Davis Alexander, Yeong Yong Han, Steele Adam, Bayer Ilker S, Loth Eric
Department of Mechanical and Aerospace Engineering, University of Virginia , Charlottesville, Virginia 22904, United States.
ACS Appl Mater Interfaces. 2014 Jun 25;6(12):9272-9. doi: 10.1021/am501640h. Epub 2014 Jun 10.
A method to reduce the surface roughness of a spray-casted polyurethane/silica/fluoroacrylic superhydrophobic nanocomposite coating was demonstrated. By changing the main slurry carrier fluid, fluoropolymer medium, surface pretreatment, and spray parameters, we achieved arithmetic surface roughness values of 8.7, 2.7, and 1.6 μm on three test surfaces. The three surfaces displayed superhydrophobic performance with modest variations in skewness and kurtosis. The arithmetic roughness level of 1.6 μm is the smoothest superhydrophobic surface yet produced with these spray-based techniques. These three nanocomposite surfaces, along with a polished aluminum surface, were impacted with a supercooled water spray in icing conditions, and after ice accretion occurred, each was subjected to a pressurized tensile test to measure ice-adhesion. All three superhydrophobic surfaces showed lower ice adhesion than that of the polished aluminum surface. Interestingly, the intermediate roughness surface yielded the best performance, which suggests that high kurtosis and shorter autocorrelation lengths improve performance. The most ice-phobic nanocomposite showed a 60% reduction in ice-adhesion strength when compared to polished aluminum.
展示了一种降低喷涂聚氨酯/二氧化硅/氟丙烯酸超疏水纳米复合涂层表面粗糙度的方法。通过改变主要浆料载体流体、含氟聚合物介质、表面预处理和喷涂参数，我们在三个测试表面上实现了算术表面粗糙度值分别为8.7、2.7和1.6μm。这三个表面呈现出超疏水性能，偏度和峰度有适度变化。1.6μm的算术粗糙度水平是采用这些基于喷涂的技术所生产出的最光滑的超疏水表面。这三个纳米复合表面以及一个抛光铝表面在结冰条件下受到过冷水喷雾冲击，结冰后，对每个表面进行加压拉伸试验以测量冰附着力。所有三个超疏水表面的冰附着力均低于抛光铝表面。有趣的是，中等粗糙度表面表现出最佳性能，这表明高峰度和较短的自相关长度可提高性能。与抛光铝相比，疏冰性最强的纳米复合材料的冰附着力强度降低了60%。
