Dissertations / Theses on the topic 'Cool coating'

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.

The present thesis is devoted to synthesis, through the environmentally friendly citrate sol-gel route, of YIn0.9O3 −ZnO near infrared reflective based pigments, having different chromophore elements (Mn, Cu, Fe), with the aim to add in binder and obtaining cool coatings. A “cool” coating for roofing consists of paint (or glaze) containing color pigments, which do not absorb the infrared portion of the solar spectrum. Cool coatings applied over buildings surface provide an effective solution for passive cooling of building indoors and influencing local outdoor microclimate, mitigating urban heat islands effect (UHIE). The primary purpose is to produce pigments according to an environmentally friendly route, using non-toxic raw materials, as well as short times and low temperatures for synthesis, and without residual waste. The resulting pigments must have high reflectance in the near-infrared so that they can be used in the field of cold paints. To realize the corresponding coatings, pigments were dispersed in two different binders (standard PMMA and industrial binder). For the most interesting pigments, in terms of NIR reflectance, other property, was decided to explore, which define these NIR reflective pigments as smart pigments for building application: the photocatalytic ability.

The deformable roll coating is used in the coil coating industry. The aim is to apply a liquid film on a moving substrate. During application a defect appears. This defect is called “ribbing” and is characterized by periodic ribs parallel to the moving direction of the substrate. The wet thickness applied on the strip is adjusted by different gaps between rolls. The applied speeds and loads on the rolls modify the film thickness and film stability. The elastomeric roll cover is used to permit thinner film application and to delay the onset of ribbing. In this work, the flow in a deformable contact is presented for a negative gap mode. The aim of the study is an optimisation of the application in real industrial conditions by a good mastering of the contact parameters at the strip / roll cover interface. Compared to previous published studies, the presented work will take into account the elastomer cover behaviour used in industrial environments. A specific cyclic compression test is developed to analyse the elastomer behaviour as a function of representative solicitation and chemical environment. A modification of the Young Modulus and relaxation time of the elastomer is observed for different environments. A Prony series is identified with this test results and will be used in the numerical modelling. The finite element simulation of the process is proposed through a solid-fluid interaction. The solid part of the model predicts the mechanical pressure and the fluid part gets the associated wet thickness and free surface position. Moreover, an experimental investigation is performed to correlate the numerical result and the industrial process
L’enduction par rouleaux déformables est utilisée pour appliquer une épaisseur de liquide sur une bande en mouvement. Pendant l’application un défaut nommé “cordage” apparaît et se caractérise par des rides de peinture. L’épaisseur humide appliquée sur la bande est réglée par différents passages entre les rouleaux. L’épaisseur finale et la stabilité de l’application sont modifiées par les vitesses de rouleaux et les efforts de serrages. Le revêtement d’élastomère est utilisé pour appliquer des films plus minces et limiter le cordage. Dans cette étude, l’écoulement dans un contact déformable est présenté. Le but de ce travail est l’optimisation de l’application pour des conditions industrielles par la maîtrise des paramètres de contact à l’interface bande / rouleau. L’originalité de cette étude est la prise en compte des revêtements d’élastomère et de l’environnement industriel. Un test spécifique de compression est développé pour analyser le comportement de l’élastomère face aux sollicitations industrielles. Des modifications du module d’Young et du temps de relaxation sont observées en fonction de l’environnement. A partir de ces résultats des séries de Prony sont identifiées et seront utilisées pour modéliser le comportement viscoélastique de l’élastomère dans la simulation. Une modélisation éléments finis du procédé est réalisée via une architecture de simulation solide-fluide. La première simulation permet d’évaluer la pression dans le contact et la seconde permet d’obtenir l’épaisseur humide et la position de la surface libre. De plus, une étude expérimentale sur une tête d’enduction est réalisée pour corréler les résultats numériques et le procédé industriel

In the search for improvements in the environmental credentials of the organic coatings industry, several different aspects are currently being addressed, including the reduction of volatile organic compounds, development of UV curable coatings and the reduction of potentially hazardous components in the coatings formulations. The aim of this work was to develop the water based primers for coil coating applications as a substitution for chromate conversion coatings. The performance and durability of three novel water based systems applied on alkali cleaned HDGS has been investigated; XPS and ToF-SIMS have been employed to analyse the failure interfaces generated by various test methods designed to assess the performance and durability of each of the systems. In depth analysis has been carried out using ULAM for sample preparation, and XPS and ToF-SIMS were employed to analyse the buried metal/ primer interface, in order to investigate the interface chemistry. A method of post processing data, obtained by surface analysis techniques, was invented to gain a clear understanding of the possible chemical interactions occurred at the metal/primer interface. Adsorption studies were also carried out to encode the interfacial chemistry. The method was used to understand the role of adhesion promoter in the primer formulation, particularly the manner in which it interacts with the substrate and the topcoat and the way it improves the performance and durability; also to determine the role of anti-corrosive additives, especially the manner in which it prevents the corrosion and therefore its contribution toward the performance and durability. The distribution of these components across the primer layer was also investigated considering the possible opportunities of such components enhancing the primer interaction at either interfaces. The finding has been used for re-adjustment of some of process parameters in coil coating systems and specifically water based primers.

This thesis deals with the determination of the effect of controlled relative humidity (RH) on the mechanical properties of coil coatings. The coil coatings studied were based on polyester/melamine technology. The study employed mechanical and dynamic mechanical analysis, using modified environmental chambers, to measure the effects of controlled RH on a range of mechanical parameters. Of particular interest was the effect of controlled RH on the minimum forming temperature of the coil coated metallic panels. This is the temperature below which the coating would fracture. A description has been given of the modifications made to both a mechanical tester and a Dynamic Mechanical Analyser (DMA), which allowed controlled RH experiments to be performed under isothermal or thermal scanning conditions. Comparison of this study with published work showed that some experimental data in the literature could be erroneous due to lack of, or inappropriate, RH conditioning prior to testing. The results showed a good correlation for both free film and coated metal samples between the glass transition temperature (Tg) and the brittle-tough transition (Tbt). A reduction of both the Tg and the Tbt of up to 15°C were found as the controlled RH was increased. A controlled RH and environmentally instrumented slow-draw cupping device was constructed to measure the behaviour of coil coatings on aluminium (Al) and hot dip galvanised steel (HDG-steel) substrates. The importance of indentation depth during the cupping test and the difference between the substrates was emphasised. Fracture mechanics was employed to study differences in performance.

This thesis has investigated Near Infrared (NIR) curing, a fast thermal curing technique for polyester coil coatings used in exterior building applications where fast line speeds are required. The aim has been to further understanding of the NIR cure mechanism. UV/Vis/NIR spectroscopy and curing trials with two types of AdPhos NIR ovens were used to assess the influence of NIR absorbing pigment locus on cure. Firstly, carbon black was removed from red and brown coatings and this resulted in a wider cure window, but re-siting this pigment in the primer layer was unable to maintain coating colour due to top coat opacity. Then the addition of 1 wt.% NIR absorbing pigment to the backing coat was shown to increase top coat PMT by ca. 46°C, thus enabling line speed or oven power settings to be reduced. The convection cure of white coatings with carbon black primers was investigated and a 5 wt.% loading was able to reduce top coat cure time by ca. 3s. In-situ scanning Kelvin probe (SKP) studies showed that rates of coating delamination by cathodic disbondment remained unchanged for primer carbon black loadings of up to 3.5 wt.%. Silver coatings are particularly difficult to cure by NIR, so glass and mica coated flake were investigated as alternatives to aluminium flake, but resulted in coatings with hiding powers reduced by more than 75%. Further formulation suggestions for silver coatings were made, and emissivity and pigment morphology were suggested as potential factors in cure. Finally, NIR pigment additions of up to 10 wt.% to transpired solar collector (TSC) coatings were investigated, and were found to have a much smaller influence on TSC steady state surface temperature than reducing wind speed. An outdoor study of TSC temperature profile revealed that this closely mirrored the incident solar irradiation profile.

The degradation of polyurethane (PU) coil coatings were studied with step scan phase modulation photo-acoustic (SS-PM-PA) FTIR, confocal Raman mapping (CRM) and scanning electron microscopy (SEM). PU coatings were oven cured for 30 seconds to reach a peak metal temperature of 232°C. The cured coatings were exposed in a QUV A accelerated ageing test with exposure time intervals of 1200 hours and 4098 hours. Isophorone diisocyanate (IPDI) cross-linker gave lower cross-linking density and degradation rate to the PU coating compared to hexamethylene diisocyanate (HDI). Cyclic trimer (CT) isocyanate cross-linker gave higher durability compared to biuret (BI). A primary amide and urea entity rich top-film was formed at the surface of degraded PU coatings, with characteristic IR bands at 1640 cm-1 and 1560 cm-1. The decomposition of allophanate in exposed HDI-CT cross-linked PU coating was indicated. The degradation of BI core produced additional urea linkage compared to allophanate. ɛ-caprolactam (Capro) blocked isocyanate gave lower cross-linking density and higher degradation rate compared to methyl ethyl ketoxime (MEKO), and 3,5 dimethyl pyrazole (DMP). The addition of melamine and HALS (less than 5%) improved the durability of PU coatings. The melamine linkage was more sensitive to the degradation compared to the urethane linkage. The higher NCO/OH resulted in more rapid degradation product build-up at the surface of the PU coating in the meantime deterred the decomposition of amide II type linkage. A FTIR peak fitting method was developed for generating degradation index plots, based on the knowledge of degradation chemistry of the PU coatings described above. The degradation rate correlation of the PU coatings exposed in the QUV A test and natural exposure sites including Liverpool, UK (LIV), Vereeniging, South Africa (SA) and Kuala Lumpur, Malaysia (KL) are demonstrated by using degradation index plot methods. The harshness of the natural exposure sites gives the order of KL > SA > LIV.

Reflective roof coatings keep the roof cooler by minimizing solar absorption and maximizing thermal emission. Keeping the surface of the roof cooler allows less heat to be conducted into the interior of the building which reduces the cooling load in air-conditioned buildings and improve comfort conditions in non-air conditioned buildings. A number of cool white materials, compatible with most roofing products, are available on the market. To appeal to homeowners, special cool “color” products have been developed to match the dark colors of conventional residential roofs but are highly reflective in the invisible near-infrared (NIR) spectrum. Although many studies highlight the benefits of cool white coatings on roof membranes of low-slope roofs, knowledge of NIR reflective coatings on asphalt shingles of steep slope roofs remains limited. The intent of this exploratory study is to present a process that can be used to evaluate the perceived and actual benefits of NIR coatings field-applied to asphalt shingles on single-family houses. The proposed process can be applied to a large sample of homes and occupants in a future study. A questionnaire was designed to attempt to evaluate occupants’ perceived benefits in regards to their indoor environment and occupant satisfaction following applications of NIR coatings. Along with subjective data collection, a field-experiment was developed to objectively compare the thermal performance of an NIR reflective field-coated asphalt shingle roof system with that of a conventional asphalt shingle roof system. Questionnaire results indicated that occupants did not perceive any significant changes to their indoor environment but were satisfied overall with the application and appearance of the roof coating. Additionally, 50% of occupants stated that their monthly energy costs somewhat decreased after the application. Interestingly, 63% of respondents experienced some form of roof leak following the coating application. Among those who experienced roof leaks, 100% of the roofs were 10 years or older. Field results showed that the coated roof surface was 2 to 5℉ cooler than the uncoated roof surface at midafternoon. Statistical testing for correlation between coated roof surface temperature and external conditions revealed that relative humidity was negatively correlated with coated roof temperature, while solar altitude angle was positively correlated with coated roof temperature. Multiple linear regression analysis was used to develop a model for predicting the surface temperature of the coated asphalt shingle roofs from the ambient temperature, sky conditions, dew point temperature, relative humidity, solar altitude and azimuth angle.

Le remplacement de monomères d'origine pétrosourcée par des analogues biosourcés améliore la durabilité et diminue la dépendance aux ressources fossiles. De plus, de nouvelles caractéristiques et propriétés sont souvent découvertes. Les polyesters aliphatiques biosourcés ont déjà partiellement remplacé les produits traditionnels. Dans le contexte du projet Sorago, une résine entièrement biosourcée pour les revêtements de prélaquage des produits intérieurs a déjà été introduite sur le marché (Estetic® bio Air, Arcelor Mittal). Pour permettre l'utilisation du produit dans des applications extérieures, sa résistance à la lumière UV et à l'humidité sont à améliorer. Cela pose deux problèmes : Une disponibilité limitée de monomères pouvant introduire de la rigidité dans la résine et la relation entre la structure de la résine et sa dégradation. La vanilline a été choisie comme synthon pour la gamme des monomères rigides et biosourcées. La transformation de sa fonction aldehyde par réaction de Perkin et sa réactivité a été examinée. Dans une série des copolymerisations, l'influence des conditions de réaction sur la composition du produit final a été proposée. Une relation structure-propriétés concernant la température de la transition vitreuse et la viscoélasticité des plusieurs monomères biosourcées a été établie, et comparée avec celle des monomères petrosourcées. Une série des prototypes avec des propriétés très variées a été soumise à un test de vieillissement rapide. Leur dégradation a été suivie sur la base de leur rétention de brillance, par FTIR et par des tests de µ-dureté et d'épaisseur des films. La performance des prototypes biosourcés s'est révélée inférieure à celle d'une résine standard pétrosourcée mais aucune évidence qui suggère que cela est du à la présence des monomères biosourcées n'a été détectée. Cela suggère que la création d'une résine biosourcée et suffisamment durable pour l'extérieur sera possible
Moving away from petroleum and towards biobased materials not only leads to greater sustainability and lower dependence on diminishing fossil resources, but can also catalyse the discovery of new properties. Aliphatic polyesters based on renewable resources have already started to replace traditional products. Within the Sorago project, a fully biobased resin for interior coil coatings has recently been proposed on the market (Estetic® Bio Air, Arcelor Mittal). In order to extend the possible use of the biobased product to exterior applications, an improvement of its resistance to humidity and UV radiation is crucial. This presents two challenges: The limited availability of monomers which provide rigidity in the resin structure and the relationship between the resin composition and its weatherability. Vanillin was chosen as a possible extension to the range of rigid, biobased monomers for polyesterification reactions. The transformation of its aldehyde and its reactivity was studied in terms of catalytic activation and through a series of copolymerisations which revealed the influence of the reaction conditions on the composition of the product. A structure-property relationship concerning the coating glass transition temperature and visco-elastic behaviour of the coating was furthermore established for a series of renewable monomers and contrasted with petroleum based equivalents. Series of prototypes with a wide variety of properties were then subjected to accelerated weathering tests. Their degradation was followed directly by gloss retention and different mechanisms were revealed using FTIR, µ-hardness and film thickness measurements. While the performance of the biobased coating was subpar, no evidence linking its degradation to the presence of renewable monomers was found, suggesting that the creation of a sufficiently durable and renewable exterior coating will be possible

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Neste trabalho estudou-se o comportamento eletroquímico e as características microestruturais de chapas de aço eletrozincado e zincado sem e com revestimentos de fosfatos, oriundos de diferentes banhos fosfatizantes, aplicados pelo processo industrial coil-coating utilizado pela TEKNO S.A. Este trabalho também traz contribuições referentes ao estudo da chapa revestida com Galvalumeâ que é um revestimento composto de uma liga constituída de 55% de alumínio, 43% de zinco e 2% de outros constituintes, entre eles o Silício. Com o estudo desse material pode-se comprovar e determinar qual revestimento com e/ou sem fosfatos tem maior resistência à corrosão. A análise metalográfica superficial das chapas e revestimentos foi realizada por Microscopia Óptica, Microscopia Eletrônica de Varredura e EDS. Ensaios normalizados de rugosidade e de dureza Vickers também foram realizados. A resistência à corrosão proporcionada pelos diferentes revestimentos de zinco e fosfatos foi avaliada por ensaios eletroquímicos como potencial vs tempo em circuito aberto e em corrente controlada, polarização potenciodinâmica, voltametria cíclica e espectroscopia de impedância eletroquímica em solução de cloreto de sódio 3,5% e pH ~ 8,1, equivalente à água marinha. Todo este trabalho teve como objetivo principal, comparar quanto à resistência a corrosão, três diferentes banhos fosfatizantes aplicados nas chapas zincadas, com o intuito de propor ajustes no processo vigente da TEKNO que forneceu todo suporte necessário para realização deste estudo.
In this work it was studied the electrochemical behavior and the microstructure characteristics of zinc coated steel plates with and without phosphate coatings originating from different baths applied for the coil-coating industrial process used by TEKNO S.A. This work also brings referring contributions to the study of Galvalumeâ coating, that is a coating composed of 55% of aluminum, 43% of zinc and 2% of other constituent league, among them the silicon. With this material study it was possible to estimate and determinate which coating has larger resistance to the corrosion. The surface metallographic analysis of all the coatings were accomplished by Optical Microscopy, Scanning Electron Microscopy and Energy Dispersive Spectrography techniques. Normalized methods of rugosity and hardness Vickers were also accomplished. The corrosion resistance for the different coatings was evaluated by electrochemical techniques as potential x time in open circuit , potenciodynamic polarization curves, cyclic voltammetric curves, galvanostatic curves and Electrochemical Impedance Spectroscopy in sodium chloride solution of 3,5% to the pH ~ 8,1 equivalent to the sea water. The main objective, in this work, was to compare the corrosion resistance of three different phosphates baths applied in the galvanized steel sheets, in order improve the effective process of TEKNO that supplied every necessary support for accomplishment of this study.

Orientador : Roberto Zenhei Nakazato
Banca: Tomaz Manabu Hashimoto
Banca: Maria Auxiliadora Silva de Oliveira
Resumo: Neste trabalho estudou-se o comportamento eletroquímico e as características microestruturais de chapas de aço eletrozincado e zincado sem e com revestimentos de fosfatos, oriundos de diferentes banhos fosfatizantes, aplicados pelo processo industrial coil-coating utilizado pela TEKNO S.A. Este trabalho também traz contribuições referentes ao estudo da chapa revestida com Galvalumeâ que é um revestimento composto de uma liga constituída de 55% de alumínio, 43% de zinco e 2% de outros constituintes, entre eles o Silício. Com o estudo desse material pode-se comprovar e determinar qual revestimento com e/ou sem fosfatos tem maior resistência à corrosão. A análise metalográfica superficial das chapas e revestimentos foi realizada por Microscopia Óptica, Microscopia Eletrônica de Varredura e EDS. Ensaios normalizados de rugosidade e de dureza Vickers também foram realizados. A resistência à corrosão proporcionada pelos diferentes revestimentos de zinco e fosfatos foi avaliada por ensaios eletroquímicos como potencial vs tempo em circuito aberto e em corrente controlada, polarização potenciodinâmica, voltametria cíclica e espectroscopia de impedância eletroquímica em solução de cloreto de sódio 3,5% e pH ~ 8,1, equivalente à água marinha. Todo este trabalho teve como objetivo principal, comparar quanto à resistência a corrosão, três diferentes banhos fosfatizantes aplicados nas chapas zincadas, com o intuito de propor ajustes no processo vigente da TEKNO que forneceu todo suporte necessário para realização deste estudo.
Abstract: In this work it was studied the electrochemical behavior and the microstructure characteristics of zinc coated steel plates with and without phosphate coatings originating from different baths applied for the coil-coating industrial process used by TEKNO S.A. This work also brings referring contributions to the study of Galvalumeâ coating, that is a coating composed of 55% of aluminum, 43% of zinc and 2% of other constituent league, among them the silicon. With this material study it was possible to estimate and determinate which coating has larger resistance to the corrosion. The surface metallographic analysis of all the coatings were accomplished by Optical Microscopy, Scanning Electron Microscopy and Energy Dispersive Spectrography techniques. Normalized methods of rugosity and hardness Vickers were also accomplished. The corrosion resistance for the different coatings was evaluated by electrochemical techniques as potential x time in open circuit , potenciodynamic polarization curves, cyclic voltammetric curves, galvanostatic curves and Electrochemical Impedance Spectroscopy in sodium chloride solution of 3,5% to the pH ~ 8,1 equivalent to the sea water. The main objective, in this work, was to compare the corrosion resistance of three different phosphates baths applied in the galvanized steel sheets, in order improve the effective process of TEKNO that supplied every necessary support for accomplishment of this study.
Mestre

L’objectif de ce travail de thèse consiste à optimiser des formulations de coil-coating comportant des nanocharges dans le but d’améliorer les propriétés de robustesse de surface des revêtements obtenus, et ce sans dégrader d’autres propriétés telles que brillance ou flexibilité. Nous avons ainsi sélectionné deux grandes familles de nanocharges: les argiles lamellaires et la silice pyrogénée pour leurs performances mécaniques et leur attrait économique. Nous avons mis en évidence l’importance d’un traitement cationique et d’un mode de dispersion sévère pour l’amélioration de la dispersion des argiles lamellaires. Une partie des agrégats est donc rompue, mais sans pour autant entraîner de conséquences sur les propriétés mécaniques : il faut donc utiliser des nanocharges intrinsèquement plus dures ; c’est le cas des silices. Nous avons alors identifié des interactions fortes entre la silice et la mélamine, figeant la dispersion de la silice et conduisant alors à l’obtention d’un gel fort. Un traitement surfacique de la silice adapté permet de réduire ces interactions, ce qui se traduit par une rhéologie quasi-newtonienne due à une bonne dispersion des charges et à des propriétés mécaniques significativement améliorées. Pour résumer, les interactions développées entre les nanocharges et la matrice organique doivent être choisies de façon optimale puisqu’elles gouvernent non seulement le comportement rhéologique des formulations, mais aussi l’état de dispersion des nanocharges dans le film réticulé ainsi que les différentes propriétés, notamment mécaniques, qui en découlent
The objective of this work consists in optimizing formulations of coil-coating comprising nanofillers with the aim of improving the properties of coatings surface robustness without degrading other properties such as brightness or flexibility. We thus selected two families of nanofillers: lamellate clays and fumed silica for their mechanical performances and their economic attraction. We highlighted the importance of cation treatment and dispersion mode for lamellate clays dispersion improvment. However, a part of aggregates is broken, but without involving effects on the mechanical properties: nanofillers intrinsically harder should be used; it is the case of silicas. We then identified strong interactions between silica and melamine, leading to a strong gel. A surface treatment of adapted silica makes possible to reduce these interactions, which results in a quasi-Newtonian rheology due to a good dispersion of the fillers and significantly improved mechanical properties. To summarize, the interactions developed between nanofillers and organic matrix must be selected in an optimal way since they control not only the rheological behaviour of the formulations, but also the state of dispersion of the nanofillers in the cross linked film as well as various properties, in particular mechanical ones

The present work studies the effect of changes in the formulation of coil coatings on their mechanical properties. The paint systems investigated were generally based on polyester binders that were heat-cured with hexa(methoxymethyl)melamine (HMMM). The chemical structure of the polyester, as well as the concentrations of the materials present in the formulations, was systematically changed and the mechanical properties of free-films of the paints were studied at a variety of different temperatures. Changes in the polyester back-bone resulted in significant changes in the glass transition temperature, Tg, of the paints. For example, the substitution of phthalic acid in the polyester, with iso-phthalic acid, resulted in a decrease in Tg from 36 to 8 °C. At the same time, the respective effect on the mechanical properties was modest. On the other hand, changes in cross-link density resulted in dramatic changes in the mechanical properties of the paints. For example, the maximum strain at failure decreased from 180% to 30% when the concentration of the HMMM cross-linker in the paint was increased from about 5 wt% to about 30 wt%. The effects of temperature and loading rate on the mechanical properties of the free-films of the paints were also investigated. Multi-frequency dynamic mechanical analysis (DMA) was used to obtain the correspondence between time and temperature, at low strains, in a quantitative way. This correspondence was extended to large strains, when tensile data under a range of different temperatures and loading rates were considered. Modelling studies were also performed, where a hybrid visco-elastic/hyper-elastic model was used to predict the tensile behaviour of the paints, with good agreement between the predictions and the measured data. Finally, steel panels coated with a selection of the paint systems were tested in bending, using a T-bend test at 0T. An important finding was the increase in the amount of damage in the coating with time after bending, even though the panels were not deformed further. It was generally found that panels coated with paints which showed large values of strain to failure and toughness when tested as free-films, and also with little tendency for elastic recovery, suffered the least amount of damage when tested in bending.

Considerando aspectos relacionados ao conforto térmico nas edificações e redução da demanda de energia para resfriamento, a utilização de revestimentos frios (que refletem boa parcela da radiação solar recebida e emitem calor) no envelope construtivo pode ser uma alternativa viável para alcançar estas condições. No entanto, a sua durabilidade é o caminho crítico. O presente estudo tem o objetivo de determinar a durabilidade de revestimento multifuncional que reúne as propriedades: fria e autolimpante. Para alcançar esta meta foi formulado um revestimento cimentício monocamada, com e sem a adição de pigmento, ambos com elevada refletância solar e emissividade iniciais. Para manter a refletância ao longo do tempo foi realizada a aplicação de TiO2 anatásio aos revestimentos de duas formas, na primeira as partículas foram adicionadas à matriz cimentícia, enquanto na segunda foram aplicadas superficialmente como pós-tratamento. A exposição à radiação UV proporciona a fotoativação do anatásio que possui capacidade de oxidação da matéria orgânica e alteração do ângulo de contato entre a água e a superfície, facilitando o arraste das sujidades quando esta é molhada tornando-a autolimpante. A manutenção das propriedades frias e a permanência das partículas de TiO2 sobre a superfície foram avaliadas após 6 e 12 meses de exposição natural em estações localizadas nas cidades de Ubatuba, Pirassununga e São Paulo. Após o envelhecimento observou-se a influência determinante das características dos sítios de exposição no comportamento dos materiais. Dentre as formas de aplicação do anatásio verificou-se uma melhora sutil no desempenho dos revestimentos com adição de TiO2 à matriz cimentícia em relação à aplicação superficial do pós-tratamento. O processo de lixiviação observado em ambos os revestimentos expôs as partículas encapsuladas na argamassa com adição de TiO2, enquanto no pós-tratamento houve a remoção da camada superficial de anatásio. Por esse motivo o revestimento com adição apresentou interação com a radiação UV e material a ser degradado por mais tempo. Entretanto os resultados sugeriram que o tempo de exposição foi insuficiente para afirmar este comportamento, pois os resultados são próximos entre si.
Considering aspects related to the indoor thermal comfort in buildings and reducing energy demand for cooling, the use of cool coatings (have high reflectance and emittance of solar radiation) can be a reasonable alternative to achieve these conditions. However, its durability is the critical path. This study aims to measure the durability of multifunctional coating that combines cool and self-cleaning properties. To attain this goal a single-layer cement coating was formulated, with and without pigment added, both with high initial reflectance and emissivity. To maintain these properties over time a coating of TiO2 in crystalline form of anatase was applied to the coating in two ways: in the first way, the particles were mixed to the cementitious layer, and in the second, they were applied superficially as a post-treatment layer. The exposure to UV radiation provides the photoactivation of anatase, activating the oxidation of organic matter and altering the contact angle between water and surface, facilitating the drag of dirt when wet making it self-cleaning. The performance of cool properties and the permanence of TiO2 particles on the surface were evaluated at 6 and 12 months of natural exposure in Ubatuba, Pirassununga and São Paulo. After aging the determinant influence of the sites\' exposure characteristics in the materials performances was observed. A small tendency of improved performance with TiO2 added to the cement layer was verified. In addition, it was noted that these coatings presented higher durability in comparison to the post-treatment layer due to the leaching process, which exposes encapsulated particles in the cementitious mix, providing longer interaction with UV radiation and the organic matter to be degraded. On the other hand leaching caused the partial removal of anatase in the post-treated surfaces. Despite better performance of the TiO2 added coating, the exposure time was insufficient to affirm this behavior because the results are too close to each other.

The continuous coating of steel and galvanised steel coils is referred to as coil coating. Coil coating is considered the most efficient coating method with regard to the amount of coated area per unit of time. Coil coatings include primer coating, top coating and backside coating. In general, the primer coating and top coating need to balance effectively among flexibility, adhesion, and film hardness. As such, saturated polyester resins with the capability of being molecularly engineered have found applications in coil coatings as the key binder. Nowadays, a combination of up to five polyester resins with different molecular structures are employed in coil primer coatings and coil top coat coatings to derive hard yet flexible coatings. The aim of this study was to synthesise and characterise a novel and standalone polyester resin system that would provide multiple properties simultaneously, thus, eliminating the need to use mixtures of polyesters in coil coatings. The multiple properties concerned included high flexibility, excellent adhesion and sufficient chemical resistance. For development of the polyester resin system concerned, a variety of polyols and dicarboxylic acids were polymerised to form polymeric polyester binders. Direct esterification polymerisation technique was employed for synthesis of the polyesters. The results obtained at an early stage indicated that in order to develop such a single resin system, achievement of an optimum balance among flexibility, adhesion and glass transition temperature was essential. Differential scanning calorimetry (DSC) showed that the augmentation or reduction of the glass transition temperature of the saturated polyester led to the augmentation or reduction of the film hardness of the resulting coil coating. Thus, a unique blend of neopentyl glycol, 1,4 cyclohexanedimethanol,1,6 hexanediol, adipic acid, isophthalic acid, and terephthalic acid was polymerised. The resulting product performed efficiently as a standalone binder system in a coil primer coating and a coil top coating, providing all of the required properties. Mglecular structures of the saturated polyesters synthesised were confirmed by carbon-13 and proton CH) nuclear magnetic resonance (NMR) and Fourier transformed infrared (FTIR). Alterations made to molecular structure of the polyesters through partial replacement of their diots with new ones were visible in expected frequency ranges of the resulting 13CNMR and 1HNMR spectra. According to size exclusion chromatography (SEC), molecular weight characteristics of the pilot scale and the industrial scale reproductions of the novel, single component coil coating polyester resin system developed were comparable with the initial product synthesised at the lab scale.

Prosthetic joint infection (PJI) poses a significant risk to implanted patients, requiring multiple surgeries with high rates of reinfection. The primary cause of such infections is otherwise innocuous bacterial species present on the skin that have survived sterilization protocols. Antibiotic drugs have significantly reduced efficacy due to the lack of vasculature in the newly implanted site, allowing microbes to form biofilms with even greater resistance. Graphene oxide (GO) is known to have good biocompatibility while providing drugless antimicrobial properties. The focus of this study is on the development and characterization of a robust coating for titanium alloy implants to promote bone regeneration while inhibiting microbial biofilm adhesion to the implant surface. The novelty of this study is the use of proprietary coal-derived graphene oxide (c-GO) in a biomedical application. c-GO has been demonstrated to have a greater number of functional oxygen groups to promote cell adhesion, while also maintaining thinner layers than possible with graphite exfoliation methods. As an alternative to powerful antimicrobial drugs, it was hypothesized that an advanced coating of graphene-oxide would provide a defensive, passively antimicrobial layer to a titanium implant. While GO is typically quite expensive, the newly developed process provides an economical and environmentally friendly method of producing GO from coal (c-GO). The result is a coating that is inexpensive and capable of halving the biofilm formation of MRSA on titanium-alloy surgical screws in addition to providing improved bone cell adhesion and hard tissue compatibility.
Master of Science
Any time a patient receives implantation surgery, there is a chance of microbes entering the body. These are typically naturally occurring skin flora, harmless but opportunistic. On the surface of implants within the body, these bacteria can form colonies called biofilms, leading to severe and potentially deadly infections, called prosthetic joint infection (PJI). PJI often requires multiple surgeries to remedy, but rates of reinfection are relatively high. As with any surgery, patients are given antibiotic drugs, but implants to not receive blood flow as the body normally would, reducing the effectiveness of antibiotics. Once biofilms are formed, the bacteria become even hardier and resistant even to powerful antibiotics. Graphene oxide (GO) is a carbon material known to have good biocompatibility (i.e., non-toxic) while providing antimicrobial properties. The focus of this study is on the development and characterization of a robust coating for titanium alloy implants to promote bone healing while reducing microbial biofilm colonization on the implant's surface. The novelty of this study is the use of proprietary coal-derived graphene oxide (c-GO) in a biomedical application. c-GO has been demonstrated to have a different chemical makeup than graphite-derived GO, which may improve its efficacy as an antimicrobial coating. As an alternative to powerful antimicrobial drugs, it was hypothesized that a coating of graphene-oxide would provide a defensive, passively antimicrobial layer to a titanium implant. While GO is typically quite expensive, the newly developed one-pot process provides an economical and environmentally friendly method of producing GO from coal (c-GO). The result is a coating that is inexpensive and capable of halving the biofilm formation of MRSA on titanium-alloy surgical screws in addition to providing improved bone cell adhesion and hard tissue compatibility.

Organic coatings are frequently applied to metals, often in circumstances where there is a need to protect the substrate from corrosion or to improve the aesthetic quality of a product. Increasingly, coatings are also expected to provide additional functionality, such as anti-bacterial properties. Concurrent with the need to satisfy ever more demanding specifications, coating formulators are being obliged to comply with stringent environmental legislation. A research area which may benefit the development of coating formulations is that of nanocomposite synthesis, in which the composite additives have at least one dimension in the nanometre size range. The current research has sought to modify a waterborne organic coating primer with two types of nano-sized additives: layered clays and titanium dioxide nanoparticles. Dispersion of the particles at loadings up to 5% w/w was achieved by ball milling and the modified coatings were subjected to numerous tests to ascertain the effect of the additives. Titanium dioxide was found to improve the tribological properties and corrosion resistance of the coatings, while the addition of magnesium aluminium hydroxycarbonate (hydrotalcite) layered clay had a deleterious effect. Some coatings exhibited a cracked morphology, although no correlation between particle loading and the presence of cracks could be determined. A preliminary investigation into substrate preparation was also conducted. This ensured that the degree of cleanliness of the hot-dip galvanized substrates was both satisfactory and consistent.

Solvent-borne thermally cured coil-coating resins contain large amounts of volatile organic solvents in order to obtain suitable flow for film application. This work describes how the expensive and environmental hazardous volatile organic solvent content of a solvent-borne thermally cured polyester/melamine coil-coating system can be reduced by introduction of fatty acid methyl esters (FAMEs) as reactive diluents and modification of the polyester binder resin. The evaluated reactive diluents, two rape seed methyl esters (RMEs), two linseed oil methyl esters (LMEs), and a tall oil methyl ester (TOME) have been evaluated both in a fully formulated clear-coat system and via model studies. Viscosity measurements of wet paint mixtures showed that formulations with hyperbranched polyester binder hold lower viscosity than conventional polyester binder resins and that FAME works as a diluent. Fully formulated clear-coats were cured under simulated industrial coil-coating cure conditions and in a convection oven at lower temperatures respectively. FAME increases the mobility of the system enhancing the film formation process. Free-standing clear-coat films were analyzed with Raman, carbon-14 dating, extraction, dynamic mechanical analysis, and visual observation. Incorporation of FAME could not be confirmed by Raman analysis. However, carbon-14 dating indicated the presence of FAME that could not be extracted from the films. The mechanical properties of the films were also affected by the addition of FAMEs, oven temperature, choice of co-solvent, and flash-off period. Conventional film characterization tests on substrate supported coatings indicated that binder resin structure and cure conditions affect the final film properties. Model studies were performed to clarify how FAME can chemically react through transesterification with the hydroxyl-groups of the polyester. The transesterification reaction between different FAMEs and primary alcohols with and without tertiary hydrogen was monitored with 1H-NMR and real time IR. Evaporation and side reactions, e.g. alkene reactions, are competing factors to the transesterification reaction. The study showed that fatty acid structure, reaction time, and temperature affect the transesterification conversion, degree of side reactions, and choice of catalyst. A pigmented fully formulated polyester/melamine formulation with a reactive diluent was cured at full scale in an industrial coil-coating production facility. Evaluation of the final film properties showed that the coating fulfills the specification of conventional polyester/melamine coil-coating systems.
QC 20100817

The main aim of this thesis work is to investigate the electrical, optical and thermal impact characteristics of cobalt oxide doped antimony tin oxide (CoO-ATO) in the form of thin films and nanofiber membranes. CoO-ATO is a novel composite material that has the potential to be used as reinforced aircraft coatings, military garment coatings, or more specifically as an anti-reflective (AR) top coating for photovoltaic (PV) cells. This work will be critical in determining the effectiveness of using a CoO-ATO layer in these applications. Electrospun nanofibers and spin coated thin films consisting of a polymeric solution of CoO-ATO will be used. Thin films are created using spin coating techniques, and nanofiber membranes are created using an electrospinning technique. Polystyrene (PS) will be used as a solute, and chloroform as a solvent, to create the solution. It is hypothesized that coatings of this material will have improved optical characteristics as compared to traditional ATO coatings and minimum impact from thermal cycling making it a favorable candidate for PV cells. This work will do an electrical, optical and thermal cycling impact characterization of CoO-ATO thin films and nanofiber membranes for a doping range of x% CoO where x ranged from 0.2

L’utilisation d’un col modulaire lors de la pose d’une prothèse totale de hanche introduit une nouvelle interface, entre la tige et le col, qui est susceptible de s’endommager par fretting lors de la marche. L’alliage Ti–6Al–4V est très largement utilisé pour les tiges et les cols. Cependant, les contacts Ti–6Al–4V / Ti–6Al–4V présentent un frottement élevé et une forte usure adhésive dans les conditions de fretting. Les revêtements DLC (diamond-like carbon) ont été largement utilisés comme revêtements protecteurs pour les pièces métalliques. Ainsi, ils peuvent être introduits dans les contacts entre la tige en Ti–6Al–4V et le col en Ti–6Al–4V. L’objectif de cette thèse est d’étudier les comportements tribologiques du revêtement DLC et de l’alliage Ti–6Al–4V dans les conditions de fretting pour application au contact entre la tige et le col. Les essais de fretting sont menés avec un contact cylindre sur plan sous différentes valeurs d’amplitude de déplacement (± 20 μm, ± 40 μm, et ± 70 μm) et de force normale (entre 200 N et 1 200 N). En outre, les effets de différents revêtements (DLC A et DLC B), différentes rugosités de surface (lisse et rugueuse), différentes positions de revêtement (revêtement sur le plan, sur le cylindre et sur les deux surfaces), différents environnements (dans l’air et dans le sérum de veau) sont analysés. Par ailleurs, l'origine du faible frottement du contact entre Ti–6Al–4V et revêtement DLC est explorée. Les propriétés mécaniques du tribofilm formé sur la surface de Ti–6Al–4V frottée sont également étudiées.Pour les tests de fretting sans revêtement (contact Ti–6Al–4V / Ti–6Al–4V) dans l’air, le coefficient de frottement est élevé, entre 0.8 et 1.2. Le volume d’usure croît avec l’amplitude de déplacement. Pour les tests avec revêtement, le Ti–6Al–4V peut être bien protégé, sous des charges relativement faibles. Le coefficient de frottement (d’environ 0,2) et le volume usé sont faibles. Sous fortes charges, le revêtement est presque totalement éliminé. Le frottement et le volume d'usure sont similaires à ceux des essais sans revêtement. Le revêtement plus dur (DLC A) a de meilleures propriétés tribologiques que le DLC B. Le revêtement sur la surface lisse présente une meilleure performance en fretting que sur la surface rugueuse. Le revêtement sur une surface cylindrique présente une meilleure performance tribologique que sur une surface plane. Le revêtement DLC est plus endommagé lorsqu'il glisse contre un revêtement DLC que contre du Ti–6Al–4V non revêtu. Le revêtement fonctionne mieux en présence de sérum que dans l’air. Un tribofilm est formé sur la surface de Ti–6Al–4V frottée lorsqu'il glisse contre un revêtement DLC sous de faibles charges. Le tribofilm présente une dureté plus élevée, un module de Young plus élevé, un module de compression plus élevé, une limite d'élasticité plus élevé que l’alliage Ti–6Al–4V. Un modèle tribologique est proposé pour la formation du tribofilm et l'explication de l'origine du faible frottement, par une analyse approfondie des surfaces de contact, sur les points de vue mécaniques et chimiques
The use of modular neck adapter when placing a total hip prosthesis introduces a new interface, between the femoral stem and the neck adapter, which is propitious to fretting damage during walking. Ti–6Al–4V alloy has been widely used in neck adapters and femoral stems. However, the Ti–6Al–4V / Ti–6Al–4V contacts present high friction and severe adhesive wear under fretting conditions. Diamond-like carbon (DLC) coatings have been widely used as protective coatings for metallic parts. Thus, they can be introduced into Ti–6Al–4V neck adapter / Ti–6Al–4V femoral stem contacts.The objective of this thesis is to investigate the tribological behaviors of DLC coating and Ti–6Al–4V alloy under fretting conditions for application to neck adapter / femoral stem contact. Fretting tests are conducted with a cylinder / flat contact under different values of displacement amplitude (±20 µm, ±40 µm, and ±70 µm) and normal force (between 200 N and 1 200 N). Furthermore, the effects of different DLC coatings (DLC A and DLC B), different surface roughness (smooth and rough), different coating positions (coating on the flat, on the cylinder, and on both surfaces), different environments (laboratory air and calf serum) are analyzed. Besides, the origin of low friction of Ti–6Al–4V / DLC coating contact is explored. The mechanical properties of tribofilm formed on the rubbed Ti–6Al–4V surface is studied.For fretting tests without coating (Ti–6Al–4V / Ti–6Al–4V contact) under laboratory air condition, the friction coefficient is high, between 0.8 and 1.2. The wear volume increases with the displacement amplitude. For fretting tests with coating, Ti–6Al–4V can be well protected under relatively low load conditions. The friction coefficient is low (around 0.2) and the wear volume is small. Under high load conditions, the coating is almost totally removed. The friction and wear volume are similar to tests without coating. The harder coating (DLC A) has better tribological property than DLC B. The coating on the smooth surface exhibits better fretting performance than on the rough surface. Coating on a cylindrical surface shows better tribological performance than on a flat surface. The DLC coating is damaged more severely when it slides against a DLC coating than against the uncoated Ti–6Al–4V alloy. The coating performs better under the serum condition than under the laboratory air condition. A tribofilm is formed on the rubbed Ti–6Al–4V surface when sliding against a DLC coating under low load conditions. The tribofilm shows higher hardness, higher Young’s modulus, higher compression modulus, higher yield strength than the Ti–6Al–4V alloy. A tribological model is proposed for tribofilm formation and explanation of origin of low friction, by in-depth analysis of contact surfaces, on mechanical and chemical points of view

Polymeric coating research requires advanced spectroscopic techniques to perform more efficient and detailed analysis in order to improve knowledge on the component distribution and the degradation of functional groups in the coating. In this work, the advanced non-destructive Step-scan Photoacoustic (SSPA) FTIR and Confocal Raman Microscopy (CRM) techniques were developed and applied to the component distribution studies and degradation studies of polyester/melamine based coil coating. The results show that both techniques are very suitable to carry out both qualitative and quantitative analyses. The degradation of polyester/melamine coil coating exposed in various environmental conditions were studied in detail using the advanced SSPA-FTIR and CRM techniques; the results clearly show that the coating degradation is highly dependent on the weathering conditions. Acid rain was also found to significantly affect the coating durability. Moreover, different pigments incorporated into the coating formulation were also found to have a major impact on the coating durability. With the help of the powerful CRM component distribution analysis function, melamine enriched zones that were very likely to arise from the melamine self-condensation during the curing process of coil coating were clearly observed in the coatings. This finding confirms the hypothesis developed over 20 years in the coil coating research field. Moreover, the durability of the melamine enriched zones was also investigated in this work.

Clothes drying is a very energy-intensive process and it has a high impact in the domestic electricity consumption. In 2005, the EU-28 total energy consumption of household tumble dryers has been estimated at 21 TWh and an increase up to 30 TWh in 2020 will be expected. Therefore, there is a strong interest to improve the efficiency of these household appliances in order to reduce their energy consumption. In fact, the traditional technology of domestic tumble dryers, based on opened or closed air cycle, uses electrical heaters to warm up the process air before the entrance in the drum. Since many years, vapour compression heat pump system has been identified as a suitable technology for more efficient household tumble dryers. In the case of heat pump tumble dryers, it is of the greatest importance to pursue efficiency improvement, by focusing on the single components or process and in the general unit operation. The research focuses on the process of mass transfer in order to improve the condensation rate, leading to a faster removal of moisture. The fin surface characteristics impact on heat and mass transfer rate, as well as on air pressure losses; in a tumble dryer the selection of the surface which leads to the fastest removal of moisture from the air is crucial. For this purpose, an experimental study was undertaken to evaluate the impact of different coatings on evaporator performance during dehumidification process. Studies in the existing literature that investigate into the impact of fin coatings in dehumidification process are limited. Moreover, data at high air absolute humidity (more than 40 gv/kga) are not available in the open literature. A wind tunnel was then designed and built at the ITC-CNR of Padova for experimental investigations. A characterization of the heat exchanger behaviour in dry conditions was performed. Then, tests in dehumidification conditions were carried out to compare experimental results to a dehumidification model. Good model predictions was found using a log-mean enthalpy method (LMED) for tests with air inlet absolute humidity up to 30 gv/kga; for higher values of this parameter, the relative difference between experimental and model results increased. The model assumption of a unit value of the Lewis Factor was not verified for tests with air inlet absolute humidity higher than 30 gv/kga; a Lewis Factor equal to 0.5 was calculated. An alternative model was then considered, based on a modification of the previous log-mean enthalpy difference method (m-LMED). This model included the Lewis Factor value in the calculation of the overall heat transfer coefficient. For tests with air inlet absolute humidity higher than 30 gv/kga, relative differences below 10% was found between experimental results and m-LMED predictions. The core of the experimental activity investigated into the impact of fin coatings on heat exchanger performance in dehumidification conditions. Experimental test conditions were characterized by values of air inlet absolute humidity higher than 40 gv/kga. Three test sample with different surface characteristics were analyzed: one is the untreated aluminium surface, a second with an hydrophilic coating and a third with an hydrophobic coating. Comparisons were carried out according to the total heat transfer rate, the drain rate and the retained weight. Dehumidification tests were performed in steady state conditions at different air volumetric flow rates. The hydrophobic sample presented the lowest values of heat transfer rate and drain rate for all the investigated flow rates, but it showed the highest values of retained weight. On the other hand, the hydrophilic and the untreated samples showed similar values of heat transfer rate, drain rate and retained weight, highlighting no relevant difference between their behaviour in dehumidification conditions.
Il processo di asciugatura dei vestiti ha un elevato impatto nel consumo elettrico domestico. Di conseguenza, c'è un forte interesse nel miglioramento dell'efficienza energetica delle asciugatrici domestiche al fine di ridurre il loro consumo di energia. La tecnologia tradizionale di questi elettrodomestici utilizza resistenze elettriche per riscaldare l'aria prima dell'ingresso nel cesto. Da alcuni anni, i sistemi a pompa di calore sono stati identificati come la tecnologia più adatta per realizzare asciugatrici domestiche più efficienti. Nel caso di questo tipo di elettrodomestico, il miglioramento dell'efficienza del singolo componente, del singolo processo o del funzionamento generale ha un ruolo fondamentale. In particolare, lo studio si è focalizzato sullo scambio di massa all'evaporatore al fine di incrementare il tasso di condensazione, facilitando la rimozione dell'acqua dall'aria di processo. Le caratteristiche della superficie alettata dell'evaporatore influenzano lo scambio di calore, lo scambio di massa e le perdite di carico dell'aria. In un'asciugatrice, la scelta della superficie che consente di ottenere una più rapida deumidificazione è fondamentale. A questo scopo, un'indagine sperimentale è stato intrapreso al fine di valutare l'impatto di diversi rivestimenti superficiali sull'efficienza dell'evaporatore durante il processo di deumidificazione. Gli studi in letteratura inerenti all'impatto di trattamenti della superficie alettata nei processi di deumidificazione sono limitati. Inoltre, dati sperimentali in condizioni di elevata umidità assoluta non sono disponibili in letteratura. Una galleria aerodinamica è stata progettata e costruita all' ITC-CNR di Padova per le indagini sperimentali. I primi test sono stati effettuati per caratterizzare il comportamento dello scambiatore di calore in assenza di deumidificazione. Successivamente, sono state condotte prove in deumidificazione per confrontare i risultati sperimentali con un modello di deumidificazione. Buone previsioni sono state ottenute utilizzando un modello di differenza media efficace entalpica (LMED) per prove con umidità assoluta di ingresso fino a 30 gv/kga; per valori maggiori, la differenza relativa tra i risultati sperimentali e quelli del modello aumenta. Ciò è dovuto da un'invalidazione di un'ipotesi del modello che pone il fattore di Lewis pari a uno; per tali prove è stato calcolato un fattore di Lewis pari a 0.5. Perciò, è stato considerato un modello alternativo, basato su una modifica del precedente (m-LMED). Questo modello include il valore del fattore di Lewis nel calcolo del coefficiente di scambio termico totale. Per i test con umidità assoluta di ingresso maggiore di 30 gv/kga sono state trovate differenze relative inferiori al 10% tra i risultati sperimentali e quelli del modello m-LMED. La maggior parte dell'attività sperimentale ha interessato lo studio dell'impatto dei trattamenti della superficie alettata sull'efficienza dello scambiatore in deumidificazione. Le prove sperimentali sono state caratterizzate da elevati valori di umidità assoluta di ingresso, maggiori di 40 gv/kga. Tre campioni aventi caratteristiche diverse delle alette sono stati analizzati. Il primo è caratterizzato dalla superficie in alluminio non trattato, il secondo da un rivestimento idrofilico ed un terzo da uno idrofobico. Sono stati effettuati confronti in termini di potenza termica scambiata, di tasso di condensazione e di peso dell'acqua ritenuta. Le prove in deumidificazione sono state condotte in condizioni stazionarie a diverse portate volumetriche dell'aria. Il campione idrofobico ha evidenziato i più bassi valori di potenza termica scambiata e di tasso di condensazione, ma i più elevati valori di peso dell'acqua ritenuta. D'altra parte, il campione non trattato ed il campione idrofilico hanno manifestato valori simili in tutte e tre le categorie di confronto, non evidenziando particolari differenze nel loro funzionamento in deumidificazione.

In der blechverarbeitenden Industrie ist in den letzten Jahrzehnten der zunehmende Einsatz organisch bandbeschichteter Bleche zu verzeichnen. Diese so genannten Coil Coating-Werkstoffe werden derzeit vorwiegend im Baubereich für Fassaden und Innenausstattungen, für Haushaltsgeräte und Unterhaltungselektronik sowie zunehmend in der Automobilindustrie eingesetzt. Neuerdings sind Coil Coating-Werkstoffe verfügbar, die aus vier Schichten bestehen und vor allem den ästhetischen Anforderungen der Automobilindustrie für den Außenhautbereich entsprechen. Sie sind eines von vielen Puzzleteilen zur Komplettierung des Gesamtbildes von zukünftigen modernen Fahrzeugkonzepten wie z.B. Modulbauweisen, weil sie die teure Stückbeschichtung bei der Produktion einsparen und somit durch Wegfall von Fertigungsstufen eine Kostenreduzierung erreicht werden kann. Beim Einsatz von neuen Coil Coating-Werkstoffen mit Schichtdicken bis 100 μm ist auf eine fertigungsgerechte Produktgestaltung zu achten. Die zum Fügen von Feinblechen etablierten thermischen Fügeverfahren sind aufgrund der Entstehung von Oberflächenschädigungen nicht anwendbar. Als ökonomische und technologische Fügealternative bietet sich hier das Durchsetzfügen oder Clinchen insbesondere mit der Unterstützung von Wirkmedien an. Jedoch bestehen erhebliche Kenntnisdefizite zum Clinchen organisch bandbeschichteter Feinbleche mit Gesamtschichtdicken größer als 30 μm. Handlungsbedarf resultiert aus den negativen Auswirkungen des Fügeprozesses auf die Beschichtungen und auf die qualitätsbestimmenden Eigenschaften der gefertigten Verbindung. Diese Arbeit soll einen Beitrag zur Erweiterung des Kenntnisstands für das schädigungsfreie Clinchen von organisch beschichteten Blechen leisten. Ziel ist es, ein Clinchverfahren zu entwickeln, das organisch endbeschichtetes Feinblech bei guter Verbindungsfestigkeit schädigungsfrei fügt. Hierzu sind folgende Punkte erarbeitet worden: -In einem ersten Schritt wurde der Stand der Technik zu Coil Coating-Werkstoffen und die Problemstellung beim Clinchen von vorbeschichteten Blechen. -Im nächsten Schritt sind als Ausgangssituation der Arbeit Referenzwerte zur Lackschädigung beim Clinchen von endlackierten Blechen mit konventionellen Clinchwerkzeugen erarbeitet worden. Es zeigt sich, dass mit konventionellen Clinchverfahren Verbindungen mit akzeptabler Festigkeit und guter ästhetischer Erscheinung nicht herstellbar sind. -Aufbauend auf den gewonnenen Erkenntnissen werden neue Ansätze zum schädigungsfreien Clinchen vorgestellt, die auf wirkmedienunterstützte Umformverfahren basieren. Der Schwerpunkt liegt auf der Reduzierung von lokalen Dehnungen und der Reibung während des Clinchens sowie auf der Verbesserung des Werkstoffflusses durch die Minimierung des Werkzeug-Werkstoffkontaktes. Die vorgestellten Lösungsansätze zu Änderungen an der Werkzeuggeometrie und am Clinchverfahren selbst durch den Einsatz von elastischen und flüssigen Wirkmedien werden begleitend mit der Finite-Elemente-Simulation überprüft. -In weiteren praktischen Untersuchungen an einer neu entwickelten Versuchsanlage sind die numerischen Ergebnisse verifiziert worden. Das Clinchen mit flüssigen Wirkmedien zeigt sich dabei als ein gut geeignetes Verfahren zum Fügen mit akzeptabler und deutlich reduzierter Lackschädigung bei guter Verbindungsfestigkeit. -Die Kenntnis von Dehnungszuständen und deren Vergleich mit den sichtbaren Schädigungen auf den Oberflächen ermöglichen die Erschließung der Vorteile aus der Kombination von hydraulischer Tiefung und dem mechanischen Stauchen. In der vorliegenden Arbeit sind neue Lösungsansätze zum Clinchen von Coil Coating-Werkstoffen mit geringsten Oberflächenschädigungen unter Verwendung von Wirkmedien vorgestellt und erläutert worden. Die durchgeführten Untersuchungen zeigen eine Möglichkeit auf, Coil Coating-Werkstoffe schädigungsarm und prozesssicher zu fügen. Die Lösungsansätze und Erkenntnisse dieser Arbeit sollen die Generierung von neuen Perspektiven für die Anwendung von Coil Coating-Werkstoffen unterstützen. Das Ergebnis lässt erwarten, dass in Zukunft neue Schritte auf dem Weg zum Einsatz von endlackiertem getätigt werden können, weil ein sicheres und robustes Fügeverfahren für die Produktion zur Verfügung gestellt werden kann.

In der blechverarbeitenden Industrie ist in den letzten Jahrzehnten der zunehmende Einsatz organisch bandbeschichteter Bleche zu verzeichnen. Diese so genannten Coil Coating-Werkstoffe werden derzeit vorwiegend im Baubereich für Fassaden und Innenausstattungen, für Haushaltsgeräte und Unterhaltungselektronik sowie zunehmend in der Automobilindustrie eingesetzt. Neuerdings sind Coil Coating-Werkstoffe verfügbar, die aus vier Schichten bestehen und vor allem den ästhetischen Anforderungen der Automobilindustrie für den Außenhautbereich entsprechen. Sie sind eines von vielen Puzzleteilen zur Komplettierung des Gesamtbildes von zukünftigen modernen Fahrzeugkonzepten wie z.B. Modulbauweisen, weil sie die teure Stückbeschichtung bei der Produktion einsparen und somit durch Wegfall von Fertigungsstufen eine Kostenreduzierung erreicht werden kann. Beim Einsatz von neuen Coil Coating-Werkstoffen mit Schichtdicken bis 100 μm ist auf eine fertigungsgerechte Produktgestaltung zu achten. Die zum Fügen von Feinblechen etablierten thermischen Fügeverfahren sind aufgrund der Entstehung von Oberflächenschädigungen nicht anwendbar. Als ökonomische und technologische Fügealternative bietet sich hier das Durchsetzfügen oder Clinchen insbesondere mit der Unterstützung von Wirkmedien an. Jedoch bestehen erhebliche Kenntnisdefizite zum Clinchen organisch bandbeschichteter Feinbleche mit Gesamtschichtdicken größer als 30 μm. Handlungsbedarf resultiert aus den negativen Auswirkungen des Fügeprozesses auf die Beschichtungen und auf die qualitätsbestimmenden Eigenschaften der gefertigten Verbindung. Diese Arbeit soll einen Beitrag zur Erweiterung des Kenntnisstands für das schädigungsfreie Clinchen von organisch beschichteten Blechen leisten. Ziel ist es, ein Clinchverfahren zu entwickeln, das organisch endbeschichtetes Feinblech bei guter Verbindungsfestigkeit schädigungsfrei fügt. Hierzu sind folgende Punkte erarbeitet worden: -In einem ersten Schritt wurde der Stand der Technik zu Coil Coating-Werkstoffen und die Problemstellung beim Clinchen von vorbeschichteten Blechen. -Im nächsten Schritt sind als Ausgangssituation der Arbeit Referenzwerte zur Lackschädigung beim Clinchen von endlackierten Blechen mit konventionellen Clinchwerkzeugen erarbeitet worden. Es zeigt sich, dass mit konventionellen Clinchverfahren Verbindungen mit akzeptabler Festigkeit und guter ästhetischer Erscheinung nicht herstellbar sind. -Aufbauend auf den gewonnenen Erkenntnissen werden neue Ansätze zum schädigungsfreien Clinchen vorgestellt, die auf wirkmedienunterstützte Umformverfahren basieren. Der Schwerpunkt liegt auf der Reduzierung von lokalen Dehnungen und der Reibung während des Clinchens sowie auf der Verbesserung des Werkstoffflusses durch die Minimierung des Werkzeug-Werkstoffkontaktes. Die vorgestellten Lösungsansätze zu Änderungen an der Werkzeuggeometrie und am Clinchverfahren selbst durch den Einsatz von elastischen und flüssigen Wirkmedien werden begleitend mit der Finite-Elemente-Simulation überprüft. -In weiteren praktischen Untersuchungen an einer neu entwickelten Versuchsanlage sind die numerischen Ergebnisse verifiziert worden. Das Clinchen mit flüssigen Wirkmedien zeigt sich dabei als ein gut geeignetes Verfahren zum Fügen mit akzeptabler und deutlich reduzierter Lackschädigung bei guter Verbindungsfestigkeit. -Die Kenntnis von Dehnungszuständen und deren Vergleich mit den sichtbaren Schädigungen auf den Oberflächen ermöglichen die Erschließung der Vorteile aus der Kombination von hydraulischer Tiefung und dem mechanischen Stauchen. In der vorliegenden Arbeit sind neue Lösungsansätze zum Clinchen von Coil Coating-Werkstoffen mit geringsten Oberflächenschädigungen unter Verwendung von Wirkmedien vorgestellt und erläutert worden. Die durchgeführten Untersuchungen zeigen eine Möglichkeit auf, Coil Coating-Werkstoffe schädigungsarm und prozesssicher zu fügen. Die Lösungsansätze und Erkenntnisse dieser Arbeit sollen die Generierung von neuen Perspektiven für die Anwendung von Coil Coating-Werkstoffen unterstützen. Das Ergebnis lässt erwarten, dass in Zukunft neue Schritte auf dem Weg zum Einsatz von endlackiertem getätigt werden können, weil ein sicheres und robustes Fügeverfahren für die Produktion zur Verfügung gestellt werden kann.

På SSAB i Borlänge har man upptäckt att avgaser från färgen förorenar ugnarna vid härdning. Avgaserna består av lösningsmedel och andra flyktiga föreningar som sedan förkolnas och faller ner på lackerade plåtband. För att komma runt det här problemet har SSAB tillsammans med Akzo Nobel Industrial Finishes AB, i Gamleby, tillverkat en färg som inte ska ge ifrån sig något lösningsmedel och på så sätt minska bildandet av föroreningar i ugnarna. Färgen heter NOVA GreenCoat och innehåller rapsmetylester, RME, som är ett reaktivt lösningsmedel och ska binda till bindemedlet i färgen och på så sätt hindras från att avgå vid härdning.

Syftet har varit att undersöka om en viss metod fungerar bra för att samla upp avgaser vid härdning. Avgaserna analyserades med GC-MS och härdningen studerades med FTIR. Arbetet har utförts både i Borlänge och i Gamleby.

Metoden för uppsamling av avgaserna visade sig fungera, dock inte särskilt effektivt. Den skulle därför behöva optimeras.

Härdningen kunde till viss del följas med hjälp av FTIR. Förändring i IR-spektrumet syntes för hydroxyltoppen vid cirka 3500 cm^-1. En skillnad kunde ses för en topp vid 2858 cm^-1 som uppkom i det ohärdade materialet innehållande RME, men den försvann under härdning. Toppen ökade med ökad mängd RME och syntes inte alls för de prover som inte innehöll RME.

Samtliga gjorda analyser indikerade att RME avgick vid härdning. Vid analys med GC-MS kunde de föreningar som avgick från RME identifieras som: metyl-14-metyl pentadekanoat och/eller metyl hexadekanoat, olika former av metyl oktadekanoat samt olika former av metyl eikosanoat. Andra föreningar från klarlacken som avgick var lösningsmedel x och y samt i två av proverna hexametoximetylmelamin, HMMM.

Problems with exhaust gases from paint that contaminates the ovens have been discovered at SSAB in Borlänge.  The exhaust gases contain solvents and other volatiles that vaporize from the paint and later on carbonize and fall down on the next coming sheets. SSAB and Akzo Nobel Industrial Finishes AB have developed a paint that is not supposed to vaporize any solvents and therefore reduce the contaminations of the ovens. The paint is called NOVA GreenCoat and contains rapeseed methyl ester, RME. RME is a reactive solvent that is supposed to react with the binder in the paint and therefore be prevented from leaving during thermal cure.

The purpose was to investigate whether a specific method worked well, for collecting the exhaust gases during thermal cure, or not. The collected exhaust gases were analyzed by using GC-MS and the cure was studied with FTIR. The work was executed both in Borlänge and Gamleby.

The method for collecting the exhaust gases worked, unfortunately it wasn’t particularly effective. It therefore needs to be optimized.

The cure could partially be studied by using FTIR. Changes in the IR-spectrum could be followed by looking at the hydroxyl peak at approximately 3500 cm^-1. A certain difference was observed for a peak at 2858 cm^-1 that appeared in the uncured material containing RME. The peak disappeared during cure. It increased with increased amount of RME and could not be observed at all for the samples that did not contain RME.

All the analyzed samples indicated that RME vaporize during cure. When analyzed with GC-MS the volatiles that vaporize from RME were identified as: hexadecanoic acid methyl ester and/or penta decanoic acid methyl-14-methyl ester, different forms of octadecanoic acid methyl ester and different forms of eicosanoic acid methyl ester. Other volatiles that vaporize from NOVA GreenCoat were solvent x and solvent y and for two of the samples hexa metoxy methyl melamine, HMMM, was also found.

In the present work, novel dewatering aids and a novel centrifuge configuration were developed and applied for the purpose of dewatering fine particles. Three different types dewatering reagents were tested in different filtration and centrifugation units. These chemicals included low-HLB surfactants, naturally occurring lipids, and modified lipids. Most of these reagents are insoluble in water; therefore, they were used in solutions of appropriate solvents, such as light hydrocarbon oils and short-chain alcohols. The role of these reagents was to increase the hydrophobicity of the coal and selected mineral particles (chalcopyrite, sphalerite, galena, talc, clay, phosphate, PCC and silica) for the dewatering. In the presence of these reagents, the water contact angles on the coal samples were increased up to 90o. According to the Laplace equation, an increase in contact angle with the surfactant addition should decrease the capillary pressure in a filter cake, which should in turn increase the rate of dewatering and help reduce the cake moisture. The use of the novel dewatering aids causes a decrease in the surface tension of water and an increase in the porosity of the cake, both of which also contribute to improved dewatering. A series of batch-scale dewatering tests were conducted on a variety of the coal and mineral samples using the novel dewatering aids. The results obtained with a Buchner funnel and air pressure filters showed that cake moistures could be reduced substantially, the extent of which depends on the particle size, cake thickness, drying time, reagent dosage, conditioning time, reagent type, sample aging, water chemistry, etc. It was determined that use of the novel dewatering aids could reduce the cake formation time by a significant degree due to the increased kinetics of dewatering. At the same time, the use of the dewatering aids reduced the cake moistures by allowing the water trapped in smaller capillaries of the filter cake. It was found that final cake moistures could be reduced by 50% of what can be normally achieved without using the reagents. However, the moisture reduction becomes difficult with increasing cake thickness. This problem can be minimized by applying a mechanical vibration to the cake, spraying a short-chain alcohol on the cake and by adding a small amount of an appropriate coagulant, such as alum and CaCl2 to the coal and mineral slurries. The novel dewatering aids were also tested using several different continuous filters, including a drum filter, disc filter and horizontal belt filter (HBF). The results obtained with these continuous filtration devices were consistent with those obtained from the batch filters. Depending on the coal and mineral samples and the type of the reagent, 40 to 60% reductions in moisture were readily achieved. When using vacuum disc filters, the cake thickness increased substantially in the presence of the novel dewatering aids, which could be attributed to the increased kinetics of dewatering. A dual vacuum system was developed in the present work in order to be able to control the cake thickness, which was necessary to achieve lower cake moistures. It was based on using a lower vacuum pressure during the cake formation time, while a full vacuum pressure was used during the drying cycle time. Thus, use of the dual vacuum system allowed the disc filter to be used in conjunction with the novel dewatering aids. Its performance was similar to that of HBF, which is designed to control cake thickness and cake formation time independently. The effectiveness of using the novel dewatering aids were also tested in a full-continuous pilot plant, in which coal samples were cleaned by a flotation column before the flotation product was subjected to the disc filter. The tests were conducted with and without using novel dewatering aids. These results were consistent with those obtained from the laboratory and batch-scale tests. The novel centrifuge developed in the present work was a unit, which combined a gravity force and air pressure. The new centrifuge was based on increasing the pressure drop across the filter cake formed on the surface of the medium (centrifuge wall). This provision made it possible to take advantage of Darcy s law and improve the removal of capillary water, which should help lower the cake moisture. A series of tests were conducted on several fine coal and mineral particles and obtained more than 50% moisture reduction even at very fine particle size (2 mm x 0). Based on the test results obtained in the present work, two proof-of-concept (POC) plants have been designed. The first was for the recovery of cyclone overflows that are currently being discarded in Virginia, and the other was for the recovery of fines from a pond in southern West Virginia. The former was designed based on the results of the plant tests conducted in the present work. Cost vs. benefit analyses were conducted on the two POC plants. The results showed very favorable internal rates of return when using the novel dewatering aids. Surface chemistry studies were conducted on the coal samples based on the results obtained in the present investigation. These consisted mainly of the surface characterization of the coal samples (surface mineral composition, surface area, zeta potential, x-ray photoelectron microscopy (XPS)), acid-base interactions of the solids and liquids, dewatering kinetic tests, contact angle measurements of the coal samples and surface force measurements using AFM. In addition, carbon coating on a silica plate using palsed laser deposition (PLD) and Langmuir-Blodgett (LB) film deposition tests were conducted on the sample to better understand the surfactant adsorption and dewatering processes. The test results showed that the moisture reductions on the fine particles agree well with the surface chemistry results.
Ph. D.

碩士
國立高雄應用科技大學
精密模具與機械產研碩士外國專班
99
Coil coating process is a method in which an organic coating material is applied on rolled metal strip in a continuous process. The output of the coil coating industry is a coated metal strip. This has numerous applications in various industries such as outdoor or indoor material for building or home appliances like roof or furniture... The important part of this process is drying and curing the layers of wet organic paint, this is performed by curing ovens. There are some kinds of different curing methods, so that there are also some kinds of oven types. However, the most popular oven is type of convection oven which has advantages of curing complex surfaces and cheaper cost. In this study, typical convection oven for CCL (Coil Coating Line) is shown to express how to dry and cure wet paint layers. The oven includes an Incinerator which dissipates exhausted solvent out of oven into open air after deodorization with firing and heat recuperation to increase effectiveness of using energy.

碩士
國立成功大學
光電科學與工程學系
107
Hydrogen generated by photoelectrochemical solar water splitting process has a great potential to provide the energy consumption. Gallium nitride (GaN) is the materials appropriate for solar water splitting system because its energy band position straddles the redox potential of water. However, n-type GaN (n-GaN) as photoanode has photo-corrosion event in the long-term experiment. In this research, we discuss the characteristics and photoelectrochemical (PEC) properties of Nickel Oxide (NiOx) and Cobalt Oxide (Co3O4) nanoparticles on n-GaN substrate by spin coating process. The various weight ratio of NiOx (1:5 and 3:2) and Co3O4 (1:1 and 1:5) were utilized in this study. These catalysts were covered on n-GaN to prevent photo-corrosion and decrease the solar water splitting reaction overpotential. Interestingly, NiOx nanoparticles can not only avoid the corrosion phenomenon on n-GaN surface, but also enhance photocurrent density while working electrode applied bias of 1V in two-electrode system. In stability test, the hydrogen evolution rate of NiO 3:2 was more rapid than the pristine n-GaN after 5 hours. This result indicates that NiOx nanoparticles covered on n-GaN can enhance lifetime and hydrogen production in PEC cells.

This study involved an assessment of the Pietermaritzburg Waste Minimisation Club (PWMC) during 2001, and a waste minimisation audit conducted at two coil coating lines. Waste minimisation is the reduction or elimination of waste at source4 • It is often achieved through waste minimisation clubs which comprise a small number of companies, generally in the same geographicaI area, that are interested in reducing waste 1"711 . The success of the PMWC was evaluated in terms of the degree to which members implemented waste minimisation principles. Two questionnaires were used to assess the success of the club. These indicated that although the training material gave the members a good understanding of the basic principles of waste minimisation, the material has not given the members enough practical information to implement a waste minimisation programme in their companies. The main barriers to waste minimisation identified include production pressure, operational constraints, lack of human resources and a lack of management time. The drivers for waste minimisation were financial savings, improved plant utilisation and improved environmental performance. Coil coating is a continuous process where a coiled sheet of aluminium is cleaned, pretreated and coated with paint. The flow rates, compositions and costs of all input and output streams to the cleaning and pretreatment sections were gathered from operators or measured. The data were collected over a three-month period to obtain a representative sample, and then analysed to determine waste minimisation opportunities using mass balances, monitoring and targeting, a scoping audit and a true cost of waste assessment. The scoping audit was found to be the most useful technique because it accurately prioritised the waste minimisation opportunities but required a relatively small amount of data for its application. However, the scoping audit underestimated the savings that could be achieved at the coil coating department and therefore the 'scope to save' percentages, which were developed for United Kingdom industries, need modification to better reflect South African industry. Opportunities for waste minimisation on Coil Coating Line 1 (CCL1) included reducing the water consumption, reducing the acid and chromium raw materials consumption, and finding a cheaper energy source for heating the process and rinse tanks. Potential fmancial savings of R116 000 and environmental savings of 18 200 kL of water or effluent per year were calculated for CCL1. The chromium and acid effluent treatment and solid waste disposal are the main areas for waste minimisation on Coil Coating Line 2 (CCL2). Savings could be achieved in these areas by using roller application ofthe chromium pretreatment rather than spray application, and by preventing a leak of chromium pretreatment into the acid process and rinse tanks. Other savings can also be achieved by operating the chromium process tank as a fed-batch process, and operating the alkali and acid process tanks as continuous processes at the specified chemical concentrations and with recycle of the rinse water (dragout). The total financial savings that can be achieved on CCL2 are R5.3 million, and potential environmental savings are 31 600 kL ofeffluent per year.
Thesis (M.Sc.)- University of Natal, Pietermaritzburg, 2002.

碩士
國立中興大學
材料工程學研究所
93
The electrolytic deposition of Co3O4 /CoO thin film on stainless steel was conducted in Co(NO3)2 aqueous solution to be used as a negative electrode in lithium ion thin film batteries. The cathode polarization curves includes 3 major electrochemical reactors: 1. O2 + 4H+ + 4e- → 2H2O (0 V ~ 0. 06V vs. Ag/AgCl ) 2. O2 + 2H2O+2e- → 4 OH- (0.06 V ~ -0.7 V vs. Ag/AgCl ) 3. 2H2O + 2e- → H2 + 2OH- (-0.7 V ~ -2.5 V vs. Ag/AgCl ) The coated specimen or the coating film carried out at 3rd step was subjected to annealing treatments and further characterized by XRD, TGA/DTA, SEM/EDS, AFM and RAMAN Spectroscopy. The as-coating film was Co(OH)2, condensed into CoO partially oxidized into Co3O4 at 200℃-400℃ with the particle size from 10 nm to 20nm, and obviously crystallized at 600℃-1000℃on the coated specimen. The Co3O4/CoO coated specimen annealed at 400℃ for 5hrs was further characterized by CV analysis and charged-discharged tests in LiPF6 and LiClO4 electrolytes respectively using Li metal as the reference and auxiliary electrode. During the first discharging, two electrochemical reactions occurred ：The 1st , Co3O4+2Li++2e-→ 3Co+Li2O and the 2nd ,CoO+2Li++2e- → Co+ Li2O. However, only the reverse of the 2nd was found for the 1st charging. Also, the reversibility in LiPF6 was worse than that in LiClO4, since LiF was formed. The capacity of Co3O4/CoO coated specimen was still found 500 mAh/g after 50 charged-discharged cycles test in LiClO4 electrolyte

Improving the efficiencies of thermal power plants requires an increase of the operating temperatures and thus of the corrosion resistance of heat exchanger materials. Therefore, the present study aimed at developing protective coatings using the pack cementation process. Two types of heat exchanger steels were investigated: a 17%Cr/13%Ni austenitic steel and three ferritic-martensitic steels with 9 (P91 and P92) and 12 %Cr (HCM12A). The austenitic steel was successfully aluminised at 950 °C. For the ferritic-martensitic steels, the pack cementation temperature was decreased down to 650 °C, in order to maintain their initial microstructure. Two types of aluminides, made of Fe2Al5 and FeAl, were developed. A mechanism of the coating formation at low temperature is proposed. Furthermore, combining the pack cementation with the conventional heat treatment of P91 allowed to take benefit of higher temperatures for the deposition of a two-step Cr+Al coating. The corrosion resistance of coated and uncoated steels is compared in simulated coal firing environment for durations up to 2000 h between 650 and 700 °C. It is shown that the coatings offer a significant corrosion protection and, thus, an increase of the component lifetime. Finally, the performance of coated 9-12 % Cr steels is no longer limited by corrosion but by interdiffusion between the coating and the substrate.