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Sample records for atmospheric plasma spraying

  1. Effect of Gun Current on Electrical Properties of Atmospheric Plasma-Sprayed Lanthanum Silicate Coatings

    Science.gov (United States)

    Gao, Wei; Liao, Han-Lin; Coddet, Christian

    2013-10-01

    Apatite-type lanthanum silicate (ATLS) electrolyte coatings for use in intermediate-temperature solid oxide fuel cells were deposited by atmospheric plasma spraying (APS). Plasma-sprayed coatings with typical composition La10(SiO4)6O3 exhibiting good densification and high oxide ionic conductivity were obtained by properly adjusting the spraying parameters, particularly the gun current. The highest obtained ionic conductivity value of 3.3 mS/cm at 1,173 K in air is comparable to other ATLS conductors. This work demonstrated empirically that utilization of the APS technique is feasible to synthesize dense La10(SiO4)6O3 electrolyte coatings using gun currents within an unusually broad range.

  2. The Influence of Anode Inner Contour on Atmospheric DC Plasma Spraying Process

    Directory of Open Access Journals (Sweden)

    Kui Wen

    2017-01-01

    Full Text Available In thermal plasma spraying process, anode nozzle is one of the most important components of plasma torch. Its inner contour controls the characteristics of plasma arc/jet, determining the motion and heating behaviors of the in-flight particles and hence influencing the coating quality. In this study, the effects of anode inner contour, standard cylindrical nozzle, and cone-shaped Laval nozzle with conical shape diverging exit (CSL nozzle on the arc voltage, net power, thermal efficiency, plasma jet characteristics, in-flight particle behaviors, and coating properties have been systematically investigated under atmospheric plasma spraying conditions. The results show that the cylindrical nozzle has a higher arc voltage, net power, and thermal efficiency, as well as the higher plasma temperature and velocity at the torch exit, while the CSL nozzle has a higher measured temperature of plasma jet. The variation trends of the plasma jet characteristics for the two nozzles are comparable under various spraying parameters. The in-flight particle with smaller velocity of CSL nozzle has a higher measured temperature and melting fraction. As a result, the coating density and adhesive strength of CSL nozzle are lower than those of cylindrical nozzle, but the deposition efficiency is greatly improved.

  3. Method and Process Development of Advanced Atmospheric Plasma Spraying for Thermal Barrier Coatings

    Science.gov (United States)

    Mihm, Sebastian; Duda, Thomas; Gruner, Heiko; Thomas, Georg; Dzur, Birger

    2012-06-01

    Over the last few years, global economic growth has triggered a dramatic increase in the demand for resources, resulting in steady rise in prices for energy and raw materials. In the gas turbine manufacturing sector, process optimizations of cost-intensive production steps involve a heightened potential of savings and form the basis for securing future competitive advantages in the market. In this context, the atmospheric plasma spraying (APS) process for thermal barrier coatings (TBC) has been optimized. A constraint for the optimization of the APS coating process is the use of the existing coating equipment. Furthermore, the current coating quality and characteristics must not change so as to avoid new qualification and testing. Using experience in APS and empirically gained data, the process optimization plan included the variation of e.g. the plasma gas composition and flow-rate, the electrical power, the arrangement and angle of the powder injectors in relation to the plasma jet, the grain size distribution of the spray powder and the plasma torch movement procedures such as spray distance, offset and iteration. In particular, plasma properties (enthalpy, velocity and temperature), powder injection conditions (injection point, injection speed, grain size and distribution) and the coating lamination (coating pattern and spraying distance) are examined. The optimized process and resulting coating were compared to the current situation using several diagnostic methods. The improved process significantly reduces costs and achieves the requirement of comparable coating quality. Furthermore, a contribution was made towards better comprehension of the APS of ceramics and the definition of a better method for future process developments.

  4. Oxidation Behavior of Titanium Carbonitride Coating Deposited by Atmospheric Plasma Spray Synthesis

    Science.gov (United States)

    Zhu, Lin; He, Jining; Yan, Dianran; Liao, Hanlin; Zhang, Nannan

    2017-10-01

    As a high-hardness and anti-frictional material, titanium carbonitride (TiCN) thick coatings or thin films are increasingly being used in many industrial fields. In the present study, TiCN coatings were obtained by atmospheric plasma spray synthesis or reactive plasma spray. In order to promote the reaction between the Ti particles and reactive gases, a home-made gas tunnel was mounted on a conventional plasma gun to perform the spray process. The oxidation behavior of the TiCN coatings under different temperatures in static air was carefully investigated. As a result, when the temperature was over 700 °C, the coatings suffered from serious oxidation, and finally they were entirely oxidized to the TiO2 phase at 1100 °C. The principal oxidation mechanism was clarified, indicating that the oxygen can permeate into the defects and react with TiCN at high temperatures. In addition, concerning the use of a TiCN coating in high-temperature conditions, the microhardness of the oxidized coatings at different treatment temperatures was also evaluated.

  5. Workplace exposure and release of ultrafine particles during atmospheric plasma spraying in the ceramic industry.

    Science.gov (United States)

    Viana, M; Fonseca, A S; Querol, X; López-Lilao, A; Carpio, P; Salmatonidis, A; Monfort, E

    2017-12-01

    Atmospheric plasma spraying (APS) is a frequently used technique to produce enhanced-property coatings for different materials in the ceramic industry. This work aimed to characterise and quantify the impact of APS on workplace exposure to airborne particles, with a focus on ultrafine particles (UFPs, Particle number, mass concentrations, alveolar lung deposited surface area concentration, and size distributions, in the range 10nm-20μm were simultaneously monitored at the emission source, in the potential worker breathing zone, and in outdoor air. Different input materials (known as feedstock) were tested: (a) micron-sized powders, and (b) suspensions containing submicron- or nano-sized particles. Results evidenced significantly high UFP concentrations (up to 3.3×106/cm3) inside the spraying chamber, which impacted exposure concentrations in the worker area outside the spraying chamber (up to 8.3×105/cm3). Environmental release of UFPs was also detected (3.9×105/cm3, outside the exhaust tube). Engineered nanoparticle (ENP) release to workplace air was also evidenced by TEM microscopy. UFP emissions were detected during the application of both micron-sized powder and suspensions containing submicron- or nano-sized particles, thus suggesting that emissions were process- (and not material-) dependent. An effective risk prevention protocol was implemented, which resulted in a reduction of UFP exposure in the worker area. These findings demonstrate the potential risk of occupational exposure to UFPs during atmospheric plasma spraying, and raise the need for further research on UFP formation mechanisms in high-energy industrial processes. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  6. Application of Atmospheric Plasma-Sprayed Ferrite Layers for Particle Accelerators

    CERN Document Server

    Caspers, F; Federmann, S; Taborelli, M; Schulz, C; Bobzin, K; Wu, J

    2013-01-01

    A common problem in all kinds of cavity-like structures in particle accelerators is the occurrence of RF-resonances. Typically, ferrite plates attached to the walls of such structures as diagnostic devices, kickers or collimators, are used to dampen those undesired modes. However, the heat transfer rate from these plates to the walls is rather limited. Brazing ferrite plates to the walls is not possible in most cases due to the different thermal expansion coefficients. To overcome those limitations, atmospheric plasma spraying techniques have been investigated. Ferrite layers with a thickness from 50 μm to about 300 μm can be deposited on metallic surfaces like stainless steel exhibiting good thermal contact and still reasonable absorption properties. In this paper the technological aspects of plasma deposition are discussed and results of specifically developed RF loss measurement procedures for such thin magnetically lossy layers on metal are presented.

  7. Investigation into the thermal dehydroxylation and decomposition of hydroxylapatite during atmospheric plasma spraying

    OpenAIRE

    Tran, Thi Hong Van

    2009-01-01

    Hydroxylapatite (HA) is a frequently used bioceramic material for replacement of bone matter subjected to low loading conditions, for osseoconductive coatings on implants and for utilisation as a drug carrier. Plasma spraying is widely used to coat hydroxylapatite onto titanium alloys in hip endoprostheses. However, the high temperature of the plasma jet changes the crystallinity and decomposes hydroxylapatite. This affects in turn its bioconductivity. In this study, HA was coated onto Ti6Al4...

  8. Medical equipment bio-capability processes using the atmospheric plasma-sprayed titanium coating

    Science.gov (United States)

    Rezaei, F.; Saviz, S.; Ghoranneviss, M.

    2017-12-01

    Antibacterial surfaces such as titanium coatings are able to have capability in the human body environment. In this study, titanium coatings are deposited on the 316 stainless steel substrates by a handmade plasma spray system. Some mechanical, chemical properties and microstructure of the created titanium layer are determined to evaluate the quality of coating. The XRD, SEM, adhesion tests from cross cut and corrosion test by potentiodynamic are used. During the different stages, some of the parameters are changed in different samples to achieve the best quality in the coating. It is shown that by increasing the spray time, the production of nanoparticles begins. On the other hand, the best layers are created when the spray main gas flow rate has a certain amount.

  9. The detailed analysis of the spray time effects of the aluminium coating using self-generated atmospheric plasma spray system on the microstructure and corrosion behaviour

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    Sh. Khandanjou

    Full Text Available In the present paper our aim is to investigate the effect of the spray time of the aluminium coated layers on the microstructure and corrosion behaviour. For this purpose we use the self-generated atmospheric plasma spray system for coating of aluminium on the carbon steel substrate. The different thicknesses of coating are created. To evaluate this effect we use the several analyses such as X-ray diffraction, scanning electron microscope, Micro hardness analysis by Vickers method, Adhesion strength analysis and electrochemical polarization test. The results are very interesting and show that due to low porosity, thicker layers are more homogeneous. The nanoparticles are observed in the thicker layers. The micro hardness tests show that the thicker layers have the better micro hardness value. Next, the adhesion strength tests illustrate that the highest adhesion strength are for longer spray times. On the other hand, the corrosion resistance behaviour of the coating is investigated by electrochemical polarization test. It is shown that the corrosion resistance increases by increasing the thickness due to low percentage of porosity. Keywords: Plasma spray, Thickness, Aluminium, Micro hardness, Corrosion resistance

  10. The investigation of the microstructure behavior of the spray distances and argon gas flow rates effects on the aluminum coating using self-generated atmospheric plasma spray system

    Science.gov (United States)

    Khandanjou, Sh.; Ghoranneviss, M.; Saviz, Sh.

    2017-09-01

    In the present paper, our aims are the investigation of the effects of the spray parameters of the aluminum-coated layer on the microstructure and mechanical properties. For this purpose, we use the self-generated atmospheric plasma spray system for coating of aluminum on the carbon steel substrate to protect it against corrosion degradation. This system allows us to achieve the best choice for parameters. In this paper, the effects of spray distance and argon flow rate on the characteristics of aluminum coating are investigated. To obtain the results, the analyses are used such as X-ray diffraction, scanning electron microscope, micro hardness of the coating by Vickers method, and adhesion strength behaviors by pull-off test. The results show that the porosity increases with increasing distance. This phenomenon reduces the hardness and adhesion, which is clearly evident in our results. The other important conclusion is that, if the gas flow rate increases, the porosity decreases. It is shown that the best adhesion strength is obtained at the special value of the spraying distance.

  11. Comparison of ZrB2-MoSi2 Composite Coatings Fabricated by Atmospheric and Vacuum Plasma Spray Processes

    Science.gov (United States)

    Niu, Yaran; Wang, Zhong; Zhao, Jun; Zheng, Xuebin; Zeng, Yi; Ding, Chuanxian

    2017-01-01

    In this work, ZrB2-20 vol.% MoSi2 (denoted as ZM) composite coatings were fabricated by atmospheric plasma spray (APS) and vacuum plasma spray (VPS) techniques, respectively. Phase composition and microstructure of the composite coatings were characterized. Their oxidation behaviors and microstructure changes at 1500 °C were comparatively investigated. The results showed that VPS-ZM coating was composed of hexagonal ZrB2, tetragonal and hexagonal MoSi2, while certain amount of ZrO2 existed in APS-ZM coating. The oxide content, surface roughness and porosity of VPS-ZM coating were apparently lower than those of APS-ZM coating. The mass gain of APS-ZM coating was maximum at the beginning (1500 °C, 0 h) and then decreased with the oxidation time extending, while the mass of VPS-ZM coating gradually increased with increasing the oxidation time. The possible reasons for the different oxidation behaviors of the two kinds of coatings were analyzed.

  12. Application of atmospheric solution precursor plasma spray to photocatalytic devices for small and medium industries in developing countries

    Science.gov (United States)

    Kindole, Dickson; Ando, Yasutaka

    2017-01-01

    For development of a functional film deposition process with high deposition rate, as a basic study, TiO2 films were deposited by atmospheric solution precursor plasma spray (ASPPS) process. Ethanol-diluted titanium tetraisobutoxide [TTIB: Ti(OC4H9)4] was used as a feedstock. To achieve a high plasma thermal energy at a low discharge power, N2-dominant Ar/N2 as the plasma working gas was used, for film deposition at various deposition distances. Consequently, photocatalytic TiO2 with a rutile/anatase mixture film structure was deposited evenly in this case. By conducting methylene blue decomposition and wettability tests, photocatalytic properties of the film were confirmed. When a TiO2 film was applied to photocatalytic dye-sensitized solar cells (DSSCs), the cells generated an electromotive force of 0.143V oc, which is close to those of commercial DSSCs. From these results, the ASPPS process was found to have high potential for high rate functional film deposition and was cost effective, making it suitable for developing countries.

  13. The possibilities of atmospheric plasma-spraying application to obtain hydroxyapatite coatings on the stainless steel samples

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    Mihailović Marija D.

    2013-01-01

    Full Text Available For decades, the standard metallic materials for hip implants, besides the 316LVM stainless steel, were titanium- and cobalt/chromium-based alloys. Although bioinert, due to their corrosion resistance, they are not biocompatible. Contemporary surgical implants are not made just of bioinert metal anymore, but with deposited bioactive hydroxyapatite (HAp coating. Hydroxyapatite is chemically identical with the mineral constituent of bones and teeth, what besides its biocompatibility provides bioactivity as well. The HAp limitations are, however, weak tensile strength and low fatigue resistance for long term loadings, if used alone. This is the reason for HAp to be deposited onto the surgical implant, and to enable its bioactivity, what means intergrowth with bones, and therefore the long-lasting and mechanical stable non-cemented prosthesis. This is important predominantly because the need for such prostheses for younger population, and a better life quality. There are several contemporary techniques that have been used for deposition of these coatings onto the metal implant. The possibilities of atmospheric plasma-spraying for obtaining the stable HAp coatings on the 316LVM stainless steel, ordinary used as a standard material for hip implants production are presented in this paper. The coatings of a commercially available hydroxyapatite powder were plasma-sprayed onto the specimens of medical grade 316LVM stainless steel under various operating conditions. The optical microscopy was used for microstructure and porosity characterization, while coating morphology and Ca/P ratio were analyzed using SEM equipped with EDX. Coating microstructure varied from a porous to a glassy structure, depending on operating conditions applied and coating thickness. Coating porosity was determined to be at the lower required limit requested for the bone-coating intergrowth possibility, but nevertheless adhesion measurements showed good results. The Ca/P ratio was

  14. Corrosion performance of atmospheric plasma sprayed alumina coatings on AZ31B magnesium alloy under immersion environment

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    D. Thirumalaikumarasamy

    2014-12-01

    Full Text Available Plasma sprayed ceramic coatings are successfully used in many industrial applications, where high wear and corrosion resistance with thermal insulation are required. The alumina powders were plasma sprayed on AZ31B magnesium alloy with three different plasma spraying parameters. In the present work, the influence of plasma spray parameters on the corrosion behavior of the coatings was investigated. The corrosion behavior of the coated samples was evaluated by immersion corrosion test in 3.5 wt% NaCl solution. Empirical relationship was established to predict the corrosion rate of plasma sprayed alumina coatings by incorporating process parameters. The experiments were conducted based on a three factor, five-level, central composite rotatable design matrix. The developed relationship can be effectively used to predict the corrosion rate of alumina coatings at 95% confidence level. The results indicate that the input power has the greatest influence on corrosion rate, followed by stand-off distance and powder feed rate.

  15. Electrical Properties of Atmospheric Plasma-Sprayed La10(SiO4)6O3 Electrolyte Coatings

    Science.gov (United States)

    Gao, Wei; Li, Wen-Ya; Liao, Han-Lin; Coddet, Christian

    2011-06-01

    In this present work, La10(SiO4)6O3 as a promising electrolyte candidate for intermediate temperature solid oxide fuel cells (IT-SOFCs) has been synthesized and its electrical property was investigated as a function of temperature. In order to improve the density and oxide ion conductivity of La10(SiO4)6O3, the feedstock powder was prepared by sintering the oxide mixture powders at proper sintering temperatures and times. The hexagonal apatite-type ceramic coatings with a typical composition of La10(SiO4)6O3 were deposited by atmospheric plasma spraying (APS) with different hydrogen flow rates. With increasing hydrogen flow rate oxide ion conductivity successively decreases. The highest ionic conductivity of the dense composite electrolyte coatings reaches a value of 2.4 mS/cm at 900 °C in air, which is comparable to other apatite-type lanthanum silicate (ATLS) conductors.

  16. The role of amorphous phase content on the electrical properties of atmospheric plasma sprayed (Ba,Sr)TiO3 coatings

    Czech Academy of Sciences Publication Activity Database

    Kotlan, Jiří; Seshadri, R.C.; Sampath, S.; Ctibor, Pavel

    2016-01-01

    Roč. 42, č. 9 (2016), s. 11010-11014 ISSN 0272-8842 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389021 Keywords : X-ray methods * Electrical properties * Perovskites * Atmospheric Plasma Spray Subject RIV: JH - Ceramics , Fire-Resistant Materials and Glass Impact factor: 2.986, year: 2016 http://www.sciencedirect.com/science/article/pii/S0272884216303856

  17. Influence of atmospheric plasma spray parameters on YSZ coatings obtained from micro and nano structured feedstocks; Influencia de los parametros de proyeccion por plasma atmosferico en recubrimientos de YSZ obtenidos a partir de polvos micro y nanoestructurados

    Energy Technology Data Exchange (ETDEWEB)

    Carpio, P.; Bannier, E.; Borrell, A.; Salvador, M. d.; Sanchez, E.

    2014-07-01

    In the present work, the influence of atmospheric plasma spray (APS) parameters on the deposition of two commercial YSZ feedstocks, one conventional and one non-conductor's, has been studied. First the study focused on how the variability of the different parameters affects the particle behaviour during spraying. For this purpose, a sensor which enables to measure the particle temperature and velocity inside the plasma was used. Once the spraying parameters influence was known, both powders were deposited by APS onto stainless steel substrates modifying the higher influencing parameters. These coatings have been characterised and the influence of the particle behaviour on the coating microstructure and properties has been analysed. This work concludes the spraying parameters variation affects on the particle velocity and temperature inside the plasma plume and this behaviour influences, in turn but in a different way, on the final coating characteristics when using different powders (micro- and nano structured). (Author)

  18. Self-healing atmospheric plasma sprayed Mn1.0Co1.9Fe0.1O4 protective interconnector coatings for solid oxide fuel cells

    Science.gov (United States)

    Grünwald, Nikolas; Sebold, Doris; Sohn, Yoo Jung; Menzler, Norbert Heribert; Vaßen, Robert

    2017-09-01

    Dense coatings on metallic interconnectors are necessary to suppress chromium poisoning of SOFC cathodes. Atmospherically plasma sprayed (APS) Mn1.0Co1.9Fe0.1O4 (MCF) protective layers demonstrated reduced chromium related degradation in laboratory and stack tests. Previous analyses revealed strong microstructural changes comparing the coating's as-sprayed and operated condition. This work concentrates on the layer-densification and crack-healing observed by annealing APS-MCF in air, which simulates the cathode operation conditions. The effect is described by a volume expansion induced by a phase transformation. Reducing conditions during the spray process lead to a deposition of the MCF in a metastable rock salt configuration. Annealing in air activates diffusion processes for a phase transformation to the low temperature stable spinel phase (T gas route is blocked and further oxidation continues over solid state diffusion. The self-healing abilities of metastable APS coatings could be interesting for other applications.

  19. Effect of helium plasma gas flow rate on the properties of WC-12 wt.%Co coatings sprayed by atmospheric plasma

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    Mihailo R. Mrdak

    2014-06-01

    Full Text Available The cermet coatings of WC-12wt.%Co are extensively used to improve the wear resistance of a wide range of technical components. This paper analyses the influence of the plasma gas flow of helium on the microstructure and mechanical properties of WC-12wt.%Co coatings deposited by plasma spraying at atmospheric pressure (APS. In order to obtain homogeneous and denser coatings, three different flows of He ( 8 l/min., 16 l/min. and 32 l/min were used in the research. With the application of He, coatings achieved higher values of hardness due to less degradation of the primary WC carbides. The main goal was to deposit dense and homogeneous layers of WC-12wt.%Co coatings with improved wear resistance for different applications. The test results of the microstructure of the layers were evaluated under a light microscope. The analysis of the microstructure and the mechanical properties of the deposited layers was made in accordance with the standard of Pratt-Whitney. The morphology of the powder particles and the microstructure of the best coating was examined on the SEM (scanning electron microscope. The evaluation of the mechanical properties of the layers was done by applying the HV0.3 method for microhardness testing and by applying tensile testing to test the bond strength. The research has shown that the flow of He plasma gas significantly affects the microstructure, the mechanical properties and the structure of WC-12 wt.%Co coatings.

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

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    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.

  1. Atmospheric-pressure plasma technology

    Science.gov (United States)

    Kogelschatz, U.

    2004-12-01

    Major industrial plasma processes operating close to atmospheric pressure are discussed. Applications of thermal plasmas include electric arc furnaces and plasma torches for generation of powders, for spraying refractory materials, for cutting and welding and for destruction of hazardous waste. Other applications include miniature circuit breakers and electrical discharge machining. Non-equilibrium cold plasmas at atmospheric pressure are obtained in corona discharges used in electrostatic precipitators and in dielectric-barrier discharges used for generation of ozone, for pollution control and for surface treatment. More recent applications include UV excimer lamps, mercury-free fluorescent lamps and flat plasma displays.

  2. Establishing empirical relationships to predict porosity level and corrosion rate of atmospheric plasma-sprayed alumina coatings on AZ31B magnesium alloy

    Directory of Open Access Journals (Sweden)

    D. Thirumalaikumarasamy

    2014-06-01

    Full Text Available Plasma sprayed ceramic coatings are successfully used in many industrial applications, where high wear and corrosion resistance with thermal insulation are required. In this work, empirical relationships were developed to predict the porosity and corrosion rate of alumina coatings by incorporating independently controllable atmospheric plasma spray operational parameters (input power, stand-off distance and powder feed rate using response surface methodology (RSM. A central composite rotatable design with three factors and five levels was chosen to minimize the number of experimental conditions. Within the scope of the design space, the input power and the stand-off distance appeared to be the most significant two parameters affecting the responses among the three investigated process parameters. A linear regression relationship was also established between porosity and corrosion rate of the alumina coatings. Further, sensitivity analysis was carried out and compared with the relative impact of three process parameters on porosity level and corrosion rate to verify the measurement errors on the values of the uncertainty in estimated parameters.

  3. Advanced Nanoscale Coatings with Plasma Spray

    National Research Council Canada - National Science Library

    Atteridge, David

    2000-01-01

    .... A secondary research charter developed as this program proceeded was the assessment of the feasibility of using cored wire filled with WE-Co powder as a feed-stock for both plasma spray and twin-wire-arc spray (TWAS...

  4. Optimization of cylinder liner plasma spraying mode

    Science.gov (United States)

    Timokhova, O. M.; Burmistrova, O. N.; Sirina, E. A.

    2017-10-01

    At present one of the most promising methods to remanufacture worn-out machine parts is plasma spraying. The paper describes the selection of the optimum plasma spraying technique to coat the worn-out wall surface of the diesel engine cylinder liners. All the data have been MathCad processed and the regression models equivalent to the algoristic-type model of plasma spraying have been developed. The experiments have resulted in achieving the optimization parameters, the mean value of which is presented in the paper. The given plasma spraying mode allows one not only to remanufacture the worn-out wall surface of the diesel engine cylinder liners but also to obtain the best coating properties.

  5. Properties of Plasma and HVOF Sprayed Coatings

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    Wojciech Żórawski

    2012-11-01

    Full Text Available The work compares the properties of plasma and HVOF thermally sprayed coatings obtained by blending the NiCrBSi and Fe2O3 powders. The deposition was performed by means of the Plancer PN-120 and the Diamond Jet guns for plasma spraying and HVOF spraying respectively. The SEM (EDS method was employed to study the microstructure of the produced coatings. Although the blended powders differ in particle size, shape, and distribution, it is possible to obtain composite coatings with an NiCrBSi matrix containing iron oxides. Except for a different microstructure, plasma and HVOF coatings have a different phase composition, which was examined using the Bruker D-8 Advance diffractometer. Studies of the coatings wear and scuffing resistance showed that an optimal content of Fe2O3 is about 26 % for plasma sprayed coatings and 22.5 % for HVOF deposited coatings.

  6. Manufacturing of Composite Coatings by Atmospheric Plasma Spraying Using Different Feed-Stock Materials as YSZ and MoSi2

    Science.gov (United States)

    Koch, D.; Mauer, G.; Vaßen, R.

    2017-04-01

    Yttria-stabilized zirconia (YSZ) is the state-of-the-art material for the top coat of thermal barrier coatings. To increase the efficiency and lifetime of gas turbines, the integration of MoSi2 as a healing material was proposed. A new method of manufacture was explored in order to enable the spraying of a homogeneous mixed layer of YSZ and MoSi2. As the chemical and physical properties of these powders are very different, they require contrasting process conditions. Due to the evaporation of Si from MoSi2 at spraying conditions suitable for YSZ, more moderate conditions and a shorter time of flight are required for depositing MoSi2. At the same time, the spraying conditions still need to be sufficient for melting the YSZ particles in order to produce a coating. To obtain a homogeneous mixture, both conditions can be matched using an injection system that allows powder injection at two different locations of the plasma jet. Two-color pyrometry during flight (DPV-2000, Tecnar) was used to monitor the actual particle temperature. By optimizing the injection point for the MoSi2, a mixed coating was obtained without decomposition of the MoSi2, which has been analyzed by means of XRD and SEM.

  7. Rugged Preheaters For Vacuum Plasma Spraying

    Science.gov (United States)

    Woodford, William H.; Mckechnie, Timothy N.; Sander, Lewis D.; Power, Christopher A.; Sander, Heather L.; Nguyen, Dalton D.

    1994-01-01

    Electric preheater units built to ensure large workpieces to be coated with metals by vacuum plasma spraying heated uniformly to requisite high temperatures by time plasma torch arrives. Units similar to electrical-resistance ribbon heaters in toasters and in some small portable electric "space" heaters. Nichrome resistance-heating ribbons wrapped around ceramic insulating spools on rings and on plates. Round workpiece placed in middle of ring preheater. Plate preheaters stacked as needed near workpiece.

  8. Study of Multi-Function Micro-Plasma Spraying Technology

    Science.gov (United States)

    Wang, Liuying; Wang, Hangong; Hua, Shaochun; Cao, Xiaoping

    2007-02-01

    A multi-functional micro-arc plasma spraying system was developed according to aerodynamics and plasma spray theory. The soft switch IGBT (Insulated Gate Bipolar Transistor) invert technique, micro-computer control technique, convergent-divergent nozzle structure and axial powder feeding techniques have been adopted in the design of the micro-arc plasma spraying system. It is not only characterized by a small volume, a light weight, highly accurate control, high deposition efficiency and high reliability, but also has multi-functions in plasma spraying, welding and quenching. The experimental results showed that the system can produce a supersonic flame at a low power, spray Al2O3 particles at an average speed up to 430 m/s, and make nanostructured AT13 coatings with an average bonding strength of 42.7 MPa. Compared to conventional 9M plasma spraying with a higher power, the coatings with almost the same properties as those by conventional plasma spray can be deposited by multi-functional micro-arc plasma spraying with a lower power plasma arc due to an improved power supply design, spray gun structure and powder feeding method. Moreover, this system is suitable for working with thin parts and undertaking on site repairs, and as a result, the application of plasma spraying will be greatly extended.

  9. Research of Plasma Spraying Process on Aluminum-Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    Patricija Kavaliauskaitė

    2016-04-01

    Full Text Available The article examines plasma sprayed 95Ni-5Al coatings on alu-minum-magnesium (Mg ≈ 2,6‒3,6 % alloy substrate. Alumi-num-magnesium samples prior spraying were prepared with mechanical treatment (blasting with Al2O3. 95Ni-5Al coatings on aluminum-magnesium alloys were sprayed with different parameters of process and coating‘s thickness, porosity, micro-hardness and microstructure were evaluated. Also numerical simulations in electric and magnetic phenomena of plasma spray-ing were carried out.

  10. Numerical Study of Suspension Plasma Spraying

    CERN Document Server

    Farrokhpanah, Amirsaman; Mostaghimi, Javad

    2016-01-01

    A numerical study of suspension plasma spraying (SPS) is presented in the current work. The liquid suspension jet is replaced with a train of droplets containing the suspension particles injected into the plasma flow. Atomization, evaporation, and melting of different components are considered for particles as they travel towards the substrate. Effect of different parameters on particle conditions during flight and upon impact on the substrate are investigated. Initially, influence of the torch operating conditions such as inlet flow rate and power are studied. Additionally, effect of injector parameters like injection location, flow rate, and angle are examined. The model used in current study takes high temperature gradients and non-continuum effects into account. Moreover, the important effect of change in physical properties of suspension droplets as a result of evaporation is included in the model. These mainly include variations in heat transfer properties and viscosity. Utilizing this improved model, s...

  11. Plasma sprayed coatings for RF wave absorption

    Science.gov (United States)

    Nanobashvili, S.; Matějíček, J.; Žáček, F.; Stőckel, J.; Chráska, P.; Brožek, V.

    2002-12-01

    High requirements for fusion reactor materials and for experimental fusion devices have led within the fusion community to the development and testing of various coatings of the surfaces of in-vessel components and biological shields for microwave heating systems. Based on contacts with ITER, W7X and the Spanish Stellarator TJ-II, IPP Prague has initiated a development, production and test program on various low- Z materials. This paper reports on the production, development and properties of B 4C, Si and Al 2O 3 coatings sprayed by water stabilized plasma. Main focus is on their radio frequency wave reflection properties. Further characterization includes the coating structure by microscopy, phase composition by X-ray diffraction and oxygen content measurement by atomic absorption spectroscopy. The results are discussed with respect to processing conditions as well as potential application.

  12. Plasma sprayed coatings for RF wave absorption

    Energy Technology Data Exchange (ETDEWEB)

    Nanobashvili, S.; Matejicek, J. E-mail: jmatejic@ipp.cas.cz; Zacek, F.; Stockel, J.; Chraska, P.; Brozek, V

    2002-12-01

    High requirements for fusion reactor materials and for experimental fusion devices have led within the fusion community to the development and testing of various coatings of the surfaces of in-vessel components and biological shields for microwave heating systems. Based on contacts with ITER, W7X and the Spanish Stellarator TJ-II, IPP Prague has initiated a development, production and test program on various low-Z materials. This paper reports on the production, development and properties of B{sub 4}C, Si and Al{sub 2}O{sub 3} coatings sprayed by water stabilized plasma. Main focus is on their radio frequency wave reflection properties. Further characterization includes the coating structure by microscopy, phase composition by X-ray diffraction and oxygen content measurement by atomic absorption spectroscopy. The results are discussed with respect to processing conditions as well as potential application.

  13. Numerical Study of Suspension Plasma Spraying

    Science.gov (United States)

    Farrokhpanah, Amirsaman; Coyle, Thomas W.; Mostaghimi, Javad

    2017-01-01

    A numerical study of suspension plasma spraying is presented in the current work. The liquid suspension jet is replaced with a train of droplets containing the suspension particles injected into the plasma flow. Atomization, evaporation, and melting of different components are considered for droplets and particles as they travel toward the substrate. Effect of different parameters on particle conditions during flight and upon impact on the substrate is investigated. Initially, influence of the torch operating conditions such as inlet flow rate and power is studied. Additionally, effect of injector parameters like injection location, flow rate, and angle is examined. The model used in the current study takes high-temperature gradients and non-continuum effects into account. Moreover, the important effect of change in physical properties of suspension droplets as a result of evaporation is included in the model. These mainly include variations in heat transfer properties and viscosity. Utilizing this improved model, several test cases have been considered to better evaluate the effect of different parameters on the quality of particles during flight and upon impact on the substrate.

  14. Development of YSZ Thermal Barrier Coatings Using Axial Suspension Plasma Spraying

    Directory of Open Access Journals (Sweden)

    Dapeng Zhou

    2017-08-01

    Full Text Available The axial injection of the suspension in the atmospheric plasma spraying process (here called axial suspension plasma spraying is an attractive and advanced thermal spraying technology especially for the deposition of thermal barrier coatings (TBCs. It enables the growth of columnar-like structures and, hence, combines advantages of electron beam-physical vapor deposition (EB-PVD technology with the considerably cheaper atmospheric plasma spraying (APS. In the first part of this study, the effects of spraying conditions on the microstructure of yttria partially-stabilized zirconia (YSZ top coats and the deposition efficiency were investigated. YSZ coatings deposited on as-sprayed bond coats with 5 wt % solid content suspension appeared to have nicely-developed columnar structures. Based on the preliminary results, the nicely developed columnar coatings with variations of the stand-off distances and yttria content were subjected to thermal cycling tests in a gas burner rig. In these tests, all columnar structured TBCs showed relatively short lifetimes compared with porous APS coatings. Indentation measurements for Young’s modulus and fracture toughness on the columns of the SPS coatings indicated a correlation between mechanical properties and lifetime for the SPS samples. A simplified model is presented which correlates mechanical properties and lifetime of SPS coatings.

  15. Superhydrophobic Ceramic Coatings by Solution Precursor Plasma Spray

    Science.gov (United States)

    Cai, Yuxuan; Coyle, Thomas W.; Azimi, Gisele; Mostaghimi, Javad

    2016-04-01

    This work presents a novel coating technique to manufacture ceramic superhydrophobic coatings rapidly and economically. A rare earth oxide (REO) was selected as the coating material due to its hydrophobic nature, chemical inertness, high temperature stability, and good mechanical properties, and deposited on stainless steel substrates by solution precursor plasma spray (SPPS). The effects of various spraying conditions including standoff distance, torch power, number of torch passes, types of solvent and plasma velocity were investigated. The as-sprayed coating demonstrated a hierarchically structured surface topography, which closely resembles superhydrophobic surfaces found in nature. The water contact angle on the SPPS superhydrophobic coating was up to 65% higher than on smooth REO surfaces.

  16. Comparison of the characteristics of HVOF and plasma thermal spray

    Energy Technology Data Exchange (ETDEWEB)

    Fincke, J.R.; Swank, W.D.; Haggard, D.C. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1994-12-31

    In spraying oxygen sensitive materials, such as WC:Co it is often observed that the carbide fraction present in the deposit is significantly less than in the original particles. This lowers the hardness of the coating, resulting in inferior wear resistance. The cause is the in-flight, high temperature decomposition of carbides by reaction with entrained oxygen. The degree of decomposition is determined by a combination of particle temperature, residence time and entrainment characteristics of the jet. The fundamental differences between HVOF and plasma thermal spray are examined in this context. Even though the HVOF process may actually subject a particle to greater oxygen exposure than plasma spraying, the lower particle temperatures experienced lead to coatings which exhibit less carbide loss than plasma sprayed coatings fabricated in air.

  17. Plasma spraying of bioactive glass-ceramics containing bovine bone

    Directory of Open Access Journals (Sweden)

    Annamária Dobrádi

    2017-06-01

    Full Text Available Natural bone derived glass-ceramics are promising biomaterials for implants. However, due to their price and weak mechanical properties they are preferably applied as coatings on load bearing implants. This paper describes result obtained by plasma spraying of bioactive glass-ceramics containing natural bone onto selected implant materials, such as stainless steel, alumina, and titanium alloy. Adhesion of plasma sprayed coating was tested by computed X-ray tomography and SEM of cross sections. The results showed defect free interface between the coating and substrate, without cracks or gaps. Dissolution rate of the coating in simulated body fluid (SBF was readily controlled by the bone additives (phase composition, as well as microstructure. The SBF treatment of the plasma sprayed coating did not influence the boundary between the coating and substrate.

  18. The influence of substrate temperature and spraying distance on the properties of plasma sprayed tungsten and steel coatings deposited in a shrouding chamber

    Czech Academy of Sciences Publication Activity Database

    Matějíček, Jiří; Vilémová, Monika; Nevrlá, Barbara; Kocmanová, Lenka; Veverka, Jakub; Halasová, Martina; Hadraba, Hynek

    2017-01-01

    Roč. 318, May (2017), s. 217-223 ISSN 0257-8972. [International Meeting on Thermal Spraying (RIPT)/7./. Limoges, 09.12.2015-11.12.2015] R&D Projects: GA ČR GB14-36566G EU Projects: European Commission(XE) 633053 - EUROfusion Institutional support: RVO:61389021 ; RVO:68081723 Keywords : Tungsten * Steel * Atmospheric plasma spraying * Shrouding * Substrate temperature * Fusion reactor materials * Plasma facing components Subject RIV: JK - Corrosion ; Surface Treatment of Materials; JK - Corrosion ; Surface Treatment of Materials (UFM-A) Impact factor: 2.589, year: 2016 http://www.sciencedirect.com/science/article/pii/S0257897216310520

  19. Measurement of the non-thermal properties of a low pressure spraying plasma by electric and spectroscopic methods

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Yong Ho

    2003-02-15

    For the case of an atmospheric plasma, the local thermodynamic equilibrium (LTE) model can be applied to plasmas at a nozzle entrance and to those on the axis of the plasma flame, but it is not easy to justify applying the LTE model to off-center plasma and to a low-pressure spraying plasma. Although the energy distribution of the electrons is assumed to be Maxwellian for the most of spraying plasmas, the non-Maxwellian distribution is possible for the case of low-pressure spaying plasma and edge plasma of atmospheric spraying plasma. In this work, the non-Maxwellian distribution of electrons was measured by using an electric probe installed on the fast scanning probe system, and non-LTE effects were measured by using the optical emission spectroscopy system. Distribution of the electrons of a low-pressure spraying plasma is observed not as Maxwellian but as bi-Maxwellian by the measurement of the single probe. Bi-Maxwellian distribution appears in the edge of a low pressure spraying plasma and seems to be due to the reduction of the collisonality by the drastic variation of the plasma density. Non-LTE characteristics of a low-pressure spraying plasma can be deuced from the measured results of the optical emission spectroscopy and is analyzed by the collisional radiative equilibrium (CRE) model, where the Maxwellian and the non-Maxwellian distributions are assumed for comparison. For the electron temperature, the results from optical emission spectroscopy were similar to the results from the single probe (3{approx}5 % in error)

  20. Metallurgy and properties of plasma spray formed materials

    Science.gov (United States)

    Mckechnie, T. N.; Liaw, Y. K.; Zimmerman, F. R.; Poorman, R. M.

    1992-01-01

    Understanding the fundamental metallurgy of vacuum plasma spray formed materials is the key to enhancing and developing full material properties. Investigations have shown that the microstructure of plasma sprayed materials must evolve from a powder splat morphology to a recrystallized grain structure to assure high strength and ductility. A fully, or near fully, dense material that exhibits a powder splat morphology will perform as a brittle material compared to a recrystallized grain structure for the same amount of porosity. Metallurgy and material properties of nickel, iron, and copper base alloys will be presented and correlated to microstructure.

  1. Plasma sprayed and electrospark deposited zirconium metal diffusion barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Hollis, Kendall J [Los Alamos National Laboratory; Pena, Maria I [Los Alamos National Laboratory

    2010-01-01

    Zirconium metal coatings applied by plasma spraying and electrospark deposition (ESD) have been investigated for use as diffusion barrier coatings on low enrichment uranium fuel for research nuclear reactors. The coatings have been applied to both stainless steel as a surrogate and to simulated nuclear fuel uranium-molybdenum alloy substrates. Deposition parameter development accompanied by coating characterization has been performed. The structure of the plasma sprayed coating was shown to vary with transferred arc current during deposition. The structure of ESD coatings was shown to vary with the capacitance of the deposition equipment.

  2. Tungsten oxide coatings deposited by plasma spray using powder and solution precursor for detection of nitrogen dioxide gas

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chao, E-mail: zhangc@yzu.edu.cn [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China); Wang, Jie [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China); Geng, Xin [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China); College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China)

    2016-05-25

    Increasing attention has been paid on preparation methods for resistive-type gas sensors based on semiconductor metal oxides. In this work, tungsten oxide (WO{sub 3}) coatings were prepared on alumina substrates and used as gas sensitive layers. The coatings were deposited by atmospheric plasma spray using powder, solution precursor, or a combination of both. Tungsten oxide powder through a powder port and ammonium tungstate aqueous solution through a liquid port were injected into plasma stream respectively or together to deposit WO{sub 3} coatings. Phase structures in the coatings were characterized by X-ray diffraction analyzer. The field-emission scanning electron microscopy images confirmed that the coatings were in microstructure, nanostructure or micro-nanostructure. The sensing properties of the sensors based on the coatings exposed to 1 ppm nitrogen dioxide gas were characterized in a home-made instrument. Sensing properties of the coatings were compared and discussed. The influences of gas humidity and working temperature on the sensor responses were further studied. - Highlights: • Porous gas sensitive coatings were deposited by plasma spray using powder and solution precursor. • Crystallized WO{sub 3} were obtained through hybrid plasma spray plus a pre-conditioned step. • Plasma power had an important influence on coating microstructure. • The particle size of atmospheric plasma-sprayed microstructured coating was stable. • Solution precursor plasma-sprayed WO{sub 3} coatings had nanostructure and showed good responses to 1 ppm NO{sub 2}.

  3. Simulation of the Particle Melting Degree in Air Plasma Spraying

    Science.gov (United States)

    Bobzin, K.; Öte, M.; Knoch, M. A.; Alkhasli, I.; Reisgen, U.; Mokrov, O.; Lisnyi, O.

    2017-04-01

    Plasma spraying is a coating process which is widely used for the application of thermal barrier coatings. High plasma jet temperatures allow the processing of ceramic material particles which characteristically exhibit low thermal conductivities. This, in turn, produces high temperature gradients inside the particles and vaporization on the particles’ surface during their dwell time in the plasma jet. Thus, a single particle in the plasma-jet can exhibit 3 states of matter simultaneously: solid in the core, molten exterior and gaseous on the surface. The temperature distribution inside the particles is the foremost factor which influences the particles’ behavior during their impact on the substrate surface. Experimental investigations can provide only the surface temperature of the particles, which is not a good indicator of the melting degree for ceramic particles due to the high temperature gradients. This study focuses on the determination of the temperature distributions inside the particles, during their flight in the plasma and the free jet, with the help of numerical simulations. For this purpose, a numerical model of the plasma spraying process that describes the plasma and the free jet loaded with sprayed particles is presented. The model includes three sub-models; a plasma torch sub-model, a particle-laden free jet sub-model and a powder particles sub-model. The first sub-model calculates the temperature and velocity fields of the plasma inside the plasma torch, the second sub-model the kinetics of temperature and velocity fields of the turbulent free jet generated by the plasma torch. This information is used in the third sub-model to calculate the kinetics of temperature distribution within the particles, their melting degree and mass losses due to evaporation. The third sub-model also calculates heat and mechanical impulse loses due to the particle-plasma interaction, which in turn is coupled with the free jet sub-model.

  4. Dielectric Strontium Zirconate Sprayed by a Plasma Torch.

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Sedláček, J.; Janata, Marek

    2017-01-01

    Roč. 10, č. 4 (2017), s. 226-230 ISSN 2008-2134 Institutional support: RVO:61389021 Keywords : Plasma spraying * Electrical properties * Strontium Zirconate * Insulators Subject RIV: JH - Ceramics , Fire-Resistant Materials and Glass www.pccc.icrc.ac.ir/Articles/18/1/18/1010/

  5. Plasma sprayed alumina coatings for radiation detector development

    Indian Academy of Sciences (India)

    Abstract. Conventional design of radiation detectors uses sintered ceramic insulating modules. The major drawback of these ceramic components is their inherent brittleness. Ion chambers, in which these ceramic spacers are replaced by metallic components with plasma spray coated alumina, have been developed in our ...

  6. In vitro corrosion investigations of plasma-sprayed hydroxyapatite ...

    Indian Academy of Sciences (India)

    The present paper discusses various issues associated with biological corrosion of uncoated and plasma-sprayed hydroxyapatite (HA)-coated 316L SS and studies the effect of contents of calcium phosphate (CaP) on corrosion behaviour of hydroxyapatite (HA) coatings in simulated body fluid (Ringer's solution).

  7. In vitro corrosion investigations of plasma-sprayed hydroxyapatite ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. The present paper discusses various issues associated with biological corrosion of uncoated and plasma-sprayed hydroxyapatite (HA)-coated 316L SS and studies the effect of contents of calcium phosphate. (CaP) on corrosion behaviour of hydroxyapatite (HA) coatings in simulated body fluid (Ringer's solution).

  8. STUDY ON HYDROXYAPATITE COATING ON BIOMATERIALS BY PLASMA SPRAY METHOD

    OpenAIRE

    Dr. Hanumantharaju H. G; Dr. H.K.Shivanand; Prashanth K. P; K. Suresh Kumar; S. P. Jagadish

    2012-01-01

    In plasma spray coating process the hydroxyapatite powder particles are melted in a high temperature plasma flame and propelled towards the substrate material thus forming a coating. The thin hydroxyapatitecoatings have shown better adhesion to substrates and are more stable in the biological environment because they have more uniform structure and composition. Samples are tested for Scanning Electron Microscopy analysis, to find the uniform coating and bonding strength. From the XRD analysis...

  9. Calcium titanate (CaTiO{sub 3}) dielectrics prepared by plasma spray and post-deposition thermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Ctibor, Pavel [Materials Engineering Department, Institute of Plasma Physics ASCR, v.v.i., Za Slovankou 3, Prague 8 (Czech Republic); Kotlan, Jiri, E-mail: kotlan@ipp.cas.cz [Materials Engineering Department, Institute of Plasma Physics ASCR, v.v.i., Za Slovankou 3, Prague 8 (Czech Republic); Department of Electrotechnology, Faculty of Electrical Engineering, Czech Technical University in Prague, Technicka 2, Prague 6 (Czech Republic); Pala, Zdenek [Materials Engineering Department, Institute of Plasma Physics ASCR, v.v.i., Za Slovankou 3, Prague 8 (Czech Republic); Sedlacek, Josef [Department of Electrotechnology, Faculty of Electrical Engineering, Czech Technical University in Prague, Technicka 2, Prague 6 (Czech Republic); Hajkova, Zuzana; Grygar, Tomas Matys [Institute of Inorganic Chemistry ASCR, v.v.i., Husinec-Rez 1001, Rez (Czech Republic)

    2015-12-15

    Highlights: • Calcium titanate was sprayed by two different plasma spray systems. • Significant improvement of dielectric properties after annealing was observed. • Calcium titanate self-supporting parts can be fabricated by plasma spraying. - Abstract: This paper studies calcium titanate (CaTiO{sub 3}) dielectrics prepared by plasma spray technology. A water stabilized plasma gun (WSP) as well as a widely used gas stabilized plasma gun (GSP) were employed in this study to deposit three sample sets at different spray conditions. Prepared specimens were annealed in air at atmospheric pressure for 2 h at various temperatures from 530 to 1170 °C. X-ray diffraction (XRD), Raman spectroscopy and porosity measurements were used for sample characterization. Dielectric spectroscopy was applied to obtain relative permittivity, conductivity and loss factor frequency dependence. Band gap energy was estimated from reflectance measurements. The work is focused on the explanation of changes in microstructure and properties of a plasma sprayed deposit after thermal annealing. Obtained results show significant improvement of dielectric properties after thermal annealing.

  10. Electroform/Plasma-Spray Laminates for X-Ray Optics

    Science.gov (United States)

    Ulmer, Melville P.; Graham, Michael; Vaynman, Semyon

    2007-01-01

    Electroform/plasma-spray laminates have shown promise as lightweight, strong, low-thermal-expansion components for xray optics. The basic idea is to exploit both (1) the well-established art of fabrication of optical components by replication and (2) plasma spraying as a means of reinforcing a thin replica optic with one or more backing layer(s) having tailorable thermomechanical properties. In x-ray optics as in other applications, replication reduces the time and cost of fabrication because grinding and polishing can be limited to a few thick masters, from which many lightweight replicas can thereafter be made. The first step in the fabrication of a component of the type in question is to make a replica optic by electroforming a thin layer of nickel on a master. Through proper control of the electroforming process conditions, it is possible to minimize residual stress and, hence, to minimize distortion in the replica. Next, a powder comprising ceramic particles coated with a metal compatible with the electroformed nickel is plasma-sprayed onto the backside of the nickel replica. Then through several repetitions and variations of the preceding steps or perhaps a small compressive stress, alternating layers of electroformed nickel and plasma-sprayed metal-coated ceramic powder are deposited. The thicknesses of the layers and the composition of the metal-coated ceramic powder are chosen to optimize the strength, areal mass density, and toughness of the finished component. An important benefit of using both electroforming and plasma spraying is the possibility of balancing stresses to a minimum level, which could be zero or perhaps a small net compressive stress designed to enhance the function of the component in its intended application.

  11. Deposition of titanium nitride and hydroxyapatite-based biocompatible composite by reactive plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Rosu, Radu Alexandru [University ' Politehnica' of Timisoara, Faculty of Mechanical Engineering, 1 Mihai Viteazul Blv., 300222 Timisoara (Romania); National Research and Development Institute for Welding and Material Testing Timisoara, 30 Mihai Viteazul Blv., 300222 Timisoara (Romania); Serban, Viorel-Aurel [University ' Politehnica' of Timisoara, Faculty of Mechanical Engineering, 1 Mihai Viteazul Blv., 300222 Timisoara (Romania); Bucur, Alexandra Ioana, E-mail: alexandra.i.bucur@gmail.com [National Institute for Research and Development in Electrochemistry and Condensed Matter Timisoara, Analysis and Characterization Dept, 1 P Andronescu Street, 300224 Timisoara (Romania); Dragos, Utu [University ' Politehnica' of Timisoara, Faculty of Mechanical Engineering, 1 Mihai Viteazul Blv., 300222 Timisoara (Romania)

    2012-02-01

    Titanium nitride is a bioceramic material successfully used for covering medical implants due to the high hardness meaning good wear resistance. Hydroxyapatite is a bioactive ceramic that contributes to the restoration of bone tissue, which together with titanium nitride may contribute to obtaining a superior composite in terms of mechanical and bone tissue interaction matters. The paper presents the experimental results in obtaining composite layers of titanium nitride and hydroxyapatite by reactive plasma spraying in ambient atmosphere. X-ray diffraction analysis shows that in both cases of powders mixtures used (10% HA + 90% Ti; 25% HA + 75% Ti), hydroxyapatite decomposition occurred; in variant 1 the decomposition is higher compared with the second variant. Microstructure of the deposited layers was investigated using scanning electron microscope, the surfaces presenting a lamellar morphology without defects such as cracks or microcracks. Surface roughness values obtained vary as function of the spraying distance, presenting higher values at lower thermal spraying distances.

  12. Characterization of flame-sprayed and plasma-sprayed pure metallic and alloyed coatings

    Energy Technology Data Exchange (ETDEWEB)

    Iordanova, I. [Sofia Univ. (Bulgaria). Dept. of Solid State Phys.; Forcey, K.S. [CEC, Joint Research Centre, Ispra Site, 21020 Ispra (Vatican City State, Holy See) (Italy); Gergov, B. [Sofia Univ. (Bulgaria). Dept. of Solid State Phys.; Bojinov, V. [Department of Inorganic Chemical Technology, The University of Sofia, Blvd. J. Bouchier 1, 1126 Sofia (Bulgaria)

    1995-05-01

    The composition, structure and properties of thermally sprayed coatings were investigated by a number of methods, including X-ray diffraction, X-ray spectroscopy and scanning electron microscopy. The Vickers hardness and porosity were also investigated. The coatings were plasma-sprayed pure molybdenum, and flame-sprayed copper and nickel alloys. It was found that the alloyed coatings had a different chemical composition than the powders they had been produced from. In addition, all the coatings exhibited a fibre texture which complicated the X-ray method for estimation of residual stresses. However, for the pure molybdenum coating, it was possible to evaluate this parameter, taking into account the effects of the measured porosity and crystallographical anisotropy on the Young`s modulus and Poisson`s ratio. ((orig.))

  13. Microwave diagnostics of atmospheric plasmas

    Science.gov (United States)

    Scott, David

    Plasma treatment of biological tissues has tremendous potential due to the wide range of applications. Most plasmas have gas temperatures which greatly exceed room temperature. These are often utilized in electro-surgery for cutting and coagulating tissue. Another type of plasma, referred to as cold atmospheric plasma, or CAP, is characterized by heavy particle temperatures which are at or near room temperature. Due to this lack of thermal effect, CAP may provide less invasive medical procedures. Additionally, CAP have been demonstrated to be effective at targeting cancer cells while minimizing damage to the surrounding tissue. A recently fabricated Microwave Electron Density Device (MEDD) utilizes microwave scattering on small atmospheric plasmas to determine the electron plasma density. The MEDD can be utilized on plasmas which range from a fraction of a millimeter to several centimeters at atmospheric pressure when traditional methods cannot be applied. Microwave interferometry fails due to the small size of the plasma relative to the microwave wavelength which leads to diffraction and negligible phase change; electrostatic probes introduce very strong perturbation and are associated with difficulties of application in strongly-collisional atmospheric conditions; and laser Thomson scattering is not sensitive enough to measure plasma densities less than 1012 cm-3. The first part of this dissertation provides an overview of two types of small atmospheric plasma objects namely CAPs and plasmas utilized in the electro-surgery. It then goes on to describe the fabrication, testing and calibration of the MEDD facility. The second part of this dissertation is focused on the application of the MEDD and other diagnostic techniques to both plasma objects. A series of plasma images that illustrate the temporal evolution of a discharge created by an argon electrosurgical device operating in the coagulation mode and its behavior was analyzed. The discharge of the argon

  14. Characterization of plasma sprayed beryllium ITER first wall mockups

    Energy Technology Data Exchange (ETDEWEB)

    Castro, R.G.; Vaidya, R.U.; Hollis, K.J. [Los Alamos National Lab., NM (United States). Material Science and Technology Div.

    1998-01-01

    ITER first wall beryllium mockups, which were fabricated by vacuum plasma spraying the beryllium armor, have survived 3000 thermal fatigue cycles at 1 MW/m{sup 2} without damage during high heat flux testing at the Plasma Materials Test Facility at Sandia National Laboratory in New Mexico. The thermal and mechanical properties of the plasma sprayed beryllium armor have been characterized. Results are reported on the chemical composition of the beryllium armor in the as-deposited condition, the through thickness and normal to the through thickness thermal conductivity and thermal expansion, the four-point bend flexure strength and edge-notch fracture toughness of the beryllium armor, the bond strength between the beryllium armor and the underlying heat sink material, and ultrasonic C-scans of the Be/heat sink interface. (author)

  15. Characterization of Plasma Sprayed Beryllium ITER First Wall Mockups

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Richard G.; Vaidya, Rajendra U.; Hollis, Kendall J.

    1997-12-31

    ITER first wall beryllium mockups, which were fabricated by vacuum plasma spraying the beryllium armor, have survived 3000 thermal fatigue cycles at 1 MW/sq m without damage during high heat flux testing at the Plasma Materials Test Facility at Sandia National Laboratory in New Mexico. The thermal and mechanical properties of the plasma sprayed beryllium armor have been characterized. Results are reported on the chemical composition of the beryllium armor in the as-deposited condition, the through thickness and normal to the through thickness thermal conductivity and thermal expansion, the four-point bend flexure strength and edge-notch fracture toughness of the beryllium armor, the bond strength between the beryllium armor and the underlying heat sink material, and ultrasonic C-scans of the Be/heat sink interface.

  16. Understanding plasma spraying process and characteristics of DC-arc plasma gun (PJ-100

    Directory of Open Access Journals (Sweden)

    Jovana Ružić

    2012-12-01

    Full Text Available The thermal spray processes are a group of coating processes used to apply metallic or non-metallic coatings. In these processes energy sources are used to heat the coating material (in the form of powder, wire, or rod form to a molten or semi-molten state and accelerated towards a prepared surface by either carrier gases or atomization jets. In plasma spraying process, the spraying material is generally in the form of powder and requires a carrier gas to feed the powder into the plasma jet, which is passing between the hot cathode and the cylindrical nozzle-shaped anode. The design of DC plasma gun (PJ - 100 is designed and manufactured in Serbia. Plasma spaying process, the powder injection with the heat, momentum and mass transfers between particles and plasma jet, and the latest developments related to the production of DC plasma gun are described in this article.

  17. SPRAYTRAN USER'S GUIDE: A GIS-BASED ATMOSPHERIC SPRAY DROPLET DISPERSION MODELING SYSTEM

    Science.gov (United States)

    The offsite drift of pesticide from spray operations is an ongoing source of concern. The SPRAY TRANsport (SPRAYTRAN) system, documented in this report, incorporates the near-field spray application model, AGDISP, into a meso-scale atmospheric transport model. The AGDISP model ...

  18. Steam chemical reactivity of plasma-sprayed beryllium

    Energy Technology Data Exchange (ETDEWEB)

    Anderl, R.A.; Pawelko, R.J.; Smolik, G.R. [Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States). Idaho National Engineering and Environmental Lab.; Castro, R.G. [Los Alamos National Lab., NM (United States)

    1998-07-01

    Plasma-spraying with the potential for in-situ repair makes beryllium a primary candidate for plasma facing and structural components in experimental magnetic fusion machines. Deposits with good thermal conductivity and resistance to thermal cycling have been produced with low pressure plasma-spraying (LPPS). A concern during a potential accident with steam ingress is the amount of hydrogen produced by the reactions of steam with hot components. In this study the authors measure the reaction rates of various deposits produced by LPPS with steam from 350 C to above 1,000 C. They correlate these reaction rates with measurements of density, open porosity and BET surface areas. They find the reactivity to be largely dependent upon effective surface area. Promising results were obtained below 600 C from a 94% theoretical dense (TD) deposit with a BET specific surface area of 0.085 m{sup 2}/g. Although reaction rates were higher than those for dense consolidated beryllium they were substantially lower, i.e., about two orders of magnitude, than those obtained from previously tested lower density plasma-sprayed deposits.

  19. On reactive suspension plasma spraying of calcium titanate

    Czech Academy of Sciences Publication Activity Database

    Kotlan, Jiří; Pala, Zdeněk; Mušálek, Radek; Ctibor, Pavel

    2016-01-01

    Roč. 42, č. 3 (2016), s. 4607-4615 ISSN 0272-8842 R&D Projects: GA ČR GA15-12145S Institutional support: RVO:61389021 Keywords : Suspensions * X-raymethods * Perovskites * Substrates * Suspension plasma spraying Subject RIV: JH - Ceramics , Fire-Resistant Materials and Glass Impact factor: 2.986, year: 2016 http://www.sciencedirect.com/science/article/pii/S0272884215022646

  20. Diagnostics of Thermal Spraying Plasma Jets

    Science.gov (United States)

    Fauchais, P.; Coudert, J. F.; Vardelle, M.; Vardelle, A.; Denoirjean, A.

    D.C. thermal plasma jets are strongly affected on the one hand by the arc root fluctuations at the anode, resulting in a type of pulsed flow and enhanced turbulence, and on the other hand by the entrainment of surrounding cold gas in the plasma jet. These phenomena and the resulting temperature distributions have been studied using a wide range of diagnostic techniques including fast cameras, laser doppler anemometry (LDA), coherent anti-Stokes Raman spectroscopy (CARS), Rayleigh scattering, emission spectroscopy, Schlieren photography, enthalpy probes and sampling probes. The information given by these techniques is evaluated and compared. The effect of the arc fluctuations on the spectroscopic measurements is emphasized and the possibility of using these fluctuations to determine informations on the arc behaviour and the axial velocity of the jet is presented. Optimization of plasma processing of solid particules requires information about their size and surface temperature, as well as number flux and velocity distributions at various locations in the flow field. The different statistical techniques of in-flight measurements are discussed together with their limitations. A method to determine the temperature and species density of the vapor cloud or comet travelling with each particule in flight is then presented. However, such statistical measurements present ambiguities in their interpretation, which can be adressed only by additional measurements to determine the velocity, diameter, and surface temperature of a single particule in flight. Moreover, information on single particules is required in order to understand the coating properties, which depend strongly on the way the particules flatten and solidify upon impact. A method to obtain data related to a single particule in flight and to follow the temperature evolution of the corresponding splat upon cooling is presented. The paper concludes with the description of the experimental techniques to follow the

  1. Suspensions Plasma Spraying of Ceramics with Hybrid Water-Stabilized Plasma Technology

    Czech Academy of Sciences Publication Activity Database

    Mušálek, Radek; Medřický, Jan; Tesař, T.; Kotlan, Jiří; Pala, Zdeněk; Lukáč, František; Chráska, Tomáš; Curry, N.

    2017-01-01

    Roč. 26, 1-2 (2017), s. 37-46 ISSN 1059-9630. [ISTC 2016: International Thermal Spray Conference. Shanghai, 10.05.2016-12.05.2016] R&D Projects: GA ČR GA15-12145S Institutional support: RVO:61389021 Keywords : alumina * ceramics * dense * hybrid plasma torch * suspension plasma spraying * water-stabilized plasma * yttria-stabilized zirconia (YSZ) Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.488, year: 2016 http://link.springer.com/article/10.1007/s11666-016-0493-6

  2. Influence of Bondcoat Spray Process on Lifetime of Suspension Plasma-Sprayed Thermal Barrier Coatings

    Science.gov (United States)

    Gupta, M.; Markocsan, N.; Li, X.-H.; Östergren, L.

    2018-01-01

    Development of thermal barrier coatings (TBCs) manufactured by suspension plasma spraying (SPS) is of high commercial interest as SPS has been shown capable of producing highly porous columnar microstructures similar to the conventionally used electron beam-physical vapor deposition. However, lifetime of SPS coatings needs to be improved further to be used in commercial applications. The bondcoat microstructure as well as topcoat-bondcoat interface topography affects the TBC lifetime significantly. The objective of this work was to investigate the influence of different bondcoat deposition processes for SPS topcoats. In this work, a NiCoCrAlY bondcoat deposited by high velocity air fuel (HVAF) was compared to commercial vacuum plasma-sprayed NiCoCrAlY and PtAl diffusion bondcoats. All bondcoat variations were prepared with and without grit blasting the bondcoat surface. SPS was used to deposit the topcoats on all samples using the same spray parameters. Lifetime of these samples was examined by thermal cyclic fatigue testing. Isothermal heat treatment was performed to study bondcoat oxidation over time. The effect of bondcoat deposition process and interface topography on lifetime in each case has been discussed. The results show that HVAF could be a suitable process for bondcoat deposition in SPS TBCs.

  3. Atmospheric pressure plasma jet applications

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.; Herrmann, H.W.; Henins, I.; Selwyn, G.S. [Los Alamos National Lab., NM (United States)

    1998-12-31

    The atmospheric pressure plasma jet (APPJ) is a non-thermal, high pressure plasma discharge that produces a high velocity effluent stream of highly reactive chemical species. The discharge operates on a feedstock gas (e.g., He/O2/H2O) which flows between two concentric cylindrical electrodes: an outer grounded electrode and an inner electrode powered at 13.56 MHz RF. While passing through the plasma, the feedgas becomes excited, ionized or dissociated by electron impact. The fast-flowing effluent consists of ions and electrons, which are rapidly lost by recombination, highly reactive radicals (e.g., O, OH), and metastable species (e.g., O2). The metastable O2, which is reactive to hydrocarbon and other organic species, has been observed through optical emission spectroscopy to decrease by a factor of 2 from the APPJ nozzle exit to a distance of 10 cm. Unreacted metastable O2, and that which does not impinge on a surface, will then decay back to ordinary ground state O2, resulting in a completely dry, environmentally-benign form of surface cleaning. Applications such as removal of photoresist, oxide films and organic residues from wafers for the electronics industry, decontamination of civilian and military areas and personnel exposed to chemical or biological warfare agents, and paint (e.g., graffiti) removal are being considered.

  4. Studies of the air plasma spraying of zirconia powder

    Energy Technology Data Exchange (ETDEWEB)

    Varacalle, D.J. Jr.; Wilson, G.C. [Vartech, Inc., Idaho Falls, ID (United States); Crawmer, D.E.; Didier, P.A. [Miller Thermal Inc., Appleton, WI (United States)

    1994-12-31

    As part of an investigation of the dynamics that occur in the air plasma spray process, an experimental and analytical study has been accomplished for the deposition of yttria-stabilized zirconia powder using argon-hydrogen and argon-helium working gases. Numerical models of the plasma dynamics and the related plasma-particle interaction are presented. The analytical studies were conducted to determine the parameter space for the empirical studies. Experiments were then conducted using a Box statistical design-of-experiment approach. A substantial range of plasma processing conditions and their effect on the resultant coating is presented. The coatings were characterized by hardness tests and optical metallography (i.e., image analysis). Coating qualities are discussed with respect to hardness, porosity, surface roughness, deposition efficiency, and microstructure. Attributes of the coatings are correlated with the changes in operating parameters. An optimized coating design predicted by the SDE analysis and verified by the calculations is also presented.

  5. Low Temperature Atmospheric Pressure Plasma Sterilization Shower

    Science.gov (United States)

    Gandhiraman, R. P.; Beeler, D.; Meyyappan, M.; Khare, B. N.

    2012-10-01

    Low-temperature atmospheric pressure plasma sterilization shower to address both forward and backward biological contamination issues is presented. The molecular effects of plasma exposure required to sterilize microorganisms is also analysed.

  6. Sintering of Fine Particles in Suspension Plasma Sprayed Coatings

    Directory of Open Access Journals (Sweden)

    Leszek Latka

    2010-07-01

    Full Text Available Suspension plasma spraying is a process that enables the production of finely grained nanometric or submicrometric coatings. The suspensions are formulated with the use of fine powder particles in water or alcohol with some additives. Subsequently, the suspension is injected into plasma jet and the liquid additives evaporate. The remaining fine solids are molten and subsequently agglomerate or remain solid, depending on their trajectory in the plasma jet. The coating’s microstructure results from these two groups of particles arriving on a substrate or previously deposited coating. Previous experimental studies carried out for plasma sprayed titanium oxide and hydroxyapatite coatings enabled us to observe either a finely grained microstructure or, when a different suspension injection mode was used, to distinguish two zones in the microstructure. These two zones correspond to the dense zone formed from well molten particles, and the agglomerated zone formed from fine solid particles that arrive on the substrate in a solid state. The present paper focuses on the experimental and theoretical analysis of the formation process of the agglomerated zone. The experimental section establishes the heat flux supplied to the coating during deposition. In order to achieve this, calorimetric measurements were made by applying experimental conditions simulating the real coatings’ growth. The heat flux was measured to be in the range from 0.08 to 0.5 MW/m2,depending on the experimental conditions. The theoretical section analyzes the sintering during the coating’s growth, which concerns the fine particles arriving on the substrate in the solid state. The models of volume, grain boundary and surface diffusion were analyzed and adapted to the size and chemistry of the grains, temperature and time scales corresponding to the suspension plasma spraying conditions. The model of surface diffusion was found to best describe the sintering during suspension

  7. Atmospheric pressure plasma for surface modification

    CERN Document Server

    Wolf, Rory A

    2012-01-01

    This Book's focus and intent is to impart an understanding of the practical application of atmospheric plasma for the advancement of a wide range of current and emerging technologies. The primary key feature of this book is the introduction of over thirteen years of practical experimental evidence of successful surface modifications by atmospheric plasma methods. It offers a handbook-based approach for leveraging and optimizing atmospheric plasma technologies which are currently in commercial use. It also offers a complete treatment of both basic plasma physics and industrial plasma process

  8. Effect of microstructure and microhardness on the wear resistance of zirconia-alumina, zirconia-yttria and zirconia-ceria coatings manufactured by atmospheric plasma spraying; fecto de la microestructura y de la microdureza sobre la resistencia al desgaste de recubrimientos elaborados por proyeccion termica por plasma atmosferico a partir de circona-alumina, circona-itria y circona-ceria

    Energy Technology Data Exchange (ETDEWEB)

    Giovanni Gonzalez, A.; Ageorges, H.; Rojas, O.; Lopez, E.; Milena Hurtado, F.; Vargas, F.

    2015-10-01

    The effect of the structure and microhardness on the wear resistance of zirconia-alumina (ATZ), zirconia-yttria (YSZ) and zirconia-ceria (CSZ) coatings manufactured by atmospheric plasma spraying was studied. The microstructure and the fracture on the cross section of the coatings were analyzed using Scanning Electron Microscopy, the phases were identified using X-Ray Diffraction, the microhardness was measured by Vickers indentation and the wear resistance was evaluated by ball on disc test. The results showed that zirconia-alumina coating exhibits the best performance in the wear test. This behavior is closely related to their microstructure and higher microhardness, despite of its significant quantity of the monoclinic zirconia phase, which has lower mechanical properties than tetragonal zirconia phase. Tetragonal zirconia phase was predominant in the zirconia-yttria and zirconia-ceria coatings and despite this behavior; they did not have a good performance in the wear tests. This low wear resistance was mainly influenced by the columnar structure within their lamellae, which caused a greater detachment of particles in the contact surface during the ball-disc tests, increasing its wear. (Author)

  9. Acoustic emission study on flexural behaviour of WC-Co coatings obtained by atmospheric plasma spray; Estudio por emision acustica del comportamiento a flexion de recubrimientos WC-Co obtenidos por plasma atomosferico

    Energy Technology Data Exchange (ETDEWEB)

    Segovia, F.; Klyatskina, E.; Bonache, V.; Salvador, M. D.; Sanchez, E.; Cantavella, V.; Bloem, C.

    2007-07-01

    Plasma spayed cermet coatings WC-Co are used in a wide range of industrial applications, mainly due to their wear resistance even in corrosive environments. the objective of this work is to analyze mechanical response of hard metal coatings by means of three-and four-points bend tests applying acoustic emission technique to determine failure critical strength. It has been observed the effect of supported charge level in structural damage by means of optical microscopy and scanning electron microscopy. Acoustic emission has allowed us to relate damage level to stresses level and then to understand coatings failure mechanism. (Author) 29 refs.

  10. Optical study of plasma sprayed hydroxyapatite coatings deposited at different spray distance

    Science.gov (United States)

    Belka, R.; Kowalski, S.; Żórawski, W.

    2017-08-01

    Series of hydroxyapatite (HA) coatings deposited on titanium substrate at different spray (plasma gun to workpiece) distance were investigated. The optical methods as dark field confocal microscopy, Raman/PL and UV-VIS spectroscopy were used for study the influence of deposition process on structural degradation of HA precursor. The hydroxyl group concentration was investigated by study the OH mode intensity in the Raman spectra. Optical absorption coefficients at near UV region were analyzed by Diffuse Reflectance Spectroscopy. PL intensity observed during Raman measurement was also considered as relation to defects concentration and degradation level. It was confirmed the different gunsubstrate distance has a great impact on structure of deposited HA ceramics.

  11. Supersonic Plasma Spray Deposition of CoNiCrAlY Coatings on Ti-6Al-4V Alloy

    Science.gov (United States)

    Caliari, F. R.; Miranda, F. S.; Reis, D. A. P.; Essiptchouk, A. M.; Filho, G. P.

    2017-06-01

    Plasma spray is a versatile technology used for production of environmental and thermal barrier coatings, mainly in the aerospace, gas turbine, and automotive industries, with potential application in the renewable energy industry. New plasma spray technologies have been developed recently to produce high-quality coatings as an alternative to the costly low-pressure plasma-spray process. In this work, we studied the properties of as-sprayed CoNiCrAlY coatings deposited on Ti-6Al-4V substrate with smooth surface ( R a = 0.8 μm) by means of a plasma torch operating in supersonic regime at atmospheric pressure. The CoNiCrAlY coatings were evaluated in terms of their surface roughness, microstructure, instrumented indentation, and phase content. Static and dynamic depositions were investigated to examine their effect on coating characteristics. Results show that the substrate surface velocity has a major influence on the coating properties. The sprayed CoNiCrAlY coatings exhibit low roughness ( R a of 5.7 μm), low porosity (0.8%), excellent mechanical properties ( H it = 6.1 GPa, E it = 155 GPa), and elevated interface toughness (2.4 MPa m1/2).

  12. Influence of Oxidation Behavior of Feedstock on Microstructure and Ablation Resistance of Plasma-Sprayed Zirconium Carbide Coating

    Science.gov (United States)

    Hu, Cui; Ge, Xuelian; Niu, Yaran; Li, Hong; Huang, Liping; Zheng, Xuebin; Sun, Jinliang

    2015-10-01

    Plasma spray is one of the suitable technologies to deposit carbide coatings with high melting point, such as ZrC. However, in the spray processes performed under atmosphere, oxidation of the carbide powder is inevitable. To investigate the influence of the oxidation behavior of feedstock on microstructure and ablation resistance of the deposited coating, ZrC coatings were prepared by atmospheric and vacuum plasma spray (APS and VPS) technologies, respectively. SiC-coated graphite was applied as the substrate. The obtained results showed that the oxidation of ZrC powder in APS process resulted in the formation of ZrO and Zr2O phases. Pores and cracks were more likely to be formed in the as-sprayed APS-ZrC coating. The VPS-ZrC coating without oxides possessed denser microstructure, higher thermal diffusivity, and lower coefficients of thermal expansion as compared with the APS-ZrC coating. A dense ZrO2 layer would be formed on the surface of the VPS-ZrC-coated sample during the ablation process and the substrate can be protected sufficiently after being ablated in high temperature plasma jet. However, the ZrO2 layer, formed by oxidation of the APS-ZrC coating having loose structure, was easy to be washed away by the shearing action of the plasma jet.

  13. Plasma-sprayed dual density ceramic turbine seal system

    Science.gov (United States)

    Clingman, D. L.; Schechter, B.; Cross, K. R.; Cavanagh, J. R.

    1979-01-01

    Dual density, plasma sprayed ceramic coating systems were investigated for possible application as abradable turbine tip seal systems in small gas turbine engines. Abradability, erosion resistance, internal leakage, and microstructural characterization were investigated for polyester and cenosphere filled zirconium oxide composites. Results indicate the polyester system is more abradable but displays significantly less erosion resistance than the cenosphere system. It is also stated that the absence of significant blade tip damage during abradability testing of both systems suggests additional effort may result in a more nearly optimum balance of abradability and erosion resistance.

  14. Young's Moduli of Cold and Vacuum Plasma Sprayed Metallic Coatings

    Science.gov (United States)

    Raj, S. V.; Pawlik, R.; Loewenthal, W.

    2009-01-01

    Monolithic metallic copper alloy and NiCrAlY coatings were fabricated by either the cold spray (CS) or the vacuum plasma spray (VPS) deposition processes. Dynamic elastic modulus property measurements were conducted on these monolithic coating specimens between 300 K and 1273 K using the impulse excitation technique. The Young's moduli decreased almost linearly with increasing temperature at all temperatures except in the case of the CS Cu-23%Cr-5%Al and VPS NiCrAlY, where deviations from linearity were observed above a critical temperature. It was observed that the Young's moduli for VPS Cu-8%Cr were larger than literature data compiled for Cu. The addition of 1%Al to Cu- 8%Cr significantly increased its Young's modulus by 12 to 17% presumably due to a solid solution effect. Comparisons of the Young s moduli data between two different measurements on the same CS Cu- 23%Cr-5%Al specimen revealed that the values measured in the first run were about 10% higher than those in the second run. It is suggested that this observation is due to annealing of the initial cold work microstructure resulting form the cold spray deposition process.

  15. Microstructure characterization of alloy 625 deposited on nickel foam using air plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Azarmi, F.; Saaedi, J.; Coyle, T.W.; Mostaghimi, J. [Center for Advanced Coating Technologies, University of Toronto (Canada)

    2008-05-15

    Ni-based superalloy 625 has been deposited on nickel foam by air plasma spraying (APS) using an optimized set of spraying parameters under two different substrate conditions. For condition (i) the substrate was not cooled during spraying and for condition (ii) the substrate constantly cooled using air jets during spraying. Microstructural characteristics of the as-sprayed coating microstructure were examined by a combination of optical and scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), image analysis, and X-ray diffraction (XRD) analysis, and compared to those of the alloy 625 powder used for spraying. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  16. Plasma Processes: Plasma sprayed alumina coatings for radiation ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 55; Issue 5-6. Plasma ... Conventional design of radiation detectors uses sintered ceramic insulating modules. ... As a result, the design of the beam loss monitor ion chamber for CAT could be simplified by coating the outer surface of the HT electrode with alumina.

  17. Gaseous material capacity of open plasma jet in plasma spray-physical vapor deposition process

    Science.gov (United States)

    Liu, Mei-Jun; Zhang, Meng; Zhang, Qiang; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2018-01-01

    Plasma spray-physical vapor deposition (PS-PVD) process, emerging as a highly efficient hybrid approach, is based on two powerful technologies of both plasma spray and physical vapor deposition. The maximum production rate is affected by the material feed rate apparently, but it is determined by the material vapor capacity of transporting plasma actually and essentially. In order to realize high production rate, the gaseous material capacity of plasma jet must be fundamentally understood. In this study, the thermal characteristics of plasma were measured by optical emission spectrometry. The results show that the open plasma jet is in the local thermal equilibrium due to a typical electron number density from 2.1 × 1015 to 3.1 × 1015 cm-3. In this condition, the temperature of gaseous zirconia can be equal to the plasma temperature. A model was developed to obtain the vapor pressure of gaseous ZrO2 molecules as a two dimensional map of jet axis and radial position corresponding to different average plasma temperatures. The overall gaseous material capacity of open plasma jet, take zirconia for example, was further established. This approach on evaluating material capacity in plasma jet would shed light on the process optimization towards both depositing columnar coating and a high production rate of PS-PVD.

  18. A Study of the Influence of the Surrounding Gas on the Plasma Jet and Coating Quality during Plasma Spraying

    OpenAIRE

    Liu, Taikai; Ansar, Asif; Arnold, Johannes

    2017-01-01

    Coating quality is affected by arc and plume instabilities during plasma spraying. In closed chamber plasma spraying, gradual drift is one of the intermediate instabilities, which is mainly due to the electrode erosion. This work focuses on the source of the gradual drift of the plasma jet and the influence on coating quality. The ambient state inside the chamber was controlled by a ventilation system and a vacuum system. The variation in the plasma jet was observed by a particle flux image (...

  19. Atmospheric plasma processes for environmental applications

    OpenAIRE

    Shapoval, Volodymyr

    2012-01-01

    Plasma chemistry is a rapidly growing field which covers applications ranging from technological processing of materials, including biological tissues, to environmental remediation and energy production. The so called atmospheric plasma, produced by electric corona or dielectric barrier discharges in a gas at atmospheric pressure, is particularly attractive for the low costs and ease of operation and maintenance involved. The high concentrations of energetic and chemically active species (e.g...

  20. Program for plasma-sprayed self-lubricating coatings

    Science.gov (United States)

    Walther, G. C.

    1979-01-01

    A method for preparing composite powders of the three coating components was developed and a procedure that can be used in applying uniform coatings of the composite powders was demonstrated. Composite powders were prepared by adjusting particle sizes of the components and employing a small amount of monoaluminum phosphate as an inorganic binder. Quantitative microscopy (image analysis) was found to be a convenient method of characterizing the composition of the multiphase plasma-sprayed coatings. Area percentages and distribution of the components were readily obtained by this method. The adhesive strength of the coating to a nickel-chromium alloy substrate was increased by about 40 percent by a heat treatment of 20 hours at 650 C.

  1. Electrical model of cold atmospheric plasma gun

    Science.gov (United States)

    Slutsker, Ya. Z.; Semenov, V. E.; Krasik, Ya. E.; Ryzhkov, M. A.; Felsteiner, J.; Binenbaum, Y.; Gil, Z.; Shtrichman, R.; Cohen, J. T.

    2017-10-01

    We present an analytical model of cold atmospheric plasma formed by a dielectric barrier discharge (DBD), which is based on the lumped and distributed elements of an equivalent electric circuit of this plasma. This model is applicable for a wide range of frequencies and amplitudes of the applied voltage pulses, no matter whether or not the generated plasma plume interacts with a target. The model allows quantitative estimation of the plasma plume length and the energy delivered to the plasma. Also, the results of this model can be used for the design of DBD guns which efficiently generate cold atmospheric plasma. A comparison of the results of the model with those obtained in experiments shows a fairly good agreement.

  2. Equipment and technologies of air-plasma spraying of functional coatings

    Directory of Open Access Journals (Sweden)

    Kuzmin Viktor

    2017-01-01

    Full Text Available This article presents a short description of the DC plasma torch "PNK-50" structural features (ITAM SB RAS, Novosibirsk used for spraying of functional coatings with powder materials as well as gives the results of thermophysical and technological studies of spraying regimes. We present preliminary results of the plasma torch supersonic modification development and the results of industrial approbation of the plasma torch and of multi-purposes functional coatings deposition processes.

  3. Microstructure and high temperature cyclic oxidation in atmospheres with variable oxygen contents of plasma and HVOF NiCrBSiFe sprayed coatings; Microestructura y oxidacion ciclica en atmosferas con contenidos de oxigeno variables de un recubrimiento NiCrBSiFe proyectado termicamente por plasma y HVOF

    Energy Technology Data Exchange (ETDEWEB)

    Higuera-Hidalgo, V.; Belzunce-Varela, F. J.; Riba-Lopez, J.

    2006-07-01

    The influence of thermal spraying procedure (plasma and HVOF) on the microstructure, high temperature oxidation resistance and adherence of NiCrSiFe coatings has been examined. Two different series of oxidation tests have been carried out in air (21% oxygen) at 800 and 1,000 degree centigree (1,073 y 1,273 K) and in a simulated gas turbine environment (10% oxygen) representative of a combined-cycle power generation plant, at the same temperatures. Coating microstructure, porosity, oxide content and microhardness are highly dependent on the spraying procedure and coating hardness also significantly decreases after long maintenance at high temperature (1,000 degree centigree). Finally, the oxidation weight gain and the adherence of NiCrBSiFe coatings are also dependent on the morphology of the coating but, nevertheless, the oxidation behaviour of these coatings was very good as protective chromium and silicon oxides were always formed. (Author) 14 refs.

  4. Application of low pressure plasma spray technique to heavy duty gas turbine. Hatsuden yo gas turbine ni okeru gen prime atsu plasma yosha gijutsu no tekiyo

    Energy Technology Data Exchange (ETDEWEB)

    Tsuji, I.; Takahashi, K.; Hirota, N. (Mitsubishi Heavy Industries, Ltd., Tokyo (Japan))

    1990-12-25

    Efficiency of gas turbine depends upon many factors and turbine inlet gas temperature is one of them. In order to obtain high efficiency, it is necessary to increase turbine inlet gas temperature. As the above temperature becomes higher, the surface treatment by plasma spray has been applied as the technique for thermal insulation, antifriction, and hot corrosion resistance. In this article, the low pressure plasma spray (LPPS) equipment, Swiss make, which the Takasago Plant, Mitsubishi Heavy Industries introduced in 1986 and the other one introduced likewise later, the features of LPPS coating and examples of application of LPPS are stated. Concerning LPPS, its powder particle has big impact energy because of its very high flying velocity, hence dense coating is obtained. In case when metallic powder is sprayed, no contamination of the powder is made by oxidation during the spray, and the amount of oxide in the coating is extremely few. Mechanical strength and corrosion resistance of the coating is better than those of atmospheric pressure spray (APS). LPPS is applied to hot corrosion resisting coating and insulation coating, etc. of turbine blades, etc.. 12 figs.

  5. Spray dried plasma as an alternative to antibiotics in piglet feeds, mode of action and biosafety.

    Science.gov (United States)

    Pérez-Bosque, Anna; Polo, Javier; Torrallardona, David

    2016-01-01

    The use of growth promoting and therapeutic antibiotics in piglet feed has been a concerning subject over the last few decades because of the risk of generating antimicrobial resistance that could be transferred to humans. As a result, many products have been proposed as potential alternatives to the use of antibiotics, and among these, spray dried plasma is considered one of the most promising. However, there have been concerns about its biosafety, particularly during periods of emergence or re-emergence of swine diseases in different regions of the world, such as the recent porcine epidemic diarrhea virus outbreak in North America. The objectives of this paper are to review recent publications about the use of spray dried plasma as an alternative to antibiotics in weaned pig diets, the possible mechanisms of action of spray dried plasma, and the existing evidence related to the biosafety of spray dried animal plasma. Particular attention is given to studies in which spray dried plasma has been directly compared to antibiotics or other alternative antimicrobial products. Several studies on the possible modes of action for spray dried plasma, such as preservation of gut barrier function or modulation of the immune response, are also reviewed. Finally, the paper focuses on the review of the existing studies on the risks of disease transmission with the use of spray dried plasma from porcine origin. Overall, spray dried plasma is a promising alternative to in-feed antimicrobials for piglets, particularly during the early stages of the post-weaning phase. Additionally, there is enough evidence to support that commercial spray dried porcine plasma is a safe product for pigs.

  6. Improvement of Ceramic Coatings for Electrostatic Adsorption Force Using Vacuum Plasma Spraying

    Science.gov (United States)

    Takeuchi, Jun-Ichi; Yamasaki, Ryo; Tani, Kazumi; Takahashi, Yasuo

    The purpose of this study is to improve ceramic coatings having a high stable electrostatic adsorption force. The use of the coating is for the Johnsen-Rahbek force type electrostatic chucks used to fix silicon wafers inside vacuum chambers for processes such as Etch, CVD and PVD for semiconductor manufacturers. Previously the authors developed a dielectric substance ceramic coating for electrostatic chucks using Atmospheric Plasma Spraying (APS). This ceramic coating was not suitable because of its unstable electrostatic adsorption force. In a subsequent study, Vacuum Plasma Sprayed (VPS) Al2O3-7.5mass%TiO2 coating was investigated. As a result, it was found that the VPS coating has stable electrical resistivity and adsorption force. The dielectric constant of VPS Al2O3-TiO2 coating was sufficient for application to electrostatic chuck. On the other hand, it was suggested from results with respect to residual adsorption force and duration time after power off that the residual adsorption characteristic was not adequate.

  7. Simulations of Atmospheric Plasma Arcs

    Science.gov (United States)

    Pearcy, Jacob; Chopra, Nirbhav; Jaworski, Michael

    2017-10-01

    We present the results of computer simulation of cylindrical plasma arcs with characteristics similar to those predicted to be relevant in magnetohydrodynamic (MHD) power conversion systems. These arcs, with core temperatures on the order of 1 eV, place stringent limitations on the lifetime of conventional electrodes used in such systems, suggesting that a detailed analysis of arc characteristics will be crucial in designing more robust electrode systems. Simulations utilize results from NASA's Chemical Equilibrium with Applications (CEA) program to solve the Elenbaas-Heller equation in a variety of plasma compositions, including approximations of coal-burning plasmas as well as pure gas discharges. The effect of carbon dioxide injection on arc characteristics, emulating discharges from molten carbonate salt electrodes, is also analyzed. Results include radial temperature profiles, composition maps, and current-voltage (IV) characteristics of these arcs. Work supported by DOE contract DE-AC02-09CH11466.

  8. Fireside Corrosion Behavior of HVOF and Plasma-Sprayed Coatings in Advanced Coal/Biomass Co-Fired Power Plants

    Science.gov (United States)

    Hussain, T.; Dudziak, T.; Simms, N. J.; Nicholls, J. R.

    2013-06-01

    This article presents a systematic evaluation of coatings for advanced fossil fuel plants and addresses fireside corrosion in coal/biomass-derived flue gases. A selection of four candidate coatings: alloy 625, NiCr, FeCrAl and NiCrAlY were deposited onto superheaters/reheaters alloy (T91) using high-velocity oxy-fuel (HVOF) and plasma spraying. A series of laboratory-based fireside corrosion exposures were carried out on these coated samples in furnaces under controlled atmosphere for 1000 h at 650 °C. The tests were carried out using the "deposit-recoat" test method to simulate the environment that was anticipated from air-firing 20 wt.% cereal co-product mixed with a UK coal. The exposures were carried out using a deposit containing Na2SO4, K2SO4, and Fe2O3 to produce alkali-iron tri-sulfates, which had been identified as the principal cause of fireside corrosion on superheaters/reheaters in pulverized coal-fired power plants. The exposed samples were examined in an ESEM with EDX analysis to characterize the damage. Pre- and post-exposure dimensional metrologies were used to quantify the metal damage in terms of metal loss distributions. The thermally sprayed coatings suffered significant corrosion attack from a combination of aggressive combustion gases and deposit mixtures. In this study, all the four plasma-sprayed coatings studied performed better than the HVOF-sprayed coatings because of a lower level of porosity. NiCr was found to be the best performing coating material with a median metal loss of ~87 μm (HVOF sprayed) and ~13 μm (plasma sprayed). In general, the median metal damage for coatings had the following ranking (in the descending order: most to the least damage): NiCrAlY > alloy 625 > FeCrAl > NiCr.

  9. Structure and property evaluation of a vacuum plasma sprayed nanostructured tungsten-hafnium carbide bulk composite

    NARCIS (Netherlands)

    Rea, K. E.; Viswanathan, V.; Kruize, A.; De Hosson, J. Th. M.; O'Dell, S.; McKechnie, T.; Rajagopalan, S.; Vaidyanathan, R.; Seal, S.; O’Dell, S.

    2008-01-01

    Vacuum plasma spray (VPS) forming of tungsten-based metal matrix nanocomposites (MMCs) has shown to be a cost effective and time saving method for the formation of bulk monolithic nanostructured then no-mechanical components. Spray drying of powder feedstock appears to have a significant effect on

  10. Experimental and Numerical Study of the Effect of Gas-Shrouded Plasma Spraying on Cathode Coating of Alkaline Electrolysis Cells

    Science.gov (United States)

    Liu, T.; Reißner, R.; Schiller, G.; Ansar, A.

    2017-11-01

    The aim of this work is to improve the performance of electrodes prepared via atmospheric plasma spray by means of gas shrouding which is expected to apparently reduce the oxygen content of the plasma plume and subsequently improve the coating quality. Electrodes with dual-layer coating for alkaline water electrolysis were deposited on Ni-coated perforated substrates. Microstructure and morphology were studied by SEM. Element content was measured by EDS. Enthalpy probe was employed for measuring plasma temperature and velocity as well as the gas composition. For verifying and better understanding the shrouding effect numerical calculation was carried out according to the experimental settings. Electrochemical test was carried out to validate the shrouding effect. The results showed slight protecting effect of gas shrouding on plasma plume and the final coating. Over the dual-layer section, the measured oxygen fraction was 3.46 and 3.15% for the case without gas shrouding and with gas shrouding, respectively. With gas shrouding the coating exhibited similar element contents as the coating sprayed by VPS, while no obvious improvement was observed in the microstructure or the morphology. Evident electrochemical improvement was nevertheless achieved that with gas shrouding the electrode exhibited similar performance as that of the VPS-sprayed electrode.

  11. Experimental and Numerical Study of the Effect of Gas-Shrouded Plasma Spraying on Cathode Coating of Alkaline Electrolysis Cells

    Science.gov (United States)

    Liu, T.; Reißner, R.; Schiller, G.; Ansar, A.

    2018-01-01

    The aim of this work is to improve the performance of electrodes prepared via atmospheric plasma spray by means of gas shrouding which is expected to apparently reduce the oxygen content of the plasma plume and subsequently improve the coating quality. Electrodes with dual-layer coating for alkaline water electrolysis were deposited on Ni-coated perforated substrates. Microstructure and morphology were studied by SEM. Element content was measured by EDS. Enthalpy probe was employed for measuring plasma temperature and velocity as well as the gas composition. For verifying and better understanding the shrouding effect numerical calculation was carried out according to the experimental settings. Electrochemical test was carried out to validate the shrouding effect. The results showed slight protecting effect of gas shrouding on plasma plume and the final coating. Over the dual-layer section, the measured oxygen fraction was 3.46 and 3.15% for the case without gas shrouding and with gas shrouding, respectively. With gas shrouding the coating exhibited similar element contents as the coating sprayed by VPS, while no obvious improvement was observed in the microstructure or the morphology. Evident electrochemical improvement was nevertheless achieved that with gas shrouding the electrode exhibited similar performance as that of the VPS-sprayed electrode.

  12. Plasma Spray-CVD: A New Thermal Spray Process to Produce Thin Films from Liquid or Gaseous Precursors

    Science.gov (United States)

    Gindrat, M.; Höhle, H.-M.; von Niessen, K.; Guittienne, Ph.; Grange, D.; Hollenstein, Ch.

    2011-06-01

    New dedicated coating processes which are based on the well-known LPPS™ technology but operating at lower work pressure (100 Pa) are being actively developed. These hybrid technologies contribute to improve the efficiencies in the turbine industry such as aero-engines and land-based gas turbines. They also have a great potential in the domain of new energy concepts in applications like Solid Oxide Fuel Cells, membranes, and photovoltaic with the adoption of new ways of producing coatings by thermal spray. Such processes include Plasma Spray-Thin Film (PS-TF) which gives the possibility to coat thin and dense layers from splats through a classical thermal spray approach but at high velocities (400-800 m/s) and enthalpy (8000-15000 kJ/kg). Plasma Spray-PVD (PS-PVD) which allows producing thick columnar-structured Thermal Barrier Coatings (100-300 μm) from the vapor phase with the employment of the high enthalpy gun and specific powder feedstock material. On the other hand, the Plasma Spray-CVD (PS-CVD) process uses modified conventional thermal spray components operated below 100 Pa which allows producing CVD-like coatings (article, we present an overview of the possibilities and limitations encountered while producing thin film coatings using liquid and gaseous precursors with this new type of low pressure plasma spray equipment and point out the challenges faced to obtain efficient injection and mixing of the precursors in the plasma jet. In particular, SiO x thin films from Hexamethyldisiloxane (HMDSO or C6H18OSi2) can be deposited on wafers at deposition rates of up to 35 nm/s at an efficiency of about 50%. The process was also used for producing metal oxide coatings (Al2O3, ZnO, and SnO2) by evaporating different metals in combination with an oxygen gas flow. The effect of process parameters on the deposition rate, coating build up, uniformity, and quality of the coatings are discussed. An overview of different potential applications of this new technology

  13. Vacuum Plasma Spray (VPS) Material Applications for Thruster Components

    Science.gov (United States)

    Elam, Sandra; Holmes, Richard; Hickman, Robert

    2006-01-01

    A variety of vacuum plasma spray (VPS) material systems have been successfully applied to injector and thrust chamber components. VPS offers a versatile fabrication process with relatively low costs to produce near net shape parts. The materials available with VPS increase operating margins and improve component life by providing superior thermal and oxidation protection in specific engine environments. Functional gradient materials (FGM) formed with VPS allow thrust chamber liners to be fabricated with GRCop-84 (an alloy of copper, chrome, and niobium) and a protective layer of NiCrAlY on the hot wall. A variety of thrust chamber liner designs have been fabricated to demonstrate the versatility of the process. Hot-fire test results have confined the improved durability and high temperature performance of the material systems for thrust chamber liners. Similar FGM s have been applied to provide superior thermal protection on injector faceplates with NiCrAlY and zirconia coatings. The durability of the applied materials has been demonstrated with hot-fire cycle testing on injector faceplates in high temperature environments. The material systems can benefit the components used in booster and main engine propulsion systems. More recent VPS efforts are focused on producing rhenium based material systems for high temperature applications to benefit in-space engines like reaction control system (RCS) thrusters.

  14. Filter media properties of mineral fibres produced by plasma spray.

    Science.gov (United States)

    Prasauskas, Tadas; Matulevicius, Jonas; Kliucininkas, Linas; Krugly, Edvinas; Valincius, Vitas; Martuzevicius, Dainius

    2016-01-01

    The purpose of this study was to determine the properties of fibrous gas filtration media produced from mineral zeolite. Fibres were generated by direct current plasma spray. The paper characterizes morphology, chemical composition, geometrical structure of elementary fibres, and thermal resistance, as well as the filtration properties of fibre media. The diameter of the produced elementary fibres ranged from 0.17 to 0.90 μm and the length ranged from 0.025 to 5.1 mm. The release of fibres from the media in the air stream was noticed, but it was minimized by hot-pressing the formed fibre mats. The fibres kept their properties up to the temperature of 956°C, while further increase in temperature resulted in the filter media becoming shrunk and brittle. The filtration efficiency of the prepared filter mats ranged from 95.34% to 99.99% for aerosol particles ranging in a size between 0.03 and 10.0 μm. Unprocessed fibre media showed the highest filtration efficiency when filtering aerosol particles smaller than 0.1 µm. Hot-pressed filters were characterized by the highest quality factor values, ranging from 0.021 to 0.064 Pa(-1) (average value 0.034 Pa(-1)).

  15. Removing biofilms from microstructured titanium ex vivo: a novel approach using atmospheric plasma technology.

    Science.gov (United States)

    Rupf, Stefan; Idlibi, Ahmad Nour; Marrawi, Fuad Al; Hannig, Matthias; Schubert, Andreas; von Mueller, Lutz; Spitzer, Wolfgang; Holtmann, Henrik; Lehmann, Antje; Rueppell, Andre; Schindler, Axel

    2011-01-01

    The removal of biofilms from microstructured titanium used for dental implants is a still unresolved challenge. This experimental study investigated disinfection and removal of in situ formed biofilms from microstructured titanium using cold atmospheric plasma in combination with air/water spray. Titanium discs (roughness (Ra): 1.96 µm) were exposed to human oral cavities for 24 and 72 hours (n = 149 each) to produce biofilms. Biofilm thickness was determined using confocal laser scanning microscopy (n = 5 each). Plasma treatment of biofilms was carried out ex vivo using a microwave-driven pulsed plasma source working at temperatures from 39 to 43°C. Following plasma treatment, one group was air/water spray treated before re-treatment by second plasma pulses. Vital microorganisms on the titanium surfaces were identified by contact culture (Rodac agar plates). Biofilm presence and bacterial viability were quantified by fluorescence microscopy. Morphology of titanium surfaces and attached biofilms was visualized by scanning electron microscopy (SEM). Total protein amounts of biofilms were colorimetrically quantified. Untreated and air/water treated biofilms served as controls. Cold plasma treatment of native biofilms with a mean thickness of 19 µm (24 h) to 91 µm (72 h) covering the microstructure of the titanium surface caused inactivation of biofilm bacteria and significant reduction of protein amounts. Total removal of biofilms, however, required additional application of air/water spray, and a second series of plasma treatment. Importantly, the microstructure of the titanium discs was not altered by plasma treatment. The combination of atmospheric plasma and non-abrasive air/water spray is applicable for complete elimination of oral biofilms from microstructured titanium used for dental implants and may enable new routes for the therapy of periimplant disease.

  16. Removing biofilms from microstructured titanium ex vivo: a novel approach using atmospheric plasma technology.

    Directory of Open Access Journals (Sweden)

    Stefan Rupf

    Full Text Available The removal of biofilms from microstructured titanium used for dental implants is a still unresolved challenge. This experimental study investigated disinfection and removal of in situ formed biofilms from microstructured titanium using cold atmospheric plasma in combination with air/water spray. Titanium discs (roughness (Ra: 1.96 µm were exposed to human oral cavities for 24 and 72 hours (n = 149 each to produce biofilms. Biofilm thickness was determined using confocal laser scanning microscopy (n = 5 each. Plasma treatment of biofilms was carried out ex vivo using a microwave-driven pulsed plasma source working at temperatures from 39 to 43°C. Following plasma treatment, one group was air/water spray treated before re-treatment by second plasma pulses. Vital microorganisms on the titanium surfaces were identified by contact culture (Rodac agar plates. Biofilm presence and bacterial viability were quantified by fluorescence microscopy. Morphology of titanium surfaces and attached biofilms was visualized by scanning electron microscopy (SEM. Total protein amounts of biofilms were colorimetrically quantified. Untreated and air/water treated biofilms served as controls. Cold plasma treatment of native biofilms with a mean thickness of 19 µm (24 h to 91 µm (72 h covering the microstructure of the titanium surface caused inactivation of biofilm bacteria and significant reduction of protein amounts. Total removal of biofilms, however, required additional application of air/water spray, and a second series of plasma treatment. Importantly, the microstructure of the titanium discs was not altered by plasma treatment. The combination of atmospheric plasma and non-abrasive air/water spray is applicable for complete elimination of oral biofilms from microstructured titanium used for dental implants and may enable new routes for the therapy of periimplant disease.

  17. Investigations of some aspects of the spray process in a single wire arc plasma spray system using high speed camera.

    Science.gov (United States)

    Tiwari, N; Sahasrabudhe, S N; Tak, A K; Barve, D N; Das, A K

    2012-02-01

    A high speed camera has been used to record and analyze the evolution as well as particle behavior in a single wire arc plasma spray torch. Commercially available systems (spray watch, DPV 2000, etc.) focus onto a small area in the spray jet. They are not designed for tracking a single particle from the torch to the substrate. Using high speed camera, individual particles were tracked and their velocities were measured at various distances from the spray torch. Particle velocity information at different distances from the nozzle of the torch is very important to decide correct substrate position for the good quality of coating. The analysis of the images has revealed the details of the process of arc attachment to wire, melting of the wire, and detachment of the molten mass from the tip. Images of the wire and the arc have been recorded for different wire feed rates, gas flow rates, and torch powers, to determine compatible wire feed rates. High speed imaging of particle trajectories has been used for particle velocity determination using time of flight method. It was observed that the ripple in the power supply of the torch leads to large variation of instantaneous power fed to the torch. This affects the velocity of the spray particles generated at different times within one cycle of the ripple. It is shown that the velocity of a spray particle depends on the instantaneous torch power at the time of its generation. This correlation was established by experimental evidence in this paper. Once the particles leave the plasma jet, their forward speeds were found to be more or less invariant beyond 40 mm up to 500 mm from the nozzle exit.

  18. Fabrication of copper-based anodes via atmosphoric plasma spraying techniques

    Science.gov (United States)

    Lu, Chun [Monroeville, PA

    2012-04-24

    A fuel electrode anode (18) for a solid oxide fuel cell is made by presenting a solid oxide fuel cell having an electrolyte surface (15), mixing copper powder with solid oxide electrolyte in a mixing step (24, 44) to provide a spray feedstock (30,50) which is fed into a plasma jet (32, 52) of a plasma torch to melt the spray feed stock and propel it onto an electrolyte surface (34, 54) where the spray feed stock flattens into lamellae layer upon solidification, where the layer (38, 59) is an anode coating with greater than 35 vol. % based on solids volume.

  19. Overview on Recent Developments of Bondcoats for Plasma-Sprayed Thermal Barrier Coatings

    Science.gov (United States)

    Naumenko, D.; Pillai, R.; Chyrkin, A.; Quadakkers, W. J.

    2017-12-01

    The performance of MCrAlY (M = Ni, Co) bondcoats for atmospheric plasma-sprayed thermal barrier coatings (APS-TBCs) is substantially affected by the contents of Co, Ni, Cr, and Al as well as minor additions of Y, Hf, Zr, etc., but also by manufacturing-related properties such as coating thickness, porosity, surface roughness, and oxygen content. The latter properties depend in turn on the exact technology and set of parameters used for bondcoat deposition. The well-established LPPS process competes nowadays with alternative technologies such as HVOF and APS. In addition, new technologies have been developed for bondcoats manufacturing such as high-velocity APS or a combination of HVOF and APS for application of a flashcoat. Future developments of the bondcoat systems will likely include optimization of thermal spraying methods for obtaining complex bondcoat roughness profiles required for extended APS-TBC lifetimes. Introduction of the newest generation single-crystal superalloys possessing low Cr and high Al and refractory metals (Re, Ru) contents will require definition of new bondcoat compositions and/or multilayered bondcoats to minimize interdiffusion issues. The developments of new bondcoat compositions may be substantially facilitated using thermodynamic-kinetic modeling, the vast potential of which has been demonstrated in recent years.

  20. Cold Atmosphere Plasma in Cancer Therapy

    Science.gov (United States)

    Keidar, Michael

    2012-10-01

    Plasma is an ionized gas that is typically generated in high-temperature laboratory conditions. Recent progress in atmospheric plasmas led to the creation of cold plasmas with ion temperature close to room temperature. Areas of potential application of cold atmospheric plasmas (CAP) include dentistry, drug delivery, dermatology, cosmetics, wound healing, cellular modifications, and cancer treatment. Various diagnostic tools have been developed for characterization of CAP including intensified charge-coupled device cameras, optical emission spectroscopy and electrical measurements of the discharge propertied. Recently a new method for temporally resolved measurements of absolute values of plasma density in the plasma column of small-size atmospheric plasma jet utilizing Rayleigh microwave scattering was proposed [1,2]. In this talk we overview state of the art of CAP diagnostics and understanding of the mechanism of plasma action of biological objects. The efficacy of cold plasma in a pre-clinical model of various cancer types (long, bladder, and skin) was recently demonstrated [3]. Both in-vitro and in-vivo studies revealed that cold plasmas selectively kill cancer cells. We showed that: (a) cold plasma application selectively eradicates cancer cells in vitro without damaging normal cells. For instance a strong selective effect was observed; the resulting 60--70% of lung cancer cells were detached from the plate in the zone treated with plasma, whereas no detachment was observed in the treated zone for the normal lung cells under the same treatment conditions. (b) Significantly reduced tumor size in vivo. Cold plasma treatment led to tumor ablation with neighbouring tumors unaffected. These experiments were performed on more than 10 mice with the same outcome. We found that tumors of about 5mm in diameter were ablated after 2 min of single time plasma treatment. The two best known cold plasma effects, plasma-induced apoptosis and the decrease of cell migration

  1. Spray-dried plasma and fresh frozen plasma modulate permeability and inflammation in vitro in vascular endothelial cells

    NARCIS (Netherlands)

    Wataha, K.; Menge, T.; Deng, X.; Shah, A.; Bode, A.; Holcomb, J.B.; Potter, D.; Kozar, R.; Spinella, P.C.; Pati, S.

    2013-01-01

    BACKGROUND: After major traumatic injury, patients often require multiple transfusions of fresh frozen plasma (FFP) to correct coagulopathy and to reduce bleeding. A spray-dried plasma (SDP) product has several logistical benefits over FFP use in trauma patients with coagulopathy. These benefits

  2. Plasma-spraying synthesis of high-performance photocatalytic TiO2 coatings

    Science.gov (United States)

    Takahashi, Yasuo; Shibata, Yoshitaka; Maeda, Masakatsu; Miyano, Yasuyuki; Murai, Kensuke; Ohmori, Akira

    2014-08-01

    Anatase (A-) TiO2 is a photocatalytic material that can decompose air-pollutants, acetaldehyde, bacteria, and so on. In this study, three kinds of powder (A-TiO2 without HAp, TiO2 + 10mass%HAp, and TiO2+30mass%HAp, where HAp is hydroxyapatite and PBS is polybutylene succinate) were plasma sprayed on biodegradable PBS substrates. HAp powder was mixed with A-TiO2 powder by spray granulation in order to facilitate adsorption of acetaldehyde and bacteria. The crystal structure was almost completely maintained during the plasma spray process. HAp enhanced the decomposition of acetaldehyde and bacteria by promoting adsorption. A 10mass% HAp content was the most effective for decomposing acetaldehyde when plasma preheating of the PBS was not carried out before the plasma spraying. The plasma preheating of PBS increased the yield rate of the spray process and facilitated the decomposition of acetaldehyde by A-TiO2 coatings without HAp. HAp addition improved photocatalytic sterilization when plasma preheating of the PBS was performed.

  3. Effect of gun current on the microstructure and crystallinity of plasma sprayed hydroxyapatite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Morks, M.F. [Joining and Welding Research Institute, 11-1 Mihogaoka, Ibaraki, 567-0047 Osaka (Japan)]. E-mail: magdimorks@hotmail.com; Kobayashi, A. [Joining and Welding Research Institute, 11-1 Mihogaoka, Ibaraki, 567-0047 Osaka (Japan)

    2007-06-30

    Hydroxyapatite (HA) is a bioactive material because its chemical structure is close to the natural bone. Its bioactive properties make it attractive material in biomedical applications. Gas tunnel type plasma spraying (GTPS) technique was employed in the present study to deposit HA coatings on SUS 304 stainless steel substrate. GTPS is composed of two plasma sources: gun which produces internal low power plasma (1.3-8 kW) and vortex which produces the main plasma with high power level (10-40 kW). Controlling the spraying parameters is the key role for spraying high crystalline HA coatings on the metallic implants. In this study, the arc gun current was changed while the vortex arc current was kept constant at 450 A during the spraying process of HA coatings. The objective of this study is to investigate the influence of gun current on the microstructure, phase crystallinity and hardness properties of HA coatings. The surface morphology and microstructure of as-sprayed coatings were examined by scanning electron microscope. The phase structure of HA coatings was investigated by X-ray diffraction analysis. HA coatings sprayed at high gun current (100 A) are dense, and have high hardness. The crystallinity of HA coatings was decreased with the increasing in the gun current. On the other hand, the hardness was slightly decreased and the coatings suffer from some porosity at gun currents 0, 30 and 50 A.

  4. Atmospheric Pressure Plasma Processing for Polymer Adhesion: A Review

    DEFF Research Database (Denmark)

    Kusano, Yukihiro

    2014-01-01

    Atmospheric pressure plasma processing has attracted significant interests over decades due to its usefulness and a variety of applications. Adhesion improvement of polymer surfaces is among the most important applications of atmospheric pressure plasma treatment. Reflecting recent significant de...

  5. D. C. plasma-sprayed coatings of nano-structured alumina-titania-silica

    CERN Document Server

    Jiang Xian Liang

    2002-01-01

    nano-crystalline powders of omega(Al sub 2 O sub 3) = 95%, omega(TiO sub 2) = 3%, and omega(SiO sub 2) = 2%, were reprocessed into agglomerated particles for plasma spraying, by using consecutive steps of ball milling, slurry forming, spray drying, and heat treatment. D.C. plasma was used to spray the agglomerated nano-crystalline powders, and resultant coatings were deposited on the substrate of stainless steel. Scanning electron microscopy (SEM) was used to examine the morphology of the agglomerated powders and the cross section of the alumina-titania-silica coatings. Experimental results show that the agglomerated nano-crystalline particles are spherical, with a size from (10-90) mu m. The flow ability of the nano-crystalline powders is greatly improved after the reprocessing. The coatings deposited by the plasma spraying are mainly of nano-structure. Unlike conventional plasma-sprayed coatings, no laminar layer could be found in the nano-structured coatings. Although the nano-structured coatings have a lo...

  6. Manufacturing of Electrolyte and Cathode Layers SOFC Using Atmospheric Spraying Method and Its Characterization

    Directory of Open Access Journals (Sweden)

    S. Sulistyo

    2012-12-01

    Full Text Available The use of Solid Oxide Fuel Cell (SOFC has created various interest in many parties, due to its capability to convert gases into electricity. The main requirement of SOFC cell components is to be produced as thin as possible to minimize the losses of electrical resistance, as well as able to support internal and external loads. This paper discusses the procedure of making a thin electrolyte layer, as well as a porous thin layer cathode using atmospheric spraying technique. The procedure of spraying was in room temperature with the process of sintering at temperature of 13500 C held for 3 hours. The SOFC characterization of electrolyte and cathode microstructure was determined by using the SEM, FESEM, XRD and impedance spectroscopy, to measure the impedance of SOFC cells. The results show that the thickness of thin layer electrolyte and porous cathode obtained of about 20 µm and 4 µm, respectively. Also the SOFC cell impedance was measured of 2.3726 x 106 Ω at room temperature. The finding also demonstrated that although the materials (anode, cathode and electrolyte possess different coefficient thermal expansion, there was no evidence of flaking layers which seen the materials remain intact. Thus, the atmospheric spraying method can offer an alternative method to manufacturing of SOFC thin layer electrolyte and cathode. [Key words: SOFC; spraying method; electrolyte; cathode

  7. Plasma spray joining of Al-matrix particulate reinforced composites

    Energy Technology Data Exchange (ETDEWEB)

    Itsukaichi, T.; Eagar, T.W.; Unemoto, M.; Okane, I.

    1996-09-01

    Aluminum matrix composite joints have been produced on both aluminum alloy and metal matrix composite (MMC) substrates using powders containing SiC and Al{sub 2}O{sub 3} particulates. Most of the composite powders were produced by ball milling, but the most effective joints were produced using Osprey composite powders. The results of preliminary joining experiments indicate that the substrate should be preheated to 200 C and a very wide bevel angle should be provided in order to obtain the highest strength joints. Silicon alloy additions to the matrix significantly improved strength but titanium additions had no effect. Heat treatment after spraying significantly improved the bond strength and restored precipitation hardening in the matrix. Significant amounts of Mg were lost from the deposit during spraying while some free silicon was produced by pyrolysis of the SiC powder; hence, further efforts must develop powder compositions that produce the optimum matrix composition in the sprayed deposit. Hot isostatic pressing of the samples to eliminate porosity had only a small effect on the final strength of the joints. No significant amount of Al{sub 4}C{sub 3} was detected in deposits which contained SiC.

  8. Superconducting and structural properties of plasma sprayed YBaCuO layers deposited on metallic substrates

    NARCIS (Netherlands)

    Hemmes, Herman K.; Jäger, D; Smithers, M.A.; Smithers, M.; van der Veer, J.; van der Veer, J.M.; Stover, D.; Rogalla, Horst

    1993-01-01

    The properties of plasma sprayed Y-Ba-Cu-O coatings deposited on metallic substrates are studied. Stainless steel, nickel steels and pure nickel are used as substrate. Y-Ba-Cu-O deposited on stainless steel and nickel steel reacts with the substrate. This interaction can be suppressed by using an

  9. 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.

  10. [In vitro comparison of antibacterial properties of plasma sprayed wollastonite coatings loading silver and gentamicin].

    Science.gov (United States)

    Dong, Yu-qi; Li, Bao-e; Liu, Xuan-yong; Feng, Yu; Cao, Cong

    2008-12-15

    To develop antibacterial coatings for orthopedic implants with a sustained release of drugs. Wollastonite coatings were deposited on the titanium substrates by an atmospheric plasma spray system. After soaking in weight percent of 5% AgNO(3) solution for 24 h, the wollastonite coatings loading silver were obtained. Gentamicin were loaded on the wollastonite coatings by collagen grafting process. The release rates of drugs from wollastonite coatings were investigated by the in vitro solution soaking test. One strain of S. aureus was used in zone of inhibition test to evaluate the antibacterial properties of drug loaded wollastonite coatings, and the cell culture test was used to evaluate their cytotoxicity. Silver and gentamicin loaded wollastonite coatings were successfully prepared. The release of silver ions from the silver loaded wollastonite coatings lasted 50 d in deionized water, effectively inhibiting the growth of S. aureus for 40 d. While an initial burst release of gentamicin was found during the in vitro solution soaking test. The gentamicin released from gentamicin loaded wollastonite coatings can inhibit the growth of S. aureus for 18 d. Both the two kinds of antibacterial wollastonite coatings showed no adverse effect on cellular adhesion, proliferation and alkaline phosphatase expression. Compared with gentamicin loaded wollastonite coatings, silver loaded wollastonite coatings may have more promising clinical applications due to the even and long-time antibacterial agent release.

  11. High-Temperature Solid Lubricant Coating by Plasma Spraying Using Metal-Metal Clad Powders

    Science.gov (United States)

    Zhang, Tiantian; Lan, Hao; Yu, Shouquan; Huang, Chuanbing; Du, Lingzhong; Zhang, Weigang

    2017-08-01

    NiCr/Ag-Mo composite coating was fabricated by atmospheric plasma spray technology using clad powders as the feedstock. Its tribological properties at variable temperature were evaluated using a ball-on-disk high-temperature tribometer in air. The results showed that compared with NiCr, the NiCr/Ag-Mo composite coating exhibited better lubrication effect and higher wear resistance at all test temperatures, especially above 600 °C. At 800 °C, NiCr/Ag-Mo composite coating showed the lowest friction coefficient of about 0.2 and its corresponding wear rate reached 2.5 × 10-5 mm3/Nm. Characterizations of NiCr/Ag-Mo composite coating revealed that at temperatures below 400 °C, Ag was smeared and spread onto the wear surface, reducing the friction and wear. At temperature above 500 °C, the Ag2MoO4 lubrication film formed by tribo-oxidation significantly improved the coating's lubrication effect and wear resistance.

  12. Plasma-Sprayed LSM Protective Coating on Metallic Interconnect of SOFC

    Directory of Open Access Journals (Sweden)

    Jia-Wei Chen

    2017-12-01

    Full Text Available In this study, a (La0.8Sr0.20.98MnO3 protective layer was prepared on the C276, Crofer22 APU, SUS304, and SUS430 alloys by the atmospheric plasma spraying technique (APS. The oxidation behavior and electrical property of these metal alloys have been investigated isothermally at 800 °C in air for up to 300 h. Results showed that the ferritic steels transform into MnCr2O4 spinels and a Cr2O3 layer during isothermal oxidation. The C276 alloy formed NiCr2O4 and FeCr2O4 layers; these are protective and act as an effective barrier against chromium migration into the outer oxide layer, and the alloy demonstrated good oxidation resistance and a reasonable match to the coefficient of thermal expansion of the substrate and a low-oxide scale area-specific resistance. The ASR effects on the formation of oxide scale have been investigated, and the ASR of coated samples was below 0.024 Ω·cm2. It has good electrical conductivity for SOFC in long-term use.

  13. Experimental investigation on erosive wear behaviour of plasma spray coated stainless steel

    Science.gov (United States)

    Girisha, K. G.; Sreenivas Rao, K. V.; Anil, K. C.; Sanman, S.

    2017-04-01

    Slurry erosion is an implicit problem in many engineering industrial components such as ore carrying pipelines, slurry pumps and extruders. Even the water turbine blades are subjected to erosive wear when the water contains considerable amount of silt. In the present study, Al2O3-40%TiO2 powder particles of average particle size of 50 micrometer were deposited on EN56B martenistic stainless steel by atmospheric plasma spray technique. Ni/Cr was pre coated to work as bond coat for good adhesion between coating and the substrate material. A coating thickness of 200 micrometer was achieved. Coated and un-coated substrates were subjected to slurry erosion test as per ASTM G-119 standard. Slurry erosion test rig was used to evaluate the erosion properties at room temperature condition by varying the spindle speed. Scanning electron microphotographs were taken before and after the slurry erosion test. Microstructures reveal uniform distribution of coating materials. Eroded surface shows lip, groove, and crater formation and dense coating resulting in less porosity. Micro hardness test was evaluated and reported. EDX analysis confirms the presence of Al, Ti and O2 particles. It was observed that, Al2O3-40%TiO2 coated substrates exhibit superior erosion resistance as compared to un-coated substrates due to higher hardness and less coating porosity.

  14. Effects of RF plasma treatment on spray-pyrolyzed copper oxide films on silicon substrates

    Science.gov (United States)

    Madera, Rozen Grace B.; Martinez, Melanie M.; Vasquez, Magdaleno R., Jr.

    2018-01-01

    The effects of radio-frequency (RF) argon (Ar) plasma treatment on the structural, morphological, electrical and compositional properties of the spray-pyrolyzed p-type copper oxide films on n-type (100) silicon (Si) substrates were investigated. The films were successfully synthesized using 0.3 M copper acetate monohydrate sprayed on precut Si substrates maintained at 350 °C. X-ray diffraction revealed cupric oxide (CuO) with a monoclinic structure. An apparent improvement in crystallinity was realized after Ar plasma treatment, attributed to the removal of residues contaminating the surface. Scanning electron microscope images showed agglomerated monoclinic grains and revealed a reduction in size upon plasma exposure induced by the sputtering effect. The current–voltage characteristics of CuO/Si showed a rectifying behavior after Ar plasma exposure with an increase in turn-on voltage. Four-point probe measurements revealed a decrease in sheet resistance after plasma irradiation. Fourier transform infrared spectral analyses also showed O–H and C–O bands on the films. This work was able to produce CuO thin films via spray pyrolysis on Si substrates and enhancement in their properties by applying postdeposition Ar plasma treatment.

  15. Heat-Treated TiO2 Plasma Spray Deposition for Bioactivity Improvement in Ti-6Al-4V Alloy

    Science.gov (United States)

    Kumari, Renu; Majumdar, Jyotsna Dutta

    2017-12-01

    In the present study, titanium di-oxide (TiO2) coating has been developed on Ti-6Al-4V substrate by plasma spray deposition. Followed by plasma spraying, heat treatment of the sprayed sample has been carried out by isothermally holding it at 823 K (550 °C) for 2 h. Microstructural analysis shows the presence of porosity and unmelted particles on the as-sprayed surface, the area fraction of which reduces after heat treatment. X-ray diffraction analysis shows the phase transformation from anatase (in precursor powder) to rutile (in as-sprayed coating and the same after heat treatment). There is an improvement in nano-hardness, "Young's modulus" and wear resistance in plasma-sprayed TiO2 coating (as-sprayed as well as post-heat-treated condition) as compared to as-received Ti-6Al-4V, though post-heat treatment offers a superior hardness, "young's modulus" and wear resistance as compared to as-sprayed coating. The corrosion behavior in "hank's solution" shows decrease in corrosion resistance after plasma spraying and post-heat treatment as compared to as-received substrate. A significant decrease in contact angle and improvement in bioactivity (in terms of apatite deposition) were observed in TiO2-coated surface as compared to as-received Ti-6Al-4V.

  16. Novel Prospects for Plasma Spray-Physical Vapor Deposition of Columnar Thermal Barrier Coatings

    Science.gov (United States)

    Anwaar, Aleem; Wei, Lianglinag; Guo, Qian; Zhang, Baopeng; Guo, Hongbo

    2017-12-01

    Plasma spray-physical vapor deposition (PS-PVD) is an emerging coating technique that can produce columnar thermal barrier coatings from vapor phase. Feedstock treatment at the start of its trajectory in the plasma torch nozzle is important for such vapor-phase deposition. This study describes the effects of the plasma composition (Ar/He) on the plasma characteristics, plasma-particle interaction, and particle dynamics at different points spatially distributed inside the plasma torch nozzle. The results of calculations show that increasing the fraction of argon in the plasma gas mixture enhances the momentum and heat flow between the plasma and injected feedstock. For the plasma gas combination of 45Ar/45He, the total enthalpy transferred to a representative powder particle inside the plasma torch nozzle is highest ( 9828 kJ/kg). Moreover, due to the properties of the plasma, the contribution of the cylindrical throat, i.e., from the feed injection point (FIP) to the start of divergence (SOD), to the total transferred energy is 69%. The carrier gas flow for different plasma gas mixtures was also investigated by optical emission spectroscopy (OES) measurements of zirconium emissions. Yttria-stabilized zirconia (YSZ) coating microstructures were produced when using selected plasma gas compositions and corresponding carrier gas flows; structural morphologies were found to be in good agreement with OES and theoretical predictions. Quasicolumnar microstructure was obtained with porosity of 15% when applying the plasma composition of 45Ar/45He.

  17. Novel Prospects for Plasma Spray-Physical Vapor Deposition of Columnar Thermal Barrier Coatings

    Science.gov (United States)

    Anwaar, Aleem; Wei, Lianglinag; Guo, Qian; Zhang, Baopeng; Guo, Hongbo

    2017-09-01

    Plasma spray-physical vapor deposition (PS-PVD) is an emerging coating technique that can produce columnar thermal barrier coatings from vapor phase. Feedstock treatment at the start of its trajectory in the plasma torch nozzle is important for such vapor-phase deposition. This study describes the effects of the plasma composition (Ar/He) on the plasma characteristics, plasma-particle interaction, and particle dynamics at different points spatially distributed inside the plasma torch nozzle. The results of calculations show that increasing the fraction of argon in the plasma gas mixture enhances the momentum and heat flow between the plasma and injected feedstock. For the plasma gas combination of 45Ar/45He, the total enthalpy transferred to a representative powder particle inside the plasma torch nozzle is highest ( 9828 kJ/kg). Moreover, due to the properties of the plasma, the contribution of the cylindrical throat, i.e., from the feed injection point (FIP) to the start of divergence (SOD), to the total transferred energy is 69%. The carrier gas flow for different plasma gas mixtures was also investigated by optical emission spectroscopy (OES) measurements of zirconium emissions. Yttria-stabilized zirconia (YSZ) coating microstructures were produced when using selected plasma gas compositions and corresponding carrier gas flows; structural morphologies were found to be in good agreement with OES and theoretical predictions. Quasicolumnar microstructure was obtained with porosity of 15% when applying the plasma composition of 45Ar/45He.

  18. The change of NiCrBSi alloys’ phase composition after plasma spraying

    Directory of Open Access Journals (Sweden)

    A. Dudek

    2008-08-01

    Full Text Available Material for investigations was NiCrBSi powder for components’ coatings which improve their corrosion resistance as well as resistance to friction wear and erosion. Plasma spraying method was used to produce a coating with thickness of 300 μm on low-alloy steel which was then remelted with the base material. Using X-ray quality analysis, phase composition was determined for: NiCrBSi powder, obtained coating and the alloyed surface layer. Crystallinity degree was also calculated for NiCrBSi layer sprayed on the base material.

  19. Comparison of Physical-chemical and Mechanical Properties of Chlorapatite and Hydroxyapatite Plasma Sprayed Coatings.

    Science.gov (United States)

    Demnati, Imane; Grossin, David; Marsan, Olivier; Bertrand, Ghislaine; Collonges, Gérard; Combes, Christèle; Parco, Maria; Braceras, Inigo; Alexis, Joel; Balcaen, Yannick; Rey, Christian

    2015-01-01

    Chlorapatite can be considered a potential biomaterial for orthopaedic applications. Its use as plasma-sprayed coating could be of interest considering its thermal properties and particularly its ability to melt without decomposition unlike hydroxyapatite. Chlorapatite (ClA) was synthesized by a high-temperature ion exchange reaction starting from commercial stoichiometric hydroxyapatites (HA). The ClA powder showed similar characteristics as the original industrial HA powder, and was obtained in the monoclinic form. The HA and ClA powders were plasma-sprayed using a low-energy plasma spraying system with identical processing parameters. The coatings were characterized by physical-chemical methods, i.e. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy, including distribution mapping of the main phases detected such as amorphous calcium phosphate (ACP), oxyapatite (OA), and HA or ClA. The unexpected formation of oxyapatite in ClA coatings was assigned to a side reaction with contaminating oxygenated species (O2, H2O). ClA coatings exhibited characteristics different from HA, showing a lower content of oxyapatite and amorphous phase. Although their adhesion strength was found to be lower than that of HA coatings, their application could be an interesting alternative, offering, in particular, a larger range of spraying conditions without formation of massive impurities.

  20. Conception of a novel spray tower plasma-reactor in a spatial post-discharge configuration: Pollutants remote treatment.

    Science.gov (United States)

    Ferhat, Mohamed Fouad; Ghezzar, Mouffok Redouane; Smaïl, Bentaïba; Guyon, Cedric; Ognier, Stéphanie; Addou, Ahmed

    2017-01-05

    This paper describes a novel gliding Arc discharge reactor producing a non-thermal plasma at atmospheric pressure in humid air. The ionized gas is generated in a spray-tower absorber for the treatment of organic pollutants. The reactor configuration enables the plasma-degradation of micro-droplets effluents in the spatial post-discharge mode. This type of design allows to exclude the direct contact between the plasma plume and the liquid to be treated in order to avoid the liquid heating and the flame extinction problems. A hydrodynamic study coupling 'Navier-Stokes' equations and those of 'Convection-Diffusion' allowed to calculate the concentration profiles and the droplet falling velocity. The stripping of phenol was studied to valid the hydrodynamic approach. Experiences and simulations showed that after 1h of treatment, only 5% of the compound was transferred into the plasma phase. The spatiality of the novel reactor allowed a degradation rate of 100% for catechol after 38min of plasma-treatment. For 4-nitrophenol, the degradation rate reached 90% after 120min. Phenol and its by-products degradation were totally degraded by combining the spatiality of the reactor and the temporal post-discharge. A degradation mechanism was proposed and a plasmachemical reaction in relation with the pernitrous acid species was confirmed. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Failure behaviors of vacuum plasma sprayed tungsten coatings for plasma facing application

    Science.gov (United States)

    Chong, F. L.; Chen, J. L.; Li, J. G.; Zheng, X. B.

    2009-04-01

    About 1 mm vacuum plasma sprayed tungsten (VPS-W) coatings were fabricated on the copper chromium zirconium (CuCrZr) alloys substrate. The failure behaviors were studied by means of the steady state and transient heat load using the electron beam facility and the Nd: YAG laser, respectively. The results indicated that the columnar crystals grew up and then micro-cracks between the lamellar layers were observed. Macro-cracks and delamination appeared with the fatigue cycles increase. Finally, the coating failed. The surface cracks were also observed and propagated during the fatigue tests. The failure behaviors of the transient heat load are as follows: the homogeneous melting and micro-cracks, melting tungsten ejection which enhanced the erosion of tungsten due to the splash and evaporation. In addition, the physical properties of W coatings such as porosity, Vickers hardness were degraded. The roughing phenomenon was not easy to be observed due to the rough surface characteristic of VPS-W coatings.

  2. DEVELOPMENT OF COMPLEX EQUIPMENT FOR PLASMA SPRAY CERAMIC COATINGS

    Directory of Open Access Journals (Sweden)

    V. V. Okovity

    2017-01-01

    Full Text Available Develop a set equipment for plasma forming ceramic coatings. The article presents characteristics and parameters of the developed complex equipment for formation of plasma ceramic coatings as well as results of its testing. Methods of research is based on studies of structural elements composite plasma coatings system ZrO2 – Y2O3  obtained  using  developed complex equipment. One of the most effective ways to protect the components from high temperature corrosion and oxidation is formation on the surface of plasma thermal barrier coatings. For thermal barrier coating has very strict requirements: сharacterized by a smooth change of physico-mechanical properties (porosity, microhardness, elastic modulus in the cross section of the metal substrate to the outer ceramic layer; to withstand multiple cycles of thermal cycling from room temperature to the operating temperature; to maintain gastightness under operating conditions and thus ensure a sufficiently high level of adhesive strength. For realization of new technological schemes applying thermal barrier coatings with high operational characteristics was developed, patented and manufactured a range of new equipment. The experiments show that authors developed PBG-1 plasmatron and powder feeder PPBG-04 have at least 2–3 times the service life during the deposition of ceramic materials compared to the standard equipment of the company "Plasma-Technik", by changing the structure of the cathode-anode plasma torch assembly and construction of the delivery unit of the feeder to facilitate the uniform supply of the powder into the plasma jet and the best of his penetration. The result is better plasma coatings with improved operational characteristics: adhesion strength is increased to 1.3–2 times, material utilization in 1.5–1.6 times microhardness 1.2–1.4 times the porosity is reduced by 2–2.5 times.

  3. Effect of Post-spray Shot Peening Treatment on the Corrosion Behavior of NiCr-Mo Coating by Plasma Spraying of the Shell-Core-Structured Powders

    Science.gov (United States)

    Tian, Jia-Jia; Wei, Ying-Kang; Li, Cheng-Xin; Yang, Guan-Jun; Li, Chang-Jiu

    2018-01-01

    Corrosion of metal plays a detrimental role in service lifetime of parts or systems. Therefore, coating a protective film which is fully dense and defects free on the base metal is an effective approach to protect the base metal from corrosion. In this study, a dense NiCr-20Mo coating with excellent lamellar interface bonding was deposited by plasma spraying of the novel shell-core-structured Mo-clad-NiCr powders, and then post-spray shot peening treatment by cold spraying of steel shots was applied to the plasma-sprayed NiCr-20Mo coating to obtain a fully dense coating through eliminating possibly existed pores and un-bonded interfaces within the NiCr-20Mo coating. Corrosion behaviors of the NiCr-20Mo coatings before and after shot peening were tested to investigate the effect of the post-spray shot peening on the corrosion behavior of the NiCr-20Mo coating. Results showed that a much dense and uniform plasma-sprayed NiCr-20Mo coating with perfect lamellar bonding at most of interfaces was deposited. However, the electrochemical tests revealed the existence of through-thickness pores in the as-plasma-sprayed NiCr-20Mo coating. Through the post-spray shot peening treatment, a completely dense top layer in the coating was formed, and with the increase in the shot peening intensity from one pass to three passes, the dense top layer became thicker from 100 μm to reach 300 μm of the whole coating thickness. Thus, a fully dense bulk-like coating was obtained. Corrosion test results showed that the dense coating layer resulting from densification of shot peening can act as an effective barrier coating to prevent the penetration of the corrosive medium and consequently protect the substrate from corrosion effectively. Therefore, a fully dense bulk-like NiCr-20Mo coating with excellent corrosion resistance can be achieved through the plasma spraying of Mo-clad-NiCr powders followed by appropriate post-spray shot peening treatment.

  4. Effect of Post-spray Shot Peening Treatment on the Corrosion Behavior of NiCr-Mo Coating by Plasma Spraying of the Shell-Core-Structured Powders

    Science.gov (United States)

    Tian, Jia-Jia; Wei, Ying-Kang; Li, Cheng-Xin; Yang, Guan-Jun; Li, Chang-Jiu

    2017-11-01

    Corrosion of metal plays a detrimental role in service lifetime of parts or systems. Therefore, coating a protective film which is fully dense and defects free on the base metal is an effective approach to protect the base metal from corrosion. In this study, a dense NiCr-20Mo coating with excellent lamellar interface bonding was deposited by plasma spraying of the novel shell-core-structured Mo-clad-NiCr powders, and then post-spray shot peening treatment by cold spraying of steel shots was applied to the plasma-sprayed NiCr-20Mo coating to obtain a fully dense coating through eliminating possibly existed pores and un-bonded interfaces within the NiCr-20Mo coating. Corrosion behaviors of the NiCr-20Mo coatings before and after shot peening were tested to investigate the effect of the post-spray shot peening on the corrosion behavior of the NiCr-20Mo coating. Results showed that a much dense and uniform plasma-sprayed NiCr-20Mo coating with perfect lamellar bonding at most of interfaces was deposited. However, the electrochemical tests revealed the existence of through-thickness pores in the as-plasma-sprayed NiCr-20Mo coating. Through the post-spray shot peening treatment, a completely dense top layer in the coating was formed, and with the increase in the shot peening intensity from one pass to three passes, the dense top layer became thicker from 100 μm to reach 300 μm of the whole coating thickness. Thus, a fully dense bulk-like coating was obtained. Corrosion test results showed that the dense coating layer resulting from densification of shot peening can act as an effective barrier coating to prevent the penetration of the corrosive medium and consequently protect the substrate from corrosion effectively. Therefore, a fully dense bulk-like NiCr-20Mo coating with excellent corrosion resistance can be achieved through the plasma spraying of Mo-clad-NiCr powders followed by appropriate post-spray shot peening treatment.

  5. Fabrication of High-Temperature Heat Exchangers by Plasma Spraying Exterior Skins on Nickel Foams

    Science.gov (United States)

    Hafeez, P.; Yugeswaran, S.; Chandra, S.; Mostaghimi, J.; Coyle, T. W.

    2016-06-01

    Thermal-sprayed heat exchangers were tested at high temperatures (750 °C), and their performances were compared to the foam heat exchangers made by brazing Inconel sheets to their surface. Nickel foil was brazed to the exterior surface of 10-mm-thick layers of 10 and 40 PPI nickel foam. A plasma torch was used to spray an Inconel coating on the surface of the foil. A burner test rig was built to produce hot combustion gases that flowed over exposed face of the heat exchanger. Cooling air flowed through the foam heat exchanger at rates of up to 200 SLPM. Surface temperature and air inlet/exit temperature were measured. Heat transfer to air flowing through the foam was significantly higher for the thermally sprayed heat exchangers than for the brazed heat exchangers. On an average, thermally sprayed heat exchangers show 36% higher heat transfer than conventionally brazed foam heat exchangers. At low flow rates, the convective resistance is large (~4 × 10-2 m2 K/W), and the effect of thermal contact resistance is negligible. At higher flow rates, the convective resistance decreases (~2 × 10-3 m2 K/W), and the lower contact resistance of the thermally sprayed heat exchanger provides better performance than the brazed heat exchangers.

  6. Anisotropic Thermal Diffusivities of Plasma-Sprayed Thermal Barrier Coatings

    Science.gov (United States)

    Akoshima, Megumi; Takahashi, Satoru

    2017-09-01

    Thermal barrier coatings (TBCs) are used to shield the blades of gas turbines from heat and wear. There is a pressing need to evaluate the thermal conductivity of TBCs in the thermal design of advanced gas turbines with high energy efficiency. These TBCs consist of a ceramic-based top coat and a bond coat on a superalloy substrate. Usually, the focus is on the thermal conductivity in the thickness direction of the TBC because heat tends to diffuse from the surface of the top coat to the substrate. However, the in-plane thermal conductivity is also important in the thermal design of gas turbines because the temperature distribution within the turbine cannot be ignored. Accordingly, a method is developed in this study for measuring the in-plane thermal diffusivity of the top coat. Yttria-stabilized zirconia top coats are prepared by thermal spraying under different conditions. The in-plane and cross-plane thermal diffusivities of the top coats are measured by the flash method to investigate the anisotropy of thermal conduction in a TBC. It is found that the in-plane thermal diffusivity is higher than the cross-plane one for each top coat and that the top coats have significantly anisotropic thermal diffusivity. The cross-sectional and in-plane microstructures of the top coats are observed, from which their porosities are evaluated. The thermal diffusivity and its anisotropy are discussed in detail in relation to microstructure and porosity.

  7. Investigation of Droplet Atomization and Evaporation in Solution Precursor Plasma Spray Coating

    Directory of Open Access Journals (Sweden)

    Hongbing Xiong

    2017-11-01

    Full Text Available Solution precursor plasma spray (SPPS is a novel and promising technique in producing nanostructured coatings. This technique involves complex heat, mass and momentum transfer among the liquid feedstock, droplets, plasma jet and the coating material. Nevertheless, the droplet atomization and evaporation in the plasma jet is one of the most essential parts to obtain the desired coating architecture. In the present work, a three-dimensional two-way-coupled Eulerian-Lagrangian code is used to simulate the interactions between the solution precursor and plasma. In order to obtain a more realistic understanding regarding droplet atomization and vaporization, the flash-boiling effect is modeled by an improved vaporization model. This model could provide accurate details for the droplet pyrolysis and help to optimize the solution precursor plasma spray process. We show that the fragmentation of the liquid stock and its vaporization mainly dominate the spraying details and can be decisive to the coating quality. We further investigate their role in SPPS and separately probe their inner link with the flow field relating to the distinctive area when droplets are flying through the thermal flow field. Our studies reveal that ethanol droplets, compared to those of water, show a superior characteristics in SPPS, owing to the low boiling point and low surface tension, conducive to the evaporation and atomization of droplets. In addition, the mixture of the plasma gas with hydrogen breaks the droplets more thoroughly compared to the pure plasma. The numerical results were compared and found to agree well with previous experimental and simulation work.

  8. Unlubricated Gross Slip Fretting Wear of Metallic Plasma Sprayed Coatings for Ti6A14V Surfaces

    National Research Council Canada - National Science Library

    Hager, Jr., Carl H; Sanders, Jeffrey H; Sharma, Shashi K

    2006-01-01

    ... to simulate cold engine startup. Alternative coatings such as plasma sprayed molybdenum and nickel were also evaluated because of their potential for reducing fretting wear under certain simulated engine conditions...

  9. Self-lubricating plasma-sprayed composites for sliding contact bearings to 900 C

    Science.gov (United States)

    Sliney, H. E.

    1974-01-01

    Plasma-sprayed composites which have good oxidation-resistance and self-lubricating characteristics to 900 C were developed. The composites are a Nichrome matrix containing dispersed glass for oxidation protection and calcium fluoride for lubrication. They are applied to bearing surfaces in layers about 0.050 cm thick by plasma-spraying; the layers are then machined to a thickness of 0.025 cm. Oscillating bearing tests were performed in air to 900 C at unit radial loads up to 3.5 times 10 to the 7th power Newtons per square meter (5000 psi) and a thrust load of 1960 Newtons (440 lb). Bearings with a composite liner in the bore were in good condition after over 50,000 oscillating cycles accumulated during repeated bearing temperature cycles between 25 and 900 C.

  10. Vacuum Plasma Spray Forming of Copper Alloy Liners for Regeneratively Cooled Liquid Rocket Combustion Chambers

    Science.gov (United States)

    Zimmerman, Frank

    2003-01-01

    Vacuum plasma spray (VPS) has been demonstrated as a method to form combustion chambers from copper alloys NARloy-Z and GRCop-84. Vacuum plasma spray forming is of particular interest in the forming of CuCrNb alloys such as GRCop-84, developed by NASA s Glenn Research Center, because the alloy cannot be formed using conventional casting and forging methods. This limitation is related to the levels of chromium and niobium in the alloy, which exceed the solubility limit in copper. Until recently, the only forming process that maintained the required microstructure of CrNb intermetallics was powder metallurgy formation of a billet from powder stock, followed by extrusion. This severely limits its usefulness in structural applications, particularly the complex shapes required for combustion chamber liners. This paper discusses the techniques used to form combustion chambers from CuCrNb and NARloy-Z, which will be used in regeneratively cooled liquid rocket combustion chambers.

  11. Foundations of atmospheric pressure non-equilibrium plasmas

    Science.gov (United States)

    Bruggeman, Peter J.; Iza, Felipe; Brandenburg, Ronny

    2017-12-01

    Non-equilibrium plasmas have been intensively studied over the past century in the context of material processing, environmental remediation, ozone generation, excimer lamps and plasma display panels. Research on atmospheric pressure non-equilibrium plasmas intensified over the last two decades leading to a large variety of plasma sources that have been developed for an extended application range including chemical conversion, medicine, chemical analysis and disinfection. The fundamental understanding of these discharges is emerging but there remain a lot of unexplained phenomena in these intrinsically complex plasmas. The properties of non-equilibrium plasmas at atmospheric pressure span over a huge range of electron densities as well as heavy particle and electron temperatures. This paper provides an overview of the key underlying processes that are important for the generation and stabilization of atmospheric pressure non-equilibrium plasmas. The unique physical and chemical properties of theses discharges are also summarized.

  12. Nonthermal Atmospheric Plasmas in Dental Restoration

    Science.gov (United States)

    Liu, Y.; Liu, Q.; Yu, Q.S.; Wang, Y.

    2016-01-01

    It is well known that the service life of contemporary composite restoration is unsatisfactory, and longevity of dentin bonding is one of the major culprits. Bonding is essentially a hybridization process in which dental substrate and adhesive resin interact with each other through an exchange process. Thus, the longevity of dentin bonding can only be improved with enhanced qualities in substrate, adhesive resin, and their interaction within the hybridization zone. This review aims to collect and summarize recent advances in utilizing nonthermal atmospheric plasmas (NTAPs)—a novel technology that delivers highly reactive species in a gaseous medium at or below physiologic temperature—to improve the durability of dentin bonding by addressing these 3 issues simultaneously. Overall, NTAP has demonstrated efficacies in improving a number of critical properties for dentin bonding, including deactivation of oral pathogens, modification of surface chemistry/properties, resin polymerization, improvement in adhesive-dentin interactions, and establishment of auxiliary bonding mechanism. While a few preliminary studies have indicated the benefit of NTAP to bond strength and stability, additional researches are warranted to employ knowledge acquired so far and to evaluate these properties in a systematic way. PMID:26848068

  13. Strontium Zirconate TBC Sprayed by a High Feed-Rate Water-Stabilized Plasma Torch.

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Nevrlá, Barbara; Čížek, Jan; Lukáč, František

    2017-01-01

    Roč. 26, č. 8 (2017), s. 1804-1809 ISSN 1059-9630 R&D Projects: GA TA ČR(CZ) TE02000011 Institutional support: RVO:61389021 Keywords : adhesion * plasma spraying * strontium zirconate * thermal insulator Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.488, year: 2016 https://link.springer.com/article/10.1007/s11666-017-0641-7

  14. Underwater plasma arc spraying - a new technological variant. Unterwasserplasmaspritzen - eine neue Verfahrensvariante

    Energy Technology Data Exchange (ETDEWEB)

    Lugscheider, E.; Bugsel, B. (Technische Hochschule Aachen (Germany, F.R.). Lehr- und Forschungsgebiet Werkstoffwissenschaften)

    1989-10-01

    Besides the known and successful highly energetic coating method, underwater plasma spraying represents another alternative. At first, the development took place for small water depths, with the aim of coating improvement and process humanization. Fundamental investigations concern the determination of those influence factors with relation to material science and process engineering which are significant for an optimum and reproducible design of coating-basic material composites under water. (orig.).

  15. Plasma sprayed manganeseecobalt spinel coatings: Process sensitivity on phase, electrical and protective performance

    Czech Academy of Sciences Publication Activity Database

    Han Jung, S.; Pala, Zdeněk; Sampath, S.

    2016-01-01

    Roč. 304, February (2016), s. 234-243 ISSN 0378-7753 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389021 Keywords : Interconnect protection * Cr-poisoning * Manganese cobalt spinel * Electrical conductivity * Plasma spray Subject RIV: JE - Non-nuclear Energetics, Energy Consumption ; Use Impact factor: 6.395, year: 2016 http://www.sciencedirect.com/science/article/pii/S0378775315305383

  16. Comparative Evaluation of Osseointegration of Dental Endodontic Implants with and without Plasma- Sprayed Hydroxy apatite Coating

    OpenAIRE

    Moosavi SB.; Fathi MH. BS; MSC; Feizi Gh; Mortazavi V

    2001-01-01

    Bone osseointegration around dental implant can cause earlier stabilization and fixation of implant and reduce healing time. Hydroxyapatite coating can affect bone osseointegration and enhance its rates. The aim of this study was comparison of osseointegration between plasma sprayed hydroxyapatite coated and uncoated dental implants in cats. Four endodontic implants including, vitallium and two stainless steel with and without hydroxyapatite coating were prepared and placed in mandibular cani...

  17. Vacuum Plasma Spraying W-coated Reduced Activation Structural Steels for Fusion Plasma Facing Components

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Sanghoon; Kim, Tae Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Tungsten (W) and its alloys are considered as candidate materials for plasma facing materials of the first wall and diverter components in fusion reactor systems because of high sputtering resistance and low tritium retention in a fusion environment. Therefore, it is considered that the joining between W and reduced activation structural steels, and its evaluation, are critical issues for the development of fusion reactors. However, the joining between these materials is a very challenging process because of significant differences in their physical properties, particularly the mismatch of coefficients of thermal expansion (CTE). For instance, the CTE of pure W is known to be about 4.3Χ10{sup -6}K{sup -1}; however, that of martensitic steels reaches over three times, about 12-14Χ10{sup -6}K{sup -1} at room temperature even up to 373K. Nevertheless, several joining techniques have been developed for joining between W and structural steels, such as a vapor deposition method, brazing and diffusion bonding. Meanwhile, vacuum plasma spraying (VPS) is supposed to be one of the prospective methods to fabricate a sufficient W layer on the steel substrates because of the coating of a large area with a relatively high fabricating rate. In this study, the VPS method of W powders on reduced activation steels was employed, and its microstructure and hardness distribution were investigated. ODS ferritic steels and F82H steel were coated by VPS-W, and the microstructure and hardness distribution were investigated. A microstructure analysis revealed that pure W was successfully coated on steel substrates by the VPS process without an intermediate layer, in spite of a mismatch of the CTE between dissimilar materials. After neutron irradiation, irradiation hardening significantly occurred in the VPSW. However, the hardening of VPS-W was lesser than that of bulk W irradiated HFIR at 773K. Substrate materials, ODS ferritic steels, and F82H steel, did not show irradiation hardening

  18. Liquid Feedstock Plasma Spraying: An Emerging Process for Advanced Thermal Barrier Coatings

    Science.gov (United States)

    Markocsan, Nicolaie; Gupta, Mohit; Joshi, Shrikant; Nylén, Per; Li, Xin-Hai; Wigren, Jan

    2017-08-01

    Liquid feedstock plasma spraying (LFPS) involves deposition of ultrafine droplets of suspensions or solution precursors (typically ranging from nano- to submicron size) and permits production of coatings with unique microstructures that are promising for advanced thermal barrier coating (TBC) applications. This paper reviews the recent progress arising from efforts devoted to development of high-performance TBCs using the LFPS approach. Advancements in both suspension plasma spraying and solution precursor plasma spraying, which constitute the two main variants of LFPS, are presented. Results illustrating the different types of the microstructures that can be realized in LFPS through appropriate process parameter control, model-assisted assessment of influence of coating defects on thermo-mechanical properties and the complex interplay between pore coarsening, sintering and crystallite growth in governing thermal conductivity are summarized. The enhancement in functional performances/lifetime possible in LFPS TBCs with multilayered architectures and by incorporating new pyrochlore chemistries such as gadolinium zirconate, besides the conventional single 8 wt.% yttria-stabilized zirconia insulating ceramic layer, is specifically highlighted.

  19. Charge dependence of the plasma travel length in atmospheric-pressure plasma

    Energy Technology Data Exchange (ETDEWEB)

    Yambe, Kiyoyuki; Konda, Kohmei; Masuda, Seiya [Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan)

    2016-06-15

    Plasma plume is generated using a quartz tube, helium gas, and foil electrode by applying AC high voltage under the atmosphere. The plasma plume is released into the atmosphere from inside of the quartz tube and is seen as the continuous movement of the plasma bullet. The travel length of plasma bullet is defined from plasma energy and force due to electric field. The drift velocity of plasma bullet has the upper limit under atmospheric-pressure because the drift velocity is determined from the balance between electric field and resistive force due to collisions between plasma and air. The plasma plume charge depends on the drift velocity. Consequently, in the laminar flow of helium gas flow state, the travel length of the plasma plume logarithmically depends on the plasma plume charge which changes with both the electric field and the resistive force.

  20. Contact-free cold atmospheric plasma treatment of Deinococcus radiodurans.

    Science.gov (United States)

    Maisch, Tim; Shimizu, Tetsuji; Mitra, Anindita; Heinlin, Julia; Karrer, Sigrid; Li, Yang-Fang; Morfill, Gregor; Zimmermann, Julia L

    2012-09-01

    In this study we investigated the sensitivity of Deinococcus radiodurans to contact-free cold atmospheric plasma treatment as part of a project to establish new efficient procedures for disinfection of inanimate surfaces. The Gram-positive D. radiodurans is one of the most resistant microorganisms worldwide. Stationary phases of D. radiodurans were exposed to cold atmospheric plasma for different time intervals or to ultraviolet C (UVC) radiation at dose rates of 0.001-0.0656 J cm⁻², respectively. A methicillin-resistant Staphylococcus aureus strain (MRSA) served as control for Gram-positive bacteria. The surface microdischarge plasma technology was used for generation of cold atmospheric plasma. A plasma discharge was ignited using ambient air. Surprisingly, D. radiodurans was sensitive to the cold atmospheric plasma treatment in the same range as the MRSA strain. Survival of both bacteria decreased with increasing plasma exposure times up to 6 log₁₀ cycles (>99.999 %) within 20 s of plasma treatment. In contrast, UVC radiation of both bacteria demonstrated that D. radiodurans was more resistant to UVC treatment than MRSA. Cold atmospheric plasma seems to be a promising tool for industrial and clinical purposes where time-saving is a critical point to achieve efficient disinfection of inanimate surfaces and where protection from corrosive materials is needed.

  1. Biomedical applications and diagnostics of atmospheric pressure plasma

    Science.gov (United States)

    Petrović, Z. Lj; Puač, N.; Lazović, S.; Maletić, D.; Spasić, K.; Malović, G.

    2012-03-01

    Numerous applications of non-equilibrium (cold, low temperature) plasmas require those plasmas to operate at atmospheric pressure. Achieving non-equilibrium at atmospheric pressure is difficult since the ionization growth is very fast at such a high pressure. High degree of ionization on the other hand enables transfer of energy between electrons and ions and further heating of the background neutral gas through collisions between ions and neutrals. Thus, all schemes to produce non-equilibrium plasmas revolve around some form of control of ionization growth. Diagnostics of atmospheric pressure plasmas is difficult and some of the techniques cannot be employed at all. The difficulties stem mostly from the small size. Optical emission spectroscopy and laser absorption spectroscopy require very high resolution in order to resolve the anatomy of the discharges. Mass analysis is not normally applicable for atmospheric pressure plasmas, but recently systems with triple differential pumping have been developed that allow analysis of plasma chemistry at atmospheric pressures which is essential for numerous applications. Application of such systems is, however, not free from problems. Applications in biomedicine require minimum heating of the ambient air. The gas temperature should not exceed 40 °C to avoid thermal damage to the living tissues. Thus, plasmas should operate at very low powers and power control is essential. We developed unique derivative probes that allow control of power well below 1 W and studied four different sources, including dielectric barrier discharges, plasma needle, atmospheric pressure jet and micro atmospheric pressure jet. The jet operates in plasma bullet regime if proper conditions are met. Finally, we cover results on treatment of bacteria and human cells as well as treatment of plants by plasmas. Localized delivery of active species by plasmas may lead to a number of medical procedures that may also involve removal of bacteria, fungi and

  2. Spray-dried plasma and fresh frozen plasma modulate permeability and inflammation in vitro in vascular endothelial cells.

    Science.gov (United States)

    Wataha, K; Menge, T; Deng, X; Shah, A; Bode, A; Holcomb, J B; Potter, D; Kozar, R; Spinella, P C; Pati, S

    2013-01-01

    After major traumatic injury, patients often require multiple transfusions of fresh frozen plasma (FFP) to correct coagulopathy and to reduce bleeding. A spray-dried plasma (SDP) product has several logistical benefits over FFP use in trauma patients with coagulopathy. These benefits include ease of transport, stability at room temperature, and rapid reconstitution for infusion. Our past work suggests that FFP promotes endothelial stability by inhibiting endothelial permeability. The main goal of this project is to determine if solvent-detergent-treated SDP is equivalent to FFP in inhibiting vascular endothelial cell (EC) permeability and inflammation in vitro. Furthermore, this study aimed to determine if solvent-detergent treatment and spray drying of plasma alters the protective effects of FFP on EC function. The five groups tested in our studies are the following: 1) fresh frozen-thawed plasma (FFP); 2) solvent-detergent-treated FFP; 3) solvent-detergent-treated SDP; 4) lactated Ringer's solution; and 5) Hextend. This study demonstrates that in vitro SDP and FFP equivalently inhibit vascular EC permeability, EC adherens junction breakdown, and endothelial white blood cell binding, an effect that is independent of changes in Vascular Cell Adhesion Molecule 1, Intracellular Adhesion Molecule 1, or E-selectin expression on ECs. Solvent-detergent treatment of FFP does not alter the protective effects of FFP on endothelial cell function in vitro. These data suggest the equivalence of FFP and SDP on modulation of endothelial function and inflammation in vitro. © 2013 American Association of Blood Banks.

  3. In Situ Fabrication of AlN Coating by Reactive Plasma Spraying of Al/AlN Powder

    Directory of Open Access Journals (Sweden)

    Mohammed Shahien

    2011-10-01

    Full Text Available Reactive plasma spraying is a promising technology for the in situ formation of aluminum nitride (AlN coatings. Recently, it became possible to fabricate cubic-AlN-(c-AlN based coatings through reactive plasma spraying of Al powder in an ambient atmosphere. However, it was difficult to fabricate a coating with high AlN content and suitable thickness due to the coalescence of the Al particles. In this study, the influence of using AlN additive (h-AlN to increase the AlN content of the coating and improve the reaction process was investigated. The simple mixing of Al and AlN powders was not suitable for fabricating AlN coatings through reactive plasma spraying. However, it was possible to prepare a homogenously mixed, agglomerated and dispersed Al/AlN mixture (which enabled in-flight interaction between the powder and the surrounding plasma by wet-mixing in a planetary mill. Increasing the AlN content in the mixture prevented coalescence and increased the nitride content gradually. Using 30 to 40 wt% AlN was sufficient to fabricate a thick (more than 200 µm AlN coating with high hardness (approximately 1000 Hv. The AlN additive prevented the coalescence of Al metal and enhanced post-deposition nitriding through N2 plasma irradiation by allowing the nitriding species in the plasma to impinge on a larger Al surface area. Using AlN as a feedstock additive was found to be a suitable method for fabricating AlN coatings by reactive plasma spraying. Moreover, the fabricated coatings consist of hexagonal (h-AlN, c-AlN (rock-salt and zinc-blend phases and certain oxides: aluminum oxynitride (Al5O6N, cubic sphalerite Al23O27N5 (ALON and Al2O3. The zinc-blend c-AlN and ALON phases were attributed to the transformation of the h-AlN feedstock during the reactive plasma spraying. Thus, the zinc-blend c

  4. Atmospheric Plasma Deposition of Diamond-like Carbon Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Ladwig, Angela

    2008-01-23

    There is great demand for thin functional coatings in the semiconductor, optics, electronics, medical, automotive and aerospace industries [1-13]. As fabricated components become smaller and more complex, the properties of the materials’ surface take on greater importance. Thin coatings play a key role in tailoring surfaces to give them the desired hardness, wear resistance, chemical inertness, and electrical characteristics. Diamond-like carbon (DLC) coatings possess an array of desirable properties, including outstanding abrasion and wear resistance, chemical inertness, hardness, a low coefficient of friction and exceptionally high dielectric strength [14-22]. Diamond-like carbon is considered to be an amorphous material, containing a mixture of sp2 and sp3 bonded carbon. Based on the percentage of sp3 carbon and the hydrogen content, four different types of DLC coatings have been identified: tetrahedral carbon (ta-C), hydrogenated amorphous carbon (a-C:H) hard, a-C:H soft, and hydrogenated tetrahedral carbon (ta-C:H) [20,24,25]. Possessing the highest hardness of 80 GPa, ta-C possesses an sp3 carbon content of 80 to 88u%, and no appreciable hydrogen content whereas a-C:H soft possesses a hardness of less than 10 GPa, contains an sp3 carbon content of 60% and a hydrogen content between 30 to 50%. Methods used to deposit DLC coatings include ion beam deposition, cathodic arc spray, pulsed laser ablation, argon ion sputtering, and plasma-enhanced chemical vapor deposition [73-83]. Researchers contend that several advantages exist when depositing DLC coatings in a low-pressure environment. For example, ion beam processes are widely utilized since the ion bombardment is thought to promote denser sp3-bonded carbon networks. Other processes, such as sputtering, are better suited for coating large parts [29,30,44]. However, the deposition of DLC in a vacuum system has several disadvantages, including high equipment cost and restrictions on the size and shape of

  5. Novel Approach in the Use of Plasma Spray: Preparation of Bulk Titanium for Bone Augmentations

    Directory of Open Access Journals (Sweden)

    Michaela Fousova

    2017-08-01

    Full Text Available Thermal plasma spray is a common, well-established technology used in various application fields. Nevertheless, in our work, this technology was employed in a completely new way; for the preparation of bulk titanium. The aim was to produce titanium with properties similar to human bone to be used for bone augmentations. Titanium rods sprayed on a thin substrate wire exerted a porosity of about 15%, which yielded a significant decrease of Young′s modulus to the bone range and provided rugged topography for enhanced biological fixation. For the first verification of the suitability of the selected approach, tests of the mechanical properties in terms of compression, bending, and impact were carried out, the surface was characterized, and its compatibility with bone cells was studied. While preserving a high enough compressive strength of 628 MPa, the elastic modulus reached 11.6 GPa, thus preventing a stress-shielding effect, a generally known problem of implantable metals. U-2 OS and Saos-2 cells derived from bone osteosarcoma grown on the plasma-sprayed surface showed good viability.

  6. Fabrication of gas turbine water-cooled composite nozzle and bucket hardware employing plasma spray process

    Science.gov (United States)

    Schilke, Peter W.; Muth, Myron C.; Schilling, William F.; Rairden, III, John R.

    1983-01-01

    In the method for fabrication of water-cooled composite nozzle and bucket hardware for high temperature gas turbines, a high thermal conductivity copper alloy is applied, employing a high velocity/low pressure (HV/LP) plasma arc spraying process, to an assembly comprising a structural framework of copper alloy or a nickel-based super alloy, or combination of the two, and overlying cooling tubes. The copper alloy is plamsa sprayed to a coating thickness sufficient to completely cover the cooling tubes, and to allow for machining back of the copper alloy to create a smooth surface having a thickness of from 0.010 inch (0.254 mm) to 0.150 inch (3.18 mm) or more. The layer of copper applied by the plasma spraying has no continuous porosity, and advantageously may readily be employed to sustain a pressure differential during hot isostatic pressing (HIP) bonding of the overall structure to enhance bonding by solid state diffusion between the component parts of the structure.

  7. Non-Thermal Sanitation By Atmospheric Pressure Plasma Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC's Non-Thermal Sanitation by Atmospheric Pressure Plasma technology sanitizes fresh fruits and vegetables without the use of consumable chemicals and without...

  8. Plasma Catalytic Extraction of Oxygen from the Martian Atmosphere Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Plasma catalytic techniques are proposed for the extraction of oxygen from the abundant carbon dioxide contained in the Martian atmosphere (95% CO2).. The Phase I...

  9. Plasma Extraction of Oxygen from Martian Atmosphere Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Plasma techniques are proposed for the extraction of oxygen from the abundant carbon dioxide contained in the Martian atmosphere (96 % CO2). In this process, CO2 is...

  10. Non-Thermal Sanitation By Atmospheric Pressure Plasma Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC proposes to develop a non-thermal technology based on atmospheric-pressure (AP) cold plasma to sanitize foods, food packaging materials, and other hardware...

  11. Vacuum Plasma Spray (VPS) Forming of Solar Thermal Propulsion Components Using Refractory Metals

    Science.gov (United States)

    Zimmerman, Frank R.; Hissam, David A.; Gerrish, Harold P.; Davis, William M.

    1999-01-01

    The Thermal Spray Laboratory at NASA's Marshall Space Flight Center has developed and demonstrated a fabrication technique using Vacuum Plasma Spray (VPS) to form structural components from a tungsten/rhenium alloy. The components were assembled into an absorber cavity for a fully-functioning, ground test unit of a solar then-nal propulsion engine. The VPS process deposits refractory metal onto a graphite mandrel of the desired shape. The mandrel acts as a male mold, forming the required contour and dimensions of the inside surface of the deposit. Tungsten and tungsten/25% rhenium were used in the development and production of several absorber cavity components. These materials were selected for their high temperature (greater than 25000 C [greater than 4530 F]) strength. Each absorber cavity comprises 3 coaxial shells with two, double-helical flow passages through which the propellant gas flows. This paper describes the processing techniques, design considerations, and process development associated with forming these engine components.

  12. Microstructure and creep behaviour of plasma sprayed yttria stabilized zirconia thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Soltani, R.; Coyle, T.W.; Mostaghimi [Toronto Univ., ON (Canada)

    2008-07-01

    The purpose of this study was to determine the creep/sintering characteristics of thermally sprayed zirconia coatings and attempt to understand the influence of microstructure on the creep resistance of deposits. The major modification, compared with more typical practice, was employment of powder feedstock with agglomerated sub-micron size particles (Nanox), which is compared to one of the best commercially available powders (HOSP). Thick plasma sprayed coatings were prepared and their physical and mechanical properties were characterized. Creep/sintering experiments were then conducted to investigate the response of the materials when exposed to high temperatures under load. The results showed that it could be possible to correlate the splat thickness to the creep behaviour of the coatings. (orig.)

  13. Field-assisted paper spray mass spectrometry for the quantitative evaluation of imatinib levels in plasma.

    Science.gov (United States)

    D'Aronco, Sara; Calandra, Eleonora; Crotti, Sara; Toffoli, Giuseppe; Marangon, Elena; Posocco, Bianca; Traldi, Pietro; Agostini, Marco

    Drug levels in patients' bloodstreams vary among individuals and consequently therapeutic drug monitoring (TDM) is fundamental to controlling the effective therapeutic range. For TDM purposes, different analytical approaches have been used, mainly based on immunoassay, liquid chromatography- ultraviolet, liquid chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods. More recently a matrix-assisted laser desorption/ionisation method has been proposed for the determination of irinotecan levels in the plasma of subjects under therapy and this method has been cross- validated by comparison with data achieved by LC-MS/MS. However, to reach an effective point-of-care monitoring of plasma drug concentrations, a TDM platform technology for fast, accurate, low-cost assays is required. In this frame, recently the use of paper spray mass spectrometry, which is becoming a popular and widely employed MS method, has been proposed. In this paper we report the results obtained by the development of a paper spray-based method for quantitative analysis in plasma samples of imatinib, a new generation of anticancer drug. Preliminary experiments showed that poor sensitivity, reproducibility and linear response were obtained by the "classical" paper spray set-up. In order to achieve better results, it was thought of interest to operate in presence of a higher and more homogeneous electrical field. For this aim, a stainless steel needle connected with the high voltage power supply was mounted below the paper triangle. Furthermore, in order to obtain valid quantitative data, we analysed the role of the different equilibria participating to the phenomena occurring in paper spray experiments, depending either on instrumental parameters or on the chemical nature of analyte and solvents. A calibration curve was obtained by spiking plasma samples containing different amounts of imatinib (1) with known amounts of deuterated imatinib (1d3) as

  14. Stress residui in W depositato mediante plasma spray: effetto del substrato e delle modalità di processo

    OpenAIRE

    ciambella, L.; Maddaluno, G.; Montanari, R.; Pakhomova, E.

    2015-01-01

    Il tungsteno è un ottimo materiale per ricoprire componenti di prima parete e proteggerli dai danni derivantidall’ esposizione al plasma nei futuri reattori a fusione nucleare. Mediante la tecnica del Plasma Spray sonostati realizzati rivestimenti spessi di tungsteno su diversi substrati tra cui l’acciaio austenitico AISI 316L,l’acciaio martensitico AISI 420 e la lega di rame CuCrZr. La tecnica del Plasma Spray è stata usata per lasemplicità, la possibilità di ricoprire superfi ci estese e di...

  15. Cellular membrane collapse by atmospheric-pressure plasma jet

    Science.gov (United States)

    Kim, Kangil; Jun Ahn, Hak; Lee, Jae-Hyeok; Kim, Jae-Ho; Sik Yang, Sang; Lee, Jong-Soo

    2014-01-01

    Cellular membrane dysfunction caused by air plasma in cancer cells has been studied to exploit atmospheric-pressure plasma jets for cancer therapy. Here, we report that plasma jet treatment of cervical cancer HeLa cells increased electrical conductivity across the cellular lipid membrane and caused simultaneous lipid oxidation and cellular membrane collapse. We made this finding by employing a self-manufactured microelectrode chip. Furthermore, increased roughness of the cellular lipid membrane and sequential collapse of the membrane were observed by atomic force microscopy following plasma jet treatment. These results suggest that the cellular membrane catastrophe occurs via coincident altered electrical conductivity, lipid oxidation, and membrane roughening caused by an atmospheric-pressure plasma jet, possibly resulting in cellular vulnerability to reactive species generated from the plasma as well as cytotoxicity to cancer cells.

  16. Friction and Wear Characteristics of Plasma-Sprayed Self-Lubrication Coating with Clad Powder at Elevated Temperatures up to 800 °C

    Science.gov (United States)

    Huang, Chuanbing; Du, Lingzhong; Zhang, Weigang

    2014-02-01

    NiCr/(Cr3C2-BaF2·CaF2) coating was fabricated by atmospheric plasma spray technology using clad powder. The coating shows low porosity, high microhardness and bonding strength, and it also exhibits good friction reduction and wear resistance at elevated temperatures up to 800 °C which is due to the formation of a kind of continuous BaF2·CaF2 eutectic lubricating film. The excellent mechanical and tribological properties of the coating are partially attributed to the protection of NiCr layer of the composite powders which can decrease oxidation, decarburization of Cr3C2, and ablation of BaF2·CaF2 eutectic during spray and deposition process.

  17. Spacecraft Sterilization Using Non-Equilibrium Atmospheric Pressure Plasma

    Science.gov (United States)

    Cooper, Moogega; Vaze, Nachiket; Anderson, Shawn; Fridman, Gregory; Vasilets, Victor N.; Gutsol, Alexander; Tsapin, Alexander; Fridman, Alexander

    2007-01-01

    As a solution to chemically and thermally destructive sterilization methods currently used for spacecraft, non-equilibrium atmospheric pressure plasmas are used to treat surfaces inoculated with Bacillus subtilis and Deinococcus radiodurans. Evidence of significant morphological changes and reduction in viability due to plasma exposure will be presented, including a 4-log reduction of B. subtilis after 2 minutes of dielectric barrier discharge treatment.

  18. Delayed effects of cold atmospheric plasma on vascular cells

    NARCIS (Netherlands)

    Stoffels, Eva; Roks, Anton J. M.; Deelmm, Leo E.

    2008-01-01

    We investigated the long-term behaviour of vascular cells (endothelial and smooth muscle) after exposure to a cold atmospheric plasma source. The cells were treated through a gas-permeable membrane, in order to simulate intravenous treatment with a gas plasma-filled catheter. Such indirect treatment

  19. 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.

  20. Reactivity zones around an atmospheric pressure plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Birer, Özgür, E-mail: obirer@ku.edu.tr

    2015-11-01

    Highlights: • Polyethylene surfaces were treated with atmospheric pressure cold plasma jet. • The effect of plasma extends beyond the physical jet diameter. • Moieties of –NO, –COO, –CO and –NO{sub 3} as expanding ring patterns were detected. • Active species in the plasma are identified for specific surface moieties. - Abstract: The reactivity zones around an atmospheric pressure plasma jet are revealed by XPS mapping of chemical moieties on a polyethylene surface treated with a 3-mm plasma jet. The area directly hit by the helium plasma jet initially oxidizes and later etches away as the plasma treatment continues. The oxidation initially starts at the center and expands outwards as a ring pattern with different spatial potency. At the end of 10 min plasma jet treatment, distinct ring patterns for –NO, –COO, –CO and –NO{sub 3} species can be detected with respectively increasing diameters. The plasma jet can cause chemical changes at locations several millimeters away from the center. The spatial distribution of oxidized species suggests presence of chemical reactivity zones. Introduction of nitrogen into the helium plasma jet, not only increases the type of nitrogen moieties, but enriches the reactivity zones by generating nitrogen molecular ions within the plasma jet. The complex competing reaction mechanisms among the radicals, ions, metastable atoms and UV photons lead to unusual etching patterns on the surfaces.

  1. Recent Developments in Suspension Plasma Sprayed Titanium Oxide and Hydroxyapatite Coatings

    Science.gov (United States)

    Jaworski, R.; Pawlowski, L.; Pierlot, C.; Roudet, F.; Kozerski, S.; Petit, F.

    2010-01-01

    The paper aims at reviewing of the recent studies related to the development of suspension plasma sprayed TiO2 and Ca5(PO4)3OH (hydroxyapatite, HA) coatings as well as their multilayer composites obtained onto stainless steel, titanium and aluminum substrates. The total thickness of the coatings was in the range 10 to 150 μm. The suspensions on the base of distilled water, ethanol and their mixtures were formulated with the use of fine commercial TiO2 pigment crystallized as rutile and HA milled from commercial spray-dried powder or synthesized from calcium nitrate and ammonium phosphate in an optimized reaction. The powder was crystallized as hydroxyapatite. Pneumatic and peristaltic pump liquid feeders were applied. The injection of suspension to the plasma jet was studied carefully with the use of an atomizer injector or a continuous stream one. The injectors were placed outside or inside of the anode-nozzle of the SG-100 plasma torch. The stream of liquid was tested under angle right or slightly backwards with regard to the torch axis. The sprayed deposits were submitted to the phase analysis by the use of x-ray diffraction. The content of anatase and rutile was calculated in the titanium oxide deposits as well as the content of the decomposition phases in the hydroxyapatite ones. The micro-Raman spectroscopy was used to visualize the area of appearance of some phases. Scratch test enabled to characterize the adhesion of the deposits, their microhardness and friction coefficient. The electric properties including electron emission, impedance spectroscopy, and dielectric properties of some coatings were equally tested.

  2. DISEÑO Y DESARROLLO DE UNA FUENTE CONMUTADA PARA UN SISTEMA DE PLASMA SPRAY

    OpenAIRE

    CHIU ARREOLA, ISRAEL YOSHINORI

    2015-01-01

    Uno de los métodos de pulverización térmica más eficientes que existen es el Plasma Spray. Este sobresale por su versatilidad debido a que puede depositar toda la gama de materiales considerados pulverizables, obteniendo una alta calidad en el recubrimiento. Sin embargo, el alto costo como su nivel de especialización, hacen que la industria en México no invierta en este tipo de técnicas, aun con las bondades que estos sistemas ofrecen. Este tipo de sistemas requieren una fuente de energía que...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-09-15

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

  4. Determination of residual stresses within plasma spray coating using Moire interferometry method

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Yi, E-mail: qaz54809@sina.com [National Key Laboratory for Remanufacturing, Academy of Armored Force Engineering, Beijing, 100072 (China); Naval flying academy of China, Huludao, 125101 (China); Xu Binshi; Wang Haidou; Liu Ming; Lu Yaohui [National Key Laboratory for Remanufacturing, Academy of Armored Force Engineering, Beijing, 100072 (China)

    2011-01-01

    In this paper, residual stresses of the Ni-Cr-B-Si coatings prepared by supersonic plasma spray processing were measured by moire interferometry and X-ray diffraction method. Moire interferometry method was used in measuring the distribution of residual stresses of the Ni-Cr-B-Si coatings alongside the specimen thickness direction, then the distribution of residual stresses both in the substrate and the coating was also analyzed. Experimental results showed that residual stresses in the coating and the substrate are tensile and compressive separately; residual stresses of the coating are diminished with the increase of the distance from the coating surface and almost zero at the coating-substrate interface; the maximum of compressive residual stresses of the substrate are present to the vicinity of the coating-substrate interface. It could be concluded that residual stresses in the specimen would result from the dismatch of thermophysical properties between the coating and substrate during the spray process, and the distribution of residual stresses of the substrate would be influenced by the sandblasting prior to spraying.

  5. Dry Sliding Behavior of Sub-Micrometer-Sized Suspension Plasma Sprayed Ceramic Oxide Coatings

    Science.gov (United States)

    Darut, Geoffrey; Ben-Ettouil, Fadhel; Denoirjean, Alain; Montavon, Ghislain; Ageorges, Hélène; Fauchais, Pierre

    2010-01-01

    Almost half of the energy produced by an automotive engine is dissipated by friction in the cylinders, the clutch, etc. In the context of reduction of the emissions of greenhouse gases (GHGs) to mitigate climate global warming (CGW), reduction of energy losses due to friction is a critical issue. Surface treatments appear in such a context, as never than before, to be able to provide pertinent solutions to improve sliding behavior of mechanical parts. Numerous studies have clearly shown that decreasing the scale of coating structure below the micrometer scale was leading to an improvement of its tribological behavior in terms of friction coefficient and wear rate thanks to improved mechanical properties, the toughness in particular. Suspension Plasma Spraying (SPS) appears as a thermal spray process to be able to manufacture thick (i.e., a few tens of micrometers) coatings exhibiting a sub-micrometer-sized or even a nanometer-sized architecture, while keeping the versatility and flexibility of the thermal spray routes: i.e., the ability to process a wide range of material natures onto a wide range of substrate materials of various geometries. This article aims at studying the tribological behavior of several ceramic oxide composite coatings under dry conditions. The structural scale and the effect of composition are considered in particular.

  6. The Influence of Temperature on Frictional Behavior of Plasma-Sprayed NiAl-Cr2O3 Based Self-Adaptive Nanocomposite Coatings

    Science.gov (United States)

    Ramazani, M.; Ashrafizadeh, F.; Mozaffarinia, R.

    2013-10-01

    Frictional behavior of nano and hybrid-structured NiAl-Cr2O3-Ag-CNT-WS2 adaptive self-lubricant coatings was evaluated at a range of temperatures, from room temperature to 700 °C. For this purpose, hybrid structured (HS) and nanostructured (NS) composite powders with the same nominal compositions were prepared by spray drying and heat treatment techniques. A series of HS and NS coating samples were deposited on steel substrate by an atmospheric plasma spraying process. The tribological behavior of both coatings was studied from room temperature to 700 °C at 100° intervals using a custom designed high temperature wear test machine. Scanning electron microscopy was employed for the evaluation of the composite coatings and worn surfaces. Experimental results indicated that the hybrid coating had inferior tribological properties when compared to the nanostructured coating, showing the attractive frictional behavior on the basis of low friction and high wear resistance; the NS coating possessed a more stable friction coefficient in the temperature range of 25-700 °C against alumina counterface. Microstructural examinations revealed more uniformity in NS plasma-sprayed coatings.

  7. Effect of Gd2O3 on the microstructure and thermal properties of nanostructured thermal barrier coatings fabricated by air plasma spraying

    Directory of Open Access Journals (Sweden)

    Yixiong Wang

    2016-08-01

    Full Text Available The nanostructured 4–8 mol% Gd2O3−4.5 mol% Y2O3-ZrO2 (4–8 mol% GdYSZ coatings were developed by the atmospheric plasma spraying technique. The microstructure and thermal properties of plasma-sprayed 4–8 mol% GdYSZ coatings were investigated. The experimental results indicate that typical microstructure of the as-sprayed coatings were consisted of melted zones, nano-zones, splats, nano-pores, high-volume spheroidal pores and micro-cracks. The porosity of the 4, 6 and 8 mol% GdYSZ coatings was about 9.3%, 11.7% and 13.3%, respectively. It was observed that the addition of gadolinia to the nano-YSZ could significantly reduce the thermal conductivity of nano-YSZ. The thermal conductivity of GdYSZ decreased with increasing Gd2O3 addition. And the reduction in thermal conductivity is mainly attributed to the addition of Gd2O3, which results in the increase in oxygen vacancies, lattice distortion and porosity.

  8. Interfacial microstructures and hardness distributions of vacuum plasma spraying W-coated ODS ferritic steels for fusion plasma facing applications

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Sanghoon, E-mail: shnoh@kaeri.re.kr [Nuclear Materials Division, Korea Atomic Energy Research Institute, Yuseong-gu, Daejeon (Korea, Republic of); Kasada, Ryuta; Kimura, Akihiko [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto (Japan); Nagasaka, Takuya [National Institute for Fusion Science, Toki, Gifu (Japan); Sokolov, Mikhail A. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Kim, Tae Kyu [Nuclear Materials Division, Korea Atomic Energy Research Institute, Yuseong-gu, Daejeon (Korea, Republic of)

    2014-04-15

    In the present study, interfacial microstructures and hardness distributions of W-coated ODS steels as plasma facing structural materials were investigated. A vacuum plasma spraying (VPS) technique was employed to fabricate a W layer on the surface of the ODS ferritic steel substrates. The microstructural observations revealed that the VPS-W has very fine grains aligned toward the spraying direction, and a favorable interface between W and ODS ferritic steels by a mechanical inter-locking without an intermetallic layer. However, crack-type defects were found in VPS-W. Because a brittle inter-diffused layer does not exist at the joint interface, the hardness was gradually distributed in the joint region. After neutron irradiation, irradiation hardening significantly occurred in the VPS-W. However, the hardening of VPS-W was less than that of bulk W irradiated at 773 K. Thus, the VPS is considered to be one of the promising ways to join dissimilar materials between W and ODS steels, which can avoid the formation of an interfacial intermetallic layer and create favorable irradiation hardening resistance on the W coated layer.

  9. Surface Modification of Nonwoven fabrics by Atmospheric Brush Plasma

    Science.gov (United States)

    Oksuz, Lutfi; Uygun, Emre; Bozduman, Ferhat; Yurdabak Karaca, Gozde; Asan, Orkun Nuri; Uygun Oksuz, Aysegul

    2017-10-01

    Polypropylene nonwoven fabrics (PPNF) are used in disposable absorbent articles, such as diapers, feminine care products, wipes. PPNF need to be wettable by water or aqueous-based liquid. Plasma surface treatment/modification has turned out to be a well-accepted method since it offers superior surface property enhancement than other chemical methods. The cold plasma brush can most efficiently use the discharge power as well as the plasma gas for material and surface treatment. The very low power consumption of such an atmospheric argon plasma brush provides many unique advantages in practical application. The purpose of this study was to reveal the effectiveness of non-thermal atmospheric plasma brush in surface wettability and modification of two different nonwoven surfaces.

  10. Erosion Performance of Gadolinium Zirconate-Based Thermal Barrier Coatings Processed by Suspension Plasma Spray

    Science.gov (United States)

    Mahade, Satyapal; Curry, Nicholas; Björklund, Stefan; Markocsan, Nicolaie; Nylén, Per; Vaßen, Robert

    2017-01-01

    7-8 wt.% Yttria-stabilized zirconia (YSZ) is the standard thermal barrier coating (TBC) material used by the gas turbines industry due to its excellent thermal and thermo-mechanical properties up to 1200 °C. The need for improvement in gas turbine efficiency has led to an increase in the turbine inlet gas temperature. However, above 1200 °C, YSZ has issues such as poor sintering resistance, poor phase stability and susceptibility to calcium magnesium alumino silicates (CMAS) degradation. Gadolinium zirconate (GZ) is considered as one of the promising top coat candidates for TBC applications at high temperatures (>1200 °C) due to its low thermal conductivity, good sintering resistance and CMAS attack resistance. Single-layer 8YSZ, double-layer GZ/YSZ and triple-layer GZdense/GZ/YSZ TBCs were deposited by suspension plasma spray (SPS) process. Microstructural analysis was carried out by scanning electron microscopy (SEM). A columnar microstructure was observed in the single-, double- and triple-layer TBCs. Phase analysis of the as-sprayed TBCs was carried out using XRD (x-ray diffraction) where a tetragonal prime phase of zirconia in the single-layer YSZ TBC and a cubic defect fluorite phase of GZ in the double and triple-layer TBCs was observed. Porosity measurements of the as-sprayed TBCs were made by water intrusion method and image analysis method. The as-sprayed GZ-based multi-layered TBCs were subjected to erosion test at room temperature, and their erosion resistance was compared with single-layer 8YSZ. It was shown that the erosion resistance of 8YSZ single-layer TBC was higher than GZ-based multi-layered TBCs. Among the multi-layered TBCs, triple-layer TBC was slightly better than double layer in terms of erosion resistance. The eroded TBCs were cold-mounted and analyzed by SEM.

  11. Parameters of atmospheric plasmas produced by electrosurgical devices

    Science.gov (United States)

    Keidar, Michael; Shashurin, Alexey; Canady, Jerome

    2013-10-01

    Electrosurgical systems are extensively utilized in general surgery, surgical oncology, plastic and reconstructive surgery etc. In this work we study plasma parameters created by electrosurgical system SS-200E/Argon 2 of US Medical Innovations. The maximal length of the discharge plasma column at which the discharge can be sustained was determined as function of discharge power and argon flow rate. Electrical parameters including discharge current and voltage were measured. Recently proposed Rayleigh microwave scattering method for temporally resolved density measurements of small-size atmospheric plasmas was utilized. Simultaneously, evolution of plasma column was observed using intensified charge-coupled device (ICCD) camera.

  12. Preparation of Lanthanum Zirconate Coatings by the Solution Precursor Plasma Spray

    Science.gov (United States)

    Wang, W. Z.; Coyle, T.; Zhao, D.

    2014-06-01

    Solution precursor plasma spray (SPPS) can synthesize powders and deposit the coatings synchronously. The lanthanum zirconate coatings are deposited by SPPS in the present study, and the dense coating can be obtained through changing the precursor solution. The addition of urea can change the heat exchange process for some precursor mixtures. However, almost no effect can be found on the microstructure of powder and coating by the addition of urea. The extra heat energy caused by the addition of urea is so small, as compared with the heat input by the present plasma jet, so that the heating effect can be ignored. The porosity of coatings increase when the LaCl3·7H2O instead of La(NO3)3·6H2O reacts with Zr(CH3CO2)4.

  13. MicroScale - Atmospheric Pressure Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Sankaran, Mohan [Case Western Reserve University

    2012-01-25

    Low-temperature plasmas play an essential role in the manufacturing of integrated circuits which are ubiquitous in modern society. In recent years, these top-down approaches to materials processing have reached a physical limit. As a result, alternative approaches to materials processing are being developed that will allow the fabrication of nanoscale materials from the bottom up. The aim of our research is to develop a new class of plasmas, termed “microplasmas” for nanomaterials synthesis. Microplasmas are a special class of plasmas formed in geometries where at least one dimension is less than 1 mm. Plasma confinement leads to several unique properties including high-pressure stability and non-equilibrium that make microplasams suitable for nanomaterials synthesis. Vapor-phase precursors can be dissociated to homogeneously nucleate nanometer-sized metal and alloyed nanoparticles. Alternatively, metal salts dispersed in liquids or polymer films can be electrochemically reduced to form metal nanoparticles. In this talk, I will discuss these topics in detail, highlighting the advantages of microplasma-based systems for the synthesis of well-defined nanomaterials.

  14. Characterization of thick plasma spray tungsten coating on ferritic/martensitic steel F82H for high heat flux armor

    Science.gov (United States)

    Yahiro, Y.; Mitsuhara, M.; Tokunakga, K.; Yoshida, N.; Hirai, T.; Ezato, K.; Suzuki, S.; Akiba, M.; Nakashima, H.

    2009-04-01

    Two types of plasma spray tungsten coatings on ferritic/martensitic steel F82H made by vacuum plasma spray technique (VPS) and air plasma spray technique (APS) were examined in this study to evaluate the possibility as plasma-facing armor. The VPS-W/F82H showed superior properties. The porosity of the VPS-W coatings was about 0.6% and most of the pores were smaller than 1-2 μm and joining of W/F82H and W/W was fairly good. Thermal load tests indicated high potential of this coating as plasma-facing armor under thermal loading. In case of APS-W/F82H, however, porosity was 6% and thermal load properties were much worse than VPS-W/F82H. It is likely that surface oxidation during plasma spray process reduced joining properties. Remarkably, both coatings created soft ferrite interlayer after proper heat treatments probably due to high residual stress at the interfaces after the production. This indicates the potential function of the interlayer as stress relieve and possible high performance of such coating component under thermal loads.

  15. Effect of aluminum phosphate additions on composition of three-component plasma-sprayed solid lubricant

    Science.gov (United States)

    Jacobson, T. P.; Young, S. G.

    1982-01-01

    Image analysis (IA) and electron microprobe X-ray analysis (EMXA) were used to characterize a plasma-sprayed, self-lubricating coating, NASA LUBE PS106, specified by weight percent as 35NiCr-35Ag-30CaF2. To minimize segregation of the powder mixture during the plasma-spraying procedure, monoaluminum phosphate was added to form agglomerate particles. Three concentrations of AlPO4 were added to the mixtures: 1.25, 2.5, and 6.25 percent by weight. Analysis showed that 1.25 wt% AlPO4 yielded a CaF2 deficiency, 2.5 wt% kept the coating closest to specification, and 6.25 wt% yielded excess CaF2 as well as more impurities and voids and a deficiency in silver. Photomicrographs and X-ray maps are presented. The methods of IA and EMXA complement each other, and the reasonable agreement in the results increases the confidence in determining the coating composition.

  16. INTERACTION STUDIES OF CERAMIC VACUUM PLASMA SPRAYING FOR THE MELTING CRUCIBLE MATERIALS

    Directory of Open Access Journals (Sweden)

    JONG HWAN KIM

    2013-10-01

    Full Text Available Candidate coating materials for re-usable metallic nuclear fuel crucibles, TaC, TiC, ZrC, ZrO2, and Y2O3, were plasma-sprayed onto a niobium substrate. The microstructure of the plasma-sprayed coatings and thermal cycling behavior were characterized, and U-Zr melt interaction studies were carried out. The TaC and Y2O3 coating layers had a uniform thickness, and high density with only a few small closed pores showing good consolidation, while the ZrC, TiC, and ZrO2 coatings were not well consolidated with a considerable amount of porosity. Thermal cycling tests showed that the adhesion of the TiC, ZrC, and ZrO2 coating layers with niobium was relatively weak compared to the TaC and Y2O3 coatings. The TaC and Y2O3 coatings had better cycling characteristics with no interconnected cracks. In the interaction studies, ZrC and ZrO2 coated rods showed significant degradations after exposure to U-10 wt.% Zr melt at 1600°C for 15 min., but TaC, TiC, and Y2O3 coatings showed good compatibility with U-Zr melt.

  17. Stimulation of wound healing by helium atmospheric pressure plasma treatment

    Science.gov (United States)

    Vasile Nastuta, Andrei; Topala, Ionut; Grigoras, Constantin; Pohoata, Valentin; Popa, Gheorghe

    2011-03-01

    New experiments using atmospheric pressure plasma have found large application in treatment of living cells or tissues, wound healing, cancerous cell apoptosis, blood coagulation on wounds, bone tissue modification, sterilization and decontamination. In this study an atmospheric pressure plasma jet generated using a cylindrical dielectric-barrier discharge was applied for treatment of burned wounds on Wistar rats' skin. The low temperature plasma jet works in helium and is driven by high voltage pulses. Oxygen and nitrogen based impurities are identified in the jet by emission spectroscopy. This paper analyses the natural epithelization of the rats' skin wounds and two methods of assisted epithelization, a classical one using polyurethane wound dressing and a new one using daily atmospheric pressure plasma treatment of wounds. Systemic and local medical data, such as haematological, biochemical and histological parameters, were monitored during entire period of study. Increased oxidative stress was observed for plasma treated wound. This result can be related to the presence in the plasma volume of active species, such as O and OH radicals. Both methods, wound dressing and plasma-assisted epithelization, provided positive medical results related to the recovery process of burned wounds. The dynamics of the skin regeneration process was modified: the epidermis re-epitelization was accelerated, while the recovery of superficial dermis was slowed down.

  18. Stimulation of wound healing by helium atmospheric pressure plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Nastuta, Andrei Vasile; Topala, Ionut; Pohoata, Valentin; Popa, Gheorghe [Faculty of Physics, Alexandru Ioan Cuza University, Bd. Carol No. 11, 700506, Iasi (Romania); Grigoras, Constantin, E-mail: andrei.nastuta@uaic.ro [Physiopathology Department, Grigore T. Popa University of Medicine and Pharmacy, 700115, Iasi (Romania)

    2011-03-16

    New experiments using atmospheric pressure plasma have found large application in treatment of living cells or tissues, wound healing, cancerous cell apoptosis, blood coagulation on wounds, bone tissue modification, sterilization and decontamination. In this study an atmospheric pressure plasma jet generated using a cylindrical dielectric-barrier discharge was applied for treatment of burned wounds on Wistar rats' skin. The low temperature plasma jet works in helium and is driven by high voltage pulses. Oxygen and nitrogen based impurities are identified in the jet by emission spectroscopy. This paper analyses the natural epithelization of the rats' skin wounds and two methods of assisted epithelization, a classical one using polyurethane wound dressing and a new one using daily atmospheric pressure plasma treatment of wounds. Systemic and local medical data, such as haematological, biochemical and histological parameters, were monitored during entire period of study. Increased oxidative stress was observed for plasma treated wound. This result can be related to the presence in the plasma volume of active species, such as O and OH radicals. Both methods, wound dressing and plasma-assisted epithelization, provided positive medical results related to the recovery process of burned wounds. The dynamics of the skin regeneration process was modified: the epidermis re-epitelization was accelerated, while the recovery of superficial dermis was slowed down.

  19. Free-floating atmospheric pressure ball plasmas

    Science.gov (United States)

    Wurden, G. A.; Ticos, C.; Wang, Z.; Wurden, C. J. V.

    2007-11-01

    A long-lived (0.3 second, 10-20 cm diameter) ball plasma floating in the air above a water surface has been formed and studied in the laboratory. A 0.4 - 1 mF capacitor is charged to 4-5 kV, and subsequently discharged (30-60 Amps, 20-50 msec duration) into central copper cathode held fixed just below the surface of a bucket of water (with a weak solution of various salts in distilled water, such as CuSO4 or CuCl2, LiCl or NaCl). An underwater ring anode completes the circuit. A bubble of hot vapor from the water surface rises up in the first few milliseconds, and changes from a mushroom cloud with stalk, to a detached quasi-spherical object, finally evolving into a vortex ring. The plasma consists of ionized water vapor, with positive salts and OH- radicals, as well as molecular species, and it completely excludes nitrogen or oxygen from the rising plasma structure. A fine boundary layer is visible in orange, in contrast to a green ball interior when using Cu/CuSO4, and filamentary structures are visible at late times. Finally, a whisp of smoke ring is observed as a residue. A variety of visible and infrared imaging (both video and still cameras) are used, along with 200-800 nm time & space resolved spectroscopy, to identify features of this laboratory analog to ball lightning. Possible applications include a windowless ball- plasma powered pulsed copper vapor laser operating at 510 nm.

  20. Sterilization of Turmeric by Atmospheric Pressure Dielectric Barrier Discharge Plasma

    Science.gov (United States)

    Setareh, Salarieh; Davoud, Dorranian

    2013-11-01

    In this study atmospheric pressure dielectric barrier discharge (DBD) plasma has been employed for sterilizing dry turmeric powders. A 6 kV, 6 kHz frequency generator was used to generate plasma with Ar, Ar/O2, He, and He/O2 gases between the 5 mm gap of two quartz covered electrodes. The complete sterilization time of samples due to plasma treatment was measured. The most important contaminant of turmeric is bacillus subtilis. The results show that the shortest sterilization time of 15 min is achieved by exposing the samples to Ar/O2 plasma. Survival curves of samples are exponential functions of time and the addition of oxygen to plasma leads to a significant increase of the absolute value of time constant of the curves. Magnitudes of protein and DNA in treated samples were increased to a similar value for all samples. Taste, color, and solubility of samples were not changed after the plasma treatment.

  1. Generation of nano roughness on fibrous materials by atmospheric plasma

    Science.gov (United States)

    Kulyk, I.; Scapinello, M.; Stefan, M.

    2012-12-01

    Atmospheric plasma technology finds novel applications in textile industry. It eliminates the usage of water and of hazard liquid chemicals, making production much more eco-friendly and economically convenient. Due to chemical effects of atmospheric plasma, it permits to optimize dyeing and laminating affinity of fabrics, as well as anti-microbial treatments. Other important applications such as increase of mechanical resistance of fiber sleeves and of yarns, anti-pilling properties of fabrics and anti-shrinking property of wool fabrics were studied in this work. These results could be attributed to the generation of nano roughness on fibers surface by atmospheric plasma. Nano roughness generation is extensively studied at different conditions. Alternative explanations for the important practical results on textile materials and discussed.

  2. Ultra-fast quantitation of voriconazole in human plasma by coated blade spray mass spectrometry.

    Science.gov (United States)

    Tascon, Marcos; Gómez-Ríos, Germán Augusto; Reyes-Garcés, Nathaly; Poole, Justen; Boyacı, Ezel; Pawliszyn, Janusz

    2017-09-10

    Voriconazole is a triazole broad-spectrum antifungal medication often used to treat fungal infections caused by Aspergillus and Fusarium species. One of the main challenges associated with the implementation of this medication is its narrow therapeutic concentration range, demonstrating toxicity at concentrations above 6μg/mL and limited efficacy at concentrations below 2μg/mL. As a result, methodologies which permit the rapid and accurate quantitation of voriconazole in patients are highly desirable. In this work two different approaches based on coated blade spray directly coupled to mass spectrometry (CBS-MS) are introduced; each enabling the quantitation of voriconazole in plasma samples with a simple and fast sample preparation and no chromatographic step. The first approach involves a rapid extraction (1min) of the target analyte from 300μL of human plasma using conventional laboratory vessels (e.g. vial, 96-well plate). Alternatively, the second strategy consists of a 2min extraction from a plasma droplet (10μL) placed on the coated area of the blade. Both procedures were successfully validated and good linearity (R 2 ≥0.998), accuracy (91-122%) and precision (voriconazole in human plasma samples. Indeed, the proposed methodology can be easily used either for routine drug monitoring or for in vitro pharmacokinetic studies in applications where very small sample volumes are available and great temporal resolution is needed. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Comparison of solidity and fractal dimension of plasma sprayed splat with different spreading morphologies

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shu-ying; Ma, Guo-zheng, E-mail: magz0209@163.com; Wang, Hai-dou, E-mail: wanghaidou@aliyun.com.cn; He, Peng-fei; Liu, Ming; Wang, Hai-jun; Xu, Bin-shi

    2017-07-01

    Highlights: • The solidification mechanism of the plasma sprayed droplets deposited on substrate preheated with different temperature was discussed. • The solidified morphology of individual splat was detected by image analysis method. • The fractal dimension, solidity, area and perimeter, were employed to characterize the morphology of the splat. • The typical solidification modes of Fe-based alloy droplet could be divided into three types, namely, flower-like splat, splashed splat and disk-like splat, which may be attributed the differences of solidification rate of the droplets and adsorption on the substrates. - Abstract: The paper deals with the quantitative characterization of spreading morphologies of plasma sprayed Fe-based alloy droplets deposited on mirror polished steels with different preheated temperature. The plasma torch was utilized as heat producer. The influence of substrate temperature on the solidification mechanism of molten droplets was investigated. The image analysis method (IMA) was employed to identify single splat from the field emission scanning electron microscope (FE-SEM) morphology. The result shows that the substrate preheated temperature has a significant effect on the flattening behavior of molten droplets. With the increment of substrate temperature, the solidification mode of splat changes from flower-like and splashed splat to disk-like splat due to the modification of wettability and cooling velocity between molten droplet and substrate. Compared with area and perimeter, both fractal dimension (FD) and solidity could separately detect the solidification mode of splat to a certain extent, while the FD seems to be more excellent in characterizing irregular morphology of splat in contrast with solidity. However, the combination of FD and solidity is more efficient in classifying solidification mode of splat.

  4. Nanostructured bioactive glass-ceramic coatings deposited by the liquid precursor plasma spraying process

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Yanfeng; Song Lei; Liu Xiaoguang; Huang Yi; Huang Tao; Wu Yao; Chen Jiyong [National Engineering Research Center for Biomaterials, Sichuan University, 29 Wangjiang Road Chengdu, Sichuan 610064 (China); Wu Fang, E-mail: fwu@scu.edu.cn [National Engineering Research Center for Biomaterials, Sichuan University, 29 Wangjiang Road Chengdu, Sichuan 610064 (China)

    2011-01-01

    Bioactive glass-ceramic coatings have great potential in dental and orthopedic medical implant applications, due to its excellent bioactivity, biocompatibility and osteoinductivity. However, most of the coating preparation techniques either produce only thin thickness coatings or require tedious preparation steps. In this study, a new attempt was made to deposit bioactive glass-ceramic coatings on titanium substrates by the liquid precursor plasma spraying (LPPS) process. Tetraethyl orthosilicate, triethyl phosphate, calcium nitrate and sodium nitrate solutions were mixed together to form a suspension after hydrolysis, and the liquid suspension was used as the feedstock for plasma spraying of P{sub 2}O{sub 5}-Na{sub 2}O-CaO-SiO{sub 2} bioactive glass-ceramic coatings. The in vitro bioactivities of the as-deposited coatings were evaluated by soaking the samples in simulated body fluid (SBF) for 4 h, 1, 2, 4, 7, 14, and 21 days, respectively. The as-deposited coating and its microstructure evolution behavior under SBF soaking were systematically analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma (ICP), and Fourier transform infrared (FTIR) spectroscopy. The results showed that P{sub 2}O{sub 5}-Na{sub 2}O-CaO-SiO{sub 2} bioactive glass-ceramic coatings with nanostructure had been successfully synthesized by the LPPS technique and the synthesized coatings showed quick formation of a nanostructured HCA layer after being soaked in SBF. Overall, our results indicate that the LPPS process is an effective and simple method to synthesize nanostructured bioactive glass-ceramic coatings with good in vitro bioactivity.

  5. Bulge Testing and Interface Fracture Characterization of Plasma-Sprayed and HIP Bonded Zr Coatings on U-Mo

    Science.gov (United States)

    Hollis, K.; Liu, C.; Leckie, R.; Lovato, M.

    2015-01-01

    Bulge testing using a pressurized fluid to fracture the interface between bonded material layers along with three-dimensional digital image correlation to measure the sample distortion caused by pressurized fluid was applied to plasma-sprayed coatings. The initiation fracture toughness associated with the bonded materials was measured during the testing. The bulge testing of the uranium-molybdenum alloy plasma sprayed with zirconium and clad in aluminum is presented. The initiation fracture toughness was observed to increase with the increasing cathodic arc-cleaning current and the use of alternating polarity transferred arc current. This dependence was linked to the interface composition of oxide and mixed metal phases along with the interface temperature during spray deposition.

  6. Improvements in Microstructure and Wear Resistance of Plasma-Sprayed Fe-Based Amorphous Coating by Laser-Remelting

    Science.gov (United States)

    Jiang, Chaoping; Chen, Hong; Wang, Gui; Chen, Yongnan; Xing, Yazhe; Zhang, Chunhua; Dargusch, Matthew

    2017-04-01

    Amorphous coating technology is an attractive way of taking advantage of the superior properties of amorphous alloys for structural applications. However, the limited bonds between splats within the plasma-sprayed coatings result in a typically lamellar and porous coating structure. To overcome these limitations, the as-sprayed coating was treated by a laser-remelting process. The microstructure and phase composition of two coatings were analyzed using scanning electron microscopy with energy-dispersive spectroscopy, transmission electron microscopy, and x-ray diffraction. The wear resistance of the plasma-sprayed coating and laser-remelted coating was studied comparatively using a pin-on-disc wear test under dry friction conditions. It was revealed that the laser-remelted coating exhibited better wear resistance because of its defect-free and amorphous-nanocrystalline composited structure.

  7. Phase stability and biological property evaluation of plasma sprayed hydroxyapatite coatings for orthopedic and dental applications.

    Science.gov (United States)

    Vahabzadeh, Sahar; Roy, Mangal; Bandyopadhyay, Amit; Bose, Susmita

    2015-04-01

    In this work we have investigated the effects of strontium (Sr) dopant on in vitro protein release kinetics and in vivo osteogenic properties of plasma sprayed hydroxyapatite (HA) coatings, along with their dissolution behavior. Plasma sprayed HA coatings are widely used in load-bearing implants. Apart from osseointegration, the new generation of HA coating is expected to deliver biomolecules and/or drugs that can induce osteoinduction. This paper reports the preparation of crystalline and amorphous HA coatings on commercially pure titanium (Cp-Ti) using inductively coupled radio frequency (RF) plasma spray, and their stability at different solution pH. Coatings prepared at 110 mm working distance from the nozzle showed an average Ca ion release of 18 and 90 ppm in neutral and acidic environments, respectively. Decreasing the working distance to 90 mm resulted in the formation of a coating with less crystalline HA and phases with higher solubility products, and consequently higher dissolution over 32 days. A 92% release of a model protein bovine serum albumin (BSA) in phosphate buffer with pH of 7.4 was measured for Sr-doped HA (Sr-HA) coating, while only a 72% release could be measured for pure HA coating. Distortion of BSA during adsorption on coatings revealed a strong interaction between the protein and the coating, with an increase in α-helix content. Osteoid formation was found on Sr-HA implants as early as 7 weeks post implantation compared to HA coated and uncoated Ti implants. After 12 weeks post implantation, osteoid new bone was formed on HA implants; whereas, bone mineralization started on Sr-HA samples. While no osteoid was formed on bare Ti surfaces, bone was completely mineralized on HA and Sr-HA coatings after 16 weeks post implantation. Our results show that both phase stability and chemistry can have a significant influence toward in vitro and in vivo response of HA coatings on Ti implants. Copyright © 2015 Acta Materialia Inc. Published by

  8. Radiation Spectral Analysis and Particle Temperature/Velocity Measurement in Plasma Spray with One-Color Camera

    Science.gov (United States)

    Wang, B. H.; Li, B. Q.; Yang, Huan; Bai, Y.

    2017-10-01

    A color camera optical diagnostic imaging system has been developed for the measurement of temperature and velocity of individual in-flight particles in thermal plasma spray, based on the principle of particle streak velocimetry and two-color thermometry. Radiation spectral analysis of the characteristic behavior of a particle-laden plasma plume was performed to identify an optimal spectral range for accurate temperature measurements over which the powder particles and the interfering thermal plasma gas are discernable. Calibration of the thermal imaging system was carried out using a blackbody furnace with uncertainties less than 1.8%. Extensive experimental measurements were taken with the optical imaging system to obtain the temperature and velocity distributions of YSZ particles in practical plasma spraying applications. The uncertainties of the measured temperature and velocity with a color camera system mostly fluctuate around ±10% in comparison with data obtained from a commercially available measuring system.

  9. Improvement of the Quality and the Shelf Life of the High Oxygen Modified Atmosphere Packaged Veal by Superficial Spraying with Dihydroquercetin Solution

    Directory of Open Access Journals (Sweden)

    Stefan Georgiev Dragoev

    2014-01-01

    Full Text Available The improvement of quality and the shelf life of veal by combination of 80%O2/20%CO2 modified atmosphere packaging and superficial spraying with 0.02% dihydroquercetin solutions was studied. The control samples C, air packaged only, D, air packaged sprayed by 0.02% dihydroquercetin solution, MAP, modified atmosphere packaging only, BMAP, modified atmosphere packaging sprayed by 0.02% butylated hydroxytoluene solution, and DMAP, modified atmosphere packaging sprayed by 0.02% dihydroquercetin solution, were measured. The best results were obtained in modified atmosphere packaging sprayed by 0.02% dihydroquercetin solution. Comparisons with control samples were expressed as reduction in acid value with 27.72%, peroxide value with 64.74%, 2-thiobarbituric acid reactive substances (TBARS with 65.71%, and the pH with 6.18%. The acid and peroxide values, TBARS, and pH were decreased linearly in response when applying the combination of 80%O2/20%CO2 modified atmosphere packaging and superficial spraying with 0.02% dihydroquercetin solutions (P0.05. According to results obtained it was concluded that 80%O2/20%CO2 modified atmosphere packaged veal stored at 0±0.5°C after 0.02% dihydroquercetin solution treatment can preserve its quality and shelf life to 15 d postmortem.

  10. Oxygen Plasma Treatment of Rubber Surface by the Atmospheric Pressure Cold Plasma Torch

    DEFF Research Database (Denmark)

    Lee, Bong-ju; Kusano, Yukihiro; Kato, Nobuko

    1997-01-01

    A new application of the atmospheric cold plasma torch has been investigated. Namely, the surface treatment of an air-exposed vulcanized rubber compound. The effect of plasma treatment was evaluated by the bondability of the treated rubber compound with another rubber compound using a polyurethane...

  11. Characterization of gas tunnel type plasma sprayed hydroxyapatite-nanostructure titania composite coatings

    Science.gov (United States)

    Yugeswaran, S.; Kobayashi, A.; Ucisik, A. Hikmet; Subramanian, B.

    2015-08-01

    Hydroxyapatite (HA) can be coated onto metal implants as a ceramic biocompatible coating to bridge the growth between implants and human tissue. Meanwhile many efforts have been made to improve the mechanical properties of the HA coatings without affecting its bioactivity. In the present study, nanostructure titania (TiO2) was mixed with HA powder and HA-nanostructure TiO2 composite coatings were produced by gas tunnel type plasma spraying torch under optimized spraying conditions. For this purpose, composition of 10 wt% TiO2 + 90 wt% HA, 20 wt% TiO2 + 80 wt% HA and 30 wt% TiO2 + 70 wt% HA were selected as the feedstock materials. The phase, microstructure and mechanical properties of the coatings were characterized. The obtained results validated that the increase in weight percentage of nanostructure TiO2 in HA coating significantly increased the microhardness, adhesive strength and wear resistance of the coatings. Analysis of the in vitro bioactivity and cytocompatibility of the coatings were done using conventional simulated body fluid (c-SBF) solution and cultured green fluorescent protein (GFP) labeled marrow stromal cells (MSCs) respectively. The bioactivity results revealed that the composite coating has bio-active surface with good cytocompatibility.

  12. Dielectric and electrochemical properties through-thickness mapping on extremely thick plasma sprayed TiO2

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Sedláček, J.; Pala, Zdeněk

    2016-01-01

    Roč. 42, č. 6 (2016), s. 7183-7191 ISSN 0272-8842 Institutional support: RVO:61389021 Keywords : Electrical properties * TiO2 * Plasma spraying * Annealing * Microstructure Subject RIV: JH - Ceramics , Fire-Resistant Materials and Glass Impact factor: 2.986, year: 2016 http://www.sciencedirect.com/science/article/pii/S0272884216001395

  13. IMPROVEMENT OF MECHANICAL PROPERTIES OF ALUMINA AND ZIRCONIA PLASMA SPRAYED COATINGS INDUCED BY LASER POST-TREATMENT

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Kraus, L.; Tuominen, J.; Vuoristo, P.; Chráska, Pavel

    2007-01-01

    Roč. 51, č. 4 (2007), s. 181-189 ISSN 0862-5468 R&D Projects: GA AV ČR 1QS200430560 Institutional research plan: CEZ:AV0Z20430508 Keywords : Alumina * plasma spraying * wear resistance * slurry abrasion Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.488, year: 2007

  14. A systematic review on the long-term success of calcium phosphate plasma-spray-coated dental implants

    NARCIS (Netherlands)

    Oirschot, B.A.J.A. van; Bronkhorst, E.M.; Beucken, J.J.J.P van den; Meijer, G.J.; Jansen, J.A.; Junker, R.

    2016-01-01

    The objectives of the current review were (1) to systematically appraise, and (2) to evaluate long-term success data of calcium phosphate (CaP) plasma-spray-coated dental implants in clinical trials with at least 5 years of follow-up. To describe the long-term efficacy of functional implants, the

  15. Surface Modification by Atmospheric Pressure Plasma for Improved Bonding

    Science.gov (United States)

    Williams, Thomas Scott

    An atmospheric pressure plasma source operating at temperatures below 150?C and fed with 1.0-3.0 volume% oxygen in helium was used to activate the surfaces of the native oxide on silicon, carbon-fiber reinforced epoxy composite, stainless steel type 410, and aluminum alloy 2024. Helium and oxygen were passed through the plasma source, whereby ionization occurred and ˜10 16 cm-3 oxygen atoms, ˜1015 cm -3 ozone molecules and ˜1016 cm-3 metastable oxygen molecules (O21Deltag) were generated. The plasma afterglow was directed onto the substrate material located 4 mm downstream. Surface properties of the plasma treated materials have been investigated using water contact angle (WCA), atomic force microscopy (AFM), infrared spectroscopy (IR), and x-ray photoelectron spectroscopy (XPS). The work presented herein establishes atmospheric-pressure plasma as a surface preparation technique that is well suited for surface activation and enhanced adhesive bond strength in a variety of materials. Atmospheric plasma activation presents an environmentally friendly alternative to wet chemical and abrasive methods of surface preparation. Attenuated total internal reflection infrared spectroscopy was used to study the aging mechanism of the native oxide on silicon. During storage at ambient conditions, the water contact angle of a clean surface increased from peel ply. After oxygen plasma activation and joining the materials together with epoxy, one observes 100% cohesive failure within the cured film adhesive. Depending on the material, the lap shear strength can be increased several fold over that achieved by either solvent wiping or abrasion. The trends in adhesion with plasma exposure time do not correlate well with surface wetting or roughness; instead they correlate with the fraction of the polymer surface sites that are converted into carboxylic acid groups.

  16. Ultrasound enhanced plasma surface modification at atmospheric pressure

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Singh, Shailendra Vikram; Norrman, Kion

    2012-01-01

    Efficiency of atmospheric pressure plasma treatment can be highly enhanced by simultaneous high power ultrasonic irradiation onto the treating surface. It is because ultrasonic waves with a sound pressure level (SPL) above ∼140 dB can reduce the thickness of a boundary gas layer between the plasm...

  17. Generation of uniform atmospheric pressure argon glow plasma by ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 80; Issue 3. Generation of uniform atmospheric pressure argon glow plasma by dielectric barrier discharge. Raju Bhai Tyata Deepak Prasad Subedi Rajendra Shrestha Chiow San Wong. Research Articles Volume 80 Issue 3 March 2013 pp 507-517 ...

  18. Microstructure evolution and mechanical properties of TiCN-Cr nano/micro composite coatings prepared by reactive plasma spraying

    Science.gov (United States)

    Zhang, Fanyong; He, Jining; Chen, Kai; Qin, Yanfang; Li, Chao; Yin, Fuxing

    2018-01-01

    Nanostructured TiCN based composite coatings with various Cr content were prepared by reactive plasma spray (RPS) from mixed powder (Ti-graphite + Cr) under nitrogen atmosphere. Results showed that composite coatings consisted mainly of TiC0.7N0.3 phase and residual metal Cr. Metal Cr plates were homogeneously embedded in TiCN matrix with good interface bond. The TiCN-Cr composite coatings exhibited lower porosity than TiCN coatings, but increasing porosity with excess Cr addition (30 wt.%). The TiCN-20 wt.% Cr coating showed the highest hardness (1309 HV0.2) among composite coatings, slight lower than the TiCN matrix coating (1526 HV0.2). Compared with the TiCN matrix coating, the TiCN-Cr composite coatings showed higher variability in surface microhardness distribution. The TiCN-Cr composite coatings showed slight higher friction coefficients (0.4-0.6) than TiCN matrix coating (0.35). The wear resistance of TiCN-Cr composite coatings was improved with less mass loss compared with TiCN coating under the test load of 400 N. The TiCN-Cr composite coatings with high Cr content showed the mixture of abrasive and adhesive wear.

  19. Cold atmospheric plasma sterilization: from bacteria to biomolecules

    Science.gov (United States)

    Kong, Michael

    2009-10-01

    Although ionized gases have been known to have biological effects for more than 100 years, their impact on the practice in healthcare service became very significant only recently. Today, plasma-based surgical tools are used for tissue reduction and blood coagulation as surgical procedures. Most significant however is the speed at which low-temperature gas plasmas are finding new applications in medicine and biology, including plasma sterilization, wound healing, and cancer therapies just to name a few. In the terminology of biotechnology, the ``pipeline'' is long and exciting. This presentation reviews the current status of the field with a particular emphasis on plasma inactivation of microorganisms and biomolecules, for which comprehensive scientific evidence has been obtained. Some of the early speculations of biocidal plasma species are now being confirmed through a combination of optical emission spectroscopy, laser-induced fluorescence, mass spectrometry, fluid simulation and biological sensing with mutated bacteria. Similarly, fundamental studies are being performed to examine cell components targeted by gas plasmas, from membrane, through lipid and membrane proteins, to DNA. Scientific challenge is significant, as the usual complexity of plasma dynamics and plasma chemistry is compounded by the added complication that cells are live and constantly evolving. Nevertheless, the current understanding of plasma inactivation currently provides strong momentum for plasma decontamination technologies to be realized in healthcare. We will discuss the issue of protein and tissue contaminations of surgical instruments and how cold atmospheric plasmas may be used to degrade and reduce their surface load. In the context of plasma interaction with biomolecules, we will consider recent data of plasma degradation of adhesion proteins of melanoma cells. These adhesion proteins are important for cancer cell migration and spread. If low-temperature plasmas could be used to

  20. Impacts of friction stir processing on irradiation effects in vacuum-plasma-spray coated tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Ozawa, Kazumi, E-mail: ozawa.kazumi@jaea.go.jp [Fusion Research and Development Directorate, Japan Atomic Energy Agency, 2-166 Obuchi-Omotedate, Rokkasho, Aomori 039-3212 (Japan); Tanigawa, Hiroyasu [Fusion Research and Development Directorate, Japan Atomic Energy Agency, 2-166 Obuchi-Omotedate, Rokkasho, Aomori 039-3212 (Japan); Morisada, Yoshiaki; Fujii, Hidetoshi [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

    2015-10-15

    In order to examine the impacts of friction stir processing (FSP) on irradiation effects in vacuum-plasma-spray (VPS) coated tungsten (W), nano indentation hardness was evaluated of three kinds of W materials after self-ion-irradiation to 5.0–5.4 dpa at 500 and 800 °C. The VPS-FSP clearly got grains refined and isotropic compared to bulk-W and the as-VPS-W. Nano indentation hardness remains unchanged for the as-VPS-W and VPS-FSP × 2-W irradiated to 5.4 dpa at 500 °C and it decreased from 1 dpa at 800 °C, while typical irradiation induced hardening was observed for the bulk-W irradiated at 500 °C.

  1. Mechanical Properties of Air Plasma Sprayed Environmental Barrier Coating (EBC) Materials

    Science.gov (United States)

    Richards, Bradley; Zhu, Dongming; Ghosn, Louis; Wadley, Haydn

    2015-01-01

    Development work in Environmental Barrier Coatings (EBCs) for Ceramic Matrix Composites (CMCs) has focused considerably on the identification of materials systems and coating architectures to meet application needs. The evolution of these systems has occurred so quickly that modeling efforts and requisite data for modeling lag considerably behind development. Materials property data exists for many systems in the bulk form, but the effects of deposition on the critical properties of strength and fracture behavior are not well studied. We have plasma sprayed bulk samples of baseline EBC materials (silicon, ytterbium disilicate) and tested the mechanical properties of these materials to elicit differences in strength and toughness. We have also endeavored to assess the mixed-mode fracture resistance, Gc, of silicon in a baseline EBC applied to SiCSiC CMC via four point bend test. These results are compared to previously determined properties of the comparable bulk material.

  2. Determination of the Mechanical Properties of Plasma-Sprayed Hydroxyapatite Coatings Using the Knoop Indentation Technique

    Science.gov (United States)

    Hasan, Md. Fahad; Wang, James; Berndt, Christopher

    2015-06-01

    The microhardness and elastic modulus of plasma-sprayed hydroxyapatite coatings were evaluated using Knoop indentation on the cross section and on the top surface. The effects of indentation angle, testing direction, measurement location and applied load on the microhardness and elastic modulus were investigated. The variability and distribution of the microhardness and elastic modulus data were statistically analysed using the Weibull modulus distribution. The results indicate that the dependence of microhardness and elastic modulus on the indentation angle exhibits a parabolic shape. Dependence of the microhardness values on the indentation angle follows Pythagoras's theorem. The microhardness, Weibull modulus of microhardness and Weibull modulus of elastic modulus reach their maximum at the central position (175 µm) on the cross section of the coatings. The Weibull modulus of microhardness revealed similar values throughout the thickness, and the Weibull modulus of elastic modulus shows higher values on the top surface compared to the cross section.

  3. Failure modes of vacuum plasma spray tungsten coating created on carbon fibre composites under thermal loads

    Science.gov (United States)

    Hirai, T.; Bekris, N.; Coad, J. P.; Grisolia, C.; Linke, J.; Maier, H.; Matthews, G. F.; Philipps, V.; Wessel, E.

    2009-07-01

    Vacuum plasma spray tungsten (VPS-W) coating created on a carbon fibre reinforced composite (CFC) was tested under two thermal load schemes in the electron beam facility to examine the operation limits and failure modes. In cyclic ELM-like short transient thermal loads, the VPS-W coating was destroyed sub-layer by sub-layer at 0.33 GW/m 2 for 1 ms pulse duration. At longer single pulses, simulating steady-state thermal loads, the coating was destroyed at surface temperatures above 2700 °C by melting of the rhenium containing multilayer at the interface between VPS-W and CFC. The operation limits and failure modes of the VPS-W coating in the thermal load schemes are discussed in detail.

  4. On the 'rocket' effect during plasma arc spraying

    Energy Technology Data Exchange (ETDEWEB)

    Nemchinsky, Valerian [ESAB Welding and Cutting Products, Florence, SC 29501 (United States) and Francis Marion University, Florence, SC 29501 (United States)

    2006-06-21

    A particle's surface is not heated uniformly during plasma arc spraying: the side of the surface that faces the torch is hotter than the opposite side. If the particle temperature is high enough for substantial evaporation to occur, the imbalance of the vapour pressure gives rise to a net recoil force accelerating the particle toward the substrate. Estimations show that if particle loss of mass due to evaporation {delta}M > M {radical}(2k{sub B}T/m)/U{sub d}, the suggested effect is as important for particle dynamics as aerodynamic drag. (M is the particle mass, U{sub d} is the particle speed and {radical}(2k{sub B}T/m) is the speed of the evaporating atom, m is its mass, and T is the particle surface temperature.)

  5. CMAS Interactions with Advanced Environmental Barrier Coatings Deposited via Plasma Spray- Physical Vapor Deposition

    Science.gov (United States)

    Harder, B. J.; Wiesner, V. L.; Zhu, D.; Johnson, N. S.

    2017-01-01

    Materials for advanced turbine engines are expected to have temperature capabilities in the range of 1370-1500C. At these temperatures the ingestion of sand and dust particulate can result in the formation of corrosive glass deposits referred to as CMAS. The presence of this glass can both thermomechanically and thermochemically significantly degrade protective coatings on metallic and ceramic components. Plasma Spray- Physical Vapor Deposition (PS-PVD) was used to deposit advanced environmental barrier coating (EBC) systems for investigation on their interaction with CMAS compositions. Coatings were exposed to CMAS and furnace tested in air from 1 to 50 hours at temperatures ranging from 1200-1500C. Coating composition and crystal structure were tracked with X-ray diffraction and microstructure with electron microscopy.

  6. Repulsive Interaction of Sulfide Layers on Compressor Impeller Blades Remanufactured Through Plasma Spray Welding

    Science.gov (United States)

    Chang, Y.; Zhou, D.; Wang, Y. L.; Huang, H. H.

    2016-12-01

    This study investigated the repulsive interaction of sulfide layers on compressor impeller blades remanufactured through plasma spray welding (PSW). Sulfide layers on the blades made of FV(520)B steel were prepared through multifarious corrosion experiments, and PSW was utilized to remanufacture blade specimens. The specimens were evaluated through optical microscopy, scanning electron microscopy, energy-dispersive spectroscopy, 3D surface topography, x-ray diffraction, ImageJ software analysis, Vicker's micro-hardness test and tensile tests. Results showed a large number of sulfide inclusions in the fusion zone generated by sulfide layers embodied into the molten pool during PSW. These sulfide inclusions seriously degraded the mechanical performance of the blades remanufactured through PSW.

  7. Comparative Evaluation of Osseointegration of Dental Endodontic Implants with and without Plasma- Sprayed Hydroxy apatite Coating

    Directory of Open Access Journals (Sweden)

    Moosavi SB

    2001-05-01

    Full Text Available Bone osseointegration around dental implant can cause earlier stabilization and fixation of implant and reduce healing time. Hydroxyapatite coating can affect bone osseointegration and enhance its rates. The aim of this study was comparison of osseointegration between plasma sprayed hydroxyapatite coated and uncoated dental implants in cats. Four endodontic implants including, vitallium and two stainless steel with and without hydroxyapatite coating were prepared and placed in mandibular canines of 20 cats after completion of root canal treatment and osseous preparation. After a healing period of 4 months, investigation by scanning electron microscopy showed significant difference in ossointegration between coated and uncoated dental implants and average bone osseointegration of coated implants was more than uncoated implants.

  8. Constrained sintering of an air-plasma-sprayed thermal barrier coating

    Energy Technology Data Exchange (ETDEWEB)

    Cocks, A.C.F., E-mail: alan.cocks@eng.ox.ac.uk [Department of Engineering Science, Parks Rd., Oxford OX1 3PJ (United Kingdom); Fleck, N.A. [Cambridge University Engineering Department, Trumpington St., Cambridge CB2 1PZ (United Kingdom)

    2010-07-15

    A micromechanical model is presented for the constrained sintering of an air-plasma-sprayed, thermal barrier coating upon a thick superalloy substrate. The coating comprises random splats with intervening penny-shaped cracks. The crack faces make contact at asperities, which progressively sinter in-service by interfacial diffusion, accommodated by bulk creep. Diffusion is driven by the reduction in interfacial energy at the developing contacts and by the local asperity contact stress. At elevated operating temperature, both sintering and creep strains accumulate within the plane of the coating. The sensitivities of sintering rate and microstructure evolution rate to the kinetic parameters and thermodynamic driving forces are explored. It is demonstrated that the sintering response is governed by three independent timescales, as dictated by the material and geometric properties of the coating. Finally, the role of substrate constraint is assessed by comparing the rate of constrained sintering with that for free sintering.

  9. Low Pressure Plasma Sprayed Overlay Coatings for GRCop-84 Combustion Chamber Liners for Reusable Launch Vehicles

    Science.gov (United States)

    Raj, S. V.; Barrett, C.; Ghosn, L. J.; Lerch, B.; Robinson,; Thorn, G.

    2005-01-01

    An advanced Cu-8(at.%)Cr-4%Nb alloy developed at NASA's Glenn Research Center, and designated as GRCop-84, is currently being considered for use as combustor chamber liners and nozzle ramps in NASA s future generations of reusable launch vehicles (RLVs). However, past experience has shown that unprotected copper alloys undergo an environmental attack called "blanching" in rocket engines using liquid hydrogen as fuel and liquid oxygen as the oxidizer. Potential for sulfidation attack of the liners in hydrocarbon-fueled engines is also of concern. Protective overlay coatings alloys are being developed for GRCop-84. The development of this coatings technology has involved a combination of modeling, coatings development and characterization, and process optimization. Coatings have been low pressure plasma sprayed on GRCop-84 substrates of various geometries and shapes. Microstructural, mechanical property data and thermophysical results on the coated substrates are presented and discussed.

  10. Manufacture of NiAl-based rods for plasma centrifugal spraying using mechanochemical synthesis

    Science.gov (United States)

    Logacheva, A. I.; Gusakov, M. S.; Sentyurina, Zh. A.; Logachev, I. A.; Kandyba, A. A.

    2017-05-01

    An alternative technology is proposed for the production of NiAl-Co-Cr-Hf-Al2O3 alloy rods. It includes the fabrication of a powder by mechanochemical synthesis (MCS) followed by hot isostatic pressing in forming tool. The processes of MCS of the intermetallic alloy in a planetary mill and an attritor are studied. The products of synthesis in various mixers are compared. The microstructure and the properties of compacted samples are studied: their ultimate compressive strength is 1390-1480 MPa at a plasticity of 8.5-8.8%. Spherical granules with a target size of 20-200 μm are fabricated by plasma centrifugal spraying of the rod workpiece formed by the proposed technology.

  11. Application of atmospheric pressure plasma in polymer and composite adhesion

    Science.gov (United States)

    Yu, Hang

    An atmospheric pressure helium and oxygen plasma was used to investigate surface activation and bonding in polymer composites. This device was operated by passing 1.0-3.0 vol% of oxygen in helium through a pair of parallel plate metal electrodes powered by 13.56 or 27.12 MHz radio frequency power. The gases were partially ionized between the capacitors where plasma was generated. The reactive species in the plasma were carried downstream by the gas flow to treat the substrate surface. The temperature of the plasm gas reaching the surface of the substrate did not exceed 150 °C, which makes it suitable for polymer processing. The reactive species in the plasma downstream includes ~ 1016-1017 cm-3 atomic oxygen, ~ 1015 cm-3 ozone molecule, and ~ 10 16 cm-3 metastable oxygen molecule (O2 1Deltag). The substrates were treated at 2-5 mm distance from the exit of the plasma. Surface properties of the substrates were characterized using water contact angle (WCA), atomic force microscopy (AFM), infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS). Subsequently, the plasma treated samples were bonded adhesively or fabricated into composites. The increase in mechanical strength was correlated to changes in the material composition and structure after plasma treatment. The work presented hereafter establishes atmospheric pressure plasma as an effective method to activate and to clean the surfaces of polymers and composites for bonding. This application can be further expanded to the activation of carbon fibers for better fiber-resin interactions during the fabrication of composites. Treating electronic grade FR-4 and polyimide with the He/O2 plasma for a few seconds changed the substrate surface from hydrophobic to hydrophilic, which allowed complete wetting of the surface by epoxy in underfill applications. Characterization of the surface by X-ray photoelectron spectroscopy shows formation of oxygenated functional groups, including hydroxyl, carbonyl, and

  12. Study of the characteristics of plasma spray sealing aluminum silicon-polyester coatings

    Directory of Open Access Journals (Sweden)

    Mihailo R. Mrdak

    2012-07-01

    Full Text Available This study shows the homologation of the plasma spray parameters of soft abrasive AlSi - Polyester seals so that they can be applied on the TV2 - 117A compressor engines. The research has aimed at substituting existing sealants with a new class of materials in order to increase the sealing effect under the highest levels of pressure and to provide the air flow temperature of 100-125°C through the compressor. The Metco 601NS material and plasma spray technology were applied on the air labyrinth ring as a part of the TV2-117A turbojet engine compressor in order to obtain soft sealing. The deposit parameters were carefully selected in order to obtain coatings with the best characteristics depending on their application.The flow of helium was taken as a basic parameter in the parameter selection procedure. The coating with the best mechanical and structural properties was deposited on the air labyrinth ring to examine the effect of the coating application in an assembly. The microstructures of deposited layers were estimated with a light microscope and a (SEM Scanning Electron Microscope. The microstructural analysis of deposited layers was performed according to the Pratt - Whitney standard. The assessment of the mechanical properties of the coatings was done by examining the macrohardness of the sealing layers with the HR15Y method. The coating bond strength was tested by tensile testing. The effect of the air labyrinth ring sealing was tested inside the TV2-117A engine compressor on the test station for a period of 42 hour.

  13. Exploration to generate atmospheric pressure glow discharge plasma in air

    Science.gov (United States)

    Wenzheng, LIU; Chuanlong, MA; Shuai, ZHAO; Xiaozhong, CHEN; Tahan, WANG; Luxiang, ZHAO; Zhiyi, LI; Jiangqi, NIU; Liying, ZHU; Maolin, CHAI

    2018-03-01

    Atmospheric pressure glow discharge (APGD) plasma in air has high application value. In this paper, the methods of generating APGD plasma in air are discussed, and the characteristics of dielectric barrier discharge (DBD) in non-uniform electric field are studied. It makes sure that APGD in air is formed by DBD in alternating current electric field with using the absorbing electron capacity of electret materials to provide initial electrons and to end the discharge progress. Through designing electric field to form two-dimensional space varying electric field and three-dimensional space varying electric field, the development of electron avalanches in air-gap is suppressed effectively and a large space of APGD plasma in air is generated. Further, through combining electrode structures, a large area of APGD plasma in air is generated. On the other hand, by using the method of increasing the density of initial electrons, millimeter-gap glow discharge in atmospheric pressure air is formed, and a maximum gap distance between electrodes is 8 mm. By using the APGD plasma surface treatment device composed of contact electrodes, the surface modification of high polymer materials such as aramid fiber and polyester are studied and good effect of modifications is obtained. The present paper provides references for the researchers of industrial applications of plasma.

  14. Diagnostics of atmospheric pressure capillary DBD oxygen plasma jet

    CERN Document Server

    Roy, N C; Pramanik, B K

    2015-01-01

    Atmospheric pressure capillary dielectric barrier oxygen discharge plasma jet is developed to generate non-thermal plasma using unipolar positive pulse power supply. Both optical and electrical techniques are used to investigate the characteristics of the produced plasma as function of applied voltage and gas flow rate. Analytical results obtained from the optical emission spectroscopic data reveal the gas temperature, rotational temperature, excitation temperature and electron density. Gas temperature and rotational temperature are found to decrease with increasing oxygen flow rate but increase linearly with applied voltage. It is exposed that the electron density is boosting up with enhanced applied voltage and oxygen flow rate, while the electron excitation temperature is reducing with rising oxygen flow rate. Electrical characterization demonstrates that the discharge frequency is falling with flow rate but increasing with voltage. The produced plasma is applied preliminarily to study the inactivation yie...

  15. Cold Atmospheric Plasma Technology for Decontamination of Space Equipment

    Science.gov (United States)

    Thomas, Hubertus; Rettberg, Petra; Shimizu, Tetsuji; Thoma, Markus; Morfill, Gregor; Zimmermann, Julia; Müller, Meike; Semenov, Igor

    2016-07-01

    Cold atmospheric plasma (CAP) technology is very fast and effective in inactivation of all kinds of pathogens. It is used in hygiene and especially in medicine, since the plasma treatment can be applied to sensitive surfaces, like skin, too. In a first study to use CAP for the decontamination of space equipment we could show its potential as a quite promising alternative to the standard "dry heat" and H2O2 methods [Shimizu et al. Planetary and Space Science, 90, 60-71. (2014)]. In a follow-on study we continue the investigations to reach high application level of the technology. First, we redesign the actual setup to a plasma-gas circulation system, increasing the effectivity of inactivation and the sustainability. Additionally, we want to learn more about the plasma chemistry processes involved in the inactivation. Therefore, we perform detailed plasma and gas measurements and compare them to numerical simulations. The latter will finally be used to scale the decontamination system to sizes useful also for larger space equipment. Typical materials relevant for space equipment will be tested and investigated on surface material changes due to the plasma treatment. Additionally, it is planned to use electronic boards and compare their functionality before and after the CAP expose. We will give an overview on the status of the plasma decontamination project funded by the Bavarian Ministry of Economics.

  16. Compact atmospheric pressure plasma self-resonant drive circuits

    Science.gov (United States)

    Law, V. J.; Anghel, S. D.

    2012-02-01

    This paper reports on compact solid-state self-resonant drive circuits that are specifically designed to drive an atmospheric pressure plasma jet and a parallel-plate dielectric barrier discharge of small volume (0.5 cm3). The atmospheric pressure plasma (APP) device can be operated with helium, argon or a mixture of both. Equivalent electrical models of the self-resonant drive circuits and discharge are developed and used to estimate the plasma impedance, plasma power density, current density or electron number density of three APP devices. These parameters and the kinetic gas temperature are dependent on the self-resonant frequency of the APP device. For a fixed switching frequency and APP device geometry, the plasma parameters are controlled by adjusting the dc voltage at the primary coil and the gas flow rate. The resonant frequency is controlled by the selection of the switching power transistor and means of step-up voltage transformation (ferrite core, flyback transformer, or Tesla coil). The flyback transformer operates in the tens of kHz, the ferrite core in the hundreds of kHz and Tesla coil in the MHz range. Embedded within this work is the principle of frequency pulling which is exemplified in the flyback transformer circuit that utilizes a pickup coil for feedback control of the switching frequency.

  17. Microstructural characterization of radio frequency and direct current plasma-sprayed Al2O3 coatings

    Science.gov (United States)

    Chen, H. C.; Pfender, E.; Dzur, B.; Nutsch, G.

    2000-06-01

    Microstructures of radio frequency (RF) and direct current (DC) plasma-sprayed Al2O3 coatings deposited onto steel substrates were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), electron microprobe analysis (EMPA), polarizing optical microscopy (OM), and transmission electron microscopy (TEM). Because RF and DC plasmas produce different particle heating and acceleration, the morphology, phase structure, and fracture modes of the coatings vary substantially. In the case of RF coatings, a clear lamellar microstructure with relatively thick lamellae was observed, which is due to the large particles and the low particle velocities, with α-Al2O3 as the predominant phase and with delamination type of fracture detected on the fracture surface. In contrast, the DC coatings consisted of predominantly metastable γ-Al2O3 as well as amorphous phases, with a mixed fracture mode of the coating observed. In spite of limited interfacial interdiffusion detected by EMPA, TEM showed an interfacial layer existing at the interface between the coating and the substrate for both cases. For RF coatings, the interfacial layer on the order of 1 µm was composed of three sublayers, each of which was different in composition and morphology. However, the interfacial layer for the DC coating consisted primarily of an amorphous phase, containing both coating and substrate materials with or without platelike microcrystals; although in some regions a thick amorphous Al2O3 layer was in direct contact with the substrate.

  18. Evaluation and Characterization of Plasma Sprayed Cu Slag-Al Composite Coatings on Metal Substrates

    Directory of Open Access Journals (Sweden)

    S. Mantry

    2013-01-01

    Full Text Available Copper slag is a waste product obtained during matte smelting and refining of copper. The present work explores the coating potential of copper slag by plasma spraying. This work shows that copper slag is eminently coatable. An attempt has been made in the present investigation to use the composites coatings of copper slag and Al powder in suitable combination on aluminium and mild steel substrates in order to improve the surface properties of these ductile metal-alloy substrates. When premixed with Al powder, the coating exhibits higher interfacial adhesion as compared to pure copper slag coatings. Maximum adhesion strengths of about 23 MPa and 21 MPa are recorded for the coatings of copper slag with 15 wt% of Al on aluminium and mild steel substrates, respectively. The input power to the plasma torch is found to affect the coating deposition efficiency and morphology of the coatings. It also suggests value addition of an industrial waste.

  19. Modeling fragmentation of plasma-sprayed particles impacting on a solid surface at room temperature

    Science.gov (United States)

    McDonald, André; Xue, Michelle; Chandra, Sanjeev; Mostaghimi, Javad; Moreau, Christian

    2007-05-01

    Molybdenum particles were melted and accelerated by a plasma jet to impact on glass surfaces held at room temperature. A fast charge-coupled device (CCD) camera was triggered to capture images of the particles during spreading. Splats on the glass held at ambient temperature fragmented, leaving only a solidified central core. A 3D model of droplet impact and solidification was used to simulate the impact and spreading of these plasma-sprayed particles. The thermal contact resistance, which was estimated from an existing heat conduction model, was used as an input parameter in the 3D model. It was found that the thermal contact resistance between the splat central core and the glass was two orders of magnitude lower than that between the rest of the splat fluid and the surface. This suggests that the physical contact between the fluid in the splat central core and the glass surface can be improved by the large pressure generated during impact. To cite this article: A. McDonald et al., C. R. Mecanique 335 (2007).

  20. Advanced Vacuum Plasma Spray (VPS) for a Robust, Longlife and Safe Space Shuttle Main Engine (SSME)

    Science.gov (United States)

    Holmes, Richard R.; Elam, Sandra K.; McKechnie, Timothy N.; Power, Christopher A.

    2010-01-01

    In 1984, the Vacuum Plasma Spray Lab was built at NASA/Marshall Space Flight Center for applying durable, protective coatings to turbine blades for the space shuttle main engine (SSME) high pressure fuel turbopump. Existing turbine blades were cracking and breaking off after five hot fire tests while VPS coated turbine blades showed no wear or cracking after 40 hot fire tests. Following that, a major manufacturing problem of copper coatings peeling off the SSME Titanium Main Fuel Valve Housing was corrected with a tenacious VPS copper coating. A patented VPS process utilizing Functional Gradient Material (FGM) application was developed to build ceramic lined metallic cartridges for space furnace experiments, safely containing gallium arsenide at 1260 degrees centigrade. The VPS/FGM process was then translated to build robust, long life, liquid rocket combustion chambers for the space shuttle main engine. A 5K (5,000 Lb. thrust) thruster with the VPS/FGM protective coating experienced 220 hot firing tests in pristine condition with no wear compared to the SSME which showed blanching (surface pulverization) and cooling channel cracks in less than 30 of the same hot firing tests. After 35 of the hot firing tests, the injector face plates disintegrated. The VPS/FGM process was then applied to spraying protective thermal barrier coatings on the face plates which showed 50% cooler operating temperature, with no wear after 50 hot fire tests. Cooling channels were closed out in two weeks, compared to one year for the SSME. Working up the TRL (Technology Readiness Level) to establish the VPS/FGM process as viable technology, a 40K thruster was built and is currently being tested. Proposed is to build a J-2X size liquid rocket engine as the final step in establishing the VPS/FGM process TRL for space flight.

  1. Effects of isothermal treatment on microstructure and scratch test behavior of plasma sprayed zirconia coatings

    Directory of Open Access Journals (Sweden)

    Veloso Guilherme

    2004-01-01

    Full Text Available The increase of the petroleum cost in the last decades revitalized the interest for lighter and more economic vehicles. Simultaneously, the demand for safe and unpolluted transports grows. The application of thermal barriers coatings (TBC on combustion chamber and on flat surface of pistons reduces the thermal losses of the engines, resulting in higher temperatures in the combustion chamber. This fact contributes to the improvement of the thermal efficiency (performance and for the reduction of incomplete combustion. Supported on these initial ideas, thermal barriers coatings constituted by CaO partially stabilized zirconia were produced and their microstructure examined. This coating still presents some drawbacks associated with thermal stresses and permeability to oxidizing gases, which will, eventually, lead to failure of the TBC by spallation. The failure may, in general, be associated to one of three factors: oxide growth at the ceramic-metal interface, formed during thermal cycling; stress build-up due to thermal cycling; and metal-oxide interface segregation, mainly of S. However, it is also relevant to understand the behavior of TBC's under isothermal oxidation. Therefore, this paper investigates the effect of oxidation on the adherence of thermal sprayed coatings. The adherence was measured by linear scratching tests, widely used for thin coatings. Plasma sprayed calcia partially stabilized zirconia was used as TBC and Ni-5%Al as bond coat, with Al substrates. Coated samples were submitted to heat treatments at 500 °C, for 50 h. The microstructures were examined by optical light microscopy, X-ray diffraction, profilometry and SEM.

  2. Capacity-coupled multidischarge for atmospheric plasma production

    Science.gov (United States)

    Mase, Hiroshi; Fujiwara, Tamiya; Sato, Noriyoshi

    2003-12-01

    We propose a method of plasma production by capacity-coupled multidischarge (CCMD) at atmospheric pressure. The discharge gaps in the CCMD consist of a common electrode and a number of compact electrodes (CCE) which are directly coupled with small capacitors for quenching the discharge. A simple CCE structure is provided by a cylindrical capacitor, the inner conductor of which is used as a gap electrode. A short pulse discharge is observed to appear homogeneously at each CCE. A charge transfer for the single-pulsed discharge is 10-100 times as large as that of the conventional dielectric barrier discharge. A high efficiency of ozone production has been confirmed in the CCMD using O2 gas. A device configuration of the CCMD is quite flexible with respect to its geometrical shape and size. The CCMD could be used to produce plasmas for various kinds of industrial applications at atmospheric pressure.

  3. Controlling Microstructure of Yttria-Stabilized Zirconia Prepared from Suspensions and Solutions by Plasma Spraying with High Feed Rates

    Science.gov (United States)

    Musalek, Radek; Medricky, Jan; Tesar, Tomas; Kotlan, Jiri; Pala, Zdenek; Lukac, Frantisek; Illkova, Ksenia; Hlina, Michal; Chraska, Tomas; Sokolowski, Pawel; Curry, Nicholas

    2017-12-01

    Introduction of suspension and solution plasma spraying led to a breakthrough in the deposition of yttria-stabilized zirconia (YSZ) coatings and enabled preparation of new types of layers. However, their deposition with high feed rates needed, for example, for the deposition of thermal barrier coatings (TBCs) on large-scale components, is still challenging. In this study, possibility of high-throughput plasma spraying of YSZ coatings is demonstrated for the latest generation of high-enthalpy hybrid water-stabilized plasma (WSP-H) torch technology. The results show that microstructure of the coatings prepared by WSP-H may be tailored for specific applications by the choice of deposition conditions, in particular formulation of the liquid feedstock. Porous and columnar coatings with low thermal conductivity (0.5-0.6 W/mK) were prepared from commercial ethanol-based suspension. Dense vertically cracked coatings with higher thermal conductivity but also higher internal cohesion were deposited from suspension containing ethanol/water mixture and coarser YSZ particles. Spraying of solution formulated from diluted zirconium acetate and yttrium nitrate hexahydrate led also to the successful deposition of YSZ coating combining regions of porous and denser microstructure and providing both low thermal conductivity and improved cohesion of the coating. Enthalpy content, liquid-plasma interaction and coating buildup mechanisms are also discussed.

  4. THE EFFECTS OF PLASMA SPRAY PARAMETERS ON THE MICROSTRUCTURE AND PHASE COMPOSITION OF THERMAL BARRIER COATINGS MADE BY SPPS PROCESS

    Directory of Open Access Journals (Sweden)

    Z. Valefi

    2017-06-01

    Full Text Available In this paper the effect of plasma spray parameters, atomizing gas and substrate preheat temperature on microstructure and phase composition of YSZ coatings produced by SPPS process have been investigated. The experimental results showed that increasing the power of plasma, using hydrogen as the precursor atomizing gas and increasing substrate preheat temperature decrease the amount of non-pyrolyzed precursor in the coatings. At low plasma power most of the deposited precursor is in non-pyrolyzed state, and consequently the applied coatings are defective. The increase in substrate temperature beyond 800oC either by preheating or heat transfer from plasma torch to the substrate, prevent the coating formation. In SPPS coating formation, up to a special spray distance the optical microscopy image of the coatings showed a snowy like appearance. XRD analysis showed that in this situation the amount of un-pyrolyzed precursor is low. Beyond this spray distance, spherical particles, are obtained and XRD analysis showed that most of the precursor is in un-pyrolyzed state.

  5. Very Low Pressure Plasma Spray—A Review of an Emerging Technology in the Thermal Spray Community

    Directory of Open Access Journals (Sweden)

    Mark F. Smith

    2011-12-01

    Full Text Available A fundamentally new family of thermal spray processes has emerged. These new processes, collectively known as very low pressure plasma spray or VLPPS, differ from traditional thermal spray processes in that coatings are deposited at unusually low chamber pressures, typically less than ~800 Pa (6 Torr. Depending upon the specific process, deposition may be in the form of very fine molten droplets, vapor phase deposition, or a mixture of vapor and droplet deposition. Resulting coatings are similar in quality to coatings produced by alternative coating technologies, such as physical vapor deposition (PVD or chemical vapor deposition (CVD, but deposition rates can be roughly an order of magnitude higher with VLPPS. With these new process technologies modified low pressure plasma spray (LPPS systems can now be used to produce dense, high quality coatings in the 1 to 100 micron thickness range with lamellar or columnar microstructures. A history of pioneering work in VLPPS technology is presented, deposition mechanisms are discussed, potential new applications are reviewed, and challenges for the future are outlined.

  6. An Assessment of the Residual Stresses in Low Pressure Plasma Sprayed Coatings on an Advanced Copper Alloy

    Science.gov (United States)

    Raj, S. V.; Ghosn, L. J.; Agarwal, A.; Lachtrupp, T. P.

    2002-01-01

    Modeling studies were conducted on low pressure plasma sprayed (LPPS) NiAl top coat applied to an advanced Cu-8(at.%)Cr-4%Nb alloy (GRCop-84) substrate using Ni as a bond coat. A thermal analysis suggested that the NiAl and Ni top and bond coats, respectively, would provide adequate thermal protection to the GRCop-84 substrate in a rocket engine operating under high heat flux conditions. Residual stress measurements were conducted at different depths from the free surface on coated and uncoated GRCop-84 specimens by x-ray diffraction. These data are compared with theoretically estimated values assessed by a finite element analysis simulating the development of these stresses as the coated substrate cools down from the plasma spraying temperature to room temperature.

  7. Preliminary study of cyclic thermal shock resistance of plasma-sprayed zirconium oxide turbine outer air seal shrouds

    Science.gov (United States)

    Bill, R. C.; Wisander, D. W.

    1977-01-01

    Several experimental concepts representing potential high pressure turbine seal material systems were subjected to cyclic thermal shock exposures similar to those that might be encountered under severe engine start-up and shut-down sequences. All of the experimental concepts consisted of plasma-sprayed yttria stabilized ZrO2 on the high temperature side of the blade tip seal shroud. Between the ZrO2 and a cooled, dense metal backing, various intermediate layer concepts intended to mitigate thermal stresses were incorporated. Performance was judged on the basis of the number of thermal shock cycles required to cause loss of seal material through spallation. The most effective approach was to include a low modulus, sintered metal pad between the ZrO2 and the metallic backing. It was also found that reducing the density of the ZrO2 layer significantly improved the performance of specimens with plasma-sprayed metal/ceramic composite intermediate layers.

  8. A cost- and time-saving strategy of spraying TiO2 self-cleaning coatings in tubular substrates by air cold plasma

    Science.gov (United States)

    Zhang, Lujie; Yu, Shuang; Wang, Kaile; Zhang, Jue; Fang, Jing

    2017-11-01

    In this study, using an atmospheric pressure air plasma jet generated by a dielectric barrier structure with hollow electrodes (HEDBS), we developed an ultrafast process for spraying TiO2 self-cleaning films inside tubular substrates. Importantly, SEM images showed that the TiO2 particles were dispersed evenly in the tubular substrates. Furthermore, Raman and XRD pattern indicated the anatase structure of the HEDBS-spayed TiO2 coating after heating at 270 °C. Further results of the self cleaning test suggested that the proposed cost- and time-saving HEDBS approach with air working gas could provide a feasible way for synthesizing thin TiO2 nanofilms.

  9. Plasma Processing with a One Atmosphere Uniform Glow Discharge Plasma (OAUGDP)

    Science.gov (United States)

    Reece Roth, J.

    2000-10-01

    The vast majority of all industrial plasma processing is conducted with glow discharges at pressures below 10 torr. This has limited applications to high value workpieces as a result of the large capital cost of vacuum systems and the production constraints of batch processing. It has long been recognized that glow discharges would play a much larger industrial role if they could be operated at one atmosphere. The One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) has been developed at the University of Tennessee Plasma Sciences Laboratory. The OAUGDP is non-thermal RF plasma with the time-resolved characteristics of a classical low pressure DC normal glow discharge. An interdisciplinary team was formed to conduct exploratory investigations of the physics and applications of the OAUGDP. This team includes collaborators from the UTK Textiles and Nonwovens Development Center (TANDEC) and the Departments of Electrical and Computer Engineering, Microbiology, Food Science and Technology, and Mechanical and Aerospace Engineering and Engineering Science. Exploratory tests were conducted on a variety of potential plasma processing and other applications. These include the use of OAUGDP to sterilize medical and dental equipment and air filters; diesel soot removal; plasma aerodynamic effects; electrohydrodynamic (EDH) flow control of the neutral working gas; increasing the surface energy of materials; increasing the wettability and wickability of fabrics; and plasma deposition and directional etching. A general overview of these topics will be presented.

  10. Atmospheric pressure plasma accelerates tail regeneration in tadpoles Xenopus laevis

    Science.gov (United States)

    Rivie, A.; Martus, K.; Menon, J.

    2017-08-01

    Atmospheric pressure plasma is a partially ionized gas composed of neutral and charged particles, including electrons and ions, as well as reactive oxygen species (ROS). Recently, it is utilized as possible therapy in oncology, sterilization, skin diseases, wound healing and tissue regeneration. In this study we focused on effect of plasma exposure on tail regeneration of tadpoles, Xenopus leavis with special emphasis on role of ROS, antioxidant defenses and morphological features of the regenerate. When amputated region of the tail was exposed to the helium plasma it resulted in a faster rate of growth, elevated ROS and increase in antioxidant enzymes in the regenerate compared to that of untreated control. An increase in nitric oxide (free radical) as well as activity of nitric oxide synthase(s) were observed once the cells of the regeneration blastema - a mass of proliferating cells are ready for differentiation. Microscopically the cells of the regenerate of plasma treated tadpoles show altered morphology and characteristics of cellular hypoxia and oxidative stress. We summarize that plasma exposure accelerates the dynamics of wound healing and tail regeneration through its effects on cell proliferation and differentiation as well as angiogenesis mediated through ROS signaling.

  11. Dynamics of apokamp-type atmospheric pressure plasma jets

    Science.gov (United States)

    Sosnin, Eduard A.; Panarin, Victor A.; Skakun, Victor S.; Baksht, Evgeny Kh.; Tarasenko, Victor F.

    2017-02-01

    The paper describes a new discharge source of atmospheric pressure plasma jets (APPJs) in air with no gas supply through the discharge region. In this discharge mode, plasma jets develop from the bending point of a bright current channel between two electrodes and are therefore termed an apokamp (from Greek `off' and `bend'). The apokamp can represent single plasma jets of length up 6 cm or several jets, and the temperature of such jets can range from more than 1000 °C at their base to 100-250 °C at their tip. Apokamps are formed at maximum applied voltage of positive polarity, provided that the second electrode is capacitively decoupled with ground. According to high-speed photography with time resolution from several nanoseconds to several tens of nanoseconds, the apokamp consists of a set of plasma bullets moving with a velocity of 100-220 km/s, which excludes the convective mechanism of plasma decay. Estimates on a 100-ns scale show that the near-electrode zones and the zones from which apokamps develop are close in temperature.

  12. Plasma spray joining of aluminum matrix composites using osprey composite powder. Plasma yoshaho ni yoru Al ki fukugo zairyo no setsugo

    Energy Technology Data Exchange (ETDEWEB)

    Itsukaichi, T.; Umemoto, M.; Okane, I. (Toyohashi Univ. of Technology, Aichi (Japan)); Eagar, T.W. (Massachusetts Inst. of Technology, Massachusetts (U.S.A.))

    1992-05-05

    Plasma spraying method has comparatively high deposition rate with no need for high temperature heating of the parent material, and has vary little restrictions as to the applied materials, shape and size. Its possibility for application to the bonding of metallic matrix composites (MMC) is investigated. 6061Al alloy and 6061Al based particle reinforced composite are bonded by the plasma spraying method. No Al{sub 4}C{sub 3} phase is produced even when Osprey powder (SIC) including SiC phase is sprayed. Pyrolysis of SiC, however, is observed, and a large quantity of Si is identified in the dissolved matrix of the deposited material. Heat treatment of the sprayed joint improves the bonding strength markedly. Most of the fractures in the heat treated joint are fractures inside the deposited layer, proving that bonding characteristic between the raw material and deposited material can be improved by heat treatment. Hot isostatic pressing of MMC parent material has only little effect on the strength of the joint. 11 refs., 11 figs., 3 tabs.

  13. Elastic and plastic behavior of plasma-sprayed hydroxyapatite coatings on a Ti-6Al-4V substrate.

    Science.gov (United States)

    Zhang, C; Leng, Y; Chen, J

    2001-06-01

    A novel approach that combines the indentation tests with nonlinear finite element modeling (FEM) is proposed to estimate the elastic/plastic constitutive relation of plasma-sprayed hydroxyapatite (HA) coatings on a Ti-6Al-4V substrate. The Ramberg-Osgood constitutive equation can well describe the deformation behavior of plasma-sprayed HA coating on Ti-6Al-4V. A reasonable estimation for the elastic modulus of the HA coatings is given, based on the fact that the coating consists of a crystalline phase, an amorphous phase and pores. The Ramberg-Osgood equations of the coatings indicate that the post-treatment increases both resistance to elastic and plastic deformation, but no effect on strain hardening behavior. The post-treatment, however, could reduce the resistance to coating/substrate separation. The influence of titanium substrate becomes more significant with decreasing coating thickness and increasing indentation load because the plasma-sprayed HA coatings exhibit much less resistance to indentation deformation than does Ti-6Al-4V.

  14. A comparative physico-chemical study of chlorapatite and hydroxyapatite: from powders to plasma sprayed thin coatings.

    Science.gov (United States)

    Demnati, I; Grossin, D; Combes, C; Parco, M; Braceras, I; Rey, C

    2012-10-01

    Due to their bioactivity and osteoconductivity, hydroxyapatite (HA) plasma sprayed coatings have been widely developed for orthopedic uses. However, the thermodynamic instability of HA leads frequently to a mixture of phases which limit the functional durability of the coating. This study investigates the plasma spraying of chlorapatite (ClA) powder, known to melt without decomposition, onto pure titanium substrates using a low energy plasma spray system (LEPS). Pure ClA powder was prepared by a solid gas reaction at 950 °C and thermogravimetric analysis showed the good thermal stability of ClA powder in the range 30-1400 °C compared to that of the HA powder. Characterization of ClA coating showed that ClA had a very high crystalline ratio and no other crystalline phase was detected in the coating. HA and ClA coatings composition, microstructure and in vitro bioactivity potential were studied, compared and discussed. In vitro SBF test on HA and ClA coatings revealed the formation of a poorly crystalline apatite on the coating surface suggesting that we could expect a good osteoconductivity especially for the ClA coating prepared by the LEPS system.

  15. Plasma Sprayed Bondable Stainless Surface (BOSS) Coatings for Corrosion Protection and Adhesion Treatments

    Science.gov (United States)

    Davis, G. D.; Groff, G. B.; Rooney, M.; Cooke, A. V.; Boothe, R.

    1995-01-01

    Plasma-sprayed Bondable Stainless Surface (BOSS) coatings are being developed under the Solid Propulsion Integrity Program's (SPIP) Bondlines Package. These coatings are designed as a steel case preparation treatment prior to insulation lay-up. Other uses include the exterior of steel cases and bonding surfaces of nozzle components. They provide excellent bondability - rubber insulation and epoxy bonds fail cohesively within the polymer - for both fresh surfaces and surfaces having undergone natural and accelerated environmental aging. They have passed the MSFC requirements for protection of inland and sea coast environment. Because BOSS coatings are inherently corrosion resistant, they do not require preservation by greases or oils. The reduction/elimination of greases and oils, known bondline degraders, can increase SRM reliability, decrease costs by reducing the number of process steps, and decrease environmental pollution by reducing the amount of methyl chloroform used for degreasing and thus reduce release of the ozone-depleting chemical in accordance with the Clean Air Act and the Montreal Protocol. The coatings can potential extend the life of RSRM case segments and nozzle components by eliminating erosion due to multiple grit blasting during each use cycle and corrosion damage during marine recovery. Concurrent work for the Air Force show that other BOSS coatings give excellent bondline strength and durability for high-performance structures of aluminum and titanium.

  16. Bilayer Suspension Plasma-Sprayed Thermal Barrier Coatings with Enhanced Thermal Cyclic Lifetime: Experiments and Modeling

    Science.gov (United States)

    Gupta, Mohit; Kumara, Chamara; Nylén, Per

    2017-08-01

    Suspension plasma spraying (SPS) has been shown as a promising process to produce porous columnar strain tolerant coatings for thermal barrier coatings (TBCs) in gas turbine engines. However, the highly porous structure is vulnerable to crack propagation, especially near the topcoat-bondcoat interface where high stresses are generated due to thermal cycling. A topcoat layer with high toughness near the topcoat-bondcoat interface could be beneficial to enhance thermal cyclic lifetime of SPS TBCs. In this work, a bilayer coating system consisting of first a dense layer near the topcoat-bondcoat interface followed by a porous columnar layer was fabricated by SPS using Yttria-stabilised zirconia suspension. The objective of this work was to investigate if the bilayer topcoat architecture could enhance the thermal cyclic lifetime of SPS TBCs through experiments and to understand the effect of the column gaps/vertical cracks and the dense layer on the generated stresses in the TBC during thermal cyclic loading through finite element modeling. The experimental results show that the bilayer TBC had significantly higher lifetime than the single-layer TBC. The modeling results show that the dense layer and vertical cracks are beneficial as they reduce the thermally induced stresses which thus increase the lifetime.

  17. Sterilization of Surfaces with a Handheld Atmospheric Pressure Plasma

    Science.gov (United States)

    Hicks, Robert; Habib, Sara; Chan, Wai; Gonzalez, Eleazar; Tijerina, A.; Sloan, Mark

    2009-10-01

    Low temperature, atmospheric pressure plasmas have shown great promise for decontaminating the surfaces of materials and equipment. In this study, an atmospheric pressure, oxygen and argon plasma was investigated for the destruction of viruses, bacteria, and spores. The plasma was operated at an argon flow rate of 30 L/min, an oxygen flow rate of 20 mL/min, a power density of 101.0 W/cm^3 (beam area = 5.1 cm^2), and at a distance from the surface of 7.1 mm. An average 6log10 reduction of viable spores was obtained after only 45 seconds of exposure to the reactive gas. By contrast, it takes more than 35 minutes at 121^oC to sterilize anthrax in an autoclave. The plasma properties were investigated by numerical modeling and chemical titration with nitric oxide. The numerical model included a detailed reaction mechanism for the discharge as well as for the afterglow. It was predicted that at a delivered power density of 29.3 W/cm^3, 30 L/min argon, and 0.01 volume% O2, the plasma generated 1.9 x 10^14 cm-3 O atoms, 1.6 x 10^12 cm-3 ozone, 9.3 x 10^13 cm-3 O2(^1δg), and 2.9 x 10^12 cm-3 O2(^1σ^+g) at 1 cm downstream of the source. The O atom density measured by chemical titration with NO was 6.0 x 10^14 cm-3 at the same conditions. It is believe that the oxygen atoms and the O2(^1δg) metastables were responsible for killing the anthrax and other microorganisms.

  18. Development of atmospheric pressure plasma needle jet for sterilization applications

    Science.gov (United States)

    Elfa, Rizan Rizon; Ahmad, Mohd Khairul; Soon, Chin Fhong; Sahdan, Mohd Zainizan; Lias, Jais; Wibowo, Kusnanto Mukti; Bakar, Ahmad Shuhaimi Abu; Arshad, Mohd Khairuddin Md; Hashim, Uda; Nayan, Nafarizal

    2017-09-01

    Inactivation of bacteria or sterilization has been a major issue in the medical field, especially regarding of human safety, whereby, in a huge scenario fatality can be caused by hazardous bacteria. Often, E-coli as gram-negative bacteria are selected as a key indicator of proper sterilization process as E-coli is tough and dormant bacteria. The technology in sterilization has moved on from chemical, wet and irradiation sterilization to a high promising device such as atmospheric pressure plasma needle jet (APPNJ). It has been reported that atmospheric pressure plasma has provided bundle of advantages over earlier sterilization process. The APPNJ is developed in our lab using high frequency and high voltage neon transformer power supply connected to copper needle and copper sheet electrodes. The gas discharge is Ar gas flowing at 40 L/min through a quartz glass tube. The E-coli bacteria are self-cultured from waste water and then treated with APPNJ. The treatment processes are run into two difference gaps between the plasma orifice and sample with various treatment times. Only 40s is required by direct treatment to achieve 100% killing of E-coli. On the other hand, indirect treatment has inactivated 50% of the E-coli in 40s. In this study, direct and indirect effect of APPNJ to the E-coli can be observed which can be utilized into sterilization of bio-compatible material applications.

  19. Atmospheric-pressure plasma decontamination/sterilization chamber

    Energy Technology Data Exchange (ETDEWEB)

    Herrmann, Hans W. (Los Alamos, NM); Selwyn, Gary S. (Los Alamos, NM)

    2001-01-01

    An atmospheric-pressure plasma decontamination/sterilization chamber is described. The apparatus is useful for decontaminating sensitive equipment and materials, such as electronics, optics and national treasures, which have been contaminated with chemical and/or biological warfare agents, such as anthrax, mustard blistering agent, VX nerve gas, and the like. There is currently no acceptable procedure for decontaminating such equipment. The apparatus may also be used for sterilization in the medical and food industries. Items to be decontaminated or sterilized are supported inside the chamber. Reactive gases containing atomic and metastable oxygen species are generated by an atmospheric-pressure plasma discharge in a He/O.sub.2 mixture and directed into the region of these items resulting in chemical reaction between the reactive species and organic substances. This reaction typically kills and/or neutralizes the contamination without damaging most equipment and materials. The plasma gases are recirculated through a closed-loop system to minimize the loss of helium and the possibility of escape of aerosolized harmful substances.

  20. Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Robert F. Hicks; Hans W. Herrmann

    2003-12-15

    The purpose of this project was to demonstrate a practical, environmentally benigh technology for the surface decontamination and decommissioning of radioactive waste. A low temperature, atmospheric pressure plasma has been developed with initial support from the DOE, Environmental Management Sciences Program. This devise selectively etches radioactive metals from surfaces, rendering objects radiation free and suitable for decommissioning. The volatile reaction products are captured on filters, which yields a tremendous reduction in the volume of the waste. The technology shows a great potential for accelerating the clean-up effort for the equipment and structures contaminated with radioactive materials within the DOE complex. The viability of this technology has been demonstrated by selectively and rapidly stripping uranium from stainless steel surfaces at low temperature. Studies on uranium oxide have shown that etch rates of 4.0 microns per minute can be achieved at temperature below 473 K. Over the past three years, we have made numerous improvements in the design of the atmospheric pressure plasma source. We are now able to scale up the plasma source to treat large surface areas.

  1. Observations and Modeling of Plasma Waves in the Solar Atmosphere

    Science.gov (United States)

    Liu, W.; Ofman, L.; Downs, C.

    2016-12-01

    The solar atmosphere, especially the extended corona, provides rich observations of magnetohydrodynamic (MHD) waves and plasma waves in general. Such waves can be used as seismological tools to probe the physical conditions of the medium in which they travel, such as the coronal magnetic field and plasma parameters. Recent high-resolution imaging and spectroscopic observations in extreme ultraviolet (EUV) by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) and in UV by the Interface Region Imaging Spectrograph (IRIS) have opened a new chapter in understanding these waves and in utilizing them for coronal seismology. We will review such new observations of two intimately related phenomena - global EUV waves (so-called "EIT waves") associated with coronal mass ejections (CMEs) and quasi-periodic, fast-mode magnetosonic wave trains associated with flares. We will focus on the generation and propagation of global EUV waves and their interaction with coronal structures, as well as the correlation of AIA-detected fast-mode wave trains with flare pulsations seen from radio to hard X-ray wavelengths. We will also present recent MHD modeling efforts in reproducing these waves using realistic, observationally-driven simulations. We will discuss the roles of such waves in energy transport within the solar atmosphere and in their associated CME/flare eruptions.

  2. Langmuir probe diagnostics of an atmospheric pressure, vortex-stabilized nitrogen plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Prevosto, L.; Mancinelli, B. R. [Grupo de Descargas Electricas, Departamento Ingenieria Electromecanica, Facultad Regional Venado Tuerto (UTN), Laprida 651, (2600) Venado Tuerto, Santa Fe (Argentina); Kelly, H. [Grupo de Descargas Electricas, Departamento Ingenieria Electromecanica, Facultad Regional Venado Tuerto (UTN), Laprida 651, (2600) Venado Tuerto, Santa Fe (Argentina) and Instituto de Fisica del Plasma (CONICET), Departamento de Fisica, Facultad de Ciencias Exactas y Naturales UBA Ciudad Universitaria Pab. I, (1428) Buenos Aires (Argentina)

    2012-09-15

    Langmuir probe measurements in an atmospheric pressure direct current (dc) plasma jet are reported. Sweeping probes were used. The experiment was carried out using a dc non-transferred arc torch with a rod-type cathode and an anode of 5 mm diameter. The torch was operated at a nominal power level of 15 kW with a nitrogen flow rate of 25 Nl min{sup -1}. A flat ion saturation region was found in the current-voltage curve of the probe. The ion saturation current to a cylindrical probe in a high-pressure non local thermal equilibrium (LTE) plasma was modeled. Thermal effects and ionization/recombination processes inside the probe perturbed region were taken into account. Averaged radial profiles of the electron and heavy particle temperatures as well as the electron density were obtained. An electron temperature around 11 000 K, a heavy particle temperature around 9500 K and an electron density of about 4 Multiplication-Sign 10{sup 22} m{sup -3}, were found at the jet centre at 3.5 mm downstream from the torch exit. Large deviations from kinetic equilibrium were found throughout the plasma jet. The electron and heavy particle temperature profiles showed good agreement with those reported in the literature by using spectroscopic techniques. It was also found that the temperature radial profile based on LTE was very close to that of the electrons. The calculations have shown that this method is particularly useful for studying spraying-type plasma jets characterized by electron temperatures in the range 9000-14 000 K.

  3. Elevated Temperature Solid Particle Erosion Performance of Plasma-Sprayed Co-based Composite Coatings with Additions of Al2O3 and CeO2

    Science.gov (United States)

    Nithin, H. S.; Desai, Vijay; Ramesh, M. R.

    2017-09-01

    In this paper, investigation into solid particle erosion behavior of atmospheric plasma-sprayed composite coating of CoCrAlY reinforced with Al2O3 and CeO2 oxides on Superni 76 at elevated temperature of 600 °C is presented. Alumina particles are used as erodent at two impact angles of 30° and 90°. The microstructure, porosity, hardness, toughness and adhesion properties of the as-sprayed coatings are studied. The effects of temperature and phase transformation in the coatings during erosion process are analyzed using XRD and EDS techniques. Optical profilometer is used for accurate elucidation of erosion volume loss. CoCrAlY/CeO2 coating showed better erosion resistance with a volume loss of about 50% of what was observed in case of CoCrAlY/Al2O3/YSZ coating. Lower erosion loss is observed at 90° as compared to 30° impact angle. The erosion mechanism evaluated using SEM micrograph revealed that the coatings experienced ductile fracture exhibiting severe deformation with unusual oxide cracks. Reinforced metal oxides provide shielding effect for erodent impact, enabling better erosion resistance. The oxidation of the coating due to high-temperature exposure reforms erosion process into oxidation-modified erosion process.

  4. Elevated Temperature Solid Particle Erosion Performance of Plasma-Sprayed Co-based Composite Coatings with Additions of Al2O3 and CeO2

    Science.gov (United States)

    Nithin, H. S.; Desai, Vijay; Ramesh, M. R.

    2017-11-01

    In this paper, investigation into solid particle erosion behavior of atmospheric plasma-sprayed composite coating of CoCrAlY reinforced with Al2O3 and CeO2 oxides on Superni 76 at elevated temperature of 600 °C is presented. Alumina particles are used as erodent at two impact angles of 30° and 90°. The microstructure, porosity, hardness, toughness and adhesion properties of the as-sprayed coatings are studied. The effects of temperature and phase transformation in the coatings during erosion process are analyzed using XRD and EDS techniques. Optical profilometer is used for accurate elucidation of erosion volume loss. CoCrAlY/CeO2 coating showed better erosion resistance with a volume loss of about 50% of what was observed in case of CoCrAlY/Al2O3/YSZ coating. Lower erosion loss is observed at 90° as compared to 30° impact angle. The erosion mechanism evaluated using SEM micrograph revealed that the coatings experienced ductile fracture exhibiting severe deformation with unusual oxide cracks. Reinforced metal oxides provide shielding effect for erodent impact, enabling better erosion resistance. The oxidation of the coating due to high-temperature exposure reforms erosion process into oxidation-modified erosion process.

  5. Searching for order in atmospheric pressure plasma jets

    Science.gov (United States)

    Schäfer, Jan; Sigeneger, Florian; Šperka, Jiří; Rodenburg, Cornelia; Foest, Rüdiger

    2018-01-01

    The self-organized discharge behaviour occurring in a non-thermal radio-frequency plasma jet in rare gases at atmospheric pressure was investigated. The frequency of the azimuthal rotation of filaments in the active plasma volume and their inclination were measured along with the gas temperature under varying discharge conditions. The gas flow and heating were described theoretically by a three-dimensional hydrodynamic model. The rotation frequencies obtained by both methods qualitatively agree. The results demonstrate that the plasma filaments forming an inclination angle α with the axial gas velocity u z are forced to a transversal movement with the velocity {u}φ =\\tan (α )\\cdot {u}z, which is oriented in the inclination direction. Variations of {u}φ in the model reveal that the observed dynamics minimizes the energy loss due to convective heat transfer by the gas flow. The control of the self-organization regime motivates the application of the plasma jet for precise and reproducible material processing.

  6. Plasma Spraying and Characterization of Tungsten Carbide-Cobalt Coatings by the Water-Stabilized System WSP

    Directory of Open Access Journals (Sweden)

    Pavel Ctibor

    2009-01-01

    Full Text Available Tungsten carbide-cobalt powders (WC-17wt% Co were plasma sprayed by a water-stabilized system WSP. Experiments with variable feeding distances and spray distances were carried out. Thinner coatings were deposited on carbon steel substrates and thicker coatings on stainless steel substrates to compare different cooling conditions. Basic characterization of coatings was done by XRD, SEM, and light microscopy plus image analysis. Microhardness was measured on polished cross-sections. The main focus of investigation was resistance against wear in dry as well as wet conditions. The appropriate tests were performed with set-ups based on ASTM G65 and G75, respectively. The influence of spray parameters onto coating wear performance was observed. The results of mechanical tests were discussed in connection with changes of phase composition and with the quality of the coating's microstructure. The results show that for obtaining the best possible WC-17Co coating with WSP process, from the viewpoint of wear resistance, the desired parameters combination is long feeding distance combined with short spray distance.

  7. Atmospheric pressure plasma treatment of glassy carbon for adhesion improvement

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Mortensen, Henrik Junge; Stenum, Bjarne

    2007-01-01

    density increased with the plasma treatments. Adhesion test of the treated glassy carbon covered with cured epoxy showed cohesive failure, indicating strong bonding after the treatments. This is in contrast to the adhesion tests of untreated samples where the epoxy readily peeled off the glassy carbon.......Glassy carbon plates were treated with an atmospheric pressure dielectric barrier discharge (DBD). He gas, gas mixtures of He and reactive gases such as O2, CO2 and NH3, Ar gas and Ar/NH3 gas mixture were used as treatment gases. The oxygen and nitrogen contents on the surface as well as defect...

  8. Biomedical Applications of the Cold Atmospheric Plasma: Cell Responses

    Science.gov (United States)

    Volotskova, Olga

    Current breakthrough research on cold atmospheric plasma (CAP) demonstrates that CAP has great potential in various areas, including medicine and biology, thus providing a new tool for living tissue treatment. Depending on the configuration the cold plasma sources can be used in the following areas: wound healing, skin diseases, hospital hygiene, sterilization, antifungal treatments, dental care, cosmetics targeted cell/tissue removal, and cancer treatments. This dissertation is focused on the studies of biomedical applications of cold atmospheric plasma jet based on helium flow and resultant cell responses to the cold plasma treatment. The studies were carried out on extra-cellular and intra-cellular levels in vitro. The main practical applications are wound healing and alternative to existing cancer therapy methods, areas of great interest and significant challenges. The CAP jet was built in the Micropropulsion and Nanotechnology Laboratory of Dr. Michael Keidar, as a part of multidisciplinary collaboration with the GW Medical School (Dr. M.A. Stepp) concerned with plasma medicine and bioengineering studies. Normal and cancer cells have two fundamental behavioral properties, proliferation and motility, which can be evaluated through cell migration rates and cell cycle progression. Various microscopic, spectroscopic and flow cytometry techniques were used to characterize cell responses to the cold plasma treatment. It was found that CAP effect on the cells is localized within the area of the treatment (of around ˜ 5mm in diameter). The migration rates of the normal skin cells can be reduced up to ˜ 40%. However, depending on the cell type the required treatment time is different, thus differential treatment of various cells presented in tissue is possible. The CAP effect on the migration was explained through the changes of the cell surface proteins/integrins. It was also found that normal and cancer cells respond differently to the CAP treatment under the same

  9. Effect of Sulfur Acid Corrosion on the Luminescent Intensity of Plasma-Sprayed YAG:Ce Coatings

    Science.gov (United States)

    Wang, Weize; Zeng, Peng; Wang, Hehui; Yu, Jingye; Wu, Liangmin

    2017-01-01

    In order to monitor the corrosion condition of components, plasma-sprayed YAG:Ce coating was prepared for the detection, which could develop the application of plasma spraying. The effect of sulfuric acid corrosion on the microstructure, phase composition and luminescence intensity of coatings was studied. The powder was synthesized by the high-temperature solid-state method. Microstructure and phases were characterized through using SEM and XRD, respectively. Effect of immersion time in the acid was studied on the luminescence intensity. It was found that the phase composition of the powder was dominated by YAG (Y3Al5O12). More pores could be observed in coatings with the increase in immersion time. Sprayed coatings mainly included phases of YAG and YAP (YAlO3). The position of the XRD peaks of coatings was changing during the immersion. The luminescence intensity showed the fluctuation tendency with the immersion time, which related to the coating porosity, phase composition and the migration of the diffract peak.

  10. Evaporation of Droplets in Plasma Spray-Physical Vapor Deposition Based on Energy Compensation Between Self-Cooling and Plasma Heat Transfer

    Science.gov (United States)

    Liu, Mei-Jun; Zhang, Meng; Zhang, Qiang; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2017-10-01

    In the plasma spray-physical vapor deposition process (PS-PVD), there is no obvious heating to the feedstock powders due to the free molecular flow condition of the open plasma jet. However, this is in contrast to recent experiments in which the molten droplets are transformed into vapor atoms in the open plasma jet. In this work, to better understand the heating process of feedstock powders in the open plasma jet of PS-PVD, an evaporation model of molten ZrO2 is established by examining the heat and mass transfer process of molten ZrO2. The results reveal that the heat flux in PS-PVD open plasma jet (about 106 W/m2) is smaller than that in the plasma torch nozzle (about 108 W/m2). However, the flying distance of molten ZrO2 in the open plasma jet is much longer than that in the plasma torch nozzle, so the heating in the open plasma jet cannot be ignored. The results of the evaporation model show that the molten ZrO2 can be partly evaporated by self-cooling, whereas the molten ZrO2 with a diameter heat transfer.

  11. Trends in surface engineering of biomaterials: atmospheric pressure plasma deposition of coatings for biomedical applications

    Science.gov (United States)

    da Ponte, G.; Sardella, E.; Fanelli, F.; D'Agostino, R.; Favia, P.

    2011-11-01

    Cold plasma processes for surface engineering of biomaterials and biomedical devices are traditionally performed at low pressure; more and more, though, surface modification plasma processes at atmospheric pressure are also gaining popularity. This short review is aimed to list briefly atmospheric pressure plasma processes reported, in the last decade, for adapting the surface of materials to the best interactions with cells, bacteria and biomolecules.

  12. Surface characterization and cytotoxicity analysis of plasma sprayed coatings on titanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Zia ur; Shabib, Ishraq [School of Engineering and Technology, Central Michigan University, Mount Pleasant, MI 48859 (United States); Science of Advanced Materials, Central Michigan University, Mount Pleasant, MI 48859 (United States); Haider, Waseem, E-mail: haide1w@cmich.edu [School of Engineering and Technology, Central Michigan University, Mount Pleasant, MI 48859 (United States); Science of Advanced Materials, Central Michigan University, Mount Pleasant, MI 48859 (United States)

    2016-10-01

    In the realm of biomaterials, metallic materials are widely used for load bearing joints due to their superior mechanical properties. Despite the necessity for long term metallic implants, there are limitations to their prolonged use. Naturally, oxides of titanium have low solubilities and form passive oxide film spontaneously. However, some inclusion and discontinuity spots in oxide film make implant to adopt the decisive nature. These defects heighten the dissolution of metal ions from the implant surface, which results in diminishing bio-integration of titanium implant. To increase the long-term metallic implant stability, surface modifications of titanium alloys are being carried out. In the present study, biomimetic coatings of plasma sprayed hydroxyapatite and titanium were applied to the surface of commercially pure titanium and Ti6Al4V. Surface morphology and surface chemistry were studied using scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Cyclic potentiodynamic polarization and electrochemical impedance spectroscopy were carried out in order to study their electrochemical behavior. Moreover, cytotoxicity analysis was conducted for osteoblast cells by performing MTS assay. It is concluded that both hydroxyapatite and titanium coatings enhance corrosion resistance and improve cytocompatibility. - Highlights: • Surface morphology and surface chemistry were studied using scanning electron microscopy and X-ray photoelectron spectroscopy. • The cyclic polarization tests revealed noticeable improvement towards the positive potentials for both Tip coatings. • CpTi-Hap and Ti6Al4V-Hap both demonstrate similar corrosion rate. • High cytotoxicity was observed for Mp when compared with Tip and Hap after 21 days of immersion. • Both Tip and Hap coatings promoted the osteoblast cell adhesion and exhibited stellar morphology.

  13. Vacuum Plasma Spray of CuCrNb Alloy for Advanced Liquid - Fuel Combustion Chambers

    Science.gov (United States)

    Zimmerman, Frank

    2000-01-01

    The copper-8 atomic percent chromium-4 atomic percent niobium (CuCrNb) alloy was developed by Glenn Research Center (formally Lewis Research Center) as an improved alloy for combustion chamber liners. In comparison to NARloy-Z, the baseline (as in Space Shuttle Main Engine) alloy for such liners, CuCrNb demonstrates mechanical and thermophysical properties equivalent to NARloy-Z, but at temperatures 100 C to 150 C (180 F to 270 F) higher. Anticipated materials related benefits include decreasing the thrust cell liner weight 5% to 20%, increasing the service life at least two fold over current combustion chamber design, and increasing the safety margins available to designers. By adding an oxidation and thermal barrier coating to the liner, the combustion chamber can operate at even higher temperatures. For all these benefits, however, this alloy cannot be formed using conventional casting and forging methods because of the levels of chromium and niobium, which exceed their solubility limit in copper. Until recently, the only forming process that maintains the required microstructure of CrNb intermetallics is powder metallurgy formation of a billet from powder stock, followed by extrusion. This severely limits its usefulness in structural applications, particularly the complex shapes required for combustion chamber liners. Vacuum plasma spray (VPS) has been demonstrated as a method to form structural articles including small combustion chambers from the CuCrNb alloy. In addition, an oxidation and thermal barrier layer can be formed integrally on the hot wall of the liner that improve performance and extend service life. This paper discusses the metallurgy and thermomechanical properties of VPS formed CuCrNb versus the baseline powder metallurgy process, and the manufacturing of small combustion chamber liners at Marshall Space Flight Center using the VPS process. The benefits to advanced propulsion initiatives of using VPS to fabricate combustion chamber liners

  14. Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Hiromasa [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Mizuno, Masaaki [Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Toyokuni, Shinya [Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Maruyama, Shoichi [Department of Nephrology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kodera, Yasuhiro [Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Terasaki, Hiroko [Department of Ophthalmology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Adachi, Tetsuo [Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University, 501-1196 Gifu (Japan); Kato, Masashi [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kikkawa, Fumitaka [Department of Obstetrics and Gynecology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Hori, Masaru [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2015-12-15

    Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established.

  15. Evaluation of the behavior of shrouded plasma spray coatings in the platen superheater of coal-fired boilers

    Science.gov (United States)

    Sidhu, Buta Singh; Prakash, S.

    2006-06-01

    Nickel- and cobalt-based coatings were formulated by a shrouded plasma spray process on boiler tube steels, namely, ASTM-SA210-grade A1 (GrA1), ASTM-SA213-T-11 (T11), and ASTM-SA213-T-22 (T22). The Ni-22Cr-10Al-1Y alloy powder was sprayed as a bond in each case before the final coating. The degradation behavior of the bared and coated steels was studied in the platen superheater of the coal-fired boiler. The samples were inserted through the soot blower dummy points with the help of stainless steel wires. The coatings were found to be effective in increasing resistance to degradation in the given boiler environment. The maximum protection was observed in the case of Stellite-6 (St-6) coating.

  16. Combustion of diesel spray injected into reacting atmosphere of propane-air homogeneous mixture

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J.-H.; Iida, N. [Keio Univ., Yokohama (Japan)

    2001-03-28

    The effects of each reaction stage (low-temperature reaction, high temperature reaction and post-combustion) of a homogeneous mixture (propane/air) on the ignition and combustion of a diesel spray were investigated using a rapid compression machine (RCM). The concentrations of formaldehyde (HCHO) and hydrogen peroxide (H{sub 2}O{sub 2}) were calculated in the low-temperature reaction using CHEMKIN. The correlation between soot formation and fuel injection timing was investigated in each reaction stage of the homogeneous mixture. When diesel fuel was injected during the low-temperature reactions, soot formation was more restrained than at any other reaction stage of the homogeneous mixture. (Author)

  17. Surface chemical changes of atmospheric pressure plasma treated rabbit fibres important for felting process

    Energy Technology Data Exchange (ETDEWEB)

    Štěpánová, Vlasta, E-mail: vstepanova@mail.muni.cz [Department of Physical Electronics, Faculty of Science Masaryk University, Kotlářská 2, 611 37 Brno (Czech Republic); Slavíček, Pavel; Stupavská, Monika; Jurmanová, Jana [Department of Physical Electronics, Faculty of Science Masaryk University, Kotlářská 2, 611 37 Brno (Czech Republic); Černák, Mirko [Department of Physical Electronics, Faculty of Science Masaryk University, Kotlářská 2, 611 37 Brno (Czech Republic); Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynská dolina F2, 842 48 Bratislava (Slovakia)

    2015-11-15

    Graphical abstract: - Highlights: • Rabbit fibres plasma treatment is an effective method for fibres modification. • Atmospheric pressure plasma treatment is able to affect fibres properties. • Surface changes on fibres after plasma treatment were analysed via SEM, ATR-FTIR, XPS. • Significant increase of fibres wettability after plasma treatment was observed. • Plasma treatment at atmospheric pressure can replace the chemical treatment of fibres. - Abstract: We introduce the atmospheric pressure plasma treatment as a suitable procedure for in-line industrial application of rabbit fibres pre-treatment. Changes of rabbit fibre properties due to the plasma treatment were studied in order to develop new technology of plasma-based treatment before felting. Diffuse Coplanar Surface Barrier Discharge (DCSBD) in ambient air at atmospheric pressure was used for plasma treatment. Scanning electron microscopy was used for determination of the fibres morphology before and after plasma treatment. X-ray photoelectron spectroscopy and attenuated total reflectance-Fourier transform infrared spectroscopy were used for evaluation of reactive groups. The concentration of carbon decreased and conversely the concentration of nitrogen and oxygen increased after plasma treatment. Aging effect of plasma treated fibres was also investigated. Using Washburn method the significant increase of fibres wettability was observed after plasma treatment. New approach of pre-treatment of fibres before felting using plasma was developed. Plasma treatment of fibres at atmospheric pressure can replace the chemical method which consists of application of strong acids on fibres.

  18. Deposition of silica protected luminescent layers of Eu:GdVO{sub 4} nanoparticles assisted by atmospheric pressure plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Moretti, Elisa, E-mail: elisa.moretti@unive.it [Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari Venezia, INSTM Venice Research Unit, Via Torino 155/B, 30172 Mestre, Venezia (Italy); Pizzol, Giorgia [Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari Venezia, INSTM Venice Research Unit, Via Torino 155/B, 30172 Mestre, Venezia (Italy); Fantin, Marina; Enrichi, Francesco; Scopece, Paolo [Nanofab-Veneto Nanotech, Via delle Industrie 5, 30175 Marghera, Venezia (Italy); Nuñez, Nuria O.; Ocaña, Manuel [Instituto de Ciencia de Materiales de Sevilla, CSIC-US, Americo Vespucio 49, 41092, Isla de la Cartuja, Sevilla (Spain); Benedetti, Alvise [Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari Venezia, INSTM Venice Research Unit, Via Torino 155/B, 30172 Mestre, Venezia (Italy); Polizzi, Stefano [Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari Venezia, INSTM Venice Research Unit, Via Torino 155/B, 30172 Mestre, Venezia (Italy); Centro di Microscopia Elettronica “Giovanni Stevanato”, Università Ca' Foscari Venezia, Via Torino 155/B, 30172 Mestre, Venezia (Italy)

    2016-01-01

    Eu:GdVO{sub 4} nanophosphors with an average size of 60 nm, synthesized by a facile solvothermal method, were deposited on monocrystalline silicon wafers by a spray-coating technique with artworks anti-counterfeiting applications in mind. Atmospheric pressure plasma jet (APPJ) was used to deposit a silica-based layer on top of the nanometric luminescent layer, in order to improve its adhesion to the substrate and to protect it from the environment. The nanophosphors were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Coating composition was investigated by Fourier transform infrared spectroscopy (FT-IR) and its morphology was characterized by scanning electron microscopy (FEG-SEM). The film thickness was evaluated by means of ellipsometry and adhesion was estimated by a peeling test. Luminescent properties of the nanophosphors deposited and fixed on silicon wafers were also measured. The whole layer resulted well-adhered to the silicon substrate, transparent and undetectable in the presence of visible light, but easily activated by UV light source. - Highlights: • Luminescent films were obtained by spray deposition of Eu:GdVO{sub 4} nanophosphors. • Plasma jet deposition of SiO{sub 2} fixed the nanophosphors on the substrate. • Optical properties of nanophosphors were preserved after deposition-fixing process. • Films well-adhered to the substrate, even after a scotch tape peeling test and a scratch test.

  19. Use of Atmospheric-Pressure Plasma Jet for Polymer Surface Modification: An Overview

    Energy Technology Data Exchange (ETDEWEB)

    Kuettner, Lindsey A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-03-16

    Atmospheric-pressure plasma jets (APPJs) are playing an increasingly important role in materials processing procedures. Plasma treatment is a useful tool to modify surface properties of materials, especially polymers. Plasma reacts with polymer surfaces in numerous ways thus the type of process gas and plasma conditions must be explored for chosen substrates and materials to maximize desired properties. This report discusses plasma treatments and looks further into atmospheric-pressure plasma jets and the effects of gases and plasma conditions. Following the short literature review, a general overview of the future work and research at Los Alamos National Laboratory (LANL) is discussed.

  20. Helium atmospheric pressure plasma jets touching dielectric and metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Norberg, Seth A., E-mail: norbergs@umich.edu; Johnsen, Eric, E-mail: ejohnsen@umich.edu [Department of Mechanical Engineering, University of Michigan, 2350 Hayward Street, Ann Arbor, Michigan 48109-2125 (United States); Kushner, Mark J., E-mail: mjkush@umich.edu [Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Avenue, Ann Arbor, Michigan 48109-2122 (United States)

    2015-07-07

    Atmospheric pressure plasma jets (APPJs) are being investigated in the context plasma medicine and biotechnology applications, and surface functionalization. The composition of the surface being treated ranges from plastics, liquids, and biological tissue, to metals. The dielectric constant of these materials ranges from as low as 1.5 for plastics to near 80 for liquids, and essentially infinite for metals. The electrical properties of the surface are not independent variables as the permittivity of the material being treated has an effect on the dynamics of the incident APPJ. In this paper, results are discussed from a computational investigation of the interaction of an APPJ incident onto materials of varying permittivity, and their impact on the discharge dynamics of the plasma jet. The computer model used in this investigation solves Poisson's equation, transport equations for charged and neutral species, the electron energy equation, and the Navier-Stokes equations for the neutral gas flow. The APPJ is sustained in He/O{sub 2} = 99.8/0.2 flowing into humid air, and is directed onto dielectric surfaces in contact with ground with dielectric constants ranging from 2 to 80, and a grounded metal surface. Low values of relative permittivity encourage propagation of the electric field into the treated material and formation and propagation of a surface ionization wave. High values of relative permittivity promote the restrike of the ionization wave and the formation of a conduction channel between the plasma discharge and the treated surface. The distribution of space charge surrounding the APPJ is discussed.

  1. Cluster model of amorphized particles formation by plasma spraying of metallic powder

    Science.gov (United States)

    Barakhtin, Boris K.; Nesterova, E. V.

    1999-05-01

    Multifunctional coatings from materials with amorphized microcrystalline or nano-phase structure cause a considerable scientific and practical interest. With their help it is to manufacture heat resistant neutralizers of harmful ejections, to produce ecologically clean sources of electric current, to design electromagnetic protective shields and to fabricate a lot of other technical products. The variety of application and a unique complex of operating characteristics (ductility, strength, magnetic and chemical properties) are governed by the basic peculiarity of material in amorphized state - its thermodynamic instability. In comparison with traditional thermodynamically equilibrium metallic alloys, the kinetics of structure changes in amorphous materials is quite different. Thus, it is suggested, that they have peculiar defects (phasonics) which are not typical of materials in crystalline state, they have no translational symmetry and elementary cells. In the process of coatings forming with non-equilibrium structure states can be realized in them, which are characterized by a fluctuation type of origin, entropy export, appearance of space or temporary symmetry uncertainty of the transition direction 'order $ARLR disorder' in bifurcation points. The aforesaid explains a great scientific (not only practical) interest in the structure study of disordered medium. Functional coatings with amorphized, nano- and microcrystalline structure components formed on copper substrate by plasma spraying of dispersed (to 50 mcm) Ni-Al powder. According to the constitutional diagram it was expected to obtain a mixture from equilibrium intermetallide phases NiAl3 + Ni2Al3. The experimental results and investigations performed by X-ray structure, X-ray spectrum and electron microscopy techniques have shown it is possible to obtain phases of variable composition (Ni)m(Al)n with Ni content from 25 to 75 vol.%, including NiAl. It turned out that in the process of spraying the

  2. Novel atmospheric plasma enhanced chitosan nanofiber/gauze composite wound dressings

    Science.gov (United States)

    Electrospun chitosan nanofibers were deposited onto atmospheric plasma treated cotton gauze to create a novel composite bandage with higher adhesion, better handling properties, enhanced bioactivity, and moisture management. Plasma treatment of the gauze substrate was performed to improve the durabi...

  3. Modification of vacuum plasma sprayed tungsten coating on reduced activation ferritic/martensitic steels by friction stir processing

    Energy Technology Data Exchange (ETDEWEB)

    Tanigawa, Hiroyasu, E-mail: tanigawa.hiroyasu@jaea.go.jp [Fusion Research and Development Directorate, Japan Atomic Energy Agency, Rokkasho, Aomori (Japan); Ozawa, Kazumi [Fusion Research and Development Directorate, Japan Atomic Energy Agency, Rokkasho, Aomori (Japan); Morisada, Yoshiaki [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka (Japan); Noh, Sanghoon [Fusion Research and Development Directorate, Japan Atomic Energy Agency, Rokkasho, Aomori (Japan); Nuclear Material Development Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Fujii, Hidetoshi [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka (Japan)

    2015-10-15

    Highlights: • Friction stir processing (FSP) was applied on vacuum plasma spray (VPS) W to improve its low thermal conductivity and weakness due to high porosity. • FSP can achieve significant improvement both in mechanical and thermal properties of VPS-W coating. • It was indicated that the double pass FSP at 600 rpm/50 mm/min/2 ton on VPS-W show the most dense microstructure and hardest mechanical property. • Hardness test over FSPed VPS-W layer revealed that the hardness of W becomes higher than that of bulk W. • The thermal conductivity of double pass FSPed VPS-W was about 80% of bulk W at 200 °C, and it becomes equivalent to that of bulk W over 800 °C. - Abstract: Tungsten (W) is the primary candidate material as a plasma facing material in fusion devices, as for its high melting temperature, good thermal conductivity and low sputtering rate, and vacuum plasma spray (VPS) technique is preferred as it is applicable for large area without brittle interlayer, but the thermal conductivity of W layer is very poor, and easy to detach, mainly caused by its porous structure. W Friction stir processing (FSP) was applied on VPS-W to improve these poor properties, and it was suggested that FSP can contribute to significant improvement in both mechanical and thermal properties of the VPS-W coating.

  4. A systematic review on the long-term success of calcium phosphate plasma-spray-coated dental implants.

    Science.gov (United States)

    van Oirschot, B A J A; Bronkhorst, E M; van den Beucken, J J J P; Meijer, G J; Jansen, J A; Junker, R

    2016-09-01

    The objectives of the current review were (1) to systematically appraise, and (2) to evaluate long-term success data of calcium phosphate (CaP) plasma-spray-coated dental implants in clinical trials with at least 5 years of follow-up. To describe the long-term efficacy of functional implants, the outcome variables were (a) percentage annual complication rate (ACR) and (b) cumulative success rate (CSR), as presented in the selected articles. The electronic search yielded 645 titles. On the basis of the inclusion criteria, 8 studies were finally included. The percentage of implants in function after the first year was estimated to be 98.4 % in the maxilla and 99.2 % in the mandible. The estimates of the weighted mean ACR-percentage increased over the years up to 2.6 (SE 0.7) during the fifth year of function for the maxilla and to 9.4 (SE 8.4) for the mandible in the tenth year of function. After 10 years, the mean percentage of successful implants was estimated to be 71.1 % in the maxilla and 72.2 % in the mandible. The estimates seem to confirm the proposed, long-term progressive bone loss pattern of CaP-ceramic-coated dental implants. Within the limits of this meta-analytic approach to the literature, we conclude that: (1) published long-term success data for calcium phosphate plasma-spray-coated dental implants are limited, (2) comparison of the data is difficult due to differences in success criteria among the studies, and (3) long-term CSRs demonstrate very weak evidence for progressive complications around calcium phosphate plasma-spray-coated dental implants.

  5. Prediction and optimization of process variables to maximize the Young's modulus of plasma sprayed alumina coatings on AZ31B magnesium alloy

    Directory of Open Access Journals (Sweden)

    D. Thirumalaikumarasamy

    2017-03-01

    Full Text Available Like other manufacturing techniques, plasma spraying has also a non-linear behavior because of the contribution of many coating variables. This characteristic results in finding optimal factor combination difficult. Subsequently, the issue can be solved through effective and strategic statistical procedures integrated with systematic experimental data. Plasma spray parameters such as power, stand-off distance and powder feed rate have significant influence on coating characteristics like Young's modulus. This paper presents the use of statistical techniques in specifically response surface methodology (RSM, analysis of variance, and regression analysis to develop empirical relationship to predict Young's modulus of plasma-sprayed alumina coatings. The developed empirical relationships can be effectively used to predict Young's modulus of plasma-sprayed alumina coatings at 95% confidence level. Response graphs and contour plots were constructed to identify the optimum plasma spray parameters to attain maximum Young's modulus in alumina coatings. A linear regression relationship was established between porosity and Young's modulus of the alumina coatings.

  6. Atmospheric Pressure Plasma-Electrospin Hybrid Process for Protective Applications

    Science.gov (United States)

    Vitchuli Gangadharan, Narendiran

    2011-12-01

    Chemical and biological (C-B) warfare agents like sarin, sulfur mustard, anthrax are usually dispersed into atmosphere in the form of micro aerosols. They are considered to be dangerous weapon of mass destruction next to nuclear weapons. The airtight protective clothing materials currently available are able to stop the diffusion of threat agents but not good enough to detoxify them, which endangers the wearers. Extensive research efforts are being made to prepare advanced protective clothing materials that not only prevent the diffusion of C-B agents, but also detoxify them into harmless products thus ensuring the safety and comfort of the wearer. Electrospun nanofiber mats are considered to have effective filtration characteristics to stop the diffusion of submicron level particulates without sacrificing air permeability characteristics and could be used in protective application as barrier material. In addition, functional nanofibers could be potentially developed to detoxify the C-B warfare threats into harmless products. In this research, electrospun nanofibers were deposited on fabric surface to improve barrier efficiency without sacrificing comfort-related properties of the fabrics. Multi-functional nanofibers were fabricated through an electrospinning-electrospraying hybrid process and their ability to detoxify simulants of C-B agents was evaluated. Nanofibers were also deposited onto plasma-pretreated woven fabric substrate through a newly developed plasma-electrospinning hybrid process, to improve the adhesive properties of nanofibers on the fabric surface. The nanofiber adhesion and durability properties were evaluated by peel test, flex and abrasion resistance tests. In this research work, following tasks have been carried out: i) Controlled deposition of nanofiber mat onto woven fabric substrate Electrospun Nylon 6 fiber mats were deposited onto woven 50/50 Nylon/Cotton fabric with the motive of making them into protective material against submicron

  7. Non-parabolic isothermal oxidation kinetics of low pressure plasma sprayed MCrAlY bond coat

    Science.gov (United States)

    Zhang, Bang-Yan; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2017-06-01

    The non-parabolic isothermal oxidation kinetics of low pressure plasma sprayed MCrAlY bond coat was investigated. To qualitatively explain the abnormal growth phenomenon of thermally grown oxides (TGO), the changes that occurred to their microstructure during the oxidation process were studied. Based on these observations, a modified model was developed to understand and quantitatively predict the non-parabolic oxidation and growth kinetics of TGO. This modified model, which fits well with experimental results, provides a novel method to quantitatively predict the long-term growth behaviour of TGO, and thereby benefits the development of long-life and highly reliable thermal barrier coatings.

  8. Use of Atmospheric Pressure Cold Plasma for Meat Industry.

    Science.gov (United States)

    Lee, Juri; Lee, Cheol Woo; Yong, Hae In; Lee, Hyun Jung; Jo, Cheorun; Jung, Samooel

    2017-01-01

    Novel, effective methods to control and prevent spoilage and contamination by pathogenic microorganisms in meat and meat products are in constant demand. Non-thermal pasteurization is an ideal method for the preservation of meat and meat products because it does not use heat during the pasteurization process. Atmospheric pressure cold plasma (APCP) is a new technology for the non-thermal pasteurization of meat and meat products. Several recent studies have shown that APCP treatment reduces the number of pathogenic microorganisms in meat and meat products. Furthermore, APCP treatment can be used to generate nitrite, which is an essential component of the curing process. Here, we introduce the effectiveness of APCP treatment as a pasteurization method and/or curing process for use in the meat and meat product processing industry.

  9. Surface Treatment of PET Nonwovens with Atmospheric Plasma

    Science.gov (United States)

    Li, Shufang

    2013-01-01

    In this study, polyethylene-terephthalate (PET) nonwovens are treated using an atmospheric plasma and the effects of the treatment time, treatment power and discharge distance on the ability of water-penetration into the nonwovens are investigated. The result indicates that the method can improve the wettability of PET nonwovens remarkably, but the aging decay of the sample's wettability is found to be notable as a function of the storage time after treatment due to the internal rotation of the single bond of surface macromolecules. As shown by SEM and XPS analysis, the etching and surface reaction are significant, and water-penetration weight is found to increase remarkably with the increasing power. This variation can be attributed to momentum transfer and enhanced higher-energy particle excitation.

  10. Influence of in-flight particle state diagnostics on properties of plasma sprayed YSZ-CeO2 nanocomposite coatings

    Directory of Open Access Journals (Sweden)

    S. Mantry

    2014-07-01

    Full Text Available This article describes the influence of controlling in-flight hot particle characteristics on properties of plasma sprayed nanostructured yttria stabilized zirconia (YSZ coatings. This article depicts dependence of adhesion strength of as-sprayed nanostructured YSZ coatings on particle temperature, velocity and size of the splat prior to impact on the metallic substrate. Particle temperature measurement is based on two-color pyrometry and particle velocities are measured from the length of the particle traces during known exposure times. The microstructure and adhesion strength of as-sprayed nano-YSZ coatings were studied. Field emission scanning electron microscopy results revealed that morphology of coating exhibits bimodal microstructure consisting of nano-zones reinforced in the matrix of fully melted particles. The coating adhesion strength is noticed to be greatly affected by the melting state of agglomerates. Maximum adhesion strength of 42.39 MPa has been experimentally found out by selecting optimum levels of particle temperature and velocity. The enhanced bond strength of nano-YSZ coating may be attributed to higher interfacial toughness due to cracks being interrupted by adherent nano-zones.

  11. Effects of dietary spray-dried plasma protein on sow productivity during lactation.

    Science.gov (United States)

    Frugé, E D; Roux, M L; Lirette, R D; Bidner, T D; Southern, L L; Crenshaw, J D

    2009-03-01

    Seventy-two primiparous and multiparous sows (36 per dietary treatment) farrowed in 4 groups were used to evaluate the effects of spray-dried plasma protein (SDP) on sow and litter performance during lactation. Dietary lactation treatments consisted of a corn-soybean meal control and a corn-soybean meal diet containing 0.5% SDP. Both diets were formulated to contain 1.0% total Lys and 3.46 Mcal/kg of ME and were fed from d 107 +/- 1.2 of gestation to weaning. Sows were allotted to dietary treatment based on breed, parity, and the date of d 107 of gestation. Litters were standardized within diet, and pigs were weaned at an average age of 19 +/- 2.1 d. Sows were fed 3 times daily during lactation. After weaning, sows were fed a common gestation diet and checked twice daily for estrus. Sows were grouped by parity (young sows, sows, >3) for statistical analysis. The data were analyzed as a 2 x 2 factorial arrangement of treatments; the factors were parity (3) and SDP (0 or 0.5%). Treatment differences were considered significant at P sows had a greater BW on d 107 of gestation, on d 1 postfarrowing, and at weaning; greater lactation ADFI; and greater litter BW after cross-fostering, but pig survival to weaning was decreased. Sows fed SDP had a greater gestation interval, litter BW at weaning, and litter ADG, with 1 less lactation day. The effect of SDP addition was dependent on sow parity, as noted by numerous SDP x parity interactions. The addition of SDP increased lactation ADFI in mature sows but decreased ADFI in young sows. Mature sows fed SDP had a greater number of pigs weaned per litter, litter and pig weaning weights, pig survival to weaning, and number of pigs weaned per litter weighing more than 3.6 kg, but the SDP diet had little to no effect on these responses in young sows. Subsequent farrowing data were collected, but no dietary treatment effects (P > 0.10) were observed. The results of this research indicate that SDP increased productivity of sows in

  12. Plasma penetration depth and mechanical properties of atmospheric plasma-treated 3D aramid woven composites

    Science.gov (United States)

    Chen, X.; Yao, L.; Xue, J.; Zhao, D.; Lan, Y.; Qian, X.; Wang, C. X.; Qiu, Y.

    2008-12-01

    Three-dimensional aramid woven fabrics were treated with atmospheric pressure plasmas, on one side or both sides to determine the plasma penetration depth in the 3D fabrics and the influences on final composite mechanical properties. The properties of the fibers from different layers of the single side treated fabrics, including surface morphology, chemical composition, wettability and adhesion properties were investigated using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), contact angle measurement and microbond tests. Meanwhile, flexural properties of the composites reinforced with the fabrics untreated and treated on both sides were compared using three-point bending tests. The results showed that the fibers from the outer most surface layer of the fabric had a significant improvement in their surface roughness, chemical bonding, wettability and adhesion properties after plasma treatment; the treatment effect gradually diminished for the fibers in the inner layers. In the third layer, the fiber properties remained approximately the same to those of the control. In addition, three-point bending tests indicated that the 3D aramid composite had an increase of 11% in flexural strength and 12% in flexural modulus after the plasma treatment. These results indicate that composite mechanical properties can be improved by the direct fabric treatment instead of fiber treatment with plasmas if the fabric is less than four layers thick.

  13. Plasma penetration depth and mechanical properties of atmospheric plasma-treated 3D aramid woven composites

    Energy Technology Data Exchange (ETDEWEB)

    Chen, X.; Yao, L.; Xue, J.; Zhao, D.; Lan, Y.; Qian, X. [Key Laboratory of Textile Science and Technology, Donghua University, Ministry of Education (China); Department of Textile Materials Science and Product Design, College of Textiles, Donghua University, Shanghai 201620 (China); Wang, C.X. [Key Laboratory of Textile Science and Technology, Donghua University, Ministry of Education (China); Department of Textile Materials Science and Product Design, College of Textiles, Donghua University, Shanghai 201620 (China); College of Textiles and Clothing, Yancheng Institute of Technology, Jiangsu 224003 (China); Qiu, Y. [Key Laboratory of Textile Science and Technology, Donghua University, Ministry of Education (China); Department of Textile Materials Science and Product Design, College of Textiles, Donghua University, Shanghai 201620 (China)], E-mail: ypqiu@dhu.edu.cn

    2008-12-30

    Three-dimensional aramid woven fabrics were treated with atmospheric pressure plasmas, on one side or both sides to determine the plasma penetration depth in the 3D fabrics and the influences on final composite mechanical properties. The properties of the fibers from different layers of the single side treated fabrics, including surface morphology, chemical composition, wettability and adhesion properties were investigated using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), contact angle measurement and microbond tests. Meanwhile, flexural properties of the composites reinforced with the fabrics untreated and treated on both sides were compared using three-point bending tests. The results showed that the fibers from the outer most surface layer of the fabric had a significant improvement in their surface roughness, chemical bonding, wettability and adhesion properties after plasma treatment; the treatment effect gradually diminished for the fibers in the inner layers. In the third layer, the fiber properties remained approximately the same to those of the control. In addition, three-point bending tests indicated that the 3D aramid composite had an increase of 11% in flexural strength and 12% in flexural modulus after the plasma treatment. These results indicate that composite mechanical properties can be improved by the direct fabric treatment instead of fiber treatment with plasmas if the fabric is less than four layers thick.

  14. The solvation of electrons by an atmospheric-pressure plasma

    Science.gov (United States)

    Rumbach, Paul; Bartels, David M.; Sankaran, R. Mohan; Go, David B.

    2015-01-01

    Solvated electrons are typically generated by radiolysis or photoionization of solutes. While plasmas containing free electrons have been brought into contact with liquids in studies dating back centuries, there has been little evidence that electrons are solvated by this approach. Here we report direct measurements of solvated electrons generated by an atmospheric-pressure plasma in contact with the surface of an aqueous solution. The electrons are measured by their optical absorbance using a total internal reflection geometry. The measured absorption spectrum is unexpectedly blue shifted, which is potentially due to the intense electric field in the interfacial Debye layer. We estimate an average penetration depth of 2.5±1.0 nm, indicating that the electrons fully solvate before reacting through second-order recombination. Reactions with various electron scavengers including H+, NO2−, NO3− and H2O2 show that the kinetics are similar, but not identical, to those for solvated electrons formed in bulk water by radiolysis. PMID:26088017

  15. Evaluation of Penicillium digitatum sterilization using non-equilibrium atmospheric pressure plasma by terahertz time-domain spectroscopy

    Science.gov (United States)

    Hiraoka, Takehiro; Ebizuka, Noboru; Takeda, Keigo; Ohta, Takayuki; Kondo, Hiroki; Ishikawa, Kenji; Kawase, Kodo; Ito, Masafumi; Sekine, Makoto; Hori, Masaru

    2011-10-01

    Recently, the plasma sterilization has attracted much attention as a new sterilization technique that takes the place of spraying agricultural chemicals. The conventional methods for sterilization evaluation, was demanded to culture the samples for several days after plasma treatment. Then, we focused on Terahertz time-domain spectroscopy (THz-TDS). At the THz region, vibrational modes of biological molecules and fingerprint spectra of biologically-relevant molecules were also observed. In this study, our purpose was measurement of the fingerprint spectrum of the Penicillium digitatum (PD) spore and establishment of sterilization method by THz-TDS. The sample was 40mg/ml PD spore suspensions which dropped on cover glass. The atmospheric pressure plasma generated under the conditions which Ar gas flow was 3slm, and alternating voltage of 6kV was applied. The samples were exposed the plasma from 10mm distance for 10 minutes. We could obtain the fingerprint spectrum of the PD spore from 0.5 to 0.9THz. This result indicated the possibility of in-situ evaluation for PD sterilization using THz-TDS.

  16. High heat loading properties of vacuum plasma spray tungsten coatings on reduced activation ferritic/martensitic steel

    Science.gov (United States)

    Tokunaga, K.; Hotta, T.; Araki, K.; Miyamoto, Y.; Fujiwara, T.; Hasegawa, M.; Nakamura, K.; Ezato, K.; Suzuki, S.; Enoeda, M.; Akiba, M.; Nagasaka, T.; Kasada, R.; Kimura, A.

    2013-07-01

    High density W coatings on reduced activation ferritic martensitic steel (RAF/M) have been produced by Vacuum Plasma Spraying technique (VPS) and heat flux experiments on them have been carried out to evaluate their possibility as a plasma-facing armor in a fusion device. In addition, quantitative analyses of temperature profile and thermal stress have been carried out using the finite element analysis (FEA) to evaluate its thermal properties. No cracks or exfoliation has been formed by steady state and cyclic heat loading experiments under heat loading at 700 °C of surface temperature. In addition, stress distribution and maximum stress between interface of VPS-W and RAF/M have been obtained by FEA. On the other hand, exfoliation has occurred at interlayer of VPS-W coatings near the interface between VPS-W and RAF/M at 1300 °C of surface temperature by cyclic heat loading.

  17. Comment on Nemchinsky's analysis of the 'rocket' effect under conditions of thermal plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Chen Xi [Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China)

    2007-07-07

    In a recent paper, Nemchinsky presents an analysis of the 'rocket' effect on the particle dynamics under conditions of thermal plasma spraying and claims that this effect is quite substantial with iron particles evaporating in an argon plasma flow as the calculation example. The same problem is re-examined in this communication by considering the intense evaporation of particles as a combined heat and mass transfer process and treating the 'rocket' force as a part of the total drag force acting on the evaporating particle. It is shown that the 'rocket' force caused by the non-uniform distribution of the evaporated-mass efflux from the evaporating particle makes up only a small percentage of the total drag force and thus is not important in determining the particle dynamics for the studied case. (comment)

  18. State of the art in medical applications using non-thermal atmospheric pressure plasma

    Science.gov (United States)

    Tanaka, Hiromasa; Ishikawa, Kenji; Mizuno, Masaaki; Toyokuni, Shinya; Kajiyama, Hiroaki; Kikkawa, Fumitaka; Metelmann, Hans-Robert; Hori, Masaru

    2017-12-01

    Plasma medical science is a novel interdisciplinary field that combines studies on plasma science and medical science, with the anticipation that understanding the scientific principles governing plasma medical science will lead to innovations in the field. Non-thermal atmospheric pressure plasma has been used for medical treatments, such as for cancer, blood coagulation, and wound healing. The interactions that occur between plasma and cells/tissues have been analyzed extensively. Direct and indirect treatment of cells with plasma has broadened the applications of non-thermal atmospheric pressure plasma in medicine. Examples of indirect treatment include plasma-assisted immune-therapy and plasma-activated medium. Controlling intracellular redox balance may be key in plasma cancer treatment. Animal studies are required to test the effectiveness and safety of these treatments for future clinical applications.

  19. Thermal Fatigue Behavior of Air-Plasma Sprayed Thermal Barrier Coating with Bond Coat Species in Cyclic Thermal Exposure

    Directory of Open Access Journals (Sweden)

    Ungyu Paik

    2013-08-01

    Full Text Available The effects of the bond coat species on the delamination or fracture behavior in thermal barrier coatings (TBCs was investigated using the yclic thermal fatigue and thermal-shock tests. The interface microstructures of each TBC showed a good condition without cracking or delamination after flame thermal fatigue (FTF for 1429 cycles. The TBC with the bond coat prepared by the air-plasma spray (APS method showed a good condition at the interface between the top and bond coats after cyclic furnace thermal fatigue (CFTF for 1429 cycles, whereas the TBCs with the bond coats prepared by the high-velocity oxygen fuel (HVOF and low-pressure plasma spray (LPPS methods showed a partial cracking (and/or delamination and a delamination after 780 cycles, respectively. The TBCs with the bond coats prepared by the APS, HVOF and LPPS methods were fully delaminated (>50% after 159, 36, and 46 cycles, respectively, during the thermal-shock tests. The TGO thickness in the TBCs was strongly dependent on the both exposure time and temperature difference tested. The hardness values were found to be increased only after the CFTF, and the TBC with the bond coat prepared by the APS showed the highest adhesive strength before and after the FTF.

  20. 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.

  1. Spray-dried chicken plasma improves intestinal digestive function and regulates intestinal selected microflora in weaning piglets.

    Science.gov (United States)

    Zhang, Y; Chen, D W; Yu, B; He, J; Yu, J; Mao, X B; Wang, J X; Luo, J Q; Huang, Z Q; Cheng, G X; Zheng, P

    2015-06-01

    One hundred forty-four 25-d-old weaning piglets with BW of 6.43 ± 0.39 kg were used in a 28-d trail to evaluate the effects of dietary addition of spray-dried chicken plasma (SDCP) as a replacement for spray-dried porcine plasma (SDPP) on growth performance, nutrient digestibility, diarrhea incidence, small intestinal morphology, digestive enzyme activity, and microflora. Pigs were randomly allotted to 1 of 4 dietary treatments: 1) CON (control; a basal diet), 2) SDPP (containing 5% SDPP), 3) SDPP + SDCP (containing 2.5% SDPP and 2.5% SDCP), and 4) SDCP (containing 5% SDCP). Six pigs from each treatment were randomly selected to collect serum and intestinal samples. Compared with the CON group, both the SDPP and the SDPP + SDCP groups improved final BW of pigs (P digestibility (ATTD) of CP, ether extract, Ca, and ash and less (P digestive enzymes activities, enhancing ATTD of nutrients, and decreasing diarrhea incidence.

  2. Micro-Biocidal Activity of Yeast Cells by Needle Plasma Irradiation at Atmospheric Pressure

    Science.gov (United States)

    Kurumi, Satoshi; Takahashi, Hideyuki; Taima, Tomohito; Suzuki, Kaoru; Hirose, Hideharu; Masutani, Shigeyuki

    In this study, we report on the biocidal activity technique by needle helium plasma irradiation at atmospheric pressure using borosilicate capillary nozzle to apply for the oral surgery. The diameter of needle plasma was less than 50 µm, and temperature of plasma irradiated area was less than body temperature. Needle plasma showed emission due to OH and O radical. Raman spectra and methylene blue stain showed yeast cells were inactivated by needle plasma irradiation.

  3. Fuel Evaporation in an Atmospheric Premixed Burner: Sensitivity Analysis and Spray Vaporization

    Directory of Open Access Journals (Sweden)

    Dávid Csemány

    2017-12-01

    Full Text Available Calculation of evaporation requires accurate thermophysical properties of the liquid. Such data are well-known for conventional fossil fuels. In contrast, e.g., thermal conductivity or dynamic viscosity of the fuel vapor are rarely available for modern liquid fuels. To overcome this problem, molecular models can be used. Currently, the measurement-based properties of n-heptane and diesel oil are compared with estimated values, using the state-of-the-art molecular models to derive the temperature-dependent material properties. Then their effect on droplet evaporation was evaluated. The critical parameters were liquid density, latent heat of vaporization, boiling temperature, and vapor thermal conductivity where the estimation affected the evaporation time notably. Besides a general sensitivity analysis, evaporation modeling in a practical burner ended up with similar results. By calculating droplet motion, the evaporation number, the evaporation-to-residence time ratio can be derived. An empirical cumulative distribution function is used for the spray of the analyzed burner to evaluate evaporation in the mixing tube. Evaporation number did not exceed 0.4, meaning a full evaporation prior to reaching the burner lip in all cases. As droplet inertia depends upon its size, the residence time has a minimum value due to the phenomenon of overshooting.

  4. Cold atmospheric plasma - A new technology for spacecraft component decontamination

    Science.gov (United States)

    Shimizu, Satoshi; Barczyk, Simon; Rettberg, Petra; Shimizu, Tetsuji; Klaempfl, Tobias; Zimmermann, Julia L.; Hoeschen, Till; Linsmeier, Christian; Weber, Peter; Morfill, Gregor E.; Thomas, Hubertus M.

    2014-01-01

    Cold atmospheric plasma (CAP) based on the Surface Micro-Discharge (SMD) technology was investigated for inactivation of different bacteria and endospores. The used technique was developed to serve as an alternative method for the decontamination of spacecraft components based on the COSPAR planetary protection policy where currently the dry heat microbial reduction method is the only applicable way to satisfy the required demands. However it is known, that dry heat can thermally damage sophisticated components installed on the device. Therefore, the development of a low temperature sterilization system is one of the high priority issues for upcoming space missions in the extraterrestrial field. In the study presented here, the vegetative bacteria Escherichia coli and Deinococcus radiodurans and several types of bacterial endospores - including Bacillus atrophaeus, Bacillus safensis, Bacillus megaterium, Bacillus megaterium 2c1 and Bacillus thuringiensis E24 - were inactivated by exposing them indirectly i.e. only to the reactive gases produced by the SMD electrode at room temperature. The results showed a 5 log inactivation for E. coli after 10 min of exposure. In contrast D. radiodurans proved to be more resistant resulting in a reduction of 3 log after exposure of 30 min. More than 6 log reductions were achieved for B. safensis, B. megaterium and B. megaterium 2c1 after 90 min of exposure. Furthermore the applicability of the used CAP system for spacecraft decontamination according to the planetary protection policy was investigated. This included also the investigation of the inactivation homogeneity by the plasma gas, the control of the temperature at the area of interest, the measurement of the O3 density in the treatment region and the detailed investigation of the effects of the exposure on different materials.

  5. Carbon nanotubes decorated with gold, platinum and rhodium clusters by injection of colloidal solutions into the post-discharge of an RF atmospheric plasma

    Energy Technology Data Exchange (ETDEWEB)

    Claessens, N; Demoisson, F; Dufour, T; Reniers, F [Service de Chimie Analytique et Chimie des Interfaces (CHANI), Universite Libre de Bruxelles, Faculte des Sciences, CP255, Boulevard du Triomphe 2, B-1050 Bruxelles (Belgium); Mansour, Ali; Guillot, J [Department ' Science and Analysis of Materials' (SAM), Centre de Recherche Public-Gabriel Lippmann, 41 rue du Brill, L-4422 Belvaux (Luxembourg); Felten, A; Pireaux, J-J [Facultes Universitaires Notre-Dame de la Paix, Centre de Recherche en Physique de la Matiere et du Rayonnement (PMR), 61 rue de Bruxelles, B-5000 Namur (Belgium)

    2010-09-24

    In this paper, we present a new, simple, robust and efficient technique to decorate multi-wall carbon nanotubes (MWCNT) with metal nanoparticles. As case studies, Au, Pt and Rh nanoparticles are grafted onto MWCNTs by spraying a colloidal solution into the post-discharge of an atmospheric argon or argon/oxygen RF plasma. The method that we introduce here is different from those usually described in the literature, since the treatment is operated at atmospheric pressure, allowing the realization in only one step of the surface activation and the deposition processes. We demonstrate experimentally that the addition of oxygen gas in the plasma increases significantly the amount of grafted metal nanoparticles. Moreover, TEM pictures clearly show that the grafted nanoparticles are well controlled in size.

  6. Electrochemical Behavior of CoNiCrAlY/ZrO2-Y2O3 Coated Layers with Atmospheric Pressure Plasma Technology in Seawater

    Science.gov (United States)

    Kim, Seong-Jong; Woo, Yong-Bin; Lee, Seung-Jun; Jeong, Jae-Yong

    2013-11-01

    Application of surface treatment has become common for protecting machine parts from oxidation, abrasion and corrosion induced by external environment. In particular, thermal spraying techniques are widely employed to improve wear, corrosion and thermal resistance. And compared to other methods they are simple and cost effective. However, the presence of porosity in the thermal spray coating can be highly detrimental because it provides access to penetration of corrosive matters, lowering corrosion resistance. Therefore, this research evaluate the electrochemical behavior under marine environment for aluminum-bronze alloy coated with MCrAlY and yttria-stabillized zirconia (YSZ) by atmospheric pressure plasma (APP) coating technology. Further application of carbon-based sealer removed voids and defects in the coating. The result reveled that, in case the voids and defects are completely removed, excellent corrosion resistance can be archived by application of good coating material along with formation of compact sealing layer.

  7. Chemical detoxification of trichloroethylene and 1,1,1-trichloroethane in a microwave discharge plasma reactor at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Krause, T.R.; Helt, J.E.

    1991-12-31

    This report focuses on the application of plasma technology to hazardous waste treatment. Microwave sustained plasmas are used to thermal degrade trichloroethylene and trichloroethane at atmospheric pressure. (JL)

  8. Kinetics of Tomato Peroxidase Inactivation by Atmospheric Pressure Cold Plasma Based on Dielectric Barrier Discharge

    OpenAIRE

    Cullen, Patrick; Pankaj, Shashi; Misra, N

    2013-01-01

    Atmospheric pressure cold plasma technology is an emerging nonthermal food technology for microbiological decontamination of food and bio-materials. This study demonstrates the applicability of in-package cold plasma technology as a novel means to inactivation of enzymes. The kinetics of inactivation of tomato peroxidase as a model enzyme was studied at 30, 40 and 50kV, for up to 5’ of atmospheric air dielectric barrier discharge plasma treatments. The enzyme activity was found to decrease wi...

  9. Atmospheric pressure plasma surface modification of titanium for high temperature adhesive bonding

    NARCIS (Netherlands)

    Akram, M.; Jansen, K.M.B.; Ernst, L.J.; Bhowmik, S.

    2011-01-01

    In this investigation surface treatment of titanium is carried out by plasma ion implantation under atmospheric pressure plasma in order to increase the adhesive bond strength. Prior to the plasma treatment, titanium surfaces were mechanically treated by sand blasting. It is observed that the

  10. Assessment of Atmospheric Pressure Plasma Treatment for Implant Osseointegration

    Directory of Open Access Journals (Sweden)

    Natalie R. Danna

    2015-01-01

    Full Text Available This study assessed the osseointegrative effects of atmospheric pressure plasma (APP surface treatment for implants in a canine model. Control surfaces were untreated textured titanium (Ti and calcium phosphate (CaP. Experimental surfaces were their 80-second air-based APP-treated counterparts. Physicochemical characterization was performed to assess topography, surface energy, and chemical composition. One implant from each control and experimental group (four in total was placed in one radius of each of the seven male beagles for three weeks, and one implant from each group was placed in the contralateral radius for six weeks. After sacrifice, bone-to-implant contact (BIC and bone area fraction occupancy (BAFO were assessed. X-ray photoelectron spectroscopy showed decreased surface levels of carbon and increased Ti and oxygen, and calcium and oxygen, posttreatment for Ti and CaP surfaces, respectively. There was a significant (P<0.001 increase in BIC for APP-treated textured Ti surfaces at six weeks but not at three weeks or for CaP surfaces. There were no significant (P=0.57 differences for BAFO between treated and untreated surfaces for either material at either time point. This suggests that air-based APP surface treatment may improve osseointegration of textured Ti surfaces but not CaP surfaces. Studies optimizing APP parameters and applications are warranted.

  11. Assessment of Atmospheric Pressure Plasma Treatment for Implant Osseointegration

    Science.gov (United States)

    Danna, Natalie R.; Beutel, Bryan G.; Tovar, Nick; Witek, Lukasz; Marin, Charles; Granato, Rodrigo; Suzuki, Marcelo; Coelho, Paulo G.

    2015-01-01

    This study assessed the osseointegrative effects of atmospheric pressure plasma (APP) surface treatment for implants in a canine model. Control surfaces were untreated textured titanium (Ti) and calcium phosphate (CaP). Experimental surfaces were their 80-second air-based APP-treated counterparts. Physicochemical characterization was performed to assess topography, surface energy, and chemical composition. One implant from each control and experimental group (four in total) was placed in one radius of each of the seven male beagles for three weeks, and one implant from each group was placed in the contralateral radius for six weeks. After sacrifice, bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) were assessed. X-ray photoelectron spectroscopy showed decreased surface levels of carbon and increased Ti and oxygen, and calcium and oxygen, posttreatment for Ti and CaP surfaces, respectively. There was a significant (P < 0.001) increase in BIC for APP-treated textured Ti surfaces at six weeks but not at three weeks or for CaP surfaces. There were no significant (P = 0.57) differences for BAFO between treated and untreated surfaces for either material at either time point. This suggests that air-based APP surface treatment may improve osseointegration of textured Ti surfaces but not CaP surfaces. Studies optimizing APP parameters and applications are warranted. PMID:26090443

  12. NiTi shape memory alloys coated with calcium phosphate by plasma-spraying. Chemical and biological properties

    Energy Technology Data Exchange (ETDEWEB)

    Prymak, O.; Epple, M. [Institute of Inorganic Chemistry, University of Duisburg-Essen, D-45117 Essen (Germany); Bogdansk, D.; Esenwein, S.A.; Koeller, M. [Department of Surgery, BG Kliniken Bergmannsheil - Universitaetsklinik, Buerkle-de-la-Camp-Platz 1, D-44780 Bochum (Germany)

    2004-05-01

    Plates of superelastic nickel-titanium shape memory alloy (NiTi) were coated with calcium phosphate (hydroxyapatite) by high-temperature plasma-spraying. The porous layer of about 100 {mu}m thickness showed a good adhesion to the metallic substrate that withstood bending of the plate but detached upon cutting the plate. The biocompatibility was tested by cultivation of blood cells (whole blood and isolated granulocytes [a subpopulation of blood leukocytes]). As substrates, pure NiTi, plasma-spray-coated NiTi and calcium phosphate-coated NiTi prepared by a dip-coating process were used. The adhesion of whole blood cells to all materials was not significantly different. In contrast, isolated granulocytes showed an increased adhesion to both calcium phosphate-coated NiTi samples. However, compared to non-coated NiTi or dip-coated NiTi, the number of dead granulocytes adherent to plasma-sprayed surfaces was significantly increased for isolated granulocytes (p<0.01). (Abstract Copyright [2004], Wiley Periodicals, Inc.) [German] Bleche aus superelastischer Nickel-Titan-Legierung (NiTi) wurden durch Hochtemperatur-Plasmaspritzen mit Calciumphosphat (Hydroxylapatit) beschichtet. Die Haftung der ca. 100 {mu}m starken poroesen Schicht auf der metallischen Unterlage ist so gut, dass das Blech gebogen werden kann. Das Schneiden des Bleches fuehrte allerdings zur Abloesung der Schicht. Die Biokompatibilitaet der beschichteten Bleche wurde im Zellkulturexperiment mit Blutzellen (Vollblut und isolierte Granulozyten, [eine Subpopulation von Blutleukozyten]) untersucht. Zum Vergleich wurden reines NiTi und Calciumphosphat-beschichtetes NiTi (hergestellt durch einen Tauchprozess) ebenfalls in der Zellkultur untersucht. Die Adhaerenz der Vollblutzellen an die Materialien war nicht signifikant unterschiedlich. Im Gegensatz dazu zeigten isolierte Granulozyten eine hoehere Adhaesion auf beiden Calciumphosphat-beschichteten NiTi-Proben. Die Anzahl von toten Granulozyten war auf

  13. Measurement and analysis for optical radiation of glow discharge plasma at atmospheric pressure

    Science.gov (United States)

    Ren, Qinglei; Lin, Qi

    2006-02-01

    The optical radiation measurement and analysis to the glow discharge plasma at atmospheric pressure have been done in the paper. The low temperature plasma due to atmospheric pressure glow discharge (APGD) in air has been produced on the planar surface of designed electrode plate. The optical radiation spectra of the plasma produced in two kinds of electrode plats with different power values loaded have been measured and sampled with the minitype grating spectrograph system. The acquired spectra data are processed averagely and analyzed. The results of analysis indicate that the optical characteristic of the APGD plasma is related to the loaded power and layout of the electrode plate. This shows that it is feasible to describe the characteristic parameters of APGD plasma qualitatively and control the strength of the APGD plasma quantitatively by the obtained relationship, which provides a convenient approach for utilizing APGD plasma effectively and also establishes some foundation to investigate APGD plasma further.

  14. Characterization and mechanical behaviour of reinforced hydroxyapatite coatings deposited by vacuum plasma spray on SS-316L alloy.

    Science.gov (United States)

    Singh, Amardeep; Singh, Gurbhinder; Chawla, Vikas

    2018-01-10

    Hydroxyapatite powder reinforced individually with 10wt percentage (wt%) of Al2O3 and ZrO2 (HA + 10wt% Al2O3 and HA + 10wt% ZrO2) was thermally sprayed onto SS-316L substrate with a bond coat of Zirconia by vacuum plasma spray (VPS) technique. The resulted coatings were heat treated at 700°C for 1h to study its effects on microstructural and mechanical properties of the deposited coatings. The characterization of the coatings was carried out using scanning electron microscope, x-ray diffraction, porosity, surface roughness and crystallinity using Rietveld analysis. The results indicated that after post coating heat treatment substantial decrease in porosity was witnessed along with significant improvement in crystallinity. Besides, the hardness across the cross-section of the coatings and bond strength was considerably improved; however the hardness of top coat was reduced owing to the loosening of un-melted and partially melted particles by diffusion process which takes place during heat treatment. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Hot Corrosion of Yttrium Stabilized Zirconia Coatings Deposited by Air Plasma Spray on a Nickel-Based Superalloy

    Science.gov (United States)

    Vallejo, N. Diaz; Sanchez, O.; Caicedo, J. C.; Aperador, W.; Zambrano, G.

    In this research, the electrochemical impedance spectroscopy (EIS) and Tafel analysis were utilized to study the hot corrosion performance at 700∘C of air plasma-sprayed (APS) yttria-stabilized zirconia (YSZ) coatings with a NiCrAlY bond coat grown by high velocity oxygen fuel spraying (HVOF), deposited on an INCONEL 625 substrate, in contact with corrosive solids salts as vanadium pentoxide V2O5 and sodium sulfate Na2SO4. The EIS data were interpreted based on proposed equivalent electrical circuits using a suitable fitting procedure performed with Echem AnalystTM Software. Phase transformations and microstructural development were examined using X-ray diffraction (XRD), with Rietveld refinement for quantitative phase analysis, scanning electron microscopy (SEM) was used to determinate the coating morphology and corrosion products. The XRD analysis indicated that the reaction between sodium vanadate (NaVO3) and yttrium oxide (Y2O3) produces yttrium vanadate (YVO4) and leads to the transformation from tetragonal to monoclinic zirconia phase.

  16. Vacuum plasma sprayed coatings using ionic silver doped hydroxyapatite powder to prevent bacterial infection of bone implants.

    Science.gov (United States)

    Guimond-Lischer, Stefanie; Ren, Qun; Braissant, Olivier; Gruner, Philipp; Wampfler, Bruno; Maniura-Weber, Katharina

    2016-03-10

    Fast and efficient osseointegration of implants into bone is of crucial importance for their clinical success; a process that can be enhanced by coating the implant surface with hydroxyapatite (HA) using the vacuum plasma spray technology (VPS). However, bacterial infections, especially the biofilm formation on implant surfaces after a surgery, represent a serious complication. With ever-increasing numbers of antibiotic-resistant bacteria, there is great interest in silver (Ag) as an alternative to classical antibiotics due to its broad activity against Gram-positive and Gram-negative bacterial strains. In the present study, silver ions were introduced into HA spray powder by ion exchange and the HA-Ag powder was applied onto titanium samples by VPS. The Ag-containing surfaces were evaluated for the kinetics of the silver release, its antibacterial effect against Staphylococcus aureus as well as Escherichia coli, and possible cytotoxicity against human bone cells. The HA-Ag coatings with different concentrations of Ag displayed mechanical and compositional properties that fulfill the regulatory requirements. Evaluation of the Ag release kinetic showed a high release rate in the first 24 h followed by a decreasing release rate over the four subsequent days. The HA-Ag coatings showed no cytotoxicity to primary human bone cells while exhibiting antibacterial activity to E. coli and S. aureus.

  17. Microstructural Effects and Properties of Non-line-of-Sight Coating Processing via Plasma Spray-Physical Vapor Deposition

    Science.gov (United States)

    Harder, Bryan J.; Zhu, Dongming; Schmitt, Michael P.; Wolfe, Douglas E.

    2017-08-01

    Plasma spray-physical vapor deposition (PS-PVD) is a unique processing method that bridges the gap between conventional thermal spray and vapor phase methods, and enables highly tailorable coatings composed of a variety of materials in thin, dense layers or columnar microstructures with modification of the processing conditions. The strengths of this processing technique are material and microstructural flexibility, deposition speed, and potential for non-line-of-sight (NLOS) capability by vaporization of the feedstock material. The NLOS capability of PS-PVD is investigated here using yttria-stabilized zirconia and gadolinium zirconate, which are materials of interest for turbine engine applications. PS-PVD coatings were applied to static cylindrical substrates approximately 6-19 mm in diameter to study the coating morphology as a function of angle. In addition, coatings were deposited on flat substrates under various impingement configurations. Impingement angle had significant effects on the deposition mode, and microscopy of coatings indicated that there was a shift in the deposition mode at approximately 90° from incidence on the cylindrical samples, which may indicate the onset of more turbulent flow and PVD-like growth. Coatings deposited at non-perpendicular angles exhibited a higher density and nearly a 2× improvement in erosion performance when compared to coatings deposited with the torch normal to the surface.

  18. Topographic, optical and chemical properties of zinc particle coatings deposited by means of atmospheric pressure plasma

    Energy Technology Data Exchange (ETDEWEB)

    Wallenhorst, L.M., E-mail: lena.wallenhorst@hawk-hhg.de [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Loewenthal, L.; Avramidis, G. [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Gerhard, C. [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Fraunhofer Institute for Surface Engineering and Thin Films, Application Center for Plasma and Photonics, Von-Ossietzky-Str. 100, 37085 Göttingen (Germany); Militz, H. [Wood Biology and Wood Products, Burckhardt Institute, Georg-August-University Göttingen, Büsgenweg 4, 37077 Göttingen (Germany); Ohms, G. [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Viöl, W. [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Fraunhofer Institute for Surface Engineering and Thin Films, Application Center for Plasma and Photonics, Von-Ossietzky-Str. 100, 37085 Göttingen (Germany)

    2017-07-15

    Highlights: • Zn/ZnO mixed systems were deposited from elemental zinc by a cold plasma-spray process. • Oxidation was confirmed by XPS. • The coatings exhibited a strong absorption in the UV spectral range, thus being suitable as protective layers, e.g. on thermosensitive materials. - Abstract: In this research, topographic, optical and chemical properties of zinc oxide layers deposited by a cold plasma-spray process were measured. Here, zinc micro particles were fed to the afterglow of a plasma spark discharge whereas the substrates were placed in a quite cold zone of the effluent plasma jet. In this vein, almost closed layers were realised on different samples. As ascertained by laser scanning and atomic force microscopic measurements the particle size of the basic layer is in the nanometre scale. Additionally, larger particles and agglomerates were found on its top. The results indicate a partial plasma-induced diminishment of the initial particles, most probably due to melting or vaporisation. It is further shown that the plasma gives rise to an increased oxidation of such particles as confirmed by X-ray photoelectron spectroscopy. Quantitative analysis of the resulting mixed layer was performed. It is shown that the deposited layers consist of zinc oxide and elemental zinc in approximately equal shares. In addition, the layer's band gap energy was determined by spectroscopic analysis. Here, considerable UV blocking properties of the deposited layers were observed. Possible underlying effects as well as potential applications are presented.

  19. Surface modification of polylactic acid films by atmospheric pressure plasma treatment

    Science.gov (United States)

    Kudryavtseva, V. L.; Zhuravlev, M. V.; Tverdokhlebov, S. I.

    2017-09-01

    A new approach for the modification of polylactic acid (PLA) materials using atmospheric pressure plasma (APP) is described. PLA films plasma exposure time was 20, 60, 120 s. The surface morphology and wettability of the obtained PLA films were investigated by atomic force microscopy (AFM) and the sitting drop method. The atmospheric pressure plasma increased the roughness and surface energy of PLA film. The wettability of PLA has been improved with the application of an atmospheric plasma surface treatment. It was shown that it is possible to obtain PLA films with various surface relief and tunable wettability. Additionally, we demonstrated that the use of cold atmospheric pressure plasma for surface activation allows for the immobilization of bioactive compounds like hyaluronic acid (HA) on the surface of obtained films. It was shown that composite PLA-HA films have an increased long-term hydrophilicity of the films surface.

  20. Prediction Performance of Blackout and Plasma Attenuation in Atmospheric Reentry Demonstrator Mission

    OpenAIRE

    Takahashi, Yusuke; Yamada, Kazuhiko; Abe, Takashi

    2014-01-01

    A numerical simulation model that combines the plasma ows and electromagnetic waves around a reentry vehicle during atmospheric reentry was developed to evaluate the radio frequency blackout and plasma attenuation. The physical properties of the plasma ow in the shock layer and wake region were obtained using a computational uid dynamics technique. The electromagnetic waves were expressed using a frequency- dependent nite-difference time-domain method with the plasma ...

  1. Deactivation of Enterococcus Faecalis Bacteria by an Atmospheric Cold Plasma Brush

    Science.gov (United States)

    Chen, Wei; Huang, Jun; Du, Ning; Liu, Xiao-Di; Lv, Guo-Hua; Wang, Xing-Quan; Zhang, Guo-Ping; Guo, Li-Hong; Yang, Si-Ze

    2012-07-01

    An atmospheric cold plasma brush suitable for large area and low-temperature plasma-based sterilization is designed and used to treat enterococcus faecalis bacteria. The results show that the efficiency of the inactivation process by helium plasma is dependent on applied power and exposure time. After plasma treatments, the cell structure and morphology changes can be observed by scanning electron microscopy. Optical emission measurements indicate that reactive species such as O and OH play a significant role in the sterilization process.

  2. Microstructures and tribological properties of plasma sprayed WC-Co-Cu-BaF 2/CaF 2 self-lubricating wear resistant coatings

    Science.gov (United States)

    Yuan, Jianhui; Zhu, Yingchun; Ji, Heng; Zheng, Xuebing; Ruan, Qichao; Niu, Yaran; Liu, Ziwei; Zeng, Yi

    2010-06-01

    A promising WC-Co-Cu-BaF 2/CaF 2 self-lubricating wear resistant coating was deposited via atmospheric plasma spraying (APS) process by using homemade feedstock powders composed of WC-Co, Cu and BaF 2/CaF 2 eutectic. The as-prepared cermet coatings had better frictional behavior comparing with the WC-Co coating. Moreover, the often-occurred decarburization of WC in APS process was noticeably improved due to the binding of copper and BaF 2/CaF 2 phase, which not only offered effective solid lubrication, but also acted as bind phases to mend the microstructure and protected WC from decomposition. The optimized specimen contained 10 wt.% Cu and 10 wt.% BaF 2/CaF 2 in a WC-Co matrix, which had excellent frictional and wear performance. The wear mechanism of the self-lubricating wear resistant coating was discussed with the microstructures, compositions and mechanical properties of the composite materials in detail.

  3. Dose-Dependent Effects of CeO2 on Microstructure and Antibacterial Property of Plasma-Sprayed TiO2 Coatings for Orthopedic Application

    Science.gov (United States)

    Zhao, Xiaobing; Liu, Gaopeng; Zheng, Hai; Cao, Huiliang; Liu, Xuanyong

    2015-02-01

    Titanium and its alloys have been used extensively for orthopedic and dental implants. Although these devices have achieved high rates of success, two major complications may be encountered: the lack of osseointegration and the biomaterial-related infection. Accordingly, cerium oxide (CeO2)-doped titanium oxide (TiO2) materials were coated on titanium by an atmospheric plasma spraying (APS) technique. The phase structures, morphologies, and surface chemical states of the obtained coatings were characterized by x-ray diffraction, scanning electron microscopy, and x-ray photoelectron spectroscopy techniques. The in vitro antibacterial and cytocompatibility of the materials were studied with Staphylococcus aureus ( S. aureus, ATCC25923) and osteoblast precursor cell line MC3T3-E1. The results indicated that the addition of CeO2 shifts slightly the diffraction peaks of TiO2 matrix to low angles but does not change its rutile phase structure. In addition, the CeO2/TiO2 composite coatings possess dose-dependent corrosion resistance and antimicrobial properties. And doping of 10 wt.% CeO2 exhibits the highest activity against S. aureus, improved corrosion resistance, and competitive cytocompatibility, which argues a promising option for balancing the osteogenetic and antibacterial properties of titanium implants.

  4. Numerical study of the spreading and solidification of a molten particle impacting onto a rigid substrate under plasma spraying conditions

    Directory of Open Access Journals (Sweden)

    Oukach Soufiane

    2015-01-01

    Full Text Available This paper deals with simulation of the spreading and solidification of a fully molten particle impacting onto a preheated substrate under traditional plasma spraying conditions. The multiphase problem governing equations of mass, momentum and energy conservation taking into account heat transfer by conduction, convection and phase change are solved by using a Finite Element approach. The interface between molten particle and surrounding air, is tracked using the Level Set method. The effect of the Reynolds number on the droplet spreading and solidification, using a wide range of impact velocities (40-250m/s, is reported. A new correlation that predicts the final spread factor of splat as a function of Reynolds number is obtained. Thermal contact resistance, viscous dissipation, wettability and surface tension forces effects are taken into account.

  5. Induction of osteoconductivity by BMP-2 gene modification of mesenchymal stem cells combined with plasma-sprayed hydroxyapatite coating

    Science.gov (United States)

    Wu, Jiang; Guo, Ying-qiang; Yin, Guang-fu; Chen, Huai-qing; Kang, Yunqing

    2008-11-01

    Success in bone implant depends greatly on the composition and surface features of the implant. The surface-modification measures not only favor the implant's osteoconductivity, but also promote both bone anchoring and biomechanical stability. This paper reports an approach to combine a hydroxyapatite (HA) coated substrate with a cellular vehicle for the delivery of bone morphogenetic protein-2 (BMP-2) synergistically enhancing the osteoconductivity of implant surfaces. We examined the attachment, growth and osteoinductive activity of transfected BMP-producing bone marrow mesenchymal stem cells (BMSCs) on a plasma-sprayed HA coated substrate. It was found that the HA coated substrate could allow the attachment and growth of BMP-2 gene modified BMSCs, and this combined application synergistically enhanced osteconductivity of the substrate surface. This synergistic method may be of osseointegration value in orthopedic and dental implant surgery.

  6. Nondestructive inspection of thin plasma-sprayed ceramic and cermet protective coatings for coal conversion and utilization equipment

    Energy Technology Data Exchange (ETDEWEB)

    Scott, G.W.; Cook, K.V.; Davis, E.V.; Dodd, C.V.; Foster, B.E.; Mason, W.J.; McClung, R.W.; Simpson, W.A. Jr.; Snyder, S.D.

    1978-04-01

    Results of a project to develop nondestructive inspection techniques for ceramic and cermet wear- and process-resistant coatings used in coal system compounds are described. The general inspection problem has been analyzed and the difficulties peculiar to plasma-sprayed coatings are discussed. Physical properties, especially porosity, and the nominal 0.25 mm thickness make the inspection of these coatings difficult. The literature has been reviewed for inspection methods and technology adaptable to coating inspection. Several inspection methods have been evaluated for feasibility by laboratory experiments. The basic coating defect conditions considered are cracks or holes, variations in thickness, lamellar separations, and inhomogeneities. Assessment of current technology indicates that a few nondestructive methods can be applied directly to the inspection of coatings with very little development; in most cases, however, considerable development is required.

  7. Retention Improvement in Fluoride Application with Cold Atmospheric Plasma.

    Science.gov (United States)

    Kim, Y M; Lee, H Y; Lee, H J; Kim, J B; Kim, S; Joo, J Y; Kim, G C

    2017-09-01

    This study aimed to apply fluoride formulations to enamel with cold atmospheric plasma (CAP) and analyze the fluoride uptake, retention, and acid resistance quantitatively. Human enamel specimens were divided randomly into 2 groups: group APF1, 1.23% acidulated phosphate fluoride (APF) gel; group APF2, 1.23% APF gel with CAP. Fluoride and CAP were applied to the samples 4 times at 1-wk intervals. The specimens were also stored in artificial saliva for 4 wk to evaluate the retention of fluoride. The fluoride content on the fluoride-treated enamel was measured by an electron probe microanalyzer. To detect the resistance to demineralization, the calcium-to-phosphate ratio of the enamel samples was measured after the application of APF gel with or without CAP, followed by soaking in the demineralization solution. In groups APF1 and APF2, the amount of fluoride detected increased depending on the application frequency, and more fluoride was detected in group APF2 than in group APF1. In the experiment examining the maintenance effect, fluoride was not detected in group APF1, whereas fluoride was detected in group APF2 up to the fourth week. As for the resistance to demineralization, the calcium-to-phosphate ratio of the enamel treated with APF and CAP was higher than that treated with APF alone, and it increased with the frequency of treatment. This study suggests that the combination treatment of CAP and fluoride improves retention of fluoride on the enamel and resistance to demineralization when compared with treatment with fluoride alone.

  8. Spectroscopic characterization of atmospheric pressure um-jet plasma source

    CERN Document Server

    Bibinov, Nikita; Bahre, Hendrik; Awakowicz, Peter; der Gathen, Volker Schulz-von

    2011-01-01

    A radio frequency um-jet plasma source is studied using He/O2 mixture. This um-jet can be used for different applications as a source of chemical active species e.g. oxygen atoms, molecular metastables and ozone. Using absolutely-calibrated optical emission spectroscopy and numerical simulation, the gas temperature in active plasma region and plasma parameters (electron density and electron distribution function) are determined. Concentrations of oxygen atoms and ozone in the plasma channel and in the effluent of the plasma source are measured using emission and absorption spectroscopy. To interpret the measured spatial distributions, the steady-state species' concentrations are calculated using determined plasma parameters and gas temperature. At that the influence of the surface processes and gas flow regime on the loss of the active species in the plasma source are discussed. The measured spatial distributions of oxygen atom and ozone densities are compared with the simulated ones.

  9. C{sub 18}-attached membrane funnel-based spray ionization mass spectrometry for quantification of anti-diabetic drug from human plasma

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wan [Department of Chemistry, The Chinese University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong); Chen, Xiangfeng, E-mail: xiangfchensdas@163.com [Department of Chemistry, The Chinese University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong); Shandong Analysis and Test Centre, Shandong Academy of Sciences, Jinan, Shandong (China); Wong, Y.-L. Elaine; Hung, Y.-L. Winnie; Wang, Ze; Deng, Liulin [Department of Chemistry, The Chinese University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong); Dominic Chan, T.-W., E-mail: twdchan@cuhk.edu.hk [Department of Chemistry, The Chinese University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong)

    2016-08-24

    In this work, sorbent-attached membrane funnel-based spray ionization mass spectrometry was explored for quantitative analysis of anti-diabetic drugs spiked in human plasma. C{sub 18}-attached membrane funnel was fabricated for in situ extraction and clean-up to alleviate matrix suppression effect in the ionization process. Repaglinide was used as a target analyte of anti-diabetic drugs. Under optimal working conditions, good linearity (R{sup 2} > 0.99) was obtained in the concentration range of 1–100 ng mL{sup −1}. The method detection limit of target drugs spiked in the human plasma was around 0.30 ng mL{sup −1}. Through the application of an isotope-labeled internal standard, the signal fluctuation caused by residual background matrices was largely alleviated and the precision of measurement (RSD) was below 15%. The recovery of repaglinide for 5, 25, and 100 ng mL{sup −1} of spiked human plasma matrixes ranged from 87% to 112%. The developed method was successfully applied to determine repaglinide in plasma volunteers who orally received a dose of drug association. Our results demonstrated that membrane funnel-based spray is a simple and sensitive method for rapid screening analysis of complex biological samples. - Highlights: • Sorbent attached membrane funnel based spray platform was used for drug determination in human plasma. • The matrix suppression effect of human plasma was largely eliminated. • The method was applied to determine repaglinide in plasma volunteers. • Membrane funnel-based spray is promising for analysis of biological samples.

  10. Properties of the acrylic acid polymers obtained by atmospheric pressure plasma polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Topala, Ionut [Plasma Physics Laboratory, Faculty of Physics, Al. I. Cuza University, 11 Carol I Boulevard, 700506 Iasi (Romania)], E-mail: itopala@plasma.uaic.ro; Dumitrascu, Nicoleta; Popa, Gheorghe [Plasma Physics Laboratory, Faculty of Physics, Al. I. Cuza University, 11 Carol I Boulevard, 700506 Iasi (Romania)

    2009-01-15

    Plasma polymers of acrylic acid were obtained using an atmospheric pressure discharge system. The plasma polymerization reactor uses a dielectric barrier discharge, with the polyethylene terephthalate dielectric acting as substrate for deposition. The plasma was characterized by specific electrical measurements, monitoring the applied voltage and the discharge current. Based on the spatially resolved optical emission spectroscopy, we analyzed the distribution of the excited species in the discharge gap, specific plasma temperatures (vibrational and gas temperatures) being calculated with the Boltzmann plot method. The properties of the plasma polymer films were investigated by contact angle measurements, infrared and UV-Vis spectroscopy, scanning electron microscopy. The films produced by plasma polymerization at atmospheric pressure showed a hydrophilic character, in correlation with the strong absorbance of OH groups in the FTIR spectrum. Moreover, the surface of the plasma polymers at micrometric scale is smooth and free of defects without particular features.

  11. Treatment of enterococcus faecalis bacteria by a helium atmospheric cold plasma brush with oxygen addition

    Energy Technology Data Exchange (ETDEWEB)

    Chen Wei; Huang Jun; Wang Xingquan; Lv Guohua; Zhang Guoping [Key Laboratory of Soft Matter Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, 100190 Beijing (China); Du Ning; Liu Xiaodi; Guo Lihong [Department of Oral Biology, Peking University School and Hospital of Stomatology, 100080 Beijing (China); Yang Size [Key Laboratory of Soft Matter Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, 100190 Beijing (China); Fujian Key Laboratory for Plasma and Magnetic Resonance, Department of Aeronautics, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen 361005 (China)

    2012-07-01

    An atmospheric cold plasma brush suitable for large area and low-temperature plasma-based sterilization is designed. Results demonstrate that the He/O{sub 2} plasma more effectively kills Enterococcus faecalis than the pure He plasma. In addition, the sterilization efficiency values of the He/O{sub 2} plasma depend on the oxygen fraction in Helium gas. The atmospheric cold plasma brush using a proper ratio of He/O{sub 2} (2.5%) reaches the optimum sterilization efficiency. After plasma treatment, the cell structure and morphology changes can be observed by the scanning electron microscopy. Optical emission measurements indicate that reactive species such as O and OH play a significant role in the sterilization process.

  12. Treatment of enterococcus faecalis bacteria by a helium atmospheric cold plasma brush with oxygen addition

    Science.gov (United States)

    Chen, Wei; Huang, Jun; Du, Ning; Liu, Xiao-Di; Wang, Xing-Quan; Lv, Guo-Hua; Zhang, Guo-Ping; Guo, Li-Hong; Yang, Si-Ze

    2012-07-01

    An atmospheric cold plasma brush suitable for large area and low-temperature plasma-based sterilization is designed. Results demonstrate that the He/O2 plasma more effectively kills Enterococcus faecalis than the pure He plasma. In addition, the sterilization efficiency values of the He/O2 plasma depend on the oxygen fraction in Helium gas. The atmospheric cold plasma brush using a proper ratio of He/O2 (2.5%) reaches the optimum sterilization efficiency. After plasma treatment, the cell structure and morphology changes can be observed by the scanning electron microscopy. Optical emission measurements indicate that reactive species such as O and OH play a significant role in the sterilization process.

  13. Comparison of free radicals formation induced by cold atmospheric plasma, ultrasound, and ionizing radiation.

    Science.gov (United States)

    Rehman, Mati Ur; Jawaid, Paras; Uchiyama, Hidefumi; Kondo, Takashi

    2016-09-01

    Plasma medicine is increasingly recognized interdisciplinary field combining engineering, physics, biochemistry and life sciences. Plasma is classified into two categories based on the temperature applied, namely "thermal" and "non-thermal" (i.e., cold atmospheric plasma). Non-thermal or cold atmospheric plasma (CAP) is produced by applying high voltage electric field at low pressures and power. The chemical effects of cold atmospheric plasma in aqueous solution are attributed to high voltage discharge and gas flow, which is transported rapidly on the liquid surface. The argon-cold atmospheric plasma (Ar-CAP) induces efficient reactive oxygen species (ROS) in aqueous solutions without thermal decomposition. Their formation has been confirmed by electron paramagnetic resonance (EPR) spin trapping, which is reviewed here. The similarities and differences between the plasma chemistry, sonochemistry, and radiation chemistry are explained. Further, the evidence for free radical formation in the liquid phase and their role in the biological effects induced by cold atmospheric plasma, ultrasound and ionizing radiation are discussed. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Intracellular effects of atmospheric-pressure plasmas on melanoma cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Ishaq, M., E-mail: ishaqmusarat@gmail.com [Peter MacCallum Cancer Centre, East Melbourne, VIC 3002 (Australia); Comonwealth Scientific and Industrial Research Organization, Sydney, New South Wales (Australia); Bazaka, K. [Institute for Health and Biomedical Innovation, School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD 4000 (Australia); Ostrikov, K. [Comonwealth Scientific and Industrial Research Organization, Sydney, New South Wales (Australia); Institute for Health and Biomedical Innovation, School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD 4000 (Australia)

    2015-12-15

    Gas discharge plasmas formed at atmospheric pressure and near room temperature have recently been shown as a promising tool for cancer treatment. The mechanism of the plasma action is attributed to generation of reactive oxygen and nitrogen species, electric fields, charges, and photons. The relative importance of different modes of action of atmospheric-pressure plasmas depends on the process parameters and specific treatment objects. Hence, an in-depth understanding of biological mechanisms that underpin plasma-induced death in cancer cells is required to optimise plasma processing conditions. Here, the intracellular factors involved in the observed anti-cancer activity in melanoma Mel007 cells are studied, focusing on the effect of the plasma treatment dose on the expression of tumour suppressor protein TP73. Over-expression of TP73 causes cell growth arrest and/or apoptosis, and hence can potentially be targeted to enhance killing efficacy and selectivity of the plasma treatment. It is shown that the plasma treatment induces dose-dependent up-regulation of TP73 gene expression, resulting in significantly elevated levels of TP73 RNA and protein in plasma-treated melanoma cells. Silencing of TP73 expression by means of RNA interference inhibited the anticancer effects of the plasma, similar to the effect of caspase inhibitor z-VAD or ROS scavenger N-acetyl cysteine. These results confirm the role of TP73 protein in dose-dependent regulation of anticancer activity of atmospheric-pressure plasmas.

  15. Trajectory effect on the properties of large area ZnO thin films deposited by atmospheric pressure plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Juang, Jia-Yang, E-mail: jiayang@ntu.edu.tw [Department of Mechanical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Chou, Tung-Sheng; Lin, Hsin-Tien; Chou, Yuan-Fang [Department of Mechanical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Weng, Chih-Chiang [Mechanical and Systems Research Laboratories, Industrial Technology Research Institute, Hsinchu 31040, Taiwan (China)

    2014-09-30

    Highlights: • We develop a cost-effective technique, atmosphere pressure plasma jet (APPJ), to deposit gallium-doped zinc oxide (GZO) films on large area glass substrates in atmosphere. • Scanning trajectory has a significant impact on the pattern of sheet resistance distribution. • The primary root cause of the nonuniformity is the annealing effect of the deposited films in air while the nozzle scans over the rest of the substrate. • Equivalent circuits models considering only the resistance increase due to air annealing cannot explain the unexpected rise of resistance in the center of the substrate for multiple-pass samples. • Measurements of residual stress, carrier concentration and Hall mobility reveal that the residual stress is another factor that results in nonuniform resistance distribution. - Abstract: Large area (117 mm × 185 mm) gallium-doped zinc oxide (GZO) films are prepared on glass substrates by atmospheric pressure plasma jet (APPJ) technique. The uniformity of material properties, in particular the electrical resistivity, of the deposited film is of great importance in reducing design complexity of the electron devices. We investigate the effects of scanning trajectory recipe (speed, pitch and number of passes) on structural and electrical properties of GZO thin films. We find that the trajectory has significant effects on the magnitude and uniformity of sheet resistance over the glass substrates. For single pass, the resistance appears higher at the starting part of spray, whereas, for cases of multiple passes, the highest resistance appears in the central part of the substrate. XRD, SEM, Hall measurement and residual stress are used to study the film properties and identify root causes of the nonuniform distribution of sheet resistance. We conclude that annealing time is the dominant root cause of the nonuniform resistance distribution, and other factors such as residual stress and structural characteristics may also have

  16. Cold Atmospheric Plasma Induces a Predominantly Necrotic Cell Death via the Microenvironment: e0133120

    National Research Council Canada - National Science Library

    François Virard; Sarah Cousty; Jean-Pierre Cambus; Alexis Valentin; Philippe Kémoun; Franck Clément

    2015-01-01

      Introduction Cold plasma is a partially ionized gas generated by an electric field at atmospheric pressure that was initially used in medicine for decontamination and sterilization of inert surfaces...

  17. Sterilization effect of atmospheric pressure non-thermal air plasma on dental instruments

    National Research Council Canada - National Science Library

    Sung, Su-Jin; Huh, Jung-Bo; Yun, Mi-Jung; Chang, Brian Myung W; Jeong, Chang-Mo; Jeon, Young-Chan

    2013-01-01

    .... To develop a dental sterilizer which can sterilize most materials, such as metals, rubbers, and plastics, the sterilization effect of an atmospheric pressure non-thermal air plasma device was evaluated...

  18. The study of the effects of sea-spray drops on the marine atmospheric boundary layer by direct numerical simulation

    Science.gov (United States)

    Druzhinin, Oleg A.; Troitskaya, Yuliya I.; Zilitinkevich, Sergej S.

    2017-04-01

    Detailed knowledge of the interaction of wind with surface water waves is necessary for correct parameterization of turbulent exchange at the air-sea interface in prognostic models. At sufficiently strong winds, sea-spray-generated droplets interfere with the wind-waves interaction. The results of field experiments and laboratory measurements (Andreas et al., JGR 2010) show that mass fraction of air-borne spume water droplets increases with the wind speed and their impact on the carrier air-flow may become significant. Phenomenological models of droplet-laden marine atmospheric boundary layer (Kudryavtsev & Makin, Bound.-Layer Met. 2011) predict that droplets significantly increase the wind velocity and suppress the turbulent air stress. The results of direct numerical simulation (DNS) of a turbulent particle-laden Couette flow over a flat surface show that inertial particles may significantly reduce the carrier flow vertical momentum flux (Richter & Sullivan, GRL 2013). The results also show that in the range of droplet sizes typically found near the air-sea interface, particle inertial effects are significant and dominate any particle-induced stratification effects. However, so far there has been no attempt to perform DNS of a droplet-laden air-flow over waved water surface. The objective of the present paper is to elucidate possible effects of sea spray on the momentum transfer in marine boundary layer under strong wind-forcing conditions by performing direct numerical simulation (DNS) of turbulent, droplet-laden air-flow over a waved water surface. Three-dimensional, turbulent Couette air-flow is considered in DNS as a model of a constant-flux layer in the atmospheric surface layer. Two-dimensional stationary waves at the water surface are prescribed and assumed to be unaffected by the air-flow and/or droplets. Droplets are considered as non-deformable spheres and tracked in a Lagrangian framework, and their impact on the carrier flow is modeled with the use of

  19. Generation of microwave-excited atmospheric-pressure line plasma and its application

    Science.gov (United States)

    Kuwahata, Hiroshi; Miyata, Hiroshi; Isomura, Masao; Shindo, Haruo

    2017-12-01

    A new 2.45 GHz microwave-excited atmospheric-pressure line plasma system was developed. An atmospheric-pressure helium (He) line plasma with a length of ∼350 mm and a width of ∼6 mm was generated in air at a microwave power of 1100 W. The length of the He line plasma was varied in the range of ∼120–350 mm by changing the width of the waveguide in the microwave tube and the position of the short plunger. When a Si wafer was irradiated with the He line plasma for 10 s, the surface of the Si wafer became superhydrophilic in a belt shape. On the basis of these results, the new microwave-excited atmospheric-pressure He line plasma system was found to be effective for dry cleaning large-area surfaces, such as semiconductor substrates and glass plates used in flat-panel displays.

  20. Development of hydroxyapatite crystallization utilizing the contact reaction of a minute droplet with atmospheric plasmas

    Science.gov (United States)

    Wada, Y.; Kudoh, K.; Matsumoto, M.; Onoe, K.

    2017-05-01

    For the creation of a new crystallization method of hydroxyapatite ((Ca10(PO4)6(OH)2); HAp) fine particles through a simplified operation, a combined system of atmospheric plasma with minute droplets was developed. An atmospheric pressure plasma-jet was generated by an inductively coupled plasma method that is contacted to minute droplets including HAp liquid sources as Ca, PO4 and OH elements. In this paper, the effects of the organic compound chemical properties and plasma irradiation power on production of HAp fine particles were examined. Consequently, the fine spherical particles of HAp are generated by the introduction of minute droplets including Ca, PO4 and OH elements into an atmospheric plasma field. Moreover, when citric acid is added to a HAp liquid source for minute droplets, HAp yield is increased 2-times compared to other operations. In conclusion, crystalline HAp is obtained without calcination under conditions of RF irradiation power at 1500 W.

  1. Surface modification of polylactic acid (PLA) by air atmospheric plasma treatment

    OpenAIRE

    Jordá Vilaplana, Amparo; Fombuena Borrás, Vicent; García García, Daniel; Samper Madrigal, María Dolores; Sánchez Nacher, Lourdes

    2014-01-01

    The main objective of this experimental study is the validation of the technique of atmospheric plasma with the aim of improving the surface energy of the polylactic acid (PLA) for further adhesion uses. The wettability of PLA has been improved with the application of an atmospheric plasma surface treatment. This method provides good adhesion properties with the optimizing the process parameters in terms of the nozzle substrate distance and sample advance rate. In order to achieve that goal, ...

  2. Uso de plasma suíno desidratado por Spray-Dryer na dieta de leitões desmamados precocemente The use of Spray-Dried porcine plasma in early-weaned pig diets

    Directory of Open Access Journals (Sweden)

    Eduardo Afonso F. Butolo

    1999-04-01

    Full Text Available O objetivo deste trabalho foi avaliar o uso do plasma suíno desidratado (PSD, na dieta de leitões desmamados aos 21 dias de idade. Cento e vinte leitões, com peso médio inicial de 5,75 kg, foram usados para testar os níveis de inclusão de 0; 2,5; 5,0; e 7,5% de plasma na fase 1 (0 a 14 dias e o seu efeito na fase 2 (14 a 28 dias. À exceção dos leitões mantidos em dieta controle, o restante foi alimentado com ração inicial com 2,5% PSD e 2,5% de hemácias desidratadas no período 15 a 28 dias pós-desmama. As dietas foram formuladas para conter nas fases 1 e 2, respectivamente, 1,40 e 1,20% de lisina, 0,54 e 0,41% de metionina e 15 e 8% de lactose. Foi usado delineamento experimental em blocos casualizados, com cinco repetições por tratamento e seis animais por unidade experimental. O consumo médio diário de ração aumentou linearmente, nas fases 1 e 2, com o aumento de PSD na ração. No período de 0 a 28 dias, houve resposta linear para o consumo médio diário de ração para os níveis de PSD da fase 1. O plasma estimulou maior consumo de ração pré-inicial, nas duas semanas subseqüentes ao desmame. Este efeito foi mantido durante a segunda fase (15 a 28 dias pós-desmame, quando foi usada na ração inicial combinação de 2,5% de plasma e 2,5% de hemácias desidratada.The objective of this work was to evaluate the spray-dried porcine plasma (SDPP in the diet of 21 day-weaned pig. One hundred and twenty piglets averaging 5.75 kg of initial weight were used to test the inclusion levels of 0, 2.5, 5.0, and 7.5% of porcine plasma on phase 1 (from 0 to 14 days and its effects on phase 2 (from 15 to 28 days. Except for the piglets in the control diet, all other animals were fed a starter diet with 2.5% of SDPP and 2.5% of spray-dried red blood cell (SDBC during 15 to 28-day-post weaning period. The diets were formulated to contain in the phases 1 and 2, respectively, 1.4 and 1.2% of lysine, .54 and .42% of methionine, and 15

  3. Emission characteristics of kerosene-air spray combustion with plasma assistance

    Directory of Open Access Journals (Sweden)

    Xingjian Liu

    2015-09-01

    Full Text Available A plasma assisted combustion system for combustion of kerosene-air mixtures was developed to study emission levels of O2, CO2, CO, and NOx. The emission measurement was conducted by Testo 350-Pro Flue Gas Analyzer. The effect of duty ratio, feedstock gas flow rate and applied voltage on emission performance has been analyzed. The results show that O2 and CO emissions reduce with an increase of applied voltage, while CO2 and NOx emissions increase. Besides, when duty ratio or feedstock gas flow rate decreases, the same emission results would appear. The emission spectrum of the air plasma of plasma assisted combustion actuator was also registered to analyze the kinetic enhancement effect of plasma, and the generation of ozone was believed to be the main factor that plasma makes a difference in our experiment. These results are valuable for the future optimization of kerosene-fueled aircraft engine when using plasma assisted combustion devices to exert emission control.

  4. Ultrasound enhanced plasma surface modification at atmospheric pressure

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Singh, Shailendra Vikram; Norrman, Kion

    irradiation, the water contact angle dropped markedly, and tended to decrease furthermore at higher power. The ultrasonic irradiation during the plasma treatment consistently improved the wettability. Oxygen containing polar functional groups were introduced at the surface by the plasma treatment......, and the oxidation was enhanced by the ultrasonic irradiation, indicating that the adhesive property would be improved....

  5. Cold plasma source for bacterial inactivation at atmospheric pressure

    DEFF Research Database (Denmark)

    Chen, Weifeng; Stamate, Eugen; Mejlholm, Ole

    plasma treatment conditions (e.g. power, frequency, time). Preliminary experiments were also performed to evaluate the eect of plasma treatment time on the reduction of the concentration of microorganisms (Lactobacillus sakei and Photobacterium phosphoreum) on inoculated slides of Long & Hammer agar....... The results show that the concentration of Lb. sakei on agar slides was reduced signicantly (P phosphoreum to below the detection limit...

  6. Generation of uniform atmospheric pressure argon glow plasma by ...

    Indian Academy of Sciences (India)

    3Plasma Technology Research Centre, Physics Department, University of Malaya,. 50603 Kuala Lumpur, Malaysia. ∗ ... as well as in remediation of the environment and water treatment [1–6]. The interest ... uniform plasma treatment which is necessary for the deposition of homogeneous thin film and uniform surface ...

  7. On the Validity of Continuum Computational Fluid Dynamics Approach Under Very Low-Pressure Plasma Spray Conditions

    Science.gov (United States)

    Ivchenko, Dmitrii; Zhang, Tao; Mariaux, Gilles; Vardelle, Armelle; Goutier, Simon; Itina, Tatiana E.

    2018-01-01

    Plasma spray physical vapor deposition aims to substantially evaporate powders in order to produce coatings with various microstructures. This is achieved by powder vapor condensation onto the substrate and/or by deposition of fine melted powder particles and nanoclusters. The deposition process typically operates at pressures ranging between 10 and 200 Pa. In addition to the experimental works, numerical simulations are performed to better understand the process and optimize the experimental conditions. However, the combination of high temperatures and low pressure with shock waves initiated by supersonic expansion of the hot gas in the low-pressure medium makes doubtful the applicability of the continuum approach for the simulation of such a process. This work investigates (1) effects of the pressure dependence of thermodynamic and transport properties on computational fluid dynamics (CFD) predictions and (2) the validity of the continuum approach for thermal plasma flow simulation under very low-pressure conditions. The study compares the flow fields predicted with a continuum approach using CFD software with those obtained by a kinetic-based approach using a direct simulation Monte Carlo method (DSMC). It also shows how the presence of high gradients can contribute to prediction errors for typical PS-PVD conditions.

  8. On the Validity of Continuum Computational Fluid Dynamics Approach Under Very Low-Pressure Plasma Spray Conditions

    Science.gov (United States)

    Ivchenko, Dmitrii; Zhang, Tao; Mariaux, Gilles; Vardelle, Armelle; Goutier, Simon; Itina, Tatiana E.

    2017-11-01

    Plasma spray physical vapor deposition aims to substantially evaporate powders in order to produce coatings with various microstructures. This is achieved by powder vapor condensation onto the substrate and/or by deposition of fine melted powder particles and nanoclusters. The deposition process typically operates at pressures ranging between 10 and 200 Pa. In addition to the experimental works, numerical simulations are performed to better understand the process and optimize the experimental conditions. However, the combination of high temperatures and low pressure with shock waves initiated by supersonic expansion of the hot gas in the low-pressure medium makes doubtful the applicability of the continuum approach for the simulation of such a process. This work investigates (1) effects of the pressure dependence of thermodynamic and transport properties on computational fluid dynamics (CFD) predictions and (2) the validity of the continuum approach for thermal plasma flow simulation under very low-pressure conditions. The study compares the flow fields predicted with a continuum approach using CFD software with those obtained by a kinetic-based approach using a direct simulation Monte Carlo method (DSMC). It also shows how the presence of high gradients can contribute to prediction errors for typical PS-PVD conditions.

  9. Perspective: The physics, diagnostics, and applications of atmospheric pressure low temperature plasma sources used in plasma medicine

    Science.gov (United States)

    Laroussi, M.; Lu, X.; Keidar, M.

    2017-07-01

    Low temperature plasmas have been used in various plasma processing applications for several decades. But it is only in the last thirty years or so that sources generating such plasmas at atmospheric pressure in reliable and stable ways have become more prevalent. First, in the late 1980s, the dielectric barrier discharge was used to generate relatively large volume diffuse plasmas at atmospheric pressure. Then, in the early 2000s, plasma jets that can launch cold plasma plumes in ambient air were developed. Extensive experimental and modeling work was carried out on both methods and much of the physics governing such sources was elucidated. Starting in the mid-1990s, low temperature plasma discharges have been used as sources of chemically reactive species that can be transported to interact with biological media, cells, and tissues and induce impactful biological effects. However, many of the biochemical pathways whereby plasma affects cells remain not well understood. This situation is changing rather quickly because the field, known today as "plasma medicine," has experienced exponential growth in the last few years thanks to a global research community that engaged in fundamental and applied research involving the use of cold plasma for the inactivation of bacteria, dental applications, wound healing, and the destruction of cancer cells/tumors. In this perspective, the authors first review the physics as well as the diagnostics of the principal plasma sources used in plasma medicine. Then, brief descriptions of their biomedical applications are presented. To conclude, the authors' personal assessment of the present status and future outlook of the field is given.

  10. Effect of Atmospheric Pressure Plasma Modification on Polyimide and Adhesive Joining with Titanium

    Science.gov (United States)

    Akram, M.; Jansen, K. M. B.; Ernst, L. J.; Bhowmik, S.; Ajeesh, G.; Ahmed, S.; Chakraborty, D.

    2015-10-01

    This investigation highlights the effect of surface modification on polyimide by atmospheric pressure plasma treatment with different exposure time. Surface modification of polymer by plasma treatment essentially creates physical and chemical changes such as cross-linking and formation of free radicals. It also forms oxygen functionalization in the form of polar groups on polymer surface, hence improving the wetting and adhesion properties. It is observed that surface energy of the polymer increases with increasing exposure time of atmospheric pressure plasma. However, prolonged exposure time of plasma results in deterioration of the surface layer of polyimide resulting in degradation and embrittlement. Scanning electron microscopy and atomic force microscopy analysis reveal that there is a considerable morphological change on the polymer surface due to atmospheric pressure plasma treatment. X-ray photo electron spectroscopy analysis reveals that the oxygen functionalities of polymer surface increases significantly when polyimide is exposed to atmospheric pressure plasma. Untreated and atmospheric pressure plasma-treated polyimide sheet are adhesive bonded by employing polyimide adhesive as well as with titanium substrate. Due to surface modification of polyimide, it is observed that there is a significant increase in lap shear tensile strength, and therefore, this technology is highly acceptable for aviation and space applications.

  11. Cold Atmospheric Plasma Manipulation of Proteins in Food Systems

    DEFF Research Database (Denmark)

    Tolouie, Haniye; Hashemi, Maryam; Mohammadifar, Mohammad Amin

    2017-01-01

    of plasma on the conformation and function of proteins with food origin, especially enzymes and allergens, as well as protein-made packaging films. In enzyme manipulation with plasma, deactivation has been reported to be either partial or complete. In addition, an activity increase has been observed in some...... where there is thermal sensitivity. As it is a very recent application, the impact of cold plasma treatment has been studied on the protein structures of food and pharmaceutical systems, as well as in the packaging industry. Proteins, as a food constituent, play a remarkable role in the techno...... cases. These variations are caused by the effect of different active species of plasma on the enzyme structure and its function. The level and type of variations in the functional properties of food proteins, purified proteins in food, and plasma-treated protein films are affected by a number of control...

  12. A Novel Atmospheric Pressure Plasma Fluidized Bed and Its Application in Mutation of Plant Seeds

    Science.gov (United States)

    Chen, Guang-Liang; Fan, Song-Hua; Li, Chun-Ling; Gu, Wei-Chao; Feng, Wen-Ran; Zhang, Gu-Ling; Wang, Jiu-Li; Latif, K.; Zhang, Shu-Gen; Wang, Zhen-Quan; Han, Er-Li; Fu, Ya-Bo; Yang, Si-Ze

    2005-08-01

    An atmospheric pressure plasma fluidized bed (APPFB) is designed to generate plasma using a dielectric barrier discharge (DBD) with one liquid electrode. In the APPFB system, the physical properties of DBD discharge and its application in plant-seed mutating are studied fundamentally. The results show that the generated plasma is a typical glow discharge free from filament and arc plasma, and the macro-temperature of the plasma fluidized bed is nearly at room temperature. There are no obvious changes in the pimientos when their seeds are treated by APPFB, but great changes are found for coxcombs.

  13. Effects of atmospheric nonthermal plasma on invasion of colorectal cancer cells

    Science.gov (United States)

    Kim, Chul-Ho; Kwon, Seyeoul; Bahn, Jae Hoon; Lee, Keunho; Jun, Seung Ik; Rack, Philip D.; Baek, Seung Joon

    2010-06-01

    The effect that the gas content and plasma power of atmospheric, nonthermal plasma has on the invasion activity in colorectal cancer cells has been studied. Helium and helium plus oxygen plasmas were induced through a nozzle and operated with an ac power of less than 10 kV which exhibited a length of 2.5 cm and a diameter of 3-4 mm in ambient air. Treatment of cancer cells with the plasma jet resulted in a decrease in cell migration/invasion with higher plasma intensity and the addition of oxygen to the He flow gas.

  14. Cellular and molecular responses of Neurospora crassa to non-thermal plasma at atmospheric pressure

    Science.gov (United States)

    Park, Gyungsoon; Ryu, Young H.; Hong, Young J.; Choi, Eun H.; Uhm, Han S.

    2012-02-01

    Filamentous fungi have been rarely explored in terms of plasma treatments. This letter presents the cellular and molecular responses of the filamentous fungus Neurospora crassa to an argon plasma jet at atmospheric pressure. The viability and cell morphology of N. crassa spores exposed to plasma were both significantly reduced depending on the exposure time when treated in water. The intracellular genomic DNA content was dramatically reduced in fungal tissues after a plasma treatment and the transcription factor tah-3 was found to be required for fungal tolerance to a harsh plasma environment.

  15. Atmospheric-Pressure Plasma Jet Surface Treatment for Use in Improving Adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Kuettner, Lindsey Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-06

    Atmospheric-pressure plasma jets (APPJs) are a method of plasma treatment that plays an important role in material processing and modifying surface properties of materials, especially polymers. Gas plasmas react with polymer surfaces in numerous ways such as oxidation, radical formation, degradation, and promotion of cross-linking. Because of this, gas and plasma conditions can be explored for chosen processes to maximize desired properties. The purpose of this study is to investigate plasma parameters in order to modify surface properties for improved adhesion between aluminum and epoxy substrates using two types of adhesives. The background, results to date, and future work will be discussed.

  16. Cold atmospheric pressure plasma treatment of ready-to-eat meat

    DEFF Research Database (Denmark)

    Röd, Sara Katrine Solhøj; Hansen, Flemming; Leipold, Frank

    Sliced ready-to-eat (RTE) meat products are susceptible to growth of the foodborne pathogenic bacterium, Listeria monocytogenes. Cold atmospheric pressure plasma (CAPP) may be applicable for surface decontamination in sealed bags thus avoiding recontamination. Plasmas (Fig. 1), created in neutral...

  17. Effect of Atmospheric Pressure Plasma Modification on Polyimide and Adhesive Joining with Titanium

    NARCIS (Netherlands)

    Akram, M.; Jansen, K.M.B.; Ernst, L.J.; Bhowmik, S.; Ajeesh, G.; Ahmed, S.; Chakraborty, D.

    2015-01-01

    This investigation highlights the effect of surface modification on polyimide by atmospheric pressure plasma treatment with different exposure time. Surface modification of polymer by plasma treatment essentially creates physical and chemical changes such as cross-linking and formation of free

  18. Effect of precursor solutions on ZnO film via solution precursor plasma spray and corresponding gas sensing performances

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Z.X., E-mail: zexin.yu@utbm.fr [Univ Bourgogne Franche Comte, CNRS, Lab ICB, UMR 6303, Site UTBM, F-90010 Belfort (France); Ma, Y.Z., E-mail: yangzhou.ma@outlook.com [School of Materials Science and Engineering, Anhui University of Technology, Ma’anshan 243002 (China); Zhao, Y.L. [Univ Bourgogne Franche Comte, CNRS, Lab ICB, UMR 6303, Site UTBM, F-90010 Belfort (France); Huang, J.B.; Wang, W.Z. [Key Lab of Safety Science of Pressurized System, Ministry of Education, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237 (China); Moliere, M.; Liao, H.L. [Univ Bourgogne Franche Comte, CNRS, Lab ICB, UMR 6303, Site UTBM, F-90010 Belfort (France)

    2017-08-01

    Highlights: • C-axis preferential oriented grown ZnO films were firstly deposited via SPPS with different solutions. • ZnO films were hydrophobic due to cauliflower and honeycomb-like surface morphologies with high surface specific area. • Gas detecting performance of (002) plane oriented ZnO was predicted and compared by “first principle calculation method”. - Abstract: Solution precursor plasma spraying (SPPS) as a novel thermal spray method was employed to deposit nano-structured ZnO thin film using different formulations of the precursor solution. This article focuses on the influence of the solution composition on the preferential orientation of crystal growth, on crystal size and surface morphology of the resulting ZnO films. The trend of preferential growth along (002) lattice plane of ZnO film was studied by slow scanning X-ray diffraction using a specific coefficient P{sub (002).} It appears that the thermal spray process promotes the buildup of ZnO films preferentially oriented along the c-axis. The shape of single particle tends to change from round shaped beads to hexagonal plates by increasing the volume ratio of ethanol in the solvent. Both cauliflower and honeycomb-like surface morphologies featuring high specific surface area and roughness were obtained through the SPPS process by varying solution composition. These ZnO films are hydrophobic with contact angle as high as 136°, which is seemingly associated with micro reliefs developing high surface specific area. Then the gas sensing performances of ZnO films preferentially oriented along (002) face were tentatively predicted using the “first principle calculation method” and were compared with those of conventional films that are mainly oriented along the (101) face. The (002) face displays better hydrogen adsorption capability than the (101) face with much larger resulting changes in electrical resistance. In conclusion, the c-axis oriented ZnO films obtained through SSPS have

  19. Effect of non-thermal atmospheric pressure plasma jet on human breast cancer cells

    Science.gov (United States)

    Mirpour, Shahriar; Nikkhah, Maryam; Pirouzmand, Somaye; Ghomi, Hamid Reza

    2012-10-01

    Nowadays, Non-thermal plasma enjoy a wide range of applications in biomedical fields such as Sterilization, Wound healing, Cancer treatment and etc. The aim of this paper is to study the effect of non-thermal atmospheric pressure plasma jet on breast cancer (MCF-7) cells. In this regard the effect of plasma on death of the cancer cells are explored experimentally. The plasma in this discharge is created by pulsed dc high voltage power supply with repetition rate of several tens of kilohertz which led to the inductively coupled plasma. The pure helium gas were used for formation of the plasma jet. MTT assay were used for quantification of death cells. The results showed that the cells death rate increase with plasma exposure time. This study confirm that plasma jet have significant effect on treatment of human breast cancer cells.

  20. Decontamination of objects in a sealed container by means of atmospheric pressure plasmas

    DEFF Research Database (Denmark)

    Leipold, Frank; Schultz-Jensen, Nadja; Kusano, Yukihiro

    2011-01-01

    . The ambient atmosphere was air at atmospheric pressure. A plasma is generated inside the bag forming ozone from the oxygen. The maximum ozone concentration in the bag was found to be 140 ppm. A log 6 reduction of L. innocua is obtained after 15 min of exposure time. The temperature of the slides after...

  1. Reactive species in non-equilibrium atmospheric-pressure plasmas: Generation, transport, and biological effects

    Energy Technology Data Exchange (ETDEWEB)

    Lu, X., E-mail: luxinpei@hotmail.com [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China); Naidis, G.V. [Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412 (Russian Federation); Laroussi, M. [Plasma Engineering & Medicine Institute, Old Dominion University, Norfolk, VA 23529 (United States); Reuter, S. [Leibniz Institute for Plasma Science and Technology, Felix-Hausdorff-Strasse 2, 17489 Greifswald (Germany); Graves, D.B. [Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720 (United States); Ostrikov, K. [Institute for Future Environments, Queensland University of Technology, Brisbane, QLD 4000 (Australia); School of Physics, Chemistry, and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD 4000 (Australia); Commonwealth Scientific and Industrial Research Organization, P.O.Box 218, Lindfield, NSW 2070 (Australia); School of Physics, The University of Sydney, Sydney, NSW 2006 (Australia)

    2016-05-04

    Non-equilibrium atmospheric-pressure plasmas have recently become a topical area of research owing to their diverse applications in health care and medicine, environmental remediation and pollution control, materials processing, electrochemistry, nanotechnology and other fields. This review focuses on the reactive electrons and ionic, atomic, molecular, and radical species that are produced in these plasmas and then transported from the point of generation to the point of interaction with the material, medium, living cells or tissues being processed. The most important mechanisms of generation and transport of the key species in the plasmas of atmospheric-pressure plasma jets and other non-equilibrium atmospheric-pressure plasmas are introduced and examined from the viewpoint of their applications in plasma hygiene and medicine and other relevant fields. Sophisticated high-precision, time-resolved plasma diagnostics approaches and techniques are presented and their applications to monitor the reactive species and plasma dynamics in the plasma jets and other discharges, both in the gas phase and during the plasma interaction with liquid media, are critically reviewed. The large amount of experimental data is supported by the theoretical models of reactive species generation and transport in the plasmas, surrounding gaseous environments, and plasma interaction with liquid media. These models are presented and their limitations are discussed. Special attention is paid to biological effects of the plasma-generated reactive oxygen and nitrogen (and some other) species in basic biological processes such as cell metabolism, proliferation, survival, etc. as well as plasma applications in bacterial inactivation, wound healing, cancer treatment and some others. Challenges and opportunities for theoretical and experimental research are discussed and the authors’ vision for the emerging convergence trends across several disciplines and application domains is presented to

  2. Porcine intact and wounded skin responses to atmospheric nonthermal plasma.

    Science.gov (United States)

    Wu, Andrew S; Kalghatgi, Sameer; Dobrynin, Danil; Sensenig, Rachel; Cerchar, Ekaternia; Podolsky, Erica; Dulaimi, Essel; Paff, Michelle; Wasko, Kimberly; Arjunan, Krishna Priya; Garcia, Kristin; Fridman, Gregory; Balasubramanian, Manjula; Ownbey, Robert; Barbee, Kenneth A; Fridman, Alexander; Friedman, Gary; Joshi, Suresh G; Brooks, Ari D

    2013-01-01

    Thermal plasma is a valued tool in surgery for its coagulative and ablative properties. We suggested through in vitro studies that nonthermal plasma can sterilize tissues, inactive pathogens, promote coagulation, and potentiate wound healing. The present research was undertaken to study acute toxicity in porcine skin tissues. We demonstrate that floating electrode-discharge barrier discharge (FE-DBD) nonthermal plasma is electrically safe to apply to living organisms for short periods. We investigated the effects of FE-DBD plasma on Yorkshire pigs on intact and wounded skin immediately after treatment or 24h posttreatment. Macroscopic or microscopic histological changes were identified using histological and immunohistochemical techniques. The changes were classified into four groups for intact skin: normal features, minimal changes or congestive changes, epidermal layer damage, and full burn and into three groups for wounded skin: normal, clot or scab, and full burn-like features. Immunohistochemical staining for laminin layer integrity showed compromise over time. A marker for double-stranded DNA breaks, γ-H2AX, increased over plasma-exposure time. These findings identified a threshold for plasma exposure of up to 900s at low power and <120s at high power. Nonthermal FE-DBD plasma can be considered safe for future studies of external use under these threshold conditions for evaluation of sterilization, coagulation, and wound healing. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. Tungsten coating by ATC plasma spraying on CFC for WEST tokamak

    Science.gov (United States)

    Firdaouss, M.; Desgranges, C.; Hernandez, C.; Mateus, C.; Maier, H.; Böswirth, B.; Greuner, H.; Samaille, F.; Bucalossi, J.; Missirlian, M.

    2017-12-01

    In the field of fusion experiments using a tokamak, the plasma facing components (PFC) are the closest object to the hot plasma. Due to the plasma-wall interaction, the material composing the PFC may enter the plasma and disturb the experiments. In the past, the main material for PFC was carbon (CFC, graphite), while the future reactors like ITER will be fully metallic, in particular tungsten. The Tore Supra tokamak has been transformed in an x-point divertor fusion device within the frame of the WEST (W (tungsten) Environment in Steady-state Tokamak) project in order to have plasma conditions close to those expected in ITER. The PFC other than the divertor has been coated with W to transform Tore Supra into a fully metallic environment. Different coating techniques have been selected for different kind of PFC. This paper gives an overview on the coating process used for the antennae protection limiter, the associated validation programme and concludes on the adequacy of the W coating with the WEST experimental programme requirements and gives perspectives on the development to be pursued.

  4. Characterization of an atmospheric pressure air plasma source for polymer surface modification

    Science.gov (United States)

    Yang, Shujun; Tang, Jiansheng

    2013-10-01

    An atmospheric pressure air plasma source was generated through dielectric barrier discharge (DBD). It was used to modify polyethyleneterephthalate (PET) surfaces with very high throughput. An equivalent circuit model was used to calculate the peak average electron density. The emission spectrum from the plasma was taken and the main peaks in the spectrum were identified. The ozone density in the down plasma region was estimated by Absorption Spectroscopy. NSF and ARC-ODU

  5. Atmospheric-pressure dielectric barrier discharge (DBD) in air : plasma characterisation for skin therapy

    OpenAIRE

    Rajasekaran, Priyadarshini

    2011-01-01

    A pulsed atmospheric-pressure dielectric barrier discharge (DBD) device operating in air is investigated for medical applications such as for skin disinfection and promotion of wound healing. The device ignites plasma on objects of high capacitance such as the human body and with grounded electrodes. Plasma parameters such as electron density and electron distribution function are determined. Plasma chemical kinetics is simulated and the production of biologically-useful molecules...

  6. High-performance simulations for atmospheric pressure plasma reactor

    Science.gov (United States)

    Chugunov, Svyatoslav

    Plasma-assisted processing and deposition of materials is an important component of modern industrial applications, with plasma reactors sharing 30% to 40% of manufacturing steps in microelectronics production. Development of new flexible electronics increases demands for efficient high-throughput deposition methods and roll-to-roll processing of materials. The current work represents an attempt of practical design and numerical modeling of a plasma enhanced chemical vapor deposition system. The system utilizes plasma at standard pressure and temperature to activate a chemical precursor for protective coatings. A specially designed linear plasma head, that consists of two parallel plates with electrodes placed in the parallel arrangement, is used to resolve clogging issues of currently available commercial plasma heads, as well as to increase the flow-rate of the processed chemicals and to enhance the uniformity of the deposition. A test system is build and discussed in this work. In order to improve operating conditions of the setup and quality of the deposited material, we perform numerical modeling of the plasma system. The theoretical and numerical models presented in this work comprehensively describe plasma generation, recombination, and advection in a channel of arbitrary geometry. Number density of plasma species, their energy content, electric field, and rate parameters are accurately calculated and analyzed in this work. Some interesting engineering outcomes are discussed with a connection to the proposed setup. The numerical model is implemented with the help of high-performance parallel technique and evaluated at a cluster for parallel calculations. A typical performance increase, calculation speed-up, parallel fraction of the code and overall efficiency of the parallel implementation are discussed in details.

  7. Karakterizacija WCCo/NiCrBSi prevlake otporne na habanje / Characterization of wear resistant plasma sprayed WCCo/NiCrBSi self-fluxing coatings

    Directory of Open Access Journals (Sweden)

    Mihailo R. Mrdak

    2010-04-01

    Full Text Available U radu su analizirani mikrostruktura, mehaničke i tribološke karakteristike (APS prevlake WCCoNiCrBSi koja se primenjuje za reparaciju cilindara nosne noge helikoptera. Tribološka procena prevlake određena je primenom tribometra blok-na-prstenu. Spregnuti materijalblokovi sa prevlakom ispitani su na okaljenom i poboljšanom čeličnom prstenu. Za ukupno odstojanje od 3000 m bili su konstantna brzina 0,5 m/s i opterećenje 400 N. Prednost primene ove prevlake je u značajnom produženju resursa delova uz smanjenje troškova eksploatacije i održavanja. / In this paper, the microstructural, mechanical and tribological properties of WCCoNiCrBSi thermal spray coatings, applied to repair the cylinders of helicopter nasal feet, were analyzed. The process used for coating deposition on steel substrate was the Atmospheric Plasma Spraying (APS.The plasma spray process is a procedure widely used for applying coatings with increased resistance to wear. The combination of WCCo and NiCrBSi powders produced coatings for the protection of metal parts exposed to wear abrasion, erosion and cavitation to 540°C. The WCCoNiCrBSi 50/50% powder is specially developed for the production of coatings of high cohesion and adhesive strength. The coatings are very dense, hard and smooth. Microstructures present in the layers are tungsten carbides and chromium layers that increase resistance to wear and abrasion. Powder is deposited on the substrate rugged with Al2O3. The substrates were heated at temperatures up to 200°C. Powder deposition was performed with the optimal deposition parameters The microstructure and micro hardness of the coating layer was investigated on the cross section of samples using the Pratt & Whitney standard. Micro hardness was tested using the Vickers scale with a load of 300g. The microstructure of the layers was investigated on an optical microscope (OM with a magnification of 400X. Testing of bond strength between coatings and substrates

  8. Solid Carbon Produced in an Inductively Coupled Plasma Torch with a Titan Like Atmosphere

    Directory of Open Access Journals (Sweden)

    D. Vacher

    2013-01-01

    Full Text Available Solid carbon is deposited on the surfaces of an inductively coupled plasma torch operating with a Titan like atmosphere plasma gas. The frame of the initial research is the study of the radiative properties of plasma encountered around a spacecraft during its hypersonic entry in upper layers of planetary atmosphere. Deposition of carbon is observed not only on the quartz tube outside the inductor but also on the ceramic protection of the torch injector. Carbon exhibits two types of morphology more or less dense and it is analyzed by various analytic devices as MEB, SEM, TEM, EDS and Raman spectroscopy. The gathered carbon powder shows the presence of nanostructured particles.

  9. Atmospheric Pressure Low Temperature Plasma System for Additive Manufacturing

    Science.gov (United States)

    Burnette, Matthew; Staack, David

    2016-09-01

    There is growing interest in using plasmas for additive manufacturing, however these methods use high temperature plasmas to melt the material. We have developed a novel technique of additive manufacturing using a low temperature dielectric barrier discharge (DBD) jet. The jet is attached to the head of a 3D printer to allow for precise control of the plasma's location. Various methods are employed to deposit the material, including using a vaporized precursor or depositing a liquid precursor directly onto the substrate or into the plasma via a nebulizer. Various materials can be deposited including metals (copper using copper (II) acetylacetonate), polymers (PMMA using the liquid monomer), and various hydrocarbon compounds (using alcohols or a 100% methane DBD jet). The rastering pattern for the 3D printer was modified for plasma deposition, since it was originally designed for thermoplastic extrusion. The design constraints for fill pattern selection for the plasma printer are influenced by substrate heating, deposition area, and precursor consumption. Depositions onto pressure and/or temperature sensitive substrates can be easily achieved. Deposition rates range up to 0.08 cm3/hr using tris(2-methoxyethoxy)(vinyl)silane, however optimization can still be done on the system to improve the deposition rate. For example higher concentration of precursor can be combined with faster motion and higher discharge powers to increase the deposition rate without overheating the substrate.

  10. Zero voltage switching driver and flyback transformer for generation of atmospheric pressure plasma jet

    Science.gov (United States)

    Zin, Rosnah Mohd; Soon, Chin Fhong; Sani, Mohd Zuhri Ab; Rizon, Elfa Rizan; Tee, Kian Sek; Ahmad, Mohd Khairul; Ahmad, Nabihah@Nornabihah; Jubadi, Warsuzarina Mat; Nayan, Nafarizal

    2017-09-01

    There are increasing interests in the application of cold atmospheric plasma device for the application in surface science and medical field. Numerous studies focused on the effects of plasma emission onto living organisms. This report presents the application of a power driver circuit for induction of cold atmospheric plasma (CAP). The system consists of a resonant inverter of Zero Voltage Switching (ZVS) circuit powered by a 12Vdc input voltage which is coupled to a flyback transformer in generation of high voltage up to 24.5 kV. The output voltage from the ZVS driver and flyback transformer to the plasma torch (quartz tube) was determined using Falstad circuit simulation. The simulation on the waveforms generated from the ZVS circuit correlated well with the actual voltage measurement at the output of the ZVS circuit. The peak voltage dropped across a parallel capacitor coupled to the flyback transformer is approximately 36 V. The atmospheric pressure plasma jet (APPJ) purged with Argon gas at a flow rate of 50 l/min was exposed to a leaf for 5 seconds. This created pin holes in the exposed area of the leaf indicating high temperature was induced at the focused spot of the plasma. An atmospheric pressure plasma jet (APPJ) system has been developed for with potential application in destructive medicine.

  11. Cold atmospheric plasma manipulation of proteins in food systems.

    Science.gov (United States)

    Tolouie, Haniye; Mohammadifar, Mohammad Amin; Ghomi, Hamid; Hashemi, Maryam

    2017-06-14

    Plasma processing has been getting a lot of attention in recent applications as a novel, eco-friendly, and highly efficient approach. Cold plasma has mostly been used to reduce microbial counts in foodstuff and biological materials, as well as in different levels of packaging, particularly in cases where there is thermal sensitivity. As it is a very recent application, the impact of cold plasma treatment has been studied on the protein structures of food and pharmaceutical systems, as well as in the packaging industry. Proteins, as a food constituent, play a remarkable role in the techno-functional characteristics of processed foods and/or the physico-chemical properties of protein-based films. At the same time, some proteins are responsible for reduction in quality and nutritional value, and/or causing allergic reactions in the human body. This study is a review of the influences of different types of plasma on the conformation and function of proteins with food origin, especially enzymes and allergens, as well as protein-made packaging films. In enzyme manipulation with plasma, deactivation has been reported to be either partial or complete. In addition, an activity increase has been observed in some cases. These variations are caused by the effect of different active species of plasma on the enzyme structure and its function. The level and type of variations in the functional properties of food proteins, purified proteins in food, and plasma-treated protein films are affected by a number of control factors, including treatment power, time, and gas type, as well as the nature of the substance and the treatment environment.

  12. Single channel atmospheric pressure transporting plasma and plasma stream demultiplexing: physical characterization and application to E. coli bacteria inactivation

    Science.gov (United States)

    Valinataj Omran, A.; Sohbatzadeh, F.; Siadati, S. N.; Hosseinzadeh Colagar, A.; Akishev, Y.; Arefi-Khonsari, F.

    2017-08-01

    In this article, we developed transporting plasma sources that operate at atmospheric pressure. The effect of electrode configuration on plasma transporting was investigated. In order to increase the transporting plasma cross-section, we converted a plasma stream into four plasma channels by a cylindrical housing. Electron excitation and rotational temperatures were estimated using optical emission spectroscopy. Furthermore, the electrical and temporal characteristics of the plasma, discharge power and charge deposition on the target were investigated. The propagation characteristics of single and multi-channel transporting plasma were compared with the same cross-sectional area. Two configurations for multi-channels were designed for this purpose. Escherichia coli bacteria were exposed to the single and multi-channel transporting discharge for different time durations. After exposure, the results indicated that the inactivation zones were significantly increased by a multi-channel transporting plasma. Finally, E. coli inactivation by those plasma apparatuses was compared with that of several standard antimicrobial test discs such as Gentamicin, Tetracycline, Amoxicillin and Cefixime.

  13. Kinetic Theory of Meteor Plasma in the Earth's atmosphere: Implications for Radar Head Echo

    Science.gov (United States)

    Dimant, Y. S.; Oppenheim, M. M.

    2015-12-01

    Every second millions of tiny meteoroids hit the Earth from space, vast majority too small to be observed visually. However, radars detect the plasma they generate and use the collected data to characterize the incoming meteoroids and the atmosphere in which they disintegrate. This diagnostics requires a detailed quantitative understanding of formation of the meteor plasma and how it interacts with the Earth's atmosphere. Fast-descending meteoroids become detectable to radars after they heat due to collisions with atmospheric molecules sufficiently and start ablating. The ablated material then collides into atmospheric molecules and forms plasma around the meteoroid. Reflection of radar pulses from this plasma produces a localized signal called a head echo often accompanied by a much longer non-specular trail (see the Figure). Using first principles, we have developed a consistent collisional kinetic theory of the near-meteoroid plasma responsible for the radar head echo. This theory produces analytic expressions describing the ion and neutral velocity distributions along with the detailed 3-D spatial structure of the near-meteoroid plasma. These expressions predict a number of unexpected features such as shell-like velocity distributions. This theory shows that the meteoroid plasma develops over a length-scale close to the ion mean free path with a strongly non-Maxwellian velocity distribution. The spatial distribution of the plasma density shows significant deviations from a Gaussian law usually employed in head-echo modeling. This analytical model will serve as a basis for a more accurate quantitative interpretation of radar measurements, estimates of the ionization efficiency, and should help calculate meteoroid and atmosphere parameters from radar head-echo observations. This theory could also help clarify the physical nature of electromagnetic pulses observed during recent meteor showers and associated with the passage of fast-moving meteors through the

  14. Effects of cold atmospheric plasma generated in DI water on Cancer cells

    CERN Document Server

    Chen, Zhitong; Cheng, Xiaoqian; Gjika, Eda; Keidar, Michael

    2016-01-01

    Cold atmospheric plasma (CAP) has been shown to affect cells not only directly, but also by means of indirect treatment with previously prepared plasma stimulated solution. The objective of this study is to reveal the effects of plasma-stimulated media (PSM) on breast cancer cells (MDA-MB-231) and gastric cancer cells (NCl-N87). In our experiments, cold atmospheric plasma is generated in water using helium as carrier gas. The plasma generated in DI water during a 30-minute treatment had the strongest affect in inducing apoptosis in cultured human breast and gastric cancer cells. This result can be attributed to the presence of reactive oxygen species (ROS) and reactive nitrogen species (RNS) produced in water during treatment.

  15. Structure and electronic properties features of amorphous chalhogenide semiconductor films prepared by ion-plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Korobova, N., E-mail: korobova3@mail.ru; Timoshenkov, S. [Department of Microelectronics, National Research University of Electronic Technology (MIET), Zelenograd (Russian Federation); Almasov, N.; Prikhodko, O. [al-Farabi Kazakh National University, Almaty (Kazakhstan); Tsendin, K. [Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg (Russian Federation)

    2014-10-21

    Structure of amorphous chalcogenide semiconductor glassy As-S-Se films, obtained by high-frequency (HF) ion-plasma sputtering has been investigated. It was shown that the length of the atomic structure medium order and local structure were different from the films obtained by thermal vacuum evaporation. Temperature dependence of dark conductivity, as well as the dependence of the spectral transmittance has been studied. Conductivity value was determined at room temperature. Energy activation conductivity and films optical band gap have been calculated. Temperature and field dependence of the drift mobility of charge carriers in the HF As-S-Se films have been shown. Bipolarity of charge carriers drift mobility has been confirmed. Absence of deep traps for electrons in the As{sub 40}Se{sub 30}S{sub 30} spectrum of localized states for films obtained by HF plasma ion sputtering was determined. Bipolar drift of charge carriers was found in amorphous As{sub 40}Se{sub 30}S{sub 30} films obtained by ion-plasma sputtering of high-frequency, unlike the films of these materials obtained by thermal evaporation.

  16. Effects of MgO and SiO2 on Plasma-Sprayed Hydroxyapatite Coating: An in Vivo Study in Rat Distal Femoral Defects.

    Science.gov (United States)

    Ke, Dongxu; Robertson, Samuel F; Dernell, William S; Bandyopadhyay, Amit; Bose, Susmita

    2017-08-09

    Plasma-sprayed hydroxyapatite (HA)-coated titanium implants have been widely used in orthopedic applications due to their inheritance of an excellent mechanical property from titanium and great osteoconductivity from HA. However, the lack of osteoinductivity limits their further applications. In this study, 1 wt % MgO and 0.5 wt % SiO2 were mixed with HA for making plasma-sprayed coatings on titanium implants. Plasma-sprayed HA- and MgO/SiO2-HA-coated titanium implants showed adhesive bond strengths of 25.73 ± 1.92 and 23.44 ± 2.89 MPa, respectively. The presence of MgO and SiO2 significantly increased the osteogenesis, osseointegration, and bone mineralization of HA-coated titanium implants by the evaluation of their histomorphology after 6, 10, and 14 weeks of implantation in rat distal femoral defects. Implant pushout tests also showed a shear modulus of 149.83 ± 3.69 MPa for MgO/SiO2-HA-coated implants after 14 weeks of implantation, compared to 52.68 ± 10.41 MPa for uncoated implants and 83.92 ± 3.68 MPa for pure HA-coated implants; These are differences in the shear modulus of 96% and 56.4%, respectively. This study assesses for the first time the quality of the bone-implant interface of induction plasma-sprayed MgO and SiO2 binary-doped HA coatings on load-bearing implants compared to bare titanium and pure HA coatings in a quantitative manner. Relating the osseointegration and interface shear modulus to the quality of implant fixation is critical to the advancement and implementation of HA-coated orthopedic implants.

  17. Surface properties and hydrophobic recovery of polymers treated by atmospheric-pressure plasma

    Science.gov (United States)

    Borcia, C.; Punga, I. L.; Borcia, G.

    2014-10-01

    This paper provides an analysis on the relation between plasma effects on polymers exposed to inert gas atmospheric-pressure plasma, polymer structure characteristics and surface recovery during post-processing ageing. Polymers offering variety of structure, functionality, degree of oxidation, polarity, crystallinity are tested, using contact angle, XPS, XRD and solvent absorption measurement, thus exploring the relationship linking the surface polarity, the chemical structure and composition contribution in the combined functionalization/crosslinking surface modification mechanisms of plasma-exposed polymers. The limiting level of modification attainable, the surface stability and the factors controlling these are examined, concluding on the plasma capacity to provide operational stability for modified polymer surfaces.

  18. Micro-morphometric assessment of titanium plasma-sprayed coating removal using burs for the treatment of peri-implant disease.

    Science.gov (United States)

    Rimondini, L; Cicognani Simoncini, F; Carrassi, A

    2000-04-01

    This study evaluated, in vitro, the effectiveness of diamond and carbide burs, and bur sequences to remove the plasma-sprayed titanium coating from IMZ fixture surfaces. Fifteen polishing procedures were tested. They included the use of 12, 16, 30 bladed carbide burs or bevered carbide burs and 30, 15, 8 microns mean-particles-size diamond burs. The treated surfaces were evaluated with profilometer and SEM. Worn burs and titanium debris produced by the grinding were observed with SEM. All procedures produce smoother surfaces than baseline plasma-sprayed surfaces for both Ra and Rz(DIN) parameters (P < 0.001). A roughening effect of the 8 microns mean-grit diamond bur and 30 bladed burs were noted. The single carbide burs produce polished surfaces affected by waviness. Waviness was minimized by sequence or diamond bur use. The carbide bur blades were variously damaged after their use. In contrast, the grit of diamond burs was observed to be clogged by titanium debris whose amount seemed to be inversely related to the diamond mean particle size. Debris produced by diamond burs was granular whereas that produced by carbide bladed burs showed needle or flake morphology. In conclusion, the most effective titanium plasma sprayed removal were obtained by 30 microns and 15 microns mean-particle-size diamond burs, i.e. 30 microns plus 15 microns diamond burs and carbide 12 plus 16 bladed burs used in sequence.

  19. Porous tantalum coatings prepared by vacuum plasma spraying enhance bmscs osteogenic differentiation and bone regeneration in vitro and in vivo.

    Science.gov (United States)

    Tang, Ze; Xie, Youtao; Yang, Fei; Huang, Yan; Wang, Chuandong; Dai, Kerong; Zheng, Xuebin; Zhang, Xiaoling

    2013-01-01

    Tantalum, as a potential metallic implant biomaterial, is attracting more and more attention because of its excellent anticorrosion and biocompatibility. However, its significantly high elastic modulus and large mechanical incompatibility with bone tissue make it unsuitable for load-bearing implants. In this study, porous tantalum coatings were first successfully fabricated on titanium substrates by vacuum plasma spraying (VPS), which would exert the excellent biocompatibility of tantalum and alleviate the elastic modulus of tantalum for bone tissue. We evaluated cytocompatibility and osteogenesis activity of the porous tantalum coatings using human bone marrow stromal cells (hBMSCs) and its ability to repair rabbit femur bone defects. The morphology and actin cytoskeletons of hBMSCs were observed via electron microscopy and confocal, and the cell viability, proliferation and osteogenic differentiation potential of hBMSCs were examined quantitatively by PrestoBlue assay, Ki67 immunofluorescence assay, real-time PCR technology and ALP staining. For in vivo detection, the repaired femur were evaluated by histomorphology and double fluorescence labeling 3 months postoperation. Porous tantalum coating surfaces promoted hBMSCs adhesion, proliferation, osteogenesis activity and had better osseointegration and faster new bone formation rate than titanium coating control. Our observation suggested that the porous tantalum coatings had good biocompatibility and could enhance osseoinductivity in vitro and promote new bone formation in vivo. The porous tantalum coatings prepared by VPS is a promising strategy for bone regeneration.

  20. Cyclic delamination behavior of plasma-sprayed hydroxyapatite coating on Ti-6Al-4V substrates in simulated body fluid.

    Science.gov (United States)

    Otsuka, Yuichi; Kawaguchi, Hayato; Mutoh, Yoshiharu

    2016-10-01

    This study aimed to clarify the effect of a simulated body fluid (SBF) on the cyclic delamination behavior of a plasma-sprayed hydroxapatite (HAp) coating. A HAp coating is deposited on the surfaces of surgical metallic materials in order to enhance the bond between human bone and such surfaces. However, the HAp coating is susceptible to delamination by cyclic loading from the patient's gait. Although hip joints are subjected to both positive and negative moments, only the effects of tensile bending stresses on vertical crack propagation behavior have been investigated. Thus, the cyclic delamination behavior of a HAp coating was observed at the stress ratio R=-1 in order to determine the effects of tensile/compressive loading on the delamination behavior. The delamination growth rate increased with SBF immersion, which decreased the delamination life. Raman spectroscopy analysis revealed that the selective phase dissolution in the HAp coating was promoted at interfaces. Finite element analysis revealed that the energy release rate Gmax showed a positive value even in cases with compressive loading, which is a driving force for the delamination of a HAp coating. A prediction model for the delamination growth life was developed that combines a fracture mechanics parameter with the assumed stress-dependent dissolution rate. The predicted delamination life matched the experimental data well in cases of lower stress amplitudes with SBF. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Phosphor-Doped Thermal Barrier Coatings Deposited by Air Plasma Spray for In-Depth Temperature Sensing

    Directory of Open Access Journals (Sweden)

    Di Peng

    2016-09-01

    Full Text Available Yttria-stabilized zirconia (YSZ-based thermal barrier coating (TBC has been integrated with thermographic phosphors through air plasma spray (APS for in-depth; non-contact temperature sensing. This coating consisted of a thin layer of Dy-doped YSZ (about 40 µm on the bottom and a regular YSZ layer with a thickness up to 300 µm on top. A measurement system has been established; which included a portable; low-cost diode laser (405 nm; a photo-multiplier tube (PMT and the related optics. Coating samples with different topcoat thickness were calibrated in a high-temperature furnace from room temperature to around 900 °C. The results convincingly showed that the current sensor and the measurement system was capable of in-depth temperature sensing over 800 °C with a YSZ top layer up to 300 µm. The topcoat thickness was found to have a strong effect on the luminescent signal level. Therefore; the measurement accuracy at high temperatures was reduced for samples with thick topcoats due to strong light attenuation. However; it seemed that the light transmissivity of YSZ topcoat increased with temperature; which would improve the sensor’s performance at high temperatures. The current sensor and the measurement technology have shown great potential in on-line monitoring of TBC interface temperature.

  2. Porous tantalum coatings prepared by vacuum plasma spraying enhance bmscs osteogenic differentiation and bone regeneration in vitro and in vivo.

    Directory of Open Access Journals (Sweden)

    Ze Tang

    Full Text Available Tantalum, as a potential metallic implant biomaterial, is attracting more and more attention because of its excellent anticorrosion and biocompatibility. However, its significantly high elastic modulus and large mechanical incompatibility with bone tissue make it unsuitable for load-bearing implants. In this study, porous tantalum coatings were first successfully fabricated on titanium substrates by vacuum plasma spraying (VPS, which would exert the excellent biocompatibility of tantalum and alleviate the elastic modulus of tantalum for bone tissue. We evaluated cytocompatibility and osteogenesis activity of the porous tantalum coatings using human bone marrow stromal cells (hBMSCs and its ability to repair rabbit femur bone defects. The morphology and actin cytoskeletons of hBMSCs were observed via electron microscopy and confocal, and the cell viability, proliferation and osteogenic differentiation potential of hBMSCs were examined quantitatively by PrestoBlue assay, Ki67 immunofluorescence assay, real-time PCR technology and ALP staining. For in vivo detection, the repaired femur were evaluated by histomorphology and double fluorescence labeling 3 months postoperation. Porous tantalum coating surfaces promoted hBMSCs adhesion, proliferation, osteogenesis activity and had better osseointegration and faster new bone formation rate than titanium coating control. Our observation suggested that the porous tantalum coatings had good biocompatibility and could enhance osseoinductivity in vitro and promote new bone formation in vivo. The porous tantalum coatings prepared by VPS is a promising strategy for bone regeneration.

  3. Bond strength of plasma sprayed ceramic coatings on the phosphated steels

    Directory of Open Access Journals (Sweden)

    P. Pokorny

    2015-04-01

    Full Text Available In the presented work, results of adhesion measurements for different systems of steel sheet-phosphate interlayer-ceramiccoating are described. The interlayers were produced by zinc phosphating; alumina, olivine and zirconiasilica-alumina (e.g. eucor coatings were deposited by water stabilized plasma torch WSP®. However, successful application of the WSP technique depends on the choice of correct deposition parameters preserving the hydrated phosphates from thermal destruction by the molten ceramic particles. For the adhesion measurement ISO 4624standardized test was used. Corrosion resistivity was measured by polarisation resistance and free corrosion potential in 3 % NaCl solution.

  4. Atmospheric pressure plasma jet with high-voltage power supply based on piezoelectric transformer.

    Science.gov (United States)

    Babij, Michał; Kowalski, Zbigniew W; Nitsch, Karol; Silberring, Jerzy; Gotszalk, Teodor

    2014-05-01

    The dielectric barrier discharge plasma jet, an example of the nonthermal atmospheric pressure plasma jet (APPJ), generates low-temperature plasmas that are suitable for the atomization of volatile species and can also be served as an ionization source for ambient mass and ion mobility spectrometry. A new design of APPJ for mass spectrometry has been built in our group. In these plasma sources magnetic transformers (MTs) and inductors are typically used in power supplies but they present several drawbacks that are even more evident when dealing with high-voltage normally used in APPJs. To overcome these disadvantages, high frequency generators with the absence of MT are proposed in the literature. However, in the case of miniaturized APPJs these conventional power converters, built of ferromagnetic cores and inductors or by means of LC resonant tank circuits, are not so useful as piezoelectric transformer (PT) based power converters due to bulky components and small efficiency. We made and examined a novel atmospheric pressure plasma jet with PT supplier served as ionization source for ambient mass spectrometry, and especially mobile spectrometry where miniaturization, integration of components, and clean plasma are required. The objective of this paper is to describe the concept, design, and implementation of this miniaturized piezoelectric transformer-based atmospheric pressure plasma jet.

  5. Efficacy of Atmospheric Pressure Plasma as an Antibacterial Agent Against Enterococcus Faecalis in Vitro

    Science.gov (United States)

    Cao, Yingguang; Yang, Ping; Lu, Xinpei; Xiong, Zilan; Ye, Tao; Xiong, Qing; Sun, Ziyong

    2011-02-01

    Enterococcus faecalis (E. faecalis) is a microorganism that can survive extreme challenges in obturated root canals. The aim of this study was to evaluate the efficacy of a non-thermal atmospheric pressure plasma plume against E. faecalis in vitro. A non-thermal atmospheric pressure plasma jet device which could generate a cold plasma plume carrying a peak current of 300 mA was used. The antibacterial efficacy of this device against E. faecalis and its biofilm under different conditions was detected. The antibacterial efficacy of the plasma against E. faecalis and Staphylococcus aureus (S. aureus) was also evaluated. After plasma treatment, the average diameter of inhibition zone on S. aureus and E. faecalis was 2.62±0.26 cm and 1.06±0.30 cm, respectively (P < 0.05). The diameter was increased with prolongation of the treatment duration. The diameters of inhibition zone of the sealed Petri dishes were larger than those of the uncovered Petri dishes. There was significant difference in colony-forming units between plasma group and control group on E. faecalis biofilm (P < 0.01). The transmission electron microscopy revealed that the ultrastructural changes cytoderm of E. faecalis were observed after treatment for 2 min. It is concluded that the non-thermal atmospheric pressure plasma could serve as an effective adjunct to standard endodontic microbial treatment.

  6. Effects of atmospheric air plasma treatment on interfacial properties of PBO fiber reinforced composites

    Science.gov (United States)

    Zhang, Chengshuang; Li, Cuiyun; Wang, Baiya; Wang, Bin; Cui, Hong

    2013-07-01

    Poly(p-phenylene benzobisoxazole) (PBO) fiber was modified by atmospheric air plasma treatment. The effects of plasma treatment power and speed on both surface properties of PBO fibers and interfacial properties of PBO/epoxy composites were investigated. Surface chemical composition of PBO fibers were analyzed by X-ray photoelectron spectroscopy (XPS). Surface morphologies of the fibers and interface structures of the composites were examined using scanning electron microscopy (SEM). Interfacial adhesion property of the composites was evaluated by interlaminar shear strength (ILSS). Mechanical properties of PBO multifilament were measured by universal testing machine. The results indicate that atmospheric air plasma treatment introduced some polar or oxygen-containing groups to PBO fiber surfaces, enhanced surface roughness and changed surface morphologies of PBO fibers by plasma etching and oxidative reactions. The plasma treatment also improved interfacial adhesion of PBO/epoxy composites but has little effect on tensile properties of PBO multifilament. The ILSS of PBO/epoxy composites increased to 40.0 MPa after atmospheric air plasma treatment with plasma treatment power of 300 W and treatment speed of 6 m/min.

  7. Scrutiny of plasma spraying complexities with case study on the optimized conditions toward coating process control

    Directory of Open Access Journals (Sweden)

    Ridha Djebali

    2015-09-01

    Full Text Available In the present study, we investigate a PSP using the Jets&Poudres soft. The plasma gas understanding is given to highlight the effects of gas mixtures proportions on diffusion parameters. An overview on the process complexities at main subsystems is given with focus on Argon plasma and optimal mixing; the powder acceleration and heat-up modeling are also presented. Under literature conditions and for He–Ar–H2 65–30–5% gas, it was found that the droplet's primary way is to coat. The used ternary mixture gives superior efficiency compared to the pure Argon which shows a prior way to rebound. Moreover, medium particles (dp≈45 µm present the high deposited rate among the splashed mass, a 100% molten ratio is observed for the small powder and only particles of size below 40.3 µm have evaporated, particles of initial diameter between 40.3 and 49 µm are fully molten and all particles above 71.9 µm are fully solid. The coat formed by the deposited mass will transfer a large amount of heat to the substrate (9–58 MW/m2. The crushed particle's rate is about 4% from the investigated number and the average fully molten particle's rate is about 72% and the rest of particles arrive in solid sate.

  8. Improving Single-Chamber Solid Oxide Fuel Cell Performance by Plasma Treatment Using an Atmospheric-Pressure Helium Plasma Jet

    Science.gov (United States)

    Kanazawa, Seiji; Iwao, Tadasuke; Akamine, Shuichi; Ichiki, Ryuta

    2011-08-01

    An atmospheric-pressure helium plasma jet was used for the surface treatment of the electrodes in single-chamber solid oxide fuel cells (SC-SOFCs). The jet-type plasma source used in this study is suitable for the continuous and fine-area processing of materials, such as patterned electrodes. The basic plasma property was investigated by optical emission spectroscopy. Improvement in the performance of SC-SOFC was observed for the plasma-treated cell. From the scanning electron microscopy (SEM) observation, it was found that the surface morphology of the cell was largely changed. The increase in the area of the three-phase boundary among the electrode, electrolyte, and gas phase promoted electrochemical reactions. Under single-chamber operation condition at 850 °C, an open circuit voltage of 650 mV and a maximum power density of approximately 75 mW/cm2 were achieved for a coplanar-type cell.

  9. Plasma-water interactions at atmospheric pressure in a dc microplasma

    Science.gov (United States)

    Patel, Jenish; Němcová, Lucie; Mitra, Somak; Graham, William; Maguire, Paul; Švrček, Vladimir; Mariotti, Davide

    2013-09-01

    Plasma-liquid interactions generate a variety of chemical species that are very useful for the treatment of many materials and that makes plasma-induced liquid chemistry (PiLC) very attractive for industrial applications. The understanding of plasma-induced chemistry with water can open up a vast range of plasma-activated chemistry in liquid with enormous potential for the synthesis of chemical compounds, nanomaterials synthesis and functionalization. However, this basic understanding of the chemistry occurring at the plasma-liquid interface is still poor. In the present study, different properties of water are analysed when processed by plasma at atmospheric-pressure with different conditions. In particular, pH, temperature and conductivity of water are measured against current and time of plasma processing. We also observed the formation of molecular oxygen (O2) and hydrogen peroxide (H2O2) for the same plasma conditions. The current of plasma processing was found to affect the water properties and the production of hydrogen peroxide in water. The relation between the number of electrons injected from plasma in water and the number of H2O2 molecules was established and based on these results a scenario of reactions channels activated by plasma-water interface is concluded.

  10. plasmatis Center for Innovation Competence: Controlling reactive component output of atmospheric pressure plasmas in plasma medicine

    Science.gov (United States)

    Reuter, Stephan

    2012-10-01

    The novel approach of using plasmas in order to alter the local chemistry of cells and cell environment presents a significant development in biomedical applications. The plasmatis center for innovation competence at the INP Greifswald e.V. performs fundamental research in plasma medicine in two interdisciplinary research groups. The aim of our plasma physics research group ``Extracellular Effects'' is (a) quantitative space and time resolved diagnostics and modelling of plasmas and liquids to determine distribution and composition of reactive species (b) to control the plasma and apply differing plasma source concepts in order to produce a tailored output of reactive components and design the chemical composition of the liquids/cellular environment and (c) to identify and understand the interaction mechanisms of plasmas with liquids and biological systems. Methods to characterize the plasma generated reactive species from plasma-, gas- and liquid phase and their biological effects will be presented. The diagnostic spectrum ranges from absorption/emission/laser spectroscopy and molecular beam mass spectrometry to electron paramagnetic resonance spectroscopy and cell biological diagnostic techniques. Concluding, a presentation will be given of the comprehensive approach to plasma medicine in Greifswald where the applied and clinical research of the Campus PlasmaMed association is combined with the fundamental research at plasmatis center.

  11. Simulation Tool for Dielectric Barrier Discharge Plasma Actuators at Atmospheric and Sub-Atmospheric Pressures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Traditional approaches for active flow separation control using dielectric barrier discharge (DBD) plasma actuators are limited to relatively low-speed flows and...

  12. Sheath and bulk expansion induced by RF bias in atmospheric pressure microwave plasma

    Science.gov (United States)

    Lee, Jimo; Nam, Woojin; Lee, Jae Koo; Yun, Gunsu

    2017-10-01

    A large axial volume expansion of microwave-driven plasma at atmospheric pressure is achieved by applying a low power radio frequency (RF) bias at an axial location well isolated from the original plasma bulk. The evolution of the plasma plume visualized by high speed ICCD imaging suggest that the free electrons drifting toward the bias electrode cause the prodigious expansion of the sheath, creating a stable plasma stream channel between the microwave and the RF electrodes. For argon plasma in ambient air, enhanced emissions of OH and N2 spectral lines are measured in the extended plume region, supporting the acceleration of electrons and subsequent generation of radical species. The coupling of RF bias with microwave provides an efficient way of enlarging the plasma volume and enhancing the production of radicals. Work supported by the National Research Foundation of Korea under BK21+ program and Grant No. 2015R1D1A1A01061556 (Ministry of Education).

  13. A battery-operated atmospheric-pressure plasma wand for biomedical applications

    Science.gov (United States)

    Pei, X.; Liu, J.; Xian, Y.; Lu, X.

    2014-04-01

    A handheld, battery-operated atmospheric-pressure plasma rod (named the plasma wand) which does not rely on an external power source (e.g. mains power or a power generator) or gas supply is reported. The plasma wand can be used for killing bacteria, fungi or viruses that are hidden in narrow channels such as the nasal cavity and ear canal, which are difficult to access using most currently available devices. Besides, the electrical characterization, plasma wand temperature, emission spectra of the plasma, ozone and OH radical concentration generated by the device, are investigated by different diagnostic methods. The ozone concentration reaches 120 ppm 1 mm away from the device and the OH concentration reaches 3.5 × 1014 cm-3 in the plasma. The preliminary bacteria inactivation experiment results show that all the bacteria samples on the microfiltration membrane are killed by this device within 30 s.

  14. Synthesis and texturization processes of (super)-hydrophobic fluorinated surfaces by atmospheric plasma

    CERN Document Server

    Hubert, Julie; Dufour, Thierry; Vandencasteele, Nicolas; Reniers, François; Viville, Pascal; Lazzaroni, Roberto; Raes, M; Terryn, Herman

    2016-01-01

    The synthesis and texturization processes of fluorinated surfaces by means of atmospheric plasma are investigated and presented through an integrated study of both the plasma phase and the resulting material surface. Three methods enhancing the surface hydrophobicity up to the production of super-hydrophobic surfaces are evaluated: (i) the modification of a polytetrafluoroethylene (PTFE) surface, (ii) the plasma deposition of fluorinated coatings and (iii) the incorporation of nanoparticles into those fluorinated films. In all the approaches, the nature of the plasma gas appears to be a crucial parameter for the desired property. Although a higher etching of the PTFE surface can be obtained with a pure helium plasma, the texturization can only be created if O2 is added to the plasma, which simultaneously decreases the total etching. The deposition of CxFy films by a dielectric barrier discharge leads to hydrophobic coatings with water contact angles (WCAs) of 115{\\textdegree}, but only the filamentary argon d...

  15. Electron dynamics and plasma jet formation in a helium atmospheric pressure dielectric barrier discharge jet

    Energy Technology Data Exchange (ETDEWEB)

    Algwari, Q. Th. [Centre for Plasma Physics, School of Maths and Physics, Queen' s University Belfast, University Road, Belfast, Northern Ireland BT7 1NN (United Kingdom); Electronic Department, College of Electronics Engineering, Mosul University, Mosul 41002 (Iraq); O' Connell, D. [Centre for Plasma Physics, School of Maths and Physics, Queen' s University Belfast, University Road, Belfast, Northern Ireland BT7 1NN (United Kingdom); York Plasma Institute, Department of Physics, University of York, York YO10 5DD (United Kingdom)

    2011-09-19

    The excitation dynamics within the main plasma production region and the plasma jets of a kHz atmospheric pressure dielectric barrier discharge (DBD) jet operated in helium was investigated. Within the dielectric tube, the plasma ignites as a streamer-type discharge. Plasma jets are emitted from both the powered and grounded electrode end; their dynamics are compared and contrasted. Ignition of these jets are quite different; the jet emitted from the powered electrode is ignited with a slight time delay to plasma ignition inside the dielectric tube, while breakdown of the jet at the grounded electrode end is from charging of the dielectric and is therefore dependent on plasma production and transport within the dielectric tube. Present streamer theories can explain these dynamics.

  16. Design and construction of triplet atmospheric cold plasma jet for sterilization

    Directory of Open Access Journals (Sweden)

    F. Sohbatzadeh

    2014-03-01

    Full Text Available In this paper, construction of triplet atmospheric plasma jet using argon, air, oxygen and nitrogen gases is reported. Bactericidal effect of the plasma jet is also investigated. To that end, longitudinal geometric configuration for the electrodes was chosen because it would increase the jet length. Electrical characteristics, jet length dependencies on the applied voltage and gas flow rate were decided, experimentally. Relative concentrations of chemical reactive species such as ozone, atomic oxygen, NOx compounds and hydroxyl were measured using optical emission spectroscopy. It was seen that atomic oxygen and ozone concentrations with triplet plasma jet are more than the concentration of single plasma jet. Triplet plasma jet was also used for sterilization of solid and liquid surfaces to disinfect gram-negative and gram-positive Escherichia coli and Streptococcus pyogenes bacteria. The results verified the effectiveness of the triplet plasma jet for killing bacteria.

  17. A novel method to design water spray cooling system to protect floating roof atmospheric storage tanks against fires

    Directory of Open Access Journals (Sweden)

    Iraj Alimohammadi

    2015-01-01

    Full Text Available Hydrocarbon bulk storage tank fires are not very common, but their protection is essential due to severe consequences of such fires. Water spray cooling system is one of the most effective ways to reduce damages to a tank from a fire. Many codes and standards set requirements and recommendations to maximize the efficiency of water spray cooling systems, but these are widely different and still various interpretations and methods are employed to design such systems. This article provides a brief introduction to some possible design methods of cooling systems for protection of storage tanks against external non-contacting fires and introduces a new method namely “Linear Density Method” and compares the results from this method to the “Average Method” which is currently in common practice. The average Method determines the flow rate for each spray nozzle by dividing the total water demand by the number of spray nozzles while the Linear Density Method determines the nozzle flow rate based on the actual flow over the surface to be protected. The configuration of the system includes a one million barrel crude oil floating roof tank to be protected and which is placed one half tank diameter from a similar adjacent tank with a full surface fire. Thermal radiation and hydraulics are modeled using DNV PHAST Version 6.53 and Sunrise PIPENET Version 1.5.0.2722 software respectively. Spray nozzles used in design are manufactured by Angus Fire and PNR Nozzles companies. Schedule 40 carbon steel pipe is used for piping. The results show that the cooling system using the Linear Density Method consumes 3.55% more water than the design using the average method assuming a uniform application rate of 4.1 liters per minute. Despite higher water consumption the design based on Linear Density Method alleviates the problems associated with the Average Method and provides better protection.

  18. Experience of high-nitrogenous steel powder application in repairs and surface hardening of responsible parts for power equipment by plasma spraying

    Science.gov (United States)

    Kolpakov, A. S.; Kardonina, N. I.

    2016-02-01

    The questions of the application of novel diffusion-alloying high-nitrogenous steel powders for repair and surface hardening of responsible parts of power equipment by plasma spraying are considered. The appropriateness of the method for operative repair of equipment and increasing its service life is justified. General data on the structure, properties, and manufacture of nitrogen-, aluminum-, and chromium-containing steel powders that are economically alloyed using diffusion are described. It is noted that the nitrogen release during the decomposition of iron nitrides, when heating, protects the powder particles from oxidation in the plasma jet. It is shown that the coating retains 50% of nitrogen that is contained in the powder. Plasma spraying modes for diffusion-alloying high-nitrogenous steel powders are given. The service properties of plasma coatings based on these powders are analyzed. It is shown that the high-nitrogenous steel powders to a nitrogen content of 8.9 wt % provide the necessary wear resistance and hardness of the coating and the strength of its adhesion to the substrate and corrosion resistance to typical aggressive media. It is noted that increasing the coating porosity promotes stress relaxation and increases its thickness being limited with respect to delamination conditions in comparison with dense coatings on retention of the low defectiveness of the interface and high adhesion to the substrate. The examples of the application of high-nitrogenous steel powders in power engineering during equipment repairs by service companies and overhaul subdivisions of heat power plants are given. It is noted that the plasma spraying of diffusion-alloyed high-nitrogenous steel powders is a unique opportunity to restore nitrided steel products.

  19. Comparative study between chemical and atmospheric pressure plasma jet cleaning on glass substrate

    Science.gov (United States)

    Elfa, Rizan Rizon; Ahmad, Mohd Khairul; Fhong, Soon Chin; Sahdan, Mohd Zainizan; Nayan, Nafarizal

    2017-01-01

    The atmospheric pressure plasma jet with low frequency and argon as working gas is presented in this paper to demonstrate its application for glass substrate clean and modification. The glass substrate clean by atmospheric pressure plasma jet is an efficient method to replace other substrate clean method. A comparative analysis is done in this paper between substrate cleaned by chemical and plasma treatment methods. Water contact angle reading is taken for a different method of substrate clean and period of treatment. Under the plasma treatment, the sample shows low surface adhesion due to having the surface property of super hydrophilic surface 7.26°. This comparative analysis is necessary in the industrial application for cost production due to sufficient time and method of substrate clean.

  20. Effect of atmospheric plasma treatment on seed germination of rice (Oryza sativa L.)

    Science.gov (United States)

    Penado, Keith Nealson M.; Mahinay, Christian Lorenz S.; Culaba, Ivan B.

    2018-01-01

    Multiple methods of improving plant development have been utilized over the past decades. Despite these improvements, there still exists a need for better planting methods due to the increasing population of a global community. Studies have reported that plasma treatment affects the growth and germination of a variety of plant species, including a multitude of grains which often takes the bulk in the diet of the average human being. This study explores the effect of atmospheric air plasma jet treatment on the seed germination of rice (Oryza sativa L.). The seeds were treated using an atmospheric air plasma jet for 1, 2, and 3 s. The effect of plasma exposure shows a reduction of trichomes on the surface of the seed. This caused a possible increase in wettability which significantly affected the seed germ length but did not affect the seed germination count after the germination period of 72 h.

  1. Residual stress determination in thermally sprayed metallic deposits by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Keller, Thomas; Margadant, Nikolaus; Pirling, Thilo; Riegert-Escribano, Maria J.; Wagner, Werner

    2004-05-25

    Neutron diffraction was used to obtain spatially resolved strain and stress profiles in thermally sprayed metallic 'NiCrAlY' deposits (chemical composition 67 wt.% Ni, 22 wt.% Cr, 10 wt.% Al, 1 wt.% Y) and the underlying steel substrates. Samples of four different spray techniques were analyzed: atmospheric and water stabilized plasma spraying (APS and WSP), flame spraying (FS) and wire arc spraying (WAS). The results are quantitatively compared with the average in-plane residual stress determined by complementary bending tests and the hole drilling technique. While the stress profiles from the surface to the interface in the deposits are similar for all investigated spray techniques, their absolute values and gradients vary strongly. This is attributed to different quenching stresses from the impinging particles, different thermal histories the deposit/substrate systems undergo during the spraying and subsequent cooling, and also to different coating properties. In the water stabilized plasma sprayed and the wire arc sprayed deposits, a gradient in the stress-free lattice parameter was observed. Crack formation is found to be a dominant mechanism for stress relaxation in the surface plane.

  2. Treatment of Candida albicans biofilms with low-temperature plasma induced by dielectric barrier discharge and atmospheric pressure plasma jet

    Science.gov (United States)

    Koban, Ina; Matthes, Rutger; Hübner, Nils-Olaf; Welk, Alexander; Meisel, Peter; Holtfreter, Birte; Sietmann, Rabea; Kindel, Eckhard; Weltmann, Klaus-Dieter; Kramer, Axel; Kocher, Thomas

    2010-07-01

    Because of some disadvantages of chemical disinfection in dental practice (especially denture cleaning), we investigated the effects of physical methods on Candida albicans biofilms. For this purpose, the antifungal efficacy of three different low-temperature plasma devices (an atmospheric pressure plasma jet and two different dielectric barrier discharges (DBDs)) on Candida albicans biofilms grown on titanium discs in vitro was investigated. As positive treatment controls, we used 0.1% chlorhexidine digluconate (CHX) and 0.6% sodium hypochlorite (NaOCl). The corresponding gas streams without plasma ignition served as negative treatment controls. The efficacy of the plasma treatment was determined evaluating the number of colony-forming units (CFU) recovered from titanium discs. The plasma treatment reduced the CFU significantly compared to chemical disinfectants. While 10 min CHX or NaOCl exposure led to a CFU log10 reduction factor of 1.5, the log10 reduction factor of DBD plasma was up to 5. In conclusion, the use of low-temperature plasma is a promising physical alternative to chemical antiseptics for dental practice.

  3. Treatment of Candida albicans biofilms with low-temperature plasma induced by dielectric barrier discharge and atmospheric pressure plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Koban, Ina; Welk, Alexander; Meisel, Peter; Holtfreter, Birte; Kocher, Thomas [Unit of Periodontology, Dental School, University of Greifswald, Rotgerberstr. 8, 17475 Greifswald (Germany); Matthes, Rutger; Huebner, Nils-Olaf; Kramer, Axel [Institute for Hygiene and Environmental Medicine, University of Greifswald, Walther-Rathenau-Str. 49 a, 17487 Greifswald (Germany); Sietmann, Rabea [Institute of Microbiology, University of Greifswald, Friedrich-Ludwig-Jahn-Str. 15, 17487 Greifswald (Germany); Kindel, Eckhard; Weltmann, Klaus-Dieter, E-mail: ina.koban@uni-greifswald.d [Leibniz Institute for Plasma Science and Technology (INP), Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany)

    2010-07-15

    Because of some disadvantages of chemical disinfection in dental practice (especially denture cleaning), we investigated the effects of physical methods on Candida albicans biofilms. For this purpose, the antifungal efficacy of three different low-temperature plasma devices (an atmospheric pressure plasma jet and two different dielectric barrier discharges (DBDs)) on Candida albicans biofilms grown on titanium discs in vitro was investigated. As positive treatment controls, we used 0.1% chlorhexidine digluconate (CHX) and 0.6% sodium hypochlorite (NaOCl). The corresponding gas streams without plasma ignition served as negative treatment controls. The efficacy of the plasma treatment was determined evaluating the number of colony-forming units (CFU) recovered from titanium discs. The plasma treatment reduced the CFU significantly compared to chemical disinfectants. While 10 min CHX or NaOCl exposure led to a CFU log{sub 10} reduction factor of 1.5, the log{sub 10} reduction factor of DBD plasma was up to 5. In conclusion, the use of low-temperature plasma is a promising physical alternative to chemical antiseptics for dental practice.

  4. Sterilization effect of atmospheric plasma on Escherichia coli and Bacillus subtilis endospores.

    Science.gov (United States)

    Hong, Y F; Kang, J G; Lee, H Y; Uhm, H S; Moon, E; Park, Y H

    2009-01-01

    Escherichia coli and Bacillus subtilis spores were treated with an atmospheric plasma mixture created by the ionization of helium and oxygen to investigate the inactivation efficiency of a low-temperature plasma below 70 degrees C. An electrical discharge plasma was produced at a radio frequency (RF) of 13.56 MHz, connected to a perforated circular electrode with a discharge spacing of 1-15 mm. The discharge gas was helium with 0-2% oxygen. For the plasma treatment, a dried E. coli cell or B. subtilis endospore suspension on a cover-glass was exposed to oxygen downstream of the plasma from holes in an RF-powered electrode. The sterilization effect of the RF plasma was highest with 0.2% oxygen, corresponding to the maximum production of oxygen radicals. Oxygen radicals generated by RF plasma are effective for the destruction of bacterial cells and endospores. Low-temperature atmospheric plasma can be used for the disinfection of diverse objects, especially for the inactivation of bacterial endospores.

  5. Separated Type Atmospheric Pressure Plasma Microjets Array for Maskless Microscale Etching

    Directory of Open Access Journals (Sweden)

    Yichuan Dai

    2017-06-01

    Full Text Available Maskless etching approaches such as microdischarges and atmospheric pressure plasma jets (APPJs have been studied recently. Nonetheless, a simple, long lifetime, and efficient maskless etching method is still a challenge. In this work, a separated type maskless etching system based on atmospheric pressure He/O2 plasma jet and microfabricated Micro Electro Mechanical Systems (MEMS nozzle have been developed with advantages of simple-structure, flexibility, and parallel processing capacity. The plasma was generated in the glass tube, forming the micron level plasma jet between the nozzle and the surface of polymer. The plasma microjet was capable of removing photoresist without masks since it contains oxygen reactive species verified by spectra measurement. The experimental results illustrated that different features of microholes etched by plasma microjet could be achieved by controlling the distance between the nozzle and the substrate, additive oxygen ratio, and etch time, the result of which is consistent with the analysis result of plasma spectra. In addition, a parallel etching process was also realized by plasma microjets array.

  6. Topographic, optical and chemical properties of zinc particle coatings deposited by means of atmospheric pressure plasma

    Science.gov (United States)

    Wallenhorst, L. M.; Loewenthal, L.; Avramidis, G.; Gerhard, C.; Militz, H.; Ohms, G.; Viöl, W.

    2017-07-01

    In this research, topographic, optical and chemical properties of zinc oxide layers deposited by a cold plasma-spray process were measured. Here, zinc micro particles were fed to the afterglow of a plasma spark discharge whereas the substrates were placed in a quite cold zone of the effluent plasma jet. In this vein, almost closed layers were realised on different samples. As ascertained by laser scanning and atomic force microscopic measurements the particle size of the basic layer is in the nanometre scale. Additionally, larger particles and agglomerates were found on its top. The results indicate a partial plasma-induced diminishment of the initial particles, most probably due to melting or vaporisation. It is further shown that the plasma gives rise to an increased oxidation of such particles as confirmed by X-ray photoelectron spectroscopy. Quantitative analysis of the resulting mixed layer was performed. It is shown that the deposited layers consist of zinc oxide and elemental zinc in approximately equal shares. In addition, the layer's band gap energy was determined by spectroscopic analysis. Here, considerable UV blocking properties of the deposited layers were observed. Possible underlying effects as well as potential applications are presented.

  7. Trajectory effect on the properties of large area ZnO thin films deposited by atmospheric pressure plasma jet

    Science.gov (United States)

    Juang, Jia-Yang; Chou, Tung-Sheng; Lin, Hsin-Tien; Chou, Yuan-Fang; Weng, Chih-Chiang

    2014-09-01

    Large area (117 mm × 185 mm) gallium-doped zinc oxide (GZO) films are prepared on glass substrates by atmospheric pressure plasma jet (APPJ) technique. The uniformity of material properties, in particular the electrical resistivity, of the deposited film is of great importance in reducing design complexity of the electron devices. We investigate the effects of scanning trajectory recipe (speed, pitch and number of passes) on structural and electrical properties of GZO thin films. We find that the trajectory has significant effects on the magnitude and uniformity of sheet resistance over the glass substrates. For single pass, the resistance appears higher at the starting part of spray, whereas, for cases of multiple passes, the highest resistance appears in the central part of the substrate. XRD, SEM, Hall measurement and residual stress are used to study the film properties and identify root causes of the nonuniform distribution of sheet resistance. We conclude that annealing time is the dominant root cause of the nonuniform resistance distribution, and other factors such as residual stress and structural characteristics may also have contributions.

  8. Design of a laboratory platform for atmospheric pressure biomedical plasma experiments

    Science.gov (United States)

    Lee, Sarah; Rutz, Sara; Hicks, Nathaniel; Briggs, Brandon

    2017-10-01

    The design of a laboratory set up for atmospheric pressure plasma (APP) experiments with biomedical applications is described. A comparison between various types of cold APP discharges (DC, RF, microwave) is presented, as well as various configurations of electrodes, dielectric materials, and gas feed conditions. Particular attention is paid to designs comprising floating electrode dielectric barrier discharges (FE-DBD) (for example as described in), but atmospheric pressure plasma jets are considered as well. A plan is discussed for initial experiments on the response of bacterial populations of E. coli and Deinococcus radiodurans to APP treatment as well as to media activated by APP. Supported by 2017 University of Alaska Anchorage Innovate Award.

  9. Oral bacterial inactivation using a novel low-temperature atmospheric-pressure plasma device

    Directory of Open Access Journals (Sweden)

    Ya-Ting Chang

    2016-03-01

    Conclusion: The novel low-temperature atmospheric-pressure device was capable of achieving effective sterilization of E. faecalis within a 2-minute interval. Further studies are needed to validate complete inactivation, refine the laboratory-made low-temperature plasma device, and develop a new plasma-jet device, which will be superior to traditional sterilization methods and can be used in root canal environment. This novel sterilization method can also be used as a clinical reference tool.

  10. Fundamental Studies of Transient, Atmospheric-Pressure, Small-Scale Plasmas

    Science.gov (United States)

    2017-01-23

    C. Jiang, R. Heller, J. Lane, and K. H. Schoenbach, " Ozone -free nitric oxide production using an atmospheric pressure surface discharge – a way to...Electrostatic modeling and energy-dependent studies showed that the direct and indirect electron-induced processes in the pulsed plasma jet are responsible for...Coupled sliding discharges : a scalable nonthermal plasma system utilizing positive and negative streamers on DISTRIBUTION A: Distribution

  11. Cleaning of niobium surface by plasma of diffuse discharge at atmospheric pressure

    Science.gov (United States)

    Tarasenko, V. F.; Erofeev, M. V.; Shulepov, M. A.; Ripenko, V. S.

    2017-07-01

    Elements composition of niobium surface before and after plasma treatment by runaway electron preionized diffuse discharge was investigated in atmospheric pressure nitrogen flow by means of an Auger electron spectroscopy. Surface characterizations obtained from Auger spectra show that plasma treatment by diffuse discharge after exposure of 120000 pulses provides ultrafine surface cleaning from carbon contamination. Moreover, the surface free energy of the treated specimens increased up to 3 times, that improve its adhesion property.

  12. Atmospheric pressure plasma polymerization of 1,3-butadiene for hydrophobic finishing of textile substrates

    Energy Technology Data Exchange (ETDEWEB)

    Samanta, Kartick K; Jassal, Manjeet; Agrawal, Ashwini K, E-mail: ashwini@smita-iitd.co, E-mail: manjeet.jassal@smita-iitd.co [Smart and Innovative Textile Materials Group (SMITA), Department of Textile Technology, Indian Institute of Technology, Hauz Khas, New Delhi-110016 (India)

    2010-02-01

    Atmospheric pressure plasma processing of textile has both ecological and economical advantages over the wet-chemical processing. However, reaction in atmospheric pressure plasma has important challenges to be overcome before it can be successfully used for finishing applications in textile. These challenges are (i) generating stable glow plasma in presence liquid/gaseous monomer, and (ii) keeping the generated radicals active in the presence of contaminants such as oxygen and air. In this study, a stable glow plasma was generated at atmospheric pressure in the mixture of gaseous reactive monomer-1,3-butadiene and He and was made to react with cellulosic textile substrate. After 12 min of plasma treatment, the hydrophilic surface of the cellulosic substrate turned into highly hydrophobic surface. The hydrophobic finish was found to be durable to soap washing. After soap washing, a water drop of 37 {mu}l took around 250 s to get absorbed in the treated sample compared to < 1 s in the untreated samples. The plasma modified samples showed water contact angle of around 134{sup 0}. Both top and bottom sides of the fabric showed similar hydrophobic results in terms of water absorbency and contact angle. The results may be attributed to chemical reaction of butadiene with the cellulosic textile substrate. The surface characterization of the plasma modified samples under SEM and AFM revealed modification of the surface under <100 nm. The results showed that atmospheric pressure plasma can be successfully used for carrying out reaction of 1,3-butadiene with cellulosic textile substrates for producing hydrophobic surface finish.

  13. Adhesion improvement of fibres by continuous plasma treatment at atmospheric pressure

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Løgstrup Andersen, Tom; Sørensen, Bent F.

    2013-01-01

    Carbon fibres and ultra-high-molecular-weight polyethylene (UHMWPE) fibres were continuously treated by a dielectric barrier discharge plasma at atmospheric pressure for adhesion improvement with epoxy resins. The plasma treatment improved wettability, increased the oxygen containing polar...... functional groups at the surface, and subsequently improved adhesion to the epoxy and fracture resistance of epoxy composites. Hansen solubility parameters (HSP), quantitatively describing physical interactions among molecules, were measured for the UHMWPE fibre surfaces. The result identifies two distinct...

  14. Degradation of polyethylene induced by plasma in oxidizing atmospheres; Degradacion de polietileno inducido por plasma en atmosferas oxidantes

    Energy Technology Data Exchange (ETDEWEB)

    Colin, E.; Olayo, M.G.; Cruz, G.J. [Facultad de Quimica, UAEM, Av. Tollocan y Colon, 50000 Toluca (Mexico)

    2002-07-01

    The garbage of polyethylene is not easily degradable in normal environmental conditions . The indiscriminate use of this polymer and the enormous quantity of garbage which is generated carries a damage to the environment due to its long life as waste. The objective of this work is to study the conditions in which can be carried out the degradation of polyethylene. A form of accelerating the degradation is exposing it to plasma with reactive atmospheres. In this work a study of surface modification of polyethylene by plasmas with discharges of direct current of oxygen and nitrogen is presented. (Author)

  15. Ultrafast laser-collision-induced fluorescence in atmospheric pressure plasma

    Science.gov (United States)

    Barnat, E. V.; Fierro, A.

    2017-04-01

    The implementation and demonstration of laser-collision-induced fluorescence (LCIF) generated in atmospheric pressure helium environments is presented in this communication. As collision times are observed to be fast (~10 ns), ultrashort pulse laser excitation (discharge conditions presented in this study (640 Torr He), the lower limit of electron density detection is ~1012 e cm-3. The spatial profiles of the 23S helium metastable and electrons are presented as functions of E/N to demonstrate the spatial resolving capabilities of the LCIF method.

  16. Laser surface treatment of plasma-sprayed yttria-stabilized zirconia coatings

    Directory of Open Access Journals (Sweden)

    Pinto, M. A.

    2005-12-01

    Full Text Available Un equipo láser continuo de CO2, con potencia nominal de 1 kW, se utilizó para sellar la superficie revestida con ZrO2 8 % Y2O3 por proyección por plasma sobre un substrato de acero AISI 1045. Se investigaron los efectos del tratamiento de fusión con láser sobre la microestrutura y la resistencia a la corrosión del recubrimiento. La resistencia a la corrosión se analizó por medidas electroquímicas en una solución de NaCl al 3 %. Las micrografias mostraron que la superficie del revestimiento presentó varias grietas pequeñas, sin embargo, no fueron observados poros. La microestructura de la capa sellada presentó una estructura en forma de columnas con crecimiento perpendicular a la superficie libre. El sellado a láser mejora la resistencia a la corrosión de los recubrimientos y aumenta la microdureza.

    Un equipo láser continuo de CO2, con potencia nominal de 1 kW, se utilizó para sellar la superficie revestida con ZrO2 8 % Y2O3 por proyección por plasma sobre un substrato de acero AISI 1045. Se investigaron los efectos del tratamiento de fusión con láser sobre la microestrutura y la resistencia a la corrosión del recubrimiento. La resistencia a la corrosión se analizó por medidas electroquímicas en una solución de NaCl al 3 %. Las micrografias mostraron que la superficie del revestimiento presentó varias grietas pequeñas, sin embargo, no fueron observados poros. La microestructura de la capa sellada presentó una estructura en forma de columnas con crecimiento perpendicular a la superficie libre. El sellado a láser mejora la resistencia a la corrosión de los recubrimientos y aumenta la microdureza.

  17. Effect of feed-gas humidity on nitrogen atmospheric-pressure plasma jet for biological applications.

    Science.gov (United States)

    Stephan, Karl D; McLean, Robert J C; DeLeon, Gian; Melnikov, Vadim

    2016-11-14

    We investigate the effect of feed-gas humidity on the oxidative properties of an atmospheric-pressure plasma jet using nitrogen gas. Plasma jets operating at atmospheric pressure are finding uses in medical and biological settings for sterilization and other applications involving oxidative stress applied to organisms. Most jets use noble gases, but some researchers use less expensive nitrogen gas. The feed-gas water content (humidity) has been found to influence the performance of noble-gas plasma jets, but has not yet been systematically investigated for jets using nitrogen gas. Low-humidity and high-humidity feed gases were used in a nitrogen plasma jet, and the oxidation effect of the jet was measured quantitatively using a chemical dosimeter known as FBX (ferrous sulfate-benzoic acid-xylenol orange). The plasma jet using high humidity was found to have about ten times the oxidation effect of the low-humidity jet, as measured by comparison with the addition of measured amounts of hydrogen peroxide to the FBX dosimeter. Atmospheric-pressure plasma jets using nitrogen as a feed gas have a greater oxidizing effect with a high level of humidity added to the feed gas.

  18. Electron density measurement of non-equilibrium atmospheric pressure plasma using dispersion interferometer

    Science.gov (United States)

    Yoshimura, Shinji; Kasahara, Hiroshi; Akiyama, Tsuyoshi

    2017-10-01

    Medical applications of non-equilibrium atmospheric plasmas have recently been attracting a great deal of attention, where many types of plasma sources have been developed to meet the purposes. For example, plasma-activated medium (PAM), which is now being studied for cancer treatment, has been produced by irradiating non-equilibrium atmospheric pressure plasma with ultrahigh electron density to a culture medium. Meanwhile, in order to measure electron density in magnetic confinement plasmas, a CO2 laser dispersion interferometer has been developed and installed on the Large Helical Device (LHD) at the National Institute for Fusion Science, Japan. The dispersion interferometer has advantages that the measurement is insensitive to mechanical vibrations and changes in neutral gas density. Taking advantage of these properties, we applied the dispersion interferometer to electron density diagnostics of atmospheric pressure plasmas produced by the NU-Global HUMAP-WSAP-50 device, which is used for producing PAM. This study was supported by the Grant of Joint Research by the National Institutes of Natural Sciences (NINS).

  19. Development of superhydrophobic surface on glass substrate by multi-step atmospheric pressure plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Han, Duksun [Department of Applied Plasma Engineering, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju, Jeollabuk-do 561-756 (Korea, Republic of); Moon, Se Youn, E-mail: symoon@jbnu.ac.kr [Department of Applied Plasma Engineering, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju, Jeollabuk-do 561-756 (Korea, Republic of); Department of Quantum system Engineering, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju, Jeollabuk-do 561-756 (Korea, Republic of)

    2015-07-31

    Superhydrophobic surface was prepared on a glass by helium based CH{sub 4} and C{sub 4}F{sub 8} atmospheric pressure plasmas, and its water wettability was investigated by a water droplet contact angle method. The water droplet spread over on the untreated glasses that showed the initial hydrophilic property of the glass surface. Then, the static contact angles became about 85° and 98° after a single step CH{sub 4} plasma treatment and a single step C{sub 4}F{sub 8} plasma treatment, respectively. The contact angle was remarkably increased to 152°, indicating a superhydrophobic property, after a sequential multi-step CH{sub 4} and C{sub 4}F{sub 8} plasma treatment. From the X-ray photoelectron spectroscopy and the field emission scanning electron microscope measurements, it was found that the physical morphologies and the chemical compositions were depending on the substrate materials, which were important factors for the superhydrophobicity. - Highlights: • Development of rapid and simple method for superhydrophobic surface • Effects of atmospheric pressure plasma for superhydrophobic surface preparation • Observation of chemical and physical surface modification by atmospheric pressure plasma • Effects of substrate properties for plasma–surface interaction.

  20. Effect of heater with plasma-sprayed mullite coatings on heating by far-infrared radiation. Mullite himaku wo keiseishita kanetsutai no ensekigaisen hosha tokusei oyobi kanetsu koka

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, M.; Nishino, A.; Suzuki, T. (Matsushita Electric Industrial Co. Ltd., Osaka (Japan))

    1993-09-30

    Effects of a quartz tube heater coated with plasma-sprayed mullite on the far-infrared radiation heating was investigated by means of spectral energy distribution in wavelength ranging from 1.4 to 14[mu]m, and color difference and weight loss observations before and after toasting of bread. Mullite material was sprayed on the opaque quartz tube substrate using an 80kW plasma-spray apparatus, to make a coating with thickness of 50[mu]m. The mullite coating on the quartz tube heater showed high far-infrared radiation. It was found that the mullite coating exhibited good wavelength change characteristics, and the spectral energy increased by about 7%. It was also illustrated that for the heating by the heater with mullite coating, the heating efficiency was improved during toasting of bread. As a result, the heater coated with mullite showed a decrease in heating time and also provided energy saving of around 12% during toasting of bread. 8 refs., 5 figs., 1 tab.

  1. Skeletal cell differentiation is enhanced by atmospheric dielectric barrier discharge plasma treatment.

    Directory of Open Access Journals (Sweden)

    Marla J Steinbeck

    Full Text Available Enhancing chondrogenic and osteogenic differentiation is of paramount importance in providing effective regenerative therapies and improving the rate of fracture healing. This study investigated the potential of non-thermal atmospheric dielectric barrier discharge plasma (NT-plasma to enhance chondrocyte and osteoblast proliferation and differentiation. Although the exact mechanism by which NT-plasma interacts with cells is undefined, it is known that during treatment the atmosphere is ionized generating extracellular reactive oxygen and nitrogen species (ROS and RNS and an electric field. Appropriate NT-plasma conditions were determined using lactate-dehydrogenase release, flow cytometric live/dead assay, flow cytometric cell cycle analysis, and Western blots to evaluate DNA damage and mitochondrial integrity. We observed that specific NT-plasma conditions were required to prevent cell death, and that loss of pre-osteoblastic cell viability was dependent on intracellular ROS and RNS production. To further investigate the involvement of intracellular ROS, fluorescent intracellular dyes Mitosox (superoxide and dihydrorhodamine (peroxide were used to assess onset and duration after NT-plasma treatment. Both intracellular superoxide and peroxide were found to increase immediately post NT-plasma treatment. These increases were sustained for one hour but returned to control levels by 24 hr. Using the same treatment conditions, osteogenic differentiation by NT-plasma was assessed and compared to peroxide or osteogenic media containing β-glycerolphosphate. Although both NT-plasma and peroxide induced differentiation-specific gene expression, neither was as effective as the osteogenic media. However, treatment of cells with NT-plasma after 24 hr in osteogenic or chondrogenic media significantly enhanced differentiation as compared to differentiation media alone. The results of this study show that NT-plasma can selectively initiate and amplify ROS

  2. Atmospheric air-plasma treatment of polyester fiber to improve the performance of nanoemulsion silicone

    Energy Technology Data Exchange (ETDEWEB)

    Parvinzadeh, Mazeyar, E-mail: mparvinzadeh@gmail.com [Department of Textile, Islamic Azad University, Shahre Rey Branch, Tehran (Iran, Islamic Republic of); Ebrahimi, Izadyar [Young Researchers Club, Islamic Azad University, Shahre Rey Branch, Tehran (Iran, Islamic Republic of)

    2011-02-15

    Influence of atmospheric air plasma treatment on performance of nanoemulsion silicone softener on polyethylene terephthalate fibers was investigated by the use of fourier transform infrared spectroscopy (FTIR), bending lengths (BL), wrinkle recovery angles (WRA), fiber friction coefficient analysis (FFCA), moisture absorbency (MA), scanning electron microscopy (SEM) and reflectance spectroscopy (RS). Results indicated that the plasma pretreatment modifies the surface of fibers and increases the reactivity of substrate toward nanoemulsion silicone. Moisture regain and microscopic tests showed that the combination of plasma and silicone treatments on polyethylene terephthalate can decrease moisture absorption due to uniform coating of silicone emulsion on surface of fibers.

  3. Atmospheric air-plasma treatment of polyester fiber to improve the performance of nanoemulsion silicone

    Science.gov (United States)

    Parvinzadeh, Mazeyar; Ebrahimi, Izadyar

    2011-02-01

    Influence of atmospheric air plasma treatment on performance of nanoemulsion silicone softener on polyethylene terephthalate fibers was investigated by the use of fourier transform infrared spectroscopy (FTIR), bending lengths (BL), wrinkle recovery angles (WRA), fiber friction coefficient analysis (FFCA), moisture absorbency (MA), scanning electron microscopy (SEM) and reflectance spectroscopy (RS). Results indicated that the plasma pretreatment modifies the surface of fibers and increases the reactivity of substrate toward nanoemulsion silicone. Moisture regain and microscopic tests showed that the combination of plasma and silicone treatments on polyethylene terephthalate can decrease moisture absorption due to uniform coating of silicone emulsion on surface of fibers.

  4. DNA damage in oral cancer cells induced by nitrogen atmospheric pressure plasma jets

    Energy Technology Data Exchange (ETDEWEB)

    Han, Xu; Ptasinska, Sylwia [Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Klas, Matej [Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Liu, Yueying [Harper Cancer Research Institute, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Sharon Stack, M. [Harper Cancer Research Institute, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

    2013-06-10

    The nitrogen atmospheric pressure plasma jet (APPJ) was applied to induce DNA damage of SCC-25 oral cancer cells. Optical emission spectra were taken to characterize the reactive species produced in APPJ. In order to explore the spatial distribution of plasma effects, cells were placed onto photo-etched grid slides and the antibody H2A.X was used to locate double strand breaks of DNA inside nuclei using an immunofluorescence assay. The number of cells with double strand breaks in DNA was observed to be varied due to the distance from the irradiation center and duration of plasma treatment.

  5. Atmospheric plasma generates oxygen atoms as oxidizing species in aqueous solutions

    Czech Academy of Sciences Publication Activity Database

    Hefny, M.M.; Pattyn, C.; Lukeš, Petr; Benedikt, J.

    2016-01-01

    Roč. 49, č. 40 (2016), s. 404002 ISSN 0022-3727 R&D Projects: GA MŠk(CZ) LD14080 Grant - others:European Cooperation in Science and Technology(XE) COST TD1208 Institutional support: RVO:61389021 Keywords : atmospheric pressure plasma * transport of reactive species * reactive oxygen species * aqueous phase chemistry * plasma and liquids * phenol aqueous chemistry Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.588, year: 2016 http://iopscience.iop.org/article/10.1088/0022-3727/49/40/404002

  6. Characterization of atmospheric pressure plasma treated wool/cashmere textiles: Treatment in nitrogen

    Science.gov (United States)

    Zanini, Stefano; Citterio, Attilio; Leonardi, Gabriella; Riccardi, Claudia

    2018-01-01

    We performed atmospheric pressure plasma treatments of wool/cashmere (15/85%) textiles with a dielectric barrier discharge (DBD) in nitrogen. The chemical properties of the plasma treated samples were investigated with attenuated total reflectance Fourier transform infrared (FTIR/ATR) spectroscopy, X-ray photoelectron microscopy (XPS), and fatty acid gas chromatographic analysis. Changes in mechanical properties and tactile performance of textiles after the plasma treatment were determined using the KES-F system. The analyses reveal significant surface modification of the treated fabrics, which enhances their surface wettability.

  7. Determination of Scattering and Absorption Coefficients for Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier Coatings at Elevated Temperatures

    Science.gov (United States)

    Eldridge, Jeffrey I.; Spuckler, Charles M.; Markham, James R.

    2009-01-01

    The temperature dependence of the scattering and absorption coefficients for a set of freestanding plasma-sprayed 8 wt% yttria-stabilized zirconia (8YSZ) thermal barrier coatings (TBCs) was determined at temperatures up to 1360 C in a wavelength range from 1.2 micrometers up to the 8YSZ absorption edge. The scattering and absorption coefficients were determined by fitting the directional-hemispherical reflectance and transmittance values calculated by a four-flux Kubelka Munk method to the experimentally measured hemispherical-directional reflectance and transmittance values obtained for five 8YSZ thicknesses. The scattering coefficient exhibited a continuous decrease with increasing wavelength and showed no significant temperature dependence. The scattering is primarily attributed to the relatively temperature-insensitive refractive index mismatch between the 8YSZ and its internal voids. The absorption coefficient was very low (less than 1 per centimeter) at wavelengths between 2 micrometers and the absorption edge and showed a definite temperature dependence that consisted of a shift of the absorption edge to shorter wavelengths and an increase in the weak absorption below the absorption edge with increasing temperature. The shift in the absorption edge with temperature is attributed to strongly temperature-dependent multiphonon absorption. While TBC hemispherical transmittance beyond the absorption edge can be predicted by a simple exponential decrease with thickness, below the absorption edge, typical TBC thicknesses are well below the thickness range where a simple exponential decrease in hemispherical transmittance with TBC thickness is expected. [Correction added after online publication August 11, 2009: "edge to a shorter wavelengths" has been updated as edge to shorter wavelengths."

  8. Effect of Suspension Plasma-Sprayed YSZ Columnar Microstructure and Bond Coat Surface Preparation on Thermal Barrier Coating Properties

    Science.gov (United States)

    Bernard, Benjamin; Quet, Aurélie; Bianchi, Luc; Schick, Vincent; Joulia, Aurélien; Malié, André; Rémy, Benjamin

    2017-08-01

    Suspension plasma spraying (SPS) is identified as promising for the enhancement of thermal barrier coating (TBC) systems used in gas turbines. Particularly, the emerging columnar microstructure enabled by the SPS process is likely to bring about an interesting TBC lifetime. At the same time, the SPS process opens the way to a decrease in thermal conductivity, one of the main issues for the next generation of gas turbines, compared to the state-of-the-art deposition technique, so-called electron beam physical vapor deposition (EB-PVD). In this paper, yttria-stabilized zirconia (YSZ) coatings presenting columnar structures, performed using both SPS and EB-PVD processes, were studied. Depending on the columnar microstructure readily adaptable in the SPS process, low thermal conductivities can be obtained. At 1100 °C, a decrease from 1.3 W m-1 K-1 for EB-PVD YSZ coatings to about 0.7 W m-1 K-1 for SPS coatings was shown. The higher content of porosity in the case of SPS coatings increases the thermal resistance through the thickness and decreases thermal conductivity. The lifetime of SPS YSZ coatings was studied by isothermal cyclic tests, showing equivalent or even higher performances compared to EB-PVD ones. Tests were performed using classical bond coats used for EB-PVD TBC coatings. Thermal cyclic fatigue performance of the best SPS coating reached 1000 cycles to failure on AM1 substrates with a β-(Ni,Pt)Al bond coat. Tests were also performed on AM1 substrates with a Pt-diffused γ-Ni/γ'-Ni3Al bond coat for which more than 2000 cycles to failure were observed for columnar SPS YSZ coatings. The high thermal compliance offered by both the columnar structure and the porosity allowed the reaching of a high lifetime, promising for a TBC application.

  9. Application of atmospheric pressure plasma on polyethylene for increased prosthesis adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Van Vrekhem, S., E-mail: stijn.vanvrekhem@ugent.be [Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of Engineering and Architecture, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Ghent (Belgium); Cools, P. [Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of Engineering and Architecture, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Ghent (Belgium); Declercq, H. [Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of Engineering and Architecture, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Ghent (Belgium); Tissue Engineering Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, De Pintelaan 185 6B3, 9000 Ghent (Belgium); Van Tongel, A. [Department of Orthopaedic Surgery and Traumatology, Ghent University Hospital, De Pintelaan 185 13K12, 9000 Ghent (Belgium); Vercruysse, C.; Cornelissen, M. [Tissue Engineering Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, De Pintelaan 185 6B3, 9000 Ghent (Belgium); De Geyter, N.; Morent, R. [Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of Engineering and Architecture, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Ghent (Belgium)

    2015-12-01

    Biopolymers are often subjected to surface modification in order to improve their surface characteristics. The goal of this study is to show the use of plasma technology to enhance the adhesion of ultra-high molecular weight polyethylene (UHMWPE) shoulder prostheses. Two different plasma techniques (low pressure plasma activation and atmospheric pressure plasma polymerization) are performed on UHMWPE to increase the adhesion between (1) the polymer and polymethylmethacrylate (PMMA) bone cement and (2) the polymer and osteoblast cells. Both techniques are performed using a dielectric barrier discharge (DBD). A previous paper showed that low pressure plasma activation of UHMWPE results in the incorporation of oxygen-containing functional groups, which leads to an increased surface wettability. Atmospheric pressure plasma polymerization of methylmethacrylate (MMA) on UHMWPE results in a PMMA-like coating, which could be deposited with a high degree of control of chemical composition and layer thickness. The thin film also proved to be relatively stable upon incubation in a phosphate buffer solution (PBS). This paper discusses the next stage of the study, which includes testing the adhesion of the plasma-activated and plasma-polymerized samples to bone cement through pull-out tests and testing the cell adhesion and proliferation on the samples. In order to perform the pull-out tests, all samples were cut to standard dimensions and fixed in bone cement in a reproducible way with a sample holder specially designed for this purpose. The cell adhesion and proliferation were tested by means of an MTS assay and live/dead staining after culturing MC3T3 osteoblast cells on UHMWPE samples. The results show that both plasma activation and plasma polymerization significantly improve the adhesion to bone cement and enhance cell adhesion and proliferation. In conclusion, it can be stated that the use of plasma technology can lead to an implant with improved quality and a subsequent

  10. Atmospheric pressure plasma jet's characterization and surface wettability driven by neon transformer

    Science.gov (United States)

    Elfa, R. R.; Nafarizal, N.; Ahmad, M. K.; Sahdan, M. Z.; Soon, C. F.

    2017-03-01

    Atmospheric pressure plasma driven by Neon transformer power supply argon is presented in this paper. Atmospheric pressure plasma system has attracted researcher interest over low pressure plasma as it provides a flexibility process, cost-efficient, portable device and vacuum-free device. Besides, another golden key of this system is the wide promising application in the field of work cover from industrial and engineering to medical. However, there are still numbers of fundamental investigation that are necessary such as device configuration, gas configuration and its effect. Dielectric barrier discharge which is also known as atmospheric pressure plasma discharge is created when there is gas ionization process occur which enhance the movement of atom and electron and provide energetic particles. These energetic particles can provide modification and cleaning property to the sample surface due to the bombardment of the high reactive ion and radicals to the sample surface. In order to develop atmospheric pressure plasma discharge, a high voltage and high frequency power supply is needed. In this work, we used a neon transformer power supply as the power supply. The flow of the Ar is feed into 10 mm cylinder quartz tube with different treatment time in order to investigate the effect of the plasma discharge. The analysis of each treatment time is presented by optical emission spectroscopy (OES) and water contact angle (WCA) measurement. The increase of gas treatment time shows increases intensity of reactive Ar and reduces the angle of water droplets in water contact angle. Treatment time of 20 s microslide glass surface shows that the plasma needle discharges have modified the sample surface from hydrophilic surface to superhydrophilic surface. Thus, this leads to another interesting application in reducing sample surface adhesion to optimize productivity in the industry of paintings, semiconductor and more.

  11. Cold Atmospheric Plasma Generated in Water and its Potential Use in Cancer Therapy

    CERN Document Server

    Chen, Zhitong; Lin, Li; Keidar, Michael

    2016-01-01

    Cold atmospheric plasma (CAP) has been emerged as a novel technology for cancer treatment. CAP can directly treat cells and tissue but such direct application is limited to skin or can be invoked as a supplement during open surgery. In this letter we report indirect plasma treatment using CAP produced in a water using three gases as carrier (argon, helium and nitrogen). Plasma stimulated water was applied to human breast cancer cell line (MDA-MB-231). MTT assays tests showed that using argon plasma had the strongest effect on inducing apoptosis in cultured human breast cancer cells. This result is attributed to the elevated production of the reactive oxygen species and reactive nitrogen species in water in the case of argon plasma.

  12. Pulse shaping of transversely excited atmospheric CO2 laser using a simple plasma shutter

    Science.gov (United States)

    Hurst, Noah; Harilal, S. S.

    2009-03-01

    The pulse from a transversely excited atmospheric CO2 laser consists of a sharp spike followed by a long, drawn out tail region spanning about 2-5 μs caused by the nitrogen gas in the laser cavity. The nitrogen tail is undesirable in many applications because it decreases the average power of the laser pulse. We employ a pinhole plasma shutter for eliminating the nitrogen tail and shortening the pulse width. The pinhole shutter optically triggers plasma at a certain point in time with respect to the temporal profile of the laser pulse. This way, a good portion of the sharp spike is transmitted, while the energy stored in the nitrogen tail is consumed in heating the plasma. This simplistic plasma shutter is easy to build and inexpensive compared to other existing plasma shutter designs.

  13. Fast low-temperature plasma reduction of monolayer graphene oxide at atmospheric pressure

    Science.gov (United States)

    Bodik, Michal; Zahoranova, Anna; Micusik, Matej; Bugarova, Nikola; Spitalsky, Zdenko; Omastova, Maria; Majkova, Eva; Jergel, Matej; Siffalovic, Peter

    2017-04-01

    We report on an ultrafast plasma-based graphene oxide reduction method superior to conventional vacuum thermal annealing and/or chemical reduction. The method is based on the effect of non-equilibrium atmospheric-pressure plasma generated by the diffuse coplanar surface barrier discharge in proximity of the graphene oxide layer. As the reduction time is in the order of seconds, the presented method is applicable to the large-scale production of reduced graphene oxide layers. The short reduction times are achieved by the high-volume power density of plasma, which is of the order of 100 W cm-3. Monolayers of graphene oxide on silicon substrate were prepared by a modified Langmuir-Schaefer method and the efficient and rapid reduction by methane and/or hydrogen plasma was demonstrated. The best results were obtained for the graphene oxide reduction in hydrogen plasma, as verified by x-ray photoelectron spectroscopy and Raman spectroscopy.

  14. Atmospheric Pressure Plasma: A High-Performance Tool for the Efficient Removal of Biofilms

    Science.gov (United States)

    Fricke, Katja; Koban, Ina; Tresp, Helena; Jablonowski, Lukasz; Schröder, Karsten; Kramer, Axel; Weltmann, Klaus-Dieter; von Woedtke, Thomas; Kocher, Thomas

    2012-01-01

    Introduction The medical use of non-thermal physical plasmas is intensively investigated for sterilization and surface modification of biomedical materials. A further promising application is the removal or etching of organic substances, e.g., biofilms, from surfaces, because remnants of biofilms after conventional cleaning procedures are capable to entertain inflammatory processes in the adjacent tissues. In general, contamination of surfaces by micro-organisms is a major source of problems in health care. Especially biofilms are the most common type of microbial growth in the human body and therefore, the complete removal of pathogens is mandatory for the prevention of inflammatory infiltrate. Physical plasmas offer a huge potential to inactivate micro-organisms and to remove organic materials through plasma-generated highly reactive agents. Method In this study a Candida albicans biofilm, formed on polystyrene (PS) wafers, as a prototypic biofilm was used to verify the etching capability of the atmospheric pressure plasma jet operating with two different process gases (argon and argon/oxygen mixture). The capability of plasma-assisted biofilm removal was assessed by microscopic imaging. Results The Candida albicans biofilm, with a thickness of 10 to 20 µm, was removed within 300 s plasma treatment when oxygen was added to the argon gas discharge, whereas argon plasma alone was practically not sufficient in biofilm removal. The impact of plasma etching on biofilms is localized due to the limited presence of reactive plasma species validated by optical emission spectroscopy. PMID:22880025

  15. Atmospheric pressure plasma: a high-performance tool for the efficient removal of biofilms.

    Directory of Open Access Journals (Sweden)

    Katja Fricke

    Full Text Available INTRODUCTION: The medical use of non-thermal physical plasmas is intensively investigated for sterilization and surface modification of biomedical materials. A further promising application is the removal or etching of organic substances, e.g., biofilms, from surfaces, because remnants of biofilms after conventional cleaning procedures are capable to entertain inflammatory processes in the adjacent tissues. In general, contamination of surfaces by micro-organisms is a major source of problems in health care. Especially biofilms are the most common type of microbial growth in the human body and therefore, the complete removal of pathogens is mandatory for the prevention of inflammatory infiltrate. Physical plasmas offer a huge potential to inactivate micro-organisms and to remove organic materials through plasma-generated highly reactive agents. METHOD: In this study a Candida albicans biofilm, formed on polystyrene (PS wafers, as a prototypic biofilm was used to verify the etching capability of the atmospheric pressure plasma jet operating with two different process gases (argon and argon/oxygen mixture. The capability of plasma-assisted biofilm removal was assessed by microscopic imaging. RESULTS: The Candida albicans biofilm, with a thickness of 10 to 20 µm, was removed within 300 s plasma treatment when oxygen was added to the argon gas discharge, whereas argon plasma alone was practically not sufficient in biofilm removal. The impact of plasma etching on biofilms is localized due to the limited presence of reactive plasma species validated by optical emission spectroscopy.

  16. Fourier transform infrared absorption spectroscopy characterization of gaseous atmospheric pressure plasmas with 2 mm spatial resolution

    Energy Technology Data Exchange (ETDEWEB)

    Laroche, G. [Laboratoire d' Ingenierie de Surface, Centre de Recherche sur les Materiaux Avances, Departement de genie des mines, de la metallurgie et des materiaux, Universite Laval, 1065, avenue de la Medecine, Quebec G1V 0A6 (Canada); Centre de recherche du CHUQ, Hopital St Francois d' Assise, 10, rue de l' Espinay, local E0-165, Quebec G1L 3L5 (Canada); Vallade, J. [Laboratoire Procedes, Materiaux et Energie Solaire, PROMES, CNRS, Technosud, Rambla de la Thermodynamique, F-66100 Perpignan (France); Agence de l' environnement et de la Ma Latin-Small-Letter-Dotless-I -carettrise de l' Energie, 20, avenue du Gresille, BP 90406, F-49004 Angers Cedex 01 (France); Bazinette, R.; Hernandez, E.; Hernandez, G.; Massines, F. [Laboratoire Procedes, Materiaux et Energie Solaire, PROMES, CNRS, Technosud, Rambla de la Thermodynamique, F-66100 Perpignan (France); Nijnatten, P. van [OMT Solutions bv, High Tech Campus 9, 5656AE Eindhoven (Netherlands)

    2012-10-15

    This paper describes an optical setup built to record Fourier transform infrared (FTIR) absorption spectra in an atmospheric pressure plasma with a spatial resolution of 2 mm. The overall system consisted of three basic parts: (1) optical components located within the FTIR sample compartment, making it possible to define the size of the infrared beam (2 mm Multiplication-Sign 2 mm over a path length of 50 mm) imaged at the site of the plasma by (2) an optical interface positioned between the spectrometer and the plasma reactor. Once through the plasma region, (3) a retro-reflector module, located behind the plasma reactor, redirected the infrared beam coincident to the incident path up to a 45 Degree-Sign beamsplitter to reflect the beam toward a narrow-band mercury-cadmium-telluride detector. The antireflective plasma-coating experiments performed with ammonia and silane demonstrated that it was possible to quantify 42 and 2 ppm of these species in argon, respectively. In the case of ammonia, this was approximately three times less than this gas concentration typically used in plasma coating experiments while the silane limit of quantification was 35 times lower. Moreover, 70% of the incoming infrared radiation was focused within a 2 mm width at the site of the plasma, in reasonable agreement with the expected spatial resolution. The possibility of reaching this spatial resolution thus enabled us to measure the gaseous precursor consumption as a function of their residence time in the plasma.

  17. Induction of proliferation of basal epidermal keratinocytes by cold atmospheric-pressure plasma.

    Science.gov (United States)

    Hasse, S; Duong Tran, T; Hahn, O; Kindler, S; Metelmann, H-R; von Woedtke, T; Masur, K

    2016-03-01

    Over the past few decades, new cold plasma sources have been developed that have the great advantage of operating at atmospheric pressure and at temperatures tolerable by biological material. New applications for these have emerged, especially in the field of dermatology. Recently it was demonstrated that cold atmospheric-pressure plasma positively influences healing of chronic wounds. The potential of cold plasma lies in its capacity to reduce bacterial load in the wound while at the same time stimulating skin cells and therefore promoting wound closure. In recent years, there have been great advances in the understanding of the molecular mechanisms triggered by cold plasma involving signalling pathways and gene regulation in cell culture. To investigate cold plasma-induced effects in ex vivo treated human skin biopsies. Human skin tissue was exposed to cold plasma for different lengths of time, and analysed by immunofluorescence with respect to DNA damage, apoptosis, proliferation and differentiation markers. After cold plasma treatment, the epidermal integrity and keratin expression pattern remained unchanged. As expected, the results revealed an increase in apoptotic cells after 3 and 5 min of treatment. Strikingly, an induction of proliferating basal keratinocytes was detected after cold plasma exposure for 1 and 3 min. As these are the cells that regenerate the epidermis, this could indeed be beneficial for wound closure. We investigated the effect of cold plasma on human skin by detecting molecules for growth and apoptosis, and found that both processes are dependent on treatment time. Therefore, this approach offers promising results for further applications of cold plasma in clinical dermatology. © 2015 British Association of Dermatologists.

  18. Plasma action on helium flow in cold atmospheric pressure plasma jet experiments

    Science.gov (United States)

    Darny, T.; Pouvesle, J.-M.; Fontane, J.; Joly, L.; Dozias, S.; Robert, E.

    2017-10-01

    In this work, helium flow modifications, visualized by schlieren imaging, induced by the plasma generated in a plasma jet have been studied in conditions used for biomedical treatments (jet being directed downwards with a low helium flow rate). It has been shown that the plasma action can shift up to few centimeters downstream the effects of buoyancy, which allows to the helium flow to reach a target below in conditions for which it is not the case when the plasma is off. This study reveals the critical role of large and long lifetime negative ions during repetitive operations in the kHz regime, inducing strong modifications in the gas propagation. The cumulative added streamwise momentum transferred to ambient air surrounding molecules resulting from a series of applied voltage pulses induces a gradual built up of a helium channel on tens of millisecond timescale. In some conditions, a remarkable stable cylindrical helium channel can be generated to the target with plasma supplied by negative polarity voltage pulses whereas a disturbed flow results from positive polarity operation. This has a direct effect on air penetration in the helium channel and then on the reactive species production over the target which is of great importance for biomedical applications. It has also been shown that with an appropriate combination of negative and positive polarity pulses, it is possible to benefit from both polarity features in order to optimize the plasma plume propagation and plasma delivery to a target.

  19. Surface modification of several dental substrates by non-thermal, atmospheric plasma brush

    Science.gov (United States)

    Chen, Mingsheng; Zhang, Ying; Driver, M. Sky; Caruso, Anthony N.; Yu, Qingsong; Wang, Yong

    2013-01-01

    Objective The purpose of this study was to reveal the effectiveness of non-thermal atmospheric plasma brush in surface wettability and modification of four dental substrates. Methods Specimens of dental substrates including dentin, enamel, and two composites Filtek Z250, Filtek LS Silorane were prepared (~2 mm thick, ~10 mm diameter). The prepared surfaces were treated for 5–45 s with a non-thermal atmospheric plasma brush working at temperatures from 36 to 38 °C. The plasma-treatment effects on these surfaces were studied with contact-angle measurement, X-ray photoemission spectroscopy (XPS) and scanning electron microscopy (SEM). Results The non-thermal atmospheric argon plasma brush was very efficient in improving the surface hydrophilicity of four substrates studied. The results indicated that water contact angle values decreased considerably after only 5 s plasma treatment of all these substrates. After 30 s treatment, the values were further reduced to <5°, which was close to a value for super hydrophilic surfaces. XPS analysis indicated that the percent of elements associated with mineral in dentin/enamel or fillers in the composites increased. In addition, the percent of carbon (%C) decreased while %O increased for all four substrates. As a result, the O/C ratio increased dramatically, suggesting that new oxygen-containing polar moieties were formed on the surfaces after plasma treatment. SEM surface images indicated that no significant morphology change was induced on these dental substrates after exposure to plasmas. Significance Without affecting the bulk properties, a super-hydrophilic surface could be easily achieved by the plasma brush treatment regardless of original hydrophilicity/hydrophobicity of dental substrates tested. PMID:23755823

  20. Sterilization of packed matter by means of low temperature atmospheric pressure plasmas

    DEFF Research Database (Denmark)

    Leipold, Frank

    2010-01-01

    Summary form only given. The decontamination of material in closed containers by means of atmospheric pressure plasmas is investigated. The target is Listeria monocytogenes, a bacterium which causes listeriosis and can be found in plants and food. The non-pathogenic species, Listeria innocua, is ...

  1. Controlling Brochothrix thermosphacta as a spoilage risk using in-package atmospheric cold plasma.

    Science.gov (United States)

    Patange, Apurva; Boehm, Daniela; Bueno-Ferrer, Carmen; Cullen, P J; Bourke, Paula

    2017-09-01

    Brochothrix thermosphacta is the predominant spoilage microorganism in meat and its control in processing environments is important to maintain meat product quality. Atmospheric cold plasma is of interest for control of pathogenic and spoilage microorganisms in foods. This study ascertained the potential of dielectric barrier discharge atmospheric cold plasma (DBD-ACP) for control of B. thermosphacta, taking microbial and food environment factors into consideration, and investigated the shelf-life of lamb chop after in-package plasma treatment in modified atmosphere. Community profiling was used to assess the treatment effects on the lamb microflora. ACP treatment (80 kV) for 30s inactivated B. thermosphacta populations below detection levels in PBS, while 5 min treatment achieved a 2 Log cycle reduction using a complex meat model medium and attached cells. The antimicrobial efficacy of plasma was reduced but still apparent on lamb chop surface-inoculated with high concentrations of B. thermosphacta. Lamb chop treated under modified atmosphere exhibited reduced microbial growth over the product shelf-life and community profiling showed no evident changes to the microbial populations after the treatment. The overall results indicated potential of ACP to enhance microbial control leading to meat storage life extension through adjusting the modality of treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Diffuse plasma treatment of polyamide 66 fabric in atmospheric pressure air

    Energy Technology Data Exchange (ETDEWEB)

    Li, Lee, E-mail: leeli@mail.hust.edu.cn; Peng, Ming-yang; Teng, Yun; Gao, Guozhen

    2016-01-30

    Graphical abstract: - Highlights: • A cylindrical-electrode nanosecond-pulse diffuse-discharge reactor is presented. • Large-scale non-thermal plasmas were generated steadily in atmospheric air. • Treated PA66 fabric is etched with oxygen-containing group increases. • The hydrophily of treated PA66 fabric improves effectively. • Extending the treatment time is a method to reduce the treatment frequency. - Abstract: The polyamide 66 (PA66) fabrics are hard to be colored or glued in industrial production due to the poor hydrophily. Diffuse plasma is a kind of non-thermal plasma generated at atmospheric pressure in air. This paper proposes that large-scale diffuse plasma generated between wire electrodes can be employed for improving the hydrophily of PA66 fabrics. A repetitive nanosecond-pulse diffuse-discharge reactor using a cylindrical wire electrode configuration is presented, which can generate large-scale non-thermal plasmas steadily at atmospheric pressure without any barrier dielectric. Then the reactor is used to treat PA66 fabrics in different discharge conditions. The hydrophilicity property of modified PA66 is measured by wicking test method. The modified PA66 is also analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) to prove the surface changes in physical microstructure and chemical functional groups, respectively. What's more, the effects of treatment time and treatment frequency on surface modification are investigated and discussed.

  3. Simulation Tool for Dielectric Barrier Discharge Plasma Actuators at Atmospheric and Sub-Atmospheric Pressures: SBIR Phase I Final Report

    Science.gov (United States)

    Likhanskii, Alexandre

    2012-01-01

    This report is the final report of a SBIR Phase I project. It is identical to the final report submitted, after some proprietary information of administrative nature has been removed. The development of a numerical simulation tool for dielectric barrier discharge (DBD) plasma actuator is reported. The objectives of the project were to analyze and predict DBD operation at wide range of ambient gas pressures. It overcomes the limitations of traditional DBD codes which are limited to low-speed applications and have weak prediction capabilities. The software tool allows DBD actuator analysis and prediction for subsonic to hypersonic flow regime. The simulation tool is based on the VORPAL code developed by Tech-X Corporation. VORPAL's capability of modeling DBD plasma actuator at low pressures (0.1 to 10 torr) using kinetic plasma modeling approach, and at moderate to atmospheric pressures (1 to 10 atm) using hydrodynamic plasma modeling approach, were demonstrated. In addition, results of experiments with pulsed+bias DBD configuration that were performed for validation purposes are reported.

  4. Evaluation of Surface Cleaning Procedures in Terms of Gas Sensing Properties of Spray-Deposited CNT Film: Thermal- and O2 Plasma Treatments

    Directory of Open Access Journals (Sweden)

    Joon Hyub Kim

    2016-12-01

    Full Text Available The effect of cleaning the surface of single-walled carbon nanotube (SWNT networks by thermal and the O2 plasma treatments is presented in terms of NH3 gas sensing characteristics. The goal of this work is to determine the relationship between the physicochemical properties of the cleaned surface (including the chemical composition, crystal structure, hydrophilicity, and impurity content and the sensitivity of the SWNT network films to NH3 gas. The SWNT networks are spray-deposited on pre-patterned Pt electrodes, and are further functionalized by heating on a programmable hot plate or by O2 plasma treatment in a laboratory-prepared plasma chamber. Cyclic voltammetry was employed to semi-quantitatively evaluate each surface state of various plasma-treated SWNT-based electrodes. The results show that O2 plasma treatment can more effectively modify the SWNT network surface than thermal cleaning, and can provide a better conductive network surface due to the larger number of carbonyl/carboxyl groups, enabling a faster electron transfer rate, even though both the thermal cleaning and the O2 plasma cleaning methods can eliminate the organic solvent residues from the network surface. The NH3 sensors based on the O2 plasma-treated SWNT network exhibit higher sensitivity, shorter response time, and better recovery of the initial resistance than those prepared employing the thermally-cleaned SWNT networks.

  5. Atmospheric pressure plasma jets: an overview of devices and new directions

    Science.gov (United States)

    Winter, J.; Brandenburg, R.; Weltmann, K.-D.

    2015-12-01

    Atmospheric pressure plasma jets have a long history of more than 50 years. During this time their design and plasma generation mechanism has been developed and adapted to various fields of applications. This review aims at giving an overview of jet devices by starting with a brief history of their development. This is followed by an overview of commonly used terms and definitions as well as a survey of different classification schemes (e.g. geometry, excition frequency or specific energy input) described in literature. A selective update of new designs and novel research achievments on atmospheric pressure plasma jets published in 2012 or later shows the impressive variety and rapid development of the field. Finally, a brief outlook on the future trends and directions is given.

  6. How to Ignite an Atmospheric Pressure Microwave Plasma Torch without Any Additional Igniters

    Science.gov (United States)

    Leins, Martina; Gaiser, Sandra; Schulz, Andreas; Walker, Matthias; Schumacher, Uwe; Hirth, Thomas

    2015-01-01

    This movie shows how an atmospheric pressure plasma torch can be ignited by microwave power with no additional igniters. After ignition of the plasma, a stable and continuous operation of the plasma is possible and the plasma torch can be used for many different applications. On one hand, the hot (3,600 K gas temperature) plasma can be used for chemical processes and on the other hand the cold afterglow (temperatures down to almost RT) can be applied for surface processes. For example chemical syntheses are interesting volume processes. Here the microwave plasma torch can be used for the decomposition of waste gases which are harmful and contribute to the global warming but are needed as etching gases in growing industry sectors like the semiconductor branch. Another application is the dissociation of CO2. Surplus electrical energy from renewable energy sources can be used to dissociate CO2 to CO and O2. The CO can be further processed to gaseous or liquid higher hydrocarbons thereby providing chemical storage of the energy, synthetic fuels or platform chemicals for the chemical industry. Applications of the afterglow of the plasma torch are the treatment of surfaces to increase the adhesion of lacquer, glue or paint, and the sterilization or decontamination of different kind of surfaces. The movie will explain how to ignite the plasma solely by microwave power without any additional igniters, e.g., electric sparks. The microwave plasma torch is based on a combination of two resonators — a coaxial one which provides the ignition of the plasma and a cylindrical one which guarantees a continuous and stable operation of the plasma after ignition. The plasma can be operated in a long microwave transparent tube for volume processes or shaped by orifices for surface treatment purposes. PMID:25938699

  7. Plasma Beta Stratification in the Solar Atmosphere: A Possible Explanation for the Penumbra Formation

    Science.gov (United States)

    Bourdin, Ph.-A.

    2017-12-01

    Plasma beta is an important and fundamental physical quantity in order to understand plasma dynamics, particularly in the context of magnetically active stars, because it tells about the domination of magnetic versus thermodynamic processes on the plasma motion. We estimate the value ranges of plasma beta in different regions within the solar atmosphere and we describe a possible mechanism that helps forming a penumbra. For that we evaluate data from a 3D magnetohydrodynamic model of the solar corona above a magnetically active region. We compare our results with previously established data that is based on magnetic field extrapolations and that was matched for some observations. Our model data suggest that plasma beta in the photosphere should be considered to be larger than unity outside of sunspots. However, in the corona we also find that the beta value range reaches lower than previously thought, which coincides with a recent observation. We present an idea based on a gravity-driven process in a high-beta regime that might be responsible for the formation of the penumbra around sunspot umbra, where the vertical field strength reaches a given threshold. This process would also explain counter-Evershed flows. Regarding the thermal and magnetic pressure within the mixed-polarity solar atmosphere, including non-vertical magnetic field and quiet regions, plasma beta may reach unity at practically any height from the photosphere to the outer corona.

  8. Effects of atmospheric pressure plasma jet with floating electrode on murine melanoma and fibroblast cells

    Science.gov (United States)

    Xu, G.; Liu, J.; Yao, C.; Chen, S.; Lin, F.; Li, P.; Shi, X.; Zhang, Guan-Jun

    2017-08-01

    Atmospheric pressure cold plasma jets have been recently shown as a highly promising tool in certain cancer therapies. In this paper, an atmospheric pressure plasma jet (APPJ) with a one inner floating and two outer electrode configuration using helium gas for medical applications is developed. Subjected to a range of applied voltages with a frequency of 19.8 kHz at a fixed rate of gas flow (i.e., 3 l/min), electrical and optical characteristics of the APPJ are investigated. Compared with the device only with two outer electrodes, higher discharge current, longer jet, and more active species in the plasma plume at the same applied voltage together with the lower gas breakdown voltage can be achieved through embedding a floating inner electrode. Employing the APPJ with a floating electrode, the effects of identical plasma treatment time durations on murine melanoma cancer and normal fibroblast cells cultured in vitro are evaluated. The results of cell viability, cell apoptosis, and DNA damage detection show that the plasma can inactivate melanoma cells in a time-dependent manner from 10 s to 60 s compared with the control group (p melanoma cells at the same treatment time. The different basal reactive oxygen species level and antioxidant superoxide dismutase level of two kinds of cells may account for their different responses towards the identical plasma exposure.

  9. Sterilization by negative and positive DC plasma with a micro discharge gap at atmospheric pressure

    Science.gov (United States)

    Li, Hua; Jiang, Lin-Xiu; Jiang, Yong-Rong; Zhu, Jian-Min; Chen, Zhen-Cheng

    2017-11-01

    A new needle-to-droplet electrode structure with a micro discharge gap (2 mm) was designed to achieve direct current (DC) discharge plasma in ambient air with the aim of using the plasma to sterilize liquids. Without using noble gases or an external air flow, we succeeded in generating both a negative and positive DC plasma at atmospheric pressure. The plasma was driven by a 0 to ‑20,000 V, 100 W DC power supply. A stainless steel needle with a tip diameter of ˜ 50μm and a 200-μL droplet of bacteria-containing liquid served as the electrodes. At atmospheric pressure and room temperature (23∘C), utilizing the negative DC plasma, the discharge time lasted 10 s; the results showed that the higher the discharge voltage, the more efficient the sterilization effect. Conversely, when we applied a voltage of ‑5.5 kV, we found that the sterilization effect was more efficient for longer discharge times. Our findings demonstrate that Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) can be killed in about 30 s. Our experiments show that our sterilization method required less time and was more efficient for positive than for negative DC plasma under the same conditions.

  10. Sterilization of soybean powder with plasma treatment in atmospheric humid air

    Science.gov (United States)

    Iwami, R.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.; Nakayama, A.; Nakagawa, K.

    2013-10-01

    Sterilization of foods has been performed by conventional methods such as heat, steam and chemical solutions. However, these sterilization techniques could cause damages to the food material. It is considered that plasma sterilization at atmospheric pressure is one of the promising alternative methods because of the low temperature process. In our previous study, the inactivation of Bacillus atrophaeusspores by a dielectric barrier discharge (DBD) plasma produced in atmospheric humid air was investigated in order to develop low-temperature, low-cost and high-speed plasma sterilization technique. The results showed that the inactivation of Bacillus atrophaeusspores was found to be dependent strongly on the humidity. In the present study, the plasma treatment technique in humid air is applied to sterilization of soybean powder. Effects of plasma sterilization were successfully confirmed by a colony counting method. It was found that the sterilization efficiency was increased by using the humid air as the discharge gas. In the conference, an improvement of the plasma treatment system to enhance the sterilization efficiency will be shown.

  11. Effect of atmospheric pressure plasma treatment condition on adhesion of ramie fibers to polypropylene for composite

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ying [College of Material and Textile Engineering, Jiaxing University, Jiaxing 314033 (China); Center for Plasma-Aided Manufacturing, Madison, WI 53706 (United States); School of Human Ecology, University of Wisconsin-Madison, Madison, WI 53706 (United States); Manolache, Sorin [Center for Plasma-Aided Manufacturing, Madison, WI 53706 (United States); US Forest Products Laboratory, Madison, WI 53726 (United States); Qiu, Yiping, E-mail: ypqiu@dhu.edu.cn [College of Textiles, Donghua University, Shanghai 201620 (China); Sarmadi, Majid, E-mail: majidsar@wisc.edu [Center for Plasma-Aided Manufacturing, Madison, WI 53706 (United States); School of Human Ecology, University of Wisconsin-Madison, Madison, WI 53706 (United States); Materials Science Program, University of Wisconsin-Madison, Madison, WI 53706 (United States)

    2016-02-28

    Graphical abstract: - Highlights: • The continuous ethanol flow technique can successfully modify ramie fiber surface with an increase in IFSS value up to 50%. • Response surface methodology was applied to design the plasma treatment parameters for ramie fiber modification. • The ethanol flow rate was the most influential treatment parameter in plasma modification process. - Abstract: In order to improve the interfacial adhesion between hydrophilic ramie fibers and hydrophobic polypropylene (PP) matrices, ramie fibers are modified by atmospheric pressure dielectric barrier discharge (DBD) plasma with our continuous ethanol flow technique in helium environment. A central composite design of experiments with different plasma processing parameter combinations (treatment current, treatment time and ethanol flow rate) is applied to find the most influential parameter and to obtain the best modification effect. Field emission scanning electron microscope (SEM) shows the roughened surfaces of ramie fibers from the treated groups due to plasma etching effect. Dynamic contact angle analysis (DCAA) demonstrates that the wettability of the treated fibers drastically decreases. Microbond pullout test shows that the interfacial shear strength (IFSS) between treated ramie fibers and PP matrices increases significantly. Residual gas analysis (RGA) confirms the creation of ethyl groups during plasma treatment. This study shows that our continuous ethanol flow technique is effective in the plasma modification process, during which the ethanol flow rate is the most influential parameter but all parameters have simultaneous influence on plasma modification effect of ramie fibers.

  12. Disinfection of Streptococcus mutans biofilm by a non-thermal atmospheric plasma brush

    Science.gov (United States)

    Hong, Qing; Dong, Xiaoqing; Chen, Meng; Xu, Yuanxi; Sun, Hongmin; Hong, Liang; Wang, Yong; Yu, Qingsong

    2016-07-01

    This study investigated the argon plasma treatment effect on disinfecting dental biofilm by using an atmospheric pressure plasma brush. Streptococcus mutans biofilms were developed for 3 days on the surfaces of hydroxyapatite (HA) discs, which were used to simulate human tooth enamel. After plasma treatment, cell viability in the S. mutans biofilms was characterized by using 3-(4,5-dimethylazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and confocal laser scanning microscopy (CLSM). Compared with the untreated control group, about 90% bacterial reduction in the biofilms was observed after 1 min plasma treatment. Scanning electron microscopy (SEM) examination indicated severe cell damages occurred on the top surface of the plasma treated biofilms. Confocal laser scanning microscopy (CLSM) showed that plasma treatment was effective as deep as 20 µm into the biofilms. When combined with antibiotic treatment using 0.2% chlorhexidine digluconate solution, the plasma treatment became more effective and over 96% bacterial reduction was observed with 1 min plasma treatment.

  13. DEVELOPMENT OF WEAR RESISTANT COATINGS FORMED BY PLASMA SPRAYING OF ALLOY Ni–Fe–Cr–Si–B–C SYSTEM REINFORCED WITH CERAMICS Al2O3

    Directory of Open Access Journals (Sweden)

    A. S. Kalinichenko

    2016-01-01

    Full Text Available . Creating a functionally oriented, including nanostructured, anti-friction materials and coatings with qualitatively new complex of service properties is an important scientific and practical problem. In particular, for the cable industry it is urgent task of ensuring the high performance properties of fast deteriorating stretching and supporting rollers. Working surfaces of these parts operate under practically dry friction conditions with constantly updated material of stretching wire. Plasma spraying is one of the widely used methods of surface engineering to create wear resistant coatings and which is characterized with process flexibility and the ability to create coatings using various materials and alloys including composite ones. The installation UPU-3D with the PP-25 plasma torch was used for plasma spraying. The thickness of the sprayed layer was 0.8–1.1 mm. As a material for the deposition of composite coatings a powder mixture of self-fluxing nickel alloy PG-HN80SR4 (system Ni–Fe–Cr–Si–B–C and a neutral oxide ceramics Al2O3 was used. The amount of ceramics varied from 15 to 33 %. This ceramic oxide was selected due to the desire to reduce coatings’ costs while providing high durability. Carried out phase and microstructural studies have shown when ceramics was added in an amount more than 20 % a formation of conglomerates formed by not melted alumina particles often was observed. These conglomerates serve as crack formation centers in the coating. The phase composition of the coatings practically does not depend on the content of ceramics compounds. Tribological tests have shown that the best results were obtained when the content of the oxide ceramic in the coating was in the range from 15 to 20 %.

  14. Microstructure and Wear Behavior of FeCoCrNiMo0.2 High Entropy Coatings Prepared by Air Plasma Spray and the High Velocity Oxy-Fuel Spray Processes

    Directory of Open Access Journals (Sweden)

    Tianchen Li

    2017-09-01

    Full Text Available In the present research, the spherical FeCoCrNiMo0.2 high entropy alloy (HEA powders with a single FCC solid solution structure were prepared by gas atomization. Subsequently, the FeCoCrNiMo0.2 coatings with a different content of oxide inclusions were prepared by air plasma spraying (APS and high-velocity oxy-fuel spraying (HVOF, respectively. The microstructure, phase composition, mechanical properties, and tribological behaviors of these HEA coatings were investigated. The results showed that both HEA coatings showed a typical lamellar structure with low porosity. Besides the primary FCC phase, a mixture of Fe2O3, Fe3O4, and AB2O4 (A = Fe, Co, Ni, and B = Fe, Cr was identified as the oxide inclusions. The oxide content of the APS coating and HVOF coating was calculated to be 47.0% and 12.7%, respectively. The wear resistance of the APS coating was approximately one order of magnitude higher than that of the HVOF coating. It was mainly attributed to the self-lubricated effect caused by the oxide films. The mass loss of the APS coating was mainly ascribed to the breakaway of the oxide film, while the main wear mechanism of the HVOF coating was the abrasive wear.

  15. Effect of Al2O3 Reinforcement and Al2O3–13 wt% TiO2 Bond Coat on Plasma Sprayed Hydroxyapatite Coating

    OpenAIRE

    Manoj Mittal; Nath, S K; Satya Prakash

    2012-01-01

    In present work an attempt has been made to enhance mechanical properties of plasma sprayed hydroxyapatite coating by addition of 10 wt% aluminum oxide. A bond coat of Al2O3-13TiO2 has been  applied to improve strength of hydroxyapatite composite coating. Mechanical properties of coatings with addition of alumina and with incorporation of bond coat have been investigated in accordance with the ASTM C 633-79. Results indicate that the tensile bond strength of hydroxyapatite coating increased b...

  16. Characterizations of atmospheric pressure low temperature plasma jets and their applications

    Science.gov (United States)

    Karakas, Erdinc

    2011-12-01

    Atmospheric pressure low temperature plasma jets (APLTPJs) driven by short pulses have recently received great attention because of their potential in biomedical and environmental applications. This potential is due to their user-friendly features, such as low temperature, low risk of arcing, operation at atmospheric pressure, easy handheld operation, and low concentration of ozone generation. Recent experimental observations indicate that an ionization wave exists and propagates along the plasma jet. The plasma jet created by this ionization wave is not a continuous medium but rather consists of a bullet-like-structure known as "Plasma Bullet". More interestingly, these plasma bullets actually have a donut-shaped makeup. The nature of the plasma bullet is especially interesting because it propagates in the ambient air at supersonic velocities without any externally applied electric field. In this dissertation, experimental insights are reported regarding the physical and chemical characteristics of the APLTPJs. The dynamics of the plasma bullet are investigated by means of a high-speed ICCD camera. A plasma bullet propagation model based on the streamer theory is confirmed with adequate explanations. It is also found that a secondary discharge, ignited by the charge accumulation on the dielectric electrode surfaces at the end of the applied voltage, interrupts the plasma bullet propagation due to an opposing current along the ionization channel. The reason for this interesting phenomenon is explained in detail. The plasma bullet comes to an end when the helium mole fraction along the ionization channel, or applied voltage, or both, are less than some critical values. The presence of an inert gas channel in the surrounding air, such as helium or argon, has a critical role in plasma bullet formation and propagation. For this reason, a fluid dynamics study is employed by a commercially available simulation software, COMSOL, based on finite element method. Spatio

  17. Effects of aging on the adhesive properties of poly(lactic acid) by atmospheric air plasma treatment

    OpenAIRE

    Jordá Vilaplana, Amparo; Sánchez Nacher, Lourdes; García Sanoguera, David; Carbonell Verdú, Alfredo; Ferri Azor, José Miguel

    2016-01-01

    The aim of this study was to analyze the durability of a plasma treatment on the surface of poly(lactic acid) (PLA). We used atmospheric-plasma treatment with air to improve the wettability of PLA by evaluating the aging effect under controlled conditions of relative humidity (RH) and temperature (25% RH and 258C). We studied the durability of the atmospheric-plasma treatment by measuring the contact angle, calculating the surface energy, and observing changes in the resistance of th...

  18. Effect of cold atmospheric pressure He-plasma jet on DNA change and mutation

    Science.gov (United States)

    Yaopromsiri, C.; Yu, L. D.; Sarapirom, S.; Thopan, P.; Boonyawan, D.

    2015-12-01

    Cold atmospheric pressure plasma jet (CAPPJ) effect on DNA change was studied for assessment of its safety. The experiment utilized a home-developed CAPPJ using 100% helium to directly treat naked DNA plasmid pGFP (plasmid green fluorescent protein). A traversal electric field was applied to separate the plasma components and both dry and wet sample conditions were adopted to investigate various factor roles in changing DNA. Plasma species were measured by using optical emission spectroscopy. DNA topological form change was analyzed by gel electrophoresis. The plasma jet treated DNA was transferred into bacterial Escherichia coli cells for observing mutation. The results show that the He-CAPPJ could break DNA strands due to actions from charge, radicals and neutrals and potentially cause genetic modification of living cells.

  19. Improving adhesion of powder coating on PEEK composite: Influence of atmospheric plasma parameters

    Science.gov (United States)

    Dupuis, Aurélie; Ho, Thu Huong; Fahs, Ahmad; Lafabrier, Aurore; Louarn, Guy; Bacharouche, Jalal; Airoudj, Aissam; Aragon, Emmanuel; Chailan, Jean-François

    2015-12-01

    In aeronautic industries, powder coatings are increasingly used because of environmental considerations. During the deposition of such a coating on a substrate piece, the main objective is to obtain a good coating/substrate adhesion. In this study, the targeted substrate is a Poly-(Ether EtherKetone)-(PEEK) based composite material. Due to the poor surface energy of PEEK, a surface treatment is necessary in order to enhance its adhesion with the coating. In this purpose, atmospheric plasma treatment has been chosen and the influence of plasma parameters has been studied. Four scan speed nozzles and three gases (Air, N2 and Argon) plasma has been tested. The increase of adhesion with increasing wettability, polarity and nanoroughness has been evidenced. A particular study of the type of grafted polar functionalities according to gas nature allowed to better understand the plasma mechanism and the cross-impact of polarity and nanoroughness in adhesion enhancement.

  20. Cold atmospheric plasma discharged in water and its potential use in cancer therapy

    Science.gov (United States)

    Chen, Zhitong; Cheng, Xiaoqian; Lin, Li; Keidar, Michael

    2017-01-01

    Cold atmospheric plasma (CAP) has emerged as a novel technology for cancer treatment. CAP can directly treat cells and tissue but such direct application is limited to skin or can be invoked as a supplement during open surgery. In this study we report indirect plasma treatment using CAP discharged in deionized (DI) water using three gases as carriers (argon (Ar), helium (He), and nitrogen (N2)). Plasma stimulated water was applied to the human breast cancer cell line (MDA-MB-231). MTT (3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay tests showed that using Ar plasma had the strongest effect on inducing apoptosis in cultured human breast cancer cells. This result is attributed to the elevated production of reactive oxygen species and reactive nitrogen species in water.

  1. Effect of cold atmospheric pressure He-plasma jet on DNA change and mutation

    Energy Technology Data Exchange (ETDEWEB)

    Yaopromsiri, C. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Yu, L.D., E-mail: yuld@thep-center.org [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Sarapirom, S. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Faculty of Science, Maejo University, Bang Khen, Chiang Mai 50290 (Thailand); Thopan, P.; Boonyawan, D. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2015-12-15

    Cold atmospheric pressure plasma jet (CAPPJ) effect on DNA change was studied for assessment of its safety. The experiment utilized a home-developed CAPPJ using 100% helium to directly treat naked DNA plasmid pGFP (plasmid green fluorescent protein). A traversal electric field was applied to separate the plasma components and both dry and wet sample conditions were adopted to investigate various factor roles in changing DNA. Plasma species were measured by using optical emission spectroscopy. DNA topological form change was analyzed by gel electrophoresis. The plasma jet treated DNA was transferred into bacterial Escherichia coli cells for observing mutation. The results show that the He-CAPPJ could break DNA strands due to actions from charge, radicals and neutrals and potentially cause genetic modification of living cells.

  2. High electron mobility thin-film transistors based on Ga{sub 2}O{sub 3} grown by atmospheric ultrasonic spray pyrolysis at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Stuart R., E-mail: s.thomas09@imperial.ac.uk, E-mail: thomas.anthopoulos@imperial.ac.uk; Lin, Yen-Hung; Faber, Hendrik; Anthopoulos, Thomas D., E-mail: s.thomas09@imperial.ac.uk, E-mail: thomas.anthopoulos@imperial.ac.uk [Department of Physics, Blackett Laboratory, Imperial College London, London SW7 2BW (United Kingdom); Adamopoulos, George [Department of Engineering, Engineering Building, Lancaster University, Bailrigg, Lancaster LA1 4YR (United Kingdom); Sygellou, Labrini [Institute of Chemical Engineering and High Temperature Processes (ICEHT), Foundation of Research and Technology Hellas (FORTH), Stadiou Strasse Platani, P.O. Box 1414, Patras GR-265 04 (Greece); Stratakis, Emmanuel [Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology-Hellas (FORTH), Heraklion 71003 (Greece); Materials Science and Technology Department, University, of Crete, Heraklion 71003 (Greece); Pliatsikas, Nikos; Patsalas, Panos A. [Laboratory of Applied Physics, Department of Physics, Aristotle University of Thessaloniki, Thessaloniki GR-54124 (Greece)

    2014-09-01

    We report on thin-film transistors based on Ga{sub 2}O{sub 3} films grown by ultrasonic spray pyrolysis in ambient atmosphere at 400–450 °C. The elemental, electronic, optical, morphological, structural, and electrical properties of the films and devices were investigated using a range of complementary characterisation techniques, whilst the effects of post deposition annealing at higher temperature (700 °C) were also investigated. Both as-grown and post-deposition annealed Ga{sub 2}O{sub 3} films are found to be slightly oxygen deficient, exceptionally smooth and exhibit a wide energy bandgap of ∼4.9 eV. Transistors based on as-deposited Ga{sub 2}O{sub 3} films show n-type conductivity with the maximum electron mobility of ∼2 cm{sup 2}/V s.

  3. Characterization and fatigue damage of plasma sprayed HAp top coat with Ti and HAp/Ti bond coat layers on commercially pure titanium substrate.

    Science.gov (United States)

    Rakngarm, Achariya; Mutoh, Yoshiharu

    2009-10-01

    The surface of commercially pure Ti (cp-Ti) substrate was grit-blasted with Al(2)O(3) powders and then wet-blasted with HAp/Ti mixed powders at room temperature. Then plasma spraying with Ti powders or HAp/Ti mixed powders on the blasted surface was carried out to form a bond coat layer, denoted as T50 and T100 bond coat for the former and HT100 bond coat for the later. The HAp top coat was subsequently sprayed with 100 mum thickness. The XRD patterns showed that the as-sprayed HT100 bond coat layer was mainly composed of HAp with minor components of Ti and TiO(2). EDS analysis also showed there co-existed HAp and Ti without reaction in the HT100 bond coat layer. Some cracks were observed in the bond coat and the top coat layers after compression-compression and tension-tension fatigue tests. The HT100 bond coat specimen produced less AE signal and a small amount of debonding and cracking in compression-compression fatigue test. The HT100 specimen could survive up to 10 million cycles at stress amplitude of 200 MPa, which is high enough compared to the maximum stress in bones: the order of 100 MPa. The degree of damage (debonding and cracking) in tension-tension fatigue test was more severe than that in compression-compression fatigue testing.

  4. Potential Industrial Applications of the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) Operating in Ambient Air

    Science.gov (United States)

    Reece Roth, J.

    2004-11-01

    The majority of industrial plasma processing with glow discharges has been conducted at pressures below 10 torr. This tends to limit applications to high value workpieces as a result of the high capital cost of vacuum systems and the production constraints of batch processing. It has long been recognized that glow discharge plasmas would play a much larger industrial role if they could be generated at one atmosphere. The One Atmosphere Uniform Glow Discharge Plasma (OAUGDP), developed at the University of Tennessee's Plasma Sciences Laboratory, is a non-thermal RF plasma operating on displacement currents with the time-resolved characteristics of a classical low pressure DC normal glow discharge. As a glow discharge, the OAUGDP operates with maximum electrical efficiency at the Stoletow point, where the energy input per ion-electron pair is a minimum [1, 2]. Several interdisciplinary teams have investigated potential applications of the OAUGDP. These teams included collaborators from the UTK Textiles and Nonwovens Development Center (TANDEC), and the Departments of Electrical and Computer Engineering, Microbiology, and Food Science and Technology, as well as the NASA Langley Research Center. The potential applications of the OAUGDP have all been at one atmosphere and room temperature, using air as the working gas. These applications include sterilizing medical and dental equipment; sterilizable air filters to deal with the "sick building syndrome"; removal of soot from Diesel engine exhaust; subsonic plasma aerodynamic effects, including flow re-attachment to airfoils and boundary layer modification; electrohydrodynamic (EDH) flow control of working gases; increasing the surface energy of materials; improving the adhesion of paints and electroplated layers: improving the wettability and wickability of fabrics; stripping of photoresist; and plasma deposition and directional etching of potential microelectronic relevance. [1] J. R. Roth, Industrial Plasma Engineering

  5. Mechanisms behind surface modification of polypropylene film using an atmospheric-pressure plasma jet

    Science.gov (United States)

    Shaw, David; West, Andrew; Bredin, Jerome; Wagenaars, Erik

    2016-12-01

    Plasma treatments are common for increasing the surface energy of plastics, such as polypropylene (PP), to create improved adhesive properties. Despite the significant differences in plasma sources and plasma properties used, similar effects on the plastic film can be achieved, suggesting a common dominant plasma constituent and underpinning mechanism. However, many details of this process are still unknown. Here we present a study into the mechanisms underpinning surface energy increase of PP using atmospheric-pressure plasmas. For this we use the effluent of an atmospheric-pressure plasma jet (APPJ) since, unlike most plasma sources used for these treatments, there is no direct contact between the plasma and the PP surface; the APPJ provides a neutral, radical-rich environment without charged particles and electric fields impinging on the PP surface. The APPJ is a RF-driven plasma operating in helium gas with small admixtures of O2 (0-1%), where the effluent propagates through open air towards the PP surface. Despite the lack of charged particles and electric fields on the PP surface, measurements of contact angle show a decrease from 93.9° to 70.1° in 1.4 s and to 35° in 120 s, corresponding to a rapid increase in surface energy from 36.4 mN m-1 to 66.5 mN m-1 in the short time of 1.4 s. These treatment effects are very similar to what is found in other devices, highlighting the importance of neutral radicals produced by the plasma. Furthermore, we find an optimum percentage of oxygen of 0.5% within the helium input gas, and a decrease of the treatment effect with distance between the APPJ and the PP surface. These observed effects are linked to two-photon absorption laser-induced fluorescence spectroscopy (TALIF) measurements of atomic oxygen density within the APPJ effluent which show similar trends, implying the importance of this radical in the surface treatment of PP. Analysis of the surface reveals a two stage mechanism for the production of polar

  6. Gene Transfection Method Using Atmospheric Pressure Dielectric-Barrier Discharge Plasmas

    Science.gov (United States)

    Sasaki, Shota; Kanzaki, Makoto; Kaneko, Toshiro

    2013-09-01

    Gene transfection which is the process of deliberately introducing nucleic acids into cells is expected to play an important role in medical treatment because the process is necessary for gene therapy and creation of induced pluripotent stem (iPS) cells. However, the conventional transfection methods have some problems, so we focus attention on promising transfection methods by atmospheric pressure dielectric-barrier discharge (AP-DBD) plasmas. AP-DBD He plasmas are irradiated to the living cell covered with genes. Preliminarily, we use fluorescent dye YOYO-1 instead of the genes and use LIVE/DEAD Stain for cell viability test, and we analyze the transfection efficiency and cell viability under the various conditions. It is clarified that the transfection efficiency is strongly dependence on the plasma irradiation time and cell viability rates is high rates (>90%) regardless of long plasma irradiation time. These results suggest that ROS (Reactive Oxygen Species) and electric field generated by the plasma affect the gene transfection. In addition to this (the plasma irradiation time) dependency, we now investigate the effect of the plasma irradiation under the various conditions.

  7. Effects of non-thermal atmospheric plasma on human periodontal ligament mesenchymal stem cells

    Science.gov (United States)

    Miletić, M.; Mojsilović, S.; Okić Đorđević, I.; Maletić, D.; Puač, N.; Lazović, S.; Malović, G.; Milenković, P.; Petrović, Z. Lj; Bugarski, D.

    2013-08-01

    Here we investigate the influences of non-thermal atmospheric plasma on human mesenchymal stem cells isolated from periodontal ligament (hPDL-MSCs). A specially redesigned plasma needle was used as the source of low-temperature plasma and its effects on different hPDL-MSC functions were investigated. Cell cultures were obtained from extracted normal impacted third molars and characterized for their phenotype and multi-potential differentiation. The hPDL-MSCs possessed all the typical MSC properties, including clonogenic ability, high proliferation rate, specific phenotype and multilineage differentiation. The data regarding the interaction of plasma with hPDL-MSCs demonstrated that plasma treatment inhibited the migration of hPDL-MSCs and induced some detachment, while not affecting their viability. Additionally, plasma significantly attenuated hPDL-MSCs' proliferation, but promoted their osteogenic differentiation. The results of this study indicated that a non-thermal plasma offers specific activity with non-destructive properties that can be advantageous for future dental applications.

  8. Cavity-enhanced absorption spectroscopy to characterize atmospheric pressure plasma jets

    Science.gov (United States)

    van Helden, Jean-Pierre; Nave, Andy; Reuter, Stephan; Roepcke, Juergen; Gianella, Michele; Ritchie, Grant

    2016-09-01

    Non-equilibrium atmospheric pressure plasma jets gain more and more interest as their technological applications increase in diverse fields such as material processing and plasma medicine. Hence, it is essential to diagnose the fluxes of the species generated by these plasma sources to identify relevant fundamental processes and to improve process efficiency. Especially for a comprehensive understanding of the kinetics of the transient species involved, high precision measurements of reactive molecular precursors, free radicals and to identify of any short lived species are of crucial importance. However, the detection of transient species in these type of plasmas poses a challenge for diagnostic techniques as the plasmas typically have small dimensions and high density gradients in space and time. We have overcome these limitations by using cavity-enhanced absorption spectroscopy (CEAS). In this contribution, the latest results concerning the detection of transient species in two types of plasma jets employing CEAS in the near- and mid-infrared spectral range will be presented. We will show that with these methods spatially resolved investigations of concentrations in the mm sized effluent of the plasma jet can be achieved.

  9. Comparison of optical emission from nanosecond and femtosecond laser produced plasma in atmosphere and vacuum conditions

    Science.gov (United States)

    Freeman, J. R.; Harilal, S. S.; Diwakar, P. K.; Verhoff, B.; Hassanein, A.

    2013-09-01

    In this study we examine the emission from brass plasma produced by ns and fs laser ablation under both vacuum and atmosphere environments using identical laser fluences in order to better understand the differences in emission features and plasma dynamics. Optical emission spectra show increased continuum and emission from lower-charged ions for ns laser-produced plasma (LPP), while fs plasma emission spectra show emission primarily from excited neutral species with negligible continuum. Plasma excitation temperature and electron density as a function of time show similar trends for both lasers, though fs LPP expansion appears to be approximately two times faster than ns LPP expansion for the conditions studied. Confinement by the ambient gas is shown to significantly enhance and maintain plasma temperature and density and hence, emission, at later times. ICCD images of plasma expansion showed a broader angular distribution for ns LPP, but narrower angular distribution for fs LPP. Images also confirm the significant effect that the ambient environment has in confining plume expansion.

  10. Comparison of optical emission from nanosecond and femtosecond laser produced plasma in atmosphere and vacuum conditions

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, J.R., E-mail: freemaj@purdue.edu; Harilal, S.S., E-mail: sharilal@purdue.edu; Diwakar, P.K., E-mail: pdiwakar@purdue.edu; Verhoff, B., E-mail: bverhoff@purdue.edu; Hassanein, A., E-mail: hassanein@purdue.edu

    2013-09-01

    In this study we examine the emission from brass plasma produced by ns and fs laser ablation under both vacuum and atmosphere environments using identical laser fluences in order to better understand the differences in emission features and plasma dynamics. Optical emission spectra show increased continuum and emission from lower-charged ions for ns laser-produced plasma (LPP), while fs plasma emission spectra show emission primarily from excited neutral species with negligible continuum. Plasma excitation temperature and electron density as a function of time show similar trends for both lasers, though fs LPP expansion appears to be approximately two times faster than ns LPP expansion for the conditions studied. Confinement by the ambient gas is shown to significantly enhance and maintain plasma temperature and density and hence, emission, at later times. ICCD images of plasma expansion showed a broader angular distribution for ns LPP, but narrower angular distribution for fs LPP. Images also confirm the significant effect that the ambient environment has in confining plume expansion. - Highlights: • Emission from ns and fs LIBS plumes are compared under different pressure environments. • Ablation mechanisms for each laser are used to explain different emission features. • Ambient pressure plays a critical role in plume temperature and density evolution. • Visible emission from fs LIBS plume is almost entirely from neutral species. • Spectra collection time delay is shown to be very important in improving S/N and S/B.

  11. Minimally-Invasive Gene Transfection by Chemical and Physical Interaction of Atmospheric Pressure Plasma Flow

    Science.gov (United States)

    Kaneko, Toshiro

    2014-10-01

    Non-equilibrium atmospheric pressure plasma irradiated to the living-cell is investigated for medical applications such as gene transfection, which is expected to play an important role in molecular biology, gene therapy, and creation of induced pluripotent stem (iPS) cells. However, the conventional gene transfection using the plasma has some problems that the cell viability is low and the genes cannot be transferred into some specific lipid cells, which is attributed to the unknown mechanism of the gene transfection using the plasma. Therefore, the time-controlled atmospheric pressure plasma flow is generated and irradiated to the living-cell suspended solution for clarifying the transfection mechanism toward developing highly-efficient and minimally- invasive gene transfection system. In this experiment, fluorescent dye YOYO-1 is used as the simulated gene and LIVE/DEAD Stain is simultaneously used for cell viability assay. By the fluorescence image, the transfection efficiency is calculated as the ratio of the number of transferred and surviving cells to total cell count. It is clarified that the transfection efficiency is significantly increased by the short-time (90%). This result indicates that the physical effects such as the electric field caused by the charged particles arriving at the surface of the cell membrane, and chemical effects associated with plasma-activated products in solution act synergistically to enhance the cell-membrane transport with low-damage. This work was supported by JSPS KAKENHI Grant Number 24108004.

  12. Cold atmospheric gas plasma disinfection of chicken meat and chicken skin contaminated with Listeria innocua.

    Science.gov (United States)

    Noriega, Estefanía; Shama, Gilbert; Laca, Adriana; Díaz, Mario; Kong, Michael G

    2011-10-01

    Gas plasmas generated at atmospheric pressure and ambient temperatures offer a possible decontamination method for poultry products. The efficacy of cold atmospheric gas plasmas for decontaminating chicken skin and muscle inoculated with Listeria innocua was examined. Optimization of operating conditions for maximal bacterial inactivation was first achieved using membrane filters on which L. innocua had been deposited. Higher values of AC voltage, excitation frequency and the presence of oxygen in the carrier gas resulted in the greatest inactivation efficiency, and this was confirmed with further studies on chicken muscle and skin. Under optimal conditions, a 10 s treatment gave > 3 log reductions of L. innocua on membrane filters, an 8 min treatment gave 1 log reduction on skin, and a 4 min treatment gave > 3 log reductions on muscle. These results show that the efficacy of gas plasma treatment is greatly affected by surface topography. Scanning electron microscopy (SEM) images of chicken muscle and skin revealed surface features wherein bacteria could effectively be protected from the chemical species generated within the gas plasma. The developments in gas plasma technology necessary for its commercial application to foods are discussed. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Synthesis and Characterization of Nanofibrous Polyaniline Thin Film Prepared by Novel Atmospheric Pressure Plasma Polymerization Technique

    Directory of Open Access Journals (Sweden)

    Choon-Sang Park

    2016-01-01

    Full Text Available This work presents a study on the preparation of plasma-polymerized aniline (pPANI nanofibers and nanoparticles by an intense plasma cloud type atmospheric pressure plasma jets (iPC-APPJ device with a single bundle of three glass tubes. The nano size polymer was obtained at a sinusoidal wave with a peak value of 8 kV and a frequency of 26 kHz under ambient air. Discharge currents, photo-sensor amplifier, and optical emission spectrometer (OES techniques were used to analyze the plasma produced from the iPC-APPJ device. Field emission scanning electron microscopy (FE-SEM, transmission electron microscopy (TEM, Fourier transform infrared spectroscopy (FT-IR, gas chromatography-mass spectrometry (GC-MS, and gel permeation chromatography (GPC techniques were used to analyze the pPANI. FE-SEM and TEM results show that pPANI has nanofibers, nanoparticles morphology, and polycrystalline characteristics. The FT-IR and GC-MS analysis show the characteristic polyaniline peaks with evidence that some quinone and benzene rings are broken by the discharge energy. GPC results show that pPANI has high molecular weight (Mw, about 533 kDa with 1.9 polydispersity index (PDI. This study contributes to a better understanding on the novel growth process and synthesis of uniform polyaniline nanofibers and nanoparticles with high molecular weights using the simple atmospheric pressure plasma polymerization technique.

  14. DNA damage in oral cancer and normal cells induced by nitrogen atmospheric pressure plasma jets

    Science.gov (United States)

    Han, Xu; Kapaldo, James; Liu, Yueying; Stack, M. Sharon; Ptasinska, Sylwia

    2015-09-01

    Nitrogen atmospheric pressure plasma jets (APPJs) have been shown to effectively induce DNA double strand breaks in SCC25 oral cancer cells. The APPJ source constructed in our laboratory operates based on dielectric barrier discharge. It consists of two copper electrodes alternatively wrapping around a fused silica tube with nitrogen as a feed gas. It is generally more challenging to ignite plasma in N2 atmosphere than in noble gases. However, N2 provides additional advantages such as lower costs compared to noble gases, thus this design can be beneficial for the future long-term clinical use. To compare the effects of plasma on cancer cells (SCC25) and normal cells (OKF), the cells from both types were treated at the same experimental condition for various treatment times. The effective area with different damage levels after the treatment was visualized as 3D maps. The delayed damage effects were also explored by varying the incubation times after the treatment. All of these studies are critical for a better understanding of the damage responses of cellular systems exposed to the plasma radiation, thus are useful for the development of the advanced plasma cancer therapy. The research described herein was supported by the Division of Chemical Sciences, Geosciences and Biosciences, Basic Energy Sciences, Office of Science, United States Department of Energy through Grant No. DE-FC02-04ER15533.

  15. Evolutionary clade affects resistance of Clostridium difficile spores to Cold Atmospheric Plasma

    Science.gov (United States)

    Connor, Mairéad; Flynn, Padrig B.; Fairley, Derek J.; Marks, Nikki; Manesiotis, Panagiotis; Graham, William G.; Gilmore, Brendan F.; McGrath, John W.

    2017-02-01

    Clostridium difficile is a spore forming bacterium and the leading cause of colitis and antibiotic associated diarrhoea in the developed world. Spores produced by C. difficile are robust and can remain viable for months, leading to prolonged healthcare-associated outbreaks with high mortality. Exposure of C. difficile spores to a novel, non-thermal atmospheric pressure gas plasma was assessed. Factors affecting sporicidal efficacy, including percentage of oxygen in the helium carrier gas admixture, and the effect on spores from different strains representing the five evolutionary C. difficile clades was investigated. Strains from different clades displayed varying resistance to cold plasma. Strain R20291, representing the globally epidemic ribotype 027 type, was the most resistant. However all tested strains displayed a ~3 log reduction in viable spore counts after plasma treatment for 5 minutes. Inactivation of a ribotype 078 strain, the most prevalent clinical type seen in Northern Ireland, was further assessed with respect to surface decontamination, pH, and hydrogen peroxide concentration. Environmental factors affected plasma activity, with dry spores without the presence of organic matter being most susceptible. This study demonstrates that cold atmospheric plasma can effectively inactivate C. difficile spores, and highlights factors that can affect sporicidal activity.

  16. Surface modification of polyester synthetic leather with tetramethylsilane by atmospheric pressure plasma

    Energy Technology Data Exchange (ETDEWEB)

    Kan, C.W., E-mail: tccwk@polyu.edu.hk [Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Kwong, C.H. [Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Ng, S.P. [Hong Kong Community College, The Hong Kong Polytechnic University (Hong Kong)

    2015-08-15

    Highlights: • Atmospheric pressure plasma treatment improved surface performance of polyester synthetic leather with tetramethylsilane. • XPS and FTIR confirmed the deposition of organosilanes on the sample's surface. • Contact angle increases to 138° after plasma treatment. - Abstract: Much works have been done on synthetic materials but scarcely on synthetic leather owing to its surface structures in terms of porosity and roughness. This paper examines the use of atmospheric pressure plasma (APP) treatment for improving the surface performance of polyester synthetic leather by use of a precursor, tetramethylsilane (TMS). Plasma deposition is regarded as an effective, simple and single-step method with low pollution. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) confirm the deposition of organosilanes on the sample's surface. The results showed that under a particular combination of treatment parameters, a hydrophobic surface was achieved on the APP treated sample with sessile drop static contact angle of 138°. The hydrophobic surface is stable without hydrophilic recovery 30 days after plasma treatment.

  17. Pulmonary and heart diseases with inhalation of atmospheric pressure plasma flow

    Science.gov (United States)

    Hirata, Takamichi; Murata, Shigeru; Kishimoto, Takumi; Tsutsui, Chihiro; Kondo, Akane; Mori, Akira

    2012-10-01

    We examined blood pressure in the abdominal aorta of mini pig under plasma inhalation of atmospheric pressure plasma flow. The coaxial atmospheric pressure plasma source has a tungsten wire inside a glass capillary, that is surrounded by a grounded tubular electrode. Plasma was generated under the following conditions; applied voltage: 8 kVpp, frequency: 3 kHz, and helium (He) gas flow rate: 1 L/min. On the other hand, sphygmomanometry of a blood vessel proceeded using a device comprising a disposable force transducer, and a bedside monitor for simultaneous electrocardiography and signal pressure measurements. We directly measured Nitric oxide (NO) using a catheter-type NO sensor placed in the coronary sinus through an angiography catheter from the abdomen. Blood pressure decreased from 110/65 to 90/40 mm Hg in the animals in vivo under plasma inhalation. The NO concentration in the abdominal aorta like the blood pressure, reached a maximum value at about 40 s and then gradually decreased.

  18. Formation of SiC nanoparticles in an atmospheric microwave plasma

    Directory of Open Access Journals (Sweden)

    Martin Vennekamp

    2011-10-01

    Full Text Available We describe the formation of SiC nanopowder using an atmospheric argon microwave plasma with tetramethylsilane (TMS as precursor. The impact of several process conditions on the particle size of the product is experimentally investigated. Particles with sizes ranging from 7 nm to about 20 nm according to BET and XRD measurements are produced. The dependency of the particle size on the process parameters is evaluated statistically and explained with growth-rate equations derived from the theory of Ostwald ripening. The results show that the particle size is mainly influenced by the concentration of the precursor material in the plasma.

  19. Fluoropolymer coated alanine films treated by atmospheric pressure plasmas − In comparison with gamma irradiation

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Bardenshtein, Alexander; Morgen, Per

    2017-01-01

    Fluoropolymer coated alanine films are treated by a dielectric barrier discharge and a gliding arc at atmospheric pressure as well as with gamma irradiation. The film surfaces and the underlying bulk materials are characterized before and after each treatment. The fluorine content decreases...... and the oxygen content increases at the fluoropolymer surfaces, while deposition of specific plasma energies in the alanine films is detected by electron paramagnetic resonance spectroscopy, indicating that not only the fluoropolymer surfaces but also the bulk alanine materials are modified. Differences...... of surface and bulk modification effects between the two plasma treatments are discussed in detail....

  20. Atmospheric Pressure Plasma Jet as a Dry Alternative to Inkjet Printing in Flexible Electronics

    Science.gov (United States)

    Gandhiraman, Ram Prasad; Lopez, Arlene; Koehne, Jessica; Meyyappan, M.

    2016-01-01

    We have developed an atmospheric pressure plasma jet printing system that works at room temperature to 50 deg C unlike conventional aerosol assisted techniques which require a high temperature sintering step to obtain desired thin films. Multiple jets can be configured to increase throughput or to deposit multiple materials, and the jet(s) can be moved across large areas using a x-y stage. The plasma jet has been used to deposit carbon nanotubes, graphene, silver nanowires, copper nanoparticles and other materials on substrates such as paper, cotton, plastic and thin metal foils.

  1. Decontamination of a rotating cutting tool during operation by means of atmospheric pressure plasmas

    DEFF Research Database (Denmark)

    Leipold, Frank; Kusano, Yukihiro; Hansen, F.

    2010-01-01

    The decontamination of a rotating cutting tool used for slicing in the meat industry by means of atmospheric pressure plasmas is investigated. The target is Listeria monocytogenes, a bacterium which causes listeriosis and can be found in plants and food. The non-pathogenic species, Listeria innocua...... of the whole cutting tool. A log 5 reduction of L. innocua is obtained after 340 s of plasma operation. The temperature of the knife after treatment was found to be below 30 °C. The design of the setup allows a decontamination during slicing operation....

  2. Plasma-Sprayed Ti6Al4V Alloy Composite Coatings Reinforced with In Situ Formed TiB-TiN

    Science.gov (United States)

    Anand, Akrity; Das, Mitun; Kundu, Biswanath; Balla, Vamsi Krishna; Bodhak, Subhadip; Gangadharan, S.

    2017-11-01

    Plasma spraying was used to deposit premixed Ti6Al4V + 15 wt.% BN powder on titanium substrate to fabricate Ti6Al4V matrix composite coatings reinforced with in situ synthesized TiB-TiN. The formation of in situ TiB-TiN reinforcements increased with plasma power. The in situ reaction appears to be complete under present experimental conditions but with considerable oxidation of Ti in the composite coatings. The hardness of composite coatings was 7 times higher (855HV), and the in vitro wear rate (2.4 × 10-5 mm3/N m) was one order of magnitude less than that of titanium substrate. However, the microstructural non-uniformity decreased the corrosion resistance of these composite coatings in Hank's balanced salt solution.

  3. Plasma-Sprayed Ti6Al4V Alloy Composite Coatings Reinforced with In Situ Formed TiB-TiN

    Science.gov (United States)

    Anand, Akrity; Das, Mitun; Kundu, Biswanath; Balla, Vamsi Krishna; Bodhak, Subhadip; Gangadharan, S.

    2017-12-01

    Plasma spraying was used to deposit premixed Ti6Al4V + 15 wt.% BN powder on titanium substrate to fabricate Ti6Al4V matrix composite coatings reinforced with in situ synthesized TiB-TiN. The formation of in situ TiB-TiN reinforcements increased with plasma power. The in situ reaction appears to be complete under present experimental conditions but with considerable oxidation of Ti in the composite coatings. The hardness of composite coatings was 7 times higher (855HV), and the in vitro wear rate (2.4 × 10-5 mm3/N m) was one order of magnitude less than that of titanium substrate. However, the microstructural non-uniformity decreased the corrosion resistance of these composite coatings in Hank's balanced salt solution.

  4. Role of ambient dielectric in propagation of Ar atmospheric pressure nonequilibrium plasma jets

    Science.gov (United States)

    Song, Jian; Tang, Jingfeng; Wang, Youyin; Wei, Liqiu; Ren, Chunsheng; Yu, Daren

    2015-05-01

    A single-electrode atmospheric pressure nonequilibrium plasma jet surrounded with different ambient dielectrics is investigated driven by AC power supply. Another three ambient dielectrics, distilled water, ethanol, and carbon tetrachloride, are adopted to compare with air. By examining electrical and optical characteristics, it was found that the molecular polarity of ambient dielectrics had its significant effect on the propagation of atmospheric pressure nonequilibrium plasma jets. When the polarization of molecules was enhanced, the discharge current and the bullet velocity were also increased. For nonpolar dielectric of carbon tetrachloride, this was mainly resulted from the electron polarization in the built-in electric field. For polar dielectrics of ethanol and distilled water, in addition to the electron polarization, orientation polarization was the main cause for the further increase in discharge current and bullet velocity.

  5. Mycotoxin Decontamination of Food: Cold Atmospheric Pressure Plasma versus "Classic" Decontamination.

    Science.gov (United States)

    Hojnik, Nataša; Cvelbar, Uroš; Tavčar-Kalcher, Gabrijela; Walsh, James L; Križaj, Igor

    2017-04-28

    Mycotoxins are secondary metabolites produced by several filamentous fungi, which frequently contaminate our food, and can result in human diseases affecting vital systems such as the nervous and immune systems. They can also trigger various forms of cancer. Intensive food production is contributing to incorrect handling, transport and storage of the food, resulting in increased levels of mycotoxin contamination. Mycotoxins are structurally very diverse molecules necessitating versatile food decontamination approaches, which are grouped into physical, chemical and biological techniques. In this review, a new and promising approach involving the use of cold atmospheric pressure plasma is considered, which may overcome multiple weaknesses associated with the classical methods. In addition to its mycotoxin destruction efficiency, cold atmospheric pressure plasma is cost effective, ecologically neutral and has a negligible effect on the quality of food products following treatment in comparison to classical methods.

  6. Mycotoxin Decontamination of Food: Cold Atmospheric Pressure Plasma versus “Classic” Decontamination

    Science.gov (United States)

    Hojnik, Nataša; Cvelbar, Uroš; Tavčar-Kalcher, Gabrijela; Walsh, James L.; Križaj, Igor

    2017-01-01

    Mycotoxins are secondary metabolites produced by several filamentous fungi, which frequently contaminate our food, and can result in human diseases affecting vital systems such as the nervous and immune systems. They can also trigger various forms of cancer. Intensive food production is contributing to incorrect handling, transport and storage of the food, resulting in increased levels of mycotoxin contamination. Mycotoxins are structurally very diverse molecules necessitating versatile food decontamination approaches, which are grouped into physical, chemical and biological techniques. In this review, a new and promising approach involving the use of cold atmospheric pressure plasma is considered, which may overcome multiple weaknesses associated with the classical methods. In addition to its mycotoxin destruction efficiency, cold atmospheric pressure plasma is cost effective, ecologically neutral and has a negligible effect on the quality of food products following treatment in comparison to classical methods. PMID:28452957

  7. Effect of Atmospheric Pressure Plasma and Subsequent Enzymatic Treatment on Flax Fabrics

    Science.gov (United States)

    Zhong, Shaofeng; Yang, Bin; Ou, Qiongrong

    2015-09-01

    The objective is to investigate the effect of atmospheric pressure dielectric barrier discharge (APDBD) plasma and subsequent cellulase enzyme treatment on the properties of flax fabrics. The changes of surface morphology and structure, physico-mechanical properties, hydrophilicity, bending properties, whiteness, and dyeing properties of the treated substrate were investigated. The results indicated that atmospheric pressure dielectric barrier discharge plasma pre-treatment and subsequent cellulase enzyme treatment could diminish the hairiness of flax fabrics, endowing the flax fabrics with good bending properties, water uptake and fiber accessibility while keeping their good mechanical properties compared with those treated with cellulase enzyme alone. supported by the Science and Technology Project of the Education Department of Zhejiang Province, China (No. Y201432680) and the Professional Leaders Leading Project of the Education Department of Zhejiang Province, China (No. lj2013131), the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institutions of the Education Department of Zhejiang Province, China (No. 1097802072012001)

  8. PLASMA SPRAYED Al₂O₃-13 WT.%TiO₂ COATING SEALED WITH ORGANIC-INORGANIC HYBRID AGENT AND ITS CORROSION RESISTANCE IN ACID ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Zehua Zhou

    2016-07-01

    Full Text Available A novel organic-inorganic hybrid material of γ-methacryloxypropyltrime-thoxysilane (KH570 -SiO₂ was fabricated by Sol-Gel method. The hybrid material was used as the sealing agent for the plasma sprayed Al₂O₃-13 wt.% TiO₂ coating. Infrared spectrum and grafted mechanism of the hybrid agent (HA were studied. Moreover, morphology and porosity, as well as characteristics of immersion plus electrochemical corrosion in acid environment of the coating with and without sealing treatment were evaluated, compared with those of the coating sealed with the conventional silicone resin agent (SRA. The results reveal that KH570 was successfully grafted onto the surface of SiO₂. The HA film sealed on the surface of the coating presents a little better quality than the SRA film. The porosities of the coatings after the sealing treatment decreased. Furthermore, the sealing treatment can improve efficiently the corrosion resistance of the coating in 5 vol.% HCl solution. The hybrid sealing agent can become a candidate for the plasma sprayed Al₂O₃-13 wt.% TiO₂ coating used in acid environment to overcome some disadvantages of organic agents such as severely environmental pollution.

  9. Cracking caused by cutting of plasma-sprayed hydroxyapatite coatings and its relation to the structural features of coatings deposited at different initial substrate temperatures

    Directory of Open Access Journals (Sweden)

    Gligorijević Bojan R.

    2017-01-01

    Full Text Available The present study estimated the cracking phenomenon in as-plasma-sprayed hydroxylapatite coatings (HACs after they were being subjected to the severe cutting conditions in the direction perpendicular to the coating/substrate interface. In order to evaluate the effects of substrate preheating on the occurrence of micro-cracks, the HACs were deposited at different initial substrate temperatures (TS = 20, 100 and 200°C. The changes in phase composition and HA splat morphology with TS were observed and were correlated with the cracking occurrence. The results showed that severe cutting conditions introduced a localized cracking in the regions of HACs dominantly attributed to the brittle hydroxyl-deficient amorphous calcium phosphate (ACP phase. This effect was particularly observable in the HACs deposited without preheating of substrate. On the other hand, the preheating of substrate reduced the presence of micro-cracks and caused insignificant changes in the average local phase composition. In HACs deposited with preheating of substrate, the HA splats (of which HACs are composed were thinner and recrystallized HA regions seemed smaller in size and more evenly distributed. These results implied potentially important roles of the HA splat formation mechanism on the distribution of ACP and recrystallized HA regions in the as-plasma-sprayed HACs and the cracking resistance of HACs. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR 34022

  10. Non-thermal atmospheric plasma brush induces HEMA grafting onto dentin collagen

    Science.gov (United States)

    Chen, Mingsheng; Zhang, Ying; Dusevich, Vladimir; Liu, Yi; Yu, Qingsong; Wang, Yong

    2014-01-01

    Objective Non-thermal atmospheric plasma (NTAP) brush has been regarded as a promising technique to enhance dental interfacial bonding. However, the principal enhancement mechanisms have not been well identified. In this study, the effect of non-thermal plasmas on grafting of HEMA, a typical dental monomer, onto dentin collagen thin films was investigated. Methods Human dentin was sectioned into 10-um-thick films. After total demineralization in 0.5 M EDTA solution for 30 min, the dentin collagen films were water-rinsed, air-dried, treated with 35 wt% HEMA aqueous solution. The films were then subject to plasma-exposure under a NTAP brush with different time (1–8 min) / input power (5–15 w). For comparison, the dentin collagen films were also treated with the above HEMA solution containing photo-initiators, then subject to light-curing. After plasma-exposure or light-curing, the HEMA-collagen films were rinsed in deionized water, and then examined by FTIR spectroscopy and TEM. Results The FITR results indicated that plasma-exposure could induce significant HEMA grafting onto dentin collagen thin films. In contrast, light-curing led to no detectable interaction of HEMA with dentin collagen. Quantitative IR spectral analysis (i.e., 1720/3075 or 749/3075, HEMA/collagen ratios) further suggested that the grafting efficacy of HEMA onto the plasma-exposed collagen thin films strongly depended on the treatment time and input power of plasmas. TEM results indicated that plasma treatment did not alter collagen’s banding structure. Significance The current study provides deeper insight into the mechanism of dental adhesion enhancement induced by non-thermal plasmas treatment. The NTAP brush could be a promising method to create chemical bond between resin monomers and dentin collagen. PMID:25458523

  11. Synthesis of magnetic nanoparticles by atmospheric-pressure glow discharge plasma-assisted electrolysis

    Science.gov (United States)

    Shirai, Naoki; Yoshida, Taketo; Uchida, Satoshi; Tochikubo, Fumiyoshi

    2017-07-01

    For the synthesis of magnetic nanoparticles (NPs), we used plasma-assisted electrolysis in which atmospheric-pressure DC glow discharge using a liquid electrode is combined with electrolysis. The solution surface is exposed to positive ions or electrons in plasma. To synthesize magnetic NPs, aqueous solutions of FeCl2 or an iron electrode immersed in liquid was used to supply iron ions in the liquid. Magnetic NPs were synthesized at the plasma-liquid interface upon the electron irradiation of the liquid surface. In the case of using aqueous solutions of FeCl2, the condition of magnetic NP synthesis depended on the gas species of plasma and the chemical agent in the liquid for controlling oxidization. The amount of magnetic NPs synthesized using plasma is not very large. On the other hand, in the case of using an iron electrode immersed in NaCl solution, magnetic NPs were synthesized without using FeCl2 solutions. When plasma-assisted electrolysis was operated, the iron electrode eluted Fe cations, resulting in the formation of magnetic NPs at the plasma-liquid interface. Magnetic NP synthesis depended on the concentration of NaCl solution and discharge current. The magnetic NPs were identified to be magnetite. By using this method, more magnetite NPs were synthesized than in the case of plasma-assisted electrolysis with FeCl2 aqueous solutions. The pH of the liquid used in plasma-assisted electrolysis was important for the synthesis of magnetite NPs.

  12. Temperature diagnostics of a non-thermal plasma jet at atmospheric pressure

    Science.gov (United States)

    Schäfer, Jan

    2013-09-01

    The study reflects the concept of the temperature as a physical quantity resulting from the second thermodynamic law. The reliability of different approaches of the temperature diagnostics of open non-equilibrium systems is discussed using examples of low temperature atmospheric pressure discharges. The focus of this work is a miniaturized non-thermal atmospheric pressure plasma jet for local surface treatment at ambient atmosphere. The micro-discharge is driven with a capacitively coupled radio frequency electric field at 27.12 MHz and fed with argon at rates of about 1 slm through the capillary with an inner diameter of 4 mm. The discharge consists of several contracted filaments with diameter around 300 μm which are rotating azimuthally in the capillary in a self-organized manner. While the measured temperatures of the filament core exceed 700 K, the heat impact on a target below the plasma jet remains limited leading to target temperatures below 400 K. Different kinds of temperatures and energy transport processes are proposed and experimentally investigated. Nevertheless, a reliable and detailed temperature diagnostics is a challenge. We report on a novel diagnostics approach for the spatially and temporally resolved measurement of the gas temperature based on the optical properties of the plasma. Laser Schlieren Deflectometry is adapted to explore temperature profiles of filaments and their behaviour. In parallel, the method demonstrates a fundamental Fermat's principle of minimal energy. Information acquired with this method plays an important role for the optimization of local thin film deposition and surface functionalization by means of the atmospheric pressure plasma jet. The work was supported in part by the Deutsche Forschungsgemeinschaft within SFB-TR 24.

  13. Glow plasma jet - experimental study of a transferred atmospheric pressure glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Guerra-Mutis, Marlon H [Mares Oil Ltd., Instituto Colombiano del Petroleo (ICP) - ECOPETROL (Colombia); U, Carlos V Pelaez [Laboratorio de Control Magnetico de Fluidos, Instituto Colombiano del Petroleo (ICP) - ECOPETROL (Colombia); H, Rafael Cabanzo [Laboratorio de Espectroscopia Atomico-Molecular (LEAM) - UIS (Colombia)

    2003-05-01

    In this paper we present the experimental study of a glow plasma jet (GPJ) obtained from a transferred atmospheric pressure glow discharge (APGD) operating at 60 Hz. The characterization of the emission spectra for both electrical discharges is presented and the electrical circuit features for APGD generation are discussed. The potentiality of GPJ as a source of active species for depletion of contaminants in liquid hydrocarbon fractions is also established.

  14. Effect of nozzle profile on gas mixing in an atmospheric and low pressure DC plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Rahmane, M.; Soucy, G.; Boulos, M.I. [Univ. of Sherbrooke, Quebec (Canada); Henne, R. [Inst. for Technical Thermodynamics, Stuttgart (Germany)

    1994-12-31

    The study combines enthalpy probe and mass spectrometer measurements in a DC-plasma jet under atmospheric and low pressure conditions. Both, standard cylindrical and laval nozzle were used as anode profiles. A detailed description of the experimental technique is given together with preliminary results. These confirm the role by which enthalpy probe measurements can be used to bridge the gap in temperature range between emission spectroscopic techniques and standard thermocouple probing.

  15. Surface decontamination of eggshells by using non-thermal atmospheric plasma.

    Science.gov (United States)

    Dasan, Beyhan Gunaydin; Yildirim, Tugba; Boyaci, Ismail Hakki

    2018-02-02

    In this study, the possibility of using an effective short time non-thermal plasma (NTP) treatment to inactivate Salmonella enterica serovar Enteritidis on eggshell surface was investigated. The eggshells were artificially contaminated with S. Enteritidis at an initial concentration of 10 7 cfu/egg and then treated with an atmospheric pressure plasma jet by using air as process gas under different experimental settings with various frequencies (20-25kHz) and reference voltages (100-80%), exposure times (60-120s), distances from plasma jet (15 or 40mm) and gas flow rates (2000-3000L/h). The best result was obtained at maximum plasma power of 655W (25kHz-100% V), where S. Enteritidis concentration on egg surface was reduced below the detection limit (10 2 cfu/egg) after 120s of treatment. The temperature remained below 35°C after all plasma treatments in order to minimize the risk of egg quality alterations. Specific measurements demonstrated that there were no negative effects on egg quality after NTP treatment. The effect of plasma process on the egg cuticle was demonstrated by using scanning electron microscopy. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Cold Atmospheric Plasma for Medicine: State of Research and Clinical Application

    Science.gov (United States)

    von Woedtke, Thomas

    2015-09-01

    Basic research in plasma medicine has made excellent progress and resulted in the fundamental insights that biological effects of cold atmospheric plasmas (CAP) are significantly caused by changes of the liquid environment of cells, and are dominated by redox-active species. First CAP sources are CE-certified as medical devices. Main focus of plasma application is on wound healing and treatment of infective skin diseases. Clinical applications in this field confirm the supportive effect of cold plasma treatment in acceleration of healing of chronic wounds above all in cases where conventional treatment fails. Cancer treatment is another actual and emerging field of CAP application. The ability of CAP to kill cancer cells by induction of apoptosis has been proved in vitro. First clinical applications of CAP in palliative care of cancer are realized. In collaboration with Hans-Robert Metelmann, University Medicine Greifswald; Helmut Uhlemann, Klinikum Altenburger Land GmbH Altenburg; Anke Schmidt and Kai Masur, Leibniz Institute for Plasma Science and Technology (INP Greifswald); Renate Schönebeck, Neoplas Tools GmbH Greifswald; and Klaus-Dieter Weltmann, Leibniz Institute for Plasma Science and Technology (INP Greifswald).

  17. Multi-electrodes Atmospheric Pressure Plasma Jet Aiming Bio-applications

    Science.gov (United States)

    Han, Jeon G.; Sahu, B. B.; Shin, K. S.; Lee, J. S.; Hori, M.

    2015-09-01

    For the recent advancement in the field of plasma medicine, there is growing demand for the atmospheric-pressure plasma (APP) jet sources with desired plasma characteristics. In this study, a stable non-thermal low-voltage APP jet device was designed and developed for optical and electrical characterizations. The jet was operated at very low frequency in the range 10-40 KHz, which enabled the generation of low power (~ 7W) plasma with a plasma column diameter of about 5 mm. The jet has a visible radial diameter of approximately 10 mm. Optical emission spectroscopy was used as a diagnostic tool to investigate the generation of plasmas and radical species. Discharge parameters are also measured to evaluate the different operating conditions. The gas temperature measured at the substrate location varies from 300 to 315 K for different gases where the electrical input power ranged from 1 to 7 W. The highly reactive species like OH, O, N2, N2 + and along with the trace of NO are characterized with respect to the different gas flow rate of Ar/He/O2/N2, applied voltages, duty cycles and frequencies to evaluate the capability of the APP jet for future bio-applications.

  18. Reduction in lateral lipid mobility of lipid bilayer membrane by atmospheric pressure plasma irradiation

    Science.gov (United States)

    Suda, Yoshiyuki; Tero, Ryugo; Yamashita, Ryuma; Yusa, Kota; Takikawa, Hirofumi

    2016-03-01

    Plasma medicine is an emerging research field in which various applications of electrical discharge, especially in the form of nonequilibrium plasma at atmospheric pressure, are examined, for example, the application of plasma to biological targets for various purposes such as selective killing of tumor cells and blood stanching. We have focused on the behavior of an artificial cell membrane system at the solid-liquid interface. To evaluate the lateral lipid mobility, we measured the diffusion coefficient of the supported lipid bilayer (SLB) composed of dioleoylphosphatidylcholine with fluorescence recovery after photobleaching by confocal laser scanning microscopy. It was found that the diffusion coefficient was decreased by plasma irradiation and that the diffusion coefficient decreasing rate proceeded with increasing plasma power. We investigated the effects of stimulation with an equilibrium chemical, H2O2, on the SLB and confirmed that the diffusion coefficient did not change at least up to a H2O2 concentration of 5 mM. These results indicate that transient active species generated by plasma play critical roles in the reduction in SLB fluidity. The effects of the two generated major oxidized lipid species, hydroxyl- or hydroperoxy-phosphatidylcholine (PC) and acyl-chain-truncated PCs terminated with aldehyde or carboxyl group, on lateral lipid mobility are discussed.

  19. Application of atmospheric plasma sources in growth and differentiation of plant and mammalian stem cells

    Science.gov (United States)

    Puac, Nevena

    2014-10-01

    The expansion of the plasma medicine and its demand for in-vivo treatments resulted in fast development of various plasma devices that operate at atmospheric pressure. These sources have to fulfill all demands for application on biological samples. One of the sources that meet all the requirements needed for treatment of biological material is plasma needle. Previously, we have used this device for sterilization of planctonic samples of bacteria, MRSA biofilm, for improved differentiation of human periodontal stem cells into osteogenic line and for treatment of plant meristematic cells. It is well known that plasma generates reactive oxygen species (ROS) and reactive nitrogen species (RNS) that strongly affect metabolism of living cells. One of the open issues is to correlate external plasma products (electrons, ions, RNS, ROS, photons, strong fields etc.) with the immediate internal response which triggers or induces effects in the living cell. For that purpose we have studied the kinetics of enzymes which are typical indicators of the identity of reactive species from the plasma created environment that can trigger signal transduction in the cell and ensue cell activity. In collaboration with Suzana Zivkovicm, Institute for Biological Research ``Sinisa Stankovic,'' University of Belgrade; Nenad Selakovic, Institute of Physics, University of Belgrade; Milica Milutinovic, Jelena Boljevic, Institute for Biological Research ``Sinisa Stankovic,'' University of Belgrade; and Gordana Malovic, Zoran Lj. Petrovic, Institute of Physics, University of Belgrade. Grants III41011, ON171037 and ON173024, MESTD, Serbia.

  20. Formation of thermal flow fields and chemical transport in air and water by atmospheric plasma

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Tetsuji; Morfill, Gregor E [Max-Planck Institute for Extraterrestrial Physics, 85748 Garching (Germany); Iwafuchi, Yutaka [Graduate School of Engineering, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 9808577 (Japan); Sato, Takehiko, E-mail: sato@ifs.tohoku.ac.jp [Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 9808577 (Japan)

    2011-05-15

    Cold atmospheric plasma is a potential tool for medical purposes, e.g. disinfection/sterilization. In order for it to be effective and functional, it is crucial to understand the transport mechanism of chemically reactive species in air as well as in liquid. An atmospheric plasma discharge was produced between a platinum pin electrode and the surface of water. The thermal flow field of a cold atmospheric plasma as well as its chemical components was measured. A gas flow with a velocity of around 15 m s{sup -1} to the water's surface was shown to be induced by the discharge. This air flow induced a circulating flow in the water from the discharge point at the water's surface because of friction. It was also demonstrated that the chemical components generated in air dissolved in water and the properties of the water changed. The reactive species were believed to be distributed mainly by convective transport in water, because the variation in the pH profile indicated by a methyl red solution resembled the induced flow pattern.

  1. Etching of polymers, proteins and bacterial spores by atmospheric pressure DBD plasma in air

    Science.gov (United States)

    Kuzminova, A.; Kretková, T.; Kylián, O.; Hanuš, J.; Khalakhan, I.; Prukner, V.; Doležalová, E.; Šimek, M.; Biederman, H.

    2017-04-01

    Many studies proved that non-equilibrium discharges generated at atmospheric pressure are highly effective for the bio-decontamination of surfaces of various materials. One of the key processes that leads to a desired result is plasma etching and thus the evaluation of etching rates of organic materials is of high importance. However, the comparison of reported results is rather difficult if impossible as different authors use diverse sources of atmospheric plasma that are operated at significantly different operational parameters. Therefore, we report here on the systematic study of the etching of nine different common polymers that mimic the different structures of more complicated biological systems, bovine serum albumin (BSA) selected as the model protein and spores of Bacillus subtilis taken as a representative of highly resistant micro-organisms. The treatment of these materials was performed by means of atmospheric pressure dielectric barrier discharge (DBD) sustained in open air at constant conditions. All tested polymers, BSA and spores, were readily etched by DBD plasma. However, the measured etching rates were found to be dependent on the chemical structure of treated materials, namely on the presence of oxygen in the structure of polymers.

  2. Production of stable, non-thermal atmospheric pressure rf capacitive plasmas using gases other than helium or neon

    Science.gov (United States)

    Park, Jaeyoung; Henins, Ivars

    2005-06-21

    The present invention enables the production of stable, steady state, non-thermal atmospheric pressure rf capacitive .alpha.-mode plasmas using gases other than helium and neon. In particular, the current invention generates and maintains stable, steady-state, non-thermal atmospheric pressure rf .alpha.-mode plasmas using pure argon or argon with reactive gas mixtures, pure oxygen or air. By replacing rare and expensive helium with more readily available gases, this invention makes it more economical to use atmospheric pressure rf .alpha.-mode plasmas for various materials processing applications.

  3. Atmospheric Plasma Deposition of SiO2 Films for Adhesion Promoting Layers on Titanium

    Directory of Open Access Journals (Sweden)

    Liliana Kotte

    2014-12-01

    Full Text Available This paper evaluates the deposition of silica layers at atmospheric pressure as a pretreatment for the structural bonding of titanium (Ti6Al4V, Ti15V3Cr3Sn3Al in comparison to an anodizing process (NaTESi process. The SiO2 film was deposited using the LARGE plasma source, a linearly extended DC arc plasma source and applying hexamethyldisiloxane (HMDSO as a precursor. The morphology of the surface was analyzed by means of SEM, while the characterization of the chemical composition of deposited plasma layers was done by XPS and FTIR. The long-term durability of bonded samples was evaluated by means of a wedge test in hot/wet condition. The almost stoichiometric SiO2 film features a good long-term stability and a high bonding strength compared to the films produced with the wet-chemical NaTESi process.

  4. Atmospheric-pressure plasma jet characterization and applications on melanoma cancer treatment (B/16-F10)

    Energy Technology Data Exchange (ETDEWEB)

    Mashayekh, Shahriar [Physics Department, Shahid Beheshti University, G.C., Evin, 19839-63113 Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Rajaee, Hajar; Hassan, Zuhir M. [Imonology Department, Faculty of Medical Science, Tarbiat Modarres University, Tehran (Iran, Islamic Republic of); Akhlaghi, Morteza [Laser-Plasma Research Institute, Shahid Beheshti University, G.C., Evin, 19839-63113 Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Shokri, Babak [Physics Department and Laser-Plasma Research Institute, Shahid Beheshti University, G.C., Evin, 19839-63113 Tehran, Islamic Republic of Iran (Iran, Islamic Republic of)

    2015-09-15

    A new approach in medicine is the use of cold plasma for various applications such as sterilization blood coagulation and cancer cell treatment. In this paper, a pin-to-hole plasma jet for biological applications has been designed and manufactured and characterized. The characterization includes power consumption via Lissajous method, thermal behavior of atmospheric-pressure plasma jet by using Infra-red camera as a novel method and using Speicair software to determine vibrational and transitional temperatures, and optical emission spectroscopy to determine the generated species. Treatment of Melanoma cancer cells (B16/F10) was also implemented, and tetrazolium salt dye (MTT assay) and flow cytometry were used to evaluate viability. Effect of ultraviolet photons on cancerous cells was also observed using an MgF{sub 2} crystal with MTT assay. Finally, in-vivo studies on C57 type mice were also done in order to have a better understanding of the effects in real conditions.

  5. Apparatus and method for atmospheric pressure reactive atom plasma processing for shaping of damage free surfaces

    Science.gov (United States)

    Carr,; Jeffrey, W [Livermore, CA

    2009-03-31

    Fabrication apparatus and methods are disclosed for shaping and finishing difficult materials with no subsurface damage. The apparatus and methods use an atmospheric pressure mixed gas plasma discharge as a sub-aperture polisher of, for example, fused silica and single crystal silicon, silicon carbide and other materials. In one example, workpiece material is removed at the atomic level through reaction with fluorine atoms. In this example, these reactive species are produced by a noble gas plasma from trace constituent fluorocarbons or other fluorine containing gases added to the host argon matrix. The products of the reaction are gas phase compounds that flow from the surface of the workpiece, exposing fresh material to the etchant without condensation and redeposition on the newly created surface. The discharge provides a stable and predictable distribution of reactive species permitting the generation of a predetermined surface by translating the plasma across the workpiece along a calculated path.

  6. Food powder analysis by using transversely excited atmospheric CO2 laser-induced plasma spectroscopy

    Science.gov (United States)

    Khumaeni, Ali; Sukra Lie, Zener; Setiabudi, Wahyu; Hendrik Kurniawan, Koo; Kagawa, Kiichiro

    2015-06-01

    A direct and sensitive analysis of food powder sample has successfully been carried out by utilizing the special characteristics of pulsed transversely excited atmospheric (TEA) CO2 laser. In this study, a food powder was placed in a container made of copper plate and covered by a metal mesh. The container was perpendicularly attached on a metal surface. A high-temperature luminous plasma was induced on a metal surface 5 mm above the mesh. Once the plasma was produced, a strong shock wave was induced, blowing-off of the powder from the container to enter into the plasma to be dissociated and excited. By using this method, a semi-quantitative analysis of food powder was made. The detection limits of Cr in the powdered agar and Cd in the powdered rice were 9 mg/kg and 50 mg/kg, respectively.

  7. Plasma chemistry in an atmospheric pressure Ar/NH3 dielectric barrier discharge

    DEFF Research Database (Denmark)

    Fateev, A.; Leipold, F.; Kusano, Y.

    2005-01-01

    absorption spectroscopy was also employed for the detection of stable products in the exhaust gas. To clarify the different processes for ammonia decomposition, N-2(2 - 10%) was added to the plasma. Modeling of the chemical kinetics in an Ar/NH3 plasma was performed as well. The dominant stable products...... of an atmospheric pressure Ar/NH3 DBD are H-2, N-2 and N2H4. The hydrazine (N2H4) concentration in the plasma and in the exhaust gases at various ammonia concentrations and different discharge powers was measured. Thermal N2H4 decomposition into NH2 radicals may be used for NOx reduction processes....

  8. Sterilization Efficiency of Spore forming Bacteria in Powdery Food by Atmospheric Pressure Plasmas Sterilizer

    Science.gov (United States)

    Nagata, Masayoshi; Tanaka, Masashi; Kikuchi, Yusuke

    2015-09-01

    To provide food sterilization method capable of killing highly heat resistant spore forming bacteria, we have studied effects of plasma treatment method at atmospheric pressure in order to develop a new high speed plasma sterilization apparatus with a low cost and a high efficiency. It is also difficult even for the plasma treatment to sterilize powdery food including spices such as soybean, basil and turmeric. This paper describes that an introduction of mechanical rotation of a treatment space increases the efficiency so that perfect inactivation of spore forming bacteria in these materials by a short treatment time has been demonstrated in our experiments. We also will discuss the sterilization mechanism by dielectric barrier discharge.

  9. Atmospheric-pressure glow plasma synthesis of plasmonic and photoluminescent zinc oxide nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Bilik, N., E-mail: bilik006@umn.edu, E-mail: kortshagen@umn.edu; Greenberg, B. L.; Yang, J.; Kortshagen, U. R., E-mail: bilik006@umn.edu, E-mail: kortshagen@umn.edu [Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Aydil, E. S. [Department of Chemical Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

    2016-06-28

    In this paper, we present a large-volume (non-micro) atmospheric pressure glow plasma capable of rapid, large-scale zinc oxide nanocrystal synthesis and deposition (up to 400 μg/min), whereas in the majority of the literature, nanoparticles are synthesized using micro-scale or filamentary plasmas. The reactor is an RF dielectric barrier discharge with a non-uniform gap spacing. This design encourages pre-ionization during the plasma breakdown, making the discharge uniform over a large volume. The produced zinc oxide nanocrystals typically have diameters ranging from 4 to 15 nm and exhibit photoluminescence at ≈550 nm and localized surface plasmon resonance at ≈1900 cm{sup −1} due to oxygen vacancies. The particle size can be tuned to a degree by varying the gas temperature and the precursor mixing ratio.

  10. Investigation on the effects of the atmospheric pressure plasma on wound healing in diabetic rats.

    Science.gov (United States)

    Fathollah, Sara; Mirpour, Shahriar; Mansouri, Parvin; Dehpour, Ahmad Reza; Ghoranneviss, Mahmood; Rahimi, Nastaran; Safaie Naraghi, Zahra; Chalangari, Reza; Chalangari, Katalin Martits

    2016-02-23

    It is estimated that 15 percent of individuals with diabetes mellitus suffer from diabetic ulcers worldwide. The aim of this study is to present a non-thermal atmospheric plasma treatment as a novel therapy for diabetic wounds. The plasma consists of ionized helium gas that is produced by a high-voltage (8 kV) and high-frequency (6 kHz) power supply. Diabetes was induced in rats via an intravascular injection of streptozotocin. The plasma was then introduced to artificial xerograph wounds in the rats for 10 minutes. Immunohistochemistry assays was performed to determine the level of transforming growth factor (TGF-β1) cytokine. The results showed a low healing rate in the diabetic wounds compared with the wound-healing rate in non-diabetic animals (P healing rate in the non-diabetic rats (P healing in diabetic rats.

  11. Electrical and optical characteristics of atmospheric pressure plasma needle jet driven by neon trasformer

    Science.gov (United States)

    Elfa, Rizan Rizon; Ahmad, Mohd Khairul; Soon, Chin Fhong; Sahdan, Mohd Zainizan; Lias, Jais; Mamat, Mohamad Hafiz; Rusop, Mohamad; Nayan, Nafarizal

    2017-09-01

    The atmospheric pressure plasma needle jet driven by double sinusoidal waveform of neon transformer is reported in this paper. The commercial neon transformer produces about 5 kV of peak sinusoidal voltages and 35 kHz of frequency. Argon gas has been used as discharge gas for this system since the discharge was easily developed rather than using helium gas. In addition, argon gas is three times cheaper than helium gas. The electrical property of the argon discharge has been analyzed in details by measuring its voltage, current and power during the discharge process. Interestingly, it has been found that the total power on the inner needle electrode was slightly lower than that of outer electrode. This may be due to the polarization charges that occurred at inner needle electrode. Then, further investigation to understand the discharge properties was carried out using optical emission spectroscopy (OES) analysis. During OES measurements, two positions of plasma discharge are measured by aligning the quartz optical lens and spectrometer fiber. The OH emission intensity was found higher than that of N2 at the plasma orifice. However, OH emission intensity was lower at 1.5 cm distance from orifice which may be due to penning ionization effect. These results and understanding are essential for surface modification and biomedical applications of atmospheric pressure plasma needle jet.

  12. Effects of gas atmospheres on poly(lactic acid) film in acrylic acid plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yun, E-mail: yun.zhaotju@yahoo.com [Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Turin (Italy); Fina, Alberto [Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino – sede di Alessandria, V. T. Michel 5, 15121 Alessandria (Italy); Venturello, Alberto; Geobaldo, Francesco [Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Turin (Italy)

    2013-10-15

    Plasma polymerized acrylic acid (AA) coatings were deposited on poly(lactic acid) (PLA) films in various gas atmospheres during the pre-treatment of PLA and the deposition of AA, respectively. Therefore, this work was twofold: the argon pretreated PLA films followed by a deposition in argon were investigated against the mixture of argon and oxygen pretreated ones under the same deposition conditions; the plasma deposition of AA operating in different atmospheres (argon, oxygen and nitrogen) was employed to modify the pretreated PLA in oxygen. Chemical and physical changes on the plasma-treated surfaces were examined using contact angle, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and attenuated total reflection infrared (ATR-FTIR) analysis. The results showed that the discharge gas can have a significant influence on the chemical composition of the PLA surfaces: oxygen plasmas introduced oxygen-containing groups in company with surface etching in pretreatment and deposition, while argon discharges was able to achieve much better hydrophilic behavior and high retention ratio of poly(acrylic acid) (PAA) coating before and after washing in water.

  13. Eradication of Pseudomonas aeruginosa biofilms by atmospheric pressure non-thermal plasma.

    Directory of Open Access Journals (Sweden)

    Mahmoud Y Alkawareek

    Full Text Available Bacteria exist, in most environments, as complex, organised communities of sessile cells embedded within a matrix of self-produced, hydrated extracellular polymeric substances known as biofilms. Bacterial biofilms represent a ubiquitous and predominant cause of both chronic infections and infections associated with the use of indwelling medical devices such as catheters and prostheses. Such infections typically exhibit significantly enhanced tolerance to antimicrobial, biocidal and immunological challenge. This renders them difficult, sometimes impossible, to treat using conventional chemotherapeutic agents. Effective alternative approaches for prevention and eradication of biofilm associated chronic and device-associated infections are therefore urgently required. Atmospheric pressure non-thermal plasmas are gaining increasing attention as a potential approach for the eradication and control of bacterial infection and con