Capacitive performance of molybdenum nitride/titanium nitride nanotube array for supercapacitor

Energy Technology Data Exchange (ETDEWEB)

Xie, Yibing, E-mail: ybxie@seu.edu.cn; Tian, Fang

2017-01-15

Highlights: • MoN{sub x}/TiN NTA is fully converted from MoO{sub 2}/TiO{sub 2} NTA by one-step nitridation process. • MoN{sub x}/TiN NTA is used as feasible electrode material of high-performance supercapacitor. • MoN{sub x}/TiN NTA shows high capacitance, rate capability and cycling stability. - Abstract: Molybdenum nitride (MoN{sub x}) depositing on titanium nitride nanotube array (TiN NTA) was designed as MoN{sub x}/TiN NTA for supercapacitor electrode material. MoN{sub x}/TiN NTA was fabricated by electrodepositing molybdenum oxide onto titanium dioxide NTA and one-step nitridation treatment in ammonia. MoN{sub x}/TiN NTA involved top-surface layer of MoN{sub x} nanoparticles and underlying layer of TiN NTA, which contributed to electric double layer capacitance in aqueous lithium-ion electrolyte solution. The specific capacitance was increased from 69.05 mF cm{sup −2} for TiN NTA to 121.50 mF cm{sup −2} for MoN{sub x}/TiN NTA at 0.3 mA cm{sup −2}, presenting the improved capacitance performance. MoN{sub x} exhibited the capacitance of 174.83 F g{sup −1} at 1.5 A g{sup −1} and slightly declined to 109.13 F g{sup −1} at 30 A g{sup −1}, presenting high rate capability. MoN{sub x}/TiN NTA exhibited the capacitance retention ratio of 93.8% at 3.0 mA cm{sup −2} after 1000 cycles, presenting high cycling stability. MoN{sub x}/TiN NTA could act as a promising electrode material of supercapacitor.

Tribological Characteristic of Titanium Alloy Surface Layers Produced by Diode Laser Gas Nitriding

Directory of Open Access Journals (Sweden)

Lisiecki A.

2016-06-01

Full Text Available In order to improve the tribological properties of titanium alloy Ti6Al4V composite surface layers Ti/TiN were produced during laser surface gas nitriding by means of a novel high power direct diode laser with unique characteristics of the laser beam and a rectangular beam spot. Microstructure, surface topography and microhardness distribution across the surface layers were analyzed. Ball-on-disk tests were performed to evaluate and compare the wear and friction characteristics of surface layers nitrided at different process parameters, base metal of titanium alloy Ti6Al4V and also the commercially pure titanium. Results showed that under dry sliding condition the commercially pure titanium samples have the highest coefficient of friction about 0.45, compared to 0.36 of titanium alloy Ti6Al4V and 0.1-0.13 in a case of the laser gas nitrided surface layers. The volume loss of Ti6Al4V samples under such conditions is twice lower than in a case of pure titanium. On the other hand the composite surface layer characterized by the highest wear resistance showed almost 21 times lower volume loss during the ball-on-disk test, compared to Ti6Al4V samples.

Corrosion-resistant titanium nitride coatings formed on stainless steel by ion-beam-assisted deposition

International Nuclear Information System (INIS)

Baba, K.; Hatada, R.

1994-01-01

Titanium films 70nm thick were deposited on austenitic type 316L stainless steel substrates, and these specimens were irradiated with titanium ions of energy 70kV at a fluence of 1x10 17 ioncm -2 , using a metal vapor vacuum arc (MEVVA) IV metallic ion source at room temperature. After irradiation, titanium nitride (TiN) films were deposited by titanium evaporation and simultaneous irradiation by a nitrogen ion beam, with transport ratios of Ti to N atoms from 0.5 to 10.0 and an ion acceleration voltage of 2kV. The preferred orientation of the TiN films varied from left angle 200 right angle to left angle 111 right angle normal to the surface when the transport ratio was increased. With the help of Auger electron spectroscopy, interfacial mixing was verified. Nitrogen atoms were present in the state of titanium nitride for all transport ratios from 0.5 up to 10.0. However, the chemical bonding state of titanium changed from titanium nitride to the metallic state with increasing transport ratio Ti/N. The corrosion behavior was evaluated in an aqueous solution of sulfuric acid saturated with oxygen, using multisweep cyclic voltammetry measurements. Thin film deposition of pure titanium and titanium implantation prior to TiN deposition have beneficial effects on the suppression of transpassive chromium dissolution. ((orig.))

Study of titanium nitride elasticity characteristics in the homogeneity range by ultrasonic resonance method

International Nuclear Information System (INIS)

Khidirov, I.; Khajdarov, T.

1995-01-01

Elasticity characteristics of cubic and tetragonal phases of titanium nitride in the homogeneity range were studied for the first time by ultrasonic resonance method. It is established that the Young modulus, the shift and volume module of cubic titanium nitride elasticity in the homogeneity range change nonlinearly with decrease in nitrogen concentration and correlate with concentration dependences of other physical properties.15 refs., 2 figs

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.)

Adhesion of non-selective CVD tungsten to silicon dioxide

International Nuclear Information System (INIS)

Woodruff, D.W.; Wilson, R.H.; Sanchez-Martinez, R.A.

1986-01-01

Adhesion of non-selective, CVD tungsten to silicon dioxide is a critical issue in the development of tungsten as a metalization for VLSI circuitry. Without special adhesion promoters, tungsten deposited from WF/sub 6/ and H/sub 2/ has typically failed a standard tape test over all types of silicon oxides and nitrides. The reasons for failure of thin films, and CVD tungsten in particular are explored along with standard techniques for improving adhesion of thin films. Experiments are reported which include a number of sputtered metals as adhesion promoters, as well as chemical and plasma treatment of the oxide surface. Sputtered molybdenum is clearly the superior adhesion promoting layer from these tests. Traditional adhesion layers such as chromium or titanium failed as adhesion layers for CVD tungsten possibly due to chemical reactions between the WF/sub 6/ and Cr or Ti

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.

Clean and polymer-free transfer of CVD-grown graphene films on hexagonal boron nitride substrates

Science.gov (United States)

Fujihara, Miho; Ogawa, Shun; Yoshimura, Shintaro; Inoue, Ryosuke; Maniwa, Yutaka; Taniguchi, Takashi; Watanabe, Kenji; Shinohara, Hisanori; Miyata, Yasumitsu

2017-05-01

This report describes the development of a solution-assisted, polymer-free transfer method and the characterization of chemical vapor deposition (CVD)-grown graphene on hexagonal boron nitride. Raman analysis reveals that polymer-free samples have small variations in G- and 2D-mode Raman frequencies and are minimally affected by charge doping as observed for clean exfoliated graphene. Electrical measurements indicate that charge doping, hysteresis, and carrier scattering are suppressed in polymer-free samples. The results demonstrate that this method provides a simple and effective way to prepare clean heterostructures of CVD-grown, large-area graphene and other two-dimensional materials.

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

Directory of Open Access Journals (Sweden)

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.

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.

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

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.

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...

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...

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

CVD refractory metals and alloys for space nuclear power application

International Nuclear Information System (INIS)

Yang, L.; Gulden, T.D.; Watson, J.F.

1984-01-01

CVD technology has made significant contributions to the development of space nuclear power systems during the period 1962 to 1972. For the in-core thermionic concept, CVD technology is essential to the fabrication of the tungsten electron emitter. For the liquid metal cooled fuel pin using uranium nitride as fuel and T-111 and Nb-1 Zr as cladding, a tungsten barrier possibly produced by CVD methods is essential to the fuel-cladding compatibility at the designed operating temperature. Space power reactors may use heat pipes to transfer heat from the reactor core to the conversion system. CVD technology has been used for fabricating the heat pipe used as cross-flow heat exchanger, including the built-in channels on the condenser wall for liquid lithium return. 28 references, 17 figures

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.

Tribological Characteristics and Applications of Superhard Coatings: CVD Diamond, DLC, and c-BN

Science.gov (United States)

Miyoshi, Kazuhisa; Murakawa, Masao; Watanabe, Shuichi; Takeuchi, Sadao; Wu, Richard L. C.

1999-01-01

Results of fundamental research on the tribological properties of chemical-vapor-deposited (CVD) diamond, diamondlike carbon, and cubic boron nitride films in sliding contact with CVD diamond in ultrahigh vacuum, dry nitrogen, humid air, and water are discussed. Furthermore, the actual and potential applications of the three different superhard coatings in the field of tribology technology, particularly for wear parts and tools, are reviewed.

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.

Synthesis of graphitic carbon nitride by reaction of melamine and uric acid

International Nuclear Information System (INIS)

Dante, Roberto C.; Martin-Ramos, Pablo; Correa-Guimaraes, Adriana; Martin-Gil, Jesus

2011-01-01

Highlights: → Graphitic carbon nitrides by CVD of melamine and uric acid on alumina. → The building blocks of carbon nitrides are heptazine nuclei. → Composite particles with alumina core and carbon nitride coating. - Abstract: Graphitic carbon nitrides were synthesized starting from melamine and uric acid. Uric acid was chosen because it thermally decomposes, and reacts with melamine by condensation at temperatures in the range of 400-600 deg. C. The reagents were mixed with alumina and subsequently the samples were treated in an oven under nitrogen flux. Alumina favored the deposition of the graphitic carbon nitrides layers on the exposed surface. This method can be assimilated to an in situ chemical vapor deposition (CVD). Infrared (IR) spectra, as well as X-ray diffraction (XRD) patterns, are in accordance with the formation of a graphitic carbon nitride with a structure based on heptazine blocks. These carbon nitrides exhibit poor crystallinity and a nanometric texture, as shown by transmission electron microscopy (TEM) analysis. The thermal degradation of the graphitic carbon nitride occurs through cyano group formation, and involves the bridging tertiary nitrogen and the bonded carbon, which belongs to the heptazine ring, causing the ring opening and the consequent network destruction as inferred by connecting the IR and X-ray photoelectron spectroscopy (XPS) results. This seems to be an easy and promising route to synthesize graphitic carbon nitrides. Our final material is a composite made of an alumina core covered by carbon nitride layers.

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

Multilayered and composite PVD-CVD coatings in cemented carbides manufacture

International Nuclear Information System (INIS)

Glushkov, V.N.; Anikeev, A.I.; Anikin, V.N.; Vereshchaka, A.S.

2001-01-01

Carbide cutting tools with wear-resistant coatings deposited by CVD process are widely employed in mechanical engineering to ensure a substantially longer service life of tool systems. However, the relatively high temperature and long time of the process make the substrate decarburise and, as a result, the bend strength and performance characteristics of a tool decrease. The present study suggests the problem of deteriorated strength of CVD-coated carbide tools be solved by the development of a technology that combines arc-PVD and CVD processes to deposit multilayered coatings of titanium and aluminium compounds. (author)

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.

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.

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.

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

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

Directory of Open Access Journals (Sweden)

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.

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

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)

High-speed deposition of titanium carbide coatings by laser-assisted metal–organic CVD

Energy Technology Data Exchange (ETDEWEB)

Gong, Yansheng [Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Tu, Rong, E-mail: turong@whut.edu.cn [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Goto, Takashi [Institute for Materials Research, Tohoku University, Aoba-ku, 2-1-1 Katahira, Sendai 980-8577 (Japan)

2013-08-01

Graphical abstract: - Highlights: • A semiconductor laser was first used to prepare wide-area LCVD-TiC{sub x} coatings. • The effect of laser power for the deposition of TiC{sub x} coatings was discussed. • TiC{sub x} coatings showed a columnar cross section and a dense surface texture. • TiC{sub x} coatings had a 1–4 order lower laser density than those of previous reports. • This study gives the possibility of LCVD applying on the preparation of TiC{sub x} coating. - Abstract: A semiconductor laser-assisted chemical vapor deposition (LCVD) of titanium carbide (TiC{sub x}) coatings on Al{sub 2}O{sub 3} substrate using tetrakis (diethylamido) titanium (TDEAT) and C{sub 2}H{sub 2} as source materials were investigated. The influences of laser power (P{sub L}) and pre-heating temperature (T{sub pre}) on the microstructure and deposition rate of TiC{sub x} coatings were examined. Single phase of TiC{sub x} coatings were obtained at P{sub L} = 100–200 W. TiC{sub x} coatings had a cauliflower-like surface and columnar cross section. TiC{sub x} coatings in the present study had the highest R{sub dep} (54 μm/h) at a relative low T{sub dep} than those of conventional CVD-TiC{sub x} coatings. The highest volume deposition rate (V{sub dep}) of TiC{sub x} coatings was about 4.7 × 10{sup −12} m{sup 3} s{sup −1}, which had 3–10{sup 5} times larger deposition area and 1–4 order lower laser density than those of previous LCVD using CO{sub 2}, Nd:YAG and argon ion laser.

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

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.

CVD boron nitride infiltration of fibrous structures: properties of low temprature deposits

International Nuclear Information System (INIS)

Gebhardt, J.J.

1973-01-01

The pyrolytic infiltration of boron nitride and silica fibrous structures with boron nitride was investigated using the thermal decomposition of B-trichloroborazole (TCB) to provide the matrix surrounding felted and 4-directional braided constructions. The deposition precursor was generated on a continuous basis by the reaction between boron trichloride and ammonium chloride in a fixed bed reactor under conditions of total conversion of the trichloride: 3BCl 3 + 3NH 4 Cl = B 3 N 3 H 3 Cl 3 + 9HCl. Deposition rates in boron nitride felt specimens varied between 8 and 28 μm/h, depending on the distance from the exterior surface at the minimum deposition temperature used (1100 0 C ). Infiltration of 4-directional silica braids was poorer because of clogging of the fiber bundle surfaces and access paths to voids in the weave. Deposits prepared at 1100 0 C and above were stable to moisture and consisted of glassy transparent materials which had no discernible x-ray diffraction pattern. Heat treatment of low temperature deposits in nitrogen at 1800 0 C caused significant growth of the crystallites and the emergence of x-ray patterns characteristic of hexagonal boron nitride. Heat treatment in vacuum caused changes in the infrared spectrum which could be correlated with mass analyses of the gases evolved. Loss of hydrogen with amines predominated to about 1500 0 C above which point the loss of nitrogen became significant. (14 figures) (U.S.)

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

Coating of carbon short fibers with thin ceramic layers by chemical vapor deposition

International Nuclear Information System (INIS)

Hackl, Gerrit; Gerhard, Helmut; Popovska, Nadejda

2006-01-01

Carbon short fiber bundles with a length of 6 mm were uniformly coated using specially designed, continuous chemical vapor deposition (CVD) equipment. Thin layers of titanium nitride, silicon nitride (SiC) and pyrolytic carbon (pyC) were deposited onto several kilograms of short fibers in this large scale CVD reactor. Thermo-gravimetric analyses and scanning electron microscopy investigations revealed layer thicknesses between 20 and 100 nm on the fibers. Raman spectra of pyC coated fibers show a change of structural order depending on the CVD process parameters. For the fibers coated with SiC, Raman investigations showed a deposition of amorphous SiC. The coated carbon short fibers will be applied as reinforcing material in composites with ceramic and metallic matrices

Industrial science and technology research and development project of university cooperative type in fiscal 2000. Report on achievements in semiconductor device manufacturing processes using Cat-CVD method (Semiconductor device manufacturing processes using Cat-CVD method); 2000 nendo daigaku renkeigata sangyo kagaku gijutsu kenkyu kaihatsu project. Cat-CVD ho ni yoru handotai device seizo process seika hokokusho (Cat-CVD ho ni yoru handotai device seizo process)

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

The catalytic chemical vapor deposition (Cat-CVD) method is a low-temperature thin film depositing technology that can achieve improvement in quality of semiconductor thin films and can perform inexpensive film deposition in a large area. The present project is composed of the basic research and development theme and the demonstrative research and development theme for the Cat-CVD method. This report summarizes the achievements in fiscal 2000 centering on the former theme. Discussions were given on the following five areas: 1) simulation on film thickness distribution in the Cat-CVD method, 2) life extension by preventing the catalyst converting into silicide and development of a catalyst integrated shear head, 3) vapor diagnosis in the film forming process by the Cat-CVD method using silane, hydrogen and ammonia, 4) a technology for high-speed deposition of hydrogenated amorphous silicon films for solar cells using the Cat-CVD method, and the low-temperature silicon oxide nitriding technology using heated catalysts, and 5) discussions on compatibility of transparent oxide electrode materials to the process of manufacturing thin-film silicon-based solar cells by using the Cat-CVD method. (NEDO)

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...

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°.

Spin transport in two-layer-CVD-hBN/graphene/hBN heterostructures

Science.gov (United States)

Gurram, M.; Omar, S.; Zihlmann, S.; Makk, P.; Li, Q. C.; Zhang, Y. F.; Schönenberger, C.; van Wees, B. J.

2018-01-01

We study room-temperature spin transport in graphene devices encapsulated between a layer-by-layer-stacked two-layer-thick chemical vapor deposition (CVD) grown hexagonal boron nitride (hBN) tunnel barrier, and a few-layer-thick exfoliated-hBN substrate. We find mobilities and spin-relaxation times comparable to that of SiO2 substrate-based graphene devices, and we obtain a similar order of magnitude of spin relaxation rates for both the Elliott-Yafet and D'Yakonov-Perel' mechanisms. The behavior of ferromagnet/two-layer-CVD-hBN/graphene/hBN contacts ranges from transparent to tunneling due to inhomogeneities in the CVD-hBN barriers. Surprisingly, we find both positive and negative spin polarizations for high-resistance two-layer-CVD-hBN barrier contacts with respect to the low-resistance contacts. Furthermore, we find that the differential spin-injection polarization of the high-resistance contacts can be modulated by dc bias from -0.3 to +0.3 V with no change in its sign, while its magnitude increases at higher negative bias. These features point to the distinctive spin-injection nature of the two-layer-CVD-hBN compared to the bilayer-exfoliated-hBN tunnel barriers.

Delaminated Transfer of CVD Graphene

Science.gov (United States)

Clavijo, Alexis; Mao, Jinhai; Tilak, Nikhil; Altvater, Michael; Andrei, Eva

Single layer graphene is commonly synthesized by dissociation of a carbonaceous gas at high temperatures in the presence of a metallic catalyst in a process known as Chemical Vapor Deposition or CVD. Although it is possible to achieve high quality graphene by CVD, the standard transfer technique of etching away the metallic catalyst is wasteful and jeopardizes the quality of the graphene film by contamination from etchants. Thus, development of a clean transfer technique and preservation of the parent substrate remain prominent hurdles to overcome. In this study, we employ a copper pretreatment technique and optimized parameters for growth of high quality single layer graphene at atmospheric pressure. We address the transfer challenge by utilizing the adhesive properties between a polymer film and graphene to achieve etchant-free transfer of graphene films from a copper substrate. Based on this concept we developed a technique for dry delamination and transferring of graphene to hexagonal boron nitride substrates, which produced high quality graphene films while at the same time preserving the integrity of the copper catalyst for reuse. DOE-FG02-99ER45742, Ronald E. McNair Postbaccalaureate Achievement Program.

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.

Industrial science and technology research and development project of university cooperative type in fiscal 2000. Report on achievements in semiconductor device manufacturing processes using Cat-CVD method (Development of technology to rationalize energy usage); 2000 nendo daigaku renkeigata sangyo kagaku gijutsu kenkyu kaihatsu project. Cat-CVD ho ni yoru handotai device seizo process seika hokokusho (energy shiyo gorika gijutsu kaihatsu)

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

The catalytic chemical vapor deposition (Cat-CVD) method is a low-temperature thin film depositing technology that can achieve improvement in quality of semiconductor thin films and can perform inexpensive film deposition in a large area. This paper summarizes the achievements in fiscal 2000 in the demonstrative research and development theme of the present project, centering on the following five areas: 1) discussions on application of the Cat-CVD method to the mass production process for gallium arsenide integrated circuits, 2) studies on the possibility to apply the Cat-CVD method to the process to fabricate nitrided silicon protective film for ferroelectric memory devices, 3) formation of nitrided silicon films for silicon integrated circuits by means of the Cat-CVD method, and development of a chamber cleaning technology, 4) fabrication of high-mobility poly-crystalline silicon thin film transistors formed by using the Cat-CVD method and large particle size poly-crystalline silicon films by using the catalytic chemical sputtering process, and 5) discussions on properties of amorphous silicon thin film transistors formed by using the Cat-CVD method and formation of large area films by using a catalyst integrated shower head. (NEDO)

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

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.

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...

Oxidation kinetics of CVD silicon carbide and silicon nitride

Science.gov (United States)

Fox, Dennis S.

1992-01-01

The long-term oxidation behavior of pure, monolithic CVD SiC and Si3N4 is studied, and the isothermal oxidation kinetics of these two materials are obtained for the case of 100 hrs at 1200-1500 C in flowing oxygen. Estimates are made of lifetimes at the various temperatures investigated. Parabolic rate constants for SiC are within an order of magnitude of shorter exposure time values reported in the literature. The resulting silica scales are in the form of cristobalite, with cracks visible after exposure. The oxidation protection afforded by silica for these materials is adequate for long service times under isothermal conditions in 1-atm dry oxygen.

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.

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.

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

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.

Ballistic Transport Exceeding 28 μm in CVD Grown Graphene.

Science.gov (United States)

Banszerus, Luca; Schmitz, Michael; Engels, Stephan; Goldsche, Matthias; Watanabe, Kenji; Taniguchi, Takashi; Beschoten, Bernd; Stampfer, Christoph

2016-02-10

We report on ballistic transport over more than 28 μm in graphene grown by chemical vapor deposition (CVD) that is fully encapsulated in hexagonal boron nitride. The structures are fabricated by an advanced dry van-der-Waals transfer method and exhibit carrier mobilities of up to three million cm(2)/(Vs). The ballistic nature of charge transport is probed by measuring the bend resistance in cross- and square-shaped devices. Temperature-dependent measurements furthermore prove that ballistic transport is maintained exceeding 1 μm up to 200 K.

Alkaline fuel cell with nitride membrane

Science.gov (United States)

Sun, Shen-Huei; Pilaski, Moritz; Wartmann, Jens; Letzkus, Florian; Funke, Benedikt; Dura, Georg; Heinzel, Angelika

2017-06-01

The aim of this work is to fabricate patterned nitride membranes with Si-MEMS-technology as a platform to build up new membrane-electrode-assemblies (MEA) for alkaline fuel cell applications. Two 6-inch wafer processes based on chemical vapor deposition (CVD) were developed for the fabrication of separated nitride membranes with a nitride thickness up to 1 μm. The mechanical stability of the perforated nitride membrane has been adjusted in both processes either by embedding of subsequent ion implantation step or by optimizing the deposition process parameters. A nearly 100% yield of separated membranes of each deposition process was achieved with layer thickness from 150 nm to 1 μm and micro-channel pattern width of 1μm at a pitch of 3 μm. The process for membrane coating with electrolyte materials could be verified to build up MEA. Uniform membrane coating with channel filling was achieved after the optimization of speed controlled dip-coating method and the selection of dimethylsulfoxide (DMSO) as electrolyte solvent. Finally, silver as conductive material was defined for printing a conductive layer onto the MEA by Ink-Technology. With the established IR-thermography setup, characterizations of MEAs in terms of catalytic conversion were performed successfully. The results of this work show promise for build up a platform on wafer-level for high throughput experiments.

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.

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.

CVD diamond deposition onto dental burs

International Nuclear Information System (INIS)

Ali, N.; Sein, H.

2001-01-01

A hot-filament chemical vapor deposition (HFCVD) system has been modified to enable non-planar substrates, such as metallic wires and dental burs, to be uniformly coated with thin polycrystalline diamond films. Initially, diamond deposition was carried out on titanium and tantalum wires in order to test and optimize the system. High growth rates of the order of approx. 8 /hr were obtained when depositing diamond on titanium wires using the vertical filament arrangement. However, lower growth rates of the order of 4-5meu m/hr were obtained with diamond deposition on tantalum wires. To extend the work towards a practical biomedical application tungsten carbide dental burs were coated with diamond films. The as-grown films were found to be polycrystalline and uniform over the cutting tip. Finally, the costs relating to diamond CVD onto dental burs have been presented in this paper. The costs relating to coating different number of burs at a time and the effect of film thickness on costs have been included in this investigation. (author)

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

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.

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

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.

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.

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.

CVD diamond coatings on titanium : Characterisation by XRD techniques

Energy Technology Data Exchange (ETDEWEB)

Cappuccio, G [CNR, Frascati, Rome (Italy). Istituto di Strutturistica Chimica; [INFN-LNF, Frascati, Rome (Italy). Laboratorio Dafne Luce

1996-09-01

Here, the authors report an analysis carried out on diamond coatings on titanium substrates to show the potentially of x-ray diffraction techniques in the structural characterisation both of diamond thin films and of the other phases (TiC and TiH{sub 2}) present in the interfacial layer. It should be noted that the composition and microstructure of the interface layers strongly affect the characteristics of the diamond films, particularly adhesion, which is one of the most important elements determining the final quality of the coating.

Facility for continuous CVD coating of ceramic fibers

International Nuclear Information System (INIS)

Moore, A.W.

1992-01-01

The development of new and improved ceramic fibers has spurred the development and application of ceramic composites with improved strength, strength/weight ratio, toughness, and durability at increasingly high temperatures. For many systems, the ceramic fibers can be used without modification because their properties are adequate for the chosen application. However, in order to take maximum advantage of the fiber properties, it is often necessary to coat the ceramic fibers with materials of different composition and properties. Examples include (1) boron nitride coatings on a ceramic fiber, such as Nicalon silicon carbide, to prevent reaction with the ceramic matrix during fabrication and to enhance fiber pullout and increase toughness when the ceramic composite is subjected to stress; (2) boron nitride coatings on ceramic yarns, such as Nicalon for use as thermal insulation panels in an aerodynamic environment, to reduce abrasion of the Nicalon and to inhibit the oxidation of free carbon contained within the Nicalon; and (3) ceramic coatings on carbon yarns and carbon-carbon composites to permit use of these high-strength, high-temperature materials in oxidizing environments at very high temperatures. This paper describes a pilot-plant-sized CVD facility for continuous coating of ceramic fibers and some of the results obtained so far with this equipment

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.

Adhesion and size dependent friction anisotropy in boron nitride nanotubes

International Nuclear Information System (INIS)

Chiu, Hsiang-Chih; Riedo, Elisa; Dogan, Sedat; Volkmann, Mirjam; Klinke, Christian

2012-01-01

The frictional properties of individual multiwalled boron nitride nanotubes (BN-NTs) synthesized by chemical vapour deposition (CVD) and deposited on a silicon substrate are investigated using an atomic force microscope tip sliding along (longitudinal sliding) and across (transverse sliding) the tube’s principal axis. Because of the tube’s transverse deformations during the tip sliding, a larger friction coefficient is found for the transverse sliding as compared to the longitudinal sliding. Here, we show that the friction anisotropy in BN-NTs, defined as the ratio between transverse and longitudinal friction forces per unit area, increases with the nanotube–substrate contact area, estimated to be proportional to (L NT R NT ) 1/2 , where L NT and R NT are the length and the radius of the nanotube, respectively. Larger contact area denotes stronger surface adhesion, resulting in a longitudinal friction coefficient closer to the value expected in the absence of transverse deformations. Compared to carbon nanotubes (C-NTs), BN-NTs display a friction coefficient in each sliding direction with intermediate values between CVD and arc discharge C-NTs. CVD BN-NTs with improved tribological properties and higher oxidation temperature might be a better candidate than CVD C-NTs for applications in extreme environments. (paper)

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%.

{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.

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

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.

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.))

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)

Low-temperature CVD of iron, cobalt, and nickel nitride thin films from bis[di(tert-butyl)amido]metal(II) precursors and ammonia

International Nuclear Information System (INIS)

Cloud, Andrew N.; Abelson, John R.; Davis, Luke M.; Girolami, Gregory S.

2014-01-01

Thin films of late transition metal nitrides (where the metal is iron, cobalt, or nickel) are grown by low-pressure metalorganic chemical vapor deposition from bis[di(tert-butyl)amido]metal(II) precursors and ammonia. These metal nitrides are known to have useful mechanical and magnetic properties, but there are few thin film growth techniques to produce them based on a single precursor family. The authors report the deposition of metal nitride thin films below 300 °C from three recently synthesized M[N(t-Bu) 2 ] 2 precursors, where M = Fe, Co, and Ni, with growth onset as low as room temperature. Metal-rich phases are obtained with constant nitrogen content from growth onset to 200 °C over a range of feedstock partial pressures. Carbon contamination in the films is minimal for iron and cobalt nitride, but similar to the nitrogen concentration for nickel nitride. X-ray photoelectron spectroscopy indicates that the incorporated nitrogen is present as metal nitride, even for films grown at the reaction onset temperature. Deposition rates of up to 18 nm/min are observed. The film morphologies, growth rates, and compositions are consistent with a gas-phase transamination reaction that produces precursor species with high sticking coefficients and low surface mobilities

Boron nitride coated uranium dioxide and uranium dioxide-gadolinium oxide fuels

Energy Technology Data Exchange (ETDEWEB)

Gunduz, G [Department of Chemical Engineering, Middle East Technical Univ., Ankara (Turkey); Uslu, I; Tore, C; Tanker, E [Turkiye Atom Enerjisi Kurumu, Ankara (Turkey)

1997-08-01

Pure Urania and Urania-gadolinia (5 and 10%) fuels were produced by sol-gel technique. The sintered fuel pellets were then coated with boron nitride (BN). This is achieved through chemical vapor deposition (CVD) using boron trichloride and ammonia. The coated samples were sintered at 1600 K. The analyses under scanning electron microscope (SEM) showed a variety of BN structures, mainly platelike and rodlike structures were observed. Burnup calculations by using WIMSD4 showed that BN coated and gadolinia containing fuels have larger burnups than other fuels. The calculations were repeated at different pitch distances. The change of the radius of the fuel pellet or the moderator/fuel ratio showed that BN coated fuel gives the highest burnups at the present design values of a PWR. Key words: burnable absorber, boron nitride, gadolinia, CVT, nuclear fuel. (author). 32 refs, 14 figs.

Boron nitride coated uranium dioxide and uranium dioxide-gadolinium oxide fuels

International Nuclear Information System (INIS)

Gunduz, G.; Uslu, I.; Tore, C.; Tanker, E.

1997-01-01

Pure Urania and Urania-gadolinia (5 and 10%) fuels were produced by sol-gel technique. The sintered fuel pellets were then coated with boron nitride (BN). This is achieved through chemical vapor deposition (CVD) using boron trichloride and ammonia. The coated samples were sintered at 1600 K. The analyses under scanning electron microscope (SEM) showed a variety of BN structures, mainly platelike and rodlike structures were observed. Burnup calculations by using WIMSD4 showed that BN coated and gadolinia containing fuels have larger burnups than other fuels. The calculations were repeated at different pitch distances. The change of the radius of the fuel pellet or the moderator/fuel ratio showed that BN coated fuel gives the highest burnups at the present design values of a PWR. Key words: burnable absorber, boron nitride, gadolinia, CVT, nuclear fuel. (author). 32 refs, 14 figs

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

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.

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

CVD growth of graphene under exfoliated hexagonal boron nitride for vertical hybrid structures

Energy Technology Data Exchange (ETDEWEB)

Wang, Min [SKKU Advanced Institute of Nanotechnology (SAINT) (Korea, Republic of); Center for Human Interface Nanotechnology (HINT) (Korea, Republic of); Jang, Sung Kyu [SKKU Advanced Institute of Nanotechnology (SAINT) (Korea, Republic of); Song, Young Jae [SKKU Advanced Institute of Nanotechnology (SAINT) (Korea, Republic of); Department of Physics, Sungkyunkwan University (SKKU), Suwon 440-746 (Korea, Republic of); Lee, Sungjoo, E-mail: leesj@skku.edu [SKKU Advanced Institute of Nanotechnology (SAINT) (Korea, Republic of); Center for Human Interface Nanotechnology (HINT) (Korea, Republic of); College of Information and Communication Engineering, Sungkyunkwan University (SKKU), Suwon 440-746 (Korea, Republic of)

2015-01-15

Graphical abstract: We have demonstrated a novel yet simple method for fabricating graphene-based vertical hybrid structures by performing the CVD growth of graphene at an h-BN/Cu interface. Our systematic Raman measurements combined with plasma etching process indicate that a graphene film is grown under exfoliated h-BN rather than on its top surface, and that an h-BN/graphene vertical hybrid structure has been fabricated. Electrical transport measurements of this h-BN/graphene, transferred on SiO2, show the carrier mobility up to approximately 2250 cm{sup 2} V{sup −1} s{sup −1}. The developed method would enable the exploration of the possibility of novel hybrid structure integration with two-dimensional material systems. - Abstract: We have demonstrated a novel yet simple method for fabricating graphene-based vertical hybrid structures by performing the CVD growth of graphene at an h-BN/Cu interface. Our systematic Raman measurements combined with plasma etching process indicate that a graphene film is grown under exfoliated h-BN rather than on its top surface, and that an h-BN/graphene vertical hybrid structure has been fabricated. Electrical transport measurements of this h-BN/graphene, transferred on SiO{sub 2}, show the carrier mobility up to approximately 2250 cm{sup 2} V{sup −1} s{sup −1}. The developed method would enable the exploration of the possibility of novel hybrid structure integration with two-dimensional material systems.

CVD growth of graphene under exfoliated hexagonal boron nitride for vertical hybrid structures

International Nuclear Information System (INIS)

Wang, Min; Jang, Sung Kyu; Song, Young Jae; Lee, Sungjoo

2015-01-01

Graphical abstract: We have demonstrated a novel yet simple method for fabricating graphene-based vertical hybrid structures by performing the CVD growth of graphene at an h-BN/Cu interface. Our systematic Raman measurements combined with plasma etching process indicate that a graphene film is grown under exfoliated h-BN rather than on its top surface, and that an h-BN/graphene vertical hybrid structure has been fabricated. Electrical transport measurements of this h-BN/graphene, transferred on SiO2, show the carrier mobility up to approximately 2250 cm 2 V −1 s −1 . The developed method would enable the exploration of the possibility of novel hybrid structure integration with two-dimensional material systems. - Abstract: We have demonstrated a novel yet simple method for fabricating graphene-based vertical hybrid structures by performing the CVD growth of graphene at an h-BN/Cu interface. Our systematic Raman measurements combined with plasma etching process indicate that a graphene film is grown under exfoliated h-BN rather than on its top surface, and that an h-BN/graphene vertical hybrid structure has been fabricated. Electrical transport measurements of this h-BN/graphene, transferred on SiO 2 , show the carrier mobility up to approximately 2250 cm 2 V −1 s −1 . The developed method would enable the exploration of the possibility of novel hybrid structure integration with two-dimensional material systems

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

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)

Oxidation Protection of Porous Reaction-Bonded Silicon Nitride

Science.gov (United States)

Fox, D. S.

1994-01-01

Oxidation kinetics of both as-fabricated and coated reaction-bonded silicon nitride (RBSN) were studied at 900 and 1000 C with thermogravimetry. Uncoated RBSN exhibited internal oxidation and parabolic kinetics. An amorphous Si-C-O coating provided the greatest degree of protection to oxygen, with a small linear weight loss observed. Linear weight gains were measured on samples with an amorphous Si-N-C coating. Chemically vapor deposited (CVD) Si3N4 coated RBSN exhibited parabolic kinetics, and the coating cracked severely. A continuous-SiC-fiber-reinforced RBSN composite was also coated with the Si-C-O material, but no substantial oxidation protection was observed.

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.

Rebar graphene from functionalized boron nitride nanotubes.

Science.gov (United States)

Li, Yilun; Peng, Zhiwei; Larios, Eduardo; Wang, Gunuk; Lin, Jian; Yan, Zheng; Ruiz-Zepeda, Francisco; José-Yacamán, Miguel; Tour, James M

2015-01-27

The synthesis of rebar graphene on Cu substrates is described using functionalized boron nitride nanotubes (BNNTs) that were annealed or subjected to chemical vapor deposition (CVD) growth of graphene. Characterization shows that the BNNTs partially unzip and form a reinforcing bar (rebar) network within the graphene layer that enhances the mechanical strength through covalent bonds. The rebar graphene is transferrable to other substrates without polymer assistance. The optical transmittance and conductivity of the hybrid rebar graphene film was tested, and a field effect transistor was fabricated to explore its electrical properties. This method of synthesizing 2D hybrid graphene/BN structures should enable the hybridization of various 1D nanotube and 2D layered structures with enhanced mechanical properties.

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.

Spintronics with graphene-hexagonal boron nitride van der Waals heterostructures

International Nuclear Information System (INIS)

Kamalakar, M. Venkata; Dankert, André; Bergsten, Johan; Ive, Tommy; Dash, Saroj P.

2014-01-01

Hexagonal boron nitride (h-BN) is a large bandgap insulating isomorph of graphene, ideal for atomically thin tunnel barrier applications. In this letter, we demonstrate large area chemical vapor deposited (CVD) h-BN as a promising spin tunnel barrier in graphene spin transport devices. In such structures, the ferromagnetic tunnel contacts with h-BN barrier are found to show robust tunneling characteristics over a large scale with resistances in the favorable range for efficient spin injection into graphene. The non-local spin transport and precession experiments reveal spin lifetime ≈500 ps and spin diffusion length ≈1.6 μm in graphene with tunnel spin polarization ≈11% at 100 K. The electrical and spin transport measurements at different injection bias current and gate voltages confirm tunnel spin injection through h-BN barrier. These results open up possibilities for implementation of large area CVD h-BN in spintronic technologies

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.

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.

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

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....

Viscoelastic sliding and diffusive relaxation along grain boundaries in polycrystalline boron nitride

International Nuclear Information System (INIS)

Pezzotti, G.; Nishida, Toshihiko; Kleebe, H.J.; Ota, Kenichi

1997-01-01

Dense hexagonal boron nitride (BN) materials were prepared via two different processing routes: (1) hot-pressing with the addition of a Ca/B-containing glass and (2) chemical vapor deposition (CVD). The resulting microstructure of both materials was studied by scanning and transmission electron microscopy. While the hot-pressed BN material shows, apart from large BN matrix grains, an inhomogeneous distribution of residual glass at room temperature, the CVD deposition yields a homogeneous fine grained microstructure with no amorphous residue detectable. Internal-friction experiments were performed to study the micromechanical response of the materials when exposed to high temperatures. The CVD material revealed no relaxation peak during testing up to 2,300 C, while the glass-doped sample showed a pronounced relaxation peak at a peak-top temperature of about 600 C. This temperature corresponds to the softening temperature known for bulk Ca/B-glasses and it is, therefore, concluded that the glass homogeneously wets the BN grains at elevated temperatures. The results presented are seen as the first clear evidence that the internal friction peak monitored for various glass-containing ceramics is indeed related to a viscous sliding process along grain boundaries

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)

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)

Fabrication of graphene/titanium carbide nanorod arrays for chemical sensor application

Energy Technology Data Exchange (ETDEWEB)

Fu, Chong [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China); Li, Mingji, E-mail: limingji@163.com [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China); Li, Hongji, E-mail: hongjili@yeah.net [Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion, School of Chemistry & Chemical Engineering, Tianjin University of Technology, Tianjin 300384 (China); Li, Cuiping; Qu, Changqing; Yang, Baohe [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China)

2017-03-01

Vertically stacked graphene nanosheet/titanium carbide nanorod array/titanium (graphene/TiC nanorod array) wires were fabricated using a direct current arc plasma jet chemical vapor deposition (DC arc plasma jet CVD) method. The graphene/TiC nanorod arrays were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction spectroscopy. The TiO{sub 2} nanotube array was reduced to the TiC nanorod array, and using those TiC nanorods as nucleation sites, the vertical graphene layer was formed on the TiC nanorod surface. The multi-target response mechanisms of the graphene/TiC nanorod array were investigated for ascorbic acid (AA), dopamine (DA), uric acid (UA), and hydrochlorothiazide (HCTZ). The vertically stacked graphene sheets facilitated the electron transfer and reactant transport with a unique porous surface, high surface area, and high electron transport network of CVD graphene sheets. The TiC nanorod array facilitated the electron transfer and firmly held the graphene layer. Thus, the graphene/TiC nanorod arrays could simultaneously respond to trace biomarkers and antihypertensive drugs. - Highlights: • Vertical graphene sheets were prepared with Ti as the catalyst via a CVD method. • TiO{sub 2} nanotubes were key transition layers in the formation of the TiC nanorods. • Vertical growth mechanism of graphene products was discussed. • Biomolecules were detected to be a chemical sensor. • Response mechanism for analytes at the graphene/TiC nanorod array was discussed.

Fabrication of graphene/titanium carbide nanorod arrays for chemical sensor application

International Nuclear Information System (INIS)

Fu, Chong; Li, Mingji; Li, Hongji; Li, Cuiping; Qu, Changqing; Yang, Baohe

2017-01-01

Vertically stacked graphene nanosheet/titanium carbide nanorod array/titanium (graphene/TiC nanorod array) wires were fabricated using a direct current arc plasma jet chemical vapor deposition (DC arc plasma jet CVD) method. The graphene/TiC nanorod arrays were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction spectroscopy. The TiO 2 nanotube array was reduced to the TiC nanorod array, and using those TiC nanorods as nucleation sites, the vertical graphene layer was formed on the TiC nanorod surface. The multi-target response mechanisms of the graphene/TiC nanorod array were investigated for ascorbic acid (AA), dopamine (DA), uric acid (UA), and hydrochlorothiazide (HCTZ). The vertically stacked graphene sheets facilitated the electron transfer and reactant transport with a unique porous surface, high surface area, and high electron transport network of CVD graphene sheets. The TiC nanorod array facilitated the electron transfer and firmly held the graphene layer. Thus, the graphene/TiC nanorod arrays could simultaneously respond to trace biomarkers and antihypertensive drugs. - Highlights: • Vertical graphene sheets were prepared with Ti as the catalyst via a CVD method. • TiO 2 nanotubes were key transition layers in the formation of the TiC nanorods. • Vertical growth mechanism of graphene products was discussed. • Biomolecules were detected to be a chemical sensor. • Response mechanism for analytes at the graphene/TiC nanorod array was discussed.

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

CVD - main concepts, applications and restrictions

International Nuclear Information System (INIS)

Bliznakovska, B.; Milosevski, M.; Krawczynski, S.; Meixner, C.; Koetter, H.R.

1993-01-01

Despite of the fact that the existing literature covering the last two decades is plentiful with data related to CVD, this document is an attempt to provide to a reader a concise information about the nature of CVD technique at production of technologically important materials as well as to point at special references. The text is devided into three separate sections. The first section, The Main Features of CVD, is intended to give a complete comprehensive picture of the CVD technique through process description and characterization. The basic principles of thermodynamics, CVD chemical reactions classification, CVD chemical kinetics aspects and physics of CVD (with particular attention on the gas-flow phenomena) are included. As an additional aspect, in CVD unavoidable aspect however, the role of the coating/substrate compatibility on the overall process was outlined. The second section, CVD Equipment, concerns on the pecularities of the complete CVD unit pointing out the individual significances of the separate parts, i.e. pumping system, reactor chamber, control system. The aim of this section is to create to a reader a basic understanding of the arising problems but connected to be actual CVD performance. As a final goal of this review the reader's attention is turned upon the CVD applications for production of an up-to-date important class of coatings such as multilayer coatings. (orig.)

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

Synthesis and characterization of boron nitrides nanotubes

International Nuclear Information System (INIS)

Ferreira, T.H.; Sousa, E.M.B.

2010-01-01

This paper presents a new synthesis for the production of boron nitride nanotubes (BNNT) from boron powder, ammonium nitrate and hematite tube furnace CVD method. The samples were subjected to some characterization techniques as infrared spectroscopy, thermal analysis, X-ray diffraction and scanning electron microscopy and transmission. By analyzing the results can explain the chemical reactions involved in the process and confirm the formation of BNNT with several layers and about 30 nanometers in diameter. Due to excellent mechanical properties and its chemical and thermal stability this material is promising for various applications. However, BNNT has received much less attention than carbon nanotubes, it is because of great difficulty to synthesize appreciable quantities from the techniques currently known, and this is one of the main reasons this work.(author)

Interlayer utilization (including metal borides) for subsequent deposition of NSD films via microwave plasma CVD on 316 and 440C stainless steels

Science.gov (United States)

Ballinger, Jared

Diamond thin films have promising applications in numerous fields due to the extreme properties of diamonds in conjunction with the surface enhancement of thin films. Biomedical applications are numerous including temporary implants and various dental and surgical instruments. The unique combination of properties offered by nanostructured diamond films that make it such an attractive surface coating include extreme hardness, low obtainable surface roughness, excellent thermal conductivity, and chemical inertness. Regrettably, numerous problems exist when attempting to coat stainless steel with diamond generating a readily delaminated film: outward diffusion of iron to the surface, inward diffusion of carbon limiting necessary surface carbon precursor, and the mismatch between the coefficients of thermal expansion yielding substantial residual stress. While some exotic methods have been attempted to overcome these hindrances, the most common approach is the use of an intermediate layer between the stainless steel substrate and the diamond thin film. In this research, both 316 stainless steel disks and 440C stainless steel ball bearings were tested with interlayers including discrete coatings and graded, diffusion-based surface enhancements. Titanium nitride and thermochemical diffusion boride interlayers were both examined for their effectiveness at allowing for the growth of continuous and adherent diamond films. Titanium nitride interlayers were deposited by cathodic arc vacuum deposition on 440C bearings. Lower temperature diamond processing resulted in improved surface coverage after cooling, but ultimately, both continuity and adhesion of the nanostructured diamond films were unacceptable. The ability to grow quality diamond films on TiN interlayers is in agreement with previous work on iron and low alloy steel substrates, and the similarly seen inadequate adhesion strength is partially a consequence of the lacking establishment of an interfacial carbide phase

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

Directory of Open Access Journals (Sweden)

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

Microstructure and spectroscopy studies on cubic boron nitride synthesized under high-pressure conditions

International Nuclear Information System (INIS)

Nistor, L C; Nistor, S V; Dinca, G; Georgeoni, P; Landuyt, J van; Manfredotti, C; Vittone, E

2002-01-01

High-resolution electron microscopy (HREM) studies of the microstructure and specific defects in hexagonal boron nitride (h-BN) precursors and cubic boron nitride (c-BN) crystals made under high-pressure high-temperature conditions revealed the presence of half-nanotubes at the edges of the h-BN particles. Their sp 3 bonding tendency could strongly influence the nucleation rates of c-BN. The atomic resolution at extended dislocations was insufficient to allow us to determine the stacking fault energy in the c-BN crystals. Its mean value of 191 pm, 15 mJ m -2 is of the same order of magnitude as that of diamond. High-frequency (94 GHz) electron paramagnetic resonance studies on c-BN single crystals have produced new data on the D1 centres associated with the boron species. Ion-beam-induced luminescence measurements have indicated that c-BN is a very interesting luminescent material, which is characterized by four luminescence bands and exhibits a better resistance to ionizing radiation than CVD diamond

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.

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)

Experimental studies of N~+ implantation into CVD diamond thin films

Institute of Scientific and Technical Information of China (English)

辛火平; 林成鲁; 王建新; 邹世昌; 石晓红; 林梓鑫; 周祖尧; 刘祖刚

1997-01-01

The effects of N+ implantation under various conditions on CVD diamond films were analyzed with Raman spectroscopy, four-point probe method, X-ray diffraction (XRD), Rutherford backseattering spectroscopy (RBS), ultraviolet photoluminescence spectroscopy (UV-PL), Fourier transformation infrared absorption spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results show that the N+ implantation doping without any graphitization has been successfully realized when 100 keV N+ ions at a dosage of 2 × 1016 cm-2 were implanted into diamond films at 550℃ . UV-PL spectra indicate that the implanted N+ ions formed an electrically inactive deep-level impurity in diamond films. So the sheet resistance of the sample after N+ implantation changed little. Carbon nitride containing C≡N covalent bond has been successfully synthesized by 100 keV, 1.2×1018 N/cm2 N+ implantation into diamond films. Most of the implanted N+ ions formed C≡N covalent bonds with C atoms. The others were free state nitroge

Diffusion and adhesion properties of Cu films on polyimide substrates

International Nuclear Information System (INIS)

Liang, T.X.; Liu, Y.Q.; Fu, Z.Q.; Luo, T.Y.; Zhang, K.Y.

2005-01-01

Copper thin films were prepared on polyimide (PI) substrates by physical vapor deposition (PVD) and chemical vapor deposition (CVD). Titanium nitride (TiN) diffusion barrier layers were deposited between the copper films and the PI substrates by PVD. Auger electron spectroscopy compositional depth profile showed that TiN barrier layer was very effective in preventing copper diffusion into PI substrate even after the Cu/TiN/PI samples were annealed at 300 deg. C for 5 h. For the as-deposited CVD-Cu/PI, CVD-Cu/TiN/PI, and as-deposited PVD-Cu/PI samples, the residual stress in Cu films was very small. Relatively larger residual stress existed in Cu films for PVD-Cu/TiN/PI samples. For PVD-Cu/TiN/PI samples, annealing can increase the peeling strength to the level observed without a diffusion barrier. The adhesion improvement of Cu films by annealing treatment can be attributed to lowering of the residual tensile stress in Cu films

boron nitride coating of uranium dioxide and uranium dioxide-gadolinium oxide fuels by chemical precipitation method

International Nuclear Information System (INIS)

Uslu, I.; Tanker, E.; Guenduez, G.

1997-01-01

In this research pure urania and urania-gadolinia (5 and 10 %) fuels were coated with boron nitride (BN). This is achieved through chemical vapor deposition (CVD) using boron tricloride BCl 3 ) and ammonia (NH 3 ) at 600 C.Boron tricloride and ammonia are carried to tubular furnace using hydrogen as carrier gas. The coated samples were sintered at 1600 K. The properties of the coated samples were observed using BET surface area analysis, infrared spectra (IR), X-Ray Diffraction and Scanning Electron Microscope (SEM) techniques

[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.

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

Microstructure and spectroscopy studies on cubic boron nitride synthesized under high-pressure conditions

Energy Technology Data Exchange (ETDEWEB)

Nistor, L C [National Institute for Materials Physics, Bucharest (Romania); Nistor, S V [National Institute for Materials Physics, Bucharest (Romania); Dinca, G [Dacia Synthetic Diamonds Factory, Bucharest (Romania); Georgeoni, P [Dacia Synthetic Diamonds Factory, Bucharest (Romania); Landuyt, J van [University of Antwerpen - RUCA, EMAT, Antwerpen (Belgium); Manfredotti, C [Experimental Physics Department, University of Turin, Turin (Italy); Vittone, E [Experimental Physics Department, University of Turin, Turin (Italy)

2002-11-11

High-resolution electron microscopy (HREM) studies of the microstructure and specific defects in hexagonal boron nitride (h-BN) precursors and cubic boron nitride (c-BN) crystals made under high-pressure high-temperature conditions revealed the presence of half-nanotubes at the edges of the h-BN particles. Their sp{sup 3} bonding tendency could strongly influence the nucleation rates of c-BN. The atomic resolution at extended dislocations was insufficient to allow us to determine the stacking fault energy in the c-BN crystals. Its mean value of 191 pm, 15 mJ m{sup -2} is of the same order of magnitude as that of diamond. High-frequency (94 GHz) electron paramagnetic resonance studies on c-BN single crystals have produced new data on the D1 centres associated with the boron species. Ion-beam-induced luminescence measurements have indicated that c-BN is a very interesting luminescent material, which is characterized by four luminescence bands and exhibits a better resistance to ionizing radiation than CVD diamond.

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.

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.

Wear Mechanism of Chemical Vapor Deposition (CVD) Carbide Insert in Orthogonal Cutting Ti-6Al-4V ELI at High Cutting Speed

International Nuclear Information System (INIS)

Gusri, A. I.; Che Hassan, C. H.; Jaharah, A. G.

2011-01-01

The performance of Chemical Vapor Deposition (CVD) carbide insert with ISO designation of CCMT 12 04 04 LF, when turning titanium alloys was investigated. There were four layers of coating materials for this insert i.e.TiN-Al2O3-TiCN-TiN. The insert performance was evaluated based on the insert's edge resistant towards the machining parameters used at high cutting speed range of machining Ti-6Al-4V ELI. Detailed study on the wear mechanism at the cutting edge of CVD carbide tools was carried out at cutting speed of 55-95 m/min, feed rate of 0.15-0.35 mm/rev and depth of cut of 0.10-0.20 mm. Wear mechanisms such as abrasive and adhesive were observed on the flank face. Crater wear due to diffusion was also observed on the rake race. The abrasive wear occurred more at nose radius and the fracture on tool were found at the feed rate of 0.35 mm/rev and the depth of cut of 0.20 mm. The adhesion wear takes place after the removal of the coating or coating delaminating. Therefore, adhesion or welding of titanium alloy onto the flank and rake faces demonstrates a strong bond at the workpiece-tool interface.

Enhanced Tunnel Spin Injection into Graphene using Chemical Vapor Deposited Hexagonal Boron Nitride

Science.gov (United States)

Kamalakar, M. Venkata; Dankert, André; Bergsten, Johan; Ive, Tommy; Dash, Saroj P.

2014-01-01

The van der Waals heterostructures of two-dimensional (2D) atomic crystals constitute a new paradigm in nanoscience. Hybrid devices of graphene with insulating 2D hexagonal boron nitride (h-BN) have emerged as promising nanoelectronic architectures through demonstrations of ultrahigh electron mobilities and charge-based tunnel transistors. Here, we expand the functional horizon of such 2D materials demonstrating the quantum tunneling of spin polarized electrons through atomic planes of CVD grown h-BN. We report excellent tunneling behavior of h-BN layers together with tunnel spin injection and transport in graphene using ferromagnet/h-BN contacts. Employing h-BN tunnel contacts, we observe enhancements in both spin signal amplitude and lifetime by an order of magnitude. We demonstrate spin transport and precession over micrometer-scale distances with spin lifetime up to 0.46 nanosecond. Our results and complementary magnetoresistance calculations illustrate that CVD h-BN tunnel barrier provides a reliable, reproducible and alternative approach to address the conductivity mismatch problem for spin injection into graphene. PMID:25156685

The growth of GaN films by alternate source gas supply hot-mesh CVD method

Energy Technology Data Exchange (ETDEWEB)

Komae, Yasuaki; Saitou, Takeshi [Nagaoka University of Technology, Nagaoka 940-2188 (Japan); Suemitsu, Maki; Ito, Takashi [Center of Interdisciplinary Research, Tohoku University, Sendai 980-8578 (Japan); Endoh, Tetsuo [Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Nakazawa, Hideki [Faculty of Science and Technology, Hirosaki University, Hirosaki 036-8561 (Japan); Narita, Yuzuru [Faculty of Engineering, Yamagata University, Yonezawa 992-8510 (Japan); Takata, Masasuke; Akahane, Tadashi [Nagaoka University of Technology, Nagaoka 940-2188 (Japan); Yasui, Kanji, E-mail: kyasui@vos.nagaokaut.ac.j [Nagaoka University of Technology, Nagaoka 940-2188 (Japan)

2009-04-30

Gallium nitride (GaN) films and Aluminium nitride (AlN) layers were deposited on SiC/Si (111) substrates by an alternating source gas supply or an intermittent supply of a source gas such as ammonia (NH{sub 3}), trimethylgallium (TMG) or trimethylaluminum (TMA) in a hot-mesh chemical vapor deposition (CVD) apparatus. The AlN layer was deposited as a buffer layer using NH{sub 3} and TMA on a SiC layer grown by carbonization on Si substrates using propane (C{sub 3}H{sub 8}). GaN films were grown on an AlN layer by a reaction between NH{sub x} radicals generated on a ruthenium (Ru) coated tungsten (W)-mesh and TMG molecules. An alternating source gas supply or an intermittent supply of one of the source gases during the film growth are expected to be effective for the suppression of gas phase reactions and for the enhancement of precursor migration on the substrate surface. By the intermittent supply of alkylmetal gas only during the growth of the AlN layer, the defect generation in the GaN films was reduced. GaN film growth by intermittent supply on an AlN buffer layer, however, did not lead to the improvement of the film quality.

CVD diamond substrates for electronic devices

International Nuclear Information System (INIS)

Holzer, H.

1996-03-01

In this study the applicability of chemical vapor deposition (CVD) diamond as a material for heat spreaders was investigated. Economical evaluations on the production of heat spreaders were also performed. For the diamond synthesis the hot-filament and microwave method were used respectively. The deposition parameters were varied in a way that free standing diamond layers with a thickness of 80 to 750 microns and different qualities were obtained. The influence of the deposition parameters on the relevant film properties was investigated and discussed. With both the hot-filament and microwave method it was possible to deposit diamond layers having a thermal conductivity exceeding 1200 W/mK and therefore to reach the quality level for commercial uses. The electrical resistivity was greater than 10 12 Ωcm. The investigation of the optical properties was done by Raman-, IR- and cathodoluminescence spectroscopy. Because of future applications of diamond-aluminium nitride composites as highly efficient heat spreaders diamond deposition an AIN was investigated. An improved substrate pretreatment prior to diamond deposition showed promising results for better performance of such composite heat spreaders. Both free standing layers and diamond-AIN composites could be cut by a CO2 Laser in Order to get an exact size geometry. A reduction of the diamond surface roughness was achieved by etching with manganese powder or cerium. (author)

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.

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. .

CVD-graphene for low equivalent series resistance in rGO/CVD-graphene/Ni-based supercapacitors

Science.gov (United States)

Kwon, Young Hwi; Kumar, Sunil; Bae, Joonho; Seo, Yongho

2018-05-01

Reduced equivalent series resistance (ESR) is necessary, particularly at a high current density, for high performance supercapacitors, and the interface resistance between the current collector and electrode material is one of the main components of ESR. In this report, we have optimized chemical vapor deposition-grown graphene (CVD-G) on a current collector (Ni-foil) using reduced graphene oxide as an active electrode material to fabricate an electric double layer capacitor with reduced ESR. The CVD-G was grown at different cooling rates—20 °C min‑1, 40 °C min‑1 and 100 °C min‑1—to determine the optimum conditions. The lowest ESR, 0.38 Ω, was obtained for a cell with a 100 °C min‑1 cooling rate, while the sample without a CVD-G interlayer exhibited 0.80 Ω. The CVD-G interlayer-based supercapacitors exhibited fast CD characteristics with high scan rates up to 10 Vs‑1 due to low ESR. The specific capacitances deposited with CVD-G were in the range of 145.6 F g‑1–213.8 F g‑1 at a voltage scan rate of 0.05 V s‑1. A quasi-rectangular behavior was observed in the cyclic voltammetry curves, even at very high scan rates of 50 and 100 V s‑1, for the cell with optimized CVD-G at higher cooling rates, i.e. 100 °C min‑1.

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.

Turbostratic stacked CVD graphene for high-performance devices

Science.gov (United States)

Uemura, Kohei; Ikuta, Takashi; Maehashi, Kenzo

2018-03-01

We have fabricated turbostratic stacked graphene with high-transport properties by the repeated transfer of CVD monolayer graphene. The turbostratic stacked CVD graphene exhibited higher carrier mobility and conductivity than CVD monolayer graphene. The electron mobility for the three-layer turbostratic stacked CVD graphene surpassed 10,000 cm2 V-1 s-1 at room temperature, which is five times greater than that for CVD monolayer graphene. The results indicate that the high performance is derived from maintenance of the linear band dispersion, suppression of the carrier scattering, and parallel conduction. Therefore, turbostratic stacked CVD graphene is a superior material for high-performance devices.

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.

Catalytic growth of vertically aligned neutron sensitive 10Boron nitride nanotubes

International Nuclear Information System (INIS)

Ahmad, Pervaiz; Khandaker, Mayeen Uddin; Amin, Yusoff Mohd; Khan, Ghulamullah; Ramay, Shahid M.; Mahmood, Asif; Amin, Muhammad; Muhammad, Nawshad

2016-01-01

10 Boron nitride nanotubes ( 10 BNNTs) are a potential neutron sensing element in a solid-state neutron detector. The aligned 10 BNNT can be used for its potential application without any further purification. Argon-supported thermal CVD is used to achieve vertically aligned 10 BNNT with the help of nucleation sites produced in a thin layer of magnesium–iron alloy deposited at the top of Si substrate. FESEM shows vertically aligned 10 BNNTs with ball-like catalytic tips at top. EDX reveals magnesium (Mg) contents in the tips that refer to catalytic growth of 10 BNNT. HR-TEM shows tubular morphology of the synthesized 10 BNNT with lattice fringes on its outer part having an interlayer spacing of ∼0.34 nm. XPS shows B 1 s and N 1 s peaks at 190.5 and 398 eV that correspond to hexagonal 10 Boron nitride ( 10 h-BN) nature of the synthesized 10 BNNT, whereas the Mg kll auger peaks at ∼301 and ∼311 eV represents Mg contents in the sample. Raman spectrum has a peak at 1390 (cm −1 ) that corresponds to E 2g mode of vibration in 10 h-BN

CVD diamond windows for infrared synchrotron applications

International Nuclear Information System (INIS)

Sussmann, R.S.; Pickles, C.S.J.; Brandon, J.R.; Wort, C.J.H.; Coe, S.E.; Wasenczuk, A.; Dodge, C.N.; Beale, A.C.; Krehan, A.J.; Dore, P.; Nucara, A.; Calvani, P.

1998-01-01

This paper describes the attributes that make diamond a unique material for infrared synchrotron beam experiments. New developments in diamond synthesised by Chemical Vapour Deposition (CVD) promise to extend the range of applications which have been hitherto limited by the availability and cost of large-size single-crystal diamond. Polycrystalline CVD diamond components such as large (100 mm) diameter windows with extremely good transparency over a wide spectral range are now commercially available. Properties of CVD diamond of relevance to optical applications, such as mechanical strength, thermal conductivity and absolute bulk absorption, are discussed. It is shown that although some of the properties of CVD diamond (similar to other polycrystalline industrial ceramics) are affected by the grain structure, currently produced CVD diamond optical components have the quality and performance required for numerous demanding applications

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.)

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

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

CVD diamond for nuclear detection applications

International Nuclear Information System (INIS)

Bergonzo, P.; Brambilla, A.; Tromson, D.; Mer, C.; Guizard, B.; Marshall, R.D.; Foulon, F.

2002-01-01

Chemically vapour deposited (CVD) diamond is a remarkable material for the fabrication of radiation detectors. In fact, there exist several applications where other standard semiconductor detectors do not fulfil the specific requirements imposed by corrosive, hot and/or high radiation dose environments. The improvement of the electronic properties of CVD diamond has been under intensive investigations and led to the development of a few applications that are addressing specific industrial needs. Here, we report on CVD diamond-based detector developments and we describe how this material, even though of a polycrystalline nature, is readily of great interest for applications in the nuclear industry as well as for physics experiments. Improvements in the material synthesis as well as on device fabrication especially concern the synthesis of films that do not exhibit space charge build up effects which are often encountered in CVD diamond materials and that are highly detrimental for detection devices. On a pre-industrial basis, CVD diamond detectors have been fabricated for nuclear industry applications in hostile environments. Such devices can operate in harsh environments and overcome limitations encountered with the standard semiconductor materials. Of these, this paper presents devices for the monitoring of the alpha activity in corrosive nuclear waste solutions, such as those encountered in nuclear fuel assembly reprocessing facilities, as well as diamond-based thermal neutron detectors exhibiting a high neutron to gamma selectivity. All these demonstrate the effectiveness of a demanding industrial need that relies on the remarkable resilience of CVD diamond

Carbon diffusion in uncoated and titanium nitride coated iron substrates during microwave plasma assisted chemical vapor deposition of diamond

International Nuclear Information System (INIS)

Weiser, P.S.; Prawer, S.; Manory, R.R.; Paterson, P.J.K.; Stuart, Sue-Anne

1992-01-01

Auger Electron Spectroscopy has been employed to investigate the effectiveness of thin films of TiN as barriers to carbon diffusion during Chemical Vapor Deposition (CVD) of diamond onto Fe substrates. Auger Depth Profiling was used to monitor the C concentration in the TiN layer, through the interface and into the substrate both before and after CVD diamond deposition. The results show that a layer of TiN only 250 Angstroems thick is sufficient to inhibit soot formation on the Fe surface and C diffusion into the Fe bulk. 14 refs., 4 figs

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.

Possibility of the use of intermediate carbidsiliconoxide nanolayers on polydiamond substrates for gallium nitride layers epitaxy

Energy Technology Data Exchange (ETDEWEB)

Averichkin, P. A., E-mail: P-Yugov@mail.ru; Donskov, A. A. [State Research and Design Institute of Rare-Metal Industry Giredmet AO (Russian Federation); Dukhnovsky, M. P. [R & D Enterprise Istok (Russian Federation); Knyazev, S. N. [State Research and Design Institute of Rare-Metal Industry Giredmet AO (Russian Federation); Kozlova, Yu. P. [Russian Academy of Sciences, Institute for Nuclear Research (Russian Federation); Yugova, T. G.; Belogorokhov, I. A. [State Research and Design Institute of Rare-Metal Industry Giredmet AO (Russian Federation)

2016-04-15

The results of using carbidsiliconoxide (a-C:SiO1{sub .5}) films with a thickness of 30–60 nm, produced by the pyrolysis annealing of oligomethylsilseskvioksana (CH{sub 3}–SiO{sub 1.5}){sub n} with cyclolinear (staircased) molecular structure, as intermediate films in the hydride vapor phase epitaxy of gallium nitride on polycrystalline CVD-diamond substrates are presented. In the pyrolysis annealing of (CH{sub 3}–SiO{sub 1.5}){sub n} films in an atmosphere of nitrogen at a temperature of 1060°C, methyl radicals are carbonized to yield carbon atoms chemically bound to silicon. In turn, these atoms form a SiC monolayer on the surface of a-C:SiO{sub 1.5} films via covalent bonding with silicon. It is shown that GaN islands grow on such an intermediate layer on CVD-polydiamond substrates in the process of hydride vapor phase epitaxy in a vertical reactor from the GaCl–NH{sub 3}–N{sub 2} gas mixture.

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.

Fermented dairy food and CVD risk.

Science.gov (United States)

Tapsell, Linda C

2015-04-01

Fermented dairy foods such as yoghurt and cheese are commonly found in the Mediterranean diet. Recent landmark research has confirmed the effect of the Mediterranean diet on reducing the CVD risk, but the relative contributions of fermented dairy foods have not been fully articulated. The present study provides a review of the relationship between fermented dairy foods consumption and CVD risk in the context of the whole diet. Studies show that people who eat healthier diets may be more likely to consume yoghurt, so there is a challenge in attributing separate effects to yoghurt. Analyses from large population studies list yoghurt as the food most negatively associated with the risk of weight gain (a problem that may lead to CVD). There is some suggestion that fermented dairy foods consumption (yoghurt or cheese) may be associated with reduced inflammatory biomarkers associated with the development of CVD. Dietary trials suggest that cheese may not have the same effect on raising LDL-cholesterol levels as butter with the same saturated fat content. The same might be stated for yoghurt. The use of different probiotic cultures and other aspects of study design remain a problem for research. Nevertheless, population studies from a range of countries have shown that a reduced risk of CVD occurs with the consumption of fermented dairy foods. A combination of evidence is necessary, and more research is always valuable, but indications remain that fermented dairy foods such as cheese and yoghurt are integral to diets that are protective against CVD.

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.)

Chemical-vapor-infiltrated silicon nitride, boron nitride, and silicon carbide matrix composites

International Nuclear Information System (INIS)

Ventri, R.D.; Galasso, F.S.

1990-01-01

This paper reports composites of carbon/chemical-vapor-deposited (CVD) Si 3 N 4 , carbon/CVD BN, mullite/CVD SiC, and SiC yarn/CVD SiC prepared to determine if there were inherent toughness in these systems. The matrices were deposited at high enough temperatures to ensure that they were crystalline, which should make them more stable at high temperatures. The fiber-matrix bonding in the C/Si 3 N 4 composite appeared to be too strong; the layers of BN in the matrix of the C/BN were too weakly bonded; and the mullite/SiC composite was not as tough as the SiC/SiC composites. Only the SiC yarn/CVD SiC composite exhibited both strength and toughness

CVD diamond for nuclear detection applications

CERN Document Server

Bergonzo, P; Tromson, D; Mer, C; Guizard, B; Marshall, R D; Foulon, F

2002-01-01

Chemically vapour deposited (CVD) diamond is a remarkable material for the fabrication of radiation detectors. In fact, there exist several applications where other standard semiconductor detectors do not fulfil the specific requirements imposed by corrosive, hot and/or high radiation dose environments. The improvement of the electronic properties of CVD diamond has been under intensive investigations and led to the development of a few applications that are addressing specific industrial needs. Here, we report on CVD diamond-based detector developments and we describe how this material, even though of a polycrystalline nature, is readily of great interest for applications in the nuclear industry as well as for physics experiments. Improvements in the material synthesis as well as on device fabrication especially concern the synthesis of films that do not exhibit space charge build up effects which are often encountered in CVD diamond materials and that are highly detrimental for detection devices. On a pre-i...

TiCx thin films coatings prepared by reactive sputtering

International Nuclear Information System (INIS)

Saoula, N.; Handa, K.; Kesri, R.

2004-01-01

Full text.Transition metal carbides and nitrides attract large technological interest due to their unique properties like high hardness and young modulus, high electric conductivity, a considerable high-temperature strength, high corrosion resistance and high melting or decomposition temperatures. They have been applied as coatings for tools because of their superior properties. these materials have such properties due to atomic bonding, which shows a mixed covalent, metallic and ionic character. Among these nitrides and carbides titanium carbide is a compound of particular importance. Titanium carbide combines the advantages of a high melting point (3140 celsius degree) and hardness (3000 Hv) with those of relative lightness (density 4.93 10 3 Kg m -3 ).It also exhibits high resistance to both corrosion and oxidation and a relatively low friction coefficient. Usually, TiC films are produced by deposition with plasma-enhanced CVD (PCVD), thermal chemical vapour deposition (CVD) or activated reactive evaporation methods. However, these methods require high temperature (>600 celsius degree) substrates to achieve the deposition, which sometimes causes thermal damage to the deposited films. At temperature above 550 celsius degree, thermal diffusion of materials not suitable may also occur. In addition, it has been reported that the maximum temperature which permits the appropriate coating of hardened steel tools is 500 celsius degree. Therefore, it is desirable to develop a deposition technique for TiC films using low-temperature substrates to avoid thermal damage. So, different physical vapour deposition (PVD) processes for deposition of TiC at relatively low temperatures have been used through the years. These processes are based on vaporisation of titanium in hydrocarbon atmosphere or on sputtering of solid TiC target or titanium target in hydrocarbon atmosphere. the most often-used hydrocarbon gases are methane, acetylene, ethene and ethane. In previous works, we

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

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.

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.

MgO by injection CVD

International Nuclear Information System (INIS)

Abrutis, A.; Kubilius, V.; Teiserkis, A.; Bigelyte, V.; Vengalis, B.; Jukna, A.; Butkute, R.

1997-01-01

Epitaxial YBa 2 Cu 3 O 7 layers with 45 in-plane orientation have been grown by injection CVD on MgO substrates polished off-axis to within 1.4-1.9 of the [100] direction. This new single-source CVD process is based on computer-controlled injection of precise microdoses of a metal-organic precursor solution into a CVD reactor. A wide range of solution compositions was tested to investigate compositional effects on phase purity, surface morphology, texturing and superconducting properties of the prepared films. The highest quality films with pure 45 texture had a smooth surface, zero resistance T c (R=0) of 88-89 K, and critical current density J c (77 K) above 10 6 A/cm 2 . (orig.) and critical current density J c (77 K) above 10 6 A/cm 2 . (orig.)

Direct growth of nanocrystalline hexagonal boron nitride films on dielectric substrates

Energy Technology Data Exchange (ETDEWEB)

Tay, Roland Yingjie [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); Temasek Laboratories@NTU, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); Tsang, Siu Hon [Temasek Laboratories@NTU, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); Loeblein, Manuela; Chow, Wai Leong [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); CNRS-International NTU Thales Research Alliance CINTRA UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Singapore, Singapore 637553 (Singapore); Loh, Guan Chee [Institue of High Performance Computing, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632 (Singapore); Department of Physics, Michigan Technological University, Houghton, Michigan 49931 (United States); Toh, Joo Wah; Ang, Soon Loong [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); Teo, Edwin Hang Tong, E-mail: htteo@ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore)

2015-03-09

Atomically thin hexagonal-boron nitride (h-BN) films are primarily synthesized through chemical vapor deposition (CVD) on various catalytic transition metal substrates. In this work, a single-step metal-catalyst-free approach to obtain few- to multi-layer nanocrystalline h-BN (NCBN) directly on amorphous SiO{sub 2}/Si and quartz substrates is demonstrated. The as-grown thin films are continuous and smooth with no observable pinholes or wrinkles across the entire deposited substrate as inspected using optical and atomic force microscopy. The starting layers of NCBN orient itself parallel to the substrate, initiating the growth of the textured thin film. Formation of NCBN is due to the random and uncontrolled nucleation of h-BN on the dielectric substrate surface with no epitaxial relation, unlike on metal surfaces. The crystallite size is ∼25 nm as determined by Raman spectroscopy. Transmission electron microscopy shows that the NCBN formed sheets of multi-stacked layers with controllable thickness from ∼2 to 25 nm. The absence of transfer process in this technique avoids any additional degradation, such as wrinkles, tears or folding and residues on the film which are detrimental to device performance. This work provides a wider perspective of CVD-grown h-BN and presents a viable route towards large-scale manufacturing of h-BN substrates and for coating applications.

Application of CVD diamond film for radiation detection

International Nuclear Information System (INIS)

Zhou Haiyang; Zhu Xiaodong; Zhan Rujuan

2005-01-01

With the development of diamond synthesis at low pressure, the CVD diamond properties including electronic characteristics have improved continuously. Now the fabrication of electronic devices based on the CVD diamond has been one of hot research subjects in this field. Due to many unique advantages, such as high signal-noise ratio, fast time response, and normal output in extremely harsh surrounding, the CVD diamond radiation detector has attracted more and more interest. In this paper, we have reviewed the development and status of the CVD diamond radiation detector. The prospect of this detector is described. (authors)

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.

P-type sp3-bonded BN/n-type Si heterodiode solar cell fabricated by laser-plasma synchronous CVD method

International Nuclear Information System (INIS)

Komatsu, Shojiro; Nagata, Takahiro; Chikyo, Toyohiro; Sato, Yuhei; Watanabe, Takayuki; Hirano, Daisuke; Takizawa, Takeo; Nakamura, Katsumitsu; Hashimoto, Takuya; Nakamura, Takuya; Koga, Kazunori; Shiratani, Masaharu; Yamamoto, Atsushi

2009-01-01

A heterojunction of p-type sp 3 -bonded boron nitride (BN) and n-type Si fabricated by laser-plasma synchronous chemical vapour deposition (CVD) showed excellent rectifying properties and proved to work as a solar cell with photovoltaic conversion efficiency of 1.76%. The BN film was deposited on an n-type Si (1 0 0) substrate by plasma CVD from B 2 H 6 + NH 3 + Ar while doping of Si into the BN film was induced by the simultaneous irradiation of an intense excimer laser with a pulse power of 490 mJ cm -2 , at a wavelength of 193 nm and at a repetition rate of 20 Hz. The source of dopant Si was supposed to be the Si substrate ablated at the initial stage of the film growth. The laser enhanced the doping (and/or diffusion) of Si into BN as well as the growth of sp 3 -bonded BN simultaneously in this method. P-type conduction of BN films was determined by the hot (thermoelectric) probe method. The BN/Si heterodiode with an essentially transparent p-type BN as a front layer is supposed to efficiently absorb light reaching the active region so as to potentially result in high efficiency.

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.)

Surface modification of titanium membrane by chemical vapor deposition and its electrochemical self-cleaning

Energy Technology Data Exchange (ETDEWEB)

Li, X.W., E-mail: lynnww@sohu.com [School of Electronic and Information Engieering, Tianjin university, Tianjin, 300072 (China); School of Electronics Information Engieering, Tianjin University of Technology, Tianjin, 300384 (China); Li, J.X. [Tianjin Polytechnic University, Tianjin 300160 (China); Gao, C.Y. [Chinese Peoples Armed Police Forces Academy, Langfang 065000 (China); Chang, M. [School of Electronic and Information Engieering, Tianjin university, Tianjin, 300072 (China); School of Electronics Information Engieering, Tianjin University of Technology, Tianjin, 300384 (China)

2011-10-15

Membrane separation is applied widely in many fields, while concentration polarization and membrane fouling, limiting its promotion and application greatly, are the bottlenecks in membrane application. Among which, membrane fouling is irreversible, membrane must be periodically cleaned or even replaced to restore permeability. Membrane cleaning has become one of Key issues in membrane separation areas. Considering incomparable electrochemical advantages of boron-doped diamond (BDD) film electrode over conventional electrode, a new composite membrane Ti/BDD, made by depositing CVD (chemical vapor deposition) boron-doped diamond film on titanium(Ti) membrane to modify porous titanium surface, that can be cleaned electrochemically is proposed. Feasibility of its preparation and application is discussed in this paper. Results shows that based on the unique electrochemical properties of diamond, cleaning level of this composite Ti/BDD membrane is significantly increased, making membrane life and efficiency improved prominently.

Surface modification of titanium membrane by chemical vapor deposition and its electrochemical self-cleaning

International Nuclear Information System (INIS)

Li, X.W.; Li, J.X.; Gao, C.Y.; Chang, M.

2011-01-01

Membrane separation is applied widely in many fields, while concentration polarization and membrane fouling, limiting its promotion and application greatly, are the bottlenecks in membrane application. Among which, membrane fouling is irreversible, membrane must be periodically cleaned or even replaced to restore permeability. Membrane cleaning has become one of Key issues in membrane separation areas. Considering incomparable electrochemical advantages of boron-doped diamond (BDD) film electrode over conventional electrode, a new composite membrane Ti/BDD, made by depositing CVD (chemical vapor deposition) boron-doped diamond film on titanium(Ti) membrane to modify porous titanium surface, that can be cleaned electrochemically is proposed. Feasibility of its preparation and application is discussed in this paper. Results shows that based on the unique electrochemical properties of diamond, cleaning level of this composite Ti/BDD membrane is significantly increased, making membrane life and efficiency improved prominently.

Hydride vapor phase epitaxy growth of GaN, InGaN, ScN, and ScAIN

NARCIS (Netherlands)

Bohnen, T.

2010-01-01

Chemical vapor deposition (CVD); hydride vapor phase epitaxy (HVPE); gallium nitride (GaN); indium gallium nitride (InGaN); scandium nitride (ScN); scandium aluminum nitride (ScAlN); semiconductors; thin films; nanowires; III nitrides; crystal growth - We studied the HVPE growth of different III

New developments in CVD diamond for detector applications

Science.gov (United States)

Adam, W.; Berdermann, E.; Bergonzo, P.; de Boer, W.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; D'Angelo, P.; Dabrowski, W.; Delpierre, P.; Dulinski, W.; Doroshenko, J.; van Eijk, B.; Fallou, A.; Fischer, P.; Fizzotti, F.; Furetta, C.; Gan, K. K.; Ghodbane, N.; Grigoriev, E.; Hallewell, G.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kaplon, J.; Kass, R.; Keil, M.; Knoepfle, K. T.; Koeth, T.; Krammer, M.; Logiudice, A.; Lu, R.; Mac Lynne, L.; Manfredotti, C.; Meier, D.; Menichelli, D.; Meuser, S.; Mishina, M.; Moroni, L.; Noomen, J.; Oh, A.; Pernicka, M.; Perera, L.; Potenza, R.; Riester, J. L.; Roe, S.; Rudge, A.; Sala, S.; Sampietro, M.; Schnetzer, S.; Sciortino, S.; Stelzer, H.; Stone, R.; Sutera, C.; Trischuk, W.; Tromson, D.; Tuve, C.; Vincenzo, B.; Weilhammer, P.; Wermes, N.; Wetstein, M.; Zeuner, W.; Zoeller, M.

Chemical Vapor Deposition (CVD) diamond has been discussed extensively as an alternative sensor material for use very close to the interaction region of the LHC and other machines where extreme radiation conditions exist. During the last seven years the RD42 collaboration has developed diamond detectors and tested them with LHC electronics towards the end of creating a device usable by experiments. The most recent results of this work are presented. Recently, a new form of CVD diamond has been developed: single crystal CVD diamond which resolves many of the issues associated with poly-crystalline CVD material. The first tests of this material are also presented.

New developments in CVD diamond for detector applications

Energy Technology Data Exchange (ETDEWEB)

Adam, W. [HEPHY, Vienna (Austria); Berdermann, E. [GSI, Darmstadt (Germany); Bergonzo, P.; Brambilla, A. [LETI/DEIN/SPE/CEA Saclay (France); Boer, W. de [Universitaet Karlsruhe, Karlsruhe (Germany); Bogani, F. [LENS, Florence (Italy); Borchi, E.; Bruzzi, M. [University of Florence (Italy); Colledani, C.; Dulinski, W. [LEPSI, IN2P3/CNRS-ULP, Strasbourg (France); Conway, J.; Doroshenko, J. [Rutgers University, Piscataway (United States); D' Angelo, P.; Furetta, C. [INFN, Milano (Italy); Dabrowski, W. [UMM, Cracow (Poland); Delpierre, P.; Fallou, A. [CPPM, Marseille (France); Eijk, B. van [NIKHEF, Amsterdam (Netherlands); Fischer, P. [Universitaet Bonn, Bonn (Germany); Fizzotti, F. [University of Torino (Italy); Gan, K.K.; Ghodbane, N.; Grigoriev, E.; Hallewell, G.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kaplon, J.; Kass, R.; Keil, M.; Knoepfle, K.T.; Koeth, T.; Krammer, M.; Logiudice, A.; Lu, R.; Mac Lynne, L.; Manfredotti, C.; Meier, D.; Menichelli, D.; Meuser, S.; Mishina, M.; Moroni, L.; Noomen, J.; Oh, A.; Pernicka, M.; Perera, L.; Potenza, R.; Riester, J.L.; Roe, S.; Rudge, A.; Sala, S.; Sampietro, M.; Schnetzer, S.; Sciortino, S.; Stelzer, H.; Stone, R.; Sutera, C.; Trischuk, W.; Tromson, D.; Tuve, C.; Vincenzo, B.; Weilhammer, P.; Wermes, N.; Wetstein, M.; Zeuner, W.; Zoeller, M.

2004-07-01

Chemical Vapor Deposition (CVD) diamond has been discussed extensively as an alternative sensor material for use very close to the interaction region of the LHC and other machines where extreme radiation conditions exist. During the last seven years the RD42 collaboration has developed diamond detectors and tested them with LHC electronics towards the end of creating a device usable by experiments. The most recent results of this work are presented. Recently, a new form of CVD diamond has been developed: single crystal CVD diamond which resolves many of the issues associated with poly-crystalline CVD material. The first tests of this material are also presented. (orig.)

New developments in CVD diamond for detector applications

International Nuclear Information System (INIS)

Adam, W.; Berdermann, E.; Bergonzo, P.; Brambilla, A.; Boer, W. de; Bogani, F.; Borchi, E.; Bruzzi, M.; Colledani, C.; Dulinski, W.; Conway, J.; Doroshenko, J.; D'Angelo, P.; Furetta, C.; Dabrowski, W.; Delpierre, P.; Fallou, A.; Eijk, B. van; Fischer, P.; Fizzotti, F.; Gan, K.K.; Ghodbane, N.; Grigoriev, E.; Hallewell, G.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kaplon, J.; Kass, R.; Keil, M.; Knoepfle, K.T.; Koeth, T.; Krammer, M.; Logiudice, A.; Lu, R.; Mac Lynne, L.; Manfredotti, C.; Meier, D.; Menichelli, D.; Meuser, S.; Mishina, M.; Moroni, L.; Noomen, J.; Oh, A.; Pernicka, M.; Perera, L.; Potenza, R.; Riester, J.L.; Roe, S.; Rudge, A.; Sala, S.; Sampietro, M.; Schnetzer, S.; Sciortino, S.; Stelzer, H.; Stone, R.; Sutera, C.; Trischuk, W.; Tromson, D.; Tuve, C.; Vincenzo, B.; Weilhammer, P.; Wermes, N.; Wetstein, M.; Zeuner, W.; Zoeller, M.

2004-01-01

Chemical Vapor Deposition (CVD) diamond has been discussed extensively as an alternative sensor material for use very close to the interaction region of the LHC and other machines where extreme radiation conditions exist. During the last seven years the RD42 collaboration has developed diamond detectors and tested them with LHC electronics towards the end of creating a device usable by experiments. The most recent results of this work are presented. Recently, a new form of CVD diamond has been developed: single crystal CVD diamond which resolves many of the issues associated with poly-crystalline CVD material. The first tests of this material are also presented. (orig.)

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

Micro-strip sensors based on CVD diamond

Energy Technology Data Exchange (ETDEWEB)

Adam, W.; Berdermann, E.; Bergonzo, P.; Bertuccio, G.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; D' Angelo, P.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; Eijk, B. van; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K.K.; Gheeraert, E.; Hallewell, G.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Kass, R.; Koeth, T.; Krammer, M.; Logiudice, A.; Lu, R.; Mac Lynne, L.; Manfredotti, C.; Meier, D. E-mail: dirk.meier@cern.ch; Mishina, M.; Moroni, L.; Oh, A.; Pan, L.S.; Pernicka, M.; Peitz, A.; Perera, L.; Pirollo, S.; Procario, M.; Riester, J.L.; Roe, S.; Rousseau, L.; Rudge, A.; Russ, J.; Sala, S.; Sampietro, M.; Schnetzer, S.; Sciortino, S.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R.J.; Tesarek, R.; Trischuk, W.; Tromson, D.; Vittone, E.; Walsh, A.M.; Wedenig, R.; Weilhammer, P.; Wetstein, M.; White, C.; Zeuner, W.; Zoeller, M

2000-10-11

In this article we present the performance of recent chemical vapour deposition (CVD) diamond micro-strip sensors in beam tests. In addition, we present the first comparison of a CVD diamond micro-strip sensor before and after proton irradiation.

Micro-strip sensors based on CVD Diamond

CERN Document Server

Adam, W; Bergonzo, P; Bertuccio, G; Bogani, F; Borchi, E; Brambilla, A; Bruzzi, Mara; Colledani, C; Conway, J; D'Angelo, P; Dabrowski, W; Delpierre, P A; Deneuville, A; Dulinski, W; van Eijk, B; Fallou, A; Fizzotti, F; Foulon, F; Friedl, M; Gan, K K; Gheeraert, E; Hallewell, G D; Han, S; Hartjes, F G; Hrubec, Josef; Husson, D; Kagan, H; Kania, D R; Kaplon, J; Kass, R; Koeth, T W; Krammer, Manfred; Lo Giudice, A; Lü, R; MacLynne, L; Manfredotti, C; Meier, D; Mishina, M; Moroni, L; Oh, A; Pan, L S; Pernicka, Manfred; Peitz, A; Perera, L P; Pirollo, S; Procario, M; Riester, J L; Roe, S; Rousseau, L; Rudge, A; Russ, J; Sala, S; Sampietro, M; Schnetzer, S R; Sciortino, S; Stelzer, H; Stone, R; Suter, B; Tapper, R J; Tesarek, R J; Trischuk, W; Tromson, D; Vittone, E; Walsh, A M; Wedenig, R; Weilhammer, Peter; Wetstein, M; White, C; Zeuner, W; Zoeller, M M

2000-01-01

In this article we present the performance of recent chemical vapour deposition (CVD) diamond micro-strip sensors in beam tests. In addition we present the first comparison of a CVD diamond micro-strip sensor before and after proton irradiation.

Micro-strip sensors based on CVD diamond

International Nuclear Information System (INIS)

Adam, W.; Berdermann, E.; Bergonzo, P.; Bertuccio, G.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; D'Angelo, P.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; Eijk, B. van; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K.K.; Gheeraert, E.; Hallewell, G.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Kass, R.; Koeth, T.; Krammer, M.; Logiudice, A.; Lu, R.; Mac Lynne, L.; Manfredotti, C.; Meier, D.; Mishina, M.; Moroni, L.; Oh, A.; Pan, L.S.; Pernicka, M.; Peitz, A.; Perera, L.; Pirollo, S.; Procario, M.; Riester, J.L.; Roe, S.; Rousseau, L.; Rudge, A.; Russ, J.; Sala, S.; Sampietro, M.; Schnetzer, S.; Sciortino, S.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R.J.; Tesarek, R.; Trischuk, W.; Tromson, D.; Vittone, E.; Walsh, A.M.; Wedenig, R.; Weilhammer, P.; Wetstein, M.; White, C.; Zeuner, W.; Zoeller, M.

2000-01-01

In this article we present the performance of recent chemical vapour deposition (CVD) diamond micro-strip sensors in beam tests. In addition, we present the first comparison of a CVD diamond micro-strip sensor before and after proton irradiation

Micro-strip sensors based on CVD diamond

Science.gov (United States)

Adam, W.; Berdermann, E.; Bergonzo, P.; Bertuccio, G.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; D'Angelo, P.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; van Eijk, B.; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K. K.; Gheeraert, E.; Hallewell, G.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Kass, R.; Koeth, T.; Krammer, M.; Logiudice, A.; Lu, R.; mac Lynne, L.; Manfredotti, C.; Meier, D.; Mishina, M.; Moroni, L.; Oh, A.; Pan, L. S.; Pernicka, M.; Peitz, A.; Perera, L.; Pirollo, S.; Procario, M.; Riester, J. L.; Roe, S.; Rousseau, L.; Rudge, A.; Russ, J.; Sala, S.; Sampietro, M.; Schnetzer, S.; Sciortino, S.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R. J.; Tesarek, R.; Trischuk, W.; Tromson, D.; Vittone, E.; Walsh, A. M.; Wedenig, R.; Weilhammer, P.; Wetstein, M.; White, C.; Zeuner, W.; Zoeller, M.; RD42 Collaboration

2000-10-01

In this article we present the performance of recent chemical vapour deposition (CVD) diamond micro-strip sensors in beam tests. In addition, we present the first comparison of a CVD diamond micro-strip sensor before and after proton irradiation.

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)

A measure of the interfacial shear strength between SiC(CVD)/B(CVD) filament--aluminum matrix by fragmentation method

International Nuclear Information System (INIS)

Jiang, Y.Q.; Chen, X.J.; Yang, D.M.; Fei, X.; Pan, J.

1993-01-01

The tensile specimens used are of dog-bone shape and consist of single axial SiC (CVD) /B (CVD) filament processed by CVD and embedded in a LD-2 aluminum alloy. Model composite specimens have been fabricated by a high pressure squeeze casting technique. This paper describes the application of an Acoustic Emission Technique for locating the position of fiber breaks and thus determining the length distribution of fiber fragments resulting when a composite specimen containing a single fiber is loaded to failure. The critical lengths (minimal lengths) are checked by Corrosion Method

Catalytic growth of vertically aligned neutron sensitive {sup 10}Boron nitride nanotubes

Energy Technology Data Exchange (ETDEWEB)

Ahmad, Pervaiz, E-mail: pervaizahmad@siswa.um.edu.my, E-mail: Pervaiz-pas@yahoo.com; Khandaker, Mayeen Uddin, E-mail: mu-khandaker@yahoo.com, E-mail: mu-khandaker@um.edu.my; Amin, Yusoff Mohd [University of Malaya, Department of Physics, Faculty of Science (Malaysia); Khan, Ghulamullah [University of Malaya, Department of Mechanical Engineering (Malaysia); Ramay, Shahid M. [King Saud University, Department of Physics and Astronomy, College of Science (Saudi Arabia); Mahmood, Asif [King Saud University, Department of Chemical Engineering, College of Engineering (Saudi Arabia); Amin, Muhammad [University of the Punjab, Department of Physics (Pakistan); Muhammad, Nawshad [Interdisciplinary Research Centre in Biomedical Materials (IRCBM) COMSATS Institute of Information Technology (Pakistan)

2016-01-15

{sup 10}Boron nitride nanotubes ({sup 10}BNNTs) are a potential neutron sensing element in a solid-state neutron detector. The aligned {sup 10}BNNT can be used for its potential application without any further purification. Argon-supported thermal CVD is used to achieve vertically aligned {sup 10}BNNT with the help of nucleation sites produced in a thin layer of magnesium–iron alloy deposited at the top of Si substrate. FESEM shows vertically aligned {sup 10}BNNTs with ball-like catalytic tips at top. EDX reveals magnesium (Mg) contents in the tips that refer to catalytic growth of {sup 10}BNNT. HR-TEM shows tubular morphology of the synthesized {sup 10}BNNT with lattice fringes on its outer part having an interlayer spacing of ∼0.34 nm. XPS shows B 1 s and N 1 s peaks at 190.5 and 398 eV that correspond to hexagonal {sup 10}Boron nitride ({sup 10}h-BN) nature of the synthesized {sup 10}BNNT, whereas the Mg kll auger peaks at ∼301 and ∼311 eV represents Mg contents in the sample. Raman spectrum has a peak at 1390 (cm{sup −1}) that corresponds to E{sub 2g} mode of vibration in {sup 10}h-BN.

An assessment of radiotherapy dosimeters based on CVD grown diamond

International Nuclear Information System (INIS)

Ramkumar, S.; Buttar, C.M.; Conway, J.; Whitehead, A.J.; Sussman, R.S.; Hill, G.; Walker, S.

2001-01-01

Diamond is potentially a very suitable material for use as a dosimeter for radiotherapy. Its radiation hardness, the near tissue equivalence and chemical inertness are some of the characteristics of diamond, which make it well suited for its application as a dosimeter. Recent advances in the synthesis of diamond by chemical vapour deposition (CVD) technology have resulted in the improvement in the quality of material and increased its suitability for radiotherapy applications. We report in this paper, the response of prototype dosimeters based on two different types (CVD1 and CVD2) of CVD diamond to X-rays. The diamond devices were assessed for sensitivity, dependence of response on dose and dose rate, and compared with a Scanditronix silicon photon diode and a PTW natural diamond dosimeter. The diamond devices of CVD1 type showed an initial increase in response with dose, which saturates after ∼6 Gy. The diamond devices of CVD2 type had a response at low fields ( 1162.8 V/cm), the CVD2-type devices showed polarisation and dose-rate dependence. The sensitivity of the CVD diamond devices varied between 82 and 1300 nC/Gy depending upon the sample type and the applied voltage. The sensitivity of CVD diamond devices was significantly higher than that of natural diamond and silicon dosimeters. The results suggest that CVD diamond devices can be fabricated for successful use in radiotherapy applications

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.

Glass fabrics self-cracking catalytic growth of boron nitride nanotubes

Science.gov (United States)

Wang, Jilin; Peng, Daijang; Long, Fei; Wang, Weimin; Gu, Yunle; Mo, Shuyi; Zou, Zhengguang; Fu, Zhengyi

2017-02-01

Glass fabrics were used to fabricate boron nitride nanotubes (BNNTs) with a broad diameter range through a combined chemical vapor deposition and self-propagation high-temperature synthesis (CVD-SHS) method at different holding times (0min, 30min, 90min, 180min and 360min). SEM characterization has been employed to investigate the macro and micro structure/morphology changes of the glass fabrics and BNNTs in detail. SEM image analysis has provided direct experimental evidences for the rationality of the optimized self-cracking catalyst VLS growth mechanism, including the transformation situations of the glass fabrics and the BNNTs growth processes respectively. This paper was the further research and compensation for the theory and experiment deficiencies in the new preparation method of BNNTs reported in our previous work. In addition, it is likely that the distinctive self-cracking catalyst VLS growth mechanism could provide a new idea to preparation of other inorganic functional nano-materials using similar one-dimensional raw materials as growth templates and catalysts.

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

CVD Diamond Sensors In Detectors For High Energy Physics

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00334150; Trischuk, William

At the end of the next decade an upgrade of the Large Hadron Collider (LHC) to High Luminosity LHC (HL-LHC) is planned which requires the development of new radiation tolerant sensor technology. Diamond is an interesting material for use as a particle detector in high radiation environments. The large band gap ($5.47\\,\\text{eV}$) and the large displacement energy suggest that diamond is a radiation tolerant detector material. In this Thesis the capability of Chemical Vapor Deposition (CVD) diamond as such a sensor technology is investigated. The radiation damage constant for $800\\,\\text{MeV}$ protons is measured using single crystalline CVD (scCVD) and polycrystalline CVD (pCVD) diamonds irradiated to particle fluences up to $12 \\times 10^{15}\\,\\text{p/cm}^2$. In addition the signal response of a pCVD diamond detector after an irradiation to $12 \\times 10^{15}\\,\\text{p/cm}^2$ is investigated to determine if such a detector can be operated efficiently in the expected HL-LHC environment. By using electrodes em...

Wettability Investigations and Wet Transfer Enhancement of Large-Area CVD-Graphene on Aluminum Nitride.

Science.gov (United States)

Knapp, Marius; Hoffmann, René; Cimalla, Volker; Ambacher, Oliver

2017-08-18

The two-dimensional and virtually massless character of graphene attracts great interest for radio frequency devices, such as surface and bulk acoustic wave resonators. Due to its good electric conductivity, graphene might be an alternative as a virtually massless electrode by improving resonator performance regarding mass-loading effects . We report on an optimization of the commonly used wet transfer technique for large-area graphene, grown via chemical vapor deposition, onto aluminum nitride (AlN), which is mainly used as an active, piezoelectric material for acoustic devices. Today, graphene wet transfer is well-engineered for silicon dioxide (SiO₂). Investigations on AlN substrates reveal highly different surface properties compared to SiO₂ regarding wettability, which strongly influences the quality of transferred graphene monolayers. Both physical and chemical effects of a plasma treatment of AlN surfaces change wettability and avoid large-scale cracks in the transferred graphene sheet during desiccation. Spatially-resolved Raman spectroscopy reveals a strong strain and doping dependence on AlN plasma pretreatments correlating with the electrical conductivity of graphene. In our work, we achieved transferred crack-free large-area (40 × 40 mm²) graphene monolayers with sheet resistances down to 350 Ω/sq. These achievements make graphene more powerful as an eco-friendly and cheaper replacement for conventional electrode materials used in radio frequency resonator devices.

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.

The gate oxide integrity of CVD tungsten polycide

International Nuclear Information System (INIS)

Wu, N.W.; Su, W.D.; Chang, S.W.; Tseng, M.F.

1988-01-01

CVD tungsten polycide has been demonstrated as a good gate material in recent very large scale integration (VLSI) technology. CVD tungsten silicide offers advantages of low resistivity, high temperature stability and good step coverage. On the other hand, the polysilicon underlayer preserves most characteristics of the polysilicon gate and acts as a stress buffer layer to absorb part of the thermal stress origin from the large thermal expansion coefficient of tungsten silicide. Nevertheless, the gate oxide of CVD tungsten polycide is less stable or reliable than that of polysilicon gate. In this paper, the gate oxide integrity of CVD tungsten polycide with various thickness combinations and different thermal processes have been analyzed by several electrical measurements including breakdown yield, breakdown fluence, room temperature TDDB, I-V characteristics, electron traps and interface state density

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.

Ion beam figuring of CVD silicon carbide mirrors

Science.gov (United States)

Gailly, P.; Collette, J.-P.; Fleury Frenette, K.; Jamar, C.

2017-11-01

Optical and structural elements made of silicon carbide are increasingly found in space instruments. Chemical vapor deposited silicon carbide (CVD-SiC) is used as a reflective coating on SiC optics in reason of its good behavior under polishing. The advantage of applying ion beam figuring (IBF) to CVD-SiC over other surface figure-improving techniques is discussed herein. The results of an IBF sequence performed at the Centre Spatial de Liège on a 100 mm CVD-SiC mirror are reported. The process allowed to reduce the mirror surface errors from 243 nm to 13 nm rms . Beside the surface figure, roughness is another critical feature to consider in order to preserve the optical quality of CVD-SiC . Thus, experiments focusing on the evolution of roughness were performed in various ion beam etching conditions. The roughness of samples etched at different depths down to 3 ≠m was determined with an optical profilometer. These measurements emphasize the importance of selecting the right combination of gas and beam energy to keep roughness at a low level. Kaufman-type ion sources are generally used to perform IBF but the performance of an end-Hall ion source in figuring CVD-SiC mirrors was also evaluated in this study. In order to do so, ion beam etching profiles obtained with the end-Hall source on CVD-SiC were measured and used as a basis for IBF simulations.

Low-temperature graphene synthesis using microwave plasma CVD

International Nuclear Information System (INIS)

Yamada, Takatoshi; Kim, Jaeho; Ishihara, Masatou; Hasegawa, Masataka

2013-01-01

The graphene chemical vapour deposition (CVD) technique at substrate temperatures around 300 °C by a microwave plasma sustained by surface waves (surface wave plasma chemical vapour deposition, SWP-CVD) is discussed. A low-temperature, large-area and high-deposition-rate CVD process for graphene films was developed. It was found from Raman spectra that the deposited films on copper (Cu) substrates consisted of high-quality graphene flakes. The fabricated graphene transparent conductive electrode showed uniform optical transmittance and sheet resistance, which suggests the possibility of graphene for practical electrical and optoelectronic applications. It is intriguing that graphene was successfully deposited on aluminium (Al) substrates, for which we did not expect the catalytic effect to decompose hydrocarbon and hydrogen molecules. We developed a roll-to-roll SWP-CVD system for continuous graphene film deposition towards industrial mass production. A pair of winder and unwinder systems of Cu film was installed in the plasma CVD apparatus. Uniform Raman spectra were confirmed over the whole width of 297 mm of Cu films. We successfully transferred the deposited graphene onto PET films, and confirmed a transmittance of about 95% and a sheet resistance of less than 7 × 10 5 Ω/sq.

Low-temperature graphene synthesis using microwave plasma CVD

Science.gov (United States)

Yamada, Takatoshi; Kim, Jaeho; Ishihara, Masatou; Hasegawa, Masataka

2013-02-01

The graphene chemical vapour deposition (CVD) technique at substrate temperatures around 300 °C by a microwave plasma sustained by surface waves (surface wave plasma chemical vapour deposition, SWP-CVD) is discussed. A low-temperature, large-area and high-deposition-rate CVD process for graphene films was developed. It was found from Raman spectra that the deposited films on copper (Cu) substrates consisted of high-quality graphene flakes. The fabricated graphene transparent conductive electrode showed uniform optical transmittance and sheet resistance, which suggests the possibility of graphene for practical electrical and optoelectronic applications. It is intriguing that graphene was successfully deposited on aluminium (Al) substrates, for which we did not expect the catalytic effect to decompose hydrocarbon and hydrogen molecules. We developed a roll-to-roll SWP-CVD system for continuous graphene film deposition towards industrial mass production. A pair of winder and unwinder systems of Cu film was installed in the plasma CVD apparatus. Uniform Raman spectra were confirmed over the whole width of 297 mm of Cu films. We successfully transferred the deposited graphene onto PET films, and confirmed a transmittance of about 95% and a sheet resistance of less than 7 × 105 Ω/sq.

Rare-earth doped boron nitride nanotubes: Synthesis and characterization

Energy Technology Data Exchange (ETDEWEB)

Silva, Wellington Marcos; Sousa, Edesia Martins Barros de, E-mail: wellingtonmarcos@yahoo.com.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2016-07-01

Full text: Boron nitride is a heat and chemically resistant refractory compound of boron and nitrogen atoms with the chemical formula BN. This structure exists in various crystalline forms that are isoelectronic to a similarly structured carbon lattice. The hexagonal form (h-BN) corresponding to graphite is the most stable and soft among BN polymorph. However, boron nitride nanotubes (BNNTs) were first time synthesized in 1995 [1] and have a type of one-dimensional (1D) nanostructure. Recently the BNNTs have attracted significant interest for scientific and technological applications due to their Wide bandgap. The Wide-bandgap semiconductors doped with rare-earth are considered as a new type of luminescent material, combining special Wide bandgap semiconducting properties with the rare-earth luminescence feature. BNNTs have a stable wide bandgap of 5.5 eV and super thermal and chemical stabilities, which make BNNTs an ideal nanosized luminescent material [2]. In this study, we report a simple and efficient route for the synthesis of BNNTs doped with samarium and europium. High quality BNNTs doped was produced via CVD technique using NH{sub 3} and N{sub 2} gases as source. Boron amorphous, catalyst and oxides rare-earth powder were used as precursor. Detailed studies involving energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and transmission electron microscope (TEM) were performed in order to characterize the BNNTs as grown. [1] Chopra, N. G.; Luyken, R. J. et al. Science, v. 269, p. 966-967, 1995. [2] Chen, H.; Chen, Y. et al. Adv. Matter. v. 19, p. 1845-1848, 2007. (author)

Rare-earth doped boron nitride nanotubes: Synthesis and characterization

International Nuclear Information System (INIS)

Silva, Wellington Marcos; Sousa, Edesia Martins Barros de

2016-01-01

Full text: Boron nitride is a heat and chemically resistant refractory compound of boron and nitrogen atoms with the chemical formula BN. This structure exists in various crystalline forms that are isoelectronic to a similarly structured carbon lattice. The hexagonal form (h-BN) corresponding to graphite is the most stable and soft among BN polymorph. However, boron nitride nanotubes (BNNTs) were first time synthesized in 1995 [1] and have a type of one-dimensional (1D) nanostructure. Recently the BNNTs have attracted significant interest for scientific and technological applications due to their Wide bandgap. The Wide-bandgap semiconductors doped with rare-earth are considered as a new type of luminescent material, combining special Wide bandgap semiconducting properties with the rare-earth luminescence feature. BNNTs have a stable wide bandgap of 5.5 eV and super thermal and chemical stabilities, which make BNNTs an ideal nanosized luminescent material [2]. In this study, we report a simple and efficient route for the synthesis of BNNTs doped with samarium and europium. High quality BNNTs doped was produced via CVD technique using NH 3 and N 2 gases as source. Boron amorphous, catalyst and oxides rare-earth powder were used as precursor. Detailed studies involving energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and transmission electron microscope (TEM) were performed in order to characterize the BNNTs as grown. [1] Chopra, N. G.; Luyken, R. J. et al. Science, v. 269, p. 966-967, 1995. [2] Chen, H.; Chen, Y. et al. Adv. Matter. v. 19, p. 1845-1848, 2007. (author)

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)

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.

High quality single atomic layer deposition of hexagonal boron nitride on single crystalline Rh(111) four-inch wafers

Energy Technology Data Exchange (ETDEWEB)

Hemmi, A.; Bernard, C.; Cun, H.; Roth, S.; Klöckner, M.; Kälin, T.; Osterwalder, J.; Greber, T., E-mail: greber@physik.uzh.ch [Physik-Institut, Universität Zürich, CH-8057 Zürich (Switzerland); Weinl, M.; Gsell, S.; Schreck, M. [Institut für Physik, Universität Augsburg, D-86135 Augsburg (Germany)

2014-03-15

The setup of an apparatus for chemical vapor deposition (CVD) of hexagonal boron nitride (h-BN) and its characterization on four-inch wafers in ultra high vacuum (UHV) environment is reported. It provides well-controlled preparation conditions, such as oxygen and argon plasma assisted cleaning and high temperature annealing. In situ characterization of a wafer is accomplished with target current spectroscopy. A piezo motor driven x-y stage allows measurements with a step size of 1 nm on the complete wafer. To benchmark the system performance, we investigated the growth of single layer h-BN on epitaxial Rh(111) thin films. A thorough analysis of the wafer was performed after cutting in atmosphere by low energy electron diffraction, scanning tunneling microscopy, and ultraviolet and X-ray photoelectron spectroscopies. The apparatus is located in a clean room environment and delivers high quality single layers of h-BN and thus grants access to large area UHV processed surfaces, which had been hitherto restricted to expensive, small area single crystal substrates. The facility is versatile enough for customization to other UHV-CVD processes, e.g., graphene on four-inch wafers.

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

Test of radiation hardness of pcCVD detectors

Energy Technology Data Exchange (ETDEWEB)

Schlemme, Steffen [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Technische Universitaet Darmstadt (Germany); Enders, Joachim [Technische Universitaet Darmstadt (Germany); Figuera, P.; Salamone, S. [LNS-INFN Catania (Italy); Fruehauf, J.; Kis, Mladen; Kratz, A.; Kurz, N.; Loechner, S.; Nociforo, Chiara; Schirru, Fabio; Szczepanczyk, B.; Traeger, M.; Visinka, R. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Musumarra, A. [LNS-INFN Catania (Italy); University of Catania (Italy)

2016-07-01

The new in-flight separator Super-FRS is under construction at the Facility for Antiproton and Ion Research (FAIR, Darmstadt). Ion rates up to 3 x 10{sup 11} {sup 238}U/spill demand an adaption of detectors to a high radiation environment. A test experiment to investigate the radiation hardness of polycrystalline diamond detectors (pcCVD) was performed at the LNS-INFN in Catania using a {sup 12}C beam at 62 MeV/u and intensities of up to 1.5 pnA. The setup consisted of pcCVD strip detectors to measure the beam profile, a single crystal diamond detector to calibrate the ionisation chamber working in current mode as a beam intensity monitor and a pcCVD sample to be irradiated. The IC used was designed for FAIR and showed a stable counting rate allowing us to calibrate and perform beam intensity measurements with it. The total measured counts on the sample were 8.25 x 10{sup 11} counts/mm{sup 2} over a period of 60 hours. Digital waveforms of the pcCVD signals were taken with an oscilloscope and analysed. The results showed no change of the pcCVD signal properties during the entire irradiation.

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.

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)

One-step synthesis of continuous free-standing Carbon Nanotubes-Titanium oxide composite films as anodes for lithium-ion batteries

International Nuclear Information System (INIS)

Gao, Hongxu; Hou, Feng; Wan, Zhipeng; Zhao, Sha; Yang, Deming; Liu, Jiachen; Guo, Anran; Gong, Yuxuan

2015-01-01

Highlights: • CNTs/TiO 2 compoiste films synthesized are continuous and free-standing. • The film can be directly used as flexible, binder-free Lithium-Ion Battery electrode. • The CNTs/TiO 2 electrodes exhibit excellent rate capacity and cyclic stability. • Our strategy is readily applicable to fabricate other CNTs-based composite films. - Abstract: Continuous free-standing Carbon Nanotubes (CNTs)/Titanium oxide (TiO 2 ) composite films were fabricated in a vertical CVD gas flow reactor with water sealing by the One-Step Chemical Vapor Deposition (CVD) approach. The composite films consist of multiple layers of conductive carbon nanotube networks with titanium oxide nanoparticles decorating on carbon nanotube surface. The as-synthesized flexible and transferrable composite films show excellent electrochemical properties, when the content of tetrabutyl titanate is 19.0 wt.%, which can be promising as binder-free anodes for Lithium-Ion Battery (LIB) applications. It demonstrates remarkably high rate capacity of 150 mAh g −1 , as well as excellent high rate cyclic stability over 500 cycles (current density of 3000 mA g −1 ). Such observations can be attributed to the relatively larger surface area and pore volume comparing with pristine CNT films. Great potentials of CNTs/TiO 2 composite films for large-scale production and application in energy devices were shown

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

Effective Duration of Gas Nitriding Process on AISI 316L for the Formation of a Desired Thickness of Surface Nitrided Layer

Directory of Open Access Journals (Sweden)

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.

A CVD diamond beam telescope for charged particle tracking

CERN Document Server

Adam, W; Bergonzo, P; de Boer, Wim; Bogani, F; Borchi, E; Brambilla, A; Bruzzi, Mara; Colledani, C; Conway, J; D'Angelo, P; Dabrowski, W; Delpierre, P A; Dulinski, W; Doroshenko, J; Doucet, M; van Eijk, B; Fallou, A; Fischer, P; Fizzotti, F; Kania, D R; Gan, K K; Grigoriev, E; Hallewell, G D; Han, S; Hartjes, F G; Hrubec, Josef; Husson, D; Kagan, H; Kaplon, J; Kass, R; Keil, M; Knöpfle, K T; Koeth, T W; Krammer, Manfred; Meuser, S; Lo Giudice, A; MacLynne, L; Manfredotti, C; Meier, D; Menichelli, D; Mishina, M; Moroni, L; Noomen, J; Oh, A; Pan, L S; Pernicka, Manfred; Perera, L P; Riester, J L; Roe, S; Rudge, A; Russ, J; Sala, S; Sampietro, M; Schnetzer, S; Sciortino, S; Stelzer, H; Stone, R; Suter, B; Trischuk, W; Tromson, D; Vittone, E; Weilhammer, Peter; Wermes, N; Wetstein, M; Zeuner, W; Zöller, M

2002-01-01

CVD diamond is a radiation hard sensor material which may be used for charged particle tracking near the interaction region in experiments at high luminosity colliders. The goal of the work described here is to investigate the use of several detector planes made of CVD diamond strip sensors for charged particle tracking. Towards this end a tracking telescope composed entirely of CVD diamond planes has been constructed. The telescope was tested in muon beams and its tracking capability has been investigated.

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

Verification of thermo-fluidic CVD reactor model

International Nuclear Information System (INIS)

Lisik, Z; Turczynski, M; Ruta, L; Raj, E

2014-01-01

Presented paper describes the numerical model of CVD (Chemical Vapour Deposition) reactor created in ANSYS CFX, whose main purpose is the evaluation of numerical approaches used to modelling of heat and mass transfer inside the reactor chamber. Verification of the worked out CVD model has been conducted with measurements under various thermal, pressure and gas flow rate conditions. Good agreement between experimental and numerical results confirms correctness of the elaborated model.

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

JPRS Report, Science & Technology, China

Science.gov (United States)

1988-11-10

Plasma-Enhanced CVD Silicon Nitride as Antirefleetion Coating for Silicon Solar Cells 40090008f Beijing TAIYANGNENG XUEBAO [ACTA ENERGIAE SOLARIS SINICA...al.; TAIYANGNENG XUEBAO, No 3, Jul 88] 52 Plasma-Enhanced CVD Silicon Nitride as Antireflection Coating for Silicon Solar Cells [Mao Ganru, et al...130 First Fiber-Optic Line in Jiangxi 130 Solar Power Supply for Fiber-Optic Lines 130 Birefringent Single-Mode Optical Fiber 131 Nanchang

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.

Surface coatings deposited by CVD and PVD

International Nuclear Information System (INIS)

Gabriel, H.M.

1982-01-01

The demand for wear and corrosion protective coatings is increasing due to economic facts. Deposition processes in gas atmospheres like the CVD and PVD processes attained a tremendous importance especially in the field of the deposition of thin hard refractory and ceramic coatings. CVD and PVD processes are reviewed in detail. Some examples of coating installations are shown and numerous applications are given to demonstrate the present state of the art. (orig.) [de

Evaluation of CVD silicon carbide for synchrotron radiation mirrors

International Nuclear Information System (INIS)

Takacs, P.Z.

1981-07-01

Chemical vapor deposited silicon carbide (CVD SiC) is a recent addition to the list of materials suitable for use in the harsh environment of synchrotron radiation (SR) beam lines. SR mirrors for use at normal incidence must be ultrahigh vacuum compatible, must withstand intense x-ray irradiation without surface damage, must be capable of being polished to an extremely smooth surface finish, and must maintain surface figure under thermal loading. CVD SiC exceeds the performance of conventional optical materials in all these areas. It is, however, a relatively new optical material. Few manufacturers have experience in producing optical quality material, and few opticians have experience in figuring and polishing the material. The CVD material occurs in a variety of forms, sensitively dependent upon reaction chamber production conditions. We are evaluating samples of CVD SiC obtained commercially from various manufacturers, representing a range of deposition conditions, to determine which types of CVD material are most suitable for superpolishing. At the time of this writing, samples are being polished by several commercial vendors and surface finish characteristics are being evaluated by various analytical methods

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

Cardiovascular disease (CVD and chronic kidney disease (CKD event rates in HIV-positive persons at high predicted CVD and CKD risk: A prospective analysis of the D:A:D observational study.

Directory of Open Access Journals (Sweden)

Mark A Boyd

2017-11-01

Full Text Available The Data Collection on Adverse Events of Anti-HIV Drugs (D:A:D study has developed predictive risk scores for cardiovascular disease (CVD and chronic kidney disease (CKD, defined as confirmed estimated glomerular filtration rate [eGFR] ≤ 60 ml/min/1.73 m2 events in HIV-positive people. We hypothesized that participants in D:A:D at high (>5% predicted risk for both CVD and CKD would be at even greater risk for CVD and CKD events.We included all participants with complete risk factor (covariate data, baseline eGFR > 60 ml/min/1.73 m2, and a confirmed (>3 months apart eGFR 1%-5%, >5% and fitted Poisson models to assess whether CVD and CKD risk group effects were multiplicative. A total of 27,215 participants contributed 202,034 person-years of follow-up: 74% male, median (IQR age 42 (36, 49 years, median (IQR baseline year of follow-up 2005 (2004, 2008. D:A:D risk equations predicted 3,560 (13.1% participants at high CVD risk, 4,996 (18.4% participants at high CKD risk, and 1,585 (5.8% participants at both high CKD and high CVD risk. CVD and CKD event rates by predicted risk group were multiplicative. Participants at high CVD risk had a 5.63-fold (95% CI 4.47, 7.09, p < 0.001 increase in CKD events compared to those at low risk; participants at high CKD risk had a 1.31-fold (95% CI 1.09, 1.56, p = 0.005 increase in CVD events compared to those at low risk. Participants' CVD and CKD risk groups had multiplicative predictive effects, with no evidence of an interaction (p = 0.329 and p = 0.291 for CKD and CVD, respectively. The main study limitation is the difference in the ascertainment of the clinically defined CVD endpoints and the laboratory-defined CKD endpoints.We found that people at high predicted risk for both CVD and CKD have substantially greater risks for both CVD and CKD events compared with those at low predicted risk for both outcomes, and compared to those at high predicted risk for only CVD or CKD events. This suggests that CVD and

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)

TiO2 anatase thin films deposited by spray pyrolysis of an aerosol of titanium diisopropoxide

International Nuclear Information System (INIS)

Conde-Gallardo, A.; Guerrero, M.; Castillo, N.; Soto, A.B.; Fragoso, R.; Cabanas-Moreno, J.G.

2005-01-01

Titanium dioxide thin films were deposited on crystalline silicon (100) and fused quartz substrates by spray pyrolysis (SP) of an aerosol, generated ultrasonically, of titanium diisopropoxide. The evolution of the crystallization, studied by X-ray diffraction (XRD), atomic force (AFM) and scanning electron microscopy (SEM), reflection and transmission spectroscopies, shows that the deposition process is nearly close to the classical chemical vapor deposition (CVD) technique, producing films with smooth surface and good crystalline properties. At deposition temperatures below 400 deg. C, the films grow in amorphous phase with a flat surface (roughness∼0.5 nm); while for equal or higher values to this temperature, the films develop a crystalline phase corresponding to the TiO 2 anatase phase and the surface roughness is increased. After annealing at 750 deg. C, the samples deposited on Si show a transition to the rutile phase oriented in (111) direction, while for those films deposited on fused quartz no phase transition is observed

Experiment and equipment of depositing diamond films with CVD system

International Nuclear Information System (INIS)

Xie Erqing; Song Chang'an

2002-01-01

CVD (chemical vapor deposition) emerged in recent years is a new technique for thin film deposition, which play a key role in development of modern physics. It is important to predominate the principle and technology of CVD for studying modern physics. In this paper, a suit of CVD experimental equipment for teaching in college physics is presented, which has simple design and low cost. The good result was gained in past teaching practices

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

Application of Cat-CVD for ULSI technology

International Nuclear Information System (INIS)

Akasaka, Yoichi

2008-01-01

The ULSI technology has been following Moore's law into the sub-100 nm era, although several challenging technical issues must be resolved. This paper describes possible application of Cat-CVD for ULSI technology beyond the 45 nm node. Especially, Cat-CVD SiN film for a transistor gate sidewall and/or a pre-metallic liner layer, and removal of photo resist (ash) by Cat-induced hydrogen atoms in the interconnect structure with an extreme low-k material are mainly discussed

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

Ballistic Josephson junctions based on CVD graphene

Science.gov (United States)

Li, Tianyi; Gallop, John; Hao, Ling; Romans, Edward

2018-04-01

Josephson junctions with graphene as the weak link between superconductors have been intensely studied in recent years, with respect to both fundamental physics and potential applications. However, most of the previous work was based on mechanically exfoliated graphene, which is not compatible with wafer-scale production. To overcome this limitation, we have used graphene grown by chemical vapour deposition (CVD) as the weak link of Josephson junctions. We demonstrate that very short, wide CVD-graphene-based Josephson junctions with Nb electrodes can work without any undesirable hysteresis in their electrical characteristics from 1.5 K down to a base temperature of 320 mK, and their gate-tuneable critical current shows an ideal Fraunhofer-like interference pattern in a perpendicular magnetic field. Furthermore, for our shortest junctions (50 nm in length), we find that the normal state resistance oscillates with the gate voltage, consistent with the junctions being in the ballistic regime, a feature not previously observed in CVD-graphene-based Josephson junctions.

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

Ultrathin, wafer-scale hexagonal boron nitride on dielectric surfaces by diffusion and segregation mechanism

Science.gov (United States)

Sonde, Sushant; Dolocan, Andrei; Lu, Ning; Corbet, Chris; Kim, Moon J.; Tutuc, Emanuel; Banerjee, Sanjay K.; Colombo, Luigi

2017-06-01

Chemical vapor deposition (CVD) of two-dimensional (2D) hexagonal boron nitride (h-BN) is at the center of numerous studies for its applications in novel electronic devices. However, a clear understanding of the growth mechanism is lacking for its wider industrial adoption on technologically relevant substrates such as SiO2. Here, we demonstrate a controllable growth method of thin, wafer scale h-BN films on arbitrary substrates. We also clarify the growth mechanism to be diffusion and surface segregation (D-SS) of boron (B) and nitrogen (N) in Ni and Co thin films on SiO2/Si substrates after exposure to diborane and ammonia precursors at high temperature. The segregation was found to be independent of the cooling rates employed in this report, and to our knowledge has not been found nor reported for 2D h-BN growth so far, and thus provides an important direction for controlled growth of h-BN. This unique segregation behavior is a result of a combined effect of high diffusivity, small film thickness and the inability to achieve extremely high cooling rates in CVD systems. The resulting D-SS h-BN films exhibit excellent electrical insulating behavior with an optical bandgap of about 5.8 eV. Moreover, graphene-on-h-BN field effect transistors using the as-grown D-SS h-BN films show a mobility of about 6000 cm2 V-1 s-1 at room temperature.

CVD and obesity in transitional Syria: a perspective from the Middle East.

Science.gov (United States)

Barakat, Hani; Barakat, Hanniya; Baaj, Mohamad K

2012-01-01

Syria is caught in the middle of a disruptive nutritional transition. Its healthcare system is distracted by challenges and successes in other areas while neglecting to address the onslaught of Syria's cardiovascular disease (CVD) epidemic. Despite the official viewpoint touting improvement in health indicators, current trends jeopardize population health, and several surveys in the Syrian population signal the epidemic spreading far and wide. The goal is to counteract the indifference towards obesity as a threat to Syrian's health, as the country is slowly becoming a leader in CVD mortality globally. PubMed, World Health Organization, and official government websites were searched for primary surveys in Syria related to CVD morbidity, mortality, and risk factors. Inclusion criteria ensured that results maximized relevance while producing comparable studies. Statistical analysis was applied to detect the most common risk factor and significant differences in risk factor prevalence and CVD rates. Obesity remained the prevailing CVD risk factor except in older Syrian men, where smoking and hypertension were more common. CVD mortality was more common in males due to coronary disease, while stroke dominated female mortality. The young workforce is especially impacted, with 50% of CVD mortality occurring before age 65 years and an 81% prevalence of obesity in women over 45 years. Syria can overcome its slow response to the CVD epidemic and curb further deterioration by reducing obesity and, thus, inheritance and clustering of risk factors. This can be achieved via multilayered awareness and intensive parental and familial involvement. Extinguishing the CVD epidemic is readily achievable as demonstrated in other countries.

Investigation of defects in CVD diamond: Influence for radiotherapy applications

International Nuclear Information System (INIS)

Guerrero, M.J.; Tromson, D.; Bergonzo, P.; Barrett, R.

2005-01-01

In this study we present the potentialities of CVD diamond as an ionisation chamber for radiotherapy applications. Trapping levels present in CVD diamond are characterised using Thermally Stimulated Current (TSC) method with X-ray sources. The influence of the corresponding defects on the detector response is investigated and compared to those observed in natural diamond. Also, their spatial distribution across a large area polycrystalline diamond ionisation chamber is discussed. Results show the relative influence of two different populations of trapping levels in CVD diamond whose effect is crucial for radiotherapy applications. To partially overcome the defect detrimental effects, we propose to use CVD diamond ionisation chambers at moderate temperatures from 70 to 100 deg. C that could be provided by self heating of the device, for a dramatically improved stability and reproducibility

The formation of tritium permeation barriers by CVD

International Nuclear Information System (INIS)

Forcey, K.S.; Perujo, A.; Reiter, F.; Lolli-Ceroni, P.L.

1993-01-01

The effectiveness as permeation barriers of the following CVD coatings have been investigated: TiC (1 to 2 μm in thickness); a bi-layer of TiN on TiC (3 μm total thickness) and CVD Al 2 O 3 on a TiN/TiC bi-layer. The substrate materials were TZM (a Mo alloy) and 316L stainless steel in the form of discs of diameter 48 mm and thickness 0.1 or 1 mm. Permeation measurements were performed in the temperature range 515-742 K using deuterium at pressures in the range 1-50 kPa. CVD layers were shown to form reasonably effective permeation barriers. At a temperature of 673 K TiC is around 6000 times less permeable to deuterium than 316L stainless steel. (orig.)

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

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.

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

Validation of a model to investigate the effects of modifying cardiovascular disease (CVD) risk factors on the burden of CVD: the rotterdam ischemic heart disease and stroke computer simulation (RISC) model.

Science.gov (United States)

van Kempen, Bob J H; Ferket, Bart S; Hofman, Albert; Steyerberg, Ewout W; Colkesen, Ersen B; Boekholdt, S Matthijs; Wareham, Nicholas J; Khaw, Kay-Tee; Hunink, M G Myriam

2012-12-06

We developed a Monte Carlo Markov model designed to investigate the effects of modifying cardiovascular disease (CVD) risk factors on the burden of CVD. Internal, predictive, and external validity of the model have not yet been established. The Rotterdam Ischemic Heart Disease and Stroke Computer Simulation (RISC) model was developed using data covering 5 years of follow-up from the Rotterdam Study. To prove 1) internal and 2) predictive validity, the incidences of coronary heart disease (CHD), stroke, CVD death, and non-CVD death simulated by the model over a 13-year period were compared with those recorded for 3,478 participants in the Rotterdam Study with at least 13 years of follow-up. 3) External validity was verified using 10 years of follow-up data from the European Prospective Investigation of Cancer (EPIC)-Norfolk study of 25,492 participants, for whom CVD and non-CVD mortality was compared. At year 5, the observed incidences (with simulated incidences in brackets) of CHD, stroke, and CVD and non-CVD mortality for the 3,478 Rotterdam Study participants were 5.30% (4.68%), 3.60% (3.23%), 4.70% (4.80%), and 7.50% (7.96%), respectively. At year 13, these percentages were 10.60% (10.91%), 9.90% (9.13%), 14.20% (15.12%), and 24.30% (23.42%). After recalibrating the model for the EPIC-Norfolk population, the 10-year observed (simulated) incidences of CVD and non-CVD mortality were 3.70% (4.95%) and 6.50% (6.29%). All observed incidences fell well within the 95% credibility intervals of the simulated incidences. We have confirmed the internal, predictive, and external validity of the RISC model. These findings provide a basis for analyzing the effects of modifying cardiovascular disease risk factors on the burden of CVD with the RISC model.

Validation of a model to investigate the effects of modifying cardiovascular disease (CVD risk factors on the burden of CVD: the rotterdam ischemic heart disease and stroke computer simulation (RISC model

Directory of Open Access Journals (Sweden)

van Kempen Bob JH

2012-12-01

Full Text Available Abstract Background We developed a Monte Carlo Markov model designed to investigate the effects of modifying cardiovascular disease (CVD risk factors on the burden of CVD. Internal, predictive, and external validity of the model have not yet been established. Methods The Rotterdam Ischemic Heart Disease and Stroke Computer Simulation (RISC model was developed using data covering 5 years of follow-up from the Rotterdam Study. To prove 1 internal and 2 predictive validity, the incidences of coronary heart disease (CHD, stroke, CVD death, and non-CVD death simulated by the model over a 13-year period were compared with those recorded for 3,478 participants in the Rotterdam Study with at least 13 years of follow-up. 3 External validity was verified using 10 years of follow-up data from the European Prospective Investigation of Cancer (EPIC-Norfolk study of 25,492 participants, for whom CVD and non-CVD mortality was compared. Results At year 5, the observed incidences (with simulated incidences in brackets of CHD, stroke, and CVD and non-CVD mortality for the 3,478 Rotterdam Study participants were 5.30% (4.68%, 3.60% (3.23%, 4.70% (4.80%, and 7.50% (7.96%, respectively. At year 13, these percentages were 10.60% (10.91%, 9.90% (9.13%, 14.20% (15.12%, and 24.30% (23.42%. After recalibrating the model for the EPIC-Norfolk population, the 10-year observed (simulated incidences of CVD and non-CVD mortality were 3.70% (4.95% and 6.50% (6.29%. All observed incidences fell well within the 95% credibility intervals of the simulated incidences. Conclusions We have confirmed the internal, predictive, and external validity of the RISC model. These findings provide a basis for analyzing the effects of modifying cardiovascular disease risk factors on the burden of CVD with the RISC model.

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

Undoped CVD diamond films for electrochemical applications

International Nuclear Information System (INIS)

Mosinska, Lidia; Fabisiak, Kazimierz; Paprocki, Kazimierz; Kowalska, Magdalena; Popielarski, Pawel; Szybowicz, Miroslaw

2013-01-01

By using different deposition conditions, the CVD diamond films with different qualities and orientation were grown by the hot-filament CVD technique. The object of this article is to summarize and discuss relation between structural, physical and electrochemical properties of different diamond electrodes. The physical properties of the Hot Filament CVD microcrystalline diamond films are analyzed by scanning electron microscopy and Raman spectroscopy. In presented studies two different electrodes were used of the diamond grain sizes around 200 nm and 10 μm, as it was estimated from SEM picture. The diamond layers quality was checked on basis of FWHM (Full width at Half Maximum) of 1332 cm −1 diamond Raman peak. The ratio of sp 3 /sp 2 carbon bonds was determined by 1550 cm −1 G band and 1350 cm −1 D band in the Raman spectrum. The electrochemical properties were analyzed using (CV) cyclic voltammetry measurements in aqueous solutions. The sensitivity of undoped diamond electrodes depends strongly on diamond film quality and concentration of amorphous carbon phase in the diamond layer

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

CVD diamond detectors and dosimeters

International Nuclear Information System (INIS)

Manfredotti, C.; Fizzotti, F.; LoGiudice, A.; Paolini, C.; Oliviero, P.; Vittone, E.; Torino Univ., Torino

2002-01-01

Natural diamond, because of its well-known properties of tissue-equivalence, has recorded a wide spreading use in radiotherapy planning with electron linear accelerators. Artificial diamond dosimeters, as obtained by Chemical Vapour Deposition (CVD) could be capable to offer the same performances and they can be prepared in different volumes and shapes. The dosimeter sensitivity per unit volume may be easily proved to be better than standard ionization microchamber. We have prepared in our laboratory CVD diamond microchamber (diamond tips) in emispherical shape with an external diameter of 200 μm, which can be used both as X-ray beam profilometers and as microdosimeters for small field applications like stereotaxy and also for in vivo applications. These dosimeters, which are obtained on a wire substrate that could be either metallic or SiC or even graphite, display good performances also as ion or synchrotron X-rays detectors

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.

Recent results on CVD diamond radiation sensors

Science.gov (United States)

Weilhammer, P.; Adam, W.; Bauer, C.; Berdermann, E.; Bogani, F.; Borchi, E.; Bruzzi, M.; Colledani, C.; Conway, J.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; v. d. Eijk, R.; van Eijk, B.; Fallou, A.; Fish, D.; Fried, M.; Gan, K. K.; Gheeraert, E.; Grigoriev, E.; Hallewell, G.; Hall-Wilton, R.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Kass, R.; Knopfle, K. T.; Krammer, M.; Manfredi, P. F.; Meier, D.; LeNormand; Pan, L. S.; Pernegger, H.; Pernicka, M.; Plano, R.; Re, V.; Riester, J. L.; Roe, S.; Roff; Rudge, A.; Schieber, M.; Schnetzer, S.; Sciortino, S.; Speziali, V.; Stelzer, H.; Stone, R.; Tapper, R. J.; Tesarek, R.; Thomson, G. B.; Trawick, M.; Trischuk, W.; Turchetta, R.; RD 42 Collaboration

1998-02-01

CVD diamond radiation sensors are being developed for possible use in trackers in the LHC experiments. The diamond promises to be radiation hard well beyond particle fluences that can be tolerated by Si sensors. Recent results from the RD 42 collaboration on charge collection distance and on radiation hardness of CVD diamond samples will be reported. Measurements with diamond tracking devices, both strip detectors and pixel detectors, will be discussed. Results from beam tests using a diamond strip detector which was read out with fast, 25 ns shaping time, radiation-hard pipeline electronics will be presented.

Origin, state of the art and some prospects of the diamond CVD

CERN Document Server

Spitsyn, B V; Alexenko, A E

2000-01-01

A short review on the diamond CVD origin, together with its state of the art and some prospects was given. New hybrid methods of the diamond CVD permit to gain 1.2 to 6 times of growth rate in comparison with ordinary diamond CVD's. Recent results on n-type diamond film synthesis through phosphorus doping in the course of the CVD process are briefly discussed. In comparison with high-pressure diamond synthesis, the CVD processes open new facets of the diamond as ultimate crystal for science and technology evolution. It was stressed that, mainly on the basis of new CVDs of diamond, the properties of natural diamond are not only reproduced, but can be surpassed. As examples, mechanical (fracture resistance), physical (thermal conductivity), and chemical (oxidation stability) properties are mentioned. Some present issues in the field are considered.

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.

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.

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).

Selective CVD tungsten on silicon implanted SiO/sub 2/

International Nuclear Information System (INIS)

Hennessy, W.A.; Ghezzo, M.; Wilson, R.H.; Bakhru, H.

1988-01-01

The application range of selective CVD tungsten is extended by its coupling to the ion implantation of insulating materials. This article documents the results of selective CVD tungsten using silicon implanted into SiO/sub 2/ to nucleate the tungsten growth. The role of implant does, energy, and surface preparation in achieving nucleation are described. SEM micrographs are presented to demonstrate the selectivity of this process. Measurements of the tungsten film thickness and sheet resistance are provided for each of the experimental variants corresponding to successful deposition. RBS and XPS analysis are discussed in terms of characterizing the tungsten/oxide interface and to evaluate the role of the silicon implant in the CVD tungsten mechanism. Utilizing this method a desired metallization pattern can be readily defined with lithography and ion implantation, and accurately replicated with a layer of CVD tungsten. This approach avoids problems usually associated with blanket deposition and pattern transfer, which are particularly troublesome for submicron VLSI technology

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 ...

Effects of Light Intensity Activity on CVD Risk Factors: A Systematic Review of Intervention Studies

Directory of Open Access Journals (Sweden)

Romeo B. Batacan

2015-01-01

Full Text Available The effects of light intensity physical activity (LIPA on cardiovascular disease (CVD risk factors remain to be established. This review summarizes the effects of LIPA on CVD risk factors and CVD-related markers in adults. A systematic search of four electronic databases (PubMed, Academic Search Complete, SPORTDiscus, and CINAHL examining LIPA and CVD risk factors (body composition, blood pressure, glucose, insulin, glycosylated hemoglobin, and lipid profile and CVD-related markers (maximal oxygen uptake, heart rate, C-reactive protein, interleukin-6, tumor necrosis factor-alpha, and tumor necrosis factor receptors 1 and 2 published between 1970 and 2015 was performed on 15 March 2015. A total of 33 intervention studies examining the effect of LIPA on CVD risk factors and markers were included in this review. Results indicated that LIPA did not improve CVD risk factors and CVD-related markers in healthy individuals. LIPA was found to improve systolic and diastolic blood pressure in physically inactive populations with a medical condition. Reviewed studies show little support for the role of LIPA to reduce CVD risk factors. Many of the included studies were of low to fair study quality and used low doses of LIPA. Further studies are needed to establish the value of LIPA in reducing CVD risk.

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

Recent results with CVD diamond trackers

Energy Technology Data Exchange (ETDEWEB)

Adam, W.; Bauer, C.; Berdermann, E.; Bergonzo, P.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; Eijk, B. van; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K.K.; Gheeraert, E.; Grigoriev, E.; Hallewell, G.; Hall-Wilton, R.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Karl, C.; Kass, R.; Knoepfle, K.T.; Krammer, M.; Logiudice, A.; Lu, R.; Manfredi, P.F.; Manfredotti, C.; Marshall, R.D.; Meier, D.; Mishina, M.; Oh, A.; Pan, L.S.; Palmieri, V.G.; Pernicka, M.; Peitz, A.; Pirollo, S.; Polesello, P.; Pretzl, K.; Procario, M.; Re, V.; Riester, J.L.; Roe, S.; Roff, D.; Rudge, A.; Runolfsson, O.; Russ, J.; Schnetzer, S.; Sciortino, S.; Speziali, V.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R.J.; Tesarek, R.; Trawick, M.; Trischuk, W.; Vittone, E.; Walsh, A.M.; Wedenig, R.; Weilhammer, P.; White, C.; Ziock, H.; Zoeller, M

1999-08-01

We present recent results on the use of Chemical Vapor Deposition (CVD) diamond microstrip detectors for charged particle tracking. A series of detectors was fabricated using 1 x 1 cm{sup 2} diamonds. Good signal-to-noise ratios were observed using both slow and fast readout electronics. For slow readout electronics, 2 {mu}s shaping time, the most probable signal-to-noise ratio was 50 to 1. For fast readout electronics, 25 ns peaking time, the most probable signal-to-noise ratio was 7 to 1. Using the first 2 x 4 cm{sup 2} diamond from a production CVD reactor with slow readout electronics, the most probable signal-to-noise ratio was 23 to 1. The spatial resolution achieved for the detectors was consistent with the digital resolution expected from the detector pitch.

Recent results with CVD diamond trackers

CERN Document Server

Adam, W; Berdermann, E; Bergonzo, P; Bogani, F; Borchi, E; Brambilla, A; Bruzzi, Mara; Colledani, C; Conway, J; Dabrowski, W; Delpierre, P A; Deneuville, A; Dulinski, W; van Eijk, B; Fallou, A; Fizzotti, F; Foulon, F; Friedl, M; Gan, K K; Gheeraert, E; Grigoriev, E; Hallewell, G D; Hall-Wilton, R; Han, S; Hartjes, F G; Hrubec, Josef; Husson, D; Kagan, H; Kania, D R; Kaplon, J; Karl, C; Kass, R; Knöpfle, K T; Krammer, Manfred; Lo Giudice, A; Lü, R; Manfredi, P F; Manfredotti, C; Marshall, R D; Meier, D; Mishina, M; Oh, A; Pan, L S; Palmieri, V G; Pernicka, Manfred; Peitz, A; Pirollo, S; Polesello, P; Pretzl, Klaus P; Procario, M; Re, V; Riester, J L; Roe, S; Roff, D G; Rudge, A; Runólfsson, O; Russ, J; Schnetzer, S R; Sciortino, S; Speziali, V; Stelzer, H; Stone, R; Suter, B; Tapper, R J; Tesarek, R J; Trawick, M L; Trischuk, W; Vittone, E; Walsh, A M; Wedenig, R; Weilhammer, Peter; White, C; Ziock, H J; Zöller, M

1999-01-01

We present recent results on the use of chemical vapor deposition (CVD) diamond microstrip detectors for charged particle tracking. A series of detectors was fabricated using 1*1 cm/sup 2/ diamonds. Good signal-to-noise ratios were observed using both slow and fast readout electronics. For slow readout electronics, 2 mu s shaping time, the most probable signal-to-noise ratio was 50 to 1. For fast readout electronics, 25 ns peaking time, the most probable signal-to-noise ratio was 7 to 1. Using the first 2*4 cm/sup 2/ diamond from a production CVD reactor with slow readout electronics, the most probable signal-to-noise ratio was 23 to 1. The spatial resolution achieved for the detectors was consistent with the digital resolution expected from the detector pitch. (6 refs).

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....

Friction Properties of Polished Cvd Diamond Films Sliding against Different Metals

Science.gov (United States)

Lin, Zichao; Sun, Fanghong; Shen, Bin

2016-11-01

Owing to their excellent mechanical and tribological properties, like the well-known extreme hardness, low coefficient of friction and high chemical inertness, chemical vapor deposition (CVD) diamond films have found applications as a hard coating for drawing dies. The surface roughness of the diamond films is one of the most important attributes to the drawing dies. In this paper, the effects of different surface roughnesses on the friction properties of diamond films have been experimentally studied. Diamond films were fabricated using hot filament CVD. The WC-Co (Co 6wt.%) drawing dies were used as substrates. A gas mixture of acetone and hydrogen gas was used as the feedstock gas. The CVD diamond films were polished using mechanical polishing. Polished diamond films with three different surface roughnesses, as well as the unpolished diamond film, were fabricated in order to study the tribological performance between the CVD diamond films and different metals with oil lubrication. The unpolished and polished CVD diamond films are characterized with scanning electron microscope (SEM), atomic force microscope (AFM), surface profilometer, Raman spectrum and X-ray diffraction (XRD). The friction examinations were carried out by using a ball-on-plate type reciprocating friction tester. Low carbide steel, stainless steel, copper and aluminum materials were used as counterpart balls. Based on this study, the results presented the friction coefficients between the polished CVD films and different metals. The friction tests demonstrate that the smooth surface finish of CVD diamond films is beneficial for reducing their friction coefficients. The diamond films exhibit low friction coefficients when slid against the stainless steel balls and low carbide steel ball, lower than that slid against copper ball and aluminum ball, attributed to the higher ductility of copper and aluminum causing larger amount of wear debris adhering to the sliding interface and higher adhesive

Changes in CVD risk factors in the activity counseling trial

Directory of Open Access Journals (Sweden)

Meghan Baruth

2011-01-01

Full Text Available Meghan Baruth1, Sara Wilcox1, James F Sallis3, Abby C King4,5, Bess H Marcus6, Steven N Blair1,21Department of Exercise Science, 2Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Public Health Research Center, Columbia, SC, USA; 3Department of Psychology, San Diego State University, San Diego, CA, USA; 4Department of Health Research and Policy, 5Stanford Prevention Research Center, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA; 6Behavioral and Social Sciences Section, Brown University Program in Public Health, Providence, RI, USAAbstract: Primary care facilities may be a natural setting for delivering interventions that focus on behaviors that improve cardiovascular disease (CVD risk factors. The purpose of this study was to examine the 24-month effects of the Activity Counseling Trial (ACT on CVD risk factors, to examine whether changes in CVD risk factors differed according to baseline risk factor status, and to examine whether changes in fitness were associated with changes in CVD risk factors. ACT was a 24-month multicenter randomized controlled trial to increase physical activity. Participants were 874 inactive men and women aged 35–74 years. Participants were randomly assigned to one of three arms that varied by level of counseling, intensity, and resource requirements. Because there were no significant differences in change over time between arms on any of the CVD risk factors examined, all arms were combined, and the effects of time, independent of arm, were examined separately for men and women. Time × Baseline risk factor status interactions examined whether changes in CVD risk factors differed according to baseline risk factor status. Significant improvements in total cholesterol, high-density lipoprotein cholesterol (HDL-C and low-density lipoprotein cholesterol, the ratio of total cholesterol to HDL-C, and triglycerides were seen in

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)

Radiation monitoring with CVD diamonds and PIN diodes at BaBar

Energy Technology Data Exchange (ETDEWEB)

Bruinsma, M. [University of California Irvine, Irvine, CA 92697 (United States); Burchat, P. [Stanford University, Stanford, CA 94305-4060 (United States); Curry, S. [University of California Irvine, Irvine, CA 92697 (United States)], E-mail: scurry@slac.stanford.edu; Edwards, A.J. [Stanford University, Stanford, CA 94305-4060 (United States); Kagan, H.; Kass, R. [Ohio State University, Columbus, OH 43210 (United States); Kirkby, D. [University of California Irvine, Irvine, CA 92697 (United States); Majewski, S.; Petersen, B.A. [Stanford University, Stanford, CA 94305-4060 (United States)

2007-12-11

The BaBar experiment at the Stanford Linear Accelerator Center has been using two polycrystalline chemical vapor deposition (pCVD) diamonds and 12 silicon PIN diodes for radiation monitoring and protection of the Silicon Vertex Tracker (SVT). We have used the pCVD diamonds for more than 3 years, and the PIN diodes for 7 years. We will describe the SVT and SVT radiation monitoring system as well as the operational difficulties and radiation damage effects on the PIN diodes and pCVD diamonds in a high-energy physics environment.

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

Surface structuring of boron doped CVD diamond by micro electrical discharge machining

Science.gov (United States)

Schubert, A.; Berger, T.; Martin, A.; Hackert-Oschätzchen, M.; Treffkorn, N.; Kühn, R.

2018-05-01

Boron doped diamond materials, which are generated by Chemical Vapor Deposition (CVD), offer a great potential for the application on highly stressed tools, e. g. in cutting or forming processes. As a result of the CVD process rough surfaces arise, which require a finishing treatment in particular for the application in forming tools. Cutting techniques such as milling and grinding are hardly applicable for the finish machining because of the high strength of diamond. Due to its process principle of ablating material by melting and evaporating, Electrical Discharge Machining (EDM) is independent of hardness, brittleness or toughness of the workpiece material. EDM is a suitable technology for machining and structuring CVD diamond, since boron doped CVD diamond is electrically conductive. In this study the ablation characteristics of boron doped CVD diamond by micro electrical discharge machining are investigated. Experiments were carried out to investigate the influence of different process parameters on the machining result. The impact of tool-polarity, voltage and discharge energy on the resulting erosion geometry and the tool wear was analyzed. A variation in path overlapping during the erosion of planar areas leads to different microstructures. The results show that micro EDM is a suitable technology for finishing of boron doped CVD diamond.

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.

Lipids, atherosclerosis and CVD risk: is CRP an innocent bystander?

DEFF Research Database (Denmark)

Nordestgaard, B G; Zacho, J

2009-01-01

AIM: To evaluate recent human studies with respect to the interpretation of whether elevated plasma levels of C-reactive protein (CRP) cause cardiovascular disease (CVD), or whether elevated CRP levels more likely is an innocent bystander. DATA SYNTHESIS: Elevated CRP concentrations...... and vulnerability of atherosclerotic plaques, and thus simply an innocent bystander in CVD....

Thermal Analysis of Cold Vacuum Drying (CVD) of Spent Nuclear Fuel (SNF)

International Nuclear Information System (INIS)

PIEPHO, M.G.

2000-01-01

The thermal analysis examined transient thermal and chemical behavior of the Multi-Canister Overpack (MCO) container for a broad range of cases that represent the Cold Vacuum Drying (CVD) processes. The cases were defined to consider both normal and off-normal operations at the CVD Facility for an MCO with N Reactor spent fuel. This analysis provides the basis for the MCO thermal behavior at the CVD Facility in support of the safety basis documentation

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.

Deposition and micro electrical discharge machining of CVD-diamond layers incorporated with silicon

Science.gov (United States)

Kühn, R.; Berger, T.; Prieske, M.; Börner, R.; Hackert-Oschätzchen, M.; Zeidler, H.; Schubert, A.

2017-10-01

In metal forming, lubricants have to be used to prevent corrosion or to reduce friction and tool wear. From an economical and ecological point of view, the aim is to avoid the usage of lubricants. For dry deep drawing of aluminum sheets it is intended to apply locally micro-structured wear-resistant carbon based coatings onto steel tools. One type of these coatings are diamond layers prepared by chemical vapor deposition (CVD). Due to the high strength of diamond, milling processes are unsuitable for micro-structuring of these layers. In contrast to this, micro electrical discharge machining (micro EDM) is a suitable process for micro-structuring CVD-diamond layers. Due to its non-contact nature and its process principle of ablating material by melting and evaporating, it is independent of the hardness, brittleness or toughness of the workpiece material. In this study the deposition and micro electrical discharge machining of silicon incorporated CVD-diamond (Si-CVD-diamond) layers were presented. For this, 10 µm thick layers were deposited on molybdenum plates by a laser-induced plasma CVD process (LaPlas-CVD). For the characterization of the coatings RAMAN- and EDX-analyses were conducted. Experiments in EDM were carried out with a tungsten carbide tool electrode with a diameter of 90 µm to investigate the micro-structuring of Si-CVD-diamond. The impact of voltage, discharge energy and tool polarity on process speed and resulting erosion geometry were analyzed. The results show that micro EDM is a suitable technology for micro-structuring of silicon incorporated CVD-diamond layers.

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.

Cutting characteristics of dental diamond burs made with CVD technology Características de corte de pontas odontológicas diamantadas obtidas pela tecnologia CVD

Directory of Open Access Journals (Sweden)

Luciana Monti Lima

2006-04-01

Full Text Available The aim of this study was to determine the cutting ability of chemical vapor deposition (CVD diamond burs coupled to an ultrasonic dental unit handpiece for minimally invasive cavity preparation. One standard cavity was prepared on the mesial and distal surfaces of 40 extracted human third molars either with cylindrical or with spherical CVD burs. The cutting ability was compared regarding type of substrate (enamel and dentin and direction of handpiece motion. The morphological characteristics, width and depth of the cavities were analyzed and measured using scanning electron micrographs. Statistical analysis using the Kruskal-Wallis test (p O objetivo deste estudo foi determinar a habilidade de corte das pontas de diamante obtidas pelo processo de deposição química a vapor (CVD associadas ao aparelho de ultra-som no preparo cavitário minimamente invasivo. Uma cavidade padronizada foi preparada nas faces mesial e distal de 40 terceiros molares, utilizando-se pontas de diamante CVD cilíndrica e esférica. A habilidade de corte foi comparada quanto ao tipo de substrato (esmalte e dentina e quanto à direção do movimento realizado com a ponta. As características morfológicas, a largura e profundidade das cavidades foram analisadas e medidas em microscopia eletrônica de varredura. A análise estatística pelo teste de Kruskal-Wallis (p < 0,05 revelou que a largura e profundidade das cavidades foram significativamente maiores em dentina. Cavidades mais largas foram obtidas quando se utilizou a ponta de diamante CVD cilíndrica, e mais profundas quando a ponta esférica foi empregada. A direção do movimento da ponta não influenciou o tamanho das cavidades, sendo os cortes produzidos pelas pontas de diamante CVD precisos e conservadores.

Diamond radiation detectors II. CVD diamond development for radiation detectors

International Nuclear Information System (INIS)

Kania, D.R.

1997-01-01

Interest in radiation detectors has supplied some of the impetus for improving the electronic properties of CVD diamond. In the present discussion, we will restrict our attention to polycrystalhne CVD material. We will focus on the evolution of these materials over the past decade and the correlation of detector performance with other properties of the material

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.

Síntesis de materiales cerámicos mediante técnicas químicas en fase vapor (CVD

Directory of Open Access Journals (Sweden)

Gómez-Aleixandre, C.

2003-02-01

Full Text Available Chemical vapour deposition (CVD has been successfully used for the synthesis of a large variety of compounds. Initially the technique was developed for microelectronic applications and then was widespread used for the preparation of hard coatings, optoelectronic and superconductor materials. Among the characteristics inherent to the CVD technique it is worth mentioning the preparation of homogeneous deposits at relatively low temperatures mostly when the reaction is electrically or laser plasma or photon activated. New materials with given characteristics can be produced by properly choosing the reactant gas mixture as well as its relative composition. The presentation will be also focussed onto the deposition of different materials, such as carbon films (both crystalline, and amorphous with diamond-like properties, deposited by plasma assisted CVD techniques using methane and hydrogen gas mixtures. Also, the deposition of binary compounds, as boron nitride will be reviewed. Finally, the experimental requirements for obtaining new ternary compounds from the system Si-B-N-C (i.e.: CBN, SiBN will be discussed. The properties of these materials strongly depend on their composition and structure. Therefore, by adequate selection of the experimental parameters, it is possible to obtain ternary compounds with tailored characteristics.

Actualmente, la técnica de CVD está siendo utilizada en la síntesis de una gran variedad de compuestos cerámicos, generalmente en forma de capa delgada. La técnica, desarrollada inicialmente para su aplicación en microelectrónica, ha sido después utilizada con éxito en otras áreas de gran actividad científica y tecnológica (recubrimientos duros, dispositivos optoelectrónicos, materiales superconductores, etc.. Entre las características más positivas de las técnicas de CVD, cabe destacar la obtención de depósitos homogéneos a temperaturas relativamente bajas, sobre todo cuando la activación de

NEXAFS Study of the Annealing Effect on the Local Structure of FIB-CVD DLC

International Nuclear Information System (INIS)

Saikubo, Akihiko; Kato, Yuri; Igaki, Jun-ya; Kanda, Kazuhiro; Matsui, Shinji; Kometani, Reo

2007-01-01

Annealing effect on the local structure of diamond like carbon (DLC) formed by focused ion beam-chemical vapor deposition (FIB-CVD) was investigated by the measurement of near edge x-ray absorption fine structure (NEXAFS) and energy dispersive x-ray (EDX) spectra. Carbon K edge absorption NEXAFS spectrum of FIB-CVD DLC was measured in the energy range of 275-320 eV. In order to obtain the information on the location of the gallium in the depth direction, incidence angle dependence of NEXAFS spectrum was measured in the incident angle range from 0 deg. to 60 deg. . The peak intensity corresponding to the resonance transition of 1s→σ* originating from carbon-gallium increased from the FIB-CVD DLC annealed at 200 deg. C to the FIB-CVD DLC annealed at 400 deg. C and decreased from that at 400 deg. C to that at 600 deg. C. Especially, the intensity of this peak remarkably enhanced in the NEXAFS spectrum of the FIB-CVD DLC annealed at 400 deg. C at the incident angle of 60 deg. . On the contrary, the peak intensity corresponding to the resonance transition of 1s→π* originating from carbon double bonding of emission spectrum decreased from the FIB-CVD DLC annealed at 200 deg. C to that at 400 deg. C and increased from that at 400 deg. C to that at 600 deg. C. Gallium concentration in the FIB-CVD DLC decreased from ≅2.2% of the as-deposited FIB-CVD DLC to ≅1.5% of the FIB-CVD DLC annealed at 600 deg. C from the elementary analysis using EDX. Both experimental results indicated that gallium atom departed from FIB-CVD DLC by annealing at the temperature of 600 deg. C

Nitride coating enhances endothelialization on biomedical NiTi shape memory alloy

Energy Technology Data Exchange (ETDEWEB)

Ion, Raluca [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095 Bucharest (Romania); Luculescu, Catalin [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, P.O. Box MG-36, 077125 Magurele-Bucharest (Romania); Cimpean, Anisoara, E-mail: anisoara.cimpean@bio.unibuc.ro [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095 Bucharest (Romania); Marx, Philippe [AMF Company, Route de Quincy, 18120 Lury-sur-Arnon (France); Gordin, Doina-Margareta; Gloriant, Thierry [INSA Rennes, UMR CNRS 6226 ISCR, 20 Avenue des Buttes de Coësmes, 35708 Rennes Cedex 7 (France)

2016-05-01

Surface nitriding was demonstrated to be an effective process for improving the biocompatibility of implantable devices. In this study, we investigated the benefits of nitriding the NiTi shape memory alloy for vascular stent applications. Results from cell experiments indicated that, compared to untreated NiTi, a superficial gas nitriding treatment enhanced the adhesion of human umbilical vein endothelial cells (HUVECs), cell spreading and proliferation. This investigation provides data to demonstrate the possibility of improving the rate of endothelialization on NiTi by means of nitride coating. - Highlights: • Gas nitriding process of NiTi is competent to promote cell spreading. • Surface nitriding of NiTi is able to stimulate focal adhesion formation and cell proliferation. • Similar expression pattern of vWf and eNOS was exhibited by bare and nitrided NiTi. • Gas nitriding treatment of NiTi shows promise for better in vivo endothelialization.

Electrochemical behavior of rare earth metals and their nitrides

International Nuclear Information System (INIS)

Ito, Yasuhiko; Goto, Takuya

2004-01-01

Pyrometallurgical recycle process using molten salts is considered to be a high potential in pyro-reprocess technologies for spent nitride fuels, and it is important to understand chemical and electro-chemical behavior of nitrides and metals in molten salts. In this study, cadmium nitrates deposited on the anode Cd plate in motlen salt (LiCl-KCl) with addition of Li 3 N are examined. The cadmium nitrates deposited have various compositions corresponding to polarization potentials and then, the relationship between the deposition potential of nitride Cd and their composition is cleared. Their standard chemical potential of CdN is estimated from electrochemical measurement. And then, potential-pH 3- diagram is drawn by voltametry examination of nitride resolution behavior with using thermochemical data of nitrides. (A. Hishinuma)

Thermodynamics, kinetics and process control of nitriding

DEFF Research Database (Denmark)

Mittemeijer, Eric J.; Somers, Marcel A. J.

1999-01-01

As a prerequisite for predictability of properties obtained by a nitriding treatment of iron-based workpieces, the relation between the process parameters and the composition and structure of the surface layer produced must be known. At present (even) the description of thermodynamic equilibrium...... of pure iron-nitrogen phases has not been achieved fully. It has been shown that taking into account ordering of nitrogen in the epsilon and gamma' iron-nitride phases, leads to an improved understanding of the Fe-N phase diagram. Although thermodynamics indicate the state the system strives for......, the nitriding result is determined largely by the kinetics of the process. The nitriding kinetics have been shown to be characterised by the occurring local near-equilibria and stationary states at surfaces and interfaces, and the diffusion coefficient of nitrogen in the various phases, for which new data have...

A Hybrid Information Mining Approach for Knowledge Discovery in Cardiovascular Disease (CVD

Directory of Open Access Journals (Sweden)

Stefania Pasanisi

2018-04-01

Full Text Available The healthcare ambit is usually perceived as “information rich” yet “knowledge poor”. Nowadays, an unprecedented effort is underway to increase the use of business intelligence techniques to solve this problem. Heart disease (HD is a major cause of mortality in modern society. This paper analyzes the risk factors that have been identified in cardiovascular disease (CVD surveillance systems. The Heart Care study identifies attributes related to CVD risk (gender, age, smoking habit, etc. and other dependent variables that include a specific form of CVD (diabetes, hypertension, cardiac disease, etc.. In this paper, we combine Clustering, Association Rules, and Neural Networks for the assessment of heart-event-related risk factors, targeting the reduction of CVD risk. With the use of the K-means algorithm, significant groups of patients are found. Then, the Apriori algorithm is applied in order to understand the kinds of relations between the attributes within the dataset, first looking within the whole dataset and then refining the results through the subsets defined by the clusters. Finally, both results allow us to better define patients’ characteristics in order to make predictions about CVD risk with a Multilayer Perceptron Neural Network. The results obtained with the hybrid information mining approach indicate that it is an effective strategy for knowledge discovery concerning chronic diseases, particularly for CVD risk.

Residual Stress Induced by Nitriding and Nitrocarburizing

DEFF Research Database (Denmark)

Somers, Marcel A.J.

2005-01-01

The present chapter is devoted to the various mechanisms involved in the buildup and relief of residual stress in nitrided and nitrocarburized cases. The work presented is an overview of model studies on iron and iron-based alloys. Subdivision is made between the compound (or white) layer......, developing at the surfce and consisting of iron-based (carbo)nitrides, and the diffusion zone underneath, consisting of iron and alloying element nitrides dispersed in af ferritic matrix. Microstructural features are related directly to the origins of stress buildup and stres relief....

Ti:Pt:Au:Ni thin-film CVD diamond sensor ability for charged particle detection.

Science.gov (United States)

Kasiwattanawut, Haruetai; Tchouaso, Modeste Tchakoua; Prelas, Mark A

2018-05-22

This work demonstrates the development of diamond sensors with reliable contacts using a new metallization formula, which can operate under high-pressure gas environment. The metallization was created using thin film layers of titanium, platinum, gold and nickel deposited on a single crystal electronic grade CVD diamond chip. The contacts were 2 mm in diameter with thickness of 50/5/20/150 nm of Ti:Pt:Au:Ni. The optimum operating voltage of the sensor was determined from the current-voltage measurements. The sensor was calibrated with 239 Pu and 241 Am alpha radiation sources at 300 V. The energy resolution of the Ti:Pt:Au:Ni diamond sensor was determined to be 7.6% at 5.2 MeV of 239 Pu and 2.2% at 5.48 MeV of 241 Am. The high-pressure gas loading environment under which this sensor was used is discussed. Specifically, experimental observations are described using hydrogen loading of nickel as a means of initiating low energy nuclear reactions. No neutrons, electrons, ions or other ionizing radiations were observed in these experiments. Copyright © 2018 Elsevier Ltd. All rights reserved.

CVD diamond based soft X-ray detector with fast response

International Nuclear Information System (INIS)

Li Fang; Hou Lifei; Su Chunxiao; Yang Guohong; Liu Shenye

2010-01-01

A soft X-ray detector has been made with high quality chemical vapor deposited (CVD) diamond and the electrical structure of micro-strip. Through the measurement of response time on a laser with the pulse width of 10 ps, the full width at half maximum of the data got in the oscilloscope was 115 ps. The rise time of the CVD diamond detector was calculated to be 49 ps. In the experiment on the laser prototype facility, the signal got by the CVD diamond detector was compared with that got by a soft X-ray spectrometer. Both signals coincided well. The detector is proved to be a kind of reliable soft X-ray detector with fast response and high signal-to-noise ratio. (authors)

CVD polycrystalline diamond. A novel neutron detector and applications

International Nuclear Information System (INIS)

Mongkolnavin, R.

1998-01-01

Chemical Vapour Deposition (CVD) Polycrystalline Diamond film has been investigated as a low noise sensor for beta particles, gammas and neutrons using High Energy Physics technologies. Its advantages and disadvantages have been explored in comparison with other particle detectors such as silicon detector and other plastic scintillators. The performance and characteristic of the diamond detector have been fully studied and discussed. These studies will lead to a better understanding of how CVD diamonds perform as a detector and how to improve their performance under various conditions. A CVD diamond detector model has been proposed which is an attempt to explain the behaviour of such an extreme detector material. A novel neutron detector is introduced as a result of these studies. A good thermal and fast neutron detector can be fabricated with CVD diamond with new topologies. This detector will perform well without degradation in a high neutron radiation environment, as diamond is known to be radiation hard. It also offers better neutrons and gammas discrimination for high gamma background applications compared to other semiconductor detectors. A full simulation of the detector has also been done using GEANT, a Monte-Carlo simulation program for particle detectors. Simulation results show that CVD diamond detectors with this novel topology can detect neutrons with great directionality. Experimental work has been done on this detector in a nuclear reactor environment and accelerator source. A novel neutron source which offers a fast pulse high-energy neutrons has also been studied. With this detector, applications in neutron spectrometer for low-Z material have been pursued with various neutron detection techniques. One of these is a low-Z material identification system. The system has been designed and simulated for contraband luggage interrogation using the detector and the novel neutron source. Also other neutron related applications have been suggested. (author)

CVD polycrystalline diamond. A novel neutron detector and applications

International Nuclear Information System (INIS)

Mongkolnavin, R.

1998-07-01

Chemical Vapour Deposition (CVD) Polycrystalline Diamond film has been investigated as a low noise sensor for beta particles, gammas and neutrons using High Energy Physics technologies. Its advantages and disadvantages have been explored in comparison with other particle detectors such as silicon detector and other plastic scintillators. The performance and characteristic of the diamond detector have been fully studied and discussed. These studies will lead to a better understanding of how CVD diamonds perform as a detector and how to improve their performance under various conditions. A CVD diamond detector model has been proposed which is an attempt to explain the behaviour of such an extreme detector material. A novel neutron detector is introduced as a result of these studies. A good thermal and fast neutron detector can be fabricated with CVD diamond with new topologies. This detector will perform well without degradation in a high neutron radiation environment, as diamond is known to be radiation-hard. It also offers better neutrons and gammas discrimination for high gamma background applications compared to other semiconductor detectors. A full simulation of the detector has also been done using GEANT, a Monte Carlo simulation program for particle detectors. Simulation results show that CVD diamond detectors with this novel topology can detect neutrons with great directionality. Experimental work has been done on this detector in a nuclear reactor environment and accelerator source. A novel neutron source which offers a fast pulse high-energy neutrons has also been studied. With this detector, applications in neutron spectrometry for low-Z material have been pursued with various neutron detection techniques. One of these is a low-Z material identification system. The system has been designed and simulated for contraband luggage interrogation using the detector and the novel neutron source. (author)

Layer by layer assembly of catalase and amine-terminated ionic liquid onto titanium nitride nanoparticles modified glassy carbon electrode: Study of direct voltammetry and bioelectrocatalytic activity

International Nuclear Information System (INIS)

Saadati, Shagayegh; Salimi, Abdollah; Hallaj, Rahman; Rostami, Amin

2012-01-01

Highlights: ► Catalase and amine-terminated ionic liquid were immobilized to GC/TiNnp with LBL assembly method. ► First a thin layer of NH 2 -IL is covalently attached to GC/TiNnp electrode using electro-oxidation. ► With alternative assemble of IL and catalase with positive and negative charged, multilayer was formed. ► Immobilized catalase shows excellent electrocatalytic activity toward H 2 O 2 reduction. ► Biosensor response is directly correlated to the number of bilayers. - Abstract: A novel, simple and facile layer by layer (LBL) approach is used for modification of glassy carbon (GC) electrode with multilayer of catalase and nanocomposite containing 1-(3-Aminopropyl)-3-methylimidazolium bromide (amine terminated ionic liquid (NH 2 -IL)) and titanium nitride nanoparticles (TiNnp). First a thin layer of NH 2 -IL is covalently attached to GC/TiNnp electrode using electro-oxidation method. Then, with alternative self assemble positively charged NH 2 -IL and negatively charged catalase a sensitive H 2 O 2 biosensor is constructed, whose response is directly correlated to the number of bilayers. The surface coverage of active catalase per bilayer, heterogeneous electron transfer rate constant (k s ) and Michaelis–Menten constant (K M ) of immobilized catalase were 3.32 × 10 −12 mol cm −2 , 5.28 s −1 and 1.1 mM, respectively. The biosensor shows good stability, high reproducibility, long life-time, and fast amperometric response with the high sensitivity of 380 μA mM −1 cm −2 and low detection limit of 100 nM at concentration range up to 2.1 mM.

Efecto del argon en películas CNxHy depositadas mediante ECR-CVD

Directory of Open Access Journals (Sweden)

Albella, J. M.

2004-04-01

Full Text Available Carbon nitride films have been deposited by ECR-CVD, from Ar/CH4/N2 gas mixtures with different methane concentrations. Infrared Spectroscopy (IRS and Elastic Recoil Detection Analysis (ERDA have been used for films characterisation and Optical Emission Spectroscopy (OES for plasma analysis. Argon concentration in the gas mixture controls the growth rate as well as the composition of the film. In the proposed model, argon plays a key role in the activation of methane molecules. Also, during the growth of the film, two processes may be considered: i Film formation and ii Etching of the growing surface. Changing the gas mixture composition affects both processes, which results in films with different composition and structure as well as different deposition rates.Se ha estudiado el efecto del argon durante el proceso de CVD asistido por un plasma ECR para la síntesis de películas de nitruro de carbono (CNxHy a partir de mezclas gaseosas Ar/CH4/N2 con diferente contenido de metano. Las películas depositadas han sido analizadas mediante espectroscopía infrarroja (IRS y ERDA (Elastic Recoil Detection Analysis, y el análisis del plasma ha sido realizado utilizando la técnica de espectroscopía de emisión óptica (OES. La velocidad de deposición y la composición de las películas depositadas se encuentran determinadas por la concentración de argon en la mezcla gaseosa. Se propone un modelo, según el cual el argon juega un papel fundamental como activador de las moléculas de metano. El modelo propuesto incluye dos procesos simultáneos durante el crecimiento de las capas : i formación de la capa y ii ataque de la superficie de crecimiento. Según la composición de la mezcla gaseosa se favorece uno u otro proceso, lo que conduce a velocidades de deposición diferentes así como a depósitos con diferente composición y estructura atómica.

3D-atom probe analysis of Cr and Cu added nitriding steels

International Nuclear Information System (INIS)

Takahashi, J.; Kawakami, K.; Sugiyama, M.; Kawasaki, K.

2004-01-01

Full text: Nitriding treatment is a very effective method for hardening the surface of steels and realizing improvement in wear-resistance. Although this technology has been performed for many years, the precipitation and hardening mechanisms are not completely clear. It was not easy to observe very fine precipitates which may be generated in nitriding steels. We performed a three-dimensional atom probe analysis of the nitriding steel plate in which two kinds of precipitates were generated. Hot-rolled steel plates, which mainly contained Cr 1.0wt.% and Cu 1.3wt.%, were nitrided by annealing (550-6000 o ) in a mainly NH 3 atmosphere. The material before the nitriding had a hardness of about 100 Hv. By the nitriding, the surface hardness increased to more than 700 Hv, and the inside hardness also increased to 200 Hv. The specimens were taken from 0.15 mm, 0.3 mm and 0.8 mm depth from the surface, which mostly correspond to the peak, the half and the inside hardness, respectively. In the specimen of 0.8 mm depth, prolate spheroidal Cu precipitates of more than 8 nm in diameter were observed. In the specimen of 0.3 mm depth, plate-shape nitride precipitates of 6-10 nm in diameter were observed in addition to the Cu precipitates. Each Cu precipitate made a pair with the nitride precipitate. In the 0.15 mm depth specimen, Cr nitride precipitates of high volume density in addition to the pairs consisting of a Cu precipitate and a Cr nitride precipitate were observed. The size of the nitride precipitate forming the pair was slightly larger than that of the single Cr nitride precipitates. Furthermore, the denuded zone where the nitride precipitate does not exist was observed around the pairs. From these results, it was concluded that three stages of precipitation arose as follows: By the heat treatment of nitriding processing, Cu precipitates were generated first. Then, Cr nitride nucleated at the surface of the Cu precipitates inhomogeneously, and surrounding solute Cr was

Boron nitride hollow nanospheres: Synthesis, formation mechanism and dielectric property

Energy Technology Data Exchange (ETDEWEB)

Zhong, B.; Tang, X.H. [School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, Weihai 264209 (China); Huang, X.X., E-mail: swliza@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Xia, L. [School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, Weihai 264209 (China); Zhang, X.D. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wang, C.J. [School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, Weihai 264209 (China); Wen, G.W., E-mail: g.wen@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, Weihai 264209 (China); School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

2015-04-15

Highlights: • BN hollow nanospheres are fabricated in large scale via a new CVD method. • Morphology and structure are elucidated by complementary analytical techniques. • Formation mechanism is proposed based on experimental observations. • Dielectric properties are investigated in the X-band microwave frequencies. • BN hollow nanospheres show lower dielectric loss than regular BN powders. - Abstract: Boron nitride (BN) hollow nanospheres have been successfully fabricated by pyrolyzing vapors decomposed from ammonia borane (NH{sub 3}BH{sub 3}) at 1300 °C. The final products have been extensively characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The BN hollow nanospheres were ranging from 100 to 300 nm in diameter and around 30–100 nm in thickness. The internal structure of the products was found dependent on the reaction temperatures. A possible formation mechanism of the BN hollow nanospheres was proposed on the basis of the experimental observations. Dielectric measurements in the X-band microwave frequencies (8–12 GHz) showed that the dielectric loss of the paraffin filled by the BN hollow nanospheres was lower than that filled by regular BN powders, which indicated that the BN hollow nanospheres could be potentially used as low-density fillers for microwave radomes.

The Advanced Aluminum Nitride Synthesis Methods and Its Applications: Patent Review.

Science.gov (United States)

Shishkin, Roman A; Elagin, Andrey A; Mayorova, Ekaterina S; Beketov, Askold R

2016-01-01

High purity nanosized aluminum nitride synthesis is a current issue for both industry and science. However, there is no up-to-date review considering the major issues and the technical solutions for different methods. This review aims to investigate the advanced methods of aluminum nitride synthesis and its development tendencies. Also the aluminum nitride application patents and prospects for development of the branch have been considered. The patent search on "aluminum nitride synthesis" has been carried out. The research activity has been analyzed. Special attention has been paid to the patenting geography and the leading researchers in aluminum nitride synthesis. Aluminum nitride synthesis methods have been divided into 6 main groups, the most studied approaches are carbothermal reduction (88 patents) and direct nitridation (107 patents). The current issues for each group have been analyzed; the main trends are purification of the final product and nanopowder synthesis. The leading researchers in aluminum nitride synthesis have represented 5 countries, namely: Japan, China, Russia, South Korea and USA. The main aluminum nitride application spheres are electronics (59,1 percent of applications) and new materials manufacturing (30,9 percent). The review deals with the state of the art data in nanosized aluminum nitride synthesis, the major issues and the technical solutions for different synthesis methods. It gives a full understanding of the development tendencies and of the current leaders in the sphere.

Titanium metal: extraction to application

Energy Technology Data Exchange (ETDEWEB)

Gambogi, Joseph (USGS, Reston, VA); Gerdemann, Stephen J.

2002-09-01

In 1998, approximately 57,000 tons of titanium metal was consumed in the form of mill products (1). Only about 5% of the 4 million tons of titanium minerals consumed each year is used to produce titanium metal, with the remainder primarily used to produce titanium dioxide pigment. Titanium metal production is primarily based on the direct chlorination of rutile to produce titanium tetrachloride, which is then reduced to metal using the Kroll magnesium reduction process. The use of titanium is tied to its high strength-to-weight ratio and corrosion resistance. Aerospace is the largest application for titanium. In this paper, we discuss all aspects of the titanium industry from ore deposits through extraction to present and future applications. The methods of both primary (mining of ore, extraction, and purification) and secondary (forming and machining) operations will be analyzed. The chemical and physical properties of titanium metal will be briefly examined. Present and future applications for titanium will be discussed. Finally, the economics of titanium metal production also are analyzed as well as the advantages and disadvantages of various alternative extraction methods.

Morphological Studies of Local Influence of Implants with Coatings Based on Superhard Compounds on Bone Tissue under Conditions of Induced Trauma

Directory of Open Access Journals (Sweden)

Galimzyan KABIROV

2015-07-01

Full Text Available In this paper we analyze the response of bone tissue to a transosseous introduction of implants made of copper (Cu, medical steel 12X18H9T, steel with nitrides of titanium and hafnium coatings (TiN + HfN, as well as steel coated with titanium and zirconium nitrides (TiN + ZrN into the diaphysis of the tibia of experimental rats. The obtained results showed that the restoration of the injured bone and bone marrow in groups with implants made of steel 12X18H9T occurred without the participation of the granulation and cartilaginous tissues, but with implants made of steel coated with titanium and hafnium nitrides (TiN + HfN, this bone recovery also took place in the early term. At the same time, in groups, where the implants were made of copper (Cu, implants were made of steel coated with titanium and zirconium nitrides (TiN + ZrN were used, such phenomena as necrosis, lysis and destruction of the bone were registered and the bone tissue repair went through formation of the cartilaginous tissue.

Graphene Synthesis by Plasma-Enhanced CVD Growth with Ethanol

OpenAIRE

Campo, T.; Cotto, M.; Márquez, F.; Elizalde, E.; Morant, C.

2016-01-01

A modified route to synthesize graphene flakes is proposed using the Chemical Vapor Deposition (CVD) technique, by using copper substrates as supports. The carbon source used was ethanol, the synthesis temperature was 950°C and the pressure was controlled along the whole process. In this CVD synthesis process the incorporation of the carbon source was produced at low pressure and 950°C inducing the appearance of a plasma blue flash inside the quartz tube. Apparently, the presence of this plas...

Fabrication of Aluminum Gallium Nitride/Gallium Nitride MESFET And It's Applications in Biosensing

Science.gov (United States)

Alur, Siddharth

Gallium Nitride has been researched extensively for the past three decades for its application in Light Emitting Diodes (LED's), power devices and UV photodetectors. With the recent developments in crystal growth technology and the ability to control the doping there has been an increased interest in heterostructures formed between Gallium nitride and it's alloy Aluminium Gallium Nitride. These heterostructures due to the combined effect of spontaneous and piezoelectric effect can form a high density and a high mobility electron gas channel without any intentional doping. This high density electron gas makes these heterostructures ideal to be used as sensors. Gallium Nitride is also chemically very stable. Detection of biomolecules in a fast and reliable manner is very important in the areas of food safety and medical research. For biomolecular detection it is paramount to have a robust binding of the probes on the sensor surface. Therefore, in this dissertation, the fabrication and application of the AlGaN/GaN heterostructures as biological sensors for the detection of DNA and Organophosphate hydrolase enzyme is discussed. In order to use these AlGaN/GaN heterostructures as biological sensors capable of working in a liquid environment photodefinable polydimethyl-siloxane is used as an encapsulant. The immobilization conditions for a robust binding of thiolated DNA and the catalytic receptor enzyme organophosphate hydrolase on gold surfaces is developed with the help of X-ray photoelectron spectroscopy. DNA and OPH are detected by measuring the change in the drain current of the device as a function of time.

Titanium disilicide formation by sputtering of titanium on heated silicon substrate

Science.gov (United States)

Tanielian, M.; Blackstone, S.

1984-09-01

We have sputter deposited titanium on bare silicon substrates at elevated temperatures. We find that at a substrate temperature of about 515 °C titanium silicide is formed due to the reaction of the titanium with the Si. The resistivity of the silicide is about 15 μΩ cm and it is not etchable in a selective titanium etch. This process can have applications in low-temperature, metal-oxide-semiconductor self-aligned silicide formation for very large scale integrated

Flavonoids and Reduction of Cardiovascular Disease (CVD) in Chronic Obstructive Pulmonary Disease (COPD).

Science.gov (United States)

Russo, Patrizia; Prinzi, Giulia; Lamonaca, Palma; Cardaci, Vittorio; Fini, Massimo

2018-05-13

Chronic obstructive pulmonary disease (COPD) and cardiovascular diseases (CV) often coexist. COPD and CVD are complex diseases characterized by a strict interaction between environment and genetic. The mechanisms linking these two diseases are complex, multifactorial and not entirely understood, influencing the therapeutic approach. COPD is characterized by several comorbidities, it is hypothesizable that treatment of cardiovascular co-morbidities may reduce morbidity and mortality. Flavonoids are an important class of plant low molecular weight secondary metabolites (SMs). Convincing data from laboratory, epidemiological, and human clinical studies point to an important effects on CVD risk prevention. This review aims to provide up-to-date information on the ability of Flavonoids to reduce the CVD risk. Current studies support the potential of Flavonoids to prevent the risk of CVD. Well-designed clinical studies are suggested to evaluate advantages and limits of Flavonoids for managing CVD comorbidity in COPD. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Plasma nitriding of CA-6NM steel: effect of H2 + N2 gas mixtures in nitride layer formation for low N2 contents at 500 ºC

Directory of Open Access Journals (Sweden)

Angela Nardelli Allenstein

2010-12-01

Full Text Available This work aims to characterize the phases, thickness, hardness and hardness profiles of the nitride layers formed on the CA-6NM martensitic stainless steel which was plasma nitrided in gas mixtures containing different nitrogen amounts. Nitriding was performed at 500 ºC temperature, and 532 Pa (4 Torr pressure, for gas mixtures of 5% N2 + 95% H2, 10% N2 + 90% H2, and 20% N2 + 80% H2, and 2 hours nitriding time. A 6 hours nitriding time condition for gas mixture of 5% N2 + 95% H2 was also studied. Nitrided samples results were compared with non-nitrided condition. Thickness and microstructure of the nitrided layers were characterized by optical microscopy (OM, using Villela and Nital etchants, and the phases were identified by X-ray diffraction. Hardness profiles and hardness measured on surface steel were determined using Vickers hardness and nanoindentation tester, respectively. It was verified that nitrided layer produced in CA-6NM martensitc stainless steel is constituted of compound layer, being that formation of the diffusion zone was not observed for the studied conditions. The higher the nitrogen amounts in gas mixture the higher is the thickness of the nitrided layer and the probability to form different nitride phases, in the case γ'-Fe4N, ε-Fe2-3N and CrN phases. Intrinsic hardness of the nitrided layers produced in the CA-6NM stainless steel is about 12-14 GPa (~1200-1400 HV.

Ion nitriding in 316=L stainless steel

International Nuclear Information System (INIS)

Rojas-Calderon, E.L.

1989-01-01

Ion nitriding is a glow discharge process that is used to induce surface modification in metals. It has been applied to 316-L austenitic stainless steel looking for similar benefits already obtained in other steels. An austenitic stainless steel was selected because is not hardenable by heat treatment and is not easy to nitride by gas nitriding. The samples were plastically deformed to 10, 20, 40, 50 AND 70% of their original thickness in order to obtain bulk hardening and to observe nitrogen penetration dependence on it. The results were: an increase of one to two rockwell hardness number (except in 70% deformed sample because of its thickness); an increase of even several hundreds per cent in microhardness knoop number in nitrided surface. The later surely modifies waste resistance which would be worth to quantify in further studies. Microhardness measured in an internal transversal face to nitrided surface had a gradual diminish in its value with depth. Auger microanalysis showed a higher relative concentration rate C N /C F e near the surface giving evidence of nitrogen presence till 250 microns deep. The color metallography etchant used, produced faster corrosion in nitrited regions. Therefore, corrosion studies have to be done before using ion nitrited 316-L under these chemicals. (Author)

UN2−x layer formed on uranium metal by glow plasma nitriding

International Nuclear Information System (INIS)

Long, Zhong; Hu, Yin; Chen, Lin; Luo, Lizhu; Liu, Kezhao; Lai, Xinchun

2015-01-01

Highlights: • We used a very simple method to prepare nitride layer on uranium metal surface. • This modified layer is nitrogen-rich nitride, which should be written as UN 2−x . • TEM images show the nitride layer is composed of nano-sized grains. • XPS analysis indicates there is uranium with abnormal low valence in the nitride. - Abstract: Glow plasma nitriding is a simple and economical surface treatment method, and this technology was used to prepare nitride layer on the surface of uranium metal with thickness of several microns. The composition and structure of the nitride layer were analyzed by AES and XRD, indicating that this modified layer is nitrogen-rich uranium nitride, which should be written as UN 2−x . TEM images show the nitride layer is composed of nano-sized grains, with compact structure. And XPS analysis indicates there is uranium with abnormal low valence existing in the nitride. After the treated uranium storage in air for a long time, oxygen just entered the surface several nanometers, showing the nitride layer has excellent oxidation resistance. The mechanism of nitride layer formation and low valence uranium appearance is discussed

Problems and possibilities of development of boron nitride ceramics

International Nuclear Information System (INIS)

Rusanova, L.N.; Romashin, A.G.; Kulikova, G.I.; Golubeva, O.P.

1988-01-01

The modern state of developments in the field of technology of ceramics produced from boron nitride is analyzed. Substantial difficulties in production of pure ceramics from hexagonal and wurtzite-like boron nitride are stated as related to the structure peculiarities and inhomogeneity of chemical bonds in elementary crystal cells of various modifications. Advantages and disadvantages of familiar technological procedures in production of boron nitride ceramics are compared. A new technology is suggested, which is based on the use of electroorganic compounds for hardening and protection of porous high-purity boron-nitride die from oxidation, and as high-efficient sintered elements for treatment of powders of various structures and further pyrolisis. The method is called thermal molecular lacing (TML). Properties of ceramics produced by the TML method are compared with characteristics of well-known brands of boron nitride ceramics

Development of nitride fuel and pyrochemical process for transmutation of minor actinides

International Nuclear Information System (INIS)

Arai, Yasuo; Akabori, Mitsuo; Minato, Kazuo; Uno, Masayoshi

2010-01-01

Nitride fuel cycle for transmutation of minor actinides has been investigated under the double-strata fuel cycle concept. Mononitride solid solutions containing minor actinides have been prepared and characterised. Thermo-physical properties, such as thermal expansion, heat capacity and thermal diffusivity, have been measured by use of minor actinide nitride and burn-up simulated nitride samples. Irradiation behaviour of nitride fuel has been examined by irradiation tests. Pyrochemical process for treatment of spent nitride fuel has been investigated mainly by electrochemical measurements and nitride formation behaviour in pyrochemical process has been studied for recycled fuel fabrication. Recent results of experimental study on nitride fuel and pyrochemical process are summarised in the paper. (authors)

Corrosion fatigue behaviour of ion nitrided AISI 4140 steel

Energy Technology Data Exchange (ETDEWEB)

Genel, K. [Sakarya Univ., Adapazari (Turkey). Mech. Eng. Dept.; Demirkol, M.; Guelmez, T. [Faculty of Mechanical Engineering, Istanbul Technical University, Guemuessuyu, 80191, Istanbul (Turkey)

2000-08-31

Machine components suffer from corrosion degradation of fatigue characteristics and improvement can be attained by the application of a nitriding treatment, particularly to low alloy steels. In the present study, the effect of ion nitriding on corrosion fatigue performance of AISI 4140 steel has been investigated by conducting a series of rotary bending corrosion fatigue tests at 95 Hz, in 3% NaCl aqueous solution. Hourglass shaped, 4 mm diameter fatigue specimens were ion nitrided at 748 K for 1, 3, 8 and 16 h prior to the tests. It was observed that distinct fatigue limit behaviour of ion nitrided steel in air completely disappeared in corrosive environment besides severe degradation in fatigue characteristics. An improvement reaching to 60% in corrosion fatigue strength can be attained by successive ion nitriding practice based on a fatigue life of 10{sup 7} cycles. An attempt was made to establish an empirical relationship between corrosion fatigue strength and relative case depth, which considers the size of the ion nitrided specimen. It was also determined that a power relationship holds between corrosion fatigue strength and fatigue life of ion nitrided steel. The presence of white layer has resulted in additional improvement in corrosion fatigue resistance, and it was observed that corrosion fatigue cracks were initiated dominantly under the white layer by pit formation mechanism. (orig.)

Corrosion fatigue behaviour of ion nitrided AISI 4140 steel

International Nuclear Information System (INIS)

Genel, K.

2000-01-01

Machine components suffer from corrosion degradation of fatigue characteristics and improvement can be attained by the application of a nitriding treatment, particularly to low alloy steels. In the present study, the effect of ion nitriding on corrosion fatigue performance of AISI 4140 steel has been investigated by conducting a series of rotary bending corrosion fatigue tests at 95 Hz, in 3% NaCl aqueous solution. Hourglass shaped, 4 mm diameter fatigue specimens were ion nitrided at 748 K for 1, 3, 8 and 16 h prior to the tests. It was observed that distinct fatigue limit behaviour of ion nitrided steel in air completely disappeared in corrosive environment besides severe degradation in fatigue characteristics. An improvement reaching to 60% in corrosion fatigue strength can be attained by successive ion nitriding practice based on a fatigue life of 10 7 cycles. An attempt was made to establish an empirical relationship between corrosion fatigue strength and relative case depth, which considers the size of the ion nitrided specimen. It was also determined that a power relationship holds between corrosion fatigue strength and fatigue life of ion nitrided steel. The presence of white layer has resulted in additional improvement in corrosion fatigue resistance, and it was observed that corrosion fatigue cracks were initiated dominantly under the white layer by pit formation mechanism. (orig.)

Radiofrequency cold plasma nitrided carbon steel: Microstructural and micromechanical characterizations

International Nuclear Information System (INIS)

Bouanis, F.Z.; Bentiss, F.; Bellayer, S.; Vogt, J.B.; Jama, C.

2011-01-01

Highlights: → C38 carbon steel samples were plasma nitrided using a radiofrequency (rf) nitrogen plasma discharge. → RF plasma treatment enables nitriding for non-heated substrates. → The morphological and chemical analyses show the formation of a uniform thickness on the surface of the nitrided C38 steel. → Nitrogen plasma active species diffuse into the samples and lead to the formation of Fe x N. → The increase in microhardness values for nitrided samples with plasma processing time is interpreted by the formation of a thicker nitrided layer on the steel surface. - Abstract: In this work, C38 carbon steel was plasma nitrided using a radiofrequency (rf) nitrogen plasma discharge on non-heated substrates. General characterizations were performed to compare the chemical compositions, the microstructures and hardness of the untreated and plasma treated surfaces. The plasma nitriding was carried out on non-heated substrates at a pressure of 16.8 Pa, using N 2 gas. Surface characterizations before and after N 2 plasma treatment were performed by means of the electron probe microanalysis (EPMA), X-ray photoelectron spectroscopy (XPS) and Vickers microhardness measurements. The morphological and chemical analysis showed the formation of a uniform structure on the surface of the nitrided sample with enrichment in nitrogen when compared to untreated sample. The thickness of the nitride layer formed depends on the treatment time duration and is approximately 14 μm for 10 h of plasma treatment. XPS was employed to obtain chemical-state information of the plasma nitrided steel surfaces. The micromechanical results show that the surface microhardness increases as the plasma-processing time increases to reach, 1487 HV 0.005 at a plasma processing time of 8 h.

Radiofrequency cold plasma nitrided carbon steel: Microstructural and micromechanical characterizations

Energy Technology Data Exchange (ETDEWEB)

Bouanis, F.Z. [Universite Lille Nord de France, F-59000 Lille (France); Unite Materiaux et Transformations (UMET), Ingenierie des Systemes Polymeres, CNRS UMR 8207, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France); Bentiss, F. [Laboratoire de Chimie de Coordination et d' Analytique, Faculte des Sciences, Universite Chouaib Doukkali, B.P. 20, M-24000 El Jadida (Morocco); Bellayer, S.; Vogt, J.B. [Universite Lille Nord de France, F-59000 Lille (France); Unite Materiaux et Transformations (UMET), Ingenierie des Systemes Polymeres, CNRS UMR 8207, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France); Jama, C., E-mail: charafeddine.jama@ensc-lille.fr [Universite Lille Nord de France, F-59000 Lille (France); Unite Materiaux et Transformations (UMET), Ingenierie des Systemes Polymeres, CNRS UMR 8207, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France)

2011-05-16

Highlights: {yields} C38 carbon steel samples were plasma nitrided using a radiofrequency (rf) nitrogen plasma discharge. {yields} RF plasma treatment enables nitriding for non-heated substrates. {yields} The morphological and chemical analyses show the formation of a uniform thickness on the surface of the nitrided C38 steel. {yields} Nitrogen plasma active species diffuse into the samples and lead to the formation of Fe{sub x}N. {yields} The increase in microhardness values for nitrided samples with plasma processing time is interpreted by the formation of a thicker nitrided layer on the steel surface. - Abstract: In this work, C38 carbon steel was plasma nitrided using a radiofrequency (rf) nitrogen plasma discharge on non-heated substrates. General characterizations were performed to compare the chemical compositions, the microstructures and hardness of the untreated and plasma treated surfaces. The plasma nitriding was carried out on non-heated substrates at a pressure of 16.8 Pa, using N{sub 2} gas. Surface characterizations before and after N{sub 2} plasma treatment were performed by means of the electron probe microanalysis (EPMA), X-ray photoelectron spectroscopy (XPS) and Vickers microhardness measurements. The morphological and chemical analysis showed the formation of a uniform structure on the surface of the nitrided sample with enrichment in nitrogen when compared to untreated sample. The thickness of the nitride layer formed depends on the treatment time duration and is approximately 14 {mu}m for 10 h of plasma treatment. XPS was employed to obtain chemical-state information of the plasma nitrided steel surfaces. The micromechanical results show that the surface microhardness increases as the plasma-processing time increases to reach, 1487 HV{sub 0.005} at a plasma processing time of 8 h.

CVD diamonds as thermoluminescent detectors for medical applications

International Nuclear Information System (INIS)

Marczewska, B.; Olko, P.; Nesladek, M.; Waligorski, M.P.R.; Kerremans, Y.

2002-01-01

Diamond is believed to be a promising material for medical dosimetry due to its tissue equivalence, mechanical and radiation hardness, and lack of solubility in water or in disinfecting agents. A number of diamond samples, obtained under different growth conditions at Limburg University, using the chemical vapour deposition (CVD) technique, was tested as thermoluminescence dosemeters. Their TL glow curve, TL response after doses of gamma rays, fading, and so on were studied at dose levels and for radiation modalities typical for radiotherapy. The investigated CVD diamonds displayed sensitivity comparable with that of MTS-N (Li:Mg,Ti) detectors, signal stability (reproducibility after several readouts) below 10% (1 SD) and no fading was found four days after irradiation. A dedicated CVD diamond plate was grown, cut into 20 detector chips (3x3x0.5 mm) and used for measuring the dose-depth distribution at different depths in a water phantom, for 60 Co and six MV X ray radiotherapy beams. Due to the sensitivity of diamond to ambient light, it was difficult to achieve reproducibility comparable with that of standard LiF detectors. (author)

Defining the relationship between COPD and CVD: what are the implications for clinical practice?

Science.gov (United States)

Morgan, Ann D; Zakeri, Rosita; Quint, Jennifer K

2018-01-01

Cardiovascular diseases (CVDs) are arguably the most important comorbidities in chronic obstructive pulmonary disease (COPD). CVDs are common in people with COPD, and their presence is associated with increased risk for hospitalization, longer length of stay and all-cause and CVD-related mortality. The economic burden associated with CVD in this population is considerable and the cumulative cost of treating comorbidities may even exceed that of treating COPD itself. Our understanding of the biological mechanisms that link COPD and various forms of CVD has improved significantly over the past decade. But despite broad acceptance of the prognostic significance of CVDs in COPD, there remains widespread under-recognition and undertreatment of comorbid CVD in this population. The reasons for this are unclear; however institutional barriers and a lack of evidence-based guidelines for the management of CVD in people with COPD may be contributory factors. In this review, we summarize current knowledge relating to the prevalence and incidence of CVD in people with COPD and the mechanisms that underlie their coexistence. We discuss the implications for clinical practice and highlight opportunities for improved prevention and treatment of CVD in people with COPD. While we advocate more active assessment for signs of cardiovascular conditions across all age groups and all stages of COPD severity, we suggest targeting those aged under 65 years. Evidence indicates that the increased risks for CVD are particularly pronounced in COPD patients in mid-to-late-middle-age and thus it is in this age group that the benefits of early intervention may prove to be the most effective. PMID:29355081

Intrinsic ferromagnetism in hexagonal boron nitride nanosheets

Energy Technology Data Exchange (ETDEWEB)

Si, M. S.; Gao, Daqiang, E-mail: gaodq@lzu.edu.cn, E-mail: xueds@lzu.edu.cn; Yang, Dezheng; Peng, Yong; Zhang, Z. Y.; Xue, Desheng, E-mail: gaodq@lzu.edu.cn, E-mail: xueds@lzu.edu.cn [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Liu, Yushen [Jiangsu Laboratory of Advanced Functional Materials and College of Physics and Engineering, Changshu Institute of Technology, Changshu 215500 (China); Deng, Xiaohui [Department of Physics and Electronic Information Science, Hengyang Normal University, Hengyang 421008 (China); Zhang, G. P. [Department of Physics, Indiana State University, Terre Haute, Indiana 47809 (United States)

2014-05-28

Understanding the mechanism of ferromagnetism in hexagonal boron nitride nanosheets, which possess only s and p electrons in comparison with normal ferromagnets based on localized d or f electrons, is a current challenge. In this work, we report an experimental finding that the ferromagnetic coupling is an intrinsic property of hexagonal boron nitride nanosheets, which has never been reported before. Moreover, we further confirm it from ab initio calculations. We show that the measured ferromagnetism should be attributed to the localized π states at edges, where the electron-electron interaction plays the role in this ferromagnetic ordering. More importantly, we demonstrate such edge-induced ferromagnetism causes a high Curie temperature well above room temperature. Our systematical work, including experimental measurements and theoretical confirmation, proves that such unusual room temperature ferromagnetism in hexagonal boron nitride nanosheets is edge-dependent, similar to widely reported graphene-based materials. It is believed that this work will open new perspectives for hexagonal boron nitride spintronic devices.

Leaching of Titanium and Silicon from Low-Grade Titanium Slag Using Hydrochloric Acid Leaching

Science.gov (United States)

Zhao, Longsheng; Wang, Lina; Qi, Tao; Chen, Desheng; Zhao, Hongxin; Liu, Yahui; Wang, Weijing

2018-05-01

Acid-leaching behaviors of the titanium slag obtained by selective reduction of vanadium-bearing titanomagnetite concentrates were investigated. It was found that the optimal leaching of titanium and silicon were 0.7% and 1.5%, respectively. The titanium and silicon in the titanium slag were firstly dissolved in the acidic solution to form TiO2+ and silica sol, and then rapidly reprecipitated, forming hydrochloric acid (HCl) leach residue. Most of the silicon presented in the HCl leach residue as floccules-like silica gel, while most of the titanium was distributed in the nano-sized rod-like clusters with crystallite refinement and intracrystalline defects, and, as such, 94.3% of the silicon was leached from the HCl leach residue by alkaline desilication, and 96.5% of the titanium in the titanium-rich material with some rutile structure was then digested by the concentrated sulfuric acid. This provides an alternative route for the comprehensive utilization of titanium and silicon in titanium slag.

Development of CVD diamond radiation detectors

CERN Document Server

Adam, W; Berdermann, E; Bogani, F; Borchi, E; Bruzzi, Mara; Colledani, C; Conway, J; Dabrowski, W; Delpierre, P A; Deneuville, A; Dulinski, W; van Eijk, B; Fallou, A; Fisch, D; Foulon, F; Friedl, M; Gan, K K; Gheeraert, E; Grigoriev, E A; Hallewell, G D; Hall-Wilton, R; Han, S; Hartjes, F G; Hrubec, Josef; Husson, D; Kagan, H; Kania, D R; Kaplon, J; Kass, R; Knöpfle, K T; Krammer, Manfred; Manfredi, P F; Meier, D; Mishina, M; Le Normand, F; Pan, L S; Pernegger, H; Pernicka, Manfred; Pirollo, S; Re, V; Riester, J L; Roe, S; Roff, D G; Rudge, A; Schnetzer, S R; Sciortino, S; Speziali, V; Stelzer, H; Stone, R; Tapper, R J; Tesarek, R J; Thomson, G B; Trawick, M L; Trischuk, W; Turchetta, R; Walsh, A M; Wedenig, R; Weilhammer, Peter; Ziock, H J; Zoeller, M M

1998-01-01

Diamond is a nearly ideal material for detecting ionizing radiation. Its outstanding radiation hardness, fast charge collection and low leakage current allow a diamond detector to be used in high ra diation, high temperature and in aggressive chemical media. We have constructed charged particle detectors using high quality CVD diamond. Characterization of the diamond samples and various detect ors are presented in terms of collection distance, $d=\\mu E \\tau$, the average distance electron-hole pairs move apart under the influence of an electric field, where $\\mu$ is the sum of carrier mo bilities, $E$ is the applied electric field, and $\\tau$ is the mobility weighted carrier lifetime. Over the last two years the collection distance increased from $\\sim$ 75 $\\mu$m to over 200 $\\mu$ m. With this high quality CVD diamond a series of micro-strip and pixel particle detectors have been constructed. These devices were tested to determine their position resolution and signal to n oise performance. Diamond detectors w...

Structure and electrochemical properties of plasma-nitrided low alloy steel

Energy Technology Data Exchange (ETDEWEB)

Chyou, S.D.; Shih, H.C. (Dept. of Materials Science and Engineering, National Tsing Hua Univ., Hsinchu (Taiwan))

1990-10-01

Plasma-nitrided SAE 4140 steel has been widely applied industrially because of its superior resistance to wear and fatigue. However, its corrosion behaviour in aqueous environments has not been completely explored. The effects of nitriding on corrosion were investigated by performing electrochemical tests on both nitrided and untreated SAE 4140. It was found that, by plasma nitriding, the corrosion resistance improved significantly in HNO{sub 3} and Na{sub 2}SO{sub 4} aqueous environments. A reaction model is proposed to explain the beneficial effect of nitride on corrosion resistance. It is concluded that nitrogen and chromium (an alloying element) act synergistically to form a dense protective layer which is responsible for the corrosion resistance. Characterization of the surface layers by Auger electron spectroscopy and X-ray photoelectron spectroscopy reveals that the protective layer is composed of (Fe, Cr){sub 4}N, (Fe, Cr){sub 2-3}N and CrN in the inner layer, Fe{sub 2}O{sub 3}, Cr{sub 2}O{sub 3} together with nitrides in the middle layer, and nitrides, {gamma}'-FeOOH, and Cr(OH){sub 3}.H{sub 2}O in the outermost layer. (orig.).

Thermoluminescence properties of undoped diamond films deposited using HF CVD technique

Directory of Open Access Journals (Sweden)

Paprocki K.

2018-03-01

Full Text Available Natural diamond has been considered as a perspective material for clinical radiation dosimetry due to its tissuebiocompatibility and chemical inertness. However, the use of natural diamond in radiation dosimetry has been halted by the high market price. The recent progress in the development of CVD techniques for diamond synthesis, offering the capability of growing high quality diamond layers, has renewed the interest in using this material in radiation dosimeters having small geometricalsizes. Polycrystalline CVD diamond films have been proposed as detectors and dosimeters of β and α radiation with prospective applications in high-energy photon dosimetry. In this work, we present a study on the TL properties of undoped diamond film samples grown by the hot filament CVD (HF CVD method and exposed to β and α radiation. The glow curves for both types of radiation show similar character and can be decomposed into three components. The dominant TL peaks are centered at around 610 K and exhibit activation energy of the order of 0.90 eV.

Titanium and titanium alloys: fundamentals and applications

National Research Council Canada - National Science Library

Leyens, C; Peters, M

2003-01-01

... number of titanium alloys have paved the way for light metals to vastly expand into many industrial applications. Titanium and its alloys stand out primarily due to their high specific strength and excellent corrosion resistance, at just half the weight of steels and Ni-based superalloys. This explains their early success in the aerospace and the...

Atomic Resolution Microscopy of Nitrides in Steel

DEFF Research Database (Denmark)

Danielsen, Hilmar Kjartansson

2014-01-01

MN and CrMN type nitride precipitates in 12%Cr steels have been investigated using atomic resolution microscopy. The MN type nitrides were observed to transform into CrMN both by composition and crystallography as Cr diffuses from the matrix into the MN precipitates. Thus a change from one...

Defects in dilute nitrides

International Nuclear Information System (INIS)

Chen, W.M.; Buyanova, I.A.; Tu, C.W.; Yonezu, H.

2005-01-01

We provide a brief review our recent results from optically detected magnetic resonance studies of grown-in non-radiative defects in dilute nitrides, i.e. Ga(In)NAs and Ga(Al,In)NP. Defect complexes involving intrinsic defects such as As Ga antisites and Ga i self interstitials were positively identified.Effects of growth conditions, chemical compositions and post-growth treatments on formation of the defects are closely examined. These grown-in defects are shown to play an important role in non-radiative carrier recombination and thus in degrading optical quality of the alloys, harmful to performance of potential optoelectronic and photonic devices based on these dilute nitrides. (author)

CVD calibration light systems specifications. Rev. 0

International Nuclear Information System (INIS)

Mcllwain, A. K.

1992-04-01

Two prototype Cerenkov Viewing Device Calibration Light systems for the Mark IV CVD have been fabricated. They consist of a maintenance unit that will be used by the IAEA maintenance staff and a field unit that will be used by IAEA inspectors. More detailed information on the design of the calibration units can be obtained from the document SSP-39 and additional information on the Mark IV CVD can be obtained from the operating manual published as Canadian Safeguards Support Program document CSSP 6. The specifications refer to the prototype units which will be demonstrated to the IAEA in 1992 May. Based upon the feedback from the IAEA, the instruments will be changed in the final production models to provide devices that more closely satisfy the needs of the end users

Synthesis of Titanium Oxycarbide from Titanium Slag by Methane-Containing Gas

Science.gov (United States)

Dang, Jie; Fatollahi-Fard, Farzin; Pistorius, Petrus Christiaan; Chou, Kuo-Chih

2018-02-01

In this study, reaction steps of a process for synthesis of titanium oxycarbide from titanium slag were demonstrated. This process involves the reduction of titanium slag by a methane-hydrogen-argon mixture at 1473 K (1200 °C) and the leaching of the reduced products by hydrofluoric acid near room temperature to remove the main impurity (Fe3Si). Some iron was formed by disproportionation of the main M3O5 phase before gaseous reduction started. Upon reduction, more iron formed first, followed by reduction of titanium dioxide to suboxides and eventually oxycarbide.

Analyses of antibacterial activity and cell compatibility of titanium coated with a Zr-C-N film.

Directory of Open Access Journals (Sweden)

Yin-Yu Chang

Full Text Available The purpose of this study was to verify the antibacterial performance and cell proliferation activity of zirconium (Zr-carbon (C-nitride (N coatings on commercially pure titanium (Ti with different C contents.Reactive nitrogen gas (N(2 with and without acetylene (C(2H(2 was activated by Zr plasma in a cathodic-arc evaporation system to deposit either a zirconium nitride (ZrN or a Zr-C-N coating onto Ti plates. The bacterial activity of the coatings was evaluated against Staphylococcus aureus with the aid of SYTO9 nucleic acid staining and scanning electron microscopy (SEM. Cell compatibility, mRNA expression, and morphology related to human gingival fibroblasts (HGFs on the coated samples were also determined by using the MTT assay, reverse transcriptase-polymerase chain reaction, and SEM.The Zr-C-N coating with the highest C content (21.7 at% exhibited the lowest bacterial preservation (P<0.001. Biological responses including proliferation, gene expression, and attachment of HGF cells to ZrN and Zr-C-N coatings were comparable to those of the uncoated Ti plate.High-C-content Zr-C-N coatings not only provide short-term antibacterial activity against S. aureus but are also biocompatible with HGF cells.

The Effect of Mesoporous Carbon Nitride Modification by Titanium Oxide Nanoparticles on Photocatalytic Degradation of 1,3-Dinitrobenzene

Directory of Open Access Journals (Sweden)

Seyyed Ershad Moradi

2015-11-01

Full Text Available In the present work, well ordered, mesoporous carbon nitride (MCN sorbent with uniform mesoporous wall, high surface area and pore volume has been fabricated using the simple polymerization reaction between ethylene diamine and carbon tetrachloride in mesoporous silica media, and then modified by TiO2 nanoparticles (Ti-MCN. The structural order and textural properties of the nanoporous materials were studied by XRD, elemental analysis, and nitrogen adsorption–desorption experiments. Photodegradation experiments for 1,3-dinitrobenzene were conducted in batch mode, the Ti-MCN catalysts were found to be more active compared to the free TiO2 nanoparticles for 1,3-dinitrobenzene degradation.

Low temperature anodic bonding to silicon nitride

DEFF Research Database (Denmark)

Weichel, Steen; Reus, Roger De; Bouaidat, Salim

2000-01-01

Low-temperature anodic bonding to stoichiometric silicon nitride surfaces has been performed in the temperature range from 3508C to 4008C. It is shown that the bonding is improved considerably if the nitride surfaces are either oxidized or exposed to an oxygen plasma prior to the bonding. Both bu...

Review of actinide nitride properties with focus on safety aspects

Energy Technology Data Exchange (ETDEWEB)

Albiol, Thierry [CEA Cadarache, St Paul Lez Durance Cedex (France); Arai, Yasuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2001-12-01

This report provides a review of the potential advantages of using actinide nitrides as fuels and/or targets for nuclear waste transmutation. Then a summary of available properties of actinide nitrides is given. Results from irradiation experiments are reviewed and safety relevant aspects of nitride fuels are discussed, including design basis accidents (transients) and severe (core disruptive) accidents. Anyway, as rather few safety studies are currently available and as many basic physical data are still missing for some actinide nitrides, complementary studies are proposed. (author)

Microstructure and Hardness of High Temperature Gas Nitrided AISI 420 Martensitic Stainless Steel

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Ibrahim Nor Nurulhuda Md.

2014-07-01

Full Text Available This study examined the microstructure and hardness of as-received and nitrided AISI 420 martensitic stainless steels. High temperature gas nitriding was employed to treat the steels at 1200°C for one hour and four hours using nitrogen gas, followed by furnace cooled. Chromium nitride and iron nitride were formed and concentrated at the outmost surface area of the steels since this region contained the highest concentration of nitrogen. The grain size enlarged at the interior region of the nitrided steels due to nitriding at temperature above the recrystallization temperature of the steel and followed by slow cooling. The nitrided steels produced higher surface hardness compared to as-received steel due to the presence of nitrogen and the precipitation of nitrides. Harder steel was produced when nitriding at four hours compared to one hour since more nitrogen permeated into the steel.

Recent Results from Beam Tests of 3D and Pad pCVD Diamond Detectors

CERN Document Server

Wallny, Rainer

2017-01-01

Results from prototypes of a detector using chemical vapor deposited (CVD) diamond with embedded resistive electrodes in the bulk forming a 3D diamond device are presented. A detector system consisting of 3D devices based on poly-crystalline CVD (pCVD) diamond was connected to a multi-channel readout and successfully tested in a 120 GeV/c proton beam at CERN proving for the first time the feasibility of the 3D detector concept in pCVD for particle tracking applications. We also present beam test results on the dependence of signal size on incident particle rate in charged particle detectors based on poly-crystalline CVD diamond. The detectors were tested in a 260 MeV/c pion beam over a range of particle fluxes from 2 kHz/cm2 to 10 MHz/cm2 . The pulse height of the sensors was measured with pad readout electronics at a peaking time of 7 ns. Our data from the 2015 beam tests at PSI indicate that the pulse height of poly-crystalline CVD diamond sensor irradiated to 5×1014 neq/cm2 is independent of particle flux...

Influence of plastic deformation on nitriding of a molybdenum-hafnium alloy

International Nuclear Information System (INIS)

Lakhtin, Yu.M.; Kogan, Ya.D.; Shashkov, D.P.; Likhacheva, T.E.

1982-01-01

The influence of a preliminary plastic strain on the structure and properties of molybdenum alloy with 0.2 wt.% Hf upon nitriding in the ammonia medium at 900-1200 deg C during 1-6 h is investigated. The study of microhardness distribution across the nitrided layer thickness has shown that with increase of the degree of preliminary plastic strain up to 50 % the nitrided layer hardness decreases and with further reduction growth up to 90 % - increases. Nitriding sharply (hundred times) increases wear resistance of molybdenum alloy with hafnium addition. At the reduction degree 25 % the wear resistance is less than at other values of percentage reduction in area owing to the minimum thickness of the nitride zone. The alloy strained before nitriding by 25 % has shown the best results during heat resistance testing

Titanium by design: TRIP titanium alloy

Science.gov (United States)

Tran, Jamie

Motivated by the prospect of lower cost Ti production processes, new directions in Ti alloy design were explored for naval and automotive applications. Building on the experience of the Steel Research Group at Northwestern University, an analogous design process was taken with titanium. As a new project, essential kinetic databases and models were developed for the design process and used to create a prototype design. Diffusion kinetic models were developed to predict the change in phase compositions and microstructure during heat treatment. Combining a mobility database created in this research with a licensed thermodynamic database, ThermoCalc and DICTRA software was used to model kinetic compositional changes in titanium alloys. Experimental diffusion couples were created and compared to DICTRA simulations to refine mobility parameters in the titanium mobility database. The software and database were able to predict homogenization times and the beta→alpha plate thickening kinetics during cooling in the near-alpha Ti5111 alloy. The results of these models were compared to LEAP microanalysis and found to be in reasonable agreement. Powder metallurgy was explored using SPS at GM R&D to reduce the cost of titanium alloys. Fully dense Ti5111 alloys were produced and achieved similar microstructures to wrought Ti5111. High levels of oxygen in these alloys increased the strength while reducing the ductility. Preliminary Ti5111+Y alloys were created, where yttrium additions successfully gettered excess oxygen to create oxides. However, undesirable large oxides formed, indicating more research is needed into the homogeneous distribution of the yttrium powder to create finer oxides. Principles established in steels were used to optimize the beta phase transformation stability for martensite transformation toughening in titanium alloys. The Olson-Cohen kinetic model is calibrated to shear strains in titanium. A frictional work database is established for common alloying

Nitriding of Ti substrate using energetic ions from plasma focus device

International Nuclear Information System (INIS)

Henriquez, A; Bhuyan, H; Favre, M; Bora, B; Wyndham, E; Chuaqui, H; Mändl, S; Gerlach, J W; Manova, D

2012-01-01

Plasma Focus (PF) discharge is a pulsed plasma producing discharge that generates high temperature and high density plasma for a short duration. PF devices are known to emit intense ion beams pulses of characteristic energy in the keV to a few MeV range, in a time scale of tens of nanoseconds. We have previously investigated the ion flux and energy spectrum of ion beams emitted from a low energy PF, operating at 20 kV, with 1.8 kJ stored energy. It was observed that the ion beams have wide range of energy and intensity spectra with a clear angular anisotropy. Due to the wide range of ion energy and intensity spectra PF has become a subject of current interest for its applications in material sciences including surface modification and thin film deposition. The purpose of this study is the formation of titanium nitride (TiN) thin film and to investigate the structural properties of the TiN thin films in terms of PF angular positions. Substrates like Ti and Ti/Si were nitrided in a 1.8 kJ PF device at different angular positions with respect to the PF axis in order to correlate their surface properties with ion beam parameters. Preliminary characterizations of the ion implanted substrates have been conducted, using SEM, EDX and XRD. Our results indicate the formation of nanocrystalline TiN thin film only in certain angular positions. Angular dependency of the surface morphology was observed, which shows that the surface features strongly depends on ion beam energy and flux. With increasing angular positions, a reduction in the deposition rate and the sputter rate is observed. A pronounced nanostructured surface is only observed at the axis of the pinched plasma column, indicating the dominant role of sputtering and perhaps melting and fast re-crystallization of the surface in creating the nanostructures.

Ab Initio Study of the Atomic Level Structure of the Rutile TiO2(110)-Titanium Nitride (TiN) Interface.

Science.gov (United States)

Gutiérrez Moreno, José Julio; Nolan, Michael

2017-11-01

Titanium nitride (TiN) is widely used in industry as a protective coating due to its hardness and resistance to corrosion and can spontaneously form a thin oxide layer when it is exposed to air, which could modify the properties of the coating. With limited understanding of the TiO 2 -TiN interfacial system at present, this work aims to describe the structural and electronic properties of oxidized TiN based on a density functional theory (DFT) study of the rutile TiO 2 (110)-TiN(100) interface model system, also including Hubbard +U correction on Ti 3d states. The small lattice mismatch gives a good stability to the TiO 2 -TiN interface after depositing the oxide onto TiN through the formation of interfacial Ti-O bonds. Our DFT+U study shows the presence of Ti 3+ cations in the TiO 2 region, which are preferentially located next to the interface region as well as the rotation of the rutile TiO 2 octahedra in the interface structure. The DFT+U TiO 2 electronic density of states (EDOS) shows localized Ti 3+ defect states forming in the midgap between the top edge of the valence and the bottom of the conduction band. We increase the complexity of our models by the introduction of nonstoichiometric compositions. Although the vacancy formation energies for Ti in TiN (E vac (Ti) ≥ 4.03 eV) or O in the oxide (E vac (O) ≥ 3.40 eV) are quite high relative to perfect TiO 2 -TiN, defects are known to form during the oxide growth and can therefore be present after TiO 2 formation. Our results show that a structure with exchanged O and N can lie 0.82 eV higher in energy than the perfect system, suggesting the stability of structures with interdiffused O and N anions at ambient conditions. The presence of N in TiO 2 introduces N 2p states localized between the top edge of the O 2p valence states and the midgap Ti 3+ 3d states, thus reducing the band gap in the TiO 2 region for the exchanged O/N interface EDOS. The outcomes of these simulations give us a most comprehensive

CVD Diamond, DLC, and c-BN Coatings for Solid Film Lubrication

Science.gov (United States)

Miyoshi, Kazuhisa

1998-01-01

When the main criteria for judging coating performance were coefficient of friction and wear rate, which had to be less than 0.1 and 10(exp -6) mm(exp 3)/N-m, respectively, carbon- and nitrogen-ion-implanted, fine-grain CVD diamond and DLC ion beam deposited on fine-grain CVD diamond met the requirements regardless of environment (vacuum, nitrogen, and air).

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

International Nuclear Information System (INIS)

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

1985-03-01

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

Method of production of hollow silicon nitride articles

International Nuclear Information System (INIS)

Parr, N.L.; Brown, R.L.

1971-01-01

The hollow articles prepared according to the invention have a high density, exhibit no internal stresses and correspond to high demands of tolerance and surface quality. One obtains these by flame spraying silicon powder on a pre-heated form designed with separating agent - e.g. NaCl. After removing the form, the silicon is nitridated to silicon nitride by heating in N 2 or in an atmosphere of ammonia. This process can be interrupted if the article is also to be mechanically processed, and then the nitridation can be completed. (Hoe/LH) [de

IMPACT OF VIBRATORY AND ROTATIONAL SHOT PEENING ONTO SELECTED PROPERTIES OF TITANIUM ALLOY SURFACE LAYER

Directory of Open Access Journals (Sweden)

Kazimierz Zaleski

2014-06-01

Full Text Available This study presents the results of tests on impact of vibratory and rotational shot peening of the Ti6A12Mo2Cr titanium alloy onto the processed object surface roughness and surface layer microhardness. The external surfaces of ring-shaped samples were shot peened. The preceding process consisted of turning with a cubic boron nitride blade knife. Steel beads, having a diameter of 6 mm, were used as a processing medium. The variable parameters of shot peening were vibrator amplitude and shot peening time. The range of recommended technological parameters for vibratory and rotational shot peening was determined. As a result of shot peening, the surface roughness could be reduced by approximately 4 times and the surface layer could be hardened to the depth of approximately 0.4 mm.

Layer by layer assembly of catalase and amine-terminated ionic liquid onto titanium nitride nanoparticles modified glassy carbon electrode: Study of direct voltammetry and bioelectrocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Saadati, Shagayegh [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Salimi, Abdollah, E-mail: absalimi@uok.ac.ir [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Hallaj, Rahman; Rostami, Amin [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of)