Measurement of residual stress in plasma-sprayed composite coatings with graded and uniform compositions

Energy Technology Data Exchange (ETDEWEB)

Kesler, O.; Suresh, S. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Matejicek, J.; Sampath, S.

1999-10-01

Residual stresses in plasma sprayed composite coatings were studied experimentally by both curvature and neutron diffraction measurements. Graded and uniform composite coatings, consisting of nickel + alumina and NiCrAlY + yttria-stabilized zirconia, were investigated. This paper briefly summarizes our recent work dealing with the effects of coating thickness, composition, and material properties on the evolution of residual stresses in coatings. Analysis of the results allowed in some cases the separation of the quenching stress and thermal stress contributions to the final residual stress, as well as the determination of the through-thickness stress profile from measurements of different thickness specimens. In the ceramic-metal composites, it was found that the thermal mismatch stress plays a dominant role in the ceramic phase, whereas the stress in the metallic phase is mostly dominated by quenching stress. The residual stress measurement methods employed here were found to be complementary, in that each can provide unique information about the stress state. Through-thickness stress profiles in graded coatings were determined with high spatial resolution by the curvature method, and determination of the stress in each separate phase of a composite was made by neutron diffraction. (orig.) 14 refs.

Articulating spacers used in two-stage revision of infected hip and knee prostheses abrade with time.

Science.gov (United States)

Fink, Bernd; Rechtenbach, Annett; Büchner, Hubert; Vogt, Sebastian; Hahn, Michael

2011-04-01

Articulating spacers used in two-stage revision surgery of infected prostheses have the potential to abrade and subsequently induce third-body wear of the new prosthesis. We asked whether particulate material abraded from spacers could be detected in the synovial membrane 6 weeks after implantation when the spacers were removed for the second stage of the revision. Sixteen hip spacers (cemented prosthesis stem articulating with a cement cup) and four knee spacers (customized mobile cement spacers) were explanted 6 weeks after implantation and the synovial membranes were removed at the same time. The membranes were examined by xray fluorescence spectroscopy, xray diffraction for the presence of abraded particles originating from the spacer material, and analyzed in a semiquantitative manner by inductively coupled plasma mass spectrometry. Histologic analyses also were performed. We found zirconium dioxide in substantial amounts in all samples, and in the specimens of the hip synovial lining, we detected particles that originated from the metal heads of the spacers. Histologically, zirconium oxide particles were seen in the synovial membrane of every spacer and bone cement particles in one knee and two hip spacers. The observations suggest cement spacers do abrade within 6 weeks. Given the presence of abrasion debris, we recommend total synovectomy and extensive lavage during the second-stage reimplantation surgery to minimize the number of abraded particles and any retained bacteria.

Ageing kinetics and strength of airborne-particle abraded 3Y-TZP ceramics.

Science.gov (United States)

Cotič, Jasna; Jevnikar, Peter; Kocjan, Andraž

2017-07-01

The combined effects of alumina airborne-particle abrasion and prolonged in vitro ageing on the flexural strength of 3Y-TZP ceramic have been studied. The aim was to identify the different effects on the surface and subsurface regions that govern the performance of this popular bioceramic known for its susceptibility to low-temperature degradation (LTD). As-sintered or airborne-particle abraded 3Y-TZP discs were subjected to ageing at 134°C for up to 480h. Biaxial flexural strength was measured and the relative amount of monoclinic phase determined using X-ray diffraction. The transformed zone depth (TZD) was observed on cross-sections with scanning electron microscopy coupled with a focused ion beam. Segmented linear regression was used to analyze the flexural strength and TZD as functions of the ageing time. A two-step linear ageing kinetics was detected in airborne-particle abraded specimens, reflecting the different microstructures through which the LTD proceeds into the bulk. A 10μm thick altered zone under the abraded surface was involved in both the surface strengthening and the increased ageing resistance. When the zone was annihilated by the LTD, the strength of the ceramic specimens and the speed of LTD returned to the values measured before abrasion. Even at prolonged ageing times, the strength of abraded groups was not lower than that of as-sintered groups. Both the ageing kinetics and the flexural strength were prominently affected by airborne-particle abrasion, which altered the subsurface microstructure and phase composition. Airborne-particle abrasion was not harmful to the 3Y-TZP ceramics' stability. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Influences of Processing and Fatigue Cycling on Residual Stresses in a NiCrY-Coated Powder Metallurgy Disk Superalloy

Science.gov (United States)

Gabb, T. P.; Rogers, R. B.; Nesbitt, J. A.; Miller, R. A.; Puleo, B. J.; Johnson, D.; Telesman, J.; Draper, S. L.; Locci, I. E.

2017-11-01

Oxidation and corrosion can attack superalloy disk surfaces exposed to increasing operating temperatures in some turbine engine environments. Any potential protective coatings must also be resistant to harmful fatigue cracking during service. The objective of this study was to investigate how residual stresses evolve in one such coating. Fatigue specimens of a powder metallurgy-processed disk superalloy were coated with a NiCrY coating, shot peened, and then subjected to fatigue in air at room and high temperatures. The effects of this processing and fatigue cycling on axial residual stresses and other aspects of the coating were assessed. While shot peening did induce beneficial compressive residual stresses in the coating and substrate, these stresses relaxed in the coating with subsequent heating. Several cast alloys having compositions near the coating were subjected to thermal expansion and tensile stress relaxation tests to help explain this response of residual stresses in the coating. For the coated fatigue specimens, this response contributed to earlier cracking of the coating than for the uncoated surface during long intervals of cycling at 760 °C. Yet, substantial compressive residual stresses still remained in the substrate adjacent to the coating, which were sufficient to suppress fatigue cracking there. The coating continued to protect the substrate from hot corrosion pitting, even after fatigue cracks initiated in the coating.

Temperature dependence of residual stress in TiC coated Mo

International Nuclear Information System (INIS)

Yoshizawa, I.; Fukutomi, M.; Kamada, K.

1984-01-01

The effects of fabrication temperature and heat treatment on the residual stress in TiC coated Mo have been studied by using X-ray diffractometry. TiC coatings on Mo single crystal substrates with (100) and (111) surfaces were carried out with the Activated Reactive Evaporation (ARE) method. It was found that all Mo substrates measured show tensile residual stresses, and their values decrease as the fabrication temperature increases from 300 to 700 0 C. On the other hand, TiC films measured showed compressive residual stresses, for both TiC/Mo(100) and TiC/Mo(111) specimens. These compressive stresses also decreased with increasing the fabrication temperature. The residual stresses measured were higher in TiC/Mo(100) than in TiC/Mo(111). It was found that the compressive stresses in as-grown TiC films change to the tensile stresses after annealing at 1700 0 C for 30 min. The preferred orientations of TiC films were observed to depend on the fabrication temperature. However, no epitaxial growth of TiC films was found as far as the present experiment was concerned. (orig.)

Powder addition assessment of manganese residue ceramic matrix coating

International Nuclear Information System (INIS)

Conceicao, A.C.R. da; Santos, O.C.; Leao, M.A.

2016-01-01

The use of recycled materials in the composition of new products follows the production's worldwide trending, meeting new technological requirements and environmental concerns. This work aims to utilize the residue of manganese dust on ceramic mass for the production of ceramic coating. The raw materials were characterized by both x-ray fluorescence and diffraction. The powder residue added to clay in the percentage of 0%, 5%, 10% and 15% (measured in weight) was compressed by a uniaxial pressing of 30MPa and the sintering temperatures were 900°, 1000° and 1100°. The samples were analysed in relation to flexural strength, bulk density, water absorption and linear shrinkage. The microstructural variation was also analysed by x-ray diffraction and electron microscopy. The results showed that there is a viability for the production of porcelain ceramic coating (A3 and A4 formulations) and stoneware (A2 formulation) according to the specification of technical standards. author)

Residual stress in the first wall coating materials of TiC and TiN for fusion reactor

International Nuclear Information System (INIS)

Qiu Shaoyu

1997-01-01

Residual stresses measurement in the first wall coating of a fusion reactor of TiC and TiN films by X-ray diffraction 'sin 2 ψ methods' were described. The authors have studied on the effect of conditions of specimen preparation (such as coating method, substrate materials, film thickness and deposition temperature) on the residual stress of TiC and TiN films coated onto Mo, 316LSS and Pocographite by chemical vapor deposition (CVD) and physical vapor deposition (PVD) method. All films prepared in this study were found to have a compressive stresses and the CVD method gave lower residual stress than PVD method. TiC film coated on Mo substrate at 1100 degree C by CVD method showed that residual stress as the film thickness was raised from 14 μm to 60 μm, on the other hand, residual stress by PVD method exhibited a high compressive stresses, this kind of stress was principally the intrinsic stress, and a marked decrease in the residual with raising the deposition temperature (200 degree C∼650 degree C) was demonstrated. Origins of the residual stress were discussed by correlation with differences between thermal expansion coefficients, and also with fabrication methods

State of residual stress in laser-deposited ceramic composite coatings on aluminum alloys

NARCIS (Netherlands)

Kadolkar, P. B.; Watkins, T. R.; De Hosson, J. Th. M.; Kooi, B. J.; Dahotre, N. B.

The nature and magnitude of the residual stresses within laser-deposited titanium carbide (TiC) coatings on 2024 and 6061 aluminum (Al) alloys were investigated. Macro- and micro-stresses within the coatings were determined using an X-ray diffraction method. Owing to increased debonding between the

Design and simulation of thermal residual stresses of coatings on WC-Co cemented carbide cutting tool substrate

International Nuclear Information System (INIS)

Li, Anhai; Zhao, Jun; Zang, Jian; Zheng, Wei

2016-01-01

Large thermal residual stresses in coatings during the coating deposition process may easily lead to coating delamination of coated carbide tools in machining. In order to reduce the possibility of coating delamination during the tool failure process, a theoretical method was proposed and a numerical method was constructed for the coating design of WC-Co cemented carbide cutting tools. The thermal residual stresses of multi-layered coatings were analytically modeled based on equivalent parameters of coating properties, and the stress distribution of coatings are simulated by Finite element method (FEM). The theoretically calculated results and the FEM simulated results were verified and in good agreement with the experimental test results. The effects of coating thickness, tool substrate, coating type and interlayer were investigated by the proposed geometric and FEM model. Based on the evaluations of matchability of tool substrate and tool coatings, the basic principles of tool coating design were proposed. This provides theoretical basis for the selection and design of coatings of cutting tools in high-speed machining

Effect of No-Clean Flux Residues on the Performance of Acrylic Conformal Coating in Aggressive Environments

DEFF Research Database (Denmark)

Rathinavelu, Umadevi; Jellesen, Morten S.; Møller, Per

2012-01-01

at various temperatures was quantified using ion chromatography by extracting the residue, and surface morphology of the residues was investigated using optical microscopy. The flux residue in general consists of both resin and activator components such as carboxylic acids. Coated samples with flux residues...

State of residual stress in laser-deposited ceramic composite coatings on aluminum alloys

OpenAIRE

Kadolkar, P. B.; Watkins, T. R.; De Hosson, J. Th. M.; Kooi, B. J.; Dahotre, N. B.

2007-01-01

The nature and magnitude of the residual stresses within laser-deposited titanium carbide (TiC) coatings on 2024 and 6061 aluminum (Al) alloys were investigated. Macro- and micro-stresses within the coatings were determined using an X-ray diffraction method. Owing to increased debonding between the coating and the substrate, the macro-stresses were found to be compressive and to decrease in magnitude with increasing processing speed. The origin of the macro- and micro-stresses is discussed. T...

Residual stress determination in PECVD TiN coatings by X-ray diffraction: a parametric study

DEFF Research Database (Denmark)

Thomsen, N.B.; Horsewell, Andy; Mogensen, K.S.

1998-01-01

The main objective of this research is to study the residual macroscopic stress in titanium-nitride, TiN, coatings deposited onto a tool steer substrate. The measurements were performed with a theta-theta decoupled X-ray diffractometer. The coatings were manufactured using an industrial pulsed...

Using of sawing quartzite fine residual for obtaining ceramic coating

International Nuclear Information System (INIS)

Nobrega, L.F.P.M.; Souza, M.M.

2016-01-01

Quartzite is a metamorphic rock that is consisting mainly of quartz. In Paraiba there is a mining activity of this rock, in the region of Varzea and Junco do Serido especially where many wastes are created, including the sawing residue. The objective is to use the waste cited as the ceramic component coating mass, thereby replacing the quartz. Initially, the raw materials samples were taken and the chemical analysis was done of them. This passed the comminution process to achieve the required minimum particle size. After this, a formulation which added the residue in ceramic mass was made. The specimens were subjected to sintering and it was later made physical tests according to NBR 13818. The results show that the residue can replace the quartz ceramic mass successfully, but not as good as the original raw material. (author)

The evaluation of hierarchical structured superhydrophobic coatings for the alleviation of insect residue to aircraft laminar flow surfaces

Energy Technology Data Exchange (ETDEWEB)

Kok, Mariana [Department of Mechanical, Aeronautical and Biomedical Engineering, University of Limerick, Limerick (Ireland); Materials and Surface Science Institute, University of Limerick, Limerick (Ireland); Young, Trevor M., E-mail: Trevor.Young@ul.ie [Department of Mechanical, Aeronautical and Biomedical Engineering, University of Limerick, Limerick (Ireland); Materials and Surface Science Institute, University of Limerick, Limerick (Ireland)

2014-09-30

Surface contamination caused by insects on laminar flow wing surfaces causes a disruption of the flow, resulting in an increase in drag and fuel consumption. Consequently, the use of superhydrophobic coatings to mitigate insect residue adhesion was investigated. A range of hierarchical superhydrophobic coatings with different surface chemistry and topography was examined. Candidate coatings were characterized in terms of their morphology and hydrophobic properties by scanning electron microscopy (SEM) and static and dynamic contact angle measurements, respectively. Arithmetic mean surface roughness (R{sub a}) values were measured using profilometry. Only superhydrophobic coatings with a specific topography showed complete mitigation against insect residue adhesion. A surface which exhibited a specific microstructure (R{sub a} = 5.26 μm) combined with a low sliding angle (SA = 7.6°) showed the best anti-contamination properties. The dynamics of an insect impact event and its influence on the wetting and adhesion mechanisms of insect residue to a surface were discussed.

3D-simulation of residual stresses in TBC plasma sprayed coating

International Nuclear Information System (INIS)

Kundas, S.; Kashko, T.; Hurevich, V.E.; Lugscheider, E.; Hayn, G. von; Ilyuschenko, A.

2001-01-01

Thermal barrier coatings (TBC) are used in gas turbine technology in order to protect against overheating of the nickel alloy turbine blades. This coatings allows to increase turbine inlet temperatures and improve their efficiency. Plasma spraying processes are widely used since several years in thermal barrier coating technology. Although the plasma spraying process of TBC's is largely successful, a fundamental understanding of the process parameters influencing the TBC microstructure and mechanical properties is necessary. But this investigation has received much less attention so they could lead to considerable advances in performance of plasma sprayed thermal barrier coatings. The main reason of this mate is difficulties in experimental investigation of high temperature and high velocity process. One of the most effective ways to accelerate the process optimization is the application of computer simulation for the modeling of plasma spraying. This enables the achievement of a maximum of information about the investigated process by carrying out a minimum number of experiments. The main problem of plasma spray TBC coatings is crack information during the deposition process and coating cooling. The reasons for this are quenched and residual stresses in the coating-substrate system, and peculiarities of TBC coating properties. The problem of deposition and solidification of plasma sprayed coatings have received little attention to date and remains one of the unintelligible parts of process. A fundamental understanding of heat transfer in the coating-substrate system and particles deformation processes are, however, critical for the prediction of the microstructural characteristics of the deposited coatings, the understanding of the mechanisms involved in formation of thermal stresses and defects (cracks, debonding etc.). (author)

Tailoring the Surface Properties of Coatings Through Self-Stratification

Science.gov (United States)

2016-10-13

gold before imaging. The gold coated samples were then observed 8 under 250, 1000 and 3000 magnifications. The scans obtained for the abraded...Octamethylcyclotetrasiloxane (D4), bis(3-aminopropyl)-tetramethyldisiloxane (BAPTMDS) were purchased from Gelest, Inc. Benzyltrimethylammonium hydroxide (in 40% methanol) was...purchased from Sigma Aldrich. The cyclic siloxane monomer D4 (1200 g) and benzyltrimethyl ammonium hydroxide (3.12 g) catalyst were combined in a

Characterization and analyses on micro-hardness, residual stress and microstructure in laser cladding coating of 316L stainless steel subjected to massive LSP treatment

Energy Technology Data Exchange (ETDEWEB)

Luo, K.Y.; Jing, X.; Sheng, J. [School of Mechanical Engineering, Jiangsu University, Zhenjiang, 212013 (China); Sun, G.F. [School of Mechanical Engineering, Southeast University, Nanjing, 211189 (China); Yan, Z. [School of Mechanical Engineering, Jiangsu University, Zhenjiang, 212013 (China); Lu, J.Z., E-mail: jzlu@ujs.edu.cn [School of Mechanical Engineering, Jiangsu University, Zhenjiang, 212013 (China)

2016-07-15

The effects of massive laser shock peening (LSP) treatment on micro-hardness, residual stress and microstructure in four different zones of laser cladding coating was investigated. Furthermore, micro-hardness curves and residual stress distributions with and without massive LSP treatment were presented and compared, and typical microstructure in different zones of both coatings were characterized by transmission electron microscope (TEM) and cross-sectional optical microscope (OM) observations. Results and analyses showed that massive LSP treatment had an important influence on micro-hardness and residual stress of the cladding coating. Special attempt was made to the effects of massive LSP treatment on microstructure in three zones of the cladding coating. In addition, the underlying mechanism of massive LSP treatment on microstructure and mechanical properties of the cladding coating was revealed clearly. - Highlights: • Micro-hardness and residual stress curves of both coatings were presented and compared. • Typical microstructure in different zones of both coatings were characterized and analyzed. • LSP causes increased micro-activities, and induces plastic deformation layer in three zones. • Underlying mechanism of LSP on mechanical properties of cladding coating was revealed.

Effect of dissolution/precipitation on the residual stress redistribution of plasma-sprayed hydroxyapatite coating on titanium substrate in simulated body fluid (SBF).

Science.gov (United States)

Rakngarm Nimkerdphol, Achariya; Otsuka, Yuichi; Mutoh, Yoshiharu

2014-08-01

The residual stress distributions in hydroxyapatite (HAp) coating with and without mixed hydroxyapatite/titanium (HAp/Ti) bond coating on commercially pure Titanium substrate (cp-Ti) were evaluated by Raman piezo-spectroscopy analysis. The Raman shifted position 962cm(-1), which is the symmetrical stretching of surrounded oxygen atoms with phosphorous atom ( [Formula: see text] ), was referred to analyses of stress dependency. The piezo-spectroscopic coefficient, which is a Raman shift value per stress (cm(-1)/GPa), was fitted from the result of four-points bending test of rectangular HAp bar and as-sprayed HAp on Zn plate. The calculated values were 3.89cm(-1)/GPa for the former and 7.11cm(-1)/GPa for the latter. By using these calibrations, the compressive residual stress in HAp coating with HAp/Ti bond coating (HA-B) has been found to be distributed in the range of -137MPa to -75MPa. For the heat-treated HAp coating (HA-B-HT) specimen, the compressive residual stresses placed in the range of -40--22MPa. The changes in the values of residual stress of the HAp coating after immersion in SBF were also evaluated. The residual stress in HA-WB specimens tend to change from compressive to tensile after 30 days immersion. The HA-B-HT specimens exhibited similar behavior and reached to zero stress after the immersion. The mechanism of the changes in residual stress would be the effect of stress redistribution around melted calcium phosphate particles to remained HAp splats. Copyright © 2014 Elsevier Ltd. All rights reserved.

The adhesion strength and residual stress of colloidal-sol gel derived β-Tricalcium-Phosphate/Fluoridated-Hydroxyapatite biphasic coatings

International Nuclear Information System (INIS)

Cheng Kui; Zhang, Sam; Weng Wenjian; Khor, Khiam Aik; Miao Shundong; Wang Yongsheng

2008-01-01

β-tricalcium phosphate (β-TCP) powders are embedded in a fluoridated hydroxyapatite (FHA) matrix to form β-TCP-FHA composites via colloidal-sol gel method. This composite layer is deposited on top of a FHA layer to form a β-TCP-FHA/FHA biphasic coating. The effect of the nanosized powder on the residual stress is characterized through the X-ray diffraction peak shift. The powder incorporation increases the residual stress, while a large amount of β-TCP (Ca powder /Ca sol ratio is higher than 1/2) results in less gel shrinkage that partially compensates the mismatch of thermal expansion coefficient and thus the residual stress. Despite the elevated residual stress as more powders are embedded, the coating adhesion strength remains virtually constant: around 430 mN-500 mN in scanning scratch test

Friction and wear properties of diamonds and diamond coatings

International Nuclear Information System (INIS)

Hayward, I.P.

1991-01-01

The recent development of chemical vapor deposition techniques for diamond growth enables bearings to be designed which exploit diamond's low friction and extreme resistance to wear. However, currently produced diamond coatings differ from natural diamond surfaces in that they are polycrystalline and faceted, and often contain appreciable amounts of non-diamond material (i.e. graphitic or amorphous carbon). Roughness, in particular, influences the friction and wear properties; rough coatings severely abrade softer materials, and can even wear natural diamond sliders. Nevertheless, the best available coatings exhibit friction coefficients as low as those of natural diamond and are highly resistant to wear. This paper reviews the tribological properties of natural diamond, and compares them with those of chemical vapor deposited diamond coatings. Emphasis is placed on the roles played by roughness and material transfer in controlling frictional behavior. (orig.)

TDHF simulation of the expansion of abraded nuclei

International Nuclear Information System (INIS)

Lacroix, D.; Chomaz, Ph.

1998-03-01

A recent interpretation of the caloric curve based on the expansion of the abraded spectator nuclear is re-analysed in the framework of the Time Dependent Hartree Fock (TDHF) evolution. It is shown that the TDHF dynamics can not be reduced to a single monopolar collective motion at moderate energy. The inclusion of other important collective degrees of freedom may lead to the dynamical creation of hollow structure. Then, low density regions could be locally reached after a long time by the creation of these exotic density profiles. The TDHF simulations do not confirm conclusions made when using an monopolar isentropic expansion. In particular the systematic of the minimum density reached during the expansion (the so-called turning points) appears to be different. (author)

Effect of Young's modulus evolution on residual stress measurement of thermal barrier coatings by X-ray diffraction

International Nuclear Information System (INIS)

Chen, Q.; Mao, W.G.; Zhou, Y.C.; Lu, C.

2010-01-01

Subjected to thermal cycling, the apparent Young's modulus of air plasma-sprayed (APS) 8 wt.% Y 2 O 3 -stabilized ZrO 2 (8YSZ) thermal barrier coatings (TBCs) was measured by nanoindentation. Owing to the effects of sintering and porous microstructure, the apparent Young's modulus follows a Weibull distribution and changes from 50 to 93 GPa with an increase of thermal cycling. The evolution of residual stresses in the top coating of an 8YSZ TBC system was determined by X-ray diffraction (XRD). The residual stresses derived from the XRD data are well consistent with that obtained by the Vickers indention. It is shown that the evolution of Young's modulus plays an important role in improving the measurement precision of residual stresses in TBCs by XRD.

Residual stress in thick low-pressure chemical-vapor deposited polycrystalline SiC coatings on Si substrates

Science.gov (United States)

Choi, D.; Shinavski, R. J.; Steffier, W. S.; Spearing, S. M.

2005-04-01

Residual stress in thick coatings of polycrystalline chemical-vapor deposited SiC on Si substrates is a key variable that must be controlled if SiC is to be used in microelectromechanical systems. Studies have been conducted to characterize the residual stress level as a function of deposition temperature, Si wafer and SiC coating thickness, and the ratios of methyltrichlorosilane to hydrogen and hydrogen chloride. Wafer curvature was used to monitor residual stress in combination with a laminated plate analysis. Compressive intrinsic (growth) stresses were measured with magnitudes in the range of 200-300MPa; however, these can be balanced with the tensile stress due to the thermal-expansion mismatch to leave near-zero stress at room temperature. The magnitude of the compressive intrinsic stress is consistent with previously reported values of surface stress in combination with the competition between grain-boundary energy and elastic strain energy.

Clinical Efficacy and Residue Depletion of 10% Enrofloxacin Enteric-Coated Granules in Pigs.

Science.gov (United States)

Lei, Zhixin; Liu, Qianying; Yang, Bing; Xiong, Jincheng; Li, Kun; Ahmed, Saeed; Hong, Liping; Chen, Pin; He, Qigai; Cao, Jiyue

2017-01-01

A new, more palatable formulation of 10% enrofloxacin enteric-coated granules was investigated to evaluate the pharmacokinetic effect in plasma, the residue elimination in tissues and the clinical efficacy against Actinobacillus pleuropneumonia (APP) and Mycoplasam suis (MS) in pigs. In this study, the enrofloxacin concentrations in plasma and tissues were detected using high-performance liquid chromatography with phosphate buffer (pH = 3) and acetonitrile. The pharmacokinetics and elimination of enrofloxacin enteric-coated granules were performed after oral administration at a single dose of 10 mg/kg body weight (bw) and 5 mg/kg twice per day for 5 consecutive days, respectively. The in vivo antibacterial efficacy and clinical effectiveness of enrofloxacin enteric-coated granules against APP and MS were assayed at 2.5, 5, 10 mg/kg, compared with tiamulin (8 mg/kg) based on establishment of APP and MS infection models. 56 APP strains were selected and tested for in vitro antibacterial activity of enrofloxacin enteric-coated granules. The main parameters of elimination half-life (t 1/2β ), T max , and area under the curve (AUC) were 14.99 ± 4.19, 3.99 ± 0.10, and 38.93 ± 1.52 μg h/ml, respectively, revealing that the enrofloxacin concentration remained high and with a sustainable distribution in plasma. Moreover, the analysis on the evaluation of enrofloxacin and ciprofloxacin in muscle, fat, liver and kidney showed that the recovery were more than 84% recovery in accordance with the veterinary drug residue guidelines of United States pharmacopeia, and the withdrawal periods were 4.28, 3.81, 4.84, and 3.51 days, respectively, suggesting that the withdrawal period was 5 d after oral administration of 5 mg/kg twice per day. The optimal dosage of enrofloxacin enteric-coated granules against APP and MS was 5 mg/kg, with over 90% efficacy, which was significantly different ( p enrofloxacin enteric-coated granules had significant potential for treating APP and MS

Residual stress evolution regularity in thermal barrier coatings under thermal shock loading

Directory of Open Access Journals (Sweden)

Ximin Chen

2014-01-01

Full Text Available Residual stress evolution regularity in thermal barrier ceramic coatings (TBCs under different cycles of thermal shock loading of 1100°C was investigated by the microscopic digital image correlation (DIC and micro-Raman spectroscopy, respectively. The obtained results showed that, as the cycle number of the thermal shock loading increases, the evolution of the residual stress undergoes three distinct stages: a sharp increase, a gradual change, and a reduction. The extension stress near the TBC surface is fast transformed to compressive one through just one thermal cycle. After different thermal shock cycles with peak temperature of 1100°C, phase transformation in TBC does not happen, whereas the generation, development, evolution of the thermally grown oxide (TGO layer and micro-cracks are the main reasons causing the evolution regularity of the residual stress.

Residual stress in coated low-Z films of TiC and TiN. Pt. 2

International Nuclear Information System (INIS)

Yoshizawa, I.; Kabeya, Z.; Kamada, K.

1984-01-01

The correlations of the residual stresses with microstructures of TiC and TiN films deposited onto various substrates were examined by means of observations of SEM micrographs, X-ray back-reflected Debye rangs and diffraction line profile of X-ray spectrometer chart. It was found that specimens with lower residual stress generally show sharp line profile and good separation between Ksub(α1) and Ksub(α2) diffraction peaks in both TiN and TiC films, indicating better crystalline perfection. PVD coated TiC films on Mo and Inconel substrates show poor separation of Ksub(α1) and Ksub(α2) peaks, namely due to higher residual stresses in comparison with those of CVD coated TiN and TiC films on Mo or Inconel substrate. In CVD TiC/Pocographite system, with film thickness ranging from 10 to 100 μm, the grain size increase with increasing the thickness, except 100 μm thick specimen which has the smallest grain size in this group. However, the sharpness of diffraction profile is best in 20 μm thick film, and worst in 100 μm thick film. This is in good correlation with the amount of residual stress. (orig.)

The use of neutron diffraction for the determination of the in-depth residual stresses profile in weld coatings

International Nuclear Information System (INIS)

Marques, Maria Jose; Batista, A.C.; Nobre, J.P.; Loureiro, Altino; Kornmeier, Joana R.

2013-01-01

The neutron diffraction is a non-destructive technique, particularly suitable for the analysis of residual stress fields in welds. The technique is used in this article to study ferritic samples, coated by submerged arc welding using stainless steel filler metals. This procedure is often used for manufacturing process equipment for chemical and nuclear industries, for ease of implementation and economic reasons. The main disadvantage of that processes is the cracking phenomenon that often occurs at the interface between the base material and coatings, which can be minimized by performing post-weld stress relief heat treatments. The samples analyzed in this study were made of carbon steel plates, coated by submerged arc welding two types of stainless steel filler metals. For the first layer was used one EN 12 072 - S 2 U 23 12 electrode, while for the second and third layers were used an EN 12 072 - 19 12 3 S L electrode. After cladding, the samples were submitted to a post-weld heat treatment for 1 hour at 620 deg C. The residual stress profiles obtained by neutron diffraction evidence the relaxation of residual stress given by the heat treatment. (author)

Clinical Efficacy and Residue Depletion of 10% Enrofloxacin Enteric-Coated Granules in Pigs

Directory of Open Access Journals (Sweden)

Zhixin Lei

2017-05-01

Full Text Available A new, more palatable formulation of 10% enrofloxacin enteric-coated granules was investigated to evaluate the pharmacokinetic effect in plasma, the residue elimination in tissues and the clinical efficacy against Actinobacillus pleuropneumonia (APP and Mycoplasam suis (MS in pigs. In this study, the enrofloxacin concentrations in plasma and tissues were detected using high-performance liquid chromatography with phosphate buffer (pH = 3 and acetonitrile. The pharmacokinetics and elimination of enrofloxacin enteric-coated granules were performed after oral administration at a single dose of 10 mg/kg body weight (bw and 5 mg/kg twice per day for 5 consecutive days, respectively. The in vivo antibacterial efficacy and clinical effectiveness of enrofloxacin enteric-coated granules against APP and MS were assayed at 2.5, 5, 10 mg/kg, compared with tiamulin (8 mg/kg based on establishment of APP and MS infection models. 56 APP strains were selected and tested for in vitro antibacterial activity of enrofloxacin enteric-coated granules. The main parameters of elimination half-life (t1/2β, Tmax, and area under the curve (AUC were 14.99 ± 4.19, 3.99 ± 0.10, and 38.93 ± 1.52 μg h/ml, respectively, revealing that the enrofloxacin concentration remained high and with a sustainable distribution in plasma. Moreover, the analysis on the evaluation of enrofloxacin and ciprofloxacin in muscle, fat, liver and kidney showed that the recovery were more than 84% recovery in accordance with the veterinary drug residue guidelines of United States pharmacopeia, and the withdrawal periods were 4.28, 3.81, 4.84, and 3.51 days, respectively, suggesting that the withdrawal period was 5 d after oral administration of 5 mg/kg twice per day. The optimal dosage of enrofloxacin enteric-coated granules against APP and MS was 5 mg/kg, with over 90% efficacy, which was significantly different (p < 0.05 to the 2.5 mg/kg group, but not to the 10 mg/kg group or the positive

Determination of elastic modulus and residual stress of plasma-sprayed tungsten coating on steel substrate

Science.gov (United States)

You, J. H.; Höschen, T.; Lindig, S.

2006-01-01

Plasma-sprayed tungsten, which is a candidate material for the first wall armour, shows a porous, heterogeneous microstructure. Due to its characteristic morphology, the properties are significantly different from those of its dense bulk material. Measurements of the elastic modulus of this coating have not been reported in the literature. In this work Young's modulus of highly porous plasma-sprayed tungsten coatings deposited on steel (F82H) substrates was measured. For the fabrication of the coating system the vacuum plasma-spray process was applied. Measurements were performed by means of three-point and four-point bending tests. The obtained modulus values ranged from 53 to 57 GPa. These values could be confirmed by the test result of a detached coating strip, which was 54 GPa. The applied methods produced consistent results regardless of testing configurations and specimen sizes. The errors were less than 1%. Residual stress of the coating was also estimated.

Determination of elastic modulus and residual stress of plasma-sprayed tungsten coating on steel substrate

International Nuclear Information System (INIS)

You, J.H.; Hoeschen, T.; Lindig, S.

2006-01-01

Plasma-sprayed tungsten, which is a candidate material for the first wall armour, shows a porous, heterogeneous microstructure. Due to its characteristic morphology, the properties are significantly different from those of its dense bulk material. Measurements of the elastic modulus of this coating have not been reported in the literature. In this work Young's modulus of highly porous plasma-sprayed tungsten coatings deposited on steel (F82H) substrates was measured. For the fabrication of the coating system the vacuum plasma-spray process was applied. Measurements were performed by means of three-point and four-point bending tests. The obtained modulus values ranged from 53 to 57 GPa. These values could be confirmed by the test result of a detached coating strip, which was 54 GPa. The applied methods produced consistent results regardless of testing configurations and specimen sizes. The errors were less than 1%. Residual stress of the coating was also estimated

Comparison of Some Mechanical and Physical Methods for Measurement of Residual Stresses in Brush-Plated Nickel Hardened Gold and Silver Coatings

Directory of Open Access Journals (Sweden)

Harri LILLE

2016-05-01

Full Text Available Hard gold and silver are applied in coating owing to their high hardness, good wear and corrosion resistance for engineering application (e.g. on generators slip rings, sliding contacts and small machine parts and are typically plated on copper (mostly, brass and bronze. The studied nickel-hardened gold and silver coatings were brush plated on open thin-walled copper ring substrates. Residual stresses in the coatings were calculated from the curvature changes of the substrates. Biaxial intrinsic residual stresses were also determined by nanoindentation testing and by the X-ray technique. The values of the residual stresses represented tensile stresses and when determined by the techniques used they were comparable within a maximum limit of measurement uncertainty. These stresses relax; the dependence of relaxation time was approximated by a linear-fractional function.DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7439

Shear bond strength between an indirect composite layering material and feldspathic porcelain-coated zirconia ceramics.

Science.gov (United States)

Fushiki, Ryosuke; Komine, Futoshi; Blatz, Markus B; Koizuka, Mai; Taguchi, Kohei; Matsumura, Hideo

2012-10-01

This study aims to evaluate the effect of both feldspathic porcelain coating of zirconia frameworks and priming agents on shear bond strength between an indirect composite material and zirconia frameworks. A total of 462 airborne-particle-abraded zirconia disks were divided into three groups: untreated disks (ZR-AB), airborne-particle-abraded zirconia disks coated with feldspathic porcelain, (ZR-PO-AB), and hydrofluoric acid-etched zirconia disks coated with feldspathic porcelain (ZR-PO-HF). Indirect composite (Estenia C&B) was bonded to zirconia specimens with no (CON) or one of four priming agents--Clearfil Photo Bond (CPB), Clearfil Photo Bond with Clearfil Porcelain Bond Activator (CPB + activator), Estenia Opaque primer, or Porcelain Liner M Liquid B (PLB)--with or without an opaque material (Estenia C&B Opaque). All specimens were tested for shear bond strength before and after 20,000 thermocycles. The Steel-Dwass test and Mann-Whitney U test were used to compare shear bond strength. In ZR-AB specimens, the initial bond strength of the CPB and CPB + Activator groups was significantly higher as compared with the other three groups (P material, bond strength was significantly lower in ZR-AB specimens than in ZR-PO-AB and ZR-PO-HF specimens (P composite to zirconia independent of surface treatment. The use of a silane coupling agent and opaque material yields durable bond strength between the indirect composite and feldspathic-porcelain-coated zirconia. The results of the present study suggest that feldspathic porcelain coating of zirconia frameworks is an effective method to obtain clinically acceptable bond strengths of a layering indirect composite material to a zirconia framework.

Thermal input control and enhancement for laser based residual stress measurements using liquid temperature indicating coatings

Science.gov (United States)

Pechersky, Martin J.

1999-01-01

An improved method for measuring residual stress in a material comprising the steps of applying a spot of temperature indicating coating to the surface to be studied, establishing a speckle pattern surrounds the spot of coating with a first laser then heating the spot of coating with a far infrared laser until the surface plastically deforms. Comparing the speckle patterns before and after deformation by subtracting one pattern from the other will produce a fringe pattern that serves as a visual and quantitative indication of the degree to which the plasticized surface responded to the stress during heating and enables calculation of the stress.

Implementation and Development of the Incremental Hole Drilling Method for the Measurement of Residual Stress in Thermal Spray Coatings

Science.gov (United States)

Valente, T.; Bartuli, C.; Sebastiani, M.; Loreto, A.

2005-12-01

The experimental measurement of residual stresses originating within thick coatings deposited by thermal spray on solid substrates plays a role of fundamental relevance in the preliminary stages of coating design and process parameters optimization. The hole-drilling method is a versatile and widely used technique for the experimental determination of residual stress in the most superficial layers of a solid body. The consolidated procedure, however, can only be implemented for metallic bulk materials or for homogeneous, linear elastic, and isotropic materials. The main objective of the present investigation was to adapt the experimental method to the measurement of stress fields built up in ceramic coatings/metallic bonding layers structures manufactured by plasma spray deposition. A finite element calculation procedure was implemented to identify the calibration coefficients necessary to take into account the elastic modulus discontinuities that characterize the layered structure through its thickness. Experimental adjustments were then proposed to overcome problems related to the low thermal conductivity of the coatings. The number of calculation steps and experimental drilling steps were finally optimized.

Technology and function of grooved abraders in the early Neolithic of northwestern Europe

Directory of Open Access Journals (Sweden)

Caroline Hamon

2016-10-01

Full Text Available Found sporadically in late Palaeolithic and Mesolithic contexts, grooved abraders are among the most common tools found in Linear Pottery and Villeneuve-Saint-Germain settlements in north-western Europe (5,100-4,700 BCE. This paper presents an overview of the technical and functional characteristics of these tools in early Neolithic domestic contexts. Despite different blank morphologies and sizes, these tools tend to be relatively small in size and are generally not shaped. They are characterized by the use of a very specific raw material: low cohesive and generally ferruginous sandstones, chosen because their abrasiveness is enhanced through use. A classification of the different types of grooves is proposed, based on their shape, depth, section and localization. These characteristics are combined with use-wear analysis in order to propose a number of functional interpretations. Far from the widespread hypothesis that these tools functioned as shaft straighteners, we argue on the basis of the use-wear analysis and archaeological associations of items that these tools were primarily involved in the manufacture of bone and lithic tools, as well as of schist and limestone personal ornaments. They are evidence of the generalization and diversification of polishing and abrading techniques in the technical system of the first Neolithic populations. As such, they contribute to defining a whole new technical paradigm and are an essential element in any definition of the Neolithic.

Residual stress, mechanical and microstructure properties of multilayer Mo{sub 2}N/CrN coating produced by R.F Magnetron discharge

Energy Technology Data Exchange (ETDEWEB)

Bouaouina, B., E-mail: b.bouaouina@gmail.com [Department of physic, research unite UR-MPE, Boumerdes University 35000 (Algeria); Besnard, A. [Arts et Metiers ParisTech—LaBoMaP, 71250 Cluny (France); Abaidia, S.E. [Department of physic, research unite UR-MPE, Boumerdes University 35000 (Algeria); Haid, F. [CDTA, Plasma discharges Group, Baba hassen, Algers (Algeria)

2017-02-15

Highlights: • Depositing of crystallized molybdenum nitride and chromium nitride multilayer at room temperature. • Correlation between stress measurement and the shift of the XRD diffraction peak (1 1 1) of Mo{sub 2}N. • Studied the effect of the bi-layer thickness on the mechanical properties. - Abstract: We have investigated the effect of the period thickness of the multilayer Mo{sub 2}N/CrN deposited on Si substrate produced by reactive magnetron sputtering. Mo{sub 2}N presents a face centered cubic structure and CrN an orthorhombic one. The residual stress of the coatings was determined by the measurement of the substrate curvature. The microstructure of the multilayer was investigated from the X-ray diffraction and scanning electron microscopy (cross section images). The residual stresses resulting from the deposition of the different bi-layer thickness were measured and correlated to the structural properties of the coating as well as the nanoindentation analysis of the coating. The stresses are compressive and tensile for the individual Mo{sub 2}N and CrN layer respectively. The result shows that an increase of the multilayer coatings Mo{sub 2}N/CrN thicknesses induce an increase of the hardness and the elastic modulus, in the other hand the tensile stress increases. The shift of the XRD diffraction peak (1 1 1) of Mo{sub 2}N at high angle which means the reduction of the residual stress is in good agreement with the residual stresses measurements.

Through-thickness Residual Stress Measurement by Neutron Diffraction in Cu+W Plasma Spray Coatings

Czech Academy of Sciences Publication Activity Database

Luzin, V.; Matějíček, Jiří; Gnäupel-Herold, T.

2010-01-01

Roč. 652, č. 652 (2010), s. 50-56 ISSN 1662-9752. [International Conference on Mechanical Stress Evaluation by Neutrons and Synchrotron Radiation/5th./. Mito, 10.11.2009-12.11.2009] R&D Projects: GA MŠk ME 901 Institutional research plan: CEZ:AV0Z20430508 Keywords : fusion materials * plasma sprayed coatings * residual stress * neutron diffraction Subject RIV: JG - Metallurgy http://www.scientific.net/MSF.652.50

Effect of heat treatment on residual stress and wear behaviors of the TiNi/Ti2Ni based laser cladding composite coatings

Science.gov (United States)

Tao, Yang-Feng; Li, Jun; Lv, Ying-Hao; Hu, Lie-Feng

2017-12-01

The TiNi/Ti2Ni based composite coatings reinforced by TiC and TiB2 were prepared on Ti6Al4V at different circumstance temperatures (25 °C, 400 °C, 600 °C, and 800 °C) by laser cladding, then were preserved for 3 h. Macromorphologies and microstructures of the coatings were examined through an optical microscope (OM), an X-ray diffractometer (XRD), a scanning electron microscope (SEM), and an energy dispersive spectrometer (EDS). Residual stresses along the depth direction of the coatings were measured by the nanoindentation method, and wear behaviors of the coatings were also investigated using an ultra-functional wear testing machine. Results showed that the coatings were mainly composed of TiNi/Ti2Ni as the matrix and TiC/TiB2 as the reinforcement. A small amount of Cr2Ti was formed in the coatings prepared at 400 °C and 600 °C. Besides that, Ti3Al was also observed in the coating prepared at 800 °C. The tensile stress existed in the coatings prepared at 25 °C, 400 °C and 600 °C when the coating prepared at 800 °C was regarded as the stress-free reference. The average residual stress in the surface of coating prepared at 25 °C reached the largest value of about 2.79 GPa and presented a decreasing tendency with increasing the circumstance temperature (1.03 GPa at 400 °C, 0.52 GPa at 600 °C, and 0 GPa at 800 °C). It revealed that the rise in circumstance temperature contributed to the reduction in cracking susceptibility in the laser cladding coating. However, the wear volumes of the coatings were increased with increasing the circumstance temperature (0.1912 mm3 at 25 °C, 0.2828 mm3 at 400 °C, 0.3732 mm3 at 600 °C, and 0.6073 mm3 at 800 °C) due to the weakening in strain-hardening effect and the reduction in reinforcement density. The wear mechanism of the coatings was transformed from the single brittle-debonding into the combination of micro-cutting and brittle-debonding when the circumstance temperature was changed from room temperature to

Production of reactive oxygen species from abraded silicates. Implications for the reactivity of the Martian soil

Science.gov (United States)

Bak, Ebbe N.; Zafirov, Kaloyan; Merrison, Jonathan P.; Jensen, Svend J. Knak; Nørnberg, Per; Gunnlaugsson, Haraldur P.; Finster, Kai

2017-09-01

The results of the Labeled Release and the Gas Exchange experiments conducted on Mars by the Viking Landers show that compounds in the Martian soil can cause oxidation of organics and a release of oxygen in the presence of water. Several sources have been proposed for the oxidizing compounds, but none has been validated in situ and the cause of the observed oxidation has not been resolved. In this study, laboratory simulations of saltation were conducted to examine if and under which conditions wind abrasion of silicates, a process that is common on the Martian surface, can give rise to oxidants in the form of hydrogen peroxide (H2O2) and hydroxyl radicals (ṡOH). We found that silicate samples abraded in simulated Martian atmospheres gave rise to a significant production of H2O2 and ṡOH upon contact with water. Our experiments demonstrated that abraded silicates could lead to a production of H2O2 facilitated by atmospheric O2 and inhibited by carbon dioxide. Furthermore, during simulated saltation the silicate particles became triboelectrically charged and at pressures similar to the Martian surface pressure we observed glow discharges. Electrical discharges can cause dissociation of CO2 and through subsequent reactions lead to a production of H2O2. These results indicate that the reactions linked to electrical discharges are the dominant source of H2O2 during saltation of silicates in a simulated Martian atmosphere, given the low pressure and the relatively high concentration of CO2. Our experiments provide evidence that wind driven abrasion could enhance the reactivity of the Martian soil and thereby could have contributed to the oxidation of organic compounds and the O2 release observed in the Labeled Release and the Gas Exchange experiments. Furthermore, the release of H2O2 and ṡOH from abraded silicates could have a negative effect on the persistence of organic compounds in the Martian soil and the habitability of the Martian surface.

Simulation and analysis of the residual stresses in functionally graded Al2O3 coatings on CLAM steel

International Nuclear Information System (INIS)

Yan Zilin; Huang Qunying; Song Yong; Guo Zhihui; Wu Yican

2008-01-01

Alumina coatings on CLAM steel substrate are proposed to serve as tritium, corrosion and electric insulation barriers in the design of Dual Functional Lithium Lead Test Blanket Module (DFLL-TBM) in China in the frame of ITER. In order to avoid the crack failure due to thermal expansion mismatch of the coating and the substrate, the functionally graded materials (FGM) concept was adopted. In this paper, the residual thermal stresses in the coatings were calculated with the commercial software ANSYS. It is recommended that the compositional factor, numbers of the gradient interlayers and the thickness of the FGM zone are p=0.8, N=8, H=0.6 mm, respectively, according to the simulation results. These results could be helpful and theoretical guidance to the preparation and optimization of the coatings in the future. (authors)

Sea water Corrosion of Nickel based Plasma Spray Coating

Science.gov (United States)

Parida, M.; Nanda, S. P.; Bhuyan, S. K.; Mishra, S. C.

2018-03-01

Different types of erosion resistant coatings are applied/deposited on aero components, depending on the operating/working temperatures. Nickel based coating are applied on the air craft (compressor) components, which can sustain up to working temperature of 650°C. In the present investigation, to improve the compatibility between substrate (i.e. the machine component) and the top coat, application of bond coat is there. The application of Nickel based coating by thermal plasma spray technique has proven to be a satisfactory means of producing acceptable sealing surface with excellent abradability. Before the corrosion study, coated sample is subjected to hardness, thickness and porosity testing. Hence the result is being evaluated. The corrosion behavior of coating was studied by sea water immersion with a time period of 16 weeks. It is observed that, up to 9 weeks increase in weight of coating occurs in a sharp trend and then takes a decreasing trend. The weight gain of the samples has varied from 37.23% (with one week immersion in sea water) to a maximum of about 64.36% for six weeks immersion. Coating morphology and composition analysis of the coatings are studied using SEM and EDS. This behavior shows adsorption/deposition of the foreign particles with polygonal shape on the coating surface by sea water interaction. Foreign particles with polygonal shape deposited on the coating and with increase in immersion/treatment time, washing out of the deposited materials starts, which reflects the decreasing trend of weight gain of the specimen.

Flow accelerated organic coating degradation

Science.gov (United States)

Zhou, Qixin

Applying organic coatings is a common and the most cost effective way to protect metallic objects and structures from corrosion. Water entry into coating-metal interface is usually the main cause for the deterioration of organic coatings, which leads to coating delamination and underfilm corrosion. Recently, flowing fluids over sample surface have received attention due to their capability to accelerate material degradation. A plethora of works has focused on the flow induced metal corrosion, while few studies have investigated the flow accelerated organic coating degradation. Flowing fluids above coating surface affect corrosion by enhancing the water transport and abrading the surface due to fluid shear. Hence, it is of great importance to understand the influence of flowing fluids on the degradation of corrosion protective organic coatings. In this study, a pigmented marine coating and several clear coatings were exposed to the laminar flow and stationary immersion. The laminar flow was pressure driven and confined in a flow channel. A 3.5 wt% sodium chloride solution and pure water was employed as the working fluid with a variety of flow rates. The corrosion protective properties of organic coatings were monitored inline by Electrochemical Impedance Spectroscopy (EIS) measurement. Equivalent circuit models were employed to interpret the EIS spectra. The time evolution of coating resistance and capacitance obtained from the model was studied to demonstrate the coating degradation. Thickness, gloss, and other topography characterizations were conducted to facilitate the assessment of the corrosion. The working fluids were characterized by Fourier Transform Infrared Spectrometer (FTIR) and conductivity measurement. The influence of flow rate, fluid shear, fluid composition, and other effects in the coating degradation were investigated. We conclude that flowing fluid on the coating surface accelerates the transport of water, oxygen, and ions into the coating, as

X-ray diffraction of residual stresses in boron nitride coated on steel substrate

International Nuclear Information System (INIS)

Hamzah, E.; Ramdan, R.D.; Venkatesh, V.C.; Hamid, N.H.B.

2002-01-01

Cubic boron nitride (cBN) is a promising coating material for cutting tools especially for applications that have contact with ferrous metals. This is because of its extreme hardness, chemical stability at high temperature and inertness with ferrous metals. However applications of cBN as coating material has not been used extensively due to the poor adhesion between cBN and its substrate. High stress level in the film is considered to be the main factor for the delamination of cBN films after deposition. Thus the present research concentrates on residual stress analysis of cBN films by x-ray diffraction method. Fourier transform infra-red (FTIR) spectroscopy analysis was also performed on the samples to study the structure of the deposited films. Based on the present experimental results and previous literature study, a new theoretical model for cBN film growth was proposed. (Author)

Investigations on antibody binding to a micro-cantilever coated with a BAM pesticide residue

Directory of Open Access Journals (Sweden)

Aamand Jens

2011-01-01

Full Text Available Abstract The attachment of an antibody to an antigen-coated cantilever has been investigated by repeated experiments, using a cantilever-based detection system by Cantion A/S. The stress induced by the binding of a pesticide residue BAM (2,6 dichlorobenzamide immobilized on a cantilever surface to anti-BAM antibody is measured using the CantiLab4© system from Cantion A/S with four gold-coated cantilevers and piezo resistive readout. The detection mechanism is in principle label-free, but fluorescent-marked antibodies have been used to subsequently verify the binding on the cantilever surface. The bending and increase in mass of each cantilever has also been investigated using a light interferometer and a Doppler Vibrometer. The system has been analyzed during repeated measurements to investigate whether the CantiLab4© system is a suited platform for a pesticide assay system.

Optical tools for high-throughput screening of abrasion resistance of combinatorial libraries of organic coatings

Science.gov (United States)

Potyrailo, Radislav A.; Chisholm, Bret J.; Olson, Daniel R.; Brennan, Michael J.; Molaison, Chris A.

2002-02-01

Design, validation, and implementation of an optical spectroscopic system for high-throughput analysis of combinatorially developed protective organic coatings are reported. Our approach replaces labor-intensive coating evaluation steps with an automated system that rapidly analyzes 8x6 arrays of coating elements that are deposited on a plastic substrate. Each coating element of the library is 10 mm in diameter and 2 to 5 micrometers thick. Performance of coatings is evaluated with respect to their resistance to wear abrasion because this parameter is one of the primary considerations in end-use applications. Upon testing, the organic coatings undergo changes that are impossible to quantitatively predict using existing knowledge. Coatings are abraded using industry-accepted abrasion test methods at single-or multiple-abrasion conditions, followed by high- throughput analysis of abrasion-induced light scatter. The developed automated system is optimized for the analysis of diffusively scattered light that corresponds to 0 to 30% haze. System precision of 0.1 to 2.5% relative standard deviation provides capability for the reliable ranking of coatings performance. While the system was implemented for high-throughput screening of combinatorially developed organic protective coatings for automotive applications, it can be applied to a variety of other applications where materials ranking can be achieved using optical spectroscopic tools.

A synchrotron X-ray diffraction deconvolution method for the measurement of residual stress in thermal barrier coatings as a function of depth.

Science.gov (United States)

Li, C; Jacques, S D M; Chen, Y; Daisenberger, D; Xiao, P; Markocsan, N; Nylen, P; Cernik, R J

2016-12-01

The average residual stress distribution as a function of depth in an air plasma-sprayed yttria stabilized zirconia top coat used in thermal barrier coating (TBC) systems was measured using synchrotron radiation X-ray diffraction in reflection geometry on station I15 at Diamond Light Source, UK, employing a series of incidence angles. The stress values were calculated from data deconvoluted from diffraction patterns collected at increasing depths. The stress was found to be compressive through the thickness of the TBC and a fluctuation in the trend of the stress profile was indicated in some samples. Typically this fluctuation was observed to increase from the surface to the middle of the coating, decrease a little and then increase again towards the interface. The stress at the interface region was observed to be around 300 MPa, which agrees well with the reported values. The trend of the observed residual stress was found to be related to the crack distribution in the samples, in particular a large crack propagating from the middle of the coating. The method shows promise for the development of a nondestructive test for as-manufactured samples.

Evaluation of the interfacial shear strength and residual stress of TiAlN coating on ZIRLO™ fuel cladding using a modified shear-lag model approach

Energy Technology Data Exchange (ETDEWEB)

Liu, Y., E-mail: troy.liu@manchester.ac.uk [Materials Performance Centre, School of Materials, The University of Manchester, M13 9PL (United Kingdom); Bhamji, I., E-mail: imran.bhamji@manchester.ac.uk [Materials Performance Centre, School of Materials, The University of Manchester, M13 9PL (United Kingdom); Withers, P.J., E-mail: p.j.withers@manchester.ac.uk [Materials Performance Centre, School of Materials, The University of Manchester, M13 9PL (United Kingdom); Wolfe, D.E., E-mail: dew125@arl.psu.edu [The Pennsylvania State University, University Park, State College, PA 16801 (United States); Motta, A.T., E-mail: atmnuc@engr.psu.edu [The Pennsylvania State University, University Park, State College, PA 16801 (United States); Preuss, M., E-mail: michael.preuss@manchester.ac.uk [Materials Performance Centre, School of Materials, The University of Manchester, M13 9PL (United Kingdom)

2015-11-15

This paper investigates the residual stresses and interfacial shear strength of a TiAlN coating on Zr–Nb–Sn–Fe alloy (ZIRLO™) substrate designed to improve corrosion resistance of fuel cladding used in water-cooled nuclear reactors, both during normal and exceptional conditions, e.g. a loss of coolant event (LOCA). The distribution and maximum value of the interfacial shear strength has been estimated using a modified shear-lag model. The parameters critical to this analysis were determined experimentally. From these input parameters the interfacial shear strength between the TiAlN coating and ZIRLO™ substrate was inferred to be around 120 MPa. It is worth noting that the apparent strength of the coating is high (∼3.4 GPa). However, this is predominantly due to the large compressive residuals stress (3 GPa in compression), which must be overcome for the coating to fail in tension, which happens at a load just 150 MPa in excess of this.

Modeling and experimental study of residual stresses in NOREM hardfacing coatings used in valve parts

International Nuclear Information System (INIS)

Beaurin, G.

2012-01-01

Hardfacing coatings are widely used on the surfaces of parts subjected to drastic loadings. Norem02 alloy, Fe-based, is used in PWR nuclear power plants on valves seating surfaces. Its microstructure consists of a dendritic austenite structure with ferrite islets and carbides. This work tends to demonstrate that for this alloy, metallurgical evolution during the welding process has very little influence on mechanical properties. Tensile behavior was characterized and completed by dilatometry tests in welding process temperature range until 1000 Celsius degrees, in order to identify an elastoplastic model with non linear kinematic hardening rule. Temperature, displacements, distortions and residual stresses were measured during the PTAW (Plasma Transferred Arc Welding) process and used to identify an equivalent thermal loading by solving an inverse problem. Finally, the numerical simulation of the whole process using the EDF FEM software Code-Aster is presented. Predicted temperatures are consistent with experimental ones. In the same way, predicted displacements, residual distortions and residual stresses at the end of the cooling phase are close to experimental measures, validating the modeling strategy presented in this work. (author)

X-ray residual stress measurement and its variation during plane bending fatigue and sliding wear processes in TiC, TiN, TiB2 and Al2O3 coated carbon steels

International Nuclear Information System (INIS)

Endoh, Takashi; Idemitsu, Kohji; Kawakami, Mamoru

1993-01-01

The development of ceramic coating to metals was stimulated by the need for high temperature, wear and corrosion resistant materials. Recently TiC, TiN, TiB 2 and Al 2 O 3 are used as ceramic coating materials. In the present study, the X-ray method was successfully applied to measure the residual stress distribution in their ceramics coated steels. The X-ray elastic constants were determined and compared with the mechanically measured values. And plane bending and sliding wear tests were carried out. The X-ray method was successfully applied to measure the residual stress changes during fatigue and wear processes. The relationship between the change of residual stress and damage accumulation was investigated. (author)

A flexible method for residual stress measurement of spray coated layers by laser made hole drilling and SLM based beam steering

Science.gov (United States)

Osten, W.; Pedrini, G.; Weidmann, P.; Gadow, R.

2015-08-01

A minimum invasive but high resolution method for residual stress analysis of ceramic coatings made by thermal spraycoating using a pulsed laser for flexible hole drilling is described. The residual stresses are retrieved by applying the measured surface data for a model-based reconstruction procedure. While the 3D deformations and the profile of the machined area are measured with digital holography, the residual stresses are calculated by FE analysis. To improve the sensitivity of the method, a SLM is applied to control the distribution and the shape of the holes. The paper presents the complete measurement and reconstruction procedure and discusses the advantages and challenges of the new technology.

Nanocryl Coating of PMMA Complete Denture Base Materials to Prevent Scratching.

Science.gov (United States)

Fathi, Hawa M; Benonn, Hajer A; Johnson, Anthony

2017-09-01

The surface of polymethylmethacrylate (PMMA) is vulnerable to indentation by hard objects that may contribute to abrade the material surface and subject it to wear. This phenomenon promotes an increase in the surface roughness leading to microbial colonisation which can endanger the general health of wearers and damage the intra-oral prosthesis. The aim of this study is to investigate the effect of three different nanocryl coating agents (Easy Glaze, G-Coat Plus and Formulation XP) on surface roughness and thickness of PMMA material after a simulating cleaning process utilizing an electric toothbrush and three different dentifrices (pastes and immersion). Acrylic uncoated discs were used as a control group. The results showed that the G-Coat Plus coating agent had less changes in the surface roughness and thickness layer whereas the immersion cleaner revealed less abrasion effect compared with the paste cleaners which could be considered the most suitable cleaner to provide lower abrasivenes and good removal of organic debris. However, using nanofilled sealants did not demonstrate significant improvement in reducing surface roughness p ⟩ 0.05. Nevertheless, it could provide some protection against wearing to the acrylic resin surface during tooth brushing and may provide better resistance to microbial colonisation. Copyright© 2017 Dennis Barber Ltd.

The oxidation of titanium nitride- and silicon nitride-coated stainless steel in carbon dioxide environments

International Nuclear Information System (INIS)

Mitchell, D.R.G.; Stott, F.H.

1992-01-01

A study has been undertaken into the effects of thin titanium nitride and silicon nitride coatings, deposited by physical vapour deposition and chemical vapour deposition processes, on the oxidation resistance of 321 stainless steel in a simulated advanced gas-cooled reactor carbon dioxide environment for long periods at 550 o C and 700 o C under thermal-cycling conditions. The uncoated steel contains sufficient chromium to develop a slow-growing chromium-rich oxide layer at these temperatures, particularly if the surfaces have been machine-abraded. Failure of this layer in service allows formation of less protective iron oxide-rich scales. The presence of a thin (3-4 μm) titanium nitride coating is not very effective in increasing the oxidation resistance since the ensuing titanium oxide scale is not a good barrier to diffusion. Even at 550 o C, iron oxide-rich nodules are able to develop following relatively rapid oxidation and breakdown of the coating. At 700 o C, the coated specimens oxidize at relatively similar rates to the uncoated steel. A thin silicon nitride coating gives improved oxidation resistance, with both the coating and its slow-growing oxide being relatively electrically insulating. The particular silicon nitride coating studied here was susceptible to spallation on thermal cycling, due to an inherently weak coating/substrate interface. (Author)

Sustainable and long-time 'rejuvenation' of biomimetic water-repellent silica coating on polyester fabrics induced by rough mechanical abrasion.

Science.gov (United States)

Rosu, Cornelia; Lin, Haisheng; Jiang, Lu; Breedveld, Victor; Hess, Dennis W

2018-04-15

The economical use of water-repellent coatings on polymeric materials in commercial and industrial applications is limited by their mechanical wear robustness and long-term durability. In this study, we demonstrate that polyethylene terephthalate (PET) fabric modified with inorganic, methyltrimethoxysilane (MTMS)-based coatings shows excellent resistance against various types of wear damage, thereby mimicking superhydrophobic biological materials. These features were facilitated by the rational design of coating processing that also enabled tunable hierarchical surface structure. A series of custom and standard testing protocols revealed that coating-to-substrate adhesion was remarkably high, as was the resistance to various mechanical abradents. The most intriguing characteristic observed during aging and abrasion cycles was the enhancement in non-wettability or 'rejuvenation' reflected by water droplet roll-off behavior, a characteristic of self-cleaning materials. Water-repellent properties of coated polyester were also enhanced by prolonged thermal annealing and were maintained after custom laundry. The developed technology offers opportunities to design low cost, durable and functional textiles for both indoor and outdoor applications. Copyright © 2018 Elsevier Inc. All rights reserved.

Active thermography and post-processing image enhancement for recovering of abraded and paint-covered alphanumeric identification marks

Science.gov (United States)

Montanini, R.; Quattrocchi, A.; Piccolo, S. A.

2016-09-01

Alphanumeric marking is a common technique employed in industrial applications for identification of products. However, the realised mark can undergo deterioration, either by extensive use or voluntary deletion (e.g. removal of identification numbers of weapons or vehicles). For recovery of the lost data many destructive or non-destructive techniques have been endeavoured so far, which however present several restrictions. In this paper, active infrared thermography has been exploited for the first time in order to assess its effectiveness in restoring paint covered and abraded labels made by means of different manufacturing processes (laser, dot peen, impact, cold press and scribe). Optical excitation of the target surface has been achieved using pulse (PT), lock-in (LT) and step heating (SHT) thermography. Raw infrared images were analysed with a dedicated image processing software originally developed in Matlab™, exploiting several methods, which include thermographic signal reconstruction (TSR), guided filtering (GF), block guided filtering (BGF) and logarithmic transformation (LN). Proper image processing of the raw infrared images resulted in superior contrast and enhanced readability. In particular, for deeply abraded marks, good outcomes have been obtained by application of logarithmic transformation to raw PT images and block guided filtering to raw phase LT images. With PT and LT it was relatively easy to recover labels covered by paint, with the latter one providing better thermal contrast for all the examined targets. Step heating thermography never led to adequate label identification instead.

On the Electrodeposition of Ca-P Coatings on Nitinol Alloy: A Comparison Between Different Surface Modification Methods

Science.gov (United States)

Etminanfar, M. R.; Khalil-Allafi, J.

2016-02-01

In this study, a combination of surface modification process and the electrochemical deposition of Ca-P coatings was used for the modification of the Nitinol shape memory alloy. DSC, SEM, GIB-XRD, FT-Raman, XPS, and FTIR measurements were performed for the characterization of the samples. Results indicated that chemical etching and boiling of the samples in distilled water formed TiO film on the surface. After the chemical modification, subsequent aging of the sample, at 470 °C for 30 min, converted the oxide film to a stable structure of titanium dioxide. In that case, the treated substrate indicated a superelastic behavior. At the same electrochemical condition, the treated substrate revealed more stable and uniform Ca-P coatings in comparison with the abraded Nitinol substrate. This difference was attributed to the presence of hydroxyl groups on the titanium dioxide surface. Also, after soaking the sample in SBF, the needle-like coating on the treated substrate was completely covered with the hydroxyapatite phase which shows a good bioactivity of the coating.

Biofilm development by blastospores and hyphae of Candida albicans on abraded denture acrylic resin surfaces.

Science.gov (United States)

Jackson, Sarah; Coulthwaite, Lisa; Loewy, Zvi; Scallan, Anthony; Verran, Joanna

2014-10-01

Candida albicans is a known etiologic agent of denture stomatitis. Candida hyphae exhibit the ability to respond directionally to environmental stimuli. This characteristic is thought to be important in the penetration of substrata such as resilient denture liners and host epithelium. It has been suggested that hyphal production also enhances adhesion and survival of Candida on host and denture surfaces. Surface roughness, in addition, can enhance adhesion where stronger interactions occur between cells and surface features of similar dimensions. The purpose of this study was to assess the development of hyphal and blastospore biofilms on abraded denture acrylic resin specimens and measure the ease of removal of these biofilms. Biofilms were grown for 48 hours on abraded 1-cm² denture acrylic resin specimens from adhered hyphal phase C albicans or from adhered blastospores. Subsequently, all specimens were stained with Calcofluor White and examined with confocal scanning laser microscopy. Biofilms were removed by vortex mixing in sterile phosphate buffered saline solution. Removed cells were filtered (0.2-μm pore size). Filters were dried at 37°C for 24 hours for dry weight measurements. Any cells that remained on the acrylic resin specimens were stained with 0.03% acridine orange and examined with epifluorescence microscopy. Biofilms grown from both cell types contained all morphologic forms of C albicans. Although the underlying surface topography did not affect the amount of biofilm produced, biofilms grown from hyphal phase Candida were visibly thicker and had greater biomass (Phyphae in early Candida biofilms increased biofilm mass and resistance to removal. Increased surface roughness enhances retention of hyphae and yeast cells, and, therefore, will facilitate plaque regrowth. Therefore, minimization of denture abrasion during cleaning is desirable. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All

Tungsten thick coatings for plasma facing components

International Nuclear Information System (INIS)

Riccardi, B.; Pizzuto, A.; Orsini, A.; Libera, S.; Visca, E.; Bertamini, L.; Casadei, F.; Severini, E.; Montanari, R.; Litunovsky, N.

1998-01-01

The aim of the R and D activity was to realize thick W coatings on CuCrZr hollow bars and to test the mock ups with respect to thermal fatigue. Eight mock ups provided of 4 mm thick W coating were finally manufactured. The bonding integrity between coating and substrate was checked by means of an Ultrasonic apparatus. Characterisation of coatings was performed in order to assess microstructure, impurity content, density, tensile strength, adhesion strength, thermal conductivity and thermal expansion coefficient. Macroscopic residual strain measurements were performed by means of 'hole drilling' technique. The activities performed demonstrated the feasibility of thick Tungsten coatings on geometries with more complex residual strain distribution. These coatings are reliable armour of medium heat flux plasma facing component. (author)

Investigation of the influence on residual stresses of porosity in high temperature ZrO2 coatings on Ag tape for magnet technologies

International Nuclear Information System (INIS)

Arman, Yusuf; Aktas, Mehmet; Celik, Erdal; Mutlu, Ibrahim H.; Sayman, Onur

2007-01-01

The present paper reports on the effect on residual stresses of porosity in high temperature ZrO 2 coatings on Ag tape for magnet technologies. ZrO 2 coatings were fabricated on Ag tape substrate using a reel-to-reel sol-gel system. The microstructural evolution of high temperature ZrO 2 coatings was investigated by a scanning electron microscope (SEM). SEM observations revealed that ZrO 2 coatings with crack had some porosity and mosaic structure. Stress analysis was carried out on ZrO 2 coatings with porosity on Ag tape substrates under cryogenic conditions by using classical lamination theory (CLT) for elastic solution and finite element method (FEM) for elasto-plastic solution in the temperature range of 0 o C to -223 o C in liquid helium media. Because of the static equilibrium, tensile force is applied to the Ag substrate, by ZrO 2 coating. The stress component (σ x ) values change rapidly at coating-substrate interface owing to the different moduli of elasticity and thermal expansion coefficient. In spite of the thickness of Ag substrate, the stress components vary from tensile to compressive. In addition, along the thickness of ZrO 2 coating and Ag substrate system, the stress distribution changes linearly. FEM results demonstrate that the failure does not occur in ZrO 2 coating for all porosities due to its high yield strength

X-ray analysis of residual stress gradients in TiN coatings by a Laplace space approach and cross-sectional nanodiffraction: a critical comparison.

Science.gov (United States)

Stefenelli, Mario; Todt, Juraj; Riedl, Angelika; Ecker, Werner; Müller, Thomas; Daniel, Rostislav; Burghammer, Manfred; Keckes, Jozef

2013-10-01

Novel scanning synchrotron cross-sectional nanobeam and conventional laboratory as well as synchrotron Laplace X-ray diffraction methods are used to characterize residual stresses in exemplary 11.5 µm-thick TiN coatings. Both real and Laplace space approaches reveal a homogeneous tensile stress state and a very pronounced compressive stress gradient in as-deposited and blasted coatings, respectively. The unique capabilities of the cross-sectional approach operating with a beam size of 100 nm in diameter allow the analysis of stress variation with sub-micrometre resolution at arbitrary depths and the correlation of the stress evolution with the local coating microstructure. Finally, advantages and disadvantages of both approaches are extensively discussed.

Stress analysis of thermal sprayed coatings using a semi-destructive hole-drilling strain gauge method

International Nuclear Information System (INIS)

Dolhof, V.; Musil, J.; Cepera, M.; Zeman, J.

1995-01-01

Residual stress is an important parameter in coating technology since it often relates to the maximum coating thickness which can be deposited without spallation, and this applies to coatings produced by different thermal spray and thin film technologies. Indeed, the mechanisms by which residual stress is built up or locked into a coating depends markedly on the deposition process and coating structure (growth structure, phase composition) in the same way too. Methods for determining residual stresses in materials include both destructive and non-destructive methods. This contribution describes semi-destructive hole-drilling strain gauge method modified for measurement of residual stresses in thermal sprayed coatings. This method of stress analysis was used for determination of stress levels in thermal sprayed WC-17% Co coatings onto 13% Cr steel substrates. Results show that deposition conditions and final coating structure influence directly the residual stress level in the coatings. It is proved that semi-destructive hole-tube drilling measurement is effective reproducible method of coating stress analysis and good solution for optimization of deposition process

Residual stress analysis in thick uranium films

International Nuclear Information System (INIS)

Hodge, A.M.; Foreman, R.J.; Gallegos, G.F.

2005-01-01

Residual stress analysis was performed on thick, 1-25 μm, depleted uranium (DU) films deposited on an Al substrate by magnetron sputtering. Two distinct characterization techniques were used to measure substrate curvature before and after deposition. Stress evaluation was performed using the Benabdi/Roche equation, which is based on beam theory of a bi-layer material. The residual stress evolution was studied as a function of coating thickness and applied negative bias voltage (0, -200, -300 V). The stresses developed were always compressive; however, increasing the coating thickness and applying a bias voltage presented a trend towards more tensile stresses and thus an overall reduction of residual stresses

Powder addition assessment of manganese residue ceramic matrix coating; Avaliacao da adicao do po de residuo de manganes em matriz ceramica para revestimento

Energy Technology Data Exchange (ETDEWEB)

Conceicao, A.C.R. da; Santos, O.C.; Leao, M.A., E-mail: arangel-ma@hotmail.com [Instituto Federal de Educacao, Ciencia e Tecnologia da Bahia (IFBA), BA (Brazil)

2016-07-01

The use of recycled materials in the composition of new products follows the production's worldwide trending, meeting new technological requirements and environmental concerns. This work aims to utilize the residue of manganese dust on ceramic mass for the production of ceramic coating. The raw materials were characterized by both x-ray fluorescence and diffraction. The powder residue added to clay in the percentage of 0%, 5%, 10% and 15% (measured in weight) was compressed by a uniaxial pressing of 30MPa and the sintering temperatures were 900°, 1000° and 1100°. The samples were analysed in relation to flexural strength, bulk density, water absorption and linear shrinkage. The microstructural variation was also analysed by x-ray diffraction and electron microscopy. The results showed that there is a viability for the production of porcelain ceramic coating (A3 and A4 formulations) and stoneware (A2 formulation) according to the specification of technical standards. author)

Anti-icing properties of superhydrophobic ZnO/PDMS composite coating

Science.gov (United States)

Yang, Chao; Wang, Fajun; Li, Wen; Ou, Junfei; Li, Changquan; Amirfazli, Alidad

2016-01-01

We present the excellent anti-icing performance for a superhydrophobic coating surface based on ZnO/polydimethylsiloxane (ZnO/PDMS) composite. The superhydrophobic ZnO/PDMS coating surface was prepared by a facile solution mixing, drop coating, room-temperature curing and surface abrading procedure. The superhydrophobic ZnO/PDMS composite coating possesses a water contact angle of 159.5° and a water sliding angle of 8.3° at room temperature (5 °C). The anti-icing properties of the superhydrophobic coating were investigated by continuously dropping cold-water droplets (about 0 °C) onto the pre-cooled surface using a home-made apparatus. The sample was placed at different tilting angle (0° and 10°) and pre-cooled to various temperatures (-5, -10 and -15 °C) prior to measure. The pure Al surface was also studied for comparison. It was found that icing accretion on the surface could be reduced apparently because the water droplets merged together and slid away from the superhydrophobic surface at all of the measuring temperatures when the surface is horizontally placed. In addition, water droplet slid away completely from the superhydrophobic surface at -5 and -10 °C when the surface is tilted at 10°, which demonstrates its excellent anti-icing properties at these temperatures. When the temperature decreased to -15 °C, though ice accretion on the tilted superhydrophobic coating surface could not be avoided absolutely, the amount of ice formed on the surface is very small, which indicated that the coating surface with superhydrophobicity could significantly reduce ice accumulation on the surface at very low temperature (-15 °C). Importantly, the sample is also stable against repeated icing/deicing cycles. More meaningfully, once the superhydrophobic surface is damaged, it can be repaired easily and rapidly.

Low residual diet and hydration improving double contrast examination of the colon

International Nuclear Information System (INIS)

Virkki, R.; Maekelae, P.

1983-01-01

Light food diet and low residual diet with hydration, both combined with Proctosal and Bisacodyl cleansing, were compared in 268 patients in the preparation of the colon for double contrast examination. Low residual diet with hydration resulted in significantly less residual fecal material, no flocculation of the barium coating and significantly denser mucosal coating. The examination had to be repeated more often (8.6%) after light food diet than after low residual diet with hydration (1.7%), but there was no statistically significant difference in the diagnostic accuracy. The hydration is important in avoiding patient discomforts and flocculation of the barium coating. Despite the use of laxatives, a strict diet restriction is needed to obtain consistently clean colon. (orig.)

Neutron residual stress measurements in linepipe

International Nuclear Information System (INIS)

Law, Michael; Gnaepel-Herold, Thomas; Luzin, Vladimir; Bowie, Graham

2006-01-01

Residual stresses in gas pipelines are generated by manufacturing and construction processes and may affect the subsequent pipe integrity. In the present work, the residual stresses in eight samples of linepipe were measured by neutron diffraction. Residual stresses changed with some coating processes. This has special implications in understanding and mitigating stress corrosion cracking, a major safety and economic problem in some gas pipelines

Application of the whole powder pattern decomposition procedure in the residual stress analysis of layers and coatings

International Nuclear Information System (INIS)

Schoderböck, Peter; Brechbühl, Jens

2015-01-01

The X-ray investigation of stress states in materials, based on the determination of elastic lattice strains which are converted to stresses by means of theory of elasticity, is a necessity in quality control of thin layers and coatings for optimizing manufacturing steps and process parameters. This work introduces the evaluation of residual stress from complex and overlapping diffraction patterns using a whole-powder pattern decomposition procedure defining a 2θ-offset caused by residual stresses. Furthermore corrections for sample displacement and refraction are directly implemented in the calculation procedure. The correlation matrices of the least square fitting routines have been analyzed for parameter interactions and obvious interdependencies have been decoupled by the introduction of an internal standard within the diffraction experiment. This decomposition based evaluation has been developed on tungsten as a model material system and its efficiency was demonstrated by X-ray diffraction analysis of a solid oxide fuel cell multilayer system. The results are compared with those obtained by the classical sin 2 Ψ-method. - Highlights: • Analysis of complex multiphase diffraction patterns with respect to residual stress • Stress-gradient determination with in situ correction of displacement and refraction • Consideration of the elastic anisotropy within the refinement

The improvement of adhesive properties of PEEK through different pre-treatments

Science.gov (United States)

Hallmann, Lubica; Mehl, Albert; Sereno, Nuno; Hämmerle, Christoph H. F.

2012-07-01

The purpose of this in vitro study was the evaluation of the bond strength of the adhesives/composite resin to Poly Ether Ether Ketone (PEEK) based dental polymer after using different surface conditioning methods. PEEK blanks were cut into discs. All disc specimens were polished with 800 grit SiC paper and divided into 6 main groups. Main groups were divided into 2 subgroups. The main groups of 32 specimens each were treated as follow: (1) control specimens (no treatment), (2) piranha solution etching, (3) abraded with 50 μm alumina particles and chemical etching, (4) abraded with 110 μm alumina particles and chemical etching, (5) abraded with 30 μm silica-coated alumina particles and chemical etching, (6) abraded with 110 μm silica-coated alumina particles and chemical etching. Plexiglas tubes filled with a composite resin (RelyX Unicem) were bonded to the specimens. The adhesives used were Heliobond and Clearfil Ceramic Primer. Each specimen was stored in distilled water (37 °C) for 3 days. Tensile bond strength was measured in a universal testing machine and failure methods were evaluated. Abraded surface with 50 μm alumina particles followed by etching with piranha solution lead to the highest bond strength of 21.4 MPa when Heliobond like adhesive was used. Tribochemical silica coated/etched PEEK surfaces did not have an effect on the bond strength. Non-treated PEEK surface was not able to establish a bond with composite resin. The proper choice of adhesive/composite resin system leads to a strong bond. ConclusionAirborne particle abrasion in combination with piranha solution etching improves the adhesive properties of PEEK.

Thermal shock behavior of platinum aluminide bond coat/electron beam-physical vapor deposited thermal barrier coatings

Energy Technology Data Exchange (ETDEWEB)

Xu, Zhenhua, E-mail: zhxuciac@163.com [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); Dai, Jianwei [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); Niu, Jing [Shenyang Liming Aero-engine (Group) Corporation Ltd., Institute of Metallurgical Technology, Technical Center, Shengyang 110043 (China); Li, Na; Huang, Guanghong; He, Limin [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China)

2014-12-25

Highlights: • TBCs of (Ni, Pt)Al bond coat with grit blasting process and YSZ ceramic coating. • Grain boundary ridges are the sites for spallation damage initiation in TBCs. • Ridges removed, cavities formation appeared and the damage initiation deteriorated. • Damage initiation and progression at interface lead to a buckling failure. - Abstract: Thermal barrier coating systems (TBCs) including of chemical vapor deposited (Ni, Pt)Al bond coat with grit blasting process and electron beam physical vapor deposited Y{sub 2}O{sub 3}-stabilized-ZrO{sub 2} (YSZ) ceramic coating were investigated. The phase structures, surface and cross-sectional morphologies, thermal shock behaviors and residual stresses of the coatings were studied in detail. Grain boundary ridges still remain on the surface of bond coat prior to the deposition of the ceramic coating, which are shown to be the major sites for spallation damage initiation in TBCs. When these ridges are mostly removed, they appear some of cavities formation and then the damage initiation mode is deteriorated. Damage initiation and progression occurs at the bond coat to thermally grown oxide (TGO) interface leading to a buckling failure behavior. A buckle failure once started may be arrested when it runs into a region of high bond coat to TGO interface toughness. Thus, complete failure requires further loss in toughness of the bond coat to TGO interface during cooling. The suppressed cavities formation, the removed ridges at the grain boundaries, the relative high TGO to bond coat interface toughness, the uniform growth behavior of TGO thickening and the lower of the residual stress are the primary factors for prolonging the lifetime of TBCs.

FEM simulation study on relationship of interfacial morphology and residual stress in TBCs

Energy Technology Data Exchange (ETDEWEB)

Liqiang Chen; Shengkai Gong; Huibin Xu [School of Materials Science and Engineering, Beihang Univ., Beijing, BJ (China)

2005-07-01

It is generally believed that the failure of TBCs is attributed to the spallation occurred in the ceramic coat. The spallation is closed linked with sinuate morphology factors, including its amplitude and period, at the TGO/bond coat interface. In this work, dependence of the residual stress distribution on the sinuate morphology in the TBCs has been studied by means of finite element method (FEM) simulation for isothermally annealed specimens. The simulation results indicated that the maximum value of residual stress existed inside the TGO layer. It was also found that the maximum residual stress occurred at different points, near the TGO/bond coat interface at the peak of the sinuate interface, while near the TGO/ceramic coat interface at the valley, respectively. And the maximum residual stress increased with increasing the ratio of the amplitude to period in the sine morphology, which has been proved by the thermal cycle experimental results. (orig.)

Deposition stress effects on thermal barrier coating burner rig life

Science.gov (United States)

Watson, J. W.; Levine, S. R.

1984-01-01

A study of the effect of plasma spray processing parameters on the life of a two layer thermal barrier coating was conducted. The ceramic layer was plasma sprayed at plasma arc currents of 900 and 600 amps onto uncooled tubes, cooled tubes, and solid bars of Waspalloy in a lathe with 1 or 8 passes of the plasma gun. These processing changes affected the residual stress state of the coating. When the specimens were tested in a Mach 0.3 cyclic burner rig at 1130 deg C, a wide range of coating lives resulted. Processing factors which reduced the residual stress state in the coating, such as reduced plasma temperature and increased heat dissipation, significantly increased coating life.

Silica-Based and Borate-Based, Titania-Containing Bioactive Coatings Characterization: Critical Strain Energy Release Rate, Residual Stresses, Hardness, and Thermal Expansion

Directory of Open Access Journals (Sweden)

Omar Rodriguez

2016-12-01

Full Text Available Silica-based and borate-based glass series, with increasing amounts of TiO2 incorporated, are characterized in terms of their mechanical properties relevant to their use as metallic coating materials. It is observed that borate-based glasses exhibit CTE (Coefficient of Thermal Expansion closer to the substrate’s (Ti6Al4V CTE, translating into higher mode I critical strain energy release rates of glasses and compressive residual stresses and strains at the coating/substrate interface, outperforming the silica-based glasses counterparts. An increase in the content of TiO2 in the glasses results in an increase in the mode I critical strain energy release rate for both the bulk glass and for the coating/substrate system, proving that the addition of TiO2 to the glass structure enhances its toughness, while decreasing its bulk hardness. Borate-based glass BRT3, with 15 mol % TiO2 incorporated, exhibits superior properties overall compared to the other proposed glasses in this work, as well as 45S5 Bioglass® and Pyrex.

Diffraction grating strain gauge method: error analysis and its application for the residual stress measurement in thermal barrier coatings

Science.gov (United States)

Yin, Yuanjie; Fan, Bozhao; He, Wei; Dai, Xianglu; Guo, Baoqiao; Xie, Huimin

2018-03-01

Diffraction grating strain gauge (DGSG) is an optical strain measurement method. Based on this method, a six-spot diffraction grating strain gauge (S-DGSG) system has been developed with the advantages of high and adjustable sensitivity, compact structure, and non-contact measurement. In this study, this system is applied for the residual stress measurement in thermal barrier coatings (TBCs) combining the hole-drilling method. During the experiment, the specimen’s location is supposed to be reset accurately before and after the hole-drilling, however, it is found that the rigid body displacements from the resetting process could seriously influence the measurement accuracy. In order to understand and eliminate the effects from the rigid body displacements, such as the three-dimensional (3D) rotations and the out-of-plane displacement of the grating, the measurement error of this system is systematically analyzed, and an optimized method is proposed. Moreover, a numerical experiment and a verified tensile test are conducted, and the results verify the applicability of this optimized method successfully. Finally, combining this optimized method, a residual stress measurement experiment is conducted, and the results show that this method can be applied to measure the residual stress in TBCs.

Using of sawing quartzite fine residual for obtaining ceramic coating; Utilizacao do residuo fino da serragem de quartzito para obtencao de revestimento ceramico

Energy Technology Data Exchange (ETDEWEB)

Nobrega, L.F.P.M.; Souza, M.M., E-mail: junior.luiz09@hotmail.com [Universidade Federal do Rio Grande do Norte (DIAREN/UFRN), Natal, RN (Brazil). Laboratorio de Processamento Mineral e Residuo

2016-07-01

Quartzite is a metamorphic rock that is consisting mainly of quartz. In Paraiba there is a mining activity of this rock, in the region of Varzea and Junco do Serido especially where many wastes are created, including the sawing residue. The objective is to use the waste cited as the ceramic component coating mass, thereby replacing the quartz. Initially, the raw materials samples were taken and the chemical analysis was done of them. This passed the comminution process to achieve the required minimum particle size. After this, a formulation which added the residue in ceramic mass was made. The specimens were subjected to sintering and it was later made physical tests according to NBR 13818. The results show that the residue can replace the quartz ceramic mass successfully, but not as good as the original raw material. (author)

Oral coatings: a study on the formation, clearance and perception

NARCIS (Netherlands)

Camacho, S.

2015-01-01

Oral coatings are residues of food and beverages that coat the oral mucosa after consumption. Several studies have reported on the lubrication properties in mouth, and the after-feel and after-taste impact of oral coatings. Further, oral coatings have been suggested to influence subsequent taste

Performance characterization of metallic substrates coated by HVOF WC–Co

International Nuclear Information System (INIS)

Venter, Andrew M.; Oladijo, O. Philip; Luzin, Vladimir; Cornish, Lesley A.; Sacks, Natasha

2013-01-01

Integral to the performance of high-velocity oxygen-fuel (HVOF) coatings is the thermo-mechanical interaction associated with the thermal misfit, or differences in thermal expansion coefficients (CTEs), between coating and substrate. This investigation reports results on the microstructures, chemical phase content, coating–substrate misfit residual stress, and wear resistance. For this purpose a systematic characterization of WC–Co sprayed coatings on a number of substrates covering a range of CTE values were pursued for both the as-coated and heat-treated conditions. The neutron diffraction technique in conjunction with sub-millimeter sized gauge volumes enabled depth-resolved studies of the stress in the coatings and substrates by paying special attention to the determination of the stress contribution attributed by the final spray process. In the as-coated condition the stress values in the coatings were compressive for CTEs larger than that of WC–Co and tensile for CTE lower than WC–Co. Wear resistance increased for increased compressive stress and macrohardness. In the heat-treated condition, this trend became enhanced due to increased compressive stress in the coatings. - Highlights: • Four different substrate systems coated with HVOF WC-Co has been investigated. • Each substrate set encompassed the grit-blast surface and as-coated conditions, as well as their heat-treated counterparts. • Microstructural, macrohardness, wear performance and depth-resolved residual stress characterised. • Successful application of neutron strain scanning to investigating the combined systems, coatings and substrates. • Link observed between macrohardness, residual stress and wear performance

Design and optimization of coating structure for the thermal barrier coatings fabricated by atmospheric plasma spraying via finite element method

Directory of Open Access Journals (Sweden)

L. Wang

2014-06-01

Full Text Available The first prerequisite for fabricating the thermal barrier coatings (TBCs with excellent performance is to find an optimized coating structure with high thermal insulation effect and low residual stress. This paper discusses the design and optimization of a suitable coating structure for the TBCs prepared by atmospheric plasma spraying (APS using the finite element method. The design and optimization processes comply with the rules step by step, as the structure develops from a simple to a complex one. The research results indicate that the suitable thicknesses of the bond-coating and top-coating are 60–120 μm and 300–420 μm, respectively, for the single ceramic layer YSZ/NiCoCrAlY APS-TBC. The embedded interlayer (50 wt.%YSZ + 50 wt.%NiCoCrAlY will further reduce the residual stress without sacrificing the thermal insulation effect. The double ceramic layer was further considered which was based on the single ceramic layer TBC. The embedded interlayer and the upper additional ceramic layer will have a best match between the low residual stress and high thermal insulation effect. Finally, the optimized coating structure was obtained, i.e., the La2Ce2O7(LC/YSZ/Interlayer/NiCoCrAlY coating structure with appropriate layer thickness is the best choice. The effective thermal conductivity of this optimized LC/YSZ/IL/BL TBC is 13.2% lower than that of the typical single ceramic layer YSZ/BL TBC.

Outgassing characteristics of TiC coated materials

International Nuclear Information System (INIS)

Sukenobu, S.; Gomay, Y.

1982-01-01

The outgassing characteristics of TiC-coated materials (POCO graphite, and molybdenum) were studied. In the case of molybdenum substrate, thin TiN layer was coated before TiC coating to avoid molybdenum carbide formation. The outgassing characteristics of the sample materials were studied by a baking process at 250 degree C for 24 hours. The samples were inserted in a 304 stainless steel vacuum chamber with a thin aperture, and the gas through-put from this chamber was estimated by measuring the pressure before and after the aperture. A residual gas analyzer was installed on the low pressure side of the aperture. It can be concluded that the out-gassing rate of these TiC-coated materials was about 10 -12 Torr.Fl/s.Fcm"2 after baking at 250 degree C for 24 hours. Residual gas analysis showed that the main outgas species were H 2 and CO after baking. The TiC-coated POCO graphite and molybdenum are applicable to fusion devices as far as the outgassing characteristics are concerned. (Kato, T.)

Investigation of the Effect of Residual Stress Gradient on the Wear Behavior of PVD Thin Films

Science.gov (United States)

Tlili, B.; Nouveau, C.; Guillemot, G.; Besnard, A.; Barkaoui, A.

2018-02-01

The control of residual stresses has been seldom investigated in multilayer coatings dedicated to improvement of wear behavior. Here, we report the preparation and characterization of superposed structures composed of Cr, CrN and CrAlN layers. Nano-multilayers CrN/CrAlN and Cr/CrN/CrAlN were deposited by Physical Vapor Deposition (PVD) onto Si (100) and AISI4140 steel substrates. The Cr, CrN and CrAlN monolayers were developed with an innovative approach in PVD coatings technologies corresponding to deposition with different residual stresses levels. Composition and wear tracks morphologies of the coatings were characterized by scanning electron microscopy, high-resolution transmission electron microscopy, atomic force microscopy, x-ray photoelectron spectroscopy, energy-dispersive x-ray spectroscopy, x-ray diffraction and 3D-surface analyzer. The mechanical properties (hardness, residual stresses and wear) were investigated by nanoindentation, interferometry and micro-tribometry (fretting-wear tests). Observations suggest that multilayer coatings are composed mostly of nanocrystalline. The residual stresses level in the films has practically affected all the physicochemical and mechanical properties as well as the wear behavior. Consequently, it is demonstrated that the coating containing moderate stresses has a better wear behavior compared to the coating developed with higher residual stresses. The friction contact between coated samples and alumina balls shows also a large variety of wear mechanisms. In particular, the abrasive wear of the coatings was a combination of plastic deformation, fine microcracking and microspallation. The application of these multilayers will be wood machining of green wood.

Multilayer DLC coatings via alternating bias during magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Li Fengji [School of Mechanical and Aerospace Engineering, Nanyang Technological University (Singapore); Zhang, Sam, E-mail: msyzhang@ntu.edu.sg [School of Mechanical and Aerospace Engineering, Nanyang Technological University (Singapore); Kong Junhua [School of Materials Science and Engineering, Nanyang Technological University (Singapore); Zhang Yujuan [Key Laboratory of Special Functional Material, Henan University (China); Zhang Wali [School of Mechanical and Aerospace Engineering, Nanyang Technological University (Singapore)

2011-05-31

To combat the high residual stress problem in monolayer diamond-like carbon coatings, this paper fabricated multilayer diamond-like carbon coatings with alternate soft and hard layers via alternating bias during magnetron sputtering. The surface, cross sectional morphology, bonding structures and mechanical properties are investigated. The atomic force microscopy images indicate low bias results in rougher surface with large graphite clusters and voids suggesting low coating density. The multilayered coatings demonstrate relatively smooth surface stemming from higher bias. The cross sectional images from field emission scanning electron microscopy indicate coating thickness decreases as substrate bias increases and confirm that higher bias results in denser coating. Delamination is observed in monolayer coatings due to high residual stress. The trend of sp{sup 3}/sp{sup 2} fraction estimated by X-ray photoelectron spectroscopy is consistent with that of I{sub D}/I{sub G} ratios from Raman spectra, indicating the change of bonding structure with change of substrate bias. Hardness of multilayer diamond-like carbon coating is comparable to the coatings deposited at low constant bias but the adhesion strength and toughness are significantly improved. Alternately biased sputtering deposition provides an alternative when combination of hardness, toughness and adhesion strength is needed in an all diamond-like carbon coating.

Oral coatings: a study on the formation, clearance and perception

OpenAIRE

Camacho, S.

2015-01-01

Oral coatings are residues of food and beverages that coat the oral mucosa after consumption. Several studies have reported on the lubrication properties in mouth, and the after-feel and after-taste impact of oral coatings. Further, oral coatings have been suggested to influence subsequent taste perception. Although it is well known that oral coatings can influence sensory perception, there was little information available on the chemical composition and physical properties of oral coatings. ...

A mechanical impact of coatings on membranes

DEFF Research Database (Denmark)

Hansen, Michael Søren; Reus, Roger De; Eriksen, Gert Friis

2001-01-01

The mechanical impact of coatings containing residual stress on membranes is investigated. Closed-form formulas describing this impact are presented and verified using both finite element modeling and physical experiments. Theory and experiments are in good agreement. Thus, a simple tool for design...... of coated pressure sensors is provided....

Performance of candidate gas turbine abradeable seal materials in high temperature combustion atmospheres

Energy Technology Data Exchange (ETDEWEB)

Simms, N.J. [Cranfield University, Power Generation Technology Centre, Cranfield, Beds, MK43 0AL (United Kingdom); Norton, J.F. [Cranfield University, Power Generation Technology Centre, Cranfield, Beds, MK43 0AL (United Kingdom); Consultant in Corrosion Science and Technology, Hemel Hempstead, Herts HP1 1SR (United Kingdom); McColvin, G. [Siemens Industrial Turbines Ltd., Lincoln, LN5 7FD (United Kingdom)

2005-11-01

The development of abradeable gas turbine seals for higher temperature duties has been the target of an EU-funded R and D project, ADSEALS, with the aim of moving towards seals that can withstand surface temperatures as high as {proportional_to} 1100 C for periods of at least 24,000 h. The ADSEALS project has investigated the manufacturing and performance of a number of alternative materials for the traditional honeycomb seal design and novel alternative designs. This paper reports results from two series of exposure tests carried out to evaluate the oxidation performance of the seal structures in combustion gases and under thermal cycling conditions. These investigations formed one part of the evaluation of seal materials that has been carried out within the ADSEALS project. The first series of three tests, carried out for screening purposes, exposed candidate abradeable seal materials to a simulated natural gas combustion environment at temperatures within the range 1050-1150 C in controlled atmosphere furnaces for periods of up to {proportional_to} 2,500 h with fifteen thermal cycles. The samples were thermally cycled to room temperature on a weekly basis to enable the progress of the degradation to be monitored by mass change and visual observation, as well as allowing samples to be exchanged at planned intervals. The honeycombs were manufactured from PM2000 and Haynes 214. The backing plates for the seal constructions were manufactured from Haynes 214. Some seals contained fillers or had been surface treated (e.g. aluminised). The second series of three tests were carried out in a natural gas fired ribbon furnace facility that allowed up to sixty samples of candidate seal structures (including honeycombs, hollow sphere structures and porous ceramics manufactured from an extended range of materials including Aluchrom YHf, PM2Hf, Haynes 230, IN738LC and MarM247) to be exposed simultaneously to a stream of hot combustion gas. In this case the samples were cooled

Long-term Bond Strength between Layering Indirect Composite Material and Zirconia Coated with Silicabased Ceramics.

Science.gov (United States)

Fushiki, Ryosuke; Komine, Futoshi; Honda, Junichi; Kamio, Shingo; Blatz, Markus B; Matsumura, Hideo

2015-06-01

This study evaluated the long-term shear bond strength between an indirect composite material and a zirconia framework coated with silica-based ceramics, taking the effect of different primers into account. A total of 165 airborne-particle abraded zirconia disks were subjected to one of three pretreatments: no pretreatment (ZR-AB), airborne-particle abrasion of zirconia coated with feldspathic porcelain (ZR-PO-AB), and 9.5% hydrofluoric acid etching of zirconia coated with feldspathic porcelain (ZR-PO-HF). An indirect composite material (Estenia C&B) was then bonded to the zirconia disks after they were treated with one of the following primers: Clearfil Photo Bond (CPB), Clearfil Photo Bond with Clearfil Porcelain Bond Activator (CPB + Activator), Estenia Opaque Primer (EOP), Porcelain Liner M Liquid B (PLB), or no priming (CON, control group). Shear bond strength was tested after 100,000 thermocycles, and the data were analyzed using the Steel-Dwass U-test (α = 0.05). For ZR-PO-AB and ZR-PO-HF specimens, bond strength was highest in the CPB+Activator group (25.8 MPa and 22.4 MPa, respectively). Bond strengths were significantly lower for ZR-AB specimens in the CON and PLB groups and for ZR-PO-AB specimens in the CON, CPB, and EOP groups. Combined application of a hydrophobic phosphate monomer (MDP) and silane coupling agent enhanced the long-term bond strength of indirect composite material to a zirconia coated with silica-based ceramics.

The use of neutron diffraction for the determination of the in-depth residual stresses profile in weld coatings; A utilizacao da difracao de neutroes na determinacao do perfil de tensoes residuais em revestimentos por soldadura

Energy Technology Data Exchange (ETDEWEB)

Marques, Maria Jose; Batista, A.C.; Nobre, J.P. [Universidade de Coimbra (Portugal). Dept. de Fisica. Centro de Estudos de Materiais por Difraccao de Raios X (CEMDRX); Loureiro, Altino [Universidade de Coimbra (Portugal). Dept. de Engenharia Mecanica. Centro de Engenharia Mecanica (CEMUC); Kornmeier, Joana R., E-mail: mjvaz@fe.up.pt [Technische Universitaet Muenchen, Garching (Germany). FRM II

2013-04-15

The neutron diffraction is a non-destructive technique, particularly suitable for the analysis of residual stress fields in welds. The technique is used in this article to study ferritic samples, coated by submerged arc welding using stainless steel filler metals. This procedure is often used for manufacturing process equipment for chemical and nuclear industries, for ease of implementation and economic reasons. The main disadvantage of that processes is the cracking phenomenon that often occurs at the interface between the base material and coatings, which can be minimized by performing post-weld stress relief heat treatments. The samples analyzed in this study were made of carbon steel plates, coated by submerged arc welding two types of stainless steel filler metals. For the first layer was used one EN 12 072 - S 2 U 23 12 electrode, while for the second and third layers were used an EN 12 072 - 19 12 3 S L electrode. After cladding, the samples were submitted to a post-weld heat treatment for 1 hour at 620 deg C. The residual stress profiles obtained by neutron diffraction evidence the relaxation of residual stress given by the heat treatment. (author)

Residual stress distribution analysis of heat treated APS TBC using image based modelling.

Science.gov (United States)

Li, Chun; Zhang, Xun; Chen, Ying; Carr, James; Jacques, Simon; Behnsen, Julia; di Michiel, Marco; Xiao, Ping; Cernik, Robert

2017-08-01

We carried out a residual stress distribution analysis in a APS TBC throughout the depth of the coatings. The samples were heat treated at 1150 °C for 190 h and the data analysis used image based modelling based on the real 3D images measured by Computed Tomography (CT). The stress distribution in several 2D slices from the 3D model is included in this paper as well as the stress distribution along several paths shown on the slices. Our analysis can explain the occurrence of the "jump" features near the interface between the top coat and the bond coat. These features in the residual stress distribution trend were measured (as a function of depth) by high-energy synchrotron XRD (as shown in our related research article entitled 'Understanding the Residual Stress Distribution through the Thickness of Atmosphere Plasma Sprayed (APS) Thermal Barrier Coatings (TBCs) by high energy Synchrotron XRD; Digital Image Correlation (DIC) and Image Based Modelling') (Li et al., 2017) [1].

Residual stress in ion implanted titanium nitride studied by parallel beam glancing incidence x-ray diffraction

International Nuclear Information System (INIS)

Geist, D.E.; Perry, A.J.; Treglio, J.R.; Valvoda, V.; Rafaja, D.

1995-01-01

Ion implantation is known to increase the lifetime of cutting tools. Current theories are the increase in lifetime is caused by an increase in the residual stress, or by work hardening of the surface associated with the implantation. In this work the effect of ion implantation on the residual stress in titanium nitride coatings made by the standard industrial methods of chemical and physical vapor deposition (CVD and PVD) is studied. It is found in the as-received condition (unimplanted), the residual stress levels are near zero for CVD materials and highly compressive, of the order of 6 GPa, for PVD materials. Ion implantation has no effect on the residual stress in the coatings made by CVD. Nitrogen does increase the compressive residual stress by some 10% in the near surface regions of PVD coatings, while nickel-titanium dual metal ion implantation does not have any effect. It appears that the lifetime increase is not associated with residual stress effects

Cellulose acetate propionate coated titanium: characterization and biotechnological application

Directory of Open Access Journals (Sweden)

Guilherme da Silva Gomes

2007-12-01

Full Text Available Surfaces of pure titanium and Ti coated with cellulose acetate propionate (CAP have been characterized by means of scanning electron microscopy X ray coupled with elemental microanalysis (SEM-EDS, ellipsometry, atomic force microscopy (AFM and contact angle measurements. Coating Ti surfaces with CAP ultrathin films reduced original surface roughness. Surface energy and wettability of CAP covered Ti surfaces pure Ti surfaces were similar. The adsorption of lysozyme (LYZ, an antibacterial protein, onto Ti and CAP-coated Ti surfaces has been studied by means of ellipsometry and atomic force microscopy (AFM. The adsorption of LYZ was mainly driven by hydrophobic interaction between protein hydrophobic residues and CAP propyl groups. Pure Ti and CAP coated Ti surfaces presented no cytotoxicity effect and proved to be adequate substrates for cell adhesion. The biocompatibility of CAP coated Ti surfaces was attributed to the surface enrichment in glucopyranosyl residues and short alkyl side groups.

High-temperature strength of TiC-coated SUS316 stainless steel

International Nuclear Information System (INIS)

Kaneko, K.; Furuya, Y.; Kikuchi, M.

1992-01-01

Some ceramics-coated metals are nominated as first-wall material. TiC-coated type 316 stainless steel is expected to be superior to other materials in high-temperature strength and in its endurance properties at heavy irradiation. Delamination between ceramics layer and base-metal is considered to be one of the most important problems when such ceramics-coated metals are used in a temperature field with a gradient such as that of the first wall. In this report, the high-temperature strength of TiC-coated type 316 stainless steel, which should be that of the first wall of the fusion reactor, is investigated experimentally and computationally. A simple and precise thermal-stress testing system is developed. The effects of surface roughness as well as of the thermal stress and the residual stress on the bonding strength are investigated. The experimental and numerical results on the residual-stress distribution are compared with each other to confirm the reliability of the inelastic analysis using the finite-element method (FEM). It is expected that a suitable surface roughness makes the residual stress in the coated film small. The optimum range for the TiC-coating temperature is found using inelastic FEM analysis at the heating conditions used in the experiments. (orig.)

Deposition stress effects on the life of thermal barrier coatings on burner rigs

Science.gov (United States)

Watson, J. W.; Levine, S. R.

1984-01-01

A study of the effect of plasma spray processing parameters on the life of a two layer thermal barrier coating was conducted. The ceramic layer was plasma sprayed at plasma arc currents of 900 and 600 amps onto uncooled tubes, cooled tubes, and solid bars of Waspalloy in a lathe with 1 or 8 passes of the plasma gun. These processing changes affected the residual stress state of the coating. When the specimens were tested in a Mach 0.3 cyclic burner rig at 1130 deg C, a wide range of coating lives resulted. Processing factors which reduced the residual stress state in the coating, such as reduced plasma temperature and increased heat dissipation, significantly increased coating life.

Deposition and Characterization of HVOF Thermal Sprayed Functionally Graded Coatings Deposited onto a Lightweight Material

Science.gov (United States)

Hasan, M.; Stokes, J.; Looney, L.; Hashmi, M. S. J.

2009-02-01

There is a significant interest in lightweight materials (like aluminum, magnesium, titanium, and so on) containing a wear resistance coating, in such industries as the automotive industry, to replace heavy components with lighter parts in order to decrease vehicle weight and increase fuel efficiency. Functionally graded coatings, in which the composition, microstructure, and/or properties vary gradually from the bond coat to the top coat, may be applied to lightweight materials, not only to decrease weight, but also to enhance components mechanical properties by ensuring gradual microstructural (changes) together with lower residual stress. In the current work, aluminum/tool-steel functionally graded coatings were deposited onto lightweight aluminum substrates. The graded coatings were then characterized in terms of residual stress and hardness. Results show that residual stress increased with an increase in deposition thickness and a decrease in number of layers. However, the hardness also increased with an increase in deposition thickness and decrease in number of layers. Therefore, an engineer must compromise between the hardness and stress values while designing a functionally graded coating-substrate system.

Study by X-ray diffraction and mechanical analysis of the residual stress generation during thermal spraying

International Nuclear Information System (INIS)

Pina, J.; Dias, A.; Lebrun, J.L.

2003-01-01

Thermally sprayed coatings are formed by the deposition of molten or partially molten particles, propelled onto a substrate where they impact, spread and solidify rapidly. Residual stresses are expected within the sprayed deposit as a consequence of the release of thermal and kinetic energies. A wide range of materials and two spraying techniques are considered in this study, namely atmospheric plasma spraying (APS) and high-velocity oxygen fuel. Stresses were determined by the X-ray diffraction (XRD) method. The results were compared with those calculated by mechanical analysis of stress relief in coatings detached from the substrate. Comparison of the results for adherent and free-standing coatings shows that the residual stress state can be resolved in terms of the components suggested by models that propose two stages of stress generation: quenching stresses and secondary-cooling stresses. The in-depth distribution of residual stresses, through the coating thickness, is discussed in terms of the nature of the coating system

Aluminum and Other Coatings for the Passivation of Tritium Storage Vessels

Energy Technology Data Exchange (ETDEWEB)

Spencer, W. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Korinko, P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2016-11-16

Using a highly sensitive residual gas analyzer, the off-gassing of hydrogen, water, and hydrocarbons from surface-treated storage vessels containing deuterium was measured. The experimental storage vessels were compared to a low-off-gassing, electro-polished 304L canister. Alternative vessels were made out of aluminum, or were coatings on 304L steel. Coatings included powder pack aluminide, electro-plated aluminum, powder pack chromide, dense electro-plated chromium, copper plated, and copper plated with 25 and 50 percent nano-diamond. Vessels were loaded with low pressure deuterium to observe exchange with protium or hydrogen as observed with formation of HD and HDO. Off gas of D₂O or possible CD₄ was observed at mass 20. The main off-gas in all of the studies was H₂. The studies indicated that coatings required significant post-coating treatment to reduce off-gas and enhance the permeation barrier from gases likely added during the coating process. Dense packed aluminum coatings needed heating to drive off water. Electro-plated aluminum, chromium and copper coatings appeared to trap hydrogen from the plating process. Nano-diamond appeared to enhance the exchange rate with hydrogen off gas, and its coating process trapped significant amounts of hydrogen. Aluminum caused more protium exchange than chromium-treated surfaces. Aluminum coatings released more water, but pure aluminum vessels released small amounts of hydrogen, little water, and generally performed well. Chromium coating had residual hydrogen that was difficult to totally outgas but otherwise gave low residuals for water and hydrocarbons. Our studies indicated that simple coating of as received 304L metal will not adequately block hydrogen. The base vessel needs to be carefully out-gassed before applying a coating, and the coating process will likely add additional hydrogen that must be removed. Initial simple bake-out and leak checks up to 350° C for a few hours was

ANTIREFLECTION MULTILAYER COATINGS WITH THIN METAL LAYERS

Directory of Open Access Journals (Sweden)

L. A. Gubanova

2016-03-01

Full Text Available The design of anti-reflective coatings for metal surfaces of Al, Ti, N,i Cr is proposed. The coatings have the form of alternating layers of dielectric/metal/dielectric with the number of cells up to15. The method of calculation of such coatings is proposed. We have calculated the coatings of the type [HfO2/Cr/HfO2]15, [ZrO2/Ti/Al2O3]15, [ZrO2/Cr/ZrO2]15. It is shown that the proposed interference coatings provide reduction of the residual reflectance of the metal several times (from 3.5 to 6.0 in a wide spectral range (300-1000 nm. The proposed coatings can be recommended as anti-reflective coatings for energy saving solar systems and batteries, and photovoltaic cells.

Influence of current density on microstructure and properties of electrodeposited nickel-alumina composite coatings

International Nuclear Information System (INIS)

Góral, Anna; Nowak, Marek; Berent, Katarzyna; Kania, Bogusz

2014-01-01

Highlights: • Current density of the electrodeposition affects the incorporation of Al 2 O 3 in Ni matrix. • Ni/Al 2 O 3 composite coatings exhibit changes in crystallographic texture. • The pitting corrosion effects were observed in Ni/Al 2 O 3 coatings. • Residual stresses were decreased with increasing current density and coating thickness. - Abstract: Electrodeposition process is a very promising method for producing metal matrix composites reinforced with ceramic particles. In this method insoluble particles suspended in an electrolytic bath are embedded in a growing metal layer. This paper is focused on the investigations of the nickel matrix nanocomposite coatings with hard α-Al 2 O 3 nano-particles, electrochemically deposited from modified Watts-type baths on steel substrates. The influence of various current densities on the microstructure, residual stresses, texture, hardness and corrosion resistance of the deposited nickel/alumina coatings was investigated. The surface morphology, cross sections of the coatings and distribution of the ceramic particles in the metal matrix were examined by scanning electron microscopy. The phase composition, residual stresses and preferred grain orientation of the coatings were characterized using X-ray diffraction techniques. The coating morphology revealed that α-Al 2 O 3 particles show a distinct tendency to form agglomerates, approximately uniformly distributed into the nickel matrix

Kinetics and mechanism of oxidation of carbidized electrolytic chromium coatings

International Nuclear Information System (INIS)

Arkharov, V.I.; Yar-Mukhamedov, Sh.Kh.

1978-01-01

Thermal stability carbidized electrolytic chromium coatings has been studied depending on the conditions of their formation; the specific features of the mechanism of oxidation at 1200 deg in an air atmosphere have been elucidated. It has been established that kinetics of high temperature oxidation of the coatings depends essentially on the conditions of their formation and on the composition of steel to which the coating is applied. It has been shown that two oxidation mechanisms are possible: by diffusion of the residual chromium through a carbide layer along the carbide grain boundaries outwards or, when there is no residual chromium, by chemical reaction of carbon combustion and oxidation of the liberated chromium. The comparison of oxidation kinetic curves of the samples of 38KhMYuA, 35KhGSA, and DI-22 steels with and without coating has shown that the coatings under study have a better protective effect on 38KhMYuA steel than on 35KhGSA, although without coating oxidability of the first steel is higher than that of the second

Molecular interactions of mussel protective coating protein, mcfp-1, from Mytilus californianus.

Science.gov (United States)

Lu, Qingye; Hwang, Dong Soo; Liu, Yang; Zeng, Hongbo

2012-02-01

Protective coating of the byssus of mussels (Mytilus sp.) has been suggested as a new paradigm of medical coating due to its high extensibility and hardness co-existence without their mutual detriment. The only known biomacromolecule in the extensible and tough coating on the byssus is mussel foot protein-1 (mfp-1), which is made up with positively charged residues (~20 mol%) and lack of negatively charged residues. Here, adhesion and molecular interaction mechanisms of Mytilus californianus foot protein-1 (mcfp-1) from California blue mussel were investigated using a surface forces apparatus (SFA) in buffer solutions of different ionic concentrations (0.2-0.7 M) and pHs (3.0-5.5). Strong and reversible cohesion between opposed positively charged mcfp-1 films was measured in 0.1 M sodium acetate buffer with 0.1 M KNO(3). Cohesion of mcfp-1 was gradually reduced with increasing the ionic strength, but was not changed with pH variations. Oxidation of 3,4-dihydroxyphenylalanine (DOPA) residues of mcfp-1, a key residue for adhesive and coating proteins of mussel, didn't change the cohesion strength of mcfp-1 films, but the addition of chemicals with aromatic groups (i.e., aspirin and 4-methylcatechol) increased the cohesion. These results suggest that the cohesion of mcfp-1 films is mainly mediated by cation-π interactions between the positively charged residues and benzene rings of DOPA and other aromatic amino acids (~20 mol% of total amino acids of mcfp-1), and π-π interactions between the phenyl groups in mcfp-1. The adhesion mechanism obtained for the mcfp-1 proteins provides important insight into the design and development of functional biomaterials and coatings mimicking the extensible and robust mussel cuticle coating. Copyright © 2011 Elsevier Ltd. All rights reserved.

Optical residual stress measurement in TFT-LCD panels

Science.gov (United States)

Wang, Wei-Chung; Sung, Po-Chi

2017-06-01

The residual stress of the glass substrate might be one of causes to produce the non-uniform light distribution defect, i.e. Mura, in thin film transistor-liquid crystal display (TFT-LCD) panels. Glass is a birefringent material with very low birefringence. Furthermore, the thinner and thinner thickness request from the market makes the traditional photoelasticity almost impossible to measure the residual stresses produced in thin glass plates. Recently, a low-level stress measurement method called transmissivity extremities theory of photoelasticity (TEToP) was successfully developed to measure the residual stress in glass plate. Besides, to measure the stress of the glass plate in the TFT-LCD panel whose rear surface may has different kinds of coatings, an advanced reflection photoelasticity was also developed. In this paper, three commercially available glass plates with 0.33mm nominal thickness and three glass circular disks with different coatings were inspected to verify the feasibility of the TEToP and the advanced reflection photoelasticity, respectively.

Spectral Modeling of Residual Stress and Stored Elastic Strain Energy in Thermal Barrier Coatings

Energy Technology Data Exchange (ETDEWEB)

Donegan, Sean; Rolett, Anthony

2013-12-31

Solutions to the thermoelastic problem are important for characterizing the response under temperature change of refractory systems. This work extends a spectral fast Fourier transform (FFT) technique to analyze the thermoelastic behavior of thermal barrier coatings (TBCs), with the intent of probing the local origins of failure in TBCs. The thermoelastic FFT (teFFT) approach allows for the characterization of local thermal residual stress and strain fields, which constitute the origins of failure in TBC systems. A technique based on statistical extreme value theory known as peaks-over-threshold (POT) is developed to quantify the extreme values ("hot spots") of stored elastic strain energy (i.e., elastic energy density, or EED). The resolution dependence of the teFFT method is assessed through a sensitivity study of the extreme values in EED. The sensitivity study is performed both for the local (point-by-point) eld distributions as well as the grain scale eld distributions. A convergence behavior to a particular distribution shape is demonstrated for the local elds. The grain scale fields are shown to exhibit a possible convergence to a maximum level of EED. To apply the teFFT method to TBC systems, 3D synthetic microstructures are created to approximate actual TBC microstructures. The morphology of the grains in each constituent layer as well as the texture is controlled. A variety of TBC materials, including industry standard materials and potential future materials, are analyzed using the teFFT. The resulting hot spots are quantified using the POT approach. A correlation between hot spots in EED and interface rumpling between constituent layers is demonstrated, particularly for the interface between the bond coat (BC) and the thermally grown oxide (TGO) layer.

Direct morphological comparison of vacuum plasma sprayed and detonation gun sprayed hydroxyapatite coatings for orthopaedic applications.

Science.gov (United States)

Gledhill, H C; Turner, I G; Doyle, C

1999-02-01

Hydroxyapatite coatings on titanium substrates were produced using two thermal spray techniques vacuum plasma spraying and detonation gun spraying. X-ray diffraction was used to compare crystallinity and residual stresses in the coatings. Porosity was measured using optical microscopy in conjunction with an image analysis system. Scanning electron microscopy and surface roughness measurements were used to characterise the surface morphologies of the coatings. The vacuum plasma sprayed coatings were found to have a lower residual stress, a higher crystallinity and a higher level of porosity than the detonation gun coatings. It is concluded that consideration needs to be given to the significance of such variations within the clinical context.

Study on microstructure of Al coating on beryllium substrates

International Nuclear Information System (INIS)

Li Ruiwen; Xian Xiaobin; Zou Juesheng; Zhang Pengcheng

2002-01-01

Magnetron sputtering ion plating and plasma spraying have been used to make aluminium coating on beryllium substrate. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Auger electron energy spectrum (AES) and X-ray stress analysis were used to study microstructure and interface and residual stress and diffusion content of Al coating. The results show that width of diffusion zone made by magnetron sputtering ion plating is about 1 μm, coating is composed of columnar grains and internal stress of Al coating is about zero. Coating deposited by plasma spraying is not homogeneous and there are microcracks at interface

Erosion resistance and adhesion of composite metal/ceramic coatings produced by plasma spraying

OpenAIRE

Ramm , D.; Hutchings , I.; Clyne , T.

1993-01-01

Ceramic coatings can exhibit greater erosion resistance than most metallic coatings. Such coatings are conveniently produced by thermal spraying. Unfortunately, thermally sprayed ceramic coatings often exhibit poor adhesion, partly as a consequence of the development of residual stresses during spraying and subsequent cooling. Composite coatings have been studied using aluminium/alumina deposits on steel substrates. The incorporation of ceramics within a ductile matrix has potential for sharp...

21st Century Locomotive Technology: Quarterly Technical Status Report 9 DOE/AL68284-TSR09

Energy Technology Data Exchange (ETDEWEB)

Lembit Salasoo; Paul Houpt; Jennifer Topinka; Anthony Furman

2005-06-29

Locomotive-scale single cylinder engine with common rail fuel injection data was gathered to explore the fuel consumption and particulate matter emissions entitlement. A structured experiment on thermal spray application of polymer based compressor abradables was begun. Turbine performance improvements were found due to metallic abradables coatings. Hybrid energy storage battery ripple current and long-term cycling tests have been performed. Final track test of advanced energy management system was performed. Fuel optimization computational methods have been enhanced, and a prototype real-time graphic interface developed.

Membrane-bound conformation of M13 major coat protein : a structure validation through FRET-derived constraints

NARCIS (Netherlands)

Vos, W.L.; Koehorst, R.B.M.; Spruijt, R.B.; Hemminga, M.A.

2005-01-01

M13 major coat protein, a 50-amino-acid-long protein, was incorporated into DOPC/DOPG (80/20 molar ratio) unilamellar vesicles. Over 60% of all amino acid residues was replaced with cysteine residues, and the single cysteine mutants were labeled with the fluorescent label I-AEDANS. The coat protein

Unraveling the Role of the C-terminal Helix Turn Helix of the Coat-binding Domain of Bacteriophage P22 Scaffolding Protein*

Science.gov (United States)

Padilla-Meier, G. Pauline; Gilcrease, Eddie B.; Weigele, Peter R.; Cortines, Juliana R.; Siegel, Molly; Leavitt, Justin C.; Teschke, Carolyn M.; Casjens, Sherwood R.

2012-01-01

Many viruses encode scaffolding and coat proteins that co-assemble to form procapsids, which are transient precursor structures leading to progeny virions. In bacteriophage P22, the association of scaffolding and coat proteins is mediated mainly by ionic interactions. The coat protein-binding domain of scaffolding protein is a helix turn helix structure near the C terminus with a high number of charged surface residues. Residues Arg-293 and Lys-296 are particularly important for coat protein binding. The two helices contact each other through hydrophobic side chains. In this study, substitution of the residues of the interface between the helices, and the residues in the β-turn, by aspartic acid was used examine the importance of the conformation of the domain in coat binding. These replacements strongly affected the ability of the scaffolding protein to interact with coat protein. The severity of the defect in the association of scaffolding protein to coat protein was dependent on location, with substitutions at residues in the turn and helix 2 causing the most significant effects. Substituting aspartic acid for hydrophobic interface residues dramatically perturbs the stability of the structure, but similar substitutions in the turn had much less effect on the integrity of this domain, as determined by circular dichroism. We propose that the binding of scaffolding protein to coat protein is dependent on angle of the β-turn and the orientation of the charged surface on helix 2. Surprisingly, formation of the highly complex procapsid structure depends on a relatively simple interaction. PMID:22879595

Effect of Silicon Addition on Microstructure and Mechanical Properties of Chromium and Titanium Based Coatings

Directory of Open Access Journals (Sweden)

Luis Carlos Ardila-Téllez

2014-07-01

Full Text Available The changes in the microstructure, mechanical properties and residual stresses of AlTiN, AlTiSiN, AlCrN and AlCrSiN coatings, has been studied before and after annealing at 900 ºC and 1100 ºC, using scanning and transmission electron microscopy, along with nano-indentation and X-ray diffraction techniques. The As-deposited coatings show a columnar structure, with a crystallite size between 18 nm and 28 nm. Despite the silicon addition, no effect on the crystallite size refinement was observed.However, the addition of silicon increases hardness, elastic modulus and compressive residual stresses. After annealing at 900 ºC, the crystallite size growth and the residual stress relaxes; therefore, the coating hardness decreases. At 1100 ºC, the oxide layers formed in AlTiN and AlTiSiN, which act as protective layers enhancing oxidation resistance; meanwhile, a complete oxidation of AlCrN and AlCrSiN coatings take place. The Titanium based coatings present some superior mechanical properties and oxidation resistance than the chromium based coatings at 900 ºC and 1100 ºC.

Computational Screening for Design of Optimal Coating Materials to Suppress Gas Evolution in Li-Ion Battery Cathodes.

Science.gov (United States)

Min, Kyoungmin; Seo, Seung-Woo; Choi, Byungjin; Park, Kwangjin; Cho, Eunseog

2017-05-31

Ni-rich layered oxides are attractive materials owing to their potentially high capacity for cathode applications. However, when used as cathodes in Li-ion batteries, they contain a large amount of Li residues, which degrade the electrochemical properties because they are the source of gas generation inside the battery. Here, we propose a computational approach to designing optimal coating materials that prevent gas evolution by removing residual Li from the surface of the battery cathode. To discover promising coating materials, the reactions of 16 metal phosphates (MPs) and 45 metal oxides (MOs) with the Li residues, LiOH, and Li 2 CO 3 are examined within a thermodynamic framework. A materials database is constructed according to density functional theory using a hybrid functional, and the reaction products are obtained according to the phases in thermodynamic equilibrium in the phase diagram. In addition, the gravimetric efficiency is calculated to identify coating materials that can eliminate Li residues with a minimal weight of the coating material. Overall, more MP and MO materials react with LiOH than with Li 2 CO 3 . Specifically, MPs exhibit better reactivity to both Li residues, whereas MOs react more with LiOH. The reaction products, such as Li-containing phosphates or oxides, are also obtained to identify the phases on the surface of a cathode after coating. On the basis of the Pareto-front analysis, P 2 O 5 could be an optimal material for the reaction with both Li residuals. Finally, the reactivity of the coating materials containing 3d/4d transition metal elements is better than that of materials containing other types of elements.

Interface topography and residual stress distributions in W coatings for fusion armour applications

Energy Technology Data Exchange (ETDEWEB)

Thomas, G. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)], E-mail: g.thomas@cranfield.ac.uk; Vincent, R. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Matthews, G. [UKAEA Fusion, K2 Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Dance, B. [TWI Ltd, Granta Park, Great Abingdon, Cambridge CB1 6AL (United Kingdom); Grant, P.S. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)

2008-03-25

Vacuum plasma sprayed (VPS) tungsten (W) coatings are potential plasma facing components in future fusion power plants. However, the large coefficient of thermal expansion mismatch between W and underlying structural steels and other metallic materials poses a significant problem for manufacturing and service life because of the evolution of large thermally induced stresses leading to failure. In this paper, the effects of the substrate/coating interface 3D geometry on stress distributions are investigated using finite element analysis and VPS experiments to manufacture up to 2 mm thick W coatings. The key factors that affect internal stress distributions during thermal exposure have been identified including graded composition inter-layers, stress concentration effects, mechanical adhesion, and the possible role of segmentation in relieving coating stresses on surface sculptured substrates.

Interface topography and residual stress distributions in W coatings for fusion armour applications

International Nuclear Information System (INIS)

Thomas, G.; Vincent, R.; Matthews, G.; Dance, B.; Grant, P.S.

2008-01-01

Vacuum plasma sprayed (VPS) tungsten (W) coatings are potential plasma facing components in future fusion power plants. However, the large coefficient of thermal expansion mismatch between W and underlying structural steels and other metallic materials poses a significant problem for manufacturing and service life because of the evolution of large thermally induced stresses leading to failure. In this paper, the effects of the substrate/coating interface 3D geometry on stress distributions are investigated using finite element analysis and VPS experiments to manufacture up to 2 mm thick W coatings. The key factors that affect internal stress distributions during thermal exposure have been identified including graded composition inter-layers, stress concentration effects, mechanical adhesion, and the possible role of segmentation in relieving coating stresses on surface sculptured substrates

Adhesive strength of hydroxyl apatite(HA coating and biomechanics behavior of HA-coated prosthesis:an experimental study

Directory of Open Access Journals (Sweden)

Tian-yang ZHANG

2011-05-01

Full Text Available Objective To explore the influence of adhesive strength of hydroxyapatite(HA coating on the post-implantation stability of HA-coated prosthesis.Methods The adhesive strength and biomechanics behavior of HA coating were studied by histopathological observation,material parameters and biomechanical testing,the titanium(Ti-coated prosthesis was employed as control.Results Scratch test showed that the adhesive strength of HA coating was significantly lower than that of Ti coating(P < 0.01.Histopathological examination and bone morphometry showed that,at the early stage of prosthesis implantation,the bony growth around HA-coated prosthesis was significantly higher than that around Ti-coated prosthesis(P < 0.01,but the ultimate shear strength of HA-coated prosthesis was much lower than that of Ti-coated prosthesis(P < 0.01.After the push-out test with prosthesis,histopathological observation showed that there were accumulations of clump-and strip-like granular residues on the surface of bones that newly grew around the HA-coated prosthesis,and surface energy-dispersive X-ray spectroscopy(EDX analysis also confirmed that the shear stress induced HA decohesion from the substrate of prosthesis.Conclusions Although HA coating showed a satisfactory effect on early bone formation and prosthetic stability,due to the deficiencies of adhesive strength,the early stability of prosthesis may be gradually destroyed by the shear loads of human body and coating degradation.

Gas-thermal coating of powdered materials. Communication 2

International Nuclear Information System (INIS)

Ermakov, S.S.

1986-01-01

This paper investigates the microstructure, microhardness, chemical composition of the transition zone, and also the strength characteristics of gas-thermal coatings including their adhesive power to the substrate (iron brand NC 100.24) and the residual stresses in the coatings. The microstructure of the transition zone was investigated; it was established that on the side of the substrate its density is greater than the mean density of both types of coating. It is shown that the porosity of the substrate has a competing effect on the thermal interaction of materials. Discovered regularities lead to the conclusion that the process of gas-thermal coating of powdered materials is more effective than when compact materials are coated; most effective is the combination of gas-thermal coating with processes of heat treatment of powder-metallurgy products

KEY INTERACTIONS FOR CLATHRIN COAT STABILITY

Science.gov (United States)

Böcking, Till; Aguet, Francois; Rapoport, Iris; Banzhaf, Manuel; Yu, Anan; Zeeh, Jean Christophe; Kirchhausen, Tom

2014-01-01

SUMMARY Clathrin-coated vesicles are major carriers of vesicular traffic in eukaryotic cells. This endocytic pathway relies on cycles of clathrin coat assembly and Hsc70-mediated disassembly. Here we identify histidine residues as major determinants of lattice assembly and stability. They are located at the invariant interface between the proximal and distal segments of clathrin heavy chains, in triskelions centered on two adjacent vertices of the coated-vesicle lattice. Mutation of these histidine to glutamine alters the pH dependence of coat stability. We then describe single-particle fluorescence imaging experiments in which we follow the effect of these histidine mutations on susceptibility to Hsc70-dependent uncoating. Coats destabilized by these mutations require fewer Hsc70 molecules to initiate disassembly as predicted by a model in which Hsc70 traps conformational distortions during the auxilin- and Hsc70:ATP-mediated uncoating reaction. PMID:24815030

Phase evolution and thermal properties of yttria-stabilized hafnia nano-coatings deposited on alumina

Science.gov (United States)

Rubio, Ernesto Javier

High-temperature coatings are critical to the future power-generation systems and industries. Thermal barrier coatings (TBCs), which are usually the ceramic materials applied as thin coatings, protect engine components and allow further increase in engine temperatures for higher efficiency. Thus, the durability and reliability of the coating systems have to be more robust compared to current natural gas based engines. While a near and mid-term target is to develop TBC architecture with a 1300 °C surface temperature tolerance, a deeper understanding of the structure evolution and thermal behavior of the TBC-bond coat interface, specifically the thermally grown oxide (TGO), is of primary importance. In the present work, attention is directed towards yttria-stabilized hafnia (YSH) coatings on alumina (α-Al2O 3) to simulate the TBC-TGO interface and understand the phase evolution, microstructure and thermal oxidation of the coatings. YSH coatings were grown on α-Al2O3 substrates by sputter deposition by varying coating thickness in a wide range ˜30-1000 nm. The effect of coating thickness on the structure, morphology and the residual stress has been investigated using X-ray diffraction (XRD) and high resolution scanning electron microscopy (SEM). Thermal oxidation behavior of the coatings has been evaluated using the isothermal oxidation measurements under static conditions. X-ray diffraction analyses revealed the existence of monoclinic hafnia phase for relatively thin coatings indicating that the interfacial phenomena are dominant in phase stabilization. The evolution towards pure stabilized cubic phase of hafnia with the increasing coating thickness is observed. The SEM results indicate the changes in morphology of the coatings; the average grain size increases from 15 to 500 nm with increasing thickness. Residual stress was calculated employing XRD using the variable ψ-angle. Relation between residual stress and structural change is also studied. The results

Processing-structure-property relationships in electron beam physical vapor deposited yttria stabilized zirconia coatings

International Nuclear Information System (INIS)

Rao, D. Srinivasa; Valleti, Krishna; Joshi, S. V.; Janardhan, G. Ranga

2011-01-01

The physical and mechanical properties of yttria stabilized zirconia (YSZ) coatings deposited by the electron beam physical vapor deposition technique have been investigated by varying the key process variables such as vapor incidence angle and sample rotation speed. The tetragonal zirconia coatings formed under varying process conditions employed were found to have widely different surface and cross-sectional morphologies. The porosity, phase composition, planar orientation, hardness, adhesion, and surface residual stresses in the coated specimens were comprehensively evaluated to develop a correlation with the process variables. Under transverse scratch test conditions, the YSZ coatings exhibited two different crack formation modes, depending on the magnitude of residual stress. The influence of processing conditions on the coating deposition rate, column orientation angle, and adhesion strength has been established. Key relationships between porosity, hardness, and adhesion are also presented.

Mechanical integrity of thin inorganic coatings on polymer substrates under quasi-static, thermal and fatigue loadings

International Nuclear Information System (INIS)

Leterrier, Y.; Mottet, A.; Bouquet, N.; Gillieron, D.; Dumont, P.; Pinyol, A.; Lalande, L.; Waller, J.H.; Manson, J.-A.E.

2010-01-01

The interplay between residual stress state, cohesive and adhesive properties of coatings on substrates is reviewed in this article. Attention is paid to thin inorganic coatings on polymers, characterized by a very high hygro-thermo-mechanical contrast between the brittle and stiff coating and the compliant and soft substrate. An approach to determine the intrinsic, thermal and hygroscopic contributions to the coating residual stress is detailed. The critical strain for coating failure, coating toughness and coating/substrate interface shear strength are derived from the analysis of progressive coating cracking under strain. Electro-fragmentation and electro-fatigue tests in situ in a microscope are described. These methods enable reproducing the thermo-mechanical loads present during processing and service life, hence identifying and modeling the critical conditions for failure. Several case studies relevant to food and pharmaceutical packaging, flexible electronics and thin film photovoltaic devices are discussed to illustrate the benefits and limits of the present methods and models.

Electroless Plated Nanodiamond Coating for Stainless Steel Passivation

International Nuclear Information System (INIS)

Li, D.; Korinko, P.; Spencer, W.; Stein, E.

2016-01-01

Tritium gas sample bottles and manifold components require passivation surface treatments to minimize the interaction of the hydrogen isotopes with surface contamination on the stainless steel containment materials. This document summarizes the effort to evaluate electroless plated nanodiamond coatings as a passivation layer for stainless steel. In this work, we developed an electroless nanodiamond (ND)-copper (Cu) coating process to deposit ND on stainless steel parts with the diamond loadings of 0%, 25% and 50% v/v in a Cu matrix. The coated Conflat Flanged Vessel Assemblies (CFVAs) were evaluated on surface morphology, composition, ND distribution, residual hydrogen release, and surface reactivity with deuterium. For as-received Cu and ND-Cu coated CFVAs, hydrogen off-gassing is rapid, and the off-gas rates of H 2 was one to two orders of magnitude higher than that for both untreated and electropolished stainless steel CFVAs, and hydrogen and deuterium reacted to form HD as well. These results indicated that residual H 2 was entrapped in the Cu and ND-Cu coated CFVAs during the coating process, and moisture was adsorbed on the surface, and ND and/or Cu might facilitate catalytic isotope exchange reaction for HD formation. However, hydrocarbons (i.e., CH 3 ) did not form, and did not appear to be an issue for the Cu and ND-Cu coated CFVAs. After vacuum heating, residual H 2 and adsorbed H 2 O in the Cu and ND-Cu coated CFVAs were dramatically reduced. The H 2 off-gassing rate after the vacuum treatment of Cu and 50% ND-Cu coated CFVAs was on the level of 10 -14 l mbar/s cm 2 , while H 2 O off-gas rate was on the level of 10 -15 l mbar/s cm 2 , consistent with the untreated or electropolished stainless steel CFVA, but the HD formation remained. The Restek EP bottle was used as a reference for this work. The Restek Electro-Polished (EP) bottle and their SilTek coated bottles tested under a different research project exhibited very little hydrogen off-gassing and

Electroforming of nickel and partially stabilized zirconia (Ni+PSZ) gradient coating

Energy Technology Data Exchange (ETDEWEB)

Li Jun [Herbin Inst. of Technol. (China). Dept. of Appl. Chem.; Dai Changsong [Herbin Inst. of Technol. (China). Dept. of Appl. Chem.; Wang Dianlong [Herbin Inst. of Technol. (China). Dept. of Appl. Chem.; Hu Xinguo [Herbin Inst. of Technol. (China). Dept. of Appl. Chem.

1997-05-01

A sediment electrodeposition technique has been successfully used to prepare Ni+PSZ gradient coatings with a compositional gradient. The microstructure and composition of the coating have been studied by scanning electron microscopy and electron probe microanalysis. The variation of the hardness, elastic modulus, residual stress, thermal expansion coefficient and thermal conductivity of the coatings with various components is also discussed. Thermal fatigue tests demonstrate that Ni+PSZ gradient coatings improve the resistance to thermal shock by eliminating the mismatch with the substrate. (orig.)

Insect Residue Contamination on Wing Leading Edge Surfaces: A Materials Investigation for Mitigation

Science.gov (United States)

Lorenzi, Tyler M.; Wohl, Christopher J.; Penner, Ronald K.; Smith, Joseph G.; Siochi, Emilie J.

2011-01-01

Flight tests have shown that residue from insect strikes on aircraft wing leading edge surfaces may induce localized transition of laminar to turbulent flow. The highest density of insect populations have been observed between ground level and 153 m during light winds (2.6 -- 5.1 m/s), high humidity, and temperatures from 21 -- 29 C. At a critical residue height, dependent on the airfoil and Reynolds number, boundary layer transition from laminar to turbulent results in increased drag and fuel consumption. Although this represents a minimal increase in fuel burn for conventional transport aircraft, future aircraft designs will rely on maintaining laminar flow across a larger portion of wing surfaces to reduce fuel burn during cruise. Thus, insect residue adhesion mitigation is most critical during takeoff and initial climb to maintain laminar flow in fuel-efficient aircraft configurations. Several exterior treatments investigated to mitigate insect residue buildup (e.g., paper, scrapers, surfactants, flexible surfaces) have shown potential; however, implementation has proven to be impractical. Current research is focused on evaluation of wing leading edge surface coatings that may reduce insect residue adhesion. Initial work under NASA's Environmentally Responsible Aviation Program focused on evaluation of several commercially available products (commercial off-the-shelf, COTS), polymers, and substituted alkoxy silanes that were applied to aluminum (Al) substrates. Surface energies of these coatings were determined from contact angle data and were correlated to residual insect excrescence on coated aluminum substrates using a custom-built "bug gun." Quantification of insect excrescence surface coverage was evaluated by a series of digital photographic image processing techniques.

Investigation of interactions between dendrimer-coated magnetite nanoparticles and bovine serum albumin

International Nuclear Information System (INIS)

Pan Bifeng; Gao Feng; Ao Limei

2005-01-01

We investigated the interactions between dendrimer-coated magnetite nanoparticles (MNPs) and the protein serum albumin. The investigation was based on the fluorescence quenching of tryptophan residue of serum albumin after binding with the dendrimer-coated magnetite nanoparticles. The extent of the interactions between bovine serum albumin and dendrimer-coated MNPs strongly depends on their surface groups and pH value

Microstructure, composition and performance of PVD coatings designed for successful dry high speed milling

International Nuclear Information System (INIS)

Muenz, W.-D.; Lembke, M.I.; Lewis, D.B.; Smith, I.J.

2001-01-01

Dry high speed machining (HSM), particularly dry high speed milling, demands hard coatings, which exhibit high toughness, high oxidation resistance, a limited amount of residual stress and excellent adhesion to the cemented carbide (CC) substrate. These requirements are met by TiAICrYN coatings grown by the combined cathodic arc/unbalanced magnetron deposition method. Fully sufficient adhesion is achieved by ion implantation of Cr into the CC prior deposition. Residual stress is controlled by an Y - free base layer; high oxidation resistance is provided by an Y - containing 3 μm thick hard coating with 29 GPa hardness and a residual stress well below -7 GPa. Under the influence of temperatures above 800 o C, Y segregates along the columns of TiAIN and plugs the in/out diffusion of elements. A top layer of Y - containing oxynitride reduces the friction against the work piece material (0.9 to 0.65). Cutting tools coated as such may be used for dry milling up to 25 k rpm in steels HRC > 60. (author)

Industrial Market Research Report: Feasibility of commercialization of the advanced antifouling coating of Copperlok, Inc.

Energy Technology Data Exchange (ETDEWEB)

Gormley, G.J.

1990-10-01

The Copperlok antifouling process was designed to prevent marine growth on surfaces exposed to sea water. It is a method of bonding thermally sprayed Cu and Cu alloys onto an epoxy material containing microballoons (hollow spheres). After the epoxy cures, the surface is abraded so that the microballoons are fractured, exposing microscopic concave porosity. The sprayed material is directed to the surface, where it impregnates the pores, bridges and then welds across the surface, creating a very thin laminate of the metal materials security bonded to the bond coat and to the substrate. The Copperlok process laminates an approximate layer of Cu-Ni alloy 8 mils thick with an expected active life of 15--20 y. This report addresses the perceived acceptability of the process in several different marketplaces with the hope of directing the invention to the most receptive consumer group. The opinion surveys of the recreational marine industry were limited to the three coastal areas of the Atlantic, Gulf, and Pacific.

Industrial Market Research Report: Feasibility of commercialization of the advanced antifouling coating of Copperlok, Inc

Energy Technology Data Exchange (ETDEWEB)

Gormley, G.J.

1990-10-01

The Copperlok antifouling process was designed to prevent marine growth on surfaces exposed to sea water. It is a method of bonding thermally sprayed Cu and Cu alloys onto an epoxy material containing microballoons (hollow spheres). After the epoxy cures, the surface is abraded so that the microballoons are fractured, exposing microscopic concave porosity. The sprayed material is directed to the surface, where it impregnates the pores, bridges and then welds across the surface, creating a very thin laminate of the metal materials security bonded to the bond coat and to the substrate. The Copperlok process laminates an approximate layer of Cu-Ni alloy 8 mils thick with an expected active life of 15--20 y. This report addresses the perceived acceptability of the process in several different marketplaces with the hope of directing the invention to the most receptive consumer group. The opinion surveys of the recreational marine industry were limited to the three coastal areas of the Atlantic, Gulf, and Pacific.

Highly specific salt bridges govern bacteriophage P22 icosahedral capsid assembly: identification of the site in coat protein responsible for interaction with scaffolding protein.

Science.gov (United States)

Cortines, Juliana R; Motwani, Tina; Vyas, Aashay A; Teschke, Carolyn M

2014-05-01

Icosahedral virus assembly requires a series of concerted and highly specific protein-protein interactions to produce a proper capsid. In bacteriophage P22, only coat protein (gp5) and scaffolding protein (gp8) are needed to assemble a procapsid-like particle, both in vivo and in vitro. In scaffolding protein's coat binding domain, residue R293 is required for procapsid assembly, while residue K296 is important but not essential. Here, we investigate the interaction of scaffolding protein with acidic residues in the N-arm of coat protein, since this interaction has been shown to be electrostatic. Through site-directed mutagenesis of genes 5 and 8, we show that changing coat protein N-arm residue 14 from aspartic acid to alanine causes a lethal phenotype. Coat protein residue D14 is shown by cross-linking to interact with scaffolding protein residue R293 and, thus, is intimately involved in proper procapsid assembly. To a lesser extent, coat protein N-arm residue E18 is also implicated in the interaction with scaffolding protein and is involved in capsid size determination, since a cysteine mutation at this site generated petite capsids. The final acidic residue in the N-arm that was tested, E15, is shown to only weakly interact with scaffolding protein's coat binding domain. This work supports growing evidence that surface charge density may be the driving force of virus capsid protein interactions. Bacteriophage P22 infects Salmonella enterica serovar Typhimurium and is a model for icosahedral viral capsid assembly. In this system, coat protein interacts with an internal scaffolding protein, triggering the assembly of an intermediate called a procapsid. Previously, we determined that there is a single amino acid in scaffolding protein required for P22 procapsid assembly, although others modulate affinity. Here, we identify partners in coat protein. We show experimentally that relatively weak interactions between coat and scaffolding proteins are capable of driving

Applications of bauxite residue: A mini-review.

Science.gov (United States)

Verma, Ajay S; Suri, Narendra M; Kant, Suman

2017-10-01

Bauxite residue is the waste generated during alumina production by Bayer's process. The amount of bauxite residue (40-50 wt%) generated depends on the quality of bauxite ore used for the processing. High alkalinity and high caustic content in bauxite residue causes environmental risk for fertile soil and ground water contamination. The caustic (NaOH) content in bauxite residue leads to human health risks, like dermal problems and irritation to eyes. Moreover, disposal of bauxite residue requires a large area; such problems can only be minimised by utilising bauxite residue effectively. For two decades, bauxite residue has been used as a binder in cement industries and filler/reinforcement for composite materials in the automobile industry. Valuable metals and oxides, like alumina (Al 2 O 3 ), titanium oxide (TiO 2 ) and iron oxide Fe 2 O 3 , were extracted from bauxite residue to reduce waste. Bauxite residue was utilised in construction and structure industries to make geopolymers. It was also used in the making of glass-ceramics and a coating material. Recently bauxite residue has been utilised to extract rare earth elements like scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), neodymium (Nd) and dysprosium (Dy). In this review article, the mineralogical characteristics of bauxite residue are summarised and current progresses on utilisation of bauxite residue in different fields of science and engineering are presented in detail.

Electroless Plated Nanodiamond Coating for Stainless Steel Passivation

Energy Technology Data Exchange (ETDEWEB)

Li, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Korinko, P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Spencer, W. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Stein, E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2016-09-15

Tritium gas sample bottles and manifold components require passivation surface treatments to minimize the interaction of the hydrogen isotopes with surface contamination on the stainless steel containment materials. This document summarizes the effort to evaluate electroless plated nanodiamond coatings as a passivation layer for stainless steel. In this work, we developed an electroless nanodiamond (ND)-copper (Cu) coating process to deposit ND on stainless steel parts with the diamond loadings of 0%, 25% and 50% v/v in a Cu matrix. The coated Conflat Flanged Vessel Assemblies (CFVAs) were evaluated on surface morphology, composition, ND distribution, residual hydrogen release, and surface reactivity with deuterium. For as-received Cu and ND-Cu coated CFVAs, hydrogen off-gassing is rapid, and the off-gas rates of H₂ was one to two orders of magnitude higher than that for both untreated and electropolished stainless steel CFVAs, and hydrogen and deuterium reacted to form HD as well. These results indicated that residual H₂ was entrapped in the Cu and ND-Cu coated CFVAs during the coating process, and moisture was adsorbed on the surface, and ND and/or Cu might facilitate catalytic isotope exchange reaction for HD formation. However, hydrocarbons (i.e., CH₃) did not form, and did not appear to be an issue for the Cu and ND-Cu coated CFVAs. After vacuum heating, residual H₂ and adsorbed H₂O in the Cu and ND-Cu coated CFVAs were dramatically reduced. The H₂ off-gassing rate after the vacuum treatment of Cu and 50% ND-Cu coated CFVAs was on the level of 10^-14 l mbar/s cm², while H₂O off-gas rate was on the level of 10^-15 l mbar/s cm², consistent with the untreated or electropolished stainless steel CFVA, but the HD formation remained. The Restek EP bottle was used as a reference for this work. The Restek Electro-Polished (EP) bottle and their Sil

Surface protection of austenitic steels by carbon nanotube coatings

Science.gov (United States)

MacLucas, T.; Schütz, S.; Suarez, S.; Mücklich, F.

2018-03-01

In the present study, surface protection properties of multiwall carbon nanotubes (CNTs) deposited on polished austenitic stainless steel are evaluated. Electrophoretic deposition is used as a coating technique. Contact angle measurements reveal hydrophilic as well as hydrophobic wetting characteristics of the carbon nanotube coating depending on the additive used for the deposition. Tribological properties of carbon nanotube coatings on steel substrate are determined with a ball-on-disc tribometer. Effective lubrication can be achieved by adding magnesium nitrate as an additive due to the formation of a holding layer detaining CNTs in the contact area. Furthermore, wear track analysis reveals minimal wear on the coated substrate as well as carbon residues providing lubrication. Energy dispersive x-ray spectroscopy is used to qualitatively analyse the elemental composition of the coating and the underlying substrate. The results explain the observed wetting characteristics of each coating. Finally, merely minimal oxidation is detected on the CNT-coated substrate as opposed to the uncoated sample.

Finite element analysis of residual stress in plasma-sprayed ceramic

International Nuclear Information System (INIS)

Mullen, R.L.; Hendricks, R.C.; McDonald, G.

1985-01-01

Residual stress in a ZrO 2 -Y 2 O 3 ceramic coating resulting from the plasma spraying operation is calculated. The calculations were done using the finite element method. Both thermal and mechanical analysis were performed. The resulting residual stress field was compared to the measurements obtained by Hendricks and McDonald. Reasonable agreement between the predicted and measured moment occurred. However, the resulting stress field is not in pure bending

Computational homogenisation for thermoviscoplasticity: application to thermally sprayed coatings

Science.gov (United States)

Berthelsen, Rolf; Denzer, Ralf; Oppermann, Philip; Menzel, Andreas

2017-11-01

Metal forming processes require wear-resistant tool surfaces in order to ensure a long life cycle of the expensive tools together with a constant high quality of the produced components. Thermal spraying is a relatively widely applied coating technique for the deposit of wear protection coatings. During these coating processes, heterogeneous coatings are deployed at high temperatures followed by quenching where residual stresses occur which strongly influence the performance of the coated tools. The objective of this article is to discuss and apply a thermo-mechanically coupled simulation framework which captures the heterogeneity of the deposited coating material. Therefore, a two-scale finite element framework for the solution of nonlinear thermo-mechanically coupled problems is elaborated and applied to the simulation of thermoviscoplastic material behaviour including nonlinear thermal softening in a geometrically linearised setting. The finite element framework and material model is demonstrated by means of numerical examples.

Powder ink coatings in nuclear medicine and nuclear technology

International Nuclear Information System (INIS)

Kunze, S.; Schlautek, H.

1996-01-01

Powder ink coatings are being used more and more frequently to protect the surfaces of movable objects of metal, such as machines, equipment, furniture, shelves, because this solvent-free coating technique, which produces almost no residues, helps to keep the environment clean. The white and grey baking coatings so far tested for decontaminability are presented in the article. Powder ink coatings of different shades and with different binders were tested for their ability to meet future standards. All systems under examination demonstrated excellent decontaminability before and after gamma exposure to 0.3 MGy. The same performance was obtained also after exposure to 3 MGy (ten times the level required for coatings in nuclear installations according to DIN 55991 Part 1), with the exception of one polyester metallic coating. After having been exposed to chemicals and decontamination solutions, all specimens showed only permissible discoloration. (orig.) [de

Quantitation of Surface Coating on Nanoparticles Using Thermogravimetric Analysis.

Science.gov (United States)

Dongargaonkar, Alpana A; Clogston, Jeffrey D

2018-01-01

Nanoparticles are critical components in nanomedicine and nanotherapeutic applications. Some nanoparticles, such as metallic nanoparticles, consist of a surface coating or surface modification to aid in its dispersion and stability. This surface coating may affect the behavior of nanoparticles in a biological environment, thus it is important to measure. Thermogravimetric analysis (TGA) can be used to determine the amount of coating on the surface of the nanoparticle. TGA experiments run under inert atmosphere can also be used to determine residual metal content present in the sample. In this chapter, the TGA technique and experimental method are described.

Enhanced corrosion protective PANI-PAA/PEI multilayer composite coatings for 316SS by spin coating technique

Energy Technology Data Exchange (ETDEWEB)

Syed, Junaid Ali; Lu, Hongbin; Tang, Shaochun; Meng, Xiangkang, E-mail: mengxk@nju.edu.cn

2015-01-15

Highlights: • PANI-PAA/PEI multilayers with controllable thickness were fabricated by spin assembly. • PAA matrix results in the homogeneous dispersion of PANI in the composite coatings. • Spin coating combined with heating assures the linear increase in thickness with n. • The corrosion protection property of PANI-PAA/PEI coatings were optimized at n = 20. • Enhanced protection owing to multilayer structure that lengthens the diffusion pathway of ions. - Abstract: In the present study, polyaniline-polyacrylic acid/polyethyleneimine (PANI-PAA/PEI) composite coatings with a multilayer structure for corrosion protection of 316 stainless steels (316SS) were prepared by an alternate deposition. Spin coating combined with heating assists removal of residual water that result in a linear increase in thickness with layer number (n). The combination of PANI-PAA composite with PEI and their multilayer structure provides a synergistic enhancement of corrosion resistance properties as determined by electrochemical measurements in 3.5% NaCl solution. Importantly, the PANI-PAA/PEI coating with an optimized layer number of n = 20 shows improved corrosion protection. The superior performance was attributed to the formation of an interfacial oxide layer as well as the multilayer structure that extend the diffusion pathway of corrosive ions.

Effects of Laser Re-melting on the Corrosion Properties of HVOF Coatings

Science.gov (United States)

Yilbas, B. S.; Toor, I. H.; Patel, F.; Baig, M. A.

2013-05-01

HVOF coating of Inconel 625 powder on carbon steel is carried out. Laser melting of the resulting coating is realized to improve coating structural integrity. Morphological and microstructural changes are examined in the coating prior and after laser treatment process using scanning electron microscopy, energy dispersive spectroscopy, and x-ray diffraction (XRD). The residual stress developed is measured on the surface vicinity of the laser-treated coating using the XRD technique. The corrosion resistance of the laser-treated and untreated coating surfaces is measured, incorporating the potentiodynamic tests in 0.5 M NaCl aqueous solution. It is found that laser treatment reduces the pores and produces cellular structures with different sizes and orientations in the coating. Laser-controlled melting improves the corrosion resistance of the coating surface.

Bond Stability of a Universal Adhesive System to Eroded/Abraded Dentin After Deproteinization.

Science.gov (United States)

Augusto, M G; Torres, Crg; Pucci, C R; Schlueter, N; Borges, A B

Erosive/abrasive challenges can potentially compromise bonding to dentin. Aiming to improve the quality and stability of bonding to this substrate, this study investigated the combined effect of erosion and toothbrush abrasion on the microtensile bond strength (μTBS) stability to dentin using a universal adhesive system in total and self-etching modes, associated or not associated with deproteinization. Bovine dentin specimens were divided into five groups according to the organic matrix condition (n=20): control (C); erosion (E); erosion + abrasion (EA); erosion + sodium hypochlorite (EH); erosion + abrasion + sodium hypochlorite (EAH). The groups were further divided (n=10) according to the mode of application (total or self-etching) of a universal adhesive. After the bonding procedure, composite blocks were built up, and the samples were cut to obtain sticks for μTBS testing. For each specimen, one-half of the sticks was immediately tested, and the other one-half was tested after artificial aging (5000 thermocycles, 5°C and 55°C). Three-way analysis of variance (α=5%) showed a significant difference for the triple interaction ( p=0.0007). Higher μTBS means were obtained for the EH and EAH groups compared with the E and EA groups. The control group showed immediate μTBS values similar to that of the E and EA groups for both bond strategies. Erosion and erosion/abrasion did not significantly influence the immediate μTBS to dentin. Artificial aging reduced μTBS values for the groups C, E, and EA using the total-etching mode. Deproteinization maintained the bond stability to artificially aged eroded and eroded/abraded dentin.

40 CFR 174.512 - Coat Protein of Potato Virus Y; exemption from the requirement of a tolerance.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Coat Protein of Potato Virus Y...-INCORPORATED PROTECTANTS Tolerances and Tolerance Exemptions § 174.512 Coat Protein of Potato Virus Y; exemption from the requirement of a tolerance. Residues of Coat Protein of Potato Virus Y are exempt from...

Comparison of different types of coatings in headspace solid phase micro extraction for the analysis of pesticide residues in vegetables and fruits

International Nuclear Information System (INIS)

Chai, Mee Kin; Tan, Guan Huat

2008-01-01

Despite the continuing development of solid-phase micro extraction (SPME) fiber coatings, their selection presents some difficulties for analytes in choosing the appropriate fiber for a particular application. There are many types of SPME coatings available commercially. The most widely used for determination of pesticide residues in vegetable and fruits are polydimethylsiloxane (PDMS) and polyacrylate (PA). A headspace solid phase micro extraction (HS-SPME) procedure using these two commercialized fibers (PDMS and PA) is presented for the determination of selected groups of organo chlorine and organophosphorus pesticides. The extraction performances of these compounds were compared using these two fibers. The optimal experimental procedures for the adsorption and desorption of pesticides were determined. An explanation for the extraction differences is suggested based on the different thickness, polarity of the polymeric film of fibers and the different extracting matrices. In addition, the higher detector response of the pesticides after addition of aliquots of water and an organic solvent to the vegetable and fruit samples are also discussed. The SPME fibers were reusable until a maximum of 120 extractions. Finally, the optimized procedures were applied successfully for the determination of these compounds in vegetable and fruits samples. Mean recoveries for all pesticides were between 75.0-97 % with RSD below 7 %. (author)

Induction surface hardening of hard coated steels

Energy Technology Data Exchange (ETDEWEB)

Pantleon, K.; Kessler, O.; Hoffann, F.; Mayr, P. [Stiftung Inst. fuer Werkstofftechnik, Bremen (Germany)

1999-11-01

The properties of hard coatings deposited using CVD processes are usually excellent. However, high deposition temperatures negatively influence the substrate properties, especially in the case of low alloyed steels. Therefore, a subsequent heat treatment is necessary to restore the properties of steel substrates. Here, induction surface hardening is used as a method of heat treatment after the deposition of TiN hard coatings on AISI 4140 (DIN42CrMo4) substrates. The influences of the heat treatment on both the coating and the substrate properties are discussed in relation to the parameters of induction heating. Thereby, the heating time, heating atmosphere and the power input into the coating-substrate compounds are varied. As a result of induction surface hardening, the properties of the substrates are improved without losing good coating properties. High hardness values in the substrate near the interface allow the AISI 4140 substrates to support TiN hard coatings very well. Consequently, higher critical loads are measured in scratch tests after the heat treatment. Also, compressive residual stresses in the substrate are generated. In addition, only a very low distortion appears. (orig.)

Mechanical stability and adhesion of ceramic coatings deposited on steels

International Nuclear Information System (INIS)

Ignat, M.; Armann, A.; Moberg, L.; Sibieude, F.

1991-01-01

This paper presents the results of two sorts of deformation experiment performed on coating/substrate systems. The coating/substrate systems were constituted by coatings of titanium nitride and chromium carbide, deposited in both cases on steel substrates. The formation experiments were cyclic bending tests on macroscopic samples with chromium carbide coatings, and straining experiments performed in a scanning electron microscope on samples with titanium nitride coatings. By the analysis of our experimental results we develop an attempt to correlate the mechanical stability of the systems with the interfacial adhesion, by taking into account the internal residual stresses as an adhesion parameter. For the samples with chromium carbide coatings, the evolution of internal stresses is detected from X-ray diffractometry and discussed in terms of the observed induced damaging mechanisms, in the cyclic tests. For the samples with titanium nitride coatings, we discussed the adhesion from the microstructural observations and from the critical parameters determined during the in-situ straining experiments. (orig.)

Residual Stress Analysis for Engineering Applications by Means of Neutron Diffraction

International Nuclear Information System (INIS)

Gndupel-Herold, Thomas; Brand, Paul C.; Prask, Henry J.

1999-01-01

The economic and scientific importance of neutron diffraction residual stress analysis has led to an increasing number of suitable instruments worldwide. Recently, a dedicated state-of-the-art diffractometer has been installed at the National Institute of Standards and Technology reactor. It has been used for a variety of measurements on basic and engineering stress problems. Among the most prominent examples that have been investigated are residual stresses in rails, weldments, and plasma-sprayed coatings

40 CFR 174.531 - Coat protein of plum pox virus; exemption from the requirement of a tolerance.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Coat protein of plum pox virus...-INCORPORATED PROTECTANTS Tolerances and Tolerance Exemptions § 174.531 Coat protein of plum pox virus; exemption from the requirement of a tolerance. Residues of the coat protein of plum pox virus in or on the...

"Combined Occlusion and Atropine Therapy" Versus "Augmented Part-Time Patching" in Children with Refractory/Residual Amblyopia: A Pilot Study.

Science.gov (United States)

Sachdeva, Virender; Mittal, Vaibhev; Gupta, Varun; Gunturu, Rekha; Kekunnaya, Ramesh; Chandrasekharan, Anjali; Chabblani, Preeti Patil; Rao, Harsha L

2016-01-01

To compare the efficacy of combined occlusion and atropine therapy (COAT) and augmented part-time patching for the treatment of unilateral refractory/residual amblyopia. This retrospective study evaluated children between 4 and 11 years with refractory/residual amblyopia who were treated with either additional atropine (COAT group) or increased hours of patching (augmented group). Data were collected on improvement in best-corrected visual acuity (BCVA; logarithm of the minimum angle of resolution [logMAR] units) at each follow-up visit. There were 19 children in the COAT group and 17 children in the augmented group. The baseline BCVA of the amblyopic eye was 0.79 ± 0.36 logMAR in the COAT group and 0.72 ± 0.26 logMAR in augmented group. Children were statistically significantly younger in the COAT group (6.4 ± 2.2 years) compared to the augmented group (8.6 ± 3.3 years, P = 0.02). The mean duration of follow-up was statistically significantly longer in the augmented group (20.2 COAT group; 13.9 months augmented group) (P = 0.03). Compliance was similar in both groups. LogMAR BCVA (adjusted for difference in age and baseline BCVA) was statistically significantly better in the COAT group (0.56 ± 0.04) compared to the augmented group (0.80 ± 0.04) at 3 months (P = 0.000); 6 months (COAT group, 0.50 ± 0.04 vs. augmented group, 0.74 ± 0.04; P = 0.04) and at 1 year (COAT group, 0.42 ± 0.04 vs. augmented group, 0.67 ± 0.04, P = 0.000). There was statistically significantly greater improvement in logMAR BCVA at 6 months in COAT group (0.26 ± 0.15) compared to the augmented group (0.02 ± 0.14), (P = 0.0002). Age, gender, pretreatment BCVA, duration of follow-up, or compliance to patching did not affect improvement in BCVA. COAT may result in greater improvement in BCVA than augmented part-time patching in children with unilateral residual/refractory amblyopia.

Microstructure and Properties of Ni and Ni/Al2O3 Coatings Electrodeposited at Various Current Densities

Directory of Open Access Journals (Sweden)

Góral A.

2016-03-01

Full Text Available The study presents investigations of an influence of various direct current densities on microstructure, residual stresses, texture, microhardness and corrosion resistance of the nickel coatings electrodeposited from modified Watt’s baths. The properties of obtained coatings were compared to the nano-crystalline composite Ni/Al2O3 coatings prepared under the same plating conditions. The similarities and differences of the obtained coatings microstructures visible on both their surfaces and cross sections and determined properties were presented. The differences in the growth character of the Ni matrix and in the microstructural properties were observed. All electrodeposited Ni and Ni/Al2O3 coatings were compact and well adhering to the steel substrates. The thickness and the microhardness of the Ni and Ni/Al2O3 deposits increased significantly with the current density in the range 2 - 6 A/dm2. Residual stresses are tensile and they reduced as the current density increased. The composite coatings revealed better protection from the corrosion of steel substrate than pure nickel in solution 1 M NaCl.

Effect of solder flux residue on the performance of silicone conformal coatings on printed circuit board assemblies

DEFF Research Database (Denmark)

Rathinavelu, Umadevi; Jellesen, Morten Stendahl; Ambat, Rajan

2013-01-01

Conformal coatings are applied on printed circuit board assemblies (PCBAs) in order to protect the assembly from environmental influence and silicone-based coating is commonly used. A systematic study on the performance of silicone conformal coating in connection with process-related contaminants...

Growth, microstructure, and field-emission properties of synthesized diamond film on adamantane-coated silicon substrate by microwave plasma chemical vapor deposition

International Nuclear Information System (INIS)

Tiwari, Rajanish N.; Chang Li

2010-01-01

Diamond nucleation on unscratched Si surface is great importance for its growth, and detailed understanding of this process is therefore desired for many applications. The pretreatment of the substrate surface may influence the initial growth period. In this study, diamond films have been synthesized on adamantane-coated crystalline silicon {100} substrate by microwave plasma chemical vapor deposition from a gaseous mixture of methane and hydrogen gases without the application of a bias voltage to the substrates. Prior to adamantane coating, the Si substrates were not pretreated such as abraded/scratched. The substrate temperature was ∼530 deg. C during diamond deposition. The deposited films are characterized by scanning electron microscopy, Raman spectrometry, x-ray diffraction, and x-ray photoelectron spectroscopy. These measurements provide definitive evidence for high-crystalline quality diamond film, which is synthesized on a SiC rather than clean Si substrate. Characterization through atomic force microscope allows establishing fine quality criteria of the film according to the grain size of nanodiamond along with SiC. The diamond films exhibit a low-threshold (55 V/μm) and high current-density (1.6 mA/cm 2 ) field-emission (FE) display. The possible mechanism of formation of diamond films and their FE properties have been demonstrated.

Synthesis of Ceramic Protective Coatings for Chemical Plant Parts Operated in Hi-temperature and Corrosive/Erosive Environment

International Nuclear Information System (INIS)

Son, M. C.; Park, J. R.; Hong, K. T.; Seok, H. K.

2005-01-01

Some feasibility studies are conducted to produce an advanced ceramic coating, which reveals superior chemical and mechanical strength, on metal base structure used in chemical plant. This advanced coating on metallic frame can replace ceramic delivery pipe and reaction chamber used in chemical plant, which are operated in hi-temperature and corrosive/erosive environment. An dual spraying is adopted to reduce the residual stress in order to increase the coating thickness and the residual stress is estimated by in-situ manner. Then new methodology is tried to form special coating of yttrium aluminum garnet(YAG), which reveals hi-strength and low-creep rates at hi-temperature, superior anti-corrosion property, hi-stability against Alkali-Vapor corrosion, and so on, on iron base structure. To verify the formation of YAG during thermal spraying, XRD(X ray diffraction) technique was used

Properties of DLC coatings deposited by dc and dc with superimposed pulsed vacuum arc

International Nuclear Information System (INIS)

Zavaleyev, V.; Walkowicz, J.; Aksyonov, D.S.; Luchaninov, A.A.; Reshetnyak, E.N.; Strel'nitskij, V.E.

2014-01-01

Comparative studies of the structure, mechanical and tribological properties of DLC coatings deposited in DC and DC with superimposed high current pulse modes of operation vacuum-arc plasma source with the graphite cathode are presented. Imposition the pulses of high current on DC vacuum-arc discharge allows both increase the deposition rate of DLC coating and reduce the residual compressive stress in the coatings what promotes substantial improvement the adhesion to the substrate. Effect of vacuum arc plasma filtration with Venetian blind filter on the deposition rate and tribological characteristics of the coatings analyzed.

Research and development in the field of radiation curable coating systems

International Nuclear Information System (INIS)

Demmler, K.; Goethlich, L.; Osterloh, R.; Zosel, A.

1977-08-01

Suitable monomers for radiation curable coatings are mono- and polyfunctional acrylates and N vinylcompounds like vinylpyrrolidone and divinylpropyleneurea. Methacrylates, vinylesters and vinylethers are less suited. The residual monomer content of two completely cured coatings (UP and epoxyacrylate resins) amounts to 0.01 to 0.05%. Electron beam cured UP/acrylate films are particularly soil resistant. Peroxide and electron beam cured UP resin coatings differ in their curing pattern. Development of radiation sources now allows for testing radiation curable coatings on laboratory units. Modern EB and UV radiators deliver comparable results. The patent literature on electron beam curing comprises more than 700 known applications. In the course of the work described herein 4 patents were applied for. (orig.) [de

SiC fiber and yttria-stabilized zirconia composite thick thermal barrier coatings fabricated by plasma spray

Science.gov (United States)

Ma, Rongbin; Cheng, Xudong; Ye, Weiping

2015-12-01

Approximately 4 mm-thick SiC fiber/yttria-stabilized zirconia (YSZ) composite thermal barrier coatings (TBCs) were prepared by atmospheric plasma spray (APS). The composite coatings have a 'reinforced concrete frame structure', which can protect the coating from failure caused by increasing thickness of coating. The SiC fiber plays an important role in reducing the residual stress level of the composite coatings. The thermal conductivity (TC) value of the composite coatings is 0.632 W/m K, which is about 50% reduction compared to that of typical APS YSZ TBCs. And the composite coatings have higher fracture toughness and better thermal shock resistance than the YSZ TBCs.

Cutting Performance of Low Stress Thick TiAlN PVD Coatings during Machining of Compacted Graphite Cast Iron (CGI

Directory of Open Access Journals (Sweden)

Kenji Yamamoto

2018-01-01

Full Text Available A new family of physical vapor deposited (PVD coatings is presented in this paper. These coatings are deposited by a superfine cathode (SFC using the arc method. They combine a smooth surface, high hardness, and low residual stresses. This allows the production of PVD coatings as thick as 15 µm. In some applications, in particular for machining of such hard to cut material as compacted graphite iron (CGI, such coatings have shown better tool life compared to the conventional PVD coatings that have a lower thickness in the range of up to 5 μm. Finite element modeling of the temperature/stress profiles was done for the SFC coatings to present the temperature/stress profiles during cutting. Comprehensive characterization of the coatings was performed using XRD, TEM, SEM/EDS studies, nano-hardness, nano-impact measurements, and residual stress measurements. Application of the coating with this set of characteristics reduces the intensity of buildup edge formation during turning of CGI, leading to longer tool life. Optimization of the TiAlN-based coatings composition (Ti/Al ratio, architecture (mono vs. multilayer, and thickness were performed. Application of the optimized coating resulted in a 40–60% improvement in the cutting tool life under finishing turning of CGI.

Mechanical Properties of Plasma Sprayed Alumina Coatings

Czech Academy of Sciences Publication Activity Database

Kovářík, O.; Nohava, Jiří; Siegel, J.

2003-01-01

Roč. 48, č. 2 (2003), s. 129-145 ISSN 0001-7043 R&D Projects: GA ČR GA106/01/0094 Institutional research plan: CEZ:AV0Z2043910 Keywords : plasma sprayed alumina coatings, fatigue test, metalography, fractography, residual stress, microhardness, Young's modulus , four-point bending Subject RIV: BL - Plasma and Gas Discharge Physics

Multilayer composition coatings for cutting tools: formation and performance properties

Science.gov (United States)

Tabakov, Vladimir P.; Vereschaka, Anatoly S.; Vereschaka, Alexey A.

2018-03-01

The paper considers the concept of a multi-layer architecture of the coating in which each layer has a predetermined functionality. Latest generation of coatings with multi-layered architecture for cutting tools secure a dual nature of the coating, in which coatings should not only improve the mechanical and physical characteristics of the cutting tool material, but also reduce the thermo-mechanical effect on the cutting tool determining wear intensity. Here are presented the results of the development of combined methods of forming multi-layer coatings with improved properties. Combined method of forming coatings using a pulsed laser allowed reducing excessively high levels of compressive residual stress and increasing micro hardness of the multilayered coatings. The results in testing coated HSS tools showed that the use of additional pulse of laser processing increases tool life up to 3 times. Using filtered cathodic vacuum arc deposition for the generation of multilayer coatings based on TiAlN compound has increased the wear-resistance of carbide tools by 2 fold compared with tool life of cutting tool with commercial TiN coatings. The aim of this study was to develop an innovative methodological approach to the deposition of multilayer coatings for cutting tools with functional architectural selection, properties and parameters of the coating based on sound knowledge of coating failure in machining process.

Biomedical applications of diamond-like carbon coatings: a review.

Science.gov (United States)

Roy, Ritwik Kumar; Lee, Kwang-Ryeol

2007-10-01

Owing to its superior tribological and mechanical properties with corrosion resistance, biocompatibility, and hemocompatibility, diamond-like carbon (DLC) has emerged as a promising material for biomedical applications. DLC films with various atomic bond structures and compositions are finding places in orthopedic, cardiovascular, and dental applications. Cells grew on to DLC coating without any cytotoxity and inflammation. DLC coatings in orthopedic applications reduced wear, corrosion, and debris formation. DLC coating also reduced thrombogenicity by minimizing the platelet adhesion and activation. However, some contradictory results (Airoldi et al., Am J Cardiol 2004;93:474-477, Taeger et al., Mat-wiss u Werkstofftech 2003;34:1094-1100) were also reported that no significant improvement was observed in the performance of DLC-coated stainless stent or DLC-coated femoral head. This controversy should be discussed based on the detailed information of the coating such as atomic bond structure, composition, and/or electronic structure. In addition, instability of the DLC coating caused by its high level of residual stress and poor adhesion in aqueous environment should be carefully considered. Further in vitro and in vivo studies are thus required to confirm its use for medical devices.

Microstructural characterisation of electrodeposited coatings of metal matrix composite with alumina nanoparticles

International Nuclear Information System (INIS)

Indyka, P; Beltowska-Lehman, E; Bigos, A

2012-01-01

In the present work a nanocrystalline Ni-W metallic matrix was used to fabricate Ni-W/Al 2 O 3 composite coatings. The MMC (metal matrix composite) coatings with inert α-Al 2 O 3 particles (30 - 90 nm) were electrodeposited from aqueous electrolytes under direct current (DC) and controlled hydrodynamic conditions in a system with a rotating disk electrode (RDE). The chemical composition and microstructure of electrodeposited composites mainly control their functional properties; however, the particles must be uniformly dispersed to exhibit the dispersion-hardening effect. In order to increase the alumina particles incorporation as well as to promote the uniform distribution of the ceramic phase in a matrix, outer ultrasonic field was applied during electrodeposition. The influence of embedded alumina nanoparticles on structural characteristics (morphology, phase composition, residual stresses) of the resulting Ni-W/Al 2 O 3 coatings was investigated in order to obtain a nanocomposite with high hardness and relatively low residual stresses. Surface and cross-section morphology and the chemical composition of deposits was examined in the scanning electron microscope, the EDS technique was used. Microstructure and phase composition were determined by transmission electron microscopy and X-ray diffraction. Based on microstructural and micromechanical properties of the coatings, the optimum conditions for obtaining crack-free homogeneous Ni-W/Al 2 O 3 composite coatings have been determined.

Quantitative Evaluation of Contamination on Dental Zirconia Ceramic by Silicone Disclosing Agents after Different Cleaning Procedures

Directory of Open Access Journals (Sweden)

Sebastian Wille

2015-05-01

Full Text Available The aim of this study was to evaluate the effectiveness of cleaning procedures for air-abraded zirconia after contamination with two silicone disclosing agents. Air-abraded zirconia ceramic specimens (IPS e.max ZirCAD were contaminated with either GC Fit Checker white or GC Fit Checker II. Untreated zirconia specimens were used as control. Afterwards the surfaces were cleaned either with waterspray or ultrasonically in 99% isopropanol or using a newly developed cleaning paste (Ivoclean. After cleaning X-ray photoelectron spectroscopy (XPS was performed and the relative peak intensities of Zr, C and Si were used for a qualitative comparison of the residuals. There was no significant difference between the two different silicone disclosing agents. An additional cleaning step with isopropanol led to a significantly lower amount of residuals on the surface, but an additional cleaning process with Ivoclean did not reduce the amount of carbon residuals in comparison to the isopropanol cleaning. Just the silicone amount on the surface was reduced. None of the investigated cleaning processes removed all residuals from the contaminated surface. Standard cleaning processes do not remove all residuals of the silicone disclosing agent from the surface. This may lead to a failure of the resin-ceramic bonding.

Fracture and Residual Characterization of Tungsten Carbide Cobalt Coatings on High Strength Steel

National Research Council Canada - National Science Library

Parker, Donald S

2003-01-01

Tungsten carbide cobalt coatings applied via high velocity oxygen fuel thermal spray deposition are essentially anisotropic composite structures with aggregates of tungsten carbide particles bonded...

Modeling the Influence of Process Parameters and Additional Heat Sources on Residual Stresses in Laser Cladding

Science.gov (United States)

Brückner, F.; Lepski, D.; Beyer, E.

2007-09-01

In laser cladding thermal contraction of the initially liquid coating during cooling causes residual stresses and possibly cracks. Preweld or postweld heating using inductors can reduce the thermal strain difference between coating and substrate and thus reduce the resulting stress. The aim of this work is to better understand the influence of various thermometallurgical and mechanical phenomena on stress evolution and to optimize the induction-assisted laser cladding process to get crack-free coatings of hard materials at high feed rates. First, an analytical one-dimensional model is used to visualize the most important features of stress evolution for a Stellite coating on a steel substrate. For more accurate studies, laser cladding is simulated including the powder-beam interaction, the powder catchment by the melt pool, and the self-consistent calculation of temperature field and bead shape. A three-dimensional finite element model and the required equivalent heat sources are derived from the results and used for the transient thermomechanical analysis, taking into account phase transformations and the elastic-plastic material behavior with strain hardening. Results are presented for the influence of process parameters such as feed rate, heat input, and inductor size on the residual stresses at a single bead of Stellite coatings on steel.

Antireflection coatings for intraocular lenses of sapphire and fianite

Energy Technology Data Exchange (ETDEWEB)

Babin, A.A.; Konoplev, Yu.N.; Mamaev, Yu.A. [Inst. of Applied Physics, Nizhnii Novgorod (Russian Federation)] [and others

1995-10-01

Broadband antireflection coatings for intraocular lenses of sapphire and fianite are calculated and implemented practically. Their residual reflectance in the liquid with a refracting index of 1.336 is below 0.2% from each face virtually over the entire visible region. 7 refs., 2 figs., 2 tabs.

Correlating Coating Characteristics with the Performance of Drug-Coated Balloons – A Comparative In Vitro Investigation of Own Established Hydrogel- and Ionic Liquid-Based Coating Matrices

Science.gov (United States)

Kaule, Sebastian; Minrath, Ingo; Stein, Florian; Kragl, Udo; Schmidt, Wolfram; Schmitz, Klaus-Peter; Sternberg, Katrin; Petersen, Svea

2015-01-01

Drug-coated balloons (DCB), which have emerged as a therapeutic alternative to drug-eluting stents in percutaneous cardiovascular intervention, are well described with regard to clinical efficacy and safety within a number of clinical studies. In vitro studies elucidating the correlation between coating additive and DCB performance are however rare but considered important for the understanding of DCB requirements and the improvement of established DCB. In this regard, we examined three different DCB-systems, which were developed in former studies based on the ionic liquid cetylpyridinium salicylate, the body-own hydrogel hyaluronic acid and the pharmaceutically well-established hydrogel polyvinylpyrrolidone, considering coating morphology, coating thickness, drug-loss, drug-transfer to the vessel wall, residual drug-concentration on the balloon surface and entire drug-load during simulated use in an in vitro vessel model. Moreover, we investigated particle release of the different DCB during simulated use and determined the influence of the three coatings on the mechanical behavior of the balloon catheter. We could show that coating characteristics can be indeed correlated with the performance of DCB. For instance, paclitaxel incorporation in the matrix can reduce the drug wash-off and benefit a high drug transfer. Additionally, a thin coating with a smooth surface and high but delayed solubility can reduce drug wash-off and decrease particle burden. As a result, we suggest that it is very important to characterize DCB in terms of mentioned properties in vitro in addition to their clinical efficacy in order to better understand their function and provide more data for the clinicians to improve the tool of DCB in coronary angioplasty. PMID:25734818

Influence of Surface Properties and Impact Conditions on Adhesion of Insect Residues

Science.gov (United States)

Wohl, Christopher J.; Smith, Joseph G.; Connell, John W.; Siochi, Emilie J.; Doss, Jereme R.; Shanahan, Michelle H.; Penner, Ronald K.

2015-01-01

Insect residues can cause premature transition to turbulent flow on laminar flow airfoils. Engineered surfaces that mitigate the adhesion of insect residues provide, therefore, a route to more efficient aerodynamics and reduced fuel burn rates. Areal coverage and heights of residues depend not only on surface properties, but also on impact conditions. We report high speed photography of fruit fly impacts at different angles of inclination on a rigid aluminum surface, optical microscopy and profilometry, and contact angle goniometry to support the design of engineered surfaces. For the polyurethane and epoxy coatings studied, some of which exhibited superhydrophobicity, it was determined that impact angle and surface compositions play critical roles in the efficacy of these surfaces to reduce insect residue adhesion.

Effect of Surface Roughness and Structure Features on Tribological Properties of Electrodeposited Nanocrystalline Ni and Ni/Al2O3 Coatings

Science.gov (United States)

Góral, Anna; Lityńska-Dobrzyńska, Lidia; Kot, Marcin

2017-05-01

Metal matrix composite coatings obtained by electrodeposition are one of the ways of improving the surfaces of materials to enhance their durability and properties required in different applications. This paper presents an analysis of the surface topography, microstructure and properties (residual stresses, microhardness, wear resistance) of Ni/Al2O3 nanocomposite coatings electrodeposited on steel substrates from modified Watt's-type baths containing various concentrations of Al2O3 nanoparticles and a saccharin additive. The residual stresses measured in the Ni/Al2O3 coatings decreased with an increasing amount of the co-deposited ceramics. It was established that the addition of Al2O3 powder significantly improved the coatings' microhardness. The wear mechanism changed from adhesive-abrasive to abrasive with a rising amount of Al2O3 particles and coating microhardness. Nanocomposite coatings also exhibited a lower coefficient of friction than that of a pure Ni-electrodeposited coating. The friction was found to depend on the surface roughness, and the smoother surfaces gave lower friction coefficients.

Erosion resistance and adhesion of composite metal/ceramic coatings produced by plasma spraying

International Nuclear Information System (INIS)

Ramm, D.A.J.; Hutchings, I.M.; Clyne, T.W.

1993-01-01

Ceramic coatings can exhibit greater erosion resistance than most metallic coatings. Such coatings are conveniently produced by thermal spraying. Unfortunately, thermally sprayed ceramic coatings often exhibit poor adhesion, partly as a consequence of the development of residual stresses during spraying and subsequent cooling. Composite coatings have been studied using aluminium/alumina deposits on steel substrates. The incorporation of ceramics within a ductile matrix has potential for sharply reducing the erosive wear at high erodent impact angles, whilst retaining the good erosion resistance of ceramics at low angles. It is shown that the proportion of metal and ceramic at the free surface can be specified so as to optimise the erosion resistance. Experiments have also been carried out on the resistance of the coatings to debonding during four-point bending of the coated substrate. Progress is being made towards the tailoring of composition profiles in graded coatings so as to optimise the combination of erosion resistance and adhesion. (orig.)

Laser shock peening without coating induced residual stress distribution, wettability characteristics and enhanced pitting corrosion resistance of austenitic stainless steel

Science.gov (United States)

Prabhakaran, S.; Kulkarni, Aniket; Vasanth, G.; Kalainathan, S.; Shukla, Pratik; Vasudevan, Vijay K.

2018-01-01

Low energy laser shock peening without coating (LSPwC) was conducted on AISI 304 austenitic stainless steel specimens with varying pulse densities or overlapping. Highest magnitude of compressive residual stress (CRS) was achieved for an optimized pulse density of 2500 pulses/cm2 (75% overlapping). The 2-D and 3-D topographical analysis were indicative of the fact that controlled roughening of the surface was achieved after the LSPwC process. After the LSPwC process, the hydrophilic unpeened surface was converted into the hydrophobic surface, thus decreasing the wettability characteristics of the surface. The X-ray diffraction (XRD) results reveal that there is a beginning of the martensite transformation and the rise in the intensity value of the peaks after LSPwC indicates the presence of compressive residual stresses induced in the specimen. The optical microscope and high-resolution transmission electron microscope results provided evidence of grain refinement and deformation induced refinement features such as multidirectional mechanical twinning, dislocations lines, micro shear cells and stacking faults in the near and sub-surface areas. The average hardness value of the LSPwC specimens was found to be increased by 28% more than the untreated specimen. The potentiodynamic polarization revealed that there was a considerable amount of increase in the pitting corrosion resistance after the LSPwC process, thus, supporting to extend the fatigue life of the specimen. The electrochemical impedance spectroscopic (EIS) analysis depicts that the LSPwC process supports the formation of the strong passivation layer in 3.5% NaCl solution.

Paint coating characterization for thermoelastic stress analysis of metallic materials

International Nuclear Information System (INIS)

Robinson, A F; Dulieu-Barton, J M; Quinn, S; Burguete, R L

2010-01-01

In thermoelastic stress analysis (TSA) it is normal practice to coat metallic specimens with black paint to enhance and standardize the surface emissivity. It is assumed that the paint coating has no effect on the thermal emission from the specimen, but it is well known that the response is sensitive to paint coating thickness, particularly at higher frequencies. In this paper the effects of loading frequency and paint coating thickness on the thermoelastic response are investigated. The thermoelastic response is compared to theory, and optimum test conditions and coating characteristics are suggested. The motivation for the work is to develop a TSA-based means of residual stress assessment, where the measurement of much smaller temperature changes than those that are resolved in standard TSA is required; therefore the analysis is much more sensitive to the effects of the paint coating. However, the work presented in this paper is relevant to a wide range of TSA investigations and presents data that will be of interest to all practitioners of TSA

Anti-sticking behavior of DLC-coated silicon micro-molds

International Nuclear Information System (INIS)

Saha, B; Tor, S B; Liu, E; Khun, N W; Hardt, D E; Chun, J H

2009-01-01

Pure carbon- (C), nitrogen- (N) and titanium- (Ti) doped diamond-like carbon (DLC) coatings were deposited on silicon (Si) micro-molds by dc magnetron sputtering deposition to improve the tribological performance of the micro-molds. The coated and uncoated Si molds were used in injection molding for the fabrication of secondary metal-molds, which were used for the replication of micro-fluidic devices. The bonding structure, surface roughness, surface energy, critical load and friction coefficient of the DLC coatings were characterized with micro-Raman spectroscopy, atomic force microscopy (AFM), contact angle, microscratch and ball-on-disc sliding wear tests, respectively. It was observed that the doping conditions had significant effects on Raman peak positions, mechanical and tribological properties of the coatings. The G peak shifted toward a lower position with N and Ti doping. The DLC coating deposited with 1 sccm N 2 flow rate showed the lowest G peak position and the smoothest surface. The surface energies of the pure carbon and Ti-doped DLC coatings were lower than that of the N-doped DLC, which was more significant at a higher N 2 flow rate. In terms of adhesion and friction coefficient, it was observed that the Ti-doped DLC coating had the best performance. Ti incorporated in the DLC coating decreased the residual stress of the coating, which improved the adhesive strength of the coating with the Si substrate

Laser coating of aluminum alloy EN AW 6082-T651 with TiB2 and TiC: Microstructure and mechanical properties

Science.gov (United States)

Ravnikar, Dunja; Dahotre, Narendra B.; Grum, Janez

2013-10-01

This paper deals with laser coating of ceramics by deposition of a precursor powder mixture of TiB2-TiC-Al on an EN AW 6082-T651 aluminum alloy. The resulting coating was studied by means of a microstructural and mechanical analysis. The coating has with TiC and TiB2 particles of various shapes and sizes embedded in an Al matrix, as well as being adherent and free of cracks with an average porosity lower than 2%. Microhardness in the coating is 40% higher than the uncoated alloy, while the microhardness in the laser melt zone and heat-affected zone dropped significantly. The wear test showed a great improvement in terms of the mass lost after the 30 min test. The three-point bending test was used to determine the flexural properties of the coated aluminum alloy. Higher content of TiB2 in ceramic components increases the flexural strength of the coated specimens, delaying the occurrence of the first crack in the coating or the occurrence of delamination. The measurements of residual stresses confirmed the presence of favorable compressive residual stresses in the surface coating. With depth, these stresses become tensile.

Assessment of a residual life evaluation tool for gas turbine blades and vanes based on microstructural evolution of a NiCoCrAlY+Re coating

Energy Technology Data Exchange (ETDEWEB)

Barbareschi, E.; Bonadei, A.; Costa, A.; Guarnone, P.; Vacchieri, E. [Ansaldo Energia S.p.A., Genoa (Italy)

2010-07-01

Life management of hot gas path components is a fundamental topic in gas turbine for power generation. The gas turbine components have to withstand severe service conditions in term of high temperature oxidation, corrosion and creep-fatigue. The resistance to environmental conditions is assured by metallic coatings of the MCrAlY family. {beta} phase, NiAl, present as secondary phase, is the source of protection against oxidation. Among MCrAlY coatings, NiCoCrAlY + Re have a complex microstructure with a higher number of phases than the standard ones; these phases are subjected to transformations during service. The addition of Re is effective against the diffusion of protective elements, as Al and Cr, toward the base material. For the estimation of residual life a first approach has been developed using the decrease of {beta} phase amount after static oxidation test at high temperature and for long time. This type of prediction tool is not complete for the assessment of the hot gas path components life management and a deep study focused on the transformation of the other phases is necessary. Experimental tests have been performed to identify the phase stability range by annealing at different temperatures and durations. Moreover after static oxidation tests a systematic data collection of phase evolution has been carried out through EDS, XRD and EBSD techniques in order to define the kinetic laws that rule the phase transformations. The tuning of thermodynamic and kinetic results allows to build up another residual life tool that, even if it is more complex, is more reliable in temperature evaluation in GT components. Both models have been applied to a component after service and a comparison between the different models evaluation has been conducted. (orig.)

X-ray diffraction characterization of electrodeposited Ni–Al composite coatings prepared at different current densities

International Nuclear Information System (INIS)

Cai, Fei; Jiang, Chuanhai; Wu, Xueyan

2014-01-01

Highlights: • Different X-ray diffraction techniques were applied to characterize the Ni–Al composite coatings. • Al 2 O 3 formed on the coating surface after potentiostatic polarization experiments. • The relationship between corrosion and the Al content and the texture were also investigated. - Abstract: Ni–Al composite coatings were prepared at different applied current densities (1–8 A/dm 2 ) from a conventional Watt bath. The influences of current densities on the texture, grain size, microstrain, residual stress of the Ni–Al composite coating were investigated with X-ray diffraction method, which includes texture coefficients (TC) and pole figures, Voigt method, classical sin 2 ψ X-ray diffraction method and the Multi-reflection grazing incidence geometry (referred to as MGIXD) method. The morphology, composition, anti-corrosion properties and friction coefficients at 200 °C of the coating were also studied. The results showed that the texture of coating deposited at higher current densities evolved from the (2 0 0) preferred orientation with fiber texture to random orientation with reducing current density. Al particle content increased with reducing current density, grain size decreased with the reducing current density, while the microstrain and the tensile residual stresses increased. The MGIXD result showed stress gradient on the near-surface of the coating. Potentiodynamic polarization results demonstrated that the Ni–Al coating deposited at 2 A/dm 2 exhibited the best anti-corrosion which was contributed by the formation of Al 2 O 3 on the surface. The minimum friction coefficient of 0.57 was also observed for coating deposited at 4 A/dm 2

Neuro - Fuzzy Analysis for Silicon Carbide Abrasive Grains ...

African Journals Online (AJOL)

Grinding wheels are made of very small, sharp and hard abrasive materials or grits held together by strong porous bond. Abrasive materials are materials of extreme hardness that are used to shape other materials by a grinding or abrading action and they are used either as loose grains, as grinding wheels, or as coatings ...

Characterization of abrasion-induced nanoparticle release from paints into liquids and air

Science.gov (United States)

Golanski, L.; Gaborieau, A.; Guiot, A.; Uzu, G.; Chatenet, J.; Tardif, F.

2011-07-01

Two standard methods for the characterization of the abrasion nanoparticle release into air and liquid from coatings containing nanoparticles were developed. Details of the abrasion processes and the measurement methods are shown. Paints were formulated in an industrial facility. Standard abrasion conditions in wet environments were simulated. The size distribution of the particles abraded into liquid was analyzed by a laser granulometer: submicrometric and micrometric particles were observed, but no nanometric particles. The nanoparticles released in liquid were deposited on filters for SEM (Scanning Electron Microscopy) analysis. No free or agglomerated nanoparticles were observed by SEM: nanoparticles seem to remain embedded in the paint matrix. The same coatings were abraded in the air using another standard method. The ELPI (Electrical Low Pressure Impactor) was used to determine the number size distribution of the dust generated. Abrasion is found to produce submicrometric and micrometric particles in the air but no nanoparticles. Further characterizations by SEM confirmed that no free or agglomerated nanoparticles were emitted: nanoparticles seem to remain embedded in the paint matrix.

Characterization of abrasion-induced nanoparticle release from paints into liquids and air

International Nuclear Information System (INIS)

Golanski, L; Guiot, A; Uzu, G; Tardif, F; Gaborieau, A; Chatenet, J

2011-01-01

Two standard methods for the characterization of the abrasion nanoparticle release into air and liquid from coatings containing nanoparticles were developed. Details of the abrasion processes and the measurement methods are shown. Paints were formulated in an industrial facility. Standard abrasion conditions in wet environments were simulated. The size distribution of the particles abraded into liquid was analyzed by a laser granulometer: submicrometric and micrometric particles were observed, but no nanometric particles. The nanoparticles released in liquid were deposited on filters for SEM (Scanning Electron Microscopy) analysis. No free or agglomerated nanoparticles were observed by SEM: nanoparticles seem to remain embedded in the paint matrix. The same coatings were abraded in the air using another standard method. The ELPI (Electrical Low Pressure Impactor) was used to determine the number size distribution of the dust generated. Abrasion is found to produce submicrometric and micrometric particles in the air but no nanoparticles. Further characterizations by SEM confirmed that no free or agglomerated nanoparticles were emitted: nanoparticles seem to remain embedded in the paint matrix.

Residual stress analysis for engineering applications by means of neutron diffraction

International Nuclear Information System (INIS)

Gnaeupel-Herold, T.; Brand, P.C.; Prask, H.J.

1999-01-01

Residual stresses originate from spatial differences in plastic deformation, temperature, or phase distribution, introduced by manufacturing processes or during service. Engineering parts and materials experience mechanical, thermal, and chemical loads during their service, and most of these loads introduce stresses that are superimposed on the already existing residual stresses. Residual stresses can therefore limit or improve life and strength of engineering parts; knowledge and understanding of these stresses is therefore critical for optimizing strength and durability. The economic and scientific importance of neutron diffraction residual stress analysis has led to an increasing number of suitable instruments worldwide. All of the major sources due in the next several years will have instruments for the sole purpose of performing residual stress and texture measurements. Recently, a dedicated, state-of-the-art diffractometer has been installed at the National Institute of Standards and Technology reactor. It has been used for a variety of measurements on basic and engineering stress problems. Among the most prominent examples that have been investigated in collaboration with industrial and academic partners are residual stresses in rails, weldments, and plasma-sprayed coatings

Mo doped DLC nanocomposite coatings with improved mechanical and blood compatibility properties

Energy Technology Data Exchange (ETDEWEB)

Tang, X.S. [School of Physics Science and Technology, Zhanjiang Normal University, Zhanjiang 524048 (China); Development Center for New Materials Engineering and Technology in Universities of Guangdong, Zhanjiang 524048 (China); Wang, H.J.; Feng, L. [School of Physics Science and Technology, Zhanjiang Normal University, Zhanjiang 524048 (China); Shao, L.X. [School of Physics Science and Technology, Zhanjiang Normal University, Zhanjiang 524048 (China); Development Center for New Materials Engineering and Technology in Universities of Guangdong, Zhanjiang 524048 (China); Zou, C.W., E-mail: qingyihaiyanas@163.com [School of Physics Science and Technology, Zhanjiang Normal University, Zhanjiang 524048 (China); Development Center for New Materials Engineering and Technology in Universities of Guangdong, Zhanjiang 524048 (China)

2014-08-30

Highlights: • Mo doped diamond like carbon coatings were deposited by magnetron sputtering. • The blood compatibility of Mo-DLC coatings was observed through platelet adhesion. • The amount of thrombus on the Mo-DLC is much less than that of pyrolytic carbon. - Abstract: Mo (molybdenum) doped diamond like carbon (Mo-DLC) coatings with improved mechanical and blood compatibility properties were deposited by closed field unbalanced magnetron sputtering. The undoped and Mo-doped DLC coatings were analyzed by various characterization techniques such as Raman spectra, Atomic force microscopy, and temperature-dependent frictional wear testing. The results showed that the Mo-DLC coating with low Mo concentration was a effective protective coating with reduced residual stress and increased cohesive strength, and kept good wear resistance at the ambient temperature of 500 °C. The blood compatibility of Mo-DLC coatings was investigated by platelet adhesion. The results showed that the amount of thrombus on the Mo-DLC nanocomposite coatings was much less than that of thrombus on pyrolytic carbon films. The Mo-DLC nanocomposite coatings would be a new kind of promising materials applied to artificial heart valve and endovascula stent.

Mo doped DLC nanocomposite coatings with improved mechanical and blood compatibility properties

International Nuclear Information System (INIS)

Tang, X.S.; Wang, H.J.; Feng, L.; Shao, L.X.; Zou, C.W.

2014-01-01

Highlights: • Mo doped diamond like carbon coatings were deposited by magnetron sputtering. • The blood compatibility of Mo-DLC coatings was observed through platelet adhesion. • The amount of thrombus on the Mo-DLC is much less than that of pyrolytic carbon. - Abstract: Mo (molybdenum) doped diamond like carbon (Mo-DLC) coatings with improved mechanical and blood compatibility properties were deposited by closed field unbalanced magnetron sputtering. The undoped and Mo-doped DLC coatings were analyzed by various characterization techniques such as Raman spectra, Atomic force microscopy, and temperature-dependent frictional wear testing. The results showed that the Mo-DLC coating with low Mo concentration was a effective protective coating with reduced residual stress and increased cohesive strength, and kept good wear resistance at the ambient temperature of 500 °C. The blood compatibility of Mo-DLC coatings was investigated by platelet adhesion. The results showed that the amount of thrombus on the Mo-DLC nanocomposite coatings was much less than that of thrombus on pyrolytic carbon films. The Mo-DLC nanocomposite coatings would be a new kind of promising materials applied to artificial heart valve and endovascula stent

“Combined Occlusion and Atropine Therapy” Versus “Augmented Part-Time Patching” in Children with Refractory/Residual Amblyopia: A Pilot Study

Science.gov (United States)

Sachdeva, Virender; Mittal, Vaibhev; Gupta, Varun; Gunturu, Rekha; Kekunnaya, Ramesh; Chandrasekharan, Anjali; Chabblani, Preeti Patil; Rao, Harsha L.

2016-01-01

Purpose: To compare the efficacy of combined occlusion and atropine therapy (COAT) and augmented part-time patching for the treatment of unilateral refractory/residual amblyopia. Methodology: This retrospective study evaluated children between 4 and 11 years with refractory/residual amblyopia who were treated with either additional atropine (COAT group) or increased hours of patching (augmented group). Data were collected on improvement in best-corrected visual acuity (BCVA; logarithm of the minimum angle of resolution [logMAR] units) at each follow-up visit. Results: There were 19 children in the COAT group and 17 children in the augmented group. The baseline BCVA of the amblyopic eye was 0.79 ± 0.36 logMAR in the COAT group and 0.72 ± 0.26 logMAR in augmented group. Children were statistically significantly younger in the COAT group (6.4 ± 2.2 years) compared to the augmented group (8.6 ± 3.3 years, P = 0.02). The mean duration of follow-up was statistically significantly longer in the augmented group (20.2 COAT group; 13.9 months augmented group) (P = 0.03). Compliance was similar in both groups. LogMAR BCVA (adjusted for difference in age and baseline BCVA) was statistically significantly better in the COAT group (0.56 ± 0.04) compared to the augmented group (0.80 ± 0.04) at 3 months (P = 0.000); 6 months (COAT group, 0.50 ± 0.04 vs. augmented group, 0.74 ± 0.04; P = 0.04) and at 1 year (COAT group, 0.42 ± 0.04 vs. augmented group, 0.67 ± 0.04, P = 0.000). There was statistically significantly greater improvement in logMAR BCVA at 6 months in COAT group (0.26 ± 0.15) compared to the augmented group (0.02 ± 0.14), (P = 0.0002). Age, gender, pretreatment BCVA, duration of follow-up, or compliance to patching did not affect improvement in BCVA. Conclusions: COAT may result in greater improvement in BCVA than augmented part-time patching in children with unilateral residual/refractory amblyopia. PMID:27162453

Structurally Integrated, Damage-Tolerant, Thermal Spray Coatings

Science.gov (United States)

Vackel, Andrew; Dwivedi, Gopal; Sampath, Sanjay

2015-07-01

Thermal spray coatings are used extensively for the protection and life extension of engineering components exposed to harsh wear and/or corrosion during service in aerospace, energy, and heavy machinery sectors. Cermet coatings applied via high-velocity thermal spray are used in aggressive wear situations almost always coupled with corrosive environments. In several instances (e.g., landing gear), coatings are considered as part of the structure requiring system-level considerations. Despite their widespread use, the technology has lacked generalized scientific principles for robust coating design, manufacturing, and performance analysis. Advances in process and in situ diagnostics have provided significant insights into the process-structure-property-performance correlations providing a framework-enhanced design. In this overview, critical aspects of materials, process, parametrics, and performance are discussed through exemplary studies on relevant compositions. The underlying connective theme is understanding and controlling residual stresses generation, which not only addresses process dynamics but also provides linkage for process-property relationship for both the system (e.g., fatigue) and the surface (wear and corrosion). The anisotropic microstructure also invokes the need for damage-tolerant material design to meet future goals.

Effects of laser remelting on microstructures and immersion corrosion performance of arc sprayed Al coating in 3.5% NaCl solution

Science.gov (United States)

Sun, Ze; Zhang, Donghui; Yan, Baoxu; Kong, Dejun

2018-02-01

An arc sprayed aluminum (Al) coating on S355 steel was processed using a laser remelting (LR). The microstructures, chemical element composition, and phases of the obtained Al coating were analyzed using a field mission scanning electronic microscope (FESEM), energy dispersive spectrometer (EDS), and X-ray diffractometer (XRD), respectively, and the residual stresses were measured using an X-ray diffraction stress tester. The immersion corrosion tests and potentiodynamic polarization of Al coating in 3.5% NaCl solution were performed to investigate the effects of LR on its immersion corrosion behaviors, and the corrosion mechanism of Al coating was also discussed. The results show that the arc sprayed Al coating is composed of Al phase, while that by LR is composed of Al-Fe and AlO4FeO6 phases, and the porosities and cracks in the arc sprayed Al coating are eliminated by LR, The residual stress of arc sprayed Al coating is -5.6 ± 18 MPa, while that after LR is 137.9 ± 12 MPa, which deduces the immersion corrosion resistance of Al coating. The corrosion mechanism of arc sprayed Al coating is pitting corrosion and crevice corrosion, while that by LR is uniform corrosion and pitting corrosion. The corrosion potential of arc sprayed Al coating by LR shifts positively, which improves its immersion corrosion resistance.

Microstructures and Properties of Laser Cladding Al-TiC-CeO₂ Composite Coatings.

Science.gov (United States)

He, Xing; Kong, Dejun; Song, Renguo

2018-01-26

Al-TiC-CeO₂ composite coatings have been prepared by using a laser cladding technique, and the microstructure and properties of the resulting composite coatings have been investigated using scanning electron microscopy (SEM), a 3D microscope system, X-ray diffraction (XRD), micro-hardness testing, X-ray stress measurements, friction and wear testing, and an electrochemical workstation. The results showed that an Al-Fe phase appears in the coatings under different applied laser powers and shows good metallurgical bonding with the matrix. The dilution rate of the coating first decreases and then increases with increasing laser power. The coating was transformed from massive and short rod-like structures into a fine granular structure, and the effect of fine grain strengthening is significant. The microhardness of the coatings first decreases and then increases with increasing laser power, and the maximum microhardness can reach 964.3 HV 0.2 . In addition, the residual stress of the coating surface was tensile stress, and crack size increases with increasing stress. When the laser power was 1.6 kW, the coating showed high corrosion resistance.

Failure characteristics and mechanisms of EB-PVD TBCs with Pt-modified NiAl bond coats

Energy Technology Data Exchange (ETDEWEB)

Zhou, Le; Mukherjee, Sriparna; Huang, Ke; Park, Young Whan; Sohn, Yongho, E-mail: Yongho.Sohn@ucf.edu

2015-06-18

Microstructural evolution and failure characteristics/mechanisms were investigated for thermal barrier coatings that consist of electron beam physical vapor deposited ZrO{sub 2}−8 wt% Y{sub 2}O{sub 3} (YSZ) topcoat, Pt-modified nickel aluminide, (Ni,Pt)Al bond coat, and CMSX-4 superalloy substrate with furnace cycling at 1100 °C with 1-h dwell. Photo stimulated luminescence spectroscopy, scanning electron microscopy equipped with X-ray energy dispersive spectroscopy and transmission electron microscopy were employed to examine the residual stress of the thermally grown oxide (TGO) and microstructural changes. For comparison, (Ni,Pt)Al bond coat on CMSX-4 without the YSZ topcoat was also characterized. The TGO grew faster for the YSZ-coated (Ni,Pt)Al bond coat than the (Ni,Pt)Al coating without the YSZ topcoat. Correspondingly, the β-to-γ′/martensite formation in the (Ni,Pt)Al bond coat occurred faster on the YSZ-coated (Ni,Pt)Al bond coat. However the rumpling occurred much faster and with larger amplitude on the (Ni,Pt)Al coating without the YSZ topcoat. Still, the rumpling at the TGO/bond coat interface caused crack initiation as early as 10 thermal cycles, decohesion at the YSZ/TGO interface, and eventual spallation failure primarily through the TGO/bond coat interface. The magnitude of compressive residual stress in the TGO showed an initial increase up to 3−4 GPa followed by a gradual decrease. The rate of stress relaxation was much quicker for the TGO scale without the YSZ topcoat with distinctive relief corresponding to the cracking at the top of geometrical ridges associated with the (Ni,Pt)Al bond coat. The maximum elastic energy for the TGO scale was estimated at 90 J/m{sup 2} at 50% of its lifetime (N{sub f}=545 cycles). The YSZ presence/adhesion to the TGO scale is emphasized to minimize the undulation of the TGO/bond coat interface, i.e., decohesion at the YSZ/TGO scale accelerates the rumpling and crack-coalescence at the TGO/bond coat

40 CFR 761.375 - Specific requirements for surfaces coated or covered with dust, dirt, grime, grease, or another...

Science.gov (United States)

2010-07-01

... coated or covered with dust, dirt, grime, grease, or another absorbent material. 761.375 Section 761.375... coated or covered with dust, dirt, grime, grease, or another absorbent material. (a) First wash. Cover..., absorbent pad until the surface appears dry. This cleaning should remove any residual dirt, dust, grime, or...

The Potential of Sumatran Pine Rosin for Reinforcement-Steel Coating in Wet Environment

Directory of Open Access Journals (Sweden)

Rudi Hartono

2018-01-01

Full Text Available The corrosion of reinforcement-steel is commonly prevented by applying hydrophobic coating. In this work, the potential of residual product from Sumatran Pine sap distillation, known as Sumatran pine rosin or gondorukem, as a natural and environmentally-friendy resource to coat reinforcement-steel, and an initial assessment on its capability to prevent the corrosion in wet environment were investigated. The experiments were performed using two types of commercially available gondorukem, namely type T and U. The coated reinforcement-steel samples were immersed in collected rainwater and their physical changes were observed periodically for 60 days. The results showed that gondorukem improve the durability of the reinforcement-steel from corrosion in a severe rainwater contact. Keywords:  corrosion, coating, gondorukem, hydrophobic, pine rosin, reinforcement bar

A hierarchical structure through imprinting of a polyimide precursor without residual layers

International Nuclear Information System (INIS)

Pai, I-Ting; Hon, Min-Hsiung; Leu, Ing-Chi

2008-01-01

A patterned polyimide without a residual layer is obtained by imprinting with the assistance of a residual solvent. The effects of the wetting behaviors of the poly-amic acid (PAA) solution coated on various surfaces are examined and the formation of hierarchical patterns without residual layers is demonstrated. polydimethylsiloxane (PDMS) and PEI/PDMS are used as imprinting molds with Si and 300 nm SiO 2 /Si as substrates. The results indicate that the various ambits of patterns without a residual layer are formed due to the dewetting phenomena caused by surface tension (Suh 2006 Small 2 832). During imprinting, PDMS with a low surface energy makes the PAA solution flow away from its surface exposing the contact area due to dewetting. Self-organized hierarchical structures are also obtained from this process due to effective dewetting. The present study provides a new approach for fabricating patterns without residual layers and the consequent preparation of hierarchical structures, which is considered to be impossible using the lithographic technique

Finite element modelling of stress development during deposition of ion assisted coatings

International Nuclear Information System (INIS)

Ward, D.J.; Arnell, R.D.

2002-01-01

Ion assisted physical vapour deposited (IAPVD) films typically have a high state of residual stress. This residual stress comprises two components: a thermal stress, which forms as the system cools to room temperature; and an intrinsic stress which is caused by the processes of deposition. Much work has been published on the tribology and mechanical behaviour of surface coatings without consideration of the residual stress. It was therefore considered desirable to develop a finite element (FE) simulation to be used either as a precursor to any realistic mechanical study of the behaviour of such surface coatings, or to be used as a tool to study the effects of varying the deposition parameters. Previous experimental work has shown that the residual stress is related to deposition parameters, such as incident ion and atom fluxes and energies, and recent molecular dynamics studies have indicated that trapped inert gas species may play a major role in the mechanism for creation of the intrinsic stress. The FE simulation assumes that the processes of ion bombardment and material deposition are consecutive, but as the analysis time step tends to zero this assumption approximates the simultaneity of the processes. Suitable mathematical descriptions are employed in the bombarded region of the growing coating to simulate the macroscopic effects of the microscopic atomic collision phenomena and diffusion processes. Two finite element simulations are presented. The first is based on an analytical model, which has gained popular acceptance and this was presented in a previous year at this conference. The second builds on this to simulate wider aspects of known behaviour and is presented in this follow-up paper. The predicted trends of mean stress and its distribution are similar to those observed in published experimental work

Roles for the coat protein telokin-like domain and the scaffolding protein amino-terminus

Science.gov (United States)

Suhanovsky, Margaret M.; Teschke, Carolyn M.

2011-01-01

Assembly of icosahedral capsids of proper size and symmetry is not understood. Residue F170 in bacteriophage P22 coat protein is critical for conformational switching during assembly. Substitutions at this site cause assembly of tubes of hexamerically arranged coat protein. Intragenic suppressors of the ts phenotype of F170A and F170K coat protein mutants were isolated. Suppressors were repeatedly found in the coat protein telokin-like domain at position 285, which caused coat protein to assemble into petite procapsids and capsids. Petite capsid assembly strongly correlated to the side chain volume of the substituted amino acid. We hypothesize that larger side chains at position 285 torque the telokin-like domain, changing flexibility of the subunit and intercapsomer contacts. Thus, a single amino acid substitution in coat protein is sufficient to change capsid size. In addition, the products of assembly of the variant coat proteins were affected by the size of the internal scaffolding protein. PMID:21784500

Fire performance, microstructure and thermal degradation of an epoxy based nano intumescent fire retardant coating for structural applications

Energy Technology Data Exchange (ETDEWEB)

Aziz, Hammad, E-mail: engr.hammad.aziz03@gmail.com; Ahmad, Faiz, E-mail: faizahmad@petronas.com.my; Yusoff, P. S. M. Megat; Zia-ul-Mustafa, M. [Department of Mechanical Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, Tronoh 31750, Perak (Malaysia)

2015-07-22

Intumescent fire retardant coating (IFRC) is a passive fire protection system which swells upon heating to form expanded multi-cellular char layer that protects the substrate from fire. In this research work, IFRC’s were developed using different flame retardants such as ammonium polyphosphate, expandable graphite, melamine and boric acid. These flame retardants were bound together with the help of epoxy binder and cured together using curing agent. IFRC was then reinforced with nano magnesium oxide and nano alumina as inorganic fillers to study their effect towards fire performance, microstructure and thermal degradation. Small scale fire test was conducted to investigate the thermal insulation of coating whereas fire performance was calculated using thermal margin value. Field emission scanning electron microscopy was used to examine the microstructure of char obtained after fire test. Thermogravimetric analysis was conducted to investigate the residual weight of coating. Results showed that the performance of the coating was enhanced by reinforcement with nano size fillers as compared to non-filler based coating. Comparing both nano size magnesium oxide and nano size alumina; nano size alumina gave better fire performance with improved microstructure of char and high residual weight.

Thermal Shock Resistance of Stabilized Zirconia/Metal Coat on Polymer Matrix Composites by Thermal Spraying Process

Science.gov (United States)

Zhu, Ling; Huang, Wenzhi; Cheng, Haifeng; Cao, Xueqiang

2014-12-01

Stabilized zirconia/metal coating systems were deposited on the polymer matrix composites by a combined thermal spray process. Effects of the thicknesses of metal layers and ceramic layer on thermal shock resistance of the coating systems were investigated. According to the results of thermal shock lifetime, the coating system consisting of 20 μm Zn and 125 μm 8YSZ exhibited the best thermal shock resistance. Based on microstructure evolution, failure modes and failure mechanism of the coating systems were proposed. The main failure modes were the formation of vertical cracks and delamination in the outlayer of substrate, and the appearance of coating spallation. The residual stress, thermal stress and oxidation of substrate near the substrate/metal layer interface were responsible for coating failure, while the oxidation of substrate near the substrate/coating interface was the dominant one.

A Study of Deposition Coatings Formed by Electroformed Metallic Materials.

Directory of Open Access Journals (Sweden)

Shoji Hayashi

Full Text Available Major joining methods of dental casting metal include brazing and laser welding. However, brazing cannot be applied for electroformed metals since heat treatment could affect the fit, and, therefore, laser welding is used for such metals. New methods of joining metals that do not impair the characteristics of electroformed metals should be developed. When new coating is performed on the surface of the base metal, surface treatment is usually performed before re-coating. The effect of surface treatment is clinically evaluated by peeling and flex tests. However, these testing methods are not ideal for deposition coating strength measurement of electroformed metals. There have been no studies on the deposition coating strength and methods to test electroformed metals. We developed a new deposition coating strength test for electroformed metals. The influence of the negative electrolytic method, which is one of the electrochemical surface treatments, on the strength of the deposition coating of electroformed metals was investigated, and the following conclusions were drawn: 1. This process makes it possible to remove residual deposits on the electrodeposited metal surface layer. 2. Cathode electrolysis is a simple and safe method that is capable of improving the surface treatment by adjustments to the current supply method and current intensity. 3. Electrochemical treatment can improve the deposition coating strength compared to the physical or chemical treatment methods. 4. Electro-deposition coating is an innovative technique for the deposition coating of electroformed metal.

Residual stresses in as-sprayed and heat treated TBCs : measurements and FEM calculations

NARCIS (Netherlands)

Koolloos, M.F.J.; Houben, J.M.

2000-01-01

The first part of this paper concerns measurement of through-thickness residual stresses in TBCs by the hole-drilling method. The influences of top coat thickness and different thermal histories (furnace and burner rig) were determined. Low tensile stresses prevailed in the as-sprayed state, and low

Understanding cracking failures of coatings: A fracture mechanics approach

Science.gov (United States)

Kim, Sung-Ryong

A fracture mechanics analysis of coating (paint) cracking was developed. A strain energy release rate (G(sub c)) expression due to the formation of a new crack in a coating was derived for bending and tension loadings in terms of the moduli, thicknesses, Poisson's ratios, load, residual strain, etc. Four-point bending and instrumented impact tests were used to determine the in-situ fracture toughness of coatings as functions of increasing baking (drying) time. The system used was a thin coating layer on a thick substrate layer. The substrates included steel, aluminum, polycarbonate, acrylonitrile-butadiene-styrene (ABS), and Noryl. The coatings included newly developed automotive paints. The four-point bending configuration promoted nice transversed multiple coating cracks on both steel and polymeric substrates. The crosslinked type automotive coatings on steel substrates showed big cracks without microcracks. When theoretical predictions for energy release rate were compared to experimental data for coating/steel substrate samples with multiple cracking, the agreement was good. Crosslinked type coatings on polymeric substrates showed more cracks than theory predicted and the G(sub c)'s were high. Solvent evaporation type coatings on polymeric substrates showed clean multiple cracking and the G(sub c)'s were higher than those obtained by tension analysis of tension experiments with the same substrates. All the polymeric samples showed surface embrittlement after long baking times using four-point bending tests. The most apparent surface embrittlement was observed in the acrylonitrile-butadiene-styrene (ABS) substrate system. The impact properties of coatings as a function of baking time were also investigated. These experiments were performed using an instrumented impact tester. There was a rapid decrease in G(sub c) at short baking times and convergence to a constant value at long baking times. The surface embrittlement conditions and an embrittlement toughness

Effects of ion implantation on the microstructure and residual stress of filter arc CrN films

International Nuclear Information System (INIS)

Weng, K.-W.; Chen, Y.-C.; Han Sheng; Hsu, C.-S.; Chen, Y.-L.; Wang, D.-Y.

2008-01-01

Chromium nitride coatings were deposited using a hybrid physical vapor deposition (PVD) system containing a filter arc deposition (FAD) and a metal plasma ion implantation source (MPII). Exactly how surface residual stress affects film characteristics is investigated using glancing incident X-ray diffraction (GIXRD) and pole figure analyses. Compared with unimplanted CrN, implanted carbon typically increases compressive residual stress and hardness. Wear resistance was also improved by implanted carbon

Coating Properties of WC-Ni Cold Spray Coating for the Application in Secondary Piping System of Nuclear Power Plants

Energy Technology Data Exchange (ETDEWEB)

Kim, JeongWon; Kim, Seunghyun; Kim, Ji Hyun [UNIST, Ulsan (Korea, Republic of)

2015-10-15

As a result of FAC(flow accelerated corrosion), severe accidents, failure of carbon steel like a Mihama Unit-3 occurred. Chemical composition change of carbon steel or coating to inner surface is one of methods to improve corrosion properties. Among them, thermal spray coating is convenient solution to apply at industry. Powder is melted at blast furnace and ejected to substrate. After adhesion, substrate and coating layer is cooled down and coated layer protects steel from corrosion finally. However high thermal energy is transferred to substrate and coating layer so it leads high thermal residual stress in coating procedure. Besides, high temperature for melting powder makes unexpected chemical reaction of powder like an oxidation or carburization. Whereas, cold spray uses low temperature comparing with other thermal spray. Thermal energy is used for not melting powder but high kinetic energy of powder and plastic deformation during collision. Therefore, fuel such as oxygen-acetylene gas is not needed. It needs carrier gas, compressed air, nitrogen or helium, to increase kinetic energy of powder and move powder to substrate. Comparing cold spray with high velocity oxy fuel (HVOF), one of thermal spray, cold spray coating layer contains only WC and Co. One of other problem about WC is brittleness during coating. To improve deformability of WC, binder metal is added. For example, Co, Cr, Ni, Cu, Al, Fe or etc. Additionally, binder metal lowering melting temperature of composite powder increases coating properties. Among them, Co which is widely used as binder metal maintains mechanical properties like a hardness and improves corrosion properties. Therefore Co is not suitable for binder metal of WC coating. In contrast, Ni has better corrosion resistance to alkaline environment and makes lower melting temperature. Moreover, in a view of cold spray, FCC structure has better deformability than BCC or HCP, and BCC has lowest deformability. WC is BCC structure so it

Enhanced Response Speed of ZnO Nanowire Photodetector by Coating with Photoresist

Directory of Open Access Journals (Sweden)

Xing Yang

2016-01-01

Full Text Available Spin-coating photoresist film on ZnO nanowire (NW was introduced into the fabrication procedure to improve photoresponse and recovery speed of a ZnO NW ultraviolet photoelectric detector. A ZnO NW was first assembled on prefabricated electrodes by dielectrophoresis. Then, photoresist was spin-coated on the nanowire. Finally, a metal layer was electrodeposited on the nanowire-electrode contacts. The response properties and I-V characteristics of ZnO NW photodetector were investigated by measuring the electrical current under different conditions. Measurement results demonstrated that the detector has an enhanced photoresponse and recovery speed after coating the nanowire with photoresist. The photoresponse and recovery characteristics of detectors with and without spin-coating were compared to demonstrate the effects of photoresist and the enhancement of response and recovery speed of the photodetector is ascribed to the reduced surface absorbed oxygen molecules and binding effect on the residual oxygen molecules after photoresist spin-coating. The results demonstrated that surface coating may be an effective and simple way to improve the response speed of the photoelectric device.

Chemical reaction engineering studies on cocracking of petroleum vacuum residue with coal, plastics, and biomass (bagasse and petrocrop)

Energy Technology Data Exchange (ETDEWEB)

Ahmaruzzaman, M.; Sharma, D.K. [Indian Institute of Technology, New Delhi (India). Centre for Energy Studies

2007-07-01

This article deals with the studies on cocracking of petroleum vacuum residue (XVR) with thermosetting plastic, I. e., bakelite (BL), Samla coal (SC), biomass, I. e., bagasse (BG) or C. procera (CL) and their binary, ternary, and quaternary mixtures in a thermogravimetric analyzer (TGA). The kinetic studies were performed using the Coats and Redfern kinetic modeling equation. The overall activation energies obtained were 25 kJ/mole for petroleum vacuum residue, 99 kJ/mole for polypropylene, 21 kJ/mole for coal, 23 kJ/mole for Calotropis procera, and 25 kJ/mole for the combination of these four materials. However, other models, such as van Krevelan et al. and Horowitz and Metzger have also been used in some cases to compare the results with those obtained by the Coats and Redfern kinetic models. In the present work, the effect of catalysts on the cracking of Basra vacuum residue (BVR) has also been reported.

Biological Dosimetry of In Vitro Irradiation with Radionuclides : Comparison of Whole Blood, Lymphocyte and Buffy Coat Culture

International Nuclear Information System (INIS)

Kim, Jong Ho; Lee, Dong Soo; Choi, Chang Woon; Chung, June Key; Lee, Myung Chul; Koh, Chang Soon; Kim, Chong Soon; Kim, Hee Geun; Kang, Duck Won; Song, Myung Jae

1995-01-01

The purpose of this study was to establish mononuclear cell cultures such as lymphocytes or buffy coat for the biological dosimetry of in vitro irradiation of the radionuclide Tc-99m in order to exclude the effect of residual doses seen in the cultures of whole blood. Biological dosimetry of Tc-99m on cultured mononuclear cells at doses ranging from 0.05 to 6.00 Gy, by scoring unstable chromosomal aberrations(Ydr) observed in cultured lymphocytes, were performed using peripheral venous blood of healthy normal person. The results showed that; (1) In vitro irradiation of radioisotope in separated lymphocyte or buffy coat showed trace amount af residual doses of isotope after washing. Residual doses of isotopes are increased in proportion tn exposed time and irradiated dose without difference between I-131 anct Tc-99m. (2) We obtained these linear-quadratic dose response equations in lymphocyte and buffy coat culture after in vitro irradiation of Tc-99m, respectively (Ydr = 0,001949 D 2 +0,006279D+ 0.000185; Ydr= 0.002531 D 2 -0.003274 D+0.003488). In conclusion, the linear quadrstic dose response equation from in vitro irradiation of Tc-99m with lymphocyte and buffy coat culture was thought to be useful for assessing Tc-99m indueed biological effects. And mononuclear cell cultures seem to be the most appropriate experimental model for the assessment of biological dosimetry of internal irradiation of radionuclides.

Ammonia volatilization from coated urea forms

Directory of Open Access Journals (Sweden)

Carlos Antonio Costa do Nascimento

2013-08-01

Full Text Available Nitrogen fertilization is a major component of the cost of agricultural production, due to the high cost and low efficiency of fertilizers. In the case of urea, the low efficiency is mainly due to losses by volatilization, which are more pronounced in cultivation systems in which plant residues are left on the soil. The objective of this work was to compare the influence of urea coated with sulfur or boric acid and copper sulfate with conventional N fertilizers on N volatilization losses in sugar cane harvested after stubble burning. The sources urea, sulfur-coated urea, urea coated with boric acid and copper sulfate, as well as nitrate and ammonium sulfate, were tested at amounts containing N rates of 120 kg ha-1 N. The integration of new technologies in urea fertilization can reduce N losses by volatilization. These losses were most reduced when using nitrate and ammonium sulfate. The application of a readily acidified substance (boric acid to urea was more efficient in reducing volatilization losses and nutrient removal by sugar cane than that of a substance with gradual acidification (elemental sulfur.

Failure mechanism for thermal fatigue of thermal barrier coating systems

Energy Technology Data Exchange (ETDEWEB)

Giolli, C.; Scrivani, A.; Rizzi, G. [Turbocoating S.p.A., Rubbiano di Solignano (Italy); Borgioli, F. [Firenze Univ., Sesto Fiorentino (Italy); Bolelli, G.; Lusvarghi, L. [Univ. di Modena e Reggio Emilia, Modena (Italy)

2008-07-01

High temperature thermal fatigue causes the failure of Thermal Barrier Coating (TBC) systems. Due to the difference in thickness and microstructure between thick TBCs and traditional thin TBCs, they cannot be assumed a-priori to possess the same failure mechanisms. Thick TBCs, consisting of a CoNiCrAlY bond coat and Yttria Partially Stabilised Zirconia top coat with different values of porosity, were produced by Air Plasma Spray. Thermal fatigue resistance limit of TBCs was tested by Furnace Cycling Tests (FCT) according to the specifications of an Original Equipment Manufacturer (OEM). TBC systems were analyzed before and after FCT. The morphological and chemical evolution of CoNiCrAlY/TGO microstructure was studied. Sintering effect, residual stress, phase transformation and fracture toughness were evaluated in the ceramic Top Coat. All the tested samples passed FCT according to the specification of an important OEM. Thermal fatigue resistance increases with the amount of porosity in the top coat. The compressive in-plane stresses increase in the TBC systems after thermal cycling, nevertheless the increasing rate has a trend contrary to the porosity level of top coat. The data suggest that the spallation happens at the TGO/Top Coat interface. The failure mechanism of thick TBCs subjected to thermal fatigue was eventually found to be similar to the failure mechanism of thin TBC systems made by APS. (orig.)

Thick sputtered tantalum coatings for high-temperature energy conversion applications

Energy Technology Data Exchange (ETDEWEB)

Stelmakh, Veronika, E-mail: stelmakh@mit.edu; Peykov, Daniel; Chan, Walker R.; Senkevich, Jay J.; Joannopoulos, John D.; Soljačić, Marin; Celanovic, Ivan [Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Castillo, Robert; Coulter, Kent; Wei, Ronghua [Materials Engineering Department, Southwest Research Institute, San Antonio, Texas 78238 (United States)

2015-11-15

Thick sputtered tantalum (Ta) coatings on polished Inconel were investigated as a potential replacement for bulk refractory metal substrates used for high-temperature emitters and absorbers in thermophotovoltaic energy conversion applications. In these applications, high-temperature stability and high reflectance of the surface in the infrared wavelength range are critical in order to sustain operational temperatures and reduce losses due to waste heat. The reflectance of the coatings (8 and 30 μm) was characterized with a conformal protective hafnia layer as-deposited and after one hour anneals at 700, 900, and 1100 °C. To further understand the high-temperature performance of the coatings, the microstructural evolution was investigated as a function of annealing temperature. X-ray diffraction was used to analyze the texture and residual stress in the coatings at four reflections (220, 310, 222, and 321), as-deposited and after anneal. No significant changes in roughness, reflectance, or stress were observed. No delamination or cracking occurred, even after annealing the coatings at 1100 °C. Overall, the results of this study suggest that the thick Ta coatings are a promising alternative to bulk substrates and pave the way for a relatively low-cost and easily integrated platform for nanostructured devices in high-temperature energy conversion applications.

Effect of an absorbent overlay on the residual stress field induced by laser shock processing on aluminum samples

International Nuclear Information System (INIS)

Rubio-Gonzalez, C.; Gomez-Rosas, G.; Ocana, J.L.; Molpeceres, C.; Banderas, A.; Porro, J.; Morales, M.

2006-01-01

Laser shock processing (LSP) or laser shock peening is a new technique for strengthening metals. This process induces a compressive residual stress field, which increases fatigue crack initiation life and reduces fatigue crack growth rate. Specimens of 6061-T6 aluminum alloy are used in this investigation. A convergent lens is used to deliver 2.5 J, 8 ns laser pulses by a Q-switch Nd:YAG laser, operating at 10 Hz. The pulses are focused to a diameter of 1.5 mm onto aluminum samples. Density of 2500 pulses/cm 2 with infrared (1064 nm) radiation was used. The effect of an absorbent overlay on the residual stress field using this LSP setup and this energy level is evaluated. Residual stress distribution as a function of depth is assessed by the hole drilling method. It is observed that the overlay makes the compressive residual stress profile move to the surface. This effect is explained on the basis of the vaporization of the coat layer suppressing thermal effects on the metallic substrate. The effect of coating the specimen surface before LSP treatment may have advantages on improving wear and contact fatigue properties of this aluminum alloy

Neutron diffraction measurements of residual stresses in NPP construction materials

International Nuclear Information System (INIS)

Hinca, R.; Bokuchava, G.

2001-01-01

Neutron diffraction is one of the most powerful methods for condensed matter studies. This method is used for non-destructive determination of residual stresses in material. The fundamental aspects of neutron diffraction are discussed, together with a brief description of the experimental facility. The principal advantage of using neutrons rather than the more conventional X-rays is the fact that neutron can penetrate deeply (2-4 cm for steel and more than 10 cm for aluminium) into metals to determine internal parameters within the bulk of materials. We present results of measurements residual stresses in NPP construction material - austenitic stainless steel (Cr-18%, Ni-10%, Ti-1%) coated with high-nickel alloy. (authors)

Analysis and measurement of residual stress distribution of vanadium/ceramics joints for fusion reactor applications

International Nuclear Information System (INIS)

Nemoto, Y.; Ueda, K.

1998-01-01

Vanadium alloys are considered as candidate structural materials for fusion reactor system. When vanadium alloys are used in fusion reactor system, joining with ceramics for insulating is one of material issues to be solved to make component of fusion reactor. In the application of ceramics/metal jointing and coating, residual stress caused by difference of thermal expansion rate between ceramics and metals is an important factor in obtaining good bonding strength and soundness of coating. In this work, residual stress distribution in direct diffusion bonded vanadium/alumina joint (jointing temperature: 1400 C) was measured by small area X-ray diffraction method. And the comparison of finite element method (FEM) analysis and actual stress distribution was carried out. Tensile stress concentration at the edge of the boundary of the joint in alumina was observed. The residual stress concentration may cause cracks in alumina, or failure of bonding. Actually, cracks in alumina caused by thermal stress after bonding at 1500 C was observed. The stress concentration of the joint must be reduced to obtain good bonded joint. Lower bonding temperature or to devise the shape of the outer surface of the joint will reduce the stress concentration. (orig.)

Corrosion protection by organic coatings in gas and oil industry

International Nuclear Information System (INIS)

Hussain, A.

2008-01-01

The drive to improve performance of coatings as protection against corrosion for automotive, aerospace and oil and gas industries is a never-ending story. Surface preparation is the most important single factor when a substrate surface e.g. steel is to be protected with a coating. This implies an extremely accurate and reliable characterisation of the substrate-surface prior to coating process and the investigation of polymeric coating materials. In order to have a durable adhesive bonding between the polymeric coating materials and the substrate i.e. to ensure prolonged life time and fewer maintenance intervals of coated products, a pre-treatment of the substrate is required in many cases. Sand blasting, corona /plasma pre.treatment of the substrate and the use of coupling agents like organo silanes are well accepted recent methods. Advanced surface analytical techniques like ESCA and TOFSIMS are proving to be extremely helpful in the chemical characterisation of the substrate surface. Contamination e.g. fat residues, tensides etc. on the substrate is one of the most serious enemies of adhesive bonding and the above mentioned techniques are playing a vital role in combating the enemy. Modern thermal analytical methods have made tremendous contribution to the development and quality control of high-performance polymeric coatings. MDSC, DMA and DETA are proving to be very useful tools for the characterisation of high-performance coating materials. An in-depth understanding of the structure-property relationship of these materials, predominantly epoxy and polyurethane coating systems, is a pre-requisite for their successful application and subsequent Quality Control. (author)

High temperature glass thermal control structure and coating. [for application to spacecraft reusable heat shielding

Science.gov (United States)

Stewart, D. A.; Goldstein, H. E.; Leiser, D. B. (Inventor)

1983-01-01

A high temperature stable and solar radiation stable thermal control coating is described which is useful either as such, applied directly to a member to be protected, or applied as a coating on a re-usable surface insulation (RSI). It has a base coat layer and an overlay glass layer. The base coat layer has a high emittance, and the overlay layer is formed from discrete, but sintered together glass particles to give the overlay layer a high scattering coefficient. The resulting two-layer space and thermal control coating has an absorptivity-to-emissivity ratio of less than or equal to 0.4 at room temperature, with an emittance of 0.8 at 1200 F. It is capable of exposure to either solar radiation or temperatures as high as 2000 F without significant degradation. When used as a coating on a silica substrate to give an RSI structure, the coatings of this invention show significantly less reduction in emittance after long term convective heating and less residual strain than prior art coatings for RSI structures.

Approaches to investigate delamination and interfacial toughness in coated systems: an overview

International Nuclear Information System (INIS)

Chen Jinju; Bull, S J

2011-01-01

The fundamental property which often dictates the performance of a coating is its adhesion to the substrate and thus there are many techniques to measure adhesion. The choice of methods is dependent on many factors such as the mechanical properties of the coating and substrate, the interface properties, the microstructure of the coating/substrate system, residual stress, coating thickness and the intended application. Most tests aim to introduce a stable interfacial crack and make it propagate under controlled conditions and model this process to determine adhesion. The corresponding models are either stress analysis-based or energy-based. With the advent of miniature systems and very thin functional coatings, there is a need for characterization of adhesion at small length scales and some specific tests have been developed which are not appropriate for thicker coatings. Among these, indentation and scratch methods have the widest range of applicability but it is necessary to analyse the failure mechanisms before choosing an appropriate model to extract adhesion parameters. This paper reviews the main quantitative adhesion tests for coatings and highlights the tests which can be used to assess submicrometre coatings and thin films. The paper also highlights the modelling and analysis methods necessary to extract reliable adhesion properties illustrating this with examples for submicrometre coatings on silicon and architectural glass.

On Degradation of Cast Iron Surface-Protective Paint Coat Joint

Directory of Open Access Journals (Sweden)

Tupaj M.

2016-09-01

Full Text Available The paper is a presentation of a study on issues concerning degradation of protective paint coat having an adverse impact on aesthetic qualities of thin-walled cast-iron castings fabricated in furan resin sand. Microscopic examination and microanalyses of chemistry indicated that under the coat of paint covering the surface of a thin-walled casting, layers of oxides could be found presence of which can be most probably attributed to careless cleaning of the casting surface before the paint application process, as well as corrosion pits evidencing existence of damp residues under the paint layers contributing to creation of corrosion micro-cells

Influence of SiC coating thickness on mechanical properties of SiCf/SiC composite

Science.gov (United States)

Yu, Haijiao; Zhou, Xingui; Zhang, Wei; Peng, Huaxin; Zhang, Changrui

2013-11-01

Silicon carbide (SiC) coatings with varying thickness (ranging from 0.14 μm to 2.67 μm) were deposited onto the surfaces of Type KD-I SiC fibres with native carbonaceous surface using chemical vapour deposition (CVD) process. Then, two dimensional SiC fibre reinforced SiC matrix (2D SiCf/SiC) composites were fabricated using polymer infiltration and pyrolysis (PIP) process. Influences of the fibre coating thickness on mechanical properties of SiC fibre and SiCf/SiC composite were investigated using single-filament test and three-point bending test. The results indicated that flexural strength of the composites initially increased with the increasing CVD SiC coating thickness and reached a peak value of 363 MPa at the coating thickness of 0.34 μm. Further increase in the coating thickness led to a rapid decrease in the flexural strength of the composites. The bending modulus of composites showed a monotonic increase with increasing coating thickness. A chemical attack of hydrogen or other ions (e.g. a C-H group) on the surface of SiC fibres during the coating process, owing to the formation of volatile hydrogen, lead to an increment of the surface defects of the fibres. This was confirmed by Wang et al. [35] in their work on the SiC coating of the carbon fibre. In the present study, the existing ˜30 nm carbon on the surface of KD-I fibre [36] made the fibre easy to be attacked. Deposition of non-stoichiometric SiC, causing a decrease in strength. During the CVD process, a small amount of free silicon or carbon always existed [35]. The existence of free silicon, either disordered the structure of SiC and formed a new source of cracks or attacked the carbon on fibre surface resulting in properties degeneration of the KD-I fibre. The effect of residual stress. The different thermal expansion coefficient between KD-I SiC fibre and CVD SiC coating, which are 3 × 10-6 K-1 (RT ˜ 1000 °C) and 4.6 × 10-6 K-1 (RT ˜ 1000 °C), respectively, could cause residual stress

Development of nanostructured PVD coatings for total knee replacement joints using HIPIMS

Science.gov (United States)

Sugumaran, Arunprabhu A.

The aim of this study was to develop thin film coatings for total knee replacement joints using high power impulse magnetron sputtering (HIPIMS). An industrial size four cathode magnetron sputtering system equipped with direct current (DC) and HIPIMS power supplies was used for this purpose. Initially, Plasma diagnostics were carried out using optical emission spectroscopy (OES) while sputtering Ti target in Ar + N2 atmosphere by utilizing various HIP IMS/conventional DCMS (henceforth UBM) source combinations by varying the process parameters such as coil current and N2 flow. Then, single layer titanium nitride (TiN) coating was deposited by varying the degree of HIPIMS utilisation and the process parameters such as bias voltage and coil current to thoroughly understand the effect of degree of HIPIMS utilisation on the microstructure, residual stress, texture, mechanical, tribological and corrosion properties of such coatings. The degree of HIPIMS utilisation was altered by increasing the number of HIPIMS targets used for the deposition. Four different source combinations were used for this purpose, as follows: 4 cathodes in conventional DCMS mode to deposit pure UBM coating, 1 HIPIMS + 3UBM and 2HIPIMS + 2UBM cathodes to deposit combined HIPIMS/UBM coatings and 2HIPIMS cathodes to deposit pure HIPIMS coatings. TiN/NbN, TiCN/NbCN and CrN/NbN multilayer coatings were deposited on CoCr alloy test buttons along with other (HSS, SS and Si) substrates since our intended application is on total knee replacement joints made of CoCr alloy. The knowledge gained by investigating the TiN (Ar + N[2]) plasma and the properties of TiN was used to determine the process parameters for depositing the multilayer coatings. X- ray diffraction (XRD) technique was used for calculating the texture, residual stress and bilayer thickness of the coatings. Nanoindentation method was used to determine the nano hardness of the coatings. The adhesion strength of the coatings was estimated by

Thin coatings for heavy industry: Advanced coatings for pipes and valves

Science.gov (United States)

Vernhes, Luc

investigation of an HVOF 80/20 Cr 3C2-NiCr coating failure in an on-off metal-seated ball valve (MSBV) used in supercritical steam lines in a power plant, along with an assessment of alternative coating solutions that are less susceptible to this failure mode. HVOF 80/20 Cr3C2-NiCr coating has been used to protect thousands of MSBVs without incident. However, in this case the valves were challenged with exposure to rapid variations in high-pressure flow and temperature, resulting in a unique situation that caused the coating to undergo cracking and cohesive failure. Carbide precipitation was found to be a major factor, resulting in coating embrittlement. Reduced coating toughness and ductility allowed thermal, mechanical, and residual stresses to initiate cracks and propagate them more easily, leading to coating failure with exposure to thermal shock. To alleviate these issues, possible coating alternatives were assessed. The third article presents the mechanical, tribological, and corrosion properties of two novel hybrid coating systems: 1) a tungsten-tungsten carbide (W-WC) top layer and a laser cladded cobalt-chromium (Co-Cr) interlayer (StelliteRTM 6 superalloy) applied to a 316 stainless steel substrate; and 2) the same W-WC top layer and an HVOF spray-and-fused Ni-W-Cr-B interlayer (ColmonoyRTM 88 superalloy) applied to an InconelRTM 718 substrate. X-ray diffraction, energy dispersive spectroscopy, and scanning electron microscopy were used to analyze the microstructure of the coating layers. Microindentation was used to measure surface hardness and the hardness profile of the coating systems. Rockwell indentation was used to assess coating adhesion according to CEN/TS 1071-8. Surface load-carrying capacity was also assessed by measuring micro- and macrohardness at high loads. Tribological properties were assessed with a linear reciprocating ball-on-flat sliding wear test, and corrosion resistance was measured by potentiodynamic polarization and electrochemical impedance

Thermal Expansion of Vacuum Plasma Sprayed Coatings

Science.gov (United States)

Raj, S V.; Palczer, A. R.

2010-01-01

Metallic Cu-8%Cr, Cu-26%Cr, Cu-8%Cr-1%Al, NiAl and NiCrAlY monolithic coatings were fabricated by vacuum plasma spray deposition processes for thermal expansion property measurements between 293 and 1223 K. The corrected thermal expansion, (DL/L(sub 0) varies with the absolute temperature, T, as (DL/L(sub 0) = A(T - 293)(sup 3) + BIT - 293)(sup 2) + C(T - 293) + D, where, A, B, C and D are thermal, regression constants. Excellent reproducibility was observed for all of the coatings except for data obtained on the Cu-8%Cr and Cu-26%Cr coatings in the first heat-up cycle, which deviated from those determined in the subsequent cycles. This deviation is attributed to the presence of residual stresses developed during the spraying of the coatings, which are relieved after the first heat-up cycle. In the cases of Cu-8%Cr and NiAl, the thermal expansion data were observed to be reproducible for three specimens. The linear expansion data for Cu-8% Cr and Cu-26%Cr agree extremely well with rule of mixture (ROM) predictions. Comparison of the data for the Cu-8%Cr coating with literature data for Cr and Cu revealed that the thermal expansion behavior of this alloy is determined by the Cu-rich matrix. The data for NiAl and NiCrAlY are in excellent agreement with published results irrespective of composition and the methods used for processing the materials. The implications of these results on coating GRCop-84 copper alloy combustor liners for reusable launch vehicles are discussed.

Surface modification of polyamide thin film composite membrane by coating of titanium dioxide nanoparticles

Directory of Open Access Journals (Sweden)

Thu Hong Anh Ngo

2016-12-01

Full Text Available In this paper, the coating of TiO2 nanoparticles onto the surface of a polyamide thin film composite nanofiltration membrane has been studied. Changes in the properties and separation performance of the modified membranes were systematically characterized. The experimental results indicated that the membrane surface hydrophilicity was significantly improved by the presence of the coated TiO2 nanoparticles with subsequent UV irradiation. The separation performance of the UV-irradiated TiO2-coated membranes was improved with a great enhancement of flux and a very high retention for removal of residual dye in an aqueous feed solution. The antifouling property of the UV-irradiated TiO2-coated membranes was enhanced with higher maintained flux ratios and lower irreversible fouling factors compared with an uncoated membrane.

Temperature dependence of the residual stresses and mechanical properties in TiN/CrN nano-layered coatings processed by cathodic arc deposition

International Nuclear Information System (INIS)

Lomello, F.; Arab Pour Yazdi; Sanchette, F.; Schuster, F.; Tabarant, M.; Billard, A.

2014-01-01

Nano-layered TiN-CrN coatings were synthesized by cathodic arc deposition (CAD) on M2 tool steel substrates. The aim of this study was to establish a double-correlation between the influence of the bilayer period and the deposition temperature on the resulting mechanical-tribological properties. The superlattice hardening enhancement was observed in samples deposited at different temperatures - i.e. without additional heating, 300 C and 400 C. Nonetheless, the residual compressive stresses are believed to be the responsible for reducing the hardness enhancement when the deposition temperature was increased. For instance, sample deposited without additional heating presented a hardness of 48.5 ± 1.3 GPa, while by increasing the processing temperature up to 400 C it was reduced down to 31.2 ± 4.1 GPa due to the stress relaxation. Indeed, the sample deposited at low temperature which possesses the thinnest bilayer period (13 nm) exhibited better mechanical properties. On the contrary, the role of the interfaces introduced when the period is decreased seems to rule the wear resistance. (authors)

Microstructures and Properties of Laser Cladding Al-TiC-CeO2 Composite Coatings

Science.gov (United States)

Kong, Dejun; Song, Renguo

2018-01-01

Al-TiC-CeO2 composite coatings have been prepared by using a laser cladding technique, and the microstructure and properties of the resulting composite coatings have been investigated using scanning electron microscopy (SEM), a 3D microscope system, X-ray diffraction (XRD), micro-hardness testing, X-ray stress measurements, friction and wear testing, and an electrochemical workstation. The results showed that an Al-Fe phase appears in the coatings under different applied laser powers and shows good metallurgical bonding with the matrix. The dilution rate of the coating first decreases and then increases with increasing laser power. The coating was transformed from massive and short rod-like structures into a fine granular structure, and the effect of fine grain strengthening is significant. The microhardness of the coatings first decreases and then increases with increasing laser power, and the maximum microhardness can reach 964.3 HV0.2. In addition, the residual stress of the coating surface was tensile stress, and crack size increases with increasing stress. When the laser power was 1.6 kW, the coating showed high corrosion resistance. PMID:29373555

Influence of substrate temperature on properties of MgF2 coatings

International Nuclear Information System (INIS)

Yu Hua; Qi Hongji; Cui Yun; Shen Yanming; Shao Jianda; Fan Zhengxiu

2007-01-01

Thermal boat evaporation was employed to prepare MgF 2 single-layer coatings upon both JGS1 and UBK7 substrates at different substrate temperatures. Microstructure, transmittance and residual stress of these coatings were measured by X-ray diffraction, spectrophotometer, and optical interferometer, respectively. Measurement of laser induced damage threshold (LIDT) of the samples was performed at 355 nm, 8 ns pulses. The results showed that high substrate temperature was beneficial to crystallization of the film. Above 244 deg. C, the refractive index increased gradually with the substrate temperature rising. Whereas, it was exceptional at 210 deg. C that the refractive index was higher than those deposited at 244 and 277 deg. C. The tensile residual stresses were exhibited in all MgF 2 films, but not well correlated with the substrate temperature. In addition, the stresses were comparatively smaller upon JGS1 substrates. A tendency could be seen that the LIDTs reached the highest values at about 244 deg. C, and the films upon JGS1 had higher LIDTs than those upon UBK7 substrates at the same temperature. Meanwhile, the damage morphologies showed that the laser damage of the coating resulted from an absorbing center at the film-substrate interface. The features of the damages were displayed by an absorbing center dominated model. Furthermore, the reason of the difference in LIDT values was discussed in detail

Calculated efficiencies of three-material low stress coatings for diffractive x-ray transmission optics

International Nuclear Information System (INIS)

Kubec, Adam; Braun, Stefan; Gawlitza, Peter; Menzel, Maik; Leson, Andreas

2016-01-01

Diffractive X-ray optical elements made by thin film coating techniques such as multilayer Laue lenses (MLL) and multilayer zone plates (MZP) are promising approaches to achieve resolutions in hard X-ray microscopy applications of less than 10 nm. The challenge is to make a lens with a large numerical aperture on the one hand and a decent working distance on the other hand. One of the limiting factors with the coated structures is the internal stress in the films, which can lead to significant bending of the substrate and various types of unwanted diffraction effects. Several approaches have been discussed to overcome this challenge. One of these is a three-material combination such as Mo/MoSi_2/Si, where four single layers per period are deposited. Mo and Si represent the absorber and spacer in this case while MoSi_2 forms a diffusion barrier; in addition the thicknesses of absorber and spacer are chosen to minimize residual stress of the overall coating. Here the diffraction efficiency as well as the profile of the beam in the focal plane are discussed in order to find a tradeoff between lowest residual stress and best diffraction properties.

Thermogravimetric investigation of the co-combustion between the pyrolysis oil distillation residue and lignite.

Science.gov (United States)

Li, Hao; Xia, Shuqian; Ma, Peisheng

2016-10-01

Co-combustion of lignite with distillation residue derived from rice straw pyrolysis oil was investigated by non-isothermal thermogravimetric analysis (TGA). The addition of distillation residue improved the reactivity and combustion efficiency of lignite, such as increasing the weight loss rate at peak temperature and decreasing the burnout temperature and the total burnout. With increasing distillation residue content in the blended fuels, the synergistic interactions between distillation residue and lignite firstly increased and then decreased during co-combustion stage. Results of XRF, FTIR, (13)C NMR and SEM analysis indicated that chemical structure, mineral components and morphology of samples have great influence on the synergistic interactions. The combustion mechanisms and kinetic parameters were calculated by the Coats Redfern model, suggesting that the lowest apparent activation energy (120.19kJ/mol) for the blended fuels was obtained by blending 60wt.% distillation residue during main co-combustion stage. Copyright © 2016 Elsevier Ltd. All rights reserved.

In vitro evaluation of whole faba bean and its seed coat as a potential source of functional food components.

Science.gov (United States)

Çalışkantürk Karataş, Selen; Günay, Demet; Sayar, Sedat

2017-09-01

In vitro studies were conducted to evaluate the particular nutritional benefits of whole faba bean seed (WFB) and fava bean seed coat (FBSC). Total dietary fiber contents of WFB and FBSC were 27.5% and 82.3%, respectively. FBSC were contained much higher total phenolic substances, condensed tannins, and total antioxidant activity than WFB. Bile acid (BA)-binding capacities of in vitro digested samples and nutritionally important products produced by in vitro fermentation of digestion residues were also studied. The BA-binding capacities of WFB and FBSC were 1.94 and 37.50μmol/100mg, respectively. Total BA bound by FBSC was even higher than the positive standard cholestyramine. Lignin and other constituents of the Klason residue were found to influence BA-binding properties. Moreover, the extent of the in vitro fermentation process showed that, fermentability of FBSC residue was significantly lower than that of WFB residue. Overall, faba bean, especially its seed coat, has great potential as a functional food. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis of cuprous oxide epoxy nanocomposite as an environmentally antimicrobial coating.

Science.gov (United States)

M El Saeed, Ashraf; Abd El-Fattah, M; Azzam, Ahmed M; Dardir, M M; Bader, Magd M

2016-08-01

Cuprous oxide is commonly used as a pigment; paint manufacturers begin to employ cuprous oxide as booster biocides in their formulations, to replace the banned organotins as the principal antifouling compounds. Epoxy coating was reinforced with cuprous oxide nanoparticles (Cu2O NPs). The antibacterial as well as antifungal activity of Cu2O epoxy nanocomposite (Cu2O EN) coating films was investigated. Cu2O NPs were also experimented for antibiofilm and time-kill assay. The thermal stability and the mechanical properties of Cu2O EN coating films were also investigated. The antimicrobial activity results showed slowdown, the growth of organisms on the Cu2O EN coating surface. TGA results showed that incorporating Cu2O NPs into epoxy coating considerably enhanced the thermal stability and increased the char residue. The addition of Cu2O NPs at lower concentration into epoxy coating also led to an improvement in the mechanical resistance such as scratch and abrasion. Cu2O NPs purity was confirmed by XRD. The TEM photograph demonstrated that the synthesized Cu2O NPs were of cubic shape and the average diameter of the crystals was around 25nm. The resulting perfect dispersion of Cu2O NPs in epoxy coating revealed by SEM ensured white particles embedded in the epoxy matrix. Copyright © 2016 Elsevier B.V. All rights reserved.

Plasma-Sprayed Hydroxylapatite-Based Coatings: Chemical, Mechanical, Microstructural, and Biomedical Properties

Science.gov (United States)

Heimann, Robert B.

2016-06-01

This contribution discusses salient properties and functions of hydroxylapatite (HA)-based plasma-sprayed coatings, including the effect on biomedical efficacy of coating thickness, phase composition and distribution, amorphicity and crystallinity, porosity and surface roughness, cohesion and adhesion, micro- and nano-structured surface morphology, and residual coating stresses. In addition, it will provide details of the thermal alteration that HA particles undergo in the extremely hot plasma jet that leads to dehydroxylated phases such as oxyhydroxylapatite (OHA) and oxyapatite (OA) as well as thermal decomposition products such as tri-(TCP) and tetracalcium phosphates (TTCP), and quenched phases such as amorphous calcium phosphate (ACP). The contribution will further explain the role of ACP during the in vitro interaction of the as-deposited coatings with simulated body fluid resembling the composition of extracellular fluid (ECF) as well as the in vivo responses of coatings to the ECF and the host tissue, respectively. Finally, it will briefly describe performance profiles required to fulfill biological functions of osteoconductive bioceramic coatings designed to improve osseointegration of hip endoprostheses and dental root implants. In large parts, the content of this contribution is a targeted review of work done by the author and his students and coworkers over the last two decades. In addition, it is considered a stepping stone toward a standard operation procedure aimed at depositing plasma-sprayed bioceramic implant coatings with optimum properties.

Fire resistance properties of ceramic wool fiber reinforced intumescent coatings

Energy Technology Data Exchange (ETDEWEB)

Amir, N., E-mail: norlailiamir@petronas.com.my; Othman, W. M. S. W., E-mail: wamosa@gmail.com; Ahmad, F., E-mail: faizahmad@petronas.com.my [Mechanical Engineering Department, Universiti Teknologi PETRONAS Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

2015-07-22

This research studied the effects of varied weight percentage and length of ceramic wool fiber (CWF) reinforcement to fire retardant performance of epoxy-based intumescent coating. Ten formulations were developed using ammonium polyphosphate (APP), expandable graphite (EG), melamine (MEL) and boric acid (BA). The mixing was conducted in two stages; powdered materials were grinded in Rocklabs mortar grinder and epoxy-mixed using Caframo mixer at low speed mixing. The samples were applied on mild steel substrate and exposed to 500°C heat inside Carbolite electric furnace. The char expansion and its physical properties were observed. Scanning electron microscopy (SEM) analyses were conducted to inspect the fiber dispersion, fiber condition and the cell structure of both coatings and chars produced. Thermogravimetric analyses (TGA) were conducted to study the thermal properties of the coating such as degradation temperature and residual weight. Fire retardant performance was determined by measuring backside temperature of substrate in 1-hour, 1000°C Bunsen burner test according to UL 1709 fire regime. The results showed that intumescent coating reinforced with CWF produced better fire resistance performance. When compared to unreinforced coating, formulation S6-15 significantly reduced steel temperature at approximately 34.7% to around 175°C. However, higher fiber weight percentage had slightly decreased fire retardant performance of the coating.

Fire resistance properties of ceramic wool fiber reinforced intumescent coatings

International Nuclear Information System (INIS)

Amir, N.; Othman, W. M. S. W.; Ahmad, F.

2015-01-01

This research studied the effects of varied weight percentage and length of ceramic wool fiber (CWF) reinforcement to fire retardant performance of epoxy-based intumescent coating. Ten formulations were developed using ammonium polyphosphate (APP), expandable graphite (EG), melamine (MEL) and boric acid (BA). The mixing was conducted in two stages; powdered materials were grinded in Rocklabs mortar grinder and epoxy-mixed using Caframo mixer at low speed mixing. The samples were applied on mild steel substrate and exposed to 500°C heat inside Carbolite electric furnace. The char expansion and its physical properties were observed. Scanning electron microscopy (SEM) analyses were conducted to inspect the fiber dispersion, fiber condition and the cell structure of both coatings and chars produced. Thermogravimetric analyses (TGA) were conducted to study the thermal properties of the coating such as degradation temperature and residual weight. Fire retardant performance was determined by measuring backside temperature of substrate in 1-hour, 1000°C Bunsen burner test according to UL 1709 fire regime. The results showed that intumescent coating reinforced with CWF produced better fire resistance performance. When compared to unreinforced coating, formulation S6-15 significantly reduced steel temperature at approximately 34.7% to around 175°C. However, higher fiber weight percentage had slightly decreased fire retardant performance of the coating

Fire resistance properties of ceramic wool fiber reinforced intumescent coatings

Science.gov (United States)

Amir, N.; Othman, W. M. S. W.; Ahmad, F.

2015-07-01

This research studied the effects of varied weight percentage and length of ceramic wool fiber (CWF) reinforcement to fire retardant performance of epoxy-based intumescent coating. Ten formulations were developed using ammonium polyphosphate (APP), expandable graphite (EG), melamine (MEL) and boric acid (BA). The mixing was conducted in two stages; powdered materials were grinded in Rocklabs mortar grinder and epoxy-mixed using Caframo mixer at low speed mixing. The samples were applied on mild steel substrate and exposed to 500°C heat inside Carbolite electric furnace. The char expansion and its physical properties were observed. Scanning electron microscopy (SEM) analyses were conducted to inspect the fiber dispersion, fiber condition and the cell structure of both coatings and chars produced. Thermogravimetric analyses (TGA) were conducted to study the thermal properties of the coating such as degradation temperature and residual weight. Fire retardant performance was determined by measuring backside temperature of substrate in 1-hour, 1000°C Bunsen burner test according to UL 1709 fire regime. The results showed that intumescent coating reinforced with CWF produced better fire resistance performance. When compared to unreinforced coating, formulation S6-15 significantly reduced steel temperature at approximately 34.7% to around 175°C. However, higher fiber weight percentage had slightly decreased fire retardant performance of the coating.

Tribological performance of an H-DLC coating prepared by PECVD

Science.gov (United States)

Solis, J.; Zhao, H.; Wang, C.; Verduzco, J. A.; Bueno, A. S.; Neville, A.

2016-10-01

Carbon-based coatings are of wide interest due to their application in machine elements subjected to continuous contact where fluid lubricant films are not permitted. This paper describes the tribological performance under dry conditions of duplex layered H-DLC coating sequentially deposited by microwave excited plasma enhanced chemical vapour deposition on AISI 52100 steel. The architecture of the coating comprised Cr, WC, and DLC (a-C:H) with a total thickness of 2.8 μm and compressive residual stress very close to 1 GPa. Surface hardness was approximately 22 GPa and its reduced elastic modulus around 180 GPa. Scratch tests indicated a well adhered coating achieving a critical load of 80 N. The effect of normal load on the friction and wear behaviours were investigated with steel pins sliding against the actual coating under dry conditions at room temperature (20 ± 2 °C) and 35-50% RH. The results show that coefficient of friction of the coating decreased from 0.21 to 0.13 values with the increase in the applied loads (10-50 N). Specific wear rates of the surface coating also decrease with the increase in the same range of applied loads. Maximum and minimum values were 14 × 10-8 and 5.5 × 10-8 mm-3/N m, respectively. Through Raman spectroscopy and electron microscopy it was confirmed the carbon-carbon contact, due to the tribolayer formation on the wear scars of the coating and pin. In order to further corroborate the experimental observations regarding the graphitisation behaviour, the existing mathematical relationships to determine the graphitisation temperature of the coating/steel contact as well as the flash temperature were used.

Influence of Cu Content on the Microstructure and Mechanical Properties of Cr-Cu-N Coatings

Directory of Open Access Journals (Sweden)

Ji Cheng Ding

2018-01-01

Full Text Available The Cr-Cu-N coatings with various Cu contents (0–25.18 (±0.17 at.% were deposited on Si wafer and stainless steel (SUS 304 substrates in reactive Ar+N2 gas mixture by a hybrid coating system combining pulsed DC and RF magnetron sputtering techniques. The influence of Cu content on the coating composition, microstructure, and mechanical properties was investigated. The microstructure of the coatings was significantly altered by the introduction of Cu. The deposited coatings exhibit solid solution structure with different compositions in all of the samples. Addition of Cu is intensively favored for preferred orientation growth along (200 direction by restricting in (111 direction. With increasing Cu content, the surface and cross-sectional morphology of coatings were changed from triangle cone-shaped, columnar feature to broccoli-like and compact glassy microstructure, respectively. The mechanical properties including the residual stress, nanohardness, and toughness of the coatings were explored on the basis of Cu content. The highest hardness was obtained at the Cu content of 1.49 (±0.10 at.%.

The novel silicon-containing epoxy/PEPA phosphate flame retardant for transparent intumescent fire resistant coating

Energy Technology Data Exchange (ETDEWEB)

Shi, Yanchao [School of Materials Science and Engineering, Tongji University, 4800 Cao' an Road, Shanghai 201804 (China); Wang, Guojian, E-mail: wanggj@tongji.edu.cn [School of Materials Science and Engineering, Tongji University, 4800 Cao' an Road, Shanghai 201804 (China); Key Laboratory of Advanced Civil Engineering Materials, Ministry of Education, 4800 Cao' an Road, Shanghai 201804 (China)

2016-11-01

an important protecting role for the inner char residue and improved the fire protection of the coatings. TGA result demonstrated that silicon enhanced the thermo-oxidation resistance of coatings efficiently. Furthermore, real-time FTIR revealed the intumescent process of the fire resistant coatings according to the chemical structure changes of char residue.

The Influence of Nanodispersed Modifiers on the Structure and Properties of Plasma-Sprayed Coatings

Directory of Open Access Journals (Sweden)

Igor V. Smirnov

2017-10-01

Full Text Available Background. Currently, plasma-sprayed coatings are widely used to protect machine parts operating under conditions of high loads and temperatures, abrasive wear and exposure to corrosive media. Objective. The aim of the paper is to improve the physico-mechanical characteristics of plasma-sprayed coatings by modification of nano-sized particles of TiO2 oxides compounds. Methods. Experimental studies of corrosion resistance, microhardness, adhesion strength and residual stresses of plasma-sprayed coatings based on the oxide aluminum ceramic powder with the addition of nanodisperse TiO2 powder were conducted. Results. It is found that addition of TiO2 nanodisperse modifier to the oxide aluminum ceramic powder composition leads to corrosion resistance increase 2.8 times in a 10 % hydrochloric acid solution. The adhesive strength of ceramic nanomodified coatings is increased by 15–20 %. Conclusions. The positive influence of nanodispersed powders on the physico-mechanical and tribological characteristics of plasma-sprayed coatings is established.

Polyurethane Organosilicate Nanocomposites as Blood Compatible Coatings

Directory of Open Access Journals (Sweden)

Johnson H. Y. Chung

2012-02-01

Full Text Available Polymer clay nanocomposites (NCs show remarkable potential in the field of drug delivery due to their enhanced barrier properties. It is hypothesised that well dispersed clay particles within the polymer matrix create a tortuous pathway for diffusing therapeutic molecules, thereby resulting in more sustained release of the drug. As coatings for medical devices, these materials can simultaneously modulate drug release and improve the mechanical performance of an existing polymer system without introducing additional materials with new chemistries that can lead to regulatory concerns. In this study, polyurethane organosilicate nanocomposites (PUNCs coated onto stainless steel wires were evaluated for their feasibility as blood compatible coatings and as drug delivery systems. Heparin was selected as the model drug to examine the impact of silicate loading and modifier chain length in modulating release. Findings revealed that better dispersion was achieved from samples with lower clay loadings and longer alkyl chains. The blood compatibility of PUNCs as assessed by thrombin generation assays showed that the addition of silicate particles did not significantly decrease the thrombin generation lag time (TGT, p = 0.659 or the peak thrombin (p = 0.999 of polyurethane (PU. PUNC coatings fabricated in this research were not cytotoxic as examined by the cell growth inhibition assay and were uniformly intact, but had slightly higher growth inhibition compared to PU possibly due to the presence of organic modifiers (OM. The addition of heparin into PUNCs prolonged the TGT, indicating that heparin was still active after the coating process. Cumulative heparin release profiles showed that the majority of heparin released was from loosely attached residues on the surface of coils. The addition of heparin further prolonged the TGT as compared to coatings without added heparin, but a slight decrease in heparin activity was observed in the NCs

Thermally joining and/or coating or thermally separating the workpieces having heat-sensitive coating, comprises restoring coating by thermally coating the coating material after thermally joining and/or coating or thermally separating

OpenAIRE

Riedel, Frank; Winkelmann, Ralf; Puschmann, Markus

2011-01-01

The method for thermally joining and/or coating or thermally separating the workpieces (1), which have a heat-sensitive coating (2), comprises restoring the coating by thermally coating a coating material (3) after thermally joining and/or coating or thermally separating the workpieces. A part of the thermal energy introduced in the workpiece for joining and/or coating or separating or in the workpieces is used for thermally coating the coating material. Two workpieces are welded or soldered ...

Corrosion and Fatigue Behavior of High-Strength Steel Treated with a Zn-Alloy Thermo-diffusion Coating

Science.gov (United States)

Mulligan, C. P.; Vigilante, G. N.; Cannon, J. J.

2017-11-01

High and low cycle fatigue tests were conducted on high-strength steel using four-point bending. The materials tested were ASTM A723 steel in the as-machined condition, grit-blasted condition, MIL-DTL-16232 heavy manganese phosphate-coated condition, and ASTM A1059 Zn-alloy thermo-diffusion coated (Zn-TDC). The ASTM A723 steel base material exhibits a yield strength of 1000 MPa. The effects of the surface treatments versus uncoated steel were examined. The fatigue life of the Zn-TDC specimens was generally reduced on as-coated specimens versus uncoated or phosphate-coated specimens. Several mechanisms are examined including the role of compressive residual stress relief with the Zn-TDC process as well as fatigue crack initiation from the hardened Zn-Fe alloy surface layer produced in the gas-metal reaction. Additionally, the effects of corrosion pitting on the fatigue life of coated specimens are explored as the Zn-TDC specimens exhibit significantly improved corrosion resistance over phosphate-coated and oiled specimens.

CrAlN coating to enhance the power loss and magnetostriction in grain oriented electrical steel

Directory of Open Access Journals (Sweden)

Vishu Goel

2016-05-01

Full Text Available Grain oriented electrical steels (GOES are coated with aluminium orthophosphate on top of a forsterite (Mg2SiO4 layer to provide stress and insulation resistance to reduce the power loss and magnetostriction. In this work Chromium Aluminium Nitride (CrAlN was coated on GOES samples with electron beam physical vapour deposition and was tested in the single strip and magnetostriction tester to measure the power loss and magnetostriction before and after coating. Power loss was reduced by 2% after coating and 6 % post annealing at 800 °C. For applied compressive stress of 6 MPa, the magnetostrictive strain was zero with the CrAlN coating as compared to 22 and 24 μϵ for fully finished GOES and GOES without phosphate coating. The thickness of the coating was found to be 1.9 ± 0.2 μm estimated with Glow Discharge Optical Emission Spectroscopy (GDOES. The magnetic domain imaging showed domain narrowing after coating. The reduction in power loss and magnetostriction was due to the large residual compressive stress and Young’s modulus (270 GPa of the coating.

CrAlN coating to enhance the power loss and magnetostriction in grain oriented electrical steel

Energy Technology Data Exchange (ETDEWEB)

Goel, Vishu; Anderson, Philip; Hall, Jeremy [Wolfson Centre for Magnetics, Cardiff University, Cardiff- CF243AA (United Kingdom); Robinson, Fiona [Cogent power Ltd., Newport-NP190RB (United Kingdom); Bohm, Siva [Dept. of metallurgical engineering & materials science, IIT Bombay, Mumbai-400076 (India)

2016-05-15

Grain oriented electrical steels (GOES) are coated with aluminium orthophosphate on top of a forsterite (Mg{sub 2}SiO{sub 4}) layer to provide stress and insulation resistance to reduce the power loss and magnetostriction. In this work Chromium Aluminium Nitride (CrAlN) was coated on GOES samples with electron beam physical vapour deposition and was tested in the single strip and magnetostriction tester to measure the power loss and magnetostriction before and after coating. Power loss was reduced by 2% after coating and 6 % post annealing at 800 °C. For applied compressive stress of 6 MPa, the magnetostrictive strain was zero with the CrAlN coating as compared to 22 and 24 μϵ for fully finished GOES and GOES without phosphate coating. The thickness of the coating was found to be 1.9 ± 0.2 μm estimated with Glow Discharge Optical Emission Spectroscopy (GDOES). The magnetic domain imaging showed domain narrowing after coating. The reduction in power loss and magnetostriction was due to the large residual compressive stress and Young’s modulus (270 GPa) of the coating.

Investigations on antibody binding to a micro-cantilever coated with a BAM pesticide residue

DEFF Research Database (Denmark)

Bache, Michael; Taboryski, Rafael Jozef; Schmid, Silvan

2011-01-01

-BAM antibody is measured using the CantiLab4© system from Cantion A/S with four gold-coated cantilevers and piezo resistive readout. The detection mechanism is in principle label-free, but fluorescent-marked antibodies have been used to subsequently verify the binding on the cantilever surface. The bending...

Salmon Muscle Adherence to Polymer Coatings and Determination of Antibiotic Residues by Reversed-Phase High-Performance Liquid Chromatography Coupled to Selected Reaction Monitoring Mass Spectrometry, Atomic Force Microscopy, and Fourier Transform Infrared Spectroscopy

Directory of Open Access Journals (Sweden)

E. Zumelzu

2015-01-01

Full Text Available The persistent adhesion of salmon muscle to food container walls after treatment with urea solution was observed. This work evaluated the diffusion of antibiotics from the salmon muscle to the polyethylene terephthalate (PET coating protecting the electrolytic chromium coated steel (ECCS plates. New aquaculture production systems employ antibiotics such as florfenicol, florfenicol amine, oxytetracycline, and erythromycin to control diseases. The introduction of antibiotics is a matter of concern regarding the effects on human health and biodiversity. It is important to determine their impact on the adhesion of postmortem salmon muscle to can walls and the surface and structural changes affecting the functionality of multilayers. This work characterized the changes occurring in the multilayer PET polymer and steel of containers by electron microscopy, 3D atomic force microscopy (3D-AFM, X-ray photoelectron spectroscopy (XPS, and Fourier transform infrared spectroscopy (FT-IR analyses. A robust mass spectrometry methodology was employed to determine the presence of antibiotic residues. No evidence of antibiotics was observed on the protective coating in the range between 0.001 and 2.0 ng/mL; however, the presence of proteins, cholesterol, and alpha-carotene was detected. This in-depth profiling of the matrix-level elements is relevant for the use of adequate materials in the canning export industry.

Thermal performance of glass fiber reinforced intumescent fire retardant coating for structural applications

Energy Technology Data Exchange (ETDEWEB)

Ahmad, Faiz, E-mail: faizahmad@petronas.com.my; Ullah, Sami; Aziz, Hammad, E-mail: engr.hammad.aziz03@gmail.com; Omar, Nor Sharifah [Department of Mechanical Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, Tronoh 31750 Perak (Malaysia)

2015-07-22

The results of influence of glass fiber addition into the basic intumescent coating formulation towards the enhancement of its thermal insulation properties are presented. The intumescent coatings were formulated from expandable graphite, ammonium polyphosphate, melamine, boric acid, bisphenol A epoxy resin BE-188, polyamide amine H-2310 hardener and fiberglass (FG) of length 3.0 mm. Eight intumescent formulations were developed and the samples were tested for their fire performance by burning them at 450°C, 650°C and 850°C in the furnace for two hours. The effects of each fire test at different temperatures; low and high temperature were evaluated. Scanning Electron Microscope, X-Ray Diffraction technique and Thermo Gravimetric Analysis were conducted on the samples to study the morphology, the chemical components of char and the residual weight of the coatings. The formulation, FG08 containing 7.0 wt% glass fiber provided better results with enhanced thermal insulation properties of the coatings.

Manufacturing inspection of electrical steels using Magnetic Barkhausen Noise: residual stress detection

Energy Technology Data Exchange (ETDEWEB)

Samimi, A.A., E-mail: 9aa8@queensu.ca [Queen' s Univ., Applied Magnetics Group, Kingston, Ontario (Canada); Krause, T.W. [Royal Military College of Canada, NDE Lab., Kingston, Ontario (Canada); Clapham, L. [Queen' s Univ., Applied Magnetics Group, Kingston, Ontario (Canada); Gallaugher, M.; Ding, Y.; Chromik, R. [McGill Univ., Dept. of Mining and Materials Engineering, Montreal, Quebec (Canada)

2016-09-15

Non-oriented Electrical Steel (NOES) is the magnetic core lamination material used for flux transfer in rotary machines. The presence of residual stress associated with material processing may be detrimental to magnetic domain structure refinement and as a result, magnetic performance of NOES. Therefore, manufacturing inspection of NOES that identifies the presence of residual stress could contribute to the production of more energy efficient cores. However, standard materials evaluation is limited to destructive and off-line techniques. The present work employed Magnetic Barkhausen Noise (MBN) for nondestructive identification of local residual stress associated with stages in material processing. Analysis of MBN from single strips of NOES demonstrated clear response to applied tensile stress, mechanical shearing, the presence of an insulating coating and punching. The results establish the potential of MBN as a nondestructive testing technology for quality control of electrical steels at various stages of manufacture. (author)

High-field thermal transports properties of REBCO coated conductors

CERN Document Server

Bonura, M

2015-01-01

The use of REBCO coated conductors is envisaged for many applications, extending from power cables to high-field magnets. Whatever the case, thermal properties of REBCO tapes play a key role for the stability of superconducting devices. In this work, we present the first study on the longitudinal thermal conductivity (k) of REBCO coated conductors in magnetic fields up to 19 T applied both parallelly and perpendicularly to the thermal-current direction. Copper-stabilized tapes from six industrial manufacturers have been investigated. We show that zero-field k of coated conductors can be calculated with an accuracy of ‡ 15% from the residual resistivity ratio of the stabilizer and the Cu/non-Cu ratio. Measurements performed at high fields have allowed us to evaluate the consistency of the procedures generally used for estimating in-field k in the framework of the Wiedemann-Franz law from an electrical characterization of the materials. In-field data are intended to provide primary ingredients for the ...

Mechanical Performance of Cold-Sprayed A357 Aluminum Alloy Coatings for Repair and Additive Manufacturing

Science.gov (United States)

Petráčková, K.; Kondás, J.; Guagliano, M.

2017-12-01

Cold-sprayed coatings made of A357 aluminum alloy, a casting alloy widely used in aerospace, underwent set of standard tests as well as newly developed fatigue test to gain an information about potential of cold spray for repair and additive manufacturing of loaded parts. With optimal spray parameters, coating deposition on substrate with smooth surface resulted in relatively good bonding, which can be further improved by application of grit blasting on substrate's surface. However, no enhancement of adhesion was obtained for shot-peened surface. Process temperature, which was set either to 450 or 550 °C, was shown to have an effect on adhesion and cohesion strength, but it does not influence residual stress in the coating. To assess cold spray perspectives for additive manufacturing, flat tensile specimens were machined from coating and tested in as-sprayed and heat-treated (solution treatment and aging) condition. Tensile properties of the coating after the treatment correspond to properties of the cast A357-T61 aluminum alloy. Finally, fatigue specimen was proposed to test overall performance of the coating and coating's fatigue limit is compared to the results obtained on cast A357-T61 aluminum alloy.

A preferential coating technique for fabricating large, high quality optics

International Nuclear Information System (INIS)

Alcock, S.G.; Cockerton, S.

2010-01-01

A major challenge facing optic manufacturers is the fabrication of large mirrors (>1 m) with minimal residual slope errors (<0.5 μrad rms). We present a differential coating method with the potential to satisfy such exacting technical demands. Iterative cycles of measurement using the Diamond-NOM, followed by preferential deposition, were performed on a 1200 mm long, silicon mirror. The applied coatings were observed to reduce the optical slope and figure errors from 1.62 to 0.44 μrad rms, and from 208 to 13 nm rms, respectively. It is hoped that this research will lead to commercially available products, of direct benefit to the Synchrotron, Free Electron Laser, Astronomy, Space, and Laser communities, who all require state-of-the-art optics.

Fracture toughness and sliding properties of magnetron sputtered CrBC and CrBCN coatings

Science.gov (United States)

Wang, Qianzhi; Zhou, Fei; Ma, Qiang; Callisti, Mauro; Polcar, Tomas; Yan, Jiwang

2018-06-01

CrBC and CrBCN coatings with low and high B contents were deposited on 316L steel and Si wafers using an unbalanced magnetron sputtering system. Mechanical properties including hardness (H), elastic modulus (E) and fracture toughness (KIc) as well as residual stresses (σ) were quantified. A clear correlation between structural, mechanical and tribological properties of coatings was found. In particular, structural analyses indicated that N incorporation in CrBC coatings with high B content caused a significant structural evolution of the nanocomposite structure (crystalline grains embedded into an amorphous matrix) from nc-CrB2/(a-CrBx, a-BCx) to nc-CrN/(a-BCx, a-BN). As a result, the hardness of CrBC coating with high B content decreased from 23.4 to 16.3 GPa but the fracture toughness was enhanced. Consequently, less cracks initiated on CrBCN coatings during tribological tests, which combined with the shielding effect of a-BN on wear debris, led to a low friction coefficient and wear rate.

Deposition and characterization of plasma sprayed Ni-5A1/ magnesia stabilized zirconia based functionally graded thermal barrier coating

International Nuclear Information System (INIS)

Baig, M N; Khalid, F A

2014-01-01

Thermal barrier coatings (TBCs) are employed to protect hot section components in industrial and aerospace gas turbine engines. Conventional TBCs frequently fail due to high residual stresses and difference between coefficient of thermal expansion (CTE) of the substrate and coatings. Functionally graded thermal barrier coatings (FG-TBCs) with gradual variation in composition have been proposed to minimize the problem. In this work, a five layered functionally graded thermal barrier coating system was deposited by atmospheric plasma spray (APS) technique on Nimonic 90 substrates using Ni-5Al as bond coat (BC) and magnesia stabilized zirconia as top coat (TC). The coatings were characterized by SEM, EDS, XRD and optical profilometer. Microhardness and coefficient of thermal expansion of the five layers deposited as individual coatings were also measured. The deposited coating system was oxidized at 800°C. SEM analysis showed that five layers were successfully deposited by APS to produce a FG-TBC. The results also showed that roughness (Ra) of the individual layers decreased with an increase in TC content in the coatings. It was found that microhardness and CTE values gradually changed from bond coat to cermet layers to top coat. The oxidized coated sample revealed parabolic behavior and changes in the surface morphology and composition of coating

Behaviour of glass and thermal protective coatings on stainless steels in the nitrogen tetroxide based coolant

International Nuclear Information System (INIS)

Bakalin, Yu.I.; Dobrunova, V.M.; Doroshkevich, V.N.; Nesterenko, V.B.; Trubnikov, V.P.

1985-01-01

The technology of application of glass and enamel protective coatings on stainless steel has been examined, their testing in the medium of nitrogen tetroxide based coolant with different content of nitric acid has been carried out, the basic characteristics of the coatings after testing have been defined. Chromium-nickel austenitic 12kh18n10t steel, widely used in the nuclear power, have been chosen as a basic object of examination. The coatings have been tested in nitrogen oxide at P=12.0 MPa, temperature 310 deg C and 0.1% HNO 3 , and also in the medium of vat residue of the rectifying tower with nitric acid content up to 25 mass %. Tests of the coatings have demonstrated their sufficiently high stability, especially of those based on enamels A-20 and BK-5. These coatings are characterised by satisfactory performance and can be used for corrosion protection of the materials used in nuclear power

Thermal properties and flame retardancy of an ether-type UV-cured polyurethane coating

Directory of Open Access Journals (Sweden)

2010-09-01

Full Text Available A new UV-reactive monomer piperazine-N,N′-bis(acryloxyethylaryl-phosphoramidate (N-PBAAP containing phosphorus and nitrogen was synthesized and used as flame retardant for an ether-type UV-cured polyurethane acrylate (PUA coating. The thermal properties of the PUA films were investigated by thermogravimetric analysis (TGA in air and nitrogen atmosphere. The TGA results showed that the incorporation of N-PBAAP can obviously enhance the char residue of the PUA coatings. From the TGA and real time Fourier transformed infrared spectroscopy (RT-FTIR results, different degradation behaviors were observed in the PUA coatings with different N-PBAAP content. The combustibility of the PUA coatings was evaluated by microscale combustion calorimeter (MCC. The MCC results revealed that the addition of NPBAAP in the coatings can significantly reduce the peak Heat Release Rate (pHRR, Heat Release Capacity (HRC and the Total Heat Release (THR of the samples. Furthermore, dynamical mechanical thermal analysis (DMA was employed to examine the viscoelastic properties of the PUA films. It was found that the incorporation of N-PBAAP in the formulation can bring in more functional groups to the coatings, which results in an increase of the glass transition temperature (Tg and cross linking density (XLD of the films.

Prediction of protein-protein interactions in dengue virus coat proteins guided by low resolution cryoEM structures

Directory of Open Access Journals (Sweden)

Srinivasan Narayanaswamy

2010-06-01

Full Text Available Abstract Background Dengue virus along with the other members of the flaviviridae family has reemerged as deadly human pathogens. Understanding the mechanistic details of these infections can be highly rewarding in developing effective antivirals. During maturation of the virus inside the host cell, the coat proteins E and M undergo conformational changes, altering the morphology of the viral coat. However, due to low resolution nature of the available 3-D structures of viral assemblies, the atomic details of these changes are still elusive. Results In the present analysis, starting from Cα positions of low resolution cryo electron microscopic structures the residue level details of protein-protein interaction interfaces of dengue virus coat proteins have been predicted. By comparing the preexisting structures of virus in different phases of life cycle, the changes taking place in these predicted protein-protein interaction interfaces were followed as a function of maturation process of the virus. Besides changing the current notion about the presence of only homodimers in the mature viral coat, the present analysis indicated presence of a proline-rich motif at the protein-protein interaction interface of the coat protein. Investigating the conservation status of these seemingly functionally crucial residues across other members of flaviviridae family enabled dissecting common mechanisms used for infections by these viruses. Conclusions Thus, using computational approach the present analysis has provided better insights into the preexisting low resolution structures of virus assemblies, the findings of which can be made use of in designing effective antivirals against these deadly human pathogens.

Mirrors for High Resolution X-Ray Optics---Figure Preserving IR/PT Coating

Science.gov (United States)

Chan, Kai-Wing; Olsen, Lawrence; Sharpe, Marton; Numata, Ai; McClelland, Ryan; Saha, Timo; Zhang, Will

2016-01-01

Coating stress of 10 - 20 nm of Ir is sufficiently high to distort the figure of arc-second thin lightweight mirrors. For iridium: --Stress sigma 4 GPa for 15 nm film implies 60 Nm integrated stress-- Need less than 3 N/m (or stress less than 200 MPa) for sub-arcsecond optics. Basic Approaches for Mitigation. A. Annealing the film-- Glass can be heat up to 400 C without distortion. Silicon is even more resistant.-- It was found that recovery is limited by residual thermal stress from taking the mirror down from high T. B. Coating bi-layer films with compressive stress with tensile stress. C. Front-and-back coating with magnetron sputtering or atomic layer deposition-- Sputtering involve spanning of substrates. Geometric difference in setup (convexness/concaveness of curved mirrors) does not permit precise front-and-back matching-- Atomic layer deposition can provide a uniform deposition front and back simultaneously.

European coatings conference - Marine coatings. Proceedings

Energy Technology Data Exchange (ETDEWEB)

NONE

2008-07-01

This volume contains 13 lectures (manuscripts or powerpoint foils) with the following topics: 1. Impact of containerization on polyurethane and polyurea in marine and protective coatings (Malte Homann); 2. The application of combinatorial/high-throughput methods to the development of marine coatings (Bret Chisholm); 3. Progress and perspectives in the AMBIO (advanced nanostructured surfaces for the control of biofouling) Project (James Callow); 4. Release behaviour due to shear and pull-off of silicone coatings with a thickness gradient (James G. Kohl); 5. New liquid rheology additives for high build marine coatings (Andreas Freytag); 6. Effective corrosion protection with polyaniline, polpyrrole and polythiophene as anticorrosice additives for marine paints (Carlos Aleman); 7. Potential applications of sol gel technology for marine applications (Robert Akid); 8: Performance of biocide-free Antifouling Coatings for leisure boats (Bernd Daehne); 9. Novel biocidefree nanostructured antifouling coatings - can nano do the job? (Corne Rentrop); 10. One component high solids, VOC compliant high durability finish technology (Adrian Andrews); 11. High solid coatings - the hybrid solution (Luca Prezzi); 12. Unique organofunctional silicone resins for environmentally friendly high-performance coatings (Dieter Heldmann); 13. Silicone-alkyd paints for marine applications: from battleship-grey to green (Thomas Easton).

Characterization of Solids in Residual Wastes from Single-Shell Tanks at the Hanford Site, Washington, USA - 9277

International Nuclear Information System (INIS)

Krupka, Kenneth M.; Cantrell, Kirk J.; Schaef, Herbert T.; Arey, Bruce W.; Heald, Steve M.; Deutsch, William J.; Lindberg, Michael J.

2009-01-01

Solid-phase characterization methods have been used in an ongoing study of residual wastes (i.e., waste remaining after final retrieval operations) from the underground single-shell storage tanks 241-C-103, 241-C-106, 241-C-202, 241-C-203, and 241-S-112 at the U.S. Department of Energy's Hanford Site in Washington State. The results of studies completed to date show significant variability in the compositions of those residual wastes and the compositions, morphologies, and crystallinities of the individual phases that make up these wastes. These differences undoubtedly result from the various waste types stored and transferred in and out each tank and the sluicing and retrieval operations used for waste retrieval. Our studies indicate that these residual wastes are chemically-complex assemblages of crystalline and amorphous solids that contain contaminants as discrete phases and/or co-precipitated within oxide phases. Depending on the specific tank, various solids (e.g., gibbsite; boehmite; dawsonite; cancrinite; Fe oxides such as hematite, goethite, and maghemite; rhodochrosite; lindbergite; whewellite; nitratine; and numerous amorphous or poorly crystalline phases) have been identified by X-ray diffraction and scanning electron microscopy/energy dispersive X-ray spectroscopy in residual wastes studied to date. Our studies also show that contact of residual wastes with Ca(OH)2- and CaCO3-saturated aqueous solutions, which were used as surrogates for the compositions of pore-fluid leachants derived from young and aged cements respectively, may alter the compositions of solid phases present in the contacted wastes. Fe oxides/hydroxides have been identified in all residual wastes studied to date. They occur in these wastes as discrete particles, particles intergrown within a matrix of other phases, and surface coatings on other particles or particle aggregates. These Fe oxides/hydroxides typically contain trace concentrations of other transition metals, such Cr, Mn

Effects of WC phase contents on the microstructure, mechanical properties and tribological behaviors of WC/a-C superlattice coatings

Energy Technology Data Exchange (ETDEWEB)

Pu, Jibin [Key Laboratory of Marine Materials and Related Technologies, Key Laboratory of Marine Materials and Protective Technologies of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); He, Dongqing [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100039 (China); Wang, Liping, E-mail: lpwang@licp.cas.cn [Key Laboratory of Marine Materials and Related Technologies, Key Laboratory of Marine Materials and Protective Technologies of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

2015-12-01

Graphical abstract: - Highlights: • WC/a-C superlattice coatings were synthesized with various WC phase content. • Superlattice structure diminished residual stress and densified microstructure. • Nanocomposite coating with W 5.43 at.% achieved the optimal tribological properties. • Friction triggered WO{sub 3} lead to a low friction coefficient at 200 °C. - Abstract: Nanocomposite WC/a-C coatings with variable contents of tungsten carbide (WC{sub 1−x}) and amorphous carbon (a-C) were successfully fabricated using a magnetron sputtering process. The microstructure, mechanical properties and tribological behaviors of the as-fabricated coatings were investigated and compared. The results showed that the “superlattice coating” feature of an alternating multilayer structure with a-C and WC{sub 1−x} nanocrystallites layers on the nanoscale was formed. These multilayer superlattice structures led to diminished residual stress and improved the strength of the adhesion to the substrate. The WC/a-C coating with W 5.43 at.% exhibited low friction coefficients of 0.05 at 25 °C and 0.28 at 200 °C. This significant improvement in the tribological performances of the WC/a-C coating was mainly attributed to the superior “superlattice” microstructure and the formation of a continuously compacted tribofilms, which was rich in graphitized carbon at 25 °C and dominated by the friction triggered WO{sub 3} at 200 °C. Moreover, the WC/a-C coating with W 5.43 at.% achieved optimal anti-wear properties at 25 °C due to the synergistic combination of the enhancement effects of the WC{sub 1−x} nanoparticles and the partition effect from the transfer film that restricted direct contact of the steel ball with the coating and thus prevented further intense wear. The accelerated wear of the WC/a-C coating with the increase of the WC phase content at 200 °C might be due to the combination of oxidation wear and abrasive wear that originated from the WC{sub 1−x} phase.

Platelet storage lesion in interim platelet unit concentrates: A comparison with buffy-coat and apheresis concentrates.

Science.gov (United States)

Singh, Sukhi; Shams Hakimi, Caroline; Jeppsson, Anders; Hesse, Camilla

2017-12-01

Platelet storage lesion is characterized by morphological changes and impaired platelet function. The collection method and storage medium may influence the magnitude of the storage lesion. The aim of this study was to compare the newly introduced interim platelet unit (IPU) platelet concentrates (PCs) (additive solution SSP+, 40% residual plasma content) with the more established buffy-coat PCs (SSP, 20% residual plasma content) and apheresis PCs (autologous plasma) in terms of platelet storage lesions. Thirty PCs (n=10 for each type) were assessed by measuring metabolic parameters (lactate, glucose, and pH), platelet activation markers, and in vitro platelet aggregability on days 1, 4, and 7 after donation. The expression of platelet activation markers CD62p (P-selectin), CD63 (LAMP-3), and phosphatidylserine was measured using flow cytometry and in vitro aggregability was measured with multiple electrode aggregometry. Higher platelet activation and lower in vitro aggregability was observed in IPU than in buffy-coat PCs on day 1 after donation. In contrast, metabolic parameters, expression of platelet activation markers, and in vitro aggregability were better maintained in IPU than in buffy-coat PCs at the end of the storage period. Compared to apheresis PCs, IPU PCs had higher expression of activation markers and lower in vitro aggregability throughout storage. In conclusion, the results indicate that there are significant differences in platelet storage lesions between IPU, buffy-coat, and apheresis PCs. The quality of IPU PCs appears to be at least comparable to buffy-coat preparations. Further studies are required to distinguish the effect of the preparation methods from storage conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Determining the effect of cartridge case coatings on GSR using post-fire priming cup residue.

Science.gov (United States)

Terry, Molly; Fookes, Barry; Bridge, Candice M

2017-07-01

Ammunition is typically composed of a lead-based priming mixture which contributes to the characteristics most commonly used for the identification of gunshot residue (GSR). Due to the health risks often associated with lead, the use of lead-free primers in ammunitions is becoming more popular. Thus, the presence of GSR is becoming more difficult to discern based on the traditional means, i.e. the presence of lead (Pb), barium (Ba), and antimony (Sb). While research has been conducted on the differences between lead-based and lead-free muzzle discharge residue, few have researched other components of ammunition which may lead to other means of characterizing GSR. This research, therefore, covers that gap by focusing on the priming cup present in ammunition and the residue which may originate from it, that can contribute to muzzle discharge residue. In this study, a lead-based and a lead-free ammunition from four different manufacturers were chosen. The cartridges were fired using a Glock 17, 9mm Parabellum, collected post-fire, and subsequently de-primed resulting in the removal of the anvil. The GSR present on the anvils and cups was analyzed using scanning electron microscopy coupled with energy dispersive x-ray spectrometry (SEM-EDX). The data was then processed using unit vector analysis for normalization and analyzed using principal component analysis (PCA) and linear discriminant analysis (LDA). This data was then used to determine the components of the cartridge case which contribute to GSR and develop a method of characterization between lead-free and lead-based ammunition. Such a method will improve the detection of GSR by strengthening the criteria of identification. Copyright © 2017 Elsevier B.V. All rights reserved.

Oxidation resistance of TiN, CrN, TiAlN and CrAlN coatings deposited by lateral rotating cathode arc

International Nuclear Information System (INIS)

Chim, Y.C.; Ding, X.Z.; Zeng, X.T.; Zhang, S.

2009-01-01

In this paper, four kinds of hard coatings, TiN, CrN, TiAlN and CrAlN (with Al/Ti or Al/Cr atomic ratio around 1:1), were deposited on stainless steel substrates by a lateral rotating cathode arc technique. The as-deposited coatings were annealed in ambient atmosphere at different temperatures (500-1000 o C) for 1 h. The evolution of chemical composition, microstructure, and microhardness of these coatings after annealing at different temperatures was systematically analyzed by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and nanoindentation experiments. The oxidation behaviour and its influence on overall hardness of these four coatings were compared. It was found that the ternary TiAlN and CrAlN coatings have better oxidation resistance than their binary counterparts, TiN and CrN coatings. The Cr-based coatings (CrN and CrAlN) exhibited evidently better oxidation resistance than the Ti-based coatings (TiN and TiAlN). TiN coating started to oxidize at 500 o C. After annealing at 700 o C no N could be detected by EDX, indicating that the coating was almost fully oxidized. After annealed at 800 o C, the coating completely delaminated from the substrate. TiAlN started to oxidize at 600 o C. It was nearly fully oxidized (with little residual nitrogen detected in the coating by EDX) and partially delaminated at 1000 o C. Both CrN and CrAlN started to oxidize at 700 o C. CrN was almost fully oxidized (with little residual nitrogen detected in the coating by EDX) and partially delaminated at 900 o C. The oxidation rate of the CrAlN coating is quite slow. After annealing at 1000 o C, only about 19 at.% oxygen was detected and the coating showed no delamination. The Ti-based (TiN and TiAlN) coatings were not able to retain their hardness at higher temperatures (≥ 700 o C). On the other hand, the hardness of CrAlN was stable at a high level between 33 and 35 GPa up to an annealing temperature of 800 o C and still kept at a comparative high value of

ELABORATION OF AN EPOXY COATING REINFORCED WITH ZIRCONIUM CARBIDE NANOSTRUCTURES

Directory of Open Access Journals (Sweden)

Lucia G. Díaz-Barriga

2013-12-01

Full Text Available This work shows the preparation of a transparent epoxy coating reinforced with 200 PPM of zirconium carbide nanostructures. The nanostructures of ZrC were prepared by mechanosynthesis. The additive characteristics analyzed by X-ray diffraction (XRD and scanning electron microscopy (SEM were presented. Epoxy coating adhesion on a steel plate was analyzed using MEB. Thermogravimetric analysis (TGA was performed to the reinforced paints between 20-700 °C. The reinforced enamel was compared with an enamel without nanostructures. There is not vaporization of reinforced enamel at a 95 y 100 °C with ZrC particles size of 10 µm y 120 nm respectively. The final enamel degradation is slower when there is a 14% by weight of the residue and 426 °C with 120nm diameter particles.

Evidence for lysine acetylation in the coat protein of a polerovirus.

Science.gov (United States)

Cilia, Michelle; Johnson, Richard; Sweeney, Michelle; DeBlasio, Stacy L; Bruce, James E; MacCoss, Michael J; Gray, Stewart M

2014-10-01

Virions of the RPV strain of Cereal yellow dwarf virus-RPV were purified from infected oat tissue and analysed by MS. Two conserved residues, K147 and K181, in the virus coat protein, were confidently identified to contain epsilon-N-acetyl groups. While no functional data are available for K147, K181 lies within an interfacial region critical for virion assembly and stability. The signature immonium ion at m/z 126.0919 demonstrated the presence of N-acetyllysine, and the sequence fragment ions enabled an unambiguous assignment of the epsilon-N-acetyl modification on K181. We hypothesize that selection favours acetylation of K181 in a fraction of coat protein monomers to stabilize the capsid by promoting intermonomer salt bridge formation.

Nanoparticle/Polymer Nanocomposite Bond Coat or Coating

Science.gov (United States)

Miller, Sandi G.

2011-01-01

This innovation addresses the problem of coatings (meant to reduce gas permeation) applied to polymer matrix composites spalling off in service due to incompatibility with the polymer matrix. A bond coat/coating has been created that uses chemically functionalized nanoparticles (either clay or graphene) to create a barrier film that bonds well to the matrix resin, and provides an outstanding barrier to gas permeation. There is interest in applying clay nanoparticles as a coating/bond coat to a polymer matrix composite. Often, nanoclays are chemically functionalized with an organic compound intended to facilitate dispersion of the clay in a matrix. That organic modifier generally degrades at the processing temperature of many high-temperature polymers, rendering the clay useless as a nano-additive to high-temperature polymers. However, this innovation includes the use of organic compounds compatible with hightemperature polymer matrix, and is suitable for nanoclay functionalization, the preparation of that clay into a coating/bondcoat for high-temperature polymers, the use of the clay as a coating for composites that do not have a hightemperature requirement, and a comparable approach to the preparation of graphene coatings/bond coats for polymer matrix composites.

Characterization of diamond-like carbon coatings prepared by pulsed bias cathodic vacuum arc deposition

International Nuclear Information System (INIS)

Wu Jinbao; Chang, J.-J.; Li, M.-Y.; Leu, M.-S.; Li, A.-K.

2007-01-01

Hydrogen free diamond-like carbon (DLC) coatings have been deposited on Si(100) and stainless steel substrates by cathodic vacuum arc plasma deposition with pulse voltage. Adherent deposits on silicon can be obtained through applying gradient Ti/TiC/DLC layers. A pulse bias of - 100 V was applied to the substrate in order to obtain a denser structure of DLC coating approximately 1 μm thick. The microstructure and hardness value of DLC films were analyzed by using X-ray photoelectron spectroscopy and nano-indenter. The experimental results show that the duty cycle strongly influenced the hardness and sp 3 content of the DLC coatings. We observed that when the duty cycle was raised from 2.5% to 12.5%, the hardness increased from 26 GPa to 49 GPa, and the sp 3 fraction of the DLC films measured by XPS increased from 39% to 50.8 % as well. But at constant duty cycle, say 12.5%, the hardness is dropped from 49 to 14 GPa in proportion to the increase of residual gas pressure from 3 x 10 -3 Pa to 1 Pa. As the residual gas pressure increased, collisional phenomenon will decrease the energy of the ions. Ions with low energy make more graphitic carbon links and result in a low hardness value

Thermal barrier coatings application in diesel engines

Science.gov (United States)

Fairbanks, J. W.

1995-01-01

Commercial use of thermal barrier coatings in diesel engines began in the mid 70's by Dr. Ingard Kvernes at the Central Institute for Industrial Research in Oslo, Norway. Dr. Kvernes attributed attack on diesel engine valves and piston crowns encountered in marine diesel engines in Norwegian ships as hot-corrosion attributed to a reduced quality of residual fuel. His solution was to coat these components to reduce metal temperature below the threshold of aggressive hot-corrosion and also provide protection. Roy Kamo introduced thermal barrier coatings in his 'Adiabatic Diesel Engine' in the late 70's. Kamo's concept was to eliminate the engine block water cooling system and reduce heat losses. Roy reported significant performance improvements in his thermally insulated engine at the SAE Congress in 1982. Kamo's work stimulates major programs with insulated engines, particularly in Europe. Most of the major diesel engine manufacturers conducted some level of test with insulated combustion chamber components. They initially ran into increased fuel consumption. The German engine consortium had Prof. Woschni of the Technical Institute in Munich. Woschni conducted testing with pistons with air gaps to provide the insulation effects. Woschni indicated the hot walls of the insulated engine created a major increase in heat transfer he refers to as 'convection vive.' Woschni's work was a major factor in the abrupt curtailment of insulated diesel engine work in continental Europe. Ricardo in the UK suggested that combustion should be reoptimized for the hot-wall effects of the insulated combustion chamber and showed under a narrow range of conditions fuel economy could be improved. The Department of Energy has supported thermal barrier coating development for diesel engine applications. In the Clean Diesel - 50 Percent Efficient (CD-50) engine for the year 2000, thermal barrier coatings will be used on piston crowns and possibly other components. The primary purpose of the

A sensitive monoclonal antibody-based enzyme-linked immunosorbent assay for chlorpyrifos residue determination in Chinese agricultural smaples

Science.gov (United States)

A monoclonal antibody-based competitive antibody-coated enzyme-linked immunosorbent assay (ELISA) was developed and optimized for determining chlorpyrifos residue in agricultural products. The IC50 and IC10 of this ELISA were 3.3 ng/mL and 0.1 ng/mL respectively. The average recoveries recovery rate...

Residual nilpotence and residual solubility of groups

International Nuclear Information System (INIS)

Mikhailov, R V

2005-01-01

The properties of the residual nilpotence and the residual solubility of groups are studied. The main objects under investigation are the class of residually nilpotent groups such that each central extension of these groups is also residually nilpotent and the class of residually soluble groups such that each Abelian extension of these groups is residually soluble. Various examples of groups not belonging to these classes are constructed by homological methods and methods of the theory of modules over group rings. Several applications of the theory under consideration are presented and problems concerning the residual nilpotence of one-relator groups are considered.

Effects of cathode pulse at high frequency on structure and composition of Al2TiO5 ceramic coatings on Ti alloy by plasma electrolytic oxidation

International Nuclear Information System (INIS)

Yao Zhongping; Liu Yunfu; Xu Yongjun; Jiang Zhaohua; Wang Fuping

2011-01-01

Research highlights: → Al 2 TiO 5 in the coating on Ti alloy by PEO treatment changes with the increase of the cathode pulse, regardless of the amount and the grain size. → The cathode pulse brings about the decrease of γ-Al 2 O 3 and the increase of rutile TiO 2 in the coating. → The appropriate cathode pulse during PEO process is beneficial to reduce residual discharging channels and improve the density of the coating. - Abstract: The aim of this work is to investigate the effects of cathode pulse under high working frequency on structure and composition of ceramic coatings on Ti-6Al-4V alloys by plasma electrolytic oxidation (PEO). Ceramic coatings were prepared on Ti alloy by pulsed bi-polar plasma electrolytic oxidation in NaAlO 2 solution. The phase composition, morphology and element distribution in the coating were investigated by X-ray diffractometry, scanning electron microscopy and energy distribution spectroscopy, respectively. The coating was mainly composed of a large amount of Al 2 TiO 5 . As the cathode pulse was increased, the amount and grain size of Al 2 TiO 5 were first increased, and then decreased. γ-Al 2 O 3 in the coating was gradually decreased to nothing with the increase in the cathode pulse whereas rutile TiO 2 began to form in the coating. As opposed to the single-polar anode pulse mode, the cathode pulse reduced the thickness of the coatings. However, as the cathode pulse intensity continued to increase, the coating then became thicker regardless of cathode current density or pulse width. In addition, the residual discharging channels were reduced and the density of the coating was increased with the appropriate increase of the cathode pulse.

Recent Advances in the Deposition of Diamond Coatings on Co-Cemented Tungsten Carbides

Directory of Open Access Journals (Sweden)

R. Polini

2012-01-01

Full Text Available Co-cemented tungsten carbides, namely, hard metals are largely used to manufacture high wear resistant components in several manufacturing segments. Coating hard metals with superhard materials like diamond is of utmost interest as it can further extend their useful lifespan. The deposition of diamond coatings onto WC-Co can be extremely complicated as a result of poor adhesion. This can be essentially ascribed to (i the mismatch in thermal expansion coefficients between diamond and WC-Co, at the typical high temperatures inside the chemical vapour deposition (CVD chamber, generates large residual stresses at the interface; (ii the role of surface Co inside the WC-Co matrix during diamond CVD, which promotes carbon dissolution and diffusion. The present investigation reviews the techniques by which Co-cemented tungsten carbides can be treated to make them prone to receive diamond coatings by CVD. Further, it proposes interesting ecofriendly and sustainable alternatives to further improve the diamond deposition process as well as the overall performance of the coated hard metals.

Spin-coating: A new approach for improving dispersion of cellulose nanocrystals and mechanical properties of poly (lactic acid) composites.

Science.gov (United States)

Shojaeiarani, Jamileh; Bajwa, Dilpreet S; Stark, Nicole M

2018-06-15

This study systematically evaluated the influence of masterbatch preparation techniques, solvent casting and spin-coating methods, on composite properties. Composites were manufactured by combining CNCs masterbatches and PLA resin using twin screw extruder followed by injection molding. Different microscopy techniques were used to investigate the dispersion of CNCs in masterbatches and composites. Thermal, thermomechanical, and mechanical properties of composites were evaluated. Scanning electron microscopy (SEM) images showed superior dispersion of CNCs in spin-coated masterbatches compared to solvent cast masterbatches. At lower CNCs concentrations, both SEM and optical microscope images confirmed more uniform CNCs dispersion in spin-coated composites than solvent cast samples. Degree of crystallinity of PLA exhibited a major enhancement by 147% and 380% in solvent cast and spin-coated composites, respectively. Spin-coated composites with lower CNCs concentration exhibited a noticeable improvement in mechanical properties. However, lower thermal characteristics in spin-coated composites were observed, which could be attributed to the residual solvents in masterbatches. Copyright © 2018 Elsevier Ltd. All rights reserved.

Numerical simulation of the internal stresses of thick tungsten coating deposited by vacuum plasma spraying on copper substrate

International Nuclear Information System (INIS)

Salito, A.; Tului, M.; Casadei, F.

1998-01-01

Several Divertor components in the new generation of nuclear fusion reactors need to be protected against ion sputtering. Particularly copper based (Cu) material is very sensitive to this sputtering process. A solution to overcome such component wear and plasma contamination is to protect the copper substrate with a thick tungsten (W) functional coating. The main difficulty to produce such components is the significant difference in the coating thermomechanical properties between W and Cu. The Vacuum Plasma Spraying coating process (VPS) is a very flexible new economical way to find a solution to the above problem. To optimise the adhesion and stress release properties between the Cu-alloy substrate and the W coating, it is possible to deposit an interlayer as a bond coat between both materials. The aim of this study is to determine the maximum of the residual stresses located between the Cu substrate and the W coating using finite element analysis. The results have been used to select different types of bond coat for the experimental development of thick W coating (>3 mm) on to mock-ups for the Divertor Channel of the ITER project. (author)

Continuously Growing Ultrathick CrN Coating to Achieve High Load-Bearing Capacity and Good Tribological Property.

Science.gov (United States)

Li, Zechao; Wang, Yongxin; Cheng, Xiaoying; Zeng, Zhixiang; Li, Jinlong; Lu, Xia; Wang, Liping; Xue, Qunji

2018-01-24

Continuous growth of traditional monolayer CrN coatings up to 24 h is successfully achieved to fabricate ultrathickness of up to 80 μm on the 316 stainless steel substrate using a multiarc ion plating technique. The microstructures, mechanical properties, and tribological properties evolution with the CrN coating continuously growing was evaluated in detail. The transmission electron microscopy observations and inverse Fourier-filtered images reveal a relaxation mechanism during the continuous growth of CrN coating, which can lead to a decrease in the residual stress when coating growth time exceeds 5 h. The scratch test and friction test results both show that the load-bearing capacity of coating is significantly increased as CrN coatings growing thicker. During the scratch test, the ultrathick CrN coating of thickness 80.6 μm is not failed under the load of 180 N, and the dominant failure mechanism is the cohesive failure including wedge spallation and cracking. The dry-sliding friction test results show the mean coefficient of friction and the wear rate of ultrathick CrN are respectively decreased by 17.2 and 56.8% at most compared with the thin coating (thickness is 5.4 μm). The ultrahigh load-bearing capacity and excellent tribological property are attributed to the relaxation mechanism and limited contact pressure as the coating grows continuously.

A study of the effect of coatings operation on radioiodine removing adsorbents

International Nuclear Information System (INIS)

Freeman, W.P.; Enneking, J.C.

1991-01-01

Nuclear air treatment systems are designed to remove radioactive contaminants from air. If the contaminants are gaseous in form (iodine and its compounds), activated carbon is employed to remove them from the air stream by the process of adsorption. The ability of the carbon to perform its function is checked periodically by sending representative samples to a laboratory for testing. Test methods and conditions are included in the plant technical specification along with failure criteria. When a test sample fails to perform as specified, the carbon in the air cleaning unit must be replaced with new material. Solvents from coating operations can poison carbon by blocking or reducing the surface area available for subsequent reaction of radioiodine compounds. NUCON has developed mathematical models to predict the amount of solvent in the air and residual solvents remaining in the coating at any given time during a coating operation for both normal and accident ventilation modes

Preliminary coating design and coating developments for ATHENA

DEFF Research Database (Denmark)

Jakobsen, Anders Clemen; Ferreira, Desiree Della Monica; Christensen, Finn Erland

2011-01-01

We present initial novel coating design for ATHENA. We make use of both simple bilayer coatings of Ir and B4C and more complex constant period multilayer coatings to enhance the effective area and cover the energy range from 0.1 to 10 keV. We also present the coating technology used...... for these designs and present test results from coatings....

Superconducting magnesium diboride coatings for radio frequency cavities fabricated by hybrid physical-chemical vapor deposition

Science.gov (United States)

Wolak, M. A.; Tan, T.; Krick, A.; Johnson, E.; Hambe, M.; Chen, Ke; Xi, X. X.

2014-01-01

We have investigated the coating of an inner surface of superconducting radio frequency cavities with a magnesium diboride thin film by hybrid physical-chemical vapor deposition (HPCVD). To simulate a 6 GHz rf cavity, a straight stainless steel tube of 1.5-inch inner diameter and a dummy stainless steel cavity were employed, on which small sapphire and metal substrates were mounted at different locations. The MgB2 films on these substrates showed uniformly good superconducting properties including Tc of 37-40 K, residual resistivity ratio of up to 14, and root-mean-square roughness Rq of 20-30 nm. This work demonstrates the feasibility of coating the interior of cylindrical and curved objects with MgB2 by the HPCVD technique, an important step towards superconducting rf cavities with MgB2 coating.

Microscopic observation and statics consideration of tensile fracture of TiC coating on stainless steel

International Nuclear Information System (INIS)

Okawa, Akira; Hasiguti, Ryukiti

1986-01-01

We have measured the tensile fracture properties of the TiC coated SUS316L stainless steel, applying a stress perpendicular to the plane of interface between the coating and the substrate. The fracture of the as grown or non-annealed specimens occurred partially within the TiC layer. A tensile fracture of the TiC coated specimens after vacuum annealing at about 1373 K (1100 deg C) presented arc-shape curved fracture surfaces which can be understood by statics consideration taking into account the maximum stress plane theory and the residual thermal stress. The strengths of non-annealed and annealed specimens are 34.4 MPa (350 kgf/cm 2 ) and 30.2 MPa (308 kgf/cm 2 ), respectively, expressed in terms of Weibull's 50 % fracture stresses. (author)

Thermal cycling behavior of EB-PVD TBCs on CVD platinum modified aluminide coatings

Energy Technology Data Exchange (ETDEWEB)

Xu, Zhenhua, E-mail: zhxubiam@aliyun.com; Wang, Zhankao; Huang, Guanghong; Mu, Rende; He, Limin

2015-07-15

Highlights: • The removed ridges at the grain boundaries with grit blasting. • The ridge, oxidation and cracking are features of damage initiation in TBCs. • Spalled location either at TGO/bond coat interface or inside of TGO layer. • The lower strain energy release rate within TGO layer can prolong of TBCs life. - Abstract: Thermal barrier coating systems (TBCs) including of chemical vapor deposited (Ni, Pt)Al bond coat with grit blasting process and electron beam physical vapor deposited Y{sub 2}O{sub 3}-stabilized-ZrO{sub 2} (YSZ) ceramic coating were investigated. The phase structures, surface and cross-sectional morphologies, cyclic oxidation behaviors and residual stresses of the TBCs were studied in detail. It was found that the fracture path traverses through the ceramic coating to TGO interface, as well as at the TGO to bond coat interface is obviously detected. The change in fracture plane occurs at grain boundaries. The ridge top spallation leads to separate of sufficient size to result in unstable fracture driven by the strain energy stored in the TGO. The bond coat can undergo a volume increase upon oxidation, so that a cavity, enlarged strictly by oxidation would be full to overflowing with TGO layer. The spalled location of the TBCs probably occurs either at the interface of TGO layer and bond coat or inside of TGO layer. The lower strain energy release rate within TGO layer during thermal cycling is beneficial to prolong of TBCs life. The lower is the compressive stress within TGO layer, the longer is the lifetime of TBCs.

Screening of Potential Inhibitor against Coat Protein of Apple Chlorotic Leaf Spot Virus.

Science.gov (United States)

Purohit, Rituraj; Kumar, Sachin; Hallan, Vipin

2018-06-01

In this study, we analyzed Coat protein (CP) of Apple chlorotic leaf spot virus (ACLSV), an important latent virus on Apple. Incidence of the virus is upto 60% in various apple cultivars, affecting yield losses of the order of 10-40% (depending upon the cultivar). CP plays an important role as the sole building block of the viral capsid. Homology approach was used to model 193 amino acid sequence of the coat protein. We used various servers such as ConSurf, TargetS, OSML, COACH, COFACTOR for the prediction of active site residues in coat protein. Virtual screening strategy was employed to search potential inhibitors for CP. Top twenty screened molecules considered for drugability, and toxicity analysis and one potential molecule was further analyzed by docking analysis. Here, we reported a potent molecule which could inhibit the formation of viron assembly by targeting the CP protein of virus.

Electrocurtain coating process for coating solar mirrors

Science.gov (United States)

Kabagambe, Benjamin; Boyd, Donald W.; Buchanan, Michael J.; Kelly, Patrick; Kutilek, Luke A.; McCamy, James W.; McPheron, Douglas A.; Orosz, Gary R.; Limbacher, Raymond D.

2013-10-15

An electrically conductive protective coating or film is provided over the surface of a reflective coating of a solar mirror by flowing or directing a cation containing liquid and an anion containing liquid onto the conductive surface. The cation and the anion containing liquids are spaced from, and preferably out of contact with one another on the surface of the reflective coating as an electric current is moved through the anion containing liquid, the conductive surface between the liquids and the cation containing liquid to coat the conductive surface with the electrically conductive coating.

Study of the diffusion of the radioactivity of glasses and bitumen-coated materials

International Nuclear Information System (INIS)

Rodier, J.; Marichal, M.; Benoit, R.; Niezborala, F.; Le Bouhellec, J.

1969-01-01

Glass pellets obtained from concentrated fission product solutions are subjected to the action of water, in conditions which are as close as possible to those of natural surroundings: still water, renewed water, running water. The retention by a given type of soil of the contamination in waters used for lixiviation is also studied. A comparison is made between various coating processes (bitumen or cement) and vitrification from the point of view of the behaviour in the soil of residues thus treated. The overall results make it possible to choose between the different modes of storage as a function of the activity of the residues to be processed. (authors) [fr

Oxidation protection of multilayer CVD SiC/B/SiC coatings for 3D C/SiC composite

International Nuclear Information System (INIS)

Liu Yongsheng; Cheng Laifei; Zhang Litong; Wu Shoujun; Li Duo; Xu Yongdong

2007-01-01

A CVD boron coating was introduced between two CVD SiC coating layers. EDS and XRD results showed that the CVD B coating was a boron crystal without other impurity elements. SEM results indicated that the CVD B coating was a flake-like or column-like crystal with a compact cross-section. The crack width in the CVD SiC coating deposited on CVD B is smaller than that in a CVD SiC coating deposited on CVD SiC coating. After oxidation at 700 deg. C and 1000 deg. C, XRD results indicated that the coating was covered by product B 2 O 3 or B 2 O 3 .xSiO 2 film. The cracks were sealed as observed by SEM. There was a large amount of flake-like material on hybrid coating surface after oxidation at 1300 deg. C. Oxidation weight loss and residual flexural strength results showed that hybrid SiC/B/SiC multilayer coating provided better oxidation protection for C/SiC composite than a three layer CVD SiC coating at temperatures from 700 deg. C to 1000 deg. C for 600 min, but worse oxidation protection above 1000 deg. C due to the large amount of volatilization of B 2 O 3 or B 2 O 3 .xSiO 2

Numerical Simulation of Temperature Field and Residual Stress Distribution for Laser Cladding Remanufacturing

Directory of Open Access Journals (Sweden)

Liang Hua

2014-05-01

Full Text Available A three-dimensional finite element model was employed to simulate the cladding process of Ni-Cr-B-Si coatings on 16MnR steel under different parameters of laser power, scanning speed, and spot diameter. The temperature and residual stress distribution, the depth of the heat affected zone (HAZ, and the optimized parameters for laser cladding remanufacturing technology were obtained. The orthogonal experiment and intuitive analysis on the depth of the HAZ were performed to study the influence of different cladding parameters. A new criterion based on the ratio of the maximum tensile residual stress and fracture strength of the substrate was proposed for optimization of the remanufacturing parameters. The result showed well agreement with that of the HAZ analysis.

Investigation on the Cathodic Protection Effect of Low Pressure Cold Sprayed AlZn Coating in Seawater via Numerical Simulation

Directory of Open Access Journals (Sweden)

Guosheng Huang

2017-07-01

Full Text Available Cold spray can deposit a composite coating simply by spraying mechanically-mixed Al and Zn powders, while no quantitative data has been reported on the anti-corrosion performance of different composite cold-sprayed coatings. In the present work, the finite element method was used to estimate the cathodic protection effect by simulating the potential distribution on a damaged cold-sprayed AlZn coating on Q235 steel. The results indicate that AlZn coating can only provide a limiting cathodic protection for substrate, because it can only polarize a very narrow zone negative to −0.78 V (vs. SCE, saturated calomel electrode. The remaining area of the steel substrate still has a very high residual corrosion rate. Computational methods can be used to predict the corrosion rate of AlZn coating, and the simulation results were validated by the results of a weight loss experiment.

The 42-kDa coat protein of Andean potato mottle virus acts as a transcriptional activator in yeast

Directory of Open Access Journals (Sweden)

Vidal M.S.

2002-01-01

Full Text Available Interactions of viral proteins play an important role in the virus life cycle, especially in capsid assembly. Andean potato mottle comovirus (APMoV is a plant RNA virus with a virion formed by two coat proteins (CP42 and CP22. Both APMoV coat protein open reading frames were cloned into pGBT9 and pGAD10, two-hybrid system vectors. HF7c yeast cells transformed with the p9CP42 construct grew on yeast dropout selection media lacking tryptophan and histidine. Clones also exhibited ß-galactosidase activity in both qualitative and quantitative assays. These results suggest that CP42 protein contains an amino acid motif able to activate transcription of His3 and lacZ reporter genes in Saccharomyces cerevisiae. Several deletions of the CP42 gene were cloned into the pGBT9 vector to locate the region involved in this activation. CP42 constructions lacking 12 residues from the C-terminal region and another one with 267 residues deleted from the N-terminus are still able to activate transcription of reporter genes. However, transcription activation was not observed with construction p9CP42deltaC57, which does not contain the last 57 amino acid residues. These results demonstrate that a transcription activation domain is present at the C-terminus of CP42 between residues 267 and 374.

Análisis de la respuesta mecánica de recubrimientos elaborados mediante proyección térmica por plasma usando la medición de esfuerzos residuales y el método de elementos finitos a escala estructural: efecto de la red de poros Mechanical responses of plasma sprayed coatings from residual stress measurements and finite element analysis: effect of the pore network architecture

Directory of Open Access Journals (Sweden)

Claudia Constanza Palacio Espinosa

2011-12-01

Full Text Available En el presente trabajo se estudia la respuesta mecánica de recubrimientos elaborados mediante proyección térmica por plasma ante la presencia de esfuerzos residuales y campos de esfuerzos generados por deformaciones. Para lograr este propósito, se midieron los esfuerzos residuales durante el proceso de elaboración de recubrimientos de TiO2-Cu y se evaluó el efecto de la red de poros en la estructura de la capa obtenida a partir de imágenes de alta resolución de Microscopía Electrónica de Barrido (MEB obtenidas de los recubrimientos de Al2O3-13TiO2, las cuales fueron posteriormente procesadas y discretizadas para su análisis mediante el Método de Elementos Finitos (MEF. Algunos parámetros operacionales empleados para elaborar los recubrimientos, tales como el flujo de gases y la corriente eléctrica, necesarios para formar el plasma, mostraron tener influencia en el contenido de poros, densidad de grietas y orientación de las mismas y en la magnitud de los esfuerzos residuales provocados. Los esfuerzos residuales determinados a partir de mediciones de deflexión durante la elaboración de los recubrimientos de TiO2-Cu, permitieron identificar su naturaleza, mientras que las simulaciones numéricas mostraron la gran influencia de la red de poros sobre el campo de esfuerzos de los recubrimientos de Al2O3-13TiO2. Del mismo modo, mediante MEF se evaluaron otras composiciones teóricas a través de la modificación de las propiedades mecánicas intrínsecas de las fases constituyentes. Para los casos considerados, las simulaciones mostraron la pobre influencia que tiene la presencia de los constituyentes secundarios en el campo de esfuerzos de los recubrimientos.This study aims a better understanding residual stress and stress field within composite plasma sprayed coatings submitted to strains. In order to reach out this objective, residual stress techniques can be implemented for measurements during elaboration of coatings and finite

Tribological performance of an H-DLC coating prepared by PECVD

Energy Technology Data Exchange (ETDEWEB)

Solis, J., E-mail: jsolis@ittla.edu.mx [IFS, University of Leeds, School of Mechanical Engineering, Leeds, LS2 9JT (United Kingdom); SEP/SES/TecNM/IT de Tlalnepantla, DEPI-Mechanical Engineering, 54070, Edo. Méx. (Mexico); Zhao, H.; Wang, C. [IFS, University of Leeds, School of Mechanical Engineering, Leeds, LS2 9JT (United Kingdom); Verduzco, J.A. [Instituto de Investigación en Metalurgia y Materiales, UMSNH, P.O. Box 888, 58000, Morelia, Mich. (Mexico); Bueno, A.S. [IFS, University of Leeds, School of Mechanical Engineering, Leeds, LS2 9JT (United Kingdom); Mechanical Engineering Department, Universidade Federal de São João Del Rei, 170 Praça Frei Orlando, 36307-352 São João Del Rei (Brazil); Neville, A. [IFS, University of Leeds, School of Mechanical Engineering, Leeds, LS2 9JT (United Kingdom)

2016-10-15

Highlights: • Duplex hydrogenated Diamond-like Carbon was produced and characterised. • Friction and wear under dry condition of H-DLC/steel tribopair was assessed. • Adhesive strength of the coating was 80N after the scratch tests under dry condition. • Maximum and minimum values of average coefficient of friction were 0.21 and 0.13. • A protective transferred layer on the counterpart produced a carbon-carbon contact. - Abstract: Carbon-based coatings are of wide interest due to their application in machine elements subjected to continuous contact where fluid lubricant films are not permitted. This paper describes the tribological performance under dry conditions of duplex layered H-DLC coating sequentially deposited by microwave excited plasma enhanced chemical vapour deposition on AISI 52100 steel. The architecture of the coating comprised Cr, WC, and DLC (a-C:H) with a total thickness of 2.8 μm and compressive residual stress very close to 1 GPa. Surface hardness was approximately 22 GPa and its reduced elastic modulus around 180 GPa. Scratch tests indicated a well adhered coating achieving a critical load of 80 N. The effect of normal load on the friction and wear behaviours were investigated with steel pins sliding against the actual coating under dry conditions at room temperature (20 ± 2 °C) and 35–50% RH. The results show that coefficient of friction of the coating decreased from 0.21 to 0.13 values with the increase in the applied loads (10–50 N). Specific wear rates of the surface coating also decrease with the increase in the same range of applied loads. Maximum and minimum values were 14 × 10{sup −8} and 5.5 × 10{sup −8} mm{sup −3}/N m, respectively. Through Raman spectroscopy and electron microscopy it was confirmed the carbon-carbon contact, due to the tribolayer formation on the wear scars of the coating and pin. In order to further corroborate the experimental observations regarding the graphitisation behaviour, the

Electroplating chromium on CVD SiC and SiCf-SiC advanced cladding via PyC compatibility coating

Science.gov (United States)

Ang, Caen; Kemery, Craig; Katoh, Yutai

2018-05-01

Electroplating Cr on SiC using a pyrolytic carbon (PyC) bond coat is demonstrated as an innovative concept for coating of advanced fuel cladding. The quantification of coating stress, SEM morphology, XRD phase analysis, and debonding test of the coating on CVD SiC and SiCf-SiC is shown. The residual tensile stress (by ASTM B975) of electroplated Cr is > 1 GPa prior to stress relaxation by microcracking. The stress can remove the PyC/Cr layer from SiC. Surface etching of ∼20 μm and roughening to Ra > 2 μm (by SEM observation) was necessary for successful adhesion. The debonding strength (by ASTM D4541) of the coating on SiC slightly improved from 3.6 ± 1.4 MPa to 5.9 ± 0.8 MPa after surface etching or machining. However, this improvement is limited due to the absence of an interphase, and integrated CVI processing may be required for further advancement.

Tribological investigation of diamond-like carbon coated micro-dimpled surface under bovine serum and osteoarthritis oriented synovial fluid

International Nuclear Information System (INIS)

Ghosh, Subir; Roy, Taposh; Pingguan-Murphy, Belinda; Choudhury, Dipankar; Bin Mamat, Azuddin; Masjuki, H H

2015-01-01

Osteoarthritis-oriented synovial fluid (OASF), i.e., that typical of a patient with osteoarthritis, has different physical and biological characteristics than bovine serum (BS), a lubricant widely used in biotribological investigations. Micro-dimpled and diamond-like carbon- (DLC) coated surfaces are key emerging interfaces for orthopedic implants. In this study, tribological performances of dimpled surfaces, with and without DLC coating, have been investigated under both BS and OASF. The friction tests were performed utilizing a pin on a disk tribometer, whereas contact pressure, speed, and temperature were simulated to a ‘medium walking gait’ of hip joint conditions. The mechanical properties of the specimen and the physical properties of the lubricant were characterized before the friction test. Raman analysis was conducted to identify the coating condition both before and after the test. The DLC-coated dimpled surface showed maximum hardness and residual stress. A DLC-coated dimpled surface under an OASF lubricated condition yielded a lower friction coefficient and wear compared to those of plain and dimpled specimens. The higher graphitization of coated materials with increasing load was confirmed by Raman spectroscopy. (paper)

Tribological investigation of diamond-like carbon coated micro-dimpled surface under bovine serum and osteoarthritis oriented synovial fluid

Science.gov (United States)

Ghosh, Subir; Choudhury, Dipankar; Roy, Taposh; Mamat, Azuddin Bin; Masjuki, H. H.; Pingguan-Murphy, Belinda

2015-06-01

Osteoarthritis-oriented synovial fluid (OASF), i.e., that typical of a patient with osteoarthritis, has different physical and biological characteristics than bovine serum (BS), a lubricant widely used in biotribological investigations. Micro-dimpled and diamond-like carbon- (DLC) coated surfaces are key emerging interfaces for orthopedic implants. In this study, tribological performances of dimpled surfaces, with and without DLC coating, have been investigated under both BS and OASF. The friction tests were performed utilizing a pin on a disk tribometer, whereas contact pressure, speed, and temperature were simulated to a ‘medium walking gait’ of hip joint conditions. The mechanical properties of the specimen and the physical properties of the lubricant were characterized before the friction test. Raman analysis was conducted to identify the coating condition both before and after the test. The DLC-coated dimpled surface showed maximum hardness and residual stress. A DLC-coated dimpled surface under an OASF lubricated condition yielded a lower friction coefficient and wear compared to those of plain and dimpled specimens. The higher graphitization of coated materials with increasing load was confirmed by Raman spectroscopy.

Active coatings technologies for tailorable military coating systems

Science.gov (United States)

Zunino, J. L., III

2007-04-01

The main objective of the U.S. Army's Active Coatings Technologies Program is to develop technologies that can be used in combination to tailor coatings for utilization on Army Materiel. The Active Coatings Technologies Program, ACT, is divided into several thrusts, including the Smart Coatings Materiel Program, Munitions Coatings Technologies, Active Sensor packages, Systems Health Monitoring, Novel Technology Development, as well as other advanced technologies. The goal of the ACT Program is to conduct research leading to the development of multiple coatings systems for use on various military platforms, incorporating unique properties such as self repair, selective removal, corrosion resistance, sensing, ability to modify coatings' physical properties, colorizing, and alerting logistics staff when tanks or weaponry require more extensive repair. A partnership between the U.S. Army Corrosion Office at Picatinny Arsenal, NJ along with researchers at the New Jersey Institute of Technology, NJ, Clemson University, SC, University of New Hampshire, NH, and University of Massachusetts (Lowell), MA, are developing the next generation of Smart Coatings Materiel via novel technologies such as nanotechnology, Micro-electromechanical Systems (MEMS), meta-materials, flexible electronics, electrochromics, electroluminescence, etc. This paper will provide the reader with an overview of the Active Coatings Technologies Program, including an update of the on-going Smart Coatings Materiel Program, its progress thus far, description of the prototype Smart Coatings Systems and research tasks as well as future nanotechnology concepts, and applications for the Department of Defense.

Influence of the residual stresses on crack initiation in brittle materials and structures

International Nuclear Information System (INIS)

Henninger, C.

2007-11-01

Many material assemblies subjected to thermo-mechanical loadings develop thermal residual stresses which modify crack onset conditions. Besides if one of the components has a plastic behaviour, plastic residual deformations may also have a contribution. One of the issues in brittle fracture mechanics is to predict crack onset without any pre-existing defect. Leguillon proposed an onset criterion based on both a Griffth-like energetic condition and a maximum stress criterion. The analysis uses matched asymptotics and the theory of singularity. The good fit between the model and experimental measurements led on homogeneous isotropic materials under pure mechanical loading incited us to take into account residual stresses in the criterion. The comparison between the modified criterion and the experimental measurements carried out on an aluminum/epoxy assembly proves to be satisfying concerning the prediction of failure of the interface between the two components. Besides, it allows, through inversion, identifying the fracture properties of this interface. The modified criterion is also applied to the delamination of the tile/structure interface in the plasma facing components of the Tore Supra tokamak. Indeed thermal and plastic residual stresses appear in the metallic part of these coating tiles. (author)

Systematic Investigation on the Influence of Spray Parameters on the Mechanical Properties of Atmospheric Plasma-Sprayed YSZ Coatings

Science.gov (United States)

Mutter, Markus; Mauer, Georg; Mücke, Robert; Guillon, Olivier; Vaßen, Robert

2018-04-01

In the atmospheric plasma spray (APS) process, micro-sized ceramic powder is injected into a thermal plasma where it is rapidly heated and propelled toward the substrate. The coating formation is characterized by the subsequent impingement of a large number of more or less molten particles forming the so-called splats and eventually the coating. In this study, a systematic investigation on the influence of selected spray parameters on the coating microstructure and the coating properties was conducted. The investigation thereby comprised the coating porosity, the elastic modulus, and the residual stress evolution within the coating. The melting status of the particles at the impingement on the substrate in combination with the substrate surface condition is crucial for the coating formation. Single splats were collected on mirror-polished substrates for selected spray conditions and evaluated by identifying different types of splats (ideal, distorted, weakly bonded, and partially molten) and their relative fractions. In a previous study, these splat types were evaluated in terms of their effect on the above-mentioned coating properties. The particle melting status, which serves as a measure for the particle spreading behavior, was determined by in-flight particle temperature measurements and correlated to the coating properties. It was found that the gun power and the spray distance have a strong effect on the investigated coating properties, whereas the feed rate and the cooling show minor influence.

Flow coating apparatus and method of coating

Science.gov (United States)

Hanumanthu, Ramasubrahmaniam; Neyman, Patrick; MacDonald, Niles; Brophy, Brenor; Kopczynski, Kevin; Nair, Wood

2014-03-11

Disclosed is a flow coating apparatus, comprising a slot that can dispense a coating material in an approximately uniform manner along a distribution blade that increases uniformity by means of surface tension and transfers the uniform flow of coating material onto an inclined substrate such as for example glass, solar panels, windows or part of an electronic display. Also disclosed is a method of flow coating a substrate using the apparatus such that the substrate is positioned correctly relative to the distribution blade, a pre-wetting step is completed where both the blade and substrate are completed wetted with a pre-wet solution prior to dispensing of the coating material onto the distribution blade from the slot and hence onto the substrate. Thereafter the substrate is removed from the distribution blade and allowed to dry, thereby forming a coating.

Significance of White-Coat Hypertension in Older Persons With Isolated Systolic Hypertension

Science.gov (United States)

Franklin, Stanley S.; Thijs, Lutgarde; Hansen, Tine W.; Li, Yan; Boggia, José; Kikuya, Masahiro; Björklund-Bodegård, Kristina; Ohkubo, Takayoshi; Jeppesen, Jørgen; Torp-Pedersen, Christian; Dolan, Eamon; Kuznetsova, Tatiana; Stolarz-Skrzypek, Katarzyna; Tikhonoff, Valérie; Malyutina, Sofia; Casiglia, Edoardo; Nikitin, Yuri; Lind, Lars; Sandoya, Edgardo; Kawecka-Jaszcz, Kalina; Imai, Yutaka; Wang, Jiguang; Ibsen, Hans; O’Brien, Eoin; Staessen, Jan A.

2013-01-01

The significance of white-coat hypertension in older persons with isolated systolic hypertension remains poorly understood. We analyzed subjects from the population-based 11-country International Database on Ambulatory Blood Pressure Monitoring in Relation to Cardiovascular Outcomes database who had daytime ambulatory blood pressure (BP; ABP) and conventional BP (CBP) measurements. After excluding persons with diastolic hypertension by CBP (≥90 mm Hg) or by daytime ABP (≥85 mm Hg), a history of cardiovascular disease, and persons hypertension. During a median follow-up of 10.6 years, there was a total of 655 fatal and nonfatal cardiovascular events. The analyses were stratified by treatment status. In untreated subjects, those with white-coat hypertension (CBP ≥140/hypertension, the cardiovascular risk was similar in elevated conventional and normal daytime systolic BP as compared with those with normal conventional and normal daytime BPs (adjusted hazard rate: 1.10 [95% CI: 0.79–1.53]; P=0.57). However, both treated isolated systolic hypertension subjects with white-coat hypertension (adjusted hazard rate: 2.00; [95% CI: 1.43–2.79]; Phypertension who have their ABP normalized on antihypertensive therapy but with residual white-coat effect by CBP measurement have an entity that we have termed, “treated normalized hypertension.” Therefore, one should be cautious in applying the term “white-coat hypertension” to persons receiving antihypertensive treatment. PMID:22252396

Influence of heat treatment on bond strength and corrosion resistance of sol-gel derived bioglass-ceramic coatings on magnesium alloy.

Science.gov (United States)

Shen, Sibo; Cai, Shu; Xu, Guohua; Zhao, Huan; Niu, Shuxin; Zhang, Ruiyue

2015-05-01

In this study, bioglass-ceramic coatings were prepared on magnesium alloy substrates through sol-gel dip-coating route followed by heat treatment at the temperature range of 350-500°C. Structure evolution, bond strength and corrosion resistance of samples were studied. It was shown that increasing heat treatment temperature resulted in denser coating structure as well as increased interfacial residual stress. A failure mode transition from cohesive to adhesive combined with a maximum on the measured bond strength together suggested that heat treatment enhanced the cohesion strength of coating on the one hand, while deteriorated the adhesion strength of coating/substrate on the other, thus leading to the highest bond strength of 27.0MPa for the sample heat-treated at 450°C. This sample also exhibited the best corrosion resistance. Electrochemical tests revealed that relative dense coating matrix and good interfacial adhesion can effectively retard the penetration of simulated body fluid through the coating, thus providing excellent protection for the underlying magnesium alloy. Copyright © 2015 Elsevier Ltd. All rights reserved.

Role of thermal spray processing method on the microstructure, residual stress and properties of coatings:an integrated study for Ni-5wt.% Al bond coats

Czech Academy of Sciences Publication Activity Database

Sampath, S.; Jiang, X.; Matějíček, Jiří; Prchlík, L.; Kulkarni, A.; Vaidya, A.

2004-01-01

Roč. 364, 1-2 (2004), s. 216-231 ISSN 0921-5093 Grant - others:NSF(US) DMR9632570 Institutional research plan: CEZ:AV0Z2043910 Keywords : bond coats, thermal spraying, microstructure Subject RIV: JG - Metallurgy Impact factor: 1.445, year: 2004

Mini buffy coat photopheresis for children and critically ill patients with extracorporeal photopheresis contraindications.

Science.gov (United States)

Hackstein, Holger; Misterek, Joachim; Nockher, Angelika; Reiter, Alfred; Bein, Gregor; Woessmann, Willi

2009-11-01

Conventional extracorporeal photopheresis (ECP) has proven efficacy for the treatment of several diseases but is limited to patients with sufficient body weight. A novel simplified mini buffy coat ECP technique that allows treatment of small children and patients with apheresis contraindications has been developed. White blood cell (WBC)-rich buffy coat fractions were prepared from 5 to 8 mL/kg whole blood in a closed system, diluted, and ultraviolet A (UVA)-irradiated after addition of 8-methoxypsoralen (8-MOP). Apoptosis and cell death were analyzed by annexin V and 7-aminoactinomycin staining. Lymphocyte proliferation was measured after CD3/CD28 and phytohemagglutinin (PHA) stimulation. Autologous residual blood and UVA-irradiated buffy coat were returned to the patients. Fifty-six mini buffy coat ECP procedures were applied to three children with acute steroid-refractory skin graft-versus-host disease and apheresis contraindications. Mean whole blood and buffy coat volumes were 166 (+/-61.8) and 8 (+/-1.6) mL, respectively, and resulted in a hematocrit of 2.2% (+/-0.4) after saline dilution (median +/- SD). UVA irradiation of 8-MOP buffy coat preparations resulted in significant induction of WBC apoptosis at 48-72 hours (p laboratory side effects were observed during mini ECP procedures and the three patients responded to the therapy. Mini buffy coat ECP induces apoptosis and lymphocyte proliferation inhibition, both of which occur after standard ECP. This study proposes that mini buffy coat ECP be used as a simple and inexpensive alternative to classical ECP in children and adult patients with apheresis contraindications.

Lotus Dust Mitigation Coating and Molecular Adsorber Coating

Science.gov (United States)

O'Connor, Kenneth M.; Abraham, Nithin S.

2015-01-01

NASA Goddard Space Flight Center has developed two unique coating formulations that will keep surfaces clean and sanitary and contain contaminants.The Lotus Dust Mitigation Coating, modeled after the self-cleaning, water-repellant lotus leaf, disallows buildup of dust, dirt, water, and more on surfaces. This coating, has been successfully tested on painted, aluminum, glass, silica, and some composite surfaces, could aid in keeping medical assets clean.The Molecular Adsorber Coating is a zeolite-based, sprayable molecular adsorber coating, designed to prevent outgassing in materials in vacuums. The coating works well to adsorb volatiles and contaminates in manufacturing and processing, such as in pharmaceutical production. The addition of a biocide would also aid in controlling bacteria levels.

Combustion chemical vapor desposited coatings for thermal barrier coating systems

Energy Technology Data Exchange (ETDEWEB)

Hampikian, J.M.; Carter, W.B. [Georgia Institute of Technology, Atlanta, GA (United States)

1995-10-01

The new deposition process, combustion chemical vapor deposition, shows a great deal of promise in the area of thermal barrier coating systems. This technique produces dense, adherent coatings, and does not require a reaction chamber. Coatings can therefore be applied in the open atmosphere. The process is potentially suitable for producing high quality CVD coatings for use as interlayers between the bond coat and thermal barrier coating, and/or as overlayers, on top of thermal barrier coatings.

Studies on the surface modification of TiN coatings using MEVVA ion implantation with selected metallic species

International Nuclear Information System (INIS)

Ward, L.P.; Purushotham, K.P.; Manory, R.R.

2016-01-01

Highlights: • Reduced surface roughness was observed after ion implantation. • W implantation increased residual stress. • Reduced friction and wear accompanied Mo implantation. • Mo implanted layer was more resistant to breakdown during wear testing. • Ion implantation effects can be complex on various implanting species properties. - Abstract: Improvement in the performance of TiN coatings can be achieved using surface modification techniques such as ion implantation. In the present study, physical vapor deposited (PVD) TiN coatings were implanted with Cr, Zr, Nb, Mo and W using the metal evaporation vacuum arc (MEVVA) technique at a constant nominal dose of 4 × 10 16 ions cm −2 for all species. The samples were characterized before and after implantation, using Rutherford backscattering (RBS), glancing incident angle X-ray diffraction (GIXRD), atomic force microscopy (AFM) and optical microscopy. Friction and wear studies were performed under dry sliding conditions using a pin-on-disc CSEM Tribometer at 1 N load and 450 m sliding distance. A reduction in the grain size and surface roughness was observed after implantation with all five species. Little variation was observed in the residual stress values for all implanted TiN coatings, except for W implanted TiN which showed a pronounced increase in compressive residual stress. Mo-implanted samples showed a lower coefficient of friction and higher resistance to breakdown during the initial stages of testing than as-received samples. Significant reduction in wear rate was observed after implanting with Zr and Mo ions compared with unimplanted TiN. The presence of the Ti 2 N phase was observed with Cr implantation.

Quadratic residues and non-residues selected topics

CERN Document Server

Wright, Steve

2016-01-01

This book offers an account of the classical theory of quadratic residues and non-residues with the goal of using that theory as a lens through which to view the development of some of the fundamental methods employed in modern elementary, algebraic, and analytic number theory. The first three chapters present some basic facts and the history of quadratic residues and non-residues and discuss various proofs of the Law of Quadratic Reciprosity in depth, with an emphasis on the six proofs that Gauss published. The remaining seven chapters explore some interesting applications of the Law of Quadratic Reciprocity, prove some results concerning the distribution and arithmetic structure of quadratic residues and non-residues, provide a detailed proof of Dirichlet’s Class-Number Formula, and discuss the question of whether quadratic residues are randomly distributed. The text is a valuable resource for graduate and advanced undergraduate students as well as for mathematicians interested in number theory.

Tablet coating by injection molding technology - Optimization of coating formulation attributes and coating process parameters.

Science.gov (United States)

Desai, Parind M; Puri, Vibha; Brancazio, David; Halkude, Bhakti S; Hartman, Jeremy E; Wahane, Aniket V; Martinez, Alexander R; Jensen, Keith D; Harinath, Eranda; Braatz, Richard D; Chun, Jung-Hoon; Trout, Bernhardt L

2018-01-01

We developed and evaluated a solvent-free injection molding (IM) coating technology that could be suitable for continuous manufacturing via incorporation with IM tableting. Coating formulations (coating polymers and plasticizers) were prepared using hot-melt extrusion and screened via stress-strain analysis employing a universal testing machine. Selected coating formulations were studied for their melt flow characteristics. Tablets were coated using a vertical injection molding unit. Process parameters like softening temperature, injection pressure, and cooling temperature played a very important role in IM coating processing. IM coating employing polyethylene oxide (PEO) based formulations required sufficient room humidity (>30% RH) to avoid immediate cracks, whereas other formulations were insensitive to the room humidity. Tested formulations based on Eudrajit E PO and Kollicoat IR had unsuitable mechanical properties. Three coating formulations based on hydroxypropyl pea starch, PEO 1,000,000 and Opadry had favorable mechanical (35% elongation, >95×10 4 J/m 3 toughness) and melt flow (>0.4g/min) characteristics, that rendered acceptable IM coats. These three formulations increased the dissolution time by 10, 15 and 35min, respectively (75% drug release), compared to the uncoated tablets (15min). Coated tablets stored in several environmental conditions remained stable to cracking for the evaluated 8-week time period. Copyright © 2017 Elsevier B.V. All rights reserved.

New method for determination of epichlorohydrin in epoxy-coated cans by oxolane derivatization and gas chromatography-mass spectrometry.

Science.gov (United States)

Sung, Jun Hyun; Lee, Young Ja; Park, Hyun Jin

2008-08-01

A new method was developed for the determination of epichlorohydrin (ECH) in food contact surface of epoxy-coated cans. The oxolane derivative, which produced by reaction of epoxy moiety in ECH with cyclopentanone in the presence of borontrifluoride-diethyletherate, was analyzed by gas chromatography (GC)/mass spectrometry (MS). 1,2-Epoxyhexane was used as internal standard (IS), which produced an oxolane derivative under the same reaction mechanism as ECH. The developed method was validated with 1 ng ml(-1) of limit of detection (LOD, surface area related 20 ng dm(-2)), >0.999 of linearity. Good precision, which was tested both in terms of intra-day repeatability and inter-day reproducibility, and 97.3-102.7% of good recoveries were obtained on three spiked levels of 5.2, 40.3 and 149.1 ng ml(-1). The excellent validation data suggests that this method is more simple, quick and effective than the official method in European Committee for Standardization (CEN) to determine the residual amount of ECH in food contact materials for food law compliance test. The residual amount of ECH for 13 epoxy-coated can samples was analyzed, and none of the samples was found to be detectable levels of ECH in epoxy-coated cans.

Fatigue of coated and laser hardened steels

International Nuclear Information System (INIS)

La Cruz, P. de.

1990-01-01

In the present work the effect of ion nitriding, laser hardening and hot dip galvanizing upon the fatigue limit and notch sensitivity of a B-Mn Swedish steel SS 2131 have been investigated. The fatigue tests were performed in plane reverse bending fatigue (R=1). The quenched and tempered condition was taken as the reference condition. The microstructure, microhardness, fracture surface and coating appearance of the fatigue surface treated specimens were studied. Residual stress and retained austenite measurements were also carried out. It was found that ion nitriding improves the fatigue limit by 53 % for smooth specimens and by 115 % for notched specimens. Laser hardening improves the fatigue limit by 18 % and 56 % for smooth and notched specimen respectively. Hot dip galvanizing gives a slight deterioration of the fatigue limit (9 % and 10 % for smooth and notched specimen respectively). Ion nitriding and laser hardening decrease the value of the notch sensitivity factor q by 78 % and 65 % respectively. Hot dip galvanizing does not modify it. A simple schematic model based on a residual stress distribution, has been used to explain the different effects. It seems that the presence of the higher compressive residual stresses and the higher uniformity of the microstructure may be the causes of the better fatigue performance of ion nitrided specimens. (119 refs.) (author)

Tensile test of a silicon microstructure fully coated with submicrometer-thick diamond like carbon film using plasma enhanced chemical vapor deposition method

Science.gov (United States)

Zhang, Wenlei; Uesugi, Akio; Hirai, Yoshikazu; Tsuchiya, Toshiyuki; Tabata, Osamu

2017-06-01

This paper reports the tensile properties of single-crystal silicon (SCS) microstructures fully coated with sub-micrometer thick diamond like carbon (DLC) film using plasma enhanced chemical vapor deposition (PECVD). To minimize the deformations or damages caused by non-uniform coating of DLC, which has high compression residual stress, released SCS specimens with the dimensions of 120 µm long, 4 µm wide, and 5 µm thick were coated from the top and bottom side simultaneously. The thickness of DLC coating is around 150 nm and three different bias voltages were used for deposition. The tensile strength improved from 13.4 to 53.5% with the increasing of negative bias voltage. In addition, the deviation in strength also reduced significantly compared to bare SCS sample.

Intense pulsed light annealing of copper zinc tin sulfide nanocrystal coatings

Energy Technology Data Exchange (ETDEWEB)

Williams, Bryce A.; Smeaton, Michelle A.; Holgate, Collin S.; Trejo, Nancy D.; Francis, Lorraine F., E-mail: francis@umn.edu; Aydil, Eray S., E-mail: aydil@umn.edu [Department of Chemical Engineering and Materials Science, University of Minnesota, 151 Amundson Hall, 421 Washington Avenue SE, Minneapolis, Minnesota 55455 (United States)

2016-09-15

A promising method for forming the absorber layer in copper zinc tin sulfide [Cu{sub 2}ZnSnS{sub 4} (CZTS)] thin film solar cells is thermal annealing of coatings cast from dispersions of CZTS nanocrystals. Intense pulsed light (IPL) annealing utilizing xenon flash lamps is a potential high-throughput, low-cost, roll-to-roll manufacturing compatible alternative to thermal annealing in conventional furnaces. The authors studied the effects of flash energy density (3.9–11.6 J/cm{sup 2}) and number of flashes (1–400) during IPL annealing on the microstructure of CZTS nanocrystal coatings cast on molybdenum-coated soda lime glass substrates (Mo-coated SLG). The annealed coatings exhibited cracks with two distinct linear crack densities, 0.01 and 0.2 μm{sup −1}, depending on the flash intensity and total number of flashes. Low density cracking (0.01 μm{sup −1}, ∼1 crack per 100 μm) is caused by decomposition of CZTS at the Mo-coating interface. Vapor decomposition products at the interface cause blisters as they escape the coating. Residual decomposition products within the blisters were imaged using confocal Raman spectroscopy. In support of this hypothesis, replacing the Mo-coated SLG substrate with quartz eliminated blistering and low-density cracking. High density cracking is caused by rapid thermal expansion and contraction of the coating constricted on the substrate as it is heated and cooled during IPL annealing. Finite element modeling showed that CZTS coatings on low thermal diffusivity materials (i.e., SLG) underwent significant differential heating with respect to the substrate with rapid rises and falls of the coating temperature as the flash is turned on and off, possibly causing a build-up of tensile stress within the coating prompting cracking. Use of a high thermal diffusivity substrate, such as a molybdenum foil (Mo foil), reduces this differential heating and eliminates the high-density cracking. IPL annealing in presence of sulfur

Outdoor corrosion of zinc coated carbon steel, determined by thin layer activation

International Nuclear Information System (INIS)

Agostini, M.L.; Laguzzi, G.; De Cristofaro, N.; Stroosnijder, M.F.

2001-01-01

Thin Layer Activation was applied in the frame of a European programme addressed to the evaluation of the corrosion the behaviour of different steels. This included outdoor exposure of zinc coated carbon steel in a rural-marine climatic environment, for a period of several months. The zinc layer of specimens was 10 micrometers thick. For the TLA studies 65Zn radio nuclides were produced along the full depth of the coating, by a cyclotron accelerated deuteron beam. For quantification of the material release, activity versus depth was determined using different thickness of Zn coatings on top the carbon steel. After exposure corrosion product were removed from the surface using a pickling solution and the residual activity was determined by gamma spectrometry. The high sensitivity of the method allowed the evaluation of relatively small thickness losses (i.e. 1.2 micrometer). Thickness loss results, obtained by the TLA method, were compared with those arising from the Atomic Absorption analysis of zinc detected in the pickling solutions. A good agreement was observed between the different methods

Performance of vacuum plasma spray and HVOF bond coatings at 900° and 1100 °C

Energy Technology Data Exchange (ETDEWEB)

Lance, Michael J. [ORNL; Haynes, James A. [ORNL; Pint, Bruce A. [ORNL

2017-12-01

The effects of Ti and B additions to a vacuum plasma sprayed (VPS) NiCoCrAlYHfSi bond coating on thermal barrier coating (TBC) performance were studied at 1100 °C and 900 °C and compared to high-velocity oxy-fuel (HVOF) bond coatings. Using alloy 247 substrates and air plasma sprayed Y2O3-stabilized ZrO2 top coatings, additions of B or Ti + B did not improve the average TBC lifetime in 1-h cycles at 1100 °C in air with 10% H2O. The addition of Ti resulted in a decrease in lifetime. Photo-stimulated luminescence spectroscopy was used to map residual stresses in the thermally-grown Al2O3 scale. At 900 °C, closer to a typical land based turbine operating bond coating temperature, specimens were examined after ten 500-h cycles in laboratory air and air with 10%H2O to study the effect of H2O. The addition of water vapor had little effect on the measured parabolic rate constants at 900 °C and a comparison of the oxide microstructures in both environments is reported.

Application of in-plane x-ray diffraction technique for residual stress measurement of TiN film/WC-Co alloy

International Nuclear Information System (INIS)

Takago, Shigeki; Yasui, Haruyuki; Awazu, Kaoru; Sasaki, Toshihiko; Hirose, Yukio; Sakurai, Kenji

2006-01-01

An in-plane X-ray diffraction technique was used to measure the residual stress of a CVD (chemical vapor deposition) TiN-coated WC-Co alloy. We could obtain the diffraction pattern from a thin film layer, eliminating that of the substrate. In the case of a conventional X-ray diffractometer, the X-ray penetration depth is about few μm. However, for a grazing incidence beam it is only 0.2μm. Depth profiles of residual stress in TiN film layer were evaluated by the present method and the conventional sin 2 ψ technique. We concluded that the in-plane diffraction technique enables us to determine the residual stress in a DVD-TiN film having an oriented texture. It was found that the residual tensile stress generated a mismatch of the coefficient of thermal expansion between the film and the substrate. (author)

Application of in-plane x-ray diffraction technique for residual stress measurement of TiN film/WC-Co alloy

Energy Technology Data Exchange (ETDEWEB)

Takago, Shigeki; Yasui, Haruyuki; Awazu, Kaoru [Industrial Research Inst. of Ishikawa, Kanazawa, Ishikawa (Japan); Sasaki, Toshihiko; Hirose, Yukio [Kanazawa Univ., Dept. of Materials Science and Engineering, Kanazawa, Ishikawa (Japan); Sakurai, Kenji [National Inst. for Materials Science, Tsukuba, Ibaraki (Japan)

2006-06-15

An in-plane X-ray diffraction technique was used to measure the residual stress of a CVD (chemical vapor deposition) TiN-coated WC-Co alloy. We could obtain the diffraction pattern from a thin film layer, eliminating that of the substrate. In the case of a conventional X-ray diffractometer, the X-ray penetration depth is about few {mu}m. However, for a grazing incidence beam it is only 0.2{mu}m. Depth profiles of residual stress in TiN film layer were evaluated by the present method and the conventional sin{sup 2}{psi} technique. We concluded that the in-plane diffraction technique enables us to determine the residual stress in a DVD-TiN film having an oriented texture. It was found that the residual tensile stress generated a mismatch of the coefficient of thermal expansion between the film and the substrate. (author)

Superconducting magnesium diboride coatings for radio frequency cavities fabricated by hybrid physical-chemical vapor deposition

Directory of Open Access Journals (Sweden)

M. A. Wolak

2014-01-01

Full Text Available We have investigated the coating of an inner surface of superconducting radio frequency cavities with a magnesium diboride thin film by hybrid physical-chemical vapor deposition (HPCVD. To simulate a 6 GHz rf cavity, a straight stainless steel tube of 1.5-inch inner diameter and a dummy stainless steel cavity were employed, on which small sapphire and metal substrates were mounted at different locations. The MgB_{2} films on these substrates showed uniformly good superconducting properties including T_{c} of 37–40 K, residual resistivity ratio of up to 14, and root-mean-square roughness R_{q} of 20–30 nm. This work demonstrates the feasibility of coating the interior of cylindrical and curved objects with MgB_{2} by the HPCVD technique, an important step towards superconducting rf cavities with MgB_{2} coating.

Pixelated coatings and advanced IR coatings

Science.gov (United States)

Pradal, Fabien; Portier, Benjamin; Oussalah, Meihdi; Leplan, Hervé

2017-09-01

Reosc developed pixelated infrared coatings on detector. Reosc manufactured thick pixelated multilayer stacks on IR-focal plane arrays for bi-spectral imaging systems, demonstrating high filter performance, low crosstalk, and no deterioration of the device sensitivities. More recently, a 5-pixel filter matrix was designed and fabricated. Recent developments in pixelated coatings, shows that high performance infrared filters can be coated directly on detector for multispectral imaging. Next generation space instrument can benefit from this technology to reduce their weight and consumptions.

RNA2 of grapevine fanleaf virus: sequence analysis and coat protein cistron location.

Science.gov (United States)

Serghini, M A; Fuchs, M; Pinck, M; Reinbolt, J; Walter, B; Pinck, L

1990-07-01

The nucleotide sequence of the genomic RNA2 (3774 nucleotides) of grapevine fanleaf virus strain F13 was determined from overlapping cDNA clones and its genetic organization was deduced. Two rapid and efficient methods were used for cDNA cloning of the 5' region of RNA2. The complete sequence contained only one long open reading frame of 3555 nucleotides (1184 codons, 131K product). The analysis of the N-terminal sequence of purified coat protein (CP) and identification of its C-terminal residue have allowed the CP cistron to be precisely positioned within the polyprotein. The CP produced by proteolytic cleavage at the Arg/Gly site between residues 680 and 681 contains 504 amino acids (Mr 56019) and has hydrophobic properties. The Arg/Gly cleavage site deduced by N-terminal amino acid sequence analysis is the first for a nepovirus coat protein and for plant viruses expressing their genomic RNAs by polyprotein synthesis. Comparison of GFLV RNA2 with M RNA of cowpea mosaic comovirus and with RNA2 of two closely related nepoviruses, tomato black ring virus and Hungarian grapevine chrome mosaic virus, showed strong similarities among the 3' non-coding regions but less similarity among the 5' end non-coding sequences than reported among other nepovirus RNAs.

The coat protein of prunus necrotic ringspot virus specifically binds to and regulates the conformation of its genomic RNA.

Science.gov (United States)

Aparicio, Frederic; Vilar, Marçal; Perez-Payá, Enrique; Pallás, Vicente

2003-08-15

Binding of coat protein (CP) to the 3' nontranslated region (3'-NTR) of viral RNAs is a crucial requirement to establish the infection of Alfamo- and Ilarviruses. In vitro binding properties of the Prunus necrotic ringspot ilarvirus (PNRSV) CP to the 3'-NTR of its genomic RNA using purified E. coli- expressed CP and different synthetic peptides corresponding to a 26-residue sequence near the N-terminus were investigated by electrophoretic mobility shift assays. PNRSV CP bound to, at least, three different sites existing on the 3'-NTR. Moreover, the N-terminal region between amino acid residues 25 to 50 of the protein could function as an independent RNA-binding domain. Single exchange of some arginine residues by alanine eliminated the RNA-interaction capacity of the synthetic peptides, consistent with a crucial role for Arg residues common to many RNA-binding proteins possessing Arg-rich domains. Circular dichroism spectroscopy revealed that the RNA conformation is altered when amino-terminal CP peptides bind to the viral RNA. Finally, mutational analysis of the 3'-NTR suggested the presence of a pseudoknotted structure at this region on the PNRSV RNA that, when stabilized by the presence of Mg(2+), lost its capability to bind the coat protein. The existence of two mutually exclusive conformations for the 3'-NTR of PNRSV strongly suggests a similar regulatory mechanism at the 3'-NTR level in Alfamo- and Ilarvirus genera.

The coat protein of prunus necrotic ringspot virus specifically binds to and regulates the conformation of its genomic RNA

International Nuclear Information System (INIS)

Aparicio, Frederic; Vilar, Marcal; Perez-Paya, Enrique; Pallas, Vicente

2003-01-01

Binding of coat protein (CP) to the 3' nontranslated region (3'-NTR) of viral RNAs is a crucial requirement to establish the infection of Alfamo- and Ilarviruses. In vitro binding properties of the Prunus necrotic ringspot ilarvirus (PNRSV) CP to the 3'-NTR of its genomic RNA using purified E. coli- expressed CP and different synthetic peptides corresponding to a 26-residue sequence near the N-terminus were investigated by electrophoretic mobility shift assays. PNRSV CP bound to, at least, three different sites existing on the 3'-NTR. Moreover, the N-terminal region between amino acid residues 25 to 50 of the protein could function as an independent RNA-binding domain. Single exchange of some arginine residues by alanine eliminated the RNA-interaction capacity of the synthetic peptides, consistent with a crucial role for Arg residues common to many RNA-binding proteins possessing Arg-rich domains. Circular dichroism spectroscopy revealed that the RNA conformation is altered when amino-terminal CP peptides bind to the viral RNA. Finally, mutational analysis of the 3'-NTR suggested the presence of a pseudoknotted structure at this region on the PNRSV RNA that, when stabilized by the presence of Mg 2+ , lost its capability to bind the coat protein. The existence of two mutually exclusive conformations for the 3'-NTR of PNRSV strongly suggests a similar regulatory mechanism at the 3'-NTR level in Alfamo- and Ilarvirus genera

Analysis of Particulate and Chemical Residue Resulting from Exposure to Burning and Abrading Composite Materials

Science.gov (United States)

2013-05-31

National Aeronautics and Space Administration (NASA) initiated a study of reinforcing fiber release from graphite- epoxy composite, graphite- Kevlar ...amplifiers from cut virgin fiber and from fiber produced from burning graphite- epoxy composite were in close agreement.[2] Composite aircraft accidents...containing carbon/ epoxy composite crashed in Denmark in 1991. The recovery team suffered eye and skin irritation and respiratory difficulties.[3

Single layer and multilayer wear resistant coatings of (Ti,Al)N: a review

International Nuclear Information System (INIS)

PalDey, S.; Deevi, S.C.

2003-01-01

We review the status of (Ti,Al)N based coatings obtained by various physical vapor deposition (PVD) techniques and compare their properties. PVD techniques based on sputtering and cathodic arc methods are widely used to deposit wear resistant (Ti,Al)N coatings. These techniques were further modified to improve the metal ionization rate and to eliminate macrodroplets from plasma streams. We summarize manufacture of target/cathode, substrate materials for deposition of coatings, deposition parameters, and the effect of deposition parameters on the physical and mechanical properties of (Ti,Al)N coatings. It is shown that (Ti,Al)N coatings by PVD enhance the wear, thermal, and oxidation resistance of a wide variety of tool materials. We discuss the wear resistant properties of (Ti,Al)N for various machining applications as compared with coatings such as TiN, Ti(C,N) and (Ti,Zr)N. High hardness (∼28-32 GPa), relatively low residual stress (∼5 GPa), superior oxidation resistance, high hot hardness, and low thermal conductivity make (Ti,Al)N coatings most desirable in dry machining and machining of abrasive alloys at high speeds. Multicomponent coatings based on different metallic and nonmetallic elements combine the benefit of individual components leading to a further refinement of coating properties. Alloying additions such as Cr and Y drastically improve the oxidation resistance, Zr and V improve the wear resistance, whereas, Si increases the hardness and resistance to chemical reactivity of the film. Addition of boron improves the abrasive wear behavior of Ti-Al based coatings due to the formation of TiB 2 and BN phases depending on the deposition conditions. Hafnium based nitrides and carbides have potential for resistance to flank and crater wear. The presence of a large number of interfaces between individual layers of a multilayered structure results in a drastic increase in hardness and strength. (Ti,Al)N multilayer super lattice coatings with lattice

Microstructure, Tensile Adhesion Strength and Thermal Shock Resistance of TBCs with Different Flame-Sprayed Bond Coat Materials Onto BMI Polyimide Matrix Composite

Science.gov (United States)

Abedi, H. R.; Salehi, M.; Shafyei, A.

2017-10-01

In this study, thermal barrier coatings (TBCs) composed of different bond coats (Zn, Al, Cu-8Al and Cu-6Sn) with mullite top coats were flame-sprayed and air-plasma-sprayed, respectively, onto bismaleimide matrix composites. These polyimide matrix composites are of interest to replace PMR-15, due to concerns about the toxicity of the MDA monomer from which PMR-15 is made. The results showed that pores and cracks appeared at the bond coat/substrate interface for the Al-bonded TBC because of its high thermal conductivity and diffusivity resulting in transferring of high heat flux and temperature to the polymeric substrate during top coat deposition. The other TBC systems due to the lower conductivity and diffusivity of bonding layers could decrease the adverse thermal effect on the polymer substrate during top coat deposition and exhibited adhesive bond coat/substrate interfaces. The tensile adhesion test showed that the adhesion strength of the coatings to the substrate is inversely proportional to the level of residual stress in the coatings. However, the adhesion strength of Al bond-coated sample decreased strongly after mullite top coat deposition due to thermal damage at the bond coat/substrate interface. TBC system with the Cu-6Sn bond coat exhibited the best thermal shock resistance, while Al-bonded TBC showed the lowest. It was inferred that thermal mismatch stresses and oxidation of the bond coats were the main factors causing failure in the thermal shock test.

Thermal Processing Effects on the Adhesive Strength of PS304 High Temperature Solid Lubricant Coatings

Science.gov (United States)

DellaCorte, Christopher; Edmonds, Brian J.; Benoy, Patricia A.

2001-01-01

In this paper the effects of post deposition heat treatments on the cohesive and adhesive strength properties of PS304, a plasma sprayed nickel-chrome based, high temperature solid lubricant coating deposited on stainless steel, are studied. Plasma spray deposited coating samples were exposed in air at temperatures from 432 to 650 C for up to 500 hr to promote residual stress relief, enhance particle to particle bonding and increase coating to substrate bond strength. Coating pull-off strength was measured using a commercial adhesion tester that utilizes 13 mm diameter aluminum pull studs attached to the coating surface with epoxy. Pull off force was automatically recorded and converted to coating pull off strength. As deposited coating samples were also tested as a baseline. The as-deposited (untreated) samples either delaminated at the coating-substrate interface or failed internally (cohesive failure) at about 17 MPa. Samples heat treated at temperatures above 540 C for 100 hr or at 600 C or above for more than 24 hr exhibited strengths above 31 MPa, nearly a two fold increase. Coating failure occurred inside the body of the coating (cohesive failure) for nearly all of the heat-treated samples and only occasionally at the coating substrate interface (adhesive failure). Metallographic analyses of heat-treated coatings indicate that the Nickel-Chromium binder in the PS304 appears to have segregated into two phases, a high nickel matrix phase and a high chromium precipitated phase. Analysis of the precipitates indicates the presence of silicon, a constituent of a flow enhancing additive in the commercial NiCr powder. The exact nature and structure of the precipitate phase is not known. This microstructural change is believed to be partially responsible for the coating strength increase. Diffusion bonding between particles may also be playing a role. Increasing the heat treatment temperature, exposure time or both accelerate the heat treatment process. Preliminary

Effects of Thermal Exposure on Structures of DD6 Single Crystal Superalloy with Thermal Barrier Coatings

Directory of Open Access Journals (Sweden)

DONG Jianmin

2016-10-01

Full Text Available In order to investigate the effect of water grit-blasting and high temperature thermal exposure on the microstructures of DD6 alloy with TBCs, DD6 single crystal superalloy specimens were water grit-blasted with 0.3 MPa pressure, then the specimens were coated with thermal barrier coatings by electron beam physical vapor deposition (EB-PVD. Specimens with TBCs were exposed at 1100℃ for 50 and 100 hours in the air respectively, and then these specimens were subjected to stress-rupture tests under the condition of 1100℃/130 MPa. The results show that grit-blasting doesn't lead into the recrystallization, thermal exposure can induce element interdiffusion between the bond coat and alloy substrate, the residual stress and element diffusion lead into the changes of γ' phase coarsing direction. After stress rupture tests, the secondary reaction zone emerges into a local area.

Rapid Detection Technology for Pesticides Residues Based on Microelectrodes Impedance Immunosensor

Directory of Open Access Journals (Sweden)

Wen Ping Zhao

2014-09-01

Full Text Available Compared with conventional methods, electrochemical immunosensors have many advantages, such as low cost, high sensitivity, and rapid detection, and has certain prospects for realizing real-time-monitoring. In this paper, a design of portable pesticide residues detection instrument was presented based on an electrochemical impedance immunosensor. Firstly, we studied on an impedance immunosensor based on interdigitated array microelectrode (IDAM coupled with magnetic nanobeads-antibody conjugates (MNAC for the pesticide detection. Magnetic nanobeads (diameter 150 nm coated with anti-carbofuran antibodies were used for further amplification of the binding reaction between antibody and hapten (carbofuran. Secondly, in order to develop a portable pesticide residue apparatus, we designed the impedance detection electric circuit. Main work included designing and constructing of the system circuit, designing and debugging of the system software and so on. Thirdly, the apparatus was used for the standard pesticides solutions testing combined with immunosensor to test the reliability and stability. The pesticide added standard recovery was more than 70 % and the impedance test error was less than 5 %. The results showed that the proposed instrument had a good consistence compared with the traditional analytical methods. Thus, it would be a promising rapid detection instrument for pesticide residues in agricultural products.

The peculiar behavior of the glass transition temperature of amorphous drug-polymer films coated on inert sugar spheres.

Science.gov (United States)

Dereymaker, Aswin; Van Den Mooter, Guy

2015-05-01

Fluid bed coating has been proposed in the past as an alternative technology for manufacturing of drug-polymer amorphous solid dispersions, or so-called glass solutions. It has the advantage of being a one-step process, and thus omitting separate drying steps, addition of excipients, or manipulation of the dosage form. In search of an adequate sample preparation method for modulated differential scanning calorimetry analysis of beads coated with glass solutions, glass transition broadening and decrease of the glass transition temperature (Tg ) were observed with increasing particle size of crushed coated beads and crushed isolated films of indomethacin (INDO) and polyvinylpyrrolidone (PVP). Substituting INDO with naproxen gave comparable results. When ketoconazole was probed or the solvent in INDO-PVP films was switched to dichloromethane (DCM) or a methanol-DCM mixture, two distinct Tg regions were observed. Small particle sizes had a glass transition in the high Tg region, and large particle sizes had a glass transition in the low Tg region. This particle size-dependent glass transition was ascribed to different residual solvent amounts in the bulk and at the surface of the particles. A correlation was observed between the deviation of the Tg from that calculated from the Gordon-Taylor equation and the amount of residual solvent at the Tg of particles with different sizes. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Textures of the soils and rocks at Gusev crater from Spirit's Microscopic Imager

DEFF Research Database (Denmark)

Herkenhoff, K.E.; Squyres, S.W.; Arvidson, R.

2004-01-01

The Microscopic Imager on the Spirit rover analyzed the textures of the soil and rocks at Gusev crater on Mars at a resolution of 100 micrometers. Weakly bound agglomerates of dust are present in the soil near the Columbia Memorial Station. Some of the brushed or abraded rock surfaces show igneous...... textures and evidence for alteration rinds, coatings, and veins consistent with secondary mineralization. The rock textures are consistent with a volcanic origin and subsequent alteration and/or weathering by impact events, wind, and possibly water....

Effect of nano-particulate sol-gel coatings on the oxidation resistance of high-strength steel alloys during the press-hardening process

Energy Technology Data Exchange (ETDEWEB)

Yekehtaz, M.; Benfer, S.; Fuerbeth, W. [DECHEMA-Forschungsinstitut, Theodor-Heuss-Allee 25, D-60486 Frankfurt am Main (Germany); Klesen, C.; Bleck, W. [Institut fuer Eisenhuettenkunde der RWTH Aachen, Intzestrasse 1, D-52072 Aachen (Germany)

2012-10-15

The need for lighter constructional materials in automotive industries has increased the use of high-strength steel alloys. To enhance passenger's safety press hardening may be applied to steel parts. However, as the steel parts are heated up to 950 C during this process they have to be protected by some kind of coating against the intense oxide formation usually taking place. As the coating systems used so far all have certain disadvantages in this work the ability of nano-particulate thin coatings obtained by the sol-gel process to improve the oxidation resistance of 22MnB5 steel is investigated. The coatings obtained from three sols containing lithium aluminum silicate and potassium aluminum silicate showed the best performance against oxidation. The structural properties of the coating materials were characterized using different methods like XRD and differential thermal analysis. Comparison of the oxidation rate constants proved the ability of the coatings to protect against oxidation at temperatures up to 800 C. Press-hardening experiments in combination with investigations on the thermal shock resistance of the coated samples also showed the ability of the coatings to stay intact during press hardening with only slight spalling of the coatings in the bending areas. The absence of any secondary intermetallic phases and layer residues during laser beam welding experiments on coated samples proves the suitability of the nano-particulate coatings for further industrial processing. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Coated Aerogel Beads

Science.gov (United States)

Littman, Howard (Inventor); Plawsky, Joel L. (Inventor); Paccione, John D. (Inventor)

2014-01-01

Methods and apparatus for coating particulate material are provided. The apparatus includes a vessel having a top and a bottom, a vertically extending conduit having an inlet in the vessel and an outlet outside of the vessel, a first fluid inlet in the bottom of the vessel for introducing a transfer fluid, a second fluid inlet in the bottom of the vessel for introducing a coating fluid, and a fluid outlet from the vessel. The method includes steps of agitating a material, contacting the material with a coating material, and drying the coating material to produce a coated material. The invention may be adapted to coat aerogel beads, among other materials. A coated aerogel bead and an aerogel-based insulation material are also disclosed.

MULTI-ZONE ANTIREFLECTION COATING ON A SUBSTRATE MADE OF OPTICAL ZINC SULPHIDE

Directory of Open Access Journals (Sweden)

T. D. Tan

2014-01-01

Full Text Available The paper deals with creation technique for a multi-zone antireflection coating on a substrate made of the optical zinc sulphide ZnS. The coating effectively operates simultaneously in the following spectral ranges: visible region of 450 - 700 nm, in the near infrared region of 1000 - 1100 nm, at the wavelength of 1.55 μm, and in the mid-infrared (IR spectrum of 3 - 5 microns. Reflection coefficient in the range of 450 - 700 nm is not more than 2%, in the range of 1000 - 1100 nm is less than 0.5%, in the range of 1500 - 1700 nm is close to 1.5% and in the range of 3 - 5 μm is equal to 0.6%. Analysis results of the deviation impact in the thickness of layers on the value changing of the energy reflection coefficient in the considered areas are given. Deviation in the thickness of the layer, contiguous with the air, is shown to have the greatest effect on the spectral characteristics of the obtained coating. Refractive index deviation for this layer influences the magnitude of the residual reflection.

Effects of Post Heat Treatments on ZnO Thin-Films Grown on Zn-coated Teflon Substrates

Energy Technology Data Exchange (ETDEWEB)

Kim, Ikhyun; Nam, Giwoong; Lee, Cheoleon; Kim, Dongwhan; Choi, Hyonkwang; Kim, Yangsoo; Leem, Jae-Young [Inje University, Gimhae (Korea, Republic of); Kim, Jin Soo [Chonbuk National University, Jeonju (Korea, Republic of); Kim, Jong Su [Yeungnam University, Gyeongsan (Korea, Republic of); Son, Jeong-Sik [Kyungwoon University, Gumi (Korea, Republic of)

2015-06-15

ZnO thin films were first grown on Zn-coated Teflon substrates using a spin-coating method, with various post-heating temperatures. The structural and optical properties of the ZnO thin films were then investigated using field-effect scanning-electron microscopy, X-ray diffractometry, and photoluminescence (PL) spectroscopy. The surface morphology of these ZnO thin films exhibited dendritic structures. With increasing post-heating temperature, all samples preferentially exhibited preferential c-axis orientation and increased residual tensile stress. All of the films exhibited preferential c-axis orientation, and the residual tensile stress of those increased with increasing post-heating temperature. The near-band-edge emission (NBE) peaks were red-shifted after post-heating treatment at 400 ℃. The intensity of the deep-level emission (DLE) peaks gradually decreased with increasing post- heating temperature. Moreover, the narrowest ‘full width at half maximum’ (FWHM) and the highest intensity ratio of the NBE to the DLE for thin films, were observed after post-heating at 400 ℃. The ZnO thin films fabricated with the 400 ℃ post-heating process provided the highest crystallinity and optical properties.

Effects of organic additives on preferred plane and residual stress of copper electroplated on polyimide

International Nuclear Information System (INIS)

Kim, Jongsoo; Kim, Heesan

2010-01-01

Effects of the preferred plane and the residual stress of an electroplated copper on polyethylene glycol (PEG) and 3-N,N-dimethylaminodithiocarbamoyl-1-propanesulfonic acid (DPS) were studied. Polyimide film coated with sputtered copper was used as a substrate. Preferred plane, residual stress, and impurity level in the electroplated copper were measured by an X-ray diffractometry (XRD), calculated by Stoney's equation, and analyzed with secondary ion mass spectroscopy (SMS), respectively. With increasing the concentration of PEG, the preferred plane changed in the order (1 0 0) and (1 1 0) while with increasing the concentration of DPS, the preferred plane changed in the order (1 1 0), (1 0 0), and (1 1 1). Based on the modified preferred growth model, where the amount of additive adsorbed on a plane is newly assumed to be proportional to its surface energy in vacuum, the predicted preferred planes correspond to the experimental results. The residual stress of the electroplated copper depended on the type of additive as well as its concentration but was independent of the preferred plane. For example, PEG and DPS induced tensile and compressive residual stresses in the electroplated copper, respectively, and their magnitudes increased with their concentrations. The dependency of residual stress on the additives was explained by the incorporated additives into the electroplated copper.

Residual stress and crack initiation in laser clad composite layer with Co-based alloy and WC + NiCr

International Nuclear Information System (INIS)

Lee, Changmin; Park, Hyungkwon; Yoo, Jaehong; Lee, Changhee; Woo, WanChuck; Park, Sunhong

2015-01-01

Highlights: • Major problem, clad cracking in laser cladding process, was researched. • Residual stress measurements were performed quantitatively by neutron diffraction method along the surface of specimens. • Relationship between the residual stress and crack initiation was showed clearly. • Ceramic particle effect in the metal matrix was showed from the results of residual stress measurements. • Initiation sites of generating clad cracks were specifically studied in MMC coatings. - Abstract: Although laser cladding process has been widely used to improve the wear and corrosion resistance, there are unwanted cracking issues during and/or after laser cladding. This study investigates the tendency of Co-based WC + NiCr composite layers to cracking during the laser cladding process. Residual stress distributions of the specimen are measured using neutron diffraction and elucidate the correlation between the residual stress and the cracking in three types of cylindrical specimens; (i) no cladding substrate only, (ii) cladding with 100% stellite#6, and (iii) cladding with 55% stellite#6 and 45% technolase40s. The microstructure of the clad layer was composed of Co-based dendrite and brittle eutectic phases at the dendritic boundaries. And WC particles were distributed on the matrix forming intermediate composition region by partial melting of the surface of particles. The overlaid specimen exhibited tensile residual stress, which was accumulated through the beads due to contraction of the coating layer generated by rapid solidification, while the non-clad specimen showed compressive. Also, the specimen overlaid with 55 wt% stellite#6 and 45 wt% technolase40s showed a tensile stress higher than the specimen overlaid with 100% stellite#6 possibly, due to the difference between thermal expansion coefficients of the matrix and WC particles. Such tensile stresses can be potential driving force to provide an easy crack path ways for large brittle fractures

Residual stress and crack initiation in laser clad composite layer with Co-based alloy and WC + NiCr

Energy Technology Data Exchange (ETDEWEB)

Lee, Changmin; Park, Hyungkwon; Yoo, Jaehong [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Lee, Changhee, E-mail: chlee@hanyang.ac.kr [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Woo, WanChuck [Neutron Science Division, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Park, Sunhong [Research Institute of Industrial Science & Technology, Hyo-ja-dong, Po-Hang, Kyoung-buk, San 32 (Korea, Republic of)

2015-08-01

Highlights: • Major problem, clad cracking in laser cladding process, was researched. • Residual stress measurements were performed quantitatively by neutron diffraction method along the surface of specimens. • Relationship between the residual stress and crack initiation was showed clearly. • Ceramic particle effect in the metal matrix was showed from the results of residual stress measurements. • Initiation sites of generating clad cracks were specifically studied in MMC coatings. - Abstract: Although laser cladding process has been widely used to improve the wear and corrosion resistance, there are unwanted cracking issues during and/or after laser cladding. This study investigates the tendency of Co-based WC + NiCr composite layers to cracking during the laser cladding process. Residual stress distributions of the specimen are measured using neutron diffraction and elucidate the correlation between the residual stress and the cracking in three types of cylindrical specimens; (i) no cladding substrate only, (ii) cladding with 100% stellite#6, and (iii) cladding with 55% stellite#6 and 45% technolase40s. The microstructure of the clad layer was composed of Co-based dendrite and brittle eutectic phases at the dendritic boundaries. And WC particles were distributed on the matrix forming intermediate composition region by partial melting of the surface of particles. The overlaid specimen exhibited tensile residual stress, which was accumulated through the beads due to contraction of the coating layer generated by rapid solidification, while the non-clad specimen showed compressive. Also, the specimen overlaid with 55 wt% stellite#6 and 45 wt% technolase40s showed a tensile stress higher than the specimen overlaid with 100% stellite#6 possibly, due to the difference between thermal expansion coefficients of the matrix and WC particles. Such tensile stresses can be potential driving force to provide an easy crack path ways for large brittle fractures

Characterization, optical properties and laser ablation behavior of epoxy resin coatings reinforced with high reflectivity ceramic particles

Science.gov (United States)

Li, Wenzhi; Kong, Jing; Wu, Taotao; Gao, Lihong; Ma, Zhuang; Liu, Yanbo; Wang, Fuchi; Wei, Chenghua; Wang, Lijun

2018-04-01

Thermal damage induced by high power energy, especially high power laser, significantly affects the lifetime and performance of equipment. High-reflectance coating/film has attracted considerable attention due to its good performance in the damage protection. Preparing a high-reflectance coating with high reaction endothermal enthalpy will effectively consume a large amount of incident energy and in turn protect the substrate from thermal damage. In this study, a low temperature process was used to prepare coatings onto substrate with complex shape and avoid thermal effect during molding. An advanced high reflection ceramic powder, La1‑xSrxTiO3+δ , was added in the epoxy adhesive matrix to improve the reflectivity of coating. The optical properties and laser ablation behaviors of coatings with different ceramic additive ratio of La1‑xSrxTiO3+δ and modified epoxy-La1‑xSrxTiO3+δ with ammonium polyphosphate coatings were investigated, respectively. We found that the reflectivity of coatings is extremely high due to mixed high-reflection La1‑xSrxTiO3+δ particles, up to 96% at 1070 nm, which can significantly improve the laser resistance. In addition, the ammonium polyphosphate modifies the residual carbon structure of epoxy resin from discontinuous fine particles structure to continuous and porous structure, which greatly enhances the thermal-insulation property of coating. Furthermore, the laser ablation threshold is improved obviously, which is from 800 W cm‑2 to 1000 W cm‑2.

Nonadhesive, silica nanoparticles-based brush-coated contact lens cases--compromising between ease of cleaning and microbial transmission to contact lenses.

Science.gov (United States)

Qu, Wenwen; Hooymans, Johanna M M; Qiu, Jun; de-Bont, Nik; Gelling, Onko-Jan; van der Mei, Henny C; Busscher, Henk J

2013-05-01

Surface properties of lens cases are determinant for their cleanability and for microbial transmission from lens cases to contact lenses (CLs). PEG-polymer-brush-coatings are known to decrease microbial adhesion more than other surface-coatings. Here, we applied a robust, silica nanoparticles-based brush-coating to polypropylene cases to evaluate their ease of cleaning and probability of bacterial transmission to CLs. Adhesion forces of nine bacterial strains (Pseudomonas, Staphylococci, and Serratia) to rigid CLs, polypropylene, and silica nanoparticles-based brush-coated polypropylene were measured using atomic-force-microscopy and subjected to Weibull analyses to yield bacterial transmission probabilities. Biofilms of each strain were grown in coated and uncoated cases and rinsed with a NaCl or antimicrobial lens care solution. Residual, viable organisms were quantified. Bacterial adhesion forces of all strains were significantly, up to tenfold smaller on brush-coated than on uncoated polypropylene. This yielded, higher transmission probabilities to a CL, but mild-rinsing yielded 10-100 fold higher removal of bacteria from brush-coated than from polypropylene cases. Moreover, due to weak adhesion forces, bacteria on brush-coated cases were two-to-three fold more susceptible to an antimicrobial lens care solution than on polypropylene cases. Therewith, the design of lens case surfaces is a compromise between ease of cleaning and transmission probability to CLs. Copyright © 2013 Wiley Periodicals, Inc.

Effect of coating parameters on the microstructure of cerium oxide conversion coatings

Energy Technology Data Exchange (ETDEWEB)

Johnson, Benedict Y.; Edington, Joe; O' Keefe, Matthew J

2003-11-25

The microstructure and morphology of cerium oxide conversion coatings prepared under different deposition conditions were characterized by transmission electron microscopy (TEM). The coatings were formed by a spontaneous reaction between a water-based solution containing CeCl{sub 3} and aluminum alloy 7075-T6 substrates. Microstructural characterization was performed to determine the crystallinity of the coatings and to obtain a better understanding of the deposition parameters on coating microstructure. The results of TEM imaging and electron diffraction analysis indicated that the as-deposited coating was composed of nanocrystalline particles of a previously unreported cerium compound. The particles of the coatings produced using glycerol as an additive were found to be much finer than those of the coatings prepared in the absence of glycerol. This indicates that glycerol may act as a grain refiner and/or growth inhibitor during coating deposition. After deposition, the coated panels were treated for 5 min in a phosphate sealing solution. The sealing treatment converted the as-deposited coating into hydrated cerium phosphate. Panels coated from solutions containing no glycerol followed by phosphate sealing performed poorly in salt fog tests. With glycerol addition, the corrosion resistance of the coatings that were phosphate sealed improved considerably, achieving an average passing rate of 85%.

Rheological properties of strawberry fruit coating with methylcellulose

Directory of Open Access Journals (Sweden)

Z Nadim

2016-04-01

Full Text Available Introduction: The maintenance of the quality of fresh products is still a major challenge for the consumers. The most important quality attributes contributing to the marketability of fresh fruit include appearance, color, texture, flavor, nutritional value and microbial safety. Strawberry fruits should be firm but not crunchy. Decreased quality during postharvest handling is most often associated with water loss and decay. The postharvest life of strawberries can be extended by coating technique combined with refrigeration. Application of edible coatings is a conventional method to increase shelf life and maintain fruit quality. Edible coatings can provide an alternative to enlarge fresh fruits’ postharvest life. In this study, the effects of application of methyl cellulose edible coatings and storage time on some mechanical properties, including: the yield stress, yield strain, energy of rupture and modulus of elasticity and also, the viscoelastic behavior of the strawberry fruit was investigated. Materials and Methods: MC (Methocel, Dow Chemical Company, Midland, MI coating was prepared by solubilizing MC powder (3.0 g per 100 mL in a water–ethyl alcohol mixture (2:1 at 75ºC under the high speedmixer (900 rpm for 15 min. Coatings were used directly on the fruit surface. The physical and mechanical characteristics of fruits were analyzed on 2, 5, 8 and 11 days of storage. The puncture test and relaxation test were done using a texture analyzer (Zwick/Roell Model BT1_FR0.5TH.D14, Zwick GmbH Co., Ulm, Germany; using Xforce HP model of loadcell with capacity of 500 N, by 2 mv/v characteristic. General Maxwell model is widely used to analyze experimental results of the stress tests applied for relaxation. The obtained model coefficients were determined and evaluated from relaxation stress curves. Residues were determined using the sequential model. Usually, multicomponent models can properly describe the actual behavior of agricultural

Raman microscopic studies of PVD deposited hard ceramic coatings

International Nuclear Information System (INIS)

Constable, C.P.

2000-01-01

successful. This was then expanded to real wear situations in which tools were monitored after 3,6,12,64,120 and 130 minutes-in-cut. A PCA chemometrics model able to distinguish between component layers and oxides was developed. Raman microscopy was found to provide structural and compositional information on oxide scales formed on the surfaces of heat-treated coatings. Wear debris, generated as a consequence of sliding wear tests on various coatings, was also found to be primarily oxide products. The comparison of the oxide types within the debris to those formed on the surface of the same coating statically oxidised, facilitated a contact temperature during sliding to be estimated. Raman microscopy, owing to the piezo-spectroscopic effect, is sensitive to stress levels. The application of Raman microscopy for the determination of residual compressive stresses within PVD coatings was evaluated. TiAIN/VN superlattice coatings with engineered stresses ranging -3 to -11.3 GPa were deposited onto SS and HSS substrates. Subsequent Raman measurements found a correlation coefficient of 0.996 between Raman band position and stress (determined via XRD methods). In addition, there was also a similar correlation coefficient observed between hardness and Raman shift (cm -1 ). The application of mechanical stresses on a TiAICrN coating via a stress rig was investigated and tensile and compressive shifts were observed. (author)

Analysis of Capillary Coating Die Flow in an Optical Fiber Coating Applicator

OpenAIRE

Kyoungjin Kim

2011-01-01

Viscous heating becomes significant in the high speed resin coating process of glass fibers for optical fiber manufacturing. This study focuses on the coating resin flows inside the capillary coating die of optical fiber coating applicator and they are numerically simulated to examine the effects of viscous heating and subsequent temperature increase in coating resin. Resin flows are driven by fast moving glass fiber and the pressurization at the coating die inlet, while ...

An iodine supplementation of tomato fruits coated with an edible film of the iodide-doped chitosan.

Science.gov (United States)

Limchoowong, Nunticha; Sricharoen, Phitchan; Techawongstien, Suchila; Chanthai, Saksit

2016-06-01

In general, the risk of numerous thyroid cancers inevitably increases among people with iodine deficiencies. An iodide-doped chitosan (CT-I) solution was prepared for dipping tomatoes to coat the fresh surface with an edible film (1.5 μm), thereby providing iodine-rich fruits for daily intake. Characterisation of the thin film was conducted by FTIR and SEM. Stability of the CT-I film was studied via water immersion at various time intervals, and no residual iodide leached out due to intrinsic interactions between the cationic amino group of chitosan and iodide ions. Moreover, the iodide supplement exhibited no effect on the antioxidant activity of tomatoes. The iodine content in the film-coated tomato was determined by ICP-OES. The tomato coating with 1.5% (w/v) CT-I contained approximately 0.4 μg iodide per gram fresh weight. In addition, the freshness and storability of iodine-doped tomatoes were also maintained for shelf-life concerns. Copyright © 2016 Elsevier Ltd. All rights reserved.

Residual stresses

International Nuclear Information System (INIS)

Sahotra, I.M.

2006-01-01

The principal effect of unloading a material strained into the plastic range is to create a permanent set (plastic deformation), which if restricted somehow, gives rise to a system of self-balancing within the same member or reaction balanced by other members of the structure., known as residual stresses. These stresses stay there as locked-in stresses, in the body or a part of it in the absence of any external loading. Residual stresses are induced during hot-rolling and welding differential cooling, cold-forming and extruding: cold straightening and spot heating, fabrication and forced fitting of components constraining the structure to a particular geometry. The areas which cool more quickly develop residual compressive stresses, while the slower cooling areas develop residual tensile stresses, and a self-balancing or reaction balanced system of residual stresses is formed. The phenomenon of residual stresses is the most challenging in its application in surface modification techniques determining endurance mechanism against fracture and fatigue failures. This paper discusses the mechanism of residual stresses, that how the residual stresses are fanned and what their behavior is under the action of external forces. Such as in the case of a circular bar under limit torque, rectangular beam under limt moment, reclaiming of shafts welds and peening etc. (author)

Methods and means for coating paper by film coating

NARCIS (Netherlands)

van der Maarel, Marc; Ter Veer, Arend Berend Cornelis; Vrieling-Smit, Annet; Delnoye, Pierre

2015-01-01

This invention relates to the field of paper coating, more in particular to means and methods for providing paper with at least one layer of pigment using film coating to obtain a well printable surface. Provided is a method for preparing coated paper comprising the steps of: a) providing a

Hygroscopicity and ammonia volatilization losses from nitrogen sources in coated urea

Directory of Open Access Journals (Sweden)

Letícia de Abreu Faria

2014-06-01

Full Text Available Hygroscopic fertilizers tend to absorb moisture from the air and may have undesirable characteristics such as moistness, clumping and lower fluidity, hampering the application. The increasing use of urea is due to its numerous advantages, although this nitrogen (N source is highly susceptible to volatilization losses, particularly when applied to the soil surface of management systems with conservation of crop residues. The volatilization losses can be minimized by slow or controlled-release fertilizers, with controlled water solubility of the urea-coating materials; and by stabilized fertilizers, which prolong the period during which N remains in the amide or ammonia forms by urease inhibitors. This study evaluated the hygroscopicity of and ammonia volatilization from urea coated with boric acid and copper sulfate or with sulfur. The hygroscopicity of the sources was evaluated over time after exposure to five levels of relative humidity (RH and volatilization evaluated after application to the soil surface covered with sugarcane trash. Ammonium nitrate has a low potential for volatilization losses, but is highly hygroscopic. Although coating with boric acid and copper sulfate or elemental sulfur reduced the critical humidity level of urea, the delay in the volatilization process is a potential positive factor.

Superhard behaviour, low residual stress, and unique structure in diamond-like carbon films by simple bilayer approach

International Nuclear Information System (INIS)

Dwivedi, Neeraj; Kumar, Sushil; Malik, Hitendra K.

2012-01-01

Simple bilayer approach is proposed for synthesizing hard and superhard diamond-like carbon (DLC) coatings with reduced residual stress. For this, M/DLC bilayer (M = Ti and Cu) structures are grown using hybrid system involving radio frequency (RF)-sputtering and RF-plasma enhanced chemical vapor deposition techniques. Ti/DLC bilayer deposited at negative self bias of 100 V shows superhard behaviour with hardness (H) as 49 GPa. Cu/DLC bilayer grown at self bias of 100 V exhibits hard behaviour with H as 22.8 GPa. The hardness of Ti/DLC (Cu/DLC) bilayer gets changed from superhard (hard) to hard (moderate hard) regime, when the self bias is raised to 300 V. Residual stress in Ti/DLC (Cu/DLC) bilayer is found to be significantly low that varies in the range of 1 GPa-1.65 GPa (0.8 GPa-1.6 GPa). The microstructure and morphology are studied by Raman spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). SEM and AFM pictures reveal the creation of nanostructured features in the deposited bilayers. Raman, SEM, and AFM analyses are correlated with the nano-mechanical properties. Owing to excellent nano-mechanical properties, these bilayers can find their direct industrial applications as hard and protective coatings.

Influence of the Manufacturing Process on Defects in the Galvanized Coating of High Carbon Steel Wires

Directory of Open Access Journals (Sweden)

Marcello Gelfi

2017-03-01

Full Text Available This study is a detailed failure analysis of galvanized high carbon steel wires, which developed coating cracks during the torsion test performed as a quality control at the end of the manufacturing process. Careful visual inspections showed that the cracks are already present in the coating before the torsion test. In order to explain the origin of these cracks, systematic metallographic investigations were performed by means of optical and scanning electron microscope on both the wires and the rods that have been cold drawn to produce the wire. The chemical composition of the galvanized coatings was evaluated by means of energy dispersive spectroscopy. Micro bidimensional X-ray diffraction experiments were also performed to measure the residual stresses in the galvanized coating. The results showed that the failure is related to two main factors: the relatively high content of silicon in the steel and the unsuitable cooling rate of the rods at the exit from the galvanizing bath. The mechanism proposed to explain the origin of the defects was supported by Finite Elements Methods simulations and verified with in-plant tests. The proper countermeasures were then applied and the problem successfully solved.

Influence of the Manufacturing Process on Defects in the Galvanized Coating of High Carbon Steel Wires.

Science.gov (United States)

Gelfi, Marcello; Solazzi, Luigi; Poli, Sandro

2017-03-06

This study is a detailed failure analysis of galvanized high carbon steel wires, which developed coating cracks during the torsion test performed as a quality control at the end of the manufacturing process. Careful visual inspections showed that the cracks are already present in the coating before the torsion test. In order to explain the origin of these cracks, systematic metallographic investigations were performed by means of optical and scanning electron microscope on both the wires and the rods that have been cold drawn to produce the wire. The chemical composition of the galvanized coatings was evaluated by means of energy dispersive spectroscopy. Micro bidimensional X-ray diffraction experiments were also performed to measure the residual stresses in the galvanized coating. The results showed that the failure is related to two main factors: the relatively high content of silicon in the steel and the unsuitable cooling rate of the rods at the exit from the galvanizing bath. The mechanism proposed to explain the origin of the defects was supported by Finite Elements Methods simulations and verified with in-plant tests. The proper countermeasures were then applied and the problem successfully solved.

H2 Equilibrium Pressure with a Neg-Coated Vacuum Chamber as a Function of Temperature and H2 Concentration

CERN Document Server

Rossi, Adriana

2006-01-01

Non Evaporable Getter (NEG) coating is used in the Large Hadron Collider (LHC) room-temperature sections to ensure a low residual gas pressure for its properties of distributed pumping, low outgassing and desorption under particle bombardment; and to limit or cure electron cloud build-up due to its low secondary electron emission. In certain regions of the LHC, and in particular close to the beam collimators, the temperature of the vacuum chamber is expected to rise due to energy deposition from particle losses. Hydrogen molecules are pumped by the NEG via dissociation on the surface, sorption at the superficial sites and diffusion into the NEG bulk. In the case of hydrogen, the sorption is thermally reversible, causing the dissociation pressure to increase with NEG temperature and amount of H2 pumped. Measurements were carried out on a stainless steel chamber coated with TiZrV NEG as a function of the H2 concentration and the chamber temperature, to estimate the residual gas pressure in the collimator region...

In situ Measurements of Residual Stresses and Elelastic Moduli in Thermal Sprayed Coatings. Part 1: Apparatus and Analysis

Czech Academy of Sciences Publication Activity Database

Matějíček, Jiří; Sampath, S.

2003-01-01

Roč. 51, č. 3 (2003), s. 863-872 ISSN 1359-6454 Grant - others:NSF(US) DMR9632570 Institutional research plan: CEZ:AV0Z2043910 Keywords : coatings plasma spraying, mechanical properties testing, elastic modulus Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 3.059, year: 2003

Stent Coating Integrity of Durable and Biodegradable Coated Drug Eluting Stents.

Science.gov (United States)

Yazdani, Saami K; Sheehy, Alexander; Pacetti, Stephen; Rittlemeyer, Brandon; Kolodgie, Frank D; Virmani, Renu

2016-10-01

Coatings consisting of a polymer and drug are widely used in drug-eluting stents (DES) and are essential in providing programmable drug release kinetics. Among other factors, stent coating technologies can influence blood compatibility, affect acute and sub-acute healing, and potentially trigger a chronic inflammatory response. The aim of this study was to investigate the short-term (7 and 28 days) and long-term (90 and 180 days) coating integrity of the Xience Prime Everolimus-Eluting Stent (EES), Resolute Zotarolimus-Eluting Stent (ZES), Taxus Paclitaxel-Eluting Stent (PES), and Nobori Biolimus A9-Eluting Stent (BES) in a rabbit ilio-femoral stent model. Stented arteries (n = 48) were harvested and the tissue surrounding the implanted stents digested away with an enzymatic solution. Results demonstrated that the majority of struts of EES were without any coating defects with a few struts showing minor defects. Similarly, for the ZES, most of the struts were without coating defects at all time points except at 180 days. The majority of PES demonstrated mostly webbing and uneven coating. In the BES group, the majority of strut coating showed polymer cracking. Overall, the EES and ZES had fewer coating defects than the PES and BES. Coating defects, however increase over time for the ZES, whereas the percent of coating irregularities remained constant for the EES. These results provide, for the first time, a comparison of the long-term durability of these drug-eluting stent coatings in vivo. © 2016, Wiley Periodicals, Inc.

Development and electrochemical characterization of Ni‐P coated tungsten incorporated electroless nickel coatings

Energy Technology Data Exchange (ETDEWEB)

Shibli, S.M.A., E-mail: smashibli@yahoo.com; Chinchu, K.S.

2016-08-01

Ni‐P-W alloy and composite coatings were prepared by incorporation of sodium tungstate/tungsten and Ni‐P coated tungsten into electroless nickel bath respectively. Good inter-particle interactions among the depositing elements i.e. Ni and P with the incorporating tungsten particles were achieved by means of pre-coated tungsten particle by electroless nickel covering prior to its addition into the electroless bath. The pre-coated tungsten particles got incorporated uniformly into the Ni-P matrix of the coating. The particles and the coatings were characterized at different stages by different techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The electroless Ni-P coating incorporated with pre-coated tungsten exhibited considerably high hardness, thickness and deposition rate. The performance and corrosion resistance characteristics of the composite coating incorporated with the nickel coated tungsten were found to be superior over other conventional Ni-P-W ternary alloy coatings currently reported. - Highlights: • An amorphous Ni-P coating was effectively formed on tungsten particles. • Electroless ternary Ni-P-W composite coatings were successfully prepared. • Enhancement in the inter-particle interaction in the Ni-P composite matrix was achieved. • Efficient and uniform incorporation of the composite in the internal layer was evident. • The tungsten incorporated coating possessed effective barrier protection.

Residual stresses

International Nuclear Information System (INIS)

Macherauch, E.

1978-01-01

Residual stresses are stresses which exist in a material without the influence of external powers and moments. They come into existence when the volume of a material constantly changes its form as a consequence of mechanical, thermal, and/or chemical processes and is hindered by neighbouring volumes. Bodies with residual stress are in mechanical balance. These residual stresses can be manifested by means of all mechanical interventions disturbing this balance. Acoustical, optical, radiological, and magnetical methods involving material changes caused by residual stress can also serve for determining residual stress. Residual stresses have an ambivalent character. In technical practice, they are feared and liked at the same time. They cause trouble because they can be the cause for unexpected behaviour of construction elements. They are feared since they can cause failure, in the worst case with catastrophical consequences. They are appreciated, on the other hand, because, in many cases, they can contribute to improvements of the material behaviour under certain circumstances. But they are especially liked for their giving convenient and (this is most important) mostly uncontrollable explanations. For only in very few cases we have enough knowledge and possibilities for the objective evaluation of residual stresses. (orig.) [de

Laser-induced reaction alumina coating on ceramic composite

Science.gov (United States)

Xiao, Chenghe

Silicon carbide ceramics are susceptible to corrosion by certain industrial furnace environments. It is also true for a new class of silicon carbide-particulate reinforced alumina-matrix composite (SiCsb(P)Alsb2Osb3) since it contains more than 55% of SiC particulate within the composite. This behavior would limit the use of SiCsb(P)Alsb2Osb3 composites in ceramic heat exchangers. Because oxide ceramics corrode substantially less in the same environments, a laser-induced reaction alumina coating technique has been developed for improving corrosion resistance of the SiCsb(P)Alsb2Osb3 composite. Specimens with and without the laser-induced reaction alumina coating were subjected to corrosion testing at 1200sp°C in an air atmosphere containing Nasb2COsb3 for 50 ˜ 200 hours. Corroded specimens were characterized via x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS). The uncoated SiCsbP/Alsb2Osb3 composite samples experienced an initial increase in weight during the exposure to Nasb2COsb3 at 1200sp°C due to the oxidation of residual aluminum metal in the composite. There was no significant weight change difference experienced during exposure times between 50 and 200 hours. The oxidation layer formed on the as-received composite surface consisted of Si and Alsb2Osb3 (after washing with a HF solution). The oxidation layer grew outward and inward from the original surface of the composite. The growth rate in the outward direction was faster than in the inward direction. The formation of the Si/Alsb2Osb3 oxidation layer on the as-received composite was nonuniform, and localized corrosion was observed. The coated samples experienced very little mass increase. The laser-induced reaction alumina coating effectively provided protection for the SiCsbP/Alsb2Osb3 composite by keeping the corrodents from contacting the composite and by the formation of some refractory compounds such as Nasb2OAlsb2Osb3SiOsb2 and Nasb2Alsb{22}Osb

Investigation of hydrophobic substrates for solution residue analysis utilizing an ambient desorption liquid sampling-atmospheric pressure glow discharge microplasma.

Science.gov (United States)

Paing, Htoo W; Marcus, R Kenneth

2018-03-12

A practical method for preparation of solution residue samples for analysis utilizing the ambient desorption liquid sampling-atmospheric pressure glow discharge optical emission spectroscopy (AD-LS-APGD-OES) microplasma is described. Initial efforts involving placement of solution aliquots in wells drilled into copper substrates, proved unsuccessful. A design-of-experiment (DOE) approach was carried out to determine influential factors during sample deposition including solution volume, solute concentration, number of droplets deposited, and the solution matrix. These various aspects are manifested in the mass of analyte deposited as well as the size/shape of the product residue. Statistical analysis demonstrated that only those initial attributes were significant factors towards the emission response of the analyte. Various approaches were investigated to better control the location/uniformity of the deposited sample. Three alternative substrates, a glass slide, a poly(tetrafluoro)ethylene (PTFE) sheet, and a polydimethylsiloxane (PDMS)-coated glass slide, were evaluated towards the microplasma analytical performance. Co-deposition with simple organic dyes provided an accurate means of determining the location of the analyte with only minor influence on emission responses. The PDMS-coated glass provided the best performance by virtue of its providing a uniform spatial distribution of the residue material. This uniformity yielded an improved limits of detection by approximately 22× for 20 μL and 4 x for 2 μL over the other two substrates. While they operate by fundamentally different processes, this choice of substrate is not restricted to the LS-APGD, but may also be applicable to other AD methods such as DESI, DART, or LIBS. Further developments will be directed towards a field-deployable ambient desorption OES source for quantitative analysis of microvolume solution residues of nuclear forensics importance.

DLC-Si protective coatings for polycarbonates

Directory of Open Access Journals (Sweden)

Damasceno J.C.

2003-01-01

Full Text Available In this work, a-C:H:Si (DLC-Si films were produced onto crystalline silicon and polycarbonate substrates by the rf-PACVD technique from gaseous mixtures of CH4 + SiH4 and C2H2 + SiH4. The effects of self-bias and gas composition upon mechanical and optical properties of the films were investigated. Micro-hardness, residual stress, surface roughness and refractive index measurements were employed for characterization. By incorporating low concentrations of silicon and by exploring the more favorable conditions for the rf-PACVD deposition technique, highly adherent DLC-Si thin films were produced with reduced internal stresses (lower than 1 GPa, high hardness (around 20 GPa and high deposition rates (up to 10 µm/h. Results that show the technological viability of this material for application as protective coatings for polycarbonates are also discussed.

Evaluation of residue-residue contact predictions in CASP9

KAUST Repository

Monastyrskyy, Bohdan

2011-01-01

This work presents the results of the assessment of the intramolecular residue-residue contact predictions submitted to CASP9. The methodology for the assessment does not differ from that used in previous CASPs, with two basic evaluation measures being the precision in recognizing contacts and the difference between the distribution of distances in the subset of predicted contact pairs versus all pairs of residues in the structure. The emphasis is placed on the prediction of long-range contacts (i.e., contacts between residues separated by at least 24 residues along sequence) in target proteins that cannot be easily modeled by homology. Although there is considerable activity in the field, the current analysis reports no discernable progress since CASP8.

Interface control of atomic layer deposited oxide coatings by filtered cathodic arc deposited sublayers for improved corrosion protection

Energy Technology Data Exchange (ETDEWEB)

Härkönen, Emma, E-mail: emma.harkonen@helsinki.fi [Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki (Finland); Tervakangas, Sanna; Kolehmainen, Jukka [DIARC-Technology Inc., Espoo (Finland); Díaz, Belén; Światowska, Jolanta; Maurice, Vincent; Seyeux, Antoine; Marcus, Philippe [Laboratoire de Physico-Chimie des Surfaces, CNRS (UMR 7075) – Chimie ParisTech (ENSCP), F-75005 Paris (France); Fenker, Martin [FEM Research Institute, Precious Metals and Metals Chemistry, D-73525 Schwäbisch Gmünd (Germany); Tóth, Lajos; Radnóczi, György [Research Centre for Natural Sciences HAS, (MTA TKK), Budapest (Hungary); Ritala, Mikko [Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki (Finland)

2014-10-15

Sublayers grown with filtered cathodic arc deposition (FCAD) were added under atomic layer deposited (ALD) oxide coatings for interface control and improved corrosion protection of low alloy steel. The FCAD sublayer was either Ta:O or Cr:O–Ta:O nanolaminate, and the ALD layer was Al{sub 2}O{sub 3}–Ta{sub 2}O{sub 5} nanolaminate, Al{sub x}Ta{sub y}O{sub z} mixture or graded mixture. The total thicknesses of the FCAD/ALD duplex coatings were between 65 and 120 nm. Thorough analysis of the coatings was conducted to gain insight into the influence of the FCAD sublayer on the overall coating performance. Similar characteristics as with single FCAD and ALD coatings on steel were found in the morphology and composition of the duplex coatings. However, the FCAD process allowed better control of the interface with the steel by reducing the native oxide and preventing its regrowth during the initial stages of the ALD process. Residual hydrocarbon impurities were buried in the interface between the FCAD layer and steel. This enabled growth of ALD layers with improved electrochemical sealing properties, inhibiting the development of localized corrosion by pitting during immersion in acidic NaCl and enhancing durability in neutral salt spray testing. - Highlights: • Corrosion protection properties of ALD coatings were improved by FCAD sublayers. • The FCAD sublayer enabled control of the coating-substrate interface. • The duplex coatings offered improved sealing properties and durability in NSS. • The protective properties were maintained during immersion in a corrosive solution. • The improvements were due to a more ideal ALD growth on the homogeneous FCAD oxide.

Contextual Role of a Salt Bridge in the Phage P22 Coat Protein I-Domain*

Science.gov (United States)

Harprecht, Christina; Okifo, Oghenefejiro; Robbins, Kevin J.; Motwani, Tina; Alexandrescu, Andrei T.; Teschke, Carolyn M.

2016-01-01

The I-domain is a genetic insertion in the phage P22 coat protein that chaperones its folding and stability. Of 11 acidic residues in the I-domain, seven participate in stabilizing electrostatic interactions with basic residues across elements of secondary structure, fastening the β-barrel fold. A hydrogen-bonded salt bridge between Asp-302 and His-305 is particularly interesting as Asp-302 is the site of a temperature-sensitive-folding mutation. The pKa of His-305 is raised to 9.0, indicating the salt bridge stabilizes the I-domain by ∼4 kcal/mol. Consistently, urea denaturation experiments indicate the stability of the WT I-domain decreases by 4 kcal/mol between neutral and basic pH. The mutants D302A and H305A remove the pH dependence of stability. The D302A substitution destabilizes the I-domain by 4 kcal/mol, whereas H305A had smaller effects, on the order of 1–2 kcal/mol. The destabilizing effects of D302A are perpetuated in the full-length coat protein as shown by a higher sensitivity to protease digestion, decreased procapsid assembly rates, and impaired phage production in vivo. By contrast, the mutants have only minor effects on capsid expansion or stability in vitro. The effects of the Asp-302–His-305 salt bridge are thus complex and context-dependent. Substitutions that abolish the salt bridge destabilize coat protein monomers and impair capsid self-assembly, but once capsids are formed the effects of the substitutions are overcome by new quaternary interactions between subunits. PMID:27006399

Effect of Kaolin Clay and Alumina on Thermal Performance and Char Morphology of Intumescent fire retardant coating

Directory of Open Access Journals (Sweden)

aziz Hammad

2014-07-01

Full Text Available Intumescent fire retardant coating (IFRC have been developed by using ammonium polyphosphate, expandable graphite, melamine, boric acid, kaolin clay and alumina as fillers bound together with epoxy resin and cured with the help of curing agent. Five different formulations were developed with and without using fillers. Cured samples were burned in furnace at 500°C for 2h for char expansion. Bunsen burner test was performed for 1h using UL-94 vertical burning test to investigate the thermal performance of IFRC. The resultant char obtained after burning of coated samples were characterized by using field emission scanning electron microscopy for char morphology. Char composition was analyzed by using fourier transform infrared spectroscopy. Thermogravimetric analysis was carried out to investigate the residual weight of coating. Results showed that formulation with 0.5 weight % of kaolin clay and 0.5 weight % of alumina provide best thermal performance, uniform and multi-porous char structure with high anti-oxidation property.

Residual Stress Distribution and Microstructure of a Multiple Laser-Peened Near-Alpha Titanium Alloy

Science.gov (United States)

Umapathi, A.; Swaroop, S.

2018-04-01

Laser peening without coating (LPwC) was performed on a Ti-2.5 Cu alloy with multiple passes (1, 3 and 5), using a Nd:YAG laser (1064 nm) at a constant overlap rate of 70% and power density of 6.7 GW cm-2. Hardness and residual stress profiles indicated thermal softening near the surface (hardness (235 HV at 500 μm) and maximum residual stress (- 890 MPa at 100 μm) were observed for LPwC with 1 pass. Surface roughness and surface 3-D topography imaging showed that the surface roughness increased with the increase in the number of passes. XRD results indicated no significant β phases. However, peak shifts, broadening and asymmetry were observed and interpreted based on dislocation activity. Microstructures indicated no melting or resolidification or refinement of grains at the surface. Twin density was found to increase with the increase in the number of passes.

Study of the surface resistance of niobium sputter-coated copper cavities

CERN Document Server

Benvenuti, Cristoforo; Campisi, I E; Darriulat, Pierre; Peck, M A; Russo, R; Valente, A M

1999-01-01

A systematic study of the superconducting properties of niobium films deposited on the inner wall of copper radiofrequency cavities is presented. Films are grown by sputtering with different discharge gases (Xe, Kr, Ar and Ar/Ne mixtures) on substrates prepared under different conditions. The measured quantities include the surface resistance at 1.5 GHz, the critical temperature and the penetration depth. The surface resistance is analyzed in terms of its dependence on temperature, RF field and the density of trapped fluxons. Once allowance for electron scattering is made by means of a single mean free path parameter, good agreement with BCS theory is observed. The residual resistance is observed to be essentially noncorrelated with the superconducting properties, although influenced by specific coating conditions. On occasions, very low residual resistances, in the nano-ohm range, have been maintained over a broad range of RF field, indicating the absence of fundamental limitations specific to the film techn...

Nanosecond multi-pulse laser milling for certain area removal of metal coating on plastics surface

Science.gov (United States)

Zhao, Kai; Jia, Zhenyuan; Ma, Jianwei; Liu, Wei; Wang, Ling

2014-12-01

Metal coating with functional pattern on engineering plastics surface plays an important role in industry applications; it can be obtained by adding or removing certain area of metal coating on engineering plastics surface. However, the manufacturing requirements are improved continuously and the plastic substrate presents three-dimensional (3D) structure-many of these parts cannot be fabricated by conventional processing methods, and a new manufacturing method is urgently needed. As the laser-processing technology has many advantages like high machining accuracy and constraints free substrate structure, the machining of the parts is studied through removing certain area of metal coating based on the nanosecond multi-pulse laser milling. To improve the edge quality of the functional pattern, generation mechanism and corresponding avoidance strategy of the processing defects are studied. Additionally, a prediction model for the laser ablation depth is proposed, which can effectively avoid the existence of residual metal coating and reduces the damage of substrate. With the optimal machining parameters, an equiangular spiral pattern on copper-clad polyimide (CCPI) is machined based on the laser milling at last. The experimental results indicate that the edge of the pattern is smooth and consistent, the substrate is flat and without damage. The achievements in this study could be applied in industrial production.

Investigation on the Interface Characteristics of the Thermal Barrier Coating System through Flat Cylindrical Indenters

Directory of Open Access Journals (Sweden)

Shifeng Wen

2014-01-01

Full Text Available Thermal barrier coating (TBC systems are highly advanced material systems and usually applied to insulate components from large and prolonged heat loads by utilizing thermally insulating materials. In this study, the characteristics of the interface of thermal barrier coating systems have been simulated by the finite-element method (FEM. The emphasis was put on the stress distribution at the interface which is beneath the indenter. The effect of the interface roughness, the thermally grown oxide (TGO layer's thickness, and the modulus ratio (η of the thin film with the substrate has been considered. Finite-element results showed that the influences of the interface roughness and the TGO layer's thickness on stress distribution were important. At the same time, the residual stress distribution has been investigated in detail.

Mixed zirconia calcium phosphate coatings for dental implants: Tailoring coating stability and bioactivity potential

International Nuclear Information System (INIS)

Pardun, Karoline; Treccani, Laura; Volkmann, Eike; Streckbein, Philipp; Heiss, Christian; Destri, Giovanni Li; Marletta, Giovanni; Rezwan, Kurosch

2015-01-01

Enhanced coating stability and adhesion are essential for long-term success of orthopedic and dental implants. In this study, the effect of coating composition on mechanical, physico-chemical and biological properties of coated zirconia specimens is investigated. Zirconia discs and dental screw implants are coated using the wet powder spraying (WPS) technique. The coatings are obtained by mixing yttria-stabilized zirconia (TZ) and hydroxyapatite (HA) in various ratios while a pure HA coating served as reference material. Scanning electron microscopy (SEM) and optical profilometer analysis confirm a similar coating morphology and roughness for all studied coatings, whereas the coating stability can be tailored with composition and is probed by insertion and dissections experiments in bovine bone with coated zirconia screw implants. An increasing content of calcium phosphate (CP) resulted in a decrease of mechanical and chemical stability, while the bioactivity increased in simulated body fluid (SBF). In vitro experiments with human osteoblast cells (HOB) revealed that the cells grew well on all samples but are affected by dissolution behavior of the studied coatings. This work demonstrates the overall good mechanical strength, the excellent interfacial bonding and the bioactivity potential of coatings with higher TZ contents, which provide a highly interesting coating for dental implants. - Highlights: • Different ratios of zirconia (TZ) and calcium phosphate (CP) were deposited on zirconia substrates. • Enhancement of TZ content in mixed coatings increased coating stability. • Enhancement of CP content in mixed coatings increased bioactivity. • All tested coating compositions were non-toxic

Mixed zirconia calcium phosphate coatings for dental implants: Tailoring coating stability and bioactivity potential

Energy Technology Data Exchange (ETDEWEB)

Pardun, Karoline [University of Bremen, Advanced Ceramics, Am Biologischen Garten 2, 28359 Bremen (Germany); Treccani, Laura, E-mail: treccani@uni-bremen.de [University of Bremen, Advanced Ceramics, Am Biologischen Garten 2, 28359 Bremen (Germany); Volkmann, Eike [University of Bremen, Advanced Ceramics, Am Biologischen Garten 2, 28359 Bremen (Germany); Streckbein, Philipp [University Hospital, Justus-Liebig-University Giessen, Department of Cranio-Maxillo-Facial Surgery, Klinikstrasse 33, 35385 Giessen (Germany); Heiss, Christian [University Hospital of Giessen-Marburg, Department of Trauma Surgery, Rudolf-Buchheim-Strasse 7, 35385 Giessen, Germany, (Germany); Laboratory of Experimental Surgery, Kerkraderstrasse 9, 35392 Giessen (Germany); Destri, Giovanni Li; Marletta, Giovanni [Laboratory for Molecular Surfaces and Nanotechnology (LAMSUN), Department of Chemistry, University of Catania and CSGI, Viale A. Doria 6, 95125 Catania (Italy); Rezwan, Kurosch [University of Bremen, Advanced Ceramics, Am Biologischen Garten 2, 28359 Bremen (Germany)

2015-03-01

Enhanced coating stability and adhesion are essential for long-term success of orthopedic and dental implants. In this study, the effect of coating composition on mechanical, physico-chemical and biological properties of coated zirconia specimens is investigated. Zirconia discs and dental screw implants are coated using the wet powder spraying (WPS) technique. The coatings are obtained by mixing yttria-stabilized zirconia (TZ) and hydroxyapatite (HA) in various ratios while a pure HA coating served as reference material. Scanning electron microscopy (SEM) and optical profilometer analysis confirm a similar coating morphology and roughness for all studied coatings, whereas the coating stability can be tailored with composition and is probed by insertion and dissections experiments in bovine bone with coated zirconia screw implants. An increasing content of calcium phosphate (CP) resulted in a decrease of mechanical and chemical stability, while the bioactivity increased in simulated body fluid (SBF). In vitro experiments with human osteoblast cells (HOB) revealed that the cells grew well on all samples but are affected by dissolution behavior of the studied coatings. This work demonstrates the overall good mechanical strength, the excellent interfacial bonding and the bioactivity potential of coatings with higher TZ contents, which provide a highly interesting coating for dental implants. - Highlights: • Different ratios of zirconia (TZ) and calcium phosphate (CP) were deposited on zirconia substrates. • Enhancement of TZ content in mixed coatings increased coating stability. • Enhancement of CP content in mixed coatings increased bioactivity. • All tested coating compositions were non-toxic.

Structural features of spin-coated thin films of binary AsxS100−x chalcogenide glass system

International Nuclear Information System (INIS)

Cook, J.; Slang, S.; Golovchak, R.; Jain, H.; Vlcek, M.; Kovalskiy, A.

2015-01-01

Spin-coating technology offers a convenient method for fabricating photostable chalcogenide glass thin films that are especially attractive for applications in IR optics. In this paper we report the structure of spin-coated As x S 100−x (x = 30, 35, 40) thin films as determined using high resolution X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy, especially in relation to composition (i.e. As/S ratio) and preparation process variables. It was observed that As atoms during preparation have a tendency to precipitate out in close to stoichiometric compositions. The mechanism of bonding between the inorganic matrix and organic residuals is discussed based on the experimental data. A weak interaction between S ions and amine-based clusters is proposed as the basis of structural organization of the organic–inorganic interface. - Highlights: • As–S spin-coated chalcogenide thin films with different As/S were fabricated. • XPS measurements support the cluster-like structure of spin-coated films. • As 2 O 3 was confirmed as the composition of precipitate formed during dissolution. • Lack of As–As bonds explains the observed photostability of the thin films

Antibacterial polymer coatings.

Energy Technology Data Exchange (ETDEWEB)

Wilson, Mollye C.; Allen, Ashley N.; Barnhart, Meghan; Tucker, Mark David; Hibbs, Michael R.

2009-09-01

A series of poly(sulfone)s with quaternary ammonium groups and another series with aldehyde groups are synthesized and tested for biocidal activity against vegetative bacteria and spores, respectively. The polymers are sprayed onto substrates as coatings which are then exposed to aqueous suspensions of organisms. The coatings are inherently biocidal and do not release any agents into the environment. The coatings adhere well to both glass and CARC-coated coupons and they exhibit significant biotoxicity. The most effective quaternary ammonium polymers kills 99.9% of both gram negative and gram positive bacteria and the best aldehyde coating kills 81% of the spores on its surface.

Stripping methods studies for HVOF WC-10Co-4Cr coating removal

Science.gov (United States)

Menini, Richard; Salah, Nihad Ben; Nciri, Rachid

2004-04-01

The use of high-velocity oxyfuel (HVOF) cermet coatings is considered to be a valuable and innovative alternative technology to replace Cr(VI) electroplating. Among others, a WC-10Co-4Cr coating is one of the best choices for landing gear components due to its excellent tribology and corrosion properties. The stripping process of such a cermet coating was studied due to its importance for the repair and overhaul of landing gear components. Stripping solutions fulfill the following criteria: keep substrate integrity; exhibit a high strip rate (SR); lead to uniform dissolution; show no galvanic corrosion; and be environmentally friendly. Three different high-strength steel substrates (4340, 300M, and Aermet100) were studied. Five different stripping solutions were selected for the electrochemical study. Only three met the targeted criteria: the meta-nitrobenzane sulfonate-sodium cyanide solution; the Rochelle salt; and a commercial nickel stripper. It was found that the process must be electrolytic, and that ultrasonic agitation is needed to enhance the overall mass transport and removal of WC particles and metallic matrix residues. When choosing the most efficient solution and conditions, the SR was found to be as high as 162 µm h-1, which is a very acceptable SR for productivity sake.

Comparison of TiC coating and TD coating in actual application

International Nuclear Information System (INIS)

Kim, S.K.; Yoo, J.K.

1995-01-01

Large blocks of SKD-11 were treated by CVD-TiC coating process, TD coating process, TD coating process after vacuum heat treating, and vacuum heat treating. Amount of deformation was measured and compared to find the process which gives the least deformation. Wear tests were carried out for specimens treated by each process. Application of CVD-TiC and TD coating to the automotive press mold was studied

A missense mutation in melanocortin 1 receptor is associated with the red coat colour in donkeys.

Science.gov (United States)

Abitbol, M; Legrand, R; Tiret, L

2014-12-01

The seven donkey breeds recognised by the French studbook are characterised by few coat colours: black, bay and grey. Normand bay donkeys seldom give birth to red foals, a colour more commonly seen and recognised in American miniature donkeys. Red resembles the equine chestnut colour, previously attributed to a mutation in the melanocortin 1 receptor gene (MC1R). We used a panel of 124 donkeys to identify a recessive missense c.629T>C variant in MC1R that showed a perfect association with the red coat colour. This variant leads to a methionine to threonine substitution at position 210 in the protein. We showed that methionine 210 is highly conserved among vertebrate melanocortin receptors. Previous in silico and in vitro analyses predicted this residue to lie within a functional site. Our in vivo results emphasised the pivotal role played by this residue, the alteration of which yielded a phenotype fully compatible with a loss of function of MC1R. We thus propose to name the c.629T>C allele in donkeys the e allele, which further enlarges the panel of recessive MC1R loss-of-function alleles described in animals and humans. © 2014 Stichting International Foundation for Animal Genetics.

Effects of Bond Coating on NiCrBSi-Mo Composite Functional Coating Properties in Plasma Spraying NiCrBSi-Mo/Ni Coating

OpenAIRE

DU Ji-yu; LI Fang-yi; LU Hai-yang; SHANG Jian-tong; LI Zhen

2017-01-01

Nickel-based bond coating and composite functional coating were sprayed on leaf blade steel material FV520B successively by using air plasma spraying system. NiCrBSi-Mo powder deposition rate, coating porosity, bonding strength and surface hardness were tested. The results indicate that, for the NiCrBSi-Mo/Ni coating, bond coating with 180-220μm thickness can improve NiCrBSi-Mo powder deposition rate while the surface coating with lower porosity, higher bonding strength and high hardness is p...

Convergent Evolution of Slick Coat in Cattle through Truncation Mutations in the Prolactin Receptor

Directory of Open Access Journals (Sweden)

Laercio R. Porto-Neto

2018-02-01

Full Text Available Evolutionary adaptations are occasionally convergent solutions to the same problem. A mutation contributing to a heat tolerance adaptation in Senepol cattle, a New World breed of mostly European descent, results in the distinct phenotype known as slick, where an animal has shorter hair and lower follicle density across its coat than wild type animals. The causal variant, located in the 11th exon of prolactin receptor, produces a frameshift that results in a truncated protein. However, this mutation does not explain all cases of slick coats found in criollo breeds. Here, we obtained genome sequences from slick cattle of a geographically distinct criollo breed, namely Limonero, whose ancestors were originally brought to the Americas by the Spanish. These data were used to identify new causal alleles in the 11th exon of the prolactin receptor, two of which also encode shortened proteins that remove a highly conserved tyrosine residue. These new mutations explained almost 90% of investigated cases of animals that had slick coats, but which also did not carry the Senepol slick allele. These results demonstrate convergent evolution at the molecular level in a trait important to the adaptation of an animal to its environment.

In-situ phosphatizing coatings for aerospace, OEM and coil coating applications

Science.gov (United States)

Neuder, Heather Aurelia

The current metal coating process is a multi-step process. The surface is cleaned, primered, dried and then painted. The process is labor intensive and time consuming. The wash primer is a conversion coating, which prepares metal surface for better paint adhesion. The wash primers currently used often contain hexavalent chromium (Cr6+), which seals the pores in the conversion coating. The presence of hexavalent chromium, a known carcinogen, and volatile organic compounds (VOCs) make waste disposal expensive and pose dangers to workers. The novel technique of in-situ phosphatizing coating (ISPC) is a single-step, chrome-free alternative to the present coating practice. Formulation of an ISPC involves predispersal of an in-situ phosphatizing reagent (ISPR) into the paint system to form a stable formulation. The ISPR reacts with the metal surface and bonds with the paint film simultaneously, which eliminates the need for a conversion coating. In acid catalyzed paint systems, such as polyester-melamine paints, the ISPR also catalyzes cross-linking reactions between the melamine and the polyester polyols. ISPCs are formulated using commercially available coating systems including: polyester-melamine, two-component epoxy, polyurethane and high-hydroxy content polyester-melamine coil coating. The ISPCs are applied to metal substrates and their performances are evaluated using electrochemical, thermal and standard American Society for Testing and Materials (ASTM) testing methods. In addition, ISPCs were designed and formulated based on: (1) phosphate chemistry, (2) polymer chemistry, (3) sol-gel chemistry, and (4) the ion-exchange principle. Organo-functionalized silanes, which serve as excellent coupling and dispersion agents, are incorporated into the optimized ISPC formula and evaluated using standard ASTM testing methods and electrochemical spectroscopy. Also, an ion-exchange pigment, which leads to better adhesion by forming a mixed metal silicate surface, is

Cold-Sprayed AZ91D Coating and SiC/AZ91D Composite Coatings

Directory of Open Access Journals (Sweden)

Yingying Wang

2018-03-01

Full Text Available As an emerging coating building technique, cold spraying has many advantages to elaborate Mg alloy workpieces. In this study, AZ91D coatings and AZ91D-based composite coatings were deposited using cold spraying. Coatings were prepared using different gas temperatures to obtain the available main gas temperature. Compressed air was used as the accelerating gas, and although magnesium alloy is oxidation-sensitive, AZ91D coatings with good performance were obtained. The results show that dense coatings can be fabricated until the gas temperature is higher than 500 °C. The deposition efficiency increases greatly with the gas temperature, but it is lower than 10% for all coating specimens. To analyze the effects of compressed air on AZ91D powder particles and the effects of gas temperature on coatings, the phase composition, porosity, cross-sectional microstructure, and microhardness of coatings were characterized. X-ray diffraction and oxygen content analysis clarified that no phase transformation or oxidation occurred on AZ91D powder particles during cold spraying processes with compressed air. The porosity of AZ91D coatings remained between 3.6% and 3.9%. Impact melting was found on deformed AZ91D particles when the gas temperature increased to 550 °C. As-sprayed coatings exhibit much higher microhardness than as-casted bulk magnesium, demonstrating the dense structure of cold-sprayed coatings. To study the effects of ceramic particles on cold-sprayed AZ91D coatings, 15 vol % SiC powder particles were added into the feedstock powder. Lower SiC content in the coating than in the feedstock powder means that the deposition efficiency of the SiC powder particles is lower than the deposition efficiency of AZ91D particles. The addition of SiC particles reduces the porosity and increases the microhardness of cold-sprayed AZ91D coatings. The corrosion behavior of AZ91D coating and SiC reinforced AZ91D composite coating were examined. The Si

Hard coatings

International Nuclear Information System (INIS)

Dan, J.P.; Boving, H.J.; Hintermann, H.E.

1993-01-01

Hard, wear resistant and low friction coatings are presently produced on a world-wide basis, by different processes such as electrochemical or electroless methods, spray technologies, thermochemical, CVD and PVD. Some of the most advanced processes, especially those dedicated to thin film depositions, basically belong to CVD or PVD technologies, and will be looked at in more detail. The hard coatings mainly consist of oxides, nitrides, carbides, borides or carbon. Over the years, many processes have been developed which are variations and/or combinations of the basic CVD and PVD methods. The main difference between these two families of deposition techniques is that the CVD is an elevated temperature process (≥ 700 C), while the PVD on the contrary, is rather a low temperature process (≤ 500 C); this of course influences the choice of substrates and properties of the coating/substrate systems. Fundamental aspects of the vapor phase deposition techniques and some of their influences on coating properties will be discussed, as well as the very important interactions between deposit and substrate: diffusions, internal stress, etc. Advantages and limitations of CVD and PVD respectively will briefly be reviewed and examples of applications of the layers will be given. Parallel to the development and permanent updating of surface modification technologies, an effort was made to create novel characterisation methods. A close look will be given to the coating adherence control by means of the scratch test, at the coating hardness measurement by means of nanoindentation, at the coating wear resistance by means of a pin-on-disc tribometer, and at the surface quality evaluation by Atomic Force Microscopy (AFM). Finally, main important trends will be highlighted. (orig.)

Highly sensitive and selective colorimetric detection of cartap residue in agricultural products.

Science.gov (United States)

Liu, Wei; Zhang, Daohong; Tang, Yafan; Wang, Yashan; Yan, Fei; Li, Zhonghong; Wang, Jianlong; Zhou, H Susan

2012-11-15

The residue of pesticide has posed a serious threat to human health. Fast, broad-spectrum detection methods are necessary for on-site screening of various types of pesticides. With citrate-coated Au nanoparticles (Au NPs) as colorimetric probes, a visual and spectrophotometric method for rapid assay of cartap, which is one of the most important pesticides in agriculture, is reported for the first time. Based on the color change of Au colloid solution from wine-red to blue resulting from the aggregation of Au NPs, cartap could be detected in the concentration range of 0.05-0.6 mg/kg with a low detection limit of 0.04 mg/kg, which is much lower than the strictest cartap safety requirement of 0.1 mg/kg. Due to the limited research on the rapid detection of cartap based on Au NPs, the performance of the present method was evaluated through aggregation kinetics, interference influence, and sample pretreatment. To further demonstrate the selectivity and applicability of the method, cartap detection is realized in cabbage and tea with excellent analyte concentration recovery. These results demonstrate that the present method provides an easy and effective way to analyze pesticide residue in common products, which is of benefit for the rapid risk evaluation and on-site screening of pesticide residue. Copyright © 2012 Elsevier B.V. All rights reserved.

Anticorrosive coatings: a review

DEFF Research Database (Denmark)

Sørensen, Per Aggerholm; Kiil, Søren; Dam-Johansen, Kim

2009-01-01

of volatile organic compounds (VOCs) have caused significant changes in the anticorrosive coating industry. The requirement for new VOC-compliant coating technologies means that coating manufacturers can no longer rely on the extensive track record of their time-served products to convince consumers...... of their suitability for use. An important aspect in the development of new VOC-compliant, high-performance anticorrosive coating systems is a thorough knowledge of the components in anticorrosive coatings, their interactions, their advantages and limitations, as well as a detailed knowledge on the failure modes......, and inhibitive coatings are outlined. In the past decades, several alternatives to organic solvent-borne coatings have reached the commercial market. This review also presents some of these technologies and discusses some of their advantages and limitations. Finally, some of the mechanisms leading to degradation...

Charged-particle coating

International Nuclear Information System (INIS)

Johnson, W.L.; Crane, J.K.; Hendricks, C.D.

1980-01-01

Advanced target designs require thicker (approx. 300 μm) coatings and better surface finishes that can be produced with current coating techniques. An advanced coating technique is proposed to provide maximum control of the coating flux and optimum manipulation of the shell during processing. In this scheme a small beam of ions or particles of known incident energy are collided with a levitated spherical mandrel. Precise control of the incident energy and angle of the deposition flux optimizes the control of the coating morphology while controlled rotation and noncontact support of the shell minimizes the possibility of particulate or damage generated defects. Almost infinite variability of the incident energy and material in this process provides increased flexibility of the target designs which can be physically realized

Comparison of additive amount used in spin-coated and roll-coated organic solar cells

DEFF Research Database (Denmark)

Cheng, Pei; Lin, Yuze; Zawacka, Natalia Klaudia

2014-01-01

All-polymer and polymer/fullerene inverted solar cells were fabricated by spin-coating and roll-coating processes. The spin-coated small-area (0.04 cm(2)) devices were fabricated on indium tin oxide (ITO) coated glass substrates in nitrogen. The roll-coated large-area (1.0 cm(2)) devices were...

Coated particle waste form development

International Nuclear Information System (INIS)

Oma, K.H.; Buckwalter, C.Q.; Chick, L.A.

1981-12-01

Coated particle waste forms have been developed as part of the multibarrier concept at Pacific Northwest Laboratory under the Alternative Waste Forms Program for the Department of Energy. Primary efforts were to coat simulated nuclear waste glass marbles and ceramic pellets with low-temperature pyrolytic carbon (LT-PyC) coatings via the process of chemical vapor deposition (CVD). Fluidized bed (FB) coaters, screw agitated coaters (SAC), and rotating tube coaters were used. Coating temperatures were reduced by using catalysts and plasma activation. In general, the LT-PyC coatings did not provide the expected high leach resistance as previously measured for carbon alone. The coatings were friable and often spalled off the substrate. A totally different concept, thermal spray coating, was investigated at PNL as an alternative to CVD coating. Flame spray, wire gun, and plasma gun systems were evaluated using glass, ceramic, and metallic coating materials. Metal plasma spray coatings (Al, Sn, Zn, Pb) provided a two to three orders-of-magnitude increase in chemical durability. Because the aluminum coatings were porous, the superior leach resistance must be due to either a chemical interaction or to a pH buffer effect. Because they are complex, coated waste form processes rank low in process feasibility. Of all the possible coated particle processes, plasma sprayed marbles have the best rating. Carbon coating of pellets by CVD ranked ninth when compared with ten other processes. The plasma-spray-coated marble process ranked sixth out of eleven processes

Friction surfaced Stellite6 coatings

International Nuclear Information System (INIS)

Rao, K. Prasad; Damodaram, R.; Rafi, H. Khalid; Ram, G.D. Janaki; Reddy, G. Madhusudhan; Nagalakshmi, R.

2012-01-01

Solid state Stellite6 coatings were deposited on steel substrate by friction surfacing and compared with Stellite6 cast rod and coatings deposited by gas tungsten arc and plasma transferred arc welding processes. Friction surfaced coatings exhibited finer and uniformly distributed carbides and were characterized by the absence of solidification structure and compositional homogeneity compared to cast rod, gas tungsten arc and plasma transferred coatings. Friction surfaced coating showed relatively higher hardness. X-ray diffraction of samples showed only face centered cubic Co peaks while cold worked coating showed hexagonally close packed Co also. - Highlights: ► Stellite6 used as coating material for friction surfacing. ► Friction surfaced (FS) coatings compared with casting, GTA and PTA processes. ► Finer and uniformly distributed carbides in friction surfaced coatings. ► Absence of melting results compositional homogeneity in FS Stellite6 coatings.

Effects of post-heat treatment on microstructure and properties of laser cladded composite coatings on titanium alloy substrate

Science.gov (United States)

Li, G. J.; Li, J.; Luo, X.

2015-01-01

The composite coatings were produced on the Ti6Al4V alloy substrate by laser cladding. Subsequently, the coatings were heated at 500 °C for 1 h and 2 h and then cooled in air. Effects of post-heat treatment on microstructure, microhardness and fracture toughness of the coatings were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), optical microscopy (OM). Wear resistance of the coatings was evaluated under the dry sliding reciprocating friction condition at room temperature. The results indicated that the coatings mainly consist of a certain amount of coarse white equiaxed WC particles surrounded by the white-bright W2C, a great deal of fine dark spherical TiC particles and the matrix composed of the α(Ti), Ti2Ni and TiNi phases. Effects of the post-heat treatment on phase constituents and microstructure of the coatings were almost negligible due to the low temperature. However, the post-heat treatment could decrease the residual stress and increase fracture toughness of the coatings, and fracture toughness of the coatings was improved from 2.77 MPa m1/2 to 3.80 MPa m1/2 and 4.43 MPa m1/2 with the heat treatment for 1 h and 2 h, respectively. The mutual role would contribute to the reduction in cracking susceptibility. Accompanied with the increase in fracture toughness, microhardness of the coatings was reduced slightly. The dominant wear mechanism for all the coatings was abrasive wear, characterized by micro-cutting or micro-plowing. The heat treatment could significantly decrease the average friction coefficient and reduce the fluctuation of the friction coefficient with the change in sliding time. The appropriate heat treatment time (approximately 1 h) had a minimal effect on wear mass loss and volume loss. Moreover, the improvement in fracture toughness will also be beneficial to wear resistance of the coatings under the long service.

Silicates Eroded under Simulated Martian Conditions Effectively Kill Bacteria-A Challenge for Life on Mars.

Science.gov (United States)

Bak, Ebbe N; Larsen, Michael G; Moeller, Ralf; Nissen, Silas B; Jensen, Lasse R; Nørnberg, Per; Jensen, Svend J K; Finster, Kai

2017-01-01

The habitability of Mars is determined by the physical and chemical environment. The effect of low water availability, temperature, low atmospheric pressure and strong UV radiation has been extensively studied in relation to the survival of microorganisms. In addition to these stress factors, it was recently found that silicates exposed to simulated saltation in a Mars-like atmosphere can lead to a production of reactive oxygen species. Here, we have investigated the stress effect induced by quartz and basalt abraded in Mars-like atmospheres by examining the survivability of the three microbial model organisms Pseudomonas putida, Bacillus subtilis , and Deinococcus radiodurans upon exposure to the abraded silicates. We found that abraded basalt that had not been in contact with oxygen after abrasion killed more than 99% of the vegetative cells while endospores were largely unaffected. Exposure of the basalt samples to oxygen after abrasion led to a significant reduction in the stress effect. Abraded quartz was generally less toxic than abraded basalt. We suggest that the stress effect of abraded silicates may be caused by a production of reactive oxygen species and enhanced by transition metal ions in the basalt leading to hydroxyl radicals through Fenton-like reactions. The low survivability of the usually highly resistant D. radiodurans indicates that the effect of abraded silicates, as is ubiquitous on the Martian surface, would limit the habitability of Mars as well as the risk of forward contamination. Furthermore, the reactivity of abraded silicates could have implications for future manned missions, although the lower effect of abraded silicates exposed to oxygen suggests that the effects would be reduced in human habitats.

Silicates Eroded under Simulated Martian Conditions Effectively Kill Bacteria—A Challenge for Life on Mars

Directory of Open Access Journals (Sweden)

Ebbe N. Bak

2017-09-01

Full Text Available The habitability of Mars is determined by the physical and chemical environment. The effect of low water availability, temperature, low atmospheric pressure and strong UV radiation has been extensively studied in relation to the survival of microorganisms. In addition to these stress factors, it was recently found that silicates exposed to simulated saltation in a Mars-like atmosphere can lead to a production of reactive oxygen species. Here, we have investigated the stress effect induced by quartz and basalt abraded in Mars-like atmospheres by examining the survivability of the three microbial model organisms Pseudomonas putida, Bacillus subtilis, and Deinococcus radiodurans upon exposure to the abraded silicates. We found that abraded basalt that had not been in contact with oxygen after abrasion killed more than 99% of the vegetative cells while endospores were largely unaffected. Exposure of the basalt samples to oxygen after abrasion led to a significant reduction in the stress effect. Abraded quartz was generally less toxic than abraded basalt. We suggest that the stress effect of abraded silicates may be caused by a production of reactive oxygen species and enhanced by transition metal ions in the basalt leading to hydroxyl radicals through Fenton-like reactions. The low survivability of the usually highly resistant D. radiodurans indicates that the effect of abraded silicates, as is ubiquitous on the Martian surface, would limit the habitability of Mars as well as the risk of forward contamination. Furthermore, the reactivity of abraded silicates could have implications for future manned missions, although the lower effect of abraded silicates exposed to oxygen suggests that the effects would be reduced in human habitats.

The Influence of Nano-Fibrillated Cellulose as a Coating Component in Paper Coating

Directory of Open Access Journals (Sweden)

Yaxi Xu

2016-03-01

Full Text Available This work investigates nano-fibrillated cellulose (NFC as a component in mineral pigment paper coating. In this work, bleached Eucalyptus pulp was pretreated by TEMPO (2,2,6,6-tetramethyl-1-piperdinyloxy-mediated oxidation. The oxidized pulp was then isolated to obtain NFC by sonication. Aqueous coating colors consisting of calcium carbonate, clay, carboxylated butadiene-styrene latex, additives, and NFC were prepared. The rheology of the coating colors and the surface properties of paper coated with NFC containing coating colors were determined. The rheological properties allowed NFC to be used in small amounts under laboratory conditions. Nano-fibrillated cellulose was found to improve the surface strength and smoothness of the coated paper. The water resistance of coated paper, on the other hand, decreased because of the hydrophilicity of NFC.

Thermal stability of double-ceramic-layer thermal barrier coatings with various coating thickness

International Nuclear Information System (INIS)

Dai Hui; Zhong Xinghua; Li Jiayan; Zhang Yanfei; Meng Jian; Cao Xueqiang

2006-01-01

Double-ceramic-layer (DCL) coatings with various thickness ratios composed of YSZ (6-8 wt.% Y 2 O 3 + ZrO 2 ) and lanthanum zirconate (LZ, La 2 Zr 2 O 7 ) were produced by the atmospheric plasma spraying. Chemical stability of LZ in contact with YSZ in DCL coatings was investigated by calcining powder blends at different temperatures. No obvious reaction was observed when the calcination temperature was lower than 1250 deg. C, implying that LZ and YSZ had good chemical applicability for producing DCL coating. The thermal cycling test indicate that the cycling lives of the DCL coatings are strongly dependent on the thickness ratio of LZ and YSZ, and the coatings with YSZ thickness between 150 and 200 μm have even longer lives than the single-layer YSZ coating. When the YSZ layer is thinner than 100 μm, the DCL coatings failed in the LZ layer close to the interface of YSZ layer and LZ layer. For the coatings with the YSZ thickness above 150 μm, the failure mainly occurs at the interface of the YSZ layer and the bond coat

Influence of Deposition Conditions on Fatigue Properties of Martensitic Stainless Steel with Tin Film Coated by Arc Ion Plating Method

Science.gov (United States)

Fukui, Satoshi; Yonekura, Daisuke; Murakami, Ri-Ichi

The surface properties like roughness etc. strongly influence the fatigue strength of high-tensile steel. To investigate the effect of surface condition and TiN coating on the fatigue strength of high-strength steel, four-point bending fatigue tests were carried out for martensitic stainless steel with TiN film coated using arc ion plating (AIP) method. This study, using samples that had been polished under several size of grind particle, examines the influence of pre-coating treatment on fatigue properties. A 2-µm-thick TiN film was deposited onto the substrate under three kinds of polishing condition. The difference of the hardness originated in the residual stress or thin deformation layer where the difference of the size of grinding particle of the surface polishing. And it leads the transformation of the interface of the substrate and the TiN film and improves fatigue limit.

Quality of Coated Particles : Physical - Mechanical Characterization of Polymeric Film Coatings

NARCIS (Netherlands)

Perfetti, G.

2012-01-01

All coated particle producers, when applying the coating layer(s) would like to know precisely what is the best coating system to use in order to answer customer’s requests. It is, therefore, of very high relevance for many industries, to have a clear understanding of what are the parameters I need

Industrial Wastes as Alternative Mineral Addition in Portland Cement and as Aggregate in Coating Mortars

OpenAIRE

Oliveira, Kamilla Almeida; Nazário, Bruna Inácio; Oliveira, Antonio Pedro Novaes de; Hotza, Dachamir; Raupp-Pereira, Fabiano

2017-01-01

This paper presents an evaluation study of wastes from pulp and paper as well as construction and demolition industries for application in cement-based materials. The alternative raw materials were used as a source of calcium carbonate (CaCO3) and as pozzolanic material (water-reactive SiO2) in partial replacement of Portland cement. In addition to the hydraulic binder, coating mortars were composed by combining the pulp and paper fluidized bed sand residue with construction and demolition wa...

A parametric study of the microstructural, mechanical and tribological properties of PACVD TiN coatings

DEFF Research Database (Denmark)

Mogensen, K.S.; Thomsen, N.B.; Eskildsen, S.S.

1998-01-01

deposition chamber were investigated. The process parameters, i.e, voltage, pressure, and flows of H-2, Ar, N, and TiCl4, were varied. The microstructural, mechanical and tribological properties of the coatings were investigated using X-ray diffraction, scanning electron microscopy, transmission electron...... microscopy, nanoindentation, pin-on-disc measurements and Rutherford backscattering spectrometry. The residual stress level and hardness varied significantly with changes in the process parameters, whereas the tribological properties displayed only minor variations. (C) 1998 Elsevier Science S.A....

Experimental evaluation of coating delamination in vinyl coated metal forming

International Nuclear Information System (INIS)

Son, Young Ki; Lee, Chan Joo; Kim, Byung Min; Lee, Jung Min; Byoen, Sang Doek; Lee, Soen Bong

2012-01-01

In this paper, a new evaluation and prediction method for coating delamination during sheet metal forming is presented. On the basis of the forming limit diagram (FLD), the current study evaluates the delamination of PET coating by using a cross cut specimen, dome test, and rectangular cup drawing test. Dome test specimens were subjected to biaxial, plane strain, and uniaxial deformation modes. Rectangular cup drawing test specimens were subjected to the deep drawing deformation mode, and compression deformation mode. A vinyl coated metal (VCM) sheet consists of three layers of polymer on the sheet metals: a protective film, a PET layer and a PVC layer. The areas with coating delamination were identified, and the results of the evaluation were plotted according to major and minor strain values, depicting coating delamination. The constructed delamination limit diagram (DLD) can be used to determine the forming limit of VCM during the complex press forming process. ARGUS (GOM) was employed to identify the strain value and deformation mode of the delaminated surface after the press forming. After identifying the areas of delamination, the DLD of the PET coating can be constructed in a format similar to that of the FLD. The forming limit of the VCM sheet can be evaluated using the superimposition of the delamination limit strain of the coating onto the FLD of VCM sheet. The experimental results showed that the proposed test method will support the sheet metal forming process design for VCM sheets. The assessment method presented in this study can be used to determine the delamination limit strain under plastic deformation of other polymer coated metals. The experimental results suggested that the proposed testing method is effective in evaluating delamination for specific applications

Experimental evaluation of coating delamination in vinyl coated metal forming

Energy Technology Data Exchange (ETDEWEB)

Son, Young Ki; Lee, Chan Joo; Kim, Byung Min [Pusan National Univ., Busan (Korea, Republic of); Lee, Jung Min [Korea Institute of Industrial Technology, Busan (Korea, Republic of); Byoen, Sang Doek [HA Digital Engineering Gr., Seongsan Gu (Korea, Republic of); Lee, Soen Bong [Keimyung Univ., Daegu (Korea, Republic of)

2012-10-15

In this paper, a new evaluation and prediction method for coating delamination during sheet metal forming is presented. On the basis of the forming limit diagram (FLD), the current study evaluates the delamination of PET coating by using a cross cut specimen, dome test, and rectangular cup drawing test. Dome test specimens were subjected to biaxial, plane strain, and uniaxial deformation modes. Rectangular cup drawing test specimens were subjected to the deep drawing deformation mode, and compression deformation mode. A vinyl coated metal (VCM) sheet consists of three layers of polymer on the sheet metals: a protective film, a PET layer and a PVC layer. The areas with coating delamination were identified, and the results of the evaluation were plotted according to major and minor strain values, depicting coating delamination. The constructed delamination limit diagram (DLD) can be used to determine the forming limit of VCM during the complex press forming process. ARGUS (GOM) was employed to identify the strain value and deformation mode of the delaminated surface after the press forming. After identifying the areas of delamination, the DLD of the PET coating can be constructed in a format similar to that of the FLD. The forming limit of the VCM sheet can be evaluated using the superimposition of the delamination limit strain of the coating onto the FLD of VCM sheet. The experimental results showed that the proposed test method will support the sheet metal forming process design for VCM sheets. The assessment method presented in this study can be used to determine the delamination limit strain under plastic deformation of other polymer coated metals. The experimental results suggested that the proposed testing method is effective in evaluating delamination for specific applications.

ATHENA optimized coating design

DEFF Research Database (Denmark)

Ferreira, Desiree Della Monica; Christensen, Finn Erland; Jakobsen, Anders Clemen

2012-01-01

The optimization of coating design for the ATHENA mission si described and the possibility of increasing the telescope effective area in the range between 0.1 and 10 keV is investigated. An independent computation of the on-axis effective area based on the mirror design of ATHENA is performed...... in order to review the current coating baseline. The performance of several material combinations, considering a simple bi-layer, simple multilayer and linear graded multilayer coatings are tested and simulation of the mirror performance considering both the optimized coating design and the coating...

Preparation of sustained release capsules by electrostatic dry powder coating, using traditional dip coating as reference.

Science.gov (United States)

Yang, Yan; Shen, Lian; Yuan, Feng; Fu, Hui; Shan, Weiguang

2018-05-30

Lately, a great deal of attention is being paid to capsule coating, since the coat protects active pharmaceutical ingredients (APIs) from damage, as is in the case of tablet and pellet. However, moisture and heat sensitivity of gelatin shells make it challenging to coat capsules using the conventional aqueous coating techniques. In an effort to overcome this challenge, the present study aims to coat capsules using two different coating techniques: electrostatic dry powder coating (EDPC) and dip coating (DC). Both capsule coatings and free films were prepared by these two coating techniques, and the effects of coating formulations and processing conditions on the film quality were investigated. The corresponding drug in vitro release and mechanisms were characterized and compared. The results of dissolution tests demonstrated that the drug release behavior of both EDPC and DC coated capsules could be optimized to a sustained release of 24 h, following the Fick's diffusion law. The results of this study suggest that EDPC method is better than DC method for coating capsules, with respect to the higher production efficiency and better stability, indicating that this dry coating technology has promised in gelatin capsule coating applications. Copyright © 2018 Elsevier B.V. All rights reserved.

Low Temperature Powder Coating

Science.gov (United States)

2011-02-09

of volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) • Legacy primers contain hexavalent chrome • Conventional powder coatings...coatings both in laboratory and field service evaluations • LTCPC allows environmental cost reductions through VOC/HAP elimination and hexavalent ... chrome reduction. • The LTCPC process greatly shortens the coating operation (LTCPC cures much more rapidly then conventional wet coatings) resulting in

Seal Technology in Gas Turbine Engines

Science.gov (United States)

1978-08-01

the case inner wall (Fig.. 6 (a) and 7 (a)) und for shrouded rotors between blade shroud and the came (Figs. 6() snd 7(b)) (b) Blade roots and platforms ...work is required to fully validate these rig tests. Abradable coatings and linings used in turbines, produce wear of the fins on the root platforms ...Division of Rolls-Royce Limited for their permission to publish. ILI w% C - IL I L 2-10 1’t 00z It. ’K 0 0 ý - -C u -4% uj % z. 9 0 < m m wz I- 10 wIx u 2

Search for magnetic minerals in Martian rocks: Overview of the Rock Abrasion Tool (RAT) magnet investigation on Spirit and Opportunity

DEFF Research Database (Denmark)

Goetz, W.; Leer, K.; Gunnlaugsson, H.P.

2008-01-01

The Rock Abrasion Tool (RAT) on board the Mars Exploration Rovers (MER) is a grinding tool designed to remove dust coatings and/or weathering rinds from rocks and expose fresh rock material. Four magnets of different strengths that are built into the structure of the RAT have been attracting...... is interpreted as magnetite. The amount of abraded rock material adhering to the magnets varied strongly during the mission and is correlated in a consistent way to the amount of magnetite inferred from Mossbauer spectra for the corresponding rock. The RAT magnet experiment as performed on Opportunity also...

A survey of residual analysis and a new test of residual trend.

Science.gov (United States)

McDowell, J J; Calvin, Olivia L; Klapes, Bryan

2016-05-01

A survey of residual analysis in behavior-analytic research reveals that existing methods are problematic in one way or another. A new test for residual trends is proposed that avoids the problematic features of the existing methods. It entails fitting cubic polynomials to sets of residuals and comparing their effect sizes to those that would be expected if the sets of residuals were random. To this end, sampling distributions of effect sizes for fits of a cubic polynomial to random data were obtained by generating sets of random standardized residuals of various sizes, n. A cubic polynomial was then fitted to each set of residuals and its effect size was calculated. This yielded a sampling distribution of effect sizes for each n. To test for a residual trend in experimental data, the median effect size of cubic-polynomial fits to sets of experimental residuals can be compared to the median of the corresponding sampling distribution of effect sizes for random residuals using a sign test. An example from the literature, which entailed comparing mathematical and computational models of continuous choice, is used to illustrate the utility of the test. © 2016 Society for the Experimental Analysis of Behavior.

In Vitro Evaluation of PCL and P(3HB) as Coating Materials for Selective Laser Melted Porous Titanium Implants.

Science.gov (United States)

Grau, Michael; Matena, Julia; Teske, Michael; Petersen, Svea; Aliuos, Pooyan; Roland, Laura; Grabow, Niels; Murua Escobar, Hugo; Gellrich, Nils-Claudius; Haferkamp, Heinz; Nolte, Ingo

2017-11-23

Titanium is widely used as a bone implant material due to its biocompatibility and high resilience. Since its Young's modulus differs from bone tissue, the resulting "stress shielding" could lead to scaffold loosening. However, by using a scaffold-shaped geometry, the Young's modulus can be adjusted. Also, a porous geometry enables vascularisation and bone ingrowth inside the implant itself. Additionally, growth factors can improve these effects. In order to create a deposit and release system for these factors, the titanium scaffolds could be coated with degradable polymers. Therefore, in the present study, synthetic poly-ε-caprolactone (PCL) and the biopolymer poly(3-hydroxybutyrate) (P(3HB)) were tested for coating efficiency, cell adhesion, and biocompatibility to find a suitable coating material. The underlying scaffold was created from titanium by Selective Laser Melting (SLM) and coated with PCL or P(3HB) via dip coating. To test the biocompatibility, Live Cell Imaging (LCI) as well as vitality and proliferation assays were performed. In addition, cell adhesion forces were detected via Single Cell Force Spectroscopy, while the coating efficiency was observed using environmental scanning electron microscopy (ESEM) and energy-dispersive X-ray (EDX) analyses. Regarding the coating efficiency, PCL showed higher values in comparison to P(3HB). Vitality assays revealed decent vitality values for both polymers, while values for PCL were significantly lower than those for blank titanium. No significant differences could be observed between PCL and P(3HB) in proliferation and cell adhesion studies. Although LCI observations revealed decreasing values in cell number and populated area over time on both polymer-coated scaffolds, these outcomes could be explained by the possibility of coating diluent residues accumulating in the culture medium. Overall, both polymers fulfill the requirements regarding biocompatibility. Nonetheless, since only PCL coating ensured the

In Vitro Evaluation of PCL and P(3HB as Coating Materials for Selective Laser Melted Porous Titanium Implants

Directory of Open Access Journals (Sweden)

Michael Grau

2017-11-01

Full Text Available Titanium is widely used as a bone implant material due to its biocompatibility and high resilience. Since its Young’s modulus differs from bone tissue, the resulting “stress shielding” could lead to scaffold loosening. However, by using a scaffold-shaped geometry, the Young’s modulus can be adjusted. Also, a porous geometry enables vascularisation and bone ingrowth inside the implant itself. Additionally, growth factors can improve these effects. In order to create a deposit and release system for these factors, the titanium scaffolds could be coated with degradable polymers. Therefore, in the present study, synthetic poly-ε-caprolactone (PCL and the biopolymer poly(3-hydroxybutyrate (P(3HB were tested for coating efficiency, cell adhesion, and biocompatibility to find a suitable coating material. The underlying scaffold was created from titanium by Selective Laser Melting (SLM and coated with PCL or P(3HB via dip coating. To test the biocompatibility, Live Cell Imaging (LCI as well as vitality and proliferation assays were performed. In addition, cell adhesion forces were detected via Single Cell Force Spectroscopy, while the coating efficiency was observed using environmental scanning electron microscopy (ESEM and energy-dispersive X-ray (EDX analyses. Regarding the coating efficiency, PCL showed higher values in comparison to P(3HB. Vitality assays revealed decent vitality values for both polymers, while values for PCL were significantly lower than those for blank titanium. No significant differences could be observed between PCL and P(3HB in proliferation and cell adhesion studies. Although LCI observations revealed decreasing values in cell number and populated area over time on both polymer-coated scaffolds, these outcomes could be explained by the possibility of coating diluent residues accumulating in the culture medium. Overall, both polymers fulfill the requirements regarding biocompatibility. Nonetheless, since only PCL

Effect of microstructure on mechanical and tribological properties of TiAlSiN nanocomposite coatings deposited by modulated pulsed power magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Wu, Z.L. [Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); College of Engineering, Hunan Agricultural University/Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China, Changsha 410128 (China); Li, Y.G.; Wu, B. [Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Lei, M.K., E-mail: surfeng@dlut.edu.cn [Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)

2015-12-31

TiAlSiN nanocomposite coatings were deposited in a closed field unbalanced magnetron sputtering system by reactive sputtering from Ti{sub 0.475}Al{sub 0.475}Si{sub 0.05} targets using modulated pulsed power magnetron sputtering (MPPMS) under a floating substrate bias. The ratio of the nitrogen flow rate to the total gas flow rate (f{sub N{sub 2}}) was varied from 0 to 40%. The application of MPPMS as sputtering sources was aimed at generating a high ionization degree of the sputtered material and a high plasma density by using a pulsed high power approach. When f{sub N{sub 2}} = 0%, an amorphous-like structure Ti{sub 0.479}Al{sub 0.454}Si{sub 0.066} coating was deposited with a hardness of 10 GPa. When nitrogen was added, an optimized nanocomposite structure of nc-TiAlN/a-Si{sub 3}N{sub 4} formed in the TiAlSiN coating deposited at f{sub N{sub 2}} = 10%, in which 5–10 nm TiAlN nanocrystallites were embedded in a 2–3 nm thick amorphous Si{sub 3}N{sub 4} matrix. As the f{sub N{sub 2}} was increased up to 40%, the elementary composition of the coatings remained almost the same, but the grain size of nanocrystallites approached to 10–20 nm and the AlN phase gradually precipitated. A maximum hardness (H) of 33.2 GPa, a hardness to the elastic modulus (E) ratio of 0.081 and an H{sup 3}/E*{sup 2} ratio of 0.19 GPa were found in the coating deposited at f{sub N{sub 2}} = 10%. The friction coefficient of the TiAlSiN coatings was around 0.8–0.9 as sliding against a Si{sub 3}N{sub 4} counterpart under a normal load of 0.5 N. A wear rate of 2.0 × 10{sup −5} mm{sup 3} N{sup −1} m{sup −1} was measured in the TiAlSiN coatings deposited at f{sub N{sub 2}} = 20–40%. As only a low residual stress is found in the TiAlSiN coatings, we consider the complete phase separation is responsible for the enhanced mechanical and tribological properties of the nc-TiAlN/a-Si{sub 3}N{sub 4} nanocomposite coatings. - Highlights: • TiAlSiN nanocomposite coatings were prepared by

Metallic coating of microspheres

International Nuclear Information System (INIS)

Meyer, S.F.

1980-01-01

Extremely smooth, uniform metal coatings of micrometer thicknesses on microscopic glass spheres (microspheres) are often needed as targets for inertial confinement fusion (ICF) experiments. The first part of this paper reviews those methods used successfully to provide metal coated microspheres for ICF targets, including magnetron sputtering, electro- and electroless plating, and chemical vapor pyrolysis. The second part of this paper discusses some of the critical aspects of magnetron sputter coating of microspheres, including substrate requirements, the sticking of microspheres during coating (preventing a uniform coating), and the difficulties in growing the desired dense, smooth, uniform microstructure on continuously moving spherical substrates

Coating compositions hardenable by ionization beams

International Nuclear Information System (INIS)

Chaudhari, D.; Haering, E.; Dobbelstein, A.; Hoselmann, W.

1976-01-01

Coating compositions hardenable by ionizing radiation comprise as binding agents a mixture of A. at least 1 unsaturated olefin compound containing urethane groups, and B. at least 1 further unsaturated olefin compound that may be copolymerized. The unsaturated olefin compound A. containing the urethane groups in a reaction product of (a) a compound of the general formula (CHR 1 = CR 2 COOCH 2 CH(OH)CH 2 O CO-)/sub n/R where n is 1 or 2, where R stands for a straight chain or branched alkyl group of valence n, where R 1 is hydrogen, methyl; or the group -COOCH 2 CH(OH)CH 2 OCOR 3 - where R 3 is a monovalent alkyl residue and where R 2 is hydrogen or methyl, and (b) a compound containing at least 1 isocyanate group where the mixture of (A) and (B) may contain conventional additives of the lacquer industry. 6 claims

Tensile bond strength of resin composite repair in vitro using different surface preparation conditionings to an aged CAD/CAM resin nanoceramic.

Science.gov (United States)

Stawarczyk, Bogna; Krawczuk, Andreas; Ilie, Nicoleta

2015-03-01

This study was conducted in order to assess the pretreatment method (air abrasion, both wet and dry, and Al2O3 grinder), the conditioning method (comprised of different adhesive systems), the repair resin composite (low and high modulus of elasticity), the contamination of CoJet air-abraded surfaces with water, and the effect phosphoric acid on the macrotensile bond strength (TBS) to aged CAD/CAM resin nanoceramic (RNC). Aged RNC substrates (LAVA Ultimate, 3M ESPE; N = 900; 10,000 cycles, 5 °C/55 °C) were air-abraded (CoJet 3M ESPE) with and without water contamination or treated with an Al2O3 grinder (Cimara, Voco). Immediately after pretreatment, half of the specimens were additionally cleaned with phosphoric acid, while the rest were only rinsed with water. Four intermediate agents (Futurabond U/VOCO, Scotchbond Universal/3M ESPE, One Coat Bond/Coltène Whaledent, visio.link/bredent) were selected for conditioning the surface, while no conditioned specimens acted as control groups. Specimens were thereafter repaired using two direct resin composites (Arabesk Top and GrandioSo, VOCO), stored for 24 h at 37 °C in H2O, and thermally aged for 10,000 cycles (5 °C/55 °C; n = 15/subgroup). TBS and failure types were determined and evaluated with four- and one-way ANOVA and χ (2) test (p universal adhesives proved to be effective intermediate agents for repairing aged CAD/CAM RNC, while visio.link and Scotchbond Universal performed slightly better than Futurabond U. Phosphoric acid or water contamination of the air-abraded surface does not affect the repair bond strength.

Oxidation of iridium coating on rhenium coated graphite at elevated temperature in stagnated air

International Nuclear Information System (INIS)

Huang, Yongle; Bai, Shuxin; Zhang, Hong; Ye, Yicong

2015-01-01

Highlights: • Continuous and dense Ir coatings were prepared on graphite by electrodepostion. • The purification of the as-prepared Ir coating was higher than about 99.98%. • The Ir/Re/C specimen kept integrity without significant failures after oxidation. • The average oxidation rate of the Ir coating was about 0.219 mg/(cm 2 min). • Penetrating holes at gains boundaries resulted in the failure of the Ir coating. - Abstract: Continuous and dense iridium coatings were prepared on the rhenium coated graphite specimens by electrodeposition. The iridium/rhenium coated graphite (Ir/Re/C) specimens were oxidized at elevated temperatures in stagnated air for 3600 s. The purification of the as-prepared Ir coating was higher than about 99.98% with the main impurity elements Si, Al, Fe and Ru. After oxidation, the Ir/Re/C specimens kept integrity without significant failures and the average oxidation rate was about 0.219 mg/(cm 2 min). Pores were found at the grain boundaries and concentrated to penetrating holes with the growth of Ir grains, which resulted in disastrous failures of the Ir coating

Oxidation of iridium coating on rhenium coated graphite at elevated temperature in stagnated air

Energy Technology Data Exchange (ETDEWEB)

Huang, Yongle; Bai, Shuxin, E-mail: NUDT_MSE_501@163.com; Zhang, Hong; Ye, Yicong

2015-02-15

Highlights: • Continuous and dense Ir coatings were prepared on graphite by electrodepostion. • The purification of the as-prepared Ir coating was higher than about 99.98%. • The Ir/Re/C specimen kept integrity without significant failures after oxidation. • The average oxidation rate of the Ir coating was about 0.219 mg/(cm{sup 2} min). • Penetrating holes at gains boundaries resulted in the failure of the Ir coating. - Abstract: Continuous and dense iridium coatings were prepared on the rhenium coated graphite specimens by electrodeposition. The iridium/rhenium coated graphite (Ir/Re/C) specimens were oxidized at elevated temperatures in stagnated air for 3600 s. The purification of the as-prepared Ir coating was higher than about 99.98% with the main impurity elements Si, Al, Fe and Ru. After oxidation, the Ir/Re/C specimens kept integrity without significant failures and the average oxidation rate was about 0.219 mg/(cm{sup 2} min). Pores were found at the grain boundaries and concentrated to penetrating holes with the growth of Ir grains, which resulted in disastrous failures of the Ir coating.

Image processing of worn and unworn protective coatings of TiAlN and TiN on 100Cr6 steel

DEFF Research Database (Denmark)

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

by a reciprocating wear process in a linear tribo-meter with up to 105 repetitive cycles, leaving the embedded TiN signal layers uncovered at the bottom the wear scars. The worn surfaces were characterized by subsequent image processing. A color detection, by a simple optical imaging system, of the wear scar......-coating to the TiN signal layer. The two different methods, image processing and laser reflectance measurements, lead thus to identical results, showing that image processing by means of color detection or monitoring and laser reflectance are potential techniques for intelligent determination of residual thickness......A model system, consisting of a titanium aluminum nitride (TiAlN) coating on top of an ‘optical’ titanium nitride (TiN) signal layer deposited on 100Cr6 steel substrates, was exposed to an extremely abrasive wear process. The TiAlN top-coatings, of thicknesses of up to 3 µm, were removed...

Effect of substrate bias voltage on tensile properties of single crystal silicon microstructure fully coated with plasma CVD diamond-like carbon film

Science.gov (United States)

Zhang, Wenlei; Hirai, Yoshikazu; Tsuchiya, Toshiyuki; Tabata, Osamu

2018-06-01

Tensile strength and strength distribution in a microstructure of single crystal silicon (SCS) were improved significantly by coating the surface with a diamond-like carbon (DLC) film. To explore the influence of coating parameters and the mechanism of film fracture, SCS microstructure surfaces (120 × 4 × 5 μm3) were fully coated by plasma enhanced chemical vapor deposition (PECVD) of a DLC at five different bias voltages. After the depositions, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermal desorption spectrometry (TDS), surface profilometry, atomic force microscope (AFM) measurement, and nanoindentation methods were used to study the chemical and mechanical properties of the deposited DLC films. Tensile test indicated that the average strength of coated samples was 13.2-29.6% higher than that of the SCS sample, and samples fabricated with a -400 V bias voltage were strongest. The fracture toughness of the DLC film was the dominant factor in the observed tensile strength. Deviations in strength were reduced with increasingly negative bias voltage. The effect of residual stress on the tensile properties is discussed in detail.

Coatings and Tints of Spectacle Lenses

Directory of Open Access Journals (Sweden)

H. Zeki Büyükyıldız

2012-10-01

Full Text Available Spectacle lenses are made of mineral or organic (plastic materials. Various coatings and tints are applied to the spectacle lenses according to the characteristic of the lens material, and for the personal needs and cosmetic purpose. The coatings may be classified in seven groups: 1 Anti-reflection coatings, 2 Hard coatings, 3 Clean coat, 4 Mirror coatings, 5 Color tint coating (one of coloring processes, 6 Photochromic coating (one of photochromic processes, and 7 Anti-fog coatings. Anti-reflection coatings reduce unwanted reflections from the lens surfaces and increase light transmission. Hard coatings are applied for preventing the plastic lens surface from scratches and abrasion. Hard coatings are not required for the mineral lenses due to their hardness. Clean coat makes the lens surface smooth and hydrophobic. Thus, it prevents the adherence of dust, tarnish, and dirt particles on the lens surface. Mirror coatings are applied onto the sunglasses for cosmetic purpose. Color tinted and photochromic lenses are used for sun protection and absorption of the harmful UV radiations. Anti-fog coatings make the lens surface hydrophilic and prevent the coalescence of tiny water droplets on the lens surface that reduces light transmission. (Turk J Ophthalmol 2012; 42: 359-69

Design and Characterization of High-strength Bond Coats for Improved Thermal Barrier Coating Durability

Science.gov (United States)

Jorgensen, David John

High pressure turbine blades in gas turbine engines rely on thermal barrier coating (TBC) systems for protection from the harsh combustion environment. These coating systems consist of a ceramic topcoat for thermal protection, a thermally grown oxide (TGO) for oxidation passivation, and an intermetallic bond coat to provide compatibility between the substrate and ceramic over-layers while supplying aluminum to sustain Al2O 3 scale growth. As turbine engines are pushed to higher operating temperatures in pursuit of better thermal efficiency, the strength of industry-standard bond coats limits the lifetime of these coating systems. Bond coat creep deformation during thermal cycling leads to a failure mechanism termed rumpling. The interlayer thermal expansion differences, combined with TGO-imposed growth stresses, lead to the development of periodic undulations in the bond coat. The ceramic topcoat has low out-of-plane compliance and thus detaches and spalls from the substrate, resulting in a loss of thermal protection and subsequent degradation of mechanical properties. New creep resistant Ni3Al bond coats were designed with improved high-temperature strength to inhibit this type of premature failure at elevated temperatures. These coatings resist rumpling deformation while maintaining compatibility with the other layers in the system. Characterization methods are developed to quantify rumpling and assess the TGO-bond coat interface toughness of experimental systems. Cyclic oxidation experiments at 1163 °C show that the Ni3Al bond coats do not experience rumpling but have faster oxide growth rates and are quicker to spall TGO than the (Pt,Ni)Al benchmark. However, the Ni 3Al coatings outperformed the benchmark by over threefold in TBC system life due to a higher resistance to rumpling (mechanical degradation) while maintaining adequate oxidation passivation. The Ni3Al coatings eventually grow spinel NiAl2O4 on top of the protective Al2O3 layer, which leads to the

Non-Deforming, High-Reflectance X-ray Coatings for Lynx and Other Future Missions

Science.gov (United States)

Windt, David

.1–10 keV band deposited by magnetron sputtering have high density and low roughness, and thus good X-ray performance. However Ir, B4C, and certain other materials have exceedingly high film stress when deposited under conditions for maximum reflectance. Residual film stress in the X-ray reflective coatings can deform thin-shell mirror segments, leading to unacceptable degradation of angular resolution. Coating stress was not an issue for Chandra. But for Lynx, for example, the substrates will be 50x thinner, and so sub-arc-second resolution simply cannot be achieved using thin-shell mirror segments without the development of non-deforming coatings. The second specific aim of this proposal is to develop techniques to mitigate coatingstress-induced deformations in glass and Si shell segments. Two potential solutions will be investigated: a) New deposition methods to control coating thickness uniformity and net film stress in two dimensions will be used to determine if already-developed zero-netstress Ir-based coatings, as well as the new reflective coatings to be developed, can be deposited onto shell segments without inducing unacceptable substrate deformations, a question that has not yet been definitively addressed; if uniform coatings having sufficiently low deformation cannot be realized, then non-uniform coatings will be investigated, where spatial control of net film stress in 2D will compensate for potential non-uniform deformations. If successful, the effectiveness of the approach with more complex interference coatings will also be established. b) A more general (albeit more complex) method of mitigating stress-induced deformations will be investigated, specifically the use of balanced front- and backside coatings, a technique that, if successful, can be used, in principle, with any type of coating (Ir-based, high-energy multilayers, etc.), regardless of its stress state. (The approach is likely incompatible with active correction, however.)

Formation of the outer layer of the Dictyostelium spore coat depends on the inner-layer protein SP85/PsB.

Science.gov (United States)

Metcalf, Talibah; Kelley, Karen; Erdos, Gregory W; Kaplan, Lee; West, Christopher M

2003-02-01

The Dictyostelium spore is surrounded by a 220 microm thick trilaminar coat that consists of inner and outer electron-dense layers surrounding a central region of cellulose microfibrils. In previous studies, a mutant strain (TL56) lacking three proteins associated with the outer layer exhibited increased permeability to macromolecular tracers, suggesting that this layer contributes to the coat permeability barrier. Electron microscopy now shows that the outer layer is incomplete in the coats of this mutant and consists of a residual regular array of punctate electron densities. The outer layer is also incomplete in a mutant lacking a cellulose-binding protein associated with the inner layer, and these coats are deficient in an outer-layer protein and another coat protein. To examine the mechanism by which this inner-layer protein, SP85, contributes to outer-layer formation, various domain fragments were overexpressed in forming spores. Most of these exert dominant negative effects similar to the deletion of outer-layer proteins, but one construct, consisting of a fusion of the N-terminal and Cys-rich C1 domain, induces a dense mat of novel filaments at the surface of the outer layer. Biochemical studies show that the C1 domain binds cellulose, and a combination of site-directed mutations that inhibits its cellulose-binding activity suppresses outer-layer filament induction. The results suggest that, in addition to a previously described early role in regulating cellulose synthesis, SP85 subsequently contributes a cross-bridging function between cellulose and other coat proteins to organize previously unrecognized structural elements in the outer layer of the coat.

Hydroxyapatite/poly(epsilon-caprolactone) double coating on magnesium for enhanced corrosion resistance and coating flexibility.

Science.gov (United States)

Jo, Ji-Hoon; Li, Yuanlong; Kim, Sae-Mi; Kim, Hyoun-Ee; Koh, Young-Hag

2013-11-01

Hydroxyapatite was deposited on pure magnesium (Mg) with a flexible poly(ε-caprolactone) interlayer to reduce the corrosion rate of Mg and enhance coating flexibility. The poly(ε-caprolactone) interlayer was uniformly coated on Mg by a spraying method, followed by hydroxyapatite deposition on the poly(ε-caprolactone) using an aerosol deposition method. In scanning electron microscopy observations, inorganic/organic composite-like structure was observed between the hydroxyapatite and poly(ε-caprolactone) layers, resulting from the collisions of hydroxyapatite particles into the poly(ε-caprolactone) matrix at the initial stage of the aerosol deposition. The corrosion resistance of the coated Mg was examined using potentiodynamic polarization tests. The hydroxyapatite/poly(ε-caprolactone) double coating remarkably improved the corrosion resistance of Mg in Hank's solution. In the in vitro cell tests, the coated Mg showed better cell adhesion compared with the bare Mg due to the reduced corrosion rate and enhanced biocompatibility. The stability and flexibility of hydroxyapatite/poly(ε-caprolactone) double coating was investigated by scanning electron microscopy inspections after the coated Mg was deformed. The hydroxyapatite coating on the poly(ε-caprolactone) interlayer revealed enhanced coating stability and flexibility without cracking or delamination during bending and stretching compared with the hydroxyapatite single coating. These results demonstrated that the hydroxyapatite/poly(ε-caprolactone) double coating significantly improved the surface corrosion resistance of Mg and enhanced coating flexibility for use of Mg as a biodegradable implant.

Coating and curing apparatus and methods

Science.gov (United States)

Brophy, Brenor L; Maghsoodi, Sina; Neyman, Patrick J; Gonsalves, Peter R; Hirsch, Jeffrey G; Yang, Yu S

2015-02-24

Disclosed are coating apparatus including flow coating and roll-coating that may be used for uniform sol-gel coating of substrates such as glass, solar panels, windows or part of an electronic display. Also disclosed are methods for substrate preparation, flow coating and roll coating. Lastly systems and methods for skin curing sol-gel coatings deposited onto the surface of glass substrates using a high temperature air-knife are disclosed.