No description available.

No description available.

No description available.

No description available.

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.

The polymer-clay nanocomposites, when applied as coating materials, are expected to improve the barrier properties without sacrificing mechanical and thermal properties, and thus solve one of the most challenging problems existing in current food and beverage packaging using paper barrier coating. Furthermore, a stable polymer composite suspension in an aqueous form has many other advantages such as better environmental concern, easier manipulation and better energy saving. However, the research in this area is quite limited in the literature. In this research, a stable water-based suspension of polymer-encapsulated nanoclay composite has been successfully synthesized. The polymer nanocomposites, which encapsulate the exfoliated and well-dispersed nanoclay inside the polymer matrix, can dramatically improve almost all the aspects of mechanical properties and thermal stability in comparison with that of pure polystyrene (PS) and polystyrene butyl acrylate (PSBA) films. The particle size of nanoclay and the surface modification method are two important factors for emulsion stability, the encapsulation and intercalation (or exfoliated) degree of nanoclay. Furthermore, the impact of nanoclay on miniemulsion kinetics has been extensively investigated and the results show the hindrance of nanoclay on styrene miniemulsion polymerization kinetics.

Prepainted metal sheets being environment friendly and cost effective as compared to postpainted metal sheets, are widely used in construction, packaging, transportation and automotive industries. One of the key requirements for prepainted coatings is to retain its surface quality and properties during forming process. During forming process, major surface damage occurs when the coated sheet is bent and un-bent around the die corner. To reduce surface damage of coatings, proper control of the parameters during forming and detail study of the surface conditions is required. In the present study, influence of forming parameters such as die radius, lubrication and specimen material are investigated. The influence of these parameters on friction, surface damage and properties of polymer coatings are evaluated. Experiment set-up is built to conduct bending under tension test. This test gives a better way to evaluate coating performance, as it closely simulates the die region of real forming process and considers bending effects. Experimental results show increase in friction and surface damage with decrease in die radius. Moreover, with decrease in die radius hardness of the coating decreases and strain in the specimen increases. Lubrication has some effect on coefficient of friction, but the influence is not as significant as that of die radius. This is attributed to the fact that, the polymer coating itself acts as a solid lubricant in the test. Material effect was studied, polypropylene coating being the softer material compared to PVDF coating shows more surface damage in the form of scratches. Numerical simulations were performed using Finite Element Analysis package (FEA) Abaqus. A 2D model was built, exploiting the plane strain condition for bending under tension test. Numerical simulations indicate that maximum contact pressure and von Mises stress are concentrated at the beginning of the drawing edge. Apart from the location, the value of contact pressure was higher for smaller die radius. Thus, experiments help in studying the effect of forming parameters on coating performance and numerical simulations provide more insight into the critical areas where stresses are high. Numerical simulations also provide a scope to study the effect of material and geometric parameters on performance of coatings without running experiments.

<p>This work describes how a fatty acid methyl ester (FAME) derived from a vegetable oil can be introduced as reactive diluent in a solvent-borne thermally cured coil-coating system. The evaluated reactive diluent, rape seed methyl ester (RME), has been evaluated both in a fully formulated clear coat system and via model studies.</p><p>A reactive diluent is a compound that acts as a solvent in the liquid paint, lowering the viscosity, and chemically reacts into the final film during cure. Introduction of a reactive diluent derived from vegetable oil give a more environmental compliant coating since a renewable material is incorporated in the coating and the amount of traditional solvent can be decreased. These positive environmental factors have increased the industrial interest.</p><p>The fully formulated clear coat studies describes how addition of reactive diluent affects rheological properties of the wet paint, film formation, incorporation, and final film properties in a hydroxyl-functional polyester/melamine coil-coating system. The coating were cured under industrial coil-coating cure conditions and analyzed with Raman, carbon-14 dating, extraction, dynamic mechanical analysis, and visually observed. Viscosity measurement of the wet paint show that RME works as a diluent. RME increase the mobility in the system enhancing the film formation process and occurrence of defect-free films. The incorporation of RME could not be confirmed by Raman analysis. However, carbon-14 dating did indicate the presence of RME that could not be extracted from the films. The appearance and mechanical properties of the films were also significantly affected by addition of RME. Dynamic mechanical analysis of the free standing films showed that the final film properties were affected by oven temperature, choice of co-solvent, and flash-off period.</p><p>Model studies were performed to further clarify how RME chemically can react through transesterification with the hydroxyl-groups of the polyester. RME and its two main components methyl oleate and methyl linoleate were reacted with primary alcohols with and without tertiary hydrogen both under low temperature (110, 130, 150, 170°C) and industrial cure conditions. The transesterification reaction was monitored with 1H-NMR and real time IR. Evaporation and side reactions, e.g. oxidation, are competing factors with the transesterification reaction. The fatty acid structure affects the conversion as a higher amount of unsaturations triggers higher degree of oxidation. The study also showed that reaction time and temperature affects the transesterification conversion, degree of side reactions, and catalyst choice.</p>

Title from PDF of title page. / Document formatted into pages; contains 78 pages. / Thesis (M.S.M.E.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: This thesis focuses on identifying hard material pairs with low roughness, high coefficient of static friction, high wear resistance and high modulus of elasticity, suitable for sliding in dry friction conditions under a normal load. A wide range of materials including various steels, various coatings on tool steels deposited by various deposition techniques and different ceramics were examined and considered for tribological testing. Procedures and sequences were developed for conducting tribology tests on the material pairs. High endurance - low cycle tests were conducted and based on the performance of material pairs with respect to friction, wear and surface roughness a small set of material pairs and coatings was selected for further testing. High endurance - high cycle tests were performed on an additional seventeen pairs of material pairs selected for long term sliding. / ABSTRACT: Material pairs were selected for low endurance tests based on high corrosion resistance along with all the above specified design parameters. Low endurance tests were conducted to identify material pairs sliding for a short distance in humid environments. Results are tabulated and pictures of the material pairs after wear tests are presented. It was found that four material pairs for high endurance applications and two pairs for the low endurance applications performed very well in regard of design specifications. These material pairs find a major application in friction clamps of an Inchworm motor resulting in enhancement of force output of the motor. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 166-173). Available also in a digital version from Dissertation Abstracts.