Fabrication of ZrC/ZrB<sub>2</sub>/C Composites Having High Mechanical Properties at Elevated Temperatures

Ultra-high temperature ceramics (UHTCs) are most recently getting much attention for structural parts of hypersonic missiles with their cruising speed more than Mach 5. Most the UHTCs poor sinterability carbides, nitrides, and borides. Therefore, they have been studied developed a long time. However, there still many problems to solve. In this paper, based on solid-state reaction presented as an equation (x + y)·ZrC 2·y·B → x·ZrC y·ZrB2 y·C, three-phase ZrC/ZrB2/C composites fabricated from ZrC amorphous B powders using pulsed electric-current pressure sintering at 1373 2173 K 6.0 × 102 s under 50 MPa in vacuum. = 30/70/C~70/30/C vol% relative densities Dr 96.6 98.7% were obtained 2073 K. The 60/40/C composite revealed high bending strength σb (554 MPa), Vickers hardness Hv (19.2 GPa) moderate fracture toughness KIC (5.25 MPa·m1/2) room temperature. Furthermore, all showed elastic deformation up 1873 600 temperature, addition, some higher 900 same These mechanical behaviors discussed those simple binary ZrC/ZrB2 which conditions except starting materials. best properties (474 (18.5 GPa), (4.45 400 - 700 Overall, composites, nevertheless including soft carbon, composites.