Effects of Grain Grading on Microstructures and Mechanical Behaviors of Pressureless Solid‐State‐Sintered SiC

S‐SiC ceramics with >96% of densification degree were derived from 0.8‐ to 8.6‐μm graded powders for the first time after sintered at 2210°C. Grain grading generated a 21.8% increase in green density and a 40.8% decrease in sintering shrinkage (low to 12.2%). The introduction of micrometer‐sized coarse particles suppressed abnormal grain growth owing to their pinning effect, thus resulting in equiaxial grains. Dramatically improved fracture toughness peaked to 3.77 MPa·m ^1/2 at 50 wt% of added coarse powder. Sintering mechanism of graded powders can be deduced as the bonding of coarse SiC particle through solid‐state sintering of fine powder.