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Sample records for macroscopic spray behavior

  1. Macroscopic and microscopic characteristics of a fuel spray impinged on the wall

    NASA Astrophysics Data System (ADS)

    Park, Sung Wook; Lee, Chang Sik

    2004-11-01

    An experimental study was performed to investigate the macroscopic behavior and atomization characteristics of a high-speed diesel spray impinged on the wall at various injection and impinging conditions. The development processes of sprays impinged on the wall were visualized using the spray visualization system composed of a Nd:YAG laser and an intensified charge-coupled device (ICCD) camera. The atomization characteristics of the impinged spray on the wall were also explored in terms of mean droplet diameter and velocity distributions by using a phase Doppler particle analyzer (PDPA) system. The results provide the effects of injection parameters, wall conditions, and the other various experimental conditions on the macroscopic behavior and atomization characteristics of the impinged sprays on the wall.

  2. Particle Behavior During the Arc Spraying Process with Cored Wires

    NASA Astrophysics Data System (ADS)

    Tillmann, W.; Vogli, E.; Abdulgader, M.; Gurris, M.; Kuzmin, D.; Turek, S.

    2008-12-01

    To use the manifold possibilities that arc spraying offers to deposit wear resistance layers, knowledge of the particle formation and their behavior is necessary. This work is focused on studying the particle properties during arc spraying with cored wires. Different cored wires under various spraying parameters are investigated by means of a high speed camera. Particle properties in-flight, such as velocity and temperature, are determined. Correlation between particle behavior and particle characteristics at different spraying conditions is established. At the same time, the particle-laden gas flow is simulated numerically and the computed solutions are used to illustrate the utility of the proposed CFD model and compared with experimental results. The employed mathematical model represents a system of macroscopic conservation laws for the continuous gas phase and for the gas-solid mixture. This approach formulation makes it possible to circumvent the numerical difficulties associated with the implementation of a (potentially ill-posed) two-fluid model. The discretization in space is performed using a high-resolution finite element scheme based on algebraic flux correction in terms of local characteristic variables. The artificial diffusion operator is constructed on the discrete level and fitted to the local solution behavior using a multidimensional flux limiter of TVD type.

  3. The behavior of a macroscopic granular material in vortex flow

    NASA Astrophysics Data System (ADS)

    Nishikawa, Asami

    A granular material is defined as a collection of discrete particles such as powder and grain. Granular materials display a large number of complex behaviors. In this project, the behavior of macroscopic granular materials under tornado-like vortex airflow, with varying airflow velocity, was observed and studied. The experimental system was composed of a 9.20-cm inner diameter acrylic pipe with a metal mesh bottom holding the particles, a PVC duct, and an airflow source controlled by a variable auto-transformer, and a power-meter. A fixed fan blade was attached to the duct's inner wall to create a tornado-like vortex airflow from straight flow. As the airflow velocity was increased gradually, the behavior of a set of same-diameter granular materials was observed. The observed behaviors were classified into six phases based on the macroscopic mechanical dynamics. Through this project, we gained insights on the significant parameters for a computer simulation of a similar system by Heath Rice [5]. Comparing computationally and experimentally observed phase diagrams, we can see similar structure. The experimental observations showed the effect of initial arrangement of particles on the phase transitions.

  4. Spray Behavior and Atomization Characteristics of Biodiesel

    NASA Astrophysics Data System (ADS)

    Choi, Seung-Hun; Oh, Young-Taig

    Biodiesel has large amount of oxygen in itself, which make it very efficient in reducing exhaust emission by improving combustion inside an engine. But biodiesel has a low temperature flow problem because it has a high viscosity. In this study, the spray behavior and atomization characteristics were investigated to confirm of some effect for the combination of non-esterification biodiesel and fuel additive WDP and IPA. The process of spray was visualized through the visualization system composed of a halogen lamp and high speed camera, and atomization characteristics were investigated through LDPA. When blending WDP and IPA with biodiesel, atomization and spray characteristics were improved. Through this experimental result, SMD of blended fuel, WDP 25% and biodiesel 75%, was 33.9% reduced at distance 6cm from a nozzle tip under injection pressure 30MPa.

  5. Macroscopic Behavior of Nematics with D2d Symmetry

    NASA Astrophysics Data System (ADS)

    Pleiner, Harald; Brand, Helmut R.

    2010-03-01

    We discuss the symmetry properties and the macroscopic behavior of a nematic liquid crystal phase with D2d symmetry. Such a phase is a prime candidate for nematic phases made from banana-shaped molecules where the usual quadrupolar order coexists with octupolar (tetrahedratic) order. The resulting nematic phase is non-polar. While this phase could resemble the classic D∞h nematic in the polarizing microscope, it has many static as well as reversible and irreversible properties unknown to non-polar nematics without octupolar order. In particular, there is a linear gradient term in the free energy that selects parity leading to ambidextrously helical ground states when the molecules are achiral. In addition, there are static and irreversible coupling terms of a type only met otherwise in macroscopically chiral liquid crystals, e.g. the ambidextrous analogues of Lehmann-type effects known from cholesteric liquid crystals. Finally, we discuss certain nonlinear aspects of the dynamics related to the non-commutativity of three-dimensional finite rotations as well as other structural nonlinear hydrodynamic effects.

  6. Influence of aircraft vortices on spray cloud behavior.

    PubMed

    Mickle, R E

    1996-06-01

    For small droplet spraying, the spray cloud is initially entrained into the wingtip vortices so that the ultimate fate of the spray is controlled by the motion of these vortices. In close to 100 aerial sprays, the emitted spray cloud has been mapped using a scanning laser system that displays diffusion and transport of the spray cloud. Results detailing the concentrations within the spray cloud in space and time are given for sprays in parallel and crosswinds. Wind direction is seen to potentially alter the vortex motion and hence the fate of the spray cloud. In crosswind spraying, the vortex behavior associated with the 2 wings is found to differ, which leads to enhanced deposition from the upwind wing and enhanced drift from the downwind wing.

  7. Macroscopic behavior and microscopic magnetic properties of nanocarbon

    NASA Astrophysics Data System (ADS)

    Lähderanta, E.; Ryzhov, V. A.; Lashkul, A. V.; Galimov, D. M.; Titkov, A. N.; Matveev, V. V.; Mokeev, M. V.; Kurbakov, A. I.; Lisunov, K. G.

    2015-06-01

    Here are presented investigations of powder and glass-like samples containing carbon nanoparticles, not intentionally doped and doped with Ag, Au and Co. The neutron diffraction study reveals an amorphous structure of the samples doped with Au and Co, as well as the magnetic scattering due to a long-range FM order in the Co-doped sample. The composition and molecular structure of the sample doped with Au is clarified with the NMR investigations. The temperature dependence of the magnetization, M (T), exhibits large irreversibility in low fields of B=1-7 mT. M (B) saturates already above 2 T at high temperatures, but deviates from the saturation behavior below ~50 (150 K). Magnetic hysteresis is observed already at 300 K and exhibits a power-law temperature decay of the coercive field, Bc (T). The macroscopic behavior above is typical of an assembly of partially blocked magnetic nanoparticles. The values of the saturation magnetization, Ms, and the blocking temperature, Tb, are obtained as well. However, the hysteresis loop in the Co-doped sample differs from that in other samples, and the values of Bc and Ms are noticeably increased.

  8. Effective macroscopic adhesive contact behavior induced by small surface roughness

    NASA Astrophysics Data System (ADS)

    Kesari, Haneesh; Lew, Adrian J.

    2011-12-01

    In this paper we study a model contact problem involving adhesive elastic frictionless contact between rough surfaces. The problem's most notable feature is that it captures the phenomenon of depth-dependent-hysteresis (DDH) (e.g., see Kesari et al., 2010), which refers to the observation of different contact forces during the loading and unloading stages of a contact experiment. We specifically study contact between a rigid axi-symmetric punch and an elastic half-space. The roughness is represented as arbitrary periodic undulations in the punch's radial profile. These undulations induce multiple equilibrium contact regions between the bodies at each indentation-depth. Assuming that the system evolves so as to minimize its potential energy, we show that different equilibrium contact regions are selected during the loading and unloading stages at each indentation-depth, giving rise to DDH. When the period and amplitude of our model's roughness is reduced, we show that the evolution of the contact force and radius with the indentation-depth can be approximated with simpler curves, the effective macroscopic behavior, which we compute. Remarkably, the effective behavior depends solely on the amplitude and period of the model's roughness. The effective behavior is useful for estimating material properties from contact experiments displaying DDH. We show one such example here. Using the effective behavior for a particular roughness model (sinusoidal) we analyze the energy loss during a loading/unloading cycle, finding that roughness can toughen the interface. We also estimate the energy barriers between the different equilibrium contact regions at a fixed indentation-depth, which can be used to assess the importance of ambient energy fluctuations on DDH.

  9. Dilation Behavior of Thermal Spray Coatings

    NASA Astrophysics Data System (ADS)

    Bejarano Lopez, Miryan Lorena

    Thermal Spray (TS) is a very versatile manufacturing process to deposit thick coatings on a variety of substrates. Coatings are used in protective (i.e. wear, chemical attack, high temperature, etc.) and functional (i.e. sensors) applications. TS coatings have a unique lamellar microstructure as a result of the overlapping of millions of molten and partially-molten particles. During processing, high deformation by impact, high temperature, and rapid solidification lead to a complex hierarchical material system that contains a high amount of microstructural defects. The presence of defects in the microstructure contribute to differences in property values in comparison to bulk materials. Thermal stresses and residual strains arise from processing, thermal gradients and thermal exposure. Evaluation of thermal properties, in this case, the coefficient of thermal expansion (CTE) is of vital importance to enhance coating performance. In this dissertation, expansion measurements of various metals, alloys, ceramics, and cermet coatings; were carried out using various techniques (push rod dilatometry, x-ray diffraction XRD, digital image correlation DIC, and curvature method) to determine the dilation behavior at the atomic, micro- and macro-scale levels. The main results were. 1) Mathematical models (Turner and Kerner) used for composite materials, successfully predicted the CTE property of a TS coating where the primary phase is the coating material and the secondary phases can be oxides, precipitates, etc. (formed as a byproduct of the spraying process). CTE was found not to be affected by porosity. 2) Despite the anisotropic behavior characteristic of TS coatings, the experimental results shown that CTE results to be reasonable isotropic within the scope of this study. 3) The curvature method was found to be an alternative technique to obtain the CTE, as well as the Young's modulus of coating in a bi-material strip, with good approximation. 4) An anomalous expansion

  10. Representation of the vaporization behavior of turbulent polydisperse sprays by equivalent monodisperse sprays

    NASA Technical Reports Server (NTRS)

    Aggarwal, S. K.; Shuen, J. S.

    1986-01-01

    The concept of using an equivalent monodisperse spray to represent the vaporization behavior of polydisperse sprays has been examined by numerically solving two turbulent vaporizing sprays. One involves the injection of Freon-11 in a still environment, whereas the other is a methanol spray in a still but hot environment. The use of three different mean sizes, namely, Sauter mean diameter, volume median diameter, and surface-area mean diameter, has been investigated. Results indicate a good degree of correlation between the polydisperse spray and its equivalent monodisperse sprays represented by the volume median diameter and the Sauter mean diameter, the former giving slightly better results. The surface-area mean diameter does not provide as good a correlation as the other two mean diameters.

  11. Representation of the vaporization behavior of turbulent polydisperse sprays by 'equivalent' monodisperse sprays

    NASA Technical Reports Server (NTRS)

    Aggarwal, S. K.; Shuen, J. S.

    1987-01-01

    The concept of using an equivalent monodisperse spray to represent the vaporization behavior of polydisperse sprays has been examined by numerically solving two turbulent vaporizing sprays. One involves the injection of Freon-11 in a still environment, whereas the other is a methanol spray in a still but hot environment. The use of three different mean sizes, namely, Sauter mean diameter, volume median diameter, and surface-area mean diameter, has been investigated. Results indicate a good degree of correlation between the polydisperse spray and its equivalent monodisperse sprays represented by the volume median diameter and the Sauter mean diameter, the former giving slightly better results. The surface-area mean diameter does not provide as good a correlation as the other two mean diameters.

  12. Comparision on dynamic behavior of diesel spray and rapeseed oil spray in diesel engine

    NASA Astrophysics Data System (ADS)

    Sapit, Azwan; Azahari Razali, Mohd; Faisal Hushim, Mohd; Jaat, Norrizam; Nizam Mohammad, Akmal; Khalid, Amir

    2017-04-01

    Fuel-air mixing is important process in diesel combustion. It significantly affects the combustion and emission of diesel engine. Biomass fuel has high viscosity and high distillation temperature and may negatively affect the fuel-air mixing process. Thus, study on the spray development and atomization of this type of fuel is important. This study investigates the atomization characteristics and droplet dynamic behaviors of diesel engine spray fuelled by rapeseed oil (RO) and comparison to diesel fuel (GO). Optical observation of RO spray was carried out using shadowgraph photography technique. Single nano-spark photography technique was used to study the characteristics of the spray while dual nano-spark shadowgraph technique was used to study the spray droplet behavior. Using in-house image processing algorithm, the images were processed and the boundary condition of each spray was also studied. The results show that RO has very poor atomization due to the high viscosity nature of the fuel when compared to GO. This is in agreement with the results from spray droplet dynamic behavior studies that shows due to the high viscosity, the RO spray droplets are large in size and travel downward, with very little influence of entrainment effect due to its large kinematic energy.

  13. A quantitative link between microplastic instability and macroscopic deformation behaviors in metallic glasses

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Chen, G. L.; Hui, X. D.; Liu, C. T.; Lin, Y.; Shang, X. C.; Lu, Z. P.

    2009-10-01

    Based on mechanical instability of individual shear transformation zones (STZs), a quantitative link between the microplastic instability and macroscopic deformation behavior of metallic glasses was proposed. Our analysis confirms that macroscopic metallic glasses comprise a statistical distribution of STZ embryos with distributed values of activation energy, and the microplastic instability of all the individual STZs dictates the macroscopic deformation behavior of amorphous solids. The statistical model presented in this paper can successfully reproduce the macroscopic stress-strain curves determined experimentally and readily be used to predict strain-rate effects on the macroscopic responses with the availability of the material parameters at a certain strain rate, which offer new insights into understanding the actual deformation mechanism in amorphous solids.

  14. Pesticide spray application, behavior, and assessment: workshop proceedings

    Treesearch

    Richard B. Roberts

    1976-01-01

    Experts from relevant disciplines exchanged information on three important problems of pesticide spray technology. The four papers presented are Physical Parameters Relating to Pesticide Applications by N. B. Akesson and W. E. Yates; The Micrometeorology and Physics of Spray Particle Behavior by H. E. Cramer and D. G. Boyle;

  15. Corrosion behavior of magnetic ferrite coating prepared by plasma spraying

    SciTech Connect

    Liu, Yi; Wei, Shicheng Tong, Hui; Tian, Haoliang; Liu, Ming; Xu, Binshi

    2014-12-15

    Graphical abstract: The saturation magnetization (M{sub s}) of the ferrite coating is 34.417 emu/g while the M{sub s} value of the ferrite powder is 71.916 emu/g. It can be seen that plasma spray process causes deterioration of the room temperature soft magnetic properties. - Highlights: • Spinel ferrite coatings have been prepared by plasma spraying. • The coating consists of nanocrystalline grains. • The saturation magnetization of the ferrite coating is 34.417 emu/g. • Corrosion behavior of the ferrite coating was examined in NaCl solution. - Abstract: In this study, spray dried spinel ferrite powders were deposited on the surface of mild steel substrate through plasma spraying. The structure and morphological studies on the ferrite coatings were carried out using X-ray diffraction, scanning electron microscope and Raman spectroscopy. It was showed that spray dried process was an effective method to prepare thermal spraying powders. The coating showed spinel structure with a second phase of LaFeO{sub 3}. The magnetic property of the ferrite samples were measured by vibrating sample magnetometer. The saturation magnetization (M{sub s}) of the ferrite coating was 34.417 emu/g. The corrosion behavior of coating samples was examined by electrochemical impedance spectroscopy. EIS diagrams showed three corrosion processes as the coating immersed in 3.5 wt.% NaCl solution. The results suggested that plasma spraying was a promising technology for the production of magnetic ferrite coatings.

  16. Collective behavior of active Brownian particles: From microscopic clustering to macroscopic phase separation

    NASA Astrophysics Data System (ADS)

    Speck, Thomas

    2016-11-01

    A pedagogical introduction to the analytical treatment of the collective behavior of active (self-propelled) Brownian particles with short-ranged interactions is presented. The treatment is based on established concepts from the theories of simple liquids and pattern formation. It is shown how microscopic clustering due to self-blocking of directed particle motion leads to macroscopic phase separation described by effective equilibrium concepts holding on length scales larger than the persistence length of the direction motion.

  17. The use of a macroscopic formulation describing the effects of dynamic compaction and porosity on plasma sprayed copper

    SciTech Connect

    Arrigoni, M.; Boustie, M.; Bolis, C.; Berthe, L.; Barradas, S.; Jeandin, M.

    2008-04-15

    Coatings processed by thermal deposition techniques involve porosity. The Laser adhesion test developed for testing bond strength of a coating on its substrate requires a good knowledge of shock wave propagation in such media. Experiments carried out on plasma sprayed copper samples, about 14% porous, with velocity interferometer system for any reflector measurements display the discrepancy of previously used models. Hence, a one-dimensional formulation of the compaction process, based on a simple P-{alpha} model, is proposed to improve the correlation between experimental and computed data signals obtained on a plasma sprayed copper under dynamic loading. Besides, this improvement allows the estimation of the bond strength of a plasma sprayed copper on aluminum substrate.

  18. Inflight Particle Behavior in the Vacuum Kinetic Spray Process

    NASA Astrophysics Data System (ADS)

    Park, Hyungkwon; Kwon, Hansol; Lee, Changhee

    2017-08-01

    The vacuum kinetic spray (VKS) process, also-called aerosol deposition, is a promising spray technology by which a thin or thick film can be fabricated at room temperature. Although a number of relevant studies have been performed, almost all have focused on the development of various applications, and unfortunately, the deposition mechanism has not yet been clarified. In this respect, the particle velocity in the flow field in VKS is investigated as a first stage of research into the VKS deposition mechanism. In this research, after a simulation prototype was derived based on the experimental results, the particle average and impact velocities were estimated. In addition, the change in particle velocities with gas flow rates, particle size, and working distance was analyzed based on simulation analyses and microstructural evidence. As a result, the gas flow rate, particle size, and working distance affect the particle impact velocity and further deposition behavior and film microstructure.

  19. Inflight Particle Behavior in the Vacuum Kinetic Spray Process

    NASA Astrophysics Data System (ADS)

    Park, Hyungkwon; Kwon, Hansol; Lee, Changhee

    2017-10-01

    The vacuum kinetic spray (VKS) process, also-called aerosol deposition, is a promising spray technology by which a thin or thick film can be fabricated at room temperature. Although a number of relevant studies have been performed, almost all have focused on the development of various applications, and unfortunately, the deposition mechanism has not yet been clarified. In this respect, the particle velocity in the flow field in VKS is investigated as a first stage of research into the VKS deposition mechanism. In this research, after a simulation prototype was derived based on the experimental results, the particle average and impact velocities were estimated. In addition, the change in particle velocities with gas flow rates, particle size, and working distance was analyzed based on simulation analyses and microstructural evidence. As a result, the gas flow rate, particle size, and working distance affect the particle impact velocity and further deposition behavior and film microstructure.

  20. Anti-icing Behavior of Thermally Sprayed Polymer Coatings

    NASA Astrophysics Data System (ADS)

    Koivuluoto, Heli; Stenroos, Christian; Kylmälahti, Mikko; Apostol, Marian; Kiilakoski, Jarkko; Vuoristo, Petri

    2017-01-01

    Surface engineering shows an increasing potential to provide a sustainable approach to icing problems. Currently, several passive anti-ice properties adoptable to coatings are known, but further research is required to proceed for practical applications. This is due to the fact that icing reduces safety, operational tempo, productivity and reliability of logistics, industry and infrastructure. An icing wind tunnel and a centrifugal ice adhesion test equipment can be used to evaluate and develop anti-icing and icephobic coatings for a potential use in various arctic environments, e.g., in wind power generation, oil drilling, mining and logistic industries. The present study deals with evaluation of icing properties of flame-sprayed polyethylene (PE)-based polymer coatings. In the laboratory-scale icing tests, thermally sprayed polymer coatings showed low ice adhesion compared with metals such as aluminum and stainless steel. The ice adhesion strength of the flame-sprayed PE coating was found to have approximately seven times lower ice adhesion values compared with metallic aluminum, indicating a very promising anti-icing behavior.

  1. Sea water corrosion behavior of plasma sprayed abradable coatings

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

    Aluminum based abradable coating is used for sealing purpose in compressor casing of aero engines to withstand up to a service temperature of 450°C. Al-BNSiO2 composite coating is deposited using thermal plasma spray technique. Coating thickness measured and porosity of the coating is evaluated.Coating morphology is observed and EDSanalysis is done with SEM (Jeol make). The effect of time on the sea water corrosion behavior of the coating is evaluated. It is observed that, there is a sharp increase in weight gain of the coating up to six weeks of immersion. This behavior is attributed to the adsorption/deposition of other elements/reactions taking place during interaction with sea water.

  2. The macroscopic behavior of cumulus ensembles simulated by a cumulus ensemble model

    SciTech Connect

    Kuan-Man Xu; Akio Arakawa; Krueger, S.K. )

    1992-12-15

    The two-dimensional UCLA cumulus ensemble model (CEM), which covers a large horizontal area with a sufficiently small horizontal grid size, is used in this study. A number of simulation experiments are performed with the CEM to study the macroscopic behavior of cumulus convection under a variety of different large-scale and underlying surface conditions. Specifically, the modulation of cumulus activity by the imposed large-scale processes and the eddy kinetic energy (EKE) budget are investigated in detail. In all simulations, cumulus convection is rather strongly modulated by large-scale advective processes in spite of the existence of some nonmodulated high-frequency fluctuations. The modulation exhibits some phase delays, however, when the basic wind shear is strong. This is presumably associated with the existence of mesoscale convective organization. The EKE budget analysis shows that the net eddy buoyancy generation rate is nearly zero for a wide range of cumulus ensembles. 34 refs., 17 figs., 2 tabs.

  3. Macroscopic behavior of a bar undergoing the paraelectric-ferroelectric phase transformation

    NASA Astrophysics Data System (ADS)

    Jiang, Qing

    1993-10-01

    R ECENT WORK of the author has developed a continuum model for the paraelectric—ferroelectric phase transformation. The present paper describes the detailed implications of this model when it has been supplemented with constitutive information pertaining to the phase transformation. An explicit Helmholtz potential has been constructed to characterize a hypothetical crystal capable of undergoing the paraelectric-ferroelectric phase transformation under the influence of applied electric fields or thermomechanical loads. The hysteretic macroscopic behavior associated with the phase transformation, induced by variation of temperature, application of electric fields and mechanical loads, has been studied. Some of the predictions have been compared qualitatively with experimental observations. The entire analysis is carried out within a one-dimensional setting.

  4. Safety of epidural administration of Osteogenic Protein-1 (OP-1/BMP-7): behavioral and macroscopic observation.

    PubMed

    Kawakami, Mamoru; Hashizume, Hiroshi; Matsumoto, Takuji; Enyo, Yoshio; Okada, Motohiro; Yoshida, Munehito; Chubinskaya, Susan

    2007-06-01

    To assess the safety of epidural administration of Osteogenic Protein-1 (OP-1). To examine if epidural administration of OP-1 or administration into the nucleus pulposus (NP) resulted in ectopic bone formation and/or pain-related behavior. OP-1 has the potential for treatment of degenerative disc disease. However, OP-1's safety, when it is applied into the epidural space or herniated nucleus pulposus, is not well established. Forty rats were divided into 5 groups. Sham group: Left L4 and L5 nerve roots were exposed. NP group: The NP obtained from the tail was relocated onto the exposed nerve roots. NP+OP group: The NP obtained from the tail and injected with 0.2 microg of OP-1 in 1 microL of 5% lactose-buffered solution was placed on the nerve roots. GS group: A gelatin sponge was applied on the nerve roots. GS+OP group: A gelatin sponge soaked with 0.2 microg of OP-1 in 1 microL of 5% lactose-buffered solution was placed onto the nerve roots. Motor function and reflex responses to mechanical noxious stimuli were measured in all rats up to 3 weeks after surgery. Three weeks after surgery, all rats were killed for analysis of ectopic bone formation and magnitude of neural compression. Motor paresis was not observed in any groups. Only rats in the NP group showed evidence of irreversible mechanical hyperalgesia after surgery. There were no differences in the mechanical stimuli response among all groups except the NP group. Macroscopic examination revealed no ectopic bone formation or differences in neural compression among the groups. OP-1 application in the epidural space is safe based on behavioral measures and macroscopic observation on ectopic bone formation at 21 days after surgery.

  5. Corrosion Behavior of Arc Sprayed Nickel-Base Coatings

    NASA Astrophysics Data System (ADS)

    He, Dingyong; Dong, Na; Jiang, Jianmin

    2007-12-01

    In this study, nickel-base cored wires were prepared by using NiCr strip to wrap metal powders of nickel (Ni), chromium (Cr), molybdenum (Mo), and chromium boron (CrB). Nickel-base coatings were prepared by electric arc spraying. Microstructures of Ni-Cr-Mo and Ni-Cr-B coatings were investigated using scanning electron microscopy (SEM), energy-dispersive analysis (EDAX), and x-ray diffraction (XRD) analysis. The coatings have a compact surface and presented a bonding strength higher than 40 MPa. Potentiodynamic polarization measurements and salt-spray test were carried out to determine the corrosion behavior of the coatings. The results showed that Ni-base coatings containing Mo (5%) or B (2-4%) had better antichlorine ion corrosion performance than that of Ni-base coatings without Mo element, and PS45 (Ni-Cr-Ti) coating. The antichlorine ion corrosion coatings could be used for resolving the corrosion protection problem of the equipment and piping contacting sour, alkali, salt liquid in petrochemical engineering applications.

  6. Mechanical Behavior of Spray-Coated Metallic Laminates

    NASA Astrophysics Data System (ADS)

    Vackel, Andrew; Nakamura, Toshio; Sampath, Sanjay

    2016-06-01

    Thermal spray (TS) coatings have been extensively utilized for various surface modifications such as enhancing wear/erosion resistance and thermal protection. In the present study, a new function of TS material is explored by studying its load-carrying capability. Due to the inherent microstructures containing voids and interfaces, it has been presumed TS materials were not suitable to bear loads. However, the recent advances in TS technology to manufacture near fully dense TS coatings have expanded their potential applications. In the current experiments, TS nickel coatings are deposited onto metallic substrates, and their mechanical behaviors are closely examined. Based on the measured data, the estimated elastic modulus of TS Ni is about 130 GPa (35% less than bulk value), and the maximum tensile strength is about 500 MPa (comparable to bulk value). It was found that such a high value is attainable because the coating is deposited onto a substrate, enabling a load-transfer mechanism and preventing coating failure at a much lower stress level. Three distinct deformation stages are identified to describe this behavior. Such a clarification is critical for enabling TS process to restore structural parts as well as to additively manufacture load-bearing components.

  7. Venom-spraying behavior of the scorpion Parabuthus transvaalicus (Arachnida: Buthidae).

    PubMed

    Nisani, Zia; Hayes, William K

    2015-06-01

    Many animals use chemical squirting or spraying behavior as a defensive response. Some members of the scorpion genus Parabuthus (family Buthidae) can spray their venom. We examined the stimulus control and characteristics of venom spraying by Parabuthus transvaalicus to better understand the behavioral context for its use. Venom spraying occurred mostly, but not always, when the metasoma (tail) was contacted (usually grasped by forceps), and was absent during stinging-like thrusts of the metasoma apart from contact. Scorpions were significantly more likely to spray when contact was also accompanied by airborne stimuli. Sprays happened almost instantaneously following grasping by forceps (median=0.23s) as a brief (0.07-0.30s, mean=0.18s), fine stream (<5° arc) that was not directed toward the stimulus source; however, rapid independent movements of the metasoma and/or telson (stinger) often created a more diffuse spray, increasing the possibility of venom contact with the sensitive eyes of potential scorpion predators. Successive venom sprays varied considerably in duration and velocity. Collectively, these results suggest that venom spraying might be useful as an antipredator function and can be modulated based on threat.

  8. Self-extinguishing behavior of kerosene spray fire in a completely enclosed compartment

    NASA Astrophysics Data System (ADS)

    Wang, Changjian; Guo, Jin; Yan, Weigang; Lu, Shouxiang

    2013-10-01

    The self-extinguishing behavior of kerosene spray fire was investigated in a completely enclosed compartment with the size of 3 m × 3 m × 3.4 m. The spray was generated by locating one BETE nozzle at the center of the bottom wall. A series of spray fire videos were obtained by changing BETE nozzle type and injecting pressure. The results show that spray fire undergoes four stages: the growth stage, the quasi-steady stage, the stretch stage and the self-extinguishing stage. Consumption of large quantities of oxygen causes spray fire to first be stretched and then quench. In this process, fire base migrates away from spray region and leads to the emergence of ghosting fire. Ghosting fire promotes the instability of spray fire and large fluctuation of its height, which provides help to its self-extinguishing. With increasing the injecting pressure or the nozzle diameter, the self-extinguishing time decreases. It is found that the self-extinguishing time is approximately in inverse relation with injecting flow rate. Additionally, we also observed the occurrence of two-phase deflagration just after ignition, and it accelerates the spray fire growth and induces a larger fire height than the following quasi-steady spray fire. The deflagration turns stronger with increasing the injecting pressure.

  9. Effect of storage conditions on compaction behavior of two grades of spray-dried lactose.

    PubMed

    Atassi, Faraj; Almaya, Ahmad; Aburub, Aktham

    2008-01-01

    In this work we examine the effect of storage conditions (moisture exposure) on the compression behavior of 2 grades of spray-dried lactose (Pharmatose DCL 11 and Pharmatose DCL 14) under 2 different circumstances. The first was to expose powder samples to moisture, then compress them. The second was to expose precompressed tablets to moisture. We clearly show that the effect of moisture exposure and amorphous content crystallization in spray-dried lactoses on compaction behavior depends on whether this moisture exposure takes place before or after compression. In addition, the impact of storage conditions depends on the grade of spray-dried lactose.

  10. The effect of interlayer adhesion on the mechanical behaviors of macroscopic graphene oxide papers.

    PubMed

    Gao, Yun; Liu, Lu-Qi; Zu, Sheng-Zhen; Peng, Ke; Zhou, Ding; Han, Bao-Hang; Zhang, Zhong

    2011-03-22

    High mechanical performances of macroscopic graphene oxide (GO) papers are attracting great interest owing to their merits of lightweight and multiple functionalities. However, the loading role of individual nanosheets and its effect on the mechanical properties of the macroscopic GO papers are not yet well understood. Herein, we effectively tailored the interlayer adhesions of the GO papers by introducing small molecules, that is, glutaraldehyde (GA) and water molecules, into the gallery regions. With the help of in situ Raman spectroscopy, we compared the varied load-reinforcing roles of nanosheets, and further predicted the Young's moduli of the GO papers. Systematic mechanical tests have proven that the enhancement of the tensile modulus and strength of the GA-treated GO paper arose from the improved load-bearing capability of the nanosheets. On the basis of Raman and macroscopic mechanical tests, the influences of interlayer adhesions on the fracture mechanisms of the strained GO papers were inferred.

  11. Crack Initiation and Growth Behavior of Cold-Sprayed Ni Particles on IN718 Alloy

    NASA Astrophysics Data System (ADS)

    Cavaliere, P.; Silvello, A.

    2017-03-01

    Cold spray processing parameters, governing particle velocity and impact energy, are analyzed in the present paper for pure Ni sprayed on IN718 substrates. Finite element modeling (FEM) was used to calculate the particle impact velocity and temperature as a function of gas temperature and pressure and particle density and dimensions. Experimental evidence underlines the possibility of performing repairing through cold spray thanks to the good level of adhesion achievable by employing optimal combinations of materials and spray processing parameters. In the present paper, the potential repairing of cracked superalloys sheets, by employing cold spray technology, is presented. 30° surface V-notched IN718 panels have been repaired by using pure Ni cold-sprayed powders. The bending behavior of the repaired sheets was analyzed by FEM and mechanical testing in order to compare the properties with those belonging to the unrepaired panels. Simulations and mechanical results showed a reduction in the stress intensity factor, a modification of the crack initiation site and a crack retardation in the repaired structures if compared with the unrepaired ones. The K factor was quantified; the resistance of repaired panels was increased of more than eight times in the case of repairing with Ni cold spray particles. Geometrical and mechanical properties of the coating-substrate interfaces, such as adhesion strength and residual stresses influencing the coatings behavior, were largely analyzed.

  12. The Corrosion Behavior of Cold Sprayed Zinc Coatings on Mild Steel Substrate

    NASA Astrophysics Data System (ADS)

    Chavan, Naveen Manhar; Kiran, B.; Jyothirmayi, A.; Phani, P. Sudharshan; Sundararajan, G.

    2013-04-01

    Zinc and its alloy coatings have been used extensively for the cathodic protection of steel. Zinc coating corrodes in preference to the steel substrate due to its negative corrosion potential. Numerous studies have been conducted on the corrosion behavior of zinc and its alloy coatings deposited using several techniques viz., hot dip galvanizing, electrodeposition, metalizing or thermal spray etc. Cold spray is an emerging low temperature variant of thermal spray family which enables deposition of thick, dense, and pure coatings at a rapid rate with an added advantage of on-site coating of steel structures. In the present study, the corrosion characteristics of cold sprayed zinc coatings have been investigated for the first time. In addition, the influence of heat treatment of zinc coating at a temperature of 150 °C on its corrosion behavior has also been addressed.

  13. Microstructure and wear behavior of quasicrystalline thermal sprayed coatings

    SciTech Connect

    Sordelet, D.J.; Krotz, P.D.; Daniel, R.L. Jr.; Smith, M.F.

    1995-12-31

    An Al-Cu-Fe alloy coating which forms a quasicrystalline phase is a potential candidate for replacing electro-deposited chromium on various components in the Space Shuttle Main Engine. Coatings were deposited by air and vacuum plasma spraying and by high-velocity oxygen-fuel spraying. Finer starting powders tended to lose Al during spraying, which affected the phase equilibrium of the coatings. Coatings which retained the starting powder composition were richer in the desired quasicrystalline phase. Ball-on-disk wear tests between 440 C stainless steel ball and the Al-Cu-Fe coatings were performed. Coefficients of friction ranged from 0.60 to 1.2 for the different coatings.

  14. Microstructure and wear behavior of quasicrystalline thermal sprayed

    SciTech Connect

    Sordelet, D.J.; Krotz, P.D.; Daniel, R.L.; Smith, M.F.

    1994-12-31

    An Al-Cu-Fe alloy coating which forms a quasicrystalline phase is a potential candidate for replacing electro-deposited chromium on various components in the Space Shuttle Main Engine. Coatings were deposited by air and vacuum plasma spraying and by high-velocity oxygen-fuel spraying. Finer starting powders tended to lose Al during spraying, which affected the phase equilibrium of the coatings. Coatings which retained the starting powder composition were richer in the desired quasicrystalline phase. Ball-on-disk wear tests between 440 C stainless steel ball and the Al-Cu-Fe coatings were performed. Coefficients of friction ranged from 0.60 to 1.2 for the different coatings.

  15. Effects of a selective serotonin reuptake inhibitor on urine spraying behavior in cats.

    PubMed

    Pryor, P A; Hart, B L; Cliff, K D; Bain, M J

    2001-12-01

    To determine the effectiveness of a readily available selective serotonin reuptake inhibitor (SSRI), fluoxetine hydrochloride, on reducing problem urine spraying in cats. Randomized placebo-controlled double-blind clinical trial. 17 neutered cats > 1 year old with objectionable urine spraying behavior. Procedure-Owners recorded urine-spraying events for 2 weeks (baseline). Cats that vertically marked a mean of > or = 3 times per week were treated for 8 weeks with fluoxetine or fish-flavored liquid placebo. If urine spraying was not reduced by 70% by weeks 4 through 5, the dosage was increased by 50% for weeks 7 and 8. After discontinuation of treatment at the end of 8 weeks, owners recorded daily urine marks for another 4 weeks. The mean (+/- SE) weekly rate of spraying episodes in treated cats was 8.6 (+/- 2.0) at baseline, decreased significantly by week 2 (1.7 +/- 0.6), and continued to decrease by weeks 7 and 8 (0.4 +/- 0.2). The mean weekly spraying rate of cats receiving placebo was 7.8 (+/- 1.5) at baseline, decreased only slightly during week 1 (5.5 +/- 1.8), and did not decline further. When treatment was discontinued after 8 weeks, the spraying rate of cats that had received treatment varied. The main adverse reaction to the drug was a reduction in food intake, which was observed in 4 of 9 treated cats. Administration of fluoxetine hydrochloride for treatment of urine spraying in cats can be expected to considerably reduce the rate of urine marking. The frequency of spraying before treatment is predictive of the spraying rate when the drug is discontinued.

  16. Macroscopic and Microscopic Investigation of Densification Behavior for Gadolinium-doped Ceria upon Sintering

    NASA Astrophysics Data System (ADS)

    Kosaka, T.; Sato, K.

    2011-10-01

    The densification behaviour of Gadolinium-doped ceria (GDC) upon sintering is investigated from macroscopic and microscopic points of view. The time-resolved length-change measurement with high-resolution dilatometry and positron lifetime spectroscopy are conducted. Positron lifetime spectroscopy reveals the presence of nanovoids at grain boundaries in GDC. Time-dependent length-change measurement reveals that particle rearrangement occurs at the initial stage of sintering. Densifications at the sintering neck and inside the particle grain are discussed.

  17. Elastic and Anelastic Behavior of TBCs Sprayed at High-Deposition Rates

    NASA Astrophysics Data System (ADS)

    Valarezo, A.; Dwivedi, G.; Sampath, S.; Musalek, R.; Matejicek, J.

    2015-01-01

    Coatings sprayed at high-deposition rates often result in stiff, dense, and highly stressed coatings. The high deposition temperature at which the coatings are formed is responsible for these characteristics. In this paper, TBCs were sprayed at high-deposition rates, increasing the tensile quenching stresses beyond the threshold of crack opening during spraying. Dense structures were observed within a pass, in the presence of micro and macro defects specifically horizontal cracks within interpasses and vertical segmentation cracks. Mechanical properties, mainly the elastic and anelastic behavior of TBCs were significantly affected by the strain accommodation and friction occurring within intersplats and interpass interfaces. The strain tolerance obtained in as-sprayed conditions decreased as the microstructure and defects sintered during high-temperature heat cycles. The non-linearity degree decreased while the elastic modulus of the various coatings increased to a maximum value.

  18. Wear Behavior of Thermal Spray Coatings on Rotavator Blades

    NASA Astrophysics Data System (ADS)

    Kang, Amardeep Singh; Grewal, Jasmaninder Singh; Jain, Deepak; Kang, Shivani

    2012-03-01

    A rotavator is a motorized cultivator, popularly used to decrease the total time and human efforts in soil preparation. However, under dynamic loading, rotavator blades are subjected to extreme abrasive wear. The objective of this study was to enhance the working life of the rotavator blade in order to decrease the idle time required to reinstate the blade periodically during cultivation. The objective was carried out by means of thermal spray coatings, where the effect of the coatings on the extent of wear and the wear characteristics of the rotavator blades were examined. Three different detonation gun sprayed coatings, namely WC-Co-Cr, Cr3C2NiCr and Stellite-21 were compared in this study on high tensile steel rotavator blades. The wear rates of Cr3C2NiCr and Stellite-21 coated blades showed significant superiority over the uncoated blade, but not as much as shown by WC-Co-Cr coated blade.

  19. On the role of physiochemical properties on evaporation behavior of DISI biofuel sprays

    NASA Astrophysics Data System (ADS)

    Knorsch, Tobias; Heldmann, Markus; Zigan, Lars; Wensing, Michael; Leipertz, Alfred

    2013-06-01

    Biofuels and alternative fuels are increasingly being blended to conventional gasoline fuel to reduce the overall CO2 emissions. The effect on NOx and soot formation is still unclear as the atomization and evaporation of gasoline with biocomponents differ depending on fuel specific physiochemical properties. This work focuses on describing the biofuel evaporation behavior of gasoline sprays at homogeneous charge (early injection timing) and stratified-charge conditions (late injection timing mode) used in modern direct injection spark ignition engines (DISI). A spray plume of a 6-hole solenoid injector is analyzed in terms of liquid spray propagation, and local droplet sizes studied in an injection chamber. Depending on the operating conditions, different physiochemical properties are found to dominate the atomization and evaporation processes: For low and moderate ambient temperature and pressure, high-boiling point components show a strong influence on the spray droplet size distribution. However, at elevated temperature and pressure, the evaporation behavior changes completely. Due to a high degree of evaporation, the evaporation cooling effect dominates the local droplet sizes. Fuel mixtures owing a larger heat of vaporization show larger droplet sizes—even if these fuels have a lower boiling point. Depending on the local evaporation behavior, the different remaining droplet momentum in the spray controls the air entrainment and the subsequent progress of evaporation and mixing. Overall, it can be stated that the heat of vaporization is a dominating physiochemical property for the droplet evaporation rate at high-level supercharged conditions.

  20. Complete classification of the macroscopic behavior of a heterogeneous network of theta neurons.

    PubMed

    Luke, Tanushree B; Barreto, Ernest; So, Paul

    2013-12-01

    We design and analyze the dynamics of a large network of theta neurons, which are idealized type I neurons. The network is heterogeneous in that it includes both inherently spiking and excitable neurons. The coupling is global, via pulselike synapses of adjustable sharpness. Using recently developed analytical methods, we identify all possible asymptotic states that can be exhibited by a mean field variable that captures the network's macroscopic state. These consist of two equilibrium states that reflect partial synchronization in the network and a limit cycle state in which the degree of network synchronization oscillates in time. Our approach also permits a complete bifurcation analysis, which we carry out with respect to parameters that capture the degree of excitability of the neurons, the heterogeneity in the population, and the coupling strength (which can be excitatory or inhibitory). We find that the network typically tends toward the two macroscopic equilibrium states when the neuron's intrinsic dynamics and the network interactions reinforce one another. In contrast, the limit cycle state, bifurcations, and multistability tend to occur when there is competition among these network features. Finally, we show that our results are exhibited by finite network realizations of reasonable size.

  1. An investigation of the electrical behavior of thermally-sprayed aluminum oxide

    SciTech Connect

    Swindeman, C.J.; Seals, R.D.; White, R.L.; Murray, W.P.; Cooper, M.H.

    1996-09-01

    Electrical properties of plasma-sprayed aluminum oxide coatings were measured at temperatures up to 600 C. High purity (> 99.5 wt% pure Al{sub 2}O{sub 3}) alumina powders were plasma-sprayed on stainless steel substrates over a range of power levels, using two gun configurations designed to attain different spray velocities. Key electrical properties were measured to evaluate the resultant coatings as potential insulating materials for electrostatic chucks (ESCs) being developed for semiconductor manufacturing. Electrical resistivity of all coatings was measured under vacuum upon heating and cooling over a temperature range of 20 to 600 C. Dielectric constants were also measured under the same test conditions. X-ray diffraction was performed to examine phase formation in the coatings. Results show the important of powder composition and careful selection and control of spray conditions for optimizing electrical behavior in plasma-sprayed aluminum oxide, and point to the need for further studies to characterize the relationship between high temperature electrical properties, measured plasma-spray variables, and specific microstructural and compositional coating features.

  2. Behavioral response of Anopheles darlingi to DDT-sprayed house walls in Amazonia.

    PubMed

    Roberts, D R; Alecrim, W D

    1991-01-01

    The behavioral response of Anopheles darlingi females to spraying of house walls with DDT was studied along the Ituxi River in Amazonas, Brazil, using a house sprayed with 2 g DDT per square meter of wall surface and an untreated house serving as a control. It was found that hardly any An. darlingi females entered, exited, or took blood meals inside the treated house after it was sprayed with DDT, and that specimens marked and released inside the house tended to depart immediately. This behavior appears to constitute true repellency rather than contact irritability. Since the typical house in the vicinity of the study site had only two walls, the persistence of malaria in the local area was probably due to home construction practices.

  3. Numerical Study on Plasma Jet and Particle Behavior in Multi-arc Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Bobzin, K.; Öte, M.; Schein, J.; Zimmermann, S.

    2017-06-01

    Plasma jet and particle behavior in conventional single-arc plasma spraying has been subject to intensive numerical research. However, multi-arc plasma spraying is a different case which has yet to be investigated more closely. Numerical models developed to investigate the characteristics of multi-arc plasma spraying (plasma generator, plasma jet, and plasma-particle interaction models) were introduced in previous publications by the authors. The plasma generator and plasma jet models were already validated by comparing calculated plasma temperatures with results of emission spectroscopic computed tomography. In this study, the above-mentioned models were subjected to further validation effort. Calculated particle in-flight characteristics were compared with those determined by means of particle diagnostics and high-speed videography. The results show very good agreement. The main aim of the current publication is to derive conclusions regarding the general characteristics of plasma jet and particle in-flight behavior in multi-arc plasma spraying. For this purpose, a numerical parameter study is conducted in which the validated models are used to allow variations in the process parameters. Results regarding plasma jet/particle in-flight temperatures and velocities are presented. Furthermore, the general characteristics of plasma jet and particle behavior in multi-arc plasma spraying are discussed and explained. This contributes to better understanding of the multi-arc plasma spraying process, in particular regarding the injection behavior of particles into hot regions of the plasma jet. Finally, an example test case showing a possible practical application area of the models is introduced.

  4. Influence of containment spray systems on the source term behavior of VVER-1000-type reactors

    SciTech Connect

    Sdouz, G. )

    1993-01-01

    In Austria a research program to investigate the source term behavior of VVER-type reactors is still going on. The first two generations of VVER-type reactors were designed for 440-MW(electric) power. The next generation with 1000-MW(electric) power is known as the VVER-1000. These reactors have four loops without isolation valves, horizontal steam generators, and hexagonal fuel assemblies. In addition to the first two generations, this type has a containment structure with spray-type steam suppression. The three spray systems work autonomously with a special power supply for each system. The purpose of the containment spray system is to control the pressure within the containment by cooling and condensing steam from the atmosphere and to remove airborne aerosols. To investigate the source term behavior of VVER-type reactors, Austria acquired the Source Term Code Package (STCP) and started the program investigating a TMLB and an S[sub 1]B accident sequence. In the next step, a calculation of the TMLB sequence with working spray systems and emergency core coolant (ECC) recirculation was performed. This paper describes the results of the calculation, the comparison with the calculation without spray, and the implications for the accident management of VVER-1000-type reactors.

  5. Tribological and Oxidative Behavior of Thermally Sprayed NiCrBSi Coatings

    NASA Astrophysics Data System (ADS)

    Garrido, M. A.; Rico, A.; Gómez, M. T.; Cadenas, M.; Fernández-Rico, J. E.; Rodríguez, J.

    2017-01-01

    The behavior of NiCrBSi coatings deposited by three different spraying techniques was studied: flame spray with a subsequent flame treatment (FS + Flame), flame spray with post-laser treatment (FS + Laser) and laser cladding (LC). The coating responses under wear and oxidation conditions were analyzed. Although the microstructure of the coatings deposited by the three different techniques showed similar phases and precipitates, some changes in the size and distribution of these constituents were observed. The pin on disk configuration was used to determine the friction coefficients and wear rates. LC coatings showed the highest wear resistance, with plastic deformation being the main wear mechanism identified for all of the coatings analyzed. Tests under aggressive environments were also performed to determine the oxidation kinetics.

  6. Tribological and Oxidative Behavior of Thermally Sprayed NiCrBSi Coatings

    NASA Astrophysics Data System (ADS)

    Garrido, M. A.; Rico, A.; Gómez, M. T.; Cadenas, M.; Fernández-Rico, J. E.; Rodríguez, J.

    2017-02-01

    The behavior of NiCrBSi coatings deposited by three different spraying techniques was studied: flame spray with a subsequent flame treatment (FS + Flame), flame spray with post-laser treatment (FS + Laser) and laser cladding (LC). The coating responses under wear and oxidation conditions were analyzed. Although the microstructure of the coatings deposited by the three different techniques showed similar phases and precipitates, some changes in the size and distribution of these constituents were observed. The pin on disk configuration was used to determine the friction coefficients and wear rates. LC coatings showed the highest wear resistance, with plastic deformation being the main wear mechanism identified for all of the coatings analyzed. Tests under aggressive environments were also performed to determine the oxidation kinetics.

  7. A robust macroscopic model for normal-shear coupling, asymmetric and anisotropic behaviors of polycrystalline SMAs

    NASA Astrophysics Data System (ADS)

    Bodaghi, M.; Damanpack, A. R.; Liao, W. H.

    2016-07-01

    The aim of this article is to develop a robust macroscopic bi-axial model to capture self-accommodation, martensitic transformation/orientation/reorientation, normal-shear deformation coupling and asymmetric/anisotropic strain generation in polycrystalline shape memory alloys. By considering the volume fraction of martensite and its preferred direction as scalar and directional internal variables, constitutive relations are derived to describe basic mechanisms of accommodation, transformation and orientation/reorientation of martensite variants. A new definition is introduced for maximum recoverable strain, which allows the model to capture the effects of tension-compression asymmetry and transformation anisotropy. Furthermore, the coupling effects between normal and shear deformation modes are considered by merging inelastic strain components together. By introducing a calibration approach, material and kinetic parameters of the model are recast in terms of common quantities that characterize a uniaxial phase kinetic diagram. The solution algorithm of the model is presented based on an elastic-predictor inelastic-corrector return mapping process. In order to explore and demonstrate capabilities of the proposed model, theoretical predictions are first compared with existing experimental results on uniaxial tension, compression, torsion and combined tension-torsion tests. Afterwards, experimental results of uniaxial tension, compression, pure bending and buckling tests on {{NiTi}} rods and tubes are replicated by implementing a finite element method along with the Newton-Raphson and Riks techniques to trace non-linear equilibrium path. A good qualitative and quantitative correlation is observed between numerical and experimental results, which verifies the accuracy of the model and the solution procedure.

  8. Macroscopic and Microstructural Aspects of the Transformation Behavior in a Polycrystalline NiTi Shape Memory Alloy

    NASA Technical Reports Server (NTRS)

    Benafan, Othmane; Noebe, Ronald D.; Padula, Santo A., II; Lerch, Bradley A.; Bigelow, Glen S.; Gaydosh, Darrell J.; Garg, Anita; An, Ke; Vaidyanathan, Raj

    2013-01-01

    The mechanical and microstructural behavior of a polycrystalline Ni(49.9)Ti(50.1) (at.%) shape memory alloy was investigated as a function of temperature around the transformation regime. The bulk macroscopic responses, measured using ex situ tensile deformation and impulse excitation tests, were compared to the microstructural evolution captured using in situ neutron diffraction. The onset stress for inelastic deformation and dynamic Young's modulus were found to decrease with temperature, in the martensite regime, reaching a significant minimum at approximately 80 C followed by an increase in both properties, attributed to the martensite to austenite transformation. The initial decrease in material compliance during heating affected the ease with which martensite reorientation and detwinning could occur, ultimately impacting the stress for inelastic deformation prior to the start of the reverse transformation.

  9. Investigation into macroscopic and microscopic behaviors of wet granular soils using discrete element method and X-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Than, Vinh-Du; Tang, Anh-Minh; Roux, Jean-Noël; Pereira, Jean-Michel; Aimedieu, Patrick; Bornert, Michel

    2017-06-01

    We present an investigation into macroscopic and microscopic behaviors of wet granular soils using the discrete element method (DEM) and the X-ray Computed Tomography (XRCT) observations. The specimens are first prepared in very loose states, with frictional spherical grains in the presence of a small amount of an interstitial liquid. Experimental oedometric tests are carried out with small glass beads, while DEM simulations implement a model of spherical grains joined by menisci. Both in experiments and in simulations, loose configurations with solid fraction as low as 0.30 are prepared under low stress, and undergo a gradual collapse in compression, until the solid fraction of cohesionless bead packs (0.58 to 0.6) is obtained. In the XRCT tests, four 3D tomography images corresponding to different typical stages of the compression curve are used to characterize the microstructure.

  10. Microstructure, microhardness and dry friction behavior of cold-sprayed tin bronze coatings

    NASA Astrophysics Data System (ADS)

    Guo, Xueping; Zhang, Ga; Li, Wen-Ya; Dembinski, Lucas; Gao, Yang; Liao, Hanlin; Coddet, Christian

    2007-12-01

    In this paper, two types of tin bronze coatings (Cu-6 wt.% Sn and Cu-8 wt.% Sn) were prepared by cold spray process. The as-sprayed coatings were subjected to a vacuum heat treatment at 600 °C for 3 h. The coating microstructure, microhardness and tribological performance were characterized. The effects of the tin content and the vacuum heat treatment on the microstructure, microhardness and tribological behavior of the coatings were investigated. It is found that the as-sprayed CuSn6 (As6) and CuSn8 (As8) coatings exhibit practically an identical porosity. Meanwhile, As8 presents a higher microhardness than As6. In addition, the increase of the tin content in the powder feedstock leads to a lower wear rate. After a heat treatment, coating porosities are significantly reduced. However, the coating hardness is significantly decreased and the coating presents a much decreased wear resistance. For the as-sprayed coatings, such factors as ploughing and particle delamination could determine the sliding process. The heat treatment results in a distinct modification of the tribological behavior. For the annealed coatings, the adhesion, between the coating and the counterpart, could play a dominant role in the sliding process.

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

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

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

  12. A hierarchical approach to accurate predictions of macroscopic thermodynamic behavior from quantum mechanics and molecular simulations

    NASA Astrophysics Data System (ADS)

    Garrison, Stephen L.

    2005-07-01

    The combination of molecular simulations and potentials obtained from quantum chemistry is shown to be able to provide reasonably accurate thermodynamic property predictions. Gibbs ensemble Monte Carlo simulations are used to understand the effects of small perturbations to various regions of the model Lennard-Jones 12-6 potential. However, when the phase behavior and second virial coefficient are scaled by the critical properties calculated for each potential, the results obey a corresponding states relation suggesting a non-uniqueness problem for interaction potentials fit to experimental phase behavior. Several variations of a procedure collectively referred to as quantum mechanical Hybrid Methods for Interaction Energies (HM-IE) are developed and used to accurately estimate interaction energies from CCSD(T) calculations with a large basis set in a computationally efficient manner for the neon-neon, acetylene-acetylene, and nitrogen-benzene systems. Using these results and methods, an ab initio, pairwise-additive, site-site potential for acetylene is determined and then improved using results from molecular simulations using this initial potential. The initial simulation results also indicate that a limited range of energies important for accurate phase behavior predictions. Second virial coefficients calculated from the improved potential indicate that one set of experimental data in the literature is likely erroneous. This prescription is then applied to methanethiol. Difficulties in modeling the effects of the lone pair electrons suggest that charges on the lone pair sites negatively impact the ability of the intermolecular potential to describe certain orientations, but that the lone pair sites may be necessary to reasonably duplicate the interaction energies for several orientations. Two possible methods for incorporating the effects of three-body interactions into simulations within the pairwise-additivity formulation are also developed. A low density

  13. Macroscopic investigation of water volume effects on interfacial dynamic behaviors between clathrate hydrate and water.

    PubMed

    Cha, Minjun; Couzis, Alexander; Lee, Jae W

    2013-05-14

    This study investigated the effects of the water volume on the interfacial dynamics between cyclopentane (CP) hydrate and water droplet in a CP/n-decane oil mixture. The adhesion force between CP hydrate and various water droplets was determined using the z-directional microbalance. Through repetition of precise measurements over several cycles from contact to detachment, we observed abnormal wetting behaviors in the capillary bridge during the retraction process when the water drop volume is larger than 100 μL. With the increase in water droplet volumes, the contact force between CP hydrate and water also increases up to 300 μL. However, there is a dramatic reduction of increasing rate in the contact forces over 300 μL of water droplet. With the addition of the surfactants of sodium dodecyl sulfate (SDS) and dodecyltrimethylammonium bromide (DTAB) to the water droplet, the contact force between CP hydrate and solution droplet exhibits a lower value and a transition volume of the contact force comes with a smaller solution volume of 200 μL. The water volume effects on the liquid wetting of the probe and the size of capillary bridges provide important insight into hydrate growth and aggregation/agglomeration in the presence of free water phase inside gas/oil pipelines.

  14. Ergodicity reflected in macroscopic and microscopic field-dependent behavior of BNT-based relaxors

    SciTech Connect

    Dittmer, Robert; Jo, Wook Rödel, Jürgen; Gobeljic, Danka; Shvartsman, Vladimir V.; Lupascu, Doru C.; Jones, Jacob L.

    2014-02-28

    The effect of heterovalent B-site doping on ergodicity of relaxor ferroelectrics is studied using (1 − y)(0.81Bi{sub 1/2}Na{sub 1/2}TiO{sub 3}-0.19Bi{sub 1/2}K{sub 1/2}TiO{sub 3})-yBiZn{sub 1/2}Ti{sub 1/2}O{sub 3} (BNT-BKT-BZT) with y = (0.02;0.03;0.04) as a model system. Both the large- and small-signal parameters are studied as a function of electric field. The crystal structure is assessed by means of neutron diffraction in the initial state and after exposure to a high electric field. In order to measure ferroelastic domain textures, diffraction patterns of the poled samples are collected as a function of sample rotation angle. Piezoresponse force microscopy (PFM) is employed to probe the microstructure for polar regions at a nanoscopic scale. For low electric fields E < 2 kV·mm{sup −1}, large- and small-signal constitutive behavior do not change with composition. At high electric fields, however, drastic differences are observed due to a field-induced phase transition into a long-range ordered state. It is hypothesized that increasing BZT content decreases the degree of non-ergodicity; thus, the formation of long-range order is impeded. It is suggested that frozen and dynamic polar nano regions exist to a different degree, depending on the BZT content. This image is supported by PFM measurements. Moreover, PFM measurements suggest that the relaxation mechanism after removal of the bias field is influenced by surface charges.

  15. Ergodicity reflected in macroscopic and microscopic field-dependent behavior of BNT-based relaxors

    NASA Astrophysics Data System (ADS)

    Dittmer, Robert; Gobeljic, Danka; Jo, Wook; Shvartsman, Vladimir V.; Lupascu, Doru C.; Jones, Jacob L.; Rödel, Jürgen

    2014-02-01

    The effect of heterovalent B-site doping on ergodicity of relaxor ferroelectrics is studied using (1 - y)(0.81Bi1/2Na1/2TiO3-0.19Bi1/2K1/2TiO3)-yBiZn1/2Ti1/2O3 (BNT-BKT-BZT) with y = {0.02;0.03;0.04} as a model system. Both the large- and small-signal parameters are studied as a function of electric field. The crystal structure is assessed by means of neutron diffraction in the initial state and after exposure to a high electric field. In order to measure ferroelastic domain textures, diffraction patterns of the poled samples are collected as a function of sample rotation angle. Piezoresponse force microscopy (PFM) is employed to probe the microstructure for polar regions at a nanoscopic scale. For low electric fields E < 2 kV.mm-1, large- and small-signal constitutive behavior do not change with composition. At high electric fields, however, drastic differences are observed due to a field-induced phase transition into a long-range ordered state. It is hypothesized that increasing BZT content decreases the degree of non-ergodicity; thus, the formation of long-range order is impeded. It is suggested that frozen and dynamic polar nano regions exist to a different degree, depending on the BZT content. This image is supported by PFM measurements. Moreover, PFM measurements suggest that the relaxation mechanism after removal of the bias field is influenced by surface charges.

  16. Understanding the microscopic deformation mechanism and macroscopic mechanical behavior of nanocrystalline Ni by the long-term stress relaxation test

    NASA Astrophysics Data System (ADS)

    Shen, Xixun; Zhang, Congcong; Zeng, Tao; Cheng, Danhong; Lian, Jianshe

    2014-05-01

    The long-term stress relaxation tests with a relaxation time of about 7 h are performed on the bulk dense nanocrystalline Ni (with a mean grain size of 27 nm) pre-deformed at strain rate from 4.17 s-1- 4.17 × 10-6 s-1, where a phenomenon that the initial relaxation behavior of nc Ni depends on itself deformation history. That is, the nc Nis pre-deformed at higher strain rate (not less than 4.17 × 10-3 s-1) exhibit a three-staged relaxation process from the initial near linear rapidly stress delayed (LRSD) stage and the subsequent lumber nonlinear stress delayed (LNSD) one and the final near linear slowly stress delayed (LSSD) one while only the later two stages are observed for the nc Nis pre-deformed at low strain rate. The three-stage relaxation behavior is attributed to the transition from the initial dislocation-dominated plasticity to the mixture of dislocation motion and diffusion-based GB activity and finally to the entire diffusion-based GB activity including GB sliding or grain rotation in the rate-controlling deformation mechanism, which was illuminated by the attained three-staged strain rate sensitivity and activation volume and the exhaustion of mobile density of deformed nc Ni in the first two stages of relaxation. Such rate-controlling deformation mechanism well interpreted the macroscopic tensile mechanical behavior of nc Ni and simultaneously an optimizing strategy in improving the ductility of nc Ni is also mentioned.

  17. A Study on the Tribological Behavior of Vanadium-Doped Arc Sprayed Coatings

    NASA Astrophysics Data System (ADS)

    Tillmann, Wolfgang; Hagen, Leif; Kokalj, David; Paulus, Michael; Tolan, Metin

    2017-02-01

    The formation of thin reactive films in sliding contacts under elevated temperature provides enhanced tribological properties since the formation of Magnéli phases leads to the ability of self-lubricating behavior. This phenomenon was studied for vanadium-doped coating systems which were produced using CVD and PVD technology. Vanadium-containing arc sprayed coatings were not widely examined so far. The aim of this study was to characterize Fe-V coatings deposited by the Twin Wire Arc Spraying process with respect to their oxidation behavior at elevated temperatures and to correlate the formation of oxides to the tribological properties. Dry sliding experiments were performed in the temperature range between 25 and 750 °C. The Fe-V coating possesses a reduced coefficient of friction and wear coefficient ( k) at 650 and 750 °C, which were significant lower when compared to conventional Fe-based coatings. The evolution of oxide phases was identified in situ by x-ray diffraction for the investigated temperature range. Further oxidation of (pre-oxidized) arc sprayed Fe-V coatings, as verified by differential thermal analysis and thermo-gravimetric analysis, starts at about 500 °C.

  18. A Study on the Tribological Behavior of Vanadium-Doped Arc Sprayed Coatings

    NASA Astrophysics Data System (ADS)

    Tillmann, Wolfgang; Hagen, Leif; Kokalj, David; Paulus, Michael; Tolan, Metin

    2017-01-01

    The formation of thin reactive films in sliding contacts under elevated temperature provides enhanced tribological properties since the formation of Magnéli phases leads to the ability of self-lubricating behavior. This phenomenon was studied for vanadium-doped coating systems which were produced using CVD and PVD technology. Vanadium-containing arc sprayed coatings were not widely examined so far. The aim of this study was to characterize Fe-V coatings deposited by the Twin Wire Arc Spraying process with respect to their oxidation behavior at elevated temperatures and to correlate the formation of oxides to the tribological properties. Dry sliding experiments were performed in the temperature range between 25 and 750 °C. The Fe-V coating possesses a reduced coefficient of friction and wear coefficient (k) at 650 and 750 °C, which were significant lower when compared to conventional Fe-based coatings. The evolution of oxide phases was identified in situ by x-ray diffraction for the investigated temperature range. Further oxidation of (pre-oxidized) arc sprayed Fe-V coatings, as verified by differential thermal analysis and thermo-gravimetric analysis, starts at about 500 °C.

  19. Impact of the irregular microgeometry of polyurethane foam on the macroscopic acoustic behavior predicted by a unit-cell model.

    PubMed

    Doutres, O; Ouisse, M; Atalla, N; Ichchou, M

    2014-10-01

    This paper deals with the prediction of the macroscopic sound absorption behavior of highly porous polyurethane foams using two unit-cell microstructure-based models recently developed by Doutres, Atalla, and Dong [J. Appl. Phys. 110, 064901 (2011); J. Appl. Phys. 113, 054901 (2013)]. In these models, the porous material is idealized as a packing of a tetrakaidecahedra unit-cell representative of the disordered network that constitutes the porous frame. The non-acoustic parameters involved in the classical Johnson-Champoux-Allard model (i.e., porosity, airflow resistivity, tortuosity, etc.) are derived from characteristic properties of the unit-cell and semi-empirical relationships. A global sensitivity analysis is performed on these two models in order to investigate how the variability associated with the measured unit-cell characteristics affects the models outputs. This allows identification of the possible limitations of a unit-cell micro-macro approach due to microstructure irregularity. The sensitivity analysis mainly shows that for moderately and highly reticulated polyurethane foams, the strut length parameter is the key parameter since it greatly impacts three important non-acoustic parameters and causes large uncertainty on the sound absorption coefficient even if its measurement variability is moderate. For foams with a slight inhomogeneity and anisotropy, a micro-macro model associated to cell size measurements should be preferred.

  20. A comparative study of tribological behavior of plasma and D-gun sprayed coatings under different wear modes

    NASA Astrophysics Data System (ADS)

    Sundararajan, G.; Prasad, K. U. M.; Rao, D. S.; Joshi, S. V.

    1998-06-01

    In recent years, thermal sprayed protective coatings have gained widespread acceptance for a variety of industrial applications. A vast majority of these applications involve the use of thermal sprayed coatings to combat wear. While plasma spraying is the most versatile variant of all the thermal spray processes, the detonation gun (D-gun) coatings have been a novelty until recently because of their proprietary nature. The present study is aimed at comparing the tribological behavior of coatings deposited using the two above techniques by focusing on some popular coating materials that are widely adopted for wear resistant applications, namely, WC-12% Co, A12O3, and Cr3C2-MCr. To enable a comprehensive comparison of the above indicated thermal spray techniques as well as coating materials, the deposited coatings were extensively characterized employing microstructural evaluation, microhardness measurements, and XRD analysis for phase constitution. The behavior of these coatings under different wear modes was also evaluated by determining their tribological performance when subjected to solid particle erosion tests, rubber wheel sand abrasion tests, and pin-on-disk sliding wear tests. The results from the above tests are discussed here. It is evident that the D-gun sprayed coatings consistently exhibit denser microstructures and higher hardness values than their plasma sprayed counterparts. The D-gun coatings are also found to unfailingly exhibit superior tribological performance superior to the corresponding plasma sprayed coatings in all wear tests. Among all the coating materials studied, D-gun sprayed WC-12%Co, in general, yields the best performance under different modes of wear, whereas plasma sprayed Al2O3 shows least wear resistance to every wear mode.

  1. Microstructural Characteristics and Oxidation Behavior of Low-Pressure Cold-Sprayed CoNiCrAlY Coatings

    NASA Astrophysics Data System (ADS)

    Zhang, Lin-wei; Lu, Lei; Wang, Lu; Ning, Xian-jin; Wang, Quan-sheng; Wang, Ri-xin

    2017-09-01

    CoNiCrAlY coatings were deposited by low-pressure cold spraying and subsequently heat-treated at 1050 °C for 4 h in a vacuum environment. The microstructural characteristics and oxidation behavior of CoNiCrAlY coatings were investigated. The as-sprayed coating exhibited low porosity and oxygen content. The high plastic deformation of the sprayed particles led to significant refinement of γ-matrix and dissolution of β-(Ni,Co)Al phase in the as-sprayed coating. After heat treatment, the single phase (γ) in the as-sprayed coating was converted into a γ/β microstructure, and a continuous single α-Al2O3 scale was formed on the coating surface. Vacuum heat treatment can postpone the formation of spinel oxides within 100 h. After being oxidized at 1050 °C for 400 h, the heat-treated coating exhibited better oxidation resistance than the as-sprayed coating. The reduced growth rate of the oxide scale and the suppression of the formation of spinel oxides can be attributed to the vacuum heat treatment, as well as the intrinsic microstructure of the cold-sprayed coating. Finally, the effects of the microstructural changes induced during the cold spraying process on the growth of the thermally grown oxide and the oxidation mechanisms of the CoNiCrAlY coatings were discussed.

  2. Microstructural Characteristics and Oxidation Behavior of Low-Pressure Cold-Sprayed CoNiCrAlY Coatings

    NASA Astrophysics Data System (ADS)

    Zhang, Lin-wei; Lu, Lei; Wang, Lu; Ning, Xian-jin; Wang, Quan-sheng; Wang, Ri-xin

    2017-10-01

    CoNiCrAlY coatings were deposited by low-pressure cold spraying and subsequently heat-treated at 1050 °C for 4 h in a vacuum environment. The microstructural characteristics and oxidation behavior of CoNiCrAlY coatings were investigated. The as-sprayed coating exhibited low porosity and oxygen content. The high plastic deformation of the sprayed particles led to significant refinement of γ-matrix and dissolution of β-(Ni,Co)Al phase in the as-sprayed coating. After heat treatment, the single phase (γ) in the as-sprayed coating was converted into a γ/β microstructure, and a continuous single α-Al2O3 scale was formed on the coating surface. Vacuum heat treatment can postpone the formation of spinel oxides within 100 h. After being oxidized at 1050 °C for 400 h, the heat-treated coating exhibited better oxidation resistance than the as-sprayed coating. The reduced growth rate of the oxide scale and the suppression of the formation of spinel oxides can be attributed to the vacuum heat treatment, as well as the intrinsic microstructure of the cold-sprayed coating. Finally, the effects of the microstructural changes induced during the cold spraying process on the growth of the thermally grown oxide and the oxidation mechanisms of the CoNiCrAlY coatings were discussed.

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

    PubMed

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

    2017-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2017-08-01

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

  5. Mechanical and Tribological Behavior of Ni(Al)-Reinforced Nanocomposite Plasma Spray Coatings

    NASA Astrophysics Data System (ADS)

    Movahedi, B.

    2014-02-01

    The mechanical and tribological behavior and microstructural evolutions of the Ni(Al)-reinforced nanocomposite plasma spray coatings were studied. At first, the feedstock Ni(Al)-15 wt.% (Al2O3-13% TiO2) nanocomposite powders were prepared using low-energy mechanical milling of the pure Ni and Al powders as well as Al2O3-13% TiO2 nanoparticle mixtures. The characteristics of the powder particles and the prepared coatings depending on their microstructures were examined in detail. The results showed that the feedstock powders after milling contained only α-Ni solid solution with no trace of the intermetallic phase. However, under the air plasma spraying conditions, the NiAl intermetallic phase in the α-Ni solid solution matrix appeared. The lack of nickel aluminide formation during low-energy ball milling is beneficial hence, the exothermic reaction can occur between Ni and Al during plasma spraying, improving the adhesive strength of the nanocomposite coatings. The results also indicated that the microhardness of the α-Ni phase was 3.91 ± 0.23 GPa and the NiAl intermetallic phase had a mean microhardness of 5.69 ± 0.12 GPa. The high microhardness of the nanocomposite coatings must be due to the presence of the reinforcing nanoparticles. Due to the improvement in mechanical properties, the Ni(Al) nanocomposite coatings showed significant modifications in wear resistance with low frictional coefficient.

  6. Slurry Erosion and Corrosion Behavior of Some Engineering Polymers Applied by Low-Pressure Flame Spray

    NASA Astrophysics Data System (ADS)

    Lima, Carlos Roberto Camello; Mojena, Miguel Angel Reyes; Rovere, Carlos Alberto Della; de Souza, Natalia Ferraresso Cardoso; Fals, Hipolito Domingo Carvajal

    2016-11-01

    The erosive wear and corrosion resistance of three types of flame spray-deposited polymer coatings was analyzed. The erosive wear test was performed in slurry pot tester with rotational movement using distilled water and mix quartz particles (300 g/l). Two impact angles of the particles were used, reaching 4.15 m/s average impact velocity. Corrosion resistance of the polymer coatings and degradation behavior were investigated by electrochemical impedance spectroscopy in a solution of 0.5 M sodium chloride at room temperature for a total immersion time of 1 year. The interpretation of the results was made according to the Bode plot. It is proven a better slurry erosion wear performance for PEEK and PA12 coatings when the particles impact at 90° angle. For impact angle of 30°, there is no significant difference in the erosion performance of PEEK, PEI, and PA12 coatings. No major changes occurred in the impedance module for PA12 and PEEK samples, indicating that these coatings can protect the steel substrate for extended periods of time. The lower PEI performance is believed to be related to the improper choice of spraying parameters, as the spray conditions were kept constant for the three feedstock materials.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2017-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2017-06-01

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

  10. Achieving large macroscopic compressive plastic deformation and work-hardening-like behavior in a monolithic bulk metallic glass by tailoring stress distribution

    NASA Astrophysics Data System (ADS)

    Chen, L. Y.; Ge, Q.; Qu, S.; Jiang, Q. K.; Nie, X. P.; Jiang, J. Z.

    2008-05-01

    The limited plastic deformation and lack of work hardening seriously restrict the applications of bulk metallic glasses (BMGs). Here, large macroscopic compressive plastic deformation (over 15%) and work-hardening-like behavior were achieved in a monolithic BMG through tailoring loading stress distribution experimentally. Numerical analysis was also carried out to investigate the stress distribution under the same mechanical condition. It is shown that loading induced stress gradient is responsible for the achievement mentioned above.

  11. Arc spraying in China

    NASA Astrophysics Data System (ADS)

    Liu, Xianjun

    2001-03-01

    Although are spraying is not a new technique, recent development of arc spraying device systems, spray wires, research on the coating mechanism, and the dynamic behavior of spraying make it a most active thermal spray process. In China, the arc spraying technique is the most efficient way for long life corrosion protection of steel structures. In addition, the arc spraying process is widely used for renovation and surface modification of machine components, mold making for plastic products, high-temperature corrosion resistance for waterwalls of boilers, antisliding coatings, self-lubricating coatings, etc.

  12. Effect of Aging Treatments on the Mechanical and Corrosive Behaviors of Spray-Formed 7075 Alloy

    NASA Astrophysics Data System (ADS)

    Su, Rui-ming; Qu, Ying-dong; Li, Rong-de

    2014-11-01

    Mechanical properties, microstructure, exfoliation corrosion (EXCO), and intergranular corrosion (IGC) behaviors of the spray-formed 7075 aluminum alloy after T6, T73, retrogression (R), and re-aging (RRA) treatment, respectively, were studied by using tensile tester, transmission electron microscope, and scanning electron microscope. The results show that the T6 process can increase the ultimate tensile strength (UTS) up to 760 MPa, while it decreases the elongation, the EXCO, and the IGC resistance of the alloy. The T73 process can improve elongation, the EXCO, and the IGC resistance of the alloy. The corrosion resistance of the alloy can also be improved by R and RRA processes with retrogression times increase. The tiny precipitated phases distributed homogeneously in the matrix can increase the UTS. The close-connected discrete grain boundary phases (GBP) and the narrow precipitate free zones (PFZ) will lower the elongation, the EXCO, and the IGC resistance of the alloy. Contrarily, the discrete GBP and wide PFZ can improve the elongation, the EXCO, and the IGC resistance of the alloy. The EXCO and the IGC behaviors for the spray-formed 7075 alloy after different aging treatments have been established according to the standards of ASTM G34-2001 (2007) and ASTM G110-1992 (2009).

  13. Colonization of Bacteria on the Surfaces of Cold-Sprayed Copper Coatings Alters Their Electrochemical Behaviors

    NASA Astrophysics Data System (ADS)

    Suo, Xinkun; Abdoli, Leila; Liu, Yi; Xia, Peng; Yang, Guanjun; Li, Hua

    2017-04-01

    Copper coatings were fabricated on stainless steel plates by cold spraying. Attachment and colonization of Bacillus sp. on their surfaces in artificial seawater were characterized, and their effects on anticorrosion performances of the coatings were examined. Attached bacteria were observed using field emission scanning electron microscopy. Electrochemical behaviors including potentiodynamic polarization and electrochemical impedance spectroscopy with/without bacterial attachment were evaluated using commercial electrochemical analysis station Modulab. Results show that Bacillus sp. opt to settle on low-lying spots of the coating surfaces in early stage, followed by recruitment and attachment of extracellular polymeric substances (EPS) secreted through metabolism of Bacillus sp. The bacteria survive with the protection of EPS. An attachment model is proposed to illustrate the bacterial behaviors on the surfaces of the coatings. Electrochemical data show that current density under Bacillus sp. environment decreases compared to that without the bacteria. Charge-transfer resistance increases markedly in bacteria-containing seawater, suggesting that corrosion resistance increases and corrosion rate decreases. The influencing mechanism of bacteria settlement on corrosion resistance of the cold-sprayed copper coatings was discussed and elucidated.

  14. Colonization of Bacteria on the Surfaces of Cold-Sprayed Copper Coatings Alters Their Electrochemical Behaviors

    NASA Astrophysics Data System (ADS)

    Suo, Xinkun; Abdoli, Leila; Liu, Yi; Xia, Peng; Yang, Guanjun; Li, Hua

    2017-02-01

    Copper coatings were fabricated on stainless steel plates by cold spraying. Attachment and colonization of Bacillus sp. on their surfaces in artificial seawater were characterized, and their effects on anticorrosion performances of the coatings were examined. Attached bacteria were observed using field emission scanning electron microscopy. Electrochemical behaviors including potentiodynamic polarization and electrochemical impedance spectroscopy with/without bacterial attachment were evaluated using commercial electrochemical analysis station Modulab. Results show that Bacillus sp. opt to settle on low-lying spots of the coating surfaces in early stage, followed by recruitment and attachment of extracellular polymeric substances (EPS) secreted through metabolism of Bacillus sp. The bacteria survive with the protection of EPS. An attachment model is proposed to illustrate the bacterial behaviors on the surfaces of the coatings. Electrochemical data show that current density under Bacillus sp. environment decreases compared to that without the bacteria. Charge-transfer resistance increases markedly in bacteria-containing seawater, suggesting that corrosion resistance increases and corrosion rate decreases. The influencing mechanism of bacteria settlement on corrosion resistance of the cold-sprayed copper coatings was discussed and elucidated.

  15. Hot corrosion behavior of the spray-formed nickel-based superalloy

    NASA Astrophysics Data System (ADS)

    Xia, Min; Gu, Tian-Fu; Jia, Chong-Lin; Ge, Chang-Chun

    2016-12-01

    An investigation of low temperature hot corrosion is carried out on a spray-formed nickel-based superalloy FGH100 pre-coated with Na2SO4-NaCl at 700 °C for 100 h. Mass gain measurement, x-ray diffraction, scanning electron microscopy, and energy dispersive x-ray spectroscopy are used to study the corrosion behavior. Results reveal that corrosion behavior follows a sequence, that is, first rapidly proceeding, then gradually slowing down, and finally forming an outer layer composed of different types of oxides and an inner layer mainly comprised of sulfides. In-depth analysis reveals that the hot corrosion of FGH100 is a combined effect of oxidation-sulfidation and transfer of oxides.

  16. Corrosion potential behavior in high temperature water of noble metal-doped alloys coatings deposited by underwater thermal spraying

    SciTech Connect

    Kim, Y.J.; Andresen, P.L.; Gray, D.M.; Lau, Y.C.; Offer, H.P.

    1995-12-31

    The electrochemical corrosion potential of 304 stainless steel coated under water by hyper-velocity oxy-fuel and plasma spray techniques using noble metal doped powders was measured to evaluate the catalytic behavior in high temperature water under various water chemistry conditions. Thermal spray coatings of noble metal doped powders exhibited catalytic behavior for the recombination of oxygen and hydrogen in high temperature water which causes the corrosion potential to decrease well below a critical value of {minus}230 mV{sub she} for the intergranular stress corrosion cracking protection in water. This was observed in water containing various amounts of oxygen and hydrogen peroxide when stoichiometric excess hydrogen was present.

  17. Corrosion Behavior of Detonation Gun Sprayed Fe-Al Type Intermetallic Coating.

    PubMed

    Senderowski, Cezary; Chodala, Michal; Bojar, Zbigniew

    2015-03-13

    The detonation gun sprayed Fe-Al type coatings as an alternative for austenitic valve steel, were investigated using two different methods of testing corrosion resistance. High temperature, 10-hour isothermal oxidation experiments at 550, 750, 950 and 1100 °C show differences in the oxidation behavior of Fe-Al type coatings under air atmosphere. The oxide layer ensures satisfying oxidation resistance, even at 950 and 1100 °C. Hematite, α-Al₂O₃ and metastable alumina phases were noticed on the coatings top surface, which preserves its initial thickness providing protection to the underlying substrate. In general, only negligible changes of the phase composition of the coatings were noticed with simultaneous strengthening controlled in the micro-hardness measurements, even after 10-hours of heating at 1100 °C. On the other hand, the electrochemical corrosion tests, which were carried out in 200 ppm Cl(-) (NaCl) and pH ~4 (H₂SO₄) solution to simulate the acid-rain environment, reveal higher values of the breakdown potential for D-gun sprayed Fe-Al type coatings than the ones for the bulk Fe-Al type alloy and Cr21Mn9Ni4 austenitic valve steel. This enables these materials to be used in structural and multifunctional applications in aggressive environments, including acidic ones.

  18. Corrosion Behavior of Detonation Gun Sprayed Fe-Al Type Intermetallic Coating

    PubMed Central

    Senderowski, Cezary; Chodala, Michal; Bojar, Zbigniew

    2015-01-01

    The detonation gun sprayed Fe-Al type coatings as an alternative for austenitic valve steel, were investigated using two different methods of testing corrosion resistance. High temperature, 10-hour isothermal oxidation experiments at 550, 750, 950 and 1100 °C show differences in the oxidation behavior of Fe-Al type coatings under air atmosphere. The oxide layer ensures satisfying oxidation resistance, even at 950 and 1100 °C. Hematite, α-Al2O3 and metastable alumina phases were noticed on the coatings top surface, which preserves its initial thickness providing protection to the underlying substrate. In general, only negligible changes of the phase composition of the coatings were noticed with simultaneous strengthening controlled in the micro-hardness measurements, even after 10-hours of heating at 1100 °C. On the other hand, the electrochemical corrosion tests, which were carried out in 200 ppm Cl− (NaCl) and pH ~4 (H2SO4) solution to simulate the acid-rain environment, reveal higher values of the breakdown potential for D-gun sprayed Fe-Al type coatings than the ones for the bulk Fe-Al type alloy and Cr21Mn9Ni4 austenitic valve steel. This enables these materials to be used in structural and multifunctional applications in aggressive environments, including acidic ones. PMID:28787991

  19. The behavior of high-purity, low-density air plasma sprayed thermal barrier coatings

    SciTech Connect

    Helminiak, Yanar NM

    2009-12-01

    Research on the behavior of high-purity, low-density (85%) air plasma sprayed (APS) thermal barrier coatings (TBC) with NiCoCrAlY bond coats deposited by argon-shrouded plasma spraying is described. The microstructure of the APS topcoats is one variable in this study intended to maximize the coating thicknesses that can be applied without spallation and to minimize the thermal conduction through the YSZ layer. The specimens were evaluated using cyclic oxidation tests and important properties of the TBCs, such as resistance to sintering and phase transformation, were determined. The high purity resulted in top coats which are highly resistant to sintering and transformation from the metastable tetragonal phase to the equilibrium mixture of monoclinic and cubic phases. The porous topcoat microstructure also resulted in significant durability during thermal cycling. The actual failure mechanisms of the APS coatings were found to depend on topcoat thickness, CTE of the superalloy substrate and the nature of the thermal exposure.

  20. The Breakup Mechanism and the Spray Pulsation Behavior of a Three-Stream Atomizer

    NASA Astrophysics Data System (ADS)

    Ng, Chin; Dord, Anne; Aliseda, Alberto

    2011-11-01

    In many processes of industrial importance, such as gasification, the liquid to gas mass ratio injected at the atomizer exceeds the limit of conventional two-fluid coaxial atomizers. To maximize the shear rate between the atomization gas and the liquid while maintaining a large contact area, a secondary gas stream is added at the centerline of the spray, interior to the liquid flow, which is annular in this configuration. This cylindrical gas jet has low momentum and does not contribute to the breakup process, which is still dominated by the high shear between the concentric annular liquid flow and the high momentum gas stream. The presence of two independently controlled gas streams leads to the appearance of a hydrodynamic instability that manifests itself in pulsating liquid flow rates and droplet sizes. We study the dependency of the atomization process on the relative flow rates of the three streams. We measure the size distribution, droplet number density and total liquid volumetric flow rate as a function of time, for realistic Weber and Ohnesorge numbers. Analysis of the temporal evolution of these physical variables reveals the dominant frequency of the instability and its effect on the breakup and dispersion of droplets in the spray. We present flow visualization and Phase Doppler Particle Analyzer results that provide insight into the behavior of this complex coaxial shear flow.

  1. Isothermal Oxidation Behavior of Supersonic Atmospheric Plasma-Sprayed Thermal Barrier Coating System

    NASA Astrophysics Data System (ADS)

    Bai, Yu; Ding, Chunhua; Li, Hongqiang; Han, Zhihai; Ding, Bingjun; Wang, Tiejun; Yu, Lie

    2013-10-01

    In this work, Y2O3 stabilized zirconia-based thermal barrier coatings (TBCs) were deposited by conventional atmospheric plasma spraying (APS) and high efficiency supersonic atmospheric plasma spraying (SAPS), respectively. The effect of Al2O3 layer stability on the isothermal growth behavior of thermally grown oxides (TGOs) was studied. The results revealed that the Al2O3 layer experienced a three-stage change process, i.e., (1) instantaneous growth stage, (2) steady-state growth stage, and (3) depletion stage. The thickness of Al2O3 scale was proved to be an important factor for the growth rate of TGOs. The SAPS-TBCs exhibited a higher Al2O3 stability and better oxidation resistance as compared with the APS-TBCs. Additionally, it was found that inner oxides, especially nucleated on the top of the crest, continually grew and swallowed the previously formed Al2O3 layer, leading to the granulation and disappearance of continuous Al2O3 scale, which was finally replaced by the mixed oxides and spinel.

  2. Water spray-induced grooming is negatively correlated with depressive behavior in the forced swimming test in rats.

    PubMed

    Shiota, Noboru; Narikiyo, Kimiya; Masuda, Akira; Aou, Shuji

    2016-05-01

    Rodents show grooming, a typical self-care behavior, under stress and non-stress conditions. Previous studies revealed that grooming under stress conditions such as the open-field test (OFT) or the elevated plus-maze test (EPM) is associated with anxiety, but the roles of grooming under non-stress conditions are not well understood. Here, we examined spray-induced grooming as a model of grooming under a non-stress condition to investigate the relationship between this grooming and depression-like behavior in the forced swim test (FST) and tail suspension test, and we compared spray-induced grooming with OFT- and EPM-induced grooming. The main finding was that the duration of spray-induced grooming, but not that of OFT/EPM-induced grooming, was negatively correlated with the duration of immobility in the FST, an index of depression-like behavior. The results suggest that spray-induced grooming is functionally different from the grooming in the OFT and EPM and is related to reduction of depressive behavior.

  3. Behavior of Plasma-Sprayed Hydroxyapatite Coatings onto Carbon/carbon Composites in Simulated Body Fluid

    NASA Astrophysics Data System (ADS)

    Sui, Jin-Ling; Bo, Wu; Hai, Zhou; Cao, Ning; Li, Mu-Sen

    Two types of hydroxyapatite (HA) coatings onto carbon/carbon composite (C/C composites) substrates, deposited by plasma spraying technique, were immersed in a simulated body fluid (SBF) in order to determine their behavior in conditions similar to the human blood plasma. Calcium ion concentration, pH value, microstructure, and phase compositions were analyzed. Results demonstrated that both the crystal Ca-P phases or the amorphous HA do dissolve slightly, and the dissolution of CaO phases in SBF was evident after 1 day of soaking. The calcium-ion concentration was decreased and the pH value of SBF was increased with the increasing of the immersing time. The precipitation was mainly composed of HA, which was verified by X-ray diffraction (XRD) and electron-probe microanalyzer.

  4. Hot corrosion behavior of low pressure plasma sprayed NiCoCrAlY+Ta coatings on nickel base superalloys

    SciTech Connect

    Frances, M.; Steinmetz, P.; Steinmetz, J.; Duret, C.; Mevrel, R.

    1985-11-01

    The hot corrosion behavior of NiCoCrAlY+Ta coatings obtained by low-pressure plasma spraying has been investigated (type I hot corrosion with T = 850/sup 0/C). These coatings have been deposited on two nickel-base superalloys and on a cast alloy of the same composition as the coating. Comparison of the cyclic oxidation behavior at 850/sup 0/C between the sprayed coating and the cast alloy shows that the sprayed material exhibits a satisfactory and higher resistance than the cast alloy. In the latter case, repeated spalling of the oxide scale results from fractures often associated with Y-rich oxide protrusions. Hot corrosion experiments (salt-spraying test with T = 850/sup 0/C and thermal cycling in air every hour) have been conducted on two cast alloys, NiCoCrAl+Ta and NiCoCrAlY+Ta. The Y-containing alloy has a better corrosion resistance than the other alloy which is subject to extensive oxide spallation. In both cases, morphologies typical of basic fluxing processes, involving Cr, Al, Y, and Ta can be observed in highly attacked zones. Finally, tests on plasma sprayed coatings show a high resistance to hot corrosion of these coatings, regardless of the substrate used: a fine adherent alumina layer is formed, and only a limited fluxing of Cr, Al, and Y takes place. The quite different results obtained on cast and sprayed alloys imply that data relative to cast alloys can be unreliable when one wants to predict high temperature behavior and especially lifetimes of overlay coatings.

  5. The effect of water to ethanol feed ratio on physical properties and aerosolization behavior of spray dried cromolyn sodium particles.

    PubMed

    Gilani, Kambiz; Najafabadi, Abdolhossien Rouholamini; Barghi, Mohammadali; Rafiee-Tehrani, Morteza

    2005-05-01

    Cromolyn sodium (CS) was spray dried under constant operation conditions from different water to ethanol feed ratios (50:50-0:100). The spray dried CS samples were characterized for their physicochemical properties including crystallinity, particle size distribution, morphology, density, and water/ethanol content. To determine quantitatively the crystallinity of the powders, an X-ray diffraction (XRD) method was developed using samples with different crystallinity prepared by physical mixing of 100% amorphous and 100% crystalline CS materials. The aerodynamic behavior of the CS samples was determined using an Andersen Cascade Impactor (ACI) with a Spinhaler at an air flow of 60 L/min. Binary mixtures of each spray dried CS powder and Pharmatose 325, a commercial alpha-lactose monohydrate available for DPI formulations, were prepared and in vitro aerosol deposition of the drug from the mixtures was analyzed using ACI to evaluate the effect of carrier on deposition profiles of the spray dried samples. CS spray dried from absolute ethanol exhibited XRD pattern characteristic for crystalline materials and different from patterns of the other samples. The crystallinity of spray dried CS obtained in the presence of water varied from 0% to 28.37%, depending on the ratio of water to ethanol in the feed suspensions. All samples presented different particle size, water/ethanol content, and bulk density values. CS particles spray dried from absolute ethanol presented uniform elongated shape whereas the other samples consisted mainly of particles with irregular shape. Overall, fine particle fraction increased significantly (p < 0.01) with decreasing d50% and water and ethanol content of spray dried CS samples. Significant difference (p < 0.01) in deposition profiles of the drug were observed between corresponding carrier free and carrier blended formulations. The difference in deposition profiles of CS aerosolized from various spray dried samples were described according to

  6. Effect of Impact Angle on Ceramic Deposition Behavior in Composite Cold Spray: A Finite-Element Study

    NASA Astrophysics Data System (ADS)

    Chakrabarty, Rohan; Song, Jun

    2017-10-01

    During the cold spraying of particle-reinforced metal matrix composite coatings (ceramic and metal particles mixture) on metal substrates, ceramic particles may either get embedded in the substrate/deposited coating or may rebound from the substrate surface. In this study, the dependence of the ceramic rebounding phenomenon on the spray angle and its effect on substrate erosion have been analyzed using finite-element analysis. From the numerical simulations, it was found that the ceramic particle density and substrate material strength played the major roles in determining the embedding and ceramic retention behavior. Substrate material erosion also influenced the ceramic retention, and the material loss increased as the impact angles decreased from normal. In general, the results concluded that decreasing the impact angle promoted the retention possibility of ceramics in the substrate. This study provides new theoretical insights into the effect of spray angles on the ceramic retention and suggests a new route toward optimizing the spraying process to increase the ceramic retention in composite coatings cold spray.

  7. Effect of Impact Angle on Ceramic Deposition Behavior in Composite Cold Spray: A Finite-Element Study

    NASA Astrophysics Data System (ADS)

    Chakrabarty, Rohan; Song, Jun

    2017-07-01

    During the cold spraying of particle-reinforced metal matrix composite coatings (ceramic and metal particles mixture) on metal substrates, ceramic particles may either get embedded in the substrate/deposited coating or may rebound from the substrate surface. In this study, the dependence of the ceramic rebounding phenomenon on the spray angle and its effect on substrate erosion have been analyzed using finite-element analysis. From the numerical simulations, it was found that the ceramic particle density and substrate material strength played the major roles in determining the embedding and ceramic retention behavior. Substrate material erosion also influenced the ceramic retention, and the material loss increased as the impact angles decreased from normal. In general, the results concluded that decreasing the impact angle promoted the retention possibility of ceramics in the substrate. This study provides new theoretical insights into the effect of spray angles on the ceramic retention and suggests a new route toward optimizing the spraying process to increase the ceramic retention in composite coatings cold spray.

  8. Preparation and recrystallization behavior of spray-dried co-amorphous naproxen-indomethacin.

    PubMed

    Beyer, Andreas; Radi, Lydia; Grohganz, Holger; Löbmann, Korbinian; Rades, Thomas; Leopold, Claudia S

    2016-07-01

    To improve the dissolution properties and the physical stability of amorphous active pharmaceutical ingredients, small molecule stabilizing agents may be added to prepare co-amorphous systems. The objective of the study was to investigate if spray-drying allows the preparation of co-amorphous drug-drug systems such as naproxen-indomethacin and to examine the influence of the process conditions on the resulting initial sample crystallinity and the recrystallization behavior of the drug(s). For this purpose, the process parameters inlet temperature and pump feed rate were varied according to a 2(2) factorial design and the obtained samples were analyzed with X-ray powder diffractometry and Fourier-transformed infrared spectroscopy. Evaluation of the data revealed that the preparation of fully amorphous samples could be achieved depending on the process conditions. The resulting recrystallization behavior of the samples, such as the total recrystallization rate, the individual recrystallization rates of naproxen and indomethacin as well as the polymorphic form of indomethacin that was formed were influenced by these process conditions. For initially amorphous samples, it was found that naproxen and indomethacin recrystallized almost simultaneously, which supports the theory of formation of drug-drug heterodimers in the co-amorphous phase.

  9. Effect of substrate hardness on the deformation behavior of subsequently incident particles in cold spraying

    NASA Astrophysics Data System (ADS)

    Yin, Shuo; Wang, Xiao-fang; Li, W. Y.; Jie, Hong-en

    2011-06-01

    A systematic finite element analysis (FEA) on the subsequently incident particles which refer to the particles depositing after the formation of the first layer coating is conducted in this study to clarify the bonding mechanism inside the cold sprayed coating. A simplified particle impact model is proposed and the simulated results based on this model demonstrate that substrate hardness exerts some effects on the deformation behavior of the subsequently incident particles. Hard substrate makes these particles deform intensively but using soft substrate enables them to achieve a slight deformation. At the same time, it is also found that substrate hardness plays its best role only when the formed coating is thin, as the development of the coating, the particle deformation behavior becomes more and more insensitive to the substrate hardness. The multi-particle impact simulation based on Eulerian method is also performed and reaches the same conclusion, confirming the accuracy of the simplified model. Besides, it is also found that when the velocity is increased to a hypervelocity, excessive deformation occurs in the formed coatings due to the impact of the subsequently incident particles.

  10. Corrosion behavior of HVOF sprayed hard face coatings in alkaline-sulfide solution

    NASA Astrophysics Data System (ADS)

    Li, Shenhou; Guo, Zhixing; Xiong, Ji; Lei, Yong; Li, Yuxi; Tang, Jun; Liu, Junbo; Ye, Junliu

    2017-09-01

    The paper focuses on the corrosion behavior of high velocity oxygen fuel (HVOF) sprayed WC-17Co, WC-10Co-4Cr, Cr3C2-25NiCr coatings in alkaline-sulfide solution (S2-, 0.2 ml/L, pH = 10). Eighteen days of immersion test is carried out and corrosion rate analysis shows that the Cr3C2-NiCr coating of low porosity exhibits the best corrosion resistance. In alkaline-sulfide solutions, porosity, passive film and microgalvanic between hard phase and binder phase have significant effect on the corrosion behavior of coatings. The corrosion mainly occurs in binder phase from SEM, though WO3, WS2, Cr2S3 are detected in XPS. In WC-17Co coating, the binder phase Co transforms to Co oxides and serious corrosion can be observed in binder phase. WC-10Co-4Cr coatings suffer localized corrosion since galvanic corrosion occurs between locations with different solubilities of W in Co binder. Cr3C2-25NiCr coating shows slight corrosion with the formation of NiS/Ni2O3/Cr2O3from the binder and Cr2S3 from the hard phase. The results are verified by the polarization curves, which show the longest passive region and lowest Icorrosion of Cr3C2-25NiCr coating.

  11. Sintering and Fracture Behavior of Plasma-sprayed Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Choi, Sung R.; Miller, Robert A.

    2004-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. There is a need to characterize the fundamental sintering and fracture behavior of the current ZrO2-(7 to 8)wt%Y2O3 coating, in order to fully take advantage of the coating capability. In addition, a thorough evaluation of the coating behavior and temperature limits will be useful for more accurately assessing the benefit gained from future advanced coating systems. In this study, the sintering behavior of plasma-sprayed ZrO2-8wt%Y2O3 coatings was systematically investigated as a function of temperature and time using a dilatometer in the temperature range of 1200-1500 C. The coating sintering kinetics obtained by dilatometry were compared with the coating thermal conductivity increase kinetics, determined by a steady-state laser heat-flux testing approach, under high temperature and thermal gradient sintering conditions. The mode I, mode II, and mixed mode I-mode II fracture behavior of as-processed and sintering-annealed coatings was determined in asymmetric flexure loading at ambient and elevated temperatures in order to evaluate the coating sintering effects on the fracture envelope of K(sub I) versus K(sub II). The coating thermal conductivity cyclic response associated with the interface delamination of the coating systems under simulated engine heat-flux conditions will be discussed in conjunction with the sintering and fracture testing results.

  12. Connecting grain-scale physics to macroscopic granular flow behavior using discrete contact-dynamics simulations, centrifuge experiments, and continuum modeling

    NASA Astrophysics Data System (ADS)

    Reitz, Meredith; Stark, Colin; Hung, Chi-Yao; Smith, Breannan; Grinspin, Eitan; Capart, Herve; Li, Liming; Crone, Timothy; Hsu, Leslie; Ling, Hoe

    2014-05-01

    A complete theoretical understanding of geophysical granular flow is essential to the reliable assessment of landslide and debris flow hazard and for the design of mitigation strategies, but several key challenges remain. Perhaps the most basic is a general treatment of the processes of internal energy dissipation, which dictate the runout velocity and the shape and scale of the affected area. Currently, dissipation is best described by macroscopic, empirical friction coefficients only indirectly related to the grain-scale physics. Another challenge is describing the forces exerted at the boundaries of the flow, which dictate the entrainment of further debris and the erosion of cohesive surfaces. While the granular effects on these boundary forces have been shown to be large compared to predictions from continuum approximations, the link between granular effects and erosion or entrainment rates has not been settled. Here we present preliminary results of a multi-disciplinary study aimed at improving our understanding of granular flow energy dissipation and boundary forces, through an effort to connect grain-scale physics to macroscopic behaviors. Insights into grain-scale force distributions and energy dissipation mechanisms are derived from discrete contact-dynamics simulations. Macroscopic erosion and flow behaviors are documented from a series of granular flow experiments, in which a rotating drum half-filled with grains is placed within a centrifuge payload, in order to drive effective gravity levels up to ~100g and approach the forces present in natural systems. A continuum equation is used to characterize the flowing layer depth and velocity resulting from the force balance between the down-slope pull of gravity and the friction at the walls. In this presentation we will focus on the effect of granular-specific physics such as force chain networks and grain-grain collisions, derived from the contact dynamics simulations. We will describe our efforts to

  13. Spray granulation: importance of process parameters on in vitro and in vivo behavior of dried nanosuspensions.

    PubMed

    Figueroa, Carlos E; Bose, Sonali

    2013-11-01

    The use of fluid bed granulation for drying of pharmaceutical nanoparticulates on micron-sized granule substrates is a relatively new technique, with limited understanding in the current literature of the effects of process parameters on the physical properties of the dried nanoparticle powders. This work evaluated the effects of spray mode, spray rate and atomizing pressure for spray granulation of drug nanosuspensions through a systematic study. Naproxen and a proprietary Novartis compound were converted into nanosuspensions through wet media milling and dried onto a mannitol based substrate using spray granulation. For naproxen, various physical properties of the granules, as well as the in vitro re-dispersion and dissolution characteristics of the nano-crystals, were measured. It was found that the spray mode had the most drastic effect, where top spray yielded smaller re-dispersed particle sizes and faster release rates of drug from granules than bottom spray. This was attributed to the co-current spraying in bottom spray resulting in denser, homogenous films on the substrate. Similar in vitro results were obtained for the proprietary molecule, Compound A. In vivo studies in beagle dogs with Compound A showed no significant difference between the liquid and the dried forms of the nanosuspension in terms of overall AUC, differences were observed in the tmax which correlated with the rank ordering observed from the in vitro dissolution profiles. These findings make spray granulation amenable to the production of powders with desired processing and handling properties, without compromising the overall exposure of the compound under investigation. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. The properties and fracture behavior of ion plasma sprayed TiN coating on stainless steel substrate

    NASA Astrophysics Data System (ADS)

    Orlova, Dina V.; Goncharenko, Igor M.; Danilov, Vladimir I.; Lobach, Maxim I.; Danilova, Lidiya V.; Shlyakhova, Galina V.

    2015-10-01

    The wear resistance and fracture behavior of ion plasma sprayed TiN coating were studied; the results are presented. The coating was applied to the stainless steel substrate using a vacuum arc method. The samples were tested by active loading. With varying coating thickness, its characteristics were found to change. Multiple cracking would occur in the deformed sample, with fragment borders aligned normal to the extension axis.

  15. High temperature deformation behavior of spray-formed and subsequently extruded Al-25Si based alloy

    NASA Astrophysics Data System (ADS)

    Lee, Sin-Woo; Kim, Mok-Soon

    2016-07-01

    The high temperature deformation behavior of spray-formed and subsequently extruded Al-25Si based alloy containing fine Si and ultra-fine intermetallic phases was examined by compressive tests at temperatures between 523 and 743 K and strain rates between 1.0 × 10-3 and 1.0 × 100/s. The true stress-true strain curves obtained from the compressive tests revealed a peak stress at the initial stage of deformation. The peak stress decreased with increasing temperature or decreasing strain rate. A close relationship was observed between the peak stress and the constitutive equation for high temperature deformation. In the deformed specimens, fine equiaxed grains were observed with a mean grain size of 330 590 nm, which was much finer than that measured prior to deformation (1.4 μm). A dislocation structure within the grains was also observed in the deformed specimens, indicating the occurrence of dynamic recrystallization during high temperature deformation of the present alloy. The occurrence of dynamic recrystallization was also supported by the existence of a peak stress in the flow curve.

  16. Wear behaviors of HVOF sprayed WC-12Co coatings by laser remelting under lubricated condition

    NASA Astrophysics Data System (ADS)

    Dejun, Kong; Tianyuan, Sheng

    2017-03-01

    A HVOF (high velocity oxygen fuel) sprayed WC-12Co coating was remelted with a CO2 laser. The surface-interface morphologies and phases were analyzed by means of SEM (scanning electron microscopy), and XRD (X-ray diffraction), respectively. The friction and wear behaviors of WC-12Co coating under the dry and lubricated conditions were investigated with a wear test. The morphologies and distributions of chemical elements on worn scar were analyzed with a SEM, and its configured EDS (energy diffusive spectrometer), respectively, and the effects of lubricated condition on COFs (coefficient of friction) and wear performance were also discussed. The results show that the adhesion between the coating and the substrate is stronger after laser remetling (LR), in which mechanical bonding, accompanying with metallurgical bonding, was found. At the load of 80 N, the average COF under the dry and lubricated friction conditions is 0.069, and 0.052, respectively, the latter lowers by 23.3% than the former, and the wear rate under the lubricated condition decreases by 302.3% than that under the dry condition. The wear mechanism under the dry and lubrication conditions is primarily composed of abrasive wear, cracking, and fatigue failure.

  17. Precipitation Behavior and Quenching Sensitivity of a Spray Deposited Al-Zn-Mg-Cu-Zr Alloy

    PubMed Central

    Lei, Qian; Xiao, Zhu; Wang, Mingpu

    2017-01-01

    Precipitation behavior and the quenching sensitivity of a spray deposited Al-Zn-Mg-Cu-Zr alloy during isothermal heat treatment have been studied systematically. Results demonstrate that both the hardness and the ultimate tensile strength of the studied alloy decreased with the isothermal treatment time at certain temperatures. More notably, the hardness decreases rapidly after the isothermal heat treatment. During isothermal heat treatment processing, precipitates readily nucleated in the medium-temperature zone (250–400 °C), while the precipitation nucleation was scarce in the low-temperature zone (<250 °C) and in the high-temperature zone (>400 °C). Precipitates with sizes of less than ten nanometers would contribute a significant increase in yield strength, while the ones with a larger size than 300 nm would contribute little strengthening effect. Quenching sensitivity is high in the medium-temperature zone (250–400 °C), and corresponding time-temperature-property (TTP) curves of the studied alloy have been established. PMID:28925964

  18. Effect of Load on Friction-Wear Behavior of HVOF-Sprayed WC-12Co Coatings

    NASA Astrophysics Data System (ADS)

    Yifu, Jin; Weicheng, Kong; Tianyuan, Sheng; Ruihong, Zhang; Dejun, Kong

    2017-07-01

    A WC-12Co coating was sprayed on AISI H13 hot work mold steel using a high-velocity oxygen fuel. The morphologies, phase compositions, and distributions of chemical elements of the obtained coatings were analyzed using a field emission scanning electron microscope, x-ray diffraction, and energy-dispersive spectroscope (EDS), respectively. The friction-wear behaviors under different loads were investigated using a reciprocating wear tester; the morphologies and distributions of the chemical elements of worn tracks were analyzed using a SEM and its configured EDS, respectively. The results show the reunited grains of WC are held together by the Co binder; the primary phases of the coating are WC, Co, and a small amount of W2C and W, owing to the oxidation and decarburization of WC. Inter-diffusion of Fe and W between the coating and the substrate is shown, which indicates a good coating adhesion. The values of the average coefficient of friction under the loads of 40, 80, and 120 N are 0.29, 0.31, and 0.49, respectively. The WC grains are pulled out of the coating during the sliding wear test, but the coating maintains its integrity, suggesting that the coating is intact and continuously protects the substrate from wearing.

  19. The low cycle fatigue behavior of a plasma-sprayed coating material

    NASA Technical Reports Server (NTRS)

    Gayda, J.; Gabb, T. P.; Miner, R. V., Jr.

    1986-01-01

    Single crystal nickel-base superalloys employed in turbine blade applications are often used with a plasma spray coating for oxidation and hot corrosion resistance. These coatings may also affect fatigue life of the superalloy substrate. As part of a large program to understand the fatigue behavior of coated single crystals, fully reversed, total strain controlled fatigue tests were run on a free standing NiCoCrAlY coating alloy, PWA 276, at 0.1 Hz. Fatigue tests were conducted at 650 C, where the NiCoCrAlY alloy has modest ductility, and at 1050 C, where it is extremely ductile, showing tensile elongation in excess of 100 percent. At the lower test temperature, deformation induced disordering softened the NiCoCrAlY alloy, while at the higher test temperature cyclic hardening was observed which was linked to gradual coarsening of the two phase microstructure. Fatigue life of the NiCoCrAlY alloy was significantly longer at the higher temperature. Further, the life of the NiCoCrAlY alloy exceeds that of coated, /001/-oriented PWA 1480 single crystals at 1050 C, but at 650 C the life of the coated crystal is greater than that of the NiCoCrAlY alloy on a total strain basis.

  20. Macroscopic Potentials for Charged Swelling Porous Media

    NASA Astrophysics Data System (ADS)

    Bennethum, L. S.

    2011-12-01

    Here we discuss the macroscopic potentials that induce bulk fluid flow through swelling porous materials. Swelling porous media such as expansive soils, food stuff, biotissue, and swelling polymers have complex microstructure such as a possibly charged solid surface and a large liquid-solid interfacial area density causing the solid-liquid interaction to affect macroscopic behavior. Here we discuss the macroscopic pressures and chemical potentials that produce flow within the framework of hybrid mixture theory.

  1. Sprayed intraperitoneal bupivacaine reduces early postoperative pain behavior and biochemical stress response after laparoscopic ovariohysterectomy in dogs.

    PubMed

    Kim, Young K; Lee, Scott S; Suh, Euy H; Lee, Lyon; Lee, Hee C; Lee, Hyo J; Yeon, Seong C

    2012-02-01

    This study investigated the use of sprayed intraperitoneal bupivacaine to relieve postoperative pain behavior and biochemical stress response after laparoscopic ovariohysterectomy (LOVH) in dogs. Sixteen sexually intact female dogs were randomly assigned to two groups. The sprayed intraperitoneal bupivacaine (SIB) group received 4.4 mg/kg of sprayed intraperitoneal bupivacaine diluted to 0.25% with an equivalent volume of saline after pneumoperitoneum. The control group received 1.76 mL/kg of saline in a similar fashion. Both groups received preoperative periportal 5% bupivacaine (1 mL) before incision. Postoperative pain was measured using the short form of the Glasgow composite measures pain scale (CMPS-SF, 0-24). Serum cortisol and glucose concentrations were measured preoperatively and 0.5, 1, 2, 4, 6, 12, and 24h postoperatively. The SIB group had significantly lower CMPS-SF compared to the control group 1, 2, 4, 6, and 12h after the operation. Cortisol concentrations were significantly increased from preoperative concentrations in the control group at 0.5, 1, 2, and 4h post operation and at 0.5 and 1h post operation in the SIB group. No significant differences were seen in serum glucose within each group. This report suggests that the use of sprayed intraperitoneal bupivacaine can be used as part of a multimodal approach for pain management after LOVH in dogs. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Preparation of Aluminum Coatings by Atmospheric Plasma Spraying and Dry-Ice Blasting and Their Corrosion Behavior

    NASA Astrophysics Data System (ADS)

    Dong, Shu-Juan; Song, Bo; Zhou, Gen-Shu; Li, Chang-Jiu; Hansz, Bernard; Liao, Han-Lin; Coddet, Christian

    2013-10-01

    Aluminum coating, as an example of spray coating material with low hardness, was deposited by atmospheric plasma spraying while dry-ice blasting was applied during the deposition process. The deposited coatings were characterized in terms of microstructure, porosity, phase composition, and the valence states. The results show that the APS aluminum coatings with dry-ice blasting present a porosity of 0.35 ± 0.02%, which is comparable to the bulk material formed by the mechanical compaction. In addition, no evident oxide has been detected, except for the very thin and impervious oxide layer at the outermost layer. Compared to plasma-sprayed Al coatings without dry-ice blasting, the adhesion increased by 52% for Al substrate using dry-ice blasting, while 25% for steel substrate. Corrosion behavior of coated samples was evaluated in 3.5 wt.% NaCl aqueous using electrochemistry measurements. The electrochemical results indicated that APS Al coating with dry-ice blasting was more resistant to pitting corrosion than the conventional plasma-sprayed Al coating.

  3. Macroscopic magnetic frustration.

    PubMed

    Mellado, Paula; Concha, Andres; Mahadevan, L

    2012-12-21

    Although geometrical frustration transcends scale, it has primarily been evoked in the micro- and mesoscopic realm to characterize such phases as spin ice, liquids, and glasses and to explain the behavior of such materials as multiferroics, high-temperature superconductors, colloids, and copolymers. Here we introduce a system of macroscopic ferromagnetic rotors arranged in a planar lattice capable of out-of-plane movement that exhibit the characteristic honeycomb spin ice rules studied and seen so far only in its mesoscopic manifestation. We find that a polarized initial state of this system settles into the honeycomb spin ice phase with relaxation on multiple time scales. We explain this relaxation process using a minimal classical mechanical model that includes Coulombic interactions between magnetic charges located at the ends of the magnets and viscous dissipation at the hinges. Our study shows how macroscopic frustration arises in a purely classical setting that is amenable to experiment, easy manipulation, theory, and computation, and shows phenomena that are not visible in their microscopic counterparts.

  4. Microstructure and Room Temperature Compressive Deformation Behavior of Cold-Sprayed High-Strength Cu Bulk Material

    NASA Astrophysics Data System (ADS)

    Kim, Young-Kyun; Kim, Kyu-Sik; Kim, Hyung-Jun; Park, Chan-Hee; Lee, Kee-Ahn

    2017-08-01

    This study investigated the room temperature compressive deformation behavior of Cu bulk material manufactured by cold spray process. Initial microstructural observation identified a unique microstructure with grain size of hundreds of nm in the particle interface area and relatively coarse grains in all other areas. Room temperature compressive results confirmed cold-sprayed Cu to have a yield strength of 340 MPa, which is similar to materials manufactured by severe plastic deformation process such as equal channel angular press. In addition, strain softening phenomenon, which is rarely found in room temperature compressive deformation, was observed. According to such unique characteristics, continuous microstructure evolution and surface fractures according to the strain (ɛ t = 0.3/0.6/0.9) of the material were observed, and considerations were made for deformation and fracture behavior. Microstructural observation after compressive deformation confirmed that average grain size decreased as the strain increased, and the fraction of the low-angle boundary, which has an indirect relationship with dislocation density, showed a tendency to decrease in ɛ t = 0.3-0.6 region where the strain softening phenomenon occurs. Based on the results described above, this study was able to identify the possibility of manufacturing cold-sprayed Cu bulk material for structural material and its room temperature deformation behavior.

  5. Electrochemical behavior of different preparations of plasma-sprayed hydroxyapatite coatings on Ti6Al4V substrate.

    PubMed

    Souto, Ricardo M; Lemus, M Mercedes; Reis, Rui L

    2004-07-01

    The corrosion behavior of four different preparations of plasma-sprayed hydroxyapatite (HA) coatings on Ti6Al4V substrates in static Hank's balanced salt solution was investigated using dc potentiodynamic and ac impedance techniques. Two different nominal thicknesses, 50 microm and 200 microm, and two different spraying conditions, were considered. The electrochemical impedance experiments proved this technique to be very suitable for the investigation of the electrochemical behavior of surgical implant alloys when they are coated with HA, which is characterized by the dissolution and passivation characteristics of the underlying metal substrate. Because the coatings are porous, ionic paths between the electrolytic medium and the base material can eventually be produced, resulting in the corrosion of the coated metal. Differences in the corrosion resistance of the coated materials were detected, and a relevant model for the description of the coating degradation in the biosimulating solution was proposed. The model consisted of the description of the coated system in terms of a two-layer model of the surface film. Significant differences in electrochemical behavior for similar nominal thicknesses of HA coatings obtained under different spraying conditions were found.

  6. Microstructure and Room Temperature Compressive Deformation Behavior of Cold-Sprayed High-Strength Cu Bulk Material

    NASA Astrophysics Data System (ADS)

    Kim, Young-Kyun; Kim, Kyu-Sik; Kim, Hyung-Jun; Park, Chan-Hee; Lee, Kee-Ahn

    2017-10-01

    This study investigated the room temperature compressive deformation behavior of Cu bulk material manufactured by cold spray process. Initial microstructural observation identified a unique microstructure with grain size of hundreds of nm in the particle interface area and relatively coarse grains in all other areas. Room temperature compressive results confirmed cold-sprayed Cu to have a yield strength of 340 MPa, which is similar to materials manufactured by severe plastic deformation process such as equal channel angular press. In addition, strain softening phenomenon, which is rarely found in room temperature compressive deformation, was observed. According to such unique characteristics, continuous microstructure evolution and surface fractures according to the strain ( ɛ t = 0.3/0.6/0.9) of the material were observed, and considerations were made for deformation and fracture behavior. Microstructural observation after compressive deformation confirmed that average grain size decreased as the strain increased, and the fraction of the low-angle boundary, which has an indirect relationship with dislocation density, showed a tendency to decrease in ɛ t = 0.3-0.6 region where the strain softening phenomenon occurs. Based on the results described above, this study was able to identify the possibility of manufacturing cold-sprayed Cu bulk material for structural material and its room temperature deformation behavior.

  7. An Analysis of the Macroscopic Tensile Behavior of a Nonlinear Nylon Reinforced Elastomeric Composite System Using MAC/GMC

    NASA Technical Reports Server (NTRS)

    Assaad, Mahmoud; Arnold, Steven M.

    1999-01-01

    A special class of composite laminates composed of soft rubbery matrices and stiff reinforcements made of steel wires or synthetic fibers is examined, where each constituent behaves in a nonlinear fashion even in the small strain domain. Composite laminates made of piles stacked at alternating small orientation angles with respect to the applied axial strain are primarily dominated by the nonlinear behavior of the reinforcing fibers. However; composites with large ply orientations or those perpendicular to the loading axis, will approximate the behavior of the matrix phase and respond in even a more complex fashion for arbitrarily stacked piles. The geometric nonlinearity due to small cord rotations during loading was deemed here to have a second order effect and consequently dropped from any consideration. The user subroutine USRMAT within the Micromechanics Analysis Code with the Generalized Method of Cells (MAC/GMC), was utilized to introduce the constituent material nonlinear behavior. Stress-strain behavior at the macro level was experimentally generated for single and multi ply composites comprised of continuous Nylon-66 reinforcements embedded in a carbon black loaded rubbery matrix. Comparisons between the predicted macro composite behavior and experimental results are excellent when material nonlinearity is included in the analysis. In this paper, a brief review of GMC is provided, along with a description of the nonlinear behavior of the constituents and associated constituent constitutive relations, and the improved macro (or composite) behavior predictions are documented and illustrated.

  8. Influence of coating defects on the corrosion behavior of cold sprayed refractory metals

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Rao, A. Arjuna

    2017-02-01

    The defects in the cold sprayed coatings are critical in the case of corrosion performances of the coatings in aggressive conditions. To understand the influence of coating defects on corrosion, immersion tests have been carried out in HF solution for the cold sprayed and heat treated Titanium, Tantalum and Niobium coatings. Long duration immersion tests reveal inhomogeneous weight losses of the samples prepared at different heat treatment conditions. The weight loss for different coatings has been well corroborated with the coating defects and microstructures. Chemical and micro structural analysis elucidates the reason behind the inhomogeneous performance of different type of cold sprayed coatings in corrosion medium. In the case of cold sprayed titanium, formation of stable oxide along the inter-splat boundary hinders the aggressive attack of the corrosion medium which is not so in other cases.

  9. Mechanical and Microstructural Behavior of Cold-Sprayed Titanium- and Nickel-Based Coatings

    NASA Astrophysics Data System (ADS)

    Cavaliere, P.; Silvello, A.

    2015-12-01

    Cold spraying is a coating technology that can deposit materials with unique properties. The coating forms through intensive plastic deformation of particles impacting on a substrate at temperature well below the melting point of the sprayed material. Recently, various studies have been published regarding the microstructural and mechanical evolution of metal-matrix composite coatings produced by cold spraying. Herein, we describe the principal results of the available literature in the field of cold-sprayed composites. It is shown that more research is required to solve various questions in this field, for example, the different deformation modes of the material exhibited for various processing conditions, the reinforcing percentage of different material combinations, and the mechanical properties resulting from these complex systems. In the present study, this issue is approached and described for cold-sprayed Ni- and Ti-based composites. Materials were produced with varying ceramic phase (BN and TiAl3) fraction. The variation of the grain size, adhesion strength, porosity, and hardness of the deposits as a function of the ceramic phase fraction and processing parameters (impacting particle speed) is described. The interaction mechanisms between the cold-sprayed particles and the metal matrix during the coating process are presented and described. The results demonstrate a beneficial effect on grain size and porosity with increasing reinforcing phase percentage, as well as narrow processing parameter ranges to achieve the optimal properties with respect to the pure parent materials.

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

    NASA Astrophysics Data System (ADS)

    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 <2% of that of the 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.

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

    NASA Astrophysics Data System (ADS)

    Sidhu, Buta Singh; Prakash, S.

    2006-06-01

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

  12. Investigation of the changes in aerosolization behavior between the jet-milled and spray-dried colistin powders through surface energy characterization

    PubMed Central

    Jong, Teresa; Li, Jian; Mortonx, David A.V.; Zhou, Qi (Tony); Larson, Ian

    2016-01-01

    This study aimed to investigate the surface energy factors behind improved aerosolization performance of spray-dried colistin powder formulations compared to those produced by jet-milling. Inhalable colistin powder formulations were produced by jet-milling or spray-drying (with or without L-leucine). Scanning electron micrographs showed the jet-milled particles had irregularly angular shapes, while the spray-dried particles were more spherical. Significantly higher fine particle fractions (FPFs) were measured for the spray-dried (43.8-49.6%) vs. the jet-milled formulation (28.4 %) from a Rotahaler at 60L/min; albeit the size distribution of the jet-milled powder was smaller. Surprisingly, addition of L-leucine in the spray drying feed-solution gave no significant improvement in FPF. As measured by inverse gas chromatography, spray-dried formulations had significantly (p<0.001) lower dispersive, specific and total surface energy values and more uniform surface energy distributions than the jet-milled powder. Interestingly, no significant difference was measured in the specific and total surface energy values between the spray-dried formulation with or without L-leucine. Based upon our previous findings in the self-assembling behavior of colistin in aqueous solution and the surface energy data obtained here, we propose the self-assembly of colistin molecules during spray-drying, contributed significantly to the reduction of surface free energy and the superior aerosolization performance. PMID:26886330

  13. A macroscopic violation of no-signaling in time inequalities? How to test temporal entanglement with behavioral observables

    PubMed Central

    Tressoldi, Patrizio E.; Maier, Markus A.; Buechner, Vanessa L.; Khrennikov, Andrei

    2015-01-01

    In this paper we applied for the first time the no-signaling in time (NSIT) formalism discussed by Kofler and Brukner (2013) to investigate temporal entanglement between binary human behavioral unconscious choices at t1 with binary random outcomes at t2. NSIT consists of a set of inequalities and represents mathematical conditions for macro-realism which require only two measurements in time. The analyses of three independent experiments show a strong violation of NSIT in two out of three of them, suggesting the hypothesis of a quantum-like temporal entanglement between human choices at t1 with binary random outcomes at t2. We discuss the potentialities of using NSIT to test temporal entanglement with behavioral measures. PMID:26283993

  14. The consequences of dependence between the formal area efficiency and the macroscopic electric field on linearity behavior in Fowler-Nordheim plots

    NASA Astrophysics Data System (ADS)

    de Assis, Thiago A.; Dall'Agnol, Fernando F.; Andrade, Roberto F. S.

    2016-09-01

    This work presents a theoretical explanation for a crossover in the linear behavior in Fowler-Nordheim (FN) plots based on orthodox cold field electron emission (CFE) experimental data. It is characterized by a clear change in the decay rate of usually single-slope FN plots, and has been reported when non-uniform nano-emitters are subject to high macroscopic electric field F M. We assume that the number of emitting spots, which defines an apparent formal area efficiency of CFE surfaces, depends on the macroscopic electric field. Non-uniformity is described by local enhancement factors ≤ft\\{{γj}\\right\\} , which are randomly assigned to each distinct emitter of a conducting CFE surface, from a discrete probability distribution ρ ≤ft({γj}\\right) , with j  =  1, 2. It is assumed that ρ ≤ft({γ1}\\right)<ρ ≤ft({γ2}\\right) , and that {γ1}>{γ2} . The local current density is evaluated by considering a usual Schottky-Nordheim barrier. The results reproduce the two distinct slope regimes in FN plots when {{F}\\text{M}}\\in [2, 20] V μm-1 and are analyzed by taking into account the apparent formal area efficiency, the distribution ρ, and the slopes in the corresponding FN plot. Finally, we remark that our results from numerical solution of Laplace’s equation, for an array of conducting nano-emitters with uniform apex radii 50 nm but different local height, supports our theoretical assumptions and could used in orthodox CFE experiments to test our predictions.

  15. A Possible Link Between Macroscopic Wear and Temperature Dependent Friction Behaviors of MoS2 Coatings

    DTIC Science & Technology

    2008-09-01

    Alvarez Æ Nathan A. Mauntler Æ Nicolas Argibay Æ Rachel Colbert Æ David L. Burris Æ Chris Muratore Æ Andrey A. Voevodin Æ Scott S. Perry Æ W. Gregory...composites. Wear 153, 229–243 (1992). doi:10.1016/0043-1648(92)90271-9 14. McLaren, K., Tabor , D.: Visco-elastic properties and friction of solids—friction of...polymers—influence of speed and tempera- ture. Nature 197, 856–858 (1963) 15. Pooley, C.M., Tabor , D.: Friction and molecular structure— behavior of

  16. Cracking and Spalling Behavior of HVOF Thermally Sprayed WC-Co-Cr Coating in Bend and Axial Fatigue Tests

    NASA Astrophysics Data System (ADS)

    Gui, M.; Eybel, R.; Asselin, B.; Monerie-Moulin, F.

    2015-03-01

    In this work, WC-10Co-4Cr coating was sprayed by high-velocity oxygen fuel (HVOF) process on Almen strip and axial fatigue coupon. Three-point bend test was used to bend Almen strip coating specimens with tensile and compressive stress applied to the coating. Axial fatigue coating specimens were tested at a load stress of 1250 MPa and a stress ratio of R = -1. Process condition of Thermal spraying was found to have an effect on spalling performance of the coating in the fatigue test. The mechanism of cracking and spalling process in the coating was studied in bend and fatigue conditions. Based on deformation difference between the coating and the substrate, the factors, especially coating thickness, to impact the coating spalling behavior in axial fatigue test are discussed. HVOF-sprayed WC-10Co-4Cr coating matches the deformation of base substrate by cracking when tensile stress is applied in bend and fatigue tests because the coating has very limit deformation capability. In axial fatigue test of WC-10Co-4Cr coating specimen, the substrate works in a stress-to-strain manner; however the coating works in a strain-to-stress manner and is stressed due to the substrate deformation.

  17. Critical Deposition Condition of CoNiCrAlY Cold Spray Based on Particle Deformation Behavior

    NASA Astrophysics Data System (ADS)

    Ichikawa, Yuji; Ogawa, Kazuhiro

    2017-02-01

    Previous research has demonstrated deposition of MCrAlY coating via the cold spray process; however, the deposition mechanism of cold spraying has not been clearly explained—only empirically described by impact velocity. The purpose of this study was to elucidate the critical deposit condition. Microscale experimental measurements of individual particle deposit dimensions were incorporated with numerical simulation to investigate particle deformation behavior. Dimensional parameters were determined from scanning electron microscopy analysis of focused ion beam-fabricated cross sections of deposited particles to describe the deposition threshold. From Johnson-Cook finite element method simulation results, there is a direct correlation between the dimensional parameters and the impact velocity. Therefore, the critical velocity can describe the deposition threshold. Moreover, the maximum equivalent plastic strain is also strongly dependent on the impact velocity. Thus, the threshold condition required for particle deposition can instead be represented by the equivalent plastic strain of the particle and substrate. For particle-substrate combinations of similar materials, the substrate is more difficult to deform. Thus, this study establishes that the dominant factor of particle deposition in the cold spray process is the maximum equivalent plastic strain of the substrate, which occurs during impact and deformation.

  18. Critical Deposition Condition of CoNiCrAlY Cold Spray Based on Particle Deformation Behavior

    NASA Astrophysics Data System (ADS)

    Ichikawa, Yuji; Ogawa, Kazuhiro

    2016-12-01

    Previous research has demonstrated deposition of MCrAlY coating via the cold spray process; however, the deposition mechanism of cold spraying has not been clearly explained—only empirically described by impact velocity. The purpose of this study was to elucidate the critical deposit condition. Microscale experimental measurements of individual particle deposit dimensions were incorporated with numerical simulation to investigate particle deformation behavior. Dimensional parameters were determined from scanning electron microscopy analysis of focused ion beam-fabricated cross sections of deposited particles to describe the deposition threshold. From Johnson-Cook finite element method simulation results, there is a direct correlation between the dimensional parameters and the impact velocity. Therefore, the critical velocity can describe the deposition threshold. Moreover, the maximum equivalent plastic strain is also strongly dependent on the impact velocity. Thus, the threshold condition required for particle deposition can instead be represented by the equivalent plastic strain of the particle and substrate. For particle-substrate combinations of similar materials, the substrate is more difficult to deform. Thus, this study establishes that the dominant factor of particle deposition in the cold spray process is the maximum equivalent plastic strain of the substrate, which occurs during impact and deformation.

  19. Electrochemical Corrosion Behavior of Spray-Formed Boron-Modified Supermartensitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Zepon, Guilherme; Nogueira, Ricardo P.; Kiminami, Claudio S.; Botta, Walter J.; Bolfarini, Claudemiro

    2017-04-01

    Spray-formed boron-modified supermartensitic stainless steel (SMSS) grades are alloys developed to withstand severe wear conditions. The addition of boron to the conventional chemical composition of SMSS, combined with the solidification features promoted by the spray forming process, leads to a microstructure composed of low carbon martensitic matrix reinforced by an eutectic network of M2B-type borides, which considerably increases the wear resistance of the stainless steel. Although the presence of borides in the microstructure has a very beneficial effect on the wear properties of the alloy, their effect on the corrosion resistance of the stainless steel was not comprehensively evaluated. The present work presents a study of the effect of boron addition on the corrosion resistance of the spray-formed boron-modified SMSS grades by means of electrochemical techniques. The borides fraction seems to have some influence on the repassivation kinetics of the spray-formed boron-modified SMSS. It was shown that the Cr content of the martensitic matrix is the microstructural feature deciding the corrosion resistance of this sort of alloys. Therefore, if the Cr content in the alloy is increased to around 14 wt pct to compensate for the boron consumed by the borides formation, the corrosion resistance of the alloy is kept at the same level of the alloy without boron addition.

  20. Influences of Turbulence Characteristic on the Dispersion Behavior of Droplets in the Spray Flame

    NASA Astrophysics Data System (ADS)

    Takeuchi, Seiichi; Douhara, Noriyoshi

    The authors investigated the effect of the turbulence of an air current on droplet dispersion in a spray flame. Wire meshes of different mesh sizes were inserted behind a two-fluid type nozzle each time to vary the air current turbulence characteristics, and then methanol was sprayed to form a spray flame. Droplets in the spray flame were measured with a Phase Doppler Particle Analyzer (PDPA). In the no-reaction field, the turbulence characteristics were measured by using a hot wire anemometer to determine the influences of the turbulence on droplet dispersion in a flame. As the mesh size of the wire mesh was reduced in the investigation, the droplet dispersion was shown to reduce the volume of cluster and also the number density of the droplets. Measuring the turbulence statistics confirmed a decrease of the Stokes number in proportion to the mesh size of the wire mesh. Droplet flying trajectories through turbulence were calculated. According to the calculation results, inserting a finer wire mesh was found to move flying trajectories closer to the streamline of the vortex. When a finer wire mesh was inserted, droplets were drawn closer to the vortex and formed clusters near the vortex. Consequently, droplets were found to disintegrate and disperse under the great in fluences of a vortex.

  1. Electrochemical Corrosion Behavior of Spray-Formed Boron-Modified Supermartensitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Zepon, Guilherme; Nogueira, Ricardo P.; Kiminami, Claudio S.; Botta, Walter J.; Bolfarini, Claudemiro

    2017-01-01

    Spray-formed boron-modified supermartensitic stainless steel (SMSS) grades are alloys developed to withstand severe wear conditions. The addition of boron to the conventional chemical composition of SMSS, combined with the solidification features promoted by the spray forming process, leads to a microstructure composed of low carbon martensitic matrix reinforced by an eutectic network of M2B-type borides, which considerably increases the wear resistance of the stainless steel. Although the presence of borides in the microstructure has a very beneficial effect on the wear properties of the alloy, their effect on the corrosion resistance of the stainless steel was not comprehensively evaluated. The present work presents a study of the effect of boron addition on the corrosion resistance of the spray-formed boron-modified SMSS grades by means of electrochemical techniques. The borides fraction seems to have some influence on the repassivation kinetics of the spray-formed boron-modified SMSS. It was shown that the Cr content of the martensitic matrix is the microstructural feature deciding the corrosion resistance of this sort of alloys. Therefore, if the Cr content in the alloy is increased to around 14 wt pct to compensate for the boron consumed by the borides formation, the corrosion resistance of the alloy is kept at the same level of the alloy without boron addition.

  2. Numerical Investigation of the Macroscopic Mechanical Behavior of NiTi-Hybrid Composites Subjected to Static Load-Unload-Reload Path

    NASA Astrophysics Data System (ADS)

    Taheri-Behrooz, Fathollah; Kiani, Ali

    2017-04-01

    Shape memory alloys (SMAs) are a type of shape memory materials that recover large deformation and return to their primary shape by rising temperature. In the current research, the effect of embedding SMA wires on the macroscopic mechanical behavior of glass-epoxy composites is investigated through finite element simulations. A perfect interface between SMA wires and the host composite is assumed. Effects of various parameters such as SMA wires volume fraction, SMA wires pre-strain and temperature are investigated during loading-unloading and reloading steps by employing ANSYS software. In order to quantify the extent of induced compressive stress in the host composite and residual tensile stress in the SMA wires, a theoretical approach is presented. Finally, it was shown that smart structures fabricated using composite layers and pre-strained SMA wires exhibited overall stiffness reduction at both ambient and elevated temperatures which were increased by adding SMA volume fraction. Also, the induced compressive stress on the host composite was increased remarkably using 4% pre-strained SMA wires at elevated temperature. Results obtained by FE simulations were in good correlation with the rule of mixture predictions and available experimental data in the literature.

  3. Numerical Investigation of the Macroscopic Mechanical Behavior of NiTi-Hybrid Composites Subjected to Static Load-Unload-Reload Path

    NASA Astrophysics Data System (ADS)

    Taheri-Behrooz, Fathollah; Kiani, Ali

    2017-02-01

    Shape memory alloys (SMAs) are a type of shape memory materials that recover large deformation and return to their primary shape by rising temperature. In the current research, the effect of embedding SMA wires on the macroscopic mechanical behavior of glass-epoxy composites is investigated through finite element simulations. A perfect interface between SMA wires and the host composite is assumed. Effects of various parameters such as SMA wires volume fraction, SMA wires pre-strain and temperature are investigated during loading-unloading and reloading steps by employing ANSYS software. In order to quantify the extent of induced compressive stress in the host composite and residual tensile stress in the SMA wires, a theoretical approach is presented. Finally, it was shown that smart structures fabricated using composite layers and pre-strained SMA wires exhibited overall stiffness reduction at both ambient and elevated temperatures which were increased by adding SMA volume fraction. Also, the induced compressive stress on the host composite was increased remarkably using 4% pre-strained SMA wires at elevated temperature. Results obtained by FE simulations were in good correlation with the rule of mixture predictions and available experimental data in the literature.

  4. Investigations of Local Corrosion Behavior of Plasma-Sprayed FeCr Nanocomposite Coating by SECM

    NASA Astrophysics Data System (ADS)

    Shi, Xi; Shu, Mingyong; Zhong, Qingdong; Zhang, Junliang; Zhou, Qiongyu; Bui, Quoc Binh

    2016-02-01

    FeCr alloy coating can be sprayed on low-carbon steel to improve the corrosion resistance because of FeCr alloy's high anti-corrosion capacity. In this paper, Fe microparticles/Cr nanoparticles coating (NFC) and FeCr microparticles coating (MFC) were prepared by atmospheric plasma spraying and NFC was heat-treated under hydrogen atmosphere at 800 °C (HNFC). EDS mapping showed no penetration of Ni in MFC and NFC while penetration of Ni occurred in HNFC. X-ray diffraction results indicated the form of the NiCrFe (bcc) solid solution in HNFC. SECM testing in 3.5 (wt.%) NaCl revealed that the anti-corrosion capacity of NFC improved compared with MFC, while HNFC improved further.

  5. Cold-Sprayed Cu-MoS2 and Its Fretting Wear Behavior

    NASA Astrophysics Data System (ADS)

    Zhang, Yinyin; Descartes, Sylvie; Vo, Phuong; Chromik, Richard R.

    2016-02-01

    Cu and Cu-MoS2 coatings were fabricated by cold spray, and the fretting wear performance of the two coatings was compared. A mixture (95 wt.% Cu + 5 wt.% MoS2) was used as feedstock for the composite coating. Coatings were sprayed with identical gas flow conditions on the substrates pre-heated to approximately 170 °C. The morphology of coating top surface and polished cross sections was analyzed by scanning electron microscopy (SEM) and light optical microscopy (LOM). The influence of MoS2 on Cu deposition was examined. The local MoS2 concentration within the coating was found to affect the hardness. Fretting tests were carried out at two different normal loads, and the influence of MoS2 on friction and wear was studied. The morphology and elemental compositions of the wear scars and wear debris were observed by SEM and energy dispersive x-ray spectroscopy (EDS), respectively.

  6. Fuel Surrogate Physical Property Effects on Direct Injection Spray and Ignition Behavior

    DTIC Science & Technology

    2015-09-01

    emissions, and spray characteristics to the properties of alternative diesel fuels, such as dimethyl ether ( DME ), biodiesel, and jet fuel, which are... kinetic energy flow rate from the fuel injection (Ėkinetic,injection) as follows: fuel fuelU ρ 1 ∝ (Eq. 5) fuelfuelm ρ∝ (Eq. 6) ( ) fuel...fuelfuelinjectionkinetic UmE ρ 12 , ∝∝  (Eq. 7) 15 UNCLASSIFIED UNCLASSIFIED As indicated by Equation 7, the kinetic energy introduced by the fuel

  7. Thermal behavior and stability of biodegradable spray-dried microparticles containing triamcinolone.

    PubMed

    da Silva, Arnóbio Antônio; de Matos, Jivaldo Rosário; Formariz, Thalita Pedroni; Rossanezi, Gustavo; Scarpa, Maria Virginia; do Egito, Eryvaldo Sócrates Tabosa; de Oliveira, Anselmo Gomes

    2009-02-23

    Thermal analysis has been widely used for obtaining information about drug-polymer interactions and for pre-formulation studies of pharmaceutical dosage forms. In this work, biodegradable microparticles of poly (d,L-lactide-co-glycolide) (PLGA) containing triamcinolone (TR) in various drug:polymer ratios were produced by spray drying. The main purpose of this study was to study the effect of the spray-drying process not only on the drug-polymer interactions but also on the stability of microparticles using differential scanning calorimetry (DSC), thermogravimetry (TG) and derivative thermogravimetry (DTG), X-ray analysis (XRD), and infrared spectroscopy (IR). The evaluation of drug-polymer interactions and the pre-formulation studies were assessed using the DSC, TG and DTG, and IR. The quantitative analysis of drugs entrapped in PLGA microparticles was performed by the HPLC method. The results showed high levels of drug-loading efficiency for all used drug:polymer ratio, and the polymorph used for preparing the microparticles was the form B. The DSC and TG/DTG profiles for drug-loaded microparticles were very similar to those for the physical mixtures of the components. Therefore, a correlation between drug content and the structural and thermal properties of drug-loaded PLGA microparticles was established. These data indicate that the spray-drying technique does not affect the physico-chemical stability of the microparticle components. These results are in agreement with the IR analysis demonstrating that no significant chemical interaction occurs between TR and PLGA in both physical mixtures and microparticles. The results of the X-ray analysis are in agreement with the thermal analysis data showing that the amorphous form of TR prevails over a small fraction of crystalline phase of the drug also present in the TR-loaded microparticles. From the pre-formulation studies, we have found that the spray-drying methodology is an efficient process for obtaining TR

  8. Corrosion Behavior of Detonation Gun Sprayed Al Coating on Sintered NFeB

    NASA Astrophysics Data System (ADS)

    Ma, Jizhao; Liu, Xiaofang; Qu, Wentao; Zhou, Chungen

    2015-02-01

    Pure Al coating was prepared by a detonation gun (D-gun) spraying process to protect sintered NdFeB magnets. The detonation gun sprayed coating is very uniform and has a low porosity of 0.77%. The thickness of the Al coating is approximately 16 μm. The corrosion current density for the coated sample was 1.30 × 10-5 A/cm2 immediately after immersion in 3.5% NaCl solution, compared to 6.54 × 10-5 A/cm2 for the uncoated sample. X-ray photoelectron spectrometry results indicate that the formation of Al2O3 film contributes to the increased corrosion resistance of Al coating. Meanwhile, electrochemical impedance spectroscopy with equivalent electrical circuit was used to ascertain the corrosion process of the Al coatings. Results show the corrosion procedure consists of two stages which agree with the potentiodynamic polarization test. It can be concluded that the Al coating deposited by the D-gun spray process can improve the corrosion resistance of sintered NdFeB.

  9. High stress abrasive wear behavior of some hardfaced surfaces produced by thermal spraying

    NASA Astrophysics Data System (ADS)

    Jha, A. K.; Gachake, Arati; Prasad, B. K.; Dasgupta, Rupa; Singh, M.; Yegneswaran, A. H.

    2002-02-01

    Steel surfaces were thermally sprayed with nickel chromium boron (NCB) powder (with and without tungsten carbide) using an oxy-acetylene torch. The sprayed (hard) surfaces and substrate were characterized for abrasive wear properties. Test parameters such as load and sliding distance were varied. A significant improvement in the abrasive wear resistance (inverse of wear rate) was noted for the thermally sprayed surfaces as compared to that of the substrate. Wear surfaces, subsurface regions, and debris were examined in order to ascertain the operating wear mechanisms. Substrate (mild steel), because of its low hardness, suffered severe wear through the cutting, ploughing, and wedging action of the hard abrasive (silicon carbide). Deep cuts on the worn surface, a bulky transfer layer, subsurface cracks, and large-size debris were observed. However, wear was reduced due to high hardness of the layer of NCB powder on the substrate, which resisted the penetration of abrasive into the surface. Presence of tungsten carbide in the layer of NCB powder further reduced the wear of the corresponding specimen because of very high hardness of the tungsten carbide. Shallow wear grooves and finer debris were observed for the NCB coating with and without tungsten carbide. Cutting was the predominating wear mechanism in the case of coatings.

  10. Gas and drop behavior in reacting and non-reacting air-blast atomizer sprays

    NASA Technical Reports Server (NTRS)

    Mcdonell, Vincent G.; Samuelsen, Scott

    1991-01-01

    A detailed study of the two-phase flow produced by a gas-turbine air-blast atomizer is performed with the goal of identifying the interaction between the two phases for both nonreacting and reacting conditions. A two-component phase Doppler interferometry is utilized to characterize three flowfields produced by the atomizer: (1) the single-phase flow, (2) the two-phase nonreacting spray, and (3) the two-phase reacting spray. Measurements of the mean and fluctuating axial and azimuthal velocities for each phase are obtained. In addition, the droplet size distribution, volume flux, and concentration are measured. The results reveal the strong influence of the dispersed phase on the gas, and the influence of reaction on both the gas and the droplet field. The presence of the spray significantly alters the inlet condition of the atomizer. With this alteration quantified, it is possible to deduce that the inertia associated with the dispersed phase damps the fluctuating velocities of the gas. Reaction reduces the volume flux of the droplets, broadens the local volume distribution of the droplets in the region of the reaction zone, increases the axial velocities and radial spread of the gas, and increases the anisotropy in the region of the reaction zone.

  11. Gas and drop behavior in reacting and non-reacting air-blast atomizer sprays

    NASA Astrophysics Data System (ADS)

    McDonell, Vincent G.; Samuelsen, Scott

    1991-10-01

    A detailed study of the two-phase flow produced by a gas-turbine air-blast atomizer is performed with the goal of identifying the interaction between the two phases for both nonreacting and reacting conditions. A two-component phase Doppler interferometry is utilized to characterize three flowfields produced by the atomizer: (1) the single-phase flow, (2) the two-phase nonreacting spray, and (3) the two-phase reacting spray. Measurements of the mean and fluctuating axial and azimuthal velocities for each phase are obtained. In addition, the droplet size distribution, volume flux, and concentration are measured. The results reveal the strong influence of the dispersed phase on the gas, and the influence of reaction on both the gas and the droplet field. The presence of the spray significantly alters the inlet condition of the atomizer. With this alteration quantified, it is possible to deduce that the inertia associated with the dispersed phase damps the fluctuating velocities of the gas. Reaction reduces the volume flux of the droplets, broadens the local volume distribution of the droplets in the region of the reaction zone, increases the axial velocities and radial spread of the gas, and increases the anisotropy in the region of the reaction zone.

  12. Cooling cows efficiently with water spray: Behavioral, physiological, and production responses to sprinklers at the feed bunk.

    PubMed

    Chen, Jennifer M; Schütz, Karin E; Tucker, Cassandra B

    2016-06-01

    Dairies commonly mount nozzles above the feed bunk that intermittently spray cows to dissipate heat. These sprinklers use potable water-an increasingly scarce resource-but there is little experimental evidence for how much is needed to cool cows in loose housing. Sprinkler flow rate may affect the efficacy of heat abatement, cattle avoidance of spray (particularly on the head), and water waste. Our objectives were to determine how sprinkler flow rate affects cattle behavioral, physiological, and production responses when cows are given 24-h access to spray in freestall housing, and to evaluate heat abatement in relation to water use. We compared 3 treatments: sprinklers that delivered 1.3 or 4.9L/min (both 3min on and 9min off, 24h/d) and an unsprayed control. Nine pairs of high-producing lactating Holstein cows received each treatment at a shaded feed bunk for 2d in a replicated 3×3 Latin square design [air temperature (T): 24-h maximum=33±3°C, mean ± SD]. Cows spent 5.8±0.9h/24h (mean ± SD) at the feed bunk overall, regardless of treatment. With few exceptions, cows responded similarly to the 1.3 and 4.9L/min flow rates. Sprinklers resulted in visits to the feed bunk that were on average 23 to 27% longer and 13 to 16% less frequent compared with the control, perhaps because cows avoided walking through spray. Indeed, when the sprinklers were on, cows left the feed bunk half as often as expected by chance, and when cows chose to walk through spray, they lowered their heads on average 1.7- to 3-fold more often than in the control. Despite possible reluctance to expose their heads to spray, cows did not avoid sprinklers overall. In warmer weather, cows spent more time at the feed bunk when it had sprinklers (on average 19 to 21min/24h for each 1°C increase in T), likely for heat abatement benefits. Compared with the control, sprinklers resulted in 0.3 to 0.7°C lower body temperature from 1300 to 1500h and 1700 to 2000h overall and attenuated the rise in this

  13. Oxidation behavior of nanostructured cobalt nickel chromium aluminum yttrium and nickel cobalt chromium aluminum yttrium sprayed by HVOF

    NASA Astrophysics Data System (ADS)

    Mercier, Dominic

    In recent years, much development has been made in the world of nanotechnologies. Hence, nanomaterials, which possess unique characteristics and excellent mechanical properties, are now being used in innovative and advanced applications. Despite the incredible potential of nanomaterials, their use is still at an embryonic stage as a result of the difficulty to mass-produce them. Among the potentially viable application remains the fabrication of nanostructured powders to produce high temperature oxidation resistance coatings. Nanostructured coatings were obtained by thermally spraying cryomilled CoNiCrAlY and NiCoCrAlY feedstock using the HVOF technique. It was found that the milling process used to prepare the powder significantly altered the microstructure of the alloy. In addition to achieving grain size refinement, significant aluminum segregation at grain boundaries was observed. Upon oxidation experiments up to 96 hours in static air at 1000°C an oxide scale composed of an adherent and dense alpha-Al2O3 inner layer with a top layer of fast growing oxides such as NiO, Cr2O3, CoAl2O4 and NiAl2O4 evolved from the coatings. It was found that the formation of a two-layer scale could be prevented through surface grinding prior to oxidation. Moreover, the comparison of the oxidation results of the powders and those of the coatings revealed that the spraying process has a considerable influence on the oxidation behavior of MCrAlYs attributable to the formation of oxide seeds during the spraying process.

  14. Investigation of the Changes in Aerosolization Behavior Between the Jet-Milled and Spray-Dried Colistin Powders Through Surface Energy Characterization.

    PubMed

    Jong, Teresa; Li, Jian; Morton, David A V; Zhou, Qi Tony; Larson, Ian

    2016-03-01

    This study aimed to investigate the surface energy factors behind improved aerosolization performance of spray-dried colistin powder formulations compared with those produced by jet milling. Inhalable colistin powder formulations were produced by jet milling or spray drying (with or without l-leucine). Scanning electron micrographs showed the jet-milled particles had irregularly angular shapes, whereas the spray-dried particles were more spherical. Significantly higher fine particle fractions were measured for the spray-dried (43.8%-49.6%) versus the jet-milled formulation (28.4%) from a Rotahaler at 60 L/min; albeit the size distribution of the jet-milled powder was smaller. Surprisingly, addition of l-leucine in the spray drying feed solution gave no significant improvement in fine particle fraction. As measured by inverse gas chromatography, spray-dried formulations had significantly (p < 0.001) lower dispersive, specific, and total surface energy values and more uniform surface energy distributions than the jet-milled powder. Interestingly, no significant difference was measured in the specific and total surface energy values between the spray-dried formulation with or without l-leucine. Based on our previous findings in the self-assembling behavior of colistin in aqueous solution and the surface energy data obtained here, we propose the self-assembly of colistin molecules during spray drying contributed significantly to the reduction of surface free energy and the superior aerosolization performance. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  15. Anomalous dissolution behavior of celecoxib in PVP/Isomalt solid dispersions prepared using spray drier.

    PubMed

    Ghanavati, Roya; Taheri, Azade; Homayouni, Alireza

    2017-03-01

    Celecoxib is a COX II inhibitor NSAID which is used for joint pains, rheumatoid arthritis and osteoarthritis, however due to its poor water solubility it shows very low oral bioavailability. Using solid dispersion formulations is one of the most promising strategies to increase solubility of poorly water soluble drugs. The purpose of this study is dissolution enhancement of celecoxib by preparation of solid dispersions via spray drying technique using PVP and Isomalt as hydrophilic carriers. Different ratios of celecoxib, Isomalt and PVP K30 (7:3:0, 5:5:0, 3:7:0, 1:9:0 and 3:5:2, 3:2:5) were prepared from 2% hydroalcoholic solutions (70:30 ethanol:water) using spray drier. Particle size analyzing, saturation solubility, SEM, DSC, FT-IR, XRPD and dissolution studies in 0.25% SDS and 0.04M Na3HPO4 mediums were performed. Stability of samples was also studied after a week and a month storage at 75% humidity condition. The results showed that the saturation solubility of celecoxib in solid dispersion samples is 20-30 folds higher than raw celecoxib. Similar results have been shown for dissolution studies. Solid state analyses showed glass solution state of celecoxib in PVP/Isomalt matrixes. FTIR studies exhibited the formation of hydrogen bonding between celecoxib and PVP in these samples. Spray dried celecoxib (amorphous celecoxib) without usage of carrier showed lower dissolution rate compare to its crystalline state (in 0.25% SDS dissolution medium) whilst these results is vise versa in Na3PO4 dissolution medium. Interestingly almost all samples exhibited higher dissolution rate (in 0.25% SDS) after storage in 75% humidity. XRPD analysis demonstrated the crystallization of amorphous celecoxib after 1month storage. In general using PVP K30 and Isomalt as hydrophilic carriers could increase solubility and dissolution rate of celecoxib in solid dispersion formulations.

  16. Study of Traverse Speed Effects on Residual Stress State and Cavitation Erosion Behavior of Arc-Sprayed Aluminum Bronze Coatings

    NASA Astrophysics Data System (ADS)

    Hauer, Michél; Henkel, Knuth Michael; Krebs, Sebastian; Kroemmer, Werner

    2017-01-01

    Within a research project regarding cavitation erosion-resistant coatings, arc spraying was used with different traverse speeds to influence heat transfer and the resulting residual stress state. The major reason for this study is the lack of knowledge concerning the influence of residual stress distribution on mechanical properties and coating adhesion, especially with respect to heterogeneous aluminum bronze alloys. The materials used for spray experiments were the highly cavitation erosion-resistant propeller alloys CuAl9Ni5Fe4Mn (Ni-Al-Bronze) and CuMn13Al8Fe3Ni2 (Mn-Al-Bronze). Analyses of cavitation erosion behavior were carried out to evaluate the suitability for use in marine environments. Further microstructural, chemical and mechanical analyses were realized to examine adhesive and cohesive coating properties. Residual stress distribution was measured by modified hole drilling method using electronic speckle pattern interferometry (ESPI). It was found that the highest traverse speed led to higher tensile residual stresses near the surface and less cavitation erosion resistance of the coatings. Moreover, high oxygen affinity of main alloying element aluminum was identified to severely influence the microstructures by the formation of large oxides and hence the coating properties. Overall, Mn-Al-Bronze coatings showed lower residual stresses, a more homogeneous pore and oxide distribution and less material loss by cavitation than Ni-Al-Bronze coatings.

  17. Tensile deformation behavior of spray-deposited FVS0812 heat-resistant aluminum alloy sheet at elevated temperatures

    SciTech Connect

    Yan Qiqi; Fu Dingfa . E-mail: Fudingfa69@163.com; Deng Xuefeng; Zhang Hui; Chen Zhenhua

    2007-06-15

    The tensile deformation behavior of spray deposited FVS0812 heat-resistant aluminum alloy sheet was studied by uniaxial tension tests at temperatures ranging from 250 deg. C to 450 deg. C and strain rates from 0.001 to 0.1 s{sup -1}. The associated fracture surfaces were examined by scanning electron microscopy (SEM). The results show that the degree of work-hardening increases with decreasing temperature, and exhibits a small decrease with increasing strain rate; the strain rate sensitivity exponent increases with increasing temperature. The flow stress increases with increasing strain rate but decreases with increasing temperature. The total elongations to fracture increase not only with increasing temperature, but also with increasing strain rate, which is in marked contrast with the normal inverse dependence of elongation on the strain rate exhibited by conventional aluminum alloy sheets. The SEM fracture analysis indicates that the dependence of elongation on the strain rate may be due to the presence of a transition from plastic instability at lower strain rates to stable deformation at higher strain rates for fine-grained materials produced by spray deposition.

  18. Computational study and experimental comparison of the in-flight particle behavior for an external injection plasma spray process

    NASA Astrophysics Data System (ADS)

    Remesh, K.; Yu, S. C. M.; Ng, H. W.; Berndt, C. C.

    2003-12-01

    A three-dimensional computational fluid dynamic (CFD) analysis using Fluent V5.4 was conducted on the in-flight particle behavior during the plasma spraying process with external injection. The spray process was modeled as a steady jet issuing from the torch nozzle via the heating of the are gas by an electric are within the nozzle. The stochastic discrete model was used for the particle distribution. The particle temperature, velocity, and size inside the plasma plume at a specified standoff distance have been investigated. The results show that carrier gas flow rate variation from 2 standard liters per minute (slm) to 4.0 slm can increase the centerline particle mean temperature and mean velocity by 10% and 16%, respectively, at the specified standoff distance. A further increase of the carrier gas flow rate to 6 slm did not change the particle temperature, but the particle velocity was decreased by 20%. It was also found that an increase in the total arc gas flow rate from 52 slm to 61 slm, with all other process parameters unchanged, resulted in a 17% higher particle velocity, but 6% lower particle temperature. Some of these computational findings were experimentally confirmed by Kucuk et al. For a given process parameter setting, the kinetic and thermal energy extracted by the particles reached a maximum for carrier gas flow rate of about 3.5 4.0 slm.

  19. Microstructure, excess solid solubility, and elevated-temperature mechanical behavior of spray-atomized and codeposited Al-Ti-SiCP

    NASA Astrophysics Data System (ADS)

    Gupta, M.; Juarez-Islas, J.; Frazier, W. E.; Mohamed, F. A.; Lavernia, E. J.

    1992-12-01

    In the present study, the microstructure, thermal stability, and elevated temperature mechanical behavior of Al-Ti-SiCP metal matrix composites (MMCs) processed by spray atomization and codeposition were investigated. The evolution of the microstructure of the spray-deposited material before and after thermal annealing was studied using X-ray diffractometry, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and optical microscopy. The thermal stability of the spray-deposited materials was determined by monitoring the changes in hardness after isochronal thermal anneals at various temperatures. The results of X-ray and microanalysis studies revealed the presence of a supersaturated solid solution of Ti in α Al in the spray-atomized and codeposited material, with Ti concentrations in the 0.8 to 1.1 wt pet range. The formation of an extended solid solution was discussed in light of the cooling rates present during atomization and, subsequently, during deposition. Regarding mechanical behavior, the present results suggest that the as-spray deposited and hot extruded Al-Ti matrix is thermally stable up to a temperature of 400 °C and that the excess solid solubility of Ti in a Al, resulting from the rapid quench during processing, is maintained up to a temperature of 300 °C. The elevated-temperature mechanical properties of the hot extruded spray-deposited materials were studied following a 100-hour exposure at 250 °C, 350 °C, and 450 °C; the roomtemperature mechanical properties were also determined. Results show that the elevated-temperature yield strength of the spray-deposited and extruded materials compared favorably to those of an equivalent alloy made by powder metallurgical materials, were superior to those of the ingot material, but were inferior to those of mechanically alloyed Al-Ti materials. In addition, TEM studies showed no evidence of interfacial reactions at the Al-Ti/SiCP interface.

  20. Electrochemical Impedance Studies on Tribocorrosion Behavior of Plasma-Sprayed Al2O3 Coatings

    NASA Astrophysics Data System (ADS)

    Liu, Zhe; Chu, Zhenhua; Chen, Xueguang; Dong, Yanchun; Yang, Yong; Li, Yingzhen; Yan, Dianran

    2015-06-01

    In this paper, the tribocorrosion of plasma-sprayed Al2O3 coatings in simulated seawater was investigated by electrochemical impedance spectroscopy (EIS) technique, complemented by scanning electron microscopy to observe the morphology of the tribocorrosion attack. Base on EIS of plasma-sprayed Al2O3 coatings undergoing long-time immersion in simulated seawater, the corrosion process of Al2O3 coatings can be divided into the earlier stage of immersion (up to 20 h) and the later stage (beyond 20 h). Then, the wear tests were carried out on the surface of Al2O3 coating undergoing different times of immersion to investigate the influence of wear on corrosion at different stages. The coexistence of wear and corrosion condition had been created by a boron nitride grinding head rotating on the surface of coatings corroded in simulated seawater. The measured EIS and the values of the fitting circuit elements showed that wear accelerated corrosion at the later stage, meanwhile, corrosion accelerated wear with the immersion time increasing.

  1. Hot Corrosion Behavior of HVOF Sprayed Coatings on ASTM SA213-T11 Steel

    NASA Astrophysics Data System (ADS)

    Sidhu, H. S.; Sidhu, B. S.; Prakash, S.

    2007-09-01

    Cr3C2-NiCr, NiCr, WC-Co and Stellite-6 alloy coatings were sprayed on ASTM SA213-T11 steel using the HVOF process. Liquid petroleum gas was used as the fuel gas. Hot corrosion studies were conducted on the uncoated as well as HVOF sprayed specimens after exposure to molten salt at 900 °C under cyclic conditions. The thermo-gravimetric technique was used to establish the kinetics of corrosion. XRD, SEM/EDAX and EPMA techniques were used to analyze the corrosion products. All these overlay coatings showed a better resistance to hot corrosion as compared to that of uncoated steel. NiCr Coating was found to be most protective followed by the Cr3C2-NiCr coating. WC-Co coating was least effective to protect the substrate steel. It is concluded that the formation of Cr2O3, NiO, NiCr2O4, and CoO in the coatings may contribute to the development of a better hot-corrosion resistance. The uncoated steel suffered corrosion in the form of intense spalling and peeling of the scale, which may be due to the formation of unprotective Fe2O3 oxide scale.

  2. Fabrication and Wear Behavior of Nanostructured Plasma-Sprayed 6061Al-SiCp Composite Coating

    NASA Astrophysics Data System (ADS)

    Tailor, Satish; Mohanty, R. M.; Sharma, V. K.; Soni, P. R.

    2014-10-01

    6061Al powder with 15 wt.% SiC particulate (SiCp) reinforcement was mechanically alloyed (MA) in a high-energy attrition mill. The MA powder was then plasma sprayed onto weathering steel (Cor-Ten A242) substrate using an atmospheric plasma spray process. Results of particle size analysis and scanning electron microscopy show that the addition of SiC particles as the reinforcement influences on the matrix grain size and morphology. XRD studies revealed embedment of SiCp in the MA-processed composite powder, and nanocrystals in the MA powder and the coating. Microstructural studies showed a uniform distribution of reinforced SiC particles in the coating. The porosity level in the coating was as low as 2% while the coating hardness was increased to 232VHN. The adhesion strength of the coatings was high and this was attributed to higher degree of diffusion at the interface. The wear rate in the coatings was evaluated using a pin-on-disk type tribometer and found to decrease by 50% compared to the 6061Al matrix coating. The wear mechanism in the coating was delamination and oxidative type.

  3. Cyclic delamination behavior of plasma-sprayed hydroxyapatite coating on Ti-6Al-4V substrates in simulated body fluid.

    PubMed

    Otsuka, Yuichi; Kawaguchi, Hayato; Mutoh, Yoshiharu

    2016-10-01

    This study aimed to clarify the effect of a simulated body fluid (SBF) on the cyclic delamination behavior of a plasma-sprayed hydroxapatite (HAp) coating. A HAp coating is deposited on the surfaces of surgical metallic materials in order to enhance the bond between human bone and such surfaces. However, the HAp coating is susceptible to delamination by cyclic loading from the patient's gait. Although hip joints are subjected to both positive and negative moments, only the effects of tensile bending stresses on vertical crack propagation behavior have been investigated. Thus, the cyclic delamination behavior of a HAp coating was observed at the stress ratio R=-1 in order to determine the effects of tensile/compressive loading on the delamination behavior. The delamination growth rate increased with SBF immersion, which decreased the delamination life. Raman spectroscopy analysis revealed that the selective phase dissolution in the HAp coating was promoted at interfaces. Finite element analysis revealed that the energy release rate Gmax showed a positive value even in cases with compressive loading, which is a driving force for the delamination of a HAp coating. A prediction model for the delamination growth life was developed that combines a fracture mechanics parameter with the assumed stress-dependent dissolution rate. The predicted delamination life matched the experimental data well in cases of lower stress amplitudes with SBF.

  4. High-temperature frictional wear behavior of MCrAlY-based coatings deposited by atmosphere plasma spraying

    NASA Astrophysics Data System (ADS)

    Tao, Chong; Wang, Lei; Song, Xiu

    2017-02-01

    Al2O3-Cr2O3/NiCoCrAlYTa coatings were prepared via atmosphere plasma spraying (APS). The microstructure and phase composition of the coatings were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), laser confocal scanning microscopy (LSCM), and transmission electron microscopy (TEM). The dry frictional wear behavior of the coatings at 500°C in static air was investigated and compared with that of 0Cr25Ni20 steel. The results show that the coatings comprise the slatted layers of oxide phases, unmelted particles, and pores. The hot abrasive resistance of the coatings is enhanced compared to that of 0Cr25Ni20, and their mass loss is approximately one-fifteenth that of 0Cr25Ni20 steel. The main wear failure mechanisms of the coatings are abrasive wear, fatigue wear, and adhesive wear.

  5. Investigation on the Tribological Behavior of Arc-Sprayed and Hammer-Peened Coatings Using Tungsten Carbide Cored Wires

    NASA Astrophysics Data System (ADS)

    Tillmann, W.; Hagen, L.; Schröder, P.

    2017-01-01

    Due to their outstanding properties, WC-W2C iron-based cermet coatings are widely used in the field of wear protection. Regarding commonly used WC-W2C reinforced coating systems, it has been reported that their tribological behavior is mainly determined by the carbide grain size fraction. Although the manufacturing route for arc-sprayed WC-W2C cermet coatings is in an advanced state, there is still a lack of knowledge concerning the performance of cored wires with tungsten carbides as filling material and their related coating properties when post-treatment processes are used such as machine hammer peening (MHP). A major objective was to characterize WC-W2C FeCMnSi coatings, deposited with different carbide grain size fractions as a filling using cored wires, with respect to their tribological behavior. Moreover, deposits derived from cored wires with a different amount of hard phases are investigated. According to this, polished MHP surfaces are compared to as-sprayed and polished samples by means of metallographic investigations. With the use of ball-on-disk and dry rubber wheel tests, dry sliding and rolling wear effects on a microscopic level are scrutinized. It has been shown that the MHP process leads to a densification of the microstructure formation. For dry sliding experiments, the MHP coatings obtain lower wear resistances, but lower coefficients of friction than the conventional coatings. In view of abrasion tests, the MHP coatings possess an improved wear resistance. Strain hardening effects at the subsurface area were revealed by the mechanical response using nanoindentation. However, the MHP process has caused a cracking of embedded carbides, which favor breakouts, leading to advanced third-body wear.

  6. Effects of detailed droplet heating models on turbulent sprays vaporization behavior

    NASA Technical Reports Server (NTRS)

    Mawid, M. A.

    1993-01-01

    The effects of three different droplet heating models on the vaporization history and internal structure of turbulent liquid fuel sprays were investigated. The models considered were the infinite-diffusion, diffusion-limit, and effective-conductivity models. A numerical solution for the models was developed and implemented in the KIVA-II computer code. Low temperature and relatively high temperature numerical studies were conducted. The low temperature computations were compared with existing experimental data. The comparisons showed that while the infinite-diffusion and diffusion-limit models respectively overpredicted and underpredicted the fuel vapor peak concentration and distribution in the combustor, the effective-conductivity model gave results that were in better agreement with measurements. A limited study for the high temperature case was performed due to lack of experimental data and predictions using the three models were compared with each other.

  7. Hot Corrosion Resistance and Mechanical Behavior of Atmospheric Plasma Sprayed Conventional and Nanostructured Zirconia Coatings

    NASA Astrophysics Data System (ADS)

    Saremi, Mohsen; Keyvani, Ahmad; Heydarzadeh Sohi, Mahmoud

    Conventional and nanostructured zirconia coatings were deposited on In-738 Ni super alloy by atmospheric plasma spray technique. The hot corrosion resistance of the coatings was measured at 1050°C using an atmospheric electrical furnace and a fused mixture of vanadium pent oxide and sodium sulfate respectively. According to the experimental results nanostructured coatings showed a better hot corrosion resistance than conventional ones. The improved hot corrosion resistance could be explained by the change of structure to a dense and more packed structure in the nanocoating. The evaluation of mechanical properties by nano indentation method showed the hardness (H) and elastic modulus (E) of the YSZ coating increased substantially after hot corrosion.

  8. Effect of cold spray deposition of a titanium coating on fatigue behavior of a titanium alloy

    NASA Astrophysics Data System (ADS)

    Price, T. S.; Shipway, P. H.; McCartney, D. G.

    2006-12-01

    The deposition of titanium on a titanium alloy substrate is being examined for potential use as a surface treatment for medical prostheses. A Ti6Al4V alloy was coated with pure titanium by cold gas dynamic spraying. Coatings were deposited onto samples with two different surface preparation methods (as-received and grit-blasted). The fatigue life of the as-received and grit-blasted materials, both before and after coating, was measured with a rotating-bend fatigue rig. A 15% reduction in fatigue endurance limit was observed after application of the coating to the as-received substrate, but no significant reduction was observed on its application to the grit-blasted substrate. The reduction in fatigue endurance limit has been related to the substrate-coating interface properties, the elastic modulus, and the residual stress states.

  9. Cyclic Oxidation Behavior of CuCrAl Cold-Sprayed Coatings for Reusable Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Raj, Sai; Karthikeyan, J.

    2009-01-01

    The next generation of reusable launch vehicles is likely to use GRCop-84 [Cu-8(at.%)Cr-4%Nb] copper alloy combustion liners. The application of protective coatings on GRCop-84 liners can minimize or eliminate many of the environmental problems experienced by uncoated liners and significantly extend their operational lives and lower operational cost. A newly developed Cu- 23 (wt.%) Cr-5% Al (CuCrAl) coating, shown to resist hydrogen attack and oxidation in an as-cast form, is currently being considered as a protective coating for GRCop-84. The coating was deposited on GRCop-84 substrates by the cold spray deposition technique, where the CuCrAl was procured as gas-atomized powders. Cyclic oxidation tests were conducted between 773 and 1,073 K to characterize the coated substrates.

  10. Stable macroscopic quantum superpositions.

    PubMed

    Fröwis, F; Dür, W

    2011-03-18

    We study the stability of superpositions of macroscopically distinct quantum states under decoherence. We introduce a class of quantum states with entanglement features similar to Greenberger-Horne-Zeilinger (GHZ) states, but with an inherent stability against noise and decoherence. We show that in contrast to GHZ states, these so-called concatenated GHZ states remain multipartite entangled even for macroscopic numbers of particles and can be used for quantum metrology in noisy environments. We also propose a scalable experimental realization of these states using existing ion-trap setups.

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  12. A Micromechanics Finite Element Model for Studying the Mechanical Behavior of Spray-On Foam Insulation (SOFI)

    NASA Technical Reports Server (NTRS)

    Ghosn, Louis J.; Sullivan, Roy M.; Lerch, Bradley A.

    2006-01-01

    A micromechanics model has been constructed to study the mechanical behavior of spray-on foam insulation (SOFI) for the external tank. The model was constructed using finite elements representing the fundamental repeating unit of the SOFI microstructure. The details of the micromechanics model were based on cell observations and measured average cell dimensions discerned from photomicrographs. The unit cell model is an elongated Kelvin model (fourteen-sided polyhedron with 8 hexagonal and six quadrilateral faces), which will pack to a 100% density. The cell faces and cell edges are modeled using three-dimensional 20-node brick elements. Only one-eighth of the cell is modeled due to symmetry. By exercising the model and correlating the results with the macro-mechanical foam behavior obtained through material characterization testing, the intrinsic stiffness and Poisson s Ratio of the polymeric cell walls and edges are determined as a function of temperature. The model is then exercised to study the unique and complex temperature-dependent mechanical behavior as well as the fracture initiation and propagation at the microscopic unit cell level.

  13. Microstructure and Wear Behavior of Atmospheric Plasma-Sprayed AlCoCrFeNiTi High-Entropy Alloy Coating

    NASA Astrophysics Data System (ADS)

    Tian, Li-Hui; Xiong, Wei; Liu, Chuan; Lu, Sheng; Fu, Ming

    2016-12-01

    Due to the advantages such as high strength, high hardness and good wear resistance, high-entropy alloys (HEAs) attracted more and more attentions in recent decades. However, most reports on HEAs were limited to bulk materials. Although a few of studies on atmospheric plasma-sprayed (APS) HEA coatings were carried out, the wear behavior, especially the high-temperature wear behavior of those coatings has not been investigated till now. Therefore, in this study, APS was employed to deposit AlCoCrFeNiTi high-entropy alloy coating using mechanically alloyed AlCoCrFeNiTi powder as the feedstock. The phase structure of the initial powder, the feedstock powder and the as-sprayed coating was examined by an x-ray diffractometer. The surface morphology of the feedstock powder and the microstructure of the as-sprayed coating were analyzed by field emission scanning electron microscopy and energy-dispersive spectroscopy. The bonding strength and the microhardness of the as-sprayed coating were tested. The wear behavior of the coating at 25, 500, 700 and 900 °C was investigated by analysis of the wear surface morphology and measurements of the volume wear rate and the coefficient of friction.

  14. Microstructural Characterization and Wear Behavior of Nano-Boride Dispersed Coating on AISI 304 Stainless Steel by Hybrid High Velocity Oxy-Fuel Spraying Laser Surface Melting

    NASA Astrophysics Data System (ADS)

    Sharma, Prashant; Majumdar, Jyotsna Dutta

    2015-07-01

    The current study concerns the detailed microstructural characterization and investigation of wear behavior of nano-boride dispersed coating developed on AISI 304 stainless steel by high velocity oxy-fuel spray deposition of nickel-based alloy and subsequent laser melting. There is a significant refinement and homogenization of microstructure with improvement in microhardness due to laser surface melting (1200 VHN as compared to 945 VHN of as-sprayed and 250 VHN of as-received substrate). The high temperature phase stability of the as-coated and laser melted surface has been studied by differential scanning calorimeter followed by detailed phase analysis at room and elevated temperature. There is a significant improvement in wear resistance of laser melted surface as compared to as-sprayed and the as-received one due to increased hardness and reduced coefficient of friction. The mechanism of wear has been investigated in details. Corrosion resistance of the coating in a 3.56 wt pct NaCl solution is significantly improved (4.43 E-2 mm/year as compared to 5 E-1 mm/year of as-sprayed and 1.66 mm/year of as-received substrate) due to laser surface melting as compared to as-sprayed surface.

  15. Sintering and Creep Behavior of Plasma-Sprayed Zirconia and Hafnia Based Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    1998-01-01

    The sintering and creep of plasma-sprayed ceramic thermal barrier coatings under high temperature conditions are complex phenomena. Changes in thermomechanical and thermophysical properties and in the stress response of these coating systems as a result of the sintering and creep processes are detrimental to coating thermal fatigue resistance and performance. In this paper, the sintering characteristics of ZrO2-8wt%y2O3, ZrO2-25wt%CeO2-2.5wt%Y2O3, ZrO2-6w%NiO- 9wt%Y2O3, ZrO2-6wt%Sc2O3-2wt%y2O3 and HfO2-27wt%y2O3 coating materials were investigated using dilatometry. It was found that the HfO2-Y2O3 and baseline ZrO2-Y2O3 exhibited the best sintering resistance, while the NiO-doped ZrO2-Y2O3 showed the highest shrinkage strain rates during the tests. Higher shrinkage strain rates of the coating materials were also observed when the specimens were tested in Ar+5%H2 as compared to in air. This phenomenon was attributed to an enhanced metal cation interstitial diffusion mechanism under the reducing conditions. It is proposed that increased chemical stability of coating materials will improve the material sintering resistance.

  16. High Temperature Oxidation Behavior of HVOF-sprayed Coatings for Use in Thixoextrusion Processes

    SciTech Connect

    Picas, J. A.; Punset, M.; Menargues, S.; Campillo, M.; Baile, M. T.; Forn, A.

    2011-05-04

    The dies used for the thixoextrusion of steels have to be capable of withstanding complex thermal and mechanical loads, while giving a sufficient wear resistance against abrasion and adhesion at very high temperatures. In order to improve the wear resistance and reduce the heating of the extrusion die it can be protected with a hard cermet coating. The purpose of this work is to study the high-temperature performance of CrC-CoNiCrAlY coating and explore the potential application of this coating to improve dies used in thixoextrusion processes. A two-layer 75CrC-25CoNiCrAlY coating with a CoNiCrAlY bond-coating was fabricated by the HVOF thermal spray process on a steel substrate. Coatings were heat-treated at a range of temperatures between 900 deg. C and 1100 deg. C. The microstructural characterization of the coatings before and after heat treatment was conducted by scanning electron microscopy (SEM) and an X-ray diffractometer (XRD). The mechanical properties of coatings were determined as a function of the temperature of heat treatment. The bond coat effect on the thermal shock resistance of CrC-CoNiCrAlY coating was analyzed.

  17. Corrosion Behavior of HVOF-Sprayed Fe-Based Alloy Coating in Various Solutions

    NASA Astrophysics Data System (ADS)

    Qiao, Lei; Wu, Yuping; Hong, Sheng; Qin, Yujiao; Shi, Wei; Li, Gaiye

    2017-08-01

    A Fe-based amorphous/nanocrystalline coating was prepared by the high-velocity oxygen fuel (HVOF) spraying process. The coating was characterized by x-ray diffraction, scanning electron microscopy and transmission electron microscopy. The corrosion resistances of the Fe-based coating and a reference electroplated hard chromium (EHC) coating were evaluated in a 3.5% NaCl solution, a 1 mol/L HCl solution and a 1 mol/L NaOH solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). All of the results indicated that the corrosion resistance of the Fe-based coating was superior to the resistance of the EHC coating in both the 3.5% NaCl solution and the 1 mol/L HCl solution due to the dense structure and fewer defects of the Fe-based coating. However, the corrosion resistance of the Fe-based coating was inferior to corrosion resistance of the EHC coating in the 1 mol/L NaOH solution. This could be ascribed to the drastic passivation of the EHC coating in an alkaline environment.

  18. Heat load behaviors of plasma sprayed tungsten coatings on copper alloys with different compliant layers

    NASA Astrophysics Data System (ADS)

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

    2008-04-01

    Plasma sprayed tungsten (PS-W) coatings with the compliant layers of titanium (Ti), nickel-chromium-aluminum (NiCrAl) alloys and W/Cu mixtures were fabricated on copper alloys, and their properties of the porosity, oxygen content, thermal conductivity and bonding strength were measured. High heat flux tests of actively cooled W coatings were performed by means of an electron beam facility. The results indicated that APS-W coating showed a poorer heat transfer capability and thermo-mechanical properties than VPS-W coating, and the compliant layers improved W coating performance under the heat flux load. Among three compliant layers, W/Cu was the preferable because of its better effects on heat removal and stress alleviating. The optimization of W/Cu compliant layer found that 0.1 mm and 25 vol.%W was optimum compliant layer structure for 1 mm W coating, which induced a 23% reduction of the maximum stress compared to the sharp interface, and the plastic strain was reduced to 0.01% from 1.55%.

  19. Wear and Friction Behavior of the Spray-Deposited SiCp/Al-20Si-3Cu Functionally Graded Material

    NASA Astrophysics Data System (ADS)

    Su, B.; Yan, H. G.; Chen, J. H.; Zeng, P. L.; Chen, G.; Chen, C. C.

    2013-05-01

    The spray-deposited SiCp/Al-20Si-3Cu functionally graded material (FGM) can meet the structure design requirements of brake disk. The effects of rotational speed and load on the wear and friction behaviors of the SiCp/Al-20Si-3Cu FGM sliding against the resin matrix friction material were investigated. For comparison, the wear and friction behaviors of a commercially used cast iron (HT250) brake rotor were also studied. The results indicate that the friction coefficient of the SiCp/Al-20Si-3Cu FGM decreases constantly with the increase of load or rotational speed and is affected by the gradient distribution of SiC particles. The wear rate of the SiCp/Al-20Si-3Cu FGM firstly increases, then decreases and finally increases again with increasing load or speed, and is about 1/10 of that of HT250. Based on observations and analyses on the morphology and substructure of the worn surface, the mechanical mixing layer acts as a protective coating and lubricant, and its thickness reduces with the SiC content increasing. Furthermore, it is proposed that the dominant wear mechanism of SiCp/Al-20Si-3Cu FGM changes from the abrasive wear to the oxidative wear and further to the delamination wear with increasing load or speed.

  20. Supercritical (and Subcritical) Fluid Behavior and Modeling: Drops, Streams, Shear and Mixing Layers, Jets and Sprays

    NASA Technical Reports Server (NTRS)

    Bellan, J.

    1999-01-01

    A critical review of recent investigations in the real of supercritical (and subcritical) fluid behavior is presented with the goal of obtaining a perspective on the peculiarities of high pressure observations.

  1. In-flight behavior of dissimilar co-injected particles in the spraying of metal-ceramic functionally gradient materials

    SciTech Connect

    Fincke, J.R.; Swank, W.D.; Haggard, D.C.

    1997-12-31

    In the spraying of functionally gradient coatings the particle ensemble delivered to the substrate can vary from a relatively low melting point metallic particle to a significantly higher melting point ceramic particle. At various stages in the spray process the particle ensemble can be either predominantly metallic, ceramic, or an intermediate combination. For co-injected particles the mixtures do not behave as a simple linear superposition of the spray patterns of the individual particle types. The particle temperature, velocity, size distributions, and pattern characteristics of the resulting spray fields is examined for all ceramic particle sprays (ZrO{sub 2}), all metallic particle sprays (NiCrAlY), and for a 1:1 mixture. The major particle-particle interaction occurs in the injector itself and results in a modified spray pattern which is different from that of either material sprayed alone. The particle velocity distributions generally exhibit a bimodal nature which is dependent on the size and density of the injected particles.

  2. Influence of laser on the droplet behavior in short-circuiting, globular, and spray modes of hybrid fiber laser-MIG welding

    NASA Astrophysics Data System (ADS)

    Cai, Chuang; Feng, Jiecai; Li, Liqun; Chen, Yanbin

    2016-09-01

    The effects of laser on the droplet behavior in short-circuiting, globular, and spray modes of hybrid fiber laser-MIG welding were studied. Transfer sequence of a droplet, welding current wave and morphology of plasma in the three modes of arc welding and hybrid welding were comparatively investigated. Compared with arc welding, the transfer frequency and landing location of droplet in the three modes of hybrid welding changed. In short-circuiting and globular modes, the droplet transfer was promoted by the laser, while the droplet transfer was hindered by the laser in spray mode. The magnitudes and directions of electromagnetic force and plasma drag force acting on the droplet were the keys to affect the droplet behavior. The magnitudes and directions of electromagnetic force and plasma drag force were converted due to the variation of the current distribution into the droplet, which were caused by the laser induced plasma with low ionization potential.

  3. Impact of feed counterion addition and cyclone type on aerodynamic behavior of alginic-atenolol microparticles produced by spray drying.

    PubMed

    Ceschan, Nazareth Eliana; Bucalá, Verónica; Ramírez-Rigo, María Verónica; Smyth, Hugh David Charles

    2016-12-01

    The inhalatory route has emerged as an interesting non-invasive alternative for drug delivery. This allows both pulmonary (local) and systemic treatments (via alveolar absorption). Further advantages in terms of stability, dose and patient preference have often lead researchers to focus on dry powder inhaler delivery systems. Atenolol is an antihypertensive drug with low oral bioavailability and gastrointestinal side effects. Because atenolol possesses adequate permeation across human epithelial membranes, it has been proposed as a good candidate for inhalatory administration. In a previous work, atenolol was combined with alginic acid (AA) and microparticles were developed using spray-drying (SD) technology. Different AA/atenolol ratios, total feed solid content and operative variables were previously explored. In order to improve particle quality for inhalatory administration and the SD yield, in this work the AA acid groups not neutralized by atenolol were kept either free or neutralized to pH∼7 and two different SD cyclones were used. Particle morphology, flow properties, moisture uptake and in vitro aerosolization behavior at different pressure drops were studied. When the AA acid groups were neutralized, particle size decreased as a consequence of the lower feed viscosity. The SD yield and in vitro particle deposition significantly increased when a high performance cyclone was employed, and even when lactose carrier particles were not used. Although the in vitro particle deposition decreased when the storage relative humidity increased, the developed SD powders showed adequate characteristics to be administered by inhalatory route up to storage relative humidities of about 60%.

  4. Corrosion Behavior of Arc-Sprayed Zn-Al Coating in the Presence of Sulfate-Reducing Bacteria in Seawater

    NASA Astrophysics Data System (ADS)

    Hong, Sheng; Wu, Yuping; Gao, Wenwen; Zhang, Jianfeng; Qin, Yujiao

    2015-11-01

    Zn-Al coatings were prepared by high-velocity arc spraying process and were sealed by the silicone resin to improve their corrosion resistance. The corrosion behavior of the unsealed and sealed Zn-Al coatings in the presence of sulfate-reducing bacteria (SRB) in seawater was evaluated, and the related mechanism was discussed. The results showed that the charge transfer resistance value of the sealed coating was almost ten times higher than that of the unsealed coating, and the concentration of element S in the covering layer of the former was half lower than that of the latter. The corrosion resistance of the coating was apparently improved by the sealing treatment. The corrosion rate of the coatings first increased and then decreased during the immersion time of 8 days in the seawater with SRB. The removal of the passive films in the initial period was attributed to penetration of the corrosion medium into the coating and the dissolution of the active zones inside the coating. The adhesion of SRB and accumulation of corrosion products on the coating surface would protect the coating from being further damaged.

  5. Thermal-Cycling Behavior of Plasma-Sprayed Partially Stabilized Zirconia Coatings on High-Density Graphite Substrate

    NASA Astrophysics Data System (ADS)

    Sure, Jagadeesh; Thyagarajan, K.; Mallika, C.; Mudali, U. Kamachi

    2015-08-01

    The thermal cycling behavior of partially stabilized zirconia (PSZ)-coated by plasma-spray process on NiCrAlY bond-coated high-density (HD) graphite substrate was investigated. Thermal cycling was carried out at 600 and 750 °C under vacuum, up to 200 cycles. Each cycle comprised a 10-min heating followed by forced air cooling for 10 min down to room temperature. Characterization of the microstructure and the phase analysis of thermal-cycled PSZ coatings by scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction (XRD), and Raman spectroscopy revealed the correlation between the microstructural/crystallographic phases and the mechanical integrity of the coating up to 200 cycles. Segmented and vertical cracks generated on the coating during thermal cycling were observed to propagate with increase in the number of cycles. Macrocracks and variations in elemental compositions were not observed until 200 cycles at 600 and 750 °C. XRD and Raman spectroscopic analysis confirmed the presence of nontransformable tetragonal phase only in all the thermal-cycled PSZ coatings, irrespective of temperature up to 200 cycles.

  6. Thermal Shock and Ablation Behavior of Tungsten Nozzle Produced by Plasma Spray Forming and Hot Isostatic Pressing

    NASA Astrophysics Data System (ADS)

    Wang, Y. M.; Xiong, X.; Zhao, Z. W.; Xie, L.; Min, X. B.; Yan, J. H.; Xia, G. M.; Zheng, F.

    2015-08-01

    Tungsten nozzle was produced by plasma spray forming (PSF, relative density of 86 ± 2%) followed by hot isostatic pressing (HIPing, 97 ± 2%) at 2000 °C and 180 MPa for 180 min. Scanning electron microscope, x-ray diffractometer, Archimedes method, Vickers hardness, and tensile tests have been employed to study microstructure, phase composition, density, micro-hardness, and mechanical properties of the parts. Resistance of thermal shock and ablation behavior of W nozzle were investigated by hot-firing test on solid rocket motor (SRM). Comparing with PSF nozzle, less damage was observed for HIPed sample after SRM test. Linear ablation rate of nozzle made by PSF was (0.120 ± 0.048) mm/s, while that after HIPing reduced to (0.0075 ± 0.0025) mm/s. Three types of ablation mechanisms including mechanical erosion, thermophysical erosion, and thermochemical ablation took place during hot-firing test. The order of degree of ablation was nozzle throat > convergence > dilation inside W nozzle.

  7. Wear Behavior of Plasma-Sprayed Carbon Nanotube-Reinforced Aluminum Oxide Coating in Marine and High-Temperature Environments

    NASA Astrophysics Data System (ADS)

    Keshri, Anup Kumar; Agarwal, Arvind

    2011-12-01

    Wear behavior of plasma-sprayed carbon nanotube (CNT)-reinforced aluminum oxide (Al2O3) composite coatings are investigated at room temperature (298 K), elevated temperature (873 K), and in sea water. Lowest wear volume loss was observed in the sea water as compared to dry sliding at 298 and 873 K. Relative improvement in the wear resistance of Al2O3-8 wt.% CNT coating compared to Al2O3 was 72% at 298 K, 76% at 873 K, and 66% in sea water. The improvement in the wear resistance of Al2O3-CNT coatings is attributed to (i) larger area coverage by protective film on the wear surface at room temperature and in sea water, (ii) higher fracture toughness of Al2O3-CNT coatings due to CNT bridging between splats, and (iii) anti-friction effect of sea water. The average coefficient of friction (COF) was the lowest (0.55) in sea water and the highest (0.83) at 873 K for Al2O3-8 wt.% CNT coating.

  8. Influence of dopant on the behavior under thermal cycling of two plasma- sprayed zirconia coatings Part 2: residual stresses

    NASA Astrophysics Data System (ADS)

    Hamacha, R.; Fauchais, P.; Nardou, F.

    1997-06-01

    The evolution of coating morphology and surface residual stresses was followed for three different pow-ders: zirconia stabilized with 8 wt% yttria (YSZ), 9.9 wt% dysprosia (DSZ), and 9.8 wt% ytterbia (YbSZ). The YSZ reference powder was fused and crushed (-45 +22 μm), and the other two were agglom-erated and sintered (-90 +10 μm). According to the size distributions and manufacturing process, the plasma-sprayed YSZ particles were fully molten, resulting in dense coatings with good contact between the splats; the DSZ and, especially, the YbSZ particles were partially molten. In general, the surface residual stresses were slightly compressive before thermal cycling. The YSZ and DSZ coatings were insensitive to aging (600 h in air at room temperature), as shown by the surface stress evolution, which was not the case for YbSZ coatings. Six hundred furnace thermal cycles from 1100 °C to room temperature indicated excellent behavior of YSZ and DSZ coatings, with almost no variation of sur-face residual stresses, compared to a high dispersion for YbSZ coatings with the development of macrocracks parallel and perpendicular to the substrate within the coating.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  10. Thermal Insulation and Thermal Shock Behavior of Conventional and Nanostructured Plasma-Sprayed TBCs

    NASA Astrophysics Data System (ADS)

    Tamaddon Masoule, S.; Valefi, Z.; Ehsani, N.; Qazi Lavasani, H.

    2016-12-01

    This study investigated the thermal insulation and thermal shock resistance behavior of nanostructured versus conventional yttria-stabilized zirconia (YSZ) thermal barrier coatings. To evaluate their coating performance in service conditions, samples were furnace sintered at 1150 °C for 100 h in ambient atmosphere. The results show that the nanostructured coatings exhibited better heat transfer resistance and thermal shock resistance compared with the conventional coating. In addition, the larger size of the initial agglomerates in the nanostructured coatings increased the percentage area of nanozones and decreased the heat transfer resistance. The thermal insulation behavior of the conventional coating was improved after heat treatment because of horizontal cracking. Disappearance of cracks, bridging between grains, and their growth by connecting with each other were observed in the conventional coating. However, in the nanostructured coatings, the nanoareas and their related properties disappeared. Microstructural and phase investigations were carried out by optical microscopy, field-emission scanning electron microscopy (FE-SEM), and x-ray diffraction (XRD) analysis. The thermal behavior was investigated by thermal insulation capability testing.

  11. Oxidation and Hot Corrosion Behavior of Plasma-Sprayed MCrAlY-Cr2O3 Coatings

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    The oxidation and hot corrosion behavior of two atmospheric plasma-sprayed NiCoCrAlY-Cr2O3 and CoNiCrAlY-Cr2O3 coatings, which are primarily designed for wear applications at high temperature, were investigated in this study. The two coatings were exposed to air and molten salt (75%Na2SO4-25%NaCl) environment at 800 °C under cyclic conditions. Oxidation and hot corrosion kinetic curves were obtained by thermogravimetric technique. X-ray diffraction analysis and scanning electron microscopy with energy-dispersive x-ray spectrometry were employed to characterize the coatings' microstructure, surface oxides, and composition. The results showed that both coatings provided the necessary oxidation resistance with oxidation rates of about 1.03 × 10-2 and 1.36 × 10-2 mg/cm2 h, respectively. The excellent oxidation behavior of these two coatings is attributed to formation of protective (Ni,Co)Cr2O4 spinel on the surface, while as-deposited Cr2O3 in the coatings also acted as a barrier to diffusion of oxidative and corrosive substances. The greater presence of Co in the CoNiCrAlY-Cr2O3 coating restrained internal diffusion of sulfur and slowed down the coating's degradation. Thus, the CoNiCrAlY-Cr2O3 coating was found to be more protective than the NiCoCrAlY-Cr2O3 coating under hot corrosion condition.

  12. Hot Corrosion Behavior of Cold-Sprayed Ni-50Cr Coating in an Incinerator Environment at 900 °C

    NASA Astrophysics Data System (ADS)

    Singh, Harminder; Sidhu, T. S.; Kalsi, S. B. S.; Karthikeyan, J.

    2015-02-01

    In the present study, 50%Ni-50%Cr coating was developed on Superni 75 superalloy by a novel and facile cold-spray coating deposition technique. Dense, adhered, and oxide-free cold-sprayed coating was obtained in this study. This coating effectively provided corrosion protection to the substrate in real service incinerator conditions at 900 °C. The corrosion rate of the coated alloy was 0.47 mm/year, compared with 1.04 mm/year for bare alloy. This study indicates that the cold-spray process is an effective alternative for depositing high-temperature corrosion-resistant coatings.

  13. Effect of Coating Process Condition on High-Temperature Oxidation and Mechanical Failure Behavior for Plasma Sprayed Thermal Barrier Coating Systems

    NASA Astrophysics Data System (ADS)

    Takahashi, Satoru; Yoshiba, Masayuki; Harada, Yoshio

    In order to clarify the thermal and/or mechanical failure behavior of the plasma sprayed thermal barrier coating (TBC) system in connection with their coating characteristics depending on the coating process condition, two kinds of the failure analytical tests were conducted for TBC systems processed under different conditions. One was the high-temperature oxidation test, which was conducted at 1100°C under both the isothermal and thermal cycle conditions. The other was the in-situ observation of mechanical failure behavior, which was conducted under the static loadings at ambient temperature; as the most fundamental aspect, by means of an optical microscopy. It was found that the thermal and mechanical failure behavior of TBC system depends strongly on the top-coat (TC)/bond-coat (BC) interfacial condition, the reheat-treatment (RHT) after spraying and so on. For the TBC system with vacuum plasma sprayed (VPS) BC as well as for that with atmospheric plasma sprayed (APS) BC, in particular, the RHT at an appropriate temperature in Ar atmosphere was found to be effective for improving the oxidation property. For the TBC system with APS-BC, however, it was impossible to prevent the crack growth into the BC interior under the tensile loading in spite of conducting the RHT, since the microdefects such as oxides within the APS-BC tend to provide an easy crack propagation path. Furthermore, it was clarified that the smoothening process on the BC surface is able to prevent perfectly the occurrence of the wart-like oxide during oxidation, but at the same time increases also the risk of the TC spalling under the mechanical loading.

  14. High Temperature Damping Behavior of Plasma-Sprayed Thermal Barrier and Protective Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.; Duffy, Kirsten P.; Ghosn, Louis J.

    2010-01-01

    A high temperature damping test apparatus has been developed using a high heat flux CO 2 laser rig in conjunction with a TIRA S540 25 kHz Shaker and Polytec OFV 5000 Vibrometer system. The test rig has been successfully used to determine the damping performance of metallic and ceramic protective coating systems at high temperature for turbine engine applications. The initial work has been primarily focused on the microstructure and processing effects on the coating temperature-dependence damping behavior. Advanced ceramic coatings, including multicomponent tetragonal and cubic phase thermal barrier coatings, along with composite bond coats, have also been investigated. The coating high temperature damping mechanisms will also be discussed.

  15. The Wear Behavior of HVOF Sprayed Near-Nanostructured WC-17%Ni(80/20)Cr Coatings in Dry and Slurry Wear Conditions

    NASA Astrophysics Data System (ADS)

    Ben Mahmud, Tarek A.; Atieh, Anas M.; Khan, Tahir I.

    2017-07-01

    The ability to deposit nanostructured feedstock by using high-velocity oxygen-fuel (HVOF) spray offers potential improvements in coating hardness, wear resistance and toughness for applications in the oil sands industry. In this study, the wear behavior of a near-nanostructured coating was compared under dry and slurry abrasive wear test using an uncoated AISI-1018 low-carbon steel substrate as a reference. The coating microstructures were analyzed in the as-sprayed, dry and slurry test conditions using scanning electron microscopy, x-ray diffraction and microhardness measurements. Wear behavior of the steel and coating surfaces were assessed using a pin-on-plate wear test under various loads. The results showed that a coating could be successfully deposited using the HVOF spraying technique and with retention of the near-nanosized WC dispersion within the coating structure. The wear rate under dry test conditions was greater for the steel and coating compared to tests performed under slurry conditions. Examination of the wear tracks revealed that the wear mechanism was different for the two test conditions. Wear in the dry test condition resulted from 2-body abrasion, while 3-body abrasion dominated wear in slurry conditions. The latter showed lower wear rates due to a lubricating effect of the oil.

  16. A Study on Cavitation Erosion and Corrosion Behavior of Al-, Zn-, Cu-, and Fe-Based Coatings Prepared by Arc Spraying

    NASA Astrophysics Data System (ADS)

    Kim, Jin-Hong; Lee, Myeong-Hoon

    2010-12-01

    Investigation to find a suitable coating material for a rudder application has been carried out in this study. Ten different coatings were prepared by arc spraying with Al-, Zn-, Cu-, and Fe-based wire feedstock. Both the cavitation erosion and marine corrosion behavior of the arc-sprayed coatings were evaluated, and compared with the conventional anti-corrosion paint. In terms of marine corrosion resistance, aluminum coating was the best among the tested coating systems while stainless steel coating showed the highest resistance against cavitation erosion. In addition, the effects of both the Si composition in Al-based coatings and the Ni composition in Cu- and Fe- based coatings were discussed in this study.

  17. The macroscopic pancake bounce

    NASA Astrophysics Data System (ADS)

    Andersen Bro, Jonas; Sternberg Brogaard Jensen, Kasper; Nygaard Larsen, Alex; Yeomans, Julia M.; Hecksher, Tina

    2017-01-01

    We demonstrate that the so-called pancake bounce of millimetric water droplets on surfaces patterned with hydrophobic posts (Liu et al 2014 Nat. Phys. 10 515) can be reproduced on larger scales. In our experiment, a bed of nails plays the role of the structured surface and a water balloon models the water droplet. The macroscopic version largely reproduces the features of the microscopic experiment, including the Weber number dependence and the reduced contact time for pancake bouncing. The scalability of the experiment confirms the mechanisms of pancake bouncing, and allows us to measure the force exerted on the surface during the bounce. The experiment is simple and inexpensive and is an example where front-line research is accessible to student projects.

  18. Entanglement in macroscopic systems

    NASA Astrophysics Data System (ADS)

    Sperling, J.; Walmsley, I. A.

    2017-06-01

    We present a theoretical study of entanglement in ensembles consisting of an arbitrary number of particles. Multipartite entanglement criteria in terms of observables are formulated for a fixed number of particles as well as for systems with a fluctuating particle number. To access the quality of the verified entanglement, the operational measure of the entanglement visibility is introduced. As an example, we perform an analytical characterization of quantum systems composed of interacting harmonic oscillators and witness the entanglement via energy measurements. Our analysis shows that the detectable entanglement decays for macroscopic particle numbers without the need for decoherence processes and for all considered coupling regimes. We further study thermal states of the given correlated system together with the temperature dependence of entanglement.

  19. Nuclear physics: Macroscopic aspects

    SciTech Connect

    Swiatecki, W.J.

    1993-12-01

    A systematic macroscopic, leptodermous approach to nuclear statics and dynamics is described, based formally on the assumptions {h_bar} {yields} 0 and b/R << 1, where b is the surface diffuseness and R the nuclear radius. The resulting static model of shell-corrected nuclear binding energies and deformabilities is accurate to better than 1 part in a thousand and yields a firm determination of the principal properties of the nuclear fluid. As regards dynamics, the above approach suggests that nuclear shape evolutions will often be dominated by dissipation, but quantitative comparisons with experimental data are more difficult than in the case of statics. In its simplest liquid drop version the model exhibits interesting formal connections to the classic astronomical problem of rotating gravitating masses.

  20. Nonlocal correlations in a macroscopic measurement scenario

    NASA Astrophysics Data System (ADS)

    Kunkri, Samir; Banik, Manik; Ghosh, Sibasish

    2017-02-01

    Nonlocality is one of the main characteristic features of quantum systems involving more than one spatially separated subsystem. It is manifested theoretically as well as experimentally through violation of some local realistic inequality. On the other hand, classical behavior of all physical phenomena in the macroscopic limit gives a general intuition that any physical theory for describing microscopic phenomena should resemble classical physics in the macroscopic regime, the so-called macrorealism. In the 2-2-2 scenario (two parties, with each performing two measurements and each measurement having two outcomes), contemplating all the no-signaling correlations, we characterize which of them would exhibit classical (local realistic) behavior in the macroscopic limit. Interestingly, we find correlations which at the single-copy level violate the Bell-Clauser-Horne-Shimony-Holt inequality by an amount less than the optimal quantum violation (i.e., Cirel'son bound 2 √{2 } ), but in the macroscopic limit gives rise to a value which is higher than 2 √{2 } . Such correlations are therefore not considered physical. Our study thus provides a sufficient criterion to identify some of unphysical correlations.

  1. The Dry Sliding Wear Behavior of HVOF-Sprayed WC: Metal Composite Coatings

    NASA Astrophysics Data System (ADS)

    Ward, Liam P.; Pilkington, Antony

    2014-09-01

    WC-based cermet coatings containing various metallic binders such as Ni, Co, and Cr are known for their superior tribological properties, particularly abrasion resistance and enhanced surface hardness. Consequently, these systems are considered as replacements for traditional hard chrome coatings in critical aircraft components such as landing gear. The purpose of this investigation was to conduct a comparative study on the dry sliding wear behavior of three WC-based cermet coatings (WC-12Ni, WC-20Cr2C3-7Ni, and WC-10Co-4Cr), when deposited on carbon steel substrates. Ball on disk wear tests were performed on the coatings using a CSEM Tribometer (pin-on-disk) with a 6-mm ruby ball at 20 N applied load, 0.2 m/s sliding velocity, and sliding distances up to 2000 m. Analysis of both the coating wear track and worn ruby ball was performed using optical microscopy and an Alphastep-250 profilometer. The results of the study revealed both wear of the ruby ball and coated disks allowed for a comparison of both the ball wear and coating wear for the systems considered. Generally, the use of Co and Cr as a binder significantly improved the sliding wear resistance of the coating compared to Ni and/or Cr2C3.

  2. Low-temperature magnetic behavior of nanostructured ferrite compositions prepared by plasma spraying

    NASA Astrophysics Data System (ADS)

    Lepeshev, A. A.; Ushakov, A. V.; Karpov, I. V.

    2017-09-01

    Peculiarities of low-temperature behavior of the magnetic properties of disordered spinel ferrites, prepared by means of dilution with the P2O5 amorphizing agent and by rapid quenching, were investigated. A sharp increase in the saturation magnetization σS, of ferrite compositions (1-x)MeFe2O4.xP2O5 (where Me is Ni, Fe, Mn, etc.), was observed at temperatures T < 80 K. It was established that the temperature dependences of σS and χ-1 (where χ is the magnetic susceptibility) of the nickel ferrite composition (x = 0.6) have an extremum at T = 11 K. In this case, the effect of "memory" is observed for σS(T), which represents the dependence of σS (T = 4.2 K) on the magnitude of the magnetic field in which cooling was carried out. The asymptotic Curie temperature was determined by extrapolation of the linear part of the χ-1(T) dependence and found to be equal to -150 K. We present an analysis of the observed dependences from the viewpoint of a complex magnetic state, combining the features of the near antiferromagnetic and ferrimagnetic boundary-surface spin ordering.

  3. Microstructure Effect of Intermediate Coat Layer on Corrosion Behavior of HVAF-Sprayed Bi-Layer Coatings

    NASA Astrophysics Data System (ADS)

    Sadeghimeresht, Esmaeil; Markocsan, Nicolaie; Nylén, Per

    2017-01-01

    The inherent pores and carbides of Cr3C2-NiCr coatings significantly reduce the corrosion resistance, the former by providing preferential paths for ion diffusion and the latter by forming cathodic sites in galvanic couples (between NiCr and Cr3C2). Adding a dense intermediate layer (intermediate coat layer) between the Cr3C2-NiCr coating (top coat) and substrate increases the corrosion protection of the coating if the layer acts as cathode in connection to the top coat. In the present work, NiCr, NiAl, and NiCoCrAlY layers were deposited by high-velocity air-fuel process as intermediate coat layers for the Cr3C2-NiCr top coat. Effects of coating microstructure on corrosion behavior of single- and bi-layer coatings were studied by open-circuit potential and polarization tests in 3.5 wt.% NaCl at room temperature. A zero resistance ammeter technique was used to study the galvanic corrosion of the coupled top and intermediate coat layers. Methods such as SEM and XRD were employed to characterize the as-sprayed and corroded coatings and to investigate the corrosion mechanisms. The results showed that the NiCoCrAlY coating not only presented a more positive corrosion potential ( Ecorr) than the Cr3C2-NiCr coating, but also provided a better passive layer than the single-phase NiCr and NiAl coatings.

  4. Effects of Fungicide and Adjuvant Sprays on Nesting Behavior in Two Managed Solitary Bees, Osmia lignaria and Megachile rotundata

    PubMed Central

    2015-01-01

    There is a growing body of empirical evidence showing that wild and managed bees are negatively impacted by various pesticides that are applied in agroecosystems around the world. The lethal and sublethal effects of two widely used fungicides and one adjuvant were assessed in cage studies in California on blue orchard bees, Osmia lignaria, and in cage studies in Utah on alfalfa leafcutting bees, Megachile rotundata. The fungicides tested were Rovral 4F (iprodione) and Pristine (mixture of pyraclostrobin + boscalid), and the adjuvant tested was N-90, a non-ionic wetting agent (90% polyethoxylated nonylphenol) added to certain tank mixtures of fungicides to improve the distribution and contact of sprays to plants. In separate trials, we erected screened cages and released 20 paint-marked females plus 30–50 males per cage to document the behavior of nesting bees under treated and control conditions. For all females in each cage, we recorded pollen-collecting trip times, nest substrate-collecting trip times (i.e., mud for O. lignaria and cut leaf pieces for M. rotundata), cell production rate, and the number of attempts each female made to enter her own or to enter other nest entrances upon returning from a foraging trip. No lethal effects of treatments were observed on adults, nor were there effects on time spent foraging for pollen and nest substrates and on cell production rate. However, Rovral 4F, Pristine, and N-90 disrupted the nest recognition abilities of O. lignaria females. Pristine, N-90, and Pristine + N-90 disrupted nest recognition ability of M. rotundata females. Electroantennogram responses of antennae of O. lignaria females maintained in the laboratory did not differ significantly between the fungicide-exposed and control bees. Our results provide the first empirical evidence that two commonly used fungicides and a non-ionic adjuvant can disrupt nest recognition in two managed solitary bee species. PMID:26274401

  5. Effects of Fungicide and Adjuvant Sprays on Nesting Behavior in Two Managed Solitary Bees, Osmia lignaria and Megachile rotundata.

    PubMed

    Artz, Derek R; Pitts-Singer, Theresa L

    2015-01-01

    There is a growing body of empirical evidence showing that wild and managed bees are negatively impacted by various pesticides that are applied in agroecosystems around the world. The lethal and sublethal effects of two widely used fungicides and one adjuvant were assessed in cage studies in California on blue orchard bees, Osmia lignaria, and in cage studies in Utah on alfalfa leafcutting bees, Megachile rotundata. The fungicides tested were Rovral 4F (iprodione) and Pristine (mixture of pyraclostrobin + boscalid), and the adjuvant tested was N-90, a non-ionic wetting agent (90% polyethoxylated nonylphenol) added to certain tank mixtures of fungicides to improve the distribution and contact of sprays to plants. In separate trials, we erected screened cages and released 20 paint-marked females plus 30-50 males per cage to document the behavior of nesting bees under treated and control conditions. For all females in each cage, we recorded pollen-collecting trip times, nest substrate-collecting trip times (i.e., mud for O. lignaria and cut leaf pieces for M. rotundata), cell production rate, and the number of attempts each female made to enter her own or to enter other nest entrances upon returning from a foraging trip. No lethal effects of treatments were observed on adults, nor were there effects on time spent foraging for pollen and nest substrates and on cell production rate. However, Rovral 4F, Pristine, and N-90 disrupted the nest recognition abilities of O. lignaria females. Pristine, N-90, and Pristine + N-90 disrupted nest recognition ability of M. rotundata females. Electroantennogram responses of antennae of O. lignaria females maintained in the laboratory did not differ significantly between the fungicide-exposed and control bees. Our results provide the first empirical evidence that two commonly used fungicides and a non-ionic adjuvant can disrupt nest recognition in two managed solitary bee species.

  6. Local realism of macroscopic correlations.

    PubMed

    Ramanathan, R; Paterek, T; Kay, A; Kurzyński, P; Kaszlikowski, D

    2011-08-05

    We identify conditions under which correlations resulting from quantum measurements performed on macroscopic systems (systems composed of a number of particles of the order of the Avogadro number) can be described by local realism. We argue that the emergence of local realism at the macroscopic level is caused by an interplay between the monogamous nature of quantum correlations and the fact that macroscopic measurements do not reveal properties of individual particles.

  7. Local Realism of Macroscopic Correlations

    NASA Astrophysics Data System (ADS)

    Ramanathan, R.; Paterek, T.; Kay, A.; Kurzyński, P.; Kaszlikowski, D.

    2011-08-01

    We identify conditions under which correlations resulting from quantum measurements performed on macroscopic systems (systems composed of a number of particles of the order of the Avogadro number) can be described by local realism. We argue that the emergence of local realism at the macroscopic level is caused by an interplay between the monogamous nature of quantum correlations and the fact that macroscopic measurements do not reveal properties of individual particles.

  8. Effect of spark plasma sintering on the microstructure and in vitro behavior of plasma sprayed HA coatings.

    PubMed

    Yu, L-G; Khor, K A; Li, H; Cheang, P

    2003-07-01

    The crystalline phases and degree of crystallinity in plasma sprayed calcium phosphate coatings on Ti substrates are crucial factors that influence the biological interactions of the materials in vivo. In this study, plasma sprayed hydroxyapatite (HA) coatings underwent post-spray treatment by the spark plasma sintering (SPS) technique at 500 degrees C, 600 degrees C, and 700 degrees C for duration of 5 and 30 min. The activity of the HA coatings before and after SPS are evaluated in vitro in a simulated body fluid. The surface microstructure, crystallinity, and phase composition of each coating is characterized by scanning electron microscopy and X-ray diffractometry before, and after in vitro incubation. Results show that the plasma sprayed coatings treated for 5 min in SPS demonstrated increased proportion of beta-TCP phase with a preferred-orientation in the (214) plane, and the content of beta-TCP phase corresponded to SPS temperature, up to 700 degrees C. SPS treatment at 700 degrees C for 30 min enhanced the HA content in the plasma spray coating as well. The HA coatings treated in SPS for 5 min revealed rapid surface morphological changes during in vitro incubation (up to 12 days), indicating that the surface activity is enhanced by the SPS treatment. The thickest apatite layer was found in the coating treated by SPS at 700 degrees C for 5 min.

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  10. Acoustic effects of sprays

    NASA Technical Reports Server (NTRS)

    Pindera, Maciej Z.; Przekwas, Andrzej J.

    1994-01-01

    Since the early 1960's, it has been known that realistic combustion models for liquid fuel rocket engines should contain at least a rudimentary treatment of atomization and spray physics. This is of particular importance in transient operations. It has long been recognized that spray characteristics and droplet vaporization physics play a fundamental role in determining the stability behavior of liquid fuel rocket motors. This paper gives an overview of work in progress on design of a numerical algorithm for practical studies of combustion instabilities in liquid rocket motors. For flexibility, the algorithm is composed of semi-independent solution modules, accounting for different physical processes. Current findings are report and future work is indicated. The main emphasis of this research is the development of an efficient treatment to interactions between acoustic fields and liquid fuel/oxidizer sprays.

  11. Comparative characteristic and erosion behavior of NiCr coatings deposited by various high-velocity oxyfuel spray processes

    NASA Astrophysics Data System (ADS)

    Sidhu, Hazoor Singh; Sidhu, Buta Singh; Prakash, S.

    2006-12-01

    The purpose of this study is to analyze and compare the mechanical properties and microstructure details at the interface of high-velocity oxyfuel (HVOF)-sprayed NiCr-coated boiler tube steels, namely ASTM-SA-210 grade A1, ASTM-SA213-T-11, and ASTM-SA213-T-22. Coatings were developed by two different techniques, and in these techniques liquefied petroleum gas was used as the fuel gas. First, the coatings were characterized by metallographic, scanning electron microscopy/energy-dispersive x-ray analysis, x-ray diffraction, surface roughness, and microhardness, and then were subjected to erosion testing. An attempt has been made to describe the transformations taking place during thermal spraying. It is concluded that the HVOF wire spraying process offers a technically viable and cost-effective alternative to HVOF powder spraying process for applications in an energy generation power plant with a point view of life enhancement and to minimize the tube failures because it gives a coating having better resistance to erosion.

  12. Wind tunnel and field evaluation of drift from aerial spray applications with multiple spray formulations

    USDA-ARS?s Scientific Manuscript database

    The impact of different spray tank modifiers into an active ingredient spray mixture on spray atomization and in-field behavior under aerial application conditions were examined. Wind tunnel tests demonstrated that active ingredient solutions potentially results in significantly different atomizati...

  13. Compressional behavior of a mixture of granules containing high load of Phyllanthus niruri spray-dried extract and granules of adjuvants: comparison between eccentric and rotary tablet machines.

    PubMed

    Spaniol, Bárbara; Bica, Vinicius Claudino; Ruppenthal, Lisias Rafael; Volpato, Maria Ramos; Petrovick, Pedro Ros

    2009-01-01

    The purpose of this paper was to evaluate the compressional behavior of granules containing high load of a Phyllanthus niruri spray-dried extract in eccentric (ETM) and rotary (RTM) tablet presses. Tablets were constituted by spray-dried extract granules (SDEG, 92%), excipient granules (EXCG, 7.92%), and magnesium stearate (0.08%). SDEG was obtained by dry granulation and EXCG, composed of microcrystalline cellulose (62.9%) and sodium starch glycolate (37.1%), by wet granulation. Particle size distribution was fixed between 0.250 and 0.850 mm. Tablets did not evidence any mechanical failures, such as lamination or capping, or anomalous weight variation in either tablet machine types. Upper and lower tablet surface photomicrographs from ETM and RTM tablets showed differences in porosity and texture. Different RTM speeds suggested the visco-plastic behavior of the formulation, since, by slowing down rotation speeds, the tensile strength of the tablets increased significantly, but the porosity and disintegration time were not affected. Tablets produced in RTM showed lower friability and porosity than ETM tablets, which did not reflect on higher tensile strength. The EXCG distribution at upper and lower surfaces from ETM and RTM tablets was quantified by image analysis and evaluated through statistical methods. Spray-dried extract release was not influenced by the type of equipment or operational conditions to which the compacts were submitted. Construction and operation differences between both tablet presses influenced the final product, since tablets with similar tensile strength, made by distinct tablet machines, exhibited different quality parameters.

  14. A Study on the Cyclic Oxidation Behavior of Detonation-Gun-Sprayed Ni-5Al Coatings on Inconel-718 at 900 °C

    NASA Astrophysics Data System (ADS)

    Saladi, Sekar; Menghani, Jyoti; Prakash, Satya

    2014-12-01

    Cyclic oxidation behavior of detonation-gun-sprayed Ni-5Al coating on Inconel-718 is discussed in the present study. Oxidation studies were carried out on both bare and coated superalloy substrates in air at 900 °C for 100 cycles. The thermogravimetric technique was used to establish kinetics of oxidation. X-ray diffraction, FESEM/EDAX, and x-ray mapping techniques were used to analyze the oxidation products of bare and coated samples. The weight gain of bare superalloy was higher than the Ni-5Al-coated superalloy. Both bare and Ni-5Al-coated superalloys followed nearly parabolic oxidation behavior. The Ni-5Al coating was able to reduce the overall weight gain by 26.2% in comparison with bare superalloy in the given environment. The better oxidation resistance of Ni-5Al coating may be due the formation of protective oxides phases such as NiO, Al2O3, and NiAl2O4 on the oxidized coating and Cr2O3 at the coating-substrate interface. The Ni-5Al coatings obtained from detonation-gun-spraying process showed very little porosity and low surface roughness values.

  15. Investigation on the Clogging Behavior and Additional Wall Cooling for the Axial-Injection Cold Spray Nozzle

    NASA Astrophysics Data System (ADS)

    Wang, Xudong; Zhang, Bo; Lv, Jinsheng; Yin, Shuo

    2015-04-01

    During the cold spray process, nozzle clogging always happens when spraying low-melting point materials, e.g., aluminum, significantly decreasing the working efficiency. In this paper, a comprehensive investigation was carried out to clarify the reason for inducing nozzle clogging and then to evaluate a home-made nozzle cooling device for preventing nozzle clogging. Computational fluid dynamics technique was employed as the main method with some necessary experiment validation. It is found that the particle dispersion and the high-temperature nozzle wall at the near-throat region are two dominant factors that cause nozzle clogging. The numerical results also reveal that the home-made cooling device can significantly reduce the nozzle wall temperature, which was validated by the experimental measurement. Besides, the aluminum coating build-up experiment further indicates that the additional cooling device can truly prevent the nozzle clogging.

  16. High-temperature thermo-mechanical behavior of functionally graded materials produced by plasma sprayed coating: Experimental and modeling results

    NASA Astrophysics Data System (ADS)

    Choi, Kang Hyun; Kim, Hyun-Su; Park, Chang Hyun; Kim, Gon-Ho; Baik, Kyoung Ho; Lee, Sung Ho; Kim, Taehyung; Kim, Hyoung Seop

    2016-09-01

    Thermal barrier coatings are widely used in aerospace industries to protect exterior surfaces from harsh environments. In this study, functionally graded materials (FGMs) were investigated with the aim to optimize their high temperature resistance and strength characteristics. NiCrAlY bond coats were deposited on Inconel-617 superalloy substrate specimens by the low vacuum plasma spraying technique. Functionally graded Ni-yttria-stabilized zirconia (YSZ) coatings with gradually varying amounts of YSZ (20%-100%) were fabricated from composite powders by vacuum plasma spraying. Heat shield performance tests were conducted using a high- temperature plasma torch. The temperature distributions were measured using thermocouples at the interfaces of the FGM layers during the tests. A model for predicting the temperature at the bond coating-substrate interface was established. The temperature distributions simulated using the finite element method agreed well with the experimental results.

  17. Continuous Feedback and Macroscopic Coherence

    NASA Technical Reports Server (NTRS)

    Tombesi, Paolo; Vitali, David

    1996-01-01

    We show that a model, recently introduced for quantum nondemolition measurements of a quantum observable, can be adapted to obtain a measurement scheme which is able to slow down the destruction of macroscopic coherence due to the measurement apparatus.

  18. Oxidation Behavior of In-Flight Molten Aluminum Droplets in the Twin-Wire Electric Arc Thermal Spray Process

    SciTech Connect

    Donna Post Guillen; Brian G. Williams

    2005-05-01

    This paper examines the in-flight oxidation of molten aluminum sprayed in air using the twin-wire electric arc (TWEA) thermal spray process. The oxidation reaction of aluminum in air is highly exothermic and is represented by a heat generation term in the energy balance. Aerodynamic shear at the droplet surface enhances the amount of in-flight oxidation by: (1) promoting entrainment and mixing of the surface oxides within the droplet, and (2) causing a continuous heat generation effect that increases droplet temperature over that of a droplet without internal circulation. This continual source of heat input keeps the droplets in a liquid state during flight. A linear rate law based on the Mott-Cabrera theory was used to estimate the growth of the surface oxide layer formed during droplet flight. The calculated oxide volume fraction of an average droplet at impact agrees well with the experimentally determined oxide content for a typical TWEA-sprayed aluminum coating, which ranges from 3.3 to 12.7%. An explanation is provided for the elevated, nearly constant surface temperature (~ 2000 oC) of the droplets during flight to the substrate and shows that the majority of oxide content in the coating is produced during flight, rather than after deposition.

  19. Macroscopic constraints on string unification

    SciTech Connect

    Taylor, T.R.

    1989-03-01

    The comparison of sting theory with experiment requires a huge extrapolation from the microscopic distances, of order of the Planck length, up to the macroscopic laboratory distances. The quantum effects give rise to large corrections to the macroscopic predictions of sting unification. I discus the model-independent constraints on the gravitational sector of string theory due to the inevitable existence of universal Fradkin-Tseytlin dilatons. 9 refs.

  20. Corrosion behaviors and effects of corrosion products of plasma electrolytic oxidation coated AZ31 magnesium alloy under the salt spray corrosion test

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Huang, Zhiquan; Yan, Qin; Liu, Chen; Liu, Peng; Zhang, Yi; Guo, Changhong; Jiang, Guirong; Shen, Dejiu

    2016-08-01

    The effects of corrosion products on corrosion behaviors of AZ31 magnesium alloy with a plasma electrolytic oxidation (PEO) coating were investigated under the salt spray corrosion test (SSCT). The surface morphology, cross-sectional microstructure, chemical and phase compositions of the PEO coating were determined using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction analysis (XRD), respectively. Further, the corrosion process of the samples under the SSCT was examined in a non-aqueous electrolyte (methanol) using electrochemical impedance spectroscopy (EIS) coupled with equivalent circuit. The results show that the inner layer of the coating was destroyed firstly and the corrosion products have significant effects on the corrosion behaviors of the coating. The results above are discussed and an electrochemical corrosion model is proposed in the paper.

  1. Effect of ultrasonic cavitation erosion on corrosion behavior of high-velocity oxygen-fuel (HVOF) sprayed near-nanostructured WC-10Co-4Cr coating.

    PubMed

    Hong, Sheng; Wu, Yuping; Zhang, Jianfeng; Zheng, Yugui; Qin, Yujiao; Lin, Jinran

    2015-11-01

    The effect of ultrasonic cavitation erosion on electrochemical corrosion behavior of high-velocity oxygen-fuel (HVOF) sprayed near-nanostructured WC-10Co-4Cr coating in 3.5 wt.% NaCl solution, was investigated using free corrosion potential, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) in comparison with stainless steel 1Cr18Ni9Ti. The results showed that cavitation erosion strongly enhanced the cathodic current density, shifted the free corrosion potential in the anodic direction, and reduced the magnitude of impedance of the coating. The impedance of the coating decreased more slowly under cavitation conditions than that of the stainless steel 1Cr18Ni9Ti, suggesting that corrosion behavior of the coating was less affected by cavitation erosion than that of the stainless steel.

  2. Influence of Cold-Sprayed, Warm-Sprayed, and Plasma-Sprayed Layers Deposition on Fatigue Properties of Steel Specimens

    NASA Astrophysics Data System (ADS)

    Cizek, J.; Matejkova, M.; Dlouhy, I.; Siska, F.; Kay, C. M.; Karthikeyan, J.; Kuroda, S.; Kovarik, O.; Siegl, J.; Loke, K.; Khor, Khiam Aik

    2015-06-01

    Titanium powder was deposited onto steel specimens using four thermal spray technologies: plasma spray, low-pressure cold spray, portable cold spray, and warm spray. The specimens were then subjected to strain-controlled cyclic bending test in a dedicated in-house built device. The crack propagation was monitored by observing the changes in the resonance frequency of the samples. For each series, the number of cycles corresponding to a pre-defined specimen cross-section damage was used as a performance indicator. It was found that the grit-blasting procedure did not alter the fatigue properties of the steel specimens (1% increase as compared to as-received set), while the deposition of coatings via all four thermal spray technologies significantly increased the measured fatigue lives. The three high-velocity technologies led to an increase of relative lives to 234% (low-pressure cold spray), 210% (portable cold spray), and 355% (warm spray) and the deposition using plasma spray led to an increase of relative lives to 303%. The observed increase of high-velocity technologies (cold and warm spray) could be attributed to a combination of homogeneous fatigue-resistant coatings and induction of peening stresses into the substrates via the impingement of the high-kinetic energy particles. Given the intrinsic character of the plasma jet (low-velocity impact of semi/molten particles) and the mostly ceramic character of the coating (oxides, nitrides), a hypothesis based on non-linear coatings behavior is provided in the paper.

  3. Failure Behavior of Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier Coatings Under Three-Point Bending Test via Acoustic Emission Technique

    NASA Astrophysics Data System (ADS)

    Wang, L.; Ni, J. X.; Shao, F.; Yang, J. S.; Zhong, X. H.; Zhao, H. Y.; Liu, C. G.; Tao, S. Y.; Wang, Y.; Li, D. Y.

    2017-01-01

    In this paper, the failure behavior of plasma-sprayed yttria-stabilized zirconia thermal barrier coatings fabricated by atmospheric plasma spraying (APS-TBCs) under three-point bending (3PB) test has been characterized via acoustic emission (AE) technique. Linear positioning method has been adopted to monitor dynamic failure process of the APS-TBCs under 3PB test. The investigation results indicate that the variation of AE parameters (AE event counts, amplitudes and AE energy) corresponds well with the change of stress-strain curve of the loading processes. The failure mechanism was analyzed based on the characteristics of AE parameters. The distribution of frequency of crack propagation has been obtained. The AE signals came from two aspects: i.e., plastic deformation of substrates, initiation and propagation of the cracks in the coatings. The AE analysis combined with cross-sectional observation has indicated that many critical cracks initiate at the surface of the top-coat. And some main cracks tend to propagate toward the substrate/bond-coat interface. The actual failure mechanism of the APS-TBCs under 3PB test is attributed to the debonding of metallic coating from the substrates and the propagation of the horizontal crack along the substrate/bond-coat interface under the action of flexural moment.

  4. Study of mechanical properties and high temperature oxidation behavior of a novel cold-spray Ni-20Cr coating on boiler steels

    NASA Astrophysics Data System (ADS)

    Kaur, Narinder; Kumar, Manoj; Sharma, Sanjeev K.; Kim, Deuk Young; Kumar, S.; Chavan, N. M.; Joshi, S. V.; Singh, Narinder; Singh, Harpreet

    2015-02-01

    In the current investigation, high temperature oxidation behavior of a novel cold-spray Ni-20Cr nanostructured coating was studied. The nanocrystalline Ni-20Cr powder was synthesized by the investigators using ball milling, which was deposited on T22 and SA 516 steels by cold spraying. The crystallite size based upon Scherrer's formula for the developed coatings was found to be in nano-range for both the substrates. The accelerated oxidation testing was performed in a laboratory tube furnace at a temperature 900 °C under thermal cyclic conditions. Each cycle comprised heating for one hour at 900 °C followed by cooling for 20 min in ambient air. The kinetics of oxidation was established using weight change measurements for the bare and the coated steels. The oxidation products were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS) and X-ray mapping techniques. It was found from the results that the coating was successful in reducing the weight gain of SA213-T22 and SA 516-Grade 70 steel by 71% and 94%, respectively. This may be attributed to relatively denser structure, lower porosity and lower oxide content of the coating. Moreover, the developed nano-structured Ni-20Cr powder coating was found to perform better than its counterpart micron-sized Ni-20Cr powder coating, in terms of offering higher oxidation resistance and hardness.

  5. The influence of spray-drying parameters on phase behavior, drug distribution, and in vitro release of injectable microspheres for sustained release.

    PubMed

    Meeus, Joke; Lenaerts, Maité; Scurr, David J; Amssoms, Katie; Davies, Martyn C; Roberts, Clive J; Van Den Mooter, Guy

    2015-04-01

    For ternary solid dispersions, it is indispensable to characterize their structure, phase behavior, and the spatial distribution of the dispersed drug as this might influence the release profile and/or stability of these formulations. This study shows how formulation (feed concentration) and process (feed rate, inlet air temperature, and atomizing air pressure) parameters can influence the characteristics of ternary spray-dried solid dispersions. The microspheres considered here consist of a poly(lactic-co-glycolic acid) (PLGA) surface layer and an underlying polyvinylpyrrolidone (PVP) phase. A poorly soluble active pharmaceutical ingredient (API) was molecularly dispersed in this matrix. Differences were observed in component miscibility, phase heterogeneity, particle size, morphology, as well as API surface coverage for selected spray-drying parameters. Observed differences are likely because of changes in the droplet generation, evaporation, and thus particle formation processes. However, varying particle characteristics did not influence the drug release of the formulations studied, indicating the robustness of this approach to produce particles of consistent drug release characteristics. This is likely because of the fact that the release is dominated by diffusion from the PVP layer through pores in the PLGA surface layer and that observed differences in the latter have no influence on the release.

  6. Investigation into the diffusion and oxidation behavior of the interface between a plasma-sprayed anode and a porous steel support for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Zhang, Shan-Lin; Li, Cheng-Xin; Li, Chang-Jiu; Liu, Meilin; Yang, Guan-Jun

    2016-08-01

    Porous metal-supported solid oxide fuel cells (SOFCs) have attracted much attention because their potential to dramatically reduce the cost while enhancing the robustness and manufacturability. In particular, 430 ferritic steel (430L) is one of the popular choice for SOFC support because of its superior performance and low cost. In this study, we investigate the oxidation and diffusion behavior of the interface between a Ni-based anode and porous 430L support exposed to a humidified (3% H2O) hydrogen atmosphere at 700 °C. The Ni-GDC (Ce0.8Gd0.2O2-δ) cermet anodes are deposited on the porous 430L support by atmospheric plasma spraying (APS). The effect of exposure time on the microstructure and phase structure of the anode and the supports is studied and the element diffusion across the support/anode interface is characterized. Results indicate that the main oxidation product of the 430L support is Cr2O3, and that Cr and Fe will diffuse to the anode and the diffusion thickness increases with the exposure time. The diffusion thickness of Cr and Fe reach about 5 and 2 μm, respectively, after 1000 h exposure. However, the element diffusion and oxidation has little influence on the area-specific resistance, indicating that the porous 430L steel and plasma sprayed Ni-GDC anode are promising for durable SOFCs.

  7. Dry sliding wear behavior of ceramic-metal composite coatings prepared by plasma spraying of self-reacting powders

    NASA Astrophysics Data System (ADS)

    Dong, Yanchun; Yan, Dianran; He, Jining; Li, Xiangzhi; Zhang, Jianxin

    2006-09-01

    Ceramic-metal composite (CMC) coatings were deposited on the surface of Fe-0.14 0.22 wt.% C steel by plasma spraying of self-reacting Fe2O3-Al composite powders. The dry sliding friction and wear character of the CMC coatings are investigated in this paper. The wear resistance of the CMC coatings was significantly better than that of Al2O3 coatings under the same sliding wear conditions. The tough metal, which is dispersed in the ceramic matrix, obviously improved the toughness of the CMC coatings. Wear mechanisms of the CMC coatings were identified as a combination of abrasive and adhesive wear.

  8. Stereodynamics: From elementary processes to macroscopic chemical reactions

    SciTech Connect

    Kasai, Toshio; Che, Dock-Chil; Tsai, Po-Yu; Lin, King-Chuen; Palazzetti, Federico; Aquilanti, Vincenzo

    2015-12-31

    This paper aims at discussing new facets on stereodynamical behaviors in chemical reactions, i.e. the effects of molecular orientation and alignment on reactive processes. Further topics on macroscopic processes involving deviations from Arrhenius behavior in the temperature dependence of chemical reactions and chirality effects in collisions are also discussed.

  9. Processing and Composition Effects on the Fracture Behavior of Spray-Formed 7XXX Series Al Alloys

    NASA Astrophysics Data System (ADS)

    Sharma, M. M.; Ziemian, C. W.; Eden, T. J.

    2010-12-01

    The fracture properties of high-strength spray-formed Al alloys were investigated, with consideration of the effects of elemental additions such as zinc, manganese, and chromium and the influence of the addition of SiC particulate. Fracture resistance values between 13.6 and 25.6 MPa (m)1/2 were obtained for the monolithic alloys in the T6 and T7 conditions, respectively. The alloys with SiC particulate compared well and achieved fracture resistance values between 18.7 and 25.6 MPa (m)1/2. The spray-formed materials exhibited a loss in fracture resistance ( K I) compared to ingot metallurgy 7075 alloys but had an improved performance compared to high-solute powder metallurgy alloys of similar composition. Characterization of the fracture surfaces indicated a predominantly intergranular decohesion, possibly facilitated by the presence of incoherent particles at the grain boundary regions and by the large strength differential between the matrix and precipitate zone. It is believed that at the slip band-grain boundary intersection, particularly in the presence of large dispersoids and/or inclusions, microvoid nucleation would be significantly enhanced. Differences in fracture surfaces between the alloys in the T6 and T7 condition were observed and are attributed to inhomogeneous slip distribution, which results in strain localization at grain boundaries. The best overall combination of fracture resistance properties were obtained for alloys with minimum amounts of chromium and manganese additions.

  10. Degradation behavior of Ni{sub 3}Al plasma-sprayed boiler tube steels in an energy generation system

    SciTech Connect

    Sidhu, B.S.; Prakash, S.

    2005-06-01

    Boiler steels, namely, low-C steel, ASTM-SA210-Grade A1 (GrA1), 1Cr-0.5Mo steel, ASTM-SA213-T-11 (T11) and 2.25Cr-1Mo steel, ASTM-SA213-T-22 (T22) were plasma sprayed with Ni3Al. The alloy powder was prepared by mixing Ni and Al in the stoichiometric ratio of 3 to 1. The Ni-22Cr-10Al-1Y alloy powder was used as a bond coat, with a 150{mu} m thick layer sprayed onto the surface before applying the 200{mu}m coating of Ni{sub 3}Al. Exposure studies have been performed in the platen superheater zone of a coal-fired boiler at around 755{sup o}C for 10 cycles, each of 100 h duration. The protection to the base steel was minimal for the three steels. Scale spallation and the formation of a porous and nonadherent NiO scale were probably the main reasons for the lack of protection. In the case of T22-coated steel, cracks in the coatings have been observed after the first 100 h exposure cycle.

  11. Cyclic Oxidation Behavior of Cold Sprayed CuCrAl-Coated and Uncoated GRCop-84 Substrates for Space Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Raj, S. V.; Barrett, C.; Karthikeyan, J.; Garlick, R.

    2006-01-01

    A newly developed Cu-23 (wt %) Cr-5%Al (CuCrAl) alloy shown to resist hydridation and oxidation in an as-cast form is currently being considered as a protective coating for GRCop-84, which is an advanced copper alloy containing 8 (at.%) Cr and 4 (at.%) Nb. The coating was deposited on GRCop-84 substrates by the cold spray deposition technique. Cyclic oxidation tests conducted in air on both coated and uncoated substrates between 773 and 1073 K revealed that the coating remained intact and protected the substrate up to 1073 K. No significant weight loss of the coated specimens were observed at 773 and 873 K even after a cumulative cyclic time of 500 h. About a 10 percent weight loss observed at 973 and 1073 K was attributed to the excessive oxidation of the uncoated sides. In contrast, the uncoated substrate lost as much as 80 percent of its original weight under similar test conditions. It is concluded that the cold sprayed CuCrAl coating is suitable for protecting GRCop-84 substrates.

  12. Characterization and Wear Behavior of Heat-treated Ni3Al Coatings Deposited by Air Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Mehmood, K.; Rafiq, M. A.; Nusair Khan, A.; Ahmed, F.; Mudassar Rauf, M.

    2016-07-01

    Air plasma spraying was utilized to deposit Ni3Al coatings on AISI-321 steel substrate. The deposited coatings were isothermally heat-treated at various temperatures from 500 to 800 °C for 10, 30, 60, and 100 h. The x-ray diffraction analysis revealed NiO formation in Ni3Al at 500 °C after 100 h, and the percentage of NiO increased with increasing exposure time and temperature. The hardness of the coating increased with the formation of NiO. The DSC test showed the formation of minor phases, Al3Ni and Al3Ni2, within the coating along with the major phase Ni3Al. TGA revealed a slowing down of the oxidation rate upon surface oxide formation. The pin-on-disk wear test on the as-sprayed and heat-treated coatings showed that wear rate and coefficient of friction decreased with an increase in the NiO phase content.

  13. Are cloned quantum states macroscopic?

    PubMed

    Fröwis, F; Dür, W

    2012-10-26

    We study quantum states produced by optimal phase covariant quantum cloners. We argue that cloned quantum superpositions are not macroscopic superpositions in the spirit of Schrödinger's cat, despite their large particle number. This is indicated by calculating several measures for macroscopic superpositions from the literature, as well as by investigating the distinguishability of the two superposed cloned states. The latter rapidly diminishes when considering imperfect detectors or noisy states and does not increase with the system size. In contrast, we find that cloned quantum states themselves are macroscopic, in the sense of both proposed measures and their usefulness in quantum metrology with an optimal scaling in system size. We investigate the applicability of cloned states for parameter estimation in the presence of different kinds of noise.

  14. Macroscopic-microscopic mass models

    SciTech Connect

    Nix, J.R.; Moller, P.

    1995-07-01

    We discuss recent developments in macroscopic-microscopic mass models, including the 1992 finite-range droplet model, the 1992 extended- Thomas-Fermi Strutinsky-integral model, and the 1994 Thomas-Fermi model, with particular emphasis on how well they extrapolate to new regions of nuclei. We also address what recent developments in macroscopic-microscopic mass models are teaching us about such physically relevant issues as the nuclear curvature energy, a new congruence energy arising from a greater-than-average overlap of neutron and proton wave functions, the nuclear incompressibility coefficient, and the coulomb redistribution energy arising from a central density depression. We conclude with a brief discussion of the recently discovered rock of metastable superheavy nuclei near {sup 272}110 that had been correctly predicted by macroscopic-microscopic models, along with a possible new tack for reaching an island near {sup 290}110 beyond our present horizon.

  15. Agricultural Spraying

    NASA Technical Reports Server (NTRS)

    1986-01-01

    AGDISP, a computer code written for Langley by Continuum Dynamics, Inc., aids crop dusting airplanes in targeting pesticides. The code is commercially available and can be run on a personal computer by an inexperienced operator. Called SWA+H, it is used by the Forest Service, FAA, DuPont, etc. DuPont uses the code to "test" equipment on the computer using a laser system to measure particle characteristics of various spray compounds.

  16. Slurry Erosion Behavior of F6NM Stainless Steel and High-Velocity Oxygen Fuel-Sprayed WC-10Co-4Cr Coating

    NASA Astrophysics Data System (ADS)

    Cui, S. Y.; Miao, Q.; Liang, W. P.; Huang, B. Z.; Ding, Z.; Chen, B. W.

    2016-12-01

    WC-10Co-4Cr coating was applied to the surface of F6NM stainless steel by high-velocity oxygen-fuel spraying. The slurry erosion behavior of the matrix and coating was examined at different rotational speeds using a self-made machine. This experiment effectively simulates real slurry erosion in an environment with high silt load. At low velocity (<6 m/s), the main failure mechanism was cavitation. Small bubbles acted as an air cushion, obstructing direct contact between sand and the matrix surface. However, at velocity above 9 m/s, abrasive wear was the dominant failure mechanism. The results indicate that WC-10Co-4Cr coating significantly improved the slurry resistance at higher velocity, because it created a thin and dense WC coating on the surface.

  17. Peripheral olfactory deafferentation of the primary olfactory system in rats using ZnSO4 nasal spray with special reference to maternal behavior.

    PubMed

    Mayer, A D; Rosenblatt, J S

    1993-03-01

    A modified method of applying ZnSO4 to the olfactory mucosa is described. Treated rats experienced severe nasal congestion that cleared within 24 h; more persistent morbidity did not occur. Nonpregnant females observed with male intruders 24 h following ZnSO4 showed no alterations in behavior other than a reduction in anogenital sniffing, indicating that they were not hypoactive or irritable. In other experiments, lactating females were observed in a hole-board apparatus; 2 days posttreatment anosmia was confirmed in 80% of bilaterally ZnSO4-treated females by the absence of preference for pup odors. After bilateral but not unilateral ZnSO4 treatment, initially activity scores and nose pokes were equivalent in all groups, but later they both were lower than in controls, probably due to a more rapid habituation to the novel apparatus. We conclude that intranasal ZnSO4 by small-volume spray is a useful experimental tool.

  18. Slurry Erosion Behavior of F6NM Stainless Steel and High-Velocity Oxygen Fuel-Sprayed WC-10Co-4Cr Coating

    NASA Astrophysics Data System (ADS)

    Cui, S. Y.; Miao, Q.; Liang, W. P.; Huang, B. Z.; Ding, Z.; Chen, B. W.

    2017-02-01

    WC-10Co-4Cr coating was applied to the surface of F6NM stainless steel by high-velocity oxygen-fuel spraying. The slurry erosion behavior of the matrix and coating was examined at different rotational speeds using a self-made machine. This experiment effectively simulates real slurry erosion in an environment with high silt load. At low velocity (<6 m/s), the main failure mechanism was cavitation. Small bubbles acted as an air cushion, obstructing direct contact between sand and the matrix surface. However, at velocity above 9 m/s, abrasive wear was the dominant failure mechanism. The results indicate that WC-10Co-4Cr coating significantly improved the slurry resistance at higher velocity, because it created a thin and dense WC coating on the surface.

  19. Comparative High-Temperature Corrosion Behavior of Ni-20Cr Coatings on T22 Boiler Steel Produced by HVOF, D-Gun, and Cold Spraying

    NASA Astrophysics Data System (ADS)

    Kaushal, Gagandeep; Bala, Niraj; Kaur, Narinder; Singh, Harpreet; Prakash, Satya

    2014-01-01

    To protect materials from surface degradations such as wear, corrosion, and thermal flux, a wide variety of materials can be deposited on the materials by several spraying processes. This paper examines and compares the microstructure and high-temperature corrosion of Ni-20Cr coatings deposited on T22 boiler steel by high velocity oxy-fuel (HVOF), detonation gun spray, and cold spraying techniques. The coatings' microstructural features were characterized by means of XRD and FE-SEM/EDS analyses. Based upon the results of mass gain, XRD, and FE-SEM/EDS analyses it may be concluded that the Ni-20Cr coating sprayed by all the three techniques was effective in reducing the corrosion rate of the steel. Among the three coatings, D-gun spray coating proved to be better than HVOF-spray and cold-spray coatings.

  20. Hot Corrosion Behavior of Arc-Sprayed Highly Dense NiCr-Based Coatings in Chloride Salt Deposit

    NASA Astrophysics Data System (ADS)

    Qin, Enwei; Yin, Song; Ji, Hua; Huang, Qian; Liu, Zekun; Wu, Shuhui

    2017-03-01

    To make cities more environmentally friendly, combustible wastes tend to be incinerated in waste-to-energy power plant boilers. However, release of chlorine gas (Cl2) during incineration causes serious problems related to hot corrosion of boiler tubes and poses a safety threat for such plants. In this study, a pseudo-de Laval nozzle was employed in a twin-wire arc spray system to enhance the velocity of in-flight particles. Highly dense NiCr-based coatings were obtained using the modified nozzle gun. The coating morphology was characterized by optical microscopy and scanning electron microscopy, and hot corrosion testing was carried out in a synthetic molten chloride salt environment. Results showed that the dense NiCr-based coatings exhibited high resistance against corrosion by chlorine, which can be related to the typical splat lamellar microstructure and chemical composition as well as minor alloying elements such as Ti and Mo.

  1. Hot Corrosion Behavior of Arc-Sprayed Highly Dense NiCr-Based Coatings in Chloride Salt Deposit

    NASA Astrophysics Data System (ADS)

    Qin, Enwei; Yin, Song; Ji, Hua; Huang, Qian; Liu, Zekun; Wu, Shuhui

    2017-04-01

    To make cities more environmentally friendly, combustible wastes tend to be incinerated in waste-to-energy power plant boilers. However, release of chlorine gas (Cl2) during incineration causes serious problems related to hot corrosion of boiler tubes and poses a safety threat for such plants. In this study, a pseudo-de Laval nozzle was employed in a twin-wire arc spray system to enhance the velocity of in-flight particles. Highly dense NiCr-based coatings were obtained using the modified nozzle gun. The coating morphology was characterized by optical microscopy and scanning electron microscopy, and hot corrosion testing was carried out in a synthetic molten chloride salt environment. Results showed that the dense NiCr-based coatings exhibited high resistance against corrosion by chlorine, which can be related to the typical splat lamellar microstructure and chemical composition as well as minor alloying elements such as Ti and Mo.

  2. A Comparison of Mechanical and Tribological Behavior of Nanostructured and Conventional WC-12Co Detonation-Sprayed Coatings

    NASA Astrophysics Data System (ADS)

    Pitchuka, Suresh Babu; Basu, Bikramjit; Sundararajan, G.

    2013-04-01

    In the present study, WC-12Co coatings were deposited by detonation-spraying technique using conventional and nanostructured WC-12Co feedstock at four different oxy/fuel ratios (OF ratio). The coatings exhibited the presence of phases like W2C and W due to the decarburization of the WC phase, and the proportions of these phases were higher in the nano WC-12Co coatings compared with conventional WC-12Co coatings. Coating hardness and fracture toughness were measured. The tribological performance of coatings was examined under dry sand rubber wheel abrasion wear, and solid particle erosion wear conditions. The mechanical and wear properties of coatings were influenced by degree of decarburization and more so in the case of nanostructured WC-Co coatings. The results indicate that the extent of decarburization has a substantial influence on the elastic modulus of the coating which in turn is related to the extent of intersplat cracking of the coating.

  3. Oxidation behavior of HVOF-sprayed nanostructured and CeO2-modified WC-12Co coatings

    NASA Astrophysics Data System (ADS)

    Xi, Naiyuan; Hang, Zongqiu; Liu, Yan; Chen, Hui; Zhang, Mingyue; Gao, Wei

    2017-07-01

    Two types of WC-12Co coatings with different modifications were deposited on steel substrates using high velocity oxygen fuel (HVOF) spraying. The coated samples were oxidized at 550∘C and 650∘C in ambient atmosphere. Oxidation mass gain was measured by electronic balance. Phase composition and microstructure evolution of both coatings after oxidation were conducted by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Microhardness testing was performed before and after oxidation testing. The results showed that at 550∘C and 650∘C, the rare-earth modified WC-12Co coating has lower oxidation rates compared with the nanostructured WC-12Co coating. This might be due to the rare-earth modification coating reducing the porosity and oxygen diffusion in the coatings, therefore delaying the crack formation and propagation.

  4. Fatigue behavior of thermal sprayed WC-CoCr- steel systems: Role of process and deposition parameters

    DOE PAGES

    Vackel, Andrew; Sampath, Sanjay

    2017-02-27

    Thermal spray deposited WC-CoCr coatings are extensively used for surface protection of wear prone components in a variety of applications. Although the primary purpose of the coating is wear and corrosion protection, many of the coated components are structural systems (aero landing gear, hydraulic cylinders, drive shafts etc.) and as such experience cyclic loading during service and are potentially prone to fatigue failure. It is of interest to ensure that the coating and the application process does not deleteriously affect the fatigue strength of the parent structural metal. It has long been appreciated that the relative fatigue life of amore » thermal sprayed component can be affected by the residual stresses arising from coating deposition. The magnitude of these stresses can be managed by torch processing parameters and can also be influenced by deposition effects, particularly the deposition temperature. In this study, the effect of both torch operating parameters (particle states) and deposition conditions (notably substrate temperature) were investigated through rotating bending fatigue studies. The results indicate a strong influence of process parameters on relative fatigue life, including credit or debit to the substrate's fatigue life measured via rotating bend beam studies. Damage progression within the substrate was further explored by stripping the coating off part way through fatigue testing, revealing a delay in the onset of substrate damage with more fatigue resistant coatings but no benefit with coatings with inadequate properties. Finally, the results indicate that compressive residual stress and adequate load bearing capability of the coating (both controlled by torch and deposition parameters) delay onset of substrate damage, enabling fatigue credit of the coated component.« less

  5. Harnessing Macroscopic Forces in Catalysis

    DTIC Science & Technology

    2009-11-09

    that macroscopic deformation of an elastomeric support could result in molecular deformation of embedded, stress-bearing catalysts and influence their... elastomeric support could result in molecular deformation of embedded, stress-bearing catalysts and influence their reactivity. The focus was on the...a mechanocatalyst. Our Specific Aims were: Specific Aim 1. Synthesize elastomeric organogels and bulk rubbers with embedded, stress-bearing

  6. Study of metallic powder behavior in very low pressure plasma spraying (VLPPS) — Application to the manufacturing of titanium–aluminum coatings

    SciTech Connect

    Vautherin, B.; Planche, M.-P.; Montavon, G.; Lapostolle, F.; Quet, A.; Bianchi, L.

    2015-08-28

    In this study, metallic materials made of aluminum and titanium were manufactured implementing very low pressure plasma spraying (VLPPS). Aluminum was selected at first as a demonstrative material due to its rather low vaporization enthalpy (i.e., 381.9 kJ·mol⁻¹). Developments were then carried out with titanium which exhibits a higher vaporization enthalpy (i.e., 563.6 kJ·mol⁻¹). Optical emission spectroscopy (OES) was implemented to analyze the behavior of each solid precursor (metallic powders) when it is injected into the plasma jet under very low pressure (i.e., in the 150 Pa range). Besides, aluminum, titanium and titanium–aluminum coatings were deposited in the same conditions implementing a stick-cathode plasma torch operated at 50 kW, maximum power. Coating phase compositions were identified by X-Ray Diffraction (XRD). Coating elementary compositions were quantified by Glow Discharge Optical Emission Spectroscopy (GDOES) and Energy Dispersive Spectroscopy (EDS) analyses. The coating structures were observed by Scanning Electron Microscopy (SEM). The coating void content was determined by Ultra-Small Angle X-ray Scattering (USAXS). The coatings exhibit a two-scale structure corresponding to condensed vapors (smaller scale) and solidified areas (larger scale). Titanium–aluminum sprayed coatings, with various Ti/Al atomic ratios, are constituted of three phases: metastable α-Ti, Al and metastable α₂-Ti₃Al. This latter is formed at elevated temperature in the plasma flow, before being condensed. Its rather small fraction, impeded by the rather small amount of vaporized Ti, does not allow modifying however the coating hardness.

  7. Wear and Corrosion Behaviors of FeCrBSiNbW Amorphous/Nanocrystalline Coating Prepared by Arc Spraying Process

    NASA Astrophysics Data System (ADS)

    Cheng, J. B.; Wang, Z. H.; Xu, B. S.

    2012-09-01

    FeCrBSiNbW coatings were synthesized using robotically manipulating twin wires arc spraying system. The microstructure and mechanical properties of the coating were characterized. The coating has a laminated structure, and its porosity is 2.8%. The microstructure of the coating consists of amorphous and α-(Fe,Cr) nanocrystalline. The nanocrystalline grains with a scale of 20-75 nm are homogenously dispersed in amorphous matrix. The results show that FeCrBSiNbW coating has excellent wear and corrosion resistance. The wear resistance of the coating is about 4.6 times higher than that of 3Cr13 coating under the same testing condition. In 3.5% NaCl aqueous solution, the amorphous/nanocrystalline coating presents lower I corr values in polarization curves and higher fitted R t values in EIS plots than that of the 0Cr18Ni9 coating (chemical composition by EDAX analysis: C1.07-O12.38-Si0.49-Cr15.18-Mn0.89-Ni7.09-Fe62.24 at.%).

  8. Thermal Shock Behavior of Air Plasma Sprayed CoNiCrAlY/YSZ Thermal Barrier Coatings

    NASA Astrophysics Data System (ADS)

    Liu, Zi Wei; Wu, Wei; Hua, Jia Jie; Lin, Chu Cheng; Zheng, Xue Bin; Zeng, Yi

    2014-07-01

    The structural changes and failure mechanism of thermal barrier coatings (TBCs) during thermal shock cycling were investigated. TBCs consisting of CoNiCrAlY bond coat and partially yttria-stabilized zirconia (YSZ) top coat were deposited by atmospheric plasma spraying (APS) on a nickel-based alloy substrate and its thermal shock resistance performance was evaluated. TBCs were heated at 1100°C for 15 min followed by cold water quenching to ambient temperature. Microstructural evaluation and elemental analysis of TBCs were performed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), respectively. The crack features of YSZ coatings in TBCs during thermal shock cycling, including those of horizontal (parallel to the substrate) and vertical cracks (perpendicular to the substrate), were particularly investigated by means of SEM and image analysis. Results show that horizontal and vertical cracks have different influences on the thermal shock resistance of the coatings. Horizontal cracks that occur at the interface of YSZ and thermally growth oxidation (TGO) cause partial or large-area spalling of coatings. When vertical and horizontal cracks encounter, network segments are formed which lead to partial spalling of the coatings.

  9. The corrosion behavior and microstructure of high-velocity oxy-fuel sprayed nickel-base amorphous/nanocrystalline coatings

    NASA Astrophysics Data System (ADS)

    Dent, A. H.; Horlock, A. J.; McCartney, D. G.; Harris, S. J.

    1999-09-01

    The corrosion characteristics of two Ni-Cr-Mo-B alloy powders sprayed by the high-velocity oxy-fuel (HVOF) process have been studied using potentiodynamic and potentiostatic corrosion analysis in 0.5 M H2SO4. The deposits were also microstructurally characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM) (utilizing both secondary electron and backscattered electron modes), and transmission electron microscopy (TEM). Results from the microstructural examination of the two alloys have revealed a predominantly amorphous/nanocrystalline face centered cubic (fcc) matrix containing submicron boride precipitates as well as regions of martensitically transformed laths. Apparent recrystallization of the amorphous matrix has also been observed in the form of cellular crystals with a fcc structure. The oxide stringers observed at splat boundaries were found to be columnar grained α-Cr2O3, though regions of the spinel oxide NiCr2O4 with a globular morphology were also observed. The coatings of the two alloys exhibited comparable resistance to corrosion in 0.5 M H2SO4, as revealed by potentiodynamic tests. They both had rest potentials approximately equal to -300 mV saturated calomel electrode (SCE) and passive region current densities of ˜1 mA/cm2. Microstructural examination of samples tested potentiostatically revealed the prevalence of degradation at splat boundaries, especially those where significant oxidation of the deposit occurred.

  10. Oxidation Behavior of NiAl-TiB2 Coatings Prepared by Electrothermal Explosion Ultrahigh Speed Spraying

    NASA Astrophysics Data System (ADS)

    Hou, Shixiang; Liu, Zongde; Liu, Dongyu; Ma, Yimin

    The electro-thermal explosion ultrahigh speed spraying technology was employed to prepare the NiAl coatings with 0, 10, and 20 wt.% TiB2 on the Ni-based super-alloy substrate. The Microstructure, phase structure, and hardness of coatings were analyzed by scanning electron microscopy with energy dispersive X-ray spectrometry, X-ray diffraction, and Vickers micro-hardness tester, respectively. The results showed that the coatings had dense microstructure with submicron grains. The addition of TiB2 as a particulate reinforcement increased the hardness of NiAl. The isothermal oxidation test of coatings at 1000 °C for 140 h in air was investigated. The results showed that the oxidation resistance of NiAl coatings was higher than that of NiAl-TiB2 coatings at high temperature. The oxides and morphologies of the above coatings were investigated. The Al2O3 was formed on NiAl coating surface, while Al2O3 and TiO2 were formed on NiAl-TiB2 coating surface after oxidation.

  11. Mechanical and tribological behavior of red clay ceramic tiles coated with fly ash powders by thermal spraying technique.

    NASA Astrophysics Data System (ADS)

    Peña-Rodríguez, G.; Dulce-Moreno, H.; Daza-Ramírez, J.; Orozco-Hernández, S.; Vargas-Galvis, F.

    2017-01-01

    The mechanical and tribological performance of red clay ceramic tiles uncoated and coated by oxy-fuel thermal spraying process from fly ash powders was evaluated. The ceramic tile substrates were manufactured by uniaxial pressing at 26.17 bar pressure, and sintered at 1100 °C. The coating thickness was determined based on the number of projection-cycles oxyacetylene flame over substrate. Coal fly ash coatings were deposited, with average thickness of 56.18±12.18 μm, 180.42±20.32 μm, and 258.26±25.88μm. The mechanical resistance to bending and wear by abrasion deep, were studied using ISO 10545-4 standards and ISO 10545-6 respectively; adhesion was measured using Elcometer equipment Type III according to ASTM D-4541-02 and the average roughness (Ra) was found according to ASTM standard D7127-13, using the profilometer Mitutoyo SJ 201. The surface morphology presented the heterogeneous molten or semi molten splats with average size of 35.262±3.48 micrometers with good adhesion, justifying increased mechanical resistance to bending by 5%, as well as wear by abrasion deep. These results contribute to the development of ceramic products with added value, to be used in various technological applications.

  12. Abrasive Wear Behavior of WC Reinforced Ni-BASED Composite Coating Sprayed and Fused by Oxy-Acetylene Flame

    NASA Astrophysics Data System (ADS)

    Wang, Qun; Chen, Zhenhua; Ding, Zhang Xiong; Chen, Ding

    Microstructure of WC reinforced Ni-based self-fluxing alloy composite coating sprayed and fused by oxy-acetylene flame was investigated by scanning electron microscopy and energy dispersive X-ray Spectrometry, X-ray diffraction, and transmission electron microscopy. The wear performance of the coating was studied by a MLS-225 wet sand rubber wheel abrasive wear tester at various loads and sizes of abrasive particles. Also, the wear resistance of the coating was compared with uncoated ASTM1020 steel. The results indicated that the coating is bonded metallurgically to the substrate and has a homogeneous microstructure composed of both coarse WC and fine carbide and boride grains such as Cr7C3, Cr23C6, and Ni2B which disperse uniformly in the matrix of γ-Ni solid solution and Ni3B. The worn mass loss of the coating and ASTM1020 steel both increased with the load and size of abrasive particles, also, the coating has exhibited excellent abrasive wear resistance compared with ASTM1020 steel.

  13. A comparative study on solid particle erosion behavior of plasma sprayed Cr2O3 coatings on 410 grade steel

    NASA Astrophysics Data System (ADS)

    Sreenivas Rao, K. V.; Girisha, K. G.; Eswar, Sushruta

    2016-09-01

    In the present investigation chromium oxide (Cr2O3) powder particles were used to deposit on 410 martensitic steel. Ni-Cr was used as bond coat. Erosion studies were directed on uncoated and also plasma sprayed steel examples at room temperature. The Erosion analyses were done utilizing an air-jet erosion test rig at a speed of 30 m/s by varying stand-off distance as per ASTM G-76. The stand-off distance considered were 10mm, 20mm, 30mm & 40mm. Silica sand particles of size 312μm was used as erodent. The surface morphologies were characterized using Scanning electron microscope (SEM) and presence of coating material was confirmed using energy dispersive X-ray analyzer (EDS). Vickers micro harness test was performed on surface of coated and un-coated substrates. It was observed that Cr2O3 Coated specimen exhibits better Erosion resistance when contrasted with uncoated substrates because of its enhanced property like micro hardness.

  14. Foliar spray banding characteristics

    Treesearch

    A.R. Womac; C.W. Smith; Joseph E. Mulrooney

    2004-01-01

    Foliar spray banding was explored as a means of reducing peticide use compared to broadcast applications. Barious geometric spray patterns and delivery angles of foliar spray bands were investigated to increase spray deposits in a crop row at a constant spray rate of 94 L/ha. Wind-free laboratory results indicated that a banded application using three 65° hollow-cone...

  15. Spray atomization and combustion

    NASA Technical Reports Server (NTRS)

    Faeth, G. M.

    1986-01-01

    New theoretical and experimental methods for studying sprays are reviewed. Common methods to analyze dilute sprays are described and used to interpret recent measurements of the structure of dilute sprays and related dispersed turbulent jets. Particle-laden jets, nonevaporating, evaporating, and combusting sprays, and noncondensing and condensing bubbly jets are examined and used to initially evaluate current analytical methods for a wide range of conditions. Dense sprays are briefly discussed.

  16. Scaling of macroscopic superpositions close to a quantum phase transition

    NASA Astrophysics Data System (ADS)

    Abad, Tahereh; Karimipour, Vahid

    2016-05-01

    It is well known that in a quantum phase transition (QPT), entanglement remains short ranged [Osterloh et al., Nature (London) 416, 608 (2005), 10.1038/416608a]. We ask if there is a quantum property entailing the whole system which diverges near this point. Using the recently proposed measures of quantum macroscopicity, we show that near a quantum critical point, it is the effective size of macroscopic superposition between the two symmetry breaking states which grows to the scale of system size, and its derivative with respect to the coupling shows both singular behavior and scaling properties.

  17. Macroscopic quantum electrodynamics and duality.

    PubMed

    Buhmann, Stefan Yoshi; Scheel, Stefan

    2009-04-10

    We discuss under what conditions the duality between electric and magnetic fields is a valid symmetry of macroscopic quantum electrodynamics. It is shown that Maxwell's equations in the absence of free charges satisfy duality invariance on an operator level, whereas this is not true for Lorentz forces and atom-field couplings in general. We prove that derived quantities such as Casimir forces, local-field corrected decay rates, as well as van der Waals potentials are invariant with respect to a global exchange of electric and magnetic quantities. This exact symmetry can be used to deduce the physics of new configurations on the basis of already established ones.

  18. Matching Microscopic and Macroscopic Responses in Glasses

    NASA Astrophysics Data System (ADS)

    Baity-Jesi, M.; Calore, E.; Cruz, A.; Fernandez, L. A.; Gil-Narvion, J. M.; Gordillo-Guerrero, A.; Iñiguez, D.; Maiorano, A.; Marinari, E.; Martin-Mayor, V.; Monforte-Garcia, J.; Muñoz-Sudupe, A.; Navarro, D.; Parisi, G.; Perez-Gaviro, S.; Ricci-Tersenghi, F.; Ruiz-Lorenzo, J. J.; Schifano, S. F.; Seoane, B.; Tarancon, A.; Tripiccione, R.; Yllanes, D.; Janus Collaboration

    2017-04-01

    We first reproduce on the Janus and Janus II computers a milestone experiment that measures the spin-glass coherence length through the lowering of free-energy barriers induced by the Zeeman effect. Secondly, we determine the scaling behavior that allows a quantitative analysis of a new experiment reported in the companion Letter [S. Guchhait and R. Orbach, Phys. Rev. Lett. 118, 157203 (2017)]., 10.1103/PhysRevLett.118.157203 The value of the coherence length estimated through the analysis of microscopic correlation functions turns out to be quantitatively consistent with its measurement through macroscopic response functions. Further, nonlinear susceptibilities, recently measured in glass-forming liquids, scale as powers of the same microscopic length.

  19. Matching Microscopic and Macroscopic Responses in Glasses.

    PubMed

    Baity-Jesi, M; Calore, E; Cruz, A; Fernandez, L A; Gil-Narvion, J M; Gordillo-Guerrero, A; Iñiguez, D; Maiorano, A; Marinari, E; Martin-Mayor, V; Monforte-Garcia, J; Muñoz-Sudupe, A; Navarro, D; Parisi, G; Perez-Gaviro, S; Ricci-Tersenghi, F; Ruiz-Lorenzo, J J; Schifano, S F; Seoane, B; Tarancon, A; Tripiccione, R; Yllanes, D

    2017-04-14

    We first reproduce on the Janus and Janus II computers a milestone experiment that measures the spin-glass coherence length through the lowering of free-energy barriers induced by the Zeeman effect. Secondly, we determine the scaling behavior that allows a quantitative analysis of a new experiment reported in the companion Letter [S. Guchhait and R. Orbach, Phys. Rev. Lett. 118, 157203 (2017)].PRLTAO0031-900710.1103/PhysRevLett.118.157203 The value of the coherence length estimated through the analysis of microscopic correlation functions turns out to be quantitatively consistent with its measurement through macroscopic response functions. Further, nonlinear susceptibilities, recently measured in glass-forming liquids, scale as powers of the same microscopic length.

  20. Corrosion Behavior of Thermally Sprayed NiCrBSi Coating on 16MnR Low-Alloy Steel in KOH Solution

    NASA Astrophysics Data System (ADS)

    Zeng, Q.; Sun, J.; Emori, W.; Jiang, S. L.

    2016-05-01

    NiCrBSi coatings were selected as protective material and air plasma-sprayed on 16MnR low-alloy steel substrates. Corrosion behavior of 16MnR substrates and NiCrBSi coatings in KOH solution were evaluated by polarization resistance ( R p), potentiodynamic polarization curves, electrochemical impedance spectroscopy, and immersion corrosion tests. Electrolytes were solutions with different KOH concentrations. NiCrBSi coating showed superior corrosion resistance in KOH solution compared with the 16MnR. Corrosion current density of 16MnR substrate was 1.7-13.0 times that of NiCrBSi coating in the given concentration of KOH solution. By contrast, R p of NiCrBSi coating was 1.2-8.0 times that of the substrate, indicating that the corrosion rate of NiCrBSi coating was much lower than that of 16MnR substrate. Capacitance and total impedance value of NiCrBSi coating were much higher than those of 16MnR substrate in the same condition. This result indicates that corrosion resistance of NiCrBSi coating was better than that of 16MnR substrate, in accordance with polarization results. NiCrBSi coatings provided good protection for 16MnR substrate in KOH solution. Corrosion products were mainly Ni/Fe/Cr oxides.

  1. Furnace Cyclic Behavior of Plasma-Sprayed Zirconia-Yttria and Multi-Component Rare Earth Oxide Doped Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Nesbitt, James A.; McCue, Terry R.; Barrett, Charles A.; Miller, Robert A.

    2002-01-01

    Ceramic thermal barrier coatings will play an increasingly important role in advanced gas turbine engines because of their ability to enable further increases in engine temperatures. However, the coating performance and durability become a major concern under the increasingly harsh thermal cycling conditions. Advanced zirconia- and hafnia-based cluster oxide thermal barrier coatings with lower thermal conductivity and improved thermal stability are being developed using a high-heat-flux laser-rig based test approach. Although the new composition coatings were not yet optimized for cyclic durability, an initial durability screening of numerous candidate coating materials was carried out using conventional furnace cyclic tests. In this paper, furnace thermal cyclic behavior of the advanced plasma-sprayed zirconia-yttria-based thermal barrier coatings that were co-doped with multi-component rare earth oxides was investigated at 1163 C using 45 min hot cycles. The ceramic coating failure mechanisms were studied by using scanning electron microscopy combined with X-ray diffraction phase analysis after the furnace tests. The coating cyclic lifetime will be discussed in relation to coating phase structures, total dopant concentrations, and other properties.

  2. Relationship Between pH and Electrochemical Corrosion Behavior of Thermal-Sprayed Ni-Al-Coated Q235 Steel in Simulated Soil Solutions

    NASA Astrophysics Data System (ADS)

    Wei, Wei; Wu, Xin-qiang; Ke, Wei; Xu, Song; Feng, Bing; Hu, Bo-tao

    2017-09-01

    Electrochemical corrosion behavior of a thermal-sprayed Ni-Al-coated Q235 steel was investigated in the simulated soil solutions at different pH values using measurements of potentiodynamic polarization curves and electrochemical impedance spectroscopy as well as surface analyses including x-ray diffraction analysis, scanning electron microscope equipped with an energy-dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy. The results showed that the corrosion resistance of the Ni-Al-coated Q235 steel was dependent on the pH of the test solution. From pH = 3.53 to pH = 4.79, the corrosion resistance of the coated steel increased rapidly. In the pH range from 4.79 to 12.26, the corrosion resistance exhibited no significant change. At pH 13.25, the corrosion resistance of the sample was found to decrease. The calculated corrosion rate of Ni-Al-coated Q235 steel was lower than that of the uncoated Q235 steel and galvanized steel in all the test solutions. Over a wide range of pH values, the Ni-Al-coated Q235 steel exhibited extremely good corrosion resistance. The experimental data together with the potential-pH diagrams provided a basis for a detailed discussion of the related corrosion mechanisms of the coated steel.

  3. A Comparative Study of Cyclic Oxidation and Sulfates-Induced Hot Corrosion Behavior of Arc-Sprayed Ni-Cr-Ti Coatings at Moderate Temperatures

    NASA Astrophysics Data System (ADS)

    Guo, Wenmin; Wu, Yuping; Zhang, Jianfeng; Hong, Sheng; Chen, Liyan; Qin, Yujiao

    2015-06-01

    The cyclic oxidation and sulfates-induced hot corrosion behaviors of a Ni-43Cr-0.3Ti arc-sprayed coating at 550-750 °C were characterized and compared in this study. In general, all the oxidation and hot corrosion kinetic curves of the coating followed a parabolic law, i.e., the weight of the specimens showed a rapid growth initially and then reached the gradual state. However, the initial stage of the hot corrosion process was approximately two times longer than that of the oxidation process, indicating a longer preparation time required for the formation of a protective scale in the former process. At 650 °C, the parabolic rate constant for the hot corrosion was 7.2 × 10-12 g2/(cm4·s), approximately 1.7 times higher than that for the oxidation at the same temperature. The lower parabolic rate constant for the oxidation was mainly attributed to the formation of a protective oxide scale on the surface of corroded specimens, which was composed of a mixture of NiO, Cr2O3, and NiCr2O4. However, as the liquid molten salts emerged during the hot corrosion, these protective oxides would be dissolved and the coating was corrupted acceleratedly.

  4. Numerical Simulation and Experimental Characterization of a Binary Aluminum Alloy Spray - Application to the Spray Rolling Process

    SciTech Connect

    S. B. Johnson; J.-P. Delplanque; Y. Lin; Y. Zhou; E. J. Lavernia; K. M. McHugh

    2005-02-01

    A stochastic, droplet-resolved model has been developed to describe the behavior of a binary aluminum alloy spray during the spray-rolling process. In this process, a molten aluminum alloy is atomized and the resulting spray is depostied on the rolls of a twin-roll caster to produce aluminum strip. The one-way coupled spray model allows the prediction of spray characteristics such as enthalph and solid fraction, and their distribution between the nozzle and the depostion surface. This paper outlines the model development and compares the predicted spray dynamics to PDI measurements performed in a controlled configuration. Predicted and measured droplet velocity and size distributions are presented for two points along the spray centerline along with predicted spray averaged specific enthalph and solid fraction curves.

  5. Quantum correlations of lights in macroscopic environments

    NASA Astrophysics Data System (ADS)

    Sua, Yong Meng

    This dissertation presents a detailed study in exploring quantum correlations of lights in macroscopic environments. We have explored quantum correlations of single photons, weak coherent states, and polarization-correlated/polarization-entangled photons in macroscopic environments. These included macroscopic mirrors, macroscopic photon number, spatially separated observers, noisy photons source and propagation medium with loss or disturbances. We proposed a measurement scheme for observing quantum correlations and entanglement in the spatial properties of two macroscopic mirrors using single photons spatial compass state. We explored the phase space distribution features of spatial compass states, such as chessboard pattern by using the Wigner function. The displacement and tilt correlations of the two mirrors were manifested through the propensities of the compass states. This technique can be used to extract Einstein-Podolsky-Rosen correlations (EPR) of the two mirrors. We then formulated the discrete-like property of the propensity P b(m,n), which can be used to explore environmental perturbed quantum jumps of the EPR correlations in phase space. With single photons spatial compass state, the variances in position and momentum are much smaller than standard quantum limit when using a Gaussian TEM 00 beam. We observed intrinsic quantum correlations of weak coherent states between two parties through balanced homodyne detection. Our scheme can be used as a supplement to decoy-state BB84 protocol and differential phase-shift QKD protocol. We prepared four types of bipartite correlations +/- cos2(theta1 +/- theta 2) that shared between two parties. We also demonstrated bits correlations between two parties separated by 10 km optical fiber. The bits information will be protected by the large quantum phase fluctuation of weak coherent states, adding another physical layer of security to these protocols for quantum key distribution. Using 10 m of highly nonlinear

  6. Indirect measurement of interfacial melting from macroscopic ice observations.

    PubMed

    Saruya, Tomotaka; Kurita, Kei; Rempel, Alan W

    2014-06-01

    Premelted water that is adsorbed to particle surfaces and confined to capillary regions remains in the liquid state well below the bulk melting temperature and can supply the segregated growth of ice lenses. Using macroscopic measurements of ice-lens initiation position in step-freezing experiments, we infer how the nanometer-scale thicknesses of premelted films depend on temperature depression below bulk melting. The interfacial interactions between ice, liquid, and soda-lime glass particles exhibit a power-law behavior that suggests premelting in our system is dominated by short-range electrostatic forces. Using our inferred film thicknesses as inputs to a simple force-balance model with no adjustable parameters, we obtain good quantitative agreement between numerical predictions and observed ice-lens thickness. Macroscopic observations of lensing behavior have the potential as probes of premelting behavior in other systems.

  7. The SEL macroscopic modeling code

    NASA Astrophysics Data System (ADS)

    Glasser, A. H.; Tang, X. Z.

    2004-12-01

    The SEL (Spectral ELement) macroscopic modeling code for magnetically confined plasma combines adaptive spectral element spatial discretization and nonlinearly implicit time stepping via Newton's method on massively parallel computers. Static condensation is implemented to construct the Shur complement of the Jacobian matrix, which greatly accelerates the linear system solution and distinguishes itself from conventional Newton-Krylov schemes. Grid alignment with the evolving magnetic field, implemented with a variational principle, is a key component of grid adaptation in SEL, and is critical to toroidal plasma applications. Results of 2D magnetic reconnection are shown to illustrate the accuracy and efficiency of the parallel algorithms built on the Portable, Extensible Toolkits for Scientific Computing (PETSC) framework.

  8. Macroscopic dynamics of cancer growth

    NASA Astrophysics Data System (ADS)

    Menchón, S. A.; Condat, C. A.

    2007-04-01

    Macroscopic modeling is used to describe various aspects of cancer growth. A recently proposed “dysnamical exponent” hypothesis is critically examined in the context of the angiogenic development. It is also shown that the emergence of necroses facilitates the growth of avascular tumors; the model yields an excellent fit to available experimental data, allowing for the determination of growth parameters. Finally, the global effects of an applied antitumoral immunotherapy are investigated. It is shown that, in the long run, the application of a therapeutical course leads to bigger tumors by weakening the intraspecific competition between surviving viable cancer cells. The strength of this model lies in its simplicity and in the amount of information that can be gleaned using only very general ideas.

  9. Isothermal Oxidation Behavior of VC and Columnar Structured Thermal Barrier Coatings Deposited by Suspension Plasma Spray Technology

    NASA Astrophysics Data System (ADS)

    Li, Xiaolong; Yang, Qi; Huang, Xiao; Tang, Zhaolin

    2015-08-01

    The effects of different thermal barrier coating (TBC) top coat structures and substrate alloys on the isothermal oxidation behaviors of TBC systems were investigated at 1080 °C in lab air. The tested TBC systems consisted of two nickel-based superalloy substrates (CMSX-4 and IN738LC), a platinum aluminide bond coat and two 8YSZ top coats (vertical cracked and columnar structured). Samples with IN738LC substrate demonstrated longer isothermal oxidation lives than the counterparts with CMSX-4 substrate. Outward refractory elemental diffusion in coating systems with CMSX-4 substrate and void formation at the interface between thermally grown oxide and bond coat was found to be responsible for the early failure of TBCs. Columnar structured YSZ top coat seemed to provide better protection of the bond coating and substrate, marginally delaying the failure of the both coating systems with IN738LC and CMSX-4.

  10. Hair spray poisoning

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/002705.htm Hair spray poisoning To use the sharing features on this page, please enable JavaScript. Hair spray poisoning occurs when someone breathes in (inhales) ...

  11. Triamcinolone Nasal Spray

    MedlinePlus

    ... itchy nose and itchy, watery eyes caused by hay fever or other allergies. Triamcinolone nasal spray should not ... germs.Triamcinolone nasal spray controls the symptoms of hay fever and allergies but does not cure these conditions. ...

  12. Failure behavior of plasma-sprayed HAp coating on commercially pure titanium substrate in simulated body fluid (SBF) under bending load.

    PubMed

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

    2012-11-01

    Four point bending tests with acoustic emission (AE) monitoring were conducted for evaluating failure behavior of the plasma-sprayed hydroxyapatite (HAp) top coat on commercially pure titanium (cp-Ti) plate with and without mixed HAp/Ti bond coat. Effect of immersion in simulated body fluid (SBF) on failure behavior of the coated specimen was also investigated by immersing the specimen in SBF. The AE patterns obtained from the bending test of the HAp coating specimens after a week immersion in SBF clearly showed the earlier stage of delamination and spallation of the coating layer compared to those without immersion in SBF. It was also found that the bond coating improved failure resistance of the HAp coating specimen compared to that without the bond coat. Four point bend fatigue tests under ambient and SBF environments were also conducted with AE monitoring during the entire fatigue test for investigating the influence of SBF environment on fatigue failure behavior of the HAp coating specimen with the mixed HAp/Ti bond coat. The specimens tested at a stress amplitude of 120 MPa under both ambient and SBF environments could survive up to 10⁷ cycles without spallation of HAp coating layer. The specimens tested under SBF environment and those tested under ambient environment after immersion in SBF showed shorter fatigue life compared to those tested under ambient environment without SBF immersion. Micro-cracks nucleated in the coating layer in the early stage of fatigue life and then propagated into the cp-Ti substrate in the intermediate stage, which unstably propagated to failure in the final stage. It was found from the XRD analysis that the dissolution of the co-existing phases and the precipitation of the HAp phase were taken place during immersion in SBF. During this process, the co-existing phases disappeared from the coating layer and the HAp phase fully occupied the coating layer. The degradation of bending strength and fatigue life of the HAp coating

  13. Azelastine Nasal Spray

    MedlinePlus

    ... and replace with the pump unit. Prime the delivery system (pump unit) with four sprays or until a fine mist appears. If 3 days or more have elapsed since your last use of the nasal spray, reprime the pump with two sprays or until a fine mist appears.

  14. Remotely controlled spray gun

    NASA Technical Reports Server (NTRS)

    Cunningham, William C. (Inventor)

    1987-01-01

    A remotely controlled spray gun is described in which a nozzle and orifice plate are held in precise axial alignment by an alignment member, which in turn is held in alignment with the general outlet of the spray gun by insert. By this arrangement, the precise repeatability of spray patterns is insured.

  15. Friction and Wear Behavior of Plasma-Sprayed Al2O3-13 wt.%TiO2 Coatings Under the Lubrication of Liquid Paraffin

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaoqin; An, Yulong; Hou, Guoliang; Zhou, Huidi; Chen, Jianmin

    2014-04-01

    Two types of ceramic composite coatings (denoted as N-AT13 coating and M-AT13 coating) were fabricated on 1Cr18Ni9Ti stainless steel substrate from ultra-fine and coarse Al2O3-13%TiO2 feedstocks by air plasma spraying. The friction and wear behavior of as-prepared coatings sliding against Al2O3 and stainless steel balls under the lubrication of liquid paraffin was evaluated with an SRV friction and wear tester (Optimol, Germany). The fractured and worn surfaces of the coatings were observed using a scanning electron microscope and a field-emission scanning electron microscope; and the wear mechanisms of the coatings were discussed based on scanning electron microscopic analysis and energy dispersive spectrometric analysis. Results show that N-AT13 coating possesses a unique microstructure and strong inter-splat bonding, thereby showing increased microhardness and bonding strength as well as much better friction-reduction and wear resistance than M-AT13 coating. Moreover, there exist differences in the wear mechanisms of N-AT13 and M-AT13 coatings which slide against ceramic and stainless steel balls under the lubrication of liquid paraffin. Namely, with the increase of normal load, the burnishing of N-AT13 coating coupled with Al2O3 ball is gradually transformed to grain-abrasion and deformation, while M-AT13 coating is dominated by grain-pullout and brittle fracture in the whole range of tested normal load.

  16. Experiments on the Distribution of Fuel in Fuel Sprays

    NASA Technical Reports Server (NTRS)

    Lee, Dana W

    1933-01-01

    The distribution of fuel in sprays for compression-ignition engines was investigated by taking high-speed spark photographs of fuel sprays reproduced under a wide variety of conditions, and also by injecting them against pieces of plasticine. A photographic study was made of sprays injected into evacuated chambers, into the atmosphere, into compressed air, and into transparent liquids. Pairs of identical sprays were injected counter to each other and their behavior analyzed. Small high velocity air jets were directed normally to the axes of fuel sprays, with the result that the envelope of spray which usually obscures the core was blown aside, leaving the core exposed on one side. The results showed that the distribution of the fuel within the sprays was very uneven.

  17. Investigations on the Behavior of HVOF and Cold Sprayed Ni-20Cr Coating on T22 Boiler Steel in Actual Boiler Environment

    NASA Astrophysics Data System (ADS)

    Bala, Niraj; Singh, Harpreet; Prakash, Satya; Karthikeyan, J.

    2012-01-01

    High temperature corrosion accompanied by erosion is a severe problem, which may result in premature failure of the boiler tubes. One countermeasure to overcome this problem is the use of thermal spray protective coatings. In the current investigation high velocity oxy-fuel (HVOF) and cold spray processes have been used to deposit commercial Ni-20Cr powder on T22 boiler steel. To evaluate the performance of the coatings in actual conditions the bare as well as the coated steels were subjected to cyclic exposures, in the superheater zone of a coal fired boiler for 15 cycles. The weight change and thickness loss data were used to establish kinetics of the erosion-corrosion. X-ray diffraction, surface and cross-sectional field emission scanning electron microscope/energy dispersive spectroscopy (FE-SEM/EDS) and x-ray mapping techniques were used to analyse the as-sprayed and corroded specimens. The HVOF sprayed coating performed better than its cold sprayed counterpart in actual boiler environment.

  18. Macroscopic and tunable nanoparticle superlattices

    SciTech Connect

    Zhang, Honghu; Wang, Wenjie; Mallapragada, Surya; Travesset, Alex; Vaknin, David

    2016-10-24

    In this paper, we describe a robust method to assemble nanoparticles into highly ordered superlattices by inducing aqueous phase separation of neutral capping polymers. Here we demonstrate the approach with thiolated polyethylene-glycol-functionalized gold nanoparticles (PEG-AuNPs) in the presence of salts (for example, K2CO3) in solutions that spontaneously migrate to the liquid–vapor interface to form a Gibbs monolayer. We show that by increasing salt concentration, PEG-AuNP monolayers transform from two-dimensional (2D) gas-like to liquid-like phase and eventually, beyond a threshold concentration, to a highly ordered hexagonal structure, as characterized by surface sensitive synchrotron X-ray reflectivity and grazing incidence X-ray diffraction. Furthermore, the method allows control of the inplane packing in the crystalline phase by varying the K2CO3 and PEG-AuNPs concentrations and the length of PEG. Using polymer-brush theory, we argue that the assembly and crystallization is driven by the need to reduce surface tension between PEG and the salt solution. Our approach of taking advantage of the phase separation of PEG in salt solutions is general (i.e., can be used with any nanoparticles) leads to high-quality macroscopic and tunable crystals. In conclusion, we discuss how the method can also be applied to the design of orderly 3D structures.

  19. Macroscopic characterisations of Web accessibility

    NASA Astrophysics Data System (ADS)

    Lopes, Rui; Carriço, Luis

    2010-12-01

    The Web Science framework poses fundamental questions on the analysis of the Web, by focusing on how microscopic properties (e.g. at the level of a Web page or Web site) emerge into macroscopic properties and phenomena. One research topic on the analysis of the Web is Web accessibility evaluation, which centres on understanding how accessible a Web page is for people with disabilities. However, when framing Web accessibility evaluation on Web Science, we have found that existing research stays at the microscopic level. This article presents an experimental study on framing Web accessibility evaluation into Web Science's goals. This study resulted in novel accessibility properties of the Web not found at microscopic levels, as well as of Web accessibility evaluation processes themselves. We observed at large scale some of the empirical knowledge on how accessibility is perceived by designers and developers, such as the disparity of interpretations of accessibility evaluation tools warnings. We also found a direct relation between accessibility quality and Web page complexity. We provide a set of guidelines for designing Web pages, education on Web accessibility, as well as on the computational limits of large-scale Web accessibility evaluations.

  20. Macroscopic and tunable nanoparticle superlattices

    DOE PAGES

    Zhang, Honghu; Wang, Wenjie; Mallapragada, Surya; ...

    2016-10-24

    In this paper, we describe a robust method to assemble nanoparticles into highly ordered superlattices by inducing aqueous phase separation of neutral capping polymers. Here we demonstrate the approach with thiolated polyethylene-glycol-functionalized gold nanoparticles (PEG-AuNPs) in the presence of salts (for example, K2CO3) in solutions that spontaneously migrate to the liquid–vapor interface to form a Gibbs monolayer. We show that by increasing salt concentration, PEG-AuNP monolayers transform from two-dimensional (2D) gas-like to liquid-like phase and eventually, beyond a threshold concentration, to a highly ordered hexagonal structure, as characterized by surface sensitive synchrotron X-ray reflectivity and grazing incidence X-ray diffraction. Furthermore,more » the method allows control of the inplane packing in the crystalline phase by varying the K2CO3 and PEG-AuNPs concentrations and the length of PEG. Using polymer-brush theory, we argue that the assembly and crystallization is driven by the need to reduce surface tension between PEG and the salt solution. Our approach of taking advantage of the phase separation of PEG in salt solutions is general (i.e., can be used with any nanoparticles) leads to high-quality macroscopic and tunable crystals. In conclusion, we discuss how the method can also be applied to the design of orderly 3D structures.« less

  1. Characterization of sprays

    NASA Technical Reports Server (NTRS)

    Chigier, N.; Mao, C.-P.

    1984-01-01

    It is pointed out that most practical power generation and propulsion systems involve the burning of different types of fuel sprays, taking into account aircraft propulsion, industrial furnaces, boilers, gas turbines, and diesel engines. There has been a lack of data which can serve as a basis for spray model development and validation. A major aim of the present investigation is to fill this gap. Experimental apparatus and techniques for studying the characteristics of fuel sprays are discussed, taking into account two-dimensional still photography, cinematography, holography, a laser diffraction particle sizer, and a laser anemometer. The considered instruments were used in a number of experiments, taking into account three different types of fuel spray. Attention is given to liquid fuel sprays, high pressure pulsed diesel sprays, and coal-water slurry sprays.

  2. Macroscopic superposition of ultracold atoms with orbital degrees of freedom

    SciTech Connect

    Garcia-March, M. A.; Carr, L. D.; Dounas-Frazer, D. R.

    2011-04-15

    We introduce higher dimensions into the problem of Bose-Einstein condensates in a double-well potential, taking into account orbital angular momentum. We completely characterize the eigenstates of this system, delineating new regimes via both analytical high-order perturbation theory and numerical exact diagonalization. Among these regimes are mixed Josephson- and Fock-like behavior, crossings in both excited and ground states, and shadows of macroscopic superposition states.

  3. From macroscopic yield criteria to atomic stresses in polymer glasses

    SciTech Connect

    MacNeill, David; Rottler, Joerg

    2010-01-15

    The relationship between macroscopic shear yield criteria and local stress distributions in deformed polymer glasses is investigated via molecular dynamics simulations on different scales of coarse-graining. Macroscopic shear stresses at the yield point obey a pressure-modified von Mises (pmvM) criterion for many different loading conditions and strain rates. Average local stresses in small volume elements obey the same yield criterion for volumes containing approx. 100 atoms or more. Qualitatively different behavior is observed on smaller scales: the average octahedral atomic shear stress has a simple linear relationship to hydrostatic pressure regardless of macroscopic stress state and failure mode. Local plastic events are identified through a threshold in the mean-squared nonaffine displacement and compared to the local stress state. We find that the pmvM criterion only predicts local yield events when stress and displacements are averaged over at least 100 atoms. By contrast, macroscopic shear yield criteria appear to lose their ability to predict plastic activity on the atomic scale.

  4. Links between microscopic and macroscopic fluid mechanics

    NASA Astrophysics Data System (ADS)

    Hoover, Wm. G.; Hoover, C. G.

    2003-01-01

    The microscopic and macroscopic versions of fluid mechanics differ qualitatively. Microscopic particles obey time-reversible ordinary differential equations. The resulting particle trajectories {q(t)} may be time-averaged or ensemble-averaged so as to generate field quantities corresponding to macroscopic variables. On the other hand, the macroscopic continuum fields described by fluid mechanics follow irreversible partial differential equations. Smooth particle methods bridge the gap separating these two views of fluids by solving the macroscopic field equations with particle dynamics that resemble molecular dynamics. Recently, nonlinear dynamics have provided some useful tools for understanding the relationship between the microscopic and macroscopic points of view. Chaos and fractals play key roles in this new understanding. Non-equilibrium phase-space averages look very different from their equilibrium counterparts. Away from equilibrium the smooth phase-space distributions are replaced by fractional-dimensional singular distributions that exhibit time irreversibility.

  5. Macroscopic Superpositions as Quantum Ground States

    NASA Astrophysics Data System (ADS)

    Dakić, Borivoje; Radonjić, Milan

    2017-09-01

    We study the question of what kind of a macroscopic superposition can(not) naturally exist as a ground state of some gapped local many-body Hamiltonian. We derive an upper bound on the energy gap of an arbitrary physical Hamiltonian provided that its ground state is a superposition of two well-distinguishable macroscopic "semiclassical" states. For a large class of macroscopic superposition states we show that the gap vanishes in the macroscopic limit. This in turn shows that preparation of such states by simple cooling to the ground state is not experimentally feasible and requires a different strategy. Our approach is very general and can be used to rule out a variety of quantum states, some of which do not even exhibit macroscopic quantum properties. Moreover, our methods and results can be used for addressing quantum marginal related problems.

  6. Macroscopic Quantum Phenomena from the Correlation, Coupling and Criticality Perspectives

    NASA Astrophysics Data System (ADS)

    Chou, C. H.; Hu, B. L.; Subaşi, Y.

    2011-12-01

    In this sequel paper we explore how macroscopic quantum phenomena can be measured or understood from the behavior of quantum correlations which exist in a quantum system of many particles or components and how the interaction strengths change with energy or scale, under ordinary situations and when the system is near its critical point. We use the nPI (master) effective action related to the Boltzmann-BBGKY / Schwinger-Dyson hierarchy of equations as a tool for systemizing the contributions of higher order correlation functions to the dynamics of lower order correlation functions. Together with the large N expansion discussed in our first paper [1] we explore 1) the conditions whereby an H-theorem is obtained, which can be viewed as a signifier of the emergence of macroscopic behavior in the system. We give two more examples from past work: 2) the nonequilibrium dynamics of N atoms in an optical lattice under the large Script N (field components), 2PI and second order perturbative expansions, illustrating how N and Script N enter in these three aspects of quantum correlations, coherence and coupling strength. 3) the behavior of an interacting quantum system near its critical point, the effects of quantum and thermal fluctuations and the conditions under which the system manifests infrared dimensional reduction. We also discuss how the effective field theory concept bears on macroscopic quantum phenomena: the running of the coupling parameters with energy or scale imparts a dynamical-dependent and an interaction-sensitive definition of 'macroscopia'.

  7. Quantitative characterization of diesel sprays using digital imaging techniques

    NASA Astrophysics Data System (ADS)

    Shao, J.; Yan, Y.; Greeves, G.; Smith, S.

    2003-07-01

    This paper presents the application of digital imaging and image processing techniques for the quantitative characterization of diesel sprays. An optically accessible, constant volume chamber was configured to allow direct photographic imaging of diesel sprays, which were generated from a six-hole nozzle in a non-evaporating and pressurized environment. A high-resolution CCD camera and a flash light source were used to capture the images of the sprays. Dedicated image processing software has been developed to quantify a set of macroscopic, characteristic parameters of the sprays including tip penetration, near-and far-field angles. The spray parameters produced using this software are compared with those obtained using manual methods. The results obtained under typical spray conditions demonstrate that the software is capable of producing more accurate, consistent and efficient results than the manual methods. An application of the imaging processing software to the characterization of diesel sprays for a valve covered orifice nozzle is also presented and discussed.

  8. Macroscopic theory of dark sector

    NASA Astrophysics Data System (ADS)

    Meierovich, Boris

    A simple Lagrangian with squared covariant divergence of a vector field as a kinetic term turned out an adequate tool for macroscopic description of the dark sector. The zero-mass field acts as the dark energy. Its energy-momentum tensor is a simple additive to the cosmological constant [1]. Space-like and time-like massive vector fields describe two different forms of dark matter. The space-like massive vector field is attractive. It is responsible for the observed plateau in galaxy rotation curves [2]. The time-like massive field displays repulsive elasticity. In balance with dark energy and ordinary matter it provides a four parametric diversity of regular solutions of the Einstein equations describing different possible cosmological and oscillating non-singular scenarios of evolution of the universe [3]. In particular, the singular big bang turns into a regular inflation-like transition from contraction to expansion with the accelerate expansion at late times. The fine-tuned Friedman-Robertson-Walker singular solution corresponds to the particular limiting case at the boundary of existence of regular oscillating solutions in the absence of vector fields. The simplicity of the general covariant expression for the energy-momentum tensor allows to analyse the main properties of the dark sector analytically and avoid unnecessary model assumptions. It opens a possibility to trace how the additional attraction of the space-like dark matter, dominating in the galaxy scale, transforms into the elastic repulsion of the time-like dark matter, dominating in the scale of the Universe. 1. B. E. Meierovich. "Vector fields in multidimensional cosmology". Phys. Rev. D 84, 064037 (2011). 2. B. E. Meierovich. "Galaxy rotation curves driven by massive vector fields: Key to the theory of the dark sector". Phys. Rev. D 87, 103510, (2013). 3. B. E. Meierovich. "Towards the theory of the evolution of the Universe". Phys. Rev. D 85, 123544 (2012).

  9. Cloud Macroscopic Organization: Order Emerging from Randomness

    NASA Technical Reports Server (NTRS)

    Yuan, Tianle

    2011-01-01

    Clouds play a central role in many aspects of the climate system and their forms and shapes are remarkably diverse. Appropriate representation of clouds in climate models is a major challenge because cloud processes span at least eight orders of magnitude in spatial scales. Here we show that there exists order in cloud size distribution of low-level clouds, and that it follows a power-law distribution with exponent gamma close to 2. gamma is insensitive to yearly variations in environmental conditions, but has regional variations and land-ocean contrasts. More importantly, we demonstrate this self-organizing behavior of clouds emerges naturally from a complex network model with simple, physical organizing principles: random clumping and merging. We also demonstrate symmetry between clear and cloudy skies in terms of macroscopic organization because of similar fundamental underlying organizing principles. The order in the apparently complex cloud-clear field thus has its root in random local interactions. Studying cloud organization with complex network models is an attractive new approach that has wide applications in climate science. We also propose a concept of cloud statistic mechanics approach. This approach is fully complementary to deterministic models, and the two approaches provide a powerful framework to meet the challenge of representing clouds in our climate models when working in tandem.

  10. Monte-Carlo Spray Cooling Model

    NASA Astrophysics Data System (ADS)

    Kreitzer, Paul J.; Kuhlman, John M.

    2010-01-01

    Spray cooling is a tremendously complex phenomenon that has yet to be completely and successfully modeled. This is due to the complexity of the detailed droplet impingement processes and the subsequent heat transfer process. Numerous assumptions must be made in order to accurately model spray behavior. Current computational limitations restrict CFD simulations to single droplet simulations. Additional complexity due to droplet interactions negates the possibility of combining multiple single droplet studies to represent the complete spray process. Therefore, a need has been established for the development of a comprehensive spray impingement simulation with adequate physical complexity to yield accurate results within a relatively short run time. The present work attempts to develop such a model using modeling assumptions from the best available literature, and to combine them into a single spray impingement simulation. Initial flow parameters that have been chosen include flow rate of 10 GPH with a velocity of 12 m/s and average droplet diameter of 48 μm. These values produce the following non-dimensional number ranges: We 100-1800, Re 200-4500, Oh 0.01-0.05. Numerical and experimental correlations have been identified that represent crater formation, splashing, film thickness, and droplet size and spatial flux distributions. A combination of these methods has resulted in an initial spray impingement simulation that is capable of simulating 100,000 drops or an actual simulation time of 0.0167 seconds. Comparisons of results from this code with experimental results show a similar trend in surface behavior.

  11. Rank distributions: A panoramic macroscopic outlook

    NASA Astrophysics Data System (ADS)

    Eliazar, Iddo I.; Cohen, Morrel H.

    2014-01-01

    This paper presents a panoramic macroscopic outlook of rank distributions. We establish a general framework for the analysis of rank distributions, which classifies them into five macroscopic "socioeconomic" states: monarchy, oligarchy-feudalism, criticality, socialism-capitalism, and communism. Oligarchy-feudalism is shown to be characterized by discrete macroscopic rank distributions, and socialism-capitalism is shown to be characterized by continuous macroscopic size distributions. Criticality is a transition state between oligarchy-feudalism and socialism-capitalism, which can manifest allometric scaling with multifractal spectra. Monarchy and communism are extreme forms of oligarchy-feudalism and socialism-capitalism, respectively, in which the intrinsic randomness vanishes. The general framework is applied to three different models of rank distributions—top-down, bottom-up, and global—and unveils each model's macroscopic universality and versatility. The global model yields a macroscopic classification of the generalized Zipf law, an omnipresent form of rank distributions observed across the sciences. An amalgamation of the three models establishes a universal rank-distribution explanation for the macroscopic emergence of a prevalent class of continuous size distributions, ones governed by unimodal densities with both Pareto and inverse-Pareto power-law tails.

  12. Rank distributions: a panoramic macroscopic outlook.

    PubMed

    Eliazar, Iddo I; Cohen, Morrel H

    2014-01-01

    This paper presents a panoramic macroscopic outlook of rank distributions. We establish a general framework for the analysis of rank distributions, which classifies them into five macroscopic "socioeconomic" states: monarchy, oligarchy-feudalism, criticality, socialism-capitalism, and communism. Oligarchy-feudalism is shown to be characterized by discrete macroscopic rank distributions, and socialism-capitalism is shown to be characterized by continuous macroscopic size distributions. Criticality is a transition state between oligarchy-feudalism and socialism-capitalism, which can manifest allometric scaling with multifractal spectra. Monarchy and communism are extreme forms of oligarchy-feudalism and socialism-capitalism, respectively, in which the intrinsic randomness vanishes. The general framework is applied to three different models of rank distributions-top-down, bottom-up, and global-and unveils each model's macroscopic universality and versatility. The global model yields a macroscopic classification of the generalized Zipf law, an omnipresent form of rank distributions observed across the sciences. An amalgamation of the three models establishes a universal rank-distribution explanation for the macroscopic emergence of a prevalent class of continuous size distributions, ones governed by unimodal densities with both Pareto and inverse-Pareto power-law tails.

  13. The Comparative Effect of Sugarcane Juice on the Abrasion-Corrosion Behavior of Fe-Cr-B Electric Arc Sprayed and Fe-Cr-C Weld Coatings

    NASA Astrophysics Data System (ADS)

    Buchanan, Vernon E.

    2012-02-01

    Abrasion-corrosion tests were conducted on two commonly Fe-Cr-C shielded metal arc welding (SMAW) hardfacings used in the sugar industry and an arc sprayed Fe-Cr-based coating. The tests were performed on a modified block-on-ring tester with the coatings sliding against compressed sugarcane fiber in the presence of abrasive slurry. The findings showed that, in the presence of sugarcane juice and sand slurry, the SMAW coatings had similar wear performance while the abrasive wear of the arc-sprayed coating was superior to the SMAW coatings. In the presence of a neutral solution, the material loss from the arc-sprayed coating was similar to that obtained in the sugarcane juice while the SMAW coatings showed a marked decrease; this demonstrated that the arc-sprayed coating was more desirable in an abrasive-corrosion environment. The study also showed that the resistance to material does not follow the expected trend, in which wear resistance increases with increasing hardness.

  14. Effect of Porosity Content of Arc-Sprayed Alloy 625 Skins on the Flexural Behavior of Nickel Foam Core Sandwich Structures

    NASA Astrophysics Data System (ADS)

    Salavati, S.; Pershin, L.; Coyle, T. W.; Mostaghimi, J.

    2015-01-01

    Metallic foam core sandwich structures have been of particular interest for engineering applications in recent decades because of their unique mechanical and physical properties. Thermal spraying techniques have been recently introduced as a novel low-cost method for production of these structures with complex shapes. One of the potential applications of the metallic foam core sandwich structures prepared by thermal spray techniques is as heat shield devices. Open porosity in the microstructure of the coating may allow the cooling efficiency of the heat shield to be improved through the film cooling phenomenon. A modified twin wire-arc spraying process was employed to deposit high temperature resistant alloy 625 coatings with a high percentage of the open porosity. The effect of skin porosity on the mechanical properties (flexural rigidity) of the sandwich structures was studied using a four-point bending test. It was concluded from the four-point bending test results that increase in the porosity content of the coatings leads to decrease in the flexural rigidity of the sandwich panels. The ductility of the porous and conventional arc-sprayed alloy 625 coatings was improved after heat treatment at 1100 °C for 3 h.

  15. Supersonic Particle Deposition (Cold Spray)

    DTIC Science & Technology

    2006-01-26

    SUPPLEMENTARY NOTES 26th Replacement of Hard Chrome and Cadmium Plating Program Review Meeting, January 24-26, 2006, San Diego, CA. Sponsored by SERDP...Spray Cu-W ( clad powder) 197 89-90 HRB Cold Spray Ta 256 21 HRC Cold Spray Ni 403 40-41 HRC Hardness of Various Cold Spray Coatings -Cold Spray

  16. A simplified model of aerosol removal by containment sprays

    SciTech Connect

    Powers, D.A. ); Burson, S.B. . Div. of Safety Issue Resolution)

    1993-06-01

    Spray systems in nuclear reactor containments are described. The scrubbing of aerosols from containment atmospheres by spray droplets is discussed. Uncertainties are identified in the prediction of spray performance when the sprays are used as a means for decontaminating containment atmospheres. A mechanistic model based on current knowledge of the physical phenomena involved in spray performance is developed. With this model, a quantitative uncertainty analysis of spray performance is conducted using a Monte Carlo method to sample 20 uncertain quantities related to phenomena of spray droplet behavior as well as the initial and boundary conditions expected to be associated with severe reactor accidents. Results of the uncertainty analysis are used to construct simplified expressions for spray decontamination coefficients. Two variables that affect aerosol capture by water droplets are not treated as uncertain; they are (1) [open quote]Q[close quote], spray water flux into the containment, and (2) [open quote]H[close quote], the total fall distance of spray droplets. The choice of values of these variables is left to the user since they are plant and accident specific. Also, they can usually be ascertained with some degree of certainty. The spray decontamination coefficients are found to be sufficiently dependent on the extent of decontamination that the fraction of the initial aerosol remaining in the atmosphere, m[sub f], is explicitly treated in the simplified expressions. The simplified expressions for the spray decontamination coefficient are given. Parametric values for these expressions are found for median, 10 percentile, and 90 percentile values in the uncertainty distribution for the spray decontamination coefficient. Examples are given to illustrate the utility of the simplified expressions to predict spray decontamination of an aerosol-laden atmosphere.

  17. Bear Spray Safety Program

    USGS Publications Warehouse

    Blome, C.D.; Kuzniar, R.L.

    2009-01-01

    A bear spray safety program for the U.S. Geological Survey (USGS) was officially initiated by the Firearms Safety Committee to address accident prevention and to promote personnel training in bear spray and its transportation, storage, and use for defense against wild animals. Used as part of a system including firearms, or used alone for those who choose not to carry a firearm, bear spray is recognized as an effective tool that can prevent injury in a wild animal attack.

  18. The development and application of an automatic boundary segmentation methodology to evaluate the vaporizing characteristics of diesel spray under engine-like conditions

    NASA Astrophysics Data System (ADS)

    Ma, Y. J.; Huang, R. H.; Deng, P.; Huang, S.

    2015-04-01

    Studying the vaporizing characteristics of diesel spray could greatly help to reduce engine emission and improve performance. The high-speed schlieren imaging method is an important optical technique for investigating the macroscopic vaporizing morphological evolution of liquid fuel, and pre-combustion constant volume combustion bombs are often used to simulate the high pressure and high temperature conditions occurring in diesel engines. Complicated background schlieren noises make it difficult to segment the spray region in schlieren spray images. To tackle this problem, this paper develops a vaporizing spray boundary segmentation methodology based on an automatic threshold determination algorithm. The methodology was also used to quantify the macroscopic characteristics of vaporizing sprays including tip penetration, near-field and far-field angles, and projected spray area and spray volume. The spray boundary segmentation methodology was realized in a MATLAB-based program. Comparisons were made between the spray characteristics obtained using the program method and those acquired using a manual method and the Hiroyasu prediction model. It is demonstrated that the methodology can segment and measure vaporizing sprays precisely and efficiently. Furthermore, the experimental results show that the spray angles were slightly affected by the injection pressure at high temperature and high pressure and under inert conditions. A higher injection pressure leads to longer spray tip penetration and a larger projected area and volume, while elevating the temperature of the environment can significantly promote the evaporation of cold fuel.

  19. New Tests of Macroscopic Local Realism

    NASA Astrophysics Data System (ADS)

    Reid, M. D.

    We show that quantum mechanics predicts an Einstein-Podolsky-Rosen paradox (EPR), and also a contradiction with local hidden variable theories, for photon number measurements which have limited resolving power, to the point of imposing an uncertainty in the photon number result which is macroscopic in absolute terms. We show how this can be interpreted as a failure of a new, very strong premise, called macroscopic local realism. We link this premise to the Schrodinger-cat paradox. Our proposed experiments ensure all fields incident on each measurement apparatus are macroscopic. We show that an alternative measurement scheme corresponds to balanced homodyne detection of quadrature phase amplitudes. The implication is that where either EPR correlations or failure of local realism is predicted for quadrature phase amplitude measurements, one can potentially perform a modified experiment which would lead to conclusions about the much stronger premise of macroscopic local realism.

  20. Sprayed cells and polyelectrolyte films for biomaterial functionalization: the influence of physical PLL-PGA film treatments on dental pulp cell behavior.

    PubMed

    Panayotov, Ivan V; Collart-Dutilleul, Pierre-Yves; Salehi, Hamideh; Martin, Marta; Végh, Attila; Yachouh, Jacques; Vladimirov, Boyan; Sipos, Péter; Szalontai, Balázs; Gergely, Csilla; Cuisinier, Frédéric J G

    2014-12-01

    Further development of biomaterials is expected as advanced therapeutic products must be compliant to good manufacturing practice regulations. A spraying method for building-up polyelectrolyte films followed by the deposition of dental pulp cells by spraying is presented. Physical treatments of UV irradiation and a drying/wetting process are applied to the system. Structural changes and elasticity modifications of the obtained coatings are revealed by atomic force microscopy and by Raman spectroscopy. This procedure results in thicker, rougher and stiffer film. The initially ordered structure composed of mainly α helices is transformed into random/β-structures. The treatment enhanced dental pulp cell adhesion and proliferation, suggesting that this system is promising for medical applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Transient heat transfer behavior of water spray evaporative cooling on a stainless steel cylinder with structured surface for safety design application in high temperature scenario

    NASA Astrophysics Data System (ADS)

    Aamir, Muhammad; Liao, Qiang; Hong, Wang; Xun, Zhu; Song, Sihong; Sajid, Muhammad

    2017-02-01

    High heat transfer performance of spray cooling on structured surface might be an additional measure to increase the safety of an installation against any threat caused by rapid increase in the temperature. The purpose of present experimental study is to explore heat transfer performance of structured surface under different spray conditions and surface temperatures. Two cylindrical stainless steel samples were used, one with pyramid pins structured surface and other with smooth surface. Surface heat flux of 3.60, 3.46, 3.93 and 4.91 MW/m2 are estimated for sample initial average temperature of 600, 700, 800 and 900 °C, respectively for an inlet pressure of 1.0 MPa. A maximum cooling rate of 507 °C/s was estimated for an inlet pressure of 0.7 MPa at 900 °C for structured surface while for smooth surface maximum cooling rate of 356 °C/s was attained at 1.0 MPa for 700 °C. Structured surface performed better to exchange heat during spray cooling at initial sample temperature of 900 °C with a relative increase in surface heat flux by factor of 1.9, 1.56, 1.66 and 1.74 relative to smooth surface, for inlet pressure of 0.4, 0.7, 1.0 and 1.3 MPa, respectively. For smooth surface, a decreasing trend in estimated heat flux is observed, when initial sample temperature was increased from 600 to 900 °C. Temperature-based function specification method was utilized to estimate surface heat flux and surface temperature. Limited published work is available about the application of structured surface spray cooling techniques for safety of stainless steel structures at very high temperature scenario such as nuclear safety vessel and liquid natural gas storage tanks.

  2. Titanium Dioxide Coatings Sprayed by a Water-Stabilized Plasma Gun (WSP) with Argon and Nitrogen as the Powder Feeding Gas: Differences in Structural, Mechanical and Photocatalytic Behavior

    NASA Astrophysics Data System (ADS)

    Ctibor, P.; Pala, Z.; Sedláček, J.; Štengl, V.; Píš, I.; Zahoranová, T.; Nehasil, V.

    2012-06-01

    Titanium dioxide coatings were sprayed by a water-stabilized plasma gun to form robust self-supporting bodies with a photocatalytically active surface. Agglomerated nanometric powder was used as a feedstock. In one case argon was used as a powder-feeding as well as coating-cooling gas whereas in the other case nitrogen was used. Stainless steel was used as a substrate and the coatings were released after the cooling. Over one millimeter thick self-supporting bodies were studied by XRD, HR-TEM, XPS, Raman spectroscopy, UV-VIS spectrophotometry and photocatalytic tests. Selected tests were done at the surface as well as at the bottom side representing the contact surface with the substrate during the spray process. Porosity was studied by image analysis on polished cross sections where also microhardness was measured. The dominant phase present in the sprayed samples was rutile, whereas anatase was only a minor component. The hydrogen content in the nitrogen-assisted coating was higher, but the character of the optical absorption edge remained the same for both samples. Photoelectron spectroscopy revealed differences in the character of the O1s peak between both samples. The photocatalytic activity was tested by decomposition of acetone at UV illumination, whereas also the end products—CO and CO2—were monitored. The nitrogen-assisted coating was revealed as a more efficient photocatalyst. Certain aspects of a thermal post-treatment on the coatings are discussed as well. Color and electrical conductivity are markedly changed at annealing at 760 °C, whereas only very small changes of the as-sprayed coating character correspond to annealing at 500 °C.

  3. Cold spray nozzle design

    DOEpatents

    Haynes, Jeffrey D.; Sanders, Stuart A.

    2009-06-09

    A nozzle for use in a cold spray technique is described. The nozzle has a passageway for spraying a powder material, the passageway having a converging section and a diverging section, and at least the diverging section being formed from polybenzimidazole. In one embodiment of the nozzle, the converging section is also formed from polybenzimidazole.

  4. Environmentally compatible spray cement

    SciTech Connect

    Loeschnig, P.

    1995-12-31

    Within the framework of a European research project, Heidelberger Zement developed a quickly setting and hardening binder for shotcrete, called Chronolith S, which avoids the application of setting accelerators. Density and strength of the shotcrete produced with this spray cement correspond to those of an unaccelerated shotcrete. An increased hazard for the heading team and for the environment, which may occur when applying setting accelerators, can be excluded here. Owing to the special setting properties of a spray cement, the process engineering for its manufacturing is of great importance. The treatment of a spray cement as a dry concrete with kiln-dried aggregates is possible without any problems. The use of a naturally damp pre-batched mixture is possible with Chronolith S but requires special process engineering; spray cement and damp aggregate are mixed with one another immediately before entering the spraying machinery.

  5. Microscopic reversibility and macroscopic irreversibility: A lattice gas model

    NASA Astrophysics Data System (ADS)

    Pérez-Cárdenas, Fernando C.; Resca, Lorenzo; Pegg, Ian L.

    2016-09-01

    We present coarse-grained descriptions and computations of the time evolution of a lattice gas system of indistinguishable particles, whose microscopic laws of motion are exactly reversible, in order to investigate how or what kind of macroscopically irreversible behavior may eventually arise. With increasing coarse-graining and number of particles, relative fluctuations of entropy rapidly decrease and apparently irreversible behavior unfolds. Although that behavior becomes typical in those limits and within a certain range, it is never absolutely irreversible for any individual system with specific initial conditions. Irreversible behavior may arise in various ways. We illustrate one possibility by replacing detailed integer occupation numbers at lattice sites with particle probability densities that evolve diffusively.

  6. Spray measurement technology: a review

    NASA Astrophysics Data System (ADS)

    Fansler, Todd D.; Parrish, Scott E.

    2015-01-01

    Sprays are among the most intellectually challenging and practically important topics in fluid mechanics. This paper reviews needs, milestones, challenges, and a broad array of techniques for spray measurement. In addition, tabular summaries provide cross-referenced entry points to the vast literature by organizing over 300 citations according to key spray phenomena, physical parameters and measurement techniques for each of the principal spray regions (nozzle internal flow, near-field spray-formation region, far-field developed spray, and spray-wall interaction). The article closes with perspectives on some current issues in spray research, including the cost and complexity of apparatus for spray physics and spray engineering, the need for simultaneous diagnostic measurements under application-relevant conditions, and the effective comparison of spray measurements and numerical simulations.

  7. Spray Rolling Aluminum Strip

    SciTech Connect

    Lavernia, E.J.; Delplanque, J-P; McHugh, K.M.

    2006-05-10

    Spray forming is a competitive low-cost alternative to ingot metallurgy for manufacturing ferrous and non-ferrous alloy shapes. It produces materials with a reduced number of processing steps, while maintaining materials properties, with the possibility of near-net-shape manufacturing. However, there are several hurdles to large-scale commercial adoption of spray forming: 1) ensuring strip is consistently flat, 2) eliminating porosity, particularly at the deposit/substrate interface, and 3) improving material yield. Through this program, a new strip/sheet casting process, termed spray rolling, has been developed, which is an innovative manufacturing technique to produce aluminum net-shape products. Spray rolling combines the benefits of twin-roll casting and conventional spray forming, showing a promising potential to overcome the above hurdles associated with spray forming. Spray rolling requires less energy and generates less scrap than conventional processes and, consequently, enables the development of materials with lower environmental impacts in both processing and final products. Spray Rolling was developed as a collaborative project between the University of California-Davis, the Colorado School of Mines, the Idaho National Engineering and Environmental Laboratory, and an industry team. The following objectives of this project were achieved: (1) Demonstration of the feasibility of the spray rolling process at the bench-scale level and evaluation of the materials properties of spray rolled aluminum strip alloys; and (2) Demonstration of 2X scalability of the process and documentation of technical hurdles to further scale up and initiate technology transfer to industry for eventual commercialization of the process.

  8. An overview of spray drift reduction testing of spray nozzles

    USDA-ARS?s Scientific Manuscript database

    The importance of the development and testing of drift reduction technologies (DRTs) is increasing. Common spray drift reduction technologies include spray nozzles and spray adjuvants. Following draft procedures developed for a DRT program, three spray nozzles were tested under high air speed cond...

  9. Hygroscopic behavior of NaCl-MgCl2 mixture particles as nascent sea-spray aerosol surrogates and observation of efflorescence during humidifying process

    NASA Astrophysics Data System (ADS)

    Gupta, D.; Eom, H.-J.; Cho, H.-R.; Ro, C.-U.

    2015-07-01

    NaCl and MgCl2 are the two major constituents of seawater, so NaCl-MgCl2 mixture particles can be a better representative of sea-spray aerosols (SSAs) than pure NaCl. However, there have been very few hygroscopic studies of pure MgCl2 and NaCl-MgCl2 mixture aerosol particles despite the MgCl2 moiety playing a major role in the hygroscopic behavior of nascent SSAs. Laboratory-generated pure MgCl2 and NaCl-MgCl2 mixture aerosol particles with 12 mixing ratios (0.01 ≤ mole fraction of NaCl (XNaCl) ≤ 0.9) were examined systematically by optical microscopy, in-situ Raman microspectrometry (RMS), and scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDX) elemental X-ray mapping to observe their hygroscopic behavior, derive the experimental phase diagrams, and obtain the chemical micro-structures. Dry-deposited MgCl2·6H2O particles exhibited a deliquescence relative humidity (DRH) of ∼ 33.0 % and an efflorescence RH (ERH) of 10.8-9.1 %, whereas the nebulized pure MgCl2 and MgCl2-dominant particles of XNaCl = 0.026 (eutonic) and 0.01 showed single-stage transitions at DRH of ∼ 15.9 % and ERH of 10.1-3.2 %. The characteristic OH-stretching Raman signatures indicated the crystallization of MgCl2·4H2O at low RHs, suggesting that the kinetic barrier to MgCl2·6H2O crystallization is not overcome in the timescale of the dehydration measurements. The NaCl-MgCl2 mixture particles of 0.05 ≤ XNaCl ≤ 0.9 generally showed two-stage deliquescence: first at the mutual DRH (MDRH) of ~ 15.9 %; and second with the complete dissolution of NaCl at the second DRHs depending on the mixing ratios, resulting in a phase diagram composed of three distinct phases. During dehydration, most particles of 0.05 ≤ XNaCl ≤ 0.9 exhibited two-stage efflorescence: first, by the homogeneous nucleation of NaCl; and second, at mutual ERH (MERH) of ∼ 10.4-2.9 %, by the crystallization of the MgCl2·4H2O moiety, also resulting in three distinct phases. Interestingly

  10. Hygroscopic behavior of NaCl-MgCl2 mixture particles as nascent sea-spray aerosol surrogates and observation of efflorescence during humidification

    NASA Astrophysics Data System (ADS)

    Gupta, D.; Eom, H.-J.; Cho, H.-R.; Ro, C.-U.

    2015-10-01

    As Na+, Mg2+, and Cl- are major ionic constituents of seawater, NaCl-MgCl2 mixture particles might represent sea-spray aerosols (SSAs) better than pure NaCl. However, there have been very few hygroscopic studies of pure MgCl2 and NaCl-MgCl2 mixture aerosol particles despite the MgCl2 moiety playing a major role in the hygroscopic behavior of nascent SSAs. Laboratory-generated pure MgCl2 and NaCl-MgCl2 mixture aerosol particles with 12 mixing ratios (0.01 ≤ mole fraction of NaCl (XNaCl) ≤ 0.9) were examined systematically by optical microscopy (OM), in situ Raman micro-spectrometry (RMS), and scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDX) elemental X-ray mapping to observe their hygroscopic behavior, derive the experimental phase diagrams, and obtain the chemical micro-structures. Dry-deposited MgCl2 ⋅ 6H2O particles exhibited a deliquescence relative humidity (DRH) of ~ 33.0 % and an efflorescence RH (ERH) of 10.8-9.1 %, whereas the nebulized pure MgCl2 and MgCl2-dominant particles of XNaCl = 0.026 (eutonic) and 0.01 showed single-stage transitions at DRH of ~ 15.9 % and ERH of 10.1-3.2 %. The characteristic OH-stretching Raman signatures indicated the crystallization of MgCl2 ⋅ 4H2O at low relative humidities (RHs), suggesting that the kinetic barrier to MgCl2 ⋅ 6H2O crystallization is not overcome in the timescale of the dehydration measurements. The NaCl-MgCl2 mixture particles of 0.05 ≤ XNaCl ≤ 0.9 generally showed two-stage deliquescence: first at the mutual DRH (MDRH) of ~ 15.9 %; and second with the complete dissolution of NaCl at the second DRHs depending on the mixing ratios, resulting in a phase diagram composed of three distinct phases. During dehydration, most particles of 0.05 ≤ XNaCl ≤ 0.9 exhibited two-stage efflorescence: first, by the homogeneous nucleation of NaCl; and second, at mutual ERH (MERH) of ~ 10.4-2.9 %, by the crystallization of the MgCl2 ⋅ 4H2O moiety, also resulting in three

  11. Macroscopic Description for Networks of Spiking Neurons

    NASA Astrophysics Data System (ADS)

    Montbrió, Ernest; Pazó, Diego; Roxin, Alex

    2015-04-01

    A major goal of neuroscience, statistical physics, and nonlinear dynamics is to understand how brain function arises from the collective dynamics of networks of spiking neurons. This challenge has been chiefly addressed through large-scale numerical simulations. Alternatively, researchers have formulated mean-field theories to gain insight into macroscopic states of large neuronal networks in terms of the collective firing activity of the neurons, or the firing rate. However, these theories have not succeeded in establishing an exact correspondence between the firing rate of the network and the underlying microscopic state of the spiking neurons. This has largely constrained the range of applicability of such macroscopic descriptions, particularly when trying to describe neuronal synchronization. Here, we provide the derivation of a set of exact macroscopic equations for a network of spiking neurons. Our results reveal that the spike generation mechanism of individual neurons introduces an effective coupling between two biophysically relevant macroscopic quantities, the firing rate and the mean membrane potential, which together govern the evolution of the neuronal network. The resulting equations exactly describe all possible macroscopic dynamical states of the network, including states of synchronous spiking activity. Finally, we show that the firing-rate description is related, via a conformal map, to a low-dimensional description in terms of the Kuramoto order parameter, called Ott-Antonsen theory. We anticipate that our results will be an important tool in investigating how large networks of spiking neurons self-organize in time to process and encode information in the brain.

  12. Infrared thermography-based visualization of droplet transport in liquid sprays

    NASA Astrophysics Data System (ADS)

    Akafuah, Nelson K.; Salazar, Abraham J.; Saito, Kozo

    2010-05-01

    An infrared thermography-based technique for the characterization and visualization of liquid sprays was developed. The technique was tested on two atomizers: a high-speed rotary bell atomizer and a high volume low pressure air-assisted atomizer. The technique uses an infrared thermography-based measurement in which a uniformly heated background acts as a thermal radiation source, and an infrared camera as the receiver. The infrared energy emitted by the radiation source in traveling through the spray is attenuated by the presence of the droplets inside the spray. The infrared intensity is captured by the receiver showing the attenuation in the image as a result of the presence of the spray. The captured thermal image is used to study detailed macroscopic features of the spray flow field and the evolution of the paint droplets as they are transferred from the applicator to the target surface.

  13. Thermal Arc Spray Overview

    NASA Astrophysics Data System (ADS)

    Hafiz Abd Malek, Muhamad; Hayati Saad, Nor; Kiyai Abas, Sunhaji; Mohd Shah, Noriyati

    2013-06-01

    Usage of protective coating for corrosion protection was on highly demand during the past decade; and thermal spray coating played a major part during that time. In recent years, the thermal arc spray coating becomes a popular coating. Many big players in oil and gas such as PETRONAS, EXXON MOBIL and SHELL in Malaysia tend to use the coating on steel structure as a corrosion protection. Further developments in coating processes, the devices, and raw materials have led to expansion of functional coatings and applications scope from conventional coating to specialized industries. It is widely used because of its ability to withstand high process temperature, offer advantages in efficiency, lower cost and acts as a corrosion protection. Previous research also indicated that the thermal arc spray offers better coating properties compared to other methods of spray. This paper reviews some critical area of thermal spray coating by discussing the process/parameter of thermal arc spray technology and quality control of coating. Coating performance against corrosion, wear and special characteristic of coating are also described. The field application of arc spray technology are demonstrated and reviewed.

  14. Conversion of light into macroscopic helical motion.

    PubMed

    Iamsaard, Supitchaya; Aßhoff, Sarah J; Matt, Benjamin; Kudernac, Tibor; Cornelissen, Jeroen J L M; Fletcher, Stephen P; Katsonis, Nathalie

    2014-03-01

    A key goal of nanotechnology is the development of artificial machines capable of converting molecular movement into macroscopic work. Although conversion of light into shape changes has been reported and compared to artificial muscles, real applications require work against an external load. Here, we describe the design, synthesis and operation of spring-like materials capable of converting light energy into mechanical work at the macroscopic scale. These versatile materials consist of molecular switches embedded in liquid-crystalline polymer springs. In these springs, molecular movement is converted and amplified into controlled and reversible twisting motions. The springs display complex motion, which includes winding, unwinding and helix inversion, as dictated by their initial shape. Importantly, they can produce work by moving a macroscopic object and mimicking mechanical movements, such as those used by plant tendrils to help the plant access sunlight. These functional materials have potential applications in micromechanical systems, soft robotics and artificial muscles.

  15. Nanoplasmon-enabled macroscopic thermal management

    PubMed Central

    Jonsson, Gustav Edman; Miljkovic, Vladimir; Dmitriev, Alexandre

    2014-01-01

    In numerous applications of energy harvesting via transformation of light into heat the focus recently shifted towards highly absorptive nanoplasmonic materials. It is currently established that noble metals-based absorptive plasmonic platforms deliver significant light-capturing capability and can be viewed as super-absorbers of optical radiation. Naturally, approaches to the direct experimental probing of macroscopic temperature increase resulting from these absorbers are welcomed. Here we derive a general quantitative method of characterizing heat-generating properties of optically absorptive layers via macroscopic thermal imaging. We further monitor macroscopic areas that are homogeneously heated by several degrees with nanostructures that occupy a mere 8% of the surface, leaving it essentially transparent and evidencing significant heat generation capability of nanoplasmon-enabled light capture. This has a direct bearing to a large number of applications where thermal management is crucial. PMID:24870613

  16. Conversion of light into macroscopic helical motion

    NASA Astrophysics Data System (ADS)

    Iamsaard, Supitchaya; Aßhoff, Sarah J.; Matt, Benjamin; Kudernac, Tibor; Cornelissen, Jeroen J. L. M.; Fletcher, Stephen P.; Katsonis, Nathalie

    2014-03-01

    A key goal of nanotechnology is the development of artificial machines capable of converting molecular movement into macroscopic work. Although conversion of light into shape changes has been reported and compared to artificial muscles, real applications require work against an external load. Here, we describe the design, synthesis and operation of spring-like materials capable of converting light energy into mechanical work at the macroscopic scale. These versatile materials consist of molecular switches embedded in liquid-crystalline polymer springs. In these springs, molecular movement is converted and amplified into controlled and reversible twisting motions. The springs display complex motion, which includes winding, unwinding and helix inversion, as dictated by their initial shape. Importantly, they can produce work by moving a macroscopic object and mimicking mechanical movements, such as those used by plant tendrils to help the plant access sunlight. These functional materials have potential applications in micromechanical systems, soft robotics and artificial muscles.

  17. Effects of Microstructure Variations on Macroscopic Terahertz Metafilm Properties

    DOE PAGES

    O'Hara, John F.; Smirnova, Evgenya; Azad, Abul K.; ...

    2007-01-01

    The properties of planar, single-layer metamaterials, or metafilms, are studied by varying the structural components of the split-ring resonators used to comprise the overall medium. Measurements and simulations reveal how minor design variations in split-ring resonator structures can result in significant changes in the macroscopic properties of the metafilm. A transmission-line/circuit model is also used to clarify some of the behavior and design limitations of the metafilms. Though our results are illustrated in the terahertz frequency range, the work has broader implications, particularly with respect to filtering, modulation, and switching devices.

  18. Macroscopic modeling for traffic flow on three-lane highways

    NASA Astrophysics Data System (ADS)

    Chen, Jianzhong; Fang, Yuan

    2015-04-01

    In this paper, a macroscopic traffic flow model for three-lane highways is proposed. The model is an extension of the speed gradient model by taking into account the lane changing. The new source and sink terms of lane change rate are added into the continuity equations and the speed dynamic equations to describe the lane-changing behavior. The result of the steady state analysis shows that our model can describe the lane usage inversion phenomenon. The numerical results demonstrate that the present model effectively reproduces several traffic phenomena observed in real traffic such as shock and rarefaction waves, stop-and-go waves and local clusters.

  19. Macroscopic anisotropy in AA5019A sheets

    SciTech Connect

    Choi, S.H.; Brem, J.C.; Barlat, F.; Oh, K.H.

    2000-05-11

    The macroscopic anisotropy for typical texture components in aluminum alloys and AA5019A sheet samples (H48 and O temper conditions) were investigated. In order to simultaneously consider the effects of morphological texture and crystallographic texture on macroscopic anisotropy, predictions of plastic properties were carried out using a full-constraints Taylor model and a visco-plastic self-consistent (VPSC) polycrystal model. The yield stress and r-value (width-to-thickness plastic strain ratio in uniaxial tension) anisotropy predicted using the VPSC model were in good agreement with experimental data.

  20. Quantum communication with macroscopically bright nonclassical states.

    PubMed

    Usenko, Vladyslav C; Ruppert, Laszlo; Filip, Radim

    2015-11-30

    We analyze homodyne detection of macroscopically bright multimode nonclassical states of light and propose their application in quantum communication. We observe that the homodyne detection is sensitive to a mode-matching of the bright light to the highly intense local oscillator. Unmatched bright modes of light result in additional noise which technically limits detection of Gaussian entanglement at macroscopic level. When the mode-matching is sufficient, we show that multimode quantum key distribution with bright beams is feasible. It finally merges the quantum communication with classical optical technology of visible beams of light.

  1. Macroscopic Quantum Superposition in Cavity Optomechanics

    NASA Astrophysics Data System (ADS)

    Liao, Jie-Qiao; Tian, Lin

    2016-04-01

    Quantum superposition in mechanical systems is not only key evidence for macroscopic quantum coherence, but can also be utilized in modern quantum technology. Here we propose an efficient approach for creating macroscopically distinct mechanical superposition states in a two-mode optomechanical system. Photon hopping between the two cavity modes is modulated sinusoidally. The modulated photon tunneling enables an ultrastrong radiation-pressure force acting on the mechanical resonator, and hence significantly increases the mechanical displacement induced by a single photon. We study systematically the generation of the Yurke-Stoler-like states in the presence of system dissipations. We also discuss the experimental implementation of this scheme.

  2. Dependence of scale thickness on the breaking behavior of the initial oxide on plasma spray bond coat surface during vacuum pre-treatment

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

    The thermally grown oxide (TGO) on the thermal spray bond coat surface was one of the most important factors which would influence the lifetime of thermal barrier coatings (TBCs). Pre-diffusion treatment (high temperature vacuum treatment) plays an important role in the growth of the TGO. Results show that the initial thin oxide scale, formed during deposition process, on the as-sprayed bond coating surface has broken and shrunk to discontinuous oxide particles through the elements diffusion during the pre-diffusion. Two kinds of bond coats with different initial oxide scale thicknesses were subjected to the same pre-diffusion. The two pre-diffused bond coats show different results of the average distance between the individual oxide particles. In this study, a three dimensional model with thermal grooving theory was developed to explore the essential condition for the scale breaking and explain the differences of these results. This research can provide reference for the preparation optimization and pre-treatment optimization of bond coat towards high performance TBCs.

  3. Influence of Al2O3 Particle Size on Microstructure, Mechanical Properties and Abrasive Wear Behavior of Flame-Sprayed and Remelted NiCrBSi Coatings

    NASA Astrophysics Data System (ADS)

    Habib, K. A.; Cano, D. L.; Caudet, C. T.; Damra, M. S.; Cervera, I.; Bellés, J.; Ortells, P.

    2017-04-01

    The influence of micrometric alumina (low surface area-to-volume ratio) and nanometric alumina (high surface area-to-volume ratio) on microstructure, hardness and abrasive wear of a NiCrBSi hardfacing alloy coating applied to an AISI 304 substrate using flame spraying (FS) combined with surface flame melting (SFM) is studied. Remelting after spraying improved the mechanical and tribological properties of the coatings. Microstructural characterization using XRD, SEM and EDS indicated that alumina additions produced similar phases (NiSi, Ni3B, CrC and Ni31Si12) regardless of the alumina size, but the phases differed in morphology, size distribution and relative proportions from one coating to another. The addition of 12 wt.% nanometric Al2O3 increased the phases concentration more than five- to sixfold and reduced the hard phases size about four-to threefold compared with NiCrBSi + 12 wt.% micrometric Al2O3. Nanoalumina led to reduced mass loss during abrasive wear compared to micrometric alumina and greater improvement in hardness.

  4. Effect of different combinations of maltodextrin, gum arabic and whey protein concentrate on the encapsulation behavior and oxidative stability of spray dried drumstick (Moringa oleifera) oil.

    PubMed

    Premi, Monica; Sharma, H K

    2017-07-27

    The objective of the present study was to investigate the effect of different combinations of carrier agents (Maltodextrin, gum arabic and whey protein concentrate) on the emulsion properties, encapsulation efficiency and oxidative stability of encapsulated drumstick oil powder (EDOP), produced by spray drying to increase its usage as an active ingredient. Feed emulsion characteristics were studied in terms of emulsion stability, droplet size, viscosity and surface charge. Obtained spray dried EDOP was characterized for physical and flow properties, microstructure and oxidative stability. EDOP obtained from the MD:GA emulsion showed higher encapsulation efficiency than MD:WPC. Higher encapsulation efficiency along with medium flow properties and better oxidative stability was observed with microcapsules obtained by MD:GA carrier agent. Microstructure of EDOP with MD:GA showed no cracks, smother appearance with continuous wall. EDOP with MD:GA had better stability and were stable at 45°C, which confirms the protective effect of this carrier agent in encapsulating the drumstick oil. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Influence of Al2O3 Particle Size on Microstructure, Mechanical Properties and Abrasive Wear Behavior of Flame-Sprayed and Remelted NiCrBSi Coatings

    NASA Astrophysics Data System (ADS)

    Habib, K. A.; Cano, D. L.; Caudet, C. T.; Damra, M. S.; Cervera, I.; Bellés, J.; Ortells, P.

    2017-03-01

    The influence of micrometric alumina (low surface area-to-volume ratio) and nanometric alumina (high surface area-to-volume ratio) on microstructure, hardness and abrasive wear of a NiCrBSi hardfacing alloy coating applied to an AISI 304 substrate using flame spraying (FS) combined with surface flame melting (SFM) is studied. Remelting after spraying improved the mechanical and tribological properties of the coatings. Microstructural characterization using XRD, SEM and EDS indicated that alumina additions produced similar phases (NiSi, Ni3B, CrC and Ni31Si12) regardless of the alumina size, but the phases differed in morphology, size distribution and relative proportions from one coating to another. The addition of 12 wt.% nanometric Al2O3 increased the phases concentration more than five- to sixfold and reduced the hard phases size about four-to threefold compared with NiCrBSi + 12 wt.% micrometric Al2O3. Nanoalumina led to reduced mass loss during abrasive wear compared to micrometric alumina and greater improvement in hardness.

  6. Nasal corticosteroid sprays

    MedlinePlus

    ... best for decreasing symptoms during that season. Several brands of nasal corticosteroid sprays are available. They all ... urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows ...

  7. Budesonide Nasal Spray

    MedlinePlus

    ... by an allergy to pollen, mold, dust, or pets). Budesonide nasal spray should not be used to ... disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, ...

  8. Fluticasone Nasal Spray

    MedlinePlus

    ... the pump until you see a fine spray. Blow your nose until your nostrils are clear. Hold ... chills, cough, and other signs of infection whistling sound from the nose hives rash itching swelling of ...

  9. Supersonic-Spray Cleaner

    NASA Technical Reports Server (NTRS)

    Caimi, Raoul E. B.; Lin, Feng-Nan; Thaxton, Eric A.

    1995-01-01

    Spraying system for cleaning mechanical components uses less liquid and operates at pressures significantly lower. Liquid currently used is water. Designed to replace chlorofluorocarbon (CFC) solvent-based cleaning and cleanliness verification methods. Consists of spray head containing supersonic converging/diverging nozzles, source of gas at regulated pressure, pressurized liquid tank, and various hoses, fittings, valves, and gauges. Parameters of nozzles set so any of large variety of liquids and gases combined in desired ratio and rate of flow. Size and number of nozzles varied so system built in configurations ranging from small hand-held spray heads to large multinozzle cleaners. Also used to verify part adequately cleaned. Runoff liquid from spray directed at part collected. Liquid analyzed for presence of contaminants, and part recleaned if necessary.

  10. Beclomethasone Nasal Spray

    MedlinePlus

    ... the lining of the nose) after nasal polyp removal surgery. Beclomethasone nasal spray should not be used ... room temperature and away from excess heat and moisture (not in the bathroom).Unneeded medications should be ...

  11. Ciclesonide Nasal Spray

    MedlinePlus

    ... runny or itchy nose. Ciclesonide is in a class of medications called corticosteroids. It works by preventing ... hold the bottle firmly with your forefinger and middle finger on either side of the spray tip ...

  12. Flunisolide Nasal Spray

    MedlinePlus

    ... by the common cold. It is in a class of medications called corticosteroids. It works by blocking ... spray with the applicator between your forefinger and middle finger and the bottom of the bottle resting ...

  13. Nicotine Nasal Spray

    MedlinePlus

    ... the bottle in front of a tissue or paper towel. Pump the spray bottle six to eight times ... up the spill immediately with a cloth or paper towel. Avoid touching the liquid. Throw away the used ...

  14. Spray forming of superplastic aluminum sheet

    SciTech Connect

    Lavender, C.A.; Smith, M.T.; McHugh, K.M.; Key, J.F.

    1995-12-31

    Ingot metallurgy (I/M) processing methods for superplastic aluminum sheet require substantial hot, warm and final cold rolling reduction steps to produce the desired fine grain size and thermally-stable microstructure necessary for superplastic forming (SPF). The rapid solidification rates associated with spray forming offer the potential for economic processing of near net-thickness SPF sheet having alloy compositions that are not possible with conventional ingot metallurgy. To evaluate the application of spray forming for SPF aluminum sheet, a modified 5083 alloy was supplied to Idaho National Engineering Laboratory for processing using laboratory spray-forming equipment. Spray-formed sheet specimens were then supplied to the Battelle Pacific Northwest Laboratory for characterization and comparison with conventional I/M-based SPF sheet. Results show that the spray formed material, when processed using appropriate homogenization and cold reduction steps (3:1 total reduction), has an equiaxed grain size of 2--4 {micro}m near the deposition substrate. However, microstructural examination indicates that grain size increases as a function of the distance from the deposition substrate. Tensile tests were conducted at a temperature of 550 C and constant strain rates over a range of 5 {times} 10{sup {minus}4} to 5 {times} 10{sup {minus}3} s{sup {minus}1} to evaluate the superplastic behavior of the spray-formed samples. Results show that the spray-formed material having a 3:1 cold rolling reduction has superplastic elongation equivalent to I/M materials processed with a 60:1 reduction.

  15. Sensors in Spray Processes

    NASA Astrophysics Data System (ADS)

    Fauchais, P.; Vardelle, M.

    2010-06-01

    This paper presents what is our actual knowledge about sensors, used in the harsh environment of spray booths, to improve the reproducibility and reliability of coatings sprayed with hot or cold gases. First are described, with their limitations and precisions, the different sensors following the in-flight hot particle parameters (trajectories, temperatures, velocities, sizes, and shapes). A few comments are also made about techniques, still under developments in laboratories, to improve our understanding of coating formation such as plasma jet temperature measurements in non-symmetrical conditions, hot gases heat flux, particles flattening and splats formation, particles evaporation. Then are described the illumination techniques by laser flash of either cold particles (those injected in hot gases, or in cold spray gun) or liquid injected into hot gases (suspensions or solutions). The possibilities they open to determine the flux and velocities of cold particles or visualize liquid penetration in the core of hot gases are discussed. Afterwards are presented sensors to follow, when spraying hot particles, substrate and coating temperature evolution, and the stress development within coatings during the spray process as well as the coating thickness. The different uses of these sensors are then described with successively: (i) Measurements limited to particle trajectories, velocities, temperatures, and sizes in different spray conditions: plasma (including transient conditions due to arc root fluctuations in d.c. plasma jets), HVOF, wire arc, cold spray. Afterwards are discussed how such sensor data can be used to achieve a better understanding of the different spray processes, compare experiments to calculations and improve the reproducibility and reliability of the spray conditions. (ii) Coatings monitoring through in-flight measurements coupled with those devoted to coatings formation. This is achieved by either maintaining at their set point both in-flight and

  16. Spray applicator for spraying coatings and other fluids in space

    NASA Technical Reports Server (NTRS)

    Kuminecz, J. F.; Lausten, M. F. (Inventor)

    1985-01-01

    A self contained spray application is developed for one handed operation in a zero gravity vacuum environment by a free flying astronaut not attached to any spacecraft. This spray applicator eliminates contamination of the operator by back spray. This applicator includes a rigid accumulator containment of a fluid within a flexible bladder the fluid being urged out of the accumulator under pressure through a spray gun. The spray gun includes a spring loaded lockable trigger which controls a valve. When in an open position, the fluid passes through the valve into the ambient environment in the form of a spray. A spray shield is provided which directs the flow of the spray from the applicator by trapping errant particles of spray yet allowing the passage of escaping gases through its material.

  17. Collective Phenomena in Macroscopic Systems

    NASA Astrophysics Data System (ADS)

    Bertin, G.; Pozzoli, R.; Romé, M.; Sreenivasan, K. R.

    2007-08-01

    for high and low B plasmas / E. Tassi, P. J. Morrison and D. Grasso -- Non locality of collective effects related to dynamical friction in elliptical galaxies / S.E. Arena and G. Bertin -- Evolution of a satellite dragged in by dynamical friction towards the center of a galaxy / S.E. Arena, G. Bertin and T. Liseykina -- Investigation of free decaying turbulence in a trapped pure electron plasma / G. Bettega ... [et al.] -- Structures of charge sheaths and transition layers in ion sources / M. Cavenago -- Generation of plasma perturbations under collisionless interaction of super-Alfvenic flows / G. Dudnikova, T. Liseykina and K. Vshivkov -- Program package for 3D Pic model of plasma fiber / P. Kulhanek and D. Bren -- A Stochastic approach to generalized quantum dynamics with collective long-range forces / A. Lavagno -- Filling of Electrostatic Plasma Lens for Ion-Beam-Focusing by electrons against direction of electric field due to non-linear vortex behavior / V. Maslov -- Thermal barrier formation for plasma electrons and ions in kind of connected solitary dip and hump of electric potential near ECR points in cylindrical trap / V. Maslov ... [et al.] -- Excitation of solitary wake-field by relativistic electron bunch and laser pulse / V. Maslov, A. Egorov and I. Onishchenko -- Enhancement of ion beam charge states by electron vortices in a plasma optical device / V. Maslov, A. Goncharov and I. Brown -- Wake-field mechanism of ion quasi-crystal formation in nonequilibrium dusty plasmas of technological devices / V. Maslov ... [et al.] -- Spiral perturbation in separator for extraction of heavy drops from plasma flow / V. Maslov ... [et al.] -- Fractional relaxation equation from AC universality in disordered solids / A. V. Milovanov, K. Rypdal and J. J. Rasmussen -- Vortices in two-dimensional rotating bose-Einstein condensates / T. Rindler-Daller -- Studying instability of 3D collisionless systems on Stochastic trajectories / V. N. Snytnikov and E. A. Kuksheva

  18. Directed spray mast

    DOEpatents

    Nance, Thomas A.; Siddall, Alvin A.; Cheng, William Y.; Counts, Kevin T.

    2005-05-10

    Disclosed is an elongated, tubular, compact high pressure sprayer apparatus for insertion into an access port of vessels having contaminated interior areas that require cleaning by high pressure water spray. The invention includes a spray nozzle and a camera adjacent thereto with means for rotating and raising and lowering the nozzle so that areas identified through the camera may be cleaned with a minimum production of waste water to be removed.

  19. Metal atomization spray nozzle

    DOEpatents

    Huxford, Theodore J.

    1993-01-01

    A spray nozzle for a magnetohydrodynamic atomization apparatus has a feed passage for molten metal and a pair of spray electrodes mounted in the feed passage. The electrodes, diverging surfaces which define a nozzle throat and diverge at an acute angle from the throat. Current passes through molten metal when fed through the throat which creates the Lorentz force necessary to provide atomization of the molten metal.

  20. Portable Spray Booth

    NASA Technical Reports Server (NTRS)

    Hansen, Timothy D.; Bardwell, Micheal J.

    1996-01-01

    Portable spray booth provides for controlled application of coating materials with high solvent contents. Includes contoured shroud and carbon filter bed limiting concentration of fumes in vicinity. Designed to substitute spraying for brush application of solvent-based adhesive prior to installing rubber waterproof seals over joints between segments of solid-fuel rocket motor. With minor adjustments and modifications, used to apply other solvent-based adhesives, paints, and like.

  1. Portable Spray Booth

    NASA Technical Reports Server (NTRS)

    Hansen, Timothy D.; Bardwell, Micheal J.

    1996-01-01

    Portable spray booth provides for controlled application of coating materials with high solvent contents. Includes contoured shroud and carbon filter bed limiting concentration of fumes in vicinity. Designed to substitute spraying for brush application of solvent-based adhesive prior to installing rubber waterproof seals over joints between segments of solid-fuel rocket motor. With minor adjustments and modifications, used to apply other solvent-based adhesives, paints, and like.

  2. Metal atomization spray nozzle

    DOEpatents

    Huxford, T.J.

    1993-11-16

    A spray nozzle for a magnetohydrodynamic atomization apparatus has a feed passage for molten metal and a pair of spray electrodes mounted in the feed passage. The electrodes, diverging surfaces which define a nozzle throat and diverge at an acute angle from the throat. Current passes through molten metal when fed through the throat which creates the Lorentz force necessary to provide atomization of the molten metal. 6 figures.

  3. Cavitation-erosion of thermal sprayed hardfacing coatings

    SciTech Connect

    Guo, X.

    1988-01-01

    An investigation has been carried out on the cavitation-erosion behavior of thermal sprayed WC-Co and Tribaloy (T-400) coatings. The thermal spray processes used were air and vacuum plasma spraying and hypersonic flame or Jet Kote spraying. The principal goals of this work were to investigate the influence of the three types of spray processes on the coating microstructure and cavitation-erosion behavior. It was found that spray atmosphere is a critical parameter in thermal spraying of WC-Co coatings. For the case of WC-Co materials, decomposition and dissolution of the carbide occur during air plasma and Jet Kote spraying processes, while no apparent decomposition and dissolution of the carbide were observed for vacuum plasma spraying. Tribaloy coatings produced by these three spray processes showed metastable mixtures of amorphous and microcrystalline phases, as well as supersaturated solid solution due to rapid solidification. Upon the heat treatment (at 1175 C for 5 minutes), these metastable phases were transformed to more stable phases. Laser treatment gave a dense coating surface structure, pore-free and crack-free surfaces, and resulted in significantly improved cavitation-erosion resistance. The main factors leading to enhanced cavitation-erosion resistance of the Tribaloy coatings are: (i) high coating density; (ii) high proportion of Laves phase; (iii) stress-induced phase transformation; and (iv) a low level of microstructural defects. The corrosive aspects of cavitation-erosion and electrochemical measurements showed that porosity was the predominant factor influencing cavitation-corrosion and corrosion behaviors.

  4. Macroscopic Quantum Cotunneling of Phase Slips

    NASA Astrophysics Data System (ADS)

    Belkin, Andrey; Belkin, Maxim; Vakaryuk, Victor; Khlebnikov, Sergei; Bezryadin, Alexey

    2014-03-01

    Quantum phenomena that do not have analogues in the classical world include quantum superposition and tunneling. Despite significant efforts invested into demonstration of quantum effects at the macroscopic level, the main principles that govern the transition from classical to quantum are not well understood. Here we report a study of macroscopic quantum tunneling of phase slips that involve both superconducting and normal degrees of freedom in a superconducting nanowire loop. We discover that in addition to single phase slips that unwind the phase difference along the loop by 2 π, there are transitions that change the phase by 4 π. Experimentally we identify the regime in which, surprisingly, 4 π phase slips are more likely than 2 π ones. We interpret our observations in terms of macroscopic cotunneling effect defined as an exact synchronization of two macroscopic phase slip events. The work was supported by grant the DOE Award No. DE-FG0207ER46453, and the NSF No. DMR10-05645

  5. Berkeley Experiments on Superfluid Macroscopic Quantum Effects

    SciTech Connect

    Packard, Richard

    2006-09-07

    This paper provides a brief history of the evolution of the Berkeley experiments on macroscopic quantum effects in superfluid helium. The narrative follows the evolution of the experiments proceeding from the detection of single vortex lines to vortex photography to quantized circulation in 3He to Josephson effects and superfluid gyroscopes in both 4He and 3He.

  6. Macroscopic Modeling of Polymer-Electrolyte Membranes

    SciTech Connect

    Weber, A.Z.; Newman, J.

    2007-04-01

    In this chapter, the various approaches for the macroscopic modeling of transport phenomena in polymer-electrolyte membranes are discussed. This includes general background and modeling methodologies, as well as exploration of the governing equations and some membrane-related topic of interest.

  7. [Macroscopic hematuria in an adolescent in Chad].

    PubMed

    Ballivet de Régloix, S; Maurin, O; Douniama Ondaï, C

    2012-01-01

    We report the case of a 16-year-old Chadian boy referred for chronic macroscopic hematuria and dysuria, diagnosed as urinary schistosomiasis, contracted while bathing in contaminated fresh water. The diagnostic approach and treatment in light of the limited resources available in Africa are described in detail.

  8. Lozenge Tilings, Glauber Dynamics and Macroscopic Shape

    NASA Astrophysics Data System (ADS)

    Laslier, Benoît; Toninelli, Fabio Lucio

    2015-09-01

    We study the Glauber dynamics on the set of tilings of a finite domain of the plane with lozenges of side 1/ L. Under the invariant measure of the process (the uniform measure over all tilings), it is well known (Cohn et al. J Am Math Soc 14:297-346, 2001) that the random height function associated to the tiling converges in probability, in the scaling limit , to a non-trivial macroscopic shape minimizing a certain surface tension functional. According to the boundary conditions, the macroscopic shape can be either analytic or contain "frozen regions" (Arctic Circle phenomenon Cohn et al. N Y J Math 4:137-165, 1998; Jockusch et al. Random domino tilings and the arctic circle theorem, arXiv:math/9801068, 1998). It is widely conjectured, on the basis of theoretical considerations (Henley J Statist Phys 89:483-507, 1997; Spohn J Stat Phys 71:1081-1132, 1993), partial mathematical results (Caputo et al. Commun Math Phys 311:157-189, 2012; Wilson Ann Appl Probab 14:274-325, 2004) and numerical simulations for similar models (Destainville Phys Rev Lett 88:030601, 2002; cf. also the bibliography in Henley (J Statist Phys 89:483-507, 1997) and Wilson (Ann Appl Probab 14:274-325, 2004), that the Glauber dynamics approaches the equilibrium macroscopic shape in a time of order L 2+ o(1). In this work we prove this conjecture, under the assumption that the macroscopic equilibrium shape contains no "frozen region".

  9. Plastic flow of plasma sprayed ceramics

    NASA Technical Reports Server (NTRS)

    Padovan, J.; Chung, B. T. F.; Braun, M. J.; Mcdonald, G.; Hendricks, R. C.; Mullen, R. L.

    1984-01-01

    The plastic flow of plasma-sprayed ZrO2-8Y2O3 ceramic has been measured at temperatures up to 1250 C and compared to the plastic flow of pressed and sintered ZrO2-8Y2O3. Plasma spraying of binary oxide ceramics is found to result in a metastable state which is inelastic at high temperature but can also be stabilized or devitrified through heat treating so as to decrease plastic properties. The mechanical properties of the as-plasma sprayed and devitrified ceramic sheet material was measured. An improved algorithm that incorporates the inherently nonlinear thermomechanical field equations was used to determine the influence of inelastic material behavior on the thermomechanical response of ceramic coated seal components. Significant creep was found during the thermal shock and steady heating periods with insufficient time during thermal quench to reverse the process, thereby inducing significant residual stresses into the components.

  10. Plasma-sprayed coatings

    SciTech Connect

    Herman, H.

    1988-09-01

    Plasma spraying is one way to apply protective coatings. The hot, high-speed flame of a plasma gun can melt a powder of almost any ceramic or metal and spray it to form a coating for protection against corrosion, wear or high temperature. The technique carries much less risk of degrading the coating and substrate than many other high-temperature processes do, because the gas in the plasma flame is chemically inert and the target can be kept fairly cool. And yet a plasma gun can be only a little more cumbersome than a paint sprayer. Investigators are applying this technique to new materials. The General Electric Company is using vacuum plasma spraying to make freestanding components: intricate aircraft engine parts formed by plasma-spraying a superalloy on a removable substrate. Other workers spray ceramic particles or fibers and metal powder simulatious wrong, stiff composite materials: the ceramic particles dispersed in a matrix of metal. The author and colleagues at the U.S. Naval Research Laboratory have fabricated a thick film of high-temperature superconductor by plasma-spraying the compound in the form of a powder. 7 figs.

  11. [Study on totai flavonoids of Epimedium assisted with soybean polysaccharide spray-drying powder].

    PubMed

    Yan, Hong-mei; Jia, Xiao-bin; Zhang, Zhen-hai; Sun, E; Deng, Jia-hui

    2015-08-01

    In order to evaluate the characteristics of the spray drying of total flavonoids of Epimedium extracts assisted with soybean polysaccharide, a certain percentage of soybean polysaccharide or polyvidone were added to the total flavonoids of Epimedium extract to conduct the spray drying. The effect of soybean polysaccharides against the wall sticking effect of the spray drying was detected, as well as the powder property of total flavonoids of Epimedium spray drying powder and the dissolution in vitro behavior of the effective component. Compared with the total flavonoids of Epimedium spray drying powder, soybean polysaccharide revealed a significant anti-wall sticking effect. The spray drying power which had no notable change in the grain size made a increase in the fluidity, improvement in the moisture absorption and remarkable rise in the dissolution in vitro behavior. It was worth further studying the application of soybean polysaccharide in spray drying power of traditional Chinese medicine.

  12. Measurements in liquid fuel sprays

    NASA Technical Reports Server (NTRS)

    Chigier, N.

    1984-01-01

    Techniques for studying the events directly preceding combustion in the liquid fuel sprays are being used to provide information as a function of space and time on droplet size, shape, number density, position, angle of flight and velocity. Spray chambers were designed and constructed for: (1) air-assist liquid fuel research sprays; (2) high pressure and temperature chamber for pulsed diesel fuel sprays; and (3) coal-water slurry sprays. Recent results utilizing photography, cinematography, and calibration of the Malvern particle sizer are reported. Systems for simultaneous measurement of velocity and particle size distributions using laser Doppler anemometry interferometry and the application of holography in liquid fuel sprays are being calibrated.

  13. Imparting large macroscopic changes with small changes in polypeptide composition

    NASA Astrophysics Data System (ADS)

    Sing, Michelle; McKinley, Gareth; Olsen, Bradley

    Block copolymers composed of polypeptides provide an excellent platform for exploring the underlying physics surrounding macroscopic associative network behavior. Previous work in our group has elucidated a difference in the mechanical properties of two nearly identical elastin-like polypeptide (ELP) endblocks. In poly(ELP)s, this substitution is known to result in tighter beta turns. These beta turns exhibit slower responses to changes in temperature within the material. Under shear, the modulus for the alanine-containing ELP triblock is almost three times higher than the glycine-containing ELP. Additionally, preliminary tensile tests show higher stress and strain at break for the alanine ELP triblock. We are able to explain the reasons for this behavior using a variety of spectroscopic and analytical techniques. Small angle neutron and x-ray scattering indicate differences in ordering between the alanine and glycine containing ELP materials both in shear and in stagnant flow.

  14. Thermal spray processing

    NASA Technical Reports Server (NTRS)

    Herman, H.; Berndt, C. C.

    1995-01-01

    Thermal spray processing has been used for a number of years to cost-effecticely apply TBC's for a wide range of heat engine applications. In particular, bond coats are applied by plasma spray and HVOF techniques and partially-stabilized zirconia top coats are applied by plasma spray methods. Thermal spray involves melting and rapid transport of the molten particles to the substrate, where high-rate solidification and coating build-up occur. It is the very nature of this melt processing that leads to the unique layered microstructure, as well as the apparent imperfections, so readily identified with thermal spray. Modeling the process, process-induced residual stresses, and thermal conductivity will be discussed in light of a new understanding of porosity and its anisotropy. Microcracking can be understood using new approaches, allowing a fuller view of the processing-performance connection. Detailed electron microscopic, novel neutron diffraction and fracture analysis of the deposits can lead to a better understanding of how overall microstructure can be controlled to influence critical properties of the deposited TBC system.

  15. Granulometric characterization of airborne particulate release during spray application of nanoparticle-doped coatings

    NASA Astrophysics Data System (ADS)

    Göhler, Daniel; Stintz, Michael

    2014-08-01

    Airborne particle release during the spray application of coatings was analyzed in the nanometre and micrometre size range. In order to represent realistic conditions of domestic and handcraft use, the spray application was performed using two types of commercial propellant spray cans and a manual gravity spray gun. Four different types of coatings doped with three kinds of metal-oxide tracer nanoparticle additives (TNPA) were analyzed. Depending on the used coating and the kind of spray unit, particulate release numbers between 5 × 108 and 3 × 1010 particles per gram ejection mass were determined in the dried spray aerosols. The nanoparticulate fraction amounted values between 10 and 60 no%. The comparison between nanoparticle-doped coatings with non-doped ones showed no TNPA-attributed differences in both the macroscopic spray process characteristics and the particle release numbers. SEM, TEM and EDX-analyzes showed that the spray aerosols were composed of particles made up solely from matrix material and sheathed pigments, fillers and TNPAs. Isolated ZnO- or Fe2O3-TNPAs could not be observed.

  16. Granulometric characterization of airborne particulate release during spray application of nanoparticle-doped coatings.

    PubMed

    Göhler, Daniel; Stintz, Michael

    2014-01-01

    Airborne particle release during the spray application of coatings was analyzed in the nanometre and micrometre size range. In order to represent realistic conditions of domestic and handcraft use, the spray application was performed using two types of commercial propellant spray cans and a manual gravity spray gun. Four different types of coatings doped with three kinds of metal-oxide tracer nanoparticle additives (TNPA) were analyzed. Depending on the used coating and the kind of spray unit, particulate release numbers between 5 × 10(8) and 3 × 10(10) particles per gram ejection mass were determined in the dried spray aerosols. The nanoparticulate fraction amounted values between 10 and 60 no%. The comparison between nanoparticle-doped coatings with non-doped ones showed no TNPA-attributed differences in both the macroscopic spray process characteristics and the particle release numbers. SEM, TEM and EDX-analyzes showed that the spray aerosols were composed of particles made up solely from matrix material and sheathed pigments, fillers and TNPAs. Isolated ZnO- or Fe2O3-TNPAs could not be observed.

  17. Understanding the Pulsar High Energy Emission: Macroscopic and Kinetic Models

    NASA Astrophysics Data System (ADS)

    Kalapotharakos, Constantinos; Brambilla, Gabriele; Timokhin, Andrey; Kust Harding, Alice; Kazanas, Demos

    2017-08-01

    Pulsars are extraordinary objects powered by the rotation of magnetic fields of order 10^8, 10^12G anchored onto neutron stars and rotating with periods 10^(-3)-10s. These fields mediate the conversion of their rotational energy into MHD winds and at the same time accelerate particles to energies sufficiently high to produce GeV photons. Fermi, since its launch in 2008, has established several trends among the observed gamma-ray pulsar properties playing a catalytic role in the current modeling of the high energy emission in pulsar magnetospheres. We judiciously use the guidance provided by the Fermi data to yield meaningful constraints on the macroscopic parameters of our global dissipative pulsar magnetosphere models. Our FIDO (Force-Free Inside, Dissipative Outside) models indicate that the dissipative regions lie outside the light cylinder near the equatorial current sheet. Our models reproduce the light-curve phenomenology while a detailed comparison of the model spectral properties with those observed by Fermi reveals the dependence of the macroscopic conductivity parameter on the spin-down rate providing a unique insight into the understanding of the physical mechanisms behind the high-energy emission in pulsar magnetospheres. Finally, we further exploit these important results by building self-consistent 3D global kinetic particle-in-cell (PIC) models which, eventually, provide the dependence of the macroscopic parameter behavior (e.g. conductivity) on the microphysical properties (e.g. particle multiplicities, particle injection rates). Our PIC models provide field structures and particle distributions that are not only consistent with each other but also able to reproduce a broad range of the observed gamma-ray phenomenology (light curves and spectral properties) of both young and millisecond pulsars.

  18. Macroscopic entrainment of periodically forced oscillatory ensembles.

    PubMed

    Popovych, Oleksandr V; Tass, Peter A

    2011-03-01

    Large-amplitude oscillations of macroscopic neuronal signals, such as local field potentials and electroencephalography or magnetoencephalography signals, are commonly considered as being generated by a population of mutually synchronized neurons. In a computational study in generic networks of phase oscillators and bursting neurons, however, we show that this common belief may be wrong if the neuronal population receives an external rhythmic input. The latter may stem from another neuronal population or an external, e.g., sensory or electrical, source. In that case the population field potential may be entrained by the rhythmic input, whereas the individual neurons are phase desynchronized both mutually and with their field potential. Intriguingly, the corresponding large-amplitude oscillations of the population mean field are generated by pairwise desynchronized neurons oscillating at frequencies shifted far away from the frequency of the macroscopic field potential.

  19. Macroscopic transport by synthetic molecular machines

    NASA Astrophysics Data System (ADS)

    Berná, José; Leigh, David A.; Lubomska, Monika; Mendoza, Sandra M.; Pérez, Emilio M.; Rudolf, Petra; Teobaldi, Gilberto; Zerbetto, Francesco

    2005-09-01

    Nature uses molecular motors and machines in virtually every significant biological process, but demonstrating that simpler artificial structures operating through the same gross mechanisms can be interfaced with-and perform physical tasks in-the macroscopic world represents a significant hurdle for molecular nanotechnology. Here we describe a wholly synthetic molecular system that converts an external energy source (light) into biased brownian motion to transport a macroscopic cargo and do measurable work. The millimetre-scale directional transport of a liquid on a surface is achieved by using the biased brownian motion of stimuli-responsive rotaxanes (`molecular shuttles') to expose or conceal fluoroalkane residues and thereby modify surface tension. The collective operation of a monolayer of the molecular shuttles is sufficient to power the movement of a microlitre droplet of diiodomethane up a twelve-degree incline.

  20. Macroscopic Quantum Superposition in Cavity Optomechanics

    NASA Astrophysics Data System (ADS)

    Liao, Jie-Qiao; Tian, Lin

    Quantum superposition in mechanical systems is not only a key evidence of macroscopic quantum coherence, but can also be utilized in modern quantum technology. Here we propose an efficient approach for creating macroscopically distinct mechanical superposition states in a two-mode optomechanical system. Photon hopping between the two cavity-modes is modulated sinusoidally. The modulated photon tunneling enables an ultrastrong radiation-pressure force acting on the mechanical resonator, and hence significantly increases the mechanical displacement induced by a single photon. We present systematic studies on the generation of the Yurke-Stoler-like states in the presence of system dissipations. The state generation method is general and it can be implemented with either optomechanical or electromechanical systems. The authors are supported by the National Science Foundation under Award No. NSF-DMR-0956064 and the DARPA ORCHID program through AFOSR.

  1. Adsorption modeling for macroscopic contaminant dispersal analysis

    SciTech Connect

    Axley, J.W.

    1990-05-01

    Two families of macroscopic adsorption models are formulated, based on fundamental principles of adsorption science and technology, that may be used for macroscopic (such as whole-building) contaminant dispersal analysis. The first family of adsorption models - the Equilibrium Adsorption (EA) Models - are based upon the simple requirement of equilibrium between adsorbent and room air. The second family - the Boundary Layer Diffusion Controlled Adsorption (BLDC) Models - add to the equilibrium requirement a boundary layer model for diffusion of the adsorbate from the room air to the adsorbent surface. Two members of each of these families are explicitly discussed, one based on the linear adsorption isotherm model and the other on the Langmuir model. The linear variants of each family are applied to model the adsorption dynamics of formaldehyde in gypsum wall board and compared to measured data.

  2. Macroscopic invisibility cloaking of visible light

    PubMed Central

    Chen, Xianzhong; Luo, Yu; Zhang, Jingjing; Jiang, Kyle; Pendry, John B.; Zhang, Shuang

    2011-01-01

    Invisibility cloaks, which used to be confined to the realm of fiction, have now been turned into a scientific reality thanks to the enabling theoretical tools of transformation optics and conformal mapping. Inspired by those theoretical works, the experimental realization of electromagnetic invisibility cloaks has been reported at various electromagnetic frequencies. All the invisibility cloaks demonstrated thus far, however, have relied on nano- or micro-fabricated artificial composite materials with spatially varying electromagnetic properties, which limit the size of the cloaked region to a few wavelengths. Here, we report the first realization of a macroscopic volumetric invisibility cloak constructed from natural birefringent crystals. The cloak operates at visible frequencies and is capable of hiding, for a specific light polarization, three-dimensional objects of the scale of centimetres and millimetres. Our work opens avenues for future applications with macroscopic cloaking devices. PMID:21285954

  3. Macroscopic invisibility cloak for visible light.

    PubMed

    Zhang, Baile; Luo, Yuan; Liu, Xiaogang; Barbastathis, George

    2011-01-21

    Invisibility cloaks, a subject that usually occurs in science fiction and myths, have attracted wide interest recently because of their possible realization. The biggest challenge to true invisibility is known to be the cloaking of a macroscopic object in the broad range of wavelengths visible to the human eye. Here we experimentally solve this problem by incorporating the principle of transformation optics into a conventional optical lens fabrication with low-cost materials and simple manufacturing techniques. A transparent cloak made of two pieces of calcite is created. This cloak is able to conceal a macroscopic object with a maximum height of 2 mm, larger than 3500 free-space-wavelength, inside a transparent liquid environment. Its working bandwidth encompassing red, green, and blue light is also demonstrated.

  4. Macroscopic invisibility cloaking of visible light.

    PubMed

    Chen, Xianzhong; Luo, Yu; Zhang, Jingjing; Jiang, Kyle; Pendry, John B; Zhang, Shuang

    2011-02-01

    Invisibility cloaks, which used to be confined to the realm of fiction, have now been turned into a scientific reality thanks to the enabling theoretical tools of transformation optics and conformal mapping. Inspired by those theoretical works, the experimental realization of electromagnetic invisibility cloaks has been reported at various electromagnetic frequencies. All the invisibility cloaks demonstrated thus far, however, have relied on nano- or micro-fabricated artificial composite materials with spatially varying electromagnetic properties, which limit the size of the cloaked region to a few wavelengths. Here, we report the first realization of a macroscopic volumetric invisibility cloak constructed from natural birefringent crystals. The cloak operates at visible frequencies and is capable of hiding, for a specific light polarization, three-dimensional objects of the scale of centimetres and millimetres. Our work opens avenues for future applications with macroscopic cloaking devices.

  5. Macroscopic quantum mechanics in a classical spacetime.

    PubMed

    Yang, Huan; Miao, Haixing; Lee, Da-Shin; Helou, Bassam; Chen, Yanbei

    2013-04-26

    We apply the many-particle Schrödinger-Newton equation, which describes the coevolution of a many-particle quantum wave function and a classical space-time geometry, to macroscopic mechanical objects. By averaging over motions of the objects' internal degrees of freedom, we obtain an effective Schrödinger-Newton equation for their centers of mass, which can be monitored and manipulated at quantum levels by state-of-the-art optomechanics experiments. For a single macroscopic object moving quantum mechanically within a harmonic potential well, its quantum uncertainty is found to evolve at a frequency different from its classical eigenfrequency-with a difference that depends on the internal structure of the object-and can be observable using current technology. For several objects, the Schrödinger-Newton equation predicts semiclassical motions just like Newtonian physics, yet quantum uncertainty cannot be transferred from one object to another.

  6. Probing Macroscopic Realism via Ramsey Correlation Measurements

    NASA Astrophysics Data System (ADS)

    Asadian, A.; Brukner, C.; Rabl, P.

    2014-05-01

    We describe a new and experimentally feasible protocol for performing fundamental tests of quantum mechanics with massive objects. In our approach, a single two-level system is used to probe the motion of a nanomechanical resonator via multiple Ramsey interference measurements. This scheme enables the measurement of modular variables of macroscopic continuous-variable systems; we show that correlations thereof violate a Leggett-Garg inequality and can be applied for tests of quantum contextuality. Our method can be implemented with a variety of different solid-state or photonic qubit-resonator systems, and it provides a clear experimental signature to distinguish the predictions of quantum mechanics from those of other alternative theories at a macroscopic scale.

  7. Macroscopic Invisibility Cloak for Visible Light

    NASA Astrophysics Data System (ADS)

    Zhang, Baile; Luo, Yuan; Liu, Xiaogang; Barbastathis, George

    2011-01-01

    Invisibility cloaks, a subject that usually occurs in science fiction and myths, have attracted wide interest recently because of their possible realization. The biggest challenge to true invisibility is known to be the cloaking of a macroscopic object in the broad range of wavelengths visible to the human eye. Here we experimentally solve this problem by incorporating the principle of transformation optics into a conventional optical lens fabrication with low-cost materials and simple manufacturing techniques. A transparent cloak made of two pieces of calcite is created. This cloak is able to conceal a macroscopic object with a maximum height of 2 mm, larger than 3500 free-space-wavelength, inside a transparent liquid environment. Its working bandwidth encompassing red, green, and blue light is also demonstrated.

  8. Effects of feeding a spray-dried multivalent polyclonal antibody preparation on feedlot performance, feeding behavior, carcass characteristics, rumenitis, and blood gas profile of Brangus and Nellore yearling bulls.

    PubMed

    Millen, D D; Pacheco, R D L; DiLorenzo, N; Martins, C L; Marino, C T; Bastos, J P S T; Mariani, T M; Barducci, R S; Sarti, L M N; DiCostanzo, A; Rodrigues, P H M; Arrigoni, M D B

    2015-09-01

    The objective of this study was to evaluate the effects of replacing monensin (MON) with a spray-dried multivalent polyclonal antibody preparation (PAP) against several ruminal microorganisms on feedlot performance, carcass characteristics, feeding behavior, blood gas profile, and the rumenitis incidence of Brangus and Nellore yearling bulls. The study was designed as a completely randomized design with a 2 × 2 factorial arrangement, replicated 6 times (4 bulls per pen and a total of 24 pens), in which bulls ( = 48) of each biotype were fed diets containing either MON fed at 300 mg/d or PAP fed at 3 g/d. No significant feed additive main effects were observed for ADG ( = 0.27), G:F ( = 0.28), HCW ( = 0.99), or dressing percentage ( = 0.80). However, bulls receiving PAP had greater DMI ( = 0.02) and larger ( = 0.02) final LM area as well as greater ( < 0.01) blood concentrations of bicarbonate and base excess in the extracellular fluid than bulls receiving MON. Brangus bulls had greater ( < 0.01) ADG and DMI expressed in kilograms, final BW, heavier HCW, and larger initial and final LM area than Nellore bulls. However, Nellore bulls had greater daily DMI fluctuation ( < 0.01), expressed as a percentage, and greater incidence of rumenitis ( = 0.05) than Brangus bulls. In addition, Brangus bulls had greater ( < 0.01) DMI per meal and also presented lower ( < 0.01) DM and NDF rumination rates when compared with Nellore bulls. Significant interactions ( < 0.05) between biotype and feed additive were observed for SFA, unsaturated fatty acids (UFA), MUFA, and PUFA concentrations in adipose tissues. When Nellore bulls were fed PAP, fat had greater ( < 0.05) SFA and PUFA contents but less ( < 0.01) UFA and MUFA than Nellore bulls receiving MON. For Brangus bulls, MON led to greater ( < 0.05) SFA and PUFA and less ( < 0.05) UFA and MUFA than Brangus bulls fed PAP. Feeding a spray-dried PAP led to similar feedlot performance compared with that when feeding MON. Spray

  9. Quantum Communication Using Macroscopic Phase Entangled States

    DTIC Science & Technology

    2015-12-10

    goals of our program was to investigate several different ways in which to implement the Kerr medium that allows a single photon to change the phase ...E7(/(3+21(180%(5 ,QFOXGHDUHDFRGH 1 i. Quantum Communication Using Macroscopic Phase Entangled States Final Report Reporting...media that can produce a shift in the phase of a laser pulse provided that a single photon from another source and at a different frequency is also

  10. Evaluation of arthroscopy and macroscopic scoring

    PubMed Central

    af Klint, Erik; Catrina, Anca I; Matt, Peter; Neregråd, Petra; Lampa, Jon; Ulfgren, Ann-Kristin; Klareskog, Lars; Lindblad, Staffan

    2009-01-01

    Introduction Arthroscopy is a minimally invasive technique for retrieving synovial biopsies in rheumatology during the past 20 years. Vital for its use is continual evaluation of its safety and efficacy. Important for sampling is the fact of intraarticular variation for synovial markers. For microscopic measurements scoring systems have been developed and validated, but for macroscopic evaluations there is a need for further comprehensive description and validation of equivalent scoring systems. Methods We studied the complication rate and yield of arthroscopies performed at our clinic between 1998 and 2005. We also created and evaluated a macroscopic score set of instructions for synovitis. Results Of 408 procedures, we had two major and one minor complication; two haemarthrosis and one wound infection, respectively. Pain was most often not a problem, but 12 procedures had to be prematurely ended due to pain. Yield of biopsies adequate for histology were 83% over all, 94% for knee joints and 34% for smaller joints. Video printer photographs of synovium taken during arthroscopy were jointly and individually reviewed by seven raters in several settings, and intra and inter rater variation was calculated. A macroscopic synovial scoring system for arthroscopy was created (Macro-score), based upon hypertrophy, vascularity and global synovitis. These written instructions were evaluated by five control-raters, and when evaluated individual parameters were without greater intra or inter rater variability, indicating that the score is reliable and easy to use. Conclusions In our hands rheumatologic arthroscopy is a safe method with very few complications. For knee joints it is a reliable method to retrieve representative tissue in clinical longitudinal studies. We also created an easy to use macroscopic score, that needs to be validated against other methodologies. We hope it will be of value in further developing international standards in this area. PMID:19490631

  11. Testing quantum behaviour at the macroscopic level

    NASA Astrophysics Data System (ADS)

    Ghirardi, Giancarlo

    1994-07-01

    We reconsider recent proposals to test macro realism versus quantum mechanics in experiments involving noninvasive measurement processes on a Squid. In spite of the fact that we are able to prove that the proposed experiments do not represent a test of macro realism but simply of macroscopic quantum coherence we call attention to their extreme conceptual relevance. We also discuss some recent criticisms which have been raised against the considered proposal and we show that they are not relevant.

  12. Polarization properties of macroscopic Bell states

    SciTech Connect

    Iskhakov, Timur Sh.; Chekhova, Maria V.; Leuchs, Gerd

    2011-10-15

    The four two-photon polarization Bell states are one of the main instruments in the toolbox of quantum optics and quantum information. In our experiment we produce their multiphoton counterparts, macroscopic Bell states. These are relevant to applications in quantum technologies because they provide efficient interactions with material quantum objects and with each other via nonlinear interactions. Furthermore, we study the polarization properties of these states using the concept of second-order degree of polarization and its higher-order generalization.

  13. Shot Noise in Linear Macroscopic Resistors

    NASA Astrophysics Data System (ADS)

    Gomila, G.; Pennetta, C.; Reggiani, L.; Sampietro, M.; Ferrari, G.; Bertuccio, G.

    2004-06-01

    We report on direct experimental evidence of shot noise in a linear macroscopic resistor. The origin of the shot noise comes from the fluctuation of the total number of charge carriers inside the resistor associated with their diffusive motion under the condition that the dielectric relaxation time becomes longer than the dynamic transit time. The present results show that neither potential barriers nor the absence of inelastic scattering are necessary to observe shot noise in electronic devices.

  14. Active Polar Two-Fluid Macroscopic Dynamics

    NASA Astrophysics Data System (ADS)

    Pleiner, Harald; Svensek, Daniel; Brand, Helmut R.

    2014-03-01

    We study the dynamics of systems with a polar dynamic preferred direction. Examples include the pattern-forming growth of bacteria (in a solvent, shoals of fish (moving in water currents), flocks of birds and migrating insects (flying in windy air). Because the preferred direction only exists dynamically, but not statically, the macroscopic variable of choice is the macroscopic velocity associated with the motion of the active units. We derive the macroscopic equations for such a system and discuss novel static, reversible and irreversible cross-couplings connected to this second velocity. We find a normal mode structure quite different compared to the static descriptions, as well as linear couplings between (active) flow and e.g. densities and concentrations due to the genuine two-fluid transport derivatives. On the other hand, we get, quite similar to the static case, a direct linear relation between the stress tensor and the structure tensor. This prominent ``active'' term is responsible for many active effects, meaning that our approach can describe those effects as well. In addition, we also deal with explicitly chiral systems, which are important for many active systems. In particular, we find an active flow-induced heat current specific for the dynamic chiral polar order.

  15. Percolation and hysteresis in macroscopic capillarity

    NASA Astrophysics Data System (ADS)

    Hilfer, Rudolf

    2010-05-01

    The concepts of relative permeability and capillary pressure are crucial for the accepted traditional theory of two phase flow in porous media. Recently a theoretical approach was introduced that does not require these concepts as input [1][2][3]. Instead it was based on the concept of hydraulic percolation of fluid phases. The presentation will describe this novel approach. It allows to simulate processes with simultaneous occurence of drainage and imbibition. Furthermore, it predicts residual saturations and their spatiotemporal changes during two phase immiscible displacement [1][2][3][4][5]. [1] R. Hilfer. Capillary Pressure, Hysteresis and Residual Saturation in Porous Media, Physica A, vol. 359, pp. 119, 2006. [2] R. Hilfer. Macroscopic Capillarity and Hysteresis for Flow in Porous Media, Physical Review E, vol. 73, pp. 016307, 2006. [3] R. Hilfer. Macroscopic capillarity without a constitutive capillary pressure function, Physica A, vol. 371, pp. 209, 2006. [4] R. Hilfer. Modeling and Simulation of Macrocapillarity, in: P. Garrido et al. (eds.) Modeling and Simulation of Materials vol. CP1091, pp. 141, American Institute of Physcis, New York, 2009. [5] R. Hilfer and F. Doster. Percolation as a basic concept for macroscopic capillarity, Transport in Porous Media, DOI 10.1007/s11242-009-9395-0, in print, 2009.

  16. Miniature spray-painting booth

    NASA Technical Reports Server (NTRS)

    Fee, K. W.

    1970-01-01

    Transparent spray booth provides method for quality painting and repair of surfaces in clean room or other specialized environments. Overspray and virtually all contaminating vapor and odor can be eliminated. Touch-up painting is achieved with spray gun.

  17. Nasal spray flu vaccine (image)

    MedlinePlus

    The flu vaccine can also be administered as a nasal spray instead of the usual injection method. It can be ... the recombinant influenza vaccine (RIV). The nasal spray flu vaccine (live attenuated influenza vaccine or LAIV) should not ...

  18. [Study on Xinyueshu spray drying assisted with copovidone and its effect on powder property].

    PubMed

    Jiang, Yan-Rong; Zhang, Zhen-Hai; Ding, Dong-Mei; Yan, Hong-Mei; Hu, Shao-Ying; Jia, Xiao-Bin

    2013-12-01

    To study the application characteristics of copovidone (PVP-S630) in Xinyueshu extracts during the spray drying process, and its effect on such pharmaceutical properties as micromeritics and drug release behavior. PVP-S630 was added into Xinyueshu extracts to study on the spray drying, the effect of different dosages of PVP-S630 against the wall sticking effect of the spray drying, as well as the power property of Xinyueshu spray drying power and the dissolution in vitro behavior of the effective component of hyperoside. The results showed that PVP-S630 revealed a significant anti-wall sticking effect, with no notable change in the grain size of the spray drying power, increase in the fluidity, improvement in the moisture absorption and remarkable rise in the dissolution in vitro behavior of hyperoside. It was worth further studying the application of PVP-S630 in spray drying power of traditional Chinese medicine.

  19. Pathways toward understanding Macroscopic Quantum Phenomena

    NASA Astrophysics Data System (ADS)

    Hu, B. L.; Subaşi, Y.

    2013-06-01

    Macroscopic quantum phenomena refer to quantum features in objects of 'large' sizes, systems with many components or degrees of freedom, organized in some ways where they can be identified as macroscopic objects. This emerging field is ushered in by several categories of definitive experiments in superconductivity, electromechanical systems, Bose-Einstein condensates and others. Yet this new field which is rich in open issues at the foundation of quantum and statistical physics remains little explored theoretically (with the important exception of the work of A J Leggett [1], while touched upon or implied by several groups of authors represented in this conference. Our attitude differs in that we believe in the full validity of quantum mechanics stretching from the testable micro to meso scales, with no need for the introduction of new laws of physics.) This talk summarizes our thoughts in attempting a systematic investigation into some key foundational issues of quantum macroscopic phenomena, with the goal of ultimately revealing or building a viable theoretical framework. Three major themes discussed in three intended essays are the large N expansion [2], the correlation hierarchy [3] and quantum entanglement [4]. We give a sketch of the first two themes and then discuss several key issues in the consideration of macro and quantum, namely, a) recognition that there exist many levels of structure in a composite body and only by judicious choice of an appropriate set of collective variables can one give the best description of the dynamics of a specific level of structure. Capturing the quantum features of a macroscopic object is greatly facilitated by the existence and functioning of these collective variables; b) quantum entanglement, an exclusively quantum feature [5], is known to persist to high temperatures [6] and large scales [7] under certain conditions, and may actually decrease with increased connectivity in a quantum network [8]. We use entanglement as a

  20. Controlled overspray spray nozzle

    NASA Technical Reports Server (NTRS)

    Prasthofer, W. P. (Inventor)

    1981-01-01

    A spray system for a multi-ingredient ablative material wherein a nozzle A is utilized for suppressing overspray is described. The nozzle includes a cyclindrical inlet which converges to a restricted throat. A curved juncture between the cylindrical inlet and the convergent portion affords unrestricted and uninterrupted flow of the ablative material. A divergent bell-shaped chamber and adjustable nozzle exit B is utilized which provides a highly effective spray pattern in suppressing overspray to an acceptable level and producing a homogeneous jet of material that adheres well to the substrate.

  1. Micro- and macroscopic photonic control of matter

    NASA Astrophysics Data System (ADS)

    Ryabtsev, Anton

    This dissertation outlines the development of several methods and techniques that enable comprehensive control of laser-matter interactions and nonlinear optical processes using shaped femtosecond pulses. Manipulation of the spectral phases and amplitudes of femtosecond laser pulses provides an effective way to adjust laser parameters, both those intrinsic to pulse generation within a laser and those induced by laser-matter interactions. When coupled with a fundamental understanding of the interactions between a laser's electric field and the molecules in the propagation media, these methods make the behavior of laser pulses predictable and allow the experimental information they carry to be extracted accurately. The ultimate motivation is to enhance the accuracy and reproducibility of spectroscopic measurements and to control nonlinear processes during light-matter interaction using shaped femtosecond pulses. Ultrafast laser systems have become one of the most important scientific tools in femtochemistry, nanoscale material science, chemical detection and sensing, and many other applications where processes occur at femtosecond (fs, 10-15 of a second) timescales or when broad laser bandwidths are required. As with any measuring instrument, it is very important to know system's exact parameters in order to make meaningful, accurate and reproducible measurements. For ultrafast lasers, these parameters are the intensities of the spectral components, the spectral phase, the temporal profile, the pulse energy, and the spatial laser beam profile. Due to broadband nature of ultrafast laser sources, they are very sensitive to propagation media: gaseous, liquid or solid matter along the paths of laser pulses to the sample, including the material of the sample itself. Optical parameters describing the propagation media, such as linear and nonlinear dispersion, and birefringence, as well as physical parameters, such as temperature and pressure, all affect laser pulse

  2. Elastic response of thermal spray deposits under indentation tests

    SciTech Connect

    Leigh, S.H.; Lin, C.K.; Berndt, C.C.

    1997-08-01

    The elastic response behavior of thermal spray deposits at Knoop indentations has been investigated using indentation techniques. The ration of hardness to elastic modulus, which is an important prerequisite for the evaluation of indentation fracture toughness, is determined by measuring the elastic recovery of the in-surface dimensions of Knoop indentations. The elastic moduli of thermal spray deposits are in the range of 12%--78% of the comparable bulk materials and reveal the anisotropic behavior of thermal spray deposits. A variety of thermal spray deposits has been examined, including Al{sub 2}O{sub 3}, yttria-stabilized ZrO{sub 2} (YSZ), and NiAl. Statistical tools have been used to evaluate the error estimates of the data.

  3. Behaviors of MC3T3-E1 cells on carbonated apatite films, with a characteristic network structure, fabricated on a titanium plate by aqueous spray coating.

    PubMed

    Mochizuki, Chihiro; Hara, Hiroki; Oya, Kei; Aoki, Shun; Hayakawa, Tohru; Fujie, Hiromichi; Sato, Mitsunobu

    2014-06-01

    Four carbonated apatite films having average thicknesses of 1.3-0.11μm, proportions of network sizes above 10μm of 41-68%, and average border heights of the characteristic network structure of 0.98-0.29μm were fabricated on a titanium plate by aqueous spray coating. These carbonated apatite films after heat treatment showed good mineralization ability in Hanks' balanced salt solution. Assessment of initial cell attachment and calcination on these films and on the Ti plate using osteoblastic MC3T3-E1 indicated that the carbonated apatite film heat treated at 600°C, whose film thickness, proportion of network sizes above 10μm, and border height were 0.11μm, 61%, and 0.31μm, respectively, was most preferred by osteoblastic cells. Field emission scanning electron microscopic observation of the cells attached to the films showed that the wide network and low border height of the network structure on the carbonated apatite film play an important role in the development of the filopodia of the osteoblastic cells. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Duality in entanglement of macroscopic states of light

    NASA Astrophysics Data System (ADS)

    Lee, Su-Yong; Lee, Chang-Woo; Kurzyński, Paweł; Kaszlikowski, Dagomir; Kim, Jaewan

    2016-08-01

    We investigate duality in entanglement of a bipartite multiphoton system generated from a coherent state of light. The system can exhibit polarization entanglement if the two parts are distinguished by their parity, or parity entanglement if the parts are distinguished by polarization. It was shown in Phys. Rev. Lett. 110, 140404 (2013), 10.1103/PhysRevLett.110.140404 that this phenomenon can be exploited as a method to test indistinguishability of two particles and it was conjectured that one can also test indistinguishability of macroscopic systems. We propose a setup to test this conjecture. Contrary to the previous studies using two-particle interference effect as in the Hong-Ou- Mandel setup, our setup neither assumes that the tested state is composed of single particles nor requires that the total number of particles be fixed. Consequently, the notion of entanglement duality is shown to be compatible with a broader class of physical systems. Moreover, by observing duality in entanglement in the above system one can confirm that macroscopic systems exhibit quantum behavior. As a practical side, entanglement duality is a useful concept that enables adaptive conversion of entanglement of one degree of freedom (DOF) to that of another DOF according to varying quantum protocols.

  5. A macroscopic analytical model of collaboration in distributed robotic systems.

    PubMed

    Lerman, K; Galstyan, A; Martinoli, A; Ijspeert, A

    2001-01-01

    In this article, we present a macroscopic analytical model of collaboration in a group of reactive robots. The model consists of a series of coupled differential equations that describe the dynamics of group behavior. After presenting the general model, we analyze in detail a case study of collaboration, the stick-pulling experiment, studied experimentally and in simulation by Ijspeert et al. [Autonomous Robots, 11, 149-171]. The robots' task is to pull sticks out of their holes, and it can be successfully achieved only through the collaboration of two robots. There is no explicit communication or coordination between the robots. Unlike microscopic simulations (sensor-based or using a probabilistic numerical model), in which computational time scales with the robot group size, the macroscopic model is computationally efficient, because its solutions are independent of robot group size. Analysis reproduces several qualitative conclusions of Ijspeert et al.: namely, the different dynamical regimes for different values of the ratio of robots to sticks, the existence of optimal control parameters that maximize system performance as a function of group size, and the transition from superlinear to sublinear performance as the number of robots is increased.

  6. Microscopic and macroscopic instabilities in hyperelastic fiber composites

    NASA Astrophysics Data System (ADS)

    Slesarenko, Viacheslav; Rudykh, Stephan

    2017-02-01

    In this paper, we study the interplay between macroscopic and microscopic instabilities in 3D periodic fiber reinforced composites undergoing large deformations. We employ the Bloch-Floquet analysis to determine the onset of microscopic instabilities for composites with hyperelastic constituents. We show that the primary mode of buckling in the fiber composites is determined by the volume fraction of fibers and the contrast between elastic moduli of fiber and matrix phases. We find that for composites with volume fraction of fibers exceeding a threshold value, which depends on elastic modulus contrast, the primary buckling mode corresponds to the long wave or macroscopic instability. However, composites with a lower amount of fibers experience microscopic instabilities corresponding to wavy or helical buckling shapes. Buckling modes and critical wavelengths are shown to be highly tunable by material composition. A comparison between the instability behavior of 3D fiber composites and laminates, subjected to uniaxial compression, reveals the significant differences in critical strains, wavelengths, and transition points from macro- to microscopic instabilities in these composites.

  7. Sprayed Coating Renews Butyl Rubber

    NASA Technical Reports Server (NTRS)

    Martin, R. B.

    1982-01-01

    Damaged butyl rubber products are renewed by spray technique originally developed for protective suits worn by NASA workers. A commercial two-part adhesive is mixed with Freon-113 (or equivalent) trichlorotrifluoroethane to obtain optimum viscosity for spraying. Mix is applied with an external-air-mix spray gun.

  8. Picosecond imaging of sprays

    NASA Technical Reports Server (NTRS)

    Breisacher, Kevin; Liou, Larry; Wang, L.; Liang, X.; Galland, P.; Ho, P. P.; Alfano, R. R.

    1994-01-01

    Preliminary results from applying a Kerr-Fourier imaging system to a water/air spray produced by a shear coaxial element are presented. The physics behind ultrafast time-gated optical techniques is discussed briefly. A typical setup of a Kerr-Fourier time gating system is presented.

  9. Oxymetazoline Nasal Spray

    MedlinePlus

    ... Rinse the tip of the dispenser with hot water or wipe it clean after you use it.Follow the directions for using the nasal spray that appear on the package label. If you are using a product that comes in a pump dispenser, press down on the rim several times ...

  10. Ocean Spray Lubricates Winds

    ERIC Educational Resources Information Center

    Journal of College Science Teaching, 2005

    2005-01-01

    According to a new study by two University of California, Berkeley, mathematicians and their Russian colleague, the water droplets kicked up by rough seas serve to lubricate the swirling winds of hurricanes and cyclones, letting them build to speeds approaching 200 miles per hour. Without the lubricating effect of the spray, the mathematicians…

  11. Ocean Spray Lubricates Winds

    ERIC Educational Resources Information Center

    Journal of College Science Teaching, 2005

    2005-01-01

    According to a new study by two University of California, Berkeley, mathematicians and their Russian colleague, the water droplets kicked up by rough seas serve to lubricate the swirling winds of hurricanes and cyclones, letting them build to speeds approaching 200 miles per hour. Without the lubricating effect of the spray, the mathematicians…

  12. Mometasone Nasal Spray

    MedlinePlus

    ... in cold water and rinse them in cold water, let them dry at room temperature, and then put them back on the bottle.If the spray tip is clogged, wash it in cold water and then rinse it in cold water and ...

  13. Spray combustion stability project

    NASA Technical Reports Server (NTRS)

    Jeng, San-Mou; Litchford, Ron J.

    1992-01-01

    This report summarizes research activity on the Spray Combustion Stability Project, characterizes accomplishments and current status, and discusses projected future work. The purpose is to provide a concise conceptual overview of the research effort to date so the reader can quickly assimilate the gist of the research results and place them within the context of their potential impact on liquid rocket engine design technology.

  14. Caracterisation of Titanium Nitride Layers Deposited by Reactive Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Roşu, Radu Alexandru; Şerban, Viorel-Aurel; Bucur, Alexandra Ioana; Popescu, Mihaela; Uţu, Dragoş

    2011-01-01

    Forming and cutting tools are subjected to the intense wear solicitations. Usually, they are either subject to superficial heat treatments or are covered with various materials with high mechanical properties. In recent years, thermal spraying is used increasingly in engineering area because of the large range of materials that can be used for the coatings. Titanium nitride is a ceramic material with high hardness which is used to cover the cutting tools increasing their lifetime. The paper presents the results obtained after deposition of titanium nitride layers by reactive plasma spraying (RPS). As deposition material was used titanium powder and as substratum was used titanium alloy (Ti6Al4V). Macroscopic and microscopic (scanning electron microscopy) images of the deposited layers and the X ray diffraction of the coatings are presented. Demonstration program with layers deposited with thickness between 68,5 and 81,4 μm has been achieved and presented.

  15. General framework for quantum macroscopicity in terms of coherence

    NASA Astrophysics Data System (ADS)

    Yadin, Benjamin; Vedral, Vlatko

    2016-02-01

    We propose a universal language to assess macroscopic quantumness in terms of coherence, with a set of conditions that should be satisfied by any measure of macroscopic coherence. We link the framework to the resource theory of asymmetry. We show that the quantum Fisher information gives a good measure of macroscopic coherence, enabling a rigorous justification of a previously proposed measure of macroscopicity. This picture lets us draw connections between different measures of macroscopicity and evaluate them; we show that another widely studied measure fails one of our criteria.

  16. Macroscopic Two-Dimensional Polariton Condensates

    NASA Astrophysics Data System (ADS)

    Ballarini, Dario; Caputo, Davide; Muñoz, Carlos Sánchez; De Giorgi, Milena; Dominici, Lorenzo; Szymańska, Marzena H.; West, Kenneth; Pfeiffer, Loren N.; Gigli, Giuseppe; Laussy, Fabrice P.; Sanvitto, Daniele

    2017-05-01

    We report a record-size, two-dimensional polariton condensate of a fraction of a millimeter radius free from the presence of an exciton reservoir. This macroscopically occupied state is formed by the ballistically expanding polariton flow that relaxes and condenses over a large area outside of the excitation spot. The density of this trap-free condensate is <1 polariton /μ m2 , reducing the phase noise induced by the interaction energy. Moreover, the backflow effect, recently predicted for the nonparabolic polariton dispersion, is observed here for the first time in the fast-expanding wave packet.

  17. Observation of complementarity in the macroscopic domain

    SciTech Connect

    Cao Dezhong; Xiong Jun; Tang Hua; Lin Lufang; Zhang Suheng; Wang Kaige

    2007-09-15

    Complementarity is usually considered as a phenomenon of microscopic systems. In this paper, we report an experimental observation of complementarity in correlated double-slit interference with a pseudothermal light source. The thermal light beam is divided into test and reference beams which are correlated with each other. The double slit is set in the test arm, and an interference pattern can be observed in the intensity correlation between the two arms. The experimental results show that the disappearance of the interference fringe depends on whether which-path information is gained through the reference arm. The experiment therefore shows complementarity occurring in the macroscopic domain.

  18. Relating Macroscopic Thermal Phenomena with Molecular Models

    NASA Astrophysics Data System (ADS)

    Laws, Priscilla W.

    2002-03-01

    A series of observations and activities have been developed to help students enrich their understanding of how physicists can use model building to construct self-consistent models of physical reality.* This talk will describe the instructional use of integrated microcomputer-based laboratory measurements of macroscopic phenomena and digital video analysis of simulated microscopic events to help students understand the ideal gas law, the first law of thermodynamics, and heat engines. *Workshop Physics Activity Guide (Module 3), P. Laws, (John Wiley and Sons, Inc., NY, 1997).

  19. Compressor Has No Moving Macroscopic Parts

    NASA Technical Reports Server (NTRS)

    Gasser, Max

    1995-01-01

    Compressor containing no moving macroscopic parts functions by alternating piston and valve actions of successive beds of magnetic particles. Fabricated easily because no need for precisely fitting parts rotating or sliding on each other. Also no need for lubricant fluid contaminating fluid to be compressed. Compressor operates continuously, eliminating troublesome on/off cycling of other compressors, and decreasing consumption of energy. Phased cells push fluid from bottom to top, adding increments of pressure. Each cell contains magnetic powder particles loose when electromagnet coil deenergized, but tightly packed when coil energized.

  20. Compressor Has No Moving Macroscopic Parts

    NASA Technical Reports Server (NTRS)

    Gasser, Max

    1995-01-01

    Compressor containing no moving macroscopic parts functions by alternating piston and valve actions of successive beds of magnetic particles. Fabricated easily because no need for precisely fitting parts rotating or sliding on each other. Also no need for lubricant fluid contaminating fluid to be compressed. Compressor operates continuously, eliminating troublesome on/off cycling of other compressors, and decreasing consumption of energy. Phased cells push fluid from bottom to top, adding increments of pressure. Each cell contains magnetic powder particles loose when electromagnet coil deenergized, but tightly packed when coil energized.

  1. Rainbow correlation imaging with macroscopic twin beam

    NASA Astrophysics Data System (ADS)

    Allevi, Alessia; Bondani, Maria

    2017-06-01

    We present the implementation of a correlation-imaging protocol that exploits both the spatial and spectral correlations of macroscopic twin-beam states generated by parametric downconversion. In particular, the spectral resolution of an imaging spectrometer coupled to an EMCCD camera is used in a proof-of-principle experiment to encrypt and decrypt a simple code to be transmitted between two parties. In order to optimize the trade-off between visibility and resolution, we provide the characterization of the correlation images as a function of the spatio-spectral properties of twin beams generated at different pump power values.

  2. Macroscopic Two-Dimensional Polariton Condensates.

    PubMed

    Ballarini, Dario; Caputo, Davide; Muñoz, Carlos Sánchez; De Giorgi, Milena; Dominici, Lorenzo; Szymańska, Marzena H; West, Kenneth; Pfeiffer, Loren N; Gigli, Giuseppe; Laussy, Fabrice P; Sanvitto, Daniele

    2017-05-26

    We report a record-size, two-dimensional polariton condensate of a fraction of a millimeter radius free from the presence of an exciton reservoir. This macroscopically occupied state is formed by the ballistically expanding polariton flow that relaxes and condenses over a large area outside of the excitation spot. The density of this trap-free condensate is <1  polariton/μm^{2}, reducing the phase noise induced by the interaction energy. Moreover, the backflow effect, recently predicted for the nonparabolic polariton dispersion, is observed here for the first time in the fast-expanding wave packet.

  3. Thermal spray for commercial shipbuilding

    NASA Astrophysics Data System (ADS)

    Rogers, F. S.

    1997-09-01

    Thermal spraying of steel with aluminum to protect it from corrosion is a technology that has been proven to work in the marine environment. The thermal spray coating system includes a paint sealer that is applied over the thermally sprayed aluminum. This extends the service life of the coating and provides color to the end product. The thermal spray system protects steel both through the principle of isolation (as in painting) and galvanizing. With this dual protection mechanism, steel is protected from corrosion even when the coating is damaged. The thermal- sprayed aluminum coating system has proved the most cost- effective corrosion protection system for the marine environment. Until recently, however, the initial cost of application has limited its use for general application. Arc spray technology has reduced the application cost of thermal spraying of aluminum to below that of painting. Commercial shipbuilders could use this technology to enhance their market position in the marine industry.

  4. Macroscopic quantum entanglement of a Kondo cloud at finite temperature.

    PubMed

    Lee, S-S B; Park, Jinhong; Sim, H-S

    2015-02-06

    We propose a variational approach for computing the macroscopic entanglement in a many-body mixed state, based on entanglement witness operators, and compute the entanglement of formation (EoF), a mixed-state generalization of the entanglement entropy, in single- and two-channel Kondo systems at finite temperature. The thermal suppression of the EoF obeys power-law scaling at low temperature. The scaling exponent is halved from the single- to the two-channel system, which is attributed, using a bosonization method, to the non-Fermi liquid behavior of a Majorana fermion, a "half" of a complex fermion, emerging in the two-channel system. Moreover, the EoF characterizes the size and power-law tail of the Kondo screening cloud of the single-channel system.

  5. Tunable Broadband Transparency of Macroscopic Quantum Superconducting Metamaterials

    NASA Astrophysics Data System (ADS)

    Zhang, Daimeng; Trepanier, Melissa; Mukhanov, Oleg; Anlage, Steven M.

    2015-10-01

    Narrow-band invisibility in an otherwise opaque medium has been achieved by electromagnetically induced transparency (EIT) in atomic systems. The quantum EIT behavior can be classically mimicked by specially engineered metamaterials via carefully controlled interference with a "dark mode." However, the narrow transparency window limits the potential applications that require a tunable wideband transparent performance. Here, we present a macroscopic quantum superconducting metamaterial with manipulative self-induced broadband transparency due to a qualitatively novel nonlinear mechanism that is different from conventional EIT or its classical analogs. A near-complete disappearance of resonant absorption under a range of applied rf flux is observed experimentally and explained theoretically. The transparency comes from the intrinsic bistability of the meta-atoms and can be tuned on and off easily by altering rf and dc magnetic fields, temperature, and history. Hysteretic in situ 100% tunability of transparency paves the way for autocloaking metamaterials, intensity-dependent filters, and fast-tunable power limiters.

  6. Superfluid Helium from the Macroscopic to the Microscopic

    SciTech Connect

    Van Sciver, Steven W. (Florida State University

    2004-02-11

    Superfluid helium, first discovered in the 1930s, continues to provide scientists with a fascinating physical system rich with phenomena that challenge experimental and theoretical investigators. Moreover, much of the recent interest in superfluid helium has emanated from the wide range of technical applications for the fluid. The combination of anomalous heat transport, low viscosity and low temperature makes superfluid helium an ideal medium for cooling technologies that range from particle accelerators such as the LHC to space infrared telescopes like the recently launched SIRTF. In turn, these applications have inspired new basic investigations of the fluid dynamic behavior of superfluid helium. The presentation will review some of the macroscopic applications for superfluid helium and the relevant superfluid phenomena that support these applications. With the audience sufficiently motivated, we will turn to recent research on the transport properties of superfluid helium culminating in microscale investigations that may provide new insight into the basic physics of superfluid helium.

  7. Macroscopic quantum self-trapping in dynamical tunneling.

    PubMed

    Wüster, Sebastian; Dąbrowska-Wüster, Beata J; Dabrowska-Wüster, Beata J; Davis, Matthew J

    2012-08-24

    It is well known that increasing the nonlinearity due to repulsive atomic interactions in a double-well Bose-Einstein condensate suppresses quantum tunneling between the two sites. Here we find analogous behavior in the dynamical tunneling of a Bose-Einstein condensate between period-one resonances in a single driven potential well. For small nonlinearities we find unhindered tunneling between the resonances, but with an increasing period as compared to the noninteracting system. For nonlinearities above a critical value we generally observe that the tunneling shuts down. However, for certain regimes of modulation parameters we find that dynamical tunneling reemerges for large enough nonlinearities, an effect not present in spatial double-well tunneling. We develop a two-mode model in good agreement with full numerical simulations over a wide range of parameters, which allows the suppression of tunneling to be attributed to macroscopic quantum self-trapping.

  8. Bouncing droplets: a classroom experiment to visualize wave-particle duality on the macroscopic level

    NASA Astrophysics Data System (ADS)

    Sleutel, Pascal; Dietrich, Erik; Van der Veen, Jan T.; van Joolingen, Wouter R.

    2016-09-01

    This study brings a recently discovered macroscopic phenomenon with wave-particle characteristics into the classroom. The system consists of a liquid droplet levitating over a vertically shaken liquid pool. The droplets allow visualization of a wave-particle system in a directly observable way. We show how to interpret this macroscopic phenomenon and how to set up and carry out this experiment. A class of students performed single slit diffraction experiments with droplets. By scoring individual droplet trajectories students find a diffraction pattern. This pilot application in the classroom shows that students can study and discuss the wave-particle nature of the bouncing droplet experiment. The experiment therefore provides a useful opportunity to show wave-particle behavior on the macroscopic level.

  9. Spin models as microfoundation of macroscopic market models

    NASA Astrophysics Data System (ADS)

    Krause, Sebastian M.; Bornholdt, Stefan

    2013-09-01

    Macroscopic price evolution models are commonly used for investment strategies. There are first promising achievements in defining microscopic agent based models for the same purpose. Microscopic models allow a deeper understanding of mechanisms in the market than the purely phenomenological macroscopic models, and thus bear the chance for better models for market regulation. However microscopic models and macroscopic models are commonly studied separately. Here, we exemplify a unified view of a microscopic and a macroscopic market model in a case study, deducing a macroscopic Langevin equation from a microscopic spin market model closely related to the Ising model. The interplay of the microscopic and the macroscopic view allows for a better understanding and adjustment of the microscopic model, as well, and may guide the construction of agent based market models as basis of macroscopic models.

  10. Improved Orifice Plate for Spray Gun

    NASA Technical Reports Server (NTRS)

    Cunningham, W.

    1986-01-01

    Erratic spray pattern of commercial spray gun changed to repeatable one by simple redesign of two parts. In modified spray gun orifice plate and polytetrafluoroethylene bushing redesigned to assure centering and alignment with nozzle. Such improvement useful in many industrial applications requiring repeatable spray patterns. Might include spraying of foam insulation, paint, other protective coatings, detergents, abrasives, adhesives, process chemicals, or fuels. Unmodified spray gun produces erratic spray because lateral misalignment between orifice plate and nozzle.

  11. Improved Orifice Plate for Spray Gun

    NASA Technical Reports Server (NTRS)

    Cunningham, W.

    1986-01-01

    Erratic spray pattern of commercial spray gun changed to repeatable one by simple redesign of two parts. In modified spray gun orifice plate and polytetrafluoroethylene bushing redesigned to assure centering and alignment with nozzle. Such improvement useful in many industrial applications requiring repeatable spray patterns. Might include spraying of foam insulation, paint, other protective coatings, detergents, abrasives, adhesives, process chemicals, or fuels. Unmodified spray gun produces erratic spray because lateral misalignment between orifice plate and nozzle.

  12. Optimisation of a vertical spray boom for greenhouse spraying applications.

    PubMed

    Nuyttens, D; Windey, S; Braekman, P; De Moor, A; Sonck, B

    2003-01-01

    The European Crop Protection Association (ECPA) and CLO-DVL joined forces in a project to stimulate a safe use of pesticides in Southern European countries. CLO-DVL optimised a method with mineral chelates to evaluate deposition tests. This quantitative method to evaluate spray deposits and to check spray distributions is used to assess two novel spraying techniques. Deposition tests with water-sensitive paper and mainly with the manganese and molybdenum chelates as tracer elements were performed with a manually pulled trolley and a motorised vehicle both equipped with vertical spray booms. Filter papers were attached to the tomato and pepper plants at several heights to obtain an indication of the spray distribution in the crop. Particular attention was paid to the effect on the spray distribution of the vertical nozzle distance (35 cm vs. 50 cm) and the spray distance to the crop. The tests proved that a nozzle spacing of 35 cm delivers a much better spray distribution than one of 50 cm. The optimal spray distance for flat fan nozzles with a spray angle of 80 degrees and a nozzle spacing of 35 cm is about 30 cm.

  13. Tough and Thermosensitive Poly(N-isopropylacrylamide)/Graphene Oxide Hydrogels with Macroscopically Oriented Liquid Crystalline Structures.

    PubMed

    Zhu, Zhongcheng; Li, Yang; Xu, Hui; Peng, Xin; Chen, Ya-Nan; Shang, Cong; Zhang, Qin; Liu, Jiaqi; Wang, Huiliang

    2016-06-22

    Bulk graphene oxide (GO) nanocomposite materials with macroscopically oriented GO liquid crystalline (LC) structures exhibit interesting anisotropic properties, but their facile preparations remain challenging. This work reports for the first time the facile preparation of poly(N-isopropylacrylamide) (PNIPAM)/GO nanocomposite hydrogels with macroscopically oriented LC structures with the assistance of a flow field induced by vacuum degassing and the in situ polymerization accelerated by GO. The hydrogel prepared with a GO concentration of 5.0 mg mL(-1) exhibits macroscopically aligned LC structures, which endow the gels with anisotropic optical, mechanical properties, and dimensional changes during the phase transition. The hydrogels show dramatically enhanced tensile mechanical properties and phase transition rates. The oriented LC structures are not damaged during the phase transition of the PNIPAM/GO hydrogels, and hence their LC behavior undergoes reversible change. Moreover, highly oriented LC structures can also be formed when the gels are elongated, even for the gels which do not have macroscopically oriented LC structures. Very impressively, the oriented LC structures in the hydrogels can be permanently maintained by drying the gel samples elongated to and then kept at a constant tensile strain. The thermosensitive nature of PNIPAM and the angle-dependent nature of the macroscopically aligned GO LC structures allow the practical applications of the PNIPAM/GO hydrogels as optical switches, soft sensors, and actuators and so on.

  14. Uncovering low dimensional macroscopic chaotic dynamics of large finite size complex systems

    NASA Astrophysics Data System (ADS)

    Skardal, Per Sebastian; Restrepo, Juan G.; Ott, Edward

    2017-08-01

    In the last decade, it has been shown that a large class of phase oscillator models admit low dimensional descriptions for the macroscopic system dynamics in the limit of an infinite number N of oscillators. The question of whether the macroscopic dynamics of other similar systems also have a low dimensional description in the infinite N limit has, however, remained elusive. In this paper, we show how techniques originally designed to analyze noisy experimental chaotic time series can be used to identify effective low dimensional macroscopic descriptions from simulations with a finite number of elements. We illustrate and verify the effectiveness of our approach by applying it to the dynamics of an ensemble of globally coupled Landau-Stuart oscillators for which we demonstrate low dimensional macroscopic chaotic behavior with an effective 4-dimensional description. By using this description, we show that one can calculate dynamical invariants such as Lyapunov exponents and attractor dimensions. One could also use the reconstruction to generate short-term predictions of the macroscopic dynamics.

  15. Assessing Macroscopic Evapotranspiration Function Response to Climate

    NASA Astrophysics Data System (ADS)

    Gharun, M.; Vervoort, R. W.; Turnbull, T.; Henry, J.; Adams, M.

    2012-12-01

    Evapotranspiration (ET) by forests can reach up to 100% of rainfall in Australia, and is a substantial component of the water balance. Transpiration is a major part of the ET and it is well-known that transpiration depends on a combination of physiological and environmental controls. As a consequence of well-ventilated canopies of eucalypt forests and close decoupling to the atmosphere, atmospheric conditions exert a large control over transpiration. We measured a suit of environmental variables including temperature, humidity, radiation, and soil moisture concurrently with transpiration in a range of eucalypt forests. We observed that atmospheric demand (VPD) exerts the strongest control over transpiration. Experimental evidence also showed a strong dependency of the control on soil moisture abundance in the top soil layer. In many eco-hydrological models actual ET is represented with a linear transformation of potential ET based on the soil moisture condition, a so-called macroscopic approach. Such ET functions lump various soil and plant factors, are not experimentally supported and therefore quite poorly validated. Different combinations of atmospheric demand and soil moisture availability lead to diverse behaviour of the macroscopic ET function. Based on our observations in this study, we propose a novel approach that improves portray of transpiration, evaporation, drainage and hence the loss of water from the root zone. We used a modified version of the Norwegian HBV model to test our approach over a medium size catchment (150 km2) in south east Australia.

  16. Deterministic Creation of Macroscopic Cat States

    PubMed Central

    Lombardo, Daniel; Twamley, Jason

    2015-01-01

    Despite current technological advances, observing quantum mechanical effects outside of the nanoscopic realm is extremely challenging. For this reason, the observation of such effects on larger scale systems is currently one of the most attractive goals in quantum science. Many experimental protocols have been proposed for both the creation and observation of quantum states on macroscopic scales, in particular, in the field of optomechanics. The majority of these proposals, however, rely on performing measurements, making them probabilistic. In this work we develop a completely deterministic method of macroscopic quantum state creation. We study the prototypical optomechanical Membrane In The Middle model and show that by controlling the membrane’s opacity, and through careful choice of the optical cavity initial state, we can deterministically create and grow the spatial extent of the membrane’s position into a large cat state. It is found that by using a Bose-Einstein condensate as a membrane high fidelity cat states with spatial separations of up to ∼300 nm can be achieved. PMID:26345157

  17. Macroscopic theory for capillary-pressure hysteresis.

    PubMed

    Athukorallage, Bhagya; Aulisa, Eugenio; Iyer, Ram; Zhang, Larry

    2015-03-03

    In this article, we present a theory of macroscopic contact angle hysteresis by considering the minimization of the Helmholtz free energy of a solid-liquid-gas system over a convex set, subject to a constant volume constraint. The liquid and solid surfaces in contact are assumed to adhere weakly to each other, causing the interfacial energy to be set-valued. A simple calculus of variations argument for the minimization of the Helmholtz energy leads to the Young-Laplace equation for the drop surface in contact with the gas and a variational inequality that yields contact angle hysteresis for advancing/receding flow. We also show that the Young-Laplace equation with a Dirichlet boundary condition together with the variational inequality yields a basic hysteresis operator that describes the relationship between capillary pressure and volume. We validate the theory using results from the experiment for a sessile macroscopic drop. Although the capillary effect is a complex phenomenon even for a droplet as various points along the contact line might be pinned, the capillary pressure and volume of the drop are scalar variables that encapsulate the global quasistatic energy information for the entire droplet. Studying the capillary pressure versus volume relationship greatly simplifies the understanding and modeling of the phenomenon just as scalar magnetic hysteresis graphs greatly aided the modeling of devices with magnetic materials.

  18. A Macroscopic Realization of the Weak Interaction

    NASA Technical Reports Server (NTRS)

    Nishimori, Arito

    2003-01-01

    A.J.Leggett suggested in 1977 that a permanent electric dipole moment due to the parity-nonconserving electron-nucleon interaction, even though it is extremely small, could be measured in the superfluid He-3 B because the moment should be proportional to the size of the sample in this system. If this moment is observed, it will be the first example of a macroscopic realization of the weak interaction. In our planned experiments, a high electric field of up to 6 kV/cm is applied between two parallel electrodes in the He-3 sample. We expect to observe the NMR frequency of the lowest-lying spin-wave mode trapped by the liquid crystal-like texture of the B phase rotation axis in our geometry. The interaction of the electric field and the macroscopic permanent electric dipole moment, which is oriented along the rotation axis, will cause a small change in the texture and hence a small increase in the frequency of the spin wave mode. Besides the basic ideas, we present the purpose and the design of our first cell that is under construction.

  19. Macroscopic equations for the adiabatic piston.

    PubMed

    Cencini, Massimo; Palatella, Luigi; Pigolotti, Simone; Vulpiani, Angelo

    2007-11-01

    A simplified version of a classical problem in thermodynamics--the adiabatic piston--is discussed in the framework of kinetic theory. We consider the limit of gases whose relaxation time is extremely fast so that the gases contained in the left and right chambers of the piston are always in equilibrium (that is, the molecules are uniformly distributed and their velocities obey the Maxwell-Boltzmann distribution) after any collision with the piston. Then by using kinetic theory we derive the collision statistics, from which we obtain a set of ordinary differential equations for the evolution of the macroscopic observables (namely, the piston average velocity and position, the velocity variance, and the temperatures of the two compartments). The dynamics of these equations is compared with simulations of an ideal gas and a microscopic model of a gas devised to verify the assumptions used in the derivation. We show that the equations predict an evolution for the macroscopic variables that catches the basic features of the problem. The results here presented recover those derived, using a different approach, by Gruber, Pache, and Lesne [J. Stat. Phys. 108, 669 (2002); Gruber, Pache, and Lesne,J. Stat. Phys.112, 1177 (2003)].

  20. Measurement contextuality is implied by macroscopic realism

    SciTech Connect

    Chen Zeqian; Montina, A.

    2011-04-15

    Ontological theories of quantum mechanics provide a realistic description of single systems by means of well-defined quantities conditioning the measurement outcomes. In order to be complete, they should also fulfill the minimal condition of macroscopic realism. Under the assumption of outcome determinism and for Hilbert space dimension greater than 2, they were all proved to be contextual for projective measurements. In recent years a generalized concept of noncontextuality was introduced that applies also to the case of outcome indeterminism and unsharp measurements. It was pointed out that the Beltrametti-Bugajski model is an example of measurement noncontextual indeterminist theory. Here we provide a simple proof that this model is the only one with such a feature for projective measurements and Hilbert space dimension greater than 2. In other words, there is no extension of quantum theory providing more accurate predictions of outcomes and simultaneously preserving the minimal labeling of events through projective operators. As a corollary, noncontextuality for projective measurements implies noncontextuality for unsharp measurements. By noting that the condition of macroscopic realism requires an extension of quantum theory, unless a breaking of unitarity is invoked, we arrive at the conclusion that the only way to solve the measurement problem in the framework of an ontological theory is by relaxing the hypothesis of measurement noncontextuality in its generalized sense.

  1. Effect of CeO2 on Cyclic Hot-Corrosion Behavior of Detonation-Gun Sprayed Cr3C2-NiCr Coatings on Ni-Based Superalloy

    NASA Astrophysics Data System (ADS)

    Saladi, Sekar; Menghani, Jyoti; Prakash, Satya

    2015-03-01

    The hot-corrosion behavior of detonation-gun sprayed Cr3C2-NiCr coatings with and without 0.4 wt.% CeO2 additive on Ni-based superalloy inconel-718 is comparatively discussed in the present study. Hot-corrosion studies were carried out at 900 °C for 100 cycles in Na2SO4-60%V2O5 molten salt environment under cyclic heating and cooling conditions on bare and coated superalloys. The thermo-gravimetric technique was used to establish kinetics of hot-corrosion. XRD, FESEM/EDAX, and EDX mapping techniques were used to analyze the corrosion products of bare and coated samples. The results indicate that Cr3C2-NiCr-CeO2-coated superalloy showed better hot-corrosion resistance as compared to bare and Cr3C2-NiCr-coated superalloys. The addition of CeO2 has improved micro-hardness, porosity, and surface roughness values of Cr3C2-NiCr-CeO2 coating. The overall weight gain and parabolic rate constant of Cr3C2-NiCr-CeO2-coated superalloy were found to be lowest in the present study signifying that the addition of CeO2 in Cr3C2-NiCr powder has contributed to the development of adherent and dense oxide scale on the coating at elevated temperature.

  2. Flame spraying of polymers

    SciTech Connect

    Varacalle, D.J. Jr.; Zeek, D.P.; Couch, K.W.; Benson, D.M.; Kirk, S.M.

    1997-08-01

    Statistical design-of-experiment studies of the thermal spraying of polymer powders are presented. Studies of the subsonic combustion (i.e., Flame) process were conducted in order to determine the quality and economics of polyester and urethane coatings. Thermally sprayed polymer coatings are of interest to several industries for anticorrosion applications, including the chemical, automotive, and aircraft industries. In this study, the coating design has been optimized for a site-specific application using Taguchi-type fractional-factorial experiments. Optimized coating designs are presented for the two powder systems. A substantial range of thermal processing conditions and their effect on the resultant polymer coatings is presented. The coatings were characterized by optical metallography, hardness testing, tensile testing, and compositional analysis. Characterization of the coatings yielded the thickness, bond strength, Knoop microhardness, roughness, deposition efficiency, and porosity. Confirmation testing was accomplished to verify the coating designs.

  3. Spray Nozzle Calibrations

    DTIC Science & Technology

    1986-01-01

    1984. The manuscript was submitted for publication on October 2, 1985. AEOC-TR-85-eO CONTENTS Page J.O INTRODUCTION 1.1 General 5 1.2...1.1 GENERAL The formation of ice on aircraft surfaces occurs during flight through clouds of supercooled water droplets. Ice accretion on these... wind tunnel. Both the LWC and mean effective droplet size are set and maintained through variations in the water and air supply pressures of the spray

  4. Spray combustion stability project

    NASA Technical Reports Server (NTRS)

    Jeng, San-Mou; Litchford, Ron J.

    1990-01-01

    This report summarizes research activity on the Spray Combustion Stability Project, characterizes accomplishments and current status, and discusses projected future work. The purpose is to provide a concise conceptual overview of the research effort so the reader can quickly assimilate the gist of the research results and place them within the context of their potential impact on liquid rocket engine design technology. Therefore, this report does not elaborate on many of the detailed technical aspects of the research program.

  5. Vacuum plasma spray coating

    NASA Technical Reports Server (NTRS)

    Holmes, Richard R.; Mckechnie, Timothy N.

    1989-01-01

    Currently, protective plasma spray coatings are applied to space shuttle main engine turbine blades of high-performance nickel alloys by an air plasma spray process. Originally, a ceramic coating of yttria-stabilized zirconia (ZrO2.12Y2O3) was applied for thermal protection, but was removed because of severe spalling. In vacuum plasma spray coating, plasma coatings of nickel-chromium-aluminum-yttrium (NiCrAlY) are applied in a reduced atmosphere of argon/helium. These enhanced coatings showed no spalling after 40 MSFC burner rig thermal shock cycles between 927 C (1700 F) and -253 C (-423 F), while current coatings spalled during 5 to 25 test cycles. Subsequently, a process was developed for applying a durable thermal barrier coating of ZrO2.8Y2O3 to the turbine blades of first-stage high-pressure fuel turbopumps utilizing the enhanced NiCrAlY bond-coating process. NiCrAlY bond coating is applied first, with ZrO2.8Y2O3 added sequentially in increasing amounts until a thermal barrier coating is obtained. The enchanced thermal barrier coating has successfully passed 40 burner rig thermal shock cycles.

  6. Fundamental studies of spray combustion

    SciTech Connect

    Li, S.C.; Libby, P.A.; Williams, F.A.

    1997-12-31

    Our research on spray combustion involves both experiment and theory and addresses the characteristics of individual droplets and of sprays in a variety of flows: laminar and turbulent, opposed and impinging. Currently our focus concerns water and fuel sprays in two stage laminar flames, i.e., flames arising, for example from a stream of fuel and oxidizer flowing opposite to an air stream carrying a water spray. Our interest in these flames is motivated by the goals of reducing pollutant emissions and extending the range of stable spray combustion. There remains considerable research to be carried out in order to achieve these goals. Thus far our research on the characteristics of sprays in turbulent flows has been limited to nonreacting jets impinging on a plate but this work will be extended to opposed flows with and without a flame. In the following we discuss details of these studies and our plans for future work.

  7. Macromolecular recognition and macroscopic interactions by cyclodextrins.

    PubMed

    Harada, Akira; Takashima, Yoshinori

    2013-10-01

    Herein macromolecular recognition by cyclodextrins (CDs) is summarized. Recognition of macromolecules by CDs is classified as main-chain recognition or side-chain recognition. We found that CDs form inclusion complexes with various polymers with high selectivity. Polyrotaxanes in which many CDs are entrapped in a polymer chain were prepared. Tubular polymers were prepared from the polyrotaxanes. CDs were found to recognize side-chains of polymers selectively. CD host polymers were found to form gels with guest polymers in water. These gels showed self-healing properties. When azobenzene was used as a guest, the gel showed sol-gel transition by photoirradiation. When ferrocene was used, redox-responsive gels were obtained. Macroscopic self-assembly through molecular recognition has been discovered. Photoswitchable gel association and dissociation have been observed.

  8. Making Macroscopic Assemblies of Aligned Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Smalley, Richard E.; Colbert, Daniel T.; Smith, Ken A.; Walters, Deron A.; Casavant, Michael J.; Qin, Xiaochuan; Yakobson, Boris; Hauge, Robert H.; Saini, Rajesh Kumar; Chiung, Wan-Ting; Huffman, Charles B.

    2005-01-01

    A method of aligning and assembling single-wall carbon nanotubes (SWNTs) to fabricate macroscopic structures has been invented. The method entails suspending SWNTs in a fluid, orienting the SWNTs by use of a magnetic and/or electric field, and then removing the aligned SWNTs from suspension in such a way as to assemble them while maintaining the alignment. SWNTs are essentially tubular extensions of fullerene molecules. It is desirable to assemble aligned SWNTs into macroscopic structures because the common alignment of the SWNTs in such a structure makes it possible to exploit, on a macroscopic scale, the unique mechanical, chemical, and electrical properties that individual oriented SWNTs exhibit at the molecular level. Because of their small size and high electrical conductivity, carbon nanotubes, and especially SWNTs, are useful for making electrical connectors in integrated circuits. Carbon nanotubes can be used as antennas at optical frequencies, and as probes in scanning tunneling microscopes, atomic-force microscopes, and the like. Carbon nanotubes can be used with or instead of carbon black in tires. Carbon nanotubes are useful as supports for catalysts. Ropes of SWNTs are metallic and, as such, are potentially useful in some applications in which electrical conductors are needed - for example, they could be used as additives in formulating electrically conductive paints. Finally, macroscopic assemblies of aligned SWNTs can serve as templates for the growth of more and larger structures of the same type. The great variety of tubular fullerene molecules and of the structures that could be formed by assembling them in various ways precludes a complete description of the present method within the limits of this article. It must suffice to present a typical example of the use of one of many possible variants of the method to form a membrane comprising SWNTs aligned substantially parallel to each other in the membrane plane. The apparatus used in this variant

  9. Macroscopically local correlations can violate information causality.

    PubMed

    Cavalcanti, Daniel; Salles, Alejo; Scarani, Valerio

    2010-01-01

    Although quantum mechanics is a very successful theory, its foundations are still a subject of intense debate. One of the main problems is that quantum mechanics is based on abstract mathematical axioms, rather than on physical principles. Quantum information theory has recently provided new ideas from which one could obtain physical axioms constraining the resulting statistics one can obtain in experiments. Information causality (IC) and macroscopic locality (ML) are two principles recently proposed to solve this problem. However, none of them were proven to define the set of correlations one can observe. In this study, we show an extension of IC and study its consequences. It is shown that the two above-mentioned principles are inequivalent: if the correlations allowed by nature were the ones satisfying ML, IC would be violated. This gives more confidence in IC as a physical principle, defining the possible correlation allowed by nature.

  10. Partitioning a macroscopic system into independent subsystems

    NASA Astrophysics Data System (ADS)

    Delle Site, Luigi; Ciccotti, Giovanni; Hartmann, Carsten

    2017-08-01

    We discuss the problem of partitioning a macroscopic system into a collection of independent subsystems. The partitioning of a system into replica-like subsystems is nowadays a subject of major interest in several fields of theoretical and applied physics. The thermodynamic approach currently favoured by practitioners is based on a phenomenological definition of an interface energy associated with the partition, due to a lack of easily computable expressions for a microscopic (i.e. particle-based) interface energy. In this article, we outline a general approach to derive sharp and computable bounds for the interface free energy in terms of microscopic statistical quantities. We discuss potential applications in nanothermodynamics and outline possible future directions.

  11. Macroscopic model of scanning force microscope

    DOEpatents

    Guerra-Vela, Claudio; Zypman, Fredy R.

    2004-10-05

    A macroscopic version of the Scanning Force Microscope is described. It consists of a cantilever under the influence of external forces, which mimic the tip-sample interactions. The use of this piece of equipment is threefold. First, it serves as direct way to understand the parts and functions of the Scanning Force Microscope, and thus it is effectively used as an instructional tool. Second, due to its large size, it allows for simple measurements of applied forces and parameters that define the state of motion of the system. This information, in turn, serves to compare the interaction forces with the reconstructed ones, which cannot be done directly with the standard microscopic set up. Third, it provides a kinematics method to non-destructively measure elastic constants of materials, such as Young's and shear modules, with special application for brittle materials.

  12. Macroscopic Quantum Tunneling in One Dimensional Superconductor

    NASA Astrophysics Data System (ADS)

    Chang, Yongmin

    Macroscopic quantum tunneling (MQT) in a one dimensional superconductor is discussed based on the microscopic model near the critical temperature. By means of a functional integral approach, a formula for the total decay rate, which is the sum of the thermal activation and quantum mechanical tunneling rate, is derived. The Bounce solution in the imaginary time formalism gives rise to the exponent in the tunneling rate. From the study of fluctuations from the bounce path, the pre-exponential factor has been evaluated. The theory for the tunneling rate is consistent with experimental results for temperatures at which the thermal activation theory fails. As the temperature approaches to the critical temperature, thermal activation over a free energy barrier which separates metastable states is dominant and the theory shows good agreement with experiment over the whole temperature region.

  13. Variability of macroscopic dimensions of Moso bamboo.

    PubMed

    Cui, Le; Peng, Wanxi; Sun, Zhengjun; Sun, Zhengjun; Sun, Zhengjun; Lu, Huangfei; Chen, Guoning

    2015-03-01

    In order to the macroscopic geometry distributions of vascular bundles in Moso bamboo tubes. The circumference of bamboo tubes was measured, used a simple quadratic diameter formula to analyze the differences between the tubes in bamboo culm, and the arrangement of vascular bundles was investigated by cross sectional images of bamboo tubes. The results shown that the vascular bundles were differently distributed in a bamboo tube. In the outer layer, the vascular bundles had a variety of shapes, and were aligned parallel to each other. In the inner layers, the vascular bundles weren't aligned but uniform in shape. It was concluded that the vascular bundle sections arranged in parallel should be separated from the non-parallel sections for the maximum bamboo utilization.

  14. A review of macroscopic thrombus modeling methods.

    PubMed

    Cito, Salvatore; Mazzeo, Marco Domenico; Badimon, Lina

    2013-02-01

    Hemodynamics applied to mechanobiology offers powerful means to predict thrombosis, and to understand the kinetics of thrombus formation on areas of vascular damage in blood flowing through the human circulatory system. Specifically, the advances in computational processing and the progress in modeling complex biological processes with spatio-temporal multi-scale methods have the potential to shift the way in which cardiovascular diseases are diagnosed and treated. This article systematically surveys the state of the art of macroscopic computational fluid dynamics (CFD) Computational fluid dynamics techniques for modeling thrombus formation, highlighting their strengths and weaknesses. In particular, a comprehensive and systematic revision of the hemodynamics models and methods is given, and the strengths and weaknesses of those employed for studying thrombus formation are highlighted. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Macroscopic quantum entanglement in modulated optomechanics

    NASA Astrophysics Data System (ADS)

    Wang, Mei; Lü, Xin-You; Wang, Ying-Dan; You, J. Q.; Wu, Ying

    2016-11-01

    Quantum entanglement in mechanical systems is not only a key signature of macroscopic quantum effects but has wide applications in quantum technologies. Here we propose an effective approach for creating strong steady-state entanglement between two directly coupled mechanical oscillators (or a mechanical oscillator and a microwave resonator) in a modulated optomechanical system. The entanglement is achieved by combining the processes of a cavity cooling and the two-mode parametric interaction, which can surpass the bound on the maximal stationary entanglement from the two-mode parametric interaction. In principle, our proposal allows one to cool the system from an initial thermal state to an entangled state with high purity by a monochromatic driving laser. Also, the obtained entangled state can be used to implement the continuous-variable teleportation with high fidelity. Moreover, our proposal is robust against the thermal fluctuations of the mechanical modes under the condition of strong optical pumping.

  16. Black holes and quantumness on macroscopic scales

    NASA Astrophysics Data System (ADS)

    Flassig, Daniel; Pritzel, Alexander; Wintergerst, Nico

    2013-04-01

    It has recently been suggested that black holes may be described as condensates of weakly interacting gravitons at a critical point, exhibiting strong quantum effects. In this paper, we study a model system of attractive bosons in one spatial dimension which is known to undergo a quantum phase transition. We demonstrate explicitly that indeed quantum effects are important at the critical point, even if the number of particles is macroscopic. Most prominently, we evaluate the entropy of entanglement between different momentum modes and observe it to become maximal at the critical point. Furthermore, we explicitly see that the leading entanglement is between long-wavelength modes and is hence a feature independent of ultraviolet physics. If applicable to black holes, our findings substantiate the conjectured breakdown of semiclassical physics even for large black holes. This can resolve long-standing mysteries, such as the information paradox and the no-hair theorem.

  17. Macroscopic balance model for wave rotors

    NASA Technical Reports Server (NTRS)

    Welch, Gerard E.

    1996-01-01

    A mathematical model for multi-port wave rotors is described. The wave processes that effect energy exchange within the rotor passage are modeled using one-dimensional gas dynamics. Macroscopic mass and energy balances relate volume-averaged thermodynamic properties in the rotor passage control volume to the mass, momentum, and energy fluxes at the ports. Loss models account for entropy production in boundary layers and in separating flows caused by blade-blockage, incidence, and gradual opening and closing of rotor passages. The mathematical model provides a basis for predicting design-point wave rotor performance, port timing, and machine size. Model predictions are evaluated through comparisons with CFD calculations and three-port wave rotor experimental data. A four-port wave rotor design example is provided to demonstrate model applicability. The modeling approach is amenable to wave rotor optimization studies and rapid assessment of the trade-offs associated with integrating wave rotors into gas turbine engine systems.

  18. Characterization of Macroscopic Ordering in Exciton Rings

    NASA Astrophysics Data System (ADS)

    Yang, Sen; Levitov, L. S.; Simons, B. D.; Gossard, A. C.

    2005-03-01

    Recently observed complex PL patterns in 2D QW structures exhibit the inner [1,3] and the outer [1-4] exciton rings, localized bright spots [1,3], and the macroscopically ordered exciton state (MOES) [1,3]. The latter appears at the outer ring via its fragmentation into a periodic array of aggregates. While the gross features have been explained within classical framework, attributing the inner rings to nonradiative exciton transport and cooling [1], and the outermost rings and the bright spots to macroscopic charge separation [3,4], the origin of the MOES remains unidentified [5]. Here, for the first time, we report experiments demonstrating the exciton energy modulation over the MOES as well as the phase diagram of MOES in exciton density and temperature coordinates. The experiments shed new light on the dynamical origin of MOES. Besides, we present the studies of dynamical processes within MOES including the observation of aggregate instabilities and bifurcations that point to the spontaneous character of the instability.[1] L.V. Butov, A.C. Gossard, D.S. Chemla, Nature 418, 751 (2002). [2] D. Snoke, S. Denev, Y. Liu, L. Pfeiffer, K. West, Nature 418, 754 (2002). [3] L.V. Butov, L.S. Levitov, A.V. Mintsev, B.D. Simons, A.C. Gossard, D.S. Chemla PRL 92, 117404 (2004). [4] R. Rapaport, G. Chen, D. Snoke, S.H. Simon, L. Pfeiffer, K. West, Y. Liu, S. Denev PRL 92, 117405 (2004). [5] L.S. Levitov, B.D. Simons, L.V. Butov, cond-mat/0403377.

  19. Macroscopic model for solvated ion dynamics

    NASA Astrophysics Data System (ADS)

    Chen, J.-H.; Adelman, S. A.

    1980-02-01

    A macroscopic treatment of solvated ion dynamics is developed and applied to calculate the limiting (zero concentration) conductance of cations in several aprotic solvents. The theory is based on a coupled set of electrostatic and hydrodynamic equations for the density, flow, and polarization fields induced in the polar solvent by a moving ion. These equations, which are derived by the Mori projection technique, include crucial local solvent structure (ion solvation) effects through solvent compressibility, and local constitutive parameters. If solvent structure is suppressed, the equations reduce to those derived previously by Onsager and Hubbard [J. B. Hubbard and L. Onsager, J. Chem. Phys. 67, 4850 (1977)]. The macroscopic equations are approximately decoupled into electrostatic and hydrodynamic parts. The decoupled equations are solved assuming a step density, viscosity, and dielectric constant model for the local solvent structure and dynamics. This yields analytic expressions for the viscous, ζV, and dielectric ζD, contributions to the ion friction coefficient. These expressions generalize, respectively, the Stokes and Zwanzig results for the (slip) viscous and dielectric friction so as to account for ion solvation effects. The friction coefficients involve a desolvation function Δ which depends on the local structure (density) and dynamics of the solvent. The drag coefficient results reduce in form to those of Zwanzig (within a flow gradient correction factor of 2/3) and Stokes for both weak (Δ→1) and strong (Δ→0) ion-solvent interaction. For Δ→1 the true ionic radius Ri appears in the drag formulas while for Δ→0 a renormalized solvated ion radius σ=Ri+2Rs (where Rs=solvent molecule radius) appears. The theory is fit to experimental cation conductances in pyridine, acetone, and acetonitrile by representing Δ by a two parameter switching function. Agreement between the model and experiment is satisfactory for all three solvents. Moreover

  20. Determining the Macroscopic Properties of Relativistic Jets

    NASA Astrophysics Data System (ADS)

    Hardee, P. E.

    2004-08-01

    The resolved relativistic jets contain structures whose observed proper motions are typically assumed to indicate the jet flow speed. In addition to structures moving with the flow, various normal mode structures such as pinching or helical and elliptical twisting can be produced by ejection events or twisting perturbations to the jet flow. The normal mode structures associated with relativistic jets, as revealed by numerical simulation, theoretical calculation, and suggested by observation, move more slowly than the jet speed. The pattern speed is related to the jet speed by the sound speed in the jet and in the surrounding medium. In the event that normal mode structures are observed, and where proper motions of pattern and flow speed are available or can be estimated, it is possible to determine the sound speed in the jet and surrounding medium. Where spatial development of normal mode structures is observed, it is possible to make inferences as to the heating rate/macroscopic viscosity of the jet fluid. Ultimately it may prove possible to separate the microscopic energization of the synchrotron radiating particles from the macroscopic heating of the jet fluid. Here I present the relevant properties of useful normal mode structures and illustrate the use of this technique. Various aspects of the work presented here have involved collaboration with I. Agudo (Max-Planck, Bonn), M.A. Aloy (Max-Planck, Garching), J. Eilek (NM Tech), J.L. Gómez (U. Valencia), P. Hughes (U. Michigan), A. Lobanov (Max-Planck, Bonn), J.M. Martí (U. Valencia), & C. Walker (NRAO).

  1. Closed loop spray cooling apparatus

    NASA Technical Reports Server (NTRS)

    Alger, D. L.; Schwab, W. B.; Furman, E. R. (Inventor)

    1979-01-01

    A closed loop apparatus for jet spraying coolant against the back of a radiation target is described. The coolant is circulated through a closed loop with a bubble of inert gas being maintained around the spray. Mesh material is disposed between the bubble and the surface of the liquid coolant which is below the bubble at a predetermined level. In a second arrangement no inert gas is used, the bubble consists of vapor produced when the coolant is sprayed against the target.

  2. Photomicrographic Studies of Fuel Sprays

    NASA Technical Reports Server (NTRS)

    Lee, Dana W; Spencer, Robert C

    1934-01-01

    A large number of photomicrographs of fuel sprays were taken for the purpose of studying the spray structure and the process of spray formation. They were taken at magnifying powers of 2.5, 3.25, and 10, using a spark discharge of very short duration for illumination. Several types and sizes of nozzles were investigated, different liquids were used, and a wide range of injection pressures was employed. The sprays were photographed as they were injected into a glass-walled chamber in which the air density was varied from 14 atmospheres to 0.0013 atmosphere.

  3. Vacuum Plasma Spraying Replaces Electrodeposition

    NASA Technical Reports Server (NTRS)

    Holmes, Richard R.; Power, Chris; Burns, David H.; Daniel, Ron; Mckechnie, Timothy N.

    1992-01-01

    Vacuum plasma spraying used to fabricate large parts with complicated contours and inner structures, without uninspectable welds. Reduces time, and expense of fabrication. Wall of combustion chamber built up inside of outer nickel-alloy jacket by plasma spraying. Particles of metal sprayed partially melted in plasma gun and thrown at supersonic speed toward deposition surface. Vacuum plasma-spray produces stronger bond between the grooves and covering layer completing channels and wall of combustion chamber. In tests, bond withstood pressure of 20 kpsi, three times allowable limit by old method.

  4. Macroscopic entanglement in many-particle quantum states

    NASA Astrophysics Data System (ADS)

    Tichy, Malte C.; Park, Chae-Yeun; Kang, Minsu; Jeong, Hyunseok; Mølmer, Klaus

    2016-04-01

    We elucidate the relationship between Schrödinger-cat-like macroscopicity and geometric entanglement and argue that these quantities are not interchangeable. While both properties are lost due to decoherence, we show that macroscopicity is rare in uniform and in so-called random physical ensembles of pure quantum states, despite possibly large geometric entanglement. In contrast, permutation-symmetric pure states feature rather low geometric entanglement and strong and robust macroscopicity.

  5. Simulation of Motion, Heating, and Breakup of Molten Metal Droplets in the Plasma Jet at Plasma-Arc Spraying

    NASA Astrophysics Data System (ADS)

    Kharlamov, M. Yu.; Krivtsun, I. V.; Korzhyk, V. N.; Ryabovolyk, Y. V.; Demyanov, O. I.

    2015-04-01

    The mathematical model for the process of plasma-arc wire spraying is proposed, which describes behavior of molten metal droplets in the plasma jet, allowing for the processes of their deformation and gas-dynamic breakup. Numerical analysis of the processes of motion, heating, and breakup of molten metal droplets, detached from the sprayed wire at plasma-arc spraying of coatings, was performed. It is shown that during molten droplets movement in the plasma jet their multiple breakup takes place, leading to formation of sprayed particles with dimensions much smaller than dimensions of initial droplets, detached from the sprayed wire tip.

  6. Selective and conventional house-spraying of DDT and bendiocarb against Anopheles pseudopunctipennis in southern Mexico.

    PubMed

    Casas, M; Torres, J L; Bown, D N; Rodríguez, M H; Arredondo-Jiménez, J I

    1998-12-01

    Indoor feeding behaviors and mortalities of Anopheles pseudopunctipennis females were evaluated following contact with selective (bands covering mosquitoes' preferred resting areas) and full applications of DDT and bendiocarb on indoor sprayable surfaces. The DDT residues provoked strong avoidance behavior. To a lesser degree, mosquitoes were also repelled by bendiocarb-sprayed surfaces. Because of strong irritancy/repellency, unfed mosquitoes were driven outdoors in proportionally higher numbers. The resting time on selectively or fully DDT-sprayed huts was greatly reduced in comparison to bendiocarb-sprayed huts. Although unfed mosquitoes tended to rest on non-DDT-sprayed surfaces in the selectively treated hut, the man-biting rate was similar with both types of treatments. Unfed mosquitoes were repelled less from selectively bendiocarb-treated surfaces. Similar reductions in postfed resting times were observed on all surfaces suggesting that once fed, mosquitoes rested on sprayed surfaces for shorter intervals of time. Engorged mosquitoes had normal resting behavior (pre- and postspray) within the range of preferred resting heights in both DDT- and bendiocarb-sprayed huts, but the proportion of mosquitoes fed in the DDT-treated huts was lower. Selective spraying of walls was as effective as spraying the complete walls with both insecticides, but DDT was more effective in reducing mosquito-human contact. These studies show that by more effectively targeting vector behavior, a cost-effective alternative to traditional control techniques can be achieved.

  7. Stress rupture and creep behavior of a low pressure plasma-sprayed NiCoCrAlY coating alloy in air and vacuum

    NASA Technical Reports Server (NTRS)

    Hebsur, M. G.; Miner, R. V.

    1987-01-01

    The creep behavior of a NiCoCrAlY coating alloy in air and vacuum at 660 and 850 C is studied. The microstructure of the coating alloy is described. Analysis of the creep curves reveal that the secondary creep rates, the transition from secondary to tertiary creep, and the strain-to-failure are affected by the environment, preexposure, stress, and temperature. It is observed that the rupture lives of the NiCoCrAlY alloy at 660 and 850 C are greater in air than in vacuum. Several mechanisms that may explain the lack of crack growth from surface-connected pores during tests in air are proposed.

  8. Stress rupture and creep behavior of a low pressure plasma-sprayed NiCoCrAlY coating alloy in air and vacuum

    NASA Technical Reports Server (NTRS)

    Hebsur, M. G.; Miner, R. V.

    1987-01-01

    The creep behavior of a NiCoCrAlY coating alloy in air and vacuum at 660 and 850 C is studied. The microstructure of the coating alloy is described. Analysis of the creep curves reveal that the secondary creep rates, the transition from secondary to tertiary creep, and the strain-to-failure are affected by the environment, preexposure, stress, and temperature. It is observed that the rupture lives of the NiCoCrAlY alloy at 660 and 850 C are greater in air than in vacuum. Several mechanisms that may explain the lack of crack growth from surface-connected pores during tests in air are proposed.

  9. Macroscopic acousto-mechanical analogy of a microbubble.

    PubMed

    Chaline, Jennifer; Jiménez, Noé; Mehrem, Ahmed; Bouakaz, Ayache; Dos Santos, Serge; Sánchez-Morcillo, Víctor J

    2015-12-01

    Microbubbles, either in the form of free gas bubbles surrounded by a fluid or encapsulated bubbles used currently as contrast agents for medical echography, exhibit complex dynamics under specific acoustic excitations. Nonetheless, considering their micron size and the complexity of their interaction phenomenon with ultrasound waves, expensive and complex experiments and/or simulations are required for their analysis. The behavior of a microbubble along its equator can be linked to a system of coupled oscillators. In this study, the oscillatory behavior of a microbubble has been investigated through an acousto-mechanical analogy based on a ring-shaped chain of coupled pendula. Observation of parametric vibration modes of the pendula ring excited at frequencies between 1 and 5 Hz is presented. Simulations have been carried out and show mode mixing phenomena. The relevance of the analogy between a microbubble and the macroscopic acousto-mechanical setup is discussed and suggested as an alternative way to investigate the complexity of microbubble dynamics.

  10. Atomistic study of macroscopic analogs to short-chain molecules.

    PubMed

    Welch, Kyle J; Kilmer, Clayton S G; Corwin, Eric I

    2015-02-01

    We use a bath of chaotic surface waves in water to mechanically and macroscopically mimic the thermal behavior of a short articulated chain with only nearest-neighbor interactions. The chaotic waves provide isotropic and random agitation to which a temperature can be ascribed, allowing the chain to passively explore its degrees of freedom in analogy to thermal motion. We track the chain in real time and infer end-to-end potentials using Boltzmann statistics. We extrapolate our results, by using Monte Carlo simulations of self-avoiding polymers, to lengths not accessible in our system. In the long-chain limit we demonstrate universal scaling of the statistical parameters of all chains in agreement with well-known predictions for self-avoiding walks. However, we find that the behavior of chains below a characteristic length scale fundamentally differs. We find that short chains have much greater compressional stiffness than would be expected. However, chains rapidly soften as length increases to meet with expected scalings.

  11. Macroscopic strain controlled ion current in an elastomeric microchannel

    SciTech Connect

    Kuo, Chin-Chang; Nguyen, Du; Buchsbaum, Steven; Innes, Laura; Dennin, Michael; Li, Yongxue; Esser-Kahn, Aaron P.; Valdevit, Lorenzo; Sun, Lizhi; Siwy, Zuzanna

    2015-05-07

    We report on the fabrication of an ultra-high aspect ratio ionically conductive single microchannel with tunable diameter from ≈ 20 μm to fully closed. The 4 mm-long channel is fabricated in a Polydimethylsiloxane (PDMS) mold and its cross-sectional area is controlled by applying macroscopic compressive strain to the mold in a direction perpendicular to the channel length. We investigated the ionic conduction properties of the channel. For a wide range of compressive strain up to ≈ 0.27, the strain dependence of the resistance is monotonic and fully reversible. For strain > 0.27, ionic conduction suddenly shuts off and the system becomes hysteretic (whereby a finite strain reduction is required to reopen the channel). Upon unloading, the original behavior is retrieved. This reversible behavior is observed over 200 compression cycles. The cross-sectional area of the channel can be inferred from the ion current measurement, as confirmed by a Nano-Computed Tomography investigation. We show that the cross-sectional area decreases monotonically with the applied compressive strain in the reversible range, in qualitative agreement with linear elasticity theory. We find that the shut-off strain is affected by the spatial extent of the applied strain, which provides additional tunability. Our tunable channel is well-suited for multiple applications in micro/nano-fluidic devices.

  12. Characterization of Modified Tapioca Starch Solutions and Their Sprays for High Temperature Coating Applications

    PubMed Central

    Naz, M. Y.; Sulaiman, S. A.; Ariwahjoedi, B.; Shaari, Ku Zilati Ku

    2014-01-01

    The objective of the research was to understand and improve the unusual physical and atomization properties of the complexes/adhesives derived from the tapioca starch by addition of borate and urea. The characterization of physical properties of the synthesized adhesives was carried out by determining the effect of temperature, shear rate, and mass concentration of thickener/stabilizer on the complex viscosity, density, and surface tension. In later stage, phenomenological analyses of spray jet breakup of heated complexes were performed in still air. Using a high speed digital camera, the jet breakup dynamics were visualized as a function of the system input parameters. The further analysis of the grabbed images confirmed the strong influence of the input processing parameters on full cone spray patternation. It was also predicted that the heated starch adhesive solutions generate a dispersed spray pattern by utilizing the partial evaporation of the spraying medium. Below 40°C of heating temperature, the radial spray cone width and angle did not vary significantly with increasing Reynolds and Weber numbers at early injection phases leading to increased macroscopic spray propagation. The discharge coefficient, mean flow rate, and mean flow velocity were significantly influenced by the load pressure but less affected by the temperature. PMID:24592165

  13. Characterization of modified tapioca starch solutions and their sprays for high temperature coating applications.

    PubMed

    Naz, M Y; Sulaiman, S A; Ariwahjoedi, B; Shaari, Ku Zilati Ku

    2014-01-01

    The objective of the research was to understand and improve the unusual physical and atomization properties of the complexes/adhesives derived from the tapioca starch by addition of borate and urea. The characterization of physical properties of the synthesized adhesives was carried out by determining the effect of temperature, shear rate, and mass concentration of thickener/stabilizer on the complex viscosity, density, and surface tension. In later stage, phenomenological analyses of spray jet breakup of heated complexes were performed in still air. Using a high speed digital camera, the jet breakup dynamics were visualized as a function of the system input parameters. The further analysis of the grabbed images confirmed the strong influence of the input processing parameters on full cone spray patternation. It was also predicted that the heated starch adhesive solutions generate a dispersed spray pattern by utilizing the partial evaporation of the spraying medium. Below 40°C of heating temperature, the radial spray cone width and angle did not vary significantly with increasing Reynolds and Weber numbers at early injection phases leading to increased macroscopic spray propagation. The discharge coefficient, mean flow rate, and mean flow velocity were significantly influenced by the load pressure but less affected by the temperature.

  14. Spray algorithm without interface construction

    NASA Astrophysics Data System (ADS)

    Al-Kadhem Majhool, Ahmed Abed; Watkins, A. P.

    2012-05-01

    This research is aimed to create a new and robust family of convective schemes to capture the interface between the dispersed and the carrier phases in a spray without the need to build up the interface boundary. The selection of the Weighted Average Flux (WAF) scheme is due to this scheme being designed to deal with random flux scheme which is second-order accurate in space and time. The convective flux in each cell face utilizes the WAF scheme blended with Switching Technique for Advection and Capturing of Surfaces (STACS) scheme for high resolution flux limiters. In the next step, the high resolution scheme is blended with the WAF scheme to provide the sharpness and boundedness of the interface by using switching strategy. In this work, the Eulerian-Eulerian framework of non-reactive turbulent spray is set in terms of theoretical proposed methodology namely spray moments of drop size distribution, presented by Beck and Watkins [1]. The computational spray model avoids the need to segregate the local droplet number distribution into parcels of identical droplets. The proposed scheme is tested on capturing the spray edges in modelling hollow cone sprays without need to reconstruct two-phase interface. A test is made on simple comparison between TVD scheme and WAF scheme using the same flux limiter on convective flow hollow cone spray. Results show the WAF scheme gives a better prediction than TVD scheme. The only way to check the accuracy of the presented models is by evaluating the spray sheet thickness.

  15. A New Way to Spray

    NASA Technical Reports Server (NTRS)

    2000-01-01

    A NASA SBIR contract provided the funding for a new nozzle shape to be used in plasma spray techniques. The new design, a bell shape, reduces overspray. The result is a significant decrease in the cost of plasma spraying and a higher quality, more pure coating.

  16. Composition versus friction and wear behavior of plasma sprayed WC-(W,Cr)2C-Ni/Ag/BaF2-CaF2 self-lubricating composite coatings for use up to 600 °C

    NASA Astrophysics Data System (ADS)

    Chen, Jianmin; Hou, Guoliang; Chen, Jie; An, Yulong; Zhou, Huidi; Zhao, Xiaoqin; Yang, Jie

    2012-11-01

    This paper reports the composition optimization of self-lubricating composite coatings containing WC-(W,Cr)2C-Ni, silver and fluoride eutectics. Various ingredients obtained by powder blending were studied to determine their optimum content in as-prepared composite coatings. An atmospheric plasma spraying (APS) system was used to deposit promising WC-(W,Cr)2C-Ni/Ag/BaF2-CaF2 self-lubricating composite coatings. The friction and wear behavior of the composite coatings sliding against Si3N4 ball was investigated from room temperature to 600 °C. Results show that silver and fluoride eutectics can effectively reduce the friction coefficient of the coatings and the wear volume loss of counterpart balls over the whole temperature range. Thanks to the highest hardness, WC-(W,Cr)2C-Ni coating without silver and fluoride eutectics has the lowest wear rate at room temperature and 600 °C. However, it has a high friction coefficient and a very high wear rate at 200 and 400 °C, due to severe adhesion wear and fatigue wear thereat. Fortunately, introducing appropriate amount of silver and fluoride eutectics contributes to effectively reduce the wear rate of the composite coatings at 200 and 400 °C. The optimized composite coating consists of 70 wt.% WC-(W,Cr)2C-Ni, 15 wt.% Ag and 15 wt.% BaF2/CaF2, and it has excellent friction and wear performance over a wide range of temperature.

  17. Investigation of dissipative forces near macroscopic media

    SciTech Connect

    Becker, R.S.

    1982-12-01

    The interaction of classical charged particles with the fields they induce in macroscopic dielectric media is investigated. For 10- to 1000-eV electrons, the angular perturbation of the trajectory by the image potential for surface impact parameters of 50 to 100 A is shown to be of the order of 0.001 rads over a distance of 100 A. The energy loss incurred by low-energy particles due to collective excitations such as surface plasmons is shown to be observable with a transition probability of 0.01 to 0.001 (Becker, et al., 1981b). The dispersion of real surface plasmon modes in planar and cylindrical geometries is discussed and is derived for pinhole geometry described in terms of a single-sheeted hyperboloid of revolution. An experimental apparatus for the measurement of collective losses for medium-energy electrons translating close to a dielectric surface is described and discussed. Data showing such losses at electron energies of 500 to 900 eV in silver foils containing many small apertures are presented and shown to be in good agreement with classical stopping power calculations and quantum mechanical calculations carried out in the low-velocity limit. The data and calculations are compared and contrasted with earlier transmission and reflection measurements, and the course of further investigation is discussed.

  18. Electron shading on a macroscopic scale

    NASA Astrophysics Data System (ADS)

    Madziwa, Tsitsi G.; Chen, Francis F.

    2000-10-01

    Damage to thin gate insulators during plasma processing is thought to be caused by the electron shading effect, in which a negative charge on the photoresist prevents electrons from reaching the bottoms of trenches and vias. The resulting positive charge impinging on the oxide layer creates megavolt potentials across it. Though this hypothetical effect has been modeled extensively in computer simulations, it has not been seen in detail in experiment. To test the theory on a macroscopic scale, we have devised an RF discharge at low pressure and low density, such that both the mean free path and the Debye length are larger than the feature sizes, as in actual microcircuits. Circular vias of order 1 mm in diam are drilled in an insulating plate exposed to the plasma, and the current and potential at various depths are measured with charge collectors. The potential distribution in each hole is calculated with a Poisson solver, and the ion trajectories are found numerically, giving the expected I - V characteristics of the collector to be compared with measurements. Of particular interest is the variation of the charging currents during the RF cycle.

  19. Macroscopic superpositions and gravimetry with quantum magnetomechanics

    NASA Astrophysics Data System (ADS)

    Johnsson, Mattias T.; Brennen, Gavin K.; Twamley, Jason

    2016-11-01

    Precision measurements of gravity can provide tests of fundamental physics and are of broad practical interest for metrology. We propose a scheme for absolute gravimetry using a quantum magnetomechanical system consisting of a magnetically trapped superconducting resonator whose motion is controlled and measured by a nearby RF-SQUID or flux qubit. By driving the mechanical massive resonator to be in a macroscopic superposition of two different heights our we predict that our interferometry protocol could, subject to systematic errors, achieve a gravimetric sensitivity of Δg/g ~ 2.2 × 10-10 Hz-1/2, with a spatial resolution of a few nanometres. This sensitivity and spatial resolution exceeds the precision of current state of the art atom-interferometric and corner-cube gravimeters by more than an order of magnitude, and unlike classical superconducting interferometers produces an absolute rather than relative measurement of gravity. In addition, our scheme takes measurements at ~10 kHz, a region where the ambient vibrational noise spectrum is heavily suppressed compared the ~10 Hz region relevant for current cold atom gravimeters.

  20. Macroscopic car condensation in a parking garage.

    PubMed

    Ha, Meesoon; Den Nijs, Marcel

    2002-09-01

    An asymmetric exclusion process type process, where cars move forward along a closed road that starts and terminates at a parking garage, displays dynamic phase transitions into two types of condensate phases where the garage becomes macroscopically occupied. The total car density rho(o) and the exit probability alpha from the garage are the two control parameters. At the transition, the number of parked cars N(p) diverges in both cases, with the length of the road N(s), as N(p) approximately N(y(p))(s) with y(p)=1/2. Towards the transition, the number of parked cars vanishes as N(p) approximately epsilon(beta) with beta=1, epsilon=/alpha-alpha(*)/ or epsilon=|rho(*)(o)-rho(o)/ being the distance from the transition. The transition into the normal phase represents also the onset of transmission of information through the garage. This gives rise to unusual parked car autocorrelations and car density profiles near the garage, which depend strongly on the group velocity of the fluctuations along the road.

  1. Macroscopic liquid-state molecular hydrodynamics

    PubMed Central

    Keanini, R. G.; Tkacik, Peter T.; Fleischhauer, Eric; Shahinian, Hossein; Sholar, Jodie; Azimi, Farzad; Mullany, Brid

    2017-01-01

    Experimental evidence and theoretical modeling suggest that piles of confined, high-restitution grains, subject to low-amplitude vibration, can serve as experimentally-accessible analogs for studying a range of liquid-state molecular hydrodynamic processes. Experiments expose single-grain and multiple-grain, collective dynamic features that mimic those either observed or predicted in molecular-scale, liquid state systems, including: (i) near-collision-time-scale hydrodynamic organization of single-molecule dynamics, (ii) nonequilibrium, long-time-scale excitation of collective/hydrodynamic modes, and (iii) long-time-scale emergence of continuum, viscous flow. In order to connect directly observable macroscale granular dynamics to inaccessible and/or indirectly measured molecular hydrodynamic processes, we recast traditional microscale equilibrium and nonequilibrium statistical mechanics for dense, interacting microscale systems into self-consistent, macroscale form. The proposed macroscopic models, which appear to be new with respect to granular physics, and which differ significantly from traditional kinetic-theory-based, macroscale statistical mechanics models, are used to rigorously derive the continuum equations governing viscous, liquid-like granular flow. The models allow physically-consistent interpretation and prediction of observed equilibrium and non-equilibrium, single-grain, and collective, multiple-grain dynamics. PMID:28139711

  2. Macroscopic superpositions and gravimetry with quantum magnetomechanics

    PubMed Central

    Johnsson, Mattias T.; Brennen, Gavin K.; Twamley, Jason

    2016-01-01

    Precision measurements of gravity can provide tests of fundamental physics and are of broad practical interest for metrology. We propose a scheme for absolute gravimetry using a quantum magnetomechanical system consisting of a magnetically trapped superconducting resonator whose motion is controlled and measured by a nearby RF-SQUID or flux qubit. By driving the mechanical massive resonator to be in a macroscopic superposition of two different heights our we predict that our interferometry protocol could, subject to systematic errors, achieve a gravimetric sensitivity of Δg/g ~ 2.2 × 10−10 Hz−1/2, with a spatial resolution of a few nanometres. This sensitivity and spatial resolution exceeds the precision of current state of the art atom-interferometric and corner-cube gravimeters by more than an order of magnitude, and unlike classical superconducting interferometers produces an absolute rather than relative measurement of gravity. In addition, our scheme takes measurements at ~10 kHz, a region where the ambient vibrational noise spectrum is heavily suppressed compared the ~10 Hz region relevant for current cold atom gravimeters. PMID:27869142

  3. The Proell Effect: A Macroscopic Maxwell's Demon

    NASA Astrophysics Data System (ADS)

    Rauen, Kenneth M.

    2011-12-01

    Maxwell's Demon is a legitimate challenge to the Second Law of Thermodynamics when the "demon" is executed via the Proell effect. Thermal energy transfer according to the Kinetic Theory of Heat and Statistical Mechanics that takes place over distances greater than the mean free path of a gas circumvents the microscopic randomness that leads to macroscopic irreversibility. No information is required to sort the particles as no sorting occurs; the entire volume of gas undergoes the same transition. The Proell effect achieves quasi-spontaneous thermal separation without sorting by the perturbation of a heterogeneous constant volume system with displacement and regeneration. The classical analysis of the constant volume process, such as found in the Stirling Cycle, is incomplete and therefore incorrect. There are extra energy flows that classical thermo does not recognize. When a working fluid is displaced across a regenerator with a temperature gradient in a constant volume system, complimentary compression and expansion work takes place that transfers energy between the regenerator and the bulk gas volumes of the hot and cold sides of the constant volume system. Heat capacity at constant pressure applies instead of heat capacity at constant volume. The resultant increase in calculated, recyclable energy allows the Carnot Limit to be exceeded in certain cycles. Super-Carnot heat engines and heat pumps have been designed and a US patent has been awarded.

  4. Macroscopic hematuria in patients on anticoagulation therapy

    PubMed Central

    Mariyanovski, Valeri; Hadzhiyska, Valeria

    2015-01-01

    Introduction Visible hematuria is not rare in patients on anticoagulant therapy. There is no consensus regarding the diagnostic approach for them; some authors suggest restricted volume of diagnostic procedures because of the low number of urological etiology found. Some antibiotics have been reported to potentiate the effect of oral anticoagulants. Material and methods The study addresses the need for urological assessment of patients on anticoagulation therapy and the possible role of some drugs administrated simultaneously with an oral anticoagulant, for the onset of macroscopic hematuria. Patients hospitalized with hematuria, both with or without anticoagulation therapy, were investigated and followed up. Results The onset of hematuria depends on the monitoring of oral anticoagulation. INR (International Normalized Ratio) value corresponds with the probability of non-urological etiology, where INR>4 carries relatively low risk for urological and malignant etiology. Some antibiotics may influence the anticoagulation effect, so INR value may be elevated and hematuria may occur. Conclusions Anticoagulation therapy should be administrated carefully and individually. The risk of urological etiology of hematuria is lower in patients on oral anticoagulants (especially when INR >4), however, it is not zero. PMID:26568876

  5. Macroscopic liquid-state molecular hydrodynamics

    NASA Astrophysics Data System (ADS)

    Keanini, R. G.; Tkacik, Peter T.; Fleischhauer, Eric; Shahinian, Hossein; Sholar, Jodie; Azimi, Farzad; Mullany, Brid

    2017-01-01

    Experimental evidence and theoretical modeling suggest that piles of confined, high-restitution grains, subject to low-amplitude vibration, can serve as experimentally-accessible analogs for studying a range of liquid-state molecular hydrodynamic processes. Experiments expose single-grain and multiple-grain, collective dynamic features that mimic those either observed or predicted in molecular-scale, liquid state systems, including: (i) near-collision-time-scale hydrodynamic organization of single-molecule dynamics, (ii) nonequilibrium, long-time-scale excitation of collective/hydrodynamic modes, and (iii) long-time-scale emergence of continuum, viscous flow. In order to connect directly observable macroscale granular dynamics to inaccessible and/or indirectly measured molecular hydrodynamic processes, we recast traditional microscale equilibrium and nonequilibrium statistical mechanics for dense, interacting microscale systems into self-consistent, macroscale form. The proposed macroscopic models, which appear to be new with respect to granular physics, and which differ significantly from traditional kinetic-theory-based, macroscale statistical mechanics models, are used to rigorously derive the continuum equations governing viscous, liquid-like granular flow. The models allow physically-consistent interpretation and prediction of observed equilibrium and non-equilibrium, single-grain, and collective, multiple-grain dynamics.

  6. Macroscopic resonant tunnelling through Andreev interferometers

    NASA Astrophysics Data System (ADS)

    Goorden, M. C.; Jacquod, Ph; Weiss, J.

    2008-04-01

    We investigate the conductance through and the spectrum of ballistic chaotic quantum dots attached to two s-wave superconductors, as a function of the phase difference phi between the two order parameters. A combination of analytical techniques—random matrix theory, Nazarov's circuit theory and the trajectory-based semiclassical theory—allows us to explore the quantum-to-classical crossover in detail. When the superconductors are not phase-biased, phi = 0, we recover known results that the spectrum of the quantum dot exhibits an excitation gap, while the conductance across two normal leads carrying NN channels and connected to the dot via tunnel contacts of transparency ΓN is \\propto \\Gamma_{\\mathrm {N}}^2 N_{\\mathrm {N}} . In contrast, when phi = π, the excitation gap closes and the conductance becomes G \\propto \\Gamma_{\\mathrm {N}} N_{\\mathrm {N}} in the universal regime. For \\Gamma_{\\mathrm {N}} \\ll 1 , we observe an order-of-magnitude enhancement of the conductance towards G \\propto N_{\\mathrm {N}} in the short-wavelength limit. We relate this enhancement to resonant tunnelling through a macroscopic number of levels close to the Fermi energy. Our predictions are corroborated by numerical simulations.

  7. Substrate system for spray forming

    DOEpatents

    Chu, Men G.; Chernicoff, William P.

    2002-01-01

    A substrate system for receiving a deposit of sprayed metal droplets including a movable outer substrate on which the sprayed metal droplets are deposited. The substrate system also includes an inner substrate disposed adjacent the outer substrate where the sprayed metal droplets are deposited on the outer substrate. The inner substrate includes zones of differing thermal conductivity to resist substrate layer porosity and to resist formation of large grains and coarse constituent particles in a bulk layer of the metal droplets which have accumulated on the outer substrate. A spray forming apparatus and associated method of spray forming a molten metal to form a metal product using the substrate system of the invention is also provided.

  8. Substrate system for spray forming

    DOEpatents

    Chu, Men G.; Chernicoff, William P.

    2000-01-01

    A substrate system for receiving a deposit of sprayed metal droplets including a movable outer substrate on which the sprayed metal droplets are deposited. The substrate system also includes an inner substrate disposed adjacent the outer substrate where the sprayed metal droplets are deposited on the outer substrate. The inner substrate includes zones of differing thermal conductivity to resist substrate layer porosity and to resist formation of large grains and coarse constituent particles in a bulk layer of the metal droplets which have accumulated on the outer substrate. A spray forming apparatus and associated method of spray forming a molten metal to form a metal product using the substrate system of the invention is also provided.

  9. Macroscopic quantum tunnelling in a current biased Josephson junction

    SciTech Connect

    Martinis, J.M.; Devoret, M.H.; Clarke, J.; Urbina, C.

    1984-11-01

    We discuss in this work an attempt to answer experimentally the question: do macroscopic variables obey quantum mechanics. More precisely, this experiment deals with the question of quantum-mechanical tunnelling of a macroscopic variable, a subject related to the famous Schrodinger's cat problem in the theory of measurement.

  10. Quantum-state preparation and macroscopic entanglement in gravitational-wave detectors

    SciTech Connect

    Mueller-Ebhardt, Helge; Rehbein, Henning; Schnabel, Roman; Danzmann, Karsten; Li Chao; Mino, Yasushi; Chen Yanbei

    2009-10-15

    Long-baseline laser-interferometer gravitational-wave (GW) detectors are operating at a factor of {approx}10 (in amplitude) above the standard quantum limit (SQL) within a broad frequency band (in the sense that {delta}f{approx}f). Such a low-noise budget has already allowed the creation of a controlled 2.7 kg macroscopic oscillator with an effective eigenfrequency of 150 Hz and an occupation number of {approx}200. This result, along with the prospect for further improvements, heralds the possibility of experimentally probing macroscopic quantum mechanics (MQM) - quantum mechanical behavior of objects in the realm of everyday experience - using GW detectors. In this paper, we provide the mathematical foundation for the first step of a MQM experiment: the preparation of a macroscopic test mass into a nearly minimum-Heisenberg-limited Gaussian quantum state, which is possible if the interferometer's classical noise beats the SQL in a broad frequency band. Our formalism, based on Wiener filtering, allows a straightforward conversion from the noise budget of a laser interferometer, in terms of noise spectra, into the strategy for quantum-state preparation and the quality of the prepared state. Using this formalism, we consider how Gaussian entanglement can be built among two macroscopic test masses and the performance of the planned Advanced LIGO interferometers in quantum-state preparation.

  11. Measurements of the Thermal Neutron Macroscopic Absorption Cross Section for Neutron Absorbing Layers

    NASA Astrophysics Data System (ADS)

    Kiyani, Abouzar; Rostam, G. Gh.; Sadat Kiai, S. M.; Bakhsh, Hossin Jahan; Mahdavi, Farzad

    2011-12-01

    Objective of this study is measuring the macroscopic cross section of a neutron absorbing layer for thermal neutrons. For this purpose a neutron source and BF 3 detector have been applied. For measuring macroscopic cross section of thermal neutrons by the Formula, it is necessary to provide suitable geometric conditions in order to assume the production and build-up coefficient to be the unit value (=1). To fulfill required conditions for this assumption, surface of the detector is covered with a 2 mm thick layer of cadmium. Radiation window of the detector has a 3 cm diameter, situated directly in front of the source. By placing the cadmium cover over the detector, variation of values verses thickness of absorbent layer, renders linear function behavior, making it possible to measure the macroscopic cross section. The next stage is applying the MCNP code by simulating F1 tally and cosine-cards for calculating Total Macroscopic Cross-Section. Validation of this study is achieved through comparison of simulation by the MCNP code and results rendered by experiment measurements.

  12. Quantum-state preparation and macroscopic entanglement in gravitational-wave detectors

    NASA Astrophysics Data System (ADS)

    Müller-Ebhardt, Helge; Rehbein, Henning; Li, Chao; Mino, Yasushi; Somiya, Kentaro; Schnabel, Roman; Danzmann, Karsten; Chen, Yanbei

    2009-10-01

    Long-baseline laser-interferometer gravitational-wave (GW) detectors are operating at a factor of ˜10 (in amplitude) above the standard quantum limit (SQL) within a broad frequency band (in the sense that Δf˜f ). Such a low-noise budget has already allowed the creation of a controlled 2.7 kg macroscopic oscillator with an effective eigenfrequency of 150 Hz and an occupation number of ˜200 . This result, along with the prospect for further improvements, heralds the possibility of experimentally probing macroscopic quantum mechanics (MQM)—quantum mechanical behavior of objects in the realm of everyday experience—using GW detectors. In this paper, we provide the mathematical foundation for the first step of a MQM experiment: the preparation of a macroscopic test mass into a nearly minimum-Heisenberg-limited Gaussian quantum state, which is possible if the interferometer’s classical noise beats the SQL in a broad frequency band. Our formalism, based on Wiener filtering, allows a straightforward conversion from the noise budget of a laser interferometer, in terms of noise spectra, into the strategy for quantum-state preparation and the quality of the prepared state. Using this formalism, we consider how Gaussian entanglement can be built among two macroscopic test masses and the performance of the planned Advanced LIGO interferometers in quantum-state preparation.

  13. High-throughput imaging of adult fluorescent zebrafish with an LED fluorescence macroscope

    PubMed Central

    Blackburn, Jessica S; Liu, Sali; Raimondi, Aubrey R; Ignatius, Myron S; Salthouse, Christopher D; Langenau, David M

    2011-01-01

    Zebrafish are a useful vertebrate model for the study of development, behavior, disease and cancer. A major advantage of zebrafish is that large numbers of animals can be economically used for experimentation; however, high-throughput methods for imaging live adult zebrafish had not been developed. Here, we describe protocols for building a light-emitting diode (LED) fluorescence macroscope and for using it to simultaneously image up to 30 adult animals that transgenically express a fluorescent protein, are transplanted with fluorescently labeled tumor cells or are tagged with fluorescent elastomers. These protocols show that the LED fluorescence macroscope is capable of distinguishing five fluorescent proteins and can image unanesthetized swimming adult zebrafish in multiple fluorescent channels simultaneously. The macroscope can be built and used for imaging within 1 day, whereas creating fluorescently labeled adult zebrafish requires 1 hour to several months, depending on the method chosen. The LED fluorescence macroscope provides a low-cost, high-throughput method to rapidly screen adult fluorescent zebrafish and it will be useful for imaging transgenic animals, screening for tumor engraftment, and tagging individual fish for long-term analysis. PMID:21293462

  14. Microstructural study of as sprayed and heat treated Ni3Al coatings deposited by air plasma spraying technique

    NASA Astrophysics Data System (ADS)

    Mehmood, K.; Rafiq, M. A.; Nusair Khan, A.; Rauf, M. M.

    2016-08-01

    Air plasma spraying system was utilized to deposit Ni3Al coatings on AISI 321 steel samples. After plasma spraying the coatings were heat treated at different temperatures i.e. 500 °C to 800 °C for 10 to 100 hours. The characterization tools such as, X-Ray diffraction analysis, optical and scanning electron microscopy were used. By comparing the XRD scan data of as sprayed and heat treated coating, it was observed that the formation of NiO increases drastically with time and temperature. Due to the formation of NiO, hardness was also enhanced. The oxidation behavior was observed by using optical microscope and when it was studied that the oxidation was increasing with time and temperature. Further, the SEM tool was utilized to study the detail microstructural behavior such as shrinkage cavity and oxide particles. The other phases like alumina and spinel phases were determined by using Energy dispersive spectrometer method.

  15. Basic Characteristics of a Macroscopic Measure for Detecting Abnormal Changes in a Multiagent System

    PubMed Central

    Kinoshita, Tetsuo

    2015-01-01

    Multiagent application systems must deal with various changes in both the system and the system environment at runtime. Generally, such changes have undesirable negative effects on the system. To manage and control the system, it is important to observe and detect negative effects using an appropriate observation function of the system’s behavior. This paper focuses on the design of this function and proposes a new macroscopic measure with which to observe behavioral characteristics of a runtime multiagent system. The proposed measure is designed as the variance of fluctuation of a macroscopic activity factor of the whole system, based on theoretical analysis of the macroscopic behavioral model of a multiagent system. Experiments are conducted to investigate basic characteristics of the proposed measure, using a test bed system. The results of experiments show that the proposed measure reacts quickly and increases drastically in response to abnormal changes in the system. Hence, the proposed measure is considered a measure that can be used to detect undesirable changes in a multiagent system. PMID:25897499

  16. Spray-by-spray in situ cross-linking alginate hydrogels delivering a tea tree oil microemulsion.

    PubMed

    Catanzano, O; Straccia, M C; Miro, A; Ungaro, F; Romano, I; Mazzarella, G; Santagata, G; Quaglia, F; Laurienzo, P; Malinconico, M

    2015-01-23

    In this paper we propose an in situ forming ionically cross-linked alginate (Alg) hydrogel delivering a Tea Tree Oil microemulsion (MeTTO) and potentially useful as an advanced dressing for infected wounds. Alg hydrogels were prepared by a spray-by-spray deposition method with the aim to minimize the discomforts during application. From pseudoternary phase diagrams, it was found that proper combination of TTO, water, polysorbate 80 and ethanol gave stable spherical MeTTO with good antimicrobial activity. On this basis, MeTTO at 20% TTO was selected for further inclusion in an Alg hydrogel prepared by alternating sprays of Alg/MeTTO and calcium chloride solutions. Homogeneous dispersion of MeTTO inside cross-linked Alg was assessed by different macroscopic and microscopic methods demonstrating the superior propensity of MeTTO to be integrated in the water-based hydrogel as compared to TTO. Antimicrobial effect of Alg/MeTTO hydrogels on Escherichia Coli strains was remarkable, highlighting the potential of the system as bioactive wound dressing.

  17. Spray characterization and turbulence properties in an isothermal spray with swirl

    SciTech Connect

    de la Rosa, A.B.; Bachalo, W.D.; Rudoff, R.C. )

    1990-01-01

    The present work reports an experimental study of the effect of swirl on the dynamic behavior of drops and on the velocity and turbulence fields of an isothermal spray using a two-component phase Doppler particle analyzer (PDPA). It represents the first phase of an effort to investigate the effect of swirl on the structure of liquid spray flames, the stability of the flame, and its effect on the emission of pollutants. A vane-type swirler was placed on the liquid supply tube of a pressure atomizer and tested in the wind tunnel under specified conditions. Mean velocity and turbulence properties were obtained for the gas phase. In addition, drop velocity and drop size distributions, particle number densities, and volume flux were measured at different locations within the swirling flow. Large differences in the spatial distribution of the drops over its size, velocity, and number density are observed when the spray in coflowing air with the same axial velocity is compared with the atomizer spraying into the swirling flow field. Large drops seem to be recirculated into the core of the swirling flow, while rather small drops surround this central region. The radial distribution of particle number density and the liquid volume flux are also different when the atomizer spraying into the coflowing air and into the swirling field are compared. Particle number densities for the latter exhibit higher peak values close to the nozzle; but show almost the same peak values as in the coflowing case but at a different radial location further downstream. The velocity of specific drop sizes was also obtained.

  18. INEL Spray-forming Research

    NASA Technical Reports Server (NTRS)

    Mchugh, Kevin M.; Key, James F.

    1993-01-01

    Spray forming is a near-net-shape fabrication technology in which a spray of finely atomized liquid droplets is deposited onto a suitably shaped substrate or mold to produce a coherent solid. The technology offers unique opportunities for simplifying materials processing without sacrificing, and oftentimes substantially improving, product quality. Spray forming can be performed with a wide range of metals and nonmetals, and offers property improvements resulting from rapid solidification (e.g., refined microstructures, extended solid solubilities and reduced segregation). Economic benefits result from process simplification and the elimination of unit operations. Researchers at the Idaho National Engineering Laboratory (INEL) are developing spray-forming technology for producing near-net-shape solids and coatings of a variety of metals, polymers, and composite materials. Results from several spray forming programs are presented to illustrate the range of capabilities of the technique as well as the accompanying technical and economic benefits. Low-carbon steel strip greater than 0.75 mm thick and polymer membranes for gas/gas and liquid/liquid separations that were spray formed are discussed; recent advances in spray forming molds, dies, and other tooling using low-melting-point metals are described.

  19. INEL spray-forming research

    SciTech Connect

    McHugh, K.M.; Key, J.F.

    1992-01-01

    Spray forming is a near-net-shape fabrication technology in which a spray of finely atomized liquid droplets is deposited onto a suitably shaped substrate or mold to produce a coherent solid. The technology offers unique opportunities for simplifying materials processing without sacrificing, and oftentimes substantially improving, product quality. Spray forming can be performed with a wide range of metals and nonmetals, and offers property improvements resulting from rapid solidification (e.g. refined microstructures, extended solid solubilities and reduced segregation). Economic benefits result from process simplification and the elimination of unit operations. Researchers at the Idaho National Engineering Laboratory (INEL) are developing spray-forming technology for producing near-net-shape solids and coatings of a variety of metals, polymers, and composite materials. Results from several spray-forming programs are presented to illustrate the range of capabilities of the technique as well as the accompanying technical and economic benefits. Low-carbon steel strip >0.75 mm thick and polymer membranes for gas/gas and liquid/liquid separations that were spray formed are discussed; recent advances in spray forming molds, dies, and other tooling using low-melting-point metals are described.

  20. A fluorescent tracer method for evaluating spray transport and fate of field and laboratory spray applications

    USDA-ARS?s Scientific Manuscript database

    Field and laboratory testing spray nozzles and application systems use spray collectors to assess where the spray deposits once it leaves the spray system. Tracer materials, such as oil and water soluble fluorescent dyes, can be mixed into spray solutions in small amounts with minimal impact on the...

  1. Cold Spray Technology for DOD Applications

    DTIC Science & Technology

    2012-08-01

    Distribution Unlimited Mechanical Mixing at Interface • .. Sm-in ,, aluminum Approved for Public Release; Distribution Unlimited Cold Spray vs...of Corrosion Damage on Fielded Parts and Subsequent to Cold Spray Repair Before After 15 Cold Spray HP- Aluminum Fill...Unlimited Development and Implementation of Commercially Pure (CP) Aluminum and 6061 Aluminum Alloy Cold Spray Coatings for the Repair of Magnesium

  2. Towards a macroscopic modeling of the complexity in traffic flow.

    PubMed

    Rosswog, Stephan; Wagner, Peter

    2002-03-01

    Based on the assumption of a safe velocity U(e)(rho) depending on the vehicle density rho, a macroscopic model for traffic flow is presented that extends the model of the Kühne-Kerner-Konhäuser by an interaction term containing the second derivative of U(e)(rho). We explore two qualitatively different forms of U(e): a conventional Fermi-type function and, motivated by recent experimental findings, a function that exhibits a plateau at intermediate densities, i.e., in this density regime the exact distance to the car ahead is only of minor importance. To solve the fluid-like equations a Lagrangian particle scheme is developed. The suggested model shows a much richer dynamical behavior than the usual fluid-like models. A large variety of encountered effects is known from traffic observations, many of which are usually assigned to the elusive state of "synchronized flow." Furthermore, the model displays alternating regimes of stability and instability at intermediate densities. It can explain data scatter in the fundamental diagram and complicated jam patterns. Within this model, a consistent interpretation of the emergence of very different traffic phenomena is offered: they are determined by the velocity relaxation time, i.e., the time needed to relax towards U(e)(rho). This relaxation time is a measure of the average acceleration capability and can be attributed to the composition (e.g., the percentage of trucks) of the traffic flow.

  3. Single-file diffusion of macroscopic charged particles.

    PubMed

    Coste, C; Delfau, J-B; Even, C; Saint Jean, M

    2010-05-01

    In this paper, we study a macroscopic system of electrically interacting metallic beads organized as a sequence along an annulus. A random mechanical shaking mimics the thermal excitation. We exhibit non-Fickian diffusion (single-file diffusion) at large time. We measure the mobility of the particles and compare it to theoretical expectations. We show that our system cannot be accurately described by theories assuming only hard-sphere interactions. Its behavior is qualitatively described by a theory extended to more realistic potentials [M. Kollmann, Phys. Rev. Lett. 90, 180602 (2003)]. A correct quantitative agreement is shown and we interpret the discrepancies by the violation of the assumption of overdamped dynamics, which is a key point in the theory. We recast previous results on colloids with known interaction potentials and compare them quantitatively to the theory. Focusing on the transition between ordinary and single-file diffusions, we exhibit a dimensionless crossover time that is of order 1 both for colloids and our system, although the time and length scales differ by several orders of magnitude.

  4. Accumulation of small protein molecules in a macroscopic complex coacervate.

    PubMed

    Lindhoud, Saskia; Claessens, Mireille M A E

    2016-01-14

    To obtain insight into the accumulation of proteins into macroscopic complex coacervate phases, the lysozyme concentration in complex coacervates containing the cationic polyelectrolyte poly-(N,N dimethylaminoethyl methacrylate) and the anionic polyelectrolyte polyacrylic acid was investigated as a function of the mixing ratio, protein concentration and ionic strength. Maximal protein enrichment of the complex coacervate phase was observed to require the presence of all three macromolecules. Under optimized conditions the protein concentrations in the complex coacervate were as high as 200 g L(-1). Such high concentrations are comparable to the protein concentration in the cytosol, suggesting that these interesting liquid phases may serve a suitable model system for the phase behavior of the cytosol and genesis and function of membrane-less organelles. The high stability of the complexes and the salt dependent uptake of protein suggest that complex coacervates may provide a way to store hydrated proteins at high concentrations and might therefore be of interest in the formulation of high protein foods.

  5. Gas Dynamic Spray Technology Demonstration

    NASA Technical Reports Server (NTRS)

    Burford, Pattie Lewis

    2011-01-01

    Zinc primer systems are currently used across NASA and AFSPC for corrosion protection of steel. AFSPC and NASA have approved the use of Thermal Spray Coatings (TSCs) as an environmentally preferable alternative. TSCs are approved in NASA-STD-5008 and AFSPC and KSC is currently looking for additional applications in which TSC can be used. Gas Dynamic Spray (GDS, also known as Cold Spray) is being evaluated as a means of repairing TSCs and for areas such as corners and edges where TSCs do not work as well. Other applications could include spot repair/maintenance of steel on structures, facilities, and ground support equipment.

  6. Plasma spraying with wire feedstock

    SciTech Connect

    Scholl, M.

    1994-12-31

    Plasma spraying has been limited to using powder feedstocks for a number of reasons. One limitation has been the low energy output of conventional plasma guns. The advent of high energy plasma spraying (HEPS) devices and the associated technology has effectively removed this functional limitation. With HEPS, the combination of high gas velocities and high thermal plasma temperatures coupled with a large exit gas volume enables wire and rod feedstocks to be effectively utilized. Rather than a bulk melting mechanism, a model based on ablation phenomena is considered. The paper examines an analysis of melting phenomena and presents a simple model for molten droplet formation for plasma spraying using wire feedstocks.

  7. A Macroscopic Model for a System of Swarming Agents Using Curvature Control

    NASA Astrophysics Data System (ADS)

    Degond, Pierre; Motsch, Sébastien

    2011-05-01

    In this paper, we study the macroscopic limit of a new model of collective displacement. The model, called PTWA, is a combination of the Vicsek alignment model (Vicsek et al. in Phys. Rev. Lett. 75(6):1226-1229, 1995) and the Persistent Turning Walker (PTW) model of motion by curvature control (Degond and Motsch in J. Stat. Phys. 131(6):989-1021, 2008; Gautrais et al. in J. Math. Biol. 58(3):429-445, 2009). The PTW model was designed to fit measured trajectories of individual fish (Gautrais et al. in J. Math. Biol. 58(3):429-445, 2009). The PTWA model (Persistent Turning Walker with Alignment) describes the displacements of agents which modify their curvature in order to align with their neighbors. The derivation of its macroscopic limit uses the non-classical notion of generalized collisional invariant introduced in (Degond and Motsch in Math. Models Methods Appl. Sci. 18(1):1193-1215, 2008). The macroscopic limit of the PTWA model involves two physical quantities, the density and the mean velocity of individuals. It is a system of hyperbolic type but is non-conservative due to a geometric constraint on the velocity. This system has the same form as the macroscopic limit of the Vicsek model (Degond and Motsch in Math. Models Methods Appl. Sci. 18(1):1193-1215, 2008) (the `Vicsek hydrodynamics') but for the expression of the model coefficients. The numerical computations show that the numerical values of the coefficients are very close. The `Vicsek Hydrodynamic model' appears in this way as a more generic macroscopic model of swarming behavior as originally anticipated.

  8. Modeling spray/puddle dissolution processes for deep-ultraviolet acid-hardened resists

    NASA Astrophysics Data System (ADS)

    Hutchinson, John M.; Das, Siddhartha; Qian, Qi-De; Gaw, Henry T.

    1993-10-01

    A study of the dissolution behavior of acid-hardened resists (AHR) was undertaken for spray and spray/puddle development processes. The Site Services DSM-100 end-point detection system is used to measure both spray and puddle dissolution data for a commercially available deep-ultraviolet AHR resist, Shipley SNR-248. The DSM allows in situ measurement of dissolution rate on the wafer chuck and hence allows parameter extraction for modeling spray and puddle processes. The dissolution data for spray and puddle processes was collected across a range of exposure dose and postexposure bake temperature. The development recipe was varied to decouple the contribution of the spray and puddle modes to the overall dissolution characteristics. The mechanisms involved in spray versus puddle dissolution and the impact of spray versus puddle dissolution on process performance metrics has been investigated. We used the effective-dose-modeling approach and the measurement capability of the DSM-100 and developed a lumped parameter model for acid-hardened resists that incorporates the effects of exposure, postexposure bake temperature and time, and development condition. The PARMEX photoresist-modeling program is used to determine parameters for the spray and for the puddle process. The lumped parameter AHR model developed showed good agreement with experimental data.

  9. The Correlation Between the Coating Quality and the Moving Direction of the Twin Wire Arc Spraying Gun

    NASA Astrophysics Data System (ADS)

    Tillmann, W.; Vogli, E.; Abdulgader, M.

    2010-01-01

    Asymmetric melting behavior of the electrodes is a process-related feature of the twin wire arc spraying (TWAS) technique since the heating of the negative wire is different from that of the positive wire. The asymmetric melting behavior, particle crossover, irregular plume shape, and last but not least the arc voltage fluctuations affect the spraying jet on the whole and lead to an inhomogeneous plume. To investigate the effect of inhomogeneous spraying plume on coating characteristics, coatings were produced by moving the spraying gun in different directions, with respect to the electrodes. The porosity, micro-cracks, hardness, thickness, and adhesion strength of the sprayed coatings were measured and brought in correlation with the gun moving direction. In this study, two different wire types were investigated in order to find out the effect of the spraying gun moving direction on the coating quality.

  10. Exposure of spray-men to dieldrin in residual spraying.

    PubMed

    FLETCHER, T E; PRESS, J M; WILSON, D B

    1959-01-01

    A study of the exposure of spray-men to dieldrin was made in a pilot scheme of residual spraying in the Taveta-Pare area of East Africa. A detailed work study was completed on the operators, and sources of contamination were enumerated. Filter paper pads were placed on the skin and outside clothing and the pick-up was estimated chemically. A spray-man, while using the daily average of 2.12 kg (4.7 pounds) of dieldrin and observing the protective measures laid down, received a dermal exposure of 1.8 mg of dieldrin per kg of body-weight per day. This was possibly reduced somewhat by washing with soap and water upon completion of each day's work. The sixteen spray-men and assistants were exposed for 180 days per year and there was an interim period of 2 months between spray cycles. No clinical symptoms of poisoning were observed.Comparison is made with certain programmes where dieldrin poisoning has occurred. Attention is drawn to the reduced time of exposure in the Taveta-Pare scheme, personal washing, the great value of protective clothing and of its daily washing in soap and water and the need to use a dilute suspension of wettable powder for spraying.

  11. Investigation of vortex clouds and droplet sizes in heated water spray patterns generated by axisymmetric full cone nozzles.

    PubMed

    Naz, M Y; Sulaiman, S A; Ariwahjoedi, B; Ku Shaari, Ku Zilati

    2013-01-01

    The hot water sprays are an important part of many industrial processes, where the detailed knowledge of physical phenomena involved in jet transportation, interaction, secondary breakup, evaporation, and coalescence of droplets is important to reach more efficient processes. The objective of the work was to study the water spray jet breakup dynamics, vortex cloud formation, and droplet size distribution under varying temperature and load pressure. Using a high speed camera, the spray patterns generated by axisymmetric full cone nozzles were visualized as a function water temperature and load pressure. The image analysis confirmed that the spray cone angle and width do not vary significantly with increasing Reynolds and Weber numbers at early injection phases leading to increased macroscopic spray propagation. The formation and decay of semitorus like vortex clouds were also noticed in spray structures generated at near water boiling point temperature. For the nozzle with smallest orifice diameter (1.19 mm), these vortex clouds were very clear at 90°C heating temperature and 1 bar water load pressure. In addition, the sauter mean diameter (SMD) of the spray droplets was also measured by using Phase Doppler Anemometry (PDA) at different locations downstream of the nozzle exit. It was noticed that SMD varies slightly w.r.t. position when measured at room temperature whereas at higher temperature values, it became almost constant at distance of 55 mm downstream of the nozzle exit.

  12. Modifications Of A Commercial Spray Gun

    NASA Technical Reports Server (NTRS)

    Allen, Peter B.

    1993-01-01

    Commercial spray gun modified to increase spray rate and make sprayed coats more nearly uniform. Consists of gun head and pneumatic actuator. Actuator opens valves for two chemical components, called "A" and "B," that react to produce foam. Components flow through orifices, into mixing chamber in head. Mixture then flows through control orifice to spray tip. New spray tip tapered to reduce area available for accumulation of foam and makes tip easier to clean.

  13. Modifications Of A Commercial Spray Gun

    NASA Technical Reports Server (NTRS)

    Allen, Peter B.

    1993-01-01

    Commercial spray gun modified to increase spray rate and make sprayed coats more nearly uniform. Consists of gun head and pneumatic actuator. Actuator opens valves for two chemical components, called "A" and "B," that react to produce foam. Components flow through orifices, into mixing chamber in head. Mixture then flows through control orifice to spray tip. New spray tip tapered to reduce area available for accumulation of foam and makes tip easier to clean.

  14. Experimental demonstration of macroscopic quantum coherence in Gaussian states

    SciTech Connect

    Marquardt, Christoph; Leuchs, Gerd; Andersen, Ulrik L.; Takeno, Yuishi; Yukawa, Mitsuyoshi; Yonezawa, Hidehiro; Furusawa, Akira

    2007-09-15

    We witness experimentally the presence of macroscopic coherence in Gaussian quantum states using a recently proposed criterion [E. G. Cavalcanti and M. D. Reid, Phys. Rev. Lett. 97 170405 (2006)]. The macroscopic coherence stems from interference between macroscopically distinct states in phase space, and we prove experimentally that a coherent state contains these features with a distance in phase space of 0.51{+-}0.02 shot noise units. This is surprising because coherent states are generally considered being at the border between classical and quantum states, not yet displaying any nonclassical effect. For squeezed and entangled states the effect may be larger but depends critically on the state purity.

  15. Estimation of equivalence ratio distribution in diesel spray using a computational fluid dynamics

    NASA Astrophysics Data System (ADS)

    Suzuki, Yasumasa; Tsujimura, Taku; Kusaka, Jin

    2014-08-01

    It is important to understand the mechanism of mixing and atomization of the diesel spray. In addition, the computational prediction of mixing behavior and internal structure of a diesel spray is expected to promote the further understanding about a diesel spray and development of the diesel engine including devices for fuel injection. In this study, we predicted the formation of diesel fuel spray with 3D-CFD code and validated the application by comparing experimental results of the fuel spray behavior and the equivalence ratio visualized by Layleigh-scatter imaging under some ambient, injection and fuel conditions. Using the applicable constants of KH-RT model, we can predict the liquid length spray on a quantitative level. under various fuel injection, ambient and fuel conditions. On the other hand, the change of the vapor penetration and the fuel mass fraction and equivalence ratio distribution with change of fuel injection and ambient conditions quantitatively. The 3D-CFD code used in this study predicts the spray cone angle and entrainment of ambient gas are predicted excessively, therefore there is the possibility of the improvement in the prediction accuracy by the refinement of fuel droplets breakup and evaporation model and the quantitative prediction of spray cone angle.

  16. Microstructural characteristics of plasma sprayed nanostructured partially stabilized zirconia

    NASA Astrophysics Data System (ADS)

    Lima, Rogerio Soares

    Thermal barrier coatings have been extensively applied in the aerospace industry in turbines and rocket engines as an insulation system. Partially stabilized zirconia, due to its high thermal stability and low thermal conductivity at high temperatures has been traditionally employed as the ceramic element of the thermal barrier coating system. Different approaches have been taken in order to improve the performance of these coatings. Nanostructured materials are promising an interesting future in the beginning of the 21st century. Due to its enhanced strain to failure and superplasticity new applications may be accomplished or the limits of materials utilization may be placed at higher levels. Single nanostructured particles can not be thermal sprayed by conventional thermal spray equipment. Due to its low mass, they would be deviated to the periphery of the thermal spray jet. To overcome this characteristic, single nanostructured particles were successively agglomerated into large microscopic particles, with particle size distribution similar to the conventional feedstocks for thermal spray equipment. Agglomerated nanostructured particles of partially stabilized zirconia were plasma sprayed in air with different spray parameters. According to traditional thermal spray procedure, the feedstock has to be melted in the thermal spray jet in order to achieve the necessary conditions for adhesion and cohesion on the substrate. Due to the nature of the nanostructured particles, a new step has to be taken in the thermal spray processing; particle melting has to be avoided in order to preserve the feedstock nanostructure in the coating overall microstructure. In this work, the adhesion/cohesion system of nanostructured coatings is investigated and clarified. A percentage of molten particles will retain and hold the non-molten agglomerated nanostructured particles in the coating overall microstructure. Controlling the spray parameters it was possible to produce coatings

  17. Process Sprays Uniforms Plasma Coatings

    NASA Technical Reports Server (NTRS)

    Sliney, H. E.; Jacobson, T. P.; Walther, G. C.; Nakamura, H. H.

    1983-01-01

    Composite-powder processing procedure developed along with plasma-spray parameters to achieve homogeneous, well-bonded, low-porosity, self-lubricating coatings. Multicomponent plasma coatings are applied without segretation of components.

  18. Spray nozzle for fire control

    NASA Astrophysics Data System (ADS)

    Papavergos, Panayiotis G.

    1990-09-01

    The design of a spray nozzle for fire control is described. It produces a spray of gas and liquid having an oval transverse cross section and it comprises a mixing chamber with an oval transverse cross section adapted to induce a toroidal mixing pattern in pressurized gas and liquid introduced to the mixing chamber through a plurality of inlets. In a preferred embodiment the mixing chamber is toroidal. The spray nozzle produces an oval spray pattern for more efficient wetting of narrow passages and is suitable for fire control systems in vehicles or other confined spaces. Vehicles to which this invention may be applied include trains, armoured vehicles, ships, hovercraft, submarines, oil rigs, and most preferably, aircraft.

  19. Some work and some play: microscopic and macroscopic approaches to labor and leisure.

    PubMed

    Niyogi, Ritwik K; Shizgal, Peter; Dayan, Peter

    2014-12-01

    Given the option, humans and other animals elect to distribute their time between work and leisure, rather than choosing all of one and none of the other. Traditional accounts of partial allocation have characterised behavior on a macroscopic timescale, reporting and studying the mean times spent in work or leisure. However, averaging over the more microscopic processes that govern choices is known to pose tricky theoretical problems, and also eschews any possibility of direct contact with the neural computations involved. We develop a microscopic framework, formalized as a semi-Markov decision process with possibly stochastic choices, in which subjects approximately maximise their expected returns by making momentary commitments to one or other activity. We show macroscopic utilities that arise from microscopic ones, and demonstrate how facets such as imperfect substitutability can arise in a more straightforward microscopic manner.

  20. Simulation and verification of macroscopic isotropy of hollow alginate-based microfibers.

    PubMed

    Djomehri, Sabra; Zeid, Hanaa; Yavari, Alireza; Mobed-Miremadi, Maryam; Youssefi, Kenneth; Liao-Chan, Sindy

    2015-01-01

    A simulation of tensile strength of various alginate-based hollow microfibers using FEA analysis has been conducted with the hypothesis of macroscopic isotropy and linear elastic-plastic behavior. Results of student t-tests indicated that there was no significant difference between the experimental and simulated tensile strengths (p = 0.37, α = 0.05), while there was a significant reduction in elasticity as a result of chitosan coating (p = 0.024, α = 0.05). The hypothesis of macroscopic isotropy was verified by highly correlated (R(2) ≥ 0.92) theoretical and experimental elongation at break measurements, findings that could be extended to the failure analysis of alginate microfibers used in regenerative medicine.

  1. Some Work and Some Play: Microscopic and Macroscopic Approaches to Labor and Leisure

    PubMed Central

    Niyogi, Ritwik K.; Shizgal, Peter; Dayan, Peter

    2014-01-01

    Given the option, humans and other animals elect to distribute their time between work and leisure, rather than choosing all of one and none of the other. Traditional accounts of partial allocation have characterised behavior on a macroscopic timescale, reporting and studying the mean times spent in work or leisure. However, averaging over the more microscopic processes that govern choices is known to pose tricky theoretical problems, and also eschews any possibility of direct contact with the neural computations involved. We develop a microscopic framework, formalized as a semi-Markov decision process with possibly stochastic choices, in which subjects approximately maximise their expected returns by making momentary commitments to one or other activity. We show macroscopic utilities that arise from microscopic ones, and demonstrate how facets such as imperfect substitutability can arise in a more straightforward microscopic manner. PMID:25474151

  2. Effects of Turbulence Characteristics in the Spray Combustion

    NASA Astrophysics Data System (ADS)

    Takeuchi, Seiichi; Douhara, Noriyoshi

    The present study was conducted in order to clarify the effects of airflow turbulence on the spray combustion. Methanol was atomized with the two-fluid-type nozzle in order to generate the spray flame, and the turbulence characteristic of the flame was varied by inserting a mesh near the tip of the nozzle. Droplets in the spray flame were measured using a PDPA system in a reaction field, and changes in the turbulence characteristic were measured using a hot-wire anemometer in a no-reaction field in order to clarify the effects of turbulence on combustion behavior. Inserting a finer mesh promoted droplet evaporation and enhanced the dispersion characteristic. Regarding changes in the turbulence characteristic, the integral time scale increased and the energy spectrum decreased as the inserted mesh became finer. Based on the obtained results, we determined that a finer mesh causes vortexes to be more persistent and enhances the dispersion characteristic of the droplets.

  3. Macroscopic quantum tunnelling of protons in the KHCO 3 crystal

    NASA Astrophysics Data System (ADS)

    Fillaux, François; Cousson, Alain; Gutmann, Matthias J.

    2006-06-01

    Macroscopic quantum entanglement reveals an unforeseen mechanism for proton transfer across hydrogen bonds in the solid state. We utilize neutron scattering techniques to study proton dynamics in the crystal of potassiumhydrogencarbonate (KHCO 3) composed of small planar centrosymmetric dimer entities ( linked by moderately strong hydrogen bonds. All protons are indistinguishable, they behave as fermions, and they are degenerate. The sublattice of protons is a superposition of macroscopic single-particle states. At elevated temperature, protons are progressively transferred to secondary sites at ≈0.6 Å from the main position, via tunnelling along hydrogen bonds. The macroscopic quantum entanglement, still observed at 300 K, reveals that proton transfer is a coherent process throughout the crystal arising from a superposition of macroscopic tunnelling states.

  4. Large Deviations for the Macroscopic Motion of an Interface

    NASA Astrophysics Data System (ADS)

    Birmpa, P.; Dirr, N.; Tsagkarogiannis, D.

    2017-03-01

    We study the most probable way an interface moves on a macroscopic scale from an initial to a final position within a fixed time in the context of large deviations for a stochastic microscopic lattice system of Ising spins with Kac interaction evolving in time according to Glauber (non-conservative) dynamics. Such interfaces separate two stable phases of a ferromagnetic system and in the macroscopic scale are represented by sharp transitions. We derive quantitative estimates for the upper and the lower bound of the cost functional that penalizes all possible deviations and obtain explicit error terms which are valid also in the macroscopic scale. Furthermore, using the result of a companion paper about the minimizers of this cost functional for the macroscopic motion of the interface in a fixed time, we prove that the probability of such events can concentrate on nucleations should the transition happen fast enough.

  5. Macroscopic test of quantum mechanics versus stochastic electrodynamics

    NASA Astrophysics Data System (ADS)

    Chaturvedi, S.; Drummond, Peter D.

    1997-02-01

    We identify a test of quantum mechanics versus macroscopic local realism in the form of stochastic electrodynamics. The test uses the steady-state triple quadrature correlations of a parametric oscillator below threshold.

  6. Anatomy of the ethmoid: CT, endoscopic, and macroscopic

    SciTech Connect

    Terrier, F.; Weber, W.; Ruefenacht, D.; Porcellini, B.

    1985-03-01

    The authors illustrate the normal CT anatomy of the ethmoid region and correlate it with the endoscopic and macroscopic anatomy to define landmarks that can be recognized on CT and during endoscopically controlled transnasal ethmoidectomy.

  7. Hydrodynamics of Moving Contact Lines: Macroscopic versus Microscopic.

    PubMed

    Lukyanov, Alex V; Pryer, Tristan

    2017-08-29

    The fluid-mechanics community is currently divided in assessing the boundaries of applicability of the macroscopic approach to fluid mechanical problems. Can the dynamics of nanodroplets be described by the same macroscopic equations as are used for macrodroplets? To the greatest degree, this question should be addressed to the moving-contact-line problem. The problem is naturally multiscale, where even using slip boundary conditions results in spurious numerical solutions and transcendental stagnation regions in modeling in the vicinity of the contact line. In this article, it is demonstrated through mutual comparisons between macroscopic modeling and molecular dynamics simulations that a small, albeit natural, change in the boundary conditions is all that is necessary to completely regularize the problem and eliminate these nonphysical effects. The limits of the macroscopic approach applied to the moving-contact-line problem have been tested and validated on the basis of microscopic first-principles molecular dynamics simulations.

  8. Chaotic macroscopic phases in one-dimensional oscillators

    NASA Astrophysics Data System (ADS)

    Politi, Antonio; Pikovsky, Arkady; Ullner, Ekkehard

    2017-06-01

    The connection between the macroscopic description of collective chaos and the underlying microscopic dynamics is thoroughly analysed in mean-field models of one-dimensional oscillators. We investigate to what extent infinitesimal perturbations of the microscopic configurations can provide information also on the stability of the corresponding macroscopic phase. In ensembles of identical one-dimensional dynamical units, it is possible to represent the microscopic configurations so as to make transparent their connection with the macroscopic world. As a result, we find evidence of an intermediate, mesoscopic, range of distances, over which the instability is neither controlled by the microscopic equations nor by the macroscopic ones. We examine a whole series of indicators, ranging from the usual microscopic Lyapunov exponents, to the collective ones, including finite-amplitude exponents. A system of pulse-coupled oscillators is also briefly reviewed as an example of non-identical phase oscillators where collective chaos spontaneously emerges.

  9. Interference of macroscopic states in the presence of quantum tunneling

    SciTech Connect

    Dmitrenko, I.M.; Tsoi, G.M.; Shnyrkov, V.I.

    1984-02-01

    In studying the decomposition of the metastable states of superconducting quantum interferrometers, anomalous peaks were observed in the probability density, whose appearance is associated with resonance tunneling between macroscopic states.

  10. Terahertz Science and Technology of Macroscopically Aligned Carbon Nanotube Films

    NASA Astrophysics Data System (ADS)

    Kono, Junichiro

    One of the outstanding challenges in nanotechnology is how to assemble individual nano-objects into macroscopic architectures while preserving their extraordinary properties. For example, the one-dimensional character of electrons in individual carbon nanotubes leads to extremely anisotropic transport, optical, and magnetic phenomena, but their macroscopic manifestations have been limited. Here, we describe methods for preparing macroscopic films, sheets, and fibers of highly aligned carbon nanotubes and their applications to basic and applied terahertz studies. Sufficiently thick films act as ideal terahertz polarizers, and appropriately doped films operate as polarization-sensitive, flexible, powerless, and ultra-broadband detectors. Together with recently developed chirality enrichment methods, these developments will ultimately allow us to study dynamic conductivities of interacting one-dimensional electrons in macroscopic single crystals of single-chirality single-wall carbon nanotubes.

  11. Conditional preparation of X{sup (2)} macroscopic entangled states

    SciTech Connect

    Podoshvedov, S. A.

    2006-04-15

    Two experimental arrangements consisting of coupled spontaneous parametric down-converters with type-I phase matching pumped simultaneously by a powerful optical field in a coherent state through a balanced beam splitter and linear optical elements are proposed for conditional preparation of macroscopic entangled states in output pumping modes of the studied system. Successful generation of the macroscopic entangled state in the pumping modes is unambiguously heralded by coincident detection of two photons in the generated signal and idler modes of the system. We calculate the amount of entanglement and probabilities of successfully observing the X{sup (2)} macroscopic entangled states in the total wavefunction. We show that the proposed schemes can be used to obtain a new type of macroscopic entangled states.

  12. Milestones in Functional Titanium Dioxide Thermal Spray Coatings: A Review

    NASA Astrophysics Data System (ADS)

    Gardon, M.; Guilemany, J. M.

    2014-04-01

    Titanium dioxide has been the most investigated metal oxide due to its outstanding performance in a wide range of applications, chemical stability and low cost. Coating processes that can produce surfaces based on this material have been deeply studied. Nevertheless, the necessity of coating large areas by means of rapid manufacturing processes renders laboratory-scale techniques unsuitable, leading to a noteworthy interest from the thermal spray (TS) community in the development of significant intellectual property and a large number of scientific publications. This review unravels the relationship between titanium dioxide and TS technologies with the aim of providing detailed information related to the most significant achievements, lack of knowhow, and performance of TS TiO2 functional coatings in photocatalytic, biomedical, and other applications. The influence of thermally activated techniques such as atmospheric plasma spray and high-velocity oxygen fuel spray on TiO2 feedstock based on powders and suspensions is revised; the influence of spraying parameters on the microstructural and compositional changes and the final active behavior of the coating have been analyzed. Recent findings on titanium dioxide coatings deposited by cold gas spray and the capacity of this technology to prevent loss of the nanostructured anatase metastable phase are also reviewed.

  13. Crack Repair in Aerospace Aluminum Alloy Panels by Cold Spray

    NASA Astrophysics Data System (ADS)

    Cavaliere, P.; Silvello, A.

    2017-02-01

    The cold-spray process has recently been recognized as a very useful tool for repairing metallic sheets, achieving desired adhesion strengths when employing optimal combinations of material process parameters. We present herein the possibility of repairing cracks in aluminum sheets by cold spray. A 2099 aluminum alloy panel with a surface 30° V notch was repaired by cold spraying of 2198 and 7075 aluminum alloy powders. The crack behavior of V-notched sheets subjected to bending loading was studied by finite-element modeling (FEM) and mechanical experiments. The simulations and mechanical results showed good agreement, revealing a remarkable K factor reduction, and a consequent reduction in crack nucleation and growth velocity. The results enable prediction of the failure initiation locus in the case of repaired panels subjected to bending loading and deformation. The stress concentration was quantified to show how the residual stress field and failure are affected by the mechanical properties of the sprayed materials and by the geometrical and mechanical properties of the interface. It was demonstrated that the crack resistance increases more than sevenfold in the case of repair using AA2198 and that cold-spray repair can contribute to increased global fatigue life of cracked structures.

  14. Wear mechanisms in thermally-sprayed Mo-based coatings

    NASA Astrophysics Data System (ADS)

    Wayne, S. F.; Sampath, S.; Anand, V.

    1994-07-01

    The successful development of advanced diesel engines relies heavily on piston ring coating materials which can withstand elevated temperatures and reduce friction. Traditional hard chrome plating and flame-sprayed Mo-wire materials have reached their potential in the diesel engine environment, and alternatives are needed. Thermally-sprayed Mo-based alloys and composites are being evaluated for applications as next-generation ring-face coatings. The alloy development task of producing complex Mo-based alloy powders for use as thermally-sprayed coating materials requires an understanding of their wear resistance under contact stress conditions. In this paper, the wear behavior of Mo and Mo + NiCrBSi thermally sprayed coatings is exmined by pin-on-disc and single-point scratch-test methods. Microstructural analysis beneath worn regions have revealed that fracture of splats and their decohesion constitute the mode of failure. Improved wear resistance and stability of low friction coefficient was obtained by prealloying Mo with NiCrBSi prior to thermal spraying.

  15. Crystallization Evolution of Cold-Sprayed Pure Ni Coatings

    NASA Astrophysics Data System (ADS)

    Cavaliere, P.; Perrone, A.; Silvello, A.

    2016-08-01

    Cold spraying is a coating technology on the basis of aerodynamics and high-speed impact dynamics. Spray particles (usually 1-50 μm in diameter) are accelerated to high velocity (typically 300-1200 m/s) by a high-speed gas (preheated air, nitrogen, or helium) flow that is generated through a convergent-divergent de Laval type nozzle. The coating forms through the intensive plastic deformation of particles impacting on the substrate at temperatures well below the melting point of the spray material. In the present paper, the main processing parameters affecting the crystallization behavior of pure Ni cold spray deposits on IN718 alloy are described. Various experimental conditions have been analyzed: gas temperature and pressure, nozzle to substrate distance. In particular, the study deals with those conditions leading to a strong grain refinement, with an acceptable level of the deposits mechanical properties. In precise spray conditions, a shift toward amorphous phases has been observed and studied. A systematic analysis of microstructural evolution, performed through TEM observations, as a function of processing parameters is presented.

  16. Electronic Structure Calculations at Macroscopic Scales

    DTIC Science & Technology

    2012-02-02

    to satisfy the Lindhard response function—a known limiting behavior of uniform electron gas. The Wang- Govind -Carter (WGC) kinetic energy functional... R ., QTT Representation of the Hartree and Ex- change Operators in Electronic Structure Calculations. MPI MIS preprint 37/2011 (2011). Kolda, T.G...2010). Wang, L., Teter, M.P., Kinetic energy functional of electron density. Phys. Rev. B, 45, 13196 (1992). Wang Y.A., Govind , N., Carter, E.A

  17. Microchip sonic spray ionization.

    PubMed

    Pól, Jaroslav; Kauppila, Tiina J; Haapala, Markus; Saarela, Ville; Franssila, Sami; Ketola, Raimo A; Kotiaho, Tapio; Kostiainen, Risto

    2007-05-01

    The first microchip version of sonic spray ionization (SSI) as an atmospheric pressure ionization source for mass spectrometry (MS) is presented. The microchip used for SSI has recently been developed in our laboratory, and it has been used before as an atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) source. Now the ionization is achieved simply by applying high (sonic) speed nebulizer gas, without heat, corona discharge, or high voltage. The microchip SSI was applied to the analysis of tetra-N-butylammonium, verapamil, testosterone, angiotensin I, and ibuprofen. The limits of detection were in the range of 15 nM to 4 microM. The technique was found to be highly dependent on the position of the chip toward the mass spectrometer inlet, and on the gas and the sample solution flow rates. The microchip SSI provided dynamic linearity following a pattern similar to that used with electrospray, good quantitative repeatability (RSD=16%), and long-term signal stability.

  18. Plasma Sprayed Hydroxyapatite Coatings: Influence of Spraying Power on Microstructure

    SciTech Connect

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

    2010-03-11

    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.

  19. Comparison of the performance between a spray gun and a spray boom in ornamentals.

    PubMed

    Foqué, D; Nuyttens, D

    2011-01-01

    Flemish greenhouse growers predominantly use handheld spray guns and spray lances for their crop protection purposes although these techniques are known for their heavy workload and their high operator exposure risks. Moreover, when these techniques are compared with spray boom equipment, they are often found to be less effective. On the other hand, handheld spraying techniques are less expensive and more flexible to use. Additionally, many Flemish growers are convinced that a high spray volume and spray pressure is needed to assure a good plant protection. The aim of this work was to evaluate and compare the spray deposition, penetration and uniformity between a manually pulled horizontal spray boom and a spray gun under controlled laboratory conditions. In total, six different spray application techniques were evaluated. In general, the total deposition results were comparable between the spray boom and the spray gun applications but the boom applications resulted in a more uniform spray distribution over the crop. On a plant level, the spray distribution was not uniform for the different techniques with highest deposits on the upper side of the top leaves. Using spray guns at a higher spray pressure did not improve spray penetration and deposition on the bottom side of the leaves. From the different nozzle types, the XR 80 03 gave the best results. Plant density clearly affected crop penetration and deposition on the bottom side of the leaves.

  20. Visualization of Electrohydrodynamic Effects and Time Scale Analysis for Impinging Spray Droplets of HFE-7000

    SciTech Connect

    Kreitzer, Paul J.; Kuhlman, John M.

    2008-01-21

    Spray cooling is becoming a leading technique for removing excess heat from high heat flux electronics. Electrohydrodynamic effects have been found to result in significant variation in spray behavior once the applied voltage level is increased enough to reach the Rayleigh limit. In the present work the dielectric coolant HFE-7000 has been used to study spray cooling heat transfer across a thick film resistor heater mounted to a 16 mm diameter pedestal. Heater power levels have been varied from 0 to 80 Watts, with spray flow rates varied from 2 GPH to 6 GPH (2.1x10{sup -6} m{sup 3}/s to 6.3x10{sup -6} m{sup 3}/s). Applied voltage levels between 0 kV and 30 kV with both positive and negative polarity have been applied directly to the brass spray nozzle, resulting in contact charging of the spray. A high-speed video camera was used to study behavior of both the impinging spray and the liquid film that formed on the heater surface. The contact charging was observed to lead to electrostatic atomization or 'breakup' of the droplets. Time scale estimates of the various physical processes within the spray and the liquid film based on the average droplet size have indicated that the time between droplet impacts falling into a crater from a previous droplet is the shortest time scale, which will limit the amount of heat transfer that may take place during spray cooling. However, the observed time between large droplet impacts onto the same heater surface location is comparable to the computed time to heat and vaporize a large drop, indicating a new explanation for the onset of spray cooling CHF: localized dryout of the original large droplet impact craters.