The objective of this master thesis was to investigate the possibility to measure the gain in stiffness of the dry coating due to film formation of latex with a Dynamic Mechanic Thermal Analyzer (DMTA). This could tell when and to which extent the latex forms a film after the drying process. Two latices with different Tg was used for the experiments, one with a Tg of 36°C, denoted hard, and the one with a Tg of 8°C, denoted soft. The hard latex was used to make coating samples that would not form a film when dried at room temperature and the soft latex was used as a reference to the coating with hard latex since it would form a film at room temperature. It was shown that a gain in stiffness due to film formation of latex in coating can be measured with a DMTA. It was also shown that that the film forming of latex in coatings depend on time, temperature and the history of the sample. Further investigations were carried out to try to determine the time for film formation to be completed at a certain temperature.. These investigations showed that this type of trials cannot be carried out in a DMTA directly since the stiffness seemed to increase monotonically during a very ling time. This might be due to the rearrangements in the pigment structure that might affect the gain in stiffness. Therefore, a method involving oven curing was developed. Only one series of test were performed with this method due to lack of time but the method showed promising results. / Syftet med detta examensarbete var att undersöka möjligheten att använda en Dynamic Mechanic Thermal Analyzer (DMTA) för att mäta ökningen av styvhet som följd av filmbildning av latex i en torr bestrykning. Två olika latexer användes för experimenten, en med Tg = 36°C (hård) och en med Tg = 8°C (mjuk). Den hårda latexen användes för att kunna göra tester på prover som ännu inte filmbildat när de torkat vid rumstemperatur och den mjuka latexen användes för att göra referens prover mot bestrykningen med hård latex. Resultaten visade att det går att mäta styvhetsökning i bestrykningen som en följd av filmformation med DMTA och filmformation av latex i bestrykningen troligtvis beror på både tid, temperatur och provets historia. Ett försök att mäta vilken uppehålls tid vid en specifik temperatur som krävs för att filmbildningen skall fulländas genomfördes. Dessa försök visade att DMTA:n inte var en lämplig metod för att mäta denna tid då styvheten verkade öka under en längre tid. Detta kan bero på att pigment partiklarna packade sig tätare och på så sätt orsakade en ökning av styvheten. Därför gjordes ett annat försök som involverar ugns härdning, men på grund av tidsbrist blev det bara en mätserie utförd. Den sist nämnda metoden visade dock goda resultat och måste därför bedömas ha en potential.

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The 7th German-Japanese Bridge Symposium, July 30-August 1, 2007 Osaka, JAPAN (GJBS07)

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The aim of the final prepared master work is to analyse technologies for painting of agricultural machinery, evaluate their influence on quality of coatings and offer quality improvement suggestions to agricultural machinery manufacturers. Quality of coatings of agricultural machinery is influenced by many factors, therefore resistance of coatings only to the main factors was investigated – water and abrasive particles. The results showed, that the most resistant for the impact of both factors are electrostatically applied coatings, in comparison with conventional and dip coatings. It was determined, that the water absorption by coatings process is described by polynomial equations, while the wear process mostly by power, linear and logarithmic as well. It was observed, that the thermodynamic parameters of the system, properties of coatings, number of layers and thickness, surface preparation method have the most significant influence on the water absorption level. Using the results of the research, one may evaluate and predict the influence of different painting technologies on quality and durability of coatings.

The objective of the investigation is to analyze effect of surface layer on mechanical properties of metal.

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No description available.

Microstructural comparison of the isothermal oxidation performance of an experimental Ni-5Cr-15Al overlay coating applied to CMSX-4 and CMSX-486 was performed at 1100 ℃. High temperature oxidation was carried out in a box furnace for a maximum duration of 192 hrs. Samples were periodically removed and the oxide, coating and substrates microstructurally analyzed using SEM, EDS and XRD equipment. Uncoated CMSX-4 and CMSX-486 were also oxidized using the same conditions in an attempt to understand how the coating affected oxidation performance based on microstructural changes. Results show that both CMSX-4 and CMSX-486 have unacceptable oxidation characteristics in the un-coated condition, where CMSX-486 had significantly better performance than CMSX-4. However, in the coated condition, both CMSX-4 and CMSX-486 had no significant difference in oxidation performance. It was found, in the un-coated and coated conditions, that the role of Hf in CMSX-486 played a significant role in determining oxidation performance of the material.

Each day, we are confronted with a large amount of more or less important information that we have to consider, and even in our digital society we need paper for communication, documentation and education. Much of the paper we use or are confronted by in our daily life, such as newspapers, books and packages, contains printed images or texts, and the appearance of both the print and the supporting surface is important. A good contrast between a printed text and the paper makes it easier to read, a detailed print of an illustration makes it more informative, and clear and evenly distributed colours on a package or on a poster make it more appealing. All of these qualities depend on the optical properties of the paper product and the the behavior of light illuminating the different materials. The aim of the work described in this thesis is to characterize the structure of coatings and prints, and to validate models for the optical response and interaction of ink and coating based on optical measurements of physical samples. It is the interactions between the printing ink and the porous structure of the coating layers that are subject to investigation. Experiments have been employed to relate the physical conditions in a flexographic printing nip to the ink setting, affected by the physical and chemical properties of the coating, to the resulting optical response of the printed paperboard. / The aim of the work described in this thesis is to characterize the structure of coatings and prints, and to validate models for the optical response and interaction of ink and coating based on optical measurements of physical samples. It is the interactions between the printing ink and the porous structure of the coating layers that are subject to investigation. Experiments have been employed to relate the physical conditions in a flexographic printing nip to the ink setting and the resulting optical response. By comparing simulated and measured results, it was shown that modifications of the surface properties account for the brightness decrease when substrates are calendered. Light scattering simulations, taking into account the surface micro-roughness and the increase in the effective refractive index, showed that surface modifications accounted for most of the observed brightness decrease, whereas the bulk light scattering and light absorption coefficients were not affected by calendering. Ink penetration affects the print density, mottling and dot gain. Results show that ink distribution is strongly affected by surface roughness, differences in pore size and pore size distribution. For samples having different latex amounts and different latex particle sizes, a higher print force did not increase the depth of penetrated ink to any great extent, but rather allowed the wetting to act more efficiently with a more evenly distributed ink film, a higher print density and fewer uncovered areas as a result. Uncovered areas could be linked both to local roughness variations and to local wettability variations on the surface. Samples with different ratios of calcium carbonate/kaolin clay pigment showed an increased porosity and an increase in print density with increasing amount of kaolin in the coating layer.