Mechanical performance of apatite/TiO2 composite coatings formed on Ti and NiTi shape memory alloy

2008 ◽  
Vol 255 (2) ◽  
pp. 404-408 ◽  
Author(s):  
T. Sun ◽  
M. Wang
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Mechanical Performance ◽  
Composite Coatings ◽  
Niti Shape Memory Alloy

Fabrication of an Apatite/Collagen Composite Coating on the NiTi Shape Memory Alloy through Electrochemical Deposition and Coating Characterisation

2009 ◽  
Vol 618-619 ◽  
pp. 319-323 ◽  
Author(s):  
Parama Chakraborty Banerjee ◽  
Tao Sun ◽  
Jonathan H.W. Wong ◽  
Min Wang
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Composite Coating ◽  
Electrochemical Deposition ◽  
Room Temperature ◽  
Composite Coatings ◽  
Deposition Process ◽  
Niti Shape Memory Alloy ◽  
X Ray ◽  
Niti Sma

To improve the biocompatibility and bioactivity of NiTi shape memory alloy (SMA), apatite/collagen composite coatings were fabricated on the surface of NiTi SMA at room temperature using the electrochemical deposition technique. Spherical apatite particles and fibrous collagen that formed the composite coating were visible under scanning electron microscope (SEM). The Ca/P ratio of the apatite component in the coating, as determined by energy dispersive X-ray spectroscopy (EDX), was about 1.38 which is slightly higher than that of octocalcium phosphate (OCP). X-ray diffraction result showed that the apatite was amorphous, which was due to the low temperature (i.e., room temperature) deposition process. The structure of the composite coatings was further characterized using Fourier transform infrared reflection spectroscopy (FTIR). It was also found that, compared to bare NiTi SMA samples, the wettability of as-deposited samples was increased because of the formation of the composite coating.

scholarly journals Tests on Pretrained Superelastic NiTi Shape Memory Alloy Rods: Towards Application in Self-Centering Link Beams

2018 ◽  
Vol 2018 ◽  
pp. 1-13
Author(s):  
Xian Xu ◽  
Guangming Cheng ◽  
Junhua Zheng
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Strain Amplitude ◽  
Loading Rate ◽  
Mechanical Performance ◽  
Material Model ◽  
Niti Shape Memory Alloy ◽  
Test Results ◽  
Potential Applications ◽  
Strain Model

Austenitic shape memory alloy has potential applications in self-centering seismic resistant structural systems due to its superelastic response under cyclic tension. Raw austenitic SMA needs proper pretreatments and pretraining to gain a stable superelastic property. In this paper, tests are carried out to investigate the effects of pretraining, pretreatments, loading rate, and strain amplitude on the mechanical performance on austenitic SMA rods with a given size. The tested rods are to be used in a new concept self-centering steel link beam. Customized pretraining scheme and heat treatment are determined through the tests. The effects of loading rate and strain amplitude are investigated. A simplified stress-strain model for the SMA rods oriented to numerical simulations is obtained based on the test results. An example of using the simplified material model in numerical analysis of a self-centering steel link beam is conducted to validate the applicability of the model.

Mechanical Performance of the Annealed NiTi Shape Memory Alloy Coating onto 316L Stainless Bio-Steel

2010 ◽  
Vol 297-301 ◽  
pp. 365-369 ◽  
Author(s):  
Tuty Asma Abubakar ◽  
M. Rahman ◽  
Denis P. Dowling ◽  
Joseph Stokes ◽  
M.S.J. Hashmi
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Mechanical Behaviour ◽  
Mechanical Performance ◽  
Steel Substrate ◽  
Parent Phase ◽  
Alloy Coating ◽  
Niti Shape Memory Alloy ◽  
X Ray Diffraction ◽  
Ball Joints

This paper presents the mechanical performance of the annealed NiTi Shape Memory Alloy (SMA) coating deposited onto 316L stainless steel substrate. The as-deposited SMA coating, Ni55.9 Ti44.1, showed an amorphous behaviour. The crystalline NiTi (SMA) coating was produced by annealing the as-deposited NiTi with a thickness about 2.0 µm, at above its crystallisation temperature in a vacuum ambient. The annealed NiTi coatings were characterised to determine the effect of the annealing parameters on their mechanical behaviour. The NiTi phases and structures were determined by x-ray diffraction (XRD) and scanning electron microscopy (SEM) whereas the mechanical properties were measured using the Rockwell C adhesion test. Three main phases; NiTi B2 parent phase, Ni3Ti and TiO2 were found in the annealed samples and the intensities of each phase were dependent on the annealing temperature and annealing time. Each phase significantly affected the mechanical behaviour of the coatings. Higher intensities of Ni3Ti and TiO2 phases were believed to contribute to the low adhesion of the annealed NiTi coatings due to their brittle properties. The annealing parameters; 600 °C for durations of 30 min was considered as the optimum parameter, yielding no fine cracks at the Rockwell C indentation interface compared to other samples at high magnification under the SEM. Adding a hard top layer of TiN would potentially provide a hard coating with an interlayer capable of absorbing impact which would be very suitable for ball joints used in hip replacement therapy.

Electrochemical Deposition of Apatite/Collagen Composite Coating on NiTi Shape Memory Alloy and Coating Properties

2009 ◽  
Vol 1239 ◽  
Author(s):  
Min Wang ◽  
Tao Sun
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Composite Coating ◽  
Electrochemical Deposition ◽  
Composite Coatings ◽  
Surface Characteristics ◽  
Corrosion Current ◽  
Niti Shape Memory Alloy ◽  
Niti Sma ◽  
Transmission Electron

AbstractIn this investigation, an apatite/collagen composite coating was formed at 37C on a NiTi shape memory alloy (SMA) through electrochemical deposition using double-strength simulated body fluid (2SBF) which contained dissolved collagen. Surface characteristics, wettability and stability of the composite coating were subsequently studied. Scanning electron microscope (SEM) examination of the surface of composite coatings revealed that many collagen fibers were embedded in apatite with flake-like structure and apatite nanocrystals nucleated and grew on collagen fibrils. Energy dispersive X-ray (EDX) spectroscopy analysis showed that the Ca : P ratio of the composite coating was about 1.35, which is close to that of octocalcium phosphate. Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) analysis were also conducted for the composite coating. Compared to bare NiTi SMA samples, the potentiodynamic polarization curves of NiTi SMA samples with the composite coating displayed lower corrosion current density, more positive corrosion and breakdown potential, suggesting that the composite coating was chemically stable and provided corrosion resistance for NiTi SMA.

Impact protection behavior of NiTi shape memory alloy wires

2017 ◽  
Vol 700 ◽  
pp. 132-139 ◽  
Author(s):  
Chuanliang Shen ◽  
Zhipeng Wu ◽  
Zhenhai Gao ◽  
Xiaoyu Ma ◽  
Shengtong Qiu ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Niti Shape Memory Alloy ◽  
Impact Protection
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