【作者】 马小玲；

【导师】 冯小明；

【作者基本信息】 陕西理工学院 ， 材料加工工程， 2011， 硕士

【摘要】 固体氧化物燃料电池是将燃料中的化学能直接转化为电能的一种新型发电装置,具有发电效率高、污染低、安装容易和维护简单等特点。氧化锆基电解质因具有优异的物理、化学性能,在较宽的氧分压范围具有纯的氧离子导电特性,成为制备燃料电池电解质较理想的候选材料。本文用柠檬酸溶胶-凝胶法制备了氧化钇稳定的氧化锆(氧化锆掺量为8mol%,8YSZ)粉体,分别研究了在8YSZ中掺入氧化铁和氧化铋对试样晶体结构、烧结性能和电导率的影响;分别用柠檬酸、聚乙烯醇、乳酸和酒石酸为络合剂,用溶胶-凝胶法制备8YSZ薄膜;选择最佳络合剂,并研究采用此络合剂时,溶胶粘度对薄膜微观结构的影响,研究表明:用柠檬酸溶胶-凝胶法制备的8YSZ前躯体凝胶中,有机物完全分解的温度为500℃;凝胶在500℃预烧1h,试样物相为立方相氧化锆,晶粒大小为6nm左右。将预烧后的粉体压制成型后进行烧结,随着烧结温度升高,试样的致密度增加,在1400℃烧结4h,试样的相对密度可达91.6%。在8YSZ中分别掺入0.5、1.0、1.5和2.0mol%氧化铁和氧化铋,试样的晶体结构均为立方相。掺入氧化铁后,试样的相对密度随掺杂量增加而增加,掺量为2.0mol%试样的相对密度最高,为96.0%;随着掺杂量增加,试样的电导率下降,但掺杂量为0.5、1.0和1.5mol%时,试样的电导率下降较小。掺入氧化铋后,试样的相对密度也随掺杂量增加而增加,掺量为2.0mol%时试样的相对密度最高,为98.2%;在试样中掺杂后,试样的电导率均低于未掺杂试样的电导率;但掺杂量为1.0和1.5mol%时,试样的电导率下降较小。分别用不同络合剂制备8YSZ薄膜时发现,柠檬酸不能作为制备薄膜的络合剂,聚乙烯醇为络合剂制备的薄膜中有较多气孔,乳酸为络合剂制备的薄膜有少量裂纹,酒石酸为络合剂制备的薄膜质量较好。溶胶的粘度对薄膜厚度和微观结构有较大的影响。用酒石酸为络合剂,溶胶粘度分别为65、86和150mPa·s时,制备的薄膜较光滑;但粘度为261mPa·s时,薄膜开始龟裂并从基片上脱落;溶胶粘度大,薄膜的厚度厚,粘度为65mPa·s时,薄膜的厚度为3.8μm左右。更多还原

【Abstract】 Solid oxide fuel cell is a new energy conversion device that produces electricity power by combination of a fuel. It possesses some advantages, such as high energy conversion efficiency, low pollution, easy installation and maintenance. Zirconia is recognized to be the optimal solid electrolyte used for solid oxide fuel cells, because of its good physical and chemic properties, and high ionic conductivity in wide range of oxygen partial pressures.The yttria stabilized zirconia (with an 8mol% of yttria adding, 8YSZ) powder were prepared by sol-gel process using citric acid as chelate agent. The effects of ferric oxide and bismuth oxide on the crystal structure, sintering property and conductivity of 8YSZ were studied, respectively. The effect of different chelate agent on 8YSZ film microstructure were studied, which the film was prepared by sol-gel processes using citric acid, polyvinyl alcohol, lactic acid and tartaric acid as chelate agent, respectively. The effect of sol viscosity on film microstructure was also studied by selecting optimal chelate agent. The results indicated as flowing.The temperature of organics decomposition was 500℃in the precursor, which 8YSZ gel was prepared by citric acid sol-gel processes. The cubical zirconia was obtained by sintering the gel at 500℃for 1h, with about 6nm in crystal size. The density of sample increased while the sintered temperature was raised, which the sample was obtained by pressing pre-sintering powder. The relative density was 91.6% when the sample was sintered at 1400℃for 4h.The crystal structure of sample was cubical zirconia by adding a 0.5, 1.0, 1.5, and 2.0mol% ferric oxide and bismuth oxide in 8YSZ, respectively. The density of sample increased, but the conductivity gradually decreased, while the addition amounts of ferric oxide enhanced. The relative density was 96.0% when the sample was added 2.0mol%ferric oxide. The conductivity decreased less, when an addition of ferric oxide was 0.5, 1.0 and 1.5mol%, respectively. The density of sample increased while the addition amounts of bismuth oxide enhanced. The relative density was 98.2% when the sample was added 2.0mol%bismuth oxide. But the conductivity of added bismuth oxide sample was lower than the sample without adding bismuth oxide. But, the conductivity decreased less, when the addition was 1.0 and 1.5mol%, respectively.The citric acid was not used as chelate agent when the 8YSZ film was prepared by sol-gel method. Some pores were observed in the sample surface that was prepared by using polyvinyl alcohol as chelate agent. A few cracks were observed in the sample surface that was prepared by using lactic acid as chelate agent. But, smooth surface was observed on the sample by using tartaric acid as chelate agent. The thickness and microstructure of film were affected by sol viscosity. The sample was obtained with smooth surface by using the sol with a tartaric acid as chelate agent, 65, 86, and 150mPa·s in viscosity, respectively. But a full of cracks were observed on sample surface and some film fell from substrate when the sol viscosity was 261mPa·s under same conditain. The thickness of film increased when the sol viscosity enhanced. The film was obtained with 3.8μm in thickness when the sol was 65mPa·s in viscosity.更多还原