Mechanical behavior and clinical application of nickel-titanium closed-coil springs under different stress levels and mechanical loading cycles.

Science.gov (United States)

Wichelhaus, Andrea; Brauchli, Lorenz; Ball, Judith; Mertmann, Matthias

2010-05-01

The main advantage of superelastic nickel-titanium (NiTi) products is their unique characteristic of force plateaus, which allow for clinically precise control of the force. The aims of this study were to define the mechanical characteristics of several currently available closed-coil retraction springs and to compare these products. A universal test frame was used to acquire force-deflection diagrams of 24 NiTi closed-coil springs at body temperature. Data analysis was performed with the superelastic algorithm. Also, the influence of temperature cycles and mechanical microcycles simulating ingestion of different foods and mastication, respectively, were considered. Mechanical testing showed significant differences between the various spring types (ANOVA, mechanical properties of the springs: strong superelasticity without bias stress, weak superelasticity without bias stress, strong superelasticity with bias stress, and weak superelasticity with bias stress. In sliding mechanics, the strongly superelastic closed-coil springs with preactivation are recommended. In addition, we found that the oral environment seems to have only a minor influence on their mechanical properties. Copyright (c) 2010 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Temperature-modulated DSC provides new insight about nickel-titanium wire transformations.

Science.gov (United States)

Brantley, William A; Iijima, Masahiro; Grentzer, Thomas H

2003-10-01

Differential scanning calorimetry (DSC) is a well-known method for investigating phase transformations in nickel-titanium orthodontic wires; the microstructural phases and phase transformations in these wires have central importance for their clinical performance. The purpose of this study was to use the more recently developed technique of temperature-modulated DSC (TMDSC) to gain insight into transformations in 3 nickel-titanium orthodontic wires: Neo Sentalloy (GAC International, Islandia, NY), 35 degrees C Copper Ni-Ti (Ormco, Glendora, Calif) and Nitinol SE (3M Unitek, Monrovia, Calif). In the oral environment, the first 2 superelastic wires have shape memory, and the third wire has superelastic behavior but not shape memory. All wires had cross-section dimensions of 0.016 x 0.022 in. Archwires in the as-received condition and after bending 135 degrees were cut into 5 or 6 segments for test specimens. TMDSC analyses (Model 2910 DSC, TA Instruments, Wilmington, Del) were conducted between -125 degrees C and 100 degrees C, using a linear heating and cooling rate of 2 degrees C per min, an oscillation amplitude of 0.318 degrees C with a period of 60 seconds, and helium as the purge gas. For all 3 wire alloys, strong low-temperature martensitic transformations, resolved on the nonreversing heat-flow curves, were not present on the reversing heat-flow curves, and bending appeared to increase the enthalpy change for these peaks in some cases. For Neo Sentalloy, TMDSC showed that transformation between martensitic and austenitic nickel-titanium, suggested as occurring directly in the forward and reverse directions by conventional DSC, was instead a 2-step process involving the R-phase. Two-step transformations in the forward and reverse directions were also found for 35 degrees C Copper Ni-Ti and Nitinol SE. The TMDSC results show that structural transformations in these wires are complex. Some possible clinical implications of these observations are discussed.

Evolution of flexural rigidity according to the cross-sectional dimension of a superelastic nickel titanium orthodontic wire.

Science.gov (United States)

Garrec, Pascal; Tavernier, Bruno; Jordan, Laurence

2005-08-01

The choice of the most suitable orthodontic wire for each stage of treatment requires estimation of the forces generated. In theory, the selection of wire sequences should initially utilize a lower flexural rigidity; thus clinicians use smaller round cross-sectional dimension wires to generate lighter forces during the preliminary alignment stage. This assessment is true for conventional alloys, but not necessarily for superelastic nickel titanium (NiTi). In this case, the flexural rigidity dependence on cross-sectional dimension differs from the linear elasticity prediction because of the martensitic transformation process. It decreases with increasing deflection and this phenomenon is accentuated in the unloading process. This behaviour should lead us to consider differently the biomechanical approach to orthodontic treatment. The present study compared bending in 10 archwires made from NiTi orthodontics alloy of two cross-sectional dimensions. The results were based on microstructural and mechanical investigations. With conventional alloys, the flexural rigidity was constant for each wire and increased largely with the cross-sectional dimension for the same strain. With NiTi alloys, the flexural rigidity is not constant and the influence of size was not as important as it should be. This result can be explained by the non-constant elastic modulus during the martensite transformation process. Thus, in some cases, treatment can begin with full-size (rectangular) wires that nearly fill the bracket slot with a force application deemed to be physiologically desirable for tooth movement and compatible with patient comfort.

In vitro biocompatibility of nickel-titanium esthetic orthodontic archwires.

Science.gov (United States)

Rongo, Roberto; Valletta, Rosa; Bucci, Rosaria; Rivieccio, Virginia; Galeotti, Angela; Michelotti, Ambrosina; D'Antò, Vincenzo

2016-09-01

To investigate the cytotoxicity of nickel-titanium (NiTi) esthetic orthodontic archwires with different surface coatings. Three fully coated, tooth-colored NiTi wires (BioCosmetic, Titanol Cosmetic, EverWhite), two ion-implanted wires (TMA Purple, Sentalloy High Aesthetic), five uncoated NiTi wires (BioStarter, BioTorque, Titanol Superelastic, Memory Wire Superelastic, and Sentalloy), one β-titanium wire (TMA), and one stainless steel wire (Stainless Steel) were considered for this study. The wire samples were placed at 37°C in airtight test tubes containing Dulbecco's Modified Eagle's Medium (0.1 mg/mL) for 1, 7, 14, and 30 days. The cell viability of human gingival fibroblasts (HGFs) cultured with this medium was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Data were analyzed by a two-way analysis of variance (α  =  .05). The highest cytotoxic effect was reached on day 30 for all samples. The archwires exhibited a cytotoxicity on HGFs ranging from "none" to "slight," with the exception of the BioTorque, which resulted in moderate cytotoxicity on day 30. Significant differences were found between esthetic archwires and their uncoated pairs only for BioCosmetic (P  =  .001) and EverWhite (P < .001). Under the experimental conditions, all of the NiTi esthetic archwires resulted in slight cytotoxicity, as did the respective uncoated wires. For this reason their clinical use may be considered to have similar risks to the uncoated archwires.

Finite element modeling of superelastic nickel-titanium orthodontic wires.

Science.gov (United States)

Naceur, Ines Ben; Charfi, Amin; Bouraoui, Tarak; Elleuch, Khaled

2014-11-28

Thanks to its good corrosion resistance and biocompatibility, superelastic Ni–Ti wire alloys have been successfully used in orthodontic treatment. Therefore, it is important to quantify and evaluate the level of orthodontic force applied to the bracket and teeth in order to achieve tooth movement. In this study, three dimensional finite element models with a Gibbs-potential-based-formulation and thermodynamic principles were used. The aim was to evaluate the influence of possible intraoral temperature differences on the forces exerted by NiTi orthodontic arch wires with different cross sectional shapes and sizes. The prediction made by this phenomenological model, for superelastic tensile and bending tests, shows good agreement with the experimental data. A bending test is simulated to study the force variation of an orthodontic NiTi arch wire when it loaded up to the deflection of 3 mm, for this task one half of the arch wire and the 3 adjacent brackets were modeled. The results showed that the stress required for the martensite transformation increases with the increase of cross-sectional dimensions and temperature. Associated with this increase in stress, the plateau of this transformation becomes steeper. In addition, the area of the mechanical hysteresis, measured as the difference between the forces of the upper and lower plateau, increases.

Metallurgical characterization of a new nickel-titanium wire for rotary endodontic instruments.

Science.gov (United States)

Alapati, Satish B; Brantley, William A; Iijima, Masahiro; Clark, William A T; Kovarik, Libor; Buie, Caesar; Liu, Jie; Ben Johnson, William

2009-11-01

A novel thermomechanical processing procedure has been developed that yields a superelastic (SE) nickel-titanium (NiTi) wire (M-Wire) that laboratory testing shows has improved mechanical properties compared with conventional SE austenitic NiTi wires used for manufacture of rotary instruments. The objective of this study was to determine the origin of the improved mechanical properties. Specimens from 2 batches of M-Wire prepared under different processing conditions and from 1 batch of standard-processed SE wire for rotary instruments were examined by scanning transmission electron microscopy, temperature-modulated differential scanning calorimetry, micro-x-ray diffraction, and scanning electron microscopy with x-ray energy-dispersive spectrometric analyses. The processing for M-Wire yields a microstructure containing martensite, that the proportions of NiTi phases depend on processing conditions, and that the microstructure exhibits pronounced evidence of alloy strengthening. The presence of Ti(2)Ni precipitates in both microstructures indicates that M-Wire and the conventional SE wire for rotary instruments are titanium-rich.

Surface and corrosion characteristics of carbon plasma implanted and deposited nickel-titanium alloy

International Nuclear Information System (INIS)

Poon, R.W.Y.; Liu, X.Y.; Chung, C.Y.; Chu, P.K.; Yeung, K.W.K.; Lu, W.W.; Cheung, K.M.C.

2005-01-01

Nickel-titanium shape memory alloys (NiTi) are potentially useful in orthopedic implants on account of their super-elastic and shape memory properties. However, the materials are prone to surface corrosion and the most common problem is out-diffusion of harmful Ni ions from the substrate into body tissues and fluids. In order to improve the corrosion resistance and related surface properties, we used the technique of plasma immersion ion implantation and deposition to deposit an amorphous hydrogenated carbon coating onto NiTi and implant carbon into NiTi. Both the deposited amorphous carbon film and carbon plasma implanted samples exhibit much improved corrosion resistances and surface mechanical properties and possible mechanisms are suggested

Clinical bending of nickel titanium wires

Directory of Open Access Journals (Sweden)

Stephen Chain

2015-01-01

Full Text Available Since the evolution and the involvement of Nickel Titanium wires in the field of Orthodontics. The treatment plan has evolved with the use of low force Nickel Titanium wires. Because of their high springback, low stiffness, they are the key initial wires in leveling and alignment but have poor formability. Since poor formability limits its ability to create variable arch forms thus; limits the form of treatment. We have devised a method to bend the Nickel Titanium wires to help in our inventory but also customized the wire according to the treatment.

X-ray diffraction study of low-temperature phase transformations in nickel-titanium orthodontic wires.

Science.gov (United States)

Iijima, M; Brantley, W A; Guo, W H; Clark, W A T; Yuasa, T; Mizoguchi, I

2008-11-01

Employ conventional X-ray diffraction (XRD) to analyze three clinically important nickel-titanium orthodontic wire alloys over a range of temperatures between 25 and -110 degrees C, for comparison with previous results from temperature-modulated differential scanning calorimetry (TMDSC) studies. The archwires selected were 35 degrees C Copper Ni-Ti (Ormco), Neo Sentalloy (GAC International), and Nitinol SE (3M Unitek). Neo Sentalloy, which exhibits superelastic behavior, is marketed as having shape memory in the oral environment, and Nitinol SE and 35 degrees C Copper Ni-Ti also exhibit superelastic behavior. All archwires had dimensions of 0.016in.x0.022in. (0.41 mm x 0.56 mm). Straight segments cut with a water-cooled diamond saw were placed side-by-side to yield a 1 cm x 1cm test sample of each wire product for XRD analysis (Rint-Ultima(+), Rigaku) over a 2theta range from 30 degrees to 130 degrees and at successive temperatures of 25, -110, -60, -20, 0 and 25 degrees C. The phases revealed by XRD at the different analysis temperatures were in good agreement with those found in previous TMDSC studies of transformations in these alloys, in particular verifying the presence of R-phase at 25 degrees C. Precise comparisons are not possible because of the approximate nature of the transformation temperatures determined by TMDSC and the preferred crystallographic orientation present in the wires. New XRD peaks appear to result from low-temperature transformation in martensite, which a recent transmission electron microscopy (TEM) study has shown to arise from twinning. While XRD is a useful technique to study phases in nickel-titanium orthodontic wires and their transformations as a function of temperature, optimum insight is obtained when XRD analyses are combined with complementary TMDSC and TEM study of the wires.

Effect of clinical use of nickel-titanium springs.

Science.gov (United States)

Magno, Amanda Fahning; Monini, André da Costa; Capela, Marisa Veiga; Martins, Lídia Parsekian; Martins, Renato Parsekian

2015-07-01

Our objectives were to determine whether there are changes on the load deflection rate (L/DP) and the average force (FP) of the superelastic pseudoplateau, and whether permanent deformation is changed in nickel-titanium closed-coil springs (CCSs) after 6 months of clinical use. Twenty-two nickel-titanium CCSs (Sentalloy 100 g; Dentsply GAC, York, Pa) were subjected to tensile mechanical testing at 37°C on activations varying from 3.2 to 16.0 mm before and after 6 months of clinical use. A regression line was fitted over the most horizontal area of the unloading part of the stress-strain graph of every CCS, and its slope was used as L/DP. The FP was determined by the midpoint of the longest segment of the curve that could be fit within the regression line with a R(2) of at least 0.999, and permanent deformation was determined graphically by obtaining the strain value when the measured stress reached zero. The data were analyzed by 3 analyses of variance at 2 levels, with 5% of significance. Time and activation significantly influenced the variables tested (P < 0.001). Time increased the L/DP and permanent deformation but decreased the FP. Activation decreased L/DP, FP, and permanent deformation. Significant interactions between time and activation were detected for FP (P = 0.013) and deformation (P < 0.001). After 6 months of active clinical use, the analyzed springs had a significant but small increase in their L/DP; FP dropped up to 88%, and the CCSs deformed up to 1.26 mm. Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Design of a nitrogen-implanted titanium-based superelastic alloy with optimized properties for biomedical applications

International Nuclear Information System (INIS)

Gordin, D.M.; Busardo, D.; Cimpean, A.; Vasilescu, C.; Höche, D.; Drob, S.I.; Mitran, V.; Cornen, M.; Gloriant, T.

2013-01-01

In this study, a superelastic Ni-free Ti-based biomedical alloy was treated in surface by the implantation of nitrogen ions for the first time. The N-implanted surface was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and secondary ion mass spectroscopy, and the superficial mechanical properties were evaluated by nano-indentation and by ball-on-disk tribological tests. To investigate the biocompatibility, the corrosion resistance of the N-implanted Ti alloy was evaluated in simulated body fluids (SBF) complemented by in-vitro cytocompatibility tests on human fetal osteoblasts. After implantation, surface analysis methods revealed the formation of a titanium-based nitride on the substrate surface. Consequently, an increase in superficial hardness and a significant reduction of friction coefficient were observed compared to the non-implanted sample. Also, a better corrosion resistance and a significant decrease in ion release rates have been obtained. Cell culture experiments indicated that the cytocompatibility of the N-implanted Ti alloy was superior to that of the corresponding non-treated sample. Thus, this new functional N-implanted titanium-based superelastic alloy presents the optimized properties that are required for various medical devices: superelasticity, high superficial mechanical properties, high corrosion resistance and excellent cytocompatibility. - Highlights: • A superelastic Ni-free Ti-based biomedical alloy was treated in surface by implantation of nitrogen ions. • Much higher superficial hardness and wear resistance were obtained. • A clear enhancement of the corrosion resistance in SBF was observed. • In-vitro tests performed on human fetal osteoblasts indicated an excellent level of cytocompatibility

Design of a nitrogen-implanted titanium-based superelastic alloy with optimized properties for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Gordin, D.M. [INSA de Rennes, Laboratoire Chimie-Métallurgie, UMR CNRS 6226 Institut des Sciences Chimiques de Rennes, 20 avenue des Buttes de Coësmes, 35708 Rennes Cedex 7 (France); Busardo, D. [Quertech Ingénierie, 9 rue de la Girafe, 14000 Caen (France); Cimpean, A. [University of Bucharest, Department of Biochemistry and Molecular Biology, Spl. Independentei 91-95, 050095 Bucharest (Romania); Vasilescu, C. [Institute of Physical Chemistry «Ilie Murgulescu» of Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Höche, D. [Institute of Materials Research, Helmholtz-Zentrum Geesthacht -Zentrum für Material- und Küstenforschung GmbH Max-Planck-Straße 1, D-21502 Geesthacht (Germany); Drob, S.I. [Institute of Physical Chemistry «Ilie Murgulescu» of Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Mitran, V. [University of Bucharest, Department of Biochemistry and Molecular Biology, Spl. Independentei 91-95, 050095 Bucharest (Romania); Cornen, M. [INSA de Rennes, Laboratoire Chimie-Métallurgie, UMR CNRS 6226 Institut des Sciences Chimiques de Rennes, 20 avenue des Buttes de Coësmes, 35708 Rennes Cedex 7 (France); Gloriant, T., E-mail: Thierry.Gloriant@insa-rennes.fr [INSA de Rennes, Laboratoire Chimie-Métallurgie, UMR CNRS 6226 Institut des Sciences Chimiques de Rennes, 20 avenue des Buttes de Coësmes, 35708 Rennes Cedex 7 (France)

2013-10-15

In this study, a superelastic Ni-free Ti-based biomedical alloy was treated in surface by the implantation of nitrogen ions for the first time. The N-implanted surface was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and secondary ion mass spectroscopy, and the superficial mechanical properties were evaluated by nano-indentation and by ball-on-disk tribological tests. To investigate the biocompatibility, the corrosion resistance of the N-implanted Ti alloy was evaluated in simulated body fluids (SBF) complemented by in-vitro cytocompatibility tests on human fetal osteoblasts. After implantation, surface analysis methods revealed the formation of a titanium-based nitride on the substrate surface. Consequently, an increase in superficial hardness and a significant reduction of friction coefficient were observed compared to the non-implanted sample. Also, a better corrosion resistance and a significant decrease in ion release rates have been obtained. Cell culture experiments indicated that the cytocompatibility of the N-implanted Ti alloy was superior to that of the corresponding non-treated sample. Thus, this new functional N-implanted titanium-based superelastic alloy presents the optimized properties that are required for various medical devices: superelasticity, high superficial mechanical properties, high corrosion resistance and excellent cytocompatibility. - Highlights: • A superelastic Ni-free Ti-based biomedical alloy was treated in surface by implantation of nitrogen ions. • Much higher superficial hardness and wear resistance were obtained. • A clear enhancement of the corrosion resistance in SBF was observed. • In-vitro tests performed on human fetal osteoblasts indicated an excellent level of cytocompatibility.

Ball bearings comprising nickel-titanium and methods of manufacture thereof

Science.gov (United States)

DellaCorte, Christopher (Inventor); Glennon, Glenn N. (Inventor)

2012-01-01

Disclosed herein is a friction reducing nickel-titanium composition. The nickel-titanium composition includes a first phase that comprises nickel and titanium in an atomic ratio of about 0.45:0.55 to about 0.55:0.45; a second phase that comprises nickel and titanium in an atomic ratio of about 0.70:0.30 to about 0.80:0.20; and a third phase that comprises nickel and titanium in an atomic ratio of about 0.52:0.48 to about 0.62:0.38. A bearing for reducing friction comprising a nickel-titanium composition comprising a first phase that comprises nickel and titanium in an atomic ratio of about 0.45:0.55 to about 0.55:0.45; a second phase that comprises nickel and titanium in an atomic ratio of about 0.70:0.30 to about 0.80:0.20; and a third phase that comprises nickel and titanium in an atomic ratio of about 0.52:0.48 to about 0.62:0.38; where the bearing is free from voids and pinholes.

Mechanodynamical analysis of nickel-titanium alloys for orthodontics application; Analise mecanodinamica de ligas de niquel-titanio para aplicacao ortodontica

Energy Technology Data Exchange (ETDEWEB)

Arruda, Carlos do Canto

2002-07-01

Nickel-titanium alloys may coexist in more than one crystalline structure. There is a high temperature phase, austenite, and a low temperature phase, martensite. The metallurgical basis for the superelasticity and the shape memory effect relies in the ability of these alloys to transform easily from one phase to another. There are three essential factors for the orthodontist to understand nickel-titanium alloys behaviour: stress; deflection; and temperature. These three factors are related to each other by the stress-deflection, stress-temperature and deflection-temperature diagrams. This work was undertaken with the objective to analyse commercial nickel-titanium alloys for orthodontics application, using the dynamical mechanical analyser - DMA. Four NiTi 0,017 X 0,025'' archwires were studied. The archwires were Copper NiTi 35 deg C (Ormco), Neo Sentalloy F200 (GAC), Nitinol Superelastic (Unitek) and NiTi (GAC). The different mechanodynamical properties such as elasticity and damping moduli were evaluated. Each commercial material was evaluated with and without a 1 N static force, aiming to evaluate phase transition temperature variation with stress. The austenitic to martensitic phase ratio, for the experiments without static force, was in the range of 1.59 to 1.85. For the 1 N static force tests the austenitic to martensitic phase ratio, ranged from 1.28 to 1.57 due to the higher martensite elasticity modulus. With elastic modulus variation with temperature behaviour, the orthodontist has the knowledge of the force variation applied in the tooth in relation to the oral cavity temperature change, for nickel-titanium alloys that undergo phase transformation. The damping capacity of the studied alloys depends on the materials state: martensitic phase; austenitic phase or during phase transformation. The martensitic phase shows higher dumping capacity. During phase transformation, an internal friction peak may be observed for the CuNiTi 35 deg C and Neo

Mechanodynamical analysis of nickel-titanium alloys for orthodontics application; Analise mecanodinamica de ligas de niquel-titanio para aplicacao ortodontica

Energy Technology Data Exchange (ETDEWEB)

Arruda, Carlos do Canto

2002-07-01

Nickel-titanium alloys may coexist in more than one crystalline structure. There is a high temperature phase, austenite, and a low temperature phase, martensite. The metallurgical basis for the superelasticity and the shape memory effect relies in the ability of these alloys to transform easily from one phase to another. There are three essential factors for the orthodontist to understand nickel-titanium alloys behaviour: stress; deflection; and temperature. These three factors are related to each other by the stress-deflection, stress-temperature and deflection-temperature diagrams. This work was undertaken with the objective to analyse commercial nickel-titanium alloys for orthodontics application, using the dynamical mechanical analyser - DMA. Four NiTi 0,017 X 0,025'' archwires were studied. The archwires were Copper NiTi 35 deg C (Ormco), Neo Sentalloy F200 (GAC), Nitinol Superelastic (Unitek) and NiTi (GAC). The different mechanodynamical properties such as elasticity and damping moduli were evaluated. Each commercial material was evaluated with and without a 1 N static force, aiming to evaluate phase transition temperature variation with stress. The austenitic to martensitic phase ratio, for the experiments without static force, was in the range of 1.59 to 1.85. For the 1 N static force tests the austenitic to martensitic phase ratio, ranged from 1.28 to 1.57 due to the higher martensite elasticity modulus. With elastic modulus variation with temperature behaviour, the orthodontist has the knowledge of the force variation applied in the tooth in relation to the oral cavity temperature change, for nickel-titanium alloys that undergo phase transformation. The damping capacity of the studied alloys depends on the materials state: martensitic phase; austenitic phase or during phase transformation. The martensitic phase shows higher dumping capacity. During phase transformation, an internal friction peak may be observed for the CuNiTi 35 deg C and Neo Sentalloy F

Metallurgical characterization of controlled memory wire nickel-titanium rotary instruments.

Science.gov (United States)

Shen, Ya; Zhou, Hui-Min; Zheng, Yu-Feng; Campbell, Les; Peng, Bin; Haapasalo, Markus

2011-11-01

To improve the fracture resistance of nickel-titanium (NiTi) files, manufacturers have introduced new alloys and developed new manufacturing processes for the fabrication of NiTi files. This study aimed to examine the phase transformation behavior and microstructure of NiTi instruments from a novel controlled memory NiTi wire (CM wire). Instruments of EndoSequence (ES), ProFile (PF), ProFile Vortex (Vortex), Twisted Files (TF), Typhoon (TYP), and Typhoon™ CM (TYP CM), all size 25/.04, were examined by differential scanning calorimetry (DSC) and x-ray diffraction (XRD). Microstructures of etched instruments were observed by optical microscopy and scanning electron microscopy with x-ray energy-dispersive spectrometric (EDS) analyses. The DSC analyses showed that each segment of the TYP CM and Vortex instruments had an austenite transformation completion or austenite-finish (A(f)) temperature exceeding 37°C, whereas the NiTi instruments made from conventional superelastic NiTi wire (ES, PF, and TYP) and TF had A(f) temperatures substantially below mouth temperature. The higher A(f) temperature of TYP CM instruments was consistent with a mixture of austenite and martensite structure, which was observed at room temperature with XRD. All NiTi instruments had room temperature martensite microstructures consisting of colonies of lenticular features with substantial twinning. EDS analysis indicated that the precipitates in all NiTi instruments were titanium-rich, with an approximate composition of Ti(2)Ni. The TYP CM and Vortex instruments with heat treatment contribute to increase austenite transformation temperature. The CM instrument has significant changes in the phase transformation behavior, compared with conventional superelastic NiTi instruments. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Comparison of galvanic corrosion potential of metal injection molded brackets to that of conventional metal brackets with nickel-titanium and copper nickel-titanium archwire combinations.

Science.gov (United States)

Varma, D Praveen Kumar; Chidambaram, S; Reddy, K Baburam; Vijay, M; Ravindranath, D; Prasad, M Rajendra

2013-05-01

The aim of the study is to investigate the galvanic corrosion potential of metal injection molding (MIM) brackets to that of conventional brackets under similar in vitro conditions with nickel-titanium and copper nickel-titanium archwires. Twenty-five maxillary premolar MIM stainless steel brackets and 25 conventional stainless steel brackets and archwires, 0.16 inch, each 10 mm length, 25 nickeltitanium wires, 25 copper nickel-titanium wires were used. They were divided into four groups which had five samples each. Combination of MIM bracket with copper nickel-titanium wire, MIM bracket with nickel-titanium wire and conventional stainless steel brackets with copper nickel-titanium wire and conventional stainless steel brackets with nickel-titanium wires which later were suspended in 350 ml of 1 M lactic acid solution media. Galvanic corrosion potential of four groups were analyzed under similar in vitro conditions. Precorrosion and postcorrosion elemental composition of MIM and conventional stainless steel bracket by scanning electron microscope (SEM) with energy dispersive spectroscope (EDS) was done. MIM bracket showed decreased corrosion susceptibility than conventional bracket with copper nickeltitanium wire. Both MIM and conventional bracket showed similar corrosion resistance potential in association with nickel-titanium archwires. It seems that both brackets are more compatible with copper nickel-titanium archwires regarding the decrease in the consequences of galvanic reaction. The EDS analysis showed that the MIM brackets with copper nickel-titanium wires released less metal ions than conventional bracket with copper nickeltitanium wires. MIM brackets showed decreased corrosion susceptibility, copper nickel-titanium archwires are compatible with both the brackets than nickel-titanium archwires. Clinically MIM and conventional brackets behaved more or less similarly in terms of corrosion resistance. In order to decrease the corrosion potential of MIM

Vibration Sensor Monitoring of Nickel-Titanium Alloy Turning for Machinability Evaluation

Directory of Open Access Journals (Sweden)

Tiziana Segreto

2017-12-01

Full Text Available Nickel-Titanium (Ni-Ti alloys are very difficult-to-machine materials causing notable manufacturing problems due to their unique mechanical properties, including superelasticity, high ductility, and severe strain-hardening. In this framework, the aim of this paper is to assess the machinability of Ni-Ti alloys with reference to turning processes in order to realize a reliable and robust in-process identification of machinability conditions. An on-line sensor monitoring procedure based on the acquisition of vibration signals was implemented during the experimental turning tests. The detected vibration sensorial data were processed through an advanced signal processing method in time-frequency domain based on wavelet packet transform (WPT. The extracted sensorial features were used to construct WPT pattern feature vectors to send as input to suitably configured neural networks (NNs for cognitive pattern recognition in order to evaluate the correlation between input sensorial information and output machinability conditions.

Vibration Sensor Monitoring of Nickel-Titanium Alloy Turning for Machinability Evaluation.

Science.gov (United States)

Segreto, Tiziana; Caggiano, Alessandra; Karam, Sara; Teti, Roberto

2017-12-12

Nickel-Titanium (Ni-Ti) alloys are very difficult-to-machine materials causing notable manufacturing problems due to their unique mechanical properties, including superelasticity, high ductility, and severe strain-hardening. In this framework, the aim of this paper is to assess the machinability of Ni-Ti alloys with reference to turning processes in order to realize a reliable and robust in-process identification of machinability conditions. An on-line sensor monitoring procedure based on the acquisition of vibration signals was implemented during the experimental turning tests. The detected vibration sensorial data were processed through an advanced signal processing method in time-frequency domain based on wavelet packet transform (WPT). The extracted sensorial features were used to construct WPT pattern feature vectors to send as input to suitably configured neural networks (NNs) for cognitive pattern recognition in order to evaluate the correlation between input sensorial information and output machinability conditions.

Comparative in vitro biocompatibility of nickel-titanium, pure nickel, pure titanium, and stainless steel: genotoxicity and atomic absorption evaluation.

Science.gov (United States)

Assad, M; Lemieux, N; Rivard, C H; Yahia, L H

1999-01-01

The genotoxicity level of nickel-titanium (NiTi) was compared to that of its pure constituents, pure nickel (Ni) and pure titanium (Ti) powders, and also to 316L stainless steel (316L SS) as clinical reference material. In order to do so, a dynamic in vitro semiphysiological extraction was performed with all metals using agitation and ISO requirements. Peripheral blood lymphocytes were then cultured in the presence of all material extracts, and their comparative genotoxicity levels were assessed using electron microscopy-in situ end-labeling (EM-ISEL) coupled to immunogold staining. Cellular chromatin exposition to pure Ni and 316L SS demonstrated a significantly stronger gold binding than exposition to NiTi, pure Ti, or the untreated control. In parallel, graphite furnace atomic absorption spectrophotometry (AAS) was also performed on all extraction media. The release of Ni atoms took the following decreasing distribution for the different resulting semiphysiological solutions: pure Ni, 316L SS, NiTi, Ti, and controls. Ti elements were detected after elution of pure titanium only. Both pure titanium and nickel-titanium specimens obtained a relative in vitro biocompatibility. Therefore, this quantitative in vitro study provides optimistic results for the eventual use of nickel-titanium alloys as surgical implant materials.

Nickel and titanium nanoboride composite coating

International Nuclear Information System (INIS)

Efimova, K A; Galevsky, G V; Rudneva, V V; Kozyrev, N A; Orshanskaya, E G

2015-01-01

Electrodeposition conditions, structural-physical and mechanical properties (microhardness, cohesion with a base, wear resistance, corrosion currents) of electroplated composite coatings on the base of nickel with nano and micro-powders of titanium boride are investigated. It has been found out that electro-crystallization of nickel with boride nanoparticles is the cause of coating formation with structural fragments of small sizes, low porosity and improved physical and mechanical properties. Titanium nano-boride is a component of composite coating, as well as an effective modifier of nickel matrix. Nano-boride of the electrolyte improves efficiency of the latter due to increased permissible upper limit of the cathodic current density. (paper)

Effect of saliva on load-deflection characteristics of superelastic nickel-titanium orthodontic wires.

Science.gov (United States)

Hosseinzadeh Nik, T; Ghadirian, H; Ahmadabadi, M Nili; Shahhoseini, T; Haj-Fathalian, M

2012-01-01

Most published results about the characteristics of NiTi wires are based on the mechanical laboratory tests on the as-received wires.The purpose of this study was to investigate the effect of saliva on load-deflection characteristics of superelastic NiTi wires. In this experimental study, 15 wires of three kinds of superelastic NiTi wires (Sentalloy, Force I and Truflex) were prepared. Five specimens of each wire were tested in the as-received condition (T0) to provide baseline information and the remaining wires were divided into two groups of five. Half of them were kept inside artificial saliva for one month (T1), while the others were kept in air (T2). After 30 days, three-point bending test was done in a dental arch model and data from selected points on the unloading phase of the generated graphs were used for statistical analysis. Force I and Truflex showed significantly greater force than Sentalloy. The load values of Truflex and Force I after one month exposed to artificial saliva (T1) decreased significantly, but Sentalloy was not affected significantly. The plateau gap values were not considerably different among T0, T1 and T2. Saliva decreased the load of Force I and Truflex significantly, but it did not have a statistically significant effect on Sentalloy.

Nickel contaminated titanium weld wire study

International Nuclear Information System (INIS)

Coffin, G.R.; Sumstine, R.L.

1979-01-01

Attachment of thermocouples to fuel rod welding problems at Exxon Nuclear Company and INEL prompted an investigation study of the titanium filler wire material. It was found that the titanium filler wire was contaminated with nickel which was jacketed on the wire prior to the drawing process at the manufacturers. A method was developed to 100% inspect all filler wire for future welding application. This method not only indicates the presence of nickel contamination but indicates quantity of contamination. The process is capable of high speed inspection necessary for various high speed manufacturing processes

Surface characterization of nickel titanium orthodontic arch wires

Science.gov (United States)

Krishnan, Manu; Seema, Saraswathy; Tiwari, Brijesh; Sharma, Himanshu S.; Londhe, Sanjay; Arora, Vimal

2015-01-01

Background Surface roughness of nickel titanium orthodontic arch wires poses several clinical challenges. Surface modification with aesthetic/metallic/non metallic materials is therefore a recent innovation, with clinical efficacy yet to be comprehensively evaluated. Methods One conventional and five types of surface modified nickel titanium arch wires were surface characterized with scanning electron microscopy, energy dispersive analysis, Raman spectroscopy, Atomic force microscopy and 3D profilometry. Root mean square roughness values were analyzed by one way analysis of variance and post hoc Duncan's multiple range tests. Results Study groups demonstrated considerable reduction in roughness values from conventional in a material specific pattern: Group I; conventional (578.56 nm) > Group V; Teflon (365.33 nm) > Group III; nitride (301.51 nm) > Group VI (i); rhodium (290.64 nm) > Group VI (ii); silver (252.22 nm) > Group IV; titanium (229.51 nm) > Group II; resin (158.60 nm). It also showed the defects with aesthetic (resin/Teflon) and nitride surfaces and smooth topography achieved with metals; titanium/silver/rhodium. Conclusions Resin, Teflon, titanium, silver, rhodium and nitrides were effective in decreasing surface roughness of nickel titanium arch wires albeit; certain flaws. Findings have clinical implications, considering their potential in lessening biofilm adhesion, reducing friction, improving corrosion resistance and preventing nickel leach and allergic reactions. PMID:26843749

Effect of Saliva on Load-Deflection Characteristics of Superelastic Nickel-Titanium Orthodontic Wires

OpenAIRE

Hosseinzadeh Nik, T.; Ghadirian, H.; Ahmadabadi, M. Nili; Shahhoseini, T.; Haj-Fathalian, M.

2012-01-01

Statement of Problem: Most published results about the features of NiTi wires are based on the mechanical laboratory tests in a dry environment.Purpose of Study: The purpose of this study was to investigate the effect of saliva on load-deflection characteristics of superelastic NiTi wires.Materials and Methods: In this experimental study, 15 wires of three kinds of NiTi wires (Sentalloy, Force I and Truflex) were prepared; five of them were tested in their as-received condition to provide bas...

Using endografts from superelastic titanium-nickelid-based alloy singular tissue plural tissues in organ-preserving surgery of laryngeal cancer

Energy Technology Data Exchange (ETDEWEB)

Kulbakin, D. E., E-mail: kulbakin-d@mail.ru [Tomsk Cancer Research Institute, 5 Kooperativny Street, Tomsk, 634050 (Russian Federation); Tomsk State University, 36, Lenin Avenue, Tomsk, 634050 (Russian Federation); Mukhamedov, M. R., E-mail: muhamedov@oncology.tomsk.ru [Tomsk Cancer Research Institute, 5 Kooperativny Street, Tomsk, 634050 (Russian Federation); Siberian State Medical University, 2, Moscow Highway, Tomsk, 634050 (Russian Federation); Choynzonov, E. L., E-mail: choynzonov@gmail.com [Tomsk Cancer Research Institute, 5 Kooperativny Street, Tomsk, 634050 (Russian Federation); Siberian State Medical University, 2, Moscow Highway, Tomsk, 634050 (Russian Federation); National Research Tomsk Polytechnic University, 30, Lenin Avenue, Tomsk, 634050 (Russian Federation); Gynter, V. E., E-mail: tc77@rec.tsu.ru [Tomsk State University, 36, Lenin Avenue, Tomsk, 634050 (Russian Federation); Research Institute of Medical Materials, 17, 19 Gv. Divizii, Tomsk, 634034 (Russian Federation)

2015-11-17

Our study has demonstrated feasibility of performing larynx preservation surgeries in patients with recurrent laryngeal cancer after failure of radiotherapy. The technique of combined laryngeal reconstruction with endografts from superelastic titanium-nickelid-based alloy Singular tissue Plural tissues results in improvement of life quality by preserving laryngeal functions.

Metallurgical characterization of M-Wire nickel-titanium shape memory alloy used for endodontic rotary instruments during low-cycle fatigue.

Science.gov (United States)

Ye, Jia; Gao, Yong

2012-01-01

Rotary instruments made of a new nickel-titanium (NiTi) alloy (M-Wire) have shown improved cyclic fatigue resistance and mechanical properties compared with those made of conventional superelastic NiTi wires. The objective of this study was to characterize microstructural changes of M-Wire throughout the cyclic fatigue process under controlled strain amplitude. The average fatigue life was calculated from 30 M-Wire samples that were subjected to a strain-controlled (≈ 4%) rotating bend fatigue test at room temperature and rotational speed of 300 rpm. Microstructural evolution of M-Wire has been investigated by different metallurgical characterization techniques, including differential scanning calorimetry, Vickers microhardness, and transmission electron microscopy at 4 different stages (as-received state, 30%, 60%, and 90% of average fatigue life). During rotating bend fatigue test, no statistically significant difference (P > .05) was found on austenite finish temperatures between as-received M-Wire and fatigued samples. However, significant differences (P Wire are expected to have higher strength and wear resistance than similar instruments made of conventional superelastic NiTi wires because of its unique nano-crystalline martensitic microstructure. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Evaluation of cyclic flexural fatigue of M-wire nickel-titanium rotary instruments.

Science.gov (United States)

Al-Hadlaq, Solaiman M S; Aljarbou, Fahad A; AlThumairy, Riyadh I

2010-02-01

This study was conducted to investigate cyclic flexural fatigue resistance of GT series X rotary files made from the newly developed M-wire nickel-titanium alloy compared with GT and Profile nickel-titanium files made from a conventional nickel-titanium alloy. Fifteen files, size 30/0.04, of each type were used to evaluate the cyclic flexural fatigue resistance. A simple device was specifically constructed to measure the time each file type required to fail under cyclic flexural fatigue testing. The results of this experiment indicated that the GT series X files had superior cyclic flexural fatigue resistance than the other 2 file types made from a conventional nickel-titanium alloy (P = .004). On the other hand, the difference between the Profile and the GT files was not statistically significant. The findings of this study suggest that size 30/0.04 nickel-titanium rotary files made from the newly developed M-wire alloy have better cyclic flexural fatigue resistance than files of similar design and size made from the conventional nickel-titanium alloy. Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

The effect of ligation on the load deflection characteristics of nickel titanium orthodontic wire.

Science.gov (United States)

Kasuya, Shugo; Nagasaka, Satoshi; Hanyuda, Ai; Ishimura, Sadao; Hirashita, Ayao

2007-12-01

This study examined the effect of ligation on the load-deflection characteristics of nickel-titanium (NiTi) orthodontic wire. A modified three-point bending system was used for bending the NiTi round wire, which was inserted and ligated in the slots of three brackets, one of which was bonded to each of the three bender rods. Three different ligation methods, stainless steel ligature (SSL), slot lid (SL), and elastomeric ligature (EL), were employed, as well as a control with neither bracket nor ligation (NBL). The tests were repeated five times under each condition. Comparisons were made of load-deflection curve, load at maximum deflection of 2,000 microm, and load at a deflection of 1,500 microm during unloading. Analysis of Variance (ANOVA) and Dunnett's test were conducted to determine method difference (alpha = 0.05). The interaction between deflection and ligation was tested, using repeated-measures ANOVA (alpha = 0.05). The load values of the ligation groups were two to three times greater than the NBL group at a deflection of 1,500 microm during unloading: 4.37 N for EL, 3.90 N for SSL, 3.02 N for SL, and 1.49 N for NBL (P wire may make NiTi wire exhibit a significantly heavier load than that traditionally expected. NiTi wire exhibited the majority of its true superelasticity with SL, whereas EL may act as a restraint on its superelasticity.

Superelastic load cycling of Gum Metal

International Nuclear Information System (INIS)

Vorontsov, V.A.; Jones, N.G.; Rahman, K.M.; Dye, D.

2015-01-01

The superelastic beta titanium alloy, Gum Metal, has been found to accumulate plastic strain during tensile load cycling in the superelastic regime. This is evident from the positive drift of the macroscopic stress vs. strain hysteresis curve parallel to the strain axis and the change in its geometry subsequent to every load–unload cycle. In addition, there is a progressive reduction in the hysteresis loop width and in the stress at which the superelastic transition occurs. In situ synchrotron X-ray diffraction has shown that the lattice strain exhibited the same behaviour as that observed in macroscopic measurements and identified further evidence of plastic strain accumulation. The mechanisms responsible for the observed behaviour have been evaluated using transmission electron microscopy, which revealed a range of different defects that formed during load cycling. The formation of these defects is consistent with the classical mathematical theory for the bcc to orthorhombic martensitic transformation. It is the accumulation of these defects over time that alters its superelastic behaviour

Mechanical and microstructural integrity of nickel-titanium and stainless steel laser joined wires

International Nuclear Information System (INIS)

Vannod, J.; Bornert, M.; Bidaux, J.-E.; Bataillard, L.; Karimi, A.; Drezet, J.-M.; Rappaz, M.; Hessler-Wyser, A.

2011-01-01

The biomedical industry shows increasing interest in the joining of dissimilar metals, especially with the aim of developing devices that combine different mechanical and corrosive properties. As an example, nickel-titanium shape memory alloys joined to stainless steel are very promising for new invasive surgery devices, such as guidewires. A fracture mechanics study of such joined wires was carried out using in situ tensile testing and scanning electron microscopy imaging combined with chemical analysis, and revealed an unusual fracture behaviour at superelastic stress. Nanoindentation was performed to determine the mechanical properties of the welded area, which were used as an input for mechanical computation in order to understand this unexpected behaviour. Automated image correlation allowed verification of the mechanical modelling and a reduced stress-strain model is proposed to explain the special fracture mechanism. This study reveals the fact that tremendous property changes at the interface between the NiTi base wire and the weld area have more impact on the ultimate tensile strength than the chemical composition variation across the welded area.

An evaluation of the transition temperature range of super-elastic orthodontic NiTi springs using differential scanning calorimetry.

Science.gov (United States)

Barwart, O; Rollinger, J M; Burger, A

1999-10-01

Differential scanning calorimetry (DSC) was used to determine the transition temperature ranges (TTR) of four types of super-elastic orthodontic nickel-titanium coil springs (Sentalloy). A knowledge of the TTR provides information on the temperature at which a NiTi wire or spring can assume superelastic properties and when this quality disappears. The spring types in this study can be distinguished from each other by their characteristic TTR during cooling and heating. For each tested spring type a characteristic TTR during heating (austenite transformation) and cooling (martensite transformation) was evaluated. The hysteresis of the transition temperature, found between cooling and heating, was 3.4-5.2 K. Depending on the spring type the austenite transformation started (As) at 9.7-17.1 degrees C and finished (Af) at 29.2-37 degrees C. The martensite transformation starting temperature (Ms) was evaluated at 32.6-25.4 degrees C, while Mf (martensite transformation finishing temperature) was 12.7-6.5 degrees C. The results show that the springs become super-elastic when the temperature increases and As is reached. They undergo a loss of super-elastic properties and a rapid decrease in force delivery when they are cooled to Mf. For the tested springs, Mf and As were found to be below room temperature. Thus, at room temperature and some degrees lower, all the tested springs exert super-elastic properties. For orthodontic treatment this means the maintenance of super-elastic behaviour, even when mouth temperature decreases to about room temperature as can occur, for example, during meals.

Nickel-Titanium Wire as Suture Material: A New Technique for the Fixation of Skin.

Science.gov (United States)

Li, Haidong; Song, Tao

2018-01-29

To introduce nickel-titanium wire as suture material for closure of incisions in cleft lip procedures. Closure of skin incisions using nickel-titanium wire as suture material, with postoperative follow-up wound evaluation. There was excellent patient satisfaction and good cosmetic outcome. Nickel-titanium wire is an excellent alternative for suture closure of cleft lip surgical incisions.

Copper and nickel alloys and titanium for seawater applications

International Nuclear Information System (INIS)

Richter, H.

1977-01-01

Copper and nickel alloys and titanium have been successfully used for heat exchangers on ships, in power plants and for chemical apparatus and piping systems because of their resistance against corrosion in sea water. Aluminium brass and copper nickel alloys, the standard materials for condensers and coolers, however, may be attacked, the corrosion depending on water quality, water velocity, and structural conditions. The mechanisms of corrosion are discussed. Under severe conditions the use of titanium may be indicated. The use of nickel base alloys is advantageous at elevated temperatures, e.g. for chemical reactions and for evaporation processes. Examples are given for application and for prevention of corrosion. (orig.) [de

Torsion and bending properties of shape memory and superelastic nickel-titanium rotary instruments.

Science.gov (United States)

Ninan, Elizabeth; Berzins, David W

2013-01-01

Recently introduced into the market are shape memory nickel-titanium (NiTi) rotary files. The objective of this study was to investigate the torsion and bending properties of shape memory files (CM Wire, HyFlex CM, and Phoenix Flex) and compare them with conventional (ProFile ISO and K3) and M-Wire (GT Series X and ProFile Vortex) NiTi files. Sizes 20, 30, and 40 (n = 12/size/taper) of 0.02 taper CM Wire, Phoenix Flex, K3, and ProFile ISO and 0.04 taper HyFlex CM, ProFile ISO, GT Series X, and Vortex were tested in torsion and bending per ISO 3630-1 guidelines by using a torsiometer. All data were statistically analyzed by analysis of variance and the Tukey-Kramer test (P = .05) to determine any significant differences between the files. Significant interactions were present among factors of size and file. Variability in maximum torque values was noted among the shape memory files brands, sometimes exhibiting the greatest or least torque depending on brand, size, and taper. In general, the shape memory files showed a high angle of rotation before fracture but were not statistically different from some of the other files. However, the shape memory files were more flexible, as evidenced by significantly lower bending moments (P < .008). Shape memory files show greater flexibility compared with several other NiTi rotary file brands. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

[Application of compression equipment using the "form memory" effect and super-elasticity of titanium nickelide in surgery for rectal cancer].

Science.gov (United States)

Vlasov, A A; Vazhenin, A V; Plotnikov, V V; Spirev, V V; Chinarev, Iu B

2010-01-01

The study is concerned with development of equipment for forming circular compression intestinal anastomosis using the "form memory" effect and super-elasticity of titanium nickelide. A sequence of technological operations is suggested, experimental tests and clinical trials carried out and immediate and end-results for anterior resection in rectal cancer are evaluated. Compression equipment for forming colorectal anastomosis proved reliable in long-term operation.

Copper, Aluminum and Nickel: A New Monocrystalline Orthodontic Alloy

Science.gov (United States)

Wierenga, Mark

Introduction: This study was designed to evaluate, via tensile and bend testing, the mechanical properties of a newly-developed monocrystalline orthodontic archwire comprised of a blend of copper, aluminum, and nickel (CuAlNi). Methods: The sample was comprised of three shape memory alloys; CuAlNi, copper nickel titanium (CuNiTi), and nickel titanium (NiTi); from various orthodontic manufacturers in both 0.018" round and 0.019" x 0.025" rectangular dimensions. Additional data was gathered for similarly sized stainless steel and beta-titanium archwires as a point of reference for drawing conclusions about the relative properties of the archwires. Measurements of loading and unloading forces were recorded in both tension and deflection testing. Repeated-measure ANOVA (alpha= 0.05) was used to compare loading and unloading forces across wires and one-way ANOVA (alpha= 0.05) was used to compare elastic moduli and hysteresis. To identify significant differences, Tukey post-hoc comparisons were performed. Results: The modulus of elasticity, deflection forces, and hysteresis profiles of CuAlNi were significantly different than the other superelastic wires tested. In all tests, CuAlNi had a statistically significant lower modulus of elasticity compared to the CuNiTi and NiTi wires (P orthodontic metallurgy.

The release of nickel from orthodontic NiTi wires is increased by dynamic mechanical loading but not constrained by surface nitridation.

Science.gov (United States)

Peitsch, T; Klocke, A; Kahl-Nieke, B; Prymak, O; Epple, M

2007-09-01

The influence of dynamic mechanical loading and of surface nitridation on the nickel release from superelastic nickel-titanium orthodontic wires was investigated under ultrapure conditions. Commercially available superelastic NiTi arch wires (size 0.018 x 0.025'') without surface modification (Neo Sentalloy) and with nitrogen ion implantation surface treatment (Neo Sentalloy Ionguard) were analyzed. Mechanical loading of wire segments with a force similar to the physiological situation was performed with a frequency of 5 Hz in ultrapure water and saline solution, respectively. The release of nickel was monitored by atomic absorption spectroscopy for up to 36 days. The mechanically loaded wires released significantly more nickel ( approximately 45 ng cm(-2) d(-1)) than did nonloaded wires (<1 ng cm(-2) d(-1)). There was no statistically significant effect of the testing solution (water or NaCl) or of the surface nitridation. The total amount of released nickel was small in all cases, but may nevertheless account for the occasional clinical observations of adverse reactions during application of NiTi-based orthodontic appliances. The surface nitridation did not constrain the release of nickel from NiTi under continuous mechanical stress.

Mechanical and microstructural characterization of new nickel-free low modulus β-type titanium wires during thermomechanical treatments

Energy Technology Data Exchange (ETDEWEB)

Guillem-Martí, J. [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Campus Río Ebro, Edificio I+D Bloque 5, 1a planta, C/ Poeta Mariano Esquillor s/n, 50018 Zaragoza (Spain); Centre for Research in NanoEngineering (CRNE) – UPC, C/Pascual i Vila 15, 08028 Barcelona (Spain); Herranz-Díez, C. [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Campus Río Ebro, Edificio I+D Bloque 5, 1a planta, C/ Poeta Mariano Esquillor s/n, 50018 Zaragoza (Spain); Shaffer, J.E. [Fort Wayne Metals Research Products Corporation, 9609 Ardmore Avenue, 46809 Fort Wayne (United States); Gil, F.J. [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Campus Río Ebro, Edificio I+D Bloque 5, 1a planta, C/ Poeta Mariano Esquillor s/n, 50018 Zaragoza (Spain); Centre for Research in NanoEngineering (CRNE) – UPC, C/Pascual i Vila 15, 08028 Barcelona (Spain); and others

2015-06-11

NiTi alloy is the only practical shape memory alloy (SMA) in biomedical use because of its excellent mechanical stability and functionality. However, it is estimated that between 4.5% and 28.5% of the population are hypersensitive to nickel metal, with a higher prevalence in females. Therefore, developing nickel-free low modulus β-type titanium alloys showing shape memory or super elastic behavior would have a great interest in the biomaterials field. Homogeneous 127 μm diameter Ti25Hf21Nb wires were produced and compared to straight annealed Ti–50.8 at% Ni (Nitinol) and 90% cold-drawn 316L wires. Microstructural changes taking place during the heat treatment of cold-worked Ti25Hf21Nb wires were investigated. Large plastic deformation during wire drawing and subsequent annealing led to nano-crystallization and amorphization which may contribute to the observed superelasticity. Mechanical properties were characterized using cyclic uniaxial tension and rotary beam fatigue test modes. A modulus of elasticity of less than 60 GPa and axial recoverable strain of greater than 3% were observed with stress hysteresis resembling a reversible stress-induced martensitic transformation at higher temperatures. The new Ti25Hf21Nb alloy is an important candidate for developing Ni-free SMAs in the future.

Mechanical and microstructural characterization of new nickel-free low modulus β-type titanium wires during thermomechanical treatments

International Nuclear Information System (INIS)

Guillem-Martí, J.; Herranz-Díez, C.; Shaffer, J.E.; Gil, F.J.

2015-01-01

NiTi alloy is the only practical shape memory alloy (SMA) in biomedical use because of its excellent mechanical stability and functionality. However, it is estimated that between 4.5% and 28.5% of the population are hypersensitive to nickel metal, with a higher prevalence in females. Therefore, developing nickel-free low modulus β-type titanium alloys showing shape memory or super elastic behavior would have a great interest in the biomaterials field. Homogeneous 127 μm diameter Ti25Hf21Nb wires were produced and compared to straight annealed Ti–50.8 at% Ni (Nitinol) and 90% cold-drawn 316L wires. Microstructural changes taking place during the heat treatment of cold-worked Ti25Hf21Nb wires were investigated. Large plastic deformation during wire drawing and subsequent annealing led to nano-crystallization and amorphization which may contribute to the observed superelasticity. Mechanical properties were characterized using cyclic uniaxial tension and rotary beam fatigue test modes. A modulus of elasticity of less than 60 GPa and axial recoverable strain of greater than 3% were observed with stress hysteresis resembling a reversible stress-induced martensitic transformation at higher temperatures. The new Ti25Hf21Nb alloy is an important candidate for developing Ni-free SMAs in the future

Nasomaxillary hypoplasia with a congenitally missing tooth treated with LeFort II osteotomy, autotransplantation, and nickel-titanium alloy wire.

Science.gov (United States)

Ishida, Takayoshi; Ikemoto, Shigehiro; Ono, Takashi

2015-09-01

In some skeletal Class III adult patients with nasomaxillary hypoplasia, the LeFort I osteotomy provides insufficient correction. This case report describes a 20-year-old woman with a combination of nasomaxillary hypoplasia and a protrusive mandible with a congenitally missing mandibular second premolar. We performed a LeFort II osteotomy for maxillary advancement. Autotransplantation of a tooth was also performed; the donor tooth was used to replace the missing permanent tooth. To increase the chance of success, we applied light continuous force with an improved superelastic nickel-titanium alloy wire technique before extraction and after transplantation. The patient's profile and malocclusion were corrected, and the autotransplanted tooth functioned well. The postero-occlusal relationships were improved, and ideal overbite and overjet relationships were achieved. The methods used in this case represent a remarkable treatment. Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Investigations on laser induced nickel and titanium plasmas

International Nuclear Information System (INIS)

Rahman, M.K.U.; Latif, A.; Bhatti, K.A.; Rafique, M.S.; Yousaf, M.K.

2011-01-01

Experiments were performed to find out plasma parameters for Nickel and Titanium metals which were irradiated in air (1 atm) to produce plasma plume using Q switched Nd: YAG pulsed laser of 1.1 MW, 10 m J, 1064 nm and 9-14 ns. Langmuir probe was used as a diagnostic tool. The signals at different probe voltages were recorded on digital storage oscilloscope. The information carried by the signals was utilized to calculate electron density, electron temperature, Debye's length and number of particles in Debye's sphere. The study shows that the calculated values of these parameters for Nickel and Titanium are different except Debye's length. Plasma parameters strongly depend on probe potentials, material used and ambient conditions. (author)

Cyclic Fatigue of Different Nickel-Titanium Rotary Instruments: A Comparative Study

OpenAIRE

Testarelli, L.; Grande, N.M; Plotino, G; Lendini, M; Pongione, G; Paolis, G. De; Rizzo, F; Milana, V; Gambarini, G

2009-01-01

Since the introduction of nickel-titanium alloy to endodontics, there have been many changes in instrument design, but no significant improvements in the raw material properties, or enhancements in the manufacturing process. Recently, a new method to produce nickel-titanium rotary (NTR) instruments has been developed, in an attempt to obtain instruments that are more flexible and resistant to fatigue. NTR instruments produced using the process of twisting (TF, SybronEndo, Orange, CA) were com...

Effect of environment on fatigue failure of controlled memory wire nickel-titanium rotary instruments.

Science.gov (United States)

Shen, Ya; Qian, Wei; Abtin, Houman; Gao, Yuan; Haapasalo, Markus

2012-03-01

This study examined the fatigue behavior of 2 types of nickel-titanium (NiTi) instruments made from a novel controlled memory NiTi wire (CM wire) under various environment conditions. Three conventional superelastic NiTi instruments of ProFile (Dentsply Maillefer, Ballaigues, Switzerland), Typhoon (Clinician's Choice Dental Products, New Milford, CT), and DS-SS0250425NEYY (Clinician's Choice Dental Products) and 2 new CM wire instruments of Typhoon CM and DS-SS0250425NEYY CM were subjected to rotational bending at the curvature of 35° in air, deionized water, 17% EDTA, or deionized water after immersion in 6% sodium hypochlorite for 25 minutes, and the number of revolutions of fracture (N(f)) was recorded. The fracture surface of all fragments was examined by a scanning electron microscope. The crack-initiation sites and the percentage of dimple area to the whole fracture cross-section were noted. Two new CM Wire instruments yielded an improvement of >4 to 9 times in N(f) than conventional NiTi files with the same design under various environments (P Wire instruments was significantly longer in liquid media than in air (P wire had one crack origin. The values of the area fraction occupied by the dimple region were significantly smaller on CM NiTi instruments than in conventional NiTi instruments under various environments (P < .05). Within the limitations of this study, the type of NiTi metal alloy (CM files vs conventional superelastic NiTi files) influences the cyclic fatigue resistance under various environments. The fatigue life of CM instruments is longer in liquid media than in air. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Innovations: laser-cutting nickel-titanium

Energy Technology Data Exchange (ETDEWEB)

Dickson, T.R.; Moore, B.; Toyama, N. [LPL Systems, Inc., Mountain View, CA (United States)

2002-07-01

Laser-cutting is well established as the preferred method for manufacturing many endovascular medical devices. Sometimes laser processing has been poorly understood by nickel-titanium (NiTi) material suppliers, medical device manufacturers, and device designers, but the field has made important strides in the past several years. A variety of sample, nonspecific applications are presented for cutting tubing and sheet stock. Limiting constraints, key considerations, and areas for future development are identified. (orig.)

Fatigue Assessment of Nickel-Titanium Peripheral Stents: Comparison of Multi-Axial Fatigue Models

Science.gov (United States)

Allegretti, Dario; Berti, Francesca; Migliavacca, Francesco; Pennati, Giancarlo; Petrini, Lorenza

2018-02-01

Peripheral Nickel-Titanium (NiTi) stents exploit super-elasticity to treat femoropopliteal artery atherosclerosis. The stent is subject to cyclic loads, which may lead to fatigue fracture and treatment failure. The complexity of the loading conditions and device geometry, coupled with the nonlinear material behavior, may induce multi-axial and non-proportional deformation. Finite element analysis can assess the fatigue risk, by comparing the device state of stress with the material fatigue limit. The most suitable fatigue model is not fully understood for NiTi devices, due to its complex thermo-mechanical behavior. This paper assesses the fatigue behavior of NiTi stents through computational models and experimental validation. Four different strain-based models are considered: the von Mises criterion and three critical plane models (Fatemi-Socie, Brown-Miller, and Smith-Watson-Topper models). Two stents, made of the same material with different cell geometries are manufactured, and their fatigue behavior is experimentally characterized. The comparison between experimental and numerical results highlights an overestimation of the failure risk by the von Mises criterion. On the contrary, the selected critical plane models, even if based on different damage mechanisms, give a better fatigue life estimation. Further investigations on crack propagation mechanisms of NiTi stents are required to properly select the most reliable fatigue model.

Fatigue Assessment of Nickel-Titanium Peripheral Stents: Comparison of Multi-Axial Fatigue Models

Science.gov (United States)

Allegretti, Dario; Berti, Francesca; Migliavacca, Francesco; Pennati, Giancarlo; Petrini, Lorenza

2018-03-01

Peripheral Nickel-Titanium (NiTi) stents exploit super-elasticity to treat femoropopliteal artery atherosclerosis. The stent is subject to cyclic loads, which may lead to fatigue fracture and treatment failure. The complexity of the loading conditions and device geometry, coupled with the nonlinear material behavior, may induce multi-axial and non-proportional deformation. Finite element analysis can assess the fatigue risk, by comparing the device state of stress with the material fatigue limit. The most suitable fatigue model is not fully understood for NiTi devices, due to its complex thermo-mechanical behavior. This paper assesses the fatigue behavior of NiTi stents through computational models and experimental validation. Four different strain-based models are considered: the von Mises criterion and three critical plane models (Fatemi-Socie, Brown-Miller, and Smith-Watson-Topper models). Two stents, made of the same material with different cell geometries are manufactured, and their fatigue behavior is experimentally characterized. The comparison between experimental and numerical results highlights an overestimation of the failure risk by the von Mises criterion. On the contrary, the selected critical plane models, even if based on different damage mechanisms, give a better fatigue life estimation. Further investigations on crack propagation mechanisms of NiTi stents are required to properly select the most reliable fatigue model.

On aging of iron-nickel-titanium alloys

International Nuclear Information System (INIS)

Vintajkin, E.Z.; Dmitriev, V.B.; Udovenko, V.A.

1978-01-01

The mechanism of structural transformations on the initial stages of aging of Fe-(26-29) at. % Ni-(2.5-5.75) at. % Ti alloys was studied by neutron radiography. It was shown that at the earliest aging stages at 550 deg C there appear ordered areas which are FCC nuclei of the Ni 3 Ti phase. The rate of nucleation depends on the content of titanium in the all. In alloys with more than 3% Ti, nuclei appear even at the hardening stage. During the subsequent aging, the nuclei are enriched with nickel and titanium

[Torque resistance of three different types of nickel-titanium rotary instruments].

Science.gov (United States)

Sun, Wei; Hou, Ben-xiang

2010-10-01

To compare torsional fracture of three different types of nickel-titanium rotary instruments ProTaper, Hero642 and Mtwo by making a stimulate models in vitro. Through the establishment of model in vitro, compared the different time with 3 kinds of nickel titanium file in cutting-edge bound occurs, and to observe the section of fractured instruments by scanning electron microscope. The resistence to torque was different from three types of nickel titanium instruments. The time to fracture of Mtwo was significantly longer than ProTaper's and Hero642's, but ProTaper's and Hero642's had no significant difference. Three kinds cross-sectional design were different, a lot of toughness nests were seen in broken surface. Most of them were ductile fracture. Time to fracture was influenced by the quality disfigurement. The resistance to torque of Mtwo was better than ProTaper and Hero642. The lifespan was influenced by the design of cross-section. The quality disfigurement of the files reduced the resistance to flexual fatigue.

Welding of titanium and nickel alloy by combination of explosive welding and spark plasma sintering technologies

Energy Technology Data Exchange (ETDEWEB)

Malyutina, Yu. N., E-mail: iuliiamaliutina@gmail.com; Bataev, A. A., E-mail: bataev@adm.nstu.ru; Shevtsova, L. I., E-mail: edeliya2010@mail.ru [Novosibirsk State Technical University, Novosibirsk, 630073 (Russian Federation); Mali, V. I., E-mail: vmali@mail.ru; Anisimov, A. G., E-mail: anis@hydro.nsc.ru [Lavrentyev Institute of Hydrodynamics SB RAS, Novosibirsk, 630090 (Russian Federation)

2015-10-27

A possibility of titanium and nickel-based alloys composite materials formation using combination of explosive welding and spark plasma sintering technologies was demonstrated in the current research. An employment of interlayer consisting of copper and tantalum thin plates makes possible to eliminate a contact between metallurgical incompatible titanium and nickel that are susceptible to intermetallic compounds formation during their interaction. By the following spark plasma sintering process the bonding has been received between titanium and titanium alloy VT20 through the thin powder layer of pure titanium that is distinguished by low defectiveness and fine dispersive structure.

Effect of nickel plating upon tensile tests of uranium--0.75 titanium alloy

International Nuclear Information System (INIS)

Hemperly, V.C.

1975-01-01

Electrolytic-nickel-plated specimens of uranium-0.75 wt percent titanium alloy were tested in air at 20 and 100 percent relative humidities. Tensile-test ductility values were lowered by a high humidity and also by nickel plating alone. Baking the nickel-plated specimens did not eliminate the ductility degradation. Embrittlement because of nickel plating was also evident in tensile tests at -34 0 C. (U.S.)

Comparison of radiographic density and compaction index of root canal obturation using nickel titanium or stainless-steel spreaders

Directory of Open Access Journals (Sweden)

M. Adel

2016-08-01

Full Text Available Background: Both nickel titanium and stainless-steel spreaders are available. The obvious advantage of nickel titanium spreader over stainless steel spreaders is greater penetration in curved canals. Objective: To compare the radiographic density and compaction index of root canal obturation using nickel-titanium or stainless-steel spreaders in curved canals. Methods: In this experimental study the primary weight of 30 acrylic blocks with 45o degrees of apical curvature were measured by a scale (W1. After canals were prepared by step back master apical up to file #30 all blocks were weighed again (W2 and randomly divided in two groups of 15each. All canals were obturated by Cold lateral compaction technique (with nickel-titanium in one group and stainless-steel finger spreaders in another group. After all blocks were reweighed (W3, compaction index (W3-W2/W1-W2 was calculated. One radiograph was taken for each sample. Apical density of the apical third of each canal was measured by digital transmission densitometer. Data were analyzed statistically using T-test. Findings: Mean compaction index for nickel-titanium group was 7.67±2.38 and for stainless-steel group was 9.14±4.06. There was no significant difference between two groups. Mean radiographic density of obturation was 2.05±0.14 in nickel-titanium group and was 2.07±0.21 in stainless-steel group. There was no significant difference between two groups. Conclusion: It is concluded that nickel-titanium spreaders are not superior than stainless-steel spreaders in obturating curved canal.

Pain and discomfort experienced after placement of a conventional or a superelastic NiTi aligning archwire. A randomized clinical trial.

Science.gov (United States)

Fernandes, L M; Ogaard, B; Skoglund, L

1998-01-01

Two nickel-titanium arch-wire types commonly used for initial tooth alignment were compared with regard to the pain/discomfort patients experience during the initial phase of tooth movement. The two arch wires used were a superelastic nickel-titanium alloy, 0.014 inch Sentalloy, Light (GAC International Inc. Central Islip, NY, USA) and a 0.014 inch Nitinol (Unitek, Monrovia, CA, USA), a conventional nickel-titanium aligning archwire. One hundred and twenty-eight consecutive patients attending an orthodontic university clinic and 2 private practices for routine placement of a fixed appliance were randomly assigned one of these 2 initial arch wires. Assessments of pain/discomfort were made daily by means of a 100 mm visual analog scale (VAS) over the first 7-day period after bonding. On the first day, recordings were made every hour for the first 11 hours. The results showed that the level of discomfort increased continuously every hour after the insertion of either a Sentalloy or a Nitinol as first arch wires, with a peak in the first night, remaining high on the second day and decreasing thereafter to baseline level after 7 days. During the first 10 hours it was apparent that the pain/discomfort experienced after placement of a Sentalloy was less than that found with the Nitinol archwire, although a significant difference could be found at 4 hours only. No significant gender-specific differences were found in either archwire group. A significant difference between the upper and lower dental arches was observed during the first 11 hours after placement of either a Sentalloy or a Nitinol arch wire, with the lower arch having the higher pain experience.

Electrochemical and surface characterization of a nickel-titanium alloy

NARCIS (Netherlands)

Wever, Dirk; Veldhuizen, AG; de Vries, J; Busscher, HJ; Uges, DRA; van Horn, James

1998-01-01

For clinical implantation purposes of shape memory metals the nearly equiatomic nickel-titanium (NiTi) alloy is generally used. In this study, the corrosion properties and surface characteristics of this alloy were investigated and compared with two reference controls, AISI 316 LVM stainless steel

Intermetallic Nickel-Titanium Alloys for Oil-Lubricated Bearing Applications

Science.gov (United States)

DellaCorte, C.; Pepper, S. V.; Noebe, R.; Hull, D. R.; Glennon, G.

2009-01-01

An intermetallic nickel-titanium alloy, NITINOL 60 (60NiTi), containing 60 wt% nickel and 40 wt% titanium, is shown to be a promising candidate material for oil-lubricated rolling and sliding contact applications such as bearings and gears. NiTi alloys are well known and normally exploited for their shape memory behavior. When properly processed, however, NITINOL 60 exhibits excellent dimensional stability and useful structural properties. Processed via high temperature, high-pressure powder metallurgy techniques or other means, NITINOL 60 offers a broad combination of physical properties that make it unique among bearing materials. NITINOL 60 is hard, electrically conductive, highly corrosion resistant, less dense than steel, readily machined prior to final heat treatment, nongalling and nonmagnetic. No other bearing alloy, metallic or ceramic encompasses all of these attributes. Further, NITINOL 60 has shown remarkable tribological performance when compared to other aerospace bearing alloys under oil-lubricated conditions. Spiral orbit tribometer (SOT) tests were conducted in vacuum using NITINOL 60 balls loaded between rotating 440C stainless steel disks, lubricated with synthetic hydrocarbon oil. Under conditions considered representative of precision bearings, the performance (life and friction) equaled or exceeded that observed with silicon nitride or titanium carbide coated 440C bearing balls. Based upon this preliminary data, it appears that NITINOL 60, despite its high titanium content, is a promising candidate alloy for advanced mechanical systems requiring superior and intrinsic corrosion resistance, electrical conductivity and nonmagnetic behavior under lubricated contacting conditions.

In vitro force delivery of nickel-titanium superelastic archwires in vertical displacement

Directory of Open Access Journals (Sweden)

Aisha de Souza Gomes Stumpf

2012-12-01

Full Text Available OBJECTIVE: The purpose of this study was to evaluate the force delivered by different superlastic nickel-titanium wires during vertical displacement, in order to determine whether their stress release meets the criteria for constant and light forces that are usually accredited to these archwires. METHOD: Ten samples of 6 brands of 0.016-in archwires (Ormco, GAC, Morelli, TP, American Orthodontics e Rocky Mountain were tested in a complete metal model using Dynalock brackets (3M Unitek™. In the canine position, there was a sliding bracket connected to a pole. This set was related to a load cell of 0.5 kg attached to a universal testing machine (Autograph AG-199kNG, Shimadzu. The crosshead speed was 0.5 mm/min and the maximum displacement was 1.0 mm. The model was submerged in temperature-controlled water. The results were analyzed by ANOVA (p OBJETIVO: o objetivo deste estudo foi avaliar a força liberada por diferentes fios de níquel-titânio (NiTi superelástico em deslocamento vertical, a fim de determinar se a liberação de estresse por esses satisfaz o critério de forças suaves e constantes, geralmente atribuído a tais arcos. MÉTODOS: dez amostras de seis arcos de NiTi superelástico 0,016” de marcas comerciais diferentes (Ormco, GAC, Morelli, TP, American Orthodontics e Rocky Mountain foram testados em um modelo metálico usando braquetes Dynalock (3M Unitek. Na região do canino, havia um braquete móvel conectado a uma haste, a qual estava relacionada com uma célula de carga de 0,5kg de uma máquina universal de ensaios (Autograph AG-199kNG, Shimadzu. O deslocamento do conjunto na região do canino foi realizado a uma velocidade constante de 0,5mm/min e o deslocamento máximo foi de 1,0mm. O conjunto foi submerso em água com temperatura controlada a 37ºC. RESULTADOS: os resultados obtidos foram avaliados por ANOVA (p <0,05, usando o software SAS System 8.02, Cry, NC, EUA. O arco da TP apresentou a menor força durante todo o

The preparation of titanium-vanadium carbide/nickel cermets. Technical report

International Nuclear Information System (INIS)

Precht, W.; Sprissler, B.

1976-01-01

Titanium/vanadium alloy carbide rods were prepared by a zone melting procedure. Wetting studies were carried out using sections of the fused rods and candidate matrix material. It was established that nickel exhibits excellent wetting of (Ti, V) C, and accordingly cermet blends were prepared and liquid phase sintered. Processing parameters are discussed as well as their effect on the final microstructure. Alternate methods for cermet preparation are offered which use as received titanium carbide and vanadium carbide powders

Nickel-Titanium Single-file System in Endodontics.

Science.gov (United States)

Dagna, Alberto

2015-10-01

This work describes clinical cases treated with a innovative single-use and single-file nickel-titanium (NiTi) system used in continuous rotation. Nickel-titanium files are commonly used for root canal treatment but they tend to break because of bending stresses and torsional stresses. Today new instruments used only for one treatment have been introduced. They help the clinician to make the root canal shaping easier and safer because they do not require sterilization and after use have to be discarded. A new sterile instrument is used for each treatment in order to reduce the possibility of fracture inside the canal. The new One Shape NiTi single-file instrument belongs to this group. One Shape is used for complete shaping of root canal after an adequate preflaring. Its protocol is simple and some clinical cases are presented. It is helpful for easy cases and reliable for difficult canals. After 2 years of clinical practice, One Shape seems to be helpful for the treatment of most of the root canals, with low risk of separation. After each treatment, the instrument is discarded and not sterilized in autoclave or re-used. This single-use file simplifies the endodontic therapy, because only one instrument is required for canal shaping of many cases. The respect of clinical protocol guarantees predictable good results.

A clinical study of space closure with nickel-titanium closed coil springs and an elastic module.

Science.gov (United States)

Samuels, R H; Rudge, S J; Mair, L H

1998-07-01

A previous study has shown that a 150-gram nickel-titanium closed coil spring (Sentalloy, GAC International Inc.) closed spaces more quickly and more consistently than an elastic module (Alastik, Unitec/3M). This study used the same friction sensitive sliding mechanics of pitting the six anterior teeth against the second bicuspid and first molars, to examine the rate of space closure of 100-gram and 200-gram nickel-titanium closed coil springs. The results for the three springs and elastic module were compared. The nickel-titanium closed coil springs produced a more consistent space closure than the elastic module. The 150- and 200-gram springs produced a faster rate of space closure than the elastic module or the 100-gram spring. No significant difference was noted between the rates of closure for the 150- and the 200-gram springs.

Cytotoxic, allergic and genotoxic activity of a nickel-titanium alloy

NARCIS (Netherlands)

Veldhuizen, AG; Sanders, MM; Schakenraad, JM; vanHorn, [No Value

The nearly equiatomic nickel-titanium (NiTi) alloy is known for its shape memory properties. These properties can be put to excellent use in various biomedical applications, such as wires for orthodontic tooth alignment and osteosynthesis staples. The aim of this study was to evaluate the short-term

Angular deflection of rotary nickel titanium files: a comparative study

Directory of Open Access Journals (Sweden)

Gianluca Gambarini

2009-12-01

Full Text Available A new manufacturing method of twisting nickel titanium wire to produce rotary nickel titanium (RNT files has recently been developed. The aim of the present study was to evaluate whether the new manufacturing process increased the angular deflection of RNT files, by comparing instruments produced using the new manufacturing method (Twisted Files versus instruments produced with the traditional grinding process. Testing was performed on a total of 40 instruments of the following commercially available RNT files: Twisted Files (TF, Profile, K3 and M2 (NRT. All instruments tested had the same dimensions (taper 0.06 and tip size 25. Test procedures strictly followed ISO 3630-1. Data were collected and statistically analyzed by means ANOVA test. The results showed that TF demonstrated significantly higher average angular deflection levels (P<0.05, than RNT manufactured by a grinding process. Since angular deflection represent the amount of rotation (and consequently deformation that a RNT file can withstand before torsional failure, such a significant improvement is a favorable property for the clinical use of the tested RNT files.

Diffusion of titanium and nickel in B2 NiTi

Czech Academy of Sciences Publication Activity Database

Divinski, S.V.; Stloukal, Ivo; Král, Lubomír; Herzig, Ch.

289-292, - (2009), s. 377-382 ISSN 1012-0386. [DIMAT 2008, International Conference on Diffusion in Materials /7./. Lanzarote, Canary Islands , 28.10.2008-31.10.2008] Institutional research plan: CEZ:AV0Z20410507 Keywords : intermetallic compound NiTi * nickel nad titanium diffusion * diffusion mechanism Subject RIV: BJ - Thermodynamics http://www.scientific.net/DDF.289-292.377/

The Effect of Pre-Stressing on the Static Indentation Load Capacity of the Superelastic 60NiTi

Science.gov (United States)

DellaCorte, Christopher; Moore, Lewis E., III; Clifton, Joshua S.

2013-01-01

Superelastic nickel-titanium alloys, such as 60NiTi (60Ni-40Ti by wt.%), are under development for use in mechanical components like rolling element bearings and gears. Compared to traditional bearing steels, these intermetallic alloys, when properly heat-treated, are hard but exhibit much lower elastic modulus (approx.100 GPa) and a much broader elastic deformation range (approx.3 percent or more). These material characteristics lead to high indentation static load capacity, which is important for certain applications especially space mechanisms. To ensure the maximum degree of elastic behavior, superelastic materials must be pre-stressed, a process referred to as "training" in shape memory effect (SME) terminology, at loads and stresses beyond expected use conditions. In this paper, static indentation load capacity tests are employed to assess the effects of pre-stressing on elastic response behavior of 60NiTi. The static load capacity is measured by pressing 12.7 mm diameter ceramic Si3N4 balls into highly polished, hardened 60NiTi flat plates that have previously been exposed to varying levels of pre-stress (up to 2.7 GPa) to determine the load that results in shallow but measurable (0.6 m, 25 in. deep) permanent dents. Hertz stress calculations are used to estimate contact stress. Without exposure to pre-stress, the 60NiTi surface can withstand an approximately 3400 kN load before significant denting (>0.4 m deep) occurs. When pre-stressed to 2.7 GPa, a static load of 4900 kN is required to achieve a comparable dent, a 30 percent increase. These results suggest that stressing contact surfaces prior to use enhances the static indentation load capacity of the superelastic 60NiTi. This approach may be adaptable to the engineering and manufacture of highly resilient mechanical components such as rolling element bearings.

Deflection and Flexural Strength Effects on the Roughness of Aesthetic-Coated Orthodontic Wires

OpenAIRE

Albuquerque, Cibele Gonçalves de; Correr, Américo Bortolazzo; Venezian, Giovana Cherubini; Santamaria Jr, Milton; Tubel, Carlos Alberto; Vedovello, Silvia Amélia Scudeler

2017-01-01

Abstract The aim was to evaluate the flexural strength and the effects of deflection on the surface roughness of esthetic orthodontic wires. The sample consisted of 70 archwire 0.014-inch: polytetrafluorethylene (PTFE)-coated Nickel-Titanium (Niti) archwires (Titanol Cosmetic-TC, Flexy Super Elastic Esthetic-FSE, esthetic Nickel Titanium Wire-ANT); epoxy resin-coated Niti archwires (Spectra-S, Niticosmetic-TEC); gold and rhodium coated Niti (Sentalloy-STC) and a control group (superelastic Ni...

Shape memory behavior of single and polycrystalline nickel rich nickel titanium alloys

Science.gov (United States)

Kaya, Irfan

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 Ni 51Ti49 (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 Ni 51Ti49 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

Absolute cross section measurement for the ionization of the K-shell of titanium and nickel by electron impact (50 KEV)

International Nuclear Information System (INIS)

Jessenberger, J.

1974-01-01

The yield of characteristic X-ray K radiation of titanium during bombardment with electrons in the energy region of 6-50 keV and of nickel at 9-50 keV was measured, and the cross sections for th ionization of the K shell of titanium and nickel were determined from this. The results obtained are compared with several theoretical models. (WL/LN) [de

Preference of undergraduate students after first experience on nickel-titanium endodontic instruments

Directory of Open Access Journals (Sweden)

Sang Won Kwak

2016-08-01

Full Text Available Objectives This study aimed to compare two nickel-titanium systems (rotary vs. reciprocating for their acceptance by undergraduate students who experienced nickel-titanium (NiTi instruments for the first time. Materials and Methods Eighty-one sophomore dental students were first taught on manual root canal preparation with stainless-steel files. After that, they were instructed on the use of ProTaper Universal system (PTU, Dentsply Maillefer, then the WaveOne (WO, Dentsply Maillefer. They practiced with each system on 2 extracted molars, before using those files to shape the buccal or mesial canals of additional first molars. A questionnaire was completed after using each file system, seeking students' perception about 'Ease of use', 'Flexibility', 'Cutting-efficiency', 'Screwing-effect', 'Feeling-safety', and 'Instrumentation-time' of the NiTi files, relative to stainless-steel instrumentation, on a 5-point Likert-type scale. They were also requested to indicate their preference between the two systems. Data was compared between groups using t-test, and with Chi-square test for correlation of each perception value with the preferred choice (p = 0.05. Results Among the 81 students, 55 indicated their preferred file system as WO and 22 as PTU. All scores were greater than 4 (better for both systems, compared with stainless-steel files, except for 'Screwing-effect' for PTU. The scores for WO in the categories of 'Flexibility', 'Screwing-effect', and 'Feeling-safety' were significantly higher scores than those of PTU. A significant association between the 'Screwing-effect' and students' preference for WO was observed. Conclusions Novice operators preferred nickel-titanium instruments to stainless-steel, and majority of them opted for reciprocating file instead of continuous rotating system.

Grain-resolved analysis of localized deformation in nickel-titanium wire under tensile load.

Science.gov (United States)

Sedmák, P; Pilch, J; Heller, L; Kopeček, J; Wright, J; Sedlák, P; Frost, M; Šittner, P

2016-08-05

The stress-induced martensitic transformation in tensioned nickel-titanium shape-memory alloys proceeds by propagation of macroscopic fronts of localized deformation. We used three-dimensional synchrotron x-ray diffraction to image at micrometer-scale resolution the grain-resolved elastic strains and stresses in austenite around one such front in a prestrained nickel-titanium wire. We found that the local stresses in austenite grains are modified ahead of the nose cone-shaped buried interface where the martensitic transformation begins. Elevated shear stresses at the cone interface explain why the martensitic transformation proceeds in a localized manner. We established the crossover from stresses in individual grains to a continuum macroscopic internal stress field in the wire and rationalized the experimentally observed internal stress field and the topology of the macroscopic front by means of finite element simulations of the localized deformation. Copyright © 2016, American Association for the Advancement of Science.

Load Deflection Characteristics of Nickel Titanium Initial Archwires

Directory of Open Access Journals (Sweden)

Hossein Aghili

2016-05-01

Full Text Available Objectives: The aim of this study was to assess and compare the characteristics of commonly used initial archwires by their load deflection graphs.Materials and Methods: This study tested three wire designs namely copper nickel titanium (CNT, nickel titanium (NiTi, and multi-strand NiTi (MSNT archwires engaged in passive self-ligating (PSL brackets, active self-ligating (ASL brackets or conventional brackets. To evaluate the mechanical characteristics of the specimens, a three-point bending test was performed. The testing machine vertically applied force on the midpoint of the wire between the central incisor and canine teeth to obtain 2 and 4mm of deflection. The force level at maximum deflection and characteristics of plateau (the average plateau load and the plateau length were recorded. Two-way ANOVA and Tukey’s test were used at P <0.05 level of significance.Results: Force level at maximum deflection and plateau length were significantly affected by the amount of deflection. The type of archwires and brackets had significant effects on force level at maximum deflection, and plateau length. However, the bracket type had no significant effect on the average plateau force.Conclusion: With any type of brackets in deflections of 2 and 4mm, MSNT wire exerted the lowest while NiTi wire exerted the highest force level at maximum deflection and plateau phase. The force level at maximum deflection and the plateau length increased with raising the amount of primary deflection; however the average plateau force did not change significantly.

A comparison of torque expression between stainless steel, titanium molybdenum alloy, and copper nickel titanium wires in metallic self-ligating brackets.

Science.gov (United States)

Archambault, Amy; Major, Thomas W; Carey, Jason P; Heo, Giseon; Badawi, Hisham; Major, Paul W

2010-09-01

The force moment providing rotation of the tooth around the x-axis (buccal-lingual) is referred to as torque expression in orthodontic literature. Many factors affect torque expression, including the wire material characteristics. This investigation aims to provide an experimental study into and comparison of the torque expression between wire types. With a worm-gear-driven torquing apparatus, wire was torqued while a bracket mounted on a six-axis load cell was engaged. Three 0.019 x 0.0195 inch wire (stainless steel, titanium molybdenum alloy [TMA], copper nickel titanium [CuNiTi]), and three 0.022 inch slot bracket combinations (Damon 3MX, In-Ovation-R, SPEED) were compared. At low twist angles (wires were not statistically significant. At twist angles over 24 degrees, stainless steel wire yielded 1.5 to 2 times the torque expression of TMA and 2.5 to 3 times that of nickel titanium (NiTi). At high angles of torsion (over 40 degrees) with a stiff wire material, loss of linear torque expression sometimes occurred. Stainless steel has the largest torque expression, followed by TMA and then NiTi.

Alleviation of mandibular anterior crowding with copper-nickel-titanium vs nickel-titanium wires: a double-blind randomized control trial.

Science.gov (United States)

Pandis, Nikolaos; Polychronopoulou, Argy; Eliades, Theodore

2009-08-01

The purpose of this study was to investigate the efficiency of copper-nickel-titanium (CuNiTi) vs nickel-titanium (NiTi) archwires in resolving crowding of the anterior mandibular dentition. Sixty patients were included in this single-center, single-operator, double-blind randomized trial. All patients were bonded with the In Ovation-R self-ligating bracket (GAC, Central Islip, NY) with a 0.022-in slot, and the amount of crowding of the mandibular anterior dentition was assessed by using the irregularity index. The patients were randomly allocated into 2 groups of 30 patients, each receiving a 0.016-in CuNiTi 35 degrees C (Ormco, Glendora, Calif) or a 0.016-in NiTi (ModernArch, Wyomissing, Pa) wire. The type of wire selected for each patient was not disclosed to the provider or the patient. The date that each patient received a wire was recorded, and all patients were followed monthly for a maximum of 6 months. Demographic and clinical characteristics between the 2 wire groups were compared with the t test or the chi-square test and the Fisher exact test. Time to resolve crowding was explored with statistical methods for survival analysis, and alignment rate ratios for wire type and crowding level were calculated with Cox proportional hazards multivariate modeling. The type of wire (CuNiTi vs NiTi) had no significant effect on crowding alleviation (129.4 vs 121.4 days; hazard ratio, 1.3; P >0.05). Severe crowding (>5 on the irregularity index) showed a significantly higher probability of crowding alleviation duration relative to dental arches with a score of wires in laboratory and clinical conditions might effectively eliminate the laboratory-derived advantage of CuNiTi wires.

Influence of Cyclic Flexural Deformation on the Torsional Resistance of Controlled Memory and Conventional Nickel-titanium Instruments.

Science.gov (United States)

Acosta, Eufemia Carolina Peláez; Resende, Pedro Damas; Peixoto, Isabella Faria da Cunha; Pereira, Érika Sales Joviano; Buono, Vicente Tadeu Lopes; Bahia, Maria Guiomar de Azevedo

2017-04-01

The aim of this study was to evaluate the influence of cyclic deformation on the torsional resistance of controlled memory (CM) nickel-titanium files in comparison with superelastic (SE) instruments with similar geometric and dimensional characteristics. New 30/.06 HyFlex (HF; Coltene/Whaledent, Inc, Cuyahoga Falls, OH), Typhoon (Clinician's Choice Dental Products, New Milford, CT), RaCe (FKG, La-Chaux De Fonds, Switzerland), and ProTaper Universal F2 instruments (F2; Dentsply Maillefer, Ballaigues, Switzerland) were assessed. The diameter and pitch length were measured along the active part of the instruments. The number of cycles to failure (Nf) in flexural fatigue and the torsional resistance were evaluated for new files (n = 10). Ten new instruments of each type were fatigued to 3/4 of their fatigue life and then submitted to torsion until rupture. Data were analyzed using 1-way analysis of variance (α = .05). New CM files had a significantly higher Nf when compared with SE instruments; HF exhibited the highest value (P = .001). The mean torque value for F2 was the highest (P = .001). CM files precycled to 3/4 Nf had a significantly lower torque than the new files (HF: P = .003, Typhoon: P = .001), whereas the SE instruments displayed no significant differences (F2: P = .059, RaCe: P = .079). Cyclic flexural loading significantly reduced the torsional resistance of CM instruments. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Nickel-titanium wire in circumferential suture of a flexor tendon repair: a comparison to polypropylene.

Science.gov (United States)

Karjalainen, T; He, M; Chong, A K S; Lim, A Y T; Ryhanen, J

2010-07-01

Nickel-titanium (NiTi) has been proposed as an alternative material for flexor tendon core suture. To our knowledge, its suitability as a circumferential suture of flexor tendon repair has not been investigated before. The purpose of this ex vivo study was to investigate the biomechanical properties of NiTi circumferential repairs and to compare them with commonly used polypropylene. Forty porcine flexor tendons were cut and repaired by simple running or interlocking mattress technique using 100 microm NiTi wire or 6-0 polypropylene. The NiTi circumferential repairs showed superior stiffness, gap resistance, and load to failure when compared to polypropylene repairs with both techniques. Nickel-titanium wire seems to be a potential material for circumferential repair of flexor tendons. Copyright 2010 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Evaluation and comparison of shear bond strength of porcelain to a beryllium-free alloy of nickel-chromium, nickel and beryllium free alloy of cobalt-chromium, and titanium: An in vitro study

Directory of Open Access Journals (Sweden)

Ananya Singh

2017-01-01

Conclusion: It could be concluded that newer nickel and beryllium free Co-Cr alloys and titanium alloys with improved strength to weight ratio could prove to be good alternatives to the conventional nickel-based alloys when biocompatibility was a concern.

Corrosion behavior of ion implanted nickel-titanium orthodontic wire in fluoride mouth rinse solutions.

Science.gov (United States)

Iijima, Masahiro; Yuasa, Toshihiro; Endo, Kazuhiko; Muguruma, Takeshi; Ohno, Hiroki; Mizoguchi, Itaru

2010-01-01

This study investigated the corrosion properties of ion implanted nickel-titanium wire (Neo Sentalloy Ionguard) in artificial saliva and fluoride mouth rinse solutions (Butler F Mouthrinse, Ora-Bliss). Non ion implanted nickel-titanium wire (Neo Sentalloy) was used as control. The anodic corrosion behavior was examined by potentiodynamic polarization measurement. The surfaces of the specimens were examined with SEM. The elemental depth profiles were characterized by XPS. Neo Sentalloy Ionguard in artificial saliva and Butler F Mouthrinse (500 ppm) had a lower current density than Neo Sentalloy. In addition, breakdown potential of Neo Sentalloy Ionguard in Ora-Bliss (900 ppm) was much higher than that of Neo Sentalloy although both wires had similar corrosion potential in Ora-Bliss (450 and 900 ppm). The XPS results for Neo Sentalloy Ionguard suggested that the layers consisted of TiO(2) and TiN were present on the surface and the layers may improve the corrosion properties.

Mechanical and Metallurgical Properties of Various Nickel-Titanium Rotary Instruments

OpenAIRE

Shim, Kyu-Sang; Oh, Soram; Kum, KeeYeon; Kim, Yu-Chan; Jee, Kwang-Koo; Chang, Seok Woo

2017-01-01

The aim of this study was to investigate the effect of thermomechanical treatment on mechanical and metallurgical properties of nickel-titanium (NiTi) rotary instruments. Eight kinds of NiTi rotary instruments with sizes of ISO #25 were selected: ProFile, K3, and One Shape for the conventional alloy; ProTaper NEXT, Reciproc, and WaveOne for the M-wire alloy; HyFlex CM for the controlled memory- (CM-) wire; and TF for the R-phase alloy. Torsional fracture and cyclic fatigue fracture tests were...

Evaluation of anomalies during nickel and titanium silicide formation using the effective heat of formation mode

CSIR Research Space (South Africa)

Pretorius, R

1993-11-01

Full Text Available , as well as the observed sequence of growth of different silicide phases, are not in agree- ment with thermodynamic considerations [26]. In the case of the nickel silicides Ni,Si is nearly always found to be the first... to determine how the oxygen content in the silicon affects phase formation. We also show how the anomalous behaviour of titanium and nickel silicide formation can be explained thermodynamically by using the ?effective heat...

Interfacial microstructure and mechanical properties of diffusion-bonded titanium-stainless steel joints using a nickel interlayer

International Nuclear Information System (INIS)

Kundu, S.; Chatterjee, S.

2006-01-01

Diffusion bonding was carried out between commercially pure titanium and 304 stainless steel using nickel interlayer in the temperature range of 800-950 deg. C for 3.6 ks under 3 MPa load in vacuum. The transition joints thus formed were characterized in optical and scanning electron microscopes. TiNi 3 , TiNi and Ti 2 Ni are formed at the nickel-titanium (Ni-Ti) interface; whereas, stainless steel-nickel (SS-Ni) interface is free from intermetallic compounds up to 900 deg. C processing temperatures. At 950 deg. C, Ni-Ti interface exhibits the presence of β-Ti discrete islands in the matrix of Ti 2 Ni and the phase mixture of λ + χ + α-Fe, λ + α-Fe, λ + FeTi + β-Ti and FeTi + β-Ti occurs at the stainless steel-nickel interface. Nickel is able to inhibit the diffusion of Ti to stainless steel side up to 900 deg. C temperature; however, becomes unable to restrict the migration of Ti to stainless steel at 950 deg. C. Bond strength was also evaluated and maximum tensile strength of ∼302 MPa and shear strength of ∼219 MPa were obtained for the diffusion couple processed at 900 deg. C temperature due to better contact of the mating surfaces and failure takes place at the Ni-Ti interface. At higher joining temperature, the formation of Fe-Ti bases intermetallics reduces the bond strength and failure occurs at the SS-Ni interface

The ability of different nickel-titanium rotary instruments to induce dentinal damage during canal preparation

NARCIS (Netherlands)

Bier, C.A.S.; Shemesh, H.; Tanomaru-Filho, M.; Wesselink, P.R.; Wu, M.K.

2009-01-01

The purpose of this study was to compare the incidence of dentinal defects (fractures and craze lines) after canal preparation with different nickel-titanium rotary files. Two hundred sixty mandibular premolars were selected. Forty teeth were left unprepared (n = 40). The other teeth were prepared

Endodontic complications of root canal therapy performed by dental students with stainless-steel K-files and nickel-titanium hand files.

Science.gov (United States)

Pettiette, M T; Metzger, Z; Phillips, C; Trope, M

1999-04-01

Straightening of curved canals is one of the most common procedural errors in endodontic instrumentation. This problem is commonly encountered when dental students perform molar endodontics. The purpose of this study was to compare the effect of the type of instrument used by these students on the extent of straightening and on the incidence of other endodontic procedural errors. Nickel-titanium 0.02 taper hand files were compared with traditional stainless-steel 0.02 taper K-files. Sixty molar teeth comprised of maxillary and mandibular first and second molars were treated by senior dental students. Instrumentation was with either nickel-titanium hand files or stainless-steel K-files. Preoperative and postoperative radiographs of each tooth were taken using an XCP precision instrument with a customized bite block to ensure accurate reproduction of radiographic angulation. The radiographs were scanned and the images stored as TIFF files. By superimposing tracings from the preoperative over the postoperative radiographs, the degree of deviation of the apical third of the root canal filling from the original canal was measured. The presence of other errors, such as strip perforation and instrument breakage, was established by examining the radiographs. In curved canals instrumented by stainless-steel K-files, the average deviation of the apical third of the canals was 14.44 degrees (+/- 10.33 degrees). The deviation was significantly reduced when nickel-titanium hand files were used to an average of 4.39 degrees (+/- 4.53 degrees). The incidence of other procedural errors was also significantly reduced by the use of nickel-titanium hand files.

Cyclic fatigue resistance of newly manufactured rotary nickel titanium instruments used in different rotational directions.

Science.gov (United States)

Gambarini, Gianlucca; Gergi, Richard; Grande, Nicola Maria; Osta, Nada; Plotino, Gianluca; Testarelli, Luca

2013-12-01

The aim of this study was to investigate whether cyclic fatigue resistance is increased for nickel titanium instruments manufactured with improved heating processes in clockwise or counterclockwise continuous rotation. The instruments compared were produced either using the R-phase heat treatment (K3XF; SybronEndo, Orange, CA, USA) or the M-wire alloy (ProFile Vortex; DENTSPLY Tulsa Dental Specialties, Tulsa, OK, USA). Tests were performed with a specific cyclic fatigue device that evaluated cycles to failure of rotary instruments in curved artificial canals. Results indicated no significant difference in resistance to cyclic fatigue when rotary nickel titanium instruments are used in clockwise or counterclockwise continuous rotation. In both directions of rotation, size 04-25 K3XF showed a significant increase (P < 0.05) in the mean number of cycles to failure when compared with size 04-25 ProFile Vortex. © 2012 The Authors. Australian Endodontic Journal © 2012 Australian Society of Endodontology.

Fatigue resistance of engine-driven rotary nickel-titanium instruments produced by new manufacturing methods.

Science.gov (United States)

Gambarini, Gianluca; Grande, Nicola Maria; Plotino, Gianluca; Somma, Francesco; Garala, Manish; De Luca, Massimo; Testarelli, Luca

2008-08-01

The aim of the present study was to investigate whether cyclic fatigue resistance is increased for nickel-titanium instruments manufactured by using new processes. This was evaluated by comparing instruments produced by using the twisted method (TF; SybronEndo, Orange, CA) and those using the M-wire alloy (GTX; Dentsply Tulsa-Dental Specialties, Tulsa, OK) with instruments produced by a traditional NiTi grinding process (K3, SybronEndo). Tests were performed with a specific cyclic fatigue device that evaluated cycles to failure of rotary instruments inside curved artificial canals. Results indicated that size 06-25 TF instruments showed a significant increase (p 0.05) in the mean number of cycles to failure when compared with size 06-20 GT series X instruments. The new manufacturing process produced nickel-titanium rotary files (TF) significantly more resistant to fatigue than instruments produced with the traditional NiTi grinding process. Instruments produced with M-wire (GTX) were not found to be more resistant to fatigue than instruments produced with the traditional NiTi grinding process.

Interlot variations of transition temperature range and force delivery in copper-nickel-titanium orthodontic wires.

Science.gov (United States)

Pompei-Reynolds, Renée C; Kanavakis, Georgios

2014-08-01

The manufacturing process for copper-nickel-titanium archwires is technique sensitive. The primary aim of this investigation was to examine the interlot consistency of the mechanical properties of copper-nickel-titanium wires from 2 manufacturers. Wires of 2 sizes (0.016 and 0.016 × 0.022 in) and 3 advertised austenite finish temperatures (27°C, 35°C, and 40°C) from 2 manufacturers were tested for transition temperature ranges and force delivery using differential scanning calorimetry and the 3-point bend test, respectively. Variations of these properties were analyzed for statistical significance by calculating the F statistic for equality of variances for transition temperature and force delivery in each group of wires. All statistical analyses were performed at the 0.05 level of significance. Statistically significant interlot variations in austenite finish were found for the 0.016 in/27°C (P = 0.041) and 0.016 × 0.022 in/35°C (P = 0.048) wire categories, and in austenite start for the 0.016 × 0.022 in/35°C wire category (P = 0.01). In addition, significant variations in force delivery were found between the 2 manufacturers for the 0.016 in/27°C (P = 0.002), 0.016 in/35.0°C (P = 0.049), and 0.016 × 0.022 in/35°C (P = 0.031) wires. Orthodontic wires of the same material, dimension, and manufacturer but from different production lots do not always have similar mechanical properties. Clinicians should be aware that copper-nickel-titanium wires might not always deliver the expected force, even when they come from the same manufacturer, because of interlot variations in the performance of the material. Copyright © 2014 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Influence of Nitinol wire surface treatment on oxide thickness and composition and its subsequent effect on corrosion resistance and nickel ion release.

Science.gov (United States)

Clarke, B; Carroll, W; Rochev, Y; Hynes, M; Bradley, D; Plumley, D

2006-10-01

Medical implants and devices are now used successfully in surgical procedures on a daily basis. Alloys of nickel and titanium, and in particular Nitinol are of special interest in the medical device industry, because of their shape memory and superelastic properties. The corrosion behavior of nitinol in the body is also of critical importance because of the known toxicological effects of nickel. The stability of a NiTi alloy in the physiological environment is dependant primarily on the properties of the mostly TiO(2) oxide layer that is present on the surface. For the present study, a range of nitinol wires have been prepared using different drawing processes and a range of surface preparation procedures. It is clear from the results obtained that the wire samples with very thick oxides also contain a high nickel content in the oxide layer. The untreated samples with the thicker oxides show the lowest pitting potential values and greater nickel release in both long and short-term experiments. It was also found that after long-term immersion tests breakdown potentials increased for samples that exhibited lower values initially. From these results it would appear that surface treatment is essential for the optimum bioperformance of nitinol. (c) 2006 Wiley Periodicals, Inc

A bridge column with superelastic NiTi SMA and replaceable rubber hinge for earthquake damage mitigation

Science.gov (United States)

Varela, Sebastian; ‘Saiid' Saiidi, M.

2016-07-01

This paper reports a unique concept for resilient bridge columns that can undergo intense earthquake loading and remain functional with minimal damage and residual drift. In this concept, the column is designed so that its components can be easily disassembled and reassembled to facilitate material recycling and component reuse. This is meant to foster sustainability of bridge systems while minimizing monetary losses from earthquakes. Self-centering and energy dissipation in the column were provided by unbonded superelastic nickel-titanium (NiTi) shape memory alloy bars placed inside a plastic hinge element made of rubber. This replaceable plastic hinge was in turn attached to a concrete-filled carbon fiber-reinforced polymer tube and a precast concrete footing that were designed to behave elastically. The proposed concept was evaluated experimentally by testing a ¼-scale column model under simulated near-fault earthquake motions on a shake table. After testing, the model was disassembled, reassembled and tested again. The seismic performance of the reassembled model was found to be comparable to that of the ‘virgin’ model. A relatively simple computational model of the column tested that was developed in OpenSees was able to match some of the key experimental response parameters.

Cyclic Fatigue Testing of Three Different Rotary Nickel Titanium Endodontic Instruments in Simulated Curved Canals - An in Vitro Sem Analysis

OpenAIRE

Reddy Y., Pallavi; S., Kavita; Subbarao, C.V.

2014-01-01

Introduction: Instrument separation is a serious concern in endodontics. Stainless steel instruments usually deform before they separate whereas Nickel Titanium instruments do not show any sign of deformation.

Evaluation of the lower incisor inclination during alignment and leveling using superelastic NiTi archwires: a laboratory study

Directory of Open Access Journals (Sweden)

Carolina Baratieri

2012-06-01

Full Text Available OBJECTIVE: The aim of this laboratory study is to evaluate the influence of the shape and the length limitation of superelastic nickel-titanium (NiTi archwires on lower incisors inclination during alignment and leveling. METHODS: Metal teeth mounted on a typodont articulator device were used to simulate a malocclusion of the mandibular arch (-3.5 mm model discrepancy. Three different shapes (Standard, Accuform and Ideal of superelastic NiTi archwires (Sentalloy, GAC, USA were tested. Specimens were divided in two groups: Group I, with no limitation of the archwire length; and Group II, with distal limitation. Each group had thirty specimens divided into three subgroups differentiated by the archwire shape. All groups used round wires with diameters of 0.014-in, 0.016-in, 0.018-in and 0.020-in. The recording of all intervals was accomplished using standardized digital photographs with orthogonal norm in relation to median sagittal plane. The buccolingual inclination of the incisor was registered using photographs and software CorelDraw. RESULTS: The results were obtained using ANOVA and Tukey's test at a significant level of 5%. The inclination of the lower incisor increased in both groups and subgroups. The shape of the archwire had statistically significant influence only in Group I - Standard (11.76º, Ideal (5.88º and Accuform (1.93º. Analyzing the influence of the length limitation, despite the mean incisor tipping in Group II (3.91º had been smaller than Group I (6.52º, no statistically significant difference was found, except for Standard, 3.89º with limitation and 11.76º without limitation. The greatest incisor tipping occurred with the 0.014-in archwires.

Self-organized nickel nanoparticles on nanostructured silicon substrate intermediated by a titanium oxynitride (TiNxOy) interface

Science.gov (United States)

Morales, M.; Droppa, R., Jr.; de Mello, S. R. S.; Figueroa, C. A.; Zanatta, A. R.; Alvarez, F.

2018-01-01

In this work we report an experimental approach by combining in situ sequential top-down and bottom-up processes to induce the organization of nanosized nickel particles. The top-down process consists in xenon ion bombardment of a crystalline silicon substrate to generate a pattern, followed by depositing a ˜15 nm titanium oxynitride thin film to act as a metallic diffusion barrier. Then, metallic nanoparticles are deposited by argon ion sputtering a pure nickel target, and the sample is annealed to promote the organization of the nickel nanoparticles (a bottom-up process). According to the experimental results, the surface pattern and the substrate biaxial surface strain are the driving forces behind the alignment and organization of the nickel nanoparticles. Moreover, the ratio between the F of metallic atoms arriving at the substrate relative to its surface diffusion mobility determines the nucleation regime of the nickel nanoparticles. These features are presented and discussed considering the existing technical literature on the subject.

Influence of bending mode on the mechanical properties of nickel-titanium archwires and correlation to differential scanning calorimetry measurements.

Science.gov (United States)

Brauchli, Lorenz M; Keller, Heidi; Senn, Christiane; Wichelhaus, Andrea

2011-05-01

Nickel-titanium orthodontic archwires are used with bonded appliances for initial leveling. However, precise bending of these archwires is difficult and can lead to changes within the crystal structure of the alloy, thus changing the mechanical properties unpredictably. The aim of this study was to evaluate different bending methods in relation to the subsequent mechanical characteristics of the alloy. The mechanical behaviors of 3 archwires (Copper NiTi 35°C [Ormco, Glendora, Calif], Neo Sentalloy F 80 [GAC International, Bohemia, NY], and Titanol Low Force [Forestadent, Pforzheim, Germany]) were investigated after heat-treatment in a dental furnace at 550-650°C, treatment with an electrical current (Memory-Maker, Forestadent), and cold forming. In addition, the change in A(f) temperature was registered by means of differential scanning calorimetry. Heat-treatment in the dental furnace as well as with the Memory-Maker led to widely varying force levels for each product. Cold forming resulted in similar or slightly reduced force levels when compared to the original state of the wires. A(f) temperatures were in general inversely proportional to force levels. Archwire shape can be modified by using either chair-side technique (Memory-Maker, cold forming) because the superelastic behavior of the archwires is not strongly affected. However it is important to know the specific changes in force levels induced for each individual archwire with heat-treatment. Cold forming resulted in more predictable forces for all products tested. Therefore, cold forming is recommended as a chair-side technique for the shaping of NiTi archwires. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Nickel titanium T-loop wire dimensions for en masse retraction.

Science.gov (United States)

Almeida, Layene; Ribeiro, Alexandre; Parsekian Martins, Renato; Viecilli, Rodrigo; Parsekian Martins, Lídia

2016-09-01

To compare the force system produced by nickel-titanium T-loop springs made with wires of different dimensions. Thirty compound T-loop springs were divided into three groups according to the dimensions of the nickel-titanium wire used for its design: 0.016" × 0.022", 0.017" × 0.025", and 0.018" × 0.025". The loops were tested on the Orthodontic Force Tester machine at an interbracket distance of 23 mm and activated 9 mm. The force in the y-axis and the moment in the x-axis were registered while the calculated moment to force ratio was recorded at each .5 mm of deactivation. The data were analyzed by three analyses of variance of repeated measures to detect differences and interactions between deactivation and wire size on force, moment, and moment-force ratios (M/F). All groups had significantly different forces (P wire produced 1.78N of force while the 0.017" × 0.025" and the 0.018" × 0.025" produced 2.81 N and 3.25 N, respectively. The 0.016" × 0.022" wire produced lower moments (11.6 Nmm) than the 0.017" × 0.025" and 0.018" × 0.025" wires, which produced similar moments (13.9 Nmm and 14.4Nmm, respectively). The M/F produced was different for all groups; 0.016" × 0.022" T-loops produced 6.7 mm while the 0.017" × 0.025" and 0.018" × 0.025" T-loops produced 5.0 mm and 4.5 mm, respectively. An interaction was detected for all variables between deactivation and groups. The larger wires tested produced higher forces with slight increase on the moments, but the M/F produced by the 0.016" × 0.022" wire was the highest found.

Mechanical properties of nickel-titanium archwire used in the final treatment phase of Tip-Edge Plus technique: an in vitro study.

Science.gov (United States)

Shen, Xiao; Sun, Xin-hua; Tian, Hua; Zhang, Chun-bo; Yan, Kuo; Guo, Yong-liang

2013-01-01

As the only active component in final treatment phase of Tip-Edge Plus technique, the activation of nickel-titanium orthodontic archwires is one of the factors that affect the torque expression. It is necessary to evaluate the mechanical properties of the nickel-titanium wire used in the final treatment phase in simulated oral environments to forecast the treatment outcomes. The mechanical properties of 171 thermal nickel-titanium wires of 0.35 mm (0.014-in) in diameters with different deflection of 40 mm in length were investigated with three-point bending test. The samples were divided into 2 groups: as-received and bended groups. In the bended group, samples were divided into 7 subgroups according to the amounts of deflection and named by the canine angulations (-25°, -19°, -13°, -7°, -1°, +5°, +11°). The deflection of wires was made by inserting the wires into the deep tunnel of Tip-Edge Plus brackets positioned in plaster casts with different canine angulations to mimic the use of nickel-titanium wires in the final treatment phase. Immersed the bended group in artificial saliva (pH 6.8) and preserved at 37.0°C. Eight durations of incubation were tested: 1 to 8 weeks. Three analogous samples of each group and subgroups were tested per week. Stiffness (YS:E) and the load-deflection characteristics of unloading plateau section were obtained. Significant changes in specific mechanical properties were observed in long-term immersed and large deflected wires compared with as-received groups. Both immersion time and deflection affected the mechanical properties of wires in the simulated oral environment, and the two factors had synergistic effect. In groups -25°, -19° and -13°, stiffness (YS:E) increased then decreased and average plateau force and ratio of variance decreased then increased correspondingly at specific time. In the final treatment phase of Tip-Edge Plus technique, the mechanical properties of nickel-titanium wire are associated with the

The solidification velocity of nickel and titanium alloys

Science.gov (United States)

Altgilbers, Alex Sho

2002-09-01

The solidification velocity of several Ni-Ti, Ni-Sn, Ni-Si, Ti-Al and Ti-Ni alloys were measured as a function of undercooling. From these results, a model for alloy solidification was developed that can be used to predict the solidification velocity as a function of undercooling more accurately. During this investigation a phenomenon was observed in the solidification velocity that is a direct result of the addition of the various alloying elements to nickel and titanium. The additions of the alloying elements resulted in an additional solidification velocity plateau at intermediate undercoolings. Past work has shown a solidification velocity plateau at high undercoolings can be attributed to residual oxygen. It is shown that a logistic growth model is a more accurate model for predicting the solidification of alloys. Additionally, a numerical model is developed from simple description of the effect of solute on the solidification velocity, which utilizes a Boltzmann logistic function to predict the plateaus that occur at intermediate undercoolings.

Tailoring superelasticity of soft magnetic materials

Science.gov (United States)

Cremer, Peet; Löwen, Hartmut; Menzel, Andreas M.

2015-10-01

Embedding magnetic colloidal particles in an elastic polymer matrix leads to smart soft materials that can reversibly be addressed from outside by external magnetic fields. We discover a pronounced nonlinear superelastic stress-strain behavior of such materials using numerical simulations. This behavior results from a combination of two stress-induced mechanisms: a detachment mechanism of embedded particle aggregates and a reorientation mechanism of magnetic moments. The superelastic regime can be reversibly tuned or even be switched on and off by external magnetic fields and thus be tailored during operation. Similarities to the superelastic behavior of shape-memory alloys suggest analogous applications, with the additional benefit of reversible switchability and a higher biocompatibility of soft materials.

Sonocatalytic injury of cancer cells attached on the surface of a nickel-titanium dioxide alloy plate.

Science.gov (United States)

Ninomiya, Kazuaki; Maruyama, Hirotaka; Ogino, Chiaki; Takahashi, Kenji; Shimizu, Nobuaki

2016-01-01

The present study demonstrates ultrasound-induced cell injury using a nickel-titanium dioxide (Ni-TiO2) alloy plate as a sonocatalyst and a cell culture surface. Ultrasound irradiation of cell-free Ni-TiO2 alloy plates with 1 MHz ultrasound at 0.5 W/cm(2) for 30s led to an increased generation of hydroxyl (OH) radicals compared to nickel-titanium (Ni-Ti) control alloy plates with and without ultrasound irradiation. When human breast cancer cells (MCF-7 cells) cultured on the Ni-TiO2 alloy plates were irradiated with 1 MHz ultrasound at 0.5 W/cm(2) for 30s and then incubated for 48 h, cell density on the alloy plate was reduced to approximately 50% of the controls on the Ni-Ti alloy plates with and without ultrasound irradiation. These results indicate the injury of MCF-7 cells following sonocatalytic OH radical generation by Ni-TiO2. Further experiments demonstrated cell shrinkage and chromatin condensation after ultrasound irradiation of MCF-7 cells attached on the Ni-TiO2 alloy plates, indicating induction of apoptosis. Copyright © 2015 Elsevier B.V. All rights reserved.

Influence of temperature of the short-period heat treatment on mechanical properties of the NiTi alloy

Directory of Open Access Journals (Sweden)

Jaroslav Čapek

2014-01-01

Full Text Available The equiatomic alloy of nickel and titanium, known as nitinol, possesses unique properties such as superelasticity, pseudoplasticity, shape memory, while maintaining good corrosion resistance and sufficient biocompatibility. Therefore it is used for production of various devices including surgery implants. Heat treatment of nickel-rich NiTi alloys can result in precipitation of nickel-rich phases, which strongly influence tensile and fatigue behaviour of the material.In this work we have studied influence of short-period heat treatment on tensile behaviour and fatigue life of the NiTi (50.9 at. % Ni wire intended for fabrication of surgery stents.

Deformation and fracture of Mtwo rotary nickel-titanium instruments after clinical use.

Science.gov (United States)

Inan, Ugur; Gonulol, Nihan

2009-10-01

In recent years, a number of rotary nickel titanium (NiTi) systems have been developed to provide better, faster, and easier cleaning and shaping of the root canal system. Although the NiTi instruments are more flexible than the stainless steel files, the main problem with the rotary NiTi instruments is the failure of the instruments. The aim of this study was to evaluate the deformation and fracture rate of Mtwo rotary nickel-titanium instruments (VDW, Munich, Germany) discarded after routine clinical use. A total of 593 Mtwo rotary NiTi instruments were collected after clinical use from the clinic of endodontics over 12 months. The length of the files was measured using a digital caliper to determine any fracture, and then all the files were evaluated under a stereomicroscope for defects such as unwinding, curving, or bending and fracture. The fracture faces of separated files were also evaluated under a scanning electron microscope. The data were analyzed using a chi-square and z test. A percentage of all files (25.80%) showed defects, and the major defect was fracture (16.02%). The most frequently fractured file was #10.04 (30.39%). Deformations without fracture were mostly observed on #15.05 files (25.47%). A higher rate of deformation was observed for #10.04 and #15.05 files. Therefore, these files should be considered as single-use instruments. Because cyclic fatigue was the cause of 71.58% of the instrument fractures, it is also important not to exceed the maximum number of usage recommended by the manufacturer and discard the instruments on a regular basis.

Shape memory effect and superelasticity of titanium nickelide alloys implanted with high ion doses

International Nuclear Information System (INIS)

Pogrebnjak, A D; Bratushka, S N; Beresnev, V M; Levintant-Zayonts, N

2013-01-01

The state of the art in ion implantation of superelastic NiTi shape memory alloys is analyzed. Various technological applications of the shape memory effect are outlined. The principles and techiques of ion implantation are described. Specific features of its application for modification of surface layers in surface engineering are considered. Key properties of shape memory alloys and problems in utilization of ion implantation to improve the surface properties of shape memory alloys, such as corrosion resistance, friction coefficient, wear resistance, etc. are discussed. The bibliography includes 162 references

Effect of autoclaving on the surfaces of TiN -coated and conventional nickel-titanium rotary instruments.

Science.gov (United States)

Spagnuolo, G; Ametrano, G; D'Antò, V; Rengo, C; Simeone, M; Riccitiello, F; Amato, M

2012-12-01

To evaluate the effects of repeated autoclave sterilization cycles on surface topography of conventional nickel-titanium ( NiTi ) and titanium nitride ( TiN )-coated rotary instruments. A total of 60 NiTi rotary instruments, 30 ProTaper (Dentsply Maillefer) and 30 TiN -coated AlphaKite (Komet/Gebr. Brasseler), were analysed. Instruments were evaluated in the as-received condition and after 1, 5 and 10 sterilization cycles. After sterilization, the samples were observed using scanning electron microscope (SEM), and surface chemical analysis was performed on each instrument with energy dispersive X-ray spectroscopy (EDS). Moreover, the samples were analysed by atomic force microscopy (AFM), and roughness average (Ra) and the root mean square value (RMS) of the scanned surface profiles were recorded. Data were analysed by means of anova followed by Tukey's test. Scanning electron microscope observations revealed the presence of pitting and deep milling marks in all instruments. EDS analysis confirmed that both types of instruments were composed mainly of nickel and titanium, whilst AlphaKite had additional nitride. After multiple autoclave sterilization cycles, SEM examinations revealed an increase in surface alterations, and EDS values indicated changes in chemical surface composition in all instruments. Ra and RMS values of ProTaper significantly increased after 5 (P = 0.006) and 10 cycles (P = 0.002) with respect to the as-received instruments, whilst AlphaKite showed significant differences compared with the controls after 10 cycles (P = 0.03). Multiple autoclave sterilization cycles modified the surface topography and chemical composition of conventional and TiN -coated NiTi rotary instruments. © 2012 International Endodontic Journal.

Evolution of Nickel-titanium Alloys in Endodontics.

Science.gov (United States)

Ounsi, Hani F; Nassif, Wadih; Grandini, Simone; Salameh, Ziad; Neelakantan, Prasanna; Anil, Sukumaran

2017-11-01

To improve clinical use of nickel-titanium (NiTi) endodontic rotary instruments by better understanding the alloys that compose them. A large number of engine-driven NiTi shaping instruments already exists on the market and newer generations are being introduced regularly. While emphasis is being put on design and technique, manufacturers are more discreet about alloy characteristics that dictate instrument behavior. Along with design and technique, alloy characteristics of endodontic instruments is one of the main variables affecting clinical performance. Modification in NiTi alloys is numerous and may yield improvements, but also drawbacks. Martensitic instruments seem to display better cyclic fatigue properties at the expense of surface hardness, prompting the need for surface treatments. On the contrary, such surface treatments may improve cutting efficiency but are detrimental to the gain in cyclic fatigue resistance. Although the design of the instrument is vital, it should in no way cloud the importance of the properties of the alloy and how they influence the clinical behavior of NiTi instruments. Dentists are mostly clinicians rather than engineers. With the advances in instrumentation design and alloys, they have an obligation to deal more intimately with engineering consideration to not only take advantage of their possibilities but also acknowledge their limitations.

Cyclic fatigue resistance of 3 different nickel-titanium reciprocating instruments in artificial canals.

Science.gov (United States)

Higuera, Oscar; Plotino, Gianluca; Tocci, Luigi; Carrillo, Gabriela; Gambarini, Gianluca; Jaramillo, David E

2015-06-01

The purpose of this study was to evaluate the cyclic fatigue resistance of 3 different nickel-titanium reciprocating instruments. A total of 45 nickel-titanium instruments were tested and divided into 3 experimental groups (n = 15): group 1, WaveOne Primary instruments; group 2, Reciproc R25 instruments; and group 3, Twisted File (TF) Adaptive M-L1 instruments. The instruments were then subjected to cyclic fatigue test on a static model consisting of a metal block with a simulated canal with 60° angle of curvature and a 5-mm radius of curvature. WaveOne Primary, Reciproc R25, and TF Adaptive instruments were activated by using their proprietary movements, WaveOne ALL, Reciproc ALL, and TF Adaptive, respectively. All instruments were activated until fracture occurred, and the time to fracture was recorded visually for each file with a 1/100-second chronometer. Mean number of cycles to failure and standard deviations were calculated for each group, and data were statistically analyzed (P fatigue resistance of Reciproc R25 and TF Adaptive M-L1 was significantly higher than that of WaveOne Primary (P = .009 and P = .002, respectively). The results showed no statistically significant difference between TF Adaptive M-L1 and Reciproc R25 (P = .686). Analysis of the fractured portion under scanning electron microscopy indicated that all instruments showed morphologic characteristics of ductile fracture that were due to accumulation of metal fatigue. No statistically significant differences were found between the instruments tested except for WaveOne Primary, which showed the lowest resistance to cyclic fatigue. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Theromdynamics of carbon in nickel-based multicomponent solid solutions

International Nuclear Information System (INIS)

Bradley, D.J.

1978-04-01

The activity coefficient of carbon in nickel, nickel-titanium, nickel-titanium-chromium, nickel-titanium-molybdenum and nickel-titanium-molybdenum-chromium alloys has been measured at 900, 1100 and 1215 0 C. The results indicate that carbon obeys Henry's Law over the range studied (0 to 2 at. percent). The literature for the nickel-carbon and iron-carbon systems are reviewed and corrected. For the activity of carbon in iron as a function of composition, a new relationship based on re-evaluation of the thermodynamics of the CO/CO 2 equilibrium is proposed. Calculations using this relationship reproduce the data to within 2.5 percent, but the accuracy of the calibrating standards used by many investigators to analyze for carbon is at best 5 percent. This explains the lack of agreement between the many precise sets of data. The values of the activity coefficient of carbon in the various solid solutions are used to calculate a set of parameters for the Kohler-Kaufman equation. The calculations indicate that binary interaction energies are not sufficient to describe the thermodynamics of carbon in some of the nickel-based solid solutions. The results of previous workers for carbon in nickel-iron alloys are completely described by inclusion of ternary terms in the Kohler-Kaufman equation. Most of the carbon solid solution at high temperatures in nickel and nickel-titantium alloys precipitates from solution on quenching in water. The precipitate is composed of very small particles (greater than 2.5 nm) of elemental carbon. The results of some preliminary thermomigration experiments are discussed and recommendations for further work are presented

Relative SHG measurements of metal thin films: Gold, silver, aluminum, cobalt, chromium, germanium, nickel, antimony, titanium, titanium nitride, tungsten, zinc, silicon and indium tin oxide

Directory of Open Access Journals (Sweden)

Franklin Che

Full Text Available We have experimentally measured the surface second-harmonic generation (SHG of sputtered gold, silver, aluminum, zinc, tungsten, copper, titanium, cobalt, nickel, chromium, germanium, antimony, titanium nitride, silicon and indium tin oxide thin films. The second-harmonic response was measured in reflection using a 150 fs p-polarized laser pulse at 1561 nm. We present a clear comparison of the SHG intensity of these films relative to each other. Our measured relative intensities compare favorably with the relative intensities of metals with published data. We also report for the first time to our knowledge the surface SHG intensity of tungsten and antimony relative to that of well known metallic thin films such as gold and silver. Keywords: Surface second-harmonic generation, Nonlinear optics, Metal thin films

Fatigue resistance of engine-driven rotary nickel-titanium endodontic instruments.

Science.gov (United States)

Chaves Craveiro de Melo, Marta; Guiomar de Azevedo Bahia, Maria; Lopes Buono, Vicente Tadeu

2002-11-01

A comparative study of the fatigue resistance of engine-driven nickel-titanium endodontic instruments was performed, aiming to access the influence of the cutting flute design and of the size of the files that reach the working length in curved canal shaping. Geometrical conditions similar to those found in practice were used. Series 29 #5 ProFile, together with #6 and #8 Quantec instruments, were tested in artificial canals with a 45-degree angle of curvature and 5-mm radius of curvature. It was observed that the size of the instrument, which determines the maximum strain amplitude during cyclic deformation, is the most important factor controlling fatigue resistance. The effect of heat sterilization on the fatigue resistance of the instruments was also examined. The results obtained indicate that the application of five sterilization procedures in dry heat increases the average number of cycles to failure of unused instruments by approximately 70%.

Cyclic fatigue of nickel-titanium rotary instruments in a double (S-shaped) simulated curvature.

Science.gov (United States)

Al-Sudani, Dina; Grande, Nicola M; Plotino, Gianluca; Pompa, Giorgio; Di Carlo, Stefano; Testarelli, Luca; Gambarini, Gianluca

2012-07-01

The goal of the present study was to test the fatigue resistance of nickel-titanium rotary files in a double curvature (S-shaped) artificial root canal and to compare those results with single curvature artificial root canals. Two nickel-titanium endodontic instruments consisting of identical instrument sizes (constant .06 taper and 0.25 tip diameter) were tested, ProFile instruments and Vortex instruments. Both instruments were tested for fatigue inside an artificial canal with a double curvature and inside a curved artificial canal with a single curvature. Ten instruments for each group were tested to fracture in continuous rotary motion at 300 rpm. Number of cycles to failure (NCF) was calculated to the nearest whole number, and the length of the fractured fragment was measured in millimeters. Data were statistically analyzed with a level of significance set at 95% confidence level. The NCF value was always statistically lower in the double curved artificial canal when compared with the single curve (P instruments of the same size of different brand only in the single curve; ProFile registered a mean of 633.5 ± 75.1 NCF, whereas Vortex registered a mean of 548 ± 48.9 NCF. Regardless of the differences between the instruments used in the present study, the results suggest that the more complex is the root canal, the more adverse are the effects on the cyclic fatigue resistance of the instruments. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Phase equilibria and thermodynamic studies in the titanium-nickel and titanium-nickel-oxygen systems

International Nuclear Information System (INIS)

Chattopadhyay, G.; Kleykamp, H.; Laumer, W.

1983-01-01

The isothermal section of the Ti-Ni-O system was examined at 1200 K in the regions between the Ni(Ti) solid solution and the binary oxides of titanium. The relative partial Gibbs energies of oxygen over the Ti 2 O 3 -Ti 3 O 5 region and of titanium in the Ni(Ti) solid solution as well as the Gibbs energies of formation of NiTiO 3 , Ti 3 O 5 and TiNi 3 were determined between 1100 and 1300 K by use of solid electrolyte galvanic cells. (orig.) [de

Comparison of the mechanical properties between tantalum and nickel-titanium foams implant materials for bone ingrowth applications

International Nuclear Information System (INIS)

Sevilla, P.; Aparicio, C.; Planell, J.A.; Gil, F.J.

2007-01-01

Metallic porous materials are designed to allow the ingrowth of living tissue inside the pores and to improve the mechanical anchorage of the implant. In the present work, tantalum and nickel-titanium porous materials have been characterized. The tantalum foams were produced by vapour chemical deposition (CVD/CVI) and the NiTi foams by self-propagating high temperature synthesis (SHS). The former exhibited an open porosity ranging between 65 and 73% and for the latter it ranged between 63 and 68%. The pore sizes were between 370 and 440 μm for tantalum and between 350 and 370 μm for nickel-titanium. The Young's modulus in compression of the foams studied, especially for tantalum, were very similar to those of cancellous bone. This similitude may be relevant in order to minimize the stress shielding effect in the load transfer from the implant to bone. The strength values for NiTi foam are higher than for tantalum, especially of the strain to fracture which is about 23% for NiTi and only 8% for tantalum. The fatigue endurance limit set at 10 8 cycles is about 7.5 MPa for NiTi and 13.2 MPa for tantalum. The failure mechanisms have been studied by scanning electron microscopy

Stress Relaxation Of Superelastic Shape Memory Alloy Under Bending And Torsional Load

Directory of Open Access Journals (Sweden)

Sakib Tanvir

2017-04-01

Full Text Available Stress Relaxation of Superelastic Shape memory NiTi Alloy under bending and torsion is uncommon in literature. Therefore experimental set up has been devised and test results are obtained for superelastic SMA.Unlike the other common engineering materials superelastic SMA it gives dramatic reduction in stress. In this paper therefore results of stress relaxation of superelastic shape memory alloy under bending and torsion are presented graphically and interpreted in terms of stress induced martensitic transformation.

Radius scaling of titanium wire arrays on the Z accelerator

International Nuclear Information System (INIS)

Coverdale, C.A.; Denney, C.; Spielman, R.B.

1999-01-01

The 20 MA Z accelerator has made possible the generation of substantial radiation (> 100 kJ) at higher photon energies (4.8 keV) through the use of titanium wire arrays. In this paper, the results of experiments designed to study the effects of initial load radius variations of nickel-clad titanium wire arrays will be presented. The load radius was varied from 17.5 mm to 25 mm and titanium K-shell (4.8 keV) yields of greater than 100 kJ were measured. The inclusion of the nickel cladding on the titanium wires allows for higher wire number loads and increases the spectral broadness of the source; kilovolt emissions (nickel plus titanium L-shell) of 400 kJ were measured in these experiments. Comparisons of the data to calculations will be made to estimate pinched plasma parameters such as temperature and participating mass fraction. These results will also be compared with previous pure titanium wire array results

Canal preparation with nickel-titanium or stainless steel instruments without the risk of instrument fracture: preliminary observations

OpenAIRE

Ghassan Yared

2015-01-01

This report introduces a novel technique that allows a safe and predictable canal negotiation, creation of a glide path and canal preparation with reciprocating nickel-titanium or stainless steel engine-driven instruments in canals where the use of rotary and the newly developed reciprocating instruments is contraindicated. In this novel technique, the instruments are used in reciprocating motion with very small angles. Hand files are not used regardless of the complexity of the canal anatomy...

Understanding the shape-memory alloys used in orthodontics.

Science.gov (United States)

Fernandes, Daniel J; Peres, Rafael V; Mendes, Alvaro M; Elias, Carlos N

2011-01-01

Nickel-titanium (NiTi) shape-memory alloys (SMAs) have been used in the manufacture of orthodontic wires due to their shape memory properties, super-elasticity, high ductility, and resistance to corrosion. SMAs have greater strength and lower modulus of elasticity when compared with stainless steel alloys. The pseudoelastic behavior of NiTi wires means that on unloading they return to their original shape by delivering light continuous forces over a wider range of deformation which is claimed to allow dental displacements. The aim of this paper is to discuss the physical, metallurgical, and mechanical properties of NiTi used in Orthodontics in order to analyze the shape memory properties, super-elasticity, and thermomechanical characteristics of SMA.

Corrosion of chromium, nickel, titanium and steels in solutions of sodium and ammonium thiosulfates

International Nuclear Information System (INIS)

Grebenshchikova, S.V.; Kochergin, V.P.; Doronina, I.V.

1983-01-01

Results of gravimetric determinatiion of average rate of chromium, nickel, titatnium and steels 12Kh18N10T and VSt.3 corrosion rate in solutions 50 mass.% (NH 4 ) 2 S 2 O 3 and Na 2 S 2 O 3 in the air and nitrogen atmosphere at 333 K have been generalized. Anodic polarization curves are recorded and stationary potentials of metals and steels under the conditions are measured. It is shown that in (NH 4 ) 2 S 2 O 3 solution the rate of metal and steels corrosion is higher than in Na 2 S 2 O 3 solution indepenent of the nature of gaseous medium contacting with solution. In the series Ni → VSt.3 → 12Kh18N10T → VT1 → chromium in (NH 4 ) 2 S 2 O 3 and Na 2 S 2 O 3 solutions at 333 K corrosion resistance increases. Chromium, titanium and chromium-nickel steel 12Kh18N10T possess a high corrosion resistance

Efficacy of Different Nickel-Titanium Instruments in Removing Gutta-percha during Root Canal Retreatment.

Science.gov (United States)

Özyürek, Taha; Demiryürek, Ebru Özsezer

2016-04-01

The aim of this study was to compare the cleanliness of root canal walls after retreatment using ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland), Twisted File Adaptive (TFA; Axis/SybronEndo, Orange, CA), Reciproc (PRC; VDW, Munich, Germany), and ProTaper Universal retreatment (PTR, Dentsply Maillefer) nickel-titanium systems and the time required for gutta-percha and sealer removal. Eighty human maxillary central incisors with single and straight root canals were instrumented up to #40.02 with manual K-files (Dentsply Maillefer) and obturated using the continuous wave of condensation technique. Removal of the gutta-percha and sealer was performed using 1 of the following nickel-titanium systems: PTN, TFA, RPC, or PTR. The teeth were sectioned, and digital images were captured. The photographs were analyzed using AutoCAD software (Autodesk, San Rafael, CA). Also, the total time required for gutta-percha removal was calculated by a chronometer. The total retreatment time was significantly shorter in the PTR group compared with the other groups (P < .05). There was a significant difference between the groups according to the total residual gutta-percha and sealer (P < .05). The PTN and PTR groups left significantly less gutta-percha and sealer remnant than the TFA and RPC groups (P < .05). Within the limitations of this study, the PTN and the PTR groups showed less residual gutta-percha and sealer than the TFA and RPC groups. The time required for gutta-percha and sealer removal was similar for all the groups, except for the PTR group. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Shaping ability of NT Engine and McXim rotary nickel-titanium instruments in simulated root canals. Part 2.

Science.gov (United States)

Thompson, S A; Dummer, P M

1997-07-01

The aim of this laboratory-based study was to determine the shaping ability of NT Engine and McXim nickel-titanium rotary instruments in simulated root canals. A total of 40 canals with four different shapes in terms of angle and position of curve were prepared with NT Engine and McXim instruments, using the technique recommended by the manufacturer. Part 2 of this report describes the efficacy of the instruments in terms of prevalence of canal aberrations, the amount and direction of canal transportation and overall postoperative shape. Pre- and postoperative images of the canals were taken using a video camera attached to a computer with image analysis software. The pre- and postoperative views were superimposed to highlight the amount and position of material removed during preparation. No zips, elbows, perforations or danger zones were created during preparation. Forty-two per cent of canals had ledges on the outer aspect of the curve, the majority of which (16 out of 17) occurred in canals with short acute curves. There were significant differences (P Engine and McXim rotary nickel-titanium instruments created no aberrations other than ledges and produced only minimal transportation. The overall shape of canals was good.

Lateral and axial cutting efficiency of instruments manufactured with conventional nickel-titanium and novel gold metallurgy.

Science.gov (United States)

Vasconcelos, R A; Arias, A; Peters, O A

2018-05-01

To isolate the effect of metallurgy in lateral and axial cutting efficacy against plastic and bovine dentine substrates by comparing two rotary systems with identical design but manufactured with either conventional nickel-titanium or heat-treated gold alloy. A total of 258 ProTaper Universal (PTU) and ProTaper Gold (PTG) Shaping instruments were used. Bending behaviour was assessed to determine the appropriate displacement associated with a 2 N force in lateral cutting. Ten instruments of each type were used in lateral action for 60 s against bovine dentine or plastic substrates four consecutive times producing four notches in each specimen. Ten further instruments of each type were used in on axial action in four standardized simulated root canals fabricated from 4-mm thick plastic or dentine discs. Both tests were performed at 300 rpm in a computer-controlled testing platform. Notch area and torsional load were compared with Student's t-tests. Repeated measures ANOVA was used to compare cutting efficiency across the four different time-points. Pearson correlation coefficients between substrates were also determined. For lateral action, all three PTG instruments cut significantly more effectively (P cut significantly more after 120 and 180 s (P cutting at 180 s on plastic and 120 s on bovine dentine (P cutting efficiency when compared to those made from conventional nickel-titanium. © 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Rapid in situ growth of oriented titanium-nickel oxide composite nanotubes arrays coated on a nitinol wire as a solid-phase microextraction fiber coupled to HPLC-UV.

Science.gov (United States)

Zhen, Qi; Zhang, Min; Song, Wenlan; Wang, Huiju; Wang, Xuemei; Du, Xinzhen

2016-10-01

An oriented titanium-nickel oxide composite nanotubes coating was in situ grown on a nitinol wire by direct electrochemical anodization in ethylene glycol with ammonium fluoride and water for the first time. The morphology and composition of the resulting coating showed that the anodized nitinol wire provided a titania-rich coating. The titanium-nickel oxide composite nanotubes coated fiber was used for solid-phase microextraction of different aromatic compounds coupled to high-performance liquid chromatography with UV detection. The titanium-nickel oxide composite nanotubes coating exhibited high extraction capability, good selectivity, and rapid mass transfer for weakly polar UV filters. Thereafter the important parameters affecting extraction efficiency were investigated for solid-phase microextraction of UV filters. Under the optimized conditions, the calibration curves were linear in the range of 0.1-300 μg/L for target UV filters with limits of detection of 0.019-0.082 μg/L. The intraday and interday precision of the proposed method with the single fiber were 5.3-7.2 and 5.9-7.9%, respectively, and the fiber-to-fiber reproducibility ranged from 6.3 to 8.9% for four fibers fabricated in different batches. Finally, its applicability was evaluated by the extraction and determination of target UV filters in environmental water samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Use of nickel titanium closed-coil springs to align unerupted teeth: a case report.

Science.gov (United States)

Samuels, R H; Peak, J D

1998-03-01

We describe a case in which a patient with a class II division I incisor relationship on a skeletal II base was transferred midway through a treatment that consisted of aligning the upper and lower arches with fixed appliance orthodontics in preparation for a mandibular advancement osteotomy. The lower second molars had previously been extracted; the lower third molars were left unerupted and some distance from the lower first molars. To provide a good occlusion at the end of treatment, it was decided to expose and approximate the lower third molars to the distal aspect of the lower first molars with the use of nickel titanium closed-coil springs; this was to be done before the osteotomy.

Comparison of cyclic fatigue resistance of novel nickel-titanium rotary instruments.

Science.gov (United States)

Capar, Ismail Davut; Ertas, Huseyin; Arslan, Hakan

2015-04-01

New files (ProTaper Next/HyFlex/OneShape) are made from novel nickel-titanium (NiTi) alloys/treatments. The purpose of this study was to compare the cyclic fatigue resistance of these new instruments with that of Revo-S instruments. Four groups of 20 NiTi endodontic instruments were tested in steel canals with a 3 mm radius and a 60° angle of curvature. The cyclic fatigue of the following NiTi instruments with a tip size 25 and 0.06 taper that were manufactured with different alloys was tested: ProTaper Next X2 (M-Wire), OneShape (conventional NiTi), Revo-S Shaping Universal (conventional NiTi) and HyFlex 25/0.6 (controlled memory NiTi wire). A one-way anova and post-hoc Tukey's test (α = 0.05) revealed that the HyFlex files had the highest fatigue resistance and the Revo-S had the least fatigue resistance among the groups (P < 0.001). © 2014 Australian Society of Endodontology.

Friction behavior and other material properties of nickel-titanium and titanium-molybdenum archwires following electrochemical surface refinement.

Science.gov (United States)

Meier, Miriam Julia; Bourauel, Christoph; Roehlike, Jan; Reimann, Susanne; Keilig, Ludger; Braumann, Bert

2014-07-01

The aim of this work was to investigate whether electrochemical surface treatment of nickel-titanium (NiTi) and titanium-molybdenum (TiMo) archwires (OptoTherm and BetaTitan; Ortho-Dent Specials, Kisdorf, Germany) reduces friction inside the bracket-archwire complex. We also evaluated further material properties and compared these to untreated wires. The material properties of the surface-treated wires (Optotherm/LoFrix and BetaTitan/LoFrix) were compared to untreated wires made by the same manufacturer (see above) and by another manufacturer (Neo Sentalloy; GAC, Bohemia, NY, USA). We carried out a three-point bending test, leveling test, and friction test using an orthodontic measurement and simulation system (OMSS). In addition, a pure bending test was conducted at a special test station, and scanning electron micrographs were obtained to analyze the various wire types for surface characteristics. Finally, edge beveling and cross-sectional dimensions were assessed. Force losses due to friction were reduced by 10 percentage points (from 36 to 26%) in the NiTi and by 12 percentage points (from 59 to 47%) in the TiMo wire specimens. Most of the other material properties exhibited no significant changes after surface treatment. While the three-point bending tests revealed mildly reduced force levels in the TiMo specimens due to diameter losses of roughly 2%, these force levels remained almost unchanged in the NiTi specimens. Compared to untreated NiTi and TiMo archwire specimens, the surface-treated specimens demonstrated reductions in friction loss by 10 and 12 percentage points, respectively.

Electroplating on titanium alloy

Science.gov (United States)

Lowery, J. R.

1971-01-01

Activation process forms adherent electrodeposits of copper, nickel, and chromium on titanium alloy. Good adhesion of electroplated deposits is obtained by using acetic-hydrofluoric acid anodic activation process.

Microstructures and martensitic transformation behavior of superelastic Ti-Ni-Ag scaffolds

Energy Technology Data Exchange (ETDEWEB)

Li, Shuanglei; Kim, Eun-soo [School of Materials Science and Engineering & ERI, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of); Kim, Yeon-wook [Department of Material Engineering, Keimyung University, 1000 Shindang-dong, Dalseo-gu, Daegu 704-701 (Korea, Republic of); Nam, Tae-hyun, E-mail: tahynam@gnu.ac.kr [School of Materials Science and Engineering & ERI, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of)

2016-10-15

Highlights: • The B2-R-B19′ transformation occurred in 49Ti-50.3Ni-0.7Ag alloy fibers. • Annealing treated alloy fibers showed superelastic recovery ratio of 93%. • Ageing treated scaffold had an elastic modulus of 0.67 GPa. • Ageing treated scaffold exhibited good superelasticity at human body temperature. - Abstract: Ti-Ni-Ag scaffolds were prepared by sintering rapidly solidified alloy fibers. Microstructures and transformation behaviors of alloy fibers and scaffolds were investigated by means of electron probe micro-analyzer (EPMA), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The B2-R-B19′ transformation occurs in alloy fibers. The alloy fibers have good superelasticity with superelastic recovery ratio of 93% after annealing heat treatment. The as-sintered Ti-Ni-Ag scaffolds possess three-dimensional and interconnected pores and have the porosity level of 80%. The heat treated Ti-Ni-Ag scaffolds not only have an elastic modulus of 0.67 GPa, which match well with that of cancellous bone, but also show excellent superelasticity at human body temperature. In terms of the mechanical properties, the Ti-Ni-Ag scaffolds in this study can meet the main requirements of bone scaffold for the purpose of bone replacement applications.

Effect of nitrogen addition on superelasticity of Ti-Zr-Nb alloys

International Nuclear Information System (INIS)

Tahara, Masaki; Kim, Hee Young; Miyazaki, Shuichi; Inamura, Tomonari; Hosoda, Hideki

2008-01-01

Recently, the Ti-Zr-Nb alloys have been developed as Ni-free shape memory and superelastic alloys. In this study, the effect of Nb and nitrogen (N) contents on martensitic transformation behavior, shape memory effect and superelasticity in Ti-18Zr-(12-16)Nb-(0-1.0)N (at%) alloys were investigated using tensile tests, optical microscopy and X-ray diffraction. Shape memory effect was observed in Ti-18Zr-(12-13)Nb and Ti-18Zr-12Nb-0.5N alloys at room temperature. The superelastic behavior appeared by the increase of Nb or N content. The Ti-18Zr-(14-15)Nb, Ti-18Zr-(13-14)Nb-0.5N and Ti-18Zr-(12-14)Nb-1.0N alloys exhibited the superelasticity at room temperature. The martensitic transformation start temperature (M s ) decreased by 75 K with 1 at% increase of N content for Ti-18Zr-13Nb alloy. The critical stress for slip deformation and the stress for inducing the martensitic transformation increased with increasing N content. The superelastic recovery strain was also increased by adding N. The maximum recovery strain of 5.0% was obtained in the Ti-18Zr-14Nb-0.5N alloy. (author)

A Constitutive Model for Superelastic Shape Memory Alloys Considering the Influence of Strain Rate

Directory of Open Access Journals (Sweden)

Hui Qian

2013-01-01

Full Text Available Shape memory alloys (SMAs are a relatively new class of functional materials, exhibiting special thermomechanical behaviors, such as shape memory effect and superelasticity, which enable their applications in seismic engineering as energy dissipation devices. This paper investigates the properties of superelastic NiTi shape memory alloys, emphasizing the influence of strain rate on superelastic behavior under various strain amplitudes by cyclic tensile tests. A novel constitutive equation based on Graesser and Cozzarelli’s model is proposed to describe the strain-rate-dependent hysteretic behavior of superelastic SMAs at different strain levels. A stress variable including the influence of strain rate is introduced into Graesser and Cozzarelli’s model. To verify the effectiveness of the proposed constitutive equation, experiments on superelastic NiTi wires with different strain rates and strain levels are conducted. Numerical simulation results based on the proposed constitutive equation and experimental results are in good agreement. The findings in this paper will assist the future design of superelastic SMA-based energy dissipation devices for seismic protection of structures.

Comparison of changes in irregularity and transverse width with nickel-titanium and niobium-titanium-tantalum-zirconium archwires during initial orthodontic alignment in adolescents: A double-blind randomized clinical trial.

Science.gov (United States)

Nordstrom, Barrett; Shoji, Toshihiro; Anderson, W Cameron; Fields, Henry W; Beck, F Michael; Kim, Do-Gyoon; Takano-Yamamoto, Teruko; Deguchi, Toru

2018-05-01

The purpose of this prospective, double-blind, randomized clinical trial was to compare the clinical efficiency of nickel-titanium (NiTi) and niobium-titanium-tantalum-zirconium (TiNbTaZr) archwires during initial orthodontic alignment. All subjects (ages between 12 and 20 years) underwent nonextraction treatment using 0.022-inch brackets. All patients were randomized into two groups for initial alignment with 0.016-inch NiTi archwires (n = 14), or with 0.016-inch TiNbTaZr archwires (n = 14). Digital scans were taken during the course of treatment and were used to compare the improvement in Little's Irregularity Index and the changes in intercanine and intermolar widths. There was approximately a 27% reduction in crowding during the first month with the use of 0.016-inch TiNbTaZr (Gummetal) wire, and an additional 25% decrease in crowding was observed during the next month. There was no significant difference between the two treatment groups in the decrease in irregularity over time ( P = .29). There was no significant difference between the two groups in the changes in intercanine and intermolar width ( P = .80). It can be concluded that Gummetal wires and conventional NiTi wires possess a similar ability to align teeth, and Gummetal wires have additional advantages over conventional NiTi, such as formability and use in patients with nickel allergy.

A Survey on Nickel Titanium Rotary Instruments and their Usage Techniques by Endodontists in India.

Science.gov (United States)

Patil, Thimmanagowda N; Saraf, Prahlad A; Penukonda, Raghavendra; Vanaki, Sneha S; Kamatagi, Laxmikant

2017-05-01

The preference and usage of nickel titanium rotary instruments varies from individual to individual based on their technique, experience with the rotary systems and the clinical situation. Very limited information is available to explain the adoption of changing concepts with respect to nickel titanium rotary instruments pertaining to the endodontists in India. The aim of this study was to conduct a questionnaire survey to acquire the knowledge concerning different NiTi rotary instruments and their usage techniques by endodontists in India. A Survey questionnaire was designed which consisted of 32 questions regarding designation, demographics, experience with rotary instruments, usage of different file systems, usage techniques, frequency of reuse, occurrence of file fracture, reasons and their management was distributed by hand in the national postgraduate convention and also disseminated via electronic medium to 400 and 600 endodontists respectively. Information was collected from each individual to gain insight into the experiences and beliefs of endodontists concerning the new endodontic technology of rotary NiTi instrumentation based on their clinical experience with the rotary systems. The questions were designed to ascertain the problems, patterns of use and to identify areas of perceived or potential concern regarding the rotary instruments and the data acquired was statistically evaluated using Fisher's-exact test and the Chi-Square test. Overall 63.8% (638) endodontists responded. ProTaper was one of the most commonly used file system followed by M two and ProTaper Next. There was a significant co relation between the years of experience and the file re use frequency, preparation technique, file separation, management of file separation. A large number of Endodontists prefer to reuse the rotary NiTi instruments. As there was an increase in the experience, the incidence of file separation reduced with increasing number of re use frequency and with

Effect of ion-implantation on surface characteristics of nickel titanium and titanium molybdenum alloy arch wires

Directory of Open Access Journals (Sweden)

Manu Krishnan

2013-01-01

Full Text Available Aim: To evaluate the changes in surface roughness and frictional features of ′ion-implanted nickel titanium (NiTi and titanium molybdenum alloy (TMA arch wires′ from its conventional types in an in-vitro laboratory set up. Materials and Methods: ′Ion-implanted NiTi and low friction TMA arch wires′ were assessed for surface roughness with scanning electron microscopy (SEM and 3 dimensional (3D optical profilometry. Frictional forces were studied in a universal testing machine. Surface roughness of arch wires were determined as Root Mean Square (RMS values in nanometers and Frictional Forces (FF in grams. Statistical Analysis Used: Mean values of RMS and FF were compared by Student′s ′t′ test and one way analysis of variance (ANOVA. Results: SEM images showed a smooth topography for ion-implanted versions. 3D optical profilometry demonstrated reduction of RMS values by 58.43% for ion-implanted NiTi (795.95 to 330.87 nm and 48.90% for TMA groups (463.28 to 236.35 nm from controls. Nonetheless, the corresponding decrease in FF was only 29.18% for NiTi and 22.04% for TMA, suggesting partial correction of surface roughness and disproportionate reduction in frictional forces with ion-implantation. Though the reductions were highly significant at P < 0.001, relations between surface roughness and frictional forces remained non conclusive even after ion-implantation. Conclusion: The study proved that ion-implantation can significantly reduce the surface roughness of NiTi and TMA wires but could not make a similar reduction in frictional forces. This can be attributed to the inherent differences in stiffness and surface reactivity of NiTi and TMA wires when used in combination with stainless steel brackets, which needs further investigations.

The placement of Y-shaped titanium-nickel memory alloy stent in the carina: a fundamental study in experimental canines

International Nuclear Information System (INIS)

Bian Wei; Shen Che

2010-01-01

Objective: To investigate the pathological changes of local airway tissue after inserting Yshaped titanium-nickel memory alloy stent in carina, and to evaluate CT three-dimensional reconstruction technique in postoperative and follow-up observation. Methods: Twelve healthy adult canines were enrolled in this study. Based on the information of the carina obtained from CT three-dimensional reconstruction images, the preparation of Y-shape netlike stent was made by knitting method with single Ni-Ti memory alloy wire. The stent was then inserted in canine's carina with the help of a releasing system. After the operation fiberbronchoscopy and CT three-dimensional reconstruction were performed. The animals were sacrificed 12 weeks after the procedure and the bronchus of the stenting segment was removed and sent for histopathologic examination. Results: Technical success was achieved in all canines with the stent right in the carina. The airway remained unobstructed 12 weeks after the procedure. Histopathologic examination revealed that the stent became partial epithelialization. Conclusion: The Y-shaped titanium-nickel memory alloy stent has good histocompatibility and physicochemical stability and no re-stenosis of the airway develops in the follow-up period of three months. The stent-releasing technique is easy and simple. As a non-invasive and convenient exam, CT three-dimensional reconstruction technique is of great value in postoperative follow-up observation. (authors)

Mechanical response of nickel-titanium instruments with different cross-sectional designs during shaping of simulated curved canals.

Science.gov (United States)

Kim, H C; Kim, H J; Lee, C J; Kim, B M; Park, J K; Versluis, A

2009-07-01

To evaluate how different cross-sectional designs affect stress distribution in nickel-titanium (NiTi) instruments during bending, torsion and simulated shaping of a curved canal. Four NiTi rotary instruments with different cross-sectional geometries were selected: ProFile and HeroShaper systems with a common triangle-based cross section, Mtwo with an S-shaped rectangle-based design and NRT with a modified rectangle-based design. The geometries of the selected files were scanned in a micro-CT and three-dimensional finite-element models were created for each system. Stiffness characteristics for each file system were determined in a series of bending and torsional conditions. Canal shaping was simulated by inserting models of the rotating file into a 45 degrees curved canal model. Stress distribution in the instruments was recorded during simulated shaping. After the instruments were retracted from the canal, residual stresses and permanent bending of their tips due to plastic deformation were determined. The greatest bending and torsional stiffness occurred in the NRT file. During simulated shaping, the instruments with triangle-based cross-sectional geometry had more even stress distributions along their length and had lower stress concentrations than the instruments with rectangle-based cross sections. Higher residual stresses and plastic deformations were found in the Mtwo and NRT with rectangle-based cross-sectional geometries. Nickel-titanium instruments with rectangle-based cross-sectional designs created higher stress differentials during simulated canal shaping and may encounter higher residual stress and plastic deformation than instruments with triangle-based cross sections.

Synthesis of cerium and nickel doped titanium nanofibers for hydrolysis of sodium borohydride.

Science.gov (United States)

Tamboli, Ashif H; Gosavi, S W; Terashima, Chiaki; Fujishima, Akira; Pawar, Atul A; Kim, Hern

2018-07-01

A recyclable titanium nanofibers, doped with cerium and nickel doped was successfully synthesized by using sol-gel and electrospinning method for hydrogen generation from alkali free hydrolysis of NaBH 4 . The resultant nanocomposite was characterized to find out the structural and physical-chemical properties by a series of analytical techniques such as FT-IR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), SEM (scanning electron microscope), EDX (energy-dispersive X-ray spectroscopy),N 2 adsorption-desorption and BET (Brunauer-Emmett-Teller), etc. The results revealed that cerium and nickel nanoparticles were homogeneously distributed on the surface of the TiO 2 nanofibers due to having similar oxidation state and atomic radium of TiO 2 nanofibers with CeO 2 and NiO for the effective immobilization of metal ions. The NiO doped catalyst showed superior catalytic performance towards the hydrolysis reaction of NaBH 4 at room temperature. These catalysts have ability to produce 305 mL of H 2 within the time of 160 min at room temperature. Additionally, reusability test revealed that the catalyst is active even after five runs of hydrolytic reaction, implying the as-prepared NiO doped TiO 2 nanofibers could be considered as a potential candidate catalyst for portable hydrogen fuel system such as PEMFC (proton exchange membrane fuel cells). Copyright © 2018 Elsevier Ltd. All rights reserved.

Nickel-titanium wire as a flexor tendon suture material: an ex vivo study.

Science.gov (United States)

Karjalainen, T; Göransson, H; Viinikainen, A; Jämsä, T; Ryhänen, J

2010-07-01

Nickel-titanium shape memory alloy (NiTi) is a new suture material that is easy to handle, is strong, and biocompatible. The purpose of this study was to evaluate the material properties and biomechanical behaviour of 150 microm and 200 microm NiTi wires in flexor tendon repair. Braided polyester (4-0 Ethibond) was used as control. Fifty fresh-frozen porcine flexor tendons were repaired using the Pennington modification of the Kessler repair or a double Kessler technique. NiTi wires were stiffer and reached higher tensile strength compared to braided polyester suture. Repairs with 200 microm NiTi wire had a higher yield force, ultimate force and better resistance to gapping than 4-0 braided polyester repairs. Repairs made with 200 microm NiTi wire achieved higher stiffness and ultimate force than repairs made with 150 microm NiTi wire.

Nickel-Titanium Alloys: Corrosion "Proof" Alloys for Space Bearing, Components and Mechanism Applications

Science.gov (United States)

DellaCorte, Christopher

2010-01-01

An intermetallic nickel-titanium alloy, 60NiTi (60 wt% Ni, 40 wt% Ti), is shown to be a promising candidate tribological material for space mechanisms. 60NiTi offers a broad combination of physical properties that make it unique among bearing materials. 60NiTi is hard, electrically conductive, highly corrosion resistant, readily machined prior to final heat treatment, and is non-magnetic. Despite its high Ti content, 60NiTi is non-galling even under dry sliding. No other bearing alloy, metallic or ceramic, encompasses all of these attributes. Since 60NiTi contains such a high proportion of Ti and possesses many metallic properties, it was expected to exhibit poor tribological performance typical of Ti alloys, namely galling type behavior and rapid lubricant degradation. In this poster-paper, the oil-lubricated behavior of 60NiTi is presented.

Behavior of nickel-titanium instruments manufactured with different thermal treatments.

Science.gov (United States)

Pereira, Érika Sales Joviano; Viana, Ana Cecília Diniz; Buono, Vicente Tadeu Lopes; Peters, Ove A; Bahia, Maria Guiomar de Azevedo

2015-01-01

The purpose of this study was to investigate if nickel-titanium instruments with similar designs manufactured by different thermal treatments would exhibit significantly different in vitro behavior. Thirty-six instruments each of ProTaper Universal (PTU F1; Dentsply Maillefer, Ballaigues, Switzerland), ProFile Vortex (PV; Dentsply Tulsa Dental Specialties, Tulsa, OK), Vortex Blue (VB, Dentsply Tulsa Dental Specialties), and TYPHOON Infinite Flex NiTi (TYP; Clinician's Choice Dental Products, New Milford, CT) (all size 25/.06) were evaluated. Bending resistance, torsion at failure, and dynamic torsional tests were performed with the instruments (n = 12). Analysis of variance and Tukey post hoc tests were applied. Flexibility was significantly higher for TYP compared with the other 3 groups (P .05). The highest mean forces were recorded with PTU (7.02 ± 2.36 N) and the lowest with TYP (1.22 ± 0.40 N). TYP instruments were significantly more flexible than the other instruments tested. The PV group had the highest torsional strength and TYP, despite being the most flexible, showed similar torsional moments to the other instruments, whereas its angular deflection was the highest among the groups. Copyright © 2015 American Association of Endodontists. All rights reserved.

Canal preparation with nickel-titanium or stainless steel instruments without the risk of instrument fracture: preliminary observations

Directory of Open Access Journals (Sweden)

Ghassan Yared

2015-02-01

Full Text Available This report introduces a novel technique that allows a safe and predictable canal negotiation, creation of a glide path and canal preparation with reciprocating nickel-titanium or stainless steel engine-driven instruments in canals where the use of rotary and the newly developed reciprocating instruments is contraindicated. In this novel technique, the instruments are used in reciprocating motion with very small angles. Hand files are not used regardless of the complexity of the canal anatomy. It also allows achieving predictable results in canal negotiation and glide path creation in challenging canals without the risk of instrument fracture.

Stochastic seismic response of building with super-elastic damper

Science.gov (United States)

Gur, Sourav; Mishra, Sudib Kumar; Roy, Koushik

2016-05-01

Hysteretic yield dampers are widely employed for seismic vibration control of buildings. An improved version of such damper has been proposed recently by exploiting the superelastic force-deformation characteristics of the Shape-Memory-Alloy (SMA). Although a number of studies have illustrated the performance of such damper, precise estimate of the optimal parameters and performances, along with the comparison with the conventional yield damper is lacking. Presently, the optimal parameters for the superelastic damper are proposed by conducting systematic design optimization, in which, the stochastic response serves as the objective function, evaluated through nonlinear random vibration analysis. These optimal parameters can be employed to establish an initial design for the SMA-damper. Further, a comparison among the optimal responses is also presented in order to assess the improvement that can be achieved by the superelastic damper over the yield damper. The consistency of the improvements is also checked by considering the anticipated variation in the system parameters as well as seismic loading condition. In spite of the improved performance of super-elastic damper, the available variant of SMA(s) is quite expensive to limit their applicability. However, recently developed ferrous SMA are expected to offer even superior performance along with improved cost effectiveness, that can be studied through a life cycle cost analysis in future work.

[Shaping ability of multi-taper nickel-titanium files in simulated resin curved root canal].

Science.gov (United States)

Luo, Hong-Xia; Huang, Ding-Ming; Jia, Liu-He; Luo, Shi-Gao; Gao, Xiao-Jie; Tan, Hong; Zhou, Xue-Dong

2006-08-01

To compare the shaping ability of ISO standard stainless steel K files and multi-taper ProTaper nickel-titanium files in simulated resin curved root canals. METHODS Thirty simulated resin root canals were randomly divided into three groups and prepared by stainless steel K files, hand ProTaper, rotary ProTaper, respectively. The amount of material removed from inner and outer wall and canal width after canal preparation was measured, while the canal curvature before and after canal preparation and canals aberrations were recorded. The stainless steel K files removed more material than hand ProTaper and rotary ProTaper at the outer side of apex and inner side of curvature (P ProTaper group (P ProTaper had no evident aberration. The shaping ability of ProTaper is better than stainless steel K files.

Corrosion of titanium and titanium alloys in spent fuel repository conditions - literature review

International Nuclear Information System (INIS)

Aho-Mantila, I.; Haenninen, H.; Aaltonen, P.; Taehtinen, S.

1985-03-01

The spent nuclear fuel is planned to be disposed in Finnish bedrock. The canister of spent fuel in waste repository is one barrier to the release of radionuclides. It is possible to choose a canister material with a known, measurable corrosion rate and to make it with thickness allowing corrosion to occur. The other possibility is to use a material which is nearly immune to general corrosion. In this second category there are titanium and titanium alloys which exhibit a very high degree of resistance to general corrosion. In this literature study the corrosion properties of unalloyed titanium, titanium alloyed with palladium and titanium alloyed with molybdenum and nickel are reviewed. The two titanium alloys own in addition to the excellent general corrosion properties outstanding properties against localized corrosion like pitting or crevice corrosion. Stress corrosion cracking and corrosion fatique of titanium seem not to be a problem in the repository conditions, but the possibilities of delayed cracking caused by hydrogen should be carefully appreciated. (author)

New excitation functions for proton induced reactions on natural titanium, nickel and copper up to 70 MeV

Energy Technology Data Exchange (ETDEWEB)

Garrido, E. [SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS/IN2P3, Nantes (France); Duchemin, C., E-mail: Charlotte.Duchemin@subatech.in2p3.fr [SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS/IN2P3, Nantes (France); Guertin, A. [SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS/IN2P3, Nantes (France); Haddad, F.; Michel, N. [SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS/IN2P3, Nantes (France); GIP Arronax, 1 rue Aronnax, 44817 Saint-Herblain (France); Métivier, V. [SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS/IN2P3, Nantes (France)

2016-09-15

Highlights: • Natural titanium, nickel and copper targets. • 70 MeV ARRONAX cyclotron proton beam. • Stacked-foil technique and monitor reactions. • Experimental cross section values. • TALYS code version 1.6. - Abstract: New excitation functions for proton induced nuclear reactions on natural titanium, nickel and copper were measured, using the stacked-foil technique and gamma spectrometry, up to 70 MeV. The experimental cross sections were measured using the Ti-nat(p,x) V-48, Ni-nat(p,x) Ni-57 and Cu-nat(p,x) Zn-62,Co-56 monitor reactions recommended by the International Atomic Energy Agency (IAEA), depending on the investigated energy range. Data have been extracted for the Ti-nat(p,x) Sc-43,44m,46,47,48, V-48, K-42,43, Ni-nat(p,x) Ni-56,57, Co-55,56,57,58, Mn-52,54, Cu-nat(p,x) Cu-61,64, Ni-57, Co-56,57,58,60, Zn-62,65, Mn-54 reactions. Our results are discussed and compared to the existing ones as well as with the TALYS code version 1.6 calculations using default models. Our experimental data are in overall good agreement with the literature. TALYS is able to reproduce, in most cases, the experimental trend. Our new experimental results allow to expand our knowledge on these excitation functions, to confirm the existing trends and to give additional values on a large energy range. This work is in line with the new Coordinated Research Project (CRP) launched by the IAEA to expand the database of monitor reactions.

Mechanical characterisation of orthodontic superelastic Ni-Ti wires

Energy Technology Data Exchange (ETDEWEB)

Arrigoni, M.; Pietrabissa, R. [Politecnico di Milano, Milano (Italy). Lab. of Biological Structure Mechanics; Auricchio, F.; Petrini, L. [Politecnico di Milano, Milano (Italy). Lab. of Biological Structure Mechanics; Pavia Univ. (Italy). Dept. of Structural Mechanics; Cacciafesta, V. [Politecnico di Milano, Milano (Italy). Lab. of Biological Structure Mechanics; Pavia Univ. (Italy). Dept. of Orthodontia

2001-11-01

Nowadays, the orthodontic treatment is improving thanks to the introduction of Ni-Ti super-elastic alloy wires in the ordinary therapy. Indeed, laboratory tests performed in the last decade have shown that Ni-Ti superelastic wires are able to satisfy the ideal requirements for fixed arch-wire appliance: high flexibility, minimal distortion or plastic deformation, light constant force production over a wide range of displacements. On the other hand, many orthodontic companies produce Ni-Ti arch-wires, without giving detailed specifications on their superelastic characteristics. To improve the knowledge on real properties for these products, an experimental campaign on different commercial arch-wires has been started at the Laboratory of Biological Structure Mechanics (LABS) at the Politecnico di Milano (Italy). This work presents the first step of the research, concerning the comparison between the behaviour of four types of wires (two produced by ORMCO and two produced by 3M/Unitek) under monotonic and cyclic isothermal tensile tests. The results show significant differences between the products in terms of elastic modulus, stress values of the loading-unloading plateau, hysteresis amplitude, spring-back capacity, shape recovery capability, strain rate effect and fatigue behaviour. (orig.)

The influence of artificial salivary pH on nickel ion release and the surface morphology of stainless steel bracket-nickel-titanium archwire combinations

Directory of Open Access Journals (Sweden)

Ida Bagus Narmada

2017-06-01

Full Text Available Background: In the oral cavity, orthodontic appliances come into contact with saliva which may cause corrosion capable of changing their surface morphology due to the release of metal ions. Surface roughness can influence the effectiveness of tooth movement. One of the ions possibly released when body fluid comes into contact with brackets and archwire is nickel ion (Ni. Ni, one of the most popular components of orthodontic appliances, is, however, a toxic element that could potentially increase the likelihood of health problems such as allergic responses during treatment. Purpose: The purpose of this study was to investigate the effect of different artificial salivary pH on the ions released and the surface morphology of stainless steel (SS brackets-nickel-titanium (NiTi and archwire combinations. Methods: Brackets and archwires were analyzed by an Energy Dispersive X-Ray Detector System (EDX to determine their composition, while NiTi archwire compound was examined by means of X-ray Diffraction (XRD. The immersion test was performed at artificial salivary pH levels of 4.2; 6.5; and 7.6 at 37°C for 28 days. Ni ion release measurement was performed using an Atomic Absorption Spectroscopy (AAS. Surface morphology was analyzed by means of a Scanning Electron Microscopy (SEM. Results: The chemical composition of all orthodontic appliances contained Ni element. In addition, XRD was depicted phases not only NiTi but also Ni, Titanium, Silicon and Zinc Oleate. The immersion test showed that the highest release of Ni ions occured at a pH of 4.2, with no significant difference at various levels of pH (p=.092. There were surface morphology changes in the orthodontic appliances. It was revealed that at a pH of 4.2, the surfaces of orthodontic appliances become unhomogenous and rough compared to those at other pH concentrations. Conclusion: The reduction of pH in the artificial saliva increases the amount of released Ni ions, as well as causing changes to

Effects of thermomechanical process on the microstructure and mechanical properties of a fully martensitic titanium-based biomedical alloy.

Science.gov (United States)

Elmay, W; Prima, F; Gloriant, T; Bolle, B; Zhong, Y; Patoor, E; Laheurte, P

2013-02-01

Thermomechanical treatments have been proved to be an efficient way to improve superelastic properties of metastable β type titanium alloys through several studies. In this paper, this treatment routes, already performed on superelastic alloys, are applied to the Ti-24Nb alloy (at%) consisting of a pure martensite α'' microstructure. By short-time annealing treatments performed on the heavily deformed material, an interesting combination of a large recoverable strain of about 2.5%, a low elastic modulus (35 GPa) and a high strength (900 MPa) was achieved. These properties are shown to be due to a complex microstructure consisting of the precipitation of nanoscale (α+ω) phases in ultra-fine β grains. This microstructure allows a superelastic behavior through stress-induced α'' martensitic transformation. In this study, the microstructures were characterized by X-ray diffraction and transmission electron microscopy and the evolution of the elastic modulus and the strain recovery as a function of the applied strain was investigated through loading-unloading tensile tests. Copyright © 2012 Elsevier Ltd. All rights reserved.

Liquid phase sintering of carbides using a nickel-molybdenum alloy

International Nuclear Information System (INIS)

Barranco, J.M.; Warenchak, R.A.

1987-01-01

Liquid phase vacuum sintering was used to densify four carbide groups. These were titanium carbide, tungsten carbide, vanadium carbide, and zirconium carbide. The liquid phase consisted of nickel with additions of molybdenum of from 6.25 to 50.0 weight percent at doubling increments. The liquid phase or binder comprised 10, 20, and 40 percent by weight of the pressed powders. The specimens were tested using 3 point bending. Tungsten carbide showed the greatest improvement in bend rupture strength, flexural modulus, fracture energy and hardness using 20 percent binder with lesser amounts of molybdenum (6.25 or 12.5 wt %) added to nickel compared to pure nickel. A refinement in the carbide microstructure and/or a reduction in porosity was seen for both the titanium and tungsten carbides when the alloy binder was used compared to using the nickel alone. Curves depicting the above properties are shown for increasing amounts of molybdenum in nickel for each carbide examined. Loss of binder phase due to evaporation was experienced during heating in vacuum at sintering temperatures. In an effort to reduce porosity, identical specimens were HIP processed at 15 ksi and temperatures averaging 110 C below the sintering g temperature. The tungsten carbide and titanium carbide series containing 80 and 90 weight percent carbide phase respectively showed improvement properties after HIP while properties decreased for most other compositions

Comparative study of six rotary nickel-titanium systems and hand instrumentation for root canal preparation.

Science.gov (United States)

Guelzow, A; Stamm, O; Martus, P; Kielbassa, A M

2005-10-01

To compare ex vivo various parameters of root canal preparation using a manual technique and six different rotary nickel-titanium (Ni-Ti) instruments (FlexMaster, System GT, HERO 642, K3, ProTaper, and RaCe). A total of 147 extracted mandibular molars were divided into seven groups (n = 21) with equal mean mesio-buccal root canal curvatures (up to 70 degrees), and embedded in a muffle system. All root canals were prepared to size 30 using a crown-down preparation technique for the rotary nickel-titanium instruments and a standardized preparation (using reamers and Hedströem files) for the manual technique. Length modifications and straightening were determined by standardized radiography and a computer-aided difference measurement for every instrument system. Post-operative cross-sections were evaluated by light-microscopic investigation and photographic documentation. Procedural errors, working time and time for instrumentation were recorded. The data were analysed statistically using the Kruskal-Wallis test and the Mann-Whitney U-test. No significant differences were detected between the rotary Ni-Ti instruments for alteration of working length. All Ni-Ti systems maintained the original curvature well, with minor mean degrees of straightening ranging from 0.45 degrees (System GT) to 1.17 degrees (ProTaper). ProTaper had the lowest numbers of irregular post-operative root canal diameters; the results were comparable between the other systems. Instrument fractures occurred with ProTaper in three root canals, whilst preparation with System GT, HERO 642, K3 and the manual technique resulted in one fracture each. Ni-Ti instruments prepared canals more rapidly than the manual technique. The shortest time for instrumentation was achieved with System GT (11.7 s). Under the conditions of this ex vivo study all Ni-Ti systems maintained the canal curvature, were associated with few instrument fractures and were more rapid than a standardized manual technique. Pro

Shaping ability of the conventional nickel-titanium and reciprocating nickel-titanium file systems: a comparative study using micro-computed tomography.

Science.gov (United States)

Hwang, Young-Hye; Bae, Kwang-Shik; Baek, Seung-Ho; Kum, Kee-Yeon; Lee, WooCheol; Shon, Won-Jun; Chang, Seok Woo

2014-08-01

This study used micro-computed tomographic imaging to compare the shaping ability of Mtwo (VDW, Munich, Germany), a conventional nickel-titanium file system, and Reciproc (VDW), a reciprocating file system morphologically similar to Mtwo. Root canal shaping was performed on the mesiobuccal and distobuccal canals of extracted maxillary molars. In the RR group (n = 15), Reciproc was used in a reciprocating motion (150° counterclockwise/30° clockwise, 300 rpm); in the MR group, Mtwo was used in a reciprocating motion (150° clockwise/30° counterclockwise, 300 rpm); and in the MC group, Mtwo was used in a continuous rotating motion (300 rpm). Micro-computed tomographic images taken before and after canal shaping were used to analyze canal volume change and the degree of transportation at the cervical, middle, and apical levels. The time required for canal shaping was recorded. Afterward, each file was analyzed using scanning electron microscopy. No statistically significant differences were found among the 3 groups in the time for canal shaping or canal volume change (P > .05). Transportation values of the RR and MR groups were not significantly different at any level. However, the transportation value of the MC group was significantly higher than both the RR and MR groups at the cervical and apical levels (P file deformation was observed for 1 file in group RR (1/15), 3 files in group MR (3/15), and 5 files in group MC (5/15). In terms of shaping ability, Mtwo used in a reciprocating motion was not significantly different from the Reciproc system. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Determining cutting efficiency of nickel-titanium coronal flaring instruments used in lateral action.

Science.gov (United States)

Peters, O A; Morgental, R D; Schulze, K A; Paqué, F; Kopper, P M P; Vier-Pelisser, F V

2014-06-01

To develop a method to evaluate the cutting behaviour of nickel-titanium (NiTi) coronal flaring instruments. BioRaCe BR0 (BR), HyFlex CM 1 (HY), ProFile OS No. 2 (PF) and ProTaper Sx (PT) instruments were used in simulated coronal flaring using a lateral action against bovine dentine blocks, at 250 and 500 rpm. Cutting efficiency was assessed by three methods: first, areas of notches produced by instruments were directly measured under a stereomicroscope. Second, dentine specimens were then analysed by surface profilometry to determine the maximum cutting depth and finally by microcomputed tomography to assess the volume of removed dentine. Data were compared using parametric tests with the significance level set at 0.05. For all three methods, HY and PF were the most and the least cutting-efficient instruments, respectively (P wire, was the most efficient instrument, and increased rotational speed was associated with increased cutting efficiency. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

[Shaping ability of two nickel-titanium rotary systems in simulated S-shaped canals].

Science.gov (United States)

Luo, Hong-xia; Huang, Ding-ming; Zhang, Fu-hua; Tan, Hong; Zhou, Xue-dong

2008-01-01

To evaluate the shaping ability of two nickel-titanium rotary systems (ProTaper and Hero642) in simulated S-shaped canals. Thirty simulated S-shaped canals were randomly divided into three groups and prepared by ProTaper, Hero642, ProTaper combined with Hero642 respectively. All the canals were scanned before and after instrumentation, and the amount of material removed in the inner and outer wall and the canal width after instrumentation were measured with a computer image analysis program. There was significant difference in the amount of material removed at the inner side of apical curvature and outer side of apex between ProTaper combined with Hero642 and ProTaper files (P Hero642, and the taper of canals were better than those prepared by Hero642. ProTaper combined with Hero 642 had better shaping ability to maintain the original shape and could create good taper canals in the simulated S-shaped canal model.

Anti-corrosion performance of oxidized and oxygen plasma-implanted NiTi alloys

International Nuclear Information System (INIS)

Poon, Ray W.Y.; Ho, Joan P.Y.; Liu, Xuanyong; Chung, C.Y.; Chu, Paul K.; Yeung, Kelvin W.K.; Lu, William W.; Cheung, Kenneth M.C.

2005-01-01

Nickel-titanium shape memory alloys are useful orthopedic biomaterials on account of its super-elastic and shape memory properties. However, the problem associated with out-diffusion of harmful nickel ions in prolonged use inside the human body raises a critical safety concern. Titanium oxide films are deemed to be chemically inert and biocompatible and hence suitable to be the barrier layers to impede the leaching of Ni from the NiTi substrate to biological tissues and fluids. In the work reported in this paper, we compare the anti-corrosion efficacy of oxide films produced by atmospheric-pressure oxidation and oxygen plasma ion implantation. Our results show that the oxidized samples do not possess improved corrosion resistance and may even fare worse than the untreated samples. On the other hand, the plasma-implanted surfaces exhibit much improved corrosion resistance. Our work also shows that post-implantation annealing can further promote the anti-corrosion capability of the samples

A comparative study of the cytotoxicity and corrosion resistance of nickel-titanium and titanium-niobium shape memory alloys.

Science.gov (United States)

McMahon, Rebecca E; Ma, Ji; Verkhoturov, Stanislav V; Munoz-Pinto, Dany; Karaman, Ibrahim; Rubitschek, Felix; Maier, Hans J; Hahn, Mariah S

2012-07-01

Nickel-titanium (NiTi) shape memory alloys (SMAs) are commonly used in a range of biomedical applications. However, concerns exist regarding their use in certain biomedical scenarios due to the known toxicity of Ni and conflicting reports of NiTi corrosion resistance, particularly under dynamic loading. Titanium-niobium (TiNb) SMAs have recently been proposed as an alternative to NiTi SMAs due to the biocompatibility of both constituents, the ability of both Ti and Nb to form protective surface oxides, and their superior workability. However, several properties critical to the use of TiNb SMAs in biomedical applications have not been systematically explored in comparison with NiTi SMAs. These properties include cytocompatibility, corrosion resistance, and alterations in alloy surface composition in response to prolonged exposure to physiological solutions. Therefore, the goal of the present work was to comparatively investigate these aspects of NiTi (49.2 at.% Ti) and TiNb (26 at.% Nb) SMAs. The results from the current studies indicate that TiNb SMAs are less cytotoxic than NiTi SMAs, at least under static culture conditions. This increased TiNb cytocompatibility was correlated with reduced ion release as well as with increased corrosion resistance according to potentio-dynamic tests. Measurements of the surface composition of samples exposed to cell culture medium further supported the reduced ion release observed from TiNb relative to NiTi SMAs. Alloy composition depth profiles also suggested the formation of calcium phosphate deposits within the surface oxide layers of medium-exposed NiTi but not of TiNb. Collectively, the present results indicate that TiNb SMAs may be promising alternatives to NiTi for certain biomedical applications. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Phase transformation changes in thermocycled nickel-titanium orthodontic wires.

Science.gov (United States)

Berzins, David W; Roberts, Howard W

2010-07-01

In the oral environment, orthodontic wires will be subject to thermal fluctuations. The purpose of this study was to investigate the effect of thermocycling on nickel-titanium (NiTi) wire phase transformations. Straight segments from single 27 and 35 degrees C copper NiTi (Ormco), Sentalloy (GAC), and Nitinol Heat Activated (3M Unitek) archwires were sectioned into 5mm segments (n=20). A control group consisted of five randomly selected non-thermocycled segments. The remaining segments were thermocycled between 5 and 55 degrees C with five randomly selected segments analyzed with differential scanning calorimetry (DSC; -100150 degrees C at 10 degrees C/min) after 1000, 5000, and 10,000 cycles. Thermal peaks were evaluated with results analyzed via ANOVA (alpha=0.05). Nitinol HA and Sentalloy did not demonstrate qualitative or quantitative phase transformation behavior differences. Significant differences were observed in some of the copper NiTi transformation temperatures, as well as the heating enthalpy with the 27 degrees C copper NiTi wires (p<0.05). Qualitatively, with increased thermocycling the extent of R-phase in the heating peaks decreased in the 35 degrees C copper NiTi, and an austenite to martensite peak shoulder developed during cooling in the 27 degrees C copper NiTi. Repeated temperature fluctuations may contribute to qualitative and quantitative phase transformation changes in some NiTi wires. Copyright 2010 Academy of Dental Materials. All rights reserved.

Preliminary Investigation of the Effect of Surface Treatment on the Strength of a Titanium Carbide - 30 Percent Nickel Base Cermet

Science.gov (United States)

Robins, Leonard; Grala, Edward M

1957-01-01

Specimens of a nickel-bonded titanium carbide cermet were given the following surface treatments: (1) grinding, (2) lapping, (3) blast cleaning, (4) acid roughening, (5) oxidizing, and (6) oxidizing and refinishing. Room-temperature modulus-of-rupture and impact strength varied with the different surface treatments. Considerable strength losses resulted from the following treatments: (1) oxidation at 1600 F for 100 hours, (2) acid roughening, and (3) severe grinding with 60-grit silicon carbide abrasive. The strength loss after oxidation was partially recovered by grit blasting or diamond grinding.

Mechanical behaviour of Nd:YAG laser welded superelastic NiTi

International Nuclear Information System (INIS)

Vieira, L. Alberty; Fernandes, F.M. Braz; Miranda, R.M.; Silva, R.J.C.; Quintino, L.; Cuesta, A.; Ocana, J.L.

2011-01-01

Highlights: → The main innovations claimed are: understand rolling direction effect on mechanical cycling of laser welded NiTi. → Functionality confirmed by stabilization of hysteretic response up to 8% strain. → Welds tensile cycled exhibited superior functional mechanical behaviour. → For applied stresses of 50 MPa below UTS the joints showed superelastic behaviour. - Abstract: Joining techniques for shape memory alloys (SMA) has become of great interest, as their functional properties, namely shape memory effect (SME) and superelasticity (SE), present unique solutions for state-of-the-art applications, although limited results concerning mechanical properties are reported. This paper reports experimental work performed with Nd:YAG continuous wave laser welding of superelastic cold-rolled plates of NiTi 1 mm thick. The mechanical behaviour was evaluated by means of tensile tests performed both to failure and to cycling. The superelastic behaviour of the welded joints was observed for applied stresses close to about 50 MPa below the ultimate tensile strength of the welds. The functionality was confirmed by analyzing the stabilization of the mechanical hysteretic response to strain levels up to 8%. For tensile cycling involving strain levels larger than 6%, welded specimens were found to exhibit superior functional mechanical behaviour presenting larger recoverable strain levels. The fracture surfaces were observed by scanning electron microscopy (SEM) and the effect of the rolling direction on mechanical properties was evaluated and discussed, reinforcing the importance of joint design when laser welding these alloys.

Comparison of the mechanical properties of rotary instruments made of conventional nickel-titanium wire, M-wire, or nickel-titanium alloy in R-phase.

Science.gov (United States)

Lopes, Hélio P; Gambarra-Soares, Thaiane; Elias, Carlos N; Siqueira, José F; Inojosa, Inês F J; Lopes, Weber S P; Vieira, Victor T L

2013-04-01

This study compared the mechanical properties of endodontic instruments made of conventional nickel-titanium (NiTi) wire (K(3) and Revo-S SU), M-Wire (ProFile Vortex), or NiTi alloy in R-phase (K(3)XF). The test instruments were subjected to mechanical tests to evaluate resistance to bending (flexibility), cyclic fatigue, and torsional load in clockwise rotation. Data were statistically evaluated by the analysis of variance test and the Student-Newman-Keuls test for multiple comparisons. In the bending resistance test, flexibility decreased in the following order: K(3)XF > Revo-S SU > ProFile Vortex > K(3). The ranking in the fatigue resistance test was the following: K(3)XF > K(3) > ProFile Vortex > Revo-S SU. In the torsional assay, the angular deflection at failure decreased in the following order: K(3)XF > Revo-S SU > K(3) > ProFile Vortex. For the maximum torque values, the ranking was K(3) > K(3)XF > ProFile Vortex > Revo-S SU. The results showed that the K(3)XF instrument, which is made of NiTi alloy in R-phase, had the overall best performance in terms of flexibility, angular deflection at failure, and cyclic fatigue resistance. In addition to the alloy from which the instrument is manufactured, the design and dimensions are important determinants of the mechanical performance of endodontic instruments. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Heat treatment of nickel alloys

International Nuclear Information System (INIS)

Smith, D.F. Jr.; Clatworthy, E.F.

1975-01-01

A heat treating process is described that can be used to produce desired combinations of strength, ductility, and fabricability characteristics in heat resistant age-hardenable alloys having precipitation-hardening amounts of niobium, titanium, and/or tantalum in a nickel-containing matrix. (U.S.)

Shape memory effect alloys

International Nuclear Information System (INIS)

Koshimizu, S.

1992-01-01

Although the pseudo- or super-elasticity phenomena and the shape memory effect were known since the 1940's, the enormous curiosity and the great interest to their practical applications emerged with the development of the NITINOL alloy (Nickel-Titanium Naval Ordance Laboratory) by the NASA during the 1960's. This fact marked the appearance of a new class of materials, popularly known as shape memory effect alloys (SMEA). The objective of this work is to present a state-of-the-art of the development and applications for the SMEA. (E.O.)

Mechanical and Metallurgical Properties of Various Nickel-Titanium Rotary Instruments

Directory of Open Access Journals (Sweden)

Kyu-Sang Shim

2017-01-01

Full Text Available The aim of this study was to investigate the effect of thermomechanical treatment on mechanical and metallurgical properties of nickel-titanium (NiTi rotary instruments. Eight kinds of NiTi rotary instruments with sizes of ISO #25 were selected: ProFile, K3, and One Shape for the conventional alloy; ProTaper NEXT, Reciproc, and WaveOne for the M-wire alloy; HyFlex CM for the controlled memory- (CM- wire; and TF for the R-phase alloy. Torsional fracture and cyclic fatigue fracture tests were performed. Products underwent a differential scanning calorimetry (DSC analysis. The CM-wire and R-phase groups had the lowest elastic modulus, followed by the M-wire group. The maximum torque of the M-wire instrument was comparable to that of a conventional instrument, while those of the CM-wire and R-phase instruments were lower. The angular displacement at failure (ADF for the CM-wire and R-phase instruments was higher than that of conventional instruments, and ADF of the M-wire instruments was lower. The cyclic fatigue resistance of the thermomechanically treated NiTi instruments was higher. DSC plots revealed that NiTi instruments made with the conventional alloy were primarily composed of austenite at room temperature; stable martensite and R-phase were found in thermomechanically treated instruments.

Color stability of esthetic coatings applied to nickel-titanium archwires

Directory of Open Access Journals (Sweden)

Marcus Vinicius Neiva Nunes do REGO

Full Text Available Abstract Introduction Color stability is an important feature to be considered when using esthetic coated archwires. Objective To evaluate color changes on the surface of esthetic nickel-titanium archwires coated with Teflon (Ortho Organizers, USA or epoxy resin (Tecnident, Brazil after immersion in staining solution. Material and method Twelve 20-mm-long wire segments were used for each type of coating, which were mounted as two test specimens with a width of 7 mm each. The buccal surface of the archwires was evaluated for fluorescence and color measurements both at baseline and after immersion in a staining solution for 21 days using the VITA Easyshade® Compact spectrophotometer (Model DEASYC220. Differences in total color change according to coating type were compared using an independent samples t-test (p<0.05. The surface characteristics of as-received coated archwires were assessed using scanning electron microscopy. Result Color changes were observed on the esthetic coatings, with a significant difference between the two brands analyzed. Surface analysis revealed flaws such as wear, pitting, elevations, lack of material, granulation, grooves, cracks, and lack of standardization in the coating process in all as-received archwires, but flaws were less evident in epoxy-resin coatings. Conclusion The two esthetic coatings did not show color stability, but Teflon coatings showed a more intense color change than epoxy-resin coatings.

Observation of neutron bursts in saturation of titanium with deuterium by means of D2O electrolysis

International Nuclear Information System (INIS)

Artyukhov, V.I.; Bystritskij, V.M.; Gilev, A.I.

1991-01-01

The paper describes a correlation experiment on investigation of low-temperature nuclear dd-fusion during saturation of titanium with deuterium through electrolysis of heavy water D 2 O. The experiments with cathodes of chemically pure titanium and of titanium coated with a 0.4μm nickel layer (mass of titanium 26 g) were carried out. Emission of neutrons in the form of separate bursts was observed in the experiments with the nickel-coated cathode. The neutron emission density in the burst was found to be I n =(3.6±0.9)x10 4 s -1 . 17 refs.; 6 figs

Influence of the geometry of curved artificial canals on the fracture of rotary nickel-titanium instruments subjected to cyclic fatigue tests.

Science.gov (United States)

Lopes, Hélio P; Vieira, Márcia V B; Elias, Carlos N; Gonçalves, Lucio S; Siqueira, José F; Moreira, Edson J L; Vieira, Victor T L; Souza, Letícia C

2013-05-01

This study evaluated the influence of different features of canal curvature geometry on the number of cycles to fracture of a rotary nickel-titanium endodontic instrument subjected to a cyclic fatigue test. BioRaCe BR4C instruments (FKG Dentaire, La Chaux-de Fonds, Switzerland) were tested in 4 grooves simulating curved metallic artificial canals, each one measuring 1.5 mm in width, 20 mm in total length, and 3.5 mm in depth with a U-shaped bottom. The parameters of curvature including the radius and arc lengths and the position of the arc differed in the 4 canal designs. Fractured surfaces and helical shafts of the separated instruments were analyzed by scanning electron microscopy. The Student's t test showed that a significantly lower number of cycles to fracture values were observed for instruments tested in canals with the smallest radius, the longest arc, and the arc located in the middle portion of the canal. Scanning electron microscopic analysis of the fracture surfaces revealed morphologic characteristics of ductile fracture. Plastic deformation was not observed in the helical shaft of the fractured instruments. Curvature geometry including the radius and arc lengths and the position of the arc along the root canal influence the number of cycles to fracture of rotary nickel-titanium instruments subjected to flexural load. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Factors controlling superelastic damping capacity of SMAs

Czech Academy of Sciences Publication Activity Database

Heller, Luděk; Šittner, Petr; Pilch, Jan; Landa, Michal

2009-01-01

Roč. 18, 5-6 (2009), 603-611 ISSN 1059-9495 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z20760514 Keywords : shape memory alloys * superelastic damping * thermomechanical testing Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.592, year: 2009

Influence of SLM on compressive response of NiTi scaffolds

Science.gov (United States)

Shayesteh Moghaddam, Narges; Saedi, Soheil; Amerinatanzi, Amirhesam; Jahadakbar, Ahmadreza; Saghaian, Ehsan; Karaca, Haluk; Elahinia, Mohammad

2018-03-01

Porous Nickel-Titanium shape memory alloys (NiTi-SMAs) have attracted much attention in biomedical applications due to their high range of pure elastic deformability (i.e., superelasticity) as well as their bone-level modulus of elasticity (E≈12-20 GPa). In recent years, Selective Laser Melting (SLM) has been used to produce complex NiTi components. The focus of this study is to investigate the superelasticity and compressive properties of SLM NiTi-SMAs. To this aim, several NiTi components with different level of porosities (32- 58%) were fabricated from Ni50.8Ti (at. %) powder via SLM PXM by Phenix/3D Systems, using optimum processing parameter (Laser power-P=250 W, scanning speed-v=1250mm/s, hatch spacing-h=120μm, layer thickness-t=30μm). To tailor the superelasticity behavior at body temperature, the samples were solution annealed and aged for 15 min at 350°C. Then, transformation temperatures (TTs), superelastic response, and cyclic behavior of NiTi samples were studied. As the porosity was increased, the irrecoverable strain was observed to be higher in the samples. At the first superelastic cycle, 3.5%, 3.5%, and 2.7% strain recovery were observed for the porosity levels of 32%, 45%, and 58%, respectively. However, after 10 cycles, the superelastic response of the samples was stabilized and full strain recovery was observed. Finally, the modulus of elasticity of dense SLM NiTi was decreased from 47 GPa to 9 GPa in the first cycle by adding 58% porosity.

Photostress analysis of stress-induced martensite phase transformation in superelastic NiTi

International Nuclear Information System (INIS)

Katanchi, B.; Choupani, N.; Khalil-Allafi, J.; Baghani, M.

2017-01-01

Phase transformation in shape memory alloys is the most important factor in their unique behavior. In this paper, the formation of stress induced martensite phase transformation in a superelastic NiTi (50.8% Ni) shape memory alloy was investigated by using the photo-stress method. First, the material's fabrication procedure has been described and then the material was studied using the metallurgical tests such as differential scanning calorimetry and X-ray diffraction to characterize the material features and the mechanical tensile test to investigate the superelastic behavior. As a new method in observation of the phase transformation, photo-stress pictures showed the formation of stress induced martensite in a superelastic dog-bone specimen during loading and subsequently it's disappearing during unloading. Finally, finite element analysis was implemented using the constitutive equations derived based on the Boyd-Lagoudas phenomenological model.

Photostress analysis of stress-induced martensite phase transformation in superelastic NiTi

Energy Technology Data Exchange (ETDEWEB)

Katanchi, B. [Mechanical Engineering Faculty, Sahand University of Technology, Tabriz (Iran, Islamic Republic of); Choupani, N., E-mail: choupani@sut.ac.ir [Mechanical Engineering Faculty, Sahand University of Technology, Tabriz (Iran, Islamic Republic of); Khalil-Allafi, J. [Research Center for Advance Materials, Faculty of Materials Engineering, Sahand University of Technology, Tabriz (Iran, Islamic Republic of); Baghani, M. [School of Mechanical Engineering, College of Engineering, University of Tehran (Iran, Islamic Republic of)

2017-03-14

Phase transformation in shape memory alloys is the most important factor in their unique behavior. In this paper, the formation of stress induced martensite phase transformation in a superelastic NiTi (50.8% Ni) shape memory alloy was investigated by using the photo-stress method. First, the material's fabrication procedure has been described and then the material was studied using the metallurgical tests such as differential scanning calorimetry and X-ray diffraction to characterize the material features and the mechanical tensile test to investigate the superelastic behavior. As a new method in observation of the phase transformation, photo-stress pictures showed the formation of stress induced martensite in a superelastic dog-bone specimen during loading and subsequently it's disappearing during unloading. Finally, finite element analysis was implemented using the constitutive equations derived based on the Boyd-Lagoudas phenomenological model.

The influence of distal-end heat treatment on deflection of nickel-titanium archwire.

Science.gov (United States)

Silva, Marcelo Faria da; Pinzan-Vercelino, Célia Regina Maia; Gurgel, Júlio de Araújo

2016-01-01

The aim of this in vitro study was to evaluate the deflection-force behavior of nickel-titanium (NiTi) orthodontic wires adjacent to the portion submitted to heat treatment. A total of 106 segments of NiTi wires (0.019 x 0.025-in) and heat-activated NiTi wires (0.016 x 0.022-in) from four commercial brands were tested. The segments were obtained from 80 archwires. For the experimental group, the distal portion of each segmented archwire was subjected to heat treatment (n = 40), while the other distal portion of the same archwire was used as a heating-free control group (n = 40). Deflection tests were performed in a temperature-controlled universal testing machine. Unpaired Student's t-tests were applied to determine if there were differences between the experimental and control groups for each commercial brand and size of wire. Statistical significance was set at p wire. Heat treatment applied to the distal ends of rectangular NiTi archwires does not permanently change the elastic properties of the adjacent portions.

Vanadium and titanium determination by resorcinalhydrazide of salicylic acid

Energy Technology Data Exchange (ETDEWEB)

Karpova, O I; Pilipenko, A T; Lukachina, V V [AN Ukrainskoj SSR, Kiev. Inst. Kolloidnoj Khimii i Khimii Vody

1979-02-01

The complexing of titanium and vanadium with resorcinalhydrazyl of salicylic acid (RHSA) in water-organic media is studied. Titanium (4) forms a complex at pH 0.8-1.8, vanadium - at pH 2.5-5.6, and at pH 7.6-9.8. The complexes are well extracted by polar and nonpolar solvents from acid solutions. The techniques are developed for the determination of titanium and vanadium by the RHSA agent in nickel alloys.

Fatigue of Nitinol: The state-of-the-art and ongoing challenges.

Science.gov (United States)

Mahtabi, M J; Shamsaei, Nima; Mitchell, M R

2015-10-01

Nitinol, a nearly equiatomic alloy of nickel and titanium, has been considered for a wide range of applications including medical and dental devices and implants as well as aerospace and automotive components and structures. The realistic loading condition in many of these applications is cyclic; therefore, fatigue is often the main failure mode for such components and structures. The fatigue behavior of Nitinol involves many more complexities compared with traditional metal alloys arising from its uniqueness in material properties such as superelasticity and shape memory effects. In this paper, a review of the present state-of-the-art on the fatigue behavior of superelastic Nitinol is presented. Various aspects of fatigue of Nitinol are discussed and microstructural effects are explained. Effects of material preparation and testing conditions are also reviewed. Finally, several conclusions are made and recommendations for future works are offered. Copyright © 2015 Elsevier Ltd. All rights reserved.

The biocompatibility of dense and porous Nickel-Titanium produced by selective laser melting

Energy Technology Data Exchange (ETDEWEB)

Habijan, T., E-mail: Tim.Habijan@rub.de [Surgical Research, Department of Surgery, BG Kliniken Bergmannsheil, Ruhr-University Bochum, Buerkle-de-la-Camp-Platz 1, 44789 Bochum (Germany); Haberland, C.; Meier, H. [Institute Product and Service Engineering, Ruhr-University Bochum (Germany); Frenzel, J. [Institute for Materials, Ruhr-University Bochum (Germany); Wittsiepe, J. [Department of Hygiene, Social and Environmental Medicine, Ruhr-University Bochum (Germany); Wuwer, C.; Greulich, C.; Schildhauer, T.A.; Koeller, M. [Surgical Research, Department of Surgery, BG Kliniken Bergmannsheil, Ruhr-University Bochum, Buerkle-de-la-Camp-Platz 1, 44789 Bochum (Germany)

2013-01-01

Nickel-Titanium shape memory alloys (NiTi-SMA) are of biomedical interest due to their unusual range of pure elastic deformability and their elastic modulus, which is closer to that of bone than any other metallic or ceramic material. Newly developed porous NiTi, produced by Selective Laser Melting (SLM), is currently under investigation as a potential carrier material for human mesenchymal stem cells (hMSC). SLM enables the production of highly complex and tailor-made implants for patients on the basis of CT data. Such implants could be used for the reconstruction of the skull, face, or pelvis. hMSC are a promising cell type for regenerative medicine and tissue engineering due to their ability to support the regeneration of critical size bone defects. Loading porous SLM-NiTi implants with autologous hMSC may enhance bone growth and healing for critical bone defects. The purpose of this study was to assess whether porous SLM-NiTi is a suitable carrier for hMSC. Specimens of varying porosity and surface structure were fabricated via SLM. hMSC were cultured for 8 days on NiTi specimens, and cell viability was analyzed using two-color fluorescence staining. Viable cells were detected on all specimens after 8 days of cell culture. Cell morphology and surface topography were analyzed by scanning electron microscopy (SEM). Cell morphology and surface topology were dependent on the orientation of the specimens during SLM production. The Nickel ion release can be reduced significantly by aligned laser processing conditions. The presented results clearly attest that both dense SLM-NiTi and porous SLM-NiTi are suitable carriers for hMSC. Nevertheless, before carrying out in vivo studies, some work on optimization of the manufacturing process and post-processing is required. - Highlights: Black-Right-Pointing-Pointer Specimens, varying in porosity and surface structure were produced via SLM. Black-Right-Pointing-Pointer Biocompatibility of these specimens was analyzed. Black

Evaluation of deflection forces of orthodontic wires with different ligation types

Directory of Open Access Journals (Sweden)

José Fernando Castanha HENRIQUES

2017-07-01

Full Text Available Abstract The aim of this study was to evaluate deflection forces of orthodontic wires of different alloys engaged into conventional brackets using several ligation types. Stainless steel, conventional superelastic nickel-titanium and thermally activated nickel-titanium archwires tied into conventional brackets by a ring-shaped elastomeric ligature (RSEL, a 8-shaped elastomeric ligature (8SEL and a metal ligature (ML were tested. A clinical simulation device was created especially for this study and forces were measured with an Instron Universal Testing Machine. For the testing procedure, the block representing the maxillary right central incisor was moved 0.5 and 1 mm bucco-lingually at a constant speed of 2 mm/min, and the forces released by the wires were recorded, in accordance with the ISO 15841 guidelines. In general, the RSEL showed lighter forces, while 8SEL and ML showed higher values. At the 0.5 mm deflection, the 8SEL presented the greatest force, but at the 1.0 mm deflection the ML had a statistically similar force. Based on our evaluations, to obtain lighter forces, the thermally activated nickel-titanium wire with the RSEL are recommended, while the steel wire with the 8SEL or the ML are recommended when larger forces are desired. The ML exhibited the highest force increase with increased deflections, compared with the elastomeric ligatures.

Long-term superelastic cycling at nano-scale in Cu-Al-Ni shape memory alloy micropillars

Energy Technology Data Exchange (ETDEWEB)

San Juan, J., E-mail: jose.sanjuan@ehu.es; Gómez-Cortés, J. F. [Dpto. Física Materia Condensada, Facultad de Ciencia y Tecnología, Univ. del País Vasco UPV/EHU, Apdo. 644, 48080 Bilbao (Spain); López, G. A.; Nó, M. L. [Dpto. Física Aplicada II, Facultad de Ciencia y Tecnología, Univ. del País Vasco UPV/EHU, Apdo. 644, 48080 Bilbao (Spain); Jiao, C. [FEI, Achtseweg Noord 5, 5651 GG Eindhoven (Netherlands)

2014-01-06

Superelastic behavior at nano-scale has been studied along cycling in Cu-Al-Ni shape memory alloy micropillars. Arrays of square micropillars were produced by focused ion beam milling, on slides of [001] oriented Cu-Al-Ni single crystals. Superelastic behavior of micropillars, due to the stress-induced martensitic transformation, has been studied by nano-compression tests during thousand cycles, and its evolution has been followed along cycling. Each pillar has undergone more than thousand cycles without any detrimental evolution. Moreover, we demonstrate that after thousand cycles they exhibit a perfectly reproducible and completely recoverable superelastic behavior.

Martensitic Transformation and Superelasticity in Fe-Mn-Al-Based Shape Memory Alloys

Science.gov (United States)

Omori, Toshihiro; Kainuma, Ryosuke

2017-12-01

Ferrous shape memory alloys showing superelasticity have recently been obtained in two alloy systems in the 2010s. One is Fe-Mn-Al-Ni, which undergoes martensitic transformation (MT) between the α (bcc) parent and γ' (fcc) martensite phases. This MT can be thermodynamically understood by considering the magnetic contribution to the Gibbs energy, and the β-NiAl (B2) nanoprecipitates play an important role in the thermoelastic MT. The temperature dependence of critical stress for the MT is very small (about 0.5 MPa/°C) due to the small entropy difference between the parent and martensite phases in the Fe-Mn-Al-Ni alloy, and consequently, superelasticity can be obtained in a wide temperature range from cryogenic temperature to about 200 °C. Microstructural control is of great importance for obtaining superelasticity, and the relative grain size is among the most crucial factors.

Shape memory and superelastic behavior of Ti-7.5Nb-4Mo-1Sn alloy

International Nuclear Information System (INIS)

Zhang, D.C.; Lin, J.G.; Jiang, W.J.; Ma, M.; Peng, Z.G.

2011-01-01

Research highlights: → A Ti-based shape memory alloy, Ti-7.5Nb-4Mo-1Sn, was designed. → The martensitic transformation start temperature of the alloy, M s , is 261 K. → The alloy exhibits good shape memory and superelastic behaviors. → The alloy also shows a good superelastic stability at room temperature. → The Ti-5Mo-7.5Nb-1Sn alloy has a potential application as a biomedical material. -- Abstract: In the present work, a Ti-based shape memory alloy with the composition of Ti-7.5Nb-4Mo-1Sn was designed based on the d-electron orbit theory. The shape memory and superelastic behavior of the alloy were investigated. It is found that the martensitic transformation temperature of the alloy is near 261 K. The tensile and the thermal cycling testing results show that the alloy exhibits the stable shape memory effect and superelasticity at room temperature. The maximum recovered strain of the alloy is 4.83%.

Maxillary molar derotation and distalization by using a nickel-titanium wire fabricated on a setup model.

Science.gov (United States)

Jung, Jong Moon; Wi, Young Joo; Koo, Hyun Mo; Kim, Min Ji; Chun, Youn Sic

2017-07-01

The purpose of this article is to introduce a simple appliance that uses a setup model and a nickel-titanium (Ni-Ti) wire for correcting the mesial rotation and drift of the permanent maxillary first molar. The technique involves bonding a Ni-Ti wire to the proper position of the target tooth on a setup model, followed by the fabrication of the transfer cap for indirect bonding and its transfer to the patient's teeth. This appliance causes less discomfort and provides better oral hygiene for the patients than do conventional appliances such as the bracket, pendulum, and distal jet. The treatment time is also shorter with the new appliance than with full-fixed appliances. Moreover, the applicability of the new appliance can be expanded to many cases by using screws or splinting with adjacent teeth to improve anchorage.

Corrosion resistance of stainless steel, nickel-titanium, titanium molybdenum alloy, and ion-implanted titanium molybdenum alloy archwires in acidic fluoride-containing artificial saliva: An in vitro study

Directory of Open Access Journals (Sweden)

Venith Jojee Pulikkottil

2016-01-01

Full Text Available Objective: (1 To evaluate the corrosion resistance of four different orthodontic archwires and to determine the effect of 0.5% NaF (simulating high fluoride-containing toothpaste of about 2250 ppm on corrosion resistance of these archwires. (2 To assess whether surface roughness (Ra is the primary factor influencing the corrosion resistance of these archwires. Materials and Methods: Four different archwires (stainless steel [SS], nickel-titanium [NiTi], titanium molybdenum alloy [TMA], and ion-implanted TMA were considered for this study. Surface characteristics were analyzed using scanning electron microscopy, atomic force microscopy (AFM, and energy dispersive spectroscopy. Linear polarization test, a fast electrochemical technique, was used to evaluate the corrosion resistance, in terms of polarization resistance of four different archwires in artificial saliva with NaF concentrations of 0% and 0.5%. Statistical analysis was performed by one-way analysis of variance. Results: The potentiostatic study reveals that the corrosion resistance of low-friction TMA (L-TMA > TMA > NiTi > SS. AFM analysis showed the surface Ra of TMA > NiTi > L-TMA > SS. This indicates that the chemical composition of the wire is the primary influential factor to have high corrosion resistance and surface Ra is only secondary. The corrosion resistance of all wires had reduced significantly in 0.5% acidic fluoride-containing artificial saliva due to formation of fluoride complex compound. Conclusion: The presence of 0.5% NaF in artificial saliva was detrimental to the corrosion resistance of the orthodontic archwires. Therefore, complete removal of residual high-fluorinated toothpastes from the crevice between archwire and bracket during tooth brushing is mandatory.

Mechanical properties of superelastic Cu–Al–Be wires at cold temperatures for the seismic protection of bridges

International Nuclear Information System (INIS)

Zhang Yunfeng; Zhu Songye; Camilleri, Joseph A

2008-01-01

This paper examines the suitability of superelastic copper–aluminum–beryllium (Cu–Al–Be) alloy wires for the seismic protection of bridges in cold regions. Experimental results for the mechanical properties of superelastic Cu–Al–Be alloy wires at a variety of temperatures and loading rates are presented. This research is motivated by the recent use of shape memory alloys for bridge restrainers subject to harsh winter conditions, especially in cold regions. Bridge restrainers made of superelastic Cu–Al–Be wire strands are expected to be used for protecting bridge decks from excessive displacement when subjected to strong earthquakes. Using a temperature chamber, superelastic Cu–Al–Be wires with a diameter of 1.4 mm were tested under uniaxial cyclic loading at various loading rates and cold temperatures. The test results from 23 to −50 °C demonstrate that Cu–Al–Be exhibits superelastic behavior at cold temperatures down to −85 °C. It is also found that with decreasing temperature the transformation plateau stress is reduced while its fatigue life increases under cyclic testing

Compressive and fatigue behavior of beta-type titanium porous structures fabricated by electron beam melting

International Nuclear Information System (INIS)

Liu, Y.J.; Wang, H.L.; Li, S.J.; Wang, S.G.; Wang, W.J.; Hou, W.T.; Hao, Y.L.; Yang, R.; Zhang, L.C.

2017-01-01

β-type titanium porous structure is a new class of solution for implant because it offers excellent combinations of high strength and low Young's modulus. This work investigated the influence of porosity variation in electron beam melting (EBM)-produced β-type Ti2448 alloy samples on the mechanical properties including super-elastic property, Young's modulus, compressive strength and fatigue properties. The relationship between the misorientation angle of adjacent grains and fatigue crack deflection behaviors was also observed. The super-elastic property is improved as the porosity of samples increases because of increasing tensile/compressive ratio. For the first time, the position of fatigue crack initiation is defined in stress-strain curves based on the variation of the fatigue cyclic loops. The unique manufacturing process of EBM results in the generation of different sizes of grains, and the apparent fatigue crack deflection occurs at the grain boundaries in the columnar grain zone due to substantial misorientation between adjacent grains. Compared with Ti-6Al-4V samples, the Ti2448 porous samples exhibit a higher normalized fatigue strength owing to super-elastic property, greater plastic zone ahead of the fatigue crack tip and the crack deflection behavior. - Highlights: • The super-elastic property is improved with increasing porosity of Ti2448 porous samples. • The position of fatigue crack initiation on the strain curve is defined. • The unique EBM-produced microstructure leads to apparent fatigue crack deflection occurring at columnar grain boundary. • Ti2448 porous samples display only half of the Young's modulus of Ti-6Al-4V porous samples at same fatigue strength level.

Friction produced by types of elastomeric ligatures in treatment mechanics with the preadjusted appliance.

Science.gov (United States)

Baccetti, Tiziano; Franchi, Lorenzo

2006-03-01

The objective was to compare the frictional forces generated by new nonconventional passive elastomeric ligatures (NCL) and conventional elastomeric ligatures (CL) under dry conditions. An experimental model reproducing the right buccal segment of the upper arch and consisting of five stainless steel 0.022-inch preadjusted brackets (from the second premolar through the central incisor) was used to assess both static and kinetic frictional forces produced by NCL and CL. The frictional forces generated by the 0.019 x 0.025-inch stainless steel wire with the two types of elastomeric ligatures were recorded by sliding the wire into the aligned brackets. The friction produced by the 0.014-inch superelastic nickel titanium wire was evaluated both in the presence of aligned brackets and of three-mm misaligned canine bracket. The amount of both static and kinetic frictions were minimal (<10 g) in the NCL group in the presence of aligned brackets with both types of wires, whereas it ranged from a minimum of 95.6 g for the 0.014-inch superelastic nickel titanium wire to a maximum of 590.7 g for the 0.019 x 0.025-inch stainless steel wire when using CL. The amount of both static and kinetic frictions in the presence of a misaligned canine bracket in the NCL group were less than half of that shown by the CL group. A recently developed passive ligature system is able to produce significantly lower levels of frictional forces in vitro when compared with conventional elastomeric modules.

Effect of grain size on superelasticity in Fe-Mn-Al-Ni shape memory alloy wire

Directory of Open Access Journals (Sweden)

T. Omori

2013-09-01

Full Text Available Effects of grain size on superelastic properties in Fe-34Mn-15Al-7.5Ni alloy wires with a ⟨110⟩ fiber-texture were investigated by cyclic tensile tests. It was confirmed that the critical stress for induced martensitic transformation and the superelastic strain are functions of relative grain size d/D (d: mean grain diameter, D: wire diameter, and that the critical stress is proportional to (1–d/D2 as well as in Cu-based shape memory alloys. A large superelastic strain of about 5% was obtained in the specimen with a large relative grain size over d/D = 1.

Passive base isolation with superelastic nitinol SMA helical springs

International Nuclear Information System (INIS)

Huang, Bin; Zhang, Haiyang; Wang, Han; Song, Gangbing

2014-01-01

Seismic isolation of structures such as multi-story buildings, nuclear reactors, bridges, and liquid storage tanks should be designed to preserve structural integrity. By implementing seismic isolation technology, the deformation of superstructures can be dramatically reduced, consequently helping to protect their safety as well. In this paper, an innovative type of passive base isolation system, which is mainly composed of superelastic nitinol SMA helical springs, is developed. In order to verify the effectiveness of the proposed system, a two-story experimental steel frame model is constructed, and two superelastic SMA helical springs are thermo-mechanically built in the laboratory. To describe the nonlinear mechanical properties of the superelastic SMA helical springs under reciprocating load, a phenomenological model is presented in terms of a series of tensile tests. Afterwards, a numerical model of the two-story frame with the suggested isolation system is set up to simulate the response of the isolated frame subjected to an earthquake. Both the experimental and the numerical simulation results indicate that the proposed base isolation system can remarkably suppress structural vibrations and has improved isolation effects when compared with a steel spring isolation system. Due to the capabilities of energy dissipation as well as fully re-centering, it is very applicable to utilize the suggested isolation system in base isolated structures to resist earthquakes. (paper)

Wet-Spun Superelastic Graphene Aerogel Millispheres with Group Effect.

Science.gov (United States)

Zhao, Xiaoli; Yao, Weiquan; Gao, Weiwei; Chen, Hao; Gao, Chao

2017-09-01

Graphene aerogel has attracted great attention due to its unique properties, such as ultralow density, superelasticity, and high specific surface area. It shows huge potential in energy devices, high-performance pressure sensors, contaminates adsorbents, and electromagnetic wave absorbing materials. However, there still remain some challenges to further promote the development and real application of graphene aerogel including cost-effective scalable fabrication and miniaturization with group effect. This study shows millimeter-scale superelastic graphene aerogel spheres (GSs) with group effect and multifunctionality. The GSs are continuously fabricated on a large scale by wet spinning of graphene oxide liquid crystals followed by facile drying and thermal annealing. Such GS has an unusual core-shell structure with excellent elasticity and specific strength. Significantly, both horizontally and vertically grouped spheres exhibit superelasticity comparable to individual spheres, enabling it to fully recover at 95% strain, and even after 1000 compressive cycles at 70% strain, paving the way to wide applications such as pressure-elastic and adsorbing materials. The GS shows a press-fly behavior with an extremely high jump velocity up to 1.2 m s -1 . For the first time, both free and oil-adsorbed GSs are remotely manipulated on water by electrostatic charge due to their ultralow density and hydrophobic properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The biocompatibility of dense and porous Nickel-Titanium produced by selective laser melting.

Science.gov (United States)

Habijan, T; Haberland, C; Meier, H; Frenzel, J; Wittsiepe, J; Wuwer, C; Greulich, C; Schildhauer, T A; Köller, M

2013-01-01

Nickel-Titanium shape memory alloys (NiTi-SMA) are of biomedical interest due to their unusual range of pure elastic deformability and their elastic modulus, which is closer to that of bone than any other metallic or ceramic material. Newly developed porous NiTi, produced by Selective Laser Melting (SLM), is currently under investigation as a potential carrier material for human mesenchymal stem cells (hMSC). SLM enables the production of highly complex and tailor-made implants for patients on the basis of CT data. Such implants could be used for the reconstruction of the skull, face, or pelvis. hMSC are a promising cell type for regenerative medicine and tissue engineering due to their ability to support the regeneration of critical size bone defects. Loading porous SLM-NiTi implants with autologous hMSC may enhance bone growth and healing for critical bone defects. The purpose of this study was to assess whether porous SLM-NiTi is a suitable carrier for hMSC. Specimens of varying porosity and surface structure were fabricated via SLM. hMSC were cultured for 8 days on NiTi specimens, and cell viability was analyzed using two-color fluorescence staining. Viable cells were detected on all specimens after 8 days of cell culture. Cell morphology and surface topography were analyzed by scanning electron microscopy (SEM). Cell morphology and surface topology were dependent on the orientation of the specimens during SLM production. The Nickel ion release can be reduced significantly by aligned laser processing conditions. The presented results clearly attest that both dense SLM-NiTi and porous SLM-NiTi are suitable carriers for hMSC. Nevertheless, before carrying out in vivo studies, some work on optimization of the manufacturing process and post-processing is required. Copyright © 2012 Elsevier B.V. All rights reserved.

Comparison of titanium cable tension band and nickel-titanium patella concentrator for patella fractures.

Science.gov (United States)

Zhao, Quan-Ming; Gu, Xiao-Feng; Cheng, Li; Feng, De-Hong

2017-07-01

Patellar fractures account for approximately 1% of all fractures. Due to the patella's importance as regards the extensor mechanism, effort should be made to preserve the patella. Several operative treatment methods have been introduced for patella fractures. This study aims to compare the clinical effect of a titanium cable tension band and nickeltitanium (NiTi) patella concentrator (NT-PC) in treating patella fractures. Thirty-nine patients with patella fractures were enrolled in this retrospective study. All the patients were treated via the open reduction internal fixation procedure using a titanium cable tension band or NT-PC. All the patients were followed up over an average period of 13 months. The main outcome measures were operation time, time of fracture union, postoperative complications, and Böstman knee scores. Statistical analyses were conducted between the 2 groups. All the patients were operated on successfully. The operation time of the NT-PC treatment group was less than that of the titanium cable tension band treatment group (p cable tension band and NT-PC groups, respectively. No significant difference was observed between the excellent and good results (p > 0.05). Both titanium cable tension band and NT-PC showed good efficacy for the treatment of patellar fractures. NT-PC fixation, a new option for the treatment of patella fractures, is a simple and effective fixation method.

Thermoelectric transport properties of polycrystalline titanium diselenide co-intercalated with nickel and titanium using spark plasma sintering

Energy Technology Data Exchange (ETDEWEB)

Holgate, T.C. [Department of Energy Storage and Conversion, Technical University of Denmark, Riso Campus, 4000 Roskilde (Denmark); Zhu, S.; Zhou, M. [Department of Physics and Astronomy, Clemson University, Clemson, SC 29634 (United States); Bangarigadu-Sanasy, S.; Kleinke, H. [Department of Chemistry, University of Waterloo, Waterloo, Ontario, N2L 3G1 (Canada); He, J. [Department of Physics and Astronomy, Clemson University, Clemson, SC 29634 (United States); Tritt, T.M., E-mail: ttritt@clemson.edu [Department of Physics and Astronomy, Clemson University, Clemson, SC 29634 (United States)

2013-01-15

Polycrystalline samples of nickel intercalated (0-5%) TiSe{sub 2} were attempted via solid-state reaction in evacuated quartz tubes followed by densification using a spark plasma sintering process. X-ray diffraction data indicated that mixed NiSe{sub 2} and TiSe{sub 2} phases were present after initial synthesis by solid-state reaction, but a pure TiSe{sub 2} phase was present after the spark plasma sintering. While EPMA data reveals the stoichiometry to be near 1:1.8 (Ti:Se) for all samples, comparisons of the measured bulk densities to the theoretical densities suggest that the off stoichiometry is a result of the co-intercalation of both Ni and Ti rather than Se vacancies. Due to the presence of excess Ti (0.085-0.130 per formula) in the van der Waals gap of all the samples, the sensitive electron-hole balance is offset by the additional Ti-3d electrons, leading to an increase in the thermopower (n-type) over pristine, stoichiometric TiSe{sub 2}. The effects of the co-intercalation of both Ni and Ti in TiSe{sub 2} on the structural, thermal, and electrical properties are discussed herein. - Graphical abstract: Co-intercalation of nickel and excess titanium into the van der Waals gap of TiSe{sub 2} via solid state synthesis followed by spark plasma sintering results in a systematic shift in the ratio of hole and electron carrier concentration, which is close to unity for pristine TiSe{sub 2}. This directly affects the electrical transport properties, and as the structural disorder induced by intercalation suppresses the lattice thermal conductivity, co-intercalation is an effective route to enhance the thermoelectric properties of transition metal diselenides. Highlights: Black-Right-Pointing-Pointer Single phase bulk Ni and Ti co-intercalated TiSe{sub 2} samples prepared by spark plasma sintering. Black-Right-Pointing-Pointer Density and X-ray diffraction suggest that the Ni and excess Ti are ordered in the Van der Waals gap. Black-Right-Pointing-Pointer Co

Investigations on the binary systems of boron with chromium, columbium, nickel, and thorium, including a discussion of the Phase TiB in the titanium-boron system

Energy Technology Data Exchange (ETDEWEB)

Andersson, L H; Kiessling, R

1950-01-01

Investigations on the binary systems chromium-, columbium-, nickel-, and thorium-boron are reported. The titanium-boron system is discussed, and it is shown that the phase TiB, previously assumed to have zincblende structure, probably has a face-centered titanium lattice with boron in the octahedral interstices. In the chromium-boron system, the structure of the eta phase has been determined. It has the composition Cr/sub 3/B/sub 4/ and is isomorphous with Ta/sub 3/B/sub 4/ and Mn/sub 3/B/sub 4/. Some data for the delta phase are also given. For the columbium-boron system, a phase analysis has been carried out. The structures of three of the intermediary phases, CbB, Cb/sub 3/B/sub 2/, and CbB/sub 2/ (with extended homogeneity range), have been determined. They are isomorphous with corresponding phases of the tantalum-boron system. A brief phase analysis of the nickel-boron system showed the existence of a phase with lower boron content than Ni/sub 2/B, which has not been previously reported. In the thorium-boron system a new phase, probably with a complicated structure, was found with a boron content of about 50 at. %.

Thermal neutron capture cross section of chromium, vanadium, titanium and nickel isotopes

International Nuclear Information System (INIS)

Venturini, L.; Pecequilo, B.R.S.

1990-04-01

The thermal neutron cross section of chromium, vanadium, titanium and nickel can be determined by measuring the pair spectrum of prompt gamma-rays emitted targets of these elements are irradiated by a thermal neutron beam. Such measurements were carried out by irradiating the natural element mixed with a nitrogen standard (melamine) in the tangential beam hole of the IEA-R1 research reactor. The pair spectrometer efficiency calibration curve in the 1.5 to 11 MeV energy range was performed with a melamine plus ammonium chloride mixed target. The cross section was calculated for the most prominent gamma transitions of each isotope, using nitrogen as standard and averaged over the obtained values. The resulting mean cross sections are as follows: (13.4 ± 0.7)b for 50 Cr, (0.79 ± 0,02)b for 52 Cr, (18.1 ± 0,7)b for 53 Cr, (4.9 ± 0.2)b for 51 V, (8.4 ± 0.1)b for 48 Ti, (4.41 ± 0.08)b 58 Ni, (2.54 ± 0.07)b for 60 Ni, (15.2 ± 0.5)b for 62 Ni and (1.6 ± 0.1) for 64 Ni. (author) [pt

The effect of brushing motion on the cyclic fatigue of rotary nickel titanium instruments

Directory of Open Access Journals (Sweden)

Gianluca Gambarini

2010-12-01

Full Text Available The goal of the study is to evaluate if the use of rotary nickel-titanium (RNT instruments, as Hedstroem files, is safe. Twelve twisted files (TF RNT instruments size 06-25 were selected and randomly divided in 2 groups of 6 instruments each. Group A (new instruments were used as control. Group B (test instruments were clinically used only as Hedstroem files in a canal that had been previously instrumented to the working length with other 06-25 RNT instruments. Group B instruments were used only in the straight portion of the canal (1 minute at 1000 rpm. A cyclic fatigue test was performed for each instrument of groups. Data were statistically analyzed (Student's t-test. Results showed no significant difference (P > 0.05 between groups A and B. Data confirmed that the use of TF instruments as Hedstroem files is a safe procedure. Cross section images and volumes of the same instrument, before and after cyclic fatigue testing, have been obtained by means of microtomographic analysis to evaluate possible microstructure alterations.

A comparison of space closure rates between preactivated nickel-titanium and titanium-molybdenum alloy T-loops: a randomized controlled clinical trial.

Science.gov (United States)

Keng, Feng-Yi; Quick, Andrew N; Swain, Michael V; Herbison, Peter

2012-02-01

The purpose of this study was to conduct a prospective randomized controlled clinical trial to evaluate the rate of space closure and tooth angulation during maxillary canine retraction using preactivated T-loops made from titanium-molybdenum alloy (TMA) and nickel-titanium (NiTi). Twelve patients (six males and six females) aged between 13 and 20 years who had upper premolar extractions were included, and each acted as their own control, with a NiTi T-loop allocated to one quadrant and TMA to the other using a split mouth block randomization design. The loops were activated 3 mm at each visit to deliver a load of approximately 150 g to the upper canine teeth. Maxillary dental casts, taken at the first and each subsequent monthly visit, were used to evaluate changes in extraction space and canine angulation. All used T-loops were compared with unused loops in order to assess distortion. Mixed model statistical analysis was used to adjust for confounding variables. The mean rate of canine retraction using preactivated NiTi and TMA T-loops was 0.91 mm/month (±0.46) and 0.87 mm/month (±0.34), respectively. The canine tipping rates were 0.71 degrees/month (±2.34) for NiTi and 1.15 degrees/month (±2.86) for TMA. Both the rate of space closure and the tipping were not significantly different between the two wire types. The average percentage distortion of the TMA T-loop was 10 times greater than that of the NiTi loops when all other variables were matched. There was no difference in the rate of space closure or tooth angulation between preactivated TMA or NiTi T-loops when used to retract upper canines. The NiTi loops possessed a greater ability to retain and return to their original shapes following cyclical activation.

Fatigue testing of controlled memory wire nickel-titanium rotary instruments.

Science.gov (United States)

Shen, Ya; Qian, Wei; Abtin, Houman; Gao, Yuan; Haapasalo, Markus

2011-07-01

To improve the fracture resistance of nickel-titanium (NiTi) files, manufacturers have introduced new alloys to manufacture NiTi files and developed new manufacturing processes. This study was aimed to examine the fatigue behavior of NiTi instruments from a novel controlled memory NiTi wire (CM Wire). Instruments of ProFile, Typhoon (TYP), Typhoon CM (TYP CM), DS-SS0250425NEYY (NEYY), and DS-SS0250425NEYY CM (NEYY CM) (DS Dental, Johnson City, TN) all size 25/.04 were subjected to rotational bending at the curvature of 35° and 45° in air at the temperature of 23° ± 2°C, and the number of revolutions to fracture (N(f)) was recorded. The fracture surface of all fragments was examined by a scanning electron microscope. The crack-initiation sites, the percentage of dimple area to the whole fracture cross-section, and the surface strain amplitude (ε(a)) were noted. The new alloy yielded an improvement of over three to eight times in N(f) of CM files than that of conventional NiTi files (P wire (58%-100%) had one crack origin. The values of the fraction area occupied by the dimple region were significantly smaller on CM NiTi instruments compared with conventional NiTi instruments (P wire at both curvatures (P Wire had a significantly higher N(f) and lower surface strain amplitude than the conventional NiTi wire files with identical design. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Ni-Ti Alloys for Tribological Applications: The Effects of Serendipity on Research and Development

Science.gov (United States)

DellaCorte, Christopher

2016-01-01

Novel superelastic materials based upon Nickel-Titanium (NiTi) alloys are an emerging technology that almost escaped recognition. Though steel is the dominant material of choice for mechanical components (bearings and gears) it has intrinsic limitations related to corrosion and plastic deformation. In 2004, at the request of a small manufacturing firm, Nitinol 60 was assessed as an alternative to bearing steel. Early investigations showed it to be hard and impervious to aqueous corrosion but its tribological properties were not fully explored. Conventional wisdom in the field of tribology suggests that alloys rich in titanium are poor candidate bearing materials but NiTi, an intermetallic, demonstrates that such thinking can be and often is, wrong. Though early stage tests reveal acceptable friction and wear behavior, extensive materials engineering and processing development was essential in producing the precision microstructures needed for long-life bearings and gears. In the course of exploring this new material system other game-changing and unexpected properties, such as superelastic resilience, were observed. Today, the aerospace community is exploiting the unique characteristics of the NiTi alloy materials to solve problems on earth, underwater and in space. A fortunate decision to acknowledge a single industrial request turned out to be the key to an entirely new technology.

Tensile and fatigue behavior of polymer composites reinforced with superelastic SMA strands

Science.gov (United States)

Daghash, Sherif M.; Ozbulut, Osman E.

2018-06-01

This study explores the use of superelastic shape memory alloy (SMA) strands, which consist of seven individual small-diameter wires, in an epoxy matrix and characterizes the tensile and fatigue responses of the developed SMA/epoxy composites. Using a vacuum assisted hand lay-up technique, twelve SMA fiber reinforced polymer (FRP) specimens were fabricated. The developed SMA-FRP composites had a fiber volume ratio of 50%. Tensile response of SMA-FRP specimens were characterized under both monotonic loading and increasing amplitude loading and unloading cycles. The degradation in superelastic properties of the developed SMA-FRP composites during fatigue loading at different strain amplitudes was investigated. The effect of loading rate on the fatigue response of SMA-FRP composites was also explored. In addition, fractured specimens were examined using the scanning electron microscopy (SEM) technique to study the failure mechanisms of the tested specimens. A good interfacial bonding between the SMA strands and epoxy matrix was observed. The developed SMA-FRP composites exhibited good superelastic behavior at different strain amplitudes up to at least 800 cycle after which significant degradation occurred.

Multi-objective optimization of a type of ellipse-parabola shaped superelastic flexure hinge

Directory of Open Access Journals (Sweden)

Z. Du

2016-05-01

Full Text Available Flexure hinges made of superelastic materials is a promising candidate to enhance the movability of compliant mechanisms. In this paper, we focus on the multi-objective optimization of a type of ellipse-parabola shaped superelastic flexure hinge. The objective is to determine a set of optimal geometric parameters that maximizes the motion range and the relative compliance of the flexure hinge and minimizes the relative rotation error during the deformation as well. Firstly, the paper presents a new type of ellipse-parabola shaped flexure hinge which is constructed by an ellipse arc and a parabola curve. Then, the static responses of superelastic flexure hinges are solved via non-prismatic beam elements derived by the co-rotational approach. Finite element analysis (FEA and experiment tests are performed to verify the modeling method. Finally, a multi-objective optimization is performed and the Pareto frontier is found via the NSGA-II algorithm.

Clausius–Duhem inequality description of superelasticity in Ni–Ti polycrystal as a dissipative process

International Nuclear Information System (INIS)

Yasuda, Yohei; Kato, Hiroyuki; Sasaki, Kazuaki

2012-01-01

Superelasticity in Ni–Ti polycrystal is examined in terms of the second law of thermodynamics. As a consequence of the law, both the phase equilibrium and the dissipation of mechanical energy during the stress-induced martensitic transformation have been formulated simultaneously by means of the Clausius–Duhem inequality. The flow stress of superelasticity has been derived as the function of temperature. The energy dissipated in the shape memory effect is briefly discussed.

Corrosion considerations of high-nickel alloys and titanium alloys for high-level radioactive waste disposal containers

International Nuclear Information System (INIS)

Gdowski, G.E.; McCright, R.D.

1991-07-01

Corrosion resistant materials are being considered for the metallic barrier of the Yucca Mountain Project's high-level radioactive waste disposal containers. High nickel alloys and titanium alloys have good corrosion resistance properties and are considered good candidates for the metallic barrier. The localized corrosion phenomena, pitting and crevice corrosion, are considered as potentially limiting for the barrier lifetime. An understanding of the mechanisms of localized corrosion of how various parameters affect it will be necessary for adequate performance assessments of candidate container materials. Examples of some of the concerns involving candidate container materials. Examples of some of the concerns of involving localized corrosion are discussed. The effects of various parameters, such as temperature and concentration of halide species, on localized corrosion are given. In addition concerns about aging of the protective oxide layer in the expected service temperature range (50 to 250 degrees C) are presented. Also some mechanistic considerations of localized corrosion are given. 31 refs., 1 tab

Self-centering and damping capabilities of a tension-compression device equipped with superelastic NiTi wires

International Nuclear Information System (INIS)

Soul, H; Yawny, A

2015-01-01

The hysteretic damping capacity and high recoverable strains characterizing the superelastic response of shape memory alloys (SMA) make these materials attractive for protection systems of structures subjected to dynamic loads. A successful implementation however is conditioned by functional fatigue exhibited by the SMA when subjected to cyclic loading. The residual deformation upon cycling and the efficiency in material usage are the two most restrictive issues in this sense. In this paper, a device equipped with superelastic NiTi SMA wires and capable of supporting external tension compression loads with optimized properties is presented. It is shown how the introduction of the wires’ pre-straining allows for the absorption of deleterious residual deformation without affecting the self-centering capabilities upon unloading, in contrast with what occurs for pre-strained tendons. These features were experimentally verified in an in-scale prototype composed of two 1.2 mm diameter superelastic NiTi SMA wires. In order to numerically assess the dynamic response of a simple structure subjected to seismic excitations, a multilinear superelasticity model for the NiTi wires was developed. (paper)

Dynamic and cyclic fatigue of engine-driven rotary nickel-titanium endodontic instruments.

Science.gov (United States)

Haïkel, Y; Serfaty, R; Bateman, G; Senger, B; Allemann, C

1999-06-01

The absence of adequate testing standards for engine-driven nickel-titanium (NiTi) instruments necessitates further study of these instruments in all areas. This study examined three groups of engine-driven rotary NiTi endodontic instruments (Profile, Hero, and Quantec) and assessed the times for dynamic fracture in relation to the radius of curvature to which the instruments were subjected during preparation, with the instrument diameter determined by size and taper and the mode by which the fracture occurred. Ten instruments were randomly selected representing each size and taper for each group and for each radius of curvature: 600 in total. The instruments were rotated at 350 rpm and introduced into a tempered steel curve that simulated a canal. Two radii of curvature of canals were used: 5 and 10 mm. Time at fracture was noted for all files, and the fracture faces of each file were analyzed with scanning electron microscopy. Radius of curvature was found to be the most significant factor in determining the fatigue resistance of the files. As radius of curvature decreased, fracture time decreased. Taper of files was found to be significant in determining fracture time. As diameter increased, fracture time decreased. In all cases, fracture was found to be of a ductile nature, thus implicating cyclic fatigue as a major cause of failure and necessitating further analyses and setting of standards in this area.

The influence of distal-end heat treatment on deflection of nickel-titanium archwire

Directory of Open Access Journals (Sweden)

Marcelo Faria da Silva

2016-02-01

Full Text Available Objective: The aim of this in vitro study was to evaluate the deflection-force behavior of nickel-titanium (NiTi orthodontic wires adjacent to the portion submitted to heat treatment. Material and Methods: A total of 106 segments of NiTi wires (0.019 x 0.025-in and heat-activated NiTi wires (0.016 x 0.022-in from four commercial brands were tested. The segments were obtained from 80 archwires. For the experimental group, the distal portion of each segmented archwire was subjected to heat treatment (n = 40, while the other distal portion of the same archwire was used as a heating-free control group (n = 40. Deflection tests were performed in a temperature-controlled universal testing machine. Unpaired Student's t-tests were applied to determine if there were differences between the experimental and control groups for each commercial brand and size of wire. Statistical significance was set at p < 0.05. Results: There were no statistically significant differences between the tested groups with the same size and brand of wire. Conclusions: Heat treatment applied to the distal ends of rectangular NiTi archwires does not permanently change the elastic properties of the adjacent portions.

Influence of Surface Roughness on the Fatigue Life of Nickel-Titanium Rotary Endodontic Instruments.

Science.gov (United States)

Lopes, Hélio P; Elias, Carlos N; Vieira, Márcia V B; Vieira, Victor T L; de Souza, Letícia Chaves; Dos Santos, Alexander Lopes

2016-06-01

The goal of the present study was to evaluate the influence of surface grooves (peaks and valleys) resulting from machining during the manufacturing process of polished and unpolished nickel-titanium BR4C endodontic files on the fatigue life of the instruments. Ten electropolished and 10 unpolished endodontic files were provided by the manufacturer. Specimens were from the same batch, but the unpolished instruments were removed from the production line before surface treatment. The instruments were evaluated with a profilometer to quantify the surface roughness on the working part of the instruments. Then the files were subjected to rotating bending fatigue tests. Analysis with the profilometer showed that surface grooves were deeper on the unpolished instruments compared with their electropolished counterparts. In the rotating bending fatigue test, the mean and standard deviation for the number of cycles until fracture (NCF) were greater for instruments with less pronounced grooves. Student t test revealed significant differences in all tests (P instruments tested; the smaller the groove depth, the greater the NCF. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Evaluation of surface characteristics of rotary nickel-titanium instruments produced by different manufacturing methods.

Science.gov (United States)

Inan, U; Gurel, M

2017-02-01

Instrument fracture is a serious concern in endodontic practice. The aim of this study was to investigate the surface quality of new and used rotary nickel-titanium (NiTi) instruments manufactured by the traditional grinding process and twisting methods. Total 16 instruments of two rotary NiTi systems were used in this study. Eight Twisted Files (TF) (SybronEndo, Orange, CA, USA) and 8 Mtwo (VDW, Munich, Germany) instruments were evaluated. New and used of 4 experimental groups were evaluated using an atomic force microscopy (AFM). New and used instruments were analyzed on 3 points along a 3 mm. section at the tip of the instrument. Quantitative measurements according to the topographical deviations were recorded. The data were statistically analyzed with paired samples t-test and independent samples t-test. Mean root mean square (RMS) values for new and used TF 25.06 files were 10.70 ± 2.80 nm and 21.58 ± 6.42 nm, respectively, and the difference between them was statistically significant (P instruments produced by twisting method (TF 25.06) had better surface quality than the instruments produced by traditional grinding process (Mtwo 25.06 files).

Deflection test evaluation of different lots of the same nickel-titanium wire commercial brand

Directory of Open Access Journals (Sweden)

Murilo Gaby Neves

2016-02-01

Full Text Available Introduction: The aim of this in vitro study was to compare the elastic properties of the load-deflection ratio of orthodontic wires of different lot numbers and the same commercial brand. Methods: A total of 40 nickel-titanium (NiTi wire segments (Morelli OrtodontiaTM - Sorocaba, SP, Brazil, 0.016-in in diameter were used. Groups were sorted according to lot numbers (lots 1, 2, 3 and 4. 28-mm length segments from the straight portion (ends of archwires were used. Deflection tests were performed in an EMIC universal testing machine with 5-N load cell at 1 mm/minute speed. Force at deactivation was recorded at 0.5, 1, 2 and 3 mm deflection. Analysis of variance (ANOVA was used to compare differences between group means. Results: When comparing the force of groups at the same deflection (3, 2 and 1 mm, during deactivation, no statistical differences were found. Conclusion: There are no changes in the elastic properties of different lots of the same commercial brand; thus, the use of different lots of the orthodontic wires used in this research does not compromise the final outcomes of the load-deflection ratio.

Deflection test evaluation of different lots of the same nickel-titanium wire commercial brand.

Science.gov (United States)

Neves, Murilo Gaby; Lima, Fabrício Viana Pereira; Gurgel, Júlio de Araújo; Pinzan-Vercelino, Célia Regina Maio; Rezende, Fernanda Soares; Brandão, Gustavo Antônio Martins

2016-01-01

The aim of this in vitro study was to compare the elastic properties of the load-deflection ratio of orthodontic wires of different lot numbers and the same commercial brand. A total of 40 nickel-titanium (NiTi) wire segments (Morelli Ortodontia™--Sorocaba, SP, Brazil), 0.016-in in diameter were used. Groups were sorted according to lot numbers (lots 1, 2, 3 and 4). 28-mm length segments from the straight portion (ends) of archwires were used. Deflection tests were performed in an EMIC universal testing machine with 5-N load cell at 1 mm/minute speed. Force at deactivation was recorded at 0.5, 1, 2 and 3 mm deflection. Analysis of variance (ANOVA) was used to compare differences between group means. When comparing the force of groups at the same deflection (3, 2 and 1 mm), during deactivation, no statistical differences were found. There are no changes in the elastic properties of different lots of the same commercial brand; thus, the use of different lots of the orthodontic wires used in this research does not compromise the final outcomes of the load-deflection ratio.

Inorganic ion exchanger based on tin/titanium mixed oxide doped with europium to be used in radioactive waste

International Nuclear Information System (INIS)

Paganini, Paula P.; Felinto, Maria Claudia F.C.; Kodaira, Claudia A.; Brito, Hermi F.

2009-01-01

This work presents the results of synthesis and characterization of an inorganic ion exchanger based on tin/titanium mixed oxides doped with europium (SnO 2 /TiO 2 :Eu 3+ ) to be used in environmental field. The adsorption study of nickel was realized in this exchanger to recover the nickel metal which is in thorium-nickel alloys used as electrode of discharge lamps. The studied exchanger was synthesized by neutralization of tin chloride (IV) and titanium chloride (III) mixed solution and characterized by thermogravimetric measurement (TG), Differential Scanning Calorimetry (DSC), X-Ray Powder Diffraction (XRD), Infrared Spectroscopy (IR) and Scanning Electron Microscopy (SEM). The adsorption study showed that these inorganic ion exchangers are good materials to recovery nickel with high weight distribution ratios (Dw Ni 2+ ) and percent adsorption. (author)

Numerical simulation of the force generated by a superelastic NiTi orthodontic archwire during tooth alignment phase: comparison between different constitutive models

Science.gov (United States)

Gannoun, M.; Laroussi Hellara, M.; Bouby, C.; Ben Zineb, T.; Bouraoui, T.

2018-04-01

Nickel Titanium (NiTi) Superelastic (SE) Shape Memory Alloys (SMAs) are widely considered for applications that need high reversible strain or high recovery forces. In particular, the SE SMAs present a high interest for biomedical applications such as endodontic and orthodontic apparatus. They are available in a large variety of archwires exerting continuum forces to ensure the dental displacement. The purpose of this study is to report the clinical implications of NiTi SE wires for dental treatment in a given configuration. Three main constitutive models of the literature (Lagoudas and Boyd 1996 Int. J. Plast. 12 805–842, Auricchio and Petrini 2004 Int. J. Numer. Meth. Engng. 61 807–836 and Chemisky et al 2011 Mech. Mater. 68 361–376) are considered for the finite element (FE) numerical simulations of the SMA archwires response. Tensile tests had been carried out in order to identify the material parameters of these constitutive models. The FE numerical study allowed to predict the dental displacement and its corresponding orthodontic force level exerted by the wire in similar conditions to those in the oral environment. This work allows to predict the orthodontic generated load by a NiTi SE archwire with a 0.64 × 0.46 mm2 rectangular cross section under prescribed thermomechanical conditions. The effect of the temperature and the alveolar bone stiffness on the orthodontic load level and the tooth displacement degree has been investigated. The performed numerical simulations demonstrate that the orthodontic load is sensitive to the displacement magnitude, to the tooth stiffness and to the temperature variations. The obtained forces applied continuously and at a constant level are within the acceptable orthodontic force level range. Some directives are therefore provided to help orthodontists to select the optimal archwire.

Corrosion of titanium alloys in concentrated chloride solutions at temperature up to 160 deg C

International Nuclear Information System (INIS)

Ruskol, Yu.S.; Viter, L.I.; Balakin, A.I.; Fokin, M.N.

1982-01-01

Resistance of VT1-0 titanium and 4200, 4207 titanium alloys to pitting and total corrosion in chlorides of cadmium, potassium, nickel, ammonium, barium, calcium, lithium, magnesium in respect to pH value and temperature (120,140,160 deg C) is determined. The results obtained are presented as nomograms of stability. Possible reasons for corrosion behaviour of titanium in each of the chlorides are discussed

Study on mechanics of driving drum with superelastic convexity surface covering-layer structure

Energy Technology Data Exchange (ETDEWEB)

Xiao, L.J.; Sui, X.H.; Miao, D.J. [Shandong University of Science & Technology, Qingdao (China)

2008-09-15

Belt conveyor is one of the main transport equipment in coal mine and the driving drum is its key part. With the method of bionic design, the mushroom morphological structure is applied to the design of covering-layer structure of driving drum surface of belt conveyor. Superelastic rubber with large deformation is adopted as the covering-layer material. Nonlinear constitutive model of rubber, which is of superelasticity and large deformation, is established. The stress states and deformation principles of driving drums including both bionic covering-layer and common covering-layer are obtained by static intensity analysis with Finite Element Analysis (FEA) software ANSYS. The values of the stress and strain on the driving drum surface are gotten and the dangerous area is determined. FEA results show that the superelastic convexity surface structure can enlarge the contact area between the driving drum and viscoelastic belt. The results also show that in comparison with common driving drum, the bionic surface driving drum can not only increase the friction coefficient between drum and belt but also prolong its service life.

Superelastic stress-strain behavior in ferrogels with different types of magneto-elastic coupling

Science.gov (United States)

Cremer, Peet; Löwen, Hartmut; Menzel, Andreas M.

Colloidal magnetic particles embedded in an elastic polymer matrix constitute a smart material called ferrogel. It responds to an applied external magnetic field by changes in elastic properties, which can be exploited for various applications like dampers, vibration absorbers, or actuators. Under appropriate conditions, the stress-strain behavior of a ferrogel can display a fascinating feature: superelasticity, the capability to reversibly deform by a huge amount while barely altering the applied load. In a previous work, using numerical simulations, we investigated this behavior assuming that the magnetic moments carried by the embedded particles can freely reorient to minimize their magnetic interaction energy. Here, we extend the analysis to ferrogels where restoring torques by the surrounding matrix hinder rotations towards a magnetically favored configuration. For example, the particles can be chemically cross-linked into the polymer matrix and the magnetic moments can be fixed to the particle axes. We demonstrate that these systems still feature a superelastic regime. As before, the nonlinear stress-strain behavior can be reversibly tailored during operation by external magnetic fields. Yet, the different coupling of the magnetic moments causes different types of response to external stimuli. For instance, an external magnetic field applied parallel to the stretching axis hardly affects the superelastic regime but stiffens the system beyond it. Other smart materials featuring superelasticity, e.g. metallic shape-memory alloys, have already found widespread applications. Our soft polymer systems offer many additional advantages like a typically higher deformability and enhanced biocompatibility combined with high tunability.

Effect of nitrogen addition and annealing temperature on superelastic properties of Ti-Nb-Zr-Ta alloys

Energy Technology Data Exchange (ETDEWEB)

Tahara, Masaki [Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Kim, Hee Young, E-mail: heeykim@ims.tsukuba.ac.jp [Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Hosoda, Hideki [Precision and Intelligence Laboratory, Tokyo Institute of Technology, Yokohama 226-8503 (Japan); Nam, Tae-hyun [School of Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processingnd ERI, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of); Miyazaki, Shuichi, E-mail: miyazaki@ims.tsukuba.ac.jp [Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); School of Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processingnd ERI, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of)

2010-10-15

Research highlights: In this study, the effects of composition and annealing temperature on microstructure, shape memory effect and superelastic properties were investigated in Ti-Nb-4Zr-2Ta-N alloys by measuring stress-strain curves at various temperatures and using transmission electron microscopy. Dissolution of {alpha} phase increases M{sub s} and decreases the critical stress for slip for the Ti-22Nb-4Zr-2Ta alloy while it causes the decrease of M{sub s} and the increase of the critical stress for slip for the Ti-20Nb-4Zr-2Ta-0.6N alloy. The different effect of dissolution of {alpha} phase can be attributed to the fact that N is absorbed in {alpha} phase. - Abstract: The composition dependence of the mechanical properties and martensitic transformation behavior of Ti-Nb-4Zr-2Ta-N alloys is investigated. The effect of annealing temperature on the microstructural evolution and superelastic properties in the N-added and N-free alloys is compared. The addition of N decreases M{sub s} of Ti-Nb-4Zr-2Ta alloys by about 200 K per 1 at.%N and improves the superelastic properties of Ti-Nb-4Zr-2Ta alloys. The dissolution of {alpha} phase increases the martensitic transformation start temperature and decreases the superelastic recovery strain for the N-free alloy, whereas it causes opposite effects for the N-added alloy. The different annealing temperature dependences of superelastic properties are discussed on the basis of microstructure observation.

Effect of nitrogen addition and annealing temperature on superelastic properties of Ti-Nb-Zr-Ta alloys

International Nuclear Information System (INIS)

Tahara, Masaki; Kim, Hee Young; Hosoda, Hideki; Nam, Tae-hyun; Miyazaki, Shuichi

2010-01-01

Research highlights: In this study, the effects of composition and annealing temperature on microstructure, shape memory effect and superelastic properties were investigated in Ti-Nb-4Zr-2Ta-N alloys by measuring stress-strain curves at various temperatures and using transmission electron microscopy. Dissolution of α phase increases M s and decreases the critical stress for slip for the Ti-22Nb-4Zr-2Ta alloy while it causes the decrease of M s and the increase of the critical stress for slip for the Ti-20Nb-4Zr-2Ta-0.6N alloy. The different effect of dissolution of α phase can be attributed to the fact that N is absorbed in α phase. - Abstract: The composition dependence of the mechanical properties and martensitic transformation behavior of Ti-Nb-4Zr-2Ta-N alloys is investigated. The effect of annealing temperature on the microstructural evolution and superelastic properties in the N-added and N-free alloys is compared. The addition of N decreases M s of Ti-Nb-4Zr-2Ta alloys by about 200 K per 1 at.%N and improves the superelastic properties of Ti-Nb-4Zr-2Ta alloys. The dissolution of α phase increases the martensitic transformation start temperature and decreases the superelastic recovery strain for the N-free alloy, whereas it causes opposite effects for the N-added alloy. The different annealing temperature dependences of superelastic properties are discussed on the basis of microstructure observation.

Repercussion of noni mouthwash on surface characterization of Nickel-Titanium archwire

Directory of Open Access Journals (Sweden)

Dhivya Dilipkumar

2017-01-01

Full Text Available Objective: Maintaining oral hygiene is very important during orthodontic therapy mouthwashes are prescribed as an adjunct to improve patient's oral hygiene. Commercially available mouthwashes e.g. Chlorhexidine, Listerine, fluoride containing mouthwashes have shown to alter the surface characteristics of orthodontic wires. Hence the purpose of the study was to evaluate the effect of Noni mouthwash on surface quality and compositional changes of Nickel Titanium orthodontic wires. Materials and Methods: In this in vitro study pre-formed 0.014 inch NiTi arch wire was used. The study comprised of two samples, one control and one test sample which were 25mm in length. Control sample was stored at room temperature without any manipulation while test sample was immersed in Noni mouthwash solution for 1.5 hours, after which the test specimen was removed from the mouthwash solution and rinsed with distilled water. Both control and test samples were sent for scanning electron microscopy analysis, to qualitatively characterize the topography of the wire surface. Electron dispersion spectrum analysis was done to evaluate the various components of both the wires. Results: No significant difference in the average surface roughness for both wire samples was observed. There was no significant difference seen in the composition of wire after immersion in Noni mouthwash. Conclusion: Noni mouthwash did not have significant influence on the surface roughness or altered the composition of the Ni-Ti wire. Hence Noni mouthwash may be prescribed as a natural, non-destructive prophylactic agent for orthodontic patients.

Effect of coating on properties of esthetic orthodontic nickel-titanium wires.

Science.gov (United States)

Iijima, Masahiro; Muguruma, Takeshi; Brantley, William; Choe, Han-Cheol; Nakagaki, Susumu; Alapati, Satish B; Mizoguchi, Itaru

2012-03-01

To determine the effect of coating on the properties of two esthetic orthodontic nickel-titanium wires. Woowa (polymer coating; Dany Harvest) and BioForce High Aesthetic Archwire (metal coating; Dentsply GAC) with cross-section dimensions of 0.016 × 0.022 inches were selected. Noncoated posterior regions of the anterior-coated Woowa and uncoated Sentalloy were used for comparison. Nominal coating compositions were determined by x-ray fluorescence (JSX-3200, JOEL). Cross-sectioned and external surfaces were observed with a scanning electron microscope (SEM; SSX-550, Shimadzu) and an atomic force microscope (SPM-9500J2, Shimadzu). A three-point bending test (12-mm span) was carried out using a universal testing machine (EZ Test, Shimadzu). Hardness and elastic modulus of external and cross-sectioned surfaces were obtained by nanoindentation (ENT-1100a, Elionix; n  =  10). Coatings on Woowa and BioForce High Aesthetic Archwire contained 41% silver and 14% gold, respectively. The coating thickness on Woowa was approximately 10 µm, and the coating thickness on BioForce High Aesthetic Archwire was much smaller. The surfaces of both coated wires were rougher than the noncoated wires. Woowa showed a higher mean unloading force than the noncoated Woowa, although BioForce High Aesthetic Archwire showed a lower mean unloading force than Sentalloy. While cross-sectional surfaces of all wires had similar hardness and elastic modulus, values for the external surface of Woowa were smaller than for the other wires. The coating processes for Woowa and BioForce High Aesthetic Archwire influence bending behavior and surface morphology.

Estimation of changes in nickel and chromium content in nickel-titanium and stainless steel orthodontic wires used during orthodontic treatment: An analytical and scanning electron microscopic study

Directory of Open Access Journals (Sweden)

Vandana Kararia

2015-01-01

Full Text Available Introduction: The biocompatibility of orthodontic dental alloys has been investigated over the past 20 years, but the results have been inconclusive. The study compares standard 3 M Unitek nickel-titanium (NiTi and stainless steel archwires with locally available JJ orthodontics wires. Scanning electron microscope (SEM study of surface changes and complexometric titration to study compositional change was performed. Materials and Methods: Ten archwires each of group 1-3 M 0.016" NiTi, group 2-JJ 0.016" NiTi, group 3-3 M 0.019" FNx010.025" SS and group 4-JJ SS contributed a 10 mm piece of wire for analysis prior to insertion in the patient and 6 weeks post insertion. SEM images were recorded at Χ2000, Χ4000 and Χ6000 magnification. The same samples were subjected to complexiometric titration using ethylenediaminetetraacetic acid to gauge the actual change in the composition. Observations and Results: The SEM images of all the archwires showed marked changes with deep scratches and grooves and dark pitting corrosion areas post intraoral use. 3M wires showed an uniform criss-cross pattern in as received wires indicating a coating which was absent after intraoral use. There was a significant release of Nickel and Chromium from both group 3 and 4. Group 2 wires released ions significantly more than group 1 (P = 0.0. Conclusion: Extensive and stringent trials are required before certifying any product to be used in Orthodontics.

Effects of electropolishing surface treatment on the cyclic fatigue resistance of BioRace nickel-titanium rotary instruments.

Science.gov (United States)

Lopes, Hélio P; Elias, Carlos N; Vieira, Victor T L; Moreira, Edson J L; Marques, Raquel V L; de Oliveira, Julio C Machado; Debelian, Gilberto; Siqueira, José F

2010-10-01

This study evaluated the influence of electropolishing surface treatment on the number of cycles to fracture of BioRace rotary nickel-titanium endodontic instruments. BioRace size BR5C instruments with or without electropolishing surface treatment were used in an artificial curved canal under rotational speed of 300 rpm until fracture. Fractured surfaces and the helical shafts of fractured instruments were analyzed by scanning electron microscopy (SEM). Polished instruments displayed a significantly higher number of cycles to fracture when compared with nonpolished instruments (P ductile morphologic characteristics. Evaluation of the separated fragments after cyclic fatigue testing showed the presence of microcracks near the fracture surface. Polished instruments exhibited fine cracks that assumed an irregular path (zigzag crack pattern), whereas nonpolished instruments showed cracks running along the machining grooves. Electropolishing surface treatment of BioRace endodontic instruments significantly increased the cyclic fatigue resistance. Copyright © 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Effect of nitriding surface treatment on the corrosion resistance of dental nickel-titanium files in 5.25% sodium hypochlorite solution

Energy Technology Data Exchange (ETDEWEB)

Liu, J.-F. [Department of Dentistry, National Yang-Ming University, Taipei, Taiwan (China); Department of Dentistry, Taichung Veterans General Hospital, Taichung, Taiwan (China); Lin, M.-C. [Department of Dentistry, National Yang-Ming University, Taipei, Taiwan (China); Department of Dental Laboratory Technology, Central Taiwan University of Science and Technology, Taichung, Taiwan (China); Hsu, M.-L. [Department of Dentistry, National Yang-Ming University, Taipei, Taiwan (China); Li, U.-M. [Dental Department, Cardinal Tien Hospital, Hsintien, Taiwan (China); Lin, C.-P. [Department of Dentistry, National Taiwan University, Taipei, Taiwan (China); Tsai, W.-F.; Ai, C.-F. [Institute of Nuclear Energy Research, Atomic Energy Council, Taoyuan, Taiwan (China); Chen, L.-K. [Department of Dentistry, Taipei City Hospital, Taipei, Taiwan (China); Huang, H.-H. [Department of Dentistry, National Yang-Ming University, Taipei, Taiwan (China); Department of Dentistry, Taipei City Hospital, Taipei, Taiwan (China); Institute of Oral Biology, National Yang-Ming University, Taipei, Taiwan (China)], E-mail: hhhuang@ym.edu.tw

2009-05-05

This study investigated the effect of nitriding surface treatment on the corrosion resistance of commercial dental alloy, in the form of helical nickel-titanium (Ni-Ti) files, when treated with 5.25% sodium hypochlorite (NaOCl) solution. The surface of dental helical Ni-Ti files was modified using nitriding treatment at 200 deg. C, 250 deg. C and 300 deg. C in an NH{sub 3}-containing environment. The surface morphology and chemical composition of the Ni-Ti files were analyzed using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The corrosion resistance of the Ni-Ti files when treated with a clinical solution of 5.25% NaOCl was evaluated using the linear polarization method and by potentiodynamic polarization curve measurement. The nitriding treatments at different temperatures created titanium nitride (TiN) on the surface of the helical Ni-Ti files. The Ni-Ti files nitrided at 200 deg. C and 250 deg. C showed higher polarization resistance and higher passive film breakdown potential together with a lower passive current than untreated files. The presence of TiN on dental Ni-Ti files significantly increased the corrosion resistance of the files in the presence of 5.25% NaOCl solution.

Effect of nitriding surface treatment on the corrosion resistance of dental nickel-titanium files in 5.25% sodium hypochlorite solution

International Nuclear Information System (INIS)

Liu, J.-F.; Lin, M.-C.; Hsu, M.-L.; Li, U.-M.; Lin, C.-P.; Tsai, W.-F.; Ai, C.-F.; Chen, L.-K.; Huang, H.-H.

2009-01-01

This study investigated the effect of nitriding surface treatment on the corrosion resistance of commercial dental alloy, in the form of helical nickel-titanium (Ni-Ti) files, when treated with 5.25% sodium hypochlorite (NaOCl) solution. The surface of dental helical Ni-Ti files was modified using nitriding treatment at 200 deg. C, 250 deg. C and 300 deg. C in an NH 3 -containing environment. The surface morphology and chemical composition of the Ni-Ti files were analyzed using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The corrosion resistance of the Ni-Ti files when treated with a clinical solution of 5.25% NaOCl was evaluated using the linear polarization method and by potentiodynamic polarization curve measurement. The nitriding treatments at different temperatures created titanium nitride (TiN) on the surface of the helical Ni-Ti files. The Ni-Ti files nitrided at 200 deg. C and 250 deg. C showed higher polarization resistance and higher passive film breakdown potential together with a lower passive current than untreated files. The presence of TiN on dental Ni-Ti files significantly increased the corrosion resistance of the files in the presence of 5.25% NaOCl solution.

Shaping ability of NT Engine and McXim rotary nickel-titanium instruments in simulated root canals. Part 1.

Science.gov (United States)

Thompson, S A; Dummer, P M

1997-07-01

The aim of this study was to determine the shaping ability of NT Engine and McXim nickel-titanium rotary instruments in simulated root canals. In all, 40 canals consisting of four different shapes in terms of angle and position of curvature were prepared by a combination of NT Engine and McXim instruments using the technique recommended by the manufacturer. Part 1 of this two-part report describes the efficacy of the instruments in terms of preparation time, instrument failure, canal blockages, loss of canal length and three-dimensional canal form. Overall, the mean preparation time for all canals was 6.01 min, with canal shape having a significant effect (P Engine and McXim instruments prepared canals rapidly, with few deformations, no canal blockages and with minimal change in working length. The three-dimensional form of the canals demonstrated good flow and taper characteristics.

Numerical simulation of superelastic shape memory alloys subjected to dynamic loads

International Nuclear Information System (INIS)

Cismaşiu, Corneliu; Amarante dos Santos, Filipe P

2008-01-01

Superelasticity, a unique property of shape memory alloys (SMAs), allows the material to recover after withstanding large deformations. This recovery takes place without any residual strains, while dissipating a considerable amount of energy. This property makes SMAs particularly suitable for applications in vibration control devices. Numerical models, calibrated with experimental laboratory tests from the literature, are used to investigate the dynamic response of three vibration control devices, built up of austenitic superelastic wires. The energy dissipation and re-centering capabilities, important features of these devices, are clearly illustrated by the numerical tests. Their sensitivity to ambient temperature and strain rate is also addressed. Finally, one of these devices is tested as a seismic passive vibration control system in a simplified numerical model of a railway viaduct, subjected to different ground accelerations

Force level of small diameter nickel-titanium orthodontic wires ligated with different methods

Directory of Open Access Journals (Sweden)

Rodrigo Hitoshi Higa

2017-08-01

Full Text Available Abstract Background The aim of this study was to compare the deflection force in conventional and thermally activated nickel-titanium (NiTi wires in passive (Damon Q and active (Bioquick self-ligating brackets (SLB and in conventional brackets (CB tied by two different methods: elastomeric ligature (EL and metal ligature (ML. Methods Two wire diameters (0.014 and 0.016 in. and 10 specimens per group were used. The specimens were assembled in a clinical simulation device and tested in an Instron Universal Testing Machine, with a load cell of 10 N. For the testing procedures, the acrylic block representative of the right maxillary central incisor was palatally moved, with readings of the force at 0.5, 1, 2, and 3 mm, at a constant speed of 2 mm/min and temperature of 36.5 °C. Results The conventional NiTi released higher forces than the thermally activated NiTi archwires in large deflections. In general, the SLB showed lower forces, while the ML had higher forces, with both showing a similar force release behavior, constantly decreasing as the deflection decreased. The EL showed an irregular behavior. The active SLB showed smaller forces than passive, in large deflections. Conclusions The SLB and the ML exhibit standard force patterns during unloading, while the elastomeric ligatures exhibit a randomly distributed force release behavior.

Fatigue of orthodontic nickel-titanium (NiTi) wires in different fluids under constant mechanical stress

International Nuclear Information System (INIS)

Prymak, O.; Klocke, A.; Kahl-Nieke, B.; Epple, M.

2003-01-01

The aim of this study was to analyze in vitro the fatigue resistance of nickel-titanium (NiTi) and CuNiTi orthodontic wires when subjected to forces and fluids which are present intraorally. The wires were subjected to dynamic mechanical analysis (DMA) while they were immersed into different fluids with mechanical loading parameters similar to those that are subjected in the mouth. The characteristic temperatures of transitions and a rough surface structure on the perimeter of the wires were determined by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), respectively, before and after the DMA experiments. Stainless steel wires were used for comparison. In general, NiTi wires fractured earlier than the stainless steel specimens. Survival times were lower for the NiTi wires when immersed in fluids (water, citric acid, NaCl solution, artificial saliva, and fluoridated artificial saliva) than in air. SEM surface analysis showed that the NiTi and CuNiTi wires had a rougher surface than steel wires. The fracture occurred within a short number of loading cycles. Until fracture occurred, the mechanical properties remained mostly constant

Fatigue of orthodontic nickel-titanium (NiTi) wires in different fluids under constant mechanical stress

Energy Technology Data Exchange (ETDEWEB)

Prymak, O.; Klocke, A.; Kahl-Nieke, B.; Epple, M

2003-07-25

The aim of this study was to analyze in vitro the fatigue resistance of nickel-titanium (NiTi) and CuNiTi orthodontic wires when subjected to forces and fluids which are present intraorally. The wires were subjected to dynamic mechanical analysis (DMA) while they were immersed into different fluids with mechanical loading parameters similar to those that are subjected in the mouth. The characteristic temperatures of transitions and a rough surface structure on the perimeter of the wires were determined by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), respectively, before and after the DMA experiments. Stainless steel wires were used for comparison. In general, NiTi wires fractured earlier than the stainless steel specimens. Survival times were lower for the NiTi wires when immersed in fluids (water, citric acid, NaCl solution, artificial saliva, and fluoridated artificial saliva) than in air. SEM surface analysis showed that the NiTi and CuNiTi wires had a rougher surface than steel wires. The fracture occurred within a short number of loading cycles. Until fracture occurred, the mechanical properties remained mostly constant.

'In situ' and 'Post-mortem' TEM study of the super-elastic effect in Cu-Al-Ni shape memory alloys

International Nuclear Information System (INIS)

Ibarra, A.; San Juan, J.; Bocanegra, E.H.; Caillard, D.; No, M.L.

2006-01-01

An analysis of the microstructure evolution during super-elastic cycling has been performed by transmission electron microscopy (TEM) in order to understand the physical mechanism responsible for the thermo-mechanical properties evolution, as well as the martensitic transformation ageing. Particularly, in this work we have studied the super-elastic effect in Cu-Al-Ni shape memory alloys by 'in situ' TEM experiments. The bright field images and diffraction patterns have allowed us to determine, during the transformation, the kind of nucleated martensite variants and their relative orientations. Finally, we have analysed the super-elastic effect on the dislocation microstructure and on the transformation temperatures

On superplasticity of corrosion resistant ferritic-austenitic chromium-nickel steels

Energy Technology Data Exchange (ETDEWEB)

Surovtsev, A P; Sukhanov, V E

1988-01-01

The deformability of corrosion resistant chromium-nickel ferritic austenitic steel type O8Kh22N6T under tension, upsetting and torsion in the 600-1200 deg C temperature range is studied. For the deformation rate of the order of 10/sup -3/ s/sup -1/ the effect of superelasticity reveals itself at 850 deg C in the process of ferrite dynamic polymerization, in the 925-950 deg C range, at initial stages of dynamic recrystallization - the dynamic polygonization controlled by chromium carbide dissolving in steel and maximum at 1050 deg C in the process of development of austenite dynamic recrystallization with grain refinement with F/A ratio equalling 1. After upsetting in the elasticity mode at 1050 deg C the impact strength of the above steel is maximum.

Combining thermodynamic principles with Preisach models for superelastic shape memory alloy wires

International Nuclear Information System (INIS)

Doraiswamy, S; Rao, A; Srinivasa, A R

2011-01-01

We present a simple model for simulating the response of a superelastic shape memory alloy wire based on the thermodynamics of irreversible processes, which can simulate the full thermomechanical response including internal hysteresis loops, at different temperatures, with minimal data input. The key idea is to separate the dissipative response and the elastic response of shape memory alloys using a Gibbs potential based formulation, and then use a Preisach model for the dissipative part of the response. This enables better handling of the features observed in the superelastic response such as those due to changes in temperature and internal hysteresis loops. We compare the predicted response with experiments performed on 0.75 mm NiTi shape memory alloy wires at three different temperatures

Nickel films: Nonselective and selective photochemical deposition and properties

International Nuclear Information System (INIS)

Smirnova, N.V.; Boitsova, T.B.; Gorbunova, V.V.; Alekseeva, L.V.; Pronin, V.P.; Kon'uhov, G.S.

2006-01-01

Nickel films deposited on quartz surfaces by the photochemical reduction of a chemical nickel plating solution were studied. It was found that the deposition of the films occurs after an induction period, the length of which depends on the composition of the photolyte and the light intensity. Ni particles with a mean diameter of 20-30 nm were detected initially by transmission electron microscopy. The particles then increased in size (50 nm) upon irradiation and grouped into rings consisting of 4-5 particles. Irradiation with high-intensity light produces three-dimensional films. The calculated extinction coefficient of the nickel film was found to be 4800 L mol -1 cm -1 . Electron diffraction revealed that the prepared amorphous nickel films crystallize after one day of storage. It was determined that the films exhibit catalytic activity in the process of nickel deposition from nickel plating solution. The catalytic action remains for about 5-7 min after exposure of the films to air. The processes of selective and nonselective deposition of the nickel films are discussed. The use of poly(butoxy titanium) in the process of selective photochemical deposition enables negative and positive images to be prepared on quartz surfaces

Impact of a nickel-reduced stainless steel implant on striated muscle microcirculation: a comparative in vivo study.

Science.gov (United States)

Kraft, C N; Burian, B; Perlick, L; Wimmer, M A; Wallny, T; Schmitt, O; Diedrich, O

2001-12-05

The impairment of skeletal muscle microcirculation by a biomaterial may have profound consequences. With moderately good physical and corrosion characteristics, implant-quality stainless steel is particularly popular in orthopedic surgery. However, due to the presence of a considerable amount of nickel in the alloy, concern has been voiced in respect to local tissue responses. More recently a stainless steel alloy with a significant reduction of nickel has become commercially available. We, therefore, studied in vivo nutritive perfusion and leukocytic response of striated muscle to this nickel-reduced alloy, and compared these results with those of the materials conventional stainless steel and titanium. Using the hamster dorsal skinfold chamber preparation and intravital microscopy, we could demonstrate that reduction of the nickel quantity in a stainless steel implant has a positive effect on local microvascular parameters. Although the implantation of a conventional stainless steel sample led to a distinct and persistent activation of leukocytes combined with disruption of the microvascular endothelial integrity, marked leukocyte extravasation, and considerable venular dilation, animals with a nickel-reduced stainless steel implant showed only a moderate increase of these parameters, with a clear tendency of recuperation. Titanium implants merely caused a transient increase of leukocyte-endothelial cell interaction within the first 120 min, and no significant change in macromolecular leakage, leukocyte extravasation, or venular diameter. Pending biomechanical and corrosion testing, nickel-reduced stainless steel may be a viable alternative to conventional implant-quality stainless steel for biomedical applications. Concerning tolerance by the local vascular system, titanium currently remains unsurpassed. Copyright 2001 John Wiley & Sons, Inc. J Biomed Mater Res 57: 404-412, 2001

Rapid, Reliable Shape Setting of Superelastic Nitinol for Prototyping Robots.

Science.gov (United States)

Gilbert, Hunter B; Webster, Robert J

Shape setting Nitinol tubes and wires in a typical laboratory setting for use in superelastic robots is challenging. Obtaining samples that remain superelastic and exhibit desired precurvatures currently requires many iterations, which is time consuming and consumes a substantial amount of Nitinol. To provide a more accurate and reliable method of shape setting, in this paper we propose an electrical technique that uses Joule heating to attain the necessary shape setting temperatures. The resulting high power heating prevents unintended aging of the material and yields consistent and accurate results for the rapid creation of prototypes. We present a complete algorithm and system together with an experimental analysis of temperature regulation. We experimentally validate the approach on Nitinol tubes that are shape set into planar curves. We also demonstrate the feasibility of creating general space curves by shape setting a helical tube. The system demonstrates a mean absolute temperature error of 10°C.

Tensile and superelastic fatigue characterization of NiTi shape memory cables

Science.gov (United States)

Sherif, Muhammad M.; Ozbulut, Osman E.

2018-01-01

This paper discusses the tensile response and functional fatigue characteristics of a NiTi shape memory alloy (SMA) cable with an outer diameter of 5.5 mm. The cable composed of multiple strands arranged as one inner core and two outer layers. The results of the tensile tests revealed that the SMA cable exhibits good superelastic behavior up to 10% strain. Fatigue characteristics were investigated under strain amplitudes ranging from 3% to 7% and a minimum of 2500 loading cycles. The evolutions of maximum tensile stress, residual strains, energy dissipation, and equivalent viscous damping under a number of loading cycles were analyzed. The fracture surface of a specimen subjected to 5000 loading cycles and 7% strain was discussed. Functional fatigue test results indicated a very high superelastic fatigue life cycle for the tested NiTi SMA cable.

Superelasticity, corrosion resistance and biocompatibility of the Ti–19Zr–10Nb–1Fe alloy

Energy Technology Data Exchange (ETDEWEB)

Xue, Pengfei [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University, Beijing 100191 (China); Li, Yan, E-mail: liyan@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University, Beijing 100191 (China); Li, Kangming [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University, Beijing 100191 (China); Zhang, Deyuan [Life Tech Scientific Corporation, Shenzhen 518057 (China); Zhou, Chungen [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

2015-05-01

Microstructure, mechanical properties, superelasticity and biocompatibility of a Ti–19Zr–10Nb–1Fe alloy are investigated. X-ray diffraction spectroscopy and transmission electron microscopy observations show that the as-cast Ti–19Zr–10Nb–1Fe alloy is composed of α′ and β phases, but only the β phase exists in the as-rolled and as-quenched alloys. The tensile stress–strain tests indicate that the as-quenched alloy exhibits a good combination of mechanical properties with a large elongation of 25%, a low Young's modulus of 59 GPa and a high ultimate tensile stress of 723 MPa. Superelastic recovery behavior is found in the as-quenched alloy during tensile tests, and the corresponding maximum of superelastic strain is 4.7% at the pre-strain of 6%. A superelastic recovery of 4% with high stability is achieved after 10 cyclic loading–unloading training processes. Potentiodynamic polarization and ion release measurements indicate that the as-quenched alloy shows a lower corrosion rate in Hank's solution and a much less ion release rate in 0.9% NaCl solution than those of the NiTi alloys. Cell culture results indicate that the osteoblasts' adhesion and proliferation are similar on both the Ti–19Zr–10Nb–1Fe and NiTi alloys. A better hemocompatibility is confirmed for the as-quenched Ti–19Zr–10Nb–1Fe alloy, attributed to more stable platelet adhesion and small activation degree, and a much lower hemolysis rate compared with the NiTi alloy. - Highlights: • A stable superelastic strain of 4.0% is achieved for the Ti–19Zr–10Nb–1Fe alloy. • The ion release rates of Ti–19Zr–10Nb–1Fe are much lower than that of Ni in NiTi. • Ti–19Zr–10Nb–1Fe has a similar cytocompatibility compared with the NiTi alloy. • Ti–19Zr–10Nb–1Fe exhibits a better hemocompatibility than the NiTi alloy.

Synthesis of p-type nickel oxide nanosheets on n-type titanium dioxide nanorod arrays for p-n heterojunction-based UV photosensor

Science.gov (United States)

Yusoff, M. M.; Mamat, M. H.; Malek, M. F.; Abdullah, M. A. R.; Ismail, A. S.; Saidi, S. A.; Mohamed, R.; Suriani, A. B.; Khusaimi, Z.; Rusop, M.

2018-05-01

Titanium dioxide (TiO2) nanorod arrays (TNAs) were synthesized and deposited on fluorine tin oxide (FTO)-coated glass substrate using a novel and facile immersion method in a glass container. The synthesis and deposition of p-type nickel oxide (NiO) nanosheets (NS) on the n-type TNAs was investigated in the p-n heterojunction photodiode (PD) for the application of ultraviolet (UV) photosensor. The fabricated TNAs/NiO NS based UV photosensor exhibited a highly increased photocurrent of 4.3 µA under UV radiation (365 nm, 750 µW/cm2) at 1.0 V reverse bias. In this study, the fabricated TNAs/NiO NS p-n heterojunction based photodiode showed potential applications for UV photosensor based on the stable photo-generated current attained under UV radiation.

Load carrying capacity of RCC beams by replacing steel reinforcement bars with shape memory alloy bars

Science.gov (United States)

Bajoria, Kamal M.; Kaduskar, Shreya S.

2016-04-01

In this paper the structural behavior of reinforced concrete (RC) beams with smart rebars under two point loading system has been numerically studied, using Finite Element Method. The material used in this study is Super-elastic Shape Memory Alloys (SE SMAs) which contains nickel and titanium. In this study, different quantities of steel and SMA rebars have been used for reinforcement and the behavior of these models under two point bending loading system is studied. A comparison of load carrying capacity for the model between steel reinforced concrete beam and the beam reinforced with S.M.A and steel are performed. The results show that RC beams reinforced with combination of shape memory alloy and steel show better performance.

The characteristics of corrosion, radiation degradation and dissolution of titanium alloys

International Nuclear Information System (INIS)

Sung, K. W.; Na, J. W.; Choi, B. S.; Lee, D. J.; Chang, M. H.

2001-12-01

In order to establish the technical bases of water chemistry design requirement related titanium alloys, we investigated the characteristics of corrosion, activation, radiation degradation, radiation hydrogen embrittlement of titanium alloys and dissolution of titanium dioxide. Titanium alloys generally have high corrosion resistance. Corrosion product release from PT-7M and PT-3V titanium alloy surface for 18 months of operation is negligible, and the corrosion penetration for about 30 years is about 1 μm, while the corrosion rates is not higher than one third of that of austenitic steel. Titanium only converts into Sc-46 with 85 day halflife after neutron irradiation, and its radioactivity is not higher than one thousandth of that produced from nickel. Therefore, under the condition without any neutron irradiation, the radiation damage of titanium alloys would have no problem. Titanium dioxide, that protects the metals from the corrosion, has retrograde solubility in neutral solutions. It does not form any complexes with ligands such as ammonia, but Ti(IV) gets more stable by complexing with water molecules. In conclusion, it is estimated that titanium alloys such as PT-7M would be applicable to steam generator materials

Hand and nickel-titanium root canal instrumentation performed by dental students: a micro-computed tomographic study.

Science.gov (United States)

Peru, M; Peru, C; Mannocci, F; Sherriff, M; Buchanan, L S; Pitt Ford, T R

2006-02-01

The aim of this study was to evaluate root canals instrumented by dental students using the modified double-flared technique, nickel-titanium (NiTi) rotary System GT files and NiTi rotary ProTaper files by micro-computed tomography (MCT). A total of 36 root canals from 18 mesial roots of mandibular molar teeth were prepared; 12 canals were prepared with the modified double-flared technique, using K-flexofiles and Gates-Glidden burs; 12 canals were prepared using System GT and 12 using ProTaper rotary files. Each root was scanned using MCT preoperatively and postoperatively. At the coronal and mid-root sections, System GT and ProTaper files produced significantly less enlarged canal cross-sectional area, volume and perimeter than the modified double-flared technique (P ProTaper (P ProTaper and System GT were able to prepare root canals with little or no procedural error compared with the modified double-flared technique. Under the conditions of this study, inexperienced dental students were able to prepare curved root canals with rotary files with greater preservation of tooth structure, low risk of procedural errors and much quicker than with hand instruments.

Urethra sparing - potential of combined Nickel-Titanium stent and intensity modulated radiation therapy in prostate cancer.

Science.gov (United States)

Thomsen, Jakob Borup; Arp, Dennis Tideman; Carl, Jesper

2012-05-01

To investigate a novel method for sparing urethra in external beam radiotherapy of prostate cancer and to evaluate the efficacy of such a treatment in terms of tumour control using a mathematical model. This theoretical study includes 20 patients previously treated for prostate cancer using external beam radiotherapy. All patients had a Nickel-Titanium (Ni-Ti) stent inserted into the prostate part of urethra. The stent has been used during the treatment course as an internal marker for patient positioning prior to treatment. In this study the stent is used for delineating urethra while intensity modulated radiotherapy was used for lowering dose to urethra. Evaluation of the dose plans were performed using a tumour control probability model based on the concept of uniform equivalent dose. The feasibility of the urethra dose reduction method is validated and a reduction of about 17% is shown to be possible. Calculations suggest a nearly preserved tumour control probability. A new concept for urethra dose reduction is presented. The method relies on the use of a Ni-Ti stent as a fiducial marker combined with intensity modulated radiotherapy. Theoretical calculations suggest preserved tumour control. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

[Utility of nickel-titanium shape memory alloys of vertebral body reduction fixator with assisted distraction bar].

Science.gov (United States)

Man, Yi; Zheng, Yue-huan; Cao, Peng; Chen, Bo; Zheng, Tao; Sun, Chang-hui; Lu, Jiong

2011-06-07

To test the nickel-titanium (Ni-Ti) shape memory alloys of vertebral body reduction fixator with assisted distraction bar for the treatment of traumatic and osteoporotic vertebral body fracture. A Ni-Ti shape memory alloys of vertebral body reduction fixator with assisted distraction bar was implanted into the compressed fracture specimens through vertebral pedicle with the radiographic monitoring to reduce the collapsed endplate as well as distract the compressed vertebral fracture. Radiographic film and computed tomographic reconstruction technique were employed to evaluate the effects of reduction and distraction. A biomechanic test machine was used to measure the fatigue and the stability of deformation of fixation segments. Relying on the effect of temperature shape memory, such an assembly could basically reduce the collapsed endplate as well as distract the compressed vertebral fracture. And when unsatisfied results of reduction and distraction occurred, its super flexibility could provide additional distraction strength. A Ni-Ti shape memory alloys of vertebral body reduction fixator with assisted distraction bar may provide effective endplate reduction, restore the vertebral height and the immediate biomechanic spinal stability. So the above assembly is indicated for the treatment of traumatic and osteoporotic vertebral body fracture.

Experimental study of different nickel-titanium memory tracheal stents in dogs

International Nuclear Information System (INIS)

Lang Xu; He Nengshu; Fan Hailun

2009-01-01

Objective: Since membrane -covered metal tracheal stent was applied successfully to treat the airway stenosis, it has been widely used and obtained satisfactory result during the past years. The purpose of our study was provide theoretical rational for treatment with membrane-covered tracheal stent by using animal experiment. Methods: The nickel- titanium memory stents of 22 mm in diameter and 6 cm in length were deployed in 18 dogs. The dogs were grouped into full- length membrane-covered group (n=6), partial-length membrane-covered group (membrane was covered for 4 cm in the medial part of the stent, n=6), and naked stent group (n=6). After the stent placement dysphagia or dysphonia was monitored daily. Twenty-four weeks later, the dogs were executed. Speiments were taken from the cephalic, medial, and caudal trachea under the stent. HE stain and proliferating cell nuclear antigen (PCNA) were evaluated. Results: After the stent placement, no dyspnea, dysphagia or dysphonia but cough was present in each dog. There was no significant difference in symptom between the three groups. Inflammation reaction, metaplasia from low columnar epithelium to spuamous epithelium, and mild granulation tissue hyperplasia in the underlying mucosa were present in each group. However, fibrosis and tracheal straitness were present only in the non-membrane-covered area, but not in the membrane-covered area. More PCNA expression was observed in the non-membrane -covered area than in the membrane-covered area. Conclusion: Both membrane-covered and non-membrane-covered stents can cause similar symptoms. However, the membrane -covered tracheal stent has good biological compatibility and would not induce tracheal straitness. The non-membrane -covered tracheal stent could induce a severe pathologic reaction and tracheal straitness. (authors)

Fluoride influences nickel-titanium orthodontic wires′ surface texture and friction resistance

Directory of Open Access Journals (Sweden)

Mona Aly Abbassy

2016-01-01

Full Text Available Objectives: The aim of this study was to investigate the effects exerted by the acidulated fluoride gel on stainless steel and nickel-titanium (Ni-Ti orthodontic wires. Materials and Methods: Sixty stainless steel and Ni-Ti orthodontic archwires were distributed into forty archwires used for in vitro study and twenty for in situ study. Fluoride was applied for 1 h in the in vitro experiment while it was applied for 5 min in the in situ experiment. The friction resistance of all wires with ceramic brackets before/after topical fluoride application was measured using a universal testing machine at 1 min intervals of moving wire. Moreover, surface properties of the tested wires before/after fluoride application and before/after friction test were examined by a scanning electron microscope (SEM. Dunnett′s t-test was used to compare frictional resistance of as-received stainless steel wires and Ni-Ti wires to the wires treated by fluoride in vitro and in situ (P < 0.05. Two-way ANOVA was used to compare the effect of fluoride application and type of wire on friction resistance in vitro and in situ (P < 0.05. Results: Ni-Ti wires recorded significantly high friction resistance after fluoride application when compared to stainless steel wires in vitro, P < 0.05. Fluoride application did not significantly affect the friction resistance of the tested wires in situ, P < 0.05. SEM observation revealed deterioration of the surface texture of the Ni-Ti wires after fluoride application in vitro and in situ. Conclusions: The in vitro fluoride application caused an increase in friction resistance of Ni-Ti wires when compared to stainless steel wires. In vitro and in situ fluoride application caused deterioration in surface properties of Ni-Ti wires.

Comparison of the cyclic fatigue resistance of 5 different rotary pathfinding instruments made of conventional nickel-titanium wire, M-wire, and controlled memory wire.

Science.gov (United States)

Capar, Ismail Davut; Kaval, Mehmet Emin; Ertas, Hüseyin; Sen, Bilge Hakan

2015-04-01

This study compared the cyclic fatigue resistance of current nickel-titanium rotary path-finding instruments. Five types of nickel-titanium rotary pathfinding instruments were used in steel canals with a 90° curvature and a curvature radius of 3 mm (n = 10) and 5 mm (n = 10). The cyclic fatigue of the following instruments was tested at 4 mm from the tip: PathFile (#16 and a .02 taper; Dentsply Maillefer, Ballaigues, Switzerland), G-File (#12 and a .03 taper; Micro-Mega, Besançon Cedex, France), Scout Race (#15 and a .02 taper; FKG Dentaire, La Chaux-de-Fonds, Switzerland), HyFlex GPF (#15 and a .02 taper; Coltene-Whaledent, Allstetten, Switzerland), and ProGlider (#16 with a mean taper of .04125 and a .02 at the first 4 mm from the tip, Dentsply Maillefer). The length of the fractured parts was measured, and the number of cycles to fracture (NCF) was calculated. The data were statistically analyzed using Kruskal-Wallis and Mann-Whitney tests (α = .05). After Bonferroni correction, the new P value was set as .005. The difference in the cyclic fatigue of all the files at both curvatures was statistically significant (P values from .0035 to less than .0001). The ranking of the instruments from the highest to the lowest NCF was as follows: HyFlex GPF, G files, ProGlider, PathFile, and Scout Race. The length of the fractured part of the instruments was similar in all the groups (P > .05). All the tested instruments had a lower NCF at a curvature radius of 3 mm when compared with a curvature radius of 5 mm (P instrument was the highest, and the curvature radius had a significant effect on the fatigue resistance. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Relationship between surface properties (roughness, wettability) of titanium and titanium alloys and cell behaviour

International Nuclear Information System (INIS)

Ponsonnet, L.; Reybier, K.; Jaffrezic, N.; Comte, V.; Lagneau, C.; Lissac, M.; Martelet, C.

2003-01-01

Cell attachment and spreading to titanium-based alloy surfaces is a major parameter in implant technology. In this paper, substratum surface hydrophobicity, surface free energy, interfacial free energy and surface roughness were investigated to ascertain which of these parameters is predominant in human fibroblast spreading. Two methods for contact angle measurement were compared: the sessile drop method and the captive bubble two-probe method. The relationship between surface roughness and the sessile drop contact angles of various engineered titanium surfaces such as commercial pure titanium (cp-Ti), titanium-aluminium-vanadium alloy (Ti-6Al-4V), and titanium-nickel (NiTi), was shown. Surface free energy (SFE) calculations were performed from contact angles obtained on smooth samples based on the same alloys in order to eliminate the roughness effect. SFE of the surfaces have been calculated using the Owens-Wendt (OW) and Van Oss (VO) approaches with the sessile drop method. The OW calculations are used to obtain the dispersive (γ d ) and polar (γ p ) component of SFE, and the VO approach allows to reach the apolar (γ LW ) and the polar acid-base component (γ ab ) of the surface. From captive bubble contact angle experiments (air or octane bubble under water), the interfacial free energy of the different surfaces in water was obtained. A relationship between cell spreading and the polar component of SFE was found. Interfacial free energy values were low for all the investigated surfaces indicating good biocompatibility for such alloys

Laboratory comparison of the mechanical properties of TRUShape with several nickel-titanium rotary instruments.

Science.gov (United States)

Elnaghy, A M; Elsaka, S E

2017-08-01

To assess and compare the mechanical properties of TRUShape (TRS) with several nickel-titanium rotary instruments. Cyclic fatigue, torsional resistance, flexibility and surface microhardness of TRS (size 25, 0.06v taper), ProTaper Next X2 (PTN X2, size 25, 0.06 taper), ProTaper Gold (PTG F2; size 25, 0.08 taper) and ProTaper Universal (PTU F2; size 25, 0.08 taper) instruments were evaluated. The topographical structures of the fracture surfaces of instruments were assessed using a scanning electron microscope. The cyclic fatigue resistance, torsional resistance and microhardness data were analysed using one-way analysis of variance (anova) and Tukey's post hoc tests. The fragment length and bending resistance data were analysed statistically with the Kruskal-Wallis H-test and Mann-Whitney U-tests. The statistical significance level was set at P instruments revealed significantly higher resistance to cyclic fatigue than TRS and PTU instruments (P instruments revealed significantly higher torsional resistance compared with the other instruments (P instrument had significantly higher flexibility than the other tested brands (P instruments had lower resistance to cyclic fatigue and lower flexibility compared with PTG and PTN instruments. TRS, PTG and PTU instruments had lower resistance to torsional stress than PTN instruments. TRS and PTG instruments had comparable surface microhardness. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Deformation and fracture of K3 rotary nickel-titanium endodontic instruments after clinical use.

Science.gov (United States)

Shen, S M; Deng, M; Wang, P P; Chen, X M; Zheng, L W; Li, H L

2016-11-01

The aim was to evaluate the incidence and type of defects that occurred with K3 rotary nickel-titanium instruments during routine clinical use. A total of 2397 K3 (G-PACKS, SybronEndo, West Collins, Orange, CA, USA) instruments were collected from a graduate endodontic clinic over 21 months. All the instruments were limited to a maximum use of 30 canal preparations. The collected instruments were measured by a digital caliper to determine whether any fractures had occurred and then were visually inspected for deformation and fracture under a stereomicroscope. The surfaces of fractured instruments were further evaluated under a scanning electron microscope. Data were analysed using chi-square test and Kruskal-Wallis test. The incidence of instrument defect was 5.63%, consisting of 3.59% fractures and 2.05% deformations. The defect rates of 0.04 and 0.06 files were statistically higher than the other taper groups (P  0.05). For the fractured instruments, 63.95% failed from flexural fatigue, whilst 36.05% failed from torsion. Flexural fracture was the major mode of fracture for instruments with larger taper. A routine check for instrument integrity particularly for 0.04 and 0.06 files at high magnification is recommended after each clinical use. © 2015 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Cyclic fatigue resistance of XP-endo Shaper compared with different nickel-titanium alloy instruments.

Science.gov (United States)

Elnaghy, Amr; Elsaka, Shaymaa

2018-04-01

The aims of this study were to assess and compare the resistance to cyclic fatigue of XP-endo Shaper (XPS; FKG Dentaire, La Chaux-de-Fonds, Switzerland) instruments with TRUShape (TRS; Dentsply Tulsa Dental Specialties, Tulsa, OK, USA), HyFlex CM (HCM; Coltene, Cuyahoga Falls, OH, USA), Vortex Blue (VB; Dentsply Tulsa Dental Specialties), and iRace (iR; FKG Dentaire) nickel-titanium rotary instruments at body temperature. Size 30, 0.01 taper of XPS, size 30, 0.04 taper of HCM, VB, iR, and size 30, 0.06 taper of TRS instruments were immersed in saline at 37 ± 1 °C during cyclic fatigue testing. The instruments were tested with 60° angle of curvature and a 3-mm radius of curvature. The number of cycles to failure (NCF) was calculated and the length of the fractured segment was measured. Fractographic examination of the fractured surface was performed using a scanning electron microscope. The data were analyzed statistically using Kruskal-Wallis H test and Mann-Whitney U tests. Statistical significance was set at P ductile fracture of cyclic fatigue failure. XPS instruments exhibited greater cyclic fatigue resistance compared with the other tested instruments. XP-endo Shaper instruments could be used more safely in curved canals due to their higher fatigue resistance.

Tailoring the magnetic properties of new Fe-Ni-Co-Al-(Ta,Nb)-B superelastic rapidly quenched microwires

International Nuclear Information System (INIS)

Borza, F.; Lupu, N.; Dobrea, V.; Chiriac, H.

2015-01-01

Ferromagnetic Fe-Ni-Co-Al-(Ta,Nb)-B microwires with diameters from 170 μm to 50 μm, which possess both superelastic and good magnetic properties, have been prepared by rapid quenching from the melt using the in rotating water spinning technique followed by cold-drawing and ageing. The cold-drawing and annealing processes lead to the initialization of premartensitic phases as confirmed by the X-ray diffraction and scanning transmission electron microscopic investigations, more significantly in the 50 μm cold-drawn microwires. An increase in the coercive field and in the saturation magnetization has been obtained by annealing, more importantly in the case of Nb-containing alloy. Ageing by thermal or current annealing led to the initialization of the superelastic effect. High values of strain of up to 1.8%, very good repeatability under successive loading, and values of superelastic effect of up to 1.2% have been achieved. The structural analysis coupled with the stress-strain data suggests that these materials annealed at 800 °C have superelastic potential at reduced ageing times. The magnetic behavior was found to be easily tailored through both thermal and thermomagnetic treatments with changes in the magnetic parameters which can be contactless detected. The results are important for future applications where both mechanical and magnetic properties matter, i.e., sensing/actuating systems

Superelastic behavior and damping capacity of CuAlBe alloys

International Nuclear Information System (INIS)

Montecinos, Susana; Moroni, Maria Ofelia; Sepulveda, Aquiles

2006-01-01

Shape memory alloys (SMAs) showing the superelastic effect, dissipate energy through hysteretic cycles up to large strain amplitudes, without remnant strains after unloading. This effect is associated with a reversible stress-induced martensitic transformation. In this paper, the behavior of copper-based SMAs is examined, with the perspective of potential applications in seismic-energy dissipative devices. In particular, two different compositions of CuAlBe are characterized using chemical analysis, differential scanning calorimetry (DSC), light and scanning electron microscopy and X-rays diffraction. Mechanical and hysteretic damping properties are determined from cyclic tensile and tension-compression tests, for different strain amplitudes and frequencies. Both alloys show superelastic behavior, although hysteresis loops differ, due to differences in the composition and transformation phase temperatures. Equivalent damping up to 5% was obtained for the largest strain imposed. Frequency, in the range of interest for seismic applications, had a small influence on the damping values. It is concluded that alloy Cu-11.8 wt.% Al-0.5 wt.% Be best exhibited properties for the application intended

Influence of operator's experience on root canal shaping ability with a rotary nickel-titanium single-file reciprocating motion system.

Science.gov (United States)

Muñoz, Estefanía; Forner, Leopoldo; Llena, Carmen

2014-04-01

The aim of this study was to evaluate the influence of the operator's experience on the shaping of double-curvature simulated root canals with a nickel-titanium single-file reciprocating motion system. Sixty double-curvature root canals simulated in methacrylate blocks were prepared by 10 students without any experience in endodontics and by 10 professionals who had studied endodontics at the postgraduate level. The Reciproc-VDW system's R25 file was used in the root canal preparation. The blocks were photographed before and after the instrumentation, and the time of instrumentation was also evaluated. Changes in root canal dimensions were analyzed in 6 positions. Significant differences (P file reciprocating motion system Reciproc is not seen to be influenced by the operator's experience regarding the increase of the canal area. Previous training and the need to acquire experience are important in the use of this system, in spite of its apparent simplicity. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Ultralight and fire-resistant ceramic nanofibrous aerogels with temperature-invariant superelasticity.

Science.gov (United States)

Si, Yang; Wang, Xueqin; Dou, Lvye; Yu, Jianyong; Ding, Bin

2018-04-01

Ultralight aerogels that are both highly resilient and compressible have been fabricated from various materials including polymer, carbon, and metal. However, it has remained a great challenge to realize high elasticity in aerogels solely based on ceramic components. We report a scalable strategy to create superelastic lamellar-structured ceramic nanofibrous aerogels (CNFAs) by combining SiO 2 nanofibers with aluminoborosilicate matrices. This approach causes the random-deposited SiO 2 nanofibers to assemble into elastic ceramic aerogels with tunable densities and desired shapes on a large scale. The resulting CNFAs exhibit the integrated properties of flyweight densities of >0.15 mg cm -3 , rapid recovery from 80% strain, zero Poisson's ratio, and temperature-invariant superelasticity to 1100°C. The integral ceramic nature also provided the CNFAs with robust fire resistance and thermal insulation performance. The successful synthesis of these fascinating materials may provide new insights into the development of ceramics in a lightweight, resilient, and structurally adaptive form.

High maneuverability guidewire with functionally graded properties using new superelastic alloys.

Science.gov (United States)

Sutou, Y; Yamauchi, K; Suzuki, M; Furukawa, A; Omori, T; Takagi, T; Kainuma, R; Nishida, M; Ishida, K

2006-01-01

Nitinol shape memory alloys (SMAs) are attracting considerable attention as core materials for medical guidewires because of their excellent flexibility and shape retention. However, since Nitinol guidewires possess low rigidity, the pushability and torquability of the guidewires are insufficient. On the other hand, although guidewires made of stainless steel have high pushability, plastic deformation occurs easily. We have developed a new class of superelastic guidewires with functionally graded properties from the tip to the end by using new SMA core materials such as Cu-Al-Mn-based or Ni-free Ti-Mo-Sn SMAs. The tip portion of the guidewire shows excellent superelasticity (SE), while the body portion possesses high rigidity. These functionally graded characteristics can be realized by microstructural control. These guidewires with functionally graded properties show excellent pushability and torquability and are considerably easier to handle than conventional guidewires with Nitinol or stainless steel cores. Moreover, a metallic catheter using a Ni-free Ti-based SMA with high biocompatibility is introduced.

Study of alumina-trichite reinforcement of a nickel-based matric by means of powder metallurgy

Science.gov (United States)

Walder, A.; Hivert, A.

1982-01-01

Research was conducted on reinforcing nickel based matrices with alumina trichites by using powder metallurgy. Alumina trichites previously coated with nickel are magnetically aligned. The felt obtained is then sintered under a light pressure at a temperature just below the melting point of nickel. The halogenated atmosphere technique makes it possible to incorporate a large number of additive elements such as chromium, titanium, zirconium, tantalum, niobium, aluminum, etc. It does not appear that going from laboratory scale to a semi-industrial scale in production would create any major problems.

Corrosion of Nickel-Titanium Orthodontic Archwires in Saliva and Oral Probiotic Supplements

Directory of Open Access Journals (Sweden)

Gianluca Turco

2017-01-01

Full Text Available Objectives: The aim of the study was to examine how probiotic supplements affect the corrosion stability of orthodontic archwires made of nickel-titanium alloy (NiTi. Materials and Methods: Ni-Ti archwires (0.508x0.508 and having the length of 2.5 cm were tested. The archwires (composition Ni=50.4%, Ti=49.6% were uncoated, nitrified and rhodium coated. Surface microgeometry was observed by using scanning electron microscope and surface roughness was measured by profilometer through these variables: roughness average, maximum height and maximum roughness depth. Corrosion was examined by electrochemical method of cyclic polarisation. Results: Rhodium coated alloy in saliva has significantly higher general corrosion in saliva than nitrified alloy and uncoated alloy, with large effect size (p=0.027; η2=0.700. In the presence of probiotics, the result was even more pronounced (p<0.001; η2=0.936. Probiotic supplement increases general and localised corrosion of rhodium coated archwire and slightly decreases general corrosion and increases localised corrosion in uncoated archwire , while in the case of nitrified archwire the probability of corrosion is very low. The differences in surface roughness between NiTi wires before corrosion are not significant. Exposure to saliva decreases roughness average in rhodium coated wire (p=0.015; η2=0.501. Media do not significantly influence surface microgeometry in nitrified and uncoated wires. Conclusion: Probiotic supplement affects corrosion depending on the type of coating of the NiTi archwire. It increases general corrosion of rhodium coated wire and causes localised corrosion of uncoated and rhodium coated archwire. Probiotic supplement does not have greater influence on surface roughness compared to that of saliva.

Selective laser melting of Ni-rich NiTi: selection of process parameters and the superelastic response

Science.gov (United States)

Shayesteh Moghaddam, Narges; Saedi, Soheil; Amerinatanzi, Amirhesam; Saghaian, Ehsan; Jahadakbar, Ahmadreza; Karaca, Haluk; Elahinia, Mohammad

2018-03-01

Material and mechanical properties of NiTi shape memory alloys strongly depend on the fabrication process parameters and the resulting microstructure. In selective laser melting, the combination of parameters such as laser power, scanning speed, and hatch spacing determine the microstructural defects, grain size and texture. Therefore, processing parameters can be adjusted to tailor the microstructure and mechanical response of the alloy. In this work, NiTi samples were fabricated using Ni50.8Ti (at.%) powder via SLM PXM by Phenix/3D Systems and the effects of processing parameters were systematically studied. The relationship between the processing parameters and superelastic properties were investigated thoroughly. It will be shown that energy density is not the only parameter that governs the material response. It will be shown that hatch spacing is the dominant factor to tailor the superelastic response. It will be revealed that with the selection of right process parameters, perfect superelasticity with recoverable strains of up to 5.6% can be observed in the as-fabricated condition.

Computational design of precipitation-strengthened titanium-nickel-based shape memory alloys

Science.gov (United States)

Bender, Matthew D.

Motivated by performance requirements of future medical stent applications, experimental research addresses the design of novel TiNi-based, superelastic shape-memory alloys employing nanoscale precipitation strengthening to minimize accommodation slip for cyclic stability and to increase output stress capability for smaller devices. Using a thermodynamic database describing the B2 and L21 phases in the Al-Ni-Ti-Zr system, Thermo-Calc software was used to assist modeling the evolution of phase composition during 600°C isothermal evolution of coherent L21 Heusler phase precipitation from supersaturated TiNi-based B2 phase matrix in an alloy experimentally characterized by atomic-scale Local Electrode Atom Probe (LEAP) microanalysis. Based on measured evolution of the alloy hardness (under conditions stable against martensitic transformation) a model for the combined effects of solid solution strengthening and precipitation strengthening was calibrated, and the optimum particle size for efficient strengthening was identified. Thermodynamic modeling of the evolution of measured phase fractions and compositions identified the interfacial capillary energy enabling thermodynamic design of alloy microstructure with the optimal strengthening particle size. Extension of alloy designs to incorporate Pt and Pd for reducing Ni content, enhancing radiopacity, and improving manufacturability were considered using measured Pt and Pd B2/L2 1 partitioning coefficients. After determining that Pt partitioning greatly increases interphase misfit, full attention was devoted to Pd alloy designs. A quantitative approach to radiopacity was employed using mass attenuation as a metric. Radiopacity improvements were also qualitatively observed using x-ray fluoroscopy. Transformation temperatures were experimentally measured as a function of Al and Pd content. Redlich-Kister polynomial modeling was utilized for the dependence of transformation reversion Af temperature on B2 matrix phase

Effect of chemical ordering annealing on martensitic transformation and superelasticity in polycrystalline Ni–Mn–Ga microwires

Energy Technology Data Exchange (ETDEWEB)

Qian, M.F. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Advanced Composites Centre for Innovation and Science (ACCIS), University of Bristol, Queen’s Building, University Walk, Bristol BS8 1TR (United Kingdom); Zhang, X.X., E-mail: xxzhang@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wei, L.S.; Geng, L. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Peng, H.X., E-mail: hxpengwork@zju.edu.cn [Institute for Composites Science Innovation (InCSI), School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

2015-10-05

Highlights: • Chemical ordering annealing on Ni–Mn–Ga microwires was found to reduce the defect density and internal stress. • Chemical ordering annealing on Ni–Mn–Ga microwires was found to increase the MT temperatures, Curie point and saturation magnetization. • Chemical ordering annealing on Ni–Mn–Ga microwires was found to decrease the SIM stress and improve the superelastic reversibility. • Chemical ordering annealing on Ni–Mn–Ga microwires was found to weaken the temperature dependences of the superelastic stresses. - Abstract: Polycrystalline Ni–Mn–Ga microwires of diameter 30–80 μm were prepared by melt-extraction technique on a large scale. The rapidly solidified microwires exhibit a fairly high ductility and excellent shape memory property. Here, with the aim to reduce the defect density, internal stress and compositional inhomogeneity in the as-extracted microwires, a stepwise chemical ordering annealing heat treatment was carried out and the effect of annealing on martensitic transformation, magnetic properties and superelastic behavior were investigated. The results indicate that annealing increase the transformation temperature and decrease the transformation hysteresis. These are related to composition homogenization, increase of atomic ordering and decrease in internal stress and defects. During mechanical tests, the stress-induced martensite (SIM) formation took place at a much lower stress after annealing treatment. The annealed microwires also demonstrate a lower superelastic hysteresis and a higher recovery rate compared to the as-extracted microwires. The temperature dependence of SIM stress is weaker after annealing, which is related to the enthalpy change (ΔH) and phase transformation temperature change according to the Clausius–Clapeyron relation.

Microstructure and mechanical behavior of superelastic Ti-24Nb-0.5O and Ti-24Nb-0.5N biomedical alloys.

Science.gov (United States)

Ramarolahy, A; Castany, P; Prima, F; Laheurte, P; Péron, I; Gloriant, T

2012-05-01

In this study, the microstructure and the mechanical properties of two new biocompatible superelastic alloys, Ti-24Nb-0.5O and Ti-24Nb-0.5N (at.%), were investigated. Special attention was focused on the role of O and N addition on α(″) formation, supereleastic recovery and mechanical strength by comparison with the Ti-24Nb and Ti-26Nb (at.%) alloy compositions taken as references. Microstructures were characterized by optical microscopy, X-ray diffraction and transmission electron microscopy before and after deformation. The mechanical properties and the superelastic behavior were evaluated by conventional and cyclic tensile tests. High tensile strength, low Young's modulus, rather high superelastic recovery and excellent ductility were observed for both superelastic Ti-24Nb-0.5O and Ti-24Nb-0.5N alloys. Deformation twinning was shown to accommodate the plastic deformation in these alloys and only the {332} twinning system was observed to be activated by electron backscattered diffraction analyses. Copyright © 2012 Elsevier Ltd. All rights reserved.

The effect of SF6 addition in a Cl2/Ar inductively coupled plasma for deep titanium etching

Science.gov (United States)

Laudrel, E.; Tillocher, T.; Meric, Y.; Lefaucheux, P.; Boutaud, B.; Dussart, R.

2018-05-01

Titanium is a material of interest for the biomedical field and more particularly for body implantable devices. Titanium deep etching by plasma was carried out in an inductively coupled plasma with a chlorine-based chemistry for the fabrication of titanium-based microdevices. Bulk titanium etch rate was first studied in Cl2/Ar plasma mixture versus the source power and the self-bias voltage. The plasma was characterized by Langmuir probe and by optical emission spectroscopy. The addition of SF6 in the plasma mixture was investigated. Titanium etch rate was optimized and reached a value of 2.4 µm · min-1. The nickel hard mask selectivity was also enhanced. The etched titanium surface roughness was reduced significantly.

Three-dimensional quantification of pretorqued nickel-titanium wires in edgewise and prescription brackets.

Science.gov (United States)

Mittal, Nitika; Xia, Zeyang; Chen, Jie; Stewart, Kelton T; Liu, Sean Shih-Yao

2013-05-01

To quantify the three-dimensional moments and forces produced by pretorqued nickel-titanium (NiTi) rectangular archwires fully engaged in 0.018- and 0.022-inch slots of central incisor and molar edgewise and prescription brackets. Ten identical acrylic dental models with retroclined maxillary incisors were fabricated for bonding with various bracket-wire combinations. Edgewise, Roth, and MBT brackets with 0.018- and 0.022-inch slots were bonded in a simulated 2 × 4 clinical scenario. The left central incisor and molar were sectioned and attached to load cells. Correspondingly sized straight and pretorqued NiTi archwires were ligated to the brackets using 0.010-inch ligatures. Each load cell simultaneously measured three force (Fx, Fy, Fz) and three moment (Mx, My, Mz) components. The faciolingual, mesiodistal, and inciso-occluso/apical axes of the teeth corresponded to the x, y, and z axes of the load cells, respectively. Each wire was removed and retested seven times. Three-way analysis of variance (ANOVA) examined the effects of wire type, wire size, and bracket type on the measured orthodontic load systems. Interactions among the three effects were examined and pair-wise comparisons between significant combinations were performed. The force and moment components on each tooth were quantified according to their local coordinate axes. The three-way ANOVA interaction terms were significant for all force and moment measurements (P .05). The pretorqued wire generates a significantly larger incisor facial crown torquing moment in the MBT prescription compared to Roth, edgewise, and the straight NiTi wire.

Influence of cyclic torsional preloading on cyclic fatigue resistance of nickel - titanium instruments.

Science.gov (United States)

Pedullà, E; Lo Savio, F; Boninelli, S; Plotino, G; Grande, N M; Rapisarda, E; La Rosa, G

2015-11-01

To evaluate the effect of different torsional preloads on cyclic fatigue resistance of endodontic rotary instruments constructed from conventional nickel-titanium (NiTi), M-Wire or CM-Wire. Eighty new size 25, 0.06 taper Mtwo instruments (Sweden & Martina), size 25, 0.06 taper HyFlex CM (Coltene/Whaledent, Inc) and X2 ProTaper Next (Dentsply Maillefer) were used. The Torque and distortion angles at failure of new instruments (n = 10) were measured, and 0% (n = 10), 25%, 50% and 75% (n = 20) of the mean ultimate torsional strength as preloading condition were applied according to ISO 3630-1 for each brand. The twenty files tested for every extent of preload were subjected to 20 or 40 torsional cycles (n = 10). After torsional preloading, the number of cycles to failure was evaluated in a simulated canal with 60° angle of curvature and 5 mm of radius of curvature. Data were analysed using two-way analysis of variance. The fracture surface of each fragment was examined with a scanning electron microscope (SEM). Data were analysed by two-way analyses of variance. Preload repetitions did not influence the cyclic fatigue of the three brands; however, the 25%, 50% and 75% torsional preloading significantly reduced the fatigue resistance of all instruments tested (P 0.05). Torsional preloads reduced the cyclic fatigue resistance of conventional and treated (M-wire and CM-wire) NiTi rotary instruments except for size 25, 0.06 taper HyFlex CM instruments with a 25% of torsional preloading. © 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.

A comparison of nickel-titanium rotary instruments manufactured using different methods and cross-sectional areas: ability to resist cyclic fatigue.

Science.gov (United States)

Oh, So-Ram; Chang, Seok-Woo; Lee, Yoon; Gu, Yu; Son, Won-Jun; Lee, Woocheol; Baek, Seung-Ho; Bae, Kwang-Shik; Choi, Gi-Woon; Lim, Sang-Min; Kum, Kee-Yeon

2010-04-01

This study examined the effect of the manufacturing methods (ground, electropolished, and twisted) and the cross-sectional area (CSA) of nickel-titanium (NiTi) rotary instruments on their cyclic fatigue resistance. A total of 80 NiTi rotary instruments (ISO 25/.06 taper) from 4 brands (K3, ProFile, RaCe, and TF) were rotated in a simulated root canal with pecking motion until fracture. The number of cycles to failure (NCF) was calculated. The CSA at 3 mm from the tip of new instruments of each brand was calculated. The correlation between the CSA and NCF was evaluated. All fractured surfaces were analyzed using a scanning electron microscope to determine the fracture mode. The TF instruments were the most resistant to fatigue failure. The resistance to cyclic failure increased with decreasing CSA. All fractured surfaces showed the coexistence of ductile and brittle properties. The CSA had a significant effect on the fatigue resistance of NiTi rotary instruments. Copyright 2010 Mosby, Inc. All rights reserved.

Influence of rotational speed on the cyclic fatigue of rotary nickel-titanium endodontic instruments.

Science.gov (United States)

Lopes, Hélio P; Ferreira, Alessandra A P; Elias, Carlos N; Moreira, Edson J L; de Oliveira, Júlio C Machado; Siqueira, José F

2009-07-01

During the preparation of curved canals, rotary nickel-titanium (NiTi) instruments are subjected to cyclic fatigue, which can lead to instrument fracture. Although several factors may influence the cyclic fatigue resistance of instruments, the role of the rotational speed remains uncertain. This study was intended to evaluate the effects of rotational speed on the number of cycles to fracture of rotary NiTi instruments. ProTaper Universal instruments F3 and F4 (Maillefer SA, Ballaigues, Switzerland) were used in an artificial curved canal under rotational speeds of 300 rpm or 600 rpm. The artificial canal was made of stainless steel, with an inner diameter of 1.5 mm, total length of 20 mm, and arc at the end with a curvature radius of 6 mm. The arc length was 9.4 mm and 10.6 mm on the straight part. The number of cycles required to fracture was recorded. Fractured surfaces and the helical shafts of the fractured instruments were analyzed by scanning electron microscopy. The results showed approximately a 30% reduction in the observed number of cycles to fracture as rotational speed was increased from 300 to 600 RPM (p ductile type, and no plastic deformation was observed on the helical shaft of fractured instruments. The present findings for both F3 and F4 ProTaper instruments revealed that the increase in rotational speed significantly reduced the number of cycles to fracture.

The impact of a continuing education programme on the adoption of nickel-titanium rotary instrumentation and root-filling quality amongst a group of Swedish general dental practitioners.

Science.gov (United States)

Dahlström, L; Molander, A; Reit, C

2015-02-01

The aim of the study was to test the hypothesis that a further education programme relating to nickel-titanium rotary instrumentation (NTRI), with the concurrent activation of social/professional networks amongst all general dental practitioners (GDPs) in a public dental service in Sweden, would increase the adoption rate and improve root-filling quality. To activate the networks, the GDPs at the 25 clinics elected training coaches from amongst themselves. The coaches were educated by a specialist and were then free to organise and conduct the training of the local GDPs. However, collective hands-on training and discussions were mandatory. Lectures were held by an endodontist. The rate of adoption and root-filling quality was evaluated just before and 6 months after the education. Statistical tests were performed with chi-square using a 95% confidence interval. Nickel-titanium rotary instrumentation was adopted by 88%. Excellent root fillings (score 1) increased from 45% to 59% (P = 0.003). The rate of poor-quality root fillings (score 4 and score 5) was not affected. The quality ratio (score 1/score 5) increased from 5.36 (118/22) to 9.5 (133/14). Eleven dentists (17%) at nine different clinics produced 49% of the poor-quality root fillings (score 4 and score 5). Seventy-three per cent of these dentists stated that they had adopted NTRI. The introduction of NTRI will increase the adoption rate and the frequency of good-quality root fillings. However, it will not overcome the problems associated with dentists producing a low-quality level, even if a local professional network is activated. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Force systems in the initial phase of orthodontic treatment -- a comparison of different leveling arch wires.

Science.gov (United States)

Fuck, Lars-Michael; Drescher, Dieter

2006-01-01

The determination of orthodontically-effective forces and moments places great demands on the technical equipment. Many patients report severe pain after fixed appliance insertion. Since it is assumed that pain from orthodontic appliances is associated with the force and moment levels applied to the teeth and since the occurrence of root resorption is a common therapeutic side effect, it would seem important to know the actual magnitudes of the components of the active orthodontic force systems. The aim of the present study was therefore to measure initial force systems produced by different leveling arch-wires in a complete multi-bracket appliance and to assess whether force and moment levels can be regarded as biologically acceptable or not. The actual bracket position in 42 patients was transferred onto a measurement model. Forces and moments produced by a super-elastic nickel-titanium (NiTi) archwire, a 6-strand stainless steel archwire, and a 7-strand super-elastic NiTi archwire were determined experimentally on different teeth. Average forces and moments produced by the super-elastic NiTi arch wires were found to be the highest. In spite if their larger diameter, the stranded arch wires' average force and moment levels were lower, especially that of the stranded super-elastic archwire. Nevertheless, maximum force levels sometimes exceeded recommended values in the literature and must be considered as too high. The measured arch wires' initial force systems differed significantly depending on the type of archwire and its material structure. Stranded arch wires produced lower force and moment levels, and we recommend their use in the initial phase of orthodontic treatment.

Influence of Thin-Film Adhesives in Pullout Tests Between Nickel-Titanium Shape Memory Alloy and Carbon Fiber-Reinforced Polymer Matrix Composites

Science.gov (United States)

Quade, Derek J.; Jana, Sadhan; McCorkle, Linda S.

2018-01-01

Strips of nickel-titanium (NiTi) shape memory alloy (SMA) and carbon fiber-reinforced polymer matrix composite (PMC) were bonded together using multiple thin film adhesives and their mechanical strengths were evaluated under pullout test configuration. Tensile and lap shear tests were conducted to confirm the deformation of SMAs at room temperature and to evaluate the adhesive strength between the NiTi strips and the PMC. Optical and scanning electron microscopy techniques were used to examine the interfacial bonding after failure. Simple equations on composite tensile elongation were used to fit the experimental data on tensile properties. ABAQUS models were generated to show the effects of enhanced bond strength and the distribution of stress in SMA and PMC. The results revealed that the addition of thin film adhesives increased the average adhesive strength between SMA and PMC while halting the room temperature shape memory effect within the pullout specimen.

Finite-element analysis of NiTi wire deflection during orthodontic levelling treatment

International Nuclear Information System (INIS)

Razali, M F; Mahmud, A S; Abdullah, J; Mokhtar, N

2016-01-01

Finite-element analysis is an important product development tool in medical devices industry for design and failure analysis of devices. This tool helps device designers to quickly explore various design options, optimizing specific designs and providing a deeper insight how a device is actually performing. In this study, three-dimensional finite-element models of superelastic nickel-titanium arch wire engaged in a three brackets system were developed. The aim was to measure the effect of binding friction developed on wire-bracket interaction towards the remaining recovery force available for tooth movement. Uniaxial and three brackets bending test were modelled and validated against experimental works. The prediction made by the three brackets bending models shows good agreement with the experimental results. (paper)

Finite-element analysis of NiTi wire deflection during orthodontic levelling treatment

Science.gov (United States)

Razali, M. F.; Mahmud, A. S.; Mokhtar, N.; Abdullah, J.

2016-02-01

Finite-element analysis is an important product development tool in medical devices industry for design and failure analysis of devices. This tool helps device designers to quickly explore various design options, optimizing specific designs and providing a deeper insight how a device is actually performing. In this study, three-dimensional finite-element models of superelastic nickel-titanium arch wire engaged in a three brackets system were developed. The aim was to measure the effect of binding friction developed on wire-bracket interaction towards the remaining recovery force available for tooth movement. Uniaxial and three brackets bending test were modelled and validated against experimental works. The prediction made by the three brackets bending models shows good agreement with the experimental results.

Effect of Variable Amplitude Blocks' Ordering on the Functional Fatigue of Superelastic NiTi Wires

Science.gov (United States)

Soul, Hugo; Yawny, Alejandro

2017-12-01

Accumulation of superelastic cycles in NiTi uniaxial element generates changes on the stress-strain response. Basically, there is an uneven drop of martensitic transformation stress plateaus and an increase of residual strain. This evolution associated with deterioration of superelastic characteristics is referred to as "functional fatigue" and occurs due to irreversible microstructural changes taking place each time a material domain transforms. Unlike complete cycles, for which straining is continued up to elastic loading of martensite, partial cycles result in a differentiated evolution of those material portions affected by the transformation. It is then expected that the global stress-strain response would reflect the previous cycling history of the specimen. In the present work, the consequences of cycling of NiTi wires using blocks of different strain amplitudes interspersed in different sequences are analyzed. The effect of successive increasing, successive decreasing, and interleaved strain amplitudes on the evolution of the superelastic response is characterized. The feasibility of postulating a functional fatigue criterion similar to the Miner's cumulative damage law used in structural fatigue analysis is discussed. The relation of the observed stress-strain response with the transformational history of the specimen can be rationalized by considering that the stress-induced transformation proceeds via localized propagating fronts.

Development of medical guide wire of Cu-Al-Mn-base superelastic alloy with functionally graded characteristics.

Science.gov (United States)

Sutou, Yuji; Omori, Toshihiro; Furukawa, Akihisa; Takahashi, Yukinori; Kainuma, Ryosuke; Yamauchi, Kiyoshi; Yamashita, Shuzo; Ishida, Kiyohito

2004-04-15

A new type of medical guide wire with functionally graded hardness from the tip to the end was developed with the use of Cu-Al-Mn-based alloys. The superelasticity (SE) of the Cu-Al-Mn-based alloys in the tip is drastically improved by controlling the grain size, whereas the end of the wire is hardened using bainitic transformation by aging at around 200-400 degrees C. Therefore, the tip of the guide wire shows a superelasticity and its end has high stiffness. This guide wire with functionally graded characteristics shows excellent pushability and torquability, superior to that of the Ni-Ti guide wire. Copyright 2004 Wiley Periodicals, Inc.

Preparation of nickel-coated titanium carbide particulates and their use in the production of reinforced iron matrix composites

International Nuclear Information System (INIS)

Yi, Danqing; Yu, Pengchao; Hu, Bin; Liu, Huiqun; Wang, Bin; Jiang, Yong

2013-01-01

Highlights: • Ni-coated TiC composite powders were prepared by electroless plating. • Iron-based composites reinforced by TiC particles was prepared by HIP. • Mechanical and wear properties were improved with the addition of Ni-coated TiC. • The nickel coating promotes the formation and growth of sintering neck. - Abstract: Ni-coated titanium carbide (TiC) composite powders were prepared by electroless plating (EP). Further, using hot isostatic pressing (HIP), iron matrix composites reinforced with 4 wt% Ni-coated TiC particulates with relative density close to 100% were prepared. The microstructure and phase composition of the Ni-coated powders and the composites were analyzed using X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The results showed that the TiC particles were distributed uniformly in the matrix and were free of segregation or coarsening. Compared to the TiC particles without Ni coating, the reinforced iron-based composites containing the Ni-coated particles showed higher relative densities and better mechanical properties. The density, hardness, tensile strength, and elongation were enhanced to 99.98%, 243 HV, 565 MPa, and 11.7%, respectively in composites containing Ni-coated TiC particles from 99.70%, 210 HV, 514 MPa, and 10.3%, respectively in composites that were prepared using particles without Ni coating. In addition, the mass losses in the composites containing the Ni-coated particles were reduced by 32–75% in the abrasive wear test with various vertical loads. We propose that the nickel coatings on the particulates had a beneficial effect on the microstructure and properties of the reinforced iron-based composites is due to promotion of neck formation and growth between TiC and iron powders during sintering, which enhanced the density of the sintered compact and the bonding strength between the TiC particles and the iron matrix

Biocompatibility and Inflammatory Potential of Titanium Alloys Cultivated with Human Osteoblasts, Fibroblasts and Macrophages

Science.gov (United States)

Markhoff, Jana; Krogull, Martin; Schulze, Christian; Rotsch, Christian; Hunger, Sandra; Bader, Rainer

2017-01-01

The biomaterials used to maintain or replace functions in the human body consist mainly of metals, ceramics or polymers. In orthopedic surgery, metallic materials, especially titanium and its alloys, are the most common, due to their excellent mechanical properties, corrosion resistance, and biocompatibility. Aside from the established Ti6Al4V alloy, shape memory materials such as nickel-titanium (NiTi) have risen in importance, but are also discussed because of the adverse effects of nickel ions. These might be reduced by specific surface modifications. In the present in vitro study, the osteoblastic cell line MG-63 as well as primary human osteoblasts, fibroblasts, and macrophages were cultured on titanium alloys (forged Ti6Al4V, additive manufactured Ti6Al4V, NiTi, and Diamond-Like-Carbon (DLC)-coated NiTi) to verify their specific biocompatibility and inflammatory potential. Additive manufactured Ti6Al4V and NiTi revealed the highest levels of metabolic cell activity. DLC-coated NiTi appeared as a suitable surface for cell growth, showing the highest collagen production. None of the implant materials caused a strong inflammatory response. In general, no distinct cell-specific response could be observed for the materials and surface coating used. In summary, all tested titanium alloys seem to be biologically appropriate for application in orthopedic surgery. PMID:28772412

Biocompatibility and Inflammatory Potential of Titanium Alloys Cultivated with Human Osteoblasts, Fibroblasts and Macrophages

Directory of Open Access Journals (Sweden)

Jana Markhoff

2017-01-01

Full Text Available The biomaterials used to maintain or replace functions in the human body consist mainly of metals, ceramics or polymers. In orthopedic surgery, metallic materials, especially titanium and its alloys, are the most common, due to their excellent mechanical properties, corrosion resistance, and biocompatibility. Aside from the established Ti6Al4V alloy, shape memory materials such as nickel-titanium (NiTi have risen in importance, but are also discussed because of the adverse effects of nickel ions. These might be reduced by specific surface modifications. In the present in vitro study, the osteoblastic cell line MG-63 as well as primary human osteoblasts, fibroblasts, and macrophages were cultured on titanium alloys (forged Ti6Al4V, additive manufactured Ti6Al4V, NiTi, and Diamond-Like-Carbon (DLC-coated NiTi to verify their specific biocompatibility and inflammatory potential. Additive manufactured Ti6Al4V and NiTi revealed the highest levels of metabolic cell activity. DLC-coated NiTi appeared as a suitable surface for cell growth, showing the highest collagen production. None of the implant materials caused a strong inflammatory response. In general, no distinct cell-specific response could be observed for the materials and surface coating used. In summary, all tested titanium alloys seem to be biologically appropriate for application in orthopedic surgery.

Optically probing torsional superelasticity in spider silks

Energy Technology Data Exchange (ETDEWEB)

Kumar, Bhupesh; Thakur, Ashish; Panda, Biswajit; Singh, Kamal P. [Department of Physical Sciences, IISER Mohali, Sector 81, Manauli, Mohali 140306 (India)

2013-11-11

We investigate torsion mechanics of various spider silks using a sensitive optical technique. We find that spider silks are torsionally superelastic in that they can reversibly withstand great torsion strains of over 10{sup 2−3} rotations per cm before failure. Among various silks from a spider, we find the failure twist-strain is greatest in the sticky capture silk followed by dragline and egg-case silk. Our in situ laser-diffraction measurements reveal that torsional strains on the silks induce a nano-scale transverse compression in its diameter that is linear and reversible. These unique torsional properties of the silks could find applications in silk-based materials and devices.

Optically probing torsional superelasticity in spider silks

International Nuclear Information System (INIS)

Kumar, Bhupesh; Thakur, Ashish; Panda, Biswajit; Singh, Kamal P.

2013-01-01

We investigate torsion mechanics of various spider silks using a sensitive optical technique. We find that spider silks are torsionally superelastic in that they can reversibly withstand great torsion strains of over 10 2−3 rotations per cm before failure. Among various silks from a spider, we find the failure twist-strain is greatest in the sticky capture silk followed by dragline and egg-case silk. Our in situ laser-diffraction measurements reveal that torsional strains on the silks induce a nano-scale transverse compression in its diameter that is linear and reversible. These unique torsional properties of the silks could find applications in silk-based materials and devices

Orthodontic applications of a superelastic shape-memory alloy model

International Nuclear Information System (INIS)

Glendenning, R.W.; Enlow, R.L.

2000-01-01

During orthodontic treatment, dental appliances (braces) made of shape memory alloys have the potential to provide nearly uniform low level stresses to dentitions during tooth movement over a large range of tooth displacement. In this paper we model superelastic behaviour of dental appliances using the finite element method and constitutive equations developed by F. Auricchio et al. Results of the mathematical model for 3-point bending and several promising 'closing loop' designs are compared with laboratory results for the same configurations. (orig.)

Shaping ability of two M-wire and two traditional nickel-titanium instrumentation systems in S-shaped resin canals.

Science.gov (United States)

Ceyhanli, K T; Kamaci, A; Taner, M; Erdilek, N; Celik, D

2015-01-01

The aim of this study was to evaluate the shaping effects of two M-wire and two traditional nickel-titanium (NiTi) rotary systems in simulated S-shaped resin canals. Forty simulated S-shaped canals in resin blocks were instrumented with two traditional (ProTaper, Sendoline S5) and two M-wire (WaveOne, GT series X) NiTi systems according to the manufacturers' instructions. Ten resin blocks were used for each system. Pre- and post-instrumentation images were captured using a stereomicroscope and superimposed with an image program. Canal transportation, material removal, and aberrations were evaluated and recorded as numeric parameters. Data were analyzed using one-way ANOVA and post-hoc Tukey tests with a 95% confidence interval. There were significant differences between systems in terms of transportation and material removal (Pwire or traditional NiTi) and kinematics (rotary or reciprocating motion) did not affect the shaping abilities of the systems. The extended file designs of highly tapered NiTi systems (ProTaper, WaveOne) resulted in greater deviations from the original root canal trace and more material removal when compared to less tapered systems (Sendoline S5, GT series X).

Effects of heat treatment and welding process on superelastic behaviour and microstructure of micro electron beam welded NiTi

Directory of Open Access Journals (Sweden)

Balz Isabel

2016-09-01

Full Text Available Medical devices with small dimensions made of superelastic NiTi become more popular, but joining these parts remains challenging. Since laser welding was found to be an option, electron beam welding seems to be an interesting alternative as it provides additional advantages due to the precise beam positioning and the high vacuum. Superelasticity is influenced by microstructure and surface layer composition that are mainly affected by welding process and by heat treatment and therefore will be investigated in the present paper.

Corrosion Characterization in Nickel Plated 110 ksi Low Alloy Steel and Incoloy 925: An Experimental Case Study

Science.gov (United States)

Thomas, Kiran; Vincent, S.; Barbadikar, Dipika; Kumar, Shresh; Anwar, Rebin; Fernandes, Nevil

2018-04-01

Incoloy 925 is an age hardenable Nickel-Iron-Chromium alloy with the addition of Molybdenum, Copper, Titanium and Aluminium used in many applications in oil and gas industry. Nickel alloys are preferred mostly in corrosive environments where there is high concentration of H2S, CO2, chlorides and free Sulphur as sufficient nickel content provides protection against chloride-ion stress-corrosion cracking. But unfortunately, Nickel alloys are very expensive. Plating an alloy steel part with nickel would cost much lesser than a part make of nickel alloy for large quantities. A brief study will be carried out to compare the performance of nickel plated alloy steel with that of an Incoloy 925 part by conducting corrosion tests. Tests will be carried out using different coating thicknesses of Nickel on low alloy steel in 0.1 M NaCl solution and results will be verified. From the test results we can confirm that Nickel plated low alloy steel is found to exhibit fairly good corrosion in comparison with Incoloy 925 and thus can be an excellent candidate to replace Incoloy materials.

The effect of titanium nickel nitride decorated carbon nanotubes-reduced graphene oxide hybrid support for methanol oxidation

Science.gov (United States)

Liu, Gen; Pan, Zhanchang; Li, Wuyi; Yu, Ke; Xia, Guowei; Zhao, Qixiang; Shi, Shikun; Hu, Guanghui; Xiao, Chumin; Wei, Zhigang

2017-07-01

Titanium nickel nitride (TiNiN) decorated three-dimensional (3D) carbon nanotubes-reduced graphene oxide (CNT-rGO), a fancy 3D platinum (Pt)-based catalyst hybrid support, is prepared by a solvothermal process followed by a nitriding process, which is tested as anodic catalyst support for the methanol oxidation reaction (MOR). The structure, morphology and composition of the synthesized TiNiN/CNT-rGO exhibits a uniform particle dispersion with high purity and interpenetrating 3D network structure. Notably, Pt/TiNiN/CNT-rGO catalyst exhibits significantly improved catalytic activity and durability for methanol oxidation in comparison with Pt/CNT-rGO and conventional Pt/C (JM). The outstanding electrochemical performance was attributed to structure and properties. That is, the 3D CNT-rGO provided a fast transport network for charge-transfer and mass-transfer as well as TiNiN NPs with good synergistic effect and the strong electronic coupling between different domains in TiNiN/CNT-rGO, thus the catalytic activity of the novel catalyst is greatly improved. These results evidences 3D TiNiN/CNT-rGO as a promising catalyst support for a wide range of applications in fuel cells.

Advances in titanium alloys

International Nuclear Information System (INIS)

Seagle, S.R.; Wood, J.R.

1993-01-01

As described above, new developments in the aerospace market are focusing on higher temperature alloys for jet engine components and higher strength/toughness alloys for airframe applications. Conventional alloys for engines have reached their maximum useful temperature of about 1000 F (540 C) because of oxidation resistance requirements. IMI 834 and Ti-1100 advanced alloys show some improvement, however, the major improvement appears to be in gamma titanium aluminides which could extend the maximum usage temperature to about 1500 F (815 C). This puts titanium alloys in a competitive position to replace nickel-base superalloys. Advanced airframe alloys such as Ti-6-22-22S, Beta C TM , Ti-15-333 and Ti-10-2-3 with higher strength than conventional Ti-6-4 are being utilized in significantly greater quantities, both in military and commercial applications. These alloys offer improved strength with little or no sacrifice in toughness and improved formability, in some cases. Advanced industrial alloys are being developed for improved corrosion resistance in more reducing and higher temperature environments such as those encountered in sour gas wells. Efforts are focused on small precious metal additions to optimize corrosion performance for specific applications at a modest increase in cost. As these applications develop, the usage of titanium alloys for industrial markets should steadily increase to approach that for aerospace applications. (orig.)

Mechanical splicing of superelastic Cu–Al–Mn alloy bars with headed ends

Science.gov (United States)

Kise, S.; Mohebbi, A.; Saiidi, M. S.; Omori, T.; Kainuma, R.; Shrestha, K. C.; Araki, Y.

2018-06-01

This paper examines the feasibility of mechanical splicing using a steel coupler to connect headed ends of superelastic Cu–Al–Mn alloy (Camalloy) bars and steel reinforcing bars to be used in concrete structures. Although threading of Camalloy is as easy as that of steel, mechanical splicing using threaded ends requires machining of Camalloy bars into dog-bone shape to avoid brittle fracture at the threaded ends. The machining process requires significant time and cost and wastes substantial amount of the material. This paper attempts to resolve this issue by applying mechanical splicing using steel couplers to connect headed ends of Camalloy and steel reinforcing bars. To study its feasibility, we prepare 3 specimens wherein both ends of each Camalloy bar (13 mm diameter and 300 mm length) are connected to steel reinforcing bars. The specimens are tested under monotonic, single-cycle, and full-cycle tension loading conditions. From these tests, we observed (1) excellent superelasticity with recoverable strain of around 6% and (2) large ductility with fracture strain of over 19%. It should be emphasized here that, in all the specimens, ductile fracture occurred at the locations apart from the headed ends. This is in sharp contrast with brittle fracture of headed superelastic Ni–Ti SMA bars, most of which took place around the headed ends. From the results of the microstructural analysis, we identified the following reasons for avoiding brittle fracture at the headed ends: (1) Precipitation hardening increases the strength around the boundary between the straight and headed (tapered) portions, where stress concentration takes place. (2) The strength of the straight portion does not increase significantly up to the ductile fracture if its grain orientation is close to 〈0 0 1〉.

Nickel silicide thin films as masking and structural layers for silicon bulk micro-machining by potassium hydroxide wet etching

International Nuclear Information System (INIS)

Bhaskaran, M; Sriram, S; Sim, L W

2008-01-01

This paper studies the feasibility of using titanium and nickel silicide thin films as mask materials for silicon bulk micro-machining. Thin films of nickel silicide were found to be more resistant to wet etching in potassium hydroxide. The use of nickel silicide as a structural material, by fabricating micro-beams of varying dimensions, is demonstrated. The micro-structures were realized using these thin films with wet etching using potassium hydroxide solution on (1 0 0) and (1 1 0) silicon substrates. These results show that nickel silicide is a suitable alternative to silicon nitride for silicon bulk micro-machining

Comparison of cyclic fatigue resistance of three different rotary nickel-titanium instruments designed for retreatment.

Science.gov (United States)

Inan, Ugur; Aydin, Cumhur

2012-01-01

A number of rotary nickel-titanium (NiTi) systems have been developed to provide better, faster, and easier cleaning and shaping of the root canal system, and recently, rotary NiTi systems designed for root canal retreatment have been introduced. Because the main problem with the rotary NiTi files is fracture, the aim of this study was to compare the cyclic fatigue resistance of 3 different rotary NiTi systems designed for root canal retreatment. Total of 60 instruments of 3 different rotary NiTi systems designed for root canal retreatment were used in this study. Twenty R-Endo R3, 20 ProTaper D3, and 20 Mtwo R (Retreatment) 25.05 instruments were tested. Cyclic fatigue testing of instruments was performed by using a device that allowed the instruments to rotate freely inside an artificial canal. Each instrument was rotated until fracture occurred, and the number of cycles to fracture for each instrument was calculated. Representative samples were also evaluated under a scanning electron microscope to confirm the fracture was flexural. Data were analyzed by using 1-way analysis of variance test. R-Endo R3 instruments showed better cyclic fatigue resistance than ProTaper D3 and Mtwo R 25.05 instruments, and the difference was statistically significant (P instruments were more resistant to fatigue failure than ProTaper D3 and Mtwo R 25.05. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Stereomicroscopic evaluation of defects caused by torsional fatigue in used hand and rotary nickel-titanium instruments.

Science.gov (United States)

Asthana, Geeta; Kapadwala, Marsrat I; Parmar, Girish J

2016-01-01

The aim of this study was to evaluate defects caused by torsional fatigue in used hand and rotary nickel-titanium (Ni-Ti) instruments by stereomicroscopic examination. One hundred five greater taper Ni-Ti instruments were used including Protaper universal hand (Dentsply Maillefer, Ballaigues, Switzerland), Protaper universal rotary (Dentsply Maillefer, Ballaigues, Switzerland), and Revo-S rotary (MicroMega, Besançon, France) files. Files were used on lower anterior teeth. After every use, the files were observed with both naked eyes and stereomicroscope at 20× magnification (Olympus, Shinjuku, Tokyo, Japan) to evaluate defects caused by torsional fatigue. Scoring was assigned to each file according to the degree of damage. The results were statistically analyzed using the Mann-Whitney U test and the Kruskal-Wallis test. A greater number of defects were seen under the stereomicroscope than on examining with naked eyes. However, the difference in methods of evaluation was not statistically significant. Revo-S files showed minimum defects, while Protaper universal hand showed maximum defects. The intergroup comparison of defects showed that the bend in Protaper universal hand instruments was statistically significant. Visible defects in Ni-Ti files due to torsional fatigue were seen by naked eyes as well as by stereomicroscope. This study emphasizes that all the files should be observed before and after every instrument cycle to minimize the risk of separation.

Orthodontic applications of a superelastic shape-memory alloy model

Energy Technology Data Exchange (ETDEWEB)

Glendenning, R.W.; Enlow, R.L. [Otago Univ., Dunedin (New Zealand). Dept. of Math. and Stat.; Hood, J.A.A. [Dept. of Oral Sciences and Orthodontics, Univ. of Otago, Dunedin (New Zealand)

2000-07-01

During orthodontic treatment, dental appliances (braces) made of shape memory alloys have the potential to provide nearly uniform low level stresses to dentitions during tooth movement over a large range of tooth displacement. In this paper we model superelastic behaviour of dental appliances using the finite element method and constitutive equations developed by F. Auricchio et al. Results of the mathematical model for 3-point bending and several promising 'closing loop' designs are compared with laboratory results for the same configurations. (orig.)

Applications and development of shape-memory and superelastic alloys in Japan

Energy Technology Data Exchange (ETDEWEB)

Takaoka, S.; Horikawa, H. [Furukawa Electric Co., Ltd., Hiratsuka (Japan); Kobayashi, J. [Japan Association of Shape Memory Alloys, Yokohama (Japan); Shimizu, K. [Kanazawa Inst. of Tech., Matsutou (Japan)

2002-07-01

The present situation of the applications and development of shape memory and superelastic alloys in Japan will collectively be introduced. Of many shape memory alloys, TiNi alloy systems have mostly been used for the applications from the point of view of fatigue and corrosion characteristics. Shape memory effect has been utilized for mainly thermal actuators with the form of coil springs. The effect associated with the B2 to R-phase transformation and its reversion exhibits recoverable strain of approximately 1%, and after a million thermal cycles the recovery characteristics are not affected. Thus, the effect is widely utilized as sensor flap of the air conditioner, water flow control valve, underfloor vent, automatic oil volume adjusting equipment for Shinkansen and water mixing valve. Another effect associated with the B2 to orthorhombic transformation and its reversion, as in TiNiCu alloys containing Cu more than 8%, can be applied to actuators required for 10,000 to 50,000 times life, and thus it is utilized as rice cooker, coffee maker and anti-scald valve. In Japan, however, the TiNi shape memory alloy systems are mainly used for applications using the superelasticity, like a rubber material. The superelasticity associated with the B2 to monoclinic stress-induced transformation and its reversion upon un-loading has been utilized as brassiere wire, eye glasses flame, antenna core wire for cellular phone and fishing wire, and that associated with the B2 to orthorhombic stress-induced transformation and its reversion upon un-loading has been as orthodontic wire, because the TiNiCu alloy wire exhibits smaller stress hysteresis than that of usual TiNi alloy wire. The TiNi shape memory alloy systems are now developed to make various shapes, such as tapes, foils and tubes, and the alloys with those shapes are examined to apply to medical uses, such as guide wire for catheter and catheter tube itself, and to any other uses. The development in Japan is rapidly

Shaping abilities of two different engine-driven rotary nickel titanium systems or stainless steel balanced-force technique in mandibular molars.

Science.gov (United States)

Matwychuk, Michael J; Bowles, Walter R; McClanahan, Scott B; Hodges, Jim S; Pesun, Igor J

2007-07-01

The purpose of this study was to compare apical transportation, working-length changes, and instrumentation time by using nickel-titanium (Ni-Ti) rotary file systems (crown-down method) or stainless steel hand files (balanced-force technique) in mesiobuccal canals of extracted mandibular molars. The curvature of each canal was determined and teeth placed into three equivalent groups. Group 1 was instrumented with Sequence (Brasseler USA, Savannah, GA) rotary files, group 2 with Liberator (Miltex Inc, York, PA) rotary files, and group 3 with Flex-R (Union Broach, New York, NY) files. Pre- and postoperative radiographs were superimposed to measure loss of working length and apical transportation as shown by changes in radius of curvature and the long-axis canal angle. Sequence rotary files, Liberator rotary files, and Flex-R hand files had similar effects on apical canal transportation and changes in working length, with no significant differences detected among the 3 groups. Hand instrumentation times were longer than with either Ni-Ti rotary group, whereas the rotary NiTi groups had a higher incidence of fracture.

The Effect of Autoclaving on Torsional Moment of Two Nickel-Titanium Endodontic Files

Science.gov (United States)

2012-01-01

titanium endodontic files 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) J. B. King, H. W. Roberts, B. E... Endodontic Journal, doi:10.1111/j.1365- 2591.2011.01958.x 45, 156–161, 2012 doi:10.1111/j.1365-2591.2011.01958.x Wiley Blackwell Publishing, 111 River...autoclaving on torsional strength of two nickel–titanium (NiTi) rotary endodontic files: Twisted Files (SybronEndo, Orange, CA, USA) and GT Series X

Titanium tungsten coatings for bioelectrochemical applications

DEFF Research Database (Denmark)

Wierzbicki, Rafal; Amato, Letizia; Łopacińska, J.

2011-01-01

This paper presents an assessment of titanium tungsten (TiW) coatings and their applicability as components of biosensing systems. The focus is put on using TiW as an electromechanical interface layer between carbon nanotube (CNT) forests and silicon nanograss (SiNG) cell scaffolds. Cytotoxicity......, applicability to plasma-enhanced chemical vapor deposition (PECVD) of aligned CNT forests, and electrochemical performance are investigated. Experiments include culturing of NIH3T3 mouse embryonic fibroblast cells on TiW coated silicon scaffolds, CNT growth on TiW substrates with nickel catalyst, and cyclic...

Adverse reactions to orthodontic appliances in nickel-allergic patients.

Science.gov (United States)

Volkman, Kristen K; Inda, Michael J; Reichl, Peter G; Zacharisen, Michael C

2007-01-01

Nickel allergy (NA) is common and causes more cases of allergic contact dermatitis (ACD) than all other metals combined. Many orthodontic appliances (ODAs) contain nickel but their clinical relevance in nickel-allergic patients is unclear. We aimed to characterize the relationship between NA and ODAs because the medical literature investigating this is controversial. A survey concerning adverse reactions to ODAs in patients with NA was distributed to members of the Wisconsin Society of Orthodontics. Forty-three surveys were analyzed. The surveyed group was experienced, representing a mean of 21.2 years in practice and averaging 242 appliances placed per year per orthodontist. Most new patients with orthodontia were 10-18 years old. Most wires used were nickel-titanium alloy. Although 76% of orthodontists inquired about NA at initial evaluation, 37% still placed nickel-containing ODAs in known nickel-allergic patients. Fifty percent placed a single intraoral appliance, observing for reactions. Three orthodontists applied ODAs to the skin similar to patch testing. Only 8 patients with reactions to ODAs were described in detail, 6 were female patients and 6 were aged 13-14 years. Intraoral and extraoral reactions were mild; diffuse urticaria was reported in one patient. Treatment included removing the appliances or changing to nonnickel alternatives with favorable outcomes. These cases, which included >33,000 patients, suggest a prevalence of 0.03%. Adverse reactions to ODAs in patients with NA have been observed but are uncommon. Using suitable alternatives, patients usually can be accommodated.

Influence of sliding friction on leveling force of superelastic NiTi arch wire: A computational analysis

Science.gov (United States)

Razali, M. F.; Mahmud, A. S.; Mokhtar, N.; Abdullah, J.

2017-10-01

This study investigated the influence of sliding friction toward the effective force of superelastic NiTi arch wire applied in orthodontic bracing for tooth leveling. A three-dimensional finite-element model integrated with superelastic subroutine and contact interaction was used to predict the contribution of friction on force-deflection curve of NiTi wire in three brackets bending configuration. It was found that the friction between the wire and the bracket increased proportionally as a function of wire deflection, thus transforming the constant force characteristic of NiTi material into a slope. The highest magnitude of sliding friction was measured to be 3.1 N and 2.2 N with respect to the activation and deactivation of the arch wire.

Spin dependence in superelastic electron scattering from Na(3P)

International Nuclear Information System (INIS)

McClelland, J.J.; Kelley, M.H.; Celotta, R.J.

1985-01-01

Measurements are presented of spin asymmetries for superelastic scattering of 10-eV spin polarized electrons from the excited Na(3P/sub 3/2/) state created by linearly polarized laser optical pumping. Asymmetries as large as 16% are observed in scattering from a state which is not spin-polarized. Results are shown both as a function of scattering angle with fixed laser polarization direction, and as a function of the laser polarization direction at a fixed scattering angle

Glide path preparation in S-shaped canals with rotary pathfinding nickel-titanium instruments.

Science.gov (United States)

Ajuz, Natasha C C; Armada, Luciana; Gonçalves, Lucio S; Debelian, Gilberto; Siqueira, José F

2013-04-01

This study compared the incidence of deviation along S-shaped (double-curved) canals after glide path preparation with 2 nickel-titanium (NiTi) rotary pathfinding instruments and hand K-files. S-shaped canals from 60 training blocks were filled with ink, and preinstrumentation images were obtained by using a stereomicroscope. Glide path preparation was performed by an endodontist who used hand stainless steel K-files (up to size 20), rotary NiTi PathFile instruments (up to size 19), or rotary NiTi Scout RaCe instruments (up to size 20). Postinstrumentation images were taken by using exactly the same conditions as for the preinstrumentation images, and both pictures were superimposed. Differences along the S-shaped canal for the mesial and distal aspects were measured to evaluate the occurrence of deviation. Intragroup analysis showed that all instruments promoted some deviation in virtually all levels. Overall, regardless of the group, deviations were observed in the mesial wall at the canal terminus and at levels 4, 5, 6 and 7 mm and in the distal wall at levels 1, 2, and 3 mm. These levels corresponded to the inner walls of each curvature. Both rotary NiTi instruments performed significantly better than hand K-files at all levels (P instruments showed significantly better results than PathFiles at levels 0, 2, 3, 5, and 6 mm (P rotary NiTi instruments are suitable for adequate glide path preparation because they promoted less deviation from the original canal anatomy when compared with hand-operated instruments. Of the 2 rotary pathfinding instruments, Scout RaCe showed an overall significantly better performance. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Micro-XRD and temperature-modulated DSC investigation of nickel-titanium rotary endodontic instruments.

Science.gov (United States)

Alapati, Satish B; Brantley, William A; Iijima, Masahiro; Schricker, Scott R; Nusstein, John M; Li, Uei-Ming; Svec, Timothy A

2009-10-01

Employ Micro-X-ray diffraction and temperature-modulated differential scanning calorimetry to investigate microstructural phases, phase transformations, and effects of heat treatment for rotary nickel-titanium instruments. Representative as-received and clinically used ProFile GT and ProTaper instruments were principally studied. Micro-XRD analyses (Cu Kalpha X-rays) were performed at 25 degrees C on areas of approximately 50 microm diameter near the tip and up to 9 mm from the tip. TMDSC analyses were performed from -80 to 100 degrees C and back to -80 degrees C on segments cut from instruments, using a linear heating and cooling rate of 2 degrees C/min, sinusoidal oscillation of 0.318 degrees C, and period of 60s. Instruments were also heat treated 15 min in a nitrogen atmosphere at 400, 500, 600 and 850 degrees C, and analyzed. At all Micro-XRD analysis regions the strongest peak occurred near 42 degrees , indicating that instruments were mostly austenite, with perhaps some R-phase and martensite. Tip and adjacent regions had smallest peak intensities, indicative of greater work hardening, and the intensity at other sites depended on the instrument. TMDSC heating and cooling curves had single peaks for transformations between martensite and austenite. Austenite-finish (A(f)) temperatures and enthalpy changes were similar for as-received and used instruments. Heat treatments at 400, 500 and 600 degrees C raised the A(f) temperature to 45-50 degrees C, and heat treatment at 850 degrees C caused drastic changes in transformation behavior. Micro-XRD provides novel information about NiTi phases at different positions on instruments. TMDSC indicates that heat treatment might yield instruments with substantial martensite and improved clinical performance.

The effect of multiple autoclave cycles on the surface of rotary nickel-titanium endodontic files: An in vitro atomic force microscopy investigation.

Science.gov (United States)

Nair, Ashish Shashikant; Tilakchand, Mahima; Naik, Balaram Damodar

2015-01-01

To observe and study the effect of multiple autoclave sterilization cycles, on the surface of nickel-titanium (NiTi) files. The file used for this study was the Mtwo file (VDW) and ProTaper (Dentsply). The apical 5 mm of the files were attached to a silicon wafer and subjected to autoclave cycles under standardized conditions. They were scanned with an AFM after 1, 5, and 10 cycles. The unsterilized files were used as control, before start of the study. Three vertical topographic parameters namely maximum height (MH), root mean square (RMS) of surface roughness, and arithmetic mean roughness (AMR)were measured with the atomic force microscope (AFM). Analysis of variance along with Tukey's test was used to test the differences. The vertical topographic parameters were higher for both the files, right after the first cycle, when compared with the control (P autoclave cycles, a fact that should be kept in mind during their reuse.

Nickel extraction from nickel matte

Science.gov (United States)

Subagja, R.

2018-01-01

In present work, the results of research activities to make nickel metal from nickel matte are presented. The research activities were covering a) nickel matte characterization using Inductively Couple plasma (ICP), Electron Probe Micro Analyzer (EPMA) and X-Ray Diffraction (XRD), b) nickel matte dissolution process to dissolve nickel from nickel matte into the spent electrolyte solutions that contains hydrochloric acid, c) purification of nickel chloride leach solution by copper cementation process to remove copper using nickel matte, selective precipitation process to remove iron, solvent extraction using Tri normal octyl amine to separate cobalt from nickel chloride solutions and d) Nickel electro winning process to precipitate nickel into the cathode surface from purified nickel chloride solution by using direct current. The research activities created 99, 72 % pure nickel metal as the final product of the process.

Effects of aging on the shape memory and superelasticity behavior of ultra-high strength Ni54Ti46 alloys under compression

International Nuclear Information System (INIS)

Kaya, I.; Tobe, H.; Karaca, H.E.; Basaran, B.; Nagasako, M.; Kainuma, R.; Chumlyakov, Y.

2016-01-01

This study investigates the effects of aging on the shape memory and superelasticity behavior of a Ni-rich Ni 54 Ti 46 (at%) alloy. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM) and compression test (thermal cycling under stress and superelasticity) were carried out after 3 h agin;g from 450 °C to 600 °C. The alloys show recoverable shape memory effect with transformation strains of about 1% and narrow hysteresis under high stress levels. The work output of 14.1 Jg −1 was observed at an ultra-high stress level of 1500 MPa after 600 °C 3 h aging. 450 °C 3 h aging resulted in a very narrow temperature hysteresis of 8°C under an ultra-high stress level of 1500 MPa. At room temperature, the superelastic response with 4% total strain was obtained even when high stress level of 2000 MPa is applied after 550 °C 3 h aging.

Comparison of dentinal damage induced by different nickel-titanium rotary instruments during canal preparation: An in vitro study.

Science.gov (United States)

Garg, Shiwani; Mahajan, Pardeep; Thaman, Deepa; Monga, Prashant

2015-01-01

To compare dentinal damage caused by hand and rotary nickel-titanium instruments using ProTaper, K3 Endo, and Easy RaCe systems after root canal preparation. One hundred and fifty freshly extracted mandibular premolars were randomly divided into five experimental groups of 30 teeth each and biomechanical preparation was done: Group 1 with unprepared teeth; Group 2 were prepared with hand files; Group 3 with ProTaper rotary instruments; Group 4 with K3 rotary; Group 5 with Easy RaCe rotary instruments. Then, roots were cut horizontally at 3, 6, and 9 mm from apex and were viewed under stereomicroscope. The presence of dentinal defects was noted. Groups were analyzed with the Chi-square test. Significant difference was seen between groups. No defects were found in unprepared roots and those prepared with hand files. ProTaper, K3 rotary, and Easy RaCe preparations resulted in dentinal defects in 23.3%, 10%, and 16.7% of teeth, respectively. More defects were shown in coronal and middle sections, and no defect was seen in apical third. The present study revealed that use of rotary instruments could result in an increased chance for dentinal defects as compared to hand instrumentation.

Cyclic Fatigue Resistance of Novel Rotary Files Manufactured from Different Thermal Treated Nickel-Titanium Wires in Artificial Canals.

Science.gov (United States)

Karataşlıoglu, E; Aydın, U; Yıldırım, C

2018-02-01

The aim of this in vitro study was to compare the static cyclic fatigue resistance of thermal treated rotary files with a conventional nickel-titanium (NiTi) rotary file. Four groups of 60 rotary files with similar file dimensions, geometries, and motion were selected. Groups were set as HyFlex Group [controlled memory wire (CM-Wire)], ProfileVortex Group (M-Wire), Twisted File Group (R-Phase Wire), and OneShape Group (conventional NiTi wire)] and tested using a custom-made static cyclic fatigue testing apparatus. The fracture time and fragment length of the each file was also recorded. Statistical analysis was performed using one-way analysis of variance and Tukey's test at the 95% confidence level (P = 0.05). The HyFlex group had a significantly higher mean cyclic fatigue resistance than the other three groups (P Wire alloy represented the best performance in cyclic fatigue resistance, and NiTi alloy in R-Phase had the second highest fatigue resistance. CM and R-Phase manufacturing technology processed to the conventional NiTi alloy enhance the cyclic fatigue resistance of files that have similar design and size. M-wire alloy did not show any superiority in cyclic fatigue resistance when compared with conventional NiTi wire.

An in vitro assessment of the physical properties of novel Hyflex nickel-titanium rotary instruments.

Science.gov (United States)

Peters, O A; Gluskin, A K; Weiss, R A; Han, J T

2012-11-01

To determine several properties including torsional and fatigue limits, as well as torque during canal preparation, of Hyflex, a rotary instrument manufactured from so-called controlled memory nickel-titanium alloy. The instruments were tested in vitro using a special torque bench that permits both stationary torque tests according to ISO3630-1 and fatigue limit determination, as well as measurement of torque (in Ncm) and apical force (in N) during canal preparation. Fatigue limit (in numbers of cycles to failure) was determined in a 90°, 5 mm radius block-and-rod assembly. Simulated canals in plastic blocks were prepared using both a manufacturer-recommended single-length technique as well as a generic crown-down approach. anova with Bonferroni post hoc procedures was used for statistical analysis. Torque at failure ranged from 0.47 to 1.38 Ncm, with significant differences between instrument sizes (P instruments size 20, .04 taper and size 25, .08 taper, respectively. Torque during canal preparation was significantly higher for small instruments used in the single-length technique but lower for the size 40, .04 taper, compared to a crown-down approach. No instrument fractured; 82% of the instruments used were plastically deformed; however, only 37% of these remained deformed after a sterilization cycle. Hyflex rotary instruments are bendable and flexible and have similar torsional resistance compared to instruments made of conventional NiTi. Fatigue resistance is much higher, and torque during preparation is less, compared to other rotary instruments tested previously under similar conditions. © 2012 International Endodontic Journal.

Characterization and coating stability evaluation of nickel-titanium orthodontic esthetic wires: an in vivo study.

Science.gov (United States)

Argalji, Nina; Silva, Eduardo Moreira da; Cury-Saramago, Adriana; Mattos, Claudia Trindade

2017-08-21

The objective of this study was to compare coating dimensions and surface characteristics of two different esthetic covered nickel-titanium orthodontic rectangular archwires, as-received from the manufacturer and after oral exposure. The study was designed for comparative purposes. Both archwires, as-received from the manufacturer, were observed using a stereomicroscope to measure coating thickness and inner metallic dimensions. The wires were also exposed to oral environment in 11 orthodontic active patients for 21 days. After removing the samples, stereomicroscopy images were captured, coating loss was measured and its percentage was calculated. Three segments of each wire (one as-received and two after oral exposure) were observed using scanning electron microscopy for a qualitative analysis of the labial surface of the wires. The Lilliefors test and independent t-test were applied to verify normality of data and statistical differences between wires, respectively. The significance level adopted was 0.05. The results showed that the differences between the wires while comparing inner height and thickness were statistically significant (p wire presented a coating thickness twice that of the control wire, which was also a statistically significant difference. The coating loss percentage was also statistically different (p = 0.0346) when the latest launched wire (13.27%) was compared to the control (29.63%). In conclusion, the coating of the most recent wire was thicker and more uniform, whereas the control had a thinner coating on the edges. After oral exposure, both tested wires presented coating loss, but the most recently launched wire exhibited better results.

Evaluation of the feasibility of joining titanium alloy to heavymet tungsten alloy

Energy Technology Data Exchange (ETDEWEB)

1978-06-07

Information is presented on a program to select and evaluate methods of brazing and/or explosively welding Ti-6Al-4V titanium alloy to Heavymet, a tungsten-base metal containing up to about 20% alloying elements (nickel, copper, etc.) to improve its ductility and other mechanical properties. Designs permitting the reliable production of joints between these base metals were of interest too. While this investigation was primarily concerned with an engineering study of the problems associated with joining these base metals in the required configuration, limited experimental studies were conducted also. The joining methods are reviewed individually. Recommendations for developing a viable titanium-tungsten joining procedure are discussed.

Evaluation of the feasibility of joining titanium alloy to heavymet tungsten alloy

International Nuclear Information System (INIS)

1978-01-01

Information is presented on a program to select and evaluate methods of brazing and/or explosively welding Ti-6Al-4V titanium alloy to Heavymet, a tungsten-base metal containing up to about 20% alloying elements (nickel, copper, etc.) to improve its ductility and other mechanical properties. Designs permitting the reliable production of joints between these base metals were of interest too. While this investigation was primarily concerned with an engineering study of the problems associated with joining these base metals in the required configuration, limited experimental studies were conducted also. The joining methods are reviewed individually. Recommendations for developing a viable titanium-tungsten joining procedure are discussed

Microscopic Features of Fractured Fragment of Nickel-Titanium Endodontic Instruments by Two Different Modes of Torsional Loading

Directory of Open Access Journals (Sweden)

Ibrahim H. Abu-Tahun

2018-01-01

Full Text Available This study compared the microscopic features of the fractured endodontic nickel-titanium (NiTi rotary instruments by two different torsional loadings: repetitive torsional loading (RTL and single torsional loading (STL based on the International Organization for Standardization (ISO. ProTaper Next, HyFlex EDM, and V-Taper 2 were compared in this study. In the STL method, the torsional load was applied after fixing the 3 mm tip of the file, by continuous clockwise rotation (2 rpm until fracture. In the RTL method, a preset rotational loading (0.5 N·cm was applied and the clockwise loading to the preset torque and counterclockwise unloading to original position were repeated at 50 rpm until the file fractured. Fractured fragments by two methods were compared under a scanning electron microscope (SEM to examine the topographic features of the fractured surfaces and longitudinal aspects. SEM examinations showed significantly different features according to the loading methods. Specimens from the RTL method showed ruptured aspects on cross sections, with multiple areas of initiated cracks while the STL method showed the typical features of torsional failure, such as circular abrasion marks and fatigue dimples. This study suggested a new repetitive torsional loading method which is much more clinically relevant and may result in a different fracture feature from STL method.

Torsional resistance of XP-endo Shaper at body temperature compared with several nickel-titanium rotary instruments.

Science.gov (United States)

Elnaghy, A M; Elsaka, S E

2018-05-01

To compare the torsional resistance of XP-endo Shaper (XPS; size 30, .01 taper, FKG Dentaire, La Chaux-de-Fonds, Switzerland) instruments at body temperature with TRUShape (TRS; size 30, .06 taper, Dentsply Tulsa Dental Specialties, Tulsa, OK, USA), ProFile Vortex (PV; size 30, .04 taper, Dentsply Tulsa Dental Specialties) and FlexMaster (FM; size 30, .04 taper, VDW GmbH, Munich, Germany) nickel-titanium rotary instruments. A metal block with a square-shaped mould (5 mm × 5 mm × 5 mm) was positioned inside a glass container. Five millimetres of the tip of each instrument was held inside the metal block by filling the mould with a resin composite. The instruments were tested for torsional resistance in saline solution at 37 °C. Data were analysed using one-way analysis of variance (anova) and Tukey post hoc tests. The significance level was set at P instruments tested (P instruments (P = 0.211). The ranking for torsional resistance values was: FM > PV > TRS > XPS. FlexMaster and ProFile Vortex instruments were more resistant to torsional stress compared with TRUShape and XP-endo Shaper instruments. The manufacturing process used to produce XP-endo Shaper instruments did not enhance their resistance to torsional stress as compared with the other instruments. © 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Synthesis and characterization of inorganic ion exchangers based on mixed oxide tin-titanium to be used in recovery of cadmium and nickel and photoluminescent studies

International Nuclear Information System (INIS)

Paganini, Paula Pinheiro

2007-01-01

This work presents the synthesis, characterization and adsorption studies of inorganic ion exchangers based on mixed tin-titanium oxide for recovery of cadmium and nickel metals from aqueous effluents, discarded in the environment mainly through Ni-Cd battery. The exchangers were synthesized by sol-gel modified method using a mixture of tin(IV) chloride and titanium(III) chloride and ammonium hydroxide, as precursors reagents. The materials obtained: SnO 2 /TiO 2 and SnO 2 /TiO 2 :Eu 3+ were characterized by infrared spectroscopy, thermal analysis, scattering electronic microscopy (SEM), X-ray powder diffraction (XRD) (powder method) and electronic spectroscopy (excitation and emission) for the europium doped exchanger. The same materials also were synthesized in polymeric matrix too and can be used in column, because the synthesized materials showed crystals size in nano metric scale. It was determined by the distribution ratios for metals taking as parameters the influence of pH, the concentration of metals (by adsorption isotherms) and the contact time (by adsorption kinetic). The inorganic ion exchanger presented high exchange capacity with adsorption percent above 90 por cent for the studied conditions, quickly kinetic, heterogeneous exchange surfaces, physic adsorption and spontaneous process of exchange. To the doped exchanger spectroscopy properties were studied and also it was calculated the intensity parameters and it was found a satisfactory quantum yield. (author)

Characterization of diffusion bonded joint between titanium and 304 stainless steel using a Ni interlayer

International Nuclear Information System (INIS)

Kundu, S.; Chatterjee, S.

2008-01-01

Solid-state diffusion bonded joints were prepared between commercially pure titanium and 304 stainless steel with nickel as an intermediate material in the temperature range of 800-950 deg. C for 10.8 ks under a 3 MPa uniaxial pressure in vacuum. The interface microstructures and reaction products of the transition joints were investigated by optical and scanning electron microscopy. Up to 850 deg. C processing temperature, a 300-μm nickel interlayer completely restricts the diffusion of titanium to stainless steel. However, the nickel interlayer cannot block the diffusion of Ti to the stainless side and λ + χ + α-Fe, λ + FeTi and λ + FeTi + β-Ti phase mixtures are formed at the SS-Ni interface, when bonding was processed at 900 deg. C and above. These reaction products were confirmed by X-ray diffraction. A maximum tensile strength of ∼ 270 MPa and shear strength of ∼ 194 MPa, along with 6.2% ductility, were obtained for the diffusion bonded joint processed at 850 deg. C. Fracture surface observation in SEM using EDS demonstrates that failure occurred through the Ni-Ti interface of the joints when processed up to 850 deg. C and through the SS-Ni interface when processed at and above 900 deg. C

Neutron diffraction investigation of hysteresis reduction and increase in linearity in the stress-strain response of superelastic NiTi

International Nuclear Information System (INIS)

Rathod, C.R.; Clausen, B.; Bourke, M.A.M.; Vaidyanathan, R.

2006-01-01

In situ neutron diffraction measurements during loading have been performed on plastically deformed superelastic NiTi samples. The measurements observed retained B19 ' phase in the unloaded state as a result of the plastic deformation in otherwise completely B2 phase samples. A reversible stress-induced B2-B19 ' transformation on application and removal of stress occurred in the presence of this retained B19 ' phase. The amount and orientation of this retained B19 ' phase changed with cycling. Such direct atomic scale observations in the bulk are used here for the first time to qualitatively elucidate the macroscopic stress-strain response in plastically deformed superelastic NiTi

Thermogravimetric study of reduction of oxides present in oxidized nickel-base alloy powders

Science.gov (United States)

Herbell, T. P.

1976-01-01

Carbon, hydrogen, and hydrogen plus carbon reduction of three oxidized nickel-base alloy powders (a solid solution strengthened alloy both with and without the gamma prime formers aluminum and titanium and the solid solution strengthened alloy NiCrAlY) were evaluated by thermogravimetry. Hydrogen and hydrogen plus carbon were completely effective in reducing an alloy containing chromium, columbium, tantalum, molybdenum, and tungsten. However, with aluminum and titanium present the reduction was limited to a weight loss of about 81 percent. Carbon alone was not effective in reducing any of the alloys, and none of the reducing conditions were effective for use with NiCrAlY.

Root Canal Transportation and Centering Ability of Nickel-Titanium Rotary Instruments in Mandibular Premolars Assessed Using Cone-Beam Computed Tomography.

Science.gov (United States)

Mamede-Neto, Iussif; Borges, Alvaro Henrique; Guedes, Orlando Aguirre; de Oliveira, Durvalino; Pedro, Fábio Luis Miranda; Estrela, Carlos

2017-01-01

The aim of this study was to evaluate, using cone-beam computed tomography (CBCT), transportation and centralization of different nickel-titanium (NiTi) rotary instruments. One hundred and twenty eight mandibular premolars were selected and instrumented using the following brands of NiTi files: WaveOne, WaveOne Gold, Reciproc, ProTaper Next, ProTaper Gold, Mtwo, BioRaCe and RaCe. CBCT imaging was performed before and after root canal preparation to obtain measurements of mesial and distal dentin walls and calculations of root canal transportation and centralization. A normal distribution of data was confirmed by the Kolmogorov-Smirnov and Levene tests, and results were assessed using the Kruskal-Wallis test. Statistical significance was set at 5%. ProTaper Gold produced the lowest canal transportation values, and RaCe, the highest. ProTaper Gold files also showed the highest values for centering ability, whereas BioRaCe showed the lowest. No significant differences were found across the different instruments in terms of canal transportation and centering ability (P > 0.05). Based on the methodology employed, all instruments used for root canal preparation of mandibular premolars performed similarly with regard to canal transportation and centering ability.

Impact of heat treatments on the fatigue resistance of different rotary nickel-titanium instruments.

Science.gov (United States)

Braga, Lígia Carolina Moreira; Faria Silva, Ana Cristina; Buono, Vicente Tadeu Lopes; de Azevedo Bahia, Maria Guiomar

2014-09-01

The aim of this study was to assess the influence of M-Wire (Dentsply Tulsa Dental Specialties, Tulsa, OK) and controlled memory technologies on the fatigue resistance of rotary nickel-titanium (NiTi) files by comparing files made using these 2 technologies with conventional NiTi files. Files with a similar cross-sectional design and diameter were chosen for the study: new 30/.06 files of the EndoWave (EW; J. Morita Corp, Osaka, Japan), HyFlex (HF; Coltene/Whaledent, Inc, Cuyahoga Falls, OH), ProFile Vortex (PV; Dentsply Tulsa Dental Specialties, Tulsa, OK), and Typhoon (TYP; Clinician's Choice Dental Products, New Milford, CT) systems together with ProTaper Universal F2 instruments (PTU F2; Dentsply Maillefer, Ballaigues, Switzerland). The compositions and transformation temperatures of the instruments were analyzed using x-ray energy-dispersive spectroscopy and differential scanning calorimetry, whereas the mean file diameter values at 3 mm from the tip (D3) were measured using image analysis software. The average number of cycles to failure was determined using a fatigue test device. X-ray energy-dispersive spectroscopy analysis showed that, on average, all the instruments exhibited the same chemical composition, namely, 51% Ni-49% Ti. The PV, TYP, and HF files exhibited increased transformation temperatures. The PTU F2, PV, and TYP files had similar D3 values, which were less than those of the EW and HF files. The average number of cycles to failure values were 150% higher for the TYP files compared with the PV files and 390% higher for the HF files compared with the EW files. M-Wire and controlled memory technologies increase the fatigue resistance of rotary NiTi files. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Size effect and scaling power-law for superelasticity in shape-memory alloys at the nanoscale.

Science.gov (United States)

Gómez-Cortés, Jose F; Nó, Maria L; López-Ferreño, Iñaki; Hernández-Saz, Jesús; Molina, Sergio I; Chuvilin, Andrey; San Juan, Jose M

2017-08-01

Shape-memory alloys capable of a superelastic stress-induced phase transformation and a high displacement actuation have promise for applications in micro-electromechanical systems for wearable healthcare and flexible electronic technologies. However, some of the fundamental aspects of their nanoscale behaviour remain unclear, including the question of whether the critical stress for the stress-induced martensitic transformation exhibits a size effect similar to that observed in confined plasticity. Here we provide evidence of a strong size effect on the critical stress that induces such a transformation with a threefold increase in the trigger stress in pillars milled on [001] L2 1 single crystals from a Cu-Al-Ni shape-memory alloy from 2 μm to 260 nm in diameter. A power-law size dependence of n = -2 is observed for the nanoscale superelasticity. Our observation is supported by the atomic lattice shearing and an elastic model for homogeneous martensite nucleation.

Creep deformation mechanisms in a γ titanium aluminide

Energy Technology Data Exchange (ETDEWEB)

Abdallah, Zakaria [Institute of Structural Materials, College of Engineering, Bay Campus, Swansea University, Swansea SA18EN (United Kingdom); Ding, Rengen [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B152TT (United Kingdom); Martin, Nigel; Dixon, Mark [Rolls-Royce plc, P.O. Box 31, Derby DE248BJ (United Kingdom); Bache, Martin [Institute of Structural Materials, College of Engineering, Bay Campus, Swansea University, Swansea SA18EN (United Kingdom)

2016-09-15

Titanium aluminides (TiAl) are considered as potential alternatives to replace nickel-based alloys of greater density for selected components within future gas turbine aero-engines. This is attributed to the high specific strength as well as the good oxidation resistance at elevated temperatures. The gamma (γ) titanium aluminide system Ti-45Al-2Mn-2Nb has previously demonstrated promising performance in terms of its physical and mechanical properties. The main aim of the current study, which is a continuation of a previously published paper, aims at evaluating the performance of this titanium aluminide system under high temperature creep conditions. Of particular interest, the paper is strongly demonstrating the precise capability of the Wilshire Equations technique in predicting the long-term creep behaviour of this alloy. Moreover, it presents a physically meaningful understanding of the various creep mechanisms expected under various testing conditions. To achieve this, two creep specimens, tested under distinctly different stress levels at 700 °C have been extensively examined. Detailed microstructural investigations and supporting transmission electron microscopy (TEM) have explored the differences in creep mechanisms active under the two stress regimes, with the deformation mechanisms correlated to Wilshire creep life prediction curves.

Comparative short-term in vitro analysis of mutans streptococci adhesion on esthetic, nickel-titanium, and stainless-steel arch wires.

Science.gov (United States)

Kim, In-Hye; Park, Hyo-Sang; Kim, Young Kyung; Kim, Kyo-Han; Kwon, Tae-Yub

2014-07-01

To test the hypothesis that there are no differences in mutans streptococci (MS) adhesion between esthetic and metallic orthodontic arch wires based on their surface characteristics. Surface roughness (Ra) and apparent surface free energy (SFE) were measured for six wires-four esthetic, one nickel-titanium (NiTi), and one stainless-steel (SS)-using profilometry and dynamic contact angle analysis, respectively. The amount of MS (Streptococcus mutans and Streptococcus sobrinus) adhering to the wires was quantified using the colony-counting method. The surfaces, coating layers, and MS adhesion were also observed by scanning electron microscopy. Statistical significance was set at P wires were significantly different from one another depending on the coating method (P wire showed the highest SFE, followed by the SS wire and then the four esthetic wires. The NiTi wires produced a significantly higher MS adhesion than did the SS wires (P wires showed significantly lower MS adhesions than did the NiTi wire (P < .05). Pearson correlation analyses found moderate significant positive correlations between the SFE and the S mutans and S sobrinus adhesions (r  =  .636/.427, P < .001/P  =  .001, respectively). The hypothesis is rejected. This study indicates that some esthetic coatings on NiTi alloy might reduce MS adhesion in vitro in the short term.

Orthodontic treatment with preadjusted appliances and low-friction ligatures: experimental evidence and clinical observations.

Science.gov (United States)

Baccetti, Tiziano; Franchi, Lorenzo; Fortini, Arturo

2008-01-01

To describe the features of low-friction ligatures during the leveling and aligning phase of fixed appliance therapy with preadjusted brackets. Experimental in vitro and in vivo studies were carried out to test the performance of the low-friction system with regard to leveling and aligning of the dental arches, as well as to increasing the transverse dimension of the maxillary arch. The outcomes of experimental testing showed that the combination of the low-friction ligatures with the superelastic nickel-titanium wires produced a significantly smaller amount of binding at the bracket/archwire/ligature unit when compared to conventional elastomeric ligatures. The biomechanical consequences of the use of low-friction ligatures were shorter duration of orthodontic treatment during the leveling and aligning phase, concurrent dentoalveolar expansion of the dental arch, and the possibility of using biologically adequate orthodontic forces.

Characterization and coating stability evaluation of nickel-titanium orthodontic esthetic wires: an in vivo study

Directory of Open Access Journals (Sweden)

Nina ARGALJI

2017-08-01

Full Text Available Abstract The objective of this study was to compare coating dimensions and surface characteristics of two different esthetic covered nickel-titanium orthodontic rectangular archwires, as-received from the manufacturer and after oral exposure. The study was designed for comparative purposes. Both archwires, as-received from the manufacturer, were observed using a stereomicroscope to measure coating thickness and inner metallic dimensions. The wires were also exposed to oral environment in 11 orthodontic active patients for 21 days. After removing the samples, stereomicroscopy images were captured, coating loss was measured and its percentage was calculated. Three segments of each wire (one as-received and two after oral exposure were observed using scanning electron microscopy for a qualitative analysis of the labial surface of the wires. The Lilliefors test and independent t-test were applied to verify normality of data and statistical differences between wires, respectively. The significance level adopted was 0.05. The results showed that the differences between the wires while comparing inner height and thickness were statistically significant (p < 0.0001. In average, the most recently launched wire presented a coating thickness twice that of the control wire, which was also a statistically significant difference. The coating loss percentage was also statistically different (p = 0.0346 when the latest launched wire (13.27% was compared to the control (29.63%. In conclusion, the coating of the most recent wire was thicker and more uniform, whereas the control had a thinner coating on the edges. After oral exposure, both tested wires presented coating loss, but the most recently launched wire exhibited better results.

Comparison of cyclic fatigue life of nickel-titanium files: an examination using high-speed camera

Directory of Open Access Journals (Sweden)

Taha Özyürek

2017-08-01

Full Text Available Objectives To determine the actual revolutions per minute (rpm values and compare the cyclic fatigue life of Reciproc (RPC, VDW GmbH, WaveOne (WO, Dentsply Maillefer, and TF Adaptive (TFA, Axis/SybronEndo nickel-titanium (NiTi file systems using high-speed camera. Materials and Methods Twenty RPC R25 (25/0.08, 20 WO Primary (25/0.08, and 20 TFA ML 1 (25/0.08 files were employed in the present study. The cyclic fatigue tests were performed using a dynamic cyclic fatigue testing device, which has an artificial stainless steel canal with a 60° angle of curvature and a 5-mm radius of curvature. The files were divided into 3 groups (group 1, RPC R25 [RPC]; group 2, WO Primary [WO]; group 3, TF Adaptive ML 1 [TFA]. All the instruments were rotated until fracture during the cyclic fatigue test and slow-motion videos were captured using high-speed camera. The number of cycles to failure (NCF was calculated. The data were analyzed statistically using one-way analysis of variance (ANOVA, p < 0.05. Results The slow-motion videos were indicated that rpm values of the RPC, WO, and TFA groups were 180, 210, and 425, respectively. RPC (3,464.45 ± 487.58 and WO (3,257.63 ± 556.39 groups had significantly longer cyclic fatigue life compared with TFA (1,634.46 ± 300.03 group (p < 0.05. There was no significant difference in the mean length of the fractured fragments. Conclusions Within the limitation of the present study, RPC and WO NiTi files showed significantly longer cyclic fatigue life than TFA NiTi file.

An innovative seismic bracing system based on a superelastic shape memory alloy ring

International Nuclear Information System (INIS)

Gao, Nan; Jeon, Jong-Su; DesRoches, Reginald; Hodgson, Darel E

2016-01-01

Shape memory alloys (SMAs) have great potential in seismic applications because of their remarkable superelasticity. Seismic bracing systems based on SMAs can mitigate the damage caused by earthquakes. The current study investigates a bracing system based on an SMA ring which is capable of both re-centering and energy dissipation. This lateral force resisting system is a cross-braced system consisting of an SMA ring and four tension-only cable assemblies, which can be applied to both new construction and seismic retrofit. The performance of this bracing system is examined through a quasi-static cyclic loading test and finite element (FE) analysis. This paper describes the experimental design in detail, discusses the experimental results, compares the performance with other bracing systems based on SMAs, and presents an Abaqus FE model calibrated on the basis of experimental results to simulate the superelastic behavior of the SMA ring. The experimental results indicate that the seismic performance of this system is promising in terms of damping and re-centering. The FE model can be used in the simulation of building structures using the proposed bracing system. (paper)

Microstructure, mechanical properties and superelasticity of biomedical porous NiTi alloy prepared by microwave sintering.

Science.gov (United States)

Xu, J L; Bao, L Z; Liu, A H; Jin, X J; Tong, Y X; Luo, J M; Zhong, Z C; Zheng, Y F

2015-01-01

Porous NiTi alloys were prepared by microwave sintering using ammonium hydrogen carbonate (NH4HCO3) as the space holder agent to adjust the porosity in the range of 22-62%. The effects of porosities on the microstructure, hardness, compressive strength, bending strength, elastic modulus, phase transformation temperature and superelasticity of the porous NiTi alloys were investigated. The results showed that the porosities and average pore sizes of the porous NiTi alloys increased with increasing the contents of NH4HCO3. The porous NiTi alloys consisted of nearly single NiTi phase, with a very small amount of two secondary phases (Ni3Ti, NiTi2) when the porosities are lower than 50%. The amount of Ni3Ti and NiTi2 phases increased with further increasing of the porosity proportion. The porosities had few effects on the phase transformation temperatures of the porous NiTi alloys. By increasing the porosities, all of the hardness, compressive strength, elastic modulus, bending strength and superelasticity of the porous NiTi alloys decreased. However, the compressive strength and bending strength were higher or close to those of natural bone and the elastic modulus was close to the natural bone. The superelastic recovery strain of the trained porous NiTi alloys could reach between 3.1 and 4.7% at the pre-strain of 5%, even if the porosity was up to 62%. Moreover, partial shape memory effect was observed for all porosity levels under the experiment conditions. Therefore, the microwave sintered porous NiTi alloys could be a promising candidate for bone implant. Copyright © 2014 Elsevier B.V. All rights reserved.

Effects of aging on the shape memory and superelasticity behavior of ultra-high strength Ni{sub 54}Ti{sub 46} alloys under compression

Energy Technology Data Exchange (ETDEWEB)

Kaya, I., E-mail: irfan_kaya@anadolu.edu.tr [Department of Mechanical Engineering, Faculty of Engineering, Anadolu University, Eskisehir TR 26555 (Turkey); Tobe, H.; Karaca, H.E. [Department of Mechanical Engineering, University of Kentucky, Lexington, KY 40506 (United States); Basaran, B. [Department of Engineering Technology, College of Technology, University of Houston, Houston, TX 77204 (United States); Nagasako, M. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Kainuma, R. [Department of Material Science, Tohoku University, Sendai 980-8579 (Japan); Chumlyakov, Y. [Siberian Physical-Technical Institute at Tomsk State University, Tomsk 634050 (Russian Federation)

2016-12-15

This study investigates the effects of aging on the shape memory and superelasticity behavior of a Ni-rich Ni{sub 54}Ti{sub 46} (at%) alloy. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM) and compression test (thermal cycling under stress and superelasticity) were carried out after 3 h agin;g from 450 °C to 600 °C. The alloys show recoverable shape memory effect with transformation strains of about 1% and narrow hysteresis under high stress levels. The work output of 14.1 Jg{sup −1} was observed at an ultra-high stress level of 1500 MPa after 600 °C 3 h aging. 450 °C 3 h aging resulted in a very narrow temperature hysteresis of 8°C under an ultra-high stress level of 1500 MPa. At room temperature, the superelastic response with 4% total strain was obtained even when high stress level of 2000 MPa is applied after 550 °C 3 h aging.

Effect of irrigation on surface roughness and fatigue resistance of controlled memory wire nickel-titanium instruments.

Science.gov (United States)

Cai, J-J; Tang, X-N; Ge, J-Y

2017-07-01

To investigate the effect of irrigation on the surface roughness and fatigue resistance of HyFlex and M3 controlled memory (CM) wire nickel-titanium instruments. Two new files of each brand were analysed by atomic force microscopy (AFM). Then, the instruments were dynamically immersed in either 5.25% sodium hypochlorite (NaOCl) or 17% ethylene diamine tetraacetic acid (EDTA) solution for 10 min, followed by AFM analysis. The roughness average (Ra) and root mean square (RMS) values were analysed statistically using an independent sample t-test. Then, 36 files of each brand were randomly assigned to three groups (n = 12). Group 1 (the control group) was composed of new instruments. Groups 2 and 3 were dynamically immersed in 5.25% NaOCl and 17% EDTA solutions for 10 min, respectively. The number of rotations to failure for various groups was analysed using the one-way analysis of variance software. For M3 files, the Ra and RMS values significantly increased (P  0.05) NaOCl. The resistance to cyclic fatigue of both HyFlex and M3 files did not significantly decrease (P > 0.05) by immersing in 5.25% NaOCl and 17% EDTA solutions. Except the HyFlex files immersed in NaOCl, the surface roughness of other files exposed to irrigants increased. However, a change in the surface tomography of CM wire instruments caused by contact with irrigants for 10 min did not trigger a decrease in cyclic fatigue resistance. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Improving the antimicrobial properties of titanium condenser material by surface modification using nanotechnology

International Nuclear Information System (INIS)

George, Rani P.; Dash, S.; Krishnan, R.; Kamruddin, M.; Kalavathi, S.; Tyagi, A.K.; Manoharan, N.; Dayal, R.K.; Vishwakarma, Vinita; Theresa, Josephine

2008-01-01

Biofouling is one of the major problems faced by condenser materials of power plants using seawater for cooling. Fouling control strategies in condensers include a combination of mechanical and chemical treatments like sponge ball cleaning, back washing and chlorination. In general, numerous studies have shown that no routine treatment regime can successfully keep the condenser tube clean over a period extending to years. Surface properties of the substratum influence initial adhesion and growth of bacterial cells on materials, modification of the surface for mitigating microbial attachment is the need of the hour. Metal nanoparticles are known to exhibit enhanced physical and chemical properties when compared to their bulk counter parts because of their high surface to volume ratios. Metals like copper are very toxic to microorganisms and effectively kill most of the microbes by blocking the respiratory enzyme. Copper alloys with their excellent resistance to biofouling are used extensively for marine applications. However, they are prone to localized corrosion initiation and consequently are getting replaced by extremely corrosion resistant titanium. Still, the inertness and biocompatibility of titanium makes it very susceptible to biofouling. Hence, this study attempts to use nano technology methods of surface modification of titanium using thin film of copper and also multilayers and bilayers of copper and nickel. This is aimed at improving the antimicrobial properties of this condenser pipe material. These nano structured thin films have been grown on titanium substrate using pulsed DC magnetron-sputtering and pulsed laser deposition. The thin films were characterized using Atomic Force Microscopy (AFM), Glancing Incidence X-ray Diffraction (GIXRD) and scanning electron microscopy (SEM with EDAX analysis). Antimicrobial properties were evaluated by exposure studies in seawater and bacterial cultures and by post exposure analysis using culture and

Urine nickel concentrations in nickel-exposed workers.

Science.gov (United States)

Bernacki, E J; Parsons, G E; Roy, B R; Mikac-Devic, M; Kennedy, C D; Sunderman, F W

1978-01-01

Electrothermal atomic absorption spectrometry was employed for analyses of nickel concentrations in urine samples from nickel-exposed workers in 10 occupational groups and from non-exposed workers in two control groups. Mean concentrations of nickel in urine were greatest in workers who were exposed to inhalation of aerosols of soluble nickel salts (e.g., workers in nickel plating operations and in an electrolytic nickel refinery). Less marked increases in urine nickel concentrations were found in groups of metal sprayers, nickel battery workers, bench mechanics and are welders. No significant increases in mean concentrations of nickel were found in urine samples from workers who performed grinding, buffing and polishing of nickel-containing alloys or workers in a coal gasification plant who employed Raney nickel as a hydrogenation catalyst. Measurements of nickel concentrations in urine are more sensitive and practical than measurements of serum nickel concentrations for evaluation of nickel exposures in industrial workers.

A review on nickel-free nitrogen containing austenitic stainless steels for biomedical applications.

Science.gov (United States)

Talha, Mohd; Behera, C K; Sinha, O P

2013-10-01

The field of biomaterials has become a vital area, as these materials can enhance the quality and longevity of human life. Metallic materials are often used as biomaterials to replace structural components of the human body. Stainless steels, cobalt-chromium alloys, commercially pure titanium and its alloys are typical metallic biomaterials that are being used for implant devices. Stainless steels have been widely used as biomaterials because of their very low cost as compared to other metallic materials, good mechanical and corrosion resistant properties and adequate biocompatibility. However, the adverse effects of nickel ions being released into the human body have promoted the development of "nickel-free nitrogen containing austenitic stainless steels" for medical applications. Nitrogen not only replaces nickel for austenitic structure stability but also much improves steel properties. Here we review the harmful effects associated with nickel and emphatically the advantages of nitrogen in stainless steel, as well as the development of nickel-free nitrogen containing stainless steels for medical applications. By combining the benefits of stable austenitic structure, high strength, better corrosion and wear resistance and superior biocompatibility in comparison to the currently used austenitic stainless steel (e.g. 316L), the newly developed nickel-free high nitrogen austenitic stainless steel is a reliable substitute for the conventionally used medical stainless steels. Copyright © 2013 Elsevier B.V. All rights reserved.

Does airborne nickel exposure induce nickel sensitization?

Science.gov (United States)

Mann, Eugen; Ranft, Ulrich; Eberwein, Georg; Gladtke, Dieter; Sugiri, Dorothee; Behrendt, Heidrun; Ring, Johannes; Schäfer, Torsten; Begerow, Jutta; Wittsiepe, Jürgen; Krämer, Ursula; Wilhelm, Michael

2010-06-01

Nickel is one of the most prevalent causes of contact allergy in the general population. This study focuses on human exposure to airborne nickel and its potential to induce allergic sensitization. The study group consisted of 309 children at school-starter age living in the West of Germany in the vicinity of two industrial sources and in a rural town without nearby point sources of nickel. An exposure assessment of nickel in ambient air was available for children in the Ruhr district using routinely monitored ambient air quality data and dispersion modelling. Internal nickel exposure was assessed by nickel concentrations in morning urine samples of the children. The observed nickel sensitization prevalence rates varied between 12.6% and 30.7%. Statistically significant associations were showed between exposure to nickel in ambient air and urinary nickel concentration as well as between urinary nickel concentration and nickel sensitization. Furthermore, an elevated prevalence of nickel sensitization was associated with exposure to increased nickel concentrations in ambient air. The observed associations support the assumption that inhaled nickel in ambient air might be a risk factor for nickel sensitization; further studies in larger collectives are necessary.

Thermal Neutron Capture and Thermal Neutron Burn-up of K isomeric state of 177mLu: a way to the Neutron Super-Elastic Scattering cross section

International Nuclear Information System (INIS)

Roig, O.; Belier, G.; Meot, V.; Daugas, J.-M.; Romain, P.; Aupiais, J.; Jutier, Ch.; Le Petit, G.; Letourneau, A.; Marie, F.; Veyssiere, Ch.

2006-01-01

Thermal neutron radiative capture and burn-up measurements of the K isomeric state in 177Lu form part of an original method to indirectly obtain the neutron super-elastic scattering cross section at thermal energy. Neutron super-elastic scattering, also called neutron inelastic acceleration, occurs during the neutron collisions with an excited nuclear level. In this reaction, the nucleus could partly transfer its excitation energy to the scattered neutron

Hyperbolically Patterned 3D Graphene Metamaterial with Negative Poisson's Ratio and Superelasticity.

Science.gov (United States)

Zhang, Qiangqiang; Xu, Xiang; Lin, Dong; Chen, Wenli; Xiong, Guoping; Yu, Yikang; Fisher, Timothy S; Li, Hui

2016-03-16

A hyperbolically patterned 3D graphene metamaterial (GM) with negative Poisson's ratio and superelasticity is highlighted. It is synthesized by a modified hydrothermal approach and subsequent oriented freeze-casting strategy. GM presents a tunable Poisson's ratio by adjusting the structural porosity, macroscopic aspect ratio (L/D), and freeze-casting conditions. Such a GM suggests promising applications as soft actuators, sensors, robust shock absorbers, and environmental remediation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of a flexible nanocomposite TiO{sub 2} film as a protective coating for bioapplications of superelastic NiTi alloys

Energy Technology Data Exchange (ETDEWEB)

Aun, Diego Pinheiro, E-mail: diegoaun@yahoo.com.br [Department of Metallurgical and Materials Engineering, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, 30270-901 Belo Horizonte, MG (Brazil); Houmard, Manuel, E-mail: mhoumard@ufmg.br [Department of Materials and Construction Engineering, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, 30270-901 Belo Horizonte, MG (Brazil); Mermoux, Michel, E-mail: michel.mermoux@lepmi.grenoble-inp.fr [LEPMI, Grenoble INP, rue de la Piscine—BP75 38402, Saint Martin d' Hères (France); Latu-Romain, Laurence, E-mail: laurence.latu-romain@simap.grenoble-inp.fr [SIR Team, Science et Ingénierie des Matériaux et Procédés, Grenoble INP, 1130, rue de la Piscine—BP75 38402, Saint Martin d' Hères (France); Joud, Jean-Charles, E-mail: jean-charles.joud@grenoble-inp.fr [SIR Team, Science et Ingénierie des Matériaux et Procédés, Grenoble INP, 1130, rue de la Piscine—BP75 38402, Saint Martin d' Hères (France); Berthomé, Gregory, E-mail: gregory.berthome@simap.grenoble-inp.fr [SIR Team, Science et Ingénierie des Matériaux et Procédés, Grenoble INP, 1130, rue de la Piscine—BP75 38402, Saint Martin d' Hères (France); Buono, Vicente Tadeu Lopes, E-mail: vbuono@demet.ufmg.br [Department of Metallurgical and Materials Engineering, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, 30270-901 Belo Horizonte, MG (Brazil)

2016-07-01

Highlights: • A NiTi alloy was coated with a flexible TiO{sub 2} protective layer via the sol–gel method. • Maximum flexibility was obtained with a nanocomposite crystalline/amorphous film. • The film reduces the Ni surface content, possibly improving the biocompatibility. - Abstract: An experimental procedure to coat superelastic NiTi alloys with flexible TiO{sub 2} protective nanocomposite films using sol–gel technology was developed in this work to improve the metal biocompatibility without deteriorating its superelastic mechanical properties. The coatings were characterized by scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and glazing incidence X-ray diffraction. The elasticity of the film was tested in coated specimens submitted to three-point bending tests. A short densification by thermal treatment at 500 °C for 10 min yielded a bilayer film consisting of a 50 nm-thick crystallized TiO{sub 2} at the inner interface with another 50-nm-thick amorphous oxide film at the outer interface. This bilayer could sustain over 6.4% strain without cracking and could thus be used to coat biomedical instruments as well as other devices made with superelastic NiTi alloys.

Electroless nickel plating on abs plastics from nickel chloride and nickel sulfate baths

International Nuclear Information System (INIS)

Inam-ul-haque; Ahmad, S.; Khan, A.

2005-01-01

Aqueous acid nickel chloride and alkaline nickel sulphate bath were studied for electroless nickel planting on acrylonitrile-butadiene-styrene (ABS) plastic. Before electroless nickel plating, specimens were etched, sensitized and activated. Effects of sodium hypophosphite and sodium citrate concentration on the electroless nickel plating thickness were discussed. Aqueous acid nickel chloride bath comprising, nickel chloride 10 g/L, sodium hypophosphite 40 g/L, sodium citrate 40g/L at pH 5.5, temperature 85 deg. C and density of 1 Be/ for thirty minutes gave best coating thickness in micrometer. It was found that acid nickel chloride bath had a greater stability, wide operating range and better coating thickness results than alkaline nickel sulphate bath. Acid nickel chloride bath gave better coating thickness than alkaline nickel sulfate bath

Physics-based simulation modeling and optimization of microstructural changes induced by machining and selective laser melting processes in titanium and nickel based alloys

Science.gov (United States)

Arisoy, Yigit Muzaffer

Manufacturing processes may significantly affect the quality of resultant surfaces and structural integrity of the metal end products. Controlling manufacturing process induced changes to the product's surface integrity may improve the fatigue life and overall reliability of the end product. The goal of this study is to model the phenomena that result in microstructural alterations and improve the surface integrity of the manufactured parts by utilizing physics-based process simulations and other computational methods. Two different (both conventional and advanced) manufacturing processes; i.e. machining of Titanium and Nickel-based alloys and selective laser melting of Nickel-based powder alloys are studied. 3D Finite Element (FE) process simulations are developed and experimental data that validates these process simulation models are generated to compare against predictions. Computational process modeling and optimization have been performed for machining induced microstructure that includes; i) predicting recrystallization and grain size using FE simulations and the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model, ii) predicting microhardness using non-linear regression models and the Random Forests method, and iii) multi-objective machining optimization for minimizing microstructural changes. Experimental analysis and computational process modeling of selective laser melting have been also conducted including; i) microstructural analysis of grain sizes and growth directions using SEM imaging and machine learning algorithms, ii) analysis of thermal imaging for spattering, heating/cooling rates and meltpool size, iii) predicting thermal field, meltpool size, and growth directions via thermal gradients using 3D FE simulations, iv) predicting localized solidification using the Phase Field method. These computational process models and predictive models, once utilized by industry to optimize process parameters, have the ultimate potential to improve performance of

Nickel Dermatitis - Nickel Excretion

DEFF Research Database (Denmark)

Menné, T.; Thorboe, A.

1976-01-01

Nickel excretion in urine in four females -sensitive to nickel with an intermittent dyshidrotic eruption was measured with flameless atomic absorption. Excretion of nickel was found to be increased in association with outbreaks of vesicles. The results support the idea that the chronic condition ...

STUDY OF THERMAL BEHAVIOUR ON TITANIUM ALLOYS (TI-6AL-4V

Directory of Open Access Journals (Sweden)

VASUDEVAN D

2017-08-01

Full Text Available Titanium is recognized for its strategic importance as a unique lightweight, high strength alloyed structurally efficient metal for critical, high-performance aircraft, such as jet engine and airframe components. Titanium is called as the "space age metal" and is recognized for its high strength-to-weight ratio. Today, titanium alloys are common, readily available engineered metals that compete directly with stainless steel and Specialty steels, copper alloys, nickel based alloys and composites. Titanium alloys are needed to be heat treated in order to reduce residual stress developed during fabrication and to increase the strength. Titanium (Ti-6Al-4V alloy is an alpha, beta alloy which is solution treated at a temperature of 950 ºC to attain beta phase. This beta phase is maintained by quenching and subsequent aging to increase strength. Thermal cycling process was carried out for Ti-6Al-4V specimens using forced air cooling. Heat treated titanium alloy specimen was used to carry out various tests before and after thermal cycling, The test, like tensile properties, co-efficient of thermal expansion, Microstructure, Compression test, Vickers Hardness was examined by the following test. Coefficient of Thermal expansion was measured using Dilatometer. Tensile test was carried out at room temperature using an Instron type machine. Vickers's hardness measurement was done on the same specimen as used for the microstructural observation from near the surface to the inside specimen. Compression test was carried out at room temperature using an Instron type machine. Ti‐6Al‐4V alloy is a workhorse of titanium industry; it accounts for about 60 percent of the total titanium alloy production. The high cost of titanium makes net shape manufacturing routes very attractive. Casting is a near net shape manufacturing route that offers significant cost advantages over forgings or complicated machined parts.

Vibrations Generated by Several Nickel-titanium Endodontic File Systems during Canal Shaping in an Ex Vivo Model.

Science.gov (United States)

Choi, Dong-Min; Kim, Jin-Woo; Park, Se-Hee; Cho, Kyung-Mo; Kwak, Sang Won; Kim, Hyeon-Cheol

2017-07-01

This study aimed to compare the vibration generated by several nickel-titanium (NiTi) file systems and transmitted to teeth under 2 different motions (continuous rotation motion and reciprocating motion). Sixty J-shaped resin blocks (Endo Training Bloc-J; Dentsply Maillefer, Ballaigues, Switzerland) were trimmed to a root-shaped form and divided into 2 groups according to the types of electric motors: WaveOne motor (WOM, Dentsply Maillefer) and X-Smart Plus motor (XSM, Dentsply Maillefer). Each group was further subdivided into 3 subgroups (n = 10 each) according to the designated file systems: ProTaper Next (PTN, Dentsply Maillefer), ProTaper Universal (PTU, Dentsply Maillefer), and WaveOne (WOP, Dentsply Maillefer) systems. Vibration was measured during the pecking motion using an accelerometer attached to a predetermined consistent position. The average vibration values were subjected to 2-way analysis of variance as well as the t test and Duncan test for post hoc comparison at the 95% confidence interval. Both motor types and instrument types produced significantly different ranges of average vibrations. Regardless of the instrument types, the WOM group generated greater vibration than the XSM group (P file system may generate greater vibration than the continuous rotation NiTi file systems. The motor type also has a significant effect to amplify the vibrations. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

In-vitro Assessing the Shaping Ability of Three Nickel-Titanium Rotary Single File Systems by Cone Beam Computed Tomography

Directory of Open Access Journals (Sweden)

Ali Imad Al-Asadi

2018-02-01

Full Text Available Aim of the study was to evaluate the canal transportation and centering ability of three nickel-titanium single file rotary systems by cone beam computed tomography (CBCT. Materials and methods: Thirty permanent maxillary first molar with a range of mesiobuccal canals curvature from 20-30 degree were selected and assigned into three groups (n=10, according to the biomechanical preparation system used: Hyflex EDM (HF, Reciproc blue (RB and OneShape (OS. The sampled were scanned by CBCT after being mounted on customized acrylic base and then rescanned after the instrumentation. Slices from the axial section were taken from both exposures at 3 mm, 6 mm and 9 mm from the root apex corresponding to the apical, middle, and coronal third respectively. Data were statistically analyzed using Kurskal-Wallis and Mann-Whitney U tests at the 5% confidence level. Results: The results showed that there were no significant differences at the apical and coronal third and a significant difference at the middle third regarding canal transportation. However, there was a significant difference at the apical third and no significant difference at the middle and coronal third regarding centering ratio. Conclusion: It was concluded that the three single rotary systems reported a degree in canal transportation and centric ratio but the Hyflex EDM reported the least one.

Cyclic fatigue resistance tests of Nickel-Titanium rotary files using simulated canal and weight loading conditions

Directory of Open Access Journals (Sweden)

Ok-In Cho

2013-02-01

Full Text Available Objectives This study compared the cyclic fatigue resistance of nickel-titanium (NiTi files obtained in a conventional test using a simulated canal with a newly developed method that allows the application of constant fatigue load conditions. Materials and Methods ProFile and K3 files of #25/.06, #30/.06, and #40/.04 were selected. Two types of testing devices were built to test their fatigue performance. The first (conventional device prescribed curvature inside a simulated canal (C-test, the second new device exerted a constant load (L-test whilst allowing any resulting curvature. Ten new instruments of each size and brand were tested with each device. The files were rotated until fracture and the number of cycles to failure (NCF was determined. The NCF were subjected to one-way ANOVA and Duncan's post-hoc test for each method. Spearman's rank correlation coefficient was computed to examine any association between methods. Results Spearman's rank correlation coefficient (ρ = -0.905 showed a significant negative correlation between methods. Groups with significant difference after the L-test divided into 4 clusters, whilst the C-test gave just 2 clusters. From the L-test, considering the negative correlation of NCF, K3 gave a significantly lower fatigue resistance than ProFile as in the C-test. K3 #30/.06 showed a lower fatigue resistance than K3 #25/.06, which was not found by the C-test. Variation in fatigue test methodology resulted in different cyclic fatigue resistance rankings for various NiTi files. Conclusions The new methodology standardized the load during fatigue testing, allowing determination fatigue behavior under constant load conditions.

Comparison of two techniques for assessing the shaping efficacy of repeatedly used nickel-titanium rotary instruments.

Science.gov (United States)

Ounsi, Hani F; Franciosi, Giovanni; Paragliola, Raffaele; Al-Hezaimi, Khalid; Salameh, Ziad; Tay, Franklin R; Ferrari, Marco; Grandini, Simone

2011-06-01

The shaping capacity of nickel-titanium (NiTi) rotary instruments is often assessed by photographic or micro-computed tomography (micro-CT) measurements, and these instruments are often used more than once clinically. This study was conducted to compare photographic and micro-CT measurements and to assess if the repeated use of NiTi instruments affected the shape of canal preparation. Ten new sets of ProTaper Universal instruments (Dentsply-Maillefer, Ballaigues, Switzerland) were used in 60 resin blocks simulating curved root canals. Groups 1 to 6 (n=10) represented the first to sixth use of the instrument, respectively. Digitized images of the prepared blocks were taken in both mesiodistal (MD) and buccolingual (BL) directions and area measurements (mm(2)) were calculated using AutoCAD (Autodesk Inc, San Rafael, CA). The volumes of the same prepared canals were measured using micro-CT (mm(3)). Statistical analysis was performed to detect differences between photographic and volumetric measurements and differences between uses. Two-way repeated-measures analysis of variance revealed significant differences between groups (P < .001). Regarding measurement type, there were no significant differences between BL and MD measurements, but there were significant differences between micro-CT and BL measurements (P < .001) and micro-CT and MD measurements (P=.001). Significant differences were also noted between uses. Within the limitations of the present study, micro-CT scanning is more discriminative of the changes in canal space associated with repeated instrument use than photographic measurements. Canal preparations are significantly smaller after the third use of the same instrument. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Reduction in bacterial counts in infected root canals after rotary or hand nickel-titanium instrumentation--a clinical study.

Science.gov (United States)

Rôças, I N; Lima, K C; Siqueira, J F

2013-07-01

To compare the antibacterial efficacy of two instrumentation techniques, one using hand nickel-titanium (NiTi) instruments and the other using rotary NiTi instruments, in root canals of teeth with apical periodontitis. Root canals from single-rooted teeth were instrumented using either hand NiTi instruments in the alternated rotation motion technique or rotary BioRaCe instruments. The irrigant used in both groups was 2.5% NaOCl. DNA extracts from samples taken before and after instrumentation were subjected to quantitative analysis by real-time polymerase chain reaction (qPCR). Qualitative analysis was also performed using presence/absence data from culture and qPCR assays. Bacteria were detected in all S1 samples by both methods. In culture analysis, 45% and 35% of the canals were still positive for bacterial presence after hand and rotary NiTi instrumentation, respectively (P > 0.05). Rotary NiTi instrumentation resulted in significantly fewer qPCR-positive cases (60%) than hand NiTi instrumentation (95%) (P = 0.01). Intergroup comparison of quantitative data showed no significant difference between the two techniques. There was no significant difference in bacterial reduction in infected canals after instrumentation using hand or rotary NiTi instruments. In terms of incidence of positive results for bacteria, culture also showed no significant differences between the groups, but the rotary NiTi instrumentation resulted in more negative results in the more sensitive qPCR analysis. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Experimental evaluation on the influence of autoclave sterilization on the cyclic fatigue of new nickel-titanium rotary instruments.

Science.gov (United States)

Plotino, Gianluca; Costanzo, Alberto; Grande, Nicola M; Petrovic, Renata; Testarelli, Luca; Gambarini, Gianluca

2012-02-01

The purpose of this study was to evaluate the effect of autoclave sterilization on cyclic fatigue resistance of rotary endodontic instruments made of traditional and new nickel-titanium (NiTi) alloys. Four NiTi rotary endodontic instruments of the same size (tip diameter 0.40 mm and constant .04 taper) were selected: K3, Mtwo, Vortex, and K3 XF prototypes. Each group was then divided into 2 subgroups, unsterilized instruments and sterilized instruments. The sterilized instruments were subjected to 10 cycles of autoclave sterilization. Twelve files from each different subgroup were tested for cyclic fatigue resistance. Means and standard deviations of number of cycles to failure (NCF) and fragment length of the fractured tip were calculated for each group, and data were statistically analyzed (P instruments for each type of file, differences were statistically significant (P instruments did not show significant differences (P > .05) in the mean NCF as a result of sterilization cycles (K3, 424 versus 439 NCF; Mtwo, 409 versus 419 NCF; Vortex, 454 versus 480 NCF). Comparing the results among the different groups, K3 XF (either sterilized or not) showed a mean NCF significantly higher than all other files (P endodontic instruments except for the K3 XF prototypes of rotary instruments that demonstrated a significant increase of cyclic fatigue resistance. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

The effect of titanium nickel nitride decorated carbon nanotubes-reduced graphene oxide hybrid support for methanol oxidation

Energy Technology Data Exchange (ETDEWEB)

Liu, Gen [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Pan, Zhanchang, E-mail: panzhanchang@163.com [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Li, Wuyi; Yu, Ke [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Xia, Guowei; Zhao, Qixiang; Shi, Shikun [Victory Giant Technology (Hui Zhou) Co., Ltd., Huizhou 516083 (China); Hu, Guanghui; Xiao, Chumin; Wei, Zhigang [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China)

2017-07-15

Highlights: • TiNiN/CNT-rGO support with an interactive three-dimensional structure and high surface area was synthesized. • Pt nanoparticles with small size were well dispersed on TiNiN/CNT-rGO support. • Pt/TiNiN/CNT-rGO shows remarkably enhanced methanol oxidation activity and durability. - Abstract: Titanium nickel nitride (TiNiN) decorated three-dimensional (3D) carbon nanotubes-reduced graphene oxide (CNT-rGO), a fancy 3D platinum (Pt)-based catalyst hybrid support, is prepared by a solvothermal process followed by a nitriding process, which is tested as anodic catalyst support for the methanol oxidation reaction (MOR). The structure, morphology and composition of the synthesized TiNiN/CNT-rGO exhibits a uniform particle dispersion with high purity and interpenetrating 3D network structure. Notably, Pt/TiNiN/CNT-rGO catalyst exhibits significantly improved catalytic activity and durability for methanol oxidation in comparison with Pt/CNT-rGO and conventional Pt/C (JM). The outstanding electrochemical performance was attributed to structure and properties. That is, the 3D CNT-rGO provided a fast transport network for charge-transfer and mass-transfer as well as TiNiN NPs with good synergistic effect and the strong electronic coupling between different domains in TiNiN/CNT-rGO, thus the catalytic activity of the novel catalyst is greatly improved. These results evidences 3D TiNiN/CNT-rGO as a promising catalyst support for a wide range of applications in fuel cells.

The effect of titanium nickel nitride decorated carbon nanotubes-reduced graphene oxide hybrid support for methanol oxidation

International Nuclear Information System (INIS)

Liu, Gen; Pan, Zhanchang; Li, Wuyi; Yu, Ke; Xia, Guowei; Zhao, Qixiang; Shi, Shikun; Hu, Guanghui; Xiao, Chumin; Wei, Zhigang

2017-01-01

Highlights: • TiNiN/CNT-rGO support with an interactive three-dimensional structure and high surface area was synthesized. • Pt nanoparticles with small size were well dispersed on TiNiN/CNT-rGO support. • Pt/TiNiN/CNT-rGO shows remarkably enhanced methanol oxidation activity and durability. - Abstract: Titanium nickel nitride (TiNiN) decorated three-dimensional (3D) carbon nanotubes-reduced graphene oxide (CNT-rGO), a fancy 3D platinum (Pt)-based catalyst hybrid support, is prepared by a solvothermal process followed by a nitriding process, which is tested as anodic catalyst support for the methanol oxidation reaction (MOR). The structure, morphology and composition of the synthesized TiNiN/CNT-rGO exhibits a uniform particle dispersion with high purity and interpenetrating 3D network structure. Notably, Pt/TiNiN/CNT-rGO catalyst exhibits significantly improved catalytic activity and durability for methanol oxidation in comparison with Pt/CNT-rGO and conventional Pt/C (JM). The outstanding electrochemical performance was attributed to structure and properties. That is, the 3D CNT-rGO provided a fast transport network for charge-transfer and mass-transfer as well as TiNiN NPs with good synergistic effect and the strong electronic coupling between different domains in TiNiN/CNT-rGO, thus the catalytic activity of the novel catalyst is greatly improved. These results evidences 3D TiNiN/CNT-rGO as a promising catalyst support for a wide range of applications in fuel cells.

Nickel titanium springs versus stainless steel springs: A randomized clinical trial of two methods of space closure.

Science.gov (United States)

Norman, Noraina Hafizan; Worthington, Helen; Chadwick, Stephen Mark

2016-09-01

To compare the clinical performance of nickel titanium (NiTi) versus stainless steel (SS) springs during orthodontic space closure. Two-centre parallel group randomized clinical trial. Orthodontic Department University of Manchester Dental Hospital and Orthodontic Department Countess of Chester Hospital, United Kingdom. Forty orthodontic patients requiring fixed appliance treatment were enrolled, each being randomly allocated into either NiTi (n = 19) or SS groups (n = 21). Study models were constructed at the start of the space closure phase (T0) and following the completion of space closure (T1). The rate of space closure achieved for each patient was calculated by taking an average measurement from the tip of the canine to the mesiobuccal groove on the first permanent molar of each quadrant. The study was terminated early due to time constraints. Only 30 patients completed, 15 in each study group. There was no statistically significant difference between the amounts of space closed (mean difference 0.17 mm (95%CI -0.99 to 1.34; P = 0.76)). The mean rate of space closure for NiTi coil springs was 0.58 mm/4 weeks (SD 0.24) and 0.85 mm/4 weeks (SD 0.36) for the stainless steel springs. There was a statistically significant difference between the two groups (P = 0.024), in favour of the stainless steel springs, when the mean values per patient were compared. Our study shows that stainless steel springs are clinically effective; these springs produce as much space closure as their more expensive rivals, the NiTi springs.

Review of corrosion phenomena on zirconium alloys, niobium, titanium, inconel, stainless steel, and nickel plate under irradiation

International Nuclear Information System (INIS)

Johnson, A.B. Jr.

1975-01-01

The role of nuclear fluxes in corrosion processes was investigated in ATR, ETR, PRTR, and in Hanford production reactors. Major effort was directed to zirconium alloy corrosion parameter studies. Corrosion and hydriding results are reported as a function of oxygen concentration in the coolant, flux level, alloy composition, surface pretreatment, and metallurgical condition. Localized corrosion and hydriding at sites of bonding to dissimilar metals are described. Corrosion behavior on specimens transferred from oxygenated to low-oxygen coolants in ETR and ATR experiments is compared. Mechanism studies suggest that a depression in the corrosion of the Zr--2.5Nb alloy under irradiation is due to radiation-induced aging. The radiation-induced onset of transition on several alloys is in general a gradual process which nucleates locally, causing areas of oxide prosity which eventually encompass the surface. Examination of Zry-2 process tubes reveals that accelerated corrosion has occurred in low-oxygen coolants. Hydrogen contents are relatively low, but show some localized profiles. Gross hydriding has occurred on process tubes containing aluminum spacers, apparently by a galvanic charging mechanism. Titanium paralleled Zry-2 in corrosion behavior under irradiation. Niobium corrosion was variable, but did not appear to be strongly influenced by radiation. Corrosion rates on Inconel and stainless steel were only slightly higher in-flux than out-of-reactor. Corrosion rates on nickel-plated aluminum appeared to vary substantially with preexposure treatments, but the rates generally were accelerated compared to rates on unirradiated coupons. (59 references, 11 tables, 12 figs.)

Effect of surface modification by nitrogen ion implantation on the electrochemical and cellular behaviors of super-elastic NiTi shape memory alloy.

Science.gov (United States)

Maleki-Ghaleh, H; Khalil-Allafi, J; Sadeghpour-Motlagh, M; Shakeri, M S; Masoudfar, S; Farrokhi, A; Beygi Khosrowshahi, Y; Nadernezhad, A; Siadati, M H; Javidi, M; Shakiba, M; Aghaie, E

2014-12-01

The aim of this investigation was to enhance the biological behavior of NiTi shape memory alloy while preserving its super-elastic behavior in order to facilitate its compatibility for application in human body. The surfaces of NiTi samples were bombarded by three different nitrogen doses. Small-angle X-ray diffraction was employed for evaluating the generated phases on the bombarded surfaces. The electrochemical behaviors of the bare and surface-modified NiTi samples were studied in simulated body fluid (SBF) using electrochemical impedance and potentio-dynamic polarization tests. Ni ion release during a 2-month period of service in the SBF environment was evaluated using atomic absorption spectrometry. The cellular behavior of nitrogen-modified samples was studied using fibroblast cells. Furthermore, the effect of surface modification on super-elasticity was investigated by tensile test. The results showed the improvement of both corrosion and biological behaviors of the modified NiTi samples. However, no significant change in the super-elasticity was observed. Samples modified at 1.4E18 ion cm(-2) showed the highest corrosion resistance and the lowest Ni ion release.

The effects of autoclave sterilization on the cyclic fatigue resistance of ProTaper Universal, ProTaper Next, and ProTaper Gold nickel-titanium instruments.

Science.gov (United States)

Özyürek, Taha; Yılmaz, Koray; Uslu, Gülşah

2017-11-01

It was aimed to compare the cyclic fatigue resistances of ProTaper Universal (PTU), ProTaper Next (PTN), and ProTaper Gold (PTG) and the effects of sterilization by autoclave on the cyclic fatigue life of nickel-titanium (NiTi) instruments. Eighty PTU, 80 PTN, and 80 PTG were included to the present study. Files were tested in a simulated canal. Each brand of the NiTi files were divided into 4 subgroups: group 1, as received condition; group 2, pre-sterilized instruments exposed to 10 times sterilization by autoclave; group 3, instruments tested were sterilized after being exposed to 25%, 50%, and 75% of the mean cycles to failure, then cycled fatigue test was performed; group 4, instruments exposed to the same experiment with group 3 without sterilization. The number of cycles to failure (NCF) was calculated. The data was statistically analyzed by using one-way analysis of variance and post hoc Tukey tests. PTG showed significantly higher NCF than PTU and PTN in group 1 ( p Autoclaving increased the cyclic fatigue resistances of PTN and PTG.

Titanium

Science.gov (United States)

Woodruff, Laurel G.; Bedinger, George M.; Piatak, Nadine M.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

2017-12-19

Titanium is a mineral commodity that is essential to the smooth functioning of modern industrial economies. Most of the titanium produced is refined into titanium dioxide, which has a high refractive index and is thus able to impart a durable white color to paint, paper, plastic, rubber, and wallboard. Because of their high strength-to-weight ratio and corrosion resistance, titanium metal and titanium metal alloys are used in the aerospace industry as well as for welding rod coatings, biological implants, and consumer goods.Ilmenite and rutile are currently the principal titanium-bearing ore minerals, although other minerals, including anatase, perovskite, and titanomagnetite, could have economic importance in the future. Ilmenite is currently being mined from two large magmatic deposits hosted in rocks of Proterozoic-age anorthosite plutonic suites. Most rutile and nearly one-half of the ilmenite produced are from heavy-mineral alluvial, fluvial, and eolian deposits. Titanium-bearing minerals occur in diverse geologic settings, but many of the known deposits are currently subeconomic for titanium because of complications related to the mineralogy or because of the presence of trace contaminants that can compromise the pigment production process.Global production of titanium minerals is currently dominated by Australia, Canada, Norway, and South Africa; additional amounts are produced in Brazil, India, Madagascar, Mozambique, Sierra Leone, and Sri Lanka. The United States accounts for about 4 percent of the total world production of titanium minerals and is heavily dependent on imports of titanium mineral concentrates to meet its domestic needs.Titanium occurs only in silicate or oxide minerals and never in sulfide minerals. Environmental considerations for titanium mining are related to waste rock disposal and the impact of trace constituents on water quality. Because titanium is generally inert in the environment, human health risks from titanium and titanium

Instability of cyclic superelastic deformation of NiTi investigated by synchrotron X-ray diffraction

Czech Academy of Sciences Publication Activity Database

Sedmák, P.; Šittner, Petr; Pilch, Jan; Curfs, C.

2015-01-01

Roč. 94, Aug (2015), s. 257-270 ISSN 1359-6454 R&D Projects: GA ČR GB14-36566G; GA ČR GPP108/12/P111; GA ČR GA14-15264S; GA ČR GAP107/12/0800 Institutional support: RVO:68378271 Keywords : shape memory alloy * NiTi * superelasticity * cyclic deformation * in situ X-ray diffraction Subject RIV: JG - Metallurgy Impact factor: 5.058, year: 2015

Fatigue performance of superelastic NiTi near stress-induced martensitic transformation

Czech Academy of Sciences Publication Activity Database

Alarcón Tarquino, Eduardo; Heller, Luděk; Chirani, S.A.; Šittner, Petr; Kopeček, Jaromír; Saint-Sulpice, L.; Calloch, S.

2017-01-01

Roč. 95, Feb (2017), s. 76-89 ISSN 0142-1123 R&D Projects: GA ČR GB14-36566G; GA MŠk LO1409; GA MŠk LM2015088; GA ČR GA16-20264S; GA ČR GA14-15264S Grant - others:FUNBIO(XE) CZ.2.16/3.1.00/21568 Institutional support: RVO:68378271 Keywords : shape-memory alloys * Nitinol * superelasticity * martensitic transformation * shape memory alloys * fatigue Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.899, year: 2016

Investigation of hydrogen evolution activity for the nickel, nickel-molybdenum nickel-graphite composite and nickel-reduced graphene oxide composite coatings

International Nuclear Information System (INIS)

Jinlong, Lv; Tongxiang, Liang; Chen, Wang

2016-01-01

Graphical abstract: - Highlights: • Improved HER efficiency of Ni-Mo coatings was attributed to ‘cauliflower’ like microstructure. • RGO in nickel-RGO composite coating promoted refined grain and facilitated HER. • Synergistic effect between nickel and RGO facilitated HER due to large specific surface of RGO. - Abstract: The nickel, nickel-molybdenum alloy, nickel-graphite and nickel-reduced graphene oxide composite coatings were obtained by the electrodeposition technique from a nickel sulfate bath. Nanocrystalline molybdenum, graphite and reduced graphene oxide in nickel coatings promoted hydrogen evolution reaction in 0.5 M H_2SO_4 solution at room temperature. However, the nickel-reduced graphene oxide composite coating exhibited the highest electrocatalytic activity for the hydrogen evolution reaction in 0.5 M H_2SO_4 solution at room temperature. A large number of gaps between ‘cauliflower’ like grains could decrease effective area for hydrogen evolution reaction in slight amorphous nickel-molybdenum alloy. The synergistic effect between nickel and reduced graphene oxide promoted hydrogen evolution, moreover, refined grain in nickel-reduced graphene oxide composite coating and large specific surface of reduced graphene oxide also facilitated hydrogen evolution reaction.

Investigation of hydrogen evolution activity for the nickel, nickel-molybdenum nickel-graphite composite and nickel-reduced graphene oxide composite coatings

Energy Technology Data Exchange (ETDEWEB)

Jinlong, Lv, E-mail: ljlbuaa@126.com [Beijing Key Laboratory of Fine Ceramics, Institute of Nuclear and New Energy Technology, Tsinghua University, Zhongguancun Street, Haidian District, Beijing 100084 (China); State Key Lab of New Ceramic and Fine Processing, Tsinghua University, Beijing 100084 (China); Tongxiang, Liang; Chen, Wang [Beijing Key Laboratory of Fine Ceramics, Institute of Nuclear and New Energy Technology, Tsinghua University, Zhongguancun Street, Haidian District, Beijing 100084 (China); State Key Lab of New Ceramic and Fine Processing, Tsinghua University, Beijing 100084 (China)

2016-03-15

Graphical abstract: - Highlights: • Improved HER efficiency of Ni-Mo coatings was attributed to ‘cauliflower’ like microstructure. • RGO in nickel-RGO composite coating promoted refined grain and facilitated HER. • Synergistic effect between nickel and RGO facilitated HER due to large specific surface of RGO. - Abstract: The nickel, nickel-molybdenum alloy, nickel-graphite and nickel-reduced graphene oxide composite coatings were obtained by the electrodeposition technique from a nickel sulfate bath. Nanocrystalline molybdenum, graphite and reduced graphene oxide in nickel coatings promoted hydrogen evolution reaction in 0.5 M H{sub 2}SO{sub 4} solution at room temperature. However, the nickel-reduced graphene oxide composite coating exhibited the highest electrocatalytic activity for the hydrogen evolution reaction in 0.5 M H{sub 2}SO{sub 4} solution at room temperature. A large number of gaps between ‘cauliflower’ like grains could decrease effective area for hydrogen evolution reaction in slight amorphous nickel-molybdenum alloy. The synergistic effect between nickel and reduced graphene oxide promoted hydrogen evolution, moreover, refined grain in nickel-reduced graphene oxide composite coating and large specific surface of reduced graphene oxide also facilitated hydrogen evolution reaction.

Diamondlike carbon coating as a galvanic corrosion barrier between dental implant abutments and nickel-chromium superstructures.

Science.gov (United States)

Ozkomur, Ahmet; Erbil, Mehmet; Akova, Tolga

2013-01-01

The objectives of this study were to evaluate the galvanic corrosion behavior between titanium and nickel-chromium (Ni-Cr) alloy, to investigate the effect of diamondlike carbon (DLC) coating over titanium on galvanic corrosion behavior between titanium and Ni-Cr alloy, and to evaluate the effect of DLC coating over titanium abutments on the fit and integrity of prosthetic assemblies by scanning electron microcopy (SEM). Five Ni-Cr and 10 titanium disks with a diameter of 5 mm and thickness of 3 mm were prepared. DLC coating was applied to five titanium disks. Electrode samples were prepared, and open circuit potential measurements, galvanic current measurements over platinum electrodes, and potentiodynamic polarization tests were carried out. For the SEM evaluation, 20 Ni-Cr alloy and 10 gold alloy superstructures were cast and prepared over 30 abutments. DLC coating was applied to 10 of the abutments. Following the fixation of prosthetic assemblies, the samples were embedded in acrylic resin and cross sectioned longitudinally. Internal fit evaluations were carried out through examination of the SEM images. Titanium showed more noble and electrochemically stable properties than Ni-Cr alloy. DLC coating over the cathode electrode served as an insulating film layer over the surface and prevented galvanic coupling. Results of the SEM evaluations indicated that the DLC-coated and titanium abutments showed no statistically significant difference in fit. Hence, no adverse effects on the adaptation of prosthetic components were found with the application of DLC coating over abutment surfaces. DLC coating might serve as a galvanic corrosion barrier between titanium abutments and Ni-Cr superstructures.

Finite element modeling of indentation-induced superelastic effect using a three-dimensional constitutive model for shape memory materials with plasticity

International Nuclear Information System (INIS)

Zhang, Yijun; Cheng, Yang-Tse; Grummon, David S.

2007-01-01

Indentation-induced shape memory and superelastic effects are recently discovered thermo-mechanical behaviors that may find important applications in many areas of science and engineering. Theoretical understanding of these phenomena is challenging because both martensitic phase transformation and slip plasticity exist under complex contact loading conditions. In this paper, we develop a three-dimensional constitutive model of shape memory alloys with plasticity. Spherical indentation-induced superelasticity in a NiTi shape memory alloy was simulated and compared to experimental results on load-displacement curves and recovery ratios. We show that shallow indents have complete recovery upon unloading, where the size of the phase transformation region is about two times the contact radius. Deep indents have only partial recovery when plastic deformation becomes more prevalent in the indent-affected zone

Endodontic shaping performance using nickel-titanium hand and motor ProTaper systems by novice dental students.

Science.gov (United States)

Tu, Ming-Gene; Chen, San-Yue; Huang, Heng-Li; Tsai, Chi-Cheng

2008-05-01

Preparing a continuous tapering conical shape and maintaining the original shape of a canal are obligatory in root canal preparation. The purpose of this study was to compare the shaping performance in simulated curved canal resin blocks of the same novice dental students using hand-prepared and engine-driven nickel-titanium (NiTi) rotary ProTaper instruments in an endodontic laboratory class. Twenty-three fourth-year dental students attending China Medical University Dental School prepared 46 simulated curved canals in resin blocks with two types of NiTi rotary systems: hand and motor ProTaper files. Composite images were prepared for estimation. Material removed, canal width and canal deviation were measured at five levels in the apical 4 mm of the simulated curved canals using AutoCAD 2004 software. Data were analyzed using Wilcoxon's rank-sum test. The hand ProTaper group cut significantly wider than the motor rotary ProTaper group in the outer wall, except for the apical 0 mm point. The total canal width was cut significantly larger in the hand group than in the motor group. There was no significant difference between the two groups in centering canal shape, except at the 3 mm level. These findings show that the novice students prepared the simulated curved canal that deviated more outwardly from apical 1 mm to 4 mm using the hand ProTaper. The ability to maintain the original curvature was better in the motor rotary ProTaper group than in the hand ProTaper group. Undergraduate students, if following the preparation sequence carefully, could successfully perform canal shaping by motor ProTaper files and achieve better root canal geometry than by using hand ProTaper files within the same teaching and practicing sessions.

Apical displacement produced by rotary nickel-titanium instruments and stainless steel files Deslocamento apical produzido por instrumentos de níquel-titânio acionados a motor e limas de aço inoxidável

Directory of Open Access Journals (Sweden)

José Roberto Vanni

2004-03-01

Full Text Available The aim of this study was to evaluate the apical displacement produced by different rotary nickel-titanium instruments, testing the hypothesis that rotary systems with nickel-titanium instruments produce lower mean values of apical displacement than stainless steel hand instruments. A total of 100 maxillary permanent first molars were selected for the study. The mesiobuccal roots were sectioned at the top cervical third and embedded in blocks of self-curing resin. The specimens were randomly divided into 5 groups and the root canals were prepared using the following nickel-titanium instruments: Group 1 - Quantec system 2000 (Analytic Endodontics, Mexico; Group 2 - Pro-File T.0.04 (Dentsply/Maillefer, Switzerland; Group 3 - Pro-File Series 29 T.0.04 (Dentsply Tulsa, Switzerland; Group 4 - Pow-R T.0.02 (Moyco-Union Broach, USA. Specimens in Group 5 were prepared using stainless steel hand instruments Flexofile (Dentsply/Maillefer, Switzerland. All root canals were previously submitted to cervical preparation using Orifice Shaper instruments #1, 2, 3 and 4 (Dentsply/Maillefer, Switzerland. After odontometry, the remaining root canal was shaped employing increasingly larger instruments, so that the final instrument corresponded to Quantec #9, Pro-File Series 29 #6, and #35 for the other groups. Specimens in Groups 1 to 4 were prepared using an electric handpiece with 16:1 reduction at 350 rpm. The specimens in Group 5 were manually prepared. Apical displacement was measured and recorded by means of radiographic superimposition on a specific desk. Statistical analysis (ANOVA of the results revealed that all groups presented apical displacements. Considering only the nickel-titanium instruments, Group 4 showed the lowest mean value while Groups 2 and 3 produced the highest mean apical displacement values (pO objetivo deste trabalho foi avaliar o deslocamento apical produzido por diferentes instrumentos de níquel-titânio acionadas a motor testando a

Dynamic Torque and Vertical Force Analysis during Nickel-titanium Rotary Root Canal Preparation with Different Modes of Reciprocal Rotation.

Science.gov (United States)

Tokita, Daisuke; Ebihara, Arata; Nishijo, Miki; Miyara, Kana; Okiji, Takashi

2017-10-01

The purpose of the present study was to compare 2 modes of reciprocal movement (torque-sensitive and time-dependent reciprocal rotation) with continuous rotation in terms of torque and apical force generation during nickel-titanium rotary root canal instrumentation. A custom-made automated root canal instrumentation and torque/force analyzing device was used to prepare simulated canals in resin blocks and monitor the torque and apical force generated in the blocks during preparation. Experimental groups (n = 7, each) consisted of (1) torque-sensitive reciprocal rotation with torque-sensitive vertical movement (group TqR), (2) time-dependent reciprocal rotation with time-dependent vertical movement (group TmR), and (3) continuous rotation with time-dependent vertical movement (group CR). The canals were instrumented with TF Adaptive SM1 and SM2 rotary files (SybronEndo, Orange, CA), and the torque and apical force were measured during instrumentation with SM2. The mean and maximum torque and apical force values were statistically analyzed using 1-way analysis of variance and the Tukey test (α = 0.05). The recordings showed intermittent increases of upward apical force and clockwise torque, indicating the generation and release of screw-in forces. The maximum upward apical force values in group TmR were significantly smaller than those in group CR (P forces when compared with continuous rotation. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Fracture resistance of dental nickel-titanium rotary instruments with novel surface treatment: Thin film metallic glass coating.

Science.gov (United States)

Chi, Chih-Wen; Deng, Yu-Lun; Lee, Jyh-Wei; Lin, Chun-Pin

2017-05-01

Dental nickel-titanium (NiTi) rotary instruments are widely used in endodontic therapy because they are efficient with a higher success rate. However, an unpredictable fracture of instruments may happen due to the surface characteristics of imperfection (or irregularity). This study assessed whether a novel surface treatment could increase fatigue fracture resistance of dental NiTi rotary instruments. A 200- or 500-nm thick Ti-zirconium-boron (Ti-Zr-B) thin film metallic glass was deposited on ProTaper Universal F2 files using a physical vapor deposition process. The characteristics of coating were analyzed by scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. In cyclic fatigue tests, the files were performed in a simulated root canal (radius=5 mm, angulation=60°) under a rotating speed of 300rpm. The fatigue fractured cross sections of the files were analyzed with their fractographic performances through scanning electron microscopy images. The amorphous structure of the Ti-Zr-B coating was confirmed by transmission electron microscopy and X-ray diffractometry. The surface of treated files presented smooth morphologies without grinding irregularity. For the 200- and 500-nm surface treatment groups, the coated files exhibited higher resistance of cyclic fatigue than untreated files. In fractographic analysis, treated files showed significantly larger crack-initiation zone; however, no significant differences in the areas of fatigue propagation and catastrophic fracture were found compared to untreated files. The novel surface treatment of Ti-Zr-B thin film metallic glass on dental NiTi rotary files can effectively improve the fatigue fracture resistance by offering a smooth coated surface with amorphous microstructure. Copyright © 2016. Published by Elsevier B.V.

The effect of educational intervention on the adoption of nickel-titanium rotary instrumentation in a Public Dental Service.

Science.gov (United States)

Reit, C; Bergenholtz, G; Caplan, D; Molander, A

2007-04-01

To study the influence of two educational programmes on the adoption of nickel-titanium rotary instrumentation (NTRI) amongst general dental practitioners in a short-term as well as a long-term perspective. All dentists employed in the Gothenburg Dental service (n = 148) were enrolled in the study. The clinics in the organization were randomly assigned to one of two educational programmes. In the first programme a 4-h lecture on root canal instrumentation was given. In the second programme the lecture course was supplemented by a 6-h hands-on training session. The short-term effect was measured by a questionnaire distributed 6 months after completed education. The long-term effect was evaluated 4 years later. The overall utilization rate of NTRI increased from 4% to 73%. However, lectures in combination with hands-on training resulted in a better short-term acceptance rate (94%) than if teaching was given only in lecture-format (53%) (P = 0.000). As a consequence, all staff were offered hands-on training. The long-term adoption rate was 88%. Reasons for accepting the new technology usually were found within the 'relative advantage' category. Common reasons for dentists not to adopt NTRI were that they could not get started or that they found no advantage over the old technology. The short-term adoption of a new technology might be influenced by the design of an introductory educational programme. For clinical procedures, such as root canal instrumentation, the inclusion of hands-on training sessions seems to be important to reach a high acceptance rate.

[The influence of autoclave sterilization on surface characteristics and cyclic fatigue resistance of 3 nickel-titanium rotary instruments].

Science.gov (United States)

Li, Xiang-fen; Zheng, Ping; Xu, Li; Su, Qin

2015-12-01

To investigate the effects of autoclave sterilization on surface characteristics and cyclic fatigue resistance of 3 types of nickel-titanium rotary instruments (K3, Mtwo, ProTaper). Three brands of NiTi rotary endodontic instruments of the same size (tip diameter 0.25 mm and constant 0.06 taper) were selected: K3, Mtwo and Protaper (F2). 24 instruments for each brand were used to evaluate the effects of autoclave sterilization on inner character in the as-received condition and after subjection to 0, 1, 5, and 10 sterilization cycles (6 for each group). Time to fracture (TtF) from the start of the test to the moment of file breakage and the length of the fractured fragment were recorded. Means and standard deviations of TtF and fragment length were calculated. The data was analyzed with SPSS13.0 software package. Another 12 NiTi rotary instruments for each brand were used, 6 subjected to 10 autoclave sterilization cycles and the other as control. Scanning electron microscope was used to observe the changes in surface topography and inner character. For cyclic fatigue resistance, when sterilization was not performed, K3 showed the highest value of TtF means and ProTaper the lowest. The differences between each brand were statistically significant (Pinstruments were intensified greatly after 10 cycles of sterilization. Cycle fatigue resistance is different among instruments of different brands. Autoclave sterilization may increase fatigue resistance of the 3 brands. Autoclave sterilization may increase the surface roughness and inner defects in cross section.

The effects of cold rolling and the subsequent heat treatments on the shape memory and the superelasticity characteristics of Cu73Al16Mn11 shape memory alloy

Science.gov (United States)

Babacan, N.; Ma, J.; Turkbas, O. S.; Karaman, I.; Kockar, B.

2018-01-01

In the present study, the effect of thermo-mechanical treatments on the shape memory and the superelastic characteristics of Cu73Al16Mn11 (at%) shape memory alloy were investigated. 10%, 50% and 70% cold rolling and subsequent heat treatment processes were conducted to achieve strengthening via grain size refinement. 70% grain size reduction compared to the homogenized condition was obtained using 70% cold rolling and subsequent recrystallization heat treatment technique. Moreover, 10% cold rolling was applied to homogenized specimen to reveal the influence of the low percentage cold rolling reduction with no heat treatment on shape memory properties of Cu73Al16Mn11 (at%) alloy. Stress free transformation temperatures, monotonic tension and superelasticity behaviors of these samples were compared with those of the as-aged sample. Isobaric heating-cooling experiments were also conducted to see the dimensional stability of the samples as a function of applied stress. The 70% grain-refined sample exhibited better dimensional stability showing reduced residual strain levels upon thermal cycling under constant stress compared with the as-aged material. However, no improvement was achieved with grain size reduction in the superelasticity experiments. This distinctive observation was attributed to the difference in the magnitude of the stress levels achieved during two different types of experiments which were the isobaric heating-cooling and superelasticity tests. Intergranular fracture due to the stress concentration overcame the strengthening effect via grain refinement in the superelasticity tests at higher stress values. On the other hand, the strength of the material and resistance of material against plastic deformation upon phase transformation were increased as a result of the grain refinement at lower stress values in the isobaric heating-cooling experiments.

Mechanical properties of NiTi and CuNiTi wires used in orthodontic treatment. Part 2: Microscopic surface appraisal and metallurgical characteristics

Directory of Open Access Journals (Sweden)

Marco Abdo Gravina

2014-01-01

Full Text Available OBJECTIVE: This research aimed at comparing the qualitative chemical compositions and the surface morphology of fracture regions of eight types of Nickel (Ni Titanium (Ti conventional wires, superelastic and heat-activated (GAC, TP, Ormco, Masel, Morelli and Unitek, to the wires with addition of copper (CuNiTi 27oC and 35oC, Ormco after traction test. METHODS: The analyses were performed in a scanning electronic microscope (JEOL, model JSM-5800 LV with EDS system of microanalysis (energy dispersive spectroscopy. RESULTS : The results showed that NiTi wires presented Ni and Ti as the main elements of the alloy with minimum differences in their composition. The CuNiTi wires, however, presented Ni and Ti with a significant percentage of copper (Cu. As for surface morphology, the wires that presented the lowest wire-surface roughness were the superelastic ones by Masel and Morelli, while those that presented the greatest wire-surface roughness were the CuNiTi 27oC and 35oC ones by Ormco, due to presence of microcavity formed as a result of pulling out some particles, possibly of NiTi. 4 The fracture surfaces presented characteristics of ductile fracture, with presence of microcavities. The superelastic wires by GAC and the CuNiTi 27oC and the heat-activated ones by Unitek presented the smallest microcavities and the lowest wire-surface roughness with regard to fracture, while the CuNiTi 35oC wires presented inadequate wire-surface roughness in the fracture region. CONCLUSION: CuNiTi 35oC wires did not present better morphologic characteristics in comparison to the other wires with regard to surfaces and fracture region.

A comparison of roughness parameters and friction coefficients of aesthetic archwires.

Science.gov (United States)

Rudge, Philippa; Sherriff, Martyn; Bister, Dirk

2015-02-01

Compare surface roughness of 'aesthetic' nickel-titanium (NiTi) archwires with their dynamic frictional properties. Archwires investigated were: four fully coated tooth coloured [Forestadent: Biocosmetic (FB) and Titanol Cosmetic (FT); TOC Tooth Tone (TT); and Hawley Russell Coated Superelastic NiTi (HRC)]; two partially coated tooth coloured [DB Euroline Microcoated (DB) and TP Aesthetic NiTi (TP)]; two rhodium coated [TOC Sentalloy (TS) and Hawley Russell Rhodium Coated Superelastic NiTi (HRR)]; and two controls: stainless steel [Forestadent Steel (FS)] and NiTi archwire [Forestadent Titanol Superelastic (FN)]. Surface roughness [profilometry (Rugosurf)] was compared with frictional coefficients for archwire/bracket/ligature combinations (n = 10). Analysis of variance, Sidak's multiple comparison of means, and Spearman's correlation coefficient were used for analysis. Roughness coefficients were from low to high: FB; FN; TT; FS; TS; HRR; FT; DB; TP; HRC. Friction coefficients were from low to high: TP; FS; FN; HRR; FT; DB; FB; HRC; TS; TT. Coated archwires generally exhibited higher friction than uncoated controls. TP had the lowest friction but this was not statistically significant (P < 0.05). Friction of tooth coloured coated archwires were significantly different for some wires. Spearman's correlation did not demonstrate consistency between surface roughness (R a) and dynamic friction. Aesthetic archwires investigated had either low surface roughness or low frictional resistance but not both properties simultaneously. Causes for friction are likely to be multifactorial and do not appear to be solely determined by surface roughness (measured by profilometry). For selecting the most appropriate aligning archwire, both surface roughness and frictional resistance need to be considered. © The Author 2014. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Opportunities in the electrowinning of molten titanium from titanium dioxide

CSIR Research Space (South Africa)

Van Vuuren, DS

2005-10-01

Full Text Available used, the following forms of titanium are produced: titanium sponge, sintered electrode sponge, powder, molten titanium, electroplated titanium, hydride powder, and vapor-phase depos- ited titanium. Comparing the economics of alter- native...-up for producing titanium via the Kroll process is approximately as follows: ilmenite ($0.27/kg titanium sponge); titanium slag ($0.75/kg titanium sponge); TiCl4 ($3.09/kg titanium sponge); titanium sponge raw materials costs ($5.50/kg titanium sponge); total...

Intracluster superelastic scattering via sequential photodissociation in small HI clusters

International Nuclear Information System (INIS)

Chastaing, D.; Underwood, J.; Wittig, C.

2003-01-01

The photodissociation of expansion-cooled HI monomer by using 266 nm radiation yields H atoms having 12 830 and 5287 cm-1 of translational energy in the HI center-of-mass system for the I( 2 P 3/2 ) and I( 2 P 1/2 ) (i.e., I and I * , respectively) co-fragments. Irradiating HI clusters [i.e., (HI) n , with n=2 being the dominant cluster] with 266 nm radiation produces, among other things, some H atoms whose translational energies are peaked at 20 285 cm-1, which is 7455 cm-1 higher in energy than the more energetic of the monomer peaks. These very fast H atoms arise from sequential photodissociation within the clusters. Namely, a weakly bound I*·(HI) n-1 complex is first created by the photodissociation of an HI moiety within (HI) n , and then the photodissociation of a second HI moiety [within I*·(HI) n-1 ] produces a fast H atom that scatters from the nearby I*, in some cases deactivating it in the process. Thus, the latter superelastically scattered H atom acquires, as translational energy, nearly all of the I* energy (7603 cm-1). For example, for the dimer, the first dissociation event, (HI) 2 +hv→H+I(I*)·HI, is followed by I*·HI+hv→H superelastic +I-I. High quality potentials for the relevant HI excited states have been calculated recently, and coupling between 3 Π 0 + (which correlates with I * ) and 1 Π (which correlates with I) has been shown to be due to spin-rotation interaction. There is a high degree of separability between the photodissociation of the second HI moiety and the subsequent H+I * scattering (within a given cluster). This is due mainly to the shape of the 3 Π 0 + potential; specifically, it has a shallow well that persists to small r. The shape of the 3 Π 0 + potential is influenced by relativity; i.e., strong spin-orbit coupling maintains the I* spherical electron density to relatively small r. The 3 Π 0 + → 1 Π transition probabilities are calculated for H+I * collisions having different values of the collisional orbital

Surface preparation process of a uranium titanium alloy, in particular for chemical nickel plating

International Nuclear Information System (INIS)

Henri, A.; Lefevre, D.; Massicot, P.

1987-01-01

In this process the uranium alloy surface is attacked with a solution of lithium chloride and hydrochloric acid. Dissolved uranium can be recovered from the solution by an ion exchange resin. Treated alloy can be nickel plated by a chemical process [fr

Improvement on corrosion resistance of NiTi orthopedic materials by carbon plasma immersion ion implantation

International Nuclear Information System (INIS)

Poon, Ray W.Y.; Ho, Joan P.Y.; Luk, Camille M.Y.; Liu Xuanyong; Chung, Jonathan C.Y.; Chu, Paul K.; Yeung, Kelvin W.K.; Lu, William W.; Cheung, Kenneth M.C.

2006-01-01

Nickel-titanium shape memory alloys (NiTi) have potential applications as orthopedic implants because of their unique super-elastic properties and shape memory effects. However, the problem of out-diffusion of harmful Ni ions from the alloys during prolonged use inside a human body must be overcome before they can be widely used in orthopedic implants. In this work, we enhance the corrosion resistance of NiTi using carbon plasma immersion ion implantation and deposition (PIII and D). Our corrosion and simulated body fluid tests indicate that either an ion-mixed amorphous carbon coating fabricated by PIII and D or direct carbon PIII can drastically improve the corrosion resistance and block the out-diffusion of Ni from the materials. Results of atomic force microscopy (AFM) indicate that both C 2 H 2 -PIII and D and C 2 H 2 -PIII do not roughen the original flat surface to an extent that can lead to degradation in corrosion resistance

Effect of Sn addition on the microstructure and superelasticity in Ti-Nb-Mo-Sn alloys.

Science.gov (United States)

Zhang, D C; Yang, S; Wei, M; Mao, Y F; Tan, C G; Lin, J G

2012-09-01

Ti-7.5Nb-4Mo-xSn (x=0-4at%) alloys were developed as the biomedical materials. The effect of the Sn content on the microstructure and superelasticity of the alloys was investigated. It is found that Sn is a strong stabilizer of the β phase, which is effective in suppressing the formation of α″ and ω phases in the alloys. Moreover, the Sn addition has a significant impact on the mechanical properties of the alloys. With the increase of Sn addition, the yield stress of the alloys increase, but their elastic modulus, the fracture strength and the ductility decrease, and the deformation mode of the alloys changes from (322) twining to α″ transformation and then to slip. The Ti-7.5Nb-4Mo-1Sn and Ti-7.5Nb-4Mo-3Sn alloys exhibit a good superelasticity with a high σ(SIM) due to the relatively high athermal ω phases containing or the solution hardening at room temperature. Under the maximum strain of 5%, Ti-7.5Nb-4Mo-3Sn (at%) alloy exhibits higher super elastic stability than that of Ti-7.5Nb-4Mo-1Sn alloy. Copyright © 2012 Elsevier Ltd. All rights reserved.

First interactions between hydrogen and stress-induced reverse transformation of Ni-Ti superelastic alloy

Science.gov (United States)

Yokoyama, Ken'ichi; Hashimoto, Tatsuki; Sakai, Jun'ichi

2017-11-01

The first dynamic interactions between hydrogen and the stress-induced reverse transformation have been investigated by performing an unloading test on a Ni-Ti superelastic alloy subjected to hydrogen charging under a constant applied strain in the elastic deformation region of the martensite phase. Upon unloading the specimen, charged with a small amount of hydrogen, no change in the behaviour of the stress-induced reverse transformation is observed in the stress-strain curve, although the behaviour of the stress-induced martensite transformation changes. With increasing amount of hydrogen charging, the critical stress for the reverse transformation markedly decreases. Eventually, for a larger amount of hydrogen charging, the reverse transformation does not occur, i.e. there is no recovery of the superelastic strain. The residual martensite phase on the side surface of the unloaded specimen is confirmed by X-ray diffraction. Upon training before the unloading test, the properties of the reverse transformation slightly recover after ageing in air at room temperature. The present study indicates that to change the behaviour of the reverse transformation a larger amount of hydrogen than that for the martensite transformation is necessary. In addition, it is likely that a substantial amount of hydrogen in solid solution more strongly suppresses the reverse transformation than hydrogen trapped at defects, thereby stabilising the martensite phase.

Rate-dependent response of superelastic Cu–Al–Mn alloy rods to tensile cyclic loads

International Nuclear Information System (INIS)

Araki, Yoshikazu; Maekawa, Nao; Omori, Toshihiro; Sutou, Yuji; Kainuma, Ryosuke; Ishida, Kiyohito

2012-01-01

We report the results of tensile cyclic loading tests conducted to examine the dependence of constitutive relations for superelastic Cu–Al–Mn alloy rods on loading rates. Recently, Cu–Al–Mn alloy rods with diameters up to 8 mm have been developed by the authors, and it has been demonstrated that these rods have excellent superelastic strains of more than 8%, which is comparable to Ni–Ti alloys and far superior to other Cu-based alloys. No information is available, however, on the rate dependence of constitutive relations for Cu–Al–Mn alloys. In this study, we prepare two Cu–Al–Mn alloy rod specimens, whose lengths and diameters are 150 mm and 8 mm, respectively. Their stress–strain relations are examined under the loading frequencies of 0.001, 0.5, and 1 Hz with constant strain amplitude of 4.5%. It was found from the tests that the maximum stress increase in Cu–Al–Mn alloys due to higher loading rate was less than 5%. Thermo-mechanical analysis predicts that stress increase in Cu–Al–Mn alloys is about 1/4 of that in Ni–Ti alloys, which agrees reasonably well with the experimental observations. Such low stress increase is highly desirable in the design of seismic devices such as dampers and isolators. (fast track communication)

Observation on the transformation domains of super-elastic NiTi shape memory alloy and their evolutions during cyclic loading

International Nuclear Information System (INIS)

Xie, Xi; Kan, Qianhua; Kang, Guozheng; Li, Jian; Qiu, Bo; Yu, Chao

2016-01-01

The strain field of a super-elastic NiTi shape memory alloy (SMA) and its variation during uniaxial cyclic tension-unloading were observed by a non-contact digital image correlation method, and then the transformation domains and their evolutions were indirectly investigated and discussed. It is seen that the super-elastic NiTi (SMA) exhibits a remarkable localized deformation and the transformation domains evolve periodically with the repeated cyclic tension-unloading within the first several cycles. However, the evolutions of transformation domains at the stage of stable cyclic transformation depend on applied peak stress: when the peak stress is low, no obvious transformation band is observed and the strain field is nearly uniform; when the peak stress is large enough, obvious transformation bands occur due to the residual martensite caused by the prevention of enriched dislocations to the reverse transformation from induced martensite to austenite. Temperature variations measured by an infrared thermal imaging method further verifies the formation and evolution of transformation domains. (paper)

Observation on the transformation domains of super-elastic NiTi shape memory alloy and their evolutions during cyclic loading

Science.gov (United States)

Xie, Xi; Kan, Qianhua; Kang, Guozheng; Li, Jian; Qiu, Bo; Yu, Chao

2016-04-01

The strain field of a super-elastic NiTi shape memory alloy (SMA) and its variation during uniaxial cyclic tension-unloading were observed by a non-contact digital image correlation method, and then the transformation domains and their evolutions were indirectly investigated and discussed. It is seen that the super-elastic NiTi (SMA) exhibits a remarkable localized deformation and the transformation domains evolve periodically with the repeated cyclic tension-unloading within the first several cycles. However, the evolutions of transformation domains at the stage of stable cyclic transformation depend on applied peak stress: when the peak stress is low, no obvious transformation band is observed and the strain field is nearly uniform; when the peak stress is large enough, obvious transformation bands occur due to the residual martensite caused by the prevention of enriched dislocations to the reverse transformation from induced martensite to austenite. Temperature variations measured by an infrared thermal imaging method further verifies the formation and evolution of transformation domains.

Self-repairing performance of concrete beams strengthened using superelastic SMA wires in combination with adhesives released from hollow fibers

International Nuclear Information System (INIS)

Kuang Yachuan; Ou Jinping

2008-01-01

By taking advantage of the superelastic effect of shape memory alloy (SMA) and the cohering characteristic of repairing adhesive, a smart self-repairing concrete beam with damage self-repairing performance has been developed. In order to verify the potential self-repairing capacity of smart concrete beams reinforced with SMA wires and brittle fibers containing adhesives, static loading tests were conducted. Experimental results show that the superelastic SMA wires added self-restoration capacity to concrete beams, the deflection of the beams reversed and the crack closed almost completely after unloading. After the release of adhesive from the broken-open fibers into the cracks from the first loading, stress was redistributed to the uncracked section where a new crack was formed, while the sealed crack remained closed during reloading for the smart concrete beams reinforced with SMA wires and brittle fibers containing adhesives. While the original cracks experienced reopening, the load was carried directly by the wires during reloading for concrete beams reinforced with SMA wires

Nickel in nails, hair and plasma from nickel-hypersensitive women

DEFF Research Database (Denmark)

Gammelgaard, Bente; Veien, Niels

1990-01-01

The concentrations of nickel in finger-nails, toe-nails, hair and plasma from 71 nickel-hypersensitive women and 20 non-hypersensitive women were determined. Nickel concentrations in finger-nails were significantly higher than in toe-nails in both the nickel-hypersensitive group and the control...... group. Nickel-sensitive women had significantly higher levels of nickel in toe-nails, hair and plasma than had control subjects, whereas there was no significant difference in nickel concentration in finger-nails between the two groups. No correlation could be demonstrated between nickel levels in any...... combination of nails, hair and plasma in the nickel-hypersensitive or in the control group....

Cell Attachment Following Instrumentation with Titanium and Plastic Instruments, Diode Laser, and Titanium Brush on Titanium, Titanium-Zirconium, and Zirconia Surfaces.

Science.gov (United States)

Lang, Melissa S; Cerutis, D Roselyn; Miyamoto, Takanari; Nunn, Martha E

2016-01-01

The aim of this study was to evaluate the surface characteristics and gingival fibroblast adhesion of disks composed of implant and abutment materials following brief and repeated instrumentation with instruments commonly used in procedures for implant maintenance, stage-two implant surgery, and periimplantitis treatment. One hundred twenty disks (40 titanium, 40 titaniumzirconium, 40 zirconia) were grouped into treatment categories of instrumentation by plastic curette, titanium curette, diode microlaser, rotary titanium brush, and no treatment. Twenty strokes were applied to half of the disks in the plastic and titanium curette treatment categories, while half of the disks received 100 strokes each to simulate implant maintenance occurring on a repetitive basis. Following analysis of the disks by optical laser profilometry, disks were cultured with human gingival fibroblasts. Cell counts were conducted from scanning electron microscopy (SEM) images. Differences in surface roughness across all instruments tested for zirconia disks were negligible, while both titanium disks and titaniumzirconium disks showed large differences in surface roughness across the spectrum of instruments tested. The rotary titanium brush and the titanium curette yielded the greatest overall mean surface roughness, while the plastic curette yielded the lowest mean surface roughness. The greatest mean cell counts for each disk type were as follows: titanium disks with plastic curettes, titanium-zirconium disks with titanium curettes, and zirconia disks with the diode microlaser. Repeated instrumentation did not result in cumulative changes in surface roughness of implant materials made of titanium, titanium-zirconium, or zirconia. Instrumentation with plastic implant curettes on titanium and zirconia surfaces appeared to be more favorable than titanium implant curettes in terms of gingival fibroblast attachment on these surfaces.

Forces released during alignment with a preadjusted appliances with SPEED supercable wire and different types of elastomeric ligatures

Directory of Open Access Journals (Sweden)

Suruchi Jatol-Tekade

2016-01-01

Full Text Available Introduction: The purpose of this in vitro study was to evaluate a new combination of wire and ligature to reduce friction further by combining slide ligatures and supercable wires. Materials and Methods: The testing model consisted of five stainless steel 0.022 inch preadjusted brackets for second premolar, first premolar, canine, lateral incisor, and central incisor. The canine bracket was welded to a sliding bar that allowed different vertical positions. The forces generated by five sizes of wires superelastic nickel-titanium (SE Ni-Ti (Unitek Nitinol Super-Elastic Archwire of diameter 0.012", 0.014", 0.016", 0.018", and 0.020" inch and three sizes of SPEED supercable wires (0.016", 0.018", and 0.022" inch with the two types of elastomeric ligatures; conventional elastomeric ligatures (CELs (Unitek, silver mini modules, with inside diameter of 1.3 mm and thickness of 0.9 mm and nonconventional elastomeric ligatures (NCELs (Slide, Leone Orthodontic Products, Sesto Fiorentino, Firenze, Italy at different amounts of upward canine misalignment (CM (1.5, 3, 4.5, and 6 mm were recorded. Results and Conclusions: Significant differences between CEL and NCEL were found for all tested variables (P - 0.01 a noticeable amount of force was generated with the NCEL at all four canine positions with all three wire sizes (from about 50 to about 150 g. With 4.5 mm of CM or more, the average amount of released force with the CEL was approximately zero.

Corrosion investigation of multilayered ceramics and experimental nickel alloys in SCWO process environments

International Nuclear Information System (INIS)

Garcia, K.M.; Mizia, R.

1995-02-01

A corrosion investigation was done at MODAR, Inc., using a supercritical water oxidation (SCWO) vessel reactor. Several types of multilayered ceramic rings and experimental nickel alloy coupons were exposed to a chlorinated cutting oil TrimSol, in the SCWO process. A corrosion casing was designed and mounted in the vessel reactor with precautions to minimize chances of degrading the integrity of the pressure vessel. Fifteen of the ceramic coated rings were stacked vertically in the casing at one time for each test. There was a total of 36 rings. The rings were in groupings of three rings that formed five sections. Each section saw a different SCWO environment, ranging from 650 to 300 degrees C. The metal coupons were mounted on horizontal threaded holders welded to a vertical rod attached to the casing cover in order to hang down the middle of the casing. The experimental nickel alloys performed better than the baseline nickel alloys. A titania multilayered ceramic system sprayed onto a titanium ring remained intact after 120-180 hours of exposure. This is the longest time any coating system has withstood such an environment without significant loss

Corrosion investigation of multilayered ceramics and experimental nickel alloys in SCWO process environments

Energy Technology Data Exchange (ETDEWEB)

Garcia, K.M.; Mizia, R.

1995-02-01

A corrosion investigation was done at MODAR, Inc., using a supercritical water oxidation (SCWO) vessel reactor. Several types of multilayered ceramic rings and experimental nickel alloy coupons were exposed to a chlorinated cutting oil TrimSol, in the SCWO process. A corrosion casing was designed and mounted in the vessel reactor with precautions to minimize chances of degrading the integrity of the pressure vessel. Fifteen of the ceramic coated rings were stacked vertically in the casing at one time for each test. There was a total of 36 rings. The rings were in groupings of three rings that formed five sections. Each section saw a different SCWO environment, ranging from 650 to 300{degrees}C. The metal coupons were mounted on horizontal threaded holders welded to a vertical rod attached to the casing cover in order to hang down the middle of the casing. The experimental nickel alloys performed better than the baseline nickel alloys. A titania multilayered ceramic system sprayed onto a titanium ring remained intact after 120-180 hours of exposure. This is the longest time any coating system has withstood such an environment without significant loss.

Precipitation hardenable iron-nickel-chromium alloy having good swelling resistance and low neutron absorbence

International Nuclear Information System (INIS)

Korenko, M.K.; Merrick, H.F.; Gibson, R.C.

1982-01-01

An iron-nickel-chromium age-hardenable alloy suitable for use in fast breeder reactor ducts and cladding utilizes the gamma-double prime strengthening phase and has a morphology of the gamma-double prime phase enveloping the gamma-prime phase and delta phase distributed at or near the grain boundaries. The alloy consists essentially of about 40-50 percent nickel, 7.5-14 percent chromium, 1.5-4 percent niobium, .25-.75 percent silicon, 1-3 percent titanium, .1-.5 percent aluminum, .02-1 percent carbon, .002-.015 percent boron, and the balance iron. Up to 2 percent manganese and up to .01 percent magnesium may be added to inhibit trace element effects; up to .1 percent zirconium may be added to increase radiation swelling resistance; and up to 3 percent molybdenum may be added to increase strength

Thermal and Irradiation Creep Behavior of a Titanium Aluminide in Advanced Nuclear Plant Environments

Science.gov (United States)

Magnusson, Per; Chen, Jiachao; Hoffelner, Wolfgang

2009-12-01

Titanium aluminides are well-accepted elevated temperature materials. In conventional applications, their poor oxidation resistance limits the maximum operating temperature. Advanced reactors operate in nonoxidizing environments. This could enlarge the applicability of these materials to higher temperatures. The behavior of a cast gamma-alpha-2 TiAl was investigated under thermal and irradiation conditions. Irradiation creep was studied in beam using helium implantation. Dog-bone samples of dimensions 10 × 2 × 0.2 mm3 were investigated in a temperature range of 300 °C to 500 °C under irradiation, and significant creep strains were detected. At temperatures above 500 °C, thermal creep becomes the predominant mechanism. Thermal creep was investigated at temperatures up to 900 °C without irradiation with samples of the same geometry. The results are compared with other materials considered for advanced fission applications. These are a ferritic oxide-dispersion-strengthened material (PM2000) and the nickel-base superalloy IN617. A better thermal creep behavior than IN617 was found in the entire temperature range. Up to 900 °C, the expected 104 hour stress rupture properties exceeded even those of the ODS alloy. The irradiation creep performance of the titanium aluminide was comparable with the ODS steels. For IN617, no irradiation creep experiments were performed due to the expected low irradiation resistance (swelling, helium embrittlement) of nickel-base alloys.

Young´s modulus of austenite and martensite phases in superelastic NiTi wires

Czech Academy of Sciences Publication Activity Database

Šittner, Petr; Heller, Luděk; Pilch, Jan; Curfs, C.; Alonso, T.; Favier, D.

2014-01-01

Roč. 23, č. 7 (2014), s. 2303-2314 ISSN 1059-9495. [International Conference on Shape Memory and Superelastic Technologies (SMST 2013). Praha, 21.05.2013-24.05.2013] R&D Projects: GA ČR GPP108/12/P111; GA ČR GAP107/12/0800; GA ČR GB14-36566G; GA ČR GA14-15264S Institutional support: RVO:68378271 Keywords : mechanical * modeling and simulation * non-ferrous metals Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.998, year: 2014

Finite element analysis of smart reinforced concrete beam with super elastic shape memory alloy subjected to static loading for seismic mitigation

Science.gov (United States)

Hamid, Nubailah Abd; Ismail, Muhammad Hussain; Ibrahim, Azmi; Adnan, Azlan

2018-05-01

Reinforced concrete beam has been among major applications in construction nowadays. However, the application of nickel titanium alloy as a replacement for steel rebar in reinforced concrete beam is a new approach nowadays despite of their ability to undergo large deformations and return to their undeformed shape by removal of stresses. In this paper, the response of simply supported reinforced concrete (RC) beams with smart rebars, control beam subjected to static load has been numerically studied, and highlighted, using finite element method (FEM) where the material employed in this study is the superelastic shape memory alloys (SESMA). The SESMA is a unique alloy that has the ability to undergo large deformations and return to their undeformed shape by removal of stresses. The size of the analysed beam is 125 mm × 270 mm × 2800 mm with 2 numbers of 12 mm diameter bars as main reinforcement for compression and 12 numbers of 12 as tension or hanger bars while 6 mm diameter at 100 mm c/c used as shear reinforcement bars respectively. The concrete was modelled using solid 65 element (in ANSYS) and rebars were modelled using beam 188 elements (in ANSYS). The result for reinforced concrete with nickel titanium alloy rebar is compared with the result obtained for reinforced concrete beam with steel rebar in term of flexural behavior, load displacement relationship, crack behaviour and failure modes for various loading conditions starting from 10kN to 100kN using 3D FE modelling in ANSYS v 15. The response and result obtained from the 3D finite element analysis used in this study is load-displacement curves, residual displacements, Von-Misses, strain and stiffness are suitable for the corresponding result showed a satisfactory performance in the structural analysis. Resultant displacement, Von-Mises stress and maximum strain were influenced by the factors of the material properties, load increments and the mesh size. Nickel titanium alloy was superior to the

Nickel-induced cytokine production from mononuclear cells in nickel-sensitive individuals and controls. Cytokine profiles in nickel-sensitive individuals with nickel allergy-related hand eczema before and after nickel challenge

DEFF Research Database (Denmark)

Borg, L; Christensen, J M; Kristiansen, J

2000-01-01

Exposure to nickel is a major cause of allergic contact dermatitis which is considered to be an inflammatory response induced by antigen-specific T cells. Here we describe the in vitro analysis of the nickel-specific T-cell-derived cytokine response of peripheral blood mononuclear cells from 35...... was somewhat of a surprise, since previous studies have suggested a Th1 response in nickel-mediated allergic contact dermatitis. Subsequently, the nickel-allergic individuals were randomized to experimental exposure to nickel or vehicle in a double-blind design. A daily 10-min exposure of one finger to 10 ppm...... nickel solution for 1 week followed by 100 ppm for an additional week evoked a clinical response of hand eczema in the nickel-exposed group. Blood samples were drawn on days 7 and 14 after the start of this exposure to occupationally relevant concentrations of nickel. No statistically significant...

Deflection and Flexural Strength Effects on the Roughness of Aesthetic-Coated Orthodontic Wires.

Science.gov (United States)

Albuquerque, Cibele Gonçalves de; Correr, Américo Bortolazzo; Venezian, Giovana Cherubini; Santamaria, Milton; Tubel, Carlos Alberto; Vedovello, Silvia Amélia Scudeler

2017-01-01

The aim was to evaluate the flexural strength and the effects of deflection on the surface roughness of esthetic orthodontic wires. The sample consisted of 70 archwire 0.014-inch: polytetrafluorethylene (PTFE)-coated Nickel-Titanium (Niti) archwires (Titanol Cosmetic-TC, Flexy Super Elastic Esthetic-FSE, esthetic Nickel Titanium Wire-ANT); epoxy resin-coated Niti archwires (Spectra-S, Niticosmetic-TEC); gold and rhodium coated Niti (Sentalloy-STC) and a control group (superelastic Niti (Nitinol-NS). The initial roughness was evaluated with a rugosimeter. After that, the wires were submitted to flexural test in an universal testing machine. Each wire was deflected up to 2 mm at a speed of 1 mm/min. After flexural test, the roughness of the wires was evaluted on the same surface as that used for the initial evaluation. The data of roughness and flexural strength were analyzed by one-way ANOVA and Tukey's test (a=0.05). Student t-test compared roughness before and after deflection (a =0.05). The roughness of S and ANT (epoxy resin and PTFE-coated wires, respectively), before and after deflection, was significantly higher than the other groups (p<0.05). Wire deflection significantly increased the roughness of the wires S and STC (p<0.05). The flexural strength of groups FSE and NS (PTFE and uncoated) was higher compared with that of the other groups (p<0.05). We concluded that the roughness and flexural strength of the orthodontic wires does not depend on the type of the esthetic coating, but it is influenced by the method of application of this coating. The deflection can increase the roughness of the esthetic orthodontic wires.

Superelastic SMA–FRP composite reinforcement for concrete structures

International Nuclear Information System (INIS)

Wierschem, Nicholas; Andrawes, Bassem

2010-01-01

For many years there has been interest in using fiber-reinforced polymers (FRPs) as reinforcement in concrete structures. Unfortunately, due to their linear elastic behavior, FRP reinforcing bars are never considered for structural damping or dynamic applications. With the aim of improving the ductility and damping capability of concrete structures reinforced with FRP reinforcement, this paper studies the application of SMA–FRP, a relatively novel type of composite reinforced with superelastic shape memory alloy (SMA) wires. The cyclic tensile behavior of SMA–FRP composites are studied experimentally and analytically. Tests of SMA–FRP composite coupons are conducted to determine their constitutive behavior. The experimental results are used to develop and calibrate a uniaxial SMA–FRP analytical model. Parametric and case studies are performed to determine the efficacy of the SMA–FRP reinforcement in concrete structures and the key factors governing its behavior. The results show significant potential for SMA–FRP reinforcement to improve the ductility and damping of concrete structures while still maintaining its elastic characteristic, typical of FRP reinforcement

Effectiveness of nickel-titanium springs vs elastomeric chains in orthodontic space closure: A systematic review and meta-analysis.

Science.gov (United States)

Mohammed, H; Rizk, M Z; Wafaie, K; Almuzian, M

2018-02-01

The aim of this study is to explore the effectiveness of nickel titanium closing springs (NiTi-CS) and elastomeric power chains (EPC) in orthodontic space closure and to assess the adverse periodontal effects, cost efficiency and patient-centred outcomes between both of these methods. An electronic search of online databases (Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Scopus, LILACS and Web of Science), reference lists and grey literature as well as hand search were conducted without language restriction up to November/2017. Two authors blindly and in duplicate were involved in study selection, quality assessment and the extraction of data. Only randomized clinical trials (RCTs) were included. The quality of the studies was assessed using the Cochrane Collaboration's risk of bias tool. 95% confidence intervals and mean difference for continuous data were calculated. A meta-analysis that generated a random-effect model for the comparable outcomes was conducted, and heterogeneity was measured using I 2 statistic. Of 187 records, 4 RCTs met the criteria and were included in the quantitative synthesis featuring 290 test quadrants. Faster space closure with NiTi-CS was observed with a mean difference of (0.20 mm/month, 95% CI: 0.12 to 0.28). Loss of anchorage appears to be similar within both groups when synthesized qualitatively. With exception to anchorage loss, secondary outcomes could not be investigated in the included trials. There is a moderate quality of evidence suggesting a faster orthodontic space closure with the NiTi-CS when compared to EPC. A comparable amount of anchorage loss was observed regardless of the utilized method of space closure. Further high-quality RCTs with parallel-groups, reporting on the adverse effects and patient-centred values, are recommended. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Superelastic SMA U-shaped dampers with self-centering functions

Science.gov (United States)

Wang, Bin; Zhu, Songye

2018-05-01

As high-performance metallic materials, shape memory alloys (SMAs) have been investigated increasingly by the earthquake engineering community in recent years, because of their remarkable self-centering (SC) and energy-dissipating capabilities. This paper systematically presents an experimental study on a novel superelastic SMA U-shaped damper (SMA-UD) with SC function under cyclic loading. The mechanical properties, including strength, SC ability, and energy-dissipating capability with varying loading amplitudes and strain rates are evaluated. Test results show that excellent and stable flag-shaped hysteresis loops are exhibited in multiple loading cycles. Strain rate has a negligible effect on the cyclic behavior of the SMA-UD within the dynamic frequency range of typical interest in earthquake engineering. Furthermore, a numerical investigation is performed to understand the mechanical behavior of the SMA-UD. The numerical model is calibrated against the experimental results with reasonable accuracy. Then, the stress–strain states with different phase transformations are also discussed.

Ex vivo study on root canal instrumentation of two rotary nickel-titanium systems in comparison to stainless steel hand instruments.

Science.gov (United States)

Vaudt, J; Bitter, K; Neumann, K; Kielbassa, A M

2009-01-01

To investigate instrumentation time, working safety and the shaping ability of two rotary nickel-titanium (NiTi) systems (Alpha System and ProTaper Universal) in comparison to stainless steel hand instruments. A total of 45 mesial root canals of extracted human mandibular molars were selected. On the basis of the degree of curvature the matched teeth were allocated randomly into three groups of 15 teeth each. In group 1 root canals were prepared to size 30 using a standardized manual preparation technique; in group 2 and 3 rotary NiTi instruments were used following the manufacturers' instructions. Instrumentation time and procedural errors were recorded. With the aid of pre- and postoperative radiographs, apical straightening of the canal curvature was determined. Photographs of the coronal, middle and apical cross-sections of the pre- and postoperative canals were taken, and superimposed using a standard software. Based on these composite images the portion of uninstrumented canal walls was evaluated. Active instrumentation time of the Alpha System was significantly reduced compared with ProTaper Universal and hand instrumentation (P < 0.05; anova). No instrument fractures occurred in any of the groups. The Alpha System revealed significantly less apical straightening compared with the other instruments (P < 0.05; Mann-Whitney U test). In the apical cross-sections Alpha System resulted in significantly less uninstrumented canal walls compared with stainless steel files (P < 0.05; chi-squared test). Despite the demonstrated differences between the systems, an apical straightening effect could not be prevented; areas of uninstrumented root canal wall were left in all regions using the various systems.

Effect of nickel oxide seed layers on annealed-amorphous titanium oxide thin films prepared using plasma-enhanced chemical vapor deposition

International Nuclear Information System (INIS)

Wu, Cheng-Yang; Hong, Shao-Chyang; Hwang, Fu-Tsai; Lai, Li-Wen; Lin, Tan-Wei; Liu, Day-Shan

2011-01-01

The effect of a nickel oxide (NiO x ) seed layer on the crystallization and photocatalytic activity of the sequentially plasma-enhanced chemical vapor deposited amorphous titanium oxide (TiO x ) thin film processed by a post-annealing process was investigated. The evolution of the crystalline structures, chemical bond configurations, and surface/cross-sectional morphologies of the annealed TiO x films, with and without a NiO x seed layer, was examined using X-ray diffractometer, Fourier transform infrared spectrometry, X-ray photoelectron spectroscopy, atomic force microscopy, and field emission scanning electron microscope measurements. Thermo- and photo-induced hydrophilicity was determined by measuring the contact angle of water droplet. Photocatalytic activity after UV light irradiation was evaluated from the decolorization of a methylene blue solution. The crystallization temperature of the TiO x film, deposited on a NiO x seed layer, was found to be lower than that of a pure TiO x film, further improving the thermo- and photo-induced surface super-hydrophilicity. The TiO x film deposited onto the NiO x seed layer, resulting in significant cluster boundaries, showed a rough surface morphology and proved to alleviate the anatase crystal growth by increasing the post-annealing temperature, which yielded a more active surface area and prohibited the recombination of photogenerated electrons and holes. The photocatalytic activity of the NiO x /TiO x system with such a textured surface therefore was enhanced and optimized through an adequate post-annealing process.

Effect of nickel oxide seed layers on annealed-amorphous titanium oxide thin films prepared using plasma-enhanced chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Wu, Cheng-Yang; Hong, Shao-Chyang [Institute of Electro-Optical and Materials Science, National Formosa University, Huwei, Yunlin, 63201, Taiwan (China); Hwang, Fu-Tsai [Department of Electro-Optical Engineering, National United University, Miao-Li, 36003, Taiwan (China); Lai, Li-Wen [ITRI South, Industrial Technology Research Institute, Liujia, Tainan, 73445, Taiwan (China); Lin, Tan-Wei [Institute of Electro-Optical and Materials Science, National Formosa University, Huwei, Yunlin, 63201, Taiwan (China); Liu, Day-Shan, E-mail: dsliu@sunws.nfu.edu.tw [Institute of Electro-Optical and Materials Science, National Formosa University, Huwei, Yunlin, 63201, Taiwan (China)

2011-10-31

The effect of a nickel oxide (NiO{sub x}) seed layer on the crystallization and photocatalytic activity of the sequentially plasma-enhanced chemical vapor deposited amorphous titanium oxide (TiO{sub x}) thin film processed by a post-annealing process was investigated. The evolution of the crystalline structures, chemical bond configurations, and surface/cross-sectional morphologies of the annealed TiO{sub x} films, with and without a NiO{sub x} seed layer, was examined using X-ray diffractometer, Fourier transform infrared spectrometry, X-ray photoelectron spectroscopy, atomic force microscopy, and field emission scanning electron microscope measurements. Thermo- and photo-induced hydrophilicity was determined by measuring the contact angle of water droplet. Photocatalytic activity after UV light irradiation was evaluated from the decolorization of a methylene blue solution. The crystallization temperature of the TiO{sub x} film, deposited on a NiO{sub x} seed layer, was found to be lower than that of a pure TiO{sub x} film, further improving the thermo- and photo-induced surface super-hydrophilicity. The TiO{sub x} film deposited onto the NiO{sub x} seed layer, resulting in significant cluster boundaries, showed a rough surface morphology and proved to alleviate the anatase crystal growth by increasing the post-annealing temperature, which yielded a more active surface area and prohibited the recombination of photogenerated electrons and holes. The photocatalytic activity of the NiO{sub x}/TiO{sub x} system with such a textured surface therefore was enhanced and optimized through an adequate post-annealing process.

Titanium ; dream new material

International Nuclear Information System (INIS)

Lee, Yong Tae; Kim Seung Eon; Heoon, Yong Taek; Jung, Hui Won

2001-11-01

The contents of this book are history of Titanium, present situation of Titanium industry, property of Titanium alloy, types of it, development of new alloy of Titanium smelting of Titanium, cast of Titanium and heat treatment of Titanium, Titanium alloy for plane, car parts, biological health care, and sport leisure and daily life, prospect, and Titanium industrial development of Titanium in China.

Removing nickel from nickel-coated carbon fibers

Science.gov (United States)

Hardianto, A.; Hertleer, C.; De Mey, G.; Van Langenhove, L.

2017-10-01

Conductive fibers/yarns are one of the most important materials for smart textiles because of their electrically conductive functionality combined with flexibility and light weight. They can be applied in many fields such as the medical sector, electronics, sensors and even as thermoelectric generators. Temperature sensors, for example, can be made using the thermocouple or thermopile principle which usually uses two different metal wires that can produce a temperature-dependent voltage. However, if metal wires are inserted into a textile structure, they will decrease the flexibility properties of the textile product. Nickel-coated Carbon Fiber (NiCF), a conductive textile yarn, has a potential use as a textile-based thermopile if we can create an alternating region of carbon and nickel along the fiber which in turn it can be used for substituting the metallic thermopile. The idea was to remove nickel from NiCF in order to obtain a yarn that contains alternating zones of carbon and nickel. Due to no literature reporting on how to remove nickel from NiCF, in this paper we investigated some chemicals to remove nickel from NiCF.

Behavioral interventions to reduce nickel exposure in a nickel processing plant.

Science.gov (United States)

Rumchev, Krassi; Brown, Helen; Wheeler, Amanda; Pereira, Gavin; Spickett, Jeff

2017-10-01

Nickel is a widely-used material in many industries. Although there is enough evidence that occupational exposure to nickel may cause respiratory illnesses, allergies, and even cancer, it is not possible to stop the use of nickel in occupational settings. Nickel exposure, however, can be controlled and reduced significantly in workplaces. The main objective of this study was to assess if educational intervention of hygiene behavior could reduce nickel exposure among Indonesian nickel smelter workers. Participants were randomly assigned to three intervention groups (n = 99). Group one (n = 35) received only an educational booklet about nickel, related potential health effects and preventive measures, group two (n = 35) attended a presentation in addition to the booklet, and group three (n = 29) received personal feedback on their biomarker results in addition to the booklet and presentations. Pre- and post-intervention air sampling was conducted to measure concentrations of dust and nickel in air along with worker's blood and urine nickel concentrations. The study did not measure significant differences in particles and nickel concentrations in the air between pre- and post-interventions. However, we achieved significant reductions in the post intervention urine and blood nickel concentrations which can be attributed to changes in personal hygiene behavior. The median urinary nickel concentration in the pre-intervention period for group one was 52.3 µg/L, for group two 57.4 µg/L, and group three 43.2 µg/L which were significantly higher (pnickel with significantly (p nickel levels of 0.1 µg/L for all groups. The study showed that educational interventions can significantly reduce personal exposure levels to nickel among Indonesian nickel smelter workers.

The effect of martensite plasticity on the cyclic deformation of super-elastic NiTi shape memory alloy

International Nuclear Information System (INIS)

Song, Di; Kang, Guozheng; Kan, Qianhua; Yu, Chao; Zhang, Chuanzeng

2014-01-01

Based on stress-controlled cyclic tension–unloading experiments with different peak stresses, the effect of martensite plasticity on the cyclic deformation of super-elastic NiTi shape memory alloy micro-tubes is investigated and discussed. The experimental results show that the reverse transformation from the induced martensite phase to the austenite phase is gradually restricted by the plastic deformation of the induced martensite phase caused by an applied peak stress that is sufficiently high (higher than 900 MPa), and the extent of such restriction increases with further increasing the peak stress. The residual and peak strains of super-elastic NiTi shape memory alloy accumulate progressively, i.e., transformation ratchetting occurs during the cyclic tension–unloading with peak stresses from 600 to 900 MPa, and the transformation ratchetting strain increases with the increase of the peak stress. When the peak stress is higher than 900 MPa, the peak strain becomes almost unchanged, but the residual strain accumulates and the dissipation energy per cycle decreases very quickly with the increasing number of cycles due to the restricted reverse transformation by the martensite plasticity. Furthermore, a quantitative relationship between the applied stress and the stabilized residual strain is obtained to reasonably predict the evolution of the peak strain and the residual strain. (paper)

Investigation on the Cyclic Response of Superelastic Shape Memory Alloy (SMA Slit Damper Devices Simulated by Quasi-Static Finite Element (FE Analyses

Directory of Open Access Journals (Sweden)

Jong Wan Hu

2014-02-01

Full Text Available In this paper, the superelastic shape memory alloy (SMA slit damper system as an alternative design approach for steel structures is intended to be evaluated with respect to inelastic behavior simulated by refined finite element (FE analyses. Although the steel slit dampers conventionally used for aseismic design are able to dissipate a considerable amount of energy generated by the plastic yielding of the base materials, large permanent deformation may occur in the entire structure. After strong seismic events, extra damage repair costs are required to restore the original configuration and to replace defective devices with new ones. Innovative slit dampers fabricated by superelastic SMAs that automatically recover their initial conditions only by the removal of stresses without heat treatment are introduced with a view toward mitigating the problem of permanent deformation. The cyclically tested FE models are calibrated to experimental results for the purpose of predicting accurate behavior. This study also focuses on the material constitutive model that is able to reproduce the inherent behavior of superelastic SMA materials by taking phase transformation between austenite and martensite into consideration. The responses of SMA slit dampers are compared to those of steel slit dampers. Axial stress and strain components are also investigated on the FE models under cyclic loading in an effort to validate the adequacy of FE modeling and then to compare between two slit damper systems. It can be shown that SMA slit dampers exhibit many structural advantages in terms of ultimate strength, moderate energy dissipation and recentering capability.

Wear-dependent specific coefficients in a mechanistic model for turning of nickel-based superalloy with ceramic tools

Directory of Open Access Journals (Sweden)

López de Lacalle Luis Norberto

2017-09-01

Full Text Available Difficult to cut materials such as nickel and titanium alloys are used in the aeronautical industry, the former alloys due to its heat-resistant behavior and the latter for the low weight - high strength ratio. Ceramic tools made out alumina with reinforce SiC whiskers are a choice in turning for roughing and semifinishing workpiece stages. Wear rate is high in the machining of these alloys, and consequently cutting forces tends to increase along one operation.

Nickel hydrogen/nickel cadmium battery trade studies

Science.gov (United States)

Stadnick, S. J.

1983-01-01

Nickel Hydrogen cell and battery technology has matured to the point where a real choice exists between Nickel Hydrogen and Nickel Cadmium batteries for each new spacecraft application. During the past few years, a number of spacecraft programs have been evaluated at Hughes with respect to this choice, with the results being split about fifty-fifty. The following paragraphs contain criteria which were used in making the battery selection.

NICKEL PLATING PROCESS

Science.gov (United States)

Hoover, T.B.; Zava, T.E.

1959-05-12

A simplified process is presented for plating nickel by the vapor decomposition of nickel carbonyl. In a preferred form of the invention a solid surface is nickel plated by subjecting the surface to contact with a mixture containing by volume approximately 20% nickel carbonyl vapor, 2% hydrogen sulfide and .l% water vapor or 1% oxygen and the remainder carbon dioxide at room temperature until the desired thickness of nickel is obtained. The advantage of this composition over others is that the normally explosive nickel carbonyl is greatly stabilized.

Carbon deposition on nickel ferrites and nickel-magnetite surfaces

International Nuclear Information System (INIS)

Allen, G.C.; Jutson, J.A.

1988-06-01

Carbon deposition on Commercial Advanced Gas-Cooled Reactor (CAGR) fuel cladding and heat exchanger surfaces lowers heat transfer efficiency and increases fuel pin temperatures. Several types of deposit have been identified including both thin dense layers and also low density columnar deposits with filamentary or convoluted laminar structure. The low-density types are often associated with particles containing iron, nickel or manganese. To identify the role of nickel in the deposition process surfaces composed of nickel-iron spinels or metallic nickel/magnetite mixtures have been exposed to γ radiation in a gas environment simulating that in the reactor. Examination of these surfaces by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) have shown that while metallic nickel (Ni(O)) catalyses the formation of filamentary low density carbon deposits, the presence of divalent nickel (Ni(II)) sites in spinel type oxides is associated only with dense deposits. (author)

The EU Nickel Directive revisited--future steps towards better protection against nickel allergy

DEFF Research Database (Denmark)

Thyssen, Jacob P; Uter, Wolfgang; McFadden, John

2011-01-01

In July 2001, the EU Nickel Directive came into full force to protect European citizens against nickel allergy and dermatitis. Prior to this intervention, Northern European governments had already begun to regulate consumer nickel exposure. According to part 2 of the EU Nickel Directive and the D......In July 2001, the EU Nickel Directive came into full force to protect European citizens against nickel allergy and dermatitis. Prior to this intervention, Northern European governments had already begun to regulate consumer nickel exposure. According to part 2 of the EU Nickel Directive...... and the Danish nickel regulation, consumer items intended to be in direct and prolonged contact with the skin were not allowed to release more than 0.5 µg nickel/cm2/week. It was considered unlikely that nickel allergy would disappear altogether as a proportion of individuals reacted below the level defined...

Hardness and Microstructure of Binary and Ternary Nitinol Compounds

Science.gov (United States)

Stanford, Malcolm K.

2016-01-01

The hardness and microstructure of twenty-six binary and ternary Nitinol (nickel titanium, nickel titanium hafnium, nickel titanium zirconium and nickel titanium tantalum) compounds were studied. A small (50g) ingot of each compound was produced by vacuum arc remelting. Each ingot was homogenized in vacuum for 48 hr followed by furnace cooling. Specimens from the ingots were then heat treated at 800, 900, 1000 or 1100 degree C for 2 hr followed by water quenching. The hardness and microstructure of each specimen was compared to the baseline material (55-Nitinol, 55 at.% nickel - 45 at.% titanium, after heat treatment at 900 degC). The results show that eleven of the studied compounds had higher hardness values than the baseline material. Moreover, twelve of the studied compounds had measured hardness values greater 600HV at heat treatments from 800 to 900 degree C.

Incidence of apical crack formation and propagation during removal of root canal filling materials with different engine driven nickel-titanium instruments

Directory of Open Access Journals (Sweden)

Taha Özyürek

2017-11-01

Full Text Available Objectives To determine the incidence of crack formation and propagation in apical root dentin after retreatment procedures performed using ProTaper Universal Retreatment (PTR, Mtwo-R, ProTaper Next (PTN, and Twisted File Adaptive (TFA systems. Materials and Methods The study consisted of 120 extracted mandibular premolars. One millimeter from the apex of each tooth was ground perpendicular to the long axis of the tooth, and the apical surface was polished. Twenty teeth served as the negative control group. One hundred teeth were prepared, obturated, and then divided into 5 retreatment groups. The retreatment procedures were performed using the following files: PTR, Mtwo-R, PTN, TFA, and hand files. After filling material removal, apical enlargement was done using apical size 0.50 mm ProTaper Universal (PTU, Mtwo, PTN, TFA, and hand files. Digital images of the apical root surfaces were recorded before preparation, after preparation, after obturation, after filling removal, and after apical enlargement using a stereomicroscope. The images were then inspected for the presence of new apical cracks and crack propagation. Data were analyzed with χ2 tests using SPSS 21.0 software. Results New cracks and crack propagation occurred in all the experimental groups during the retreatment process. Nickel-titanium rotary file systems caused significantly more apical crack formation and propagation than the hand files. The PTU system caused significantly more apical cracks than the other groups after the apical enlargement stage. Conclusions This study showed that retreatment procedures and apical enlargement after the use of retreatment files can cause crack formation and propagation in apical dentin.

En-masse retraction with a preformed nickel-titanium and stainless steel archwire assembly and temporary skeletal anchorage devices without posterior bonding.

Science.gov (United States)

Jee, Jeong-Hyun; Ahn, Hyo-Won; Seo, Kyung-Won; Kim, Seong-Hun; Kook, Yoon-Ah; Chung, Kyu-Rhim; Nelson, Gerald

2014-09-01

To evaluate the therapeutic effects of a preformed assembly of nickel-titanium (NiTi) and stainless steel (SS) archwires (preformed C-wire) combined with temporary skeletal anchorage devices (TSADs) as the sole source of anchorage and to compare these effects with those of a SS version of C-wire (conventional C-wire) for en-masse retraction. Thirty-one adult female patients with skeletal Class I or II dentoalveolar protrusion, mild-to-moderate anterior crowding (3.0-6.0 mm), and stable Class I posterior occlusion were divided into conventional (n = 15) and preformed (n = 16) C-wire groups. All subjects underwent first premolar extractions and en-masse retraction with pre-adjusted edgewise anterior brackets, the assigned C-wire, and maxillary C-tubes or C-implants; bonded mesh-tube appliances were used in the mandibular dentition. Differences in pretreatment and post-retraction measurements of skeletal, dental, and soft-tissue cephalometric variables were statistically analyzed. Both groups showed full retraction of the maxillary anterior teeth by controlled tipping and space closure without altered posterior occlusion. However, the preformed C-wire group had a shorter retraction period (by 3.2 months). Furthermore, the maxillary molars in this group showed no significant mesialization, mesial tipping, or extrusion; some mesialization and mesial tipping occurred in the conventional C-wire group. Preformed C-wires combined with maxillary TSADs enable simultaneous leveling and space closure from the beginning of the treatment without maxillary posterior bonding. This allows for faster treatment of dentoalveolar protrusion without unwanted side effects, when compared with conventional C-wire, evidencing its clinical expediency.

Incidence of apical crack formation and propagation during removal of root canal filling materials with different engine driven nickel-titanium instruments.

Science.gov (United States)

Özyürek, Taha; Tek, Vildan; Yılmaz, Koray; Uslu, Gülşah

2017-11-01

To determine the incidence of crack formation and propagation in apical root dentin after retreatment procedures performed using ProTaper Universal Retreatment (PTR), Mtwo-R, ProTaper Next (PTN), and Twisted File Adaptive (TFA) systems. The study consisted of 120 extracted mandibular premolars. One millimeter from the apex of each tooth was ground perpendicular to the long axis of the tooth, and the apical surface was polished. Twenty teeth served as the negative control group. One hundred teeth were prepared, obturated, and then divided into 5 retreatment groups. The retreatment procedures were performed using the following files: PTR, Mtwo-R, PTN, TFA, and hand files. After filling material removal, apical enlargement was done using apical size 0.50 mm ProTaper Universal (PTU), Mtwo, PTN, TFA, and hand files. Digital images of the apical root surfaces were recorded before preparation, after preparation, after obturation, after filling removal, and after apical enlargement using a stereomicroscope. The images were then inspected for the presence of new apical cracks and crack propagation. Data were analyzed with χ 2 tests using SPSS 21.0 software. New cracks and crack propagation occurred in all the experimental groups during the retreatment process. Nickel-titanium rotary file systems caused significantly more apical crack formation and propagation than the hand files. The PTU system caused significantly more apical cracks than the other groups after the apical enlargement stage. This study showed that retreatment procedures and apical enlargement after the use of retreatment files can cause crack formation and propagation in apical dentin.

Electrolytic Recovery of Nickel from Spent Electroless Nickel Bath Solution

Directory of Open Access Journals (Sweden)

R. Idhayachander

2010-01-01

Full Text Available Plating industry is one of the largest polluting small scale industries and nickel plating is among the important surface finishing process in this industry. The waste generated during this operation contains toxic nickel. Nickel removal and recovery is of great interest from spent bath for environmental and economic reasons. Spent electroless nickel solution from a reed relay switch manufacturing industry situated in Chennai was taken for electrolytic recovery of nickel. Electrolytic experiment was carried out with mild steel and gold coated mild steel as cathode and the different parameters such as current density, time, mixing and pH of the solution were varied and recovery and current efficiency was studied. It was noticed that there was an increase in current efficiency up to 5 A/dm2 and after that it declines. There is no significant improvement with mixing but with modified cathode there was some improvement. Removal of nickel from the spent electroless nickel bath was 81.81% at 5 A/dm2 and pH 4.23. Under this condition, the content of nickel was reduced to 0.94 g/L from 5.16 g/L. with 62.97% current efficiency.

Human exposure to nickel

Energy Technology Data Exchange (ETDEWEB)

Grandjean, P

1984-01-01

In order of abundance in the earth's crust, nickel ranks as the 24th element and has been detected in different media in all parts of the biosphere. Thus, humans are constantly exposed to this ubiquitous element, though in variable amounts. Occupational exposures may lead to the retention of 100 micrograms of nickel per day. Environmental nickel levels depend particularly on natural sources, pollution from nickel-manufacturing industries and airborne particles from combustion of fossil fuels. Absorption from atmospheric nickel pollution is of minor concern. Vegetables usually contain more nickel than do other food items. Certain products, such as baking powder and cocoa powder, have been found to contain excessive amounts of nickel, perhaps related to nickel leaching during the manufacturing process. Soft drinking-water and acid beverages may dissolve nickel from pipes and containers. Scattered studies indicate a highly variable dietary intake of nickel, but most averages are about 200-300 micrograms/day. In addition, skin contact to a multitude of metal objects may be of significance to the large number of individuals suffering from contact dermatitis and nickel allergy. Finally, nickel alloys are often used in nails and prostheses for orthopaedic surgery, and various sources may contaminate intravenous fluids. Thus, human nickel exposure originates from a variety of sources and is highly variable. Occupational nickel exposure is of major significance, and leaching of nickel may add to dietary intakes and to cutaneous exposures. 79 references.

Synthesis of Nickel and Nickel Hydroxide Nanopowders by Simplified Chemical Reduction

Directory of Open Access Journals (Sweden)

Jeerapan Tientong

2014-01-01

Full Text Available Nickel nanopowders were synthesized by a chemical reduction of nickel ions with hydrazine hydrate at pH ~12.5. Sonication of the solutions created a temperature of 54–65°C to activate the reduction reaction of nickel nanoparticles. The solution pH affected the composition of the resulting nanoparticles. Nickel hydroxide nanoparticles were formed from an alkaline solution (pH~10 of nickel-hydrazine complexed by dropwise titration. X-ray diffraction of the powder and the analysis of the resulting Williamson-Hall plots revealed that the particle size of the powders ranged from 12 to 14 nm. Addition of polyvinylpyrrolidone into the synthesis decreased the nickel nanoparticle size to approximately 7 nm. Dynamic light scattering and scanning electron microscopy confirmed that the particles were in the nanometer range. The structure of the synthesized nickel and nickel hydroxide nanoparticles was identified by X-ray diffraction and Fourier transform infrared spectroscopy.

Innovative coatings and surface modification of titanium for sea water condenser applications

International Nuclear Information System (INIS)

George, R.P.; Anandkumar, B.; Vanithakumari, S.C.; Kamachi Mudali, U.

2016-01-01

Effectiveness of cooling water systems in various power plants to maintain highest electrical energy output per tonne of fuel is important as part of good energy management. Cooling water systems of nuclear power plants using seawater for cooling comes under constant attack from the marine and sea water environment. Many metallic components and civil structures in the cooling water systems like bridges, intake wells, intake pipes, pump house wells, water boxes, condenser pipes are subjected to severe fouling and corrosion which limits the service life and availability of power plants. The experience with a coastal water cooled power plant at Kalpakkam (MAPS), India, showed that chlorination and screening control macrofouling to a great extend by controlling protozoans, invertebrates, algae and fungi. However 90% of marine bacteria are resistant to such control measures, and they cause microfouling of condenser pipes leading to poor heat transfer and microbially influenced corrosion (MIC) failures. Titanium is used as condenser for Indian nuclear power plants employing sea water cooling, including the PFBR at Kalpakkam. Though titanium is excellent with respect to corrosion behavior under sea water conditions, its biocompatible nature results in biofouling and MIC during service. Therefore innovative antifouling coatings and surface modification techniques for titanium condenser applications in seawater and marine environments are the need of the hour. Extensive investigations were carried out by different methods including nanostructuring of surfaces for making them antibacterial. The microroughness of titanium was produced by repeated pickling and polishing which by itself reduced microbial adhesion. To utilize photocatalytic activity for antibacterial property, anodization of titanium surfaces followed by heat treatment was adopted and this also has controlled microbial fouling. Electroless plating of nanofilm of copper-nickel alloy decreased biofouling of

The EU Nickel Directive revisited--future steps towards better protection against nickel allergy

DEFF Research Database (Denmark)

Thyssen, Jacob P; Uter, Wolfgang; McFadden, John

2011-01-01

In July 2001, the EU Nickel Directive came into full force to protect European citizens against nickel allergy and dermatitis. Prior to this intervention, Northern European governments had already begun to regulate consumer nickel exposure. According to part 2 of the EU Nickel Directive...... by the EU Nickel Directive. Despite this, the EU Nickel Directive part 2 was expected to work as an operational limit that would sufficiently protect European consumers against nickel allergy and dermatitis. This review presents the accumulation of epidemiological studies that evaluated the possible effect...... and the Danish nickel regulation, consumer items intended to be in direct and prolonged contact with the skin were not allowed to release more than 0.5 µg nickel/cm2/week. It was considered unlikely that nickel allergy would disappear altogether as a proportion of individuals reacted below the level defined...

Release of nickel and chromium ions from orthodontic wires following the use of teeth whitening mouthwashes

Directory of Open Access Journals (Sweden)

AmirHossein Mirhashemi

2018-02-01

Full Text Available Abstract Background Corrosion resistance is an important requirement for orthodontic appliances. Nickel and chromium may be released from orthodontic wires and can cause allergic reactions and cytotoxicity when patients use various mouthwashes to whiten their teeth. Our study aimed to assess the release of nickel and chromium ions from nickel titanium (NiTi and stainless steel (SS orthodontic wires following the use of four common mouthwashes available on the market. Methods This in vitro, experimental study was conducted on 120 orthodontic appliances for one maxillary quadrant including five brackets, one band and half of the required length of SS, and NiTi wires. The samples were immersed in Oral B, Oral B 3D White Luxe, Listerine, and Listerine Advance White for 1, 6, 24, and 168 h. The samples immersed in distilled water served as the control group. Atomic absorption spectroscopy served to quantify the amount of released ions. Results Nickel ions were released from both wires at all time-points; the highest amount was in Listerine and the lowest in Oral B mouthwashes. The remaining two solutions were in-between this range. The process of release of chromium from the SS wire was the same as that of nickel. However, the release trend in NiTi wires was not uniform. Conclusions Listerine caused the highest release of ions. Listerine Advance White, Oral B 3D White Luxe, and distilled water were the same in terms of ion release. Oral B showed the lowest amount of ion release.

Orientation dependence and tension/compression asymmetry of shape memory effect and superelasticity in ferromagnetic Co40Ni33Al27, Co49Ni21Ga30 and Ni54Fe19Ga27 single crystals

International Nuclear Information System (INIS)

Chumlyakov, Y.; Panchenko, E.; Kireeva, I.; Karaman, I.; Sehitoglu, H.; Maier, H.J.; Tverdokhlebova, A.; Ovsyannikov, A.

2008-01-01

In the present study the effects of crystal axis orientation, stress state (tension/compression) and test temperature on shape memory effect and superelasticity of Ni 54 Fe 19 Ga 27 (I), Co 40 Ni 33 Al 27 (II), Co 49 Ni 21 Ga 30 (III) (numbers indicate at.%) single crystals were investigated. The shape memory effect, the start temperature of superelasticity T 1 and the mechanical hysteresis Δσ were found to be dependent on crystal axis orientation and stress state. Superelasticity was observed at T 1 = A f (A f , reverse transformation-finish temperature) in tension/compression for [0 0 1]-oriented Ni-Fe-Ga crystals and in compression for [0 0 1]-oriented Co-Ni-Ga crystals, which all displayed a small mechanical hysteresis (Δσ ≤ 30 MPa). An increase in Δσ of up to 90 MPa in the Co-Ni-Al and the Co-Ni-Ga crystals lead to stabilization of the stress-induced martensite, and an increase in to T 1 = A f + Δ. The maximal value of Δ (75 K) was found in [0 0 1]-oriented Co-Ni-Al crystals in tension. A thermodynamic criterion describing the dependencies of the start temperature of superelasticity T 1 on crystal axis orientation, stress state and the magnitude of mechanical hysteresis is discussed

Improvements of anti-corrosion and mechanical properties of NiTi orthopedic materials by acetylene, nitrogen and oxygen plasma immersion ion implantation

International Nuclear Information System (INIS)

Poon, Ray W.Y.; Ho, Joan P.Y.; Liu Xuanyong; Chung, C.Y.; Chu, Paul K.; Yeung, Kelvin W.K.; Lu, William W.; Cheung, Kenneth M.C.

2005-01-01

Nickel-titanium shape memory alloys (NiTi) are useful materials in orthopedics and orthodontics due to their unique super-elasticity and shape memory effects. However, the problem associated with the release of harmful Ni ions to human tissues and fluids has been raising safety concern. Hence, it is necessary to produce a surface barrier to impede the out-diffusion of Ni ions from the materials. We have conducted acetylene, nitrogen and oxygen plasma immersion ion implantation (PIII) into NiTi alloys in an attempt to improve the surface properties. All the implanted and annealed samples surfaces exhibit outstanding corrosion and Ni out-diffusion resistance. Besides, the implanted layers are mechanically stronger than the substrate underneath. XPS analyses disclose that the layer formed by C 2 H 2 PIII is composed of mainly TiC x with increasing Ti to C concentration ratios towards the bulk. The nitrogen PIII layer is observed to be TiN, whereas the oxygen PIII layer is composed of oxides of Ti 4+ , Ti 3+ and Ti 2+

Oral nickel exposure may induce Type I hypersensitivity reaction in nickel-sensitized subjects.

Science.gov (United States)

Büyüköztürk, Suna; Gelincik, Aslı; Ünal, Derya; Demirtürk, Mustafa; Çelik, Dolay Damla; Erden, Sacide; Çolakoğlu, Bahattin; Erdem Kuruca, Serap

2015-05-01

Little is known about the clinical and immunological changes in the nickel allergic patients with systemic symptoms. We aimed to evaluate T helper cell responses of patients with different clinical presentations due to nickel. Patients having various allergic symptoms and positive patch test results to nickel and 20 controls underwent skin prick tests with nickel. IL-10, IL-4, IL-5 and IFN-gamma were measured in the culture supernatants of PBMC stimulated by nickel during lymphocyte proliferation test (LTT). 69 patients (56 female, mean age: 49.2 ± 13.1), 97% having nickel containing dental devices and 20 controls (8 female, mean age 34.9 ± 12.06) were evaluated. Skin prick tests with nickel were positive in 70% of the patients (pnickel. Nickel containing dental alloys and oral nickel intake seem to trigger systemic symptoms in previously nickel sensitized patients. Copyright © 2015 Elsevier B.V. All rights reserved.

Excessive nickel release from mobile phones--a persistent cause of nickel allergy and dermatitis.

Science.gov (United States)

Jensen, Peter; Johansen, Jeanne D; Zachariae, Claus; Menné, Torkil; Thyssen, Jacob P

2011-12-01

Despite the political intention to limit nickel allergy and dermatitis in Europeans, nickel allergy remains frequent. There are several explanations for the persistence of nickel allergy and dermatitis, including the increasing use of mobile phones. Before regulation of nickel release from mobile phones, we showed that eight (19.5%) of 41 mobile phones marketed in Denmark between 2003 and 2007 released nickel in concentrations that may result in nickel allergy and dermatitis. In 2009, the EU Nickel Directive was revised to include nickel-releasing mobile phones. To investigate the proportion of mobile phones sold in Denmark that release nickel after regulation. Metallic parts from 50 randomly selected mobile phones currently for sale in Denmark were tested for nickel release by use of the dimethylglyoxime (DMG)-nickel spot test. Nine (18%) phones showed at least one positive DMG test reaction and two phones had more than one DMG test-positive spot. Apparently, the proportion of mobile phones with significant nickel release remains unchanged, despite the 2009 revision of the EU Nickel Directive. We encourage manufacturers to measure nickel release from metallic components used in the assembly of mobile phones to ensure safe products. © 2011 John Wiley & Sons A/S.

Negative and Zero Thermal Expansion NiTi Superelastic Shape Memory Alloy by Microstructure Engineering

Science.gov (United States)

Sun, Qingping; Yu, Chao; Kang, Guozheng

2018-03-01

We report recent progress in tailoring the thermal expansion (TE) of nanocrystalline (NC) NiTi by microstructure hierarchical design and control without composition change. Fabrication and characterization methods are outlined and preliminary results of both experiment and mechanism-based modeling are presented to understand and get insight into the unusual TE phenomena. The important roles of the intrinsic thermal expansion anisotropy of B19' lattice and the suppression of phase transition by the extrinsic fabricated microstructure (cold rolling and annealing, grain size, defects, textures and volume fractions of nanoscaled B2 and B19' lattices) in the overall macroscopic TE behaviors of the superelastic NC NiTi polycrystal SMAs are emphasized.

Negative and Zero Thermal Expansion NiTi Superelastic Shape Memory Alloy by Microstructure Engineering

Science.gov (United States)

Sun, Qingping; Yu, Chao; Kang, Guozheng

2018-02-01

We report recent progress in tailoring the thermal expansion (TE) of nanocrystalline (NC) NiTi by microstructure hierarchical design and control without composition change. Fabrication and characterization methods are outlined and preliminary results of both experiment and mechanism-based modeling are presented to understand and get insight into the unusual TE phenomena. The important roles of the intrinsic thermal expansion anisotropy of B19' lattice and the suppression of phase transition by the extrinsic fabricated microstructure (cold rolling and annealing, grain size, defects, textures and volume fractions of nanoscaled B2 and B19' lattices) in the overall macroscopic TE behaviors of the superelastic NC NiTi polycrystal SMAs are emphasized.

Effectiveness of supplementary irrigant agitation with the Finisher GF Brush on the debridement of oval root canals instrumented with the Gentlefile or nickel titanium rotary instruments.

Science.gov (United States)

Neelakantan, P; Khan, K; Li, K Y; Shetty, H; Xi, W

2018-07-01

To examine the efficacy of a novel supplementary irrigant agitating brush (Finisher GF Brush, MedicNRG, Kibbutz Afikim, Israel) on the debridement of root canals prepared with a novel stainless steel rotary instrumentation system (Gentlefile; MedicNRG), or nickel titanium rotary instruments in oval root canals. Mandibular premolars (n = 72) were selected and divided randomly into three experimental groups (n = 24) after microCT scanning: group 1, canal preparation to rotary NiTi size 20, .04 taper (R20); group 2, rotary NiTi to size 25, .04 taper (R25) and group 3, Gentlefile size 23, .04 taper (GF). Specimens were subdivided into two subgroups: subgroup A, syringe-and-needle irrigation (SNI); subgroup B, Finisher GF Brush (GB). Ten untreated canals served as controls. Specimens were processed for histological evaluation, and the remaining pulp tissue (RPT) was measured. Data were analysed using Mann-Whitney and Kruskal-Wallis tests (P = 0.05). All experimental groups had significantly less RPT than the control (P  0.05). When instrumented with R20, there was no significant difference between SNI and GF (P rotary NiTi. Root canal debridement did not significantly differ between the instruments when syringe irrigation was used. © 2018 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Sealing glasses for titanium and titanium alloys

Science.gov (United States)

Brow, Richard K.; McCollister, Howard L.; Phifer, Carol C.; Day, Delbert E.

1997-01-01

Barium lanthanoborate sealing-glass compositions are provided comprising various combinations (in terms of mole-%) of boron oxide (B.sub.2 O.sub.3), barium oxide (BaO), lanthanum oxide (La.sub.2 O.sub.3), and at least one other oxide selected from the group consisting of aluminum oxide (Al.sub.2 O.sub.3), calcium oxide (CaO), lithium oxide (Li.sub.2 O), sodium oxide (Na.sub.2 O), silicon dioxide (SiO.sub.2), or titanium dioxide (TiO.sub.2). These sealing-glass compositions are useful for forming hermetic glass-to-metal seals with titanium and titanium alloys having an improved aqueous durability and favorable sealing characteristics. Examples of the sealing-glass compositions are provided having coefficients of thermal expansion about that of titanium or titanium alloys, and with sealing temperatures less than about 900.degree. C., and generally about 700.degree.-800.degree. C. The barium lanthanoborate sealing-glass compositions are useful for components and devices requiring prolonged exposure to moisture or water, and for implanted biomedical devices (e.g. batteries, pacemakers, defibrillators, pumps).

Excessive nickel release from mobile phones--a persistent cause of nickel allergy and dermatitis

DEFF Research Database (Denmark)

Jensen, Peter; Johansen, Jeanne D; Zachariae, Claus

2011-01-01

Despite the political intention to limit nickel allergy and dermatitis in Europeans, nickel allergy remains frequent. There are several explanations for the persistence of nickel allergy and dermatitis, including the increasing use of mobile phones. Before regulation of nickel release from mobile...... phones, we showed that eight (19.5%) of 41 mobile phones marketed in Denmark between 2003 and 2007 released nickel in concentrations that may result in nickel allergy and dermatitis. In 2009, the EU Nickel Directive was revised to include nickel-releasing mobile phones....

Excessive nickel release from mobile phones--a persistent cause of nickel allergy and dermatitis

DEFF Research Database (Denmark)

Jensen, Peter; Johansen, Jeanne D; Zachariae, Claus

2011-01-01

phones, we showed that eight (19.5%) of 41 mobile phones marketed in Denmark between 2003 and 2007 released nickel in concentrations that may result in nickel allergy and dermatitis. In 2009, the EU Nickel Directive was revised to include nickel-releasing mobile phones.......Despite the political intention to limit nickel allergy and dermatitis in Europeans, nickel allergy remains frequent. There are several explanations for the persistence of nickel allergy and dermatitis, including the increasing use of mobile phones. Before regulation of nickel release from mobile...

Synthesis of Nickel and Nickel Hydroxide Nano powders by Simplified Chemical Reduction

International Nuclear Information System (INIS)

Tientong, J.; Garcia, S.; Thurber, C.R.; Golden, T.D.

2014-01-01

Nickel nano powders were synthesized by a chemical reduction of nickel ions with hydrazine hydrate at ph ∼ 12.5. Sonication of the solutions created a temperature of 54-65 °C to activate the reduction reaction of nickel nanoparticles. The solution ph affected the composition of the resulting nanoparticles. Nickel hydroxide nanoparticles were formed from an alkaline solution (ph ∼10) of nickel-hydrazine complexed by dropwise titration. X-ray diffraction of the powder and the analysis of the resulting Williamson-Hall plots revealed that the particle size of the powders ranged from 12 to 14 nm. Addition of polyvinylpyrrolidone into the synthesis decreased the nickel nanoparticle size to approximately 7 nm. Dynamic light scattering and scanning electron microscopy confirmed that the particles were in the nanometer range. The structure of the synthesized nickel and nickel hydroxide nanoparticles was identified by X-ray diffraction and Fourier transform infrared spectroscopy.

Comparative study of 6 rotary nickel-titanium systems and hand instrumentation for root canal preparation in severely curved root canals of extracted teeth.

Science.gov (United States)

Celik, Davut; Taşdemir, Tamer; Er, Kürşat

2013-02-01

Some improvements have been developed with new generations of nickel-titanium (NiTi) rotary instruments that led to their successful and extensive application in clinical practice. The purpose of this in vitro study was to compare the root canal preparations performed by using GT Series X and Twisted File systems produced by innovative manufacturing process with Revo-S, RaCe, Mtwo, and ProTaper Universal systems manufactured directly from conventional nitinol and with stainless steel K-Flexofile instruments. The mesiobuccal root canals of 140 maxillary first permanent molars that had between 30°-40° curvature angle and 4- to 9-mm curvature radius of the root canal were used. After root canal preparations made by using GT Series X, Twisted File, Revo-S, RaCe, Mtwo, and ProTaper Universal NiTi rotary systems and stainless steel K-Flexofile instruments, transportation occurred in the root canal, and alteration of working length (WL) was assessed by using a modified double-digital radiographic technique. The data were compared by the post hoc Tukey honestly significant difference test. NiTi rotary systems caused less canal transportation and alteration of WL than K-Flexofile instruments (P .05) except 2.5 mm from the WL. At this level ProTaper Universal system caused significant canal transportation (P ProTaper Universal rotary systems manufactured by traditional methods. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Nickel concentrations in fingernails as a measure of occupational exposure to nickel

DEFF Research Database (Denmark)

Peters, K; Gammelgaard, Bente; Menné, T

1991-01-01

in nails (p less than 0.001). The difference between the 2 levels was also significant (p less than 0.001). No correlation between the nickel concentration in fingernails and the duration of exposure could be demonstrated. It was concluded that the higher the nickel level in the fingernails, the greater...... is the possibility that the person is occupationally exposed to nickel. Nail analysis is suggested as a measure of occupational exposure to nickel.......The nickel concentration in fingernails from 2 groups of people occupationally exposed to nickel was determined. In one group, comprising 83 persons moderately exposed to nickel, the mean +/- standard deviation (SD) was 29.2 micrograms/g +/- 56.7 micrograms/g and the median 13.8 micrograms/g (range...

Assessment of chemical composition and microbiological properties of titanium nickelide supernatant

Directory of Open Access Journals (Sweden)

Uruzbaev R.M.

2018-03-01

Full Text Available According to the World Health Organization, in the structure of internal injuries, burns occur in 2.1 per 1000 adults. In practice, all victims after stabilization of the condition are treated surgically with the autodermoplasty, which in the late period is accompanied by a rough scarring, sometimes with the deformation of the damaged area. In addition, infectious complications worsen and aggravate the wound healing process, and also significantly prolong the epithelialization time. A wound is usually infected by opportunistic pathogenic microflora resistant to various groups of antibiotics and antiseptics, by which the affected areas are treated. Modern researches are aimed at finding ways to accelerate regenerative processes of the affected area, to avoid surgical treatment and prevent infection contamination. The object of this study was titanium nickelide supernatant. Currently, there are no published data on the chemical composition of the supernatant, as well as its microbiological safety. This alloy is actively and successfully used in traumatology, dentistry and other fields of medicine. The supernatant was prepared under sterile conditions at a rate of 10 g of titanium nickelide powder per 1 liter of distilled water. In the course of the studies it was proved that nickel and titanium ions are present in the solution, in addition, its bactericidal and bacteriostatic properties are reflected. Thus, the supernatant of nitinol can be used in biological environment and is safe for them.

Texture and superelastic behavior of cold-rolled TiNbTaZr alloy

International Nuclear Information System (INIS)

Wang Liqiang; Lu Weijie; Qin Jining; Zhang Fan; Zhang Di

2008-01-01

This work investigates the deformation texture and strain-induced α'' martensite texture of TiNbTaZr alloy during cold rolling. The alloy is rolled by 20% and 90% reductions without changing rolling direction. Textures of cold-rolled specimens are investigated by X-ray diffraction measurements. Besides {2 2 1} β β twinning texture, {1 0 0} β β texture is developed in the specimen with 20% reduction. In the 90% cold-rolled specimen, {1 0 0} β β texture appears along rolling direction and strain-induced α'' martensite texture tends to [0 1 0] and [0 0 1] directions along rolling direction (RD) and transverse direction (TD), respectively. Superelastic strain (ε SE ) exhibits higher value along RD and TD. Pure elastic strain (ε E ) shows higher value along RD and 45 deg. from RD

Surface modification of titanium and titanium alloys by ion implantation.

Science.gov (United States)

Rautray, Tapash R; Narayanan, R; Kwon, Tae-Yub; Kim, Kyo-Han

2010-05-01

Titanium and titanium alloys are widely used in biomedical devices and components, especially as hard tissue replacements as well as in cardiac and cardiovascular applications, because of their desirable properties, such as relatively low modulus, good fatigue strength, formability, machinability, corrosion resistance, and biocompatibility. However, titanium and its alloys cannot meet all of the clinical requirements. Therefore, to improve the biological, chemical, and mechanical properties, surface modification is often performed. In view of this, the current review casts new light on surface modification of titanium and titanium alloys by ion beam implantation. (c) 2010 Wiley Periodicals, Inc.

Gentamicin-Eluting Titanium Dioxide Nanotubes Grown on the Ultrafine-Grained Titanium.

Science.gov (United States)

Nemati, Sima Hashemi; Hadjizadeh, Afra

2017-08-01

Titanium (Ti)-based materials is the most appropriate choices for the applications as orthopedic and dental implants. In this regard, ultrafine-grained (UFG) titanium with an enhanced mechanical properties and surface energy has attracted more attention. Titanium dioxide (TiO 2 ) nanotubes grown on the titanium could enhance bone bonding, cellular response and are good reservoirs for loading drugs and antibacterial agents. This article investigates gentamicin loading into and release from the TiO 2 nanotubes, grown on the UFG compared to coarse-grained (CG) titanium substrate surfaces. Equal Channel Angular Pressing (ECAP) was employed to produce the UFG structure titanium. TiO 2 nanotubes were grown by the anodizing technique on both UFG and CG titanium substrate surfaces. Scanning electron microscopy (SEM) imaging confirmed TiO 2 nanotube growth on the surface. The UV-vis spectroscopy analysis results show that the amount of gentamicin load-release in the anodized UFG titanium sample is higher than that of CG one which can be explained in terms of thicker TiO 2 nanotube arrays layer formed on UFG sample. Moreover, the anodized UFG titanium samples released the drug in a longer time than CG (1 day for the UFG titanium vs. 3 h for the CG one). Regarding wettability analysis, anodized UFG titanium sample showed more enhanced hydrophilicity than CG counterpart. Therefore, the significantly smaller grain size of pure titanium provided by the ECAP technique coupled with appropriate subsequent anodization treatment not only offers a good combination of biocompatibility and adequate mechanical properties but also it provides a delayed release condition for gentamicin.

Facile one-pot synthesis of nickel-incorporated titanium dioxide/graphene oxide composites: Enhancement of photodegradation under visible-irradiation

Energy Technology Data Exchange (ETDEWEB)

Pham, Thanh-Truc [School of Chemical Engineering, University of Ulsan, Daehakro 93, Nam-gu, Ulsan 44610 (Korea, Republic of); Nguyen-Huy, Chinh [School of Energy and Chemical Engineering, UNIST, 50 UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan 44919 (Korea, Republic of); Shin, Eun Woo, E-mail: ewshin@ulsan.ac.kr [School of Chemical Engineering, University of Ulsan, Daehakro 93, Nam-gu, Ulsan 44610 (Korea, Republic of)

2016-07-30

Highlights: • Ni-incorporated TiO{sub 2}/graphene oxide materials were prepared by facile one-pot method. • Raman spectra identified a small fraction of NiTiO{sub 3} at high Ni containing materials. • Graphene oxide acted as adsorption sites and inhibited the agglomeration of Ni particles. • The formation of NiTiO{sub 3} at high Ni content improved photoactivity under visible light. - Abstract: Nickel (Ni)—incorporated titanium dioxide (TiO{sub 2})/graphene oxide composite photocatalysts were prepared by anchoring the TiO{sub 2} and Ni onto the surface of graphene oxide (GO) sheets by a straightforward microwave-assisted, one-pot method for the first time. The as-prepared composite photocatalysts with high Ni content (40–50 wt%) showed good adsorption capacity in the dark and high reaction rate constants under visible illumination while the composite photocatalysts with low Ni content (5–10 wt%) exhibited weak activity. An anatase phase, a small amount of rutile phase and Ni metal were detected using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Raman measurements identified a small fraction of NiTiO{sub 3} only at high Ni content. The formation of NiTiO{sub 3} and the increase in the specific surface area (SSA) for 40 and 50 wt% Ni-loaded catalysts improved the adsorption capacity and photocatalytic activity upon exposure to visible light, resulting in very effective removal of dye contaminants under visible light irradiation. Increasing the Ni content up to 40 and 50 wt% induced not only a structural change affording high porosity but also a narrowing of the band gap to 2.51 eV. Meanwhile, the presence of GO in the composite photocatalysts inhibited the agglomeration of Ni particles even at high Ni content, resulting in similar Ni particle sizes regardless of the Ni content. At the same time, Ni metal accelerated the reduction of the GO sheets, as evidenced by the Raman data.

Laser shape setting of superelastic nitinol wires: Functional properties and microstructure

Science.gov (United States)

Tuissi, Ausonio; Coduri, Mauro; Biffi, Carlo Alberto

Shape setting is one of the most important steps in the production route of Nitinol Shape Memory Alloys (SMAs), as it can fix the functional properties, such as the shape memory effect and the superelasticity (SE). The conventional method for making the shape setting is performed at 400-500∘C in furnaces. In this work, a laser beam was adopted for performing straight shape setting on commercially available austenitic Nitinol thin wires. The laser beam, at different power levels, was moved along the wire length for inducing the functional performances. Calorimetric, pseudo-elastic and microstructural features of the laser annealed wires were studied through differential scanning calorimetry, tensile testing and high energy X-ray diffraction, respectively. It can be stated that the laser technology can induce SE in thin Nitinol wires: the wire performances can be modulated in function of the laser power and improved functional properties can be obtained.

Characterization and assessment of dermal and inhalable nickel exposures in nickel production and primary user industries.

Science.gov (United States)

Hughson, G W; Galea, K S; Heim, K E

2010-01-01

The aim of this study was to measure the levels of nickel in the skin contaminant layer of workers involved in specific processes and tasks within the primary nickel production and primary nickel user industries. Dermal exposure samples were collected using moist wipes to recover surface contamination from defined areas of skin. These were analysed for soluble and insoluble nickel species. Personal samples of inhalable dust were also collected to determine the corresponding inhalable nickel exposures. The air samples were analysed for total inhalable dust and then for soluble, sulfidic, metallic, and oxidic nickel species. The workplace surveys were carried out in five different workplaces, including three nickel refineries, a stainless steel plant, and a powder metallurgy plant, all of which were located in Europe. Nickel refinery workers involved with electrolytic nickel recovery processes had soluble dermal nickel exposure of 0.34 microg cm(-2) [geometric mean (GM)] to the hands and forearms. The GM of soluble dermal nickel exposure for workers involved in packing nickel salts (nickel chloride hexahydrate, nickel sulphate hexahydrate, and nickel hydroxycarbonate) was 0.61 microg cm(-2). Refinery workers involved in packing nickel metal powders and end-user powder operatives in magnet production had the highest dermal exposure (GM = 2.59 microg cm(-2) soluble nickel). The hands, forearms, face, and neck of these workers all received greater dermal nickel exposure compared with the other jobs included in this study. The soluble nickel dermal exposures for stainless steel production workers were at or slightly above the limit of detection (0.02 microg cm(-2) soluble nickel). The highest inhalable nickel concentrations were observed for the workers involved in nickel powder packing (GM = 0.77 mg m(-3)), although the soluble component comprised only 2% of the total nickel content. The highest airborne soluble nickel exposures were associated with refineries using

En-masse retraction with a preformed nickel-titanium and stainless steel archwire assembly and temporary skeletal anchorage devices without posterior bonding

Science.gov (United States)

Jee, Jeong-Hyun; Ahn, Hyo-Won; Seo, Kyung-Won; Kook, Yoon-Ah; Chung, Kyu-Rhim; Nelson, Gerald

2014-01-01

Objective To evaluate the therapeutic effects of a preformed assembly of nickel-titanium (NiTi) and stainless steel (SS) archwires (preformed C-wire) combined with temporary skeletal anchorage devices (TSADs) as the sole source of anchorage and to compare these effects with those of a SS version of C-wire (conventional C-wire) for en-masse retraction. Methods Thirty-one adult female patients with skeletal Class I or II dentoalveolar protrusion, mild-to-moderate anterior crowding (3.0-6.0 mm), and stable Class I posterior occlusion were divided into conventional (n = 15) and preformed (n = 16) C-wire groups. All subjects underwent first premolar extractions and en-masse retraction with pre-adjusted edgewise anterior brackets, the assigned C-wire, and maxillary C-tubes or C-implants; bonded mesh-tube appliances were used in the mandibular dentition. Differences in pretreatment and post-retraction measurements of skeletal, dental, and soft-tissue cephalometric variables were statistically analyzed. Results Both groups showed full retraction of the maxillary anterior teeth by controlled tipping and space closure without altered posterior occlusion. However, the preformed C-wire group had a shorter retraction period (by 3.2 months). Furthermore, the maxillary molars in this group showed no significant mesialization, mesial tipping, or extrusion; some mesialization and mesial tipping occurred in the conventional C-wire group. Conclusions Preformed C-wires combined with maxillary TSADs enable simultaneous leveling and space closure from the beginning of the treatment without maxillary posterior bonding. This allows for faster treatment of dentoalveolar protrusion without unwanted side effects, when compared with conventional C-wire, evidencing its clinical expediency. PMID:25309863

Electrocontact material based on silver dispersion-strengthened by nickel, titanium, and zinc oxides

Science.gov (United States)

Zeer, G. M.; Zelenkova, E. G.; Belousov, O. V.; Beletskii, V. V.; Nikolaev, S. V.; Ledyaeva, O. N.

2017-09-01

Samples of a composite electrocontact material based on silver strengthened by the dispersed phases of zinc and titanium oxides have been investigated by the electron microscopy and energy dispersive X-ray spectroscopy. A uniform distribution of the oxide phases containing 2 wt % zinc oxide in the initial charge has been revealed. The increase in the amount of zinc oxide leads to an increase of the size of the oxide phases. It has been shown that at the zinc oxide content of 2 wt %, the minimum wear is observed in the process of electroerosion tests; at 3 wt %, an overheating and welding of the contacts are observed.

An in vitro evaluation of the accuracy of four electronic apex locators using stainless-steel and nickel-titanium hand files

Directory of Open Access Journals (Sweden)

Paras Mull Gehlot

2016-02-01

Full Text Available Objectives The purpose of this in vitro study was to evaluate the accuracy of working length (WL determination of four electronic apex locators (EALs, namely, Root ZX (RZX, Elements diagnostic unit and apex locator (ELE, SybronEndo Mini Apex locator (MINI and Propex pixi (PIXI using Stainless steel (SS and nickel-titanium (NiTi hand files. The null hypothesis was that there was no difference between canal length determination by SS and NiTi files of 4 EALs. Materials and Methods Sixty extracted, single rooted human teeth were decoronated and the canal orifice flared. The actual length (AL was assessed visually, and the teeth were embedded in an alginate model. The electronic length (EL measurements were recorded with all four EALs using SS and NiTi files at '0.5' reading on display. The differences between the AL and EL were compared. Results The results obtained with each EAL with SS and NiTi files were compared with AL. A paired sample t test showed that there was a statistical significant difference between EAL readings with SS and NiTi files for RZX and MINI (p < 0.05. The accuracy of RZX, ELE, MINI and PIXI within ± 0.5 mm of AL with SS/NiTi files were 93.3%/70%, 90%/91.7%, 95%/68.3%, and 83.3%/83.3%, respectively. Conclusions The results of this study indicate that Root ZX was statistically more accurate with NiTi files compared to SS files, while MINI was statistically more accurate with SS files compared to NiTi files. ELE and PIXI were not affected by the alloy type of the file used to determine WL.

Effect of electrical discharge machining on uranium-0.75 titanium and tungsten-3.5 nickel-1.5 iron alloys

International Nuclear Information System (INIS)

Anderson, R.C.

1976-06-01

It was found that U--0.75 Ti alloy cracked if the EDM parameters were out of control, and precipitation of carbides adjacent to the EDM surface took place during subsequent solution quenching. Cracks form in the ''recast'' layer when solution-quenched U--0.75 Ti alloy undergoes EDM, and the cracks propagated during subsequent nickel plating. If the recast layer was removed prior to nickel plating, only a slight loss in strength resulted, compared to conventional machining. W--3.5 Ni--1.5 Fe alloy also sustained some surface damage during EDM and also experienced a small loss in strength compared to conventionally machined material. 12 figures, 4 tables

Management of long-term and reversible hysteroscopic sterilization: a novel device with nickel-titanium shape memory alloy

Science.gov (United States)

2014-01-01

Background Female sterilization is the second most commonly used method of contraception in the United States. Female sterilization can now be performed through laparoscopic, abdominal, or hysteroscopic approaches. The hysteroscopic sterilization may be a safer option than sterilization through laparoscopy or laparotomy because it avoids invading the abdominal cavity and undergoing general anaesthesia. Hysteroscopic sterilization mainly includes chemical agents and mechanical devices. Common issues related to the toxicity of the chemical agents used have raised concerns regarding this kind of contraception. The difficulty of the transcervical insertion of such mechanical devices into the fallopian tubes has increased the high incidence of device displacement or dislodgment. At present, Essure® is the only commercially available hysteroscopic sterilization device being used clinically. The system is irreversible and is not effective immediately. Presentation of the hypothesis Our new hysteroscopic sterility system consists of nickel-titanium (NiTi) shape memory alloy and a waterproof membrane. The NiTi alloy is covered with two coatings to avoid toxic Ni release and to prevent stimulation of epithelial tissue growth around the oviducts. Because of the shape memory effect of the NiTi alloy, the device works like an umbrella: it stays collapsed at low temperature before placement and opens by the force of shape memory activated by the body temperature after it is inserted hysteroscopically into the interstitial tubal lumen. The rim of the open device will incise into interstitial myometrium during the process of unfolding. Once the device is fixed, it blocks the tube completely. When the patient no longer wishes for sterilization, the device can be closed by perfusing liquid with low temperature into the uterine cavity, followed by prospective hysteroscopic removal. After the device removal, the fallopian tube will revert to its physiological functions. Testing the

Development of a Micro-Fiber Nickel Electrode for Nickel-Hydrogen Cell

Science.gov (United States)

Britton, Doris L.

1996-01-01

The development of a high specific energy battery is one of the objectives of the lightweight nickel-hydrogen (NiH2) program at the NASA Lewis Research Center. The approach has been to improve the nickel electrode by continuing combined in-house and contract efforts to develop a more efficient and lighter weight electrode for the nickel-hydrogen fuel cell. Small fiber diameter nickel plaques are used as conductive supports for the nickel hydroxide active material. These plaques are commercial products and have an advantage of increased surface area available for the deposition of active materials. Initial tests include activation and capacity measurements at different discharge levels followed by half-cell cycle testing at 80 percent depth-of-discharge in a low Earth orbit regime. The electrodes that pass the initial tests are life cycle tested in a boiler plate nickel-hydrogen cell before flightweight designs are built and tested.

Biological role of nickel

Energy Technology Data Exchange (ETDEWEB)

Thauer, R K; Diekert, G; Schoenheit, P

1980-01-01

Several enzymes and one cofactor have recently been shown to contain nickel. For example, urease of jack beans has been found to be a nickel protein and factor F/sub 430/ from methanogenic bacteria to be a nickel tetrapyrrole. The biological role of nickel in several organisms is discussed.

Contaminated nickel scrap processing

International Nuclear Information System (INIS)

Compere, A.L.; Griffith, W.L.; Hayden, H.W.; Johnson, J.S. Jr.; Wilson, D.F.

1994-12-01

The DOE will soon choose between treating contaminated nickel scrap as a legacy waste and developing high-volume nickel decontamination processes. In addition to reducing the volume of legacy wastes, a decontamination process could make 200,000 tons of this strategic metal available for domestic use. Contaminants in DOE nickel scrap include 234 Th, 234 Pa, 137 Cs, 239 Pu (trace), 60 Co, U, 99 Tc, and 237 Np (trace). This report reviews several industrial-scale processes -- electrorefining, electrowinning, vapormetallurgy, and leaching -- used for the purification of nickel. Conventional nickel electrolysis processes are particularly attractive because they use side-stream purification of process solutions to improve the purity of nickel metal. Additionally, nickel purification by electrolysis is effective in a variety of electrolyte systems, including sulfate, chloride, and nitrate. Conventional electrorefining processes typically use a mixed electrolyte which includes sulfate, chloride, and borate. The use of an electrorefining or electrowinning system for scrap nickel recovery could be combined effectively with a variety of processes, including cementation, solvent extraction, ion exchange, complex-formation, and surface sorption, developed for uranium and transuranic purification. Selected processes were reviewed and evaluated for use in nickel side-stream purification. 80 refs

Residual stress in ion implanted titanium nitride studied by parallel beam glancing incidence x-ray diffraction

International Nuclear Information System (INIS)

Geist, D.E.; Perry, A.J.; Treglio, J.R.; Valvoda, V.; Rafaja, D.

1995-01-01

Ion implantation is known to increase the lifetime of cutting tools. Current theories are the increase in lifetime is caused by an increase in the residual stress, or by work hardening of the surface associated with the implantation. In this work the effect of ion implantation on the residual stress in titanium nitride coatings made by the standard industrial methods of chemical and physical vapor deposition (CVD and PVD) is studied. It is found in the as-received condition (unimplanted), the residual stress levels are near zero for CVD materials and highly compressive, of the order of 6 GPa, for PVD materials. Ion implantation has no effect on the residual stress in the coatings made by CVD. Nitrogen does increase the compressive residual stress by some 10% in the near surface regions of PVD coatings, while nickel-titanium dual metal ion implantation does not have any effect. It appears that the lifetime increase is not associated with residual stress effects

Prevalence of nickel allergy in Europe following the EU Nickel Directive - a review

DEFF Research Database (Denmark)

Ahlström, Malin G; Thyssen, Jacob P; Menné, Torkil

2017-01-01

.4% versus 19.8%) (p = 0.02), in female dermatitis patients aged ≤17 years (14.3% versus 29.2%) (p women: 20.2% versus 36.6%) (p men: 4.9% versus 6.6%) (p ..., and generally remained high, affecting 8-18% of the general population. A consistent pattern of decreasing prevalence of nickel allergy in some EU countries was observed, although the prevalence among young women remains high. Steps should be taken for better prevention of nickel allergy in EU countries.......Nickel contact allergy remains a problem in EU countries, despite the EU Nickel Directive. To study the prevalence of nickel allergy in EU countries following the implementation of the EU Nickel Directive, we performed a systematic search in PubMed for studies that examined the prevalence of nickel...

Contaminated nickel scrap processing

Energy Technology Data Exchange (ETDEWEB)

Compere, A.L.; Griffith, W.L.; Hayden, H.W.; Johnson, J.S. Jr.; Wilson, D.F.

1994-12-01

The DOE will soon choose between treating contaminated nickel scrap as a legacy waste and developing high-volume nickel decontamination processes. In addition to reducing the volume of legacy wastes, a decontamination process could make 200,000 tons of this strategic metal available for domestic use. Contaminants in DOE nickel scrap include {sup 234}Th, {sup 234}Pa, {sup 137}Cs, {sup 239}Pu (trace), {sup 60}Co, U, {sup 99}Tc, and {sup 237}Np (trace). This report reviews several industrial-scale processes -- electrorefining, electrowinning, vapormetallurgy, and leaching -- used for the purification of nickel. Conventional nickel electrolysis processes are particularly attractive because they use side-stream purification of process solutions to improve the purity of nickel metal. Additionally, nickel purification by electrolysis is effective in a variety of electrolyte systems, including sulfate, chloride, and nitrate. Conventional electrorefining processes typically use a mixed electrolyte which includes sulfate, chloride, and borate. The use of an electrorefining or electrowinning system for scrap nickel recovery could be combined effectively with a variety of processes, including cementation, solvent extraction, ion exchange, complex-formation, and surface sorption, developed for uranium and transuranic purification. Selected processes were reviewed and evaluated for use in nickel side-stream purification. 80 refs.

Nickel ferrule applicators: a source of nickel exposure in children.

Science.gov (United States)

Jacob, Sharon E; Silverberg, Jonathan I; Rizk, Christopher; Silverberg, Nanette

2015-01-01

Eye makeup has been investigated for nickel content and found to have no direct association with nickel allergy and cosmetic dermatitis. However, the tools used (e.g., eyelash curlers, hairdressing scissors, hair curlers, and eye shadow and makeup applicators) may be sources. Nickel is ubiquitous and a wide range of sources have been reported, and makeup applicators (ferrules) now join the list. © 2015 Wiley Periodicals, Inc.

Nickel allergy in a Danish population 25 years after the first nickel regulation

DEFF Research Database (Denmark)

Ahlström, Malin G; Menné, Torkil; Thyssen, Jacob P

2017-01-01

BACKGROUND: Nickel in metallic items has been regulated in Denmark since 1990; however, 10% of young Danish women are still sensitized to nickel. There is a need for continuous surveillance of the effect of regulation. OBJECTIVES: To identify current self-reported metallic exposures leading...... reactions within 30 min of contact were reported by 30.7% of patients. CONCLUSIONS: Nickel exposures that led to the implementation of a nickel regulation seem to persist. The durations of contact with metallic items to fall under the current REACH regulation of nickel correspond well with the results...... to dermatitis in nickel-allergic patients, and the minimum contact time needed for dermatitis to occur. METHODS: A questionnaire was sent to all patients who reacted positively to nickel sulfate 5% pet. within the last 5 years at the Department of Dermatology and Allergy, Gentofte Hospital. RESULTS...

Aqueous electrochemistry of precipitation-hardened nickel base alloys

International Nuclear Information System (INIS)

Hosoya, K.; Ballinger, R.; Prybylowski, J.; Hwang, I.S.

1990-11-01

An investigation has been conducted to explore the importance of local crack tip electrochemical processes in precipitation-hardened Ni-Cr-Fe alloys driven by galvanic couples between grain boundary precipitates and the local matrix. The electrochemical behavior of γ' [Ni 3 (Al,Ti)] has been determined as a function of titanium concentration, temperature, and solution pH. The electrochemical behavior of Ni-Cr-Fe solid solution alloys has been investigated as a function of chromium content for a series of 10 Fe-variable Cr (6--18%)-balance Ni alloys, temperature, and pH. The investigation was conducted in neutral and pH3 solutions over the temperature range 25--300 degree C. The results of the investigation show that the electrochemical behavior of these systems is a strong function of temperature and composition. This is especially true for the γ' [Ni 3 (Al,Ti)] system where a transition from active/passive behavior to purely active behavior and back again occurs over a narrow temperature range near 100 degree C. Behavior of this system was also found to be a strong function of titanium concentration. In all cases, the Ni 3 (Al,Ti) phase was active with respect to the matrix. The peak in activity near 100 degree C correlates well with accelerated crack growth in this temperature range, observed in nickel-base alloy X-750 heat treated to precipitate γ' on the grain boundaries. 20 refs., 23 figs., 3 tabs

Titanium metal: extraction to application

Energy Technology Data Exchange (ETDEWEB)

Gambogi, Joseph (USGS, Reston, VA); Gerdemann, Stephen J.

2002-09-01

In 1998, approximately 57,000 tons of titanium metal was consumed in the form of mill products (1). Only about 5% of the 4 million tons of titanium minerals consumed each year is used to produce titanium metal, with the remainder primarily used to produce titanium dioxide pigment. Titanium metal production is primarily based on the direct chlorination of rutile to produce titanium tetrachloride, which is then reduced to metal using the Kroll magnesium reduction process. The use of titanium is tied to its high strength-to-weight ratio and corrosion resistance. Aerospace is the largest application for titanium. In this paper, we discuss all aspects of the titanium industry from ore deposits through extraction to present and future applications. The methods of both primary (mining of ore, extraction, and purification) and secondary (forming and machining) operations will be analyzed. The chemical and physical properties of titanium metal will be briefly examined. Present and future applications for titanium will be discussed. Finally, the economics of titanium metal production also are analyzed as well as the advantages and disadvantages of various alternative extraction methods.

Titanium disilicide formation by sputtering of titanium on heated silicon substrate

Science.gov (United States)

Tanielian, M.; Blackstone, S.

1984-09-01

We have sputter deposited titanium on bare silicon substrates at elevated temperatures. We find that at a substrate temperature of about 515 °C titanium silicide is formed due to the reaction of the titanium with the Si. The resistivity of the silicide is about 15 μΩ cm and it is not etchable in a selective titanium etch. This process can have applications in low-temperature, metal-oxide-semiconductor self-aligned silicide formation for very large scale integrated

Relationship between nickel allergy and diet

Directory of Open Access Journals (Sweden)

Sharma Ashimav

2007-01-01

Full Text Available Nickel is a ubiquitous trace element and it occurs in soil, water, air and of the biosphere. It is mostly used to manufacture stainless steel. Nickel is the commonest cause of metal allergy. Nickel allergy is a chronic and recurring skin problem; females are affected more commonly than males. Nickel allergy may develop at any age. Once developed, it tends to persist life-long. Nickel is present in most of the dietary items and food is considered to be a major source of nickel exposure for the general population. Nickel content in food may vary considerably from place to place due to the difference in nickel content of the soil. However, certain foods are routinely high in nickel content. Nickel in the diet of a nickel-sensitive person can provoke dermatitis. Careful selection of food with relatively low nickel concentration can bring a reduction in the total dietary intake of nickel per day. This can influence the outcome of the disease and can benefit the nickel sensitive patient.

Nickel exposure and plasma levels of biomarkers for assessing oxidative stress in nickel electroplating workers.

Science.gov (United States)

Tsao, Yu-Chung; Gu, Po-Wen; Liu, Su-Hsun; Tzeng, I-Shiang; Chen, Jau-Yuan; Luo, Jiin-Chyuan John

2017-07-01

The mechanism of nickel-induced pathogenesis remains elusive. To examine effects of nickel exposure on plasma oxidative and anti-oxidative biomarkers. Biomarker data were collected from 154 workers with various levels of nickel exposure and from 73 controls. Correlations between nickel exposure and oxidative and anti-oxidative biomarkers were determined using linear regression models. Workers with a exposure to high nickel levels had significantly lower levels of anti-oxidants (glutathione and catalase) than those with a lower exposure to nickel; however, only glutathione showed an independent association after multivariable adjustment. Exposure to high levels of nickel may reduce serum anti-oxidative capacity.

Essential elucidation for preparation of supported nickel phosphide upon nickel phosphate precursor

International Nuclear Information System (INIS)

Liu, Xuguang; Xu, Lei; Zhang, Baoquan

2014-01-01

Preparation of supported nickel phosphide (Ni 2 P) depends on nickel phosphate precursor, generally related to its chemical composition and supports. Study of this dependence is essential and meaningful for the preparation of supported Ni 2 P with excellent catalytic activity. The chemical nature of nickel phosphate precursor is revealed by Raman and UV–vis spectra. It is found that initial P/Ni mole ratio ≥0.8 prohibits the Ni-O-Ni bridge bonding (i.e., nickel oxide). This chemical bonding will not result in Ni 2 P structure, verified by XRD characterization results. The alumina (namely, γ-Al 2 O 3 , θ-Al 2 O 3 , or α-Al 2 O 3 ) with distinct physiochemical properties also results in diverse chemical nature of nickel phosphate, and then different nickel phosphides. The influence of alumina support on producing Ni 2 P was explained by the theory of surface energy heterogeneity, calculated by the NLDFT method based on N 2 -sorption isotherm. The uniform surface energy of α-Al 2 O 3 results only in the nickel phosphosate precursor and thus the Ni 2 P phase. - Graphical abstract: Surface energy heterogeneity in alumina (namely α-Al 2 O 3 , θ-Al 2 O 3 , and γ-Al 2 O 3 ) supported multi-oxidic precursors with different reducibilities and thus diverse nickel phosphides (i.e., Ni 3 P, Ni 12 P 5 , Ni 2 P). - Highlights: • Preparing pure Ni 2 P. • Elucidating nickel phosphate precursor. • Associating with surface energy

Mechanisms of nickel toxicity in microorganisms

Science.gov (United States)

Macomber, Lee

2014-01-01

Summary Nickel has long been known to be an important human toxicant, including having the ability to form carcinomas, but until recently nickel was believed to be an issue only to microorganisms living in nickel-rich serpentine soils or areas contaminated by industrial pollution. This assumption was overturned by the discovery of a nickel defense system (RcnR/RcnA) found in microorganisms that live in a wide range of environmental niches, suggesting that nickel homeostasis is a general biological concern. To date, the mechanisms of nickel toxicity in microorganisms and higher eukaryotes are poorly understood. In this review, we summarize nickel homeostasis processes used by microorganisms and highlight in vivo and in vitro effects of exposure to elevated concentrations of nickel. On the basis of this evidence we propose four mechanisms of nickel toxicity: 1) nickel replaces the essential metal of metalloproteins, 2) nickel binds to catalytic residues of non-metalloenzymes; 3) nickel binds outside the catalytic site of an enzyme to inhibit allosterically, and 4) nickel indirectly causes oxidative stress. PMID:21799955

Leaching of Titanium and Silicon from Low-Grade Titanium Slag Using Hydrochloric Acid Leaching

Science.gov (United States)

Zhao, Longsheng; Wang, Lina; Qi, Tao; Chen, Desheng; Zhao, Hongxin; Liu, Yahui; Wang, Weijing

2018-05-01

Acid-leaching behaviors of the titanium slag obtained by selective reduction of vanadium-bearing titanomagnetite concentrates were investigated. It was found that the optimal leaching of titanium and silicon were 0.7% and 1.5%, respectively. The titanium and silicon in the titanium slag were firstly dissolved in the acidic solution to form TiO2+ and silica sol, and then rapidly reprecipitated, forming hydrochloric acid (HCl) leach residue. Most of the silicon presented in the HCl leach residue as floccules-like silica gel, while most of the titanium was distributed in the nano-sized rod-like clusters with crystallite refinement and intracrystalline defects, and, as such, 94.3% of the silicon was leached from the HCl leach residue by alkaline desilication, and 96.5% of the titanium in the titanium-rich material with some rutile structure was then digested by the concentrated sulfuric acid. This provides an alternative route for the comprehensive utilization of titanium and silicon in titanium slag.

A micromechanical constitutive model for anisotropic cyclic deformation of super-elastic NiTi shape memory alloy single crystals

Science.gov (United States)

Yu, Chao; Kang, Guozheng; Kan, Qianhua

2015-09-01

Based on the experimental observations on the anisotropic cyclic deformation of super-elastic NiTi shape memory alloy single crystals done by Gall and Maier (2002), a crystal plasticity based micromechanical constitutive model is constructed to describe such anisotropic cyclic deformation. To model the internal stress caused by the unmatched inelastic deformation between the austenite and martensite phases on the plastic deformation of austenite phase, 24 induced martensite variants are assumed to be ellipsoidal inclusions with anisotropic elasticity and embedded in the austenite matrix. The homogeneous stress fields in the austenite matrix and each induced martensite variant are obtained by using the Mori-Tanaka homogenization method. Two different inelastic mechanisms, i.e., martensite transformation and transformation-induced plasticity, and their interactions are considered in the proposed model. Following the assumption of instantaneous domain growth (Cherkaoui et al., 1998), the Helmholtz free energy of a representative volume element of a NiTi shape memory single crystal is established and the thermodynamic driving forces of the internal variables are obtained from the dissipative inequalities. The capability of the proposed model to describe the anisotropic cyclic deformation of super-elastic NiTi single crystals is first verified by comparing the predicted results with the experimental ones. It is concluded that the proposed model can capture the main quantitative features observed in the experiments. And then, the proposed model is further used to predict the uniaxial and multiaxial transformation ratchetting of a NiTi single crystal.

How to Choose between the Implant Materials Steel and Titanium in Orthopedic Trauma Surgery: Part 2 - Biological Aspects.

Science.gov (United States)

Perren, S M; Regazzoni, P; Fernandez, A A

2017-01-01

BIOLOGICAL ASPECTS OF STEEL AND TITANIUM AS IMPLANT MATERIAL IN ORTHOPEDIC TRAUMA SURGERY The following case from the ICUC database, where a titanium plate was implanted into a flourishing infection, represents the clinical experience leading to preferring titanium over steel. (Fig. 1) (6). Current opinions regarding biological aspects of implant function. The "street" opinions regarding the biological aspects of the use of steel versus titanium as a surgical trauma implant material differ widely. Statements of opinion leaders range from "I do not see any difference in the biological behavior between steel and titanium in clinical application" to "I successfully use titanium implants in infected areas in a situation where steel would act as foreign body "sustaining" infection." Furthermore, some comments imply that clinical proof for the superiority of titanium in human application is lacking. The following tries to clarify the issues addressing the different aspects more through a practical clinical approach than a purely scientific one, this includes simplifications. Today's overall biocompatibility of implant materials is acceptable but: As the vast majority of secondary surgeries are elective procedures this allows the selection of implant materials with optimal infection resistance. The different biological reactions of stainless steel and titanium are important for this segment of clinical pathologies. Biological tole - rance (18) depends on the toxicity and on the amount of soluble implant material released. Release, diffusion and washout through blood circulation determine the local concentration of the corrosion products. Alloying components of steel, especially nickel and chromium, are less than optimal in respect to tissue tolerance and allergenicity. Titanium as a pure metal provides excellent biological tolerance (3, 4, 16). Better strength was obtained by titanium alloys like TiAl6V4. The latter found limited application as surgical implants. It

Effect on growth and nickel content of cabbage plants watered with nickel solutions

Energy Technology Data Exchange (ETDEWEB)

Christensen, O B

1979-01-01

Chinese cabbage plants were watered with different concentrations of NiCl/sub 2/ solutions and the effect on growth and uptake of nickel in the plants were studied. No toxic effect on plant growth was observed. A higher content of nickel was found in the plants exposed to more concentrated nickel solutions. Nickel contamination and its clinical consequences are discussed. 29 references, 1 figure, 1 table.

Analytical Investigation of the Cyclic Behavior of Smart Recentering T-Stub Components with Superelastic SMA Bolts

Directory of Open Access Journals (Sweden)

Junwon Seo

2017-09-01

Full Text Available Partially restrained (PR bolted T-stub connections have been widely used in replacement of established fully restrained (FR welded connections, which are susceptible to sudden brittle failure. These bolted T-stub connections can permit deformation, easily exceeding the allowable limit without any fracture because they are constructed with a design philosophy whereby the plastic deformation concentrates on bolt fasteners made of ductile steel materials. Thus, the PR bolted connections take advantage of excellent energy dissipation capacity in their moment and rotation behavior. However, a considerable amount of residual deformation may occur at the bolted connection subjected to excessive plastic deformation, thereby requiring additional costs to recover the original configuration. In this study, superelastic shape memory alloy (SMA bolts, which have a recentering capability upon unloading, are fabricated so as to solve these drawbacks, and utilized by replacing conventional steel bolts in the PR bolted T-stub connection. Instead of the full-scale T-stub connection, simplified T-stub components subjected to axial force are designed on the basis of a basic equilibrium theory that transfers the bending moment from the beam to the column and can be converted into equivalent couple forces acting on the beam flange. The feasible failure modes followed by corresponding response mechanisms are taken into consideration for component design with superelastic SMA bolts. The inelastic behaviors of such T-stub components under cyclic loading are simulated by advanced three-dimensional (3D finite element (FE analysis. Finally, this study suggests an optimal design for smart recentering T-stub components with respect to recentering and energy dissipation after observing the FE analysis results.

Titanium and titanium alloys: fundamentals and applications

National Research Council Canada - National Science Library

Leyens, C; Peters, M

2003-01-01

... number of titanium alloys have paved the way for light metals to vastly expand into many industrial applications. Titanium and its alloys stand out primarily due to their high specific strength and excellent corrosion resistance, at just half the weight of steels and Ni-based superalloys. This explains their early success in the aerospace and the...

Synthesis of Titanium Oxycarbide from Titanium Slag by Methane-Containing Gas

Science.gov (United States)

Dang, Jie; Fatollahi-Fard, Farzin; Pistorius, Petrus Christiaan; Chou, Kuo-Chih

2018-02-01

In this study, reaction steps of a process for synthesis of titanium oxycarbide from titanium slag were demonstrated. This process involves the reduction of titanium slag by a methane-hydrogen-argon mixture at 1473 K (1200 °C) and the leaching of the reduced products by hydrofluoric acid near room temperature to remove the main impurity (Fe3Si). Some iron was formed by disproportionation of the main M3O5 phase before gaseous reduction started. Upon reduction, more iron formed first, followed by reduction of titanium dioxide to suboxides and eventually oxycarbide.

Separation and Precipitation of Nickel from Acidic Sulfate Leaching Solution of Molybdenum-Nickel Black Shale by Potassium Nickel Sulfate Hexahydrate Crystallization

Science.gov (United States)

Deng, Zhigan; Wei, Chang; Fan, Gang; Li, Xingbin; Li, Minting; Li, Cunxiong

2018-02-01

Nickel was separated and precipitated with potassium nickel sulfate hexahydrate [K2Ni(SO4)2·6H2O] from acidic sulfate solution, a leach solution from molybdenum-nickel black shale. The effects of the potassium sulfate (K2SO4) concentration, crystallization temperature, solution pH, and crystallization time on nickel(II) recovery and iron(III) precipitation were investigated, revealing that nickel and iron were separated effectively. The optimum parameters were K2SO4 concentration of 200 g/L, crystallization temperature of 10°C, solution pH of 0.5, and crystallization time of 24 h. Under these conditions, 97.6% nickel(II) was recovered as K2Ni(SO4)2·6H2O crystals while only 2.0% of the total iron(III) was precipitated. After recrystallization, 98.4% pure K2Ni(SO4)2·6H2O crystals were obtained in the solids. The mother liquor was purified by hydrolysis-precipitation followed by cooling, and more than 99.0% K2SO4 could be crystallized. A process flowsheet was developed to separate iron(III) and nickel(II) from acidic-sulfate solution.

Multiscale electrochemical analysis of the corrosion of titanium and nitinol for implant applications

International Nuclear Information System (INIS)

Izquierdo, J.; González-Marrero, M.B.; Bozorg, M.; Fernández-Pérez, B.M.; Vasconcelos, H.C.; Santana, J.J.; Souto, R.M.

2016-01-01

Highlights: • Direct screening of differences in the surface reactivity of the passive layers formed on pure titanium and nitinol. • Distinct effect of polarization on the passive layers. • Detection of nickel soluble species released from corrosion pits. - Abstract: Surface electrochemical activity of titanium and nitinol biomaterials in naturally aerated Ringer’s physiological solution was investigated using potentiodynamic polarization and scanning electrochemical microscopy (SECM) techniques. SECM was operated in feedback and redox competition modes as a function of potential applied to the substrate. The kinetics of the electron transfer rate on both materials was characterized by mathematical modelling of the Z-approach curves monitored under feedback conditions. The rate constant values greatly depended on the characteristics of the passive layers formed over the metals under potentiostatic control. A more insulating film was found on nitinol when biased at low polarizations, resulting in smaller tip current increments during tip approach to the investigated surface under positive feedback and competition operation modes. However, at higher anodic polarizations, nitinol passive layers experience breakdown, and therefore tip current values reflect the release of metal cations from the biomaterial surface.

Titanium by design: TRIP titanium alloy

Science.gov (United States)

Tran, Jamie

Motivated by the prospect of lower cost Ti production processes, new directions in Ti alloy design were explored for naval and automotive applications. Building on the experience of the Steel Research Group at Northwestern University, an analogous design process was taken with titanium. As a new project, essential kinetic databases and models were developed for the design process and used to create a prototype design. Diffusion kinetic models were developed to predict the change in phase compositions and microstructure during heat treatment. Combining a mobility database created in this research with a licensed thermodynamic database, ThermoCalc and DICTRA software was used to model kinetic compositional changes in titanium alloys. Experimental diffusion couples were created and compared to DICTRA simulations to refine mobility parameters in the titanium mobility database. The software and database were able to predict homogenization times and the beta→alpha plate thickening kinetics during cooling in the near-alpha Ti5111 alloy. The results of these models were compared to LEAP microanalysis and found to be in reasonable agreement. Powder metallurgy was explored using SPS at GM R&D to reduce the cost of titanium alloys. Fully dense Ti5111 alloys were produced and achieved similar microstructures to wrought Ti5111. High levels of oxygen in these alloys increased the strength while reducing the ductility. Preliminary Ti5111+Y alloys were created, where yttrium additions successfully gettered excess oxygen to create oxides. However, undesirable large oxides formed, indicating more research is needed into the homogeneous distribution of the yttrium powder to create finer oxides. Principles established in steels were used to optimize the beta phase transformation stability for martensite transformation toughening in titanium alloys. The Olson-Cohen kinetic model is calibrated to shear strains in titanium. A frictional work database is established for common alloying

Environmental and human toxicology of nickel - a review; Umwelt- und Humantoxikologie von Nickel - eine aktuelle Uebersicht

Energy Technology Data Exchange (ETDEWEB)

Beyersmann, D. [Fachbereich Biologie und Chemie, Univ. Bremen (Germany)

2006-07-01

Nickel is a relatively rare element, and its concentrations in ambient air, soils and waters are very low. Higher burdens of nickel are found in nickel industries and their proximity. The human uptake of nickel from the ambient air is neglectably low, except in industrial exposures. The main fraction of human nickel uptake is from food, nearly 50% stems from vegetables. Only about 2% of the oral uptake of nickel are resorbed and distributed over all organs investigated. The uptake of nickel compounds through the skin generally is very low. However, chronic skin contact with nickel and nickel compounds causes a specific contact allergy. This disease was observed after occupational exposure but also frequently in the general population. The number of new cases has dropped considerably due to reinforced prevention. Epidemiological studies with workers of nickel smelting and refining plants have demonstrated increased risks of nose and lung cancer. Human data are supported by results from animal experiments which have shown that inhalation of various nickel compounds caused lung cancer. Furthermore, animal experiments have yielded evidence that oral and inhalative exposure to nickel compounds impair reproduction. National and international agencies have classified various nickel compounds as carcinogenic to humans. The unit cancer risk attributed to life-long inhalation of 1 {mu}g Ni/m{sup 3} air is estimated to be between 2 x 10{sup -4} and 7 x 10{sup -4}. Occupational exposure limits in Germany have been the Technical Guidance Values of 0.5 mg/m{sup 3} for nickel and weakly soluble nickel compounds and of 0.05 mg/m{sup 3} for inhalable droplets of soluble nickel salts. The German limit value for ambient immission is 0.015 mg Ni/m{sup 2}. d, and for emission 0,5 mg Ni/m{sup 3}. Limit values for nickel in air are to be taken not as safe thresholds but as guidance values for the delimitation of the cancer risk. (orig.)

Progress in the Development of Lightweight Nickel Electrode for Nickel-Hydrogen Cell

Science.gov (United States)

Britton, Doris L.

1999-01-01

Development of a high specific energy battery is one of the objectives of the lightweight nickel-hydrogen (Ni-H2) program at the NASA Glenn Research Center. The approach has been to improve the nickel electrode by continuing combined in-house and contract efforts to develop a lighter weight electrode for the nickel-hydrogen cell. Small fiber diameter nickel plaques are used as conductive supports for the nickel hydroxide active material. These plaques are commercial products and have an advantage of increased surface area available for the deposition of active material. Initial tests include activation and capacity measurements at five different discharge levels, C/2, 1.0 C, 1.37 C, 2.0 C, and 2.74 C. The electrodes are life cycle tested using a half-cell configuration at 40 and 80% depths-of-discharge (DOD) in a low-Earth-orbit regime. The electrodes that pass the initial tests are life cycle-tested in a boiler plate nickel-hydrogen cell before flight weight design are built and tested.

Atomic layer deposition of titanium oxide films on As-synthesized magnetic Ni particles: Magnetic and safety properties

International Nuclear Information System (INIS)

Uudeküll, Peep; Kozlova, Jekaterina; Mändar, Hugo; Link, Joosep; Sihtmäe, Mariliis; Käosaar, Sandra; Blinova, Irina; Kasemets, Kaja; Kahru, Anne; Stern, Raivo; Tätte, Tanel; Kukli, Kaupo; Tamm, Aile

2017-01-01

Spherical nickel particles with size in the range of 100–400 nm were synthesized by non-aqueous liquid phase benzyl alcohol method. Being developed for magnetically guided biomedical applications, the particles were coated by conformal and antimicrobial thin titanium oxide films by atomic layer deposition. The particles retained their size and crystal structure after the deposition of oxide films. The sensitivity of the coated particles to external magnetic fields was increased compared to that of the uncoated powder. Preliminary toxicological investigations on microbial cells and small aquatic crustaceans revealed non-toxic nature of the synthesized particles.

Atomic layer deposition of titanium oxide films on As-synthesized magnetic Ni particles: Magnetic and safety properties

Energy Technology Data Exchange (ETDEWEB)

Uudeküll, Peep, E-mail: peep.uudekull@ut.ee [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia); Kozlova, Jekaterina; Mändar, Hugo [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia); Link, Joosep [Laboratory of Chemical Physics, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Sihtmäe, Mariliis [Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Käosaar, Sandra [Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Faculty of Chemical and Materials Technology, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Blinova, Irina; Kasemets, Kaja; Kahru, Anne [Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Stern, Raivo [Laboratory of Chemical Physics, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Tätte, Tanel [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia); Kukli, Kaupo [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia); University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland); Tamm, Aile [Institute of Physics, University of Tartu, W. Ostwaldi Str.1, 50411 Tartu (Estonia)

2017-05-01

Spherical nickel particles with size in the range of 100–400 nm were synthesized by non-aqueous liquid phase benzyl alcohol method. Being developed for magnetically guided biomedical applications, the particles were coated by conformal and antimicrobial thin titanium oxide films by atomic layer deposition. The particles retained their size and crystal structure after the deposition of oxide films. The sensitivity of the coated particles to external magnetic fields was increased compared to that of the uncoated powder. Preliminary toxicological investigations on microbial cells and small aquatic crustaceans revealed non-toxic nature of the synthesized particles.

Absorption and retention of nickel from drinking water in relation to food intake and nickel sensitivity.

Science.gov (United States)

Nielsen, G D; Søderberg, U; Jørgensen, P J; Templeton, D M; Rasmussen, S N; Andersen, K E; Grandjean, P

1999-01-01

Two studies were performed to examine the influence of fasting and food intake on the absorption and retention of nickel added to drinking water and to determine if nickel sensitization played any role in this regard. First, eight nonallergic male volunteers fasted overnight before being given nickel in drinking water (12 micrograms Ni/kg) and, at different time intervals, standardized 1400-kJ portions of scrambled eggs. When nickel was ingested in water 30 min or 1 h prior to the meal, peak nickel concentrations in serum occurred 1 h after the water intake, and the peak was 13-fold higher than the one seen 1 h after simultaneous intake of nickel-containing water and scrambled eggs. In the latter case, a smaller, delayed peak occurred 3 h after the meal. Median urinary nickel excretion half-times varied between 19.9 and 26.7 h. Within 3 days, the amount of nickel excreted corresponded to 2.5% of the nickel ingested when it was mixed into the scrambled eggs. Increasing amounts were excreted as the interval between the water and the meal increased, with 25.8% of the administered dose being excreted when the eggs were served 4 h prior to the nickel-containing drinking water. In the second experiment, a stable nickel isotope, 61Ni, was given in drinking water to 20 nickel-sensitized women and 20 age-matched controls, both groups having vesicular hand eczema of the pompholyx type. Nine of 20 nickel allergic eczema patients experienced aggravation of hand eczema after nickel administration, and three also developed a maculopapular exanthema. No exacerbation was seen in the control group. The course of nickel absorption and excretion in the allergic groups did not differ and was similar to the pattern seen in the first study, although the absorption in the women was less. A sex-related difference in gastric emptying rates may play a role. Thus, food intake and gastric emptying are of substantial significance for the bioavailability of nickel from aqueous solutions

A cost-minimization analysis of root canal treatment before and after education in nickel-titanium rotary technique in general practice.

Science.gov (United States)

Koch, M; Tegelberg, A; Eckerlund, I; Axelsson, S

2012-07-01

To compare root canal treatments performed before and after education in a nickel-titanium rotary technique (NiTiR) with respect to costs for instrumentation and number of instrumentation sessions in a County Public Dental Service in Sweden.   Following education, 77% of the general dental practitioners adopted completely the NiTiR. The randomly selected sample comprised 850 root canal treatments: 425 performed after the education, mainly using the NiTiR-technique (group A) and 425 performed before, using mainly stainless steel hand instrumentation (SSI) (group B). The number of instrumentation sessions in root canal treatments in group A and B was calculated. A CMA was undertaken on the assumption that treatment outcome was identical in group A and B. Direct costs associated with SSI and NiTiR were estimated and compared. Investment costs required for implementation of NiTiR were calculated, but not included in the CMA. Instrumentation sessions were counted in 418 (98%) root canal treatments performed in group A and 419 (99%) in group B. The number of instrumentation sessions in group A was significantly lower; 2.38, compared with 2.82 in group B (P session was saved. Root canal treatments in teeth with one canal, and three or more canals, were completed in significantly fewer instrumentation sessions after the education (P sessions were SEK 2587 (USD 411) for group A and SEK 2851 (USD 453) for group B, for teeth with one canal, and SEK 2946 (USD 468) for group A and SEK 3510 (USD 558) for group B, for teeth with three or more canals (year 2011). Root canal treatments of teeth with two canals showed no significant difference with respect to number of instrumentation sessions and costs. Significantly fewer instrumentation sessions were required in group A, and root canal instrumentation therefore costs less than in group B. On the assumption that treatment outcome is identical in group A and B, root canal instrumentation performed after the education was more

The influence of simulated clinical use on the flexibility of rotary ProTaper Universal, K3 and EndoSequence nickel-titanium instruments.

Science.gov (United States)

Viana, A C D; Pereira, E S J; Bahia, M G A; Buono, V T L

2013-09-01

To investigate the influence of cyclic flexural and torsional loading on the flexibility of ProTaper Universal, K3 and EndoSequence nickel-titanium instruments, in view of the hypothesis that these types of loading would decrease the flexibility of the selected NiTi rotary files. The instruments evaluated were S2 and F1 ProTaper Universal, sizes 20 and 25, .06 taper K3, and sizes 20 and 25, .06 taper EndoSequence. Flexibility was determined by 45° bending tests according to ISO 3630-1 specification. Values of the bending moment (MB ) obtained with new instruments were considered as the control group (CG). Bending tests were then conducted in instruments previously fatigued to one-fourth and three-fourths of their average fatigue life (fatigue groups, FG¼ and FG¾), as well as after cyclic torsional loading (torsional group, TG). Fatigue tests were carried out in a bench device that allowed the files to rotate freely inside an artificial canal with an angle of curvature of 45° and a radius of 5 mm. Cyclic torsional loading tests were performed that entailed rotating the instrument from zero angular deflection to 180° and then returning to zero applied torque in 20 cycles. Data were analysed using one-way analysis of variance at a significance level of 5%. Simulated clinical use by means of flexural fatigue tests did not affect the flexibility of the instruments, except for a significant increase in flexibility observed in a few instruments (P instruments and after cyclic torsional loading showed no significant differences between them (P > 0.05). The flexibility of rotary ProTaper Universal, K3 and EndoSequence NiTi instruments, measured in bending tests, was not adversely affected by simulated clinical use in curved root canals. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Chitosan patterning on titanium alloys

OpenAIRE

Gilabert Chirivella, Eduardo; Pérez Feito, Ricardo; Ribeiro, Clarisse; Ribeiro, Sylvie; Correia, Daniela; González Martin, María Luisa; Manero Planella, José María; Lanceros Méndez, Senentxu; Gallego Ferrer, Gloria; Gómez Ribelles, José Luis

2017-01-01

Titanium and its alloys are widely used in medical implants because of their excellent properties. However, bacterial infection is a frequent cause of titanium-based implant failure and also compromises its osseointegration. In this study, we report a new simple method of providing titanium surfaces with antibacterial properties by alternating antibacterial chitosan domains with titanium domains in the micrometric scale. Surface microgrooves were etched on pure titanium disks at i...

Forces released during alignment with a preadjusted appliance with different types of elastomeric ligatures.

Science.gov (United States)

Franchi, Lorenzo; Baccetti, Tiziano

2006-05-01

The purpose of this in-vitro study was to compare the forces generated by new nonconventional elastomeric ligatures (NCEL) and conventional elastomeric ligatures (CEL) during leveling and aligning phases. The testing model consisted of 5 stainless steel 0.022-in preadjusted brackets for second premolar, first premolar, canine, lateral incisor, and central incisor. The canine bracket was welded to a sliding bar that allowed for different vertical positions. The forces generated by 3 sizes of wires (0.012-, 0.014-, and 0.016-in superelastic nickel-titanium) with the 2 types of elastomeric ligatures at different amounts of upward canine misalignment (1.5, 3, 4.5, and 6 mm) were recorded. Significant differences between CEL and NCEL were found for all tested variables (P <.01) with the exception of the 0.014- and 0.016-in wires at canine misalignment of 1.5 mm. A noticeable amount of force was generated with the NCEL at all 4 canine positions with all 3 wire sizes (from about 50 to about 150 g). With 4.5 mm of canine misalignment or more, the average amount of released force with the CEL was approximately zero.

On the use of titanium hydride for powder injection moulding of titanium-based alloys

International Nuclear Information System (INIS)

Carrenoo-Morelli, E.; Bidaux, J.-E.

2009-01-01

Full text: Titanium and titanium-based alloys are excellent materials for a number of engineering applications because of their high strength, lightweight, good corrosion resistance, non magnetic characteristic and biocompatibility. The current processing steps are usually costly, and there is a growing demand for net-shape solutions for manufacturing parts of increasing complexity. Powder injection moulding is becoming a competitive alternative, thanks to the advances in production of good quality base-powders, binders and sintering facilities. Titanium hydride powders, have the attractiveness of being less reactive than fine titanium powders, easier to handle, and cheaper. This paper summarizes recent advances on PIM of titanium and titanium alloys from TiH2 powders, including shape-memory NiTi alloys. (author)

Dynamic mechanical properties of straight titanium alloy arch wires.

Science.gov (United States)

Kusy, R P; Wilson, T W

1990-10-01

Eight straight-wire materials were studied: an orthodontic titanium-molybdenum (Ti-Mo) product, TMA; three orthodontic nickel-titanium (Ni-Ti) products, Nitinol, Titanal, and Orthonol; three prototype alloys, a martensitic, an austenitic, and a biphasic alloy; and a hybrid shape-memory-effect product, Biometal. Each wire was prepared with a length-to-cross-sectional area of at least 3600 cm-1. With an Autovibron Model DDV-II-C used in the tensile mode, each sample was scanned from -120 to +200 degrees C at 2 degrees C/min. From the data base, plots of the log storage modulus, log tan delta, and percent change in length vs. temperature were generated. Results showed that the dynamic mechanical properties of the alloys within this TI system are quite different. The Ti-Mo alloy, TMA, was invariant with temperature, having a modulus of 7.30 x 10(11) dyne/cm2 (10.6 x 10(6) psi). The three cold-worked alloys--Nitinol, Titanal, and Orthonol--appeared to be similar, having a modulus of 5.74 x 10(11) dyne/cm2 (8.32 x 10(6) psi). The biphasic shape-memory alloy displayed a phase transformation near ambient temperature; whereas the hybrid shape-memory product, Biometal, underwent a 3-5% change in length during its transformation between 95 and 125 degrees C. Among the Ni-Ti wires tested, several different types of alloys were represented by this intermetallic material.

Resilient and Corrosion-Proof Rolling Element Bearings Made from Superelastic Ni-Ti Alloys for Aerospace

Science.gov (United States)

Dellacorte, Christopher

2014-01-01

Mechanical components (bearings, gears, mechanisms) typically utilize hardened construction materials to minimize wear and attain long life. In such components, loaded contact points (e.g., meshing gear teeth, bearing balls-raceway contacts) experience high contact stresses. The combination of high hardness and high elastic modulus often leads to damaging contact stress and denting, particularly during transient overload events such as shock impacts that occur during the launching of space vehicles or the landing of aircraft. In this webinar, Dr. DellaCorte will introduce the results of a research project that employs a superelastic alloy, Ni-Ti for rolling element bearing applications. Bearings and components made from such alloys can alleviate many problems encountered in advanced aerospace applications and may solve many terrestrial applications as well

The cost of nickel allergy

DEFF Research Database (Denmark)

Hamann, Carsten R; Hamann, Dathan; Hamann, Curtis

2013-01-01

%), followed by aluminium-bronze (62, 17%). In total, 239 denominations released nickel (28%). Coins from Bolivia, Brazil and Costa Rica did not release nickel. Fewer than one-third of the denominations or issues from China, India, the euro area and Indonesia released nickel. In the United States, the Russian...... Federation, Japan, and Mexico, one-third or more of the denominations released nickel. Conclusions. This worldwide selection of circulating coins covered countries with 75% of the world population, and shows that the majority of the world population lives in countries where coins release nickel. Pertinently...

Biosorption of nickel with barley straw.

Science.gov (United States)

Thevannan, Ayyasamy; Mungroo, Rubeena; Niu, Catherine Hui

2010-03-01

Wastewater containing nickel sulphate generated from a nickel plating industry is of great concern. In the present work, biosorption of nickel by barley straw from nickel sulphate solution was investigated. Nickel uptake at room temperature (23+/-0.5 degrees C) was very sensitive to solution pH, showing a better uptake value at a pH of 4.85+/-0.10 among the tested values. The nickel biosorption isotherm fitted well the Langmuir equation. When the ionic strength (IS) of the solution was increased from less than 0.02-0.6M, nickel uptake was reduced to 12% of that obtained at IS of less than 0.02 M. Barley straw showed a higher nickel uptake (0.61 mmol/g) than acid washed crab shells (0.04 mmol/g), demonstrating its potential as an adsorbent for removal of nickel. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

A Model for Creep and Creep Damage in the γ-Titanium Aluminide Ti-45Al-2Mn-2Nb.

Science.gov (United States)

Harrison, William; Abdallah, Zakaria; Whittaker, Mark

2014-03-14

Gamma titanium aluminides (γ-TiAl) display significantly improved high temperature mechanical properties over conventional titanium alloys. Due to their low densities, these alloys are increasingly becoming strong candidates to replace nickel-base superalloys in future gas turbine aeroengine components. To determine the safe operating life of such components, a good understanding of their creep properties is essential. Of particular importance to gas turbine component design is the ability to accurately predict the rate of accumulation of creep strain to ensure that excessive deformation does not occur during the component's service life and to quantify the effects of creep on fatigue life. The theta (θ) projection technique is an illustrative example of a creep curve method which has, in this paper, been utilised to accurately represent the creep behaviour of the γ-TiAl alloy Ti -45Al-2Mn-2Nb. Furthermore, a continuum damage approach based on the θ-projection method has also been used to represent tertiary creep damage and accurately predict creep rupture.

Nickel accumulation by Hybanthus floribundus

Energy Technology Data Exchange (ETDEWEB)

Severne, B C

1974-04-26

Several ecotypes of Hybanthus floribundus are found across the southern part of Australia. However, the three nickel accumulating ecotypes are restricted to a broad belt in Western Australia. Nickel concentrations in this shrub were observed to decrease southwards (from 8000 to 1000 p.p.m.) as the annual rainfall increased from 7 inches to more than 30 inches. Studies have shown that nickel concentrations increase from the roots through the rootstock, into the stems and reach maximum towards the leaf tips. High nickel concentrations are also seen in seed capsules (1500 p.p.m.), seeds (2000 p.p.m.) and flowers. The maximum nickel concentration recorded is 1.6% (26% nickel in ash) in mature leaf tissue. 16 references, 2 tables.

Classification of titanium dioxide

International Nuclear Information System (INIS)

Macias B, L.R.; Garcia C, R.M.; Maya M, M.E.; Ita T, A. De; Palacios G, J.

2002-01-01

In this work the X-ray diffraction (XRD), Scanning Electron Microscopy (Sem) and the X-ray Dispersive Energy Spectroscopy techniques are used with the purpose to achieve a complete identification of phases and mixture of phases of a crystalline material as titanium dioxide. The problem for solving consists of being able to distinguish a sample of titanium dioxide being different than a titanium dioxide pigment. A standard sample of titanium dioxide with NIST certificate is used, which indicates a purity of 99.74% for the TiO 2 . The following way is recommended to proceed: a)To make an analysis by means of X-ray diffraction technique to the sample of titanium dioxide pigment and on the standard of titanium dioxide waiting not find differences. b) To make a chemical analysis by the X-ray Dispersive Energy Spectroscopy via in a microscope, taking advantage of the high vacuum since it is oxygen which is analysed and if it is concluded that the aluminium oxide appears in a greater proportion to 1% it is established that is a titanium dioxide pigment, but if it is lesser then it will be only titanium dioxide. This type of analysis is an application of the nuclear techniques useful for the tariff classification of merchandise which is considered as of difficult recognition. (Author)

STRETCHY ELECTRONICS. Hierarchically buckled sheath-core fibers for superelastic electronics, sensors, and muscles.

Science.gov (United States)

Liu, Z F; Fang, S; Moura, F A; Ding, J N; Jiang, N; Di, J; Zhang, M; Lepró, X; Galvão, D S; Haines, C S; Yuan, N Y; Yin, S G; Lee, D W; Wang, R; Wang, H Y; Lv, W; Dong, C; Zhang, R C; Chen, M J; Yin, Q; Chong, Y T; Zhang, R; Wang, X; Lima, M D; Ovalle-Robles, R; Qian, D; Lu, H; Baughman, R H

2015-07-24

Superelastic conducting fibers with improved properties and functionalities are needed for diverse applications. Here we report the fabrication of highly stretchable (up to 1320%) sheath-core conducting fibers created by wrapping carbon nanotube sheets oriented in the fiber direction on stretched rubber fiber cores. The resulting structure exhibited distinct short- and long-period sheath buckling that occurred reversibly out of phase in the axial and belt directions, enabling a resistance change of less than 5% for a 1000% stretch. By including other rubber and carbon nanotube sheath layers, we demonstrated strain sensors generating an 860% capacitance change and electrically powered torsional muscles operating reversibly by a coupled tension-to-torsion actuation mechanism. Using theory, we quantitatively explain the complementary effects of an increase in muscle length and a large positive Poisson's ratio on torsional actuation and electronic properties. Copyright © 2015, American Association for the Advancement of Science.

Corrosion properties of plasma deposited nickel and nickel-based alloys

Czech Academy of Sciences Publication Activity Database

Voleník, Karel; Pražák, M.; Kalabisová, E.; Kreislová, K.; Had, J.; Neufuss, Karel

2003-01-01

Roč. 48, č. 3 (2003), s. 215-226 ISSN 0001-7043 R&D Projects: GA ČR GA106/99/0298 Institutional research plan: CEZ:AV0Z2043910 Keywords : plasma deposits, nickel, nickel-based alloys Subject RIV: JK - Corrosion ; Surface Treatment of Materials

EPIDEMIOLOGICAL AND PATHOGENETIC ASPECTS OF NICKEL POISONING

Directory of Open Access Journals (Sweden)

Vladmila Bojanic

2007-04-01

Full Text Available Nickel is widely distributed in the environment. High consumption of nickel containing products inevitably leads to environmental pollution by nickel and its derivatives at all stages of production, utilization, and disposal.Human exposure to nickel occurs primarily via inhalation and ingestion and is particularly high among nickel metallurgy workers. In addition, implantation of nickel-containing endoprostheses and iatrogenic administration of nickel-contaminated medica-tions leads to significant parenteral exposures. Exposure to nickel compounds can produce a variety of adverse effects on human health. Nickel allergy in the form of contact dermatitis is the most common reaction.A frontal headache, vertigo, nausea, vomiting, insomnia, and irritability are the most common signs of acute poisoning with nickel compounds. The respiratory tract, kidneys and liver suffer the most significant changes like nickel pneumoconiosis, chronic rhinitis and sinonasal tumors and transitory nephropathy. Although the accumulation of nickel in the body through chronic exposure can lead to lung fibrosis, cardiovascular and kidney diseases, the most serious concerns relate to nickel’s carcinogenic activity. Nickel compounds are carcinogenic to humans and metallic nickel is possibly carcinogenic to humans.

Corrosion behaviour and galvanic coupling of titanium and welded titanium in LiBr solutions

International Nuclear Information System (INIS)

Blasco-Tamarit, E.; Igual-Munoz, A.; Garcia Anton, J.; Garcia-Garcia, D.

2007-01-01

Corrosion resistance and galvanic coupling of Grade 2 commercially pure titanium in its welded and non-welded condition were systematically analyzed in LiBr solutions. Galvanic corrosion was evaluated through two different methods: anodic polarization (according to the Mixed Potential Theory) and electrochemical noise (using a zero-resistance ammeter). Samples have been etched to study the microstructure. The action of lithium chromate as corrosion inhibitor has been evaluated. Titanium and welded titanium showed extremely low corrosion current densities and elevated pitting potential values (higher than 1 V). The results of both methods, anodic polarization and electrochemical noise, showed that the welded titanium was always the anodic element of the pair titanium-welded titanium, so that its corrosion resistance decreases due to the galvanic effect

Positron annihilation in hydrogenated and electron-irradiated titanium alloys

International Nuclear Information System (INIS)

Mukashev, K.M.; Zaikin, Yu.A.

2002-01-01

that material properties were not completely recovered, probably due to residual point defects of radiation origin. It is obvious that the temperature of 600 deg. C was not sufficient for hydrogen extraction from titanium. These results are confirmed by data of previous studies where niobium and nickel hydrogenated after electron irradiation were studied. These data show that the shift in the recovery start exceeded 130 deg. C. Thus, interaction of vacancy-type defects with previously introduced hydrogen surrounding causes alterations in the efficient size of positron localization centers and shifts the first recovery stage to the region of higher temperature values. Generally, the results of this study demonstrate a significant role of hydrogen in alterations of the electron structure of damaged materials. They show the increasing hydrogen interaction with materials in presence of structural imperfections of deformational and radiation origin. Both hydrogen behavior in irradiated titanium alloys and the observed alterations in positron annihilation characteristics cannot be described in frames of a simple model based on the concept of proton interaction with a vacancy. Variety of radiation defects, such as complexes of point defects, dislocations, cracks, etc., should be taken into account. Application of positron annihilation methods provides important information on hydrogen interaction with lattice imperfections that can be a useful approach to the problem of hydrogen embrittlement of structural materials in the fields of ionizing radiation

Nickel: makes stainless steel strong

Science.gov (United States)

Boland, Maeve A.

2012-01-01

Nickel is a silvery-white metal that is used mainly to make stainless steel and other alloys stronger and better able to withstand extreme temperatures and corrosive environments. Nickel was first identified as a unique element in 1751 by Baron Axel Fredrik Cronstedt, a Swedish mineralogist and chemist. He originally called the element kupfernickel because it was found in rock that looked like copper (kupfer) ore and because miners thought that "bad spirits" (nickel) in the rock were making it difficult for them to extract copper from it. Approximately 80 percent of the primary (not recycled) nickel consumed in the United States in 2011 was used in alloys, such as stainless steel and superalloys. Because nickel increases an alloy's resistance to corrosion and its ability to withstand extreme temperatures, equipment and parts made of nickel-bearing alloys are often used in harsh environments, such as those in chemical plants, petroleum refineries, jet engines, power generation facilities, and offshore installations. Medical equipment, cookware, and cutlery are often made of stainless steel because it is easy to clean and sterilize. All U.S. circulating coins except the penny are made of alloys that contain nickel. Nickel alloys are increasingly being used in making rechargeable batteries for portable computers, power tools, and hybrid and electric vehicles. Nickel is also plated onto such items as bathroom fixtures to reduce corrosion and provide an attractive finish.

EPIDEMIOLOGICAL AND PATHOGENETIC ASPECTS OF NICKEL POISONING

OpenAIRE

Vladmila Bojanic; Vladimir Ilic; Biljana Jovic

2007-01-01

Nickel is widely distributed in the environment. High consumption of nickel containing products inevitably leads to environmental pollution by nickel and its derivatives at all stages of production, utilization, and disposal.Human exposure to nickel occurs primarily via inhalation and ingestion and is particularly high among nickel metallurgy workers. In addition, implantation of nickel-containing endoprostheses and iatrogenic administration of nickel-contaminated medica-tions leads to signif...

Relationship between nickel allergy and diet

OpenAIRE

Sharma Ashimav

2007-01-01

Nickel is a ubiquitous trace element and it occurs in soil, water, air and of the biosphere. It is mostly used to manufacture stainless steel. Nickel is the commonest cause of metal allergy. Nickel allergy is a chronic and recurring skin problem; females are affected more commonly than males. Nickel allergy may develop at any age. Once developed, it tends to persist life-long. Nickel is present in most of the dietary items and food is considered to be a major source of nickel exposure for the...

Characterization and Growth Mechanism of Nickel Nanowires Resulting from Reduction of Nickel Formate in Polyol Medium

Directory of Open Access Journals (Sweden)

Olga A. Logutenko

2016-01-01

Full Text Available Nickel linear nanostructures were synthesized by reduction of nickel formate with hydrazine hydrate in ethylene glycol medium in the absence of any surfactants or capping agents for direction of the particles growth. The effect of the synthesis conditions such as temperature, reduction time, type of polyol, and nickel formate concentration on the reduction products was studied. The size and morphology of the nickel nanowires were characterized by X-ray diffraction, scanning, and transmission electron microscopy. It was shown that the nickel nanocrystallites were wire-shaped with a face-center-cubic phase. Ethylene glycol was found to play a crucial role in the formation of the nickel nanowires. The possible growth processes of the wire-shaped particles taking place at 110 and 130°C are discussed. It was shown that, under certain synthesis conditions, nickel nanowires grow on the surface of the crystals of the solid intermediate of nickel with hydrazine hydrate.

Absorption and retention of nickel from drinking water in relation to food intake and nickel sensitivity

DEFF Research Database (Denmark)

Nielsen, G D; Søderberg, U; Jørgensen, Poul Jørgen

1999-01-01

nickel in drinking water (12 micrograms Ni/kg) and, at different time intervals, standardized 1400-kJ portions of scrambled eggs. When nickel was ingested in water 30 min or 1 h prior to the meal, peak nickel concentrations in serum occurred 1 h after the water intake, and the peak was 13-fold higher...... than the one seen 1 h after simultaneous intake of nickel-containing water and scrambled eggs. In the latter case, a smaller, delayed peak occurred 3 h after the meal. Median urinary nickel excretion half-times varied between 19.9 and 26.7 h. Within 3 days, the amount of nickel excreted corresponded...... to 2.5% of the nickel ingested when it was mixed into the scrambled eggs. Increasing amounts were excreted as the interval between the water and the meal increased, with 25.8% of the administered dose being excreted when the eggs were served 4 h prior to the nickel-containing drinking water...

Electrowinning molten titanium from titanium dioxide

CSIR Research Space (South Africa)

Van Vuuren, DS

2005-10-01

Full Text Available the Manufacturing and Materials Industry in it quest for global competitiveness CSIR Manufacturing and Materials Technology 3 Rationale – Titanium Cost Build-up Material Cost Ilmenite $0.27/kg Ti sponge Titanium slag $0.75/kg Ti Sponge TiCl4 and TiO2 $3....10/kg Ti Sponge Ti Sponge raw materials costs $5.50/kg Ti Sponge Total Ti Sponge cost $9-$11/kg Ti Sponge Ti ingot $15-17/kg Ti Aluminium $1.7/kg Al Supporting the Manufacturing and Materials Industry in its quest for global competitivenessorting...

Self-Lubricating Coatings for Elevated Temperature Applications Using A High-Velocity-Particle-Consolidation (HVPC) Process

Science.gov (United States)

2008-12-01

candidate materials like nickel based super-alloys and ferritic and martensitic stainless steels [7]. However, Ti alloys have rather poor surface...However, cold spray is usually limited to ductile materials like aluminum, nickel, stainless steel , copper, and titanium alloys [67-74]. Hard and brittle...process include iron, stainless steel , nickel, copper, aluminum, molybdenum, titanium, and many alloys [104]. 2.2.4 Bonding in Cold Spray The actual

Bioavailability of nickel in man: effects of foods and chemically-defined dietary constituents on the absorption of inorganic nickel.

Science.gov (United States)

Solomons, N W; Viteri, F; Shuler, T R; Nielsen, F H

1982-01-01

By serial determination of the change in plasma nickel concentration following a standard dose of 22.4 mg of nickel sulfate hexahydrate containing 5 mg of elemental nickel, the bioavailability of nickel was estimated in human subjects. Plasma nickel concentration was stable in the fasting state and after an unlabeled test meal, but after the standard dose of nickel in water was elevated 48.8, 73.0, 80.0, and 53.3 microgram/1, respectively, at hours 1, 2, 3, and 4. Plasma nickel did not rise above fasting levels when 5 mg of nickel was added to two standard meals: a typical Guatemalan meal and a North American breakfast. When 5 mg of nickel was added to five beverages-whole cow milk, coffee, tea, orange juice, and Coca Cola-the rise in plasma nickel was significantly suppressed with all but Coca Cola. Response to nickel also was suppressed in the presence of 1 g of ascorbic acid. Phytic acid in a 2:1 molar ratio with nickel, however, did not affect the rise in plasma nickel. The chelate of iron and ethylenediaminetetraacetate, NaFeEDTA, an iron-fortifying agent suggested for application in Central America, slightly but not significantly depressed plasma nickel rise at 2 hours, whereas disodium EDTA depressed plasma nickel levels significantly below the fasting nickel curve at 3 and 4 hours postdose. These studies suggest that the differential responses of inorganic nickel to distinct foods, beverages, and chemically-defined dietary constituents could be important to human nutrition.

Plasmonic Titanium Nitride Nanostructures via Nitridation of Nanopatterned Titanium Dioxide

DEFF Research Database (Denmark)

Guler, Urcan; Zemlyanov, Dmitry; Kim, Jongbum

2017-01-01

Plasmonic titanium nitride nanostructures are obtained via nitridation of titanium dioxide. Nanoparticles acquired a cubic shape with sharper edges following the rock-salt crystalline structure of TiN. Lattice constant of the resulting TiN nanoparticles matched well with the tabulated data. Energy...

Nickel allergy

DEFF Research Database (Denmark)

Fischer, L A; Johansen, J D; Menné, T

2007-01-01

BACKGROUND: The frequency of nickel allergy varies between different population groups. Exposure regulation has proven effective in decreasing the frequency. Experimental studies with other allergens have shown a significant relation between patch test reactivity and repeated open application test...... in a patch test and a dilution series of three concentrations in a ROAT, with duration of up to 21 days. Eighteen persons with no nickel allergy were included as control group for the ROAT. RESULTS: The predicted dose which will elicit a reaction in 10% of allergic individuals was calculated to be 0......-response; indeed, there was no statistically significant difference. CONCLUSIONS: For elicitation of nickel allergy the elicitation threshold for the patch test is higher than the elicitation threshold (per application) for the ROAT, but is approximately the same as the accumulated elicitation threshold...

[In vitro comparison of root canal preparation with step-back technique and GT rotary file--a nickel-titanium engine driven rotary instrument system].

Science.gov (United States)

Krajczár, Károly; Tóth, Vilmos; Nyárády, Zoltán; Szabó, Gyula

2005-06-01

The aim of the authors' study was to compare the remaining root canal wall thickness and the preparation time of root canals, prepared either with step-back technique, or with GT Rotary File, an engine driven nickel-titanium rotary instrument system. Twenty extracted molars were decoronated. Teeth were divided in two groups. In Group 1 root canals were prepared with step-back technique. In Group 2 GT Rotary File System was utilized. Preoperative vestibulo-oral X-ray pictures were taken from all teeth with radiovisiograph (RVG). The final preparations at the mesiobuccal canals (MB) were performed with size #30 and palatinal/distal canals with size #40 instruments. Postoperative RVG pictures were taken ensuring the preoperative positioning. The working time was measured in seconds during each preparation. The authors also assessed the remaining root canal wall thickness at 3, 6 and 9 mm from the radiological apex, comparing the width of the canal walls of the vestibulo-oral projections on pre- and postoperative RVG pictures both mesially and buccally. The ratios of the residual and preoperative root canal wall thickness were calculated and compared. The largest difference was found at the MB canals of the coronal and middle third level of the root, measured on the distal canal wall. The ratio of the remaining dentin wall thickness at the coronal and the middle level in the case of step-back preparation was 0.605 and 0.754, and 0.824 and 0.895 in the cases of GT files respectively. The preparation time needed for GT Rotary File System was altogether 68.7% (MB) and 52.5% (D/P canals) of corresponding step-back preparation times. The use of GT Rotary File with comparison of standard step-back method resulted in a shortened preparation time and excessive damage of the coronal part of the root canal could be avoided.

Direct observation of hierarchical nucleation of martensite and size-dependent superelasticity in shape memory alloys.

Science.gov (United States)