Properties of optical coatings formed on silicate glass from silica sol with alumina sol additive

The addition of 0.1—0.5 mol.% of alumina sol causes the increase in hardness of single-layer optical coatings, produced on silicate glass from silica sol at gel setting temperatures of 60—80 °C, from F—H to 7H—9H. Small concentrations of the additive do not affect the light transmission of the coated glasses. Atomic force microscopy has shown the coating surface to be homogeneous, the surface roughness not exceeding 4.0 nm.