Mechanical Properties and Tribological Behavior of Cu2O Nanosheets Deposited on TiO2 Nanotubes for Anti-Corrosion and Anti-Wear Implant Applications

Successive ionic layer adsorption reaction (SILAR) was used to deposit Cu2O nanosheets on anodized TiO2 nanotubes at different deposition cycles (4, 8, 15, and 20). Compared to the bare TiO2 nanotubes, these coatings were investigated for their tribological behavior (friction, wear and energy loss), scanning and transmission electron microscopy (SEM, TEM), X-ray Diffraction (XRD) was used to characterize Cu2O/TiO2 coatings to study the effect of number of cycles on the morphological and structural properties of the samples; these characteristics engage in determining the wear mechanisms. The assessment of the coating’s adhesion was determined by the obtained critical loads from the scratch test; the 15 cycles Cu2O/TiO2 exhibited higher critical loads, which corresponds to improved adhesion. This sample also showed a low wear volume of 7.5 × 106 µm3 compared to other samples but higher energy loss due to the low shear strength of copper oxide. The friction coefficient, however, decreased from 0.7 for bare TiO2 nanotubes to 0.48 for 20 cycles Cu2O/TiO2 coatings at higher loads, which proves the wear resistance enhancement. Since these coatings will be manufactured for orthopedic and dental implant applications, the corrosion resistance was tested, and the 15 cycles Cu2O-NPs/TiO2-NTs where these coatings exhibited the most favorable combination of a low corrosion current density (1.9 × 10−4 A/cm2) and a noble corrosion potential (−0.3 V/SCE); furthermore, there was a polarization resistance of 2.4 × 104 Ω·cm2 and a protection efficiency of 96.7%, indicating significantly enhanced corrosion resistance as opposed to the other samples.