A consolidated article with a surrounding the glass surfaces - compressive-stress layer and method for its production

摘要

To strengthen a glass article formed from a lithium-silicate or lithium-aluminium-silicate glass, the glass surface is contacted with a source of exchangeable monovalent ions larger than lithium ions at an elevated temperature but below the glass strain point to thermochemically exchange lithium ions from the glass with the larger ions to form a surface layer in which a portion of the lithium ions have been replaced by the larger monovalent ions, the ion exchange being continued for a sufficient time to impart increased abraded strength to the glass article. A molten sodium salt is the preferred source of the larger monovalent ions. A large number of examples of compositions are given. Specifications 454,448, 786,951, 917,388, 966,733 and 966,734 and U.S.A. Specification 2,075,446 are referred to.