Surface hardness of sheet glass untreated and treated with vapours of metal chlorides

JSGT 1959 V43 T438-T450

The difference between the properties of the surface layers of alkali–lime–silica glasses untreated and treated with vapours of various metal chlorides can be shown by surface hardness measurements. Using metals with ionic diameters less than 1 Å, the hardness of the surface is about twice that at a depth of 0·5–0·6 µ from the surface, confirming the penetration of the ions from the vapours into the gel-layer. By treating the glass with the vapours of chlorides containing metals with ionic radii exceeding 1 Å, the surface hardness remains unchanged. It can be assumed therefore that the surface structure of the outer layer of the glass is less dense than that of the deeper regions.

G. Koranyi