Enhancing the adhesion strength of tantalum oxide ceramic thin film coating on biomedical Ti–6Al–4V alloy by thermal surface treatment

In this study, Titanium alloy (Ti–6Al–4V) substrate was coated with 4 μm tantalum oxide (Ta–O) ceramic layers using physical vapor deposition magnetron sputtering (PVDMS). The coated sample surfaces were heat treated at 300, 400 and 500 °C in a box furnace to enhance the adhesion strength. Field Emission Scanning Electron Microscopy (FESEM) together with energy dispersive X-ray spectroscopy (EDX), X-ray diffraction analysis (XRD) and Vickers microhardness testing was used to distinguish the Ta–O coatings in terms of morphology, surface elements, structure and surface hardness, and to compare untreated and hardened sample conditions. The effect of heat treatment on adhesion was tested with scratch test equipment. The coating thin film adhesion strength improved from 713 to 1907 mN throughout the thermal surface treatment duration. The effect of thermal treatment on surface hardness was examined, and evidently, the surface hardness increased from 446.24 to 535.5 HV on account of the surface treatment at 500 °C.