Jonghyun Lee

Contact: jhyunlee@acad.umass.edu

        Continuing pressures for higher performance and efficiency in propulsion are driving ever more demanding needs for high-temperature materials.  The combination of high stresses and high temperatures may result in creep-induced system failure.  The characterization of creep properties is very important where long service life at high-temperatures and high stress is anticipated, such as in combustion chambers for advanced chemical rockets and turbomachinery for jet engines and power conversion in nuclear-electric/nuclear thermal propulsion. 

        Some very high-temperature materials are being developed, including platinum group metals, carbides, nitrides and silicides.  But the measurement of creep properties at very high temperatures is itself difficult, because the testing instrument must operate at such high temperatures.  Test materials often become reactive at high temperature and may react with the test container, impairing test results.  Conventional methods are limited to temperatures below ~1,700.

            The objective is to develop, validate and utilize an ESL (Electrostatic Levitation)-based method for the measurement of creep in materials at high temperature (~2,500 ºC). The research is being conducted by analytical, numerical, and experimental analyses. This project is being supported by NASA MSFC, Huntsville, AL.

von Mises stress distribution of Nb sphere