Self-Propagating High-Temperature Synthesis (SHS) and Spark Plasma Sintering (SPS) of Zr-, Hf-, and Ta-Based Ultra-High Temperature Ceramics

Abstract

The identification of efficient techniques for the fabrication of Ultra High Temperature Ceramics (UHTCs) is very crucial in view of their rapid and wider development. Along these lines, the use of the self-propagating high-temperature synthesis (SHS) technique in combination with the SPS technology is examined in this chapter for the obtainment of fully dense MB2-SiC and MB2-MC-SiC (M=Zr, Hf, Ta) ceramics. The starting reactants are first processed by SHS to successfully form the desired composites. The resulting powders are subsequently consolidated by spark-plasma sintering (SPS). Bulk products with relative densities = 96% can be obtained within 30 minutes, when the dwell temperature is 1800 °C and P=20 MPa. Hardness, fracture toughness, and oxidation resistance of the obtained dense bodies are comparable to, and in some cases superior than, those reported for analogous products synthesized using alternative routes. Possible future developments of this approach with the final purpose of obtaining whiskers/fibers reinforced UHTCs are finally discussed.