Robocasting of reaction bonded silicon carbide/silicon carbide platelet composites

Abstract Pastes with a varying amount of uncoated SiC platelets (SiCplatelets) for the fabrication of reaction bonded silicon carbide (RBSC) were developed and the effect of the anisotropic particles on the microstructure and mechanical properties of the fabricated RBSC/SiCplatelets composites was studied. During printing the platelets align in printing direction due to shear forces. This texturization was confirmed by image analysis and EBSD measurement. The bending strength and the fracture toughness of about 470 MPa and 2.7 MPam1/2, respectively, did not change significantly after the addition of uncoated platelets, but showed comparable values according to the literature data for RBSC ceramics. Hardness and Young's modulus (17 GPa and 380 GPa) were also comparable to traditionally fabricated RBSC ceramics and showed a slight increase after the addition of platelets. SEM analysis of the fracture surfaces of the fabricated composites showed no pull-out and nearly no crack deflection, which may explain the constant values of the mechanical properties. Further work is therefore aimed at developing the paste filled with coated platelets. Although the influence of the uncoated platelets was small, the technological feasibility of producing textured RBSC/SiCplatelets composites using robocasting was demonstrated and the possibility to generate complex structures was successfully shown.