Surface roughness and EDS characterization of a Y-TZP dental ceramic treated with the CoJet™ Sand.

Objectives: (1) To determine the surface roughness and material loss of a Y-TZP ceramic before and after tribochemical grit blasting and (2) to characterize the changes in elemental surface composition and the phase transformations after tribochemical treatment.

Methods: Machined bar shaped specimens (Zeno, Wieland) were subdivided into three groups. After grit blasting for 10, 20 and 30s respectively, half of the specimens of each group were ultrasonically cleaned in ethanol for 10min. The other half was rinsed with a water spray. Surface roughness was measured using an electro-mechanical profilometer. The elemental composition of the samples was obtained by energy dispersive X-ray spectroscopy (EDS). X-ray diffraction (XRD) was used for phase transformations determination.

Results: The median Ra increased significantly from 0.24 to 0.32-0.38μm after grit blasting. Augmentations were also noted for R(max), R(v) and R(p). The highest roughness parameters were, obtained for water sprayed specimens and samples abraded for 30s. Loss of material ranged between 1 and 3μm for 30s grit blasting. Tetragonal and cubic phases were identified in 'as machined' specimens. Grit blasting resulted in domain switching and lattice deformations. The elemental composition comprised Si and Al. The duration of grit blasting did not significantly, influence the atomic percentages of Si or Al. Significantly lower values for both Si and Al were noted, after ultrasonic cleaning.

Significance: Grit blasting with CoJet™ Sand resulted in an increase of surface roughness, a removal of maximum 3μm of material and coated the surface with submicron silica and alumina particles.