Formation and chemical durability of Na-Si-O-N and Na-Al-Si-O-N oxynitride glasses

Abstract

Using oxide glasses of compositions xNa2O·(100-x) SiO2(x = 20-50 in mol) and 40Na2O·(60-y)SiO2· yAl2O3 (y = 5, 10 in mol) as base glass, Na-Si-O-N and Na-Al-Si-O-N oxynitride glasses were prepared by melting powder mixture of oxide glass and Si3N4 or AIN, and the effects of the base oxide glass composition on the glass forming ability, the amount of incorporated nitrogen and the chemical durability of oxynitride glasses were studied. It was found in Na-Si-O-N glasses that the lower Na2O content is favorable for the formation of nitrided glass, giving larger glass forming regions. Retained nitrogen content decreased with increasing Na2O content in Na-Si-O-N glasses and with increasing Al2O3 content in Na-Al-Si-O-N glasses. Chemical durability of Na-Si-O-N glass increased with increasing of nitrogen content for any Na2O content of the base glass. For Na-Al-Si-O-N system, however, nitrogen incorporation increased or decreased chemical durability, depending on the Al2O3 content and nitrogen content in the glasses or had no appreciable effect.