The French SON68 Glass Vapor Hydration under Different Atmospheres

We investigated the role of pH in the vapor hydration at 175 oC of the French SON68 glass using controlled atmospheres. Hence, experiments were conducted under ammonia and hydrogen sulfide to respectively simulate high and low pH conditions. Results were compared with those obtained under air. Glass hydration and surface analysis were conducted by FTIR, SEM and μ-Raman spectrometry. The glass hydration is ten times higher under NH3 than under H2S. Under ammonia the main corrosion products were analcime and a smectite, and incidentally calcite, apatite and tobermorite while under hydrogen sulfide only a gel-like phase was identified. The precipitation of silica-consuming secondary phases at high pH involves high hydration rates under ammonia atmosphere.