Interface and defect characterization in hot-pressed ZrB₂-SiC ceramics

ZrB₂ is interesting for thermal protection materials because of favorable thermal stability, mechanical properties and oxidation resistance. ZrB₂-20 vol.% SiC composite was prepared by hot-pressing at 2000 °C and 30 MPa. Microstructures and interfacial characterization were investigated by high resolution transmission electron microscopy. SiC polytype was formed as 6H structure in hot-pressed ZrB₂-SiC ceramics. Numerous edge dislocations were found in ZrB₂ grains. There was no interfacial amorphous layer or transition layer at the ZrB₂/6H-SiC interface. Note also that since only one of the constituents (ZrB₂ or SiC) was oriented along a proper zone axis, no evident orientation relationship was observed between SiC or ZrB₂.