Doped boron carbide, primarily with Si and B, has exhibited significant resistance to the formation of amorphization bands, but suffers degradation in critical mechanical properties, like hardness and toughness. Our preliminary study showed that the addition of a secondary phase (i.e., titanium diboride) could compensate for the loss in hardness without compromising amorphization resistance. The composite was prepared from reaction sintering of a powder mixture of B4C, B, and SiB6 with up to% TiB2. In this work, optimal processing parameters, including temperature and pressure, have been investigated for superior performance. Results showed that a lower sintering temperature around 1600 °C could lead to full density with a less detrimental silica phase formed. A pressure of 25 MPa was adequate for densification if less TiB2 was added. The benchmark properties of the composite were evaluated as well, showing that with 20% TiB2 addition, comparable hardness (26 GPa) and significant improvement in toughness (30%) were achieved relative to commercial boron carbide. Moreover, limiting microstructural factors were identified for further improvement in the performance of the composite.
2021-04-07 08:00:00
