Role of micro-dimple array geometry on the biological and tribological performance of Ti6Al4V for biomedical applications

Mahboubeh Sadeghi, Mahshid Kharaziha, Hamidreza Salimijazi, Ehsan Tabesh

The purpose of this study was to employ surface texturing, using CO2 pulsing laser, to create micro-dimple arrays and study the role of diverse geometries of micro-dimples on the physical, biological and tribological responses of Ti6Al4V. Scanning electron microscopy and X-ray diffraction were applied to study the structural and chemical composition of surface treated samples, respectively. Furthermore, the effects of laser treatment on the surface hydrophilicity, topography and hardness of samples were investigated using water contact angle measurement, surface roughness tester and micro-hardness tester. Results confirmed the noticeable role of scan rate (0.5, 1, 5 and 10 mm/s) on the morphology of micro-dimples, the chemical structure and hardness of the samples. In this respect, increasing the scan rate of laser irradiation from 0.5 mm/s to 10 mm/s resulted in the formation of acicular α-Ti around micro-dimples with various thicknesses. Moreover, micro-hardness of Ti6Al4V greatly improved to 635 ± 21 HV, when the scan rate enhanced to 5 mm/s. In addition, the effect of surface texturing on the attachment, proliferation and spreading of MG63 cells were investigated. Results confirmed that cell proliferation was significantly improved on the textured Ti6Al4V. Tribological characterization revealed that poor tribological properties of TiO2 layers on Ti6Al4V could be meaningfully modified using laser texturing, depending on the geometries of micro-dimples. Additionally, noticeably reduction of friction was obtained on the textured samples. In summary, laser texturing could be effectively applied to simultaneously enhance the tribological and biological performances of Ti6Al4V alloy for biomedical applications.