Effect of Heating Rate on the Synthesis and Sintering of Ternary Carbide Zr2Al3C4 through Spark Plasma Sintering

The Nearly Full Dense Zr2Al3C4 Ceramic Was Successfully Fabricated at 1800 °C for 10 min under a Uniaxial Load of 20 MPa in Vacuum by the Spark Plasma Sintering Process, Using a Mixture of Zr, Al and Graphite Powders as Raw Materials. The Reaction Route of Synthesis as Well as the Sintering Conditions of the SPS Technique Were Discussed Based on X-Ray Diffraction Results. The Results Showed that the Heating Rate Can Largely Affect the Loss and Aggregation of Molten Al. Moreover, the Contents of Al4O4C and the Elevated Sintering Temperature Were Beneficial for the Synthesis of Zr2Al3C4 Ceramic. The Microstructures of the Samples Were Observed by Scanning Electron Microscopy, Showing that the as-Synthesized Zr2Al3C4 Has an Anisotropic Microstructure Consisting of Elongated Grains. Compared to the Hot-Pressing, the Starting Temperature for the Formation of Zr3Al3C5 and Al4O4C Phases Was Rather Low. It Indicates that the SPS Technique Can Rapidly Synthesize Zr2Al3C4 from the Zr/Al/C Powders in a Relatively Low Temperature Range. The Mechanical Properties of the Sintered Materials Were Also Investigated, Including the Hardness of 11.66±0.34 GPa, and Fracture Toughness of 4.0 ± 0.4 MPa×m1/2.