Influence of silicon carbide addition on the microstructural development of hot pressed zirconium and titanium diborides

The influences of adding SiC on the microstructure and densification behavior of ZrB₂ and TiB₂ ceramics, hot pressed at 1850 °C for 60 min under 20 MPa, were investigated. The sintered samples were characterized by SEM, EDS and XRD methods. A fully dense TiB₂-based ceramic was obtained by adding 30 vol% SiC. The grain size of ZrB₂ or TiB₂ matrices in the final microstructures decreased with increasing SiC content. The XRD analyses, microstructural characterization as well as thermodynamical calculations proved the in-situ formation of TiC in the SiC reinforced TiB₂-based composites. The interfaces between ZrB₂ and SiC grains in the SiC reinforced ZrB₂-based composites were free of any impurities or tertiary interfacial phases such as ZrC. This result was consistent with the X-ray diffraction pattern and thermodynamics.