Fabrication of SPS Compacts from Ta, Hf-Containing ZrB2-ZrC Powder Mixtures Synthesized by the MA-SHS in Air Process
Mechanical Activation assisted Self-propagating High-temperature Synthesis in air (MA-SHS in air process) was successfully applied to the synthesis of the powder mixtures of ZrB2 and ZrC containing Ta and Hf as a precursor of Ultra High Temperature Ceramic (UHTC) matrix composites. When the powder mixtures of (Ta or Hf+Zr)/B/C=2/2/1 (Ta or Hf/Zr=0/2, 0.1/1.9, 0.2/1.8, 0.4/1.6) in molar ratio were mechanically activated (MA) by ball milling for 45-60 min and then exposed to air, they self-ignited spontaneously and the self-propagating high-temperature synthesis (SHS) was occurred to form ZrB2 and ZrC. From these MA-SHS powders, the Ta, Hf-containing ZrB2-ZrC composite compacts having a fine and homogeneous microstructure composed of < 5 μm-sized grains were fabricated by spark plasma sintering (SPS) at 1800°C. The mechanical properties of the composites evaluated by Vickers indentation method was improved by the addition of Ta and showed the values of Vickers hardness (HV) of 16.9 GPa and fracture toughness of 4.3 MPa·m1/2.
T. Tsuchida and K. Mochizuki, "Fabrication of SPS Compacts from Ta, Hf-Containing ZrB2-ZrC Powder Mixtures Synthesized by the MA-SHS in Air Process", Advances in Science and Technology, Vol. 45, pp. 1041-1046, 2006