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Zirconium carbide (ZrC) ceramics have a high melting point, low neutron absorption cross section, and excellent resistance to the impact of fission products and are considered to be one of the best candidate materials for fourth-generation nuclear energy systems. ZrC ceramics with a high relative density of 99.1% were successfully prepared via pressureless sintering using a small amount of MoSi2 as an additive. The influence of the MoSi2 content on the densification behavior, microstructure, mechanical properties, and thermal properties of ZrC ceramics was systematically investigated. The results show that the densification of ZrC was significantly enhanced by the introduction of MoSi2 due to the formation of a liquid phase during sintering. In addition, the ZrC grains were refined due to the pinning effect of the generated silicon carbide. The flexural strength and Vickers hardness of ZrC ceramics with 2.5 vol% MoSi2 sintered at 1850 °C were 408 ± 12 MPa and 17.1 GPa, respectively, which were approximately 30% and 10% higher compared to the samples without the addition of MoSi2. The improved mechanical properties were mainly attributed to the high relative density (99.1%) and refined microstructure. [ABSTRACT FROM AUTHOR]

• SiC p /Al composites were prepared based on Fused Deposition Modelling (FDM) • Higher SiC volume fraction were obtained compared to other additive manufacturing methods. • complex-structure composites were prepared with excellent properties. SiC p /Al composites are widely used in space vehicles, electronic packaging, automobiles, rail vehicles and other fields due to their excellent mechanical and thermal properties. Complex-shaped SiC p /Al parts are usually manufactured by mechanical processing, which is expensive and time-consuming due to the high hardness of SiC phase. As a highly effective 3D molding method, Fused Deposition Modelling (FDM) of the complex-structure SiC p /Al composites was reported for the first time in this paper. SiC p /Al composites was densified by pressureless infiltration after FDM, and as-acquired bulk possessed high densification of 92.67 % and the SiC volume fraction of 43.2 %. Moreover, excellent performances were also presented, including flexural strength of 211 MPa, thermal conductivity of 112(W/m·K), and the thermal expansion coefficient of 8.67 × 10-6K−1. [ABSTRACT FROM AUTHOR]