Effect of different filler materials on the microstructure and mechanical properties of SiCSiC joints joined by spark plasma sintering

The SiC ceramic was joined via spark plasma sintering (SPS) using 4.5 wt% yttria partially stabilized zirconia (4.5YSZ) powder and 4.5YSZ+20 wt%Al2O3 powder mixture as fillers. The 4.5YSZ powder was synthesized by sol-gel method. The effects of different filler materials on the microstructure and mechanical properties of the SiC joints were investigated. Based on the X-ray diffraction and scanning electron microscope analyses, as well as three-point bend tests, the SiC joint with 4.5YSZ+20 wt%Al2O3 powder mixture as the filler material possesses higher flexural strength of 107.3 MPa at room temperature. The superior flexural strength of the SiC joint using the 4.5YSZ+20 wt%Al2O3 filler is attributed both to the carbothermic reaction and element diffusion at the SiC/4.5YSZ+20 wt%Al2O3 interface during the joining process.