Table 4.

Analysis of the surface oxide film on various metallic biomaterials.

Biomaterial	Surface Oxides	Surface Analysis
CP-Ti	Ti0, Ti2+, Ti3+, Ti4+	Ti2+ oxide thermodynamically less favourable than Ti3+ formation at the surface. Ti2+ and Ti3+ oxidation process proceeds to the uppermost part of the surface film and Ti4+ is observed on the surface outer most layer
Ti–6Al–4V	TiO2	Surface consists of small amount of Al2O3, hydroxyl groups and bound water. The alloying element V is not detected
Ni–Ti	TiO2-based oxide	Minimal amounts of Ni in both oxide and metal states
Ti–56Ni	TiO2	Very low concentrations of metallic Ni, NiO, hydroxyl groups and bound water
Ti–Zr	Ti and Zr oxides	Ti and Zr are uniformly distributed along the depth direction. The thickness of the oxide film increases with increase in Zr content
316L stainless steel	Oxides of Fe, Cr, Ni, Mo and Mn	Thickness ~3.6 nm. The surface film contains a large amount of (OH)–, that is, it is either hydrate or oxyhydroxide. The outer surface layer is enriched with Fe, beneath is it enriched with Ni, Mo and Mn
Co–36.7Cr–4.6Mo alloy	Oxides of Co and Cr, without Mo	Thickness ~2.5 nm. The surface film contains a large amount of (OH)–, that is, it is either hydrate or oxyhydroxide. Cr and Mo are distributed more in the inner layer of the film