Investigation of AlN addition on the microstructure and mechanical properties of TiB2 ceramics

Abstract TiB 2 ceramics with AlN addition were hot pressed at the temperature of 1800 °C under a load of 30 MPa for 1 h to investigate the effect of AlN particles addition as a sintering aid on the densification, mechanical properties, and microstructure of TiB 2 . AlN addition improved the densification behavior of TiB 2 , and for TiB 2 containing 10 wt% (13.35 vol%) AlN, the relative density of 97.5% was achieved. Mechanical properties of composites including Vickers hardness, flexural strength, and fracture toughness was measured. The Vickers hardness of 27.31 GPa was obtained for TiB 2 - 2.5 wt% AlN. SEM micrographs and XRD patterns of hot pressed ceramics revealed the formation of secondary BN phase in the grain boundaries as the result of the reaction between AlN and surface B 2 O 3 impurity on the surface of TiB 2 particles. Weak intergranular BN phase formation limited the flexural strength but improved the fracture toughness up to the value of 7.8 Mp. m 1/2 for TiB 2 -AlN ceramics. The electrical resistivity of 0.0028 Ω was obtained for TiB 2 - 7.5 wt% AlN.