Research On Synthesis Of Carbon-encapsulated Iron Nanoparticles By Gaseous Detonation (Deflagration) Method

The article explores a new method——gaseous detonation (deflagration) prepared carbon-encapsulated iron nanoparticles. Ferrocene is the precursor, and the mixture gas including hydrogen and oxygen or hydrogen and air is the explosion source.First, theoretical calculations of detonation pressure, detonation velocity, density and detonation temperature are conducted through the C-J classical detonation theory and first law of thermodynamics when the mixture gas react in the self-made tube. High speed photography and IDTS-3850stress testing equipment are used to measure the detonation pressure and detonation velocity. Comparing the measurement results and the theoretical results, error is less than5%. According to the detonation temperature, a feasibility analysis of the synthesis of Carbon-encapsulated Iron nanoparticles is conducted through the Iron-Carbon alloy phase diagram.Second, an experiment is conducted using hydrogen and air as the explosion source and changing the precursor mass or the initial temperature, which successfully synthesize carbon-encapsulated Iron nanoparticles. But the products all contain impurities-Ferrocene. Pure nanomaterial is got through purifying. Analysis is made by means of XRD、TEM, and the results show that, under the same conditions, the higher the quality of precursor is, the more uniform the particle size is, but the more serious the reunion is; The higher the initial temperature is, the more uniform particle size is, but the more the content of the iron-carbon compound is.Third, an experiment is conducted using hydrogen and oxygen as the explosion source and changing the precursor mass or the initial temperature hydrogen and oxygen ratio. Ferrocene is not found in products. Analysis is made by means of XRD、TEM, and the results show that, when the precursor is less than a certain quality, the products are Fe and FeO. The trends are consistent with the one using hydrogen and air as the explosion source under the same conditions. The difference is that the cladding layer is more thicken and the iron carbon compounds are less.At last, the post-processing of iron-carbon compound in the synthesized products is carried out which takes annealing process under200℃and260℃. Analysis is made by means of XRD、TEM, the results show that the Fe3C basically disappears and the thickness of cladding layer increases. The trends of the product obtained with hydrogen and air detonation are significantly higher than the trends of product obtained with hydrogen and oxygen detonation. By means of VSM, the products show good paramagnetic.