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R O Ritchie - One of the best experts on this subject based on the ideXlab platform.
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effect of product form and heat treatment on the crystallographic texture of austenitic nitinol
Journal of Materials Science, 2006Co-Authors: S W Robertson, Xiaoyan Gong, R O RitchieAbstract:The superelastic material Nitinol, a nearly equiatomic alloy of nickel and titanium, is rapidly becoming one of the most important Metallic Implant materials in the biomedical industry, especially for the fabrication of endovascular stents. The manufacture of these stents, and countless other Nitinol products, originates from various forms of raw material such as tube, sheet or rod. However, depending upon which product form is used, the crystallographic texture in Nitinol can be significantly different, which can lead to marked changes in its mechanical properties. In this paper, we present a study to show the characteristic texture in various Nitinol product forms (tube, sheet, and rod), before and after annealing heat treatments, with specific quantification of the major texture components. We further present predictions of the mechanical response based upon such texture, and provide experimental verification with uniaxial tensile tests. Results show that the form of the starting material has a profound influence on characteristic texture and predicted mechanical response. Furthermore, annealing heat treatments, rather than reducing the texture, are found to increase the strength of this texture.
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crystallographic texture for tube and plate of the superelastic shape memory alloy nitinol used for endovascular stents
Journal of Biomedical Materials Research Part A, 2005Co-Authors: S W Robertson, V. Imbeni, Hans-rudolf Wenk, R O RitchieAbstract:The superelastic/shape-memory material, Nitinol, an approximately equiatomic alloy of Ni and Ti, is rapidly becoming one of the most important Metallic Implant materials in the biomedical industry, in particular for the manufacture of endovascular stents. As such stents are invariably laser-machined from Nitinol tubes or sheets rolled into tubes, it is important to fully understand the physical phenomena that may affect the mechanical behavior of this material. With tubing and plate, one major issue is crystallographic texture, which can play a key role in influencing the mechanical properties of Nitinol. In this article, we present a study on how geometry and heat treatment can affect the texture of Nitinol, with specific quantification of the texture of Nitinol tube used for the production of endovascular stents. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 72A: 190–199, 2005
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crystallographic texture for tube and plate of the superelastic shape memory alloy nitinol used for endovascular stents
Journal of Biomedical Materials Research Part A, 2005Co-Authors: S W Robertson, V. Imbeni, Hans-rudolf Wenk, R O RitchieAbstract:The superelastic/shape-memory material, Nitinol, an approximately equiatomic alloy of Ni and Ti, is rapidly becoming one of the most important Metallic Implant materials in the biomedical industry, in particular for the manufacture of endovascular stents. As such stents are invariably laser-machined from Nitinol tubes or sheets rolled into tubes, it is important to fully understand the physical phenomena that may affect the mechanical behavior of this material. With tubing and plate, one major issue is crystallographic texture, which can play a key role in influencing the mechanical properties of Nitinol. In this article, we present a study on how geometry and heat treatment can affect the texture of Nitinol, with specific quantification of the texture of Nitinol tube used for the production of endovascular stents.
S W Robertson - One of the best experts on this subject based on the ideXlab platform.
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effect of product form and heat treatment on the crystallographic texture of austenitic nitinol
Journal of Materials Science, 2006Co-Authors: S W Robertson, Xiaoyan Gong, R O RitchieAbstract:The superelastic material Nitinol, a nearly equiatomic alloy of nickel and titanium, is rapidly becoming one of the most important Metallic Implant materials in the biomedical industry, especially for the fabrication of endovascular stents. The manufacture of these stents, and countless other Nitinol products, originates from various forms of raw material such as tube, sheet or rod. However, depending upon which product form is used, the crystallographic texture in Nitinol can be significantly different, which can lead to marked changes in its mechanical properties. In this paper, we present a study to show the characteristic texture in various Nitinol product forms (tube, sheet, and rod), before and after annealing heat treatments, with specific quantification of the major texture components. We further present predictions of the mechanical response based upon such texture, and provide experimental verification with uniaxial tensile tests. Results show that the form of the starting material has a profound influence on characteristic texture and predicted mechanical response. Furthermore, annealing heat treatments, rather than reducing the texture, are found to increase the strength of this texture.
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crystallographic texture for tube and plate of the superelastic shape memory alloy nitinol used for endovascular stents
Journal of Biomedical Materials Research Part A, 2005Co-Authors: S W Robertson, V. Imbeni, Hans-rudolf Wenk, R O RitchieAbstract:The superelastic/shape-memory material, Nitinol, an approximately equiatomic alloy of Ni and Ti, is rapidly becoming one of the most important Metallic Implant materials in the biomedical industry, in particular for the manufacture of endovascular stents. As such stents are invariably laser-machined from Nitinol tubes or sheets rolled into tubes, it is important to fully understand the physical phenomena that may affect the mechanical behavior of this material. With tubing and plate, one major issue is crystallographic texture, which can play a key role in influencing the mechanical properties of Nitinol. In this article, we present a study on how geometry and heat treatment can affect the texture of Nitinol, with specific quantification of the texture of Nitinol tube used for the production of endovascular stents. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 72A: 190–199, 2005
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crystallographic texture for tube and plate of the superelastic shape memory alloy nitinol used for endovascular stents
Journal of Biomedical Materials Research Part A, 2005Co-Authors: S W Robertson, V. Imbeni, Hans-rudolf Wenk, R O RitchieAbstract:The superelastic/shape-memory material, Nitinol, an approximately equiatomic alloy of Ni and Ti, is rapidly becoming one of the most important Metallic Implant materials in the biomedical industry, in particular for the manufacture of endovascular stents. As such stents are invariably laser-machined from Nitinol tubes or sheets rolled into tubes, it is important to fully understand the physical phenomena that may affect the mechanical behavior of this material. With tubing and plate, one major issue is crystallographic texture, which can play a key role in influencing the mechanical properties of Nitinol. In this article, we present a study on how geometry and heat treatment can affect the texture of Nitinol, with specific quantification of the texture of Nitinol tube used for the production of endovascular stents.
Liming Fang - One of the best experts on this subject based on the ideXlab platform.
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silver nanoparticles and growth factors incorporated hydroxyapatite coatings on Metallic Implant surfaces for enhancement of osteoinductivity and antibacterial properties
ACS Applied Materials & Interfaces, 2014Co-Authors: Chaoming Xie, Kefeng Wang, Fanzhi Meng, Ou Jiang, Hongping Zhang, Wei Zhi, Liming FangAbstract:Research on incorporation of both growth factors and silver (Ag) into hydroxyapatite (HA) coatings on Metallic Implant surfaces for enhancing osteoinductivity and antibacterial properties is a challenging work. Generally, Ag nanoparticles are easy to agglomerate and lead to a large increase in local Ag concentration, which could potentially affect cell activity. On the other hand, growth factors immobilization requires mild processing conditions so as to maintain their activities. In this study, bone morphology protein-2 (BMP-2) and Ag nanoparticle contained HA coatings were prepared on Ti surfaces by combining electrochemical deposition (ED) of Ag and electrostatic immobilization of BMP-2. During the ED process, chitosan (CS) was selected as the stabilizing agent to chelate Ag ions and generate Ag nanoparticles that are uniformly distributed in the coatings. CS also reduces Ag toxicity while retaining its antibacterial activity. Afterwards, a BMP/heparin solution was absorbed on the CS/Ag/HA coatings. Consequently, BMP-2 was immobilized on the coatings by the electrostatic attraction between CS, heparin, and BMP-2. Sustained release of BMP-2 and Ag ions from HA coatings was successfully demonstrated for a long period. Results of antibacterial tests indicate that the CS/Ag/HA coatings have high antibacterial properties against both Staphylococcus epidermidis and Escherichia coli. Osteoblasts (OB) culture reveals that the CS/Ag/HA coatings exhibit good biocompatibility. Bone marrow stromal cells (BMSCs) culture indicates that the BMP/CS/Ag/HA coatings have good osteoinductivity and promote the differentiation of BMSCs. Ti bars with BMP/CS/Ag/HA coatings were Implanted into the femur of rabbits to evaluate the osteoinductivity of the coatings. Results indicate that BMP/CS/Ag/HA coatings favor bone formation in vivo. In summary, this study presents a convenient and effective method for the incorporation of growth factors and antibacterial agents into HA coatings. This method can be utilized to modify a variety of Metallic Implant surfaces.
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silver nanoparticles and growth factors incorporated hydroxyapatite coatings on Metallic Implant surfaces for enhancement of osteoinductivity and antibacterial properties
ACS Applied Materials & Interfaces, 2014Co-Authors: Xiong Lu, Kefeng Wang, Fanzhi Meng, Ou Jiang, Hongping Zhang, Liming FangAbstract:Research on incorporation of both growth factors and silver (Ag) into hydroxyapatite (HA) coatings on Metallic Implant surfaces for enhancing osteoinductivity and antibacterial properties is a challenging work. Generally, Ag nanoparticles are easy to agglomerate and lead to a large increase in local Ag concentration, which could potentially affect cell activity. On the other hand, growth factors immobilization requires mild processing conditions so as to maintain their activities. In this study, bone morphology protein-2 (BMP-2) and Ag nanoparticle contained HA coatings were prepared on Ti surfaces by combining electrochemical deposition (ED) of Ag and electrostatic immobilization of BMP-2. During the ED process, chitosan (CS) was selected as the stabilizing agent to chelate Ag ions and generate Ag nanoparticles that are uniformly distributed in the coatings. CS also reduces Ag toxicity while retaining its antibacterial activity. Afterwards, a BMP/heparin solution was absorbed on the CS/Ag/HA coatings. Co...
Mitsuo Niinomi - One of the best experts on this subject based on the ideXlab platform.
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optimization of cr content of metastable β type ti cr alloys with changeable young s modulus for spinal fixation applications
Acta Biomaterialia, 2012Co-Authors: Xingfeng Zhao, Mitsuo Niinomi, Masaaki Nakai, Junko Hieda, Takuya Ishimoto, Takayoshi NakanoAbstract:Abstract Metallic Implant rods used in spinal fixtures should have a Young’s modulus that is sufficiently low to prevent stress shielding for the patient and sufficiently high to suppress springback for the surgeon. Therefore, we propose a new concept: novel biomedical titanium alloys with a changeable Young’s modulus via deformation-induced ω phase transformation. In this study, the Cr content in the range of 10–14 mass% was optimized to produce deformation-induced ω phase transformation, resulting in a large increase in the Young’s modulus of binary Ti–Cr alloys. The springback and cytotoxicity of the optimized alloys were also examined. Ti–(10–12)Cr alloys exhibit an increase in Young’s modulus owing to deformation-induced ω phase transformation. In this case, such deformation-induced ω phase transformation occurs along with {3 3 2} β mechanical twinning, resulting in the maintenance of acceptable ductility with relatively high strength. Among the examined alloys, the lowest Young’s modulus and largest increase in Young’s modulus are obtained from the Ti–12Cr alloy. This alloy exhibits smaller springback than and comparable cytocompatibility to the biomedical Ti alloy Ti–29Nb–13Ta–4.6Zr.
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self adjustment of young s modulus in biomedical titanium alloys during orthopaedic operation
Materials Letters, 2011Co-Authors: Masaaki Nakai, Mitsuo Niinomi, Xingfeng Zhao, Xiaoli ZhaoAbstract:Abstract In spinal fixation devices, the Young's modulus of the Metallic Implant rod should be not only sufficiently low to prevent stress shielding for the patient but also sufficiently high to suppress springback for the surgeon. This paper proposes a novel function of biomedical titanium alloys—self-adjustment of Young's modulus. Deformation-induced ω phase transformation was introduced into β-type titanium alloys so that the Young's modulus of only the deformed part would increase during operation, while that of the non-deformed part would remain low. The Young's modulus increase by deformation was investigated for a binary Ti-12Cr alloy. This alloy successfully underwent deformation-induced ω phase transformation and exhibited the increase in the Young's modulus by deformation.
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mechanical properties of biomedical titanium alloys
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 1998Co-Authors: Mitsuo NiinomiAbstract:Abstract Titanium alloys are expected to be much more widely used for Implant materials in the medical and dental fields because of their superior biocompatibility, corrosion resistance and specific strength compared with other Metallic Implant materials. Pure titanium and Ti–6Al–4V, in particular, Ti–6Al–4V ELI have been, however, mainly used for Implant materials among various titanium alloys to date. V free alloys like Ti–6Al–7Nb and Ti–5Al–2.5Fe have been recently developed for biomedical use. More recently V and Al free alloys have been developed. Titanium alloys composed of non-toxic elements like Nb, Ta, Zr and so on with lower modulus have been started to be developed mainly in the USA. The β type alloys are now the main target for medical materials. The mechanical properties of the titanium alloys developed for Implant materials to date are described in this paper.
Hans-rudolf Wenk - One of the best experts on this subject based on the ideXlab platform.
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crystallographic texture for tube and plate of the superelastic shape memory alloy nitinol used for endovascular stents
Journal of Biomedical Materials Research Part A, 2005Co-Authors: S W Robertson, V. Imbeni, Hans-rudolf Wenk, R O RitchieAbstract:The superelastic/shape-memory material, Nitinol, an approximately equiatomic alloy of Ni and Ti, is rapidly becoming one of the most important Metallic Implant materials in the biomedical industry, in particular for the manufacture of endovascular stents. As such stents are invariably laser-machined from Nitinol tubes or sheets rolled into tubes, it is important to fully understand the physical phenomena that may affect the mechanical behavior of this material. With tubing and plate, one major issue is crystallographic texture, which can play a key role in influencing the mechanical properties of Nitinol. In this article, we present a study on how geometry and heat treatment can affect the texture of Nitinol, with specific quantification of the texture of Nitinol tube used for the production of endovascular stents. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 72A: 190–199, 2005
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crystallographic texture for tube and plate of the superelastic shape memory alloy nitinol used for endovascular stents
Journal of Biomedical Materials Research Part A, 2005Co-Authors: S W Robertson, V. Imbeni, Hans-rudolf Wenk, R O RitchieAbstract:The superelastic/shape-memory material, Nitinol, an approximately equiatomic alloy of Ni and Ti, is rapidly becoming one of the most important Metallic Implant materials in the biomedical industry, in particular for the manufacture of endovascular stents. As such stents are invariably laser-machined from Nitinol tubes or sheets rolled into tubes, it is important to fully understand the physical phenomena that may affect the mechanical behavior of this material. With tubing and plate, one major issue is crystallographic texture, which can play a key role in influencing the mechanical properties of Nitinol. In this article, we present a study on how geometry and heat treatment can affect the texture of Nitinol, with specific quantification of the texture of Nitinol tube used for the production of endovascular stents.