Densification and enhancement of SiC particulate reinforced fine grain SiC ceramic

Dense sintering of SiC nanopowder under low temperature and pressure remains a big challenge, because of the great resistance caused by the severe agglomeration of nanopowder. A novel sintering strategy is proposed to prepare SiC composite ceramics by sintering the mixture of SiC nanopowder and SiC micron powder at low temperature and pressure. The SiC micron powder was in the size of 100 µm with little sintering activity, which was designed as a pressure conductor to promote the densification of SiC nanopowder. Experimental results showed that the SiC micron powder had a significant effect on increasing of the sintering density of nanopowder and improving the mechanical properties of SiC ceramics. An SiC composite ceramic with a relative density of 98%, a Vickers hardness of 22.6 GPa, and a fracture toughness of 5.43 MPa m1/2 could be sintered by spark plasma sintering under 1700°C and 30 MPa by adding 30 wt.% 100 µm SiC micron powder as reinforcements.