Directionally Solidified In-Situ Eutectic Ceramic Matrix-Metal Composites.
Abstract
The objective of this work was to identify and develop directionally solidified ceramic matrix-metal eutectic composites for use uncoated at temperatures of 2400 F and preferably higher in aircraft gas turbines. The primary approach was to discover metal-oxygen systems in which the metal whisker phase would form a self-protective oxide coating on exposure to elevated temperatures. Many different metal-oxygen combinations were melted and examined mostly using prefired slugs held in tungsten wire baskets which were heated by radiation inside a carbon susceptor in argon. Practically all compositions could be directionally solidified successfully inside CVD tungsten tubes partially sealed at their ends. Additives which provided additional oxygen to the melt such as CeO2, Cr2O3 and WO3 were often necessary to increase the metal solubility sufficiently to form a eutectic microstructure. A number of potentially interesting systems, Gd2O3-CeO2-Ta, Y2O3-CeO2-Ta, and Y2O3-CeO2-Y, could not survive a 24 hr exposure to air at 2000 F. The Cr-Al2O3, Cr2O3 system, however, showed a surface attack of only a few mils after an exposure of 60 hrs in air at 2600 F. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 15, 1975
- Accession Number
- ADA013602
Entities
People
- Charles O. Hulse
Organizations
- United Technologies Corporation