Scalable, Solution-Phase Routes Towards Metal Carbides
Technical Report,30 Sep 2015,29 Sep 2019
OHIO STATE UNIVERSITY Columbus United States
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The overall goal of our AFOSR program is to establish a scalable, solution-phase routes for the synthesis of amorphous, crystalline, and nanoparticle early transition metal carbides, as well as ternary transition metal carbides. These materials occupy a unique niche in the aerospace industry, particularly for high-temperature applications due to the fact that they are incredibly refractory, chemically robust and electronically conducting ceramic materials. However, the traditional way of synthesizing carbide materials requires ultra-high temperatures 1000 C, on account of the slow diffusion constants of carbon through most materials. The need for high temperatures are not only resource intensive and costly, but make it virtually impossible to control the morphology, lead to graphitic side products, and limit the achievable phases to those with high thermodynamic stability. Our central hypothesis is that a solution-phase route for synthesizing a broad class of metal carbide materials can be uniquely enabled via the transmetalation of molecular C4- precursors that contain 4 C-B bonds withmetalhalogen M-X bond containing precursors to form M-C bonds. During this last cycle we established that the nitrogen-containing C4- precursor tetrakis1,3-propanediaminoborylmethane i.e. CBpn4 can serve as an ideal carbon source for the low temperature sol-gel synthesis of transition metal carbides. The solvothermal reaction between this compound and TiBr4 at 210 C enabled the formation of an amorphous branched Ti-C polymer that had a mass loss and TiBr ratio indicative of 3 C-Ti bonds. Annealing this tri-substituted product above 300 C resulted in complete substitution and elimination of residual boryl groups and the formation of an amorphous TiC product.
- Inorganic Chemistry
- Physical Chemistry