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1
Jiang, Chao. "Chemical reactions in can coating systems : their relevance to the coating characteristics and the performance of can coatings". Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496545.
Testo completo
2
Abu-ali, Jareer. "Food coating application in: electrostatic atomization, non-electrostatic coating and electrostatic powder coating". The Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1092539703.
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3
Abu-ali, Jareer Mansour. "Food coating application in: electrostatic atomization, non-electrostatic coating and electrostatic powder coating /". Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1092539703.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xii, 196 p.; also includes graphics (some col.). Includes bibliographical references (p. 185-192). Available online via OhioLINK's ETD Center
4
Adegbite, Stephen Ademola. "Coating of catalyst supports : links between slurry characteristics, coating process and final coating quality". Thesis, University of Birmingham, 2010. http://etheses.bham.ac.uk//id/eprint/920/.
Testo completoAbstract (sommario):
Tightening legislation for vehicles across the world has caused the use of monolith catalysts in automotive emission control to become ubiquitous. Control of the adherence and homogeneity of the platinum group metal (PGM) coating onto the monolith block, to maximise catalytic performance for a minimum PGM loading, is therefore paramount. In this study, an automatic film application is used for coating γ–alumina slurries onto Fecralloy®, an integral component of metallic monolith catalysts, to achieve the desired coating properties. Upon coating of the Fecralloy® coupons, the samples preoxidised for 10 h gave the best performance in terms of coating loading (7.94 mass %) and adherence (< 10 mass % loss) based on ultrasonic vibration test. These conditions produced the optimal surface topography, typified by conspicuous and randomly-oriented α–alumina whiskers which promote coating adherence. The optimal coating loading and adherence were achieved at a pH of 4 and solids concentrations not exceeding 40 wt%. A newly devised technique using the electromechanical testing system showed that finest particle coatings of 40 wt% solids concentration produced the best coating adherence. At solids concentration of 45 wt% the coating adherence was poor and insensitive to the blends of different particle size distributions.
5
Prall, Katharina. "The Viscoelastic Behavior of Pigmented Latex Coating Films". Fogler Library, University of Maine, 2000. http://www.library.umaine.edu/theses/pdf/PrallK2000.pdf.
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6
Kashefi, Mehrdad. "PRIME surface coating : a novel method for making thick ceramic coatings". Thesis, Nottingham Trent University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431899.
Testo completo
7
Jain, Rahul. "Investigations on Multiscale Fractal-textured Superhydrophobic and Solar Selective Coatings". Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78725.
Testo completoAbstract (sommario):
Functional coatings produced using scalable and cost-effective processes such as electrodeposition and etching lead to the creation of random roughness at multiple length scales on the surface. The first part of thesis work aims at developing a fundamental mathematical understanding of multiscale coatings by presenting a fractal model to describe wettability on such surfaces. These surfaces are described with a fractal asperity model based on the Weierstrass-Mandelbrot function. Using this description, a model is presented to evaluate the apparent contact angle in different wetting regimes. Experimental validation of the model predictions is presented on various hydrophobic and superhydrophobic surfaces generated on several materials under different processing conditions.
Superhydrophobic surfaces have myriad industrial applications, yet their practical utilization has been severely limited by their poor mechanical durability and longevity. Toward addressing this gap, the second and third parts of this thesis work present low cost, facile processes to fabricate superhydrophobic copper and zinc-based coatings via electrodeposition. Additionally, systematic studies are presented on coatings fabricated under different processing conditions to demonstrate excellent durability, mechanical and underwater stability, and corrosion resistance. The presented processes can be scaled to larger, durable coatings with controllable wettability for diverse applications.
Apart from their use as superhydrophobic surfaces, the application of multiscale coatings in photo-thermal conversion systems as solar selective coatings is explored in the final part of this thesis. The effects of scale-independent fractal parameters of the coating surfaces and heat treatment are systematically explored with respect to their optical properties of absorptance, emittance, and figure of merit (FOM).Master of Science
8
Cakar, Ilknur. "Conductive Coating Materials". Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/2/12607410/index.pdf.
Testo completoAbstract (sommario):
In this study, electrically conductive coating materials composed of epoxy resin and carbon black (CB) were prepared by applying two different mixing techniques (Grinding and Mechanical Mixing). The effect of carbon black addition, ultrasonication, mixing type and surface modification of carbon black on the morphologies, electrical and mechanical properties of the composites were investigated.
According to test results, Grinding Method is much more efficient and for this method, percolation concentration was found as 2 vol %. The electrical resistivity value obtained at this composition is around 107 ohm.cm. Also, for the samples prepared by Grinding Method, the hardness increased by adding conductive filler, but the impact energy and adhesive strength decreased with increasing carbon black content.
Ultrasonication was applied to the samples containing 2 vol % CB obtained by Grinding Method to reduce the electrical resistivity further. Three different ultrasonic mixing times were tried, however, no positive effect was observed on electrical and mechanical properties.
Since the addition of carbon black has a negative effect on the processability of the mixture, it was aimed to obtain desired conductivity value at lower percolation concentration by modifying carbon black surface with different silane coupling agents and formamide. The best result in terms of electrical conductivity was obtained for the materials produced with formamide treated carbon black by Grinding Method. At 1 vol % concentration, the electrical resistivity was found as approximately 106 ohm.cm which is three orders smaller than the resistivity of materials prepared with untreated carbon black.
9
Andrea, Bergqvist. "Coating fine particles". Thesis, Uppsala universitet, Institutionen för kemi - Ångström, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-235233.
Testo completoAbstract (sommario):
Controlled release of an active is used in many applications. An example is drug delivery were it is desirable to release the active substance close to the target. In paints can anti-mold substances be encapsulated and released slowly during a long time which can extend the lifetime of the paint. This work investigated a coating process of loaded particles with as low leakage of the active substance as possible. It was also studied if the coating process was scalable. The particles in use were porous silica that was coated with sodium dodecyl sulphate (SDS), polyethyleneimine (PEI) and tetraethyl orthosilicate (TEOS). To fill particles, the active was dissolved in a solution and the particles were added. The active adsorbed into the pores of the particle. The coating principle was about the same for all layers. The coating molecules were dissolved in a solvent and the particles were added during stirring. After centrifugation the coated particles were separated from the solvent and left to dry. The thermogravimetric analyzer (TGA) was used to calculate the amount of adsorbed polymers on the particle surface. UV/VIS spectrometer analyzed the release rate of the active. As the recipe was optimized, SDS could be excluded from the process. An adsorption isotherm for PEI on the particle surface showed that 0.5 g PEI/ g particle the ratio required for covering the surface completely. It was proved that if the active was dissolved in all coating solutions during the coating, less leakage appear and makes the coating process more controlled. A higher amount of both PEI and TEOS improves the encapsulation of the active, which reduces the release rate. The coating process is proved to be scalable as the particle concentration is increased from 4.72 % to 16.5 % without too much agglomeration.
10
ZIPPERIAN, DONALD CHARLES. "PHYSICAL AND CHEMICAL CHARACTERISTICS OF THE ZINCATE IMMERSION PROCESS FOR ALUMINUM AND ALUMINUM ALLOYS". Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184123.
Testo completoAbstract (sommario):
A detailed experimental study has been carried out to investigate the zincate immersion deposition process for 99.99%, 6061, and 356-T6 aluminum samples. In particular, the effect of iron and tartrate in the immersion bath, the aluminum surface preparation, and the relationship of the first immersion step to the second immersion step were investigated by chemical, electrochemical (polarization and rest potentials), and surface analytical scanning electron microscopy (SEM), transmission electron microscopy (TEM), Rutherford backscattering spectrometry (RBS), X-ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy (AES) techniques. Eh-pH diagrams were constructed to determine the most stable zinc, iron, and aluminum species in solution. These diagrams predict that ferrous and ferric ions, as well as aluminum should form stable complexes with tartrate at the typical immersion deposition conditions (Eh -0.9 to -1.0 and pH 14 to 15). Experimentally, tartrate was found to enhance the dissolution rate of aluminum in highly caustic solutions. The addition of ferric chloride to the immersion bath produced coatings that were more crystalline, and also decreased the amount of hydrogen gas evolved in the second immersion step. The deposition of zinc and iron during the second immersion step was considerably less than that during the first immersion step. The second immersion coating became more adherent as the initial surface roughness decreased, and as grain size was increased the second immersion coating became thicker. For increasing grain size the micrographs for the first and second immersion coatings showed that the coatings became more localized. The second immersion coating thickness and morphology were also dependent upon several first immersion variables, such as bath temperature, immersion time and bath composition. Increased dissolution rates of aluminum in the first immersion produced thinner coatings with a finer crystallite growth. Increased bath temperature and increased first immersion time enhanced the dissolution rate of aluminum. The zinc coating slowed the dissolution rate of aluminum. When zinc was absent from the first immersion bath, the aluminum dissolution was much faster and resulted in thinner coatings upon subsequent second immersion. The molar ratio of zinc deposited to aluminum dissolved was a constant value of 1.1 for both first and second immersions; the molar ratio was also constant for the different aluminum substrates examined in this investigation.
11
Pandey, Preetanshu. "Studies to investigate variables affecting coating uniformity in a pan coating device". Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4469.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--West Virginia University, 2006.Title from document title page. Document formatted into pages; contains xiv, 122 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 107-116).
12
Mahmud, Gazi Arif. "Increasing the coating resistance against UV degradation and corrosion using nanocomposite coating". Thesis, Wichita State University, 2009. http://hdl.handle.net/10057/2523.
Testo completoAbstract (sommario):
In this research project, a nanocomposite coating was developed using multiwall carbon
nanotubes (MWCNT) associated with epoxy primer in order to increase coating resistance
against ultra-violet radiation and corrosion. The effectiveness of this nanocomposite coating was
evaluated by exposing it to ultra-violet light for different time period. To determine
hydrophilic/hydrophobic characteristics of the different UV exposed coated surface, the water
contact angle was measured on the surfaces. The UV degraded samples were also exposed to the
salt fog corrosion chamber for 80 days.
The coating performance tests were carried out using digital images, optical microscope,
atomic force microscope (AFM) and thickness measurement. It was found that the addition of
multiwall carbon nanotubes into the coating materials drastically increased the coating resistance
against ultra-violet radiation and corrosion. Overall, this coating can be an option to solve the
problem of the UV degradation and corrosion of metals and composites.Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering
13
PEREZ, EDUARDO DE BRITTO. "SLOT COATING PROCESS: EFFECT OF GAP OSCILLATION ON THE COATING THICKNESS UNIFORMITY". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2009. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=14886@1.
Testo completoAbstract (sommario):
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
O processo de revestimento por extrusão (slot coating) é muito utilizado em produtos que requerem alta uniformidade de espessura. Sua janela de operação em regime permanente já foi plenamente estudada, mas o entendimento completo do processo requer a análise da sua sensibilidade a pequenas variações nos parâmetros operacionais. Neste trabalho é feita uma análise transiente (por simulação numérica) do efeito de uma variação periódica conhecida da fresta de revestimento na uniformidade da espessura do líquido revestido. Várias geometrias de barras de revestimento e parâmetros de processo são testados e os respectivos fatores de amplificação determinados em função da frequência de oscilação da fresta de revestimento. O ajuste inicial da fresta e o nível de vácuo aplicado a montante da barra de revestimento são duas variáveis básicas de processo, pois podem ser rapidamente ajustadas. Gráficos de contorno do fator de amplificação no espaço da fresta de revestimento contra o nível de vácuo são mostrados e surgem conclusões interessantes sobre a condição ótima de ajuste para minimização do fator de amplificação. Um algoritmo de otimização é utilizado com o objetivo de determinar pontos de mínimo no campo do fator de amplificação no espaço da fresta de revestimento contra o nível de vácuo. O líquido é considerado Newtoniano a as simulações são feitas a baixos números de capilaridade e Reynolds.
Slot coating is one of the preferred methods when high precision is required and several studies focusing on its steady state analysis were made to determine the operating window of the process. However, full understanding of coating flows requires not only the two-dimensional, steady state solution of the governing equations, but also the sensitivity of those flows to small upsets. An effort to understand the impact of the coating gap periodic oscillation on down web thickness variation is made using computer aided simulation. Different slot die lip geometries and process conditions are tested and the respective amplification factors as a function of gap oscillation frequencies are reported. Coating gap and the vacuum level are particulary important process variables because are easily changed by the process engineer. Two dimensional contour plots of the amplification factor in the space of coating gap against vacuum level are reported for some geometries, and interesting results show up about their optimal adjusts. In the last chapter an optimization algorithm is used to find minimum values of the amplification factor of gap oscillation in the space of coating gap against vacuum level. The liquid is assumed Newtonian and computations are made at low capillary (up to 1.6) and Reynolds numbers. The transient free surface flow with appropriate boundary conditions is solved by the Galerkin/finite element methods, with time integration by a predictor-corrector algorithm. The set of non-linear algebraic equations for the finite element basis functions coefficients is solved by Newton’s method.
14
Pallay, Krista Joy. "Surface Modifications to Mitigate Refractory Degradation in High-Temperature Black Liquor Gasifiers". Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10488.
Testo completoAbstract (sommario):
Ceria (CeO2), chromia (Cr2O3), yttria-stabilized zirconia (Y2O3-ZrO2), and sodium cerium oxide (Na2CeO3) were used as barrier coatings on Ufala, an alumina-based ceramic refractory, to determine if they were effective at increasing the life of the refractory in a high-temperature black liquor gasification environment. The ceria, chromia, and yttria-stabilized zirconia coatings were applied at atmospheric pressure using a coating applicator at the Institute of Paper Science and Technology at the Georgia Institute of Technology. The sodium cerium oxide coatings in addition to the three other coating types were applied under atmospheric pressure at C3 International Technologies in Alpharetta, GA. The coated refractory, as well as a set of uncoated refractory used for baseline analysis, were tested using molten synthetic smelt at 1000C for 36 hours. Uncoated refractory samples were also tested for 12, 72, 120, and 168 hours in order to make a kinetic reaction rate determination. The refractory were analyzed using gravimetric and dimensional analysis, X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy to determine the severity of the physical changes that occurred after exposure to molten smelt. The data gathered from these experiments were not able to conclude that barrier coatings are sufficient to impede corrosion of the Ufala refractory material in molten smelt.
15
Antonellini, Vincent. "Le Facce del Coating". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2016.
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16
Gidlöf, Zandra. "Coating of bioceramic microneedles". Thesis, Umeå universitet, Farmakologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-119007.
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17
Johnson, Mitchell A. "Viscoelastic Roll Coating Flows". Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/JohnsonMA2003.pdf.
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Hadjialirezaei, Soosan. "Coating of alginate capsules". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bioteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-22908.
Testo completoAbstract (sommario):
Alginate is a popular candidate for encapsulation of cells due to the formation of gels with divalent ions under physiological conditions. Stable alginate gels can be formed by the selection of alginates with a high content of guluronic acid (G) and gelling in a mixture of calcium and barium. These alginate gels have been proposed as immune protective barriers for the transplantation of human pancreatic islets (insulin producing cells) for the treatment of type 1 diabetes where the alginate gel protects the transplant from the host immune system. Microencapsulation can thus provide a way to overcome the need for immunosuppressive drugs. Although showing promising results in animal models, there are potential limitations of the Ca2+/Ba2+-beads concerning growth of host cells on the surface of capsules in primate models. Development of coating strategies for alginate based capsules could thus be beneficial for reducing the attachment of host cells. Alginate microbeads/capsules were formed by electrostatic bead generator producing beads of 400µm. Afterward, the alginate beads were coated by fluoresceinamine labeled alginate that was visualized by confocal laser scanning microscopy (CLSM) and quantified by fluorescent spectroscopy. The binding of coating alginate to alginate-poly-L-lysine (PLL) capsules was also studied.In this project, in the optimalisation of coating of alginate beads some parameters were studies such as concentration of coating alginate, different gelling ions both for core and coating alginate, exposure time for gelling solution for fixation of coating layer and different washing solution.The long-term stability of coating layer of coated alginate beads was determined by measuring the fluorescent intensity of fluorescently labeled of coating alginate during a period of forty nine days. A stability study of alginate-alginate capsules revealed that Ca2+/Ba2+ alginate coated with high-G alginate and washed with saline and used Ca2+ and Ba2+ with ratio 50:1 for fixation of coating layer were more stable coating than other capsules. The alginate beads coated with high-M or epimerized alginate were produced. It shows higher intensity of coating layer in both capsules coated with high-M or epimerized alginate than alginate beads coated with high-G alginate. In continue of the study, the alginate-PLL capsules were coated with high-G, high-M, and epimerized and sulfated alginate. Alginate-PLL capsules coated with high-G, high-M and epimerized alginate shows no detective signal by confocal images and sulfated alginate coating shows some signal of coating. The stability of coating for alginate-PLL-alginate capsules and alginate beads coated with epimerized or high-M alginate revealed that both kind of coating have high-stability over one week screening.Three dimensional images of capsules, in confocal microscope, both epimerized and high-M coating alginates cover whole of capsules. However, in 3D images we have seen some fragment of coating gelling in the surround solution and attached to the capsules which can make disturbance in spectroscopy measurement. 3D images of alginate-PLL capsules coated with sulfated alginate show evenly distribution of coating.
19
Pollitt, Michael John. "Protein coating of nanoparticles". Thesis, University College London (University of London), 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442065.
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Moolman, Pieter Lafras. "Rheology of coating systems". Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53577.
Testo completoAbstract (sommario):
Thesis (MScEng)--Stellenbosch University, 2003.ENGLISH ABSTRACT: Desired behaviour of paint during processing, storage, application and after application is of great importance in the coatings industry. Rheology (the study of flow and deformation behaviour) is used as a method to investigate the behaviour of the flow and deformation properties of the paint during these stages. Some of the more important phenomena that can occur during these stages, which were examined rheologically, are: 1. The rheological behaviour of certain complex raw materials during processing - vesiculated beads suspensions 11. The paint behaviour during storage - in-can stability, e.g. phase separation and sedimentation of particles; Ill. The paint during application - ease of application, spatter, etc.; IV. The paint behaviour after application - sag, layer thickness, levelling (ability to hide brush marks), etc. A rheometer was used to obtain rheological curves from a paint sample (± 1 ml). Correct interpretation of these curves, which display rheological properties of the sample such as the viscosity, shear stress, structural strength and many more, produced information about the properties mentioned in i, ii, iii and iv above. It was found that the rheological data correlated well with empirical tests carried out in the laboratory for spatter, sag, levelling behaviour and in-can stability of the paint. A wide variety of paints were studied ranging from tough/durable outdoor paints to smooth/velvety indoor paints. The rheological behaviour explained the specific end-use properties of the paints. Paints from two different companies were compared on a rheological basis. In some cases large differences in rheological behaviour were observed. Rheology modifiers were tested on a new paint. It was found that specific rheology modifiers could be incorporated into the formulation to give the specific rheological behaviour required. Rheological modelling was performed and it was found that the flow behaviour of paint cou1d be modelled accurately with existing viscosity models (Ostwald/de Waal, Bingham, Casson, Herschel-Bulkley, Cross and Philips-Deutsch). Other rheological properties of paint were also modelled successfully with a simple linear regression model. Rheology was also used as a method to examine the flow and deformation properties of vesiculated beads, a component of paint with very complex rheology. The most important factors that influence the rheological behaviour of the vesiculated beads were determined. It was found that the type of manufacturing process for the beads affected the rheological behaviour. The effect of the raw materials used to manufacture the vesiculated beads were rheologically determined.
AFRIKAANSE OPSOMMING: Dit is baie belangrik dat verf die gewenste gedrag moet toon tydens berging, vervaardiging, tydens aanwending en direk na aanwending. Reologie (die studie van vloei- en vervorming) word gebruik as a metode om die vloei- en vervormingseienskappe van verf gedurende bogenoemde stadia te ondersoek. Sommige van die belangriker verskynsels wat gedurende hierdie stadia kan plaasvind, is d.m.v reologiese toetse ondersoek. Die verskynsels is as volg: i. Die reologiese gedrag van komplekse grondstowwe soos gevesikuleerde partikel suspensies. ll. Verfgedrag tydens berging - stabiliteit van verf in die blik, bv. faseskeiding en sedimentasie van partikels lll. Verfgedrag tydens aanwending - gemak van aanwending, spatsels IV. Verfgedrag direk na aanwending - afsakking, dikte van verflaag, vloei-eienskappe 'n Reometer is gebruik om die reologiese kurwes te bepaal deur gebruik te maak van ± 1 ml monster. Korrekte interpretasie van hierdie kurwes, wat onder meer eienskappe soos viskositeit, spanning en struktuursterkte insluit, lei tot inligting wat die verskynsels in i, ii, iii en iv kan verklaar. Daar is gevind dat inligting wat verkry is i.v.m die verskynsel van spatsels, afsakking, vloei en die stabiliteit van verf in die blik, goed korreleer met empiriese toetse wat in die laboratorium uitgevoer is. 'n Groot verskeidenheid van verwe, wat wissel van duursame/sterk buitemuurse verf, tot fluweelsagte binnenshuise verf, isondersoek. Die reologiese toetse het daarin geslaag om die eienskappe van die eindproduk suksesvol te verduidelik. Verf van twee verskillende maatskappye is ook met mekaar vergelyk op 'n reologiese grondslag. Daar is by sommige van die verwe aansienlike verskille in die reologiese gedrag gevind. 'n Nuwe verf is gebruik om die uitwerking van reologie modifiseerders te ondersoek. Daar is gevind dat daar spesifieke reologie modifiseerders bestaan wat unieke reologiese gedrag verseker. Reologiese modellering is gedoen op verf en daar is gevind dat die vloeigedrag van die verf akkuraat gemodelleer kan word deur van die bestaande viskositeitsmodelle gebruik te maak (Ostwald/de Waal, Bingham, Casson, Herschel- Bulkley, Cross en Philips-Deutsch). Ander reologiese eienskappe is gemodelleer deur gebruik te maak van eenvoudige regressie modelle. Daar is ook van reologiese tegnieke gebruik gemaak om die vloei en vervormingseienskappe van gesuspendeerde gevesikuleerde partikels, wat as 'n grondstof vir verf gebruik word, te ondersoek. Die belangrikste faktore wat die reologiese gedrag beïnvloed het, was onder meer die verskillende prosesse waarmee die gevesikuleerde partikels vervaardig is. Die effek van sekere van die grondstowwe wat gebruik word om die gevesikuleerde partikels te vervaardig, is ook reologies ondersoek.
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Sobani, Masoud. "Smart Flexible Anticorrosion Coating". University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1541778536930059.
Testo completo
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Kuni, Stefan. "The effect of board coating and precalendering on coating coverage and surface structure /". Åbo : Laboratory of paper chemistry, faculty of chemical engineering, Åbo Akademi university, 2003. http://catalogue.bnf.fr/ark:/12148/cb409218911.
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Brown, Robert W. "Development of a Novel Grease Resistant Functional Coatings for Paper-based Packaging and Assessment of Application by Flexographic Press". Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc4554/.
Testo completoAbstract (sommario):
Recent commercial developments have created a need for alternative materials and methods for imparting oil/grease resistance to paper and/or paperboard used in packaging. The performance of a novel grease resistant functional coating comprised of polyvinyl alcohol (PVA), sodium tetraborate pentahydrate (borate) and acetonedicarboxylic acid (ACDA) and the application of said coating by means of flexographic press is presented herein. Application criteria is developed, testing procedures described, and performance assessment of the developed coating materials are made. SEM images along with contact angle data suggest that coating performance is probably attributable to decreased mean pore size in conjunction with a slightly increased surface contact angle facilitated by crosslinking of PVA molecules by both borate ions and ACDA.
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Beresnev, V. M., O. V. Sobol’, Олександр Дмитрович Погребняк, Александр Дмитриевич Погребняк, Oleksandr Dmytrovych Pohrebniak, U. S. Nyemchenko, S. S. Grankin et al. "About Peculiarities of the Influence of the Negative Bias Potential Applied to the Substrate During the Deposition Process on the Structural State and Properties of the Multilayer system MoN-CrN". Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/42799.
Testo completoAbstract (sommario):
Applying transition metal nitrides of Mo and Cr, which are characterized by a relatively low heat of formation, as the components of the multilayer coating, the possibilities of elemental and structural engineering of vacuum-arc coatings under the influence of the bias potential Us and the reaction gas pressure PN are revealed. It was found that at a relatively small thickness of the layers of nanometer range, which provides superhard state of the coatings, the supply of Us with the value of above the critical leads to a drop in hardness, which can be explained by mixing of layers at the interphase boundary.
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Bouscher, Robert F. "Advancements in Powder Coating Processing and in Real-time Film Formation Analysis of Thermoset Coatings". University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1627566578541715.
Testo completo
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Derksen, James Stephen. "A new coating method for semiconductor lithography : fluid layer overlap in extrusion-spin coating". Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43575.
Testo completo
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Fonner, Adam M. "An Investigation on Syndiotactic Polystyrene Aerogel Coating of Macroporous Fabric via Dip Coating Method". University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron15550203400871.
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Mahfoudhi, Marouen. "Numerical optimisation of electron beam physical vapor deposition coatings for arbitrarily shaped surfaces". Thesis, Cape Peninsula University of Technology, 2015. http://hdl.handle.net/20.500.11838/2225.
Testo completoAbstract (sommario):
Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology.For the last few decades, methods to improve the engine efficiency and reduce the fuel consumption of jet engines have received increased attention. One of the solutions is to increase the operating temperature in order to increase the exhaust gas temperature, resulting in an increased engine power. However, this approach can be degrading for some engine parts such as turbine blades, which are required to operate in a very hostile environment (at ≈ 90% of their melting point temperature). Thus, an additional treatment must be carried out to protect these parts from corrosion, oxidation and erosion, as well as to maintain the substrate’s mechanical properties which can be modified by the high temperatures to which these parts are exposed. Coating, as the most known protection method, has been used for the last few decades to protect aircraft engine parts. According to Wolfe and Co-workers [1], 75% of all engine components are now coated. The most promising studies show that the thermal barrier coating (TBC) is the best adapted coating system for these high temperature applications. TBC is defined as a fine layer of material (generally ceramic or metallic material or both) directly deposited on the surface of the part In order to create a separation between the substrate and the environment to reduce the effect of the temperature aggression. However, the application of TBCs on surfaces of components presents a challenge in terms of the consistency of the thickness of the layer. This is due to the nature of the processes used to apply these coatings. It has been found that variations in the coating thickness can affect the thermodynamic performance of turbine blades as well as lead to premature damage due to higher thermal gradients in certain sections of the blade. Thus, it is necessary to optimise the thickness distribution of the coating.
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Olsson, Robert. "Some aspects on flexographic ink-paper and paperboard coating interaction". Doctoral thesis, Karlstad : Faculty of Technology and Science, Chemical Engineering, Karlstad University, 2007. http://www.diva-portal.org/kau/abstract.xsql?dbid=1218.
Testo completo
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Dahlström, Christina. "Quantitative microscopy of coating uniformity". Doctoral thesis, Mittuniversitetet, Institutionen för tillämpad naturvetenskap och design, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-16454.
Testo completoAbstract (sommario):
Print quality demands for coated papers are steadily growing, and achieving coating uniformity is crucial for high image sharpness, colour fidelity, and print uniformity. Coating uniformity may be divided into two scales: coating thickness uniformity and coating microstructure uniformity, the latter of which includes pigment, pore and binder distributions within the coating layer. This thesis concerns the investigation of both types of coating uniformity by using an approach of quantitative microscopy.First, coating thickness uniformity was analysed by using scanning electron microscope (SEM) images of paper cross sections, and the relationships between local coating thickness variations and the variations of underlying base sheet structures were determined. Special attention was given to the effect of length scales on the coating thickness vs. base sheet structure relationships.The experimental results showed that coating thickness had a strong correlation with surface height (profile) of base sheet at a small length scale. However, at a large length scale, it was mass density of base sheet (formation) that had the strongest correlation with coating thickness. This result explains well the discrepancies found in the literature for the relationship between coating thickness variation and base sheet structure variations. The total variance of coating thickness, however, was dominated by the surface height variation in the small scale, which explained around 50% of the variation. Autocorrelation analyses were further performed for the same data set. The autocorrelation functions showed a close resemblance of the one for a random shot process with a correlation length in the order of fibre width. All these results suggest that coating thickness variations are the result of random deposition of particles with the correlation length determined by the base sheet surface textures, such as fibre width.In order to obtain fundamental understandings of the random deposition processes on a rough surface, such as in paper, a generic particle deposition model was developed, and systematic analyses were performed for the effects of particle size, coat weight (average number of particles), levelling, and system size on coating thickness variation. The results showed that coating thickness variation3grows with coat weight, but beyond a certain coat weight, it reaches a plateau value. A scaling analysis yielded a universal relationship between coating thickness variation and the above mentioned variables. The correlation length of coating thickness was found to be determined by average coat weight and the state of underlying surfaces. For a rough surface at relatively low coat weight, the correlation length was typically in the range of fibre width, as was also observed experimentally.Non-uniformities within the coating layer, such as porosity variations and binder distributions, are investigated by using a newly developed method: field emission scanning electron microscopy (FESEM) in combination with argon ion beam milling technique. The combination of these two techniques produced extremely high quality images with very few artefacts, which are particularly suited for quantitative analyses of coating structures. A new evaluation method was also developed by using marker-controlled watershed segmentation (MCWS) of the secondary electron images (SEI).The high resolution imaging revealed that binder enrichment, a long disputed subject in the area, is present in a thin layer of a 500 nm thickness both at the coating surface and at the base sheet/coating interface. It was also found that the binders almost exclusively fill up the small pores, whereas the larger pores are mainly empty or depleted of binder.
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Dutheillet, Lamonthezie Yves. "Barrier properties of epoxy coating". Thesis, Brunel University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445939.
Testo completo
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Shin, Jae Young. "The Leveling of Coating Layers". Fogler Library, University of Maine, 2004. http://www.library.umaine.edu/theses/pdf/ShinJY2004.pdf.
Testo completo
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Dyson, Rosemary. "Mathematical Modelling of Curtain Coating". Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489434.
Testo completo
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Jenkins, Andrew Tobias Aveling. "Electrochemical studies of coating degradation". Thesis, University of Newcastle Upon Tyne, 1995. http://hdl.handle.net/10443/967.
Testo completoAbstract (sommario):
The polymer coatings considered in this thesis work principally by creating a barrier, in order to prevent a corroding medium such as water and / or oxygen from contacting the surface of the underlying metal. Such coatings are subject to attack from the environment in which they are placed. This attack can lead to failure of the coating and corrosion of the underlying metal. In this thesis, three principle means of coating degradation, leading to subsequent corrosion of the substrate have been considered: Mechanical damage of the coating, the effect of ultra-violet light weathering and filiform corrosion. Electrochemical measurements have been made in order to attempt to quantify both the degree of coating breakdown and the extent of corrosion of the substrate. The principle method for measuring coating breakdown and substrate corrosion utilised in the work for this thesis was Electrochemical Impedance Spectroscopy (EIS). EIS, in principle, allows both changes in coating porosity resulting from coating breakdown, and the extent of corrosion of the substrate to be measured. The extent of delamination under polymer coatings on defects of different sizes and on different substrates has been measured. The effect of ultra-violet light weathering of polymer coatings was measured using EIS and correlated with measurements of light reflection of the coating. Filiform corrosion was induced on two different substrates, coated with various coatings. The effect of substrate and coating on filiform corrosion growth rate and mechanism has been considered.
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QUINONES, DANMER PAULINO MAZA. "COATING PROCESS OF PHOTOSENSITIVE CYLINDERS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2009. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=15376@1.
Testo completoAbstract (sommario):
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Cilindros fotossensíveis são usados nos processos de impressão e particularmente na impressão eletrofotográfica. O revestimento é aplicado ao cilindro em forma líquida antes de solidificar-se. O líquido é aplicado ao cilindro através de um aplicador de agulha que se translada ao longo da direção axial do cilindro. Durante este processo o cilindro gira em torno de seu próprio eixo levando a uma deposição da tira de líquido sobre a superfície do cilindro, em padrão espiral. Para ajudar a distribuir o líquido lateralmente e assim melhorar a uniformidade da espessura, cada tira de líquido aplicada pela agulha passa por meio de uma lâmina flexível. Este processo leva a um revestimento que apresenta um padrão espiral na espessura da camada revestida que pode causar defeitos no processo eletrofotográfico.O conhecimento, de forma fundamental, do escoamento é vital para a otimização do processo. Um modelo teórico de escoamento de filmes finos sobre superfícies cilíndricas em rotação com uma porta de injeção de líquido em movimento é apresentado. Este modelo é baseado na teoria de lubrificação considerando um filme precursor na frente da linha de contato aparente. A espessura de filme revestido foi obtida através da solução de uma equação diferencial parcial não linear de quarta ordem usando o método de diferenças finitas de segunda ordem. A discretização do tempo foi feita pelo método implícito de Crank- Nicholson. A discretização do sistema a cada passo do tempo leva a um sistema de equações algébricas não lineares que foi resolvido pelo método de Newton. Os resultados mostram como a uniformidade da camada depositada varia com os parâmetros do processo e com as propriedades do líquido.
Photosensitive cylinders are used in printing arts and more particularly in electrophotographic printing (e.g. xerographic copy). The photosensitive coating is applied to the cylinder in liquid form, before it is solidified. The liquid is applied to the cylinder through a needle applicator that translates along the direction of the cylinder axis. The cylinder rotates during this process in order to cover the entire surface. Therefore, the liquid is applied in a spiral pattern. In order to help spreading of the liquid over the cylinder surface and to improve the thickness uniformity, each liquid stream applied from the needle passes under a flexible blade. This process leads to a coating that presents a spiral pattern on the deposited layer thickness, which can cause defects on the electrophotographic process. The complete understanding of the flow is vital to the optimization of the process. A theoretical model of the thin film flow over the surface of a rotating cylinder is presented here. It is based on the lubrication approximation considering a thin precursor film in front of the apparent contact line. The resulting non-linear fourth-order PDE for the film thickness was solved by a second-order finite difference method. The time discretization was done by the implicit Crank-Nicholson scheme. The non-linear algebraic equation at each time step was solved by Newton’s method. The results show how the uniformity of the deposited layer varies with process parameters and liquid properties.
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SILVA, LUIS DIEGO VALDEZ. "SLOT COATING OF PARTICLE SUSPENSION". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2013. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=23831@1.
Testo completoAbstract (sommario):
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
FUNDAÇÃO DE APOIO À PESQUISA DO ESTADO DO RIO DE JANEIRO
PROGRAMA DE EXCELENCIA ACADEMICA
O processo de revestimento por extrusão é muito usado na fabricação de produtos de alta tecnologia tais como circuitos flexíveis, telas LCD e OLED, dentre outros. A espessura do filme revestido depende da vazão de alimentação e da velocidade do substrato. O estudo do escoamento na região de aplicação é de muita importância, devido à influência que tem sobre a qualidade do filme revestido. A grande maioria dos trabalhos disponíveis na literatura consideram o líquido como um fluido Newtoniano. Porém, nos processos de revestimentos nas indústrias, os líquidos comumente usados são soluções poliméricas e suspensões de partículas. O efeito da presença de moléculas poliméricas dissolvidas no fluido de trabalho nos padrões de escoamento e consequentemente na janela de operação do processo foi estudado recentemente, contudo, o efeito de partículas suspensas no escoamento é ainda desconhecido. O objetivo deste trabalho é compreender melhor a influência da suspensão de partículas no padrão de escoamento que ocorre na região de aplicação de um filme fino de líquido sobre um substrato em movimento. A variação local da concentração de partículas no líquido pode levar a grande variações na viscosidade e consequentemente mudanças no escoamento e nos limites do processo. Neste estudo, considera-se a suspensão como um sistema formado por um fluido Newtoniano como a fase contínua e partículas esféricas rígidas como a fase dispersa. A equação de transporte de partículas engloba os efeitos de difusão de partículas devido a gradientes de concentração, viscosidade e taxa de deformação. As equações de transporte de partículas em conjunto com as equações de conservação de massa e quantidade de movimento são usadas para descrever o escoamento bidimensional com fronteiras livres. Estas equações são resolvidas aproximadamente pelo método de Galerkin/Elementos Finitos. A validação do código numérico foi feita comparando com resultados analíticos disponíveis para escoamento em tubos de seção circular. Os resultados obtidos para o escoamento no precesso de revestimento por extrusão mostram as regiões de maior e menor concentração de partículas e como esta variação altera o escoamento, e a variação da concentração ao longo da espessura do filme depositado.
Slot coating process is commonly used in the manufacture of high technology products such as flexible circuits, LCD and OLED displays, among others. The thickness of the coated liquid film depends on the flow rate and substrate velocity. It is very important to study the flow in the coating bead region, because the flow pattern has a strong effect on the quality of the coated film. Most of the available studies on slot coating consider the fluid as a Newtonian liquid. However, coating liquids are usually polymer solutions or particle suspensions. The effect of dissolved polymer molecules in the flow has been analyzed recently. However, the effect of suspended particle remains unknown. The goal of this work is to develop a fundamental understanding of the effect of suspended particles in the flow pattern in a slot coating process. The local changes in particle concentration can lead to great changes in the local liquid viscosity and consequently in the flow and process limits. In this research, the particle suspension is a system composed by a Newtonian liquid as a continuous phase and rigid spherical particles as the dispersed phase. The particle transport equations takes into account the diffusion due to gradients of concentration, viscosity and deformation rates. The particle transport equation together with the mass and momentum conservation equations are used to describe the two-dimensional free surface flow. These equations are solved using the Galerkin/Finite element method. The numerical code was validated by comparing numerical prediction obtained in circular tube flow with the available exact solution. The results obtained in slot coating flow show regions of high and low concentration of particles and its effect of the flow, and the variation of particle concentration in the deposited thin film.
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ARAUJO, SIMONE BOCHNER DE. "SLOT COATING OF PARTICLE SUSPENSION". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2014. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=24640@1.
Testo completoAbstract (sommario):
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOO processo de revestimento por extrusão é um método muito utilizado na manufatura de diversos produtos. Ele pertence à uma classe de processos de revestimento chamada revestimento com vazão pré-fixada: para operações em regime permanente, a espessura da camada de líquido revestida é definida pela vazão na entrada do equipamento e pela velocidade do substrato. Para diversas aplicações, o líquido de revestimento é uma suspensão de partículas. A abordagem comumente usada é analisar o escoamento como se o fluido fosse Newtoniano, onde sua viscosidade é avaliada pela concentração média de partículas. Porém, dados experimentais mostram que a distribuição de partículas não é uniforme em escoamentos com cisalhamento. Além disso, a distribuição de partículas no filme após o processo de revestimento afetará a estrutura final do filme e, consequentemente, a qualidade final do produto. Portanto, é importante entender os fundamentos do processo de revestimento com suspensão de partículas para melhor descrever este processo e prever comportamentos desse escoamento. O objetivo do presente trabalho é estudar diferentes mecanismos de migração de partículas em suspensão que podem afetar a distribuição de partículas no filme revestido; como mecanismos de difusão e sedimentação. O modelo apresentado leva em consideração a dependência da viscosidade pela concentração local de partículas e o efeito de Marangoni. Dois modelos diferentes foram usados para estudar o escoamento de Marangoni. No primeiro, o transporte de partículas entre a superfície e o escoamento é considerado muito mais rápido que a difusão no escoamento de tal forma que o fluxo líquido é zero e a concentração de partículas na região do escoamento próxima à superfície. No segundo, um modelo mais completo, os efeitos de adsorção e dessorção de partículas pela interface é considerado. O sistema final de equações e não-linear e, com as condições de contorno apropriadas, é resolvido pelo método de Galerkin em elementos finitos e pelo método de Newton. O escoamento é bi-dimensional e, portanto, elementos bi-dimensionais são utilizados para descrever o domínio do problema. Entretanto, para avaliar a concentração ao longo da superfície, foi necessário criar um elemento uni-dimensional. O acoplamento entre estas duas classes de elementos também é discutido. Os resultados mostram que a distribuição de partículas do filme revestido é uma forte função da espessura do filme e das propriedades da suspensão, como a densidade das partículas e coeficientes de difusão. O escoamento de Marangoni pode afetar o padrão de recirculação e a distribuição de concentração de partículas. Além disso, os resultados mostram que a adsorção e dessorção de partículas na interface afetam fortemente a distribuição de partículas.
Slot coating is a common method in the manufacturing of a wide variety of products. It belongs to a class of coating method known as premetered coating: in a steady state operation, the thickness of the coated liquid layer is set by the flow rate fed to the die and the speed of the substrate moving past, and is independent of other variables of the process. For many applications, the coating liquid is a particle suspension. The commom simplified approach is to study the flow as Newtonian and evaluate its viscosity based on the average particle concentration. However, experimental data shows that particle distribution is in fact non-uniform in shear flows. Moreover, particle distribution along the film thickness during the coating process will affect the final fim structure and consequently product performance. Hence, it is important to understand the fundamentals of coating process with particle suspension to better describe and predict the behavior of the flow and the particle distribution in the coated layer. The goal of the present work is to study different particle migration mechanisms in a suspension that may affect particle distribution in the coated film; such as diffusive mechanisms and sedimentation. The model presented takes into account the viscosity dependency and local particle concentration and surface-active particles, i.e. Marangoni effect. Two different approaches were used to study Marangoni flow. First, the bulk-interface transport is considered much faster than bulk diffusion such that the net flux is zero and surface concentration is equal bulk concentration. The second, more complete model, considers adsorption and desorption fluxes from the interface. The non-linear system of equations, with appropriate boundary conditions, is solved by Galerkin Finite Element Method and Newton s Method. The flow is two-dimensional and therefore two-dimensional elements are used to describe flow domain. Nonetheless, in order to evaluate particle concentration along the interface a one-dimensional element was created. The coupling between those two classes of elements of discussed. The results show that the particle distribution on the coated layer is a strong function of the film thickness and suspension properties, such as particle density and diffusion coefficients. The Marangoni flow associated with surface tension gradient due to particle concentration variation along the interface can change the recirculation pattern and particle concentration distribution. Furthermore, the results show that particle adsorption and desorption from interface have a strong effect on the particle distribution.
38
Zhou, Qixin. "Flow Accelerated Organic Coating Degradation". Diss., North Dakota State University, 2014. https://hdl.handle.net/10365/27242.
Testo completoAbstract (sommario):
Applying organic coatings is a common and the most cost effective way to protect metallic objects and structures from corrosion. Water entry into coating-metal interface is usually the main cause for the deterioration of organic coatings, which leads to coating delamination and underfilm corrosion. Recently, flowing fluids over sample surface have received attention due to their capability to accelerate material degradation. A plethora of works has focused on the flow induced metal corrosion, while few studies have investigated the flow accelerated organic coating degradation. Flowing fluids above coating surface affect corrosion by enhancing the water transport and abrading the surface due to fluid shear. Hence, it is of great importance to understand the influence of flowing fluids on the degradation of corrosion protective organic coatings. In this study, a pigmented marine coating and several clear coatings were exposed to the laminar flow and stationary immersion. The laminar flow was pressure driven and confined in a flow channel. A 3.5 wt% sodium chloride solution and pure water was employed as the working fluid with a variety of flow rates. The corrosion protective properties of organic coatings were monitored inline by Electrochemical Impedance Spectroscopy (EIS) measurement. Equivalent circuit models were employed to interpret the EIS spectra. The time evolution of coating resistance and capacitance obtained from the model was studied to demonstrate the coating degradation. Thickness, gloss, and other topography characterizations were conducted to facilitate the assessment of the corrosion. The working fluids were characterized by Fourier Transform Infrared Spectrometer (FTIR) and conductivity measurement. The influence of flow rate, fluid shear, fluid composition, and other effects in the coating degradation were investigated. We conclude that flowing fluid on the coating surface accelerates the transport of water, oxygen, and ions into the coating, as well as promotes the migration of coating materials from the coating into the working fluid, where coatings experience more severe deterioration in their barrier property under flowing conditions. Pure water has shown to be a much more aggressive working fluid than electrolyte solutions. The flowing fluid over the coating surface could be used as an effective acceleration method.NDSU Advance FORWARD Program; NSF HRD-0811239
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Hewson, Robert William. "Tri-Helical direct Gravure coating". Thesis, University of Leeds, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525486.
Testo completoAbstract (sommario):
Tri-helical, gravure roll coating, operated in reverse mode, is investigated via a combined experimental, theoretical and computational approach. New experiments were conducted on a pilot coating rig, designed to simulate the industrial process. Flow visualisations reveal the underlying flow structure within the roll-to-web transfer region and highlight when loss of coating stability (streaking) occurs. The latter is found to be influenced by the depth of the tri-helical grooves and the capillary number. Experiments show that as the web-to-roll speed ratio is increased, so too is fluid pickout from the grooves, although the coated film thickness may decrease. A key feature of the present investigation is the formulation of a novel complementary mathematical model. By starting with a simplified form of the coating process and progressively adding complexity a set of models are developed, first for simple zero pitch angled rectangular grooves then for grooves of arbitrary shape and groove pitch. A further extension to the model is the inclusion of a non-Newtonian model for the fluid (specifically a shear thinning power law formulation). Analysis of the application of shear thinning fluids to the moving substrate is also conducted. The base model developed is that for rectangular grooves of zero pitch, which takes the form of an analytical solution of the flow equation (a Poisson equation) along a groove. An extension to this model is made by solving the Poisson equation for non-rectangular grooves using the finite element method. Simple meniscus models were applied to make the problem tractable. Agreement between experimental data and predictions from the model is seen to be good for the range of operating conditions considered up to the onset of streaking. A final extension to the model considers grooves at non-zero pitch angles, representative of the industrial coating process. The limitations of this model, when compared to experimental data are examined and a physical explanation is postulated for the breakdown of the model at steep pitch angles. Under conditions of breakdown, the high pressures within the groove are consistent with the idea that elastohydrodynamics is an important mechanism in the transfer of fluid within the coating bead for discrete cell gravure coating.
40
Eckermann, Jurgen. "Optimising high speed coating processes". Thesis, Swansea University, 2012. https://cronfa.swan.ac.uk/Record/cronfa42471.
Testo completoAbstract (sommario):
The coil coating process of strip steel is a continuous and highly automated process in which the aim is to apply a paint layer of uniform thickness onto metal sheet at high operational speed. However, the performance of the coil coating process has been limited due to the occurrence of coating defects, such as ribbing and fat edges, which leads ultimately to a reduction in the operational speed of coating. Therefore, in order to enhance coating productivity, the complex flow behaviour of commercial paints needs to be fully understood. Consequently, the main objective of this work was to obtain rheological parameters for the commercial paints using rotational Rheometers, Capillary Break-up Rheometer and Capillary Extrusion Rheometer to allow the characterisation of the complex flow behaviour. This research project was tailored over its course to generate a solid knowledge foundation of the rheological properties of polyester resin based paints prior to the defining of different experimental procedures so as to guarantee the reproducibility of the data measured with various Rheometers. Once these rheological characteristics were fully understood for one paint, the project was moved forward by selecting other commercially available paints which were similarly analysed to allow a comparison of the various rheological behaviours. One key finding was that the commercial paints behaved in either a Newtonian or a Non Newtonian fashion. The Non Newtonian paints possessed a high internal microstructure which was reflected in the degree of elasticity exhibited, whereas the Newtonian paint did not seem to exhibit any elasticity. Furthermore, a mutual, ideal operability window for the Capillary Break up Rheometer could be derived from data which was systematically collected by varying the input parameters including opening time, stretch profile and Hencky strain. Capillary Extrusion Rheometer provided extensional and shear information at very high strain rates. At the end, a steady state flow curve for both shear and extensional viscosity could be determined for a strain rate range of 10-1 to 5 x 104, which is unique for the polyester resin based paints analysed in this work.
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Graham, David W. "Corrosion resistant chemical vapor deposited coatings for SiC and Si₃N₄ /". This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-09292009-020327/.
Testo completo
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Bhallamudi, Vidya Praveen. "Coating high temperature lead wires with electrically insulating alumina by electrophoretic deposition and slurry coating". The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1311955861.
Testo completo
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Singh, Rajnish Kumar Materials Science & Engineering Faculty of Science UNSW. "Contact deformation of carbon coatings: mechanisms and coating design". 2008. http://handle.unsw.edu.au/1959.4/43102.
Testo completoAbstract (sommario):
This thesis presents the results of a study focussed on the elucidation of the mechanisms responsible for determining the structural integrity of carbon coatings on ductile substrates. Through elucidation of these mechanisms, two different coating systems are designed; a multilayered coating and a functionally graded coating. While concentrating upon carbon coatings, the findings of this study are applicable to a broad range of hard coatings on ductile substrates. The thesis concludes with a chapter outlining a brief study of the effects of gold coatings on silicon under contact load at moderate temperatures to complement the major part of the thesis. Carbon coatings with differing mechanical properties were deposited using plasma enhanced chemical vapour deposition (PECVD), filtered assisted deposition (FAD) and magnetron sputtering deposition methods. Combinations of these techniques plus variation of deposition parameters enabled composite multilayered and functionally-graded coatings to also be deposited. Substrates were ductile metals; stainless steel and aluminium. Characterisation of the coating mechanical properties was undertaken using nanoindentation and nano-scratch tests. The same techniques were used to induce fracture within the coatings to allow subsequent analysis of the fracture mechanism. These were ascertained with the assistance of cross-sectional imaging of indents prepared using a focussed ion beam (FIB) mill and transmission electron microscopy (TEM) using specimen preparation techniques also utilising the focussed ion beam mill. A two dimensional axisymmetric finite element model (FEM) was built of the coating systems using the commercial software package, ANSYS. Substrate elastic-plastic properties were ascertained by calibrating load-displacement curves on substrate materials with the finite element model results. Utilising the simulation of spherical indentation, the distribution of stresses and the locations for fracture initiation were ascertained using finite element models. This enabled determination of the influence such factors as substrate mechanical properties, residual stresses in the coatings and importantly the variation of elastic properties of the different coating materials. Based upon the studies of monolithic coatings, simulations were undertaken on multilayer and functionally-graded coatings to optimise design of these coating types. Based on the results of the modelling, multilayered and functionally graded coatings were then deposited and mechanical testing undertaken to confirm the models. Three major crack types were observed to occur as the result of the spherical nanoindentation on the coatings; ring, radial and lateral cracks. Ring cracks were found to initiate from the top surface of the film, usually at some distance from the edge of the spherical contact. Radial cracks usually initiated from the interface between the coating and the substrate directly under the symmetry axis of indentation and propagated outwards in a non symmetrical star-like fashion. Lateral cracks formed either between layers in the multilayer coatings or at the interface with substrate. Ring and radial cracks were found to form upon loading whereas lateral cracks formed upon both loading and unloading depending upon the crack driving mechanism. Pop-in events in the load displacement indentation curve were found to be indicative of the formation of ring cracks, while the formation of the other types of cracks was not signified by pop-ins but rather by variations in the slope of the curve. The substrate yield strength was found to influence the initiation of all crack systems while compressive stresses in the coating were seen to only influence the formation of ring and radial cracks. However, it was also noted that the initiation of one form of crack tended to then hinder the subsequent formation of others. In multilayer coatings, the lateral cracks were suppressed, as opposed to the monolayer coating system, but a ring crack was observed. This drawback in the multilayer system was successfully addressed by the design of a graded coating having the highest Young??s modulus at the middle of the film thickness. In this coating, due to the graded nature of the elastic modulus, the stresses at the deleterious locations (top surface and interface) were guided toward the middle of coating and hence increased the load bearing capabilities. The effect of substrate roughness upon the subsequent surface roughness of the coating and also upon the fracture process of the coating during indentation was also investigated. For the coatings deposited on rough substrates, the radial cracks were observed to form initially and this eventfully delayed the initiation of ring cracks. Also the number of radial cracks observed at the interface was found to be proportional to the distribution of the interfacial asperities. In summary, the study elucidated the fracture mechanisms of monolayer, multilayer and graded carbon coatings on ductile substrates under uniaxial and sliding contact loading. The effects of the yield strength, surface roughness of the substrate, along with the residual stress and elastic modulus of the coatings on the fracture of coatings were investigated. The study utilised finite element modelling to explain the experiments observations and to design coating systems.
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Prall, Katharina Maria. "The viscoelastic behavior of pigmented latex coating films /". 2000. http://www.library.umaine.edu/theses/theses.asp?Cmd=abstract&ID=CHE2000-001.
Testo completo
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Shieh, Cheng-Liang, e 謝政良. "A Study on Coating for Evaporative Pattern Coating". Thesis, 1995. http://ndltd.ncl.edu.tw/handle/04677289894202045532.
Testo completo
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Chin, Chih-Ping, e 秦志平. "Coating Window Study in Industrial Angled Slot Coating". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/03017364194491807070.
Testo completoAbstract (sommario):
碩士元智大學
化學工程與材料科學學系
95
Slot die coating is a common method in the manufacture of a wide variety of products. It belongs to a class of coating method known as pre-metered coating: the thickness of the coated liquid layer in principle is set by the flow rate fed to the die and the speed of the substrate moving past, and is independent of other process variables. Thus, pre-metered methods are ideal for high precision coating. The important operating limits of slot coating are the minimum thickness that can be coated at a given substrate speed, generally referred to as the low-flow limit and coating window which is used to reflect the flexibility in suitable operation condition range. The coating flow examined as labeled angled slot die coating, was that where a substrate contacts a sheet of liquid forming an angled flows with the vertical to the substrate, so that it intersects the liquid along a wetting line which was not perpendicular to the direction of its motion. Although most of the liquids coated industrially are polymeric solutions and dispersions that are not Newtonian, previous analyses of the low-flow limit and coating window in slot coating dealt only with Newtonian liquids. The experiments were carried out with various kinds of liquids hard coating and polysilica solution which are Newtonian fluid and power law fluid and both are used in real industrial coating process to determine the coating effect on the substrate velocity when coating defects appeared. It was observed that coating defects are delayed to higher speeds and expanded to larger flow rate, as this angle of the die departs from vertical. The experiment data show that the speed which is relevant to coating defects is not the velocity of the substrate itself but its component normal to the wetting line. Variation of the die geometry also can influence the coating window and its coatability, and even shift the low-flow-limit in higher speed and give thinner film thickness. The experiment data show that Bead vacuum effect and blade effect are formed by changing the die geometry without using any assistant equipment, which can make the coating bead stable and uniform the film thickness. These results have important practical implications and suggest that these fundamental principles are also applicable to other coating flows.
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Rukosuyev, Maxym. "Atomization based dual regime spray coating system: design and applications". Thesis, 2017. https://dspace.library.uvic.ca//handle/1828/8481.
Testo completoAbstract (sommario):
In modern research and industrial applications, the importance of coatings can hardly be underestimated. Coatings are used extensively in optics, biomedical instruments, cutting tools, and solar panels to name a few. The primary purpose of any coating is to alter surface properties of the base material thus adding new functionality or improving the performance of the original product. A multitude of coating techniques has evolved over the years with spray coating being one of the more widely used. Some applications require deposition of materials that are either in the form of a solution or suspension. Therefore, before or during the deposition process small droplets of the said liquid are formed and transferred onto the substrate. Since differently sized droplets have different surface impact dynamics, droplet velocity at the impact plays an important role in the way it will adhere to the surface. Most spray coating techniques do not take into account the process of droplet-surface interaction which may result in overspray, poor coating thickness control, and material waste.
The research presented in this dissertation outlines the supporting principles, design, fabrication and testing of an innovative spray coating system that provides the ability to fine tune coating parameters, including droplet impact velocities, to provide close to optimum deposition conditions. The core of the design consist of a dual velocity nozzle unit that ensures acceptable range of droplet velocities at the surface, while keeping droplets from accelerating excessively inside the system. Early experiments showed the system’s potential to produce nanoparticle coatings with particles uniformly distributed across the substrate. In addition, pigment coating for improved 3D scanning was also performed, thereby improving the surface definition and accuracy of the scanning results. Scalability of the system also led to experiments in applying this technology to microprinting. Preliminary microprinting results illustrated the system’s flexibility and opened new research avenues in micro-coating, microprinting, and, possibly rapid prototyping. Furthermore, thanks to the highly adaptable nature of the proposed design, seamless incorporation of a torch-like device into the nozzle unit was also possible. That provided the opportunity to perform in situ thermal processing or sintering of deposited material as well as production of a nanoparticle coating in a one-step process by thermally decomposing precursor solution.
Technology developed during the research work presented in this dissertation demonstrated its ability to be adapted in a number of applications that can benefit both industry and engineering research alike. Large area coatings, nanoparticle production, micro-coating, and coatings for improved 3D scanning are just a few areas where the presented technique can already, or may, if developed further, outperform existing and widely accepted methods. Fine tuning of the system to a particular application, and tapping into its potential in other fields will be explored in future research.Graduate
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Lee, Chia Ching, e 李嘉慶. "The Study of Thin Film Coating : Gravure Coating and Tensioned Web Slot Coating with Vacuum". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/02146264446884625231.
Testo completo
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"Two Coating Problems: Thin Film Rupture and Spin Coating". Diss., 2009. http://hdl.handle.net/10161/1087.
Testo completo
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Froehlich, Mihaela. "Two Coating Problems: Thin Film Rupture and Spin Coating". Diss., 2009. http://hdl.handle.net/10161/1087.
Testo completoAbstract (sommario):
In this work we study two fluid dynamics problems which are of particular interest in industries where thin film coating is a part of a production process, like optical coating, insulating layers in micro-circuitry, adhesives and painting. Experiments show that for very thin films of viscous liquids van der Waals intermolecular forces can produce instabilities leading to film ruptures. We consider this problem of thin film rupture driven by van der Waals forces and look for axisymmetric steady state solutions. Small perturbations from these solutions will lead to finite-time rupture. Using different numerical approaches we look for the solutions close to rupture. We obtain more solutions via shooting method and show that finite difference schemes on uniform grids are inferior to shooting for this problem. The second problem comes from a process called spin coating, one of the methods used to coat uniform thin films in variety of industrial applications such as manufacturing magnetic and optical discs. In spin coating a drop of liquid spreads radially due to centrifugal effects from spinning and eventually yields a thin film of uniform thickness formed on the solid surface. In experiments fingering instabilities at the expanding front of the fluid layer have been observed. This has renewed interest in the study of the nonlinear dynamics of such problems. We derive the evolution equation for thin films in rotating polar coordinates. We solve the axisymmetric problem and give numerical and analytical results for steady states. For large fluid volumes in rotating cylinders, we show that when centrifugal and gravity forces dominate, steady state solution free-surface profiles are parabolas for the angular velocity less then the critical velocity, and for higher velocities film ruptures, producing truncated parabolic profiles with circular contact lines. We find the similar results for the steady state case when centrifugal and surface tension forces are dominant. FInally, we study the dynamics of the spin coating again considering three cases, as weill as including the influence of van der Waals and Marangoni forces.
Dissertation