Characteristics of ceramic-like coatings obtained by plasma electrolyte oxidation on different Ti alloys

Plasma electrolyte oxidation was used to modify the surface of different Ti alloys: c.p. Ti (alpha hcp structure), Ti-15Nb (alpha ' + beta structure) and Ti-33Nb-33Zr (stable beta cubic structure) and the influence of elements and microstructure in the TiO2-based ceramic layer formed as well as the surface properties was analyzed. The XRD patterns confirmed the presence of TiO2 (anatase and rutile) in the c.p. Ti. For Ti-15Nb (wt.%) indicated the presence the same oxides also of pentoxide niobium (Nb2O5). For Ti-33Nb-33Zr (wt.%) indicated just the presence of rutile as the stable oxide one at room temperature and dioxide zirconium (ZrO2). In addition, the formation of calcium carbonate CaCO3 and calcium phosphate Ca-3(PO4)(2) was detected in all 3 materials. The ceramic-like layer was more homogeneous for c.p. Ti and Ti-15Nb and more irregular hole like-pores for Ti-33Nb-33Zr. Bioactive ions used were detected in all alloys and the roughness for Ti-15Nb was higher compared to c.p. Ti. and Ti-33Nb-33Zr. The contact angle for the three samples was higher than 100 degrees.