Hydrothermally treated cesium borosilicate glass with enhanced crack initiation resistance and indent volume recovery

Oxide glasses are essential in modern technologies, but their inherent brittleness and sensitivity to surface flaws significantly limit performances, emphasizing the necessity to enhance their mechanical properties. Recent work has found that a hydrated cesium aluminoborate glass shows a very high crack initiation resistance (∼400 N), along with the ability to recover the volume of an induced indent upon storage in a humid atmosphere. This is related to the glass’ low chemical durability, as the hydration effect on glass mechanics drastically diminishes when substituting the cesium modifier with other alkali modifiers. In this work, we study the effect of hydrothermal treatment on the structure and mechanical properties of a cesium borosilicate glass, i.e., a glass with higher chemical durability than the aluminoborate composition. We find that higher rigidity of the silica-containing glass necessitates both higher temperature and relative humidity of the hydrothermal treatment to induce significant property changes. Still, hydrothermal treatment causes both an increase in crack initiation resistance and a decrease in induced indent volumes, while maintaining the sample’s optical transparency. These findings therefore shed light on the potential positive effects of using hydrothermal treatment to modify the mechanical properties of oxide glass surfaces.