Accession Number : ADA564348


Title :   Testing and Modeling Ultra-High Temperature Ceramic (UHTC) Materials For Hypersonic Flight


Descriptive Note : Final rept. 1 Aug 2008-30 Nov 2011


Corporate Author : SRI INTERNATIONAL MENLO PARK CA MOLECULAR PHYSICS LAB


Personal Author(s) : Marschall, Jochen


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a564348.pdf


Report Date : 30 Nov 2011


Pagination or Media Count : 134


Abstract : This project focused on zirconium diboride and hafnium diboride ultra-high temperature ceramics in two main research areas: i) their thermal and electrical transport properties; and ii) their oxidation and volatilization behavior in simulated re-entry environments. The first area involved experimental studies of the thermal and electrical properties as a function of temperature, and the analysis of these results in terms of effective conductivity and Wiedemann-Franz models. Thermal diffusivity was measured using a photothermal radiometry technique, and the electrical resistivity and Hall coefficient were measured using a van der Pauw geometry. The second area involved experiments under simulated re-entry heating conditions at the 1.2 MW Plasmatron facility of the von Karman Institute for Fluid Dynamics in Rhode-Saint-Genese, Belgium. Zirconium diboride materials were tested over a range of surface temperatures exceeding 2000 C. A temperature-jump phenomenon was observed at threshold heating levels, at which the surface temperature spontaneously increased by hundreds of degrees under constant free-stream test conditions. This temperature jump is thought to be related to an abrupt transition in surface chemistry at the gas-surface interface. Both areas of research contribute to the continuing development of diboride-based materials for leading-edge applications on future hypersonic flight vehicles.


Descriptors :   *CERAMIC MATERIALS , *HYPERSONIC AIRCRAFT , ELECTRICAL PROPERTIES , HIGH TEMPERATURE , OXIDATION , REENTRY VEHICLES , SURFACE CHEMISTRY , SURFACE TEMPERATURE , THERMAL PROPERTIES


Subject Categories : Aircraft
      Ceramics, Refractories and Glass
      Unmanned Spacecraft
      Spacecraft Trajectories and Reentry


Distribution Statement : APPROVED FOR PUBLIC RELEASE