Preparation Of Superhydrophobic Micro-nanocomposite Structure On Metal Surface By A Screen Printing Aided Electrochemical Machining Method

The metal engineering materials have been covered many fields of our production and life.The study of interfacial materials was focused on the wettability of metal materials,and it has been widely applied in the fields of corrosion resistance and oil-water separation.In this study,the electrolytic mask was prepared by silk-screen printing technology,and the superhydrophobic copper sheet with micro-nano composite structure was prepared by electrolytic processing.The anti-frosting property of superhydrophobic copper sheet was studied.The main contents are as follows:The subtle research on the screen printing of technology and parameters: There are many factors affecting the screen printing precision.This thesis analyzed the screen selection,ink properties and substrates.The limitations of various formulas of minimum dot calculation are analyzed.The minimum dot size is calculated based on the minimum dot calculation formula.And on this basis the calculation formula of the dot interval was exported.The spreading characteristics of inks on coated paper and copper sheet were analyzed.The ink viscosity and dot area ratio of originals were important factors influencing ink transfer and dot gain,and they are also the key to the preparation of fine electrolytic masks.The influence of the ink viscosity and screen dot area ratio on the mask size was discussed in the experiment.A mask with a moderate size can be obtained by using a 30% dot area ratio and a 1000-1600 cps ink on the copper sheet.The screen printing aided electrochemical machining method preparing micro-nano composite structure.In this thesis,a method for preparing microstructures by silk-screen printing assisted electrolytic machining is proposed.The feature of this technology is to introduce the printing technology into the electrochemical machining surface microstructure.The method solved the complex problem of the traditional mask electrolysis method for making a mask,and has a very broad application prospect.An electrolytic mask was printed on the surface of the copper sheet by screen printing.The mask size was between 140 ?m and 160 ?m,and the mask interval was between 80 ?m and 110 ?m.The effects of voltage and electrolyte concentration on the machining precision are discussed.Taking into account the electrolytic precision of the microstructure,the appropriate microstructure height and corresponding tilt angles of 23.7 ?m and 11.2� were obtained by electrolysis for 120 s with a voltage of 5 V and the electrolyte concentration is 5 wt%.Preparation and property of superhydrophobic micro-nano structure on copper.This thesis presented two methods for preparing micro-nano structure: electrolytic oxidation and one-step electrolysis.The first one: the microstructure obtained by using a ferric chloride solution etching to obtain a micro-nano structure.The second one: adding the ferric chloride solution into the electrolyte to form the mixed solution of sodium nitrate and ferric chloride.After the electroplated copper sheet has been electrolyzed,the micro-nano structure can be obtained in one step.The superhydrophobic copper sheet was prepared by electrolytic oxidation method with a maximum contact angle of 155� and a minimum roll angle of 6�.The maximum contact angle of the superhydrophobic copper sheet by one-step electrolysis was 153� and the minimum roll angle was 3�.The effect of ferric chloride concentration on the contact angle was discussed in the electrolytic oxidation method.The influence of voltage on the contact angle was discussed in the one-step electrolysis method.The superhydrophobic copper prepared by the two methods can effectively delay the formation of moisture on the surface of the copper sheet and have good anti-frosting performance.