Dissertations / Theses on the topic 'Liquid coating'
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Harrison, Matthew Robert. "Liquid bridges in printing and coating." Thesis, University of Leeds, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434213.
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May, Michael Humphrey. "Conformal coating of mammalian cells at a liquid-liquid interface." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq35243.pdf.
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Hoggan, Erik Nebeker. "Spin Coating and Photolithography Using Liquid and Supercritical Carbon Dioxide." NCSU, 2002. http://www.lib.ncsu.edu/theses/available/etd-09232002-125551/.
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This thesis details work on the utilization of dense phase carbon dioxide (CO2) in semiconductor processing. In particular, work is presented on the formulation of CO2 soluble photoresists and the spin coating of those photoresists using only liquid CO2 as a solvent. As part of this spin coating work, a novel high-pressure CO2 spin coater was designed and constructed, and the theoretical equations governing its performance were derived. Also discussed in this thesis are 248 and 193 nm exposures of these CO2 spun films and subsequent development in supercritical CO2. Resist stripping was also performed in CO2. In short, this thesis details the first steps towards a complete replacement of all aqueous and organic solvents in the conventional photolithographic processes of spin coating, developing, and resist stripping. This change not only confers significant environmental advantages, but opens up many new avenues in resist chemistry and promises improvements in large scale film uniformity, elimination of feature collapse, elimination of extraneous processing steps, and improved control of the lithographic process.
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Burris, Matthew L. "Material evaluation of liquid metal corrosion in Zn-Al hot-dip coating baths." Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1400.
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Thesis (M.S.)--West Virginia University, 2000.Title from document title page. Document formatted into pages; contains xi, 106 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 71-73).
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Xu, Jing. "Kinetics of corrosion and dross build-up in molten Zn-Al systems." Morgantown, W. Va. : [West Virginia University Libraries], 2007. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5294.
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Thesis (Ph. D.)--West Virginia University, 2007.Title from document title page. Document formatted into pages; contains x, 235 p. : ill. (some col.). Includes abstract. Includes bibliographical references.
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Takei, Klara, and Bergman Felicia Lindén. "Clogging Prevention in Submerged Entry Nozzles Focusing on CaTiO3 as a Coating Material." Thesis, KTH, Materialvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-128608.
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Iamvasant, Chanon. "Coating mechanical and acoustical design considerations for resistance to solid and liquid particle impact." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/19261/.
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The erosion of components subjected to water droplet impact has been documented in various applications e.g. aircraft and wet-steam turbine blades. In wet-steam turbine systems, erosion of the of leading edge turbine blades causes significant loss of efficiency. Despite the efforts that have been put into this field over the past 50 years, no one has solved the problem of water droplet erosion. This may be attributed to the different damage phenomena; extremely high contact pressure; stress wave propagation; jetting and excessive heating etc. that occur in high- speed water droplet erosion. The main purpose of this thesis work was to attempt to link existing (but fragmented) knowledge of different aspects of water droplet erosion and the requirements to construct a protective coating to resist it. Discoveries from critical literature reviews were that the impact energy may be viewed as mechanical dissipation of stresses/strains or acoustic attenuation of stress waves. Therefore, architectural designs of protective WDE coating structures must try to satisfy both of these considerations. To provide some validation of both the mechanical (stresses/strains) and acoustical (stress waves) considerations, titanium-based monolithic and multilayer PVD coatings will be investigated and characterization techniques (i.e. nano-indentation, x-ray diffractometer (XRD, Optical Microscopy (OM) Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Stylus profilometry) will be performed. Selected (both monolithic and multilayer) coatings will be subjected to both particulate (ball-on-plate) impact testing and water droplet erosion (WDE) testing. This thesis illustrates the versatility of the triode ion-plating PVD technique and its feasibility to produce thick (Ti, Ti(N) and TiN) monolithic coatings and (TiN/Ti, TiN/Ti(N)) multilayer coatings with reliable controllability in terms of chemical composition and designate d i 2 layer thickness. According to the results of this work, there is a definite distinction between the coating requirements for solid particle impact tests and liquid particle water droplet erosion, due to the differences in the way that the impact energy is delivered (i.e. strain rate, duration of the impact impulse, etc.) However, the results are inconclusive as to whether multilayer or monolithic coatings perform better in water droplet erosion. Finally, the information gathered experimentally was analyzed (with existing proposed models and theories) and interpreted to propose a coating architecture which will be superior in water droplet erosion performance.
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Elgadafi, Mansour M. "Angled curtain coating: An experimental study. An experimental investigation into the effect of die angle on air entrainment velocity in curtain coating under a range of operating conditions." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4464.
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In all coating applications, a liquid film displaces air in contact with a dry solid substrate. At a low substrate speed a thin uniform wetting line is formed on the substrates surface, but at a high speed the wetting line becomes segmented and unsteady as air becomes entrained between the substrate and the liquid. These air bubbles affect the quality of the coated product and any means to postpone this at higher speeds without changing the specifications of the coating liquid is desirable. This research assesses the validity of a theoretically based concept developed by Blake and Rushack [1] and exploited by Cohu and Benkreira [2] for dip coating. The concept suggests that angling the wetting line by an angle ß would increase the speed at which air is entrained by a factor 1/cos ß. In practice, if achieved this is a significant increase that would result in more economical operation. This concept was tested in a fast coating operation that of curtain coating which is already enhanced by what is known as hydrodynamic assistance [2]. Here we are effectively checking an additional assistance to wetting. The work, performed on a purposed built curtain coater and a rotating die, with a range of fluids showed the concept to hold but provided the data are processed in a way that separate the effect of curtain impingement from the slanting of the wetting line.
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Elgadafi, Mansour Masoud. "Angled curtain coating : an experimental study : an experimental investigation into the effect of die angle on air entrainment velocity in curtain coating under a range of operating conditions." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4464.
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In all coating applications, a liquid film displaces air in contact with a dry solid substrate. At a low substrate speed a thin uniform wetting line is formed on the substrates surface, but at a high speed the wetting line becomes segmented and unsteady as air becomes entrained between the substrate and the liquid. These air bubbles affect the quality of the coated product and any means to postpone this at higher speeds without changing the specifications of the coating liquid is desirable. This research assesses the validity of a theoretically based concept developed by Blake and Rushack [1] and exploited by Cohu and Benkreira [2] for dip coating. The concept suggests that angling the wetting line by an angle ß would increase the speed at which air is entrained by a factor 1/cos ß. In practice, if achieved this is a significant increase that would result in more economical operation. This concept was tested in a fast coating operation that of curtain coating which is already enhanced by what is known as hydrodynamic assistance [2]. Here we are effectively checking an additional assistance to wetting. The work, performed on a purposed built curtain coater and a rotating die, with a range of fluids showed the concept to hold but provided the data are processed in a way that separate the effect of curtain impingement from the slanting of the wetting line.
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Tang, Man. "Investigation of liquid sodium alginates as mucoadhesive bandages coating the oesophageal mucosa and protecting it from gastric reflux." Thesis, Aston University, 2004. http://publications.aston.ac.uk/11018/.
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Gastro-oesophageal Reflux Disease (GORD), is generally caused by excess gastric reflux back to the oesophagus where damage to the mucosa results in injury. GORD is a very common disease in western countries, more than a quarter of western people are suffering from this disease and there is a trend that the percentage population in eastern countries who are diagnosed as GORD is increasing. GORD and its complications damage the quality of life and can lead to serious oesophageal diseases including Barrett’s disease and oesophageal carcinoma. Sodium alginate dissolved in water forms a viscous liquid and can coat on oesophageal mucosa for a period of time. In this study the ability of the liquid alginate to adhere to the oesophageal mucosa was investigated and the factors that affect this retention were examined. The potential of this liquid alginate as a drug delivery vehicle to extend the duration of contact with the oesophageal mucosa was confirmed by this study. The capacity of an alginate coating to retard acid and pepsin diffusion, the two main aggressive factors in gastric reflux, was investigated. A significant reduction in acid and pepsin diffusion by alginate gel layer was demonstrated in this project, indicating that alginate has great potential to protect against damage caused by acidic reflux. A novel method was introduced using an independent score system to assess the protection of oesophageal tissue by a coating of liquid alginate using microscopy as a technique. This technique demonstrated that alginate can protect the oesophageal epithelial tissue from the damage caused by gastric acid and pepsin. Many techniques were used in this study. The experimental results suggested that liquid sodium alginate is a very promising candidate in treating local oesophageal diseases through forming a coating on the oesophageal mucosal surface, retarding the diffusion of components of gastric refluxate and thus reducing the contact of these noxious factors with the epithelium and minimising injury.
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Galvagno, Mariano. "Modelling of driven free surface liquid films." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/16574.
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In several types of coating processes a solid substrate is removed at a controlled velocity U from a liquid bath. The shape of the liquid meniscus and the thickness of the coating layer depend on U. These dependencies have to be understood in detail for non-volatile liquids to control the deposition of such a liquid and to lay the basis for the control in more complicated cases (volatile pure liquid, solution with volatile solvent). We study the case of non-volatile liquids employing a precursor film model that describes partial wettability with a Derjaguin (or disjoining) pressure. In particular, we focus on the relation of the deposition of (i) an ultrathin precursor film at small velocities and (ii) a macroscopic film of thickness h ∝ U^(2/3) (corresponding to the classical Landau Levich film). Depending on the plate inclination, four regimes are found for the change from case (i) to (ii). The different regimes and the transitions between them are analysed employing numerical continuation of steady states and saddle-node bifurcations and simulations in time. We discuss the relation of our results to results obtained with a slip model. In connection with evaporative processes, we will study the pinning of a droplet due to a sharp corner. The approach employs an evolution equation for the height profile of an evaporating thin film (small contact angle droplet) on a substrate with a rounded edge, and enables one to predict the dependence of the apparent contact angle on the position of the contact line. The calculations confirm experimental observations, namely that there exists a dynamically produced critical angle for depinning that increases with the evaporation rate. This suggests that one may introduce a simple modification of the Gibbs criterion for pinning that accounts for the non-equilibrium effect of evaporation.
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Rohatgi, Vivek. "Liquid Molding of Textile Reinforcements: Analysis of Flow Induced Voids and Effect of Powder Coating on Preforming and Moldability /." The Ohio State University, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487931512618085.
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Ganvir, Ashish. "Microstructure and Thermal Conductivity of Liquid Feedstock Plasma Sprayed Thermal Barrier Coatings." Licentiate thesis, Högskolan Väst, Avd för tillverkningsprocesser, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-9061.
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Thermal barrier coating (TBC) systems are widely used on gas turbine components to provide thermal insulation and oxidation protection. TBCs, incombination with advanced cooling, can enable the gas turbine to operate at significantly higher temperatures even above the melting temperature of the metallic materials. There is a permanent need mainly of environmental reasons to increase the combustion turbine temperature, hence new TBC solutions are needed.By using a liquid feedstock in thermal spraying, new types of TBCs can be produced. Suspension plasma/flame or solution precursor plasma spraying are examples of techniques that can be utilized for liquid feedstock thermal spraying.This approach of using suspension and solution feedstock, which is an alternative to the conventional solid powder feed stock spraying, is gaining increasing research interest, since it has been shown to be capable of producing coatings with superior coating performance.The objective of this research work was to explore relationships between process parameters, coating microstructure, thermal diffusivity and thermal conductivity in liquid feedstock thermal sprayed TBCs. A further aim was to utilize this knowledge to produce a TBC with lower thermal diffusivity and lower thermal conductivity compared to state-of-the-art in industry today, i.e. solid feed stock plasma spraying. Different spraying techniques, suspension high velocity oxy fuel,solution precursor plasma and suspension plasma spraying (with axial and radialfeeding) were explored and compared with solid feedstock plasma spraying.A variety of microstructures, such as highly porous, vertically cracked and columnar, were obtained. It was shown that there are strong relationships between the microstructures and the thermal properties of the coatings.Specifically axial suspension plasma spraying was shown as a very promising technique to produce various microstructures as well as low thermal diffusivity and low thermal conductivity coatings.
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Pavlov, Aleksey D. "Improvement of Electromagnetic Railgun Barrel Performance and Lifetime by Method of Interfaces and Augmented Projectiles." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/986.
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Several methods of increasing railgun barrel performance and lifetime are investigated. These include two different barrel-projectile interface coatings: a solid graphite coating and a liquid eutectic indium-gallium alloy coating. These coatings are characterized and their usability in a railgun application is evaluated. A new type of projectile, in which the electrical conductivity varies as a function of position in order to condition current flow, is proposed and simulated with FEA software. The graphite coating was found to measurably reduce the forces of friction inside the bore but was so thin that it did not improve contact. The added contact resistance of the graphite was measured and gauged to not be problematic on larger scale railguns. The liquid metal was found to greatly improve contact and not introduce extra resistance but its hazardous nature and tremendous cost detracted from its usability. The simulated resistivity augmented projectiles were able to mitigate harmful current build-up on the back of a projectile using different conductivity gradients. Within the range of conductivity of aluminum alloys no simulated gradient was able to fully level the current density, however, once the range was expanded to include the lower conductivity of titanium, nearly uniform current density was achieved.
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Langley, Kenneth Roy. "Investigations of Partially Immersed Spinning Spheres in a Liquid Bath and Butterfly Flight." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3948.
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This thesis examines two important problems in fluid dynamics: that of a partially immersed sphere spinning in a bath of liquid and the measurement of flow velocities around a free flying butterfly. Although the actual problems are quite different, each problem incorporates many of the same principles and techniques. When a hard-boiled egg spins through a pool of milk on the kitchen counter, the milk rises up the sides of the egg and droplets are ejected. This phenomenon occurs when any partially submerged object whose radius increases upward from the fluid surface (e.g., spheres, inverted cones, rings, etc.), spins in a shallow bath of fluid. The fluid ejects from the surface at the maximum diameter in one of three ejection modes: jets, sheets, or sheet breakup. Additionally, a surprisingly large flow rate is induced by the spinning object. Spheres are used in this study to determine the effects of experimental parameters on the induced flow rate. High-speed imaging is used to experimentally characterize the modes of ejection and measure sheet breakup distance and velocities of liquid within liquid sheets. A theoretical model is derived using an integral momentum boundary layer analysis both beneath the free surface and in the thin film attached to the sphere. Experimental results are presented in comparison with predicted behavior with good agreement. The suitability of using a spinning sphere as a pump is also discussed. Second, the use of PIV to measure flow velocities around living species is becoming more widely adopted. Current efforts are starting to measure 3D, time-resolved velocities around insects in tethered flight. This work investigates the use of Synthetic Aperture PIV (SAPIV) in obtaining 3D, time-resolved volumetric velocity fields around a painted lady butterfly in free flight. Results are presented from several time steps during both the down stroke and upstroke of the butterfly showing the development of the leading edge vortex. The velocity field results have limited spatial resolution; however, the results show that SAPIV has potential in further investigating these flow structures. The reconstructed visual hull of the butterfly is also discussed.
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Rao, Shweta Narayan. "Effect of calcium addition by liquid dipping & electrostatic powder coating on firmness, drained weight & calcium content of diced tomatoes." The Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1391508860.
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Sumonsiri, Nutsuda. "Effect of Powder and Target Properties on Food Powder Coating and Comparison of Solid-liquid Separation (SLS) and Vacuum Concentration of Tomato Juice." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1336625577.
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Zhu, Xiaojing. "Processability of Nickel-Boron Nanolayer Coated Boron Carbide." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/28633.
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This dissertation work focuses on the processability improvement of B4C, especially the compaction and sintering improvement of B4C by applying a Ni-B nanolayer coating on individual B4C particles.
A modified electroless coating procedure was proposed and employed to coat nanometer Ni-B layer onto micron-sized B4C particles. The thickness was able to be tuned and controlled below 100 nm. Key parameters, including the amount of nickel source, the amount of the surface activation agent (PdCl2), the amount of the complexing agent (C2H8N2), and the addition rate of the reducing agent (NaBH4) were studied. When the targeted thickness was 5 nm, a continuous and uniform nanolayer coating was obtained with the optimal condition of individual parameter combined.
Reduction of the as-coated B4C powder in a H2-Ar atmosphere was studied between 400-900ºC to reduce the surface oxidesâ Ni2O3 and B2O3. Reduction at 800ºC in hydrogen atmosphere was found to be the most effective condition to remove oxygen in the coating layer, with Ni2B as the reduction product.
Compaction of the as-received, separated and uncoated, and separated with Ni-B coating B4C powders using uniaxial die compaction and combustion driven compaction (CDC) techniques was studied. CDC technique showed the advantage over the traditional uniaxial die compaction by yielding much higher green density and green strength (73% vs. 53.8% green density for the Ni-B coated B4C). Among compacts obtained from the same technique, Ni-B coated B4C compact yielded the densest packing with crack-free compact surface and the highest strength, demonstrating more bonding between B4C particles provided by Ni-B surface coating.
Sintering of the Ni-B coated B4C in an Ar atmosphere between 1150 - 1600ºC with soaking time of 2 hrs and 10 hrs was studied. Liquid phase was found to form during the sintering process. Density measurement showed that the liquid phase Ni-B formed greatly facilitated B4C densification. Considerable density increase and inter-granular connection was achieved when sintered at 1600ºC for 10 hrs. The density enhancement by Ni-B coating was supported by transmission electron microscopy-energy dispersive spectroscopy (TEM-EDS) examination which showed that there was B4C species diffusion into liquid Ni-B phase. This liquid phase enhanced the diffusion of B4C species and formed strong bonding between B4C grains by dissolving small B4C particles and sharp edge and corners of B4C particles. Strength test demonstrated that the Ni-B coating dramatically improved the strength of B4C compacts by yielding a much higher strength of the Ni-B coated samples than the uncoated samples (13.97 vs. 1.79 MPa for the uinaxial die compacted samples, 27.03 vs. 2.21 MPa for the CDC samples). Electrical conductivity Ni-B coated B4C samples was also shown to be improved with the electrical resistivity being reduced from infinite for pure B4C samples to 1.8à 10-3 Ω⠢m for the Ni-B coated samples.
This research work has shown that with the Ni-B coating, B4C densification can start at a temperature as low as 1600ºC via a liquid phase sintering process.Ph. D.
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Myrillas, Konstantinos. "Experimental and numerical investigation of gas jet and liquid film interaction." Doctoral thesis, Universite Libre de Bruxelles, 2011. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209848.
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The topic of this thesis is the interaction between gas jet flow and a liquid film dragged by a solid substrate. This method, known as jet-wiping, is used in several industrial processes. Hot-dip galvanization of steel strips is an important application, where jet wiping is used to control the thickness of the liquid zinc that is applied on a continuous steel substrate. Unsteady phenomena in the process lead to the creation of waves on the liquid film, which is known as undulation. This unwanted phenomenon deteriorates the quality of the final product.The aim of the current study is to identify the causes of the undulation and propose possible solutions to tackle the problem. This is achieved through studying the hydrodynamic interaction between the gas jet flow and the liquid film. Experiments on a laboratory test facility and numerical simulations with 3 different Computational Fluid Dynamics (CFD) codes are employed for that purpose.
Doctorat en Sciences de l'ingénieur
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Byun, Albert Joonsoo. "Chemical Application of Silicon-Based Resonant Microsensor." Thesis, Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/16296.
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The detection of volatile organic compounds in liquid is of interest for applications in public health, workplace safety and environmental monitoring. Traditionally, water samples were taken and analyzed in the laboratory using classical laboratory instrumentation. Current trends target real-time measurements using e.g. chemical microsensors built with microfabrication technologies. Among these, mass-sensitive chemical sensors, based on cantilever beams or surface acoustic devices, have shown substantial promise in gas-phase applications. In a liquid environment, the resonant microstructures typically suffer from high damping, which negatively affects the sensor resolution. In this work, a novel disk-type resonator developed at Georgia Tech was investigated as chemical microsensor for liquid-phase applications. The micromachined resonator vibrates in a rotational in-plane mode shape, reducing damping in a liquid environment. As part of the present research, a measurement setup with a custom-made flow cell for liquid-phase chemical measurements and a coating system to locally deposit polymer sensitive films onto the resonators were developed. To improve the film adhesion on the resonator surface in liquid, physical and chemical binding techniques were developed and tested on wafer samples. Polymers such as poly(4-vinylpyrrolidone), poly(ethylene-co-propylene) and poly(styrene-co-butadiene) were deposited using the custom-designed coating system onto the disk-type resonators. Liquid-phase measurements using tetrachloroethylene as the chemical analyte were performed. The experimental results are discussed, sources of problems are identified and recommendations for future research are made.
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Lévêque, Julien. "Etude du comportement de mousse céramique comme contacteur Gaz/Liquide à contre courant : application à la distillation et à la distillation réactive." Thesis, Toulouse, INPT, 2010. http://www.theses.fr/2010INPT0081/document.
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Ces travaux de thèse abordent la problématique du développement d'internes destinés à la distillation réactive. La méthodologie à suivre est appliquée dans le cas des mousses céramiques en Carbure de Silicium. Le comportement hydrodynamique a été étudié ainsi que la capacité en transfert de matière validant la possible application des mousses en tant que garnissage destiné à la distillation. L'activation catalytique du support a ensuite été développée afin de dégager la méthode la plus intéressante permettant d'approcher le garnissage de référence, le KATAPAK, en termes d'activité catalytique. Le greffage d'Amberlyst 15 est alors apparu comme la voie la plus intéressante pour la possible application des mousses greffées comme interne catalytique destiné à la distillation réactiveThis work of thesis approaches the problems of the development of packings intended for reactive distillation. Methodology to be followed is so applied in the case of ceramic foam in Silicon Carbide. The hydrodynamic behaviour was studied as well as the mass transfer efficiency demonstrating the possible application of ceramic foam as a packing for distillation. The aspect of the catalytic activation of the support was then developed in order to determine the most efficiency method in terms of catalytic activity making it possible to approach reference packing, the KATAPAK. The coating of Amberlyst 15 then appeared as the most interesting way for the possible application of coating foam as catalytic packing for reactive distillation
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Gosset, Anne M. E. "Study of the interaction between a gas flow and a liquid film entrained by a moving surface." Doctoral thesis, Universite Libre de Bruxelles, 2007. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210731.
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This thesis is dedicated to the study of the interaction between a gas jet and a liquid film on a moving surface. This flow configuration corresponds to the gas-jet wiping technique, which is widely used in the coating industry to reduce and control the thickness of a liquid film dragged by a moving substrate. For that purpose, a turbulent slot jet impinges on the liquid surface, involving a runback flow and consequently a lower coating thickness downstream wiping. The different process parameters (nozzle pressure, nozzle to substrate standoff distance, slot width, substrate speed) allow controlling the final film thickness. This metering technique is very common in coating processes, such as the application of gelatin layers on photographic films.The first part of this thesis deals with the prediction of the mean jet wiping flow, i.e. the film thickness distribution in the wiping region. A lubrication model is developed for that purpose, which is simplified to a zero-dimensional model giving directly the final thickness
In the second part, the prediction of splashing occurrence in jet wiping is addressed. The splashing phenomenon in jet wiping is featured by the ejection of droplets from the runback flow, and it constitutes a physical limit to the process. An experimental investigation is conducted on a water model facility, and based on a phenomenological description, a dimensionless correlation in terms of film Reynolds number and jet Weber number is derived for splashing occurrence. The latter is perfectly well validated with observations on industrial lines.
The last part of this thesis is dedicated to the study of the unsteady phenomena occurring on the free surface of the liquid film downstream wiping. This phenomenon has never been understood nor characterized up to now. In the present research, undulation is investigated both theoretically and experimentally. Two model test facilities with dedicated measurement techniques have been designed and constructed. They allow performing parametric studies of the undulation characteristics (amplitude, wavelength, wave velocity), and analyzing the jet/film interaction.
Doctorat en sciences appliquées
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Pallay, Krista Joy. "Surface Modifications to Mitigate Refractory Degradation in High-Temperature Black Liquor Gasifiers." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10488.
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Ceria (CeO2), chromia (Cr2O3), yttria-stabilized zirconia (Y2O3-ZrO2), and sodium cerium oxide (Na2CeO3) were used as barrier coatings on Ufala, an alumina-based ceramic refractory, to determine if they were effective at increasing the life of the refractory in a high-temperature black liquor gasification environment. The ceria, chromia, and yttria-stabilized zirconia coatings were applied at atmospheric pressure using a coating applicator at the Institute of Paper Science and Technology at the Georgia Institute of Technology. The sodium cerium oxide coatings in addition to the three other coating types were applied under atmospheric pressure at C3 International Technologies in Alpharetta, GA. The coated refractory, as well as a set of uncoated refractory used for baseline analysis, were tested using molten synthetic smelt at 1000C for 36 hours. Uncoated refractory samples were also tested for 12, 72, 120, and 168 hours in order to make a kinetic reaction rate determination. The refractory were analyzed using gravimetric and dimensional analysis, X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy to determine the severity of the physical changes that occurred after exposure to molten smelt. The data gathered from these experiments were not able to conclude that barrier coatings are sufficient to impede corrosion of the Ufala refractory material in molten smelt.
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Vostřel, Josef. "Technologické, ekonomické a ekologické aspekty obrábění za sucha." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228551.
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Using of process liquids improves the procedure and results of machining, on the other hand, increases costs and raises some ecological and hygienic issues. In the work there is gradually analyzed mechanism of chip formation, progress and distribution of heat and thermal fields as well as economic and ecological aspects of dry machining and influence of dry machining on durability of tools. In the experimental part there are evaluated data which were measured during the drilling of cylindrical workpiece with regards to progress of workpiece thermal fields while using various kind of tool coating. In the final part there are stated recommendations for practice.
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Laoubi, Saïd. "Réticulation des revêtements en résine époxyde à basse température (50°C) et résistance aux transferts de liquides." Saint-Etienne, 1993. http://www.theses.fr/1993STET4005.
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Cette thèse comporte deux parties. La première partie concerne la réticulation d'un revêtement en résine époxyde à basse température (50°C). La cinétique de réticulation est étudiée par calorimétrie. Une équation simple basée sur la loi d'Arrhenius est déterminée et permet de prévoir la cinétique de réticulation du revêtement. Une corrélation peut être établie entre la dureté du revêtement et la valeur de l'état d'avancement de la réticulation. La deuxième partie concerne les phénomènes de transfert de matières qui ont lieu lorsque le revêtement est en contact avec des liquides. Deux liquides sont utilisés pour simuler les conditions de travail du revêtement : l'eau et un hydrocarbure agressif (toluène). Des modèles sont élaborés et décrivent de manière satisfaisante ces phénomènes de transfert. Dans le cas de l'eau, le processus de transfert par absorption est contrôlé par diffusion avec une diffusivité constante alors que le séchage est contrôlé par diffusion à l'intérieur du revêtement et par évaporation à la surface. La température a un effet considérable sur les cinétiques d'absorption et de séchage ainsi que sur les quantités d'eau absorbées et désorbées à l'équilibre. Lorsque le revêtement est en contact avec le toluène, le transfert par absorption présente une cinétique approximativement d'ordre zéro. Deux modèles numériques sont élaborés suivant deux approches différentes. La première approche admet que le processus d'absorption est composé de deux étapes successives : transfert du liquide dans la résine vitreuse suivant un déplacement d'un front de liquide avec vitesse constante puis transfert du liquide par diffusion dans la résine devenue élastomérique par la présence du liquide derrière le front. La seconde approche repose sur l'hypothèse que le processus est contrôlé par diffusion avec une diffusivité dépendante de la concentration et que la concentration à la surface varie avec le temps
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Hinchcliffe, Trevor Thomas. "Chiral side chain liquid crystalline polymers." Thesis, Heriot-Watt University, 1993. http://hdl.handle.net/10399/1404.
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Pickles, Matthew Jonathan. "Hydrodynamic erosion of coatings." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243503.
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Picot, Oliver. "Functional films and fibres based on liquid crystal coatings." Thesis, Queen Mary, University of London, 2015. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8844.
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This thesis aims to produce functional polymer fibres and films using liquid crystal networks or photoembossing. The work focuses on visual effects in fibres, optical sensing properties and, actuation and morphing properties. In the first part we focused on changing the perception of textiles by generating structural colours based on diffraction and/or reflection of light. For the former, a micro-structuring technique is combined with a contactless patterning technique: pulsed holography. The results show that diffractive features could be generated on static or moving polymer films allowing for large area patterning. The use of a contactless patterning technique also suggests its potential application for curved surfaces such as fibres. In the second approach, reflective colours are generated using a self-organising cholesteric liquid crystal (CLC) coating. The coating is applied in a one step process though spray coating of a liquid crystal monomer mixture on the polymer substrate followed by photopolymerization. Reflectivity measurements and optical microscopy show that a well-defined liquid crystalline and planar alignment is obtained. In the case of films, a strong angular dependent reflection is obtained. In comparison fibres shown lower reflectivity with an angular dependent colour in a single dimension along the fibre direction which originates from the planar cholesteric alignment on a curved surface. The second part of the project was aimed at detecting strain optically in polymer films and fibres. Here, we used the same process to produce reflective films and studied the optical response to uniaxial deformation. Results showed a colour shift as function of strain that was dependent on the mechanical behaviour of the substrate giving real time information of the deformation in the substrate. In the final part the thesis, we explored shape change in response to light of a bilayer photoresponsive film for adaptive textile applications. Here we showed that bending could be generated by coating a photoresponsive LC layer on an oriented polymer substrate. Bending is attributed to a photo induced contraction that occurs in the coating. The resulting response was strongly dependent on the substrate thickness and stiffness, thermo-mechanical properties and the concentration of chromophore in the LC layer.
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Bartoš, Radim. "Příprava a charakterizace oxidických vodivých vrstev." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2019. http://www.nusl.cz/ntk/nusl-401927.
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Liquid composition for antimony doped tin oxide solgel deposition was prepared. Anorganic precursors of tin and antimony were used (tin(IV) chloride, antimony(III) chloride). ATO nanoparticles were dispergated in composition. This composition was used for spincoating deposition of thin films. Composition was analyzed by thermal analysis TGA and DSC. Sheet resistence of prepared samples were examined by four probe sensing. RMS roughness and thickness was measured by profilometry. Samples were analyzed by scan electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Transmittance and haze were measured and calculated by UV-VIS spektrometry with integration sphere.
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Grundwürmer, Matthias. "Development and characterisation of liquid impact resistant sol-gel coatings." Düsseldorf VDI-Verl, 2008. http://d-nb.info/990760251/04.
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Žáková, Michaela. "Příprava transparentních oxidických vodivých vrstev materiálovým tiskem." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-449337.
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Thin transparent conductive layers containing ATO nanoparticles are a modern material that has found use in a wide range of optoelectronic applications. For liquid phase deposition there were designed and prepared compositions using a „brick and mortar“ approach combined templating agents. A sol-gel solution formed of inorganic precursors of tin chloride and antimony trichloride in the presence of ATO nanoparticles was mixed with a surfactant to improve the structure and wettability of applied films. Polyethylene glycol, polyoxyethylene (20)cetylether, sodium dioctylsulfosuccinate and polyvinylpyrrolidone were used as templating agents. Thin layers of these compositions were applied by the spin-coating method. Characterized parameters were resistivity, thickness and turbidity. A resul compositions showed relatively good electrical properties and high transparency and a potencial to be used for material printing.
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Najafi, Ali. "Application of Polymeric Ionic Liquid Solid-Phase Microextraction Sorbent Coatings and Ionic Liquid Stationary Phases for Liquid and Multidimensional Gas Chromatographic Techniques." University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1449846148.
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Ormerod, Andrew Paul. "The formation of chromonic liquid crystals by water-soluble azo-dyes." Thesis, University of Salford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261917.
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Sarma, Sreedhara. "Fluid Mechanics of High Speed Deformable Roll coating. An experimental and theoretical study of film thickness and stability in high speed deformable roll coating flow with Newtonian and non-Newtonian liquids." Thesis, University of Bradford, 2015. http://hdl.handle.net/10454/14842.
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Zhao, Qichao. "Ionic Liquid Materials as Gas Chromatography Stationary Phases and Sorbent Coatings in Solid-Phase Microextraction." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1320963975.
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Iglesias, Hernandez Luis. "Resonant microsystems for hydrogen gas detection without functionalized coating." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0112.
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Le dihydrogène, communément appelé hydrogène, est un gaz dangereux qui devient explosif au-dessus d'une concentration de 4% dans l'air. Par conséquent, de nombreuses applications pour lesquelles l'hydrogène est utilisé ou produit nécessitent des capteurs d'hydrogène pour s'assurer que cette limite n'est jamais atteinte. Ces applications comprennent la surveillance des déchets radioactifs, la production d'énergie propre ou plus généralement la surveillance des gaz industriels. La plupart des dispositifs de détection existants actuellement sur le marché sont basés sur l'utilisation d'un composé chimique ou d'une couche sensible spécifiquement conçue, qui dans la plupart des cas n'est pas stable dans le temps, généralement au bout quelques mois il y a une dégradation des propriétés de la couche ou du composé chimique. Cela a conduit au développement de méthodes qui reposent sur des mécanismes de détection physiques plutôt que chimiques pour la détection de l'hydrogène : ces méthodes ont l'avantage d'être stables sur des périodes beaucoup plus longues. Dans le contexte de la surveillance des déchets radioactifs, des travaux antérieurs avaient montré que les micropoutres non revêtue de couche sensible étaient capables de détecter l'hydrogène gazeux jusqu'à 0,01% en mesurant leur changement de fréquence de résonance. Les travaux de cette thèse prolongent cette étude en y ajoutant la capacité de distinguer l'hydrogène des autres gaz potentiellement interférents. Dans le cas des micropoutres, la discrimination des gaz est réalisée en mesurant non seulement la masse volumique du gaz mais aussi sa viscosité grâce à la mesure simultanée de la fréquence de résonance et du facteur de qualité. Des transducteurs ultrasoniques micro-usinés capacitifs (CMUT) ont également été utilisés comme alternative aux micropoutres. Avec les CMUT, la vitesse du son et l'atténuation acoustique ont également été mesurées à l’aide d’un montage de type mesure de temps de vol au lieu des mesures du spectre du dispositif à la résonance. Dans le cas de la mesure de l'atténuation, une méthode permettant d'obtenir une bonne sélectivité de la détection d'hydrogène vis-à-vis de gaz interférents tels que le dioxyde de carbone et le méthane a été développéeHydrogen is a hazardous gas that becomes explosive above a concentration of 4% in air. As a result, many applications where hydrogen is either used or produced require hydrogen sensors to ensure that this limit is never reached. These applications include radioactive waste monitoring, clean energy production or more generally industrial gas monitoring. Most existing sensing devices currently on the market are based on the use of a specifically engineered chemical component or film, which in most cases is not stable over time, lasting usually a few months. This has led to the development of methods that rely on physical sensing mechanisms rather than on chemical ones for the detection of hydrogen: these methods have the advantage of being stable over much longer periods of time. In the context of radioactive waste monitoring, previous work has shown that uncoated (no chemical film) microcantilevers are capable of detecting hydrogen gas up to 0.01% by measuring their change in resonant frequency. This work extends this study by adding the ability to distinguish hydrogen from potential interfering gases. In the case of microcantilevers, gas discrimination is achieved by measuring not only the density of the gas but also its viscosity with the measurement of both the resonant frequency and the quality factor. Capacitive micromachined ultrasonic transducers (CMUTs) have also been used as an alternative to microcantilevers. With the CMUTs, both sound velocity and acoustic attenuation have been measured by a time of flight setup instead of device measurements at resonance. In the case of attenuation measurement, a method for obtaining good selectivity of hydrogen measurement against interfering gases such as carbon dioxide and methane has been developed
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Siegert, Roberto. "A novel process for the liquid feedstock plasma spray of ceramic coatings with nanostructural features." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=980671728.
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Walesch, Dieter. "Étude de la mise en suspension de poudres d'aluminium dans un milieu liquide en vue de réaliser des dépôts d'aluminium sur tôles galvanisées." Valenciennes, 1997. https://ged.uphf.fr/nuxeo/site/esupversions/9a67be5e-54d4-431d-be0f-fe42d2dd61ca.
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Bien que les techniques de la galvanisation soient anciennes, on constate régulièrement des évolutions dans le domaine grâce aux techniques connexes qui progressent. Se basant sur son savoir-faire, la fabrique de fer de Maubeuge a imaginé un procède alliant la flexibilité des lignes de peinture au principe du Slurry Coating. Ce travail est particulièrement consacré au système aluminium déposé sur tôle galvanisée. Nous avons été amenés à exploiter quelques théories concernant les formulations des mélanges de poudres. Elles ont été en grande partie empruntées aux formulations des barbotines céramiques. Nous préciserons toutefois que les synthèses de nos propres mesures sont venues enrichir les données bibliographiques. Les structures observées sont particulières. La complexité des chemins de diffusion que nous essayons d'interpréter résultent de fronts de réactions très instables. Les couches d'aluminium, de faibles épaisseurs, engendrent lors du recuit des fronts de diffusion multiples. Les équilibres se modifient, certaines phases apparaissent pour disparaitre aussi rapidement.
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Kong, Yiyang. "Encapsulation of room temperature ionic liquids by miniemulsion polymerisation for application in low-emitting latex coating." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/37601/.
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Latex coating has gained increasing attention. It is prepared by mixing latex, a dispersion of polymer particles in water, with pigments, fillers, and additives. As water is used as solvent, emission of VOCs can be minimised. However, coalescing agent emission and excessive surfactant residual hinder its further applications. To solve these two problems, we tried to use room temperature ionic liquid (RTIL), a potential multi-functional additive with non-volatility, to replace coalescing agent, and employed silica nanoparticle as emulsifier to stabilise the latex. The preparation of latex containing 1-octyl-3-methylimidazolium hexafluorophosphate (C8mimPF6), the target RTIL in this study, could be achieved by encapsulating C8mimPF6 inside particles via miniemulsion polymerisation. Two kinds of emulsifiers, surfactant and silica nanoparticle were employed to stabilise miniemulsion/latex. To achieve this encapsulation, three steps were carried out in succession: preparation of miniemulsion, miniemulsion polymerisation, and characterisation of latex containing C8mimPF6. Factors, especially C8mimPF6, on initial droplet size and stability of miniemulsion, yield and stability of polymerisation process, and final functionality of latexes were systemically investigated. For miniemulsion stabilised by surfactant, sodium dodecyl sulfonate (SDSO), initial droplet size decreased apparently with the addition of C8mimPF6 up to 1 wt% due to the effect of C8mimPF6 on oil phase viscosity and interfacial tension. During storage, C8mimPF6 above 10 wt% led to the frequent coalescence of droplet as it decreased the absolute zeta potential. During polymerisation, when initiated by hydrophobic 2, 2-azobis (isobutyronitrile) (AIBN), C8mimPF6 had a promoting effect on the reaction rate at low concentrations, but this effect might reverse upon certain C8mimPF6 concentrations, e.g. 10 wt%; while initiated by hydrophilic hydrogen peroxide/ascorbic acid (H2O2/AAc), this promoting effect faded even at low C8mimPF6 concentrations. The different limiting factors, kinetic or transfer of radicals, might determine the reaction rate with different types of initiator. The final particle size depended on the nucleation mechanism as well as the coalescence of droplets/particles during polymerisation. For the final latex, C8mimPF6 promoted the decrease in glass transition temperature (Tg) and the deformation of particles, due to its function as an external plasticiser with low Tg and compatibility with poly (methyl methacrylate) (PMMA) inside particles; the film became more flexible and had better thermal stability in the present of C8mimPF6. To solve excessive surfactant residual, silica nanoparticles were employed as emulsifiers to stabilise miniemulsion. Adding 1 wt% C8mimPF6 resulted in a sharp decline in droplet size, due to the combined effects of C8mimPF6 on the viscosity of oil phase and interfacial tension. Because of the low absolute zeta potential, creaming or sediment occurred at different C8mimPF6 concentrations, determined by the density difference between the oil and water phases. During polymerisation, a higher yield could be achieved by AIBN, compared with H2O2/AAc. The change of C8mimPF6 concentration had a greater impact on product stability e.g. only above 10 wt% C8mimPF6, stable products could be achieved. For product yield, there was only small effects, varying from 85 wt% to 91 wt% with C8mimPF6 changing from 0 to 30 wt%. For the final latex, the Tg of the obtained polymer decreased with the increase of C8mimPF6 concentration, indicating its function as an external plasticiser, but deformation of particles was limited, probably due to obstacles of silica nanoparticles on the surface of particles. Compared with bulk PMMA, films containing C8mimPF6 had a better thermal stability at temperatures ranging from 300 oC to 450 oC.
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Santos, Franceska Anna. "Phase Behavior and Rheology of Latex, Thickener, Surfactant Mixtures and Liquid Crystal Based Compositions for Printing High-Efficiency Flexible Electronics." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1151.
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This project consists of two parts. One area of focus in the first part is understanding the interactions between a non-ionic, block copolymer type dispersant and hydrophobically-modified, ethoxylated urethane (HEUR) associative thickeners in water. The dispersant was mixed at various concentrations (0-2% by weight) with HEUR thickeners at 1% by weight concentration in the aqueous medium. This study is an integral part of our attempts to determine mechanisms of viscosity drop when colorant dispersions are added to latex tint base formulations thickened with associative thickeners. One of the HEUR thickeners is a product that has been available for over three decades (HEUR RM-825), whereas the other, HEUR RM-995 is a product recently introduced to minimize the tint base viscosity drop. The old HEUR showed a definitive viscosity maximum as a function of the dispersant concentration. However, the new generation product did not indicate a viscosity maximum within the dispersant concentration range studied; instead it showed a small, but linear increase in viscosity as dispersant level was increased.
The next area of focus was on understanding the phase behavior, rheology, and interactions between polymer latex particles and a hydrophobically-modified, ethoxylated urethane (HEUR) associative thickener in water. The influence of the addition of surfactant in some of the systems was also studied. Several types of dispersions were made using two types of polymer latex, two associative thickeners, and two surfactants. Mixtures containing a small particle size acrylic latex and HEUR RM-825 exhibited the most interesting and complex phase behavior and rheology. In experiments wherein the latex particle volume fraction was kept constant, the addition of HEUR caused stable, followed by phase separated (syneresis) and stable mixtures as HEUR concentration was increased. The observed phase behavior is consistent with previous work reported by other investigators. However, detailed rheological data on systems such as these have not been reported, and this report presents the rheological data and correlate rheology with the phase behavior. The stable latex-HEUR mixtures at low HEUR levels show shear-thinning viscosity with well-defined low-shear Newtonian plateaus. As HEUR level is increased wherein syneresis is observed, erratic rheological profiles with shear-thickening are observed. When HEUR level is increased to a region where no syneresis is observed, low shear Newtonian plateaus re-appeared albeit at higher viscosities. The effects of added non-ionic and anionic surfactants on the dispersion are also studied.
The main focus of the second part of this project is hybrid organic-inorganic photovoltaics. They have been the focus of recent studies due to their promising use in low-cost, flexible electronics, which can be processed from solution by printing and coating techniques. Understanding the rheology of these nanocomposites is essential in controlling shear flows during printing and application processes. Through rheology, we can determine different properties of poly(3-hexylthiophene) and dodecanethiol (DDT) modified zinc oxide (ZnO-DDT). Semiconductor nanowires such as ZnO have rigid or rod-like macromolecule geometry. Therefore, they have a tendency to have a lytropic liquid crystal (LLC) phase. LLC orders occur spontaneously in solutions with rod-shaped or anistropic objects from isotropic phase to nematic phase above a critical volume fraction which was studied using ZnO-DDT. The shear-induced alignment of the liquid crystal molecules was analyzed, serving as a guide for LLC printing. Furthermore by using this nanocomposite we are able to induced gelation using the ZnO-DDT nanowires in what is considered as a “good solvent,” dichlorobenzene. The kinetics of this gelation process was determined to be of first-order reaction kinetics. Furthermore, a mechanism of this gelation process is also presented.
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Suffield, Sarah Rose. "Modeling the flow of a liquid droplet diffusing into various porous media for inkjet printing applications." Online access for everyone, 2008. http://www.dissertations.wsu.edu/Thesis/Spring2008/s_suffield_041808.pdf.
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Piwonski, Michael. "Keramische Membranen auf Basis LPS-SiC: Schlickerentwicklung und Beschichtungsverfahren." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1138049474013-12420.
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Die Filtration unter aggressiven Einsatzbedingungen, z.B. Einsatz in korrosiven Medien, Abgasfiltration, stellt besondere Anforderungen an das Filtermaterial. Sogenanntes "Liquid Phase Sintered Silicon Carbide" (LPS-SiC) erfüllt die Anforderungen sehr gut. Deshalb bestand das Ziel der Arbeit besteht darin, erstmals aus LPS-SiC asymmetrische keramische Membranen (grobporöses Substrat mit dünner, feinporiger Membran) herzustellen. Als Additivsystem fanden Yttriumoxid und Aluminiumoxid Verwendung. Es wurde Siliciumcarbid der Körnung F1200 auf Substrat der Körnung F500 abgeschieden. Dem Herstellungsverfahren kommt für die Qualität der Membran eine große Bedeutung zu. Daher wurden in dieser Arbeit folgende Beschichtungsmethoden untersucht, um die optimale Methode zu identifizieren: Tauchbeschichtung, elektrophoretische Abscheidung, Druckfiltration und Einsatz von Transfertapes (Transfertapes: Mischung aus Polyacrylatkleber und Pulver). Im Mittelpunkt stand dabei die Druckfiltration. Hierfür wurde eine neue Apparatur konzipiert und aufgebaut. Für die schlickerbasierten Methoden wurde ein wässriges System entwickelt, bei dem auf den Einsatz von organischen Hilfsstoffen verzichtet werden konnte. Die elektrostatische Stabilisierung konnte durch gezieltes Anlösen von Yttriumoxid, Ausfällen von feinskaligem Yttriumhydroxid und Belegung des Siliciumcarbids mit dem Yttriumhydroxid erreicht werden. Die Elektrophorese führte zu keinen befriedigenden Ergebnissen aufgrund des undefinierten spezifischen Widerstandes des Substrats (siehe Dissertation Jan Ihle, Bergakademie Freiberg 2004). Die Druckfiltration erwies sich als das geeignetste Verfahren. Mit ihr konnten ohne Einschränkungen hochwertige Membranen erzeugt werden. Druck und Zeit sind bei gegebenen Feststoffgehalt frei wählbar. Der Druck wurde zwischen 2*10E4 und 1*10E5 Pa variiert. Höherer Druck führte zu feineren Porengrößen (mittlere und maximale Porengröße). Mit der Druckfiltration konnten Membranen ohne makroskopische Defekte erzeugt werden. Sie führte im Vergleich aller Verfahren zu der geringsten Rauhtiefe der Membranen. Die Tauchbeschichtung ließ sich in diesem System nur über den Feststoffgehalt steuern. Membranen aus der Tauchbeschichtung wiesen makroskopische Fehler (große oberflächliche Poren) auf. Die Methode führte hinsichtlich Porengrößen und Rauhtiefe zu den schlechtesten Werten. Die Transfertape-Methode als neuartiger Ansatz erwies sich für das LPS-SiC System als noch nicht ausgereift. Das direkte Bekleben der Substrate war möglich. Hinsichtlich der Membrandicke sind aber Grenzen bei ca. 50 µm gesetzt. Darüber hinaus reißen die Membranen. Es wurden Schwankungen in der Entbinder- und Sinterschwindung verzeichnet. Weiterhin werden große Hohlräume im Substrat nicht von den Transfertapes abgeformt. Beide Effekte erhöhen die Spannungen beim Sintern, so dass bei geringeren Schichtdicken Risse entstehenSilicon Carbide (SiC) fulfills many requirements, e.g. a high robustness in terms of corrosion, which makes it a suitable Material for ceramic membranes. The aim of this work was to produce ceramic membranes out of porous liquid phase sintered Silicon Carbide (LPS-SiC). As additives Alumina and Yttria were used. The SiC based on commercial abrasive powders F1200 (Membrane) and F500 (Substrate). Different techniques of membrane formation were applied in order to find the optimum processing procedure: Dip Coating, Electrophoretic Deposition (EPD), Pressure Filtration and the usage of so called Transfer Tapes, a blend of Polyacrylate and ceramic powders). For the slip based methods a water based system was developed without the need of organic additives. A pure electrostatic stabilization was facilitated by solving Yttria with Hydrochloride Acid and precipitation, resulting in the coverage of the SiC particles with finely dispersed Yttria. The EPD was not successful due to a undefined specific resistance of the substrate. The pressure filtration turned out to be the best, most versatile method, leading to defect free membranes with the lowest measured surface roughness. The pressure ranged between 2*10E4 and 1*10E5 Pa. Higher pressure lead to finer pores. The Dip Coating was controlled only by the solids content. Membranes by Dip Coating showed macroscopic defects. As a new concept for ceramic membrane fabrication the Transfer Tapes needed further investigation. The direct gluing on the substrate was possible. The thickness of the membrane was limited to 50 microns in order to keep free of cracks. The Transfer Tapes exhibited pronounced fluctuations in the debinding and sintering shrinkage, leading to increased tension during sintering. Furthermore cavities, (e.g. big pores) were bridged. Both effects lead to increased tension during sintering
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Соболєва, М. І. "Леговані та гібридні кальцій фосфатні покриття на Ti6Al4V субстратах для біомедицини." Master's thesis, Сумський державний університет, 2019. http://essuir.sumdu.edu.ua/handle/123456789/75820.
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У ході виконання магістерської роботи було отримано біокомпозитні покриття на основі гідроксиапатиту (HA) та хітозану (CS) з заданими додатковими протимікробними властивостями та здатністю до пролонгованого вивільнення лікарських засобів. Досліджена структура, морфологічні особливості та фізико-хімічні властивості з застосуванням сучасних методів дослідження: XRD, RFA, SEM, HPLS.
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Halthur, Tobias. "Multilayer Structures for Biomaterial Applications : Biomacromolecule-based Coatings." Doctoral thesis, KTH, Chemistry, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-551.
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The cellular response to a biomaterial, such as a dental implant, is mainly governed by the surface properties, and can thus be altered by the introduction of a surface coating. In this thesis the buildup of a biomacromolecule-based coating formed by layerby-layer (LbL) deposition of the charged polypeptides poly(L-lysine) (PLL) and poly(L-glutamic acid) (PGA) has been studied. In an attempt to make these coatings bioactive and useful for bone-anchored implants, an amelogenin protein mixture (EMD), has been immobilized in these thin polyelectrolyte multilayer (PEM) films. Multilayers were also built by LbL deposition of the natural biomacromolecules collagen (Col) and hyaluronic acid (HA). Multilayer films of these two extra-cellular biomacromolecules should be of interest for use as a scaffold for tissue engineering.
The buildup of the multilayer films has been followed in situ, using ellipsometry, quartz crystal microbalance with dissipation (QCM-D), and dual polarization interferometry (DPI). The studied PLL/PGA multilayers were found to be highly hydrated, and to exhibit a two-regime buildup behavior, with an initial “slow-growing” regime, and a second “fast-growing” regime with a linear growth in film thickness and more than linear growth in mass. A net diffusion of polypeptides into the film during the buildup led to an increase in density of the films for each layer adsorbed. A change in density was also observed in the Col/HA film, where HA penetrated and diffused into the porous fibrous Col network.
The formed PLL/PGA films were further found to be rather stable during drying, and post-buildup changes in temperature and pH, not losing any mass as long as the temperature was not raised too rapidly. The film thickness responded to changes in the ambient media and collapsed reversibly when dried. A swelling/de-swelling behavior of the film was also observed for changes in the temperature and pH.
The EMD protein adsorbed to silica surfaces as nanospheres, and could by itself form multilayers. The adsorption of EMD onto PLL/PGA multilayer films increased at lower pH (5.0), and EMD could be immobilized in several layers by alternate deposition of EMD and PGA.
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Aranga, Raju Arun Prakash. "Production and applications of graphene and its composites." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/production-and-applications-of-graphene-and-its-composites(f9000ac1-84ad-41e3-872b-4d7afc80a509).html.
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Graphene, a single layer of graphite, owing to its excellent mechanical, electrical, and thermal properties, has evolved as an exceptional nanomaterial in the past decade. It holds great promise in developing various novel applications from biomedical to structural composites. However, several challenges remain in realising the great potential of this material; one being the bulk scale production of graphene. This thesis has been concerned with production of pristine few-layer graphene (FLG) using liquid phase exfoliation (LPE) of graphite in various solvent media and exploring the applications of graphene-based composite coatings as optical Raman-strain sensors. LPE of natural graphite using bath sonication was used to produce highly stable pristine FLG in 1-methyl-2-pyrrolidinone (NMP) and N,N-dimethylformamide (DMF). Atomic force microscope (AFM) was used to analyse the exfoliation efficiency and lateral dimensions, while Raman spectroscopy provided an insight about the quality of the graphene flakes. Moreover, the potential for dynamic light scattering (DLS) as an efficient in situ characterisation technique for estimating the lateral dimensions of graphene flakes in dispersions was demonstrated. LPE was also employed to explore various routes to produce pristine graphene in aqueous media which can be used for toxicity studies. Aqueous dispersions were prepared by a solvent exchange method of graphene originally in organic solvents (NMP and DMF) using dialysis, achieving 0.1 v/v% organic solvent levels. Pristine aqueous graphene dispersions were also prepared by directly exfoliating graphite in biocompatible surfactant (TDOC- Sodium taurodeoxycholate) and biomolecules (Phosphatidylcholine and human serum albumin) solutions. Cell culture studies by collaborators revealed that solvent-exchanged and TDOC-exfoliated pristine FLG displayed minimal toxicity and albumin-exfoliated FLG hardly any cytotoxicity, whereas phosphatidylcholine-exfoliated FLG was cytotoxic. Raman spectroscopy is a well-established technique used to study the local deformation of carbon-based composites by following the shift rates of the Raman 2D band with strain. Raman active strain coatings were produced from epoxy composites made with the FLG produced by LPE in organic solvents and by electrochemical exfoliation method. The deformation experiments on these coatings revealed little or no strain sensitivity, due to several factors such as length of flakes, processing history, graphene loading, defects in graphene and alignment of flakes within the composites. As an alternative, composite coatings made from chemical vapour deposition (CVD) graphene were investigated. Excellent strain sensitivity was observed upon various cyclic deformational sequences and Raman mapping over 100 × 100 µm area. In comparison to the commercially available wide area strain sensors, CVD graphene composite coatings with a calculated absolute accuracy of ~ ± 0.01 % strain and absolute resolution of ~ 27 microstrains show promise for wide area Raman-based strains sensors.
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Louie, Jennifer Sarah. "Fouling-resistant coatings for reverse osmosis membranes : gas and liquid permeation studies on morphology and mass transport effects /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Stuttle, Christopher. "The electrodeposition of tin coatings from deep eutectic solvents and their subsequent whisker growth." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/17961.
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Tin electrodeposits produced from aqueous electrolytes are frequently used within the electronics industry due to their high solderability and corrosion protection. One limitation to using these deposits is their spontaneous formation of long conductive filament whiskers. These whiskers grow post-electrodeposition and increase the risk of unwanted electrical shorts within electronic devices. In this thesis, tin electrodeposits produced from a proprietary bright acid Tinmac electrolyte, currently used in industry, were studied. Electrodeposits were produced using a range of current densities with and without agitation and were characterised with respect to crystallographic orientation, topography and surface finish. Moreover, the intermetallic compound (IMC) growth produced at the copper substrate-tin coating interface was assessed over a period of time as its growth is considered to be a significant driving force behind whisker formation. In addition, a technique for the electrochemical anodic oxidation of tin electrodeposits on copper substrates was developed. This technique was used throughout this project for the study of IMC growth from tin electrodeposits as it was able to effectively remove the tin whilst leaving the IMCs and substrate unaffected. Ionic liquids exhibit promising electrochemical characteristics for electrodeposition but are still not widely utilised in industry. Their ability to deposit tin coatings has been studied in the present investigation. Trials concentrated on process optimisation to produce uniform electrodeposits by varying current density, SnCl2.2H2O concentration, and electrolyte composition. These deposits were then characterised and compared to tin coatings of similar thickness produced from Tinmac with respect to topography, surface finish, crystallographic orientation, IMC growth, and whisker propensity. Electrodeposits produced from the ionic liquid electrolyte exhibited a different crystallographic texture, topography, and IMC growth compared to those produced from Tinmac. Moreover, the deposit produced from the ionic liquid featured increased whisker growth compared to those produced from Tinmac, but in a wider context, far less growth than conventional tin electrodeposits in the literature. In addition, by exploiting other electrochemical characteristics of ionic liquids, such as their large potential window, future work may be able to produce novel tin or tin alloy electrodeposits which may further reduce the whisker propensity of deposits produced in this investigation.
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Naidji, Bouzid. "Influence de la pression sur le phénomène de cavitation en milieu liquide ionique sous irradiation ultrasonore basse fréquence." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCD030.
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L’objectif de ces travaux est d’étudier l’influence de la pression sur le phénomène de cavitation. Lors de la propagation d’une onde acoustique en solution, celle-ci peut entraîner la rupture des forces de cohésion du liquide menant ainsi à la formation de bulles de cavitation. Alimentées par les vapeurs de solvant et les gaz dissous, ces bulles vont croître puis imploser violemment après avoir atteint une taille critique. Pour l’étude des procédés électrochimiques assistés par ultrasons, le contrôle de la cavitation s’est avéré intéressant. En dégazant les liquides ioniques, i.e. limitation des gaz dissous et tension de vapeur des solvants très faible, il a été possible de contrôler le phénomène de cavitation. Les résultats montrent une diminution importante de la cavitation pour des pressions inférieures à 60 kPa. Les contributions respectives de la cavitation et des courants acoustiques dans l’agitation hydrodynamique globale ont pu être déterminées grâce à des techniques électrodiffusionnelles. Un milieu cavitant permet d’augmenter l’agitation globale d’environ 30 % par rapport à un milieu monophasique (sans cavitation) dans le cas d’une irradiation ultrasonore basse fréquence. L’influence de la cavitation sur le greffage des monocouches auto-assemblées (SAMs) et des revêtements électrochimiques d’argent et de cuivre dans les liquides ioniques a ainsi pu être évaluée. Dans le cas des SAMs, le phénomène de cavitation s’est révélé bénéfique vis-à-vis de la cinétique de greffage des films organiques et de l’orientation des chaines carbonées à la surface du substrat. En effet, pour 15 minutes de traitement sous ultrasons sans cavitation, le taux de blocage électrochimique est 3,6 fois plus important qu’en condition silencieuse. En milieu cavitant, ce taux de blocage augmente encore de 50 %. Concernant les revêtements électrolytiques une diminution de la taille de cristallite a été observée quand l’activité cavitationnelle augmente. Effectivement, il a été constaté une réduction de 30 % pour les revêtements de cuivre et de 50 % pour l’argentThe aim of this study is to investigate the influence of pressure on cavitation phenomenon. During propagation of an acoustic wave in solution, cohesion forces within the liquid can break leading to formation of cavitation bubbles. Fed with solvent vapors and dissolved gases, these bubbles grow and implode violently after reaching critical size. For the study of electrochemical processes assisted by ultrasound, cavitation control is interesting. By limiting the presence of dissolved gases and using low vapor pressure solvents, it was possible to control cavitation phenomenon. Results show big decrease in cavitation for pressures below 60 kPa. Respective contributions of cavitation and acoustic streaming within global hydrodynamic agitation have been determined thanks to electrodiffusional techniques. A cavitating medium enables increase in global agitation of about 30% in comparison to a monophasic medium (without cavitation) in the case of a low frequency ultrasound irradiation. Influence of cavitation on self-assembled monolayers (SAMs) grafting and electrochemical coatings of silver and copper in ionic liquids has been assessed. In the case of SAMs, cavitation is beneficial towards organic film grafting kinetics and carbon chain orientation on the surface. Indeed, for 15 minutes modification under ultrasound irradiation without cavitation, electrochemical blocking rate is 3.6 times higher than in silent conditions. With cavitation, this blocking rate shows an additional 50% increase. Concerning electrolytic coatings, a decrease in crystallite size is evidenced with increase in cavitation activity. Indeed, a decrease of 30% and 50% was observed for copper and silver coatings, respectively
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Jiang, Chengliang. "Germania-based Sol-gel Coatings and Core-shell Particles in Chromatographic Separations." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7683.
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Chapter one reviewed the development of sol-gel stationary phase for gas chromatograph (GC). Inorganic sol-gel precursor creates the substrate support for stationary phase bind to silica surface through the condensation of silanol groups, the rough surface with enhanced surface area enlarger the capacity of the sol-gel stationary phase, the porosity of sol-gel structure decreases the mass transferring coefficient, the term C in Van Deemter equation, which makes sol-gel stationary phase thicker coating up to 1 um but keeps the high resolution for gas chromatography. Chemical bound stationary phase significantly improve GC column with better thermal stability and solvent stability. Partial derivatizations of known polymers have not increased the column performance but remained at the same level of 3200 plates per meter. The sol-gel chemistry with essential structure rebuilding will make sol-gel stationary phase to a new level.
The chapter two reported the non-silica-based metal alkoxide oxide as the new building block, cooperated with known polymer poly(dimethyldiphenylsilanoxan), developed the original nonpolar feature of the stationary phase to broad the polarity from the nonpolar to extreme polar, overcome the thermal stability for other types of polar column. The theoretical plate number reached the 3200 plates per meter, and the optimized plate number arrived at the top level at 3800 plates per meter. The basic recipe and preparation of sol-gel process were verified by tungsten alkoxide incorporated with poly(dimethyldiphenylsilanoxan) as the stationary phase which arrived the same plate number level at 3800 per meter.
Chapter three demonstrated the preparation of core-shell particle for HPLC. Conventional silica core particles were prepared with stÖbe methods. The extended layer of germanium oxide coating was made with acid and alkaline as a catalyst. EDS characterize the extended layers of germanium oxide has been coated at ratio 12/1(Ge/Si). Then the carbon loading with C 18 for surface derivatization were also confirmed with EDS testing. 2 um core-shell particles were successfully prepared from the external composition (1.7 um core, 0.3 um shell). The function of the core-shell particles was slurry packed with 5cm regular steel column and the capillary column with sol-gel frit. The preliminary HPLC testing showed the core-shell particles had more retention ability compare with 4 um commercial core particles. The backpressure of the short steel column and capillary both were beyond the pressure limit of conventional HPLC pump.
Chapter three demonstrates the new ideal of the surface sol-gel process for GC stationary phase. Without the catalyst, the sol solution has constant viscosity and gelation time is much longer, the sol-gel reaction was taking on the silica surface only, to accomplish the thinner coating for sol-gel stationary phase. From the retention time of the grob mixture, the surface sol-gel coated 2 meters of column acquired the half retention time, grob mixture analytes were eluted within 7 minutes, compared with conventional sol-gel coated column eluted within 14 minutes. Without the TFA as the catalyst, the sol-gel matrix may not form effective surface area and porosity to support the functional polymer for separation, the column performances were two third of the protocol column, at 1500-2500 plate number per meter. The coating results proved the sol-gel stationary phase could be fulfilled with diluted sol solution by static coating. Basic parameters for dynamic coating and static coating with conventional coating and surface sol-gel were acquired for further development. The germania and niobium precursor is highly active, the water amount in the solvents used as received without drying process can meet the surface sol-gel coating without precipitates and gelation formed before finishing coat.
For germania -PDMDPS column, thermal stability is very important because of the temperature for remaining the low residual OH- group in silica and germania film at 350 °C.
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Pierson, Jean-Lou. "Traversée d’une interface entre deux fluides par une sphère." Phd thesis, Toulouse, INPT, 2015. http://oatao.univ-toulouse.fr/15754/2/Pierson_2_sur_4.pdf.
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Cette thèse a pour objectif de comprendre la dynamique d’une sphère traversant une interface liquide-liquide. Cette situation, se rencontre dans de nombreuses applications, allant du cycle du carbone dans l’océan (sédimentation de neige marine), aux procédés d’enrobage, en passant par la détection de phase dans l’industrie pétrolière. Pour étudier cette configuration, trois approches sont privilégiées. Un dispositif expérimental muni d’une caméra haute fréquence est utilisé de manière à explorer la dynamique conjointe de la sphère et de l’interface sur une large gamme de paramètres. Le couplage entre une méthode Volume of Fluid (VoF) et une méthode de frontières immergées (IBM) est réalisé et validé dans le but de simuler numériquement ce problème. Enfin des modèles théoriques sont mis en place de manière à interpréter physiquement les différents comportements observés. Ces trois démarches complémentaires permettent de caractériser le passage d’une configuration de flottaison à l’entraînement colonnaire notamment en fonction du rapport entre effets gravitationnels et capillaires. La dynamique de la colonne emportée est très riche (instabilité capillaire, visqueuse, fragmentation, ...). Le bon accord entre les expériences et les simulations numériques permet d’évaluer avec confiance l’influence de chaque paramètre sans dimension (au nombre de 5) à l’aide d’une étude paramétrique numérique.