Effect of sintering temperature on the mechanical properties and microstructure of carbon nanotubes toughened TiB2 ceramics densified by spark plasma sintering

• Effect of CNTs addition on spark plasma sinterability of TiB2 ceramics was studied.
• Strength and toughness were enhanced to 741 MPa and 9.1 MPa m1/2, respectively.
• Toughening mechanisms were due to densification, crack deflection and CNTs pull-out.

TiB2-based composites containing 15 vol% multi-walled carbon nanotubes were synthetized at the temperature of 1600 °C to 1800 °C for 10 min under a uniaxial load of 20 MPa by spark plasma sintering. Microstructure, mechanical properties and densification behavior of the composites were studied. It was shown that mechanical properties were increased by introduction of carbon nanotubes, especially for the fracture toughness. The fracture toughness was ∼9.1 MPa m1/2, which was much higher than that of monolithic TiB2 ceramics. The dense microstructure was the primary factor to improve the mechanical properties. The toughening mechanisms were crack deflection and carbon nanotubes pull-out. The results presented here provide a potential method for improving the fracture toughness of TiB2 ceramics.