Non-contact measurement of creep resistance of ultra-high-temperature materials

Continuing pressures for higher performance and efficiency in energy conversion and propulsion systems are driving ever more demanding needs for new materials which can survive high stresses at the elevated temperatures. In such severe environments, the characterization of creep properties becomes indispensable. Conventional techniques for the measurement of creep are limited to about 1700 °C. A new method which can be applied at temperatures higher than 2000 °C is strongly demanded. This paper presents a non-contact method for creep measurements of ultra-high-temperature materials at 2300 °C. Using the electrostatic levitation facility at NASA MSFC, a spherical sample was rotated quickly enough to cause creep deformation due to centripetal acceleration. The deformation of the sample was captured with a digital camera, and the images were analyzed to measure creep deformation. To validate experimental results, numerical and analytical analyses on creep deformation of a rotating sphere have been conducted. The experimental, numerical, and analytical results showed good agreement with one another.