Microscale Surface Patterning of Zirconia by Femtosecond Pulsed Laser Irradiation

Irradiation of yttria-stabilized zirconia (YSZ) was performed by a femtosecond pulsed laser to investigate the feasibility of V-shaped groove microstructure fabrication. Firstly, fundamental characteristics of microgroove fabrication was investigated by varying scanning speed of laser and number of scans. Higher scanning speed resulted in a smooth surface without any debris adhesion. By increasing number of scans, the cross-sectional profile of the microgroove became a well-defined V shape, and the taper angle of the V-shaped groove can be precisely controlled by laser scanning speed. Moreover, the laser-induced phase transformation of YSZ was characterized, and it was found that the monoclinic ratio after irradiation decreased in comparison with original YSZ surface, indicating improved strength and toughness. TEM cross-sectional observation of the microgrooves was performed and tetragonal phase was detected independent of locations. Finally, micro pyramid structures were created on the YSZ surface by perpendicularly crossing the laser scan directions. The resulting surface showed a drastic change in surface wettability. These findings demonstrated the possibility of generating precise complex microstructures on YSZ surface with high functionality and low subsurface damage, presenting great potential of wide applications in industry.