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Tesi sul tema "Protective coatings"
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1
Johnson, Brian W. "Ion transport through protective polymer coatings". Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293683.
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2
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.
Testo completoAbstract (sommario):
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.
3
Wright, J. D. "Impedance studies of water based protective coatings". Thesis, University of Newcastle Upon Tyne, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386702.
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4
Wakeham, Steve. "Protective, antireflection coatings for multispectral zinc sulphide". Thesis, University of Reading, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402630.
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5
D'ISANTO, FABIANA. "New oxidation protective coatings for thermoelectric materials". Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2839858.
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6
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.
7
Vyawahare, Siddharth M. Ahmed Ikram. "Protective thermal spray coatings for polymer matrix composites". Diss., A link to full text of this thesis in SOAR, 2006. http://soar.wichita.edu/dspace/handle/10057/684.
Testo completoAbstract (sommario):
Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering."December 2006." Title from PDF title page (viewed on Sept. 18, 2007). Thesis adviser: Ikram Ahmed. Includes bibliographic references (leaves 79-81).
8
Shen, Hao. "A study of active fillers in protective coatings". Thesis, University of Essex, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304467.
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9
Close, Damien. "Alternative protective coatings for hot stamped automotive body parts". Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0083/document.
Testo completoAbstract (sommario):
De nombreux revêtements sont actuellement disponibles pour les aciers emboutis à chaud et trempés pour le domaine de la construction automobile. Afin d’augmenter les performances des produits actuels en termes d’aptitude à la mise en forme à chaud, de résistance contre la corrosion et de compatibilité avec les procédés de fabrication ultérieurs, les constructeurs automobiles et les sidérurgistes ont développé de nombreux types de matériaux alternatifs. Peu de produits ont trouvé une place importante dans l’utilisation industrielle. L’objectif de ce travail est de procéder à une vue d’ensemble des performances des produits actuels, d’identifier de nouveaux concepts de revêtements et d’étudier leur compatibilité pour l’application de la mise en forme à chaud. Cette étude porte sur les revêtements d’alliages de Zn-Mn. De nombreux bains électrolytiques et paramètres électriques ont été étudiés afin de déterminer des conditions de déposition optimales pour obtenir des alliages Zn-Mn avec une forte teneur en Mn. Les propriétés cristallographiques, microstructurales et anticorrosives de couches obtenues sur des plaques d’acier de grandes dimensions ont été caractérisées avec de nombreuses techniques. La compatibilité des couches protectrices pour le traitement d’austénitisation a été évaluée après des traitements thermiques à différentes températures et durées de chauffe. Une attention particulière a été portée sur l’évolution de la composition et des phases d’interdiffusion formées, ainsi que sur l’apparition de mécanismes d’oxydation et d’évaporation à haute température. Enfin, l’aptitude à la mise en forme à chaud et notamment la susceptibilité à la fissuration par métaux liquides de ces nouveaux revêtements ont été évaluées par des essais d’emboutissageVarious coatings are currently available for press-hardened steels used for the automotive construction, mainly with the aim of providing good anticorrosive properties to the body components. In order to improve performance of the coated products in terms of hot formability, corrosion protection and suitability for subsequent manufacturing processes, steelmakers and car manufacturers investigated various alternative coating materials. Only a few solutions resulted in a serial production. The aim of this study is to proceed to a screening of the performance of current coating variants, to identify new concepts for alternative coating materials and assess their suitability for the hot stamping application. The present work is focused on the study of Zn-Mn alloy coatings. Various electroplating baths and electric parameters were studied in order to determine optimal deposition conditions for obtaining Zn-Mn alloys with high Mn contents. The deposits obtained on large-scale steel plates were characterized with regards to their crystallographic, microstructural and anticorrosive properties. The behavior of the coating materials during austenitizing treatment was studied after heat treatment to different temperatures and heating durations. A particular attention was given to the evolution of the composition, the interdiffusion phases formed as well as to the presence of oxidation and evaporation mechanisms at high temperature. At last, the forming properties of the alternative coating materials and their susceptibility for liquid metal embrittlement were assessed on the basis of direct hot stamping experiments
10
Geromel, Prette Andre Luiz. "Sintering of Co2MnO4 spinel for protective coatings in SOFC". Doctoral thesis, Università degli studi di Trento, 2011. https://hdl.handle.net/11572/367848.
Testo completoAbstract (sommario):
Protective coatings are often deposited on SOFC interconnectors to avoid poisoning of cathode from chromium species that evaporate from stainless steel interconnects or supports. Co2MnO4 spinel compounds are usually considered as the main constituent of protection barriers. Nevertheless, such ceramic sinters at high temperatures (>1200°C) and this can be problematic for the properties of the stainless steel components. One of the major issues is, in fact, the creation of a compact and impermeable coating at relatively low temperature in order to preserve the metal substrate. In the present research work, Co2MnO4 spinel was synthesized by various methods (solid-state, gel-combustion, co-precipitation and reverse micelle) and the obtained specific surface area, structure and particle size were correlated with thermal behaviour, sintering temperature and achieved density. It was found that regardless the synthesis process the only obtained phase is Co2MnO4. Specific surface area from 0,8 to 65 m2g-1 was obtained, depending on the synthesis method.
Sintering aids such as Nb2O5 and LiF were used to obtain dense microstructure at relatively low temperature. Considerable changes in sintering temperature were observed this being even 100-200ºC lower than that necessary for the consolidation of pure spinel though microstructure with only close pores was achieved.
A novel sintering method based on Field Assisted Techniques (FAST) that promoted flash-sintering phenomenon was finally applied to Co2MnO4. Small electric field (<7,5 V cm-1) applied to the spinel decreases the sintering temperature down to 600°C. The application of an electric field above 7,5 V cm-1 flash-sintering phenomenon takes place and sintering temperature drops to about 300°C, the sintering time being less than 1 second.
11
Geromel, Prette Andre Luiz. "Sintering of Co2MnO4 spinel for protective coatings in SOFC". Doctoral thesis, University of Trento, 2011. http://eprints-phd.biblio.unitn.it/542/1/Prette_Tesi_PhD_PDF.pdf.
Testo completoAbstract (sommario):
Protective coatings are often deposited on SOFC interconnectors to avoid poisoning of cathode from chromium species that evaporate from stainless steel interconnects or supports. Co2MnO4 spinel compounds are usually considered as the main constituent of protection barriers. Nevertheless, such ceramic sinters at high temperatures (>1200°C) and this can be problematic for the properties of the stainless steel components. One of the major issues is, in fact, the creation of a compact and impermeable coating at relatively low temperature in order to preserve the metal substrate. In the present research work, Co2MnO4 spinel was synthesized by various methods (solid-state, gel-combustion, co-precipitation and reverse micelle) and the obtained specific surface area, structure and particle size were correlated with thermal behaviour, sintering temperature and achieved density. It was found that regardless the synthesis process the only obtained phase is Co2MnO4. Specific surface area from 0,8 to 65 m2g-1 was obtained, depending on the synthesis method.
Sintering aids such as Nb2O5 and LiF were used to obtain dense microstructure at relatively low temperature. Considerable changes in sintering temperature were observed this being even 100-200ºC lower than that necessary for the consolidation of pure spinel though microstructure with only close pores was achieved.
A novel sintering method based on Field Assisted Techniques (FAST) that promoted flash-sintering phenomenon was finally applied to Co2MnO4. Small electric field (<7,5 V cm-1) applied to the spinel decreases the sintering temperature down to 600°C. The application of an electric field above 7,5 V cm-1 flash-sintering phenomenon takes place and sintering temperature drops to about 300°C, the sintering time being less than 1 second.
12
Du, Plessis Maximilian. "Sensitivity analysis of EB-PVD thermal barrier coatings for aerospace applications". Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/1289.
Testo completoAbstract (sommario):
Dissertation
Master of Technology
Mechanical Engineering
Faculty of Engineering
Cape Peninsula University of Technology
2014Thermal Barrier Coatings (TBC’s) created by Electron Beam Physical Vapour Deposition (EB-PVD) are widely used in the aerospace industry. Advancements in the field however are hindered by the cost and time required for research and development. Hence, there exists a need for a more comprehensive understanding of coating parameter interactions to better predict response values without the need for extensive pre-production testing. This thesis seeks to provide a response surface for EB-PVD coatings, by investigating the following EB- PVD independent input variables: electron beam emission current, gas ratio, vacuum pressure, substrate temperature, roughness and process time in order to generate a predictive statistical model. Output variables were numerous, however emphasis was placed on: TBC coating thickness and density of columns generated during the process. It is impossible to select an “optimum process recipe”; rather, there exists many optimal combinations suited to specific coating structure and its application. Therein lies the need for this model, able to predict TBC properties according to input variables. Using ALD’s Smart Coater (ALD Vacuum Technologies GmbH), a ceramic top coat (Yttria partially stabilized zirconia, YPSZ, ZrO2-7%Y2O3) was deposited onto 40x30x5mm Inconel 617 samples with NiAl bond coat. These samples were subsequently tested to determine coating properties. The research will show that the complex nature of EB-PVD TBCs may be simplified, at least to a certain degree through a statistical analysis of the interactions between process variables.
13
Whitehead, David James. "Pulsed laser interactions with protective polymer coatings of optical fibres". Thesis, University of Hull, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431050.
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Tan, Ruoyo. "Protective coatings for Al press tools used in automotive industry". Thesis, Högskolan Väst, Avd för tillverkningsprocesser, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-6858.
Testo completoAbstract (sommario):
The application of the thermally sprayed WC-Co and Cr 3C2-NiCr coatings have been widely used in industry for its superior sliding, abrasive and erosive wear properties. The Al2O3 coating possessing high hardness can be utilized to improve the wear resistance of the metallic surface. Replacing the stamping tool material from steel to lightweight aluminium with protective coatings offers significant gains such as reduction in power costs and increasing operational efficiency during manufacturing of sheet automobile parts. In this study, the WC-CoCr and Cr3C2-NiCr coatings were sprayed with High Velocity Air-Fuel (HVAF) process and Al2O3 coating was deposited using Atmosphere Plasma Spraying (APS) process. The coatings were evaluated and compared based on the results of roughness tests, hardness tests, adhesion tests, quantitative imaging analysis and microstructure analysis. The experimental results revealed that the roughness value varied in a lower range which implies of a high density of the coatings. It was found that coatings have an extremely high hardness value as tested by the Vickers hardness test. The WC-Co coating was found to be the hardest (1215.2HV). The adhesion test was implemented according to the ASTM C633-79 standard. The result showed that WC-Co and Cr3C2-NiCr coatings without a bond coat had high tensile strength, higher than the respective glue strength (63.54MPa, 75.89MPa). Whereas, the Al2O3 coating has a much lower tensile strength (15.2MPa, 25.68MPa, with and without bond) than others and using a bond coat layer does not contribute to an increase in adhesion strength of the cermet coatings. The coating thickness was evaluated using Light Optical Microscopy (LOM) and microstructure analysis was carried out using Scanning Electron Microscopy (SEM). From the microstructure analysis, it was observed that all the coatings have a dense microstructure, very low porosity and low oxide inclusions in top coat. The WC and Cr3C2 grains retain a large volume fraction of finely dispersed in matrix. The alumina coating was found to have low levels of un-melted or the re-solidified particles in the coating. All of the aforementioned analysis and results reveal that WC/CoCr and Cr3C2-NiCr coating show promising potential for press tool applications. However, abrasive resistance test still remained to be done and will be performed in the future. The result of it can reveal the actual wear resistance between two coatings in reality and will be helpful in determining the better protective coating for aluminium press tools
15
Appleby, Matthew P. "High Temperature Damage Characterization Of Ceramic Composites And Protective Coatings". University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1461932405.
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Nazemi, Mohammad Karim. "Corrosion Study of Protective Coatings Used in Sewer Concrete Pipelines". Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/16505.
Testo completoAbstract (sommario):
Microbiologically Induced Corrosion (MIC) induced by the activity of various microorganisms including bacteria and fungi is a major problem facing water and wastewater treatment utilities around the world. Different mitigation strategies are used to combat the effect of microbial corrosion. Various polymeric coatings such as epoxy and epoxy mortar are used widely for this purpose. However, their performance is variable. More rigorous specifications are therefore required in selecting appropriate coatings. This would require an understanding of how coating properties affect their ability to resist acid permeation and structural and chemical integrity of the coating after an acid attack. The aim of this study was to obtain an understanding of the interactions between the industrial epoxy A, epoxy F and epoxy Novolac coatings and organic and inorganic acids which are found in sewer environment. In addition, the experimental findings of this study were used to develop semi-empirical models for the prediction of coating service life. The gravimetric method was used to test and understand the interactions between acids and epoxy coatings, establish the changes in epoxy properties due to acid attack and to find out the subsequent effect of acid attack on future acid permeation. A range of organic and inorganic acids and varied experimental parameters were selected for this purpose. By monitoring mass uptake, swelling and reduction in hardness combined with some instrumental analysis such as FTIR, TGA and SEM the acid-epoxy interactions and changes in epoxy structure were established. The results demonstrated the deteriorating effect of acid on physical and chemical properties of the coatings. The mechanisms of epoxy deterioration resulting from acid attack were identified as plasticisation & post-polymerisation, increased hydrophilicity and salt formation. It was found that the occurrence of these phenomena during acid attack increases the acid permeation rate and contribute to higher degradation rates in epoxy coatings. Also, the empirical models developed based on experimental data successfully predicted the acid permeation depth with coefficient of determination higher than 90%.
17
Calovi, Massimo. "Effect of contribution of graphene-based filler in cataphoretic organic protective coatings". Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/284736.
Testo completoAbstract (sommario):
The thesis aims to illustrate and highlight the potential of graphene-based fillers in reinforcing organic coatings deposited by cataphoresis. Thanks to particular surface modification processes of the graphene flakes, these have been properly distributed within the polymer matrix, providing the composite coating with remarkable protective performance. The optimization of the deposition process parameters, as well as the amount of filler, also allowed to improve the mechanical and conductivity properties of the cataphoretic matrix, suggesting the possibility of realizing multifunctional coatings. Finally, these ’smart’ coatings were made by combining two deposition techniques, creating two layers with distinct purposes, containing different types of graphene-based fillers. The cataphoretic primer provided the substrate with high corrosion protection, while the spray top coat possessed high properties of electrical conductivity and resistance to abrasion phenomena. Ultimately, graphene has proven to be an excellent resource as a reinforcing filler in multifunctional organic coatings.
18
Calovi, Massimo. "Effect of contribution of graphene-based filler in cataphoretic organic protective coatings". Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/284736.
Testo completoAbstract (sommario):
The thesis aims to illustrate and highlight the potential of graphene-based fillers in reinforcing organic coatings deposited by cataphoresis. Thanks to particular surface modification processes of the graphene flakes, these have been properly distributed within the polymer matrix, providing the composite coating with remarkable protective performance. The optimization of the deposition process parameters, as well as the amount of filler, also allowed to improve the mechanical and conductivity properties of the cataphoretic matrix, suggesting the possibility of realizing multifunctional coatings. Finally, these ’smart’ coatings were made by combining two deposition techniques, creating two layers with distinct purposes, containing different types of graphene-based fillers. The cataphoretic primer provided the substrate with high corrosion protection, while the spray top coat possessed high properties of electrical conductivity and resistance to abrasion phenomena. Ultimately, graphene has proven to be an excellent resource as a reinforcing filler in multifunctional organic coatings.
19
Vaca-Cortés, Enrique. "Corrosion performance of epoxy-coated reinforcement in aggressive environments /". Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Choy, Kwang-Leong. "Chemical vapour deposition of ceramic protective coatings onto SiC monofilament fibres". Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306417.
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Young, Kevin. "Equivalent circuit modeling of TMS plasma polymer coating system on cold-rolled steel". Diss., Columbia, Mo. : University of Missouri-Columbia, 2004. http://hdl.handle.net/10355/4104.
Testo completoAbstract (sommario):
Thesis (M.S.) University of Missouri-Columbia, 2004.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (June 30, 2006). Vita. Includes bibliographical references.
22
Shi, Jun. "On thermal mismatch and thermal gradients and the failure of thermal barrier coatings". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 2.35 Mb., 123 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3221078.
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DeBenedictis, Mach Austin. "Model development for the electrostatic fluidized bed powder coating process". Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/11326.
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Yu, Ronghua. "Impedance-Based Wireless Sensor Network for Metal-Protective Coating Evaluation". Thesis, North Dakota State University, 2011. https://hdl.handle.net/10365/28837.
Testo completoAbstract (sommario):
Research has focused on the influences of flowing fluid on the corrosion of bare metals, but there is little emphasis on the degradation of metal-protective coating. Evaluating the metal-protective coating usually uses the Electrochemical Impedance Spectroscopy (EIS) method. This paper presents a new impedance-based wireless sensor network for metal-protective coating evaluation. This wireless sensor network consists of two parts: impedance-based wireless sensor nodes and a wireless data base that are equipped with a network analyzer (AD5933) and a RF transceiver (CC1111/CC1110). In the experiment, three coating panels are immersed in flowing deionized water (DI water) and one coating panel immersed in stationary DI water. Experimental results demonstrate that this wireless sensor network is capable of evaluating the coating degradation.
25
VESCO, SILVIA. "Development and characterization of functionalized protective coatings based on organosiloxane hybrid materials". Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2013. http://hdl.handle.net/2108/203502.
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Scrinzi, Erica. "Service life of organic coatings: strategies for improving aesthetic and protective durability". Doctoral thesis, Università degli studi di Trento, 2011. https://hdl.handle.net/11572/368719.
Testo completoAbstract (sommario):
It is probably needless to mention that organic coatings are of paramount importance nowadays. Although the huge number of applications and their wide spread can suggest that organic coatings have now reached a level of maturity, they are still mysterious from a certain point of view. The behaviour of these systems is not completely understood yet, especially as regarding the relationships between the chemical formulation and the manufacturing/applications technologies on one side, and the final properties on the other side. In this scenario, durability is regarded the most crucial point and finding satisfying design solutions is not straightforward.
Automotive and architecture are perhaps two of the most challenging areas where the durability is claimed at overcoming hurdles and satisfying increasing expectations. The first part of this research handled durability issues in these two fields. Novel strategies for attaining high performance organic coatings were explored. In order to validate the proposed strategies, the research has been carried out in collaboration with industrial partners operating in these areas, thus making it possible to produce and test real organic coatings.
The second part of the investigation was aimed at exploring the corrosion protection capabilities of self-repairing organic coatings. The attention was specifically focused onto the preemptive healing polyurethane coatings and their barrier properties.
27
Scrinzi, Erica. "Service life of organic coatings: strategies for improving aesthetic and protective durability". Doctoral thesis, University of Trento, 2011. http://eprints-phd.biblio.unitn.it/650/1/Erica_Scrinzi.pdf.
Testo completoAbstract (sommario):
It is probably needless to mention that organic coatings are of paramount importance nowadays. Although the huge number of applications and their wide spread can suggest that organic coatings have now reached a level of maturity, they are still mysterious from a certain point of view. The behaviour of these systems is not completely understood yet, especially as regarding the relationships between the chemical formulation and the manufacturing/applications technologies on one side, and the final properties on the other side. In this scenario, durability is regarded the most crucial point and finding satisfying design solutions is not straightforward.
Automotive and architecture are perhaps two of the most challenging areas where the durability is claimed at overcoming hurdles and satisfying increasing expectations. The first part of this research handled durability issues in these two fields. Novel strategies for attaining high performance organic coatings were explored. In order to validate the proposed strategies, the research has been carried out in collaboration with industrial partners operating in these areas, thus making it possible to produce and test real organic coatings.
The second part of the investigation was aimed at exploring the corrosion protection capabilities of self-repairing organic coatings. The attention was specifically focused onto the preemptive healing polyurethane coatings and their barrier properties.
28
Nekkanty, Srikant. "Characterization of damage and optimization of thin film coatings on ductile substrates". Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1238182704.
Testo completo
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Yan, Jin. "Aspects of instrumented indentation with applications to thermal barrier coatings". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 177 p, 2007. http://proquest.umi.com/pqdweb?did=1397913961&sid=17&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Quinn, J. P. "Amorphous carbon protective coatings : a comparison between various ultra-thin film characterisation techniques". Thesis, University of Ulster, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.423437.
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Goodenough, John L. "Thermal performance evaluation of artificial protective coatings applied to steam surface condenser tubes". Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85698.
Testo completoAbstract (sommario):
Thesis (MScEng)-- Stellenbosch University, 2013.ENGLISH ABSTRACT: The coating thermal conductivity, the effective coated-tube thermal conductivity and the coating factor of three artificial protective coatings (APCs) applied to condenser tubes are experimentally evaluated. This testing broadens the limited available knowledge of these coatings, which is necessary for effective condenser refurbishment and operation. The coatings are applied to 25.4 mm brass tubes at thicknesses of 44, 46, 50, and 130 μm. Steady state heat transfer tests are performed on these tubes fitted in a double-pipe counter-flow heat exchanger, with heated water in the annulus and coolingwater inside the tube. The experimentally determined thermal conductivities of the coatings range from 0.5 to 2.3 W/m·K. The effective coated-tube conductivity and the coating factor depend on the tube material and size, as well as the coating thickness. A one-dimensional condenser model is used to parametrically investigate the relative overall effect on condenser performance. From these results, coating guidelines for Admiralty brass tubes are proposed in terms of the minimum and maximum coating conductivity and thickness. The effect of the coating on the thermal performance is equivalent to a Heat Exchange Institute (HEI) cleanliness factor of at least 0.85, when adhering to these guidelines. APCs provide a layer of protection against corrosion, erosion and fouling and can preferentially fill tube-wall pits. They can therefore be used to extend the condenser life-span effectively, but, to ensure minimal impact on the overall condenser performance, the coating thickness and conductivity must be carefully controlled and verified experimentally.
AFRIKAANSE OPSOMMING: Die termiese geleidingsvermoë, die effektiewe termiese geleidingsvermoë van bedekte buise en die bedekkingsfaktor van drie kunsmatige beskermingsbedekkingslae wat op kondensorbuise aangewend word, word eksperimenteel geëvalueer. Hierdie evaluering verbreed die beperkte beskikbare kennis oor sodanige bedekkingslae, wat nodig is vir effektiewe kondensor herinrigting en bedryf. Die lae word teen diktes van 44, 46, 50 en 130 μm in 25.4 mm geelkoperbuise aangewend. Warmteoordragstoetse by gestadigde toestande word gedoen op hierdie buise in ’n dubbelpyp-teenvloeiwarmteoordraer, met verhitte water in die annulus en verkoelingswater binne-in die buis. Die eksperimenteel bepaalde termiese geleidingkoëffisiënte wissel tussen 0.5 tot 2.3 W/m·K. Die effektiewe geleidingsvermoë en bedekkingsfaktor hang af van sowel die buis se materiaal en grootte sowel as die dikte van die bedekkings. ’n Eendimensionele kondensormodel word gebruik om die algehele effek van hierdie beskermingsbedekkingslae op kondensorwerkverrigting parametries te ondersoek. Riglyne ten opsigte van aanwending van beskermingslae vir buise van “Admiralty” geelkoper word verskaf in terme van die minimum en maksimum geleidingsvermoë en dikte van bedekkingslae. Met behulp van hierdie riglyne word ’n “Heat Exchange Institue” (HEI) ekwivalente skoonheidsfaktor van minstens 0.85 op ’n nuwe buis behaal. Hierdie kunsmatige bedekkingslaeslae bied beskerming teen korrosie, erosie en bevuiling en kan klein kuile in die buiswand vul. Hulle kan dus gebruik word om die lewensduur van die kondensator te verleng, maar hul dikte en geleidingsvermoë moet noukeurig beheer word en moet eksperimenteel geverifieer word.
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Sharer, Sahir Zalilah. "Investigation of protective mechanisms of organic coatings by thermal testing and electrochemical techniques". Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:8fb242d3-4836-4082-ae95-b7990b593f8a.
Testo completoAbstract (sommario):
This work investigated the protection of mechanism of organic coatings on steel exposed to 3% sodium chloride solution at 50°C, coupled with the use of electrochemical impedance spectroscopy (EIS) to monitor progress of corrosion and degradation of coating. Unlike Walter, EIS measurement was conducted at 50°C as well as after cooling, and measurements at intermediate temperatures have been used to characterize the dependence of the process involved. The proposition that corrosion rate is controlled by the ionic resistance of an organic coating has been tested. EIS results were fitted to a model circuit and changes in the film resistance and charge-transfer resistance with temperature were analyzed to deduce activation energies for the processes involved. Surprisingly, the calculated activation energy for coating resistance is significantly lower than the activation energy for the charge transfer resistance. This suggests that ion conduction in the coating, as apparent in an AC measurement, cannot be controlling the corrosion rate. Potentiostatic pulse tests on coated metal enable iR-corrected polarization curves to be plotted at different temperatures. From this, the activation energy determined from the corrosion currents also higher matches the higher activation energy value calculated from the charge transfer resistance. However, measurements of coating resistance on free films of the same coating also generate higher activation energy values, leaving two possible models that can account for the results.
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Rios, Giancarlo. "Effect of chlorides on the electrochemical behaviour of thermally sprayed aluminium protective coatings". Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/effect-of-chlorides-on-the-electrochemicalbehaviour-of-thermally-sprayed-aluminiumprotective-coatings(2ab6cac3-d935-40d1-948a-02e968199217).html.
Testo completoAbstract (sommario):
Sacrificial metallic coatings have been used in the past, for protecting steel in industrial and urban developments. It has been suggested that thermally sprayed aluminium coatings, immersed in marine environments, are also capable of protecting steel by providing galvanic protection. Researchers have also speculated that the growth of inert oxide products, on top of the coating as well as inside pores and cracks, could enhance even further its protective “shielding” properties. In addition, the self-healing abilities of the coatings, in case of mechanically induce damage, are still a matter of debate. This research project takes a critical look at these assumptions, focusing on the electrochemical response of aluminium metal sprayed (AMS) coatings immersed in 0.6 M NaCl and 0.6 M Na2SO4 solutions, in order to investigate how the presence of chlorides can alter the corrosion behaviour of these coatings. For such, a thin aluminium protective coating was deposited over two different panels (aluminium 1050 and low carbon steel), by the steel making company Fairfield-Mabey, using electric arc thermal spraying (TS). Subsequently, the coated panels were sectioned into smaller specimens, and with the aid of a SEM/EDS, and XRD, observations and analysis were conducted in their surfaces and cross sections, in order to determine the morphology, quality of deposition, and chemical composition of the coatings. Internal porosity/oxide growth after immersion, was studied using 3-D X-ray tomography scanning. Furthermore, the electrochemical behaviour of the coatings (intact and scribed) was also investigated, initially by analyzing the evolution of the open circuit potential in time, when immersed in chloride rich and chloride free environments. Additionally, the anodic polarization behaviour of the substrate and coatings were simultaneously analyzed, by connecting a zero resistance ammeter (ZRA) with the W.E. terminal of a potentiostat. To conclude, EIS and Rp vs. time plots were made in order to corroborate the data obtained from other tests. Results show that although the coating can generate superficial and internal corrosion products, these oxides are not isolating in nature nor will enhance its protective properties. On the other hand, the corrosion potential behaviour of the coatings revealed that AMS coatings have a more active than the substrate; regardless of the environment in which they were immersed or their substrate. Nevertheless, it was also observed that AMS coatings deposited onto steel will corrode faster than their substrates, and for that matter capable of offering corrosion protection, exclusively if chlorides are present in the solution.
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Rajput, Abdul Waqar. "An investigation into the production of UHMWPE fibres and coatings for protective apparel". Thesis, Heriot-Watt University, 2013. http://hdl.handle.net/10399/2879.
Testo completoAbstract (sommario):
The primary aim of this research was to identify a novel process for the manufacturing of UHMWPE fibres and coating. Due to the high molecular weight of UHMWPE, it cannot be converted into fibres by standard extrusion processes it must be firstly dissolved in hydrocarbon solvents such as decalin, kerosene etc, which are unsustainable and potential hazards (to environment and human), then extruded to form a gel fibre. Following the extrusion process the solvent must be removed which involves the use of a secondary solvent e.g. n-hexane, toluene etc. which themselves are potentially hazardous. Research revealed that terpene, a waste product of the orange juice industry was suitable substitute for the currently used solvents. Gel produced as a mixture of UHMWPE and terpene was successfully converted into fibres and fabric coatings. However, the ram process was initially found to be problematic, which was due to the presence of entanglement of the polymer chains. This was resolved by applying acoustic energy to the gel, which optimised the chain alignments thus reducing entanglement and allowing a consistent fibre to be ram extruded. The terpene based extrusion process designed in this research eliminated the solvent removal stage, which eliminated the use of secondary solvent thus eliminating the hazards and cost associated with it. Since the process does not involve a separate solvent removal stage, it has the potential of reducing the processing cost. The terpene also allowed a consistent UHMWPE coating to be applied to the cotton fabric. The coated fabrics showed a good resistance to highly concentrated acids, indicating the potential application of such coatings as protective apparel in the areas involving concentrated acid e.g. liquid acid battery, fertilizer industry, iron and steel making industries where acids are widely used. The coating process developed in this research has expanded the use of UHMWPE beyond the current possibilities.
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Scholvin, Dirk. "Wear resistant nanostructured diamondlike carbon coatings on Ti-alloy". Thesis, Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04082004-180353/unrestricted/scholvin%5fdirk%5f200312%5fms.pdf.
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Sommer, Stacy Ann. "Siloxane-Polyurethane Fouling-Release Coatings Based On PDMS Macromers". Diss., North Dakota State University, 2011. https://hdl.handle.net/10365/29313.
Testo completoAbstract (sommario):
Marine biofouling is the accumulation of organisms onto surfaces immersed
in sea water. Fouling of ships causes an increase in hydrodynamic drag which
leads to performance issues such as increased fuel consumption and a reduced
top operating speed. Fouling-release (FR) coatings are one way that paints have
been used in combating biofouling by allowing for the easy removal of settled
organisms. Traditional FR coatings are silicone elastomers which are soft, easily
damaged, and require a tie coat for adhesion to marine primers. Siloxanepolyurethane
FR coatings have shown promise as FR coatings, providing
enhanced durability and toughness, better adhesion to marine primers, and
comparable FR performance to commercial coatings. Preliminary studies were conducted to explore the use of PDMS macromers
in the preparation of siloxane-polyurethane FR coatings. Attachment and removal
of fouling organisms on the siloxane-polyurethane coatings based on PDMS
macromers was comparable to commercial FR coatings. Extended water aging
was also carried out to determine effects of extended water immersion on the
fouling-release performance of the coatings. At up to four weeks of aging, the FR
performance of the coatings was not affected. Static immersion marine field testing was performed to determine the
fouling-release performance of siloxane-polyurethane coatings prepared with
PDMS macromers. The performance was found to be comparable to commercial FR coatings for up to one year, including water jet removal of slimes, barnacle
push-off removal, and soft sponging. The coatings showed good fouling-release
performance until extremely heavy fouling was allowed to settle.
Underwater hull cleaning was conducted for one siloxane-polyurethane
composition identified as a top performer from static field testing. The coating was
easily cleaned of fouling with rotating brushes for six months. The cleaning
capability of the coating was reduced when large barnacles and other extremely
heavy fouling was present. A commercial FR coating became heavily damaged
with brush cleaning while the siloxane-polyurethane coating remained mostly
undamaged. With more frequent cleaning, it is suspected that siloxanepolyurethane
coatings would show cleaning capability for longer periods of time.
Pigmentation of siloxane-polyurethane coatings based on difunctional
PDMS and PDMS macromers was explored to investigate the effect on FR
performance. Pigmentation with titanium dioxide caused a slight decrease in FR
performance in some cases, but this was easily overcome by the addition of
slightly more PDMS in the coating binder, thus illustrating the feasibility of
siloxane-polyurethane coatings as effective, pigmented FR coatings.
Finally, the exploration of unique PDMS polymer architectures has been
explored for the development of additional, novel, fouling-release coatings. The
incorporation of end-functional PDMS homopolymer molecular brushes and
branched PDMS macromers into siloxane-polyurethane fouling-release coatings
shows promise for the development of unique coatings where improved FR
performance may be obtained.Office of Naval Research (U.S.)
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Soh, Tedric. "Conductive polymer coating for corrosion protection of steel". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112584.
Testo completoAbstract (sommario):
There is an increasing interest in exploring the use of conductive polymers for protecting metals from corrosion. The corrosion resistance of steel coated with the conductive polymer polypheneylenevinylene (PPV) is studied. The corrodant used is deaerated 1% w/w NaCl(aq).The PPV coating is deposited by a homemade spinning coater. The effect of substrate microstructure and surface treatment on PPV coating morphology is investigated. The morphology and surface roughness of the coating are measured by Atomic Force Microscopy (AFM). The PPV coating thickness and substrate surface roughness are measured by profilometer.
Open Circuit Potential (OCP), electrochemical impedance spectroscopy (EIS), linear potentiodynamic voltammetry (Tafel) and optical microscopy were used to characterize the structure and properties of the coatings. The correlation between the coating thickness, the surface treatment of the steel substrate prior to coating, and the corrosion behaviour of PPV coated steel was investigated.
Under the condition of our studies, the level of pH in the solution used for corrosion testing has the strongest effect on the corrosion behaviour of PPV coated steel.
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Ruzic, Vukan. "Mechanisms of protective FeCO₃ film removal in single-phase flow-accelerated CO₂ corrosion of mild steel /". [St. Lucia, Qld.], 2005. http://adt.library.uq.edu.au/public/adt-QU20060626.102924/index.html.
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Gladysz, Gary M. "Remote microwave-enhanced chemical vapor deposition of silicon-nitrogen (SixNy) thin films". Ohio : Ohio University, 1991. http://www.ohiolink.edu/etd/view.cgi?ohiou1183727670.
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Clark, Kelly L. "Synthesis of maleated poly(vinylidene fluoride) in supercritical carbon dioxide medium /". free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p3137685.
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Johnson, Brian Ivins. "Preparation and Detailed X-Ray Photoelectron Spectroscopy and Spectroscopic EllipsometryAnalysis of Ultrathin Protective Coatings". BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/8119.
Testo completoAbstract (sommario):
Ultra-thin films (UTFs) are important in many applications, seen in the semiconductor industry, in chromatography, in sensing, in microfluidics, in aerospace, and in robotics. They also protect materials from corrosion, change surface energies, limit water intrusion into materials, allow material self-cleaning and self-healing, provide scratch resistance, and impart other specific chemical properties. In many cases, UTFs drastically alter surface properties and therefore their applications. It is imperative that proper and consistent characterization be performed on coatings to confirm and understand their desired properties. In Chapter two, Al oxidation under MgF2 protective layers is studied using real time X-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry (SE). These tools allowed me to monitor Al oxidation for both short (hours) and long (months) periods of time. XPS revealed the chemical changes that took place in these materials as a function of time, and these changes were verified with SE. These studies help increase an understanding of aluminum changes under MgF2 protective layers. The third chapter demonstrates ab initio calculations guided X-ray photoelectron spectroscopy (XPS) analysis of surfaces functionalized with fluorinated silanes. This study addresses deficiencies in the literature where CF2:CF3 ratios from experimental XPS data do not match theoretical CF2:CF3 ratios. In a systematic approach, I developed semi-empirical models directed both by ab initio calculations and adjustable, empirical parameters. These models were effective in describing the raw data and exceeded fitting methods used in literature. In Chapter four, SiO2 UTFs with variable thicknesses deposited on Eagle XG® glass substrates are characterized. Challenges associated with this work consisted of similar optical functions of the film and substrate as well as backside reflections from the substrate. These obstacles were met using a multi-sample analysis (MSA), a variable angle spectroscopic ellipsometric approach, and mechanical abrasion/roughening of the substrate backside. With these approaches, I developed a model that precisely fit the data collected from all the samples and gave the correct optical function of the material along with thickness values for each film. Surface characterization represents a commitment of resources. It takes time to make measurements, and it takes time to analyze and understand the results. As presented in this work, I increase understanding of ultra-thin films at interfaces using both a multi-tool approach as well as using multiple analytical methods on data collected from each tool.
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UHLMANN, FRANZISKA JOHANNA LUISE. "Protective Ultra-High Temperature Coatings/ Ceramics (UHTCs) for Ceramic Matrix Composites in Extreme Environments". Doctoral thesis, Politecnico di Torino, 2016. http://hdl.handle.net/11583/2644372.
Testo completoAbstract (sommario):
This thesis is focused on the development of a protective coating system for Cf/SiC SiCARBONTM (Airbus trademark) materials against very high temperatures in extreme environment. Here, we concentrate on the application of this technology in combustion chambers, for example in orbital thrusters. During combustion, the composite material needs to be protected against oxidation caused by the extreme conditions. With the aim to increase the combustion performance using higher temperatures (up to 1850 °C), this thesis deals with the replacement of the current Environmental Barrier Coating (EBC) solution (CVD-SiC coating, Chemical Vapor Deposition) by an Ultra High Temperature Ceramic (UHTC) based coating system. Different challenges of this approach are, for instance, the CTE mismatch between Cf/SiC and UHTC materials and the feasibility to create a dense, thick and adherent UHTC based coating on the hot gas wall (inner wall) of a small combustion chamber.
In this work, a suitable coating process (High Performance Plasma Coating process, HPPC) for inner wall coatings is selected and further developed to create ZrB2 based coatings on Cf/SiC based substrate materials. Based on a parameter study, the coating quality of HPPC based ZrB2 coatings is optimized depending on plasma current, chamber pressure, powder flow rate, preheating and cooling rate. HPPC coatings with different material combinations (ZrB2, ZrB2-SiC, ZrB2-TaC, ZrB2-LaB6) are investigated regarding coating adhesion, voids, composition and thermo-chemical behavior within a combustion chamber-like environment.
To decrease the CTE mismatch between Cf/SiC substrate and a ZrB2 based coating and to increase the thermo-chemical resistance of the composite, the SiC matrix material is modified by ZrB2 and Ta additions. Cf/SiC-ZrB2-TaC composites with different SiC/ZrB2-TaC ratios are fabricated and investigated regarding microstructure, chemical composition and material properties (physical, thermo-physical, mechanical and thermo-chemical). The adhesion of HPPC based ZrB2 coatings on Cf/SiC composites is enhanced by a ZrB2 and TaC matrix modification.
Based on the results, interactions between process parameters, coating composition and substrate material are analyzed and provide the base for ZrB2 based EBCs of the inner wall coatings on Cf/SiC based components. By means of the obtained findings, the potential of several material systems is derived in order to develop a protective coating for long-term applications in combustion chamber environments.
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Arora, M. K. "Diamond like and nitrogen containing carbon films as protective coating on fibre optic pressure sensors". Thesis, University of Reading, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266043.
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Volschenk, Mercia. "Characterisation and development of antifouling coatings for metal surfaces in aquatic environments". Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96989.
Testo completoAbstract (sommario):
Thesis (MSc)--Stellenbosch University, 2015.ENGLISH ABSTRACT: Biofouling in cooling water systems lead to several problems resulting in reduced efficiency and financial losses. Antifouling coatings present an environmental friendly solution to prevent biofouling alternatively to the current use of toxic chemicals in cooling water systems. In this study biofilm growth in a cooling water system was simulated in a modified flow cell system to evaluate industrial antifouling coatings and biocide-enriched coatings as potential antifouling coatings for metal surfaces. The design of a novel antifouling coating was also attempted. Firstly, analytical methods for biofilm monitoring to evaluate selected antifouling coatings and biocides were optimised. Pseudomonas sp. strain CT07 was selected to grow biofilms in the biofilm studies. A metal alloy of stainless steel and mild steel (3CR12) showed no corrosion after a 24 h biofilm growth and was selected as metal surface for the biofilm growth discs. Sonification for 5 min was determined as the optimum biofilm removal method from the growth discs. After biofilm removal the metal growth discs were stained with the LIVE/DEAD® BaclightTM Bacterial Viability kit. Visualisation by confocal laser scanning microscopy and flow cytometry revealed auto fluorescence signals from metal discs that hindered quantitative and qualitative analysis of the metal substrate. The use of Pseudomonas sp. strain CT07::gfp to grow biofilms on the metal growth discs and the exclusion of the stain SYTO9 from the LIVE/DEAD® BaclightTM Bacterial Viability kit reduced auto fluorescence signals from the metal discs. The industrial coatings containing quaternary ammonium salt (QAC), triclosan (TC) and copper oxide (CUO) respectively, showed the highest antimicrobial activity in the disc diffusion test. The minimum inhibition concentrations for silver nitrate (SN) and copper sulphate (CS) were 432 ppm and 160 ppm respectively. A minimum of 6.25 % of furanone solution (FR) was biocidal in the dilution susceptibility test. Secondly, the metal growth discs were coated respectively with the three selected industrial coatings QAC, TC and CUO and the epoxy biocide-enriched coatings SN, CS and FR and chemically characterised before and after exposure to biofilm formation. The antifouling activity of these coatings was also characterized. Growth media inoculated with Pseudomonas sp strain CT07::gfp was circulated through the modified flow cell system via a multichannel peristaltic pump for 48 h before the coated metal discs were removed and washed to perform chemical or antifouling analysis. All the industrial coatings and biocide enriched epoxy coatings complied with the thermal stability requirements of a cooling water system. Scanning electron microscopy (SEM) imaging and Energy dispersive X-ray spectroscopy (EDX) analysis confirmed that the adhesion properties of industrial coatings TC and QAC in aqueous environments were insufficient and that the copper and silver ions leached out of the biocide-enriched epoxy coatings. The qualitative analyses of the attachment of bacteria on the surfaces of both the industrial and biocide enriched epoxy coatings was confirmed by SEM, CLSM. The attached bacteria were removed and analysed quantitatively through plate counts and flow cytometry. None of the industrial coatings or the biocide incorporated epoxy coatings that were used in this study would therefore be efficient for the use on metal surfaces in cooling water systems. Thirdly, several approaches were followed to synthesise a poly(styrene-alt-maleic anhydride) (SMA) coating, chemically bind a furanone derivative, 2,5-dimethyl-4-hydroxy-3-(2H)-furanone, to the polymer back bone of the SMA coating for the application as an antifouling coating for cooling water systems. The synthesis of SMA was confirmed through 1H NMR and SEC and the synthesis of tert-butyl 2-(2-hydroxyethoxy) ethylcarbamate and 4-(2-(2-(tert-butoxycarbonyl)ethoxy)ethoxy)-4- oxobutanoic acid was confirmed through 1H NMR and ES-MS+. The synthesis of the end furanone derivative product could however not be achieved.
AFRIKAANSE OPSOMMING: Bio-aanpaksels in waterverkoelingsisteme veroorsaak talle probleme wat lei tot verminderde doeltreffendheid en finansiële verliese. Antimikrobiese oppervlakbedekkings verskaf ‘n omgewingsvriendelike oplossing om bio-aanpaksels te voorkom en ‘n alternatief vir die huidige gebruik van giftige chemikalieë in waterverkoelingsisteme. Biofilm groei in waterverkoelingsisteme was nageboots in ‘n gewysigde vloeiselsisteem om industriële aanpakwerende en biopsied bevattende antimikrobiese oppervlakbedekkings as potensiële aanpakwerende beskermingslae vir metaaloppervlaktes te evalueer. Die ontwerp van ‘n nuwe aanpakwerende beskermingslaag is ook ondersoek. Eerstens is analitiese moniteringsmetodes vir bio-aanpaksels op geselekteerde aanpakwerende antimikrobiese oppervlakbedekkings en biosiedes geoptimiseer. Pseudomonas sp. stam CT07 was verkies om bio-aanpaksels te simuleer gedurende hierdie studie. ‘n Metaalalooi van vlekvrye staal en sagte staal (3R12) het geen korrosie getoon na 24 uur se groei van bio-aanpaksels nie en is vir hierdie rede gebruik as metaal vir die bio-aanpaksel groeiplate. Dit was vasgestel dat sonifisering die optimale verwyderingsmetode vir groeiplate was. Na verwydering van bio-aanpaksels was die metaal groeiplate bedek met die LIVE/DEAD® BaclightTM bakteriële lewensvatbaarheid-toestel. Visualisering deur middel van konfokale mikroskopie en vloeisitrometrie het outofluoreserende seine vanaf die metaal groeiplate onthul wat kwantitatiewe en kwalitatiewe analise van die metaal substraat verhinder het. Die gebruik van Pseudomonas sp. stam CT07:gfp om bio-aanpaksels te kweek op metal plate en die uitsluiting van SYT09 van die LIVE/DEAD® BaclightTM bakteriële lewensvatbaarheid-toestel, het die outofluoreserende seine van die metaalskywe verminder. Industriële beskerminglae, wat onderskeidelik Kwaternêre ammonium sout (QAC), triclosan (TC) en koperoksied (CUO) bevat, het die hoogste antimikrobiese aktiwiteit in die skyf-diffusie toets getoon. Die minimum inhibisiekonsentrasies vir silwernitraat (SN) en kopersulfaat (CS) was onderskeidelik 432 dpm en 160 dpm. ‘n Minimum konsentrasie van 6.25% van die furanoonoplossing (FO) is geklassifiseer as ‘n biosied in die oplossingstoets.Tweedens was die metaal groei-skywe bedek met drie industriële beskermingslae QAC, TC en CUO en die epoksie-biosied-verrykte lae SN, CS en FR en chemiesgekarakteriseerd voor en na die vorming van bio-aanpaksel. Die karaktereienskappe van die aktiwiteit van die beskermingslae was ook vasgestel. Opgeloste triptiese soja sop vermeng met Pseudomonas sp strain CT07: gfp was gesirkuleer in die gemodifiseerde vloeisel deur ‘n multikanaal peristaltiese pomp vir 48 uur voordat die beskermde metaalskywe verwyder en gewas is om chemiese en aanpakwerende analise uit te voer. Al die industriële beskermingslae en biosied-verrykte epoksie-beskermingslae het aan die vereistes van termiese stabiliteit van ‘n waterverkoelingsisteem voldoen. Skandeer elektronmikroskopie (SEM) en X-straal spektroskopie (EDX) analise het aangetoon dat die aantrekkingseienskappe van industriële beskermingslae TC en QAC in waterige oplossings onvoldoende was en dat die koper- en silwerione uit die biosiedverrykte epoksie-resin beskermingslae diffundeer. Die kwalitatiewe analise van die aanpaksel van bakterieë op die oppervlaktes van beide industriële en biosied -verrykte epoksie-beskermingslae was bevestig deur SEM en CLSM. Die aangepakte bakterieë was verwyder en kwantitatief geanaliseer deur middel van plaattellings en vloeisitrometrie. Nie een van die industriële beskermingslae of die biosied-bevattende epoksie beskermingslae wat in hierdie studie gebruik is, is dus gepas vir gebruik op metaaloppervlaktes in waterverkoelingsisteme nie. Derdens was verskeie pogings aangewend om ‘n poli(stireen-alt-maleic anhidried) (SMA) beskermingslaag chemies te bind tot ‘n furanoon afgeleide 2.5-demitiel-4-hidroksie-3-(2H)- furanoon, tot die polimeer-ruggraat van die SMA beskermingslaag vir aanwending as ‘n aanpakwerende beskermingslaag vir waterverkoelingsisteme. Die sintese van SMA was bevestig deur 1H NMR en SEC en die sintese van tert-butyl 2-(2-hirdoksie-etoksie) etielkarbamaat en 4-(2- (2-(tert-butoksiekarboniel)etoksie)etoksie)-4-oksobutanoiesesuur was bevestig deur 1H NMR en ES-MS+. Die sintese van die uiteindelike afgeleide furanoon kon egter nie behaal word nie.
45
Panin, A. V., A. R. Shugurov, V. P. Sergeev e R. M. Martynyak. "Fracture of Nanostructured Ceramic Coatings on Metal Substrates under Thermal and Mechanical Loadings". Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35309.
Testo completoAbstract (sommario):
Characteristic features of fracture of nanostructured Si-Al-N and Zr-Y-O ceramic coatings on metal substrates subjected to thermal cycling, uniaxial tension and wear tests are studied. The effect of elemental composition of the coatings on their fracture and delamination from the substrate is shown. The effect of bombardment of the Cu substrate by low-energy Zr+ ions on adhesion and fracture of the Si-Al-N heat resistant coatings is investigated. The dependence of the wear resistance of Si-Al-N / Zr-Y-O multilayer coatings on the number of Si-Al-N and Zr-Y-O layers and on their thickness is revealed. It is found that the coating consisting of 6 bilayers is characterized by minimal wear.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35309
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Gannon, Paul Edward. "Study of solid oxide fuel cell interconnects, protective coatings and advanced physical vapor deposition techniques". Diss., Montana State University, 2007. http://etd.lib.montana.edu/etd/2007/gannon/GannonP0507.pdf.
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Le, Page Brian Hamilton. "The assessment and behaviour of crack bridging and crack accommodating protective coatings on reinforced concrete". Thesis, University of Surrey, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244776.
Testo completoAbstract (sommario):
The ingress of carbon dioxide and chloride ions into reinforced concrete can cause corrosion of the steel reinforcement. Cracks and poor quality cover can accelerate this process. Coating the surface of the concrete can increase the life of the structure. A coating must have the ability to bridge cracks that form in the substrate concrete and to accommodate any subsequent movement of that crack without failure. If the coating itself is damaged by substrate cracking then the coating becomes less effective as it no longer provides a barrier to the deleterious agents. There are currently few methods to assess the performance of a coating on a reinforced concrete surface subject to crack formation and subsequent movement. In this thesis a test specimen, machine and methodology are developed to evaluate the crack bridging and crack accommodation performance of these coatings. The specimen is 40mm x 40mm x 160mm mortar prism, coated on one face and axially reinforced with an 8mm steel bar. A crack in the specimen is opened by the application of a tensile load to the ends of the reinforcing bar by a pneumatically powered testing machine. Initial investigations confirmed that the testing machine was reliable and gave reproducible results. A testing program was then carried out to investigate the effects of temperature, coating thickness, artificial weathering and crack width on the crack bridging and crack accommodation behaviour of the coatings. It was found that increasing the thickness of a coating allowed wider cracks to be bridged. Crack accommodating behaviour was found to fall into three regions dependent upon the test temperature. At the lowest temperatures both crack bridging and crack accommodation did not occur. As the temperature was increased crack bridging and crack accommodation occurred but the crack accommodation behaviour was highly variable. As the temperature was increased further a region is encountered where reliable crack bridging and crack accommodation occurred and the variability in crack accommodation behaviour was reduced. Artificial weathering was found to have a detrimental effect on both crack bridging and accommodation performance
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CAMARGO, RITA J. de. "Estudo do tratamento combinado de radiacao ionizante e cobertura de quitosana em mamao papaia (Carica papaya L.)". reponame:Repositório Institucional do IPEN, 2004. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11250.
Testo completoAbstract (sommario):
Made available in DSpace on 2014-10-09T12:49:56Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:03:08Z (GMT). No. of bitstreams: 1 10190.pdf: 8026659 bytes, checksum: a56ea24c48876e3cb2903f4a35974cf3 (MD5)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Dowling, Andrew John, e andrewjohn3055@yahoo com. "Novel strategies for surface micromachining TiN thin films deposited by filtered arc". Swinburne University of Technology. Industrial Research Institute Swinburne, 2005. http://adt.lib.swin.edu.au./public/adt-VSWT20051129.085933.
Testo completoAbstract (sommario):
TiN is used commercially as a wear resistant coating on cutting tools and as a diffusion
barrier in microelectronics. TiN has gained increased interest as a material for MEMS,
however there has been very little work carried out in the area of patterning and releasing TiN for use as a structural MEMS material.
This thesis presents an investigation into the patterning and release of filtered arc deposited TiN thin films using surface micromachining techniques. Two novel strategies are presented for patterning TiN thin films and are achieved using excimer laser micromachining and photolithographic wet-etching.
TiN was deposited onto single crystal Si and Cr and Cu sacrificial layers on Si. The use of Cr as a sacrificial layer was found to facilitate the best quality patterning of the TiN and hence the majority of the work involved using Cr sacrificial layers.
TiN was deposited using partial filtration and full filtration and differences in the ability
to selectively laser pattern the TiN from the Cr sacrificial layer are presented. Various
analytical techniques were employed to investigate the origin of the difference in laser
patterning the TiN thin films.
The establishment of TiN and Cr as a novel material combination for surface micromachined MEMS was extended by etching the Cr sacrificial layer to facilitate the release of TiN stress-measurement structures.
The major finding of this thesis is that filtered arc deposited TiN thin film on Cr can be
used as a material combination to surface micromachine freestanding TiN structures as
high quality patterning and etch selectivity can be achieved using both excimer laser
micromachining and photolithographic wet-etching.
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Dufek, Eric J. "Interfacial investigations of corrosion and corrosion inhibition on the aluminum alloy AA2024-T3". Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1445041831&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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