Chlorine treatment of nitrided porous glass

Abstract

Nitrided reconstructed 96 % SiO2 glasses prepared from ammonia-treated porous glass have a tendeney to reboil on heating to the high temperatures required for lampworking. This problem can be eliminated by subjecting the nitrided porous glass to chlorine at elevated temperatures prior to pore closure. Infrared measurements of the final glasses show that =NH groups are absent in the chlorine-treated glasses. Possible reactions that account for the removal of hydrogens from amide groups are presented. The role of subjecting the nitrided porous glass to a hot acid wash is also discussed.