| 摘要 |
This invention relates to processes for preparing ceramic articles which are especially suited for electronic applications. The process involves taking a shaped article which has been formed from a magnesium exchanged zeolite powder, the zeolite selected from the group consisting of philipsite, harmotome, gismondine, zeolite B, zeolite ZK-19 and zeolite W, and sintering it at a temperature of about 1,000 DEG C. to 1,350 DEG C. for about 1 to about 6 hours. The magnesium exchanged zeolite has a SiO2/Al2O3 ratio of about 2.3 to about 2.8 and a sodium content less than 0.5 weight percent. The ceramic article that is formed has a substantially crystalline cordierite phase and has a density of at least 90% of its theoretical density. A preferred process involves calcining the magnesium exchanged zeolite powder at a temperature of about 600 DEG -800 DEG C. to collapse the zeolite framework and give upon sintering a cordierite ceramic article which is substantially crack free. A preferred magnesium exchanged zeolite is magnesium exchanged zeolite B. This invention also relates to a substantially crack free and crystalline cordierite ceramic article, the cordierite represented by the empirical formula 2.0+/-0.1 MgO:2 Al 2O3:5.0+/-0.2 SiO2 and has an average grain size of about 10 to about 500 nanometers.
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