Hot Pressing and Characterization of ZrB₂-SiC-MoSi₂ Composite

Abstract:

Transition metal diborides, especially zirconium and hafnium diboride are potential ceramic material for ultra high temperature applications above 1800°C. These borides are characterized by high melting point, formation of high melting point oxides, good oxidation resistance and excellent thermo-mechanical properties. In this present exploration, zirconium diboride (ZrB₂) has been selected for its moderate density (6.09 gm/cc) and better oxidation resistance compared to high density hafnium diboride (11.2 gm/cc). The developed ZrB₂ composite in the present study contains 10 wt. % SiC and 10 wt. % MoSi₂ as sintering additives. SiC and MoSi₂ were added to improve the thermal shock resistance and sinterability of the ultra high temperature ceramics (UHTCs). Vacuum hot pressing was carried out at 1800°C for a holding period of 30 minutes and applied pressure of 30 MPa. Attractive feature of this ZrB₂ composite is good machinability due to better electrical conductivity and complicated shapes can be realized easily through electro discharge machining (EDM) process. Detailed XRD phase analysis and microstructural investigation of the polished and fractured composites was carried out using SEM. Mechanical and thermal properties tests have been carried out for the optimized ZrB₂ composite material.

• Periodical: Materials Science Forum (Volumes 830-831)
• Pages: 421-424
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.830-831.421
• Online since: September 2015
• Authors: T. Venkateswaran*, M. Agilan, D. Sivakumar, Bhanu Pant
• Keywords: Hot Pressing, Molybdenum Disilicide (MoSi₂), Silicon Carbide (SiC), Zirconium Diboride (ZrB₂)

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