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Nepheline and Carnegieite Ceramics from A‐Type Zeolites by Microwave Heating
Author(s) -
Ohgushi Tatsuo,
Ishimaru Kazushi,
Komarneni Sridhar
Publication year - 2001
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.2001.tb00657.x
Subject(s) - nepheline , zeolite , materials science , crystallization , nepheline syenite , impurity , ceramic , microwave , microwave heating , mineralogy , chemical engineering , chemistry , metallurgy , organic chemistry , physics , catalysis , quantum mechanics , engineering
The thermal disintegration processes of A‐type zeolites and the properties of the materials that were formed after microwave heating (at 2.45 GHz) were studied. The thermal disintegration of 4A‐type zeolite proceeded as follows: disintegration at ∼880°C, followed by transformations to high‐carnegieite 1 at ∼920°C, nepheline (in nepheline(4A) form) at ∼990°C, and high‐carnegieite 2 at ∼1254°C (further heating led to melting at ∼1526°C). High‐carnegieite 1, nepheline(4A), and high‐carnegieite 2 efficiently absorbed microwaves. Cooling of the molten material yielded low‐carnegieite that contained some impurities. The change of 3A‐type zeolite proceeded as follows: disintegration at ∼910°C and transformation to nepheline (in nepheline(3A) form) at ∼1006°C. In 3A‐type zeolite, in contrast to 4A‐type zeolite, carnegieite did not form before the crystallization of nepheline(3A). Nepheline of high purity and carnegieite with some impurities were synthesized easily by heating 3A‐ and 4A‐type zeolites, respectively, using microwaves. These results suggest that the microwave heating of zeolites can be used to prepare some ceramic materials.