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.

Extremely high pitting resistance of NiTi shape memory alloy thin film in simulated body fluids

2008 ◽  
Vol 62 (17-18) ◽  
pp. 2791-2794 ◽  
Author(s):  
T. Shahrabi ◽  
S. Sanjabi ◽  
E. Saebnoori ◽  
Z.H. Barber
Keyword(s):  
Thin Film ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Body Fluids ◽  
Niti Shape Memory Alloy ◽  
Alloy Thin Film ◽  
Simulated Body Fluids

Excimer laser annealing of NiTi shape memory alloy thin film

2003 ◽  
Author(s):  
Qiong Xie ◽  
Weimin Huang ◽  
Ming Hui Hong ◽  
Wendong Song ◽  
Tow Chong Chong
Keyword(s):  
Thin Film ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Excimer Laser ◽  
Laser Annealing ◽  
Niti Shape Memory Alloy ◽  
Alloy Thin Film ◽  
Excimer Laser Annealing

Material and Process Development of Thin Film Shape Memory Alloy for MEMS Actuator

2015 ◽  
Author(s):  
Cory R. Knick ◽  
Christopher J. Morris
Keyword(s):  
Thin Film ◽  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Phase Change ◽  
Shape Memory ◽  
Microelectromechanical Systems ◽  
Austenite Phase ◽  
Niti Shape Memory Alloy ◽  
Scanning Calorimetry ◽  
Release Process

In this work we discuss the design and fabrication of a cantilever that may be actuated by utilizing the martensite to austenite phase transformation of a sputtered thin film of equiatomic NiTi shape memory alloy (SMA). The cantilever devices were fabricated on a silicon wafer using standard micro fabrication techniques, and may therefore be applicable to microelectromechanical systems (MEMS) switch or actuator applications. This paper details the development of a co-sputtering process to yield a SMA film with controllable composition of Ni50Ti50 and transformation temperature around 60° C. Shape memory effects were characterized using Differential Scanning Calorimetry (DSC), for which we demonstrated martensite-austenite phase change at 57° C for 1–3 um films, annealed at 600° C. We used wafer stress versus temperature measurements as additional confirmation for the repeatable measurement of reversible phase transformation peaking at 73° C upon heating. Up to 62 MPa was available for actuation during the thermally induced phase change. After exploring multiple approaches to a frontside wafer release process, we were successful in patterning and fabricating 10 um wide freestanding Ni50Ti50 cantilevers.

INFLUENCES OF HEAT TREATMENT ON TRANSFORMATION BEHAVIORS OF NEAR-EQUIATOMIC POROUS NITI SHAPE MEMORY ALLOY

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2410-2416
Author(s):  
H. C. JIANG ◽  
Y. CHEN ◽  
S. W. LIU ◽  
L. J. RONG
Keyword(s):  
Heat Treatment ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Niti Alloy ◽  
Niti Shape Memory Alloy ◽  
Scanning Calorimetry ◽  
Pore Characteristics ◽  
Transformation Temperatures ◽  
Porous Niti ◽  
High Temperature Synthesis

The pore characteristics and pore size distribution of porous near-equiatomic NiTi shape memory alloy fabricated by self-propagating high-temperature synthesis (SHS) are described in detail. The effects of different heat treatments on the transformation of porous NiTi alloy were investigated by differential scanning calorimetry (DSC), x-ray diffraction (XRD), and scanning electron microscopy (SEM). The results indicate that heat treatment had strong influences on the transformation temperatures and latent heats of transformation. When the porous alloy was annealed at 648K and 748K for 3.6ks, two steps transformation including R transformation occurred during cooling and heating and the R transformation temperatures are lower than B 2↔ B 19' transformation temperatures. However, no transformation was detected within the experimental temperature range if the porous alloy was solution treated at 1133K for 2.4ks. This novel phenomenon was the results of extensive Ti2Ni intermetallic compound precipitation. The transformation temperatures of porous NiTi alloy after annealing at 1323K for 3.6ks were much lower than those of the untreated alloy.

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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