Spark plasma sintering of Al-doped ZrB2–SiC composite (original) (raw)

This research presents the influence of Al addition on microstructure and mechanical behavior of ZrB 2-SiC ultra-high temperature ceramic matrix composite (UHTCMC) fabricated by spark plasma sintering (SPS). A 2.5 wt% Al-doped ZrB 2-20 vol% SiC UHTCMC was produced by SPS method at 1900 °C under a pressure of 40 MPa for 7 min. The microstructural and phase analysis of the composite showed that aluminum-containing compounds were formed in-situ during the SPS as a result of chemical reactions between Al and surface oxide films of the raw materials (i.e. ZrO 2 and SiO 2 on the surfaces of ZrB 2 and SiC particles, respectively). The Al dopant was completely consumed and converted to the intermetallic Al 3 Zr and Al 4 Si compounds as well as Al 2 O 3 and Al 2 SiO 5. A relative density of 99.8%, a hardness (HV5) of 21.5 GPa and a fracture toughness (indentation method) of 6.3 MPa.m 1/2 were estimated for the Al-doped ZrB 2-SiC composite. Crack bridging, branching, and deflection were identified as the main toughening mechanisms.