Nanosecond-laser patterning of 3Y-TZP: Damage and microstructural changes

The aim of this study is to characterize in detail the microstructural changes and collateral damage induced by direct laser patterning on the surface of dental-grade zirconia (3Y-TZP) employing an interference setup with the 532 and 355 nm harmonics of a Nd:YAG laser (pulse duration of 10 ns). Laser-material interaction mainly results in thermal effects for both wavelengths studied. Upon laser irradiation the material locally melts producing pattern and establishing a steep thermal gradient on the surface. This generates a similar to 1 mu m thick heat affected zone where microcracking, directional recrystallization, phase transformation (from tetragonal to monoclinic, t -> m) and texturization (ferroelastic domain switching) take place. In addition, surface coloration results from the activation of F-centers as a consequence of high energy radiation exposure. No chemical segregation or diffusion was detected. All these microstructural changes should be taken into account to ensure integrity and long-term reliability of the zirconia components. (C) 2017 Elsevier Ltd. All rights reserved.