Effect of the Hydrothermal Heat Treatment Conditions of Titanium Substrates on the Bio-Mimetically Grown “Bone-Like” Apatite Coatings
Hydrothermal surface modifications of the titanium specimens were performed (i) at 200 °C under 1.5 MPa pressure, and (ii) at 230 °C under 2.5 MPa pressure. To see the effect of an ion implantation, two different aqueous hydrothermal environments were selected: (i) de-ionized water and (ii) calcium containing de-ionized water. Hydrothermally treated titanium surfaces were analyzed by X-ray photoelectron spectroscopy (XPS) and found to become rich with Ca when Cacontaining hydrothermal environment was used. The surface-modified titanium specimens were then kept immersed in 1.5X simulated body fluid (SBF) for 1, 2, 3 and 4 weeks. The biomimetically formed coatings were characterized using scanning electron microscopy (SEM) and Xray diffractometer (XRD). Crack formations and, consequently, severe peelings were observed after drying for all the coatings on the substrates that were treated hydrothermally using only de-ionized water. The Ca implanted titanium surfaces, on the contrary, were able to develop crack-free and quite cohesive coatings. Up to two weeks of immersion and after drying, no-cracks were observed in the coatings when the substrates were treated at higher temperature and under higher pressure (230 °C and 2.5 MPa for the present investigation).
Pietro VINCENZINI, Ralf RIEDEL, Alexander G. MERZHANOV and Chang-Chun GE
D. Teker et al., "Effect of the Hydrothermal Heat Treatment Conditions of Titanium Substrates on the Bio-Mimetically Grown “Bone-Like” Apatite Coatings", Advances in Science and Technology, Vol. 63, pp. 402-407, 2010