Anti-glare coatings deposited on sheet glass by sol-gel processing

Abstract

A sol-gel derived cobalt oxide-zirconium oxide coating (100 to 200 nm thick) on glass, which can cut off hght in the visible range almost uniformly in a single-layer (and within ± 1 to 2 % in a 2-layer) system has been described. The suitability of the coating in acting as a glare-protective aid for human eyes is indicated. Transmission and specular reflection spectra of the coatings indicate that first, the cobalt is not accepted by the zirconia matrix in the ionic form, and second, the near-neutral transmission in the visible range has contributions of both reflection by the zirconia host and absorption by the cobalt (possibly in a dispersed oxide form). Transmission electron microscopy indeed reveals the presence of a finely dispersed amorphous phase throughout the matrix. Using a draining technique, (40 x 40) cm2 coatings with smooth and uniform visual appearance have been obtained in a routine way.