Simultaneous Synthesis and Consolidation of W-Added ZrB2 by Pulsed Electric Current Pressure Sintering and their Mechanical Properties
Dense zirconium boride (ZrB2)-based materials with and without tungsten (W) have been fabricated directly from mixtures of constituent elemental powders by pulsed electric current pressure sintering (PECPS) at 1800°C for 10 min under 30 MPa in a vacuum. Formation processes of monolithic, W-doped ZrB2 solid solutions (Zr1-xWx)B2 (0<x≤0.12), and composites consisting of ZrB2(ss) and WB2 were investigated. Their mechanical properties of Vickers hardness (Hv), fracture toughness (KIC), and bending strength (σb) at room temperature were evaluated. Solid solution and composite materials gave higher Hv (~20.7 GPa), KIC (∼4.4 MPam1/2), and σb (~600 and 690 MPa for the former and the latter, respectively) than those (14.1 GPa, 3.21 MPam1/2, and ~500 MPa) of the monolithic ZrB2 fabricated under the same conditions. Furthermore, the latter two materials exhibited excellent high-temperature σb values (~550-600 MPa) up to 1600°C in N2, in comparison with that (~320 MPa) of monolithic ZrB2 materials.