Effect of water-based electrolyte on surface, mechanical and tribological properties of ZrO2 nanotube arrays produced on zirconium

Abstract

In this work, highly ordered ZrO2 nanotube arrays were fabricated on commercial pure Zr substrates through anodic oxidation in the water-based electrolyte at various voltages (30 V, 40 V and 50 V) for 1 h. The monoclinic- and tetragonal-ZrO2 phases were obtained on ZrO2 nanotubes through anodic oxidation. 13 vibration modes have been observed for the samples grown at low voltages (30 V and 40 V), which are assigned to monoclinic symmetry (7Ag + 6Bg), while-with the increasing growth voltage, the dominant phonon peak intensities associated with the monoclinic symmetry 6 times are decreased, and Eg (268 and 645 cm - 1) mode corresponding to tetragonal symmetry is observed. The nanotube array surfaces exhibited hydrophilic and super-hydrophilic behavior compared to the bare Zr surface. The elastic modulus values of ZrO2 nanotube surfaces (14.41 GPa) were highly similar to those of bone structure (10-30 GPa) compared to bare Zr substrate (120.5 GPa). Moreover, hardness values of ZrO2 nanotube surfaces were measured between similar to 76.1 MPa and similar to 283.0 MPa. The critical load values required to separate the nanotubes from the metal surface were measured between similar to 1.6 N and similar to 26.3 N. The wear resistance of the ZrO2 nanotube arrays was improved compared to that of plain Zr substrate.