Fabrication of biomorphic ZrC/C ceramics by sol–gel and carbothermal reduction processing

Biomorphic ZrC/C ceramics were fabricated by infiltration of wood-derived biocarbon template with a novel ZrO2-sol using inorganic precursor zirconium oxynitrate as the source of zirconium and acetylacetone as chemical modifier, followed by subsequent high temperature pyrolysis and reaction treatment under argon at 1500 °C. The microstructure, phase composition, pore size distribution and mechanical properties of ZrC/C ceramic, as well as the conversion mechanism of wood to ZrC/C were investigated. The results showed that the impregnant was firstly decomposed to zirconia, and then reacted with carbon in the cellular wall to form ZrC at high temperature. The cellular morphology of biocarbon template was retained well in the resulting ceramics consisting of cubic ZrC and residual amorphous carbon. The biomorphic ZrC/C displayed a multimodal pore size distribution in the macro-size scale. Moreover, it was found that the mechanical properties of ZrC/C improved significantly on the basis of biocarbon template due to the formation of ZrC layer at inner cell walls.