Research On Preparation Of Ferric/Nickel Base Nano-scale Powders By Solution Combustion Synthesis

In the mid80s20th century, nanomaterials with novel microstructure were developed and have already become an important field of nanoscience now. Fe/Ni-based nanoparticles exhibit many special physical and chemical properties and have a lot of applications, especially in fields of catalyst and magnetic material. In this thesis, the solution combustion synthesis of Fe/Ni nanoparticles was investigated in details, and the main results are listed as followed:The solution combustion mechanisms of the nickel nitrate systems with different fuels were discussed and calculated in thermodynamic ways. The results showed that adiabatic temperature in the system increased with the ratio of fuel and nickel nitrate increasing. The NiO nanoparticles were synthesized via solution combustion using urea, glucose and glycine as fuels, and nickel nitrate as nickel source. The experimental results were consisted with the thermodynamic calculation results. When urea was added, the combustion proceeded vigorously, which resulted in the failure of the control of product. When glucose was adapted as fuel, the reaction temperature was too low and the intermediate still existed in the final product. The NiO nanoparticles prepared from glycine have high surface area and small crystalline size.Nanocrystalline Fe-50%Ni and Fe-50%Co powders were synthesized via solution combustion process followed by hydrogen reduction by using nitrates-glycine combustion system. The influence of glycine to nitrates ratios on the combustion behavior and morphology evolution of the combusted powders were investigated. Nano-scale magnetic Fe-50%Ni and Fe-50%Co powders were obtained after combusted powders reduced in hydrogen atmosphere. The effect of reduction temperature on the BET, morphology and crystallite size of the obtained nano-scale magnetic powders was characterized. The Fe-50%Ni powder reduced at700℃has the maximum saturation magnetization and the minimum coercivity values of156.33emu/g and37.2Oe, respectively. The Fe-50%Co powder reduced at800℃exhibited the maximum saturation magnetization of223emu/g and the minimum coercivity of33.2Oe.Ni-Y2O3nanocomposite powder with uniform distribution of fine oxide particles in the metal matrix was successfully fabricated via solution combustion followed by hydrogen reduction by using glucose, nickel nitrate and yttrium nitrate as raw materials. The influence of urea to nickel nitrate ratio on the combustion behavior and morphology evolution of the combusted powder was investigated. The effect of reduction temperature on the BET, morphology and crystallite size of the obtained Ni-Y2O3nanocomposite powder was characterized. The HRTEM image of Ni-Y2O3nanocomposite powder indicated that nano-sized cubic-Y2O3particles with average particle size of about5-10nm were homogeneously dispersed in the nickel matrix. The TEM image of SPS specimen indicated that nano-sized Y2O3particles with the particle size of about5-20nm were homogeneously dispersed in the nickel matrix.Ni-Y2O3nanocomposite powder was compacted in mold and then sintered at atmospheric pressure. The influence of sintering temperature on densification process of Ni-Y2O3nanocomposite powder was studied. The Ni-Y2O3nanocomposite powder was mixed with K491master alloy powder, and densified via hot pressure sintering. The influence of sintering temperature on the microstructure and hardness of samples was investigated.The results showed that the K491alloy reinforced by dispersed Y2O3particles became compact after sintering at1100℃-1250℃for2hours. The hardness increased with the sintering temperature increasing. The sample sintered at1250℃for2hours had the harness of HRC70.5.