Glass Strengthening Using Ormosil Polymeric Coatings

Abstract

Ormosil polymeric coatings comprised of an epoxy resin, an amine hardener and a silane have been applied to glass samples containing large, controlled defects introduced by Vicker's indentation. The coatings can completely overcome these controlled defects. The strengthening effect is due to penetration of the defects by the coatings. Therefore, the reactions between the components of these hybrid materials and the glass substrate are of crucial importance in determining both the degree of strengthening that is achieved and the hydrolytic durability of the coatings. The maximum strengthening effect of these ormosil polymeric coatings is obtained when 25% of the active hydrogen is supplied by the silane (7.2 wt% silane). More than 7.2 wt% silane reduces coating cohesion and thus gives a reduced strengthening effect. Studies on silane primed systems show that both good coating adhesion and cohesion are required for significant strengthening. Coatings with good adhesion also have greater hydrolytic durability.