Microstructure, mechanical, thermal, and oxidation properties of a Zr2[Al(Si)]4C5–SiC composite prepared by in situ reaction/hot-pressing

The microstructure, mechanical and thermal properties, as well as oxidation behavior, of in situ hot-pressed Zr2[Al(Si)]4C5–30 vol.% SiC composite have been characterized. The microstructure is composed of elongated Zr2[Al(Si)]4C5 grains and embedded SiC particles. The composite shows superior hardness (Vickers hardness of 16.4 GPa), stiffness (Youngʹs modulus of 386 GPa), strength (bending strength of 353 MPa), and toughness (fracture toughness of 6.62 MPa m1/2) compared to a monolithic Zr2[Al(Si)]4C5 ceramic. Stiffness is maintained up to 1600 °C (323 GPa) due to clean grain boundaries with no glassy phase. The composite also exhibits higher specific heat capacity and thermal conductivity as well as better oxidation resistance compared to Zr2[Al(Si)]4C5.