Synthesis and Processing of Ultra-High Temperature Metal Carbide and Metal Diboride Nanocomposite Materials
Abstract
Zirconium diboride and a zirconium diboride/tantalum diboride mixture were synthesized by solution-based processing. Zirconium n-propoxide was refluxed with 2,4-pentanedione to form zirconium diketonate. This compound hydrolyzed in a controllable fashion to form a zirconia precursor. Spherical particles of 200-600 nm for pure ZrB2 and ZrB2-TaB2 mixtures were formed. Commercial powders of ZrB2 containing various concentrations of B4C, SiC, TaB2, and TaSi2 were pressureless-sintered and post-HIPed to their theoretical densities. Oxidation resistances were studied by scanning thermogravimetry over the range 1150-1550 deg C. SiC additions improved oxidation resistance over a broadening range of temperatures with increasing SiC content. Tantalum additions to ZrB2-B4C-SiC in the form of TaB2 and/or TaSi2 increased oxidation resistance over the entire evaluated spectrum of temperatures. TaSi2 proved to be a more effective additive than TaB2. Silicon-containing compositions formed a glassy surface layer, covering an interior oxide layer. This interior layer was less porous in tantalum-containing compositions.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 15, 2008
- Accession Number
- ADA483979
Entities
People
- Robert F. Speyer
Organizations
- Georgia Tech