Effect of Eutectic Microstructure on the Properties of Ceramic Oxides.
Technical rept. 1 Feb 70-31 Jan 71,
UNITED AIRCRAFT CORP EAST HARTFORD CONN RESEARCH LABS
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Continued development of equipment and techniques to produce well-controlled, directionally solidified oxide eutectic ingots was undertaken. With eutectics exhibiting melting temperatures below approximately 1550C, bottom cooling of contained melts generally resulted in poorly controlled eutectic micro-structures due to the low liquid-solid thermal gradients caused by the thermal insulation of the growing ingot. Various floating-zone, directional solidification approaches were successfully developed which used resistance heaters surrounding andor in direct contact with the molten ceramic. At eutectic temperatures above approximately 1700C, apparent metal pick-up from the heaters was observed and radiant heating by refractory metal wires was found to be the best approach. The present emphasis is directed toward the growth of high temperature structural materials. Towards this end, a number of ingots of the Al2O3-ZrO2 eutectic containing Y2O3 as a stabilizer have been directionally solidified by the radiatively melted, floating-zone technique. Author
- Ceramics, Refractories and Glass