Preparation and characterization of a novel Si-incorporated ceramic film on pure titanium by plasma electrolytic oxidation

A Si-incorporated bioactive ceramic film was prepared on pure titanium by plasma electrolytic oxidation (PEO) in a new bath containing Ca²⁺, H₂PO₄⁻ and SiO₃²⁻. The film was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscope (XPS). The apatite-induced ability of PEO film was evaluated by soaking in a simulated body fluid (SBF) for various periods. The results showed that Si-incorporated PEO film present a porous microstructure, the pore size is around 1–5 μm. The film mainly consists of anatase and rutile and a small amount of CaHPO₄ and CaO, besides, bioactive compounds such as CaSiO₃ and SiO₂, also exist in the Si-incorporated PEO film. After immersion in SBF for 28 days, not only the surface layer but also the pores inside the Si-incorporated PEO film were completely filled by apatite crystals, whereas on the surface of a benchmark PEO film free of Si just present small piles of apatite crystals. Silicon incorporated into the PEO film provided more heterogeneous nucleation sites for apatite deposition and hence increased remarkably bioactivity of the PEO film.