Porous (SiCw-Si3N4w)/(Si3N4-SiC) composite with enhanced mechanical performance fabricated by 3D printing

SiC whisker and Si3N4 whisker-reinforced Si3N4-SiC ((SiCw-Si3N4w)/(Si3N4-SiC)) composite was synthesized by 3D printing for the first time, by the combination of printed-Si-body nitridation and chemical vapor infiltration-SiC methods. The mechanical properties of the composite could be optimized through the adjustment of SiCw content and load direction. A SiCw content of 3 wt% was found to be the optimal scheme, and accordingly, the average bulk density increased by 22.4%, the bending strength increased by 63.6%, the compressive strength parallel to the printing layer increased by 404.8%, and the compressive strength perpendicular to the printing layer increased by 157.1%, compared with the bulks without whiskers. The enhanced mechanical performance was mainly attributed to the process of densification by CVI, and the effect of the homogeneous whiskers bridging, pull-out and deflecting crack to expend energy. The achieved indices meet the requirements for 3D-printed porous ceramic matrix composite targeted for commercial and military field applications.