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Dissertations / Theses on the topic 'Nickel-titanium'

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Published: 4 June 2021

Last updated: 29 May 2022

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1

Barbero, Bernal Laura Isabel. "Cyclic Behavior of Superelastic Nickel-Titanium and Nickel-Titanium-Chromium Shape Memory Alloys." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4937.

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Shape memory alloys (SMAs) are a class of alloys that display the unique ability to undergo nonlinear deformations and return to their original shape when heat is applied or the stress causing the deformation is removed. This unique shape memory characteristic is a result of a martensitic phase-change, which can be temperature induced (shape memory effect) or stress induced (superelastic effect). In this study, the cyclical behavior of NiTi, a binary shape memory alloy, is compared to the cyclical behavior of NiTiCr, a ternary SMA. The purpose of this study is to compare the behavior of a 0.085-in. diameter NiTiCr wire with the behavior of the same size NiTi wire to determine whether ternary SMAs are more viable ways to take advantage of the unique properties of SMAs for seismic applications. The experimental results showing the superelastic behavior of these alloys under cyclical tensile loading are summarized with attention to the effects of annealing temperature, strain rate, and cyclical training on the stress-strain hysteresis, maximum recoverable strain and equivalent viscous damping.

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2

Norfleet, David Matthew. "Sample size effects related to nickel, titanium and nickel-titanium at the micron size scale." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1187038020.

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3

Norfleet, David M. "Sample size effects related to nickel, titanium and nickel-titanium at the micron size scale." The Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1187038020.

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4

Ho, Wing-lam. "Flexural rigidity of nickel-titanium instruments." Click to view the E-thesis via HKUTO, 2003. http://sunzi.lib.hku.hk/hkuto/record/B31954297.

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5

Sattapan, Boonrat. "Dynamic properties of nickel-titanium instruments." Connect to thesis, 1997. http://repository.unimelb.edu.au/10187/2437.

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Root canal preparation in narrow, curved canals is a challenge even for experienced endodontists. Recently nickel-titanium (NiTi) hand files have played an important role in root canal preparation, particularly in curved root canals. Nickel-titanium endodontic instruments were first investigated in 1988 by Walia et al. who found that NiTi files have two to three times more elastic flexibility in bending and torsion, as well as superior resistance to torsional fracture compared with similar stainless steel files.

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6

Ho, Wing-lam, and 何潁琳. "Flexural rigidity of nickel-titanium instruments." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B31954297.

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7

Fretwell, Grant Michael. "On the biocompatibility of nickel titanium alloys." Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366485.

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8

Chatterjee, Sudipta. "Tribological properties of pseudo-elastic nickel-titanium." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1610048621&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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9

Strutt, Elizabeth R. "Combustion synthesis, structure and transformation characteristics of titanium carbide-nickel titanium composites /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2004. http://wwwlib.umi.com/cr/ucsd/fullcit?p3129952.

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10

Kaya, Irfan. "SHAPE MEMORY BEHAVIOR OF SINGLE AND POLYCRYSTALLINE NICKEL RICH NICKEL TITANIUM ALLOYS." UKnowledge, 2014. http://uknowledge.uky.edu/me_etds/37.

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NiTi is the most commonly used shape memory alloy (SMA) and has been widely used for bio-medical, electrical and mechanical applications. Nickel rich NiTi shape memory alloys are coming into prominence due to their distinct superelasticity and shape memory properties as compared to near equi-atomic NiTi shape memory alloys. Besides, their lower density and higher work output than steels makes these alloys an excellent candidate for aerospace and automotive industry. Shape memory properties and phase transformation behavior of high Ni-rich Ni54Ti46 (at.%) polycrystals and Ni-rich Ni51Ti49 (at.%) single-crystals are determined. Their properties are sensitive to heat treatments that affect the phase transformation behavior of these alloys. Phase transformation properties and microstructure were investigated in aged Ni54Ti46 alloys with differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) to reveal the precipitation characteristics and R-phase formation. It was found that Ni54Ti46 has the ability to exhibit perfect superelasticity under high stress levels (~2 GPa) with 4% total strain after 550°C-3h aging. Stress independent R-phase transformation was found to be responsible for the change in shape memory behavior with stress. The shape memory responses of [001], [011] and [111] oriented Ni51Ti49 single-crystals alloy were reported under compression to reveal the orientation dependence of their shape memory behavior. It has been found that transformation strain, temperatures and hysteresis, Classius-Clapeyron slopes, critical stress for plastic deformation are highly orientation dependent. The effects of precipitation formation and compressive loading at selected temperatures on the two-way shape memory effect (TWSME) properties of a [111]-oriented Ni51Ti49 shape memory alloy were revealed. Additionally, aligned Ni4Ti3 precipitates were formed in a single crystal of Ni51Ti49 alloy by aging under applied compression stress along the [111] direction. Formation of a single family of Ni4Ti3 precipitates were exhibited significant TWSME without any training or deformation. When the homogenized and aged specimens were loaded in martensite, positive TWSME was observed. After loading at high temperature in austenite, the homogenized specimen did not show TWSME while the aged specimen revealed negative TWSME.

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11

Armitage, David A. "Haemocompatibility and characterisation of modified nickel titanium surfaces." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263394.

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12

Tan, Geraldine. "Thermomechanical behaviour of NiTi /." Connect to this title, 2004. http://theses.library.uwa.edu.au/adt-WU2005.0111.

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13

Riggs, Mark R. "TIG Welding of Nickel Titanium to 304 Stainless Steel." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397607979.

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14

Ryhänen, J. (Jorma). "Biocompatibility evaluation of nickel-titanium shape memory metal alloy." Doctoral thesis, Oulun yliopisto, 1999. http://urn.fi/urn:isbn:9514252217.

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Abstract The shape memory effect, superelasticity, and good damping properties, uncommon in other implant alloys, make the nickel-titanium shape memory metal alloy (Nitinol or NiTi) a fascinating material for surgical applications. It provides a possibility to make self-locking, self-expanding and self-compressing implants. The purpose of this work was to determine if NiTi is a safe material for surgical implant applications. The primary cytotoxicity and the corrosion rate of NiTi were assessed in human osteoblast and fibroblast cell cultures. Comparisons were made with 316 LVM stainless steel (StSt) and pure titanium. The metal ions present in the media were analyzed using atomic absorption spectrometry (GFAAS). Despite the higher initial nickel dissolution, NiTi induced no toxic effects, decrease in cell proliferation or inhibition in the growth of cells in contact with the metal surface. The general soft tissue responses to NiTi were compared to corresponding responses to StSt and Ti-6Al-4V alloy in rats during a follow-up of 26 weeks. The muscular tissue response to NiTi was clearly non-toxic and non-irritating, as were also the neural and perineural responses. The overall inflammatory response and the presence of immune cells, macrophages and foreign body giant cells were similar compared to the other test materials. At 8 weeks, histomorphometry showed that the encapsule membrane of NiTi was thicker than that of stainless steel, but at 26 weeks the membrane thicknesses were equal. A regional acceleratory phenomenon (RAP) model was used to evaluate new bone formation, bone resorption and bone (re)modeling after periosteal implantation of NiTi, StSt or Ti-6Al-4V in rats using histomorphometry. Maximum new woven bone formation started earlier in the Ti-6Al-4V group than in the NiTi group, but also decreased earlier, and at 8 weeks the NiTi and StSt groups had greater cortical bone width. Later, no statistical differences were seen. NiTi had no negative effect on total new bone formation or normal RAP during a 26-week follow-up. The ultrastructural features of cell-NiTi adhesion were analyzed with scanning electron microscopy (FESEM). Cell adhesion and focal contacts showed a good acceptance of NiTi. Femoral osteotomies of rats were fixed with either NiTi or StSt intramedullary nails. Bone healing was examined with radiographs, peripheral quantitative computed tomography (pQCT) and histologically. The maximum follow-up was 60 weeks. There were more healed bone unions in the NiTi than the StSt group at early time points. Callus size and bone mineral density did not differ between the NiTi and StSt groups. Mineral density in both groups was lower in the osteotomy area than in the other areas along the nail. Density in the nail area was lower than in the proximal part of the operated femur or the contralateral femur. Bone contact to NiTi was close, indicating good tissue tolerance. Determination of trace metals from several organs was done by GFAAS or inductively coupled plasma-atomic emission spectrometry (ICP-AES). There were no statistically significant differences in nickel concentration between the NiTi and StSt groups in distant organs. The FESEM assessment showed surface corrosion changes to be more evident in the StSt implants. On the basis of this study, the biocompatibility of NiTi seems to be similar to or better than that of stainless steel or Ti-6Al-4V alloy. NiTi appears to be suitable for further use as a biomaterial, because its biocompatibility is good. When NiTi is intended to be used in long-term implants, optimal surface treatment must consider.

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15

Tan, Geraldine. "Thermomechanical behaviour of NiTi." University of Western Australia. School of Mechanical Engineering, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0111.

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[Truncated abstract] The study of NiTi shape memory alloys, although comprehensive and diverse, still encounters numerous uncertainties and misunderstandings that often jeopardise the effective use of these alloys in various applications. One such key area is the understanding of the micromechanics and thermodynamics of the deformation mechanisms, such that their deformation behaviour can be accurately predicted and modelled. Furthermore, most research involves polycrystalline NiTi of varying compositions and processing history, both of which complicate and damage the internal structure of the matrix even before deformation. This work aims to study the micromechanisms of deformation of near-equiatomic NiTi alloys, both in polycrystalline and single crystal forms, with particular attention given to the commonly observed phenomena of Luders-like deformation behaviour and deformation induced martensite stabilisation. This work was carried out in three sections. Firstly, the tensile deformation of polycrystalline NiTi samples via martensite reorientation and stress-induced martensitic transformations was carried out. The samples were deformed to various stages of deformation and then thermally cycled to study the thermomechanical response to deformation as a means to explore the various mechanisms of deformation. Next, the deformation and post-deformation transformation behaviour of NiTi single crystals were studied to verify the effect of grain boundaries and other hypotheses raised regarding the deformation mechanisms. The single crystal samples were deformed along three low-index axial orientations. Finally, microscopic analysis was carried out on as-annealed and the deformed polycrystal and single crystal samples by means of transmission electron microscopy. The microstructural analyses accompanied the thermodynamic study and provided evidences to support various hypotheses

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16

Aydogmus, Tarik. "Processing And Characterization Of Porous Titanium Nickel Shape Memory Alloys." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612232/index.pdf.

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Porous TiNi alloys (Ti-50.4 at. %Ni and Ti-50.6 at. %Ni) with porosities in the range 21%-81% were prepared successfully applying a new powder metallurgy fabrication route in which magnesium was used as space holder resulting in either single austenite phase or a mixture of austenite and martensite phases dictated by the composition of the starting prealloyed powders but entirely free from secondary brittle intermetallics, oxides, nitrides and carbonitrides. Magnesium vapor do not only prevents secondary phase formation and contamination but also provides higher temperature sintering opportunity preventing liquid phase formation at the eutectic temperature, 1118 °
C resulting from Ni enrichment due to oxidation. By two step sintering processing (holding the sample at 1100 °
C for 30 minutes and subsequently sintering at temperatures higher than the eutectic temperature, 1118 °
C) magnesium may allow sintering probably up to the melting point of TiNi. The processed alloys exhibited interconnected (partially or completely depending on porosity content) open macro-pores spherical in shape and irregular micro-pores in the cell walls resulting from incomplete sintering. It has been found that porosity content of the foams have no influence on the phase transformation temperatures while deformation and oxidation are severely influential. Porous TiNi alloys displayed excellent superelasticity and shape memory behavior. Space holder technique seems to be a promising method for production of porous TiNi alloys. Desired porosity level, pore shape and accordingly mechanical properties were found to be easily adjustable.

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17

Cheung, Shun-pan Gary. "Low-cycle fatigue of nickel-titanium rotary root-canal instruments /." View the Table of Contents & Abstract, 2006. http://sunzi.lib.hku.hk/hkuto/record/B36666671.

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18

Cheung, Shun-pan Gary, and 張順彬. "Low-cycle fatigue of nickel-titanium rotary root-canal instruments." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B45015533.

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19

Igharo, M. "The characteristics of titanium-nickel alloys produced by powder technology." Thesis, Open University, 1987. http://oro.open.ac.uk/54610/.

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A range of titanium-nickel alloys near the equiatomic composition have been processed by cold compaction and vacuum sintering. The effects of compaction pressure, sintering temperature and powder particle size on dimensional changes and densities of sintered compacts are presented. The influence of composition and heat treatment on micro hardness and transformation temperature (M_s) is described. During sintering, anisotropy of dimensional change occurs, with expansion in the radial and contraction in the axial direction of cylindrical compacts. Greater porosity is found in the sintered samples compared to that in the as-pressed condition. It is proposed that these observations are connected with the dissimilar interdiffusion rates of Ti and Ni, the segregation of powder particles in the green compacts and the occurrence of a transient liquid phase during sintering above 955°C. Subsequent hot isostatic pressing of the sintered material allows densification to near full density. The transformation temperatures and hardness of TiNi alloys containing excess amounts of nickel (> 51 at -% Ni) are sensitive to cooling rate after solid state heat treatment, which is in contrast with samples of the exact equiatomic composition. This phenomenon has been related to the decrease in the homogeneity range of TiNi compound with temperature, resulting in either the formation of second phase precipitates in the slow cooled samples or the production of a supersaturated structure in water quenched material. The pressed and sintered specimens display a well defined shape memory behaviour. The extent of shape recovery observed, following deformation and heating through the reverse transformation range, is explained in terms of the volume of pores in the sintered compacts. Ribbons of equiatomic TiNi alloy have been rapidly solidified by the chill block melt spinning technique under an argon atmosphere. The effects of rapid solidification processing and subsequent heat treatments on the transformation behaviour are presented. The crystal structures at room temperature have been analysed by X-ray powder diffraction and thin foil transmission electron microscopy. Some of the ribbons have been chopped and ball milled to produce prealloyed particulate from which compacts have been prepared by cold compaction followed by vacuum sintering. The consolidation response of the prealloyed powder is compared with that of elemental blends. The grain size of the rapidly solidified material is found to beat least an order of magnitude smaller than those observed in wrought specimens. The _s temperature of TiNi alloy is depressed by rapid solidification processing, thus allowing the R-phase to be observed in addition to the high temperature parent phase. This depression has been correlated with the fine grain structure of the spun ribbon. Sintering temperatures in excess of those employed for elemental blends are required for the prealloyed particles. This is related to the dominant effect of the alloy formation energy in elemental powders sample. However, while the volume of porosity increases with sintering temperature in elemental mixture compacts, densification takes place in the case of RS prealloyed specimens. In spite of the need for a higher sintering temperature for RS prealloyed compacts,the resulting grain size is smaller.

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20

Patil, Amit k. "ADVANCED PROCESSING OF NICKEL-TITANIUM-GRAPHITE BASED METAL MATRIX COMPOSITES." Cleveland State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=csu1560298763233401.

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21

Chrzanowski, Wojciech. "Engineering surface properties of nickel-titanium alloy for improved osteointegration." Praca habilitacyjna, Wydawnictwo Politechniki Śląskiej, 2012. https://delibra.bg.polsl.pl/dlibra/docmetadata?showContent=true&id=19514.

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22

Fort, Vincent J. "Simulations of the superelastic behavior of nickel-titanium shape memory alloy." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/17388.

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23

Khalil, Heidi F. "Changes in the mechanical behavior of Nitinol following variations of heat treatment duration and temperature." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31852.

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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2010.
Committee Chair: Gall, Kenneth; Committee Member: McDowell, David; Committee Member: Thadhani, Naresh. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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24

Longela, Makusudi Simon. "The development of an artificial hand using nickel-titanium as actuators." Thesis, Cape Peninsula University of Technology, 2013. http://hdl.handle.net/20.500.11838/2229.

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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2013.
This thesis outlines a proposed mechanical design, prototyping and testing of a five fingered artificial hand made of 15 articulated joints actuated by Shape Memory Alloys (SMAs) mimicking muscular functions. SMAs Artificial muscles were incorporated in the forearm and artificial tendons made of nylon wires passing through a hollow palm transmit the pulling force to bend the fingers. Torsion springs set in each joint of the fingers create enough restoring force to straighten the finger when the actuators are disengaged. Nickel-Titanium (NiTi) wires were intrinsically embedded within the hand structure allowing significant movements mimicking human hand-like gestures. A control box made of switches connected to the artificial hand helps to control each gesture. A modular approach was taken in the design to facilitate the manufacture and assembly processes. Nickel-Titanium wires were used as actuators to perform the artificial muscle functions by changing their crystallographic structures due to Joule's heating. Rapid prototyping techniques were employed to manufacture the hand in ABS plastic.

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25

Bowers, Matthew. "Characterization of Transformation-Induced Defects in Nickel Titanium Shape Memory Alloys." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1417649766.

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26

Nirudhoddi, Bhuvi Swarna Lalitha. "Impact Welding and Impulse Shape Calibration of Nickel and Titanium Alloys." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1566161607171927.

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27

Fessenden, Sean D. "Torsional Testing of Race, K3 and Profile Nickel Titanium Endodontic Files." VCU Scholars Compass, 2004. http://scholarscompass.vcu.edu/etd/1012.

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Rotary endodontic instruments have different cross sectional designs that may effect their resistance to torsional stress. The purpose of this study is to evaluate the static torsional properties of two nickel titanium files that have recently been introduced for use in endodontics and compare them to the same size Profile instruments. Ten new files of each brand and size were tested. The files tested were: RaCe 25 tip 0.02, 0.04, 0.06 taper, K3 and Profile 25 and 40 tip in 0.02, 0.04 and 0.06 taper. The diameter of each file was measured at 3mm from tip. The last three millimeters of the working area of the file was grasped with a non-rotating stainless steel chuck and the handle was held in freely rotating chuck. Torque was applied with the Instron Universal Tester in a counter-clockwise direction to simulate the direction of torque encountered clinically. The crosshead speed was set to produce 2 rotations per minute until fracture occurred. The maximum torque achieved and the rotations to fracture were recorded. A multi-way ANOVA of rotations revealed that RaCe 25-0.02 exhibited significantly less rotations to fracture than Profile and K3 of the same size (p<0.0001). RaCe 25 tip exhibited lower maximum torque in all tapers than corresponding K3 and Profile instruments. The mean diameter was significantly smaller for the RaCe files. In this study the RaCe file series exhibited lower values for maximum torque and rotations to fracture. These results should be taken into account while using these files clinically, however further testing is indicated.

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28

Chalker, Paul R. "The oxidation of nickel and titanium studied by XPS and XAES." Thesis, University of Liverpool, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371219.

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29

Xu, Xiao. "Shock-consolidation and reaction synthesis of NiTi intermetallic." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/19076.

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30

McCarty, David Hughes Mary Leigh. "Durability of nitinol for structural applications." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Summer/Theses/MCCARTY_DAVID_39.pdf.

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31

Alapati, Satish B. "An investigation of phase transformation mechanisms for nickel-titanium rotary endodontic instruments." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1140186903.

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32

Mogonye, Jon-Erik. "Solid Lubrication Mechanisms in Laser Deposited Nickel-titanium-carbon Metal Matrix Composites." Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc271864/.

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A Ni/TiC/C metal matrix composite (MMC) has been processed using the laser engineered net shaping (LENS) process from commercially available powders with a Ni-3Ti-20C (atomic %) composition. This processing route produces the in-situ formation of homogeneously distributed eutectic and primary titanium carbide and graphite precipitates throughout the Ni matrix. The composite exhibits promising tribological properties when tested in dry sliding conditions with a low steady state coefficient of friction (CoF) of ~0.1 and lower wear rates in comparison to LENS deposited pure Ni. The as deposited and tribologically worn composite has been characterized using Auger electron spectroscopy, scanning electron microscopy (SEM), X-ray diffraction, high resolution transmission electron microscopy (HRTEM) with energy dispersive spectroscopy (EDS), dual beam focused ion beam SEM (FIB/SEM) serial sectioning and Vickers micro-hardness testing. The evolution of subsurface stress states and precipitate motion during repeated sliding contact has been investigated using finite element analysis (FEA). The results of FIB/SEM serial sectioning, HRTEM, and Auger electron spectroscopy in conjunction with FEA simulations reveal that the improved tribological behavior is due to the in-situ formation of a low interfacial shear strength amorphous carbon tribofilm that is extruded to the surface via refined Ni grain boundaries.

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33

Campbell, Les. "Effect of fatigue on torsional failure of nickel-titanium controlled memory instruments." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44903.

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Abstract Introduction: This study was undertaken to understand how fatigue affects the torsional properties of both traditional nickel-titanium (NiTi) and nickel-titanium controlled memory (CM) files. Methods: Typhoon (TYP) 25.04 and 40.04 rotary files, in both NiTi and CM, were tested using a three-point bending apparatus to obtain the mean number of cycles to failure (mNCF). New files were precycled to four conditions (i.e., 0%, 25%, 50%, and 75% of the mNCF) before torsional resistance tests were performed. Each file was exposed to torsional stress until failure, and at that point the torque and distortion angles were measured. The fracture surface of each fragment was examined with a scanning electron microscope. Results: The TYP CM files yielded a seven-fold improvement in mNCF over the TYP NiTi files (P ≤ 0.05). In both file sizes there was no difference in torque between the CM files and the conventional Ni-Ti files (P > 0.05). The torque of the size 40.04 files was significantly higher than the torque of the size 25/.04 files (P ≤ 0.05). In the 40.04 TYP files group, the 75% precycling group had a significantly lower torque to failure than the no precycling group (P ≤ 0.05). The CM files of both sizes had significantly higher distortion angles than the Ni-Ti files of both sizes (P ≤ 0.05). The 40.04 TYP CM files that were not precycled showed a significantly higher distortion angle than the precycled groups. The fractured files in the precycling groups showed the typical pattern of torsional failure. Conclusions: Cyclic fatigue has an effect on torsional fracture resistance of TYP and TYP CM files on size 40.04. TYP CM files displayed a similar torque value to TYP files but rotated a greater angle before fracture in both preloading and no preloading groups.

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Lee, Wing-cheung, and 李永祥. "Functional coatings on Ti-6A1-4V and NiTi shape memory alloy for medical applications." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B4715052X.

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Due to its excellent biocompatibility and mechanical properties, Ti-6Al-4V alloy has been extensively used in the medical field, especially as a material for hard tissue replacement. Owing to the unique shape memory and superelastic properties, NiTi shape memory alloy (SMA, with 50.8 at.% of Ni) has been investigated for load-bearing applications in orthopedics and dentistry. Since the longevity of current metal implants is approximately 10 to 15 years, many patients need to have revision surgeries in their lifetime. Therefore, there is great interest in the long-term stability, biocompatibility, bioactivity and other properties of Ti-6Al-4V and NiTi SMA implants. Implant-associated infections also pose serious threat to the success of metal implants. The goal of this project was to investigate several low-temperature surface modification techniques, including anodization and electrochemical deposition, and formulate coatings for potential clinical applications. Accordingly, several types of coatings were synthesized on Ti-6Al-4V and NiTi SMA substrates. Various aspects of the coatings, such as morphology, chemical composition, crystallinity, phase and bioactivity, were analyzed. Firstly, a systematic study on the formation of titania nanotubes on Ti-6Al-4V by anodization was performed. Anodizing voltage and time were varied for comparisons. A dense and compact titania nanotube layer was synthesized on Ti-6Al-4V by anodizing at 25 V for 20 min. The titania nanotubes formed were rutile. After annealing at 500oC for 1 h, the titania nanotubes became anatase. The anatase phase exhibited better wettability than the rutile phase. Secondly, dense and compact apatite coatings were formed on NiTi SMA samples through electrochemical deposition using mainly double-strength simulated body fluid (2SBF) as the electrolyte. The deposition conditions were varied and apatite coating characteristics studied. With the inclusion of collagen molecules (0.1 mg/ml) in the electrolyte (2SBFC), apatite/collagen composite coatings were fabricated. Collagen fibrils were not only observed on the surface of composite coatings but also were embedded inside in the coatings and at the coating-substrate interface. Results obtained from transmission electron microscopic and X-ray diffraction analyses showed that the apatite crystals in apatite coatings and apatite/collagen composite coatings were calcium-deficient carbonated hydroxyapatite. Apatite/collagen composite coatings exhibited excellent hydrophilicity, whereas apatite coatings displayed hydrophobic surfaces. Finally, gentamicin-loaded, tobramycin-loaded, and vancomycin-loaded apatite coatings and apatite/collagen composite coatings were synthesized on NiTi SMA samples through electrochemical deposition using different drug concentrations in the electrolytes. A comparative study of apatite coatings and apatite/collagen composite coatings as drug delivery vehicles were conducted. Different aspects of antibiotic-loaded coatings (surface characteristics, chemical composition, wettability, etc.) and in vitro release behaviour were investigated. The antibiotics were physically embedded in coatings during coating formation. Upon sample soaking in phosphate-buffered saline (PBS), the release profiles established for antibiotic-loaded coatings demonstrated different levels of initial burst release and subsequent steady release characteristics. Apatite coatings and apatite/collagen coatings displayed preferential incorporation of specific antibiotics. For instance, apatite/collagen coatings showed better vancomycin incorporation than apatite coatings and the incorporation of vancomycin was better than tobramycin for apatite/collagen coatings. Apatite coatings demonstrated better tobramycin incorporation than apatite/collagen composite coatings.
published_or_final_version
Mechanical Engineering
Master
Master of Philosophy

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Adharapurapu, Raghavendra R. "Phase transformations in nickel-rich nickel-titanium alloys influence of strain-rate, temperature, thermomechanical treatment and nickel composition on the shape memory and superelastic characteristics /." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3262183.

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Thesis (Ph. D.)--University of California, San Diego, 2007.
Title from first page of PDF file (viewed July 10, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.

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36

Bloss, Matthew C. "Ultrasonic metal welding the weldability of stainless steel, titanium, and nickel-based superalloys /." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1198168491.

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37

Gibson, Myles. "The Heat Treatment of Nickel Titanium - An investigation Using Taguchi's Method of Optimisation." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-28769.

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38

Botterill, Nicholas William. "Deposition and characterisation of thin film nickel-titanium shape memory alloys for microactuation." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246420.

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39

Kitchens, George Gray Jr. "The Effect of Operational Speed on the Fracture of Nickel Titanium Rotary Instruments." VCU Scholars Compass, 2006. http://scholarscompass.vcu.edu/etd_retro/66.

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Numerous nickel titanium rotary file systems have been introduced in recent years. The recommended speed at which these files are to be operated varies widely between manufacturers. The purpose of this study was to test the number of rotations to fracture of NiTi rotary files when operated at different speeds and at different angles. Sixty size 25 Profile® nickel titanium rotary files were tested, thirty 0.04 and thirty 0.06 taper. Files were operated at speeds of 350 or 600 rpm and at angles of 25°, 28°, and 33.5°. The time to fracture was recorded and the numbers of rotations to fracture were calculated. The data was analyzed using a two-way ANOVA, and post hoc Tukey-Kramer multiple-comparison test with alpha = .001. The results show a significant difference in the number of rotations fracture according to taper and angle. Files of .06 taper fractured more readily than files of .04 taper as the speed increased, and the time to fracture decreased for both tapers as the angle increased. No significant difference was produced by the speed at which the files were operated. The number of rotations until fracture of NiTi rotary files is not related to the operational speed.

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Lloyd, Matthew Warren. "A Comparison of Flexural Fracture of Three Different Nickel-Titanium Rotary File Systems." VCU Scholars Compass, 2007. http://scholarscompass.vcu.edu/etd/708.

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The purpose of this study was to compare the number of rotations to failure of three different rotary file systems. ProFile, Sequence, and Liberator files in sizes 25 and 40 with 0.04 taper were divided into groups of five and rotated against a grooved metal block mounted to a Universal testing machine at 31 and 34 degrees. Each file was rotated at 300 rpm until fracture occurred. The number of rotations to fracture were calculated. Use of a three-way ANOVA and Tukey's HSD multiple comparison tests revealed significant differences for the angle of deflection, size, and type of file. An increased angle of deflection resulted in a decreased number of rotations to failure for all three file types. An increased size of file also resulted in a decreased number of rotations to failure in all the groups. Liberator and Sequence files required fewer rotations to failure than ProFiles in all groups tested except the size 25 files rotated at the less severe angle. ProFiles appear to be more resistant to flexural fracture than Liberator and Sequence files unless the files are of smaller size with a less severe curvature. Care should be taken to limit the number of uses when using larger size files, especially Liberator and Sequence files, around severe curvatures.

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41

Gopagoni, Sundeep. "Microstructure Evolution in Laser Deposited Nickel-Titanium-Carbon in situ Metal Matrix Composite." Thesis, University of North Texas, 2010. https://digital.library.unt.edu/ark:/67531/metadc33154/.

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Ni/TiC metal matrix composites have been processed using the laser engineered net shaping (LENS) process. As nickel does not form an equilibrium carbide phase, addition of a strong carbide former in the form of titanium reinforces the nickel matrix resulting in a promising hybrid material for both surface engineering as well as high temperature structural applications. Changing the relative amounts of titanium and carbon in the nickel matrix, relatively low volume fraction of refined homogeneously distributed carbide precipitates, formation of in-situ carbide precipitates and the microstructural changes are investigated. The composites have been characterized in detail using x-ray diffraction, scanning electron microscopy (including energy dispersive spectroscopy (XEDS) mapping and electron backscatter diffraction (EBSD)), Auger electron spectroscopy, and transmission (including high resolution) electron microscopy. Both primary and eutectic titanium carbides, observed in this composite, exhibited the fcc-TiC structure (NaCl-type). Details of the orientation relationship between Ni and TiC have been studied using SEM-EBSD and high resolution TEM. The results of micro-hardness and tribology tests indicate that these composites have a relatively high hardness and a steady-state friction coefficient of ~0.5, both of which are improvements in comparison to LENS deposited pure Ni.

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Braña, Paula. "Crystallization characteristics of Ni-Ti metallic glasses." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66213.

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Fung, Cheung Kwan. "Thermal mechanical behaviour of NiTi shape memory alloy." access abstract and table of contents access full-text, 2004. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21174076a.pdf.

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Thesis (M.Sc.)--City University of Hong Kong, 2004.
At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Aug. 31, 2006) Includes bibliographical references.

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44

Zhao, Ying. "Design of energy absorbing materials and composite structures based on porous shape memory alloys (SE) /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/7148.

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45

Heck, Alexandre Roberto. "Avaliação da alteração morfologica do canal radicular apos o preparo com tres tecnicas de instrumentação e do tempo gasto para sua execução." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/289821.

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Orientador: Luiz Valdrighi
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-04T03:57:00Z (GMT). No. of bitstreams: 1 Heck_AlexandreRoberto_D.pdf: 1868066 bytes, checksum: b350ae21133640d625c8404b77a05dd4 (MD5) Previous issue date: 2005
Resumo: O presente estudo teve como objetivo avaliar, comparativamente, em 45 raízes mesiais de molares inferiores, totalizando 90 canais, divididos em 3 grupos, o tempo, a média da área desgastada e a espessura média da parede dentinária remanescente na distal da raiz mesial, antes e após o emprego da técnica escalonada, da técnica híbrida modificada pela FOP-Unicamp, e da técnica rotatória Easy Endo-Multitaper. Foram realizados cortes transversais a 3 e 8 mm do ápice denominados segmento apical e cervical. As imagens dos segmentos transversais foram obtidas, antes e após o preparo dos canais, com uma câmara digital acoplada a uma lupa estereoscópica. As medidas das áreas dos canais e as medidas das espessuras das paredes distais da raiz foram registradas por meio do ¿software¿ Imagelab/98. Estas medidas, bem como a variável tempo e a ampliação das áreas foram analisados estatisticamente. Os resultados mostraram diferenças significativas no segmento cervical entre a técnica manual e as técnicas híbrida e rotatória. A ampliação das áreas, no segmento apical, foi significativamente maior na técnica manual, e, no segmento cervical, maior para as técnicas híbrida e rotatória. A espessura da parede distal da raiz mesial mostrou-se significativamente menor após a realização da instrumentação sem diferença entre as técnicas. As técnicas híbrida e rotatória foram significativamente mais rápidas que a técnica manual
Abstract: The present study was aimed to evaluate comparatively, in mesial roots of lower molars, before and after the use of the ¿step-back¿ manual technique, the hybrid technique modified by FOP-Unicamp, and the Easy Endo-Multitaper rotary technique, the time, the mean of the trimmed area and the mean of the thickness of the remained dentine wall in the distal region of the mesial root. Transversal sections were made 3 to 8 mm of the apical terminus, named apical and coronal sections. The images of these sections were captured by stereoscopic magnification lens with a video camera and stored in a computer. Then, the measurements of the root canal area and a linear measurement were carried out using a ImageLab software. The before and after measurements, as well as the increments, were statistically analized. The results showed significant differences in the coronal segment when comparing manual to hybrid and rotary techniques. The increment was significantly larger in the apical segment using the manual technique. In the coronal segment, the increment was larger using the hybrid and rotary techniques. The distance between the distal wall and the mesial root was significantly less after instrumentation, not showing differences among the techniques. The hybrid and rotary techniques were significantly less time-consuming than the manual technique
Doutorado
Endodontia
Doutor em Clínica Odontológica

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46

Kwak, J. E. (Jan Erik). "The behaviour of titanium, stainless steel and copper-nickel alloys as plasma torch cathodes." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26396.

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Cathode erosion continues to be a problem hindering the widespread application of plasma technology. In this work, cathode erosion for various materials was studied for arcs operating in argon, nitrogen and hydrogen, using a magnetically rotated arc.
Titanium and stainless steel were found to give extremely low erosion rates in argon (0.2 and 0.3 $ mu$g/C respectively). Cupro-nickels were shown to be suitable for nitrogen and hydrogen plasmas. The slope of hydrogen solubility vs. temperature in the cathode material was found to be important in determining hydrogen plasma erosion characteristics. When the plasma gas has a high solubility in the cathode material, or can react with the cathode, a negative erosion rate may result. When gas solubility in the cathode is low, oxide stability and mode of electron emission may govern erosion rate. A high gas solubility in the cathode material, as with hydrogen, can result in mechanical erosion due to micro-explosions in the cathode surface.

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47

Tomsic, Albert L. "The effect of multiple usages of nickel-titanium rotary endodontic files on cutting efficiency." Morgantown, W. Va. : [West Virginia University Libraries], 2009. http://hdl.handle.net/10450/10032.

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Thesis (M.S.)--West Virginia University, 2009.
Title from document title page. Document formatted into pages; contains viii, 44 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 40-43).

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48

Lewis, Matthew Tyson. "Nanoindentation of Annealed and As-Sputtered Thin Films of Nickel Titanium Shape Memory Alloys." DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/395.

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The bottom-up processing techniques used for making Microelectromechanical systems (MEMS) devices can produce material properties different from bulk processing. The material properties must be evaluated with the process parameters used and for changes in the process parameters. The mechanical properties are needed to design MEMS devices. A material of interest for MEMS devices is nickel titanium (NiTi) shape memory alloy (SMA) because of the high work output (~107 J/m3). This thesis will focus on the fabrication of thin film NiTi by DC magnetron sputtering deposition and testing mechanical properties of the fabricated films by nanoindentation. Thin film NiTi SMA was successfully created by DC magnetron sputtering deposition and high vacuum annealing in the Microfabrication Laboratory at California Polytechnic State University – San Luis Obispo. Characterization of the thin film by nanoindentation produced an elastic modulus of the thin film NiTi SMA with the developed processing parameters was 67.9 GPa with a hardness of 2.1 GPa. The measured thin film NiTi elastic modulus was greater than bulk NiTi of 40 GPa because of the residual stress from the deposition process. The shape memory effect was evaluated at the nanometer scale by measuring the nanoindents before and after thermally inducing a phase transformation. A maximum indentation depth recovery of 58% was measured upon the heat induced martensitic phase transformation. The low recovery was attributed to the high strain of 8% induced by the Berkovich tip. The effects of deposition power on the NiTi as-sputtered film stress, elastic modulus, hardness, and electrical conductivity were evaluated. At the highest sputtering deposition power of 450 Watts, an elastic modulus of 186 GPa with a hardness of 8.3 GPa was measured by nanoindentation. An increase in deposition power increased the residual film compressive stress, elastic modulus, and hardness while the electrical resistivity increased. The mechanisms for the measured properties are discussed in this thesis.

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49

Yang, Eugenia You Yea. "Comparison of two methodologies for testing cyclic fatigue resistance of nickel-titanium rotary files." Thesis, Boston University, 2015. https://hdl.handle.net/2144/37825.

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Thesis (MSD) --Boston University, Henry M. Goldman School of Dental Medicine, 2015 (Department of Endodontics).
Includes bibliography: leaves 69-74.
Nickel titanium (NiTi) rotary files have become an important adjunct to endodontic treatment of the root canal system. However, despite the many advantages, Ni-Ti rotary files have a risk of unexpected fracture without any visible signs of previous permanent deformation. A wide range of methodologies have been developed over the years to test cyclic fatigue; yet to date, there is no specification or international standard for cyclic fatigue testing. The aim of this study was to compare the effect of the stainless steel and the glass tube method on the cyclic fatigue resistance of K3[R], K3xF[R], Vortex[R], Vortex Blue[R], and PROTAPER NEXT[R] NiTi rotary files. Material and Methods: A total of 450 new NiTi rotary fies were tested in this study. These files were divided equally into two groups: one group was subjected to a stainless steel (SS) artificial grooved canal model, and the other group employed the glass tube (GT) model (n=225). Three file sizes, 20.06, 25.06 and 30.06, were selected for the K3[R], K3xF[R], Vortex[R], and Vortex Blue[R] systems; and X1, X2 and X3 was selected from the PROTAPER NEXT[R] system. The files were subjected to an angle of curvature of 60 degrees with a 5mm radius of curvature at 300 rpm for both devices. The number of cycles to failure (NCF) and length of fracture file piece were recorded and statistically analyzed. Results: Significant differences were found between the stainless steel and glass tube testing methodologies; NCF ranged from 325 - 1147 for SS and 412 - 1901 for GT. Both methodologies showed a similar pattern of relationship between file comparisons with the GT method showing greater significant differences among file types. Vortex Blue[R] was the most resistant to cyclic fatigue, and K3[R] system was the least resistant to cyclic fatigue regardless of the testing methodology. The Vortex Blue[R] 20.06 file had the highest cyclic fatigue resistance with a mean NCF of l 147 [plus or minus] 184.3 for SS and 1530.3 [plus or minus] 258 for GT. ProtaperNext[R] X2 (325 [plus or minus] 48.3) and K3[R] 30.06 (412 [plus or minus] 93.4) files had the lowest cyclic fatigue life in the SS and GT method respectively. With the exception of Protaper Next[R], within the same file systems, there is an inverse relationship in regards to tip sizes and number of cycles to failure. Conclusion: The glass tube method is a more accurate measure of cyclic fatigue resistance than the stainless steel method for cyclic fatigue. Vortex Blue[R] and smaller tip sized files performed best in this study.

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Achuthankutty, Ajith. "Deposition Kinetics of Titanium and Zirconium Diffusion Coatings on Nickel Microwires via Pack Cementation." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1592133155467387.

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