Preparation Of Nanosize Iron Particles/Carbon Materials

Nano-metal/carbon composite is a new functional material, which can be widely used as electronic, electric, electromagnetic shield materials, oxidation/reduction catalysts, antibacterial materials and special active carbon etc. Presently, most researches focused on the synthesis of nano-metal/carbon from organometallic polymers and macromolecular-metal complexes , which led to some problems, such as complicated process and difficulty of metal content control. In this thesis, a model aromatic hydrocarbon, e.g., naphthalene and a petroleum refined residue were used as the raw carbon sources and ferrocene as metal source to synthesize the special nano-iron/carbon material through condensation-solvent extraction-carbonization processes. The effects of preparation parameters on the pyridine insoluble fractions and morphologies of nano-iron/carbon were studied and the structural features and magnetic property were investigated by SEM, TEM, XRD, HRTEM, XPS, VSM etc. The formation mechanism and model of nano-iron/carbon were also discussed.Although nano-iron/carbon composite can be obtained from the direct carbonization of ferrocene at 420℃, it can not exist in air and easily react with oxygen due to the unstability of the naked nano-iron particles in air. From the co-carbonization of ferrocene and naphthalene the nano-iron/carbon material was prepared, in which the diameter of the iron particle dispersed in carbon matrix uniformly is about 20~60nm.The addition of ferrocene accelerated the reaction velocity of petroleum residue condensation and increased the pyridine insoluble fraction yield obviously. In the resulting material, the diameter of the iron particle is about 20~50nm. The ultra-fine iron crystal arranges orderly and induce the carbon to encapsulate the nano-iron particle. The matrix carbon is amorphous.Because of the existence of the heteroatoms such as O, S, N etc. in petroleum residue, the nano-composite contains not only the main a -Fe particles but also some amount of Fe3O4and Fe,.xS compounds. After further heat treatment at 700-900 ℃ for 1 hour, the Fe3O4and Fe1-xS disappeared gradually and transformed into a -Fe and austenitic iron.The result of the magnetism test indicated that the nano-iron particle/carbon material have the typical soft magnetism and can be magnetized/demagnetized repeatedly, which may be as the candidate of information record materials.