Spark plasma sintering of UHTC powders obtained by self-propagating high-temperature synthesis
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Fully dense ZrB2–SiC and HfB2–SiC ultra-high-temperature ceramics (UHTCs) composites are fabricated by first synthesizing via self-propagating high-temperature synthesis (SHS) the composite powders from B4C, Si, and Zr or Hf reactants, and subsequently consolidating the product by spark plasma sintering (SPS) without the addition of any sintering aid. It was found that the SHS technique leads to the complete conversion of reactants to the desired products and the SPS allows for the full consolidation (>99.5% relative density) under the optimal operating conditions of 1800 °C/20 min/20 MPa and 1800 °C/30 min/20 MPa, for the cases of ZrB2–SiC and HfB2–SiC, respectively. Based on the results reported in this work, it can be stated that the combination of SHS and SPS methods represents a particularly rapid and convenient preparation route (lower sintering temperature and processing time) for UHTCs as compared to the techniques available in the literature for the fabrication of analogous products.
KeywordsSpark Plasma Sinter Spark Plasma Sinter Process Zirconium Diboride Dwell Temperature Hafnium Diboride
IM Innovative Materials s.r.l. (Italy) is gratefully acknowledged for granting the use of SPS apparatus. We also gratefully acknowledge the Regione Autonoma della Sardegna (Italy) for financial support through the project POR Sardegna 2000–2006 (Misura 3.13). In addition the authors would like to thank Dr. Luigi Scatteia from CIRA (Italy) for the measurements of resistance to oxidation of SPS samples.
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