Numerical And Experimental Study On The Fabrication Of Micro-dimple Array By Electrodeposition With Colloidal Particle Mask

Functional surfaces with microstructures on the surfaces have many applications in many scientific fields due to its special surface properties,such as hydrophobicity,biocompatibility and wear resistance.The processes for the formations of microstructures on functional surfaces have drawn much attention of researchers all over the world in the last decades.At present,the processes for the formation of microstructures just can be carried out on flat and regular curved surfaces limited by technological processes and the fabrication of masks used in the formation of microstructures.Hence,it's a challenge to fabricate microstructure on irregular surface.In this work,a process for fabricating microstructure by electrodeposition using colloidal particle mask was presented to solve the problems of fabricating microstructure and the attachment of mask on irregular workpiece surface.From the angle of theoretical research,numerical models of the fabricating of microstructure by electrodeposition using colloidal particle mask were built to study the formation of microstructure and the distribution of electric field.In addition,experimental studies of fabricating microstructure by electrodeposition on flat and cylinder surfaces using polystyrene colloidal particle mask were conducted,and the wettability of deposited layers were evaluated.The main research contents and results are as follows:(1)Finite element simulation models of fabricating microstructure by electrodeposition using colloidal particle mask were built and calculated under primary,secondary and tertiary current density.The simulation results show that: deposited layer with roughness surface and anomalous micro-dimple structure were obtained under primary current density;when simulating under secondary density,smooth curved deposited layer and circular micro-dimple were formed;while flat and circular micro-dimple were obtained under tertiary current density.(2)Experiments of the colloidal particle masks self-assembled by electrophoretic method and electrodepositing on planar workpiece surfaces using the colloidal particle masks were studied.The experiments results showed that: colloidal particle masks could be obtained by electrophoretic method,and colloidal particle mask with good quality can be formed by adjusting the voltage and the electrophoretic time.By electrodepositing using colloidal particle mask,deposited layers with micro-dimples arrays were obtained.The uniformity of micro-dimples arrays were influenced by the electrodeposition time and current density,and could be improved obviously through using colloidal particle mask after heat treated under a suitable temperature.(3)The experimental studies on colloidal particle mask formed by interface transfer method and electrodepositing using colloidal particle mask were carried out on cylindrical workpiece surface.The results showed that: colloidal particle mask could formed on cylinder workpiece surface;after electrodeposition and the removal of colloidal particle mask,deposited layer with micro-dimples array was formed,and the quality of deposited and micro-dimple were influenced by the curvature of cylinder workpiece,electrodepositing time and current density.(4)The wettability of deposited layers were measured to analyze the influence of micro-dimples arrays on the wettability of deposited layers obtained by electrodepositing using colloidal particle masks.The results measured on the flat deposited layers show that: the characters of deposited layers were affected by the center distance L between micro-dimples,when the L=1?m,the flat deposited layers were hydrophobic surfaces and the hydrophobicity increased with the increase of diameters of micro-dimples;while hydrophilic surfaces were obtained when the L=1 and 5?m,and the hydrophilicity of deposited layers increased with the increase of micro-dimples diameters.The measurement results on cylinder workpieces surfaces show that: the hydrophobicity of cylindrical deposited layers was influenced mainly by the curvatures of cylinder workpieces and micro-dimples diameters,and increased with the increase of curvature of cylinder workpieces,while increased firstly and then decreased with the increase of micro-dimples diameters.In summary,periodic micro-dimple array could be fabricated effectively on flat and curved metal surface by electrodeposition using colloidal particle mask,and the wettability of workpiece was improved obviously.The process for the formation of micro-dimple array by electrodeposition using colloidal particle mask is helpful to solve the problem of fabricating microstructure on free-curved metal surface.