Ultrasonic abrasion of quartz crystals

In the present work, we investigate the wear mechanisms associated with the ultrasonic abrasion of quartz. Ultrasonic abrasion was carried out in X-, Y-, Z- and AT-cut plates of natural quartz and Z-cut plates of synthetic quartz. The counter bodies, square and cylindrical, were fabricated from stainless steel. The abrasive slurry was made from boron carbide with mean grain size of 25 μm and water. In the case of synthetic crystals, silicon carbide with mean grain size ranging from 6 to 50 μm was adopted. The abraded surfaces were characterized by scanning electron microscopy (SEM) and surface roughness profilometry. It was found that the wear rate was affected by the crystallographic orientation of quartz specimens. The grain size of abrasive particles affected both wear rate and surface roughness. Brittle microcracking was the main wear mechanism involved in the removal of material, which was due to hammering and impact actions of abrasive particles on the work piece material. It was observed that wear rate was inversely proportional to the product K1c3/2H1/2. For this purpose, hardness and fracture toughness of quartz crystals were determined by using the quasi-static indentation method. A secondary wear mechanism went into operation when abrasive grits larger than 15 μm were used. It was found that this same mechanism could be predicted by the evolution of skewness and kurtosis coefficients of the surface topography.