Microstructural and nanoindentation study of TaN incorporated ZrB₂ and ZrB₂-SiC ceramics

This study assessed the sinterability and microstructure of ZrB₂-SiC-TaN and ZrB₂-TaN ceramics. Spark plasma sintering at 2000 °C and 30 MPa for 5 min produced both ceramics. The relative density of ZrB₂ ceramic containing TaN was 95.3%; the addition of SiC increased this value to 98.1%. SiC's contribution to the elimination of ZrB₂ surface oxides was the primary factor in the advancement of densification. The in situ formation of hexagonal boron nitride at the interface of TaN and ZrB₂ was confirmed by high-resolution transmission electron microscopy, field emission-electron probe microanalyzer, X-ray diffractometry, and field emission scanning electron microscopy. Moreover, the in situ graphite might be produced as a byproduct of the SiC-SiO₂ process, hence boosting the reduction of oxide compounds in the ternary system. The SiC compound had the highest hardness (29 ± 3 GPa), while the ZrB₂/TaN interface exhibited the greatest values of elastic modulus (473 ± 26 GPa) and stiffness (0.76 ± 0.13 mN/nm).