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The Global ETD Search service is a free service for researchers
to find electronic theses and dissertations. This service is
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Networked Digital Library of Theses and Dissertations.
Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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Functionalization of carbon-bonded ceramic foam filters with nano-scaled materials for steel melt filtrationStorti, Enrico 23 April 2018 (has links) (PDF)
In order to improve the purity of steel castings, the use of special reactive coatings on carbon-bonded ceramic foam filters was explored. Carbon nanotubes were dispersed in water by means of ultrasonic treatment, using xanthan gum to stabilize the nanotubes in suspension and control the rheological behavior. The coatings were applied by cold spraying and binding was achieved during heat treatment in reducing atmosphere, thanks to an artificial pitch added to the slurry. The coated filters were successfully immersed in molten steel for different times. The thickness of the first alumina layer generated at the interface was independent of the immersion time: concentration gradients through its thickness suggested that the formation of this structure is limited by diffusion. Investigation of the steel after solidification by means of ASPEX showed that the presence of the coating influenced the size as well as the chemical composition of the remaining inclusions. Nano-coated filters had the best filtration efficiency (up to 95% for alumina inclusions after 10 s), but longer tests resulted in worse performance. In addition, coatings based on calcium aluminates in combination with carbon showed an efficiency greater than 97% for steel samples taken directly from the melt.
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Functionalization of carbon-bonded ceramic foam filters with nano-scaled materials for steel melt filtrationStorti, Enrico 23 March 2018 (has links)
In order to improve the purity of steel castings, the use of special reactive coatings on carbon-bonded ceramic foam filters was explored. Carbon nanotubes were dispersed in water by means of ultrasonic treatment, using xanthan gum to stabilize the nanotubes in suspension and control the rheological behavior. The coatings were applied by cold spraying and binding was achieved during heat treatment in reducing atmosphere, thanks to an artificial pitch added to the slurry. The coated filters were successfully immersed in molten steel for different times. The thickness of the first alumina layer generated at the interface was independent of the immersion time: concentration gradients through its thickness suggested that the formation of this structure is limited by diffusion. Investigation of the steel after solidification by means of ASPEX showed that the presence of the coating influenced the size as well as the chemical composition of the remaining inclusions. Nano-coated filters had the best filtration efficiency (up to 95% for alumina inclusions after 10 s), but longer tests resulted in worse performance. In addition, coatings based on calcium aluminates in combination with carbon showed an efficiency greater than 97% for steel samples taken directly from the melt.
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