Evaluation of Tantalum Fiber Reinforced Si3N4.
Final rept. 1 Mar 76-1 Mar 77,
UNITED TECHNOLOGIES RESEARCH CENTER EAST HARTFORD CONN
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Ceramic materials, by virtue of their high melting points and oxidation resistance, can offer large gains in gas turbine performance, provided some serious limitations can be overcome. These are poor thermal shock resistance and, more critically, low impact strength. Hot-pressed silicon nitride, currently the leading candidate for use as a high temperature vane material, has not only good oxidation resistance but also very good thermal shock resistance for a ceramic material. However, its use is still limited by its relatively low impact strength. It is the solution of this problem that UTRC has emphasized in the current contract with NADC on improving the impact strength of Si3N4 through the use of fiber or wire reinforcements. This approach provides energy absorption modes not available in monolithic materials. By tailoring the properties of the composite it is possible not only to maximize energy absorption during impact but to control the type of fracture as well. Small fragments breaking out of vanes are probably tolerable under abnormal impact loads whereas total failure is unacceptable. Author
- Ceramics, Refractories and Glass
- Laminates and Composite Materials
- Metallurgy and Metallography