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Name: Zirconium Diboride (ZrB2/SiC)
Database: NASA Ames Thermal Protection Materials
Category: Ultra-High Temperature Ceramics
Composition: Zirconium Diboride(ZrB2) with 20 volume percent of a Silicon Carbide (SiC) particulate phase.
Manufacturer: There are no current commercial manufacturers of the UHTC materials.
Technical Readiness Level: 3
Last Modified: 2001-10-01

Description:

• These UHTC materials were fabricated by uniaxial hot pressing powder mixtures of ZrB2 and SiC. After mixing the powders were loaded into graphite dies for hot pressing. The dies were lined with pyrolytic graphite paper that was coated with a boron nitride wash. Hot pressing was conducted in an inert atmosphere at temperatures between 1800¡C and 2200¡C and pressures between 2500 to 4000 psi for 1 to 5 hours. The resulting composites attained greater than 98% of theoretical density with an average grain size of ~8 mm. The material properties are relatively isotropic with no significant orientation dependence induced by the uniaxial hot pressing. Studies have indicated that the SiC improves the oxidation resistance of the composite compared to that of pure ZrB2. The UHTC materials are have sufficient electrical conductivity to allow components to be machined by EDM. Currently NASA Ames Research Center has active programs on the processing, characterization and development of these materials for TPS applications, such as sharp leading edges on next generation reusable launch vehicles. <BR><BR> All UHTC material property data are from samples produced by MANLABS, INC. under contract to the air force and published in a series of technical reports (AFML-TR-68-190).

Point of Contact:

• Donald T. Ellerby
• NASA Ames Research Center
• dellerby@mail.arc.nasa.gov