Investigations on synthesis of HfB2 and development of a new composite with TiSi2 |
| |
Authors: | JK Sonber TSRCh Murthy C Subramanian Sunil Kumar RK Fotedar AK Suri |
| |
Affiliation: | 1. Materials Group, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India;2. Post Irradiation Examination Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India |
| |
Abstract: | This paper presents the results of investigation carried out on synthesis and densification of monolithic HfB2 and the effect of TiSi2 as sinter additive. Pure phase HfB2 was prepared by boron carbide reduction of HfO2 and hot pressed to full density with the addition of TiSi2. Isothermal oxidation study of this composite was carried out at 850 °C up to 64 h. Formation of HfB2 was seen at 1200 °C but pure HfB2 was formed at a much higher temperature of 1875 °C in vacuum. Hot pressing of HfB2 at 1850 °C and 35 MPa pressure gave a compact of 80% TD. Addition of TiSi2 helped in achieving a much higher density at a lower temperature of 1600 °C and a pressure of 20 MPa. A fully dense composite of HfB2 and TiSi2 was obtained with 15% TiSi2. Hardness and fracture toughness of this composite were 27.4 ± 1.9 GPa and 6.6 ± 0.2 MPa m1/2, respectively. Considerable deflection was observed in the crack propagation in composites. Oxidation studies indicated the formation of HfO2, SiO2, TiO2 and HfSiO4 with some glassy phase and the composite with 15% TiSi2 was seen to be completely covered with a protective glassy layer. |
| |
Keywords: | HfB2 TiSi2 Composite Synthesis Densification Microstructure Oxidation studies |
本文献已被 ScienceDirect 等数据库收录! |
|