Bioactive surface modification of Ti-29Nb-13Ta-4.6Zr alloy through alkali solution treatments.

Tantalum as a Novel Biomaterial for Bone Implant: A Literature Review

The Ministry of Education, Culture, Sports, Science and Technology of Japan started the Priority Assistance for the Formation of Worldwide Renowned Centers of Research – Global COE Program. This program is based on the competitive principle where a third party evaluation decides which program to support and to give priority support to the formation of world-class centers of research. Our program Center of Excellence for Advanced Structural and Functional Materials Design was selected as one of 13 programs in the field of Chemistry and Materials Science. This center is composed of two materials-related Departments in the Graduate School of Engineering: Materials and Manufacturing Science and Adaptive Machine Systems, and 4 Research Institutes: Center for Atomic and Molecular Technologies, Welding and Joining Research Institute, Institute of Scientific and Industrial Research and Research Center for Ultra-High Voltage Electron Microscopy. Recently, materials research, particularly that of metallic materials, has specialized only in individual elemental characteristics and narrow specialty fields, and there is a feeling that the original role of materials research has been forgotten. The 6 educational and research organizations which make up the COE program cooperatively try to develop new advanced structural and functional materials and achieve technological breakthrough for their fabrication processes from electronic, atomic, microstructural and morphological standpoints, focusing on their design and application: development of high performance structural materials such as space plane and turbine blades operating under a severe environment, new fabrication and assembling methods for electronic devices, development of evaluation technique for materials reliability, and development of new biomaterials for regeneration of biological hard tissues. The aim of this international conference was to report the scientific progress in our Global COE program and also to discuss related research topics. The organizing committee gratefully thanks participants for presenting their recent results and for discussions with our COE members and international attendees. November 2008 Professor Tomoyuki Kakeshita Chairman of the Conference Vice Dean, Graduate School of Engineering, Osaka University, Division of Materials and Manufacturing Science, Graduate School of Engineering Leader of Global COE Program, Osaka University, ''Center of Excellence for Advanced Structural and Functional Materials Design'' Organization Chairman: T Kakeshita (Osaka University) Advisory Board:H Mehrer (University Munster, Germany), E K H Salje (University of Cambridge, United Kingdom), H-E Schaefer (University of Stuttgart, Germany), P Veyssiere (CNRS-ONERA, France) Organizing Committee: T Kakeshita, H Araki, H Fujii, S Fujimoto, Y Fujiwara, A Hirose, S Kirihara, M Mochizuki, H Mori, T Nagase, H Nakajima, T Nakano, R Nakatani, K Nogi, Y Setsuhara, Y Shiratsuchi, T Tanaka, T Terai, H Tsuchiya, N Tsuji, H Utsunomiya, H Yasuda, H Yasuda (Osaka University) Executive Committee: T Kakeshita, S Fujimoto, Y Fujiwara, A Hirose, T Tanaka, H Yasuda (Osaka University) Conference Secretariat: Y Fujiwara (Osaka University) Proceedings Editors: T Kakeshita and Y Fujiwara (Osaka University)

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International Conference on Advanced Structural and Functional Materials Design 2008

A sodium-contained amorphous titanium oxide layer having nano size mesh-like structure was fabricated on TiCuZrPd and TNTZ substrates by three different processes using alkaline solution. XPS result suggested that TiCuZrPd samples surface-modified by hydrothermal–electrochemical (HE) process exhibited the much less toxic Cu content than the original substrate composition, which is favorable for implant material. HE-processed TiCuZrPd sample had intermediated layer in which the structure was gradually changed to thickness direction with a widely diffused interface and it caused strong adhesion of hydroxyapatite layer. The nanomesh structure formed on TiCuZrPd substrate by HE process exhibited enough bioactivity in vitro test to form hydroxyapatite on their whole surface after immersing in SBF for 12 days. The surface chemical composition affects the apatite induction ability of TNTZ samples. The surface incorporation of fewer niobium species exhibited hydrophilic condition. The HE treated TNTZ sample at 90 °C for 2 h had a rough surface with fewer Nb content and it exhibited enough high bioactivity without forming any cracks or peeling.

Surface Modification with Hydrothermal–Electrochemical Technique

In the present work, we report the formation of a porous oxide/hydroxide surface layer on the Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy achieved by the combination of an alkali immersion and a potential pulse polarisation process. The alkali treatment has been employed for pure titanium to produce amorphous and porous layer prior to hydroxyapatite (HAp) growth. But, in the case of TNTZ, immersion in 5M NaOH at the open circuit potential (OCP) at 60°C for 24 hours, did not yield any uniform layer, instead a thick deposited layer with highly cracked one. The cracks were attributed to the growth of a tantalum enriched particulate. In order to avoid the crack formation, the electrochemical behaviour of the alloy and the pure alloying elements (Ti, Nb, Ta and Zr) was investigated to produce a uniform surface with the application of a square wave modulated potential pulse polarization, leading to the formation of a relatively uniform porous layer on the alloy.

http://iopscience.iop.org/article/10.1088/1742-6596/165/1/012007/pdf

Vedarajan Raman

Papers

Surface modification of β-Type titanium alloy by electrochemical potential pulse polarization