Dependence of the Reactivity of the Finely Divided System Ta2O5–HfO2–C on the Xerogel Carbonization Temperature.

The effect of the temperature of carbonization of xerogels on the chemical activity of the obtained materials in the Ta₂O₅–HfO₂–C system was studied to create an energy-efficient method for producing ceramic materials based on the TaC–HfC system using reactive hot pressing or spark plasma sintering. A new method was developed to form a tantalum–hafnium–polymer-containing gel by creating interpenetrating organic–inorganic networks with the simultaneous initiation of hydrolysis of metal–containing precursors and polymerization of furfuryl alcohol (acid catalysis with formic acid). Samples of the Ta₂O₅–HfO₂–C system with different reactivities in the carbothermal synthesis of complex carbides were obtained based on the xerogel produced after drying using carbonization under dynamic vacuum conditions at various temperatures (400, 700, and 1000°C). Their elemental and phase composition, microstructure and thermal behavior in an air flow were investigated. The powder synthesized at a minimum temperature of 400°C had the maximum reactivity but also contained rather much (3–4 wt %) unpyrolyzed organic fragments, which should be taken into account in planning high-temperature consolidation of carbide ceramics. [ABSTRACT FROM AUTHOR]