quality of the coating damage was little and the coating could maintain a contact angle of about 151°after abrasion test;2.There was no obvious change on the surface of the coating and the coating still had a resistance value of about 1.628×10⁵?·cm² after the coating was immersed into 3.5%NaCl for 3 days.The second kind of coating system:firstly,the superhydrophobic TiO₂ particles and the resin were mixed according to the certain proportion of 2:1.Then the mixture was coated on the surface of base material and the blending coating system could be obtained after curing.The similar methods were used to evaluate the performance of the composite coating.The results are as follows:1.The composite coating can still keep superhydrophobic under 160°C;2.The surface of the coating had no obvious changes and still keep the superhydrophobic under the environment of160°C,90%RH;3.There was no crack or rust on the surface of the coating after immersed for 16 days;4.The impedance value is still as high as 1.29 x 10⁶?·cm² after immersed for 3days.The above data show that the two kinds of coating system all have an excellent durability and corrosion resistance.