Abstract: Double-layer antireflective(AR) coatings on K9 glass with excellent environmental resistance and abrasion-resistance were designed and prepared. Using tetraethylorthosilicate(TEOS) and titanium tetraisopropoxide(TTIP) as precursor, respectively, SiO₂ and TiO₂ sols were prepared via sol-gel process with hydrochloric acid as catalyst. SiO₂-TiO₂ composite films were prepared by mixing the SiO₂ and TiO₂ sols and then dip-coating on the substrates. The refractive indices of the composite films were controlled by adjusting the SiO₂/TiO₂ ratio and the thickness was controlled by adjusting the dip-coating speed. It was found that the maximum transmittance of the double-layer AR coatings reached 99.9% and could be adjusted to match a specific wavelength. The transmittance did not decrease after abrasion test, indicating an excellent abrasion-resistance of the AR coating. Hydroxyl terminated hexamethyldisiloxane(HMDS) treatment was further performed to improve the hydrophobicity, the environmental resistance and durability of the AR coatings.

Key words: Thin film design, Environmental resistance, Abrasion-resistance, Double-layer antireflective coating, High transmittance, Hexarnethyldisiloxane(HMDS)