Cellular growth and dislocation structures in laser-nitrided titanium

NARCIS (Netherlands)

Kloosterman, A.B.; Hosson, J.Th.M. De

1997-01-01

Transmission electron microscopic observations were made of different dislocation structures in laser-nitrided titanium. Equidistant edge dislocations in the bulk and periodic surface structures exhibit a periodicity within the same order of magnitude. An analysis is presented in which both periodic

Formation and characterization of titanium nitride and titanium carbide films prepared by reactive sputtering

International Nuclear Information System (INIS)

Sundgren, J.-E.

1982-01-01

Titanium has been reactively r.f. sputtered in mixed Ar-N 2 and Ar-CH 4 discharges on to substrates held at 775 K. The films obtained have been characterized by scanning electron microscopy, X-ray diffraction and by measurements of hardness and electrical resistivity. The compositions of the films have been determined using Auger electron spectroscopy. The processes occurring both on substrates and target surfaces have been studied and it is shown that the latter is of great importance for the composition and structure of deposited films. Titanium nitride films of full density and with electrical resistivity and hardness values close to those of bulk TiN were only obtained in a narrow range close to the stoichiometric composition. Titanium carbide films grown on non-biased substrates were found to have an open structure and thus a low density. A bias applied to the substrate, however, improved the quality of the films. It is also shown that the heat of formation of the compounds plays an important role in the formation of carbides and nitrides. A large value promotes the development of large grains and dense structures. (Auth.)

Tribological Properties of Surface-Textured and Plasma-Nitrided Pure Titanium Under Oil Lubrication Condition

Science.gov (United States)

Zhang, Baosen; Dong, Qiangsheng; Ba, Zhixin; Wang, Zhangzhong; Shi, Hancheng; Xue, Yanting

2018-01-01

Plasma nitriding was conducted as post-treatment for surface texture on pure titanium to obtain a continuous nitriding layer. Supersonic fine particles bombarding (SFPB) was carried out to prepare surface texture. The surface morphologies and chemical composition were analyzed using scanning electron microscope and energy disperse spectroscopy. The microstructures of modified layers were characterized by transmission electron microscope. The tribological properties of surface-textured and duplex-treated pure titanium under oil lubrication condition were systematically investigated in the ball-on-plate reciprocating mode. The effects of applied load and sliding velocity on the tribological behavior were analyzed. The results show that after duplex treatments, the grains size in modified layer becomes slightly larger, and hardness is obviously improved. Wear resistance of duplex-treated pure titanium is significantly improved referenced to untreated and surface-textured pure titanium, which is 3.22 times as much as untreated pure titanium and 2.15 times of that for surface-textured pure titanium, respectively.

Anti corrosion layer for stainless steel in molten carbonate fuel cell - comprises phase vapour deposition of titanium nitride, aluminium nitride or chromium nitride layer then oxidising layer in molten carbonate electrolyte

DEFF Research Database (Denmark)

2000-01-01

Forming an anticorrosion protective layer on a stainless steel surface used in a molten carbonate fuel cell (MCFC) - comprises the phase vapour deposition (PVD) of a layer comprising at least one of titanium nitride, aluminium nitride or chromium nitride and then forming a protective layer in situ...

Mesoporous coaxial titanium nitride-vanadium nitride fibers of core-shell structures for high-performance supercapacitors.

Science.gov (United States)

Zhou, Xinhong; Shang, Chaoqun; Gu, Lin; Dong, Shanmu; Chen, Xiao; Han, Pengxian; Li, Lanfeng; Yao, Jianhua; Liu, Zhihong; Xu, Hongxia; Zhu, Yuwei; Cui, Guanglei

2011-08-01

In this study, titanium nitride-vanadium nitride fibers of core-shell structures were prepared by the coaxial electrospinning, and subsequently annealed in the ammonia for supercapacitor applications. These core-shell (TiN-VN) fibers incorporated mesoporous structure into high electronic conducting transition nitride hybrids, which combined higher specific capacitance of VN and better rate capability of TiN. These hybrids exhibited higher specific capacitance (2 mV s(-1), 247.5 F g(-1)) and better rate capability (50 mV s(-1), 160.8 F g(-1)), which promise a good candidate for high-performance supercapacitors. It was also revealed by electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) characterization that the minor capacitance fade originated from the surface oxidation of VN and TiN.

Waste conversion into high-value ceramics: Carbothermal nitridation synthesis of titanium nitride nanoparticles using automotive shredder waste.

Science.gov (United States)

Mayyas, Mohannad; Pahlevani, Farshid; Maroufi, Samane; Liu, Zhao; Sahajwalla, Veena

2017-03-01

Environmental concern about automotive shredder residue (ASR) has increased in recent years due to its harmful content of heavy metals. Although several approaches of ASR management have been suggested, these approaches remain commercially unproven. This study presents an alternative approach for ASR management where advanced materials can be generated as a by-product. In this approach, titanium nitride (TiN) has been thermally synthesized by nitriding pressed mixture of automotive shredder residue (ASR) and titanium oxide (TiO 2 ). Interactions between TiO 2 and ASR at non-isothermal conditions were primarily investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry. Results indicated that TiO 2 influences and catalyses degradation reactions of ASR, and the temperature, at which reduction starts, was determined around 980 °C. The interaction between TiO 2 and ASR at isothermal conditions in the temperature range between 1200 and 1550 °C was also studied. The pressed mixture of both materials resulted in titanium nitride (TiN) ceramic at all given temperatures. Formation kinetics were extracted using several models for product layer diffusion-controlled solid-solid and solid-fluid reactions. The effect of reactants ratio and temperature on the degree of conversion and morphology was investigated. The effect of reactants ratio was found to have considerable effect on the morphology of the resulting material, while temperature had a lesser impact. Several unique structures of TiN (porous nanostructured, polycrystalline, micro-spherical and nano-sized structures) were obtained by simply tuning the ratio of TiO 2 to ASR, and a product with appreciable TiN content of around 85% was achieved after only one hour nitridation at 1550 °C. Copyright © 2016 Elsevier Ltd. All rights reserved.

Titanium Nitride and Nitrogen Ion Implanted Coated Dental Materials

Directory of Open Access Journals (Sweden)

David W. Berzins

2012-07-01

Full Text Available Titanium nitride and/or nitrogen ion implanted coated dental materials have been investigated since the mid-1980s and considered in various applications in dentistry such as implants, abutments, orthodontic wires, endodontic files, periodontal/oral hygiene instruments, and casting alloys for fixed restorations. Multiple methodologies have been employed to create the coatings, but detailed structural analysis of the coatings is generally lacking in the dental literature. Depending on application, the purpose of the coating is to provide increased surface hardness, abrasion/wear resistance, esthetics, and corrosion resistance, lower friction, as well as greater beneficial interaction with adjacent biological and material substrates. While many studies have reported on the achievement of these properties, a consensus is not always clear. Additionally, few studies have been conducted to assess the efficacy of the coatings in a clinical setting. Overall, titanium nitride and/or nitrogen ion implanted coated dental materials potentially offer advantages over uncoated counterparts, but more investigation is needed to document the structure of the coatings and their clinical effectiveness.

Electrochemical capacitance performance of titanium nitride nanoarray

Energy Technology Data Exchange (ETDEWEB)

Xie, Yibing, E-mail: ybxie@seu.edu.cn [School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China); Suzhou Research Institute of Southeast University, Suzhou 215123 (China); Wang, Yong [School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China); Du, Hongxiu [School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China); Suzhou Research Institute of Southeast University, Suzhou 215123 (China)

2013-12-01

Highlights: • TiN nanoarray is formed by a nitridation process of TiO{sub 2} in ammonia atmosphere. • TiN nanoarray exhibits much higher EDLC capacitance than TiO{sub 2} nanoarray. • The specific capacitance of TiN nanoarray achieves a high level of 99.7 mF cm{sup −2}. • A flexible solid-state supercapacitor is constructed by TiN nanoarray and PVA gel. -- Abstract: In this study, titanium nitride (TiN) nanoarrays with a short nanotube and long nanopore structure have been prepared by an anodization process of ultra thin titanium foil in ethylene glycol (EG) solution containing ammonium fluoride, subsequent calcination process in an air atmosphere, and final nitridation process in an ammonia atmosphere. The morphology and microstructure characterization has been conducted using field emission scanning electron microscope and X-ray diffraction. The electrochemical properties have been investigated through cyclic voltammetry and electrochemical impedance spectrum measurements. The electrochemical capacitance performance has been investigated by galvanostatic charge–discharge measurements in the acidic, neural and alkali electrolyte solution. Well-defined TiN nanoarrays contribute a much higher capacitance performance than titania (TiO{sub 2}) in the supercapacitor application due to the extraordinarily improved electrical conductivity. Such an electrochemical capacitance can be further enhanced by increasing aspect ratio of TiN nanoarray from short nanotubes to long nanopores. A flexible supercapacitor has been constructed using two symmetrical TiN nanoarray electrodes and a polyvinyl alcohol (PVA) gel electrolyte with H{sub 2}SO{sub 4}–KCl–H{sub 2}O–EG. Such a supercapacitor has a highly improved potential window and still keeps good electrochemical energy storage. TiN nanoarray with a high aspect ratio can act well as an ultra thin film electrode material of flexible supercapacitor to contribute a superior capacitance performance.

Titanium nitride coatings synthesized by IPD method with eliminated current oscillations

Directory of Open Access Journals (Sweden)

Chodun Rafał

2016-09-01

Full Text Available This paper presents the effects of elimination of current oscillations within the coaxial plasma accelerator during IPD deposition process on the morphology, phase structure and properties of synthesized TiN coatings. Current observations of waveforms have been made by use of an oscilloscope. As a test material for experiments, titanium nitride TiN coatings synthesized on silicon and high-speed steel substrates were used. The coatings morphology, phase composition and wear resistance properties were determined. The character of current waveforms in the plasma accelerator electric circuit plays a crucial role during the coatings synthesis process. Elimination of the current oscillations leads to obtaining an ultrafine grained structure of titanium nitride coatings and to disappearance of the tendency to structure columnarization. The coatings obtained during processes of a non-oscillating character are distinguished by better wear-resistance properties.

Laser beam welding of titanium nitride coated titanium using pulse-shaping

Directory of Open Access Journals (Sweden)

Milton Sergio Fernandes de Lima

2005-09-01

Full Text Available A new welding method which allows the assembly of two titanium nitride coated titanium parts is proposed. The welding procedure utilizes the possibility for pulse-shaping in order to change the energy distribution profile during the laser pulse. The pulse-shaping is composed of three elements: a a short high power pulse for partial ablation at the surface; b a long pulse for thermal penetration; and c a quenching slope for enhanced weldability. The combination of these three elements produces crack-free welds. The weld microstructure is changed in comparison to normal welding, i.e. with a rectangular pulse, as the nitrogen and the microhardness are more homogenously distributed in the weld under pulse-shaping conditions. This laser pulse dissolves the TiN layer and allows nitrogen to diffuse into the melt pool, also contributing to an enhanced weldability by providing suitable thermal conditions.

Aspects of the practical application of titanium alloys after low temperature nitriding glow discharge in hydrogen- free -gas media

International Nuclear Information System (INIS)

Mashovets, N.S.; Pastukh, I.M.; Voloshko, S.M.

2017-01-01

Highlights: • Surface modification of titanium alloys were carried out by low-temperature nitriding in a glow discharge in hydrogen-free environment. • Research into the phase composition was performed by X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). • The above material shows the promise of the technology of low-temperature hydrogen-nitriding by glow discharge. This greatly expands the range of practical applications of titanium alloys. - Abstract: X-ray diffraction analysis, X-ray photoelectron spectroscopy, and Electron Auger-spectroscopy investigation of phase transformation on the surface of the VT8 titanium alloy after a low temperature hydrogen-free nitriding in a glow discharge. Operational characteristics of titanium alloys defined physical-mechanical characteristics of the surface and their phase composition, which depend on the process parameters of nitriding. Surface modification of titanium alloys were carried out by low-temperature nitriding in a glow discharge in hydrogen-free environment. The main advantage of this method lies in the absence of hydrogen embrittlement and complete environmental safety process. Application of the glow discharge can not only speed up the process by the order of the diffusion surface saturation with nitrogen, but also significantly alters the kinetics of the process and quality of the nitrided layer, in particular its physio-mechanical properties and phase composition. For research purposes, the standards from an α + β alloy Ti-Al6-Cr2-Mo2,5 (VT8) were used. Research into the phase composition was performed by X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Stratified analysis by AES was conducted by etching the surface of the samples’ argon ion beam with diameters of 1.5 mm with an energy of 3000 eV and a current density of 400 mA/cm 2 . The above material shows the promise of the technology of low

Aspects of the practical application of titanium alloys after low temperature nitriding glow discharge in hydrogen- free -gas media

Energy Technology Data Exchange (ETDEWEB)

Mashovets, N.S., E-mail: mashovets@rambler.ru [Khmelnickiy National University (Ukraine); Pastukh, I.M., E-mail: pastim@mail.ru [Khmelnickiy National University (Ukraine); Voloshko, S.M. [Khmelnickiy National University (Ukraine); National Technical University of Ukraine “Kyiv Polytechnic Institute” (Ukraine)

2017-01-15

Highlights: • Surface modification of titanium alloys were carried out by low-temperature nitriding in a glow discharge in hydrogen-free environment. • Research into the phase composition was performed by X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). • The above material shows the promise of the technology of low-temperature hydrogen-nitriding by glow discharge. This greatly expands the range of practical applications of titanium alloys. - Abstract: X-ray diffraction analysis, X-ray photoelectron spectroscopy, and Electron Auger-spectroscopy investigation of phase transformation on the surface of the VT8 titanium alloy after a low temperature hydrogen-free nitriding in a glow discharge. Operational characteristics of titanium alloys defined physical-mechanical characteristics of the surface and their phase composition, which depend on the process parameters of nitriding. Surface modification of titanium alloys were carried out by low-temperature nitriding in a glow discharge in hydrogen-free environment. The main advantage of this method lies in the absence of hydrogen embrittlement and complete environmental safety process. Application of the glow discharge can not only speed up the process by the order of the diffusion surface saturation with nitrogen, but also significantly alters the kinetics of the process and quality of the nitrided layer, in particular its physio-mechanical properties and phase composition. For research purposes, the standards from an α + β alloy Ti-Al6-Cr2-Mo2,5 (VT8) were used. Research into the phase composition was performed by X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Stratified analysis by AES was conducted by etching the surface of the samples’ argon ion beam with diameters of 1.5 mm with an energy of 3000 eV and a current density of 400 mA/cm{sup 2}. The above material shows the promise of the technology of low

The Importance Of Surface Topography For The Biological Properties Of Nitrided Diffusion Layers Produced On Ti6Al4V Titanium Alloy

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Wierzchoń T.

2015-09-01

Full Text Available Diffusion nitrided layers produced on titanium and its alloys are widely studied in terms of their application for cardiac and bone implants. The influence of the structure, the phase composition, topography and surface morphology on their biological properties is being investigated. The article presents the results of a study of the topography (nanotopography of the surface of TiN+Ti2N+αTi(N nitrided layers produced in low-temperature plasma on Ti6Al4V titanium alloy and their influence on the adhesion of blood platelets and their aggregates. The TEM microstructure of the produced layers have been examined and it was demonstrated that the interaction between platelets and the surface of the titanium implants subjected to glow-discharge nitriding can be shaped via modification of the roughness parameters of the external layer of the TiN titanium nitride nanocrystalline zone.

High performance corrosion and wear resistant composite titanium nitride layers produced on the AZ91D magnesium alloy by a hybrid method

Directory of Open Access Journals (Sweden)

Michał Tacikowski

2014-09-01

Full Text Available Composite, diffusive titanium nitride layers formed on a titanium and aluminum sub-layer were produced on the AZ91D magnesium alloy. The layers were obtained using a hybrid method which combined the PVD processes with the final sealing by a hydrothermal treatment. The microstructure, resistance to corrosion, mechanical damage, and frictional wear of the layers were examined. The properties of the AZ91D alloy covered with these layers were compared with those of the untreated alloy and of some engineering materials such as 316L stainless steel, 100Cr6 bearing steel, and the AZ91D alloy subjected to commercial anodizing. It has been found that the composite diffusive nitride layer produced on the AZ91D alloy and then sealed by the hydrothermal treatment ensures the corrosion resistance comparable with that of 316L stainless steel. The layers are characterized by higher electrochemical durability which is due to the surface being overbuilt with the titanium oxides formed, as shown by the XPS examinations, from titanium nitride during the hydrothermal treatment. The composite titanium nitride layers exhibit high resistance to mechanical damage and wear, including frictional wear which is comparable with that of 100Cr6 bearing steel. The performance properties of the AZ91D magnesium alloy covered with the composite titanium nitride coating are substantially superior to those of the alloy subjected to commercial anodizing which is the dominant technique employed in industrial practice.

Bacterial adhesion studies on titanium, titanium nitride and modified hydroxyapatite thin films

Energy Technology Data Exchange (ETDEWEB)

Jeyachandran, Y L [Department of Physics, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India); Venkatachalam, S [Department of Physics, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India); Karunagaran, B [Department of Physics, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India); Narayandass, Sa K [Department of Physics, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India); Mangalaraj, D [Department of Physics, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India); Bao, C Y [West China College of Stomatology, Sichuan University, Chengdu 610041 (China); Zhang, C L [West China College of Stomatology, Sichuan University, Chengdu 610041 (China)

2007-01-15

A qualitative study on adhesion of the oral bacteria Porphyromonas gingivalis on titanium (Ti), titanium nitride (TiN), fluorine modified hydroxyapatite (FHA) and zinc modified FHA (Zn-FHA) thin films is investigated. Ti and TiN thin films were deposited by DC magnetron sputtering and hydroxyapatite-based films were prepared by solgel method. The crystalline structure, optical characteristics, chemical composition and surface topography of the films were studied by XRD, optical transmission, XPS, EDAX and AFM measurements. The predominant crystallite orientation in the Ti and TiN films was along (002) and (111) of hcp and cubic structures, respectively. The Ti : O : N composition ratio in the surface of the Ti and TiN films was found to be 7 : 21 : 1 and 3 : 8 : 2, respectively. The atomic concentration ratio (Zn + Ca) / P in Zn-FHA film was found to be 1.74 whereby the Zn replaced 3.2% of Ca. The rough surface feature in modified HA films was clearly observed in the SEM images and the surface roughness (rms) of Ti and TiN films was 2.49 and 3.5 nm, respectively, as observed using AFM. The film samples were sterilized, treated in the bacteria culture medium, processed and analyzed using SEM. Surface roughness of the films was found to have least influence on the bacterial adhesion. More bacteria were observed on the TiN film with oxide nitride surface layer and less number of adhered bacteria was noticed on the Ti film with native surface oxide layer and on Zn-FHA film.

Bacterial adhesion studies on titanium, titanium nitride and modified hydroxyapatite thin films

International Nuclear Information System (INIS)

Jeyachandran, Y.L.; Venkatachalam, S.; Karunagaran, B.; Narayandass, Sa.K.; Mangalaraj, D.; Bao, C.Y.; Zhang, C.L.

2007-01-01

A qualitative study on adhesion of the oral bacteria Porphyromonas gingivalis on titanium (Ti), titanium nitride (TiN), fluorine modified hydroxyapatite (FHA) and zinc modified FHA (Zn-FHA) thin films is investigated. Ti and TiN thin films were deposited by DC magnetron sputtering and hydroxyapatite-based films were prepared by solgel method. The crystalline structure, optical characteristics, chemical composition and surface topography of the films were studied by XRD, optical transmission, XPS, EDAX and AFM measurements. The predominant crystallite orientation in the Ti and TiN films was along (002) and (111) of hcp and cubic structures, respectively. The Ti : O : N composition ratio in the surface of the Ti and TiN films was found to be 7 : 21 : 1 and 3 : 8 : 2, respectively. The atomic concentration ratio (Zn + Ca) / P in Zn-FHA film was found to be 1.74 whereby the Zn replaced 3.2% of Ca. The rough surface feature in modified HA films was clearly observed in the SEM images and the surface roughness (rms) of Ti and TiN films was 2.49 and 3.5 nm, respectively, as observed using AFM. The film samples were sterilized, treated in the bacteria culture medium, processed and analyzed using SEM. Surface roughness of the films was found to have least influence on the bacterial adhesion. More bacteria were observed on the TiN film with oxide nitride surface layer and less number of adhered bacteria was noticed on the Ti film with native surface oxide layer and on Zn-FHA film

A study of nitride formation during the oxidation of titanium-tantalum alloys

International Nuclear Information System (INIS)

Hanrahan, R.J. Jr.; Lu, Y.C.; Kung, H.; Butt, D.P.

1996-01-01

The oxidation rates of Ti rich titanium-tantalum alloys are significantly lower in air than in oxygen. This nitrogen effect has been shown to be associated with the formation of a nitride layer at or near the scale-metal interface. In the present work the authors used transmission electron microscopy and microdiffraction to identify the nitrides formed on Ti5Ta and Ti40Ta (5 and 40 weight percent Ta alloys) during identical exposures. In both alloys the nitride develops in contact with the oxygen stabilized α-phase in the substrate. In Ti5Ta a continuous layer of TiN forms, while in Ti40Ta a discontinuous layer of Ti 2 N interspersed with Ta 2 O 5 (formed from the Ta rich β-phase) is formed. The nitride layer acts as an oxygen diffusion barrier, reducing the dissolution of oxygen in the substrate

Elaboration of titanium nitride coatings by activated reactive evaporation

International Nuclear Information System (INIS)

Granier, Jean

1978-01-01

As titanium nitride is a very interesting and promising material for the protection against wear and corrosion of metals and alloys with a low fusion point, and notably steels, this research thesis reports the study of the elaboration of a TiN coating by activated reactive evaporation. In a first part, the author describes deposition processes based on evaporation and their characteristics. He explains the choice of the studied process. He discusses published data and results related to the titanium-nitrogen system. He describes the apparatus and reports the operation mode adjustment, and reports the study of the influence of operating conditions (substrate temperature, nitrogen pressure, evaporation rate, possible use of a discharge) on growth kinetics and on coating properties. A reaction mechanism is then proposed to describe and explain the obtained results [fr

[Experimental study on the corrosion behavior of a type of oral near β-type titanium alloys modified with double glow plasma nitriding].

Science.gov (United States)

Wen, Ke; Li, Fenglan

2015-12-01

To study the electrochemical corrosion performance of a type of biomedical materials near beta titanium alloy(Ti-3Zr-2Sn-3Mo-25Nb, TLM) in artificial saliva before and after nitride changing, and to provide clinical basis for clinical application of titanium alloy TLM. The double glow plasma alloying technology was used to nitride the surface of titanium alloy TLM. The surface properties of the modified layer were observed and tested by optical microscope, scanning electron microscope, glow discharge spectrum analyzer, X-ray diffraction and micro hardness tester. Then, electrochemical measurement system was used to test and compare titanium alloy TLM's electrochemical corrosion in artificial saliva before and after its surface change. Finally, the surface morphology of the original titanium alloy and the modified layer was compared by scanning electron microscope. By the technology of double glow plasma nitriding, the surface of the titanium alloy TLM had been successfully nitrided with a modified layer of 4-5 µm in thickness, uniform and compact. Its main compositions were Ti and Ti(2)N. The Microhardness of modified layer also had been improved from (236.8 ± 5.4) to (871.8 ± 5.2) HV. The self-corrosion potential in electrochemical corrosion tests had been increased from -0.559 V to -0.540 V, while the self- corrosion current density had been reduced from 2.091 × 10(-7) A/cm(2) to 7.188 × 10(-8) A/cm(2). Besides, alternating-current impedance(AC Impedance) had also been increased. With the scanning electron microscope, it's obvious that the diameter of corrosion holes on modified layer were approximately 10 µm. As to the diameter and number of corrosion holes on modified layer, they had been decreased comparing with the original titanium alloy. The type of near beta titanium alloy TLM can construct a nitriding modified layer on its surface. Meanwhile, the performance of its anti- corrosion in artificial saliva has been improved, comparing to the original

Titanium nitride deposition in titanium implant alloys produced by powder metallurgy

International Nuclear Information System (INIS)

Henriques, V.A.R.; Cairo, C.A.A.; Faria, J.; Lemos, T.G.; Galvani, E.T.

2009-01-01

Titanium nitride (TiN) is an extremely hard material, often used as a coating on titanium alloy, steel, carbide, and aluminum components to improve wear resistance. Electron Beam Physical Vapor Deposition (EB-PVD) is a form of deposition in which a target anode is bombarded with an electron beam given off by a charged tungsten filament under high vacuum, producing a thin film in a substrate. In this work are presented results of TiN deposition in targets and substrates of Ti (C.P.) and Ti- 13 Nb- 13 Zr obtained by powder metallurgy. Samples were produced by mixing of hydride metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering between 900°C up to 1400 °C, in vacuum. The deposition was carried out under nitrogen atmosphere. Sintered samples were characterized for phase composition, microstructure and microhardness by X-ray diffraction, scanning electron microscopy and Vickers indentation, respectively. It was shown that the samples were sintered to high densities and presented homogeneous microstructure, with ideal characteristics for an adequate deposition and adherence. The film layer presented a continuous structure with 15μm. (author)

Preparation of Titanium nitride nanomaterials for electrode and application in energy storage

Directory of Open Access Journals (Sweden)

Shun Tang

Full Text Available The Titanium nitride was made by the carbamide and titanic chloride precursors. XRD results indicate that the precursor ratio N:Ti 3:1 leads to higher crystallinity. SEM and EDX demonstrated that Ti and N elements were distributed uniformly with the ratio of 1:1. The TiN used as the electrode material for supercapacitor was also studied. The specific capacities were changed from 407 F.g−1 to 385 F.g−1, 364 F.g−1 and 312 F.g−1, when the current densities were changed from 1 A.g−1 to 2 A.g−1, 5 A.g−1 and 10 A.g−1, respectively. Chronopotentiometry tests showed high coulombic efficiency. Cycling performance of the TiN electrode was evaluated by CV at a scanning rate of 50 mV.s−1 for 20,000 cycles and there was about 9.8% loss. These results indicate that TiN is a promising electrode material for the supercapacitors. Keywords: Energy storage, Nanomaterials, Anode, Titanium nitride, Supercapacitors

Bone response to a titanium aluminium nitride coating on metallic implants.

Science.gov (United States)

Freeman, C O; Brook, I M

2006-05-01

The design, surface characteristics and strength of metallic implants are dependant on their intended use and clinical application. Surface modifications of materials may enable reduction of the time taken for osseointegration and improve the biological response of bio-mechanically favourable metals and alloys. The influence of a titanium aluminium nitride (TAN) coating on the response of bone to commercially pure titanium and austenitic 18/8 stainless steel wire is reported. TAN coated and plain rods of stainless steel and commercially pure titanium were implanted into the mid-shaft of the femur of Wistar rats. The femurs were harvested at four weeks and processed for scanning electron and light microscopy. All implants exhibited a favourable response in bone with no evidence of fibrous encapsulation. There was no significant difference in the amount of new bone formed around the different rods (osseoconduction), however, there was a greater degree of shrinkage separation of bone from the coated rods than from the plain rods (p = 0.017 stainless steel and p = 0.0085 titanium). TAN coating may result in reduced osseointegration between bone and implant.

Coating of Titanium Nitride on Stainless Steel Targets by a 4 kJ Plasma Focus Device

Science.gov (United States)

Omrani, M.; Habibi, M.; Amrollahi, R.

2012-08-01

Titanium nitride thin films were deposited on stainless steel (SS316L) targets by using a 4 kJ plasma focus device. The corresponding energy flux delivered to SS316L surface is estimated to be 2.69 × 1013 kev cm-3 ns-1. X-ray diffraction analysis reveals the formation of a nanocrystalline titanium nitride coating on the surface of targets. Thickness of the elements found on the surface of treated samples which are obtained by Rutherford backscattering spectrometry analysis (RBS) were (×1015 at/cm2) .45% Ti, 50% N and 5% Fe. Scanning electron microscopy was used to indicate changes in surface morphology. Existence of grains in different size confirms the formation of TiN crystals on the surface of targets.

Atmospheric pressure chemical vapour deposition of the nitrides and oxynitrides of vanadium, titanium and chromium

International Nuclear Information System (INIS)

Elwin, G.S.

1999-01-01

A study has been made into the atmospheric pressure chemical vapour deposition of nitrides and oxynitrides of vanadium, titanium and chromium. Vanadium tetrachloride, vanadium oxychloride, chromyl chloride and titanium tetrachloride have been used as precursors with ammonia, at different flow conditions and temperatures. Vanadium nitride, vanadium oxynitride, chromium oxynitride, titanium/vanadium nitride and titanium/chromium oxynitride have been deposited as thin films on glass. The APCVD reaction of VCl 4 and ammonia leads to films with general composition VN x O y . By raising the ammonia concentration so that it is in excess (0.42 dm 3 min -1 VCl 4 with 1.0 dm 3 min -1 NH 3 at 500 deg. C) a film has been deposited with the composition VN 0.8 O 0.2 . Further investigation discovered similar elemental compositions could be reached by deposition at 350 deg. C (0.42 dm 3 min -1 VCl 4 with 0.5 dm 3 min -1 NH 3 ), followed by annealing at 650 deg. C, and cooled under a flow of ammonia. Only films formed below 400 deg. C were found to contain carbon or chlorine ( 3 and ammonia also lead to films of composition VN x O y the oxygen to nitrogen ratios depending on the deposition conditions. The reaction Of VOCl 3 (0.42 dm 3 min -1 ) and ammonia (0.2 dm 3 min -1 ) at 500 deg. C lead to a film of composition VN 0. 47O 1.06 . The reaction of VOCl 3 (0.42 dm 3 min -1 ) and ammonia (0.5 dm 3 min -1 ) at 650 deg. C lead to a film of composition VN 0.63 O 0.41 . The reaction of chromyl chloride with excess ammonia led to the formation of chromium oxide (Cr 2 O 3 ) films. Mixed metal films were prepared from the reactions of vanadium tetrachloride, titanium tetrachloride and ammonia to prepare V x Ti y N z and chromyl chloride, titanium tetrachloride and ammonia to form TiCr x O y N z . Both reactions produced the intended mixed coating but it was found that the vanadium / titanium nitride contained around 10 % vanadium whatever the conditions used. Oxygen contamination

Fabrication and Physical Properties of Titanium Nitride/Hydroxyapatite Composites on Polyether Ether Ketone by RF Magnetron Sputtering Technique

Science.gov (United States)

Nupangtha, W.; Boonyawan, D.

2017-09-01

Titanium nitride (TiN) coatings have been used very successfully in a variety of applications because of their excellent properties, such as the high hardness meaning good wear resistance and also used for covering medical implants. Hydroxyapatite is a bioactive ceramic that contributes to the restoration of bone tissue, which together with titanium nitride may contribute to obtaining a superior composite in terms of mechanical and bone tissue interaction matters. This paper aims to explain how to optimize deposition conditions for films synthesis on PEEK by varying sputtering parameters such as nitrogen flow rate and direction, deposition time, d-s (target-to-substrate distance) and 13.56 MHz RF power. The plasma conditions used to deposit films were monitored by the optical emission spectroscopy (OES). Titanium nitride/Hydroxyapatite composite films were performed by gas mixture with nitrogen and argon ratio of 1:3 and target-to-substrate distance at 8 cm. The gold colour, as-deposited film was found on PEEK with high hardness and higher surface energy than uncoated PEEK. X-ray diffraction characterization study was carried to study the crystal structural properties of these composites.

Development of novel titanium nitride-based decorative coatings by calcium addition

Energy Technology Data Exchange (ETDEWEB)

Hodroj, A. [Institut Jean Lamour, CNRS UMR 7198, Departement CP2S, Ecole des Mines, Parc de Saurupt, CS 14234, 54042 Nancy cedex (France); Pierson, J.F., E-mail: jean-francois.pierson@ijl.nancy-universite.fr [Institut Jean Lamour, CNRS UMR 7198, Departement CP2S, Ecole des Mines, Parc de Saurupt, CS 14234, 54042 Nancy cedex (France)

2011-08-01

Calcium was added into titanium nitride coatings deposited using a hybrid magnetron sputtering-arc evaporation process. The calcium content in the films was adjusted by the variation of the pulsed DC current applied to the Ca sputtering target. X-ray diffraction analyses suggested that the increase of the calcium content induced the partial substitution of titanium atoms by calcium ones in the TiN lattice and a refinement of the grain size. Optical reflectance investigations showed that the absorption band of TiN was shifted towards higher wavelengths and that (Ti,Ca)N coatings may be suitable for decorative applications. Finally, the decrease of the film reflectivity was interpreted as a consequence of a free electron concentration decrease as confirmed from electrical resistivity measurements.

Development of novel titanium nitride-based decorative coatings by calcium addition

International Nuclear Information System (INIS)

Hodroj, A.; Pierson, J.F.

2011-01-01

Calcium was added into titanium nitride coatings deposited using a hybrid magnetron sputtering-arc evaporation process. The calcium content in the films was adjusted by the variation of the pulsed DC current applied to the Ca sputtering target. X-ray diffraction analyses suggested that the increase of the calcium content induced the partial substitution of titanium atoms by calcium ones in the TiN lattice and a refinement of the grain size. Optical reflectance investigations showed that the absorption band of TiN was shifted towards higher wavelengths and that (Ti,Ca)N coatings may be suitable for decorative applications. Finally, the decrease of the film reflectivity was interpreted as a consequence of a free electron concentration decrease as confirmed from electrical resistivity measurements.

No clinical benefit of titanium nitride coating in cementless mobile-bearing total knee arthroplasty

NARCIS (Netherlands)

van Hove, R.P.; Brohet, R.M.; van Royen, B.J.; Nolte, P.A.

2015-01-01

Purpose: Titanium nitride (TiN) coating of cobalt–chromium–molybdenum (CoCrMo) implants has shown to improve the biomechanical properties of the implant surface and to reduce adhesive wear in vitro. It is yet unknown whether TiN coating of total knee prosthesis (TKP) affects the postoperative

Electron heating by photon-assisted tunneling in niobium terahertz mixers with integrated niobium titanium nitride striplines

NARCIS (Netherlands)

Leone, B; Gao, [No Value; Klapwijk, TM; Jackson, BD; Laauwen, WM; de Lange, G

2001-01-01

We describe the gap voltage depression and current-voltage (I-V) characteristics in pumped niobium superconductor-insulator-superconductor junction with niobium titanium nitride tuning stripline by introducing an electron heating power contribution resulting from the photon-assisted tunneling

Fully CMOS-compatible titanium nitride nanoantennas

Energy Technology Data Exchange (ETDEWEB)

Briggs, Justin A., E-mail: jabriggs@stanford.edu [Department of Applied Physics, Stanford University, 348 Via Pueblo Mall, Stanford, California 94305 (United States); Department of Materials Science and Engineering, Stanford University, 496 Lomita Mall, Stanford, California 94305 (United States); Naik, Gururaj V.; Baum, Brian K.; Dionne, Jennifer A. [Department of Materials Science and Engineering, Stanford University, 496 Lomita Mall, Stanford, California 94305 (United States); Petach, Trevor A.; Goldhaber-Gordon, David [Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305 (United States)

2016-02-01

CMOS-compatible fabrication of plasmonic materials and devices will accelerate the development of integrated nanophotonics for information processing applications. Using low-temperature plasma-enhanced atomic layer deposition (PEALD), we develop a recipe for fully CMOS-compatible titanium nitride (TiN) that is plasmonic in the visible and near infrared. Films are grown on silicon, silicon dioxide, and epitaxially on magnesium oxide substrates. By optimizing the plasma exposure per growth cycle during PEALD, carbon and oxygen contamination are reduced, lowering undesirable loss. We use electron beam lithography to pattern TiN nanopillars with varying diameters on silicon in large-area arrays. In the first reported single-particle measurements on plasmonic TiN, we demonstrate size-tunable darkfield scattering spectroscopy in the visible and near infrared regimes. The optical properties of this CMOS-compatible material, combined with its high melting temperature and mechanical durability, comprise a step towards fully CMOS-integrated nanophotonic information processing.

Corrosion resistance of a magnetic stainless steel ion-plated with titanium nitride.

Science.gov (United States)

Hai, K; Sawase, T; Matsumura, H; Atsuta, M; Baba, K; Hatada, R

2000-04-01

This in vitro study evaluated the corrosion resistance of a titanium nitride (TiN) ion-plated magnetic stainless steel (447J1) for the purpose of applying a magnetic attachment system to implant-supported prostheses made of titanium. The surface hardness of the TiN ion-plated 447J1 alloy with varying TiN thickness was determined prior to the corrosion testing, and 2 micrometers thickness was confirmed to be appropriate. Ions released from the 447J1 alloy, TiN ion-plated 447J1 alloy, and titanium into a 2% lactic acid aqueous solution and 0.1 mol/L phosphate buffered saline (PBS) were determined by means of an inductively coupled plasma atomic emission spectroscopy (ICP-AES). Long-term corrosion behaviour was evaluated using a multisweep cyclic voltammetry. The ICP-AES results revealed that the 447J1 alloy released ferric ions into both media, and that the amount of released ions increased when the alloy was coupled with titanium. Although both titanium and the TiN-plated 447J1 alloy released titanium ions into lactic acid solution, ferric and chromium ions were not released from the alloy specimen for all conditions. Cyclic voltamograms indicated that the long-term corrosion resistance of the 447J1 alloy was considerably improved by ion-plating with TiN.

On the difference between optically and electrically determined resistivity of ultra-thin titanium nitride films

NARCIS (Netherlands)

Van Hao, B.; Kovalgin, Alexeij Y.; Wolters, Robertus A.M.

2013-01-01

This work reports on the determination and comparison of the resistivity of ultra-thin atomic layer deposited titanium nitride films in the thickness range 0.65–20 nm using spectroscopic ellipsometry and electrical test structures. We found that for films thicker than 4 nm, the resistivity values

Leachability of nitrided ilmenite in hydrochloric acid

OpenAIRE

Swanepoel, J.J.; van Vuuren, D.S.; Heydenrych, M.

2011-01-01

Titanium nitride in upgraded nitrided ilmenite (bulk of iron removed) can selectively be chlorinated to produce titanium tetrachloride. Except for iron, most other components present during this low temperature (ca. 200°C) chlorination reaction will not react with chlorine. It is therefore necessary to remove as much iron as possible from the nitrided ilmenite. Hydrochloric acid leaching is a possible process route to remove metallic iron from nitrided ilmenite without excessive dissolution o...

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.

Plasma synthesis of titanium nitride, carbide and carbonitride nanoparticles by means of reactive anodic arc evaporation from solid titanium

International Nuclear Information System (INIS)

Kiesler, D.; Bastuck, T.; Theissmann, R.; Kruis, F. E.

2015-01-01

Plasma methods using the direct evaporation of a transition metal are well suited for the cost-efficient production of ceramic nanoparticles. In this paper, we report on the development of a simple setup for the production of titanium-ceramics by reactive anodic arc evaporation and the characterization of the aerosol as well as the nanopowder. It is the first report on TiC X N 1 − X synthesis in a simple anodic arc plasma. By means of extensive variations of the gas composition, it is shown that the composition of the particles can be tuned from titanium nitride over a titanium carbonitride phase (TiC X N 1 − X ) to titanium carbide as proven by XRD data. The composition of the plasma gas especially a very low concentration of hydrocarbons around 0.2 % of the total plasma gas is crucial to tune the composition and to avoid the formation of free carbon. Examination of the particles by HR-TEM shows that the material consists mostly of cubic single crystalline particles with mean sizes between 8 and 27 nm

Leachability of nitrided ilmenite in hydrochloric acid

CSIR Research Space (South Africa)

Swanepoel, JJ

2010-10-01

Full Text Available Titanium nitride in upgraded nitrided ilmenite (bulk of iron removed) can selectively be chlorinated to produce titanium tetrachloride. Except for iron, most other components present during this low temperature (ca. 200 °C) chlorination reaction...

Xenon thermal behavior in sintered titanium nitride, foreseen inert matrix for GFR

International Nuclear Information System (INIS)

Bes, R.

2010-11-01

This work concerns the generation IV future nuclear reactors such as gas-cooled fast reactor (GFR) for which refractory materials as titanium nitride (TiN) are needed to surround fuel and act as a fission product diffusion barrier. This study is about Xe thermal behavior in sintered titanium nitride. Microstructure effects on Xe behavior have been studied. In this purpose, several syntheses have been performed using different sintering temperatures and initial powder compositions. Xenon species have been introduced into samples by ionic implantation. Then, samples were annealed in temperature range from 1300 C to 1600 C, these temperatures being the accidental awaited temperature. A transport of xenon towards sample surface has been observed. Transport rate seems to be slow down when increasing sintering temperature. The composition of initial powder and the crystallographic orientation of each considered grain also influence xenon thermal behavior. Xenon release has been correlated with material oxidation during annealing. Xenon bubbles were observed. Their size is proportional with xenon concentration and increases with annealing temperature. Several mechanisms which could explain Xe intragranular mobility in TiN are proposed. In addition with experiments, very low Xe solubility in TiN has been confirmed by ab initio calculations. So, bi-vacancies were found to be the most favoured Xe incorporation sites in this material. (author)

Increased charge storage capacity of titanium nitride electrodes by deposition of boron-doped nanocrystalline diamond films

DEFF Research Database (Denmark)

Meijs, Suzan; McDonald, Matthew; Sørensen, Søren

2015-01-01

The aim of this study was to investigate the feasibility of depositing a thin layer of boron-doped nanocrystalline diamond (B-NCD) on titanium nitride (TiN) coated electrodes and the effect this has on charge injection properties. The charge storage capacity increased by applying the B-NCD film...

Theoretical study of the elastic properties of titanium nitride

Institute of Scientific and Technical Information of China (English)

Jingdong CHEN; Yinglu ZHAO; Benhai YU; Chunlei WANG; Deheng SHI

2009-01-01

The equilibrium lattice parameter, relative volume V/Vo, elastic constants Cij, and bulk modulus of titanium nitride are successfully obtained using the ab initio plane-wave pseudopotential (PW-PP) method within the framework of density functional theory. The quasi-harmonic Debye model, using a set of total energy vs molar volume obtained with the PW-PP method, is applied to the study of the elastic properties and vibrational effects. We analyze the relationship between the bulk modulus and temperature up to 2000 K and obtain the relationship between bulk modulus B and pressure at different temperatures. It is found that the bulk modulus B increases monotonously with increasing pressure and decreases with increasing temperature. Moreover, the Debye temperature is determined from the non-equilibrium Gibbs func-tions.

Diffusion, convection, and solidification in cw-mode free electron laser nitrided titanium

International Nuclear Information System (INIS)

Hoeche, Daniel; Mueller, Sven; Shinn, Michelle; Schaaf, Peter

2009-01-01

Titanium sheets were irradiated by free electron laser radiation in cw mode in pure nitrogen. Due to the interaction, nitrogen diffusion occurs and titanium nitride was synthesized in the tracks. Overlapping tracks have been utilized to create coatings in order to improve the tribological properties of the sheets. Caused by the local heating and the spatial dimension of the melt pool, convection effects were observed and related to the track properties. Stress, hardness, and nitrogen content were investigated with x-ray diffraction, nanoindention, and resonant nuclear reaction analysis. The measured results were correlated with the scan parameters, especially to the lateral track shift. Cross section micrographs were prepared and investigated by means of scanning electron microscopy. They show the solidification behavior, phase formation, and the nitrogen distribution. The experiments give an insight into the possibilities of materials processing using such a unique heat source.

Diffusion, convection, and solidification in cw-mode free electron laser nitrided titanium

Science.gov (United States)

Höche, Daniel; Shinn, Michelle; Müller, Sven; Schaaf, Peter

2009-04-01

Titanium sheets were irradiated by free electron laser radiation in cw mode in pure nitrogen. Due to the interaction, nitrogen diffusion occurs and titanium nitride was synthesized in the tracks. Overlapping tracks have been utilized to create coatings in order to improve the tribological properties of the sheets. Caused by the local heating and the spatial dimension of the melt pool, convection effects were observed and related to the track properties. Stress, hardness, and nitrogen content were investigated with x-ray diffraction, nanoindention, and resonant nuclear reaction analysis. The measured results were correlated with the scan parameters, especially to the lateral track shift. Cross section micrographs were prepared and investigated by means of scanning electron microscopy. They show the solidification behavior, phase formation, and the nitrogen distribution. The experiments give an insight into the possibilities of materials processing using such a unique heat source.

Functional nanostructured titanium nitride films obtained by sputtering magnetron

International Nuclear Information System (INIS)

Sanchez, O.; Hernandez-Velez, M.; Navas, D.; Auger, M.A.; Baldonedo, J.L.; Sanz, R.; Pirota, K.R.; Vazquez, M.

2006-01-01

Development of new methods in the formation of hollow structures, in particular, nanotubes and nanocages are currently generating a great interest as a consequence of the growing relevance of these nanostructures on many technological fields, ranging from optoelectronics to biotechnology. In this work, we report the formation of titanium nitride (TiN) nanotubes and nanohills via reactive sputtering magnetron processes. Anodic Alumina Membranes (AAM) were used as template substrates to grow the TiN nanostructures. The AAM were obtained through electrochemical anodization processes by using oxalic acid solutions as electrolytes. The nanotubes were produced at temperatures below 100 deg. C, and using a pure titanium (99.995%) sputtering target and nitrogen as reactive gas. The obtained TiN thin films showed surface morphologies adjusted to pore diameter and interpore distance of the substrates, as well as ordered arrays of nanotubes or nanohills depending on the sputtering and template conditions. High Resolution Scanning Electron Microscopy (HRSEM) was used to elucidate both the surface order and morphology of the different grown nanostructures. The crystalline structure of the samples was examined using X-ray Diffraction (XRD) patterns and their qualitative chemical composition by using X-ray Energy Dispersive Spectroscopy (XEDS) in a scanning electron microscopy

Differences in proliferation, differentiation, and cytokine production by bone cells seeded on titanium-nitride and cobalt-chromium-molybdenum surfaces

NARCIS (Netherlands)

van Hove, R.P.; Nolte, P.A.; Semeins, C.M.; Klein-Nulend, J.

2013-01-01

Titanium-nitride coating is used to improve cobalt-chromium-molybdenum implant survival in total knee arthroplasty, but its effect on osteoconduction is unknown. Chromium and cobalt ions negatively affect the growth and metabolism of cultured osteoblasts while enhancing osteoclastogenic cytokine

Process for producing silicon nitride based articles of high fracture toughness and strength

Science.gov (United States)

Huckabee, M.; Buljan, S.T.; Neil, J.T.

1991-09-10

A process for producing a silicon nitride-based article of improved fracture toughness and strength is disclosed. The process involves densifying to at least 98% of theoretical density a mixture including (a) a bimodal silicon nitride powder blend consisting essentially of about 10-30% by weight of a first silicon nitride powder of an average particle size of about 0.2 [mu]m and a surface area of about 8-12 m[sup 2]/g, and about 70-90% by weight of a second silicon nitride powder of an average particle size of about 0.4-0.6 [mu]m and a surface area of about 2-4 m[sup 2]/g, (b) about 10-50 percent by volume, based on the volume of the densified article, of refractory whiskers or fibers having an aspect ratio of about 3-150 and having an equivalent diameter selected to produce in the densified article an equivalent diameter ratio of the whiskers or fibers to grains of silicon nitride of greater than 1.0, and (c) an effective amount of a suitable oxide densification aid. Optionally, the mixture may be blended with a binder and injection molded to form a green body, which then may be densified by, for example, hot isostatic pressing.

DEVELOPMENT OF TITANIUM NITRIDE COATING FOR SNS RING VACUUM CHAMBERS

International Nuclear Information System (INIS)

HE, P.; HSEUH, H.C.; MAPES, M.; TODD, R.; WEISS, D.

2001-01-01

The inner surface of the ring vacuum chambers of the US Spallation Neutron Source (SNS) will be coated with ∼100 nm of Titanium Nitride (TiN). This is to minimize the secondary electron yield (SEY) from the chamber wall, and thus avoid the so-called e-p instability caused by electron multipacting as observed in a few high-intensity proton storage rings. Both DC sputtering and DC-magnetron sputtering were conducted in a test chamber of relevant geometry to SNS ring vacuum chambers. Auger Electron Spectroscopy (AES) and Rutherford Back Scattering (RBS) were used to analyze the coatings for thickness, stoichiometry and impurity. Excellent results were obtained with magnetron sputtering. The development of the parameters for the coating process and the surface analysis results are presented

Anomalous response of superconducting titanium nitride resonators to terahertz radiation

International Nuclear Information System (INIS)

Bueno, J.; Baselmans, J. J. A; Coumou, P. C. J. J.; Zheng, G.; Visser, P. J. de; Klapwijk, T. M.; Driessen, E. F. C.; Doyle, S.

2014-01-01

We present an experimental study of kinetic inductance detectors (KIDs) fabricated of atomic layer deposited TiN films and characterized at radiation frequencies of 350 GHz. The responsivity to radiation is measured and found to increase with the increase in radiation powers, opposite to what is expected from theory and observed for hybrid niobium titanium nitride/aluminium (NbTiN/Al) and all-aluminium (all-Al) KIDs. The noise is found to be independent of the level of the radiation power. The noise equivalent power improves with higher radiation powers, also opposite to what is observed and well understood for hybrid NbTiN/Al and all-Al KIDs. We suggest that an inhomogeneous state of these disordered superconductors should be used to explain these observations

Anomalous response of superconducting titanium nitride resonators to terahertz radiation

Energy Technology Data Exchange (ETDEWEB)

Bueno, J., E-mail: j.bueno@sron.nl; Baselmans, J. J. A [SRON, Netherlands Institute of Space Research, Utrecht (Netherlands); Coumou, P. C. J. J.; Zheng, G. [Kavli Institute of Nanoscience, Delft University of Technology, Delft (Netherlands); Visser, P. J. de [SRON, Netherlands Institute of Space Research, Utrecht (Netherlands); Kavli Institute of Nanoscience, Delft University of Technology, Delft (Netherlands); Klapwijk, T. M. [Kavli Institute of Nanoscience, Delft University of Technology, Delft (Netherlands); Physics Department, Moscow State Pedagogical University, 119991 Moscow (Russian Federation); Driessen, E. F. C. [Université Grenoble Alpes, INAC-SPSMS, F-38000 Grenoble (France); CEA, INAC-SPSMS, F-38000 Grenoble (France); Doyle, S. [Cardiff University, School of Physics and Astronomy, Queens Buildings, Cardiff CF24 3AA (United Kingdom)

2014-11-10

We present an experimental study of kinetic inductance detectors (KIDs) fabricated of atomic layer deposited TiN films and characterized at radiation frequencies of 350 GHz. The responsivity to radiation is measured and found to increase with the increase in radiation powers, opposite to what is expected from theory and observed for hybrid niobium titanium nitride/aluminium (NbTiN/Al) and all-aluminium (all-Al) KIDs. The noise is found to be independent of the level of the radiation power. The noise equivalent power improves with higher radiation powers, also opposite to what is observed and well understood for hybrid NbTiN/Al and all-Al KIDs. We suggest that an inhomogeneous state of these disordered superconductors should be used to explain these observations.

NASA GSFC Tin Whisker Homepage http://nepp.nasa.gov/whisker

Science.gov (United States)

Shaw, Harry

2000-01-01

The NASA GSFC Tin Whisker Homepage provides general information and GSFC Code 562 experimentation results regarding the well known phenomenon of tin whisker formation from pure tin plated substrates. The objective of this www site is to provide a central repository for information pertaining to this phenomenon and to provide status of the GSFC experiments to understand the behavior of tin whiskers in space environments. The Tin Whisker www site is produced by Code 562. This www site does not provide information pertaining to patented or proprietary information. All of the information contained in this www site is at the level of that produced by industry and university researchers and is published at international conferences.

High quality superconducting titanium nitride thin film growth using infrared pulsed laser deposition

Science.gov (United States)

Torgovkin, A.; Chaudhuri, S.; Ruhtinas, A.; Lahtinen, M.; Sajavaara, T.; Maasilta, I. J.

2018-05-01

Superconducting titanium nitride (TiN) thin films were deposited on magnesium oxide, sapphire and silicon nitride substrates at 700 °C, using a pulsed laser deposition (PLD) technique, where infrared (1064 nm) pulses from a solid-state laser were used for the ablation from a titanium target in a nitrogen atmosphere. Structural studies performed with x-ray diffraction showed the best epitaxial crystallinity for films deposited on MgO. In the best films, superconducting transition temperatures, T C, as high as 4.8 K were observed, higher than in most previous superconducting TiN thin films deposited with reactive sputtering. A room temperature resistivity down to ∼17 μΩ cm and residual resistivity ratio up to 3 were observed in the best films, approaching reported single crystal film values, demonstrating that PLD is a good alternative to reactive sputtering for superconducting TiN film deposition. For less than ideal samples, the suppression of the film properties were correlated mostly with the unintended incorporation of oxygen (5–10 at%) in the film, and for high oxygen content films, vacuum annealing was also shown to increase the T C. On the other hand, superconducting properties were surprisingly insensitive to the nitrogen content, with high quality films achieved even in the highly nitrogen rich, Ti:N = 40/60 limit. Measures to limit oxygen exposure during deposition must be taken to guarantee the best superconducting film properties, a fact that needs to be taken into account with other deposition methods, as well.

Pulsed Laser Deposition Processing of Improved Titanium Nitride Coatings for Implant Applications

Science.gov (United States)

Haywood, Talisha M.

Recently surface coating technology has attracted considerable attention of researchers to develop novel coatings with enhanced functional properties such as hardness, biocompatibility, wear and corrosion resistance for medical devices and surgical tools. The materials currently being used for surgical implants include predominantly stainless steel (316L), cobalt chromium (Co-Cr), titanium and its alloys. Some of the limitations of these implants include improper mechanical properties, corrosion resistance, cytotoxicity and bonding with bone. One of the ways to improve the performance and biocompatibility of these implants is to coat their surfaces with biocompatible materials. Among the various coating materials, titanium nitride (TiN) shows excellent mechanical properties, corrosion resistance and low cytotoxicity. In the present work, a systematic study of pulsed laser ablation processing of TiN coatings was conducted. TiN thin film coatings were grown on commercially pure titanium (Ti) and stainless steel (316L) substrates at different substrate temperatures and different nitrogen partial pressures using the pulsed laser deposition (PLD) technique. Microstructural, surface, mechanical, chemical, corrosion and biological analysis techniques were applied to characterize the TiN thin film coatings. The PLD processed TiN thin film coatings showed improvements in mechanical strength, corrosion resistance and biocompatibility when compared to the bare substrates. The enhanced performance properties of the TiN thin film coatings were a result of the changing and varying of the deposition parameters.

Structure and phase composition of titanium nitride coating on austenitic steel

International Nuclear Information System (INIS)

Dubovitskaya, N.V.; Kolenchenko, L.D.; Larikov, L.N.

1989-01-01

Structure and phase composition of titanium nitride coating deposited on 08Kh18N10T steel substrate using ''Bulat'' device are studied. Use of complex investigation methods permitted despite small coating thickness (1μm) to aquire information on hardness, porosity, to study phase composition in all coating thickness. The surface layer (∼0.1 μm) consists of ε-Ti 2 N, TiN 0.6 , TiC 0.35 , that is formed with carbon participation from oil vacuum. In more deeper layers beside ε-Ti 2 N TiC 0.14 N 0.77 is present. Effect of carbon diffusion from substrate to forming coating is stated. Gradient of element concentrations in the substrate-coating interface causes recrystallization of austenite

Thermochemical stability of zirconia-titanium nitride as mixed ionic-electronic composites

DEFF Research Database (Denmark)

Silva, P. S. M.; Esposito, V.; Marani, D.

2018-01-01

Dense zirconia (8% molar yttria-stabilized ZrO2)-titanium nitride (TiN) composites are fabricated to obtain mixed ionic-electronic conducting ceramic systems with high degree of electronic and thermal conductivity. The composites are consolidated by spark plasma sintering (SPS), starting from pure...... the composites, high electrical conductivity is attained. Samples exhibit metallic behavior, showing an unexpected percolation of TiN in the YSZ matrix for volume fraction ≤ 25 wt% (27 vol%). Chemical degradation and electrical properties of the compounds were monitored under oxidative (air) and inert (Ar...... transport properties of the composite can be tuned by both the relative volume fraction of phases and controlled oxidative treatments. Adjusting such parameters different electric behaviors were observed ranging from predominant electronic conductors, to temperature-independent resistivity...

Power mixture and green body for producing silicon nitride base articles of high fracture toughness and strength

Science.gov (United States)

Huckabee, M.L.; Buljan, S.T.; Neil, J.T.

1991-09-17

A powder mixture and a green body for producing a silicon nitride-based article of improved fracture toughness and strength are disclosed. The powder mixture includes (a) a bimodal silicon nitride powder blend consisting essentially of about 10-30% by weight of a first silicon nitride powder of an average particle size of about 0.2 [mu]m and a surface area of about 8-12m[sup 2]g, and about 70-90% by weight of a second silicon nitride powder of an average particle size of about 0.4-0.6 [mu]m and a surface area of about 2-4 m[sup 2]/g, (b) about 10-50 percent by volume, based on the volume of the densified article, of refractory whiskers or fibers having an aspect ratio of about 3-150 and having an equivalent diameter selected to produce in the densified article an equivalent diameter ratio of the whiskers or fibers to grains of silicon nitride of greater than 1.0, and (c) an effective amount of a suitable oxide densification aid. The green body is formed from the powder mixture, an effective amount of a suitable oxide densification aid, and an effective amount of a suitable organic binder. No Drawings

NASA Goddard Space Flight Center Tin Whisker (and Other Metal Whisker) Homepage

Science.gov (United States)

Brusse, Jay; Sampson, Mike; Leidecker, Henning; Kadesch, Jong

2004-01-01

This website provides information about tin whiskers and related research. The independent research performed during the past 50+ years is so vast that it is impractical to cover all aspects of tin whiskers in this one resource. Therefore, the absence of information in this website about a particular aspect of tin whiskers should NOT be construed as evidence of absence.

Comparative study of titanium carbide and nitride coatings grown by cathodic vacuum arc technique

International Nuclear Information System (INIS)

Devia, D.M.; Restrepo-Parra, E.; Arango, P.J.

2011-01-01

Titanium nitride (TiN), titanium carbide (TiC) thin films and TiC/TiN bilayers have been deposited on AISI 304 stainless steel substrates by plasma assisted physical vapor deposition technique - reactive pulsed vacuum arc method. The coatings were characterized in terms of crystalline structure, microstructure and chemical nature by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. Tribological behavior was investigated using ball on disc technique. The average coefficient of friction was measured, showing lower values for the TiN/TiC bilayer. Dynamic wear curves were performed for each coating, observing a better wear resistance for TiN/TiC bilayers, compared to TiN and TiC monolayers. On the other hand, the TiCN formation in the TiN/TiC bilayer was observed, being attributed to the interdiffusion between TiN and TiC at the interface. Moreover, the substrate temperature influence was analysing observing a good behavior at T S = 115 °C.

The Mechanical and Tribology Properties of Sputtered Titanium Aluminum Nitride Coating on the Tungsten Carbide Insert Tool in the Dry Turning of Tool Steel

Directory of Open Access Journals (Sweden)

Esmar Budi

2015-02-01

Full Text Available The effect of the sputtering parameters on the mechanical tribology properties of Titanium Aluminum Nitride coating on the tungsten cabide insert tool in the dry turning of tool steel has been investigated. The coating was deposited using a Direct Current magnetron sputtering system with various substrate biases (-79 to -221 V and nitrogen flow rates (30 to 72 sccm. The dry turning test was carried out on a Computer Numeric Code machine using an optimum cutting parameter setting. The results show that the lowest flank wear (~0.4 mm was achieved using a Titanium Aluminum Nitride-coated tool that was deposited at a high substrate bias (-200 V and a high nitrogen flow rate (70 sccm. The lowest flank wear was attributed to high coating hardness.

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

Structure and hemocompatibility of nanocrystalline titanium nitride produced under glow-discharge conditions

Science.gov (United States)

Sowińska, Agnieszka; Czarnowska, Elżbieta; Tarnowski, Michał; Witkowska, Justyna; Wierzchoń, Tadeusz

2018-04-01

Significant efforts are being made towards developing novel antithrombotic materials. The purpose of the presented study was to characterize two variants of nitrided surface layers produced on alloy Ti-6Al-4V in different areas of low-temperature plasma - at the plasma potential (TiNp) or at the cathode potential (TiNc). The layers were characterized in terms of their microstructure, surface topography and wettability, and platelet response to the environment of different pH. The produced layers were of the TiN + Ti2N + αTiN-type, but the layer produced at the plasma potential was thinner, smoother and had lower surface free energy compared with that produced at the cathode potential. Biological evaluation demonstrated more fibrinogen buildup, less platelet adhesion and aggregation, and fewer strongly activated platelets on the TiNp surface compared with those parameters on the TiNc surface and on the titanium alloy in its initial state. Interestingly, both surface types were significantly resistant to fibrinogen adsorption and platelet adhesion in the environment of lower pH. In conclusion, the nitrided surface layer produced at the plasma potential is a promising material and this basic information is critical for further development of hemocompatible materials.

High aspect ratio titanium nitride trench structures as plasmonic biosensor

DEFF Research Database (Denmark)

Shkondin, Evgeniy; Repän, Taavi; Takayama, Osamu

2017-01-01

High aspect ratio titanium nitride (TiN) grating structures are fabricated by the combination of deep reactive ion etching (DRIE) and atomic layer deposition (ALD) techniques. TiN is deposited at 500 ◦C on a silicon trench template. Silicon between vertical TiN layers is selectively etched...... to fabricate the high aspect ratio TiN trenches with the pitch of 400 nm and height of around 2.7 µm. Dielectric functions of TiN films with different thicknesses of 18 - 105 nm and post-annealing temperatures of 700 - 900 ◦C are characterized by an ellipsometer. We found that the highest annealing temperature...... of 900 ◦C gives the most pronounced plasmonic behavior with the highest plasma frequency, ωp = 2.53 eV (λp = 490 nm). Such high aspect ratio trench structures function as a plasmonic grating sensor that supports the Rayleigh-Woods anomalies (RWAs), enabling the measurement of changes in the refractive...

Mitigating tin whisker risks theory and practice

CERN Document Server

Handwerker, Carol A; Bath, Jasbir

2016-01-01

Discusses the growth mechanisms of tin whiskers and the effective mitigation strategies necessary to reduce whisker growth risks. This book covers key tin whisker topics, ranging from fundamental science to practical mitigation strategies. The text begins with a review of the characteristic properties of local microstructures around whisker and hillock grains to identify why these particular grains and locations become predisposed to forming whiskers and hillocks. The book discusses the basic properties of tin-based alloy finishes and the effects of various alloying elements on whisker formation, with a focus on potential mechanisms for whisker suppression or enhancement for each element. Tin whisker risk mitigation strategies for each tier of the supply chain for high reliability electronic systems are also described.

Metal Whiskers: A Discussion of Risks and Mitigation

Science.gov (United States)

2010-11-30

efforts to investigate – Chromate conversion finishes DO NOT appear to stop whisker formation [4] S. Arnold, "Repressing the Growth of Tin Whiskers...November 30, 2010 Metal Whiskers 10 Examples of Metal Whiskers Zinc-Plated Steel Bus Rail with Yellow Chromate Conversion Finish Zinc whiskers grew...Metal Whiskers 11 Examples of Metal Whiskers Tin-Plated D-Sub Connector Shell Connector Advertised as “RoHS Compliant” November 30, 2010 Metal

Hidroxyapatite Coating on CoCrMo Alloy Titanium Nitride Coated Using Biomimetic Method

International Nuclear Information System (INIS)

Charlena; Sukaryo, S.G.; Fajar, M.

2016-01-01

Bone implants is a way to cure broken bones which is being developed. The implants can be made of metals, ceramics and polymers. Metallic materials commonly used are titanium (Ti), stainless steel, and metal alloys. This study used Co-based alloys, i.e. CoCrMo coated with titanium nitride (TiN) which was then coated on hidroxyapatite (HAp). The HAp coating on the surface of CoCrMo alloy was done by biomimetic methods, first by soaking the metal alloys in simulated body fluid (SBF) solution for 18, 24, and 36 hours. The immersion in the SBF solution produced white coat on the surface of the metal alloy. The layers formed were analyzed by scanning electron microscope (SEM) and characterized by x-ray diffractometer (XRD). Based on the SEM results of 36 hours treatment, the morphology of apatite crystal formed fine grains. According to XRD result, there were HAp peaks at angles 2θ 31.86, 32.25, dan 39.48. However, there were also CaCO 3 peaks at angles 2θ 29.46, 36.04, and 46.79. It indicated the pure HAp is not yet formed. (paper)

Hidroxyapatite Coating on CoCrMo Alloy Titanium Nitride Coated Using Biomimetic Method

Science.gov (United States)

Charlena; Sukaryo, S. G.; Fajar, M.

2016-11-01

Bone implants is a way to cure broken bones which is being developed. The implants can be made of metals, ceramics and polymers. Metallic materials commonly used are titanium (Ti), stainless steel, and metal alloys. This study used Co-based alloys, i.e. CoCrMo coated with titanium nitride (TiN) which was then coated on hidroxyapatite (HAp). The HAp coating on the surface of CoCrMo alloy was done by biomimetic methods, first by soaking the metal alloys in simulated body fluid (SBF) solution for 18, 24, and 36 hours. The immersion in the SBF solution produced white coat on the surface of the metal alloy. The layers formed were analyzed by scanning electron microscope (SEM) and characterized by x-ray diffractometer (XRD). Based on the SEM results of 36 hours treatment, the morphology of apatite crystal formed fine grains. According to XRD result, there were HAp peaks at angles 2θ 31.86, 32.25, dan 39.48. However, there were also CaCO3 peaks at angles 2θ 29.46, 36.04, and 46.79. It indicated the pure HAp is not yet formed.

Nano-structure and tribological properties of B+ and Ti+ co-implanted silicon nitride

International Nuclear Information System (INIS)

Nakamura, Naoki; Noda, Katsutoshi; Yamauchi, Yukihiko

2005-01-01

Silicon nitride ceramics have been co-implanted with boron and titanium ions at a fluence of 2 x 10 17 ions/cm 2 and an energy of 200 keV. TEM results indicated that the boron and titanium-implanted layers were amorphized separately and titanium nitride nano-crystallites were formed in the titanium-implanted layer. XPS results indicated that the implantation profile varied a little depending on the ion implantation sequence of boron and titanium ions, with the boron implantation peak shifting to a shallower position when implanted after Ti + -implantation. Wear tests of these ion-implanted materials were carried out using a block-on-ring wear tester under non-lubricated conditions against commercially available silicon nitride materials. The specific wear rate was reduced by ion implantation and showed that the specific wear rate of Ti + -implanted sample was the lowest, followed by B + , Ti + co-implanted and B + -implanted samples

Cellulose whisker/epoxy resin nanocomposites.

Science.gov (United States)

Tang, Liming; Weder, Christoph

2010-04-01

New nanocomposites composed of cellulose nanofibers or "whiskers" and an epoxy resin were prepared. Cellulose whiskers with aspect ratios of approximately 10 and approximately 84 were isolated from cotton and sea animals called tunicates, respectively. Suspensions of these whiskers in dimethylformamide were combined with an oligomeric difunctional diglycidyl ether of bisphenol A with an epoxide equivalent weight of 185-192 and a diethyl toluenediamine-based curing agent. Thin films were produced by casting these mixtures and subsequent curing. The whisker content was systematically varied between 4 and 24% v/v. Electron microscopy studies suggest that the whiskers are evenly dispersed within the epoxy matrix. Dynamic mechanical thermoanalysis revealed that the glass transition temperature (T(g)) of the materials was not significantly influenced by the incorporation of the cellulose filler. Between room temperature and 150 degrees C, i.e., below T(g), the tensile storage moduli (E') of the nanocomposites increased modestly, for example from 1.6 GPa for the neat polymer to 4.9 and 3.6 GPa for nanocomposites comprising 16% v/v tunicate or cotton whiskers. The relative reinforcement was more significant at 185 degrees C (i.e., above T(g)), where E' was increased from approximately 16 MPa (neat polymer) to approximately 1.6 GPa (tunicate) or approximately 215 MPa (cotton). The mechanical properties of the new materials are well-described by the percolation model and are the result of the formation of a percolating whisker network in which stress transfer is facilitated by strong interactions between the whiskers.

Tapered whiskers are required for active tactile sensation.

Science.gov (United States)

Hires, Samuel Andrew; Pammer, Lorenz; Svoboda, Karel; Golomb, David

2013-11-19

Many mammals forage and burrow in dark constrained spaces. Touch through facial whiskers is important during these activities, but the close quarters makes whisker deployment challenging. The diverse shapes of facial whiskers reflect distinct ecological niches. Rodent whiskers are conical, often with a remarkably linear taper. Here we use theoretical and experimental methods to analyze interactions of mouse whiskers with objects. When pushed into objects, conical whiskers suddenly slip at a critical angle. In contrast, cylindrical whiskers do not slip for biologically plausible movements. Conical whiskers sweep across objects and textures in characteristic sequences of brief sticks and slips, which provide information about the tactile world. In contrast, cylindrical whiskers stick and remain stuck, even when sweeping across fine textures. Thus the conical whisker structure is adaptive for sensor mobility in constrained environments and in feature extraction during active haptic exploration of objects and surfaces. DOI: http://dx.doi.org/10.7554/eLife.01350.001.

Different shape normal metal interlayers between niobium based SIS junctions and niobium titanium nitride leads and their influence on the electron temperature

International Nuclear Information System (INIS)

Selig, S; Westig, M P; Jacobs, K; Honingh, C E

2014-01-01

In this paper we demonstrate the reduction of heating in a niobium superconductor-insulator-superconductor (SIS) junction with aluminum-oxide tunnel barrier embedded in a niobium-titanium-nitride circuit. Nonequilibrium quasiparticles which are created due to the Andreev trap at the interface between the niobium and the niobium-titanium-nitride layers are relaxed by inserting a normal-metal conductor of gold between these two layers. In an earlier work we explained the observed relaxation of nonequilibrium quasiparticles due to the geometrically assisted cooling effect. In this paper we investigate this cooling effect in dependence of the normal-metal layer shape and size. We expect that an adapted normal-metal layer is necessary for implementation in practical terahertz SIS heterodyne mixer circuits. We observe in DC-measurements of a large number of devices a clear relation between the volume of the gold layer and the effective electron temperature in the device. Our central finding is that the shape of the gold layer does not influence the cooling provided that the volume is sufficient.

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

Production and characterization of a novel carbon nanotube/titanium nitride nanocomposite

Science.gov (United States)

Baddour, Carole Emilie; Das, Kaushik; Vengallatore, Srikar; Meunier, Jean-Luc

2016-12-01

A novel titanium nitride (TiN)/carbon nanotube (CNT) nanocomposite is produced with the purpose to mechanically, structurally and chemically stabilize a ‘felt-like’ CNT growth structure. The CNTs are grown on stainless steel (SS) 304 by chemical vapor deposition using the direct growth method previously developed, which does not require the use of an additional catalyst precursor. The TiN coating is achieved by physical vapor deposition and is shown here to generate a nanocomposite with a porous three-dimensional architecture. The contact stiffness is evaluated using nanoindentation, and wetting properties of the TiN/CNT nanocomposites are determined from contact angle measurements. An increase in contact stiffness and effective elastic modulus with TiN coating time was observed. The TiN coating on the non-wetting CNT felt results in a wetting nanocomposite surface. The wetting property is found to be a function of the TiN coating thickness on the CNT structure.

Non-carbon titanium cobalt nitride nanotubes supported platinum catalyst with high activity and durability for methanol oxidation reaction

Science.gov (United States)

Chen, Xiaoxiang; Li, Wuyi; Pan, Zhanchang; Xu, Yanbin; Liu, Gen; Hu, Guanghui; Wu, Shoukun; Li, Jinghong; Chen, Chun; Lin, Yingsheng

2018-05-01

Titanium cobalt nitride nanotubes (Ti0.95Co0.05N NTs) hybrid support, a novel robust non-carbon support material prepared by solvothermal and post-nitriding processes, is further decorated with Pt nanoparticles for the electrooxidation of methanol. The catalyst is characterized by X-ray diffraction (XRD), nitrogen adsorption/desorption, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and electrochemical measurements. The morphology, structure and composition of the synthesized Ti0.95Co0.05N NTs suggest that the nanotube wall is porous and consists of homogeneous cohesively attached nitrides nanocube particles. Notable, Ti0.95Co0.05N NTs supported Pt catalyst exhibits significantly improved catalytic activity and durability for methanol electrooxidation compared with the conventional JM Pt/C catalyst. The experimental data indicate that enhanced catalytic activity and stability of Pt/Ti0.95Co0.05N NTs towards methanol electrooxidation might be mainly attributed to the tubular nanostructures and synergistic effect introduced by the Co doping. Both of them are playing an important role in improving the activity and durability of the Ti0.95Co0.05N NTs catalyst.

Erosion resistance of composite materials on titanium, zirconium and aluminium nitride base under the electron beam effect

International Nuclear Information System (INIS)

Verkhoturov, A.D.; Kuzenkova, M.A.; Slutskin, M.G.; Kravchuk, L.A.

1977-01-01

Erosion resistance of composites based on nitrides of titanium, zirconium and aluminium to spark and electron beam processing has been studied. The erosion resistance in spark processing is shown to depend on specific electric resistance of the alloys. TiN-AlN and ZrN-AlN alloys containing more than 70% AlN (with specific electric resistance more than 10 6 -10 7 ohm/cm) caot be processed by spark method. It is shown that erosion of the composites by an electron beam depends primarily on the rate of evaporation of the components

Performance analysis of nitride alternative plasmonic materials for localized surface plasmon applications

DEFF Research Database (Denmark)

Guler, U.; Naik, G. V.; Boltasseva, Alexandra

2012-01-01

. Titanium nitride and zirconium nitride, which were recently suggested as alternative plasmonic materials in the visible and near-infrared ranges, are compared to the performance of gold. In contrast to the results from quasistatic methods, both nitride materials are very good alternatives to the usual...

Conducting metal oxide and metal nitride nanoparticles

Science.gov (United States)

DiSalvo, Jr., Francis J.; Subban, Chinmayee V.

2017-12-26

Conducting metal oxide and nitride nanoparticles that can be used in fuel cell applications. The metal oxide nanoparticles are comprised of for example, titanium, niobium, tantalum, tungsten and combinations thereof. The metal nitride nanoparticles are comprised of, for example, titanium, niobium, tantalum, tungsten, zirconium, and combinations thereof. The nanoparticles can be sintered to provide conducting porous agglomerates of the nanoparticles which can be used as a catalyst support in fuel cell applications. Further, platinum nanoparticles, for example, can be deposited on the agglomerates to provide a material that can be used as both an anode and a cathode catalyst support in a fuel cell.

Electric field stimulated growth of Zn whiskers

Energy Technology Data Exchange (ETDEWEB)

Niraula, D.; McCulloch, J.; Irving, R.; Karpov, V. G. [Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (United States); Warrell, G. R.; Shvydka, Diana, E-mail: diana.shvydka@utoledo.edu [Department of Radiation Oncology, University of Toledo Health Science Campus, Toledo, Ohio 43614 (United States)

2016-07-15

We have investigated the impact of strong (∼10{sup 4} V/cm) electric fields on the development of Zn whiskers. The original samples, with considerable whisker infestation were cut from Zn-coated steel floors and then exposed to electric fields stresses for 10-20 hours at room temperature. We used various electric field sources, from charges accumulated in samples irradiated by: (1) the electron beam of a scanning electron microscope (SEM), (2) the electron beam of a medical linear accelerator, and (3) the ion beam of a linear accelerator; we also used (4) the electric field produced by a Van der Graaf generator. In all cases, the exposed samples exhibited a considerable (tens of percent) increase in whiskers concentration compared to the control sample. The acceleration factor defined as the ratio of the measured whisker growth rate over that in zero field, was estimated to approach several hundred. The statistics of lengths of e-beam induced whiskers was found to follow the log-normal distribution known previously for metal whiskers. The observed accelerated whisker growth is attributed to electrostatic effects. These results offer promise for establishing whisker-related accelerated life testing protocols.

Electric field stimulated growth of Zn whiskers

Science.gov (United States)

Niraula, D.; McCulloch, J.; Warrell, G. R.; Irving, R.; Karpov, V. G.; Shvydka, Diana

2016-07-01

We have investigated the impact of strong (˜104 V/cm) electric fields on the development of Zn whiskers. The original samples, with considerable whisker infestation were cut from Zn-coated steel floors and then exposed to electric fields stresses for 10-20 hours at room temperature. We used various electric field sources, from charges accumulated in samples irradiated by: (1) the electron beam of a scanning electron microscope (SEM), (2) the electron beam of a medical linear accelerator, and (3) the ion beam of a linear accelerator; we also used (4) the electric field produced by a Van der Graaf generator. In all cases, the exposed samples exhibited a considerable (tens of percent) increase in whiskers concentration compared to the control sample. The acceleration factor defined as the ratio of the measured whisker growth rate over that in zero field, was estimated to approach several hundred. The statistics of lengths of e-beam induced whiskers was found to follow the log-normal distribution known previously for metal whiskers. The observed accelerated whisker growth is attributed to electrostatic effects. These results offer promise for establishing whisker-related accelerated life testing protocols.

Evaluation of Antibacterial Activity of Titanium Surface Modified by PVD/PACVD Process.

Science.gov (United States)

Ji, Min-Kyung; Lee, Min-Joo; Park, Sang-Won; Lee, Kwangmin; Yun, Kwi-Dug; Kim, Hyun-Seung; Oh, Gye-Jeong; Kim, Ji-Hyun; Lim, Hyun-Pil

2016-02-01

The aim of this study was to evaluate the response of Streptococcus mutans (S. mutans) via crystal violet staining assay on titanium surface modified by physical vapor deposition/plasma assisted chemical vapor deposition process. Specimens were divided into the following three groups: polished titanium (control group), titanium modified by DC magnetron sputtering (group TiN-Ti), and titanium modified by plasma nitriding (group N-Ti). Surface characteristics of specimens were observed by using nanosurface 3D optical profiler and field emission scanning electron microscope. Group TiN-Ti showed TiN layer of 1.2 microm in thickness. Group N-Ti was identified as plasma nitriding with X-ray photoelectron spectroscopy. Roughness average (Ra) of all specimens had values 0.05). Within the process condition of this study, modified titanium surfaces by DC magnetron sputtering and plasma nitriding did not influence the adhesion of S. mutans.

Temperature-dependent transformation from whisker- to nanoparticle-strengthened composite interface in the Al2O3/Ag-based alloy system and mechanical properties of the joints

International Nuclear Information System (INIS)

Wang, Yifeng; Cao, Jian; Wang, Zhijie; Chen, Zhe; Song, Xiaoguo; Feng, Jicai

2015-01-01

Al 4 B 2 O 9 -whisker-coated Al 2 O 3 ceramics were bonded by AgCu–4.5 wt.%Ti alloy in vacuum. The microstructure of the whisker-coated Al 2 O 3 joints was investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. A continuous (Cu,Al) 3 Ti 3 O layer formed against the alloy at lower bonding temperatures, and a complex transition zone bordering the whiskers was observed, which consisted of Ag nanoparticles, titanium oxides, TiB 2 , (Cu,Al) 3 Ti 3 O nanoparticles and possible Ag 3 Al. As the bonding temperature increased, the Al 2 O 3 /AgCuTi interface was found to transform from whisker- to nanoparticle-strengthened composite region. Bend test results revealed that both the whiskers grown on Al 2 O 3 and the dispersive nanoscale products in the alloy played positive roles in improving the joint properties. The maximum bend strength of the whisker-coated Al 2 O 3 joints was 313 MPa at the bonding temperature of 820 °C. - Highlights: • Al 4 B 2 O 9 -whisker-coated Al 2 O 3 ceramics were bonded by AgCu–4.5 wt.%Ti alloy in vacuum. • Microstructures of whisker-coated Al 2 O 3 joints were investigated in detail. • Both whiskers and the dispersive nanoscale products can improve the joint properties. • The maximum bend strength of the whisker-coated Al 2 O 3 joints was 313 MPa.

The crystallographic growth directions of Sn whiskers

International Nuclear Information System (INIS)

Stein, J.; Welzel, U.; Leineweber, A.; Huegel, W.; Mittemeijer, E.J.

2015-01-01

The growth directions of 55 Sn whiskers, i.e. the crystallographic orientation parallel to the whisker-growth axes, were determined using (i) a focused ion beam microscope for the determination of the physical growth angles of the whiskers with respect to a specimen (reference) coordinate system and (ii) an electron backscatter detector in a scanning electron microscope for the determination of the crystallographic orientation of the whiskers. The Sn whiskers were found to grow preferentially along low-index directions of the β-Sn crystal structure. The experimental findings of this study (and most of the results presented in the literature as well) were explained by applying, in a modified way, the Hartman–Perdok concept of periodic bond chains, i.e. chains of strong bonds running uninterruptedly through the structure, to the Sn whisker-growth phenomenon

Hardness and Elastic Modulus of Titanium Nitride Coatings Prepared by Pirac Method

Science.gov (United States)

Wu, Siyuan; Wu, Shoujun; Zhang, Guoyun; Zhang, Weiguo

In the present work, hardness and elastic modulus of a titanium nitride coatings prepared on Ti6Al4V by powder immersion reaction-assisted coating (PIRAC) are tested and comparatively studied with a physical vapor deposition (PVD) TiN coating. Surface hardness of the PIRAC coatings is about 11GPa, much lower than that of PVD coating of 22GPa. The hardness distribution profile from surface to substrate of the PVD coatings is steeply decreased from ˜22GPa to ˜4.5GPa of the Ti6Al4V substrate. The PIRAC coatings show a gradually decreasing hardness distribution profile. Elastic modulus of the PVD coating is about 426GPa. The PIRAC coatings show adjustable elastic modulus. Elastic modulus of the PIRAC coatings prepared at 750∘C for 24h and that at 800∘C for 8h is about 234 and 293GPa, respectively.

Synthesis of Bi2Sr2CaCu2O8+δ whiskers and cross-whisker intrinsic Josephson junction

International Nuclear Information System (INIS)

Hatano, T.; Takano, Y.; Arisawa, S.; Ishii, A.; Togano, K.; Fukuyo, A.

2001-01-01

A synthesis technique of Bi 2 Sr 2 CaCu 2 O 8+δ single-crystal whiskers was studied. The whiskers were synthesized by heating glassy melt-quenched Bi-Sr-Ca-Cu-O (3:2:2:4 in cationic ratio) plates. The atmospheric condition of the whisker growth, especially oxygen partial pressure and gas flow, was investigated. It was found out that the whisker growth rate shows a maximum at P O2 =2/3 bar. For the crystalline quality of the whiskers, the airtight condition was found to be useful as compared to the conventional oxygen stream condition. The crystalline quality, especially the straightness and morphology of the surface, could be improved by keeping the growing whiskers under the equilibrium P Bi condition. Over 20-mm-long whisker crystals have been successfully synthesized by choosing optimum oxygen partial pressure around the P O2 =2/3 bar in the airtight condition. The growth condition and mechanism of the Bi 2 Sr 2 CaCu 2 O 8+δ whiskers were investigated by an in-situ high-temperature x-ray diffraction analysis and an in-situ high-temperature microscope observation. It was found that the whiskers grow in a partially melted state at a temperature of 10-40 degrees below the melting point. The result obtained demonstrates that Bi 2 Sr 2 CaCu 2 O 8+δ whiskers grow at their bottom by the conventional liquid-phase growth mechanism, as was proposed by Matsubara et al. (author)

Inorganic-whisker-reinforced polymer composites synthesis, properties and applications

CERN Document Server

Sun, Qiuju

2015-01-01

Inorganic-Whisker-Reinforced Polymer Composites: Synthesis, Properties and Applications gives a comprehensive presentation of inorganic microcrystalline fibers, or whiskers, a polymer composite filler. It covers whisker synthesis, surface modification, applications for reinforcing polymer-matrix composites, and analysis of resulting filled polymer composites. It focuses on calcium carbonate whiskers as a primary case study, introducing surface treatment methods for calcium carbonate whiskers and factors that influence them. Along with calcium carbonate, the book discusses potassium titanate and aluminum borate whiskers, which also comprise the new generation of inorganic whiskers. According to research results, composites filled by inorganic whiskers show improved strength, wear-resistance, thermal conductivity, and antistatic properties. It explains the importance of modifying polymer materials for use with inorganic whiskers and describes preparation and evaluation methods of polymers filled with inorganic ...

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

Sn whiskers removed by energy photo flashing

International Nuclear Information System (INIS)

Jiang, N.; Yang, M.; Novak, J.; Igor, P.; Osterman, M.

2012-01-01

Highlights: ► Sn whiskers were sintered by intense light flashing (Photosintering). ► Photosintering can effectively eliminate Sn whiskers. ► Photosintering would not damage electronic devices. ► Photosintering is a very promising approach to improve Sn-based electronic surface termination. - Abstract: Sn whiskers have been known to be the major issue resulting in electronic circuit shorts. In this study, we present a novel energy photo flashing approach (photosintering) to shorten and eliminate Sn whiskers. It has been found that photosintering is very effective to modify and remove Sn whiskers; only a sub-millisecond duration photosintering can amazingly get rid of over 90 vol.% of Sn whiskers. Moreover, this photosintering approach has also been proved to cause no damages to electronic devices, suggesting it is a potentially promising way to improve Sn-based electronic surface termination.

Low-loss and tunable near-zero-epsilon titanium nitride

Science.gov (United States)

Popović, M.; Novaković, M.; Schmidt, E.; Schöppe, P.; Bibić, N.; Ronning, C.; Rakočević, Z.

2017-10-01

Titanium nitride (TiN) has emerged as alternative plasmonic material in the visible and near-infrared spectral range due to its metallic properties. We studied the influence of silver ion implantation (fluence range from 0.5 × 1016-6 × 1016 ions/cm2) on the structural and optical properties of reactively sputtered 260 nm thick TiN films. The columnar structure was partially destroyed by the irradiation and up to 5 at.% of Ag was incorporated into the films within the projected ion range. The formation of cubic Ag nanoparticles with size of 1-2 nm was observed by high resolution transmission electron microscopy and subsequent fast Fourier transform analysis. This presence of Ag within the TiN matrix drastically changes both the real and imaginary component of the dielectric function and provides low optical losses. A Drude Lorentz dielectric analysis based on free electron and oscillator model are carried out to describe the silver influence on the optical behavior of TiN. With increasing ion fluence, the unscreened plasma frequency decreased and broadening increased. The energy, strength and broadening of the interband transitions were studied with respect to the silver ion fluence and correlated with the microstructural changes induced in TiN films.

Spontaneous Formation of Titanium Nitride on the Surface of a Ti Rod Induced by Electro-Discharge-Heat-Treatment in an N2 Atmosphere

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Lee W.H.

2017-06-01

Full Text Available A single pulse of 2.0 to 3.5 kJ of input energy from a 450 mF capacitor was applied to a commercially pure Ti rod in a N2 atmosphere. The surface of the Ti rod transformed from TiO2 into titanium nitride in times as short as 159 msec, providing a bimodal morphology of the cross-section. A much higher value of hardness that was observed at the edge of the cross-section was attributed to nitrogen-induced solid-solution hardening that occurred during the electrical discharge process. The activation energy (Ea for the diffusion process was estimated to be approximately 86.9 kJ/mol. Results show that the electrical discharge process is a possible potential method for the nitriding of Ti; advantages include a short processing time and control of the nitrided layer without dimensional changes.

Highly catalytic and stabilized titanium nitride nanowire array-decorated graphite felt electrodes for all vanadium redox flow batteries

Science.gov (United States)

Wei, L.; Zhao, T. S.; Zeng, L.; Zeng, Y. K.; Jiang, H. R.

2017-02-01

In this work, we prepare a highly catalytic and stabilized titanium nitride (TiN) nanowire array-decorated graphite felt electrode for all vanadium redox flow batteries (VRFBs). Free-standing TiN nanowires are synthesized by a two-step process, in which TiO2 nanowires are first grown onto the surface of graphite felt via a seed-assisted hydrothermal method and then converted to TiN through nitridation reaction. When applied to VRFBs, the prepared electrode enables the electrolyte utilization and energy efficiency to be 73.9% and 77.4% at a high current density of 300 mA cm-2, which are correspondingly 43.3% and 15.4% higher than that of battery assembled with a pristine electrode. More impressively, the present battery exhibits good stability and high capacity retention during the cycle test. The superior performance is ascribed to the significant improvement in the electrochemical kinetics and enlarged active sites toward V3+/V2+ redox reaction.

Research on SiC Whisker Prepared by H-PSO

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WANG Yao

2017-10-01

Full Text Available SiC whiskers were prepared on the matrix of graphite by using high hydrogenous silicone oil(PSO as raw material. The effect of surface conditions of graphite and heating temperature on the growth of SiC whisker was mainly studied in this paper. The main factor which affects the nucleation and growth of SiC whisker is the heating temperature, with the heating temperature rising, the production of SiC whisker increases. The surface condition of graphite matrix also influences the growth of SiC whisker. With the nucleation points provided by graphite matrix defects increasing, the production of SiC whisker incleases and SiC whisker starts to overlap with each other. The formation process of SiC whisker includes two steps:nucleation and growth. SiC whisker nucleates at low temperature and grows at high temperature, which follows the VLS (vapor-liquid-solid growth mechanism.

Influence of aluminum nitride interlayers on crystal orientation and piezoelectric property of aluminum nitride thin films prepared on titanium electrodes

International Nuclear Information System (INIS)

Kamohara, Toshihiro; Akiyama, Morito; Ueno, Naohiro; Nonaka, Kazuhiro; Kuwano, Noriyuki

2007-01-01

Highly c-axis-oriented aluminum nitride (AlN) thin films have been prepared on titanium (Ti) bottom electrodes by using AlN interlayers. The AlN interlayers were deposited between Ti electrodes and silicon (Si) substrates, such as AlN/Ti/AlN/Si. The crystallinity and crystal orientation of the AlN films and Ti electrodes strongly depended on the thickness of the AlN interlayers. Although the sputtering conditions were the same, the X-ray diffraction intensity of AlN (0002) and Ti (0002) planes drastically increased, and the full-width at half-maximum (FWHM) of the X-ray rocking curves decreased from 5.1 o to 2.6 o and from 3.3 o to 2.0 o , respectively. Furthermore, the piezoelectric constant d 33 of the AlN films was significantly improved from - 0.2 to - 4.5 pC/N

Bio-Inspired PVDF-Based, Mouse Whisker Mimicking, Tactile Sensor

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Mohsin Islam Tiwana

2016-10-01

Full Text Available The design and fabrication of a Polyvinylidene fluoride (PVDF based, mouse (or rodent whisker mimicking, tactile sensor is presented. Unlike previous designs reported in the literature, this sensor mimics the mouse whisker not only mechanically, but it also makes macro movements just like a real mouse whisker in a natural environment. We have developed a mathematical model and performed finite element analysis using COMSOL, in order to optimise the whisker to have the same natural frequency as that of a biological whisker. Similarly, we have developed a control system that enables the whisker mimicking sensor to vibrate at variable frequencies and conducted practical experiments to validate the response of the sensor. The natural frequency of the whisker can be designed anywhere between 35 and 110 Hz, the same as a biological whisker, by choosing different materials and physical dimensions. The control system of this sensor enables the whisker to vibrate between 5 and 236 Hz.

Preparation of Titanium nitride nanomaterials for electrode and application in energy storage

Science.gov (United States)

Tang, Shun; Cheng, Qi; Zhao, Jinxing; Liang, Jiyuan; Liu, Chang; Lan, Qian; Cao, Yuan-Cheng; Liu, Jiyan

The Titanium nitride was made by the carbamide and titanic chloride precursors. XRD results indicate that the precursor ratio N:Ti 3:1 leads to higher crystallinity. SEM and EDX demonstrated that Ti and N elements were distributed uniformly with the ratio of 1:1. The TiN used as the electrode material for supercapacitor was also studied. The specific capacities were changed from 407 F.g-1 to 385 F.g-1, 364 F.g-1 and 312 F.g-1, when the current densities were changed from 1 A.g-1 to 2 A.g-1, 5 A.g-1 and 10 A.g-1, respectively. Chronopotentiometry tests showed high coulombic efficiency. Cycling performance of the TiN electrode was evaluated by CV at a scanning rate of 50 mV.s-1 for 20,000 cycles and there was about 9.8% loss. These results indicate that TiN is a promising electrode material for the supercapacitors.

On the residual stress and picostructure of titanium nitride films. Pt. 1

International Nuclear Information System (INIS)

Perry, A.J.; Valvoda, V.; Rafaja, D.; Williamson, D.L.; Sartwell, B.D.

1992-01-01

Titanium nitride films, dual energy ion implanted with argon or krypton, have been studied with a Seemann-Bohlin fine focus goniometer at grazing angles in the range 2-10. The implantation of 1% of either gas has little effect on the lattice parameters or the residual stress. It is thought that the gas atoms are on substitutional lattice sites and are associated with vacancies created during the implantation process. At 4% of implanted gas, it precipitates out in the form of bubbles; in the case of argon these are crystalline and their lattice parameter is close to that for solid argon as recorded in the literature. The lattice parameters and the residual stresses are affected slightly by the implantation: argon reduces the former and makes the latter more tensile, whereas the krypton has the opposite effects. It is thought that the difference in behavior is due to a difference in size of the bubbles or to the greater compressibility of argon

Structural characterization of thin films of titanium nitride deposited by laser ablation

International Nuclear Information System (INIS)

Castro C, M.A.; Escobar A, L.; Camps C, E.; Mejia H, J.A.

2004-01-01

Thin films of titanium nitride were deposited using the technique of laser ablation. It was studied the effect of the density of laser energy used for ablation the target as well as of the pressure of the work gas about the structure and the hardness of the deposited thin films. Depending on the pressure of the work gas films was obtained with preferential orientation in the directions (200) and (111). At a pressure of 1 x 10 -2 Torr only the direction (200) was observed. On the other hand to the pressure of 5 x 10 -3 Torr the deposited material this formed by a mixture of the orientation (200) and (111), being the direction (111) the predominant one. Thin films of Ti N were obtained with hardness of up to 24.0 GPa that makes to these attractive materials for mechanical applications. The hardness showed an approximately linear dependence with the energy density. (Author)

Simulated radiation effects in the superinsulating phase of titanium nitride films

Directory of Open Access Journals (Sweden)

Vujisić Miloš Lj.

2011-01-01

Full Text Available This paper investigates possible effects of alpha particle and ion beam irradiation on the properties of the superinsulating phase, recently observed in titanium nitride films, by using numerical simulation of particle transport. Unique physical properties of the superinsulating state are considered by relying on a two-dimensional Josephson junction array as a model of material structure. It is suggested that radiation-induced change of the Josephson junction charging energy would not affect the current-voltage characteristics of the superinsulating film significantly. However, it is theorized that a relapse to an insulating state with thermally activated resistance is possible, due to radiation-induced disruption of the fine-tuned granular structure. The breaking of Cooper pairs caused by incident and displaced ions may also destroy the conditions for a superinsulating phase to exist. Finally, even the energy loss to phonons can influence the superinsulating state, by increasing the effective temperature of the phonon thermostat, thereby reestablishing means for an energy exchange that can support Cooper pair tunneling.

Characterisation of titanium nitride films obtained by metalorganic chemical vapor deposition (MOCVD); Caracterizacao de filmes de nitreto de titanio obtidos por MOCVD

Energy Technology Data Exchange (ETDEWEB)

Pillis, M.F., E-mail: mfpillis@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (CCTM/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencia e Tecnologia de Materiais; Franco, A.C. [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica; Araujo, E.G. de [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Sacilotti, M. [Universidade Federal de Pernambuco (IF/UFPE), Recife, PE (Brazil). Inst. de Fisica; Fundacao de Amparo a Ciencia e Tecnologia de Pernambuco (FACEPE), Recife, PE (Brazil)

2009-07-01

Ceramic coatings have been widely used as protective coating to improve the life of cutting tools, for corrosion protection and in microelectronics, optical and medical areas. Transition metals nitrides are of special interest due to its high hardness and thermal stability. In this work thin films of titanium nitride were obtained by MOCVD (metalorganic chemical vapor deposition) process. The tests were carried out for 1h at 700 deg C under 80 and 100 mbar of pressure. The characterization was made by using scanning electron microscopy coupled with dispersive energy analysis, and X-ray diffraction. Preliminary results suggested that Ti{sub 2}N phase was formed and that the growth rate varied between 4 and 13 nm/min according to the process parameter considered. (author)

A novel anti-frictional multiphase layer produced by plasma nitriding of PVD titanium coated ZL205A aluminum alloy

Science.gov (United States)

Lu, C.; Yao, J. W.; Wang, Y. X.; Zhu, Y. D.; Guo, J. H.; Wang, Y.; Fu, H. Y.; Chen, Z. B.; Yan, M. F.

2018-02-01

The heat treatment (consisting of solid solution and aging), is integrated with the nitriding process of titanium coated ZL205A aluminum alloy to improve the surface and matrix mechanical properties simultaneously. Two-step duplex treatment is adopted to prepare the gradient multiphase layer on a magnesium-free ZL205A aluminum-copper based alloy. Firstly, pure titanium film is deposited on the aluminum alloy substrate using magnetron sputtering. Secondly, the Ti-coated specimen is nitrided at the solid solution temperature of the substrate alloying elements in a gas mixture of N2 and H2 and aged at 175 °C. The microstructure evolution, microhardness as well as the wear resistance of obtained multiphase layers are investigated by means of scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometer (EDS), microhardness tester and pin-on-disc tribometer. The multiphase layer, dominated by TiN0.3 or Al3Ti, is prepared with significantly increased layer depth after duplex treatment. The surface hardness of multiphase layer is remarkably improved from 23.7HV to 457HV. The core matrix hardness is also increased to 65HV after aging. The wear rate of the multiphase layer decreases about 55.22% and 49.28% in comparison with the aged and Ti coated specimens, respectively. The predominant wear mechanism for the multiphase layer is abrasive and oxidation, but severe adhesive wear for the aged and Ti coated specimens.

Single-Atom Catalyst of Platinum Supported on Titanium Nitride for Selective Electrochemical Reactions.

Science.gov (United States)

Yang, Sungeun; Kim, Jiwhan; Tak, Young Joo; Soon, Aloysius; Lee, Hyunjoo

2016-02-05

As a catalyst, single-atom platinum may provide an ideal structure for platinum minimization. Herein, a single-atom catalyst of platinum supported on titanium nitride nanoparticles were successfully prepared with the aid of chlorine ligands. Unlike platinum nanoparticles, the single-atom active sites predominantly produced hydrogen peroxide in the electrochemical oxygen reduction with the highest mass activity reported so far. The electrocatalytic oxidation of small organic molecules, such as formic acid and methanol, also exhibited unique selectivity on the single-atom platinum catalyst. A lack of platinum ensemble sites changed the reaction pathway for the oxygen-reduction reaction toward a two-electron pathway and formic acid oxidation toward direct dehydrogenation, and also induced no activity for the methanol oxidation. This work demonstrates that single-atom platinum can be an efficient electrocatalyst with high mass activity and unique selectivity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Corrosion-electrochemical characteristics of oxide-carbide and oxide-nitride coatings formed by electrolytic plasma

International Nuclear Information System (INIS)

Tomashov, N.D.; Chukalovskaya, T.V.; Medova, I.L.; Duradzhi, V.N.; Plavnik, G.M.

1990-01-01

The composition, structure, microhardness and corrosion-electrochemical properties of oxide-carbide and oxide-nitride coatings on titanium in 5n H 2 SO 4 , 50 deg, produced by the method of chemical-heat treatment in electrolytic plasma, containing saturation components of nitrogen and carbon, were investigated. It is shown that the coatings produced have increased hardness, possess high corrosion resistance in sulfuric acid solution at increased temperature, as to their electrochemcial behaviour they are similar to titanium carbide and nitride respectively. It is shown that high corrosion resistance is ensured by electrochemical mechanism of the oxide-carbide and oxide-nitride coating protection

Robust non-carbon titanium nitride nanotubes supported Pt catalyst with enhanced catalytic activity and durability for methanol oxidation reaction

International Nuclear Information System (INIS)

Xiao, Yonghao; Zhan, Guohe; Fu, Zhenggao; Pan, Zhanchang; Xiao, Chumin; Wu, Shoukun; Chen, Chun; Hu, Guanghui; Wei, Zhigang

2014-01-01

By the combination of solvothermal alcoholysis and post-nitriding method, titanium nitride nanotubes (TiN NTs), with high surface area, hollow and interior porous structure are prepared successfully and used at a support for Pt nanoparticles. The TiN NTs supported Pt (Pt/TiN NTs) catalyst displays enhanced activity and durability towards methanol oxidation reaction (MOR) compared with the commercial Pt/C (E-TEK) catalyst. X ray diffraction (XRD), nitrogen adsorption/desorption, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) measurements are performed to investigate the physicochemical properties of the synthesized catalyst. SEM and TEM images reveal that the wall of the TiN NTs is porous and Pt nanoparticles supported on the dendritic TiN nanocrystals exhibit small size and good dispersion. Effects of inherent corrosion-resistant, tubular and porous nanostructures and electron transfer due to the strong metal–support interactions of TiN NTs contribute to the enhanced catalytic activity and stability of Pt/TiN NTs towards the MOR

Composition of Whiskers Grown on Copper in Repository Environment

International Nuclear Information System (INIS)

Hermansson, Hans-Peter; Tarkpea, Peeter; Holgersson, Stellan

2001-11-01

There is a hypothesis that a special family of local attack on copper based on growth of whiskers of sulfide, oxide/hydroxide and also carbonate/malachite could appear in the repository environment. It was earlier demonstrated that such whiskers could grow in a laboratory simulated repository environment, containing sulfide. A suggested composition of whiskers has earlier been forwarded but was not demonstrated. In the present work whiskers and their substrates were grown and characterized by investigations with a combination of SEM-EDS, XRD and LRS (Laser Raman Spectroscopy) techniques. SEM-EDS was used to determine the morphology and an elemental composition and distribution of whiskers and their substrate. A special effort was made to find out if the whisker growth is of a local or global character. The phase status could be determined locally and globally by combining XRD and LRS techniques on whiskers and substrates. Ideally, LRS gives a phase resolution down to a radius of 1 μm on the sample surface. This is of great value as it is of interest to study if there are phase differences in different parts of a whisker. Such information is important to understand the whisker growth mechanism. Cylindrical samples of pure copper were prepared and exposed to the selected de-aerated model groundwater containing, among other ions, chloride and sulfide. Exposure was performed in sealed glass flasks under de-aerated conditions. After exposure the copper sample was investigated on the surface, in cross section and on whiskers using the mentioned techniques. The results show that a black, easily detached layer of corrosion products is formed on the sample surface. The corrosion layer was subdivided into at least five parallel strata (probably more) of different composition. Numerous small pits and shallow pitting attacks with a larger radius were observed in the copper metal and the metal surface was in general very rough. A multitude of very easily detached whiskers or

Bulk Thermoelectric Materials Reinforced with SiC Whiskers

Science.gov (United States)

Akao, Takahiro; Fujiwara, Yuya; Tarui, Yuki; Onda, Tetsuhiko; Chen, Zhong-Chun

2014-06-01

SiC whiskers have been incorporated into Zn4Sb3 compound as reinforcements to overcome its extremely brittle nature. The bulk samples were prepared by either hot-extrusion or hot-pressing techniques. The obtained products containing 1 vol.% to 5 vol.% SiC whiskers were confirmed to exhibit sound appearance, high density, and fine-grained microstructure. Mechanical properties such as the hardness and fracture resistance were improved by the addition of SiC whiskers, as a result of dispersion strengthening and microstructural refinement induced by a pinning effect. Furthermore, crack deflection and/or bridging/pullout mechanisms are invoked by the whiskers. Regarding the thermoelectric properties, the Seebeck coefficient and electrical resistivity values comparable to those of the pure compound are retained over the entire range of added whisker amount. However, the thermal conductivity becomes large with increasing amount of SiC whiskers because of the much higher conductivity of SiC relative to the Zn4Sb3 matrix. This results in a remarkable degradation of the dimensionless figure of merit in the samples with addition of SiC whiskers. Therefore, the optimum amount of SiC whiskers in the Zn4Sb3 matrix should be determined by balancing the mechanical properties and thermoelectric performance.

Temperature-dependent transformation from whisker- to nanoparticle-strengthened composite interface in the Al{sub 2}O{sub 3}/Ag-based alloy system and mechanical properties of the joints

Energy Technology Data Exchange (ETDEWEB)

Wang, Yifeng; Cao, Jian, E-mail: cao_jian@hit.edu.cn; Wang, Zhijie; Chen, Zhe; Song, Xiaoguo; Feng, Jicai

2015-11-15

Al{sub 4}B{sub 2}O{sub 9}-whisker-coated Al{sub 2}O{sub 3} ceramics were bonded by AgCu–4.5 wt.%Ti alloy in vacuum. The microstructure of the whisker-coated Al{sub 2}O{sub 3} joints was investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. A continuous (Cu,Al){sub 3}Ti{sub 3}O layer formed against the alloy at lower bonding temperatures, and a complex transition zone bordering the whiskers was observed, which consisted of Ag nanoparticles, titanium oxides, TiB{sub 2}, (Cu,Al){sub 3}Ti{sub 3}O nanoparticles and possible Ag{sub 3}Al. As the bonding temperature increased, the Al{sub 2}O{sub 3}/AgCuTi interface was found to transform from whisker- to nanoparticle-strengthened composite region. Bend test results revealed that both the whiskers grown on Al{sub 2}O{sub 3} and the dispersive nanoscale products in the alloy played positive roles in improving the joint properties. The maximum bend strength of the whisker-coated Al{sub 2}O{sub 3} joints was 313 MPa at the bonding temperature of 820 °C. - Highlights: • Al{sub 4}B{sub 2}O{sub 9}-whisker-coated Al{sub 2}O{sub 3} ceramics were bonded by AgCu–4.5 wt.%Ti alloy in vacuum. • Microstructures of whisker-coated Al{sub 2}O{sub 3} joints were investigated in detail. • Both whiskers and the dispersive nanoscale products can improve the joint properties. • The maximum bend strength of the whisker-coated Al{sub 2}O{sub 3} joints was 313 MPa.

Whiskers and Localized Corrosion on Copper in Repository Environment

International Nuclear Information System (INIS)

Hermansson, Hans-Peter; Gillen, Peter

2004-03-01

Previous studies have demonstrated that whiskers (thread/hair shaped structures) can form on copper in a sulphide containing environment. A remaining important question is whether the attack on the copper metal surface beneath a whisker is of a localized or of a general nature. This issue has not been clarified as whiskers are very fragile and have always detached and fallen off from the surface at some stage of handling. It has therefore been very difficult to link the growth root of the whisker to underlying structures in the metal surface. A study was therefore initiated to settle the important issue of the relation between whisker position and the type of underlying metal attack. The usage of a porous medium was originally planned to support the whiskers in order to keep them in place and by post examinations characterize the nature of the whisker roots and thus the type of attack on the metal. However, the early stages of the present experimental work clearly indicated that other ways of study were necessary. A photographic method for the registration and positioning of whisker growth was therefore developed. It proved to be a successful means to coordinate whisker position and to link it with the attack on the underlying metal. Shortage of sulphide in previous experiments caused a retarded growth rate of whiskers. Therefore, in present experiments the sulphide concentration was kept at a more constant level throughout an experiment and a hindered whisker growth did not limit the attack on underlying metal. Whiskers and substrates were observed with a video camera throughout an experiment and the phase composition was examined with Laser Raman Spectroscopy, LRS and the Raman video microscope. Post examinations were also performed using light optical microscopy. By combining the results from the optical methods it has been possible to distinguish two kinds of whisker roots (small/large diameter) with the underlying metal surface. It has also been demonstrated

Microencapsulation of silicon nitride particles with yttria and yttria-alumina precursors

International Nuclear Information System (INIS)

Garg, A.K.; De Jonghe, L.C.

1990-01-01

Procedures are described to deposit uniform layers of yttria and yttria-alumina precursors on fine powders and whiskers of silicon nitride. The coatings were produced by aging at elevated temperatures aqueous systems containing the silicon nitride core particles, yttrium and aluminum nitrates, and urea. Optimum concentrations of the core particles, in relation to the reactants, were established to promote surface deposition of the oxide precursors. Polymeric dispersants were used effectively to prevent agglomeration of the solids during the microencapsulation process. The morphology of the powders was characterized using scanning and transmission electron microscopy. The mechanisms for the formation of the coated layers are discussed. A description is provided that allows qualitative assessment of the experimental factors that determine microencapsulation by a slurry method

Degradation of nitride coatings in low-pressure gas discharge plasma

Science.gov (United States)

Ivanov, Yurii; Shugurov, Vladimir; Krysina, Olga; Petrikova, Elizaveta; Tolkachev, Oleg

2017-12-01

The paper provides research data on the defect structure, mechanical characteristics, and tribological properties of commercially pure VT1-0 titanium exposed to surface modification on a COMPLEX laboratory electron-ion plasma setup which allows nitriding, coating deposition, and etching in low-pressure gas discharge plasma in a single vacuum cycle. It is shown that preliminary plasma nitriding forms a columnar Ti2N phase in VT1-0 titanium and that subsequent TiN deposition results in a thin nanocrystalline TiN layer. When the coating-substrate system is etched, the coating fails and the tribological properties of the material degrade greatly.

Synthesis and characterization of titanium-vanadium ternary nitride (Ti{sub x}V{sub 1}-xN).; Sintesis y caracterizacion del nitruro ternario de titanio y vanadio (Ti{sub x}V{sub 1}-xN)

Energy Technology Data Exchange (ETDEWEB)

Roldan, M. A.; Alcala, M. D.; Ortega, A.; Real, C.

2011-07-01

Titanium-Vanadium nitride (TiVN) has been prepared from carbothermal reduction of corresponding oxides and also by direct nitridation of a mix of two metals employing the ATVC method. The characterization of the final product by X-ray diffraction, scanning electron microscopy, electron energy loss (EELS), and X-ray absorption spectroscopy (XAS) is presented. The synthesis of the ternary nitride has been possible in all range of composition and the final product is obtained with nano metric particle size and a high microhardness after sintering. (Author) 58 refs.

Visible-light photocatalytic activity of nitrided TiO2 thin films

International Nuclear Information System (INIS)

Camps, Enrique; Escobar-Alarcon, L.; Camacho-Lopez, Marco Antonio; Casados, Dora A. Solis

2010-01-01

TiO 2 thin films have been applied in UV-light photocatalysis. Nevertheless visible-light photocatalytic activity would make this material more attractive for applications. In this work we present results on the modification of titanium oxide (anatase) sol-gel thin films, via a nitriding process using a microwave plasma source. After the treatment in the nitrogen plasma, the nitrogen content in the TiO 2 films varied in the range from 14 up to 28 at%. The titanium oxide films and the nitrided ones were characterized by XPS, micro-Raman spectroscopy and UV-vis spectroscopy. Photocatalytic activity tests were done using a Methylene Blue dye solution, and as catalyst TiO 2 and nitrided TiO 2 films. The irradiation of films was carried out with a lamp with emission in the visible (without UV). The results showed that the nitrided TiO 2 films had photocatalytic activity, while the unnitrided films did not.

Chemical vapor deposition of tetraboron silicide whiskers

International Nuclear Information System (INIS)

Motozima, Seizi; Sugiyama, Kozoh; Takahashi, Yasutaka

1975-01-01

Growth conditions of B 4 Si whiskers were investigated at the temperature range of 1000 - 1100 0 C. Optimum composition of halides was determined as BCl 3 /SiCl 4 =2 - 0.5, and BCl 3 =1 - 6 vol%, SiCl 4 =1 - 7 vol%. Gold had an excellent impurity effect with optimum concentration of 20 - 50 μg/cm 2 on whisker growth, and gave wool like whiskers of 0.1 - 1 μ in thickness and 0.5 - 2 mm in length. B 4 Si whisker growth was explained in terms of a tip VLS mechanism, for a drop-like deposit of impurity was observed on each tip. (auth.)

Modification of the surfaces of stainless steel during titanium nitride deposition by a dynamic mixing method

Science.gov (United States)

Yokota, Katsuhiro; Tamura, Susumu; Nakamura, Kazuhiro; Horiguchi, Motohiro; Nakaiwa, Hiroki; Sugimoto, Takashi; Akamatsu, Katsuya; Nakao, Kazuyoshi

2000-05-01

Surfaces of stainless steel SUS304 were coated with titanium nitride (TiN) at temperatures ranging from 400°C to 770°C using a dynamic mixing technique. The N+ ions were accelerated at energies of 0.5-2.0 keV, and were implanted into the stainless steel. The composition of the prepared TiN films was measured using Rutherford backscattering spectrometry with He ions at an energy of 2.0 MeV. Intermediate layers containing compounds such as FesNq, Cr2N, and CrFe were formed between the TiN films and substrates at substrate temperatures higher than 700°C. The thickness of the TiN films decreased significantly when the intermediate layers were formed.

Metal surface nitriding by laser induced plasma

Science.gov (United States)

Thomann, A. L.; Boulmer-Leborgne, C.; Andreazza-Vignolle, C.; Andreazza, P.; Hermann, J.; Blondiaux, G.

1996-10-01

We study a nitriding technique of metals by means of laser induced plasma. The synthesized layers are composed of a nitrogen concentration gradient over several μm depth, and are expected to be useful for tribological applications with no adhesion problem. The nitriding method is tested on the synthesis of titanium nitride which is a well-known compound, obtained at present by many deposition and diffusion techniques. In the method of interest, a laser beam is focused on a titanium target in a nitrogen atmosphere, leading to the creation of a plasma over the metal surface. In order to understand the layer formation, it is necessary to characterize the plasma as well as the surface that it has been in contact with. Progressive nitrogen incorporation in the titanium lattice and TiN synthesis are studied by characterizing samples prepared with increasing laser shot number (100-4000). The role of the laser wavelength is also inspected by comparing layers obtained with two kinds of pulsed lasers: a transversal-excited-atmospheric-pressure-CO2 laser (λ=10.6 μm) and a XeCl excimer laser (λ=308 nm). Simulations of the target temperature rise under laser irradiation are performed, which evidence differences in the initial laser/material interaction (material heated thickness, heating time duration, etc.) depending on the laser features (wavelength and pulse time duration). Results from plasma characterization also point out that the plasma composition and propagation mode depend on the laser wavelength. Correlation of these results with those obtained from layer analyses shows at first the important role played by the plasma in the nitrogen incorporation. Its presence is necessary and allows N2 dissociation and a better energy coupling with the target. Second, it appears that the nitrogen diffusion governs the nitriding process. The study of the metal nitriding efficiency, depending on the laser used, allows us to explain the differences observed in the layer features

Synthesis of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} whiskers and cross-whisker intrinsic Josephson junction

Energy Technology Data Exchange (ETDEWEB)

Hatano, T.; Takano, Y.; Arisawa, S.; Ishii, A.; Togano, K. [National Research Inst. for Metals, Tsukuba, Ibaraki (Japan); Fukuyo, A. [Science Univ. of Tokyo (Japan)

2001-03-01

A synthesis technique of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} single-crystal whiskers was studied. The whiskers were synthesized by heating glassy melt-quenched Bi-Sr-Ca-Cu-O (3:2:2:4 in cationic ratio) plates. The atmospheric condition of the whisker growth, especially oxygen partial pressure and gas flow, was investigated. It was found out that the whisker growth rate shows a maximum at P{sub O2}=2/3 bar. For the crystalline quality of the whiskers, the airtight condition was found to be useful as compared to the conventional oxygen stream condition. The crystalline quality, especially the straightness and morphology of the surface, could be improved by keeping the growing whiskers under the equilibrium P{sub Bi} condition. Over 20-mm-long whisker crystals have been successfully synthesized by choosing optimum oxygen partial pressure around the P{sub O2}=2/3 bar in the airtight condition. The growth condition and mechanism of the Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} whiskers were investigated by an in-situ high-temperature x-ray diffraction analysis and an in-situ high-temperature microscope observation. It was found that the whiskers grow in a partially melted state at a temperature of 10-40 degrees below the melting point. The result obtained demonstrates that Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} whiskers grow at their bottom by the conventional liquid-phase growth mechanism, as was proposed by Matsubara et al. (author)

Tin Whisker Testing and Modeling

Science.gov (United States)

2015-11-01

to 25°C/85%RH. The greatest whisker nucleation and growth occurred on the Cu alloy lead terminations. During high humidity isothermal exposure...Circuits, Lead-Free Solder, Electronic Assembly, Humidity Exposure, Thermal Cycling, Corrosion, Contamination, Whisker Length Statistics 16. SECURITY...rework fluxes, and immersion Sn finished Cu circuit board pads. The assemblies were exposed to various thermal cycling and isothermal high humidity and

Pressureless sintering of whisker-toughened ceramic composites

Science.gov (United States)

Tiegs, T.N.

1993-05-04

A pressureless sintering method is disclosed for use in the production of whisker-toughened ceramic composites wherein the sintered density of composites containing up to about 20 vol. % SiC whiskers is improved by reducing the average aspect ratio of the whiskers to from about 10 to about 20. Sintering aids further improve the density, permitting the production of composites containing 20 vol. % SiC with sintered densities of 94% or better of theoretical density by a pressureless sintering method.

Corrosion Behavior of Titanium Based Ceramic Coatings Deposited on Steels

OpenAIRE

Ali, Rania

2016-01-01

Titanium based ceramic films are increasingly used as coating materials because of their high hardness, excellent wear resistance and superior corrosion resistance. Using electrochemical and spectroscopic techniques, the electrochemical properties of different coatings deposited on different steels under different conditions were examined in this study. Thin films of titanium nitride (TiN), titanium diboride (TiB2), and titanium boronitride with different boron concentrations (TiBN-1&2) w...

[Biomimetic mineralization of rod-like cellulose nano-whiskers and spectrum analysis].

Science.gov (United States)

Qu, Ping; Wang, Xuan; Cui, Xiao-xia; Zhang, Li-ping

2012-05-01

Cellulose nano-whiskers/nano-hydroxyapatite composite was prepared with biomimetic mineralization using rod-like cellulose nano-whiskers as template. The cellulose nano-whiskers and cellulose nano-whiskers/nano-hydroxyapatite composite were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope-energy dispersive analysis of X-rays (SEM-EDXA). Variation and distribution of carbon, oxygen, calcium, and phosphorus in the composites were studied. The morphologies and growth mechanism of nano-hydroxyapatite were analyzed. The results showed that nano-hydroxyapatite was formed on the surface of cellulose nano-whiskers; the carbon-oxygen ratio of cellulose nano-whiskers and cellulose nano-whiskers/nano-hydroxyapatite composite was 1.81 and 1.54, respectively; the calcium-phosphorus ratio of the composite was 1.70. The nucleation of nano-hydroxyapatite was around the hydroxyl groups of cellulose nano-whiskers. It is suggested that there is coordination between the hydroxyl groups of cellulose nano-whiskers and calcium ions of nano-hydroxyapatite. The nano-hydroxyapatite can distribute in the matrix of cellulose nano-whiskers. From the atomic force microscope (AFM) images, we can see that the diameter of the spherical nano-hydroxyapatite particles was about 20 nm.

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.

Deposition of titanium nitride on Si(1 0 0) wafers using plasma focus

International Nuclear Information System (INIS)

Hussain, Tousif; Ahmad, R.; Khan, I.A.; Siddiqui, Jamil; Khalid, Nida; Bhatti, Arshad Saleem; Naseem, Shahzad

2009-01-01

Titanium nitride thin films were deposited on Si(1 0 0) substrates by using a low energy (2.3 KJ) Mather-type plasma focus device. The composition of the deposited films was characterized by X-ray diffraction (XRD). The crystallite size has strong dependence on the numbers of focus shots. The crystallinity of TiN thin films is found to increase with increasing the number of focus shots. The effect of different number of focus shots on micro structural changes of thin films was characterized by Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM). SEM results showed net-like structure for film deposited for 15 numbers of shots, which are elongated grains of Si 3 N 4 in amorphous form embedded into TiN crystals. The average surface roughness was calculated from AFM images of the thin films. These results indicated that the average surface roughness increased for films deposited with increased number of focus shots. The least crystallite size and roughness are observed for film deposited with 25 focus shots.

Chiro-plasmonic refractory metamaterial with titanium nitride (TiN) core–shell nanohelices

Science.gov (United States)

Venkataramanababu, Sruthi; Nair, Greshma; Deshpande, Preeti; A, Jithin M.; Mohan, Sangeneni; Ghosh, Ambarish

2018-06-01

Chiral metamaterials are obtained by assembling plasmonic elements in geometries with broken mirror symmetry, which can have promising applications pertaining to generation, manipulation and detection of optical polarisation. The materials used to fabricate this promising nanosystem, especially in the visible–NIR regime, are limited to noble metals such as Au and Ag. However, they are not stable at elevated temperatures and in addition, incompatible with CMOS technologies. We demonstrate that it is possible to develop a chiro-plasmonic system based on a refractory material such as titanium nitride (TiN) which does not have these disadvantages. The building block of our metamaterial is a novel core–shell helix, obtained by coating TiN over silica nanohelices. These were arranged in a regular two-dimensional array over cm-scale areas, made possible by the use of scalable fabrication techniques such as laser interference lithography, glancing angle deposition and DC magnetron sputtering. The measured chiro-optical response was extremely broadband (1400 nm), and had contributions from individual, as well as collective plasmon modes of the interacting nanohelices, whose spectral characteristics could be easily controlled by varying the direction of the incident radiation.

Effect of titanium nitride coating on physical properties of three-dimensional graphene

Energy Technology Data Exchange (ETDEWEB)

Dabir, Fatemeh, E-mail: f.dabir@modares.ac.ir [Materials Eng. Department, Tarbiat Modares University, 1411713116, Tehran (Iran, Islamic Republic of); Sarraf-Mamoory, Rasoul, E-mail: rsarrafm@modares.ac.ir [Materials Eng. Department, Tarbiat Modares University, 1411713116, Tehran (Iran, Islamic Republic of); Loeblein, Manuela, E-mail: manuela001@e.ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, 639798 (Singapore); CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, 637553 (Singapore); Tsang, Siu Hon, E-mail: shtsang@ntu.edu.sg [CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, 637553 (Singapore); Teo, Edwin Hang Tong, E-mail: htteo@ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, 639798 (Singapore)

2015-11-30

Graphical abstract: - Highlights: • TiN was coated on 3D graphene by chemical method, followed by annealing at NH{sub 3}. • Effect of TiN coating on physical properties of 3DG was investigated. • TiN coating modified surface properties of 3DG, while retaining its skeleton. • Average number of graphene layers increased after annealing of 3DG at NH{sub 3}. • Annealing of 3DG at NH{sub 3} resulted in locally nitrogen doping. - Abstract: In this paper, titanium nitride (TiN) was applied on the surface and into the porous structure of three-dimensional graphene (3DG) by chemical method. This method consists of immersing 3DG into a solution containing Ti ions and annealing under ammonia atmosphere at 850 °C. The effects of TiN coating and high temperature annealing under NH{sub 3} on the physical properties of 3DG were investigated. For this purpose, the 3DG samples, with and without TiN coating, were characterized via XRD, SEM, XPS, and Raman spectroscopy. Then, the electrical resistivity, work function, and wettability of samples were determined by Van der Pauw method, contact angle meter, and UV photoelectron spectroscopy (UPS), respectively. The results showed that an almost pure and very crystalline TiN phase with titanium/nitrogen atomic ratio of 1.09 was formed on the 3DG network. Annealing of 3DG under NH{sub 3} resulted in locally doping of graphene with nitrogen and generation of defects in its structure. After TiN coating, the work function value of 3DG (5 eV) was reduced to 4.68 eV, while its initial water contact angle decreased from 127° to 83°.

Anatomical pathways involved in generating and sensing rhythmic whisker movements

Directory of Open Access Journals (Sweden)

Laurens W.J. Bosman

2011-10-01

Full Text Available The rodent whisker system is widely used as a model system for investigating sensorimotor integration, neural mechanisms of complex cognitive tasks, neural development, and robotics. The whisker pathways to the barrel cortex have received considerable attention. However, many subcortical structures are paramount to the whisker system. They contribute to important processes, like filtering out salient features, integration with other senses and adaptation of the whisker system to the general behavioral state of the animal. We present here an overview of the brain regions and their connections involved in the whisker system. We do not only describe the anatomy and functional roles of the cerebral cortex, but also those of subcortical structures like the striatum, superior colliculus, cerebellum, pontomedullary reticular formation, zona incerta and anterior pretectal nucleus as well as those of level setting systems like the cholinergic, histaminergic, serotonergic and noradrenergic pathways. We conclude by discussing how these brain regions may affect each other and how they together may control the precise timing of whisker movements and coordinate whisker perception.

Core-shell titanium dioxide-titanium nitride nanotube arrays with near-infrared plasmon resonances

Science.gov (United States)

Farsinezhad, Samira; Shanavas, Thariq; Mahdi, Najia; Askar, Abdelrahman M.; Kar, Piyush; Sharma, Himani; Shankar, Karthik

2018-04-01

Titanium nitride (TiN) is a ceramic with high electrical conductivity which in nanoparticle form, exhibits localized surface plasmon resonances (LSPRs) in the visible region of the solar spectrum. The ceramic nature of TiN coupled with its dielectric loss factor being comparable to that of gold, render it attractive for CMOS polarizers, refractory plasmonics, surface-enhanced Raman scattering and a whole host of sensing applications. We report core-shell TiO2-TiN nanotube arrays exhibiting LSPR peaks in the range 775-830 nm achieved by a simple, solution-based, low cost, large area-compatible fabrication route that does not involve laser-writing or lithography. Self-organized, highly ordered TiO2 nanotube arrays were grown by electrochemical anodization of Ti thin films on fluorine-doped tin oxide-coated glass substrates and then conformally coated with a thin layer of TiN using atomic layer deposition. The effects of varying the TiN layer thickness and thermal annealing on the LSPR profiles were also investigated. Modeling the TiO2-TiN core-shell nanotube structure using two different approaches, one employing effective medium approximations coupled with Fresnel coefficients, resulted in calculated optical spectra that closely matched the experimentally measured spectra. Modeling provided the insight that the observed near-infrared resonance was not collective in nature, and was mainly attributable to the longitudinal resonance of annular nanotube-like TiN particles redshifted due to the presence of the higher permittivity TiO2 matrix. The resulting TiO2-TiN core-shell nanotube structures also function as visible light responsive photocatalysts, as evidenced by their photoelectrochemical water-splitting performance under light emitting diode illumination using 400, 430 and 500 nm photons.

The development of SiC whisker fabrication technology for nuclear applications

International Nuclear Information System (INIS)

Kang, Thae Khapp; Kuk, Il Hiun; Kim, Chang Kyu; Lee, Jae Chun; Lee, Ho Jin; Park, Soon Dong; Im, Gyeong Soo

1991-02-01

Some important experiments for whisker growth reactions, fabrication processes, and experiments for fabricarion of whisker reinforced composites have been performed. In order to investigate growth reaction of SiC whiskers, a conventional carbothermic reaction was tested. Based on the results of carbothermic process, a new process called silicothermic reaction was planned and some basic experiments were performed. Reaction characteristics of silicon monoxide, core material for SiC whisker growth in both of the reactions were investigated for basic data. Additionally, a hydrofluoric acid leaching process was tested for developing SiC whisker recovery process, and powder metallurgy process and melt sqeeze process were tried to develop aluminum-SiC whisker composites. (Author)

Microstructure and growth mechanism of tin whiskers on RESn3 compounds

International Nuclear Information System (INIS)

Li Caifu; Liu Zhiquan

2013-01-01

Graphical abstract: Large amount of intact tin whiskers were firstly prepared without post handling, and their microstructures were investigated systematically with TEM. A growth model was proposed to explain the observed growth characteristics from Sn–RE alloys. - Abstract: An exclusive method was developed to prepare intact tin whiskers as transmission electron microscope specimens, and with this technique in situ observation of tin whisker growth from RESn 3 (RE = Nd, La, Ce) film specimen was first achieved. Electron irradiation was discovered to have an effect on the growth of a tin whisker through its root. Large quantities of tin whiskers with diameters from 20 nm to 10 μm and lengths ranging from 50 nm to 500 μm were formed at a growth rate of 0.1–1.8 nm s −1 on the surface of RESn 3 compounds. Most (>85%) of these tin whiskers have preferred growth directions of 〈1 0 0〉, 〈0 0 1〉, 〈1 0 1〉 and 〈1 0 3〉, as determined by statistics. This kind of tin whisker is single-crystal β-Sn even if it has growth striations, steps and kinks, and no dislocations or twin or grain boundaries were observed within the whisker body. RESn 3 compounds undergo selective oxidation during whisker growth, and the oxidation provides continuous tin atoms for tin whisker growth until they are exhausted. The driving force for whisker growth is the compressive stress resulting from the restriction of the massive volume expansion (38–43%) during the oxidation by the surface RE(OH) 3 layer. Tin atoms diffuse and flow to feed the continuous growth of tin whiskers under a compressive stress gradient formed from the extrusion of tin atoms/clusters at weak points on the surface RE(OH) 3 layers. A growth model was proposed to discuss the characteristics and growth mechanism of tin whiskers from RESn 3 compounds.

Whisker-Like Formations in Sn-3.0Ag-Pb Alloys

Directory of Open Access Journals (Sweden)

Koncz-Horváth D.

2017-06-01

Full Text Available In this study, different types of whisker-like formations of Sn-3.0Ag based alloy were presented. In the experimental process the amount of Pb element was changed between 1000 and 2000 ppm, and the furnace atmosphere and cooling rate were also modified. The novelty of this work was that whisker-like formations in macro scale size were experienced after an exothermic reaction. The whiskers of larger sizes than general provided opportunities to investigate the microstructure and the concentration nearby the whiskers. In addition, the whisker-like formations from Sn-Ag based bulk material did not only consist of pure tin but tin and silver phases. The whisker-like growth appeared in several forms including hillock, spire and nodule shaped formations in accordance with parameters. It was observed that the compound phases were clustered in many cases mainly at hillocks.

Vortex Shedding in the Wake Induced by a Real Elephant Seal Whisker

Science.gov (United States)

Turk, Jodi; Omilion, Alexis; Zhang, Wei; Kim, Jeong-Jae; Kim, Jeong-Ju; Choi, Woo-Rak; Lee, Sang-Joon

2017-11-01

Biomimicry has been adopted to create innovative solutions in a vast range of applications. One such application is the design of seal-whisker-inspired flow sensors for autonomous underwater vehicles (AUVs). In dark, cramped, and unstable terrain AUVs are not able to maneuver using visual and sonar-based navigation. Hence, it is critical to use underwater flow sensors to accurately detect minute disturbances in the surroundings. Certain seal whiskers exhibit a unique undulating three-dimensional morphology that can reduce vortex induced vibrations (VIVs) if the major axis of the whisker cross-section is aligned to the inflow. This allows the seal to precisely track prey fish upstream using solely their whiskers. The current study aims to understand the effect of a real seal whisker's morphology on the vortex shedding behavior. Despite extensive studies of wake induced by scaled whisker-like models, the vortex shedding in the wake of a real seal whisker is not well understood. A series of experiments are conducted with a high-speed Particle Imaging Velocimetry (PIV) system in a water channel to examine the vortex shedding downstream from a smooth whisker and an undulating whisker at a Reynolds number of a few hundred. Results of the vortex shedding induced by real seal whiskers can provide insights on developing high-sensitivity underwater flow sensors for AUVs and other whisker-inspired structures.

Oxidation of nitride films in aqueous solution: Correlation between surface analysis and electrochemical studies

International Nuclear Information System (INIS)

Brown, R.; Alias, M.N.

1994-01-01

Ac impedance and dc polarization tests of 304 stainless steels coated by cathodic arc plasma deposition (CAPD) titanium nitride and zirconium nitride were conducted in aqueous chloride solution. Cyclic polarization data suggested passive films were formed over the nitride coatings which are most likely hydrated titanium oxide and zirconium oxides. ESCA analysis of fresh samples and samples exposed during impedance tests indicated a layer rich in oxygen over the ZrN coating after exposure but not over TiN coating. Chemical shifts in the Zr 3d 5/2 core electrons indicate transformation from ZrN to its oxide; the shifts in Ti 2P 3/2 did not support the change from TiN to its oxide. The influence of these shifts on corrosion protection is documented

Characterization of hard nitride and carbide titanium and zirconium coatings on high-speed steel cutting tool inserts

International Nuclear Information System (INIS)

Fenske, G.; Kaufherr, N.; Albertson, C.; Mapalo, G.; Nielsen, R.; Kaminsky, M.

1986-01-01

Hard nitride and carbide coatings of titanium and zirconium deposited by reactive evaporation and reactive sputtering techniques were characterized by electron microscopy and Auger spectroscopy to determine the effect of coating process on coating composition and microstructure. Analysis of the chemical composition by Auger spectroscopy revealed the coatings were of high purity with slight differences in stoichiometry depending on the coating technique. Both techniques produced coatings with a columnar microstructure. However, the reactive sputtering technique produced coarser (shorter and wider) columnar grains than the reactive evaporation technique. Furthermore, selected area diffraction analysis of reactively sputtered ZrN coatings showed a two-phased zone (hcp Zr and fcc ZrN) near the substrate/coating interface, while TiC coatings deposited by reactive sputtering and evaporation only showed a single-phase region of fcc TiC

Strengthening and toughening of poly(L-lactide) composites by surface modified MgO whiskers

Energy Technology Data Exchange (ETDEWEB)

Wen, Wei [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Luo, Binghong, E-mail: tluobh@jnu.edu.cn [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Qin, Xiaopeng; Li, Cairong [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Liu, Mingxian; Ding, Shan [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Zhou, Changren, E-mail: tcrz9@jnu.edu.cn [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China)

2015-03-30

Highlights: • The grafted PLLA chain on the surface of g-MgO whisker was ruled out by FTIR spectroscopy and TG/DTG analyses. • The excellent dispersion of g-MgO whiskers and the strong interfacial adhesion of g-MgO whiskers/PLLA composite were proved by FSEM. • Comparing to MgO particles and MgO whiskers, fibrous-like g-MgO whiskers are the most effective reinforcing and toughening fillers for PLLA. - Abstract: To improve both the strength and toughness of poly(L-lactide) (PLLA), fibrous-like MgO whiskers with diameters of 0.15–1 μm and lengths of 15–110 μm were prepared, and subsequently surface modified with L-lactide to obtain grafted MgO whiskers (g-MgO whiskers). The structures and properties of MgO whiskers and g-MgO whiskers were studied. Then, a series of MgO whiskers/PLLA and g-MgO whiskers/PLLA composites were prepared by solution casting method, for comparison, MgO particles/PLLA composite was prepared too. The resulting composites were evaluated in terms of hydrophilicity, crystallinity, dispersion of whiskers, interfacial adhesion and mechanical performance by means of polarized optical microscopy (POM), contact angle measurement, field emission scanning electron microscope (FSEM), transmission electron microscopy (TEM) and tensile testing. The results revealed that the crystallization rate and hydrophilicity of PLLA were improved by the introduction of MgO whiskers and g-MgO whiskers. The g-MgO whiskers can disperse more uniformly in and show stronger interfacial adhesion with the matrix than MgO whiskers as a result of the surface modification. Due to the bridge effect of the whiskers and the excellent interfacial adhesion between g-MgO whiskers and PLLA, g-MgO whiskers/PLLA composites exhibited remarkably higher strength, modulus and toughness compared to the pristine PLLA, MgO particles/PLLA and MgO whiskers/PLLA composites.

A novel biomimetic whisker technology based on fiber Bragg grating and its application

Science.gov (United States)

Zhao, Chenlu; Jiang, Qi; Li, Yibin

2017-09-01

The paper describes a novel, biomimetic whisker-based sensing technology following the basic design of the facial whiskers of animals such as rats and mice. The sensor consists of a 3× 2 whisker array on each side of a robot. In experiments with the artificial whiskers, the motor drives rotating whiskers, and the center wavelength of a fiber Bragg grating pasted on the whisker will shift when the whisker touches an obstacle. The distance will be obtained by processing the wavelength shift data with algorithms. Then the shape recognition can be realized by postprocessing the distance data. The experimental results prove that the whisker array is capable of accurately gathering the distance and shape information of an object.

Tin Whisker Growth and Mitigation with a Nanocrysytalline Nickel Coating

Science.gov (United States)

Janiuk, Szymon

Tin whiskers are a problem in the electronics industry since the EU banned the use of lead in Pb-Sn solders as part of the Restriction of Hazardous Substances (RoHS). The biggest concern with Sn whiskers is their ability to short-circuit electronics. High reliability applications such as the aerospace, defense, healthcare, and automotive industries are at most risk. This project explores Sn whisker mitigation and prevention with the use of nanocrystalline nickel coating over Sn surfaces. Sn was plated onto a pure Cu substrate using electroplating. A high temperature and high humidity condition, at 85°C and 85% RH, was effective at growing whiskers. A nNi coating was plated over Sn/Cu coupons. After subjecting the nNi/ Sn/Cu samples through 85°C/85% RH testing conditions, no whiskers were observed penetrating the surface. These results make nNi a viable material to use as a coating to prevent the growth of Sn whiskers in electronic assemblies.

Titanium nitride (TiN) precipitation in a maraging steel during the vacuum arc remelting (VAR) process - Inclusions characterization and modeling

Science.gov (United States)

Descotes, V.; Bellot, J.-P.; Perrin-Guérin, V.; Witzke, S.; Jardy, A.

2016-07-01

Titanium Nitride (TiN) inclusions are commonly observed in a Maraging steel containing Nitrogen and Titanium and remelted in a VAR furnace. They can be easily detected by optical microscopy. A nucleus is observed next to a large number of TiN inclusions. A TEM analysis was carried out on a biphasic nucleus composed of a calcium sulfide (CaS) and a spinel (MgAl2O4), surrounded by a TiN particle. An orientation relationship between these three phases was revealed, which suggests a heterogeneous germination of the TiN particle on the nucleus by epitaxial growth. Based on this observation, on thermodynamic considerations and on previous work, a model has been developed and coupled to a numerical simulation of the VAR process to study the formation and evolution of a TiN distribution in the VAR ingot. Microsegregation is modeled using the lever rule, while the kinetics of precipitation is mainly driven by the supersaturation of the liquid bath. This model highlights the influence of the melt rate on the final size of TiN particles.

Characterisation of nano-structured titanium and aluminium nitride coatings by indentation, transmission electron microscopy and electron energy loss spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Girleanu, M., E-mail: maria.girleanu@uha.fr [Mecanique, Materiaux et Procedes de Fabrication, LPMT (EA CNRS 4365), Universite de Haute Alsace, 61 rue Albert Camus, F-68093 Mulhouse (France); Pac, M.-J.; Louis, P. [Mecanique, Materiaux et Procedes de Fabrication, LPMT (EA CNRS 4365), Universite de Haute Alsace, 61 rue Albert Camus, F-68093 Mulhouse (France); Ersen, O.; Werckmann, J. [Departement Structures et Interfaces, IPCMS (UMR CNRS 7504), Universite de Strasbourg, 23 rue du Loess, F-67087 Strasbourg (France); Rousselot, C. [Departement Micro Nano Sciences et Systemes, FEMTO-ST (UMR CNRS 6174), Universite de Franche-Comte, BP 71427, F-25211 Montbeliard (France); Tuilier, M.-H. [Mecanique, Materiaux et Procedes de Fabrication, LPMT (EA CNRS 4365), Universite de Haute Alsace, 61 rue Albert Camus, F-68093 Mulhouse (France)

2011-07-01

Titanium and aluminium nitride Ti{sub 1-x}Al{sub x}N films deposited by radiofrequency magnetron reactive sputtering onto steel substrate are examined by transmission electron microscopy over all the range of composition (x = 0, 0.5, 0.68, 0.86, 1). The deposition parameters are optimised in order to grow nitride films with low stress over all the composition range. Transmission electron microscopy cross-section images of Vickers indentation prints performed on that set of coatings show the evolution of their damage behaviour as increasing x Al content. Cubic Ti-rich nitrides consist of small grains clustered in rather large columns sliding along each other during indentation. Hexagonal Al-rich films grow in thinner columns which can be bent under the Vickers tip. Indentation tests carried out on TiN and AlN films are simulated using finite element modelling. Particular aspects of shear stresses and displacements in the coating/substrate are investigated. The growth mode and the nanostructure of two typical films, TiN and Ti{sub 0.14}Al{sub 0.86}N, are studied in detail by combining transmission electron microscopy cross-sections and plan views. Electron energy loss spectrum taken across Ti{sub 0.14}Al{sub 0.86}N film suggests that a part of nitrogen atoms is in cubic-like local environment though the lattice symmetry of Al-rich coatings is hexagonal. The poorly crystallised domains containing Ti and N atoms in cubic-like environment are obviously located in grain boundaries and afford protection of the coating against cracking.

Characterisation of nano-structured titanium and aluminium nitride coatings by indentation, transmission electron microscopy and electron energy loss spectroscopy

International Nuclear Information System (INIS)

Girleanu, M.; Pac, M.-J.; Louis, P.; Ersen, O.; Werckmann, J.; Rousselot, C.; Tuilier, M.-H.

2011-01-01

Titanium and aluminium nitride Ti 1-x Al x N films deposited by radiofrequency magnetron reactive sputtering onto steel substrate are examined by transmission electron microscopy over all the range of composition (x = 0, 0.5, 0.68, 0.86, 1). The deposition parameters are optimised in order to grow nitride films with low stress over all the composition range. Transmission electron microscopy cross-section images of Vickers indentation prints performed on that set of coatings show the evolution of their damage behaviour as increasing x Al content. Cubic Ti-rich nitrides consist of small grains clustered in rather large columns sliding along each other during indentation. Hexagonal Al-rich films grow in thinner columns which can be bent under the Vickers tip. Indentation tests carried out on TiN and AlN films are simulated using finite element modelling. Particular aspects of shear stresses and displacements in the coating/substrate are investigated. The growth mode and the nanostructure of two typical films, TiN and Ti 0.14 Al 0.86 N, are studied in detail by combining transmission electron microscopy cross-sections and plan views. Electron energy loss spectrum taken across Ti 0.14 Al 0.86 N film suggests that a part of nitrogen atoms is in cubic-like local environment though the lattice symmetry of Al-rich coatings is hexagonal. The poorly crystallised domains containing Ti and N atoms in cubic-like environment are obviously located in grain boundaries and afford protection of the coating against cracking.

Peripheral optogenetic stimulation induces whisker movement and sensory perception in head-fixed mice.

Science.gov (United States)

Park, Sunmee; Bandi, Akhil; Lee, Christian R; Margolis, David J

2016-06-08

We discovered that optical stimulation of the mystacial pad in Emx1-Cre;Ai27D transgenic mice induces whisker movements due to activation of ChR2 expressed in muscles controlling retraction and protraction. Using high-speed videography in anesthetized mice, we characterize the amplitude of whisker protractions evoked by varying the intensity, duration, and frequency of optogenetic stimulation. Recordings from primary somatosensory cortex (S1) in anesthetized mice indicated that optogenetic whisker pad stimulation evokes robust yet longer latency responses than mechanical whisker stimulation. In head-fixed mice trained to report optogenetic whisker pad stimulation, psychometric curves showed similar dependence on stimulus duration as evoked whisker movements and S1 activity. Furthermore, optogenetic stimulation of S1 in expert mice was sufficient to substitute for peripheral stimulation. We conclude that whisker protractions evoked by optogenetic activation of whisker pad muscles results in cortical activity and sensory perception, consistent with the coding of evoked whisker movements by reafferent sensory input.

Controlled growth of filamentary crystals and fabrication of single-crystal whisker probes

International Nuclear Information System (INIS)

Givargizov, E. I.

2006-01-01

The growth of filamentary crystals (whiskers) on a single-crystal substrate through the vapour-liquid-solid mechanism is described. The possibility of fabricating oriented systems of whiskers on the basis of this mechanism of crystal growth is noted. A phenomenon that is important for nanotechnology is noted: the existence of a critical diameter of whiskers, below which they are not formed. The phenomenon of radial periodic instability, which is characteristic of nanowhiskers, is described and the ways of its elimination are shown. The possibility of transforming whiskers into single-crystal tips and the growth of crystalline diamond particles at their apices are noted as important for practice. Possible applications of systems of whiskers and tips are described briefly. Particular attention is paid to the latest direction in whisker technology-fabrication of single-crystal whisker probes for atomic force microscopy

Mechanical properties of molybdenum-titanium alloys micro-structurally controlled by multi-step internal nitriding

International Nuclear Information System (INIS)

Nagae, M.; Yoshio, T.; Takemoto, Y.; Takada, J.; Hiraoka, Y.

2001-01-01

Internally nitrided dilute Mo-Ti alloys having a heavily deformed microstructure near the specimen surface were prepared by a novel two-step nitriding process at 1173 to 1773 K in N 2 gas. For the nitrided specimens three-point bend tests were performed at temperatures from 77 to 298 K in order to investigate the effect of microstructure control by internal nitriding on the ductile-to-brittle transition temperature (DBTT) of the alloy Yield strength obtained at 243 K of the specimen maintaining the deformed microstructure by the two-step nitriding was about 1.7 times as much as recrystallized specimen. The specimen subjected to the two-step nitriding was bent more than 90 degree at 243 K, whereas recrystallized specimen was fractured after showing a slight ductility at 243 K. DBTT of the specimen subjected to the two-step nitriding and recrystallized specimen was about 153 K and 203 K, respectively. These results indicate that multi-step internal nitriding is very effective to the improvement in the embrittlement by the recrystallization of molybdenum alloys. (author)

Fibre laser nitriding of titanium and its alloy in open atmosphere for orthopaedic implant applications: Investigations on surface quality, microstructure and tribological properties

DEFF Research Database (Denmark)

Chan, Chi-Wai; Lee, Seunghwan; Smith, Graham C.

2017-01-01

surfaces, such as the tapered surfacein a femoral stemor the ball-shaped surface in a femoral head. To tackle this problem, a direct laser nitridingprocess in open atmosphere was performed on commercially pure titanium (grade 2, TiG2) and Ti6Al4V alloy(grade 5, TiG5) using a continuous-wave (CW) fibre...... distribution of wear debris, were carefully characterized and compared. The experimental resultsshowed that TiG2 and TiG5 reacted differently with the laser radiation at 1.06 μm wavelength in laser nitridingas evidenced by substantial differences in the microstructure, and surface colour and morphology....... Furthermore,both friction andwear properties were strongly affected by the hardness and microstructure of titaniumsamplesand direct laser nitriding led to substantial improvements in their wear resistant properties. Between the twotypes of titanium samples, bare TiG2 showed higher friction forces and wear...

Quantifying the Effect of Stress on Sn Whisker Nucleation Kinetics

Science.gov (United States)

Chason, Eric; Vasquez, Justin; Pei, Fei; Jain, Nupur; Hitt, Andrew

2018-01-01

Although Sn whiskers have been studied extensively, there is still a need to understand the driving forces behind whisker nucleation and growth. Many studies point to the role of stress, but confirming this requires a quantitative comparison between controlled stress and the resulting whisker evolution. Recent experimental studies applied stress to a Sn layer via thermal cycling and simultaneously monitored the evolution of the temperature, stress and number of nuclei. In this work, we analyze these nucleation kinetics in terms of classical nucleation theory to relate the observed behavior to underlying mechanisms including a stress dependent activation energy and a temperature and stress-dependent whisker growth rate. Non-linear least squares fitting of the data taken at different temperatures and strain rates to the model shows that the results can be understood in terms of stress decreasing the barrier for whisker nucleation.

Microstructure and fracture in SiC whisker reinforced 2124 aluminum composite

Science.gov (United States)

Nieh, T. G.; Raninen, R. A.; Chellman, D. J.

1985-01-01

The microstructures of extruded and hot-rolled 2124 Al-15 percent (by weight) SiC whisker composites have been investigated, experimentally. Among the specific factors studied were: the strength of the whisker-matrix interfaces; (2) the presence of oxides; (3) the presence of defective whiskers; (4) and the presence of distribution of intermetallic compounds, impurities in the SiC(w) powder, and microstructural inhomogeneities. Modifications in the microstructure of the SiC/AL composites due to hot rolling and extrusion are illustrated in a series of microphotographs. It was found that hot rolling along the axis of extrusion was associated with some types of whisker damage, while the whiskers still retain their original orientation. Hot-rolling perpendicular to the axis of extrusion, however, tended to rotate the whiskers and produced a nearly isotropic material. Whisker free zones were virtually eliminated or reduced in size by hot rolling. In situ Auger fractography of the composite showed that the interfacial bonding between the SiC and the Al matrix was good and that Al2O2 had no significant influence on the fracture mechanics of the composite.

Understanding and predicting metallic whisker growth and its effects on reliability : LDRD final report.

Energy Technology Data Exchange (ETDEWEB)

Michael, Joseph Richard; Grant, Richard P.; Rodriguez, Mark Andrew; Pillars, Jamin; Susan, Donald Francis; McKenzie, Bonnie Beth; Yelton, William Graham

2012-01-01

Tin (Sn) whiskers are conductive Sn filaments that grow from Sn-plated surfaces, such as surface finishes on electronic packages. The phenomenon of Sn whiskering has become a concern in recent years due to requirements for lead (Pb)-free soldering and surface finishes in commercial electronics. Pure Sn finishes are more prone to whisker growth than their Sn-Pb counterparts and high profile failures due to whisker formation (causing short circuits) in space applications have been documented. At Sandia, Sn whiskers are of interest due to increased use of Pb-free commercial off-the-shelf (COTS) parts and possible future requirements for Pb-free solders and surface finishes in high-reliability microelectronics. Lead-free solders and surface finishes are currently being used or considered for several Sandia applications. Despite the long history of Sn whisker research and the recently renewed interest in this topic, a comprehensive understanding of whisker growth remains elusive. This report describes recent research on characterization of Sn whiskers with the aim of understanding the underlying whisker growth mechanism(s). The report is divided into four sections and an Appendix. In Section 1, the Sn plating process is summarized. Specifically, the Sn plating parameters that were successful in producing samples with whiskers will be reviewed. In Section 2, the scanning electron microscopy (SEM) of Sn whiskers and time-lapse SEM studies of whisker growth will be discussed. This discussion includes the characterization of straight as well as kinked whiskers. In Section 3, a detailed discussion is given of SEM/EBSD (electron backscatter diffraction) techniques developed to determine the crystallography of Sn whiskers. In Section 4, these SEM/EBSD methods are employed to determine the crystallography of Sn whiskers, with a statistically significant number of whiskers analyzed. This is the largest study of Sn whisker crystallography ever reported. This section includes a

A radial map of multi-whisker correlation selectivity in the rat barrel cortex.

Science.gov (United States)

Estebanez, Luc; Bertherat, Julien; Shulz, Daniel E; Bourdieu, Laurent; Léger, Jean-François

2016-11-21

In the barrel cortex, several features of single-whisker stimuli are organized in functional maps. The barrel cortex also encodes spatio-temporal correlation patterns of multi-whisker inputs, but so far the cortical mapping of neurons tuned to such input statistics is unknown. Here we report that layer 2/3 of the rat barrel cortex contains an additional functional map based on neuronal tuning to correlated versus uncorrelated multi-whisker stimuli: neuron responses to uncorrelated multi-whisker stimulation are strongest above barrel centres, whereas neuron responses to correlated and anti-correlated multi-whisker stimulation peak above the barrel-septal borders, forming rings of multi-whisker synchrony-preferring cells.

Numerical study of whisker field lines in the periphery of the Large Helical Device

International Nuclear Information System (INIS)

Akao, Hideki

1990-01-01

The behavior of periphery magnetic field lines in the standard Large-Helical Device (l=2 heliotron/torsatron type) configuration is studied numerically. Three different types of behavior are found, corresponding to three different regions: the stochastic region near the outermost magnetic surface, the whisker region, and the inter-whisker region outside the stochastic region. The behavior of whisker and inter-whisker field lines is specifically analyzed. It is found that whisker field lines exhibit both regular and irregular types of behavior, whereas inter-whisker field lines exhibit only regular behavior. The connection lengths for the whisker field lines are usually as long as several tens of toroidal pitches, whereas those for the inter-whisker field lines are usually less than ten toroidal pitch lengths. Whisker field lines are characterized by three fundamental processes; stretching, folding, and nesting associated with the motion of a residual X-point of the separatrix. Simple modeling is performed to reproduce these three fundamental processes. (author)

Titanium nitride films for micro-supercapacitors: Effect of surface chemistry and film morphology on the capacitance

Science.gov (United States)

Achour, Amine; Porto, Raul Lucio; Soussou, Mohamed-Akram; Islam, Mohammad; Boujtita, Mohammed; Aissa, Kaltouma Ait; Le Brizoual, Laurent; Djouadi, Abdou; Brousse, Thierry

2015-12-01

Electrochemical capacitors (EC) in the form of packed films can be integrated in various electronic devices as power source. A fabrication process of EC electrodes, which is compatible with micro-fabrication, should be addressed for practical applications. Here, we show that titanium nitride films with controlled porosity can be deposited on flat silicon substrates by reactive DC-sputtering for use as high performance micro-supercapacitor electrodes. A superior volumetric capacitance as high as 146.4 F cm-3, with an outstanding cycling stability over 20,000 cycles, was measured in mild neutral electrolyte of potassium sulfate. The specific capacitance of the films as well as their capacitance retentions were found to depend on thickness, porosity and surface chemistry of electrodes. The one step process used to fabricate these TiN electrodes and the wide use of this material in the field of semiconductor technology make it promising for miniaturized energy storage systems.

Microwave absorption behaviors of tetra-needle-like ZnO whiskers

International Nuclear Information System (INIS)

Zhou Zuowan; Chu Longsheng; Hu Shuchun

2006-01-01

A novel type of microwave absorption coating was prepared using tetra-needle-like zinc oxide whiskers as the main functional agent. The results of the experiments show that the composite coatings containing ZnO whisker appear to have good efficiency of microwave absorption, and the effect is influenced by the aspect ratio (length to diameter, L/D), the content of the T-ZnO whiskers and the resistivity of the whiskers. Microwave-heat transformation of this kind of whisker and its composite was investigated, and the results indicated that the apparent density affected the efficiency of the heat generating. The suitable value of the apparent density is 0.16-0.18 g/cm 3 . The mechanism of microwave absorption and microwave-heat transformation was explained by the semiconductive networks formed by the tetra-needle shape, diffuse reflections results from quasi-antenna, multipoles due to charge concentration and the multi-interfaces in the composites

Nitridation of vanadium by ion beam irradiation

International Nuclear Information System (INIS)

Kiuchi, Masato; Chayahara, Akiyoshi; Kinomura, Atsushi; Ensinger, Wolfgang

1994-01-01

The nitridation of vanadium by ion beam irradiation is studied by the ion implantation method and the dynamic mixing method. The nitrogen ion implantation was carried out into deposited V(110) films. Using both methods, three phases are formed, i.e. α-V, β-V 2 N, and δ-VN. Which phases are formed is related to the implantation dose or the arrival ratio. The orientation of the VN films produced by the dynamic ion beam mixing method is (100) and that of the VN films produced by the ion implantation method is (111). The nitridation of vanadium is also discussed in comparison with that of titanium and chromium. ((orig.))

Development of new ferritic alloys reinforced by nano titanium nitrides

International Nuclear Information System (INIS)

Mathon, M.H.; Perrut, M.; Poirier, L.; Ratti, M.; Hervé, N.; Carlan, Y. de

2015-01-01

Nano-reinforced steels are considered for future nuclear reactors or for application at high temperature like the heat exchangers tubes or plates. Oxide Dispersion Strengthened (ODS) alloys are the most known of the nano-reinforced alloys. They exhibit high creep strength as well as high resistance to radiation damage. This article deals with the development of new nano reinforced alloys called Nitride Dispersed Strengthened (NDS). Those are also considered for nuclear applications and could exhibit higher ductility with a simplest fabrication way. Two main fabrication routes were studied: the co-milling of Fe–18Cr1W0.008N and TiH 2 powders and the plasma nitration at low temperature of a Fe–18Cr1W0.8Ti powder. The materials were studied mainly by Small Angle Neutron Scattering. The feasibility of the reinforcement by nano-nitride particles is demonstrated. The final size of the nitrides can be similar (few nanometers) to the nano-oxides observed in ODS alloys. The mechanical properties of the new NDS show an amazing ductility at high temperature for a nano-reinforced alloy

Development of new ferritic alloys reinforced by nano titanium nitrides

Energy Technology Data Exchange (ETDEWEB)

Mathon, M.H., E-mail: marie-helene.mathon@cea.fr [Laboratoire Léon Brillouin, CEA-CNRS, CEA/Saclay, 91191 Gif-sur-Yvette (France); Perrut, M., E-mail: mikael.perrut@onera.fr [Laboratoire Léon Brillouin, CEA-CNRS, CEA/Saclay, 91191 Gif-sur-Yvette (France); Poirier, L., E-mail: poirier@nitruvid.com [Bodycote France and Belgium, 9 r Jean Poulmarch, 95100 Argenteuil (France); Ratti, M., E-mail: mathieu.ratti@snecma.fr [CEA, DEN, Service de Recherches Métallurgiques Appliquées, F91191 Gif-sur-Yvette (France); Hervé, N., E-mail: nicolas.herve@cea.fr [CEA, DRT, LITEN, F38054 Grenoble (France); Carlan, Y. de, E-mail: yann.decarlan@cea.fr [CEA, DEN, Service de Recherches Métallurgiques Appliquées, F91191 Gif-sur-Yvette (France)

2015-01-15

Nano-reinforced steels are considered for future nuclear reactors or for application at high temperature like the heat exchangers tubes or plates. Oxide Dispersion Strengthened (ODS) alloys are the most known of the nano-reinforced alloys. They exhibit high creep strength as well as high resistance to radiation damage. This article deals with the development of new nano reinforced alloys called Nitride Dispersed Strengthened (NDS). Those are also considered for nuclear applications and could exhibit higher ductility with a simplest fabrication way. Two main fabrication routes were studied: the co-milling of Fe–18Cr1W0.008N and TiH{sub 2} powders and the plasma nitration at low temperature of a Fe–18Cr1W0.8Ti powder. The materials were studied mainly by Small Angle Neutron Scattering. The feasibility of the reinforcement by nano-nitride particles is demonstrated. The final size of the nitrides can be similar (few nanometers) to the nano-oxides observed in ODS alloys. The mechanical properties of the new NDS show an amazing ductility at high temperature for a nano-reinforced alloy.

Synthesis of whiskers of SiC microwave assisted; Sintesis de whiskers de SiC asistida por microondas

Energy Technology Data Exchange (ETDEWEB)

Garza-Mendez, F. J.; Vanegas, A. J.; Vazquez, B. A.; Garza-Paz, J.

2013-06-01

We developed a new process for the synthesis of SiC whiskers assisted by microwaves; this is based on the mixture of silica xerogels and graphite powder. As energy source were used microwaves of 2.45 GHz and 1.0 kW of power RMS. On the other hand, mesoporous silica was synthesized via sol-gel, the precursors used were TEOS/H{sub 2}O and ethanol. Through analysis of the BET is determined the value of average pore size (3.0 nm) and the surface area (1090 m2/g).By mean of X-Ray diffraction it was demonstrated that the silica obtained is an amorphous solid and, the powders obtained in the microwave synthesis are {beta}-SiC. Synthesized SiC powders were observed using a SEM in secondary electron mode, it was observed that this powders consists of SiC whiskers. The effect of microwaves on the synthesis of whiskers of SiC is discussed in the present work. (Author) 19 refs.

Ternary nanocomposite of polyaniline/manganese dioxide/titanium nitride nanowire array for supercapacitor electrode

International Nuclear Information System (INIS)

Xia, Chi; Xie, Yibing; Du, Hongxiu; Wang, Wei

2015-01-01

The electroactive polyaniline (PANI) and manganese oxide (MnO 2 ) were integrated with titanium nitride (TiN) nanowire array (NWA) to form PANI/MnO 2 /TiN ternary nanocomposite for supercapacitor application. TiN NWA was prepared via a seed-assisted hydrothermal synthesis and ammonia nitridization process. The electroactive MnO 2 and PANI was layer-by-layer coated on TiN NWA to form heterogeneous coaxial structure through a stepwise electrodeposition process. Scanning electron micrographs revealed that the well-separated TiN NWA was composed of well-distributed nanowires with diameters in the range of 10–30 nm and a total length of 1.5 μm. A villiform MnO 2 layer with a thickness of 10–20 nm covered on TiN NWA to form MnO 2 /TiN NWA composite. The coral-like PANI layer with thicknesses in the range of 20–50 nm covered on the above MnO 2 /TiN NWA to form PANI/MnO 2 /TiN NWA. Electrochemical measurements showed that a high specific capacitance of 674 F g −1 at a current density of 1 A g −1 (based on total mass of PANI/MnO 2 ) was obtained for PANI/MnO 2 /TiN NWA ternary nanocomposite, which was much higher than that of PANI/MnO 2 /carbon-cloth composites reported previously. This ternary nanocomposite also showed a good rate and cycling stability. Moreover, in comparison with PANI/TiN NWA or MnO 2 /TiN NWA, the specific capacitance of PANI/MnO 2 /TiN NWA was obviously enhanced due to the extra pseudocapacitance contribution and the effective surface area of coral-like PANI layer, showing the advantage of manipulating the heterogeneous coaxial configuration between PANI and MnO 2 for fundamentally improved capacitive performance. These results demonstrated that PANI/MnO 2 /TiN NWA ternary nanocomposite was a promising candidate electrode material for supercapacitor application

Characterization of TiN, TiC and Ti(C,N) in titanium-alloyed ferritic chromium steels focusing on the significance of different particle morphologies

Energy Technology Data Exchange (ETDEWEB)

Michelic, S.K., E-mail: susanne.michelic@unileoben.ac.at [Chair of Ferrous Metallurgy, Montanuniversitaet Leoben, Franz-Josef-Straße 18, 8700 Leoben (Austria); Loder, D. [Chair of Ferrous Metallurgy, Montanuniversitaet Leoben, Franz-Josef-Straße 18, 8700 Leoben (Austria); Reip, T.; Ardehali Barani, A. [Outokumpu Nirosta GmbH, Essener Straße 244, 44793 Bochum (Germany); Bernhard, C. [Chair of Ferrous Metallurgy, Montanuniversitaet Leoben, Franz-Josef-Straße 18, 8700 Leoben (Austria)

2015-02-15

Titanium-alloyed ferritic chromium steels are a competitive option to classical austenitic stainless steels owing to their similar corrosion resistance. The addition of titanium significantly influences their final steel cleanliness. The present contribution focuses on the detailed metallographic characterization of titanium nitrides, titanium carbides and titanium carbonitrides with regard to their size, morphology and composition. The methods used are manual and automated Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy as well as optical microscopy. Additional thermodynamic calculations are performed to explain the precipitation procedure of the analyzed titanium nitrides. The analyses showed that homogeneous nucleation is decisive at an early process stage after the addition of titanium. Heterogeneous nucleation gets crucial with ongoing process time and essentially influences the final inclusion size of titanium nitrides. A detailed investigation of the nuclei for heterogeneous nucleation with automated Scanning Electron Microscopy proved to be difficult due to their small size. Manual Scanning Electron Microscopy and optical microscopy have to be applied. Furthermore, it was found that during solidification an additional layer around an existing titanium nitride can be formed which changes the final inclusion morphology significantly. These layers are also characterized in detail. Based on these different inclusion morphologies, in combination with thermodynamic results, tendencies regarding the formation and modification time of titanium containing inclusions in ferritic chromium steels are derived. - Graphical abstract: Display Omitted - Highlights: • The formation and modification of TiN in the steel 1.4520 was examined. • Heterogeneous nucleation essentially influences the final steel cleanliness. • In most cases heterogeneous nuclei in TiN inclusions are magnesium based. • Particle morphology provides important information

Impedance study on the corrosion of PVD and CVD titanium nitride coatings

International Nuclear Information System (INIS)

Elsener, B.; Rota, A.; Boehni, H.

1989-01-01

Titanium nitride (TiN) coatings, produced by physical (PVD) or chemical (CVD) vapor deposition techniques are used routinely to improve the wear and corrosion resistance of a surface. The main problem in using TiN as a protective coating in aggressive environements are pores and pinholes in the coating where the substrate is exposed to the electrolyte. In this work, the electrochemical and corrosion behaviour of TiN films on quartz glass, carbon steel, 304 and 316 stainless steel is studied by polarization curves and electrochemical impedance spectroscopy (EIS) in hydrochloric acid. It is shown that the TiN coating can be used successfully only on substrates that passivate easily. On mild steel rapid corrosion takes place at pores in the coating due to the very noble steady state potential of the TiN coating. The interaction of the metallic substrate with the TiN coating is discussed for the two limiting cases mild steel (active) and 316SS (passive). It is shown that the determination of the coating porosity is possible for the active substrate only. On the passive substrate the occurence of an additional time constant in the high frequency region of the spectrum qualitatively indicates the presence of pores. A quality control of the coatings based on this fact might be possible. (author) 15 refs., 6 figs., 2 tabs

Electrophysiological performance of a bipolar membrane-coated titanium nitride electrode: a randomized comparison of steroid and nonsteroid lead designs.

Science.gov (United States)

Wiegand, U K; Zhdanov, A; Stammwitz, E; Crozier, I; Claessens, R J; Meier, J; Bos, R J; Bode, F; Potratz, J

1999-06-01

The aim of this multicenter study was to investigate the performance of a new cardiac pacemaker lead with a titanium nitride cathode coated with a copolymer membrane. In particular, the electrophysiological effect of steroid dissolved in this ion-exchange membrane was evaluated by randomized comparison. Ninety-five patients were randomized either to the 1450 T (n = 51) or the 1451 T ventricular lead (n = 45) and received telemeteral VVI(R) pacemakers with identical diagnostic features. Both leads were bipolar, were passively affixed, and had a porous titanium nitride tip with a surface area of 3.5 mm2. The only difference between the two electrodes was 13 micrograms of dexamethasone added to the 1450 Ts membrane coating. Voltage thresholds (VTH) at pulse durations of 0.25, 0.37, and 0.5 ms, lead impedance, and sensing thresholds were measured at discharge, 2 weeks, 1 month, 3 months, and 6 months after implantation. Mean amplitude and the slew rate from three telemetered intracardiac electrograms, chronaxie-rheobase product, and minimum energy consumption were calculated. After a 6-month follow-up, mean voltage thresholds of 0.65 +/- 0.20 V and 0.63 +/- 0.34 were achieved for the 1450 T lead and 1451 T lead, respectively. As a result, a VTH < 1.0 V was obtained in all patients with 1450 T electrodes and in 97.7% of patients with 1451 T leads after 6 months follow-up. In both electrodes, stable VTH was reached 2 weeks after implantation, and no transient rise in threshold was observed. No differences were observed between the steroid and the nonsteroid group in respect to VTH, chronaxie-rheobase product, minimum energy consumption, and potential amplitude and slew rate. In conclusion, safe and efficient pacing at low pulse amplitudes were achieved with both leads. The tip design, independently of the steroid additive, prevented any energy-consuming increases in the voltage threshold.

Synthesis and growth mechanisms of ZrC whiskers fabricated by a VLS process

Energy Technology Data Exchange (ETDEWEB)

Lee, Dongju [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of). Nuclear Materials Development Division; Song, Sung Ho [Kongju National Univ., Chungnam (Korea, Republic of). Division of Advanced Materials Engineering

2017-08-15

The mechanisms of nano-sized ZrC whisker formation by a vapor-liquid-solid process (VLS) are investigated, which produces a very high purity, single crystal whisker. Rectangular ZrC whiskers with a cross-sectional diameter of 100-200 nm and lengths up to tens of microns are formed under the catalytic effect of nickel. The ZrC whiskers are characterized using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. ZrC whiskers can be used as a potential reinforcing and strengthening phase for ceramic composites.

Fabrication of α-chitin whisker-reinforced poly(vinyl alcohol) nanocomposite nanofibres by electrospinning

International Nuclear Information System (INIS)

Junkasem, Jirawut; Rujiravanit, Ratana; Supaphol, Pitt

2006-01-01

The present contribution reports, for the first time, the successful fabrication of α-chitin whisker-reinforced poly(vinyl alcohol) (PVA) nanocomposite nanofibres by electrospinning. The α-chitin whiskers were prepared from α-chitin flakes from shrimp shells by acid hydrolysis. The as-prepared chitin whiskers exhibited lengths in the range 231-969 nm and widths in the range 12-65 nm, with the average length and width being about 549 and 31 nm, respectively. Successful incorporation of the chitin whiskers within the as-spun PVA/chitin whisker nanocomposite nanofibres was verified by infrared spectroscopic and thermogravimetric methods. The incorporation of chitin whiskers within the as-spun nanocomposite fibre mats increased the Young's modulus by about 4-8 times over that of the neat as-spun PVA fibre mat

Calcium silicate ceramic scaffolds toughened with hydroxyapatite whiskers for bone tissue engineering

International Nuclear Information System (INIS)

Feng, Pei; Wei, Pingpin; Li, Pengjian; Gao, Chengde; Shuai, Cijun; Peng, Shuping

2014-01-01

Calcium silicate possessed excellent biocompatibility, bioactivity and degradability, while the high brittleness limited its application in load-bearing sites. Hydroxyapatite whiskers ranging from 0 to 30 wt.% were incorporated into the calcium silicate matrix to improve the strength and fracture resistance. Porous scaffolds were fabricated by selective laser sintering. The effects of hydroxyapatite whiskers on the mechanical properties and toughening mechanisms were investigated. The results showed that the scaffolds had a uniform and continuous inner network with the pore size ranging between 0.5 mm and 0.8 mm. The mechanical properties were enhanced with increasing hydroxyapatite whiskers, reached a maximum at 20 wt.% (compressive strength: 27.28 MPa, compressive Young's modulus: 156.2 MPa, flexural strength: 15.64 MPa and fracture toughness: 1.43 MPa·m 1/2 ) and then decreased by addition of more hydroxyapatite whiskers. The improvement of mechanical properties was due to whisker pull-out, crack deflection and crack bridging. Moreover, the degradation rate decreased with the increase of hydroxyapatite whisker content. A layer of bone-like apatite was formed on the scaffold surfaces after being soaked in simulated body fluid. Human osteoblast-like MG-63 cells spread well on the scaffolds and proliferated with increasing culture time. These findings suggested that the calcium silicate scaffolds reinforced with hydroxyapatite whiskers showed great potential for bone regeneration and tissue engineering applications. - Highlights: • HA whiskers were incorporated into CS to improve the properties. • The scaffolds were successfully fabricated by SLS. • Toughening mechanisms was whisker pull-out, crack deflection and bridging. • The scaffolds showed excellent apatite forming ability

Calcium silicate ceramic scaffolds toughened with hydroxyapatite whiskers for bone tissue engineering

Energy Technology Data Exchange (ETDEWEB)

Feng, Pei [State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, PR China, (China); Wei, Pingpin [Cancer Research Institute, Central South University, Changsha 410078 (China); Li, Pengjian; Gao, Chengde [State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, PR China, (China); Shuai, Cijun, E-mail: shuai@csu.edu.cn [State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, PR China, (China); Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC 29425 (United States); Peng, Shuping, E-mail: shuping@csu.edu.cn [Cancer Research Institute, Central South University, Changsha 410078 (China)

2014-11-15

Calcium silicate possessed excellent biocompatibility, bioactivity and degradability, while the high brittleness limited its application in load-bearing sites. Hydroxyapatite whiskers ranging from 0 to 30 wt.% were incorporated into the calcium silicate matrix to improve the strength and fracture resistance. Porous scaffolds were fabricated by selective laser sintering. The effects of hydroxyapatite whiskers on the mechanical properties and toughening mechanisms were investigated. The results showed that the scaffolds had a uniform and continuous inner network with the pore size ranging between 0.5 mm and 0.8 mm. The mechanical properties were enhanced with increasing hydroxyapatite whiskers, reached a maximum at 20 wt.% (compressive strength: 27.28 MPa, compressive Young's modulus: 156.2 MPa, flexural strength: 15.64 MPa and fracture toughness: 1.43 MPa·m{sup 1/2}) and then decreased by addition of more hydroxyapatite whiskers. The improvement of mechanical properties was due to whisker pull-out, crack deflection and crack bridging. Moreover, the degradation rate decreased with the increase of hydroxyapatite whisker content. A layer of bone-like apatite was formed on the scaffold surfaces after being soaked in simulated body fluid. Human osteoblast-like MG-63 cells spread well on the scaffolds and proliferated with increasing culture time. These findings suggested that the calcium silicate scaffolds reinforced with hydroxyapatite whiskers showed great potential for bone regeneration and tissue engineering applications. - Highlights: • HA whiskers were incorporated into CS to improve the properties. • The scaffolds were successfully fabricated by SLS. • Toughening mechanisms was whisker pull-out, crack deflection and bridging. • The scaffolds showed excellent apatite forming ability.

The development of SiC whisker fabrication technology for nuclear applications

International Nuclear Information System (INIS)

Kang, Thae Khapp; Kuk, Il Hiun; Lee, Jae Chun; Rhee, Chang Kyu; Lee, Ho Jin; Park, Soon Dong

1990-02-01

Important process factors of carbothermic process for the growth of SiC whiskers were investigated. The crystalline form of silicon dioxide, amount of carbon addition, graphite, silicon, catalysts, additive and reaction temperature were chosen as the main factors. Morphology of the resultant products was grouped into 3 different types; whisker,noodle and power types. The addition of catalyst affected in most the formation of SiC whiskers. Effects of catalyst and additive additions and reaction atmospheres on the morphology anf growth of SiC whiskers were investigated, silicon monoxide power and carbon monoxide gas were used as the raw materials. The addition of an iron containing catalyst resulted in a very long thread-like growth of the whiskers, while that of sodium chloride helical curlings. Addition of hydrogen to the non-oxidizing atmosphere enhanced the whisker formations. Crystallization of amorphous silicon monoxide raw powder was investigated at high temperatures up to 1500 deg C in Ar atmosphere using graphite crucible. Up to 900 deg C no crystallization occurred, while at 1100 - 1300 deg C silicon formation, and at 1500 deg C silicon dioxide and silicon carbide formations were detected. A slight weight loss began 1300 deg C, and the weight loss became about 33 % at 1500 deg C. After the formation reaction of SiC whiskers, the reaction products were leached by hydrofluoric acids. The optimum concentration of the hydrofluoric acid was 2 %. (author)

Nanoreinforced biocompatible hydrogels from wood hemicelluloses and cellulose whiskers

Science.gov (United States)

Muzaffer Ahmet Karaaslan; Mandla A. Tshabalala; Daniel J. Yelle; Gisela Buschle-Diller

2011-01-01

Nanoreinforced hydrogels with a unique network structure were prepared from wood cellulose whiskers coated with chemically modified wood hemicelluloses. The hemicelluloses were modified with 2-hydroxyethylmethacrylate prior to adsorption onto the cellulose whiskers in aqueous medium. Synthesis of the hydrogels was accomplished by in situ radical polymerization of the...

Kinetic modelling of chlorination of nitrided ilmenite using MATLAB

Energy Technology Data Exchange (ETDEWEB)

Ramakrishnan, Sivakumar, E-mail: srsivakumar@usm.my; Kwok, Teong Chen, E-mail: ctck@live.com; Hamid, Sheikh Abdul Rezan Sheikh Abdul, E-mail: rezanshk@gmail.com [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300, Nibong Tebal, Penang (Malaysia)

2016-07-19

In the present study, chlorination of nitride ilmenite using 2{sup k} factorial design was investigated. The reduction experiments were carried out in a temperature range of 400°C to 500°C, chlorination duration from 1 hour to 3 hours and using different type of carbon reactant. Phases of raw materials and reduced samples were analyzed by X-ray diffraction (XRD). Ilmenite was reduced to TiO{sub x}C{sub y}N{sub z} through carbothermal and nitridation for further chlorination into titanium tetrachloride. The Design of Experiment analysis suggested that the types of carbon reactant contribute most influence to the extent of chlorination of nitride ilmenite. The extent of chlorination was highest at 500°C with 3 hours chlorination time and carbon nanotube as carbon reactant.

Effect of TiC whisker addition on properties of YG1OF alloy

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

The cemented carbide material (YG10F) with different additions of TiC whisker (0%, 0.3%, 0.6%, mass fraction) was prepared by different techniques. The effect of TiC whisker addition on the density, microhardness and toughness of the experimental material was investigated. The results indicate that after the wet-milling for 8 h and sintering in vacuum at 1 440 ℃, the toughness of YG10F is remarkably improved and meanwhile higher microhardness is obtained by 0.3% TiC whisker addition. Preliminary analysis suggests that the main toughening mechanism of TiC whisker in YG10F is whisker pull-out and bridging phenomena.

Muscular Basis of Whisker Torsion in Mice and Rats.

Science.gov (United States)

Haidarliu, Sebastian; Bagdasarian, Knarik; Shinde, Namrata; Ahissar, Ehud

2017-09-01

Whisking mammals move their whiskers in the rostrocaudal and dorsoventral directions with simultaneous rolling about their long axes (torsion). Whereas muscular control of the first two types of whisker movement was already established, the anatomic muscular substrate of the whisker torsion remains unclear. Specifically, it was not clear whether torsion is induced by asymmetrical operation of known muscles or by other largely unknown muscles. Here, we report that mystacial pads of newborn and adult rats and mice contain oblique intrinsic muscles (OMs) that connect diagonally adjacent vibrissa follicles. Each of the OMs is supplied by a cluster of motor end plates. In rows A and B, OMs connect the ventral part of the rostral follicle with the dorsal part of the caudal follicle. In rows C-E, in contrast, OMs connect the dorsal part of the rostral follicle to the ventral part of the caudal follicle. This inverse architecture is consistent with previous behavioral observations [Knutsen et al.: Neuron 59 (2008) 35-42]. In newborn mice, torsion occurred in irregular single twitches. In adult anesthetized rats, microelectrode mediated electrical stimulation of an individual OM that is coupled with two adjacent whiskers was sufficient to induce a unidirectional torsion of both whiskers. Torsional movement was associated with protracting movement, indicating that in the vibrissal system, like in the ocular system, torsional movement is mechanically coupled to horizontal and vertical movements. This study shows that torsional whisker rotation is mediated by specific OMs whose morphology and attachment sites determine rotation direction and mechanical coupling, and motor innervation determines rotation dynamics. Anat Rec, 300:1643-1653, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

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.

Tin Whisker Formation — A Stress Relieve Phenomenon

Science.gov (United States)

Dittes, M.; Oberndorff, P.; Crema, P.; Su, P.

2006-02-01

With the move towards lead-free electronics also the solderable finish of electronic components' terminations are converted. While the typical finish was containing 5 % to 20 % lead (Pb) and thus was almost whisker free, lead (Pb)-free finishes such as pure tin or high tin alloys are rather prone to grow whisker. These whiskers are spontaneous protrusions that grow to a significant length of up to millimeters with a typical diameter in the range of few microns and are suspect to cause shorts in electronic assemblies. The latest details of the mechanisms are not yet understood. However it appears to be well established that the driving force for tin whisker growth is a compressive stress in the tin layer and that this stress is released by whisker formation. Besides the mechanism for whisker growth therefore the mechanism of the stress induction is of interest. The origin of that stress may have multiple sources. Among others the most important one is the volume increase within the tin layer due the formation of intermetallics at the interface to the base material. This applies to all copper based material. For base materials with a coefficient of thermal expansion (cte) significantly different from the tin finish another mechanism plays the dominant role. This is the induction of stress during thermal cycling due to the different expansion of the materials with every temperature change. Another mechanism for stress induction may be the oxidation of the finish, which also leads to a local volume increase. Based on the knowledge of stress induction various mitigation strategies can be deducted. Most common is the introduction of a diffusion barrier (e.g. Ni) in order to prevent the growth of the Cu-Sn intermetallics, the controlled growth of Cu-Sn intermetallics in order to prevent their irregularity or the introduction of a mechanical buffer material targeting at the minimisation of the cte mismatch between base and finish material. With respect to the stress

Characteristics of the epitaxy of InGaN-based light-emitting diodes grown by nanoscale epitaxial lateral overgrowth using a nitrided titanium buffer layer

International Nuclear Information System (INIS)

Shieh, Chen-Yu; Li, Zhen-Yu; Chang, Jenq-Yang; Chi, Gou-Chung

2015-01-01

In this work, a buffer layer of nitrided titanium (Ti) achieved through the nitridation of a Ti metal layer on a sapphire substrate was used for the epitaxial growth of InGaN-based light-emitting diodes (LEDs) achieved by low pressure metal-organic chemical vapor deposition. The effect of in-situ Ti metal nitridation on the performance of these InGaN-based LEDs was then investigated. It was very clear that the use of the nitrided Ti buffer layer (NTBL) induced the formation of a nanoscale epitaxial lateral overgrowth layer during the epitaxial growth. When evaluated by Raman spectroscopy, this epi-layer exhibited large in-plane compressive stress releasing with a Raman shift value of 567.9 cm -1 . Cathodoluminescence spectroscopy and transmission electron microscopy results indicated that the InGaN-based LEDs with an NTBL have improved crystal quality, with a low threading dislocations density being yielded via the strain relaxation in the InGaN-based LEDs. Based on the results mentioned above, the electroluminescence results indicate that the light performance of InGaN-based LEDs with an NTBL can be enhanced by 45% and 42% at 20 mA and 100 mA, respectively. These results suggest that the strain relaxation and quality improvement in the GaN epilayer could be responsible for the enhancement of emission power. - Highlights: • The crystal-quality of InGaN-based LEDs with NTBL by NELOG was improved. • The InGaN-based LEDs with NTBL have strain releases by NELOG. • The optical properties of InGaN-based LEDs were shown by CL and EL measurements

Effect of linear alcohol molecular size on the self-assembly of fullerene whiskers

International Nuclear Information System (INIS)

Amer, Maher S.; Todd, T. Kyle; Busbee, John D.

2011-01-01

Highlights: → The longer the alcohol molecule, the shorter the length of the assembled whisker. → Interaction between alcohol and fullerene solvent is the key factor. → The stronger the alcohol/solvent interaction, the longer the whisker. - Abstract: The recent development of self-assembled fullerene whiskers and wires has created an enormous potential and resolved a serious challenge for utilizing such unique class of carbon material in advanced nano-scale, molecular-based electronic, optical, and thermal devices. In this paper we investigate, the self-assembly of C 60 molecules into one-dimensional whiskers using a series of linear alcohols H(CH 2 ) n OH, with n changing from 1 (methanol) to 3 (isopropyl alcohol), to elucidate the effect of alcohol molecular size on the size distribution of the self-assemble fullerene whiskers. Our results show that the length of the produced fullerene whiskers is affected by the molecular size of the alcohol used in the process. The crucial role played by solvent/alcohol interaction in the assembly process is discussed. In addition, Raman spectroscopy measurements support the notion that the self-assembled whiskers are primarily held by depletion forces and no evidence of fullerene polymerization was observed.

Precision rodent whisker stimulator with integrated servo-locked control and displacement measurement.

Science.gov (United States)

Walker, Jennifer L; Monjaraz-Fuentes, Fernanda; Pedrow, Christi R; Rector, David M

2011-03-15

We developed a high speed voice coil based whisker stimulator that delivers precise deflections of a single whisker or group of whiskers in a repeatable manner. The device is miniature, quiet, and inexpensive to build. Multiple stimulators fit together for independent stimulation of four or more whiskers. The system can be used with animals under anesthesia as well as awake animals with head-restraint, and does not require trimming the whiskers. The system can deliver 1-2 mm deflections in 2 ms resulting in velocities up to 900 mm/s to attain a wide range of evoked responses. Since auditory artifacts can influence behavioral studies using whisker stimulation, we tested potential effects of auditory noise by recording somatosensory evoked potentials (SEP) with varying auditory click levels, and with/without 80 dBa background white noise. We found that auditory clicks as low as 40 dBa significantly influence the SEP. With background white noise, auditory clicks as low as 50 dBa were still detected in components of the SEP. For behavioral studies where animals must learn to respond to whisker stimulation, these sounds must be minimized. Together, the stimulator and data system can be used for psychometric vigilance tasks, mapping of the barrel cortex and other electrophysiological paradigms. Copyright © 2010 Elsevier B.V. All rights reserved.

Mystacial Whisker Layout and Musculature in the Guinea Pig (Cavia porcellus): A Social, Diurnal Mammal.

Science.gov (United States)

Grant, Robyn A; Delaunay, Mariane G; Haidarliu, Sebastian

2017-03-01

All mammals (apart from apes and humans) have whiskers that make use of a similar muscle arrangement. Whisker specialists, such as rats and mice, tend to be nocturnal and arboreal, relying on their whisker sense of touch to guide exploration around tree canopies at night. As such, nocturnal arboreal rodents have many whiskers that are organised into a grid-like pattern, and moved using a complex array of muscles. Indeed, most arboreal, nocturnal mammals tend to have specialised whiskers that are longer and arranged in a dense, regular grid, compared with terrestrial, diurnal mammals. The guinea pig diverged early from murid rodents (around 75 million years ago), and are ground-dwelling, diurnal animals. It would be predicted that, as a terrestrial mammal, they may have less whiskers and a reduced muscle architecture compared to arboreal, nocturnal rodents. We examined the mystacial whisker layout, musculature and movement capacity of Guinea pig (Cavia porcellus) whiskers and found that they did indeed have a disorganized whisker layout, with a fortification around the eye area. In addition, there was a reduction in musculature, especially in the intrinsic muscles. Despite guinea pigs not cyclically moving their whiskers, the mystacial musculature was still very similar to that of murid rodents. We suggest that the conserved presence of whisker layout and musculature, even in visual mammals such as primates and guinea pigs, may indicate that whiskers still play an important role in these animals, including protecting the eyes and being involved in tactile social behaviors. Anat Rec, 300:527-536, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Chemical vapor deposition of refractory ternary nitrides for advanced diffusion barriers

Energy Technology Data Exchange (ETDEWEB)

Custer, Jonathan S.; Fleming, James G.; Roherty-Osmun, Elizabeth; Smith, Paul Martin

1998-09-22

Refractory ternary nitride films for diffusion barriers in microelectronics have been grown using chemical vapor deposition. Thin films of titanium-silicon-nitride, tungsten-boron-nitride, and tungsten-silicon-nitride of various compositions have been deposited on 150 mm Si wafers. The microstructure of the films are either fully amorphous for the tungsten based films, or nauocrystalline TiN in an amorphous matrix for titanium-silicon-nitride. All films exhibit step coverages suitable for use in future microelectronics generations. Selected films have been tested as diffusion barriers between copper and silicon, and generally perform extremely weH. These fiIms are promising candidates for advanced diffusion barriers for microelectronics applications. The manufacturing of silicon wafers into integrated circuits uses many different process and materials. The manufacturing process is usually divided into two parts: the front end of line (FEOL) and the back end of line (BEOL). In the FEOL the individual transistors that are the heart of an integrated circuit are made on the silicon wafer. The responsibility of the BEOL is to wire all the transistors together to make a complete circuit. The transistors are fabricated in the silicon itself. The wiring is made out of metal, currently aluminum and tungsten, insulated by silicon dioxide, see Figure 1. Unfortunately, silicon will diffuse into aluminum, causing aluminum spiking of junctions, killing transistors. Similarly, during chemical vapor deposition (CVD) of tungsten from ~fj, the reactivity of the fluorine can cause "worn-holes" in the silicon, also destroying transistors. The solution to these problems is a so-called diffusion barrier, which will allow current to pass from the transistors to the wiring, but will prevent reactions between silicon and the metal.

Development of 9Al2O3{center_dot}2B2O3 whiskers reinforced piston by squeeze casting. Manufacturing process and characteristics of whiskers preform; Squeeze cast ho ni yoru 9Al2O3{center_dot}2B2O3 whisker kyoka piston no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Yamauchi, T; Suzuki, M; Takahashi, M; Takada, I; Toda, M [Suzuki Motor Co. Ltd., Shizuoka (Japan)

1997-10-01

The properties of 9Al2O3 {center_dot} 2B2O3 whisker reinforced aluminum alloy is excellent compared with conventional material at elevated temperatures. 9Al2O3 {center_dot} 2B2O3 whisker reinforced aluminum alloy was applied to the piston head of two cycle engines. This piston was produced by a squeeze casting process with the granulated whiskers preform which was infiltrated by a molten aluminum alloy under high pressure. Since the permeability of the granulated whiskers preform is larger than that of the uniform preform in which whiskers are distributed randomly and uniformly, it became possible to suppress the preform deformation using the developed preform. 7 refs., 8 figs., 2 tabs.

Ternary nanocomposite of polyaniline/manganese dioxide/titanium nitride nanowire array for supercapacitor electrode

Energy Technology Data Exchange (ETDEWEB)

Xia, Chi; Xie, Yibing, E-mail: ybxie@seu.edu.cn; Du, Hongxiu; Wang, Wei [Southeast University, School of Chemistry and Chemical Engineering (China)

2015-01-15

The electroactive polyaniline (PANI) and manganese oxide (MnO{sub 2}) were integrated with titanium nitride (TiN) nanowire array (NWA) to form PANI/MnO{sub 2}/TiN ternary nanocomposite for supercapacitor application. TiN NWA was prepared via a seed-assisted hydrothermal synthesis and ammonia nitridization process. The electroactive MnO{sub 2} and PANI was layer-by-layer coated on TiN NWA to form heterogeneous coaxial structure through a stepwise electrodeposition process. Scanning electron micrographs revealed that the well-separated TiN NWA was composed of well-distributed nanowires with diameters in the range of 10–30 nm and a total length of 1.5 μm. A villiform MnO{sub 2} layer with a thickness of 10–20 nm covered on TiN NWA to form MnO{sub 2}/TiN NWA composite. The coral-like PANI layer with thicknesses in the range of 20–50 nm covered on the above MnO{sub 2}/TiN NWA to form PANI/MnO{sub 2}/TiN NWA. Electrochemical measurements showed that a high specific capacitance of 674 F g{sup −1} at a current density of 1 A g{sup −1} (based on total mass of PANI/MnO{sub 2}) was obtained for PANI/MnO{sub 2}/TiN NWA ternary nanocomposite, which was much higher than that of PANI/MnO{sub 2}/carbon-cloth composites reported previously. This ternary nanocomposite also showed a good rate and cycling stability. Moreover, in comparison with PANI/TiN NWA or MnO{sub 2}/TiN NWA, the specific capacitance of PANI/MnO{sub 2}/TiN NWA was obviously enhanced due to the extra pseudocapacitance contribution and the effective surface area of coral-like PANI layer, showing the advantage of manipulating the heterogeneous coaxial configuration between PANI and MnO{sub 2} for fundamentally improved capacitive performance. These results demonstrated that PANI/MnO{sub 2}/TiN NWA ternary nanocomposite was a promising candidate electrode material for supercapacitor application.

Wear monitoring of protective nitride coatings using image processing

DEFF Research Database (Denmark)

Rasmussen, Inge Lise; Guibert, M.; Belin, M.

2010-01-01

-meter with up to 105 19 repetitive cycles, eventually leaving the embedded TiN signal layer uncovered at the bottom the wear scar. 20 The worn surface was characterized by subsequent image processing. A color detection of the wear scar with 21 the exposed TiN layer by a simple optical imaging system showed......A double-layer model system, consisting of a thin layer of tribological titanium aluminum nitride (TiAlN) on 17 top of titanium nitride (TiN), was deposited on polished 100Cr6 steel substrates. The TiAlN top-coatings 18 were exposed to abrasive wear by a reciprocating wear process in a linear tribo...... a significant increase up to a factor of 2 of 22 the relative color values from the TiAlN top layers to the embedded TiN signal layers. This behavior agrees 23 well with the results of reflectance detection experiment with a red laser optical system on the same system. 24 Thus we have demonstrated that image...

Structure and properties of nitrided surface layer produced on NiTi shape memory alloy by low temperature plasma nitriding

International Nuclear Information System (INIS)

Czarnowska, Elżbieta; Borowski, Tomasz; Sowińska, Agnieszka; Lelątko, Józef; Oleksiak, Justyna; Kamiński, Janusz; Tarnowski, Michał; Wierzchoń, Tadeusz

2015-01-01

Highlights: • Low temperature plasma nitriding process of NiTi shape memory alloy is presented. • The possibility of treatment details of sophisticated shape. • TiN surface layer has diffusive character. • TiN surface layer increases corrosion resistance of NiTi alloy. • Produced TiN layer modify the biological properties of NiTi alloy. - Abstract: NiTi shape memory alloys are used for bone and cardiological implants. However, on account of the metallosis effect, i.e. the release of the alloy elements into surrounding tissues, they are subjected to various surface treatment processes in order to improve their corrosion resistance and biocompatibility without influencing the required shape memory properties. In this paper, the microstructure, topography and morphology of TiN surface layer on NiTi alloy, and corrosion resistance, both before and after nitriding in low-temperature plasma at 290 °C, are presented. Examinations with the use of the potentiodynamic and electrochemical impedance spectroscopy methods were carried out and show an increase of corrosion resistance in Ringer's solution after glow-discharge nitriding. This surface titanium nitride layer also improved the adhesion of platelets and the proliferation of osteoblasts, which was investigated in in vitro experiments with human cells. Experimental data revealed that nitriding NiTi shape memory alloy under low-temperature plasma improves its properties for bone implant applications

Structure and properties of nitrided surface layer produced on NiTi shape memory alloy by low temperature plasma nitriding

Energy Technology Data Exchange (ETDEWEB)

Czarnowska, Elżbieta [Children' s Memorial Health Institute, Pathology Department, Al. Dzieci Polskich 20, 04-730 Warsaw (Poland); Borowski, Tomasz [Warsaw University of Technology, Faculty of Materials Science and Engineering, Wołoska 141, 02-507 Warsaw (Poland); Sowińska, Agnieszka [Children' s Memorial Health Institute, Pathology Department, Al. Dzieci Polskich 20, 04-730 Warsaw (Poland); Lelątko, Józef [Silesia University, Faculty of Computer Science and Materials Science, 75 Pułku Piechoty 1A, 41-500 Chorzów (Poland); Oleksiak, Justyna; Kamiński, Janusz; Tarnowski, Michał [Warsaw University of Technology, Faculty of Materials Science and Engineering, Wołoska 141, 02-507 Warsaw (Poland); Wierzchoń, Tadeusz, E-mail: twierz@inmat.pw.edu.pl [Warsaw University of Technology, Faculty of Materials Science and Engineering, Wołoska 141, 02-507 Warsaw (Poland)

2015-04-15

Highlights: • Low temperature plasma nitriding process of NiTi shape memory alloy is presented. • The possibility of treatment details of sophisticated shape. • TiN surface layer has diffusive character. • TiN surface layer increases corrosion resistance of NiTi alloy. • Produced TiN layer modify the biological properties of NiTi alloy. - Abstract: NiTi shape memory alloys are used for bone and cardiological implants. However, on account of the metallosis effect, i.e. the release of the alloy elements into surrounding tissues, they are subjected to various surface treatment processes in order to improve their corrosion resistance and biocompatibility without influencing the required shape memory properties. In this paper, the microstructure, topography and morphology of TiN surface layer on NiTi alloy, and corrosion resistance, both before and after nitriding in low-temperature plasma at 290 °C, are presented. Examinations with the use of the potentiodynamic and electrochemical impedance spectroscopy methods were carried out and show an increase of corrosion resistance in Ringer's solution after glow-discharge nitriding. This surface titanium nitride layer also improved the adhesion of platelets and the proliferation of osteoblasts, which was investigated in in vitro experiments with human cells. Experimental data revealed that nitriding NiTi shape memory alloy under low-temperature plasma improves its properties for bone implant applications.

Enhancing Mechanical and Thermal Properties of Epoxy Nanocomposites via Alignment of Magnetized SiC Whiskers.

Science.gov (United States)

Townsend, James; Burtovyy, Ruslan; Aprelev, Pavel; Kornev, Konstantin G; Luzinov, Igor

2017-07-12

This research is focused on the fabrication and properties of epoxy nanocomposites containing magnetized SiC whiskers (MSiCWs). To this end, we report an original strategy for fabrication of magnetically active SiCWs by decorating the whiskers with magnetic (iron oxide) nanoparticles via polymer-polymer (poly(acrylic acid)/poly(2-vinyl pyridine)) complexation. The obtained whiskers demonstrated a substantial magnetic response in the polymerizing epoxy resin, with application of only a 20 mT (200 G) magnetic field. We also found that the whiskers chemically reacted with the epoxy resin, causing formation of an extended interphase near the boundary of the whiskers. The SiC whiskers oriented with the magnetic field demonstrated positive effects on the behavior of epoxy-based nanocomposites. Namely, the aligned MSiCWs enhanced the thermomechanical properties of the materials significantly above that of the neat epoxy and epoxy nanocomposite, with randomly oriented whiskers.

Improved mechanical properties of hydroxyapatite whisker-reinforced poly(L-lactic acid) scaffold by surface modification of hydroxyapatite.

Science.gov (United States)

Fang, Zhou; Feng, Qingling

2014-02-01

To improve the mechanical properties of porous hydroxyapatite/poly(L-lactic acid) (HA/PLLA) composites, HA whiskers with high crystallinity and high aspect ratio were synthesized. HA whiskers were modified with γ-aminopropyltriethoxysilane (APTES) to improve the interface between HA whiskers and PLLA. The composite scaffold consists of a porous PLLA matrix with HA whiskers distributed homogeneously. The morphology and the distributions of pore sizes of PLLA scaffold was not influenced by introducing HA whiskers, while the mechanical properties were improved. Both the compressive strength and compressive modulus were increased with the weight ratio of APTES-modified HA whiskers up to 30 wt.%, but only up to 15 wt.% for non-modified HA whiskers. With more than 15 wt.% HA whiskers, the mechanical properties of HA/PLLA scaffold were better improved with APTES-modified HA whiskers than non-modified. The HA whisker/PLLA scaffold with high porosity and improved mechanical properties is attractive in the application of tissue engineering. Copyright © 2013 Elsevier B.V. All rights reserved.

Plasma deposition of polymer composite films incorporating nanocellulose whiskers

Science.gov (United States)

Samyn, P.; Airoudj, A.; Laborie, M.-P.; Mathew, A. P.; Roucoules, V.

2011-11-01

In a trend for sustainable engineering and functionalization of surfaces, we explore the possibilities of gas phase processes to deposit nanocomposite films. From an analysis of pulsed plasma polymerization of maleic anhydride in the presence of nanocellulose whiskers, it seems that thin nanocomposite films can be deposited with various patterns. By specifically modifying plasma parameters such as total power, duty cycle, and monomer gas pressure, the nanocellulose whiskers are either incorporated into a buckled polymer film or single nanocellulose whiskers are deposited on top of a polymeric film. The density of the latter can be controlled by modifying the exact positioning of the substrate in the reactor. The resulting morphologies are evaluated by optical microscopy, AFM, contact angle measurements and ellipsometry.

Low-temperature strain gauges based on silicon whiskers

Directory of Open Access Journals (Sweden)

Druzhinin A. A.

2008-08-01

Full Text Available To create low-temperature strain gauges based on p-type silicon whiskers tensoresistive characteristics of these crystals in 4,2—300 K temperature range were studied. On the basis of p-type Si whiskers with different resistivity the strain gauges for different materials operating at cryogenic temperatures with extremely high gauge factor at 4,2 K were developed, as well as strain gauges operating at liquid helium temperatures in high magnetic fields.

Innovation Incubator: Whisker Labs Technical Evaluation

Energy Technology Data Exchange (ETDEWEB)

Sparn, Bethany F. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Frank, Stephen M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Earle, Lieko [National Renewable Energy Lab. (NREL), Golden, CO (United States); Scheib, Jennifer G. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2017-08-01

The Wells Fargo Innovation Incubator (IN2) is a program to foster and accelerate startup companies with commercial building energy-efficiency and demand management technologies. The program is funded by the Wells Fargo Foundation and co-administered by the National Renewable Energy Laboratory (NREL). Whisker Labs, an Oakland, California-based company, was one of four awardees in the first IN2 cohort and was invited to participate in the program because of its novel electrical power sensing technology for circuit breakers. The stick-on Whisker meters install directly on the front face of the circuit breakers in an electrical panel using adhesive, eliminating the need to open the panel and install current transducers (CTs) on the circuit wiring.

DC Characterisation of C60 Whiskers and Nanowhiskers

DEFF Research Database (Denmark)

Larsson, Michael; Kjelstrup-Hansen, Jakob; Lucyszyn, Stepan

2007-01-01

C60 whiskers exhibit increasing conductivity with decreasing diameter. At diameters of 1 mm and below, a single-crystal structure predominates, and enhanced electrical characteristics are expected; however, no supporting data exists in the literature. Here, results of four-point probe measurements......, indicating strong potential for use in organic electronic applications of the future. Repeated current cycling in air is observed to promote sample degradation, possibly due to progressive oxidation of the carbon structure. A micromachined four-point probe is also used to try to establish non...... on C60 whiskers and nanowhiskers with diameters in the range 650 nm to 1.3 mm are reported for the first time. Samples are attached to pre-patterned planar and raised electrodes using FIB-deposited tungsten. A low resistivity of 3 Wcm is measured in air, on a C60 whisker having a diameter of 650 nm...

Surface modification of magnesium hydroxide sulfate hydrate whiskers using a silane coupling agent by dry process

International Nuclear Information System (INIS)

Zhu, Donghai; Nai, Xueying; Lan, Shengjie; Bian, Shaoju; Liu, Xin; Li, Wu

2016-01-01

Highlights: • Dry process was adopted to modify the surface of MHSH whiskers using silane. • Si−O−Mg bonds were formed directly by the reaction between Si−OC 2 H 5 and −OH of MHSH. • Dispersibility and compatibility of modified whiskers greatly improved in organic phase. • Thermal stability of whiskers was enhanced after modified. - Abstract: In order to improve the compatibility of magnesium hydroxide sulfate hydrate (MHSH) whiskers with polymers, the surface of MHSH whiskers was modified using vinyltriethoxysilane (VTES) by dry process. The possible mechanism of the surface modification and the interfacial interactions between MHSH whiskers and VTES, as well as the effect of surface modification, were studied. Scanning electronic microscopy (SEM), transmission electron microscopy (TEM) and X-ray powder diffraction (XRD) analyses showed that the agglomerations were effectively separated and a thin layer was formed on the surface of the whiskers after modification. Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses showed that the VTES molecules were bound to the surface of MHSH whiskers after modification. Chemical bonds (Si−O−Mg) were formed by the reaction between Si−OC 2 H 5 or Si−OH and the hydroxyl group of MHSH whiskers. The effect of surface modification was evaluated by sedimentation tests, contact angle measurements and thermogravimetric analysis (TGA). The results showed that the surface of MHSH whiskers was transformed from hydrophilic to hydrophobic, and the dispersibility and the compatibility of MHSH whiskers were significantly improved in the organic phase. Additionally, the thermal stability of the VTES-modified MHSH whiskers was improved significantly.

Effects of bias voltage on the corrosion resistance of titanium nitride thin films fabricated by dynamic plasma immersion ion implantation-deposition

International Nuclear Information System (INIS)

Tian Xiubo; Fu, Ricky K. Y.; Chu, Paul K.

2002-01-01

Dynamic plasma-based thin-film deposition incorporating ion mixing and plasma immersion is an effective technique to synthesize nitride-based hard films. We have fabricated TiN films using a filtered titanium vacuum arc in a nitrogen plasma environment. A pulsed high voltage is applied to the target for a short time when the metallic arc is fired to attain simultaneous plasma deposition and ion mixing. We investigate the dependence of the corrosion resistance and interfacial structure of the treated samples on the applied voltage. Our Auger results reveal an oxygen-rich surface film due to the non-ultra-high-vacuum conditions and high affinity of oxygen to titanium. The corrosion current is reduced by two orders of magnitude comparing the sample processed at 8 kV to the untreated sample, but the 23 kV sample unexpectedly shows worse results. The pitting potential diminishes substantially although the corrosion current is similar to that observed in the 8 kV sample. The polarization test data are consistent with our scanning electron microscopy observation, corroborating the difference in the pitting distribution and appearance. This anomalous behavior is believed to be due to the change in the chemical composition as a result of high-energy ion bombardment

Effects of local film properties on the nucleation and growth of tin whiskers and hillocks

Science.gov (United States)

Sarobol, Pylin

Whiskers and hillocks grow spontaneously on Pb-free Sn electrodeposited films as a response to thin film stresses. Stress relaxation occurs by atom deposition to specific grain boundaries in the plane of the film, with hillocks being formed when grain boundary migration accompanies growth out of the plane of the film. The implication for whisker formation in electronics is serious: whiskers can grow to be millimeters long, sometimes causing short circuiting between adjacent components and, thereby, posing serious electrical reliability risks. In order to develop more effective whisker mitigation strategies, a predictive physics-based model has been needed. A growth model is developed, based on grain boundary faceting, localized Coble creep, as well as grain boundary sliding for whiskers, and grain boundary sliding with shear induced grain boundary migration for hillocks. In this model of whisker formation, two mechanisms are important: accretion of atoms by Coble creep on grain boundary planes normal to the growth direction inducing a grain boundary shear and grain boundary sliding in the direction of whisker growth. The model accurately captures the importance of the geometry of "surface grains"---shallow grains on film surfaces whose depths are significantly less than their in-plane grain sizes. A critical factor in the analysis is the ratio of the grain boundary sliding coefficient to the in-plane film compressive stress. If the accretion-induced shear stresses are not coupled to grain boundary motion and sliding occurs, a whisker forms. If the shear stress is coupled to grain boundary migration, a hillock forms. Based on this model, long whiskers grow from shallow surface grains with easy grain boundary sliding in the direction of growth. Other observed growth morphologies will be discussed in light of our model. Additional insights into the preferred sites for whisker and hillock growth were developed based on elastic anisotropy, local film microstructure

Theoretical and experimental analysis of the toughening behavior of whisker reinforcement in ceramic matrix composites

International Nuclear Information System (INIS)

Becher, P.F.; Hsueh, C.H.; Angelini, P.; Tiegs, T.N.

1988-01-01

Analytical solutions are presented describing the experimentally verified toughening of whisker reinforced ceramics. Clear insights are provided into the interrelationships of whiskers, matrices, and interfaces in the case of strong interfaces with minimized whisker pullout

Effect of compacting pressure, powder degassing and thermobaric treatment on densification and properties of nanocrystalline titanium nitride

Directory of Open Access Journals (Sweden)

Andrei V. Kapylou

2009-09-01

Full Text Available The effects of compacting pressure, powder degassing and high pressure sintering temperature and time on the densification and properties of nanocrystalline titanium nitride have been investigated. For this reason, TiN powder with a mean particle size of 55 nm was pressed in the range of compacting pressure from 0.2 to 1.0 GPa and sintered under static pressure of 3.5 GPa in the temperature range of 900–1600°C for 45–120 s. Some of green bodies were degassed in vacuum before sintering. It was shown that samples compacted in the pressure range of 0.2–0.6 GPa have the highest density after the thermobaric treatment. The maximum density (about 97.3 %TD was obtained with degassed samples. Microhardness and microstructure investigations have shown that recrystallization of the TiN nanopowder begins at the sintering temperatures of 1100–1200°C and sintering time less than one minute. The maximum microhardness obtained was 23.2±1.0 GPa and themaximum Young modulus was 370 GPa.

Whiskers and fibers of hydroxyapatite; Whiskers e fibras de hidroxiapatita

Energy Technology Data Exchange (ETDEWEB)

Cardoso, G.B.C.; Motisuke, M.; Zavaglia, C.A.C., E-mail: guicardoso@fem.unicamp.b [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. de Engenharia Mecanica. Dept. de Engenharia de Materiais; Arruda, A.C.F. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. de Engenharia Mecanica. Dept. de Engenharia de Petroleo

2009-07-01

Hydroxyapatite is a bioactive ceramic, which acts in tissue engineering by attracting bone cells. Occasionally it can be used as a biocompatible reinforcement. The mechanical role of this biomaterial can be defined depending of some characteristics analyzed by scanning electron microscope and X ray power diffraction. It can be classified in whiskers and fibers; each one has their own properties, which were discussed in this work. For its use as reinforcement it is necessary matrix with specific characteristics. (author)

Development and Characterization of Titanium Compound N anostructures

Science.gov (United States)

Zhou, Zhou

The development and characterization of titanium compound nanostructures have been achieved, for potential applications in energy industry. Oil and gas, one of the traditional industry fields, observes accumulating demands on active implementations of nanotechnology, for the numerous advantages that nanomaterials can introduce to both product performances and field operations. By using chemical vapor deposition and liquid exfoliation, various titanium compound nanostructures have been synthesized through this project. Attractively, these two material fabrication methods have been recognized to be industrial friendly in terms of cost efficiency and productivity. The development of nanostructures, aiming at oil and gas field applications, presents novel solutions for existing issues, such as low durability of drilling tools, high friction in mechanical operations and ineffective heat dissipation. Titanium compound nanostructures, including titanium borides, nitrides and sulfides are therefore investigated for such applications as protective coating, lubrication and thermal management.

Formation of Ti-N graded bioceramic layer by DC hollow-cathode plasma nitriding

Institute of Scientific and Technical Information of China (English)

ZHENG Chuan-lin

2004-01-01

Ti-N graded ceramic layer was formed on titanium by using DC hollow-cathode plasma nitriding technique. The structure of Ti-N layer was analyzed using X-ray diffractometry(XRD) with Cu Kα radiation, and the microhardness( HV0.1) was measured from the surface to inner along the cross section of Ti-N layer. The results indicate that the Ti-N graded layer is composed of ε-Ti2 N, δ-TiN and α-Ti(N) phases. Mechanism discussion shows that hollow-cathode discharge can intensify gas ionization, increase current density and enhance the nitriding potential, which directly increases the thickness of the diffusion coatings compared with traditional nitriding methods.

Extraction and characterization of whiskers from Panicum grass cellulose fibers

International Nuclear Information System (INIS)

Martins, Douglas F.; Vieira, Julia G.; Pasquini, Daniel

2011-01-01

In this work are presented studies of the extraction of cellulose whiskers from Panicum grass fibers (Panicum maximum) by acid hydrolysis performed with H 2 SO 4 11.22 M. The fibers used in the hydrolysis process were previously purified and the efficiency of the purification process was evaluated by determining the lignin content by Klason method, before and after purification. The hydrolysis was performed at 40 degree C for 30 minutes. The whiskers were characterized by x-ray diffraction (XRD) and thermogravimetric analysis (TGA). It was verified a reduction in the crystallinity index and also a reduction of the degradation temperature of the whiskers in relation to the purified grass Panicum fibers. (author)

Peculiarities of magnetoresistance in InSb whiskers at cryogenic temperatures

Energy Technology Data Exchange (ETDEWEB)

Druzhinin, A., E-mail: druzh@polynet.lviv.ua [Lviv Polytechnic National University, Bandera Str., 12, 79013 Lviv (Ukraine); International Laboratory of High Magnetic Fields and Low Temperatures, Gajowicka 95, Wroclaw (Poland); Ostrovskii, I.; Khoverko, Yu. [Lviv Polytechnic National University, Bandera Str., 12, 79013 Lviv (Ukraine); International Laboratory of High Magnetic Fields and Low Temperatures, Gajowicka 95, Wroclaw (Poland); Liakh-Kaguy, N.; Khytruk, I. [Lviv Polytechnic National University, Bandera Str., 12, 79013 Lviv (Ukraine); Rogacki, K. [International Laboratory of High Magnetic Fields and Low Temperatures, Gajowicka 95, Wroclaw (Poland)

2015-12-15

Highlights: • Magnetoresistance in InSb whiskers with impurity concentration near MIT is studied. • SdH oscillations of transverse and longitudinal magnetoresistance are examined. • Mechanisms of electron scattering are determined • Main crystal parameters of InSb whiskers are determined. - Abstract: The study of the magnetoresistance in InSb whiskers with an impurity concentration in the vicinity to the metal-insulator phase transition, at low temperature range 4.2–77 K, and in fields, with induction up to 14 T, was conducted. The presence of Shubnikov-de Haas oscillations in both transverse and longitudinal magnetoresistance was observed. The following parameters of InSb whiskers were defined: period of oscillations 0.1 T{sup −1}, cyclotron effective mass of electrons m{sub c} ≈ 0.14m{sub o,} concentration of charge carriers 2.3 × 10{sup 17} cm{sup −3}, g-factor g{sup *} ≈ 30 and Dingle temperature T{sub D} = 14.5 K. To determine the nature of crystal defects, the electron scattering processes on the short-range potential, caused by interaction with polar and nonpolar optical phonons, piezoelectric and acoustic phonons, static strain centers and ionized impurities in n-InSb whiskers, with defect concentration 2.9 × 10{sup 17} cm{sup −3}, are considered. The temperature dependences of electron mobility in the range 4.2–500 K were calculated.

Low-temperature ({<=}200 Degree-Sign C) plasma enhanced atomic layer deposition of dense titanium nitride thin films

Energy Technology Data Exchange (ETDEWEB)

Samal, Nigamananda; Du Hui; Luberoff, Russell; Chetry, Krishna; Bubber, Randhir; Hayes, Alan; Devasahayam, Adrian [Veeco Instruments, 1 Terminal Drive, Plainview, New York 11803 (United States)

2013-01-15

Titanium nitride (TiN) has been widely used in the semiconductor industry for its diffusion barrier and seed layer properties. However, it has seen limited adoption in other industries in which low temperature (<200 Degree-Sign C) deposition is a requirement. Examples of applications which require low temperature deposition are seed layers for magnetic materials in the data storage (DS) industry and seed and diffusion barrier layers for through-silicon-vias (TSV) in the MEMS industry. This paper describes a low temperature TiN process with appropriate electrical, chemical, and structural properties based on plasma enhanced atomic layer deposition method that is suitable for the DS and MEMS industries. It uses tetrakis-(dimethylamino)-titanium as an organometallic precursor and hydrogen (H{sub 2}) as co-reactant. This process was developed in a Veeco NEXUS Trade-Mark-Sign chemical vapor deposition tool. The tool uses a substrate rf-biased configuration with a grounded gas shower head. In this paper, the complimentary and self-limiting character of this process is demonstrated. The effects of key processing parameters including temperature, pulse time, and plasma power are investigated in terms of growth rate, stress, crystal morphology, chemical, electrical, and optical properties. Stoichiometric thin films with growth rates of 0.4-0.5 A/cycle were achieved. Low electrical resistivity (<300 {mu}{Omega} cm), high mass density (>4 g/cm{sup 3}), low stress (<250 MPa), and >85% step coverage for aspect ratio of 10:1 were realized. Wet chemical etch data show robust chemical stability of the film. The properties of the film have been optimized to satisfy industrial viability as a Ruthenium (Ru) preseed liner in potential data storage and TSV applications.

Properties of ZnO whiskers under CO2-laser irradiation

International Nuclear Information System (INIS)

Shkumbatyuk, P. S.

2010-01-01

Needlelike ZnO single crystals (whiskers) 0.3-0.8 mm long and 1-10 μm in diameter with a resistivity from 3 x 10 2 to 1 Ω cm have been grown under cw CO 2 -laser irradiation. The whiskers exhibit weak electroluminescence caused by injection from contacts with participation of intrinsic defects, which affect the electric field distribution.

Estimation of sensing characteristics for refractory nitrides based gain assisted core-shell plasmonic nanoparticles

Science.gov (United States)

Shishodia, Manmohan Singh; Pathania, Pankaj

2018-04-01

Refractory transition metal nitrides such as zirconium nitride (ZrN), hafnium nitride (HfN) and titanium nitride (TiN) have emerged as viable alternatives to coinage metals based plasmonic materials, e.g., gold (Au) and silver (Ag). The present work assesses the suitability of gain assisted ZrN-, HfN- and TiN-based conventional core-shell nanoparticles (CCSNPs) and multilayered core-shell nanoparticles (MCSNPs) for refractive index sensing. We report that the optical gain incorporation in the dielectric layer leads to multifold enhancement of the scattering efficiency (Qsca), substantial reduction of the spectral full width at half maximum, and a higher figure of merit (FOM). In comparison with CCSNPs, the MCSNP system exhibits superior sensing characteristics such as higher FOM, ˜ 45% reduction in the critical optical gain, response shift towards the biological window, and higher degree of tunability. Inherent biocompatibility, growth compatibility, chemical stability and flexible spectral tuning of refractory nitrides augmented by superior sensing properties in the present work may pave the way for refractory nitrides based low cost sensing.

Fast feedback in active sensing: touch-induced changes to whisker-object interaction.

Directory of Open Access Journals (Sweden)

Dudi Deutsch

Full Text Available Whisking mediated touch is an active sense whereby whisker movements are modulated by sensory input and behavioral context. Here we studied the effects of touching an object on whisking in head-fixed rats. Simultaneous movements of whiskers C1, C2, and D1 were tracked bilaterally and their movements compared. During free-air whisking, whisker protractions were typically characterized by a single acceleration-deceleration event, whisking amplitude and velocity were correlated, and whisk duration correlated with neither amplitude nor velocity. Upon contact with an object, a second acceleration-deceleration event occurred in about 25% of whisk cycles, involving both contacting (C2 and non-contacting (C1, D1 whiskers ipsilateral to the object. In these cases, the rostral whisker (C2 remained in contact with the object throughout the double-peak phase, which effectively prolonged the duration of C2 contact. These "touch-induced pumps" (TIPs were detected, on average, 17.9 ms after contact. On a slower time scale, starting at the cycle following first touch, contralateral amplitude increased while ipsilateral amplitude decreased. Our results demonstrate that sensory-induced motor modulations occur at various timescales, and directly affect object palpation.

Effect of SiC whisker addition on the microstructures and mechanical properties of Ti(C, N)-based cermets

International Nuclear Information System (INIS)

Wu, Peng; Zheng, Yong; Zhao, Yongle; Yu, Haizhou

2011-01-01

Ti(C, N)-based cermets with addition of SiC whisker (SiC w ) were prepared by vacuum sintering. The microstructures of the prepared cermets were investigated by using X-ray diffractometry (XRD) and scanning electron microscopy (SEM). Mechanical properties such as transverse rupture strength (TRS), fracture toughness (K IC ) and hardness (HRA) were also measured. It was found that the grain size of the cermets was affected by the SiC whisker addition. The cermets with 1.0 wt.% SiC whisker addition exhibited the smallest grain size. The porosities of the cermets increased with increasing SiC whisker additions. The addition of the SiC whisker had no influence on the phase constituents of the cermets. Compared with the cermets with no whisker addition, the highest TRS and fracture toughness for cermets with 1.0 wt.% SiC whisker addition increased by about 24% and 29%, respectively. The strengthening mechanisms were attributed to finer grain size, homogeneous microstructure and moderate thickness of rim phase. The toughening mechanisms were characterized by crack deflection, whisker bridging and whisker pulling-out.

In-situ measurement of bending strength of TiC whiskers in the scanning electron microscope

Energy Technology Data Exchange (ETDEWEB)

Seino, Yutaka; Shin, Shoichiro; Nagai, Satoshi [National Research Lab. of Metrology, Tsukuba, Ibaraki (Japan)

1995-10-01

The three-point bending strength of TiC whiskers was measured in a scanning electron microscope. The whisker samples have {approximately} 50 {micro}m length and 2 {approximately} 4 {micro}m diameter and are commercially available as reinforcements. For composite materials. The distribution of the bending strengths of the whiskers showed a double peak around 5.2GPa and 30.4GPa, respectively. The difference in these values is attributed to differences in the cleavage strength of two crystal planes depending on whisker growth direction.

Transient Nonlinear Optical Properties of Thin Film Titanium Nitride

Science.gov (United States)

2017-03-23

13] • Chemical composition • Crystal structure and lattice parameters • Defect structure This tuneability will be useful in future engineering ...Nitride SarahKatie Thomas Follow this and additional works at: https://scholar.afit.edu/etd Part of the Materials Science and Engineering Commons This... Thesis is brought to you for free and open access by AFIT Scholar. It has been accepted for inclusion in Theses and Dissertations by an authorized

Titanium nitride as an electrocatalyst for V(II)/V(III) redox couples in all-vanadium redox flow batteries

International Nuclear Information System (INIS)

Yang, Chunmei; Wang, Haining; Lu, Shanfu; Wu, Chunxiao; Liu, Yiyang; Tan, Qinglong; Liang, Dawei; Xiang, Yan

2015-01-01

Titanium nitride nanoparticles (TiN NPs) are proposed as a novel catalyst towards the V(II)/V(III) redox pair for the negative electrode in vanadium redox flow batteries (VRFB). Electrochemical properties of TiN NPs were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results show that TiN NPs demonstrate better electrochemical activity and reversibility for the processes of V(II)/V(III) redox couples as compared with the graphite NPs. TiN NPs facilitate the charge transfer in the V(II)/V(III) redox reaction. Performance of a VRFB using a TiN NPs coated carbon paper as a negative electrode is much higher than that of a VRFB with a raw carbon paper electrode. The columbic efficiency (CE), the voltage efficiency (VE) and the energy efficiency (EE) of the VRFB single cell at charge-discharge current density of 30 mA/cm 2 are 91.74%, 89.11% and 81.74%, respectively. During a 50 charge-discharge cycles test, the CE values of VRFB with TiN NPs consistently remain higher than 90%.

Contributions of stress and oxidation on the formation of whiskers in Pb-free solders

Energy Technology Data Exchange (ETDEWEB)

Duncan, A. J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hoffman, E. N. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2016-01-01

Understanding the environmental factors influencing formation of tin whiskers on electrodeposited lead free, tin coatings over copper (or copper containing) substrates is the topic of this study . An interim report* summarized initial observations as to the role of stress and oxide formation on whisker growth. From the initial results, two main areas were chosen to be the focus of additional research: the demonstration of effects of elastic stress state in the nucleation of whiskers and the confirmation of the effect of oxygen content in the formation of whiskers. Different levels of elastic stress were induced with the incorporation of a custom designed fixture that loaded the sample in a four-point bending configuration and were maintained in an environmental chamber under conditions deemed favorable for whisker growth. The effects of oxygen content were studied by aging substrates in gas vials of varying absolute pressure and different oxygen partial pressure.

Structure and Properties of Chitin Whisker Reinforced Papers for Food Packaging Application

Directory of Open Access Journals (Sweden)

Zhihan Li

2015-04-01

Full Text Available In recent years, concerns about environmental waste caused by petroleum-derived chemicals as well as the consumer's demand for high quality food products, have prompted people to pay more attention to developing biodegradable food packaging materials using natural resources such as cellulose fibers and chitin derivatives. In this study, chitin whiskers have been successfully generated by hydrolyzing the α-chitin sample. Then the synthesized nano-sized chitin whiskers were used at ratios from 0.1% to 2% (wt% for improving strength properties of paper sheets by the dip-coating method. Transmission electron microscopy (TEM and field emission scanning electron microscopy (FE-SEM were used to investigate the morphology of chitin whiskers and cellulose fiber compounds. The results showed that coating with chitin whiskers brought about an increase in tear strength, burst strength, and wet and dry tensile strength, with a decrease in Zeta-potential value.

{sup 14}N depth profiles in Ti and Ti6Al4V nitrided by various methods, measured by nuclear reaction analysis

Energy Technology Data Exchange (ETDEWEB)

Vickridge, I.; Trompetter, B. [Institute of Geological and Nuclear Sciences Ltd., Lower Hutt (New Zealand); Brown, I. [Industrial Research Ltd, Lower Hutt (New Zealand)

1993-12-31

Titanium alloys have desirable mechanical properties for applications in many areas, but their surface properties, such as friction coefficient, hardness, and wear and corrosion resistance often need to be enhanced. This may be accomplished by forming a thin layer of titanium nitride on the surface, by such methods as thermal nitriding, Ion Beam Assisted Deposition (IBAD), sol-gel technology, or ion implantation. Ion Beam Analysis is assuming an increasing importance for characterising the composition of the outer few microns since it is the only technique that can rapidly yield quantitative concentration depth profiles of {sup 14}N with minimal disruption of the analysed region. 8 refs., 7 figs.

{sup 14}N depth profiles in Ti and Ti6Al4V nitrided by various methods, measured by nuclear reaction analysis

Energy Technology Data Exchange (ETDEWEB)

Vickridge, I; Trompetter, B [Institute of Geological and Nuclear Sciences Ltd., Lower Hutt (New Zealand); Brown, I [Industrial Research Ltd, Lower Hutt (New Zealand)

1994-12-31

Titanium alloys have desirable mechanical properties for applications in many areas, but their surface properties, such as friction coefficient, hardness, and wear and corrosion resistance often need to be enhanced. This may be accomplished by forming a thin layer of titanium nitride on the surface, by such methods as thermal nitriding, Ion Beam Assisted Deposition (IBAD), sol-gel technology, or ion implantation. Ion Beam Analysis is assuming an increasing importance for characterising the composition of the outer few microns since it is the only technique that can rapidly yield quantitative concentration depth profiles of {sup 14}N with minimal disruption of the analysed region. 8 refs., 7 figs.

Synthesis and characterization of nano silicon and titanium nitride ...

Indian Academy of Sciences (India)

The characterization techniques indicated ... Scalable synthesis; microwave plasma; chemical synthesis; nanoparticles. 1. Introduction ... used but very few methods are available to produce silicon and titanium ... current (A). (m3/h). 1. Si. 2.1.

Characterization of microstructure of Si3N4 whisker reinforced glass ceramic

International Nuclear Information System (INIS)

Han, Byoung Sung; Choi, Shung Shaon

1993-01-01

Glass ceramics, especially fiber-reinforced composite ceramics, have attracted a great deal of attention in improving the reliability of ceramic components because of the improvement in various mechanical properties. Through hot-pressing and sintering, 225 cordierite was transformed with glass ceramic and mullite phase. Particularly glass glain size increased with the increasing of the sintering temperature and the heat treatment enhance the toughness and hardness of materials. Like the increased sintering temperature, the roughness increased with increasing whisker vol.%. In case of whisker-rinforced glass ceramic, the fracture surface of samples has been associated with a whisker orientation of samples. (Author)

Hydrothermal Formation Of Hemi-hydrate Calcium Sulfate Whiskers In The Presence Of Additives

International Nuclear Information System (INIS)

Luo, K. B.; Li, C. M.; Li, H. P.; Ning, P.; Xiang, L.

2010-01-01

The influence of addictives on the hydrothermal formation of hemi-hydrate calcium sulfate (CaSO 4 ·0.5H 2 O) whiskers were discussed in this paper, using CaCl 2 and Na 2 SO 4 as the reactants. The presence of NaCl, CaCl 2 or Na 2 SO 4 increased the concentrations of Ca 2+ and SO 4 2- , leading to the formation of CaSO 4 ·0.5H 2 O whiskers with aspect ratio lower than 50. The one dimensional growth of CaSO 4 ·0.5H 2 O whiskers was enhanced in water with no additives owing to the low super-saturation, leading to the formation of uniform whiskers with a length of 200-2000 μm and an aspect ratio higher than 100.

Isolation of whiskers from natural sources and their dispersed in a non-aqueous medium

Directory of Open Access Journals (Sweden)

Mauro Vestena

Full Text Available Abstract Whiskers have been used as a nanomaterial dispersed in polymer matrices to modify the microscopic and macroscopic properties of the polymer. These nanomaterials can be isolated from cellulose, one of the most abundant natural renewable sources of biodegradable polymer. In this study, whiskers were isolated from sugarcane bagasse and corn cob straw fibers. Initially, the cellulose fiber was treated through an alkaline/oxidative process followed by acid hydrolysis. Dimethylformamide and dimethyl sulfoxide were used to replace the aqueous medium for the dispersion of the whiskers. For the solvent exchange, dimethylformamide or dimethyl sulfoxide was added to the aqueous dispersion and the water was then removed by fractional distillation. FTIR, TGA, XRD, TEM, Zeta and DLS techniques were used to evaluate the efficiency of the isolation process as well as the morphology and dimensions of the whiskers. The dimensions of the whiskers are comparable with values reported in the literature, maintaining the uniformity and homogeneity in both aqueous and non-aqueous solvents.

Isolation of whiskers from natural sources and their dispersed in a non-aqueous medium

Energy Technology Data Exchange (ETDEWEB)

Vestena, Mauro; Gross, Idejan Padilha; Pires, Alfredo Tiburcio Nunes; Muller, Carmen Maria Olivera, E-mail: mauro@utfpr.edu.br [Universidade Federal Santa Catarina (UFSC), Florianopolis, SC (Brazil)

2016-10-15

Whiskers have been used as a nano material dispersed in polymer matrices to modify the microscopic and macroscopic properties of the polymer. These nanomaterials can be isolated from cellulose, one of the most abundant natural renewable sources of biodegradable polymer. In this study, whiskers were isolated from sugarcane bagasse and corn cob straw fibers. Initially, the cellulose fiber was treated through an alkaline/oxidative process followed by acid hydrolysis. Dimethylformamide and dimethyl sulfoxide were used to replace the aqueous medium for the dispersion of the whiskers. For the solvent exchange, dimethylformamide or dimethyl sulfoxide was added to the aqueous dispersion and the water was then removed by fractional distillation. FTIR, TGA, XRD, TEM, Zeta and DLS techniques were used to evaluate the efficiency of the isolation process as well as the morphology and dimensions of the whiskers. The dimensions of the whiskers are comparable with values reported in the literature, maintaining the uniformity and homogeneity in both aqueous and non-aqueous solvents. (author)

Effect of substrate temperature on the microstructural properties of titanium nitride nanowires grown by pulsed laser deposition

International Nuclear Information System (INIS)

Gbordzoe, S.; Kotoka, R.; Craven, Eric; Kumar, D.; Wu, F.; Narayan, J.

2014-01-01

The current work reports on the growth and microstructural characterization of titanium nitride (TiN) nanowires on single crystal silicon substrates using a pulsed laser deposition method. The physical and microstructural properties of the nanowires were characterized using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The corrosion properties of the TiN nanowires compared to TiN thin film were evaluated using Direct Current potentiodynamic and electrochemical impedance spectroscopy. The nanowires corroded faster than the TiN thin film, because the nanowires have a larger surface area which makes them more reactive in a corrosive environment. It was observed from the FESEM image analyses that as the substrate temperature increases from 600 °C to 800 °C, there was an increase in both diameter (25 nm–50 nm) and length (150 nm–250 nm) of the nanowire growth. There was also an increase in spatial density with an increase of substrate temperature. The TEM results showed that the TiN nanowires grow epitaxially with the silicon substrate via domain matching epitaxy paradigm, despite a large misfit

Contributions of Stress and Oxidation on the Formation of Whiskers in Pb-free Solders

Science.gov (United States)

2016-01-29

nucleation of whiskers and the confirmation of the effect of oxygen content in the formation of whiskers. Different levels of elastic stress were...substrate P Load RH Relative humidity max Stress at the top surface of the film SE Secondary Electrons SEM Scanning Electron Microscopy SRNL...demonstration of effects of stress state in the nucleation of whiskers and the confirmation of the effect of oxygen content in the formation of

Surface improvement and biocompatibility of TiAl{sub 24}Nb{sub 10} intermetallic alloy using rf plasma nitriding

Energy Technology Data Exchange (ETDEWEB)

Abd El-Rahman, A.M. [Physics Department, Faculty of Science, Sohag University (Egypt)], E-mail: ahmedphys96@hotmail.com; Maitz, M.F. [Institut fuer Ionenstrahlphysik und Materialforschung, Forschungszentrum Dresden Rossendorf (Germany); Kassem, M.A. [Department of Materials and Metals Engineering, Faculty of Petroleum and Mining Engineering, Suez Canal University (Egypt); El-Hossary, F.M. [Physics Department, Faculty of Science, Sohag University (Egypt); Prokert, F.; Reuther, H.; Pham, M.T.; Richter, E. [Institut fuer Ionenstrahlphysik und Materialforschung, Forschungszentrum Dresden Rossendorf (Germany)

2007-09-30

The present work describes the surface improvement and biocompatibility of TiAl{sub 24}Nb{sub 10} intermetallic alloy using rf plasma nitriding. The nitriding process was carried out at different plasma power from 400 W to 650 W where the other plasma conditions were fixed. Grazing incidence X-ray diffractometry (GIXRD), Auger electron spectroscopy (AES), tribometer and a nanohardness tester were employed to characterize the nitrided layer. Further potentiodynamic polarization method was used to describe the corrosion behavior of the un-nitrided and nitrided alloy. It has been found that the Vickers hardness (HV) and corrosion resistance values of the nitrided layers increase with increasing plasma power while the wear rates of the nitrided layers reduce by two orders of magnitude as compared to those of the un-nitrided layer. This improvement in surface properties of the intermetallic alloy is due to formation of a thin modified layer which is composed of titanium nitride in the alloy surface. Moreover, all modified layers were tested for their sustainability as a biocompatible material. Concerning the application area of biocompatibility, the present treated alloy show good surface properties especially for the nitrided alloy at low plasma power of 400 W.

Silicon carbide whiskers with superlattice structure: A precursor for a new type of nanoreactor

International Nuclear Information System (INIS)

Lutsenko, Vadym G.

2008-01-01

Silicon carbide whiskers exhibit growth predominantly in the direction. The high level of impurities, stacking faults and nanosized twins govern the formation of homojunctions and heterojunctions in crystals. The structure of the whiskers comprises a hybrid superlattice, i.e. contains elements of doped and composite superlattices. An individual SiC whisker can contain hundreds of quantum wells with anomalous chemical properties. This paper shows that it is possible to selectively etch quantum wells and to construct whiskers with quasi-regularly distributed slit-like nanopores (nanoreactors), which are bordered by polar planes {1 1 1}, {0 0 0 1} or a combination of them, and also to produce flat SiC nanocrystals bordered by polar planes

A new paradigm for the reversible blockage of whisker sensory transmission.

Science.gov (United States)

Gener, Thomas; Reig, Ramon; Sanchez-Vives, Maria V

2009-01-30

The objective of this study was to explore a paradigm that would allow a temporary deprivation of whisker information lasting for a few hours. An additional requirement was to be non-invasive in order to be usable in awake chronically implanted rats without inducing stress. With that aim, electrophysiological recordings from the barrel cortex of anesthetized rats were obtained. The pressure of an air-puff (5-10 ms) delivered to the whiskers was adjusted to evoke a consistent response of around 100 microV (extracellular) or approximately 5 mV (intracellular) in the contralateral cortex. Lidocaine was then locally applied in different forms (cream, local injection, aerosol, drops) and concentrations (2-10%) to the base of the whiskers. The stimulus-induced response was monitored once every 5s for several hours (3-6h) in order to characterize its course of action. Local injection of lidocaine induced the fastest and most complete blockage, but was ruled out for being invasive. Out of the remaining forms of application, a lidocaine drop (0.4 ml, 10%) to the base of the whiskers was found to induce a reliable blockage (to an average 9% the original response). The maximum effect was reached after 150-200 min, and the response was totally recovered approximately 300 min after lidocaine application. This characterization should be useful to induce an efficient, short term and reversible blockage of whisker sensory transmission in both anesthetized and awake preparations, while not causing stress in an awake animal.

Electronic and optical properties of titanium nitride bulk and surfaces from first principles calculations

Science.gov (United States)

Mehmood, Faisal; Pachter, Ruth; Murphy, Neil R.; Johnson, Walter E.

2015-11-01

Prediction of the frequency-dependent dielectric function of thin films poses computational challenges, and at the same time experimental characterization by spectroscopic ellipsometry remains difficult to interpret because of changes in stoichiometry and surface morphology, temperature, thickness of the film, or substrate. In this work, we report calculations for titanium nitride (TiN), a promising material for plasmonic applications because of less loss and other practical advantages compared to noble metals. We investigated structural, electronic, and optical properties of stoichiometric bulk TiN, as well as of the TiN(100), TiN(110), and TiN(111) outermost surfaces. Density functional theory (DFT) and many-body GW methods (Green's (G) function-based approximation with screened Coulomb interaction (W)) were used, ranging from G0W0, GW0 to partially self-consistent sc-GW0, as well as the GW-BSE (Bethe-Salpeter equation) and time-dependent DFT (TDDFT) methods for prediction of the optical properties. Structural parameters and the band structure for bulk TiN were shown to be consistent with previous work. Calculated dielectric functions, plasma frequencies, reflectivity, and the electron energy loss spectrum demonstrated consistency with experiment at the GW0-BSE level. Deviations from experimental data are expected due to varying experimental conditions. Comparison of our results to spectroscopic ellipsometry data for realistic nanostructures has shown that although TDDFT may provide a computationally feasible level of theory in evaluation of the dielectric function, application is subject to validation with GW-BSE calculations.

Non-destructive study of the ion-implantation-affected zone (the long-range effect) in titanium nitride

International Nuclear Information System (INIS)

Perry, A.J.; Treglio, J.R.; Schaffer, J.P.; Brunner, J.; Valvoda, V.; Rafaja, D.

1994-01-01

The depth to which metal ion implantation can change the structure of titanium nitride coatings is studied using two techniques - positron annihilation spectroscopy (PAS) and glancing-angle X-ray diffraction (GA-XRD) -which are normally applied to the study of bulk materials. The PAS results indicate that the depth to which vacancies are found greatly exceeds the depth at which the implanted material resides. In addition, the concentration of vacancies continues to increase with the dose of implanted ions. The GA-XRD data show that the implantation does not change the residual stress - it remains slightly tensile. Furthermore, there is an increase in the diffraction peak broadening, which is attributed to an increase in the local strain distribution resulting from the generation of a dislocation network at depths of up to several tenths of a micrometer below the implanted zone. The data support the view of a long-range effect, where metal ion implantation causes lattice defect generation within an implantation-affected zone (IAZ) to depths well beyond the implanted zone. The defective nature of the IAZ depends on the implanted dose and the acceleration voltage, as well as on the nature of the ions implanted. In the present work, there is no residual stress in the samples, so this cannot induce the IAZ. ((orig.))

Nanocomposite polymer electrolyte based on whisker or microfibrils polyoxyethylene nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Alloin, Fannie, E-mail: fannie.alloin@lepmi.grenoble-inp.f [LEPMI, Laboratoire d' Electrochimie et de Physicochimie des Materiaux et des Interfaces, Grenoble-INP-UJF-CNRS, UMR 5631, BP 75, 38041 Grenoble Cedex 9 (France); D' Aprea, Alessandra [Laboratoire de Rheologie, Grenoble-INP-UJF, UMR 5520, BP 53, 38041 Grenoble Cedex 9 (France); LEPMI, Laboratoire d' Electrochimie et de Physicochimie des Materiaux et des Interfaces, Grenoble-INP-UJF-CNRS, UMR 5631, BP 75, 38041 Grenoble Cedex 9 (France); Ecole Internationale du Papier, de la communication imprimee et des Biomateriaux, PAGORA- Grenoble-INP, BP 65, 38402 Saint Martin d' Heres Cedex (France); Kissi, Nadia El [Laboratoire de Rheologie, Grenoble-INP-UJF, UMR 5520, BP 53, 38041 Grenoble Cedex 9 (France); Dufresne, Alain [Ecole Internationale du Papier, de la communication imprimee et des Biomateriaux, PAGORA- Grenoble-INP, BP 65, 38402 Saint Martin d' Heres Cedex (France); Bossard, Frederic [Laboratoire de Rheologie, Grenoble-INP-UJF, UMR 5520, BP 53, 38041 Grenoble Cedex 9 (France)

2010-07-15

Nanocomposite polymer electrolytes composed of high molecular weight poly(oxyethylene) PEO as a matrix, LiTFSI as lithium salt and ramie, cotton and sisal whiskers with high aspect ratio and sisal microfibrils (MF), as reinforcing phase were prepared by casting-evaporation. The morphology of the composite electrolytes was investigated by scanning electron microscopy and their thermal behavior (characteristic temperatures, degradation temperature) were investigated by thermogravimetric analysis and differential scanning calorimetry. Nanocomposite electrolytes based on PEO reinforced by whiskers and MF sisal exhibited very high mechanical performance with a storage modulus of 160 MPa at high temperature. A weak decrease of the ionic conductivity was observed with the incorporation of 6 wt% of whiskers. The addition of microfibrils involved a larger decrease of the conductivity. This difference may be associated to the more restricted PEO mobility due to the addition of entangled nanofibers.

Selective ablation of a titanium nitride film on tungsten carbide substrate using ultrashort laser pulses

International Nuclear Information System (INIS)

Oliveira, Eduardo Spinelli

2017-01-01

Surface coatings are applied to many cutting tools in the metallurgical industry in order to improve cutting efficiency and extend its useful life. In this work, tests were performed to remove the coating of titanium aluminum nitride (TiAlN) on tungsten carbide (WC-Co) pellets, using an ultrashort laser pulses beam. After determination of the damage thresholds of the film and the substrate, were ablated on the surface of the coating lines using two ablation conditions, it was initially operated on the low fluence regime for the film, and later on the low fluence regime of the substrate, far below the threshold of the film, applying high overlapping pulses. A laser induced breakdown spectroscopy (LIBS) system was set up to monitor the materials present in the plasma generated by the laser, but the system did not present sufficient sensitivity to read the low intensity of the plasma generated in the process and was not used. After the analysis of the traces by electron microscopy, optical profilometer and X-ray fluorescence spectroscopy, it was not possible to determine a safe process to carry out the selective removal of the film in question, however, due to the data obtained and observations of the results in some traces, new possibilities were raised, opening the discussion for future work. (author)

A truncated conical beam model for analysis of the vibration of rat whiskers.

Science.gov (United States)

Yan, Wenyi; Kan, Qianhua; Kergrene, Kenan; Kang, Guozheng; Feng, Xi-Qiao; Rajan, Ramesh

2013-08-09

A truncated conical beam model is developed to study the vibration behaviour of a rat whisker. Translational and rotational springs are introduced to better represent the constraint conditions at the base of the whiskers in a living rat. Dimensional analysis shows that the natural frequency of a truncated conical beam with generic spring constraints at its ends is inversely proportional to the square root of the mass density. Under all the combinations of the classical free, pinned, sliding or fixed boundary conditions of a truncated conical beam, it is proved that the natural frequency can be expressed as f = α(rb/L(2))E/ρ and the frequency coefficient α only depends on the ratio of the radii at the two ends of the beam. The natural frequencies of a representative rat whisker are predicted for two typical situations: freely whisking in air and the tip touching an object. Our numerical results show that there exists a window where the natural frequencies of a rat whisker are very sensitive to the change of the rotational constraint at the base. This finding is also confirmed by the numerical results of 18 whiskers with their data available from literature. It can be concluded that the natural frequencies of a rat whisker can be adjusted within a wide range through manipulating the constraints of the follicle on the rat base by a behaving animal. Copyright © 2013 Elsevier Ltd. All rights reserved.

Hydrothermal formation and characterization of magnesium oxysulfate whiskers

International Nuclear Information System (INIS)

Xiang, L.; Liu, F.; Li, J.; Jin, Y.

2004-01-01

Magnesium oxysulfate (5Mg(OH) 2 ·MgSO 4 ·3H 2 O) whiskers with a diameter of 0.2-1.0 μm and a length of 20-50 μm were synthesized via the hydrothermal treatment of the slurry formed by mixing the MgSO 4 and NaOH solutions at room temperature. The composition, morphology, structure and thermal behavior of the hydrothermal products were examined with X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermo-gravimetric analysis (TGA) and chemical analysis. The experimental results indicated that the process parameters, such as the concentration of the reactant, the dispersion of the Mg(OH) 2 slurry and the temperature in hydrothermal treatment should be controlled carefully to synthesis 5Mg(OH) 2 ·MgSO 4 ·3H 2 O whiskers and to avoid the formation of the sectorial or granular impurities. 5Mg(OH) 2 ·MgSO 4 ·3H 2 O whiskers were decomposed gradually and converted finally to MgO particles after being heated in air at temperature up to 1050 deg. C. Granular products formed if the heating temperature was above 320 deg. C

Spontaneous growth of whiskers on RE-bearing intermetallic compounds of Sn-RE, In-RE, and Pb-RE

International Nuclear Information System (INIS)

Liu Meng; Xian Aiping

2009-01-01

A phenomenon of the whiskers growth on the bulk rare earth (RE)-intermetallic compounds of NdSn 3 , NdIn 3 , and LaPb 3 is reported. The whiskers formed spontaneously on all of the RE-intermetallic compounds after exposed to room ambience (21-28 deg. C/20-56% RH, relative humidity) for several days. Among the samples, the propensity of whisker growth for NdSn 3 is the strongest, on which the tin whiskers were flourishing and covered all of the surfaces after exposed to room ambience for 22 days; while LaPb 3 is the secondary and NdIn 3 is the last one. Observed by SEM, the whiskers were exhibited as different morphology, size, and number density. The XRD analysis confirms the existence of RE(OH) 3 after whiskers formed, also, the weight gain curve of the samples exposed to room ambience supports that a spontaneous chemical reaction of the RE-intermetallic compounds with water in room ambience takes place. In discussion, it is proposed that the fresh metal atoms released by the chemical reaction could be causative to result in nucleation and spontaneous growth of the whiskers, while the anisotropy of crystal structure could be a reason to understand the difference of the whisker growth behaviors between Sn and Pb.

Sensory prediction on a whiskered robot: A tactile analogy to "optic flow"

Directory of Open Access Journals (Sweden)

Christopher L Schroeder

2012-10-01

Full Text Available When an animal moves an array of sensors (e.g., the hand, the eye through the environment, spatial and temporal gradients of sensory data are related by the velocity of the moving sensory array. In vision, the relationship between spatial and temporal brightness gradients is quantified in the optical flow equation. In the present work, we suggest an analog to optical flow for the rodent vibrissal (whisker array, in which the perceptual intensity that flows over the array is bending moment. Changes in bending moment are directly related to radial object distance, defined as the distance between the base of a whisker and the point of contact with the object. Using both simulations and a 1x5 array (row of artificial whiskers, we demonstrate that local object curvature can be estimated based on differences in radial distance across the array. We then develop two algorithms, both based on tactile flow, to predict the future contact points that will be obtained as the whisker array translates along the object. The translation of the robotic whisker array represents the rat's head velocity. The first algorithm uses a calculation of the local object slope, while the second uses a calculation of the local object curvature. Both algorithms successfully predict future contact points for simple surfaces. The algorithm based on curvature was found to more accurately predict future contact points as surfaces became more irregular. We quantify the inter-related effects of whisker spacing and the object’s spatial frequencies, and examine the issues that arise in the presence of real-world noise, friction, and slip.

Whiskers aid anemotaxis in rats.

Science.gov (United States)

Yu, Yan S W; Graff, Matthew M; Bresee, Chris S; Man, Yan B; Hartmann, Mitra J Z

2016-08-01

Observation of terrestrial mammals suggests that they can follow the wind (anemotaxis), but the sensory cues underlying this ability have not been studied. We identify a significant contribution to anemotaxis mediated by whiskers (vibrissae), a modality previously studied only in the context of direct tactile contact. Five rats trained on a five-alternative forced-choice airflow localization task exhibited significant performance decrements after vibrissal removal. In contrast, vibrissal removal did not disrupt the performance of control animals trained to localize a light source. The performance decrement of individual rats was related to their airspeed threshold for successful localization: animals that found the task more challenging relied more on the vibrissae for localization cues. Following vibrissal removal, the rats deviated more from the straight-line path to the air source, choosing sources farther from the correct location. Our results indicate that rats can perform anemotaxis and that whiskers greatly facilitate this ability. Because air currents carry information about both odor content and location, these findings are discussed in terms of the adaptive significance of the interaction between sniffing and whisking in rodents.

Growth of cadmium oxide whiskers on cadmium sulphide single crystals with copper as growth activator

Energy Technology Data Exchange (ETDEWEB)

Koparanova, N.; Simov, S. (Bylgarska Akademiya na Naukite, Sofia. Inst. po Fizika na Tvyrdoto Tyalo); Genchev, D. (Bylgarska Akademiya na Naukite, Sofia. Inst. za Yadrena Izsledvaniya i Yadrena Energetika); Metchenov, G. (Research Inst. of Criminalistics and Criminology, Sofia (Bulgaria))

1985-02-01

Some results on the growth and morphology of cadmium oxide whiskers, obtained on cadmium sulphide single crystals with copper as a growth activator, are presented in this work. Cadmium oxide whiskers have been obtained on brace 112-bar0 brace faces of cadmium sulphide plates with a copper layer deposited in advance. The whiskers grew during the annealing of the plates in a weak stream of technically pure argon at temperatures 670 to 730 deg C for 15 min to 3.5 h. Details about the procedure have been given elsewhere. The composition and morphology of the whiskers have been studied by an X-ray microanalyser JEOL 35 DDS and a scanning electron microscope JEOL, JSM 35. The optical microscopic observations have shown that after annealing, a gray-black granular layer is formed on the cadmium sulphide single crystals and this layer can easily be separated from the crystal substrate. Under the granular layer the crystal is heavily damaged. The whiskers grow on the granular layer and they are coloured yellow-brown or red-brown. The maximum whisker length attains several hundreds of micrometres and in some cases up to 1 mm or more.

Growth of cadmium oxide whiskers on cadmium sulphide single crystals with copper as growth activator

International Nuclear Information System (INIS)

Koparanova, N.; Simov, S.

1985-01-01

Some results on the growth and morphology of cadmium oxide whiskers, obtained on cadmium sulphide single crystals with copper as a growth activator, are presented in this work. Cadmium oxide whiskers have been obtained on brace 112-bar0 brace faces of cadmium sulphide plates with a copper layer deposited in advance. The whiskers grew during the annealing of the plates in a weak stream of technically pure argon at temperatures 670 to 730 deg C for 15 min to 3.5 h. Details about the procedure have been given elsewhere. The composition and morphology of the whiskers have been studied by an X-ray microanalyser JEOL 35 DDS and a scanning electron microscope JEOL, JSM 35. The optical microscopic observations have shown that after annealing, a gray-black granular layer is formed on the cadmium sulphide single crystals and this layer can easily be separated from the crystal substrate. Under the granular layer the crystal is heavily damaged. The whiskers grow on the granular layer and they are coloured yellow-brown or red-brown. The maximum whisker length attains several hundreds of micrometres and in some cases up to 1 mm or more. (author)

The Effects of Oxidation Layer, Temperature, and Stress on Tin Whisker Growth: A Short Review

Science.gov (United States)

Mahim, Z.; Salleh, M. A. A.; Khor, C. Y.

2018-03-01

In order to reduce the Tin (Sn) whisker growth phenomenon in solder alloys, the researcher all the world has studied the factor of this behaviour. However, this phenomenon still hunted the electronic devices and industries. The whiskers growth were able to cause the electrical short, which would lead to the catastrophic such as plane crush, the failure of heart pacemaker, and the lost satellite connection. This article focuses on the three factors that influence the whiskers growth in solder alloys which is stress, oxidation layer and temperature. This findings were allowed the researchers to develop various method on how to reduce the growth of the Sn whiskers.

Spontaneous growth of whiskers on RE-bearing intermetallic compounds of Sn-RE, In-RE, and Pb-RE

Energy Technology Data Exchange (ETDEWEB)

Liu Meng [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Science, 72 Wenhua Road, Shenyang 110016 (China); Xian Aiping, E-mail: ap.xian@imr.ac.c [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Science, 72 Wenhua Road, Shenyang 110016 (China)

2009-11-03

A phenomenon of the whiskers growth on the bulk rare earth (RE)-intermetallic compounds of NdSn{sub 3}, NdIn{sub 3}, and LaPb{sub 3} is reported. The whiskers formed spontaneously on all of the RE-intermetallic compounds after exposed to room ambience (21-28 deg. C/20-56% RH, relative humidity) for several days. Among the samples, the propensity of whisker growth for NdSn{sub 3} is the strongest, on which the tin whiskers were flourishing and covered all of the surfaces after exposed to room ambience for 22 days; while LaPb{sub 3} is the secondary and NdIn{sub 3} is the last one. Observed by SEM, the whiskers were exhibited as different morphology, size, and number density. The XRD analysis confirms the existence of RE(OH){sub 3} after whiskers formed, also, the weight gain curve of the samples exposed to room ambience supports that a spontaneous chemical reaction of the RE-intermetallic compounds with water in room ambience takes place. In discussion, it is proposed that the fresh metal atoms released by the chemical reaction could be causative to result in nucleation and spontaneous growth of the whiskers, while the anisotropy of crystal structure could be a reason to understand the difference of the whisker growth behaviors between Sn and Pb.

Impacts of dissolved organic matter on aqueous behavior of nano/micron-titanium nitride and their induced enzymatic/non-enzymatic antioxidant activities in Scenedesmus obliquus.

Science.gov (United States)

Zhang, Xin; Wang, Zhuang; Wang, Se; Fang, Hao; Zhang, Fan; Wang, De-Gao

2017-01-02

Freshwater dispersion stability and ecotoxicological effects of titanium nitride (TiN) with particle size of 20 nm, 50 nm, and 2-10 μm in the presence of dissolved organic matter (DOM) at various concentrations were studied. The TiN particles that had a more negative zeta potential and smaller hydrodynamic size showed more stable dispersion in an aqueous medium when DOM was present than when DOM was absent. Biochemical assays indicated that relative to the control, the TiN particles in the presence of DOM alleviated to some extent the antioxidative stress enzyme activity in Scenedesmus obliquus. In addition, it was found that the TiN with a primary size of 50 nm at a high concentration presented a significant impact on non-enzymatic antioxidant defense in algal cells.

Matrix-reinforcement reactivity in P/M titanium matrix composites

International Nuclear Information System (INIS)

Amigo, V.; Romero, F.; Salvador, M. D.; Busquets, D.

2007-01-01

The high reactivity of titanium and the facility of the same one to form intermetallics makes difficult obtaining composites with this material and brings the need in any case of covering the principal fibres used as reinforcement. To obtain composites of titanium reinforced with ceramic particles ins proposed in this paper, for this reason it turns out to be fundamental to evaluate the reactivity between the matrix and reinforcement. Both titanium nitride and carbide (TiN and TiC) are investigated as materials of low reactivity whereas titanium silicide (TiSi 2 ) is also studied as materials of major reactivity, already stated by the scientific community. This reactivity will be analysed by means of scanning electron microscopy (SEM) there being obtained distribution maps of the elements that allow to establish the possible influence of the sintering temperature and time. Hereby the matrix-reinforcement interactions are optimized to obtain suitable mechanical properties. (Author) 39 refs

Cultured embryonic non-innervated mouse muzzle is capable of generating a whisker pattern.

Science.gov (United States)

Andrés, F L; Van Der Loos, H

1983-01-01

The whisker pattern on the muzzle of the mouse is mapped in the contralateral parietal neocortex, each whisker follicle projecting to its own multineuronal unit ('barrel'). To determine the role, if any, of the peripheral innervation in the establishment of the vibrissal array, we cultured non-innervated prospective whiskerpads from 9- and 10-day-old embryos, mostly on chorioallantoic membrane. The results show that skin, alone, is capable of generating the whisker pattern, thus adducing a strong argument for the hypothesis that the central brain maps have their origin in the periphery. Copyright © 1983. Published by Elsevier Ltd.

Influence of aluminium nitride as a foaming agent on the preparation of foam glass-ceramics from high-titanium blast furnace slag

Science.gov (United States)

Shi, Huan; Feng, Ke-qin; Wang, Hai-bo; Chen, Chang-hong; Zhou, Hong-ling

2016-05-01

To effectively reuse high-titanium blast furnace slag (TS), foam glass-ceramics were successfully prepared by powder sintering at 1000°C. TS and waste glass were used as the main raw materials, aluminium nitride (AlN) as the foaming agent, and borax as the fluxing agent. The influence of the amount of AlN added (1wt%-5wt%) on the crystalline phases, microstructure, and properties of the produced foam glass-ceramics was studied. The results showed that the main crystal phases were perovskite, diopside, and augite. With increasing AlN content, a transformation from diopside to augite occurred and the crystallinity of the pyroxene phases slightly decreased. Initially, the average pore size and porosity of the foam glass-ceramics increased and subsequently decreased; similarly, their bulk density and compressive strength decreased and subsequently increased. The optimal properties were obtained when the foam glass-ceramics were prepared by adding 4wt% AlN.

Surface modification of the titanium implant using TEA CO2 laser pulses in controllable gas atmospheres - Comparative study

International Nuclear Information System (INIS)

Ciganovic, J.; Stasic, J.; Gakovic, B.; Momcilovic, M.; Milovanovic, D.; Bokorov, M.; Trtica, M.

2012-01-01

Interaction of a TEA CO 2 laser, operating at 10.6 μm wavelength and pulse duration of 100 ns (FWHM), with a titanium implant in various gas atmospheres was studied. The Ti implant surface modification was typically studied at the moderate laser beam energy density/fluence of 28 J/cm 2 in the surrounding of air, N 2 , O 2 or He. The energy absorbed from the TEA CO 2 laser beam is partially converted to thermal energy, which generates a series of effects, such as melting, vaporization of the molten material, shock waves, etc. The following titanium implant surface changes and phenomena were observed, depending on the gas used: (i) creation of cone-like surface structures in the atmospheres of air, N 2 and O 2 , and dominant micro-holes/pores in He ambient; (ii) hydrodynamic features, most prominent in air; (iii) formation of titanium nitride and titanium oxide layers, and (iv) occurrence of plasma in front of the implant. It can be concluded from this study that the reported laser fluence and gas ambiences can effectively be applied for enhancing the titanium implant roughness and creation of titanium oxides and nitrides on the strictly localized surface area. The appearance of plasma in front of the implants indicates relatively high temperatures created above the surface. This offers a sterilizing effect, facilitating contaminant-free conditions.

In vitro formation of the Merkel cell-neurite complex in embryonic mouse whiskers using organotypic co-cultures.

Science.gov (United States)

Ishida, Kentaro; Saito, Tetsuichiro; Mitsui, Toshiyuki

2018-06-01

A Merkel cell-neurite complex is a touch receptor composed of specialized epithelial cells named Merkel cells and peripheral sensory nerves in the skin. Merkel cells are found in touch-sensitive skin components including whisker follicles. The nerve fibers that innervate Merkel cells of a whisker follicle extend from the maxillary branch of the trigeminal ganglion. Whiskers as a sensory organ attribute to the complicated architecture of the Merkel cell-neurite complex, and therefore it is intriguing how the structure is formed. However, observing the dynamic process of the formation of a Merkel cell-neurite complex in whiskers during embryonic development is still difficult. In this study, we tried to develop an organotypic co-culture method of a whisker pad and a trigeminal ganglion explant to form the Merkel cell-neurite complex in vitro. We initially developed two distinct culture methods of a single whisker row and a trigeminal ganglion explant, and then combined them. By dissecting and cultivating a single row from a whisker pad, the morphogenesis of whisker follicles could be observed under a microscope. After the co-cultivation of the whisker row with a trigeminal ganglion explant, a Merkel cell-neurite complex composed of Merkel cells, which were positive for both cytokeratin 8 and SOX2, Neurofilament-H-positive trigeminal nerve fibers and Schwann cells expressing Nestin, SOX2 and SOX10 was observed via immunohistochemical analyses. These results suggest that the process for the formation of a Merkel cell-neurite complex can be observed under a microscope using our organotypic co-culture method. © 2018 Japanese Society of Developmental Biologists.

Effects of surface treatment on the cavitation erosion of high-chrome steel, zirconium, titanium and their alloys

International Nuclear Information System (INIS)

Marinin, V.G.

1994-01-01

The erosion resistance of some structural materials used for equipment components of the first and second circuits of NPPs is studied under cavitation created by an ultrasonic vibrator. It appears that after various thermomechanical treatments (programmed loading, low-temperature rolling) and coating deposition (titanium, zirconium and titanium nitride), the erosion resistance of the materials under consideration increases and the plasticity value is not notably modified. The titanium coatings deposited onto the steel increase the corrosion-fatigue resistance in a sodium chloride environment, in several cases

Solid-state synthesis of Li_4Ti_5O_1_2 whiskers from TiO_2-B

International Nuclear Information System (INIS)

Yao, Wenjun; Zhuang, Wei; Ji, Xiaoyan; Chen, Jingjing; Lu, Xiaohua; Wang, Changsong

2016-01-01

Highlights: • The Li_4Ti_5O_1_2 whiskers were synthesized from TiO_2-B whiskers via a solid state reaction. • The TiO_2-B crystal structure for lithium diffusion is easier than anatase. • The separated diffusion and reaction process is crucial for the solid-state syntheses of Li_4Ti_5O_1_2 whiskers. - Abstract: In this work, Li_4Ti_5O_1_2 (LTO) was synthesized from the precursors of TiO_2-B and anatase whiskers, respectively. The synthesized LTO whiskers from TiO_2-B whiskers via a solid state reaction at 650 °C have a high degree of crystallinity with an average diameter of 300 nm. However, when anatase whiskers were used as the precursor, only particle morphology LTO was produced at 750 °C. The further analysis of the precursors, the intermediate products and the final products reveal that the crystal structure of the anatase hinders the diffusion of lithium, leading to a typical reaction–diffusion process. Under this condition, only particle morphology LTO can be produced. However, the crystal structure of the TiO_2-B is easy for lithium diffusion and the process is performed in two separated steps (i.e., diffusion and reaction), which makes it possible to decrease the solid-state reaction temperature down to 650 °C and then maintain the morphologies of whiskers.

Electronic and optical properties of titanium nitride bulk and surfaces from first principles calculations

International Nuclear Information System (INIS)

Mehmood, Faisal; Pachter, Ruth; Murphy, Neil R.; Johnson, Walter E.

2015-01-01

Prediction of the frequency-dependent dielectric function of thin films poses computational challenges, and at the same time experimental characterization by spectroscopic ellipsometry remains difficult to interpret because of changes in stoichiometry and surface morphology, temperature, thickness of the film, or substrate. In this work, we report calculations for titanium nitride (TiN), a promising material for plasmonic applications because of less loss and other practical advantages compared to noble metals. We investigated structural, electronic, and optical properties of stoichiometric bulk TiN, as well as of the TiN(100), TiN(110), and TiN(111) outermost surfaces. Density functional theory (DFT) and many-body GW methods (Green's (G) function-based approximation with screened Coulomb interaction (W)) were used, ranging from G 0 W 0 , GW 0 to partially self-consistent sc-GW 0 , as well as the GW-BSE (Bethe-Salpeter equation) and time-dependent DFT (TDDFT) methods for prediction of the optical properties. Structural parameters and the band structure for bulk TiN were shown to be consistent with previous work. Calculated dielectric functions, plasma frequencies, reflectivity, and the electron energy loss spectrum demonstrated consistency with experiment at the GW 0 -BSE level. Deviations from experimental data are expected due to varying experimental conditions. Comparison of our results to spectroscopic ellipsometry data for realistic nanostructures has shown that although TDDFT may provide a computationally feasible level of theory in evaluation of the dielectric function, application is subject to validation with GW-BSE calculations

Effect of carbon coating on spontaneous C12A7 whisker formation

Science.gov (United States)

Zaikovskii, Vladimir I.; Volodin, Alexander M.; Stoyanovskii, Vladimir O.; Cherepanova, Svetlana V.; Vedyagin, Aleksey A.

2018-06-01

A carbon nanoreactor concept was applied to study the stabilization effect of carbon shell on phase composition and morphology of dodecacalcium hepta-aluminate Ca12Al14O33. The starting C12A7 powder was obtained using aluminum and calcium hydroxides as precursors. Carbon shell was formed by a chemical vapor deposition of divinyl at 550 °C. After the calcination at 1400 °C, the product was characterized by X-ray diffraction analysis (XRD) and high resolution transmission electron microscopy (HRTEM). It was observed for a first time that spontaneous formation of calcium aluminate whiskers take place under the conditions described. Each whisker consists of a 'head' (globular particle of 0.5 microns in diameter) and a 'tail' (prolonged whisker of few microns in length and 0.1-0.2 microns in diameter). According to HRTEM, the 'head' is characterized with microcrystal lattice of Ca12Al14O33 compound. XRD data show the presence of CaAl2O4 phase traces. The 'head' and 'tail' of the whisker are covered with structured graphene layers of 10 nm and 3 nm, correspondingly.

Surface Roughness and Tool Wear on Cryogenic Treated CBN Insert on Titanium and Inconel 718 Alloy Steel

International Nuclear Information System (INIS)

Thamizhmanii, S; Mohideen, R; Zaidi, A M A; Hasan, S

2015-01-01

Machining of materials by super hard tools like cubic boron nitride (cbn) and poly cubic boron nitride (pcbn) is to reduce tool wear to obtain dimensional accuracy, smooth surface and more number of parts per cutting edge. wear of tools is inevitable due to rubbing action between work material and tool edge. however, the tool wear can be minimized by using super hard tools by enhancing the strength of the cutting inserts. one such process is cryogenic process. this process is used in all materials and cutting inserts which requires wear resistance. the cryogenic process is executed under subzero temperature -186° celsius for longer period of time in a closed chamber which contains liquid nitrogen. in this research, cbn inserts with cryogenically treated was used to turn difficult to cut metals like titanium, inconel 718 etc. the turning parameters used is different cutting speeds, feed rates and depth of cut. in this research, titanium and inconel 718 material were used. the results obtained are surface roughness, flank wear and crater wear. the surface roughness obtained on titanium was lower at high cutting speed compared with inconel 718. the flank wear was low while turning titanium than inconel 718. crater wear is less on inconel 718 than titanium alloy. all the two materials produced saw tooth chips. (paper)

Marangoni Convection during Free Electron Laser Nitriding of Titanium

Science.gov (United States)

Höche, Daniel; Müller, Sven; Rapin, Gerd; Shinn, Michelle; Remdt, Elvira; Gubisch, Maik; Schaaf, Peter

2009-08-01

Pure titanium was treated by free electron laser (FEL) radiation in a nitrogen atmosphere. As a result, nitrogen diffusion occurs and a TiN coating was synthesized. Local gradients of interfacial tension due to the local heating lead to a Marangoni convection, which determines the track properties. Because of the experimental inaccessibility of time-dependent occurrences, finite element calculations were performed, to determine the physical processes such as heat transfer, melt flow, and mass transport. In order to calculate the surface deformation of the gas-liquid interface, the level set approach was used. The equations were modified and coupled with heat-transfer and diffusion equations. The process was characterized by dimensionless numbers such as the Reynolds, Peclet, and capillary numbers, to obtain more information about the acting forces and the coating development. Moreover, the nitrogen distribution was calculated using the corresponding transport equation. The simulations were compared with cross-sectional micrographs of the treated titanium sheets and checked for their validity. Finally, the process presented is discussed and compared with similar laser treatments.

Increasing Wear Resistance of Titanium Alloys by Anode Plasma Electrolytic Saturation with Interstitial Elements

Science.gov (United States)

Belkin, P. N.; Kusmanov, S. A.; Dyakov, I. G.; Silkin, S. A.; Smirnov, A. A.

2017-05-01

In our previous studies, we have shown that anode plasma electrolytic saturation of titanium alloys with nitrogen and carbon can improve their tribological properties. Obtained structure containing oxide layer and solid solution of diffused element in titanium promotes the enhancement of running-in ability and the decrease in the wear rate in some special cases. In this paper, further investigations are reported regarding the tribological properties of alpha- and beta-titanium alloys in wear test against hardened steel (50 HRC) disk using pin-on-disk geometry and balls of Al2O3 (6.25 mm in diameter) or bearing steel (9.6 mm in diameter) with ball-on-plate one and normal load from 5 to 209 N. Reproducible results were obtained under testing samples treated by means of the plasma electrolytic nitriding (PEN) with the mechanical removal of the oxide layer. Friction coefficient of nitrided samples is 0.5-0.9 which is somewhat higher than that for untreated one (0.48-0.75) during dry sliding against Al2O3 ball. An increase in the sliding speed results in the polishing of nitrided samples and reduction of their wear rate by 60 times. This result is obtained for 5 min at 850 °C using PEN in electrolyte containing 5 wt.% ammonia and 10 wt.% ammonium chloride followed by quenching in solution. Optical microscope was employed to assist in the evaluation of the wear behavior. Sizes of wear tracks were measured by profilometer TR200.

Titanium nitride room-temperature ferromagnetic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Morozov, Iu.G., E-mail: morozov@ism.ac.ru [Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, 8 Academician Osipyan Street, Chernogolovka, Moscow Region, 142432 (Russian Federation); Belousova, O.V. [Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, 8 Academician Osipyan Street, Chernogolovka, Moscow Region, 142432 (Russian Federation); Belyakov, O.A. [Ogarev Mordovia State University, Saransk, 68 Bol' shevistskaya Street, 430005 (Russian Federation); Parkin, I.P., E-mail: i.p.parkin@ucl.ac.uk [Department of Chemistry, Materials Chemistry Research Centre, University College London, 20 Gordon Street, London, WC1H 0AJ (United Kingdom); Sathasivam, S. [Department of Chemistry, Materials Chemistry Research Centre, University College London, 20 Gordon Street, London, WC1H 0AJ (United Kingdom); Kuznetcov, M.V., E-mail: maxim1968@mail.ru [All-Russian Research Institute on Problems of Civil Defense and Emergencies of Emergency Control Ministry of Russia (EMERCOM), 7 Davidkovskaya Street, Moscow, 121352 (Russian Federation)

2016-08-05

Cubic and near-spherical TiN nanoparticles ranging in average size from 20 to 125 nm were prepared by levitation-jet aerosol synthesis through condensation of titanium vapor in an inert gas flow with gaseous nitrogen injection. The nanoparticles were characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD), BET measurements, UV–Vis, FT-IR, Raman spectroscopy, XPS, and vibrating-sample magnetometry. Room-temperature ferromagnetism with maximum magnetization up to 2.5 emu/g was recorded for the nanoparticles. The results indicate that the observed ferromagnetic ordering was related to the defect Ti–N structures on the surface of nanoparticles. This suggestion is in good correlation with the measured spectroscopical data. - Highlights: • Levitation-jet aerosol synthesis of TiN nanoparticles (NPs). • SEM, XRD, BET, UV–vis, FT-IR, Raman, XPS and magnetic characterization of the NPs. • Correlation between optical and XPS measurements data and maximum magnetization of the NPs.

Growth, characterization, and physical properties of Bi-Sr-Ca-Cu-O superconducting whiskers

International Nuclear Information System (INIS)

Kraak, W.; Thiele, P.

1996-01-01

Single crystal whiskers of the Bi-based high-T c superconductors have been grown directly from the stoichiometric melt. Conditions for the preferable growth of the (2212) phase and annealing conditions for the conversion from the (2212) phase to the (2223) and (2234) Bi-based superconducting phases are achieved. The orientation and chemical composition of the crystals were characterized by X-ray diffractometry and energy dispersive X-ray analysis. Characteristic structural properties of the whiskers (incommensurable modulation in b-direction, peculiarities of dislocation networks) have been revealed by transmission electron microscopy and electron diffraction. Some special features of the broad superconducting transition in multiphase whiskers have been examined by spatially resolved measurements using low-temperature scanning electron microscopy. (orig.)

Sustainable carbothermal reduction and nitridation of Malaysian ilmenite by polyethylene terephthalate and coal

Science.gov (United States)

Ahmadi, Eltefat; Hamid, Sheikh Abdul Rezan Sheikh Abdul; Hussin, Hashim; Baharun, Norlia; Ariffin, Kamar Shah; Ramakrishnan, Sivakumar; Fauzi, M. N. Ahmad; Ismail, Hanafi

2017-07-01

In this paper, the carbothermal reduction and nitridation (CTRN) of Malaysian ilmenite has been studied as a part of crucial steps involved in reduction and subsequent chlorination processes for synthesizing titanium tetrachloride (TiCl4) from nitrided Malaysian ilmenite concentrates. In CTRN, waste plastics such as polyethylene terephthalate (PET) could be utilized as an alternative source of carbon reductant. In this study, titanium oxycarbonitride (TiOxCyNz) separated from iron (Fe) phase was synthesized by non-isothermal CTRN of Malaysian ilmenite under H2-N2 atmosphere by utilizing a mixture of Sarawak Mukah-Balingan coal and PET as reducing agents in a horizontal tube furnace. Experiments have been carried out in the temperature range of 1150-1250°C for 3 hours with various ratios of PET to coal (25 wt.% PET, 50 wt.% PET, and 75 wt.% PET). X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) methods of analysis were conducted to assess the microstructures and chemical compositions of the unreduced and reduced samples. The results indicated that utilizing PET had a significant effect on iron separation from titanium oxycarbonitride (TiO0.02C0.13N0.85) at 1250°C with a mixture of 75 wt.% PET. Furthermore, XRD and SEM studies demonstrated that with increasing PET weight ratio in the mixtures, the rate of conversion increased and a low-carbon TiOxCyNz with minimal intermediate titanium sub-oxides was synthesized. The method of applying PET as potential reductant for CTRN of ilmenite has beneficial side effects in sustainable recycling of waste PET.

An Empirical Model for Estimating the Probability of Electrical Short Circuits from Tin Whiskers. Part 2

Science.gov (United States)

Courey, Karim; Wright, Clara; Asfour, Shihab; Onar, Arzu; Bayliss, Jon; Ludwig, Larry

2009-01-01

In this experiment, an empirical model to quantify the probability of occurrence of an electrical short circuit from tin whiskers as a function of voltage was developed. This empirical model can be used to improve existing risk simulation models. FIB and TEM images of a tin whisker confirm the rare polycrystalline structure on one of the three whiskers studied. FIB cross-section of the card guides verified that the tin finish was bright tin.

Visible light induced electron transfer process over nitrogen doped TiO2 nanocrystals prepared by oxidation of titanium nitride

International Nuclear Information System (INIS)

Wu Zhongbiao; Dong Fan; Zhao Weirong; Guo Sen

2008-01-01

Nitrogen doped TiO 2 nanocrystals with anatase and rutile mixed phases were prepared by incomplete oxidation of titanium nitride at different temperatures. The as-prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), core level X-ray photoelectron spectroscopy (CL XPS), valence band X-ray photoelectron spectroscopy (VB XPS), UV-vis diffuse reflectance spectra (UV-vis DRS), and visible light excited photoluminescence (PL). The photocatalytic activity was evaluated for photocatalytic degradation of toluene in gas phase under visible light irradiation. The visible light absorption and photoactivities of these nitrogen doped TiO 2 nanocrystals can be clearly attributed to the change of the additional electronic (N - ) states above the valence band of TiO 2 modified by N dopant as revealed by the VB XPS and visible light induced PL. A band gap structure model was established to explain the electron transfer process over nitrogen doped TiO 2 nanocrystals under visible light irradiation, which was consistent with the previous theoretical and experimental results. This model can also be applied to understand visible light induced photocatalysis over other nonmetal doped TiO 2

Grinding Characteristics Of Directionally Aligned SiC Whisker Wheel-Comparison With Al2O3 Fiber Wheel

Institute of Scientific and Technical Information of China (English)

魏源迁; 山口胜美; 菊泽贤二; 洞口严; 中根正喜

2003-01-01

A unique SiC whisker wheel was invented,in which the whiskers were aligned normally to the grinding wheel surface.In this paper,grindabilities of the SiC whisker wheel are investigated and compared with those of other wheels of SiC grains,Al2O3 grains,as well as Al2O3 long and short fibres which were also aligned normally to the grinding wheel surface,respectively.The main research contents concern grinding characteristics of a directionally aligned SiC whisker wheel such as material-removal volume,wheel-wear rates,integrity of the ground surfaces,grinding ratios and grinding efficiency.Furthermore,grinding wheels of whiskers and fibres have a common disadvantage:they tend to load easily.The authors have proposed a simple method of loading-free grinding to overcome this propensity and investigate some related grinding characteristics under loading-free grinding conditions.

Stability to irradiation of SiGe whisker crystals used for sensors of physical values

Directory of Open Access Journals (Sweden)

Druzhinin A. A.

2011-04-01

Full Text Available An influence of g-irradiation (Co60 with doze up to 1—1018 сm–2 and magnetic field with induction up to 14 T on conduction of 1–xGex (х = 0,03 whisker crystals with resistivity of 0,08—0,025 Оhm·сm in temperature range 4,2—300 K have been studied. It is shown that whisker crystals resistance faintly varies under irradiation with doze 2·1017 сm–2, while their magnetoresistance substantially changes. The strain sensors stable to irradiation action operating in high magnetic fields on the base of the whiskers have been designed.

Neonatal Whisker Trimming Impairs Fear/Anxiety-Related Emotional Systems of the Amygdala and Social Behaviors in Adult Mice.

Directory of Open Access Journals (Sweden)

Hitomi Soumiya

Full Text Available Abnormalities in tactile perception, such as sensory defensiveness, are common features in autism spectrum disorder (ASD. While not a diagnostic criterion for ASD, deficits in tactile perception contribute to the observed lack of social communication skills. However, the influence of tactile perception deficits on the development of social behaviors remains uncertain, as do the effects on neuronal circuits related to the emotional regulation of social interactions. In neonatal rodents, whiskers are the most important tactile apparatus, so bilateral whisker trimming is used as a model of early tactile deprivation. To address the influence of tactile deprivation on adult behavior, we performed bilateral whisker trimming in mice for 10 days after birth (BWT10 mice and examined social behaviors, tactile discrimination, and c-Fos expression, a marker of neural activation, in adults after full whisker regrowth. Adult BWT10 mice exhibited significantly shorter crossable distances in the gap-crossing test than age-matched controls, indicating persistent deficits in whisker-dependent tactile perception. In contrast to controls, BWT10 mice exhibited no preference for the social compartment containing a conspecific in the three-chamber test. Furthermore, the development of amygdala circuitry was severely affected in BWT10 mice. Based on the c-Fos expression pattern, hyperactivity was found in BWT10 amygdala circuits for processing fear/anxiety-related responses to height stress but not in circuits for processing reward stimuli during whisker-dependent cued learning. These results demonstrate that neonatal whisker trimming and concomitant whisker-dependent tactile discrimination impairment severely disturbs the development of amygdala-dependent emotional regulation.

Method of activating an article of passive ferrous or non-ferrous metal prior to carburising, nitriding and /or nitrocarburising

DEFF Research Database (Denmark)

2011-01-01

Source: US2012111456A A method of activating an article of passive ferrous or non-ferrous metal by heating at least one compound containing nitrogen and carbon, wherein the article is treated with gaseous species derived from the compound. The activated article can be subsequently carburised......, nitrided or nitrocarburised in shorter time at lower temperature and resulting superior mechanical properties compared with non-activated articles and even articles of stainless steel, nickel alloy, cobalt alloy or titanium based material can be carburised, nitrided or nitrocarburised....

Surface modification of the titanium implant using TEA CO{sub 2} laser pulses in controllable gas atmospheres - Comparative study

Energy Technology Data Exchange (ETDEWEB)

Ciganovic, J.; Stasic, J.; Gakovic, B.; Momcilovic, M.; Milovanovic, D. [VINCA Institute of Nuclear Sciences, University of Belgrade, P.O. BOX 522, 11001 Belgrade (Serbia); Bokorov, M. [Faculty of Sciences, Department of Biology and Ecology, University of Novi Sad, Trg Dositeja Obradovica 3, 21000 Novi Sad (Serbia); Trtica, M., E-mail: etrtica@vinca.rs [VINCA Institute of Nuclear Sciences, University of Belgrade, P.O. BOX 522, 11001 Belgrade (Serbia)

2012-01-15

Interaction of a TEA CO{sub 2} laser, operating at 10.6 {mu}m wavelength and pulse duration of 100 ns (FWHM), with a titanium implant in various gas atmospheres was studied. The Ti implant surface modification was typically studied at the moderate laser beam energy density/fluence of 28 J/cm{sup 2} in the surrounding of air, N{sub 2}, O{sub 2} or He. The energy absorbed from the TEA CO{sub 2} laser beam is partially converted to thermal energy, which generates a series of effects, such as melting, vaporization of the molten material, shock waves, etc. The following titanium implant surface changes and phenomena were observed, depending on the gas used: (i) creation of cone-like surface structures in the atmospheres of air, N{sub 2} and O{sub 2}, and dominant micro-holes/pores in He ambient; (ii) hydrodynamic features, most prominent in air; (iii) formation of titanium nitride and titanium oxide layers, and (iv) occurrence of plasma in front of the implant. It can be concluded from this study that the reported laser fluence and gas ambiences can effectively be applied for enhancing the titanium implant roughness and creation of titanium oxides and nitrides on the strictly localized surface area. The appearance of plasma in front of the implants indicates relatively high temperatures created above the surface. This offers a sterilizing effect, facilitating contaminant-free conditions.

Comprehensive perspective on the mechanism of preferred orientation in reactive-sputter-deposited nitrides

International Nuclear Information System (INIS)

Kajikawa, Yuya; Noda, Suguru; Komiyama, Hiroshi

2003-01-01

Texture control of sputter-deposited nitride films has provoked a great deal of interest due to its technological importance. Despite extensive research, however, the reported results are scattered and discussions about the origin of preferred orientation (PO) are sometimes conflicting, and therefore controversial. The aim of this study is to acquire a clear perspective in order to discuss the origin of PO of sputter-deposited nitrides. Among nitrides, we focus on titanium nitride (TiN), aluminum nitride (AlN), and tantalum nitride (TaN), which are three commonly used nitrides. First, we collected reported experimental results about the relation between operating conditions and PO, because PO is considered to be determined by film formation processes, such as surface diffusion or grain growth, which is affected by operating conditions. We also collected reported results about such PO-determining processes. Then, we categorized the PO-determining processes into an initial stage and a growth stage of film deposition, and further categorized each stage into a vapor-solid interface and a solid-solid interface. Then, we related each stage and interface to film morphology and to PO-determining processes. Finally, based on existing results, previous models, and proposed schema, we discuss the origin of PO. Based on previous experimental results on film morphology, PO of nitride films occurred in the growth stage at the vapor-solid interface, where the sticking process of the precursor and the surface diffusion process determine PO, rather than in the initial stage and in the growth stage at the solid-solid interface. TiN (002) PO, however, seems to be caused in the initial stage at the solid-solid interface

Optical detections from worn and unworn titanium compound surfaces

DEFF Research Database (Denmark)

Rasmussen, Inge Lise; Guibert, M.; Martin, J.-M.

2010-01-01

of a titanium nitride (TiN) layer we obtain an increase in the reflected light as a result of wear. The relative change of reflectance of light from the tribological TiAlN coated surface to the underlying layer of TiN is similar for non-worn surfaces and for surfaces exposed to an abrasive wear process...... of a residual thickness of realistic tribological coatings prior to complete wear....

Effect of ion nitridation process on hardness and the corrosion resistance of biomaterials

International Nuclear Information System (INIS)

Wirjoadi; Lely Susita; Bambang Siswanto; Sudjatmoko

2012-01-01

Ion nitriding process has been performed on metal biomaterials to improve their mechanical properties of materials, particularly to increase hardness and corrosion resistance. This metallic biomaterials used for artificial bone or a prosthetic graft and used as devices of orthopedic biomaterials are usually of 316L SS metal-type and Ti-6Al-4V alloy. The purpose of this study is to research the development and utilization of ion nitridation method in order to get iron and titanium nitride thin films on the metallic biomaterials for artificial bone that has wear resistance and corrosion resistance is better. Microhardness of the samples was measured using a microhardness tester, optimum hardness of SS 316L samples are about 582 VHN, this was obtained at the nitriding temperature of 500 °C, the nitriding time of 3 hours and the nitrogen gas pressure of 1.6 mbar, while optimum hardness of Ti-6Al-4V alloy is 764 VHN, this was obtained at the nitriding temperature of 500 °C, the nitriding time of 4 hours and the nitrogen gas pressure of 1.6 mbar. The hardness value of SS 316L sample and Ti-6Al-4V alloy increase to 143% and 153%, if compared with standard samples. The optimum corrosion resistance at temperature of 350 °C for SS 316L and Ti-6Al-4V are 260,12 and 110,49 μA/cm 2 or corrosion rate are 29,866 and 15,189 mpy, respectively. (author)

Beta 2-adrenergic receptors are colocalized and coregulated with whisker barrels in rat somatosensory cortex

International Nuclear Information System (INIS)

Vos, P.; Kaufmann, D.; Hand, P.J.; Wolfe, B.B.

1990-01-01

Autoradiography has been used to visualize independently the subtypes of beta-adrenergic receptors in rat somatosensory cortex. Beta 2-adrenergic receptors, but not beta 1-adrenergic receptors colocalize with whisker barrels in this tissue. Thus, each whisker sends a specific multisynaptic pathway to the somatosensory cortex that can be histochemically visualized and only one subtype of beta-adrenergic receptor is specifically associated with this cortical representation. Additionally, neonatal lesion of any or all of the whisker follicles results in loss of the corresponding barrel(s) as shown by histochemical markers. This loss is paralleled by a similar loss in the organization of beta 2-adrenergic receptors in the somatosensory cortex. Other results indicate that these beta 2-adrenergic receptors are not involved in moment-to-moment signal transmission in this pathway and, additionally, are not involved in a gross way in the development of whisker-barrel array

Zirconium nitride hard coatings

International Nuclear Information System (INIS)

Roman, Daiane; Amorim, Cintia Lugnani Gomes de; Soares, Gabriel Vieira; Figueroa, Carlos Alejandro; Baumvol, Israel Jacob Rabin; Basso, Rodrigo Leonardo de Oliveira

2010-01-01

Zirconium nitride (ZrN) nanometric films were deposited onto different substrates, in order to study the surface crystalline microstructure and also to investigate the electrochemical behavior to obtain a better composition that minimizes corrosion reactions. The coatings were produced by physical vapor deposition (PVD). The influence of the nitrogen partial pressure, deposition time and temperature over the surface properties was studied. Rutherford backscattering spectrometry (RBS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and corrosion experiments were performed to characterize the ZrN hard coatings. The ZrN films properties and microstructure changes according to the deposition parameters. The corrosion resistance increases with temperature used in the films deposition. Corrosion tests show that ZrN coating deposited by PVD onto titanium substrate can improve the corrosion resistance. (author)

High-temperature deformation of SiC-whisker-reinforced MgO-PSZ/mullite composites

International Nuclear Information System (INIS)

Parthasarathy, T.A.; Hay, R.S.; Ruh, R.

1996-01-01

The effect of 33.5 vol% SiC whisker loading on high-temperature deformation of 1 wt% MgO-38.5 wt% zirconia-mullite composites was studied between 1,300 and 1,400 C. At strain rates of 10 -6 to 5 x 10 -4 /s the creep resistance of zirconia-mullite composites without SiC reinforcement was inferior to monolithic mullite of similar grain size. Analysis of the results suggested that the decreased creep resistance of mullite-zirconia composites compared to pure mullite could be at least partially explained by mechanical effects of the weaker zirconia phase, increased effective diffusivity of mullite by zirconia addition, and to the differences in mullite grain morphology. With SiC whisker reinforcement, the deformation rate at high stress was nearly the same as that of the unreinforced material, but at low stress the creep rates of the SiC-reinforced material were significantly lowered. The stress dependence of the creep rate of unreinforced material suggested that diffusional creep was the operative mechanism, while the reinforced material behaved as if a threshold stress for creep existed. The threshold stress could be rationalized based on a whisker network model. This was supported by data on other whisker-containing materials; however, the threshold stress had a temperature dependence that was orders of magnitude higher than the elastic constants, leaving the physical model incomplete. The effects of residual stresses and amorphous phases at whisker/matrix interfaces are invoked to help complete the physical model for creep threshold stress

The 'whisker sign' as an indicator of ochronosis in skeletal scintigraphy

International Nuclear Information System (INIS)

Paul, R.; Ylinen, S.L.

1991-01-01

A patient with alkaptonuria and ochronotic arthrosis was imaged twice with ( 99m Tc-DPD) - once during a bout of arthritic knee pain and once when symptom-free. There was a marked accumulation of radioactivity in the large joints. During the episode of arthritis the knee joints had a higher uptake than when the patient was without symptoms. The intervertebral discs showed a high uptake which extended laterally from the axial vertebral column; the finding gave an impression of whiskers, and this 'whisker sign' may be characteristic of ochronosis. (orig.)

The Formation of Graphite Whiskers in the Primitive Solar Nebula

Science.gov (United States)

Nuth, Joseph A., III; Kimura, Yuki; Lucas, Christopher; Ferguson, Frank; Johnson, Natasha M.

2010-01-01

It has been suggested that carbonaceous grains are efficiently destroyed in the interstellar medium and must either reform in situ at very low pressures and temperatures or in an alternative environment more conducive to grain growth. Graphite whiskers have been discovered associated with high-temperature phases in meteorites such as calcium aluminum inclusions and chondrules, and it has been suggested that the expulsion of such material from proto stellar nebulae could significantly affect the optical properties of the average interstellar grain population. We have experimentally studied the potential for Fischer-Tropsch and Haber-Bosch type reactions to produce organic materials in protostellar systems from the abundant H2, CO, and N2 reacting on the surfaces of available silicate grains. When graphite grains are repeatedly exposed to H2, CO, and N2 at 875 K abundant graphite whiskers are observed to form on or from the surfaces of the graphite grains. In a dense, turbulent nebula, such extended whiskers are very likely to be broken off, and fragments could be ejected either in polar jets or by photon pressure after transport to the outer reaches of the nebula.

Whisker motor cortex reorganization after superior colliculus output suppression in adult rats.

Science.gov (United States)

Veronesi, Carlo; Maggiolini, Emma; Franchi, Gianfranco

2013-10-01

The effect of unilateral superior colliculus (SC) output suppression on the ipsilateral whisker motor cortex (WMC) was studied at different time points after tetrodotoxin and quinolinic acid injections, in adult rats. The WMC output was assessed by mapping the movement evoked by intracortical microstimulation (ICMS) and by recording the ICMS-evoked electromyographic (EMG) responses from contralateral whisker muscles. At 1 h after SC injections, the WMC showed: (i) a strong decrease in contralateral whisker sites, (ii) a strong increase in ipsilateral whisker sites and in ineffective sites, and (iii) a strong increase in threshold current values. At 6 h after injections, the WMC size had shrunk to 60% of the control value and forelimb representation had expanded into the lateral part of the normal WMC. Thereafter, the size of the WMC recovered, returning to nearly normal 12 h later (94% of control) and persisted unchanged over time (1-3 weeks). The ICMS-evoked EMG response area decreased at 1 h after SC lesion and had recovered its baseline value 12 h later. Conversely, the latency of ICMS-evoked EMG responses had increased by 1 h and continued to increase for as long as 3 weeks following the lesion. These findings provide physiological evidence that SC output suppression persistently withdrew the direct excitatory drive from whisker motoneurons and induced changes in the WMC. We suggest that the changes in the WMC are a form of reversible short-term reorganization that is induced by SC lesion. The persistent latency increase in the ICMS-evoked EMG response suggested that the recovery of basic WMC excitability did not take place with the recovery of normal explorative behaviour. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Electrochemical properties of lanthanum nitride with calcium nitride additions

International Nuclear Information System (INIS)

Lesunova, R.P.; Fishman, L.S.

1986-01-01

This paper reports on the electrochemical properties of lanthanum nitride with calcium nitride added. The lanthanum nitride was obtained by nitriding metallic lanthanum at 870 K in an ammonia stream. The product contained Cl, Pr, Nd, Sm, Fe, Ca, Cu, Mo, Mg, Al, Si, and Be. The calcium nitride was obtained by nitriding metallic calcium in a nitrogen stream. The conductivity on the LaN/C 3 N 2 system components are shown as a function of temperature. A table shows the solid solutions to be virtually electronic conductors and the lanthanum nitride a mixed conductor

Solid-state synthesis of Li{sub 4}Ti{sub 5}O{sub 12} whiskers from TiO{sub 2}-B

Energy Technology Data Exchange (ETDEWEB)

Yao, Wenjun [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, No. 5 Xin Mofan Road, Nanjing 210009 (China); Zhuang, Wei [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, No. 5 Xin Mofan Road, Nanjing 210009 (China); College of Biotechnology and Pharmaceutical Engineering, National Engineering Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816 (China); Ji, Xiaoyan [Division of Energy Science/Energy Engineering, Luleå University of Technology, Luleå 97187 Sweden (Sweden); Chen, Jingjing; Lu, Xiaohua [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, No. 5 Xin Mofan Road, Nanjing 210009 (China); Wang, Changsong, E-mail: wcs@njtech.edu.cn [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, No. 5 Xin Mofan Road, Nanjing 210009 (China)

2016-03-15

Highlights: • The Li{sub 4}Ti{sub 5}O{sub 12} whiskers were synthesized from TiO{sub 2}-B whiskers via a solid state reaction. • The TiO{sub 2}-B crystal structure for lithium diffusion is easier than anatase. • The separated diffusion and reaction process is crucial for the solid-state syntheses of Li{sub 4}Ti{sub 5}O{sub 12} whiskers. - Abstract: In this work, Li{sub 4}Ti{sub 5}O{sub 12} (LTO) was synthesized from the precursors of TiO{sub 2}-B and anatase whiskers, respectively. The synthesized LTO whiskers from TiO{sub 2}-B whiskers via a solid state reaction at 650 °C have a high degree of crystallinity with an average diameter of 300 nm. However, when anatase whiskers were used as the precursor, only particle morphology LTO was produced at 750 °C. The further analysis of the precursors, the intermediate products and the final products reveal that the crystal structure of the anatase hinders the diffusion of lithium, leading to a typical reaction–diffusion process. Under this condition, only particle morphology LTO can be produced. However, the crystal structure of the TiO{sub 2}-B is easy for lithium diffusion and the process is performed in two separated steps (i.e., diffusion and reaction), which makes it possible to decrease the solid-state reaction temperature down to 650 °C and then maintain the morphologies of whiskers.

Preparation of mullite whiskers reinforced SiC/Al2O3 composites by microwave sintering

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Wei Li

2016-12-01

Full Text Available Mullite whiskers reinforced SiC/Al2O3 composites were prepared by microwave sintering in a microwave chamber with TE666 resonant mode. Original SiC particles were coated with SiO2 using sol-gel processing and mixed with Al2O3 particles. Mullite was formed in the reaction between SiO2 and Al2O3. The isostatically pressed cylindrical pellets were sintered from 1350 °C to 1600 °C for 30 min. Physical and chemical responses were investigated by detecting changes in reflected power during the microwave sintering process. XRD was carried out to characterize the samples and showed that mullite could be formed at 1200 °C. Bridging of mullite whiskers between Al2O3 and SiC particles was observed by SEM and is due to a so-called local hot spot effect, which was the unique feature for microwave sintering. The optimized microwave sintering temperature was 1500 °C corresponding to the maximum amount of mullite whiskers within SiC/Al2O3 composites. The high electro-magnetic field enhanced the decomposition of mullite at higher temperatures above 1550 °C. The mechanical properties of mullite whiskers reinforced SiC/Al2O3 composites are much better than the SiC/Al2O3 composites without mullite whiskers.

Biopolymer nanocomposite films reinforced with nanocellulose whiskers

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Amit Saxena; Marcus Foston; Mohamad Kassaee; Thomas J. Elder; Arthur J. Ragauskas

2011-01-01

A xylan nanocomposite film with improved strength and barrier properties was prepared by a solution casting using nanocellulose whiskers as a reinforcing agent. The 13C cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) analysis of the spectral data obtained for the NCW/xylan nanocomposite films indicated the signal intensity originating...

Superconducting structure with layers of niobium nitride and aluminum nitride

International Nuclear Information System (INIS)

Murduck, J.M.; Lepetre, Y.J.; Schuller, I.K.; Ketterson, J.B.

1989-01-01

A superconducting structure is formed by depositing alternate layers of aluminum nitride and niobium nitride on a substrate. Deposition methods include dc magnetron reactive sputtering, rf magnetron reactive sputtering, thin-film diffusion, chemical vapor deposition, and ion-beam deposition. Structures have been built with layers of niobium nitride and aluminum nitride having thicknesses in a range of 20 to 350 Angstroms. Best results have been achieved with films of niobium nitride deposited to a thickness of approximately 70 Angstroms and aluminum nitride deposited to a thickness of approximately 20 Angstroms. Such films of niobium nitride separated by a single layer of aluminum nitride are useful in forming Josephson junctions. Structures of 30 or more alternating layers of niobium nitride and aluminum nitride are useful when deposited on fixed substrates or flexible strips to form bulk superconductors for carrying electric current. They are also adaptable as voltage-controlled microwave energy sources. 8 figs

Hydrothermal Preparation and Characterization of Ultralong Strontium-Substituted Hydroxyapatite Whiskers Using Acetamide as Homogeneous Precipitation Reagent

Science.gov (United States)

Xu, Jianqiang; Yang, Yaoqi; Wan, Rong; Zhang, Weibin

2014-01-01

The ultralong strontium- (Sr-) substituted hydroxyapatite (SrHAp) whiskers were successfully prepared using acetamide as homogeneous precipitation reagent. The effect of the Sr substitution amount on the lattice constants and proliferation of human osteoblast cells (MG-63) was further investigated. The results showed that the SrHAp whiskers with diameter of 0.2–12 μm and ultralong length up to 200 μm were obtained and the Sr substitution level could be facilely tailored by regulating the initial molar ratio of Sr/(Sr + Ca) in raw materials. The Sr2+ replaced part of Ca2+ and the lattice constants increased apparently with the increase of the Sr substitution amount. Compared with the pure HAp whiskers, the Sr substitution apparently stimulated the proliferation of MG-63 at certain extracted concentrations. Our study suggested that the obtained SrHAp whiskers might be used as bioactive and mechanical reinforcement materials for hard tissue regeneration applications. PMID:24592192

Repeated whisker stimulation evokes invariant neuronal responses in the dorsolateral striatum of anesthetized rats: a potential correlate of sensorimotor habits.

Science.gov (United States)

Mowery, Todd M; Harrold, Jon B; Alloway, Kevin D

2011-05-01

The dorsolateral striatum (DLS) receives extensive projections from primary somatosensory cortex (SI), but very few studies have used somesthetic stimulation to characterize the sensory coding properties of DLS neurons. In this study, we used computer-controlled whisker deflections to characterize the extracellular responses of DLS neurons in rats lightly anesthetized with isoflurane. When multiple whiskers were synchronously deflected by rapid back-and-forth movements, whisker-sensitive neurons in the DLS responded to both directions of movement. The latency and magnitude of these neuronal responses displayed very little variation with changes in the rate (2, 5, or 8 Hz) of whisker stimulation. Simultaneous recordings in SI barrel cortex and the DLS revealed important distinctions in the neuronal responses of these serially connected brain regions. In contrast to DLS neurons, SI neurons were activated by the initial deflection of the whiskers but did not respond when the whiskers moved back to their original position. As the rate of whisker stimulation increased, SI responsiveness declined, and the latencies of the responses increased. In fact, when whiskers were deflected at 5 or 8 Hz, many neurons in the DLS responded before the SI neurons. These results and earlier anatomic findings suggest that a component of the sensory-induced response in the DLS is mediated by inputs from the thalamus. Furthermore, the lack of sensory adaptation in the DLS may represent a critical part of the neural mechanism by which the DLS encodes stimulus-response associations that trigger motor habits and other stimulus-evoked behaviors that are not contingent on rewarded outcomes.

Anomalous growth of whisker-like bismuth-tin extrusions from tin-enriched tin-Bi deposits

International Nuclear Information System (INIS)

Hu, C.-C.; Tsai, Y.-D.; Lin, C.-C.; Lee, G.-L.; Chen, S.-W.; Lee, T.-C.; Wen, T.-C.

2009-01-01

This article shows the first finding that the anomalous growth of Bi-Sn extrusions from tin-enriched alloys (Sn-xBi with x between 20 and 10 wt.%) can be induced by post-plating annealing in N 2 between 145 and 260 deg. C for 10 min although metal whiskers were commonly formed on the surface of pure metals or alloys of the enriched component. From SEM observations, very similar to Sn whiskers, Bi-Sn extrusions vary in size, shape, length, and diameter with changing the annealing temperature, which are highly important in regarding the potential for failure of electronic products. Annealing resulting in thermal expansion of Sn grains is believed to squeeze the Bi-Sn alloys with relatively low melting points to form whisker-like extrusions although the exact mechanism is unclear

Whiskers de fibra de sisal obtidos sob diferentes condições de hidrólise ácida: efeito do tempo e da temperatura de extração Whiskers from sisal fibers obtained under different acid hydrolysis conditions: effect of time and temperature of extraction

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Kelcilene B. R. Teodoro

2011-01-01

Full Text Available Neste trabalho, os efeitos de diferentes condições de tempo e temperatura usados para a preparação de whiskers de sisal foram investigados com o objetivo de se determinar a influência destes parâmetros experimentais na morfologia, cristalinidade e estabilidade térmica dos materiais preparados. A obtenção dos whiskers deu-se após o pré-branqueamento da fibra de sisal com solução alcalina de peróxido de hidrogênio. A fibra branqueada foi submetida ao processo de hidrólise com solução de ácido sulfúrico 60% (m/m sob três diferentes condições de temperatura e tempos de extração: 45 °C e 60 minutos (WS45_60; 45 °C e 75 minutos (WS45_75 e 60 °C e 30 minutos (WS60_30. Os whiskers foram caracterizados quanto à morfologia por microscopia eletrônica de transmissão (MET, quanto à cristalinidade (DRX, carga superficial (potencial zeta , teor de enxofre (análise elementar e quanto à estabilidade térmica por termogravimetria (TGA. Os resultados mostraram que os whiskers de sisal apresentaram comprimento e diâmetro médios e 210 nm e 5 nm respectivamente. Devido à alta aglomeração dos whiskers, diferenças relativas às características dimensionais não puderam ser determinadas. Os resultados obtidos revelaram uma forte dependência da cristalinidade final dos whiskers com a temperatura e tempo de extração. O uso de temperatura mais alta (60 °C associado a um menor tempo de extração (30 minutos resulta em whiskers com boa estabilidade térmica (235 °C, maior cristalinidade e sem o comprometimento da estrutura cristalina da celulose.In this work, the effects of different conditions of time and temperature, used for the preparation of whiskers from sisal, were investigated to determine the influence of experimental parameters on morphology, crystallinity and thermal stability of materials prepared. The whiskers were obtained after the bleaching of sisal raw fiber with a solution of hydrogen peroxide alkaline. The

An Investigation of the Electrical Short Circuit Characteristics of Tin Whiskers

Science.gov (United States)

Courey, Karim J.

2008-01-01

Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that has a currently unknown probability associated with it. Due to contact resistance electrical shorts may not occur at lower voltage levels. In this experiment, we study the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From this data we can estimate the probability of an electrical short, as a function of voltage, given that a free tin whisker has bridged two adjacent exposed electrical conductors. Also, three tin whiskers grown from the same Space Shuttle Orbiter card guide used in the aforementioned experiment were cross-sectioned and studied using a focused ion beam (FIB). The rare polycrystalline structure seen in the FIB cross section was confirmed using transmission electron microscopy (TEM). The FIB was also used to cross section two card guides to facilitate the measurement of the grain size to determine that the tin plating on the card guides had a bright finish.

Microscopic Structure of Metal Whiskers

Science.gov (United States)

Borra, Vamsi; Georgiev, Daniel G.; Karpov, V. G.; Shvydka, Diana

2018-05-01

We present TEM images of the interior of metal whiskers (MWs) grown on electroplated Sn films. Along with earlier published information, our observations focus on a number of questions, such as, why MWs' diameters are in the micron range (significantly exceeding the typical nanosizes of nuclei in solids), why the diameters remain practically unchanged in the course of MW growth, what the nature of MW diameter stochasticity is, and what the origin of the well-known striation structure of MW side surfaces is. In an attempt to address such questions, we perform an in-depth study of MW structure at the nanoscale by detaching a MW from its original film, reducing its size to a thin slice by cutting its sides by a focused ion beam, and performing TEM on that structure. Also, we examine the root of the MW and Cu-Sn interface for the intermetallic compounds. Our TEM observations reveal a rich nontrivial morphology suggesting that MWs may consist of many side-by-side grown filaments. This structure appears to extend to the outside whisker surface and be the reason for the striation. In addition, we put forward a theory where nucleation of multiple thin metal needles results in micron-scale and larger MW diameters. This theory is developed in the average field approximation similar to the roughening transitions of metal surfaces. The theory also predicts MW nucleation barriers and other observed features.

Technics Research on Polycrystalline Cubic Boron Nitride Cutting Tools Dry Turning Ti-6AL-4V Alloy Based on Orthogonal Experimental Design

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Jia Yunhai

2018-01-01

Full Text Available Ti-6Al-4V components are the most widely used titanium alloy products not only in the aerospace industry, but also for bio-medical applications. The machine-ability of titanium alloys is impaired by their high temperature chemical reactivity, low thermal conductivity and low modulus of elasticity. Polycrystalline cubic boron nitride represents a substitute tool material for turning titanium alloys due to its high hardness, wear resistance, thermal stability and hot red hardness. For determination of suitable cutting parameters in dry turning Ti-6AL-4V alloy by Polycrystalline cubic boron nitride cutting tools, the samples, 300mm in length and 100mm in diameter, were dry machined in a lathe. The turning suitable parameters, such as cutting speed, feed rate and cut depth were determined according to workpieces surface roughness and tools flank wear based on orthogonal experimental design. The experiment showed that the cutting speed in the range of 160~180 m/min, the feed rate is 0.15 mm/rev and the depth of cut is 0.20mm, ideal workpiece surface roughness and little cutting tools flank wear can be obtained.

Spectra of soft X-ray excitation potentials of titanium and vanadium compounds with carbon and nitrogen of a variable composition

International Nuclear Information System (INIS)

Brytov, I.A.; Bleher, B. Eh.; Neshpor, V.S.

1979-01-01

Lsub(3,2) spectra of excitation potentials (SEP) of a soft X-ray radiation of titanium and vanadium carbides and titanium nitrides in their homogeneity range, as well as solid solutions of nitrogen in α-titanium, are studied. The binding energies of electrons of the exciting levels relatively to the Fermi level are determined, adequacy of different quantomechanical calculations is experimentally proved. The observed changes in SEP at the variation of the metalloid concentration are explained by a quantitative transformation model of valent state energetic spectra when metalloid vacancies and connected with them local levels form

Synthesis of carbon nitride powder by selective etching of TiC0.3N0.7 in chlorine-containing atmosphere at moderate temperature

International Nuclear Information System (INIS)

Sui Jian; Lu Jinjun

2010-01-01

We reported the synthesis of carbon nitride powder by extracting titanium from single inorganic precursor TiC 0.3 N 0.7 in chlorine-containing atmosphere at ambient pressure and temperature not exceeding 500 deg. C. The TiC 0.3 N 0.7 crystalline structure acted as a template, supplying active carbon and nitrogen atoms for carbon nitride when it was destroyed in chlorination. X-ray diffraction data showed that the obtained carbon nitride powders were amorphous, which was in good agreement with transmission electron microscope analysis. The composition and structure of carbon nitride powders were analyzed by employing Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Results indicated that disorder structure was most likely for the carbon nitride powders and the N content depended greatly on the chlorination temperature. Thermal analysis in flowing N 2 indicated that the mass loss started from 300 deg. C and the complete decomposition occurred at around 650 deg. C, confirming the low thermal stability of the carbon nitride material.

The role of whiskers in compensation of visual deficit in a mouse model of retinal degeneration.

Science.gov (United States)

Voller, Jaroslav; Potužáková, Barbora; Šimeček, Vojtěch; Vožeh, František

2014-01-13

Sensory deprivation in one modality can enhance the development of the remaining modalities via mechanisms of synaptic plasticity. Mice of the C3H strain suffer from RD1 retinal degeneration that leads to visual impairment at weaning age. We examined a role of whiskers in compensation of the visual deficit. In order to differentiate the contribution of the whiskers from other mechanisms that can take part in the compensation, we investigated the effect of both chronic and acute tactile deprivation. Three-month-old mice were used. We examined motor skills (rotarod, beam walking test), gait control (CatWalk system), spontaneous motor activity (open field) and CNS excitability to an acoustic stimulus for assessment of compensatory changes in auditory system (audiogenic epilepsy). In the sighted mice, the only effect was a decline in their rotarod test performance after acute whisker removal. In the blind animals, chronic tactile deprivation caused changes in their gait and impaired the performance in motor tests. Some other compensatory mechanisms were involved but the whiskers are essential for the compensation as it emerged from more marked change of gait and the worsening of the motor performance after the acute whisker removal. Both chronic and acute tactile deprivation induced anxiety-like behaviour. Only a combination of blindness and chronic tactile deprivation led to an increased sense of hearing. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Evaluation and silicon nitride internal combustion engine components. Final report, Phase I

Energy Technology Data Exchange (ETDEWEB)

Voldrich, W. [Allied-Signal Aerospace Co., Torrance, CA (United States). Garrett Ceramic Components Div.

1992-04-01

The feasibility of silicon nitride (Si{sub 3}N{sub 4}) use in internal combustion engines was studied by testing three different components for wear resistance and lower reciprocating mass. The information obtained from these preliminary spin rig and engine tests indicates several design changes are necessary to survive high-stress engine applications. The three silicon nitride components tested were valve spring retainers, tappet rollers, and fuel pump push rod ends. Garrett Ceramic Components` gas-pressure sinterable Si{sub 3}N{sub 4} (GS-44) was used to fabricate the above components. Components were final machined from densified blanks that had been green formed by isostatic pressing of GS-44 granules. Spin rig testing of the valve spring retainers indicated that these Si{sub 3}N{sub 4} components could survive at high RPM levels (9,500) when teamed with silicon nitride valves and lower spring tension than standard titanium components. Silicon nitride tappet rollers showed no wear on roller O.D. or I.D. surfaces, steel axles and lifters; however, due to the uncrowned design of these particular rollers the cam lobes indicated wear after spin rig testing. Fuel pump push rod ends were successful at reducing wear on the cam lobe and rod end when tested on spin rigs and in real-world race applications.

Structural characterization of thin films of titanium nitride deposited by laser ablation; Caracterizacion estructural de peliculas delgadas de nitruro de titanio depositadas por ablacion laser

Energy Technology Data Exchange (ETDEWEB)

Castro C, M.A.; Escobar A, L.; Camps C, E.; Mejia H, J.A. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

2004-07-01

Thin films of titanium nitride were deposited using the technique of laser ablation. It was studied the effect of the density of laser energy used for ablation the target as well as of the pressure of the work gas about the structure and the hardness of the deposited thin films. Depending on the pressure of the work gas films was obtained with preferential orientation in the directions (200) and (111). At a pressure of 1 x 10{sup -2} Torr only the direction (200) was observed. On the other hand to the pressure of 5 x 10{sup -3} Torr the deposited material this formed by a mixture of the orientation (200) and (111), being the direction (111) the predominant one. Thin films of Ti N were obtained with hardness of up to 24.0 GPa that makes to these attractive materials for mechanical applications. The hardness showed an approximately linear dependence with the energy density. (Author)

Estimating the Probability of Electrical Short Circuits from Tin Whiskers. Part 2

Science.gov (United States)

Courey, Karim J.; Asfour, Shihab S.; Onar, Arzu; Bayliss, Jon A.; Ludwig, Larry L.; Wright, Maria C.

2010-01-01

To comply with lead-free legislation, many manufacturers have converted from tin-lead to pure tin finishes of electronic components. However, pure tin finishes have a greater propensity to grow tin whiskers than tin-lead finishes. Since tin whiskers present an electrical short circuit hazard in electronic components, simulations have been developed to quantify the risk of said short circuits occurring. Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that had an unknown probability associated with it. Note however that due to contact resistance electrical shorts may not occur at lower voltage levels. In our first article we developed an empirical probability model for tin whisker shorting. In this paper, we develop a more comprehensive empirical model using a refined experiment with a larger sample size, in which we studied the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From the resulting data we estimated the probability distribution of an electrical short, as a function of voltage. In addition, the unexpected polycrystalline structure seen in the focused ion beam (FIB) cross section in the first experiment was confirmed in this experiment using transmission electron microscopy (TEM). The FIB was also used to cross section two card guides to facilitate the measurement of the grain size of each card guide's tin plating to determine its finish .

Two whisker motor areas in the rat cortex: evidence from thalamocortical connections.

Science.gov (United States)

Mohammed, Hisham; Jain, Neeraj

2014-02-15

In primates, the motor cortex consists of at least seven different areas, which are involved in movement planning, coordination, initiation, and execution. However, for rats, only the primary motor cortex has been well described. A rostrally located second motor area has been proposed, but its extent, organization, and even definitive existence remain uncertain. Only a rostral forelimb area (RFA) has been definitively described, besides few reports of a rostral hindlimb area. We have previously proposed existence of a second whisker area, which we termed the rostral whisker area (RWA), based on its differential response to intracortical microstimulation compared with the caudal whisker area (CWA) in animals under deep anesthesia (Tandon et al. [2008] Eur J Neurosci 27:228). To establish that RWA is distinct from the caudally contiguous CWA, we determined sources of thalamic inputs to the two proposed whisker areas. Sources of inputs to RFA, caudal forelimb area (CFA), and caudal hindlimb region were determined for comparison. The results show that RWA and CWA can be distinguished based on differences in their thalamic inputs. RWA receives major projections from mediodorsal and ventromedial nuclei, whereas the major projections to CWA are from the ventral anterior, ventrolateral, and posterior nuclei. Moreover, the thalamic nuclei that provide major inputs to RWA are the same as for RFA, and the nuclei projecting to CWA are same as for CFA. The results suggest that rats have a second rostrally located motor area with RWA and RFA as its constituents. Copyright © 2013 Wiley Periodicals, Inc.

Repeated whisker stimulation evokes invariant neuronal responses in the dorsolateral striatum of anesthetized rats: a potential correlate of sensorimotor habits

OpenAIRE

Mowery, Todd M.; Harrold, Jon B.; Alloway, Kevin D.

2011-01-01

The dorsolateral striatum (DLS) receives extensive projections from primary somatosensory cortex (SI), but very few studies have used somesthetic stimulation to characterize the sensory coding properties of DLS neurons. In this study, we used computer-controlled whisker deflections to characterize the extracellular responses of DLS neurons in rats lightly anesthetized with isoflurane. When multiple whiskers were synchronously deflected by rapid back-and-forth movements, whisker-sensitive neur...

Neurons within the trigeminal mesencephalic nucleus encode for the kinematic parameters of the whisker pad macrovibrissae.

Science.gov (United States)

Mameli, Ombretta; Caria, Marcello A; Biagi, Francesca; Zedda, Marco; Farina, Vittorio

2017-05-01

It has been recently shown in rats that spontaneous movements of whisker pad macrovibrissae elicited evoked responses in the trigeminal mesencephalic nucleus (Me5). In the present study, electrophysiological and neuroanatomical experiments were performed in anesthetized rats to evaluate whether, besides the whisker displacement per se, the Me5 neurons are also involved in encoding the kinematic properties of macrovibrissae movements, and also whether, as reported for the trigeminal ganglion, even within the Me5 nucleus exists a neuroanatomical representation of the whisker pad macrovibrissae. Extracellular electrical activity of single Me5 neurons was recorded before, during, and after mechanical deflection of the ipsilateral whisker pad macrovibrissae in different directions, and with different velocities and amplitudes. In several groups of animals, single or multiple injections of the tracer Dil were performed into the whisker pad of one side, in close proximity to the vibrissae follicles, in order to label the peripheral terminals of the Me5 neurons innervating the macrovibrissae (whisking-neurons), and therefore, the respective perikaria within the nucleus. Results showed that: (1) the whisker pad macrovibrissae were represented in the medial-caudal part of the Me5 nucleus by a single cluster of cells whose number seemed to match that of the macrovibrissae; (2) macrovibrissae mechanical deflection elicited significant responses in the Me5 whisking-neurons, which were related to the direction, amplitude, and frequency of the applied deflection. The specific functional role of Me5 neurons involved in encoding proprioceptive information arising from the macrovibrissae movements is discussed within the framework of the whole trigeminal nuclei activities. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Galvano-magnetic properties and Shubnikov de Haas effect of Te-whiskers

International Nuclear Information System (INIS)

Berezovets, Veacheslav; Bondarchuk, Nikolai; Nikolaeva, Albina; Nijankovskii, Victor

2009-01-01

The work is devoted to investigation of the peculiarities of magnetoresistance, Hall effect and Shubnikov de Haas oscillations in Te-whiskers. Te-whiskers was prepared from vapor-gas phase on the substrate pure tellurium and grown naturally, of the walls of a crucible in the course of growing Te single crystals by the Czochralski method . The measurements of the galvanomagnetic properties and Shubnikov de Haas oscillation correspond to the notion of the occurrence of the effect of intraband magnetic breakdown when two different quasi-classical cyclotron trajectories coexist simultaneously in a magnetic field. This effect is a consequence of the presence of the saddle point in the dispersion law of the tellurium valence band. (authors)

The 'whisker sign' as an indicator of ochronosis in skeletal scintigraphy

Energy Technology Data Exchange (ETDEWEB)

Paul, R.; Ylinen, S.L. (Turku Univ. (Finland). Dept. of Nuclear Medicine)

1991-03-01

A patient with alkaptonuria and ochronotic arthrosis was imaged twice with ({sup 99m}Tc-DPD) - once during a bout of arthritic knee pain and once when symptom-free. There was a marked accumulation of radioactivity in the large joints. During the episode of arthritis the knee joints had a higher uptake than when the patient was without symptoms. The intervertebral discs showed a high uptake which extended laterally from the axial vertebral column; the finding gave an impression of whiskers, and this 'whisker sign' may be characteristic of ochronosis. (orig.).

[Effect of niobium nitride on the bonding strength of titanium porcelain by magnetron sputtering].

Science.gov (United States)

Wang, Shu-shu; Zhang, La-bao; Guang, Han-bing; Zhou, Shu; Zhang, Fei-min

2010-05-01

To investigate the effect of magnetron sputtered niobium nitride (NbN) on the bonding strength of commercially pure cast titanium (Ti) and low-fusing porcelain (Ti/Vita titankeramik system). Sixty Ti specimens were randomly divided into four groups, group T1, T2, T3 and T4. All specimens of group T1 and T2 were first treated with 120 microm blasted Al2O3 particles, and then only specimens of group T2 were treated with magnetron sputtered NbN film. All specimens of group T3 and T4 were first treated with magnetron sputtered NbN film and then only specimens of group T4 were treated with 120 microm blasted Al2O3 particles. The composition of the deposits were analyzed by X-ray diffraction (XRD). A universal testing machine was used to perform the three-point bending test to evaluate the bonding strength of Ti and porcelain. The microstructure of NbN, the interface of Ti-porcelain and the fractured Ti surface were observed with scanning electron microscopy (SEM) and energy depressive spectrum (EDS), and the results were compared. The XRD results showed that the NbN deposits were cubic crystalline phases. The bonding strength of Ti and porcelain in T1 to T4 group were (27.2+/-0.8), (43.1+/-0.6), (31.4+/-1.0) and (44.9+/-0.6) MPa. These results were analyzed by one-way analysis of variance and differences between groups were compared using least significant difference test. Significant inter-group differences were found among all groups (Pporcelain, while samples treated with both Al2O3 and NbN had better bond. EDS of Ti-porcelain interface showed oxidation occurred in T1, T2 and T3, but was well controlled in T4. Magnetron sputtered NbN can prevent Ti from being oxidized, and can improve the bonding strength of Ti/Vita titankeramik system. Al2O3 blast can also improve the bonding strength of Ti/Vita titankeramik system.

Reinforcement of thermoplastic chitosan hydrogel using chitin whiskers optimized with response surface methodology.

Science.gov (United States)

Sun, Guohui; Zhang, Xin; Bao, Zixian; Lang, Xuqian; Zhou, Zhongzheng; Li, Yang; Feng, Chao; Chen, Xiguang

2018-06-01

To strengthen the mechanical strength of thermo-sensitive hydroxybutyl chitosan (HBC) hydrogel, chitin whiskers were used as sticker to fabricate reinforced HBC (HBCW) hydrogel by using response surface methodology. Unlike the intrinsic network of HBC hydrogel, HBCW hydrogel showed a laminar shape with firm structure. The preparation condition was optimized by three-factor-three-level Box-Behnken design. The maximum mechanical strength (1011.11 Pa) was achieved at 50 °C, when the concentrations of HBC and chitin whiskers were 5.1 wt% and 2.0 wt%, respectively. The effects of temperature, pH value and NaCl concentration on mechanical strength of HBCW hydrogels were investigated via the oscillatory stress sweeps. The results showed that HBCW hydrogel could reach the maximum stiffness (∼1126 Pa) at 37 °C pH 12.0. Low pH and high salty ions could decrease the stability of hydrogel, while chitin whiskers could increase the stress tolerance and related ruptured strain of HBCW hydrogels. Copyright © 2018. Published by Elsevier Ltd.

Silicon carbide whisker reinforced composites and method for making same

Science.gov (United States)

Wei, G.C.

1984-02-09

The present invention is directed to the fabrication of ceramic composites which possess improved mechanical properties, especially increased fracture toughness. In the formation of these ceramic composites, the single-crystal SiC whiskers are mixed with fine ceramic powders of a ceramic material such as Al/sub 2/O/sub 3/, mullite, or B/sub 4/C. The mixtures which contain a homogeneous dispersion of the SiC whiskers are hot pressed at pressures in a range of about 28 to 70 MPa and temperatures in the range of about 1600 to 1950/sup 0/C with pressing times varying from about 0.75 to 2.5 hours. The resulting ceramic composites show an increase in fracture toughness of up to about 9 MPa.m/sup 1/2/ which represents as much as a two-fold increase over that of the matrix material.

Extraction and characterization of cellulose nano whiskers from balsa wood

International Nuclear Information System (INIS)

Morelli, Carolina L.; Bretas, Rosario E.S.; Marconcini, Jose M.; Pereira, Fabiano V.; Branciforti, Marcia C.

2011-01-01

In this study cellulose nano whiskers were obtained from balsa wood. For this purpose, fibers of balsa wood were subjected to hydrolysis reactions for lignin and hemi cellulose digestion and acquisition of nano-scale cellulose. Cellulose nano crystals obtained had medium length and thickness of 176 nm and 7 nm respectively. Infrared spectroscopy and x-ray diffraction showed that the process used for extracting nano whiskers could digest nearly all the lignin and hemi cellulose from the balsa fiber and still preserve the aspect ratio and crystallinity, satisfactory enough for future application in polymer nano composites. Thermogravimetry showed that the onset temperature of thermal degradation of cellulose nano crystals (226 degree C) was higher than the temperature of the balsa fiber (215 degree C), allowing its use in molding processes with many polymers from the molten state.(author)

Laser processing of in situ TiN/Ti composite coating on titanium.

Science.gov (United States)

Sahasrabudhe, Himanshu; Soderlind, Julie; Bandyopadhyay, Amit

2016-01-01

Laser remelting of commercially pure titanium (CP-Ti) surface was done in a nitrogen rich inert atmosphere to form in situ TiN/Ti composite coating. Laser surface remelting was performed at two different laser powers of 425 W and 475 W. At each power, samples were fabricated with one or two laser scans. The resultant material was a nitride rich in situ coating that was created on the surface. The cross sections revealed a graded microstructure. There was presence of nitride rich dendrites dispersed in α-Ti matrix at the uppermost region. The structure gradually changed with lesser dendrites and more heat affected α-Ti phase maintaining a smooth interface. With increasing laser power, the dendrites appeared to be larger in size. Samples with two laser scans showed discontinuous dendrites and more α-Ti phase as compared to the samples with one laser scan. The resultant composite of TiN along with Ti2N in α-Ti showed substantially higher hardness and wear resistance than the untreated CP-Ti substrate. Coefficient of friction was also found to reduce due to surface nitridation. Leaching of Ti(4+) ions during wear test in DI water medium was found to reduce due to laser surface nitriding. Copyright © 2015 Elsevier Ltd. All rights reserved.

Nitride alloy layer formation of duplex stainless steel using nitriding process

Science.gov (United States)

Maleque, M. A.; Lailatul, P. H.; Fathaen, A. A.; Norinsan, K.; Haider, J.

2018-01-01

Duplex stainless steel (DSS) shows a good corrosion resistance as well as the mechanical properties. However, DSS performance decrease as it works under aggressive environment and at high temperature. At the mentioned environment, the DSS become susceptible to wear failure. Surface modification is the favourable technique to widen the application of duplex stainless steel and improve the wear resistance and its hardness properties. Therefore, the main aim of this work is to nitride alloy layer on the surface of duplex stainless steel by the nitriding process temperature of 400°C and 450°C at different time and ammonia composition using a horizontal tube furnace. The scanning electron microscopy and x-ray diffraction analyzer are used to analyse the morphology, composition and the nitrided alloy layer for treated DSS. The micro hardnesss Vickers tester was used to measure hardness on cross-sectional area of nitrided DSS. After nitriding, it was observed that the hardness performance increased until 1100 Hv0.5kgf compared to substrate material of 250 Hv0.5kgf. The thickness layer of nitride alloy also increased from 5μm until 100μm due to diffusion of nitrogen on the surface of DSS. The x-ray diffraction results showed that the nitride layer consists of iron nitride, expanded austenite and chromium nitride. It can be concluded that nitride alloy layer can be produced via nitriding process using tube furnace with significant improvement of microstructural and hardness properties.

Stoichiometric carbon nitride synthesized by ion beam sputtering and post nitrogen ion implantation

International Nuclear Information System (INIS)

Valizadeh, R.; Colligon, J.S.; Katardiev, I.V.; Faunce, C.A.; Donnelly, S.E.

1998-01-01

Full text: Carbon nitride films have been deposited on Si (100) by ion beam sputtering a vitreous graphite target with nitrogen and argon ions with and without concurrent N2 ion bombardment at room temperature. The sputtering beam energy was 1000 eV and the assisted beam energy was 300 eV with ion / atom arrival ratio ranging from 0.5 to 5. The carbon nitride films were deposited both as single layer directly on silicon substrate and as multilayer between two layers of stoichiometric amorphous silicon nitride and polycrystalline titanium nitride. The deposited films were implanted ex-situ with 30 keV nitrogen ions with various doses ranging from 1E17 to 4E17 ions.cm -2 and 2 GeV xenon ion with a dose of 1E12 ions.cm -2 . The nitrogen concentration of the films was measured with Rutherford Backscattering (RBS), Secondary Neutral Mass Spectrometry (SNMS) and Parallel Electron Energy Loss Spectroscopy (PEELS). The nitrogen concentration for as deposited sample was 34 at% and stoichiometric carbon nitride C 3 N 4 was achieved by post nitrogen implantation of the multi-layered films. Post bombardment of single layer carbon nitride films lead to reduction in the total nitrogen concentration. Carbon K edge structure obtained from PEELS analysis suggested that the amorphous C 3 N 4 matrix was predominantly sp 2 bonded. This was confirmed by Fourier Transforrn Infra-Red Spectroscopy (FTIR) analysis of the single CN layer which showed the nitrogen was mostly bonded with carbon in nitrile (C≡N) and imine (C=N) groups. The microstructure of the film was determined by Transmission Electron Microscopy (TEM) which indicated that the films were amorphous

Electrochemical preparation of Al–Sm intermetallic compound whisker in LiCl–KCl Eutectic Melts

International Nuclear Information System (INIS)

Ji, De−Bin; Yan, Yong−De; Zhang, Mi−Lin; Li, Xing; Jing, Xiao−Yan; Han, Wei; Xue, Yun; Zhang, Zhi−Jian; Hartmann, Thomas

2015-01-01

Highlights: • The reduction process of Sm(III) was investigated in LiCl–KCl melt on an aluminum electrode at 773 K. • Al–Sm alloy with different phase structure (Al 2 Sm and Al 3 Sm) was prepared by potentiostatic electrolysis on an aluminum electrode with the change of electrolytic potentials and time in LiCl–KCl–SmCl 3 melts. • Al − Sm alloy containing whiskers (Al 4 Sm) was obtained by potentiostatic electrolysis (−2.10 V) on an aluminum electrode for 7 hours with the change of electrolytic temperature and cooling rate in LiCl–KCl–SmCl 3 (16.5 wt. %) melts. The results from micro–hardness test and potentiodynamic polarization test show the micro hardness and corrosion property are remarkably improved with the help of Al–Sm intermetallic compound whiskers. - Abstract: This work presents the electrochemical study of Sm(III) on an aluminum electrode in LiCl–KCl melts at 773 K by different electrochemical methods. Three electrochemical signals in cyclic voltammetry, square wave voltammetry, open circuit chronopotentiometry, and cathode polarization curve are attributed to different kinds of Al–Sm intermetallic compounds, Al 2 Sm, Al 3 Sm, and Al 4 Sm, respectively. Al–Sm alloy with different phase structure (Al 2 Sm and Al 3 Sm) could be obtained by the potentiostatic electrolysis with the change of electrolytic potentials and time. Al–Sm alloy containing whiskers (Al 4 Sm) was obtained by potentiostatic electrolysis (−2.10 V) on an aluminum electrode for 7 hours with the change of electrolytic temperature and cooling rate in LiCl–KCl–SmCl 3 (16.5 wt. %) melts. The XRD and SEM&EDS were employed to investigate the phase composition and microstructure of Al–Sm alloy. SEM analysis shows that lots of needle−like precipitates formed in Al–Sm alloy, and their ratios of length to diameter are found to be greater than 10 to 1. The TEM and electron diffraction pattern were performed to investigate the crystal structure of the

Macrophage proinflammatory response to the titanium alloy equipment in dental implantation.

Science.gov (United States)

Chen, X; Li, H S; Yin, Y; Feng, Y; Tan, X W

2015-08-07

Titanium alloy and stainless steel (SS) had been widely used as dental implant materials because of their affinity with epithelial tissue and connective tissue, and good physical, chemical, biological, mechanical properties and processability. We compared the effects of titanium alloy and SS on macrophage cytokine expression as well as their biocompatibility. Mouse macrophage RAW264.7 cells were cultured on titanium alloy and SS surfaces. Cells were counted by scanning electron microscopy. A nitride oxide kit was used to detect released nitric oxide by macrophages on the different materials. An enzyme linked immunosorbent assay was used to detect monocyte chemoattractant protein-1 levels. Scanning electron microscopy revealed fewer macrophages on the surface of titanium alloy (48.2 ± 6.4 x 10(3) cells/cm(2)) than on SS (135 ± 7.3 x 10(3) cells/cm(2)). The nitric oxide content stimulated by titanium alloy was 22.5 mM, which was lower than that stimulated by SS (26.8 mM), but the difference was not statistically significant (P = 0.07). The level of monocyte chemoattractant protein-1 released was significantly higher in the SS group (OD value = 0.128) than in the titanium alloy group (OD value = 0.081) (P = 0.024). The transforming growth factor-b1 mRNA expression levels in macrophages after stimulation by titanium alloy for 12 and 36 h were significantly higher than that after stimulation by SS (P = 0.31 and 0.25, respectively). Macrophages participate in the inflammatory response by regulating cytokines such as nitric oxide, monocyte chemoattractant protein-1, and transforming growth factor-b1. There were fewer macrophages and lower inflammation on the titanium alloy surface than on the SS surface. Titanium alloy materials exhibited better biological compatibility than did SS.

Tin Whisker Electrical Short Circuit Characteristics. Part 2

Science.gov (United States)

Courey, Karim J.; Asfour, Shihab S.; Onar, Arzu; Bayliss, Jon A.; Ludwig, Lawrence L.; Wright, Maria C.

2009-01-01

Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that has an unknown probability associated with it. Note however that due to contact resistance electrical shorts may not occur at lower voltage levels. In our first article we developed an empirical probability model for tin whisker shorting. In this paper, we develop a more comprehensive empirical model using a refined experiment with a larger sample size, in which we studied the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From the resulting data we estimated the probability distribution of an electrical short, as a function of voltage. In addition, the unexpected polycrystalline structure seen in the focused ion beam (FIB) cross section in the first experiment was confirmed in this experiment using transmission electron microscopy (TEM). The FIB was also used to cross section two card guides to facilitate the measurement of the grain size of each card guide's tin plating to determine its finish.

Fabrication and characterization of intrinsic Josephson junctions in RE-123 whiskers

International Nuclear Information System (INIS)

Okutsu, T.; Ueda, S.; Ishii, S.; Nagasawa, M.; Takano, Y.

2008-01-01

The series of REBa 2 Cu 3 O 7-δ RE-123; RE = Y, Eu, Gd, Dy, Ho, Er, Tm, and Lu) single-crystal whiskers have been successfully grown using the Te- or Sb-doping method. Intrinsic Josephson junctions (IJJs) were fabricated from the whiskers using a focused ion beam (FIB). As-grown IJJs with T c > 70 K showed a Josephson current but no multi-branches in the current-voltage (I-V) characteristics. Under-doped specimens were obtained by a post-annealing process. As-grown IJJs with lower T c and all the specimens of the post-annealed IJJs showed clear multi-branched structure. The post-annealing reduced the critical temperature (T c ) and the critical current density (J c ) of the IJJs, and increased the anisotropic parameter γ

Carbon dioxide ion implantation in Titanium Nitride (Ti N)

International Nuclear Information System (INIS)

Torabi, Sh.; Sari, A. H.; Hojabri, A.; Ghoranneviss, M.

2007-01-01

Nitrogen ion implantation on titanium samples performed at 3x10 18 , 8x10 17 , 3x10 18 doses. In addition CO 2 ions were also implanted at doses in the range of 1x10 17 ,4 x10 17 ,8x10 17 . Atomic Force Microscopy, used to investigate the topographical changes of implanted samples. The structure of samples and phase composition were characterized using x-ray diffraction. The results show that by increasing of nitrogen ions, the roughness, grain sizes and hardness will increase. But by further increasing of dose, hardness will be decreased. The CO 2 implantation also enhance the roughness, grain size and hardness which could be caused by phase composition.

Fabricação de compósitos com matriz de alumina reforçada com whiskers de mulita

OpenAIRE

Salles, Mário César Fernandez de

2008-01-01

Neste trabalho foram fabricados compósitos cerâmicos utilizando alumina como matriz e whiskers de mulita como reforço. As composições de whiskers foram 10, 20, 30 e 40% em peso. Os whiskers de mulita utilizados como matérias-primas foram obtidos através do tratamento térmico do mineral topázio incolor no Laboratório de Tratamento Térmico de Materiais do ICEB/UFOP. A alumina de elevada pureza foi fornecida pela empresa Alfa Apesar. As matérias primas, após serem pesadas, foram submetidas a um ...

Surface Modification of C17200 Copper-Beryllium Alloy by Plasma Nitriding of Cu-Ti Gradient Film

Science.gov (United States)

Zhu, Y. D.; Yan, M. F.; Zhang, Y. X.; Zhang, C. S.

2018-03-01

In the present work, a copper-titanium film of gradient composition was firstly fabricated by the dual magnetron sputtering through power control and plasma nitriding of the film was then conducted to modify C17200 Cu alloy. The results showed that the prepared gradient Cu-Ti film by magnetron sputtering was amorphous. After plasma nitriding at 650 °C, crystalline Cu-Ti intermetallics appeared in the multi-phase coating, including CuTi2, Cu3Ti, Cu3Ti2 and CuTi. Moreover, even though the plasma nitriding duration of the gradient Cu-Ti film was only 0.5 h, the mechanical properties of the modified Cu surface were obviously improved, with the surface hardness enhanced to be 417 HV0.01, the wear rate to be 0.32 × 10-14 m3/Nm and the friction coefficient to be 0.075 at the load of 10 N, which are all more excellent than the C17200 Cu alloy. In addition, the wear mechanism also changed from adhesion wear for C17200 Cu substrate to abrasive wear for the modified surface.

Effect of heating parameters on sintering behaviors and properties of mullite whisker frameworks

Science.gov (United States)

Zhang, Y. M.; Zeng, D. J.; Wang, B.; Yang, J. F.

2018-04-01

Mullite whisker frameworks were fabricated by vapor-solid reaction with SiO2, Al2O3 and AlF3 powders as the whisker forming agent at high temperatures. The effects of heating temperature and soaking time on the weight loss, liner shrinkage, porosity, microstructure and compressive strength were investigated. The results showed that with the increasing of the sintering temperature and soaking time, the weight loss and liner shrinkage of the samples increased and the porosities decreased due to the accelerated vapor-solid reaction, resulting in strong bonding and grain growth of the mullite frameworks. The compressive strength of the samples increased with increasing the sintering temperature from 1500 to 1650 °C, and decreased with the soaking time extended to more than 5 h for 1500 °C and 2 h for 1650 °C. A maximum compressive strength of 142 MPa at a porosity of 62.3% was obtained for the mullite whisker framework heated at 1500 °C for 5 h. The enhanced strength was attributed to the strong bonding strength and fine mullite grains resulting from a relative lower heating temperature and a modest soaking time.

An Empirical Model for Estimating the Probability of Electrical Short Circuits from Tin Whiskers-Part I

Science.gov (United States)

Courey, Karim; Wright, Clara; Asfour, Shihab; Bayliss, Jon; Ludwig, Larry

2008-01-01

Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that has a currently unknown probability associated with it. Due to contact resistance, electrical shorts may not occur at lower voltage levels. In this experiment, we study the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From this data, we can estimate the probability of an electrical short, as a function of voltage, given that a free tin whisker has bridged two adjacent exposed electrical conductors. In addition, three tin whiskers grown from the same Space Shuttle Orbiter card guide used in the aforementioned experiment were cross sectioned and studied using a focused ion beam (FIB).

Fabrication and properties of aluminum silicate fibrous materials with in situ synthesized K2Ti6O13 whiskers

Science.gov (United States)

Liu, Hao; Wei, Nan; Wang, Zhou-fu; Wang, Xi-tang; Ma, Yan

2017-11-01

To improve their mechanical and thermal insulation properties, aluminum silicate fibrous materials with in situ synthesized K2Ti6O13 whiskers were prepared by firing a mixture of short aluminum silicate fibers and gel powders obtained from a sol-gel process. During the preparation process, the fiber surface was coated with K2Ti6O13 whiskers after the fibers were subjected to a heat treatment carried out at various temperatures. The effects of process parameters on the microstructure, compressive strength, and thermal conductivity were analyzed systematically. The results show that higher treatment temperatures and longer treatment durations promoted the development of K2Ti6O13 whiskers on the surface of aluminum silicate fibers; in addition, the intersection structure between whiskers modulated the morphology and volume of the multi-aperture structure among fibers, substantially increasing the fibers' compressive strength and reducing their heat conduction and convective heat transfer at high temperatures.

Conversion of wood flour/SiO2/phenolic composite to porous SiC ceramic containing SiC whiskers

Directory of Open Access Journals (Sweden)

Li Zhong

2013-01-01

Full Text Available A novel wood flour/SiO2/phenolic composite was chosen to be converted into porous SiC ceramic containing SiC whiskers via carbothermal reduction. At 1550°C the composite is converted into porous SiC ceramic with pore diameters of 10~40μm, and consisting of β-SiC located at the position of former wood cell walls. β-SiC wire-like whiskers of less than 50 nm in diameter and several tens to over 100 μm in length form within the pores. The surface of the resulting ceramic is coated with β-SiC necklace-like whiskers with diameters of 1~2μm.

Crystalline instability of Bi-2212 superconducting whiskers near room temperature

International Nuclear Information System (INIS)

Cagliero, Stefano; Khan, Mohammad Mizanur Rahman; Agostino, Angelo; Truccato, Marco; Orsini, Francesco; Marinone, Massimo; Poletti, Giulio; Lascialfari, Alessandro

2009-01-01

We report new evidences for the thermodynamic instability of whisker crystals in the Bi-Sr-Ca-Cu-O (BSCCO) system. Annealing treatments at 90 C have been performed on two sets of samples, which were monitored by means of X-rays diffraction (XRD) and atomic force microscopy (AFM) measurements, respectively. Two main crystalline domains of Bi 2 Sr 2 CuCa 2 O 8+x (Bi-2212) were identified in the samples by the XRD data, which underwent an evident crystalline segregation after about 60 hours. Very fast dynamics of the surface modifications was also described by the AFM monitoring. Two typologies of surface structures formed after about 3 annealing hours: continuous arrays of dome shaped bodies were observed along the edges of the whiskers, while in the central regions a dense texture of flat bodies was found. These modifications are described in terms of the formation of simple oxide clusters involving a degradation of the internal layers. (orig.)

Crystalline instability of Bi-2212 superconducting whiskers near room temperature

Energy Technology Data Exchange (ETDEWEB)

Cagliero, Stefano; Khan, Mohammad Mizanur Rahman [Torino Universita, ' NIS' Centre of Excellence, Dip. Chimica Generale e Chimica Organica, and CNISM UdR, Turin (Italy); Torino Universita, ' NIS' Centre of Excellence, Dip. Fisica Sperimentale, and CNISM UdR, Turin (Italy); Agostino, Angelo [Torino Universita, ' NIS' Centre of Excellence, Dip. Chimica Generale e Chimica Organica, and CNISM UdR, Turin (Italy); Truccato, Marco [Torino Universita, ' NIS' Centre of Excellence, Dip. Fisica Sperimentale, and CNISM UdR, Turin (Italy); Orsini, Francesco; Marinone, Massimo; Poletti, Giulio [Universita degli Studi di Milano, Istituto di Fisiologia Generale e Chimica Biologica, Milan (Italy); CNR-INFM-S3 NRC, Modena (Italy); Lascialfari, Alessandro [Universita degli Studi di Milano, Istituto di Fisiologia Generale e Chimica Biologica, Milan (Italy); CNR-INFM-S3 NRC, Modena (Italy); Universita degli Studi di Pavia, INFM-CNR c/o Dipartimento di Fisica A. Volta, Pavia (Italy)

2009-05-15

We report new evidences for the thermodynamic instability of whisker crystals in the Bi-Sr-Ca-Cu-O (BSCCO) system. Annealing treatments at 90 C have been performed on two sets of samples, which were monitored by means of X-rays diffraction (XRD) and atomic force microscopy (AFM) measurements, respectively. Two main crystalline domains of Bi{sub 2}Sr{sub 2}CuCa{sub 2}O{sub 8+x} (Bi-2212) were identified in the samples by the XRD data, which underwent an evident crystalline segregation after about 60 hours. Very fast dynamics of the surface modifications was also described by the AFM monitoring. Two typologies of surface structures formed after about 3 annealing hours: continuous arrays of dome shaped bodies were observed along the edges of the whiskers, while in the central regions a dense texture of flat bodies was found. These modifications are described in terms of the formation of simple oxide clusters involving a degradation of the internal layers. (orig.)

Contribution of Titanium, Chromium and Carbon Buffer Interlayers to Bio-Tribological Properties of Multilayer Composites

Directory of Open Access Journals (Sweden)

Major Ł

2016-09-01

Full Text Available Research studies on bio-tribological protective coatings of titanium, chromium and carbon based have been performed. Thin films were fabricated by hybrid PLD technique (PLD supported by magnetron sputtering. Coatings consisted of two parts; the inner part (first from the substrate in each case was formed by titanium or chromium/titanium nitride or chromium nitride (Ti/TiN or Cr/Cr2N. The outer part was formed by pure DLC or multilayer DLC/Ti or Cr. No delamination was found at the interface. Titanium or chromium metallic layer was deposited as a first layer directly on the metallic substrate to avoid delamination. All individual layers were built of columnar nano-crystallites. Mechanisms of the mechanical wear of analyzed systems were presented, focusing on the cracking propagation in ball-on-disc tests using an 1 N and 5 N applied loads for 5 000 cycles. Complex microstructure analysis of presented nano-multilayer coatings, before and after mechanical tests, were performed by means of transmission electron microscopy (TEM. The highest stress concentration during mechanical uploading was moved through the multilayer coating by breaking only one layer at the time. The microstructure characterization revealed that cracking propagating in the outer part of the coating was stopped at the interface. In the case of the inner part of the coating Ti/TiN; Cr/Cr2N, ceramic layers showed brittle cracking, while metallic (Ti or Cr ones deformed plastically. Fabricated coatings were subjected under the analysis in the biomechanical system optimized to test for the direct contact with a human whole blood. The study considered physiological conditions mainly related to the temperature and humidity and the frequency of cyclic deformation of the artificial vessel into which the tested sample was introduced.

Correlation of Critical Temperatures and Electrical Properties in Titanium Films

Science.gov (United States)

Gandini, C.; Lacquaniti, V.; Monticone, E.; Portesi, C.; Rajteri, M.; Rastello, M. L.; Pasca, E.; Ventura, G.

Recently transition-edge sensors (TES) have obtained an increasing interest as light detectors due to their high energy resolution and broadband response. Titanium (Ti), with transition temperature up to 0.5 K, is among the suitable materials for TES application. In this work we investigate Ti films obtained from two materials of different purity deposited by e-gun on silicon nitride. Films with different thickness and deposition substrate temperature have been measured. Critical temperatures, electrical resistivities and structural properties obtained from x-ray are related to each other.

Plasma nitriding of steels

CERN Document Server

Aghajani, Hossein

2017-01-01

This book focuses on the effect of plasma nitriding on the properties of steels. Parameters of different grades of steels are considered, such as structural and constructional steels, stainless steels and tools steels. The reader will find within the text an introduction to nitriding treatment, the basis of plasma and its roll in nitriding. The authors also address the advantages and disadvantages of plasma nitriding in comparison with other nitriding methods. .

Pulsed 1064 nm Nd-YAG Laser Deposition of Titanium on Silicon in a Nitrogen Environment

Directory of Open Access Journals (Sweden)

Wilson Garcia

1999-12-01

Full Text Available Pulsed laser deposition (PLD technique was demonstrated for the deposition of titanium nitride (TiN thin films on Si (100 substrates. A 1064 nm pulsed Nd-YAG laser is focused on a titanium (99.5% target in a nitrogen environment to generate the atomic flux needed for the film deposition. Spectroscopic analysis of the plasma emission indicates the presence of atomic titanium and nitrogen, which are the precursors of TiN. Images of the films grown at different laser pulse energies show an increase in the number and size of deposited droplets and clusters with increasing laser pulse energy. A decrease in cluster and droplet size is also observed, with an increase in substrate temperature. EDS data show an increase in the titanium peak relative to the silicon as the ambient nitrogen pressure is decreased. An increase in deposition time was found to result in large clusters and irregularly shaped structures on the substrate. Post-deposition annealing of the samples enhanced the crystallinity of the film.

Electroluminescence of Zn{sub 2}GeO{sub 4}:Mn through SiC whisker electric field enhancement

Energy Technology Data Exchange (ETDEWEB)

Wagstaff, Brandon, E-mail: wagstabj@mcmaster.ca [McMaster University, Department of Engineering Physics, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L8 (Canada); Kitai, Adrian, E-mail: kitaia@mcmaster.ca [McMaster University, Department of Engineering Physics, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L8 (Canada); McMaster University, Department of Materials Science and Engineering, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L8 (Canada)

2015-11-15

Alternating current (AC) electroluminescence of thin film oxide phosphors is well known. However in this work electroluminescence of bulk oxide powder phosphors is achieved. A new type of AC Electroluminescent (ACEL) device has been created and developed by integrating SiC whiskers into a phosphor matrix composed of manganese-activated zinc germanate (Zn{sub 2}GeO{sub 4}:Mn{sup 2+}). The conductive SiC whiskers enhance the average electric field in specific regions of the phosphor such that localized breakdown of the phosphor occurs, thus emitting green light. This field enhancement allows light emission to occur in thick film oxide powder phosphors and is notably the first time that bright and reasonably efficient electroluminescence of zinc germanate has been observed without using expensive thin film deposition techniques. Light emission has been achieved in thick pressed pellets using surface-deposited electrodes and the brightness-voltage characteristics of light emission are shown to be consistent with field emission of carriers from the embedded whiskers. - Highlights: • A new electroluminescent phosphor, Zn{sub 2}GeO{sub 4}Mn{sup 2+}+SiC whiskers, is proposed. • A procedure is described to fabricate a solid sample of this composite material. • Under an AC voltage, green light is emitted only in samples containing the SiC whiskers. • A brightness of 25 Cd/m{sup 2} and efficiency of 0.25 Lm/W is observed 9.6×10{sup 6} V/m. • This is notably the first time that ACEL has been observed in bulk Zn{sub 2}GeO{sub 4}Mn{sup 2+}.

Physical and Chemical Properties of TiOxNy Prepared by Low-Temperature Oxidation of Ultrathin Metal Nitride Directly Deposited on SiO2

Institute of Scientific and Technical Information of China (English)

HAN Yue-Ping; HAN Yan

2009-01-01

Physical and chemical properties of titanium oxynitride (TiOxNy) formed by low-temperature oxidation of titanium nitride (TIN) layer are investigated for advanced metal-oxide--semiconductor (MOS) gate dielectric application.TiOx Ny exhibits polycrystalline properties after the standard thermal process for MOS device fabrication,showing the preferred orientation at [200].Superior electrical properties of TiOxNy can be maintained before and after the annealing,probably due to the nitrogen incorporation in the oxide bulk and at the interface.Naturally formed transition layer between TiOxNy and SiO2 is also confirmed.

Development and evaluation of two PVD-coated β-titanium orthodontic archwires for fluoride-induced corrosion protection.

Science.gov (United States)

Krishnan, Vinod; Krishnan, Anand; Remya, R; Ravikumar, K K; Nair, S Asha; Shibli, S M A; Varma, H K; Sukumaran, K; Kumar, K Jyothindra

2011-04-01

The present research was aimed at developing surface coatings on β titanium orthodontic archwires capable of protection against fluoride-induced corrosion. Cathodic arc physical vapor deposition PVD (CA-PVD) and magnetron sputtering were utilized to deposit thin films of titanium aluminium nitride (TiAlN) and tungsten carbide/carbon (WC/C) coatings on β titanium orthodontic archwires. Uncoated and coated specimens were immersed in a high fluoride ion concentration mouth rinse, following a specially designed cycle simulating daily use. All specimens thus obtained were subjected to critical evaluation of parameters such as electrochemical corrosion behaviour, surface analysis, mechanical testing, microstructure, element release, and toxicology. The results confirm previous research that β titanium archwires undergo a degradation process when in contact with fluoride mouth rinses. The study confirmed the superior nature of the TiAlN coating, evident as many fewer changes in properties after fluoride treatment when compared with the WC/C coating. Thus, coating with TiAlN is recommended in order to reduce the corrosive effects of fluorides on β titanium orthodontic archwires. Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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.

Effect of boron additions and processing on microstructure and mechanical properties of a titanium alloy Ti–6.5Al–3.3Mo–0.3Si

Energy Technology Data Exchange (ETDEWEB)

Imayev, V.M., E-mail: vimayev@mail.ru; Gaisin, R.A.; Imayev, R.M.

2015-08-12

The effects of boron additions in an amount of 0.1–2 wt%, thermomechanical processing and heat treatment on microstructure and mechanical properties of a two-phase titanium alloy Ti–6.5Al–3.3Mo–0.3Si alloy have been investigated. Depending on the boron amount, the materials under study were divided into two groups: (1) boron modified alloys containing ~0.1 wt% of boron and (2) discontinuously reinforced metal matrix Ti–TiB based composites containing 1.5–2 wt% of boron. Boron additions led to formation of TiB whiskers, which were predominantly located along boundaries of prior β-grains and α-colonies resulting in refined as-cast microstructure. Multiple 3D forging at T=650–700 °C applied for the boron modified alloys resulted in formation of ultrafine-grained microstructure and intensive breaking of TiB whiskers. Tensile properties of the Ti–6.5Al–3.3Mo–0.3Si–0.2 wt% B alloy after multiple 3D forging followed by β-heat treatment were found to be appreciably higher than those of the alloy free of boron after the same processing route that was ascribed to better controlling the β-grain size during β heat treatment. The composite materials were subjected to multiple isothermal 2D forging at T=950 °C that provided effective alignment of TiB whiskers while retaining their high aspect ratio. The hot forged composites demonstrated appreciably higher strength, creep resistance in comparison with those of the base alloy without drastic reduction in ductility. The effect of TiB whiskers orientation and morphology on the tensile properties of the composite materials is discussed.

Ion nitriding of aluminium

International Nuclear Information System (INIS)

Fitz, T.

2002-09-01

The present study is devoted to the investigation of the mechanism of aluminium nitriding by a technique that employs implantation of low-energy nitrogen ions and diffusional transport of atoms. The nitriding of aluminium is investigated, because this is a method for surface modification of aluminium and has a potential for application in a broad spectrum of fields such as automobile, marine, aviation, space technologies, etc. However, at present nitriding of aluminium does not find any large scale industrial application, due to problems in the formation of stoichiometric aluminium nitride layers with a sufficient thickness and good quality. For the purposes of this study, ion nitriding is chosen, as an ion beam method with the advantage of good and independent control over the process parameters, which thus can be related uniquely to the physical properties of the resulting layers. Moreover, ion nitriding has a close similarity to plasma nitriding and plasma immersion ion implantation, which are methods with a potential for industrial application. (orig.)

Sr{sub 1.98}Eu{sub 0.02}SiO{sub 4} luminescence whisker based on vapor-phase deposition: Facile synthesis, uniform morphology and enhanced luminescence properties

Energy Technology Data Exchange (ETDEWEB)

Xu, Jian, E-mail: xujian@stu.xmu.edu.cn [Department of Materials Science and Engineering, Xiamen University, Xiamen 361005 (China); Hassan, Dhia A. [Department of Materials Science and Engineering, Xiamen University, Xiamen 361005 (China); Department of Chemistry, College of Education for Pure Science, University of Basrah, 61004 (Iraq); Zeng, Renjie; Peng, Dongliang [Department of Materials Science and Engineering, Xiamen University, Xiamen 361005 (China); Fujian Key Lab of Advanced Special Material, Xiamen University, Xiamen 361005 (China); Key Laboratory of High Performance Ceramic Fibers, Ministry of Education, Xiamen 361005 (China)

2015-11-15

Highlights: • For the first time, it is possible to obtain Sr{sub 1.98}Eu{sub 0.02}SiO{sub 4} whisker. • The whiskers are smooth and uniform with L/D ratio over 50. • Durability and thermal stability of the whisker are enhanced. - Abstract: A high performance strontium silicate phosphor has been successfully synthesized though a facile vapor-phase deposition method. The product consists of single crystal whiskers which are smooth and uniform, and with a sectional equivalent diameter of around 5 μm; the aspect ratio is over 50 and no agglomeration can be observed. X-ray diffraction result confirmed that the crystal structure of the whisker was α’-Sr{sub 2}SiO{sub 4}. The exact chemical composition was Sr{sub 1.98}Eu{sub 0.02}SiO{sub 4} which was analyzed by energy dispersive spectrometer and inductively coupled plasma-mass spectrometer. The whisker shows broad green emission with peak at 523 nm ranging from 470 to 600 nm (excited at 370 nm). Compared with traditional Sr{sub 2}SiO{sub 4}:Eu phosphor, durability (at 85% humidity and 85 °C) and thermal stability of the whisker are obviously improved. Moreover, growth mechanism of the Sr{sub 1.98}Eu{sub 0.02}SiO{sub 4} whiskers is Vapor–Liquid–Solid. On a macro-scale, the product is still powder which makes it suitable for the current packaging process of WLEDs.

Whisker and Hillock formation on Sn, Sn-Cu and Sn-Pb electrodeposits

International Nuclear Information System (INIS)

Boettinger, W.J.; Johnson, C.E.; Bendersky, L.A.; Moon, K.-W.; Williams, M.E.; Stafford, G.R.

2005-01-01

High purity bright Sn, Sn-Cu and Sn-Pb layers, 3, 7 and 16 μm thick were electrodeposited on phosphor bronze cantilever beams in a rotating disk apparatus. Beam deflection measurements within 15 min of plating proved that all electrodeposits had in-plane compressive stress. In several days, the surfaces of the Sn-Cu deposits, which have the highest compressive stress, develop 50 μm contorted hillocks and 200 μm whiskers, pure Sn deposits develop 20 μm compact conical hillocks, and Sn-Pb deposits, which have the lowest compressive stress, remain unchanged. The differences between the initial compressive stresses for each alloy and pure Sn is due to the rapid precipitation of Cu 6 Sn 5 or Pb particles, respectively, within supersaturated Sn grains produced by electrodeposition. Over longer time, analysis of beam deflection measurements indicates that the compressive stress is augmented by the formation of Cu 6 Sn 5 on the bronze/Sn interface, while creep of the electrodeposit tends to decrease the compressive stress. Uniform creep occurs for Sn-Pb because it has an equi-axed grain structure. Localized creep in the form of hillocks and whiskers occurs for Sn and Sn-Cu because both have columnar structures. Compact hillocks form for the Sn deposits because the columnar grain boundaries are mobile. Contorted hillocks and whiskers form for the Sn-Cu deposits because the columnar grain boundary motion is impeded

Two-Dimensional Titanium Carbide (MXene) as Surface-Enhanced Raman Scattering Substrate

Energy Technology Data Exchange (ETDEWEB)

Sarycheva, Asia [Drexel Univ., Philadelphia, PA (United States); Makaryan, Taron [Drexel Univ., Philadelphia, PA (United States); Maleski, Kathleen [Drexel Univ., Philadelphia, PA (United States); Satheeshkumar, Elumalai [National Cheng Kung Univ., Tainan (Taiwan); National Institute of Technology-Trichy, Tamil Nadu (India); Melikyan, Armen [Russian-Armenian (Slavonic) State Univ., Yerevan (Armenia); Minassian, Hayk [A. Alikhanian National Science Lab., Yerevan (Armenia); Yoshimura, Masahiro [National Cheng Kung Univ., Tainan (Taiwan); Gogotsi, Yury G. [Drexel Univ., Philadelphia, PA (United States)

2017-08-22

Here, noble metal (gold or silver) nanoparticles or patterned films are typically used as substrates for surface-enhanced Raman spectroscopy (SERS). Two-dimensional (2D) carbides and nitrides (MXenes) exhibit unique electronic and optical properties, including metallic conductivity and plasmon resonance in the visible or near-infrared range, making them promising candidates for a wide variety of applications. Herein, we show that 2D titanium carbide, Ti₃C₂T_x, enhances Raman signal from organic dyes on a substrate and in solution. As a proof of concept, MXene SERS substrates were manufactured by spray-coating and used to detect several common dyes, with calculated enhancement factors reaching ~10⁶. Titanium carbide MXene demonstrates SERS effect in aqueous colloidal solutions, suggesting the potential for biomedical or environmental applications, where MXene can selectively enhance positively charged molecules.

Coating of the orthopaedic titanium alloys with sol-gel derived hydroxyapatite

International Nuclear Information System (INIS)

Milev, A.; Green, D.; Chai, C.S.; Ben-Nissan, B.

1999-01-01

Hydroxyapatite (HAp) is known to be both biocompatible and bioactive material, however, due to its poor mechanical properties and design limitations is not suitable for applying as a load bearing implant. This could be overcome by using appropriate metallic substrates covered with HAp, derived via different techniques. These coatings allow improved adhesion strength of the load bearing substrate to the bone, resulting in shorter healing periods as well as predictable behaviour of the implant for longer periods of time. There are different techniques of producing HAp appropriate for coating purposes. Due to the small particle size of the grains derived, sol-gel route is preferable where lower sintering temperatures are of primary importance. For better adhesion between substrate and hydroxyapatite coating, the surface of titanium substrate, in this study, was converted to titanium nitride and/or oxynitride. Sintering temperatures of 900 deg C have been used for producing crystalline HAp coatings. The control of sol-gel solutions and the analysis of the coatings were carried out using XRD, SEM and DTA techniques. Results obtained indicate high quality HAp coatings can be produced on titanium substrates especially with complex shapes that benefits over the other coating methods

Reactive Spark Plasma Sintering (SPS) of Nitride Reinforced Titanium Alloy Composites (Postprint)

Science.gov (United States)

2014-08-15

other industrial applications [21–25]. Titanium is widely used in the medical field to replace heart valves , joints, and bones for dental prosthetics due...their wear and fatigue resistance, hard coatings for dental implants and dental surgery tools, tribological orthopedic devices, gears, valves , pumps...their inherent brittleness and inferior fracture toughness [6,10–13]. In contrast, metal matrix composites (MMCs) reinforced with hard precipitates

Studies of the process of an unsteady formation of hard nitride coatings in an arc plasma flow

International Nuclear Information System (INIS)

Zake, M.

1996-01-01

The kinetic studies of an unsteady formation of hard ZrN and TiN coatings on the surface of metallic (Zr, Ti) samples in an Ar-N plasma flow are carried out. The obtained result is that at the initial stage of an unsteady heating of titanium samples nitrogen atoms penetrate into metal lattice and form interstitial compounds of hard nitrogen solutions in α-phase of Ti. This process is followed by a growth of thin surface layers of titanium nitrides with subsequent changes of surface radiance of exposed samples. Unsteady formation of ZrN is a similar two-stage process which includes the ZrN film growth and formation of a α-hard solution with subsequent changes of total normal emissivity of the surface. (author). 1 ref., 1 fig

Irradiation induced creep in whiskers of NaCl

International Nuclear Information System (INIS)

Khan, J.A.A.

1977-09-01

Whiskers of NaCl have been grown and irradiated under flexion by X-rays (approximately 2x10 7 R/h) at room temperature and the residual curvature measured. Complete recovery of the initial form of the whisker within an hour's annealing at 400 0 C proves clearly that the observed deformation (creep) is due to the presence of dislocation loops. The choice of NaCl extremely simplifies the experiment and its interpretation since X-rays create point defects one by one. Moreover, this mode of irradiation, at room temperature, produces a very simple situation: perfect interstitial dislocation loops and immobile point defects which are little influenced by the applied stress. The flexion leads to a stress system which hardly differs from an uniaxial stress. One can study separately the preferential nucleation of dislocation loops and their differential growth by carrying out an irradiation under stress followed by an irradiation without stress and vice versa. It is shown that the induced creep is mostly due to the preferential nucleation of dislocation loops and is little affected by the differential growth of these loops. The nucleation period of the loops is very short: a dose of approximately 10 -5 d.p.a. is largely sufficient for the quasi completion of dislocation loops in a crystal having an impurity concentration of approximately 10 -3 [fr

Magnetic whiskers of p-aminobenzoic acid and their use for preparation of filled and microchannel silicone rubbers

International Nuclear Information System (INIS)

Semenov, V. V.; Loginova, V. V.; Zolotareva, N. V.; Razov, E. N.; Kotomina, V. E.; Kruglov, A. V.

2016-01-01

A thin cobalt layer has been formed on the surface of p-aminobenzoic acid whiskers by chemical vapor deposition (CVD). The metallized crystals have been oriented in liquid polydimethylsiloxane rubber by applying a dc magnetic field. After vulcanization, the filler has been removed by processing in an alcohol solution of trifluoroacetic acid. The cobalt deposition on the surface of the organic compound and the properties of metallized whiskers are investigated by optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM).

Magnetic whiskers of p-aminobenzoic acid and their use for preparation of filled and microchannel silicone rubbers

Energy Technology Data Exchange (ETDEWEB)

Semenov, V. V., E-mail: vvsemenov@iomc.ras.ru; Loginova, V. V.; Zolotareva, N. V. [Russian Academy of Sciences, Razuvaev Institute of Organometallic Chemistry (Russian Federation); Razov, E. N. [Lobachevsky Nizhny Novgorod State University (Russian Federation); Kotomina, V. E.; Kruglov, A. V. [Lobachevsky Nizhny Novgorod State University, Physical‒Technical Research Institute (Russian Federation)

2016-07-15

A thin cobalt layer has been formed on the surface of p-aminobenzoic acid whiskers by chemical vapor deposition (CVD). The metallized crystals have been oriented in liquid polydimethylsiloxane rubber by applying a dc magnetic field. After vulcanization, the filler has been removed by processing in an alcohol solution of trifluoroacetic acid. The cobalt deposition on the surface of the organic compound and the properties of metallized whiskers are investigated by optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM).

Work Function Tuning in Sub-20nm Titanium Nitride (TiN) Metal Gate: Mechanism and Engineering

KAUST Repository

Hasan, Mehdi

2011-07-01

Scaling of transistors (the building blocks of modern information age) provides faster computation at the expense of excessive power dissipation. Thus to address these challenges, high-k/metal gate stack has been introduced in commercially available microprocessors from 2007. Since then titanium nitride (TiN) metal gate’s work function (Wf) tunability with its thickness (thickness increases, work function increases) is a well known phenomenon. Many hypotheses have been made over the years which include but not limited to: trap charge and metal gate nucleation, nitrogen concentration, microstructure agglomeration and global stress, metal oxide formation, and interfacial oxide thickness. However, clear contradictions exist in these assumptions. Also, nearly all these reports skipped a comprehensive approach to explain this complex paradigm. Therefore, in this work we first show a comprehensive physical investigation using transmission electron microcopy/electron energy loss spectroscopy (TEM/EELS), x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS) to show replacement of oxygen by nitrogen in the metal/dielectric interface, formation of TiONx, reduction of Ti/N concentration and grain size increment happen with TiN thickness increment and thus may increase the work function. Then, using these finding, we experimentally show 100meV of work function modulation in 10nm TiN Metal-oxide-semiconductor capacitor by using low temperature oxygen annealing. A low thermal budget flow (replicating gate-last) shows similar work function boost up. Also, a work function modulation of 250meV has been possible using oxygen annealing and applying no thermal budget. On the other hand, etch-back of TiN layer can decrease the work function. Thus this study quantifies role of various factors in TiN work function tuning; it also reproduces the thickness varied TiN work function modulation in single thickness TiN thus reducing the

Helical patterns of magnetization and magnetic charge density in iron whiskers

Science.gov (United States)

Templeton, Terry L.; Hanham, Scott D.; Arrott, Anthony S.

2018-05-01

Studies with the (1 1 1) axis along the long axis of an iron whisker, 40 years ago, showed two phenomena that have remained unexplained: 1) In low fields, there are six peaks in the ac susceptibility, separated by 0.2 mT; 2) Bitter patterns showed striped domain patterns. Multipole columns of magnetic charge density distort to form helical patterns of the magnetization, accounting for the peaks in the susceptibility from the propagation of edge solitons along the intersections of the six sides of a (1 1 1) whisker. The stripes follow the helices. We report micromagnetic simulations in cylinders with various geometries for the cross-sections from rectangular, to hexagonal, to circular, with wide ranges of sizes and lengths, and different anisotropies, including (0 0 1) whiskers and the hypothetical case of no anisotropy. The helical patterns have been there in previous studies, but overlooked. The surface swirls and body helices are connected, but have their own individual behaviors. The magnetization patterns are more easily understood when viewed observing the scalar divergences of the magnetization as isosurfaces of magnetic charge density. The plus and minus charge densities form columns that interact with unlike charges attracting, but not annihilating as they are paid for by a decrease in exchange energy. Just as they start to form the helix, the columns are multipoles. If one could stretch the columns, the self-energy of the charges in a column would be diminished while making the attractive interactions of the unlike charges larger. The columns elongate by becoming helical. The visualization of 3-D magnetic charge distributions aids in the understanding of magnetization in soft magnetic materials.

Piriform cortical glutamatergic and GABAergic neurons express coordinated plasticity for whisker-induced odor recall.

Science.gov (United States)

Liu, Yahui; Gao, Zilong; Chen, Changfeng; Wen, Bo; Huang, Li; Ge, Rongjing; Zhao, Shidi; Fan, Ruichen; Feng, Jing; Lu, Wei; Wang, Liping; Wang, Jin-Hui

2017-11-10

Neural plasticity occurs in learning and memory. Coordinated plasticity at glutamatergic and GABAergic neurons during memory formation remains elusive, which we investigate in a mouse model of associative learning by cellular imaging and electrophysiology. Paired odor and whisker stimulations lead to whisker-induced olfaction response. In mice that express this cross-modal memory, the neurons in the piriform cortex are recruited to encode newly acquired whisker signal alongside innate odor signal, and their response patterns to these associated signals are different. There are emerged synaptic innervations from barrel cortical neurons to piriform cortical neurons from these mice. These results indicate the recruitment of associative memory cells in the piriform cortex after associative memory. In terms of the structural and functional plasticity at these associative memory cells in the piriform cortex, glutamatergic neurons and synapses are upregulated, GABAergic neurons and synapses are downregulated as well as their mutual innervations are refined in the coordinated manner. Therefore, the associated activations of sensory cortices triggered by their input signals induce the formation of their mutual synapse innervations, the recruitment of associative memory cells and the coordinated plasticity between the GABAergic and glutamatergic neurons, which work for associative memory cells to encode cross-modal associated signals in their integration, associative storage and distinguishable retrieval.

Nitride stabilized core/shell nanoparticles

Science.gov (United States)

Kuttiyiel, Kurian Abraham; Sasaki, Kotaro; Adzic, Radoslav R.

2018-01-30

Nitride stabilized metal nanoparticles and methods for their manufacture are disclosed. In one embodiment the metal nanoparticles have a continuous and nonporous noble metal shell with a nitride-stabilized non-noble metal core. The nitride-stabilized core provides a stabilizing effect under high oxidizing conditions suppressing the noble metal dissolution during potential cycling. The nitride stabilized nanoparticles may be fabricated by a process in which a core is coated with a shell layer that encapsulates the entire core. Introduction of nitrogen into the core by annealing produces metal nitride(s) that are less susceptible to dissolution during potential cycling under high oxidizing conditions.

Application of cylinder symmetry to iron and titanium oxidation by oxygen or hydrogen-water vapour mixes

International Nuclear Information System (INIS)

Raynaud, Pierre

1980-01-01

This research thesis addresses the study of the oxidation reaction in the case of corrosion of iron by oxygen, hydrogen sulphide or hydrogen-water vapour mixes, and in the case of oxidation of titanium and of titanium nitride by hydrogen-water vapour mixes. It first addresses the corrosion of iron by oxygen with an experiment performed in cylinder symmetry: description of operational conditions, discussion of kinetic curves, development of a law of generation of multiple layers in cylinder symmetry, analytical exploitation of experimental results. The second part addresses the oxidation of iron by hydrogen-water vapour mixes: experimental conditions, influence of temperature on kinetics, micrographic study (oxide morphology, coating morphology, interpretation of differences with the case of plane symmetry), discussion of the influence of cylinder symmetry on oxidation kinetics. The third part addresses the oxidation of titanium by hydrogen-water vapour mixes: global kinetic evolution, reaction products and micrographic examination, morphology and texture studies, discussion of the oxidation mechanism and of cylinder symmetry [fr

Ceramic material suitable for repair of a space vehicle component in a microgravity and vacuum environment, method of making same, and method of repairing a space vehicle component

Science.gov (United States)

Riedell, James A. (Inventor); Easler, Timothy E. (Inventor)

2009-01-01

A precursor of a ceramic adhesive suitable for use in a vacuum, thermal, and microgravity environment. The precursor of the ceramic adhesive includes a silicon-based, preceramic polymer and at least one ceramic powder selected from the group consisting of aluminum oxide, aluminum nitride, boron carbide, boron oxide, boron nitride, hafnium boride, hafnium carbide, hafnium oxide, lithium aluminate, molybdenum silicide, niobium carbide, niobium nitride, silicon boride, silicon carbide, silicon oxide, silicon nitride, tin oxide, tantalum boride, tantalum carbide, tantalum oxide, tantalum nitride, titanium boride, titanium carbide, titanium oxide, titanium nitride, yttrium oxide, zirconium diboride, zirconium carbide, zirconium oxide, and zirconium silicate. Methods of forming the ceramic adhesive and of repairing a substrate in a vacuum and microgravity environment are also disclosed, as is a substrate repaired with the ceramic adhesive.

Fabrication of vanadium nitride by carbothermal nitridation reaction

International Nuclear Information System (INIS)

Wang Xitang; Wang Zhuofu; Zhang Baoguo; Deng Chengji

2005-01-01

Vanadium nitride is produced from V 2 O 5 by carbon-thermal reduction and nitridation. When the sintered temperature is above 1273 K, VN can be formed, and the nitrogen content of the products increased with the firing temperature raised, and then is the largest when the sintered temperature is 1573 K. The C/V 2 O 5 mass ratio of the green samples is the other key factor affecting on the nitrogen contents of the products. The nitrogen content of the products reaches the most when the C/V 2 O 5 mass ratio is 0.33, which is the theoretical ratio of the carbothermal nitridation of V 2 O 5 . (orig.)

Plasma-spray synthesis and characterization of ti-based nitride and oxide nanogranules

Energy Technology Data Exchange (ETDEWEB)

Antipas, Georgios S.E., E-mail: gantipas@metal.ntua.gr [School of Mining Engineering and Metallurgy, National Technical University of Athens, Athens (Greece)

2014-09-15

The synthesis of nanosized Ti-based nanogranules via plasma spraying is reported. The synthesis route involved use of both nitrogen and oxygen gases with varying results. In the case of nitrogen, a mixture of titanium nitrides were produced, yielding both the Ti2N and the sub-stoichiometric TiN0.61 compounds. In the case of oxygen, both the stoichiometric rutile and TiO ceramic phases were indexed. Based on EDS analysis, even fractional oxygen concentrations caused tungsten impurities which originated from the cathode electrode. The method yielded particle mass median sizes of the order of 15nm and the smallest particles detected were 5nm. (author)

[Corrosion resistance of casted titanium by compound treatments in the artificial saliva with different fluoride concentrations].

Science.gov (United States)

Wang, Xian-li; Guo, Tian-wen

2012-09-01

To study the corrosion resistance of casted titanium by plasma nitriding and TiN-coated compound treatments in the artificial saliva with different fluoride concentrations and to investigate whether compound treatments can increase the corrosion resistance of casted titanium. Potentiodynamic polarization technique was used to depict polarization curve and to measured the current density of corrosion (Icorr) and the electric potential of corrosion (Ecorr) of casted titanium (Group A) and casted titanium by compound treatments (Group B) in the artificial saliva with different fluoride concentrations. After electrochemical experiment, the microstructure was observed by scanning electron microscope (SEM). The Icorrs of Group A and B in the artificial saliva of different fluoride concentrations were (1530.23 ± 340.12), (2290.36 ± 320.10), (4130.52 ± 230.17) nA and (2.62 ± 0.64), (7.37 ± 3.59), (10.76 ± 6.05) nA, respectively. The Ecorrs were (-0.93 ± 0.10), (-0.89 ± 0.21), (-0.57 ± 0.09) V and (-0.21 ± 0.04), (-0.17 ± 0.03), (-0.22 ± 0.03) V, respectively.The Icorrs of Group B were significantly lower (P compound treatments can significantly increase the corrosion resistance of casted titanium.

Method for producing polycrystalline boron nitride

International Nuclear Information System (INIS)

Alexeevskii, V.P.; Bochko, A.V.; Dzhamarov, S.S.; Karpinos, D.M.; Karyuk, G.G.; Kolomiets, I.P.; Kurdyumov, A.V.; Pivovarov, M.S.; Frantsevich, I.N.; Yarosh, V.V.

1975-01-01

A mixture containing less than 50 percent of graphite-like boron nitride treated by a shock wave and highly defective wurtzite-like boron nitride obtained by a shock-wave method is compressed and heated at pressure and temperature values corresponding to the region of the phase diagram for boron nitride defined by the graphite-like compact modifications of boron nitride equilibrium line and the cubic wurtzite-like boron nitride equilibrium line. The resulting crystals of boron nitride exhibit a structure of wurtzite-like boron nitride or of both wurtzite-like and cubic boron nitride. The resulting material exhibits higher plasticity as compared with polycrystalline cubic boron nitride. Tools made of this compact polycrystalline material have a longer service life under impact loads in machining hardened steel and chilled iron. (U.S.)

Spontaneous growth of whiskers from an interlayer of Mo sub 2 C beneath a diamond particle deposited in a combustion-flame

Energy Technology Data Exchange (ETDEWEB)

Okada, Katsuyuki; Komatsu, Shojiro; Ishigaki, Takamasa; Matsumoto, Seiichiro; Moriyoshi, Yusuke (National Inst. for Research in Inorganic Materials, Tsukuba, Ibaraki (Japan))

1992-02-01

When diamond particles deposited on a molybdenum substrate in a C{sub 2}H{sub -}O{sub 2} combustion-flame were kept for one year in the ambient atmosphere at room temperature, spontaneous whisker growth from an interlayer of Mo{sub 2}C beneath the diamond particles took place. The whiskers were clarified by electron probe micro-analysis (EPMA) and transmission electron microscopy (TEM) in a polycrystal composed of MoO{sub 2}, MoOC, and Mo{sub 2}C. The growth mechanism of them is discussed from two different points of view as follows: One is that the oxidation of an interlayer of Mo{sub 2}C beneath a diamond particle effectively reduces the surface free energy between the interlayer and diamond particle; consequently, the whisker can grow by using a screw dislocation. The other is that the internal stress existing between a diamond particle and an Mo{sub 2}C interlayer provides a very reactive zone where the growth of whisker takes place through the oxidation of Mo{sub 2}C. (orig.).

Preparation of uranium nitride

International Nuclear Information System (INIS)

Potter, R.A.; Tennery, V.J.

1976-01-01

A process is described for preparing actinide-nitrides from massive actinide metal which is suitable for sintering into low density fuel shapes by partially hydriding the massive metal and simultaneously dehydriding and nitriding the dehydrided portion. The process is repeated until all of the massive metal is converted to a nitride

Ethanolic extract of Astragali radix and Salviae radix prohibits oxidative brain injury by psycho-emotional stress in whisker removal rat model.

Directory of Open Access Journals (Sweden)

Hyeong-Geug Kim

Full Text Available Myelophil, an ethanolic extract of Astragali Radix and Salviae Radix, has been clinically used to treat chronic fatigue and stress related disorders in South Korea. In this study, we investigated the protective effects of Myelophil on a whisker removal-induced psycho-emotional stress model. SD rats were subjected to whisker removal after oral administration of Myelophil or ascorbic acid for consecutive 4 days. Whisker removal considerably increased total reactive oxygen species in serum levels as well as cerebral cortex and hippocampal regions in brain tissues. Lipidperoxidation levels were also increased in the cerebral cortex, hippocampus regions, and brain tissue injuries as shown in histopathology and immunohistochemistry. However, Myelophil significantly ameliorated these alterations, and depletion of glutathione contents in both cerebral cortex and hippocampus regions respectively. Serum levels of corticosterone and adrenaline were notably altered after whisker removal stress, whereas these abnormalities were significantly normalized by pre-treatment with Myelophil. The NF-κB was notably activated in both cerebral cortex and hippocampus after whisker removal stress, while it was efficiently blocked by pre-treatment with Myelophil. Myelophil also significantly normalizes alterations of tumor necrosis factor-α, interleukin (IL-1β, IL-6 and interferon-γ in both gene expressions and protein levels. These results suggest that Myelophil has protective effects on brain damages in psycho-emotional stress, and the underlying mechanisms involve regulation of inflammatory proteins, especially NF-κB modulation.

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.

Zinc oxide crystal whiskers as a novel sorbent for solid-phase extraction of flavonoids.

Science.gov (United States)

Wang, Licheng; Shangguan, Yangnan; Hou, Xiudan; Jia, Yong; Liu, Shujuan; Sun, Yingxin; Guo, Yong

2017-08-15

As a novel solid-phase extraction material, zinc oxide crystal whiskers were used to extract flavonoid compounds and showed good extraction abilities. X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy and surface area/pore volume characterized the sorbent. The zinc oxide was packed into a solid-phase extraction micro-column and its extraction ability was evaluated by four model flavonoid compounds. The sample loading and elution parameters were optimized and the zinc oxide based analytical method for flavonoids was established. It showed that the method has wide linearities from 1 to 150μg/L and low limits of detection at 0.25μg/L. The relative standard deviations of a single column repeatability and column to column reproducibility were less than 6.8% and 10.6%. Several real samples were analyzed by the established method and satisfactory results were obtained. The interactions between flavonoids and zinc oxide were calculated and proved to be from the Van der Waals' forces between the 4p and 5d orbitals from zinc atom and the neighboring π orbitals from flavonoid phenyl groups. Moreover, the zinc oxide crystal whiskers showed good stability and could be reused more than 50 times under the operation conditions. This work proves that the zinc oxide crystal whiskers are a good candidate for flavonoids enrichment. Copyright © 2017. Published by Elsevier B.V.

Process for the production of metal nitride sintered bodies and resultant silicon nitride and aluminum nitride sintered bodies

Science.gov (United States)

Yajima, S.; Omori, M.; Hayashi, J.; Kayano, H.; Hamano, M.

1983-01-01

A process for the manufacture of metal nitride sintered bodies, in particular, a process in which a mixture of metal nitrite powders is shaped and heated together with a binding agent is described. Of the metal nitrides Si3N4 and AIN were used especially frequently because of their excellent properties at high temperatures. The goal is to produce a process for metal nitride sintered bodies with high strength, high corrosion resistance, thermal shock resistance, thermal shock resistance, and avoidance of previously known faults.

Strain gradient plasticity effects in whisker-reinforced metals

DEFF Research Database (Denmark)

Niordson, Christian Frithiof

2002-01-01

A metal reinforced by fibers in the micron range is studied using the strain gradient plasticity theory of Fleck and Hutchinson (2001). Cell-model analyzes are used to study the influence of the material length parameters numerically. Different higher order boundary conditions are considered...... at the fiber-matrix interface. The results are presented as overall stress-strain curves for the whisker-reinforced metal, and also contour plots of effective plastic strain are shown. The strain gradient plasticity theory predicts a significant stiffening effect when compared to conventional models...

Electrochemical migration, whisker formation, and corrosion behavior of printed circuit board under wet H2S environment

International Nuclear Information System (INIS)

Zou, Shiwen; Li, Xiaogang; Dong, Chaofang; Ding, Kangkang; Xiao, Kui

2013-01-01

Highlights: •The electrochemical migration, whisker formation, and corrosion behavior of PCB under wet H 2 S environment were observed and studied systematically. •The process of electrochemical migration of solder joints is explained. •The corrosion mechanism of PCB interconnectors induced by micro pores under wet H 2 S environment is discussed, and the corrosion reaction model is proposed. -- Abstract: Electrochemical migration, whisker formation, and corrosion behavior of printed circuit board (PCB) under wet H 2 S environment were analyzed by environment scanning electron microscope (ESEM), Energy dispersive X-ray spectroscopy (EDS) with mapping and element phase cluster (EPC) techniques, Raman Spectrum analysis and electrochemical impedance spectroscopy (EIS) technology. The results showed that nonuniform corrosion behavior occurred on PCB surfaces under 1 ppm wet H 2 S at 40 °C; whiskers formed on the inner sidewall of via-holes with a growth rate of 1.2 Å/s; numerous corrosion products migrated through the pore of plated gold layer, which broke off the protective layer. The corrosion rate was accelerated according to the big-cathode-small-anode model

Weldability with Process Parameters During Fiber Laser Welding of a Titanium Plate (I) - Effect of Type and Flow Rate of Shielding Gases on Weldability -

Energy Technology Data Exchange (ETDEWEB)

Kim, Jong Do; Kim, Ji Sung [Korea Maritime and Ocean Univ., Busan (Korea, Republic of)

2016-12-15

In this study, welding of pure titanium was carried out by using a continuous wave fiber laser with a maximum output of 6.3 kW. Because brittle regions form easily in titanium as a result of oxidation or nitriding, the weld must be protected from the atmosphere by using an appropriate shielding gas. Experiments were performed by changing the type and the flow rate of shielding gases to obtain the optimal shielding condition, and the weldability was then evaluated. The degree of oxidation and nitriding was distinguished by observing the color of beads, and weld microstructure was observed by using an optical microscope and a scanning electron microscope. The mechanical properties of the weld were examined by measuring hardness. When the weld was oxidized or nitrified, the bead color was gray or yellow, and the oxygen or nitrogen content in the bead surface and overall weld tended to be high, as a result of which the hardness of the weld was thrice that of the base metal. A sound silvery white bead was obtained by using Ar as the shielding gas.

Developing an Empirical Model for Estimating the Probability of Electrical Short Circuits from Tin Whiskers. Part 2

Science.gov (United States)

Courey, Karim J.; Asfour, Shihab S.; Onar, Arzu; Bayliss, Jon A.; Ludwig, Larry L.; Wright, Maria C.

2009-01-01

To comply with lead-free legislation, many manufacturers have converted from tin-lead to pure tin finishes of electronic components. However, pure tin finishes have a greater propensity to grow tin whiskers than tin-lead finishes. Since tin whiskers present an electrical short circuit hazard in electronic components, simulations have been developed to quantify the risk of said short circuits occurring. Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that had an unknown probability associated with it. Note however that due to contact resistance electrical shorts may not occur at lower voltage levels. In our first article we developed an empirical probability model for tin whisker shorting. In this paper, we develop a more comprehensive empirical model using a refined experiment with a larger sample size, in which we studied the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From the resulting data we estimated the probability distribution of an electrical short, as a function of voltage. In addition, the unexpected polycrystalline structure seen in the focused ion beam (FIB) cross section in the first experiment was confirmed in this experiment using transmission electron microscopy (TEM). The FIB was also used to cross section two card guides to facilitate the measurement of the grain size of each card guide's tin plating to determine its finish.

Hot pressing of uranium nitride and mixed uranium plutonium nitride

International Nuclear Information System (INIS)

Chang, J.Y.

1975-01-01

The hot pressing characteristics of uranium nitride and mixed uranium plutonium nitride were studied. The utilization of computer programs together with the experimental technique developed in the present study may serve as a useful purpose of prediction and fabrication of advanced reactor fuel and other high temperature ceramic materials for the future. The densification of nitrides follow closely with a plastic flow theory expressed as: d rho/ dt = A/T(t) (1-rho) [1/1-(1-rho)/sup 2/3/ + B1n (1-rho)] The coefficients, A and B, were obtained from experiment and computer curve fitting. (8 figures) (U.S.)

Whisker and Nose Tactile Sense Guide Rat Behavior in a Skilled Reaching Task

Directory of Open Access Journals (Sweden)

Pierantonio Parmiani

2018-02-01

Full Text Available Skilled reaching is a complex movement in which a forelimb is extended to grasp food for eating. Video-recordings analysis of control rats enables us to distinguish several components of skilled reaching: Orient, approaching the front wall of the reaching box and poking the nose into the slot to locate the food pellet; Transport, advancing the forelimb through the slot to reach-grasp the pellet; and Withdrawal of the grasped food to eat. Although food location and skilled reaching is guided by olfaction, the importance of whisker/nose tactile sense in rats suggests that this too could play a role in reaching behavior. To test this hypothesis, we studied skilled reaching in rats trained in a single-pellet reaching task before and after bilateral whisker trimming and bilateral infraorbital nerve (ION severing. During the task, bilaterally trimmed rats showed impaired Orient with respect to controls. Specifically, they detected the presence of the wall by hitting it with their nose (rather than their whiskers, and then located the slot through repetitive nose touches. The number of nose touches preceding poking was significantly higher in comparison to controls. On the other hand, macrovibrissae trimming resulted in no change in reaching/grasping or withdrawal components of skilled reaching. Bilaterally ION-severed rats, displayed a marked change in the structure of their skilled reaching. With respect to controls, in ION-severed rats: (a approaches to the front wall were significantly reduced at 3–5 and 6–8 days; (b nose pokes were significantly reduced at 3–5 days, and the slot was only located after many repetitive nose touches; (c the reaching-grasping-retracting movement never appeared at 3–5 days; (d explorative paw movements, equal to zero in controls, reached significance at 9–11 days; and (e the restored reaching-grasping-retracting sequence was globally slower than in controls, but the success rate was the same. These findings

3D printed biomimetic whisker-based sensor with co-planar capacitive sensing

NARCIS (Netherlands)

Delamare, John; Sanders, Remco G.P.; Krijnen, Gijsbertus J.M.

2016-01-01

This paper describes the development of a whisker sensor for tactile purposes and which is fabricated by 3D printing. Read-out consists of a capacitive measurement of a co-planar capacitance which is affected by a dielectric that is driven into the electric field of the capacitance. The current

Metal Nitrides for Plasmonic Applications

DEFF Research Database (Denmark)

Naik, Gururaj V.; Schroeder, Jeremy; Guler, Urcan

2012-01-01

Metal nitrides as alternatives to metals such as gold could offer many advantages when used as plasmonic material. We show that transition metal nitrides can replace metals providing equally good optical performance for many plasmonic applications.......Metal nitrides as alternatives to metals such as gold could offer many advantages when used as plasmonic material. We show that transition metal nitrides can replace metals providing equally good optical performance for many plasmonic applications....

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

Characteristics of Au/PZT/TiO2/Nitride/Si structure capacitors with ICP nitride treatments

International Nuclear Information System (INIS)

Min, Hyung Seob; Kim, Tae Ho; Jeon, Chang Bae; Lee, Jae Gab; Kim, Ji Young

2002-01-01

In this study, the characteristics of PZT/TiO 2 ferroelectric gate stack capacitors with Inductively Coupled Plasma (ICP) nitridation were investigated for field effect transistor (FET)-type Ferroelectric Random Access Memory (FeRAM) applications. If a high accumulation capacitance is to be had, the ICP nitridation time needs to be optimized. While a short ICP treatment time results in thermal oxide growth due to lack of nitrogen, a long nitridation time causes a nitride layer which is too thick. Au/PZT(200 nm)/TiO 2 (40 nm)/Nitride/Si (MeFINS) structure capacitors show a memory window (ΔV) of 1.6 V under ±3-V operation while Au/PZT(200 nm)/TiO 2 (40 nm)/Si (MeFIS) capacitors without nitride treatment exhibit a small memory window of 0.6 V. At the same time, the capacitance of the MeFINS device is almost twice that of the MeFIS capacitor. This result implies that the ICP nitride treatment suppresses the formation of a low dielectric constant interfacial SiO x layer and alleviates the series capacitance problem

Properties of minor actinide nitrides

International Nuclear Information System (INIS)

Takano, Masahide; Itoh, Akinori; Akabori, Mitsuo; Arai, Yasuo; Minato, Kazuo

2004-01-01

The present status of the research on properties of minor actinide nitrides for the development of an advanced nuclear fuel cycle based on nitride fuel and pyrochemical reprocessing is described. Some thermal stabilities of Am-based nitrides such as AmN and (Am, Zr)N were mainly investigated. Stabilization effect of ZrN was cleary confirmed for the vaporization and hydrolytic behaviors. New experimental equipments for measuring thermal properties of minor actinide nitrides were also introduced. (author)

Multifunctional zirconium nitride/copper multilayer coatings on medical grade 316L SS and titanium substrates for biomedical applications.

Science.gov (United States)

Kumar, D Dinesh; Kaliaraj, Gobi Saravanan

2018-01-01

Protecting from wear and corrosion of many medical devices in the biomedical field is an existing scientific challenge. Surface modification with multilayer ZrN/Cu coating was deposited on medical grade stainless steel (SS) and titanium substrates to enhance their surface properties. Structural results revealed that the ZrN/Cu coatings are highly crystalline and uniform microstructure on both the substrates. Dry and wet tribological measurements of the coated titanium substrate exhibit enhanced wear resistance and low friction coefficient due to the improved microstructure. Similarly, the corrosion resistance was exceptionally improved on titanium substrates, resulting from the high inertness of coating to the SBF electrolyte solution. Antibacterial activity and epifluorescence results signify the effective killing of pathogens by means of ion release killing as well as contact killing mechanisms. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ion irradiation effects on the matrix phase of SiCf/SiC composites prepared by the whisker growing assisted CVI process

International Nuclear Information System (INIS)

Park, Kyeong Hwan; Park, Ji Yeon; Kang, Suk Min; Kim, Weon Ju; Jung, Choong Hwan; Ryu, Woo Seog

2005-01-01

SiC f /SiC composites are one of promising candidates for structural material of the next generation energy system such as GFR and fusion reactors. A number of fabrication methods have been studied for obtaining an outstanding SiC f /SiC composite with a high density, high crystallinity and purity. SiC f /SiC composites consisted of whisker-reinforced matrix have a great potential at the viewpoint both of the fabrication process and the mechanical properties. SiC whiskers formed between SiC fibers improve the densification of SiC matrix during CVI process. In addition, the reinforced whiskers would be likely to enhance the mechanical properties of matrix and SiC f /SiC composite. While there has been significant developmental work on manufacturing the SiC f /SiC composite by the whisker growing assisted CVI process, detailed understanding of what effects the complex in the operating conditions combined with realistic materials property data is not adequately understood. Especially, its irradiation effects are even less clear and not well understood. A method of charged-particle irradiation is the most important R and D topics for simulating the core conditions of the advanced nuclear systems. Many studies on radiation effects of SiC and SiC f /SiC composites using a method of ion irradiation have in progress for R and D of the advanced nuclear systems. In this present work, changes of the mechanical property of SiC whisker-reinforced matrix in SiC f /SiC composite were evaluated by means of the depth sensing indentation method before and after chargedparticle irradiation

Temperature induced complementary switching in titanium oxide resistive random access memory

Energy Technology Data Exchange (ETDEWEB)

Panda, D., E-mail: dpanda@nist.edu [Department of Electronics Engineering, National Institute of Science and Technology, Berhampur, Odisha 761008 (India); Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Simanjuntak, F. M.; Tseng, T.-Y. [Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, Hsinchu 30010, Taiwan (China)

2016-07-15

On the way towards high memory density and computer performance, a considerable development in energy efficiency represents the foremost aspiration in future information technology. Complementary resistive switch consists of two antiserial resistive switching memory (RRAM) elements and allows for the construction of large passive crossbar arrays by solving the sneak path problem in combination with a drastic reduction of the power consumption. Here we present a titanium oxide based complementary RRAM (CRRAM) device with Pt top and TiN bottom electrode. A subsequent post metal annealing at 400°C induces CRRAM. Forming voltage of 4.3 V is required for this device to initiate switching process. The same device also exhibiting bipolar switching at lower compliance current, Ic <50 μA. The CRRAM device have high reliabilities. Formation of intermediate titanium oxi-nitride layer is confirmed from the cross-sectional HRTEM analysis. The origin of complementary switching mechanism have been discussed with AES, HRTEM analysis and schematic diagram. This paper provides valuable data along with analysis on the origin of CRRAM for the application in nanoscale devices.

The role of titanium aluminide in n-gallium nitride ohmic contact technology

Science.gov (United States)

Pelto, Christopher M.

Ohmic contacts are essential to the realization of efficient and affordable nitride-based electronic and optoelectronic devices. Currently, the most successful ohmic contact schemes to n-GaN are based on the Al/Ti bilayer structure, although the mechanism responsible for the low resistance in these contacts is not sufficiently understood. In this work, the intermetallic TiAl3 has been employed both as a model ohmic contact system to help understand the essential features of the Al/Ti standard contact, as well as a thermally stable oxidation cap for the bilayer structure. A quaternary isotherm of the Al-Ti-Ga-N system was calculated at 600°C, which showed that a sufficient phase topology was present to apply the exchange mechanism to the TiAl 3/GaN couple. The exchange mechanism rationalized the selection of the TiAl3 intermetallic by predicting that an Al-rich AlGaN layer will form at the metal/semiconductor interface. As part of the investigation of these novel contact systems, a thorough characterization was undertaken on both a standard Al/Ti and Au/Ni/Al/Ti contact to n-GaN in which the essential processing parameters and metallurgical properties were identified. The TiAl 3 contact was found to exhibit inferior electrical behavior compared to the Al/Ti bilayer, requiring significantly higher annealing temperatures to achieve comparable specific contact resistance. It is conjectured that this is due to the early formation of a TiN layer at the metal/semiconductor interface of the bilayer contact, even though both contacts are suspected to form the Al-rich nitride layer at higher temperature. As an oxidation cap, the TiAl3 metallization was found to provide much improved performance characteristics compared to the four-layer Au/Al/Ni/Ti standard. The TiAl 3/Al/Ti contact proved to achieve optimal performance at a much lower temperature than the standard, and furthermore showed complete insensitivity to the oxidation content of the annealing ambient. Reaction

Effects of Adaptation on Discrimination of Whisker Deflection Velocity and Angular Direction in a Model of the Barrel Cortex

Directory of Open Access Journals (Sweden)

Mainak J. Patel

2018-06-01

Full Text Available Two important stimulus features represented within the rodent barrel cortex are velocity and angular direction of whisker deflection. Each cortical barrel receives information from thalamocortical (TC cells that relay information from a single whisker, and TC input is decoded by barrel regular-spiking (RS cells through a feedforward inhibitory architecture (with inhibition delivered by cortical fast-spiking or FS cells. TC cells encode deflection velocity through population synchrony, while deflection direction is encoded through the distribution of spike counts across the TC population. Barrel RS cells encode both deflection direction and velocity with spike rate, and are divided into functional domains by direction preference. Following repetitive whisker stimulation, system adaptation causes a weakening of synaptic inputs to RS cells and diminishes RS cell spike responses, though evidence suggests that stimulus discrimination may improve following adaptation. In this work, I construct a model of the TC, FS, and RS cells comprising a single barrel system—the model incorporates realistic synaptic connectivity and dynamics and simulates both angular direction (through the spatial pattern of TC activation and velocity (through synchrony of the TC population spikes of a deflection of the primary whisker, and I use the model to examine direction and velocity selectivity of barrel RS cells before and after adaptation. I find that velocity and direction selectivity of individual RS cells (measured over multiple trials sharpens following adaptation, but stimulus discrimination using a simple linear classifier by the RS population response during a single trial (a more biologically meaningful measure than single cell discrimination over multiple trials exhibits strikingly different behavior—velocity discrimination is similar both before and after adaptation, while direction classification improves substantially following adaptation. This is the

Rat whisker movement after facial nerve lesion: Evidence for autonomic contraction of skeletal muscle.

NARCIS (Netherlands)

Heaton, J.T.; Sheu, S.H.; Hohman, M.H.; Knox, C.J.; Weinberg, J.S.; Kleiss, I.J.; Hadlock, T.A.

2014-01-01

Vibrissal whisking is often employed to track facial nerve regeneration in rats; however, we have observed similar degrees of whisking recovery after facial nerve transection with or without repair. We hypothesized that the source of non-facial nerve-mediated whisker movement after chronic

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...

Electron Cloud in Steel Beam Pipe vs Titanium Nitride Coated and Amorphous Carbon Coated Beam Pipes in Fermilab's Main Injector

Energy Technology Data Exchange (ETDEWEB)

Backfish, Michael

2013-04-01

This paper documents the use of four retarding field analyzers (RFAs) to measure electron cloud signals created in Fermilab’s Main Injector during 120 GeV operations. The first data set was taken from September 11, 2009 to July 4, 2010. This data set is used to compare two different types of beam pipe that were installed in the accelerator. Two RFAs were installed in a normal steel beam pipe like the rest of the Main Injector while another two were installed in a one meter section of beam pipe that was coated on the inside with titanium nitride (TiN). A second data run started on August 23, 2010 and ended on January 10, 2011 when Main Injector beam intensities were reduced thus eliminating the electron cloud. This second run uses the same RFA setup but the TiN coated beam pipe was replaced by a one meter section coated with amorphous carbon (aC). This section of beam pipe was provided by CERN in an effort to better understand how an aC coating will perform over time in an accelerator. The research consists of three basic parts: (a) continuously monitoring the conditioning of the three different types of beam pipe over both time and absorbed electrons (b) measurement of the characteristics of the surrounding magnetic fields in the Main Injector in order to better relate actual data observed in the Main Injector with that of simulations (c) measurement of the energy spectrum of the electron cloud signals using retarding field analyzers in all three types of beam pipe.

Analysis of the collar-whisker structure of temperate lactococcal bacteriophage TP901-1

DEFF Research Database (Denmark)

Vegge, Christina Skovgaard; Neve, Horst; Brøndsted, Lone

2006-01-01

Proteins homologous to the protein NPS (neck passage structure) are widespread among lactococcal phages. We investigated the hypothesis that NPS is involved in the infection of phage TP901-1 by analysis of an NPS mutant. NPS was determined to form a collar-whisker complex but was shown to be none...

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.

Pulsed TEA CO2 Laser Irradiation of Titanium in Nitrogen and Carbon Dioxide Gases

Science.gov (United States)

Ciganovic, J.; Matavulj, P.; Trtica, M.; Stasic, J.; Savovic, J.; Zivkovic, S.; Momcilovic, M.

2017-12-01

Surface changes created by interaction of transversely excited atmospheric carbon dioxide (TEA CO2) laser with titanium target/implant in nitrogen and carbon dioxide gas were studied. TEA CO2 laser operated at 10.6 μm, pulse length of 100 ns and fluence of ˜17 J/cm2 which was sufficient for inducing surface modifications. Induced changes depend on the gas used. In both gases the grain structure was produced (central irradiated zone) but its forms were diverse, (N2: irregular shape; CO2: hill-like forms). Hydrodynamic features at peripheral zone, like resolidified droplets, were recorded only in CO2 gas. Elemental analysis of the titanium target surface indicated that under a nitrogen atmosphere surface nitridation occurred. In addition, irradiation in both gases was followed by appearance of plasma in front of the target. The existence of plasma indicates relatively high temperatures created above the target surface offering a sterilizing effect.

Architecture for coated conductors

Science.gov (United States)

Foltyn, Stephen R.; Arendt, Paul N.; Wang, Haiyan; Stan, Liliana

2010-06-01

Articles are provided including a base substrate having a layer of an oriented cubic oxide material with a rock-salt-like structure layer thereon, and, a layer of epitaxial titanium nitride upon the layer of an oriented cubic oxide material having a rock-salt-like structure. Such articles can further include thin films of high temperature superconductive oxides such as YBCO upon the layer of epitaxial titanium nitride or upon a intermediate buffer layer upon the layer of epitaxial titanium nitride.

Nitriding of high speed steel

International Nuclear Information System (INIS)

Doyle, E.D.; Pagon, A.M.; Hubbard, P.; Dowey, S.J.; Pilkington, A.; McCulloch, D.G.; Latham, K.; DuPlessis, J.

2010-01-01

Current practice when nitriding HSS cutting tools is to avoid embrittlement of the cutting edge by limiting the depth of the diffusion zone. This is accomplished by reducing the nitriding time and temperature and eliminating any compound layer formation. However, in many applications there is an argument for generating a compound layer with beneficial tribological properties. In this investigation results are presented of a metallographic, XRD and XPS analysis of nitrided surface layers generated using active screen plasma nitriding and reactive vapour deposition using cathodic arc. These results are discussed in the context of built up edge formation observed while machining inside a scanning electron microscope. (author)

Whiskers growth and self-healing in Ti-based metallic glasses during ion irradiation

Science.gov (United States)

Zhang, Kun; Hu, Zheng; Zhao, Ziqiang; Wei, Bingchen; Li, Yansen; Wei, Yuhang

2018-04-01

Ti-based metallic glasses were subjected to a 20 MeV Cl4+ ion radiation under liquid-nitrogen cooling. Their responses, as well as effects of the electronic excitation and nucleus-nucleus collision were evaluated. The collision cascade during irradiation typically changes the structure by increasing the liquid-like zone/cluster, or the content of the free volume. However, along the ion incident depth, the structure change is inhomogeneous. Numerous whiskers appear and aggregate on the side of the irradiation surface, which are several micrometers away from the edge. This corresponds with the maximum collision depth obtained by the Monte Carlo simulation, where nuclear loss plays a dominant role. Moreover, the liquid-like zone continually forms, which add to the whiskers growth and subsequent self-healing. Results suggest that the irradiation-induced local shear stress combines with the well-localized liquid-like zone results in the observed phenomena. This study demonstrates that metallic glasses have high morphological instability under ion irradiation, which assets can pave new paths for their further applications.

Solvothermal synthesis: a new route for preparing nitrides

CERN Document Server

Demazeau, G; Denis, A; Largeteau, A

2002-01-01

Solvothermal synthesis appears to be an interesting route for preparing nitrides such as gallium nitride and aluminium nitride, using ammonia as solvent. A nitriding additive is used to perform the reaction and, in the case of gallium nitride, is encapsulated by melt gallium. The syntheses are performed in the temperature range 400-800 deg. C and in the pressure range 100-200 MPa. The synthesized powders are characterized by x-ray diffraction and scanning electron microscopy. Finely divided gallium nitride GaN and aluminium nitride AlN, both with wurtzite-type structure, can be obtained by this route.

Preparation of Polyaniline-Doped Fullerene Whiskers

Directory of Open Access Journals (Sweden)

Bingzhe Wang

2013-01-01

Full Text Available Fullerene C60 whiskers (FWs doped with polyaniline emeraldine base (PANI-EB were synthesized by mixing PANI-EB/N-methyl pyrrolidone (NMP colloid and FWs suspension based on the nature of the electron acceptor of C60 and electron donor of PANI-EB. Scanning electron microscopy (SEM, Fourier transform infrared (FT-IR, and ultraviolet-visible (UV-Vis spectra characterized the morphology and molecular structure of the FWs doped with PANI-EB. SEM observation showed that the smooth surface of FWs was changed to worm-like surface morphology after being doped with PANI-EB. The UV-Vis spectra suggested that charge-transfer (CT complex of C60 and PANI-EB was formed as PANI-EBδ+-C60δ-. PANI-EB-doped FWs might be useful as a new type of antibacterial and self-cleaning agent as well as multifunctional material to improve the human health and living environment.

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.

Preparation of aluminum nitride-silicon carbide nanocomposite powder by the nitridation of aluminum silicon carbide

NARCIS (Netherlands)

Itatani, K.; Tsukamoto, R.; Delsing, A.C.A.; Hintzen, H.T.J.M.; Okada, I.

2002-01-01

Aluminum nitride (AlN)-silicon carbide (SiC) nanocomposite powders were prepared by the nitridation of aluminum-silicon carbide (Al4SiC4) with the specific surface area of 15.5 m2·g-1. The powders nitrided at and above 1400°C for 3 h contained the 2H-phases which consisted of AlN-rich and SiC-rich

Poly(Butylene Terephthalate Based Composites Containing Alumina Whiskers: Influence of Filler Functionalization on Dielectric Properties

Directory of Open Access Journals (Sweden)

Pietro Russo

2014-01-01

Full Text Available Poly(butylene terephthalate (PBT is one of the most widely used semicrystalline thermoplastics polyester because of its superior thermal and mechanical properties, high dimensional stability and excellent processability. In this research PBT-based nanocomposites, including various amounts (up to 10 wt% of commercial alumina whiskers, have been prepared by using a Brabender internal chamber mixer and analysed in terms of morphological features and dielectric properties. Specific attention has been focused on the effect of the filler functionalization considering 3-glycidoxy propylmethoxysilane (GPS or 3-methacryloxypropyltrimethoxysilane (MPS as coupling agents. Tests, performed on compounds filled with neat and functionalized alumina whiskers, show a clear dependence of relative dielectric permittivity εr, invariance of dissipation factor (tgδ, and a sensible increase of volume electrical resistivity (ρv with the filler’s content and are encouraging for a future introduction of such composites in many electrical applications.

TIDES-ACS Trial: comparison of titanium-nitride-oxide coated bio-active-stent to the drug (everolimus)-eluting stent in acute coronary syndrome. Study design and objectives.

Science.gov (United States)

Colkesen, E B; Eefting, F D; Rensing, B J; Suttorp, M J; Ten Berg, J M; Karjalainen, P P; Van Der Heyden, J A

2015-02-01

Drug-eluting stents (DES), delivering antiproliferative drugs from a durable polymer, have shown to reduce in-stent restenosis after percutaneous coronary intervention (PCI) compared to bare-metal stents (BMS). However, they have been associated with a hypersensitivity reaction, delayed healing, and incomplete endothelialization, which may contribute to an increased risk of late stent thrombosis. Consequently, a prolonged duration of dual antiplatelet therapy (DAPT) is needed, with an increased risk of bleeding complication. A number of stent technologies are being developed in an attempt to modify late thrombotic events and DAPT duration. The Optimax™ stent is such a novel, next generation bioactive stent (BAS), in which a thicker layer of titanium-nitride-oxide coating is inserted over the stent struts. The rationale of this is to obtain more efficient and rapid vascular healing at the site of the stent implantation. The aim of TIDES-ACS Trial is to compare clinical outcome in patients presenting with ACS, treated with PCI using Optimax-BAS versus Synergy™-EES. Second objective is to explore whether the Optimax™-BAS use is superior compared with Synergy™-EES use with respect of hard end points (cardiac death, myocardial infarction [MI] and major bleeding). A prospective, randomized, multicenter trial (ClinicalTrials.gov Identifier: NCT02049229), will be conducted in interventional centres in Finland (six centres), France (five centres) and Holland (two centres), including a total of 1800 patients.

Growth of single-crystal W whiskers during humid H2/N2 reduction of Ni, Fe-Ni, and Co-Ni doped tungsten oxide

International Nuclear Information System (INIS)

Wang Shiliang; He Yuehui; Zou Jou; Wang Yong; Huang Han

2009-01-01

Numbers of W whiskers were obtained by reducing Ni, Ni-Fe, and Ni-Co doped tungsten oxide in a mixed atmosphere of humid H 2 and N 2 . The phases and morphologies of the reduction products were characterized by XRD and SEM. Intensive TEM and EDS analyses showed that the obtained whiskers were W single crystals which typical have alloyed particles (Ni-W, Fe-Ni, or Co-Ni-W) at the growth tips. The formed W whiskers were presumed to be induced by the alloyed particles. Our experimental results revealed that, during the reduction process of tungsten oxide, the pre-reduced Ni, Fe-Ni, or Co-Ni particles not only served as nucleation aids for the initial growth of W phase from W oxide but also played the roles of catalysts during the reductive decomposition of gaseous WO 2 (OH) 2 .

Microstructural characterization of an AISI-SAE 4140 steel without nitridation and nitrided

International Nuclear Information System (INIS)

Medina F, A.; Naquid G, C.

2000-01-01

It was micro structurally characterized an AISI-SAE 4140 steel before and after of nitridation through the nitridation process by plasma post-unloading microwaves through Optical microscopy (OM), Scanning electron microscopy (SEM) by means of secondary electrons and retrodispersed, X-ray diffraction (XRD), Energy dispersion spectra (EDS) and mapping of elements. (Author)

Precipitation of metal nitrides from chloride melts

International Nuclear Information System (INIS)

Slater, S.A.; Miller, W.E.; Willit, J.L.

1996-01-01

Precipitation of actinides, lanthanides, and fission products as nitrides from molten chloride melts is being investigated for use as a final cleanup step in treating radioactive salt wastes generated by electrometallurgical processing of spent nuclear fuel. The radioactive components (eg, fission products) need to be removed to reduce the volume of high-level waste that requires disposal. To extract the fission products from the salt, a nitride precipitation process is being developed. The salt waste is first contacted with a molten metal; after equilibrium is reached, a nitride is added to the metal phase. The insoluble nitrides can be recovered and converted to a borosilicate glass after air oxidation. For a bench-scale experimental setup, a crucible was designed to contact the salt and metal phases. Solubility tests were performed with candidate nitrides and metal nitrides for which there are no solubility data. Experiments were performed to assess feasibility of precipitation of metal nitrides from chloride melts

Optogenetic probing of nerve and muscle function after facial nerve lesion in the mouse whisker system

Science.gov (United States)

Bandi, Akhil; Vajtay, Thomas J.; Upadhyay, Aman; Yiantsos, S. Olga; Lee, Christian R.; Margolis, David J.

2018-02-01

Optogenetic modulation of neural circuits has opened new avenues into neuroscience research, allowing the control of cellular activity of genetically specified cell types. Optogenetics is still underdeveloped in the peripheral nervous system, yet there are many applications related to sensorimotor function, pain and nerve injury that would be of great benefit. We recently established a method for non-invasive, transdermal optogenetic stimulation of the facial muscles that control whisker movements in mice (Park et al., 2016, eLife, e14140)1. Here we present results comparing the effects of optogenetic stimulation of whisker movements in mice that express channelrhodopsin-2 (ChR2) selectively in either the facial motor nerve (ChAT-ChR2 mice) or muscle (Emx1-ChR2 or ACTA1-ChR2 mice). We tracked changes in nerve and muscle function before and up to 14 days after nerve transection. Optogenetic 460 nm transdermal stimulation of the distal cut nerve showed that nerve degeneration progresses rapidly over 24 hours. In contrast, the whisker movements evoked by optogenetic muscle stimulation were up-regulated after denervation, including increased maximum protraction amplitude, increased sensitivity to low-intensity stimuli, and more sustained muscle contractions (reduced adaptation). Our results indicate that peripheral optogenetic stimulation is a promising technique for probing the timecourse of functional changes of both nerve and muscle, and holds potential for restoring movement after paralysis induced by nerve damage or motoneuron degeneration.

Effective Duration of Gas Nitriding Process on AISI 316L for the Formation of a Desired Thickness of Surface Nitrided Layer

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Mahmoud Hassan R. S.

2014-07-01

Full Text Available High temperature gas nitriding performed on AISI 316L at the temperature of 1200°C. The microstructure of treated AISI 316L samples were observed to identify the formation of the microstructure of nitrided surface layer. The grain size of austenite tends to be enlarged when the nitriding time increases, but the austenite single phase structure is maintained even after the long-time solution nitriding. Using microhardness testing, the hardness values drop to the center of the samples. The increase in surface hardness is due to the high nitrogen concentration at or near the surface. At 245HV, the graph of the effective duration of nitriding process was plotted to achieve the maximum depth of nitrogen diffuse under the surface. Using Sigma Plot software best fit lines of the experimental result found and plotted to find out effective duration of nitriding equation as Y=1.9491(1-0.7947x, where Y is the thickness of nitrided layer below the surface and X is duration of nitriding process. Based on this equation, the duration of gas nitriding process can be estimated to produce desired thickness of nitrided layer.

Ionic implantation by plasma in titanium and stainless steels used in prosthesis and medical instruments

International Nuclear Information System (INIS)

Munoz C, A. E.

2008-01-01

A study of a process known as plasma immersion ion implantation (PIII) of nitrogen at low voltages (< 4 kV) into three kind of samples: 1) austenitic stainless AISI 316-L steel plates, 2) ferritic stainless AISI 434 steel-based dentistry drills and 3) commercially pure titanium (CPTi) disks. On the case of CPTi the study was conducted in nitrogen- oxygen calibrated mixtures: 90% N-10% O, 80% N-20% O, 70% N-30% O and in 99.5% pure oxygen and 99.9% pure nitrogen. The PIII process was carried out by using a direct current plasma source controlled both in voltage and current, a negative voltage pulse modulator, a stainless AISI 304 steel vacuum chamber and a rod of the same material, horizontally located in the upper region of the chamber, which plays the role of anode in the plasma discharge. The purpose of the nitriding is forming a relatively thick layer on the surface of the steel specimens in order to enhance their both microhardness and general corrosion performances, desirable in medical applications. This layer contains interstitial nitrogen atoms (∼24% at.) which gives place to a deformed lattice (expanded phase) of the steel. Vickers microhardness and potentiodynamic tests (the latter in agreement to the norm ASTM G-61-89) confirm an increase of microhardness up to three times and a decrease of general corrosion rate in one order of magnitude. The nitriding of de dentistry drills is aimed at inhibiting the pitting corrosion produced by the asepsis process which results in pit nucleations, their propagation and consequent fractures when being under cyclic stress (fatigue). Scanning electron microscope micrographs reveal the risks involved in surpassing the critical treatment simple temperature of 450 C as the PIII process itself induces pitting. On its part, cyclic (ASTM G-61) potentiodynamic tests indicate an excellent pitting corrosion resistance of the samples treated under 450 C. In turn, the treatment of CPTi was meant to develop oxidized and

Separation of zirconium--hafnium by nitride precipitation

International Nuclear Information System (INIS)

Anderson, R.N.; Parlee, N.A.

1977-01-01

A method is described for the separation of a light reactive metal (e.g., zirconium) from a heavy reactive metal (e.g., hafnium) by forming insoluble nitrides of the metals in a molten metal solvent (e.g., copper) inert to nitrogen and having a suitable density for the light metal nitride to form a separate phase in the upper portion of the solvent and for the heavy metal nitride to form a separate phase in the lower portion of the solvent. Nitriding is performed by maintaining a nitrogen-containing atmosphere over the bath. The light and heavy metals may be an oxide mixture and carbothermically reduced to metal form in the same bath used for nitriding. The nitrides are then separately removed and decomposed to form the desired separate metals. 16 claims, 1 figure

Nitride fuels irradiation performance data base

International Nuclear Information System (INIS)

Brozak, D.E.; Thomas, J.K.; Peddicord, K.L.

1987-01-01

An irradiation performance data base for nitride fuels has been developed from an extensive literature search and review that emphasized uranium nitride, but also included performance data for mixed nitrides [(U,Pu)N] and carbonitrides [(U,Pu)C,N] to increase the quantity and depth of pin data available. This work represents a very extensive effort to systematically collect and organize irradiation data for nitride-based fuels. The data base has many potential applications. First, it can facilitate parametric studies of nitride-based fuels to be performed using a wide range of pin designs and operating conditions. This should aid in the identification of important parameters and design requirements for multimegawatt and SP-100 fuel systems. Secondly, the data base can be used to evaluate fuel performance models. For detailed studies, it can serve as a guide to selecting a small group of pin specimens for extensive characterization. Finally, the data base will serve as an easily accessible and expandable source of irradiation performance information for nitride fuels

Simple process to fabricate nitride alloy powders

International Nuclear Information System (INIS)

Yang, Jae Ho; Kim, Dong-Joo; Kim, Keon Sik; Rhee, Young Woo; Oh, Jang-Soo; Kim, Jong Hun; Koo, Yang Hyun

2013-01-01

Uranium mono-nitride (UN) is considered as a fuel material [1] for accident-tolerant fuel to compensate for the loss of fissile fuel material caused by adopting a thickened cladding such as SiC composites. Uranium nitride powders can be fabricated by a carbothermic reduction of the oxide powders, or the nitriding of metal uranium. Among them, a direct nitriding process of metal is more attractive because it has advantages in the mass production of high-purity powders and the reusing of expensive 15 N 2 gas. However, since metal uranium is usually fabricated in the form of bulk ingots, it has a drawback in the fabrication of fine powders. The Korea Atomic Energy Research Institute (KAERI) has a centrifugal atomisation technique to fabricate uranium and uranium alloy powders. In this study, a simple reaction method was tested to fabricate nitride fuel powders directly from uranium metal alloy powders. Spherical powder and flake of uranium metal alloys were fabricated using a centrifugal atomisation method. The nitride powders were obtained by thermal treating the metal particles under nitrogen containing gas. The phase and morphology evolutions of powders were investigated during the nitriding process. A phase analysis of nitride powders was also part of the present work. KAERI has developed the centrifugal rotating disk atomisation process to fabricate spherical uranium metal alloy powders which are used as advanced fuel materials for research reactors. The rotating disk atomisation system involves the tasks of melting, atomising, and collecting. A nozzle in the bottom of melting crucible introduces melt at the center of a spinning disk. The centrifugal force carries the melt to the edge of the disk and throws the melt off the edge. Size and shape of droplets can be controlled by changing the nozzle size, the disk diameter and disk speed independently or simultaneously. By adjusting the processing parameters of the centrifugal atomiser, a spherical and flake shape

Microhardness and microplasticity of zirconium nitride

International Nuclear Information System (INIS)

Neshpor, V.S.; Eron'yan, M.A.; Petrov, A.N.; Kravchik, A.E.

1978-01-01

To experimentally check the concentration dependence of microhardness of 4 group nitrides, microhardness of zirconium nitride compact samples was measured. The samples were obtained either by bulk saturation of zirconium iodide plates or by chemical precipitation from gas. As nitrogen content decreased within the limits of homogeneity of zirconium nitride samples where the concentration of admixed oxygen was low, the microhardness grew from 1500+-100 kg/mm 2 for ZrNsub(1.0) to 27000+-100 kg/mm 2 for ZrNsub(0.78). Microplasticity of zirconium nitride (resistance to fracture) decreased, as the concentration of nitrogen vacancies was growing

Surface analysis in steel nitrides by using Moessbauer spectroscopy

International Nuclear Information System (INIS)

Figueiredo, R.S. de.

1991-07-01

The formation of iron nitride layer at low temperatures, 600-700 K, by Moessbauer spectroscopy is studied. These layers were obtained basically through two different processes: ion nitriding and ammonia gas nitriding. A preliminary study about post-discharge nitriding was made using discharge in hollow cathode as well as microwave excitation. The assembly of these chambers is also described. The analysis of the nitrided samples was done by CEMS and CXMS, aided by optical microscopy, and the CEMS and CXMS detectors were constructed by ourselves. We also made a brief study about these detectors, testing as acetone as the mixture 80% He+10% C H 4 as detection gases for the use of CEMS. The surface analysis of the samples showed that in the ammonia gas process nitriding the nitrided layer starts by the superficial formation of an iron nitride rich nitrogen. By thermal evolution this nitride promotes the diffusion of nitrogen and the formation of other more stable nitrides. (author)

Semiconducting cubic titanium nitride in the ${\mathrm{Th}}_3{{P}}_4$ structure

Energy Technology Data Exchange (ETDEWEB)

Bhadram, Venkata S.; Liu, Hanyu; Xu, Enshi; Li, Tianshu; Prakapenka, Vitali B.; Hrubiak, Rostislav; Lany, Stephan; Strobel, Timothy A.

2018-01-01

We report the discovery of a long-sought-after phase of titanium nitride with stoichiometry Ti 3 N 4 using diamond anvil cell experiments combined with in situ high-resolution x-ray diffraction and Raman spectroscopy techniques, supported by ab initio calculations. Ti 3 N 4 crystallizes in the cubic Th 3 P 4 structure [space group I ¯ 4 3 d (220)] from a mixture of TiN and N 2 above ≈ 75 GPa and ≈ 2400 K. The density ( ≈ 5.22 g/cc) and bulk modulus ( K 0 = 290 GPa) of cubic- Ti 3 N 4 ( c - Ti 3 N 4 ) at 1 atm, estimated from the pressure-volume equation of state, are comparable to rocksalt TiN. Ab initio calculations based on the GW approximation and using hybrid functionals indicate that c - Ti 3 N 4 is a semiconductor with a direct band gap between 0.8 and 0.9 eV, which is larger than the previously predicted values. The c - Ti 3 N 4 phase is not recoverable to ambient pressure due to dynamic instabilities, but recovery of Ti 3 N 4 in the defect rocksalt (or related) structure may be feasible.

Nitriding behavior of Ni and Ni-based binary alloys

Energy Technology Data Exchange (ETDEWEB)

Fonovic, Matej

2015-01-15

Gaseous nitriding is a prominent thermochemical surface treatment process which can improve various properties of metallic materials such as mechanical, tribological and/or corrosion properties. This process is predominantly performed by applying NH{sub 3}+H{sub 2} containing gas atmospheres serving as the nitrogen donating medium at temperatures between 673 K and 873 K (400 C and 600 C). NH{sub 3} decomposes at the surface of the metallic specimen and nitrogen diffuses into the surface adjacent region of the specimen whereas hydrogen remains in the gas atmosphere. One of the most important parameters characterizing a gaseous nitriding process is the so-called nitriding potential (r{sub N}) which determines the chemical potential of nitrogen provided by the gas phase. The nitriding potential is defined as r{sub N} = p{sub NH{sub 3}}/p{sub H{sub 2}{sup 3/2}} where p{sub NH{sub 3}} and p{sub H{sub 2}} are the partial pressures of the NH{sub 3} and H{sub 2} in the nitriding atmosphere. In contrast with nitriding of α-Fe where the nitriding potential is usually in the range between 0.01 and 1 atm{sup -1/2}, nitriding of Ni and Ni-based alloys requires employing nitriding potentials higher than 100 atm{sup -1/2} and even up to ∞ (nitriding in pure NH{sub 3} atmosphere). This behavior is compatible with decreased thermodynamic stability of the 3d-metal nitrides with increasing atomic number. Depending on the nitriding conditions (temperature, nitriding potential and treatment time), different phases are formed at the surface of the Ni-based alloys. By applying very high nitriding potential, formation of hexagonal Ni{sub 3}N at the surface of the specimen (known as external nitriding) leads to the development of a compound layer, which may improve tribological properties. Underneath the Ni{sub 3}N compound layer, two possibilities exist: (i) alloying element precipitation within the nitrided zone (known as internal nitriding) and/or (ii) development of metastable and

Tailoring the morphology and electrocatalytic properties of electrochemically formed Ag/TiO2 composite deposits on titanium surfaces

Directory of Open Access Journals (Sweden)

S. V. MENTUS

2007-12-01

Full Text Available Three different forms of Ag/TiO2 composite layers, which have whisker-, dot- and island-like distribution of silver were obtained on a mechanically polished titanium surface by adjusting the conditions of silver deposition from an aqueous AgNO3 solution. The deposit morphology was the result of both the program of electrode polarization and the template action of the simultaneously formed TiO2 layer. The catalytic activity of the composite layers toward the oxygen reduction reaction was studied in aqueous 0.1 M NaOH solutions and found to be a function of both the surface loading of silver and the type of silver distribution within the Ag/TiO2 composite layers. The reaction path of oxygen reduction on the composite layers was found to be always a 4e- one, characteristic otherwise of polycrystalline silver electrodes.

Alloy Effects on the Gas Nitriding Process

Science.gov (United States)

Yang, M.; Sisson, R. D.

2014-12-01

Alloy elements, such as Al, Cr, V, and Mo, have been used to improve the nitriding performance of steels. In the present work, plain carbon steel AISI 1045 and alloy steel AISI 4140 were selected to compare the nitriding effects of the alloying elements in AISI 4140. Fundamental analysis is carried out by using the "Lehrer-like" diagrams (alloy specific Lehrer diagram and nitriding potential versus nitrogen concentration diagram) and the compound layer growth model to simulate the gas nitriding process. With this method, the fundamental understanding for the alloy effect based on the thermodynamics and kinetics becomes possible. This new method paves the way for the development of new alloy for nitriding.

Ion nitridation - physical and technological aspects

International Nuclear Information System (INIS)

Elbern, A.W.

1980-01-01

Ion nitridation, is a technique which allows the formation of a controlled thickness of nitrides in the surface of the material, using this material as the cathode in a low pressure glow discharge, which presents many advantages over the conventional method. A brief review of the ion nitriding technique, the physical fenomena involved, and we discuss technological aspects of this method, are presented. (Author) [pt

Silicon nitride-fabrication, forming and properties

International Nuclear Information System (INIS)

Yehezkel, O.

1983-01-01

This article, which is a literature survey of the recent years, includes description of several methods for the formation of silicone nitride, and five methods of forming: Reaction-bonded silicon nitride, sintering, hot pressing, hot isostatic pressing and chemical vapour deposition. Herein are also included data about mechanical and physical properties of silicon nitride and the relationship between the forming method and the properties. (author)

Synthesis of reduced carbon nitride at the reduction by hydroquinone of water-soluble carbon nitride oxide (g-C{sub 3}N{sub 4})O

Energy Technology Data Exchange (ETDEWEB)

Kharlamov, Alexey [Frantsevich Institute for Problems of Materials Science of NASU, Krzhyzhanovsky St. 3, 03680 Kiev (Ukraine); Bondarenko, Marina, E-mail: mebondarenko@ukr.net [Frantsevich Institute for Problems of Materials Science of NASU, Krzhyzhanovsky St. 3, 03680 Kiev (Ukraine); Kharlamova, Ganna [Taras Shevchenko National University of Kiev, Volodymyrs' ka St. 64, 01601 Kiev (Ukraine); Fomenko, Veniamin [Frantsevich Institute for Problems of Materials Science of NASU, Krzhyzhanovsky St. 3, 03680 Kiev (Ukraine)

2016-09-15

For the first time at the reduction by hydroquinone of water-soluble carbon nitride oxide (g-C{sub 3}N{sub 4})O reduced carbon nitride (or reduced multi-layer azagraphene) is obtained. It is differed from usually synthesized carbon nitride by a significantly large (on 0.09 nm) interplanar distance is. At the same time, the chemical bonds between atoms in a heteroatomic plane of reduced carbon nitride correspond to the bonds in a synthesized g-C{sub 3}N{sub 4}. The samples of water-soluble carbon nitride oxide were synthesized under the special reactionary conditions of a pyrolysis of melamine and urea. We believe that reduced carbon nitride consists of weakly connected carbon-nitrogen monosheets (azagraphene sheets) as well as reduced (from graphene oxide) graphene contains weakly connected graphene sheets. - Graphical abstract: XRD pattern and schematic atomic model of one layer of reduced carbon nitride, carbon nitride oxide and synthesized carbon nitride. For the first time at the reduction by hydroquinone of the water-soluble carbon nitride oxide (g-C{sub 3}N{sub 4})O is obtained the reduced carbon nitride (or reduced multi-layer azagraphene). Display Omitted - Highlights: • First the reduced carbon nitride (RCN) at the reduction of the carbon nitride oxide was obtained. • Water-soluble carbon nitride oxide was reduced by hydroquinone. • The chemical bonds in a heteroatomic plane of RCN correspond to the bonds in a synthesized g-C{sub 3}N{sub 4}. • Reduced carbon nitride consists of poorly connected heteroatomic azagraphene layers.

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.

Self-propagating high-temperature synthesis of diamond-containing function-gradient materials with a ceramic matrix based on TiB2-TiN and Ti5Si3-TiN

International Nuclear Information System (INIS)

Levashov, E.A.; Akulinin, P.V.; Sorokin, M.N.; Sviridova, T.A.; Khosomi, S.; Okh'yanagi, M.; Koizumi, S.

2004-01-01

For the first time a study is made into specific features of phase- and structure formation in diamond-bearing functionally gradient materials (FGM) with a ceramic binder on the basis of titanium diboride and nitride TiB 2 -TiN as well as titanium silicide and nitride Ti 5 Si 3 -TiN. For a titanium diboride and nitride base binder the maximum residual strength of diamond grains is 24 N for a specimen with 12.5 vol. % of diamond and 29 N for a specimen with 25 vol. % of diamond in a charge layer when an initial strength of diamond grains is equal to 37 N. For a titanium silicide and nitride base binder the residual strength of diamond in synthesized products is 32.5 and 28.7 N for specimens with 12.5 and 25 vol. % of diamond respectively, the initial strength of diamond grains being the same. A positive effect is shown for a 5% additive of titanium hydride in a charge diamond-bearing layer on the preservation of diamond in a tita nium diboride and nitride binder. Optimal conditions are determined to provide the possibility of obtaining high-quality products with a high degree of preservation and strength of diamond grains [ru

Topotactic synthesis of vanadium nitride solid foams

International Nuclear Information System (INIS)

Oyama, S.T.; Kapoor, R.; Oyama, H.T.; Hofmann, D.J.; Matijevic, E.

1993-01-01

Vanadium nitride has been synthesized with a surface area of 120 m 2 g -1 by temperature programmed nitridation of a foam-like vanadium oxide (35 m 2 g -1 ), precipitated from vanadate solutions. The nitridation reaction was established to be topotactic and pseudomorphous by x-ray powder diffraction and scanning electron microscopy. The crystallographic relationship between the nitride and oxide was {200}//{001}. The effect of precursor geometry on the product size and shape was investigated by employing vanadium oxide solids of different morphologies

Microstructure and mechanical properties of silicon nitride structural ceramics of silicon nitride

International Nuclear Information System (INIS)

Strohaecker, T.R.; Nobrega, M.C.S.

1989-01-01

The utilization of direct evaluation technic of tenacity for fracturing by hardness impact in silicon nitride ceramics is described. The microstructure were analysied, by Scanning Electron Microscopy, equiped with a microanalysis acessory by X ray energy dispersion. The difference between the values of K IC measure for two silicon nitride ceramics is discussed, in function of the microstructures and the fracture surfaces of the samples studied. (C.G.C.) [pt

The prospect of uranium nitride (UN) and mixed nitride fuel (UN-PuN) for pressurized water reactor

International Nuclear Information System (INIS)

Syarifah, Ratna Dewi; Suud, Zaki

2015-01-01

Design study of small Pressurized Water Reactors (PWRs) core loaded with uranium nitride fuel (UN) and mixed nitride fuel (UN-PuN), Pa-231 as burnable poison, and Americium has been performed. Pa-231 known as actinide material, have large capture cross section and can be converted into fissile material that can be utilized to reduce excess reactivity. Americium is one of minor actinides with long half life. The objective of adding americium is to decrease nuclear spent fuel in the world. The neutronic analysis results show that mixed nitride fuel have k-inf greater than uranium nitride fuel. It is caused by the addition of Pu-239 in mixed nitride fuel. In fuel fraction analysis, for uranium nitride fuel, the optimum volume fractions are 45% fuel fraction, 10% cladding and 45% moderator. In case of UN-PuN fuel, the optimum volume fractions are 30% fuel fraction, 10% cladding and 60% coolant/ moderator. The addition of Pa-231 as burnable poison for UN fuel, enrichment U-235 5%, with Pa-231 1.6% has k-inf more than one and excess reactivity of 14.45%. And for mixed nitride fuel, the lowest value of reactivity swing is when enrichment (U-235+Pu) 8% with Pa-231 0.4%, the excess reactivity value 13,76%. The fuel pin analyze for the addition of Americium, the excess reactivity value is lower than before, because Americium absorb the neutron. For UN fuel, enrichment U-235 8%, Pa-231 1.6% and Am 0.5%, the excess reactivity is 4.86%. And for mixed nitride fuel, when enrichment (U-235+Pu) 13%, Pa-231 0.4% and Am 0.1%, the excess reactivity is 11.94%. For core configuration, it is better to use heterogeneous than homogeneous core configuration, because the radial power distribution is better

The prospect of uranium nitride (UN) and mixed nitride fuel (UN-PuN) for pressurized water reactor

Science.gov (United States)

Syarifah, Ratna Dewi; Suud, Zaki

2015-09-01

Design study of small Pressurized Water Reactors (PWRs) core loaded with uranium nitride fuel (UN) and mixed nitride fuel (UN-PuN), Pa-231 as burnable poison, and Americium has been performed. Pa-231 known as actinide material, have large capture cross section and can be converted into fissile material that can be utilized to reduce excess reactivity. Americium is one of minor actinides with long half life. The objective of adding americium is to decrease nuclear spent fuel in the world. The neutronic analysis results show that mixed nitride fuel have k-inf greater than uranium nitride fuel. It is caused by the addition of Pu-239 in mixed nitride fuel. In fuel fraction analysis, for uranium nitride fuel, the optimum volume fractions are 45% fuel fraction, 10% cladding and 45% moderator. In case of UN-PuN fuel, the optimum volume fractions are 30% fuel fraction, 10% cladding and 60% coolant/ moderator. The addition of Pa-231 as burnable poison for UN fuel, enrichment U-235 5%, with Pa-231 1.6% has k-inf more than one and excess reactivity of 14.45%. And for mixed nitride fuel, the lowest value of reactivity swing is when enrichment (U-235+Pu) 8% with Pa-231 0.4%, the excess reactivity value 13,76%. The fuel pin analyze for the addition of Americium, the excess reactivity value is lower than before, because Americium absorb the neutron. For UN fuel, enrichment U-235 8%, Pa-231 1.6% and Am 0.5%, the excess reactivity is 4.86%. And for mixed nitride fuel, when enrichment (U-235+Pu) 13%, Pa-231 0.4% and Am 0.1%, the excess reactivity is 11.94%. For core configuration, it is better to use heterogeneous than homogeneous core configuration, because the radial power distribution is better.

Humidity-dependent stability of amorphous germanium nitrides fabricated by plasma nitridation

International Nuclear Information System (INIS)

Kutsuki, Katsuhiro; Okamoto, Gaku; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji

2007-01-01

We have investigated the stability of amorphous germanium nitride (Ge 3 N 4 ) layers formed by plasma nitridation of Ge(100) surfaces using x-ray photoelectron spectroscopy and atomic force microscopy. We have found that humidity in the air accelerates the degradation of Ge 3 N 4 layers and that under 80% humidity condition, most of the Ge-N bonds convert to Ge-O bonds, producing a uniform GeO 2 layer, within 12 h even at room temperature. After this conversion of nitrides to oxides, the surface roughness drastically increased by forming GeO 2 islands on the surfaces. These findings indicate that although Ge 3 N 4 layers have superior thermal stability compared to the GeO 2 layers, Ge 3 N 4 reacts readily with hydroxyl groups and it is therefore essential to take the best care of the moisture in the fabrication of Ge-based devices with Ge 3 N 4 insulator or passivation layers

Fabrication of SiC Composites with Synergistic Toughening of Carbon Whisker and In Situ 3C-SiC Nanowire

Directory of Open Access Journals (Sweden)

Zhang Yunlong

2016-01-01

Full Text Available The SiC composites with synergistic toughening of carbon whisker and in situ 3C-SiC nanowire have been fabricated by hot press sinter technology and annealed treatment technology. Effect of annealed time on the morphology of SiC nanowires and mechanical properties of the Cw/SiC composites was surveyed in detail. The appropriate annealed time improved mechanical properties of the Cw/SiC composites. The synergistic effect of carbon whisker and SiC nanowire can improve the fracture toughness for Cw/SiC composites. The vapor-liquid-solid growth (VLS mechanism was proposed. TEM photo showed that 3C-SiC nanowire can be obtained with preferential growth plane ({111}, which corresponded to interplanar spacing about 0.25 nm.

Optical characterization of gallium nitride

NARCIS (Netherlands)

Kirilyuk, Victoria

2002-01-01

Group III-nitrides have been considered a promising system for semiconductor devices since a few decades, first for blue- and UV-light emitting diodes, later also for high-frequency/high-power applications. Due to the lack of native substrates, heteroepitaxially grown III-nitride layers are usually

Microstructure and mechanical properties of 2.5 vol. % TiBw/Ti6Al4V composites plates fabricated by hot-hydrostatic canned extrusion

Science.gov (United States)

Zhang, Wencong; Zhang, Lingjia; Feng, Yangju; Cui, Guorong; Chen, Wenzhen

2018-04-01

Plates of 2.5 vol. % TiB whisker-reinforced Ti6Al4V titanium matrix composites (TiBw/Ti64) with network structure were successfully fabricated by hot-hydrostatic extrusion with steel cup at 1100 °C. The dimensions of plates were about 150mm in length, 27mm in width and 2mm in thickness. After extrusion, the original equiaxed-network structure formed by TiB whiskers still existed, but was compressed in cross-section and stretched in longitudinal section and then the TiB whiskers were directional distribution along the extrusion direction. Furthermore, the mechanical properties results showed that the strength, hardness and ductility of the plates were significantly improved compared to as-sintered composites.

Electrophoretic deposition of hydroxyapatite-hexagonal boron nitride composite coatings on Ti substrate.

Science.gov (United States)

Göncü, Yapıncak; Geçgin, Merve; Bakan, Feray; Ay, Nuran

2017-10-01

In this study, commercial pure titanium samples were coated with nano hydroxyapatite-nano hexagonal boron nitride (nano HA-nano hBN) composite by electrophoretic deposition (EPD). The effect of process parameters (applied voltage, deposition time and solid concentration) on the coating morphology, thickness and the adhesion behavior were studied systematically and crack free nano hBN-nano HA composite coating production was achieved for developing bioactive coatings on titanium substrates for orthopedic applications. For the examination of structural and morphological characteristics of the coating surfaces, various complementary analysis methods were performed. For the structural characterization, XRD and Raman Spectroscopy were used while, Scanning Electron Microscopy (SEM) equipped with an energy dispersive spectrometer (EDS) and Transmission Electron Microscopy (TEM) techniques were carried out for revealing the morphological characterization. The results showed that nano HA-nano hBN were successfully deposited on Ti surface with uniform, crack-free coating by EPD. The amounts of hBN in suspension are considered to have no effect on coating thickness. By adding hBN into HA, the morphology of HA did not change and hBN has no significant effect on porous structure. These nanostructured surfaces are expected to be suitable for proliferation of cells and have high potential for bioactive materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Hydrogen diffusion between plasma-deposited silicon nitride-polyimide polymer interfaces

International Nuclear Information System (INIS)

Nguyen, S.V.; Kerbaugh, M.

1988-01-01

This paper reports a nuclear reaction analysis (NRA) for hydrogen technique used to analyze the hydrogen concentration near plasma enhanced chemical vapor deposition (PECVD) silicon nitride-polyimide interfaces at various nitride-deposition and polyimide-polymer-curing temperatures. The CF 4 + O 2 (8% O 2 ) plasma-etch-rate variation of PECVD silicon nitride films deposited on polyimide appeared to correlate well with the variation of hydrogen-depth profiles in the nitride films. The NRA data indicate that hydrogen-depth-profile fluctuation in the nitride films is due to hydrogen diffusion between the nitride-polyimide interfaces during deposition. Annealing treatment of polyimide films in a hydrogen atmosphere prior to the nitride film deposition tends to enhance the hydrogen-depth-profile uniformity in the nitride films, and thus substantially reduces or eliminates variation in the nitride plasma-etch rate

Nucleation of iron nitrides during gaseous nitriding of iron; the effect of a preoxidation treatment

DEFF Research Database (Denmark)

Friehling, Peter B.; Poulsen, Finn Willy; Somers, Marcel A.J.

2001-01-01

grains. On prolonged nitriding, immediate nucleation at the surface of iron grains becomes possible. Calculated incubation times for the nucleation of gamma'-Fe4N1-x during nitriding are generally longer than those observed experimentally in the present work. The incubation time is reduced dramatically...

RF plasma nitriding of severely deformed iron-based alloys

International Nuclear Information System (INIS)

Ferkel, H.; Glatzer, M.; Estrin, Y.; Valiev, R.Z.; Blawert, C.; Mordike, B.L.

2003-01-01

The effect of severe plastic deformation by cold high pressure torsion (HPT) on radio frequency (RF) plasma nitriding of pure iron, as well as St2K50 and X5CrNi1810 steels was investigated. Nitriding was carried out for 3 h in a nitrogen atmosphere at a pressure of 10 -5 bar and temperatures of 350 and 400 deg. C. Nitrided specimens were analysed by scanning electron microscopy (SEM), X-ray diffraction and micro hardness measurements. It was found that HPT enhances the effect of nitriding leading almost to doubling of the thickness of the nitrided layer for pure iron and the high alloyed steel. The largest increase in hardness was observed when HPT was combined with RF plasma nitriding at 350 deg. C. In the case of pure iron, the X-ray diffraction spectra showed the formation of ε and γ' nitrides in the compound layer, with a preferential formation of γ' at the expense of the α-phase at the higher nitriding temperature. The corresponding surface hardness was up to 950 HV0.01. While the HPT-processed St2K50 exhibits both nitride phases after nitriding at 350 deg. C, only the γ'-phase was observed after nitriding at 400 deg. C. A surface hardness of up to 1050 HV0.01 was measured for this steel. The high alloyed steel X5CrNi1810 exhibited the highest increase in surface hardness when HPT was combined with nitriding at 350 deg. C. The surface hardness of this steel was greater than 1400 HV0.025. The XRD analyses indicate the formation of the expanded austenite (S-phase) in the surface layer as a result of RF plasma nitriding. Furthermore, after HPT X5CrNi1810 was transformed completely into deformation martensite which did not transform back to austenite under thermochemical treatment. However, in the case of nitriding of the HPT-processed high alloyed steel at 400 deg. C, the formation of the S-phase was less pronounced. In view of the observed XRD peak broadening, the formation of nitrides, such as e.g. CrN, cannot be ruled out

Development of pseudocapacitive molybdenum oxide–nitride for electrochemical capacitors

Energy Technology Data Exchange (ETDEWEB)

Ting, Yen-Jui Bernie [Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario M5S 3E4 (Canada); Wu, Haoran [Department of Materials Science and Engineering, University of Toronto, Toronto, Ontario M5S 3E4 (Canada); Kherani, Nazir P. [Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario M5S 3E4 (Canada); Department of Materials Science and Engineering, University of Toronto, Toronto, Ontario M5S 3E4 (Canada); Lian, Keryn, E-mail: keryn.lian@utoronto.ca [Department of Materials Science and Engineering, University of Toronto, Toronto, Ontario M5S 3E4 (Canada)

2015-03-15

A thin film Mo oxide–nitride pseudocapacitive electrode was synthesized by electrodeposition of Mo oxide on Ti and a subsequent low-temperature (400 °C) thermal nitridation. Two nitridation environments, N{sub 2} and NH{sub 3}, were used and the results were compared. Surface analyses of these nitrided films showed partial conversion of Mo oxide to nitrides, with a lower conversion percentage being the film produced in N{sub 2}. However, the electrochemical analyses showed that the surface of the N{sub 2}-treated film had better pseudocapacitive behaviors and outperformed that nitrided in NH{sub 3}. Cycle life of the resultant N{sub 2}-treated Mo oxide–nitride was also much improved over Mo oxide. A two-electrode cell using Mo oxide–nitride electrodes was demonstrated and showed high rate performance. - Highlights: • Mo(O,N){sub x} was developed by electrodeposition and nitridation in N{sub 2} or NH{sub 3}. • N{sub 2} treated Mo(O,N){sub x} showed a capacitive performance superior to that treated by NH{sub 3}. • The promising electrochemical performance was due to the formation of γ-Mo{sub 2}N.

Effects of Hot-Hydrostatic Canned Extrusion on the Stock Utilization, Microstructure and Mechanical Properties of TiBw/TC4 Composites with Quasi-Continuous Network.

Science.gov (United States)

Feng, Yangju; Li, Bing; Cui, Guorong; Zhang, Wencong

2017-10-25

In-situ TiB whisker-reinforced Ti-6Al-4V (TC4) titanium matrix composites (TiBw/TC4) with quasi-continuous networks were successfully fabricated by vacuum hot-pressing sintering. The effects of the hot-hydrostatic canned extrusion on stock utilization, microstructure and mechanical properties of the TiBw/TC4 composites were investigated. It was satisfactory that the utilization of composites could be obviously improved by canned extrusion compared to that extruded without canned extrusion. The microstructure results showed that after canned extrusion the grain was refined and the TiB whiskers were distributed from a random array state to a state in which the whiskers were distributed along the extrusion direction. The properties testing results revealed that the tensile strength, the hardness and the ductility of the composites all significantly improved after extrusion due to the grain refinement and orientation of the TiB whisker caused by extrusion. Tensile fracture results showed that when the TiB whiskers were randomly distributed only part of them played a role in strengthening the matrix during the deformation process (as-sintered composites), while when the TiB whiskers were oriented all whiskers could strengthen the matrix during the tensile testing process (as-extruded composites).

New Routes to Lanthanide and Actinide Nitrides

Energy Technology Data Exchange (ETDEWEB)

Butt, D.P.; Jaques, B.J.; Osterberg, D.D. [Boise State University, 1910 University Dr., Boise, Idaho 83725-2075 (United States); Marx, B.M. [Concurrent Technologies Corporation, Johnstown, PA (United States); Callahan, P.G. [Carnegie Mellon University, Pittsburgh, PA (United States); Hamdy, A.S. [Central Metallurgical R and D Institute, Helwan, Cairo (Egypt)

2009-06-15

The future of nuclear energy in the U.S. and its expansion worldwide depends greatly on our ability to reduce the levels of high level waste to minimal levels, while maintaining proliferation resistance. Implicit in the so-called advanced fuel cycle is the need for higher levels of fuel burn-up and consequential use of complex nuclear fuels comprised of fissile materials such as Pu, Am, Np, and Cm. Advanced nitride fuels comprised ternary and quaternary mixtures of uranium and these actinides have been considered for applications in advanced power plants, but there remain many processing challenges as well as necessary qualification testing. In this presentation, the advantages and disadvantages of nitride fuels are discussed. Methods of synthesizing the raw materials and sintering of fuels are described including a discussion of novel, low cost routes to nitrides that have the potential for reducing the cost and footprint of a fuel processing plant. Phase pure nitrides were synthesized via four primary methods; reactive milling metal flakes in nitrogen at room temperature, directly nitriding metal flakes in a pure nitrogen atmosphere, hydriding metal flakes prior to nitridation, and carbo-thermically reducing the metal oxide and carbon mixture prior to nitridation. In the present study, the sintering of UN, DyN, and their solid solutions (U{sub x}, Dy{sub 1-x}) (x = 1 to 0.7) were also studied. (authors)

Importance of Fuel Cell Tests for Stability Assessment—Suitability of Titanium Diboride as an Alternative Support Material

Directory of Open Access Journals (Sweden)

Christina Roth

2014-06-01

Full Text Available Carbon corrosion is a severe issue limiting the long-term stability of carbon-supported catalysts, in particular in the highly dynamic conditions of automotive applications. (Doped oxides have been discussed as suitable alternatives to replace carbon, but often suffer from poor electron conductivity. That is why non-oxide ceramics, such as tungsten carbide and titanium nitride, have been discussed recently. Titanium diboride has also been proposed, due to its promising activity and stability in an aqueous electrochemical cell. In this work, Pt nanoparticles were deposited onto μm-sized TiB2 particles with improved grain size, manufactured into porous gas diffusion electrodes and tested in a realistic polymer electrolyte membrane (PEM fuel cell environment. In contrast to the model studies in an aqueous electrochemical cell, in the presence of oxygen and high potentials at the cathode side of a real fuel cell, TiB2 becomes rapidly oxidized as indicated by intensely colored regions in the membrane-electrode assembly (MEA. Moreover, already the electrode manufacturing process led to the formation of titanium oxides, as shown by X-ray diffraction measurements. This demonstrates that Cyclic Voltammetry (CV measurements in an aqueous electrochemical cell are not sufficient to prove stability of novel materials for fuel cell applications.

Stir zone microstructure of commercial purity titanium friction stir welded using pcBN tool

International Nuclear Information System (INIS)

Zhang Yu; Sato, Yutaka S.; Kokawa, Hiroyuki; Park, Seung Hwan C.; Hirano, Satoshi

2008-01-01

In the present study, friction stir welding was applied to commercial purity titanium using a polycrystalline cubic boron nitride tool, and microstructure and hardness in the weld were examined. Additionally, the microstructural evolution during friction stir welding was also discussed. The stir zone consisted of fine equiaxed α grains surrounded by serrate grain boundaries, which were produced through the β → α allotropic transformation during the cooling cycle of friction stir welding. The fine α grains caused higher hardness than that in the base material. A lath-shaped α grain structure containing Ti borides and tool debris was observed in the surface region of the stir zone, whose hardness was the highest in the weld

Plasma nitriding - an eco friendly surface hardening process

International Nuclear Information System (INIS)

Mukherjee, S.

2015-01-01

Surface hardening is a process of heating the metal such that the surface gets only hardened. This process is adopted for many components like gears, cams, and crankshafts, which desire high hardness on the outer surface with a softer core to withstand the shocks. So, to attain such properties processes like carburising, nitriding, flame hardening and induction hardening are employed. Amongst these processes nitriding is the most commonly used process by many industries. In nitriding process the steel material is heated to a temperature of around 550 C and then exposed to atomic nitrogen. This atomic nitrogen reacts with iron and other alloying elements and forms nitrides, which are very hard in nature. By this process both wear resistance and hardness of the product can be increased. The atomic nitrogen required for this process can be obtained using ammonia gas (gas nitriding), cyanide based salt bath (liquid nitriding) and plasma medium (plasma nitriding). However, plasma nitriding has recently received considerable industrial interest owing to its characteristic of faster nitrogen penetration, short treatment time, low process temperature, minimal distortion, low energy use and easier control of layer formation compared with conventional techniques such as gas and liquid nitriding. This process can be used for all ferrous materials including stainless steels. Plasma nitriding is carried out using a gas mixture of nitrogen and hydrogen gas at sub atmospheric pressures hence, making it eco-friendly in nature. Plasma nitriding allows modification of the surface layers and hardness profiles by changing the gas mixture and temperature. The wide applicable temperature range enables a multitude of applications, beyond the possibilities of gas or salt bath processes. This has led to numerous applications of this process in industries such as the manufacture of machine parts for plastics and food processing, packaging and tooling as well as pumps and hydraulic, machine

Advancing liquid metal reactor technology with nitride fuels

International Nuclear Information System (INIS)

Lyon, W.F.; Baker, R.B.; Leggett, R.D.; Matthews, R.B.

1991-08-01

A review of the use of nitride fuels in liquid metal fast reactors is presented. Past studies indicate that both uranium nitride and uranium/plutonium nitride possess characteristics that may offer enhanced performance, particularly in the area of passive safety. To further quantify these effects, the analysis of a mixed-nitride fuel system utilizing the geometry and power level of the US Advanced Liquid Metal Reactor as a reference is described. 18 refs., 2 figs., 2 tabs

Molten salt synthesis of sodium lithium titanium oxide anode material for lithium ion batteries

Energy Technology Data Exchange (ETDEWEB)

Yin, S.Y., E-mail: yshy2004@hotmail.com [College of Environmental and Biological Engineering, Wuhan Technology and Business University, Wuhan 430065 (China); Feng, C.Q. [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry of Education Key Laboratory for Synthesis and Applications of Organic Functional Molecules, Hubei University, Wuhan 430062 (China); Wu, S.J.; Liu, H.L.; Ke, B.Q. [College of Environmental and Biological Engineering, Wuhan Technology and Business University, Wuhan 430065 (China); Zhang, K.L. [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Chen, D.H. [College of Environmental and Biological Engineering, Wuhan Technology and Business University, Wuhan 430065 (China); Hubei Key Laboratory for Catalysis and Material Science, College of Chemistry and Material Science, South Central University for Nationalities, Wuhan 430074, Hubei (China)

2015-09-05

Highlights: • Na{sub 2}Li{sub 2}Ti{sub 6}O{sub 12} has been successfully synthesized via a molten salt route. • Calcination temperature is an important effect on the component and microstructure of the product. • Pure phase Na{sub 2}Li{sub 2}Ti{sub 6}O{sub 12} could be obtained at 700 °C for 2 h. - Abstract: The sodium lithium titanium oxide with composition Na{sub 2}Li{sub 2}Ti{sub 6}O{sub 14} has been synthesized by a molten salt synthesis method using sodium chloride and potassium chloride mixture as a flux medium. Synthetic variables on the synthesis, such as sintering temperature, sintering time and the amount of lithium carbonate, were intensively investigated. Powder X-ray diffraction and scanning electron microscopy images of the reaction products indicates that pure phase sodium lithium titanium oxide has been obtained at 700 °C, and impure phase sodium hexatitanate with whiskers produced at higher temperature due to lithium evaporative losses. The results of cyclic voltammetry and discharge–charge tests demonstrate that the synthesized products prepared at various temperatures exhibited electrochemical diversities due to the difference of the components. And the sample obtained at 700 °C revealed highly reversible insertion and extraction of Li{sup +} and displayed a single potential plateau at around 1.3 V. The product obtained at 700 °C for 2 h exhibits good cycling properties and retains the specific capacity of 62 mAh g{sup −1} after 500 cycles.

Tribocorrosion studies of metallic biomaterials: The effect of plasma nitriding and DLC surface modifications.

Science.gov (United States)

Zhao, Guo-Hua; Aune, Ragnhild E; Espallargas, Nuria

2016-10-01

The medical grade pure titanium, stainless steel and CoCrMo alloy have been utilized as biomaterials for load-bearing orthopedic prosthesis. The conventional surgery metals suffer from a combined effect of wear and corrosion once they are implanted, which may significantly accelerate the material degradation process. In this work, the tribocorrosion performance of the metallic biomaterials with different surface modifications was studied in the simulated body fluid for the purpose of investigating the effect of the surface treatments on the tribocorrosion performance and eventually finding the most suitable implantation materials. The metals were subjected to surface modifications by plasma nitriding in different treatment temperatures or physical vapor deposition (PVD) to produce diamond-like carbon (DLC) coating, respectively. The dry wear and tribocorrosion properties of the samples were evaluated by using a reciprocating ball-on-disc tribometer equipped with an electrochemical cell. Prior to the tribocorrosion tests, their electrochemical behavior was measured by the potentiodynamic polarization in phosphate buffer saline (PBS) solution at room temperature. Both stainless steel and CoCrMo after low temperature nitriding kept their passive nature by forming an expanded austenite phase. The DLC coated samples presented the low anodic corrosion current due to the chemical inertness of the carbon layer. During the tribocorrosion tests at open circuit potential, the untreated and low temperature nitrided samples exhibited significant potential drop towards the cathodic direction, which was a result of the worn out of the passive film. Galvanic coupling was established between the depassivated (worn) area and the still passive (unworn) area, making the materials suffered from wear-accelerated corrosion. The DLC coating performed as a solid lubricant in both dry wear and tribocorrosion tests, and the resulting wear after the tests was almost negligible. Copyright �

Exploring electrolyte preference of vanadium nitride supercapacitor electrodes

Energy Technology Data Exchange (ETDEWEB)

Wang, Bo; Chen, Zhaohui; Lu, Gang [Department of Electrical Engineering and Automation, Luoyang Institute of Science and Technology, Luoyang 471023 (China); Wang, Tianhu [School of Electrical Information and Engineering, Jiangsu University of Technology, Changzhou 213001 (China); Ge, Yunwang, E-mail: ywgelit@126.com [Department of Electrical Engineering and Automation, Luoyang Institute of Science and Technology, Luoyang 471023 (China)

2016-04-15

Highlights: • Hierarchical VN nanostructures were prepared on graphite foam. • Electrolyte preference of VN supercapacitor electrodes was explored. • VN showed better capacitive property in organic and alkaline electrolytes than LiCl. - Abstract: Vanadium nitride hierarchical nanostructures were prepared through an ammonia annealing procedure utilizing vanadium pentoxide nanostructures grown on graphite foam. The electrochemical properties of hierarchical vanadium nitride was tested in aqueous and organic electrolytes. As a result, the vanadium nitride showed better capacitive energy storage property in organic and alkaline electrolytes. This work provides insight into the charge storage process of vanadium nitride and our findings can shed light on other transition metal nitride-based electrochemical energy storage systems.

Modeling the Gas Nitriding Process of Low Alloy Steels

Science.gov (United States)

Yang, M.; Zimmerman, C.; Donahue, D.; Sisson, R. D.

2013-07-01

The effort to simulate the nitriding process has been ongoing for the last 20 years. Most of the work has been done to simulate the nitriding process of pure iron. In the present work a series of experiments have been done to understand the effects of the nitriding process parameters such as the nitriding potential, temperature, and time as well as surface condition on the gas nitriding process for the steels. The compound layer growth model has been developed to simulate the nitriding process of AISI 4140 steel. In this paper the fundamentals of the model are presented and discussed including the kinetics of compound layer growth and the determination of the nitrogen diffusivity in the diffusion zone. The excellent agreements have been achieved for both as-washed and pre-oxided nitrided AISI 4140 between the experimental data and simulation results. The nitrogen diffusivity in the diffusion zone is determined to be constant and only depends on the nitriding temperature, which is ~5 × 10-9 cm2/s at 548 °C. It proves the concept of utilizing the compound layer growth model in other steels. The nitriding process of various steels can thus be modeled and predicted in the future.

Synthesis of Uranium nitride powders using metal uranium powders

International Nuclear Information System (INIS)

Yang, Jae Ho; Kim, Dong Joo; Oh, Jang Soo; Rhee, Young Woo; Kim, Jong Hun; Kim, Keon Sik

2012-01-01

Uranium nitride (UN) is a potential fuel material for advanced nuclear reactors because of their high fuel density, high thermal conductivity, high melting temperature, and considerable breeding capability in LWRs. Uranium nitride powders can be fabricated by a carbothermic reduction of the oxide powders, or the nitriding of metal uranium. The carbothermic reduction has an advantage in the production of fine powders. However it has many drawbacks such as an inevitable engagement of impurities, process burden, and difficulties in reusing of expensive N 15 gas. Manufacturing concerns issued in the carbothermic reduction process can be solved by changing the starting materials from oxide powder to metals. However, in nitriding process of metal, it is difficult to obtain fine nitride powders because metal uranium is usually fabricated in the form of bulk ingots. In this study, a simple reaction method was tested to fabricate uranium nitride powders directly from uranium metal powders. We fabricated uranium metal spherical powder and flake using a centrifugal atomization method. The nitride powders were obtained by thermal treating those metal particles under nitrogen containing gas. We investigated the phase and morphology evolutions of powders during the nitriding process. A phase analysis of nitride powders was also a part of the present work

Electrochemical Solution Growth of Magnetic Nitrides

Energy Technology Data Exchange (ETDEWEB)

Monson, Todd C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pearce, Charles [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2014-10-01

Magnetic nitrides, if manufactured in bulk form, would provide designers of transformers and inductors with a new class of better performing and affordable soft magnetic materials. According to experimental results from thin films and/or theoretical calculations, magnetic nitrides would have magnetic moments well in excess of current state of the art soft magnets. Furthermore, magnetic nitrides would have higher resistivities than current transformer core materials and therefore not require the use of laminates of inactive material to limit eddy current losses. However, almost all of the magnetic nitrides have been elusive except in difficult to reproduce thin films or as inclusions in another material. Now, through its ability to reduce atmospheric nitrogen, the electrochemical solution growth (ESG) technique can bring highly sought after (and previously inaccessible) new magnetic nitrides into existence in bulk form. This method utilizes a molten salt as a solvent to solubilize metal cations and nitrogen ions produced electrochemically and form nitrogen compounds. Unlike other growth methods, the scalable ESG process can sustain high growth rates (~mm/hr) even under reasonable operating conditions (atmospheric pressure and 500 °C). Ultimately, this translates into a high throughput, low cost, manufacturing process. The ESG process has already been used successfully to grow high quality GaN. Below, the experimental results of an exploratory express LDRD project to access the viability of the ESG technique to grow magnetic nitrides will be presented.

Simulation of the Nitriding Process

Science.gov (United States)

Krukovich, M. G.

2004-01-01

Simulation of the nitriding process makes it possible to solve many practical problems of process control, prediction of results, and development of new treatment modes and treated materials. The presented classification systematizes nitriding processes and processes based on nitriding, enables consideration of the theory and practice of an individual process in interrelation with other phenomena, outlines ways for intensification of various process variants, and gives grounds for development of recommendations for controlling the structure and properties of the obtained layers. The general rules for conducting the process and formation of phases in the layer and properties of the treated surfaces are used to create a prediction computational model based on analytical, numerical, and empirical approaches.

Characterization of plasma nitrided layers produced on sintered iron

Directory of Open Access Journals (Sweden)

Marcos Alves Fontes

2014-07-01

Full Text Available Plasma nitriding is a thermo-physical-chemical treatment process, which promotes surface hardening, caused by interstitial diffusion of atomic nitrogen into metallic alloys. In this work, this process was employed in the surface modification of a sintered ferrous alloy. Scanning electron microscopy (SEM, X-ray diffraction (XRD analyses, and wear and microhardness tests were performed on the samples submitted to ferrox treatment and plasma nitriding carried out under different conditions of time and temperature. The results showed that the nitride layer thickness is higher for all nitrided samples than for ferrox treated samples, and this layer thickness increases with nitriding time and temperature, and temperature is a more significant variable. The XRD analysis showed that the nitrided layer, for all samples, near the surface consists in a mixture of γ′-Fe4N and ɛ-Fe3N phases. Both wear resistance and microhardness increase with nitriding time and temperature, and temperature influences both the characteristics the most.

Whisker growth: a new mechanism for helium blistering of surfaces in complex radiation environments

International Nuclear Information System (INIS)

McDonell, W.R.

1978-01-01

Implantation of helium concurrent with the generation of large numbers of displaced atoms in surface layers of materials exposed to 252 Cf α-particles and fission fragments produces a unique form of low temperature surface blistering. The purpose of this paper is to formulate a basis for the whisker-growth mechanism for helium blistering as an aid to the specification of conditions under which the mechanism might apply

Innovative boron nitride-doped propellants

Directory of Open Access Journals (Sweden)

Thelma Manning

2016-04-01

Full Text Available The U.S. military has a need for more powerful propellants with balanced/stoichiometric amounts of fuel and oxidants. However, balanced and more powerful propellants lead to accelerated gun barrel erosion and markedly shortened useful barrel life. Boron nitride (BN is an interesting potential additive for propellants that could reduce gun wear effects in advanced propellants (US patent pending 2015-026P. Hexagonal boron nitride is a good lubricant that can provide wear resistance and lower flame temperatures for gun barrels. Further, boron can dope steel, which drastically improves its strength and wear resistance, and can block the formation of softer carbides. A scalable synthesis method for producing boron nitride nano-particles that can be readily dispersed into propellants has been developed. Even dispersion of the nano-particles in a double-base propellant has been demonstrated using a solvent-based processing approach. Stability of a composite propellant with the BN additive was verified. In this paper, results from propellant testing of boron nitride nano-composite propellants are presented, including closed bomb and wear and erosion testing. Detailed characterization of the erosion tester substrates before and after firing was obtained by electron microscopy, inductively coupled plasma and x-ray photoelectron spectroscopy. This promising boron nitride additive shows the ability to improve gun wear and erosion resistance without any destabilizing effects to the propellant. Potential applications could include less erosive propellants in propellant ammunition for large, medium and small diameter fire arms.

Zirconia toughened SiC whisker reinforced alumina composites small business innovation research

Science.gov (United States)

Loutfy, R. O.; Stuffle, K. L.; Withers, J. C.; Lee, C. T.

1987-01-01

The objective of this phase 1 project was to develop a ceramic composite with superior fracture toughness and high strength, based on combining two toughness inducing materials: zirconia for transformation toughening and SiC whiskers for reinforcement, in a controlled microstructure alumina matrix. The controlled matrix microstructure is obtained by controlling the nucleation frequency of the alumina gel with seeds (submicron alpha-alumina). The results demonstrate the technical feasibility of producing superior binary composites (Al2O3-ZrO2) and tertiary composites (Al2O3-ZrO2-SiC). Thirty-two composites were prepared, consolidated, and fracture toughness tested. Statistical analysis of the results showed that: (1) the SiC type is the key statistically significant factor for increased toughness; (2) sol-gel processing with a-alumina seed had a statistically significant effect on increasing toughness of the binary and tertiary composites compared to the corresponding mixed powder processing; and (3) ZrO2 content within the range investigated had a minor effect. Binary composites with an average critical fracture toughness of 6.6MPam sup 1/2, were obtained. Tertiary composites with critical fracture toughness in the range of 9.3 to 10.1 MPam sup 1/2 were obtained. Results indicate that these composites are superior to zirconia toughened alumina and SiC whisker reinforced alumina ceramic composites produced by conventional techniques with similar composition from published data.

Influence of nitriding atmosphere on the modification of surface titanium with focus on the behavior of blood platelets adhesion

International Nuclear Information System (INIS)

Vitoriano, J.O.; Alves, C.; Braz, D.C.; Camara, R.B.G.; Rocha, H.A.O.

2014-01-01

The present study aimed to analyze the influence of surface modification of titanium on the adhesion of blood platelets, through techniques of adhesion and morphological analyzes. Discs of titanium grade II received different surface treatments with plasma of Ar + N_2 + H_2 and Ar + H_2, forming two experimental groups including only polished samples used as standard. Before and after treatment the samples were characterized according to topography, crystalline structure and wettability, using atomic force microscopy, X-ray diffraction, Raman spectroscopy and testing of sessile drop, respectively. Platelet rich plasma (PRP) was applied on the modified surfaces in a culture plates. Images obtained by electron microscopy of adhered platelets were analyzed to verify the behavior of platelets in the different experimental conditions. (author)

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).

Generation and Characteristics of IV-VI transition Metal Nitride and Carbide Nanoparticles using a Reactive Mesoporous Carbon Nitride

KAUST Repository

Alhajri, Nawal Saad

2016-02-22

Interstitial nitrides and carbides of early transition metals in groups IV–VI exhibit platinum-like electronic structures, which make them promising candidates to replace noble metals in various catalytic reactions. Herein, we present the preparation and characterization of nano-sized transition metal nitries and carbides of groups IV–VI (Ti, V, Nb, Ta, Cr, Mo, and W) using mesoporous graphitic carbon nitride (mpg-C3N4), which not only provides confined spaces for restricting primary particle size but also acts as a chemical source of nitrogen and carbon. We studied the reactivity of the metals with the template under N2 flow at 1023 K while keeping the weight ratio of metal to template constant at unity. The produced nanoparticles were characterized by powder X-ray diffraction, CHN elemental analysis, nitrogen sorption, X-ray photoelectron spectroscopy, and transmission electron microscopy. The results show that Ti, V, Nb, Ta, and Cr form nitride phases with face centered cubic structure, whereas Mo and W forme carbides with hexagonal structures. The tendency to form nitride or carbide obeys the free formation energy of the transition metal nitrides and carbides. This method offers the potential to prepare the desired size, shape and phase of transition metal nitrides and carbides that are suitable for a specific reaction, which is the chief objective of materials chemistry.

Preparation and study of the nitrides and mixed carbide-nitrides of uranium and of plutonium

International Nuclear Information System (INIS)

Anselin, F.

1966-06-01

A detailed description is given of a simple method for preparing uranium and plutonium nitrides by the direct action of nitrogen under pressure at moderate temperatures (about 400 C) on the partially hydrogenated bulk metal. It is shown that there is complete miscibility between the UN and PuN phases. The variations in the reticular parameters of the samples as a function of temperature and in the presence of oxide have been used to detect and evaluate the solubility of oxygen in the different phases. A study has been made of the sintering of these nitrides as a function of the preparation conditions with or without sintering additives. A favorable but non-reproducible, effect has been found for traces of oxide. The best results were obtained for pure UN at 1600 C (96 per cent theoretical density) on condition that a well defined powder, was used. The criterion used is the integral width of the X-ray diffraction lines. The compounds UN and PuN are completely miscible with the corresponding carbides. This makes it possible to prepare carbide-nitrides of the general formula (U,Pu) (C,N) by solid-phase diffusion, at around 1400 C. The sintering of these carbide-nitrides is similar to that of the carbides if the nitrogen content is low; in particular, nickel is an efficient sintering agent. For high contents, the sintering is similar to that of pure nitrides. (author) [fr

Bulletin of Materials Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

The stainless steels, in general, are considered to be difficult-to-machine materials. In order to machine these materials the surface of the tool is generally coated with physical vapour deposition (PVD) hard coatings such as titanium nitride (TiN), titanium aluminum nitride (TiAlN), etc. The adhesion is of vital importance for ...

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.

Preparation and characteristics of various rare earth nitrides

International Nuclear Information System (INIS)

Imamura, H.; Imahashi, T.; Zaimi, M.; Sakata, Y.

2008-01-01

Active nanocrystalline nitrides of EuN and YbN with high surface areas were successfully prepared by the thermal decomposition of the rare earth amides (Eu(NH 2 ) 2 , Yb(NH 2 ) 2 and Yb(NH 2 ) 3 ). For the preparation of CeN, PrN and NdN, the direct reaction of the rare earth metals with ammonia was extensively studied to determine optimal conditions. In the reaction of rare earth metals with ammonia, hydrides besides the nitrides were competitively formed. The reaction conditions such as temperatures and ratios of ammonia to rare earth metal were crucial in preferential formation of nitride. The nanocrystalline YbN and EuN readily absorbed large amounts of ammonia even at room temperature upon contact with ammonia (13.3 kPa). The absorbed ammonia existed in at least two forms on/in the nitride; the one was surface-adsorbed ammonia and the other ammonia absorbed in the nitride in a decomposed state. The properties of ammonia absorbed by the nitride were further evaluated by temperature-programmed desorption (TPD), FT-IR and XRD techniques

Experimental test of 200 W Hall thruster with titanium wall

Science.gov (United States)

Ding, Yongjie; Sun, Hezhi; Peng, Wuji; Xu, Yu; Wei, Liqiu; Li, Hong; Li, Peng; Su, Hongbo; Yu, Daren

2017-05-01

We designed a 200 W Hall thruster based on the technology of pushing down a magnetic field with two permanent magnetic rings. Boron nitride (BN) is an important insulating wall material for Hall thrusters. The discharge characteristics of the designed Hall thruster were studied by replacing BN with titanium (Ti). Experimental results show that the designed Hall thruster can discharge stably for a long time under a Ti channel. Experiments were performed to determine whether the channel and cathode are electrically connected. When the channel wall and cathode are insulated, the divergence angle of the plume increases, but the performance of the Hall thruster is improved in terms of thrust, specific impulse, anode efficiency, and thrust-to-power ratio. Ti exhibits a powerful antisputtering capability, a low emanation rate of gas, and a large structural strength, making it a potential candidate wall material in the design of low-power Hall thrusters.

Method of preparation of uranium nitride

Science.gov (United States)

Kiplinger, Jaqueline Loetsch; Thomson, Robert Kenneth James

2013-07-09

Method for producing terminal uranium nitride complexes comprising providing a suitable starting material comprising uranium; oxidizing the starting material with a suitable oxidant to produce one or more uranium(IV)-azide complexes; and, sufficiently irradiating the uranium(IV)-azide complexes to produce the terminal uranium nitride complexes.

Microstructural Characterization of Low Temperature Gas Nitrided Martensitic Stainless Steel

DEFF Research Database (Denmark)

Fernandes, Frederico Augusto Pires; Christiansen, Thomas Lundin; Somers, Marcel A. J.

2015-01-01

The present work presents microstructural investigations of the surface zone of low temperature gas nitrided precipitation hardening martensitic stainless steel AISI 630. Grazing incidence X-ray diffraction was applied to investigate the present phases after successive removal of very thin sections...... of the sample surface. The development of epsilon nitride, expanded austenite and expanded martensite resulted from the low temperature nitriding treatments. The microstructural features, hardness and phase composition are discussed with emphasis on the influence of nitriding duration and nitriding potential....

Pyrochemical reprocessing of nitride fuel

International Nuclear Information System (INIS)

Nakazono, Yoshihisa; Iwai, Takashi; Arai, Yasuo

2004-01-01

Electrochemical behavior of actinide nitrides in LiCl-KCl eutectic melt was investigated in order to apply pyrochemical process to nitride fuel cycle. The electrode reaction of UN and (U, Nd)N was examined by cyclic voltammetry. The observed rest potential of (U, Nd)N depended on the equilibrium of U 3+ /UN and was not affected by the addition of NdN of 8 wt.%. (author)

Microstructural stability and thermomechanical processing of boron modified beta titanium alloys

Science.gov (United States)

Cherukuri, Balakrishna

One of the main objectives during primary processing of titanium alloys is to reduce the prior beta grain size. Producing an ingot with smaller prior beta grain size could potentially eliminate some primary processing steps and thus reduce processing cost. Trace additions of boron have been shown to decrease the as-cast grain size in alpha + beta titanium alloys. The primary focus of this dissertation is to investigate the effect of boron on microstructural stability and thermomechanical processing in beta titanium alloys. Two metastable beta titanium alloys: Ti-15Mo-2.6Nb-3Al-0.2Si (Beta21S) and Ti-5Al-5V-5Mo-3Cr (Ti5553) with 0.1 wt% B and without boron additions were used in this investigation. Significant grain refinement of the as-cast microstructure and precipitation of TiB whiskers along the grain boundaries was observed with boron additions. Beta21S and Beta21S-0.1B alloys were annealed above the beta transus temperature for different times to investigate the effect of boron on grain size stability. The TiB precipitates were very effective in restricting the beta grain boundary mobility by Zener pinning. A model has been developed to predict the maximum grain size as a function of TiB size, orientation, and volume fraction. Good agreement was obtained between model predictions and experimental results. Beta21S alloys were solution treated and aged for different times at several temperatures below the beta transus to study the kinetics of alpha precipitation. Though the TiB phase did not provide any additional nucleation sites for alpha precipitation, the grain refinement obtained by boron additions resulted in accelerated aging. An investigation of the thermomechanical processing behavior showed different deformation mechanisms above the beta transus temperature. The non-boron containing alloys showed a non-uniform and fine recrystallized necklace structure at grain boundaries whereas uniform intragranular recrystallization was observed in boron containing

Fusion bonding of silicon nitride surfaces

DEFF Research Database (Denmark)

Reck, Kasper; Østergaard, Christian; Thomsen, Erik Vilain

2011-01-01

While silicon nitride surfaces are widely used in many micro electrical mechanical system devices, e.g. for chemical passivation, electrical isolation or environmental protection, studies on fusion bonding of two silicon nitride surfaces (Si3N4–Si3N4 bonding) are very few and highly application...

EDITORIAL: Non-polar and semipolar nitride semiconductors Non-polar and semipolar nitride semiconductors

Science.gov (United States)

Han, Jung; Kneissl, Michael

2012-02-01

Throughout the history of group-III-nitride materials and devices, scientific breakthroughs and technological advances have gone hand-in-hand. In the late 1980s and early 1990s, the discovery of the nucleation of smooth (0001) GaN films on c-plane sapphire and the activation of p-dopants in GaN led very quickly to the realization of high-brightness blue and green LEDs, followed by the first demonstration of GaN-based violet laser diodes in the mid 1990s. Today, blue InGaN LEDs boast record external quantum efficiencies exceeding 80% and the emission wavelength of the InGaN-based laser diode has been pushed into the green spectral range. Although these tremenduous advances have already spurred multi-billion dollar industries, there are still a number of scientific questions and technological issues that are unanswered. One key challenge is related to the polar nature of the III-nitride wurtzite crystal. Until a decade ago all research activities had almost exclusively concentrated on (0001)-oriented polar GaN layers and heterostructures. Although the device characteristics seem excellent, the strong polarization fields at GaN heterointerfaces can lead to a significant deterioration of the device performance. Triggered by the first demonstration non-polar GaN quantum wells grown on LiAlO2 by Waltereit and colleagues in 2000, impressive advances in the area of non-polar and semipolar nitride semiconductors and devices have been achieved. Today, a large variety of heterostructures free of polarization fields and exhibiting exceptional electronic and optical properties have been demonstrated, and the fundamental understanding of polar, semipolar and non-polar nitrides has made significant leaps forward. The contributions in this Semiconductor Science and Technology special issue on non-polar and semipolar nitride semiconductors provide an impressive and up-to-date cross-section of all areas of research and device physics in this field. The articles cover a wide range of

Plasma nitridation optimization for sub-15 A gate dielectrics

NARCIS (Netherlands)

Cubaynes, F.N; Schmitz, Jurriaan; van der Marel, C.; Snijders, J.H.M.; Veloso, A.; Rothschild, A.; Olsen, C.; Date, L.

The work investigates the impact of plasma nitridation process parameters upon the physical properties and upon the electrical performance of sub-15 A plasma nitrided gate dielectrics. The nitrogen distribution and chemical bonding of ultra-thin plasma nitrided films have been investigated using

Diagnostic of corrosion–erosion evolution for [Hf-Nitrides/V-Nitrides]n structures

Energy Technology Data Exchange (ETDEWEB)

Escobar, C.; Villarreal, M. [Thin Film Group, Universidad del Valle, A.A. 25360, Cali (Colombia); Caicedo, J.C., E-mail: jcaicedoangulo1@gmail.com [Powder Metallurgy and Processing of Solid Recycled Research Group, Universidad del Valle, Cali (Colombia); Aperador, W. [Ingeniería Mecatrónica, Universidad Militar Nueva Granada, Bogotá (Colombia); Caicedo, H.H. [Department of Bioengineering, University of Illinois at Chicago, IL 60612 (United States); Department of Anatomy and Cell Biology, University of Illinois at Chicago, IL 60612 (United States); Prieto, P. [Thin Film Group, Universidad del Valle, A.A. 25360, Cali (Colombia); Center of Excellence for Novel Materials, CENM, Cali (Colombia)

2013-10-31

HfN/VN multilayered systems were grown on 4140 steel substrates with the aim to improve their electrochemical behavior. The multilayered coatings were grown via reactive r.f. magnetron sputtering technique by systematically varying the bilayer period (Λ) and the bilayer number (n) while maintaining constant the total coating thickness (∼ 1.2 μm). The coatings were characterized by X-ray diffraction (XRD), and electron microscopy. The electrochemical properties were studied by Electrochemical Impedance Spectroscopy and Tafel curves. XRD results showed preferential growth in the face-centered cubic (111) crystal structure for [HfN/VN]{sub n} multilayered coatings. The maximum corrosion resistance was obtained for coatings with (Λ) equal to 15 nm, corresponding to bilayer n = 80. Polarization resistance and corrosion rate was around 112.19 kΩ cm{sup 2} and 0.094*10{sup −3} mmy respectively; moreover, these multilayered system showed a decrease of 80% on mass loss due to the corrosive–erosive process, in relation to multilayered systems with n = 1 and Λ = 1200. HfN/VN multilayers have been designed and deposited on Si (100) and AISI 4140 steel substrates with bilayer periods (Λ) in a broad range, from nanometers to hundreds of nanometers to study the microstructural evolution and electrochemical progress with decreasing bilayer thickness. - Highlights: • Enhancements on surface electrochemical properties and response to surface corrosion attack. • Superficial phenomenon that occurs in corrosion surface of [Hf-Nitrides/V-Nitrides]n • Corrosion–erosion evolution for [Hf-Nitrides/V-Nitrides]n structures.

Diagnostic of corrosion–erosion evolution for [Hf-Nitrides/V-Nitrides]n structures

International Nuclear Information System (INIS)

Escobar, C.; Villarreal, M.; Caicedo, J.C.; Aperador, W.; Caicedo, H.H.; Prieto, P.

2013-01-01

HfN/VN multilayered systems were grown on 4140 steel substrates with the aim to improve their electrochemical behavior. The multilayered coatings were grown via reactive r.f. magnetron sputtering technique by systematically varying the bilayer period (Λ) and the bilayer number (n) while maintaining constant the total coating thickness (∼ 1.2 μm). The coatings were characterized by X-ray diffraction (XRD), and electron microscopy. The electrochemical properties were studied by Electrochemical Impedance Spectroscopy and Tafel curves. XRD results showed preferential growth in the face-centered cubic (111) crystal structure for [HfN/VN] n multilayered coatings. The maximum corrosion resistance was obtained for coatings with (Λ) equal to 15 nm, corresponding to bilayer n = 80. Polarization resistance and corrosion rate was around 112.19 kΩ cm 2 and 0.094*10 −3 mmy respectively; moreover, these multilayered system showed a decrease of 80% on mass loss due to the corrosive–erosive process, in relation to multilayered systems with n = 1 and Λ = 1200. HfN/VN multilayers have been designed and deposited on Si (100) and AISI 4140 steel substrates with bilayer periods (Λ) in a broad range, from nanometers to hundreds of nanometers to study the microstructural evolution and electrochemical progress with decreasing bilayer thickness. - Highlights: • Enhancements on surface electrochemical properties and response to surface corrosion attack. • Superficial phenomenon that occurs in corrosion surface of [Hf-Nitrides/V-Nitrides]n • Corrosion–erosion evolution for [Hf-Nitrides/V-Nitrides]n structures

A randomized study to compare bioactive titanium stents and everolimus-eluting stents in diabetic patients (TITANIC XV): 1-year results.

Science.gov (United States)

López-Mínguez, José R; Nogales-Asensio, Juan M; Doncel-Vecino, Luis J; Merchán-Herrera, Antonio; Pomar-Domingo, Francisco; Martínez-Romero, Pedro; Fernández-Díaz, José A; Valdesuso-Aguilar, Raúl; Moreu-Burgos, José; Díaz-Fernández, José

2014-07-01

Up to 25% of patients who undergo a percutaneous coronary intervention show some limitation in the use of drug-eluting stents. The aim of this study was to evaluate if titanium-nitride-oxide-coated stents could be a good alternative to everolimus-eluting stents in diabetic patients. A total of 173 diabetic patients with lesions at moderate risk of restenosis (exclusion criteria: diameter 28 mm in vessels < 3mm, chronic occlusion) were randomized to a titanium group (83 patients) or an everolimus group (90 patients). Baseline characteristics were well balanced; 28.3% of patients were insulin dependent. At 1 year, the incidence of major adverse cardiac events (death, nonfatal myocardial infarction, stroke, or repeat target vessel revascularization) was significantly higher in the titanium group than in the everolimus group (total, 14.5% vs 4.4%; P = .02; noninsulin-dependent subgroup, 9.7% vs 3.2%; P = .14; insulin-dependent subgroup, 28.6% vs 7.1%; P = .04). The incidence of death, nonfatal myocardial infarction, stroke, or any revascularization was 16.9% in the titanium group and 7.8% in the everolimus group (P = .06). Target lesion and vessel revascularizations occurred in 8.4% compared with 3.3% (P = .15) and in 13.3% compared with 3.3% (P = .01) in the titanium and everolimus groups, respectively. Angiographic follow-up at 9 months showed significantly less late lumen loss in the everolimus group (in-segment, 0.52 [standard deviation, 0.58) mm vs -0.05 [0.32] mm; in-stent, 0.76 [0.54] mm vs 0.13 [0.31] mm; P < .0001). The everolimus-eluting stent is superior to the titanium stent for clinical and angiographic end points in diabetic patients with lesions at moderate risk of restenosis. Copyright © 2013 Sociedad Española de Cardiología. Published by Elsevier Espana. All rights reserved.

Improved dental implant drill durability and performance using heat and wear resistant protective coatings.

Science.gov (United States)

Er, Nilay; Alkan, Alper; İlday, Serim; Bengu, Erman

2018-03-02

Dental implant drilling procedure is an essential step for implant surgery and frictional heat appeared in bone during drilling is a key factor affecting the success of an implant. The aim of this study is to increase the dental implant drill lifetime and performance using heat- and wear-resistant protective coatings hence to decrease the alveolar bone temperature caused by the dental implant drilling procedure. Commercially obtained stainless steel drills were coated with titanium aluminum nitride, diamond-like carbon, titanium boron nitride, and boron nitride coatings via magnetron-sputter deposition. Drilling procedure was performed on a bovine femoral cortical bone under the conditions mimicking clinical practice, where the tests were performed both under water-assisted cooling and under the conditions without any cooling was applied. Coated drill performances and durabilities were compared to that of three commonly used commercial drills which surfaces are made from namely; zirconia, black diamond and stainless steel. Protective coatings with boron nitride, titanium boron nitride and diamond-like carbon have significantly improved drill performance and durability. Especially boron nitride-coated drills have performed within safe bone temperature limits for 50 drillings even without any cooling is applied. Titanium aluminium nitride coated drills did not show any improvement over commercially obtained stainless steel drills. Surface modification using heat and wear resistant coatings is an easy and highly effective way to improve implant drill performance and durability, which can reflect positively on surgical procedure and healing period afterwards. The noteworthy success of different types of coatings is novel and likely to be applicable to various other medical systems.

Nano-particulate Aluminium Nitride/Al: An Efficient and Versatile Heterogeneous Catalyst for the Synthesis of Biginelli Scaffolds

Science.gov (United States)

Tekale, S. U.; Tekale, A. B.; Kanhe, N. S.; Bhoraskar, S. V.; Pawar, R. P.

2011-12-01

Nano-particulate aluminium nitride/Al (7:1) is reported as a new heterogeneous solid acid catalyst for the synthesis of 3, 4-dihydroxypyrimidi-2-(1H)-ones and their sulphur analogues using the Biginelli reaction. This method involves short reaction time, easy separation, high yields and purity of products.

Additive Manufacturing of Dense Hexagonal Boron Nitride Objects

Energy Technology Data Exchange (ETDEWEB)

Marquez Rossy, Andres E [ORNL; Armstrong, Beth L [ORNL; Elliott, Amy M [ORNL; Lara-Curzio, Edgar [ORNL

2017-05-12

The feasibility of manufacturing hexagonal boron nitride objects via additive manufacturing techniques was investigated. It was demonstrated that it is possible to hot-extrude thermoplastic filaments containing uniformly distributed boron nitride particles with a volume concentration as high as 60% and that these thermoplastic filaments can be used as feedstock for 3D-printing objects using a fused deposition system. Objects 3D-printed by fused deposition were subsequently sintered at high temperature to obtain dense ceramic products. In a parallel study the behavior of hexagonal boron nitride in aqueous solutions was investigated. It was shown that the addition of a cationic dispersant to an azeotrope enabled the formulation of slurries with a volume concentration of boron nitride as high as 33%. Although these slurries exhibited complex rheological behavior, the results from this study are encouraging and provide a pathway for manufacturing hexagonal boron nitride objects via robocasting.

Aluminum nitride insulating films for MOSFET devices

Science.gov (United States)

Lewicki, G. W.; Maserjian, J.

1972-01-01

Application of aluminum nitrides as electrical insulator for electric capacitors is discussed. Electrical properties of aluminum nitrides are analyzed and specific use with field effect transistors is defined. Operational limits of field effect transistors are developed.

Significantly Enhanced Dielectric Performances and High Thermal Conductivity in Poly(vinylidene fluoride)-Based Composites Enabled by SiC@SiO2 Core-Shell Whiskers Alignment.

Science.gov (United States)

He, Dalong; Wang, Yao; Song, Silong; Liu, Song; Deng, Yuan

2017-12-27

Design of composites with ordered fillers arrangement results in anisotropic performances with greatly enhanced properties along a specific direction, which is a powerful tool to optimize physical properties of composites. Well-aligned core-shell SiC@SiO 2 whiskers in poly(vinylidene fluoride) (PVDF) matrix has been achieved via a modified spinning approach. Because of the high aspect ratio of SiC whiskers, strong anisotropy and significant enhancement in dielectric constant were observed with permittivity 854 along the parallel direction versus 71 along the perpendicular direction at 20 vol % SiC@SiO 2 loading, while little increase in dielectric loss was found due to the highly insulating SiO 2 shell. The anisotropic dielectric behavior of the composite is perfectly understood macroscopically to have originated from anisotropic intensity of interfacial polarization based on an equivalent circuit model of two parallel RC circuits connected in series. Furthermore, finite element simulations on the three-dimensional distribution of local electric field, polarization, and leakage current density in oriented SiC@SiO 2 /PVDF composites under different applied electrical field directions unambiguously revealed that aligned core-shell SiC@SiO 2 whiskers with a high aspect ratio significantly improved dielectric performances. Importantly, the thermal conductivity of the composite was synchronously enhanced over 7 times as compared to that of PVDF matrix along the parallel direction at 20 vol % SiC@SiO 2 whiskers loading. This study highlights an effective strategy to achieve excellent comprehensive properties for high-k dielectrics.

Nitride coating enhances endothelialization on biomedical NiTi shape memory alloy