The engineering of a component’s surface is of remarkable importance, it allows applications that surpass what is achievable by the substrate alone by improving surface properties such as hardness, wear and corrosion resistance and even aesthetic value. This project focuses on obtaining bronze coatings through the diffusion of electrodeposited tin on copper via heat treatment. Specifically, the single phase α is targeted due to its attractive properties. Determining the correct heat treatment parameters is crucial since only a specific range of compositions lead to the formation of the desired microstructure and, consequently, properties. The diffusion of a thin coating of tin onto copper often leads to the formation of undesirable features: small craters containing different phases than the one targeted. In the present work, the diffusion behavior of tin-copper couple was investigated; a numerical model was developed to predict the composition profile after heat treatment, which agrees with experimental observations; and the mechanism for the formation of undesirable surface craters during heat treatment was studied and the probable solution proposed. / February 2017

This thesis mainly consists of two parts, the synthesis of several kinds of technologically interesting crystalline metal oxide nanoparticles via high temperature nonaqueous solution processes and the formation of core-shell structure metal oxide composites using some of these nanoparticles as the core with silica, titania or polymer as shell via a modified microemulsion approach. In the first part, the experimental procedures and characterization results of successful synthesis of crystalline iron oxide (Fe3O4) and indium oxide (In2O3) nanoparticles are reported. Those nanoparticles exhibit monodispersed particle size, high crystallinity and high dispersibility in non-polar solvents. The particle size can be tuned by the seed mediated growth and the particle shape can also be controlled by altering the capping ligand type and amount. The mixed bi-metal oxides such as cobalt iron oxide and lithium cobalt oxide will be discussed as well. In the second part, the synthesis and characterization of various surface coated metal oxides, including silica, titania and polymer coated nanocomposites are reported. The silica coating process is presented as a highlight of this part. By using a microemulsion system, core-shell structure silica coated iron oxide and indium oxide nanocomposites are successfully prepared. Furthermore, the thickness of the silica coating can be controlled from 2 nm to about 100 nm by adjusting the reaction agents of the micelle system. By extending the procedure, we will also discuss the titania and polymer coating preparation and characterization.

Bakgrund: F.O.V Fabrics har fått förfrågningar från sina kunder angående en beläggning som idag enbart finns pigmenterad. Kunder har efterfrågat en transparent variant av denna, vilken företaget nu vill undersöka möjligheterna för att förverkliga. Beläggningen skall bibehålla uppsatta kvalitetskrav. Syfte: Att försöka ta fram en transparent beläggning som bibehåller sina egenskaper gällande vattentäthet samt ånggenomsläpp. Metod: Laborationer har utförts både i liten och stor skala på Textilhögskolans färg- och beredningslabb. F.O.V har utifrån de småskaliga testerna, valt ut några prover, vilka vi tillsammans gått vidare med att testa storskaligt på Textilhögskolans labb. Kvalitetstester har sedan utförts på F.O.V. Huvudresultat: Som svar på vår problemformulering, har vi efter utförd undersökning, kommit fram till att vi, utifrån de givna parametrar vi tillhandahållit, inte går att få fram en transparent beläggning, vilken uppfyller de önskvärda kvalitetskraven.Ett viktigt resultat som dock framkommit av undersökningen var att om materialet bestryks med tillräcklig mängd pasta, räcker det med två lager, vilket är en stor kostnadsfördel gentemot trelagersbestrykning. / <p>In collaboration with F.O.V Fabrics, we have tried to develop a transparent coating for work wear, which is presented in this thesis.The testing of three new coating recipes, should maintain their properties in being water resistant and breathable. The shell material consisted of polyester, but since the content of classification is secret, we do not fully know how the fabric has been pre-prepared.Our small-scale tests and later on also the large-scale tests took place at the Swedish School of Textiles in Borås, where we also consulted our tutor Catrin Tammjärv and Jesper Carlsson from F.O.V Fabrics.We laborated with different parameters, and with both foam- and paste coatings. The final tests were further quality tested at F.O.V Fabrics. The results sometimes surprised us, as well as Jesper from F.O.V Fabrics. Our final results are to be followed in this thesis.</p><p>Program: Textil produktutveckling med entreprenörs- och affärsinriktning</p>

In the railway industry, and premium luxury and super sports sectors of the automotive industry, traditional cast iron brake discs are gradually being replaced with advanced composites such as carbon fibre reinforced carbon silicon carbide (Cf/C-SiC). These materials offer the ability to operate at higher temperatures, whilst displaying improved friction performance, and vastly reduced wear rates. Their primary benefit comes from being approximately one third of the density of the incumbent material used in the industry, grey cast iron (GCI), a cast iron with a high proportion of graphite flakes formed during solidification. This reduced density means that brake discs manufactured from Cf/C-SiC materials are a highly suitable proposition for a future automotive market, where weight saving in an attempt to meet ever restrictive CO2 emissions is a must. The understanding surrounding the friction mechanisms involved with these new materials has been lacking, until recently, with the majority of the international research focused on the manufacturing methods. Research has shown that friction performance, particularly bedding friction, is highly dependent on the successful formation of a friction transfer film (FTF) at the surface of any disc, comprised from wear debris from both the disc and pad. Prior research carried out at Loughborough University has identified that Cf/C-SiC materials do not readily form such a layer, as might be seen on a GCI equivalent, due to the intrinsically heterogeneous nature of the composite material.

Ruminants possess a unique digestive system. Using the high metabolic potential of the symbiotic microflora of the rumen, ruminants are capable of digesting plant material and obtaining nutrients and energy from this process. Because of the ruminal fermentation, the most bioactives are not stable in the harsh ruminal environment. Therefore there is a need to improve the bioavailability of a bioactive by protecting it from the ruminal digestion. The formulation of protected bioactive can be delivered in the rumen in a controlled manner and over a long period of time. In this project the degree of rumen protection was estimated using model substrates (sugar pellets and granules). These materials were coated with the pH-sensitive polymer Eudragit E. The model bioactive (phloridizin) was coated using the coating methodology adopted from exploratory studies with model substrates. The bioavailability of protected (coated) phloridizin was assessed by administering directly into the abomasum of fistulated cows. Formulation of protected phloridizin was used to demonstrate the feasibility of bioactive controlled delivery based on ART ( Active Rumen Technology ). This technology uses an elevated gas pressure created by a hydrogen-producing cell to drive a plunger which extrudes bioactive formulation from an intraruminal controlled-release device. Four groups of devices filled with formulation containing different amounts of protected phloridizin were tested. The bioactive was released in a controlled manner over several days. The formulation release profiles were reproducible suggesting that in principle the technology can be further developed to use in a commercial sense or for research purposes. The limitations of the technology, including formulation issues and gas diffusion through barrel walls, were identified.

Bibliography: leaves 210-223.

Thesis (Ph. D.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains xvii, 181 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 167-181).

Paper coatings or coating colours are high solidssuspensions that are applied to paper to improve chieflyprintability and optical properties. A paper coatingsuspension, including pigments, binders and thickeners, is acomplex system which must be understood if the end-useproperties of paper are to be improved. Some of the importantissues that need to be addressed are the mechanisms ofmigration of latices in a drying film, the influence ofthickener on the overall consolidation and the behaviour ofpaper coatings under compression.U nderstanding theconsolidation of paper coatings is essential as the aggregatestructures formed at this stage largely determine theperformance of the paper coating.Similarly, the forming ofpaper itself from pulp fibres requires a detailed understandingof the consolidation and dewatering process. In this thesis several approaches have been used in order tostudy the consolidation of paper coatings before and afterapplication to substrates. The techniques utilised arerheometry, centrifugation with NMR-imaging, scanning electronmicroscopy (SEM) and atomic force microscopy (AFM).Furthermore, investigations of the compressional rheology offibre systems has indicated that stepped pressure filtrationcan be a useful tool in the study of fibre dewatering. The primary findings presented in this thesis can besummarised as follows. Studies of the compressive yield stressand rheological properties of ground calcium carbonate (GCC)suspensions indicate that the addition of a commonly usedthickener can cause flocculation, most likely of a depletiontype, which leads to more compact structures during dewatering.When applied to substrates, migration and film formation ofbinder latices in the presence of calcium carbonate pigmentsand CMC thickeners occurs concurrently and collectively. Thisis shown to influence the consolidation of the top layer of thecoating to a great extent. It was found that CMC retards themigration of latices and that ethyl(hydroxyethyl)cellulose(EHEC) adsorbs to latex and creates a composite material uponlocal film formation. The composite retains an internalhoneycomb structure in the film, that is revealed by mapping ofelastic variations using AFM phase imaging. For fibre systems, the novel method of stepped pressurefiltration has been applied to study the compressional rheologyof pulp suspensions, and the effect of added surfactantsinvestigated. The technique is shown to be a promising tool forthe study of structure-dewatering relationships in fibresuspensions.

University of Macau / Faculty of Science and Technology / Department of Electromechanical Engineering

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