The effects of coating formulation on thermal characteristics of coating layers were systematically studied for xerographic toner fusion on coated papers. Model coatings were formulated using three types of ground calcium carbonate and one kaolin pigments, each mixed with 6, 10, 18, and 25 pph of styrene butadiene latex binder. Porosity was found to be a key parameter for coating thermal conductivity adjustment, and was determined by the latex concentration. The particle size distribution and morphology of pigments also affect the overall thermal characteristics of coating layers. Print qualities on model coated papers were evaluated by print gloss measurement, toner adhesion test, and pair-wise visual ranking, and it was proved that print gloss is reduced with increasing bulk thermal conductivity of coating layers. The coating layer consisted of Covercarb HP pigment and 10 pph of latex was found to have the best performance in the three print quality evaluation tests.

The effects of coating formulation on thermal characteristics of coating layers were systematically studied for xerographic toner fusion on coated papers. Model coatings were formulated using three types of ground calcium carbonate and one kaolin pigments, each mixed with 6, 10, 18, and 25 pph of styrene butadiene latex binder. Porosity was found to be a key parameter for coating thermal conductivity adjustment, and was determined by the latex concentration. The particle size distribution and morphology of pigments also affect the overall thermal characteristics of coating layers. Print qualities on model coated papers were evaluated by print gloss measurement, toner adhesion test, and pair-wise visual ranking, and it was proved that print gloss is reduced with increasing bulk thermal conductivity of coating layers. The coating layer consisted of Covercarb HP pigment and 10 pph of latex was found to have the best performance in the three print quality evaluation tests.

The objective of this study was to evaluate and compare the print performance of some of the new most promising, cost effective absorbent pigments specialised for inkjet coatings on the market in a continuous drive to find an alternative to silica. The target was a lower production cost for ArjoWiggins inkjet products, OMD 01 and OMD 02. Five absorbent pigments are being evaluated through measuring the qualities of the coating mix itself, visual evaluations of print performance and physical testing of the coated paper. Pigments 1,2 and 3, which all are said to be tailored for inkjet coatings, did not reach the print performance needed for an OMD 01 and OMD 02 equal, due to severe bleed and feathering identified especially on the Epson 950 printer. They are therefore currently not seen as viable formulations. A blend of 50% pigment 5 and 50% silica had excellent print performance as OMD 01 and OMD 02 equivalents and is therefore recommended as a potential alternative to 100% silica. It is of the company’s interest to find a more cost effective solution to their inkjet coatings, and a 50/50 blend of Pigment 5 will save the company more than 35 000 euro per year.

Defect generation and propagation in thin films, such as separation membranes, can lead to premature or catastrophic failure of devices such as polymer electrolyte membrane fuel cells (PEMFC). It is hypothesized that defects (e.g., air bubbles, pin-holes, and holes) originate during the manufacturing stage, if precise control is not maintained over the coating process, and they propagate during system operation. Experimental and numerical studies were performed to detect and eliminate defects that were induced during slot die coating of high-viscosity (1 to 40 Pa-s), shear-thinning solutions. The effects of fluid properties, geometric parameters and processing conditions on air entrainment and coating windows (limited set of processing conditions for which defect-free coating exists) were studied. When smaller slot gaps and coating gaps were used, relatively small bubbles were entrained in the coated film. The air bubble sizes increased as the viscosity of the coating solution decreased. A semi-empirical model correlating the maximum coating speed to a solution's material properties, geometric parameters and processing conditions was developed. Such a predictive model will enable engineers to determine the maximum coating boundary for shear-thinning and Newtonian solutions within certain constraints. Smaller coating gaps and low-viscosity solutions produced higher coating speeds. The surface tension property of the coating solution provided stability to the coating bead. Therefore, solutions with higher surface tension could be processed at higher coating speeds.

Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The aerospace- and automotive industries have an urgency to save space and reduce weight, as well as a need to increase fuel efficiency and reduce emissions. This has led to the use of lightweight structural materials, such as Ti6A14V alloy, which is the most widely used titanium alloy in the aerospace industry. This alloy has an exceptional strength-to-density ratio. The work also covers studies on tool steel 40CrMnMo7 that is used in applications in the tooling-, aerospace and automotive industry. In the quest for improved performance new alternative methods of efficiently machining these materials are investigated. One of the important criteria during machining of these materials is their machinability. This study discusses current research in high performance machining strategies and techniques for advanced materials such as Ti6Al4V and 40CrMnMo7. The properties that make these materials advantageous for the use in the aerospace- and automotive industry also make them difficult to cut. The widespread application of Ti6Al4V in the aerospace industry has encouraged investigations into cooling strategies or -techniques to maintain and improve tool life. Ti6Al4V has a low thermal conductivity causing the heat generated during machining to accumulate on the cutting edge of the tool. During various experiments the application of external compressed air blow cooling (dry cutting), flood cooling, high pressure through spindle cooling (HPTSC) and modifications thereof were investigated. The research project also evaluated the performance of a coating (TiAlN) and various coating treatments. The objectives of the HPTSC modifications were to improve the coolant stream impingement on the tool surface, effectively compressing the thermal barrier, and to reduce the chip-tool contact area. This would lead to a decrease in tool heating and wear. The modified techniques failed to increase tool life but showed signs of increased heat removal capability under the given conditions. It was observed that air blow cooling (dry cutting) delivered the best results when considering cutting materials, coating, coating treatment and cooling strategies or –techniques throughout the experiments conducted. / AFRIKAANSE OPSOMMING: Die Ruimte-en motor-industrie het 'n dringendheid om ruimte te bespaar en gewig te verminder, sowel as 'n behoefte om brandstofdoeltreffendheid te verbeter en emissies te verminder. Dit het gelei tot die gebruik van liggewig strukturele materiale, soos Ti6A14V Allooi , wat die mees gebruikte titanium allooi in die Ruimte is. Hierdie allooi het 'n uitsonderlike krag-tot-digtheid-verhouding. Die studie dek ook gereedskapstaal 40CrMnMo7 wat in die gereedskap, Ruimte-en motor-industrie aangewend word. In die soeke na verbeterde prestasie word nuwe alternatiewe metodes om effektief bewerking van hierdie materiaal ondersoek. Een van die belangrikste kriteria tydens bewerking van hierdie materiaal is die bewerkbaar daarvan. Hierdie studie bespreek die huidige navorsing in hoë prestasie bewerking strategieë en tegnieke vir gevorderde materiale, soos Ti6Al4V en 40CrMnMo7. Die eienskappe wat hierdie materiaal voordelig maak vir die gebruik in die lug-en Ruimte-en motor-industrie, maak dit terselfdetyd moeilik om te sny. Die wydverspreide toepassing van Ti6Al4V in die lug-en Ruimte industrie moedig ondersoeke aan na koelstrategieë of -tegnieke om die instrumentlewe te handhaaf en te verbeter. Ti6Al4V het lae termiese geleidingsvermoë wat veroorsaak dat die hitte, wat gegenereer word tydens bewerking, versamel op die voorpunt van die instrument. Tydens verskillende eksperimente was die toepassing van eksterne saamgeperste lugblaas-verkoeling (droë sny), vloed verkoeling, hoë-druk-deur-die-spil-afkoeling (HPTSC) en aanpassings daarvan geondersoek. Die navorsingsprojek het ook die prestasie van 'n bedekkingslaag (TiAlN) en verskeie bedekkingslaagbehandelings geëvalueer. Die doelwit van die HPTSC aanpassing was om die koelmiddelstroom beklemming op die instrument oppervlak te verbeter, en effektiewelik die termiese versperring saam te pers, asook die skerf-teenoorinstrument kontak te verminder. Dit sou lei tot 'n afname in die instrumentverwarming en -slytasie. Die gewysigde tegnieke het daarin misluk om die instrumentlewe te verhoog, maar het tekens getoon van 'n toename in hitte verwydering vermoë onder die gegewe omstandighede. Dit is dus waargeneem dat lugblaasverkoeling (droë sny) die beste resultate gelewer het in die oorweging van sny materiale, bedekkingslaag, bedekkingslaagbehandelings en verkoeling strategieë of -tegnieke wat regdeur die eksperimente uitgevoer was.

Silver is a precious metal that has traditionally been used for jewellery and money. It also possesses desirable properties such as being corrosion resistant and having good electrical conductivity, resulting in its use for industrial applications. Furthermore, it is also recognised for its tribological properties in non-cost prohibitive applications. Silver can be used as a surface coating and can be deposited using an electroplating process. The utilisation of silver as a surface coating is advantageous and sustainable, as the substrate material properties are enhanced while usage of silver is kept to a minimum. On the other hand, electroplating has been used for over a century. It is a process which is able to produce a layer of uniform and dense coating that adheres well to the substrate metal, thus modifying the properties of the substrate. It benefits from being relatively low cost and is scalable. Silver is electroplated onto stainless steel threaded compression fittings to prevent galling. Traditional silver electroplating, which contains the use of cyanide as a complexing agent in the electroplating bath, is still in use within industry, even to this day. Cyanide, in its various forms can be poisonous, toxic and even lethal, which presents a risk during the silver electroplating process. Furthermore, the toxic wastes created during the cyanide silver electroplating process are detrimental to the environment. The aim of this work is to develop a self-lubricating non-cyanide silver PTFE composite coating suitable for use in threaded compression fittings of the ferruled type. The composite can be considered self-lubricating when a concentration of 8% or more by volume of the self-lubricating PTFE substance is incorporated. My original contribution to knowledge is firstly the successful development and characterisation of a self-lubricating non-cynanide Ag-PTFE coating on stainless steel without a strike resulting in improved CoF of 0.06 from the CoF of 0.6 based on an unlubricated surface. Secondly is the application of a non-cyanide Ag-PTFE MMC for threaded compression fittings. Thirdly is the characterisation of the make-up process of threaded compression fittings through the proposed use of the torque-angle slope in assessing coating performance for threaded compression fittings during make-up. Conclusions that can be drawn for the work are that the performance non-cyanide Ag-PTFE coating exceeded the performance of the pure Ag coating made using the same non-cyanide process. Moreover, the performance of the Ag-PTFE coating shows promising results when compared to the performance of the commercial silver cyanide coating. As a viable replacement to the current silver cyanide process, the self-lubricating non-cyanide Ag-PTFE coating, will improve the working conditions and have a positive contribution to the environment. Moreover, a thinner coating with has the potential to reduce raw material usage and electroplating waste disposal costs.

Made available in DSpace on 2016-06-02T19:56:50Z (GMT). No. of bitstreams: 1 5105.pdf: 3429143 bytes, checksum: ab90868a63759d60a704a41048e64e32 (MD5) Previous issue date: 2013-03-21 / Universidade Federal de Sao Carlos / In order to minimize the effects caused by the development of Brazil, such as the suppression of riparian forest, one has searched for tree species that have the characteristics needed for the recovery of degraded areas. Given this, studies focus on higher plants of encapsulated wild fruits, especially the Mabea fistulifera Mart. Considering that M. fistulifera reproduces through embryonic units that need to be treated, this study aimed to evaluate the drying of wild fruits with explosive dehiscence and the coating "in natura" seed with gel mixture via coating pan, as well as evaluating the tolerance of embryos related to the immediate effects of the processes. Thus, the experimental procedure consisted of the collection of capsular fruits and extraction of seeds of fruit by drying so were analyzed drying methods via radiation, natural convection, forced convection and coating pan. It was considered for the drying methods analysis the opening fruit speed and seed vigor. Thus, all processes allowed physiological recovery of embryos, but the extraction method via pan promoted the highest opening speed of the fruits. Once performed the extraction, the seeds were separated from the inert material obtaining pure batches of seeds. There were also characterizations of size, shape and specific mass obtaining the results (0,78±0,05) cm, (0,67±0,04) cm and (0,59±0,04) cm for Dmax, Dmédio and Dmim, respectively, form factor (0,75±0,01), specific mass of (1,20±0,01) g/cm³ and apparent mass of (0,82±0,01) g/cm³. Analyzes were also made for chemical seed yielding (82,93±0,11)% of dry matter (19,03±0,78)% crude protein, (1,18±0,11) g/kg calcium (0,65±0,03) g/kg magnesium (0,58±0,04) g/kg phosphorus (13,45±0,33) g/kg potassium (0,70±0,03) g/kg of sulfur. The process of coating seeds, through reaction between sodium alginate gel and calcium chloride salt at different angles of inclination and rotation speed of the coating pan, was also analyzed. Thus, it was found that to achieve the coating of the particles it was necessary to prepare the particle surface by chemical scarification, in order to increase the surface roughness of the seed, followed by rehydration with saturated calcium chloride. This way, it was found that the angle of 25° and speed of 25 rpm generate the greatest quantity of mass adhered on seeds. In addition, tests were performed to verify the efficiency of the coating process, and with the lowest angle set in experimental design was found higher values of efficiency. In tests of particle growth was evaluated that the process time was approximately 8 seconds. Finally, the analysis and processing of data obtained through statistical techniques and equations from literature were performed. In this way, the results contributed to improvements in drying processes of wild fruits and the coating of seeds of the pioneer species M. fistulífera. / A fim de minimizar os efeitos causados pelo desenvolvimento do Brasil, tal como, a supressão da Mata Ciliar, buscam-se espécies arbóreas que tenham as características necessárias para a recuperação de áreas degradadas. Diante disto, estudam-se plantas superiores de frutos encapsulados silvestres, das quais se destaca a Mabea fistulífera Mart.. Tendo em vista que a M. fistulífera se reproduz através de unidades embrionárias que precisam ser tratadas, este estudo teve como objetivo avaliar a secagem de frutos silvestres com deiscência explosiva para extração das sementes e do recobrimento das sementes com mistura gel via drageadora, bem como a avaliação da tolerância dos embriões em relação aos efeitos imediatos dos processos. Assim, o procedimento experimental consistiu na coleta dos frutos capsulares e extração das sementes através da secagem dos frutos, de modo que foram analisados os métodos de secagem via radiação solar, convecção natural, convecção forçada e via secagem em drageadora. Considerou-se para a análise dos métodos de secagem a velocidade de abertura dos frutos e qualidade fisiológica das sementes. Assim sendo, verificou-se que todos os métodos permitiram a recomposição fisiológica dos embriões, porém a secagem via drageadora ocorreu com menor tempo de processo em relação às demais técnicas. Uma vez realizada a extração das sementes, estas foram separadas dos materiais inertes obtendo-se lotes puros de sementes. Realizaram-se também as caracterizações de tamanho, forma e massa específica obtendo-se os resultados de (0,78±0,05) cm, (0,67±0,04) cm e (0,59±0,04) cm para os Dmáx, Dmédio e Dmim, respectivamente, fator de forma de (0,075±0,01), massa específica real de (1,20±0,01) g/cm³ e massa específica aparente de (0,82±0,01) g/cm³. Foram feitas também análises para caracterização química das sementes obtendo-se (82,93±0,11)% de matéria seca, (19,03±,078)% de proteína bruta, (1,18±0,11) g/kg de cálcio, (0,65±0,03) g/kg de magnésio, (0,58±0,04) g/kg de fósforo, (13,45±0,33) g/kg de potássio e (0,70±0,03) g/kg de enxofre. Analisou-se também o processo de recobrimento das sementes via reação entre o gel alginato de sódio e o sal cloreto de cálcio em diferentes ângulos de inclinação e velocidade de rotação da panela rotatória (drageadeira). Verificouse que para realizar o recobrimento das partículas foi necessário preparar a superfície das partículas através de escarificação química, visando ao aumento na rugosidade da superfície das sementes, e posterior reumidificação com solução saturada de cloreto de cálcio. Desta forma, constatou-se que o ângulo de 25° e a velocidade de 25 rpm possibilitaram maior quantidade de massa aderida sobre as sementes. Além disto, realizaram-se testes a fim de verificar a eficiência do processo de recobrimento, sendo que nos níveis mais baixos do planejamento experimental verificaram-se os maiores valores de eficiência. Nos testes de crescimento das partículas avaliou-se o tempo de processo que foi aproximadamente de 8 segundos. Por fim, foi realizada a análise e o tratamento dos dados obtidos, mediante técnicas estatísticas e equações advindas da literatura. Desta forma, com os resultados obtidos colaborou-se para avanços nos processos de secagem dos frutos silvestres e no recobrimento das sementes da espécie pioneira M. fistulífera.

Made available in DSpace on 2014-08-20T13:44:44Z (GMT). No. of bitstreams: 1 dissertacao_suemar_goncalves_avelar.pdf: 341956 bytes, checksum: 84385fd5f8e00822859f151c0afe5a06 (MD5) Previous issue date: 2009-03-18 / Seed coating is a strong technology for soybean seeds, bringing great advantages to the farmers, allowing the application of polymers in an appropriate and necessary way to cover the seed. The objective of this research was to evaluate the efficiency of seed coating and the quality of soybean seeds treated with fungicide, insecticide, micronutrients and polymers, during six months of storage. Soybean seeds cultivar CD 209 were submitted to the following treatments: control, fungicide Fludioxonil + Metalaxyl - M (Maxim XL® - 100 mL.100 kg-1 seeds), insecticide Thiametoxan (Cruiser 350 FS® - 200 mL.100 kg-1 seeds), micronutrient ComoFix® (165 mL.100 kg-1 seeds - 24,75 mL Mo and 2,475 mL Co) and the mixture fungicide + insecticide + micronutrient. The same treatments were repeated using the liquid polymer Sepiret 9241 B Green (400 mL.100 kg-1 seed) and also powder polymer Sepiret Flo Branco (0,5 kg.100 kg-1 seeds) + colorant Corasem blue (50 mL.100 kg-1 seeds). Coating efficiency and physical and physiological seed quality in laboratory and seedling performance in the field were evaluated. It was concluded that: the use of polymer in seed coating presents seeds with good appearance, coloration, distribution and adherence of the products to the seed surface; uniformity of product distribution during seed treatment varies with the interaction between product and type of polymer used. Coating with liquid polymer is more efficient in soybean seeds. The use of polymers alters the hectolitre volumetric weight not affecting the physiologic quality. The powder polymer presents adverse latent effects after the storage of the seeds. The polymer should not be used separately in the treatment of seeds. / O recobrimento de sementes é uma tecnologia que vêm se firmando cada vez mais, pois traz grandes vantagens ao agricultor, permitindo a aplicação de polímeros de forma adequada e precisa à semente. O objetivo deste trabalho foi avaliar a eficiência do recobrimento e a qualidade de sementes de soja tratadas com fungicida, inseticida, micronutrientes e polímeros líquido e em pó, durante seis meses de armazenamento. Sementes de soja do cultivar CD 209 foram submetidas aos seguintes tratamentos: testemunha, fungicida Fludioxonil + Metalaxyl M (Maxim XL® - 100 mL.100 kg-1 sementes), inseticida Thiametoxan (Cruiser 350 FS® - 200 mL.100 kg-1 sementes), micronutriente ComoFix® (165 mL.100 kg-1 sementes 24,75 mL Mo e 2,475 mL Co) e a mistura fungicida + inseticida + micronutriente. Os mesmos tratamentos foram repetidos utilizando o polímero líquido Sepiret 9241 B Green (400 mL.100 kg-1 semente) e também o polímero em pó Sepiret Flo Branco (0,5 kg.100 kg-1 sementes) + o corante Corasem azul (50 mL.100 kg-1 sementes). Foram avaliadas a eficiência do recobrimento, qualidade física e fisiológica das sementes em laboratório e o desempenho de plântulas em campo. Concluiu-se que: o uso de polímeros no recobrimento apresentou sementes com boa aparência, coloração, distribuição e aderência dos produtos á superfície das mesmas. A uniformidade de distribuição dos produtos no tratamento de sementes varia com a interação entre produto e tipo de polímero utilizado. O polímero líquido é mais eficiente no recobrimento de sementes de soja. O uso de polímeros altera o peso hectolítrico das sementes de soja, não afetando a qualidade fisiológica. O polímero em pó apresenta efeito latente adverso após o armazenamento das sementes. Os polímeros não devem ser utilizados isoladamente no tratamento de sementes.

Les fluides à seuil sont des matériaux utilisés dans de nombreux procédés industriels au cours desquels ils sont mis en écoulement via leur interaction avec des outils solides. Afin de mieux comprendre comment ils s'étalent sur des surfaces, nous avons étudié d'une part leur enduction verticale sur une plaque mince et d'autre part leur étalement horizontal à l'aide d'une lame. Ces deux études se sont appuyées sur des mesures macroscopiques permettant de suivre la force appliquée à l'outil et des mesures microscopiques de PIV pour déterminer les champs de vitesse dans le matériau. Après confirmation de leur validité par comparaison avec nos résultats expérimentaux, des simulations numériques basées sur la programmation conique ont permis de préciser les écoulements en jeu. Pour l'enduction par trempage, nous observons que dans notre gamme d'étude, le dépôt de fluide à seuil sur la plaque est millimétrique et d'épaisseur constante, sauf aux extrémités. Selon le rapport des forces visqueuses et plastiques, l'enduction est régie par un équilibre "seuillo-gravitaire" ou "visco-gravitaire". Nous avons ensuite caractérisé l'écoulement généré dans le bain par le déplacement de la plaque afin d'expliciter l'origine du phénomène d'enduction. Les simulations numériques précisent la forme de cet écoulement. L'étalement horizontal dans un canal à l'aide d'une lame mince conduit au déplacement d'un amas de fluide faiblement cisaillé par rapport à une région de fluide au repos, par l'intermédiaire d'une couche cisaillée. Nous montrons qu'un modèle simple permet de prédire la dynamique de croissance de l'amas et la relie à la force normale à la lame / Yield stress fluids are used in various industrial processes in which solid tools make them flow. To have a better understanding on how they spread on surfaces, we first studied the vertical coating on a thin plate and then the horizontal blade-coating. Both studies are based on macroscopic measures recording the force applied on the plate and on the microscopic determination on the velocity fields in the fluid by PIV. Numerical simulations based on cone programming, which validity had been confirmed in comparison to our experimental results, specified the flows at stake. In dip-coating, we observed than within our framework, the yield stress fluid deposit on the plate is millimetric and of constant thickness, except on the tips. According to the value of the viscous over plastic forces ratio, the coating is led by a "yield-gravity" or a "visco-gravity" balance. Then, we characterized the flow generated in the bath by the plate displacement in order to clarify the origin of the coating phenomenon. The numerical simulations specified the flow characteristics. The horizontal blade-coating in a channel involves the displacement of a weakly sheared cluster of fluid in relation to a part of fluid at rest, through a sheared layer. We showed that the growing dynamic of the cluster is described with a simple model which links it to the normal force to the plate

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