Plasma sprayed coatings on crankshaft used steels

Science.gov (United States)

Mahu, G.; Munteanu, C.; Istrate, B.; Benchea, M.

2017-08-01

Plasma spray coatings may be an alternative to conventional heat treatment of main journals and crankpins of the crankshaft. The applications of plasma coatings are various and present multiple advantages compared to electric arc wire spraying or flame spraying. The study examines the layers sprayed with the following powders: Cr3C2- 25(Ni 20Cr), Al2O3- 13TiO2, Cr2O3-SiO2- TiO2 on the surface of steels used in the construction of a crankshaft (C45). The plasma spray coatings were made with the Spray wizard 9MCE facility at atmospheric pressure. The samples were analyzed in terms of micro and morphological using optical microscopy, scanning electron microscopy and X-ray diffraction. Wear tests on samples that have undergone simulates extreme working conditions of the crankshafts. In order to emphasize adherence to the base material sprayed layer, were carried out tests of microscratches and micro-indentation. Results have showed a relatively compact morphological aspect given by the successive coatings with splat-like specific structures. Following the microscratch analysis it can be concluded that Al2O3-13TiO2 coating has a higher purpose in terms of hardness compared to Cr3C2-(Ni 20Cr) and Cr2O3-SiO2- TiO2 powders. Thermal coatings of the deposited powders have increased the mechanical properties of the material. The results stand to confirm that plasma sprayed Al2O3-13TiO2 powder is in fact a efficient solution for preventing mechanical wear, even with a faulty lubrication system.

Experiments on aerosol removal by high-pressure water spray

Energy Technology Data Exchange (ETDEWEB)

Corno, Ada del, E-mail: delcorno@rse-web.it [RSE, Power Generation Technologies and Materials Dept, via Rubattino 54, I-20134 Milano (Italy); Morandi, Sonia, E-mail: morandi@rse-web.it [RSE, Power Generation Technologies and Materials Dept, via Rubattino 54, I-20134 Milano (Italy); Parozzi, Flavio, E-mail: parozzi@rse-web.it [RSE, Power Generation Technologies and Materials Dept, via Rubattino 54, I-20134 Milano (Italy); Araneo, Lucio, E-mail: lucio.araneo@polimi.it [Politecnico di Milano, Department of Energy, via Lambruschini 4A, I-20156 Milano (Italy); CNR-IENI, via Cozzi 53, I-20125 Milano (Italy); Casella, Francesco, E-mail: francesco2.casella@mail.polimi.it [Politecnico di Milano, Department of Energy, via Lambruschini 4A, I-20156 Milano (Italy)

2017-01-15

Highlights: • Experimental research to measure the efficiency of high-pressure sprays in capturing aerosols if applied to a filtered containment venting system in case of severe accident. • Cloud of monodispersed SiO{sub 2} particles with sizes 0.5 or 1.0 μm and initial concentration in the range 2–90 mg/m{sup 3}. • Carried out in a chamber 0.5 × 1.0 m and 1.5 m high, with transparent walls equipped with a high pressure water spray with single nozzle. • Respect to low-pressure sprays, removal efficiency turned out significant: the half-life for 1 μm particles with a removal high-pressure spray system is orders of magnitude shorter than that with a low-pressure sprays system. - Abstract: An experimental research was managed in the framework of the PASSAM European Project to measure the efficiency of high-pressure sprays in capturing aerosols when applied to a filtered containment venting system in case of severe accident. The campaign was carried out in a purposely built facility composed by a scrubbing chamber 0.5 × 1.0 m and 1.5 m high, with transparent walls to permit the complete view of the aerosol removal process, where the aerosol was injected to form a cloud of specific particle concentration. The chamber was equipped with a high pressure water spray system with a single nozzle placed on its top. The test matrix consisted in the combination of water pressure injections, in the range 50–130 bar, on a cloud of monodispersed SiO{sub 2} particles with sizes 0.5 or 1.0 μm and initial concentration ranging between 2 and 99 mg/m{sup 3}. The spray was kept running for 2 min and the efficiency of the removal was evaluated, along the test time, using an optical particle sizer. With respect to low-pressure sprays, the removal efficiency turned out much more significant: the half-life for 1 μm particles with a removal high-pressure spray system is orders of magnitude shorter than that with a low-pressure spray system. The highest removal rate was

Experiments on aerosol removal by high-pressure water spray

International Nuclear Information System (INIS)

Corno, Ada del; Morandi, Sonia; Parozzi, Flavio; Araneo, Lucio; Casella, Francesco

2017-01-01

Highlights: • Experimental research to measure the efficiency of high-pressure sprays in capturing aerosols if applied to a filtered containment venting system in case of severe accident. • Cloud of monodispersed SiO_2 particles with sizes 0.5 or 1.0 μm and initial concentration in the range 2–90 mg/m"3. • Carried out in a chamber 0.5 × 1.0 m and 1.5 m high, with transparent walls equipped with a high pressure water spray with single nozzle. • Respect to low-pressure sprays, removal efficiency turned out significant: the half-life for 1 μm particles with a removal high-pressure spray system is orders of magnitude shorter than that with a low-pressure sprays system. - Abstract: An experimental research was managed in the framework of the PASSAM European Project to measure the efficiency of high-pressure sprays in capturing aerosols when applied to a filtered containment venting system in case of severe accident. The campaign was carried out in a purposely built facility composed by a scrubbing chamber 0.5 × 1.0 m and 1.5 m high, with transparent walls to permit the complete view of the aerosol removal process, where the aerosol was injected to form a cloud of specific particle concentration. The chamber was equipped with a high pressure water spray system with a single nozzle placed on its top. The test matrix consisted in the combination of water pressure injections, in the range 50–130 bar, on a cloud of monodispersed SiO_2 particles with sizes 0.5 or 1.0 μm and initial concentration ranging between 2 and 99 mg/m"3. The spray was kept running for 2 min and the efficiency of the removal was evaluated, along the test time, using an optical particle sizer. With respect to low-pressure sprays, the removal efficiency turned out much more significant: the half-life for 1 μm particles with a removal high-pressure spray system is orders of magnitude shorter than that with a low-pressure spray system. The highest removal rate was detected with 1 �

Stainless steel coatings produced through atmospheric plasma spraying study of in flight powder behavior and coating structure

International Nuclear Information System (INIS)

Denoirjean, A.; Denoirjean, P.; Fauchais, P.; Labbe, J.C.; Khan, A.A.

2005-01-01

The Stainless Steel coatings deposited through Atmospheric Plasma Spraying over mild steel surface present an interest from commercial point of view, especially for the applications where corrosion resistance or inertness towards severe environment is required. Atmospheric Plasma Spraying is fast and relatively less expensive choice as compared to Vacuum Plasma Spraying, the only limitation being the extremely reactive nature of metallic powders used. A study of the behaviour of metallic powders within an Atmospheric Plasma Jet is presented in view of better understanding and eventual improvement in coating properties. Metallic powder particles show very interesting features when individual particles are collected after passing them through a DC Blown Arc Thermal Plasma Jet under Atmospheric Pressure. The spraying was carried out under air which makes the significance of these results even more interesting from the industrial point of view. Proper control of Spraying Parameters can help produce Stainless Steel coatings of reasonably low porosity and a typical lamellar microstructure. The results of SEM, AFM and XRD are discussed. A strange oxidation phenomenon under highly non equilibrium conditions is observed. (author)

Atmospheric-pressure plasma technology

International Nuclear Information System (INIS)

Kogelschatz, U

2004-01-01

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

A study on the particle melting by plasma spraying

International Nuclear Information System (INIS)

Jung, In Ha; Ji, C. G.; Bae, S. O.; Yoon, J. H.; Kwon, H. I.

2001-12-01

As a preliminary study for fabricating a thick and dense free standing type deposit, powder melting studies were carried out. Various morphologies and sizes of powder having the same chemical compositions were applied in particle melting experiments with varying systematic parameters. Through the study of powder melting by inductively coupled plasma, we can conclude as followings: Argon-hydrogen plasma gas with a higher plasma power gave good quality of splats and shown a higher density with a higher build-up rate. Reproducibility of the experiments appeared in the range of 99%. Degree of particle melting and its density just before impinging played a predominant role in the density of a deposit. Chamber pressure has an effect on degree of deformation of the splats, i.e. on the particle momentum. Completely melted particle showed a high deformation appearance. Build-up rate had a relation with a fraction of the fully melted particle, and this also closely associates with productivity and economical efficiency. For increasing the fraction of the fully melted particle, either increasing the power or limiting the particle size was recommended. Mean pore size and its distribution of a deposit seemed to have a relation with a viscosity of the melted powder, i.e. particle temperature, and also with a chamber pressure and spraying distances. Particle temperature may be governed by a plasma power, plasma gas property, probe position, and spraying distance in the present experimental range. Some results might be appeared with mutual interactions of the effects, for example, particle residence time and momentum with chamber pressure, particle temperature with chamber pressure, spraying distance and its size

A study on the particle melting by plasma spraying

Energy Technology Data Exchange (ETDEWEB)

Jung, In Ha; Ji, C. G.; Bae, S. O.; Yoon, J. H.; Kwon, H. I

2001-12-01

As a preliminary study for fabricating a thick and dense free standing type deposit, powder melting studies were carried out. Various morphologies and sizes of powder having the same chemical compositions were applied in particle melting experiments with varying systematic parameters. Through the study of powder melting by inductively coupled plasma, we can conclude as followings: Argon-hydrogen plasma gas with a higher plasma power gave good quality of splats and shown a higher density with a higher build-up rate. Reproducibility of the experiments appeared in the range of 99%. Degree of particle melting and its density just before impinging played a predominant role in the density of a deposit. Chamber pressure has an effect on degree of deformation of the splats, i.e. on the particle momentum. Completely melted particle showed a high deformation appearance. Build-up rate had a relation with a fraction of the fully melted particle, and this also closely associates with productivity and economical efficiency. For increasing the fraction of the fully melted particle, either increasing the power or limiting the particle size was recommended. Mean pore size and its distribution of a deposit seemed to have a relation with a viscosity of the melted powder, i.e. particle temperature, and also with a chamber pressure and spraying distances. Particle temperature may be governed by a plasma power, plasma gas property, probe position, and spraying distance in the present experimental range. Some results might be appeared with mutual interactions of the effects, for example, particle residence time and momentum with chamber pressure, particle temperature with chamber pressure, spraying distance and its size.

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.

Computer simulation of ZrO2 + 8 % Y2O3 and Al2O3 powder particles heating under plasma spraying

International Nuclear Information System (INIS)

Smurov, I.; Gusarov, A.; Hurevich, V.; Kundas, S.; Kashko, T.

2001-01-01

The optimization of plasma spraying processes and investigation of the influence of different parameters and variables on particle trajectories, final temperature distributions and velocities were the aim of this study. A mathematical model for simulation of powder particle heating and acceleration in a plasma jet with particle evaporation and diameter reduction is developed. The choice of the evaporation model strongly depends on the pressure of surrounded gas, for low and atmospheric pressures models were developed. A software with a database for material properties was developed, the first allows to conduct simulation of plasma spraying and contains several models for simulating the different stages of plasma spraying, providing a common interface and access to the database for all the models. The input or output data can be represented as ordinary graphic, distributed diagram or by special way, i.e. animation of particle moving and heating in plasma jet, diagram of phase changing etc. By using this program the process of stabilized zirconium oxide and aluminium oxide coating plasma spraying was simulated. (nevyjel)

Development & characterization of alumina coating by atmospheric plasma spraying

Science.gov (United States)

Sebastian, Jobin; Scaria, Abyson; Kurian, Don George

2018-03-01

Ceramic coatings are applied on metals to prevent them from oxidation and corrosion at room as well as elevated temperatures. The service environment, mechanisms of protection, chemical and mechanical compatibility, application method, control of coating quality and ability of the coating to be repaired are the factors that need to be considered while selecting the required coating. The coatings based on oxide materials provides high degree of thermal insulation and protection against oxidation at high temperatures for the underlying substrate materials. These coatings are usually applied by the flame or plasma spraying methods. The surface cleanliness needs to be ensured before spraying. Abrasive blasting can be used to provide the required surface roughness for good adhesion between the substrate and the coating. A pre bond coat like Nickel Chromium can be applied on to the substrate material before spraying the oxide coating to avoid chances of poor adhesion between the oxide coating and the metallic substrate. Plasma spraying produces oxide coatings of greater density, higher hardness, and smooth surface finish than that of the flame spraying process Inert gas is often used for generation of plasma gas so as to avoid the oxidation of the substrate material. The work focuses to develop, characterize and optimize the parameters used in Al2O3 coating on transition stainless steel substrate material for minimizing the wear rate and maximizing the leak tightness using plasma spray process. The experiment is designed using Taguchi’s L9 orthogonal array. The parameters that are to be optimized are plasma voltage, spraying distance and the cooling jet pressure. The characterization techniques includes micro-hardness and porosity tests followed by Grey relational analysis of the results.

Analytical interpretation of arc instabilities in a DC plasma spray torch: the role of pressure

Science.gov (United States)

Rat, V.; Coudert, J. F.

2016-06-01

Arc instabilities in a plasma spray torch are investigated experimentally and theoretically thanks to a linear simplified analytical model. The different parameters that determine the useful properties of the plasma jet at the torch exit, such as specific enthalpy and speed, but also pressure inside the torch and time variations of the flow rate are studied. The work is particularly focused on the link between the recorded arc voltage and the pressure in the cathode cavity. A frequency analysis of the recorded voltage and pressure allows the separation of different contributions following their spectral characteristics and highlights a resonance effect due to Helmholtz oscillations; these oscillations are responsible for the large amplitude fluctuations of all the parameters investigated. The influence of heat transfer, friction forces and residence time of the plasma in the nozzle are taken into account, thanks to different characteristics’ times. The volume of the cathode cavity in which the cold gas is stored before entering the arc region appears to be of prime importance for the dynamics of instabilities, particularly for the non-intuitive effect that induces flow-rate fluctuations in spite of the fact that the torch is fed at a constant flow rate.

Behavior of porous beryllium under thermomechanical loading. Part 6. Effect of pressure on the microstructure of plasma-sprayed beryllium

International Nuclear Information System (INIS)

Hanafee, J.E.; Snell, E.O.

1975-01-01

The effects of pressure and specimen preparation on the microstructure of two grades of porous plasma-sprayed beryllium were determined. One grade, P-1, was sintered after spraying while the other grade, P-10, was tested in the as-sprayed condition. the principal microstructural characteristics studied were grain size: grain morphology, and void distribution and size. It was found that machining can readily cause a significant dense surface layer on the porous beryllium specimens, and that the dense surface layer can be removed by etching. There was substantial difference in microstructure between the P-1 sintered and P-10 unsintered specimens both before and after being subjected to shock waves and static compression. (U.S.)

High-beta plasma effects in a low-pressure helicon plasma

International Nuclear Information System (INIS)

Corr, C. S.; Boswell, R. W.

2007-01-01

In this work, high-beta plasma effects are investigated in a low-pressure helicon plasma source attached to a large volume diffusion chamber. When operating above an input power of 900 W and a magnetic field of 30 G a narrow column of bright blue light (due to Ar II radiation) is observed along the axis of the diffusion chamber. With this blue mode, the plasma density is axially very uniform in the diffusion chamber; however, the radial profiles are not, suggesting that a large diamagnetic current might be induced. The diamagnetic behavior of the plasma has been investigated by measuring the temporal evolution of the magnetic field (B z ) and the plasma kinetic pressure when operating in a pulsed discharge mode. It is found that although the electron pressure can exceed the magnetic field pressure by a factor of 2, a complete expulsion of the magnetic field from the plasma interior is not observed. In fact, under our operating conditions with magnetized ions, the maximum diamagnetism observed is ∼2%. It is observed that the magnetic field displays the strongest change at the plasma centre, which corresponds to the maximum in the plasma kinetic pressure. These results suggest that the magnetic field diffuses into the plasma sufficiently quickly that on a long time scale only a slight perturbation of the magnetic field is ever observed

Experimental Verification of Statistically Optimized Parameters for Low-Pressure Cold Spray Coating of Titanium

Directory of Open Access Journals (Sweden)

Damilola Isaac Adebiyi

2016-06-01

Full Text Available The cold spray coating process involves many process parameters which make the process very complex, and highly dependent and sensitive to small changes in these parameters. This results in a small operational window of the parameters. Consequently, mathematical optimization of the process parameters is key, not only to achieving deposition but also improving the coating quality. This study focuses on the mathematical identification and experimental justification of the optimum process parameters for cold spray coating of titanium alloy with silicon carbide (SiC. The continuity, momentum and the energy equations governing the flow through the low-pressure cold spray nozzle were solved by introducing a constitutive equation to close the system. This was used to calculate the critical velocity for the deposition of SiC. In order to determine the input temperature that yields the calculated velocity, the distribution of velocity, temperature, and pressure in the cold spray nozzle were analyzed, and the exit values were predicted using the meshing tool of Solidworks. Coatings fabricated using the optimized parameters and some non-optimized parameters are compared. The coating of the CFD-optimized parameters yielded lower porosity and higher hardness.

Non-equilbrium behavior of low-pressure plasma jets

International Nuclear Information System (INIS)

Chang, C.H.; Pfender, E.

1989-01-01

After establishing the basic equations, some sample calculations are presented to examine the thermodynamic state of the plasma from atmospheric to low pressures (80 mbar). These results indicate the validity of local thermodynamic equilibrium (LTE) at atmospheric pressure as well as strong deviations from LTE at lower pressures especially in terms of chemical equilibrium. Departures from kinetic equilibrium are not as severe as those from chemical equilibrium along the centerline of the jet. However, there are some departures from transitional equilibrium in the fringes of the jet. It is demonstrated that conventional methods based on the LTE assumption are not appropriate for describing low-pressure plasma jets

Determine spray droplets on water sensitive paper (WSP) for low pressure deflector nozzle using image J

Science.gov (United States)

Sies, M. F.; Madzlan, N. F.; Asmuin, N.; Sadikin, A.; Zakaria, H.

2017-09-01

In this study, determine of spray droplets size (SMD) using water sensitive paper (WSP) at low fluid pressure with deflector nozzle or tangential flow nozzle model Delavan AL75 and New Design Nozzle with two different type of swirl (ND2.5 A1.0 & ND2.5 B1.0). These three deflected flat sprays have used at different liquid mixing ratio. These liquid mixture ratios are pure water, 10% of lime juice + 90% of water (L10W90) and 30% of lime juice + 70% of water (L30W70). WSP is used to collect the spray droplets from nozzles. The operational liquid pressure of each nozzle is 3 bar, while air operational pressures are 3 bar and 6 bar. Then, the WSP were scanned using scanner then it was analyzed using ImageJ software. ImageJ can be used for determining the diameter of droplets size on the WSP. As the results from an experiment, the AL75 nozzle recorded the lowest Sauter mean diameter which is 193.69μm at 6 bar of pressurized air while ND2.5 A1.0 recorded the highest Sauter mean diameter which is 353.61µm at 3 bar of pressurized air. Summary from the experiment shows that the higher of droplet size is because of the lower air pressure (3 Bar). Then, increasing of liquid viscosity also increase the SMD. The orifice diameter for New Design nozzle (ND-2.5) is smaller than AL75, which are 2.5mm and 2.8mm respectively. The different nozzle design also gives effect the SMD. WSP is an alternative method to determine SMD for spray droplets with the low cost if compared to Phase Doppler Anemometry (PDA).

Plasma spraying process of disperse carbides for spraying and facing

International Nuclear Information System (INIS)

Blinkov, I.V.; Vishnevetskaya, I.A.; Kostyukovich, T.G.; Ostapovich, A.O.

1989-01-01

A possibility to metallize carbides in plasma of impulsing capacitor discharge is considered. Powders granulation occurs during plasma spraying process, ceramic core being completely capped. X-ray phase and chemical analyses of coatings did not show considerable changes of carbon content in carbides before and after plasma processing. This distinguishes the process of carbides metallization in impulsing plasma from the similar processing in arc and high-frequency plasma generator. Use of powder composites produced in the impulsing capacitor discharge, for plasma spraying and laser facing permits 2-3 times increasing wear resistance of the surface layer as against the coatings produced from mechanical powders mixtures

X-ray structural analysis of plasma sprayed europium oxide

Energy Technology Data Exchange (ETDEWEB)

Gorshkov, B.N.; Loskutov, V.S.; Gavrish, A.A.; Shakh, G.E.

1981-12-01

An X-ray structure microanalysis is made for europium oxide powder produced by sintering and plasmic spheroidization for plasma spraying. The technique of concern is shown not to alter chemical composition of the powder. It is stated that a rise in the plasma jet enthalpy while spraying does not result in dissociation of europium oxide and its interaction with the plasma flux. The coating (to 15.2 kWxs/g) is found to have only a high-temperature (monoclinic) europium oxide phase and there appears a low-temperature (cubic) phase with a subsequent increase in the enthalpy. The plasma jet enthalpy increasing the grain size and the crystal lattice c parameter of the sprayed europium oxide are shown to decrease; the a parameter reduces with an enthalpy growth to 16.2 kW s/g and then smoothly increases with the enthalpy further growth. It is noticed that the europium oxide coating does not interact with an aluminium D16 alloy substrate.

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.

Investigating Tribological Characteristics of HVOF Sprayed AISI 316 Stainless Steel Coating by Pulsed Plasma Nitriding

Science.gov (United States)

Mindivan, H.

2018-01-01

In this study, surface modification of aluminum alloy using High-Velocity Oxygen Fuel (HVOF) thermal spray and pulsed plasma nitriding processes was investigated. AISI 316 stainless steel coating on 1050 aluminum alloy substrate by HVOF process was pulsed plasma nitrided at 793 K under 0.00025 MPa pressure for 43200 s in a gas mixture of 75 % N2 and 25 % H2. The results showed that the pulse plasma nitriding process produced a surface layer with CrN, iron nitrides (Fe3N, Fe4N) and expanded austenite (γN). The pulsed plasma nitrided HVOF-sprayed coating showed higher surface hardness, lower wear rate and coefficient of friction than the untreated HVOF-sprayed one.

Head spray nozzle in reactor pressure vessel

International Nuclear Information System (INIS)

Hatano, Shun-ichi.

1990-01-01

In a reactor pressure vessel of a BWR type reactor, a head spray nozzle is used for cooling the head of the pressure vessel and, in view of the thermal stresses, it is desirable that cooling is applied as uniformly as possible. A conventional head spray is constituted by combining full cone type nozzles. Since the sprayed water is flown down upon water spraying and the sprayed water in the vertical direction is overlapped, the flow rate distribution has a high sharpness to form a shape as having a maximum value near the center and it is difficult to obtain a uniform flow rate distribution in the circumferential direction. Then, in the present invention, flat nozzles each having a spray water cross section of laterally long shape, having less sharpness in the circumferential distribution upon spraying water to the inner wall of the pressure vessel and having a wide angle of water spray are combined, to make the flow rate distribution of spray water uniform in the inner wall of the pressure vessel. Accordingly, the pressure vessel can be cooled uniformly and thermal stresses upon cooling can be decreased. (N.H.)

Ultrasonic technique for measuring porosity of plasma-sprayed alumina coatings

Science.gov (United States)

Parthasarathi, S.; Tittmann, B. R.; Onesto, E. J.

1997-12-01

Porosity is an important factor in plasma-sprayed coatings, especially ceramic coatings. Excessive poros-ity can adversely affect the performance of the coated component in various ways. An ultrasonic nonde-structive measurement technique has been developed to measure porosity in plasma-sprayed alumina coatings. The technique is generic and can be extended to other ceramic coating systems. To test the tech-nique, freestanding alumina coatings with varying levels of porosity were fabricated via plasma spray. Samples with varying porosity, obtained through innovative fabrication techniques, were used to gener-ate a calibration curve. The ultrasonic velocity in the low-frequency range was found to be dependent on the density of freestanding coatings (measured via Archimedian techniques). This dependence is the basis of the development of a technique to measure the density of coatings.

Plasma sprayed samarium--cobalt permanent magnets

International Nuclear Information System (INIS)

Willson, M.C.; Janowiecki, R.J.

1975-01-01

Samarium--cobalt permanent magnets were fabricated by arc plasma spraying. This process involves the injection of relatively coarse powder particles into a high-temperature gas for melting and spraying onto a substrate. The technique is being investigated as an economical method for fabricating cobalt--rare earth magnets for advanced traveling wave tubes and cross-field amplifiers. Plasma spraying permits deposition of material at high rates over large areas with optional direct bonding to the substrate, and offers the ability to fabricate magnets in a variety of shapes and sizes. Isotropic magnets were produced with high coercivity and good reproducibility in magnetic properties. Post-spray thermal treatments were used to enhance the magnetic properties of sprayed deposits. Samarium--cobalt magnets, sprayed from samarium-rich powder and subjected to post-spray heat treatment, displayed energy products in excess of 9 million gauss-oersteds and coercive forces of approximately 6000 oersteds. Bar magnet arrays were constructed by depositing magnets on ceramic substrates. (auth)

Plasma sprayed samarium--cobalt permanent magnets

International Nuclear Information System (INIS)

Willson, M.C.; Janowiecki, R.J.

1975-01-01

Samarium--Co permanent magnets were fabricated by arc plasma spraying. This process involves the injection of relatively coarse powder particles into a high temperature gas for melting and spraying onto a substrate. The technique is being investigated as an economical method for fabricating Co--rare earth magnets for advanced traveling wave tubes and cross-field amplifiers. Plasma spraying permits deposition of material at high rates over large areas with optional direct bonding to the substrate, and offers the ability to fabricate magnets in a variety of shapes and sizes. Isotropic magnets were produced with high coercivity and good reproducibility in magnetic properties. Post-spray thermal treatments were used to enhance the magnetic properties of sprayed deposits. Samarium--Co magnets, sprayed from Sm-rich powder and subjected to post-spray heat treatment, displayed energy products in excess of 9 million G-Oe and coercive forces of approximately 6000 Oe. Bar magnet arrays were constructed by depositing magnets on ceramic substrates

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.

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.

Plasma spraying of beryllium and beryllium-aluminum-silver alloys

International Nuclear Information System (INIS)

Castro, R.G.; Stanek, P.W.; Elliott, K.E.; Jacobson, L.A.

1994-01-01

A preliminary investigation on plasma-spraying of beryllium and a beryllium-aluminum-4% silver alloy was done at the Los Alamos National Laboratory's Beryllium Atomization and Thermal Spray Facility (BATSF). Spherical Be and Be-Al-4%Ag powders, which were produced by centrifugal atomization, were used as feedstock material for plasma-spraying. The spherical morphology of the powders allowed for better feeding of fine (<38 μm) powders into the plasma-spray torch. The difference in the as-deposited densities and deposit efficiencies of the two plasma-sprayed powders will be discussed along with the effect of processing parameters on the as-deposited microstructure of the Be-Al-4%Ag. This investigation represents ongoing research to develop and characterize plasma-spraying of beryllium and beryllium-aluminum alloys for magnetic fusion and aerospace applications

Plasma spraying of beryllium and beryllium-aluminum-silver alloys

International Nuclear Information System (INIS)

Castro, R.G.; Stanek, P.W.; Elliott, K.E.; Jacobson, L.A.

1993-01-01

A preliminary investigation on plasma-spraying of beryllium and a beryllium-aluminum 4% silver alloy was done at the Los Alamos National Laboratory's Beryllium Atomization and Thermal Spray Facility (BATSF). Spherical Be and Be-Al-4%Ag powders, which were produced by centrifugal atomization, were used as feedstock material for plasma-spraying. The spherical morphology of the powders allowed for better feeding of fine (<38 μm) powders into the plasma-spray torch. The difference in the as-deposited densities and deposit efficiencies of the two plasma-sprayed powders will be discussed along with the effect of processing parameters on the as-deposited microstructure of the Be-Al-4%Ag. This investigation represents ongoing research to develop and characterize plasma-spraying of beryllium and beryllium-aluminum alloys for magnetic fusion and aerospace applications

Nanostructure of plasma-sprayed hydroxyapatite coating

International Nuclear Information System (INIS)

Suvorova, E.I.; Klechkovskaya, V.V.; Bobrovsky, V.V.; Khamchukov, Yu.D.; Klubovich, V.V.

2003-01-01

Calcium phosphate coatings were studied by high-resolution transmission microscopy, microdiffraction, and X-ray energy-dispersive spectroscopy. Coatings were prepared by spraying hydroxyapatite targets onto copper, nickel, and chromium substrates and onto NaCl and BaF 2 single crystals in an argon plasma at a gas pressure of ∼1 Pa; the sputter power was about 200 W; and the RF-generator frequency was 13.56 MHz. Under the conditions used, thin layers of nanocrystalline hydroxyapatite were formed regardless of the nature of the substrate

Plasma spray technology process parameters and applications

International Nuclear Information System (INIS)

Sreekumar, K.P.; Karthikeyan, J.; Ananthapadmanabhan, P.V.; Venkatramani, N.; Chatterjee, U.K.

1991-01-01

The current trend in the structural design philosophy is based on the use of substrate with the necessary mechanical properties and a thin coating to exhibit surface properties. Plasma spray process is a versatile surface coating technique which finds extensive application in meeting advance technologies. This report describes the plasma spray technique and its use in developing coatings for various applications. The spray system is desribed in detail including the different variables such as power input to the torch, gas flow rate, powder properties, powder injection, etc. and their interrelation in deciding the quality of the coating. A brief write-up on the various plasma spray coatings developed for different applications is also included. (author). 15 refs., 15 figs., 2 tabs

Behaviour of plasma spray coatings under disruption simulation

International Nuclear Information System (INIS)

Brossa, F.; Rigon, G.; Looman, B.

1988-01-01

The behaviour of metallic and ceramic protective coatings under disruption simulations was studied correlating the damage with their physical and structural parameters. Plasma Spray (PS) and Vacuum Plasma Spray (VPS) were the techniques used for the production of the coatings. W-5% Re was selected for divertor plates, and TiC, TiO 2 , Al 2 O 3 , low-Z ceramic materials for the first wall protection on 316 SS, Cu and Al as substrates. An electron beam gun was used to simulate the plasma disruptions. The tests were carried out from 0.6 to 6 MJ/m 2 . The thermal effects were studied by metallographic and EDXA analysis. The damage was observed comparing the degree of protection provided by each coating to discover the minimum thickness necessary to prevent the underlying material from melting. Good protective coatings must have a high melting point, great porosity and low thermal conductivity. Such coatings act as thermal barriers, increasing the surface temperature and radiating back large parts of the energy. (orig.)

Plasma sprayed and electrospark deposited zirconium metal diffusion barrier coatings

International Nuclear Information System (INIS)

Hollis, Kendall J.; Pena, Maria I.

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.

Design and experiment of high-current low-pressure plasma-cathode e-gun

International Nuclear Information System (INIS)

Xie Wenkai; Li Xiaoyun; Wang Bin; Meng Lin; Yan Yang; Gao Xinyan

2006-01-01

The preliminary design of a new high-power low pressure plasma-cathode e-gun is presented. Based on the hollow cathode effect and low-pressure glow discharge empirical formulas, the hollow cathode, the accelerating gap, and the working gas pressure region are given. The general experimental device of the low-pressure plasma cathode electron-gun generating high current density e-beam source is shown. Experiments has been done in continuous filled-in gases and gases-puff condition, and the discharging current of 150-200 A, the width of 60 μs and the collector current of 30-80 A, the width of 60 μs are obtained. The results show that the new plasma cathode e-gun can take the place of material cathode e-gun, especially in plasma filled microwave tubes. (authors)

Hydrogen permeation properties of plasma-sprayed tungsten

International Nuclear Information System (INIS)

Anderl, R.A.; Pawelko, R.J.; Hankins, M.R.; Longhurst, G.R.; Neiser, R.A.

1994-01-01

Tungsten has been proposed as a plasma-facing component material for advanced fusion facilities. This paper reports on laboratory-scale studies that were done to assess the hydrogen permeation properties of plasma-sprayed tungsten for such applications. The work entailed deuterium permeation measurements for plasma-sprayed (PS) tungsten coatings, sputter-deposited (SP) tungsten coatings, and steel substrate material using a mass-analyzed, 3 keV D + 3 ion beam with fluxes of similar 6.5x10 19 D/m 2 s. Extensive characterization analyses for the plasma-sprayed tungsten coatings were made using Auger spectrometry and scanning electron microscopy (SEM). Observed permeation rates through composite PS-tungsten/steel specimens were several orders of magnitude below the permeation levels observed for SP-tungsten/steel composite specimens and pure steel specimens. Characterization analyses indicated that the plasma-sprayed tungsten coating had a nonhomogeneous microstructure that consisted of splats with columnar solidification, partially-melted particles with grain boundaries, and void regions. Reduced permeation levels can be attributed to the complex microstructure and a substantial surface-connected porosity. ((orig.))

Hydrogen permeation properties of plasma-sprayed tungsten

Energy Technology Data Exchange (ETDEWEB)

Anderl, R.A. (Idaho National Engineering Lab., EG and G Idaho Inc., Idaho Falls, ID (United States)); Pawelko, R.J. (Idaho National Engineering Lab., EG and G Idaho Inc., Idaho Falls, ID (United States)); Hankins, M.R. (Idaho National Engineering Lab., EG and G Idaho Inc., Idaho Falls, ID (United States)); Longhurst, G.R. (Idaho National Engineering Lab., EG and G Idaho Inc., Idaho Falls, ID (United States)); Neiser, R.A. (Sandia National Laboratories, Albuquerque, NM 87185 (United States))

1994-09-01

Tungsten has been proposed as a plasma-facing component material for advanced fusion facilities. This paper reports on laboratory-scale studies that were done to assess the hydrogen permeation properties of plasma-sprayed tungsten for such applications. The work entailed deuterium permeation measurements for plasma-sprayed (PS) tungsten coatings, sputter-deposited (SP) tungsten coatings, and steel substrate material using a mass-analyzed, 3 keV D[sup +][sub 3] ion beam with fluxes of similar 6.5x10[sup 19] D/m[sup 2] s. Extensive characterization analyses for the plasma-sprayed tungsten coatings were made using Auger spectrometry and scanning electron microscopy (SEM). Observed permeation rates through composite PS-tungsten/steel specimens were several orders of magnitude below the permeation levels observed for SP-tungsten/steel composite specimens and pure steel specimens. Characterization analyses indicated that the plasma-sprayed tungsten coating had a nonhomogeneous microstructure that consisted of splats with columnar solidification, partially-melted particles with grain boundaries, and void regions. Reduced permeation levels can be attributed to the complex microstructure and a substantial surface-connected porosity. ((orig.))

Automated Plasma Spray (APS) process feasibility study: Plasma spray process development and evaluation

Science.gov (United States)

Fetheroff, C. W.; Derkacs, T.; Matay, I. M.

1979-01-01

An automated plasma spray (APS) process was developed to apply two layer (NiCrAlY and ZrO2-12Y2O3) thermal-barrier coatings to aircraft gas turbine engine blade airfoils. The APS process hardware consists of four subsystems: a mechanical blade positioner incorporating two interlaced six-degree-of-freedom assemblies; a noncoherent optical metrology subsystem; a microprocessor-based adaptive system controller; and commercial plasma spray equipment. Over fifty JT9D first stage turbine blades specimens were coated with the APS process in preliminary checkout and evaluation studies. The best of the preliminary specimens achieved an overall coating thickness uniformity of + or - 53 micrometers, much better than is achievable manually. Factors limiting this performance were identified and process modifications were initiated accordingly. Comparative evaluations of coating thickness uniformity for manually sprayed and APS coated specimens were initiated. One of the preliminary evaluation specimens was subjected to a torch test and metallographic evaluation.

Molybdenum disilicide composites produced by plasma spraying

International Nuclear Information System (INIS)

Castro, R.G.; Hollis, K.J.; Kung, H.H.; Bartlett, A.H.

1998-01-01

The intermetallic compound, molybdenum disilicide (MoSi 2 ) is being considered for high temperature structural applications because of its high melting point and superior oxidation resistance at elevated temperatures. The lack of high temperature strength, creep resistance and low temperature ductility has hindered its progress for structural applications. Plasma spraying of coatings and structural components of MoSi 2 -based composites offers an exciting processing alternative to conventional powder processing methods due to superior flexibility and the ability to tailor properties. Laminate, discontinuous and in situ reinforced composites have been produced with secondary reinforcements of Ta, Al 2 O 3 , SiC, Si 3 N 4 and Mo 5 Si 3 . Laminate composites, in particular, have been shown to improve the damage tolerance of MoSi 2 during high temperature melting operations. A review of research which as been performed at Los Alamos National Laboratory on plasma spraying of MoSi 2 -based composites to improve low temperature fracture toughness, thermal shock resistance, high temperature strength and creep resistance will be discussed

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.

Hydrogen permeation properties of plasma-sprayed tungsten*1

Science.gov (United States)

Anderl, R. A.; Pawelko, R. J.; Hankins, M. R.; Longhurst, G. R.; Neiser, R. A.

1994-09-01

Tungsten has been proposed as a plasma-facing component material for advanced fusion facilities. This paper reports on laboratory-scale studies that were done to assess the hydrogen permeation properties of plasma-sprayed tungsten for such applications. The work entailed deuterium permeation measurements for plasma-sprayed (PS) tungsten coatings, sputter-deposited (SP) tungsten coatings, and steel substrate material using a mass-analyzed, 3 keV D 3+ ion beam with fluxes of ˜6.5 × 10 19 D/m 2 s. Extensive characterization analyses for the plasma-sprayed tungsten coatings were made using Auger spectrometry and scanning electron microscopy (SEM). Observed permeation rates through composite PS-tungsten/steel specimens were several orders of magnitude below the permeation levels observed for SP-tungsten/steel composite specimens and pure steel specimens. Characterization analyses indicated that the plasma-sprayed tungsten coating had a nonhomogeneous microstructure that consisted of splats with columnar solidification, partially-melted particles with grain boundaries, and void regions. Reduced permeation levels can be attributed to the complex microstructure and a substantial surface-connected porosity.

Investigation of spray characteristics from a low-pressure common rail injector for use in a homogeneous charge compression ignition engine

Science.gov (United States)

Lee, Kihyung; Reitz, Rolf D.

2004-03-01

Homogeneous charge compression ignition (HCCI) combustion provides extremely low levels of pollutant emissions, and thus is an attractive alternative for future IC engines. In order to achieve a uniform mixture distribution within the engine cylinder, the characteristics of the fuel spray play an important role in the HCCI engine concept. It is well known that high-pressure common rail injection systems, mainly used in diesel engines, achieve poor mixture formation because of the possibility of direct fuel impingement on the combustion chamber surfaces. This paper describes spray characteristics of a low-pressure common rail injector which is intended for use in an HCCI engine. Optical diagnostics including laser diffraction and phase Doppler methods, and high-speed camera photography, were applied to measure the spray drop diameter and to investigate the spray development process. The drop sizing results of the laser diffraction method were compared with those of a phase Doppler particle analyser (PDPA) to validate the accuracy of the experiments. In addition, the effect of fuel properties on the spray characteristics was investigated using n-heptane, Stoddard solvent (gasoline surrogate) and diesel fuel because HCCI combustion is sensitive to the fuel composition. The results show that the injector forms a hollow-cone sheet spray rather than a liquid jet, and the atomization efficiency is high (small droplets are produced). The droplet SMD ranged from 15 to 30 µm. The spray break-up characteristics were found to depend on the fuel properties. The break-up time for n-heptane is shorter and the drop SMD is smaller than that of Stoddard solvent and diesel fuel.

dc-plasma-sprayed electronic-tube device

Science.gov (United States)

Meek, T.T.

1982-01-29

An electronic tube and associated circuitry which is produced by dc plasma arc spraying techniques is described. The process is carried out in a single step automated process whereby both active and passive devices are produced at very low cost. The circuitry is extremely reliable and is capable of functioning in both high radiation and high temperature environments. The size of the electronic tubes produced are more than an order of magnitude smaller than conventional electronic tubes.

The effect of processing parameters on plasma sprayed beryllium for fusion applications

International Nuclear Information System (INIS)

Castro, R.G.; Stanek, P.W.; Jacobson, L.A.; Cowgill, D.F.; Snead, L.L.

1993-01-01

Plasma spraying is being investigated as a potential coating technique for applying thin (0.1--5mm) layers of beryllium on plasma facing surfaces of blanket modules in ITER and also as an in-situ repair technique for repairing eroded beryllium surfaces in high heat flux divertor regions. High density spray deposits (>98% of theoretical density) of beryllium will be required in order to maximize the thermal conductivity of the beryllium coatings. A preliminary investigation was done to determine the effect of various processing parameters (particle size, particle morphology, secondary gas additions and reduced chamber pressure) on the as-deposited density of beryllium. The deposits were made using spherical beryllium feedstock powder which was produced by centrifugal atomization at Los Alamos National Laboratory (LANL). Improvements in the as-deposited densities and deposit efficiencies of the beryllium spray deposits will be discussed along with the corresponding thermal conductivity and outgassing behavior of these deposits

The effect of processing parameters on plasma sprayed beryllium for fusion applications

International Nuclear Information System (INIS)

Castro, R.G.; Stanek, P.W.; Jacobson, L.W.; Cowgill, D.F.

1993-01-01

Plasma spraying is being investigated as a potential coating technique for applying thin (0.1-5mm) layers of beryllium on plasma facing surfaces of blanket modules in ITER and also as an in-situ repair technique for repairing eroded beryllium surfaces in high heat flux divertor regions. High density spray deposits (>98% of theoretical density) of beryllium will be required in order to maximize the thermal conductivity of the beryllium coatings. A preliminary investigation was done to determine the effect of various processing parameters (particle size, particle morphology, secondary gas additions and reduced chamber pressure) on the as-deposited density of beryllium. The deposits were made using spherical beryllium feedstock powder which was produced by centrifugal atomization at Los Alamos National Laboratory (LANL). Improvements in the as-deposited densities and deposit efficiencies of the beryllium spray deposits will be discussed along with the corresponding thermal conductivity and outgassing behavior of these deposits. (orig.)

Generator of the low-temperature heterogeneous plasma flow

Science.gov (United States)

Yusupov, D. I.; Gadzhiev, M. Kh; Tyuftyaev, A. S.; Chinnov, V. F.; Sargsyan, M. A.

2018-01-01

A generator of low-temperature dc plasma with an expanding channel of an output electrode for gas-thermal spraying was designed and constructed. The delivery of the sprayed powder into the cathode and anode arc-binding zones or into the plasma jet below the anode binding was realized. The electrophysical characteristics of both the plasma torch and the heterogeneous plasma flow with Al2O3 powder are studied. It is shown that the current-voltage characteristic (CVC) of a plasma torch depends on the gas flow rate. If the flow rate varies from 1 to 3 g/s, the falling CVC becomes gradually increasing. The speed and temperature of the sprayed powder are determined.

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 OBOR OECD: Coating and films Impact factor: 1.488, year: 2016 http://link.springer.com/article/10.1007/s11666-016-0493-6

Alignment Fixtures For Vacuum-Plasma-Spray Gun

Science.gov (United States)

Woodford, William H.; Mckechnie, Timothy N.; Power, Christopher A.; Daniel, Ronald L., Jr.

1993-01-01

Fixtures for alignment of vacuum-plasma-spray guns built. Each fixture designed to fit specific gun and holds small, battery-powered laser on centerline of gun. Laser beam projects small red dot where centerline intersects surface of workpiece to be sprayed. After laser beam positioned on surface of workpiece, fixture removed from gun and spraying proceeds.

Model of the macrostructure formation of plasma sprayed coatings

International Nuclear Information System (INIS)

Gnedovets, A.G.; Kalita, V.I.

2007-01-01

A 3D discrete ballistic model of plasma sprayed coatings structure formation is presented. The effect of a spraying angle on porous macrostructure of coatings is investigated by numerical computations.Computer simulation results as well as experimental data show that at a sputtering angle less than 45 deg the mechanism of surface relief formation is changed and the relief consists of valleys and ridges under such conditions of plasma spraying [ru

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.

Plasma sprayed thermoregulating coatings

International Nuclear Information System (INIS)

Kudinov, V.V.; Puzanov, A.A.; Zambrzhitskij, A.P.; Soboleva, V.V.

1979-01-01

Shown is the possibility of plasma spraying application for thermoregulating coating formation. Given are test results of service properties of BeO, Al 2 O 2 plasma coatings on the substrates of the MA2-1 magnesium alloy. Described is a device for studying durability of coating optical parameters under ultraviolet irradiation in deep vacuum. Dynamics of absorption coefficient, growth caused by an increase in absorption centers amount under such irradiation is investigated

Evaluation of Plasma Spray hydroxy Apatite Coatings on Metallic Materials

International Nuclear Information System (INIS)

Take, S.; Mitsul, K.; Kasahara, M.; Sawal, R.; Izawa, S.; Nakayama, M.; Itoi, Y.

2007-01-01

Biocompatible Hydroxy apatite (HAp) coatings on metallic substrate by plasma spray techniques have been developed. Long-term credibility of plasma spray HAp coatings has been evaluated in physiological saline by electrochemical measurements. It was found that the corrosion resistance of SUS316L based HAp/Ti combined coatings was excellent even after more than 10 weeks long-term immersion. It was shown that postal heat treatment improved both the crystallinity and corrosion resistance of HAp. By lowering cooling rate during heat treatment process, less cracks produced in HAp coating layer, which lead to higher credibility of HAp during immersion in physiological saline. The ICP results showed that the dissolution level of substrate metallic ions was low and HAp coatings produced in this research can be acceptable as biocompatible materials. Also, the concentration of dissolved ions from HAp coatings with postal heat treatment was lower compared to those from samples without postal heat treatment. The adherence of HAp coatings with Ti substrate and other mechanical properties were also assessed by three-point bending test. The poor adhesion of HAp coating to titanium substrate can be improved by introducing a plasma spray titanium intermediate layer

Thin films by metal-organic precursor plasma spray

International Nuclear Information System (INIS)

Schulz, Douglas L.; Sailer, Robert A.; Payne, Scott; Leach, James; Molz, Ronald J.

2009-01-01

While most plasma spray routes to coatings utilize solids as the precursor feedstock, metal-organic precursor plasma spray (MOPPS) is an area that the authors have investigated recently as a novel route to thin film materials. Very thin films are possible via MOPPS and the technology offers the possibility of forming graded structures by metering the liquid feed. The current work employs metal-organic compounds that are liquids at standard temperature-pressure conditions. In addition, these complexes contain chemical functionality that allows straightforward thermolytic transformation to targeted phases of interest. Toward that end, aluminum 3,5-heptanedionate (Al(hd) 3 ), triethylsilane (HSi(C 2 H 5 ) 3 or HSiEt 3 ), and titanium tetrakisdiethylamide (Ti(N(C 2 H 5 ) 2 ) 4 or Ti(NEt 2 ) 4 ) were employed as precursors to aluminum oxide, silicon carbide, and titanium nitride, respectively. In all instances, the liquids contain metal-heteroatom bonds envisioned to provide atomic concentrations of the appropriate reagents at the film growth surface, thus promoting phase formation (e.g., Si-C bond in triethylsilane, Ti-N bond in titanium amide, etc.). Films were deposited using a Sulzer Metco TriplexPro-200 plasma spray system under various experimental conditions using design of experiment principles. Film compositions were analyzed by glazing incidence x-ray diffraction and elemental determination by x-ray spectroscopy. MOPPS films from HSiEt 3 showed the formation of SiC phase but Al(hd) 3 -derived films were amorphous. The Ti(NEt 2 ) 4 precursor gave MOPPS films that appear to consist of nanosized splats of TiOCN with spheres of TiO 2 anatase. While all films in this study suffered from poor adhesion, it is anticipated that the use of heated substrates will aid in the formation of dense, adherent films.

Analysis of processes in DC arc plasma torches for spraying that use air as plasma forming gas

International Nuclear Information System (INIS)

Frolov, V; Ivanov, D; Toropchin, A

2014-01-01

Developed in Saint Petersburg State Polytechnical University technological processes of air-plasma spraying of wear-resistant, regenerating, hardening and decorative coatings used in number of industrial areas are described. The article contains examples of applications of air plasma spraying of coatings as well as results of mathematical modelling of processes in air plasma torches for spraying

A study on the macroscopic spray behavior and atomization characteristics of biodiesel and dimethyl ether sprays under increased ambient pressure

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyung Jun; Park, Su Han [Graduate School of Hanyang University, 17 Haengdang-dong, Seoungdong-gu, Seoul 133-791 (Korea); Lee, Chang Sik [Department of Mechanical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea)

2010-03-15

The aim of this work is to investigate the spray behaviors of biodiesel and dimethyl ether (DME) fuels using image processing and atomization performance analysis of the two fuel sprays injected through a common-rail injection system under various ambient pressure conditions in a high pressure chamber. In order to observe the biodiesel and DME fuel spray behaviors under various ambient pressures, the spray images were analyzed at various times after the start of energization using a visualization system consisting of a high speed camera and two metal halide light sources. In addition, a high pressure chamber that can withstand a pressure of 4 MPa was used for adjusting the ambient pressure. From the spray images, spray characteristics such as the spray tip penetration, cone angle, area, and contour plot at various light intensity levels were analyzed using image conversion processing. Also, the local Sauter mean diameters (SMD) were measured at various axial/radial distances from the nozzle tip by a droplet measuring system to compare the atomization performances of the biodiesel and DME sprays. The results showed that the ambient pressure had a significant effect on the spray characteristics of the fuels at the various experimental conditions. The spray tip penetration and spray area decreased as the ambient pressure increased. The contour plot of the biodiesel and DME sprays showed a high light intensity level in the center regions of the sprays. In addition, it was revealed that the atomization performance of the biodiesel spray was inferior to that of the DME spray at the same injection and ambient conditions. (author)

High temperature tribological properties of plasma-sprayed metallic coatings containing ceramic particles

International Nuclear Information System (INIS)

Dallaire, S.; Legoux, J.G.

1995-01-01

For sealing a moving metal component with a dense silica-based ceramic pre-heated at 800 C, coatings with a low coefficient of friction and moderate wear loss are required. As reported previously, plasma-sprayed coatings containing solid lubricants could reduce sliding wear in high-temperature applications. Plasma-sprayed metal-based coatings containing ceramic particles have been considered for high temperature sealing. Selected metal powders (NiCoCrAlY, CuNi, CuNiIn, Ag, Cu) and ceramic particles (boron nitride, Zeta-B ceramic) were agglomerated to form suitable spray powders. Plasma-sprayed composite coatings and reference materials were tested in a modified pin-on-disc apparatus in which the stationary disc consisted of a dense silica-based ceramic piece initially heated at 800 C and allowed to cool down during tests. The influence of single exposure and repeated contacts with a dense silica-based ceramic material pre-heated to 800 C on the coefficient of friction, wear loss and damage to the ceramic piece was evaluated. Being submitted to a single exposure at high temperature, coatings containing malleable metals such as indium, silver and copper performed well. The outstanding tribological characteristics of the copper-Zeta-B ceramic coating was attributed to the formation of a glazed layer on the surface of this coating which lasted over exposures to high temperature. This glazed layer, composed of fine oxidation products, provided a smooth and polished surface and helped maintaining the coefficient of friction low

Plasma-spraying synthesis of high-performance photocatalytic TiO2 coatings

International Nuclear Information System (INIS)

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

2014-01-01

Anatase (A-) TiO 2 is a photocatalytic material that can decompose air-pollutants, acetaldehyde, bacteria, and so on. In this study, three kinds of powder (A-TiO 2 without HAp, TiO 2 + 10mass%HAp, and TiO 2 +30mass%HAp, where HAp is hydroxyapatite and PBS is polybutylene succinate) were plasma sprayed on biodegradable PBS substrates. HAp powder was mixed with A-TiO 2 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-TiO 2 coatings without HAp. HAp addition improved photocatalytic sterilization when plasma preheating of the PBS was performed

Automatic targeting of plasma spray gun

Science.gov (United States)

Abbatiello, Leonard A.; Neal, Richard E.

1978-01-01

A means for monitoring the material portion in the flame of a plasma spray gun during spraying operations is provided. A collimated detector, sensitive to certain wavelengths of light emission, is used to locate the centroid of the material with each pass of the gun. The response from the detector is then relayed to the gun controller to be used to automatically realign the gun.

Automatic targeting of plasma spray gun

International Nuclear Information System (INIS)

Abbatiello, L.A.; Neal, R.E.

1978-01-01

A means for monitoring the material portion in the flame of a plasma spray gun during spraying operations is described. A collimated detector, sensitive to certain wavelengths of light emission, is used to locate the centroid of the material with each pass of the gun. The response from the detector is then relayed to the gun controller to be used to automatically realign the gun

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

Science.gov (United States)

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

1999-02-01

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

Characterizing Suspension Plasma Spray Coating Formation Dynamics through Curvature Measurements

Science.gov (United States)

Chidambaram Seshadri, Ramachandran; Dwivedi, Gopal; Viswanathan, Vaishak; Sampath, Sanjay

2016-12-01

Suspension plasma spraying (SPS) enables the production of variety of microstructures with unique mechanical and thermal properties. In SPS, a liquid carrier (ethanol/water) is used to transport the sub-micrometric feedstock into the plasma jet. Considering complex deposition dynamics of SPS technique, there is a need to better understand the relationships among spray conditions, ensuing particle behavior, deposition stress evolution and resultant properties. In this study, submicron yttria-stabilized zirconia particles suspended in ethanol were sprayed using a cascaded arc plasma torch. The stresses generated during the deposition of the layers (termed evolving stress) were monitored via the change in curvature of the substrate measured using an in situ measurement apparatus. Depending on the deposition conditions, coating microstructures ranged from feathery porous to dense/cracked deposits. The evolving stresses and modulus were correlated with the observed microstructures and visualized via process maps. Post-deposition bi-layer curvature measurement via low temperature thermal cycling was carried out to quantify the thermo-elastic response of different coatings. Lastly, preliminary data on furnace cycle durability of different coating microstructures were evaluated. This integrated study involving in situ diagnostics and ex situ characterization along with process maps provides a framework to describe coating formation mechanisms, process parametrics and microstructure description.

Experiments on the spray nozzles used in the pressurizer of power reactor

International Nuclear Information System (INIS)

Diao Wentang

1989-04-01

The spray nozzle, which is used in the pressurizer of pressurized water reactor system, usually uses a less differential pressure between the reactor inlet and outlet as the spray drive pressure, but its flow rate is relatively larger. It is difficult to obtain a optimum spray performance of such a nozzle. The experimental results of five types of twenty seven spray nozzles in different structures and sizes with the range of the spray drive pressure from 0.127 to 0.245 MPa and the flow rates from 5 to 50 t/h are given. The main factors affecting spray performances and their distribution characteristics have been found. And some relatively suitable spray structures have been recommended, which can be used as references for improving the spray nozzles used in the pressurizers of existing PWRs or of the PWRs to be built

Temperature measurement in low pressure plasmas. Temperaturmessungen im Niederdruckplasma

Energy Technology Data Exchange (ETDEWEB)

Rosenbauer, K.A.; Wilting, H.; Schramm, G. (Duesseldorf Univ. (Germany, F.R.). Abt. fuer Histologie und Embryologie)

1989-11-01

The present work discusses the influence of various parameters on the substrate temperature in a low pressure plasma. The measurement method chosen utilized Signotherm (Merck) temperature sensors embedded in silicon between two glass substrates. All measurements were made in a 200 G Plasma Processor from Technics Plasma GmbH. The substrate temperature is dependent on the process time, the RF power, the process gas and the position in the chamber. The substrate temperature increases with increasing process time and increasing power. Due to the location of the microwave port from the magnetron to the chamber, the substrate temperature is highest in the center of the chamber. Measurements performed in an air plasma yielded higher results than in an oxygen plasma. (orig.).

Atomic and molecular hydrogen gas temperatures in a low-pressure helicon plasma

Science.gov (United States)

Samuell, Cameron M.; Corr, Cormac S.

2015-08-01

Neutral gas temperatures in hydrogen plasmas are important for experimental and modelling efforts in fusion technology, plasma processing, and surface modification applications. To provide values relevant to these application areas, neutral gas temperatures were measured in a low pressure (radiofrequency helicon discharge using spectroscopic techniques. The atomic and molecular species were not found to be in thermal equilibrium with the atomic temperature being mostly larger then the molecular temperature. In low power operation (measurements near a graphite target demonstrated localised cooling near the sample surface. The temporal evolution of the molecular gas temperature during a high power 1.1 ms plasma pulse was also investigated and found to vary considerably as a function of pressure.

Plasma sprayed alumina-titania coatings

International Nuclear Information System (INIS)

Steeper, T.J.; Rotolico, A.J.; Nerz, J.E.; Riggs, W.L. II; Varacalle, D.J. Jr.; Wilson, G.C.

1992-01-01

This paper presents an experimental study of the air plasma spraying (APS) of alumina-titania powder using argon-hydrogen working gases. This powder system is being used in the fabrication of heater tubes that emulate nuclear fuel tubes for use in thermal-hydraulic testing. Experiments were conducted using a Taguchi fractional-factorial design parametric study. Operating parameters were varied around the typical spray parameters in a systematic design of experiments in order to display the range of plasma processing conditions and their effect on the resultant coatings. The coatings were characterized by hardness and electrical tests, surface profilometry, image analysis, optical metallography, and x-ray diffraction. Coating qualities are discussed with respect to dielectric strength, hardness, porosity, surface roughness, deposition efficiency, and microstructure. attempts are made to correlate the features of the coatings with the changes in operating parameters

Plasma Sprayed Hydroxyapatite Coatings: Influence of Spraying Power on Microstructure

International Nuclear Information System (INIS)

Mohd, S. M.; Abd, M. Z.; Abd, A. N.

2010-01-01

The plasma sprayed hydroxyapatite (HA) coatings are used on metallic implants to enhance the bonding between the implant and bone in human body. The coating process was implemented at different spraying power for each spraying condition. The coatings formed from a rapid solidification of molten and partly molten particles that impact on the surface of substrate at high velocity and high temperature. The study was concentrated on different spraying power that is between 23 to 31 kW. The effect of different power on the coatings microstructure was investigated using scanning electron microscope (SEM) and phase composition was evaluated using X-ray diffraction (XRD) analysis. The coatings surface morphology showed distribution of molten, partially melted particles and some micro-cracks. The produced coatings were found to be porous as observed from the cross-sectional morphology. The coatings XRD results indicated the presence of crystalline phase of HA and each of the patterns was similar to the initial powder. Regardless of different spraying power, all the coatings were having similar XRD patterns.

Production of press moulds by plasma spray forming process

International Nuclear Information System (INIS)

Borisov, Y.; Myakota, I.; Polyakov, S.

2001-01-01

Plasma spray forming process for production of press moulds which are used for manufacture of articles from plastics was developed. The press moulds were produced by plasma spraying of Cu-Al-Fe-alloy powder on surface of a master model. The master models were made from non-metallic materials with heat resistance below 70 C (wood, gypsum etc). Double cooling system which provides for a control of surface model temperature and quenching conditions of sprayed material was designed. It made possible on the one hand to support model surface temperature below 70 C and on the other hand to provide for temperature conditions of martensite transformation in Cu-Al-system with a fixation of metastable ductile α + β 1 -phase. This allowed to decrease residual stresses in sprayed layer (up to 0,5-2,5 MPa), to increase microhardness of the coating material (up to 1200-1800 MPa) and its ductility (σ B = 70-105 MPa, δ = 6-12 %). This plasma spray forming process makes possible to spray thick layers (5-20 mm and more) without their cracking and deformation. The process is used for a production of press moulds which are applied in shoes industry, for fabrication of toys, souvenirs etc. (author)

Nanoparticle formation in a low pressure argon/aniline RF plasma

Science.gov (United States)

Pattyn, C.; Kovacevic, E.; Hussain, S.; Dias, A.; Lecas, T.; Berndt, J.

2018-01-01

The formation of nanoparticles in low temperature plasmas is of high importance for different fields: from astrophysics to microelectronics. The plasma based synthesis of nanoparticles is a complex multi-scale process that involves a great variety of different species and comprises timescales ranging from milliseconds to several minutes. This contribution focuses on the synthesis of nanoparticles in a low temperature, low pressure capacitively coupled plasma containing mixtures of argon and aniline. Aniline is commonly used for the production of polyaniline, a material that belongs to the family of conductive polymers, which has attracted increasing interest in the last few years due to the large number of potential applications. The nanoparticles which are formed in the plasma volume and levitate there due to the collection of negative charges are investigated in this contribution by means of in-situ FTIR spectroscopy. In addition, the plasma is analyzed by means of plasma (ion) mass spectroscopy. The experiments reveal the possibility to synthesize nanoparticles both in continuous wave and in pulsed discharges. The formation of particles in the plasma volume can be suppressed by pulsing the plasma in a specific frequency range. The in-situ FTIR analysis also reveals the influence of the argon plasma on the characteristics of the nanoparticles.

Enhancement of low pressure cold sprayed copper coating adhesion by laser texturing on aluminum substrates

Science.gov (United States)

Knapp, Wolfgang; Gillet, Vincent; Courant, Bruno; Aubignat, Emilie; Costil, Sophie; Langlade, Cécile

2017-02-01

Surface pre-treatment is fundamental in thermal spraying processes to obtain a sufficient bonding strength between substrate and coating. Different pre-treatments can be used, mostly grit-blasting for current industrial applications. This study is focused on Cu-Al2O3 coatings obtained by Low Pressure Cold Spray on AW5083 aluminum alloy substrate. Bonding strength is measured by tensile adhesion test, while deposition efficiency is measured. Substrates are textured by laser, using a pattern of equally spaced grooves with almost constant diameter and variations of depth. Results show that bonding strength is improved up to +81% compared to non-treated substrate, while deposition efficiency remains constant. The study of the samples after rupture reveals a modification of the failure mode, from mixed failure to cohesive failure. A modification of crack propagation is also noticed, the shape of laser textured grooves induces a deviation of cracks inside the coating instead of following the interface between the layers.

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...

A Plasma Focus operated at a very low pressure range

International Nuclear Information System (INIS)

Bruzzone, H.; Grondona, D.; Kelly, H.; Marquez, A.

1990-01-01

Several characteristics of the neutron production and the hard X-ray emission from a Plasma Focus device operating at 30 kV (6 kV of stored energy) and at an unusually low pressure range are presented. (Author)

Reduction of spray pressure leads to less emission and better deposition of spray liquid at high-volume spraying in greenhouse tomato

NARCIS (Netherlands)

Os, van E.A.; Michielsen, J.M.G.P.; Corver, F.J.M.; Berg, van den J.V.; Bruins, M.A.; Porskamp, H.A.J.; Zande, van de J.C.

2005-01-01

In an experimental greenhouse, growing a tomato crop, it was investigated if a reduction in spray pressure could improve the spray result, while, simultaneously, emission to the ground could be reduced. Spray deposition on the leaves and the emission to the ground was evaluated at different spray

Plasma spraying of cerium-doped YAG

Czech Academy of Sciences Publication Activity Database

Ctibor, Pavel; Kubát, J.; Pala, Zdeněk; Nevrlá, Barbara

2014-01-01

Roč. 29, č. 19 (2014), s. 2344-2351 ISSN 0884-2914 R&D Projects: GA ČR(CZ) GAP108/12/1872 Institutional support: RVO:61389021 Keywords : plasma spraying * water-stabilized plasma Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.647, year: 2014 http://dx.doi.org/10.1557/jmr.2014.251

Molybdenum plasma spray powder, process for producing said powder, and coating made therefrom

International Nuclear Information System (INIS)

Lafferty, W.D.; Cheney, R.F.; Pierce, R.H.

1979-01-01

Plasma spray powders of molybdenum particles containing 0.5 to 15 weight percent oxygen and obtained by reacting molybdenum particles with oxygen or oxides in a plasma, form plasma spray coatings exhibiting hardness comparable to flame sprayed coatings formed from molybdenum wire and plasma coatings of molybdenum powders. Such oxygen rich molybdenum powders may be used to form wear resistant coatings, such as for piston rings. (author)

Polydiagnostic calibration performed on a low pressure surface wave sustained argon plasma

NARCIS (Netherlands)

Vries, de N.; Palomares, J.M.; Iordanova, E.I.; Veldhuizen, van E.M.; Mullen, van der J.J.A.M.

2008-01-01

The electron density and electron temperature of a low pressure surface wave sustained argon plasma have been determined using passive and active (laser) spectroscopic methods simultaneously. In this way the validity of the various techniques is established while the plasma properties are determined

Research Into Ni-Cr-Si-B Coating Sprayed Onto Aluminium Substrate Using the Method of Plasma Spray

Directory of Open Access Journals (Sweden)

Raimonda Lukauskaitė

2013-02-01

Full Text Available The article deals with Ni base coatings deposited on aluminium substrate applying the method of plasma spray. The purpose of the conducted research is to improve the physical and mechanical properties of coatings on the surface of aluminium alloy work pieces. Spraying on aluminium alloys encounters serious problems, and therefore this work analyses the ways to make the situation more favourable. Before spraying, the surfaces of substrates were modified employing chemical and mechanical pre-treatment methods. The aim of pre-treating aluminium alloys was to remove oxide layers from the aluminium surface. Coating microstructures and porosity were characterised applying optical microscopy. Differences in the roughness of pre-treated surfaces have been determined referring to profilometry. The paper investigates the influence of the adhesion of plasma spray coatings on aluminium surface pretreatment. Microhardness technique was applied for measuring the hardness of coatings. The study also describes and compares the mechanical properties of Ni base coatings deposited on different pre-treated aluminium substrates using plasma spray.Article in Lithuanian

Research Into Ni-Cr-Si-B Coating Sprayed Onto Aluminium Substrate Using the Method of Plasma Spray

Directory of Open Access Journals (Sweden)

Raimonda Lukauskaitė

2012-12-01

Full Text Available The article deals with Ni base coatings deposited on aluminium substrate applying the method of plasma spray. The purpose of the conducted research is to improve the physical and mechanical properties of coatings on the surface of aluminium alloy work pieces. Spraying on aluminium alloys encounters serious problems, and therefore this work analyses the ways to make the situation more favourable. Before spraying, the surfaces of substrates were modified employing chemical and mechanical pre-treatment methods. The aim of pre-treating aluminium alloys was to remove oxide layers from the aluminium surface. Coating microstructures and porosity were characterised applying optical microscopy. Differences in the roughness of pre-treated surfaces have been determined referring to profilometry. The paper investigates the influence of the adhesion of plasma spray coatings on aluminium surface pretreatment. Microhardness technique was applied for measuring the hardness of coatings. The study also describes and compares the mechanical properties of Ni base coatings deposited on different pre-treated aluminium substrates using plasma spray.Article in Lithuanian

Exploration of Impinging Water Spray Heat Transfer at System Pressures Near the Triple Point

Science.gov (United States)

Golliher, Eric L.; Yao, Shi-Chune

2013-01-01

The heat transfer of a water spray impinging upon a surface in a very low pressure environment is of interest to cooling of space vehicles during launch and re-entry, and to industrial processes where flash evaporation occurs. At very low pressure, the process occurs near the triple point of water, and there exists a transient multiphase transport problem of ice, water and water vapor. At the impingement location, there are three heat transfer mechanisms: evaporation, freezing and sublimation. A preliminary heat transfer model was developed to explore the interaction of these mechanisms at the surface and within the spray.

Plasma-sprayed tantalum/alumina cermets

International Nuclear Information System (INIS)

Kramer, C.M.

1977-12-01

Cermets of tantalum and alumina were fabricated by plasma spraying, with the amount of alumina varied from 0 to 65 percent (by volume). Each of four compositions was then measured for tensile strength, elastic modulus, and coefficient of thermal expansion. In general, strength and strain to failure decreased with increasing alumina content: 62 MPa for 100 percent Ta to 19 MPa for 35 v percent Ta. A maximum of 0.1 percent strain was observed for the sprayed 100 percent Ta specimens. The coefficient of thermal expansion measured for the pure Ta was 6.2 (10 -6 )/K

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.

Process maps for plasma spray: Part 1: Plasma-particle interactions

International Nuclear Information System (INIS)

Gilmore, Delwyn L.; Neiser, Richard A. Jr.; Wan, Yuepeng; Sampath, Sanjay

2000-01-01

This is the first paper of a two part series based on an integrated study carried out at Sandia National Laboratories and the State University of New York at Stony Brook. The aim of the study is to develop a more fundamental understanding of plasma-particle interactions, droplet-substrate interactions, deposit formation dynamics and microstructural development as well as final deposit properties. The purpose is to create models that can be used to link processing to performance. Process maps have been developed for air plasma spray of molybdenum. Experimental work was done to investigate the importance of such spray parameters as gun current, auxiliary gas flow, and powder carrier gas flow. In-flight particle diameters, temperatures, and velocities were measured in various areas of the spray plume. Samples were produced for analysis of microstructures and properties. An empirical model was developed, relating the input parameters to the in-flight particle characteristics. Multi-dimensional numerical simulations of the plasma gas flow field and in-flight particles under different operating conditions were also performed. In addition to the parameters which were experimentally investigated, the effect of particle injection velocity was also considered. The simulation results were found to be in good general agreement with the experimental data

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

International Nuclear Information System (INIS)

Jiang Xianliang

2002-01-01

nano-crystalline powders of ω(Al 2 O 3 ) = 95%, ω(TiO 2 ) = 3%, and ω(SiO 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) μm. 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 lower microhardness than conventional microstructured coatings, the toughness of the nano-structured ceramic coatings is significantly improved

The Influence of Spray Parameters on the Characteristics of Hydroxyapatite In-Flight Particles, Splats and Coatings by Micro-plasma Spraying

Science.gov (United States)

Liu, Xiao-mei; He, Ding-yong; Wang, Yi-ming; Zhou, Zheng; Wang, Guo-hong; Tan, Zhen; Wang, Zeng-jie

2018-04-01

Hydroxyapatite (HA) is one of the most important bioceramic materials used in medical implants. The structure of HA coatings is closely related to their manufacturing process. In the present study, HA coatings were deposited on Ti-6Al-4V substrate by micro-plasma spraying. Results show that three distinct HA coatings could be obtained by changing the spraying power from 0.5 to 1.0 kW and spraying stand-off distance from 60 to 110 mm: (1) high crystallinity (93.3%) coatings with porous structure, (2) high crystallinity coatings (86%) with columnar structure, (3) higher amorphous calcium phosphate (ACP, 50%) coatings with dense structure. The in-flight particles melting state and splat topography was analyzed to better understand the formation mechanism of three distinct HA coatings. Results show that HA coatings sprayed at low spraying power and short stand-off distance exhibit high crystallinity and porosity is attributed to the presence of partially melted particles. High crystallinity HA coatings with (002) crystallographic texture could be deposited due to the complete melting of the in-flight particles and low cooling rate of the disk shape splats under higher spraying power and shorter SOD. However, splashed shape splats with relative high cooling can be provided by increasing SOD, which leads to the formation of ACP.

Consolidation of tungsten disilicide by plasma spraying

Czech Academy of Sciences Publication Activity Database

Brožek, Vlastimil; Ctibor, Pavel; Matějíček, Jiří; Rohan, Pavel; Janča, J.

2007-01-01

Roč. 52, č. 3 (2007), s. 311-320 ISSN 0001-7043 R&D Projects: GA ČR(CZ) GA104/05/0540 Institutional research plan: CEZ:AV0Z20430508 Keywords : Water stabilized plasma * tungsten disilicide * plasma deposition * thermal spray coatings Subject RIV: JJ - Other Materials

Preparation and Characterization of Plasma-Sprayed Ultrafine Chromium Oxide Coatings

International Nuclear Information System (INIS)

Lin Feng; Jiang Xianliang; Yu Yueguang; Zeng Keli; Ren Xianjing; Li Zhenduo

2007-01-01

Ultrafine chromium oxide coatings were prepared by plasma spraying with ultrafine feedstock. Processing parameters of plasma spraying were optimized. Optical microscope (OM) was used to observe the microstructure of the ultrafine chromium oxide coatings. Scanning electron microscopy (SEM) was used to observe the morphology and particle size of ultrafine powder feedstock as well as to examine the microstructure of the chromium oxide coating. In addition, hardness and bonding strength of the ultrafine chromium oxide coatings were measured. The results showed that the optimized plasma spraying parameters were suitable for ultrafine chromium oxide coating and the properties and microstructure of the optimized ultrafine chromium oxide coating were superior compared to conventional chromium oxide wear resistant coatings

Thermal plasma spheroidization and spray deposition of barium titanate powder and characterization of the plasma sprayable powder

Energy Technology Data Exchange (ETDEWEB)

Pakseresht, A.H., E-mail: amirh_pak@yahoo.com [Department of Ceramics, Materials and Energy Research Center, P.O. Box 31787-316, Karaj (Iran, Islamic Republic of); Rahimipour, M.R. [Department of Ceramics, Materials and Energy Research Center, P.O. Box 31787-316, Karaj (Iran, Islamic Republic of); Vaezi, M.R. [Department of Nanotechnology and Advanced Materials, Materials and Energy Research Center, P.O. Box 31787-316, Karaj (Iran, Islamic Republic of); Salehi, M. [Department of Materials Engineering, Isfahan University of Technology, P.O. Box 84156-83111, Isfahan (Iran, Islamic Republic of)

2016-04-15

In this paper, atmospheric plasma spray method was used to produce dense plasma sprayable powder and thick barium titanate film. In this regard, the commercially feedstock powders were granulated and spheroidized by the organic binder and the thermal spray process, respectively. Scanning electron microscopy was used to investigate the microstructure of the produced powders and the final deposits. X-ray diffraction was also implemented to characterize phase of the sprayed powder. The results indicated that spheroidized powder had suitable flowability as well as high density. The micro-hardness of the film produced by the sprayed powders was higher than that of the film deposited by the irregular granules. Additionally, relative permittivity of the films was increased by decreasing the defects from 160 to 293 for film deposited using spheroidized powder. The reduction in the relative permittivity of deposits, in comparison with the bulk material, was due to the existence of common defects in the thermal spray process. - Highlights: • We prepare sprayable BaTiO{sub 3} powder with no or less inside voids for plasma spray application for first time. • The sprayable powder has good flow characteristics and high density. • Powder spheroidization via plasma spray improves the hardness and dielectric properties of the deposited film.

Thermal plasma spheroidization and spray deposition of barium titanate powder and characterization of the plasma sprayable powder

International Nuclear Information System (INIS)

Pakseresht, A.H.; Rahimipour, M.R.; Vaezi, M.R.; Salehi, M.

2016-01-01

In this paper, atmospheric plasma spray method was used to produce dense plasma sprayable powder and thick barium titanate film. In this regard, the commercially feedstock powders were granulated and spheroidized by the organic binder and the thermal spray process, respectively. Scanning electron microscopy was used to investigate the microstructure of the produced powders and the final deposits. X-ray diffraction was also implemented to characterize phase of the sprayed powder. The results indicated that spheroidized powder had suitable flowability as well as high density. The micro-hardness of the film produced by the sprayed powders was higher than that of the film deposited by the irregular granules. Additionally, relative permittivity of the films was increased by decreasing the defects from 160 to 293 for film deposited using spheroidized powder. The reduction in the relative permittivity of deposits, in comparison with the bulk material, was due to the existence of common defects in the thermal spray process. - Highlights: • We prepare sprayable BaTiO_3 powder with no or less inside voids for plasma spray application for first time. • The sprayable powder has good flow characteristics and high density. • Powder spheroidization via plasma spray improves the hardness and dielectric properties of the deposited film.

Quantitative X-ray measurements of high-pressure fuel sprays from a production heavy duty diesel injector

Energy Technology Data Exchange (ETDEWEB)

Ramirez, A.I.; Som, S.; Aggarwal, Suresh K. [University of Illinois at Chicago, Department of Mechanical and Industrial Engineering, Chicago, IL (United States); Kastengren, A.L.; El-Hannouny, E.M.; Longman, D.E.; Powell, C.F. [Argonne National Laboratory, Energy Systems Division, Argonne, IL (United States)

2009-07-15

A quantitative and time-resolved X-ray radiography technique has been used for detailed measurements of high-pressure fuel sprays in the near-nozzle region of a diesel engine injector. The technique provides high spatial and temporal resolution, especially in the relatively dense core region. A single spray plume from a hydraulically actuated electronically controlled unit injector model 315B injector with a 6-hole nozzle was isolated and studied at engine-like densities for two different injection pressures. Optical spray imaging was also employed to evaluate the effectiveness of the shield used to isolate a single spray plume. The steady state fuel distributions for both injection pressures are similar and show a dense spray region along the axis of the spray, with the on-axis spray density decreasing as the spray progresses downstream. The higher injection pressure case exhibits a larger cone angle and spray broadening at the exit of the nozzle. For some time periods, the near-nozzle penetration speed is lower for the high injection pressure case than the low injection pressure case, which is unexpected, but can be attributed to the needle and flow dynamics inside the injector causing slower pressure build-up for the former case. Rate of injection testing was performed to further understand near-nozzle behavior. Mass distribution data were obtained and used to find mass-averaged velocity of the spray. Comparisons of the radiography data with that from a common rail single-hole light duty injectors under similar injection conditions show several significant differences. The current data show a larger cone angle and lower penetration speed than that from the light-duty injector. Moreover, these data display a Gaussian mass distribution across the spray near the injector, whereas in previous light-duty injector measurements, the mass distribution had steeper sides and a flatter peak. Measurements are also used to examine the spray models in the STAR-CD software

Quantitative X-ray measurements of high-pressure fuel sprays from a production heavy duty diesel injector

Science.gov (United States)

Ramírez, A. I.; Som, S.; Aggarwal, Suresh K.; Kastengren, A. L.; El-Hannouny, E. M.; Longman, D. E.; Powell, C. F.

2009-07-01

A quantitative and time-resolved X-ray radiography technique has been used for detailed measurements of high-pressure fuel sprays in the near-nozzle region of a diesel engine injector. The technique provides high spatial and temporal resolution, especially in the relatively dense core region. A single spray plume from a hydraulically actuated electronically controlled unit injector model 315B injector with a 6-hole nozzle was isolated and studied at engine-like densities for two different injection pressures. Optical spray imaging was also employed to evaluate the effectiveness of the shield used to isolate a single spray plume. The steady state fuel distributions for both injection pressures are similar and show a dense spray region along the axis of the spray, with the on-axis spray density decreasing as the spray progresses downstream. The higher injection pressure case exhibits a larger cone angle and spray broadening at the exit of the nozzle. For some time periods, the near-nozzle penetration speed is lower for the high injection pressure case than the low injection pressure case, which is unexpected, but can be attributed to the needle and flow dynamics inside the injector causing slower pressure build-up for the former case. Rate of injection testing was performed to further understand near-nozzle behavior. Mass distribution data were obtained and used to find mass-averaged velocity of the spray. Comparisons of the radiography data with that from a common rail single-hole light duty injectors under similar injection conditions show several significant differences. The current data show a larger cone angle and lower penetration speed than that from the light-duty injector. Moreover, these data display a Gaussian mass distribution across the spray near the injector, whereas in previous light-duty injector measurements, the mass distribution had steeper sides and a flatter peak. Measurements are also used to examine the spray models in the STAR-CD software.

Characterization of the full cone pressure swirl spray nozzles for the nuclear reactor containment spray system

Energy Technology Data Exchange (ETDEWEB)

Jain, Manish [Department of Mechanical Engineering, I.I.T., Bombay, Powai, Mumbai (India); John, Benny [Nuclear Power Corporation of India Limited, Mumbai (India); Iyer, K.N. [Department of Mechanical Engineering, I.I.T., Bombay, Powai, Mumbai (India); Prabhu, S.V., E-mail: svprabhu@iitb.ac.in [Department of Mechanical Engineering, I.I.T., Bombay, Powai, Mumbai (India)

2014-07-01

Highlights: • Full cone spray pressure swirl nozzle with X-Vane is studied. • Laser illuminated imaging technique is used. • Correlations for coefficient of discharge, spray cone angle and SMD are suggested. • Droplet size and mass fraction distribution is measured. • Inviscid theory predicts the coefficient of discharge. - Abstract: The objective of the present study is to characterize a full cone pressure swirl nozzle for the Containment Spray System (CSS) of Indian Pressurized heavy Water reactors (IPHWR). The influence of Reynolds number and geometric parameters on the coefficient of discharge, spray cone angle, mass flux density distribution, droplet size distribution, Sauter mean diameter (SMD is studied for full cone pressure swirl full cone nozzles. The nozzles of orifice diameter range from 1.3 to 7.2 mm are studied. Experiments are conducted with water at room temperature as the working medium. The nozzles are operated with the pressure ranging from 1 to 8 bar. The measurements of the drop size distributions are performed with laser illuminated imaging technique. The spray cone-angle of the full cone nozzles is measured by the evaluation of images recorded with a camera using IMAGE J software. Correlations for coefficient of discharge, spray cone angle and Sauter mean diameter are suggested on the basis of the experimental results. Rosin–Rammler model and Nukiyama–Tanasawa distributions predict the mass fraction distribution reasonably well. However, the droplet size distribution is predicted by Nukiyama-Tanasawa model only.

Advanced Diagnostics for High Pressure Spray Combustion.

Energy Technology Data Exchange (ETDEWEB)

Skeen, Scott A.; Manin, Julien Luc; Pickett, Lyle M.

2014-06-01

The development of accurate predictive engine simulations requires experimental data to both inform and validate the models, but very limited information is presently available about the chemical structure of high pressure spray flames under engine- relevant conditions. Probing such flames for chemical information using non- intrusive optical methods or intrusive sampling techniques, however, is challenging because of the physical and optical harshness of the environment. This work details two new diagnostics that have been developed and deployed to obtain quantitative species concentrations and soot volume fractions from a high-pressure combusting spray. A high-speed, high-pressure sampling system was developed to extract gaseous species (including soot precursor species) from within the flame for offline analysis by time-of-flight mass spectrometry. A high-speed multi-wavelength optical extinction diagnostic was also developed to quantify transient and quasi-steady soot processes. High-pressure sampling and offline characterization of gas-phase species formed following the pre-burn event was accomplished as well as characterization of gas-phase species present in the lift-off region of a high-pressure n-dodecane spray flame. For the initial samples discussed in this work several species were identified, including polycyclic aromatic hydrocarbons (PAH); however, quantitative mole fractions were not determined. Nevertheless, the diagnostic developed here does have this capability. Quantitative, time-resolved measurements of soot extinction were also accomplished and the novel use of multiple incident wavelengths proved valuable toward characterizing changes in soot optical properties within different regions of the spray flame.

Degradation of nitride coatings in low-pressure gas discharge plasma

Science.gov (United States)

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

2017-12-01

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

Laser induced plasma methodology for ignition control in direct injection sprays

International Nuclear Information System (INIS)

Pastor, José V.; García-Oliver, José M.; García, Antonio; Pinotti, Mattia

2016-01-01

Highlights: • Laser Induced Plasma Ignition system is designed and applied to a Diesel Spray. • A method for quantification of the system effectiveness and reliability is proposed. • The ignition system is optimized in atmospheric and engine-like conditions. • Higher system effectiveness is reached with higher ambient density. • The system is able to stabilize Diesel combustion compared to auto-ignition cases. - Abstract: New combustion modes for internal combustion engines represent one of the main fields of investigation for emissions control in transportation Industry. However, the implementation of lean fuel mixture condition and low temperature combustion in real engines is limited by different unsolved practical issues. To achieve an appropriate combustion phasing and cycle-to-cycle control of the process, the laser plasma ignition system arises as a valid alternative to the traditional electrical spark ignition system. This paper proposes a methodology to set-up and optimize a laser induced plasma ignition system that allows ensuring reliability through the quantification of the system effectiveness in the plasma generation and positional stability, in order to reach optimal ignition performance. For this purpose, experimental tests have been carried out in an optical test rig. At first the system has been optimized in an atmospheric environment, based on the statistical analysis of the plasma records taken with a high speed camera to evaluate the induction effectiveness and consequently regulate and control the system settings. The same optimization method has then been applied under engine-like conditions, analyzing the effect of thermodynamic ambient conditions on the plasma induction success and repeatability, which have shown to depend mainly on ambient density. Once optimized for selected engine conditions, the laser plasma induction system has been used to ignite a direct injection Diesel spray, and to compare the evolution of combustion

Ceramic plasma-sprayed coating of melting crucibles for casting metal fuel slugs

International Nuclear Information System (INIS)

Kim, Ki Hwan; Lee, Chong Tak; Lee, Chan Bock; Fielding, R.S.; Kennedy, J.R.

2013-01-01

Thermal cycling and melt reaction studies of ceramic coatings plasma-sprayed on Nb substrates were carried out to evaluate the performance of barrier coatings for metallic fuel casting applications. Thermal cycling tests of the ceramic plasma-sprayed coatings to 1450 °C showed that HfN, TiC, ZrC, and Y 2 O 3 coating had good cycling characteristics with few interconnected cracks even after 20 cycles. Interaction studies by 1550 °C melt dipping tests of the plasma-sprayed coatings also indicated that HfN and Y 2 O 3 do not form significant reaction layer between U–20 wt.% Zr melt and the coating layer. Plasma-sprayed Y 2 O 3 coating exhibited the most promising characteristics among HfN, TiC, ZrC, and Y 2 O 3 coating

Effect of Gas Pressure on Polarization of SOFC Cathode Prepared by Plasma Spray

Science.gov (United States)

Li, Cheng-Xin; Wang, Zhun-Zhun; Liu, Shuai; Li, Chang-Jiu

2013-06-01

A cermet-supported tubular SOFC was fabricated using thermal spray. The cell performance was investigated at temperatures from 750 to 900 °C and pressures from 0.1 to 0.5 MPa to examine the effect of operating gas pressure on the cell performance. The influence of gas pressure on the cathodic polarization was studied through the electrochemical impedance approach to examine the controlling electrochemical processes during cell operation. Results show that increasing the operating gas pressure improves the power output performance significantly. When the gas pressure is increased from 0.1 to 0.3 MPa, the maximum power density is increased by a factor of 32% at a temperature of 800 °C. The cathode polarization decreases significantly with the increase of the gas pressure. The electrochemical analysis shows that the main control processes of the cathode reaction are the oxygen species transfer at the three-phase boundary and oxygen diffusion on the surface or in the bulk of the cathode, which are enhanced with increasing gas pressure.

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

International Nuclear Information System (INIS)

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

2001-01-01

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

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

Directory of Open Access Journals (Sweden)

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

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.

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.

New generation of plasma-sprayed mullite coatings on silicon carbide

Science.gov (United States)

Lee, Kang N.; Miller, Robert A.; Jacobson, Nathan S.

1995-01-01

Mullite is promising as a protective coating for silicon-based ceramics in aggressive high-temperature environments. Conventionally plasma-sprayed mullite on SiC tends to crack and debond on thermal cycling. It is shown that this behavior is due to the presence of amorphous mullite in the conventionally sprayed mullite. Heating the SiC substrate during the plasma spraying eliminated the amorphous phase and produced coatings with dramatically improved properties. The new coating exhibits excellent adherence and crack resistance under thermal cycling between room temperature and 1000 to 1400 C. Preliminary tests showed good resistance to Na2CO3-induced hot corrosion.

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.

The Influence of Shaping Air Pressure of Pneumatic Spray Gun

Science.gov (United States)

Chen, Wenzhuo; Chen, Yan; Pan, Haiwei; Zhang, Weiming; Li, Bo

2018-02-01

The shaping air pressure is a very important parameter in the application of pneumatic spray gun, and studying its influence on spray flow field and film thickness distribution has practical values. In this paper, Euler-Lagrangian method is adopted to describe the two-phase spray flow of pneumatic painting process, and the air flow fields, spray patterns and dynamic film thickness distributions were obtained with the help of the computational fluid dynamics code—ANSYS Fluent. Results show that with the increase of the shaping air pressure, the air phase flow field spreads in the plane perpendicular to the shaping air hole plane, the spray pattern becomes narrower and flatter, and the width of the dynamic film increases with the reduced maximum value of the film thickness. But the film thickness distribution seems to change little with the shaping air pressure decreasing from 0.6bar to 0.9bar.

Conditions for sustaining low-pressure plasma columns by travelling electromagnetic UHF waves

International Nuclear Information System (INIS)

Benova, E.; Zhelyazkov, I.

1997-01-01

The paper considers the conditions for sustaining low-pressure plasma columns by travelling electromagnetic waves in symmetric and dipolar modes, respectively. The treatment is fully electrodynamic. It is shown that the wave energy flux along the plasma column determines the conditions for sustaining the discharge. In particular as the plasma is sustained by a symmetric wave whose flux depends mainly on the radial distribution of the wave electric field whilst for a dipolar wave sustained plasma the flux is specified by the magnitude of the axial wave field component at the plasma-dielectric interface. (orig.)

Mechanical Properties of Plasma Sprayed Alumina Coatings

Czech Academy of Sciences Publication Activity Database

Kovářík, O.; Nohava, Jiří; Siegel, J.

2003-01-01

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

Particle melting and particle/plasma interactions in DC and RF plasmas: a modeling study. (Volumes I and II)

International Nuclear Information System (INIS)

Wei, D.Y.C.

1987-01-01

Integral process models were developed to predict particle melting in both DC and RF plasmas. Specifically, a numerical model has been developed to predict the temperature history of particles injected in a low pressure DC plasma jet. The temperature and velocity fields of the plasma jet are predicted as a free jet by solving the parabolized Navier-Stokes equations using a spatial marching scheme. Correction factors were introduced to take into account non continuum effects encountered in the low pressure environment. The plasma jet profiles as well as the particle/plasma interactions under different jet pressure ratios (from underexpanded to overexpanded) were investigated. The flow and temperature fields in the RF plasma torch are calculated using the axisymmetric Navier-Stokes equations based on the primitive variables, along with pseudo two-dimensional electromagnetic field equations. Particle trajectories and heat transfer characteristics in both DC and RF plasmas are calculated using predicted plasma jet profiles. Particle melting efficiencies in both DC and RF plasmas are evaluated and compared using model alloy systems. Based on the theoretical considerations, an alternative route of plasma spraying process (hybrid plasma spraying process) is proposed. An evaluation of particle melting in hybrid plasma jets had indicated that further improvement in deposit properties could be made

Vacuum-plasma-sprayed silicon coatings

International Nuclear Information System (INIS)

Varacalle, D.J. Jr.; Herman, H.; Bancke, G.A.; Burchell, T.D.; Romanoski, G.R.

1991-01-01

Vacuum plasma spraying produces well-bonded dense stress-free coatings for a variety of materials on a wide range of substrates. The process is used in many industries for the excellent wear, corrosion resistance and high temperature behavior of the fabricated coatings. In this study, silicon metal was deposited on graphite to study the feasibility of preventing corrosion and oxidation of graphite components for nuclear reactors. Operating parameters were varied in a Taguchi design of experiments to display the range of the plasma processing conditions and their effect on the measured coating characteristics. The coating attributes evaluated were thickness, porosity, microhardness and phase content. This paper discusses the influence of the processing parameters on as-sprayed coating qualities. The paper also discusses the effect of thermal cycling on silicon samples in an inert helium atmosphere. The diffraction spectrum for a sample that experienced a 1600degC temperature cycle indicated that more than 99% of the coating transformed to β-SiC. The silicon coatings protected the graphite substrates from oxidation in one experiment. (orig.)

Characterization of Fe-based alloy coating deposited by supersonic plasma spraying

International Nuclear Information System (INIS)

Piao, Zhong-yu; Xu, Bin-shi; Wang, Hai-dou; Wen, Dong-hui

2013-01-01

Highlights: • Fe-based coating exhibited few oxides, high density and bond strength. • Amorphous/nanocrystalline phases were found in the coating. • Formation mechanism of excellent coating was investigated. -- Abstract: The objective of the present study is to characterize the Fe-based alloy coating deposited by the supersonic plasma spraying process. The condition of the melting particles was in situ monitored. The microstructure of the coating was examined by scanning electron microscope and high resolution transmission electron microscope. The phase composition was examined by X-ray diffraction. The microhardness and porosity were also measured, respectively. Results show the prepared coatings have excellent properties, such as few oxides, high microhardness and a low porosity amount. At the same time, a mass of amorphous/nanocrystalline phases was found in the coating. The mechanism of the formation of amorphous/nanocrystalline phases was investigated. The appropriate material composition of spraying material and flash set process of plasma spraying are the key factors. Moreover, the mechanism for oxidation resistance is also investigated, where the separation between melting metal and oxygen by the formation of SiO 2 films is the key factor

Advanced Microstructural Study of Suspension Plasma Sprayed Hydroxyapatite Coatings

Science.gov (United States)

Podlesak, Harry; Pawlowski, Lech; D'Haese, Romain; Laureyns, Jacky; Lampke, Thomas; Bellayer, Severine

2010-03-01

Fine, home-synthesized, hydroxyapatite powder was formulated with water and alcohol to obtain a suspension used to plasma spray coatings onto a titanium substrate. The deposition process was optimized using statistical design of 2 n experiments with two variables: spray distance and electric power input to plasma. X-ray diffraction (XRD) was used to determine quantitatively the phase composition of obtained deposits. Raman microscopy and electron probe microanalysis (EPMA) enabled localization of the phases in different positions of the coating cross sections. Transmission electron microscopic (TEM) study associated with energy-dispersive x-ray spectroscopy (EDS) enabled visualization and analysis of a two-zone microstructure. One zone contained crystals of hydroxyapatite, tetracalcium phosphate, and a phase rich in calcium oxide. This zone included lamellas, usually observed in thermally sprayed coatings. The other zone contained fine hydroxyapatite grains that correspond to nanometric and submicrometric solids from the suspension that were agglomerated and sintered in the cold regions of plasma jet and on the substrate.

An evaluation of the electric arc spray and (HPPS) processes for the manufacturing of high power plasma spraying MCrAIY coatings

Science.gov (United States)

Sacriste, D.; Goubot, N.; Dhers, J.; Ducos, M.; Vardelle, A.

2001-06-01

The high power plasma torch (PlazJet) can be used to spray refractory ceramics with high spray rates and deposition efficiency. It can provide dense and hard coating with high bond strengths. When manufacturing thermal barrier coatings, the PlazJet gun is well adapted to spraying the ceramic top coat but not the MCrAIY materials that are used as bond coat. Arc spraying can compete with plasma spraying for metallic coatings since cored wires can be used to spray alloys and composites. In addition, the high production rate of arc spraying enables a significant decrease in coating cost. This paper discusses the performances of the PlazJet gun, and a twin-wire are spray system, and compares the properties and cost of MCrAIY coatings made with these two processes. For arc spraying, the use of air or nitrogen as atomizing gas is also investigated.

Characterization of plasma sprayed NiCrAlY-Yttria stabilized zirconia coatings

International Nuclear Information System (INIS)

Bhave, V.S.; Rakhasia, R.H.; Tripathy, P.K.; Hubli, R.C.; Sengupta, P.; Bhanumurthy; Satpute, R.U.; Sreekumar, K.P.; Thiyagarajan, T.K.; Padmanabhan, P.V.A.

2004-01-01

Plasma sprayed coatings of yttria stabilized zirconia are used in many advanced technologies for thermal and chemical barrier applications. Development and characterization of NiCrAlY-yttria stabilized zirconia duplex coatings on Inconel substrates is reported in this paper. Plasma spraying was carried out using the 40 kW atmospheric plasma spray facility at the Laser and Plasma Technology Division, BARC. A bond coat of NiCrAlY was deposited on Inconel substrates and yttria stabilized zirconia (YSZ) was deposited over the bond coat. The coatings have been characterized by x-ray diffraction and EPMA. It is observed that the coating characteristics are affected by the input power to the torch. (author)

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.

PLASMA SPRAYING OF REFRACTORY CERMETS BY THE WATER-STABILIZED SPRAY (WSP®) SYSTEM

Czech Academy of Sciences Publication Activity Database

Ctibor, Pavel; Brožek, V.; Cheong, D.-I.; Chráska, Pavel

2009-01-01

Roč. 54, č. 3 (2009), s. 241-253 ISSN 0001-7043 Institutional research plan: CEZ:AV0Z20430508 Keywords : Plasma spraying * cermet coatings * microhardness * zirconium carbide * tungsten Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

Plasma-sprayed titanium coating to polyetheretherketone improves the bone-implant interface.

Science.gov (United States)

Walsh, William R; Bertollo, Nicky; Christou, Chrisopher; Schaffner, Dominik; Mobbs, Ralph J

2015-05-01

Rapid and stable fixation at the bone-implant interface would be regarded as one of the primary goals to achieve clinical efficacy, regardless of the surgical site. Although mechanical and physical properties of polyetheretherketone (PEEK) provide advantages for implant devices, the hydrophobic nature and the lack of direct bone contact remains a limitation. To examine the effects of a plasma-sprayed titanium coated PEEK on the mechanical and histologic properties at the bone-implant interface. A preclinical laboratory study. Polyetheretherketone and plasma-sprayed titanium coated PEEK implants (Ti-bond; Spinal Elements, Carlsbad, CA, USA) were placed in a line-to-line manner in cortical bone and in a press-fit manner in cancellous bone of adult sheep using an established ovine model. Shear strength was assessed in the cortical sites at 4 and 12 weeks, whereas histology was performed in cortical and cancellous sites at both time points. The titanium coating dramatically improved the shear strength at the bone-implant interface at 4 weeks and continued to improve with time compared with PEEK. Direct bone ongrowth in cancellous and cortical sites can be achieved using a plasma-sprayed titanium coating on PEEK. Direct bone to implant bonding can be achieved on PEEK in spite of its hydrophobic nature using a plasma-sprayed titanium coating. The plasma-sprayed titanium coating improved mechanical properties in the cortical sites and the histology in cortical and cancellous sites. Copyright © 2015 Elsevier Inc. All rights reserved.

Plasma transferred arc surface modification of atmospheric plasma sprayed ceramic coatings

Energy Technology Data Exchange (ETDEWEB)

Ulutan, Mustafa; Kilicay, Koray; Kaya, Esad; Bayar, Ismail [Dept. of Mechanical Engineering, Eskisehir Osmangazi University, Eskisehir (Turkmenistan)

2016-08-15

In this study, a 90MnCrV8 steel surface was coated with aluminum oxide and chromium oxide powders through the Atmospheric plasma spray (APS) and Plasma transferred arc (PTA) methods. The effects of PTA surface melting on the microstructure, hardness, and wear behavior were investigated. The microstructures of plasma-sprayed and modified layers were characterized by Optical microscopy (OM), Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDS). The dry-sliding wear properties of the samples were determined through the ball-on-disk wear test method. Voids, cracks, and nonhomogeneous regions were observed in the microstructure of the APS ceramic-coated surface. These microstructure defects were eliminated by the PTA welding process. The microhardness of the samples was increased. Significant reductions in wear rate were observed after the PTA surface modification. The wear resistance of ceramic coatings increased 7 to 12 times compared to that of the substrate material.

Energy considerations in spraying process of a spill-return pressure-swirl atomizer

International Nuclear Information System (INIS)

Jedelsky, Jan; Jicha, Miroslav

2014-01-01

Graphical abstract: - Highlights: • We analyse energy conversion in simplex and spill-return pressure-swirl atomizer. • Inlet (pressure) energy converts into liquid motion with nozzle efficiency ∼58%. • Kinetic energy of developed spray at closed spill line is ∼33% of the inlet energy. • It consists of energy of droplets (∼2/3) and entrained air (1/3). • Atomization efficiency is <0.3%; it declines with inlet pressure and spill opening. - Abstract: The work focuses on energy conversion during the internal flow, discharge and formation of the spray from a pressure-swirl (PS) atomizer in the simplex as well as spill-return mode. Individual energy forms are described in general and assessed experimentally for a particular PS atomizer and light heating oil as a medium. The PS spray was observed at various loads to investigate the liquid breakup process and the spray characteristics. Spatially resolved diameters and droplet velocities, measured by means of phase-Doppler anemometry, served for estimation of the energy characteristics in the PS spray. The input energy given by the potential energy of the supplied liquid partially converts into the kinetic energy (KE) in the swirling ports with hydraulic loss in per cent scale. Most of the pressure drop is associated with rotational motion in the swirl chamber with total conversion efficiency at the exit orifice ∼58%. The rest of the input energy ends up as friction loss, leaving room for improvement. The overall value (ID 32 ) of the Sauter mean diameter of droplets in the spray, D 32 , varies with pressure drop Δp l powered to −0.1. The radial profiles of D 32 widen with the increase in spill/feed ratio (SFR), but the ID 32 remain almost constant within the studied SFR range. The spray KE at closed spill line covers the droplet KE (21–26%) and that of entrained air (10–13%), both moderately varying with Δp l . The specific KEs of both the liquid and air markedly drop down with the spill line

Emission spectroscopy of argon ferrocene mixture jet in a low pressure plasma reactor

International Nuclear Information System (INIS)

Tiwari, N.; Tak, A.K.; Chakravarthy, Y.; Shukla, A.; Meher, K.C.; Ghorui, S.; Thiyagarajan, T.K.

2015-01-01

Emission spectroscopy is employed to measure the plasma temperature and species identification in a reactor used for studying homogenous nucleation and growth of iron nano particle. Reactor employs segmented non transferred plasma torch mounted on water cooled cylindrical chamber. The plasma jet passes through graphite nozzle and expands in low pressure reactor. Ferrocene is fed into the nozzle where it mixes with Argon plasma jet. A high resolution spectrograph (SHAMROCK 303i, resolution 0.06 nm) has been used to record the spectra over a wide range. Identification of different emission lines has been done using NIST database. Lines from (700 to 860nm) were considered for calculation of temperature. Spectra were recorded for different axial location, pressure and power. Temperature was calculated using Maxwell Boltzman plot method. Variation in temperature with pressure and location is presented and possible reasons for different behaviour are explored. (author)

Numerical Coupling of the Particulate Phase to the Plasma Phase in Modeling of Multi-Arc Plasma Spraying

International Nuclear Information System (INIS)

Bobzin, K.; Öte, M.

2017-01-01

Inherent to Euler-Lagrange formulation, which can be used in order to describe the particle behavior in plasma spraying, particle in-flight characteristics are determined by calculating the impulse, heat and mass transfer between the plasma jet and individual powder particles. Based on the assumption that the influence of the particulate phase on the fluid phase is insignificant, impulse, heat and mass transfer from particles to the plasma jet can be neglected using the so-called numerical approach of “one-way coupling”. On the other hand, so-called “two-way coupling” considers the two-sided transfer between both phases. The former is a common simplification used in the literature to describe the plasma-particle interaction in thermal spraying. This study focuses on the significance of this simplification on the calculated results and shows that the use of this simplification leads to significant errors in calculated plasma and particle in-flight characteristics in three-cathode plasma spraying process. (paper)

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

Suspension plasma sprayed composite coating using amorphous powder feedstock

International Nuclear Information System (INIS)

Chen Dianying; Jordan, Eric H.; Gell, Maurice

2009-01-01

Al 2 O 3 -ZrO 2 composite coatings were deposited by the suspension plasma spray process using molecularly mixed amorphous powders. X-ray diffraction (XRD) analysis shows that the as-sprayed coating is composed of α-Al 2 O 3 and tetragonal ZrO 2 phases with grain sizes of 26 nm and 18 nm, respectively. The as-sprayed coating has 93% density with a hardness of 9.9 GPa. Heat treatment of the as-sprayed coating reveals that the Al 2 O 3 and ZrO 2 phases are homogeneously distributed in the composite coating

Electrical properties of pressure quenched silicon by thermal spraying

International Nuclear Information System (INIS)

Tan, S.Y.; Gambino, R.J.; Sampath, S.; Herman, H.

2007-01-01

High velocity thermal spray deposition of polycrystalline silicon film onto single crystal substrates, yields metastable high pressure forms of silicon in nanocrystalline form within the deposit. The phases observed in the deposit include hexagonal diamond-Si, R-8, BC-8 and Si-IX. The peculiar attribute of this transformation is that it occurs only on orientation silicon substrate. The silicon deposits containing the high pressure phases display a substantially higher electrical conductivity. The resistivity profile of the silicon deposit containing shock induced metastable silicon phases identified by X-ray diffraction patterns. The density of the pressure induced polymorphic silicon is higher at deposit/substrate interface. A modified two-layer model is presented to explain the resistivity of the deposit impacted by the pressure induced polymorphic silicon generated by the thermal spraying process. The pressure quenched silicon deposits on the p - silicon substrate, with or without metastable phases, display the barrier potential of about 0.72 eV. The measured hall mobility value of pressure quenched silicon deposits is in the range of polycrystalline silicon. The significance of this work lies in the fact that the versatility of thermal spray may enable applications of these high pressure forms of silicon

Yb2Si2O7 Environmental Barrier Coatings Deposited by Various Thermal Spray Techniques: A Preliminary Comparative Study

Science.gov (United States)

Bakan, Emine; Marcano, Diana; Zhou, Dapeng; Sohn, Yoo Jung; Mauer, Georg; Vaßen, Robert

2017-08-01

Dense, crack-free, uniform, and well-adhered environmental barrier coatings (EBCs) are required to enhance the environmental durability of silicon (Si)-based ceramic matrix composites in high pressure, high gas velocity combustion atmospheres. This paper represents an assessment of different thermal spray techniques for the deposition of Yb2Si2O7 EBCs. The Yb2Si2O7 coatings were deposited by means of atmospheric plasma spraying (APS), high-velocity oxygen fuel spraying (HVOF), suspension plasma spraying (SPS), and very low-pressure plasma spraying (VLPPS) techniques. The initial feedstock, as well as the deposited coatings, were characterized and compared in terms of their phase composition. The as-sprayed amorphous content, microstructure, and porosity of the coatings were further analyzed. Based on this preliminary investigation, the HVOF process stood out from the other techniques as it enabled the production of vertical crack-free coatings with higher crystallinity in comparison with the APS and SPS techniques in atmospheric conditions. Nevertheless, VLPPS was found to be the preferred process for the deposition of Yb2Si2O7 coatings with desired characteristics in a controlled-atmosphere chamber.

Current Progress in Solution Precursor Plasma Spraying of Cermets: A Review

Directory of Open Access Journals (Sweden)

Romnick Unabia

2018-06-01

Full Text Available Ceramic and metal composites, known also as cermets, may considerably improve many material properties with regards to that of initial components. Hence, cermets are frequently applied in many technological fields. Among many processes which can be employed for cermet manufacturing, thermal spraying is one of the most frequently used. Conventional plasma spraying of powders is a popular and cost-effective manufacturing process. One of its most recent innovations, called solution precursor plasma spraying (SPPS, is an emerging coating deposition method which uses homogeneously mixed solution precursors as a feedstock. The technique enables a single-step deposition avoiding the powder preparation procedures. The nanostructured coatings developed by SPPS increasingly find a place in the field of surface engineering. The present review shows the recent progress in the fabrication of cermets using SPPS. The influence of starting solution precursors, such as their chemistry, concentration, and solvents used, to the micro-structural characteristics of cermet coatings is discussed. The effect of the operational plasma spray process parameters such as solution injection mode to the deposition process and coatings’ microstructure is also presented. Moreover, the advantages of the SPPS process and its drawbacks compared to the conventional powder plasma spraying process are discussed. Finally, some applications of SPPS cermet coatings are presented to understand the potential of the process.

Deposition of Lanthanum Strontium Cobalt Ferrite (LSCF) Using Suspension Plasma Spraying for Oxygen Transport Membrane Applications

Science.gov (United States)

Fan, E. S. C.; Kesler, O.

2015-08-01

Suspension plasma spray deposition was utilized to fabricate dense lanthanum strontium cobalt ferrite oxygen separation membranes (OSMs) on porous metal substrates for mechanical support. The as-sprayed membranes had negligible and/or reversible material decomposition. At the longer stand-off distance (80 mm), smooth and dense membranes could be manufactured using a plasma with power below approximately 81 kW. Moreover, a membrane of 55 μm was observed to have very low gas leakage rates desirable for OSM applications. This thickness could potentially be decreased further to improve oxygen diffusion by using metal substrates with finer surface pores.

Characterization of metal-supported axial injection plasma sprayed solid oxide fuel cells with aqueous suspension plasma sprayed electrolyte layers

Science.gov (United States)

Waldbillig, D.; Kesler, O.

A method for manufacturing metal-supported SOFCs with atmospheric plasma spraying (APS) is presented, making use of aqueous suspension feedstock for the electrolyte layer and dry powder feedstock for the anode and cathode layers. The cathode layer was deposited first directly onto a metal support, in order to minimize contact resistance, and to allow the introduction of added porosity. The electrolyte layers produced by suspension plasma spraying (SPS) were characterized in terms of thickness, permeability, and microstructure, and the impact of substrate morphology on electrolyte properties was investigated. Fuel cells produced by APS were electrochemically tested at temperatures ranging from 650 to 750 °C. The substrate morphology had little effect on open circuit voltage, but substrates with finer porosity resulted in lower kinetic losses in the fuel cell polarization.

Characterization of metal-supported axial injection plasma sprayed solid oxide fuel cells with aqueous suspension plasma sprayed electrolyte layers

Energy Technology Data Exchange (ETDEWEB)

Waldbillig, D. [University of British Columbia, Department of Materials Engineering, 309-6350 Stores Road, Vancouver, BC (Canada); Kesler, O. [University of Toronto, Department of Mechanical and Industrial Engineering, 5 King' s College Road, Toronto, Ontario (Canada)

2009-06-15

A method for manufacturing metal-supported SOFCs with atmospheric plasma spraying (APS) is presented, making use of aqueous suspension feedstock for the electrolyte layer and dry powder feedstock for the anode and cathode layers. The cathode layer was deposited first directly onto a metal support, in order to minimize contact resistance, and to allow the introduction of added porosity. The electrolyte layers produced by suspension plasma spraying (SPS) were characterized in terms of thickness, permeability, and microstructure, and the impact of substrate morphology on electrolyte properties was investigated. Fuel cells produced by APS were electrochemically tested at temperatures ranging from 650 to 750 C. The substrate morphology had little effect on open circuit voltage, but substrates with finer porosity resulted in lower kinetic losses in the fuel cell polarization. (author)

Development of Process for Plasma Spray:Case Study for Molybdenum

Czech Academy of Sciences Publication Activity Database

Sampath, S.; Jiang, X.; Kulkarni, A.; Matějíček, Jiří; Gilmore, D. L.; Neiser, R. A.

2003-01-01

Roč. 348, 1-2 (2003), s. 54-66 ISSN 0921-5093 Grant - others:NSF(US) DMR9632570 Institutional research plan: CEZ:AV0Z2043910 Keywords : process maps, plasma spray, thermal spray Subject RIV: JG - Metallurgy Impact factor: 1.365, year: 2003

Spray structure of a pressure-swirl atomizer for combustion applications

Directory of Open Access Journals (Sweden)

Jicha Miroslav

2012-04-01

Full Text Available In the present work, global as well as spatially resolved parameters of a spray produced by a pressure-swirl atomizer are obtained. Small pressure-swirl atomizer for aircraft combustion chambers was run on a newly designed test bench with Jet A-1 kerosene type aviation fuel. The atomizer was tested in four regimes based on typical operation conditions of the engine. Spray characteristics were studied using two optical measurement systems, Particle Image velocimetry (PIV and Phase-Doppler Particle Analyzer (P/DPA. The results obtained with P/DPA include information about Sauter Mean Diameter of droplets and spray velocity profiles in one plane perpendicular to the spray axis. Velocity magnitudes of droplets in an axial section of the spray were obtained using PIV. The experimental outputs also show a good confirmation of velocity profiles obtained with both instruments in the test plane. These data together will elucidate impact of the spray quality on the whole combustion process, its efficiency and exhaust gas emissions.

Spray structure of a pressure-swirl atomizer for combustion applications

Science.gov (United States)

Durdina, Lukas; Jedelsky, Jan; Jicha, Miroslav

2012-04-01

In the present work, global as well as spatially resolved parameters of a spray produced by a pressure-swirl atomizer are obtained. Small pressure-swirl atomizer for aircraft combustion chambers was run on a newly designed test bench with Jet A-1 kerosene type aviation fuel. The atomizer was tested in four regimes based on typical operation conditions of the engine. Spray characteristics were studied using two optical measurement systems, Particle Image velocimetry (PIV) and Phase-Doppler Particle Analyzer (P/DPA). The results obtained with P/DPA include information about Sauter Mean Diameter of droplets and spray velocity profiles in one plane perpendicular to the spray axis. Velocity magnitudes of droplets in an axial section of the spray were obtained using PIV. The experimental outputs also show a good confirmation of velocity profiles obtained with both instruments in the test plane. These data together will elucidate impact of the spray quality on the whole combustion process, its efficiency and exhaust gas emissions.

Partial-depth modulation study of anions and neutrals in low pressure silane plasmas

International Nuclear Information System (INIS)

Cozurteille, C.; Dorier, J.L.; Hollenstein, C.; Sansonnens; Howling, A.A.

1995-10-01

Partial-depth modulation of the rf power in a capacitive discharge is used to investigate the relative importance of negative ions and neutral radicals for particle formation in low power, low pressure silane plasmas. For less than 85% modulation depth, anions are trapped indefinitely in the plasma and particle formation ensues, whereas the polymerised neutral flux magnitudes and dynamics are independent of the modulation depth and the powder formation. These observations suggest that negative ions could be the particle precursors in plasma conditions where powder appears many seconds after plasma ignition. Microwave interferometry and mass spectrometry were combined to infer an anion density of ≅7.10 9 cm -3 which is approximately twice the free electron density in these modulated plasmas. (author) 6 figs., tabs., refs

On the parallel momentum balance in low pressure plasmas with an inhomogeneous magnetic field

International Nuclear Information System (INIS)

Smolyakov, A.I.; Garbet, X.; Bourdelle, C.

2009-01-01

This paper describes the structure of the parallel momentum balance in low pressure plasmas with an inhomogeneous magnetic field. The parallel momentum balance equation is derived from magnetohydrodynamic equations by an expansion in the inverse magnetic field 1/B as a small parameter. Contributions of the gyroviscosity and inertia terms are clarified. It is shown that magnetic field curvature leads to important coupling of parallel flow with fluctuations of the electric field and plasma pressure.

Surface chemical structure of poly(ethylene naphthalate) films during degradation in low-pressure high-frequency plasma treatments

Science.gov (United States)

Kamata, Noritsugu; Yuji, Toshifumi; Thungsuk, Nuttee; Arunrungrusmi, Somchai; Chansri, Pakpoom; Kinoshita, Hiroyuki; Mungkung, Narong

2018-06-01

The surface chemical structure of poly(ethylene naphthalate) (PEN) films treated with a low-pressure, high-frequency plasma was investigated by storing in a box at room temperature to protect the PEN film surface from dust. The functional groups on the PEN film surface changed over time. The functional groups of –C=O, –COH, and –COOH were abundant in the Ar + O2 mixture gas plasma-treated PEN samples as compared with those in untreated PEN samples. The changes occurred rapidly after 2 d following the plasma treatment, reaching steady states 8 d after the treatment. Hydrophobicity had an inverse relationship with the concentration of these functional groups on the surface. Thus, the effect of the low-pressure high-frequency plasma treatment on PEN varies as a function of storage time. This means that radical oxygen and oxygen molecules are clearly generated in the plasma, and this is one index to confirm that radical reaction has definitely occurred between the gas and the PEN film surface with a low-pressure high-frequency plasma.

Synthesis and Characterization of Calcium Phosphate Powders for Biomedical Applications by Plasma Spray Coating

OpenAIRE

Sasidharan Pillai, Rahul

2015-01-01

This PhD work mainly focus on the synthesis and characterization of calcium phosphate powders for plasma spray coating. The preparation of high temperature phase stabilized βTCP and HA/βTCP powders for plasma spray coating applications has been the topic of investigation. Nowadays plasma sprayed coatings are widely used for biomedical applications especially in the dental and orthopaedic implantation field. Previously Ti based alloys were widely used for the orthopaedic and dental implant ap...

Modeling of low pressure plasma sources for microelectronics fabrication

International Nuclear Information System (INIS)

Agarwal, Ankur; Bera, Kallol; Kenney, Jason; Rauf, Shahid; Likhanskii, Alexandre

2017-01-01

Chemically reactive plasmas operating in the 1 mTorr–10 Torr pressure range are widely used for thin film processing in the semiconductor industry. Plasma modeling has come to play an important role in the design of these plasma processing systems. A number of 3-dimensional (3D) fluid and hybrid plasma modeling examples are used to illustrate the role of computational investigations in design of plasma processing hardware for applications such as ion implantation, deposition, and etching. A model for a rectangular inductively coupled plasma (ICP) source is described, which is employed as an ion source for ion implantation. It is shown that gas pressure strongly influences ion flux uniformity, which is determined by the balance between the location of plasma production and diffusion. The effect of chamber dimensions on plasma uniformity in a rectangular capacitively coupled plasma (CCP) is examined using an electromagnetic plasma model. Due to high pressure and small gap in this system, plasma uniformity is found to be primarily determined by the electric field profile in the sheath/pre-sheath region. A 3D model is utilized to investigate the confinement properties of a mesh in a cylindrical CCP. Results highlight the role of hole topology and size on the formation of localized hot-spots. A 3D electromagnetic plasma model for a cylindrical ICP is used to study inductive versus capacitive power coupling and how placement of ground return wires influences it. Finally, a 3D hybrid plasma model for an electron beam generated magnetized plasma is used to understand the role of reactor geometry on plasma uniformity in the presence of E  ×  B drift. (paper)

Modeling of low pressure plasma sources for microelectronics fabrication

Science.gov (United States)

Agarwal, Ankur; Bera, Kallol; Kenney, Jason; Likhanskii, Alexandre; Rauf, Shahid

2017-10-01

Chemically reactive plasmas operating in the 1 mTorr-10 Torr pressure range are widely used for thin film processing in the semiconductor industry. Plasma modeling has come to play an important role in the design of these plasma processing systems. A number of 3-dimensional (3D) fluid and hybrid plasma modeling examples are used to illustrate the role of computational investigations in design of plasma processing hardware for applications such as ion implantation, deposition, and etching. A model for a rectangular inductively coupled plasma (ICP) source is described, which is employed as an ion source for ion implantation. It is shown that gas pressure strongly influences ion flux uniformity, which is determined by the balance between the location of plasma production and diffusion. The effect of chamber dimensions on plasma uniformity in a rectangular capacitively coupled plasma (CCP) is examined using an electromagnetic plasma model. Due to high pressure and small gap in this system, plasma uniformity is found to be primarily determined by the electric field profile in the sheath/pre-sheath region. A 3D model is utilized to investigate the confinement properties of a mesh in a cylindrical CCP. Results highlight the role of hole topology and size on the formation of localized hot-spots. A 3D electromagnetic plasma model for a cylindrical ICP is used to study inductive versus capacitive power coupling and how placement of ground return wires influences it. Finally, a 3D hybrid plasma model for an electron beam generated magnetized plasma is used to understand the role of reactor geometry on plasma uniformity in the presence of E  ×  B drift.

Aligned, plasma sprayed SmCo5 deposits

International Nuclear Information System (INIS)

Kumar, K.; Das, D.

1986-01-01

Highly aligned SmCo 5 deposits were produced using plasma spraying. c-axis alignment, normal to the plane of the deposit, was achieved by depositing the Sm-Co alloys on steel substrates maintained at high temperatures. The substrates were heated by the plasma flame to obtain the high temperatures. The attainment of a range of substrate temperatures was made possible through control over the geometry of the substrate

Dielectric properties of plasma sprayed silicates

Czech Academy of Sciences Publication Activity Database

Ctibor, Pavel; Sedláček, J.; Neufuss, Karel; Dubský, Jiří; Chráska, Pavel

-, č. 31 (2005), s. 315-321 ISSN 0272-8842 R&D Projects: GA ČR(CZ) GA202/03/0708 Institutional research plan: CEZ:AV0Z20430508 Keywords : Optical microscopy * electrical properties * silicates * insulators * plasma spraying Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.702, year: 2005

Atmospheric-pressure plasma jet

Science.gov (United States)

Selwyn, Gary S.

1999-01-01

Atmospheric-pressure plasma jet. A .gamma.-mode, resonant-cavity plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two concentric cylindrical electrodes are employed to generate a plasma in the annular region therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly shaping the rf-powered electrode. Because of the atmospheric pressure operation, no ions survive for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike low-pressure plasma sources and conventional plasma processing methods.

Data needs for diagnostics of low pressure plasmas

International Nuclear Information System (INIS)

Graham, Bill

2000-01-01

The low pressure plasma processing environment is complex and presents many diagnostic challenges. Here the diagnostic techniques used for accurate and detailed measurement of the density and energy distributions of charged and neutral species are reviewed. Most of the techniques rely heavily on atomic and molecular data. The specific data needs of each diagnostic are outlined. It is shown that in total these data needs are vast and diverse and cannot all be met from specific measurements or calculations. The real need is for generic scaling rules for each of the significant atomic and molecular processes

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

OpenAIRE

D. Thirumalaikumarasamy; K. Shanmugam; V. Balasubramanian

2014-01-01

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 w...

Deposition of titanium nitride layers by electric arc – Reactive plasma spraying method

International Nuclear Information System (INIS)

Şerban, Viorel-Aurel; Roşu, Radu Alexandru; Bucur, Alexandra Ioana; Pascu, Doru Romulus

2013-01-01

Highlights: ► Titanium nitride layers deposited by electric arc – reactive plasma spraying method. ► Deposition of titanium nitride layers on C45 steel at different spraying distances. ► Characterization of the coatings hardness as function of the spraying distances. ► Determination of the corrosion behavior of titanium nitride layers obtained. - Abstract: Titanium nitride (TiN) is a ceramic material which possesses high mechanical properties, being often used in order to cover cutting tools, thus increasing their lifetime, and also for covering components which are working in corrosive environments. The paper presents the experimental results on deposition of titanium nitride coatings by a new combined method (reactive plasma spraying and electric arc thermal spraying). In this way the advantages of each method in part are combined, obtaining improved quality coatings in the same time achieving high productivity. Commercially pure titanium wire and C45 steel as substrate were used for experiments. X-ray diffraction analysis shows that the deposited coatings are composed of titanium nitride (TiN, Ti 2 N) and small amounts of Ti 3 O. The microstructure of the deposited layers, investigated both by optical and scanning electron microscopy, shows that the coatings are dense, compact, without cracks and with low porosity. Vickers microhardness of the coatings presents maximum values of 912 HV0.1. The corrosion tests in 3%NaCl solution show that the deposited layers have a high corrosion resistance compared to unalloyed steel substrate.

Effect of laser induced plasma ignition timing and location on Diesel spray combustion

International Nuclear Information System (INIS)

Pastor, José V.; García-Oliver, José M.; García, Antonio; Pinotti, Mattia

2017-01-01

Highlights: • Laser plasma ignition is applied to a direct injection Diesel spray, compared with auto-ignition. • Critical local fuel/air ratio for LIP provoked ignition is obtained. • The LIP system is able to stabilize Diesel combustion compared to auto-ignition cases. • Varying LIP position along spray axis directly affects Ignition-delay. • Premixed combustion is reduced both by varying position and delay of the LIP ignition system. - Abstract: An experimental study about the influence of the local conditions at the ignition location on combustion development of a direct injection spray is carried out in an optical engine. A laser induced plasma ignition system has been used to force the spray ignition, allowing comparison of combustion’s evolution and stability with the case of conventional autoignition on the Diesel fuel in terms of ignition delay, rate of heat release, spray penetration and soot location evolution. The local equivalence ratio variation along the spray axis during the injection process was determined with a 1D spray model, previously calibrated and validated. Upper equivalence ratios limits for the ignition event of a direct injected Diesel spray, both in terms of ignition success possibilities and stability of the phenomena, could been determined thanks to application of the laser plasma ignition system. In all laser plasma induced ignition cases, heat release was found to be higher than for the autoignition reference cases, and it was found to be linked to a decrease of ignition delay, with the premixed peak in the rate of heat release curve progressively disappearing as the ignition delay time gets shorter. Ignition delay has been analyzed as a function of the laser position, too. It was found that ignition delay increases for plasma positions closer to the nozzle, indicating that the amount of energy introduced by the laser induced plasma is not the only parameter affecting combustion initiation, but local equivalence ratio

Dielectric and mechanical properties of plasma-sprayed olivine

Czech Academy of Sciences Publication Activity Database

Ctibor, Pavel; Neufuss, Karel; Pala, Zdeněk; Kotlan, Jiří; Soumar, J.

2015-01-01

Roč. 67, č. 2 (2015), s. 600-616 ISSN 1221-1451. [International Conference on Plasma Physics and Applications/16./. Magurele, Bucharest, 20.06.2013-25.06.2013] Institutional support: RVO:61389021 Keywords : olivine * plasma spraying * dielectric properties Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.367, year: 2015 www.infim.ro/rrp

The spray-drying process is sufficient to inactivate infectious porcine epidemic diarrhea virus in plasma.

Science.gov (United States)

Gerber, Priscilla F; Xiao, Chao-Ting; Chen, Qi; Zhang, Jianqiang; Halbur, Patrick G; Opriessnig, Tanja

2014-11-07

Porcine epidemic diarrhea virus (PEDV) is considered an emergent pathogen associated with high economic losses in many pig rearing areas. Recently it has been suggested that PEDV could be transmitted to naïve pig populations through inclusion of spray-dried porcine plasma (SDPP) into the nursery diet which led to a ban of SDPP in several areas in North America and Europe. To determine the effect of spray-drying on PEDV infectivity, 3-week-old pigs were intragastrically inoculated with (1) raw porcine plasma spiked with PEDV (RAW-PEDV-CONTROL), (2) porcine plasma spiked with PEDV and then spray dried (SD-PEDV-CONTROL), (3) raw plasma from PEDV infected pigs (RAW-SICK), (4) spray-dried plasma from PEDV infected pigs (SD-SICK), or (5) spray-dried plasma from PEDV negative pigs (SD-NEG-CONTROL). For the spray-drying process, a tabletop spray-dryer with industry-like settings for inlet and outlet temperatures was used. In the RAW-PEDV-CONTROL group, PEDV RNA was present in feces at day post infection (dpi) 3 and the pigs seroconverted by dpi 14. In contrast, PEDV RNA in feces was not detected in any of the pigs in the other groups including the SD-PEDV-CONTROL group and none of the pigs had seroconverted by termination of the project at dpi 28. This work provides direct evidence that the experimental spray-drying process used in this study was effective in inactivating infectious PEDV in the plasma. Additionally, plasma collected from PEDV infected pigs at peak disease did not contain infectious PEDV. These findings suggest that the risk for PEDV transmission through commercially produced SDPP is minimal. Copyright © 2014 Elsevier B.V. All rights reserved.

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)

Characterization of Plasma Sprayed Beryllium ITER First Wall Mockups

International Nuclear Information System (INIS)

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

1997-10-01

ITER first wall beryllium mockups, which were fabricated by vacuum plasma spraying the beryllium armor, have survived 3000 thermal fatigue cycles at 1 MW/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

“Virtual IED sensor” at an rf-biased electrode in low-pressure plasma

Energy Technology Data Exchange (ETDEWEB)

Bogdanova, M. A.; Zyryanov, S. M. [Skobeltsyn Institute of Nuclear Physics, Moscow State University, SINP MSU, Moscow (Russian Federation); Faculty of Physics, Moscow State University, MSU, Moscow (Russian Federation); Lopaev, D. V.; Rakhimov, A. T. [Skobeltsyn Institute of Nuclear Physics, Moscow State University, SINP MSU, Moscow (Russian Federation)

2016-07-15

Energy distribution and the flux of the ions coming on a surface are considered as the key-parameters in anisotropic plasma etching. Since direct ion energy distribution (IED) measurements at the treated surface during plasma processing are often hardly possible, there is an opportunity for virtual ones. This work is devoted to the possibility of such indirect IED and ion flux measurements at an rf-biased electrode in low-pressure rf plasma by using a “virtual IED sensor” which represents “in-situ” IED calculations on the absolute scale in accordance with a plasma sheath model containing a set of measurable external parameters. The “virtual IED sensor” should also involve some external calibration procedure. Applicability and accuracy of the “virtual IED sensor” are validated for a dual-frequency reactive ion etching (RIE) inductively coupled plasma (ICP) reactor with a capacitively coupled rf-biased electrode. The validation is carried out for heavy (Ar) and light (H{sub 2}) gases under different discharge conditions (different ICP powers, rf-bias frequencies, and voltages). An EQP mass-spectrometer and an rf-compensated Langmuir probe (LP) are used to characterize plasma, while an rf-compensated retarded field energy analyzer (RFEA) is applied to measure IED and ion flux at the rf-biased electrode. Besides, the pulsed selfbias method is used as an external calibration procedure for ion flux estimating at the rf-biased electrode. It is shown that pulsed selfbias method allows calibrating the IED absolute scale quite accurately. It is also shown that the “virtual IED sensor” based on the simplest collisionless sheath model allows reproducing well enough the experimental IEDs at the pressures when the sheath thickness s is less than the ion mean free path λ{sub i} (s < λ{sub i}). At higher pressure (when s > λ{sub i}), the difference between calculated and experimental IEDs due to ion collisions in the sheath is observed in the low

Properties of tungsten coating deposited onto copper by high-speed atmospheric plasma spraying

Energy Technology Data Exchange (ETDEWEB)

Huang Jianjun, E-mail: huangjj@szu.edu.cn [Applied Low Temperature Plasma Laboratory, College of Physics Science and Technology, Shenzhen University, Shenzhen 518060 (China); Wang Fan; Liu Ying; Jiang Shishou; Wang Xisheng; Qi Bing; Gao Liang [Applied Low Temperature Plasma Laboratory, College of Physics Science and Technology, Shenzhen University, Shenzhen 518060 (China)

2011-07-01

Tungsten (W) coatings were fabricated on copper (Cu) by high-speed atmospheric plasma spray (HAPS) technique. The properties of the porosity, oxygen content, bonding strength and microhardness were measured. The results obtained indicated that the HAPS-W coating showed good properties particularly in terms of porosity and oxygen content. The porosity of the HAPS-W coating was 2.3% and the distribution of pore size diameter was mainly concentrated in the range of 0.01-1 {mu}m. The oxygen content of the coating measured by means of Nitrogen/Oxygen Determinator was about 0.10 wt.%. These initial results suggest that the HAPS-W coating has achieved the reported properties of the vacuum plasma spray (VPS) W coating. Compared with VPS, HAPS-W technique could provide a convenient and low cost way to obtain adequate W coatings for fusion applications.

Highly ionized physical vapor deposition plasma source working at very low pressure

Czech Academy of Sciences Publication Activity Database

Straňák, V.; Herrendorf, A.-P.; Drache, S.; Čada, Martin; Hubička, Zdeněk; Tichý, M.; Hippler, R.

2012-01-01

Roč. 100, č. 14 (2012), "141604-1"-"141604-3" ISSN 0003-6951 R&D Projects: GA TA ČR TA01010517; GA ČR(CZ) GAP205/11/0386; GA ČR GAP108/12/1941 Institutional research plan: CEZ:AV0Z10100522 Keywords : magnetron * ECWR * low-pressure * sputtering * plasma diagnostics Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.794, year: 2012 http://dx.doi.org/10.1063/1.3699229

Simulation of rarefied low pressure RF plasma flow around the sample

Science.gov (United States)

Zheltukhin, V. S.; Shemakhin, A. Yu

2017-01-01

The paper describes a mathematical model of the flow of radio frequency plasma at low pressure. The hybrid mathematical model includes the Boltzmann equation for the neutral component of the RF plasma, the continuity and the thermal equations for the charged component. Initial and boundary conditions for the corresponding equations are described. The electron temperature in the calculations is 1-4 eV, atoms temperature in the plasma clot is (3-4) • 103 K, in the plasma jet is (3.2-10) • 102 K, the degree of ionization is 10-7-10-5, electron density is 1015-1019 m-3. For calculations plasma parameters is developed soft package on C++ program language, that uses the OpenFOAM library package. Simulations for the vacuum chamber in the presence of a sample and the free jet flow were carried out.

Physico-chemical characteristics of high performance polymer modified by low and atmospheric pressure plasma

International Nuclear Information System (INIS)

Bhatnagar, Nitu; Sangeeta, Jha; Bhowmik, Shantanu; Gupta, Govind; Moon, J.B.; Kim, C.G.

2012-01-01

In this work, the effect of low pressure plasma and atmospheric p ressure plasma treatment on surface properties and adhesion characteristics of high performance polymer, Polyether Ether Ketone (PEEK) are investigated in terms of Fourier Transform Infrared Spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and Atomic Force Microscopy (AFM). The experimental results show that the PEEK surface treated by atmospheric pressure plasma lead to an increase in the polar component of the surface energy, resulting in improving the adhesion characteristics of the PEEK/Epoxy adhesive system. Also, the roughness of the treated surfaces is largely increased as confirmed by AFM observation. These results can be explained by the fact that the atmospheric pressure plasma treatment of PEEK surface yields several oxygen functionalities on hydrophobic surface, which play an important role in increasing the surface polarity, wettability, and the adhesion characteristics of the PEEK/Epoxy adhesive system. (authors)

Comparison of W–TiC composite coatings fabricated by atmospheric plasma spraying and supersonic atmospheric plasma spraying

International Nuclear Information System (INIS)

Hou, Qing Yu; Luo, Lai Ma; Huang, Zhen Yi; Wang, Ping; Ding, Ting Ting; Wu, Yu Cheng

2016-01-01

Highlights: • W–TiC composite coatings were fabricated by APS and SAPS technologies. • TiC had filling effect on pores and coating/fixing effect on un-melted particles. • Porosity and oxygen content in SAPS coating were lower than that in APS coating. • Thermal conductivity of SAPS coating was higher than that of APS coating. • SAPS coating has better ability to resist to elastic fracture than APS coating does. - Abstract: Tungsten coatings with 1.5 wt.% TiC (W/TiC) were fabricated by atmospheric plasma spraying (APS) and supersonic atmospheric plasma spraying (SAPS) techniques, respectively. The results showed that the typical lamellar structure of plasma spraying and columnar crystalline grains formed in the coatings. Pores located mainly at lamellar gaps in association with oxidation were also observed. TiC phase, distributed at lamellar gaps filled the gaps; and that distributed around un-melted tungsten particles and splashed debris coated the particles or debris that were linked with the TiC at lamellar gaps. The coating and linking of the retained TiC phase prevented the tungsten particles to come off from the coatings. The porosity and the oxygen content of the SAPS-W/TiC were lower than those of the APS-W/TiC coating. The mechanical response of the coatings was strongly dependent on the H/E* ratio (H and E* are the hardness and effective Young’s modulus, respectively). The SAPS-W/TiC coating with a higher H/E* ratio had a better ability to resist to elastic fracture and better fracture toughness as compared with the APS-W/TiC coating with a smaller H/E* ratio. The thermal conductivity of the SAPS-W/TiC coating was greater than that of the APS-W/TiC coating.

E-H mode transition in low-pressure inductively coupled nitrogen-argon and oxygen-argon plasmas

International Nuclear Information System (INIS)

Lee, Young Wook; Lee, Hye Lan; Chung, T. H.

2011-01-01

This work investigates the characteristics of the E-H mode transition in low-pressure inductively coupled N 2 -Ar and O 2 -Ar discharges using rf-compensated Langmuir probe measurements and optical emission spectroscopy (OES). As the ICP power increases, the emission intensities from plasma species, the electron density, the electron temperature, and the plasma potential exhibit sudden changes. The Ar content in the gas mixture and total gas pressure have been varied in an attempt to fully characterize the plasma parameters. With these control parameters varying, the changes of the transition threshold power and the electron energy distribution function (EEDF) are explored. In N 2 -Ar and O 2 -Ar discharges at low-pressures of several millitorr, the transition thresholds are observed to decrease with Ar content and pressure. It is observed that in N 2 -Ar plasmas during the transition, the shape of the EEDF changes from an unusual distribution with a flat hole near the electron energy of 3 eV in the E mode to a Maxwellian distribution in the H mode. However, in O 2 -Ar plasmas, the EEDFs in the E mode at low Ar contents show roughly bi-Maxwellian distributions, while the EEDFs in the H mode are observed to be nearly Maxwellian. In the E and H modes of O 2 -Ar discharges, the dissociation fraction of O 2 molecules is estimated using optical emission actinometry. During the E-H mode transition, the dissociation fraction of molecules is also enhanced.

Microstructure and mechanical properties of plasma sprayed Al2O3 – 13%TiO2 Ceramic Coating

Directory of Open Access Journals (Sweden)

Wahab Juyana A

2017-01-01

Full Text Available This paper focused on the effect of deposition conditions on the microstructural and mechanical properties of the ceramic coating. In this study, Al2O3 – 13%TiO2 coated mild steel were prepared by using atmospheric plasma spray technology with different plasma power ranging from 25 kW to 40 kW. The as-sprayed coatings consist of γ-Al2O3 phase as the major phase and small amount of the titania phase existed in the coating structure. High degree of fully melted region was observed in the surface morphology for the coating sprayed with high plasma power, which lead to the high hardness and low percentage of porosity. In this study, nanoindentation test was carried out to investigate mechanical properties of the coating and the results showed that the coatings possess high elastic behaviour, which beneficial in engineering practice.

Controlling of Nitriding Process on Reactive Plasma Spraying of Al Particles

International Nuclear Information System (INIS)

Shahien, Mohammed; Yamada, Motohiro; Yasui, Toshiaki; Fukumoto, Masahiro

2011-01-01

Reactive plasma spraying (RPS) has been considered as a promising technology for in-situ formation of aluminum nitride (AlN) thermally sprayed coatings. To fabricate thick A lN coatings in RPS process, controlling and improving the in-flight nitriding reaction of Al particles is required. In this study, it was possible to control the nitriding reaction by using ammonium chloride (NH 4 Cl) powders. Thick and dense AlN coating (more than 300 μm thickness) was successfully fabricated with small addition of NH 4 Cl powders. Thus, addition of NH 4 Cl prevented the Al aggregation by changing the reaction pathway to a mild way with no explosive mode (relatively low heating rates) and it acts as a catalyst, nitrogen source and diluent agent.

Erosion protection of carbon-epoxy composites by plasma-sprayed coatings

International Nuclear Information System (INIS)

Alonso, F.; Fagoaga, I.; Oregui, P.

1991-01-01

This paper deals with the production of plasma-sprayed erosion-resistant coatings on carbon-fibre - epoxy composites, and the study of their erosion behaviour. The heat sensitivity of the composite substrate requires a specific spraying procedure in order to avoid its degradation. In addition, several bonding layers were studied to allow spraying of the protective coatings. Two different functional coatings were sprayed onto an aluminium-glass bonding layer, a WC-12Co cermet and an Al 2 O 3 ceramic oxide. The microstructure and properties of these coatings were studied and their erosion behaviour determined experimentally in an erosion-testing device. (orig.)

Plasma Sprayed Tungsten-based Coatings and their Usage in Edge Plasma Region of Tokamaks

Czech Academy of Sciences Publication Activity Database

Matějíček, Jiří; Weinzettl, Vladimír; Dufková, Edita; Piffl, Vojtěch; Peřina, Vratislav

2006-01-01

Roč. 51, č. 2 (2006), s. 179-191 ISSN 0001-7043 Grant - others:Evropská unie EFDA Task TW-5-TVM-PSW (EU – Euratom) Institutional research plan: CEZ:AV0Z20430508; CEZ:AV0Z10480505 Keywords : plasma sprayed coatings * fusion * plasma facing components * tungsten * tokamak Subject RIV: BL - Plasma and Gas Discharge Physics

Tribological Behavior of Plasma-Sprayed Al2O3-20 wt.%TiO2 Coating

Science.gov (United States)

Cui, Shiyu; Miao, Qiang; Liang, Wenping; Zhang, Zhigang; Xu, Yi; Ren, Beilei

2017-05-01

Al2O3-20 wt.% TiO2 ceramic coatings were deposited on the surface of Grade D steel by plasma spraying of commercially available powders. The phases and the microstructures of the coatings were investigated by x-ray diffraction and scanning electron microscopy, respectively. The Al2O3-20 wt.% TiO2 composite coating exhibited a typical inter-lamellar structure consisting of the γ-Al2O3 and the Al2TiO5 phases. The dry sliding wear behavior of the coating was examined at 20 °C using a ball-on-disk wear tester. The plasma-sprayed coating showed a low wear rate ( 4.5 × 10-6 mm3 N-1 m-1), which was matrix ( 283.3 × 10-6 mm3 N-1 m-1), under a load of 15 N. In addition, the tribological behavior of the plasma-sprayed coating was analyzed by examining the microstructure after the wear tests. It was found that delamination of the Al2TiO5 phase was the main cause of the wear during the sliding wear tests. A suitable model was used to simulate the wear mechanism of the coating.

Studies on Microscopic Structure of Diesel Sprays under Atmospheric and High Gas Pressures

Directory of Open Access Journals (Sweden)

D. Deshmukh

2014-06-01

Full Text Available In the present work, the spray structure of diesel from a 200-μm, single-hole solenoid injector is studied using microscopic imaging at injection pressures of 700, 1000 and 1400 bar for various gas pressures. A long-distance microscope with a high resolution camera is used for spray visualization with a direct imaging technique. This study shows that even at very high injection pressures, the spray structure in an ambient environment of atmospheric pressure reveals presence of entangled ligaments and non-spherical droplets during the injection period. With increase in the injection pressure, the ligaments tend to get smaller and spread radially. The spray structure studies are also conducted at high gas pressures in a specially designed high pressure chamber with optical access. The near nozzle spray structure at the end of the injection shows that the liquid jet breakup is improved with increase in gas density. The droplet size measurement is possible only late in the injection duration when the breakup appears to be complete and mostly spherical droplets are observed. Hence, droplet size measurements are performed after 1.3 ms from start of the injection pulse. Spatial and temporal variation in Sauter Mean Diameter (SMD is observed and reported for the case corresponding to an injection pressure of 700 bar. Overall, this study has highlighted the importance of verifying the extentof atomization and droplet shape even in dense sprays before using conventional dropsizing methods such as PDPA.

Simulation of rarefied low pressure RF plasma flow around the sample

International Nuclear Information System (INIS)

Zheltukhin, V S; Shemakhin, A Yu

2017-01-01

The paper describes a mathematical model of the flow of radio frequency plasma at low pressure. The hybrid mathematical model includes the Boltzmann equation for the neutral component of the RF plasma, the continuity and the thermal equations for the charged component. Initial and boundary conditions for the corresponding equations are described. The electron temperature in the calculations is 1-4 eV, atoms temperature in the plasma clot is (3-4) • 10 3 K, in the plasma jet is (3.2-10) • 10 2 K, the degree of ionization is 10 -7 -10 -5 , electron density is 10 15 -10 19 m -3 . For calculations plasma parameters is developed soft package on C++ program language, that uses the OpenFOAM library package. Simulations for the vacuum chamber in the presence of a sample and the free jet flow were carried out. (paper)

Atmospheric Pressure Plasma Jet-Assisted Synthesis of Zeolite-Based Low-k Thin Films.

Science.gov (United States)

Huang, Kai-Yu; Chi, Heng-Yu; Kao, Peng-Kai; Huang, Fei-Hung; Jian, Qi-Ming; Cheng, I-Chun; Lee, Wen-Ya; Hsu, Cheng-Che; Kang, Dun-Yen

2018-01-10

Zeolites are ideal low-dielectric constant (low-k) materials. This paper reports on a novel plasma-assisted approach to the synthesis of low-k thin films comprising pure-silica zeolite MFI. The proposed method involves treating the aged solution using an atmospheric pressure plasma jet (APPJ). The high reactivity of the resulting nitrogen plasma helps to produce zeolite crystals with high crystallinity and uniform crystal size distribution. The APPJ treatment also remarkably reduces the time for hydrothermal reaction. The zeolite MFI suspensions synthesized with the APPJ treatment are used for the wet deposition to form thin films. The deposited zeolite thin films possessed dense morphology and high crystallinity, which overcome the trade-off between crystallinity and film quality. Zeolite thin films synthesized using the proposed APPJ treatment achieve low leakage current (on the order of 10 -8 A/cm 2 ) and high Young's modulus (12 GPa), outperforming the control sample synthesized without plasma treatment. The dielectric constant of our zeolite thin films was as low as 1.41. The overall performance of the low-k thin films synthesized with the APPJ treatment far exceed existing low-k films comprising pure-silica MFI.

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.

The development of beryllium plasma spray technology for the International Thermonuclear Experimental Reactor (ITER)

International Nuclear Information System (INIS)

Castro, R.G.; Elliott, K.E.; Hollis, K.J.; Watson, R.D.

1999-01-01

Over the past five years, four international parties, which include the European Communities, Japan, the Russian Federation and the United States, have been collaborating on the design and development of the International Thermonuclear Experimental Reactor (ITER), the next generation magnetic fusion energy device. During the ITER Engineering Design Activity (EDA), beryllium plasma spray technology was investigated by Los Alamos National Laboratory as a method for fabricating and repairing and the beryllium first wall surface of the ITER tokamak. Significant progress has been made in developing beryllium plasma spraying technology for this application. Information will be presented on the research performed to improve the thermal properties of plasma sprayed beryllium coatings and a method that was developed for cleaning and preparing the surface of beryllium prior to depositing plasma sprayed beryllium coatings. Results of high heat flux testing of the beryllium coatings using electron beam simulated ITER conditions will also be presented

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.

Low pressure plasma discharges for the sterilization and decontamination of surfaces

International Nuclear Information System (INIS)

Rossi, F; Rauscher, H; Hasiwa, M; Gilliland, D; Kylian, O

2009-01-01

The mechanisms of sterilization and decontamination of surfaces are compared in direct and post discharge plasma treatments in two low-pressure reactors, microwave and inductively coupled plasma. It is shown that the removal of various biomolecules, such as proteins, pyrogens or peptides, can be obtained at high rates and low temperatures in the inductively coupled plasma (ICP) by using Ar/O 2 mixtures. Similar efficiency is obtained for bacterial spores. Analysis of the discharge conditions illustrates the role of ion bombardment associated with O radicals, leading to a fast etching of organic matter. By contrast, the conditions obtained in the post discharge lead to much lower etching rates but also to a chemical modification of pyrogens, leading to their de-activation. The advantages of the two processes are discussed for the application to the practical case of decontamination of medical devices and reduction of hospital infections, illustrating the advantages and drawbacks of the two approaches.

Low pressure plasma discharges for the sterilization and decontamination of surfaces

Energy Technology Data Exchange (ETDEWEB)

Rossi, F; Rauscher, H; Hasiwa, M; Gilliland, D [European Commission, Joint Research Centre, Institute for Health and Consumer Protection, Via E. Fermi 2749, 21027 Ispra (Vatican City State, Holy See) (Italy); Kylian, O [Faculty of Mathematics and Physics, Charles University, V Holesovickach 2, Prague 8, 180 00 (Czech Republic)], E-mail: francois.rossi@jrc.ec.europa.eu

2009-11-15

The mechanisms of sterilization and decontamination of surfaces are compared in direct and post discharge plasma treatments in two low-pressure reactors, microwave and inductively coupled plasma. It is shown that the removal of various biomolecules, such as proteins, pyrogens or peptides, can be obtained at high rates and low temperatures in the inductively coupled plasma (ICP) by using Ar/O{sub 2} mixtures. Similar efficiency is obtained for bacterial spores. Analysis of the discharge conditions illustrates the role of ion bombardment associated with O radicals, leading to a fast etching of organic matter. By contrast, the conditions obtained in the post discharge lead to much lower etching rates but also to a chemical modification of pyrogens, leading to their de-activation. The advantages of the two processes are discussed for the application to the practical case of decontamination of medical devices and reduction of hospital infections, illustrating the advantages and drawbacks of the two approaches.

Plasma spraying of refractory metals and refractory hard materials. State of the art

International Nuclear Information System (INIS)

Eschnauer, H.; Lugscheider, E.; Jaeger, D.

1989-01-01

Suitable spraying processes for manufacturing refractory metals, refractory hard materials as well as spray materials with refractory components are the VPS- and IPS-spraying techniques. The advantages of these special spraying process variations are described. The reactive spraying materials are systematically organized. The characteristical properties used in purpose of improving the substrate surfaces are explained. Finally some examples of the latest results of research concerning plasma spraying of reactive materials are shown. 16 refs., 10 figs. (Author)

Plasma sprayed alumina coatings for radiation detector development

Indian Academy of Sciences (India)

A mechanical as well as metallurgical bonding is necessary. 3. Applications ... Here the feasibility of using metallic components that were plasma spray- ... To study the electrical insulation, integrity of ceramic coating etc, tests were carried out.

Transient effects caused by pulsed gas and liquid injections into low pressure plasmas

International Nuclear Information System (INIS)

Ogawa, D; Goeckner, M; Overzet, L; Chung, C W

2010-01-01

The fast injection of liquid droplets into a glow discharge causes significant time variations in the pressure, the chemical composition of the gas and the phases present (liquid and/or solid along with gas). While the variations can be large and important, very few studies, especially kinetic studies, have been published. In this paper we examine the changes brought about in argon plasma by injecting Ar (gas), N 2 (gas) hexane (gas) and hexane (liquid droplets). The changes in the RF capacitively coupled power (forward and reflected), electron and ion density (n e , n i ), electron temperature (T e ) and optical emissions were monitored during the injections. It was found that the Ar injection (pressure change only) caused expected variations. The electron temperature reduced, the plasma density increased and the optical emission intensity remained nearly constant. The N 2 and hexane gas injections (chemical composition and pressure changes) also followed expected trends. The plasma densities increased and electron temperature decreased while the optical emissions changed from argon to the injected gas. These all serve to highlight the fact that the injection of evaporating hexane droplets in the plasma caused very little change. This is because the number of injected droplets is too small to noticeably affect the plasma, even though the shift in the chemical composition of the gas caused by evaporation from those same droplets can be very significant. The net conclusion is that using liquid droplets to inject precursors for low pressure plasmas is both feasible and controllable.

Wiedemann-Franz ratio in high-pressure and low-temperature thermal xenon plasma with 10% caesium

International Nuclear Information System (INIS)

Novakovic, N.V.; Milic, B.S.; Stojilkovic, S.M.

1995-01-01

Theoretical investigations of various transport properties of low-temperature noble-gas plasmas with additives has aroused a continuous interest over a considerable spall of time, due to numerous applications. In this paper the results of a theoretical evaluation of electrical conductivity, thermal conductivity and their ratio (the Wiedemann-Franz ratio) in xenon plasma with 10% of argon and 10% of caesium are presented, for the temperature range from 2000 K to 20000 K, and for pressures equal to or 5, 10, and 15 time higher than the normal atmospheric pressure. The plasma was regarded as weakly non-ideal and in the state of local thermodynamical equilibrium with the assumption that the equilibrium is attained with the pressure kept constant. The plasma composition was determined on the ground of a set of Saha equations; the ionization energy lowerings were expressed with the aid of a modified plasma Debye radius r* D (rather than the standard r D ), as proposed previously

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

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

Science.gov (United States)

Ctibor, P.; Nevrla, B.; Cizek, J.; Lukac, F.

2017-12-01

A novel thermal barrier coating (TBC) material, strontium zirconate SrZrO3, was sprayed by a high feed-rate water-stabilized plasma torch WSP 500. Stainless steel coupons were used as substrates. Coatings with a thickness of about 1.2 mm were produced, whereas the substrates were preheated over 450 °C. The torch worked at 150 kW power and was able to spray SrZrO3 with a high spray rate over 10 kg per hour. Microstructure and microhardness, phase composition, adhesion, thermal conductivity and thermal expansion were evaluated. The coating has low thermal conductivity under 1 W/m K in the interval from room temperature up to 1200 °C. Its crystallite size is slightly over 400 nm and thermal expansion 12.3 µm K-1 in the similar temperature range.

Controlling of Nitriding Process on Reactive Plasma Spraying of Al Particles

Energy Technology Data Exchange (ETDEWEB)

Shahien, Mohammed [Graduate Student, Toyohashi University of Technology (Japan); Yamada, Motohiro; Yasui, Toshiaki; Fukumoto, Masahiro, E-mail: mo.shahien@yahoo.com [Toyohashi University of Technology (Japan)

2011-10-29

Reactive plasma spraying (RPS) has been considered as a promising technology for in-situ formation of aluminum nitride (AlN) thermally sprayed coatings. To fabricate thick A lN coatings in RPS process, controlling and improving the in-flight nitriding reaction of Al particles is required. In this study, it was possible to control the nitriding reaction by using ammonium chloride (NH{sub 4}Cl) powders. Thick and dense AlN coating (more than 300 {mu}m thickness) was successfully fabricated with small addition of NH{sub 4}Cl powders. Thus, addition of NH{sub 4}Cl prevented the Al aggregation by changing the reaction pathway to a mild way with no explosive mode (relatively low heating rates) and it acts as a catalyst, nitrogen source and diluent agent.

Argon Shrouded Plasma Spraying of Tantalum over Titanium for Corrosion Protection in Fluorinated Nitric Acid Media

Science.gov (United States)

Vetrivendan, E.; Jayaraj, J.; Ningshen, S.; Mallika, C.; Kamachi Mudali, U.

2018-02-01

Argon shrouded plasma spraying (ASPS) was used to deposit a Ta coating on commercially pure Ti (CP-Ti) under inert argon, for dissolver vessel application in the aqueous spent fuels reprocessing plant with high plutonium content. Oxidation during plasma spraying was minimized by shrouding argon system. Porosity and oxide content were controlled by optimizing the spraying parameters, to obtain a uniform and dense Ta coating. The Ta particle temperature and velocity were optimized by judiciously controlling the spray parameters, using a spray diagnostic charge-coupled device camera. The corrosion resistance of the Ta coatings developed by ASPS was investigated by electrochemical studies in 11.5 M HNO3 and 11.5 M HNO3 + 0.05 M NaF. Similarly, the durability of the ASPS Ta coating/substrate was evaluated as per ASTM A262 Practice-C test in boiling nitric acid and fluorinated nitric acid for 240 h. The ASPS Ta coating exhibited higher corrosion resistance than the CP-Ti substrate, as evident from electrochemical studies, and low corrosion rate with excellent coating stability in boiling nitric, and fluorinated nitric acid. The results of the present study revealed that tantalum coating by ASPS is a promising strategy for improving the corrosion resistance in the highly corrosive reprocessing environment.

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.

Laser treatment of plasma sprayed HA coatings

NARCIS (Netherlands)

Khor, KA; Vreeling, A; Dong, ZL; Cheang, P

1999-01-01

Laser treatment was conducted on plasma sprayed hydroxyapatite (HA) coatings using a Nd-YAG pulse laser. Various laser parameters were investigated. The results showed that the HA surface melted when an energy level of greater than or equal to 2 J and a spot size of 2 mm was employed during

The influence of pore formers on the microstructure of plasma-sprayed NiO-YSZ anodes

Science.gov (United States)

Poon, Michael; Kesler, Olivera

2012-07-01

Four types of pore formers: high-density polyethylene (HDPE), polyether-ether-ketone (PEEK), mesocarbon-microbead (MCMB) carbon powder, and baking flour, are processed and characterized, then incorporated with NiO-YSZ nano-agglomerate powder to produce plasma sprayed SOFC anode coatings. Scanning electron microscopy (SEM) of the coating microstructure, gas permeability measurements, and porosity determinations by image analysis are used to evaluate the effectiveness of each potential pore former powder. Under the spray conditions studied, the flour and MCMB pore former powders are effective as plasma sprayed pore formers, increasing the permeability of the coatings by factors of four and two, respectively, compared to a similarly sprayed NiO-YSZ coating without pore formers. The HDPE powder is unable to survive the plasma spray process and does not contribute to the final coating porosity. The PEEK pore former, though ineffective with the current powder characteristics and spray parameters, exhibits the highest relative deposition efficiency and the most favorable thermal characteristics.

Low-pressure plasma enhanced immobilization of chitosan on low-density polyethylene for bio-medical applications

International Nuclear Information System (INIS)

Pandiyaraj, K. Navaneetha; Ferraria, Ana Maria; Rego, Ana Maria Botelho do; Deshmukh, Rajendra R.; Su, Pi-Guey; Halleluyah, Jr. Mercy; Halim, Ahmad Sukari

2015-01-01

Highlights: • Acrylic acid (AAc) was grafted on LDPE film by in situ plasma polymerization. • Molecules of PEG and chitosan were immobilized on AAc grafted LDPE films. • Surface modified LDPE exhibits excellent hydrophilic property. • Surface modified LDPE resist the adsorption of protein and adhesion of platelets. - Abstract: With the aim of improving blood compatibility of low density polyethylene (LDPE) films, an effective low-pressure plasma technology was employed to functionalize the LDPE film surfaces through in-situ grafting of acrylic acid (AAc). Subsequently, the molecules of poly(ethylene glycol) (PEG) and chitosan (CHI) were immobilized on the surface of grafted LDPE films. The unmodified and modified LDPE films were analyzed using various characterization techniques such as contact angle, atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) and X-ray photo electron spectroscopy (XPS) to understand the changes in surface properties such as hydrophilicity, surface topography and chemical composition, respectively. Furthermore, LDPE films have been subjected to an ageing process to determine the durability of the plasma assisted surface modification. The blood compatibility of the surface modified LDPE films was confirmed by in vitro tests. It was found that surface modified LDPE films show better hydrophilic behavior compared with the unmodified one. FTIR and XPS results confirm the successful immobilization of CHI on the surface of LDPE films. LDPE films showed marked morphological changes after grafting of AAc, PEG and CHI which were confirmed through AFM imaging. The in vitro blood compatibility tests have clearly demonstrated that CHI immobilized LDPE films exhibit remarkable anti thrombogenic nature compared with other modified films. Surface modified LDPE films through low-pressure plasma technique could be adequate for biomedical implants such as artificial skin substrates, urethral catheters or cardiac stents

Low-pressure plasma enhanced immobilization of chitosan on low-density polyethylene for bio-medical applications

Energy Technology Data Exchange (ETDEWEB)

Pandiyaraj, K. Navaneetha, E-mail: dr.knpr@gmail.com [Surface Engineering Laboratory, Department of Physics, Sri Shakthi Institute of Engineering and Technology, L& T by pass, Chinniyam Palayam (post), Coimbatore, 641062 (India); Ferraria, Ana Maria; Rego, Ana Maria Botelho do [Centro de Química- Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon (Portugal); Deshmukh, Rajendra R. [Department of Physics, Institute of Chemical Technology, Matunga, Mumbai 400 019 (India); Su, Pi-Guey [Department of Chemistry, Chinese Culture University, Taipei 111, Taiwan (China); Halleluyah, Jr. Mercy; Halim, Ahmad Sukari [Reconstructive Science Unit, School of Medical Sciences, Health Campus, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia)

2015-02-15

Highlights: • Acrylic acid (AAc) was grafted on LDPE film by in situ plasma polymerization. • Molecules of PEG and chitosan were immobilized on AAc grafted LDPE films. • Surface modified LDPE exhibits excellent hydrophilic property. • Surface modified LDPE resist the adsorption of protein and adhesion of platelets. - Abstract: With the aim of improving blood compatibility of low density polyethylene (LDPE) films, an effective low-pressure plasma technology was employed to functionalize the LDPE film surfaces through in-situ grafting of acrylic acid (AAc). Subsequently, the molecules of poly(ethylene glycol) (PEG) and chitosan (CHI) were immobilized on the surface of grafted LDPE films. The unmodified and modified LDPE films were analyzed using various characterization techniques such as contact angle, atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) and X-ray photo electron spectroscopy (XPS) to understand the changes in surface properties such as hydrophilicity, surface topography and chemical composition, respectively. Furthermore, LDPE films have been subjected to an ageing process to determine the durability of the plasma assisted surface modification. The blood compatibility of the surface modified LDPE films was confirmed by in vitro tests. It was found that surface modified LDPE films show better hydrophilic behavior compared with the unmodified one. FTIR and XPS results confirm the successful immobilization of CHI on the surface of LDPE films. LDPE films showed marked morphological changes after grafting of AAc, PEG and CHI which were confirmed through AFM imaging. The in vitro blood compatibility tests have clearly demonstrated that CHI immobilized LDPE films exhibit remarkable anti thrombogenic nature compared with other modified films. Surface modified LDPE films through low-pressure plasma technique could be adequate for biomedical implants such as artificial skin substrates, urethral catheters or cardiac stents

A study on the effect of heat treatment on electrical properties of plasma sprayed YSZ

International Nuclear Information System (INIS)

Elshikh, S.S.M.

2012-01-01

Free standing samples of plasma sprayed (PS) zirconia partially stabilized with yettria (YSZ) were prepared with two machines of plasma spray deposition (Triplex gun- 100 kw, F-4 gun 64 kw) have different electrical power and spraying parameters, which produced different microstructures; contain different amounts and varieties of pores and micro-cracks.The study included heat treatment of samples at 1200 degree C for 1 h, 5 h, 10 h, 100 h and 500 h, to study the changes in macrostructure (pores and micro-cracks) which affect the electrical conductivity.The electrical properties (resistively, electrical conductivity) of plasma sprayed ZrO 2 stabilized by 8 wt. % Y 2 O 3 samples were determined by using electrical impedance spectroscopy (IS). Specimen's microstructure was examined by optical microscopy. By measuring electrical properties and connected porosity percent of the coatings obtained under various spraying conditions, it would be possible to select the optimum spraying condition to spray coatings which have high efficiency at high temperature.The results showed that the electrical conductivity of (YSZ) samples after heat treatment increased by a rate of (20%-30%) as compared to that of as sprayed.

Spray structure of a pressure-swirl atomizer for combustion applications

OpenAIRE

Jicha Miroslav; Jedelsky Jan; Durdina Lukas

2012-01-01

In the present work, global as well as spatially resolved parameters of a spray produced by a pressure-swirl atomizer are obtained. Small pressure-swirl atomizer for aircraft combustion chambers was run on a newly designed test bench with Jet A-1 kerosene type aviation fuel. The atomizer was tested in four regimes based on typical operation conditions of the engine. Spray characteristics were studied using two optical measurement systems, Particle Image velocimetry (PIV) and Phase-Doppler Par...

Sterilization of beehive material with a double inductively coupled low pressure plasma

International Nuclear Information System (INIS)

Priehn, M; Leichert, L I; Denis, B; Awakowicz, P; Aumeier, P; Kirchner, W H

2016-01-01

American Foulbrood is a severe, notifiable disease of the honey bee. It is caused by infection of bee larvae with spores of the gram-positive bacterium Paenibacillus larvae . Spores of this organism are found in high numbers in an infected hive and are highly resistant to physical and chemical inactivation methods. The procedures to rehabilitate affected apiaries often result in the destruction of beehive material. In this study we assess the suitability of a double inductively coupled low pressure plasma as a non-destructive, yet effective alternative inactivation method for bacterial spores of the model organism Bacillus subtilis on beehive material. Plasma treatment was able to effectively remove spores from wax, which, under protocols currently established in veterinary practice, normally is destroyed by ignition or autoclaved for sterilization. Spores were removed from wooden surfaces with efficacies significantly higher than methods currently used in veterinary practice, such as scorching by flame treatment. In addition, we were able to non-destructively remove spores from the highly delicate honeycomb wax structures, potentially making treatment of beehive material with double inductively coupled low pressure plasma part of a fast and reliable method to rehabilitate infected bee colonies with the potential to re-use honeycombs. (paper)

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.

RF power absorption by plasma of low pressure low power inductive discharge located in the external magnetic field

Science.gov (United States)

Kralkina, E. A.; Rukhadze, A. A.; Nekliudova, P. A.; Pavlov, V. B.; Petrov, A. K.; Vavilin, K. V.

2018-03-01

Present paper is aimed to reveal experimentally and theoretically the influence of magnetic field strength, antenna shape, pressure, operating frequency and geometrical size of plasma sources on the ability of plasma to absorb the RF power characterized by the equivalent plasma resistance for the case of low pressure RF inductive discharge located in the external magnetic field. The distinguishing feature of the present paper is the consideration of the antennas that generate not only current but charge on the external surface of plasma sources. It is shown that in the limited plasma source two linked waves can be excited. In case of antennas generating only azimuthal current the waves can be attributed as helicon and TG waves. In the case of an antenna with the longitudinal current there is a surface charge on the side surface of the plasma source, which gives rise to a significant increase of the longitudinal and radial components of the RF electric field as compared with the case of the azimuthal antenna current.

Heat removal tests for pressurized water reactor containment spray by largescale facility

International Nuclear Information System (INIS)

Motoki, Y.; Hashimoto, K.; Kitani, S.; Naritomi, M.; Nishio, G.; Tanaka, M.

1983-01-01

Heat removal tests for pressurized water reactor (PWR) containment spray were carried out to investigate effectiveness of the depressurization by Japan Atomic Energy Research Institute model containment (7-m diameter, 20 m high, and 708-m 3 volume) with PWR spray nozzles. The depressurization rate is influenced by the spray heat transfer efficiency and the containment wall surface heat transfer coefficient. The overall spray heat transfer efficiency was investigated with respect to spray flow rate, weight ratio of steam/air, and spray height. The spray droplet heat transfer efficiency was investigated whether the overlapping of spray patterns gives effect or not. The effect was not detectable in the range of large value of steam/air, however, it was better in the range of small value of it. The experimental results were compared with the calculated results by computer code CONTEMPT-LT/022. The overall spray heat transfer efficiency was almost 100% in the containment pressure, ranging from 2.5 to 0.9 kg/cm 2 X G, so that the code was useful on the prediction of the thermal hydraulic behavior of containment atmosphere in a PWR accident condition

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.

The nonlocal electron kinetics for a low-pressure glow discharge dusty plasma

Science.gov (United States)

Liang, Yonggan; Wang, Ying; Li, Hui; Tian, Ruihuan; Yuan, Chengxun; Kudryavtsev, A. A.; Rabadanov, K. M.; Wu, Jian; Zhou, Zhongxiang; Tian, Hao

2018-05-01

The nonlocal electron kinetic model based on the Boltzmann equation is developed in low-pressure argon glow discharge dusty plasmas. The additional electron-dust elastic and inelastic collision processes are considered when solving the kinetic equation numerically. The orbital motion limited theory and collision enhanced collection approximation are employed to calculate the dust surface potential. The electron energy distribution function (EEDF), effective electron temperature Teff, and dust surface potential are investigated under different plasma and dust conditions by solving the Boltzmann and the dust charging current balance equations self-consistently. A comparison of the calculation results obtained from nonlocal and local kinetic models is made. It is shown that the appearance of dust particles leads to a deviation of the EEDF from its original profile for both nonlocal and local kinetic models. With the increase in dust density and size, the effective electron temperature and dust surface potential decrease due to the high-energy electron loss on the dust surface. Meanwhile, the nonlocal and local results differ much from each other under the same calculation condition. It is concluded that, for low-pressure (PR ≤ 1 cm*Torr) glow discharge dusty plasmas, the existence of dust particles will amplify the difference of local and nonlocal EEDFs, which makes the local kinetic model more improper to determine the main parameters of the positive column. The nonlocal kinetic model should be used for the calculation of the EEDFs and dusty plasma parameters.

Investigation on the suitability of plasma sprayed Fe-Cr-Al coatings as tritium permeation barrier

International Nuclear Information System (INIS)

Fazio, C.; Serra, E.; Benamati, G.

1999-01-01

Results on the fabrication of a tritium permeation barrier by spraying Fe-Cr-Al powders are described. The sprayed coatings were deposited at temperatures below the A c1 temperature of the ferritic-martensitic steel substrate and no post-deposition heat treatment was applied. The aim of the investigation was the determination of the efficiency of the coatings to act as tritium permeation barrier. Metallurgical investigations as well as hydrogen isotope permeation measurements were carried out onto the produced coatings. The depositions were performed on ferritic-martensitic steels by means of three types of spray techniques: high velocity oxy fuel, air plasma spray and vacuum plasma spray. (orig.)

Transformation kinetics in plasma-sprayed barium- and strontium-doped aluminosilicate (BSAS)

International Nuclear Information System (INIS)

Harder, B.J.; Faber, K.T.

2010-01-01

The hexacelsian-to-celsian phase transformation in Ba 1-x Sr x Al 2 Si 2 O 8 is of interest for environmental barrier coating applications. Plasma-sprayed microstructures were heat treated above 1100 o C and the kinetics of the hexacelsian-to-celsian transformation were quantified. Activation energies for bulk and crushed materials were determined to be ∼340 and ∼500 kJ mol -1 , respectively. X-ray diffraction and electron backscattered diffraction were used to establish how plasma spraying barium- and strontium-doped aluminosilicate effectively reduces the energy required for its transformation.

Plasma sprayed coatings on mild steel split moulds for uranium casting

International Nuclear Information System (INIS)

Sreekumar, K.P.; Padmanaban, P.V.A.; Venkatramani, N.; Singh, S.P.; Saha, D.P.; Date, V.G.

2002-01-01

High velocity high temperature plasma jets are used to deposit metals and ceramics on metallic substrates for oxidation and corrosion protection applications. Plasma sprayed ceramic coatings on metallic substrates are also used to prevent its reaction with molten metals. Metal-alumina duplex coatings on mild steel split moulds have been developed and successfully used for casting of uranium. Techno-economics of the coated moulds against the conventional graphite moulds are a major advantage. Mild steel moulds of 600 mm long and 75 mm in diameter have been plasma spray coated with alumina over a bond coat of molybdenum. In-plant tests showed an increase in number of castings per mould compared to the commonly used graphite moulds. (author)

Influence of atmospheric pressure low-temperature plasma treatment on the shear bond strength between zirconia and resin cement.

Science.gov (United States)

Ito, Yuki; Okawa, Takahisa; Fukumoto, Takahiro; Tsurumi, Akiko; Tatsuta, Mitsuhiro; Fujii, Takamasa; Tanaka, Junko; Tanaka, Masahiro

2016-10-01

Zirconia exhibits excellent strength and high biocompatibility in technological applications and it is has therefore been investigated for clinical applications and research. Before setting prostheses, a crown prosthesis inner surface is sandblasted with alumina to remove contaminants and form small cavities. This alumina sandblasting causes stress-induced phase transition of zirconia. Atmospheric-pressure low-temperature plasma has been applied in the dental industry, particularly for adhesives, as a surface treatment to activate the surface energy and remove contaminants. The purpose of this study was to examine the influence of atmospheric-pressure low-temperature plasma treatment on the shear bond strength between zirconia and adhesive resin cement. The surface treatment method was classified into three groups: untreated (Cont group), alumina sandblast treatment (Sb group), and atmospheric-pressure low-temperature plasma treatment (Ps group). Adhesive resin cement was applied to stainless steel and bonded to zirconia. Shear adhesion tests were performed after complete hardening of the cement. Multiple comparisons were performed using a one-way analysis of variance and the Bonferroni method. X-ray diffractometry was used to examine the change in zirconia crystal structure. Statistically significant differences were noted between the control and Sb groups and between the control and Ps groups. In contrast, no statistically significant differences were noted for the Ps and Sb bond strength. Atmospheric-pressure low-temperature plasma treatment did not affect the zirconia crystal structure. Atmospheric-pressure low-temperature plasma treatment improves the bonding strength of adhesive resin cement as effectively as alumina sandblasting, and does not alter the zirconia crystal structure. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Microstructure and mechanical properties of plasma sprayed HA/YSZ/Ti-6Al-4V composite coatings.

Science.gov (United States)

Khor, K A; Gu, Y W; Pan, D; Cheang, P

2004-08-01

Plasma sprayed hydroxyapatite (HA) coatings on titanium alloy substrate have been used extensively due to their excellent biocompatibility and osteoconductivity. However, the erratic bond strength between HA and Ti alloy has raised concern over the long-term reliability of the implant. In this paper, HA/yttria stabilized zirconia (YSZ)/Ti-6Al-4V composite coatings that possess superior mechanical properties to conventional plasma sprayed HA coatings were developed. Ti-6Al-4V powders coated with fine YSZ and HA particles were prepared through a unique ceramic slurry mixing method. The so-formed composite powder was employed as feedstock for plasma spraying of the HA/YSZ/Ti-6Al-4V coatings. The influence of net plasma energy, plasma spray standoff distance, and post-spray heat treatment on microstructure, phase composition and mechanical properties were investigated. Results showed that coatings prepared with the optimum plasma sprayed condition showed a well-defined splat structure. HA/YSZ/Ti-6Al-4V solid solution was formed during plasma spraying which was beneficial for the improvement of mechanical properties. There was no evidence of Ti oxidation from the successful processing of YSZ and HA coated Ti-6Al-4V composite powders. Small amount of CaO apart from HA, ZrO(2) and Ti was present in the composite coatings. The microhardness, Young's modulus, fracture toughness, and bond strength increased significantly with the addition of YSZ. Post-spray heat treatment at 600 degrees C and 700 degrees C for up to 12h was found to further improve the mechanical properties of coatings. After the post-spray heat treatment, 17.6% increment in Young's modulus (E) and 16.3% increment in Vicker's hardness were achieved. The strengthening mechanisms of HA/YSZ/Ti-6Al-4V composite coatings were related to the dispersion strengthening by homogeneous distribution of YSZ particles in the matrix, the good mechanical properties of Ti-6Al-4V and the formation of solid solution among HA

Antibacterial characteristics of thermal plasma spray system.

Science.gov (United States)

Goudarzi, M; Saviz, Sh; Ghoranneviss, M; Salar Elahi, A

2018-03-15

The objective of this study is to investigate antibacterial characteristics of a thermal plasma spray system. For this purpose, copper powder was coated on a handmade atmospheric plasma spraying system made by the stainless steel 316 substrate, which is preheated at different temperatures before spraying. A number of deposition characteristics such as antibacterial characteristics, adhesion strength and hardness of coating, was investigated. All of the spray parameters are fixed except the substrate temperature. The chemical composition was analyzed by X-ray diffraction (XRD). A scanning electron microscopy (SEM) and back scattering electron microscopy (BSE) were used to show the coating microstructure, its thickness and also the powder micrograph. The energy dispersive X-ray spectroscopy (EDX) was used to analyze the coating particles. Hardness of the deposition was examined by Vickers tester (HV0.1). Its adhesion strength was declared by cross cut tester (TQC). In addition, the percentage of bactericidal coating was evidenced with Staphylococcus aurous and Escherichia coli bacteria. Study results show that as the substrates temperature increases, the number of splats in the shape of pancake increases, the greatness and percentage of the deposition porosity both decrease. The increment of the substrate temperature leads to more oxidation and makes thicker dendrites on the splat. The enhancement of the substrate temperature also enlarges thickness and efficiency of coating. The interesting results are that antibacterial properties of coatings against the Escherichia coli are more than Staphylococcus aurous bacteria. However the bactericidal percentage of the coatings against Staphylococcus aurous and Escherichia coli bacteria roughly does not change with increasing the substrate temperature. Furthermore, by increment of the substrate temperature, coatings with both high adhesion and hardness are obtained. Accordingly, the temperature of substrate can be an

Proceedings of the 16th symposium on plasma physics and technology

International Nuclear Information System (INIS)

1993-01-01

Among 53 papers collected in the proceedings, 28 papers deal with the theory and modelling (8 papers), experimental research (11 papers) and diagnostics of high-temperature plasmas. These include lower hybrid current drive in tokamaks, plasma heating by electron beams, laser plasma interaction and z-pinch experiments. In the diagnostic papers, attention is mostly paid to X-ray and optical plasma spectroscopy and to advanced Langmuir probe diagnostics. The remaining papers discuss low-temperature plasmas and their applications. In this group, 8 papers deal with low-pressure electric discharges, 5 papers with high-pressure arcs, glidarcs and plasma torches, and 12 papers with various plasma technology topics, such as thin film deposition, plasma spraying and plasma chemistry. (J.U.)

Improvement of technical purpose materials performance characteristics with the radio frequency low pressure plasma

Science.gov (United States)

Makhotkina, L. Yu; Khristoliubova, V. I.

2017-11-01

The main aim of the work is to solve the actual problem of increasing the competitiveness of tanning products by reducing the prime cost and improving the quality of finished products due to the increased durability of the working elements of tanneries. The impact of the low pressure radio frequency (RF) plasma in the processes of treating for modification of the materials for special purposes is considered in the article. The results of working elements of tanneries and the materials for special purposes sample processing by a RF low pressure plasma are described. As a result of leather materials nano structuring and nano modifying physical, mechanical and hygienic characteristics were increased. Processing of the technical purpose materials allows to increase operational performance of products and extend their lifespan.

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

Directory of Open Access Journals (Sweden)

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.

Mueller matrix polarimetry on plasma sprayed thermal barrier coatings for porosity measurement.

Science.gov (United States)

Luo, David A; Barraza, Enrique T; Kudenov, Michael W

2017-12-10

Yttria-stabilized zirconia (YSZ) is the most widely used material for thermal plasma sprayed thermal barrier coatings (TBCs) used to protect gas turbine engine parts in demanding operation environments. The superior material properties of YSZ coatings are related to their internal porosity level. By quantifying the porosity level, tighter control on the spraying process can be achieved to produce reliable coatings. Currently, destructive measurement methods are widely used to measure the porosity level. In this paper, we describe a novel nondestructive approach that is applicable to classify the porosity level of plasma sprayed YSZ TBCs via Mueller matrix polarimetry. A rotating retarder Mueller matrix polarimeter was used to measure the polarization properties of the plasma sprayed YSZ coatings with different porosity levels. From these measurements, it was determined that a sample's measured depolarization ratio is dependent on the sample's surface roughness and porosity level. To this end, we correlate the depolarization ratio with the samples' surface roughness, as measured by a contact profilometer, as well as the total porosity level, in percentage measured using a micrograph and stereological analysis. With the use of this technique, a full-field and rapid measurement of porosity level can be achieved.

An electron microscopy study of the effect of Ce on plasma sprayed bronze coatings

Science.gov (United States)

Wensheng, Li; Wang, S. C.; Ma, Chao; Zhiping, Wang

2012-07-01

The Cu-Al eutectoid alloy is an excellent material for mould due to its superior low friction. The conventional sand casting technique, however, is not feasible to fabricate high Al bronze because of high hardness and brittleness. Plasma arc spray has been used to produce high Al/Fe bronze coatings for mould. The inherent impurities such as H, O, N, S during the spray, however, may affect the coating's mechanical strength. One approach is to utilise the active rare earth Ce to clean up these impurities. The study is to investigate the effect of Ce on the microstructure, which has few reported in the literature.

Ceramic Materials Selection of Fuel Crucibles based on Plasma Spray Coating for SFR

Energy Technology Data Exchange (ETDEWEB)

Song, Hoon; Kim, Jonghwan; Kim, Hyungtae; Ko, Youngmo; Woo, Yoonmyung; Oh, Seokjin; Kim, Kihwan; Lee, Chanbock [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-07-01

The plasma-sprayed coating can provide the crucible with a denser, more friable coating layer, compared with the more friable coating layer formed by slurry-coating, which was used to prevent the interaction between melt and crucibles. Plasma-sprayed coatings are consolidated by mechanical interlocking of the molten particles impacting on the substrate and are dense by the heat applied by the plasma. The increased coating density is advantageous because it should not require frequent re coating and U-Zr melt penetration through the protective layer is more difficult in a dense coating than in a porous coating. In this study, we used Vacuum Plasma Spray method to investigate permanent coatings for re-usable crucibles for melting and casting of metallic fuel onto niobium substrates. Niobium was selected as a substrate because of its refractory nature and the coefficient of thermal expansion is similar to that of many of the candidate materials. After the HfC, ZrC, TiC, TaC, Y{sub 2}O{sub 3}, and 8% YSZ coatings were applied the resulting microstructure and chemical compositions was characterized to find the optimum process conditions for coating. Thermal plasma-sprayed coatings of refractory materials can be applied to develop a re-usable crucible coating for metallic fuel, such as the U-Zr alloy proposed for sodium cooled fast reactors.

Study of geometrical and operational parameters controlling the low frequency microjet atmospheric pressure plasma characteristics

International Nuclear Information System (INIS)

Kim, Dan Bee; Rhee, J. K.; Moon, S. Y.; Choe, W.

2006-01-01

Controllability of small size atmospheric pressure plasma generated at low frequency in a pin to dielectric plane electrode configuration was studied. It was shown that the plasma characteristics could be controlled by geometrical and operational parameters of the experiment. Under most circumstances, continuous glow discharges were observed, but both the corona and/or the dielectric barrier discharge characteristics were observed depending on the position of the pin electrode. The plasma size and the rotational temperature were also varied by the parameters. The rotational temperature was between 300 and 490 K, being low enough to treat thermally sensitive materials

The Role of Spraying Parameters and Inert Gas Shrouding in Hybrid Water-Argon Plasma Spraying of Tungsten and Copper for Nuclear Fusion Applications

Czech Academy of Sciences Publication Activity Database

Matějíček, Jiří; Kavka, Tetyana; Bertolissi, Gabriele; Ctibor, Pavel; Vilémová, Monika; Mušálek, Radek; Nevrlá, Barbara

2013-01-01

Roč. 22, č. 5 (2013), s. 744-755 ISSN 1059-9630 R&D Projects: GA MPO FR-TI2/702; GA TA ČR TA01010300 Institutional support: RVO:61389021 Keywords : plasma spraying * tungsten * copper * inert gas shrouding * water-argon plasma torch * gas shroud * hybrid plasma torch * influence of spray parameters * nuclear fusion * oxidation Subject RIV: JG - Metallurgy Impact factor: 1.491, year: 2013 http://link.springer.com/content/pdf/10.1007%2Fs11666-013-9895-x.pdf

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. 225-230 ISSN 2008-2134 Institutional support: RVO:61389021 Keywords : Plasma spraying * Electrical properties * Strontium Zirconate * Insulators Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass OBOR OECD: Ceramics www.pccc.icrc.ac.ir/Articles/18/1/18/1010/

Effect of confining wall potential on charged collimated dust beam in low-pressure plasma

International Nuclear Information System (INIS)

Kausik, S. S.; Kakati, B.; Saikia, B. K.

2013-01-01

The effect of confining wall potential on charged collimated dust beam in low-pressure plasma has been studied in a dusty plasma experimental setup by applying electrostatic field to each channel of a multicusp magnetic cage. Argon plasma is produced by hot cathode discharge method at a pressure of 5×10 −4 millibars and is confined by a full line cusped magnetic field confinement system. Silver dust grains are produced by gas-evaporation technique and move upward in the form of a collimated dust beam due to differential pressure maintained between the dust and plasma chambers. The charged grains in the beam after coming out from the plasma column enter into the diagnostic chamber and are deflected by a dc field applied across a pair of deflector plates at different confining potentials. Both from the amount of deflection and the floating potential, the number of charges collected by the dust grains is calculated. Furthermore, the collimated dust beam strikes the Faraday cup, which is placed above the deflector plates, and the current (∼pA) so produced is measured by an electrometer at different confining potentials. The experimental results demonstrate the significant effect of confining wall potential on charging of dust grains

Effect of confining wall potential on charged collimated dust beam in low-pressure plasma

Energy Technology Data Exchange (ETDEWEB)

Kausik, S. S.; Kakati, B.; Saikia, B. K. [Centre of Plasma Physics, Institute for Plasma Research, Sonapur 782 402 (India)

2013-05-15

The effect of confining wall potential on charged collimated dust beam in low-pressure plasma has been studied in a dusty plasma experimental setup by applying electrostatic field to each channel of a multicusp magnetic cage. Argon plasma is produced by hot cathode discharge method at a pressure of 5×10{sup −4} millibars and is confined by a full line cusped magnetic field confinement system. Silver dust grains are produced by gas-evaporation technique and move upward in the form of a collimated dust beam due to differential pressure maintained between the dust and plasma chambers. The charged grains in the beam after coming out from the plasma column enter into the diagnostic chamber and are deflected by a dc field applied across a pair of deflector plates at different confining potentials. Both from the amount of deflection and the floating potential, the number of charges collected by the dust grains is calculated. Furthermore, the collimated dust beam strikes the Faraday cup, which is placed above the deflector plates, and the current (∼pA) so produced is measured by an electrometer at different confining potentials. The experimental results demonstrate the significant effect of confining wall potential on charging of dust grains.

Effect of confining wall potential on charged collimated dust beam in low-pressure plasma

Science.gov (United States)

Kausik, S. S.; Kakati, B.; Saikia, B. K.

2013-05-01

The effect of confining wall potential on charged collimated dust beam in low-pressure plasma has been studied in a dusty plasma experimental setup by applying electrostatic field to each channel of a multicusp magnetic cage. Argon plasma is produced by hot cathode discharge method at a pressure of 5×10-4 millibars and is confined by a full line cusped magnetic field confinement system. Silver dust grains are produced by gas-evaporation technique and move upward in the form of a collimated dust beam due to differential pressure maintained between the dust and plasma chambers. The charged grains in the beam after coming out from the plasma column enter into the diagnostic chamber and are deflected by a dc field applied across a pair of deflector plates at different confining potentials. Both from the amount of deflection and the floating potential, the number of charges collected by the dust grains is calculated. Furthermore, the collimated dust beam strikes the Faraday cup, which is placed above the deflector plates, and the current (˜pA) so produced is measured by an electrometer at different confining potentials. The experimental results demonstrate the significant effect of confining wall potential on charging of dust grains.

Treatment of Candida albicans biofilms with low-temperature plasma induced by dielectric barrier discharge and atmospheric pressure plasma jet

International Nuclear Information System (INIS)

Koban, Ina; Welk, Alexander; Meisel, Peter; Holtfreter, Birte; Kocher, Thomas; Matthes, Rutger; Huebner, Nils-Olaf; Kramer, Axel; Sietmann, Rabea; Kindel, Eckhard; Weltmann, Klaus-Dieter

2010-01-01

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 log 10 reduction factor of 1.5, the log 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.

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.

Plasma spraying of zirconium carbide – hafnium carbide – tungsten cermets

Czech Academy of Sciences Publication Activity Database

Brožek, Vlastimil; Ctibor, Pavel; Cheong, D.-I.; Yang, S.-H.

2009-01-01

Roč. 9, č. 1 (2009), s. 49-64 ISSN 1335-8987 Institutional research plan: CEZ:AV0Z20430508 Keywords : Plasma spraying * cermet coatings * microhardness * zirconium carbide * hafnium carbide * tungsten * water stabilized plasma Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

Thermal plasma spraying for SOFCs: Applications, potential advantages, and challenges

Energy Technology Data Exchange (ETDEWEB)

Hui, Rob; Wang, Zhenwei; Jankovic, Jasna; Yick, Sing; Maric, Radenka; Ghosh, Dave [National Research Council Institute for Fuel Cell Innovation, 4250 Wesbrook Mall, Vancouver, BC V6T 1W5 (Canada); Kesler, Olivera [National Research Council Institute for Fuel Cell Innovation, 4250 Wesbrook Mall, Vancouver, BC V6T 1W5 (Canada); Department of Mechanical Engineering, University of British Columbia, 2054-6250 Applied Science Lane, Vancouver, BC V6T 1Z4 (Canada); Rose, Lars [National Research Council Institute for Fuel Cell Innovation, 4250 Wesbrook Mall, Vancouver, BC V6T 1W5 (Canada); Department of Materials Engineering, University of British Columbia, 309-6350 Stores Road, Vancouver, BC V6T 1Z4 (Canada)

2007-07-10

In this article, the applications, potential advantages, and challenges of thermal plasma spray (PS) processing for nanopowder production and cell fabrication of solid oxide fuel cells (SOFCs) are reviewed. PS processing creates sufficiently high temperatures to melt all materials fed into the plasma. The heated material can either be quenched into oxide powders or deposited as coatings. This technique has been applied to directly deposit functional layers as well as nanopowder for SOFCs application. In particularly, low melting point and highly active electrodes can be directly fabricated on zirconia-based electrolytes. This is a simple processing technique that does not require the use of organic solvents, offering the opportunity for flexible adjustment of process parameters, and significant time saving in production of the cell and cost reduction compared with tape casting, screen printing and sintering processing steps. Most importantly, PS processing shows strong potential to enable the deposition of metal-supported SOFCs through the integrated fabrication of membrane-electrode assemblies (MEA) on porous metallic substrates with consecutive deposition steps. On the other hand, the application of PS processing to produce SOFCs faces some challenges, such as insufficient porosity of the electrodes, the difficulty of obtaining a thin (<10 {mu}m) and dense electrolyte layer. Fed with H{sub 2} as the fuel gas and oxygen as the oxidant gas, the plasma sprayed cell reached high power densities of 770 mW cm{sup -2} at 900 C and 430 mW cm{sup -2} at 800 C at a cell voltage of 0.7 V. (author)

Induction plasma-sprayed photocatalytically active titania coatings and their characterisation by micro-Raman spectroscopy

Czech Academy of Sciences Publication Activity Database

Burlacov, I.; Jirkovský, Jaromír; Muller, M.; Heimann, R. B.

2006-01-01

Roč. 201, 1-2 (2006), s. 255-264 ISSN 0257-8972 Grant - others:European Communities(XE) EVKI-2002-30025 Institutional research plan: CEZ:AV0Z40400503 Source of funding: R - rámcový projekt EK Keywords : titania (anatase) coatings * induction plasma spraying * suspension plasma spraying * Raman spectroscopy Subject RIV: CG - Electrochemistry Impact factor: 1.559, year: 2006

Diagnostics of plasma-biological surface interactions in low pressure and atmospheric pressure plasmas

International Nuclear Information System (INIS)

Ishikawa, Kenji; Hori, Masaru

2014-01-01

Mechanisms of plasma-surface interaction are required to understand in order to control the reactions precisely. Recent progress in atmospheric pressure plasma provides to apply as a tool of sterilization of contaminated foodstuffs. To use the plasma with safety and optimization, the real time in situ detection of free radicals - in particular dangling bonds by using the electron-spin-resonance (ESR) technique has been developed because the free radical plays important roles for dominantly biological reactions. First, the kinetic analysis of free radicals on biological specimens such as fungal spores of Penicillium digitatum interacted with atomic oxygen generated plasma electric discharge. We have obtained information that the in situ real time ESR signal from the spores was observed and assignable to semiquinone radical with a g-value of around 2.004 and a line width of approximately 5G. The decay of the signal was correlated with a link to the inactivation of the fungal spore. Second, we have studied to detect chemical modification of edible meat after the irradiation. Using matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF-MS) and ESR, signals give qualification results for chemical changes on edible liver meat. The in situ real-time measurements have proven to be a useful method to elucidate plasma-induced surface reactions on biological specimens. (author)

On reactive suspension plasma spraying of calcium titanate

OpenAIRE

Kotlan, J. (Jiří); Pala, Z. (Zdeněk); Mušálek, R. (Radek); Ctibor, P. (Pavel)

2016-01-01

This study shows possibility of preparation of calcium titanate powder and coatings by reactive suspension plasma spraying. Suspension of mixture of calcium carbonate (CaCO3) and titanium dioxide (TiO2) powders in ethanol was fed into hybrid plasma torch with a DC-arc stabilized by a water–argon mixture (WSP-H 500). Various feeding distances and angles were used in order to optimize suspension feeding conditions. In the next step, the coatings were deposited on stainless steel substrates and ...

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.

Process development for synthesis and plasma spray deposition of LaPO4 and YPO4 for nuclear applications

International Nuclear Information System (INIS)

Chakravarthy, Y.; Sreekumar, K.P.; Jayakumar, S.; Thiyagarajan, T.K.; Ananthapadmanabhan, P.V.; Das, A.K.; Gantayet, L.M.; Krishnan, K.

2009-01-01

Rare earth phosphates are geologically very stable and considered as potential matrix material for nuclear waste disposal and also for many high temperature thermal barrier and corrosion barrier applications involving molten metals. This paper focuses on developmental studies related to synthesis, thermal stability and plasma spray deposition of LaPO 4 and YPO 4 . The rare earth phosphates were synthesized by chemical method from their respective oxide materials using ortho phosphoric acid. The as-precipitated powders were converted to thermal spray grade powder by compaction, sintering and crushing. Thermal stability of these phosphates up to their melting point was determined by arc plasma melting, followed by X-ray diffraction. Results indicate that LaPO 4 and YPO 4 melt congruently without decomposition. Plasma spray deposition was carried out using the in-house 40 kW atmospheric plasma spray system. Adherent coatings could be deposited on various substrates by optimizing the plasma spray parameters. (author)

Effect of low-pressure plasma treatment on the color and oxidative stability of raw pork during refrigerated storage.

Science.gov (United States)

Ulbin-Figlewicz, Natalia; Jarmoluk, Andrzej

2016-06-01

The effect of low-pressure plasma on quality attributes of meat is an important aspect, which must be considered before application in food. The aim of this study was to determine the color, fatty acid composition, lipid oxidation expressed as thiobarbituric acid reactive substances and total antioxidant capacity of raw pork samples exposed to helium low-pressure plasma treatment (20 kPa) for 0, 2, 5, and 10 min during the storage period. The thiobarbituric acid reactive substance concentrations of all plasma-treated samples during storage were in the range from 0.26 to 0.61 mg malondialdehyde/kg. Exposure time caused significant changes only in total color difference, hue angle, and chroma after 10 min of treatment. Ferric reducing ability of plasma values of meat samples decreased from 1.93 to 1.40 mmol Trolox Eq/kg after 14 days of storage. The storage period significantly affected proportion of polyunsaturated fatty acids, with an increase about 3% after 14 days of refrigeration storage while the content of saturated fatty acids was at the same level. Helium low-pressure plasma does not induce oxidative processes. Application of this decontamination technique while maintaining product quality is possible in food industry. © The Author(s) 2015.

Deposition of porous cathodes using plasma spray technique for reduced-temperature SOFCs

Energy Technology Data Exchange (ETDEWEB)

Jankovic, J.; Hui, S.; Roller, J.; Kesler, O.; Xie, Y.; Maric, R.; Ghosh, D. [National Research Council of Canada, Vancouver, BC (Canada). Inst. for Fuel Cell Innovation

2005-07-01

Current techniques for Solid Oxide Fuel Cell (SOFC) materials deposition are often expensive and time-consuming. Plasma-spraying techniques provide higher deposition rates, short processing times and control over porosity and composition during deposition. Optimum plasma spraying for lanthanum based cathode materials were discussed. Plasma-spraying was used to deposit cathode materials onto ceramic and stainless steel substrates to obtain highly porous structures. Lanthanum cathode materials with composition of La{sub 0.6}Sr{sub 0.4}C{sub 0.2}Fe{sub 0.8}O{sub 3} were employed in the powder form. The powder was prepared from powder precursors with different power formers and binder levels, or from produced single-phase lanthanum powders. The (La{sub 0.8}Sr{sub 0.2}){sub 0.98}MnO{sub 3} cathode material was also processed for comparison purposes. The deposition process was developed to obtain coatings with good bond strength, porosity, film thickness and residual stresses. The phase and microstructure of deposited materials were characterized using X-Ray Diffraction and Scanning Electron Microscopy (SEM). It was concluded that good flow of the powder precursors is achieved by spraying 50-100 um particle size powders and using vibrating feeders. Further processing of the spraying powders was recommended. It was noted that oxide precursors showed greater reactivity among the precursors. The best precursor reactivity and coating morphology was obtained using 40 volume per cent of graphite pore former, incorporated into the precursor mixture during wet ball milling. It was concluded that higher power levels and larger distances between the plasma gun and the substrate result in coatings with the highest porosities and best phase compositions. 5 refs., 1 tab., 6 figs.

The Healing Effect of Low-Temperature Atmospheric-Pressure Plasma in Pressure Ulcer: A Randomized Controlled Trial.

Science.gov (United States)

Chuangsuwanich, Apirag; Assadamongkol, Tananchai; Boonyawan, Dheerawan

2016-12-01

Pressure ulcers are difficult to treat. Recent reports of low-temperature atmospheric-pressure plasma (LTAPP) indicated its safe and effectiveness in chronic wound care management. It has been shown both in vitro and vivo studies that LTAPP not only helps facilitate wound healing but also has antimicrobial efficacy due to its composition of ion and electron, free radicals, and ultraviolet ray. We studied the beneficial effect of LTAPP specifically on pressure ulcers. In a prospective randomized study, 50 patients with pressure ulcers were divided into 2 groups: Control group received standard wound care and the study group was treated with LTAPP once every week for 8 consecutive weeks in addition to standard wound care. We found that the group treated with LTAPP had significantly better PUSH (Pressure Ulcer Scale for Healing) scores and exudate amount after 1 week of treatment. There was also a reduction in bacterial load after 1 treatment regardless of the species of bacteria identified.

Influence of emitter temperature on the energy deposition in a low-pressure plasma

International Nuclear Information System (INIS)

Levko, Dmitry; Raja, Laxminarayan L.

2016-01-01

The influence of emitter temperature on the energy deposition into low-pressure plasma is studied by the self-consistent one-dimensional Particle-in-Cell Monte Carlo Collisions model. Depending on the emitter temperature, different modes of discharge operation are obtained. The mode type depends on the plasma frequency and does not depend on the ratio between the densities of beam and plasma electrons. Namely, plasma is stable when the plasma frequency is small. For this plasma, the energy transfer from emitted electrons to plasma electrons is inefficient. The increase in the plasma frequency results first in the excitation of two-stream electron instability. However, since the thermal velocity of plasma electrons is smaller than the electrostatic wave velocity, the resonant wave-particle interaction is inefficient for the energy deposition into the plasma. Further increase in the plasma frequency leads to the distortion of beam of emitted electrons. Then, the electrostatic wave generated due to two-stream instability decays into multiple slower waves. Phase velocities of these waves are comparable with the thermal velocity of plasma electrons which makes possible the resonant wave-particle interaction. This results in the efficient energy deposition from emitted electrons into the plasma.

The physics of the low-temperature plasma in Czechoslovakia

International Nuclear Information System (INIS)

Kracik, J.

1985-01-01

A survey is given of low-temperature plasma research in Czechoslovakia since 1954 and its main results are pointed out. In the first years, various processes in electric discharges and electromagnetic acceleration of plasma clusters were studied at Czechoslovak universities and in the Institute of Physics. In the study of ionization waves, Czechoslovak physicists achieved world priority. Later on, low-temperature plasma investigation began in the Institute of Plasma Physics, founded in 1959. The issues of plasma interaction with the solid state and plasma applications in plasma chemistry were studied mainly by its Department of Applied Plasma Physics. The main effort of this group, transferred recently to the Institute of Physics, is aimed at thin film production and plasma-surface interactions; similar experimental studies are also carried out at universities in Brno and Bratislava. Last but not least, arc spraying of powder materials using water-cooled plasmatrons is being developed by the Department of Plasma Technology of the Institute of Plasma Physics. (J.U.)

Plasma sprayed metal supported YSZ/Ni-LSGM-LSCF ITSOFC with nanostructured anode

Science.gov (United States)

Hwang, Changsing; Tsai, Chun-Huang; Lo, Chih-Hung; Sun, Cha-Hong

Intermediate temperature solid oxide fuel cells (ITSOFCs) supported by a porous Ni-substrate and based on Sr and Mg doped lanthanum gallate (LSGM) electrolyte, lanthanum strontium cobalt ferrite (LSCF) cathode and nanostructured yttria stabilized zirconia-nickel (YSZ/Ni) cermet anode have been fabricated successfully by atmospheric plasma spraying (APS). From ac impedance analysis, the sprayed YSZ/Ni cermet anode with a novel nanostructure and advantageous triple phase boundaries after hydrogen reduction has a low resistance. It shows a good electrocatalytic activity for hydrogen oxidation reactions. The sprayed LSGM electrolyte with ∼60 μm in thickness and ∼0.054 S cm -1 conductivity at 800 °C shows a good gas tightness and gives an open circuit voltage (OCV) larger than 1 V. The sprayed LSCF cathode with ∼30 μm in thickness and ∼30% porosity has a minimum resistance after being heated at 1000 °C for 2 h. This cathode keeps right phase structure and good porous network microstructure for conducting electrons and negative oxygen ions. The APS sprayed cell after being heated at 1000 °C for 2 h has a minimum inherent resistance and achieves output power densities of ∼440 mW cm -2 at 800 °C, ∼275 mW cm -2 at 750 °C and ∼170 mW cm -2 at 700 °C. Results from SEM, XRD, ac impedance analysis and I- V- P measurements are presented here.

Large area atmospheric-pressure plasma jet

Science.gov (United States)

Selwyn, Gary S.; Henins, Ivars; Babayan, Steve E.; Hicks, Robert F.

2001-01-01

Large area atmospheric-pressure plasma jet. A plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two planar, parallel electrodes are employed to generate a plasma in the volume therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly spacing the rf-powered electrode. Because of the atmospheric pressure operation, there is a negligible density of ions surviving for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike the situation for low-pressure plasma sources and conventional plasma processing methods.

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

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.

Deposition of Composite LSCF-SDC and SSC-SDC Cathodes by Axial-Injection Plasma Spraying

Science.gov (United States)

Harris, Jeffrey; Qureshi, Musab; Kesler, Olivera

2012-06-01

The performance of solid oxide fuel cell cathodes can be improved by increasing the number of electrochemical reaction sites, by controlling microstructures, or by using composite materials that consist of an ionic conductor and a mixed ionic and electronic conductor. LSCF (La0.6Sr0.4Co0.2Fe0.8O3-δ) and SSC (Sm0.5Sr0.5CoO3) cathodes were manufactured by axial-injection atmospheric plasma spraying, and composite cathodes were fabricated by mixing SDC (Ce0.8Sm0.2O1.9) into the feedstock powders. The plasma power was varied by changing the proportion of nitrogen in the plasma gas. The microstructures of cathodes produced with different plasma powers were characterized by scanning electron microscopy and gas permeation measurements. The deposition efficiencies of these cathodes were calculated based on the mass of the sprayed cathode. Particle surface temperatures were measured in-flight to enhance understanding of the relationship between spray parameters, microstructure, and deposition efficiency.

Plasma spraying of hard magnetic coatings based on Sm-Co alloys

International Nuclear Information System (INIS)

KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" data-affiliation=" (Siberian State Aerospace University named after Academician M.F. Reshetnev 31 KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" >Saunin, V N; KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" data-affiliation=" (Siberian State Aerospace University named after Academician M.F. Reshetnev 31 KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" >Telegin, S V

2015-01-01

Our research is focused on the formation of hard magnetic coatings by plasma spraying an arc-melted Sm-Co powder. We have studied basic magnetic characteristics depending on the components ratio in the alloy. A sample with a 40 wt.% Sm coating exhibits the highest coercive force (63 kOe) as compared to near-to-zero coercive force in the starting powder. X-ray structure analysis of the starting alloy and the coating reveals that the amount of SmCo 5 phase in the sprayed coating increases occupying up to 2/3 of the sample. We have also studied temperature dependence of the coating and have been able to obtain plasma sprayed permanent magnets operating within the temperature range from -100 to +500 °C. The technique used does not involve any additional thermal treatment and allows a coating to be formed right on the magnetic conductor surface irrespective of the conductor geometry

Relation between surface roughness and number of cathode spots of a low-pressure arc

International Nuclear Information System (INIS)

Sato, Atsushi; Iwao, Toru; Yumoto, Motoshige

2008-01-01

A remarkable characteristic of the cathode spot of a low-pressure arc is that it can remove an oxide layer preferentially. Recently, cathode spots of a low-pressure arc have been used for cleaning metal oxide surfaces before thermal spraying or surface modification. Nevertheless, few reports have described the cathode spot movement or the oxide removal process. This experiment was carried out using a Fe+C cathode workpiece and a cylindrical copper anode. The cathode spot movement was recorded using a high-speed video camera. The images were later analysed using plasma image processing. The workpiece surface, which was covered with a 9.67 μm thick oxide, was analysed using laser microscopy after processing. The surface roughness and the number of cathode spots showed no direct relation because the current density per cathode spot did not change according to the number of cathode spots.

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.

Feasibility of suspension spraying of yttria-stabilized zirconia with water-stabilized plasma torch

Czech Academy of Sciences Publication Activity Database

Mušálek, Radek; Bertolissi, Gabriele; Medřický, J.; Kotlan, Jiří; Pala, Zdeněk; Curry, N.

2015-01-01

Roč. 268, April (2015), s. 58-62 ISSN 0257-8972. [Rencontres Internationales de la Projection Thermique/6./. Limoges, 11.12.2013-13.12.2013] R&D Projects: GA ČR(CZ) GPP108/12/P552 Institutional support: RVO:61389021 Keywords : Thermal spray coating * Suspension spray ing * Thermal barrier coating * Water-stabilized plasma * High enthalpy plasma Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 2.139, year: 2015 http://www.sciencedirect.com/science/article/pii/S025789721400680X

Creep behavior of the titanium alloy with zirconia plasma sprayed coating

International Nuclear Information System (INIS)

Reis, D.A.P.; Moura Neto, C.; Couto, A.A.

2009-01-01

The proposal of this research has been the study of the plasma spayed coating on creep of the Ti-6Al-4V, focusing on the determination of the experimental parameters related to the first and second creep stages. Yttria (8 wt %) stabilized zirconia (YSZ) (Metco 204B-NS) with CoNiCrAlY ( AMDRY 995C) has been plasma sprayed coated on Ti-6Al-4V substrate. Creep tests with constant load had been done on Ti-6Al-4V coated samples, the stress level was from 250 to 319 MPa at 600 deg C. Highest values of t p and the decrease of the second stage rate had shown a better creep resistance on coated sample. Results indicate that the coated sample was greater than uncoated sample, thus the plasma sprayed coating prevent the sample oxidation efficiently. (author)

The effect of nozzle diameter, injection pressure and ambient temperature on spray characteristics in diesel engine

Science.gov (United States)

Rhaodah Andsaler, Adiba; Khalid, Amir; Sharifhatul Adila Abdullah, Nor; Sapit, Azwan; Jaat, Norrizam

2017-04-01

Mixture formation of the ignition process is a key element in the diesel combustion as it influences the combustion process and exhaust emission. Aim of this study is to elucidate the effects of nozzle diameter, injection pressure and ambient temperature to the formation of spray. This study investigated diesel formation spray using Computational Fluid Dynamics. Multiphase volume of fluid (VOF) behaviour in the chamber are determined by means of transient simulation, Eulerian of two phases is used for implementation of mixing fuel and air. The detail behaviour of spray droplet diameter, spray penetration and spray breakup length was visualised using the ANSYS 16.1. This simulation was done in different nozzle diameter 0.12 mm and 0.2 mm performed at the ambient temperature 500 K and 700 K with different injection pressure 40 MPa, 70 MPa and 140 MPa. Results show that high pressure influence droplet diameter become smaller and the penetration length longer with the high injection pressure apply. Smaller nozzle diameter gives a shorter length of the breakup. It is necessary for nozzle diameter and ambient temperature condition to improve the formation of spray. High injection pressure is most effective in improvement of formation spray under higher ambient temperature and smaller nozzle diameter.

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.

Production of ceramic formed parts by means of plasma spraying

International Nuclear Information System (INIS)

Kirner, K.

1989-01-01

Open and closed pipes and tubes, nozzles and crucibles, conical parts and other molded articles of ceramic materials such as aluminium oxide, magnesium-aluminium spinel, zirconium oxide, zirconium silicate and special ceramics can be fabricated by spray application to a core which is afterwards removed. Because at the same time these are mainly high temperature materials and high temperature application areas, plasma spraying is preferred. The process and examples of application are described, the advantages and disadvantages are pointed out. (orig.) [de

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.

Preparation and in vitro evaluation of plasma-sprayed bioactive akermanite coatings

International Nuclear Information System (INIS)

Yi, Deliang; Wu, Chengtie; Chang, Jiang; Ma, Xubing; Ji, Heng; Zheng, Xuebin

2012-01-01

Bioactive ceramic coatings on titanium (Ti) alloys play an important role in orthopedic applications. In this study, akermanite (Ca 2 MgSi 2 O 7 ) bioactive coatings are prepared through a plasma spraying technique. The bonding strength between the coatings and Ti-6Al-4V substrates is around 38.7–42.2 MPa, which is higher than that of plasma sprayed hydroxyapatite (HA) coatings reported previously. The prepared akermanite coatings reveal a distinct apatite-mineralization ability in simulated body fluid. Furthermore, akermanite coatings support the attachment and proliferation of rabbit bone marrow mesenchymal stem cells (BMSCs). The proliferation rate of BMSCs on akermanite coatings is obviously higher than that on HA coatings. (paper)

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

Laser-Based Spatio-Temporal Characterisation of Port Fuel Injection (PFI Sprays

Directory of Open Access Journals (Sweden)

C. T. N. Anand

2010-06-01

Full Text Available In the present work, detailed laser-based diagnostic experiments were conducted to characterise the spray from low pressure 2-hole and 4-hole Port Fuel Injection (PFI injectors. The main objective of the work included obtaining quantitative information of the spatio-temporal spray structure of such low-pressure gasoline sprays. A novel approach involving a combination of techniques such as Mie scattering, Granulometry, and Laser Sheet Dropsizing (LSD was used to study the spray structure. The droplet sizes, distributions with time, Sauter Mean Diameters (SMD, droplet velocities, cone angles and spray tip penetrations of the sprays from the injectors were determined. The spray from these injectors is found to be ‘pencil like’ and not dispersed as in high pressure sprays. The application of the above mentioned techniques provides two-dimensional SMD contours of the entire spray at different instants of time, with reasonable accuracy.

Heavy duty plasma spray gun

International Nuclear Information System (INIS)

Irons, G.C.; Klein, J.F.; Lander, R.D.; Thompson, H.C.; Trapani, R.D.

1984-01-01

A heavy duty plasma spray gun for extended industrial service is disclosed. The gun includes a gas distribution member made of a material having a coefficient of expansion different from that of the parts surrounding it. The gas distribution member is forcibly urged by a resilient member such as a coiled spring against a seal so as to assure the plasma gas is introduced into the gun arc in a manner only defined by the gas distribution member. The gun has liquid cooling for the nozzle (anode) and the cathode. Double seals are provided between the coolant and the arc region and a vent is provided between the seals which provides an indication when a seal has failed. Some parts of the gun are electrically isolated from others by an intermediate member which is formed as a sandwich of two rigid metal face pieces and an insulator disposed between them. The metal face pieces provide a rigid body to attach the remaining parts in proper alignment therewith

Phase stabilization in plasma sprayed BaTiO3

Czech Academy of Sciences Publication Activity Database

Ctibor, Pavel; Seiner, Hanuš; Sedláček, J.; Pala, Zdeněk; Vaněk, Přemysl

2013-01-01

Roč. 39, č. 5 (2013), s. 5039-5048 ISSN 0272-8842 R&D Projects: GA ČR(CZ) GA101/09/0702 Institutional support: RVO:61389021 ; RVO:61388998 ; RVO:68378271 Keywords : Spectroscopy * BaTiO3 * Plasma spraying * Spark plasma sintering Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass; BJ - Thermodynamics (UT-L); JH - Ceramics, Fire-Resistant Materials and Glass (FZU-D) Impact factor: 2.086, year: 2013 http://www.sciencedirect.com/science/article/pii/S0272884212013582

Global model analysis of negative ion generation in low-pressure inductively coupled hydrogen plasmas with bi-Maxwellian electron energy distributions

International Nuclear Information System (INIS)

Huh, Sung-Ryul; Kim, Nam-Kyun; Jung, Bong-Ki; Chung, Kyoung-Jae; Hwang, Yong-Seok; Kim, Gon-Ho

2015-01-01

A global model was developed to investigate the densities of negative ions and the other species in a low-pressure inductively coupled hydrogen plasma with a bi-Maxwellian electron energy distribution. Compared to a Maxwellian plasma, bi-Maxwellian plasmas have higher populations of low-energy electrons and highly vibrationally excited hydrogen molecules that are generated efficiently by high-energy electrons. This leads to a higher reaction rate of the dissociative electron attachment responsible for negative ion production. The model indicated that the bi-Maxwellian electron energy distribution at low pressures is favorable for the creation of negative ions. In addition, the electron temperature, electron density, and negative ion density calculated using the model were compared with the experimental data. In the low-pressure regime, the model results of the bi-Maxwellian electron energy distributions agreed well quantitatively with the experimental measurements, unlike those of the assumed Maxwellian electron energy distributions that had discrepancies

Observation of intense beam in low pressure from IPR Plasma Focus facility

International Nuclear Information System (INIS)

Kumar, R.; Shyam, A.; Chaturvedi, S.; Lathi, D.; Sarkar, Partha; Chaudhari, V.; Verma, R.; Shukla, R.; Debnath, K.; Sonara, J.; Shah, K.; Adhikary, B.

2004-01-01

Full text: Plasma focus (PF) is a powerful source of various ionizing radiation such as charged particles beam (ions and electrons), X-ray, neutrons etc. This device can operate from energy level of 50J to 1MJ. Plasma Focus is relatively small, simple and cheap in comparison with other radiation sources based on isotopes, accelerators and fusion reactors. Radiation pulse from PF is strong and very short. Now with the new pulsed power technology this device can be operated repeatedly with enhanced lifetime. All these features make plasma focus a versatile device for academic as well as industrial interest such as hot plasma physics and plasma collective processes, equation of state of matter under extreme conditions, material science including material characterization, dynamic equation control, and surface modification and destruction test. Intense burst of neutrons have been observed from a low energy (3.6 kJ) Mather type plasma focus device operated in 0.4 Torr pressure of deuterium medium at IPR. The emitted neutrons (10 9 /shot), that are accompanied by a strong hard X-ray pulse, were found to be having energy up to 3.26 MeV in the axial direction of the device

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

Science.gov (United States)

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

2018-04-01

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

Theoretical and experimental investigation of plasma and wave characteristics of coaxial discharges at low pressures

International Nuclear Information System (INIS)

Neichev, Z; Benova, E; Gamero, A; Sola, A

2006-01-01

The paper discusses a new configuration of the surface-wave sustained plasma - 'the coaxial structure'. The coaxial structure is investigated on the base of one-dimensional axial fluid model. That model is adequate enough for low pressure plasma, when the main process for charged particles production is the direct ionization from the ground state and the loss of electrons is due to diffusion to the wall. The role of the geometric factors is evaluated and discussed, varying the discharge conditions in the theoretical model. The main equations of the model - the local dispersion relation and the wave energy balance equation are obtained from Maxwell's equations with appropriate boundary conditions. The phase diagrams, the radial profiles of the electric field and the axial profiles of dimensionless electron number density, wave number, wave power are obtained at various plasma radii and dielectric tube thickness. The results are compared with those for the typical cylindrical plasma column at similar conditions. For the purpose of modelling at low pressure of a coaxial discharge sustained by a travelling electromagnetic wave, some important characteristics of the propagation of surface waves have been investigated experimentally. The axial profiles of the propagation coefficient and radial profiles of the electric field at different experimental conditions have been obtained and discussed

Influence of a powder feed rate on the properties of the plasma sprayed chromium carbide- 25% nickel chromium coating

Directory of Open Access Journals (Sweden)

Mihailo R. Mrdak

2014-04-01

Full Text Available Normal 0 false false false MicrosoftInternetExplorer4 The plasma spray process is a leading technology of powder depositing in the production of coatings widely used in the aerospace industry for the protection of new parts and for the repair of worn ones. Cermet 75Cr3C2 - 25Ni(Cr coatings based on Cr3C2 carbides are widely used to protect parts as they retain high values of hardness, strength and resistance to wear up to a temperature of 850°C. This paper discusses the influence of the parameters of the plasma spray deposition of 75Cr3C2 - 25Ni(Cr powder on the structure and mechanical properties of the coating. The powder is deposited using plasma spraying at atmospheric pressure (APS. The plasma gas is He, which is an inert gas and does not react with the powder; it produces dense plasma with lower heat content and less incorporated ambient air in the plasma jet thus reducing temperature decomposition and decarburization of Cr3C2 carbide.. In this study, three groups of coatings were deposited with three different powder feed rates of: 30, 45 and 60 g/min. The  coating with the best properties was deposited on the inlet flange parts of the turbo - jet engine TV2-117A to reduce the influence of vibrations and wear. The structures and the mechanical properties of 75Cr3C2 - 25Ni(Cr coatings are analyzed in accordance with the Pratt & Whitney standard. Studies have shown that powder feed rates have an important influence on the mechanical properties and structures of 75Cr3C2 - 25Ni(Cr coatings. 

Effect of aviation fuel type and fuel injection conditions on the spray characteristics of pressure swirl and hybrid air blast fuel injectors

Science.gov (United States)

Feddema, Rick

fuels. Optical patternation data and line of sight laser diffraction data show that there is significant difference between jet fuels. Particularly at low fuel injection pressures (0.345 MPa) and cold temperatures (-40 C), the patternation data shows that the total surface area in the spray at 38.1 mm from the pressure swirl injector for the JP-10 fuel type is one-sixth the amount of the JP-8. Finally, this study compares the atomizer performance of a pressure swirl nozzle to a hybrid air blast nozzle. The total surface area for both the hybrid air blast nozzle and the pressure swirl nozzle show a similar decline in atomization performance at low fuel injection pressures and cold temperatures. However, the optical patternator radial profile data and the line of sight laser diffraction data show that the droplet size and spray distribution data are less affected by injection conditions and fuel type in the hybrid air blast nozzle, than they are in the pressure swirl nozzle. One explanation is that the aerodynamic forces associated with the swirler on the hybrid air blast nozzle control the distribution droplets in the spray. This is in contrast to the pressure swirl nozzle droplet distribution that is controlled by internal geometry and droplet ballistics.

Experimental characterization of gasoline sprays under highly evaporating conditions

Science.gov (United States)

Khan, Muhammad Mahabat; Sheikh, Nadeem Ahmed; Khalid, Azfar; Lughmani, Waqas Akbar

2018-05-01

An experimental investigation of multistream gasoline sprays under highly evaporating conditions is carried out in this paper. Temperature increase of fuel and low engine pressure could lead to flash boiling. The spray shape is normally modified significantly under flash boiling conditions. The spray plumes expansion along with reduction in the axial momentum causes the jets to merge and creates a low-pressure area below the injector's nozzle. These effects initiate the collapse of spray cone and lead to the formation of a single jet plume or a big cluster like structure. The collapsing sprays reduces exposed surface and therefore they last longer and subsequently penetrate more. Spray plume momentum increase, jet plume reduction and spray target widening could delay or prevent the closure condition and limit the penetration (delayed formation of the cluster promotes evaporation). These spray characteristics are investigated experimentally using shadowgraphy, for five and six hole injectors, under various boundary conditions. Six hole injectors produce more collapsing sprays in comparison to five hole injector due to enhanced jet to jet interactions. The spray collapse tendency reduces with increase in injection pressure due high axial momentum of spray plumes. The spray evaporation rates of five hole injector are observed to be higher than six hole injectors. Larger spray cone angles of the six hole injectors promote less penetrating and less collapsing sprays.

Nonlinear Stress-Strain Behavior of Plasma Sprayed Ceramic Coatings

Czech Academy of Sciences Publication Activity Database

Nohava, Jiří; Kroupa, František

2005-01-01

Roč. 50, č. 3 (2005), s. 251-262 ISSN 0001-7043 R&D Projects: GA AV ČR KSK1010104 Institutional research plan: CEZ:AV0Z20430508 Keywords : plasma spraying * ceramic coatings * Young’s modulus * nonlinear behavior * microcracks Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

Plasma sprayed metal supported YSZ/Ni-LSGM-LSCF ITSOFC with nanostructured anode

Energy Technology Data Exchange (ETDEWEB)

Hwang, Changsing; Tsai, Chun-Huang; Lo, Chih-Hung; Sun, Cha-Hong [Physics Division, Institute of Nuclear Energy Research, Lungtan, Taoyuan 32546 (China)

2008-05-15

Intermediate temperature solid oxide fuel cells (ITSOFCs) supported by a porous Ni-substrate and based on Sr and Mg doped lanthanum gallate (LSGM) electrolyte, lanthanum strontium cobalt ferrite (LSCF) cathode and nanostructured yttria stabilized zirconia-nickel (YSZ/Ni) cermet anode have been fabricated successfully by atmospheric plasma spraying (APS). From ac impedance analysis, the sprayed YSZ/Ni cermet anode with a novel nanostructure and advantageous triple phase boundaries after hydrogen reduction has a low resistance. It shows a good electrocatalytic activity for hydrogen oxidation reactions. The sprayed LSGM electrolyte with {proportional_to}60 {mu}m in thickness and {proportional_to}0.054 S cm{sup -1} conductivity at 800 C shows a good gas tightness and gives an open circuit voltage (OCV) larger than 1 V. The sprayed LSCF cathode with {proportional_to}30 {mu}m in thickness and {proportional_to}30% porosity has a minimum resistance after being heated at 1000 C for 2 h. This cathode keeps right phase structure and good porous network microstructure for conducting electrons and negative oxygen ions. The APS sprayed cell after being heated at 1000 C for 2 h has a minimum inherent resistance and achieves output power densities of {proportional_to}440 mW cm{sup -2} at 800 C, {proportional_to}275 mW cm{sup -2} at 750 C and {proportional_to}170 mW cm{sup -2} at 700 C. Results from SEM, XRD, ac impedance analysis and I-V-P measurements are presented here. (author)

Plasma spraying of Fe-Cr-Al alloy powder

Czech Academy of Sciences Publication Activity Database

Voleník, Karel; Leitner, J.; Kolman, Blahoslav Jan; Písačka, Jan; Schneeweiss, Oldřich

2008-01-01

Roč. 46, č. 1 (2008), s. 17-25 ISSN 0023-432X R&D Projects: GA AV ČR IAA1041404 Institutional research plan: CEZ:AV0Z20430508; CEZ:AV0Z20410507 Keywords : Fe-Cr-Al alloy powder * plasma spraying * oxidation * vaporization * composition changes Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.345, year: 2007

Preventing Clogging In A Vacuum Plasma Spray Gun

Science.gov (United States)

Krotz, Phillip D.; Daniel, Ronald L., Jr.; Davis, William M.

1994-01-01

Modification of powder-injection ports enables lengthy, high-temperature deposition operations. Graphite inserts prevent clogging of ports through which copper powder injected into vacuum plasma spray (VPS) gun. Graphite liners eliminate need to spend production time refurbishing VPS gun, reducing cost of production and increasing productivity. Concept also applied to other material systems used for net-shape fabrication via VPS.

Effect of substrate and cathode parameters on the properties of suspension plasma sprayed solid oxide fuel cell electrolytes

Energy Technology Data Exchange (ETDEWEB)

Waldbillig, D.; Tang, Z.; Burgess, A. [British Columbia Univ., Vancouver, BC (Canada); Kesler, O. [Toronto Univ., ON (Canada)

2008-07-01

An axial injection suspension plasma spray system has been used to produce layers of fully stabilized yttriastabilized zirconia (YSZ) that could be used as solid oxide fuel cell (SOFC) electrolytes. Suspension plasma spraying is a promising technique for the rapid production of coatings with fine microstructures and controlled porosity without requiring a post-deposition heat treatment. This new manufacturing technique to produce SOFC active layers requires the build up of a number of different plasma sprayed SOFC functional layers (cathode, electrolyte and anode) sequentially on top of each other. To understand the influence of the substrate and previouslydeposited coating layers on subsequent coating layer properties, YSZ layers were deposited on top of plasma sprayed composite lanthanum strontium manganite (LSM)/YSZ cathode layers that were first deposited on porous ferritic stainless steel substrates. Three layer half cells consisting of the porous steel substrate, composite cathode, and suspension plasma sprayed electrolyte layer were then characterized. A systematic study was performed in order to investigate the effect of parameters such as substrate and cathode layer roughness, substrate surface pore size, and cathode microstructure and thickness on electrolyte deposition efficiency, cathode and electrolyte permeability, and layer microstructure. (orig.)

Effects of nozzle type and spray angle on spray deposition in ivy pot plants.

Science.gov (United States)

Foqué, Dieter; Nuyttens, David

2011-02-01

Fewer plant protection products are now authorised for use in ornamental growings. Frequent spraying with the same product or a suboptimal technique can lead to resistance in pests and diseases. Better application techniques could improve the sustainable use of the plant protection products still available. Spray boom systems--instead of the still predominantly used spray guns--might improve crop protection management in greenhouses considerably. The effect of nozzle type, spray pressure and spray angle on spray deposition and coverage in ivy pot plants was studied, with a focus on crop penetration and spraying the bottom side of the leaves in this dense crop. The experiments showed a significant and important effect of collector position on deposition and coverage in the plant. Although spray deposition and coverage on the bottom side of the leaves are generally low, they could be improved 3.0-4.9-fold using the appropriate application technique. When using a spray boom in a dense crop, the nozzle choice, spray pressure and spray angle should be well considered. The hollow-cone, the air-inclusion flat-fan and the standard flat-fan nozzle with an inclined spray angle performed best because of the effect of swirling droplets, droplets with a high momentum and droplet direction respectively. Copyright © 2010 Society of Chemical Industry.

Technological uses of low temperature plasmas

International Nuclear Information System (INIS)

Lawton, J.

1975-01-01

Types of low temperature plasma sources considered include; arc discharge, high pressure discharge, low pressure discharge and flame. The problems of uniform heating of a gas are discussed and it is considered that the most reliable technique is the magnetically rotated arc, but expanded discharges of one kind or another are likely to be serious competitors in the future. The uses of low temperature plasma in chemistry and combustion are considered. The potential for plasma chemistry lies with processes in which the reactions occur in the plasma itself or its neighbouring gas phase, including those which require the vaporization of liquefaction of a refractory material and also highly endothermic reactions. The production of thixotropic silica and acetylene are discussed as examples of such reactions. The field of plasma and combustion including; ignition, flame ionization and soot formation, and the MHD generator, is considered. (U.K.)

Influence of Powder Injection Parameters in High-Pressure Cold Spray

Science.gov (United States)

Ozdemir, Ozan C.; Widener, Christian A.

2017-10-01

High-pressure cold spray systems are becoming widely accepted for use in the structural repair of surface defects of expensive machinery parts used in industrial and military equipment. The deposition quality of cold spray repairs is typically validated using coupon testing and through destructive analysis of mock-ups or first articles for a defined set of parameters. In order to provide a reliable repair, it is important to not only maintain the same processing parameters, but also to have optimum fixed parameters, such as the particle injection location. This study is intended to provide insight into the sensitivity of the way that the powder is injected upstream of supersonic nozzles in high-pressure cold spray systems and the effects of variations in injection parameters on the nature of the powder particle kinetics. Experimentally validated three-dimensional computational fluid dynamics (3D CFD) models are implemented to study the particle impact conditions for varying powder feeder tube size, powder feeder tube axial misalignment, and radial powder feeder injection location on the particle velocity and the deposition shape of aluminum alloy 6061. Outputs of the models are statistically analyzed to explore the shape of the spray plume distribution and resulting coating buildup.

Deposition of nanostructured photocatalytic zinc ferrite films using solution precursor plasma spraying

International Nuclear Information System (INIS)

Dom, Rekha; Sivakumar, G.; Hebalkar, Neha Y.; Joshi, Shrikant V.; Borse, Pramod H.

2012-01-01

Highlights: ► Highly economic solution precursor route capable of producing films/coating even for mass scale production. ► Pure spinel phase ZnFe 2 O 4 porous, immobilized films deposited in single step. ► Parameter optimization yields access to nanostructuring in SPPS method. ► The ecofriendly immobilized ferrite films were active under solar radiation. ► Such magnetic system display advantage w.r.t. recyclability after photocatalyst extraction. -- Abstract: Deposition of pure spinel phase, photocatalytic zinc ferrite films on SS-304 substrates by solution precursor plasma spraying (SPPS) has been demonstrated for the first time. Deposition parameters such as precursor solution pH, concentration, film thickness, plasma power and gun-substrate distance were found to control physico-chemical properties of the film, with respect to their crystallinity, phase purity, and morphology. Alkaline precursor conditions (7 2 O 4 film. Very high/low precursor concentrations yielded mixed phase, less adherent, and highly inhomogeneous thin films. Desired spinel phase was achieved in as-deposited condition under appropriately controlled spray conditions and exhibited a band gap of ∼1.9 eV. The highly porous nature of the films favored its photocatalytic performance as indicated by methylene blue de-coloration under solar radiation. These immobilized films display good potential for visible light photocatalytic applications.

Functionally Graded Materials using Plasma Spray with Nano Structured Ceramic

International Nuclear Information System (INIS)

Sioh, E L; Tok, A I Y

2013-01-01

In this paper, nano structured FGM was fabricated using DC plasma spray technique. Nano structured and micro structured powder were used as the feeding powder with steel substrate. The spray parameters was optimized and characterisation of nano-ceramic FGM and micro-ceramic FGM were done using bending test and micro-hardness test. Experimental results have shown that the nano-structured FGM exhibit 20% improvement flexure strength and 10% in hardness. A comparison was made between sintered micro ceramic tile and nano ceramic FGM using simple drop test method.

The structure and thermal properties of plasma-sprayed beryllium for the International Thermonuclear Experimental Reactor (ITER)

International Nuclear Information System (INIS)

Castro, R.G.; Bartlett, A.; Elliott, K.E.; Hollis, K.J.

1996-01-01

Plasma spraying is being studied for in situ repair of damaged Be and W plasma facing surfaces for ITER, the next generation magnetic fusion energy device, and is also being considered for fabricating Be and W plasma-facing components for the first wall of ITER. Investigators at LANL's Beryllium Atomization and Thermal Spray Facility have concentrated on investigating the structure-property relation between as-deposited microstructures of plasma sprayed Be coatings and resulting thermal properties. In this study, the effect of initial substrate temperature on resulting thermal diffusivity of Be coatings and the thermal diffusivity at the coating/Be substrate interface (interface thermal resistance) was investigated. Results show that initial Be substrate temperatures above 600 C can improve the thermal diffusivity of the Be coatings and minimize any thermal resistance at the interface between the Be coating and Be substrate

Equivalent effect of neutral gas pressure and transverse magnetic field in low-pressure glow discharge plasma

International Nuclear Information System (INIS)

Toma, M.; Rusu, Ioana; Pohoata, V.; Mihaila, I.

2001-01-01

In the paper it is emphasized the equivalent effect of the neutral gas pressure and the action of a transverse magnetic field (TMF), respectively, on a striated positive plasma column. Experimental and theoretical results prove that the distance between striations has the same variation under the influence of both neutral gas pressure and the action of TMF. The pressure modification as well as the action of a TMF can induce ionization instability in the plasma column which explains the standing striation appearance. (authors)

Development of suspension plasma sprayed alumina coatings with high enthalpy plasma torch

Czech Academy of Sciences Publication Activity Database

Tesař, Tomáš; Mušálek, Radek; Medřický, Jan; Kotlan, Jiří; Lukáč, František; Pala, Zdeněk; Ctibor, Pavel; Chráska, Tomáš; Houdková, Š.; Rimal, V.; Curry, N.

2017-01-01

Roč. 325, September (2017), s. 277-288 ISSN 0257-8972 R&D Projects: GA ČR GA15-12145S Institutional support: RVO:61389021 Keywords : Suspension plasma spraying * Aluminium oxide * Mechanical properties * Hardness * Adhesion * Wear resistance Subject RIV: JK - Corrosion ; Surface Treatment of Materials OBOR OECD: Coating and films Impact factor: 2.589, year: 2016 http://www.sciencedirect.com/science/article/pii/S0257897217306424

GDI fuel sprays of light naphtha, PRF95 and gasoline using a piezoelectric injector under different ambient pressures

KAUST Repository

Wu, Zengyang; Wang, Libing; Badra, Jihad A.; Roberts, William L.; Fang, Tiegang

2018-01-01

This study investigates fuel sprays of light naphtha (LN), primary reference fuel (PRF) and gasoline under different ambient pressures with an outwardly opening piezo gasoline direct injection (GDI) fuel injector. The tested gasoline fuel (regular grade with up to 10% ethanol, E10) was obtained by mixing fuels with AKI (the average of the research octane number (RON) and the motor octane number (MON)) of 87 from three local gas stations. Primary reference fuel (PRF) is commonly used as gasoline surrogate fuel and is blended by iso-octane and n-heptane. PRF95 is the blend of 95% iso-octane and 5% n-heptane by volume. LN fuel was provided by Saudi Aramco Oil Company. Five different ambient pressure conditions varied from 1 bar to 10 bar were tested. The spray was visualized by applying a Mie-scattering technique and a high-speed camera was employed to capture the spray images. The spray structure, spray angle, spray penetration length and spray front fluctuation were analyzed and compared among three fuels. Spray images show that a clear filamentary hollow-cone spray structure is formed for all three fuels at atmospheric conditions, and toroidal recirculation vortexes are observed at the downstream spray edges. A higher ambient pressure leads to a stronger vortex located closer to the injector outlet. Generally speaking, larger spray angles are found under higher ambient pressure conditions for all three fuels. Gasoline fuel always has the largest spray angle for each ambient pressure, while PRF95 has the smallest at most time. For each fuel, the spray front penetration length and spray front penetration velocity decrease with increasing ambient pressure. LN, PRF95 and gasoline show similar penetration length and velocity under the tested conditions. A two-stage spray front fluctuation pattern is observed for all three fuels. Stage one begins from the start of the injection and ends at 450–500 μs after the start of the injection trigger (ASOIT) with a slow

GDI fuel sprays of light naphtha, PRF95 and gasoline using a piezoelectric injector under different ambient pressures

KAUST Repository

Wu, Zengyang

2018-03-20

This study investigates fuel sprays of light naphtha (LN), primary reference fuel (PRF) and gasoline under different ambient pressures with an outwardly opening piezo gasoline direct injection (GDI) fuel injector. The tested gasoline fuel (regular grade with up to 10% ethanol, E10) was obtained by mixing fuels with AKI (the average of the research octane number (RON) and the motor octane number (MON)) of 87 from three local gas stations. Primary reference fuel (PRF) is commonly used as gasoline surrogate fuel and is blended by iso-octane and n-heptane. PRF95 is the blend of 95% iso-octane and 5% n-heptane by volume. LN fuel was provided by Saudi Aramco Oil Company. Five different ambient pressure conditions varied from 1 bar to 10 bar were tested. The spray was visualized by applying a Mie-scattering technique and a high-speed camera was employed to capture the spray images. The spray structure, spray angle, spray penetration length and spray front fluctuation were analyzed and compared among three fuels. Spray images show that a clear filamentary hollow-cone spray structure is formed for all three fuels at atmospheric conditions, and toroidal recirculation vortexes are observed at the downstream spray edges. A higher ambient pressure leads to a stronger vortex located closer to the injector outlet. Generally speaking, larger spray angles are found under higher ambient pressure conditions for all three fuels. Gasoline fuel always has the largest spray angle for each ambient pressure, while PRF95 has the smallest at most time. For each fuel, the spray front penetration length and spray front penetration velocity decrease with increasing ambient pressure. LN, PRF95 and gasoline show similar penetration length and velocity under the tested conditions. A two-stage spray front fluctuation pattern is observed for all three fuels. Stage one begins from the start of the injection and ends at 450–500 μs after the start of the injection trigger (ASOIT) with a slow

Highly ionized physical vapor deposition plasma source working at very low pressure

Science.gov (United States)

Stranak, V.; Herrendorf, A.-P.; Drache, S.; Cada, M.; Hubicka, Z.; Tichy, M.; Hippler, R.

2012-04-01

Highly ionized discharge for physical vapor deposition at very low pressure is presented in the paper. The discharge is generated by electron cyclotron wave resonance (ECWR) which assists with ignition of high power impulse magnetron sputtering (HiPIMS) discharge. The magnetron gun (with Ti target) was built into the single-turn coil RF electrode of the ECWR facility. ECWR assistance provides pre-ionization effect which allows significant reduction of pressure during HiPIMS operation down to p = 0.05 Pa; this is nearly more than an order of magnitude lower than at typical pressure ranges of HiPIMS discharges. We can confirm that nearly all sputtered particles are ionized (only Ti+ and Ti++ peaks are observed in the mass scan spectra). This corresponds well with high plasma density ne ˜ 1018 m-3, measured during the HiPIMS pulse.

Highly ionized physical vapor deposition plasma source working at very low pressure

International Nuclear Information System (INIS)

Stranak, V.; Herrendorf, A.-P.; Drache, S.; Hippler, R.; Cada, M.; Hubicka, Z.; Tichy, M.

2012-01-01

Highly ionized discharge for physical vapor deposition at very low pressure is presented in the paper. The discharge is generated by electron cyclotron wave resonance (ECWR) which assists with ignition of high power impulse magnetron sputtering (HiPIMS) discharge. The magnetron gun (with Ti target) was built into the single-turn coil RF electrode of the ECWR facility. ECWR assistance provides pre-ionization effect which allows significant reduction of pressure during HiPIMS operation down to p = 0.05 Pa; this is nearly more than an order of magnitude lower than at typical pressure ranges of HiPIMS discharges. We can confirm that nearly all sputtered particles are ionized (only Ti + and Ti ++ peaks are observed in the mass scan spectra). This corresponds well with high plasma density n e ∼ 10 18 m -3 , measured during the HiPIMS pulse.

Simulation of Spray Injection in the Pressurizer Using RELAP5

Directory of Open Access Journals (Sweden)

S. Dibyo

2017-08-01

Full Text Available A modeling research using Relap5 to assess the pressurizer of a pressurized water reactor(PWR power plant has been performed. The heater and water injection systems in the pressurizer system of the PWRare of greatimportance for system pressure control.The heater is designed to increase the pressure while the water sprayer injection is to perform depressurization. Most of studies conducted in the past mainly focused on determining the effects of nozzle spray design and droplet size using testing loops. The purpose of this simulation is to analyze the spray injection flow rate against the pressure characteristics of the pressurizer using RELAP5. Through this approach, the optimum injection flow rate of full scale plant pressurizer can be analyzed. The parameters investigated are pressure and temperature.In RELAP5, the pressurizer tank wasmodeled with six volume nodes and the heater was modeled by using heat structure. In the model, the sprayer takes water from the cold leg to inject it into the top of tank region.The resultsshowedthat the mass flow of about 4 kg/s is the mosteffectivevalueto limit pressure in the pressurizer to below 15.7 MPa. However, the flow rates of 8 kg/s and more cause overpressure. This simulation is usefulto complement the data related to the water flow rate injection systems of the pressurizer. Normal 0 false false false EN-US X-NONE X-NONE

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