The Research On Preparation, Intercalation Process And Reduction Technics Of FeCl₃-NiCl₂-GICs

Ternary FeCl₃-NiCl₂-GICs was synthesized by molten salts method in quantitative air. The natural flake graphite was used as host material and the mixture of NiCl₂ and FeCl₃ was as intercalant. The effects of graphite granularity, mole ratio of FeCl₃ to NiCl₂, reaction temperature and reaction time on the stage structure,the Ni content and its distribution of the products were studied with four established criterions reflecting the intercalation reaction process by the orthogonal experimental method. When the graphite granularity is 325 mesh, the reaction time is 24hr , the reaction temperature is 450℃and the molar ratio of FeCl₃ to NiCl₂ is 9:3(the molar ratio of carbon to metal chlorides is 3:1), the optimal stage 1 ternary FeCl₃-NiCl₂-GICs can be obtained.And when the graphite granularity is 500 mesh, the reaction time is 24hr , the reaction temperature is 400℃and the molar ratio of FeCl₃ to NiCl₂ is 7:3(the molar ratio of carbon to metal chlorides is 6:1), the optimal stage 2 ternary FeCl₃-NiCl₂-GICs can be obtained. The low-volume container of non-rust steel to prepare ternary FeCl₃-NiCl₂-GICs was self-designed and made.The intercalation process of FeCl₃-NiCl₂-GICs was studied using two synthesization technics by XRD, SEM, EDS and Raman. The result shows its intercalation process is made of five stages. The first is the forming, adsorption, and intercalation of intercalant.And then is the forming and improving of the stage structure. And the forming process of the stage structure can be separated to three parts. Forming FeCl₃-GICs is the first. And then NiCl₂ intercalates into FeCl₃-GICs to form FeCl₃-NiCl₂-GICs. The last is the improvement of the stage structure and the increasement of its crystal particles.The speed of intercalation process is decided greatly by the diffuse of Ni.The intercalation fashions of NiCl₂ are mostly embedding and melting together with FeCl₃ to NiFe2Cl8. But the intercalation amount of Ni by embedding is about 64% of the general content, much more than the amount by the other fashion.FeCl₃-NiCl₂-GICs were reduced by H2, hydrazine hydrate,Na and NaBH4. And the reduction effects of above reducers were studied by XRD,SEM and EDS. The result shows the reduction effect of H2 is the best. It was studied that the influence of reduction temperature and time on the stage structure and n(C)/(n(Fe)+n(Ni)). The Cl content in the reduction product was decreased with reduction temperature and time increasing. To improve the reduction effect of FeCl₃-NiCl₂-GICs by H2, the air was introduced to the reactor during the cooling period after reduction. The proportion of Cl in the reduction product was decreased to 10.71% using the method.The reason why FeCl₃-NiCl₂-GICs cannot be reduced thoroughly was that FeCl₃ can't be reduced totally to Fe,just FeCl2.When FeCl₃-NiCl₂-GICs was reduced by H2, the FeNi alloy was generated, amount of FeNi alloy concentrate nearby the edge of graphite layer, and few is located in the graphite layer.The microwave absorption properties of graphite, FeCl₃-NiCl₂-GICs,FeNi/graphite nano-composite material and Fe2O3/graphite composite material were tested. The results show that microwave absorption property of Fe2O3/graphite was the best of all. The maximum theoretical reflection loss of Fe2O3/graphite composite material is about -10dB. FeNi/graphite nanocomposite material and Fe2O3/graphite composite material will be prospective to become new microwave absorption material.