Synthesis, Physical, and Mechanical Properties of Bulk Zr 3 Al 3 C 5 Ceramic

An in situ reactive hot‐pressing process using zirconium (zirconium hydride), aluminum, and graphite as staring materials and Si and Y 2 O 3 as additives was used to synthesize bulk Zr 3 Al 3 C 5 ceramics. This method demonstrates the advantages of easy synthesis, lower sintering temperature, high purity and density, and improved mechanical properties of synthesized Zr 3 Al 3 C 5 . Its electrical and thermal properties were measured. Compared with ZrC, Zr 3 Al 3 C 5 has a relatively low hardness (Vickers hardness of 12.5 GPa), comparable stiffness (Young's modulus of 374 GPa), but superior strength (flexural strength of 488 GPa) and toughness (fracture toughness of 4.68 MPa·m 1/2 ). In addition, the stiffness decreases slowly with increasing temperature and at 1600°C remains 78% of that at ambient temperature, indicating that Zr 3 Al 3 C 5 is a potential high‐temperature structural ceramic.