INVESTIGATING THE EFFECTS OF TILT ANGLES ON SELF-CLEANING OF SUPERHYDROPHOBIC COMPOSITE SURFACES

摘要

Superhydrophobic surfaces are of great interest to many industries, such as corrosion, coating, dewettability, deicing, construction, and self-cleaning surfaces because of their extremely repellent surface features against water and other liquids. The major requirements of the superhydrophobic surfaces include a very low surface energy and micro and nanoscale hierarchical roughness of the surfaces. The water contact angle of a liquid drop on the substrate surface is between 150 and 180°, where dirt/dust can easily fall off with water after a certain surface tilt angle is reached. This may be very critical for composite aircraft and wind turbine blades to keep them clean continuously throughout the seasons. In the present study, pre-preg carbon, glass and Kevlar fiber composite panels were prepared using a vacuum coven for curing, and two layers of superhydrophobic coatings (～50μm) were applied on those composite panels for self-cleaning purposes. Graphite powders (dusts) were sprinkled on the prepared composite panels prior to the water spraying at a known distance (40 cm). During the tests, effects of surface tilt angles (e.g., 7.5, 15, 30, 45 and 60°) were investigated in detail for the self-cleaning of the composites. It was observed that at higher tilt angle, self-cleaning efficiencies of the superhydrophobic composite surfaces were considerably improved. The test results may be useful for the future directions of self-cleaning of composite materials and devices for different industrial applications (e.g., aircraft, wind turbines, automobiles, ships, construction, etc.).