Nepheline and carnegieite ceramics from A-type zeolites by microwave heating

The thermal disintegration processes of A-type zeolites and the properties of the materials that were formed after microwave heating (at 2.45 GHz) wer e studied, The thermal disintegration of 4A-type zeolite proceeded as follo ws: disintegration at similar to 880 degreesC, followed by transformations to high-carnegieite 1 at similar to 920 degreesC, nepheline (in nepheline(4 A) form) at similar to 990 degreesC, and high-carnegieite 2 at similar to 1 254 degreesC (further heating led to melting at similar to 1526 degreesC). High-carnegieite 1, nepheline(4A), and high-carnegieite 2 efficiently absor bed microwaves, Cooling of the molten material yielded low-carnegieite that contained some impurities. The change of 3A-type zeolite proceeded as foll ows: disintegration at similar to 910 degreesC and transformation to nephel ine (in nepheline(3A) form) at similar to 1006 degreesC. In 3A-type zeolite , in contrast to 4A-type zeolite, carnegieite did not form before the cryst allization of nepheline(3A), Nepheline of high purity and carnegieite,with some impurities mere synthesized easily by heating 3A- and 3A-type zeolites , respectively, using microwaves, These results suggest that the microwave heating of zeolites can be used to prepare some ceramic materials.