WorldWideScience

Sample records for nitride nanocrystalline coatings

  1. Toughness enhancement in zirconium-tungsten-nitride nanocrystalline hard coatings

    Science.gov (United States)

    Dubey, P.; Srivastava, S.; Chandra, R.; Ramana, C. V.

    2016-07-01

    An approach is presented to increase the toughness (KIC) while retaining high hardness (H) of Zr-W-N nanocrystalline coatings using energetic ions bombardment. Tuning KIC and H values was made possible by a careful control over the substrate bias, i.e., the kinetic energy (Uk˜9-99 J/cm3) of the bombarding ions, while keeping the deposition temperature relatively low (200 oC). Structural and mechanical characterization revealed a maximum wear resistance (H/Er˜0.23) and fracture toughness (KIC˜2.25 MPa √{ m } ) of ZrWN coatings at Uk˜72 J/cm3. A direct Uk-microstructure-KIC-H relationship suggests that tailoring mechanical properties for a given application is possible by tuning Uk and, hence, ZrWN-coatings' microstructure.

  2. A nanoindentation study of magnetron co-sputtered nanocrystalline ternary nitride coatings

    Directory of Open Access Journals (Sweden)

    Yeung W.Y.

    2006-01-01

    Full Text Available Nanoindentation testing was used to determine the hardness, elastic modulus and plasticity parameter of three newly developed ternary nitride coatings with nano-sized grains. With decreasing nitrogen deposition pressure, grain diameter of the coatings decreases that leads to both higher nanohardness and elastic modulus with conservation of satisfactory values of plasticity characteristic.

  3. Preparation and Instability of Nanocrystalline Cuprous Nitride.

    Science.gov (United States)

    Reichert, Malinda D; White, Miles A; Thompson, Michelle J; Miller, Gordon J; Vela, Javier

    2015-07-06

    Low-dimensional cuprous nitride (Cu3N) was synthesized by nitridation (ammonolysis) of cuprous oxide (Cu2O) nanocrystals using either ammonia (NH3) or urea (H2NCONH2) as the nitrogen source. The resulting nanocrystalline Cu3N spontaneously decomposes to nanocrystalline CuO in the presence of both water and oxygen from air at room temperature. Ammonia was produced in 60% chemical yield during Cu3N decomposition, as measured using the colorimetric indophenol method. Because Cu3N decomposition requires H2O and produces substoichiometric amounts of NH3, we conclude that this reaction proceeds through a complex stoichiometry that involves the concomitant release of both N2 and NH3. This is a thermodynamically unfavorable outcome, strongly indicating that H2O (and thus NH3 production) facilitate the kinetics of the reaction by lowering the energy barrier for Cu3N decomposition. The three different Cu2O, Cu3N, and CuO nanocrystalline phases were characterized by a combination of optical absorption, powder X-ray diffraction, transmission electron microscopy, and electronic density of states obtained from electronic structure calculations on the bulk solids. The relative ease of interconversion between these interesting and inexpensive materials bears possible implications for catalytic and optoelectronic applications.

  4. Preparation of Cubic Boron Nitride Coating on WC-Co Substrate by Micro/Nanocrystalline Diamond Film Interlayer%基于微纳米金刚石过渡层的cBN刀具涂层制备

    Institute of Scientific and Technical Information of China (English)

    徐锋; 左敦稳; 张旭辉; 户海峰; 张骋; 王珉

    2013-01-01

    Cubic Boron Nitride(cBN) is a super-hard material, of which hardness is only less than diamond. But it has excellent chemical stability, especially no chemical reaction with ferrous materials. The cBN coating has irreplaceable function in the application of modern cutting tools. Research is carried out on the preparation of cBN coating on YG6 by micro/nanocrystalline diamond (M/NCD) film inter-layer. The micro/nanocrystalline diamond film is deposited in hot filament chemical vapor deposition system and cBN is deposited in radio frequency magnetron sputtering system. The scanning electron microscopy (SEM), Raman, atomic force microscopy(AFM), Fourier transferred infrared(FTIR) and in-denter are used to investigate the content, morphology and adhesion of the coating. The results show that the adhesion of cBN coating on WC-Co by micro/nanocrystalline diamond interlayer is much higher than that by nano diamond interlayer. The moderate bias voltage is important for the cBN film deposition in the magnetron sputtering process.%立方氮化硼(Cubic Boron Nitride,cBN)是仅次于金刚石的超硬材料,比金刚石具有更高的化学稳定性,可以胜任铁系金属的加工.本文在YG6硬质合金上基于微纳米金刚石过渡层开展cBN涂层的制备研究.本文在热丝化学气相沉积系统中制备微纳米金刚石过渡层(Micro/nanocrystalline diamond,M/NCD),在射频磁控溅射系统中制备cBN涂层,并对M/NCD与cBN涂层进行了成分、微观形貌与结合性能的研究.研究结果发现,在硬质合金基体上,M/NCD过渡层的结合性能明显优于NCD过渡层.磁控溅射制备cBN涂层过程中,存在适合cBN沉积的衬底偏压阈值,过高或过低的衬底偏压均不利于cBN含量的提高.

  5. 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...

  6. Transparent nanocrystalline diamond coatings and devices

    Energy Technology Data Exchange (ETDEWEB)

    Sumant, Anirudha V.; Khan, Adam

    2017-08-22

    A method for coating a substrate comprises producing a plasma ball using a microwave plasma source in the presence of a mixture of gases. The plasma ball has a diameter. The plasma ball is disposed at a first distance from the substrate and the substrate is maintained at a first temperature. The plasma ball is maintained at the first distance from the substrate, and a diamond coating is deposited on the substrate. The diamond coating has a thickness. Furthermore, the diamond coating has an optical transparency of greater than about 80%. The diamond coating can include nanocrystalline diamond. The microwave plasma source can have a frequency of about 915 MHz.

  7. Nanocrystalline Ni-W coatings on copper

    Energy Technology Data Exchange (ETDEWEB)

    Panagopoulos, C.N., E-mail: chpanag@metal.ntua.gr [Laboratory of Physical Metallurgy, National Technical University of Athens, Zografos, 15780, Athens (Greece); Plainakis, G.D.; Lagaris, D.A. [Laboratory of Physical Metallurgy, National Technical University of Athens, Zografos, 15780, Athens (Greece)

    2011-04-15

    Nanocrystalline Ni-W coatings were produced on copper substrates with the aid of electrodeposition technique. The morphology, chemical composition and structure of the produced coatings were examined with the aid of scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS) and X-ray diffraction (XRD) techniques. The microhardness of alloy Ni-W coatings on copper substrate was also studied. The adhesion between the Ni-W coating, having W content 50 wt%, and the copper substrate, was also studied with a scratch testing apparatus. The scratch tests resulted in the coatings suffering an intensive brittle fracture and minor delamination.

  8. A New Method for Preparation of Nanocrystalline Molybdenum Nitride

    Institute of Scientific and Technical Information of China (English)

    SHEN Long-Hai; CUI Qi-Liang; ZHANG Jian; LI Xue-Fei; ZHOU Qiang; ZOU Guang-Tian

    2005-01-01

    @@ Nanocrystalline molybdenum nitride (γ-Mo2N) with the cubic structure is prepared by the direct-current arc discharge method in N2 gas, using metal Mo or W rod as a cathode. The x-ray diffraction (XRD) and transmission electron microscopy (TEM) are used to characterize the product. It is found that the conversion of Mo to γ-Mo2N and affinity of Mo to N2 are determined by the nitrogen pressur e. Moreover, we compare the effect of Mo and W rod as a cathode for preparing γ-Mo2N. The average size of γ-Mo2N particles is about 5nm. The rapid quenching mechanism can be used to explain the formation of nanocrystalline γ-Mo2N.

  9. Low temperature solid-state synthesis of nanocrystalline gallium nitride

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Liangbiao, E-mail: wlb6641@163.com [Hefei National Laboratory for Physical Science at Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China); Shi, Liang; Li, Qianwen; Si, Lulu; Zhu, Yongchun; Qian, Yitai [Hefei National Laboratory for Physical Science at Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2012-11-15

    Graphical abstract: Display Omitted Highlights: ► GaN nanocrystalline was prepared via a solid-state reacion at relatively low temperature. ► The sizes and crystallinities of the GaN samples obtained at the different temperatures are investigated. ► The GaN sample has oxidation resistance and good thermal stability below 1000 °C. -- Abstract: Nanocrystalline gallium nitride was synthesized by a solid-state reaction of metallic magnesium powder, gallium sesquioxide and sodium amide in a stainless steel autoclave at a relatively low temperature (400–550 °C). The structures and morphologies of the obtained products were derived from X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). XRD patterns indicated that the products were hexagonal GaN (JCPDS card no. 76-0703). The influence of reaction temperature on size of the products was studied by XRD and TEM. Furthermore, the thermal stability and oxidation resistance of the nanocrystalline GaN were also investigated. It had good thermal stability and oxidation resistance below 800 °C in air.

  10. Microstructure and Performances of Nanocrystalline Zinc-nickel Alloy Coatings

    Institute of Scientific and Technical Information of China (English)

    LI Guang-yu; LIAN Jian-she; NIU Li-yuan; JIANG Zhong-hao

    2004-01-01

    Nanocrystalline zinc-nickel alloy coatings were deposited from an alkaline zincate bath contained an organic additive that can reduce polarization and a complexing agent. SEM and TEM observations and XRD analysis were performed to examine the microstructure and phase composition of the coatings. The nickel content in deposits is 12.0~14.7% and the coating is consisted of single nanocrystalline γ-phase structure (Ni5Zn21), with grain average grain size about 15nm. The nanocrystalline zinc-nickel alloy coatings have better corrosion resistance, less brittleness and higher microhardness than the conventional zinc coatings.

  11. Studies on nanocrystalline zinc coating

    Indian Academy of Sciences (India)

    H B Muralidhara; Y Arthoba Naik

    2008-08-01

    Nano zinc coatings were deposited on mild steel by electrodeposition. The effect of additive on the morphology of crystal size on zinc deposit surface and corrosion properties were investigated. Corrosion tests were performed for dull zinc deposits and bright zinc deposits in aqueous NaCl solution (3.5 wt.%) using electrochemical measurements. The results showed that addition of additive in the deposition process of zinc significantly increased the corrosion resistance. The surface morphology of the zinc deposits was studied by scanning electron microscopy (SEM). The preferred orientation and average size of the zinc electrodeposited particles were obtained by X-ray diffraction analysis. The particles size was also characterized by TEM analysis.

  12. Microstructure and Performances of Nanocrystalline Zinc-nickel Alloy Coatings

    Institute of Scientific and Technical Information of China (English)

    LIGuang-yu; LIANJian-she; NIULi-yuan; JIANGZhong-hao

    2004-01-01

    Nanocrystalline zinc-nickel alloy coatings were deposited from an alkaline zincate bath contained an organic additive that can reduce polarization and a complexing agent. SEM and TEM observations and XRD analysis were performed to examine the microstructure and phase composition of the coatings. The nickel content in deposits is 12.0-14.7% and the coating is consisted of single nanectystalline γ-phase structure (Ni5Zn21), with grain average grain size about 15nm. The nanocrystalline zinc-nickel alloy coatings have better corrosion resistance, less brittleness and higher microhardness than the conventional zinc coatings.

  13. Nanocrystalline hydroxyapatite/titania coatings on titanium improves osteoblast adhesion.

    Science.gov (United States)

    Sato, Michiko; Aslani, Arash; Sambito, Marisa A; Kalkhoran, Nader M; Slamovich, Elliott B; Webster, Thomas J

    2008-01-01

    Bulk hydroxyapatite (HA) and titania have been used to improve the osseointegration of orthopedic implants. For this reason, composites of HA and titania have been receiving increased attention in orthopedics as novel coating materials. The objective of this in vitro study was to produce nanophase (i.e., materials with grain size less than 100 nm) HA/titania coatings on titanium. The adhesion of bone forming cells (osteoblasts) on the composite coatings were also assessed and compared with single-phase nanotitania and nano-HA titanium coatings. Nanocrystalline HA powders were synthesized through wet chemistry and hydrothermal treatments at 200 degrees C. Nanocrystalline titania powders obtained commercially were mixed with the nanocrystalline HA powders at various weight ratios. The mixed powders were then deposited on titanium utilizing a room-temperature coating process called IonTite. The results of the present study showed that such coatings maintained the chemistry and crystallite size of the original HA and titania powders. Moreover, osteoblasts adherent on single-phase nanotitania coatings were well-spread whereas they became more round and extended distinct filopodia on the composite and single-phase HA coatings. Interestingly, the number of osteoblasts adherent on the nanotitania/HA composite coatings at weight ratios of 2/1 and 1/2 were significantly greater compared with single-phase nanotitania coatings, currently-used plasma-sprayed HA coatings, and uncoated titanium. These findings suggest that nanotitania/HA coatings on titanium should be further studied for improved orthopedic applications.

  14. Silicon Nitride Antireflection Coatings for Photovoltaic Cells

    Science.gov (United States)

    Johnson, C.; Wydeven, T.; Donohoe, K.

    1984-01-01

    Chemical-vapor deposition adapted to yield graded index of refraction. Silicon nitride deposited in layers, refractive index of which decreases with distance away from cell/coating interface. Changing index of refraction allows adjustment of spectral transmittance for wavelengths which cell is most effective at converting light to electric current. Average conversion efficiency of solar cells increased from 8.84 percent to 12.63 percent.

  15. Performance of chromium nitride based coatings under plastic processing conditions

    OpenAIRE

    Cunha, l.; Andritschky, M.; Pischow, K.; Wang, Z.(Institute of High Energy Physics, Beijing, China); Zarychta, A.; Miranda, A. S.; A.M. Cunha

    2000-01-01

    Chromium nitride based coatings were produced in the form of monolithic and multilayer coatings, by DC and RF reactive magnetron sputtering. These coatings were deposited onto stainless steel and tool steel substrates. Chromium nitride coatings have;proved to be wear and corrosion resistant. The combination of these characteristics was necessary to protect surfaces during plastic processing. In order to select the best coatings, some mechanical and tribological tests were performed. Har...

  16. 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.

  17. Nitridation of nanocrystalline TiO{sub 2} thin films by treatment with ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Romero-Gomez, P.; Rico, V.; Espinos, J.P.; Gonzalez-Elipe, Agustin R. [Instituto de Ciencia de Materiales de Sevilla (CSIC-Univ. Sevilla), Avda. Americo Vespucio 49, 41092 Sevilla (Spain); Palgrave, Robert G. [Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA (United Kingdom); Egdell, Russell G., E-mail: russell.egdell@chem.ox.ac.u [Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA (United Kingdom)

    2011-03-31

    Nanocrystalline anatase (TiO{sub 2}) thin films prepared by a physical vapour deposition method were nitrided by annealing in flowing NH{sub 3} at temperatures ranging between 650 {sup o}C and 700 {sup o}C. It was established that there was a narrow window of temperatures which allowed both incorporation of interstitial nitrogen into the films with retention of the anatase phase without chemical reduction and preservation of the characteristic nanocrystalline morphology. These optimally modified films responded to visible light in photowetting tests and showed the ability to degrade an organic dye under visible light irradiation.

  18. CEMS of nitride coatings in agressive environments

    Energy Technology Data Exchange (ETDEWEB)

    Hanzel, D. [University of Ljubljana, J. Stefan Institute (Slovenia); Agudelo, A.C.; Gancedo, J.R. [Instituto de Quimica-Fisica ' Rocasolano' , CSIC (Spain); Lakatos-Varsanyi, M. [Eoetvoes University, Department of Physical Chemistry (Hungary); Marco, J.F. [Instituto de Quimica-Fisica ' Rocasolano' , CSIC (Spain)

    1998-12-15

    The corrosion properties of single layered TiN and CrN films have been compared to bi-layered and multi-layered Ti/TiN films. XPS has showed that in humid SO{sub 2} atmosphere the best corrosion properties have been achieved by a multi-layered Ti/TiN coating. Cyclic voltammetry in acetate buffer has been applied to measure the porousity and corrosion resistance of coatings. The best results have been achieved by multi-layered Ti/TiN and CrN films. Conversion electron Moessbauer spectroscopy has been used to study the changes in the interface Fe/TiN during thermal treatment in UHV. It has been shown that the amount of iron nitrides in the interface increases with increasing temperature.

  19. Improved corrosion resistance of 316L stainless steel by nanocrystalline and electrochemical nitridation in artificial saliva solution

    Science.gov (United States)

    Lv, Jinlong; Liang, Tongxiang

    2015-12-01

    The fluoride ion in artificial saliva significantly changed semiconductor characteristic of the passive film formed on the surface of 316L stainless steels. The electrochemical results showed that nanocrystalline α‧-martensite improved corrosion resistance of the stainless steel in a typical artificial saliva compared with coarse grained stainless steel. Moreover, comparing with nitrided coarse grained stainless steel, corrosion resistance of the nitrided nanocrystalline stainless steel was also improved significantly, even in artificial saliva solution containing fluoride ion. The present study showed that the cryogenic cold rolling and electrochemical nitridation improved corrosion resistance of 316L stainless steel for the dental application.

  20. Structure of the local environment of titanium atoms in multicomponent nitride coatings produced by plasma-ion techniques

    Science.gov (United States)

    Krysina, O. V.; Timchenko, N. A.; Koval, N. N.; Zubavichus, Ya V.

    2016-01-01

    An experiment was performed to examine the X-ray Absorption Near-Edge Structure (XANES) and the Extended X-ray Absorption Fine Structure (EXAFS) near the K-edge of titanium in nanocrystalline titanium nitride coatings containing additives of copper, silicon, and aluminum. Using the observation data, the structure parameters of the local environment of titanium atoms have been estimated for the coatings. According to crystallographic data, the Ti-N distance in the bulk phase of titanium nitride is 2.12 Å and the Ti-Ti distance is 3.0 Å. Nearly these values have been obtained for the respective parameters of the coatings. The presence of copper as an additive in a TiN coating increases the Ti-N distance inappreciably compared to that estimated for titanium nitride, whereas addition of silicon decreases the bond distance. It has been revealed that the copper and silicon atoms in Ti-Cu-N and Ti-Si-N coatings do not enter into the crystallographic phase of titanium nitride and do not form bonds with titanium and nitrogen, whereas the aluminum atoms in Ti-Al-N coatings form intermetallic phases with titanium and nitride phases.

  1. Superhard Nanocrystalline Homometallic Stainless Steel on Steel for Seamless Coatings

    Science.gov (United States)

    Tobin, Eric J.; Hafley, R. (Technical Monitor)

    2002-01-01

    The objective of this work is to deposit nanocrystalline stainless steel onto steel substrates (homometallic) for enhanced wear and corrosion resistance. Homometallic coatings provide superior adhesion, and it has been shown that ultrafine-grained materials exhibit the increased hardness and decreased permeability desired for protective coatings. Nanocrystals will be produced by controlling nucleation and growth and use of an ion beam during deposition by e-beam evaporation or sputtering. Phase I is depositing 31 6L nanocrystalline stainless steel onto 31 6L stainless steel substrates. These coatings exhibit hardnesses comparable to those normally obtained for ceramic coatings such ZrO2, and possess the superior adhesion of seamless, homometallic coatings. Hardening the surface with a similar material also enhances adhesion, by avoiding problems associated with thermal and lattice mismatch. So far we have deposited nanocrystalline homometallic 316L stainless steel coatings by varying the ions and the current density of the ion beams. For all deposition conditions we have produced smooth, uniform, superhard coatings. All coatings exhibit hardness of at least 200% harder than that of bulk materials. Our measurements indicate that there is a direct relationship between nanohardness and the current density of the ion beam. Stress measurements indicate that stress in the films is increasingly proportional to current density of the ion beam. TEM, XPS, and XRD results indicate that the coated layers consist of FCC structure nanocrystallites with a dimension of about 10 to 20 nm. The Ni and Mo concentration of these coating are lower than those of bulk 316L but the concentration of Cr is higher.

  2. Reactive Mechanical Alloying Synthesis of Nanocrystalline Cubic Zirconium Nitride

    Institute of Scientific and Technical Information of China (English)

    QIU Li-Xia; YAO Bin; DING Zhan-Hui; ZHAO Xu-Dong; JI Hong; DU Xiao-Bo; JIA Xiao-Peng; ZHENG Wei-Tao

    2008-01-01

    Zirconium nitride powders with rock salt structure (γ-ZrNx) are prepared by mechanical milling of a mixture of Zirconium and hexagonal boron nitride (h-BN) powders.The products are analysed by x-ray diffraction (XRD),scanning electron microscopy (SEM),and Raman spectroscopy (RS).The formation mechanism of γ-ZrNx by ball milling technique is investigated in detail.N atoms diffuse from amorphous BN (a-BN) into Zr to form Zr(N) solid solution alloy,then the Zr(N) solid solution alloy decomposes into γ-ZrNx.No ZrB2 is observed in the as-milled samples or the samples annealed at 1050℃ for 2 h.

  3. Low temperature synthesis of nanocrystalline titanium nitride from a single-source precursor of titanium and nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Wu Meining, E-mail: wmn-wz@163.co [Oujiang College, Wenzhou University, Wenzhou, Zhejiang 325027 (China)

    2009-11-03

    Nanocrystalline titanium nitride has been prepared via a convenient route from a single-source precursor of titanium and nitrogen (ammonium fluotitanate) in an autoclave at 650 deg. C. X-ray powder diffraction patterns indicate that the product is cubic titanium nitride, and the cell constant is a = 4.235 A. Transmission electron microscopy image shows that it consists of particles with an average size of about 40 nm in diameter. The product was also studied by BET and TGA.

  4. Electrodeposition of Nanocrystalline Cobalt Phosphorous Coatings as a Hard Chrome Alternative

    Science.gov (United States)

    2014-11-01

    1 ASETSDefense 2014 Electrodeposition of Nanocrystalline Cobalt Phosphorous Coatings as a Hard Chrome Alternative Ruben A. Prado, CEF...COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Electrodeposition of Nanocrystalline Cobalt Phosphorous Coatings as a Hard Chrome Alternative...Mil-Spec development 3 ASETSDefense 2014 ■ Demonstrate/Validate pulsed electrodeposition of Nanocrystalline Cobalt -Phosphorous (nCoP) alloy

  5. Oxidation resistant nanocrystalline MCrAl(Y) coatings and methods of forming such coatings

    Science.gov (United States)

    Cheruvu, Narayana S.; Wei, Ronghua

    2014-07-29

    The present disclosure relates to an oxidation resistant nanocrystalline coating and a method of forming an oxidation resistant nanocrystalline coating. An oxidation resistant coating comprising an MCrAl(Y) alloy may be deposited on a substrate, wherein M, includes iron, nickel, cobalt, or combinations thereof present greater than 50 wt % of the MCrAl(Y) alloy, chromium is present in the range of 15 wt % to 30 wt % of the MCrAl(Y) alloy, aluminum is present in the range of 6 wt % to 12 wt % of the MCrAl(Y) alloy and yttrium, is optionally present in the range of 0.1 wt % to 0.5 wt % of the MCrAl(Y) alloy. In addition, the coating may exhibit a grain size of 200 nm or less as deposited.

  6. Biological evaluation of ultrananocrystalline and nanocrystalline diamond coatings.

    Science.gov (United States)

    Skoog, Shelby A; Kumar, Girish; Zheng, Jiwen; Sumant, Anirudha V; Goering, Peter L; Narayan, Roger J

    2016-12-01

    Nanostructured biomaterials have been investigated for achieving desirable tissue-material interactions in medical implants. Ultrananocrystalline diamond (UNCD) and nanocrystalline diamond (NCD) coatings are the two most studied classes of synthetic diamond coatings; these materials are grown using chemical vapor deposition and are classified based on their nanostructure, grain size, and sp(3) content. UNCD and NCD are mechanically robust, chemically inert, biocompatible, and wear resistant, making them ideal implant coatings. UNCD and NCD have been recently investigated for ophthalmic, cardiovascular, dental, and orthopaedic device applications. The aim of this study was (a) to evaluate the in vitro biocompatibility of UNCD and NCD coatings and (b) to determine if variations in surface topography and sp(3) content affect cellular response. Diamond coatings with various nanoscale topographies (grain sizes 5-400 nm) were deposited on silicon substrates using microwave plasma chemical vapor deposition. Scanning electron microscopy and atomic force microscopy revealed uniform coatings with different scales of surface topography; Raman spectroscopy confirmed the presence of carbon bonding typical of diamond coatings. Cell viability, proliferation, and morphology responses of human bone marrow-derived mesenchymal stem cells (hBMSCs) to UNCD and NCD surfaces were evaluated. The hBMSCs on UNCD and NCD coatings exhibited similar cell viability, proliferation, and morphology as those on the control material, tissue culture polystyrene. No significant differences in cellular response were observed on UNCD and NCD coatings with different nanoscale topographies. Our data shows that both UNCD and NCD coatings demonstrate in vitro biocompatibility irrespective of surface topography.

  7. A multilayer innovative solution to improve the adhesion of nanocrystalline diamond coatings

    Energy Technology Data Exchange (ETDEWEB)

    Poulon-Quintin, A., E-mail: poulon@icmcb-bordeaux.cnrs.fr [CNRS, ICMCB, UPR 9048, F-33600 Pessac (France); Univ. Bordeaux, ICMCB, UPR 9048, F-33600 Pessac (France); Faure, C.; Teulé-Gay, L.; Manaud, J.P. [CNRS, ICMCB, UPR 9048, F-33600 Pessac (France); Univ. Bordeaux, ICMCB, UPR 9048, F-33600 Pessac (France)

    2015-03-15

    Highlights: • Improvement of the NCD adhesion on WC-12%Co substrates for tooling applications using a multi-interlayer additional system. • Reduction of the graphite layer thickness and continuity at the interface with the diamond. • Transmission electron microscopy study for a better understanding of the diffusion phenomena occurring at the interfaces. - Abstract: Nano-crystalline diamond (NCD) films grown under negative biased substrates by chemical vapor deposition (CVD) are widely used as surface overlay coating onto cermet WC-Co cutting tools to get better performances. To improve the diamond adhesion to the cermet substrate, suitable multi-layer systems have been added. They are composed of a cobalt diffusion barrier close to the substrate (single and sequenced nitrides layers) coated with a nucleation extra layer to improve the nucleus density of diamond during CVD processing. For all systems, before and after diamond deposition, transmission electron microscopy (TEM) has been performed for a better understanding of the diffusion phenomena occurring at the interfaces and to evaluate the presence of graphitic species at the interface with the diamond. Innovative multilayer system dedicated to the regulation of cobalt diffusion coated with a bilayer system optimized for the carbon diffusion control, is shown as an efficient solution to significantly reduce the graphite layer formation at the interface with the diamond down to 10 nm thick and to increase the adhesion of NCD diamond layer as scratch-tests confirm.

  8. The High performance of nanocrystalline CVD diamond coated hip joints in wear simulator test.

    Science.gov (United States)

    Maru, M M; Amaral, M; Rodrigues, S P; Santos, R; Gouvea, C P; Archanjo, B S; Trommer, R M; Oliveira, F J; Silva, R F; Achete, C A

    2015-09-01

    The superior biotribological performance of nanocrystalline diamond (NCD) coatings grown by a chemical vapor deposition (CVD) method was already shown to demonstrate high wear resistance in ball on plate experiments under physiological liquid lubrication. However, tests with a close-to-real approach were missing and this constitutes the aim of the present work. Hip joint wear simulator tests were performed with cups and heads made of silicon nitride coated with NCD of ~10 μm in thickness. Five million testing cycles (Mc) were run, which represent nearly five years of hip joint implant activity in a patient. For the wear analysis, gravimetry, profilometry, scanning electron microscopy and Raman spectroscopy techniques were used. After 0.5 Mc of wear test, truncation of the protruded regions of the NCD film happened as a result of a fine-scale abrasive wear mechanism, evolving to extensive plateau regions and highly polished surface condition (Ra<10nm). Such surface modification took place without any catastrophic features as cracking, grain pullouts or delamination of the coatings. A steady state volumetric wear rate of 0.02 mm(3)/Mc, equivalent to a linear wear of 0.27 μm/Mc favorably compares with the best performance reported in the literature for the fourth generation alumina ceramic (0.05 mm(3)/Mc). Also, squeaking, quite common phenomenon in hard-on-hard systems, was absent in the present all-NCD system.

  9. Wear monitoring of protective nitride coatings using image processing

    DEFF Research Database (Denmark)

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

    2010-01-01

    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...... processing by color detection is a potential technique for early 25 warning or determination of residual thickness of tribological tool coatings prior to complete wear....

  10. Hard and low friction nitride coatings and methods for forming the same

    Science.gov (United States)

    Erdemir, Ali; Urgen, Mustafa; Cakir, Ali Fuat; Eryilmaz, Osman Levent; Kazmanli, Kursat; Keles, Ozgul

    2007-05-01

    An improved coating material possessing super-hard and low friction properties and a method for forming the same. The improved coating material includes the use of a noble metal or soft metal homogeneously distributed within a hard nitride material. The addition of small amounts of such metals into nitrides such as molybdenum nitride, titanium nitride, and chromium nitride results in as much as increasing of the hardness of the material as well as decreasing the friction coefficient and increasing the oxidation resistance.

  11. Influence of low-temperature nitridation on low-frequency magnetization of Fe82Nb7B10Cu1 nanocrystalline alloy ribbons

    Institute of Scientific and Technical Information of China (English)

    XU Feng; WU Xiao-ling; LI Shan-dong; PENG Kun; CHEN Guang; DU You-wei

    2006-01-01

    The nanocrystalline Fe82Nb7B10Cu1 soft magnetic ribbons were treated with the mixture gas flow of ammonia and hydrogen at 673 K. The influence of the nitridation treatment was studied by the low-frequency permeability spectra. The result shows that this kind of nitridation treatment can improve the soft magnetic properties under some application conditions. The reason for the improvement of the soft magnetic properties by slight nitridation was discussed on the basis of domain wall bulging model. Therefore for the Fe-based nanocrystalline soft magnetic alloy ribbons, the nitridation treatment can be used as an effective and easy method to control the magnetic properties.

  12. Effect of plasma nitriding and titanium nitride coating on the corrosion resistance of titanium.

    Science.gov (United States)

    Wang, Xianli; Bai, Shizhu; Li, Fang; Li, Dongmei; Zhang, Jing; Tian, Min; Zhang, Qian; Tong, Yu; Zhang, Zichuan; Wang, Guowei; Guo, Tianwen; Ma, Chufan

    2016-09-01

    The passive film on the surface of titanium can be destroyed by immersion in a fluoridated acidic medium. Coating with titanium nitride (TiN) may improve the corrosion resistance of titanium. The purpose of this in vitro study was to investigate the effect of duplex treatment with plasma nitriding and TiN coating on the corrosion resistance of cast titanium. Cast titanium was treated with plasma nitriding and TiN coating. The corrosion resistance of the duplex-treated titanium in fluoride-containing artificial saliva was then investigated through electrochemical and immersion tests. The corroded surface was characterized by scanning electron microscopy (SEM) with energy-dispersive spectroscopy surface scan analysis. The data were analyzed using ANOVA (α=.05) RESULTS: Duplex treatment generated a dense and uniform TiN film with a thickness of 4.5 μm. Compared with untreated titanium, the duplex-treated titanium displayed higher corrosion potential (Ecorr) values (Pplasma nitriding and TiN coating significantly improved the corrosion resistance of cast titanium in a fluoride-containing environment. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  13. Tailoring nanocrystalline diamond coated on titanium for osteoblast adhesion.

    Science.gov (United States)

    Pareta, Rajesh; Yang, Lei; Kothari, Abhishek; Sirinrath, Sirivisoot; Xiao, Xingcheng; Sheldon, Brian W; Webster, Thomas J

    2010-10-01

    Diamond coatings with superior chemical stability, antiwear, and cytocompatibility properties have been considered for lengthening the lifetime of metallic orthopedic implants for over a decade. In this study, an attempt to tailor the surface properties of diamond films on titanium to promote osteoblast (bone forming cell) adhesion was reported. The surface properties investigated here included the size of diamond surface features, topography, wettability, and surface chemistry, all of which were controlled during microwave plasma enhanced chemical-vapor-deposition (MPCVD) processes using CH4-Ar-H2 gas mixtures. The hardness and elastic modulus of the diamond films were also determined. H2 concentration in the plasma was altered to control the crystallinity, grain size, and topography of the diamond coatings, and specific plasma gases (O2 and NH3) were introduced to change the surface chemistry of the diamond coatings. To understand the impact of the altered surface properties on osteoblast responses, cell adhesion tests were performed on the various diamond-coated titanium. The results revealed that nanocrystalline diamond (grain sizes applications.

  14. Tribology of nitrided-coated steel-a review

    Directory of Open Access Journals (Sweden)

    Bhaskar Santosh V.

    2017-01-01

    Full Text Available Surface engineering such as surface treatment, coating, and surface modification are employed to increase surface hardness, minimize adhesion, and hence, to reduce friction and improve resistance to wear. To have optimal tribological performance of Physical Vapor Deposition (PVD hard coating to the substrate materials, pretreatment of the substrate materials is always advisable to avoid plastic deformation of the substrate, which may result in eventual coating failure. The surface treatment results in hardening of the substrate and increase in load support effect. Many approaches aim to improve the adhesion of the coatings onto the substrate and nitriding is the one of the best suitable options for the same. In addition to tribological properties, nitriding leads to improved corrosion resistance. Often corrosion resistance is better than that obtainable with other surface engineering processes such as hard-chrome and nickel plating. Ability of this layer to withstand thermal stresses gives stability which extends the surface life of tools and other components exposed to heat. Most importantly, the nitrogen picked-up by the diffusion layer increases the rotating-bending fatigue strength in components. The present article reviews mainly the tribological advancement of different nitrided-coated steels based on the types of coatings, structure, and the tribo-testing parameters, in recent years.

  15. Turbostratic boron nitride coated on high-surface area metal oxide templates

    DEFF Research Database (Denmark)

    Klitgaard, Søren Kegnæs; Egeblad, Kresten; Brorson, M.

    2007-01-01

    Boron nitride coatings on high-surface area MgAl2O4 and Al2O3 have been synthesized and characterized by transmission electron microscopy and by X-ray powder diffraction. The metal oxide templates were coated with boron nitride using a simple nitridation in a flow of ammonia starting from ammonium...

  16. Biomimetic helical rosette nanotubes and nanocrystalline hydroxyapatite coatings on titanium for improving orthopedic implants.

    Science.gov (United States)

    Zhang, Lijie; Chen, Yupeng; Rodriguez, Jose; Fenniri, Hicham; Webster, Thomas J

    2008-01-01

    Natural bone consists of hard nanostructured hydroxyapatite (HA) in a nanostructured protein-based soft hydrogel template (ie, mostly collagen). For this reason, nanostructured HA has been an intriguing coating material on traditionally used titanium for improving orthopedic applications. In addition, helical rosette nanotubes (HRNs), newly developed materials which form through the self-assembly process of DNA base pair building blocks in body solutions, are soft nanotubes with a helical architecture that mimics natural collagen. Thus, the objective of this in vitro study was for the first time to combine the promising attributes of HRNs and nanocrystalline HA on titanium and assess osteoblast (bone-forming cell) functions. Different sizes of nanocrystalline HA were synthesized in this study through a wet chemical precipitation process following either hydrothermal treatment or sintering. Transmission electron microscopy images showed that HRNs aligned with nanocrystalline HA, which indicates a high affinity between both components. Some of the nanocrystalline HA formed dense coatings with HRNs on titanium. More importantly, results demonstrated enhanced osteoblast adhesion on the HRN/nanocrystalline HA-coated titanium compared with conventional uncoated titanium. Among all the HRN/nanocrystalline HA coatings tested, osteoblast adhesion was the greatest when HA nanometer particle size was the smallest. In this manner, this study demonstrated for the first time that biomimetic HRN/nanocrystalline HA coatings on titanium were cytocompatible for osteoblasts and, thus, should be further studied for improving orthopedic implants.

  17. Field emission from Si tips coated with nanocrystalline diamond films

    Institute of Scientific and Technical Information of China (English)

    WANG Wanlu; LIAO Kejun; LIU Gaobin; MA Yong

    2003-01-01

    The electron field emission from Si tips coated with nanocrystalline diamond films was investigated. The Si tips were formed by plasma etching, and nano-diamond films were deposited on the Si tips by hot filament chemical vapor deposition. The radius of curvature for the Si tips was averagely about 50 nm. The microstructure of the diamond films was examined by scanning electron microscopy and Raman spectroscopy. The field emission properties of the samples were measured in an ionpumped vacuum chamber at a pressure of 10-6 Pa. The experimental results showed that the nanostructured films on Si tips exhibited a lower value of the turn-on electric field than those on flat Si substrates. It was found that the tip shape and nondiamond phase in the films had a significant effect on the field emission properties of the films.

  18. Nanocrystalline [beta]-Ta Coating Enhances the Longevity and Bioactivity of Medical Titanium Alloys

    National Research Council Canada - National Science Library

    Linlin Liu; Jiang Xu; Shuyun Jiang

    2016-01-01

      A [beta]-Ta nanocrystalline coating was engineered onto a Ti-6Al-4V substrate using a double cathode glow discharge technique to improve the corrosion resistance and bioactivity of this biomedical alloy...

  19. Cavitation Resistance of TiN Nanocrystalline Coatings with Various Thickness

    National Research Council Canada - National Science Library

    Krella, A

    2009-01-01

    TiN nanocrystalline coatings of various thicknesses deposited on austenitic stainless steel, X6CrNiTi18-10, by means of the cathodic arc evaporation method were investigated in a cavitation tunnel with a slot cavitator...

  20. Nanocrystalline Diamond as a Coating for Joint Implants: Cytotoxicity and Biocompatibility Assessment

    National Research Council Canada - National Science Library

    Amaral, Margarida; Gomes, Pedro S; Lopes, Maria A; Santos, José D; Silva, Rui F; Fernandes, Maria H

    2008-01-01

    Nanocrystalline diamond (NCD) coatings combine a very low surface roughness with the outstanding diamond properties, such as superlative hardness, low self-friction coefficient, high wear and corrosion resistance...

  1. Enhanced optoelectronic performances of vertically aligned hexagonal boron nitride nanowalls-nanocrystalline diamond heterostructures

    Science.gov (United States)

    Sankaran, Kamatchi Jothiramalingam; Hoang, Duc Quang; Kunuku, Srinivasu; Korneychuk, Svetlana; Turner, Stuart; Pobedinskas, Paulius; Drijkoningen, Sien; van Bael, Marlies K.; D' Haen, Jan; Verbeeck, Johan; Leou, Keh-Chyang; Lin, I.-Nan; Haenen, Ken

    2016-07-01

    Field electron emission (FEE) properties of vertically aligned hexagonal boron nitride nanowalls (hBNNWs) grown on Si have been markedly enhanced through the use of nitrogen doped nanocrystalline diamond (nNCD) films as an interlayer. The FEE properties of hBNNWs-nNCD heterostructures show a low turn-on field of 15.2 V/μm, a high FEE current density of 1.48 mA/cm2 and life-time up to a period of 248 min. These values are far superior to those for hBNNWs grown on Si substrates without the nNCD interlayer, which have a turn-on field of 46.6 V/μm with 0.21 mA/cm2 FEE current density and life-time of 27 min. Cross-sectional TEM investigation reveals that the utilization of the diamond interlayer circumvented the formation of amorphous boron nitride prior to the growth of hexagonal boron nitride. Moreover, incorporation of carbon in hBNNWs improves the conductivity of hBNNWs. Such a unique combination of materials results in efficient electron transport crossing nNCD-to-hBNNWs interface and inside the hBNNWs that results in enhanced field emission of electrons. The prospective application of these materials is manifested by plasma illumination measurements with lower threshold voltage (370 V) and longer life-time, authorizing the role of hBNNWs-nNCD heterostructures in the enhancement of electron emission.

  2. Enhanced optoelectronic performances of vertically aligned hexagonal boron nitride nanowalls-nanocrystalline diamond heterostructures.

    Science.gov (United States)

    Sankaran, Kamatchi Jothiramalingam; Hoang, Duc Quang; Kunuku, Srinivasu; Korneychuk, Svetlana; Turner, Stuart; Pobedinskas, Paulius; Drijkoningen, Sien; Van Bael, Marlies K; D' Haen, Jan; Verbeeck, Johan; Leou, Keh-Chyang; Lin, I-Nan; Haenen, Ken

    2016-07-11

    Field electron emission (FEE) properties of vertically aligned hexagonal boron nitride nanowalls (hBNNWs) grown on Si have been markedly enhanced through the use of nitrogen doped nanocrystalline diamond (nNCD) films as an interlayer. The FEE properties of hBNNWs-nNCD heterostructures show a low turn-on field of 15.2 V/μm, a high FEE current density of 1.48 mA/cm(2) and life-time up to a period of 248 min. These values are far superior to those for hBNNWs grown on Si substrates without the nNCD interlayer, which have a turn-on field of 46.6 V/μm with 0.21 mA/cm(2) FEE current density and life-time of 27 min. Cross-sectional TEM investigation reveals that the utilization of the diamond interlayer circumvented the formation of amorphous boron nitride prior to the growth of hexagonal boron nitride. Moreover, incorporation of carbon in hBNNWs improves the conductivity of hBNNWs. Such a unique combination of materials results in efficient electron transport crossing nNCD-to-hBNNWs interface and inside the hBNNWs that results in enhanced field emission of electrons. The prospective application of these materials is manifested by plasma illumination measurements with lower threshold voltage (370 V) and longer life-time, authorizing the role of hBNNWs-nNCD heterostructures in the enhancement of electron emission.

  3. 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.

  4. Reactive Ball Milling to Fabricate Nanocrystalline Titanium Nitride Powders and Their Subsequent Consolidation Using SPS

    Science.gov (United States)

    El-Eskandarany, M. Sherif

    2017-05-01

    The room-temperature reactive ball milling (RBM) approach was employed to synthesize nanostructured fcc-titanium nitride (TiN) powders, starting from milling hcp-titanium (Ti) powders under 10 bar of a nitrogen gas atmosphere, using a roller mill. During the first and intermediate stage of milling, the agglomerated Ti powders were continuously disintegrated into smaller particles with fresh surfaces. Increasing the RBM time led to an increase in the active-fresh surfaces of Ti, resulting increasing of the mole fraction of TiN against unreacted hcp-Ti. Toward the end of the RBM time (20 h), ultrafine spherical powder (with particles 0.5 μm in diameter) of the fcc-TiN phase was obtained, composed of nanocrystalline grains with an average diameter of 8 nm. The samples obtained after different stages of RBM time were consolidated under vacuum at 1600 °C into cylindrical bulk compacts of 20 mm diameter, using spark plasma sintering technique. These compacts that maintained their nanocrystalline characteristics with an average grain size of 56 nm in diameter, possessed high relative density (above 99% of the theoretical density). The Vickers hardness of the as-consolidated TiN was measured and found to be 22.9 GPa. The modulus of elasticity and shear modulus of bulk TiN were measured by a nondestructive test and found to be 384 and 189 GPa, respectively. In addition, the coefficient of friction of the end-product TiN bulk sample was measured and found to be 0.35.

  5. Graded composite diamond coatings with top-layer nanocrystallinity and interfacial integrity: Cross-sectional Raman mapping

    Energy Technology Data Exchange (ETDEWEB)

    Dumpala, Ravikumar [Manufacturing Engineering Section, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Nano Functional Materials Technology Centre, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Ramamoorthy, B. [Manufacturing Engineering Section, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Rao, M.S. Ramachandra, E-mail: msrrao@iitm.ac.in [Nano Functional Materials Technology Centre, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)

    2014-01-15

    Cross-sectional structural characteristics of the CVD diamond coatings deposited on the tungsten carbide (WC-Co) substrates were analysed using Raman imaging technique. The grain size of the nanocrystalline diamond (NCD) coatings was observed to deviate from the nanocrystallinity with increasing thickness and exhibited the surface characteristics of microcrystalline diamond (MCD). However, thick diamond coatings with surface nanocrystallinity is the key requirement for load-bearing tribological applications. Tribological tests have clearly indicated the significance and need for the top-layer nanocrystallinity. Graded composite diamond coatings with an architecture of NCD/transition-layer/MCD/WC-Co are potentail candiadates to realize thick diamond coatings with top-layer nanocrystallinity. Residual stresses along the cross-section of the graded composite diamond coatings were analysed using Raman imaging technique, which confirmed the improved interfacial integrity of the graded composite diamond coatings.

  6. Electrochemical evaluation of corrosion and tribocorrosion behaviour of amorphous and nanocrystalline cobalt–tungsten electrodeposited coatings

    Energy Technology Data Exchange (ETDEWEB)

    Fathollahzade, N.; Raeissi, K., E-mail: k_raeissi@cc.iut.ac.ir

    2014-11-14

    Amorphous and nanocrystalline Co–W coatings were electrodeposited on copper substrates from a citrate–ammonia bath. The coatings showed nodular surface morphologies, but a microcrack network was detected in the amorphous coating. However, a better corrosion resistance was achieved for the amorphous coating. During sliding under open circuit potential (OCP) condition, the potential of amorphous coating gradually became more active probably due to the widening of wear scar, and thus expansion of active area. The amorphous coatings showed a higher volume loss at OCP probably due to its lower microhardness. In anodic sliding, a sharp increase in current density was observed due to mass transport and depassivation effects. In all sliding conditions, the proportion of mass transport was higher than wear accelerated corrosion, which implied that the dissolution reaction of the coatings was mainly a mass-transport controlled process. The results also showed that the effect of sliding on degradation is more intense for the nanocrystalline coating. For both coatings, the formation of the superficial microcracks in the vicinity of wear scars indicating on a surface fatigue wear mechanism. - Highlights: • Mass-transport effect had higher proportion in tribocorrosion of Co–W coatings. • The major electrochemical-wear degradation was for the nanocrystalline coating. • The higher proportion of wear accelerated corrosion was for the amorphous coating. • Superficial microcracks were formed near scars due to the coatings brittleness.

  7. Thermal Residual Stress in Environmental Barrier Coated Silicon Nitride - Modeled

    Science.gov (United States)

    Ali, Abdul-Aziz; Bhatt, Ramakrishna T.

    2009-01-01

    When exposed to combustion environments containing moisture both un-reinforced and fiber reinforced silicon based ceramic materials tend to undergo surface recession. To avoid surface recession environmental barrier coating systems are required. However, due to differences in the elastic and thermal properties of the substrate and the environmental barrier coating, thermal residual stresses can be generated in the coated substrate. Depending on their magnitude and nature thermal residual stresses can have significant influence on the strength and fracture behavior of coated substrates. To determine the maximum residual stresses developed during deposition of the coatings, a finite element model (FEM) was developed. Using this model, the thermal residual stresses were predicted in silicon nitride substrates coated with three environmental coating systems namely barium strontium aluminum silicate (BSAS), rare earth mono silicate (REMS) and earth mono di-silicate (REDS). A parametric study was also conducted to determine the influence of coating layer thickness and material parameters on thermal residual stress. Results indicate that z-direction stresses in all three systems are small and negligible, but maximum in-plane stresses can be significant depending on the composition of the constituent layer and the distance from the substrate. The BSAS and REDS systems show much lower thermal residual stresses than REMS system. Parametric analysis indicates that in each system, the thermal residual stresses can be decreased with decreasing the modulus and thickness of the coating.

  8. Biomimetic helical rosette nanotubes and nanocrystalline hydroxyapatite coatings on titanium for improving orthopedic implants

    Directory of Open Access Journals (Sweden)

    Lijie Zhang

    2008-10-01

    Full Text Available Lijie Zhang1, Yupeng Chen2, Jose Rodriguez3, Hicham Fenniri3, Thomas J Webster11Division of Engineering, 2Department of Chemistry, Brown University, Providence, RI, USA; 3National Institute for Nanotechnology and Department of Chemistry, University of Alberta, Edmonton, AB, CanadaAbstract: Natural bone consists of hard nanostructured hydroxyapatite (HA in a nanostructured protein-based soft hydrogel template (ie, mostly collagen. For this reason, nanostructured HA has been an intriguing coating material on traditionally used titanium for improving orthopedic applications. In addition, helical rosette nanotubes (HRNs, newly developed materials which form through the self-assembly process of DNA base pair building blocks in body solutions, are soft nanotubes with a helical architecture that mimics natural collagen. Thus, the objective of this in vitro study was for the first time to combine the promising attributes of HRNs and nanocrystalline HA on titanium and assess osteoblast (bone-forming cell functions. Different sizes of nanocrystalline HA were synthesized in this study through a wet chemical precipitation process following either hydrothermal treatment or sintering. Transmission electron microscopy images showed that HRNs aligned with nanocrystalline HA, which indicates a high affinity between both components. Some of the nanocrystalline HA formed dense coatings with HRNs on titanium. More importantly, results demonstrated enhanced osteoblast adhesion on the HRN/nanocrystalline HA-coated titanium compared with conventional uncoated titanium. Among all the HRN/nanocrystalline HA coatings tested, osteoblast adhesion was the greatest when HA nanometer particle size was the smallest. In this manner, this study demonstrated for the first time that biomimetic HRN/nanocrystalline HA coatings on titanium were cytocompatible for osteoblasts and, thus, should be further studied for improving orthopedic implants.Keywords: helical rosette nanotubes

  9. Study of the Structural and Mechanical Properties of Nanocrystalline TiAlSiN Gradient Coatings

    NARCIS (Netherlands)

    Cholakova, T.; Chitanov, V.; Chaliampalias, D.; Kolaklieva, L.; Kakanakov, R.; Bahchedjiev, Ch.; Petkov, N.; Pashinski, Ch.; Vourlias, G.; Vouroutzis, N.; Polychroniadis, E.; Wang, Y.; Meletis, E. I.

    2014-01-01

    A study of the structural and mechanical properties of nanocrystalline TiAlSiN gradient coatings deposited by cathodic arc deposition techniques at 500 degrees C and post-annealed at 525 degrees C is presented. Analysis of the coatings, chemical composition and microstructure revealed that the coati

  10. Effects of Bi Addition on the Microstructure and Mechanical Properties of Nanocrystalline Ag Coatings

    Directory of Open Access Journals (Sweden)

    Yuxin Wang

    2017-08-01

    Full Text Available In this study we investigated the effects of Bi addition on the microstructure and mechanical properties of an electrodeposited nanocrystalline Ag coating. Microstructural features were investigated with transmission electron microscopy (TEM. The results indicate that the addition of Bi introduced nanometer-scale Ag-Bi solid solution particles and more internal defects to the initial Ag microstructures. The anisotropic elastic-plastic properties of the Ag nanocrystalline coating with and without Bi addition were examined with nanoindentation experiments in conjunction with the recently-developed inverse method. The results indicate that the as-deposited nanocrystalline Ag coating contained high mechanical anisotropy. With the addition of 1 atomic percent (at% Bi, the anisotropy within Ag-Bi coating was very small, and yield strength of the nanocrystalline Ag-Bi alloy in both longitudinal and transverse directions were improved by over 100% compared to that of Ag. On the other hand, the strain-hardening exponent of Ag-Bi was reduced to 0.055 from the original 0.16 of the Ag coating. Furthermore, the addition of Bi only slightly increased the electrical resistivity of the Ag-Bi coating in comparison to Ag. Results of our study indicate that Bi addition is a promising method for improving the mechanical and physical performances of Ag coating for electrical contacts.

  11. Effects of Bi Addition on the Microstructure and Mechanical Properties of Nanocrystalline Ag Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuxin; Cheng, Guang; Tay, See Leng; Guo, Yuxia; Sun, Xin; Gao, Wei

    2017-08-10

    In this study we investigated the effects of Bi addition on the microstructure and mechanical properties of electrodeposited nanocrystalline Ag coatings. Microstructural features were investigated with transmission electron microscopy (TEM). The results indicate that the addition of Bi introduced nanometer scale Ag-Bi solid solution particles and more internal defects to the initial Ag microstructures. The anisotropic elastoplastic properties of Ag nanocrystalline coatings with and without Bi addition were examined with nanoindentation experiments in conjunction with the recently developed inverse calculation. The results indicate that the as-deposited nanocrystalline Ag coating contained high mechanical anisotropy. With the addition of 1 atomic percent (at.%) Bi, the anisotropy within Ag-Bi coating was very small, and yield strength of nanocrystalline Ag-Bi alloy in both longitudinal and transverse directions were improved by over 100% compared to that of Ag. On the other hand, the strain hardening exponent of Ag-Bi was reduced to 0.055 from the original 0.16 of Ag coating. Furthermore, the addition of Bi only slightly increased the electrical resistivity of the Ag-Bi coating in comparison to Ag. Results of our study indicate that Bi addition is a promising method for improving the physical and mechanical performances of Ag coating for electrical contact.

  12. Effects of Bi Addition on the Microstructure and Mechanical Properties of Nanocrystalline Ag Coatings

    Science.gov (United States)

    Tay, See Leng; Guo, Yunxia; Sun, Xin; Gao, Wei

    2017-01-01

    In this study we investigated the effects of Bi addition on the microstructure and mechanical properties of an electrodeposited nanocrystalline Ag coating. Microstructural features were investigated with transmission electron microscopy (TEM). The results indicate that the addition of Bi introduced nanometer-scale Ag-Bi solid solution particles and more internal defects to the initial Ag microstructures. The anisotropic elastic-plastic properties of the Ag nanocrystalline coating with and without Bi addition were examined with nanoindentation experiments in conjunction with the recently-developed inverse method. The results indicate that the as-deposited nanocrystalline Ag coating contained high mechanical anisotropy. With the addition of 1 atomic percent (at%) Bi, the anisotropy within Ag-Bi coating was very small, and yield strength of the nanocrystalline Ag-Bi alloy in both longitudinal and transverse directions were improved by over 100% compared to that of Ag. On the other hand, the strain-hardening exponent of Ag-Bi was reduced to 0.055 from the original 0.16 of the Ag coating. Furthermore, the addition of Bi only slightly increased the electrical resistivity of the Ag-Bi coating in comparison to Ag. Results of our study indicate that Bi addition is a promising method for improving the mechanical and physical performances of Ag coating for electrical contacts. PMID:28796189

  13. Boron coating on boron nitride coated nuclear fuels by chemical vapor deposition

    Science.gov (United States)

    Durmazuçar, Hasan H.; Gündüz, Güngör

    2000-12-01

    Uranium dioxide-only and uranium dioxide-gadolinium oxide (5% and 10%) ceramic nuclear fuel pellets which were already coated with boron nitride were coated with thin boron layer by chemical vapor deposition to increase the burn-up efficiency of the fuel during reactor operation. Coating was accomplished from the reaction of boron trichloride with hydrogen at 1250 K in a tube furnace, and then sintering at 1400 and 1525 K. The deposited boron was identified by infrared spectrum. The morphology of the coating was studied by using scanning electron microscope. The plate, grainy and string (fiber)-like boron structures were observed.

  14. Zirconium nitride hard coatings; Revestimentos protetores de nitreto de zirconio

    Energy Technology Data Exchange (ETDEWEB)

    Roman, Daiane; Amorim, Cintia Lugnani Gomes de; Soares, Gabriel Vieira; Figueroa, Carlos Alejandro; Baumvol, Israel Jacob Rabin; Basso, Rodrigo Leonardo de Oliveira [Universidade de Caxias do Sul (UCS), Caxias do Sul, RS (Brazil)

    2010-07-01

    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)

  15. Anti-corrosive and anti-microbial properties of nanocrystalline Ni-Ag coatings

    Energy Technology Data Exchange (ETDEWEB)

    Raghupathy, Y.; Natarajan, K.A.; Srivastava, Chandan, E-mail: csrivastava@materials.iisc.ernet.in

    2016-04-15

    Graphical abstract: - Highlights: • Electrodeposition yielded phase-segregated, nanocrystalline Ni-Ag coatings. • Ni-Ag alloys exhibited smaller Ni crystals compared to pure Ni. • Ultra fine Ni grains of size 12–14 nm favoured Ni-Ag solid solution. • Nanocrystalline Ag resisted bio-fouling by Sulphate Reducing bacteria. • Ni-Ag outperformed pure Ni in corrosion and bio-corrosion tests. - Abstract: Anti-corrosive and anti-bacterial properties of electrodeposited nanocrystalline Ni-Ag coatings are illustrated. Pure Ni, Ni-7 at.% Ag, & Ni-14 at.% Ag coatings were electrodeposited on Cu substrate. Coating consisted of Ni-rich and Ag-rich solid solution phases. With increase in the Ag content, the corrosion resistance of the Ni-Ag coating initially increased and then decreased. The initial increase was due to the Ni-Ag solid solution. The subsequent decrease was due to the increased galvanic coupling between the Ag-rich and Ni-rich phases. For all Ag contents, the corrosion resistance of the Ni-Ag coating was higher than the pure Ni coating. Exposure to Sulphate Reducing Bacteria (SRB) revealed that the extent of bio-fouling decreased with increase in the Ag content. After 2 month exposure to SRB, the Ni-Ag coatings demonstrated less loss in corrosion resistance (58% for Ni-7 at.% Ag and 20% for Ni-14 at.% Ag) when compared pure Ni coating (115%).

  16. Wettability and corrosion of alumina embedded nanocomposite MAO coating on nanocrystalline AZ31B magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gheytani, M.; Aliofkhazraei, M., E-mail: maliofkh@gmail.com; Bagheri, H.R.; Masiha, H.R.; Rouhaghdam, A. Sabour

    2015-11-15

    In this paper, micro- and nanocrystalline AZ31B magnesium alloy were coated by micro-arc oxidation method. In order to fabricate nanocrystalline surface layer, surface mechanical attrition treatment was performed and nano-grains with average size of 5–10 nm were formed on the surface of the samples. Coating process was carried out at different conditions including two coating times and two types of electrolyte. Alumina nanoparticles were utilized as suspension in electrolyte to form nanocomposite coatings by micro-arc oxidation method. Potentiodynamic polarization, percentage of porosity, and wettability tests were performed to study various characteristics of the coated samples. The results of scanning electron microscope imply that samples coated in silicate-based electrolyte involve much lower surface porosity (∼25%). Besides, the results of wettability test indicated that the maximum surface tension with deionized water is for nanocrystalline sample. In this regard, the sample coated in silicate-based suspension was 4 times more hydrophilic than the microcrystalline sample. - Highlights: • MAO in phosphate electrolyte needs higher energy as compared to silicate electrolyte. • Less porosity and finer grain size on free surface of the silicate-based coatings. • Observed porosity from top surface of coating shows the effect of the final MAO sparks. • SMAT affects surface roughness and accelerates growth kinetics.

  17. Boron nitride nanosheet coatings with controllable water repellency.

    Science.gov (United States)

    Pakdel, Amir; Zhi, Chunyi; Bando, Yoshio; Nakayama, Tomonobu; Golberg, Dmitri

    2011-08-23

    The growth, structure, and properties of two-dimensional boron nitride (BN) nanostructures synthesized by a thermal chemical vapor deposition method have been systematically investigated. Most of the BN nanosheets (BNNSs) were less than 5 nm in thickness, and their purity was confirmed by X-ray energy dispersive spectroscopy, X-ray photoelectron spectroscopy, electron energy loss spectroscopy, and Raman spectroscopy. The effects of the process variables on the morphology and roughness of the coatings were studied using atomic force microscopy and scanning electron microscopy. A smooth BN coating was obtained at 900 °C, while compact BNNS coatings composed of partially vertically aligned nanosheets could be achieved at 1000 °C and higher temperatures. These nanosheets were mostly separated and exhibited high surface area especially at higher synthesis temperatures. The nonwetting properties of the BNNS coatings were independent of the water pH and were examined by contact angle goniometry. The present results enable a convenient growth of pure BNNS coatings with controllable levels of water repellency, ranging from partial hydrophilicity to superhydrophobicity with contact angles exceeding 150°. © 2011 American Chemical Society

  18. 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.

  19. Studies on Tribological Behavior of Aluminum Nitride-Coated Steel

    Science.gov (United States)

    Ionescu, G. C.; Nae, I.; Ripeanu, R. G.; Dinita, A.; Stan, G.

    2017-02-01

    The new opportunities introduced by the large development of the IoT (internet of things) are increasing the demand for sensors to be located as close as possible to the supervised process. The Aluminum Nitride (AIN) is one of the most promising materials for sensors due to its piezoelectric, excellent mechanical properties, chemical inertness and high melting point. Due to these material properties, the AlN sensors are suitable to operate in high temperature and harsh environment conditions and therefore are very promising to be employed in industrial applications. In this article are presented the studies conducted on several Aluminum Nitride-Coated Steel structures with the goal of producing sensors embedded in the ball bearings, bearings and other mobile parts of machine tools. The experiments were conducted on simple coatings structures without lubricating materials and the obtained results are promising, demonstrating that, with some limitations the AIN could be used in such applications. This paper was accepted for publication in Proceedings after double peer reviewing process but was not presented at the Conference ROTRIB’16

  20. Study of titanium nitride for low-e coating application

    Institute of Scientific and Technical Information of China (English)

    ZHENG PengFei; ZHAO GaoLing; ZHANG TianBo; WU LiQing; WANG JianXun; HAN GaoRong

    2007-01-01

    The paper reports our novel work on chemical vapor deposition coating of titanium nitride (TiN) thin film on glass for energy saving. TiN films were deposited on glass substrates by atmospheric pressure chemical vapor deposition (APCVD) using titanium tetrachloride (TiCl4) and ammonia (NH3) as precursors. As a result,TiN films with a thickness of 500 nm were obtained. X-ray diffraction (XRD),scanning electron microscopy (SEM),atomic force microscopy (AFM),four-point probe method and optical spectroscopy were respectively employed to study the crystallization, microstructure,surface morphology,electrical and optical properties of the coated TiN films. The deposited TiN films are of NaCl structure with a preferred (200) orientation. The particles in the film are uniform. The reflectivity of the TiN coating in the near-infrared (NIR) band can reach over 40%,the visible transmittance is approximately 60%,and the visible reflectivity is lower than 10%. The sheet electrical resistance is 34.5 Ω. According to Drude theory,the lower sheet resistance of 34.5 Ω gives a high reflectivity of 71.5% around middle-far infrared band. The coated films exhibit good energy-saving performance.

  1. Titanium-nitride-oxide-coated coronary stents: insights from the available evidence.

    Science.gov (United States)

    Karjalainen, Pasi P; Nammas, Wail

    2017-06-01

    Coating of stent surface with a biocompatible material is suggested to improve stent safety profile. A proprietary process was developed to coat titanium-nitride-oxide on the stent surface, based on plasma technology that uses the nano-synthesis of gas and metal. Preclinical in vitro and in vivo investigation confirmed blood compatibility of titanium (nitride-) oxide films. Titanium-nitride-oxide-coated stents demonstrated a better angiographic outcome, compared with bare-metal stents at mid-term follow-up; however, they failed to achieve non-inferiority for angiographic outcome versus second-generation drug-eluting stents. Observational studies showed adequate clinical outcome at mid-term follow-up. Non-randomized studies showed an outcome of titanium-nitride-oxide-coated stents comparable to - or better than - first-generation drug-eluting stents at long-term follow-up. Two randomized controlled trials demonstrated comparable efficacy outcome, and a better safety outcome of titanium-nitride-oxide-coated stents versus drug-eluting stents at long-term follow-up. Evaluation by optical coherence tomography at mid-term follow-up revealed better neointimal strut coverage associated with titanium-nitride-oxide-coated stents versus drug-eluting stents; yet, neointimal hyperplasia thickness was greater. Key messages Stents coated with titanium-nitride-oxide demonstrated biocompatibility in preclinical studies: they inhibit platelet and fibrin deposition, and reduce neointimal growth. In observational and non-randomized studies, titanium-nitride-oxide-coated stents were associated with adequate safety and efficacy outcome. In randomized trials of patients with acute coronary syndrome, titanium-nitride-oxide-coated stents were associated with a better safety outcome, compared with drug-eluting stents; efficacy outcome was comparable.

  2. Effects of crystalline growth on corrosion behaviour of nanocrystalline NiAl coating

    Indian Academy of Sciences (India)

    M Tavoosi; H Heydari; A Hosseinkhani; B Adelimoghaddam

    2015-08-01

    In the current work, the effect of crystalline growth on the corrosion behaviour of nanocrystalline NiAl coating was investigated. In this regard, NiAl coatings with different crystalline sizes in the range of 20–110 nm were produced by mechanical alloying, high-velocity oxy-fuel processing (HVOF) and isothermal annealing at 600°C for 0–30 h. The produced and annealed samples were characterized using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The corrosion behaviours of coatings were examined in NaCl 3/5% electrolyte by potentiostat analysis. The nanocrystalline NiAl coating with the average crystalline size of about 20 nm and the porosity content of about 2% was successfully produced by mechanical alloying and HVOF processing. By annealing the coating, the NiAl crystalline sizes increased sharply, approaching a constant value of about 110 nm. It was found that the corrosion resistance of nanocrystalline coating increased with the increase in the crystalline size.

  3. A Galvanostatic Modeling for Preparation of Electrodeposited Nanocrystalline Coatings by Control of Current Density

    Institute of Scientific and Technical Information of China (English)

    Ali Mohammad Rashidi

    2012-01-01

    The correlation between the grain size of electrodeposited coatings and the current densities was modeled by considering galvanostatic conditions. In order to test the model by experimental results, nanocrystalline (NC) nickel samples were deposited at different current densities using a Watts bath. The grain size of the deposits was evaluated by X-ray diffraction (XRD) technique. Model predictions were validated by finding a curve being the best-fit to the experimental results which were gathered from literature for different NC coatings in addition to those data measured in this research for NC nickel coatings. According to our model, the variation of grain size with the reciprocal of the current density follows a power law. A good agreement between the experimental results and model predictions was observed which indicated that the derived analytical model is applicable for producting the nanocrystalline electrodeposits with the desired grain size by controling current density.

  4. Hot Corrosion Behavior of Sputtered Nanocrystalline Coating with Yttrium Addition at 900 °C

    Directory of Open Access Journals (Sweden)

    Wei Jiang

    2014-04-01

    Full Text Available The high temperature corrosion behavior of sputtered nanocrystalline K38 coating with and without yttrium addition under mixed molten salt film in air was investigated. Accelerated corrosion occurred on the coating without yttrium (Y addition locally after 60 h exposure at 900 °C, which resulted in negative weight gain in kinetics. A uniform and protective alumina scale formed on surface of the coating containing yttrium in comparison. Y enriched particle as corrosion product was observed on the top of alumina scale. The results indicated the beneficial influence of Y on the chemical stability of the protective scale in the presence of chloride. The mechanism was discussed.

  5. Tribology of nitriding layer, TiN coatings and their complex on AISI D2 steel

    Institute of Scientific and Technical Information of China (English)

    WANG Ke-sheng; ZHANG De-yuan; DONG Ding-fu

    2004-01-01

    The sliding wear and impact wear resistances of D2 steel with nitriding layer, PVD titanium nitride coating and their duplex treatment were investigated. The experimental results suggest that the duplex treatment has the best sliding and impact wear resistances under experimental conditions. And the wear resistance of PVD titanium nitride is better than that of nitriding. The impact wear resistance and wear mechanism of all three surface layers remain unchanged under impact load of 0.2 J or 1 J. All samples end with the same symptom of flaking.

  6. Shear-induced phase transition of nanocrystalline hexagonal boron nitride to wurtzitic structure at room temperature and lower pressure.

    Science.gov (United States)

    Ji, Cheng; Levitas, Valery I; Zhu, Hongyang; Chaudhuri, Jharna; Marathe, Archis; Ma, Yanzhang

    2012-11-20

    Disordered structures of boron nitride (BN), graphite, boron carbide (BC), and boron carbon nitride (BCN) systems are considered important precursor materials for synthesis of superhard phases in these systems. However, phase transformation of such materials can be achieved only at extreme pressure-temperature conditions, which is irrelevant to industrial applications. Here, the phase transition from disordered nanocrystalline hexagonal (h)BN to superhard wurtzitic (w)BN was found at room temperature under a pressure of 6.7 GPa after applying large plastic shear in a rotational diamond anvil cell (RDAC) monitored by in situ synchrotron X-ray diffraction (XRD) measurements. However, under hydrostatic compression to 52.8 GPa, the same hBN sample did not transform to wBN but probably underwent a reversible transformation to a high-pressure disordered phase with closed-packed buckled layers. The current phase-transition pressure is the lowest among all reported direct-phase transitions from hBN to wBN at room temperature. Usually, large plastic straining leads to disordering and amorphization; here, in contrast, highly disordered hBN transformed to crystalline wBN. The mechanisms of strain-induced phase transformation and the reasons for such a low transformation pressure are discussed. Our results demonstrate a potential of low pressure-room temperature synthesis of superhard materials under plastic shear from disordered or amorphous precursors. They also open a pathway of phase transformation of nanocrystalline materials and materials with disordered and amorphous structures under extensive shear.

  7. Shear-induced phase transition of nanocrystalline hexagonal boron nitride to wurtzitic structure at room temperature and lower pressure

    Science.gov (United States)

    Ji, Cheng; Levitas, Valery I.; Zhu, Hongyang; Chaudhuri, Jharna; Marathe, Archis; Ma, Yanzhang

    2012-01-01

    Disordered structures of boron nitride (BN), graphite, boron carbide (BC), and boron carbon nitride (BCN) systems are considered important precursor materials for synthesis of superhard phases in these systems. However, phase transformation of such materials can be achieved only at extreme pressure–temperature conditions, which is irrelevant to industrial applications. Here, the phase transition from disordered nanocrystalline hexagonal (h)BN to superhard wurtzitic (w)BN was found at room temperature under a pressure of 6.7 GPa after applying large plastic shear in a rotational diamond anvil cell (RDAC) monitored by in situ synchrotron X-ray diffraction (XRD) measurements. However, under hydrostatic compression to 52.8 GPa, the same hBN sample did not transform to wBN but probably underwent a reversible transformation to a high-pressure disordered phase with closed-packed buckled layers. The current phase-transition pressure is the lowest among all reported direct-phase transitions from hBN to wBN at room temperature. Usually, large plastic straining leads to disordering and amorphization; here, in contrast, highly disordered hBN transformed to crystalline wBN. The mechanisms of strain-induced phase transformation and the reasons for such a low transformation pressure are discussed. Our results demonstrate a potential of low pressure–room temperature synthesis of superhard materials under plastic shear from disordered or amorphous precursors. They also open a pathway of phase transformation of nanocrystalline materials and materials with disordered and amorphous structures under extensive shear. PMID:23129624

  8. The effect of different titanium nitride coatings on the adhesion of Candida albicans to titanium.

    Science.gov (United States)

    Wang, Jing; An, Yanxin; Liang, Haifeng; Tong, Yu; Guo, Tianwen; Ma, Chufan

    2013-10-01

    The aim of the present study was an in vitro evaluation of the effects of different titanium nitride (TiNx) coatings on Candida albicans (C. albicans) adhesion to titanium and to correlate these findings to differences in specific surface characteristics (surface topography, roughness, chemical component, and surface free energy). TiNx coatings were prepared by physical vapour deposition (PVD), a plasma nitriding process or a dual nitriding process. Surface properties were analysed by the optical stereoscopic microscopy, scanning electron microscopy, roughmeter, and drop shape methods. Quantity comparisons of C. albicans on the four surfaces were assessed by cell count and XTT reduction assays. Types of adhesive C. albicans were explored by SEM and confocal laser scanning microscope. The nitrided modifications were found to influence the surface properties and fungal susceptivity of flat titanium. Compared to flat titanium, fewer adhered C. albicans in yeast form were observed on the TiN-coated surface, whereas the plasma nitrided surface did not show any reduced potential to adhere C. albicans in hyphal or yeast form. The dual nitrided coating showed anti-fungal characteristics, although a small quantity of hyphae were identified. Our findings indicate that the Ti2N phase is prone to C. albicans hyphae, while the TiN phase inhibits their adhesion. Different TiNx phases could influence the characteristics of C. albicans adhesion. TiN coating by PVD could be a potential modification to inhibit C. albicans. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. The effect of yttrium addition on oxidation of a sputtered nanocrystalline coating with moderate amount of tantalum in composition

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jinlong [Corrosion and Protection Laboratory, Key Laboratory of Superlight Materials and Surface Technology (Harbin Engineering University), Ministry of Education, Harbin 150001 (China); Laboratory of Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Chen, Minghui, E-mail: mhchen@imr.ac.cn [Laboratory of Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Yang, Lanlan; Liu, Li; Zhu, Shenglong [Laboratory of Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wang, Fuhui [Corrosion and Protection Laboratory, Key Laboratory of Superlight Materials and Surface Technology (Harbin Engineering University), Ministry of Education, Harbin 150001 (China); Laboratory of Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Meng, Guozhe [Corrosion and Protection Laboratory, Key Laboratory of Superlight Materials and Surface Technology (Harbin Engineering University), Ministry of Education, Harbin 150001 (China)

    2016-03-15

    Graphical abstract: - Highlights: • Effect of Y addition on oxidation of nanocrystalline coating is studied. • Y addition delays transformation of q-Al{sub 2}O{sub 3} to a-Al{sub 2}O{sub 3} during oxidation. • Y addition prevents scale rumpling. • Y segregates at grain boundaries of the nanocrystalline coating. • Y retards the transportation of Ta thus reduces its oxidation. - Abstract: The effect of yttrium addition on isothermal oxidation at 1050 °C of a sputtered nanocrystalline coating with moderate amount of tantalum in composition was investigated. Results indicate that yttrium addition delays transformation of metastable θ-Al{sub 2}O{sub 3} to equilibrium α-Al{sub 2}O{sub 3} grown on the nanocrystalline coatings. It prevents scale rumpling and promotes the formation of oxide pegs at interface between the oxide scale and the underlying coating. Besides, yttrium prefers to segregate at grain boundaries of the nanocrystalline coating and retards the outward transportation of tantalum from coating to oxide scale, thus reducing the excessive oxidation of tantalum.

  10. Thermal stability of sputtered nanocrystalline hard coatings; Thermische Stabilitaet gesputterter nanokristalliner Hartstoffschichten

    Energy Technology Data Exchange (ETDEWEB)

    Willmann, H.; Mayrhofer, P.H.; Mitterer, C. [Inst. fuer Metallkunde und Werkstoffpruefung, Montanuniversitaet Leoben, Leoben (Austria); Beschliesser, M. [Materials Center Leoben, Leoben (Austria)

    2004-08-01

    This article deals with the thermal stability of magnetron sputtered hard coatings, i.e. their resistance against oxidation and recrystallization, depending on their chemical compositions. The oxidation behaviour of films in the chromium-nitrogen system was studied by thermogravimetric measurements at different temperatures. Dynamic differential scanning calorimetry was employed to characterize the recrystallization behaviour and the succeeding grain growth. The investigated samples were multiphase nanocrystalline coatings within the titanium-boron-nitrogen system. In addition, the film structures and grain sizes prior to and after the thermal analysis were investigated by means of X-ray diffraction (XRD). (orig.)

  11. Improving nanocrystalline diamond coatings for micro end mills

    Science.gov (United States)

    Heaney, Patrick J.

    A new method is presented for coating 300 mum diameter tungsten carbide (WC) micro end mills with diamond using a hot filament chemical vapor deposition (HF-CVD) method. This method has been developed to create uniform, conformal and continuous diamond coatings. Initial work is shown to prove the feasibility and concept of the project. This was the first work known to coat and evaluate the machining performance WC micro end mills. The performance of uncoated and coated micro end mills was evaluated by dry machining channels in 6061-T6 aluminum. The test results showed a 75% and 90% decrease in both cutting and trust forces for machining, respectfully. The coated tools produced a more predictable surface finish with no burring. These improved results are due to the superior tribological properties of diamond against aluminum. Initial results indicated severe problems with coating delamination causing complete tool failure. After proving the initial concept, new methods for optimizing the coating and improving performance were studied. Each optimization step is monitored through surface analysis techniques to monitor changes in coating morphology and diamond quality. Nucleation density was increased by improving the seed method, using ultra dispersed diamond (UDD) seed. The increase in nucleation density allowed the synthesis of coatings as thin as 60 nm. The adhesion of the coating to the tool was improved through carbon ion implantation (CII). CII is a different surface preparation technique that deactivates the effect of Co, while not weakening the tool. CII also creates a great nucleation layer which diamond can directly grow from, allowing the diamond coating to chemically bond to the substrate improving adhesion and eliminating the need for a seed layer. These thin coatings were shown to be of high quality sp3 trigonaly bonded diamond that resulted in lower machining forces with less delamination. The 90% reduction in machining forces that thin conformal

  12. Laser fabrication nanocrystalline coatings using simultaneous powders/wire feed

    Science.gov (United States)

    Li, Jianing; Zhai, Tongguang; Zhang, Yuanbin; Shan, Feihu; Liu, Peng; Ren, Guocheng

    2016-07-01

    Laser melting deposition (LMD) fabrication is used to investigate feasibilty of simultaneously feeding TC17 wire and the Stellite 20-Si3N4-TiC-Sb mixed powders in order to increase the utilization ratio of materials and also quality of LMD composite coatings on the TA1 substrate. SEM images indicated that such LMD coating with metallurgical joint to substrate was formed free of the obvious defects. Lots of the ultrafine nanocrystals (UNs) were produced, which distributed uniformly in some coating matrix location, retarding growth of the ceramics in a certain extent; UNs were intertwined with amorphous, leading the yarn-shape materials to be produced. Compared with substrate, an improvement of wear resistance was achieved for such LMD coating.

  13. Electrochemical passivation behaviour of nanocrystalline Fe80Si20 coating in borate buffer solution

    Indian Academy of Sciences (India)

    G Gupta; A P Moon; K Mondal

    2013-02-01

    Passivation behaviour of nanocrystalline coating (Fe80Si20) obtained by in situ mechanical alloying route is studied and compared with that of the commercial pure iron and cast Fe80Si20 in sodium borate buffer solution at two different pH values (7.7 and 8.4). The coating reveals single passivation at a pH of 7.7 and double stage passivity at a pH of 8.4. The first passive layer is due to the dissolution mechanism and second passivity is related to stable passivation. The cast sample shows single stage passivity in the solution of pH 8.4. The difference in the passivation behaviour for the cast alloy (Fe80Si20) and the coating is related to the presence of highly iron-enriched localized regions, formed during the processing stage of coating.

  14. Grain size refinement in nanocrystalline Hitperm-type glass-coated microwires

    Energy Technology Data Exchange (ETDEWEB)

    Talaat, A. [Departamento de Física de Materiales, UPV/EHU, 20018 San Sebastián (Spain); Departamento de Física Aplicada, EUPDS, UPV/EHU, 20018 San Sebastián (Spain); Val, J.J. del [Departamento de Física de Materiales, UPV/EHU, 20018 San Sebastián (Spain); Zhukova, V. [Departamento de Física de Materiales, UPV/EHU, 20018 San Sebastián (Spain); Departamento de Física Aplicada, EUPDS, UPV/EHU, 20018 San Sebastián (Spain); Ipatov, M. [Departamento de Física de Materiales, UPV/EHU, 20018 San Sebastián (Spain); Klein, P.; Varga, R. [Institute of Physics, Faculty of Science, University of Pavol Jozef Safarik, Park Angelinum 9, 04154 Kosice (Slovakia); González, J. [Departamento de Física de Materiales, UPV/EHU, 20018 San Sebastián (Spain); Churyukanova, M. [National University of Science and Technology “MISIS”, Moscow 119049 (Russian Federation); Zhukov, A., E-mail: arkadi.joukov@ehu.es [Departamento de Física de Materiales, UPV/EHU, 20018 San Sebastián (Spain); Departamento de Física Aplicada, EUPDS, UPV/EHU, 20018 San Sebastián (Spain); IKERBASQUE, Basque Foundation for Science, 48011 Bilbao (Spain)

    2016-05-15

    We present a new-Fe{sub 38.5}Co{sub 38.5}B{sub 18}Mo{sub 4}Cu{sub 1} Hitperm glass-coated microwires obtained by Taylor-Ulitovsky technique with nanocrystalline structure consisting of about 23 nm of BCC α-FeCo and an amorphous precursors in as-prepared samples. Annealing resulted in a considerable decrease of such nano-grains down to (11 nm). Obtained results are discussed in terms of the stress diffusion of limited crystalline growth and the chemical composition. Rectangular hysteresis loops have been observed on all annealed samples that are necessary conditions to obtain fast domain wall propagation. An enhancement of the domain wall velocity as well as mobility after annealing has been obtained due to the structural relaxation of such grains with positive magnetostriction. These structure benefits found in the nanocrystalline Hitperm glass-coated microwires are promising for developing optimal magnetic properties. - Highlights: • Grains size refinement upon annealing. • Enhancement of the domain wall velocity as well as mobility after annealing. • Nanocrystalline structure in as-prepared microwires.

  15. Nanocrystalline β-Ta Coating Enhances the Longevity and Bioactivity of Medical Titanium Alloys

    Directory of Open Access Journals (Sweden)

    Linlin Liu

    2016-09-01

    Full Text Available A β-Ta nanocrystalline coating was engineered onto a Ti-6Al-4V substrate using a double cathode glow discharge technique to improve the corrosion resistance and bioactivity of this biomedical alloy. The new coating has a thickness of ~40 μm and exhibits a compact and homogeneous structure composed of equiaxed β-Ta grains with an average grain size of ~22 nm, which is well adhered on the substrate. Nanoindentation and scratch tests indicated that the β-Ta coating exhibited high hardness combined with good resistance to contact damage. The electrochemical behavior of the new coating was systematically investigated in Hank’s physiological solution at 37 °C. The results showed that the β-Ta coating exhibited a superior corrosion resistance as compared to uncoated Ti-6Al-4V and commercially pure tantalum, which was attributed to a stable passive film formed on the β-Ta coating. The in vitro bioactivity was studied by evaluating the apatite-forming capability of the coating after seven days of immersion in Hank’s physiological solution. The β-Ta coating showed a higher apatite-forming ability than both uncoated Ti-6Al-4V and commercially pure Ta, suggesting that the β-Ta coating has the potential to enhance functionality and increase longevity of orthopaedic implants.

  16. Investigation of Amorphous/Nanocrystalline Iron-Based Thermal Barrier Coatings

    Science.gov (United States)

    Bobzin, K.; Öte, M.; Königstein, T.

    2017-02-01

    Because of their favorable thermophysical properties, good machinability and low material costs, iron-based coatings which exhibit a highly amorphous/nanocrystalline microstructure are currently in the focus of research. Considering the crystallization temperature of the material, iron-based coatings might be the next generation of thermal barrier coatings (TBCs) for low-temperature systems, reducing thermal losses. The objective of this research project is the development of highly amorphous, iron-based coatings. For this purpose, amorphous feedstock materials with different chromium contents have been developed and characterized regarding their microstructures, phase compositions, crystallization temperatures and amorphous content. The results show that the amorphous content is reduced with increasing particle size and chromium content. The coatings were deposited by air plasma spraying (APS) and high-velocity oxygen fuel spraying (HVOF). It is shown that all coatings exhibit amorphous structures. HVOF coatings show a smaller amount of amorphous content compared to the feedstock materials, indicating crystallization occurring in not fully melted particles or insufficient rapid cooling. The APS process can increase the amount of amorphous content compared to the feedstock material, as shown for x Cr = 15%. All coatings proof good thermal shock behavior. Lowest thermal diffusivity values were determined for APS coatings, which confirms the potential of iron-based TBCs.

  17. Investigation of Amorphous/Nanocrystalline Iron-Based Thermal Barrier Coatings

    Science.gov (United States)

    Bobzin, K.; Öte, M.; Königstein, T.

    2017-01-01

    Because of their favorable thermophysical properties, good machinability and low material costs, iron-based coatings which exhibit a highly amorphous/nanocrystalline microstructure are currently in the focus of research. Considering the crystallization temperature of the material, iron-based coatings might be the next generation of thermal barrier coatings (TBCs) for low-temperature systems, reducing thermal losses. The objective of this research project is the development of highly amorphous, iron-based coatings. For this purpose, amorphous feedstock materials with different chromium contents have been developed and characterized regarding their microstructures, phase compositions, crystallization temperatures and amorphous content. The results show that the amorphous content is reduced with increasing particle size and chromium content. The coatings were deposited by air plasma spraying (APS) and high-velocity oxygen fuel spraying (HVOF). It is shown that all coatings exhibit amorphous structures. HVOF coatings show a smaller amount of amorphous content compared to the feedstock materials, indicating crystallization occurring in not fully melted particles or insufficient rapid cooling. The APS process can increase the amount of amorphous content compared to the feedstock material, as shown for x Cr = 15%. All coatings proof good thermal shock behavior. Lowest thermal diffusivity values were determined for APS coatings, which confirms the potential of iron-based TBCs.

  18. Microstructure and corrosion behavior of electrodeposited nano-crystalline nickel coating on AZ91 Mg alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zarebidaki, Arman, E-mail: arman.zare@iauyazd.ac.ir; Mahmoudikohani, Hassan, E-mail: hassanmahmoudi.k@gmail.com; Aboutalebi, Mohammad-Reza

    2014-12-05

    Highlights: • Activation, zincating, and Cu electrodeposition were used as pretreatment processes for electrodeposition of nickel coatings. • Nano-crystalline nickel coatings were successfully electrodeposited onto the AZ91 Mg alloys. • Effect of nickel electrodeposited coating on the corrosion resistance of AZ91 Mg alloy has been studied. - Abstract: In order to enhance the corrosion resistance, nickel coating was electrodeposited onto AZ91 Mg alloy. Activation, zincating, and Cu electrodeposition used as pretreatment processes for better adhesion and corrosion performance of the nickel over layer. The corrosion properties of the AZ91 Mg alloy, nickel electroplated AZ91 Mg alloy, and pure nickel was assessed via polarization and electrochemical impedance spectroscopy (EIS) methods in 3.5 wt% NaCl solution. Moreover, the structure of the coating was investigated by means of X-ray diffraction, whereas specimen’s morphology and elemental composition were analyzed using scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS). Measurements revealed that the coating has a nano-crystalline structure with the grain size of 95 nm. Corrosion results showed superior corrosion resistance for the coated AZ91 Mg alloy as the corrosion current density decreased from 2.5 × 10{sup −4} A cm{sup −2}, for the uncoated sample, to 1.5 × 10{sup −5} A cm{sup −2}, for coated specimen and the corrosion potential increased from −1.55 V to −0.98 V (vs. Ag/AgCl) at the same condition.

  19. Effect of nanocrystalline surface of substrate on microstructure and wetting of PEO coatings

    Indian Academy of Sciences (India)

    H R Masiha; H R Bagheri; M Gheytani; M Aliofkhazraei; A Sabour Rouhaghdam; T Shahrabi

    2015-08-01

    In this research, effect of surface mechanical attrition treatment (SMAT) was studied on characteristics of the coatings formed using plasma electrolyte oxidation (PEO) on AA1230 aluminium. To do so, first, the samples were coated with and without SMAT pre-process. Coating by PEO method was carried out in two phosphate-based and silicate-based suspensions of silicon nitride nanoparticles for 10 min. Next, to study the distribution of the nanoparticles and elements inside the coating, surface morphology of the samples was examined using scanning electron microscopy and energy dispersive spectroscopy. In addition, wettability test was performed on all samples using the deionized water. Also, droplet expansion manner on the porous oxide coating surface and its relation with fine structure of the coating was investigated. The results indicated that samples coated in silicate-based electrolyte have a relatively rougher microstructure as compared to samples coated in phosphate-based electrolyte. The average surface pores area percentage of the samples coated in silicate-based electrolytes was 13.9% greater than that of samples coated in phosphate-based electrolyte. Moreover, the average height to diameter (h/d) value obtained from wettability test for samples coated in silicate-based electrolyte was 13.3% greater than that of phosphate-based electrolyte.

  20. 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.

  1. Secondary electron yield from stainless steel surface coated with titanium nitride

    Science.gov (United States)

    Orlov, O. S.; Meshkov, I. N.; Rudakov, A. Yu.; Philippov, A. V.

    2014-09-01

    The experiment on measurement of secondary electron yield from surface of a stainless steel Kh189 sample covered with titanium nitride is performed at stand "Recuperator". This work is related to known problem of electron clouds formation in a vacuum chamber by a propagating charge particle beam. An original method of secondary electron yield measurement was developed in this experiment. The obtained results allow one to estimate efficiency of coating nitride titanium.

  2. 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.

  3. Silicon nitride coated silicon thin film on three dimensions current collector for lithium ion battery anode

    Science.gov (United States)

    Wu, Cheng-Yu; Chang, Chun-Chi; Duh, Jenq-Gong

    2016-09-01

    Silicon nitride coated silicon (N-Si) has been synthesized by two-step DC sputtering on Cu Micro-cone arrays (CMAs) at ambient temperature. The electrochemical properties of N-Si anodes with various thickness of nitride layer are investigated. From the potential window of 1.2 V-0.05 V, high rate charge-discharge and long cycle test have been executed to investigate the electrochemical performances of various N-Si coated Si-based lithium ion batteries anode materials. Higher specific capacity can be obtained after 200 cycles. The cycling stability is enhanced via thinner nitride layer coating as silicon nitride films are converted to Li3N with covered Si thin films. These N-Si anodes can be cycled under high rates up to 10 C due to low charge transfer resistance resulted from silicon nitride films. This indicates that the combination of silicon nitride and silicon can effectively endure high current and thus enhance the cycling stability. It is expected that N-Si is a potential candidate for batteries that can work effectively under high power.

  4. Studies on Nanocrystalline TiN Coatings Prepared by Reactive Plasma Spraying

    Directory of Open Access Journals (Sweden)

    Dong Yanchun

    2008-01-01

    Full Text Available Titanium nitride (TiN coatings with nanostructure were prepared on the surface of 45 steel (Fe-0.45%C via reactive plasma spraying (denoted as RPS Ti powders using spraying gun with self-made reactive chamber. The microstructural characterization, phases constitute, grain size, microhardness, and wear resistance of TiN coatings were systematically investigated. The grain size was obtained through calculation using the Scherrer formula and observed by TEM. The results of X-ray diffraction and electron diffraction indicated that the TiN is main phase of the TiN coating. The forming mechanism of the nano-TiN was characterized by analyzing the SEM morphologies of surface of TiN coating and TiN drops sprayed on the surface of glass, and observing the temperature and velocity of plasma jet using Spray Watch. The tribological properties of the coating under nonlubricated condition were tested and compared with those of the AISI M2 high-speed steel and Al2O3 coating. The results have shown that the RPS TiN coating presents better wear resistance than the M2 high-speed steel and Al2O3 coating under nonlubricated condition. The microhardness of the cross-section and longitudinal section of the TiN coating was tested. The highest hardness of the cross-section of TiN coating is 1735.43HV100 g.

  5. Simulation and experimental study of CVD process for low temperature nanocrystalline silicon carbide coating

    Energy Technology Data Exchange (ETDEWEB)

    Kaushal, Amit; Prakash, Jyoti, E-mail: jprakash@barc.gov.in; Dasgupta, Kinshuk; Chakravartty, Jayanta K.

    2016-07-15

    Highlights: • Parametric simulation was carried out for specially designed CVD reactor. • Effect of fluid velocity, heat flow and concentration were studied in CVD reactor. • Coating study carried out using low temperature and environmental safe CVD process. • Dense and uniform nanocrystalline SiC film was coated on zircaloy substrate. - Abstract: There is a huge requirement for development of a coating technique in nuclear industry, which is environmentally safe, economical and applicable to large scale components. In this view, simulation of gas-phase behavior in specially designed CVD reactor was carried out using computational tool, COMSOL. There were two important zones in CVD reactor first one is precursor vaporization zone and second one is coating zone. Optimized parameters for coating were derived from the simulation of gas phase dynamics in both zone of CVD reactor. The overall effect of fluid velocity, heat flow and concentration profile showed that Re = 54 is the optimum reaction condition for uniform coating in CVD system. In CVD coating experiments a synthesized halogen free, non-toxic and non-corrosive silicon carbide precursor was used. Uniform coating of SiC was obtained on zircaloy substrate at 900 °C using as synthesized organosilicon precursor. The X-ray diffraction and scanning electron microscopy analysis show that dense nano crystalline SiC film was deposited on zircaloy substrate.

  6. Recent progress in the synthesis and characterization of amorphous and crystalline carbon nitride coatings

    CERN Document Server

    Widlow, I

    2000-01-01

    This review summarizes our most recent findings in the structure and properties of amorphous and crystalline carbon nitride coatings, synthesized by reactive magnetron sputtering. By careful control of the plasma conditions via proper choice of process parameters such as substrate bias, target power and gas pressure, one can precisely control film structure and properties. With this approach, we were able to produce amorphous carbon nitride films with controlled hardness and surface roughness. In particular, we can synthesize ultrathin (1 nm thick) amorphous carbon nitride films to be sufficiently dense and uniform that they provide adequate corrosion protection for hard disk applications. We demonstrated the strong correlation between ZrN (111) texture and hardness in CN sub x /ZrN superlattice coatings. Raman spectroscopy and near-edge X-ray absorption show the predominance of sp sup 3 -bonded carbon in these superlattice coatings.

  7. Nanocrystalline lanthanide nitride materials synthesised by thermal treatment of amido and ammine metallocenes: X-ray studies and DFT calculations.

    Science.gov (United States)

    Baisch, Ulrich; Pagano, Sandro; Zeuner, Martin; Barros, Noémi; Maron, Laurent; Schnick, Wolfgang

    2006-06-14

    The decomposition process of ammine lanthanide metallocenes was studied by X-ray diffractometry, spectroscopy and theoretical investigations. A series of ammine-tris(eta(5)-cyclopentadienyl)lanthanide(III) complexes 1-Ln (Lanthanide (Ln)=Sm, Gd, Dy, Ho, Er, Yb) was synthesised by the reaction of [Cp(3)Ln] complexes (Cp=cyclopentadienyl) with liquid ammonia at -78 degrees C and structurally characterised by X-ray diffraction methods, mass spectrometry and vibrational (IR, Raman) spectroscopy. Furthermore, amido-bis(eta(5)-cyclopentadienyl)lanthanide(III) complexes 2-Ln (Ln=Dy, Ho, Er, Yb) were synthesised by heating the respective ammine adduct 1-Ln in an inert gas atmosphere at temperatures of between 240 and 290 degrees C. X-ray diffraction studies, mass spectrometry and vibrational (IR, Raman) spectroscopy were carried out for several 2-Ln species and proved the formation of dimeric mu(2)-bridged compounds. Species 1-Ln are highly reactive coordination compounds and showed different behaviour regarding the decomposition to 2-Ln. The reaction of 1-Ln and 2-Ln with inorganic bases yielded lanthanide nitride LnN powders with an estimated crystallite size of between 40 and 90 nm at unprecedented low temperatures of 240 to 300 degrees C. Temperature-dependent X-ray powder diffraction and transmission electron microscopy (TEM) investigations were performed and showed that the decomposition reaction yielded nanocrystalline material. Structural optimisations were carried out for 1-Ln and 2-Ln by employing density functional (DFT) calculations. A good agreement was found between the observed and calculated structural parameters. Also, Gibbs free energies were calculated for 1-Ln, 2-Ln and the pyrolysis reaction to the nitride material, and were found to fit well with the expected ranges.

  8. Nanocrystalline, superhard, ductile ceramic coatings for roller-cone bit bearings

    Energy Technology Data Exchange (ETDEWEB)

    Namavar, F.; Colter, P.; Karimy, H. [Spire Corp., Bedford, MA (United States)] [and others

    1997-12-31

    The established method for construction of roller bits utilizes carburized steel, frequently with inserted metal bearing surfaces. This construction provides the necessary surface hardness while maintaining other desirable properties in the core. Protective coatings are a logical development where enhanced hardness, wear resistance, corrosion resistance, and surface properties are required. The wear properties of geothermal roller-cone bit bearings could be further improved by application of protective ceramic hard coatings consisting of nanometer-sized crystallites. Nanocrystalline protective coatings provide the required combination of hardness and toughness which has not been available thus far using traditional ceramics having larger grains. Increased durability of roller-cone bit bearings will ultimately reduce the cost of drilling geothermal wells through increased durability.

  9. Marine corrosion protective coatings of hexagonal boron nitride thin films on stainless steel.

    Science.gov (United States)

    Husain, Esam; Narayanan, Tharangattu N; Taha-Tijerina, Jose Jaime; Vinod, Soumya; Vajtai, Robert; Ajayan, Pulickel M

    2013-05-22

    Recently, two-dimensional, layered materials such as graphene and hexagonal boron nitride (h-BN) have been identified as interesting materials for a range of applications. Here, we demonstrate the corrosion prevention applications of h-BN in marine coatings. The performance of h-BN/polymer hybrid coatings, applied on stainless steel, were evaluated using electrochemical techniques in simulated seawater media [marine media]. h-BN/polymer coating shows an efficient corrosion protection with a low corrosion current density of 5.14 × 10(-8) A/cm(2) and corrosion rate of 1.19 × 10(-3) mm/year and it is attributed to the hydrofobic, inert and dielectric nature of boron nitride. The results indicated that the stainless steel with coatings exhibited improved corrosion resistance. Electrochemical impedance spectroscopy and potentiodynamic analysis were used to propose a mechanism for the increased corrosion resistance of h-BN coatings.

  10. Sputtered tungsten-based ternary and quaternary layers for nanocrystalline diamond deposition.

    Science.gov (United States)

    Walock, Michael J; Rahil, Issam; Zou, Yujiao; Imhoff, Luc; Catledge, Shane A; Nouveau, Corinne; Stanishevsky, Andrei V

    2012-06-01

    Many of today's demanding applications require thin-film coatings with high hardness, toughness, and thermal stability. In many cases, coating thickness in the range 2-20 microm and low surface roughness are required. Diamond films meet many of the stated requirements, but their crystalline nature leads to a high surface roughness. Nanocrystalline diamond offers a smoother surface, but significant surface modification of the substrate is necessary for successful nanocrystalline diamond deposition and adhesion. A hybrid hard and tough material may be required for either the desired applications, or as a basis for nanocrystalline diamond film growth. One possibility is a composite system based on carbides or nitrides. Many binary carbides and nitrides offer one or more mentioned properties. By combining these binary compounds in a ternary or quaternary nanocrystalline system, we can tailor the material for a desired combination of properties. Here, we describe the results on the structural and mechanical properties of the coating systems composed of tungsten-chromium-carbide and/or nitride. These WC-Cr-(N) coatings are deposited using magnetron sputtering. The growth of adherent nanocrystalline diamond films by microwave plasma chemical vapor deposition has been demonstrated on these coatings. The WC-Cr-(N) and WC-Cr-(N)-NCD coatings are characterized with atomic force microscopy and SEM, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and nanoindentation.

  11. Effects of nanotopography on the in vitro hemocompatibility of nanocrystalline diamond coatings.

    Science.gov (United States)

    Skoog, Shelby A; Lu, Qijin; Malinauskas, Richard A; Sumant, Anirudha V; Zheng, Jiwen; Goering, Peter L; Narayan, Roger J; Casey, Brendan J

    2017-01-01

    Nanocrystalline diamond (NCD) coatings have been investigated for improved wear resistance and enhanced hemocompatibility of cardiovascular devices. The goal of this study was to evaluate the effects of NCD surface nanotopography on in vitro hemocompatibility. NCD coatings with small (NCD-S) and large (NCD-L) grain sizes were deposited using microwave plasma chemical vapor deposition and characterized using scanning electron microscopy, atomic force microscopy, contact angle testing, and Raman spectroscopy. NCD-S coatings exhibited average grain sizes of 50-80 nm (RMS 5.8 nm), while NCD-L coatings exhibited average grain sizes of 200-280 nm (RMS 23.1 nm). In vitro hemocompatibility testing using human blood included protein adsorption, hemolysis, nonactivated partial thromboplastin time, platelet adhesion, and platelet activation. Both NCD coatings demonstrated low protein adsorption, a nonhemolytic response, and minimal activation of the plasma coagulation cascade. Furthermore, the NCD coatings exhibited low thrombogenicity with minimal platelet adhesion and aggregation, and similar morphological changes to surface-bound platelets (i.e., activation) in comparison to the HDPE negative control material. For all assays, there were no significant differences in the blood-material interactions of NCD-S versus NCD-L. The two tested NCD coatings, regardless of nanotopography, had similar hemocompatibility profiles compared to the negative control material (HDPE) and should be further evaluated for use in blood-contacting medical devices. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 253-264, 2017.

  12. Pressure-induced phase transition of nanocrystalline iron sulphide coated by polyvinyl alcohol

    CERN Document Server

    Gao Wei; Kan-Shihai; Pan Yue Wu; Wang Xin; Zou Guang Tian; LiuJing

    2002-01-01

    Nanocrystalline iron sulphide (FeS) coated with polyvinyl alcohol, with particle size ranging from several to several tens of nanometres, has been prepared by the chemical precipitation synthesis method. The phase transition of FeS has been investigated by using in situ high-pressure diffraction with synchrotron radiation at pressures up to 42.5 GPa. Most of the diffraction lines are broadened and weakened. At the pressure of 11.8 GPa, a new phase transition was observed. However, only eleven x-ray reflections were recorded under high pressure; the crystal structure is unknown.

  13. 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.

  14. Use of Acoustic Emission During Scratch Testing for Understanding Adhesion Behavior of Aluminum Nitride Coatings

    Science.gov (United States)

    Choudhary, R. K.; Mishra, P.

    2016-06-01

    In this work, acoustic emission during scratch testing of the aluminum nitride coatings formed on stainless steel substrate by reactive magnetron sputtering was analyzed to assess the coating failure. The AlN coatings were formed under the variation of substrate temperature, substrate bias potential, and discharge power. The coatings deposited in the temperature range of 100 to 400 °C showed peak acoustic emission less than 1.5%, indicating ductile nature of the coating. However, for coatings formed with substrate negative bias potential of 20 to 50 V, numerous sharp acoustic bursts with maximum emission approaching 80% were observed, indicating brittle nature of the coatings with large number of defects present. The shift in the intensity of the first major acoustic peak toward higher load, with the increasing bias potential, confirmed improved adhesion of the coating. Also, the higher discharge power resulted in increased acoustic emission.

  15. Ultrananocrystalline Diamond-Coated Microporous Silicon Nitride Membranes for Medical Implant Applications

    Science.gov (United States)

    Skoog, Shelby A.; Sumant, Anirudha V.; Monteiro-Riviere, Nancy A.; Narayan, Roger J.

    2012-04-01

    Ultrananocrystalline diamond (UNCD) exhibits excellent biological and mechanical properties, which make it an appropriate choice for promoting epidermal cell migration on the surfaces of percutaneous implants. We deposited a ~150 nm thick UNCD film on a microporous silicon nitride membrane using microwave plasma chemical vapor deposition. Scanning electron microscopy and Raman spectroscopy were used to examine the pore structure and chemical bonding of this material, respectively. Growth of human epidermal keratinocytes on UNCD-coated microporous silicon nitride membranes and uncoated microporous silicon nitride membranes was compared using the 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide (MTT) assay. The results show that the UNCD coating did not significantly alter the viability of human epidermal keratinocytes, indicating potential use of this material for improving skin sealing around percutaneous implants.

  16. Characterization of nanocrystalline ZnO:Al films by sol-gel spin coating method

    Energy Technology Data Exchange (ETDEWEB)

    Gareso, P. L., E-mail: pgareso@gmail.com; Rauf, N., E-mail: pgareso@gmail.com; Juarlin, E., E-mail: pgareso@gmail.com [Department of Physics, Faculty of Mathematics and Natural Sciences, Hasanuddin University, Makassar 90245 (Indonesia); Sugianto,; Maddu, A. [Department of Physics, Faculty of Mathematics and Natural Sciences, Bogor Institute of Culture, IPB Bogor (Indonesia)

    2014-09-25

    Nanocrystalline ZnO films doped with aluminium by sol-gel spin coating method have been investigated using optical transmittance UV-Vis and X-ray diffraction (X-RD) measurements. ZnO films were prepared using zinc acetate dehydrate (Zn(CH{sub 3}COO){sub 2}@@‡2H{sub 2}O), ethanol, and diethanolamine (DEA) as a starting material, solvent, and stabilizer, respectively. For doped films, AlCl{sub 3} was added to the mixture. The ZnO:Al films were deposited on a transparent conductive oxide (TCO) substrate using spin coating technique at room temperature with a rate of 3000 rpm in 30 sec. The deposited films were annealed at various temperatures from 400°C to 600°C during 60 minutes. The transmittance UV-Vis measurement results showed that after annealing at 400°C, the energy band gap profile of nanocrystalline ZnO:Al film was a blue shift. This indicated that the band gap of ZnO:Al increased after annealing due to the increase of crystalline size. As the annealing temperature increased the bandgap energy was a constant. In addition to this, there was a small oscillation occurring after annealing compared to the as–grown samples. In the case of X-RD measurements, the crystalinity of the films were amorphous before annealing, and after annealing the crystalinity became enhance. Also, X-RD results showed that structure of nanocrystalline ZnO:Al films were hexagonal polycrystalline with lattice parameters are a = 3.290 Å and c = 5.2531 Å.

  17. Plasma assisted metal-organic chemical vapor deposition of hard chromium nitride thin film coatings using chromium(III) acetylacetonate as the precursor

    Energy Technology Data Exchange (ETDEWEB)

    Dasgupta, Arup; Kuppusami, P.; Lawrence, Falix; Raghunathan, V.S.; Antony Premkumar, P.; Nagaraja, K.S

    2004-06-15

    A new technique has been developed for depositing hard nanocrystalline chromium nitride (CrN) thin films on metallic and ceramic substrates using plasma assisted metal-organic chemical vapor deposition (PAMOCVD) technique. In this low temperature and environment-friendly process, a volatile mixture of chromium(III) acetylacetonate and either ammonium iodide or ammonium bifluoride were used as precursors. Nitrogen and hydrogen have been used as the gas precursors. By optimizing the processing conditions, a maximum deposition rate of {approx}0.9 {mu}m/h was obtained. A comprehensive characterization of the CrN films was carried out using X-ray diffraction (XRD), microhardness, and microscopy. The microstructure of the CrN films deposited on well-polished stainless steel (SS) showed globular particles, while a relatively smooth surface morphology was observed for coatings deposited on polished yittria-stabilized zirconia (YSZ)

  18. Hexagonal Boron Nitride Nanosheets as High-Performance Binder-Free Fire-Resistant Wood Coatings.

    Science.gov (United States)

    Liu, Juanjuan; Kutty, Rajendrannair Govindan; Zheng, Qingshen; Eswariah, Varrla; Sreejith, Sivaramapanicker; Liu, Zheng

    2017-01-01

    Hexagonal boron nitride (h-BN) nanosheets are synthesized through a facile shear force liquid phase exfoliation method and their use as a binder-free oxidation and fire-resistant wood coating is demonstrated. Characterized by intrinsic low thermal diffusivity and thermal effusivity, h-BN nanosheet coatings show an excellent fire resistance and oxidation resistance up to 900 °C in air.

  19. Biomimetic nanocrystalline apatite coatings synthesized by Matrix Assisted Pulsed Laser Evaporation for medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Visan, A. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Grossin, D. [CIRIMAT – Carnot Institute, University of Toulouse, ENSIACET, 4 Allée Emile Monso, 31030 Toulouse Cedex 4 (France); Stefan, N.; Duta, L.; Miroiu, F.M. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Stan, G.E. [National Institute of Materials Physics, RO-077125, Magurele-Ilfov (Romania); Sopronyi, M.; Luculescu, C. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Freche, M.; Marsan, O.; Charvilat, C. [CIRIMAT – Carnot Institute, University of Toulouse, ENSIACET, 4 Allée Emile Monso, 31030 Toulouse Cedex 4 (France); Ciuca, S. [Politehnica University of Bucharest, Faculty of Materials Science and Engineering, Bucharest (Romania); Mihailescu, I.N., E-mail: ion.mihailescu@inflpr.ro [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania)

    2014-02-15

    Highlights: • We report the deposition by MAPLE of biomimetic apatite coatings on Ti substrates. • This is the first report of MAPLE deposition of hydrated biomimetic apatite films. • Biomimetic apatite powder was synthesized by double decomposition process. • Non-apatitic environments, of high surface reactivity, are preserved post-deposition. • We got the MAPLE complete transfer as thin film of a hydrated, delicate material. -- Abstract: We report the deposition by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique of biomimetic nanocrystalline apatite coatings on titanium substrates, with potential application in tissue engineering. The targets were prepared from metastable, nanometric, poorly crystalline apatite powders, analogous to mineral bone, synthesized through a biomimetic approach by double decomposition process. For the deposition of thin films, a KrF* excimer laser source was used (λ = 248 nm, τ{sub FWHM} ≤ 25 ns). The analyses revealed the existence, in synthesized powders, of labile non-apatitic mineral ions, associated with the formation of a hydrated layer at the surface of the nanocrystals. The thin film analyses showed that the structural and chemical nature of the nanocrystalline apatite was prevalently preserved. The perpetuation of the non-apatitic environments was also observed. The study indicated that MAPLE is a suitable technique for the congruent transfer of a delicate material, such as the biomimetic hydrated nanohydroxyapatite.

  20. Optimization of nanocrystalline -alumina coating for direct spray water-cooling of optical devices

    Indian Academy of Sciences (India)

    S N Alam; M Anaraky; Z Shafeizadeh; P J Parbrook

    2014-12-01

    In this study, aluminium oxide films were deposited on BK7 glass substrates using radio frequencymagnetron sputtering. The purposes of this study are to clarify the influence of O2 flow as reactive partial gas, which is necessary to form Al2O3 films, and then the influence of substrate temperature on structure and rigidity of coatings towards water injection. The fabricated metal oxide films were characterized using techniques such as atomic force microscopy (AFM), X-ray diffraction (XRD), spectrophotometry, ellipsometry and Rutherford backscattering (RBS) analysis. Modifications of the partial gas percentage influences the optical properties and composition of the deposited aluminium oxide, the best samples being those deposited with 5% and 8% oxygen. The substrate temperature affects the structure and crystallization of the films. Nanocrystalline -Al2O3 has been observed at temperatures above 300 °C with the grain size of 25 nm. After water injection, there was a large diversity in the surface roughness of samples with different substrate temperature. Experiments have shown that the best resistance against water injection occurs for the sample deposited at 350 °C with 5%partial gas. We conclude that the rigidity of nanocrystalline -Al2O3 coatings can be explained by both Hall–Petch and Coble creep mechanism. In this case, there is an optimum grain size of around 42 nm against water spray.

  1. The effect of He and swift heavy ions on nanocrystalline zirconium nitride

    Energy Technology Data Exchange (ETDEWEB)

    Janse van Vuuren, A., E-mail: arnojvv@gmail.com [Centre for HRTEM, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Neethling, J.H. [Centre for HRTEM, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Skuratov, V.A. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Uglov, V.V. [Belarusian State University, Minsk (Belarus); Petrovich, S. [VINCA Institute of Nuclear Sciences, Belgrade University, Belgrade (Serbia)

    2014-05-01

    Recent studies have shown that swift heavy ion irradiation may significantly modulate hydrogen and helium behaviour in some materials. This phenomenon is of considerable practical interest for ceramics in general and also for candidate materials for use as inert matrix fuel hosts. These materials will accumulate helium via (n, α) reactions and will also be subjected to irradiation by fission fragments. Cross-sectional transmission electron microscopy and scanning electron microscopy was used to study nanocrystalline ZrN irradiated with 30 keV He to fluences between 10{sup 16} and 5 × 10{sup 16} cm{sup −2}, 167 MeV Xe to fluences between 5 × 10{sup 13} and 10{sup 14} cm{sup −2} and also 695 MeV Bi to a fluence of 1.5 × 10{sup 13} cm{sup −2}. He/Bi and He/Xe irradiated samples were annealed at temperatures between 600 and 1000 °C and were analysed using SEM, XTEM and selected area diffraction. The results indicated that post irradiation heat treatment induces exfoliation at a depth that corresponds to the end-of-range of 30 keV He ions. SEM and XTEM analysis of He/Xe irradiated samples revealed that electronic excitation effects, due to Xe ions, suppress helium blister formation and consequently the exfoliation processes. He/Bi samples however do not show the same effects. This suggests that nanocrystalline ZrN is prone to the formation of He blisters which may ultimately lead material failure. These effects may however be mitigated by electronic excitation effects from certain SHIs.

  2. Ti-WC nanocrystalline coating formed by surface mechanical attrition treatment process on 316L stainless steel.

    Science.gov (United States)

    Aliofkhazraei, M; Rouhaghdam, A Sabour; Ghobadi, E

    2011-10-01

    Nanocrystalline coatings were performed on the surface of 316L stainless steel plates mechanically with a mixture of Ti and WC powders under vacuum conditions. The targets were replaced in the end of the high energy milling rig, while Ti-WC mixture was milled as usual. It is shown that the coatings are nanocrystalline in nature with narrow distribution of average size of nanocrystallites. X-ray diffraction and scanning electron microscopy (with energy-dispersive spectrometer) revealed that the top layer of the coatings is uniform. Microhardness, roughness and primary corrosion tests (tafel tests) proved enhancement of coated samples with respect to raw materials. Transmission electron microscope image of deformed surface confirmed surrounding of nanoparticles by dislocation loops after plastic deformation.

  3. Plasma synthesis and HPHT consolidation of BN nanoparticles, nanospheres, and nanotubes to produce nanocrystalline cubic boron nitride

    Science.gov (United States)

    Stout, Christopher

    Plasma methods offer a variety of advantages to nanomaterials synthesis. The process is robust, allowing varying particle sizes and phases to be generated simply by modifying key parameters. The work here demonstrates a novel approach to nanopowder synthesis using inductively-coupled plasma to decompose precursor, which are then quenched to produce a variety of boron nitride (BN)-phase nanoparticles, including cubic phase, along with short-range-order nanospheres (e.g., nano-onions) and BN nanotubes. Cubic BN (c-BN) powders can be generated through direct deposition onto a chilled substrate. The extremely-high pyrolysis temperatures afforded by the equilibrium plasma offer a unique particle growth environment, accommodating long deposition times while exposing resulting powders to temperatures in excess of 5000K without any additional particle nucleation and growth. Such conditions can yield short-range ordered amorphous BN structures in the form of 20nm diameter nanospheres. Finally, when introducing a rapid-quenching counter-flow gas against the plasma jet, high aspect ratio nanotubes are synthesized, which are collected on substrate situated radially. The benefits of these morphologies are also evident in high-pressure/high-temperature consolidation experiments, where nanoparticle phases can offer a favorable conversion route to super-hard c-BN while maintaining nanocrystallinity. Experiments using these morphologies are shown to begin to yield c-BN conversion at conditions as low as 2.0 GPa and 1500°C when using micron sized c-BN seeding to create localized regions of high pressures due to Hertzian forces acting on the nanoparticles.

  4. Simulation of mechanical properties and residual stress of nanostructural coatings based on transition metals nitrides

    Science.gov (United States)

    Danilyuk, Alexander L.; Shaposhnikov, Victor L.; Filonov, Andrew B.; Anischik, Victor M.; Uglov, Vladimir V.; Kuleshov, Andrew K.; Danilyuk, Maxim A.

    2008-07-01

    Physical properties of novel nanostructural coatings, formed by ion-plasmous flux from solid solutions of transition and refractory metals (Ti, Zr, Cr) have been intensively studied to enhance characteristics of tool materials. We have developed the modeling technique for effective predictions of internal stresses and calculation of elastic properties of nanostructural coatings composed of metal nitrides. Quantum-mechanical modeling of microstructure, elastic constants, bulk modulus and residual stress for binary and ternary metal nitride clusters have been performed. The dependences of these characteristics on the crystal structure deformations have been investigated. The essential modification of elastic constants and bulk moduli with changes in lattice constants and stoichiometric composition has been observed. The influence of elastically stressed state of sample on X-ray diffraction intensity has been examined by using the exponential model. The model of residual stress distribution identifying in depth of wear-resistant nanostructural coating from the data of diffraction experiments has been developed.

  5. Tungsten nitride coatings obtained by HiPIMS as plasma facing materials for fusion applications

    Science.gov (United States)

    Tiron, Vasile; Velicu, Ioana-Laura; Porosnicu, Corneliu; Burducea, Ion; Dinca, Paul; Malinský, Petr

    2017-09-01

    In this work, tungsten nitride coatings with nitrogen content in the range of 19-50 at% were prepared by reactive multi-pulse high power impulse magnetron sputtering as a function of the argon and nitrogen mixture and further exposed to a deuterium plasma jet. The elemental composition, morphological properties and physical structure of the samples were investigated by Rutherford backscattering spectrometry, atomic force microscopy and X-ray diffraction. Deuterium implantation was performed using a deuterium plasma jet and its retention in nitrogen containing tungsten films was investigated using thermal desorption spectrometry. Deuterium retention and release behaviour strongly depend on the nitrogen content in the coatings and the films microstructure. All nitride coatings have a polycrystalline structure and retain a lower deuterium level than the pure tungsten sample. Nitrogen content in the films acts as a diffusion barrier for deuterium and leads to a higher desorption temperature, therefore to a higher binding energy.

  6. Thermal conductivity of titanium aluminum silicon nitride coatings deposited by lateral rotating cathode arc

    Energy Technology Data Exchange (ETDEWEB)

    Samani, M.K., E-mail: majid1@e.ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Surface Technology Group, Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore); CINTRA-CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore 637553 (Singapore); Ding, X.Z. [Surface Technology Group, Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore); Amini, S. [School of Materials Science and Engineering. Nanyang Technological University, 50 Nanyang Avenue, Singapore (Singapore); Khosravian, N.; Cheong, J.Y. [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Chen, G. [BC Photonics Technological Company, 5255 Woodwards Rd., Richmond, BC V7E 1G9 (Canada); Tay, B.K. [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); CINTRA-CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore 637553 (Singapore)

    2013-06-30

    A series of physical vapour deposition titanium aluminum silicon nitride nanocomposite coating with a different (Al + Si)/Ti atomic ratio, with a thickness of around 2.5 μm were deposited on stainless steel substrate by a lateral rotating cathode arc process in a flowing nitrogen atmosphere. The composition and microstructure of the as-deposited coatings were analyzed by energy dispersive X-ray spectroscopy, and X-ray diffraction, and cross-sectional scanning electron microscopy observation. The titanium nitride (TiN) coating shows a clear columnar structure with a predominant (111) preferential orientation. With the incorporation of Al and Si, the crystallite size in the coatings decreased gradually, and the columnar structure and (111) preferred orientation disappeared. Thermal conductivity of the as-deposited coating samples at room temperature was measured by using pulsed photothermal reflectance technique. Thermal conductivity of the pure TiN coating is about 11.9 W/mK. With increasing the (Al + Si)/Ti atomic ratio, the coatings' thermal conductivity decreased monotonously. This reduction of thermal conductivity could be ascribed to the variation of coatings' microstructure, including the decrease of grain size and the resultant increase of grain boundaries, the disruption of columnar structure, and the reduced preferential orientation. - Highlights: • A series of titanium aluminum silicon nitride with different (Al + Si)/Ti atomic ratio were deposited on Fe304. • The composition and microstructure of the as-deposited coatings were analyzed. • Thermal conductivity of the samples was measured by pulsed photothermal reflectance. • With increasing the (Al + Si)/Ti atomic ratio, thermal conductivity decreased. • Reduction of thermal conductivity is ascribed to the variation of its microstructure.

  7. Production of Nanocrystalline Ni-20Cr Coatings for High-Temperature Applications

    Science.gov (United States)

    Kumar, Manoj; Singh, Harpreet; Singh, Narinder

    2014-04-01

    Presynthesized nanocrystalline Ni-20Cr powder was deposited on SA 516 and T91 boiler steels by a high-velocity oxy-fuel spraying process. Ni-20Cr powder was synthesized by the ball milling approach. The high-temperature oxidation behavior of bare and coated samples was then studied under cyclic isothermal conditions at 900 °C for 50 cycles. The kinetics of oxidation was established using weight change measurements for the bare and coated boiler steels. Uncoated and coated samples of T91 steel were exposed to the superheated zone of a power plant boiler at 750 °C under cyclic conditions for 15 cycles. Each cycle consisted of 100 h of heating followed by 1 h of cooling. Attempts were made to study the kinetics of erosion-corrosion using weight change and thickness loss data for the samples. Different characterization techniques were used to study the oxidized and eroded-corroded samples, including x-ray diffraction, scanning electron microscopy/energy-dispersive spectroscopy, and x-ray mapping analyses. The Ni-20Cr alloy powder coating was found to offer excellent oxidation resistance to the base steels and was successful in reducing the weight gain of SA 516 steel by 98.5 % and that of T91 steel by 65 %. The coating was observed to reduce the erosion-corrosion rate of T91 steel by 86 % in terms of thickness loss. This indicates that the investigated nanostructured coating can be a better choice over conventional coating for erosion-corrosion control of boiler tubes.

  8. Tapered Optical Fiber Humidity Sensor Coated with Nano-crystalline ZnO Doped with KCI

    Directory of Open Access Journals (Sweden)

    Sivacoumar Rajalingam

    2015-03-01

    Full Text Available In this research study we have targeted to fabricate a tapered optical fiber coated with zinc oxide doped with KCl to improve the humidity sensing capability of zinc oxide. The optical fiber was tapered through chemical etching method by HF acid (49.5%. The nano-crystalline Zinc Oxide (ZnO was synthesized using single molecular precursor method doped with KCl. The resulting material was characterized with Fourier Transform Infrared spectroscopy (FTIR, X-Ray Diffractometry (XRD and Scanning Electron Microscopy (SEM. The sensing mechanism of this sensor is based on the change of the optical properties of the coating when the relative humidity increases. The humidity sensing characteristic has been estimated by measuring the Optical Permeability (OP as a function of percentage of Relative Humidity (%RH in the ranging from 5 to 98% inside a closed chamber. The tapered optical fiber tested with an overlay coating at the optimal working point achieves better sensitivity. The experimental results show that the 5.7 wt% KCl doped ZnO nano-fibers hold super-rapid response and recovery than normal ZnO coating.

  9. The Structure and Properties of Pulsed dc Sputtered Nanocrystalline NbN Coatings for Proton Exchange Membrane Fuel Cell.

    Science.gov (United States)

    Chun, Sung-Yong

    2016-02-01

    Niobium nitride coatings for the surface modified proton exchange membrane fuel cells with various pulse parameters have been prepared using dc (direct current) and asymmetric-bipolar pulsed dc magnetron sputtering. The pulse frequency and the duty cycle were varied from 5 to 50 kHz and 50 to 95%, respectively. The deposition rate, grain size and resistivity of pulsed dc sputtered films were decreased when the pulse frequency increased, while the nano hardness of niobium nitride films increased. We present in detail coatings (e.g., deposition rate, grain size, prefer-orientation, resistivity and hardness). Our studies show that niobium nitride coatings with superior properties can be prepared using asymmetric-bipolar pulsed dc sputtering.

  10. Deposition of nanocrystalline nonstoichiometric chromium oxide coatings on the surface of multiwalled carbon nanotubes by chromium acetylacetonate vapor pyrolysis

    Science.gov (United States)

    Kremlev, K. V.; Ob'edkov, A. M.; Ketkov, S. Yu.; Kaverin, B. S.; Semenov, N. M.; Gusev, S. A.; Andreev, P. V.

    2017-04-01

    Nanocrystalline coatings of nonstoichiometric chromium oxide have been obtained for the first time on the surface of multiwalled carbon nanotubes (MWCNTs) by the method of metalorganic chemical-vapor deposition using chromium acetylacetonate as a precursor. The new hybrid nanomaterial (Cr2O2.4/MWCNT) has been characterized by X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis. It is established that oxidation of the hybrid nanomaterial in air under soft conditions (at 380°C) leads to the formation of nanocrystalline chromium oxide (Cr2O3) on the surface of MWCNTs.

  11. Analysis of hardness of nanocrystalline coatings of aluminum-rich Ti1−AlN

    Indian Academy of Sciences (India)

    J Hernández-Torres; L García-González; L Zamora-Peredo; T Hernández-Quiroz; A Sauceda-Carvajal; P J García-Ramírez; N Flores-Ramírez

    2012-10-01

    Titanium aluminum nitride coatings were fabricated by a d.c.magnetron sputtering system from a Ti–Al (60/40wt%) target. Coatings were deposited on steel substrates, at a substrate temperature of 250 °C and a bias voltage of –80 V. The nitrogen flow was varied from 1.5–6 sccm and the Ar flow was kept constant at 20 sccm. The morphology and microstructure of the coatings were analysed by X-ray diffraction and scanning electron microscopy. The results of X-ray diffraction showed the presence of two cubic crystalline phases, TiN and AlN, which were confirmed by X-ray photoelectron spectroscopy. The Vicker hardness was obtained by the effective model of indentation. It was observed that the hardness of the coatings decreases from 22.8–9.5 GPa with an increased nitrogen content from 1.5–4.5 sccm. Subsequently, the hardness increased to 22.1 GPa by increasing nitrogen to 6 sccm. The behavior of hardness with grain size variation is consistent with the Hall-Peth relationship. The high value in the hardness of the coatings is mainly attributed to small grain sizes and the compressive stress present.

  12. Formation of boron nitride coatings on silicon carbide fibers using trimethylborate vapor

    Science.gov (United States)

    Yuan, Mengjiao; Zhou, Tong; He, Jing; Chen, Lifu

    2016-09-01

    High quality boron nitride (BN) coatings have been grown on silicon carbide (SiC) fibers by carbothermal nitridation and at atmospheric pressure. SiC fibers were first treated in chlorine gas to form CDC (carbide-derived carbon) film on the fiber surface. The CDC-coated SiC fibers were then reacted with trimethylborate vapor and ammonia vapor at high temperature, forming BN coatings by carbothermal reduction. The FT-IR, XPS, XRD, SEM, TEM and AES were used to investigate the formation of the obtained coatings. It has been found that the obtained coatings are composed of phase mixture of h-BN and amorphous carbon, very uniform in thickness, have smooth surface and adhere well with the SiC fiber substrates. The BN-coated SiC fibers retain ∼80% strength of the as-received SiC fibers and show an obvious interfacial debonding and fiber pullout in the SiCf/SiOC composites. This method may be useful for the large scale production of high quality BN coating on silicon carbide fiber.

  13. Formation of boron nitride coatings on silicon carbide fibers using trimethylborate vapor

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Mengjiao; Zhou, Tong; He, Jing; Chen, Lifu, E-mail: lfchen@xmu.edu.cn

    2016-09-30

    High quality boron nitride (BN) coatings have been grown on silicon carbide (SiC) fibers by carbothermal nitridation and at atmospheric pressure. SiC fibers were first treated in chlorine gas to form CDC (carbide-derived carbon) film on the fiber surface. The CDC-coated SiC fibers were then reacted with trimethylborate vapor and ammonia vapor at high temperature, forming BN coatings by carbothermal reduction. The FT-IR, XPS, XRD, SEM, TEM and AES were used to investigate the formation of the obtained coatings. It has been found that the obtained coatings are composed of phase mixture of h-BN and amorphous carbon, very uniform in thickness, have smooth surface and adhere well with the SiC fiber substrates. The BN-coated SiC fibers retain ∼80% strength of the as-received SiC fibers and show an obvious interfacial debonding and fiber pullout in the SiC{sub f}/SiOC composites. This method may be useful for the large scale production of high quality BN coating on silicon carbide fiber.

  14. [Effect of titanium nitride coating on bacterial corrosion resistance of dental Co-Cr alloy].

    Science.gov (United States)

    Zou, Jie; Chen, Jie; Hu, Bin

    2010-04-01

    To study the influence of titanium nitride(TiN) coating on bacterial corrosion resistance of clinically used Co-Cr alloy. The Co-Cr alloy commonly used for casting metal full crown was casted with specimen 10mm x 10mm x 3mm in size. The specimen was coated with a thickness of 2.5 microm TiN coating on the surface by multi-arc physical vapor deposition. Then the specimen before and after coating titanium nitride were exposed to TSB media with S.mutans or Actinomyces viscosus,while pure media,as control.After inoculated for 24 hours, the Tafel polarization curves of the specimen were measured by electrochemical station. From the Tafel polarization curves, the non-coated Co-Cr alloy showed that corrosion potential moved to the negative way in presence of oral bacteria,and passivation interval got shorter.While the polarization curves of the specimen after coating TiN changed slightly in presence of oral microorganism. The TiN significantly weakened the corrosion action of bacteria on the alloy. These results demonstrate that the TiN coating with better tolerance to the bacterial action can improve bacterial corrosion resistance of Co-Cr alloy.Supported by Research Fund of Science and Technology Commission of Shanghai Municipality(Grant No.08DZ2271100) and Shanghai Leading Academic Discipline Project (Grant No. S30206).

  15. Coating of titanium implants with boron nitride by RF-magnetron sputtering

    Indian Academy of Sciences (India)

    CEREN GÖKMENOGLU; NURDAN ÖZMERIÇ; GAYE ÇAKAL; NIHAN DÖKMETAS; CANSU ERGENE; BILGIN KAFTANOGLU

    2016-09-01

    Surface modification is necessary for titanium implants since it is unable to induce bone apposition. The beneficial effects of boron on bone formation, composition and physical properties make it suitable as a coating material. In the present study, surface properties of boron nitride (BN) coating on titanium implants were evaluated. Twenty-four implants and 12 abutments were coated with BN by RF-magnetron sputtering system. ATR–FTIR measurements were conducted to assess surface chemistry and morphology of BN-coated implants. Adhesion tests were performed by CSM nanoscratch test device to determine adhesion of BN to titanium surface. Surface profilometry and atomic force microscopy (AFM) was used to evaluate surface roughness.Mean roughness values were calculated. Contact angle measurements were done for evaluation of wettability. Surface characterization of coated implants was repeated after RF power of the system was increased and voltage values were changed to evaluate if these settings have an impact on coating quality. Three different voltage values were used for this purpose. Hexagonal-BN was determined in FTIR spectra. RF-coating technique provided adequate adherence of BN coatings to the titanium surface. A uniform BN coating layer was formed on the titanium implants with no deformation on the titanium surface. Similar roughness values were maintained after BN coating procedure. Before coating, the contact angles of the implants were in between 63$^{\\circ}$ and 79$^{\\circ}$, whereas BN coated implants’ contact angles ranged between 46$^{\\circ}$ and 67$^{\\circ}$. BN-coated implant surfaces still have hydrophilic characteristics. The change in voltage values seemed to affect the surface coating characteristics. Especially, the phase of the BN coating was different when different voltages were used. According to our results, BN coating can be sufficiently performed on pretreated implant surfaces and the characteristicsof BN coated surfaces can be

  16. Clad modified optical fiber gas sensors based on nanocrystalline nickel oxide embedded coatings

    Science.gov (United States)

    Yamini, K.; Renganathan, B.; Ganesan, A. R.; Prakash, T.

    2017-07-01

    A clad modified optical fiber gas sensor for sensing volatile organic compound vapours (VOCs) such as formaldehyde (HCHO), ammonia (NH3), ethanol (C2H5OH) and methanol (CH3OH) up to 500 ppm was studied using nanocrystalline nickel oxide embedded coatings. Prior to the measurements, nickel oxide in two different crystallite sizes such as 24 nm and 76 nm was synthesized by calcination of reverse precipitated nickel hydroxide subsequently at 450 °C and 900 °C for 30 min. Then, samples physical properties were characterized using X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). Our gas sensing measurement concludes that the lower crystallite size (24 nm) nickel oxide nanocrystals exhibits superior performance to formaldehyde and ethanol vapours as compared with other two VOCs, the observed experimental results were discussed in detail.

  17. Nanocrystalline Diamond as a Coating for Joint Implants: Cytotoxicity and Biocompatibility Assessment

    Directory of Open Access Journals (Sweden)

    Margarida Amaral

    2008-01-01

    Full Text Available Nanocrystalline diamond (NCD coatings combine a very low surface roughness with the outstanding diamond properties, such as superlative hardness, low self-friction coefficient, high wear and corrosion resistance, and biotolerance, which are ideal features for applications in medicine (knee and hip replacement and surgical tools. The present work presents a comprehensive study of the cytotoxicity and biocompatibility of NCD films grown by hot-filament chemical vapour deposition (HFCVD technique, aiming such future applications. Cytotoxicity was evaluated in vitro by seeding human gingival fibroblasts on the NCD surface for 14 days, while specific biocompatibility was assessed on samples seeded with human bone marrow-derived osteoblasts during 21 days. The NCD coatings proved to be noncytotoxic in the preliminary human gingival fibroblast cell cultures, as denoted by a notable sequence of cell attachment, spreading, and proliferation events. In the specific biocompatibility assay envisaging bone tissue applications, NCD coatings induced human osteoblast proliferation and the stimulation of differentiation markers, compared to standard polystyrene tissue culture plates.

  18. The Formation of Nanocrystalline Diamond Coating on WC Deposited by Microwave Assisted Plasma CVD

    Science.gov (United States)

    Toff, M. R. M.; Hamzah, E.; Purniawan, A.

    2010-03-01

    Diamond is one form of carbon structure. The extreme hardness and high chemical resistant of diamond coatings determined that many works on this area relate to coated materials for tribological applications in biomedicine, as mechanical seals or cutting tools for hard machining operations. In the work, nanocrystalline diamond (NCD) coated tungsten carbide (WC) have been deposited by microwave assisted plasma chemical vapor deposition (MAPCVD) from CH4/H2 mixtures. Morphology of NCD was investigated by using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The quality of NCD is defined as ratio between diamond and non diamond and also full width at half maximum (FWHM) was determined using Raman spectra. The result found that the NCD structure can be deposited on WC surface using CH4/H2 gas mixture with grain size ˜20 nm to 100 nm. Increase %CH4 concentration due to increase the nucleation of NCD whereas decrease the quality of diamond. Based on Raman spectra, the quality of NCD is in the range ˜98.82-99.01% and 99.56-99.75% for NCD and microcrystalline (MCD), respectively. In addition, FWHM of NCD is high than MCD in the range of 8.664-62.24 cm-1 and 4.24-5.05 cm-1 for NCD and MCD respectively that indicate the crystallineity of NCD is smaller than MCD.

  19. Effect of Plasma Nitriding and Nitrocarburizing on HVOF-Sprayed Stainless Steel Coatings

    Science.gov (United States)

    Park, Gayoung; Bae, Gyuyeol; Moon, Kyungil; Lee, Changhee

    2013-12-01

    In this work, the effects of plasma nitriding (PN) and nitrocarburizing on HVOF-sprayed stainless steel nitride layers were investigated. 316 (austenitic), 17-4PH (precipitation hardening), and 410 (martensitic) stainless steels were plasma-nitrided and nitrocarburized using a N2 + H2 gas mixture and the gas mixture containing C2H2, respectively, at 550 °C. The results showed that the PN and nitrocarburizing produced a relatively thick nitrided layer consisting of a compound layer and an adjacent nitrogen diffusion layer depending on the crystal structures of the HVOF-sprayed stainless steel coatings. Also, the diffusion depth of nitrogen increased when a small amount of C2H2 (plasma nitrocarburizing process) was added. The PN and nitrocarburizing resulted in not only an increase of the surface hardness, but also improvement of the load bearing capacity of the HVOF-sprayed stainless steel coatings because of the formation of CrN, Fe3N, and Fe4N phases. Also, the plasma-nitrocarburized HVOF-sprayed 410 stainless steel had a superior surface microhardness and load bearing capacity due to the formation of Cr23C6 on the surface.

  20. Effect of plasma nitriding on electrodeposited Ni–Al composite coating

    DEFF Research Database (Denmark)

    Daemi, N.; Mahboubi, F.; Alimadadi, Hossein

    2011-01-01

    In this study plasma nitriding is applied on nickel–aluminum composite coating, deposited on steel substrate. Ni–Al composite layers were fabricated by electro-deposition process in Watt’s bath containing Al particles. Electrodeposited specimens were subjected to plasma atmosphere comprising of N2......–20% H2, at 500°C, for 5h. The surface morphology investigated, using a scanning electron microscope (SEM) and the surface roughness was measured by use of contact method. Chemical composition was analyzed by X-ray fluorescence spectroscopy and formation of AlN phase was confirmed by X-ray diffraction....... The corrosion resistance of composite coatings was measured by potentiodynamic polarization in 3.5% NaCl solution. The obtained results show that plasma nitriding process leads to an increase in microhardness and corrosion resistance, simultaneously....

  1. Influence of pH on ZnO nanocrystalline thin films prepared by sol–gel dip coating method

    Indian Academy of Sciences (India)

    K Sivakumar; V Senthil Kumar; N Muthukumarasamy; M Thambidurai; T S Senthil

    2012-06-01

    ZnO nanocrystalline thin films have been prepared on glass substrates by sol–gel dip coating method. ZnO thin films have been coated at room temperature and at four different pH values of 4, 6, 8 and 10. The X-ray diffraction pattern showed that ZnO nanocrystalline thin films are of hexagonal structure and the grain size was found to be in the range of 25–45 nm. Scanning electron microscopic images show that the surface morphology improves with increase of pH values. TEM analysis reveals formation of ZnO nanocrystalline with an average grain size of 44 nm. The compositional analysis results show that Zn and O are present in the sample. Optical band studies show that the films are highly transparent and exhibit a direct bandgap. The bandgap has been found to lie in the range of 3.14–3.32 eV depending on pH suggesting the formation of ZnO nanocrystalline thin films.

  2. The adhesion solidity, physico-mechanical and tribological properties of the coating of titanium nitride

    Science.gov (United States)

    Krivina, L. A.; Tarasenko, Yu P.; Fel, Ya A.

    2017-05-01

    Influence of variable technological factors (arch current, fractional pressure of gas in the camera) on structure, physic-mechanical and tribological features of an ion-plasma coating of titanium nitride has been investigated. The adhesion solidity has been put to the test and the mechanism of destruction of a covering has been also researched by a skretch-test method. The optimal mode of spraying at which the formation of the nanostructured bar coating of TiN has been defined. The covering offers an optimal combination of physic-mechanical, tribological and solidity features.

  3. Generation of low-temperature plasma by low-pressure arcs for synthesis of nitride coatings

    Science.gov (United States)

    Krysina, O. V.; Koval, N. N.; Lopatin, I. V.; Shugurov, V. V.; Kovalsky, S. S.

    2016-01-01

    Experiments were performed to study gas, metal, and mixed metal-gas plasmas. The plasmas were generated with the use of an arc evaporator and a gas-plasma source with a hot filament and hollow cathode that were operated independently or simultaneously. It has been revealed that the arc current of gas-plasma source affects the parameters of the metal-gas plasma and the element concentrations in the coatings. It has been demonstrated that the characteristics of the nitride coatings produced by plasma-assisted vacuum-arc deposition can be controlled by varying the parameters of the arc in the gas-plasma source.

  4. Preparation and characterization of boron nitride coatings on carbon fibers from borazine by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Li Junsheng, E-mail: charlesljs@163.com [State Key Laboratory of Advanced Ceramic Fibers and Composites, College of Aerospace and Materials Engineering, National University of Defense Technology, Changsha, 410073 (China); Zhang Changrui; Li Bin [State Key Laboratory of Advanced Ceramic Fibers and Composites, College of Aerospace and Materials Engineering, National University of Defense Technology, Changsha, 410073 (China)

    2011-06-15

    Boron nitride (BN) coatings were deposited on carbon fibers by chemical vapor deposition (CVD) using borazine as single source precursor. The deposited coatings were characterized by scanning electron microscopy (SEM), Auger electron spectroscopy (AES), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The effect of temperatures on growth kinetics, morphology, composition and structure of the coatings was investigated. In the low temperature range of 900 deg. C-1000 deg. C, the growth rate increased with increasing temperature complying with Arrhenius law, and an apparent active energy of 72 kJ/mol was calculated. The coating surface was smooth and compact, and the coatings uniformly deposited on individual fibers of carbon fiber bundles. The growth was controlled by surface reaction. At 1000 deg. C, the deposition rate reached a maximum (2.5 {mu}m/h). At the same time, the limiting step of the growth translated to be mass-transportation. Above 1100 deg. C, the growth rate decreased drastically due to the occurrence of gas-phase nucleation. Moreover, the coating surface became loose and rough. Composition and structure examinations revealed that stoichiometric BN coatings with turbostratic structure were obtained below 1000 deg. C, while hexagonal BN coatings were deposited above 1100 deg. C. A penetration of carbon element from the fibers to the coatings was observed.

  5. Adhesion enhancement of titanium nitride coating on aluminum casting alloy by intrinsic microstructures

    Science.gov (United States)

    Nguyen, Chuong L.; Preston, Andrew; Tran, Anh T. T.; Dickinson, Michelle; Metson, James B.

    2016-07-01

    Aluminum casting alloys have excellent castability, high strength and good corrosion resistance. However, the presence of silicon in these alloys prevents surface finishing with conventional methods such as anodizing. Hard coating with titanium nitride can provide wear and corrosion resistances, as well as the aesthetic finish. A critical factor for a durable hard coating is its bonding with the underlying substrate. In this study, a titanium nitride layer was coated on LM25 casting alloy and a reference high purity aluminum substrate using Ion Assisted Deposition. Characterization of the coating and the critical interface was carried out by a range of complementing techniques, including SIMS, XPS, TEM, SEM/EDS and nano-indentation. It was observed that the coating on the aluminum alloy is stronger compared to that on the pure aluminum counterpart. Silicon particles in the alloy offers the reinforcement though mechanical interlocking at microscopic level, even with nano-scale height difference. This reinforcement overcomes the adverse effect caused by surface segregation of magnesium in aluminum casting alloys.

  6. Investigation of hexagonal boron nitride as an atomically thin corrosion passivation coating in aqueous solution

    Science.gov (United States)

    Zhang, Jing; Yang, Yingchao; Lou, Jun

    2016-09-01

    Hexagonal boron nitride (h-BN) atomic layers were utilized as a passivation coating in this study. A large-area continuous h-BN thin film was grown on nickel foil using a chemical vapor deposition method and then transferred onto sputtered copper as a corrosion passivation coating. The corrosion passivation performance in a Na2SO4 solution of bare and coated copper was investigated by electrochemical methods including cyclic voltammetry (CV), Tafel polarization and electrochemical impedance spectroscopy (EIS). CV and Tafel analysis indicate that the h-BN coating could effectively suppress the anodic dissolution of copper. The EIS fitting result suggests that defects are the dominant leakage source on h-BN films, and improved anti-corrosion performances could be achieved by further passivating these defects.

  7. Ni-WC composite coatings by carburizing electrodeposited amorphous and nanocrystalline Ni-W alloys

    Science.gov (United States)

    Latif, Saadia; Mehmood, Mazhar; Ahmad, Jamil; Aslam, Muhammad; Ahmed, Maqsood; Zhang, Zhi-dong

    2010-03-01

    In situ formation of tungsten carbide in the matrix of FCC nickel has been achieved by carburizing of the electrodeposited Ni-W alloy coatings. The size of the carbide particles ranges between 100 and 500 nm. The carbide phase is also present in the form of very small precipitates inside the nickel grains. The size of such precipitates is between 10 and 40 nm. The carburizing environment was created by introducing a flowing mixture of vaporized 95.5% alcohol (0.25 ml/min, liquid) and argon (0.5 L/min, gas) into the carburizing furnace. Supersaturated nature of electrodeposited amorphous and nanocrystalline alloys, in addition to high diffusivity, have been attributed for the formation of carbide phase in the deposits at a temperature range of 700-850 °C. The carbide-metal interface is clean and the composite coatings are compact. Hardness values up to about 1100 KHN are achieved. Hardness increases with tungsten content and carburizing temperature.

  8. Ni-WC composite coatings by carburizing electrodeposited amorphous and nanocrystalline Ni-W alloys

    Energy Technology Data Exchange (ETDEWEB)

    Latif, Saadia [National Centre for Nanotechnology, Department of Chemical and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad 45650 (Pakistan); Mehmood, Mazhar, E-mail: mazhar@pieas.edu.pk [National Centre for Nanotechnology, Department of Chemical and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad 45650 (Pakistan); Ahmad, Jamil; Aslam, Muhammad [National Centre for Nanotechnology, Department of Chemical and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad 45650 (Pakistan); Ahmed, Maqsood [Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan); Zhang Zhidong [Institute of Metals Research, Chinese Academy of Science, Shenyang (China)

    2010-03-01

    In situ formation of tungsten carbide in the matrix of FCC nickel has been achieved by carburizing of the electrodeposited Ni-W alloy coatings. The size of the carbide particles ranges between 100 and 500 nm. The carbide phase is also present in the form of very small precipitates inside the nickel grains. The size of such precipitates is between 10 and 40 nm. The carburizing environment was created by introducing a flowing mixture of vaporized 95.5% alcohol (0.25 ml/min, liquid) and argon (0.5 L/min, gas) into the carburizing furnace. Supersaturated nature of electrodeposited amorphous and nanocrystalline alloys, in addition to high diffusivity, have been attributed for the formation of carbide phase in the deposits at a temperature range of 700-850 deg. C. The carbide-metal interface is clean and the composite coatings are compact. Hardness values up to about 1100 KHN are achieved. Hardness increases with tungsten content and carburizing temperature.

  9. Antimicrobial activity of nanocomposite zirconium nitride/silver coatings to combat external bone fixation pin infections.

    Science.gov (United States)

    Wickens, David J; West, Glen; Kelly, Peter J; Verran, Joanna; Lynch, Stephen; Whitehead, Kathryn A

    2012-10-01

    During external fixation, temporary implants are used to penetrate the skin, muscle and bone to support severely fractured bones. This creates a biologically critical interface at the site of entry, which potentially allows a risk of infection. The aim of this study, therefore, was to investigate potential antimicrobial nanocomposites to combat infection. Magnetron sputtering was used to produce zirconium nitride/silver nanocomposite coatings, which were prepared at two different silver concentrations of 15.5 at.% and 29.8 at.%. These coatings were characterized for morphology, chemical composition, and antimicrobial activity in comparison to pure zirconium nitride and stainless steel. Staphylococcus aureus and Staphylococcus epidermidis were used as in vitro test organisms in a range of antimicrobial assays; retention of the bacteria on the surfaces and their survival using LiveDead™ staining; the use of a metabolic redox dye to indicate a contact kill and zone of inhibition assays to indicate leaching of inhibitory silver ions. Antimicrobial tests demonstrated a significant kill when the bacterial cells came in contact with the coatings containing silver at both 15.5 at.% and 29.8 at.%. No inhibitory leaching from the surfaces occurred. These surfaces demonstrate potential for use as antimicrobial fixation pin coatings.

  10. Modification of the structure and properties of gradient nanocrystalline coatings Ti-Al-Si-Cu-N by annealing in vacuum

    Science.gov (United States)

    Ovchinnikov, Stanislav; Pinzhin, Yurii

    2016-11-01

    The nanocrystalline gradient coatings system Ti-Al-Si-Cu-N were annealed in the temperature range of 500- 1100°C. Their composition, structure, and mechanical properties were studied by methods of scanning and transmission electron microscopy, scratch test, and measurement of nanohardness. It is shown that the diffusion of substrate elements has a crucial impact on the heat-activated processes of structure recovery, the growth of crystal size and the properties of materials. This results in nanocomposite structure with high adhesion characteristics of the coatings.

  11. Nanocrystalline ceria coatings on solid oxide fuel cell anodes: the role of organic surfactant pretreatments on coating microstructures and sulfur tolerance

    Directory of Open Access Journals (Sweden)

    Chieh-Chun Wu

    2014-10-01

    Full Text Available Treatments with organic surfactants, followed by the deposition of nanocrystalline ceria coatings from aqueous solution, were applied to anodes of solid oxide fuel cells. The cells were then operated in hydrogen/nitrogen fuel streams with H2S contents ranging from 0 to 500 ppm. Two surfactant treatments were studied: immersion in dodecanethiol, and a multi-step conversion of a siloxy-anchored alkyl bromide to a sulfonate functionality. The ceria coatings deposited after the thiol pretreatment, and on anodes with no pretreatment, were continuous and uniform, with thicknesses of 60–170 nm and 100–140 nm, respectively, and those cells exhibited better lifetime performance and sulfur tolerance compared to cells with untreated anodes and anodes with ceria coatings deposited after the sulfonate pretreatment. Possible explanations for the effects of the treatments on the structure of the coatings, and for the effects of the coatings on the performance of the cells, are discussed.

  12. Nanocrystalline ceria coatings on solid oxide fuel cell anodes: the role of organic surfactant pretreatments on coating microstructures and sulfur tolerance.

    Science.gov (United States)

    Wu, Chieh-Chun; Tang, Ling; De Guire, Mark R

    2014-01-01

    Treatments with organic surfactants, followed by the deposition of nanocrystalline ceria coatings from aqueous solution, were applied to anodes of solid oxide fuel cells. The cells were then operated in hydrogen/nitrogen fuel streams with H2S contents ranging from 0 to 500 ppm. Two surfactant treatments were studied: immersion in dodecanethiol, and a multi-step conversion of a siloxy-anchored alkyl bromide to a sulfonate functionality. The ceria coatings deposited after the thiol pretreatment, and on anodes with no pretreatment, were continuous and uniform, with thicknesses of 60-170 nm and 100-140 nm, respectively, and those cells exhibited better lifetime performance and sulfur tolerance compared to cells with untreated anodes and anodes with ceria coatings deposited after the sulfonate pretreatment. Possible explanations for the effects of the treatments on the structure of the coatings, and for the effects of the coatings on the performance of the cells, are discussed.

  13. Nanocrystalline ceria coatings on solid oxide fuel cell anodes: the role of organic surfactant pretreatments on coating microstructures and sulfur tolerance

    Science.gov (United States)

    Wu, Chieh-Chun; Tang, Ling

    2014-01-01

    Summary Treatments with organic surfactants, followed by the deposition of nanocrystalline ceria coatings from aqueous solution, were applied to anodes of solid oxide fuel cells. The cells were then operated in hydrogen/nitrogen fuel streams with H2S contents ranging from 0 to 500 ppm. Two surfactant treatments were studied: immersion in dodecanethiol, and a multi-step conversion of a siloxy-anchored alkyl bromide to a sulfonate functionality. The ceria coatings deposited after the thiol pretreatment, and on anodes with no pretreatment, were continuous and uniform, with thicknesses of 60–170 nm and 100–140 nm, respectively, and those cells exhibited better lifetime performance and sulfur tolerance compared to cells with untreated anodes and anodes with ceria coatings deposited after the sulfonate pretreatment. Possible explanations for the effects of the treatments on the structure of the coatings, and for the effects of the coatings on the performance of the cells, are discussed. PMID:25383282

  14. Determination of elastic and thermal properties of a thin nanocrystalline diamond coating using all-optical methods

    Energy Technology Data Exchange (ETDEWEB)

    Sermeus, J.; Verstraeten, B.; Salenbien, R. [KU Leuven-University of Leuven, Soft Matter and Biophysics, Celestijnenlaan 200D, B-3001 Heverlee (Belgium); Pobedinskas, P.; Haenen, K. [Instituut voor Materiaalonderzoek (IMO), Hasselt University, Wetenschapspark 1, 3590 Diepenbeek (Belgium); IMOMEC, IMEC vzw, Wetenschapspark 1, 3590 Diepenbeek (Belgium); Glorieux, C., E-mail: christ.glorieux@fys.kuleuven.be [KU Leuven-University of Leuven, Soft Matter and Biophysics, Celestijnenlaan 200D, B-3001 Heverlee (Belgium)

    2015-09-01

    Results are presented on the thermal and elastic properties of a thin, 1.5 μm, nanocrystalline diamond coating (NCD), deposited on a silicon substrate by microwave plasma enhanced chemical vapor deposition. A combination of two all-optical measurement techniques, impulsive stimulated thermal scattering and grating induced laser beam deflection, was employed to launch and detect surface acoustic waves (SAWs). The relation between the dispersive propagation velocity of SAWs to the coating-substrate geometry is exploited to determine the elastic properties of the NCD coating. The elastic properties are found to be consistent with literature values. The thermal properties of the coating were determined by monitoring the thermal diffusion induced washing away of the laser induced transient surface temperature grating. The transient thermal grating signals were fitted by the low-frequency limit of a thermoelastic model for a multilayer configuration. Similar to the dispersion of the surface acoustic wave velocity, the characteristic time of the thermal diffusion driven grating decay evolves from a coating-dominated value at short grating spacings towards a substrate-dominated value at grating spacings well exceeding the coating thickness. The grating spacing dependence of the corresponding effective thermal diffusivity was experimentally determined and fitted, leading to a value for the thermal diffusivity of the NCD coating α{sub NCD} = 8.4{sub −0.1}{sup +2.7} mm{sup 2}·s{sup −1}, which is an order of magnitude lower than that of the silicon substrate. The low value of the thermal diffusivity is interpreted with a simple touching model. - Highlights: • We investigate a thin nano-crystalline diamond coating. • We used two all optical surface acoustic wave based methods. • We found a young's modulus and density that is in line with literature. • The thermal diffusivity of the NCD coating was 2 orders of magnitude lower than the one of bulk diamond.

  15. Nanocrystalline particle coatings on alpha-alumina powders by a carbonate precipitation and thermal-assisted combustion route.

    Science.gov (United States)

    Kim, Sang Woo; Jung, Young Mi

    2007-11-01

    We have suggested ultrafine particle coating processes for preparing nanocrystalline particle coated alpha-alumina powders by a carbonate precipitation and thermal-assisted combustion route, which is environmentally friendly. The nanometric ammonium aluminum carbonate hydroxide (AACH) as a precursor for coating of alumina was produced from precipitation reaction of ammonium aluminum sulfate and ammonium hydrogen carbonate. The synthetic crystalline size and morphology were greatly dependent on pH and temperature. By adding ammonium aluminum sulfate solution dispersed the alpha-alumina core particle in the ammonium hydrogen carbonate aqueous solution, nanometric AACH with a size of 5 nm was tightly bonded and uniformly coated on the core powder due to formation of surface complexes by the adsorption of carbonates, hydroxyl and ammonia groups on the surface of aluminum oxide. The synthetic precursor rapidly converted to amorphous- and y-alumina phase without significant change in the morphological features through decomposition of surface complexes and thermal-assisted phase transformation. As a result, the nanocrystalline polymorphic particle coated alpha-alumina core powders with highly uniform distribution were prepared from the route of carbonate precipitation and thermal-assisted combustion.

  16. 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.

  17. Boron Nitride Coated Carbon Nanotube Arrays with Enhanced Compressive Mechanical Property

    Science.gov (United States)

    Jing, Lin; Tay, Roland Yingjie; Li, Hongling; Tsang, Siu Hon; Tan, Dunlin; Zhang, Bowei; Tok, Alfred Iing Yoong; Teo, Edwin Hang Tong

    Vertically aligned carbon nanotube (CNT) array is one of the most promising energy dissipating materials due to its excellent temperature invariant mechanical property. However, the CNT arrays with desirable recoverability after compression is still a challenge. Here, we report on the mechanical enhancement of the CNT arrays reinforced by coating with boron nitride (BN) layers. These BN coated CNT (BN/CNT) arrays exhibit excellent compressive strength and recoverability as compared to those of the as-prepared CNT arrays which totally collapsed after compression. In addition, the BN coating also provides better resistance to oxidation due to its intrinsic thermal stability. This work presented here opens a new pathway towards tuning mechanical behavior of any arbitrary CNT arrays for promising potential such as damper, vibration isolator and shock absorber applications.

  18. Reactive Plasma-Sprayed Aluminum Nitride-Based Coating Thermal Conductivity

    Science.gov (United States)

    Shahien, Mohammed; Yamada, Motohiro; Fukumoto, Masahiro; Egota, Kazumi; Okamoto, Kenji

    2015-12-01

    Recently, thick aluminum nitride/alumina (AlN/Al2O3) composite coatings were successfully fabricated through the reactive plasma spraying of fine Al2O3/AlN mixture in the N2/H2 atmospheric plasma. The coatings consist of AlN, Al5O6N, γ-Al2O3, and α-Al2O3 phases. This study will evaluate the thermal conductivity of these complicated plasma-sprayed coatings and optimize the controlling aspects. Furthermore, the influence of the process parameters on the coatings thermal conductivity will be investigated. The fabricated coatings showed very low thermal conductivity (2.43 W/m K) compared to the AlN sintered compacts. It is attributed to the phase composition of the fabricated coatings, oxide content, and porosity. The presence of Al2O3, Al5O6N and the high coating porosity decreased its thermal conductivity. The presence of oxygen in the AlN lattice creates Al vacancies which lead to phonon scattering and therefore suppressed the thermal conductivity. The formation of γ-Al2O3 phase in the coating leads to further decrease in its conductivity, due to its lower density compared to the α-phase. Moreover, the high porosity of the coating strongly suppressed the conductivity. This is due to the complicated microstructure of plasma spray coatings (splats, porosity, and interfaces, particularly in case of reactive spray process), which obviously lowered the conductivity. Furthermore, the measured coating density was lower than the AlN value and suppressed the coating conductivity. In addition, the spraying parameter showed a varied effect on the coating phase composition, porosity, density, and therefore on its conductivity. Although the N2 gas flow improved the nitride content, it suppressed the thermal conductivity gradually. It is attributed to the further increase in the porosity and further decrease in the density of the coatings with the N2 gas. Furthermore, increasing the arc did not show a significant change on the coating thermal conductivity. On the other hand

  19. Structural characterization of supported nanocrystalline ZnO thin films prepared by dip-coating

    Energy Technology Data Exchange (ETDEWEB)

    Casanova, J.R. [CITEDEF-CINSO-CONICET Centro de Investigaciones en Solidos, Juan B. de La Salle 4397, B1603ALO, Villa Martelli, Buenos Aires (Argentina); Heredia, E.A., E-mail: eheredia@citedef.gob.ar [CITEDEF-CINSO-CONICET Centro de Investigaciones en Solidos, Juan B. de La Salle 4397, B1603ALO, Villa Martelli, Buenos Aires (Argentina); Bojorge, C.D.; Canepa, H.R. [CITEDEF-CINSO-CONICET Centro de Investigaciones en Solidos, Juan B. de La Salle 4397, B1603ALO, Villa Martelli, Buenos Aires (Argentina); Kellermann, G. [Departamento de Fisica, Universidade Federal do Parana, Curitiba, PR (Brazil); Craievich, A.F. [Instituto de Fisica, Universidade de Sao Paulo, Cidade Universitaria, Sao Paulo, SP (Brazil)

    2011-09-15

    Nanocrystalline ZnO thin films prepared by the sol-gel dip-coating technique were characterized by grazing incidence X-ray diffraction (GIXD), atomic force microscopy (AFM), X-ray reflectivity (XR) and grazing incidence small-angle X-ray scattering (GISAXS). The structures of several thin films subjected to (i) isochronous annealing at 350, 450 and 550 deg. C, and (ii) isothermal annealing at 450 deg. C during different time periods, were characterized. The studied thin films are composed of ZnO nanocrystals as revealed by analysing several GIXD patterns, from which their average sizes were determined. Thin film thickness and roughness were determined from quantitative analyses of AFM images and XR patterns. The analysis of XR patterns also yielded the average density of the studied films. Our GISAXS study indicates that the studied ZnO thin films contain nanopores with an ellipsoidal shape, and flattened along the direction normal to the substrate surface. The thin film annealed at the highest temperature, T = 550 deg. C, exhibits higher density and lower thickness and nanoporosity volume fraction, than those annealed at 350 and 450 deg. C. These results indicate that thermal annealing at the highest temperature (550 deg. C) induces a noticeable compaction effect on the structure of the studied thin films.

  20. Dip coated nanocrystalline CdZnS thin films for solar cell application

    Energy Technology Data Exchange (ETDEWEB)

    Dongre, J. K., E-mail: jk-dongre@yahoo.com; Chaturvedi, Mahim; Patil, Yuvraj; Sharma, Sandhya; Jain, U. K. [Government Autonomous Post Graduate College Chhindwara, 480001 (India)

    2015-07-31

    Nanocrystalline cadmium sulfide (CdS) and zinc cadmium sulfide (ZnCdS) thin films have been grown via simple and low cost dip coating technique. The prepared films are characterized by X-ray diffraction (XRD), atomic force microscopic (AFM) and UV-VIS spectrophotometer techniques to reveal their structural, morphological and optical properties. XRD shows that both samples grown have zinc blende structure. The grain size is calculated as 6.2 and 8 nm using Scherrer’s formula. The band gap value of CdS and CdZnS film is estimated to be 2.58 and 2.69 eV respectively by UV-vis spectroscopy. Photoelectrochemical (PEC) investigations are carried out using cell configuration as n-CdZnS/(1M NaOH + 1M Na2S + 1M S)/C. The photovoltaic output characteristic is used to calculate fill-factor (FF) and solar conversion efficiency (η)

  1. Microstructural behavior of nitriding compound layer for Nb-carbonitride coating grown by thermo-reactive diffusion process

    Science.gov (United States)

    Lee, Kyunghoon; Kang, Namhyun; Bae, Jong-Seong; Lee, Chang-Woo

    2016-09-01

    This study aims to understand the microstructural behavior of nitriding compound layer and its effect on Nb-carbonitride growth produced by the thermo-reactive diffusion (TRD) process. Gas nitriding was performed at 550 °C for 3 and 6 h, followed by TRD at 900 °C for 6 h. The nitriding compound layers had thicknesses of 10 and 16 μm for nitriding time of 3 and 6 h, respectively. The corresponding Nb-carbonitride layers produced by TRD were 7.2 and 11.2 μm thick, respectively. Reheating at 900 °C transformed the microstructure of the nitriding compounds to Fe3O4 and FeN0.0939. As reheating proceeded to 30 min, high concentration of nitrogen, initially existing in the nitride layer diffused to 80-90 μm into the substrate. Therefore, the TRD process produced NbN layer at the interfacial area due to intensively dissolved nitrogen from FeN0.0939. As the TRD proceeded, supply of C atoms from the base metal became competitive with the N diffusion. Thus, the TRD coating layer was grown to above the interface. Reheating at 900 °C for the 16-μm-thick nitride layer resulted in a nitrogen content ˜0.4 at% higher than that for the 10-μm-thick nitride layer, thereby producing a thicker Nb-carbonitride layer.

  2. Functionalized hexagonal boron nitride nano-coatings for protection of transparent plastics

    Science.gov (United States)

    Van Tran, Thu; Usta, Aybala; Asmatulu, Ramazan

    2016-04-01

    Nanocoating is the result of a coating application of nanomaterials to build a consistent network of molecules in a paint to protect the surfaces of various materials and devices. Hexagonal Boron Nitride (h-BN) is in two dimensional form with excellent thermal, mechanical and chemical properties. These BN nanocoatings are also a thermally insulating material for heat management. After adding functionalized h-BNs into paints or other coatings, they will absorb the harmful UV part of sunlight and prevent coating against the environmental degradations. The impacts of the environmental factors on the coatings can be substantially eliminated. In the present study, h-BNs were modified with [2-(2-Aminoethylamino) propyl] trimethoxysilane and uniformly dispersed into the polyurethane coatings with different amounts, such as 0.1, 0.2, 0.4, and 0.8wt% to increase hardness and water resistance, and decrease the UV degradation level of coatings and transparent plastics. The prepared samples were characterized by using Fourier Transform Infrared Spectroscopy (FTIR), UV-Vis Spectroscopy, Scanning Electron Microscope (SEM), Water Contact Angle, and Differential Scanning Calorimeter (DSC). The test results showed that the nanocoatings with functionalized h-BN provided excellent physical and chemical behaviors against the UV and other physical degradations on the substrates.

  3. Oxidation and corrosion behavior of titanium aluminum nitride coatings by arc ion plating

    Institute of Scientific and Technical Information of China (English)

    LI Ming-sheng; FENG Chang-jie; ZHANG Zhi-feng; WANG Fu-hui

    2006-01-01

    Composite metastable TiN and Ti1-xAlxN coatings with different Al content were deposited on 1Cr11Ni2W2MoV stainless steel for aero-engine compressor blades by arc ion plating. The results show that all coatings have a B1NaCl structure and the preferred orientation changes from (111) to (220) with increasing Al content; the lattice parameter of Ti1-xAlxN decreases with the increase of Al content. The oxidation-resistance of (Ti,Al)N coatings is significantly improved owing to the formation of Al-riched oxide on the surface of the coatings. The nitride coatings can significantly improve the corrosion-resistance of 1Cr11Ni2W2MoV stainless steel under the synergistic of water vapor and NaCl, and the corrosion-resistance becomes better when the Al content increases, because not only the quick formation of thin alumina layer prevents the further corrosion but also the formation of alumina seals the pinholes or defects in the coatings, which prevents the occurrence of localized nodules-like corrosion.

  4. Static tensile and tensile creep testing of four boron nitride coated ceramic fibers at elevated temperatures

    Science.gov (United States)

    Coguill, Scott L.; Adams, Donald F.; Zimmerman, Richard S.

    1989-01-01

    Six types of uncoated ceramic fibers were static tensile and tensile creep tested at various elevated temperatures. Three types of boron nitride coated fibers were also tested. Room temperature static tensile tests were initially performed on all fibers, at gage lengths of 1, 2, and 4 inches, to determine the magnitude of end effects from the gripping system used. Tests at one elevated temperature, at gage lengths of 8 and 10 inches, were also conducted, to determine end effects at elevated temperatures. Fiber cross sectional shapes and areas were determined using scanning electron microscopy. Creep testing was typically performed for 4 hours, in an air atmosphere.

  5. EXPERIMENTAL STUDY ON SUPERFICIAL COAT OF GEARS OF NITRIDED 32Cr2MoV COATED WITH TiN FILM BY MULTI-ARC ION PLATING

    Institute of Scientific and Technical Information of China (English)

    LI Hui; LI Runfang; XU Hongbin; ZHANG Jin

    2007-01-01

    After 32CrMoV is selected to manufacture nitrided gears coated with TiN by multi-arc ion plating, all of these uncoated gears and coated gears run in the gearbox under the same initial conditions so as to compare their difference concerning properties and microstructure. Experiment results indicate that tooth surface of the coated-TiN gears does not suffer surface abnormalities in meshed zone. Instead, the gears with nitrided case exhibit an abrasion mark on the meshed zone of tooth surface, which results in more weight loss of nitrided gears. The morphology of the surface suggests TiN film with more than 2000 HV is so dense and smooth that coated-TiN gears have higher wear resistance compared with the uncoated gears. The microstructure of coated-TiN gears is finer, hardness is higher and its distribution of coated-TiN gears is more reliable than uncoated ones, which makes nitride layer combined with TiN film tightly. Consequently, the wear-resistance of gears has been dramatically promoted.

  6. Comparative Study of the PVD Coatings on the Plasma Nitrided Steel

    Directory of Open Access Journals (Sweden)

    Andrei SURZHENKOV

    2012-03-01

    Full Text Available In the current study, the cracking, impact and sliding wear resistance of the PVD single layer TiN (I generation, multilayer (Ti,AlN-ML (II generation, gradient (Al,TiN-G and multilayer nanocomposite FiVIc® (both – III generation coatings on the nitrided low alloy steel 42CrMo4 are analysed. The cyclic indentation test (normal load 50 N, 10 000 cycles was carried out to determine the cracking resistance of the coatings. Impact wear test was performed at the normal load 16 N, strokes’ frequency 25 Hz, 104 – 107 strokes. Sliding wear test was applied, using the block-on-plate scheme, Ø 10 mm Al2O3 ball as the counterbody, at the normal load of 10 N, the frequency 5 Hz, the amplitude 10 mm and the test duration 10 min. Best resistance to cracks’ formation is demonstrated by the gradient (Al,TiN-G coating, showing medium radial cracks’ formation, whereas delamination of the coating can be observed in other cases. 1.6 – 1.7 times higher impact wear resistance is shown by the TiN coating in comparison with the other coatings. The FiVIc® coating demonstrates lightly better resistance to sliding wear in comparison with the TiN and (Ti,AlN-ML coatings due to a lower coefficient of friction. The worst sliding wear resistance is observed in the case of the (Al,TiN-G coating due to a high affinity of the coating’s and counterbody’s materials.DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1339

  7. Highly nonlinear sub-micron silicon nitride trench waveguide coated with gold nanoparticles

    Science.gov (United States)

    Huang, Yuewang; Zhao, Qiancheng; Sharac, Nicholas; Ragan, Regina; Boyraz, Ozdal

    2015-05-01

    We demonstrate the fabrication of a highly nonlinear sub-micron silicon nitride trench waveguide coated with gold nanoparticles for plasmonic enhancement. The average enhancement effect is evaluated by measuring the spectral broadening effect caused by self-phase-modulation. The nonlinear refractive index n2 was measured to be 7.0917×10-19 m2/W for a waveguide whose Wopen is 5 μm. Several waveguides at different locations on one wafer were measured in order to take the randomness of the nanoparticle distribution into consideration. The largest enhancement is measured to be as high as 10 times. Fabrication of this waveguide started with a MEMS grade photomask. By using conventional optical lithography, the wide linewidth was transferred to a wafer. Then the wafer was etched anisotropically by potassium hydroxide (KOH) to engrave trapezoidal trenches with an angle of 54.7º. Side wall roughness was mitigated by KOH etching and thermal oxidation that was used to generate a buffer layer for silicon nitride waveguide. The guiding material silicon nitride was then deposited by low pressure chemical vapor deposition. The waveguide was then patterned with a chemical template, with 20 nm gold particles being chemically attached to the functionalized poly(methyl methacrylate) domains. Since the particles attached only to the PMMA domains, they were confined to localized regions, therefore forcing the nanoparticles into clusters of various numbers and geometries. Experiments reveal that the waveguide has negligible nonlinear absorption loss, and its nonlinear refractive index can be greatly enhanced by gold nano clusters. The silicon nitride trench waveguide has large nonlinear refractive index, rendering itself promising for nonlinear applications.

  8. Substrate temperature influence on the trombogenicity in amorphous carbon nitride thin coatings

    Energy Technology Data Exchange (ETDEWEB)

    Galeano-Osorio, D.S.; Vargas, S.; Lopez-Cordoba, L.M.; Ospina, R. [Laboratorio de Fisica del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 via al Magdalena, Manizales (Colombia); Restrepo-Parra, E., E-mail: erestrepopa@unal.edu.co [Laboratorio de Fisica del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 via al Magdalena, Manizales (Colombia); Arango, P.J. [Laboratorio de Fisica del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 via al Magdalena, Manizales (Colombia)

    2010-10-01

    Carbon nitride thin films were obtained through plasma assisted physical vapor deposition technique by pulsed arc, varying the substrate temperature and investigating the influence of this parameter on the films hemocompatibility. For obtaining approaches of blood compatibility, environmental scanning electron microscopy (ESEM) was used in order to study the platelets adherence and their morphology. Moreover, the elemental chemical composition was determined by using energy dispersive spectroscopy (EDS), finding C, N and O. The coatings hemocompatibility was evaluated by in vitro thrombogenicity test, whose results were correlated with the microstructure and roughness of the films obtained. During the films growth process, the substrate temperature was varied, obtaining coatings under different temperatures, room temperature (T{sub room}), 100 deg. C, 150 deg. C and 200 deg. C. Parameters as interelectrodic distance, voltage, work pressure and number of discharges, were remained constant. By EDS, carbon and nitrogen were found in the films. Visible Raman spectroscopy was used, and it revealed an amorphous lattice, with graphitic process as the substrate temperature was increased. However, at a critical temperature of 150 deg. C, this tendency was broken, and the film became more amorphous. This film showed the lowest roughness, 2 {+-} 1 nm. This last characteristic favored the films hemocompatibility. Also, it was demonstrated that the blood compatibility of carbon nitride films obtained were affected by the I{sub D}/I{sub G} or sp{sup 3}/sp{sup 2} ratio and not by the absolute sp{sup 3} or sp{sup 2} concentration.

  9. Adhesion measurements and chemical and microstructural characterization at interfaces of titanium nitride and titanium aluminum nitride coatings on stainless steel, inconel and titanium alloys

    Science.gov (United States)

    James, Robert Dallas

    To assess the adhesion of nitride coatings on metal alloys, Ti 6Al-4V, 17-4 PH stainless steel and Inconel 718 alloy substrates were coated with titanium nitride (TiN) using both cathodic arc and electron beam evaporation. Titanium aluminum nitride ((Ti,Al)N) was also deposited using cathodic arc evaporation. X-ray photoelectron, Auger electron, and energy dispersive x-ray spectroscopies were used in tandem with cross-sectional transmission electron microscopy to analyze the coatings and the coating-substrate interfaces. The interfaces were found to be abrupt with a thin layer of W contamination located between the substrate and the Ti interlayer, deposited to improve adhesion, on electron beam evaporated samples. Metallic macroparticles up to two microns in diameter were observed in cathodic arc evaporated coatings. Residual stress analysis of the coatings revealed the presence of biaxial compressive residual stresses in all coatings. Residual stresses increased for coating-substrate systems with a larger mismatch between the coefficients of thermal expansion for the coating and the substrate. Scratch tests of the coatings revealed lower critical load values for coatings on Ti 6Al-4V due to the lower hardness of the substrate alloy relative to the stainless steel and Inconel alloys. The scratch test is a common method for evaluating adhesion of a coating to its substrate; however, this technique is not well understood due to complex loading of specimen as coating is removed. Plate impact spallation, is a more uncommon method for evaluating adhesion, but the advantage of this technique is that the interface is subjected to purely tensile loading. During plate impact spallation, the interfaces of the coated samples were loaded in tension using a high speed shock wave which caused spallation either at the interface, in the coating or in the metal. Failure in cathodic arc deposited coatings occurred in the form of isolated spallation craters located within the

  10. Structural, Optical and Electrochromic Properties of Nanocrystalline TiO2 Thin Films Prepared by Spin Coating

    OpenAIRE

    2004-01-01

    Nanocrystalline TiO2 thin filmswere prepared by spin coating on covered glass substrates with an indium tin oxide (ITO) layer. The structural, electrochromic and optical properties of the films were investigated. The films are crystallized predominantly in the anatase phase with lattice parameters a = b = 0.378 nm and c = 0.958 nm . The crystallite size was found to be of the order of 14 nm. The films showed reversible coloration/bleaching cycles as demonstrated by cyclic voltametry and curre...

  11. Nanostructured and nanolayer coatings based on nitrides of the metals structure study and structure and composition standard samples set development

    Directory of Open Access Journals (Sweden)

    E. B. Chabina

    2014-01-01

    Full Text Available Researches by methods of analytical microscopy and the x-ray analysis have allowed to develop a set of standard samples of composition and structure of the strengthening nanostructured and nanolayer coatings for control of the strengthening nanostructured and nanolayer coatings based on nitrides of the metals used to protect critical parts of the compressor of the gas turbine engine from dust erosion, corrosion and oxidation.

  12. Relationships between spray parameters, microstructures and ultrasonic cavitation erosion behavior of HVOF sprayed Fe-based amorphous/nanocrystalline coatings.

    Science.gov (United States)

    Qiao, Lei; Wu, Yuping; Hong, Sheng; Zhang, Jianfeng; Shi, Wei; Zheng, Yugui

    2017-11-01

    Fe-based amorphous/nanocrystalline coatings were prepared on the AISI 321 steel substrate by the high-velocity oxygen-fuel (HVOF) thermal spraying technology. The effect of selected parameters (oxygen flow, kerosene flow and spray distance) on the cavitation erosion resistance (denoted as Rc) of the coating were investigated by using the Taguchi method. Statistical tools such as design of experiments (DOE), signal-to-noise (S/N) ratio and analysis of variance (ANOVA) were used to meet the expected objective. It was concluded that the kerosene flow had greater influence on the Rc of the coating and followed by the spray distance and the oxygen flow, respectively. The optimum spray parameters (OSP) were 963L/min for the oxygen flow, 28L/h for the kerosene flow, and 330mm for the spray distance. The Rc of the coating increased with the increase of hardness or the decrease of porosity, and the hardness had a greater influence on Rc than the porosity. The Fe-based coating deposited under the OSP exhibited the best cavitation erosion resistance in distilled water. The cracks initiated at the edge of the pores and the interfaces between the un-melted or half-melted particles, and finally leaded to the delamination of the coating. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Applications of Cr-Based Metal Nitride Hard Coatings Using Multi-Magnetron Sputtering Sources and Elemental Metal Targets

    Institute of Scientific and Technical Information of China (English)

    Shicai Yang; Eric Wiemann; D.G. Teer

    2004-01-01

    Cr-based nitride hard coatings were produced by multi-magnetron sputtering sources using elemental metal materials. Cr, Ti, Mo, V, Al, and Y target materials were used for the metal sources whilst nitrogen was introduced at the same time to produce multilayer nitride hard coatings. The deposition process was optimised according to the properties of hardness, adherence and wear measured using microhardness, scratch, Rockwell indentation and pin-on-disc tests. The coatings were deposited onto hard metal carbide as well as high speed steel cutting tools such as inserts and drills. The coated inserts were tested on a wide range of difficult to machine materials using a Boehringer VDF180-C CNC lathe. The machining was performed under interrupted cutting conditions and the results were compared with those obtained using an advanced commercially available TiA1N coating. The coated carbide drills were tested under dry conditions to cut hard alloy steel and the coated tool steel drills were tested under lubricant conditions to cut carbon steel with comparing the similar tests on commercial TiN coatings. These test results were compared with those from drills coated with a commercial TiN.

  14. Applications of Cr-Based Metal Nitride Hard Coatings Using Multi-Magnetron Sputtering Sources and Elemental Metal Targets

    Institute of Scientific and Technical Information of China (English)

    ShicaiYang; EricWiemann; D.C.Teer

    2004-01-01

    Cr-based nitride hard coatings were produced by multi-magnetron sputtering sources using elemental metal materials. Cr, Ti, Mo, V, A1, and Y target materials were used for the metal sources whilst nitrogen was introduced at the same time to produce multilayer nitride hard coatings. The deposition process was optimised according to the properties of hardness, adherence and wear measured using microhardness, scratch, Rockwell indentation and pin-on-disc tests. The coatings were deposited onto hard metal carbide as well as high speed steel cutting tools such as inserts and drills. The coated inserts were tested on a wide range of difficult to machine materials using a Boehringer VDF180-C CNC lathe. The machining was performed under interrupted cutting conditions and the results were compared with those obtained using an advanced commercially available TiA1N coating. The coated carbide drills were tested under dry conditions to cut hard alloy steel and the coated tool steel drills were tested under lubricant conditions to cut carbon steel with comparing the similar tests on commercial TiN coatings. These test results were compared with those from drills coated with a commercial TiN.

  15. Enhanced Field Emission from a Carbon Nanotube Array Coated with a Hexagonal Boron Nitride Thin Film.

    Science.gov (United States)

    Yang, Xiaoxia; Li, Zhenjun; He, Feng; Liu, Mingju; Bai, Bing; Liu, Wei; Qiu, Xiaohui; Zhou, Hang; Li, Chi; Dai, Qing

    2015-08-12

    A high-quality field emission electron source made of a highly ordered array of carbon nanotubes (CNTs) coated with a thin film of hexagonal boron nitride (h-BN) is fabricated using a simple and scalable method. This method offers the benefit of reproducibility, as well as the simplicity, safety, and low cost inherent in using B(2)O(3) as the boron precursor. Results measured using h-BN-coated CNT arrays are compared with uncoated control arrays. The optimal thickness of the h-BN film is found to be 3 nm. As a result of the incorporation of h-BN, the turn-on field is found to decrease from 4.11 to 1.36 V μm(-1), which can be explained by the significantly lower emission barrier that is achieved due to the negative electron affinity of h-BN. Meanwhile, the total emission current is observed to increase from 1.6 to 3.7 mA, due to a mechanism that limits the self-current of any individual emitting tip. This phenomenon also leads to improved emission stability and uniformity. In addition, the lifetime of the arrays is improved as well. The h-BN-coated CNT array-based field emitters proposed in this work may open new paths for the development of future high-performance vacuum electronic devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Carbide and nitride precipitation during laser cladding of Inconel 718 alloy coatings

    Science.gov (United States)

    Zhang, Yaocheng; Li, Zhuguo; Nie, Pulin; Wu, Yixiong

    2013-11-01

    The microstructure of the laser clad Inconel 718 alloy coating was observed by scanning electron microscope (SEM). The chemical composition of precipitation phases was investigated by energy dispersive spectrometer (EDS) and solid phase microextraction (SPME). The crystal structure and lattice constants of precipitation are determined by transmission electron microscope (TEM). Vickers hardness of the coatings and the nanohardness of the interstitial phases were measured. The insular carbide (MC) and the tetragonal nitride (MN) with face-centered cubic (FCC) structure are rich in Ti and Nb but depleted in Ni, Fe and Cr due to the interdiffusion and redistribution of alloying elements between MC and MN and supersaturated matrix. MC and MN were precipitated in the forms of (Nb0.12Ti0.88)C1.5 and (Nb0.88Ti0.12)N1.5, and the Gibbs free energies of formation can be expressed as Δ G [ (Nb0.12Ti0.88)C1.5 ] 0 = - 122.654 - 3.1332 T (kJ /mol) and Δ G [ (Nb0.88Ti0.12)N1.5 ] 0 = - 157.814 - 3.0251 T (kJ /mol). The nanohardness and Young's modulus of the MC and MN were much higher than the matrix, and the plastic deformation energy of interstitial phases was lower than the matrix. The precipitation of MC and MN is beneficial to the mechanical properties of coating.

  17. 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.

  18. Sublimation behavior of silicon nitride /Si3N4/ coated silicon germanium /SiGe/ unicouples. [for Radioisotope Thermoelectric Generators

    Science.gov (United States)

    Stapfer, G.; Truscello, V. C.

    1975-01-01

    For the Multi-Hundred Watt (MHW) Radioisotope Thermoelectric Generator (RTG), the silicon germanium unicouples are coated with silicon nitride to minimize degradation mechanisms which are directly attributable to material sublimation effects. A program is under way to determine the effective vapor suppression of this coating as a function of temperature and gas environment. The results of weight loss experiments, using Si3N4 coated hot shoes (SiMo), operating over a temperature range from 900 C to 1200 C, are analyzed and discussed. These experiments were conducted both in high vacuum and at different pressures of carbon monoxide (CO) to determine its effect on the coating. Although the results show a favorable vapor suppression at all operating temperatures, the pressure of the CO and the thickness of the coating have a decided effect on the useful lifetime of the coating.

  19. Improved tensile and buckling behavior of defected carbon nanotubes utilizing boron nitride coating – A molecular dynamic study

    Energy Technology Data Exchange (ETDEWEB)

    Badjian, H.; Setoodeh, A.R., E-mail: setoodeh@sutech.ac.ir

    2017-02-15

    Synthesizing inorganic nanostructures such as boron nitride nanotubes (BNNTs) have led to immense studies due to their many interesting functional features such as piezoelectricity, high temperature resistance to oxygen, electrical insulation, high thermal conductivity and very long lengths as physical features. In order to utilize the superior properties of pristine and defected carbon nanotubes (CNTs), a hybrid nanotube is proposed in this study by forming BNNTs surface coating on the CNTs. The benefits of such coating on the tensile and buckling behavior of single-walled CNTs (SWCNTs) are illustrated through molecular dynamics (MD) simulations of the resulted nanostructures during the deformation. The AIREBO and Tersoff-Brenner potentials are employed to model the interatomic forces between the carbon and boron nitride atoms, respectively. The effects of chiral indices, aspect ratio, presence of mono-vacancy defects and coating dimension on coated/non-coated CNTs are examined. It is demonstrated that the coated defective CNTs exhibit remarkably enhanced ultimate strength, buckling load capacity and Young's modulus. The proposed coating not only enhances the mechanical properties of the resulted nanostructure, but also conceals it from few external factors impacting the behavior of the CNT such as humidity and high temperature.

  20. Improved tensile and buckling behavior of defected carbon nanotubes utilizing boron nitride coating - A molecular dynamic study

    Science.gov (United States)

    Badjian, H.; Setoodeh, A. R.

    2017-02-01

    Synthesizing inorganic nanostructures such as boron nitride nanotubes (BNNTs) have led to immense studies due to their many interesting functional features such as piezoelectricity, high temperature resistance to oxygen, electrical insulation, high thermal conductivity and very long lengths as physical features. In order to utilize the superior properties of pristine and defected carbon nanotubes (CNTs), a hybrid nanotube is proposed in this study by forming BNNTs surface coating on the CNTs. The benefits of such coating on the tensile and buckling behavior of single-walled CNTs (SWCNTs) are illustrated through molecular dynamics (MD) simulations of the resulted nanostructures during the deformation. The AIREBO and Tersoff-Brenner potentials are employed to model the interatomic forces between the carbon and boron nitride atoms, respectively. The effects of chiral indices, aspect ratio, presence of mono-vacancy defects and coating dimension on coated/non-coated CNTs are examined. It is demonstrated that the coated defective CNTs exhibit remarkably enhanced ultimate strength, buckling load capacity and Young's modulus. The proposed coating not only enhances the mechanical properties of the resulted nanostructure, but also conceals it from few external factors impacting the behavior of the CNT such as humidity and high temperature.

  1. The Structure and Properties of Inductively Coupled Plasma Assisted Magnetron Sputtered Nanocrystalline NbN Coatings in Corrosion Protective Die Casting Molds.

    Science.gov (United States)

    Chun, Sung-Yong

    2016-02-01

    Niobium nitride coatings for the surface modified die casting molds with various ICP powers have been prepared using ICP assisted magnetron sputtering. The applied ICP power was varied from 0 to 200 W. The deposited coatings were characterized post-deposition using X-ray diffractometry (XRD) and atomic force microscopy (AFM). Single NbN phased coatings with nano-grain sized (hardness of each coating were evaluated from potentiostat and nanoindentator. Superior corrosion protective coatings in excess of 13.9 GPa were deposited with assistance of ICP plasma during sputtering.

  2. Suppressing bacterial interaction with copper surfaces through graphene and hexagonal-boron nitride coatings.

    Science.gov (United States)

    Parra, Carolina; Montero-Silva, Francisco; Henríquez, Ricardo; Flores, Marcos; Garín, Carolina; Ramírez, Cristian; Moreno, Macarena; Correa, Jonathan; Seeger, Michael; Häberle, Patricio

    2015-04-01

    Understanding biological interaction with graphene and hexagonal-boron nitride (h-BN) membranes has become essential for the incorporation of these unique materials in contact with living organisms. Previous reports show contradictions regarding the bacterial interaction with graphene sheets on metals. Here, we present a comprehensive study of the interaction of bacteria with copper substrates coated with single-layer graphene and h-BN. Our results demonstrate that such graphitic coatings substantially suppress interaction between bacteria and underlying Cu substrates, acting as an effective barrier to prevent physical contact. Bacteria do not "feel" the strong antibacterial effect of Cu, and the substrate does not suffer biocorrosion due to bacteria contact. Effectiveness of these systems as barriers can be understood in terms of graphene and h-BN impermeability to transfer Cu(2+) ions, even when graphene and h-BN domain boundary defects are present. Our results seem to indicate that as-grown graphene and h-BN films could successfully protect metals, preventing their corrosion in biological and medical applications.

  3. Facile preparation and applications of graphitic carbon nitride coating in solid-phase microextraction.

    Science.gov (United States)

    Xu, Na; Wang, Yiru; Rong, Mingcong; Ye, Zhifeng; Deng, Zhuo; Chen, Xi

    2014-10-17

    In this study, graphitic carbon nitride (g-C3N4) was used as a coating material for solid-phase microextraction (SPME) applications. Coupled to gas chromatography (GC), the extraction ability of the SPME fiber was investigated and compared with the commercial fibers of 100 μm PDMS and 85 μm CAR/PDMS using six target analytes including deltamethrin, nerolidol, amphetamine, dodecane, ametryn and acrylamide. The g-C3N4 coating revealed excellent extraction ability and durability comparing with those of the commercial fibers due to its loose structure and unique physicochemical properties. The repeatability for each single fiber was found to be 3.46% and reproducibility for fiber to fiber was 8.53%. The g-C3N4 SPME fiber was applied to the determination of acrylamide in potato chips, the linearity and detection limit was 0.5-250 μg g(-1) and 0.018 μg g(-1), respectively.

  4. Enhanced microwave absorption properties of graphite nanoflakes by coating hexagonal boron nitride nanocrystals

    Science.gov (United States)

    Zhong, Bo; Liu, Wei; Yu, Yuanlie; Xia, Long; Zhang, Jiulin; Chai, Zhenfei; Wen, Guangwu

    2017-10-01

    We report herein the synthesis of a novel hexagonal boron nitride nanocrystal/graphite nanoflake (h-BNNC/GNF) composite through a wet-chemistry coating of graphite nanoflakes and subsequent in-situ thermal treatment process. The characterization results of X-ray diffraction, scanning electron microscope, transmission electron microscope, energy dispersive X-ray spectrum, and X-ray photoelectron spectroscopy demonstrate that h-BNNCs with diameter of tens of nanometers are highly crystallized and anchored on the surfaces of graphite nanoflakes without obvious aggregation. The minimum reflection loss (RL) value of the h-BNNC/GNF based absorbers could reach -32.38 dB (>99.99% attenuation) with the absorber thickness of 2.0 mm. This result is superior to the other graphite based and some dielectric loss microwave absorption materials recently reported. Moreover, the frequency range where the RL is less than -10 dB is 3.49-17.28 GHz with the corresponding thickness of 5.0-1.5 mm. This reveals a better electromagnetic microwave absorption performance of h-BNNC/GNFs from the X-band to the Ku-band. The remarkable enhancement of the electromagnetic microwave absorption properties of h-BNNC/GNFs can be assigned to the increase of multiple scattering, interface polarization as well as the improvement of the electromagnetic impedance matching of graphite nanoflakes after being coated with h-BNNCs.

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

    Energy Technology Data Exchange (ETDEWEB)

    Devia, D.M. [Laboratorio de Fisica del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 via al aeropuerto Campus La Nubia, Manizales (Colombia); Universidad Tecnologica de Pereira, Pereira (Colombia); Restrepo-Parra, E., E-mail: erestrepopa@unal.edu.co [Laboratorio de Fisica del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 via al aeropuerto Campus La Nubia, Manizales (Colombia); PCM Computational Applications, Universidad Nacional de Colombia Sede Manizales, Km. 9 via al aeropuerto Campus La Nubia, Manizales (Colombia); Arango, P.J. [Laboratorio de Fisica del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 via al aeropuerto Campus La Nubia, Manizales (Colombia)

    2011-11-15

    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{sub S} = 115 Degree-Sign C.

  6. Enhanced microwave absorption properties of graphite nanoflakes by coating hexagonal boron nitride nanocrystals

    KAUST Repository

    Zhong, Bo

    2017-05-31

    We report herein the synthesis of a novel hexagonal boron nitride nanocrystal/graphite nanoflake (h-BNNC/GNF) composite through a wet-chemistry coating of graphite nanoflakes and subsequent in-situ thermal treatment process. The characterization results of X-ray diffraction, scanning electron microscope, transmission electron microscope, energy dispersive X-ray spectrum, and X-ray photoelectron spectroscopy demonstrate that h-BNNCs with diameter of tens of nanometers are highly crystallized and anchored on the surfaces of graphite nanoflakes without obvious aggregation. The minimum reflection loss (RL) value of the h-BNNC/GNF based absorbers could reach −32.38dB (>99.99% attenuation) with the absorber thickness of 2.0mm. This result is superior to the other graphite based and some dielectric loss microwave absorption materials recently reported. Moreover, the frequency range where the RL is less than −10dB is 3.49-17.28GHz with the corresponding thickness of 5.0 to 1.5mm. This reveals a better electromagnetic microwave absorption performance of h-BNNC/GNFs from the X-band to the Ku-band. The remarkable enhancement of the electromagnetic microwave absorption properties of h-BNNC/GNFs can be assigned to the increase of multiple scattering, interface polarization as well as the improvement of the electromagnetic impedance matching of graphite nanoflakes after being coated with h-BNNCs.

  7. Comparative study of niobium nitride coatings deposited by unbalanced and balanced magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Olaya, J.J. [Departamento de Ingenieria Mecanica y Mecatronica, Universidad Nacional de Colombia, Bogota Colombia (Colombia); Rodil, S.E. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Mexico D. F. 04510 (Mexico); Muhl, S. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Mexico D. F. 04510 (Mexico)], E-mail: muhl@servidor.unam.mx

    2008-10-01

    Niobium nitride (NbN) coatings have many interesting properties such as chemical inertness, excellent mechanical properties, high electrical conductivity, high melting point, and a superconducting transition temperature between 16 and 17 K. For this reason, these compounds have many potential thin film applications. In this work we compare the properties of NbN{sub x} films deposited using well-characterized balanced and unbalanced magnetron sputtering systems. Samples of NbN were deposited in the two systems under almost identical deposition conditions, that is, the same substrate temperature, plasma power, gas pressure, substrate to target distance and Ar/N{sub 2} ratio. Prior to the film preparation both the magnetic field geometry and the characteristics of the plasma were determined. The microstructure and composition of the deposits were analyzed by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The corrosion resistance and the micro-abrasion wear resistance were measured by anodic polarization potentiodynamic studies and by ball cratering, respectively. The NbN films grown using the highly unbalanced magnetron configuration had a preferential (111) crystal orientation and a composite hardness of up to 2400 HV{sub 0.025}. While the films deposited using the balanced magnetron had a mixed crystalline orientation and a hardness of 2000 HV{sub 0.025}. The results demonstrate the strong effect of magnetic field configuration on the ion bombardment, and the resultant coating characteristics.

  8. Structure property relationships of nitride superlattice hard coatings prepared by pulsed laser deposition

    Science.gov (United States)

    Patel, Nitin

    Today, more than 40% of all cutting tools used in machining applications are covered with coatings. Coatings improve wear resistance, increase tool life, enable use at higher speed, and broaden the application range. Superlattices, where thin layers (typically deposited in an alternating fashion, are widely used commercially. Importantly, the hardness value of a superlattice (e.g. TiN/AlN) can significantly exceed the rule of mixture value. Superlattice coatings built from crystallographically dissimilar materials are not widely studied but hold promise for improvements in performance by allowing for both hardness and toughness to be simultaneously optimized. This is what this thesis is concerned with: a structure-property comparison of isostructural superlattices with corresponding non-isostructural superlattices. In order to grow both isostructural and non-isostructural superlattices from the same set of materials, it is necessary to grow monolithic films in different phases. Towards this end, the synthesis of different phases of AlN, (Ti,Al)N, TaN, and TiN was investigated. Films were grown by pulsed laser deposition in two different chambers that had different base pressures to study the effect of background gases on the phases and orientations of the films. Growth of AlN and (Ti,Al)N films is strongly affected in a chamber that had a base pressure of 10-6 Torr, but the films adopt their stable nitride structures in a chamber with the lower base pressure of 10-8 Torr. TaN adopts either the cubic rock salt structure or its stable hexagonal structure, depending on the growth temperature, while TiN grows as rock salt in all conditions. Single crystal epitaxial superlattices were then grown with different compositions, periodicities, and crystallographic orientations to compare the effect of chemistry, nanostructure, and crystallographic texture on hardness. Finally, the structure-property relationships of non-isostructural (cubic/hexagonal) superlattices are

  9. Anticorrosive performance of waterborne epoxy coatings containing water-dispersible hexagonal boron nitride (h-BN) nanosheets

    Science.gov (United States)

    Cui, Mingjun; Ren, Siming; Chen, Jia; Liu, Shuan; Zhang, Guangan; Zhao, Haichao; Wang, Liping; Xue, Qunji

    2017-03-01

    Homogenous dispersion of hexagonal boron nitride (h-BN) nanosheets in solvents or in the polymer matrix is crucial to initiate their many applications. Here, homogeneous dispersion of hexagonal boron nitride (h-BN) in epoxy matrix was achieved with a water-soluble carboxylated aniline trimer derivative (CAT-) as a dispersant, which was attributed to the strong π-π interaction between h-BN and CAT-, as proved by Raman and UV-vis spectra. Transmission electron microscopy (TEM) analysis confirmed a random dispersion of h-BN nanosheets in the waterborne epoxy coatings. The deterioration process of water-borne epoxy coating with and without h-BN nanosheets during the long-term immersion in 3.5 wt% NaCl solution was investigated by electrochemical measurements and water absorption test. Results implied that the introduction of well dispersed h-BN nanosheets into waterborne epoxy system remarkably improved the corrosion protection performance to substrate. Moreover, 1 wt% BN/EP composite coated substrate exhibited higher impedance modulus (1.3 × 106 Ω cm2) and lower water absorption (4%) than those of pure waterborne epoxy coating coated electrode after long-term immersion in 3.5 wt% NaCl solution, demonstrating its superior anticorrosive performance. This enhanced anticorrosive performance was mainly ascribed to the improved water barrier property of epoxy coating via incorporating homogeneously dispersed h-BN nanosheets.

  10. The effect of alumina and aluminium nitride coating by reactive magnetron sputtering on the resin bond strength to zirconia core

    OpenAIRE

    Külünk, Tolga; Külünk, Şafak; Baba, Seniha; Öztürk, Özgür; DANIŞMAN, Şengül; Savaş, Soner

    2013-01-01

    PURPOSE Although several surface treatments have been recently investigated both under in vitro and in vivo conditions, controversy still exists regarding the selection of the most appropriate zirconia surface pre-treatment. The purpose of this study was to evaluate the effect of alumina (Al) and aluminium nitride (AlN) coating on the shear bond strength of adhesive resin cement to zirconia core. MATERIALS AND METHODS Fifty zirconia core discs were divided into 5 groups; air particle abrasion...

  11. Mechanical and electrochemical properties of nanocrystalline (Mo{sub 1−x}Cr{sub x}){sub 3}Si coatings: Experimental and modeling studies

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jiang, E-mail: xujiang73@nuaa.edu.cn [Department of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016 (China); School of Mechanical and Electrical Engineering, Wuhan Institute of Technology, 693 Xiongchu Avenue, Wuhan 430073 (China); Li, ZhengYang [Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Lu, Xiaolin [Department of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016 (China); Yan, Yong [Huangshi Coal Mining Bureau Hospital, 501 Lakeside Road, Huangshi 435001 (China); Munroe, Paul [School of Materials Science and Engineering, University of New South Wales, NSW 2052 (Australia); Xie, Zong-Han [School of Mechanical and Electrical Engineering, Wuhan Institute of Technology, 693 Xiongchu Avenue, Wuhan 430073 (China); School of Mechanical Engineering, University of Adelaide, SA 5005 (Australia)

    2014-10-25

    Highlights: • Cr alloying leads to the change in preferred orientation from (2 1 0) to (2 0 0) of the coatings. • The hardness and elastic modulus of the coatings are reduced by Cr addition. • Cr alloying improves the corrosion resistance of the coatings. • Cr addition increases the Mulliken population of Mo–Mo bonds. - Abstract: Four (Mo{sub 1−x}Cr{sub x}){sub 3}Si nanocrystalline coatings with a cubic A15 structure were fabricated onto Ti–6Al–4V substrates using a double-cathode glow discharge technique. The elastic modulus and hardness of the nanocrystalline (Mo{sub 1−x}Cr{sub x}){sub 3}Si coatings were measured by nanoindentation and their electrochemical behavior was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in a 3.5 wt% NaCl solution. The results showed that the corrosion and abrasion damage resistance of the nanocrystalline (Mo{sub 1−x}Cr{sub x}){sub 3}Si coatings increased with increasing Cr addition. To gain a deeper understanding of the effect of Cr alloying on the electrochemical behavior of these (Mo{sub 1−x}Cr{sub x}){sub 3}Si coatings, the electronic structure and Mulliken populations were modeled by first-principles calculations. It revealed that the Cr alloying can enhance the protective nature of passive layers developed on the Mo{sub 3}Si coatings. The findings provide a promising foundation for the development of mechanically robust, corrosion-resistant Mo{sub 3}Si-based coatings for surface protection.

  12. Synthesis of Corrosion-resistant Nanocrystalline Nickle-copper Alloy Coatings by Pulse-plating Technique

    Directory of Open Access Journals (Sweden)

    S.K. Ghosh

    2005-01-01

    Full Text Available Bright and smooth nanocrystalline Monel-type Ni-Cu alloy gets deposited from complex citrate electrolyte by pulse electrolysis. Transmission electron microscopy studies have revealedthat the deposited Ni-Cu alloy was nanocrystalline in nature and it comprised a two-phase (fcc+Ll, mixture. The presence of twins could be seen in the nanocrystals. The Ni-Cu alloysprepared by pulse electrolysis were finer grained (- 2.5-28.5 nm than those deposited by direct current method. Nelson-Riley function has been used to calculate the lattice parameters for both the pulse current-plated and direct current-plated alloys from x-ray diffraction analysis. The microhardness values for pulse current-plated alloys were higher than for the direct currentplated alloys. The internal stresses of both the pulse current-deposited and the direct currentdeposited alloys have also been measured; the values were lower for pulse current-plated alloys. Potentiodynamic polarisation studies were carried out in aerated and deaerated neutral 3.0 Wt per cent NaCl solution and instantaneous corrosion current density of the plated alloy was determined and compared with the Monel-400 alloy. It was found that nanocrystalline pulse current-N,-35 8 Wt p;r cent copper alloy uxh~bitedlo wer instantaneous value of corros~onc urrent densirv than that of soeclrnens with direct current method and Monel-400 allov The d~ssolut~on ~ ~~~~-~ behaviour ofthe deposited nanocrystalline material was found to be more like general corrosion rather than localised corrosion as in the case of Monel-400 alloy.

  13. Redox supercapacitor performance of nanocrystalline molybdenum nitrides obtained by ammonolysis of chloride- and amide-derived precursors

    Science.gov (United States)

    Shah, S. Imran U.; Hector, Andrew L.; Owen, John R.

    2014-11-01

    Reactions of MoCl5 or Mo(NMe2)4 with ammonia result in cubic γ-Mo2N or hexagonal δ1-MoN depending on reaction time and temperature. At moderate temperatures the cubic product from Mo(NMe2)4 exhibits lattice distortions. Fairly high surface areas are observed in the porous particles of the chloride-derived materials and high capacitances of up to 275 F g-1 are observed when electrodes made from them are cycled in aqueous H2SO4 or K2SO4 electrolytes. The cyclic voltammograms suggest charge is largely stored in the electrochemical double layer at the surface of these materials. Amide-derived molybdenum nitrides have relatively low surface areas and smaller capacitances, but do exhibit strong redox features in their cyclic voltammograms, suggesting that redox capacitance is responsible for a significant proportion of the charge stored.

  14. INFLUENCE OF PLASMA NITRIDING ON THE CORROSION BEHAVIOUR AND ADHESION OF DLC COATINGS DEPOSITED ON AISI 420 STAINLESS STEEL

    Directory of Open Access Journals (Sweden)

    Jorge N. Pecina

    2016-06-01

    Full Text Available In this work the corrosion behavior and adhesion of two DLC (“Diamond Like Carbon” films (“Soft” and “Hard” were studied. Both coatings were deposited by PACVD (“Plasma Assisted Chemical Vapour Deposition” on plasma-nitrided and non-nitrided AISI 420 stainless steel. Raman spectroscopy was conducted and surface hardness was measured. The microstructure by OM and SEM, was observed. Adhesion tests were performed with C. Rockwell indentation test. Salt Spray and immersion were performed in HCl. The “Soft” coating was 20 μm thick, the “Hard” film was about 2.5 μm. The hardness was of 500 HV in the “Soft” DLC and 1400 HV in the “Hard” DLC. Both coatings presented low friction coefficient and good adhesion when they were deposited on nitrided steel. Also presented good resistance to atmospheric corrosion. HCl DLC degradation slowed rapidly introduced uncoated samples.

  15. Microstructure and tribological properties of Zr-based amorphous-nanocrystalline coatings deposited on the surface of titanium alloys by Electrospark Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Xiang; Tan, Yefa, E-mail: tanyefa7651@163.com; Zhou, Chunhua; Xu, Ting; Zhang, Zhongwei

    2015-11-30

    Highlights: • Zr-based amorphous-nanocrystalline coatings were well prepared on TC11 titanium alloys. • High glass forming ability of alloy system and high cooling rate of Electrospark Deposition process are beneficial for the generation of amorphous phase. • A model has been applied to investigate the generation of nanocrystalline phases in amorphous coating. • Excellent wear properties obtained due to nanocrystalline phases distributed in amorphous organization. - Abstract: In order to improve the wear resistance of titanium alloys, the Zr-based amorphous-nanocrystalline coatings were prepared by Electrospark Deposition (ESD) on the surface of TC11. The microstructure of the coatings was analyzed and the tribological behavior and mechanism of the coatings were investigated. The results show that the coating is mainly composed of amorphous phase Zr{sub 55}Cu{sub 30}Al{sub 10}Ni{sub 5} and distributed a large number of nano particles with the diameter between 2 nm and 4 nm such as CuZr{sub 3}, Ni{sub 2}Zr{sub 3}, NiZr{sub 2}, etc. The new alloy system made up of molten electrode material of Zr-based alloy and TC11 substrate has a large glass forming ability, which transforms to amorphous phase in the rapid heating and cooling ESD process. The long-range diffusions of atoms such as Zr and Cu in amorphous microstructure play an important role in nano nucleation growth. The coating is dense, uniform, bonding with TC11 substrate metallurgically. The thickness of the coating is from 55 μm to 60 μm and the average microhardness is 801.3 HV{sub 0.025}. The coating has good friction-reducing and anti-wear properties. The friction coefficient of the coating changes between 0.13 and 0.21 with small fluctuation, decreasing about 60% compared to that of TC11 substrate. And the wear resistance of the coating is increased by 57% than that of TC11 substrate. The main wear mechanism of the coating is micro-cutting wear accompanied with oxidation wear.

  16. A Novel Single-Step Surface-Treatment Process for Forming Cr-Nitride Coatings on Steels

    Science.gov (United States)

    Lu, X. J.; Xiang, Z. D.

    2017-02-01

    A novel single-step surface-treatment process is demonstrated for forming Cr-nitride coatings on steels. The process was carried out at 1327 K (1100 °C) for two steel grades with differing carbon concentrations. For steel grade with 0.42 to 0.5C (wt pct), the coatings formed consisted of an outer Cr2N layer and an inner Cr-carbide layer with a Cr-enriched interdiffusion zone underneath. However, for steel grade with C ≤ 0.17 wt pct, the inner Cr-carbide layer was absent.

  17. Thermal conductivity of titanium nitride/titanium aluminum nitride multilayer coatings deposited by lateral rotating cathode arc

    Energy Technology Data Exchange (ETDEWEB)

    Samani, M.K., E-mail: majid1@e.ntu.edu.sg [Novitas, Nanoelectronics Centre of Excellence, School of Electrical & Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Surface Technology Group, Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore); Research Group PLASMANT, Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp (Belgium); Ding, X.Z. [Surface Technology Group, Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore); Khosravian, N. [Research Group PLASMANT, Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp (Belgium); Amin-Ahmadi, B. [Electron Microscopy for materials Science (EMAT), Department of Physics, University of Antwerpen, Groenenborgerlan 171, B-2020 Antwerpen (Belgium); Yi, Yang [Data Storage Institute, A*STAR (Agency for Science, Technology and Research), 117608 (Singapore); Chen, G. [BC Photonics Technological Company, 5255 Woodwards Rd., Richmond, BC V7E 1G9 (Canada); Neyts, E.C.; Bogaerts, A. [Research Group PLASMANT, Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp (Belgium); Tay, B.K. [Novitas, Nanoelectronics Centre of Excellence, School of Electrical & Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2015-03-02

    A series of [TiN/TiAlN]{sub n} multilayer coatings with different bilayer numbers n = 5, 10, 25, 50, and 100 were deposited on stainless steel substrate AISI 304 by a lateral rotating cathode arc technique in a flowing nitrogen atmosphere. The composition and microstructure of the coatings have been analyzed by using energy dispersive X-ray spectroscopy, X-ray diffraction (XRD), and conventional and high-resolution transmission electron microscopy (HRTEM). XRD analysis shows that the preferential orientation growth along the (111) direction is reduced in the multilayer coatings. TEM analysis reveals that the grain size of the coatings decreases with increasing bilayer number. HRTEM imaging of the multilayer coatings shows a high density misfit dislocation between the TiN and TiAlN layers. The cross-plane thermal conductivity of the coatings was measured by a pulsed photothermal reflectance technique. With increasing bilayer number, the multilayer coatings' thermal conductivity decreases gradually. This reduction of thermal conductivity can be ascribed to increased phonon scattering due to the disruption of columnar structure, reduced preferential orientation, decreased grain size of the coatings and present misfit dislocations at the interfaces. - Highlights: • TiN/TiAlN multilayer coatings with different bilayer number were deposited on SS. • The composition and microstructure of the as-deposited coatings were analyzed. • Thermal conductivity of the coatings was measured by pulsed photothermal reflectance. • Thermal conductivity depends on the coatings' microstructure and number of layers. • With increasing the bilayer number, thermal conductivity decreased.

  18. Thermal stability of nitride solar selective absorbing coatings used in high temperature parabolic trough current

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    This paper reports a new efficient solar selective surface in high temperature application.The influence of the monolayer’s microstructure and deposition rate was firstly discussed.Then the nitride nano-multilayer on the polished stainless steel (herein after referred as "SS") substrate was prepared with Ti and Al metal targets by DC.and R.F.magnetron co-sputtering.The samples were annealed in air at different temperatures ranging from 350 to 800°C for 2 h to evaluate their thermal stability.The samples’ surface and cross-section morphology,crystal structure,phase composition,optical properties were analyzed by scanning electron microscopy,X-ray diffraction,UV-VIS-NIR spectrophotometer and infrared emissivity tester.The results show that the coatings exhibit high solar selectivity (α/ε) of 0.943/0.08 even after heat-treatment up to 400°C for 2 h in air.After heat-treatment at 600°C in air,the solar selectivity decreases to 0.92/0.16.

  19. In Vivo Biodistribution and Toxicity of Highly Soluble PEG-Coated Boron Nitride in Mice

    Science.gov (United States)

    Liu, Bo; Qi, Wei; Tian, Longlong; Li, Zhan; Miao, Guoying; An, Wenzhen; Liu, Dan; Lin, Jing; Zhang, Xiaoyong; Wu, Wangsuo

    2015-12-01

    The boron nitride (BN) nanoparticles, as the structural analogues of graphene, are the potential biomedicine materials because of the excellent biocompatibility, but their solubility and biosafety are the biggest obstacle for the clinic application. Here, we first synthesized the highly soluble BN nanoparticles coated by PEG (BN-PEG) with smaller size (~10 nm), then studied their biodistribution in vivo through radioisotope (Tc99mO4 -) labeling, and the results showed that BN-PEG nanoparticles mainly accumulated in the liver, lung, and spleen with the less uptake by the brain. Moreover, the pathological changes induced by BN-PEG could be significantly observed in the sections of the liver, lung, spleen, and heart, which can be also supported by the test of biochemical indexes in serum. More importantly, we first observed the biodistribution of BN-PEG in the heart tissues with high toxicity, which would give a warning about the cardiovascular disease, and provide some opportunities for the drug delivery and treatment.

  20. Comprehensive Evaluation of the Properties of Nanocrystalline Diamond Coatings Grown Using CVD with E/H Field Glow Discharge Stabilization

    Directory of Open Access Journals (Sweden)

    Iu. Nasieka

    2015-01-01

    Full Text Available The nanocrystalline diamond films (coatings were prepared using the plasma enhanced chemical vapor deposition (PECVD technique. In this method, direct current (DC glow discharge in the crossed E/H fields was used to activate the gas phase. The diamond coatings were deposited from the working gas mixture CH4/H2 with addition of nitrogen in various concentrations. It was ascertained that addition of N2 to the working gas mixture leads to reduction in the sizes of diamond grains as well as to the substantial decrease in the resistivity of the studied films. The electrophysical data are in good agreement with the changes induced by varying the N2 content in the Raman scattering spectra. The increase in the N2 concentration causes significant lowering of the crystalline diamond related peak and increase in the intensity of the peaks related to the sp2-bonded carbon. These changes in the spectra indicate significant disordering of the structure of prepared films and its uniformity in the nanodiamond film volume. With the great possibility, it is associated with a decrease in the sizes of diamond crystalline grains and tendency of NCD film to amorphization.

  1. The effect of nanocrystalline Ni-W coating on the tensile properties of copper

    Directory of Open Access Journals (Sweden)

    E. P. Georgiou

    2016-03-01

    Full Text Available Nanostructured Ni-W alloy coatings containing approximately 40 wt.% tungsten were electrodeposited onto copper substrates. The effect of the coatings thickness on the surface topography, microstructure and grain size was investigated with the aid of Atomic Force Microscopy (AFM, Scanning Electron Microscopy (SEM and X-ray Diffraction (XRD techniques respectively. In addition, this research work aims in understanding the influence and correlation between microstructure and thickness of these Ni-W coatings with the bulk mechanical properties of coated specimens. The experimental results indicated that the micro-hardness and Ultimate Tensile Strength (UTS of the Ni-W coated copper were higher than that of bare copper, whereas both slightly increased with increasing coating thickness up to 21 μm. On the other hand, the ductility of Ni-W coated copper decreased significantly with increasing coating thickness. Thus it could be said that when applying Ni-W coatings there are certain limitations not only in terms of their composition, but their thickness, grain size and coating structure should be also taken into consideration, in order to obtain an understanding of their mechanical behavior.

  2. Tribological behaviors of diamond-like carbon coatings on plasma nitrided steel using three BN-containing lubricants

    Energy Technology Data Exchange (ETDEWEB)

    Jia Zhengfeng [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 18 Tianshui Middle Road, Lanzhou 73000 (China); College of Materials Science and Engineering, Liaocheng University, Liaocheng 252059 (China); Graduate School of the Chinese Academy of Sciences, Beijing 10039 (China); Wang Peng [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 18 Tianshui Middle Road, Lanzhou 73000 (China); Xia Yanqiu, E-mail: xiayanqiu@yahoo.com [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 18 Tianshui Middle Road, Lanzhou 73000 (China); Zhang Haobo; Pang Xianjuan [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 18 Tianshui Middle Road, Lanzhou 73000 (China); Graduate School of the Chinese Academy of Sciences, Beijing 10039 (China); Li Bin [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 18 Tianshui Middle Road, Lanzhou 73000 (China)

    2009-04-15

    In this work, diamond-like carbon (DLC) coatings were deposited on plasma nitrided AISI 1045 steel by magnetron sputtering. Three BN-containing additives and molybdenum dithiocarbamate (MoDTC) were added to poly-alpha-olefin (PAO) as additives. The additive content (mass fraction) in PAO was fixed at 0.5 wt%. The friction and wear characters of DLC coatings on nitrided steel discs sliding against AISI 52100 steel balls were tested under the lubricated conditions. It was found that borate esters have a higher load carrying capacity and much better anti-wear and friction-reducing ability than that of MoDTC. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were employed to explore the properties of the worn surface and the mechanism of friction and wear. According to the XPS analysis, the adsorbed organic N-containing compounds and BN are, possibly, the primary reason for the novel borate esters to possess a relatively constant coefficient of friction and lower wear rate. On the other hand, possibly, the MoDTC molecules break down during sliding and produce many Mo-oxides, and then the Mo-oxides destroy the DLC coating because of its sharp edge crystalline solid structure. After destroying the DLC coating, the MoDTC react with metals and form MoS{sub 2} tribofilm, and decrease coefficient of friction of rubbing pairs.

  3. Biocompatibility studies of low temperature nitrided and collagen-I coated AISI 316L austenitic stainless steel.

    Science.gov (United States)

    Martinesi, M; Stio, M; Treves, C; Borgioli, F

    2013-06-01

    The biocompatibility of austenitic stainless steels can be improved by means of surface engineering techniques. In the present research it was investigated if low temperature nitrided AISI 316L austenitic stainless steel may be a suitable substrate for bioactive protein coating consisting of collagen-I. The biocompatibility of surface modified alloy was studied using as experimental model endothelial cells (human umbilical vein endothelial cells) in culture. Low temperature nitriding produces modified surface layers consisting mainly of S phase, the supersaturated interstitial solid solution of nitrogen in the austenite lattice, which allows to enhance surface microhardness and corrosion resistance in PBS solution. The nitriding treatment seems to promote the coating with collagen-I, without chemical coupling agents, in respect of the untreated alloy. For biocompatibility studies, proliferation, lactate dehydrogenase levels and secretion of two metalloproteinases (MMP-2 and MMP-9) were determined. Experimental results suggest that the collagen protection may be favourable for endothelial cell proliferation and for the control of MMP-2 release.

  4. Novel Nanocrystalline Intermetallic Coatings for Metal Alloys in Coal-fired Environments

    Energy Technology Data Exchange (ETDEWEB)

    Z. Zak Fang; H. Y. Sohn

    2009-08-31

    Intermetallic coatings (iron aluminide and nickel aluminide) were prepared by a novel reaction process. In the process, the aluminide coating is formed by an in-situ reaction between the aluminum powder fed through a plasma transferred arc (PTA) torch and the metal substrate (steel or Ni-base alloy). Subjected to the high temperature within an argon plasma zone, aluminum powder and the surface of the substrate melt and react to form the aluminide coatings. The prepared coatings were found to be aluminide phases that are porosity-free and metallurgically bonded to the substrate. The coatings also exhibit excellent high-temperature corrosion resistance under the conditions which simulate the steam-side and fire-side environments in coal-fired boilers. It is expected that the principle demonstrated in this process can be applied to the preparation of other intermetallic and alloy coatings.

  5. Synthesis and characterization of nanocrystalline forsterite coated poly(L-lactide-co-β-malic acid) scaffolds for bone tissue engineering applications.

    Science.gov (United States)

    Mozafari, M; Gholipourmalekabadi, M; Chauhan, N P S; Jalali, N; Asgari, S; Caicedoa, J C; Hamlekhan, A; Urbanska, A M

    2015-05-01

    In this research, after synthesizing poly(L-lactide-co-β-malic acid) (PLMA) copolymer, hybrid particles of ice and nanocrystalline forsterite (NF) as coating carriers were used to prepare NF-coated PLMA scaffolds. The porous NF-coated scaffolds were directly fabricated by a combined technique using porogen leaching and freeze-drying methods. The obtained results indicate that the scaffolds were structurally porous with NF particles on their surfaces. When compared to the uncoated scaffolds, the NF coating improved both mechanical properties as well as enhanced bioactivity of the scaffolds. In addition, in vitro biological response of the rat bone marrow stromal cells indicated that NF significantly increased the biocompatibility of NF-coated scaffolds compared with PLMA.

  6. 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.

  7. Preparation and characterization of silicon nitride (Si−N)-coated carbon fibers and their effects on thermal properties in composites

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyeon-Hye [R& D Division, Korea Institute of Carbon Convergence Technology, Jeonju 561-844 (Korea, Republic of); Nano& Advanced Materials Engineering, Jeonju University, Jeonju 560-759 (Korea, Republic of); Han, Woong [R& D Division, Korea Institute of Carbon Convergence Technology, Jeonju 561-844 (Korea, Republic of); Lee, Hae-seong [Nano& Advanced Materials Engineering, Jeonju University, Jeonju 560-759 (Korea, Republic of); Min, Byung-Gak [Department of Polymer Science & Engineering, Korea National University of Transportation, Chungju 380-702 (Korea, Republic of); Kim, Byung-Joo, E-mail: ap2-kbj@hanmail.net [R& D Division, Korea Institute of Carbon Convergence Technology, Jeonju 561-844 (Korea, Republic of)

    2015-10-15

    Graphical abstract: We report preparation and characterization of silicon nitride (Si−N)-coated carbon fibers and their effects on thermal properties in composites. Thermally composites showed enhanced thermal conductivity increasing from up to 59% by the thermal network. - Highlights: • A new method of Si−N coating on carbon fibers was reported. • Silane layer were successfully converted to Si−N layer on carbon fiber surface. • Si−N formation was confirmed by FT-IR, XPS, and EDX. • Thermal conductivity of Si−N coated CF composites were enhanced to 0.59 W/mK. - Abstract: This study investigates the effect of silicon nitride (Si−N)-coated carbon fibers on the thermal conductivity of carbon-fiber-reinforced epoxy composite. The surface properties of the Si−N-coated carbon fibers (SiNCFs) were observe using Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy, and the thermal stability was analyzed using thermogravimetric analysis. SiNCFs were fabricated through the wet thermal treatment of carbon fibers (Step 1: silane finishing of the carbon fibers; Step 2: high-temperature thermal treatment in a N{sub 2}/NH{sub 3} environment). As a result, the Si−N belt was exhibited by SEM. The average thickness of the belt were 450–500 nm. The composition of Si−N was the mixture of Si−N, Si−O, and C−Si−N as confirmed by XPS. Thermal residue of the SiNCFs in air was enhanced from 3% to 50%. Thermal conductivity of the composites increased from 0.35 to 0.59 W/mK after Si−N coating on carbon surfaces.

  8. Electric and Adsorption Characteristics of Nanocrystalline V-(N, He Coatings

    Directory of Open Access Journals (Sweden)

    Alexey G. Guglya

    2009-01-01

    Full Text Available This paper studies the structure, temperature dependences of electric resistance, and adsorption properties of nanoporous three-component V-(N, He coatings. The coatings were produced using the technique of ion beam assisted deposition, in particular, deposition of vanadium onto a titanium substrate simultaneously bombarding it with N2+He ions of 30 keV. It is shown, in contrast to V-N composites that have negative TCR (temperature coefficient of resistance, that the V-(N, He coatings have negative TCR only in the temperature range of 250 to 350∘C. A specific surface of pores and adsorption characteristics of V-(N, He composites depend on preliminary treatment of a titanium surface. A coating deposited onto an untreated substrate has specific surface of 25.5 m2/g. The preliminary irradiation of titanium with N2+He beam up to a dose of 6 × 1017 ion/cm2 provides the increase in surface area up to 57.6 m2/g. The preliminary ion bombardment provides a considerable increase in hydrogen adsorption capacity of coatings. Especially, such impact is noticeable at the room temperature, when the amount of hydrogen absorbed by a coating that was applied onto a treated surface is more than three times of that absorbed by a coating that was deposited onto nonexposed titanium.

  9. Effect of active screen plasma nitriding pretreatment on wear behavior of TiN coating deposited by PACVD technique

    Energy Technology Data Exchange (ETDEWEB)

    Raoufi, M., E-mail: raoufi@iust.ac.ir [School of Metallurgical Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Mirdamadi, Sh. [School of Metallurgical Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Mahboubi, F. [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Ahangarani, Sh. [Advanced Materials and Renewable Energies Dep., Iranian Research Organization for Science and Technology (Iran, Islamic Republic of); Mahdipoor, M.S. [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Elmkhah, H. [Department of Metallurgical Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of)

    2012-08-01

    Titanium based alloys are used extensively for improving wear properties of different parts due to their high hardness contents. Titanium nitride (TiN) is among these coatings which can be deposited on surface using various techniques such as CVD, PVD and PACVD. Their weak interface with substrate is one major drawback which can increase the total wear in spite of favorite wear behavior of TiN. Disc shaped samples from AISI H13 (DIN 1.2344) steel were prepared in this study. Single TiN coating was deposited on some of them while others have experienced a TiN deposition by active screen plasma nitriding (ASPN). Hardness at the surface and depth of samples was measured through Vickers micro hardness test which revealed 1810 Hv hardness as the maximum values for a dual-layered ASPN-TiN. Pin-on-disc wear test was done in order to study the wear mechanism. In this regard, the wear behavior of samples was investigated against pins from 100Cr6 (Din 1.3505) bearing steel and tungsten carbide-cobalt (WC-Co) steel. It was evidenced that the dual-layer ASPN-TiN coating has shown the least weight loss with the best wearing behavior because of its high hardness values, stable interface and acceptable resistance against peeling during wearing period.

  10. Microstructure and mechanical properties of titanium nitride coatings for cemented carbide cutting tools by pulsed high energy density plasma

    Institute of Scientific and Technical Information of China (English)

    PENG Zhijian; MIAO Hezhuo; QI Longhao; GONG Jianghong; YANG Size; LIU Chizi

    2003-01-01

    Hard, wear-resistant and well-adhesive titanium nitride coatings on cemented carbide cutting tools were prepared by the pulsed high energy density plasma technique at ambient temperature. The results of Auger spectra analysis indicated that the interface between the coating and substrate was more than 250 nm.Under optimized deposition conditions, the highest critical load measured by nanoscratch tester was more than 90 mN, which meant that the TiN film was well adhesive to the substrate; the highest nanohardness and Young's modulus according to nanoindentation tests were near to 27 and 450 GPa. The results of cutting tests evaluated by turning hardened CrWMn steel in industrial conditions indicated that the wear resistance and edge life of the cemented carbide tools were enhanced dramatically because of the deposition of titanium nitride coatings. These improvements were attributed to the three combined effects: the deposition and ion implantation of the pulsed plasma and the becoming finer of the grain sizes.

  11. Tribological and structural properties of titanium nitride and titanium aluminum nitride coatings deposited with modulated pulsed power magnetron sputtering

    Science.gov (United States)

    Ward, Logan

    The demand for economical high-performance materials has brought attention to the development of advanced coatings. Recent advances in high power magnetron sputtering (HPPMS) have shown to improve tribological properties of coatings. These coatings offer increased wear and oxidation resistance, which may facilitate the use of more economical materials in harsh applications. This study demonstrates the use of novel forms of HPPMS, namely modulated pulsed-power magnetron sputtering (MPPMS) and deep oscillation magnetron sputtering (DOMS), for depositing TiN and Ti1-xAlxN tribological coatings on commonly used alloys, such as Ti-6Al-4V and Inconel 718. Both technologies have been shown to offer unique plasma characteristics in the physical vapor deposition (PVD) process. High power pulses lead to a high degree of ionization compared to traditional direct-current magnetron sputtering (DCMS) and pulsed magnetron sputtering (PMS). Such a high degree of ionization was previously only achievable by cathodic arc deposition (CAD); however, CAD can lead to increased macroparticles that are unfavorable in high friction and corrosive environments. MPPMS, DOMS, and other HPPMS techniques offer unique plasma characteristics and have been shown to produce coatings with refined grain structure, improved density, hardness, adhesion, and wear resistance. Using DOMS and MPPMS, TiN and Ti1-xAlxN coatings were deposited using PMS to compare microstructures and tribological performance. For Ti1-xAlxN, two sputtering target compositions, Ti 0.5Al0.5 and Ti0.3Al0.7, were used to evaluate the effects of MPPMS on the coating's composition and tribological properties. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to characterize microstructure and crystallographic texture. Several tribological properties were evaluated including: wear rate, coefficient of friction, adhesion, and nanohardness. Results show that substrate

  12. The effect of alumina and aluminium nitride coating by reactive magnetron sputtering on the resin bond strength to zirconia core.

    Science.gov (United States)

    Külünk, Tolga; Külünk, Safak; Baba, Seniha; Oztürk, Ozgür; Danişman, Sengül; Savaş, Soner

    2013-11-01

    Although several surface treatments have been recently investigated both under in vitro and in vivo conditions, controversy still exists regarding the selection of the most appropriate zirconia surface pre-treatment. The purpose of this study was to evaluate the effect of alumina (Al) and aluminium nitride (AlN) coating on the shear bond strength of adhesive resin cement to zirconia core. Fifty zirconia core discs were divided into 5 groups; air particle abrasion with 50 µm aluminum oxide particles (Al2O3), polishing + Al coating, polishing + AlN coating, air particle abrasion with 50 µm Al2O3 + Al coating and air particle abrasion with 50 µm Al2O3 + AlN coating. Composite resin discs were cemented to each of specimens. Shear bond strength (MPa) was measured using a universal testing machine. The effects of the surface preparations on each specimen were examined with scanning electron microscope (SEM). Data were statistically analyzed by one-way ANOVA (α=.05). The highest bond strengths were obtained by air abrasion with 50 µm Al2O3, the lowest bond strengths were obtained in polishing + Al coating group (Pstrength of adhesive resin cement to zirconia core.

  13. Study on Tribological Property of the Ni-P Nanocrystalline Coating%Ni-P纳米晶镀层的摩擦学性能研究

    Institute of Scientific and Technical Information of China (English)

    张敬尧; 谈宇

    2012-01-01

    The two coatings of Ni-P amorphous and nanocrystalline structure were obtained by electroless plating. Moreover the as-deposited coatings were treated with stress-off annealing of low temperature. The composition and structure of the coatings were analyzed. Effects of anneal process and coating organize structure on tribological property of coating, as well as its inner mechanism, were studied. The result shows that the tribological property of Ni-P nanocrystalline coating is superior to that of amorphous one at the same condition(only changing the complex agent in the bath) , and different wear mechanism between the two coatings is discovered too. The excellent friction and wear alleviation coating with higher micro-hardness is obtained owing to the proper anneal process.%采用化学沉积方法获得了Ni-P纳米晶和非晶两种镀层,对镀态镀层进行低温去应力退火处理.分析了镀层成分和结构,研究了组织结构和退火工艺对镀层摩擦学性能的影响规律及其内在机制.结果表明:Ni-P纳米晶镀层的摩擦学性能明显优于同条件下(仅改变镀液中的络合剂)制备的非晶镀层,镀层磨损机制发生了变化;适当地去应力退火有助于进一步提高镀层的显微硬度,达到降磨减摩的效果.

  14. The role of nanocrystalline titania coating on nanostructured austenitic stainless steel in enhancing osteoblasts functions for regeneration of tissue

    Energy Technology Data Exchange (ETDEWEB)

    Shah, J.S.; Venkatsurya, P.K.C.; Thein-Han, W.W. [Biomaterials and Biomedical Engineering Research Laboratory, Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504 (United States); Misra, R.D.K., E-mail: dmisra@louisiana.edu [Biomaterials and Biomedical Engineering Research Laboratory, Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504 (United States); Pesacreta, T.C. [Department of Biology, University of Louisiana at Lafayette, P.O. Box 42451, Lafayette, LA 70504 (United States); Somani, M.C.; Karjalainen, L.P. [Department of Mechanical Engineering, University of Oulu, P.O. Box 4200, 90014 Oulu (Finland)

    2011-03-12

    In the context of osseointegration of metallic implants, while nanostructuring the surface favorably modulates cellular response, the disinfective attributes required during the healing process are not available. Thus, in the present study, we demonstrate that nanocrystalline titania provides cumulative benefit of enhancing osteoblasts functions to promote the efficacy of metal implants together with the disinfective attributes. To this end, the primary objective here is to examine the select functions of bone forming cells (osteoblasts) on electrocrystallized nanonodular titania-coated nanograined/ultrafine grained (NG/UFG) austenitic stainless steel. The accompanying objective is to study the disinfective/antimicrobial activity. To the best of our understanding this is the first study of nanophase titania on a non-titanium substrate. The osteoblasts functions were investigated in terms of cell attachment, proliferation, and quantitative analysis of proteins, actin and vinculin. In comparison to the bare NG/UFG substrate, the nanophase titania-coated substrate exhibited higher degree of cell attachment and proliferation which are regulated via cellular and molecular interactions with proteins, actin and vinculin. The enhanced functions of osteoblasts suggest that nanophase titania adsorbs extracellular matrix proteins, fibronectin and vitronectin from serum enhancing protein, with subsequent binding of integrins and osteoblasts precursor to titania. The antimicrobial attributes assessed in terms of degradation of methyl orange and effectiveness in killing E. coli supports the viewpoint that large surface area of titania would be instrumental in reducing the detrimental effect of biologically reactive oxygen species produced by macrophages in the vicinity of the metal bone/implant interface. In summary, the study provides some new insights concerning nanostructuring of metallic substrates with specific physical and surface properties for medical devices with

  15. Field electron emission of diamond films on nanocrystalline diamond coating by CVD method

    Institute of Scientific and Technical Information of China (English)

    CAI Rangqi; CHEN Guanghua; SONG Xuemei; XING Guangjian; FENG Zhenjian; HE Deyan

    2003-01-01

    The preparation process, structure feature and field electron emission characteristic of diamond films on nanocyrstalline diamond coating by the CVD method were studied. The field electron emission measurements on the samples showed that the diamond films have lower turn-on voltage and higher field emission current density. A further detailed theory explanation to the results was given.

  16. Electrodeposition and corrosion resistance of nanocrystalline white bronze (CuSn) coatings

    NARCIS (Netherlands)

    Hovestad, A.; Lekka, M.; Willemsen, R.M.R.; Tacken, R.A.; Bonora, P.L.

    2008-01-01

    For jewellery applications electroplated white bronze (CuSn) was investigated as undercoating for noble metal finishes as alternative to nickel. A strongly acidic plating bath was developed with an organic additive to suppress hydrogen evolution and obtain bright coatings. An electrochemical study o

  17. Electrodeposition and corrosion resistance of nanocrystalline white bronze (CuSn) coatings

    NARCIS (Netherlands)

    Hovestad, A.; Lekka, M.; Willemsen, R.M.R.; Tacken, R.A.; Bonora, P.L.

    2008-01-01

    For jewellery applications electroplated white bronze (CuSn) was investigated as undercoating for noble metal finishes as alternative to nickel. A strongly acidic plating bath was developed with an organic additive to suppress hydrogen evolution and obtain bright coatings. An electrochemical study

  18. Comparative study on microstructure, crystallite size and lattice strain of as-deposited and thermal treatment silver silicon nitride coating on Ti6Al4V alloy

    Science.gov (United States)

    Zalilah, Umi; Mahmoodian, R.

    2017-06-01

    Silver silicon nitride coating were deposited on Ti6Al4V alloy using physical vapor deposition magnetron sputtering technique. Field Emission Spectroscopy (FESEM), Electron Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD) were used to characterize as-deposited and after heat treatment of AgSiN coatings in order to understand the morphology, compositions and structure. Meanwhile, in determining the crystallite size and lattice strain, the simplified Williamson-Hall plot method was utilized. The heat treated coated sample shown to reveal granular surface structure, bigger crystallite size and lattice strain as compared to the as-deposited coated sample.

  19. Stability of an Electrodeposited Nanocrystalline Ni-Based Alloy Coating in Oil and Gas Wells with the Coexistence of H2S and CO2

    Directory of Open Access Journals (Sweden)

    Yiyong Sui

    2017-06-01

    Full Text Available The stability of an electrodeposited nanocrystalline Ni-based alloy coating in a H2S/CO2 environment was investigated by electrochemical measurements, weight loss method, and surface characterization. The results showed that both the cathodic and anodic processes of the Ni-based alloy coating were simultaneously suppressed, displaying a dramatic decrease of the corrosion current density. The corrosion of the Ni-based alloy coating was controlled by H2S corrosion and showed general corrosion morphology under the test temperatures. The corrosion products, mainly consisting of Ni3S2, NiS, or Ni3S4, had excellent stability in acid solution. The corrosion rate decreased with the rise of temperature, while the adhesive force of the corrosion scale increased. With the rise of temperature, the deposited morphology and composition of corrosion products changed, the NiS content in the corrosion scale increased, and the stability and adhesive strength of the corrosion scale improved. The corrosion scale of the Ni-based alloy coating was stable, compact, had strong adhesion, and caused low weight loss, so the corrosion rates calculated by the weight loss method cannot reveal the actual oxidation rate of the coating. As the corrosion time was prolonged, the Ni-based coating was thinned while the corrosion scale thickened. The corrosion scale was closely combined with the coating, but cannot fully prevent the corrosive reactants from reaching the substrate.

  20. Modification of the structure and properties of commercially pure titanium through nitriding and subsequent TiN coating deposition in a single vacuum cycle

    Science.gov (United States)

    Ivanov, Yu F.; Krysina, O. V.; Petrikova, E. A.; Shugurov, V. V.; Tolkachev, O. S.; Teresov, A. D.; Koval, N. N.

    2017-05-01

    The modification of titanium by ion plasma methods consisting of hard coatings deposition on a specimen surface subjected to nitriding is carried out. It is shown that complex modification of the titanium in a single vacuum cycle is followed by formation of multilayered multiphase structure which tribological properties multiply exceed the corresponding properties of the material treated on two vacuum separated setups.

  1. Nanocrystalline ZnO film deposited by ultrasonic spray on textured silicon substrate as an anti-reflection coating layer

    Energy Technology Data Exchange (ETDEWEB)

    Sali, S., E-mail: samira_sali@yahoo.fr [Silicon Technology Development Unit (UDTS), 02 Bd, Frantz FANON, B.P. 140, Algiers (Algeria); Houari Boumediene University (USTHB), Faculty of Physics, Algiers (Algeria); Boumaour, M. [Silicon Technology Development Unit (UDTS), 02 Bd, Frantz FANON, B.P. 140, Algiers (Algeria); Kechouane, M. [Houari Boumediene University (USTHB), Faculty of Physics, Algiers (Algeria); Kermadi, S.; Aitamar, F. [Silicon Technology Development Unit (UDTS), 02 Bd, Frantz FANON, B.P. 140, Algiers (Algeria)

    2012-07-01

    A ZnO thin film was successfully synthesized on glass, flat surface and textured silicon substrates by chemical spray deposition. The textured silicon substrate was carried out using two solutions (NaOH/IPA and Na{sub 2}CO{sub 3}). Textured with Na{sub 2}CO{sub 3} solution, the sample surface exhibits uniform pyramids with an average height of 5 {mu}m. The properties and morphology of ZnO films were investigated. X-ray diffraction (XRD) spectra revealed a preferred orientation of the ZnO nanocrystalline film along the c-axis where the low value of the tensile strain 0.26% was obtained. SEM images show that all films display a granular, polycrystalline morphology. The morphology of the ZnO layers depends dramatically on the substrate used and follows the contours of the pyramids on the substrate surface. The average reflectance of the textured surface was found to be around 13% and it decreases dramatically to 2.57% after deposition of a ZnO antireflection coating. FT-IR peaks arising from the bonding between Zn-O are clearly represented using a silicon textured surface. A very intense photoluminescence (PL) emission peak is observed for ZnO/textured Si, revealing the good quality of the layer. The PL peak at 380.5 nm (UV emission) and the high-intensity PL peak at 427.5 nm are observed and a high luminescence occurs when using a textured Si substrate.

  2. Methods of forming boron nitride

    Science.gov (United States)

    Trowbridge, Tammy L; Wertsching, Alan K; Pinhero, Patrick J; Crandall, David L

    2015-03-03

    A method of forming a boron nitride. The method comprises contacting a metal article with a monomeric boron-nitrogen compound and converting the monomeric boron-nitrogen compound to a boron nitride. The boron nitride is formed on the same or a different metal article. The monomeric boron-nitrogen compound is borazine, cycloborazane, trimethylcycloborazane, polyborazylene, B-vinylborazine, poly(B-vinylborazine), or combinations thereof. The monomeric boron-nitrogen compound is polymerized to form the boron nitride by exposure to a temperature greater than approximately 100.degree. C. The boron nitride is amorphous boron nitride, hexagonal boron nitride, rhombohedral boron nitride, turbostratic boron nitride, wurzite boron nitride, combinations thereof, or boron nitride and carbon. A method of conditioning a ballistic weapon and a metal article coated with the monomeric boron-nitrogen compound are also disclosed.

  3. Methods of forming boron nitride

    Energy Technology Data Exchange (ETDEWEB)

    Trowbridge, Tammy L; Wertsching, Alan K; Pinhero, Patrick J; Crandall, David L

    2015-03-03

    A method of forming a boron nitride. The method comprises contacting a metal article with a monomeric boron-nitrogen compound and converting the monomeric boron-nitrogen compound to a boron nitride. The boron nitride is formed on the same or a different metal article. The monomeric boron-nitrogen compound is borazine, cycloborazane, trimethylcycloborazane, polyborazylene, B-vinylborazine, poly(B-vinylborazine), or combinations thereof. The monomeric boron-nitrogen compound is polymerized to form the boron nitride by exposure to a temperature greater than approximately 100.degree. C. The boron nitride is amorphous boron nitride, hexagonal boron nitride, rhombohedral boron nitride, turbostratic boron nitride, wurzite boron nitride, combinations thereof, or boron nitride and carbon. A method of conditioning a ballistic weapon and a metal article coated with the monomeric boron-nitrogen compound are also disclosed.

  4. Effect of titanium nitride/titanium coatings on the stress corrosion of nickel-titanium orthodontic archwires in artificial saliva

    Science.gov (United States)

    Liu, Jia-Kuang; Liu, I.-Hua; Liu, Cheng; Chang, Chen-Jung; Kung, Kuan-Chen; Liu, Yen-Ting; Lee, Tzer-Min; Jou, Jin-Long

    2014-10-01

    The purpose of this investigation was to develop titanium nitride (TiN)/titanium (Ti) coating on orthodontic nickel-titanium (NiTi) wires and to study the stress corrosion of specimens in vitro, simulating the intra-oral environment in as realistic a manner as possible. TiN/Ti coatings were formed on orthodontic NiTi wires by physical vapor deposition (PVD). The characteristics of untreated and TiN/Ti-coated NiTi wires were evaluated by measurement of corrosion potential (Ecorr), corrosion current densities (Icorr), breakdown potential (Eb), and surface morphology in artificial saliva with different pH and three-point bending conditions. From the potentiodynamic polarization and SEM results, the untreated NiTi wires showed localized corrosion compared with the uniform corrosion observed in the TiN/Ti-coated specimen under both unstressed and stressed conditions. The bending stress influenced the corrosion current density and breakdown potential of untreated specimens at both pH 2 and pH 5.3. Although the bending stress influenced the corrosion current of the TiN/Ti-coated specimens, stable and passive corrosion behavior of the stressed specimen was observed even at 2.0 V (Ag/AgCl). It should be noted that the surface properties of the NiTi alloy could determine clinical performance. For orthodontic application, the mechanical damage destroys the protective oxide film of NiTi; however, the self-repairing capacity of the passive film of NiTi alloys is inferior to Ti in chloride-containing solutions. In this study, the TiN coating was found able to provide protection against mechanical damage, while the Ti interlayer improved the corrosion properties in an aggressive environment.

  5. Microstructure and tribological properties of Zr-based amorphous-nanocrystalline coatings deposited on the surface of titanium alloys by Electrospark Deposition

    Science.gov (United States)

    Hong, Xiang; Tan, Yefa; Zhou, Chunhua; Xu, Ting; Zhang, Zhongwei

    2015-11-01

    In order to improve the wear resistance of titanium alloys, the Zr-based amorphous-nanocrystalline coatings were prepared by Electrospark Deposition (ESD) on the surface of TC11. The microstructure of the coatings was analyzed and the tribological behavior and mechanism of the coatings were investigated. The results show that the coating is mainly composed of amorphous phase Zr55Cu30Al10Ni5 and distributed a large number of nano particles with the diameter between 2 nm and 4 nm such as CuZr3, Ni2Zr3, NiZr2, etc. The new alloy system made up of molten electrode material of Zr-based alloy and TC11 substrate has a large glass forming ability, which transforms to amorphous phase in the rapid heating and cooling ESD process. The long-range diffusions of atoms such as Zr and Cu in amorphous microstructure play an important role in nano nucleation growth. The coating is dense, uniform, bonding with TC11 substrate metallurgically. The thickness of the coating is from 55 μm to 60 μm and the average microhardness is 801.3 HV0.025. The coating has good friction-reducing and anti-wear properties. The friction coefficient of the coating changes between 0.13 and 0.21 with small fluctuation, decreasing about 60% compared to that of TC11 substrate. And the wear resistance of the coating is increased by 57% than that of TC11 substrate. The main wear mechanism of the coating is micro-cutting wear accompanied with oxidation wear.

  6. Influence of Nitrided Layer on The Properties of Carbon Coatings Produced on X105CrMo17 Steel Under DC Glow-Discharge Conditions

    Directory of Open Access Journals (Sweden)

    Tomasz BOROWSKI

    2016-09-01

    Full Text Available In most cases, machine components, which come in contact with each other, are made of steel. Common steel types include 100Cr6 and X105CrMo17 are widely used in rolling bearings, which are subjected to high static loads. However, more and more sophisticated structural applications require increasingly better performance from steel. The most popular methods for improving the properties of steel is carburisation or nitriding. Unfortunately, when very high surface properties of steel are required, this treatment may be insufficient. Improvement of tribological properties can be achieved by increasing the hardness of the surface, reducing roughness or reducing the coefficient of friction. The formation of composite layers on steel, consisting of a hard nitride diffusion layer and an external carbon coating with a low coefficient of friction, seems to be a prospect with significant potential. The article describes composite layers produced on X105CrMo17 steel and defines their morphology, surface roughness and their functional properties such as: resistance to friction-induced wear, coefficient of friction and corrosion resistance. The layers have been formed at a temperature of 370°C in successive processes of: nitriding in low-temperature plasma followed by deposition of a carbon coating under DC glow-discharge conditions. An evaluation was also made of the impact of the nitrided layers on the properties and morphology of the carbon coatings formed by comparing them to coatings formed on non-nitrided X105CrMo17 steel substrates. A study of the surface topography, adhesion, resistance to friction-induced wear and corrosion shows the significant importance of the substrate type the carbon coatings are formed on.DOI: http://dx.doi.org/10.5755/j01.ms.22.3.7532

  7. Improved tribological properties, electrochemical resistance and biocompatibility of AISI 316L stainless steel through duplex plasma nitriding and TiN coating treatment.

    Science.gov (United States)

    Kao, Wen-Hsien; Su, Yean-Liang; Horng, Jeng-Haur; Hsieh, Yun-Ting

    2017-07-01

    AISI 316L specimens were nitrided using a low temperature (390℃) plasma nitriding process and then coated with a thin layer of titanium nitride by closed field unbalanced magnetron sputtering. The microstructure, adhesion properties and hardness of the duplex-treated samples were examined using X-ray diffraction, scratch testing and nanoindentation, respectively. In addition, the tribological properties were investigated by means of reciprocating wear tests performed against 316L, Si3N4 and Ti6Al4V balls under a load of 10 N for 24 min in 0.9% NaCl solution. The electrochemical resistance of the samples was evaluated by potentiodynamic polarisation tests. Finally, the biocompatibility of the samples was investigated by seeding purified mouse leukemic monocyte macrophage cells (Raw 264.7) on the sample surface for one, three and five days, respectively. In general, the results showed that the duplex nitriding and titanium nitride coating process significantly improved the tribological properties, electrochemical resistance and biocompatibility of the AISI 316L samples.

  8. The Corrosion and Wear Performance of Microcrystalline WC-10Co-4Cr and Near-Nanocrystalline WC-17Co High Velocity Oxy-Fuel Sprayed Coatings on Steel Substrate

    Science.gov (United States)

    Saha, Gobinda C.; Khan, Tahir I.

    2010-11-01

    The study of near-nanocrystalline cermet composite coating was performed by depositing near-nanocrystalline WC-17Co powder using the high velocity oxy-fuel spraying technique. The WC-17Co powder consists of a core with an engineered near-nano-scale WC dispersion with a mean grain size 427 nm. The powder particle contains 6 wt pct of the ductile phase Co matrix mixed into the core to ensure that the reinforcing ceramic phase WC material is discontinuous to limit debridement during wear, while the remainder of the binding phase (11 wt pct) is applied as a coating on the powder particle to improve the ductility. The tribological properties of the coating, in terms of corrosion resistance, microhardness, and sliding abrasive wear, were studied and compared with those of an industrially standard microcrystalline WC-10Co-4Cr coating with a WC mean grain size 3 μm. Results indicated that the WC-17Co coating had superior wear and corrosion resistance compared to the WC-10Co-4Cr coating. The engineered WC-17Co powder with a duplex Co layer had prevented significant decarburization of the WC dispersion in the coating, thereby reducing the intersplat microporosity necessary for initiating microgalvanic cells. The improved wear resistance was attributed to the higher hardness value of the near-nanocrystalline WC-17Co coating.

  9. Improved multicrystalline silicon ingot quality using single layer silicon beads coated with silicon nitride as seed layer

    Science.gov (United States)

    babu, G. Anandha; Takahashi, Isao; Matsushima, Satoru; Usami, Noritaka

    2016-05-01

    We propose to utilize single layer silicon beads (SLSB) coated with silicon nitride as cost-effective seed layer to grow high-quality multicrystalline silicon (mc-Si) ingot. The texture structure of silicon nitride provides a large number of nucleation sites for the fine grain formation at the bottom of the crucible. No special care is needed to prevent seed melting, which would lead to decrease of red zone owing to decrease of feedstock melting time. As we expected, mc-Si ingot seeded with SLSB was found to consist of small, different grain orientations, more uniform grain distribution, high percentage of random grain boundaries, less twin boundaries, and low density of dislocation clusters compared with conventional mc-Si ingot grown under identical growth conditions. These results show that the SLSB seeded mc-Si ingot has enhanced ingot quality. The correlation between grain boundary structure and defect structure as well as the reason responsible for dislocation clusters reduction in SLSB seeded mc-Si wafer are also discussed.

  10. Effects of Duplex Nitriding and TiN Coating Treatment on Wear Resistance, Corrosion Resistance and Biocompatibility of Ti6Al4V Alloy

    Science.gov (United States)

    Kao, W. H.; Su, Y. L.; Hsieh, Y. T.

    2017-08-01

    Ti6Al4V alloy substrates were nitrided at 900 °C. TiN coatings were then deposited on the nitrided substrates using a closed-field unbalanced magnetron sputtering system. The microstructure, hardness and adhesion properties of the TiN-N-Ti6Al4V substrates were evaluated and compared with those of an untreated Ti6Al4V sample, a nitrided Ti6Al4V sample and a TiN-coated Ti6Al4V sample, respectively. The tribological properties of the various samples were investigated by means of reciprocating sliding wear tests performed in 0.9 wt.% NaCl solution against 316L, Si3N4 and Ti6Al4V balls, respectively. In addition, the corrosion resistance was evaluated using potentiodynamic polarization tests. Finally, the biocompatibility of the samples was investigated by observing the attachment and growth of purified mouse leukemic monocyte/macrophage cells (Raw 264.7) on the sample surface after culturing periods of 24, 72 and 120 h, respectively. Overall, the results showed that the duplex nitriding/TiN coating treatment significantly improved the tribological, anti-corrosion and biocompatibility properties of the original Ti6Al4V alloy.

  11. Long-term cycle stability at a high current for nanocrystalline LiFePO4 coated with a conductive polymer

    Science.gov (United States)

    Dinh, Hung-Cuong; Lim, Hanjo; Park, Ki Dong; Yeo, In-Hyeong; Kang, Yongku; Mho, Sun-il

    2013-03-01

    Highly uniform hierarchical-microstructured LiFePO4 particles with dumbbell- and donut-shape and individual LiFePO4 nanocrystals were prepared by a hydrothermal method utilizing citric acid or a triblock copolymer (Pluronic P123) as a surfactant. The cathode composed of the individual nanocrystalline LiFePO4 particles exhibited higher specific capacity than the cathodes composed of the hierarchically assembled microparticles. Coating a conductive polymer, poly-3,4-ethylenedioxythiophene (PEDOT), on the surface of LiFePO4 particles improved the battery performances such as large specific capacities, high rate capability and an improved cycle stability. The nanocrystalline LiFePO4 particles coated with PEDOT (20 wt%) exhibited the highest discharge capacities of 175 and 136 mAh g-1 for the first battery cycle and 163 and 128 mAh g-1 after 500 battery cycles, with a degradation rate of 6-7%, at the rates of 1 and 10 C, respectively.

  12. Improvement Of Tools Durability By Application Of Hybrid Layer Of Nitrided/PECVD Coating.

    OpenAIRE

    Gronostajski Z.; Kaszuba M.; Paschke H.; Zakrzewski T.; Rogaliński G.

    2015-01-01

    In the process of die hot forging the tools are subjected to three main factors leading to their destruction: the intensive thermal shocks, cyclically variable mechanical loads and intensive friction. The above mentioned factors causing destruction in the process of hot forging and warm forging concern mainly the surface of tools. Hybrid technique nitrided/PECVD belong to the latest methods of modifying the properties of the surface layer. In the paper the application of this technique for fo...

  13. Corrosion resistance of zirconium oxynitride coatings deposited via DC unbalanced magnetron sputtering and spray pyrolysis-nitriding

    Energy Technology Data Exchange (ETDEWEB)

    Cubillos, G.I., E-mail: gcubillos@unal.edu.co [Department of Chemistry, Group of Materials and Chemical Processes, Universidad Nacional de Colombia, Av. Cra. 30 No 45-03, Bogotá (Colombia); Bethencourt, M., E-mail: manuel.bethencourt@uca.es [Department of Materials Science, Metallurgy Engineering and Inorganic Chemistry, International Campus of Excellence of the Sea - CEI-MAR, University of Cadiz, Avda. República Saharaui s/n, 11510 Puerto Real, Cádiz (Spain); Olaya, J.J., E-mail: jjolayaf@unal.edu.co [Faculty of Engineering, Group of Materials and Chemical Processes, Universidad Nacional de Colombia, Av. Cra. 30 No 45-03, Bogotá (Colombia)

    2015-02-01

    Highlights: • New ZrO{sub x}N{sub y} films were deposited on stainless steel 316L using PSY-N and UBMS. • ZrO{sub x}N{sub y} rhombohedral polycrystalline film grew with PSY-N. • Zr{sub 2}ON{sub 2} crystalline structures, mostly oriented along the (2 2 2) plane, grew with UBMS. • Layers improved corrosion behavior in NaCl media, especially those deposited by UBMS. - Abstract: ZrO{sub x}N{sub y}/ZrO{sub 2} thin films were deposited on stainless steel using two different methods: ultrasonic spray pyrolysis-nitriding (SPY-N) and the DC unbalanced magnetron sputtering technique (UBMS). Using the first method, ZrO{sub 2} was initially deposited and subsequently nitrided in an anhydrous ammonia atmosphere at 1023 K at atmospheric pressure. For UBMS, the film was deposited in an atmosphere of air/argon with a Φair/ΦAr flow ratio of 3.0. Structural analysis was carried out through X-ray diffraction (XRD), and morphological analysis was done through scanning electron microscopy (SEM) and atomic force microscopy (AFM). Chemical analysis was carried out using X-ray photoelectron spectroscopy (XPS). ZrO{sub x}N{sub y} rhombohedral polycrystalline film was produced with spray pyrolysis-nitriding, whereas using the UBMS technique, the oxynitride films grew with cubic Zr{sub 2}ON{sub 2} crystalline structures preferentially oriented along the (2 2 2) plane. Upon chemical analysis of the surface, the coatings exhibited spectral lines of Zr3d, O1s, and N1s, characteristic of zirconium oxynitride/zirconia. SEM analysis showed the homogeneity of the films, and AFM showed morphological differences according to the deposition technique of the coatings. Zirconium oxynitride films enhanced the stainless steel's resistance to corrosion using both techniques. The protective efficacy was evaluated using electrochemical techniques based on linear polarization (LP). The results indicated that the layers provide good resistance to corrosion when exposed to chloride

  14. Subtask 6.6 - SiAION Coatings for Alkali-Resistant Silicon Nitride. Topical report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-02-25

    The efficiency of a gas turbine can be improved by increasing operating temperature. Construction materials should both meet high strength requirements and exhibit hot alkali corrosion resistance. Structural ceramics based on silicon nitride are promising candidates for high temperature engineering applications because of their high strength and good resistance to corrosion. Their performance varies significantly with the mechanical properties of boundary phases which, in turn, depend on their chemical composition, thickness of the amorphous phase, and the deformation process. To make silicon nitride ceramics tough, SiAlON ceramics were developed with controlled crystallization of the amorphous grain boundary phase. Crystallization of the grain boundary glass improves the high temperature mechanical properties of silicon nitride ceramics. Thus, the knowledge of silicon oxynitride ceramics corrosion behavior in Na{sub 2}SO{sub 4} becomes important for engineers in designing appropriate part for turbines working at high temperatures. So far there has been no report concerning alkali attack on SiAlON ceramics in the presence of SO{sub 2} and chlorine in flue gas. The goal of this project was to investigate alkali corrosion of SiAlON-Y structural ceramics under combustion conditions in the presence of sodium derived components.

  15. Physical and mechanical characteristics and chemical compatibility of aluminum nitride insulator coatings for fusion reactor applications

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Rink, D.L. [Argonne National Lab., IL (United States). Energy Technology Div.

    1996-04-01

    The blanket system is one of the most important components in a fusion reactor because it has a major impact on both the economics and safety of fusion energy. The primary functions of the blanket in a deuterium/tritium-fueled fusion reactor are to convert the fusion energy into sensible heat and to breed tritium for the fuel cycle. The Blanket Comparison and Selection Study, conducted earlier, described the overall comparative performance of various concepts, including liquid metal, molten salt, water, and helium. Based on the requirements for an electrically insulating coating on the first-wall structural material to minimize the MHD pressure drop during the flow of liquid metal in a magnetic field, AlN was selected as a candidate coating material for the Li self-cooled blanket concept. This report discusses the results from an ongoing study of physical and mechanical characteristics and chemical compatibility of AlN electrical insulator coatings in a liquid Li environment. Details are presented on the AlN coating fabrication methods, and experimental data are reported for microstructures, chemistry of coatings, pretreatment of substrate, heat treatment of coatings, hardness data for coatings, coating/lithium interactions, and electrical resistance before and after exposure to lithium. Thermodynamic calculations are presented to establish regions of stability for AlN coatings in an Li environment as a function of O concentration and temperature, which can aid in-situ development of AlN coatings in Li.

  16. Hexagonal Boron Nitride Coated Carbon Nanotubes: Interlayer Polarization Improved Field Emission.

    Science.gov (United States)

    Chang, Han-Chen; Tsai, Hsin-Jung; Lin, Wen-Yi; Chu, Yung-Chi; Hsu, Wen-Kuang

    2015-07-08

    Coating of h-BN onto carbon nanotubes induces polarization at interfaces, and charges become localized at N and C atoms. Field emission of coated tubes is found to be highly stable, and current density fluctuates within 4%. Study further reveals that the electric field established between coatings and tubes facilitates charge transfer across interfaces and electrons are emitted through occupied and unoccupied bands of N and B atoms.

  17. 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.

  18. Investigation of some microstructural features related to corrosion initiation in titanium-aluminium nitride coated steel

    Energy Technology Data Exchange (ETDEWEB)

    Ronkainen, H. (Technical Research Centre of Finland (VTT), Espoo (Finland)); Ehrnsten, U. (Technical Research Centre of Finland (VTT), Espoo (Finland)); Zilliacus, R. (Technical Research Centre of Finland (VTT), Espoo (Finland)); Saarilahti, J. (Technical Research Centre of Finland (VTT), Espoo (Finland)); Mahiout, A. (Technical Research Centre of Finland (VTT), Espoo (Finland)); Hannula, S.P. (Technical Research Centre of Finland (VTT), Espoo (Finland))

    1992-11-20

    In this work the microstructural features and defects identified previously in corrosion and porosity tests of the coatings were studied. The influence of surface roughness was evaluated with (Ti, Al)N coatings on two different types of substrates. Coatings deposited on the roughest surfaces on either a high speed steel or a stainless steel had the highest porosity. However, the dependence of the porosity on the surface roughness was not straightforward. Interrupted coating runs were carried out to obtain more information on the initiation of defects in the substrate-coating interface. Samples produced in the interrupted runs were analysed using metallographic methods, scanning electron microscopy with X-ray analysis, Rutherford backscattering spectrometry and secondary ion mass spectroscopy. Sputtering was found to be effective in removing the impurities from the interface and none of the non-metallic elements (carbon, oxygen, sulphur) studied exhibited any enrichment on the interface. The use of a tungsten filament for enhancement of the plasma was found to result in a tungsten-enriched layer at the substrate-coating interface, which may have an effect on adhesion and corrosion properties of the coating. However, no droplet types of formations were detected after sputter cleaning or when either titanium or aluminium evaporation was started, suggesting that tungsten was evenly distributed in the coating. (orig.)

  19. Silicides and Nitrides Formation in Ti Films Coated on Si and Exposed to (Ar-N2-H2 Expanding Plasma

    Directory of Open Access Journals (Sweden)

    Isabelle Jauberteau

    2017-02-01

    Full Text Available The physical properties including the mechanical, optical and electrical properties of Ti nitrides and silicides are very attractive for many applications such as protective coatings, barriers of diffusion, interconnects and so on. The simultaneous formation of nitrides and silicides in Ti films improves their electrical properties. Ti films coated on Si wafers are heated at various temperatures and processed in expanding microwave (Ar-N2-H2 plasma for various treatment durations. The Ti-Si interface is the centre of Si diffusion into the Ti lattice and the formation of various Ti silicides, while the Ti surface is the centre of N diffusion into the Ti film and the formation of Ti nitrides. The growth of silicides and nitrides gives rise to two competing processes which are thermodynamically and kinetically controlled. The effect of thickness on the kinetics of the formation of silicides is identified. The metastable C49TiSi2 phase is the main precursor of the stable C54TiSi2 phase, which crystallizes at about 600 °C, while TiN crystallizes at about 800 °C.

  20. The Role of Diffusion Media in Nitriding Process on Surface Layers Characteristics of AISI 4140 with and without Hard Chrome Coatings

    Directory of Open Access Journals (Sweden)

    K.A. Widi

    2016-09-01

    Full Text Available The surface layer characteristics of the AISI 4140 tool steel treated by nitriding gas before and after hard chrome plating utilizing pure nitrogen diffusion media (fluidized bed reactor and the without gas (muffle reactor has been studied experimentally. The result shows that nitriding substrate with hard chrome layers has nitrogen atoms concentration almost twice greater than that without hard chrome layers. After being given a hard chrome plating, nitriding on AISI 4140 steel generally has a nitrogen concentration of up to 4 times more than the substrate without hard chrome coating. Almost the entire specimen showed the highest concentration of N atoms in the area below the surface (hardening depth of 200 to 450 µm. N atoms diffusion depth profile has a correlation with hardening depth profile, especially on the specimens layered with hard chromium. The substrate without hard chrome plating tends to have higher surface hardness than the sub-surface. The results show that the effectiveness and efficiency of the gas nitriding diffusion process can be produced without the use of gas in the muffle reactor but the specimens must be hard chromium coated first. This phenomenon can be explained by the role of the passive layer formation that works as a barrier to keeps the spreading of N atoms concentrated in sub-surface areas.

  1. Improvement Of Tools Durability By Application Of Hybrid Layer Of Nitrided/PECVD Coating.

    Directory of Open Access Journals (Sweden)

    Gronostajski Z.

    2015-09-01

    Full Text Available In the process of die hot forging the tools are subjected to three main factors leading to their destruction: the intensive thermal shocks, cyclically variable mechanical loads and intensive friction. The above mentioned factors causing destruction in the process of hot forging and warm forging concern mainly the surface of tools. Hybrid technique nitrided/PECVD belong to the latest methods of modifying the properties of the surface layer. In the paper the application of this technique for forging tools of constant velocity joint body is presented. The durability of the new tools is much better than the tools applied so far.

  2. An investigation of the typical corrosion parameters used to test polymer electrolyte fuel cell bipolar plate coatings, with titanium nitride coated stainless steel as a case study

    Science.gov (United States)

    Orsi, A.; Kongstein, O. E.; Hamilton, P. J.; Oedegaard, A.; Svenum, I. H.; Cooke, K.

    2015-07-01

    Stainless steel bipolar plates (BPP) for polymer electrolyte membrane fuel cells (PEMFCs) have good manufacturability, durability and low costs, but inadequate corrosion resistance and elevated interfacial contact resistance (ICR) in the fuel cell environment. Thin film coatings of titanium nitride (TiN) of 1 μm in thickness, were deposited by means of physical vapour deposition (PVD) process on to stainless steel (SS) 316L substrates and were evaluated, in a series of tests, for their level of corrosion protection and ICR. In the ex-situ corrosion tests, variables such as applied potential, experimental duration and pH of the sulphate electrolyte at 80 °C were altered. The ICR values were found to increase after exposure to greater applied potentials and electrolytes of a higher pH. In terms of experimental duration, the ICR increased most rapidly at the beginning of each experiment. It was also found that the oxidation of TiN was accelerated after exposure to electrolytes of a higher pH. When coated BPPs were incorporated into an accelerated fuel cell test, the degradation of the fuel cell cathode resembled the plates that were tested at the highest anodic potential (1.4 VSHE).

  3. MoS2-coated microspheres of self-sensitized carbon nitride for efficient photocatalytic hydrogen generation under visible light irradiation

    Science.gov (United States)

    Gu, Quan; Sun, Huaming; Xie, Zunyuan; Gao, Ziwei; Xue, Can

    2017-02-01

    We have successfully coated the self-sensitized carbon nitride (SSCN) microspheres with a layer of MoS2 through a facile one-pot hydrothermal method by using (NH4)2MoS4 as the precursor. The resulted MoS2-coated SSCN photocatalyst appears as a core-shell structure and exhibits enhanced visible-light activities for photocatalytic H2 generation as compared to the un-coated SSCN and the standard g-C3N4 reference with MoS2 coating. The photocatalytic test results suggest that the oligomeric s-triazine dyes on the SSCN surface can provide additional light-harvesting capability and photogenerated charge carriers, and the coated MoS2 layer can serve as active sites for proton reduction towards H2 evolution. This synergistic effect of surface triazine dyes and MoS2 coating greatly promotes the activity of carbon nitride microspheres for vishible-light-driven H2 generation. This work provides a new way of future development of low-cost noble-metal-free photocatalysts for efficient solar-driven hydrogen production.

  4. Constructing Novel Fiber Reinforced Plastic (FRP) Composites through a Biomimetic Approach: Connecting Glass Fiber with Nanosized Boron Nitride by Polydopamine Coating

    OpenAIRE

    XueMei Wen; ZaoZao Xiao; Tao Jiang; Jian Li; Wei Zhang; Lei Zhang; Huaiqi Shao

    2013-01-01

    A biomimetic method was developed to construct novel fiber reinforced plastic (FRP) composites. By mimicking mussel adhesive proteins, a monolayer of polydopamine was coated on glass fiber (GF) surface. The polydopamine-treated GF (D-GF) adsorbed boron nitride (BN) nanoparticles, while obtaining micronano multiscale hybrid fillers BN-D-GF. Scanning electron microscopy (SEM) results showed that the strong interfacial interaction brought by the polydopamine benefits the loading amount as well ...

  5. Silicon Carbide/Boron Nitride Dual In-Line Coating of Silicon Carbide Fiber Tows Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I project will demonstrate monolayer and dual layer coating of SiC fiber by leveraging Laser Chemical Vapor Deposition techniques developed by Free...

  6. X-ray elastic constants and residual stress of textured titanium nitride coating

    Energy Technology Data Exchange (ETDEWEB)

    Sue, J.A. (Union Carbide Coatings Service Corp., Indianapolis, IN (United States))

    1992-11-16

    X-ray elastic constants for the (422) and (333)/(511) reflections of the [l brace]111[r brace] textured TiN coating were determined. The coating exhibited high elastic anisotropy. The X-ray elastic constant of the (422) reflection was comparable with those predicted from single crystal elastic compliances on the basis of the Voigt and Reuss models, whereas a significant deviation from these models was found for (333)/(511). The residual stress of the coating was determined by X-ray diffraction and bi-metal deflection techniques. The magnitude of residual stress in the coating calculated using the measured X-ray elastic constants was in good agreement with these two reflections and, within experimental scatter, the values were also consistent with those obtained from the deflection measurement.

  7. Study on the coating of nano-scale SiO2 film on the surface of nanocrystalline Mg-Al layered double hydroxides

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zejiang; MEI Xiujuan; XU Chenghua; QIU Fali

    2005-01-01

    The coating process of a nano-scale SiO2 film on the nanocrystalline Mg-Al layered double hydroxides via a sol-gel process was investigated. The uniform and dense SiO2 film with a thickness of about 5 nm on the nano-LDHs particles was characterized by the solubility test in the dilute HNO3 or HCl acid, TEM and FT-IR, XRD, TG and DSC. The chemical shifts of binding energies of Al 2p, Mg 2p, Si 2s and O 1s on the coated particles indicate that the coating of the SiO2 nano-film on the surface of the nano-LDHs proceeds through the formation of Mg-O-Si and Al-O-Si bonds. The thermal analysis shows that both the SiO2-coated nano-LDHs and the nano-LDHs have a similar mass loss process, in which there are three obvious stages of mass loss in the temperature range of 40-700℃. Furthermore, the more the coated amount of SiO2 on the surface of the nano-LDHs is, the less the mass loss of the samples is at 700℃.The nano- LDHs have two obvious endothermic peaks at 244.67℃ and 430.13℃, whose corresponding heat absorption capacities are 412.28 J/g and 336.30 J/g, respectively. In contrast, the coated nano-LDHs have only one endothermic peak at 243.60℃ with a heat absorption capacity of 221.25 J/g.

  8. Biological applications of nanocrystalline diamond

    OpenAIRE

    Williams, Oliver; Daenen, Michael; Haenen, Ken

    2007-01-01

    Nanocrystalline diamond films have generated substantial interest in recent years due to their low cost, extreme properties and wide application arena. Diamond is chemically inert, has a wide electrochemical window and is stable in numerous harsh environments. Nanocrystalline diamond has the advantage of being readily grown on a variety of substrates at very low thickness, resulting in smooth conformal coatings with high transparency. These films can be doped from highly insulating to metalli...

  9. STUDY ON Al-BASED AMORPHOUS AND NANOCRYSTALLINE COMPOSITE COATING%铝基非晶纳米晶复合涂层研究

    Institute of Scientific and Technical Information of China (English)

    梁秀兵; 张志彬; 陈永雄; 徐滨士

    2012-01-01

    An Al-Ni-Y-Co amorphous and nanocrystalline composite coating was prepared on the surface of the AZ91 Mg alloy by using an automatic high velocity arc spraying system. Its microstructures were analyzed by scanning electron microscope (SEM), X-ray diffraction (XRD) and transmission electron microscope (TEM). The results show that the coatings compose of amorphous, nanocrystalline and microcrystalline phases, which has a compact structure with low porosity about 1.8%. The average Vickers microhardness and bond strength of this coating are 311.7 HVo 1 and 26.8 MPa. Its relative wear resistance is about 10 times than that of Al coating and 6 times than that of AZ91 magnesium alloy. The corrosion potential of this coating is more positive than that of Al coating and AZ91 magnesium alloy, and the corresponding corrosion current density value is about 1/2 the same as that of Al coating and 1/5 as that of AZ91 Mg alloy. Especially, compared with the surface on corroded Al coating and AZ91 Mg alloy, the corroded Al-Ni-Y-Co coating has a more flattered surface with less corrosive piting than Al coating. It is confirmed that the Al-Ni-Y-Co coating is an excellent coatinig with higher wear-resistance and corrosion resistance.%采用自动化高速电弧喷涂系统,用自行研制的粉芯丝材,在AZ91镁合金基体表面上制备出Al-Ni-Y-Co非晶纳米晶复合涂层.采用扫描电子显微镜(SEM).X射线衍射仪(XRD)、透射电子显微镜(TEM)分析了A1-Ni-Y-Co非晶纳米晶复合涂层的微观形貌和组织结构,结果表明Al-Ni-Y-Co非晶纳米晶复合涂层是由非晶相和纳米晶化相共同组成的,涂层结构致密,孔隙率约为1.8%.Al-Ni-Y-Co非晶纳米晶复合涂层的平均显微Vickers硬度值为311.7 HV0.1,结合强度为26.8 MPa.涂层的抗磨损耐腐蚀性能优于Al涂层和AZ91镁合金基体;其相对耐磨性约为Al涂层的10倍,为AZ91镁合金的6倍;其自腐蚀电位值正于Al涂层及AZ91镁合金,自腐蚀电

  10. Chitosan-coated boron nitride nanospheres enhance delivery of CpG oligodeoxynucleotides and induction of cytokines

    Directory of Open Access Journals (Sweden)

    Zhang H

    2013-05-01

    Full Text Available Huijie Zhang,1,2 Song Chen,3 Chunyi Zhi,4 Tomohiko Yamazaki,1,2 Nobutaka Hanagata1,2,5 1Graduate School of Life Science, Hokkaido University, Sapporo, Japan; 2Biomaterials Unit, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Ibaraki, Japan; 3Japanese Society for the Promotion of Science, Tokyo, Japan; 4Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, People’s Republic of China; 5Nanotechnology Innovation Station, Ibaraki, Japan Background: Cytosine-phosphate-guanine (CpG oligodeoxynucleotides activate Toll-like receptor 9, leading to induction of proinflammatory cytokines, which play an important role in induction and maintenance of innate and adaptive immune responses. Previously, we have used boron nitride nanospheres (BNNS as a carrier for delivery of unmodified CpG oligodeoxynucleotides to activate Toll-like receptor 9. However, because CpG oligodeoxynucleotides and BNNS are both negatively charged, electrostatic repulsion between them is likely to reduce the loading of CpG oligodeoxynucleotides onto BNNS. Therefore, the efficiency of uptake of CpG oligodeoxynucleotides is also limited and does not result in induction of a robust cytokine response. To ameliorate these problems, we developed a CpG oligodeoxynucleotide delivery system using chitosan-coated BNNS as a carrier. Methods: To facilitate attachment of CpG oligodeoxynucleotides onto the BNNS and improve their loading capacity, we prepared positively charged BNNS by coating them with chitosan preparations of three different molecular weights and used them as carriers for delivery of CpG oligodeoxynucleotides. Results: The zeta potentials of the BNNS-CS complexes were positive, and chitosan coating improved their dispersity and stability in aqueous solution compared with BNNS. The positive charge of the BNNS-CS complexes greatly improved the loading capacity and cellular uptake efficiency of Cp

  11. Improvement of orthodontic friction by coating archwire with carbon nitride film

    Energy Technology Data Exchange (ETDEWEB)

    Wei Songbo [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Shao Tianmin, E-mail: shaotm@mail.tsinghua.edu.cn [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Ding Peng [Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing 100081 (China)

    2011-10-01

    In order to reduce frictional resistance between archwire and bracket during orthodontic tooth movement, carbon nitride (CNx) thin films were deposited on the surface of archwires with ion beam assisted deposition (IBAD). The energy-dispersive X-ray spectrometer (EDS) analysis showed that the CNx film was successfully deposited on the surface of the orthodontic wires. X-ray photoelectron spectroscopy (XPS) analysis suggested that the deposited CNx film was sp{sup 2} carbon dominated structures, and diversiform bonds (N-C, N{identical_to}C, et al.) coexisted in the film. The friction tests indicated that the CNx film significantly reduced the wire-bracket friction both in ambient air and in artificial saliva. The sp{sup 2}C rich structure of the CNx film as well as its protection function for the archwire was responsible for the low friction of the wire-bracket sliding system.

  12. Synthesis and characterization of zirconium nitride coatings by cathodic arc sputtering technique

    Energy Technology Data Exchange (ETDEWEB)

    Sarwar, M.N.; Awan, M.S.; Akbar, S. [ISIT, Islamabad (Pakistan)

    2014-11-15

    Polycrystalline zirconium nitride films (560 nm) were deposited on stainless steel (SS-316) substrates using the multi-target cathodic arc sputtering technique. Deposition was carried out under N{sub 2} reactive atmosphere (4 x 10{sup -3} mbar) at two different temperatures, 150 and 200 C. X-ray diffraction studies show that reflections from planes changed from (111) to (200) for deposition temperatures of 150 C and 200 C, respectively. Films deposited at 150 C and 200 C bear a critical load of 6.4 N and 6.8 N respectively, showing better adherence at higher temperature. This may be the result of film-substrate diffusion at the interface.

  13. Structure and Properties of Vacuum Arc Single-Layer and Multiperiod Two-Layer Nitride Coatings Based on Ti(Al:Si Layers

    Directory of Open Access Journals (Sweden)

    V.M. Beresnev

    2017-02-01

    Full Text Available The paper provides an analysis of impact of deposition conditions on structural and phase state and thermal stability of vacuum arc coatings based on Ti(Al:Si layers. We studied single-phase single-layer coatings, and multiperiod bilayer coatings with second phase nitride interlayers of one of the following three metals: Mo, Cr or Zr. It was established that hexagonal and cubic lattices may form in the coatings when transition to the cubic lattice occurs with Al content of about 25 at. %. Presence of second nanoscale (7-8 nm layers in bilayer multiperiod compositions, which consist of one nitride from CrNx, MoNx or ZrNx group, does not change the type of lattice in [Ti(Al:Si]Nx layers. Also, an fcc lattice with a strong or weak texture [111] forms in CrNx and ZrNx layers, while crystallites with hexagonal lattice form in MoNx layers. High-temperature annealing at 700 °С during 40 minutes leads to a significant (by 23 % or up to Н  47.56 GPa increase in microhardness of coating of the [Ti(Al]Nx/ZrNy system due to formation of a nano-size structure with an average size of crystallites of 3.6 nm in [Ti(Al]Nx layers, and 6.3 nm in ZrNx layers.

  14. Direct access to macroporous chromium nitride and chromium titanium nitride with inverse opal structure.

    Science.gov (United States)

    Zhao, Weitian; DiSalvo, Francis J

    2015-03-21

    We report a facile synthesis of single-phase, nanocrystalline macroporous chromium nitride and chromium titanium nitride with an inverse opal morphology. The material is characterized using XRD, SEM, HR-TEM/STEM, TGA and XPS. Interconversion of macroporous CrN to Cr2O3 and back to CrN while retaining the inverse opal morphology is also demonstrated.

  15. Possibilities of Increase of Adhesion of the Cubic Boron Nitride Coatings by Applying an Interfacial Layers

    Institute of Scientific and Technical Information of China (English)

    MaciejKupczyk

    2004-01-01

    In the work the chosen investigations of the adhesion force of thin, superhard coatings to the cutting edges made of cemented carbides are presented. For identification of the adhesion force of coatings to substrate an automatic scratch tester constructed at Poznan University of Technology was applied. The estimation of the adhesion force (value of critical load measured during scratch test) was carried out on the base of the vibration signal. Results of investigations are pointed at the influence of a surface preparation (degreasing, etching, low and high-temperature sputtering) on a critical load values. It was round that the most effective method for surface preparation is low temperature sputtering. The influence of the TiC+Al2O3+TiN interracial layer on increase of the adhesion force of BN coating to cemented carbides substrate was observed.

  16. Possibilities of Increase of Adhesion of the Cubic Boron Nitride Coatings by Applying an Interfacial Layers

    Institute of Scientific and Technical Information of China (English)

    Maciej Kupczyk

    2004-01-01

    In the work the chosen investigations of the adhesion force of thin, superhard coatings to the cutting edges made of cemented carbides are presented. For identification of the adhesion force of coatings to substrate an automatic scratch tester constructed at Poznan University of Technology was applied. The estimation of the adhesion force (value of critical load measured during scratch test) was carried out on the base of the vibration signal. Results of investigations are pointed at the influence of a surface preparation (degreasing, etching, low and high-temperature sputtering) on a critical load values.It was found that the most effective method for surface preparation is low temperature sputtering. The influence of the TiC+Al2O3+TiN interfacial layer on increase of the adhesion force of BN coating to cemented carbides substrate was observed.

  17. Quantifying Friction Effects of Molybdenum Disulfide, Tungsten Disulfide, Hexagonal Boron Nitride, and Lubalox as Bullet Coating

    Science.gov (United States)

    2012-07-30

    also claims that these coatings eliminate copper fouling of the barrel. The Swedish ammunition company Norma Precision advertises friction reduction...Lubricant,” US Patent 6036996. [7] Norma , 2011. “ Norma Diamond Line.” http://www.norma.cc/en/Products/Our-Brands/ Norma - Diamond-Line/ Accessed

  18. Microstructure and wear resistance of Ti-Cu-N composite coating prepared via laser cladding/laser nitriding technology on Ti-6Al-4V alloy

    Science.gov (United States)

    Yang, Yuling; Cao, Shiyin; Zhang, Shuai; Xu, Chuan; Qin, Gaowu

    2017-07-01

    Ti-Cu-N coatings with three different Cu contents on Ti-6Al-4V alloy (TC4) were obtained via laser cladding together with laser nitriding (LC/LN) technology. Phase constituents, microstructure, microhardness, and wear resistance of the coatings were investigated. The evolution of the coefficients of friction for the three coatings was measured under dry sliding conditions as a function of the revolutions until the coating failure. The results show that the coatings are mainly composed of TiN, CuTi3 and some TiO6 phases dispersed in the matrix. A good metallurgical bonding between the coating and substrate has been successfully obtained. The prepared Ti-Cu-N composite coatings almost doubly enhance the microhardness of the TC4 alloy and reduce the friction down to 1/4-1/2 of the TC4 alloy, and thus significantly improve the wear resistance. The coefficient of friction depends on the Cu content in the coating.

  19. Boron nitride nanotubes coated with organic hydrophilic agents: Stability and cytocompatibility studies

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Tiago Hilário; Soares, Daniel Crístian Ferreira; Moreira, Luciana Mara Costa; Ornelas da Silva, Paulo Roberto [Serviço de Nanotecnologia, Centro de Desenvolvimento da Tecnologia Nuclear CDTN/CNEN, Avenida Presidente Antônio Carlos, 6.627, Campus da UFMG, Pampulha, CEP 31270-901 Belo Horizonte, Minas Gerais (Brazil); Gouvêa dos Santos, Raquel [Laboratório de Radiobiologia, Centro de Desenvolvimento da Tecnologia Nuclear CNEN/CDTN, Av. Presidente Antônio Carlos 6.627, Campus da UFMG, Pampulha, 31270-901 Belo Horizonte, Minas Gerais (Brazil); Barros de Sousa, Edésia Martins, E-mail: sousaem@cdtn.br [Serviço de Nanotecnologia, Centro de Desenvolvimento da Tecnologia Nuclear CDTN/CNEN, Avenida Presidente Antônio Carlos, 6.627, Campus da UFMG, Pampulha, CEP 31270-901 Belo Horizonte, Minas Gerais (Brazil)

    2013-12-01

    In the present study, Boron Nitride Nanotubes (BNNTs) were synthesized and functionalized with organic hydrophilic agents constituted by glucosamine (GA), polyethylene glycol (PEG){sub 1000}, and chitosan (CH) forming new singular systems. Their size, distribution, and homogeneity were determined by photon correlation spectroscopy, while their surface charge was determined by laser Doppler anemometry. The morphology and structural organization were evaluated by Transmission Electron Microscopy. The functionalization was evaluated by Thermogravimetry analysis and Fourier Transformer Infrared Spectroscopy. The results showed that BNNTs were successfully obtained and functionalized, reaching a mean size and dispersity deemed adequate for in vitro studies. The in vitro stability tests also revealed a good adhesion of functionalized agents on BNNT surfaces. Finally, the in vitro cytocompatibility of functionalized BNNTs against MCR-5 cells was evaluated, and the results revealed that none of the different functionalization agents disturbed the propagation of normal cells up to the concentration of 50 μg/mL. Furthermore, in this concentration, no significantly chromosomal or morphologic alterations or increase in ROS (Reactive Oxygen Species) could be observed. Thus, findings from the present study reveal an important stability and cytocompatibility of functionalized BNNTs as new potential drugs or radioisotope nanocarriers to be applied in therapeutic procedures. - Highlights: • BNNTs were synthesized and functionalized with organic hydrophilic agents. • Hydrophilic molecules do not alter the biocompatibility profile of BNNTs. • No significantly chromosomal or morphologic alterations in ROS could be observed.

  20. In vitro response of human peripheral blood mononuclear cells to AISI 316L austenitic stainless steel subjected to nitriding and collagen coating treatments.

    Science.gov (United States)

    Stio, Maria; Martinesi, Maria; Treves, Cristina; Borgioli, Francesca

    2015-02-01

    Surface modification treatments can be used to improve the biocompatibility of austenitic stainless steels. In the present research two different modifications of AISI 316L stainless steel were considered, low temperature nitriding and collagen-I coating, applied as single treatment or in conjunction. Low temperature nitriding produced modified surface layers consisting mainly of S phase, which enhanced corrosion resistance in PBS solution. Biocompatibility was assessed using human peripheral blood mononuclear cells (PBMC) in culture. Proliferation, lactate dehydrogenase (LDH) levels, release of cytokines (TNF-α, IL-1β, IL-12, IL-10), secretion of metalloproteinase (MMP)-9 and its inhibitor TIMP-1, and the gelatinolytic activity of MMP-9 were determined. While the 48-h incubation of PBMC with all the sample types did not negatively influence cell proliferation, LDH and MMP-9 levels, suggesting therefore a good biocompatibility, the release of the pro-inflammatory cytokines was always remarkable when compared to that of control cells. However, in the presence of the nitrided and collagen coated samples, the release of the pro-inflammatory cytokine IL-1β decreased, while that of the anti-inflammatory cytokine IL-10 increased, in comparison with the untreated AISI 316L samples. Our results suggest that some biological parameters were ameliorated by these surface treatments of AISI 316L.

  1. Effects of Ti-C:H coating and plasma nitriding treatment on tribological, electrochemical, and biocompatibility properties of AISI 316L.

    Science.gov (United States)

    Kao, W H; Su, Y L; Horng, J H; Zhang, K X

    2016-08-01

    Ti-C:H coatings were deposited on original, nitrided, and polished-nitrided AISI 316L stainless steel substrates using a closed field unbalanced magnetron sputtering system. Sliding friction wear tests were performed in 0.89 wt.% NaCl solution under a load of 30 N against AISI 316L stainless steel, Si3N4, and Ti6Al4V balls, respectively. The electrochemical properties of the various specimens were investigated by means of corrosion tests performed in 0.89 wt.% NaCl solution at room temperature. Finally, the biocompatibility properties of the specimens were investigated by performing cell culturing experiments using purified mouse leukemic monocyte macrophage cells (Raw264.7). In general, the results showed that plasma nitriding followed by Ti-C:H coating deposition provides an effective means of improving the wear resistance, anti-corrosion properties, and biocompatibility performance of AISI 316L stainless steel. © The Author(s) 2016.

  2. Nanocrystalline diamond films for biomedical applications

    DEFF Research Database (Denmark)

    Pennisi, Cristian Pablo; Alcaide, Maria

    2014-01-01

    performance of nanocrystalline diamond films is reviewed from an application-specific perspective, covering topics such as enhancement of cellular adhesion, anti-fouling coatings, non-thrombogenic surfaces, micropatterning of cells and proteins, and immobilization of biomolecules for bioassays. In order......Nanocrystalline diamond films, which comprise the so called nanocrystalline diamond (NCD) and ultrananocrystalline diamond (UNCD), represent a class of biomaterials possessing outstanding mechanical, tribological, and electrical properties, which include high surface smoothness, high corrosion...... resistance, chemical inertness, superior electrochemical behavior, biocompatibility, and nontoxicity. These properties have positioned the nanocrystalline diamond films as an attractive class of materials for a range of therapeutic and diagnostic applications in the biomedical field. Consequently...

  3. Optical and structural properties of nanocrystalline anatase (TiO{sub 2}) thin films prepared by non-aqueous sol-gel dip-coating

    Energy Technology Data Exchange (ETDEWEB)

    Haimi, E., E-mail: eero.haimi@tkk.fi [Department of Materials Science and Engineering, Aalto University, P.O. Box 16200, FI-00076 Aalto (Finland); Lipsonen, H.; Larismaa, J. [Department of Materials Science and Engineering, Aalto University, P.O. Box 16200, FI-00076 Aalto (Finland); Kapulainen, M. [VTT, Technical Research Centre of Finland, Tietotie 3, Espoo P.O. Box 1000, FI-02044 VTT (Finland); Krzak-Ros, J. [Institute of Materials Science and Applied Mechanics, Wroclaw University of Technology, PL-50371, Wroclaw (Poland); Hannula, S.-P. [Department of Materials Science and Engineering, Aalto University, P.O. Box 16200, FI-00076 Aalto (Finland)

    2011-07-01

    Anatase (TiO{sub 2}) thin films were grown by non-aqueous sol-gel dip-coating using titanium (IV) n-butoxide as precursor and 1-butanol as solvent. High withdrawal speed of 4.7 mm/s in dip-coating resulted in defect free films of 100 nm average film thickness after subsequent heat treatments. According to scanning electron microscope and X-ray diffraction measurements, the films consisted of nanocrystalline anatase with 30 nm mean crystallite size. Refractive index n({lambda}) and extinction coefficient k({lambda}) were determined over the wavelength range from 200 to 1650 nm. The optical band gap of the film material was approximately 3.2 eV. The results showed very similar optical characteristics to those that are accomplished with chemically more reactive aqueous sol-gel processes. Furthermore, it was found that in addition to porosity, coordination number of Ti atoms to nearest oxygen neighbors is likely to have a significant role in explaining differences of optical properties between bulk anatase and thin film materials of the present work.

  4. Role of nanocrystalline ZnO coating on the stability of porous silicon formed on textured (1 0 0) Si

    Science.gov (United States)

    Verma, Daisy; Sharma, Shailesh N.; Kharkwal, Aneeta; Bhagavannarayana, G.; Kumar, Mahesh; Singh, Shiv Nath; Singh, Parakram Kumar; Mehdib, Syed Sazad; Husain, Mushahid

    2013-11-01

    In this study, a colloid of nanocrystalline ZnO particles prepared by chemical route is sprayed on porous silicon layers. Porosity and thickness of PS layers were estimated by gravimetric analysis. Upon adsorption of ZnO colloids on PS films, oxidation of nanocrystalline Si causes shrinkage of the Si-core due to the breaking of SiSi bonds resulting in a blue-shift in PL spectra. The PL blue-shift can also be related to SiO species or due to defects and the silica networks on which OH groups are absorbed due to ZnO incorporation as also supported by our Fourier transform infrared (FTIR) and X-ray photoelectron (XPS) studies, respectively. From high resolution X-ray diffraction (HRXRD) studies, a better crystalline perfection and considerable reduction in stress/strain values were observed for PS/ZnO layers as compared to virgin PS layers. The changes in the chemical composition at the surface of PS upon adsorption of ZnO colloids as elucidated by FTIR and XPS studies could be responsible for different PL emission and lattice-mismatch characteristics. The improved stability properties of PS are attributed to the strong absorption/adsorption of ZnO into the highly porous vertical layers separating macroscopic domains of nanoporous silicon and the mechanism of light emission from PS/ZnO layers is discussed on the basis of proposed energy band gap diagram.

  5. Influence of substrate pre-treatments by Xe{sup +} ion bombardment and plasma nitriding on the behavior of TiN coatings deposited by plasma reactive sputtering on 100Cr6 steel

    Energy Technology Data Exchange (ETDEWEB)

    Vales, S., E-mail: sandra.vales@usp.br [Universidade de São Paulo (USP), Escola de Engenharia de São Carlos, Av. Trabalhador São Carlense 400, São Carlos, SP CEP 13566-590 (Brazil); Brito, P., E-mail: ppbrito@gmail.com [Pontifícia Universidade Católica de Minas Gerais (PUC-MG), Av. Dom José Gaspar 500, 30535-901 Belo Horizonte, MG (Brazil); Pineda, F.A.G., E-mail: pipe8219@gmail.com [Universidade de São Paulo (USP), Escola de Engenharia de São Carlos, Av. Trabalhador São Carlense 400, São Carlos, SP CEP 13566-590 (Brazil); Ochoa, E.A., E-mail: abigail_ochoa@hotmail.com [Universidade Estadual de Campinas (UNICAMP), Campus Universitário Zeferino Vaz, Barão Geraldo, Campinas, SP CEP 13083-970 (Brazil); Droppa, R., E-mail: roosevelt.droppa@ufabc.edu.br [Universidade Federal do ABC (UFABC), Av. dos Estados, 5001, Santo André, SP CEP 09210-580 (Brazil); Garcia, J., E-mail: jose.garcia@sandvik.com [Sandvik Coromant R& D, Lerkrogsvägen 19, SE-12680, Stockholm (Sweden); Morales, M., E-mail: monieriz@gmail.com [Universidade Estadual de Campinas (UNICAMP), Campus Universitário Zeferino Vaz, Barão Geraldo, Campinas, SP CEP 13083-970 (Brazil); Alvarez, F., E-mail: alvarez@ifi.unicamp.br [Universidade Estadual de Campinas (UNICAMP), Campus Universitário Zeferino Vaz, Barão Geraldo, Campinas, SP CEP 13083-970 (Brazil); and others

    2016-07-01

    In this paper the influence of pre-treating a 100Cr6 steel surface by Xe{sup +} ion bombardment and plasma nitriding at low temperature (380 °C) on the roughness, wear resistance and residual stresses of thin TiN coatings deposited by reactive IBAD was investigated. The Xe{sup +} ion bombardment was carried out using a 1.0 keV kinetic energy by a broad ion beam assistance deposition (IBAD, Kaufman cell). The results showed that in the studied experimental conditions the ion bombardment intensifies nitrogen diffusion by creating lattice imperfections, stress, and increasing roughness. In case of the combined pre-treatment with Xe{sup +} ion bombardment and subsequent plasma nitriding, the samples evolved relatively high average roughness and the wear volume increased in comparison to the substrates exposed to only nitriding or ion bombardment. - Highlights: • Effect of Xe ion bombardment and plasma nitriding on TiN coatings was investigated. • Xe ion bombardment with 1.0 KeV increases nitrogen retention in plasma nitriding. • 1.0 KeV ion impact energy causes sputtering, thus increasing surface roughness. • TiN coating wear is minimum after plasma nitriding due to lowest roughness.

  6. Graphitic carbon nitride (g-C3N4) coated titanium oxide nanotube arrays with enhanced photo-electrochemical performance.

    Science.gov (United States)

    Sun, Mingxuan; Fang, Yalin; Kong, Yuanyuan; Sun, Shanfu; Yu, Zhishui; Umar, Ahmad

    2016-08-09

    Herein, we report the successful formation of graphitic carbon nitride coated titanium oxide nanotube array thin films (g-C3N4/TiO2) via the facile thermal treatment of anodized Ti sheets over melamine. The proportion of C3N4 and TiO2 in the composite can be adjusted by changing the initial addition mass of melamine. The as-prepared samples are characterized by several techniques in order to understand the morphological, structural, compositional and optical properties. UV-vis absorption studies exhibit a remarkable red shift for the g-C3N4/TiO2 thin films as compared to the pristine TiO2 nanotubes. Importantly, the prepared composites exhibit an enhanced photocurrent and photo-potential under both UV-vis and visible light irradiation. Moreover, the observed maximum photo-conversion efficiency of the prepared composites is 1.59 times higher than that of the pristine TiO2 nanotubes. The optical and electrochemical impedance spectra analysis reveals that the better photo-electrochemical performance of the g-C3N4/TiO2 nanotubes is mainly due to the wider light absorption and reduced impedance compared to the bare TiO2 nanotube electrode. The presented work demonstrates a facile and simple method to fabricate g-C3N4/TiO2 nanotubes and clearly revealed that the introduction of g-C3N4 is a new and innovative approach to improve the photocurrent and photo-potential efficiencies of TiO2.

  7. Fabrication and optical property of silicon oxide layer coated semiconductor gallium nitride nanowires.

    Science.gov (United States)

    Zhang, Jun; Zhang, Lide; Jiang, Feihong; Yang, Yongdong; Li, Jianping

    2005-01-13

    Quasi one-dimensional GaN-SiO(2) nanostructures, with a silicon oxide layer coated on semiconductor GaN nanowires, were successfully synthesized through as-synthesized SiO(2) nanoparticles-assisted reaction. The experimental results indicate that the nanostructure consists of single-crystalline wurtzite GaN nanowire core, an amorphous SiO(2) outer shell separated in the radial direction. These quasi one-dimensional nanowires have the diameters of a few tens of nanometers and lengths up to several hundreds of micrometers. The photoluminescence spectrum of the GaN-SiO(2) nanostructures consists of one broad blue-light emission peak at 480 nm and another weak UV emission peak at 345 nm. The novel method, which may results in high yield and high reproducibility, is demonstrated to be a unique technique for producing nanostructures with controlled morphology.

  8. Structural changes in ZrO{sub x}N{sub y}/ZrO{sub 2} coatings deposited through spray pyrolysis-nitriding

    Energy Technology Data Exchange (ETDEWEB)

    Cubillos, G. I.; Olaya, J. J. [Universidad Nacional de Colombia, Av. Carrera 30 No. 45-03, 11321 Bogota (Colombia); Bethencourt, M. [Universidad de Cadiz, Campus de Excelencia Internacional del Mar, Av. Republica de Saharaui, E-11510 Puerto Real, Cadiz (Spain); Cifredo, G.; Blanco, G., E-mail: gcubillos@unal.edu.co [Universidad de Cadiz, Facultad de Ciencias, Campus Rio San Pedro, 11510 Puerto Real, Cadiz (Spain)

    2014-07-01

    Thin films of zirconium oxynitride were deposited on stainless steel 316l and characterized through ultrasonic spray pyrolysis-nitriding (Ups-N). Initially, thin films of ZrO{sub 2} are deposited using ultrasonic spray pyrolysis, and later ZrO{sub 2} films were nitrided in a NH{sub 3} atmosphere. We analyzed the effect of some variables, such as substrate temperature, flow ratio, and time of the production of coatings and their influence on the structure of the films. The characterization was carried out using X-ray diffraction (XRD) spectroscopy, X-ray photoelectron (XP S) and scanning electron microscopy (Sem). Films that were grown using the Ups method exhibited a tetragonal zirconia polycrystalline structure with preferential orientation in plane. These films, after being nitrided in an atmosphere of anhydrous ammonia at 1023 K, go through two processes: a phase transition from tetragonal to monoclinic, and later the formation of zirconium oxynitride rhombohedral ZrO{sub x}N{sub y}. (Author)

  9. Tribological performance evidence on ternary and quaternary nitride coatings applied for industrial steel

    Energy Technology Data Exchange (ETDEWEB)

    Caicedo, J. C.; Aguilar, Y. [Universidad del Valle, School of Materials Engineering, Ciudad Universitaria Melendez, Calle 13 No. 100-00, Edif. 320, A. A. 25360 Cali (Colombia); Aperador, W., E-mail: jcaicedoangulo1@gmail.com [Universidad Militar Nueva Granada, Department of Engineering, Carrera 11 No. 101-80, 6343200 Bogota D. C. (Colombia)

    2013-08-01

    A diagnostic of mechanical and tribological behavior in ternary Ti-C-N and quaternary Ti-Nb-C-N films deposited onto Si (100) and 4140 steel substrates by r.f. magnetron sputtering process varying negative bias voltage from 0 to 100 V, was done in this work. Growth parameters as power density, Ar/N{sub 2} flow rate, and substrate temperature were kept constant at the moment of the deposition. Introduction of Nb in the ternary Ti-C-N film was evaluated by X-ray diffraction analysis. Quantitative elemental concentration depth profile by glow discharge optical emission spectroscopy and the morphology via scanning electron microscopy were observed for the layers before the tests. Mechanical and tribological properties for both coatings were obtained by mean of nano indentation measurements through load versus displacement method, and scratch test using the critical load criterion, respectively. The failure modes from scratch test were observed via optical microscopy. X-ray diffraction results show as the amount of Nb is increased into the quaternary phase, the preferred orientation change in the film dur to the modification in the strain and lattice parameter. Energy dispersive X-ray results from previous work show the Ti CN and TiNbCN layers were stoichiometric. Nano indentation results reaching the elastic-plastic behavior of the Ti CN and Ti CN films with inclusion of Nb (TiNbCN), indicate not only the hardness and elastic modulus but also the critical load for the adhesive failure increase when increasing r.f negative bias voltage. An improvement of hardness and critical load around 60% and 28% for Ti CN as well as 26% and 31% for TiNbCN, respectively, was associated to an increasing in the r.f negative bias voltage from 0 to - 100 V. (Author)

  10. Processing, structure and tribological property relations of ternary Zn-Ti-O and quaternary Zn-Ti-Zr-O nanocrystalline coatings

    Science.gov (United States)

    Ageh, Victor

    Conventional liquid lubricants are faced with limitations under extreme cyclic operating conditions, such as in applications that require lubrication when changing from atmospheric pressure to ultrahigh vacuum and ambient air to dry nitrogen (e.g., satellite components), and room to elevated (>500°C) temperatures (e.g., aerospace bearings). Alternatively, solid lubricant coatings can be used in conditions where synthetic liquid lubricants and greases are not applicable; however, individual solid lubricant phases usually perform best only for a limited range of operating conditions. Therefore, solid lubricants that can adequately perform over a wider range of environmental conditions are needed, especially during thermal cycling with temperatures exceeding 500°C. One potential material class investigated in this dissertation is lubricious oxides, because unlike other solid lubricant coatings they are typically thermodynamically stable in air and at elevated temperatures. While past studies have been focused on binary metal oxide coatings, such as ZnO, there have been very few ternary oxide and no reported quaternary oxide investigations. The premise behind the addition of the third and fourth refractory metals Ti and Zr is to increase the number of hard and wear resistant phases while maintaining solid lubrication with ZnO. Therefore, the major focus of this dissertation is to investigate the processing-structuretribological property relations of composite ZnO, TiO2 and ZrO2 phases that form ternary (ZnTi)xOy and quaternary (ZnTiZr) xOy nanocrystalline coatings. The coatings were processed by atomic layer deposition (ALD) using a selective variation of ALD parameters. The growth structure and chemical composition of as-deposited and ex situ annealed ternary and quaternary oxide coatings were studied by combined x-ray diffraction/focused ion beam microscopy/cross-sectional transmission electron microscopy, and x-ray photoelectron spectroscopy/Auger electron

  11. Corrosion Resistance Behavior of Single-Layer Cathodic Arc PVD Nitride-Base Coatings in 1M HCl and 3.5 pct NaCl Solutions

    Science.gov (United States)

    Adesina, Akeem Yusuf; Gasem, Zuhair M.; Madhan Kumar, Arumugam

    2017-04-01

    The electrochemical behavior of single-layer TiN, CrN, CrAlN, and TiAlN coatings on 304 stainless steel substrate, deposited using state-of-the-art and industrial size cathodic arc PVD machine, were evaluated in 1M HCl and 3.5 pct NaCl solutions. The corrosion behavior of the blank and coated substrates was analyzed by electrochemical impedance spectroscopy (EIS), linear polarization resistance, and potentiodynamic polarization. Bond-coat layers of pure-Ti, pure-Cr, alloyed-CrAl, and alloyed-TiAl for TiN, CrN, CrAlN, and TiAlN coatings were, respectively, first deposited for improved coating adhesion before the actual coating. The average coating thickness was about 1.80 µm. Results showed that the corrosion potentials ( E corr) of the coated substrates were shifted to more noble values which indicated improvement of the coated substrate resistance to corrosion susceptibility. The corrosion current densities were lower for all coated substrates as compared to the blank substrate. Similarly, EIS parameters showed that these coatings possessed improved resistance to defects and pores in similar solution compared to the same nitride coatings developed by magnetron sputtering. The charge transfer resistance ( R ct) can be ranked in the following order: TiAlN > CrN > TiN > CrAlN in both media except in NaCl solution where R ct of TiN is lowest. While the pore resistance ( R po) followed the order: CrAlN > CrN > TiAlN > TiN in HCl solution and TiAlN > CrN > CrAlN > TiN in NaCl solution. It is found that TiAlN coating has the highest protective efficiencies of 79 and 99 pct in 1M HCl and 3.5 pct NaCl, respectively. SEM analysis of the corroded substrates in both media was also presented.

  12. Corrosion Resistance Behavior of Single-Layer Cathodic Arc PVD Nitride-Base Coatings in 1M HCl and 3.5 pct NaCl Solutions

    Science.gov (United States)

    Adesina, Akeem Yusuf; Gasem, Zuhair M.; Madhan Kumar, Arumugam

    2017-01-01

    The electrochemical behavior of single-layer TiN, CrN, CrAlN, and TiAlN coatings on 304 stainless steel substrate, deposited using state-of-the-art and industrial size cathodic arc PVD machine, were evaluated in 1M HCl and 3.5 pct NaCl solutions. The corrosion behavior of the blank and coated substrates was analyzed by electrochemical impedance spectroscopy (EIS), linear polarization resistance, and potentiodynamic polarization. Bond-coat layers of pure-Ti, pure-Cr, alloyed-CrAl, and alloyed-TiAl for TiN, CrN, CrAlN, and TiAlN coatings were, respectively, first deposited for improved coating adhesion before the actual coating. The average coating thickness was about 1.80 µm. Results showed that the corrosion potentials (E corr) of the coated substrates were shifted to more noble values which indicated improvement of the coated substrate resistance to corrosion susceptibility. The corrosion current densities were lower for all coated substrates as compared to the blank substrate. Similarly, EIS parameters showed that these coatings possessed improved resistance to defects and pores in similar solution compared to the same nitride coatings developed by magnetron sputtering. The charge transfer resistance (R ct) can be ranked in the following order: TiAlN > CrN > TiN > CrAlN in both media except in NaCl solution where R ct of TiN is lowest. While the pore resistance (R po) followed the order: CrAlN > CrN > TiAlN > TiN in HCl solution and TiAlN > CrN > CrAlN > TiN in NaCl solution. It is found that TiAlN coating has the highest protective efficiencies of 79 and 99 pct in 1M HCl and 3.5 pct NaCl, respectively. SEM analysis of the corroded substrates in both media was also presented.

  13. Enhancement of the Luminescence of ZnO Nanorod Arrays by SILAR Coating with a CdS Nanocrystalline Shell Layer

    Science.gov (United States)

    Krishnaveni, M.; Devadason, Suganthi

    2015-02-01

    ZnO/CdS core/shell-type nanorod arrays (NRAs) have been synthesized by a simple chemical method. The thickness of the CdS shell layers was controlled by varying the number of successive ionic layer adsorption and reaction cycles. X-ray diffraction analysis revealed the ZnO had a hexagonal crystal structure and the CdS had a cubic crystal structure. High-resolution transmission electron microscopy revealed that a highly conforming CdS shell layer ˜5 nm thick had been deposited on the ZnO nanorods. High-resolution scanning electron microscopy revealed the presence of hexagonal ZnO nanorods entirely coated with a nanocrystalline CdS shell. The ultraviolet-visible-near infrared absorption spectra of the films were red shifted and the calculated optical energy band gap decreased from 3.25 to 2.46 eV with progressive increase of CdS shell layer thickness. Photoluminescence spectra revealed enhancement of the near-band-edge emission centered at 380 nm of the ZnO NRAs after coating with the CdS shell layer. The observed shift in deep level emissions from yellow to green in the ZnO/CdS core/shell heterostructures has been explained. The measured electrical resistivity of bare ZnO and ZnO/CdS core/shell NRAs was 5.43 × 10-3 Ω cm and 1.25 × 10-3 Ω cm, respectively, when the films were illuminated with visible light.

  14. Surface structure and photoemission studies of nanocrystalline TiO{sub 2} layer/ITO coated glass interface

    Energy Technology Data Exchange (ETDEWEB)

    Taleatu, Bidini Alade, E-mail: bdntaleatu@gmail.com [Department of Physics and Engineering Physics, Obafemi Awolowo University, Ile-Ife (Nigeria); School of Chemistry and Physics, University of KwaZulu-Natal, P Bag X01, Scottsville, 3209 Pietermaritzburg (South Africa); Omotoso, Ezekiel [Department of Physics and Engineering Physics, Obafemi Awolowo University, Ile-Ife (Nigeria); Mola, Genene Tessema [School of Chemistry and Physics, University of KwaZulu-Natal, P Bag X01, Scottsville, 3209 Pietermaritzburg (South Africa)

    2016-02-15

    Highlights: • Titanium oxide thin film was grown on ITO glass substrate by electrodeposition technique. • The samples were charaterized and analysed by some surface studying facilities. • Photoemission studies were carried out befor and after annealing to understand possible interaction between the TiO{sub 2} layer and substrate as a result of postdeposition heat treatment. - Abstract: Room temperature growth of nanocrystalline TiO{sub 2} thin film was carried out by two-electrode cell. The film was characterized by surface probing techniques. Morphological studies revealed that film's grains are evenly distributed across substrate surface. Average height of grains distribution is below 64 nm. Post-deposition annealing aided film's particles’ orientation in a structure that resulted in compact layer. Average crystallite size was estimated as 19.5 nm. Quality and chemical states of film composition were observed by core level photoemission studies. From XPS studies, small shift (∼0.11 eV) observed in binding energy position of Ti 2p{sub 3/2} corroborated oxidation states of titanium species found in TiO{sub 2} structure. Peak broadening and formation of In−O−Sn linkage at oxygen valence band indicated interactions between substrate's atoms due to annealing. Apart from substrate's atoms interaction, chemical state of Ti profile remained stable implying no major chemical interaction between ITO atoms and film components. This study demonstrated TiO{sub 2} as a recipe for stable barrier layer capable of hindering charge trapping in nanostructured photonic devices.

  15. The structure and mechanical properties of multilayer nanocrystalline TiN/ZrN coatings obtained by vacuum-arc deposition

    Directory of Open Access Journals (Sweden)

    A.V. Demchyshyn

    2007-12-01

    Full Text Available TiN/ZrN multilayered condensates on BK-8 carbide tips substrates (62 HRC were produced by the vacuumarc deposition technique, using Ti and Zr plasma flows in reactive nitrogen gas medium with working pressure of 6.6·10–1 Pa. The TiN/ZrN multilayered condensates consist of TiN and ZrN sublayers, which have a thickness of ~100 nm, controlled by the processing parameters of the used deposition technique. The obtained coatings have hardness of 45 GPa and Young’s modulus of 320 GPa. The obtained results show that mechanical properties of such multilayered composites are considerably improved in comparison to those for the single-component coatings, TiN and ZrN. The dependence of hardness and Young’s modulus of the composites on sublayer thickness within a range of 100 nm was determined. The investigated structure and improved mechanical properties of the TiN/ZrN multilayered condensates would be very good platform for finding their industrial application, such as hard coatings with different purposes.

  16. Nanocrystalline sol-gel TiO{sub 2}-SnO{sub 2} coatings: Preparation, characterization and photo-catalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Kaleji, Behzad Koozegar [Department of Materials Engineering, Faculty of Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Sarraf-Mamoory, Rasoul, E-mail: rsarrafm@modares.ac.ir [Department of Materials Engineering, Faculty of Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer SnO{sub 2} additive enhanced significantly photo-catalytic properties of TiO{sub 2} based thin film for remove of organic compounds. Black-Right-Pointing-Pointer Structural and optical properties are dependent on dopant concentration. Black-Right-Pointing-Pointer TiO{sub 2}-SnO{sub 2} nanocrystalline thin film is promising for photocatalytic properties in visible light. -- Abstract: In this study, preparation of SnO{sub 2} (0-30 mol% SnO{sub 2})-TiO{sub 2} dip-coated thin films on glazed porcelain substrates via sol-gel process has been investigated. The effects of SnO{sub 2} on the structural, optical, and photo-catalytic properties of applied thin films have been studied by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. Surface topography and surface chemical state of thin films were examined by atomic force microscopy and X-ray photoelectron spectroscopy. XRD patterns showed an increase in peak intensities of the rutile crystalline phase by increasing the SnO{sub 2} content. The prepared Sn doped TiO{sub 2} photo-catalyst films showed optical absorption in the visible light area exhibited excellent photo-catalytic ability for the degradation of methylene blue under visible light irradiation. Best photo-catalytic activity of Sn doped TiO{sub 2} thin films was measured in the TiO{sub 2}-15 mol% SnO{sub 2} sample by the Sn{sup 4+} dopants presented substitution Ti{sup 4+} into the lattice of TiO{sub 2} increasing the surface oxygen vacancies and the surface hydroxyl groups.

  17. [Corrosion resistance and wear resistance of Ni-Cr alloy after coating titanium nitride (TiN) in oral containing fluorine environment].

    Science.gov (United States)

    Weng, Wei-Min; Yu, Wei-Qiang; Shan, Wei-Lan; Zhang, Fu-Qiang

    2010-12-01

    The aim of this study was to evaluate the corrosion resistance and wear resistance of Ni-Cr alloy after coating titanium nitride (TiN) in oral containing fluorine environment. Physical vapor deposition was established to coat titanium nitride (TiN) on the surface of dental cast Ni-Cr alloy to form TiN/Ni-Cr compound. Both Ni-Cr alloy and TiN/Ni-Cr compound were exposed to 37 degrees centigrade, artificial saliva containing 0.24% NaF. The polarization curves of the specimens were measured by PARSTAT 2273 electrochemical station to investigate its corrosion resistance. Vicker's hardness was measured by HXD-1000TMC/LCD micro-hardness tester to investigate its wear resistance. Statistical analysis was performed by SAS 8.2 software package for Student's t methods. The corrosion potential of Ni-Cr alloy was -362.407 mV, the corrosion current density was 1.568μAcm(-2),the blunt-breaking potential was 426 mV bofor TiN coating. The corrosion potential of TiN/Ni-Cr compound was -268.638 mV, the corrosion current density was 0.114μAcm(-2),the blunt-breaking potential was 1142 mV after TiN coating. Polarization curves showed TiN/Ni-Cr compound improved the corrosion potential and blunt-breaking potential, decreased the corrosion current density. The Vicker's hardness of Ni-Cr alloy was 519.75±27.27 before TiN coating, the Vicker's hardness of TiN/Ni-Cr compound was 803.24±24.64, the D-value between them was 283.49±39.34. The difference of Vicker's harnesses between Ni-Cr alloy and TiN/Ni-Cr compound had significant (Pcoating can improve the corrosion resistant to F-and the surface hardness of Ni-Cr alloy. Supported by Research Fund of Science and Technology Commission of Shanghai Municipality (Grant No.08DZ2271100), Shanghai Leading Academic Discipline Project (Grant No.S30206 ) and Research Fund of Health Bureau of Shanghai Municipality (Grant No.2009074).

  18. Low pressure growth of cubic boron nitride films

    Science.gov (United States)

    Ong, Tiong P. (Inventor); Shing, Yuh-Han (Inventor)

    1997-01-01

    A method for forming thin films of cubic boron nitride on substrates at low pressures and temperatures. A substrate is first coated with polycrystalline diamond to provide a uniform surface upon which cubic boron nitride can be deposited by chemical vapor deposition. The cubic boron nitride film is useful as a substitute for diamond coatings for a variety of applications in which diamond is not suitable. any tetragonal or hexagonal boron nitride. The cubic boron nitride produced in accordance with the preceding example is particularly well-suited for use as a coating for ultra hard tool bits and abrasives, especially those intended to use in cutting or otherwise fabricating iron.

  19. Structure-property relations for silicon nitride matrix composites reinforced with pyrolytic carbon pre-coated Hi-Nicalon fibers

    NARCIS (Netherlands)

    Kooi, B.J.; Hosson, J.Th.M. De; Olivier, C.; Veyret, J.B.

    1999-01-01

    Si3N4 matrix composites reinforced with pyrolytic carbon pre-coated Hi-Nicalon (SiC) fibers, were studied using tensile testing and transmission electron microscopy. Three types of samples were evaluated all with a nominal coating thickness of 200 nm. The composites were densified by hot pressing at

  20. Structure-property relations for silicon nitride matrix composites reinforced with pyrolytic carbon pre-coated Hi-Nicalon fibers

    NARCIS (Netherlands)

    Kooi, B.J.; Hosson, J.Th.M. De; Olivier, C.; Veyret, J.B.

    1999-01-01

    Si3N4 matrix composites reinforced with pyrolytic carbon pre-coated Hi-Nicalon (SiC) fibers, were studied using tensile testing and transmission electron microscopy. Three types of samples were evaluated all with a nominal coating thickness of 200 nm. The composites were densified by hot pressing at

  1. A novel hohlraum with ultrathin depleted-uranium-nitride coating layer for low hard x-ray emission and high radiation temperature

    CERN Document Server

    Guo, Liang; Xing, Peifeng; Li, Sanwei; Yi, Taimin; Kuang, Longyu; Li, Zhichao; Li, Renguo; Wu, Zheqing; Jing, Longfei; Zhang, Wenhai; Zhan, Xiayu; Yang, Dong; Jiang, Bobi; Yang, Jiamin; Liu, Shenye; Jiang, Shaoen; Li, Yongsheng; Liu, Jie; Huo, Wenyi; Lan, Ke

    2014-01-01

    An ultra-thin layer of uranium nitrides (UN) has been coated on the inner surface of the depleted uranium hohlraum (DUH), which has been proved by our experiment can prevent the oxidization of Uranium (U) effectively. Comparative experiments between the novel depleted uranium hohlraum and pure golden (Au) hohlraum are implemented on Shenguang III prototype laser facility. Under the laser intensity of 6*10^14 W/cm2, we observe that, the hard x-ray (> 1.8 keV) fraction of this uranium hohlraum decreases by 61% and the peak intensity of total x-ray flux (0.1 keV ~ 5 keV) increases by 5%. Two dimensional radiation hydrodynamic code LARED are exploited to interpret the above observations. Our result for the first time indicates the advantage of the UN-coated DUH in generating the uniform x-ray field with a quasi Planckian spectrum and thus has important implications in optimizing the ignition hohlraum design.

  2. Machining Performance of Sputter-Deposited (Al0.34Cr0.22Nb0.11Si0.11Ti0.2250N50 High-Entropy Nitride Coatings

    Directory of Open Access Journals (Sweden)

    Wan-Jui Shen

    2015-07-01

    Full Text Available (Al0.34Cr0.22Nb0.11Si0.11Ti0.2250N50 high-entropy nitride coatings prepared by reactive magnetron sputtering have been proved to have high hardness and superior oxidation resistance. Their thermal stability, adhesion strength, and cutting performance were investigated in this study. Hardness of the coating is 36 GPa, which only decreases slightly to 33 GPa after 900 °C annealing either in air or in vacuum for 2 h. No significant change in phase and microstructure were detected after annealing at 1000 °C. Rockwell C indentation and scratch tests shows that Ti interlayer provides a good adhesion between the nitride film and WC/Co substrates. In various milling tests, inserts coated with (Al0.34Cr0.22Nb0.11Si0.11Ti0.2250N50 have evidently smaller flank wear depth than commercial inserts coated with TiN and TiAlN, even with their smaller thickness. Therefore, the (Al0.34Cr0.22Nb0.11Si0.11Ti0.2250N50 coating has great potential in hard coating applications.

  3. Investigation of interactions between poly-L-lysine-coated boron nitride nanotubes and C2C12 cells: up-take, cytocompatibility, and differentiation

    Directory of Open Access Journals (Sweden)

    G Ciofani

    2010-04-01

    Full Text Available G Ciofani1, L Ricotti1, S Danti2,3, S Moscato4, C Nesti2, D D’Alessandro2,4, D Dinucci5, F Chiellini5, A Pietrabissa3, M Petrini2,3, A Menciassi1,61Scuola Superiore Sant’Anna, Pisa, Italy; 2CUCCS-RRMR, Center for the Clinical Use of Stem Cells – Regional Network of Regenerative Medicine, 3Department of Oncology, Transplants and Advanced Technologies, 4Department of Human Morphology and Applied Biology, University of Pisa, Pisa, Italy; 5Laboratory of Bioactive Polymeric Materials for Biomedical and Environmental Applications (BIOlab, UdR INSTM, Department of Chemistry and Industrial Chemistry, University of Pisa, San Piero a Grado, Italy; 6Italian Institute of Technology, Genova, ItalyAbstract: Boron nitride nanotubes (BNNTs have generated considerable interest within the scientific community by virtue of their unique physical properties, which can be exploited in the biomedical field. In the present in vitro study, we investigated the interactions of poly-L-lysine-coated BNNTs with C2C12 cells, as a model of muscle cells, in terms of cytocompatibility and BNNT internalization. The latter was performed using both confocal and transmission electron microscopy. Finally, we investigated myoblast differentiation in the presence of BNNTs, evaluating the protein synthesis of differentiating cells, myotube formation, and expression of some constitutive myoblastic markers, such as MyoD and Cx43, by reverse transcription – polymerase chain reaction and Western blot analysis. We demonstrated that BNNTs are highly internalized by C2C12 cells, with neither adversely affecting C2C12 myoblast viability nor significantly interfering with myotube formation.Keywords: boron nitride nanotubes, C2C12 cells, cytocompatibility, up-take, differentiation, MyoD, connexin 43

  4. Investigation of wear and tool life of coated carbide and cubic boron nitride cutting tools in high speed milling

    Directory of Open Access Journals (Sweden)

    Pawel Twardowski

    2015-06-01

    Full Text Available The objective of the investigation was analysis of the wear of milling cutters made of sintered carbide and of boron nitride. The article presents the life period of the cutting edges and describes industrial conditions of the applicability of tools made of the materials under investigation. Tests have been performed on modern toroidal and ball-end mill cutters. The study has been performed within a production facility in the technology of high speed machining of 55NiCrMoV6 and X153CrMoV12 hardened steel. The analysed cutting speed is a parameter which significantly influences the intensity of heat generated in the cutting zone. Due to the wear characteristics, two areas of applicability of the analysed tools have been distinguished. For vc  ≤ 300 m/min, sintered carbide edges are recommended; for vc  > 500 m/min, boron nitride edges. For 300 ≤ vc  ≤ 500 m/min, a transition area has been observed. It has been proved that the application of sintered carbide edges is not economically justified above certain cutting speed.

  5. Structural and corrosion characterization of hydroxyapatite/zirconium nitride-coated AZ91 magnesium alloy by ion beam sputtering

    Science.gov (United States)

    Kiahosseini, Seyed Rahim; Afshar, Abdollah; Mojtahedzadeh Larijani, Majid; Yousefpour, Mardali

    2017-04-01

    The adhesion of hydroxyapatite (HA) as a coating for the AZ91 magnesium alloy substrate can be improved by using the sputtering method and an intermediate layer, such as ZrN. In this study, HA coatings were applied on ZrN intermediate layers at a temperature of 300 °C for 180, 240, 300, 360, and 420 min by ion beam sputtering. A profilometer device was used to study the HA coating thickness, which changed from 2 μm for the 180-min deposition to 4.7 μm for 420-min deposition. The grazing incidence X-ray diffraction analysis method and the Williamson-Hall analysis were used for structural investigation. As the deposition time increased, the crystalline size increased from 50 nm to 690 nm. However, given sufficient time for stress relief on the coating structure, the lattice strain values were close to zero. Energy-dispersive X-ray spectroscopy results showed that the Ca/P ratio ranged from 1.73 to 1.81. The external indentation method was used to evaluate the coating adhesion to the substrate. The slope of curve for applied force changes versus the radius of cracks in the coating (dP/dr) varied in the range of 0.2-0.07 by the deposition time, indicating that the adhesion increased with the increase in coating thickness. The potentiodynamic polarization technique was used to study the corrosion behavior. With increasing deposition time, the corrosion potential of samples did not show a significant change, and the corrosion potential of all samples (coated and uncoated substrates) was more positive than approximately 55 mV. When the deposition time increased to 360 min, the corrosion current density decreased from 5.5 μA/cm2 to 0.33 μA/cm2. After 420 min of deposition, the current density increased to 8.2 μA/cm2. Scanning electron microscopy images of the HA surface layer after 420 min clearly showed cracks on the coating surface, which led to the increase in corrosion current density.

  6. Study on Macro-morphology of Hard whirling Chips with PCBN Cutting Tools Coated with Chromium Aluminum Nitride%氮化铬铝涂层PCBN刀具旋风硬铣切屑宏观特征研究

    Institute of Scientific and Technical Information of China (English)

    朱红雨; 李迎

    2011-01-01

    氮化铬铝具有比氮化钛铝更高的硬度和抗氧化性,能否作为PCBN刀具的涂层需要进行试验研究验证.通过对氮化铬铝涂层PCBN刀具在硬态旋风铣削淬硬钢GCr15平均硬度为63.5HRC)加工中,选用不同的切削参数、冷却方式和刀具个数的研究,从而得出氮化铬铝涂层PCBN刀具旋风硬铣加工的特点和应用范围,对涂层刀具的研究和切屑预报研究提供了依据.%Chromium Aluminum Nitride has much more hardness and oxidation resistance than Titanium Aluminum Nitride. This article studied on cutting tool wear, surface processing quality of work piece and macro-morphology of chips during the hard whirling machining on hardened steel GCrl5 with average hardness at 63. 5HRC through PCBN cutting tools coated with Chromium Aluminum Nitride. Through testing with different cutting parameters, different cooling mode and different cutting tool numbers, this article illustrated characters and application scope of hard whirling machining with PCBN cutting tools coated with Chromium Aluminum Nitride and provided a basis for research on cutting tool coating or research on machining forecasting through chips.

  7. Radiation Stability of Triple Coatings Based on Transition-Metal Nitrides Under Irradiation By Alpha Particles and Argon Ions

    Science.gov (United States)

    Potekaev, A. I.; Kislitsyn, S. B.; Uglov, V. V.; Klopotov, A. A.; Gorlachev, I. D.; Klopotov, V. D.; Grinkevich, L. S.

    2016-05-01

    The data on the influence of irradiation of (Ti, Cr)N1-x coatings by helium and argon ions on their surface structure are presented. The (Ti, Cr)N1-x coatings 50-300 nm in thickness were formed on carbon steel substrates by vacuum-arc deposition. Irradiation of the coated specimens was performed in a DC-60 heavy-ion accelerator by low-energy 4He+1, 4He+2 and 40Ar5+ ions and high-energy 40Ar5+ ions up to the fluence 1.0·1017 ion/cm2 at the irradiation temperature not higher than 150°C. It is shown that irradiation of the (Ti, Cr)N1-x coating surface by 4He+1, 4He+2 and 40Ar5+ ions with the energy 20 keV/charge does not give rise to any noticeable structural changes nor any surface blistering, while its irradiation by 40Ar5+ ions with the energy 1.50 MeV/amu causes blistering.

  8. Constructing Novel Fiber Reinforced Plastic (FRP Composites through a Biomimetic Approach: Connecting Glass Fiber with Nanosized Boron Nitride by Polydopamine Coating

    Directory of Open Access Journals (Sweden)

    XueMei Wen

    2013-01-01

    Full Text Available A biomimetic method was developed to construct novel fiber reinforced plastic (FRP composites. By mimicking mussel adhesive proteins, a monolayer of polydopamine was coated on glass fiber (GF surface. The polydopamine-treated GF (D-GF adsorbed boron nitride (BN nanoparticles, while obtaining micronano multiscale hybrid fillers BN-D-GF. Scanning electron microscopy (SEM results showed that the strong interfacial interaction brought by the polydopamine benefits the loading amount as well as dispersion of the nano-BN on GF’s surface. The BN-D-GF was incorporated into epoxy resin to construct “FRP nanocomposites.” The morphology, dynamic mechanical and thermal characteristics of the FRP nanocomposites were analyzed. SEM morphology revealed that BN-D-GF heterogeneous dispersed in epoxy matrix. There was good adhesion between the polymer matrix and the BN-D-GF filler. The dynamic modulus and mechanical loss were studied using dynamic mechanical analysis (DMA. Compared with neat epoxy and untreated GF reinforced composites, BN-D-GF/epoxy and D-GF/epoxy systems showed improved mechanical properties. The thermal conductivity, Shore D hardness, and insulation properties were also enhanced.

  9. Nanocrystalline ceramic materials

    Science.gov (United States)

    Siegel, Richard W.; Nieman, G. William; Weertman, Julia R.

    1994-01-01

    A method for preparing a treated nanocrystalline metallic material. The method of preparation includes providing a starting nanocrystalline metallic material with a grain size less than about 35 nm, compacting the starting nanocrystalline metallic material in an inert atmosphere and annealing the compacted metallic material at a temperature less than about one-half the melting point of the metallic material.

  10. 可溶性阳极电刷镀纳米晶Ni-Fe合金镀层的退火再强化%Annealing hardening of nanocrystalline Ni-Fe alloy coatings synthesized by brush plating using soluble anode

    Institute of Scientific and Technical Information of China (English)

    戴品强; 陈晓文; 项忠楠; 许伟长

    2009-01-01

    Nanocrystalline Ni-Fe alloy coatings were synthesized by brush plating using soluble anode. Microhardness test and techniques of XRD, SEM and TEM were applied to characterize the microstructures and mechanical properties of Ni-Fe alloy coatings. The results show that the microhardness of Ni-Fe alloy coatings increases with increasing annealing temperature and reaches a peak value at 200 ℃, showing a significant hardening during annealing. With further increasing annealing temperature, the microhardness decreases gradually, but the microhardness of the coating after being annealed at 400 ℃ is still as high as that of the as-deposited sample. The abnormal grain growth is not observed during annealing of Ni-Fe alloy coatings, which indicates a better thermal stability.%采用可溶性Ni阳极电刷镀方法制备纳米晶Ni-Fe合金镀层,利用XRD、SEM、TEM、显微硬度计等测试方法分析低温退火对镀层结构和性能的影响.结果表明:纳米晶Ni-Fe合金镀层的硬度随退火温度的升高而提高,在200 ℃时达到最大值,存在明显的退火再强化;继续提高退火温度导致镀层硬度降低;400 ℃退火后的镀层硬度与镀态的接近;纳米晶Ni-Fe合金镀层退火过程没有出现晶粒异常长大,表现出比纯Ni镀层更高的热稳定性.

  11. Hard and superhard nanocomposite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Musil, J. [Univ. of West Bohemia, Plzen (Czech Republic). Dept. of Phys.

    2000-03-01

    This article reviews the development of hard coatings from a titanium nitride film through superlattice coatings to nanocomposite coatings. Significant attention is devoted to hard and superhard single layer nanocomposite coatings. A strong correlation between the hardness and structure of nanocomposite coatings is discussed in detail. Trends in development of hard nanocomposite coatings are also outlined. (orig.)

  12. 牙科钴铬合金表面镀氮化锆层后的耐磨性研究%Study on wear resistance of zirconium nitride coating on dental Co-Cr alloy

    Institute of Scientific and Technical Information of China (English)

    桑卓; 付玉; 毛艳; 古育娣; 蹇航

    2016-01-01

    ObjectiveTo provide a reference basics for the substrate surface treatment according to oral clinic requirements, the wear resistance of zirconium nitride coating on dental Co-Cr alloy was evaluated in this study.Methods Using the magnetron sputtering deposition technology, under a constant heating temperature (200℃),①constant sputtering power (100 w) with different nitrogen partial pressure (25%, 35%, 45%), and② constant nitrogen partial pressure (35%) with different supttering power (50w, 100w, 200w), the zirconium nitride coat-ing was deposited on the surface of dental Co-Cr ally. The wear resistances of two dental Co-Cr alloys with and without zirconium nitride coating were assessed and compared by wear resistance tests.Results The weight loss of test specimens with zirconium nitride coating was significantly less than the uncoated specimens (P<0.05). Under deposition conditions of constant sputtering power and substrate temperature, the weight loss reached the minimum when the nitrogen partial pressure was 35%. Under deposition conditions of constant nitrogen partial pressure and substrate temperature, the weight loss of dental Co-Cr alloy with coatings reached the lowest value when the power was 50w.Conclusion Under the suitable technological conditions, zirconium nitride coatings with excellent properties can be prepared on dental casting Co-Cr alloy by magnetron sputtering coating technology.%目的:评价钴铬(Co-Cr)合金表面经镀氮化锆膜后的耐磨损性,为口腔临床要求的基底表面处理方式提供参考依据。方法运用磁控溅射镀膜技术,设定基体加热温度200℃恒定,分别在①功率为100w、氮气分压选择为25%、35%、45%以及②氮气分压35%,功率为50w、100w、200w的条件下,在Co-Cr合金表面沉积氮化锆涂层,采用磨损试验机测试并比较氮化锆涂层和未镀膜之间的耐磨性能。结果镀氮化锆试件的失重量显著小于未镀膜试件(P<0.05).其中

  13. Nanocrystalline ceramic materials

    Science.gov (United States)

    Siegel, R.W.; Nieman, G.W.; Weertman, J.R.

    1994-06-14

    A method is disclosed for preparing a treated nanocrystalline metallic material. The method of preparation includes providing a starting nanocrystalline metallic material with a grain size less than about 35 nm, compacting the starting nanocrystalline metallic material in an inert atmosphere and annealing the compacted metallic material at a temperature less than about one-half the melting point of the metallic material. 19 figs.

  14. Microstructure and Corrosion Behavior of Ni-Alloy/CrN Nanolayered Coatings

    Directory of Open Access Journals (Sweden)

    Hao-Hsiang Huang

    2011-01-01

    Full Text Available The Ni-alloy/CrN nanolayered coatings, Ni-Al/CrN and Ni-P/CrN, were deposited on (100 silicon wafer and AISI 420 stainless steel substrates by dual-gun sputtering technique. The influences of the layer microstructure on corrosion behavior of the nanolayered thin films were investigated. The bilayer thickness was controlled approximately 10 nm with a total coating thickness of 1m. The single-layer Ni-alloy and CrN coatings deposited at 350∘C were also evaluated for comparison. Through phase identification, phases of Ni-P and Ni-Al compounds were observed in the single Ni-alloy layers. On the other hand, the nanolayered Ni-P/CrN and Ni-Al/CrN coatings showed an amorphous/nanocrystalline microstructure. The precipitation of Ni-Al and Ni-P intermetallic compounds was suppressed by the nanolayered configuration of Ni-alloy/CrN coatings. Through Tafel analysis, the corr and corr values ranged from –0.64 to –0.33 V and 1.42×10−5 to 1.14×10−6 A/cm2, respectively, were deduced for various coating assemblies. The corrosion mechanisms and related behaviors of the coatings were compared. The coatings with a nanolayered Ni-alloy/CrN configuration exhibited a superior corrosion resistance to single-layer alloy or nitride coatings.

  15. Nano-structured titanium and aluminium nitride coatings: Study by grazing incidence X-ray diffraction and X-ray absorption and anomalous diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Tuilier, M.-H., E-mail: marie-helene.tuilier@uha.fr [Universite de Haute Alsace (UHA), Laboratoire Physique et Mecanique Textile (LPMT), EA 4365 -conventionnee au CNRS, Equipe PPMR, F-68093 Mulhouse (France); Pac, M.-J. [Universite de Haute Alsace (UHA), Laboratoire Physique et Mecanique Textile (LPMT), EA 4365 - conventionnee au CNRS, Equipe PPMR, F-68093 Mulhouse (France); Anokhin, D.V. [Universite de Haute Alsace (UHA), CNRS, Institut de Science des Materiaux de Mulhouse (IS2M), LRC 7228, F-68093 Mulhouse (France); Moscow State University, Faculty of Fundamental Physical and Chemical Engineering, 119991, Moscow, GSP-1, 1-51 Leninskie Gory (Russian Federation); Ivanov, D.A. [Universite de Haute Alsace (UHA), CNRS, Institut de Science des Materiaux de Mulhouse (IS2M), LRC 7228, F-68093 Mulhouse (France); Rousselot, C. [Universite de Franche-Comte, FEMTO-ST (UMR CNRS 6174), F-25211 Montbeliard (France); Thiaudiere, D. [Synchrotron Soleil, Saint Aubin, F-91192 Gif sur Yvette (France)

    2012-12-30

    Titanium and aluminium nitride thin films, Ti{sub 1-x}Al{sub x}N (x = 0, x = 0.5, x = 0.68), deposited by reactive magnetron sputtering on silicon substrates are investigated by combining two different X-ray diffraction experiments carried out using synchrotron radiation. Grazing-incidence X-ray diffraction and Ti K-edge diffraction anomalous near edge structure spectroscopy provide information on the micro- and nano-structure of the films respectively, which play a crucial role in the functionality of coatings. The spectroscopic data of Ti{sub 0.50}Al{sub 0.50}N film show that Ti atoms in crystallized domains and grain boundaries are all in octahedral cubic local order, but their growth mode is quite different. It is found that the crystallized part of the Ti{sub 0.50}Al{sub 0.50}N film has a single-crystalline nature, whereas the TiN one presents a fibrillar microstructure. For Ti{sub 0.32}Al{sub 0.68}N film, grazing-incidence X-ray diffraction provides information on the uniaxial texture along the [001] direction of the hexagonal lattice. A sharp Ti K pre-edge peak is observed in diffraction anomalous near edge spectrum that definitely shows that Ti atoms are incorporated in the hexagonal lattice of those fibrillar domains. Moreover, the difference observed between Ti K-edge diffraction anomalous and X-ray absorption pre-edge regions proves that a significant part of Ti atoms is located in nanocrystallites with cubic symmetry outside of the crystallized domains. - Highlights: Black-Right-Pointing-Pointer We study nano and micro-structures of TiN, Ti{sub 0.50}Al{sub 0.50}N and Ti{sub 0.32}Al{sub 0.68}N films. Black-Right-Pointing-Pointer Anomalous diffraction solves the crystallized part regardless of grain boundaries. Black-Right-Pointing-Pointer TiN microstructure is fibrillar, Ti{sub 0.5}Al{sub 0.5}N presents single crystalline domains. Black-Right-Pointing-Pointer For Ti{sub 0.32}Al{sub 0.68}N, Ti atoms are located in nanocrystallites with cubic symmetry

  16. Distinctive glial and neuronal interfacing on nanocrystalline diamond.

    Directory of Open Access Journals (Sweden)

    Amel Bendali

    Full Text Available Direct electrode/neuron interfacing is a key challenge to achieve high resolution of neuronal stimulation required for visual prostheses. Neuronal interfacing on biomaterials commonly requires the presence of glial cells and/or protein coating. Nanocrystalline diamond is a highly mechanically stable biomaterial with a remarkably large potential window for the electrical stimulation of tissues. Using adult retinal cell cultures from rats, we found that glial cells and retinal neurons grew equally well on glass and nanocrystalline diamond. The use of a protein coating increased cell survival, particularly for glial cells. However, bipolar neurons appeared to grow even in direct contact with bare diamond. We investigated whether the presence of glial cells contributed to this direct neuron/diamond interface, by using purified adult retinal ganglion cells to seed diamond and glass surfaces with and without protein coatings. Surprisingly, these fully differentiated spiking neurons survived better on nanocrystalline diamond without any protein coating. This greater survival was indicated by larger cell numbers and the presence of longer neurites. When a protein pattern was drawn on diamond, neurons did not grow preferentially on the coated area, by contrast to their behavior on a patterned glass. This study highlights the interesting biocompatibility properties of nanocrystalline diamond, allowing direct neuronal interfacing, whereas a protein coating was required for glial cell growth.

  17. Distinctive glial and neuronal interfacing on nanocrystalline diamond.

    Science.gov (United States)

    Bendali, Amel; Agnès, Charles; Meffert, Simone; Forster, Valérie; Bongrain, Alexandre; Arnault, Jean-Charles; Sahel, José-Alain; Offenhäusser, Andreas; Bergonzo, Philippe; Picaud, Serge

    2014-01-01

    Direct electrode/neuron interfacing is a key challenge to achieve high resolution of neuronal stimulation required for visual prostheses. Neuronal interfacing on biomaterials commonly requires the presence of glial cells and/or protein coating. Nanocrystalline diamond is a highly mechanically stable biomaterial with a remarkably large potential window for the electrical stimulation of tissues. Using adult retinal cell cultures from rats, we found that glial cells and retinal neurons grew equally well on glass and nanocrystalline diamond. The use of a protein coating increased cell survival, particularly for glial cells. However, bipolar neurons appeared to grow even in direct contact with bare diamond. We investigated whether the presence of glial cells contributed to this direct neuron/diamond interface, by using purified adult retinal ganglion cells to seed diamond and glass surfaces with and without protein coatings. Surprisingly, these fully differentiated spiking neurons survived better on nanocrystalline diamond without any protein coating. This greater survival was indicated by larger cell numbers and the presence of longer neurites. When a protein pattern was drawn on diamond, neurons did not grow preferentially on the coated area, by contrast to their behavior on a patterned glass. This study highlights the interesting biocompatibility properties of nanocrystalline diamond, allowing direct neuronal interfacing, whereas a protein coating was required for glial cell growth.

  18. Distinctive Glial and Neuronal Interfacing on Nanocrystalline Diamond

    Science.gov (United States)

    Bendali, Amel; Agnès, Charles; Meffert, Simone; Forster, Valérie; Bongrain, Alexandre; Arnault, Jean-Charles; Sahel, José-Alain; Offenhäusser, Andreas; Bergonzo, Philippe; Picaud, Serge

    2014-01-01

    Direct electrode/neuron interfacing is a key challenge to achieve high resolution of neuronal stimulation required for visual prostheses. Neuronal interfacing on biomaterials commonly requires the presence of glial cells and/or protein coating. Nanocrystalline diamond is a highly mechanically stable biomaterial with a remarkably large potential window for the electrical stimulation of tissues. Using adult retinal cell cultures from rats, we found that glial cells and retinal neurons grew equally well on glass and nanocrystalline diamond. The use of a protein coating increased cell survival, particularly for glial cells. However, bipolar neurons appeared to grow even in direct contact with bare diamond. We investigated whether the presence of glial cells contributed to this direct neuron/diamond interface, by using purified adult retinal ganglion cells to seed diamond and glass surfaces with and without protein coatings. Surprisingly, these fully differentiated spiking neurons survived better on nanocrystalline diamond without any protein coating. This greater survival was indicated by larger cell numbers and the presence of longer neurites. When a protein pattern was drawn on diamond, neurons did not grow preferentially on the coated area, by contrast to their behavior on a patterned glass. This study highlights the interesting biocompatibility properties of nanocrystalline diamond, allowing direct neuronal interfacing, whereas a protein coating was required for glial cell growth. PMID:24664111

  19. Deposition Technology and Microhardness of Electrochemical Deposited Ni-W Alloy Nanocrystalline

    Institute of Scientific and Technical Information of China (English)

    WUYu-cheng; SHUXia; WANGLi-ping; HUXiao-ye; WANGWen-fang; HUANGXin-min

    2004-01-01

    In this paper, a perpendicular experiment was conducted by using 4 key process parmeters, such as concentration of sodium tungstate, current density, PH value and operaftng temperature, which have obvious influence on the electrodeposition of Ni-W alloy nanocrystalline. By extreme difference analysis, the influence of multi-factors on the deposition rate and microhardness and sultace quality of the nanocrystalline alloy coatings was studied in detail. By further contrastive experiment, the influence of single-factor on the electrodeposition of Ni-W alloy nanocrystalline was also discussod, which will provide basis for the preparation of Ni-W alloy nanocrystalline.

  20. Deposition Technology and Microhardness of Electrochemical Deposited Ni-W Alloy Nanocrystalline

    Institute of Scientific and Technical Information of China (English)

    WU Yu-cheng; SHU Xia; WANG Li-ping; HU Xiao-ye; WANG Wen-fang; HUANG Xin-min

    2004-01-01

    In this paper, a perpendicular experiment was conducted by using 4 key process parameters, such as concentration of sodium tungstate, current density, PH value and operating temperature, which have obvious influence on the electrodeposition of Ni-W alloy nanocrystalline. By extreme difference analysis, the influence of multi-factors on the deposition rate and microhardness and surface quality of the nanocrystalline alloy coatings was studied in detail. By further contrastive experiment, the influence of single-factor on the electrodeposition of Ni-W alloy nanocrystalline was also discussed, which will provide basis for the preparation of Ni-W alloy nanocrystalline.

  1. Task 6.6 - Sialon Coatings for Alkali-Resistant Silicon Nitride: Semi-annual report, July 1-December 31, 1996

    Energy Technology Data Exchange (ETDEWEB)

    Nowok, J.W.

    1997-12-31

    The efficiency of a gas turbine can be improved by increasing operating temperature. Construction materials should meet both high strength requirements and hot-alkali corrosion resistance. Structural ceramics based on silicon nitride are promising candidates for high temperature engineering applications because of their high strength and good resistance to corrosion. Their performance varies significantly with the mechanical properties of boundary phases which, in turn, depend on their chemical composition, thickness of the amorphous phase, and the deformation process. To make silicon nitride ceramics tough, SiAlON ceramics were developed with controlled crystallization of the amorphous grain boundary phase. Crystallization of the grain boundary glass improves the high temperature mechanical properties of silicon nitride ceramics.

  2. Nanocrystalline sol-gel Nb{sub 2}O{sub 5} coatings. Preparation, characterisation and application to photovoltaic cell, lithium battery and eletrochromic device

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yeping

    2002-07-01

    Thick and thin films of Nb{sub 2}O{sub 5} have been prepared by the sol-gel process using cheap niobium pentachloride as precursor and a new synthesis route. The microstructure of the films was tailored by adding poly(ethylene glycol) (PEG) and carbon soot into the sol and varying the sintering temperature. The thesis describes the properties of the sols and their influence on the properties of the resulting nanocrystalline Nb{sub 2}O{sub 5} films as electrodes in dye sensitised solar cells, electrochromic devices and rechargeable lithium batteries. A solar light-to-electric conversion efficiency of Ru(II) sensitised Nb{sub 2}O{sub 5} solar cell as high as 7% under 120 W/m{sup 2} illumination was obtained. An equivalent electric circuit of the dye sensitised electrode/electrolyte interface based on the electrochemical impedance spectroscopy was modelled and found to fit all the results. The values obtained for the electric elements from the simulation of the results were found to relate material parameters to the cell performance and their influence on the cell performance are illustrated. The electrochromism and Li{sup +}-charge and discharge of the Nb{sub 2}O{sub 5} films exhibited also good performance. (orig.)

  3. Evaluation of Bone Healing on Sandblasted and Acid Etched Implants Coated with Nanocrystalline Hydroxyapatite: An In Vivo Study in Rabbit Femur

    Directory of Open Access Journals (Sweden)

    Lory Melin Svanborg

    2014-01-01

    Full Text Available This study aimed at investigating if a coating of hydroxyapatite nanocrystals would enhance bone healing over time in trabecular bone. Sandblasted and acid etched titanium implants with and without a submicron thick coat of hydroxyapatite nanocrystals (nano-HA were implanted in rabbit femur with healing times of 2, 4, and 9 weeks. Removal torque analyses and histological evaluations were performed. The torque analysis did not show any significant differences between the implants at any healing time. The control implant showed a tendency of more newly formed bone after 4 weeks of healing and significantly higher bone area values after 9 weeks of healing. According to the results from this present study, both control and nano-HA surfaces were biocompatible and osteoconductive. A submicron thick coating of hydroxyapatite nanocrystals deposited onto blasted and acid etched screw shaped titanium implants did not enhance bone healing, as compared to blasted and etched control implants when placed in trabecular bone.

  4. Superhard nano-multilayers and nanocomposite coatings

    Institute of Scientific and Technical Information of China (English)

    BAI Xiaoming; ZHENG Weitao; AN Tao

    2005-01-01

    This paper reviews the recent development of nano-multilayers and nanocomposite coatings. The hardening mechanisms and design of hard coating are discussed in details. Recent research on Ti/TiN and nitride/nitride multilayer, Ti-Si-N and Ti-Al-Si-N nanocomposite coatings is described, and the perspectives of the related research are proposed.

  5. Ion nitriding; Proceedings of the International Conference, Cleveland, OH, Sept. 15-17, 1986

    Science.gov (United States)

    Spalvins, T. (Editor)

    1987-01-01

    The present conference discusses plasma-assisted surface coating/modification processes, the applications to date of ion nitriding, the effects of nitrogen on metal surfaces, ion nitriding mechanisms in Cr, Al and Cr + Al-containing 1040 steel, ion nitriding of Al and its alloys, life enhancement for forging dies, novel anode plasma nitriding developments, and a comparative study of the pulsed and dc ion-nitriding behavior in specimens with blind holes. Also discussed are the influence of heating method on ion nitriding, surface hardening of marage steels by ion nitriding without core hardness reduction, plasma nitriding of nodular cast iron sput gears, NbN composites for superconductors, the carburization of tungsten in a glow discharge methane plasma, economic considerations concerning plasma nitriding, and the corrosion properties obtained by ion nitriding.

  6. Nitriding of Hard Fe Electrodeposition and Its Effects on Wear Resistance

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Nitriding is employed for the hard Fe electrodeposition toproduce a hard-facing and antiwear coating. It only takes 1 h for the hard Fe coating, which is much shorter than nitriding the Fe and steel. The results showed that the nitriding can increase the microhardness, wear resistance of the coating, as well as the bonding strength of the coating with the substrate. Additionally it can eliminate the brittleness, turn the internal stress of the coating from tension to compression.The wear resistance of the nitrided Fe coating is 4.6 times as high as that of Cr coating. It is simple and economic to combine hard Fe electroplating and nitriding, which is a good technology of the tribological surface modification.

  7. Creating bulk nanocrystalline metal.

    Energy Technology Data Exchange (ETDEWEB)

    Fredenburg, D. Anthony (Georgia Institute of Technology, Atlanta, GA); Saldana, Christopher J. (Purdue University, West Lafayette, IN); Gill, David D.; Hall, Aaron Christopher; Roemer, Timothy John (Ktech Corporation, Albuquerque, NM); Vogler, Tracy John; Yang, Pin

    2008-10-01

    Nanocrystalline and nanostructured materials offer unique microstructure-dependent properties that are superior to coarse-grained materials. These materials have been shown to have very high hardness, strength, and wear resistance. However, most current methods of producing nanostructured materials in weapons-relevant materials create powdered metal that must be consolidated into bulk form to be useful. Conventional consolidation methods are not appropriate due to the need to maintain the nanocrystalline structure. This research investigated new ways of creating nanocrystalline material, new methods of consolidating nanocrystalline material, and an analysis of these different methods of creation and consolidation to evaluate their applicability to mesoscale weapons applications where part features are often under 100 {micro}m wide and the material's microstructure must be very small to give homogeneous properties across the feature.

  8. Deformation in nanocrystalline metals

    OpenAIRE

    Helena Van Swygenhoven; Julia R. Weertman

    2006-01-01

    It is now possible to synthesize polycrystalline metals made up of grains that average less than 100 nm in size. Such nanocrystalline metals contain a significant volume fraction of interfacial regions separated by nearly perfect crystals. The small sizes involved limit the conventional operation of dislocation sources and thus a fundamental question arises: how do these materials deform plastically? We review the current views on deformation mechanisms in nanocrystalline, face-centered cubic...

  9. Diffusion in nanocrystalline solids

    OpenAIRE

    Chadwick, Alan V.

    2016-01-01

    Enhanced atomic migration was an early observation from experimental studies into nanocrystalline solids. This contribution presents an overview of the available diffusion data for simple metals and ionic materials in nanocrystalline form. It will be shown that enhanced diffusion can be interpreted in terms of atomic transport along the interfaces, which are comparable to grain boundaries in coarse-grained analogues. However, the method of sample preparation is seen to play a major role in...

  10. Molybdenum enhanced low-temperature deposition of crystalline silicon nitride

    Science.gov (United States)

    Lowden, Richard A.

    1994-01-01

    A process for chemical vapor deposition of crystalline silicon nitride which comprises the steps of: introducing a mixture of a silicon source, a molybdenum source, a nitrogen source, and a hydrogen source into a vessel containing a suitable substrate; and thermally decomposing the mixture to deposit onto the substrate a coating comprising crystalline silicon nitride containing a dispersion of molybdenum silicide.

  11. Microstructure, Mechanical Properties, and Two-Body Abrasive Wear Behavior of Cold-Sprayed 20 vol.% Cubic BN-NiCrAl Nanocomposite Coating

    Science.gov (United States)

    Luo, Xiao-Tao; Yang, Er-Juan; Shang, Fu-Lin; Yang, Guan-Jun; Li, Chen-Xin; Li, Chang-Jiu

    2014-10-01

    20 vol.% cubic boron nitride (cBN) dispersoid reinforced NiCrAl matrix nanocomposite coating was prepared by cold spray using mechanically alloyed nanostructured composite powders. The as-sprayed nanocomposite coating was annealed at a temperature of 750 °C to enhance the inter-particle bonding. Microstructure of spray powders and coatings was characterized. Vickers microhardness of the coatings was measured. Two-body abrasive wear behavior of the coatings was examined on a pin-on-disk test. It was found that, in mechanically alloyed composite powders, nano-sized and submicro-sized cBN particles are uniformly distributed in nanocrystalline NiCrAl matrix. Dense coating was deposited by cold spray at a gas temperature of 650 °C with the same phases and grain size as those of the starting powder. Vickers hardness test yielded a hardness of 1063 HV for the as-sprayed 20 vol.% cBN-NiCrAl coating. After annealed at 750 °C for 5 h, unbonded inter-particle boundaries were partially healed and evident grain growth of nanocrystalline NiCrAl was avoided. Wear resistance of the as-sprayed 20 vol.% cBN-NiCrAl nanocomposite coating was comparable to the HVOF-sprayed WC-12Co coating. Annealing of the nanocomposite coating resulted in the improvement of wear resistance by a factor of ~33% owing to the enhanced inter-particle bonding. Main material removal mechanisms during the abrasive wear are also discussed.

  12. Transformation of β-Ni(OH2to NiO nano-sheets via surface nanocrystalline zirconia coating: Shape and size retention

    Directory of Open Access Journals (Sweden)

    Cheng Ming-Yao

    2006-01-01

    Full Text Available AbstractShape and size of the synthesized NiO nano-sheets were retained during transformation of sheet-like β-Ni(OH2to NiO at elevated temperatures via nano-sized zirconia coating on the surface of β-Ni(OH2. The average grain size was 6.42 nm after 600 °C treatment and slightly increased to 10 nm after 1000 °C treatment, showing effective sintering retardation between NiO nano-sheets. The excellent thermal stability revealed potential application at elevated temperatures, especially for high temperature catalysts and solid-state electrochemical devices.

  13. Influence of Nitrided Layer on The Properties of Carbon Coatings Produced on X105CrMo17 Steel Under DC Glow-Discharge Conditions

    OpenAIRE

    Borowski, Tomasz; Ossowski, Maciej (OPI); Kowalczyk, Piotr; Maciej DUBEK; Agnieszka BROJANOWSKA; Krzysztof ROŻNIATOWSKI

    2016-01-01

    In most cases, machine components, which come in contact with each other, are made of steel. Common steel types include 100Cr6 and X105CrMo17 are widely used in rolling bearings, which are subjected to high static loads. However, more and more sophisticated structural applications require increasingly better performance from steel. The most popular methods for improving the properties of steel is carburisation or nitriding. Unfortunately, when very high surface properties of steel are require...

  14. Electrodeposited nanocrystalline bronze alloys as replacement for Ni

    NARCIS (Netherlands)

    Hovestad, A.; Tacken, R.A.; Mannetje, H.H.'t

    2008-01-01

    Nanocrystalline white-bronze, CuSn, electroplating was investigated as alternative to Ni plating as undercoat for noble metals in jewellery applications. A strongly acidic plating bath was developed with an organic additive to suppress hydrogen evolution and obtain bright coatings. Polarization curv

  15. Electrodeposited nanocrystalline bronze alloys as replacement for Ni

    NARCIS (Netherlands)

    Hovestad, A.; Tacken, R.A.; Mannetje, H.H.'t

    2008-01-01

    Nanocrystalline white-bronze, CuSn, electroplating was investigated as alternative to Ni plating as undercoat for noble metals in jewellery applications. A strongly acidic plating bath was developed with an organic additive to suppress hydrogen evolution and obtain bright coatings. Polarization

  16. Nanocrystalline Ni-Co Alloy Synthesis by High Speed Electrodeposition

    Directory of Open Access Journals (Sweden)

    Jamaliah Idris

    2013-01-01

    Full Text Available Electrodeposition of nanocrystals is economically and technologically viable production path for the synthesis of pure metals and alloys both in coatings and bulk form. The study presents nanocrystalline Ni-Co alloy synthesis by high speed electrodeposition. Nanocrystalline Ni-Co alloys coatings were prepared by direct current (DC and deposited directly on steel and aluminum substrates without any pretreatment, using high speed electrodeposition method. The influence of the electrolysis parameters, such as cathodic current density and temperature at constant pH, on electrodeposition and microstructure of Ni-Co alloys were examined. A homogeneous surface morphology was obtained at all current densities of the plated samples, and it was evident that the current density and temperature affect the coating thickness of Ni-Co alloy coatings.

  17. Electroless plating of thin gold films directly onto silicon nitride thin films and into micropores.

    Science.gov (United States)

    Whelan, Julie C; Karawdeniya, Buddini Iroshika; Bandara, Y M Nuwan D Y; Velleco, Brian D; Masterson, Caitlin M; Dwyer, Jason R

    2014-07-23

    A method to directly electrolessly plate silicon-rich silicon nitride with thin gold films was developed and characterized. Films with thicknesses plating free-standing ultrathin silicon nitride membranes, and we successfully plated the interior walls of micropore arrays in 200 nm thick silicon nitride membranes. The method is thus amenable to coating planar, curved, and line-of-sight-obscured silicon nitride surfaces.

  18. Crystalline boron nitride aerogels

    Science.gov (United States)

    Zettl, Alexander K.; Rousseas, Michael; Goldstein, Anna P.; Mickelson, William; Worsley, Marcus A.; Woo, Leta

    2017-04-04

    This disclosure provides methods and materials related to boron nitride aerogels. In one aspect, a material comprises an aerogel comprising boron nitride. The boron nitride has an ordered crystalline structure. The ordered crystalline structure may include atomic layers of hexagonal boron nitride lying on top of one another, with atoms contained in a first layer being superimposed on atoms contained in a second layer.

  19. Crystalline boron nitride aerogels

    Energy Technology Data Exchange (ETDEWEB)

    Zettl, Alexander K.; Rousseas, Michael; Goldstein, Anna P.; Mickelson, William; Worsley, Marcus A.; Woo, Leta

    2017-04-04

    This disclosure provides methods and materials related to boron nitride aerogels. In one aspect, a material comprises an aerogel comprising boron nitride. The boron nitride has an ordered crystalline structure. The ordered crystalline structure may include atomic layers of hexagonal boron nitride lying on top of one another, with atoms contained in a first layer being superimposed on atoms contained in a second layer.

  20. Nanocrystalline high-entropy alloy (CoCrFeNiAl 0.3 ) thin-film coating by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Weibing; Lan, Si; Gao, Libo; Zhang, Hongti; Xu, Shang; Song, Jian; Wang, Xunli; Lu, Yang

    2017-09-01

    High-entropy CoCrFeNiAl0.3 alloy thin films were prepared by magnetron sputtering technique. The thin film surface was very smooth and homogeneous. The synchrotron X-ray experiment confirmed that (111) type of texture existed in the thin film, and the structure was face-centered cubic nanocrystals with a minor content of ordered NiAl-type body-centered cubic structures. Interestingly, the elastic modulus of the thin film was nearly the same to the bulk single-crystal counterpart, however, the nanohardness is about four times of the bulk single-crystal counterpart. It was found that the high hardness was due to the formation of nanocrystal structure inside the thin films and the preferred growth orientation, which could be promising for applications in micro fabrication and advanced coating technologies.

  1. Synergistic strengthening effect of nanocrystalline copper reinforced with carbon nanotubes.

    Science.gov (United States)

    Wang, Hu; Zhang, Zhao-Hui; Hu, Zheng-Yang; Wang, Fu-Chi; Li, Sheng-Lin; Korznikov, Elena; Zhao, Xiu-Chen; Liu, Ying; Liu, Zhen-Feng; Kang, Zhe

    2016-05-17

    In this study, a novel multi-walled carbon nanotubes reinforced nanocrystalline copper matrix composite with super high strength and moderate plasticity was synthesized. We successfully overcome the agglomeration problem of the carbon nanotubes and the grain growth problem of the nanocrystalline copper matrix by combined use of the electroless deposition and spark plasma sintering methods. The yield strength of the composite reach up to 692 MPa, which is increased by 2 and 5 times comparing with those of the nanocrystalline and coarse copper, respectively. Simultaneously, the plasticity of the composite was also significantly increased in contrast with that of the nanocrystalline copper. The increase of the density of the carbon nanotubes after coating, the isolation effect caused by the copper coating, and the improvement of the compatibility between the reinforcements and matrix as well as the effective control of the grain growth of the copper matrix all contribute to improving the mechanical properties of the composite. In addition, a new strengthening mechanism, i.e., the series-connection effect of the nanocrystalline copper grains introduced by carbon nanotubes, is proposed to further explain the mechanical behavior of the nanocomposite.

  2. Bottom-up diamond nanorod growth in HFCVD from nanocrystalline diamond film as a template-free method

    Science.gov (United States)

    Motahari, Hamid; Malekfar, Rasoul

    2017-07-01

    Nanocrystalline diamond (NCD) films are being used in a large number of applications. Also, diamond nanorods (DNRs) exhibit distinctive features that are not present in diamond films, because of the tunable large surface-to-volume ratio and tubular configuration. In this work, we report on the synthesis of DNRs by means of the bottom-up and template-free method from NCD films by the hot filament chemical vapor deposition system. The substrate materials used for diamond deposition were stainless steel (AISI 316) and chromium nitride-coated stainless steel. On both substrates, NCD films and then DNRs have been synthesized. The micro-Raman confirms that the synthesized structure is NCD. In addition, the grazing incident x-ray diffraction pattern confirms the presence of cubic diamond and rhombohedral diamond as a film on the CrN and Cr2N interlayer. Also, the DNRs are encased in an amorphous carbon (a-C) shell. The DNRs are grown on the NCD grains by a bottom-up technology and template-free method. Their orientations are almost random in the diamond thin-film surface. In addition, the density of DNRs on the NCD film for the CrN interlayer is more than for the stainless-steel substrate. The NCD/DNR films are dense, adhesive, continuous, and almost uniform on the CrN-coated stainless-steel substrate.

  3. Boron nitride composites

    Energy Technology Data Exchange (ETDEWEB)

    Kuntz, Joshua D.; Ellsworth, German F.; Swenson, Fritz J.; Allen, Patrick G.

    2017-02-21

    According to one embodiment, a composite product includes: a matrix material including hexagonal boron nitride and one or more borate binders; and a plurality of cubic boron nitride particles dispersed in the matrix material. According to another embodiment, a composite product includes: a matrix material including hexagonal boron nitride and amorphous boron nitride; and a plurality of cubic boron nitride particles dispersed in the matrix material.

  4. 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. .

  5. Hemocompatibility of titanium nitride.

    Science.gov (United States)

    Dion, I; Baquey, C; Candelon, B; Monties, J R

    1992-10-01

    The left ventricular assist device is based on the principle of the Maillard-Wenkel rotative pump. The materials which make up the pump must present particular mechanical, tribological, thermal and chemical properties. Titanium nitride (TiN) because of its surface properties and graphite because of its bulk characteristics have been chosen. The present study evaluated the in vitro hemocompatibility of TiN coating deposited by the chemical vapor deposition process. Protein adsorption, platelet retention and hemolysis tests have been carried out. In spite of some disparities, the TiN behavior towards albumin and fibrinogen is interesting, compared with the one of a reference medical grade elastomer. The platelet retention test gives similar results as those achieved with the same elastomer. The hemolysis percentage is near to zero. TiN shows interesting characteristics, as far as mechanical and tribological problems are concerned, and presents very encouraging blood tolerability properties.

  6. Deformation in nanocrystalline metals

    Directory of Open Access Journals (Sweden)

    Helena Van Swygenhoven

    2006-05-01

    Full Text Available It is now possible to synthesize polycrystalline metals made up of grains that average less than 100 nm in size. Such nanocrystalline metals contain a significant volume fraction of interfacial regions separated by nearly perfect crystals. The small sizes involved limit the conventional operation of dislocation sources and thus a fundamental question arises: how do these materials deform plastically? We review the current views on deformation mechanisms in nanocrystalline, face-centered cubic metals based on insights gained by atomistic computer simulations. These insights are discussed with reference to recent striking experimental observations that can be compared with predictions made by the simulations.

  7. Nanocrystalline films for gas-reactive applications

    Science.gov (United States)

    Eastman, Jeffrey A.; Thompson, Loren J.

    2004-02-17

    A gas sensor for detection of oxidizing and reducing gases, including O.sub.2, CO.sub.2, CO, and H.sub.2, monitors the partial pressure of a gas to be detected by measuring the temperature rise of an oxide-thin-film-coated metallic line in response to an applied electrical current. For a fixed input power, the temperature rise of the metallic line is inversely proportional to the thermal conductivity of the oxide coating. The oxide coating contains multi-valent cation species that change their valence, and hence the oxygen stoichiometry of the coating, in response to changes in the partial pressure of the detected gas. Since the thermal conductivity of the coating is dependent on its oxygen stoichiometry, the temperature rise of the metallic line depends on the partial pressure of the detected gas. Nanocrystalline (<100 nm grain size) oxide coatings yield faster sensor response times than conventional larger-grained coatings due to faster oxygen diffusion along grain boundaries rather than through grain interiors.

  8. Correlation between microstructure and optical properties of nano-crystalline TiO{sub 2} thin films prepared by sol-gel dip coating

    Energy Technology Data Exchange (ETDEWEB)

    Mechiakh, R., E-mail: raouf_mechiakh@yahoo.fr [Departement de Medecine, Faculte de Medecine, Universite Hadj Lakhdar, Batna (Algeria); Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche des Sciences et Technologies de l' Energie, BP.95, Hammam-Lif 2050 (Tunisia); Laboratoire de Ceramiques, Universite Mentouri Constantine (Algeria); Sedrine, N. Ben; Chtourou, R. [Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche des Sciences et Technologies de l' Energie, BP.95, Hammam-Lif 2050 (Tunisia); Bensaha, R. [Laboratoire de Ceramiques, Universite Mentouri Constantine (Algeria)

    2010-11-15

    Titanium dioxide thin films have been prepared from tetrabutyl-orthotitanate solution and methanol as a solvent by sol-gel dip coating technique. TiO{sub 2} thin films prepared using a sol-gel process have been analyzed for different annealing temperatures. Structural properties in terms of crystal structure were investigated by Raman spectroscopy. The surface morphology and composition of the films were investigated by atomic force microscopy (AFM). The optical transmittance and reflectance spectra of TiO{sub 2} thin films deposited on silicon substrate were also determined. Spectroscopic ellipsometry study was used to determine the annealing temperature effect on the optical properties and the optical gap of the TiO{sub 2} thin films. The results show that the TiO{sub 2} thin films crystallize in anatase phase between 400 and 800 deg. C, and into the anatase-rutile phase at 1000 deg. C, and further into the rutile phase at 1200 deg. C. We have found that the films consist of titanium dioxide nano-crystals. The AFM surface morphology results indicate that the particle size increases from 5 to 41 nm by increasing the annealing temperature. The TiO{sub 2} thin films have high transparency in the visible range. For annealing temperatures between 1000 and 1400 deg. C, the transmittance of the films was reduced significantly in the wavelength range of 300-800 nm due to the change of crystallite phase and composition in the films. We have demonstrated as well the decrease of the optical band gap with the increase of the annealing temperature.

  9. Effect of plasma nitriding time on surface properties of hard chromium electroplated AISI 1010 steel

    Energy Technology Data Exchange (ETDEWEB)

    Kocabas, Mustafa [Yildiz Technical Univ., Istanbul (Turkey). Metallurgical and Materials Engineering Dept.; Danisman, Murat [Gedik Univ., Istanbul (Turkey). Electrical and Electronic Engineering Dept.; Cansever, Nurhan [Yildiz Technical Univ., Istanbul (Turkey); Uelker, Suekrue [Afyon Kocatepe Univ. (Turkey). Dept. of Mechanical Engineering

    2015-06-01

    Properties of steel can be enhanced by surface treatments such as coating. In some cases, further treatments such as nitriding can also be used in order to get even better results. In order to investigate the properties of nitride layer on hard Cr coated AISI 1010 steel, substrates were electroplated to form hard Cr coatings. Then hard Cr coatings were plasma nitrided at 700 C for 3 h, 5 h and 7 h and nitride phases on the coatings were investigated by X-ray diffraction analysis. The layer thickness and surface properties of nitride films were investigated by scanning electron microscopy. The hardness and adhesion properties of Cr-N phases were examined using nano indentation and Daimler-Benz Rockwell C adhesion tests. The highest measured hardness was 24.1 GPa and all the three samples exhibited poor adhesion.

  10. Electrodeposited nanocrystalline bronze alloys as replacement for Ni

    Energy Technology Data Exchange (ETDEWEB)

    Hovestad, A.; Tacken, R.A.; Mannetje, H.H. [TNO Science and Industry, Eindhoven (Netherlands)

    2008-07-01

    Nanocrystalline white-bronze, CuSn, electroplating was investigated as alternative to Ni plating as undercoat for noble metals in jewellery applications. A strongly acidic plating bath was developed with an organic additive to suppress hydrogen evolution and obtain bright coatings. Polarization curves indicate a strong inhibition by the organic additive at the tin equilibrium potential. Mass transfer controlled deposition yields nanocrystalline bronze coating with 0-65 wt% Sn. One or two low temperature equilibrium phases, high temperature equilibrium phases or a non-equilibrium phase were identified by XRD analyses. Bright white bronze, 50 wt% Cu/50 wt% Sn, bronze coatings show improved tarnishing resistance and similar corrosion and wear resistance as undercoat for gold on actual jewellery parts compared to nickel. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Nanocrystalline and Nanoporous Ceramics

    NARCIS (Netherlands)

    Verweij, Henk

    1996-01-01

    Nanocrystalline and nanoporous ceramics, renowned for their special transport properties, have typical applications in the fields of energy, the environment, and separation technology. One example is a solid oxide fuel cell, where an anode with improved characteristics was obtained by an optimized n

  12. Nanocrystalline Heterojunction Materials

    Science.gov (United States)

    Elder, Scott H.; Su, Yali; Gao, Yufei; Heald, Steve M.

    2004-02-03

    Mesoporous nanocrystalline titanium dioxide heterojunction materials and methods of making the same are disclosed. In one disclosed embodiment, materials comprising a core of titanium dioxide and a shell of a molybdenum oxide exhibit a decrease in their photoadsorption energy as the size of the titanium dioxide core decreases.

  13. RF-sputtered silicon and hafnium nitrides - Properties and adhesion to 440C stainless steel

    Science.gov (United States)

    Grill, A.; Aron, P. R.

    1983-01-01

    Silicon nitride and hafnium nitride coatings were deposited by reactive RF sputtering on oxidized and unoxidized 440C stainless steel substrates. Sputtering was done in mixtures of argon and nitrogen gases from pressed powder silicon nitride and from hafnium metal targets. Depositions were at two background pressures, 8 and 20 mtorr, and at two different fractions (f) of nitrogen in argon, 0.25 and 0.60, for hafnium nitride and at f = 0.25 for silicon nitride. The coatings and the interface between the coating and substrates were investigated by X-ray diffractometry, scanning electron microscopy, energy dispersive X-ray analysis and Auger electron spectroscopy. A Knoop microhardness of 1650 + or 100 kg/sq mm was measured for hafnium nitride and 3900 + or 500 kg/sq mm for silicon nitride. The friction coefficients between a 440C rider and the coatings were measured under lubricated conditions. Scratch test results demonstrate that the adhesion of hafnium nitride to both oxidized and unoxidized 440C is superior to that of silicon nitride. Oxidized 440C is found to have increased adhesion, to both nitrides, over that of unoxidized 440C.

  14. RF-sputtered silicon and hafnium nitrides - Properties and adhesion to 440C stainless steel

    Science.gov (United States)

    Grill, A.; Aron, P. R.

    1983-01-01

    Silicon nitride and hafnium nitride coatings were deposited by reactive RF sputtering on oxidized and unoxidized 440C stainless steel substrates. Sputtering was done in mixtures of argon and nitrogen gases from pressed powder silicon nitride and from hafnium metal targets. Depositions were at two background pressures, 8 and 20 mtorr, and at two different fractions (f) of nitrogen in argon, 0.25 and 0.60, for hafnium nitride and at f = 0.25 for silicon nitride. The coatings and the interface between the coating and substrates were investigated by X-ray diffractometry, scanning electron microscopy, energy dispersive X-ray analysis and Auger electron spectroscopy. A Knoop microhardness of 1650 + or 100 kg/sq mm was measured for hafnium nitride and 3900 + or 500 kg/sq mm for silicon nitride. The friction coefficients between a 440C rider and the coatings were measured under lubricated conditions. Scratch test results demonstrate that the adhesion of hafnium nitride to both oxidized and unoxidized 440C is superior to that of silicon nitride. Oxidized 440C is found to have increased adhesion, to both nitrides, over that of unoxidized 440C.

  15. Powder-based synthesis of nanocrystalline material components for structural application. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Ilyuschenko, A.F.; Ivashko, V.S.; Okovity, V.A. [Powder Metallurgy Research Inst., Minsk (Belarus)] [and others

    1998-12-01

    Hydroxiapate spray coatings and substrates for implant production as well as multilayered metal ceramic coatings from nanocrystalline materials are a subject of the investigation. The work aims at the improvement of quality of said objects. This study has investigated the processes of hydroxiapatite powder production. Sizes, shapes and relief of initial HA powder surface are analyzed using SEM and TEM. Modes of HA plasma spraying on a substrate from titanium and associated compositions of traditional and nanocrystalline structure are optimized. The quality of the sprayed samples are studied using X-ray phase analysis and metallographic analysis. The results of investigations of bioceramic coating spraying on titanium are theoretically generalized, taking into account obtained experimental data. The results of investigations of ion-beam technology are presented for spraying multilayered coatings consisting of alternating metal-ceramic layers of nanocrystalline structure.

  16. Composite coatings of titanium-aluminum nitride for steel against corrosion induced by solid NaCl deposit and water vapor at 600 °C

    Directory of Open Access Journals (Sweden)

    M.S. Li

    2004-03-01

    Full Text Available Composite coatings (Ti,AlN with different Al content were deposited on a wrought martensite steel 1Cr11Ni2W2MoV by reactive multi-arc ion plating. With the addition of Al to the coatings, the crystallographic structure of them changed from B1 NaCl to B4 ZnS, the relevant hardness and adhesive strength firstly increased then decreased and their oxidation-resistance was also dramatically improved. It was indicated that the introduction of Al was beneficial to (Ti,AlN coatings against corrosion induced by NaCl(s in wet oxygen at 600 °C as well as wet corrosion in NaCl solution at ambient temperature.

  17. Laboratory and Performance Studies of Anti-wear Coatings Deposited on Nitrided Surfaces of Tools used in an Industrial Hot Die Forging Process

    Science.gov (United States)

    Hawryluk, Marek; Widomski, Paweł; Smolik, Jerzy; Kaszuba, Marcin; Ziemba, Jacek; Gronostajski, Zbigniew

    2017-04-01

    The paper presents the results of laboratory studies performed on produced anti-wear coatings as well as the results of performance tests conducted on tools with these coatings in industrial conditions, in the process of hot die forging. Three different coatings were selected: AlCrTiSiN, Cr/CrN and AlCrTiN, deposited by means of the vacuum-arc method on test samples as well as forging tools used in the hot forging process of a lid. The first part of the paper discusses the results of the studies performed in laboratory conditions, which included: surface morphology by means of SEM, hardness and Young modulus measurements, determination of the chemical composition by means of the EDS method, adhesion tests by means of the scratch method and tribological tests by means of the ball-on-disk method. The obtained results were correlated and applied in the analysis of the performance tests on forging punches with these coatings at an early stage of their performance (up to 4000 produced forgings), which were tested on 19 tools, of which 3 representatives were selected for each coating. A thorough analysis was performed of the wear phenomena and mechanisms and the manner of wear of hybrid layers as well as their resistance to the particular destructive mechanisms. Based on the performed laboratory and performance studies as well as their analysis, it was possible to select the optimal hybrid layer, which enables an increase in the durability of forging tools used in industrial hot die forging processes. The preliminary results showed that the best results for the whole working surface of the tool were obtained for the Cr/CrN layer, which characterizes in high adhesion as well as a lower Young modulus and hardness. In the case of high pressures and the correlated friction, better results were obtained for the AlCrTiN coating, which, besides its good adhesion properties, also exhibited the highest frictional resistance.

  18. 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.

  19. Anticorrosion Nanocrystalline Beta Zeolite Thin Film for Advanced Applications

    Directory of Open Access Journals (Sweden)

    Maha Saud M. Al-subaie

    2015-01-01

    Full Text Available Steel alloys corrosion is ubiquitous and is conventionally protected by anticorrosion chromate coatings. However, the process suffers from the release of carcinogenic hexavalent chromium ions that needs to be replaced by an ecofriendly alternative. In this context, the need for the development of satisfactory ecofriendly chromium-free coating with superior corrosion performance is highly desirable. In the present study, we synthesized fully dispersible nanocrystalline Beta zeolite seeds and coated on steel alloys followed by steaming. The samples were characterized by XRD, FE-SEM, and DLS analyses. The anticorrosion behavior of the synthesized nanoparticle coatings on steel alloys was investigated by electrochemical measurements (DC polarization and electrochemical impedance spectroscopy (EIS in NaCl and acid and alkaline media under identical experimental conditions. The present study demonstrated that the nanozeolite coating can be a potential alternative for toxic and carcinogenic chromate coating.

  20. Bacterial adhesion to titanium-oxy-nitride (TiNOX) coatings with different resistivities : a novel approach for the development of biomaterials

    NARCIS (Netherlands)

    Koerner, RJ; Butterworth, LA; Mayer, [No Value; Dasbach, R; Busscher, HJ

    2002-01-01

    In this study the quantitative adhesion of a strain of Staphylococcus epidermidis, Streptococcus mutans and Pseudomonas aeruginosa to and the ease of removal from different TiNOX coatings was investigated by means of a parallel plate flow chamber and in situ image analysis. Quality of adhesion was d

  1. Bacterial adhesion to titanium-oxy-nitride (TiNOX) coatings with different resistivities : a novel approach for the development of biomaterials

    NARCIS (Netherlands)

    Koerner, RJ; Butterworth, LA; Mayer, [No Value; Dasbach, R; Busscher, HJ

    In this study the quantitative adhesion of a strain of Staphylococcus epidermidis, Streptococcus mutans and Pseudomonas aeruginosa to and the ease of removal from different TiNOX coatings was investigated by means of a parallel plate flow chamber and in situ image analysis. Quality of adhesion was

  2. Processing and optimization of functional ceramic coatings and inorganic nanomaterials

    Science.gov (United States)

    Nyutu, Edward Kennedy G.

    Processing of functional inorganic materials including zero (0-D) dimensional (e.g. nanoparticles), 1-D (nanorods, nanofibers), and 2-D (films/coating) structures is of fundamental and technological interest. This research will have two major sections. The first part of section one focuses on the deposition of silicon dioxide onto a pre-deposited molybdenum disilicide coating on molybdenum substrates for both high (>1000 °C) and moderate (500-600 °C) temperature oxidation protection. Chemical vapor deposition (CVD/MOCVD) techniques will be utilized to deposit the metal suicide and oxide coatings. The focus of this study will be to establish optimum deposition conditions and evaluate the metal oxide coating as oxidation - thermal barriers for Mo substrates under both isothermal (static) and cyclic oxidation conditions. The second part of this section will involve a systematic evaluation of a boron nitride (BN) interface coating prepared by chemical vapor deposition. Ceramic matrix composites (CMCs) are prospective candidates for high (>1000 °C) temperature applications and fiber- matrix interfaces are the dominant design parameters in ceramic matrix composites (CMCs). An important goal of the study is to determine a set of process parameters, which would define a boron nitride (BN) interface coating by a chemical vapor deposition (CVD) process with respect to coating. In the first part of the second section, we will investigate a new approach to synthesize ultrafine metal oxides that combines microwave heating and an in-situ ultrasonic mixing of two or more liquid precursors with a tubular flow reactor. Different metal oxides such as nickel ferrite and zinc aluminate spinels will be studied. The synthesis of metal oxides were investigated in order to study the effects of the nozzle and microwave (INM process) on the purity, composition, and particle size of the resulting powders. The second part of this research section involves a study of microwave frequency

  3. Fabrication and Characterization of Nanocrystalline VO2 Thin Films

    Institute of Scientific and Technical Information of China (English)

    WANG Hong-Chen; YI Xin-Jian; LAI Jian-Jun; LI Yi

    2005-01-01

    @@ Nanocrystalline VO2 films with phase transition temperature 34℃ have been fabricated on Si3N4-film-coated silicon and quartz substrates by argon-annealing films of metastable VO2(B). The original VO2(B) films are obtained by ion beam sputtering in an argon-oxygen atmosphere at 200 ℃. The nanocrystalline VO2 films exhibit strong changes in electrical and optical properties when a phase transition is completed. The phase transition temperature in the as-fabricated samples is about 34 ℃, which is smaller in comparison with 68 ℃ in the singlecrystalline VO2 material. A lower phase transition temperature is favorable for device applications such as smart window coating and low power consumption optical switching.

  4. Nanocrystalline Porous Hydrogen Storage Based on Vanadium and Titanium Nitrides

    Directory of Open Access Journals (Sweden)

    A. Goncharov

    2017-01-01

    Full Text Available This review summarizes results of our study of the application of ion-beam assisted deposition (IBAD technology for creation of nanoporous thin-film structures that can absorb more than 6 wt.% of hydrogen. Data of mathematical modeling are presented highlighting the structure formation and component creation of the films during their deposition at the time of simultaneous bombardment by mixed beam of nitrogen and helium ions with energy of 30 keV. Results of high-resolution transmission electron microscopy revealed that VNx films consist of 150–200 nm particles, boundaries of which contain nanopores of 10–15 nm diameters. Particles themselves consist of randomly oriented 10–20 nm nanograins. Grain boundaries also contain nanopores (3–8 nm. Examination of the absorption characteristics of VNx, TiNx, and (V,TiNx films showed that the amount of absorbed hydrogen depends very little on the chemical composition of films, but it is determined by the structure pore. The amount of absorbed hydrogen at 0.3 MPa and 20°C is 6-7 wt.%, whereas the bulk of hydrogen is accumulated in the grain boundaries and pores. Films begin to release hydrogen even at 50°C, and it is desorbed completely at the temperature range of 50–250°C. It was found that the electrical resistance of films during the hydrogen desorption increases 104 times.

  5. Structure characterization of nanocrystalline Ni–W alloys obtained by electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Indyka, P., E-mail: paulina.indyka@uj.edu.pl [Jagiellonian University, Faculty of Chemistry, 3 Ingardena St., 30-059 Krakow (Poland); Beltowska-Lehman, E.; Tarkowski, L.; Bigos, A. [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta St., 30-059 Krakow (Poland); García-Lecina, E. [Surface Finishing Department, CIDETEC-IK4 – Centre for Electrochemical Technologies, P° Miramón 196, 20009 Donostia-San Sebastián (Spain)

    2014-03-25

    Highlights: • Ni–W alloy coatings were electrodeposited from an aqueous electrolyte solutions. • The microstructure was studied with respect to electrodeposition process parameters. • We report optimal plating conditions for crack-free, nanocrystalline Ni–W coatings. • Crystalline Ni–W coatings exhibited the phase structure of an α-Ni(W) solid solution. • Coatings revealed tensile residual stresses and weakly pronounced 〈1 1 0〉 fiber texture. -- Abstract: Ni–W coatings of different tungsten content (2–50 wt%) were electrodeposited on a steel substrates from an aqueous complex sulfate–citrate galvanic baths, under controlled hydrodynamic conditions in a Rotating Disk Electrode (RDE) system. The optimum conditions for the electrodeposition of crack-free, homogeneous nanocrystalline Ni–W coatings were determined on the basis of the microstructure investigation results. The XRD structural characterizations of Ni–W alloy coatings obtained under different experimental conditions were complemented by SEM and TEM analysis. Results of the study revealed that the main factor influencing the microstructure formation of the Ni–W coatings is the chemical composition of an electrolyte solution. X-ray and electron diffraction patterns of all nanocrystalline Ni–W coatings revealed mainly the fcc phase structure of an α-Ni(W) solid solution with a lattice parameter increased along with tungsten content. The use of additives in the plating bath resulted in the formation of equiaxial/quasifibrous, nanocrystalline Ni–W grains of an average size of about 10 nm. The coatings were characterized by relatively high tensile residual stresses (500–1000 MPa), depending on the electrodeposition conditions. Ni–W coatings exhibited weakly pronounced fiber type 〈1 1 0〉 crystallographic texture, consistent with the symmetry of the plating process. Coatings of the highest tungsten content 50 wt% were found to be amorphous.

  6. The transformation of α-Fe into γ'-Fe4N in nanocrystalline Fe-N system: Influence of Gibbs-Thomson effect

    Science.gov (United States)

    Moszyński, Dariusz; Moszyńska, Izabela; Arabczyk, Walerian

    2013-12-01

    A nanocrystalline iron sample of non-uniform grain size distribution was nitrided at 500 °C under gas atmosphere with gradually increased nitriding potential. Mixtures of α-Fe and γ'-Fe4N phases were observed at a broad range of the nitriding potential. Unexpectedly, the mean size of the product's crystallites at small conversion degrees was much higher than the one observed initially for the substrate and gradually decreased with the advancement of the reaction. The observed behavior was explained by the reaction mechanism regarding the influence of the Gibbs-Thomson effect.

  7. Effect of nitride chemical passivation of the surface of GaAs photodiodes on their characteristics

    Science.gov (United States)

    Kontrosh, E. V.; Lebedeva, N. M.; Kalinovskiy, V. S.; Soldatenkov, F. Yu; Ulin, V. P.

    2016-11-01

    Characteristics of GaAs photodiodes have been studied before and after the chemical nitridation of their surface in hydrazine sulfide solutions, which leads to substitution of surface As atoms with N atoms to give a GaN monolayer. The resulting nitride coatings hinder the oxidation of GaAs in air and provide a decrease in the density of surface states involved in recombination processes. The device characteristics improved by nitridation are preserved during a long time.

  8. Comparison of Y3Al5O12:Ce0.05 phosphor coating methods for white-light-emitting diode on gallium nitride

    Science.gov (United States)

    Yum, Jun-Ho; Seo, Soo-Yeon; Lee, Seonghoon; Sung, Yung-Eun

    2001-12-01

    White light was obtained by mixing blue light from the emission of a GaN chip and a yellow light by the fluorescence of a Y3Al5O12:Ce0.05 yellow phosphor. A uniform coating of yellow phosphor on a GaN chip and an optimized thickness of a phosphor layer were necessary for achieving efficient white LED. Several methods for coating yellow phosphor particles such as the slurry method, the settling method, the electrophoretic deposition (EPD), and the modified EPD were examined for preparing the phosphor layer. The properties of the phosphor layer prepared by these methods were examined using SEM, XRD, and photoluminescence. The intensity of white light and the harmony between blue light and yellow light were dependent on the thickness of the phosphor layer. The properties of the phosphor layer made by the EPD such as packing density, thickness and uniformity could be more easily controlled than the slurry and settling methods. Further weak adhesion strength of phosphor particles by the EPD could be overcome via the use of a UV curable PVA+ADC layer on the phosphor layer in the EPD.

  9. Improving electrochemical properties of AISI 1045 steels by duplex surface treatment of plasma nitriding and aluminizing

    Energy Technology Data Exchange (ETDEWEB)

    Haftlang, Farahnaz, E-mail: f.haftlang@students.semnan.ac.ir [Department of Metallurgy and Materials Engineering, Faculty of Engineering, Semnan University, Semnan (Iran, Islamic Republic of); Habibolahzadeh, Ali [Department of Metallurgy and Materials Engineering, Faculty of Engineering, Semnan University, Semnan (Iran, Islamic Republic of); Sohi, Mahmoud Heydarzadeh [School of Metallurgy and Materials, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2015-02-28

    Highlights: • AlN coating was applied on AISI 1045 steel via plasma nitriding and aluminizing. • Plasma nitriding and post-aluminizing result in AlN single phase layer on the steel. • PN–Al coated steel had better corrosion resistance than Al–PN one. • Formation of oxide layer provided protection of PN–Al coated steel against corrosion. • Pitting and surface defects was the dominant corrosion mechanism in Al–PN coated steel. - Abstract: Improvement in electrochemical behavior of AISI 1045 steel after applying aluminum nitride coating was investigated in 3.5% NaCl solution, using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) analyses. Aluminum nitride coating was applied on the steel surface by duplex treatment of pack aluminizing and plasma nitriding. Some specimens were plasma nitrided followed by aluminizing (PN–Al), while the others were pack aluminized followed by plasma nitriding (Al–PN). Topological and structural studies of the modified surfaces were conducted using scanning electron microscope (SEM) equipped by energy dispersive X-ray spectroscope (EDS), and X-ray diffractometer (XRD). The electrochemical measurements showed that the highest corrosion and polarization (R{sub p}) resistances were obtained in PN–Al specimens, having single phase superficial layer of AlN. Pitting mechanism was dominant reason of lower corrosion resistance in the Al–PN specimens.

  10. The hardness, adhesion, and wear resistance of coatings developed for cobalt-base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Cockeram, B.V.; Wilson, W.L.

    2000-05-01

    One potential approach for reducing the level of nuclear plant radiation exposure that results from activated cobalt wear debris is the use of a wear resistant coating. However, large differences in stiffness between a coating/substrate can result in high interfacial stresses that produce coating de-adhesion when a coated substrate is subjected to high stress wear contact. Scratch adhesion and indentation tests have been used to identify four promising coating processes [1,2]: (1) the use of a thin Cr-nitride coating with a hard and less-stiff interlayer, (2) the use of a thick, multilayered Cr-nitride coating with graded layers, (3) use of the duplex approach, or nitriding to harden the material subsurface followed by application of a multilayered Cr-nitride coating, and (4) application of nitriding alone. The processing, characterization, and adhesion of these coating systems are discussed. The wear resistance and performance has been evaluated using laboratory pin-on-disc, 4-ball, and high stress rolling contact tests. Based on the results of these tests, the best coating candidate from the high-stress rolling contact wear test was the thin duplex coating, which consists of ion nitriding followed deposition of a thin Cr-nitride coating, while the thin Cr-nitride coating exhibited the best results in the 4-ball wear test.

  11. Dislocation Dynamics in Nanocrystalline Nickel

    OpenAIRE

    Shan, Z. W.; Wiezorek, J. M. K.; Stach, E. A.; Follstaedt, D. M.; Knapp, J. A.; Mao, S. X.

    2007-01-01

    It is believed that the dynamics of dislocation processes during the deformation of nanocrystalline materials can only be visualized by computational simulations. Here we demonstrate that observations of dislocation processes during the deformation of nanocrystalline Ni with grain sizes as small as 10 nm can be achieved by using a combination of in situ tensile straining and high-resolution transmission electron microscopy. Trapped unit lattice dislocations are observed in strained grains...

  12. Study on the Structure and Corrosion-resistant Performance of Phosphate/Silicon Nitride Double Composite Coating on Magnesium Alloy%镁合金磷酸盐/氮化硅双层复合膜结构及耐蚀性能研究

    Institute of Scientific and Technical Information of China (English)

    宋辉; 赵明; 何广平; 冯伟

    2014-01-01

    Objective To solve the problems of traditional chemical conversion coatings on magnesium alloy such as large micro-cracks and poor corrosion resistance, a novel phosphate/ silicon nitride compound coating was prepared in this article. Methods First traditional magnesium phosphate conversion treatment was conducted, and then plasma enhanced chemical vapor deposition technology was used to deposit silicon nitride film layer. The morphology, element distribution, surface potential and polarization curve of the composite coating were analyzed, and compared with those of the phosphate conversion coating. Results Silicon nitride film layer could be selectively priorly deposited on the cracking positions of the phosphate conversion coating, and filled the cracks on the conversion coating layer, forming dense composite coating structure. The surface potential and corrosion potential of magne-sium alloy with composite coating structure were significantly higher than those of magnesium alloy treated with traditional phosphate conversion process. Conclusion After preparation of phosphate/ silicon nitride double composite coating on the surface of magnesi-um alloy, the corrosion resistance was significantly higher than that of the magnesium alloy treated with traditional phosphate con-version.%目的:针对传统镁合金化学转化膜裂纹尺寸大、耐腐蚀性差等问题,制备一种镁合金磷酸盐/氮化硅双层结构的抗腐蚀复合膜。方法先对镁合金进行传统磷酸盐转化处理,再运用等离子体增强化学气相沉积技术沉积氮化硅膜层,分析复合膜的形貌、元素分布、表面电位及极化曲线,并与磷酸盐转化膜进行对比。结果氮化硅膜层能在磷酸盐转化膜裂纹处选择性优先沉积,从而在相当程度上填补转化膜层的裂纹,形成致密的复合膜结构。具有复合膜结构的镁合金表面电位和腐蚀电位明显高于传统磷酸盐转化处理的镁合金。结论

  13. Method and apparatus for use of III-nitride wide bandgap semiconductors in optical communications

    Energy Technology Data Exchange (ETDEWEB)

    Hui, Rongqing (Lenexa, KS); Jiang,Hong-Xing (Manhattan, KS); Lin, Jing-Yu (Manhattan, KS)

    2008-03-18

    The present disclosure relates to the use of III-nitride wide bandgap semiconductor materials for optical communications. In one embodiment, an optical device includes an optical waveguide device fabricated using a III-nitride semiconductor material. The III-nitride semiconductor material provides for an electrically controllable refractive index. The optical waveguide device provides for high speed optical communications in an infrared wavelength region. In one embodiment, an optical amplifier is provided using optical coatings at the facet ends of a waveguide formed of erbium-doped III-nitride semiconductor materials.

  14. Nanocrystalline diamond films for biomedical applications

    DEFF Research Database (Denmark)

    Pennisi, Cristian Pablo; Alcaide, Maria

    2014-01-01

    Nanocrystalline diamond films, which comprise the so called nanocrystalline diamond (NCD) and ultrananocrystalline diamond (UNCD), represent a class of biomaterials possessing outstanding mechanical, tribological, and electrical properties, which include high surface smoothness, high corrosion re...

  15. Bond Angles in the Crystalline Silicon/Silicon Nitride Interface

    Science.gov (United States)

    Leonard, Robert H.; Bachlechner, Martina E.

    2006-03-01

    Silicon nitride deposited on a silicon substrate has major applications in both dielectric layers in microelectronics and as antireflection and passivation coatings in photovoltaic applications. Molecular dynamic simulations are performed to investigate the influence of temperature and rate of externally applied strain on the structural and mechanical properties of the silicon/silicon nitride interface. Bond-angles between various atom types in the system are used to find and understand more about the mechanisms leading to the failure of the crystal. Ideally in crystalline silicon nitride, bond angles of 109.5 occur when a silicon atom is at the vertex and 120 angles occur when a nitrogen atom is at the vertex. The comparison of the calculated angles to the ideal values give information on the mechanisms of failure in silicon/silicon nitride system.

  16. Ferroelectric polarization in nanocrystalline hydroxyapatite thin films on silicon.

    Science.gov (United States)

    Lang, S B; Tofail, S A M; Kholkin, A L; Wojtaś, M; Gregor, M; Gandhi, A A; Wang, Y; Bauer, S; Krause, M; Plecenik, A

    2013-01-01

    Hydroxyapatite nanocrystals in natural form are a major component of bone--a known piezoelectric material. Synthetic hydroxyapatite is widely used in bone grafts and prosthetic pyroelectric coatings as it binds strongly with natural bone. Nanocrystalline synthetic hydroxyapatite films have recently been found to exhibit strong piezoelectricity and pyroelectricity. While a spontaneous polarization in hydroxyapatite has been predicted since 2005, the reversibility of this polarization (i.e. ferroelectricity) requires experimental evidence. Here we use piezoresponse force microscopy to demonstrate that nanocrystalline hydroxyapatite indeed exhibits ferroelectricity: a reversal of polarization under an electrical field. This finding will strengthen investigations on the role of electrical polarization in biomineralization and bone-density related diseases. As hydroxyapatite is one of the most common biocompatible materials, our findings will also stimulate systematic exploration of lead and rare-metal free ferroelectric devices for potential applications in areas as diverse as in vivo and ex vivo energy harvesting, biosensing and electronics.

  17. Ferroelectric Polarization in Nanocrystalline Hydroxyapatite Thin Films on Silicon

    Science.gov (United States)

    Lang, S. B.; Tofail, S. A. M.; Kholkin, A. L.; Wojtaś, M.; Gregor, M.; Gandhi, A. A.; Wang, Y.; Bauer, S.; Krause, M.; Plecenik, A.

    2013-07-01

    Hydroxyapatite nanocrystals in natural form are a major component of bone- a known piezoelectric material. Synthetic hydroxyapatite is widely used in bone grafts and prosthetic pyroelectric coatings as it binds strongly with natural bone. Nanocrystalline synthetic hydroxyapatite films have recently been found to exhibit strong piezoelectricity and pyroelectricity. While a spontaneous polarization in hydroxyapatite has been predicted since 2005, the reversibility of this polarization (i.e. ferroelectricity) requires experimental evidence. Here we use piezoresponse force microscopy to demonstrate that nanocrystalline hydroxyapatite indeed exhibits ferroelectricity: a reversal of polarization under an electrical field. This finding will strengthen investigations on the role of electrical polarization in biomineralization and bone-density related diseases. As hydroxyapatite is one of the most common biocompatible materials, our findings will also stimulate systematic exploration of lead and rare-metal free ferroelectric devices for potential applications in areas as diverse as in vivo and ex vivo energy harvesting, biosensing and electronics.

  18. Protection of aluminium by duplex coatings

    Energy Technology Data Exchange (ETDEWEB)

    Musil, J. [Ceska Akademie Ved, Prague (Czech Republic). Fyzikalni Ustav; Vlcek, J. [West Bohemia Univ., Plzen (Czech Republic). Dept. of Phys.; Jezek, V. [West Bohemia Univ., Plzen (Czech Republic). Dept. of Phys.; Benda, M. [West Bohemia Univ., Plzen (Czech Republic). Dept. of Phys.

    1995-11-01

    The paper reports on a new way of producing duplex coatings consisting of two steps. First, the substrate is coated by a physically vapour-deposited coating. Then, this precoated substrate is plasma nitrided or vacuum heat treated. This method was tested in the protection of substrates made of aluminium with a sputtered Ti coating about 5 {mu}m thick. The as-deposited and then plasma-nitrided or vacuum-heat-treated (Ti coating)/(Al substrate) couple was characterized by elemental depth profiles measured by glow discharge optical spectroscopy. It was shown that both the plasma nitriding and vacuum heat treatment process can stimulate a strong interdiffusion between Ti and the substrate elements. It results not only in the formation of a very broad interfacial region with a dramatic redistribution of the substrate elements in the Ti film but also in a formation of intermetallic Ti-Al compounds. This new duplex coating technique is described in detail. (orig.)

  19. Systematic Study of Nanocrystalline Plasma Electrolytic Nitrocarburising of 316L Austenitic Stainless Steel for Corrosion Protection

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A number of studies have been reported on the use of nanocrystalline plasma electrolytic nitrocarburising technology for surface hardening of stainless steels for higher corrosion resistance resulted from this technique. However, very few studies have focused on the optimization of the nanocrystalline plasma electrolytic nitrocarburising process parameters. In this study, a design of experiment (DOE) technique, the Taguchi method, has been used to optimize the nanocrystalline plasma electrolytic nitrocarburising not only for surface hardening but also for the corrosion protection of 316L austenitic stainless steel by controlling the coating process's factors. The experimental design consisted of four factors (Urea concentration, electrical conductivity of electrolyte, voltage and duration of process), each containing three levels. Potentiodynamic polarization measurements were carried out to determine the corrosion resistance of the coated samples. The results were analyzed with related software. An analysis of the mean of signal-to-noise (S/N) ratio indicated that the corrosion resistance of nanocrystalline plasma electrolytic nitrocarburised 316L stainless steel was influenced significantly by the levels in the Taguchi orthogonal array. The optimized coating parameters for corrosion resistance are 1150 g/L for urea concentration, 360 mS/cm for electrical conductivity of electrolyte, 260 V for applied voltage, 6 min for treatment time. The percentage of contribution for each factor was determined by the analysis of variance (ANOVA). The results showed that the applied voltage is the most significant factor affecting the corrosion resistance of the coatings.

  20. Wear behaviour of wear-resistant adaptive nano-multilayered Ti-Al-Mo-N coatings

    Science.gov (United States)

    Sergevnin, V. S.; Blinkov, I. V.; Volkhonskii, A. O.; Belov, D. S.; Kuznetsov, D. V.; Gorshenkov, M. V.; Skryleva, E. A.

    2016-12-01

    Coating samples in the Ti-Al-Mo-N system were obtained by arc-PVD method at variable bias voltage Ub applied to the substrate, and the partial pressure of nitrogen P(N2) used as a reaction gas. The deposited coatings were characterized by a nanocrystalline structure with an average grain size of 30-40 nm and multilayered architecture with alternating layers of (Ti,Al)N nitride and Mo-containing phases with a thickness comparable to the grain size. Coatings of (Ti,Al)N-Mo-Mo2N and (Ti,Al)N-Mo2N compositions were obtained by changing deposition parameters. The obtained coatings had hardness of 40 GPa and the relative plastic deformation under microindentation up to 60%. (Ti,Al)N-Mo2N coatings demonstrated better physicomechanical characteristics, showing high resistance to crack formation and destruction through the plastic deformation mechanism without brittle fracturing, unlike (Ti,Al)N-Mo-Mo2N. The friction coefficient of the study coatings (against Al2O3 balls under dry condition using a pin-on-disc method) reached the values of 0.35 and 0.5 at 20 °C and 500 °C respectively, without noticeable wear within this temperature range. These tribological properties were achieved by forming MoO3 acting as a solid lubricant. At higher temperatures the deterioration in the tribological properties is due to the high rate of MoO3 sublimation from friction surfaces.

  1. Silver film on nanocrystalline TiO{sub 2} support: Photocatalytic and antimicrobial ability

    Energy Technology Data Exchange (ETDEWEB)

    Vukoje, Ivana D., E-mail: ivanav@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11000 Belgrade (Serbia); Tomašević-Ilić, Tijana D., E-mail: tommashev@gmail.com [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11000 Belgrade (Serbia); Zarubica, Aleksandra R., E-mail: zarubica2000@yahoo.com [Department of Chemistry, Faculty of Science and Mathematics, University of Niš, Višegradska 33, 18000 Niš (Serbia); Dimitrijević, Suzana, E-mail: suzana@tmf.bg.ac.rs [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade (Serbia); Budimir, Milica D., E-mail: mickbudimir@gmail.com [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11000 Belgrade (Serbia); Vranješ, Mila R., E-mail: mila@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11000 Belgrade (Serbia); Šaponjić, Zoran V., E-mail: saponjic@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11000 Belgrade (Serbia); Nedeljković, Jovan M., E-mail: jovned@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11000 Belgrade (Serbia)

    2014-12-15

    Highlights: • Simple photocatalytic rout for deposition of Ag on nanocrystalline TiO{sub 2} films. • High antibactericidal efficiency of deposited Ag on TiO{sub 2} support. • Improved photocatalytic performance of TiO{sub 2} films in the presence of deposited Ag. - Abstract: Nanocrystalline TiO{sub 2} films were prepared on glass slides by the dip coating technique using colloidal solutions consisting of 4.5 nm particles as a precursor. Photoirradiation of nanocrystalline TiO{sub 2} film modified with alanine that covalently binds to the surface of TiO{sub 2} and at the same time chelate silver ions induced formation of metallic silver film. Optical and morphological properties of thin silver films on nanocrystalline TiO{sub 2} support were studied by absorption spectroscopy and atomic force microscopy. Improvement of photocatalytic performance of nanocrystalline TiO{sub 2} films after deposition of silver was observed in degradation reaction of crystal violet. Antimicrobial ability of deposited silver films on nanocrystalline TiO{sub 2} support was tested in dark as a function of time against Escherichia coli, Staphylococcus aureus, and Candida albicans. The silver films ensured maximum cells reduction of both bacteria, while the fungi reduction reached satisfactory 98.45% after 24 h of contact.

  2. Preparation and characterization of boron nitride/carbon fiber composite with high specific surface area

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yan; Fan, Mingwen [Wuhan Univ. (China). Key Laboratory for Oral Biomedical Engineering; Yuan, Songdong; Xiong, Kun; Hu, Kunpeng; Luo, Yi [Hubei Univ. of Technology, Wuhan (China). School of Chemistry and Chemical Engineering; Li, Dong [Hubei Univ. of Technology, Wuhan (China). School of Chemistry and Chemical Engineering; Oxford Univ. (United Kingdom). Chemistry Research Lab.

    2014-06-15

    Boron nitride can be used as a good catalyst carrier because of its high thermal conductivity and chemical stability. However, a high specific surface area of boron nitride is still desirable. In this work, a carbon fiber composite coated with boron nitride villous nano-film was prepared, and was also characterized by means of scanning electron microscopy, high resolution transmission electron microscopy, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller analysis. The results indicated that the carbon fibers were covered by uniform villous boron nitride films whose thickness was about 150 - 200 nm. The specific surface area of the boron nitride/carbon fiber composite material was 96 m{sup 2} g{sup -1}, which was markedly improved compared with conventional boron nitride materials. (orig.)

  3. Nanostructured multielement (TiHfZrNbVTa)N coatings before and after implantation of N+ ions (10{sup 18} cm{sup −2}): Their structure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Pogrebnjak, A.D., E-mail: alexp@i.ua [Sumy State University, Department of Nanoelectronics, 40007, R.-Korsakova 2, Sumy (Ukraine); Bondar, O.V., E-mail: oleksandr.v.bondar@gmail.com [Sumy State University, Department of Nanoelectronics, 40007, R.-Korsakova 2, Sumy (Ukraine); Borba, S.O. [Sumy State University, Department of Nanoelectronics, 40007, R.-Korsakova 2, Sumy (Ukraine); Abadias, G. [Institut Pprime, CNRS, Université de Poitiers, ISAE-ENSMA, F86962 Futuroscope Chasseneuil (France); Konarski, P. [Tele and Radio Research Institute, Ratuszowa 11, 03-450 Warsaw (Poland); Plotnikov, S.V. [D. Serikbaev East-Kazakhstan State Technical University, 070004, Ust-Kamenogorsk, 69 Protozanov St. (Kazakhstan); Beresnev, V.M. [V.N. Karazin Kharkiv National University, 61022, Svobody Sq. 4, Kharkiv (Ukraine); Kassenova, L.G. [Kazakh University of Economics, Finance and International Trade, St. Zhubanov 7, 010005 Astana (Kazakhstan); Drodziel, P. [Lublin University of Technology, Nadbystrzycka 36, 20-618 Lublin (Poland)

    2016-10-15

    Highlights: • (TiZrHfVNbTa)N coatings were deposited by vacuum–arc evaporation of a cathode. • Nanostructured coatings were investigated experimentally and by MD simulations. • Good correlation between experimental data and simulation results is observed. • Ion implantation formed amorphous, nanocrystalline and nanostructured layers. • Hardness changed from 12 GPa in the implanted layer to 38 GPa with the depth. - Abstract: Multielement high entropy alloy (HEA) nitride (TiHfZrNbVTa)N coatings were deposited by vacuum arc and their structural and mechanical stability after implantation of high doses of N{sup +} ions, 10{sup 18} cm{sup −2}, were investigated. The crystal structure and phase composition were characterized by X-ray diffraction (XRD) and Transmission Electron Microscopy, while depth-resolved nanoindentation tests were used to determine the evolution of hardness and elastic modulus along the implantation depth. XRD patterns show that coatings exhibit a main phase with fcc structure, which preferred orientation varies from (1 1 1) to (2 0 0), depending on the deposition conditions. First-principles calculations reveal that the presence of Nb atoms could favor the formation of solid solution with fcc structure in multielement HEA nitride. TEM results showed that amorphous and nanostructured phases were formed in the implanted coating sub-surface layer (∼100 nm depth). Concentration of nitrogen reached 90 at% in the near-surface layer after implantation, and decreased at higher depth. Nanohardness of the as-deposited coatings varied from 27 to 38 GPa depending on the deposition conditions. Ion implantation led to a significant decrease of the nanohardness to 12 GPa in the implanted region, while it reaches 24 GPa at larger depths. However, the H/E ratio is ⩾0.1 in the sub-surface layer due to N{sup +} implantation, which is expected to have beneficial effect on the wear properties.

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

    Energy Technology Data Exchange (ETDEWEB)

    Dante, Roberto C., E-mail: rcdante@yahoo.com [Laboratorio de Tecnologias del Medio Ambiente, Departamento de Ingenieria Agricola y Forestal, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain); Martin-Ramos, Pablo, E-mail: pablomartinramos@gmail.com [Laboratorio de Tecnologias del Medio Ambiente, Departamento de Ingenieria Agricola y Forestal, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain); Correa-Guimaraes, Adriana, E-mail: acg@iaf.uva.es [Laboratorio de Tecnologias del Medio Ambiente, Departamento de Ingenieria Agricola y Forestal, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain); Martin-Gil, Jesus, E-mail: jesusmartingil@gmail.com [Laboratorio de Tecnologias del Medio Ambiente, Departamento de Ingenieria Agricola y Forestal, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain)

    2011-11-01

    Highlights: {yields} Graphitic carbon nitrides by CVD of melamine and uric acid on alumina. {yields} The building blocks of carbon nitrides are heptazine nuclei. {yields} 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.

  5. Stress in and texture of PVD deposited metal nitride films

    NARCIS (Netherlands)

    Machunze, R.

    2010-01-01

    Thin metal nitride films deposited by Physical Vapor Deposition (PVD) are used amongst many other applications as wear protective coatings in tool industry or as diffusion barriers in integrated circuit technology. Typically these films exhibit a residual in-plane stress when deposited onto rigid su

  6. Characterisation of interfaces in nanocrystalline palladium

    Indian Academy of Sciences (India)

    R Divakar; V S Raghunathan

    2003-02-01

    Structures of grain boundaries and triple line junctions in nanocrystalline materials are of interest owing to large fractions of atoms in nanocrystalline materials being at these interfacial positions. Grain boundary and triple line junction structures in nanocrystalline palladium have been studied using high-resolution transmission electron microscopy (HRTEM). The main microstructural features observed include the varying atomic structures of grain boundaries and the presence of disordered regions at triple line junctions. Also, there is variation in lattice parameters in different nanocrystalline grains. Geometric phase analysis is used to quantify atomic displacements within nanocrystalline grains. Displacement fields thus detected indicate links to the interface structures.

  7. Gallium nitride optoelectronic devices

    Science.gov (United States)

    Chu, T. L.; Chu, S. S.

    1972-01-01

    The growth of bulk gallium nitride crystals was achieved by the ammonolysis of gallium monochloride. Gallium nitride single crystals up to 2.5 x 0.5 cm in size were produced. The crystals are suitable as substrates for the epitaxial growth of gallium nitride. The epitaxial growth of gallium nitride on sapphire substrates with main faces of (0001) and (1T02) orientations was achieved by the ammonolysis of gallium monochloride in a gas flow system. The grown layers had electron concentrations in the range of 1 to 3 x 10 to the 19th power/cu cm and Hall mobilities in the range of 50 to 100 sq cm/v/sec at room temperature.

  8. Synthesis of Superhydrophobic Nanocomposite Coatings Using Electrodeposition

    Science.gov (United States)

    Iacovetta, Daniel John

    The focus of the current research is to produce a metal matrix composite material that possesses a superhydrophobic surface using electrodeposition. The objective is to create a multifunctional coating that is able to provide high strength as well as high water repellency using nanocrystalline nickel and polytetrafluoroethylene (PTFE) particles. The co-deposition process was first studied. It was determined that the amount of PTFE co-deposited is highly dependent on the concentration of PTFE particles in the electroplating bath. The wetting angle of the surface greatly increased when the PTFE content increases. Next the electroplating procedure of pure nickel is altered to produce a nanocrystalline material, resulting in a large increase in the hardness of the nickel coatings. The two techniques are combined to produce a nanocrystalline Nickel-PTFE composite. Under optimum conditions, the composite coating displayed a highly water repellent surface and improved mechanical properties.

  9. Nanocrystalline magnetic alloys and ceramics

    Indian Academy of Sciences (India)

    M Pal; D Chakravorty

    2003-02-01

    Magnetic properties of materials in their nanocrystalline state have assumed significance in recent years because of their potential applications. A number of techniques have been used to prepare nanocrystalline magnetic phases. Melt spinning, high energy ball milling, sputtering, glassceramization and molecular beam epitaxy are some of the physical methods used so far. Among the chemical methods, sol-gel and co-precipitation routes have been found to be convenient. Ultrafine particles of both ferro- and ferrimagnetic systems show superparamagnetic behaviour at room temperature. Coercivity $(H_c)$ and maximum energy product $(BH)_{\\text{max}}$ of the magnetic particles can be changed by controlling their sizes. The present paper reviews all these aspects in the case of nanocrystalline magnetic systems — both metallic and ceramics.

  10. Boron Nitride Nanotubes

    Science.gov (United States)

    Smith, Michael W. (Inventor); Jordan, Kevin (Inventor); Park, Cheol (Inventor)

    2012-01-01

    Boron nitride nanotubes are prepared by a process which includes: (a) creating a source of boron vapor; (b) mixing the boron vapor with nitrogen gas so that a mixture of boron vapor and nitrogen gas is present at a nucleation site, which is a surface, the nitrogen gas being provided at a pressure elevated above atmospheric, e.g., from greater than about 2 atmospheres up to about 250 atmospheres; and (c) harvesting boron nitride nanotubes, which are formed at the nucleation site.

  11. Boron nitride composites

    Science.gov (United States)

    Kuntz, Joshua D.; Ellsworth, German F.; Swenson, Fritz J.; Allen, Patrick G.

    2016-02-16

    According to one embodiment, a composite product includes hexagonal boron nitride (hBN), and a plurality of cubic boron nitride (cBN) particles, wherein the plurality of cBN particles are dispersed in a matrix of the hBN. According to another embodiment, a composite product includes a plurality of cBN particles, and one or more borate-containing binders.

  12. Boron nitride composites

    Energy Technology Data Exchange (ETDEWEB)

    Kuntz, Joshua D.; Ellsworth, German F.; Swenson, Fritz J.; Allen, Patrick G.

    2016-02-16

    According to one embodiment, a composite product includes hexagonal boron nitride (hBN), and a plurality of cubic boron nitride (cBN) particles, wherein the plurality of cBN particles are dispersed in a matrix of the hBN. According to another embodiment, a composite product includes a plurality of cBN particles, and one or more borate-containing binders.

  13. Effect of SPD surface layer on plasma nitriding of Ti–6Al–4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Farokhzadeh, K.; Qian, J.; Edrisy, A., E-mail: edrisy@uwindsor.ca

    2014-01-01

    A severe plastic deformation (SPD) surface layer was introduced by shot peening to enhance the nitriding kinetics in low-temperature (600 °C) plasma nitriding of Ti–6Al–4V alloy. The effect of this pretreatment on the nitrided microstructures and phase compositions was investigated by analytical microscopy techniques e.g. scanning and transmission electron microscopy (SEM, TEM) and X-ray diffraction (XRD) analysis. Microstructural investigations revealed the formation of a compound layer consisting of a 0.6 µm thick nanocrystalline TiN layer followed by a 0.5 µm thick layer of Ti{sub 2}N with a larger grain size (0.1–0.5 µm). The development of TiN nanograins was attributed to accelerated nitriding kinetics due to the increased preferential nucleation sites in the SPD layer. Furthermore, the thickness of nitrogen diffusion zone (DZ) increased by 50% in the pretreated plasma nitrided alloy when compared with that of the untreated one. This is likely promoted by an increase in density of subsurface microstructural defects, such as twins and grain boundaries. The sliding behaviour and interfacial adhesion of the nitrided surfaces were evaluated by micro-scratch tests within a load range of 1–20 N. Compared with untreated-plasma-nitrided alloy, the pretreated nitrided surfaces exhibited a higher load bearing capacity and better interfacial bonding. They exhibited no chipping or spallation, even after multiple sliding passes at the highest applied load of 20 N in contrary to the untreated plasma nitrided surfaces.

  14. Influence of the Discharge Voltage during Pulse-Plasma Process on the Durability of Edges coated with Superhard Coatings

    Institute of Scientific and Technical Information of China (English)

    Maciej Kupczyk

    2004-01-01

    In the paper the experimental results concerning the functional quality of thin, superhard coatings produced on cutting edges is described. Boron nitride coatings were deposited on insert cutting edges made cemented carbides by the pulse-plasma method. The comparative investigations of mentioned coatings have been concerned of tool life of edges during steel machining. In these investigations for the purpose of additional increase of coated edge durability an interfacial layers were applied. Presented investigations particularly pointed out to essential influence of the values of discharge voltage on the coating structure and durability of edges coated with boron nitride.

  15. Nitrogen Availability Of Nitriding Atmosphere In Controlled Gas Nitriding Processes

    Directory of Open Access Journals (Sweden)

    Michalski J.

    2015-06-01

    Full Text Available Parameters which characterize the nitriding atmosphere in the gas nitriding process of steel are: the nitriding potential KN, ammonia dissociation rate α and nitrogen availabilitymN2. The article discusses the possibilities of utilization of the nitriding atmosphere’s nitrogen availability in the design of gas nitriding processes of alloyed steels in atmospheres derived from raw ammonia, raw ammonia diluted with pre-dissociated ammonia, with nitrogen, as well as with both nitrogen and pre-dissociated ammonia. The nitriding processes were accomplished in four series. The parameters selected in the particular processes were: process temperature (T, time (t, value of nitriding potential (KN, corresponding to known dissociation rate of the ammonia which dissociates during the nitriding process (α. Variable parameters were: nitrogen availability (mN2, composition of the ingoing atmosphere and flow rate of the ingoing atmosphere (FIn.

  16. Protective metal matrix coating with nanocomponents

    Science.gov (United States)

    Galevsky, G. V.; Rudneva, V. V.; Cherepanov, A. N.; Galevsky, S. G.; Efimova, K. A.

    2016-09-01

    Experience of nanocrystalline chromium, titanium, silicon carbides and borides components application as nickel, zinc, chromium based electrodeposited composite coating is generalized. Electrodepositing conditions are determined. Structure and physicochemical properties of coatings, namely micro-hardness, adhesion to steel base, inherent stresses, heat resistance, corrosion currents, en-during quality, and their change during isothermal annealing are studied. As is shown, nanocomponents act as metal matrix modifier. Technological and economic feasibility study to evaluate expediency of replacing high priced nano-diamonds with nanocrystalline borides and carbides is undertaken.

  17. 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....

  18. Laser Compression of Nanocrystalline Metals

    Science.gov (United States)

    Meyers, M. A.; Jarmakani, H. N.; Bringa, E. M.; Earhart, P.; Remington, B. A.; Vo, N. Q.; Wang, Y. M.

    2009-12-01

    Shock compression in nanocrystalline nickel is simulated over a range of pressures (10-80 GPa) and compared with experimental results. Laser compression carried out at Omega and Janus yields new information on the deformation mechanisms of nanocrystalline Ni. Although conventional deformation does not produce hardening, the extreme regime imparted by laser compression generates an increase in hardness, attributed to the residual dislocations observed in the structure by TEM. An analytical model is applied to predict the critical pressure for the onset of twinning in nanocrystalline nickel. The slip-twinning transition pressure is shifted from 20 GPa, for polycrystalline Ni, to 80 GPa, for Ni with g. s. of 10 nm. Contributions to the net strain from the different mechanisms of plastic deformation (partials, perfect dislocations, twinning, and grain boundary shear) were quantified in the nanocrystalline samples through MD calculations. The effect of release, a phenomenon often neglected in MD simulations, on dislocation behavior was established. A large fraction of the dislocations generated at the front are annihilated.

  19. Superb nanocrystalline alloys for plating

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ With high rigidity and antiwear performance,nanocrystalline metals and their alloys can find wide applications in surface protection.However, the existence of grain boundaries often leads to erosive micro-batteries which accelerate the process of corrosion.Therefore, it has already become a key issue for surface engineering researchers to find nano materials with higher lubricating, anticorrosion and antiwear capacities.

  20. Kinetics of thermal decomposition of CeO2 nanocrystalline precursor prepared by precipitation method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The thermal decomposition of CeO2 nanocrystalline precursor prepared by chemical precipitation method was investigated using thermo-gravimetric/differential scanning calorimetry (TG/DSC) and X-ray powder diffraction (XRD).In particular,the differential thermal analysis curves for the decomposition of CeO2 nanocrystalline precursor were measured at different heating rates in air by a thermal analyzer (NETZSCH STA 449C,Germany).The kinetic parameters of the thermal decomposition of CeO2 nanocrystalline precursor were calculated using the Kissinger method and the Coats-Redfern method.Results show that the apparent active energy E of the reaction is 105.51 kJ/mol,the frequency factor lnA is 3.602 and the reaction order n is 2.This thermal decomposition process can be described by the anti-Jander equation and a threedimensional diffusion mechanism.

  1. Nitriding of high speed steel by bipolar PBII for improvement in adhesion strength of DLC films

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Junho, E-mail: choi@mech.t.u-tokyo.ac.jp [University of Tokyo, Tokyo (Japan); Soejima, Koji; Kato, Takahisa [University of Tokyo, Tokyo (Japan); Kawaguchi, Masahiro [Tokyo Metropolitan Industrial Technology Research Institute (TIRI), Tokyo (Japan); Lee, Wonsik [Korea Institute of Industrial Technology (KITECH), Incheon (Korea, Republic of)

    2012-02-01

    In the present study, bipolar plasma based ion implantation and deposition (bipolar PBII) was used for plasma nitriding of high speed steel (SKH2), and the effects of the treatment parameters (positive pulse voltage, negative pulse voltage, treatment pressure, treatment time, and precursor gases) on the nitriding process were investigated. The hardness, roughness, and depth of nitride layer were also measured. The adhesion strength of diamond-like carbon (DLC) films coated on the nitride substrate was evaluated by carrying out Rockwell indentation and microscratch tests. Nitriding by bipolar PBII was achieved in the combining of two effects: nitrogen ion implantation by applying a high negative pulse voltage and thermal diffusion of nitrogen atoms under the application of a high positive pulse voltage. However, a very high voltage negative pulse caused surface roughening of the nitride layer. Application of a high positive pulse voltage during nitriding was found to be effective in promoting the thermal diffusion of the implanted nitrogen atoms. Effective nitriding could be achieved under the following conditions: high positive pulse voltage, low negative pulse voltage, high nitrogen gas pressure, and addition of hydrogen to the precursor gas. The adhesion strength of the DLC films on the SKH2 substrate was well improved after nitriding.

  2. Nanocrystalline {beta}-sialon by reactive sintering of a SiO{sub 2}-AlN mixture subjected to high-energy ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Tessier, P. [Groupe Minutia, Boucherville, Que. (Canada)]. E-mail: pascal.tessier@airliquide.com; Alamdari, H.D. [Groupe Minutia, Boucherville, Que. (Canada)]. E-mail: alamdari.houshang@nanoxnps.com; Dubuc, R. [Groupe Minutia, Boucherville, Que. (Canada); Boily, S. [Groupe Minutia, Boucherville, Que. (Canada)

    2005-04-05

    A mixture of powders of silica and aluminum nitride is subjected to high-energy ball milling for different milling times. This material is subsequently compacted by uniaxial pressing and sintered at 1450 deg. C. The resulting pellets are crushed and analysed by X-ray diffraction. For short milling times, the amount of phase transformation is minimal and the resulting material mostly consists of cristobalite and aluminum nitride. For long milling times, nanocrystalline {beta}-SiAl{sub 2}O{sub 2}N{sub 2} is mainly produced.

  3. Nitride quantum light sources

    Science.gov (United States)

    Zhu, T.; Oliver, R. A.

    2016-02-01

    Prototype nitride quantum light sources, particularly single-photon emitters, have been successfully demonstrated, despite the challenges inherent in this complex materials system. The large band offsets available between different nitride alloys have allowed device operation at easily accessible temperatures. A wide range of approaches has been explored: not only self-assembled quantum dot growth but also lithographic methods for site-controlled nanostructure formation. All these approaches face common challenges, particularly strong background signals which contaminate the single-photon stream and excessive spectral diffusion of the quantum dot emission wavelength. If these challenges can be successfully overcome, then ongoing rapid progress in the conventional III-V semiconductors provides a roadmap for future progress in the nitrides.

  4. Synthesis of aluminum nitride nanoparticles by a facile urea glass route and influence of urea/metal molar ratio

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Zhifang; Wan, Yizao [School of Materials Science and Engineering, and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300072 (China); Xiong, Guangyao [School of Mechanical and Electrical Engineering, East China Jiaotong University, Nanchang, Jiangxi 330013 (China); Guo, Ruisong [School of Materials Science and Engineering, and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300072 (China); Luo, Honglin, E-mail: hlluo@tju.edu.cn [School of Materials Science and Engineering, and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300072 (China)

    2013-09-01

    Attention toward nanosized aluminum nitride (AlN) was rapidly increasing due to its physical and chemical characteristics. In this work, nanocrystalline AlN particles were prepared via a simple urea glass route. The effect of the urea/metal molar ratio on the crystal structure and morphology of nanocrystalline AlN particles was studied using X-ray powder diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results revealed that the morphology and the crystal structure of AlN nanoparticles could be controlled by adjusting the urea/metal ratio. Furthermore, a mixture of Al{sub 2}O{sub 3} and h-AlN was detected at the urea/metal molar ratio of 4 due to the inadequate urea content. With increasing the molar ratio, the pure h-AlN was obtained. In addition, the nucleation and growth mechanisms of AlN nanocrystalline were proposed.

  5. Deformation Twinning During Nanoindentation of Nanocrystalline Ta

    OpenAIRE

    Wang, Y. M.; Hodge, A. M.; Biener, J.; Hamza, A.V.; Barnes, D E; Liu, Kai; Nieh, T. G.

    2005-01-01

    The deformation mechanism of body-centered cubic (bcc) nanocrystalline tantalum with grain sizes of 10–30 nm is investigated by nanoindentation, scanning electron microscopy and high-resolution transmission electron microscopy. In a deviation from molecular dynamics simulations and existing experimental observations on other bcc nanocrystalline metals, the plastic deformation of nanocrystalline Ta during nanoindentation is controlled by deformation twinning. The observation of multiple twin i...

  6. Development of wear-resistant coatings for cobalt-base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Cockeram, B.V.

    1999-03-01

    The costs and hazards resulting from nuclear plant radiation exposure with activated cobalt wear debris could potentially be reduced by covering the cobalt-base materials with a wear resistant coating. However, the hardnesses of many cobalt-base wear alloys are significantly lower than conventional PVD hard coatings, and mechanical support of the hard coating is a concern. Four approaches have been taken to minimize the hardness differences between the substrate and PVD hard coating: (1) use a thin Cr-nitride hard coating with layers that are graded with respect to hardness, (2) use a thicker, multilayered coating (Cr-nitride or Zr-nitride) with graded layers, (3) use nitriding to harden the alloy subsurface followed by application of a multilayered coating of Cr-nitride, and (4) use of nitriding alone. Since little work has been done on application of PVD hard coatings to cobalt-base alloys, some details on process development and characterization of the coatings is presented. Scratch testing was used to evaluate the adhesion of the different coatings. A bench-top rolling contact test was used to evaluate the wear resistance of the coatings. The test results are discussed, and the more desirable coating approaches are identified.

  7. The rapid nitriding of Al alloys with the controlling of plasma power density and pretreatments

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hyun Jun; Moon, Kyoung Il [Korea Institute of Industrial Technology, Cheonan (Korea, Republic of); Lee, Jae Seung; Choi, Yoon [A-Tech System, Seoul (Korea, Republic of)

    2010-05-15

    The properties of AlN make this material very attractive for optical, electronic, and tribological application. Also, if the AlN could be formed on the Al surface to enhance its surface properties, Al could be applied for the lightening of machine parts. However, a dense oxide film exists on the surface of Al, which prevents the formation of the Al nitride even during plasma nitriding and plasma coating process. In this study, plasma nitriding has been tried to form an AlN layer on Al after the surface activation processes. During the plasma nitriding, the density of the nitrogen ions was amplified by means of controlling the power of the Al substrates. The film thickness, microstructural features and the mechanical properties such as hardness and wear properties of the AlN layer were examined as a function of the process parameters of pretreatment and plasma nitriding

  8. Plasma spray for forming nanostructured thermal barrier coatings

    Institute of Scientific and Technical Information of China (English)

    LIN; Feng; JIANG; Xian-liang; YU; Yue-guang; ZENG; Ke-li; REN; Xian-jing

    2005-01-01

    Nanocrystalline powders of yttrium partially stabilized zirconia (YPSZ) are reprocessed into agglomerated feedstocks for plasma spraying thermal barrier coatings (TBCs), using the methods of ball milling, slurry dispersion, spray drying, and heat treatment. Atmospheric plasma is used to spray the agglomerated nanocrystalline particle feedstocks and coatings were deposited on the substrate of Ni-based superalloy. Scanning electron microscopy (SEM) is used to examine the morphology and cross-section of the agglomerated feedstocks and the free-section and cross-section of the nanostructured TBCs. Experimental results show that the agglomerated nanocrystalline particles are spherical and dense. Unlike conventional plasma-sprayed coatings, the micron/nano/micron sandwich structure can be found in the nanostructured YPSZ coatings deposited by atmospheric plasma spraying.

  9. Method of nitriding, carburizing, or oxidizing refractory metal articles using microwaves

    Science.gov (United States)

    Holcombe, Cressie E.; Dykes, Norman L.; Tiegs, Terry N.

    1992-01-01

    A method of nitriding an article of refractory-nitride-forming metal or metalloids. A consolidated metal or metalloid article is placed inside a microwave oven and nitrogen containing gas is introduced into the microwave oven. The metal or metalloid article is heated to a temperature sufficient to react the metal or metalloid with the nitrogen by applying a microwave energy within the microwave oven. The metal or metalloid article is maintained at that temperature for a period of time sufficient to convert the article of metal or metalloid to an article of refractory nitride. in addition, a method of applying a coating, such as a coating of an oxide, a carbide, or a carbo-nitride, to an article of metal or metalloid by microwave heating.

  10. High Temperature Resistant Zirconia Coating for In-space Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To enhance NASA systems, Spire proposes a novel technique for growing a graded nanocrystalline ZrON/ZrO2 protective coating with superior heat tolerance on relevant...

  11. Application of Nanocrystalline LaNi5-type Hydrogen Absorbing Alloys in Ni-MHx Batteries

    Institute of Scientific and Technical Information of China (English)

    Jurczyk M; Nowak M

    2004-01-01

    The structure and electrochemical properties of nanocrystalline LaNi5-type alloys were studied. These materials were prepared by mechanical alloying (MA) followed by annealing. The properties of hydrogen host materials can be modified substantially by alloying to obtain the desired storage characteristics. It was found that the partial substitution of Ni by Al or Mn in LaNi5-xMx alloy leads to an increase in discharge capacity. The alloying elements such as Al, Mn and Co greatly improved the cycle life of LaNi5 material. For example, in the nanocrystalline LaNi3.75Mn0.75Al0.25Co0.25 powder, discharge capacity up to 258 mAh·g-1 was measured (at 40 mA·g-1 discharge current). Furthermore,the effect of the graphite coating on the structure of some nanocrystalline alloys and the electrodes characteristics were investigated. The mechanical coating with graphite effectively reduced the degradation rate of the studied electrode materials. The combination of a nanocrystalline LaNi5-type hydride electrodes and a nickel positive electrode to form a Ni-MH battery, was successful.

  12. Tensile behavior of nanocrystalline copper

    Energy Technology Data Exchange (ETDEWEB)

    Sanders, P.G.; Weertman, J.R. [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering; Eastman, J.A. [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering]|[Argonne National Lab., IL (United States). Materials Science Div.

    1995-11-01

    High density nanocrystalline copper produced by inert gas condensation was tested in tension. Displacements were measured using foil strain gauges, which greatly improved the accuracy of the strain data. The Young`s modulus of nanocrystalline copper was found to be consistent with that of coarse-grained copper. Total elongations of {approx} 1% were observed in samples with grain sizes less than 50 nm, while a sample with a grain size of 110 nm exhibited more than 10% elongation, perhaps signifying a change to a dislocation-based deformation mechanism in the larger-grained material. In addition, tensile tests were performed as a function of strain rate, with a possible trend of decreased strength and increased elongation as the strain rate was decreased.

  13. Intergranular fracture in nanocrystalline metals

    Science.gov (United States)

    Farkas, D.; van Swygenhoven, H.; Derlet, P. M.

    2002-08-01

    Crack propagation studies in nanocrystalline Ni samples with mean grain sizes ranging from 5 to 12 nm are reported using atomistic simulations. For all grain sizes pure intergranular fracture is observed. Intergranular fracture is shown to proceed by the coalescence of microvoids formed at the grain boundaries ahead of the crack. The energy released during propagation is higher than the Griffith value, indicating an additional grain-boundary accommodation mechanism.

  14. Structure and thermal stability of nanocrystalline materials

    Indian Academy of Sciences (India)

    B S Murty; M K Datta; S K Pabi

    2003-02-01

    Nanocrystalline materials, which are expected to play a key role in the next generation of human civilization, are assembled with nanometre-sized “building blocks” consisting of the crystalline and large volume fractions of intercrystalline components. In order to predict the unique properties of nanocrystalline materials, which are a combination of the properties of the crystalline and intercrystalline regions, it is essential to understand precisely how the structures of crystalline and intercrystalline regions vary with decrease in crystallite size. In addition, study of the thermal stability of nanocrystalline materials against significant grain growth is both scientific and technological interest. A sharp increase in grain size (to micron levels) during consolidation of nanocrystalline powders to obtain fully dense materials may consequently result in the loss of some unique properties of nanocrystalline materials. Therefore, extensive interest has been generated in exploring the size effects on the structure of crystalline and intercrystalline region of nanocrystalline materials, and the thermal stability of nanocrystalline materials against significant grain growth. The present article is aimed at understanding the structure and stability of nanocrystalline materials.

  15. Stress control of heterogeneous nanocrystalline diamond sphere through pressure-temperature tuning

    Science.gov (United States)

    Ding, Wei; Han, Jingjing; Hu, Qiwei; Chen, Yang; Liu, Fangming; Liu, Yinjuan; Gou, Li; He, Duanwei; Zhan, Guodong

    2017-03-01

    The hollow nanocrystalline diamond (NCD) sphere, a promising ablator material for inertial confinement fusion capsule, is generally fabricated by the chemical vapor deposition method. Herein, we report on a method to transform hydrogenated tetrahedral amorphous carbon coatings on spherical molybdenum (Mo) substrates into nanocrystalline diamond films via a designed high pressure high temperature (HPHT) treatment that balances the mismatch in the thermal expansion coefficient between a diamond coating and the Mo substrate through the difference in the bulk modulus. The results show that the density and strength of the diamond shell increase significantly and the residual stress is eliminated as well. The methodology of the designed HPHT treatment can not only provide an alternative way to fabricate NCD spheres but also can apply to other heterogeneous material stress control applications.

  16. Decorating multiwalled carbon nanotubes with zinc oxide nano-crystallines through hydrothermal growth process

    Institute of Scientific and Technical Information of China (English)

    LI ChenSha; QIAO YingJie; LI YuMing

    2012-01-01

    Multiwalled-carbon nanotubes coated with nano-crystalline zinc oxide (ZnO) was prepared by in situ growth of nano zinc oxide on the surfaces of carbon nanotubes through hydrothermal method.X-ray diffraction,transmission electron microscopy and scanning electron microscopy analysis techniques were used to characterize the samples.It was observed that a layer of nano-crystalline ZnO with the wurtzite hexagonal crystal structure was uniformly coated on the nanotube surfaces with good adhesion,which resulted in the formation of a novel ZnO-nanotube nano composite.In this work,the carbon nanotubes decorated by metal oxide nanoparticles were synthesized by a simple chemical-solution route which is suitable for the large-scale production with low cost.

  17. Protective coatings preventing hydrogen desorption from titanium during ion irradiation

    Science.gov (United States)

    Evsin, A. E.; Begrambekov, L. B.; Dovganyuk, S. S.; Kaplevsky, A. S.; Shutikova, M. I.

    2017-05-01

    Effect of yttria and titanium nitride coatings on features of deuterium desorption from titanium layer is investigated. It is shown that both coatings significantly raise the temperature of maximum of deuterium thermal desorption from titanium under linear heating and prevent desorption under prolonged keeping at the operating temperature of a neutron tube target. However, under irradiation with ions of H2 + O2 plasma the barrier properties of titanium nitride appear to degrade.

  18. CHARACTERIZATION AND PERFORMANCE OF DUPLEX-COATINGS ON Cr-V COLD WORK TOOL STEEL

    Directory of Open Access Journals (Sweden)

    Peter Jurči

    2015-09-01

    Full Text Available Specimens made of Vanadis 6 steel were heat treated, plasma nitrided and coated with Cr2N. The microstructure, phase constitution and mechanical properties of plasma nitrided areas and duplex-coatings have been investigated using the light microscopy, scanning electron microscopy, X-ray diffraction and microhardness measurements. The adhesion of the coatings and the wear performance were studied using the scratch test and ring-on-plate tribological testing. Worn surfaces were examined by scanning electron microscopy. Nitrided areas formed at lower temperature were free of compound “white” layer while hose developed at higher temperatures contained as the white layer so the nitrided network. Significant increase in substrate hardness was detected due to the nitriding. Beneficial effect of the nitriding on the adhesion of Cr2N coatings was clearly determined whereas the extent in improvement of the adhesion depends on the presence/no presence of “white” layer on the surface. The extent of beneficial effect of plasma nitriding on the wear performance follows the impact of the constitution of nitrided areas on the adhesion. The amelioration of wear performance of Cr2N coatings can be attributed to the supporting effect of hard nitrided intermediate region, which provides excellent resistance of the substrate against plastic deformation, under heavy loading in particular. Practical testing demonstrated many times prolonged service-time of duplex-treated tools for sheet metal working.

  19. Evaluation of silicon nitride as a substrate for culture of PC12 cells: an interfacial model for functional studies in neurons.

    Directory of Open Access Journals (Sweden)

    Johan Jaime Medina Benavente

    Full Text Available Silicon nitride is a biocompatible material that is currently used as an interfacial surface between cells and large-scale integration devices incorporating ion-sensitive field-effect transistor technology. Here, we investigated whether a poly-L-lysine coated silicon nitride surface is suitable for the culture of PC12 cells, which are widely used as a model for neural differentiation, and we characterized their interaction based on cell behavior when seeded on the tested material. The coated surface was first examined in terms of wettability and topography using contact angle measurements and atomic force microscopy and then, conditioned silicon nitride surface was used as the substrate for the study of PC12 cell culture properties. We found that coating silicon nitride with poly-L-lysine increased surface hydrophilicity and that exposing this coated surface to an extracellular aqueous environment gradually decreased its roughness. When PC12 cells were cultured on a coated silicon nitride surface, adhesion and spreading were facilitated, and the cells showed enhanced morphological differentiation compared to those cultured on a plastic culture dish. A bromodeoxyuridine assay demonstrated that, on the coated silicon nitride surface, higher proportions of cells left the cell cycle, remained in a quiescent state and had longer survival times. Therefore, our study of the interaction of the silicon nitride surface with PC12 cells provides important information for the production of devices that need to have optimal cell culture-supporting properties in order to be used in the study of neuronal functions.

  20. 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.

  1. Metamaterial Coatings for Broadband Asymmetric Mirrors

    CERN Document Server

    Chen, A; Hasegawa, K; Podolskiy, V A; Chen, Aiqing; Deutsch, Miriam; Hasegawa, Keisuke; Podolskiy, Viktor A.

    2006-01-01

    We report on design and fabrication of nano-composite metal-dielectric thin film coatings with high reflectance asymmetries. Applying basic dispersion engineering principles to model a broadband and large reflectance asymmetry, we obtain a model dielectric function for the metamaterial film, closely resembling the effective permittivity of disordered metal-dielectric nano-composites. Coatings realized using disordered nanocrystalline silver films deposited on glass substrates confirm the theoretical predictions, exhibiting symmetric transmittance, large reflectance asymmetries and a unique flat reflectance asymmetry.

  2. 太阳能多晶硅铸锭用石英坩埚氮化硅涂层的免烧工艺%Unfired Process for Silicon Nitride Coating of Quartz Crucible for Solar Poly-silicon Ingots

    Institute of Scientific and Technical Information of China (English)

    周艳华

    2012-01-01

    An unfired process is introduced for the spraying crucible during the production process for the solar poly- silicon ingots. Namely a little water soluble organic matter is added into the silicon nitride slurry(The water soluble organic matter is adhesive, damp-proof agent, dispersant),and then the silicon nitride powder is forcefully adsorbed on the inner wall of the crucible by the chemical adsorption of organic macromolecule and the physical absorption of silicon nitride. Compared to the traditional process which calcinates the spraying crucible at 1050℃ for 21 hours, this process can shorten production cycle, raise production efficiency and economize production cost.%本文介绍一种太阳能多晶硅片生产过程中,喷涂坩蜗免焙烧的工艺,即在氮化硅浆料中加入少许水溶性有机物(粘结剂、防潮剂、分散剂),通过有机高分子的化学吸附和氮化硅粉的物理吸附作用使氮化硅粉强有力地吸附在坩埚内壁,免去了传统工艺中喷涂坩蜗在坩蜗烧结炉中焙烧21h,焙烧温度为1050℃的工艺。与传统工艺相比,此工艺缩短硅片生产周期,提高生产效率,降低生产成本。

  3. Method to produce catalytically active nanocomposite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, Ali; Eryilmaz, Osman Levent; Urgen, Mustafa; Kazmanli, Kursat

    2016-02-09

    A nanocomposite coating and method of making and using the coating. The nanocomposite coating is disposed on a base material, such as a metal or ceramic; and the nanocomposite consists essentially of a matrix of an alloy selected from the group of Cu, Ni, Pd, Pt and Re which are catalytically active for cracking of carbon bonds in oils and greases and a grain structure selected from the group of borides, carbides and nitrides.

  4. Analysis of plasma nitrided steels

    Science.gov (United States)

    Salik, J.; Ferrante, J.; Honecy, F.; Hoffman, R., Jr.

    1987-01-01

    The analysis of plasma nitrided steels can be divided to two main categories - structural and chemical. Structural analysis can provide information not only on the hardening mechanisms but also on the fundamental processes involved. Chemical analysis can be used to study the kinetics for the nitriding process and its mechanisms. In this paper preliminary results obtained by several techniques of both categories are presented and the applicability of those techniques to the analysis of plasma-nitrided steels is discussed.

  5. Caracterisation of Titanium Nitride Layers Deposited by Reactive Plasma Spraying

    Science.gov (United States)

    Roşu, Radu Alexandru; Şerban, Viorel-Aurel; Bucur, Alexandra Ioana; Popescu, Mihaela; Uţu, Dragoş

    2011-01-01

    Forming and cutting tools are subjected to the intense wear solicitations. Usually, they are either subject to superficial heat treatments or are covered with various materials with high mechanical properties. In recent years, thermal spraying is used increasingly in engineering area because of the large range of materials that can be used for the coatings. Titanium nitride is a ceramic material with high hardness which is used to cover the cutting tools increasing their lifetime. The paper presents the results obtained after deposition of titanium nitride layers by reactive plasma spraying (RPS). As deposition material was used titanium powder and as substratum was used titanium alloy (Ti6Al4V). Macroscopic and microscopic (scanning electron microscopy) images of the deposited layers and the X ray diffraction of the coatings are presented. Demonstration program with layers deposited with thickness between 68,5 and 81,4 μm has been achieved and presented.

  6. Preferential orientation in metal nitride deposited by the UBM system

    Directory of Open Access Journals (Sweden)

    Jhon Jairo Olaya

    2010-05-01

    Full Text Available This work was aimed at studying the influence of ion bombardment on the preferred orientation (OP of transition metal nitrides (TMN produced by the reactive sputtering technique with a variable unbalanced magnetron through permanent magnets. Tita- nium nitride (TiN coatings were thus studied by varying two parameters: ion-atom ratio on the substrate (Ji/Ja and nitrogen flux. Deposition conditions were as follows: 7 mTorr working pressure, ~ 380ºC substrate temperature, 2 and 8.5 sccm nitrogen flux and 245-265 discharge power. The results showed that preferred orientation (111 and the crystalline behaviour of the produced coatings depended more on nitrogen flux than on ion bombardment. Similarly, micro-hardness measured on films deposited on steel AISI-M2 substrates increased from 1600 to 2000 HV0.025 when nitrogen flux was increased.

  7. Optical properties of nanocrystalline-coated Y{sub 2}O{sub 3}:Er{sup 3+}, Yb{sup 3+} obtained by mechano-chemical and combustion synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Martin-Rodriguez, R., E-mail: rosa.martin@unican.e [Dpto. de Fisica Aplicada, Universidad de Cantabria, Santander 39005 (Spain); Valiente, R. [Dpto. de Fisica Aplicada, Universidad de Cantabria, Santander 39005 (Spain); Pesquera, C.; Gonzalez, F.; Blanco, C. [Dpto. de Ingenieria Quimica y Quimica Inorganica, Univ. de Cantabria, Santander 39005 (Spain); Potin, V.; Marco de Lucas, M.C. [Institut Carnot de Bourgogne, UMR 5209 CNRS-Universite de Bourgogne, BP 47 870, F-21078 Dijon Cedex (France)

    2009-09-15

    Y{sub 2}O{sub 3}:Er{sup 3+}, Yb{sup 3+} nanocrystals have been obtained by ball milling and using a combustion synthesis procedure. In both cases the nanocrystals have been successfully coated with SiO{sub 2} following the Stoeber method. The average size of the as-synthesized nanoparticles has been estimated from X-ray diffraction patterns and transmission electron microscopy images. The dependence of the optical properties of these samples on synthesis procedure or dopant concentration has been investigated. Emission, excitation and lifetime measurements have been carried out. Upconversion luminescence has been detected in all samples and an enhancement of the red to green emission ratio has been observed in all samples after infrared compared to visible excitation. The mechanisms responsible for the upconversion phenomena have been discussed.

  8. Solvothermal preparation of nanocrystalline anatase containing TiO{sub 2} and TiO{sub 2}/SiO{sub 2} coating agents for application of photocatalytic treatments

    Energy Technology Data Exchange (ETDEWEB)

    Mahltig, B., E-mail: boris.mahltig@hs-niederrhein.de [University of Applied Sciences Niederrhein, Faculty of Textile and Clothing Technology, Webschulstrasse 31, D-41065 Moenchengladbach (Germany); Gesellschaft zur Foerderung von Medizin-, Bio- und Umwelttechnologien e.V., GMBU e.V., Postfach 520165, D-01317 Dresden (Germany); Gutmann, E. [Technische Universitaet Dresden, Institut fuer Strukturphysik, D-01062 Dresden (Germany); Meyer, D.C. [Technische Universitaet Dresden, Institut fuer Strukturphysik, D-01062 Dresden (Germany); Technische Universitaet Bergakademie Freiberg, Institut fuer Experimentelle Physik, D-09596 Freiberg (Germany)

    2011-05-16

    Research highlights: {yields} TiO{sub 2} and TiO{sub 2}/SiO{sub 2} materials prepared by a solvothermal sol-gel process. {yields} Photodecomposition with oxygen increases with increasing solvothermal process temperature. {yields} In presence of H{sub 2}O{sub 2} the dye decomposition is observed even without UV light illumination. {yields} The materials contain potential for cleaning waste water containing dye stuffs. - Abstract: This paper reports on TiO{sub 2} and TiO{sub 2}/SiO{sub 2} materials prepared by a sol-gel process under solvothermal conditions with process temperatures between 120 deg. C and 180 deg. C. Under the preparation conditions chosen, the formation of anatase crystallites starts at a process temperature of 160 deg. C, as observed by X-ray diffraction. From TiO{sub 2} and TiO{sub 2}/SiO{sub 2} sols coatings on viscose fabrics and powders have been prepared. The photoactivity of both materials - coated textiles and powders - is determined by the decomposition of the dye AcidOrange under UV light illumination. Significant dye decomposition is only observed for samples containing a high ratio of TiO{sub 2} and that are solvothermally prepared at 180 deg. C. In contrast, when the photoactivity is determined in presence of H{sub 2}O{sub 2} totally different results are obtained and the degree of AcidOrange decomposition is higher for most of the samples. Furthermore, in presence of H{sub 2}O{sub 2} the dye decomposition is observed even without UV light illumination. Especially samples prepared with the polymer Pluronic P123 under lower solvothermal process temperatures exhibit strong dye decomposition without illumination in presence of H{sub 2}O{sub 2}. Therefore, these materials could be of high interest for cleaning waste water containing dye stuffs from textile industry.

  9. Fatigue modelling for gas nitriding

    Directory of Open Access Journals (Sweden)

    H. Weil

    2016-10-01

    Full Text Available The present study aims to develop an algorithm able to predict the fatigue lifetime of nitrided steels. Linear multi-axial fatigue criteria are used to take into account the gradients of mechanical properties provided by the nitriding process. Simulations on rotating bending fatigue specimens are made in order to test the nitrided surfaces. The fatigue model is applied to the cyclic loading of a gear from a simulation using the finite element software Ansys. Results show the positive contributions of nitriding on the fatigue strength

  10. High temperature resistant cermet and ceramic compositions. [for thermal resistant insulators and refractory coatings

    Science.gov (United States)

    Phillips, W. M. (Inventor)

    1978-01-01

    High temperature oxidation resistance, high hardness and high abrasion and wear resistance are properties of cermet compositions particularly to provide high temperature resistant refractory coatings on metal substrates, for use as electrical insulation seals for thermionic converters. The compositions comprise a sintered body of particles of a high temperature resistant metal or metal alloy, preferably molybdenum or tungsten particles, dispersed in and bonded to a solid solution formed of aluminum oxide and silicon nitride, and particularly a ternary solid solution formed of a mixture of aluminum oxide, silicon nitride and aluminum nitride. Ceramic compositions comprising a sintered solid solution of aluminum oxide, silicon nitride and aluminum nitride are also described.

  11. Fabrication of aluminum nitride and its stability in liquid alkali metals

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Rink, D.L. [Argonne National Lab., Chicago, IL (United States)

    1995-04-01

    The objective of this task are to (a) evaluate several fabrication procedures for development of aluminum nitride (AlN) coatings on the candidate first-wall structural material V-5wt.%Cr-5wt.%Ti, (b) evaluate the stability of coatings in contact with the structural alloy and liquid Li at temperatures of 200 to 400{degrees}C, (c) measure the electrical resistivity of the coated films after exposure to liquid Li, (d) evaluate the effects of coating defects on electrical resistivity, and (e) establish in-situ repair procedures to maintain adequate electrical insulating properties for the coatings.

  12. Engineered CVD Diamond Coatings for Machining and Tribological Applications

    Science.gov (United States)

    Dumpala, Ravikumar; Chandran, Maneesh; Ramachandra Rao, M. S.

    2015-07-01

    Diamond is an allotropes of carbon and is unique because of its extreme hardness (~100 GPa), low friction coefficient (fracture toughness can be tuned by controlling the grain size of the coatings from a few microns to a few nanometers. In this review, characteristics and performance of the CVD diamond coatings deposited on cemented tungsten carbide (WC-Co) substrates were discussed with an emphasis on WC-Co grade selection, substrate pretreatment, nanocrystallinity and microcrystallinity of the coating, mechanical and tribological characteristics, coating architecture, and interfacial adhesion integrity. Engineered coating substrate architecture is essential for CVD diamond coatings to perform well under harsh and highly abrasive machining and tribological conditions.

  13. Hardening Roll Surface by Plasma Nitriding with Subsequent Hardfacing

    Science.gov (United States)

    Pesin, A.; Pustovoytov, D.; Vafin, R.; Yagafarov, I.; Vardanyan, E.

    2017-05-01

    The wear of the surface layer of rolls after ion nitriding in glow discharge, followed by a coating of TiN -TiAlN plasma arc are studied and simulated. stress-strain state of the material rolls under asymmetric rolling with ultra-high shear deformations is simulated. The effect of thermal fields, formed upon contact of the tool and a deformable sheet, the structure of aluminum alloys, are considered.

  14. Deposition of titanium nitride layers by electric arc - Reactive plasma spraying method

    Energy Technology Data Exchange (ETDEWEB)

    Serban, Viorel-Aurel [University ' Politehnica' of Timisoara, Faculty of Mechanical Engineering, No. 1 Mihai Viteazu Boulevard, 300222 Timisoara (Romania); Rosu, Radu Alexandru, E-mail: raduniz@gmail.com [University ' Politehnica' of Timisoara, Faculty of Mechanical Engineering, No. 1 Mihai Viteazu Boulevard, 300222 Timisoara (Romania); Bucur, Alexandra Ioana [National Institute for Research and Development in Electrochemistry and Condensed Matter Timisoara, Analysis and Characterization Department, No. 1 P Andronescu Street, Timisoara 300224 (Romania); Pascu, Doru Romulus [Romania National Research and Development Institute for Welding and Material Testing Timisoara, No. 30 Mihai Viteazu Boulevard, 300222 Timisoara (Romania)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Titanium nitride layers deposited by electric arc - reactive plasma spraying method. Black-Right-Pointing-Pointer Deposition of titanium nitride layers on C45 steel at different spraying distances. Black-Right-Pointing-Pointer Characterization of the coatings hardness as function of the spraying distances. Black-Right-Pointing-Pointer Determination of the corrosion behavior of titanium nitride layers obtained. - Abstract: Titanium nitride (TiN) is a ceramic material which possesses high mechanical properties, being often used in order to cover cutting tools, thus increasing their lifetime, and also for covering components which are working in corrosive environments. The paper presents the experimental results on deposition of titanium nitride coatings by a new combined method (reactive plasma spraying and electric arc thermal spraying). In this way the advantages of each method in part are combined, obtaining improved quality coatings in the same time achieving high productivity. Commercially pure titanium wire and C45 steel as substrate were used for experiments. X-ray diffraction analysis shows that the deposited coatings are composed of titanium nitride (TiN, Ti{sub 2}N) and small amounts of Ti{sub 3}O. The microstructure of the deposited layers, investigated both by optical and scanning electron microscopy, shows that the coatings are dense, compact, without cracks and with low porosity. Vickers microhardness of the coatings presents maximum values of 912 HV0.1. The corrosion tests in 3%NaCl solution show that the deposited layers have a high corrosion resistance compared to unalloyed steel substrate.

  15. Titanium Nitride Cermets

    Science.gov (United States)

    1952-07-01

    C ermets 7 Effect of Amount of Metal on Strength of TiN-Ni-Cr....26 Cerme ts S Effect of Amount of Metal on Strength of TiN-Co-Cr....27 Cermets 9...Figures 7 and 8. Titanium Nitride-Nickel-Chromium Cerme ts From Figure 7, it can be seen that 2900OF was the better firing temperature. The 20% metal

  16. Effect of annealing temperature on oxygen vacancy concentrations of nanocrystalline CeO{sub 2} film

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ka; Chang, Yongqin, E-mail: chang@ustb.edu.cn; Lv, Liang; Long, Yi

    2015-10-01

    Highlights: • Nanocrystalline CeO{sub 2} films were prepared by a facile sol–gel spin coating method. • Oxygen vacancy concentrations can be controlled by annealing temperatures. • The films show perfect thermal stability at various annealing temperatures. • PL, XPS and Raman spectra are obviously affected by oxygen vacancy concentrations. - Abstract: Nanocrystalline CeO{sub 2} films with around 250 nm thickness were deposited on Si (0 0 1) substrates by a facile sol–gel process with spin coating method. The films are of cubic fluorite structure, and some lattice distortions exist in the film. The phase stability and small change in lattice parameter at different annealing temperatures indicate the good thermal stability of the nanocrystalline CeO{sub 2} films. The average grain-size and surface roughness of the films increase with the increase of annealing temperature. The content of Ce{sup 3+} and oxygen vacancy is very high in the nanocrystalline CeO{sub 2} films, while, the films still remain cubic phase regardless of its high level non-stoichiometric composition. All the annealed samples show two emission bands, and the defect peak centered at ∼500 nm shows a red-shift. The intensity of the green-emission band increases with the increasing annealing temperature, which might result from the increasing concentration of oxygen vacancies caused by the valence transition from Ce{sup 4+} to Ce{sup 3+}, and it has also been confirmed by the X-ray photoelectron spectroscopy results. This work demonstrates that oxygen vacancy plays an important role on the properties of the nanocrystalline CeO{sub 2} film, and it also provides a possible way to control the concentration of oxygen vacancies.

  17. Coating for components requiring hydrogen peroxide compatibility

    Science.gov (United States)

    Yousefiani, Ali (Inventor)

    2010-01-01

    The present invention provides a heretofore-unknown use for zirconium nitride as a hydrogen peroxide compatible protective coating that was discovered to be useful to protect components that catalyze the decomposition of hydrogen peroxide or corrode when exposed to hydrogen peroxide. A zirconium nitride coating of the invention may be applied to a variety of substrates (e.g., metals) using art-recognized techniques, such as plasma vapor deposition. The present invention further provides components and articles of manufacture having hydrogen peroxide compatibility, particularly components for use in aerospace and industrial manufacturing applications. The zirconium nitride barrier coating of the invention provides protection from corrosion by reaction with hydrogen peroxide, as well as prevention of hydrogen peroxide decomposition.

  18. Plasmonic Titanium Nitride Nanostructures via Nitridation of Nanopatterned Titanium Dioxide

    DEFF Research Database (Denmark)

    Guler, Urcan; Zemlyanov, Dmitry; Kim, Jongbum

    2017-01-01

    Plasmonic titanium nitride nanostructures are obtained via nitridation of titanium dioxide. Nanoparticles acquired a cubic shape with sharper edges following the rock-salt crystalline structure of TiN. Lattice constant of the resulting TiN nanoparticles matched well with the tabulated data. Energ...

  19. The modified nanocrystalline cellulose for hydrophobic drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Qing, Weixia [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004 (China); Medical College, Henan University, Kaifeng 475004 (China); Wang, Yong [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004 (China); Wang, Youyou [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004 (China); Key Lab of Natural Medicine and Immun-engineering of Henan Province, Henan University, Kaifeng 475004 (China); Zhao, Dongbao [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004 (China); Liu, Xiuhua, E-mail: ll514527@163.com [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004 (China); Key Lab of Natural Medicine and Immun-engineering of Henan Province, Henan University, Kaifeng 475004 (China); Zhu, Jinhua [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004 (China)

    2016-03-15

    Graphical abstract: - Highlights: • Torispherical NCC was synthesized through the improvements on the hydrolysis method. • NCC was firstly modified with CTMAB as a drug carrier. • Luteolin and luteoloside loading CTMAB-coated NCC were studied. - Abstract: In this work, torispherical nanocrystalline cellulose (NCC) was synthesized, and firstly modified with a cationic surfactant cetyltrimethylammonium bromide (CTMAB). It was proved that the kinetics of NCC adsorbing CTMAB followed the pseudo-second-order kinetics equation, and the adsorption isotherm model followed Freundlich which was multi molecular layer adsorption model. The morphology and structure of NCC and CTMAB-coated NCC were characterized by transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). Stabilities of NCC and CTMAB-coated NCC were assayed by zeta potential. The results showed that NCC in CTMAB solution was well-dispersed and stable. Moreover, the drug loading and release performance of CTMAB-coated NCC were studied using luteolin (LUT) and luteoloside (LUS) as model drugs.

  20. Bulk nano-crystalline alloys

    OpenAIRE

    T.-S. Chin; Lin, C. Y.; Lee, M.C.; R.T. Huang; S. M. Huang

    2009-01-01

    Bulk metallic glasses (BMGs) Fe–B–Y–Nb–Cu, 2 mm in diameter, were successfully annealed to become bulk nano-crystalline alloys (BNCAs) with α-Fe crystallite 11–13 nm in size. A ‘crystallization-and-stop’ model was proposed to explain this behavior. Following this model, alloy-design criteria were elucidated and confirmed successful on another Fe-based BMG Fe–B–Si–Nb–Cu, 1 mm in diameter, with crystallite sizes 10–40 nm. It was concluded that BNCAs can be designed in general by the proposed cr...

  1. Development of wear-resistant coatings for cobalt-base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Cockeram, B.V.

    1999-10-22

    The level of nuclear plant radiation exposure due to activated cobalt wear debris could potentially be reduced by covering the cobalt-base materials with a wear resistant coating. Laboratory pin-on-disc and rolling contact wear tests were used to evaluate the wear performance of several coatings. Based on the results of these tests, multilayer Cr-nitride coatings and ion nitriding are the most promising approaches.

  2. Multipactor suppressing titanium nitride thin films analyzed through XPS and AES

    Energy Technology Data Exchange (ETDEWEB)

    Castro C, M.; Durrer, W.; Lopez, J. A.; Pinales, L. A. [Physics Department, University of Texas, El Paso TX 79968 (United States); Encinas B, C.; Moller, D. [Centro de Investigacion en Materiales Avanzados S. C., Miguel de Cervantes Saavedra 120, Complejo Industrial Chihuahua, 31109 Chihuahua (Mexico)

    2008-02-15

    Cathodic-magnetron-deposited titanium nitride films were grown on anodized aluminum substrates and studied via AES and XPS spectroscopies to determine their depth-dependence composition. As it is well known, the native oxide grown on aluminum does not make the substrate impervious to radio frequency damage, and typically a thin film coating is needed to suppress substrate damage. In this article we present the profile composition of titanium nitride films, used as a protective coating for aluminum, that underwent prior conditioning through anodization, observed after successive sputtering stages. (Author)

  3. Alternative Liquid Fuel Effects on Cooled Silicon Nitride Marine Gas Turbine Airfoils

    Energy Technology Data Exchange (ETDEWEB)

    Holowczak, J.

    2002-03-01

    With prior support from the Office of Naval Research, DARPA, and U.S. Department of Energy, United Technologies is developing and engine environment testing what we believe to be the first internally cooled silicon nitride ceramic turbine vane in the United States. The vanes are being developed for the FT8, an aeroderivative stationary/marine gas turbine. The current effort resulted in further manufacturing and development and prototyping by two U.S. based gas turbine grade silicon nitride component manufacturers, preliminary development of both alumina, and YTRIA based environmental barrier coatings (EBC's) and testing or ceramic vanes with an EBC coating.

  4. Gallium nitride electronics

    Science.gov (United States)

    Rajan, Siddharth; Jena, Debdeep

    2013-07-01

    In the past two decades, there has been increasing research and industrial activity in the area of gallium nitride (GaN) electronics, stimulated first by the successful demonstration of GaN LEDs. While the promise of wide band gap semiconductors for power electronics was recognized many years before this by one of the contributors to this issue (J Baliga), the success in the area of LEDs acted as a catalyst. It set the field of GaN electronics in motion, and today the technology is improving the performance of several applications including RF cell phone base stations and military radar. GaN could also play a very important role in reducing worldwide energy consumption by enabling high efficiency compact power converters operating at high voltages and lower frequencies. While GaN electronics is a rapidly evolving area with active research worldwide, this special issue provides an opportunity to capture some of the great advances that have been made in the last 15 years. The issue begins with a section on epitaxy and processing, followed by an overview of high-frequency HEMTs, which have been the most commercially successful application of III-nitride electronics to date. This is followed by review and research articles on power-switching transistors, which are currently of great interest to the III-nitride community. A section of this issue is devoted to the reliability of III-nitride devices, an area that is of increasing significance as the research focus has moved from not just high performance but also production-worthiness and long-term usage of these devices. Finally, a group of papers on new and relatively less studied ideas for III-nitride electronics, such as interband tunneling, heterojunction bipolar transistors, and high-temperature electronics is included. These areas point to new areas of research and technological innovation going beyond the state of the art into the future. We hope that the breadth and quality of articles in this issue will make it

  5. Low-temperature deposition of crystalline silicon nitride nanoparticles by hot-wire chemical vapor deposition

    Science.gov (United States)

    Kim, Chan-Soo; Youn, Woong-Kyu; Lee, Dong-Kwon; Seol, Kwang-Soo; Hwang, Nong-Moon

    2009-07-01

    The nanocrystalline alpha silicon nitride (α-Si 3N 4) was deposited on a silicon substrate by hot-wire chemical vapor deposition at the substrate temperature of 700 °C under 4 and 40 Torr at the wire temperatures of 1430 and 1730 °C, with a gas mixture of SiH 4 and NH 3. The size and density of crystalline nanoparticles on the substrate increased with increasing wire temperature. With increasing reactor pressure, the crystallinity of α-Si 3N 4 nanoparticles increased, but the deposition rate decreased.

  6. Influences of the iron ion (Fe{sup 3+})-doping on structural and optical properties of nanocrystalline TiO{sub 2} thin films prepared by sol-gel spin coating

    Energy Technology Data Exchange (ETDEWEB)

    Ben Naceur, J. [Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche des Sciences et Technologies de l' Energie, BP.95, Hammam-Lif 2050 (Tunisia); Mechiakh, R., E-mail: raouf_mechiakh@yahoo.fr [Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche des Sciences et Technologies de l' Energie, BP.95, Hammam-Lif 2050 (Tunisia); Departement de Medecine, Faculte de Medecine, Universite Hadj Lakhdar, Batna (Algeria); Bousbih, F.; Chtourou, R. [Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche des Sciences et Technologies de l' Energie, BP.95, Hammam-Lif 2050 (Tunisia)

    2011-10-01

    Titanium dioxide (TiO{sub 2}) thin films doping of various iron ion (Fe{sup 3+}) concentrations were deposited on silicon (Si) (100) and quartz substrates by sol-gel Spin Coating technique followed by a thermal treatment at 600 deg. C. The structure, surface morphology and optical properties, as a function of the doping, have been studied by X-ray diffractometer (XRD), Raman, ultraviolet-visible (UV-vis) and Spectroscopic Ellipsometry (SE). XRD and Raman analyzes of our thin films show that the crystalline phase of TiO{sub 2} thin films comprised only the anatase TiO{sub 2}, but the crystallinity decreased when the Fe{sup 3+} content increased from 0% to 20%. During the Fe{sup 3+} addition to 20%, the phase of TiO{sub 2} thin film still maintained the amorphous state. The grain size calculated from XRD patterns varies from 29.3 to 22.6 nm. The complex index and the optical band gap (E{sub g}) of the films were determined by the spectroscopic ellipsometry analysis. We have found that the optical band gap decreased with an increasing Fe{sup 3+} content.

  7. Direct Laser Synthesis of Functional Coatings

    Energy Technology Data Exchange (ETDEWEB)

    P. Schaaf; Michelle D. Shinn; E. Carpene; J. Kaspar

    2005-06-01

    The direct laser synthesis of functional coatings employs the irradiation of materials with short intensive laser pulses in a reactive atmosphere. The material is heated and plasma is ignited in the reactive atmosphere. This leads to an intensive interaction of the material with the reactive species and a coating is directly formed on the materials surface. By that functional coatings can be easily produced a fast way on steel, aluminium, and silicon by irradiation in nitrogen, methane, or even hydrogen. The influence of the processing parameters to the properties of the functional coatings will be presented for titanium nitride coating produced on titanium with the free electron laser.

  8. Corrosion resistance of monolayer hexagonal boron nitride on copper

    Science.gov (United States)

    Mahvash, F.; Eissa, S.; Bordjiba, T.; Tavares, A. C.; Szkopek, T.; Siaj, M.

    2017-02-01

    Hexagonal boron nitride (hBN) is a layered material with high thermal and chemical stability ideal for ultrathin corrosion resistant coatings. Here, we report the corrosion resistance of Cu with hBN grown by chemical vapor deposition (CVD). Cyclic voltammetry measurements reveal that hBN layers inhibit Cu corrosion and oxygen reduction. We find that CVD grown hBN reduces the Cu corrosion rate by one order of magnitude compared to bare Cu, suggesting that this ultrathin layer can be employed as an atomically thin corrosion-inhibition coating.

  9. Nanocrystalline SnO2:F Thin Films for Liquid Petroleum Gas Sensors

    OpenAIRE

    Sutichai Chaisitsak

    2011-01-01

    This paper reports the improvement in the sensing performance of nanocrystalline SnO2-based liquid petroleum gas (LPG) sensors by doping with fluorine (F). Un-doped and F-doped tin oxide films were prepared on glass substrates by the dip-coating technique using a layer-by-layer deposition cycle (alternating between dip-coating a thin layer followed by a drying in air after each new layer). The results showed that this technique is superior to the conventional technique for both improving the ...

  10. Ceramic fiber coatings development and demonstration. Final technical report, 1 July 1989-31 May 1993

    Energy Technology Data Exchange (ETDEWEB)

    Streckert, H.; Hazlebeck, D.; Montgomery, F.; Norton, K.; Schneir, I.

    1993-05-28

    The objective of this program was to develop fiber coating techniques by gas phase and liquid phase processes for interface control in ceramic matrix and metal matrix composites. Thermochemical evaluations of fiber/coating/matrix systems were performed theoretically and experimentally. Liquid phase processes were developed mainly for oxide coatings. Gas phase processes were developed for-carbide, nitride and boride coatings. Coatings were produced on continuous fiber tows and woven fabric. A small scale continuous fabric coater was designed and constructed. Coated fiber tows were infiltrated with silicon nitride matrix by chemical vapor deposition in order to study fiber matrix interactions. Composite coupons were made from Nicalon cloth and infiltrated with silicon nitride. Samples coated with high temperature BN showed flexural strengths up to 350 MPa.... Ceramic Fiber Coating, Chemical Vapor Deposition, Sol-Gel Ceramic Matrix Composites, Metal Matrix Composites.

  11. Platinum nitride with fluorite structure

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Rong; Zhang, Xiao-Feng

    2005-01-31

    The mechanical stability of platinum nitride has been studied using first-principles calculations. By calculating the single-crystal elastic constants, we show that platinum nitride can be stabilized in the fluorite structure, in which the nitrogen atoms occupy all the tetrahedral interstitial sites of the metal lattice. The stability is attributed to the pseudogap effect from analysis of the electronic structure.

  12. 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

  13. Electrochemical nitridation of metal surfaces

    Science.gov (United States)

    Wang, Heli; Turner, John A.

    2015-06-30

    Electrochemical nitridation of metals and the produced metals are disclosed. An exemplary method of electrochemical nitridation of metals comprises providing an electrochemical solution at low temperature. The method also comprises providing a three-electrode potentiostat system. The method also comprises stabilizing the three-electrode potentiostat system at open circuit potential. The method also comprises applying a cathodic potential to a metal.

  14. Structure and properties of hard and superhard Zr-Cu-N nanocomposite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Zeman, P.; Cerstvy, R.; Musil, J. [Univ. of West Bohemia, Plzen (Czech Republic). Dept. of Phys.; Mayrhofer, P.H.; Mitterer, C. [Institut fuer Metallkunde und Werkstoffpruefung, Montanuniversitaet, Franz-Josef-Strasse 18, A-8700, Leoben (Austria)

    2000-09-30

    Zr-Cu-N nanocomposite films represent a new material of the type-nanocrystalline transition metal nitride (nc-MeN)/metal. In the present work, films were deposited onto steel substrates using unbalanced dc reactive magnetron sputtering of a Zr-Cu (62/38 at.%) target. Film structure, chemical composition, mechanical and optical properties were investigated by means of X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, wavelength dispersive electron probe microanalysis, depth-sensing microindentation and spectroscopic ellipsometry. It was found that (i) there is a strong correlation between the film structure, Cu content and film properties and (ii) either hard or superhard Zr-Cu-N films can be formed. The superhard coatings with hardness H>40 GPa are characterized by a columnar structure, a strong 111 XRD peak from ZrN grains and no diffraction peaks from Cu. These films exhibit a high elastic recovery of about 80% and contain a very low amount of Cu, approximately 1-2 at.%. In contrast, the hard (<40 GPa) Zr-Cu-N films are characterized by many diffraction peaks from polyoriented ZrN and Cu grains, a more random microstructure and a Cu content higher than 2 at.%. The optical properties of nanocomposite Zr-Cu-N films depend on the stoichiometry of the hard ZrN{sub x} compound and the content of Cu in the film. (orig.)

  15. Method to grow pure nanocrystalline diamond films at low temperatures and high deposition rates

    Science.gov (United States)

    Carlisle, John A.; Gruen, Dieter M.; Auciello, Orlando; Xiao, Xingcheng

    2009-07-07

    A method of depositing nanocrystalline diamond film on a substrate at a rate of not less than about 0.2 microns/hour at a substrate temperature less than about 500.degree. C. The method includes seeding the substrate surface with nanocrystalline diamond powder to an areal density of not less than about 10.sup.10sites/cm.sup.2, and contacting the seeded substrate surface with a gas of about 99% by volume of an inert gas other than helium and about 1% by volume of methane or hydrogen and one or more of acetylene, fullerene and anthracene in the presence of a microwave induced plasma while maintaining the substrate temperature less than about 500.degree. C. to deposit nanocrystalline diamond on the seeded substrate surface at a rate not less than about 0.2 microns/hour. Coatings of nanocrystalline diamond with average particle diameters of less than about 20 nanometers can be deposited with thermal budgets of 500.degree. C.-4 hours or less onto a variety of substrates such as MEMS devices.

  16. In vitro bioactivity and osteoblast response of porous NiTi synthesized by SHS using nanocrystalline Ni-Ti reaction agent.

    Science.gov (United States)

    Gu, Y W; Li, H; Tay, B Y; Lim, C S; Yong, M S; Khor, K A

    2006-08-01

    Porous NiTi with an average porosity of 55 vol % and a general pore size of 100-600 microm was synthesized by self-propagating high temperature synthesis (SHS) with the addition of mechanically alloyed nanocrystalline Ni-Ti as the reaction agent. The SHS of porous NiTi using elemental powders was also performed for comparison. To enhance the bioactivity of the metal surface, porous NiTi synthesized by nanocrystalline Ni-Ti was subjected to chemical treatment to form a layer of TiO(2) coating. The porous NiTi with TiO(2) coating was subsequently immersed in a simulated body fluid (SBF) to investigate its apatite forming ability. The effects of the addition of nanocrystalline Ni-Ti as reaction agent and the application of apatite coating on osteoblastic behavior were studied in primary cultures of human osteoblast cells. Results showed that the main phases in porous NiTi synthesized by elemental powders were NiTi, Ti(2)Ni, and unreacted free Ni. By using nanocrystalline Ni-Ti as reaction agent, the secondary intermetallic phase of Ti(2)Ni was significantly reduced and the free Ni was eliminated. TiO(2) coating with anatase phase was formed on the surface of porous NiTi after the chemical treatment. A layer consisting of nanocrystalline carbonate-containing apatite was formed on the surface of TiO(2) coating after soaking in SBF. The preliminary cell culture studies showed that the porous NiTi synthesized with the addition of nanocrystalline Ni-Ti attracted marked attachment and proliferation of the osteoblast cells. This gives the evidence of the potential biomedical applications of the porous NiTi.

  17. Nano-crystalline CNx Films and Field Electron Emission Properties

    Institute of Scientific and Technical Information of China (English)

    张兰; 马会中; 李会军; 杨仕娥; 姚宁; 胡欢陵; 张兵临

    2003-01-01

    CNx films with x ≈ 0.5 were prepared on to a titanium coated ceramic substrate by using microwave plasma enhanced chemical vapour deposition. As-deposited films were studied by x-ray photoelectron spectroscopy (XPS), x-ray diffraction, and scanning electron microscopy. The films consist of nano-crystalline grains with sites in a range of 20-40nm approximately. The interplanar distance (d-value) of the nano-crystalline structure determined from the peak position of x-ray diffraction was found to be 0.336nm. This value is consistent with the d-value of graphite. XPS measurements of the N1 s and C1 s core levels for the same sample demonstrate two types of bonding structures between carbon and nitrogen atoms, corresponding to sp2 C-N and sp3 C-N. It is suggested that the N atoms mainly exist in aromatic rings of the nano-graphite layers by substituting carbon positions with nitrogen. Field electron emission characteristics of the film were tested. The turn-on field of the emission was as Iow as 1.1 V/μm.

  18. Electron Backscatter Diffraction and Transmission Kikuchi Diffraction Analysis of an Austenitic Stainless Steel Subjected to Surface Mechanical Attrition Treatment and Plasma Nitriding.

    Science.gov (United States)

    Proust, Gwénaëlle; Retraint, Delphine; Chemkhi, Mahdi; Roos, Arjen; Demangel, Clemence

    2015-08-01

    Austenitic 316L stainless steel can be used for orthopedic implants due to its biocompatibility and high corrosion resistance. Its range of applications in this field could be broadened by improving its wear and friction properties. Surface properties can be modified through surface hardening treatments. The effects of such treatments on the microstructure of the alloy were investigated here. Surface Mechanical Attrition Treatment (SMAT) is a surface treatment that enhances mechanical properties of the material surface by creating a thin nanocrystalline layer. After SMAT, some specimens underwent a plasma nitriding process to further enhance their surface properties. Using electron backscatter diffraction, transmission Kikuchi diffraction, energy dispersive spectroscopy, and transmission electron microscopy, the microstructural evolution of the stainless steel after these different surface treatments was characterized. Microstructural features investigated include thickness of the nanocrystalline layer, size of the grains within the nanocrystalline layer, and depth of diffusion of nitrogen atoms within the material.

  19. Effect of plasma nitriding treatment on structural, tribological and electrochemical properties of commercially pure titanium.

    Science.gov (United States)

    Çelik, İlhan; Karakan, Mehmet

    2016-02-01

    In this study, plasma nitriding treatment was applied to commercially pure titanium (Grade 2). Structural properties, electrochemical and tribological behaviours of the nitrided pure titanium specimens were comparatively investigated. Microstructure and morphology of the plasma nitrided specimens were analysed by X-ray diffraction and scanning electron microscopy. Furthermore, corrosion tests were conducted in Ringer's solution, which represents a human body environment, to determine electrochemical properties. Then, tribological and frictional properties were investigated using pin-on-disc tribometer, and a micro-hardness tester was used to measure the hardness of the coatings. The results showed that plasma nitrided specimens exhibited higher surface hardness than the untreated specimens did. In addition, the plasma nitrided specimens at 700 °C presented significantly better performance than the other plasma nitrided specimens (at 500 °C and 600 °C) under dry wear conditions. Moreover, corrosion test results showed that corrosion behaviours of untreated and nitrided samples had similar characteristic. © IMechE 2015.

  20. Functionalized boron nitride nanotubes

    Science.gov (United States)

    Sainsbury, Toby; Ikuno, Takashi; Zettl, Alexander K

    2014-04-22

    A plasma treatment has been used to modify the surface of BNNTs. In one example, the surface of the BNNT has been modified using ammonia plasma to include amine functional groups. Amine functionalization allows BNNTs to be soluble in chloroform, which had not been possible previously. Further functionalization of amine-functionalized BNNTs with thiol-terminated organic molecules has also been demonstrated. Gold nanoparticles have been self-assembled at the surface of both amine- and thiol-functionalized boron nitride Nanotubes (BNNTs) in solution. This approach constitutes a basis for the preparation of highly functionalized BNNTs and for their utilization as nanoscale templates for assembly and integration with other nanoscale materials.

  1. Diffusion characteristics of plasma nitrided hard chromium on AISI 1010 steel

    Energy Technology Data Exchange (ETDEWEB)

    Danisman, Murat [Gedik Univ., Istanbul (Turkey). Electronic Engineering Dept.; Kocabas, Mustafa; Cansever, Nurhan [Yildiz Technical Univ., Istanbul (Turkey)

    2015-06-01

    In order to investigate the different Cr-N formation characteristics of plasma nitrided hard Cr coatings, Cr was electrodeposited on AISI 1010 steel and plasma nitrided at 600, 700 and 800 C for 3 h, 5 h and 7 h, respectively. Phase analyses of resulting Cr-N phases and grain size of Cr layer before and after nitriding process were calculated by X-ray diffraction analysis. Structure of nitride layer and its thickness were analyzed using scanning electron microscopy micrographs. The micrographs indicated that samples consisted of three distinctive layers. In order to distinguish these layers, scanning electron microscopy and energy dispersive spectroscopy (EDX) analysis were used as well as elemental distribution versus depth was plotted. The Cr-N diffusion was investigated by layer thickness measurements, and diffusion coefficient as well as activation energies were calculated.

  2. Micromechanics Modeling of Fracture in Nanocrystalline Metals

    Science.gov (United States)

    Glaessgen, E. H.; Piascik, R. S.; Raju, I. S.; Harris, C. E.

    2002-01-01

    Nanocrystalline metals have very high theoretical strength, but suffer from a lack of ductility and toughness. Therefore, it is critical to understand the mechanisms of deformation and fracture of these materials before their full potential can be achieved. Because classical fracture mechanics is based on the comparison of computed fracture parameters, such as stress intlmsity factors, to their empirically determined critical values, it does not adequately describe the fundamental physics of fracture required to predict the behavior of nanocrystalline metals. Thus, micromechanics-based techniques must be considered to quanti@ the physical processes of deformation and fracture within nanocrystalline metals. This paper discusses hndamental physicsbased modeling strategies that may be useful for the prediction Iof deformation, crack formation and crack growth within nanocrystalline metals.

  3. Bilirubin adsorption on nanocrystalline titania films

    Energy Technology Data Exchange (ETDEWEB)

    Yang Zhengpeng [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Si Shihui [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)]. E-mail: sishihui@mail.csu.edu.cn; Fung Yingsing [Department of Chemistry, University of Hong Kong, Pokfulam Road, Hong Kong (China)

    2007-02-26

    Bilirubin produced from hemoglobin metabolism and normally conjugated with albumin is a kind of lipophilic endotoxin, and can cause various diseases when its concentration is high. Bilirubin adsorption on the nanocrystalline TiO{sub 2} films was investigated using quartz crystal microbalance, UV-vis and IR techniques, and factors affecting its adsorption such as pH, bilirubin concentration, solution ionic strength, temperature and thickness of TiO{sub 2} films were discussed. The amount of adsorption and parameters for the adsorption kinetics were estimated from the frequency measurements of quartz crystal microbalance. A fresh surface of the nanocrystalline TiO{sub 2} films could be photochemically regenerated because holes and hydroxyl radicals were generated by irradiating the nanocrystalline TiO{sub 2} films with UV light, which could oxidize and decompose organic materials, and the nanocrystalline TiO{sub 2} films can be easily regenerated when it is used as adsorbent for the removal of bilirubin.

  4. Effect of High-Entropy Components of Nitride Layers on Nitrogen Content and Hardness of (TiN-Cu/(AlNbTiMoVCrN Vacuum-Arc Multilayer Coatings

    Directory of Open Access Journals (Sweden)

    V.М. Beresnev

    2016-06-01

    Full Text Available An integrated research of links in the “content-structure-properties” chain in structural engineering of (TiN-Cu/(AlNbTiMoVCrN multilayer coatings was carried out with application of elemental and X-ray diffraction analysis as well as microhardness testing. It has been found that formation of the second layer based on a high-entropy alloy even with a relatively small content of components (below 1 wt % leads to formation of a solid solution FCC lattice phase. Compared to TiN-Cu singlelayer coatings, the multilayer coating based on a (TiN-Cu/(AlNbTiMoVCrN system has an increased nitrogen content and an enhanced hardness of up to 24.5 GPa.

  5. Effects of Aqueous Vapour Consistence in Nitriding Furnace on the Quality of the Sintered Nitride

    Institute of Scientific and Technical Information of China (English)

    WANGZijiang

    1998-01-01

    If the aqueous vapour consistence is too high(>0.7%),it is very disadvantageous to the sintered products in the nitriding furnace,when silcon nitride bonded silicon carbide products are synthesized by nitridation of silicon.

  6. Gas sensing properties of nanocrystalline diamond at room temperature

    Directory of Open Access Journals (Sweden)

    Marina Davydova

    2014-12-01

    Full Text Available This study describes an integrated NH3 sensor based on a hydrogenated nanocrystalline diamond (NCD-sensitive layer coated on an interdigitated electrode structure. The gas sensing properties of the sensor structure were examined using a reducing gas (NH3 at room temperature and were found to be dependent on the electrode arrangement. A pronounced response of the sensor, which was comprised of dense electrode arrays (of 50 µm separation distance, was observed. The sensor functionality was explained by the surface transfer doping effect. Moreover, the three-dimensional model of the current density distribution of the hydrogenated NCD describes the transient flow of electrons between interdigitated electrodes and the hydrogenated NCD surface, that is, the formation of a closed current loop.

  7. Erosion–corrosion and corrosion properties of DLC coated low temperature Erosion–corrosion and corrosion properties of DLC coated low temperature

    DEFF Research Database (Denmark)

    Jellesen, Morten Stendahl; Christiansen, Thomas; Hilbert, Lisbeth Rischel

    2009-01-01

    of AISI 316 as substrate for DLC coatings are investigated. Corrosion and erosion–corrosion measurements were carried out on low temperature nitrided stainless steel AISI 316 and on low temperature nitrided stainless steel AISI 316 with a top layer of DLC. The combination of DLC and low temperature...

  8. Charge Transfer in Nanocrystalline Semiconductor Electrodes

    Directory of Open Access Journals (Sweden)

    M. Bouroushian

    2013-01-01

    Full Text Available Nanocrystalline electrodes in liquid junction devices possess a number of unique properties arising from their convoluted structure and the dimensions of their building units. The light-induced charge separation and transport in photoelectrochemical systems using nanocrystalline/nanoporous semiconductor electrodes is discussed here in connection with the basic principles of the (Schottky barrier theory. Recent models for charge transfer kinetics in normal and unipolar (dye-sensitized cells are reviewed, and novel concepts and materials are considered.

  9. Does nanocrystalline silver have a transferable effect?

    Science.gov (United States)

    Nadworny, Patricia L; Landry, Breanne K; Wang, JianFei; Tredget, Edward E; Burrell, Robert E

    2010-01-01

    This study examined the mechanism of nanocrystalline silver antiinflammatory activity, and tested nanocrystalline silver for systemic antiinflammatory effects. Secondary ion mass spectroscopy of skin treated directly with nanocrystalline silver for 24 hours showed that at skin surfaces there were significant deposits at weights corresponding to Ag, AgO, AgCl, AgNO(3), Ag(2)O, and silver clusters Ag(2-6), but silver penetration was minimal. To test for translocation of the effect, a porcine contact dermatitis model in which wounds were induced on one side of the back and then treated with nanocrystalline silver on the opposite side of the back was used. Visual and histological data showed improvement relative to animals treated with saline only. Significantly increased induction of apoptosis in the inflammatory cells present in the dermis was observed with remote nanocrystalline silver treatments. In addition, immunohistochemical analysis showed decreased levels of proinflammatory cytokines tumor necrosis factor-alpha and interleukin-8, and increased levels of antiinflammatory cytokine interleukin-4, epidermal growth factor, keratinocyte growth factor, and keratinocyte growth factor-2. Thus, the antiinflammatory effects of nanocrystalline silver appear to be induced by interactions with cells in the top layers of the skin, which then release biological signals resulting in widespread antiinflammatory activity.

  10. Plastic deformation of nanocrystalline nickel

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A high-resolution electron microscopy study has uncovered the plastic behavior of accommodating large strains in nanocrystalline (NC) Ni subject to cold rolling at liquid nitrogen temperature. The activation of grain-boundary-mediated-plasticity is evidenced in NC-Ni, including twinning and formation of stacking fault via partial dislocation slips from the grain boundary. The formation and storage of 60? full dislocations are observed inside NC-grains. The grain/twin boundaries act as the barriers of dislocation slips, leading to dislocation pile-up, severe lattice distortion, and formation of sub-grain boundary. The vicinity of grain/twin boundary is where defects preferentially accumulate and likely the favorable place for onset of plastic deformation. The present results indicate the heterogeneous and multiple natures of accommodating plastic strains in NC-grains.

  11. Plastic deformation of nanocrystalline nickel

    Institute of Scientific and Technical Information of China (English)

    WU XiaoLei

    2009-01-01

    A high-resolution electron microscopy study has uncovered the plastic behavior of accommodating large strains in nanocrystalline(NC)Ni subject to cold rolling at liquid nitrogen temperature.The acti vation of grain-boundary-mediated-plasticity is evidenced in NC-Ni,including twinning and formation of stacking fault via partial dislocation slips from the grain boundary.The formation and storage of 60° full dislocations are observed inside NC-grains.The grain/twin boundaries act as the barriers of dislocation slips,leading to dislocation pile-up,severe lattice distortion,and formation of sub-grain boundary.The vicinity of grain/twin boundary is where defects preferentially accumulate and likely the favorable place for onset of plastic deformation.The present results indicate the heterogeneous and multiple natures of accommodating plastic strains in NC-grains.

  12. High vacuum tribology of polycrystalline diamond coatings

    Indian Academy of Sciences (India)

    Awadesh K Mallik; S A Shivashankar; S K Biswas

    2009-10-01

    Polycrystalline diamond coatings have been grown on unpolished side of Si(100) wafers by hot filament chemical vapour deposition process. The morphology of the grown coatings has been varied from cauliflower morphology to faceted morphology by manipulation of the growth temperature from 700°C to 900°C and methane gas concentration from 3% to 1·5%. It is found that the coefficient of friction of the coatings under high vacuum of 133·32 × 10-7 Pa (10-7 torr) with nanocrystalline grains can be manipulated to 0·35 to enhance tribological behaviour of bare Si substrates.

  13. Nanocrystalline cellulose from coir fiber: preparation, properties, and applications

    Science.gov (United States)

    Nanocrystalline cellulose derived from various botanical sources offers unique and potentially useful characteristics. In principle, any cellulosic material can be considered as a potential source of a nanocrystalline material, including crops, crop residues, and agroindustrial wastes. Because of t...

  14. Tissue response to implanted ceramic-coated titanium alloys in rats.

    Science.gov (United States)

    Satomi, K; Akagawa, Y; Nikai, H; Tsuru, H

    1988-07-01

    In order to assess the tissue compatibility of the hybrid materials for the dental implant (hydroxyapatite, titanium oxide and titanium nitride coated titanium alloys), tissue response to these materials implanted in the rat subcutaneous tissue was histologically examined. Initial inflammatory response was less evident in titanium oxide coated and non-coated titanium alloys. All materials were encapsulated by thin fibrous connective tissues. The membrane thickness of hydroxyapatite coated titanium alloy was significantly higher than that of titanium nitride coated one. These results suggest that all materials possess favourable tissue compatibility and may encourage clinical use as the dental implant.

  15. Determination of the Influence of c-BN+h-BN Coating Structure on Brittleness

    Institute of Scientific and Technical Information of China (English)

    Maciej Kupczyk; Adam Lejwoda; Przemyslaw Cieszkowski; Przemyslaw Libuda

    2004-01-01

    In the article is presented the brittleness study of boron nitride coatings deposited on cutting edges made of cemented carbides by the pulse-plasma method (PPD). Influences of the structure (density, pores, microcracks) of coating material on the brittleness and on selected technological parameters of boron nitride formation by PPD method particularly taking into account discharge voltage on brittleness are shown. Differences between values of both a1(300) and a1(500)coefficients characterized susceptibility to coatings cracking of investigated coating manufactured using different values of discharge voltage were defined. Results of an investigations have been confirmed usefulness of Palmqvist's method for measurement of coating susceptibility to brittle cracking.

  16. Determination of the Influence of c-BN+h-BN Coating Structure on Brittleness

    Institute of Scientific and Technical Information of China (English)

    MaciejKupczyk; AdamLejwoda; PrzemyslawCieszkowski; PrzemyslawLibuda

    2004-01-01

    In the article is presented the brittleness study of boron nitride coatings deposited on cutting edges made of cemented carbides by the pulse-plasma method (PPD). Influences of the structure (density, pores, microcracks) of coating material on the brittleness and on selected technological parameters of boron nitride formation by PPD method particularly taking into account discharge voltage on brittleness are shown. Differences between values of both a1(300) and a1(500)coefficients characterized susceptibility to coatings cracking of investigated coating manufactured using different values of discharge voltage were defined. Results of an investigations have been confirmed usefulness of Palmqyist's method for measurement of coating susceptibility to brittle cracking.

  17. Study of the Active Screen Plasma Nitriding

    Institute of Scientific and Technical Information of China (English)

    Zhao Cheng; C. X. Li; H. Dong; T. Bell

    2004-01-01

    Active screen plasma nitriding (ASPN) is a novel nitriding process, which overcomes many of the practical problems associated with the conventional DC plasma nitriding (DCPN). Experimental results showed that the metallurgical characteristics and hardening effect of 722M24 steel nitrided by ASPN at both floating potential and anodic (zero) potential were similar to those nitrided by DCPN. XRD and high-resolution SEM analysis indicated that iron nitride particles with sizes in sub-micron scale were deposited on the specimen surface in AS plasma nitriding. These indicate that the neutral iron nitride particles, which are sputtered from the active screen and transferred through plasma to specimen surface, are considered to be the dominant nitrogen carder in ASPN. The OES results show that NH could not be a critical species in plasma nitriding.

  18. Modification of silicon nitride and silicon carbide surfaces for food and biosensor applications

    NARCIS (Netherlands)

    Rosso, M.

    2009-01-01

    Silicon-rich silicon nitride (SixN4, x > 3) is a robust insulating material widely used for the coating of microdevices: its high chemical and mechanical inertness make it a material of choice for the reinforcement of fragile microstructures (e.g. suspended microcantilevers, micro-fabricated memb

  19. Modification of silicon nitride and silicon carbide surfaces for food and biosensor applications

    NARCIS (Netherlands)

    Rosso, M.

    2009-01-01

    Silicon-rich silicon nitride (SixN4, x > 3) is a robust insulating material widely used for the coating of microdevices: its high chemical and mechanical inertness make it a material of choice for the reinforcement of fragile microstructures (e.g. suspended microcantilevers, micro-fabricated

  20. Fabrication of Duplex Coated U-Mo-Ti Atomized Powder

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Ji Min; Kim, Woo Jeong; Lee, Kyu Hong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Ryu, Ho Jin [Korea Advanced Institue of Science and Technology, Daejeon (Korea, Republic of)

    2013-10-15

    The results of an annealing test showed that the coating layers inhibit the formation of interaction layers. The results of duplex coating showed that nitride coating layers inhibit the formation of other coating layers. High-density U-Mo alloys are regarded as promising candidates for advanced research reactor fuel as they have shown stable irradiation performance when compared to other uranium alloys and compounds. However, interaction layer formation between the U-Mo alloys and Al matrix degrades the irradiation performance of U-Mo dispersion fuel. Therefore, the addition of Ti in U-Mo alloys, the addition of Si in a Al matrix, and silicide or nitride coating on the surface of U-Mo particles have been proposed to inhibit the interaction layer growth. In this study, U-Mo-Ti alloy powder was produced using a centrifugal atomization method. In addition, nitride and silicide duplex coating layers were fabricated on the surface of the U-Mo-Ti particles. The coated powders were characterized by using X-ray diffraction, SEM, and EDX. Silicide and nitride single coating layers were fabricated on the surface of U-7wt%Mo-1wt%Ti alloys with a thickness of about 10.20 micrometers.

  1. Human periodontal ligament fibroblasts stimulated by nanocrystalline hydroxyapatite paste or enamel matrix derivative. An in vitro assessment of PDL attachment, migration, and proliferation

    NARCIS (Netherlands)

    Kasaj, A.; Willershausen, B.; Junker, R.; Stratul, S.I.; Schmidt, M.

    2012-01-01

    We determined the effects of soluble or coated nanocrystalline hydroxyapatite paste (nano-HA) and enamel matrix derivative (EMD) on proliferation, adhesion, and migration of periodontal ligament fibroblasts (PDLs). Cultured PDLs were stimulated with nano-HA paste or EMD in a soluble form or were

  2. 10% Efficiency Dye-sensitized Solar Cells Using P25 TiO2 Nanocrystalline Electrode Prepared by a Bead-milling Method

    National Research Council Canada - National Science Library

    Yamamoto, Yasuhiro; Kawaraya, Masahide; Segawa, Hiroshi; Uchida, Satoshi; Kano, Junya; Saito, Fumio; Tsujimoto, Kazuki; Saito, Tsubasa; Ito, Seigo

    2011-01-01

    ...). The coated nanocrystalline TiO2 electrodes were evaluated using X-ray diffraction (XRD) and a haze meter. The shape and crystallinity of the TiO2 nanoparticles were not changed, but the transparency was improved by the bead-milling process...

  3. Synthesis of ternary metal nitride nanoparticles using mesoporous carbon nitride as reactive template.

    Science.gov (United States)

    Fischer, Anna; Müller, Jens Oliver; Antonietti, Markus; Thomas, Arne

    2008-12-23

    Mesoporous graphitic carbon nitride was used as both a nanoreactor and a reactant for the synthesis of ternary metal nitride nanoparticles. By infiltration of a mixture of two metal precursors into mesoporous carbon nitride, the pores act first as a nanoconfinement, generating amorphous mixed oxide nanoparticles. During heating and decomposition, the carbon nitride second acts as reactant or, more precisely, as a nitrogen source, which converts the preformed mixed oxide nanoparticles into the corresponding nitride (reactive templating). Using this approach, ternary metal nitride particles with diameters smaller 10 nm composed of aluminum gallium nitride (Al-Ga-N) and titanium vanadium nitride (Ti-V-N) were synthesized. Due to the confinement effect of the carbon nitride matrix, the composition of the resulting metal nitride can be easily adjusted by changing the concentration of the preceding precursor solution. Thus, ternary metal nitride nanoparticles with continuously adjustable metal composition can be produced.

  4. Microtribology of Nitrogen-doped Amorphous Carbon Coatings

    Institute of Scientific and Technical Information of China (English)

    Dong F. Wang

    2004-01-01

    The friction, wear and lubrication of carbon nitride coatings on silicon substrates are studied using a spherical diamond counter-face with nano-scale asperities. The first part of this paper clarifies the coating thickness effect on frictional behavior of carbon nitride coatings. The second part of this paper reports empirical data on wear properties in repeated sliding contacts through in situ examination and post-sliding observation. The third part will concentrate on wear mechanisms for the transition from "No observable wear particles" to "Wear particle generation." In light of the above tribological study, the application of carbon nitride coatings to MicroElectroMechanical system (MEMS) is therefore discussed from view points of both microtribology and micromachining.

  5. Evaluation of the Effect of Different Plasma-Nitriding Parameters on the Properties of Low-Alloy Steel

    Science.gov (United States)

    Zdravecká, Eva; Slota, Ján; Solfronk, Pavel; Kolnerová, Michaela

    2017-07-01

    This work is concerned with the surface treatment (ion nitriding) of different plasma-nitriding parameters on the characteristics of DIN 1.8519 low-alloy steel. The samples were nitrided from 500 to 570 °C for 5-40 h using a constant 25% N2-75% H2 gaseous mixture. Lower temperature (500-520 °C) favors the formation of compound layers of γ' and ɛ iron nitrides in the surface layers, whereas a monophase γ'-Fe4 N layer can be obtained at a higher temperature. The hardness of this layer can be obtained when nitriding is performed at a higher temperature, and the hardness decreases when the temperature increases to 570 °C. These results indicate that pulsed plasma nitriding is highly efficient at 550 °C and can form thick and hard nitrided layers with satisfactory mechanical properties. The results show the optimized nitriding process at 540 °C for 20 h. This process can be an interesting means of enhancing the surface hardness of tool steels to forge dies compared to stamped steels with zinc coating with a reduced coefficient of friction and improving the anti-sticking properties of the tool surface.

  6. In-situ preparation of polymer-coated alumina nanopowders by chemical vapor synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Schallehn, M.; Winterer, M.; Weirich, T.E.; Hahn, H. [Inst. of Materials Science, Darmstadt Univ. of Technology, Darmstadt (Germany); Keiderling, U. [Hahn-Meitner-Inst., Berlin (Germany)

    2003-01-01

    Nanocrystalline alumina particles coated with polyethylene have been prepared by a two-step chemical vapor synthesis (CVS) process using a hot-wall reactor to synthesize the nanocrystalline alumina core, and a RF plasma reactor for the subsequent polymer coating. The particle radius is about 4 nm, with the radius of the ceramic core being about 2.5 nm and the coating thickness about 1.5 nm. The powders have been characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), small-angle neutron scattering (SANS), and high-resolution transmission electron microscopy (HRTEM). (orig.)

  7. Parametric study of an HVOF process for the deposition of nanostructured WC-Co coatings

    Science.gov (United States)

    Bartuli, Cecilia; Valente, Teodoro; Cipri, Fabio; Bemporad, Edoardo; Tului, Mario

    2005-06-01

    Nanocrystalline WC-Co coatings were deposited by high velocity oxyfuel from commercial nanostructured composite powders. Processing parameters were optimized for maximal retention of the nanocrystalline size and for minimal decarburation of the ceramic reinforcement. Thermochemical and gas-dynamical properties of gas and particle flows within the combustion flame were identified in various operating conditions by computational fluid-dynamics (CFD) simulation. Significant improvements of the mechanical properties of the coatings were obtained: a decrease of the friction coefficient was measured for the nanostructured coatings, together with an increase of microhardness and fracture toughness.

  8. Boron nitride converted carbon fiber

    Science.gov (United States)

    Rousseas, Michael; Mickelson, William; Zettl, Alexander K.

    2016-04-05

    This disclosure provides systems, methods, and apparatus related to boron nitride converted carbon fiber. In one aspect, a method may include the operations of providing boron oxide and carbon fiber, heating the boron oxide to melt the boron oxide and heating the carbon fiber, mixing a nitrogen-containing gas with boron oxide vapor from molten boron oxide, and converting at least a portion of the carbon fiber to boron nitride.

  9. Optical stability of silicon nitride MIS inversion layer solar cells

    Science.gov (United States)

    Jaeger, K.; Hezel, R.

    1985-09-01

    For MIS inversion layer solar cells with silicon nitride as an AR coating, accelerated optical stress tests were performed. Degradation of the cell characteristics occurred which was found to be caused by photons with energies equal to or greater than 3.7 eV (wavelength of 335 nm or less). Generation of interface states at the silicon-insulator interface by UV light is shown to be the mechanism responsible. The original cell data could be completely restored by heat treatment (activation energy 0.5 eV) and partially by illumination with short-wavelength light. As the most striking result, however, it is demonstrated that the UV light-induced instability can be drastically improved by incorporation of cesium ions into the silicon nitride layer. An interpretation is given for this effect.

  10. Boron-Doped Nanocrystalline Diamond Electrodes for Neural Interfaces: In vivo Biocompatibility Evaluation.

    Science.gov (United States)

    Alcaide, María; Taylor, Andrew; Fjorback, Morten; Zachar, Vladimir; Pennisi, Cristian P

    2016-01-01

    Boron-doped nanocrystalline diamond (BDD) electrodes have recently attracted attention as materials for neural electrodes due to their superior physical and electrochemical properties, however their biocompatibility remains largely unexplored. In this work, we aim to investigate the in vivo biocompatibility of BDD electrodes in relation to conventional titanium nitride (TiN) electrodes using a rat subcutaneous implantation model. High quality BDD films were synthesized on electrodes intended for use as an implantable neurostimulation device. After implantation for 2 and 4 weeks, tissue sections adjacent to the electrodes were obtained for histological analysis. Both types of implants were contained in a thin fibrous encapsulation layer, the thickness of which decreased with time. Although the level of neovascularization around the implants was similar, BDD electrodes elicited significantly thinner fibrous capsules and a milder inflammatory reaction at both time points. These results suggest that BDD films may constitute an appropriate material to support stable performance of implantable neural electrodes over time.

  11. Boron-doped nanocrystalline diamond electrodes for neural interfaces: In vivo biocompatibility evaluation

    Directory of Open Access Journals (Sweden)

    María eAlcaide

    2016-03-01

    Full Text Available Boron-doped nanocrystalline diamond (BDD electrodes have recently attracted attention as materials for neural electrodes due to their superior physical and electrochemical properties, however their biocompatibility remains largely unexplored. In this work, we aim to investigate the in vivo biocompatibility of BDD electrodes in relation to conventional titanium nitride (TiN electrodes using a rat subcutaneous implantation model. High quality BDD films were synthesized on electrodes intended for use as an implantable neurostimulation device. After implantation for 2 and 4 weeks, tissue sections adjacent to the electrodes were obtained for histological analysis. Both types of implants were contained in a thin fibrous encapsulation layer, the thickness of which decreased with time. Although the level of neovascularization around the implants was similar, BDD electrodes elicited significantly thinner fibrous capsules and a milder inflammatory reaction at both time points. These results suggest that BDD films may constitute an appropriate material to support stable performance of implantable neural electrodes over time.

  12. Nanostructured TiC/a-C coatings for low friction and wear resistant applications

    NARCIS (Netherlands)

    Pei, Y.T.; Galvan, D.; Hosson, J.Th.M. De; Cavaleiro, A.

    2005-01-01

    Closed-field unbalanced and balanced magnetron sputtering was used to deposit nanocrystalline TiC (nc-TiC)/amorphous carbon (a-C) nanocomposite coatings with hydrogenated or hydrogen-free a-C matrix, respectively. The contents of Ti and C in the coatings have been varied over the full range of inter

  13. Nanostructured TiC/a-C coatings for low friction and wear resistant applications

    NARCIS (Netherlands)

    Pei, Y.T.; Galvan, D.; Hosson, J.Th.M. De; Cavaleiro, A.

    2005-01-01

    Closed-field unbalanced and balanced magnetron sputtering was used to deposit nanocrystalline TiC (nc-TiC)/amorphous carbon (a-C) nanocomposite coatings with hydrogenated or hydrogen-free a-C matrix, respectively. The contents of Ti and C in the coatings have been varied over the full range of

  14. D. C. Plasma-Sprayed Coatings of Nanostructured Alumina-Titania-Silica

    Institute of Scientific and Technical Information of China (English)

    蒋显亮; 刘敏

    2002-01-01

    Nanocrystalline powders of w(Al2O3) = 95%, w(TiO2) = 3%, and w(SiO2) = 2%,were reprocessed into agglomerated particles for plasma spraying, by using consecutive steps ofball milling, slurry forming, spray drying, and heat treatment. D. C. plasma was used to spraythe agglomerated nanocrystalline powders, and resultant coatings were deposited on the substrate of stainless steel. Scanning electron microscopy (SEM) was used to examine the morphology of the agglomerated powders and the cross section of the alumina-titania-silica coatings. Exper-imental results show that the agglomerated nanocrystalline particles are spherical, with a size from (10~90)μm. The flow ability of the nanocrystalline powders is greatly improved after the reprocessing. The coatings deposited by the plasma spraying are mainly of nanostructure. Un-like conventional plasma-sprayed coatings, no laminar layer could be found in the nanostructured coatings. Although the nanostructured coatings have a lower microhardness than conventional microstructured coatings, the toughness of the nanostructured ceramic coatings is significantly improved.

  15. On the composition analysis of nc-TiC/a-C : H nanocomposite coatings

    NARCIS (Netherlands)

    Chechenin, N.G.; Chernykh, P.N.; Kulikauskas, V.S.; Pei, Y.T.; Vainshtein, D.; Hosson, J.Th.M. De

    2008-01-01

    Using a set of ion beam analysis (IBA) techniques the compositions of hydrogenated diamond-like carbon (DLC) nanocomposite coatings are scrutinized, including the hydrogen content. The coatings are composed of two constituents: amorphous hydrocarbon matrix (a-C : H) and nanocrystalline titanium carb

  16. On the development of a dual-layered diamond-coated tool for the effective machining of titanium Ti-6Al-4V alloy

    Science.gov (United States)

    Srinivasan, Balaji; Ramachandra Rao, M. S.; Rao, Balkrishna C.

    2017-01-01

    This work is focused on the development of a dual-layered diamond-coated tungsten carbide tool for machining titanium Ti-6Al-4V alloy. A hot-filament chemical vapor deposition technique was used to synthesize diamond films on tungsten carbide tools. A boron-doped diamond interlayer was added to a microcrystalline diamond layer in an attempt to improve the interface adhesion strength. The dual-layered diamond-coated tool was employed in machining at cutting speeds in the range of 70 to 150 m min-1 with a lower feed and a lower depth of cut of 0.5 mm rev-1 and 0.5 mm, respectively, to operate in the transition from adhesion- to diffusion-tool-wear and thereby arrive at suitable conditions for enhancing tool life. The proposed tool was then compared, on the basis of performance under real-time cutting conditions, with commercially available microcrystalline diamond, nanocrystalline diamond, titanium nitride and uncoated tungsten carbide tools. The life and surface finish of the proposed dual-layered tool and uncoated tungsten carbide were also investigated in interrupted cutting such as milling. The results of this study show a significant improvement in tool life and finish of Ti-6Al-4V parts machined with the dual-layered diamond-coated tool when compared with its uncoated counterpart. These results pave the way for the use of a low-cost tool, with respect to, polycrystalline diamond for enhancing both tool life and machining productivity in critical sectors fabricating parts out of titanium Ti-6Al-4V alloy. The application of this coating technology can also be extended to the machining of non-ferrous alloys owing to its better adhesion strength.

  17. Increased upper critical field for nanocrystalline MoN thin films deposited on AlN buffered substrates at ambient temperature

    Science.gov (United States)

    Baskaran, R.; Thanikai Arasu, A. V.; Amaladass, E. P.; Vaidhyanathan, L. S.; Baisnab, D. K.

    2016-05-01

    Molybdenum nitride (MoN) thin films have been deposited using reactive DC magnetron sputtering on aluminum nitride buffered oxidized silicon substrates at ambient temperature. GIXRD of aluminum nitride (AlN) deposited under similar conditions has revealed the formation of wurtzite phase AlN. GIXRD characterization of molybdenum thin films deposited on AlN buffered oxidized silicon substrates has indicated the formation of nanocrystalline MoN thin films. The electrical resistivity measurements indicate MoN thin films have a superconducting transition temperature of ~8 K. The minimum transition width of the MoN thin film is 0.05 K at 0 T. The inferred upper critical field B c2(0) for these nanocrystalline MoN thin films obtained by fitting the temperature dependence of critical field with Werthamer, Helfand and Hohenberg theory lies in the range of 17-18 T which is the highest reported in literature for MoN thin films.

  18. New method for synthesis of metal carbides, nitrides and carbonitrides

    Energy Technology Data Exchange (ETDEWEB)

    Koc, R.; Folmer, J.S.; Kodambaka, S.K. [Southern Illinois Univ., Carbondale, IL (United States)] [and others

    1997-04-01

    The purpose of this work is to develop a novel synthesis method using a carbothermic reduction reaction of carbon coated precursors for producing high purity, submicron, non-agglomerated powders of metal carbide, metal nitride and metal boride systems. The authors also want to demonstrate the advantages of the process and provide information on the applicability of the process for synthesizing related advanced ceramic powders (e.g. SiC, WC, TiN, TiB{sub 2}, Si{sub 3}N{sub 4}). During the FY96 of the project, steps are taken to investigate the reaction mechanisms and phase evolution during the formation of TiC from carbon coated titania precursors and to produce submicron TiC powders with desired stoichiometries. Depending on the carbon content in the coated titania precursor, TiC powder was produced with different stoichiometries (different amount of oxygen and free carbon).

  19. Influence of the Discharge Voltage during Pulse-Plasma Process on the Durability of Edges coated with Superhard Coatings

    Institute of Scientific and Technical Information of China (English)

    MaciejKupczyk

    2004-01-01

    In the paper the experimental results concerning the functional quality of thin, superhard coatings produced on cutting edges is described. Boron nitride coatings were deposited on insert cutting edges made cemented carbides by the pulse-plasma method. The comparative investigations of mentioned coatings have been concerned of tool life of edges during steel machining. In these investigations for the purpose of additional increase of coated edge durability an interfacial layers were applied. Presented investigations particularly pointed out to essential influence of the values of discharge voltage on the coating structure and durability of edges coated with boron nitfide.

  20. Elastic moduli and strength of nanocrystalline cubic BC2N from x-ray diffraction under nonhydrostatic compression

    Science.gov (United States)

    Dong, Haini; He, Duanwei; Duffy, Thomas S.; Zhao, Yusheng

    2009-01-01

    The stress behavior of nanocrystalline cubic boron carbon nitride (c-BC2N) was investigated using radial and axial x-ray diffractions in the diamond-anvil cell under nonhydrostatic compression up to ~100 GPa. The radial x-ray diffraction (RXRD) data yield a bulk modulus K0=276±20GPa with a fixed pressure derivative K0'=3.4 at ψ=54.7° , which corresponds to the hydrostatic compression curve. The bulk modulus obtained from axial x-ray diffraction (AXRD) gives a value of 420±11GPa . A comparative study of the observed compression curves from radial and axial diffractions shows that the ruby-fluorescence pressure scale may reflect the maximum stress under nonhydrostatic compression. It was found that nanocrystalline c-BC2N sample could support a maximum differential stress of ~38 GPa when it started to yield at ~66 GPa under uniaxial compression. Moreover, the aggregate elastic moduli of the nanocrystalline c-BC2N have been determined from the RXRD data at high pressures.

  1. Mechanochemical method for producing iron-based nitrogen-containing nanocrystalline alloys

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Iron-based products account the main volume of powder metallurgy production. Nevertheless its strength and reliability are not enough in comparison with classical cast materials. So that is why making nanostructural powder materials allows to increase strength and extend the range of products. A principally new way of nanostructure production is possible by means of iron mechanical alloying with nitride-forming and nitrogen both at the same time.Unlike classical technology of internal nitrogenation, nitrogen saturation, in our case, occurs by whole volume at plastic deformation conditions. A review of experimental results of phase forming alloys in the Fe-Ni, Fe-Ni-Cr, Fe-Ni-N, Fe-Ni-Cr-N, Fe-Cr-Ni systems prepared by mechanical alloying are given. The influence of the technological parameters of mechanical alloying, atmosphere of mechanical activation on nitrogen content and phase composition of examined alloys has been studied. Experimental results of the influence of mechanical alloying technological parameters on degree of ammonia dissociation and nitrogen content in examined alloys are presented. Heat treatment influence of mechanically alloyed, nitrogen-containing alloys on theirphase composition and structure are investigated.It was shown that using mechanical alloying, it's possible to prepare high-alloyed iron-based alloys containing more than 1% of nitrogen. It was established that technology of mechanical alloying in ammonia atmosphere allows to prepare austenitic steels with nanocrystalline structure, which affords high value of yield stress. Physico-chemical patterns of interaction between the nitrogen-containing atmosphere and nitride-forming elements under their mutual mechanical activation conditions were established in consequence of theoretical and experimental researches. Some scientific principles of nanocrystalline materials were gained by quantitative description of correlation between the mechanical dose, nitrogen potertial, nitrogen content

  2. Structural elucidation of nanocrystalline biomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Maltsev, S.

    2008-10-23

    Bone diseases, such as osteoporosis and osteoarthritis, are the second most prevalent health problem worldwide. In Germany approximately 5 millions people are affected by arthritis. Investigating biomineralization processes and bone molecular structure is of key importance for developing new drugs for preventing and healing bone diseases. Nuclear magnetic resonance (NMR) was the primary technique used due to its advantages in characterising poorly ordered and disordered materials. Compared to all the diffraction techniques that widely applied in structural investigations, the usefulness of NMR is independent of long range molecular order. This makes NMR an outstanding technique for studies of complex/amorphous materials. Conventional NMR experiments (single pulse, spin-echo, cross polarization (CP), etc.) as well as their modifications and high-end techniques (2D HETCOR, REDOR, etc.) were used in this work. Combining the contributions from different techniques enhances the information content of the investigations and can increase the precision of the overall conclusions. Also XRD, TEM and FTIR were applied to different extent in order to get a general idea of nanocrystalline hydroxyapatite crystallite structure. Results: - A new approach named 'Solid-state NMR spectroscopy using the lost I spin magnetization in polarization transfer experiments' has been developed for measuring the transferred I spin magnetization from abundant nuclei, which is normally lost when detecting the S spin magnetization. - A detailed investigation of nanocrystalline hydroxyapatite core was made to prove that proton environment of the phosphates units and phosphorus environment of hydroxyl units are the same as in highly crystalline hydroxyapatite sample. - Using XRD it was found that the surface of the hydroxyapatite nanocrystals is not completely disordered, as it was suggested before, but resembles the hydroxyapatite structure with HPO{sub 4}{sup 2-} (and some CO{sub 3}{sup

  3. The effect of pretreatment by titanium ion beam on the internal stresses and microstructure of the TiAlN coating obtained by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Perevalova, Olga, E-mail: perevalova52@mail.ru; Kalashnikov, Mark, E-mail: kmp1980@mail.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Panin, Aleksej, E-mail: pav@ispms.tsc.ru; Sergeev, Viktor, E-mail: vserg@mal.tomsknet.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    The increase in duration of titanum ion pretreatment of the substrate-austenitic steel leads to a decrease in the transverse dimensions of the nanocrystalline columnar coating Ti{sub 1−x}AlxN structure, emergence of ferritic layer between coating and substrate and an increase in the compressive macrostresses both in the coating and in the substrate.

  4. Electroformed Nanocrystalline Coatings: An Advanced Alternative to Hard Chrome Electroplating

    Science.gov (United States)

    2003-11-21

    abrasive wheels composed of rubber with embedded aluminium oxide abrasive particles (particle size: 50~200µm) were used. Table 1 shows the test conditions...electrodeposition the specimens were grit blasted with either 80-grit (batch 1) or 120-grit (batch 2) aluminium oxide at 60-psi at 90- degree angle of

  5. Structural materialization of stainless steel molds and dies by the low temperature high density plasma nitriding

    Directory of Open Access Journals (Sweden)

    Aizawa Tatsuhiko

    2015-01-01

    Full Text Available Various kinds of stainless steels have been widely utilized as a mold substrate material for injection molding and as a die for mold-stamping and direct stamping processes. Since they suffered from high temperature transients and thermal cycles in practice, they must be surface-treated by dry and wet coatings, or, by plasma nitriding. Martensitic stainless steel mold was first wet plated by the nickel phosphate (NiP, which was unstable at the high temperature stamping condition; and, was easy to crystalize or to fracture by itself. This issue of nuisance significantly lowered the productivity in fabrication of optical elements at present. In the present paper, the stainless steel mold was surface-treated by the low-temperature plasma nitriding. The nitrided layer by this surface modification had higher nitrogen solute content than 4 mass%; the maximum solid-solubility of nitrogen is usually 0.1 mass% in the equilibrium phase diagram. Owing to this solid-solution with high nitrogen concentration, the nitrided layer had high hardness of 1400 Hv within its thickness of 40 μm without any formation of nitrides after 14.4 ks plasma nitriding at 693 K. This nitrogen solid-solution treated stainless steel had thermal resistivity even at the mold-stamping conditions up to 900 K.

  6. Nanostructured thin films and coatings mechanical properties

    CERN Document Server

    2010-01-01

    The first volume in "The Handbook of Nanostructured Thin Films and Coatings" set, this book concentrates on the mechanical properties, such as hardness, toughness, and adhesion, of thin films and coatings. It discusses processing, properties, and performance and provides a detailed analysis of theories and size effects. The book presents the fundamentals of hard and superhard nanocomposites and heterostructures, assesses fracture toughness and interfacial adhesion strength of thin films and hard nanocomposite coatings, and covers the processing and mechanical properties of hybrid sol-gel-derived nanocomposite coatings. It also uses nanomechanics to optimize coatings for cutting tools and explores various other coatings, such as diamond, metal-containing amorphous carbon nanostructured, and transition metal nitride-based nanolayered multilayer coatings.

  7. 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...

  8. Plasmonic titanium nitride nanostructures for perfect absorbers

    DEFF Research Database (Denmark)

    Guler, Urcan; Li, Wen-Wei; Kinsey, Nathaniel

    2013-01-01

    We propose a metamaterial based perfect absorber in the visible region, and investigate the performance of titanium nitride as an alternative plasmonic material. Numerical and experimental results reveal that titanium nitride performs better than gold as a plasmonic absorbing material...

  9. Surface Features of Nanocrystalline Alloys

    Directory of Open Access Journals (Sweden)

    Marcel Miglierini

    2015-12-01

    Full Text Available Nanocrystalline alloys are prepared by controlled annealing of metallic glass precursors. The latter are obtained by rapid quenching of a melt on a rotating wheel. This process leads to structural deviation of the produced ribbons’ surfaces. Structural features of as-quenched and thermally annealed 57Fe81Mo8Cu1B10 ribbons were studied employing Conversion Electron Mössbauer Spectrometry (CEMS and Conversion X-ray Mössbauer Spectrometry (CXMS. Enrichment of the alloy’s composition in 57Fe helped in identification of surface crystallites that were formed even during the production process. Magnetite and bcc-Fe were found at the wheel side of the as-quenched ribbons whereas only bcc-Fe nanocrystals were uncovered at the opposite air side. Accelerated formation of bcc-Fe was observed in this side of the ribbons after annealing. The relative content of magnetite at the wheel side was almost stable in near surface areas (CEMS and in more deep subsurface regions (CXMS. It vanished completely after annealing at 550 °C. No magnetite was observed at the air side of the ribbons regardless the annealing temperature and/or depth of the scanned regions.

  10. Consolidation of nanocrystalline hydroxyapatite powder

    Directory of Open Access Journals (Sweden)

    S. Ramesh et al

    2007-01-01

    Full Text Available The effect of sintering temperature on the sinterability of synthesized nanocrystalline hydroxyapatite (HA was investigated. The starting powder was synthesized via a novel wet chemical route. HA green compacts were prepared and sintered in atmospheric condition at various temperatures ranging from 900–1300 °C. The results revealed that the thermal stability of HA phase was not disrupted throughout the sintering regime employed. In general, the results showed that above 98% of theoretical density coupled with hardness of 7.21 GPa, fracture toughness of 1.17 MPa m1/2 and Young's modulus of above 110 GPa were obtained for HA sintered at temperature as low as 1050 °C. Although the Young's modulus increased with increasing bulk density, the hardness and fracture toughness of the sintered material started to decline when the temperature was increased beyond 1000–1050 °C despite exhibiting high densities >98% of theoretical value. The occurrence of this phenomenon is believed to be associated with a thermal-activated grain growth process.

  11. Combustion synthesis of bulk nanocrystalline iron alloys

    Directory of Open Access Journals (Sweden)

    Licai Fu

    2016-02-01

    Full Text Available The controlled synthesis of large-scale nanocrystalline metals and alloys with predefined architecture is in general a big challenge, and making full use of these materials in applications still requires greatly effort. The combustion synthesis technique has been successfully extended to prepare large-scale nanocrystalline metals and alloys, especially iron alloy, such as FeC, FeNi, FeCu, FeSi, FeB, FeAl, FeSiAl, FeSiB, and the microstructure can be designed. In this issue, recent progress on the synthesis of nanocrystalline metals and alloys prepared by combustion synthesis technique are reviewed. Then, the mechanical and tribological properties of these materials with microstructure control are discussed.

  12. Combustion synthesis of bulk nanocrystalline iron alloys

    Institute of Scientific and Technical Information of China (English)

    Licai Fu; Jun Yang; Weimin Liu

    2016-01-01

    The controlled synthesis of large-scale nanocrystalline metals and alloys with predefined architecture is in general a big challenge, and making full use of these materials in applications still requires greatly effort. The combustion synthesis technique has been successfully extended to prepare large-scale nanocrystalline metals and alloys, especially iron alloy, such as FeC, FeNi, FeCu, FeSi, FeB, FeAl, FeSiAl, FeSiB, and the microstructure can be designed. In this issue, recent progress on the synthesis of nanocrystalline metals and alloys prepared by combustion synthesis technique are reviewed. Then, the mechanical and tribological properties of these materials with microstructure control are discussed.

  13. Innovative Superhard Materials and Sustainable Coatings for Advanced Manufacturing

    Science.gov (United States)

    Lee, Jay; Novikov, Nikolay

    The book contains the results of the latest achievements of leading researchers from 9 countries in the field of diamond and diamond-like carbon, cubic boron nitride and other superhard materials; high-density engineering ceramics; high pressure-high temperature technique; computer-aided modeling; diamond, cubic boron nitride, ceramic and cemented carbide tools; development, production and applications of nanostructured materials; films and wear-resistant coating; methods for quality control of tool materials and tools.

  14. GaN nanorods coated with pure BN

    Science.gov (United States)

    Han, Wei-Qiang; Zettl, A.

    2002-12-01

    We report a method to efficiently synthesize gallium nitride (GaN) nanorods coated with insulating boron nitride (BN) layers. The GaN core is crystalline (with either a cubic zincblende or hexagonal wurtzite structure) and has diameters ranging from 10 to 85 nm and lengths up to 60 μm. The outer encapsulating BN shells with typical thicknesses less than 5 nm extend fully over, and adhere well to, the entire nanorod surface.

  15. Electrochemical Characterisation of Nanocrystalline Nickel

    Directory of Open Access Journals (Sweden)

    Deepika Sachdeva

    2008-07-01

    Full Text Available Nanocry stalline nickel (nc-Ni coatings were produced by pulse electro deposition using Watts bath with sodium citrate and saccharin added as grain refining agents. The electrochemical nature of nc-Ni coatings, evaluated in 1M H2SO4 solution by electrochemical impedance spectroscopy. The corrosion rate of bulk nickel was lower than that of nc-Ni after stabilisation of free corrosion potential.Defence Science Journal, 2008, 58(4, pp.525-530, DOI:http://dx.doi.org/10.14429/dsj.58.1673

  16. Cathodic Cage Plasma Nitriding: An Innovative Technique

    OpenAIRE

    Sousa,R.R.M.; de Araújo, F. O.; J. A. P. da Costa; Brandim,A.S.; R. A. de Brito; C. Alves

    2012-01-01

    Cylindrical samples of AISI 1020, AISI 316, and AISI 420 steels, with different heights, were simultaneously treated by a new technique of ionic nitriding, entitled cathodic cage plasma nitriding (CCPN), in order to evaluate the efficiency of this technique to produce nitrided layers with better properties compared with those obtained using conventional ionic nitriding technique. This method is able to eliminate the edge effect in the samples, promoting a better uniformity of temperature, and...

  17. Properties and Application of Nanocrystalline Poly (vinyl chloride)

    Institute of Scientific and Technical Information of China (English)

    Chuanxi XIONG; Hong YANG; Lijie DONG; Qihong LIU; Qingmin LIU

    2004-01-01

    The structure and properties of nanocrystalline PVC were investigated. The crystalline region of nanocrystalline PVC was observed by TEM to be 80 nm. The melting point of nanocrystalline PVC was found to be 128℃ which is obviously lower than typical PVC (210℃). The X-ray diagram indicated that the crystal existed in nanocrystalline PVC. The evident effect of self-plasticizing and reinforcement appeared when nanocrystalline PVC was added. The optimum amount for self-plasticizing is about 10%. The maximal impact strength of 95.1 kJ/m2 was achieved by adding 20% nanocrystalline PVC and tensile strength with 56.2 MPa which was 122% of pure PVC was obtained after adding 5% nanocrystalline PVC.

  18. Combustion synthesis of bulk nanocrystalline iron alloys

    OpenAIRE

    Licai Fu; Jun Yang; Weimin Liu

    2016-01-01

    The controlled synthesis of large-scale nanocrystalline metals and alloys with predefined architecture is in general a big challenge, and making full use of these materials in applications still requires greatly effort. The combustion synthesis technique has been successfully extended to prepare large-scale nanocrystalline metals and alloys, especially iron alloy, such as FeC, FeNi, FeCu, FeSi, FeB, FeAl, FeSiAl, FeSiB, and the microstructure can be designed. In this issue, recent progress on...

  19. Ultrafast Terahertz Conductivity of Photoexcited Nanocrystalline Silicon

    DEFF Research Database (Denmark)

    Cooke, David; MacDonald, A. Nicole; Hryciw, Aaron;

    2007-01-01

    The ultrafast transient ac conductivity of nanocrystalline silicon films is investigated using time-resolved terahertz spectroscopy. While epitaxial silicon on sapphire exhibits a free carrier Drude response, silicon nanocrystals embedded in glass show a response that is best described by a class......The ultrafast transient ac conductivity of nanocrystalline silicon films is investigated using time-resolved terahertz spectroscopy. While epitaxial silicon on sapphire exhibits a free carrier Drude response, silicon nanocrystals embedded in glass show a response that is best described...

  20. Characterization and Application of Colloidal Nanocrystalline Materials for Advanced Photovoltaics

    Science.gov (United States)

    Bhandari, Khagendra P.

    Solar energy is Earth's primary source of renewable energy and photovoltaic solar cells enable the direct conversion of sunlight into electricity. Crystalline silicon solar cells and modules have dominated photovoltaic technology from the beginning and they now constitute more than 90% of the PV market. Thin film (CdTe and CIGS) solar cells and modules come in second position in market share. Some organic, dye-sensitized and perovskite solar cells are emerging in the market but are not yet in full commercial scale. Solar cells made from colloidal nanocrystalline materials may eventually provide both low cost and high efficiency because of their promising properties such as high absorption coefficient, size tunable band gap, and quantum confinement effect. It is also expected that the greenhouse gas emission and energy payback time from nanocrystalline solar PV systems will also be least compared to all other types of PV systems mainly due to the least embodied energy throughout their life time. The two well-known junction architectures for the fabrication of quantum dot based photovoltaic devices are the Schottky junction and heterojunction. In Schottky junction cells, a heteropartner semiconducting material is not required. A low work function metal is used as the back contact, a transparent conducting layer is used as the front contact, and the layer of electronically-coupled quantum dots is placed between these two materials. Schottky junction solar cells explain the usefulness of nanocrystalline materials for high efficiency heterojunction solar cells. For heterojunction devices, n-type semiconducting materials such as ZnO , CdS or TiO2 have been used as suitable heteropartners. Here, PbS quantum dot solar cells were fabricated using ZnO and CdS semiconductor films as window layers. Both of the heteropartners are sputter-deposited onto TCO coated glass substrates; ZnO was deposited with the substrate held at room temperature and for CdS the substrate was at 250

  1. Low temperature high density plasma nitriding of stainless steel molds for stamping of oxide glasses

    Directory of Open Access Journals (Sweden)

    Aizawa Tatsuhiko

    2016-01-01

    Full Text Available Various kinds of stainless steels have been widely utilized as a die for mold- and direct-stamping processes of optical oxide glasses. Since they suffered from high temperature transients and thermal cycles in practice, they must be surface-treated by dry and wet coatings, or, by plasma nitriding. Martensitic stainless steel mold was first wet plated by the nickel phosphate (NiP, which was unstable at the high temperature stamping condition; and, was easy to crystalize or to fracture by itself. This issue of nuisance significantly lowered the productivity in fabrication of optical oxide-glass elements. In the present paper, the stainless steel mold was surface-treated by the low-temperature plasma nitriding. The nitrided layer by this surface modification had higher nitrogen solute content than 4 mass%; the maximum solid-solubility of nitrogen is usually 0.1 mass% in the equilibrium phase diagram. Owing to this solid-solution with high nitrogen concentration, the nitrided layer had high hardness over 1400 HV within its thickness of 50 μm without any formation of nitrides after plasma nitriding at 693 K for 14.4 ks. This plasma-nitrided mold was utilized for mold-stamping of two colored oxide glass plates at 833 K; these plates were successfully deformed and joined into a single glass plate by this stamping without adhesion or galling of oxide glasses onto the nitrided mold surface.

  2. Resistance of Silicon Nitride Turbine Components to Erosion and Hot Corrosion/oxidation Attack

    Science.gov (United States)

    Strangmen, Thomas E.; Fox, Dennis S.

    1994-01-01

    Silicon nitride turbine components are under intensive development by AlliedSignal to enable a new generation of higher power density auxiliary power systems. In order to be viable in the intended applications, silicon nitride turbine airfoils must be designed for survival in aggressive oxidizing combustion gas environments. Erosive and corrosive damage to ceramic airfoils from ingested sand and sea salt must be avoided. Recent engine test experience demonstrated that NT154 silicon nitride turbine vanes have exceptional resistance to sand erosion, relative to superalloys used in production engines. Similarly, NT154 silicon nitride has excellent resistance to oxidation in the temperature range of interest - up to 1400 C. Hot corrosion attack of superalloy gas turbine components is well documented. While hot corrosion from ingested sea salt will attack silicon nitride substantially less than the superalloys being replaced in initial engine applications, this degradation has the potential to limit component lives in advanced engine applications. Hot corrosion adversely affects the strength of silicon nitride in the 850 to 1300 C range. Since unacceptable reductions in strength must be rapidly identified and avoided, AlliedSignal and the NASA Lewis Research Center have pioneered the development of an environmental life prediction model for silicon nitride turbine components. Strength retention in flexure specimens following 1 to 3300 hour exposures to high temperature oxidation and hot corrosion has been measured and used to calibrate the life prediction model. Predicted component life is dependent upon engine design (stress, temperature, pressure, fuel/air ratio, gas velocity, and inlet air filtration), mission usage (fuel sulfur content, location (salt in air), and times at duty cycle power points), and material parameters. Preliminary analyses indicate that the hot corrosion resistance of NT154 silicon nitride is adequate for AlliedSignal's initial engine

  3. Deposition of titanium nitride layers by electric arc - Reactive plasma spraying method

    Science.gov (United States)

    Şerban, Viorel-Aurel; Roşu, Radu Alexandru; Bucur, Alexandra Ioana; Pascu, Doru Romulus

    2013-01-01

    Titanium nitride (TiN) is a ceramic material which possesses high mechanical properties, being often used in order to cover cutting tools, thus increasing their lifetime, and also for covering components which are working in corrosive environments. The paper presents the experimental results on deposition of titanium nitride coatings by a new combined method (reactive plasma spraying and electric arc thermal spraying). In this way the advantages of each method in part are combined, obtaining improved quality coatings in the same time achieving high productivity. Commercially pure titanium wire and C45 steel as substrate were used for experiments. X-ray diffraction analysis shows that the deposited coatings are composed of titanium nitride (TiN, Ti2N) and small amounts of Ti3O. The microstructure of the deposited layers, investigated both by optical and scanning electron microscopy, shows that the coatings are dense, compact, without cracks and with low porosity. Vickers microhardness of the coatings presents maximum values of 912 HV0.1. The corrosion tests in 3%NaCl solution show that the deposited layers have a high corrosion resistance compared to unalloyed steel substrate.

  4. Theoretical Compton profile of diamond, boron nitride and carbon nitride

    Science.gov (United States)

    Aguiar, Julio C.; Quevedo, Carlos R.; Gomez, José M.; Di Rocco, Héctor O.

    2017-09-01

    In the present study, we used the generalized gradient approximation method to determine the electron wave functions and theoretical Compton profiles of the following super-hard materials: diamond, boron nitride (h-BN), and carbon nitride in its two known phases: βC3N4 and gC3N4 . In the case of diamond and h-BN, we compared our theoretical results with available experimental data. In addition, we used the Compton profile results to determine cohesive energies and found acceptable agreement with previous experiments.

  5. Research on the Cutting Performance of Cubic Boron Nitride Tools

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    There were only two kinds of superhard tool material at the past, i.e. diamond and cubic boron nitride (CBN). Manmade diamond and CBN are manufactured by the middle of 20th century. Various manufacturing methods and manmade superhard materials were developed later. They were widely used in different industry and science areas. Recently, a new kind of superhard tool material, C 3N 4 coating film, had been developed. American physical scientists, A. M. Liu and M. L. Cohen, designed a new kind of inorganic c...

  6. Galvanic couples of 316L steel with Ti and ion plated Ti and TiN coatings in Ringer's solutions.

    Science.gov (United States)

    Gluszek, J; Jedrkowiak, J; Markowski, J; Masalski, J

    1990-07-01

    Steel 316L was coated with titanium or titanium nitride by ion plating. The tightness of the coatings was examined electro-chemically. The galvanic effects for the galvanic couples steel-titanium, steel-titanium-coated steel and steel-titanium nitride-coated steel were studied. It was found that both titanium and titanium nitride coatings were non-porous in Ringer's solution; titanium served as an anode in the couple steel-titanium; it was oxidized according to the logarithmic law. For the other two couples, the coatings were the cathodes. The rate of dissolution of steel in these couples, was however, smaller than expected, owing to a strong polarization of the coatings. The potential of the couple was similar to that of steel.

  7. Mathematical Modelling of Nitride Layer Growth of Low Temperature Gas and Plasma Nitriding of AISI 316L

    Directory of Open Access Journals (Sweden)

    Triwiyanto A.

    2014-07-01

    Full Text Available This paper present mathematical model which developed to predict the nitrided layer thickness (case depth of gas nitrided and plasma nitrided austenitic stainless steel according to Fick’s first law for pure iron by adapting and manipulating the Hosseini’s model to fit the diffusion mechanism where nitrided structure formed by nitrided AISI 316L austenitic stainless steel. The mathematical model later tested against various actual gas nitriding and plasma nitriding experimental results with varying nitriding temperature and nitriding duration to see whether the model managed to successfully predict the nitrided layer thickness. This model predicted the coexistence of ε-Fe2-3N and γ΄-Fe4N under the present nitriding process parameters. After the validation process, it is proven that the mathematical model managed to predict the nitrided layer growth of the gas nitrided and plasma nitrided of AISI 316L SS up to high degree of accuracy.

  8. Carbon nitrides: synthesis and characterization of a new class of functional materials.

    Science.gov (United States)

    Miller, T S; Jorge, A Belen; Suter, T M; Sella, A; Corà, F; McMillan, P F

    2017-06-21

    Carbon nitride compounds with high N : C ratios and graphitic to polymeric structures are being investigated as potential next-generation materials for incorporation in devices for energy conversion and storage as well as for optoelectronic and catalysis applications. The materials are built from C- and N-containing heterocycles with heptazine or triazine rings linked via sp(2)-bonded N atoms (N(C)3 units) or -NH- groups. The electronic, chemical and optical functionalities are determined by the nature of the local to extended structures as well as the chemical composition of the materials. Because of their typically amorphous to nanocrystalline nature and variable composition, significant challenges remain to fully assess and calibrate the structure-functionality relationships among carbon nitride materials. It is also important to devise a useful and consistent approach to naming the different classes of carbon nitride compounds that accurately describes their chemical and structural characteristics related to their functional performance. Here we evaluate the current state of understanding to highlight key issues in these areas and point out new directions in their development as advanced technological materials.

  9. Nanocarbon Allotropes-Graphene and Nanocrystalline Diamond-Promote Cell Proliferation.

    Science.gov (United States)

    Verdanova, Martina; Rezek, Bohuslav; Broz, Antonin; Ukraintsev, Egor; Babchenko, Oleg; Artemenko, Anna; Izak, Tibor; Kromka, Alexander; Kalbac, Martin; Hubalek Kalbacova, Marie

    2016-05-01

    Two profoundly different carbon allotropes - nanocrystalline diamond and graphene - are of considerable interest from the viewpoint of a wide range of biomedical applications including implant coating, drug and gene delivery, cancer therapy, and biosensing. Osteoblast adhesion and proliferation on nanocrystalline diamond and graphene are compared under various conditions such as differences in wettability, topography, and the presence or absence of protein interlayers between cells and the substrate. The materials are characterized in detail by means of scanning electron microscopy, atomic force microscopy, photoelectron spectroscopy, Raman spectroscopy, and contact angle measurements. In vitro experiments have revealed a significantly higher degree of cell proliferation on graphene than on nanocrystalline diamond and a tissue culture polystyrene control material. Proliferation is promoted, in particular, by hydrophobic graphene with a large number of nanoscale wrinkles independent of the presence of a protein interlayer, i.e., substrate fouling is not a problematic issue in this respect. Nanowrinkled hydrophobic graphene, thus, exhibits superior characteristics for those biomedical applications where high cell proliferation is required under differing conditions.

  10. Electrochromic devices based on wide band-gap nanocrystalline semiconductors functionalized with mononuclear charge transfer compounds

    DEFF Research Database (Denmark)

    Biancardo, M.; Argazzi, R.; Bignozzi, C.A.

    2006-01-01

    A series of ruthenium and iron mononuclear complexes were prepared and their spectroeletrochemical behavior characterized oil Optically Transparent Thin Layer Electrodes (OTTLE) and on Fluorine Doped SnO2 (FTO) conductive glasses coated with Sb-doped nanocrystalline SnO2. These systems display...... a reversible electrochemical response and offer potential application in electrochromic devices. On SnO2 films distinct spectral changes are observed in a narrow potential range (-0.5/0.9 V vs SCE) with switching times of the order of 0.8 s. (c) 2005 Elsevier B.V. All rights reserved....

  11. III-Nitride nanowire optoelectronics

    Science.gov (United States)

    Zhao, Songrui; Nguyen, Hieu P. T.; Kibria, Md. G.; Mi, Zetian

    2015-11-01

    Group-III nitride nanowire structures, including GaN, InN, AlN and their alloys, have been intensively studied in the past decade. Unique to this material system is that its energy bandgap can be tuned from the deep ultraviolet (~6.2 eV for AlN) to the near infrared (~0.65 eV for InN). In this article, we provide an overview on the recent progress made in III-nitride nanowire optoelectronic devices, including light emitting diodes, lasers, photodetectors, single photon sources, intraband devices, solar cells, and artificial photosynthesis. The present challenges and future prospects of III-nitride nanowire optoelectronic devices are also discussed.

  12. Reactive plasma synthesis of nanocrystalline ceramic oxides

    Science.gov (United States)

    Sreekumar, K. P.; Vijay, M.; Thiyagarajan, T. K.; Krishnan, K.; Ananthapadmanabhan, P. V.

    2010-02-01

    Reactive plasma synthesis is an attractive route to synthesize nanocrystalline materials. A 40 kW DC non-transferred arc plasma reactor has been designed and developed in our laboratory for synthesis of nanocrystalline materials. The main components of the plasma reactor include a 40 kW DC plasma generator or plasma torch, water-cooled reactor segment, product collection facility, DC power supply, cooling-water system and exhaust gas vent. The system has been used to synthesize nano-crystalline oxides of aluminium, titanium and zirconium. Aluminium metal powder was used as the starting material to synthesize alumina. The hydrides of Ti and Zr were used as the precursor for synthesis of nanocrystalline titania and zirconia respectively. The precursor powders were injected into the thermal plasma jet and were allowed to react with oxygen injected downstream the jet. The precursor powder particles were oxidized 'in-flight' to form nano-sized powder of the respective metal, which deposited on the walls of the reactor and collector assembly. Various analytical tools were used to characterized the products.

  13. Multiphase Nanocrystalline Ceramic Concept for Nuclear Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Mecartnery, Martha [Univ. of California, Irvine, CA (United States); Graeve, Olivia [Univ. of California, San Diego, CA (United States); Patel, Maulik [Univ. of Liverpool (United Kingdom)

    2017-05-25

    The goal of this research is to help develop new fuels for higher efficiency, longer lifetimes (higher burn-up) and increased accident tolerance in future nuclear reactors. Multiphase nanocrystalline ceramics will be used in the design of simulated advanced inert matrix nuclear fuel to provide for enhanced plasticity, better radiation tolerance, and improved thermal conductivity

  14. Tribological properties of boron nitride synthesized by ion beam deposition

    Science.gov (United States)

    Miyoshi, K.; Buckley, D. H.; Spalvins, T.

    1985-01-01

    The adhesion and friction behavior of boron nitride films on 440 C bearing stainless steel substrates was examined. The thin films containing the boron nitride were synthesized using an ion beam extracted from a borazine plasma. Sliding friction experiments were conducted with BN in sliding contact with itself and various transition metals. It is indicated that the surfaces of atomically cleaned BN coating film contain a small amount of oxides and carbides, in addition to boron nitride. The coefficients of friction for the BN in contact with metals are related to the relative chemical activity of the metals. The more active the metal, the higher is the coefficient of friction. The adsorption of oxygen on clean metal and BN increases the shear strength of the metal - BN contact and increases the friction. The friction for BN-BN contact is a function of the shear strength of the elastic contacts. Clean BN surfaces exhibit relatively strong interfacial adhesion and high friction. The presence of adsorbates such as adventitious carbon contaminants on the BN surfaces reduces the shear strength of the contact area. In contrast, chemically adsorbed oxygen enhances the shear strength of the BN-BN contact and increases the friction.

  15. Field emission from open ended aluminum nitride nanotubes

    Science.gov (United States)

    Tondare, V. N.; Balasubramanian, C.; Shende, S. V.; Joag, D. S.; Godbole, V. P.; Bhoraskar, S. V.; Bhadbhade, M.

    2002-06-01

    This letter reports the field emission measurements from the nanotubes of aluminum nitride which were synthesized by gas phase condensation using the solid-vapor equilibria. A dc arc plasma reactor was used for producing the vapors of aluminum in a reactive nitrogen atmosphere. Nanoparticles and nanotubes of aluminum nitride were first characterized by transmission electron microscope and tube dimensions were found to be varying from 30 to 200 nm in diameter and 500 to 700 nm in length. These tubes were mixed with nanoparticles of size range between 5 and 200 nm in diameter. Tungsten tips coated with these nanoparticles and tubes were used as a field emitter. The field emission patterns display very interesting features consisting of sharp rings which were often found to change their shapes. The patterns are attributed to the open ended nanotubes of aluminum nitride. A few dot patterns corresponding to the nanoparticles were also seen to occur. The Fowler-Nordheim plots were seen to be nonlinear in nature, which reflects the semi-insulating behavior of the emitter. The field enhancement factor is estimated to be 34 500 indicating that the field enhancement due to the nanometric size of the emitter is an important cause for the observed emission.

  16. Boron Nitride Nanoribbons from Exfoliation of Boron Nitride Nanotubes

    Science.gov (United States)

    Hung, Ching-Cheh; Hurst, Janet; Santiago, Diana

    2017-01-01

    Two types of boron nitride nanotubes (BNNTs) were exfoliated into boron nitride nanoribbons (BNNR), which were identified using transmission electron microscopy: (1) commercial BNNTs with thin tube walls and small diameters. Tube unzipping was indicated by a large decrease of the sample's surface area and volume for pores less than 2 nm in diameter. (2) BNNTs with large diameters and thick walls synthesized at NASA Glenn Research Center. Here, tube unraveling was indicated by a large increase in external surface area and pore volume. For both, the exfoliation process was similar to the previous reported method to exfoliate commercial hexagonal boron nitride (hBN): Mixtures of BNNT, FeCl3, and NaF (or KF) were sequentially treated in 250 to 350 C nitrogen for intercalation, 500 to 750 C air for exfoliation, and finally HCl for purification. Property changes of the nanosized boron nitride throughout this process were also similar to the previously observed changes of commercial hBN during the exfoliation process: Both crystal structure (x-ray diffraction data) and chemical properties (Fourier-transform infrared spectroscopy data) of the original reactant changed after intercalation and exfoliation, but most (not all) of these changes revert back to those of the reactant once the final, purified products are obtained.

  17. Homogeneous dispersion of gallium nitride nanoparticles in a boron nitride matrix by nitridation with urea.

    Science.gov (United States)

    Kusunose, Takafumi; Sekino, Tohru; Ando, Yoichi

    2010-07-01

    A Gallium Nitride (GaN) dispersed boron nitride (BN) nanocomposite powder was synthesized by heating a mixture of gallium nitrate, boric acid, and urea in a hydrogen atmosphere. Before heat treatment, crystalline phases of urea, boric acid, and gallium nitrate were recognized, but an amorphous material was produced by heat treatment at 400 degrees C, and then was transformed into GaN and turbostratic BN (t-BN) by further heat treatment at 800 degrees C. TEM obsevations of this composite powder revealed that single nanosized GaN particles were homogeneously dispersed in a BN matrix. Homogeneous dispersion of GaN nanoparticles was thought to be attained by simultaneously nitriding gallium nitrate and boric acid to GaN and BN with urea.

  18. 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.

  19. Enhanced non-radiative energy transfer in hybrid III-nitride structures

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R. M.; Athanasiou, M.; Bai, J.; Liu, B.; Wang, T., E-mail: t.wang@sheffield.ac.uk [Department of Electrical and Electronic Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom)

    2015-09-21

    The effect of surface states has been investigated in hybrid organic/inorganic white light emitting structures that employ high efficiency, nearfield non-radiative energy transfer (NRET) coupling. The structures utilize blue emitting InGaN/GaN multiple quantum well (MQW) nanorod arrays to minimize the separation with a yellow emitting F8BT coating. Surface states due to the exposed III-nitride surfaces of the nanostructures are found to reduce the NRET coupling rate. The surface states are passivated by deposition of a silicon nitride layer on the III-nitride nanorod surface leading to reduced surface recombination. A low thickness surface passivation is shown to increase the NRET coupling rate by 4 times compared to an un-passivated hybrid structure. A model is proposed to explain the increased NRET rate for the passivated hybrid structures based on the reduction in surface electron depletion of the passivated InGaN/GaN MQW nanorods surfaces.

  20. Enhanced non-radiative energy transfer in hybrid III-nitride structures

    Science.gov (United States)

    Smith, R. M.; Athanasiou, M.; Bai, J.; Liu, B.; Wang, T.

    2015-09-01

    The effect of surface states has been investigated in hybrid organic/inorganic white light emitting structures that employ high efficiency, nearfield non-radiative energy transfer (NRET) coupling. The structures utilize blue emitting InGaN/GaN multiple quantum well (MQW) nanorod arrays to minimize the separation with a yellow emitting F8BT coating. Surface states due to the exposed III-nitride surfaces of the nanostructures are found to reduce the NRET coupling rate. The surface states are passivated by deposition of a silicon nitride layer on the III-nitride nanorod surface leading to reduced surface recombination. A low thickness surface passivation is shown to increase the NRET coupling rate by 4 times compared to an un-passivated hybrid structure. A model is proposed to explain the increased NRET rate for the passivated hybrid structures based on the reduction in surface electron depletion of the passivated InGaN/GaN MQW nanorods surfaces.