Microstructural characterization and mechanical behaviours of TiN-graphite composites fabricated by spark plasma sintering.

The effects of milling time on the particle size distribution (PSD), densification, microstructure, hardness and fracture toughness of spark plasma sintered (SPS) TiN+graphite ceramic were studied. TiN with varying amount of graphite (1, 3, and 5 wt%) were milled at different milling time (8, 24 and 40 h), thereafter sintered at sintering temperature of 1800 °C, holding time of 10 min and pressure of 50 MPa. The relative density and hardness increased as milling time progressed from 24 to 40 h, however, the relative density, hardness, and particle size decreased after 8 h of milling. The microstructural analyses showed that a fully sintered TiN+graphite compact could be achieved at sintering temperature of 1800 °C, with no significant grain growth. Residual stress effect of TiN+5 wt% graphite composite was analyzed using XRD method and the result indicated that there is no significant residual stress on the sample. The relative density, Vickers hardness and fracture toughness of TiN+ 1 wt% Gr, milled for 40 h were 99.24%, 13.90 GPa and 4.0 MPa.m1/2 respectively. Unlabelled Image • Microstructures and mechanical behaviour of TiN-Graphite composites. • The sample preparation was carried out in order to highlight the impact of powder properties and performance. • Sub-micron sizes of each powder were determined using Microtrac particle size distribution, Raman spectroscopy and XRD analysis. • Both the rim and core phases in the structure show uniform phases with similar patterns of diffractions. • The inner and outer rims present distinctive direction of Fcc-phases with equiaxed grains using EBSD. [ABSTRACT FROM AUTHOR]