Effects of Al2O3@Ni core-shell powders on the microstructure and mechanical properties of Ti(C,N) cermets via spark plasma sintering

Abstract

To investigate the effects of the core-shell powders on the microstructure and mechanical properties of Ti(C,N) cermets, Ni-coated Al2O3 (Al2O3@Ni) core-shell powders were made using the heterogeneous precipitation-thermal reduction method, and Ti(C,N) cermets with Al2O3@Ni added were made using spark plasma sintering (SPS). The results showed that the addition of powders prevents direct contact between Al2O3 and Ti(C,N) ceramic particles, that the distribution of Ni and Al2O3 in the matrix causes a more uniform discharge of SPS, that the grain size was smaller and the size difference between grains was smaller, and that fine grain strengthening improves the mechanical properties of cermet materials. When the sintering temperature was 1500 °C, the Ti(C,N) cermets had the best all-around mechanical performance; their flexural strength was 1277 ± 21 MPa, hardness was 17.06 ± 0.25 GPa, and fracture toughness was 7.42 ± 0.15 MPa·m1/2.