【作者】 王凤华；

【导师】 郭瑞松；

【作者基本信息】 天津大学 ， 材料学， 2004， 硕士

【摘要】 本文对Ni-YSZ阳极材料的制备和性能进行了研究，采用流延法制备了多层阳极支撑复合SOFC阳极基底，为实现SOFC的中温化奠定一定的基础。以NH4HCO3为沉淀剂制备NiO的产率比较高，由Ni氧化制备NiO的工艺比较简单，但是它们所制得Ni-YSZ的电导率却比NH3(H2O的低0.7和1.4个数量级。因此选择NH3(H2O为沉淀剂制备NiO粉末，严格控制溶液的pH值以提高产率。YSZ制备以NH3(H2O为共沉淀剂，pH＝8.2。600℃下煅烧得到了立方ZrO2粉末，平均粒径为20nm左右。采用机械混合法、包裹沉淀法和燃烧合成法制备NiO-YSZ粉末。将NiO和YSZ粉末用无水乙醇球磨48h得到混合均匀的NiO-YSZ粉末。用包裹沉淀法制备NiO-YSZ粉末时，pH＝8.5～9.0，以NH3(H2O为共沉淀剂。在不同温度下煅烧得到NiO-YSZ粉末。在600℃下NiO-YSZ粉末已经结晶完好，颗粒大小为20nm左右。硝酸盐和柠檬酸氧化还原反应生成的NiO-YSZ粉末粒径为纳米级。柠檬酸/硝酸盐的起始摩尔比c/n小于并接近化学计量比0.54时，试样C（c/n＝0.5）燃烧反应最强烈，由XRD图谱，差热和热重分析得知粉末中有Ni相存在。试样A c/n较小，反应速度慢，又不存在还原气氛，因而没有Ni相生成。测定了不同温度下烧结的NiO-YSZ复合材料和还原后的Ni-YSZ金属陶瓷的密度。考虑烧结温度对性能的影响，确定了最佳烧结制度为1400℃、2h。NiO-YSZ在H2中800℃还原4h得到了Ni-YSZ。显微结构分析结果表明，YSZ相形成了连续的网络结构，Ni相和气孔比较均匀地分布于YSZ的网络结构中。分析Ni-YSZ金属陶瓷电导率的影响因素，结果表明：①随着烧结温度的升高，电导率几乎是线性增加的。1400℃烧结试样的电导率最高，在600℃～800℃，达到103.4S/cm。②不同的制备工艺，NiO粉末的性能不同，导致电导率的差异。③在燃烧合成法中，随着c/n的增大，电导率先增加后降低。在c/n＝0.5时（试样C）最高，达到103.6S/cm。④采用燃烧合成法制备NiO-YSZ粉末所得Ni-YSZ的电导率比机械混合法的和包裹沉淀法的高0.2和0.6个数量级。为了优化阳极的显微结构和提高阳极的性能。采用流延法制备了多层复合阳极膜与电解质膜，共烧结得到了SOFC阳极支撑复合阳极基底。单层的采用Ni/YSZ=55：45的Ni-YSZ金属陶瓷；双层：Ni/YSZ=70：30的金属陶瓷作为界面层，Ni/YSZ=40：60的金属陶瓷作为主体层；三层：第一层为Ni/YSZ=40：60 ，第二层为Ni/YSZ=55：45，第三层为Ni/YSZ=70：30的金属陶瓷。更多还原

【Abstract】 The preparation and properties of Ni-YSZ anode materials were studied in this paper. The multilayer anode-supported composite SOFC anode substrates were prepared by the tape-casting method. The aim of this study is to make the base for reducing the operating temperature.It was shown that the production efficiency of precipitation method using NH4HCO3 as a precipitant was high and the technology of NiO powders prepared by the oxidation of Ni metal was simple. The electrical conductivities of the Ni-YSZ cermet prepared by these two methods were 0.7 and 1.4 orders of magnitude less than that prepared by the precipitation method, using NH3(H2O as precipitant. Thus the precipitation method, using NH3(H2O as precipitant was chosen for preparing NiO powders. In order to raise the production efficiency, the pH value was controlled strictly. YSZ powders were obtained by the co-precipitation method, controlling the pH at 8.2. NH3(H2O was used as co-precipitant. The powder was calcined at 600(C in air for 1h to obtain the YSZ powder with the average particle size around 20nm. NiO-YSZ powders were prepared by the mechanical mixing method, coating precipitation method and the combustion synthesis method respectively. In the first route, NiO and YSZ were ball-milled in alcohol for 48h to obtain the homogeneous powders. The NiO-YSZ powders, which were prepared by the coating precipitation method, were calcined at 600(C and 800(C. NH3(H2O was used as co-precipitant, controlling the pH at 8.5~9.0. It is obvious that the two phases were well crystallized at 600℃. The particle size of the powder is about 20nm. Redox combustion reaction between metal nitrate and citric acid yielded ultrafine NiO-YSZ powders. When the c/n initial molar ratio was less than and close to the stoichiometric value 0.54, the combustion progressing of Sample C (c/n＝0.5) was the most intensive. Through the XRD patterns and TG and DSC analysis of synthesized sample C powder, the Ni phase was discovered. Because the c/n initial molar ratio of Sample A is minor, the combustion progress was slow. Also there was no reducing atmosphere. Ni phase was not discovered in Sample A.The density of the NiO-YSZ composite sintered at different temperatures and Ni-YSZ cermet was measured via the Archimedes method. Considering the influence of the sintering temperature on the anode material performance, the rational sintering <WP=4>system was 1400(C for 2h. The sintered NiO-YSZ composite was reduced at 800(C in H2 atmosphere for 4h into Ni-YSZ cermet entirely. The microstructure of the samples was investigated. The YSZ phases formed a continuous network while the Ni particles and pores were uniformly dispersed in the network.The influencing factors on the electrical conductivity of the Ni-YSZ cermet were considered. It was found that: 1) the electrical conductivity increased nearly linear with the elevation of the sintering temperature. The electrical conductivity reached above 103.4 S/cm for the sample sintered at 1400(C for 2h when testing from 600(C to 800(C. 2) the different technologies resulted in the different properties of the NiO powders, and then resulted in the difference of the electrical conductivity. 3) The electrical conductivity increased firstly then decreased with the c/n increasing during the combustion synthesis. The electrical conductivity of Sample C, whose c/n was 0.5, reached above 103.6 S/cm. 4) The electrical conductivity of the Ni-YSZ cermet prepared by the combustion synthesis method was 0.2 and 0.6 order of magnitude higher than that prepared by the mechanical mixing method and the coating precipitation method respectively.In order to optimize the anode microstructure and improve the anode performances, the multilayer composite anode films and the electrolyte films were prepared by the tape-casting method. The anode-supported composite SOFC anode substrates were obtained by co-sintering. The single layer anodes used the Ni/YSZ=55: 45 cermet. The double layer anodes consist of the interfacial layer and bulk layer. As the interfacial layer,更多还原