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High-precision Non-Contact Measurement of Creep of Ultra-High Temperature Materials for AerospaceFor high-temperature applications (greater than 2,000 C) such as solid rocket motors, hypersonic aircraft, nuclear electric/thermal propulsion for spacecraft, and more efficient jet engines, creep becomes one of the most important design factors to be considered. Conventional creep-testing methods, where the specimen and test apparatus are in contact with each other, are limited to temperatures approximately 1,700 C. Development of alloys for higher-temperature applications is limited by the availability of testing methods at temperatures above 2000 C. Development of alloys for applications requiring a long service life at temperatures as low as 1500 C, such as the next generation of jet turbine superalloys, is limited by the difficulty of accelerated testing at temperatures above 1700 C. For these reasons, a new, non-contact creep-measurement technique is needed for higher temperature applications. A new non-contact method for creep measurements of ultra-high-temperature metals and ceramics has been developed and validated. Using the electrostatic levitation (ESL) facility at NASA Marshall Space Flight Center, a spherical sample is rotated quickly enough to cause creep deformation due to centrifugal acceleration. Very accurate measurement of the deformed shape through digital image analysis allows the stress exponent n to be determined very precisely from a single test, rather than from numerous conventional tests. Validation tests on single-crystal niobium spheres showed excellent agreement with conventional tests at 1985 C; however the non-contact method provides much greater precision while using only about 40 milligrams of material. This method is being applied to materials including metals and ceramics for non-eroding throats in solid rockets and next-generation superalloys for turbine engines. Recent advances in the method and the current state of these new measurements will be presented.
Document ID
20080032812
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Rogers, Jan R.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Hyers, Robert
(Massachusetts Univ. United States)
Date Acquired
August 24, 2013
Publication Date
June 23, 2008
Subject Category
Metals And Metallic Materials
Meeting Information
Meeting: 2008 National Space and Missile Materials Symposium,
Location: Nevada
Country: United States
Start Date: June 23, 2008
End Date: June 27, 2008
Sponsors: General Dynamics Information Technology
Distribution Limits
Public
Copyright
Other

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