Laser Processing Of Non-uniform Wettability Surface And Research On Its Characteristics

The non-uniform wettability surface has important application value in the fields of fog collection,droplet transportation,etc.However,the preparation process of the non-uniform wettability surface has problems such as time-consuming,complicated,and poor material versatility.The thesis uses an efficient and versatile laser processing method to prepare a nonuniform wettability surface through two laser etchings combined with low surface energy modification,focusing on the wettability,practical application and application of the nonuniform wettability surface.Timeliness is analyzed and researched.The main contents include:Using laser etching combined with fluoroalkylsilane(FAS)solution to modify the low surface energy to construct a superhydrophobic surface,and then using secondary laser etching to prepare superhydrophilic patterns such as dotted/linear grooves,thereby Obtain a nonuniform wettability surface.Using this process,the required superhydrophilic pattern can be accurately obtained by computer-side control of the laser.Characterize the micro-nano structure and chemical composition of the prepared nonuniform wettability surface with dotted/linear-shaped superhydrophilic grooves,and then measure the contact angles of droplets of different volumes on dotted/linear-shaped grooves with different sizes,and the sliding angle is tested and measured.The results show that the prepared dotted grooves have strong controllable adhesion,and the linear grooves have significant anisotropic adhesion.Combining the adhesion of the superhydrophilic region and the water repellency of the superhydrophobic region,a variety of practical applications are performed on non-uniform wettability surfaces,including the preparation of patterned surfaces,droplet transportation,droplet grabbing and mixing.The fog collection test was carried out on the surfaces of aluminum,copper,steel and titanium.The results show that the fog collection efficiency of the non-uniform wettability surface is improved to a certain extent compared with the uniform superhydrophilic surface,the uniform superhydrophobic surface and the untreated surface.Among them,the non-uniform wettability steel surface has the greatest degree of improvement,respectively : 33.88%,55.98%,63.44%.In addition,among the patterned surfaces of the four metals with non-uniform wettability,the fog collection efficiency of steel is also the highest.Study the time stability of non-uniform wettability surfaces at different temperatures.Firstly,the change trend of the contact angle and sliding angle of the droplet on the superhydrophilic area of the non-uniform wettability surface under different temperatures is explored,and the surface micro-nano structure and chemical composition of the superhydrophilic area are compared and analyzed.The results show that the aging rate of the superhydrophilic area of the non-uniform wettability surface is significantly greater than that of the uniform superhydrophilic surface;the reason for the wettability change comes from the adsorption of non-polar C-C/C-H/C-Si functional groups in the test environment air and cross contamination with surrounding superhydrophobic areas.Finally,a fog collection test was carried out on non-uniform wettability surfaces with different aging degrees to explore the effect of timeliness on its application.The results show that as the aging degree of the superhydrophilic area increases,the fog collection efficiency gradually decreases,and when the samples are stored at low temperature,the fog collection efficiency can still be maintained at a high level.