| 摘要 |
Substantially crack free ceramic articles having less than 5% porosity are prepared by starting with a potassium or cesium or rubidium exchanged zeolite or mixtures thereof, the zeolite characterized in that it has a SiO2/AI2O3 ratio of 3.5 to 7.5, and calcining it at a temperature of 900.degree. to 1100.degree.C for a time sufficient to collapse the zeolite framework and provide an amorphous powder. Next, the amorphous powder is formed into a shaped article and the article is sintered at a temperature of 1150.degree. to 1400.degree.C for a time of 0.5 to 12 hours to give a ceramic article whose principal crystalline phase is tetragonal leucite when potassium exchanged zeolite is used, or when the zeolite is exchanged with cesium, a ceramic article whose principal crystalline phase is pollucite is obtained, or when a rubidium exchanged zeolite is used a ceramic article whose principal crystalline phase is rubidium leucite is obtained, and when a potassium/cesium exchanged zeolite is used a ceramic article having as its principal crystalline phase a leucite/pollucite solid solution is obtained. The addition of pollucite to the leucite article provides a ceramic article whose thermal expansion coefficient can be varied from 2 x 10-6 to 27 x 10-6.degree.C-1 as measured over the range 50.degree.-700.degree.C. This invention also relates to this leucite/pollucite ceramic article.
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