Mechanical properties and microstructure of Al2O3/TiB2 and Al2O3/TiB2/GNPs ceramic tool materials prepared by spark plasma sintering

Abstract

Al2O3/TiB2 and Al2O3/TiB2/graphene nanoplatelets (GNPs) ceramic tool materials were prepared by spark plasma sintering, and the effect of the sintering parameters and different GNPs addition amounts on the densification, mechanical properties, and microstructure have been investigated. The optimum comprehensive mechanical properties of Al2O3/TiB2 were obtained at synthesis conditions of 1525 °C under 30 MPa for 5 min. However, the addition of GNPs could promote the densification and improve the mechanical properties. The results show that the ceramic tool material with 0.3 wt% GNPs exhibits mechanical properties superior to those of pure Al2O3/TiB2; the fracture toughness increases by 41.6% and reaches the maximum value of 7.35 ± 0.23 MPa m1/2, and the flexural strength increases by 6.4%–661 ± 16 MPa. The toughening mechanisms of Al2O3/TiB2/GNPs are explained by graphene pull-out, crack bridging, branching and deflection.