摘要
A rapid prototyping process was presented to fabricate a nylon honeycomb microstructure coated with parylene C.The surface structure was designed to obtain a hydrophobic surface using the volume of fluid(VOF)model.With the micro-molding technique,the contact angle of the polymer surface could be designed and fabricated by changing the different microstructure surface diesteel mold inserts.For the honeycomb(20μm width and 60μm depth)microcavity side wall,an average micro-molding filling percentage of 95% could be achieved by using a three-section constant-pressure molding process.The solid surface wettability is governed by both the geometrical microstructures and the surface energy.A 2μm parylene C layer was deposited on the nylon honeycomb microsurface to reduce the surface energy.To design honeycomb structures with different microcavity densities,the contact angle of these artificial surfaces could change from 91°to 130°.From a comparison of the contact angle measurements with the different models,the honeycomb-structured microsurface could be described by the Cassie–Baxter model.The errors between the VOF simulation and the measured data were<10%.The drag reduction performance of the honeycomb microplates was investigated in a water tunnel with a high Reynolds number(from 0.5×10^(6) to 4.6×10^(6)).As a result,the honeycomb microplates showed a maximum drag reduction rate of 36±0.6%in comparison with the bare plates in such turbulent flow.Benefiting from the replaceable mold insert,more designable microstructure polymer surfaces can be manufactured by this rapid prototyping technique.
基金
The research was granted by the Chinese National Nature Science Foundation(Grant No.41571309).
