ZrB(2)-CNTs Nanocomposites Fabricated by Spark Plasma Sintering

ZrB(2)-based nanocomposites with and without carbon nanotubes (CNTs) as reinforcement were prepared at 1600 °C by spark plasma sintering. The effects of CNTs on the microstructure and mechanical properties of nano-ZrB(2) matrix composites were studied. The results indicated that adding CNTs can inhibit the abnormal grain growth of ZrB(2) grains and improve the fracture toughness of the composites. The toughness mechanisms were crack deflection, crack bridging, debonding, and pull-out of CNTs. The experimental results of the nanograined ZrB(2)-CNTs composites were compared with those of the micro-grained ZrB(2)-CNTs composites. Due to the small size and surface effects, the nanograined ZrB(2)-CNTs composites exhibited stronger mechanical properties: the hardness, flexural strength and fracture toughness were 18.7 ± 0.2 GPa, 1016 ± 75 MPa, and 8.5 ± 0.4 MPa·m(1/2), respectively.