DEGRADATION OF THE STRENGTH OF GLASS AFTER LIGHT CONTACT WITH OTHER MATERIALS

Damage to the surface of soda-lime glass arising from contact with oth er materials was evaluated by comparing the strength of etched glass r ods before and after contact. Contact with carbon is much less damagin g than contact with other materials. Contact with both titanium and me erschaum (hydrated magnesium silicate) produced a significant decrease in the strength of the etched glass, even though the meerschaum was a s soft as the carbon compacts. Sintered titanium specimens caused even more damage to the glass, probably because of the effect of hard oxid e particles introduced during sintering. It is concluded that contact damage arises from plastic indentation of the glass surface on the mic roscale by hard particles or phases in the surface layers of the conta ct material; the bulk hardness of the contact material has an effect i n producing damage through the transmission of force in the hard parti cle-glass surface interaction.