Synthesis and formation mechanism of ZrC-SiC-TiC ceramic powders with high-sinterability via sol-gel process and carbothermal reduction

In this work, high-sinterability ZrC-SiC-TiC ceramic powders were synthesised through a sol-gel approach coupled with subsequent carbothermal reactions. Specifically, MgCl2 was utilised as an additive to enhance the sintering activity of the powders. Experimental results revealed that the introduction of Mg and variation in Zr/Ti molar ratios significantly influenced the phase and morphological evolution of the precursor. In the form of a Mg-Si-O liquid phase, Mg promoted carbothermal reduction and solid-solution reactions. It ultimately remained as amorphous Mg-Si-O oxide in the final ZrC-SiC-TiC ceramic powders, effectively improving the sintering activity of ceramic powders. Consequently, dense Mg-modified ZrC-SiC-TiC ceramics with high relative density up to 99.2 % were successfully fabricated by spark plasma sintering at 1700 C-degrees and 30 MPa.