Alkali attack on ceramic filters

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.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Materials Engineering

Department dc:contributor.department

Materials Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1990

Author dc:creator

• Vass, Raymond J.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-04142009-040442

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/42062