Research On The Design?Fabrication And Reduction Resistance Analysis Of Micro Structure Array Based On The SU-8 Negative Photoresist

Drag reduction underwater is a challenging research field,it has become a research focus because of its great military value and potential economic value.The domestic and foreign researches on drag reduction have already made great progress,but how to make a surface with excellent drag reduction properties is still the key point of this study.In this paper,a new method which combined the principle of the micro-bubbles produced by electrolysis and the principle of hydrophobic surface is studied in the aim of drag reduction.The contents include:1.The theories of hydrophobic were researched.Firstly,the relationship between surface energy and surface tension was elaborated by calculation;followed by a brief introduction of the traditional hydrophobic theories,from Young's equation to Wenzel model and Cassie model;besides,the force analysis to the droplet on the smooth surface was carried out,especially to the droplet in Cassie state.Finally,the factors which influenced the rolling angle were analyzed briefly.2.The technological process and parameters of SU-8 negative photoresist were studied.Firstly,The advantages of the structures made by SU-8 were analyzed,and the reasons why SU-8 was selected to make hydrophobic structure were given;then the technological process and processing parameters of making SU-8 micro structure were studied in our laboratory environment,and the value of the final process and parameters were determined;what's more,the trapezoidal characteristic of the SU-8 micro structures was introduced;finally,we study the relationship between the exposure time and the size of the structure,and we determined the optimal exposure time.3.The contact angle tester was put up,and the method which could test the contact angle was determined,and the error sources of the contact angle tester were analyzed.Then the groove structure,umbrella type structure and Salvinia biomimetic hydrophobic structure were designed,fabricated,and the contact angle of each sample was tested.The test results showed that the hydrophobic performance of the sample was excellent,which laid a solid foundation for the preparation of the drag reduction surface.4.The device which was used to the drag reduction was produced,and then the sample was fabricated on the electrode layer and the effect of drag reduction of the sample was tested.Through calculation and analysis based on the experimental data,We obtained that the drag reduction rate could reach to 7.38%.The experimental results showed that the effect of drag reduction of the hydrophobic structure combined with electrolytic reduction was better than the hydrophobic surface alone,and it proven the feasibility of the combination of micro cavitation and hydrophobic drag reduction.