Effect of sandblasting on the surface roughness and residual stress of 3Y-TZP (zirconia)

A defined surface roughness is important for the adhesive bonding of veneering ceramic to zirconia frameworks. Thus, we investigated the effects that sandblasting has upon the surface roughness and residual stress of zirconia. So as to achieve well-defined blasting parameters and also generate highly reproducible results; a custom-made, automated sandblasting machine was constructed (based on a 3D-printer construction kit). Thirty-two samples (measuring 30 mm x 35 mm x0.2 mm) were cut from densely sintered 3Y-TZP blanks and then ground with a 45 mu m grinding disc. After undergoing regeneration firing, the samples were sandblasted with varying working parameters: blasting angle (45 degrees, 60 degrees and 90 degrees); blasting pressure (2 bar, 4 bar and 6 bar); and working distance (0.5 cm, 1.0 cm and 1.5 cm). The sandblasting path was chosen so as to create samples with an even surface roughness. Changes in blasting pressure resulted in the greatest changes in the surface roughness, the highest surface roughness values were achieved with sandblastings perpendicular to the sample surface. Furthermore, a correlation was found between the mean surface roughness and the residual stress.