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

Abstract

Plasma electrolyte oxidation was used to modify the surface of different Ti alloys: c.p. Ti (α hcp structure), Ti–15Nb (α′+β structure) and Ti–33Nb–33Zr (stable β 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 Ca3(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°.