Reference

Preferential crystallization of cristobalite and mullite from Egyptian bentonite

Preferential crystallization of cristobalite and mullite from Egyptian bentonite. El-Hiti, A. S. (Phys. Dep., King Saud Univ., Riyadh, Saudi Arabia). J. Coll. Sci., King Saud Univ., 15(2), 557-64 (English) 1984. CODEN: JCSUDU. DOCUMENT TYPE: Journal CA Section: 53 (Mineralogical and Geological Chemistry) The bentonite studied was obtained from Fayoum (Egypt) and is composed of a monotmorillonite mineral (67.2) and quartz (32.8%). As pressure is applied to the bentonite, flaky particles tend to lie with their planes parallel to the pressure. The X-ray diffractometer was used to follow the preferred orientation and the anisotropy of green bodies of bentonite after firing at 1100 and 1200°. The structural anisotropy factor for the (101) plane of cristobalite [14464-46-1] and the (210) plane of mullite [1302-93-8] was evaluated. Results showed that the flaky nature of bentonite particles and its layer structure are responsible for the anisotropy obsd. in the fired discs prepd. from raw bentonite by pressure.

High-temperature phases in muscovite and talc-containing organosilicate compositions

High-temperature phases in muscovite and talc-containing organosilicate compositions. Krotikov, V. A.; Bessonov, A. A.; Kharitonov, N. P. (USSR). Kremniiorg. Soedin. Mater. Ikh Osn., Tr. Soveshch. Khim. Prakt. Primen. Kremniiorg. Soedin., 5th, Meeting Date 1981, 167-9. Edited by: Reikhsfel'd, V. O. Nauka, Leningr. Otd.: Leningrad, USSR. (Russian) 1984. CODEN: 52OZAK. DOCUMENT TYPE: Conference CA Section: 37 (Plastics Manufacture and Processing) Section cross-reference(s): 57 Formation of new cryst. phases was obsd. in heat-resistant compns. contg. muscovite [1318-94-1] and/or talc [14807-96-6], di-Me siloxane-Ph silsesquioxane (I), and, in some cases, Cr2O3 or TiO2 during heating in air at ￡1300°. For example, a compn. consisting of muscovite and I showed no new phases at ￡900°, showed a spinel (MgAl2O4) [1302-67-6] phase at 1000°, a mullite [1302-93-8] phase at 1100-1300°, and the a-form of cristobalite [14464-46-1] at 1200°.