METHODS FOR REDUCING ZIRCONIA DEFECTS IN GLASS SHEETS

摘要

Methods are disclosed for treating zircon-containing forming structures, e.g., zircon isopipes, with one or more treatment glass compositions in which defect-causing reactions between the zircon of the forming structure and molten glass are suppressed at the delivery temperature of the treatment glass. The treatment compositions can be used during start-up of a forming structure, between runs of the same production glass on a given forming structure, and/or when transitioning between runs of two production glasses on a given forming structure. The treatment compositions can be used with production glasses that are ion-exchangeable.

主权项

1. A treatment process for treating a forming structure in preparation for producing glass sheets from molten glass having a production composition, said forming structure having an outer surface at least a part of which is composed of zircon and comes into contact with the molten glass during use of the forming structure, said treatment process comprising:
(A) melting batch materials to produce molten glass having a treatment composition, said batch materials comprising silica; and (B) delivering the molten glass having the treatment composition to the forming structure at a delivery temperature Tdelivery/treatment;wherein:
at Tdelivery/treatment, the treatment composition promotes the reaction:
ZrO2+SiO2→ZrSiO4; and (ii) the treatment process reduces the level of zirconia defects in glass sheets produced from the production composition using the forming structure.