Fabrication and Properties of a Gel-Cast Dense Silicon Carbide Body

In this research, the effect of different parameters on the behavior of suspension rheology, as well as the physical and mechanical properties of green and sintered SiC bodies, were investigated. Viscosity values ​​for slurries containing 0.1, 0.3, 0.5, 0.7, 0.9 and 1.1 wt% of dispersant (Tetramethyl ammonium hydroxide ((CH3)4NOH, TMAH) were investigated, and the minimum viscosity was obtained for the slurry containing 0.7 wt% TMAH. The results showed that the highest amount of SiC powder that could be used without causing any serious problem was 37 vol.%. The monomers used in the research were metacrylamide (MAM) and N,Ń- methylenbisacrylamide (MBAM). Afterward, the effect of monomers content (MAM and MBAM) and ceramic load on the shrinkage and warpage of green bodies were investigated. The results demonstrated that increasing the amount of monomers decreases warpage rate (WP) and shrinkage rate (SK). Other than that, with increasing monomers ratio, both of these parameters increase uniformly. Subsequently, the samples were sintered for 1 h at 2150 °C. The results proved that the sample containing 37 vol.% of SiC with a monomers ratio of 3:1 and a total monomers content of 20 wt.% had the highest hardness, fracture toughness, and relative density, equal to 27.51 ± 1.25 GPa, 6.2 MPa.m1/2, and 96.89%, respectively.