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

Abstract

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. ~. 1. µm 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.