Zirconium carbide (ZrC) ceramics is an important candidate material for structural applications both at high temperature and intensive irradiation. However, its sensitivity to defects and cracks often causes low reliability and limited the application of ZrC ceramics. In this work, graphite nanoplatelets (GNPs) doped zirconium carbide ceramics were prepared by spark plasma sintering (SPS). The results show that the addition of GNPs not only improved the densification of ZrC ceramics but also inhibited grain growth of ZrC matrix phase. The GNPs were mainly located at the grain boundaries, and the c-axis of the disk-like GNPs preferred to align with the applied pressing direction during SPS. The preferred orientation of GNPs in the sintered ceramics resulted in anisotropic microstructure and fracture toughness of the material. Compared with the monolithic ZrC ceramics with a fracture toughness of 2.27 MPa m^1/2, GNPs doped ceramics shows higher fracture toughness. The fracture toughness of ZrC ceramics with 0.5, 1.5, 3 vol% GNPs are 2.70 MPa m^1/2, 3.03 MPa m^1/2 and 3.24 MPa m^1/2 measured on the surface perpendicular to the applied pressing direction and 3.43 MPa m^1/2, 3.66 MPa m^1/2 and 4.55 MPa m^1/2 measured on the surface parallel to the applied pressing direction, respectively. The crack deflection and re-initiation by GNPs are the main toughening mechanisms for the GNPs doped ZrC ceramics.

碳化锆（ZrC）陶瓷是高温和强辐射下结构应用的重要候选材料。然而，其对缺陷和裂纹的敏感性通常导致可靠性低，并且限制了ZrC陶瓷的应用。在这项工作中，通过火花等离子体烧结（SPS）制备了掺杂石墨纳米片（GNP）的碳化锆陶瓷。结果表明，加入GNPs不仅可以改善ZrC陶瓷的致密化，而且可以抑制ZrC基体相的晶粒长大。GNP主要位于晶界，并且盘状GNP的c轴优选在SPS期间与施加的压制方向对准。烧结陶瓷中GNP的优选取向导致材料的各向异性组织和断裂韧性。^1/2的GNP掺杂陶瓷具有更高的断裂韧性。在垂直于施加压力方向的表面上测得的ZrC陶瓷具有0.5、1.5、3％（体积百分比）的ZrC陶瓷的断裂韧性分别为2.70 MPa m ^1/ 2，3.03 MPa m ^1/2和3.24 MPa m ^1/2和3.43 MPa m在平行于施加压力方向的表面上分别测量到^1/ 2，3.66 MPa m ^1/2和4.55 MPa m ^1/2。GNP的裂纹偏转和重新初始化是掺杂ZrC陶瓷的GNP的主要增韧机理。