Mechanical properties of SiB_6 addition of carbon sintered body

摘要

Boride material is said as the useful material, which has high melting point and high strength. B_4C in carbide is very hard at the next of the diamond and cubic-BN in the Mohs hardness and B_4C has excellent chemical stability and high strength. B_4C is being used as the polishing material from the hardness. However, it is difficult to make sintered body from high melting point (2623 K). Several silicon boride phases such as SiB_4, SiB_6, SiB_(6-x), SiB_(6+x), and Si_(11)B_(31), were previously reported. Silicon hexaboride (SiB_6) has proved to be a potentially useful material because of its high degree of hardness, moderate melting point (2123 K), and low specific gravity. We studied the preparation of SiB_6-B_4C-SiC sintered body in this report. We knew experientially that SiB_6 reacts with carbon at the high temperature, and forms B_4C or SiC. Carbon addition SiB_6 sintered body produced by hot pressing and reaction sintering that sintering condition was 1973 K for 3.6 ks in vacuum under a pressure of 25 MPa. The relative density of sintered bodies (SiB_6-0,5,10,15wt percent C) was approximately 100 percent. Characterization of mechanical properties was used indentation, Vickers hardness and thermal expansion coefficient. The Vickers hardness of SiB_6-10wt percent C showed 26 GPa.