Structure Control of Bioactive Titanate Nanomesh Layers Fabricated on Laser Irradiated Ti-based Bulk Metallic Glass usin
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Structure Control of Bioactive Titanate Nanomesh Layers Fabricated on Laser Irradiated Ti-based Bulk Metallic Glass using Hydrothermal-Electrochemical Method Sayaka Maruyama1, Naota Sugiyama1, Masahiro Yoshimura2, Togo Shinonaga3, Masahiro Tsukamoto3, Nobuyuki Abe3, Takeshi Wada4, Xinmin Wang4, Akihisa Inoue4, Kiyoshi Okada1 and Nobuhiro Matsushita1 1 Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama, Kanagawa, Japan 2 Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan 3 Joining and Welding Research Institute, Osaka University, baraki, Osaka, Japan 4 Institute of Materials Research, Tohoku University, Miyagi, Japan ABSTRACT The surface of Ti-based bulk metallic glass (BMG) was irradiated by the femto-second laser and microgrooves were formed on the surface. The titanate nanomesh layers were fabricated on the micro-grooved BMG surface by hydrothermal-electrochemical (H-E) treatment changing the conditions of the concentration of electrolyte solution (0 and 5 M) and applying current density (0-200 mA/cm2). The bone-inducing capacity of the samples with different H-E treatment was confirmed by soaking them in a simulated body fluid for 12 days. The H-E treatment in higher concentration 5 M NaOH aq. and applying higher current density above 0.5 mA/cm2 exhibited excellent bioactivity inducing large hydroxyapatite crystallites. INTRODUCTION A series of Ti-based bulk metallic glasses (BMGs) have been studied extensively because of their excellent mechanical properties, i.e. low Young’s modulus, high elastic limit, high corrosion resistance and high abrasion resistance [1-6]. They, however, contain toxic elements for the human body, such as Ni, Al and Be to enhance higher glass-forming ability. Recently, Tibased BMGs with less toxic elements were developed for biomedical applications. However, they may not be directly joined to human bones because of their high chemical stability and bioinertness. The materials having bioactivity are, therefore, necessary between BMG and human bones. In our previous studies, we succeeded in giving bioactivity to the surface of Ti-based BMG (Ti40Zr10Cu36Pd14) by fabricating titanate nanomesh layers on it using hydrothermalelectrochemical (H-E) treatment [7, 8]. It was found that the layer whose surface area exceeded a certain value showed a good bone-inducing capacity. We utilized the femtosecond laser to make surface area of the BMG larger. The irradiation of the femtosecond laser formed the submicron groves on the metal surface without heat-affect zone [9, 10]. Recently, it was reported that periodic microstructures were fabricated on titanium plate and the structures control was possible by changing the laser fluence [11]. A similar result was provided on Ti-based BMG and the periodic microstructures parallel to the laser electric polarization field vector were formed by applying the laser fluence of 0.15 J/cm2 and the microstructures having deep grooves were formed by increasing laser fluence to 1.0 J/cm2. In the present study, we
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