Synthesis and densification of ultra-fine ZrC powders-effects of C/Zr ratio

The excess carbon and oxygen contents of ZrC nano-powders was controlled, and the resultant effects on the densification of ZrC was analyzed. The particle size of the synthesized ZrC powder was about 200 non and its oxygen content was 0.49 wt%. The good results can be attributed to the rapid heating and cooling rate, the beneficial effects of current, and the relatively low synthesis temperature by using SPS (Spark plasma sintering) for the powder synthesis. The homogeneous distribution between reactants was an important factor to minimize the formation of excess carbon. With increasing the amount of carbon in the raw powder mixture, the oxygen content of ZrC powders decreased and the densification was suppressed. The decrease of excess carbon content, the presence of oxygen in the ZrC lattice, and the fine particle size promoted the sintering of ZrC ceramics without any additives at relatively low temperature and pressure (1750 degrees C, 40 MPa).