Preparation of TiC materials by oscillatory pressure sintering: densification mechanism, grain growth control, and mechanical properties

In this work, the densification kinetics of the unbonded TiC materials were studied based on the high-temperature creep theory to clarify the sintering evolution mechanism and microstructure evolution process. The ZrO2 nanoparticles were introduced to optimize and modify the microstructure and achieve low-temperature densification and refinement of the TiC materials. In addition, the mechanical properties of the unbonded TiC materials were systematically studied under different sintering temperatures. During the oscillatory pressure sintering, the mechanical properties of the TiC materials reached the optimal levels at the holding time of 1650°C and time of 30 min with the bending strength and fracture toughness of 902 MPa and 8.6 MPa·m1/2, respectively. Introducing ZrO2 nanoparticles into the TiC matrix did not reduce the densification temperature but significantly inhibited the growth of TiC grains. Introducing ZrO2 nanoparticles altered the fracture mode of the TiC materials from the mixture of intergranular and transgranular fractures to only transgranular fractures. The cracks propagated smoothly with minimal resistance, and t-ZrO2 was stabilized. Thus, the fracture toughness of the TiC materials decreased by 18%.