Super‐Water‐Repellent Al2O3 Coating Films with High Transparency

Abstract
We have prepared transparent, super-water-repellent coating films of alumina on glass plates by a combination of geometric and chemical approaches. The contact angle for water in the films was 165° and the transmittance for visible light was higher than 92%. A roughness of 20 to 50 nm was obtained, which is too small to scatter visible light, while the degree of roughness was great enough to enhance the water-repellent properties together with the chemical effect of a fluorine-containing agent and gave a super-water-repellent surface. The coatings have great potential for practical applications such as eyeglasses, cover glasses for solar cells, windshields of automobiles, and so on.