Low-temperature solution synthesis of nanosized hafnium carbide using pectin

Abstract

Nano-sized hafnium carbide was synthesized from organic–inorganic hybrid polymer based on polycondensation and carbothermal reduction reaction from pectin and hafnium tetrachloride followed by thermal treatment. Orthorhombic and monoclinic hafnia formed on pyrolysis which above 1300 °C transformed to hafnium carbide. Conversion of amorphous to crystalline hafnia was initiated at ~800 °C while the endothermic carbothermal reduction reaction started at ~1275 °C. Total yield of hafnium carbide was ~62%. The resulting carbide powders were equiaxed with narrow size distribution of crystallite size ~50 nm. SEM and EDX mapping confirm the uniform distribution of Hf and C. The high ceramic yield, uniform size particles, and simplicity of the process make it a promising route for polymer infiltration pyrolysis of carbon fiber/ultra high temperature composites.