| Great attention has been paid on Solid Oxide Fuel Cell(SOFC) for the advantages of high efficiency,clean, and safety.The low operating temperature of reaction is the key to bring SOFC into our dailylife.The Sm2O3 doped CeO2 (Ce0.8Sm0.2O1.9) system is the electrolyte with excellent performance at intermediate-to-low temperature.It exhibits 10 times oxide ion conductivity higher than yttria stabilized zirconia(YSZ) under 800℃. Therefore, Ni/Ce0.8Sm0.2O1.9 (Ni/SDC) is a potential material for the anode of the SOFC.The anode are usually synthesized by solid-state reaction ,co-precipitation and sol-gel methods.These methods have some deficiency.In recent years, with the development of lower-temperature synthetic technique, the scientists searching for a way to unite the sol-gel and self propagation high temperature synthesis(SHS) to prepare high sintering activity,dispersed powders and keep both of their merits developed a new chemosynthesis---citric acid-nitrate combustion method.NiO/Ce0.8Sm0.2O1.9(NiO/SDC) which were synthesized by citric acid-nitrate combustion method can reduce the resistance of crystal boundry and get nanocrystalline with high activity and porosity. However,because of the little particle size, high specific area ,high surface energy and instability , the Nano-powders agglomerate into second particle easily whose particle size growing up. Then Nano-powders losing their characteristic impact the synthesis of NiO/SDC and the performance of SOFC.This task adopts improved citric acid-nitrate combustion method to solve agglomeration of NiO/SDC which has positive meaning on non-agglomerate nano-powders.Study is made about the effects of different molar ratios of citric acid to metal ions(MRCM) on the particle size and agglomeration of NiO/SDC powders in this thesis.The value of MRCM adopted 1.0,1.5 and 2.0, respectively. The XRD data indicate that the powders have smallest crystallite size than the others'when the MRCM=1.0. The crystallite size of NiO is 7.1nm, SDC is 5.04nm. NiO/SDC powders were synthesized when MRCM=1.15, DTA -TG results show that the decomposition process of dried gel can be nearly finished below 360℃. XRD shows there hasn't the peak of Sm2O3 in ignited powders.The Sm3+ had joined in fluorite structure of CeO2 .The specific surface area of ignited powders is biggest, achieved 29.508 m2/g,the powders calcined at 800℃is 6.298 m2/g .Because of crystallite grow up with increasing calcination temperature,the specific surface area of powders decreased. Because of the little particle size and high surface activity ,it can be seen clearly from TEM that the powders are nearly ideal spherical in shape and exhibit a narrow distribution in sizes .Ni/SDC cermet were synthesized by citric acid-nitrate combustion method. The structure, morphology ,sinter performance and conductivity had been observed: The reduced Ni/SDC metal cermets with porosity of about 20-50% can satisfy the diffusion of fuel gas and water.According to sintered shrinkage curves and technical thermal expansion coefficientsγ,NiO/SDC with NiO content from 45 to 55 wet.% has matched well with SDC electrolyte in the thermal expansion. The conductivities increase accordingly with Ni content and calcination temperature ,but decrease with testing temperature.Using different dispersants in the precursors to solve the agglomeration of NiO/SDC powders,and compared their effects in this thesis: Particulate properties shows that NiO/SDC powders prepared with dispersants in the precursors have obvious effects on reduction of agglomeration,the second agglomeration is inhibited.The NiO/SDC powders prepared with PEG6000 in the precursors have the best dispersion effects. Triethyl phosphate and polyvinyl alcohol 124 take the second place. The NiO/SDC powders prepared with PEG6000 have the least average particle size, maximal surface area and least surface area average particle size,the values are 1.758μm, 6.44m2/g and 0.932μm respectively.
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