Transition metal diboride-silicon carbide-boron carbide ceramics with super-high hardness and strength |
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| Affiliation: | 1. School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China;2. State Key Laboratory of Electronic Thin Films and Integrated Devices, Chengdu, China;3. National Engineering Research Center of Electromagnetic Radiation Control Materials, Chengdu, China;1. College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211100, China;2. Key Laboratory of Materials Preparation and Protection for Harsh Environment (Nanjing University of Aeronautics and Astronautics), Ministry of Industry and Information Technology, Nanjing 211106, China;3. School of Materials Science and Engineering, Nanjing Institute of Technology, Nanjing 211167, China;1. Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China;2. State Key Laboratory of Green Building Materials, China Building Materials Academy, Beijing 100000, China |
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| Abstract: | Three phase boride and carbide ceramics were found to have remarkably high hardness values. Six different compositions were produced by hot pressing ternary mixtures of Group IVB transition metal diborides, SiC, and B4C. Vickers’ hardness at 9.8 N was ~31 GPa for a ceramic containing 70 vol% TiB2, 15 vol% SiC, and 15 vol% B4C, increasing to ~33 GPa for a ceramic containing equal volume fractions of the three constituents. Hardness values for the ceramics containing ZrB2 and HfB2 were ~30% and 20% lower than the corresponding TiB2 containing ceramics, respectively. Hardness values also increased as indentation load decreased due to the indentation size effect. At an indentation load of 0.49 N, the hardness of the previously reported ceramic containing equal volume fractions of TiB2, SiC and B4C was ~54 GPa, the highest of the ceramics in the present study and higher than the hardness values reported for so-called “superhard” ceramics at comparable indentation loads. The previously reported ceramic containing 70 vol% TiB2, 15 vol% SiC, and 15 vol% B4C also displayed the highest flexural strength of ~1.3 GPa and fracture toughness of 5.7 MPa·m1/2, decreasing to ~0.9 GPa and 4.5 MPa·m1/2 for a ceramic containing equal volume fractions of the constituents. |
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| Keywords: | Hot-pressing Borides Carbides Mechanical properties |
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