Chemical Stability of Na2 O  ‐ ZrO2 ‐ Al2 O 3 ‐ SiO2 Glasses in Sodium, Sodium Polysulfides, and Sulfur

Abstract

Glass compositions from the Na2O‐ZrO2‐Al2O3‐SiO2 system were tested for chemical stability by exposure at 400°C for 1000h in Na, S, Na2S4 and Na2S3 . Weight‐change data and results of microscopic analysis of glass samples after testing, taken together, indicated that the composition containing about 42 normalmole percent false(normalm/normalofalse)Na2O , 8 normalm/o Al2O3 , and 5 normalm/o ZrO2 (balance SiO2 ) had a chemical stability in all four media comparable to that of β″‐alumina. With this type of glass in all the media containing sulfur, just a slight increase in alumina (to 11 m/o) and zirconia (to 8 m/o) produced surface and internal cracks. Although the chemical stability data for the above glass are encouraging, cell tests are necessary to confirm these experiments.