Simultaneous Synthesis and Consolidation of W-added ZrB₂ by Spark Plasma Sintering (SPS) and their Mechanical Properties

Abstract

Dense zirconium boride (ZrB₂)-based materials with and without tungsten (W) have been fabricated directly from mixtures of constituent elemental powders (Zr, B and W) by spark plasma sintering (SPS) at 1800°C for 10 min under 30 MPa in a vacuum. Formation processes of monolithic, W-doped ZrB₂ solid solutions ZrB₂ (ss) [(Zr_1-xW_x)B₂ (0<x≤0.12)], and composites consisting of ZrB₂ (ss) and WB₂ were investigated. Their mechanical properties of bending strength (σ_b), Vickers hardness (H_v) and fracture toughness (K_IC) at room temperature were evaluated. Solid solution and composite materials gave higher H_v (∼20 GPa), K_IC (∼4.4 MPam^1/2), and σ_b (∼600 and 690 MPa for the former and the latter, respectively) than those (14.1 GPa, 3.21 MPam^1/2, and ∼500 MPa) of the monolithic ZrB₂ ceramics fabricated under the same conditions.