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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.
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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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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.
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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 i in. "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.
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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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Sjödin, Isak. "Cool Roof Coatings on Industrial Buildings : An Energy Study of Reflective Coatings". Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-157503.
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To evaluate the effect of cool roof coatings containing Expancel® thermoplastic microspheres on industrial buildings, a warehouse was built-up in the computer simulation software IDA-ICE. The warehouse was modelled in line with ASHRAE 90.1. 2004 ”Energy Standard for Buildings Except Low-Rise Residential Buildings”. Four different cases were set up where the coating of the roof was the only variable. Two coatings containing Expancel® microspheres - one white and one red coating were compared to the same white coating without Expancel® microspheres and the ”base case” where there is no coating at all. The same circumstances were also implemented in a practical laboratory test using a model warehouse with a detachable roof. Four interchangeable roofs with different roof coatings constitute the various cases in the laboratory tests. A ”sun” consisting of statically mounted IR light bulbs were constructed, as well as a cooling system to measure the difference in cooling effect (maintaining a constant indoor temperature) between the different cases as a result of the change in insolation. The results of the computational simulations show that for a warehouse placed in Houston, Texas about 50 MWh in combined heating and cooling energy can be saved yearly between the best and the worst case, a reduction of 6.2%. Changing the geographic placement of the warehouse to Tepic, Mexico the corresponding savings were determined to 83 MWh or 13.5%. A way of determining the yearly savings in heating and cooling amount for the warehouse with a generic roof coating, only knowing the SRI value of the coating, was developed. It was determined that for every unit-increment of the SRI value the yearly savings for the warehouse placed in Houston, Texas were 718 kWh and 0.1%. The corresponding savings for the warehouse placed in Tepic, Mexico were determined to be 1252 kWh and 0.22%. The laboratory tests showed that the indoor temperature of the model warehouse decreased by close to 16°C between the best and the worst case.
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OZZELLO, ELENA DANIELA. "UV-cured fouling release acrylic coatings and protective coatings for clay bricks". Doctoral thesis, Politecnico di Torino, 2018. http://hdl.handle.net/11583/2716632.
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The topic of this thesis is the protection of surface through UV cured polymeric coatings. In the first part coatings are designed to inhibit the adhesion of microorganisms on different substrate, while in the last chapter the coatings are developed to protect clay bricks from water. Degradation of surfaces caused by biofouling is a common issue in a variety of application, such as naval equipment, food industry and biomedical implants. In clay bricks, in addiction to biodegradation, the water causes other aesthetical and functional degradation phenomena, such as delamination, cracking, efflorescence, patina, black crusts.
In this thesis was studied the growth of yeast in presence of different polymeric coatings prepared by UV curing. The approach followed was mainly based on the interfacial interactions between the surfaces and the microorganism. The experimental methods have been designed in order to control the physicochemical and mechanical properties of the surfaces. Interface interactions are governed by a variety of parameters, depending on the characteristic of both the substrate and the microorganism. Surface tension, hydration, wettability, roughness, topographies and elastic modulus and glass transition temperature are influent factors for polymeric materials.
The microrganism selected for this works was a yeast isolated from garden soil and identified as Rhodotorula mucillaginosa. Rhodotorula species are ubiquitous, filmogenic, pigment yeasts. They are often called “pink yeast” because of the peculiar pink to orange coloration of the colonies. R. mucillaginosa and its adhesion properties are interesting in different application field. Selective and controlled proliferation of R. mucillaginosa could be useful in soil and wastewater bioremediation and industrial production of carotenoids. On the contrary, in biomedical application the biofilm formation in not desirable. Despite R. mucillaginosa generally is not harmful for human health, it is known as an emergent opportunistic pathogen able to infect immunosuppressed adults and newborns. Another important risk factor in infected patients is the presence of foreign bodies. Despite this, the Biosafety level of R. mucillaginosa is 1, this means that its manipulation in laboratory does not required special precautions.
Coatings were prepared by UV-induced crosslinking processes. The UV curing or photopolymerization technique consists in the fast transformation of a liquid mixture of precursors into a solid crosslinked polymeric film. Low energy requirements, room temperature operation and solvent-free systems make UV curing an ecofriendly technology suitable for coatings industries.
Monomers selected for the UV-curing process were characterized by acrylic end groups assuring fast and complete polymerization. For the protection of substrate against fouling, different monomers were selected in order to obtain coatings with different surface properties:
1. Hydrophobic monomers, i.e. perfluoropolyether diacrylates
2. Hydrophilic monomers, i.e. polyethilenglycol diacrylates.
Hydrophobic coatings were based on perfuoropolyether (PFPE) diacrylic oligomer. It was studied the effect of surface tension, topography and elastic modulus on R. mucillagionosa adhesion and release. In Hydrophilic coatings were compared the effect of alkyl and poly(ethylene oxide) chain. The attention was focused on the effect of different chemical compositions, and thus different surface tension, on the induced morphology of R. mucillaginosa. Properties of acrylic coating have been checked by water absorption, contact angle measurement, profilometry and dynamic mechanical thermal analysis (DMTA).
The interaction between the coatings and the yeast cells were examined through a simple in vitro test and correlated to the material properties of the polymers. The yeast test was designed to monitor the growth of R. mucillaginosa and the potential biofilm formation in presence of acrylic coatings. Biofilm release by a gentle washing was also evaluated. During the test, cell density was measure by UV visible spectroscopy. The growth morphology of the yeast on the coatings surface was observed by optical microscopy and FESEM. In addition, the effect of uncured monomers and the photoinitiator on the microorganism growth was studied.
The coatings under investigation showed a different fouling behavior. The interaction between yeast cells and the coating surface appreciably change, mainly driven from the surface tension and the hydration of the materials. Different yeast morphologies were found.
In the second part of the thesis are presented two hybrid coating as protective coating for clay bricks: a waterborne polyurethane coating and a perfluorinated (PFPE) coating. Masonry is susceptible from aesthetic and functional deterioration due to atmospheric agents, pollution and microorganism. The most diffuse degradations of facing bricks are lacunas, pulverization, delamination, cracking, presence of efflorescence, patina, black crusts and dissolution and leaching of mortar between brick courses.
Water is known as an important factor of degradation; thus, hydrophobic coatings is an effective way to preserve bricks. The main characteristic required to this coating are hinder the liquid water absorption but maintain the water vapor transmission in the substrate.
Protective coating for building porous materials are divided in two main categories: film formers and penetrants. The first coating presented in this thesis is a polyurethane based film formers coatings. It was prepared by combining two ecofriendly process: UV-curing of a waterborne diacrylic polyurethane and sol-gel reaction of a Tetraethoxysilane (TEOS).
The perfluorinated coating is penetrants and was obtained by a sol-gel reaction of an α–ω-terminated triethoxysilane PFPE. Hybrid PFPE was obtaind using the sol-gel process in the presence of TEOS.
Coated and uncoated facing bricks were compared by scanning electron microscopy, surface profilometry, water wettability and capillary rise tests. The hybrid coating acts as a moderate water repellent: interestingly no appreciable alteration of the aesthetical properties of the brick was observed, in particular no gloss and color change appeared after the treatment.
Both the proposed coating could be applied on brick in the manufacturing process, or on existing brickwork.
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Bettley, Alison. "Electroplated titanium coatings". Thesis, Open University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305065.
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Alyamac, Elif. "Self-Stratifying Coatings". University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1259474985.
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Chen, Long. "Self-Stratifying Coatings". University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1376480287.
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Bunker, Daniel Thomas. "The Influence of drying rate on the pore volume distribution of clay coatings". Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/5783.
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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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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.
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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.
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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/.
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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.
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Pickles, Matthew Jonathan. "Hydrodynamic erosion of coatings". Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243503.
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Moh, Sarfaraz. "Microwave assisted sputtered coatings". Thesis, University of the West of Scotland, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556071.
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Oki, Makanjuola. "Conversion coatings on aluminium". Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390302.
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Walker, Dane E. "Enhanced molybdate conversion coatings". Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/12209.
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The replacement of chromate conversion coatings for zinc coated components has been necessitated by the materials finishing industries due to the inherent toxicity issues with Cr(VI) and the legislative enforcement of WEEE and ELV Directives by the European Union. Current replacements are based on non-chromate , Cr(III) systems, these may be perceived by some to be problematic as they still contain chromium . Molybdate based conversion coatings have long been viewed by many researchers to be a viable non-chromium alternative due to their low toxicity. An extensive literature review of the research carried out in the last 20 years was carried out, highlighting areas of interest for improving the corrosion resistance of the coatings studied. These were, primarily, the synergesis that exists with molybdate and phosphate compounds for corrosion resistance and the incorporation of nanoparticle silica into treatment solution. Also discovered was the importance of the acid used to adjust treatment solution pH, immersion time, oxidising agent additions and the incorporation of rare earth metal species. Silicate sealant layers were also highlighted as a post treatment. Molybdate-based coatings were formed on commercial electrodeposited acid zinc surfaces. Many treatment conditions were investigated, and initially performance analysed using DC Linear Polarisation Resistance (LPR) trials. Subsequently, the highest performing coatings were subjected to the more aggressive, industry standard, ASTM B 117 Neutral Salt Spray (NSS) corrosion test. The highest performing molybdate coatings were found to have an average LPR of ~ 9 000 Ω. cm2, in contrast to ~ 12 000 Ω. cm2 for the Cr(VI) based reference. NSS results were amongst the highest performing for molybdate based coatings documented, at 24 h until 5% white rust, however remained inferior to Cr(VI) coatings, which lasted 120 h. The highest performing coatings were characterised using FEG-SEM, Cryofracture EDXA and site specific AES. These techniques revealed that the enhanced molybdate coatings had a columnar structure that was around 300 nm thick, with pores that appeared to expose the substrate. AES showed this type of coating to have a mixed Mo, P and Zn oxide surface. Corrosion initiation was also studied; this can be thought of as an investigation to determine the point(s) of weakness or the mechanism that causes coating failure. Coatings were immersed in 5 % wt/ vol NaCl(aq) until they showed any surface change. Initial signs of corrosion were deemed to be any appearance of pitting or discolouration of the film, not a voluminous corrosion product. Untreated Zn, Cr(VI) and simple molybdate coatings were studied as well as enhanced molybdate coatings. There were clear differences in the way the coatings behaved at the onset of corrosion. Cr(VI) coatings delaminated, leaving an area of decreased Cr concentration. The enhanced molybdate coatings failed by the appearance of localised pores of ~ 70 µm in diameter. Substrate exposure was indisputably the reason for coating failure in chloride environments. In light of the work carried out in the present thesis the outlook for the use of molybdate as a potential replacement for chromate for the conversion coating of electrodeposited zinc surfaces is a positive one.
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Denisov, V. N., B. N. Mavrin, E. A. Vinogradov, S. N. Polyakov, A. N. Kirichenko, K. V. Gogolinsky, A. S. Useinov i in. "Characterization of TiAlN coatings". Thesis, Видавництво СумДУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20448.
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Chakravorty, Asima. "Stable Fluorinated Antimicrobial Coatings". VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/450.
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Contact antimicrobials for use in the medical device industry are being studied extensively to minimize the risk of hospital acquired infections, which are among the top ten leading causes of death in the US. Surfaces modified with quaternary ammonium containing side chains have been known to demonstrate excellent antimicrobial properties. Prior work has indicated that polyurethane surfaces with copolyoxetane soft blocks consisting of fluorinated and quaternary ammonium side chains can act as good antimicrobials. However, stabilizing the positive charge on the surface has been a challenge. The dissertation is aimed at creating a surface modifier that would confer a stable contact kill antimicrobial surface at very low modifier content, that is, less than 2 wt%. To achieve this objective, the study explored the introduction of a different fluorous group in the soft block to enhance stability. In particular, prior studies by other groups and early work by Kurt have shown that replacement of one of the terminal “chaperone” C-F bonds by C-H decreased surface tension. This led to the hypothesis that a –CF2H terminated “chaperone” group would be “amphiphilic” resulting in surface stability under both dry and wet conditions. Keeping this hypothesis in mind, a –CF2-CF2H (4F) terminal “chaperone” group was created in a modifier having two different 4F to quaternerary C12 ratios. It was found that polyurethanes prepared with a 66:34 ratio of 4F:C12 as the diol, performed as a very good surface modifier with high zeta potentials over a long period of time compared to the –CF3 based modifier. Antimicrobial tests performed within one week and four weeks after coating preparation have provided promising results that demonstrate improved biocidal stability. Guided by improved antimicrobial properties obtained with surface modifier polyurethanes made from P[(4F)(C12)-66:34-Mn], a new concept was explored by end-capping the same diol with isocyanatopropyltriethoxysilane and blending the end-capped diol with base polyurethane along with a 10 wt % cross linker. These modifiers show excellent antimicrobial properties (100% kill of bacteria) over one month with no observable changes in the zeta potential or surface morphologies. XPS analysis confirms the presence of quaternary ammonium on the surface. Preliminary kinetic studies show excellent antimicrobial properties for a 2 wt% modifier and 100% kill within 1 hr.
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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/.
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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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Jain, Rahul. "Investigations on Multiscale Fractal-textured Superhydrophobic and Solar Selective Coatings". Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78725.
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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
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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.
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Chen, Qingyuan. "An experimental study of air entrainment in a blade coating system with a pressurised pond applicator". Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/5807.
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Deogon, Malkit Singh. "A study of intumescent coatings". Thesis, Brunel University, 1989. http://bura.brunel.ac.uk/handle/2438/6297.
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Intumescent coatings are used in the field of fire protection to prevent certain construction elements reaching the critical temperatures at which excessive damage would. occur, thus avoiding premature structural collapse. The studies presented in this thesis have been directed towards an understanding of intumeseent coatings and the process of intumescence. The kinetics and mechanism of intumeseence are discussed. The behaviour of the raw materials used in the preparation of intumeseent coatings, was studied at elevated temperatures using thermal analytical techniques, and new formulations were developed. These formulations were examined In the laboratory using various screening tests and were also subjected to a large scale hydrocarbon fire test alongside other commercially-avallable coatings. A simplified coating formulation with the minimum of ingredients required to produce good intumescent properties was developed. This formulation was subjected to various heat-radiation intensities using an ISO ignitablilty apparatus. The behaviour of the intumescence, process observed was explained by a simple theoretical model. The model of Buckmasterv Anderson and Nachman was used and several new results were derived. In particular a relationship was derived giving the time taken for the temperature at the inner surface of the coating to reach a given value. The durability of the newly-developed intumescent coatings, and methods of improving it, were also investigated.
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König, Meike. "Functional Coatings with Polymer Brushes". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-126365.
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The scope of this work is to fathom different possibilities to create functional coatings with polymer brushes. The immobilization of nanoparticles and enzymes is investigated, as well as the affection of their properties by the stimuli-responsiveness of the brushes. Another aspect is the coating of 3D-nanostructures by polymer brushes and the investigation of the resulting functional properties of the hybrid material. The polymer brush coatings are characterized by a variety of microscopic and spectroscopic techniques, with a special emphasis on the establishment of the combinatorial quartz crystal microbalance/spectroscopic ellipsometry technique as a tool to characterize the functional properties of the polymer brush systems insitu. The pH-responsive swelling of the polyelectrolyte brushes poly(acrylic acid) and poly(2-vinylpyridine), as well as the thermoresponsive swelling of poly(N-isopropylacryl amide) is studied in detail by this technique.
Poly(2-vinylpyridine) and binary poly(N-isopropylacryl amide)-poly (2-vinylpyridine) brushes are used as templates for the insitu-synthesis of palladium and platinum nanoparticles with catalytic activity. As an example for the use of polymer brushes to immobilize enzymes, the model enzyme glucose oxidase is physically adsorbed to poly (2-vinylpyridine) and poly (acrylic acid) brushes and also covalently bound to poly (acrylic acid) brushes. In the last part of this thesis, sculptured thin films are coated with poly (acrylic acid) and poly (N-isopropylacryl amide) brushes and the swelling characteristics as well as the adsorption behavior of the model protein bovine serum albumin are investigated.
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Ramm, David Alfred John. "Mechanics of sprayed composite coatings". Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294397.
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Etheridge, Andrea Mary. "Conversion coatings on aluminium alloys". Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307051.
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Gardner, M. K. "Adhesion of coatings to steel". Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376908.
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Holness, R. J. "Conducting network anti-corrosion coatings". Thesis, Swansea University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637293.
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This Thesis describes the development and electrochemical testing of novel Zinc-Rich Paints (ZRPs) and coatings loaded with conducting polymers (specifically polyaniline) for use in the corrosion protection of steel, zinc and aluminium. Initial work concentrated on the development of model ZRPs using spherical and flake zinc powders dispersed in polyvinyl butyral (PVB). Both morphologies displayed a dramatic increase in through-film electrical conductance when the zinc volume fraction (Φ) reached the critical level (0.28) for long-range charge percolation. At the same level, these coatings sacrificially protect coated steel samples incorporating a defect. The duration of the protection increased with increased Zn volume fraction. The next phase of development saw carbon and a conducting polymer, Polyaniline Emeraldine-Salt (PAni-ES) used as "extenders" within a model ZRP organic coating. It was found that these systems fail to provide protection, despite "extending" charge percolation. This reflects the high level of cathodic activity on carbon itself and a chemical interaction between zinc and PAni-ES which rendered the coatings poor galvanic protectors. Only in instances with a high external cathode area (cut-edges) did the carbon "extended" coatings show acceptable performance. PAni-ES can protect iron and zinc surfaces in its own right. PAni-ES dispersions present in a PVB coating and solution-cast onto iron or zinc were shown to reduce rates of corrosion-driven cathodic disbondment. The presence of an adequate PAni-ES concentration also reduces the level of filiform corrosion on coated aluminium (AA2024-T3) substrates. The PAni-ES works on metal substrates by a combination of (a) raising the surface potential, (b) forming an oxide layer and (c) buffering under-film pH. The ZRPs have been developed into a system close to commercial applicability for the production of domestic appliances and from the data obtained to-date PAni-ES seems appropriate for the protection of a range of metals, as a replacement for the toxic and carcinogenic chromate systems currently in use.
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Geng, Kebin. "MECHANICAL EVALUATION OF NANOCOMPOSITE COATINGS". UKnowledge, 2006. http://uknowledge.uky.edu/gradschool_diss/395.
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An anti-reflective (AR) lens is an ultrathin multilayered structure composing of AR coatings on a lens substrate. These coatings can be made by a spin-coating process with a nanocomposite of UV curable acrylic monomers and well dispersed metal oxide nanoparticles. The in-situ UV polymerization rate was reduced by oxygen inhibition and the absorption of UV energy by the metal oxide nanoparticles. There are few studies of the mechanical properties of ultrathin polymeric coatings that include the effects of substrates, the viscoelastic behaviors of polymers in submicron scales and the effects of multilayered coatings. With a coating system based on UV cured dipentaerythritol pentaacrylate on silicon wafer substrates, nanoindentation tests showed that the nominal reduced contact modulus increased with the indentation load and penetration depth due to the effect of the substrate, in quantitative agreement with an elastic contact model. Ultrathin polymeric coatings subjected to constant indentation loads exhibit shear-thinning during flow. None of the models examined completely described the elastic response of an ultrathin polymeric coating on a compliant plastic substrate. The effective modulus was a function of coating-substrate property, indenter tip size, coating thickness, adhesion and residual stress. It was logarithmic dependent on the ratio of the indentation depth to the coating thickness prior to coating fracture. An elastic model, assuming shear-lag and a plane-stress state, was used to estimate the interfacial strength between a submicron coating and a compliant substrate. The critical indentation load for the indentation-induced delamination of the coating from the substrate increased with the third power of the indentation depth and was a linear function of the reciprocal of the coating thickness. The interfacial strength was 70.4 MPa. Mechanical properties and fracture characteristics of CVD ceramic and nanocomposite coatings on polymer substrates were evaluated by nanoindentation and nanoscratching tests. The AR lenses made with polymer nanocomposite coatings have better mechanical properties due to the close match of properties between the coatings and the plastic substrate. The new approach to making AR lenses with polymer nanocomposites on plastic substrate is promising.
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Brinley, Erik. "TUNABLE NANOSTRUCTURE ANTI-REFLECTIVE COATINGS". Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3923.
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Research was conducted on broadband, anti-reflective coatings for fused silica and chalcogenide substrates in the infrared region of light. Using chemical preparation to create nano-porous through nano-particle based sol-gel solutions, the alteration of optical properties including refractive index and optical thickness was conducted. The nano-particles can modify the coating surface to allow only zero-order diffracted wave propagation reducing scattering while a partially graded profile of refractive index due surface evaporation lessened the precise phase relations of typical homogeneous coatings. My study of silica and titania sol-gel, and hybrid mixtures of the two were used to obtain the optical properties of the materials. The choice of experiments were rooted in theoretically calculated values, and parameters were selected based on quarter wavelength thickness and square root of refractive index theories of destructive cancellation of rebound waves for reduction of reflection. The fused silica system required anti-reflection in the region of 1.0-1.6 micrometer wavelength of the near-infrared. The base, uncoated transmission in this region is ~91%. A maximum transmission of 98% and no less than 97.3% over the entire region of interest was achieved. The chalcogenide system required anti-reflection in the regions of 1.0-1.6 and 3.5-5.0 micrometers of the near- and mid-infrared. The base, uncoated transmission of these regions is 61.9%. A maximum of 95% transmission was achieved for the 1.0-1.6 region and 87% for the 3.5-5.0 region. Solutions and coatings were characterized by Scanning Electron Microscope, Atomic Force Microscopy, X-ray Photoelectron Spectroscopy, particle size, elipsometry, UV-Vis-NIR, and FTIR to reveal the science behind the development and synthesis of nano optical coatings.M.S.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science & Engr MSMSE
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Sturgeon, Andrew John. "Glass-ceramic coatings for metals". Thesis, University of Warwick, 1987. http://wrap.warwick.ac.uk/34630/.
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An investigation was conducted into the coating of metal substrates with a glass-ceramic enamel. Two metal types were coated, a 17% chrome-iron and a low carbon mild steel. The glass-ceramic was based on a complex lithium aluminosilicate glass. The enamel was applied using a vitreous enamelling coating technique, followed by conversion to a glass-ceramic. The coating process strongly influenced the microstructural form developed. For both metal substrate types it was possible to produce coatings which wet well and exhibit good adhesion. Crystalline substrate oxide is observed at the interfaces of these coatings. Abrasion prior to preoxidation is an essential requirement for good coating adhesion on a chrome-iron substrate. The interface region for a coating on chrome-iron exhibits little interaction or microstructural change. -However the coating on mild steel exhibits extensive interaction, with a reaction zone extending into the coating. The marked difference between the two coated substrate types can be explained by the different substrate oxide formed, solubility of the substrate oxide in the coating and nucleating ability of the substrate oxide surface. Addition of adherence oxides (NiO, CoO) to the coating on mild steel was examined. The adherence oxides participate in complex reactions which result in the formation of metallic alloys adjacent the interface. Both adherence oxides promote wetting under conditions where wetting is not possible if they are absent. Nickel oxide is detremental to coating adhesion. This may be related to its ability to cause a rapid dissolution of iron oxide present at the interface.
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Howell, Dickson. "Dynamic testing of antifouling coatings". Thesis, University of Newcastle Upon Tyne, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437978.
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Henderson, Philip Simon. "Durable optical coatings on glass". Thesis, University of Salford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395663.
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Tinsley, Anne Margaret. "Surface coatings for molecular sensors". Thesis, Open University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358071.
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Benjamin, Susan. "Aspects of self stratifying coatings". Thesis, City University London, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360786.
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Al-Aaraji, Mohammed. "Nanostructured ferroelectric ceramics and coatings". Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/nanostructured-ferroelectric-ceramics-and-coatings(fee6c466-fce3-40f1-806a-2f26ecacdf82).html.
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Lead-based and lead-free ferroelectric ceramic materials were prepared at low sintering temperatures with particular regard to their applications in thick film piezoelectric components. This project is focused on the development of processing methods and novel compositions to be used for thick film production by electrophoretic deposition (EPD) on heat-resistant alloys. Lead-based glasses and an oxide mixture (LiCO3, Bi2O3 and CuO), denoted LBCu, with low melting points were used as sintering aids for lanthanum-doped lead zirconate titanate (PLZT) ceramics. The required temperature to achieve dense ceramics was reduced from 1250 to 950 °C. It was found that the highest ferroelectric properties were obtained by the use of LBCu in comparison with those incorporating glass additives due to the shielding effect of the glass phase between the ferroelectric grains. However, the results of thick film preparation shown that the samples with glass additives were much smoother and relatively free of cracks up to 1000 ÂoC. In terms of lead-free ceramics, novel compositions were prepared, based on (Ba,Ca)(Zr,Ti)O3-(K0.5Bi0.5)TiO3 (BCZT-KBT) solid solutions having various Ca and Zr contents. The new solid solutions exhibited interesting features comprising core-shell type microstructures and relaxor ferroelectric behaviour in addition to reduced sintering temperatures and higher Curie point compared with BCZT ceramics. The required sintering temperature reduced to 1125 °C at 65% KBT, in comparison with 1500 °C for pure BCZT. The results showed that the compositional heterogeneity in the shell regions was reduced by air quenching, relative to that of the slow-cooled state, due to the retention of the more chemically-homogeneous high temperature state by the quenching process. The improvements were evident in increased polarisation, piezoelectric coefficient and depolarisation temperature values. However, the slow-cooled samples exhibited high reversible strain levels due to the presence of polar nanoregions (PNRs) in the ergodic state within the shell regions. Comparing the results obtained for two BCZT compositions, it was demonstrated that the stability of the ferroelectric tetragonal phase in slow-cooled BCZT-KBT samples was improved for the ceramic with lower Ca and Zr concentrations, denoted x=0.06, in comparison with that for higher levels, denoted x=0.15. Moreover, the electric field-induced ferroelectric state in the quenched ceramic with x=0.06 was found to be more stable during heating, giving rise to an enhanced depolarisation temperature.
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Dempster, William. "Glass coatings for automobile applications". Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/18131/.
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Cloete, William Joseph. "Development of permanently antimicrobial coatings". Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/17945.
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Thesis (MSc)--Stellenbosch University, 2011.ENGLISH ABSTRACT: Water-borne coatings often contain multiple additives including pigments, dispersing agents, rheology modifiers, UV stabilizers and biocides. Due to their low molar mass and endocrinedisrupting properties, many of these additives, upon leaching from the substrate film, with time pollute water systems and become hazardous to the environment and to human health. In this study, I aimed to develop a facile method for the production of a polymeric biocide to serve as alternative to low molar mass biocides used in water-borne coatings. A secondary aim was to show that, without additional modification, the polymeric species can be used in surfactant-free ab initio emulsion polymerizations. Using a two-step process, I modified a commercially available copolymer, poly(styrene-alt-maleic anhydride) (SMA 1000), with mixed amines in order to obtain latexes with inherent antimicrobial activity. In the first step, I reacted SMA 1000 with 3-dimethylamino-1-propylamine and aqueous ammonia to confer antimicrobial activity and water-solubility to the SMA copolymer. In the second step, the copolymer was incorporated into a film-forming styrene-butyl acrylate (STY/BuA) latex. The modified SMA was incorporated into a latex in two ways: (1) post-added to the latex, and (2) used as stabilizer in emulsion polymerization. In both cases, the latex remained stable for up to 11 months, and stability was probably due to steric stabilization of the polymer particles. Antimicrobial activity of the latex film was achieved with both methods. When the modified SMA was post-added, antimicrobial activity was restricted to specific areas on the eventual polymer film, and when modified SMA was used as stabilizer, antimicrobial activity was evenly distributed throughout the polymer film. Fluorescence microscopy showed homogeneous distribution of antimicrobial activity upon inoculation in Gram positive bacteria dispersions when the modified copolymer was used as polymeric stabilizer for the synthesis of STY/BuA latexes. No antimicrobial activity against Gram negative bacteria was achieved. The homogeneous distribution of antimicrobial activity throughout the film was a result of adsorption of polymeric biocide/stabilizer to each individual latex particle. With further commercial development, high molar mass copolymers modified for antimicrobial activity may be a feasible, environmentally-friendly and healthy alternative to be used as stabilizers in emulsion polymerizations to produce water-borne coatings.
AFRIKAANSE OPSOMMING: Waterverf bestaan gewoonlik uit ‘n verskeidenheid bestandele, onder andere: pigmente, verspreiding middels, reologie modifiseerders, UV stabiliseerders en biologies aktiewe verbindings. As gevolg van die lae molêre massa en die endokrien ontwrigtende vermoë van baie van die bestandele hou hulle ‘n bedreiging in vir die omgewing in terme van waterbesoedeling en menslike gesondheid, soos hulle die film oor tyd verlaat. In hierdie studie het ek beoog om ‘n eenvoudige metode vir die vervaardiging van ‘n polimeries biologies aktiewe verbindings daar te stel om sodoende as ‘n alternatief vir die lae molêre massa biologies aktiewe verbindings, wat tans in waterverf gebruik word, te dien. ‘n Sekondêre uitkoms van die studie was om te wys dat, sonder enige adissionele omskakelings, dieselfde polimeer gebruik kan word in seep-vrye emulsie polimerisasie. Deur gebruik te maak van ‘n proses, wat uit twee stappe bestaan, het ek ‘n kommersieel beskikbare kopolimeer, poly(stireen-alt-maleinesuuranhidried) (SMA 1000), met gemengde amiene reageer om ‘n sintetiese lateks van stireen en butiel akrilaat (STY/BuA) met inherente antibakteriële aktiwiteit te verkry. In die eerste stap is SMA 1000 met 3-dimetielamien-1-propielamien en waterige ammoniak reageer om ‘n water oplosbare kopolimeer met inherente anti-bakteriële aktiwiteit te verkry. In die tweede stap is hierdie kopolimeer by ‘n sintetiese lateks gevoeg op twee maniere: (1) deur dit nadat die lateks geproduseer is by te voeg, en (2) deur die kopolimeer as stabiliseerder te gebruik in die vervaardiging van die lateks. In albei gevalle is stabiele latekse verkry vir ‘n tydperk van tot 11 maande. Die stabilisering was van steriese geaardheid. Albei die latekse het gevolglik antibakteriële eienskappe getoon. Daar was nie homogene verspreiding van die aktiwiteit in die geval waar die kopolimeer na die tyd bygevoeg is nie en het veroorsaak dat daar sekere areas van die finale film was wat geen aktiwiteit getoon het nie. Fluoresensie mikroskopie het egter homegene verspreiding van die anti-bakteriële aktiwiteit reg deur die film getoon, na inokulasie met Gram positiewe bakterië suspensies wanneer die kopolimeer as polimerisasie stabiliseerder gebruik was. Geen aktiwiteit teen Gram negatiewe bakterië was egter verkry nie. Die homogene verspreiding was as gevolg van die feit dat die kopolimeer sterk adsorbeer op elke individuele lateks partikel wanneer dit as stabiliseerder gebruik word. Verdere ontwikkeling op ‘n kommersiële basis kan daartoe lei dat polimeries biologies aktiewe verbindings as ‘n lewensvatbare en omgewingsvriendelike alternatief vir heidige stabiliseerders in emulsies vir waterverf gebruik kan word.
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Seboa, Sharrief. "Polyurethane dispersions for paper coatings". Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/53005.
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Thesis (MSc)--Stellenbosch University, 2002.ENGLISH ABSTRACT: Aqueous polyurethane (PU) dispersions were synthesized for the use in paper coatings. These PUs contained a polyester polyol soft segment (content of 60-70%) and a urethane hard segment (content of 30-40%). This was followed by grafting using four different grafting agents. Triethylamine (TEA) was used as the neutralizing agent. The polyester polyol segment consisted of neopentyl glycol (NPG), adipic acid, 1,4-cyclohexane dicarboxylic acid (1,4-CHOCA) and 2-phosphonobutane-1 ,2,4- tricarboxylic acid (PSTCA), while the urethane hard segment consisted of hydrogenated 4,4-diphenylmethane diisocyanate, dimethylolproponic acid (OMPA), 3-hydroxypivalic acid (HPA) and hydroxyethylene methacrylate (HEMA). The grafting agents used were lauryl methacrylate (LMA), n-butyl methacrylate (n-SMA), methyl methacrylate (MMA) and styrene. Two different polyester polyols were synthesized, one containing 10% phosphate and the other none. The polyols were characterized in terms of their acid value, hydroxyl value and molecular mass. The PUs synthesized from the polyol containing 0% phosphate were grafted with LMA, while the phosphate-containing PUs were grafted with each of the all four grafting agents. The resulting dispersions were applied to paperboard, and then dried at a maximum temperature of 100°C. The PU-coated paperboard was characterized using the moisture vapour transmission rate (MVTR), and scanning electron microscopy (SEM) techniques. PU films (not supported by paper, stand alone) were prepared by heating the PU dispersion in Teflon holders up to 130°C for 6 hours. The dried films were then characterized by thermogravimatric analysis (TGA), differential scanning calorimetry (OSC), dynamic mechanical analysis (OMA) and Fourier transform infrared spectroscopy (FTIR). MVTR-analysis showed that the phosphated PU coatings had a minimum MVTR-value at 0% grafting, and that its overall MVTR-values were much lower than that of the non-phosphated PU coatings. SEM-analysis showed that the phosphated PU coatings had no pinholes at a maximum of 8% grafting, while the non-phosphated PU coatings showed pinholes at all levels of grafting. OMA-analysis showed that the phosphated PU samples had higher Tg's (Tg onset between O-S°C)than that of the non-phosphated PU samples (Tgonset below -SO°C).
AFRIKAANSE OPSOMMING: POLI-URETAAN DISPERSIES VIR PAPIER BEDEKKINGS Waterige poli-uretaan (PU) dispersies is gesintetiseer vir gebruik as papierbedekkings. Hierdie poli-uretane het 'n poliester poli-ol sagte segment (60-70% inhoud) en 'n uretaan harde segment (30-40% inhoud) bevat. Die poli-uretane is met vier verskillende ent-middels geêent. Trietielamien (TEA) is as neutraliseermiddel gebruik. Die poli-ester poli-ot segment het bestaan uit: neopentielglikol (NPG), adipiensuur, 1,4-sikloheksaandikarboksielssuur (1,4- SHDKS) en 2-fosfonobutaan-1 ,2,4-trikarboksielssuur (FSTKS). Die uretaan harde segment het bestaan uit: hidrogeneerde 4,4-difenielmetaandiisosianaat, dimetielpropioonsuur (DMPS), 3-hidroksipivaalsuur (HPS) en hidroksietileenmetakrilaat (HEMA). Laurielmetakrilaat (LMA), n-butielmetakrilaat (n-SMA), metielmetakrilaat (MMA) en stireen is as entmiddels gebruik. Twee verskillende poli-ester polihidroksie verbindings is gesintetiseer: een met 10% fosfaat en een met geen fosfaat, en gekarakteriseer in terme van hulle suurwaardes, hidroksiwaardes en molekulêre massas. Die PUs wat vanaf die fosfaat-bevattende poli-ol gesintetiseer is, is met LMA geêent, terwyl die fosfaat-bevattende PUs met al vier entmiddels geêent is. Papier (Eng. paperboard) is met hierdie dispersies bedek en by 100°C gedroog. Die PU-bedekte papier is gekarakteriseer in terme van vogdeurlaatbaarheidstransmissie (Eng: MVTR - the moisture vapour transmission rate), en skandeerelektonmikroskopie (SEM). PU-films wat nie deur papier gestut is nie is ook voorberei deur die verhitting van die PU dispersies in Teflon houers (130°C, 6 ure). Die droë films is daarna gekarakteriseer deur middel van termogravimetriese analise (TGA), differensiêle skandeerkalorimetrie (DSC), dinamiese meganiese analise (OMA) en Fourier-transformasie infrarooispektroskopie (FTIR). Resultate van MVTR analises het getoon dat die fosfaat-bevattende PU bedekkings 'n mimimum MVTR-waarde by 0% enting gehad het, en dat die totale MVTR waardes baie laer was as die van die nie-fosfaatbevattende bedekkings. SEM het gewys dat die fosfaat-PU bedekkings by 8% enting geen mikrogaatjies (Eng. pinholes) gehad net nie, terwyl die PU bedekings met geen fosfaat mikrogaatjies (Eng. pinholes) by alle vlakke van enting gehad het. OMA analises het getoon dat die monsters van die fosfaatbevattende PU hoër Tg waardes gehad het (Tg begin tussen 0 en 5 "C) as die nie-fosfaatbevattende PU monsters (Tg begin onder -50°C).
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Vennard, Ashlene S. M. "Photocatalytic coatings for medical applications". Thesis, Ulster University, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.625500.
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Medical equipment and environmental surfaces can provide a source of infection if not disinfected properly and contribute to the transmission of healthcare associated infection (HCAI). To help combat the problem of HCAI photocatalytically active titanium dioxide (Ti02) coatings could be used. The coatings have a self-cleaning effect and when activated by light of appropriate wavelength generate reactive oxygen species that can inactivate pathogenic micro-organisms. More recent work in photocatalytic disinfection has centred on the use of doped-Ti02 coatings which could be activated by ambient indoor light without the need for UV sources. In this work a range of metal and non-metal doped Ti02 coatings were characterised and assessed for their anti-bacterial ability for use as potential coatings for environmental surfaces. All films showed the presence of anatase, the most photocatalytically active form of Ti02, however some of the films did not show the presence of the dopant, possibly due to concentration being below XPS detection limit. In disinfection testing, most of the films did not exhibit visible light activated photocatalytic disinfection towards E. coli. Aside from the Ag-Ti02 film which, after 6 h visible light irradiation, did show slightly better inactivation of bacteria when compared to the light control. The only film to reduce bacteria considerably was S-Ti02 after 1.5 h irradiation; however this film also inactivated bacteria in the dark therefore the activity of S-Ti02 was likely due to sulphur radicals and probably not a photocatalytic affect however further investigation into inactivation mechanism is needed. These findings suggest that doped-Ti02 films activated by visible light lacked a photocatalytic affect and would not be beneficial as self-disinfecting surfaces. Ti02 films were then created via sputter deposition. To gain anatase phase a range of power settings and gas settings were varied until finally increasing the gas pressure resulted in anatase formation instead of rutile. The films were tested for their bactericidal ability but showed no enhanced killing when compared to the UVA light. It was thought the planar surface of the sputtered coatings had a low surface area therefore' reducing their photocatalytic disinfecting ability. However the films produced did show potential photocatalytic activity due to an increase in hydrophilicity of the surface after UVA irradiation. Finally anatase Ti02 was sputtered onto Poly methyl methacrylate (PMMA) and assessed for UVC protection, increased hardness and disinfection properties under UVC irradiation. The coating prevented the degradation of the polymer under UVC irradiation and therefore would allow for rapid UVC disinfection of PMMA medical devices to prevent transmission of infection. UVC disinfection studies on the Ti02 coated PMMA showed complete inactivation of E. coli after 10 s and complete inactivation of Fusarium solani spores in 5 min. Hardness and Young's modulus testing showed that both parameters were slightly enhanced with the addition of the Ti02 coating which may increase wear resistance. Therefore, Ti02 coatings could be used as a protective coating for polymers used in medical devices and allow UVC disinfection of these devices to reduce the risk of infection.
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Rhodes, Jennifer. "Fire protection of surface coatings". Thesis, University of Central Lancashire, 2012. http://clok.uclan.ac.uk/3738/.
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Multilayer paint is a significant fire hazard particularly concerning rapid spread of flame,smoke and toxic species production. Fire protective coatings are often employed to protect this unpredictably flammable substrate from ignition (for example resulting from arson attacks in the communal areas of multi- occupancy buildings). Literature shows a gap in the understanding of this problem,a lack of suitable flammability tests,and methods for screening new fire protective coatings required to address this problem. This work investigates the factors affecting coating performance and develops screening test methods to estimate protection performance in standard fire tests. The dependence of these tests has been investigated with regard to substrate, coating thickness,composition of coating, thermal conductivity and rheological properties, to inform the development of modified coating formulations with enhanced fire safety.Coating materials have been investigated using thermogravimetric ana lysis (TGA) in both air and inert atmospheres and their burning behaviour using the cone calorimeter (ISO 5660). Novel screening test methods also include a test adapted from BS EN 367 for measurement of thermal conductivity, a thermocouple embedded in cone samples to assess the temperature profile at the substrate-coating interface and BS 476: Part 6 (adapted) as a scaled down version of the standard fire test. The chemical changes occurring during burning of current coatings formulations were investigated using CHN analysis, pyrolysis gas chromatography coupled with mass spectrometry (pyGC-MS),inductively coupled plasma coupled with mass spectrometry (ICP-MS),diamond attenuated total reflectance coupled with fourier transform infra-red (dATR-FTIR),nuclear magnetic resonance (NMR} and scanning electron microscopy coupled with electron dispersive X-ray analysis (SEM-EDAX} to inform the development of novel formulations. Generally,intumescent formulations tend to exhibit lower fire propagation indexes when assessed in the BS 476: Part 6,longer time to ignition and lower peak heat release rates in the cone calorimeter, as well as reduced thermal conductivity recorded in the BS EN 367. Results report mixed performance,suggesting that it is not only char residue formation that ensures a pass in the standard fire tests. Rheological properties of the coatings are crucial to performance,with softening temperature and reduction in viscosity coinciding with gas release of the fire retardant additive. Each screening test method assesses one particular aspect of flammability, they are dependent on the controlled conditions under which results are collected,and the limited correlation observed with the performance in the standard fire tests, do not conclusively predict performance in a real fire situation.
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Frodelius, Jenny. "Thick and Thin Ti2AlC Coatings". Doctoral thesis, Linköpings universitet, Tunnfilmsfysik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-57525.
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This Thesis explores the deposition techniques of magnetron sputtering and high velocity oxy-fuel (HVOF) spraying for Ti2AlC as a promising high-temperature material. Magnetron sputtering aims at producing thin (≤1 μm) Ti2AlC films of high crystal quality for use as a model system in understanding the material’s basic properties. HVOF is a new method for deposition of thick (≥200 μm) coatings by spraying Ti2AlC powder, with the aim of transferring the good bulk properties to coatings. The oxidation behavior of Ti2AlC coatings has been investigated for temperatures up to 1200 °C in air. As-deposited Ti2AlC(0001) thin films decompose into TiC during vacuum annealing at 700 °C by out-diffusion of Al as shown by x-ray diffraction analysis. The release of Al starts already at 500 °C in ambient air as driven by aluminum oxide formation on the film surface where the oxide initially forms clusters as observed by electron microscopy. While sputtering from a Ti2AlC target is simpler than by using different elemental targets, the resulting film composition differs from the target stoichiometry. This is due to differences in energy and angular distribution of the sputtered species and evaporation of Al at substrate temperatures above 700 °C. The composition can be compensated for by adding Ti to bind the Al and obtain phase-pure Ti2AlC coatings. For HVOF, I demonstrate how the total gas flow of a H2/O2 mixture (441-953 liter/min) and the powder grain size (30-56 μm) determine the thickness, density, and microstructure of the coatings. High gas flow and small grain size yield thick coatings of 210 μm with a low porosity of 2-8 % and a tensile stress of ≥80 MPa. A fraction of the Ti2AlC powder decomposes during spraying into TiC, Ti3AlC2, and Ti-Al alloys. The coatings also contain as much as 25 at.% O since the powder partly oxidizes during the spraying process. Increasing the powder size and decreasing the total gas flow yield a higher amount of Ti2AlC, but produces thinner coatings with lower cohesion. Post-annealing of the coatings at 900 °C in vacuum increases the Ti2AlC content due to a reversible phase transformation of the as-sprayed material. The high oxygen content, however, hinders the coating to completely transform into Ti2AlC and deteriorates its oxidation resistance. The work thus offers insights to the key parameters for optimizing Ti2AlC coating processing.
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Tsui, Yun Cheong. "Adhesion of plasma sprayed coatings". Thesis, University of Cambridge, 1996. https://www.repository.cam.ac.uk/handle/1810/283710.
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Popa, Gabriela. "Spray-on hybrid nanoscale coatings". Strasbourg, 2010. https://publication-theses.unistra.fr/public/theses_doctorat/2010/POPA_Gabriela_2010.pdf.
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Des couches minces hybrides ont été préparé par une version modifiée de la méthode classique de déposition « couches-par-couches ». Les couches inorganiques de ces films hybrides sont déposés en utilisant la méthode de pulvérisation consécutive (qui est la méthode modifiée) pour laquelle la pulvérisation de solutions aqueuses se fait de manière alterné avec des temps de pulvérisation très courts (moins de 5 secondes). Nombreuses couches inorganique sont obtenues par cette technique telles que des couches de phosphate de calcium, oxalate de calcium, fluorure de calcium, Blue de Prusse, chlorure d’argent, etc. L’application principale des couches hybrides contenant de phosphate de calcium et Collagène est la fabrication de nouveaux biomatériaux pour la régénération/réparation du cartilage articulaire (le domaine d’ingénierie tissulaire). La structure de type « sandwich » de ces components permet la mimique du cartilage articulaire naturel. Pour la préparation de ces couches hybrides on a utilisé un film mince de polyélectrolytes de (PAHPSS). Le dépôt de couche mince inorganique peut se faire aussi en utilisant la méthode de pulvérisation simultanée des deux solutions contenant les cations et les anions. Des couches minces homogènes sur des surfaces d’ordre des cm2 ont été obtenues et pour lesquelles l’épaisseur peut être contrôlée par la variation de paramètres de pulvérisation tels que le temps de pulvérisation, la concentration de la solution, la nature du substratHybrid thin films were prepared by a modified variant of the classical Layer-by-Layer (LbL) deposition method. Inorganic coatings are deposited using the consecutive spray method, in which aqueous solutions are alternatingly sprayed for short times (less than 5 seconds). Numerous inorganic coatings were prepared this way such as calcium phosphate, calcium fluoride, calcium oxalate, silver chloride, Prussian Blue. The main target of the hybrid films comprised of calcium phosphate and Collagen is for application in the cartilage repair. “Sandwich”-like structures of these components mimic the natural articular cartilage structure. In order to obtain the hybrid film containing Collagen and calcium phosphate, we used a (PAHPSS)barrier film. The deposition of inorganic coating can also be realized using the simultaneous spraying method where both solutions (cationic and anionic solution) are sprayed simultaneously. Homogeneous on several cm2 of surface thin films are obtained in which the film thickness is controlled by spray parameters such as spraying time, solution concentration, nature of substrate to be coated
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Moore, Kevin Charles. "DEPOSITION OF COATINGS ONTO NANOFIBERS". University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1153749172.
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Wang, Xiaojiang. "Polyester Based Hybrid Organic Coatings". University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1340906197.
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Gao, Tongzhai. "Anticorrosive Organic/Inorganic Hybrid Coatings". University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1412775013.
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Izzard, Michael. "Autocatalytic deposition of composite coatings". Thesis, Aston University, 1987. http://publications.aston.ac.uk/11907/.
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The deposition and properties of electroless nickel composite coatings containing graphite, PTFE and chromium were investigated. Solutions were developed for the codeposition of graphite and chromium with electroless nickel. Solutions for the deposition of graphite contained heavy metal ions for stability, with non-ionic and anionic surfactants to provide wetting and dispersion of the particles. Stability for the codeposition of chromium particles was achieved by oxidation of the chromium. Thin oxide layers of 200 nm thick prevented initiation of the electroless reaction onto the chromium. A mechanism for the formation of electroless composite coatings was considered based on the physical adsorption of particles and as a function of the adsorption of charged surfactants and metal cations from solution. The influence of variables such as particle concentration in solution, particle size, temperature, pH, and agitation on the volume percentage of particles codeposited was studied. The volume percentage of graphite codeposited was found to increase with concentration in solution and playing rate. An increase in particle size and agitation reduced the volume percentage codeposited. The hardness of nickel-graphite deposits was found to decrease with graphite content in the as-deposited and heat treated condition. The frictional and wear properties of electroless nickel-graphite were studied and compared to those of electroless nickel-PTFE. The self-lubricating nature of both coatings was found to be dependent on the ratio of coated area to uncoated area, the size and content of lubricating material in the deposit, and the load between contacting surfaces. The mechanism of self-lubrication was considered, concluding that graphite only produced an initial lubricating surface due to the orientation of flakes, unlike PTFE, which produced true self-lubrication throughout the coating life. Heat treatment of electroless nickel chromium deposits at 850oC for 8 and 16 hours produced nickel-iron-chromium alloy deposits with a phosphorus rich surface of high hardness. Coefficients of friction and wear rates were intially moderate for the phosphorus rich layer but increased for the nickel-iron-chromium region of the coating.
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Jota, Thiago, i Thiago Jota. "Polarization Aberrations of Optical Coatings". Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/624138.
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This work does not limit itself to its title and touches on a number of related topics beyond it. Starting with the title, Polarization Aberrations of Optical Coatings, the immediate question that comes to mind is: what coatings? All coatings? Not all coatings, but just enough that a third person could take this information and apply it anywhere: to all coatings. The computational work-flow required to break-down the aberrations caused by polarizing events (3D vector forms of reflection and refraction) in dielectric and absorbing materials and for thick and thin films is presented. Therefore, it is completely general and of interest to the wide optics community.
The example system is a Ritchey-Chrétien telescope. It looks very similar to a Cassegrain, but it is not. It has hyperbolic surfaces, which allows for more optical aberration corrections. A few modern systems that use this configuration are the Hubble Space Telescope and the Keck telescopes. This particular system is a follow-up on this publication, where an example Cassegrain with aluminum coatings is characterized, and I was asked to simply evaluate it at another wavelength. To my surprise, I found a number of issues which lead me to write a completely new, one-of-its-kind 3D polarization ray-tracing code. It can do purely geometrical ray-tracing with add-on the polarization analysis capability, and more importantly: it keeps your data at your fingertips while offering all the outstanding facilities of Mathematica. The ray-tracing code and its extensive library, which can do several advanced computations, is documented in the appendix.
The coatings of the Ritchey-Chrétien induce a number of aberrations, primarily, but not limited to: tilt, defocus, astigmatism, and coma. I found those forms to exist in both aluminum and with a reflectance-enhancing dielectric quarter-wave multilayer coating over aluminum. The thickness of the film stack varies as function of position to present a quarter-wave of optical thickness to oblique rays. Most commercial optical software that I know cannot compute this. And the results are impressive: the scalar transmission, which is a measure of ray efficiency, was raised from 78% to 95%. This means that only 5% of the incident light is lost, assuming ideal coating interfaces. This is very advantageous, considering the application: coronagraphs for exoplanet detection. Exoplanets are very far away, and therefore efficient use of light is essential.
I also created a ray! I call it Huygens' twin ray. It is credited to Christiaan Huygens, who postulated that points on a wavefront can be considered as a sources of secondary spherical wavelets. This concept normally belongs to physical optics. The twin ray is emitted from the exact same object point but traced in a slightly different direction, which can be assumed by invoking Huygens's principle, and defined in a special way that consistently prevents vignetting. This requires high-precision ray-tracing, which is introduced along with this thesis work as part of the appendix. The application of this concept is exemplified in finding the exit pupil of the Ritchey-Chrétien telescope. It can be modified to work in a plurality of cases and find the precise image location in three-dimensions, making it completely general and useful.
Mastering the ray-tracing documented here depends on how much optics the user knows, but tracing a single ray is something that can be learned in minutes. I welcome you to freely use it and make it your own. If your goal is to learn to ray-trace in Mathematica, the reader is directed to the appendix, especially to the four-port polarimeter example, as it is a 3D system that contains both reflection and refraction through thin films, thick films, retarders, and a single surface is traced at a time!