Papers by Keyword: Alkali-Heat Treatment

Abstract: The deposition of hydroxyapatite has been applied to enhance the bioactivity of Ti-6Al-4V as implant materials. However, the hydroxyapatite has poor adhesion strength to a substrate which can lead to coating delamination. In this study, we combine the alkali-heat treatment of Ti-6Al-4V and the electrophoretic coating process of the hydroxyapatite to obtain the strong mechanical interlocking. The Ti-6Al-4V implants were etched in Kroll solution before the alkali-treatment was performed using 5M and 10M NaOH at 24, 48 and 72 hours and thermally stabilized at 600°C and 800°C for 1 hour using a stepwise heating rate of 5°C per min. The electrophoretic deposition process conducted at a constant cell voltage of 20 V for 10 min at room temperature and then sintered in a vacuum furnace at 800°C. The result shows that the feather-like structure on Ti-6Al-4V surface was created by incorporating sodium ions onto the Ti-6Al-4V surface during alkali-treatment using NaOH 5M for 48h and stabilized using heat treatment at 600°C where the hydroxyapatite filled the interspaces to become integrated with the feather-like structure so that the osseointegration can occur as the bioactivity increased.

Abstract: Porous titanium with relative density from 0.4 to 0.64 was prepared by powder metallurgy. The porous structures were examined by scanning electron microscopy and phase constituents were analysed by X-ray diffraction. Mechanical properties of the porous titanium were investigated using a compressive test. To enhance the bioactivity of the alloy surface, alkali-heat treatment was used to modify the surface. Results indicate that the elastic modulus and plateau stress of the porous titanium samples both as-sintered and alkali and heat treatment decrease with decreasing relative density. And the relationship between relative yield stress and elastic modulus with relative density of porous titanium after alkali and heat treatment are agreement with that of as-sintered porous titanium. After alkali-heat treatment, a bioactive Na2Ti5O11 layer formed on the surface of the pre-treated porous titanium. A reduction in the number and severity of this bioactive deposition was observed with the decrease in relative density of porous titanium because of the increasing surface area. In a word, The mechanical properties of the porous titanium can be tailored to match those of human bone, therefore, these bioactive porous titanium have the potential to be a bioactive implant material.

Abstract: Titanium and some of its alloys are widely used as load-bearing implant materials. In particular, titanium-zirconium (Ti-Zr) alloys have a high potential for biomedical applications due to the excellent biocompatibility of both Ti and Zr. Nevertheless, the surfaces of the Ti-Zr alloys need to be modified to provide the implant material’s bioactivity. In the present study, an alkali-heat (AH) treatment process followed by the soaking in simulated body fluid (SBF) was attempted for the preparation of calcium phosphate (CaP) coatings on the surface of the TiZr alloy. Phase transformation, surface morphology, and interfacial microstructure were investigated using scanning electron microscope (SEM) with an energy-dispersive electron probe X-ray analyser (EDS). The results indicate that the AH treatment produced a nano-porous bioactive sodium titanate / zirconate hydrogel surface layer which induced the deposition of a Ca-P layer during soaking in the SBF. This Ca-P layer on the TiZr alloy surface can be expected to bond to the surrounding bones directly after implantation.

Abstract: In this study, alkali-heat treatment in NaOH solution and heat treatment, which could form amorphous sodium titanate on nanophase titania ceramics surface by conditioning the process, was employed to modify the structure and bioactivity of biomedical titania ceramics. After the nanophase titania ceramics was subjected to alkali-heat treatment, thin film X-ray diffraction and scanning electron microscopy results showed the titania ceramics surfaces were covered by porous sodium titanate. In fast calacification solution (FCS), the alkali-heat treated titania ceramics could induce bonelike apatite formation on its surface. Our results showed that induction of apatite-forming ability on titania ceramics could be attained by alkali-heat treatment. So it was an effective way to prepare bioactive titania ceramics by combining sintering and alkali-heat treatment.