Investigation of silicic acid saturation and gel formation during ISG leaching: 180 days duration reaction at 90 °C

Abstract

Currently, borosilicate glasses are utilised to immobilise highly radioactive waste. They are durable materials; however, they corrode in aqueous solutions, resulting in silica-rich alteration layers. This study employed the nuclear waste leaching tests (MCC-1, MCC-3) on International Simple Glass (ISG) samples. The corrosion rate in pure water and saturated water with respect to ISG corrosion products was investigated at an initial pH of 6.3 and a reaction temperature of 90 °C. For 3, 7, 14, 28, 90, and 180 days, batch experimental models with extremely high and very low glass surface area to volume (S/V) ratios were examined. The results showed that early saturation in the higher S/V system resulted in a ten order magnitude reduced corrosion rate compared to the lower S/V system. This emphasises the significance of saturation in achieving a reduced corrosion rate. This research proved the significant influence of the solution’s chemistry on the glass corrosion rate via pH and other chemical parameters.

Impact of Chemical Corrosion on Mechanical Properties of Boroaluminosilicate Pharmaceutical Glasses

“…A large number of studies have shown that an alteration layer (AL) is often created on a glass surface in the long-term corrosion process, and the formation of the alteration layer will slow down the further corrosion process [21,22]. The microstructure of the alteration layer is extremely complex and very different from the original glass, such as "hydrated glass" or "mutual diffusion layer", amorphous layer rich in silica, precipitate layer formed by secondary minerals and so on [23][24][25][26]. The complex microstructure of the alteration layer has a great influence on the mechanical properties of the glass surface [27,28].…”