Fabrication and characterization of the microporous and nanoporous anodic oxidations of titanium-silver alloys

The purpose of this study was to fabricate and evaluate the morphological structure of microporous anodic oxidation (MAO) or nanoporous anodic oxidation (NAO) treated titanium-silver (Ti-Ag) alloys. The Ti-Ag alloys were arc melted, homogenized, and quenched in water at room temperature. The MAO treatment was performed using β-glycerol phosphate (β-GP) and calcium acetate (CA) solution; the NAO treatment was performed using hydrofluoric acid (HF) solution or ammonium fluoride (NH4F) solution. Surface-treated Ti-Ag alloys were compared to commercially pure titanium (cp Ti). The surface morphology and phase state were analyzed by field emission scanning electron microscopy (FE-SEM) and high resolution X-ray diffraction (HR-XRD). Both the MAO treated cp Ti and Ti-Ag alloy samples presented a regular oxide layer with a diameter of approximately 1-3 μm. Morphology was clearly visible on NAO Ti-Ag alloy samples treated with NH₄F solution, with a diameter of roughly 100 nm. However, HF solution treated NAO Ti-Ag alloy samples appeared to be sparsely- and irregularly-shaped, ranging in size from a few nanometers to 100 nm. From the HR-XRD analysis, amorphous TiO₂, Ti, and Ti-Ag phases were observed in the MAO and NAO treated Ti-Ag alloys. The MAO and NAO treated cp Ti samples only showed peaks associated with Ti. The surface characteristics of Ti-Ag alloys may possibly influence cell viability.