Characterization of reactive spark plasma sintered (Zr,Ti)B2–ZrC–SiC composites

Abstract

This investigation aims to evaluate the influence of SiC introduction on the microstructure development, mechanical characteristics, and densification behavior of (Zr,Ti)B2–ZrC materials. Two specimens, with/without SiC addition, were manufactured from the starting materials of ZrB2 and TiC by reactive spark plasma sintering (SPS) at 1800 °C under 30 MPa for 5 min. Both samples reached relative density values higher than 99%; however, the SiC addition improved this value by ~0.5%, standing at 99.9%. The SiC incorporation into the (Zr,Ti)B2–ZrC system led to an ultrahigh temperature ceramic (UHTC) with considerable hardness and elastic modulus. The TiC additive was completely consumed over the sintering process, participating in the in-situ formation of TiB2 and ZrC as a result of a chemical reaction with the ZrB2 matrix. Thanks to the diffusion of Ti and Zr atoms into the ZrB2 and TiB2 phases, respectively, a solid-solution of (Zr,Ti)B2 formed with various compositions in different areas. Thanks to the synergistic effects of grain refinement and solid-solution formation, the (Zr,Ti)B2–ZrC–SiC sample reached excellent mechanical properties such as an elastic modulus of 495 GPa and a hardness of 31.2 GPa.