Wettability and frictional properties on zirconia surfaces irradiated by femtosecond laser

This study aimed to explore the wettability and tribological performance of zirconia surface by laser irradiating. To investigate the effect of laser parameters, zirconia samples were divided into two groups according to laser power and scanning pitch. The surfaces were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and goniometer. Microcracks were observed from SEM in the laser-irradiated area. The XRD results in turn indicated that the tetragonal -> monoclinic (t -> m) phase transformation led to microcracks formation. The contact angles (CAs) results demonstrated that the effect of laser powers on wettability was more than that of scanning pitch. With moderate laser power, it is possible to induce micro/nano morphology with best wettability. Hardness tests and friction tests were further performed to investigate the effect of laser irradiation on mechanical properties. The results indicated that the hardness of laser-irradiated showed a slightly increase, expect for the case of the percentage of m phase exceed 50 %. Meanwhile, laser irradiation can slightly reduce the coefficient of friction (COF) of dry friction and increase the COF of wet friction. For wet friction, laser-irradiated microstructure can effectively enhance the adhesion of bone to zirconia. This work may offer a simple method to produce surfaces with controlled wettability and phase transformation by selecting appropriate laser parameters to promote the adhesion of bone to zirconia.