Hybrid SiO2–ZrO2 coatings for restoring and repairing glasses damaged by sandblasting

Abstract

The purpose of this work was to study the repairing of defect produced by sandstorms on the surface of car windshields and solar panels, by deposition of thin transparent sol-gel layers. Different silica-zirconia films (100-x SiO2 - x ZrO2, x = (10, 15, 20, 25 and 30 mol %) were prepared by the sol–gel process using TEOS and MTES as silica precursors and incorporating two different colloidal suspensions with silica or zirconia nanoparticles. The silica-zirconia sols were deposited by dip coating on soda-lime glass samples previously eroded by sandblasting. Film thickness and homogeneity were evaluated by ellipsometry and AFM, and the optical and mechanical properties were studied by UV–vis spectroscopy, the hardness by microhardness, and the roughness by tactile profilometer. The sol-gel coatings present a good quality and are able to restore the optical and mechanical properties of sandblasted samples thus increasing the service life. The incorporation of zirconia particles to SiO2 coatings increases the refractive index, from 1.42 to 1.57. Moreover, optical transmission of coated samples increases from 91.4 to 93% for 90SiO2–10ZrO2 coatings, and increases from 80% for eroded samples (Mp = 200 g) coated with SiO2–ZrO2 films up to 91% while micro-hardness is greatly improved from 10.17 GPa for the raw material to 17.62 GPa for 70SiO2–30ZrO2 coated sample.