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Coating Process (coating + process)
Selected AbstractsElastohydrodynamics of tensioned web roll coating processINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 6 2003M. S. Carvalho Abstract Coating process is an important step in the manufacturing of different products, such as paper, adhesive and magnetic tapes, photographic films, and many other. The tensioned web roll coating is one the several methods used by different industries. It relies on the elastohydrodynamic action between the fluid and the tensioned substrate for transferring and applying the liquid. The main advantage of this method is its ability to apply very thin liquid layers with less sensitivity to mechanical tolerance at relative small cost. Despite its industrial application, theoretical analysis and fundamental understanding of the process are limited. This work analyses this elastohydrodynamic action by solving the differential equations that govern the liquid flow, described by the Navier,Stokes equation, and the web deformation, modelled by the cylindrical shell approximation. The goal is to determine the operating conditions at which the process is two dimensional and defect free. The equations are discretized by the Galerkin/finite-element method. The resulting non-linear system of equations is solved by Newton's method coupled with pseudo-arc-length continuation in order to obtain solutions around turning points. The theoretical results are used to construct an operating window of the process that is in agreement with limited experimental data. Copyright © 2003 John Wiley & Sons, Ltd. [source] Ultrathin, Organic, Semiconductor/Polymer Blends by Scanning Corona-Discharge Coating for High-Performance Organic Thin-Film TransistorsADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Hee Joon Jung Abstract A new thin-film coating process, scanning corona-discharge coating (SCDC), to fabricate ultrathin tri-isopropylsilylethynyl pentacene (TIPS-PEN)/amorphous-polymer blend layers suitable for high-performance, bottom-gate, organic thin-film transistors (OTFTs) is described. The method is based on utilizing the electrodynamic flow of gas molecules that are corona-discharged at a sharp metallic tip under a high voltage and subsequently directed towards a bottom electrode. With the static movement of the bottom electrode, on which a blend solution of TIPS-PEN and an amorphous polymer is deposited, SCDC provides an efficient route to produce uniform blend films with thicknesses of less than one hundred nanometers, in which the TIPS-PEN and the amorphous polymer are vertically phase-separated into a bilayered structure with a single-crystalline nature of the TIPS-PEN. A bottom-gate field-effect transistor with a blend layer of TIPS-PEN/polystyrene (PS) (90/10 wt%) operated at ambient conditions, for example, indeed exhibits a highly reliable device performance with a field-effect mobility of approximately 0.23 cm2 V,1 s,1: two orders of magnitude greater than that of a spin-coated blend film. SCDC also turns out to be applicable to other amorphous polymers, such as poly(, -methyl styrene) and poly(methyl methacrylate) and, readily combined with the conventional transfer-printing technique, gives rise to micropatterned arrays of TIPS-PEN/polymer films. [source] Annealing-Free High Efficiency and Large Area Polymer Solar Cells Fabricated by a Roller Painting ProcessADVANCED FUNCTIONAL MATERIALS, Issue 14 2010Jae Woong Jung Abstract Polymer solar cells are fabricated by a novel solution coating process, roller painting. The roller-painted film , composed of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) , has a smoother surface than a spin-coated film. Since the roller painting is accompanied by shear and normal stresses and is also a slow drying process, the process effectively induces crystallization of P3HT and PCBM. Both crystalline P3HT and PCBM in the roller-painted active layer contribute to enhanced and balanced charge-carrier mobility. Consequently, the roller-painting process results in a higher power conversion efficiency (PCE) of 4.6%, as compared to that for spin coating (3.9%). Furthermore, annealing-free polymer solar cells (PSCs) with high PCE are fabricated by the roller painting process with the addition of a small amount of octanedi-1,8-thiol. Since the addition of octanedi-1,8-thiol induces phase separation between P3HT and PCBM and the roller-painting process induces crystallization of P3HT and PCBM, a PCE of roller-painted PSCs of up to 3.8% is achieved without post-annealing. A PCE of over 2.7% can also be achieved with 5,cm2 of active area without post-annealing. [source] Pore-Filling of Spiro-OMeTAD in Solid-State Dye Sensitized Solar Cells: Quantification, Mechanism, and Consequences for Device PerformanceADVANCED FUNCTIONAL MATERIALS, Issue 15 2009I-Kang Ding Abstract In this paper, the pore filling of spiro-OMeTAD (2,2,,7,7,-tetrakis-(N,N -di- p -methoxyphenylamine)9,9,-spirobifluorene) in mesoporous TiO2 films is quantified for the first time using XPS depth profiling and UV,Vis absorption spectroscopy. It is shown that spiro-OMeTAD can penetrate the entire depth of the film, and its concentration is constant throughout the film. We determine that in a 2.5-µm-thick film, the volume of the pores is 60,65% filled. The pores become less filled when thicker films are used. Such filling fraction is much higher than the solution concentration because the excess solution on top of the film can act as a reservoir during the spin coating process. Lastly, we demonstrate that by using a lower spin coating speed and higher spiro-OMeTAD solution concentration, we can increase the filling fraction and consequently the efficiency of the device. [source] Elastohydrodynamics of tensioned web roll coating processINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 6 2003M. S. Carvalho Abstract Coating process is an important step in the manufacturing of different products, such as paper, adhesive and magnetic tapes, photographic films, and many other. The tensioned web roll coating is one the several methods used by different industries. It relies on the elastohydrodynamic action between the fluid and the tensioned substrate for transferring and applying the liquid. The main advantage of this method is its ability to apply very thin liquid layers with less sensitivity to mechanical tolerance at relative small cost. Despite its industrial application, theoretical analysis and fundamental understanding of the process are limited. This work analyses this elastohydrodynamic action by solving the differential equations that govern the liquid flow, described by the Navier,Stokes equation, and the web deformation, modelled by the cylindrical shell approximation. The goal is to determine the operating conditions at which the process is two dimensional and defect free. The equations are discretized by the Galerkin/finite-element method. The resulting non-linear system of equations is solved by Newton's method coupled with pseudo-arc-length continuation in order to obtain solutions around turning points. The theoretical results are used to construct an operating window of the process that is in agreement with limited experimental data. Copyright © 2003 John Wiley & Sons, Ltd. [source] In-line analysis of a fluid bed pellet coating process using a combination of near infrared and Raman spectroscopyJOURNAL OF CHEMOMETRICS, Issue 7-8 2010Andrey Bogomolov Abstract Near infrared (NIR) and Raman spectroscopic analyzers applied through an immersion Lighthouse Probe (LHP) were used for simultaneous in-line monitoring of a fluid bed pellet coating process. Multivariate curve resolution analysis of data, collected from four pilot-scale batches, has shown that the two techniques deliver complementary information about the process and their combination may be synergistic. This data analysis enabled a much better understanding of some of the process observations and also gave some interesting insights into the best way to use the techniques themselves. PLS regression analysis of the product moisture and the quantity of coating material sprayed was performed using NIR and Raman data blocks both separately and in combination. The performance of method combination compared to individual techniques is analyzed and discussed. Copyright © 2010 John Wiley & Sons, Ltd. [source] Microencapsulation of Fish Oil by Spray Granulation and Fluid Bed Film CoatingJOURNAL OF FOOD SCIENCE, Issue 6 2010Sri Haryani Anwar Abstract:, The stability of microencapsulated fish oil prepared with 2 production processes, spray granulation (SG) and SG followed by film coating (SG-FC) using a fluid bed equipment, was investigated. In the 1st process, 3 types of fish oil used were based on the ratios of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (10/50, 33/22, and 18/12). Each type was emulsified with soluble soybean polysaccharide (SSPS) and maltodextrin to produce 25% oil powders. In the 2nd process, 15% film coating of hydroxypropyl betacyclodextrin (HPBCD) was applied to the granules from the 1st process. The powder stability against oxidation was examined by measurement of peroxide values (PV) and headspace propanal after storage at room temperature and at 3 to 4 °C for 6 wk. Uncoated powder containing the lowest concentration of PUFA (18/12) was found to be stable during storage at room temperature with maximum PV of 3.98 ± 0.001 meq/kg oil. The PV increased sharply for uncoated powder with higher concentration of omega-3 (in 33/22 and 10/50 fish oils) after 3 wk storage. The PVs were in agreement with the concentration of propanal, and these 2 parameters remained constant for most of the uncoated powders stored at low temperature. Unexpectedly, the outcomes showed that the coated powders had lower stability than uncoated powders as indicated by higher initial PVs; more hydroperoxides were detected as well as increasing propanal concentration. The investigation suggests that the film-coating by HPBCD ineffectively protected fish oil as the coating process might have induced further oxidation; however, SG is a good method for producing fish oil powder and to protect it from oxidation because of the "onion skin" structure of granules produced in this process. [source] Frequency response analysis of slot coatingAICHE JOURNAL, Issue 9 2010Takeaki Tsuda Abstract Frequency responses to the slot die coating process is analyzed using empirical modal analysis to predict the effects of periodic process disturbances such as gap oscillation and variations in vacuum pressure, web velocity, and flow rate. A type of empirical modal analysis known as an experimental modal approach was used, and an oscillator basis model was assumed by using a linearized governing equation, and the coefficient of the basis model was determined by curve-fitting. By completing the process, we were able to decompose each mode, during which process it was found that the modes are of two types: a squeeze mode related to viscous characteristics and sinuous modes that are identical to capillary waves. Observation of the meniscus shapes of each mode revealed, in the third mode near the lip edge, significant fluctuations that can induce other coating defects. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] MR-visible coatings for endovascular device visualizationJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2006Orhan Unal PhD Abstract Purpose To investigate the potential utility of magnetic resonance (MR)-visible coatings for passive visualization of therapeutic endovascular devices such as catheters and guidewires. Materials and Methods Using a multistep coating process, gadolinium-based coatings were applied to commercially available off-the-shelf catheters and guidewires. These coated devices were imaged in phantoms made of fat-free yogurt, saline, and whole blood and also in live canine aorta on a 1.5-T cardiovascular MR scanner using T1-weighted two-dimensional radiofrequency (RF)-spoiled gradient-recalled echo, two-dimensional spin echo, and three-dimensional RF-spoiled gradient-recalled echo techniques. Results Commercially available off-the shelf catheters (4, 5, and 6 French) and guidewires (0.038 inch) were clearly visualized in all phantoms and canine aorta and the coatings proved to be durable and imageable without degradation in signal intensity up to 24 hours. MR-visible coatings address some of the shortcomings that have previously limited the role of MR as a guidance tool. Conclusion Both in vitro and in vivo visualization of therapeutic endovascular devices coated with MR-visible coatings are found to be clinically viable. J. Magn. Reson. Imaging 2006. © 2006 Wiley-Liss, Inc. [source] Increasing process understanding by analyzing complex interactions in experimental dataJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 5 2009Kaisa Naelapää Abstract There is a recognized need for new approaches to understand unit operations with pharmaceutical relevance. A method for analyzing complex interactions in experimental data is introduced. Higher-order interactions do exist between process parameters, which complicate the interpretation of experimental results. In this study, experiments based on mixed factorial design of coating process were performed. Drug release was analyzed by traditional analysis of variance (ANOVA) and generalized multiplicative ANOVA (GEMANOVA). GEMANOVA modeling is introduced in this study as a new tool for increased understanding of a coating process. It was possible to model the response, that is, the amount of drug released, using both mentioned techniques. However, the ANOVA model was difficult to interpret as several interactions between process parameters existed. In contrast to ANOVA, GEMANOVA is especially suited for modeling complex interactions and making easily understandable models of these. GEMANOVA modeling allowed a simple visualization of the entire experimental space. Furthermore, information was obtained on how relative changes in the settings of process parameters influence the film quality and thereby drug release. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:1852,1861, 2009 [source] Approaches for the coating of capillary columns with highly phenylated stationary phases for high-temperature GCJOURNAL OF SEPARATION SCIENCE, JSS, Issue 4 2004Bernhard X. Mayer-Helm Abstract Two highly phenylated tetramethyl- p -silphenylene,diphenylsiloxane copolymers were coated on fused silica capillary columns and used as stationary phases in GC. The copolymers offered new insights into the coating process and column preparation due to their physicochemical properties. The fused silica capillary surface had to be pretreated in various ways to achieve a homogeneous film and a well deactivated surface: etching with ammonium bifluoride; leaching with sodium hydroxide and hydrochloric acid; silylation with tetraphenyldimethyldisilazane and triphenylsilylamine. Droplet formation was observed on tetraphenyldimethyldisilazane silylated surfaces leading to capillary columns with low separation efficiency. The topology of inhomogeneous films was investigated by light microscopy, scanning electron microscopy, and Auger electron spectroscopy. It became apparent that the stationary phase did not form droplets but islands, which are connected by a wetting layer according to the Stranski-Krastanov growth mode. Both copolymers are potential stationary phases for high-temperature GC with promising properties. They offer a higher overall polarity than 75% phenyl, 25% methyl-polysiloxanes in combination with increased thermal stability and reduced bleed levels. [source] Application of an Artificial Neural Network for Simulating Robust Plasma-Sprayed Zirconia CoatingsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2008Ming-Der Jean This article presents the application of the artificial neural network (ANN) of a statistically designed experiment for developing a robust wear-resistant zirconia coating. In this research, experimental design with orthogonal arrays efficiently provides enough information with the least number of experiments, reducing the cost and time. A radial basis function (RBF) network for the wear behavior is adopted. The friction and tribological properties of zirconia coatings were investigated. The microstructural feature of the coatings is also addressed in this study. It is found that the worn volumes of plasma-sprayed zirconia coatings after wear tests are greatly improved by the optimal parameters. The relationships between the microstructure of the worn surface and their properties are examined, and the results reveal a higher wear resistance and a lower worn surface roughness with a large amount of plastic deformations. These wear resistant structures formed as a result of a dense lamellar formation during sprayed zirconia coatings. The RBF network can be established efficiently. A comparison of the predicted results with that of the RBF network and the Taguchi method predictor shows average errors of 2.735% and 9.191% for the RBF network and the Taguchi method, respectively. It is experimentally confirmed that the RBF network predictions are in agreement with the experiments, and it can be reliably used for the prediction of wear for plasma sprayings. The experimental results demonstrate that the RBF network used for a statistically designed experiment is an effective, efficient, and intelligent approach for developing a robust, high efficiency, and high-quality zirconia coating process. [source] Effect of Slurry Rheological Properties on the Coating of Ceramic Honeycombs with Yttria-Stabilized-Zirconia WashcoatsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2000Christos Agrafiotis Recently, a novel automotive catalyst design, based on the use of palladium supported on yttria-stabilized zirconia (YSZ), was proposed. In the present work, the coating of cordierite honeycomb samples with YSZ slurries for the preparation of such washcoats was investigated. The loading percentage, homogeneity, and reproducibility were found to depend strongly on the slurry viscosity. Parameters such as the slurry-solids content, pH, type of powder used, and use and quantity of the dispersants were optimized for the preparation of stable, low-viscosity YSZ slurries, adjustments that could lead to an efficient coating process for honeycomb structures. [source] Corrosion of coating materials in oxidizing and hydrogen chloride containing atmospheresMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 12 2002S.C. Cha The boiler tubes in waste incinerator plants and power plants are mainly corrosive strained. This paper presents the corrosion behaviour of various coating materials in two corrosive atmospheres at 500°C. In a first test, Ni-based materials applied by High Velocity Oxygen Fuel Flame (HVOF)-spraying and Atmospheric Plasma Spraying (APS) as well as Cr-based materials obtained by diffusion coating process are tested in oxidizing atmosphere with water saturation. The results of the corrosion test in this H2O-O2 -N2 -atmosphere show that NiCr applied by HVOF is less oxidized than that applied by APS-coating, whereas NiCrBSi coating by APS shows higher resistance than that applied by HVOF-spraying. The diffusion coating of Cr/Si is better than that of pure Cr. In a second test, metallic Mo and W-based materials applied by thermal spraying are tested to verify their corrosion resistance in HCl-H2O-O2 -N2 -atmosphere. It is shown that pure Mo applied by APS on 13 CrMo 44 and WCrNi sprayed on 15 Mo 3 by HVOF as well as on 13 CrMo 44 show relatively high corrosion resistance, whereas Mo sprayed by APS on 15 Mo 3 is not resistant. Both tungsten-cobalt-chromium mixtures show extremely high oxidation rates. Base materials in both tests were the standard boiler tube materials 15 Mo 3 and 13 CrMo 44. But even the low corrosion rates of the best materials in these tests are higher compared to those of materials already presented by Cha et al. in an earlier paper. Korrosion von Beschichtungswerkstoffen in oxidierenden und chlorwasser-stoffhaltigen Atmosphären Die Wärmetauscherrohre von Müllverbrennungsanlagen und Kraftwerken sind hauptsächlich korrosiv beansprucht. Die vorliegende Veröffentlichung stellt das Korrosionsverhalten von verschiedenen Beschichtungswerkstoffen in zwei korrosiven Atmosphären bei einer Temperatur von 500°C vor. Zuerst wurden die durch Hochgeschwindigkeitsflammspritzen (HVOF) und atmosphärisches Plasmaspritzen (APS) aufgetragenen Ni-Basiswerkstoffe und die diffusionsbeschichteten Cr-Basiswerkstoffe in oxidierender Atmosphäre mit Wassersättigung getestet. Die Ergebnisse der Korrosionsversuche in der H2O-O2 -N2 -Atmosphäre zeigen, dass NiCr (HVOF) resistenter ist als durch APS Beschichtung, wobei die Beschichtung mit NiCrBSi durch APS höhere Beständigkeit als die durch HVOF zeigt. Eine diffusionsbeschichtete Cr/Si-Schicht zeigt höhere Beständigkeit als eine reine Cr-Schicht. In einer zweiten Versuchsreihe wurden metallisches Mo und W-Basiswerkstoffe auf Korrosionsbeständigkeit in HCl-H2O-O2 -N2 -Atmosphäre untersucht. Dabei zeigt sich, dass die Proben mit Mo (APS) auf 13 CrMo 44, sowie WCrNi (HVOF) auf 15 Mo 3 und 13 CrMo 44 relativ hohe Korrosionsbeständigkeiten besitzen. Dagegen ist Mo (APS) auf 15 Mo 3 nicht beständig. Beide W-Co-Verbindungen zeigen extrem hohe Oxidationsraten. Als Basiswerkstoffe wurden die Standard Kesselrohr-Werkstoffe 15 Mo 3 und 13 CrMo 44 gewählt. Aber auch die niedrigsten Korrosionsraten der besten Werkstoffe in dieser Untersuchung sind höher als diejenigen der in einer früheren Arbeit von Cha et al. vorgestellten Werkstoffe. [source] Design of optimal extrusion die for a range of different materialsPOLYMER ENGINEERING & SCIENCE, Issue 3 2009Nadhir Lebaal THE coat-hanger melt distributor is a device commonly used in the wire coating process. Its task is to distribute the melt around the conductor uniformly. It is quite common that materials and flow rates differ from what had been specified during the design procedure. This may lead to bad performance with materials of very different rheological properties from the design material. In this article, we present an optimal design approach to avoid this loss of performances. This approach involves coupling a three-dimensional finite element simulation software with an optimization strategy based on a response surface method. The objective is to determine a coat-hanger melt distributor geometry that ensures a homogeneous exit velocity distribution that will best accommodate for a different range of materials. A coat-hanger melt distributor with a manifold of constant width is designed, and a set of flow distribution measurements is established for two different materials. The results of numerical simulation are then validated by comparison with experimental measurements. The effect of material change is also investigated. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers [source] Effect of machine compliance on mold deflection during injection and packing of thermoplastic partsPOLYMER ENGINEERING & SCIENCE, Issue 7 2006Brian Carpenter Minimizing mold deflection is essential when manufacturing plastic parts to tight tolerances. Both the mold and the machine are compliant and deform upon loading, which can affect the part quality. Therefore, understanding mold deflection during injection molding is critical for determining the final geometry of the part. It is also critical for secondary processes such as the in-mold coating process. This article presents work in quantifying both mold deflection during an injection-molding cycle and the effect of machine compliance on mold behavior. The mold cavity pressure obtained using MoldFlowÔ was used as input for the subsequent finite element mold deflection analysis. Two different structural models were used: the first model included only the mold, the mold base units and the ejector platen; the second model included the effect of the injection-molding machine compliance. To validate the model, strain gage rosettes were placed on the mold and the machine. Validating experiments were conducted using process parameters identical to those used in the simulations. A comparison of the experimental and simulation results for both models is presented. POLYM. ENG. SCI., 46:844,852, 2006. © 2006 Society of Plastics Engineers [source] Numerical analysis of polymer melt flow in the nipping regionPOLYMER ENGINEERING & SCIENCE, Issue 4 2002M. Takase In the extrusion coating process, it has never been revealed how a polymer melt flows near the nipping region and how the cooling process occurs. We created a numerical simulation program for the polymer melt flow near the nipping region using the finite element method. Numerical results showed the effects of many individual factors (e.g. line speed, melt thickness, extrusion temperature, shear-thinning property, etc.) on the cooling process and polymer melt flow near the nipping region. It was found that a polymer melt buildup that can be observed between two calender rolls in the sheet forming process also formed in the extrusion coating process, and that the amount of polymer melt buildup (bank) depended upon the coating condition. It was found that not only line speed and melt thickness contribute to the extrusion coating process significantly, but also the rheological property has an effect on the process. [source] An Application of Six Sigma to Reduce WasteQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 6 2005Ricardo Bañuelas Abstract Six Sigma has been considered a powerful business strategy that employs a well-structured continuous improvement methodology to reduce process variability and drive out waste within the business processes using effective application of statistical tools and techniques. Although there is a wider acceptance of Six Sigma in many organizations today, there appears to be virtually no in-depth case study of Six Sigma in the existing literature. This involves how the Six Sigma methodology has been used, how Six Sigma tools and techniques have been applied and how the benefits have been generated. This paper presents a case study illustrating the effective use of Six Sigma to reduce waste in a coating process. It describes in detail how the project was selected and how the Six Sigma methodology was applied. It also shows how various tools and techniques within the Six Sigma methodology have been employed to achieve substantial financial benefits. Copyright © 2005 John Wiley & Sons, Ltd. [source] Effect of the Equipment Configuration and Operating Conditions on Process Performance and on Physical Characteristics of the Product During Coating in Spouted BedTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2004M. C. P. Publio Abstract The effects of the configuration and operating conditions on the performance of the spouted bed tablet coating process have been studied. The configuration parameters analyzed were the ratio between the draft tube diameter and the inlet orifice diameter, dT/di, and the conical base angle, ,. To analyze the equipment performance the adhesion coefficient, ,, and the increase rate of the tablet mass, K1, were measured as a function of the mass flow rate of the coating material, Ws, of the ratio between the mass feed flow rate of coating suspension relative to mass feed flow rate of the spouting gas, W*s/W*g, of the air flow rate relative to minimum spouting, Q/Qms, and of the feed flow rate of atomising air, Wat. Procedures for the evaluation of the growth kinetics and for measuring the product uniformity are presented. On a étudié les effets de la configuration et des conditions opératoires sur la performance du procédé d'enrobage de tablettes en lit jaillissant. Les paramètres de configuration étudiés sont le rapport entre le diamètre du tube d'aspiration et le diamètre de l'orifice d'entrée, dT/di, et l'angle de base conique, ,. Pour analyser la performance de l'équipement, le coefficient d'adhésion, ,, et la vitesse d'augmentation du poids de la tablette, K1, ont été mesurés en fonction du débit massique du matériau d'enrobage, Ws, du rapport entre le débit d'alimentation massique de la suspension d'enrobage et le débit d'alimentation massique du gaz jaillissant, W*s/W*g, du débit d'air et du jaillissement minimal, Q/Qms, et du débit d'alimentation de l'air d'atomisation, Wat. On présente des méthodes pour évaluer les cinétiques de croissance et mesurer l'uniformité de produit. [source] Hydrocolloid Coating of Xenopus laevis EmbryosBIOTECHNOLOGY PROGRESS, Issue 3 2000N. Kampf A novel technology for coating single cells and embryos with thin hydrocolloid (water-soluble polymer) films has been invented and patented. Coating is different from entrapment and immobilization in that the coating around the cell is thinner, comprising only a small fraction of the cell or embryo's diameter. Xenopus laevis embryos were coated with thin films of low-methoxy pectin (LMP), alginate, and ,- and ,-carrageenans. These gums have different compositions and structures and as such created different coatings around the fertilized cells. All coated embryos appeared to develop normally, similar to noncoated embryos. Elemental detection by ICP-AES spectroscopy revealed that the embryo can control the diffusion of excess ions to which it is exposed during the coating process. The coatings delayed hatching by 18,24 h. Consequently, at hatch the embryos were at a more developed stage than their noncoated counterparts. The hydrocolloid coating reduced the thickness of the natural jelly coating (JC). With the ,-carrageenan coating, percent hatch was maximal, while with LMP it was minimal, as a result of the films' mechanical properties and thicknesses. LMP and alginate created smoother coatings than the carrageenans. Potential interactions between the coating and the natural JC are hypothesized. Overall, coatings appear to be a suitable tool for laboratories interested in performing longer-term experiments with embryos. [source] The new easyFoam -Process and Mechanical Properties of Foam-Coating-SandwichesADVANCED ENGINEERING MATERIALS, Issue 11 2004M. Maurer Coated aluminium foams were heat treated. The influence on the mechanical properties was investigated. In order to produce cost-efficient foam sandwiches, the foaming and coating processes were modified and the new easyFoam -process was developed. It consists of coating foamable semi-finished parts before inductive foaming. This process allows a fast and continuous production of long foam sandwiches. No expensive moulds are needed. [source] Bioactive and mechanically strong Bioglass®-poly(D,L -lactic acid) composite coatings on surgical suturesJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2006Q. Z. Chen Abstract New coating processes have been investigated for degradable (Vicryl®) and nondegradable (Mersilk®) sutures with the aim to develop Bioglass® coated polymer fibers for wound healing and tissue engineering scaffold applications. First, the aqueous phase of a Bioglass® particle slurry was replaced with a poly(D,L -lactic acid) (PDLLA) polymer dissolved in solvent dimethyle carbonate (DMC) to act as third phase. SEM observations indicated that this alteration significantly improved the homogeneity of the coatings. Second, a new coating strategy involving two steps was developed: the sutures were first coated with a Bioglass®,PDLLA composite film followed by a second PDLLA coating. This two-step process of coating has addressed the problem of poor adherence of Bioglass® particles on suture surfaces. The coated sutures were knotted to determine qualitatively the mechanical integrity of the coatings. The results indicated that adhesion strength of coatings obtained by the two-step method was remarkably enhanced. A comparative assessment of the bioactivity of one-step and two-step produced coatings was carried out in vitro using acellular simulated body fluid (SBF) for up to 28 days. Coatings produced by the two-step process were found to have similar bioactivity as the one-step produced coatings. The novel Bioglass®/PDLLA/Vicryl® and Bioglass®/PDLLA/Mersilk® composite sutures are promising bioactive materials for wound healing and tissue engineering applications. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] Viscocapillary model of slide coating: Effect of operating parameters and range of validity,AICHE JOURNAL, Issue 10 2009K. Tjiptowidjojo Abstract Slide coating is one of the premetered high-precision coating methods. The layer thickness is set by the flow rate and web speed. The uniformity of the layer, however, can be affected by other operating conditions. Modeling the flow in the coating bead is necessary in developing the range of operability conditions where the layer is adequately uniform. Lubrication and viscocapillary models have been used to describe the flow and some of the operability limits of different coating processes. However, the available models of slide coating were developed with adhoc hypotheses that compromise their accuracy. We present a critical review of the available viscocapillary models and proposed changes to improve its range of applicability. The accuracy of the model is tested by comparing its predictions to the solution of the full two-dimensional Navier-Stokes equation. The model is valid at low capillary and Reynolds number regime and at low gap-to-wet thickness ratio. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Implant Surface Modification Using Laser Guided Coatings: In Vitro Comparison of Mechanical PropertiesJOURNAL OF PROSTHODONTICS, Issue 5 2008Asvin Vasanthan DDS Abstract Purpose: Plasma-sprayed hydroxyapatite (HA)-coated implants show failures along the coating,substrate interface due to poor bond strength. We analyzed HA coatings obtained by pulsed laser deposition (PLD) and compared them to commercially used plasma-sprayed coatings with respect to their bond strength to titanium alloy (Ti-6Al-4V), as well as surface roughness alterations produced by each of the two deposition methods. Materials and Methods: Twelve titanium alloy disks were plasma-sprayed under commercial implant coating conditions, and 24 titanium alloy disks were coated using PLD. All coatings were characterized by the presence of the different calcium phosphate (CaP) phases. The plasma-sprayed coatings (n = 12) were predominantly HA, and the pulsed laser-deposited coatings were hydroxydyapatite (n = 12) and HA coating with a tetra calcium phosphate (TTCP) phase (n = 12). The surface roughness was analyzed before and after the coating processes to assess roughness changes to the surface by the coatings. The adhesive bond strengths of these coatings to the substrate titanium alloy was tested and compared. Scheffé's test was used to analyze the statistical significance of the data. Results: The surface roughness alteration following PLD was a decrease of 0.2 ,m, whereas following plasma spraying the decrease was 1.0 ,m. Bond strengths were as follows [mean (SD) in MPa]: pulsed laser-deposited HA coatings: 68.3 (17.8); pulsed laser-deposited HA with tetra-CaP: 55.2 (21.1); plasma-sprayed HA 17.0 (2.8). The multivariate Scheffé's test revealed that HA coatings obtained by PLD had significantly increased bond strengths compared with the plasma sprayed ones (p, 0.05). Conclusions: HA coatings obtained by PLD showed greater adherence to titanium alloy. PLD offers an alternative method to produce thinner coatings with better adherence properties, along with precise control over the deposition process. [source] Preparation and characterization of microcapsulated red phosphorus and its flame-retardant mechanism in halogen-free flame retardant polyolefinsPOLYMER INTERNATIONAL, Issue 8 2003Qiang Wu Abstract Microcapsulated red phosphorus (MRP), with a melamine,formaldehyde resin coating layer, was prepared by two-step coating processes. The physical and chemical properties of MRP were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) and other measurements. The flame retardant action and mechanism of MRP in the halogen-free flame retardant (HFFR) polyolefins (PO) blends have been studied using cone calorimeter, limiting oxygen index (LOI), thermogravimetric analysis (TGA) and dynamic FTIR spectroscopy. The results show that the MRP, which is coated with melamine,formaldehyde resin, has a higher ignition point, a considerably lower amount of phosphine evolution and of water absorption compared with red phosphorus (RP) itself. The data observed by cone calorimeter, LOI and TGA measurements from the PO/HFFR blends demonstrated that the MRP can decrease the heat release rate and effective heat of combustion, and increase the thermostability and LOI values of PO materials. The dynamic FTIR results revealed the flame-retardant mechanism that RP can promote the formation of charred layers with the P,O and P,C complexes in the condensed phase during burning of polymer materials. 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