NSF Award
9460515
This Small Business Innovation Research Phase I project describes a novel processing route to develop an improved, thermal shock resistant, high strength glass-ceramic composed essentially of pollucite (CsAlSi2O6) crystals. Crystalline pollucite has excellent refractoriness (melts above 1900ÝC), a low coefficient of thermal expansion, high mechanical strength and good chemical durability. Previous attempts to prepare essentially pollucite-based glass-ceramics have been largely unsuccessful due to high melting temperatures, significant volatilization of cesium at temperatures above 1800ÝC, and the unavailability of a suitable container to hold these high temperature melts. A nonconventional method, which uses pollucite glass microspheres (beads) as precursors, followed by hot-pressing and crystallization, will be used to fabricate glass-ceramics in the present investigation. The precursor glass beads will be prepared by a flame spraying method (>2500ÝC), which avoids the volatilization of cesium that occurred in all previous attempts to make pollucite glass-ceramics. A few selected properties which establish the suitability of a material for practical use, such as the thermal expansion coefficient, chemical durability, and flexural strength will also be measured for these glass-ceramics.
