Development of Directionally Solidified Eutectic Ceramic Matrix-Metal Composites
Final rept. Apr 1976-Apr 1977
UNITED TECHNOLOGIES RESEARCH CENTER EAST HARTFORD CT
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The third and final year of effort to identify and develop directionally solidified ceramic matrix-metal eutectic composites for use uncoated at temperatures exceeding 1315 C 2400 F in aircraft gas turbines is reported. The primary approach was to identify oxide-metal systems in which the metal whisker phase would form a self-protective oxide coating on exposure to air at elevated temperatures. Many different oxide-metal combinations were examined by melting prefired slugs contained tungsten wire baskets. The specimens were melted by radiation from a carbon susceptor inductively heated in argon. A wide range of cubic mixed oxides in combination with high-melting pure metal candidates were examined. A number of compositions were found which solidified as regular oxide-metal eutectics but difficulties with container reactivities and with the volatility of certain components prevented the fabrication of ingot samples suitable for further evaluation. Although the possibility remains that suitable eutectic systems may exist, the general conclusion from this work is that chances for the successful development of an oxide-metal eutectic system for structural use uncoated in air at elevated temperatures should now be considerably reduced.
- Laminates and Composite Materials