Wear properties of micro arc oxidized and hydrothermally treated Ti6Al4V alloy in simulated body fluid

Hydroxyapatite (HA) has a strong ability to form a direct chemical bond with the hard tissues. It is also synthesized on Ti6Al4V alloy using micro arc oxidation (MAO) followed by hydrothermal treatment (HT). In this study, Ca and P containing titania coated surfaces were achieved from the MAO coating process which was carried out at 450 V for 5 minutes and at a frequency of 300 Hz in a calcium acetate monohydrate and β-glycerophosphate aqueous solution. The substrates coated with TiO2 were hydrothermally treated inside a NaOH solution which had the pH value of 11.0–11.5 at 160 °C, 190 °C and 220 °C for 5 h and 10 h in a pressure vessel. Microstructure and phase components of the coatings were characterized using scanning electron microscope (SEM) and X-Ray diffraction (XRD) before and after micro arc oxidation and hydrothermal treatment. Each untreated, Ca and P containing TiO2 coated and HA coated specimens were subjected to pin on disk wear tests inside simulated body fluid (SBF) at 37 °C. It was observed that after HT, rough and porous bioactive HA crystals were formed on the surface. HA/TiO2 film layer formed with MAO plus HT improved the wear properties of Ti6Al4V. By this way, a surface which has a good wear resistance and bone bonding ability was achieved.