Problems Associated with the Melting of Oxynitride Glasses

Abstract

Carbon dioxide from carbonate batch materials oxidizes Si 3 N 4 , causing N 2 loss from oxynitride glass melts. Lithia is the only alkali which is compatible with oxynitride melts; all other alkalis are reduced and volatilized during melting. A high partial pressure of oxygen (P 02 over oxynitride melts oxidizes Si 3 N 4 , leading to N 2 loss, whereas a low P o2 , results in vaporization of SiO.