Effect of Surface Energy on the Mechanical Strength of a High‐Silica Glass

The mechanical strength of high‐silica glass was measured in various organic liquids and in water. The extent of the surface‐energy reduction of glass was also estimated from the swelling or the expansion of porous glass, immersed in liquids, by measuring the stress in the core of a partially leached glass. The stress, normalized to the value in water, showed a good correlation with the heat of immersion, which is a measure of the surface‐energy reduction. Mechanical strength and the stress due to swelling showed a reasonable correlation, suggesting that the strength variation in various liquids is due to the surface‐energy variation and the accompanying force which caused the swelling.