Comparative Single-Point Diamond Scratching Behavior of a Cordierite Glass and Glass-Ceramic

A comparative study was conducted of the single-point diamond scratching response of a cordierite glass and glass-ceramic. For the glass, deformation and material removal occurred by viscous flow at the lowest values of load, viscous flow combined with crack formation adjacent to the contact area over the intermediate load range, and extensive spoiling at the highest values of load. The density of the spalls and spall size were found to be proportional and inversely proportional to perpendicular scratching load, respectively. The glass-ceramic exhibited plastic flow and abrasive wear at loads as low as could be reliably measured, the particle size of the debris being of the order of the grain size. At the highest ranges of load, the glass-ceramic exhibited material removal by spall formation with a spall size proportional to load. At the lower ranges of load, the widths of the scratch for the glass and glass-ceramic were comparable. However, at the highest values of load tne size of the spall of the glass-ceramic was significantly less than the size of the spall in the glass.