Fabrication of ZrC/ZrB₂/C Composites Having High Mechanical Properties at Elevated Temperatures  

作　　者：Kai Matsumoto Masaki Kato Ken Hirota Toshiyuki Nishimura Kai Matsumoto;Masaki Kato;Ken Hirota;Toshiyuki Nishimura(Department of Molecular Chemistry & Biochemistry, Faculty of Science & Engineering, Doshisha University, Kyotanabe, Japan;National Institute for Materials Science, Tsukuba, Japan)

机构地区：[1]Department of Molecular Chemistry & Biochemistry, Faculty of Science & Engineering, Doshisha University, Kyotanabe, Japan [2]National Institute for Materials Science, Tsukuba, Japan

出　　处：《Materials Sciences and Applications》2022年第4期232-248,共17页材料科学与应用期刊（英文）

摘　　要：Ultra-high temperature ceramics (UHTCs) are most recently getting much attention for structural parts of hypersonic missiles with their cruising speed of more than Mach 5. Most of the UHTCs are poor sinterability carbides, nitrides, and borides. Therefore, they have been studied and developed for a long time. However, there are still many problems to solve. In this paper, based on the solid-state reaction presented as an equation of (x + y)·ZrC + 2·y·B → x·ZrC + y·ZrB₂ + y·C, three-phase ZrC/ZrB₂/C composites have been fabricated from ZrC and amorphous B powders using pulsed electric-current pressure sintering at 1373 to 2173 K for 6.0 × 10² s under 50 MPa in a vacuum. ZrC/ZrB2/C = 30/70/C~70/30/C vol% composites with the relative densities D_r of 96.6 to 98.7% were obtained at 2073 K. The 60/40/C vol% composite revealed high bending strength σ_b (554 MPa), Vickers hardness H_v (19.2 GPa) and moderate fracture toughness K_IC (5.25 MPa·m^1/2) at room temperature. Furthermore, all composites showed elastic deformation up to 1873 K and revealed σ_b more than 600 MPa at this temperature, in addition, some composites showed higher σ_b than 900 MPa at the same temperature. These high mechanical behaviors are discussed with those of the simple binary ZrC/ZrB₂ composites which were fabricated under the same conditions except for their starting materials. The best mechanical properties of binary composites were σ_b (474 MPa), H_v (18.5 GPa), and K_IC (4.45 MPa·m^1/2) at room temperature, and σ_b of 400 - 700 MPa at 1873 K. Overall, three-phase composites, nevertheless including soft carbon, have higher mechanical properties than the binary composites.Ultra-high temperature ceramics (UHTCs) are most recently getting much attention for structural parts of hypersonic missiles with their cruising speed of more than Mach 5. Most of the UHTCs are poor sinterability carbides, nitrides, and borides. Therefore, they have been studied and developed for a long time. However, there are still many problems to solve. In this paper, based on the solid-state reaction presented as an equation of (x + y)·ZrC + 2·y·B → x·ZrC + y·ZrB₂ + y·C, three-phase ZrC/ZrB₂/C composites have been fabricated from ZrC and amorphous B powders using pulsed electric-current pressure sintering at 1373 to 2173 K for 6.0 × 10² s under 50 MPa in a vacuum. ZrC/ZrB2/C = 30/70/C~70/30/C vol% composites with the relative densities D_r of 96.6 to 98.7% were obtained at 2073 K. The 60/40/C vol% composite revealed high bending strength σ_b (554 MPa), Vickers hardness H_v (19.2 GPa) and moderate fracture toughness K_IC (5.25 MPa·m^1/2) at room temperature. Furthermore, all composites showed elastic deformation up to 1873 K and revealed σ_b more than 600 MPa at this temperature, in addition, some composites showed higher σ_b than 900 MPa at the same temperature. These high mechanical behaviors are discussed with those of the simple binary ZrC/ZrB₂ composites which were fabricated under the same conditions except for their starting materials. The best mechanical properties of binary composites were σ_b (474 MPa), H_v (18.5 GPa), and K_IC (4.45 MPa·m^1/2) at room temperature, and σ_b of 400 - 700 MPa at 1873 K. Overall, three-phase composites, nevertheless including soft carbon, have higher mechanical properties than the binary composites.

关 键 词：ZRC ZrB₂ C COMPOSITES Pulsed Electric-Current Pressure Sintering Mechanical Properties 

分 类 号：TB3[一般工业技术—材料科学与工程]