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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the 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.
1

Alkali attack on ceramic filters

Vass, Raymond J. 14 April 2009 (has links)
Experiments were performed to determine a suitable binder material for silicon carbide-based ceramic filter. These experiments included exposure of 42% and 60% alumina, aluminosilicates to potassium and sodium containing environments for the purpose of determining the phases that would form and to determine concentration profiles. In addition, thermodynamic calculations were performed to predict the phases that would form when the alkali reacted with the aluminosilicate. The results of the thermodynamic calculations indicated that the alkali compounds will react at temperatures as low as 800°C. The exposure experiments verified this result. The phases that formed during the sodium vapor exposures and confirmed the thermodynamic calculations and were as follows: 1. sodium metasilicate and a solid solution of sodium aluminum silicates and carnegieite and for potassium vapor exposure. 2. potassium disilicate, kaliophilite-nepheline, potassium aluminate, and 5K₂O-5Al₂O₃-8SiO₂. Experiments also revealed that penetration depth by alkali compounds was restricted to a region near the surface of the material when the combination of temperature and sodium concentration alowed a melt to form. The results also indicated that the 42% alumina, aluminosilicate had superior resistance to alkali attack than the 60% alumina, aluminosilicate at temperatures below 1225°C. / Master of Science

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