The Experts below are selected from a list of 6603 Experts worldwide ranked by ideXlab platform

Yufeng Zheng - One of the best experts on this subject based on the ideXlab platform.

  • tantalum coated Niti Alloy by piiid for biomedical application
    Surface & Coatings Technology, 2013
    Co-Authors: Y. Zhou, Y. Cheng, Yufeng Zheng, Ming Li, Tingfei Xi
    Abstract:

    Abstract Plasma immersion ion implantation deposition (PIIID) technique was employed to fabricate tantalum coatings on Niti Alloys with the aim to obtain a more adherent, corrosion resistant and radiopaque coatings in our present study. The surface characteristics and corrosion behavior were investigated by SEM, AFM, XRD, AES, XPS and electrochemical measurement. The results show that a relatively rough, dense and adhesive tantalum coating has been successfully fabricated on Niti Alloy by the PIIID method with the thickness of about 3.3 μm. The surface topography of the tantalum coatings is characterized by regularly spaced grain facets. The coating is combined with a mixture of predominantly α-phase tantalum with a small concentration of β-phase tantalum. The outmost surface of the coating is oxidized, consisting of majority of stoichiometric Ta 2 O 5 and a small quantity of Ta 2 O 5 − X . It can be concluded that the dense and adhesive tantalum coatings on Niti Alloy improve its corrosion resistance, implying the decrease of Ni ions released into human body fluids.

  • the influence of laser welding parameters on the microstructure and mechanical property of the as jointed Niti Alloy wires
    Materials Letters, 2008
    Co-Authors: Yi Guo Song, Yufeng Zheng, W S Li, Li Li
    Abstract:

    Abstract The Nd:YAG laser welding was used to join the binary Niti Alloy wires with different compositions(Ti–50.0 at.%Ni and Ti–50.9 at.%Ni) which had the same diameter of 1 mm. The wires were welded with different parameters, including impulse width and welding current. The aim was to assess the influence of the laser-welding process on the microstructure and mechanical properties of the welded joint of binary Niti wires. The optical microscopy (OM) and the metallographic microscopy (MM) were used to analyze the microstructure of the welded joints. The tensile test and the differential scanning calorimetry (DSC) were carried out to examine the ultimate tensile strength and the reverse martensitic transformation temperatures of the welded joints. It was found that the welding current and the impulse width had great influence on the quality of the welded joints, an optimal parameter combination would remove the pores and micro-cracks appeared in the fusion zone, and result in good mechanical properties such as higher fracture strength and elongation. The laser welding had a few effect on the reverse martensitic transformation temperatures of the welded joints.

  • surface characterization and mechanical property of tin ti coated Niti Alloy by piiid
    Surface & Coatings Technology, 2007
    Co-Authors: Y Y Cheng, Yufeng Zheng
    Abstract:

    Abstract A hard and adherent TiN/Ti thin film of approximately 3 μm in thickness was deposited on the surface of Ti–50.6 at.% Ni Alloy by the PIIID technique. The surface composition and chemical state of the coated samples were evaluated by XPS. The XPS results indicate that titanium oxide and titanium oxynitride were present on the TiN surface. The spectra of Ti 2p, N 1s, O 1s and C 1s electrons before and after the film being sputter etched were also discussed. Scanning electron microscopy (SEM) and energy disperse spectroscopy (EDS) analyses demonstrate that an interfacial layer, containing Ti, N and Ni, was formed at the interface between the TiN and Ti coatings. Sliding wear tests show that the TiN coating significantly reduces the friction coefficient and improves wear resistance of the Niti Alloy.

  • surface modification of Niti Alloy with tantalum to improve its biocompatibility and radiopacity
    Journal of Materials Science, 2006
    Co-Authors: Y. Cheng, Huan Li, Yufeng Zheng
    Abstract:

    Nickel–titanium Alloy, with the features of shape memory effect, superelasticity and biocompatibility offers many unique advantages for the biomedical application. These applications have included everything from surgical tools to permanent implants [1–3]. However, many researchers highlighted the selective dissolution of Ni ion from the Niti Alloy during the corrosion process, which could lead to potential danger [4–6]. Different surface treatments have been investigated to improve the corrosion resistance of Niti implants [7–10]. In modern medicines, to analyze the motion of implants, it is necessary to estimate the 3D position and orientation of each component using radiography [11]. When small stents, guidewires and catheter are quite thin and space farther apart, the detection of the implantable devices or tools become very difficult [12, 13]. The methods to enhance the visibility under X-ray include adding a mark of noble metals and coating with gold, etc. Although gold plating of Nitinol components to improve the radiopacity has been achieved by means of electroplating technique, problems such as risks of galvanic corrosion, biocompatibility and hydrogen embrittlement still exist [14]. Tantalum metal has successfully been used for implants for half a century [15]. Since the galvanic potentials of tantalum and Nitinol are very similar, the galvanic corrosion effect is almost immeasurable and complete failure of the implants is impossible [16]. Tantalum and tantalum oxide particles are often used to improve radiopacity of other materials [17, 18]. No problems have been reported concerning its biocompatibility [19–22]. It has been found that tantalum coatings are 100% pinhole-free and show great potential within both industrial and medical applications [23]. Tantalum coating with a very ductile nature is suitable where a product can be improved by combining material characteristics of the substrate with an exceptional corrosion-resistant surface [24, 25]. As a result, tantalum is an excellent candidate for usage as coatings for Niti Alloys to improve its anti-corrosion property and radiopacity. For coating applications, a good bonding strength between the coating and the substrate is required in order to ensure the lifetime service in the implanting environment [26]. The multi arc ion-plating technique, with the feature of high packing density and good adhesion, can satisfy this requirement [27]. Accordingly, the purpose of the present study is to develop a novel biocompatible and radiopaque Ta coating on Niti Alloy by multi-arc ion plating technique, the surface characterization, corrosion behavior and hemocompatibility are investigated. The chemical composition of the experimental Alloy was Ti-50.6 at%. All samples were mechanically polished to 1 lm and then ultrasonically cleaned in acetone, alcohol and distilled water successively, then dried and loaded into the deposition chamber. The tantalum coatings were deposited by multi arc ion-plating technique [27]. Prior to deposition, the surfaces of the Niti Alloy substrates were further cleaned by Ar ion bombardment with energy of 1100 eV for 10 min. And the temperature of the Niti Alloy substrates was held to be 300 C. The substrate bias voltages were controlled to be )300 V with an arc current be 75 A, deposition pressure Y. Cheng AE Y. F. Zheng (&) Department of Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871, China e-mail: yfzheng@pku.edu.cn

Ruiqiang Hang - One of the best experts on this subject based on the ideXlab platform.

  • Preparation and cytocompatibility of Ni-Ti-O nanospindles on Niti Alloy
    Materials Letters, 2019
    Co-Authors: Ya Zhao, Ruiqiang Hang, Jin Zhang
    Abstract:

    Abstract The present work reports on the hydrothermal conversion of Ni-Ti-O nanopores anodically grown on Niti Alloy into nanospindles and their cytocompatibility. The results show the amorphous nanopores can transform to anatase nanospindles with length concentrated at 70–110 nm and diameter at 16–24 nm upon hydrothermal treatment at 200 °C in pure water for 2 h. The nanospindles also can promote proliferation of bone marrow mesenchymal stem cells when compared with that of nanopores and bare Niti Alloy thus are promising as biomedical coatings of Niti Alloy.

  • Electrochemical synthesis, corrosion behavior and cytocompatibility of Ni-Ti-O nanopores on Niti Alloy
    Materials Letters, 2017
    Co-Authors: Ruiqiang Hang, Mingxiang Zong, Xin Wang, Xiangyu Zhang, Xiaobo Huang, Bin Tang
    Abstract:

    Abstract In the present work, we report the anodic growth of Ni-Ti-O nanopores (NPs) on Niti Alloy in ethylene glycol (EG) electrolyte containing H 2 O and NaBr. It is shown that the NPs with diameter concentrated at 50–60 nm can be grown at 10 V in EG electrolyte containing 5 vol% H 2 O and 0.48 M NaBr. The NP-coated Niti Alloy show lower corrosion current density compared with that of the bare Niti Alloy. In addition, the NPs possess good cytocompatibility and can even promote osteoblast spreading. Good corrosion resistance and cytocompatibility render the Ni-Ti-O NPs promising as coating of the Niti Alloy for biomedical applications.

  • relationship between ni release and cytocompatibility of ni ti o nanotubes prepared on biomedical Niti Alloy
    Corrosion Science, 2017
    Co-Authors: Mingxiang Zong, Ruiqiang Hang, Bin Tang
    Abstract:

    Abstract To elucidate the relationship between Ni release and cytocompatibility of Niti Alloy, Ni-Ti-O nanotubes (NTs) are produced on its surface by anodization followed by annealing. The Niti control has higher corrosion current density but releases less Ni than anodized samples, suggesting chemical dissolution of the NTs also contributes to Ni release. Although the annealed NTs release more Ni than that of Niti control, they possess similar cytocompatibility. In addition, cytocompatibilitiy of the NTs with similar surface properties but have different Ni release levels is also comparable. These results suggest the amount of released Ni has little influence on the cytocompatibility.

  • fabrication of irregular layer free and diameter tunable ni ti o nanopores by anodization of Niti Alloy
    Electrochemistry Communications, 2017
    Co-Authors: Ruiqiang Hang, Ya Zhao, Xiangyu Zhang, Xiaobo Huang, Bin Tang
    Abstract:

    Abstract Ni–Ti–O nanopores (NPs) free of irregular surface layers and with tunable diameters are prepared by anodizing Niti Alloy in glycerol containing H 2 O and NaCl. In an electrolyte composed of glycerol, 10 vol% H 2 O and 0.6 M NaCl, NPs with diameters between 23 and 39 nm can be produced at anodization voltages between 20 and 80 V. In this electrolyte system, the irregular oxide layer on the surface can be completely removed chemically and/or mechanically during anodization. The resulting Ni–Ti–O NPs with tunable diameters should prove useful, for example, in energy, environmental and biomedical applications.

  • in situ synthesis of ni oh 2 tio2 composite film on Niti Alloy for non enzymatic glucose sensing
    Sensors and Actuators B-chemical, 2016
    Co-Authors: Xuming Zhang, Xiang Peng, Hao Wu, Guosong Wu, Ruiqiang Hang
    Abstract:

    Abstract A one-step potential cycling technique for in situ synthesis of electroactive Ni(OH)2 and protective TiO2 composite film on Niti Alloy is described. The Ni(OH)2/TiO2 composite film can be used directly as the electrode in a non-enzymatic glucose sensor. This binder-free sensor boasts a high glucose sensitivity of 192 μA mM−1 cm−2, short response time of less than 1 s, and detection limit of 8 μM. In addition, the stable and protective TiO2 extends the linear range to 14 mM and provides excellent long-term stability. This novel fabrication method not only simplifies the preparation of high-performance non-enzymatic glucose sensing materials, but also can be readily extended to the fabrication of other transition metal-based biosensors.

Bin Tang - One of the best experts on this subject based on the ideXlab platform.

  • Electrochemical synthesis, corrosion behavior and cytocompatibility of Ni-Ti-O nanopores on Niti Alloy
    Materials Letters, 2017
    Co-Authors: Ruiqiang Hang, Mingxiang Zong, Xin Wang, Xiangyu Zhang, Xiaobo Huang, Bin Tang
    Abstract:

    Abstract In the present work, we report the anodic growth of Ni-Ti-O nanopores (NPs) on Niti Alloy in ethylene glycol (EG) electrolyte containing H 2 O and NaBr. It is shown that the NPs with diameter concentrated at 50–60 nm can be grown at 10 V in EG electrolyte containing 5 vol% H 2 O and 0.48 M NaBr. The NP-coated Niti Alloy show lower corrosion current density compared with that of the bare Niti Alloy. In addition, the NPs possess good cytocompatibility and can even promote osteoblast spreading. Good corrosion resistance and cytocompatibility render the Ni-Ti-O NPs promising as coating of the Niti Alloy for biomedical applications.

  • relationship between ni release and cytocompatibility of ni ti o nanotubes prepared on biomedical Niti Alloy
    Corrosion Science, 2017
    Co-Authors: Mingxiang Zong, Ruiqiang Hang, Bin Tang
    Abstract:

    Abstract To elucidate the relationship between Ni release and cytocompatibility of Niti Alloy, Ni-Ti-O nanotubes (NTs) are produced on its surface by anodization followed by annealing. The Niti control has higher corrosion current density but releases less Ni than anodized samples, suggesting chemical dissolution of the NTs also contributes to Ni release. Although the annealed NTs release more Ni than that of Niti control, they possess similar cytocompatibility. In addition, cytocompatibilitiy of the NTs with similar surface properties but have different Ni release levels is also comparable. These results suggest the amount of released Ni has little influence on the cytocompatibility.

  • fabrication of irregular layer free and diameter tunable ni ti o nanopores by anodization of Niti Alloy
    Electrochemistry Communications, 2017
    Co-Authors: Ruiqiang Hang, Ya Zhao, Xiangyu Zhang, Xiaobo Huang, Bin Tang
    Abstract:

    Abstract Ni–Ti–O nanopores (NPs) free of irregular surface layers and with tunable diameters are prepared by anodizing Niti Alloy in glycerol containing H 2 O and NaCl. In an electrolyte composed of glycerol, 10 vol% H 2 O and 0.6 M NaCl, NPs with diameters between 23 and 39 nm can be produced at anodization voltages between 20 and 80 V. In this electrolyte system, the irregular oxide layer on the surface can be completely removed chemically and/or mechanically during anodization. The resulting Ni–Ti–O NPs with tunable diameters should prove useful, for example, in energy, environmental and biomedical applications.

  • size dependent corrosion behavior and cytocompatibility of ni ti o nanotubes prepared by anodization of biomedical Niti Alloy
    Corrosion Science, 2016
    Co-Authors: Ruiqiang Hang, Xiangyu Zhang, Xiaobo Huang, Bin Tang
    Abstract:

    Abstract We fabricate Ni–Ti–O NTs with different size on Niti Alloy through varying anodization voltages and evaluate their corrosion behavior, Ni release, and cytocompatibility. Our results show the NTs influence the corrosion behavior and cytocompatibility of Niti Alloy in a size-dependent manner. Worse corrosion resistance and more Ni release are observed from large NTs because of their high specific surface area. However, cytocompatibility is improved after anodization especially for the sample anodized at 25 V. These results thus indicate the release level of Ni ions from Niti Alloy is well tolerated by osteoblasts and surface nanotubular structure contribute to its cytocompatibility.

  • fabrication of ni ti o nanotube arrays by anodization of Niti Alloy and their potential applications
    Scientific Reports, 2015
    Co-Authors: Ruiqiang Hang, Xiangyu Zhang, Xiaobo Huang, Lingzhou Zhao, Bin Tang
    Abstract:

    Fabrication of Ni-Ti-O nanotube arrays by anodization of Niti Alloy and their potential applications

M S Yong - One of the best experts on this subject based on the ideXlab platform.

  • characterization of bioactive surface oxidation layer on Niti Alloy
    Applied Surface Science, 2005
    Co-Authors: Y W Gu, M S Yong
    Abstract:

    Abstract To enhance the bioactivity of Niti Alloy, the surface oxidation layers were synthesized by heat treatment in air in the temperature range of 300–800 °C. The surface oxidation layer on Niti Alloy was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The heat treated sample was soaked in simulated body fluid (SBF) to study the bioactivity of the thermally grown oxide layer. Results showed that a protective layer of TiO 2 was formed on the surface of Niti Alloy at heat treatment temperatures of 600 °C or higher with varying degree of anatase and rutile. Small amount of nickel oxide was found on the surface of 300 and 400 °C treated samples by X-ray photoelectron spectroscopy. With further increase in the heat treatment temperature, the nickel concentration on the surface decreased and there was almost no nickel species on the surface after heat treatment at 600 °C or 800 °C. Depth profiling revealed that the amount of TiO 2 (Ti 4+ ) decreased with depth with a concomitant increase of metallic Ti. In addition, both TiO (Ti 2+ ) and Ti 2 O 3 (Ti 3+ ) increased iNitially and then decreased gradually with depth. Ni existed mainly in the oxidized state on the surface of heat treated samples and it changed to metallic state with increasing depth. In vitro test revealed that the titanium oxide layer formed on the 600 and 800 °C heat treated samples was bioactive, and a layer of apatite was formed on the surface of the titanium oxide layer after soaking in simulated body fluid.

  • biomimetic deposition of apatite coating on surface modified Niti Alloy
    Biomaterials, 2005
    Co-Authors: Y W Gu, M S Yong
    Abstract:

    Abstract TiO 2 coatings were prepared on Niti Alloy by heat treatment in air at 300, 400, 600 and 800 °C. The heat-treated Niti Alloy was subsequently immersed in a simulated body fluid for the biomimetic deposition of the apatite layer onto the surface of TiO 2 coating. The apatite coatings as well as the surface oxide layer on Niti Alloy were characterized using scanning electron microscopy equipped with energy dispersive spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy. Results showed the samples heat-treated at 600 °C produced a layer of anatase and rutile TiO 2 on the surface of Niti. No TiO 2 was detected on the surface of Niti after heat treatment at 300 and 400 °C by X-ray diffraction, while rutile was formed on the surface of the 800 °C heat-treated sample. It was found that the 600 °C heat-treated Niti induced a layer consisted of microcrystalline carbonate containing hydroxyapatite on its surface most effectively, while 300 and 400 °C heat-treated Niti did not form apatite. This was due to the presence of anatase and/or rutile in the 600 and 800 °C heat-treated Niti which could provide atomic arrangements in their crystal structures suitable for the epitaxy of apatite crystals, and anatase had better apatite-forming ability than rutile. XPS and Raman results revealed that this apatite layer was a carbonated and non-stoichiometric apatite with Ca/P ratio of 1.53, which was similar to the human bone. The formation of apatite on 600 °C heat-treated Niti following immersion in SBF for 3 days indicated that the surface modified Niti possessed excellent bioactivity.

Fuxin Wang - One of the best experts on this subject based on the ideXlab platform.

  • Preparation and properties of titanium oxide film on Niti Alloy by micro-arc oxidation
    Applied Surface Science, 2011
    Co-Authors: Hairui Wang, Yufen Zhang, Dunbo Yu, Fuxin Wang
    Abstract:

    Abstract Titanium oxide ceramic coatings were prepared by micro-arc oxidation (MAO) in galvanostatic regime on biomedical Niti Alloy in H 3 PO 4 electrolyte using DC power supply. The surface of the coating exhibited a typical MAO porous and rough structure. The XPS analysis indicated that the coatings were mainly consisted of O, Ti, P, and a little amount of Ni, and the concentration of Ni was greatly reduced compared to that of the Niti substrate. The TF-XRD analysis revealed that MAO coating was composed of amorphous titanium oxide. The coatings were tightly adhesive to the substrates with the bonding strength more than 45 MPa, which was suitable for medical applications. The curves of potentiodynamic porlarization indicated that the corrosion resistance of Niti Alloy was significantly improved due to titanium oxide formation on Niti Alloy by MAO.

  • wear resistance of micro arc oxidation coatings on biomedical Niti Alloy
    Journal of Alloys and Compounds, 2009
    Co-Authors: J L Xu, Dunbo Yu, Fuxin Wang, L C Zhao
    Abstract:

    Abstract Protective coatings were successfully formed on biomedical Niti Alloy by micro-arc oxidation (MAO) using pulsed bipolar power supply. The coating surface exhibits a typical MAO porous structure, and the coating mainly consists of O, Al, Ti and Ni, with the atomic concentration of 65.11%, 27.77%, 2.20% and 2.8%, respectively. The thickness of MAO coating is about 24.0 μm when the duration time of the MAO treatment was 90 min at 400 V constant voltage treatment. XRD analysis showed that micro-arc oxidation coating is composed of γ-Al 2 O 3 and α-Al 2 O 3 . The wear resistance of the coatings was investigated by ball-on-disk friction test. The microhardness of the Niti Alloy is greatly enhanced due to the formation of Al 2 O 3 coating after micro-arc oxidation treatment. The friction coefficient of the coated Niti is stable at 0.85 and the wear resistance is increased by 9 times compared with uncoated Niti. The wear mechanism transforms from abrasive-dominant for the uncoated sample to adhesive-dominant for the coated sample.

  • the corrosion resistance behavior of al2o3 coating prepared on Niti Alloy by micro arc oxidation
    Journal of Alloys and Compounds, 2009
    Co-Authors: J L Xu, Dunbo Yu, Fuxin Wang, L C Zhao
    Abstract:

    Abstract Al 2 O 3 coating was prepared on biomedical Niti Alloy by micro-arc oxidation in an aluminate solution using pulsed bipolar power supply to improve the corrosion resistance. The microstructure and composition were studied by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), and thin-film X-ray diffraction (TF-XRD), respectively. The corrosion resistance in 0.9% NaCl solution was evaluated by open-circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The results show that the well-adhered coating with thickness of 4 μm consists of only Al 2 O 3 crystalline phase. The concentration of Ni on the surface is 3.33 at.%, which is greatly lower than that of Niti substrate. The results of EIS study and potentiodynamic polarization test indicate that the corrosion resistance of the coated sample is increased by about 40 times higher than that of uncoated sample.