Ultrahigh-Temperature TaB2 Based Composite Materials Sintered by Different Methods

Sintering processes were studied for TaB2 and its mixtures with 20 and 30 wt % of SiC, ZrSi2, and MoSi2 under hot pressing (HotP) and high pressure–high temperature (HPHT) conditions and TaB2 and its mixtures with 20 and 30 wt % of SiC under spark plasma sintering (SPS) conditions. The introduction of additives led to the formation of solid solutions on the basis of TaB2 and SiC and new phases. For TaB2, the Vickers hardness was НV(9.8 N) = 32.4 GPa after HotP and НV(49 N) = 20.8 GPa after SPS (1950°C, 0.05 h), and the fracture toughness was KIc (49 N) = 7.6 MPa m0.5. The Young modulus was essentially improved from 532 to 853 GPa by adding 20 wt % of SiC after HotP. Sintering TaB2 mixtures with 30 wt % of SiC resulted in the materials with НV(9.8 N) = 39.4 GPa, KIc(9.8 N) = 6.75 MPa m0.5(HPHT) and НV(49 N) = 25.4 GPa, KIc(49 N) = 10.8 MPa m0.5(SPS).