用于固液界面减阻无氟超疏水表面制备新方法

现阶段超疏减阻表面常用低表面能的氟化剂制备不绿色环保,为实现超疏水减阻表面的无氟化,提出一种可用于固液界面减阻的无氟铝合金超疏水表面制备新方法.首先,采用化学腐蚀技术在铝合金基底上快速制备微纳量级表面粗糙结构,再利用天然松香溶液和炭黑悬浊液进行表面修饰改性处理,替代传统氟化物.在表征上,分别采用扫描电子显微镜(SEM)、接触角测量仪和X射线能谱分析(EDS)来分别表征微观结构尺寸、表面润湿性和元素分析.通过不断优化表面结构和修饰溶液浓度,在铝合金样品上制备出接触角为155°,滚动角为1.38°处于Cassie模型状态的超疏水表面.结果表明:所构建的无氟超疏水表面经受80次浸没取出循环完整性良好,此外在速度为1.4 m/s连续水滴冲击3 h后仍保持良好的超疏特性;通过减阻冲刷实验装置测试,在0.5～3.5 m/s冲刷流速范围内,本方法制备的无氟超疏表面可达到20%～30%减阻率,从而验证了新方法在超疏减阻应用中的有效性.整个制备过程简单、成本低廉且无氟环保,利于规模化生产应用.

A new method for fluorine-free superhydrophobic surface used for drag-reduction at solid-liquid interface

At present, the preparation of superhydrophobic surface with fluorinating agents is not environmentally friendly. To solve this problem, a new method for fabricating fluorine-free superhydrophobic surface on aluminium alloy for drag-reduction at solid-liquid interface was proposed. First, chemical etching technology was used to fabricate micro- and nano-scale surface roughness on the substrate. Then natural rosin solution and carbon black suspension were used to modify the surface to replace traditional fluoride. In terms of characterization, scanning electron microscopy (SEM), contact angle measurement instrument, and X-ray energy spectrum analysis (EDS) were used to characterize the microstructure, surface wettability, and elemental analysis respectively. By continuously optimizing the surface structure and the concentration of the modified solution, the superhydrophobic surface with a contact angle of 155° and a rolling angle of 1.38° in the Cassie model state was achieved on the substrate. The experimental results indicated that the surface with the new method had good integrity after 80 cycles of immersion and extraction. In addition, it maintained good superhydrophobic property under continuous water drop impact at the velocity of 1.4 m/s for 3 h. Through the test of drag-reduction and scouring experiment, compared with untreated surface, the drag-reduction rate of the fluorine-free superhydrophobic surface could reach 20%~30% in the scouring velocity range of 0.5~3.5 m/s, which verified the effectiveness of the new method. The whole process is simple, cost-effective, and environmental friendly, which is conducive to large-scale production and application.