Fabrication and characterization of ultra-water-repellent alumina-silica composite films

Ultra- water- repellent ( UWR) films were prepared by microwave plasma- enhanced chemical vapour deposition using trimethylmethoxysilane and aluminium (III) diisopropoxide ethylacetoacetate ( ADE) as raw materials. The film was mainly composed of silica and alumina and was apparently transparent. The film thickness was approximately 500 nm. The sample surface was treated with an organosilane in order to introduce hydrophobic groups. The hydrophobic modification led to a water contact angle of more than 150., whose value corresponds to the UWR surface. The hardness of film with an optimized A1 content was significantly improved compared with that without A1. The maximum hardness was 1.71 GPa. In consequence, we successfully prepared an UWR film in the silica - alumina system.