scholarly journals NiTi shape memory alloy: physical and tribological characterization

2018 ◽  
Vol 27 (1-2) ◽  
Author(s):  
Pardeep Sharma
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Wear Behavior ◽  
Research Work ◽  
Constant Load ◽  
Binder Content ◽  
Niti Shape Memory Alloy ◽  
X Ray Diffraction ◽  
The Coefficient Of Friction ◽  
Tribological Characterization

AbstractThe current research work focuses on the mechanical and tribological behavior of an NiTi shape memory alloy (SMA) processed with the help of powder metallurgy. SMAs have found applications in the medical, space and aerospace industries with usage in the manufacturing of microelectromechanicals (MEMS) and as actuators in the electronic industry. The wear behavior of a material greatly affects its performance. The wear behavior of an SMA can be determined with the help of the dry abrasion test. The increase in binder content and rotational speed at a constant load increases the wear rate of SMA alloys. The coefficient of friction decreases with the usage of alloys. A decrease in density has been found, as well as porosity, with the increasing content of binder in the alloy. Density decreases from 6.7 to 5.1 g/cm3 while porosity decreases from 57 to 23% with increased binder content. Scanning electron microscopy (SEM) and X-ray diffraction has been used for the investigation of surface morphology and phases present in the alloy.

Response of Optical Fiber Bragg Sensors With a Thin Film Shape Memory Alloy Coating

2008 ◽  
Author(s):  
K. P. Mohanchadra ◽  
Michael C. Emmons ◽  
Sunny Karnani ◽  
Gregory P. Carman ◽  
W. Lance Richards
Keyword(s):  
Thin Film ◽  
Shape Memory Alloy ◽  
Optical Fiber ◽  
Shape Memory ◽  
Alloy Coating ◽  
Niti Shape Memory Alloy ◽  
Alloy Thin Film ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Transformation Temperatures

This paper describes the sputter deposition and characterization of nickel titanium (NiTi) shape memory alloy thin film onto the surface of an optical fiber Bragg sensor. The NiTi coating uniformity, crystallinity and transformation temperatures are measured using scanning electron microsocopy, x-ray diffraction and differential scanning calorimetry respectively. The strain in the optical fiber is measured using centroid calculation of wavelength shifts. Results show distinct and abrupt changes in the optical fiber signal with the four related transformation temperatures represented by the austenite-martensite forward and reverse phase transformations. These tests demonstrate a coupling present between optical energy and thermal energy, i.e. a modified multiferroic material.

Characterization of Nitrided/Oxidized Layers Covering Ni-Ti Shape Memory Alloy

2007 ◽  
Vol 130 ◽  
pp. 151-154 ◽  
Author(s):  
Tomasz Goryczka ◽  
Paweł Pączkowski ◽  
Józef Lelątko ◽  
Tadeusz Wierzchoń ◽  
Henryk Morawiec
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Niti Shape Memory Alloy ◽  
X Ray Diffraction ◽  
High Temperature Process ◽  
Oxygen Addition ◽  
Discharge Method ◽  
Increase Corrosion Resistance ◽  
Low Temperature Process

In order to increase corrosion resistance, the NiTi shape memory alloy was covered by protection layers using glow discharge method. Samples were nitrided with some oxygen addition at temperatures: 350, 380, 400 and 800°C. Microstructure and sequence of obtained layers were studied applying X-ray diffraction technique as well as electron microscopy. Low temperature process produces a layers which consist of Ti3O5, TiN and Ni2Ti4O. Intermediate Ni3Ti layer was between Ni2Ti4O and NiTi matrix. High temperature process forms TiO2 and TiN with interlayer Ti2Ni. Surface does not contain phase with Ni, which is considered as toxic element.

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.

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