Synthesis and Evolution of Zirconium Carbide via Sol–Gel Route: Features of Nanoparticle Oxide–Carbon Reactions

Abstract

A sol–gel route was used to synthesize nanocrystalline zirconium carbide (ZrC). The starting materials were zirconium propoxide, with carbon introduced by furfuryl alcohol (FA). A block copolymer surfactant was used to homogenize the oxide and carbon components. ZrC was produced at a low temperature of 1250°C and complete conversion achieved at 1450°C. The powder was nanocrystalline size less than 100 nm. Phase changes were studied using X‐ray diffraction and Raman spectroscopy. Rietveld analysis followed the changes in crystallite size and lattice parameters of the phases during carbothermal reduction. Morphology changes were observed using nitrogen gas sorption. High‐resolution TEM and EDS were used to image the carbide lattice, surface oxides, and graphene‐like carbons. The results indicate that nanoparticle carbothermal synthesis involves agglomeration and necking as the most viable mode of mass transport to complete the carbothermal reduction.

Creation of Titanium and Zirconium Carbide Fibers with the Forcespinning Technique

“…Figure a shows peaks consistent with ZrO 2 in a carbon matrix (carbon is amorphous) after firing at 550°C/5 h in nitrogen, and Fig. b shows a trace collected from fibers after carbothermal reduction at 1450°C, displaying peaks consistent with ZrC . As was shown in Fig.…”

Zirconium carbide, hafnium carbide and their ternary carbide nanoparticles by an in situ polymerization route

“…8b) shows part of a representative coke particle in detail and reveals that the coke consists of wellcrystallized nanoparticles with size ranging from 10 to 20 nm, which are surrounded and isolated from one another by amorphous regions and whose size is consistent with the average size estimated by the Scherrer formula. 46 Here in our case, we come up with a new multi-reaction sites theory. The coke particles are thus best described as ZrO 2 /carbon nanocomposites consisting of metal oxide crystallites, about 10 nanometers in size, highly dispersed within an amorphous carbon matrix.…”

Carbothermal conversion of self‐supporting organic/inorganic interpenetrating networks to porous metal boride monoliths

“…Unlike silicon carbide, which can be directly formed by pyrolyzing Si‐C bonded polymeric precursors (eg, polycarbosilane), MB materials from liquid‐based processes are routinely obtained by carbothermal reductions at high temperatures (>1300°C) among carbon, metal, and boron oxides . It is more common to obtain powdery MB materials via liquid‐based processes under ambient pressure drying, and sometimes even under supercritical drying conditions . For synthesizing porous MB monoliths via sol‐gel approach, the monoliths have to survive at least two critical processes: drying and pyrolysis at high temperatures.…”