A comparative investigation on micro-channel by using direct laser ablation and liquid-assisted laser ablation on zirconia

In this work, direct laser ablation (DLA), liquid-assisted laser ablation in water (LALA-W) and in ethanol (LALAE) is applied to fabricate single micro-channels on the zirconia ceramic by using a picosecond laser. To assess the machining ability of them, micro-channels fabricated are characterized and compared the differences in morphology, geometric profile, chemical and phase composition. The morphological results indicate that both LALA-E and DLA can fabricate microchannel with obvious recast layer and cracks, and LALA-W can fabricate microchannel with a porous surface, and almost no recast layer and cracks. The results of geometric characteristics show that LALA-W can fabricated micro-channels with "U" shape profile with 52.74% enhancement in depth compared to that "V" shape by DLA and LALA-E. The XPS results demonstrate that LALA-W can exhibit the smallest oxygen vacancies with 50.01% than that of LDA 53.81% and LALA-E 54.56%. For XRD results, after machining by all three processes, the zirconia ceramic undergoes the tetragonal -> monoclinic phase transformation, resulting in an increase in monoclinic phase. While LALA-W exhibits the smallest increase in monoclinic phase from 9.9% to 12.7%, and has the most tetragonal phase content of 58.8%.