Superhydrophobic Surface Preparation On Silicon Substrate And Its Reduction Characteristic

With continuous development of micro-fluid systems recent years, researchers committe to the study of drag reduction measures of micro-fluid systems. Different with macroscopic systems, fluid resistance of the micro-fluid system mainly comes from the adsorption of molecular force of electrostatic, van der waals forces between the fluid and the wall. Traditional measures for drag reduction is not applicable, reducing the adsorption between the micro-fluid surfaces and the fluid is more suitable. Super-hydrophobic surfaces can effectively reduce the adsorption between fluid and wall of micro-fluid systems, in the meantime, the special way of droplets on the superhydroph-obic surface lead to velocity-slip when fluid flowing through the wall, and achieve drag reduction.Mainly work of this paper as follows:1. Hydrophobic or superhydrophobic surface was built on silicon surface by combining etching and low surface material modification. Relationship between surface wettability and surface texture was analysed by comparing with theoretical models. Results show that smaller spacing and greater height of texture can easilier build super-hydrophobic surface; material with different low surface energy has different influence on wettability. In the experiment, four self-assembled monolayers as low surface energy materials were chosen to modify material surface, the relationship between the apparent contact angle that prepared in the experiment as follow:FDTS> FOTS> OTS> MPS.2. Multifunctional friction and wear tester was used to analysis friction drag red-uction effect of FOTS and influence of UV irradiation on the drag reduction. Results showed that:the friction coefficient of silicon surface which modified by self-assembled monolayers largely reduces, which shows good drag reduction effect. In addition UV irradiation can reduce the drag reduction effect of self-assembled monolayers,and irradiation time longer, serious consequences more.3. Simulation of superhydrophobic surface drag reduction in micro-channels based on fluent software shows that:the phenomenon of velocity slip happenning when fluid flows through superhydrophobic surface, so superhydrophobic surface can achieve very good drag reduction effect in the micro-channels of the micro-fluid system, what’s more, the drag reduction effect is more obvious with greater texture spacing, the maximum drag reduction ratio can reach 25.27%.