固体氧化物燃料电池阳极材料的流延制备和电池性能研究

利用流延法制备NiO-YSZ阳极，采用磁控溅射、多层流延法制备YSZ电解质薄膜，丝网印刷制备BSCF-YSZ阴极，制备出Ni-YSZ／YSZ／BSCF-YSZ单电池。阳极制备中探索了浆料配比对生坯性能的影响；研究了不同造孔剂得到的流延阳极的微结构形貌差异。考察了双层流延、磁控溅射制备YSZ薄膜的微观结构，并测试评价了电池性能。     

燃料电池YSZ薄膜凝胶-流延成型的制备研究

结合流延法和凝胶法的优点,形成了水溶液丙烯酰胺体系的凝胶－流延成型方法。以固相含量为５４ｖｏｌ％的ＹＳＺ 体为浆料,利用此方法制备了厚度小、致密度高、气孔少的固体电解质ＺｒＯ２薄片,并从粉体特性、分散剂和ｐＨ值对悬浮体性能的影响、素坯及烧结体密度等多角度探讨了工艺的特点。研究表明与干压法、流延法相比,用凝胶－流延成型的薄片成型的薄片致密度高,气孔少、适合制备固体电解质ＹＳＺ薄膜。     

VO_x-Cu浸渍复合阳极支撑的抗硫中温固体氧化物燃料电池的制备与性能

用流延法制备钇稳定氧化锆(YSZ)多孔体素坯,在流延素坯上丝网印刷沉积10Sc1CeSZ电解质,经共烧结得到多孔YSZ支撑致密10Sc1CeSZ薄膜电解质的约为5cm×5cm较大面积的双层膜。在电解质薄膜上依次印刷阻挡层Ce0.8Gd0.2O2(CGO)和阴极La0.6Sr0.4CoO3(LSC)。向多孔YSZ支撑体内浸渍偏钒酸铵、草酸的混合溶液和硝酸铜溶液多次后经低温煅烧后得到V2O5-CuO-YSZ复合阳极。用SEM对双层薄膜结构浸渍前后进行显微结构表征,结果表明流延法制备的多孔YSZ孔洞连通,丝网印刷制备的电解质层致密,电解质厚度约为7μm;浸渍后,催化剂均匀地分布在YSZ孔隙间。在800℃,分别以湿H2和含5.2×10-3体积分数的H2S湿合成气(40%H2,60%CO)为燃料进行电化学测试,开路电压分别为1.07和1.08V,最大功率密度均为37mW/cm2。电性能测试结果表明,该方法制备的固体氧化物燃料电池复合阳极具有抗硫化氢毒化和抗碳沉积的性能。     

添加剂在水基凝胶流延成型中的作用

为制备固相含量高、适合流延工艺的氧化铝陶瓷悬浮体,并保证成型坯片具有良好的强韧性能,通过分析陶瓷悬浮体的粘度、Zeta电位、接触角等参数,研究了各种添加剂对凝胶流延工艺的影响.实验结果表明:分散剂可提高悬浮体的Zeta电位,从而提高固相体积含量;增塑剂可明显提高坯片的柔韧性;表面活性剂可大幅度降低悬浮体与基带的接触角(从93°降低到72.2°).成功制备出固相含量超过50%的悬浮体,成型后的坯片表面平整,强度高,柔韧性好.     

水基流延工艺制备β"-Al2O3固体电解质薄膜的研究

采用溶胶-凝胶法制备了β″-Al2O3前驱体粉体,将该前驱体在850℃焙烧1h的产物作为水基流延浆料的陶瓷粉体,以去离子水为溶剂,加入适量的S464表面活性剂、WB4101粘结剂和PL005增塑剂,采用水基流延工艺成功制备了表面光滑、颗粒分布均匀的β″-Al2O3固体电解质前驱体薄膜.研究结果表明:β″-Al2O3前驱体水基流延薄膜经等静压成型并在1500℃高温烧结后,便可获得薄膜型β″-Al2O3固体电解质(JCPDS卡片号:19-1173).     

8YSZ陶瓷成型与烧结工艺的优化

为了改善8YSZ陶瓷的力学性能,以8YSZ双粒度粉体为研究对象,对其进行干压成型、无压烧结实验。对成型压力、保压时间及黏结剂用量等成型工艺参数进行了优化;利用正交实验对烧结方案进行了设计,讨论了烧结温度、升温速率、保温时间、烧结方式等烧结工艺参数对8YSZ陶瓷烧结性能和力学性能的影响,并优化出其烧结工艺参数。结果表明:选取PVA加入量10%(质量分数)、成型压力10MPa、保压时间30s的成型工艺参数,可压制出相对密度为54.9%的陶瓷坯体;选取烧结温度1500℃,保温时间4h,升温速率5℃/min,烧结方式裸烧的烧结工艺参数,可制备出相对密度为98.3%,抗弯强度为100.3MPa的8YSZ陶瓷。     

水基凝胶流延法制备SOEC氢电极的研究

采用陶瓷水基凝胶流延方法制备出了固体氧化物电解电池(SOEC)的氢电极.首先研究了分散剂的不同用量和不同固相含量对NiO/YSZ浆料的流变学特性的影响,确定了最佳原料配比.通过测试坯体的热失重曲线确定了氢电极的排胶工艺,并通过烧结实验确定了合理的烧结制度.最终获得了平整、大小可控、性能良好的氢电极,并通过扫描电镜观察了SOEC氢电极的显微结构.     

YSZ流延片的等静压工艺研究

氧化钇稳定氧化锆(YSZ)流延片广泛应用于生产陶瓷传感器,但是流延素坯结构疏松、密度较低,严重影响产品强度。研究了等静压工艺对YSZ流延素坯的影响,通过测试密度、抗弯强度和观察微观结构得出,温等静压工艺更适合YSZ流延片的处理,并找出了最佳工艺参数。     

泥浆喷涂制备阳极支撑YSZ电解质薄膜工艺研究

采用泥浆喷涂工艺制备SOFC用阳极支撑YSZ电解质薄膜,首先采用模压成型工艺制窷iO-YSZ阳北极基底,通过优化泥浆制备工艺条件及喷涂条件,在NiO-YSZ阳极基底上喷涂均匀平整的YSZ电解质涂层,进一步采用共烧结工艺使YSZ电解质层致密.通过在基底中添加碳粉造孔剂,调节阳极基底的烧结收缩率与电解质层烧结收缩率一致,避免电解质涂层的开裂和变形.阳极基底中加入5wt%含量的碳粉,阳极与电解质层烧结收缩率一致.扫描电子显微镜观察电解质涂层表面形貌表明,球磨24h的泥浆喷涂的YSZ涂层较好,阳极基底与电解质膜在1400℃烧结2h,电解质膜层致密,表明通过泥浆喷涂工艺可以制备出致密电解质层.     

改进注浆法制备YSZ电解质薄管的烧结和电性能

用改进注浆法制备出8mol%钇稳定化氧化锆（YSZ）电解质长薄管，研究了YSZ电解质长薄管的烧结工艺，分析了烧结过程和Al2O3掺入量对其致密性的影响，确定了相应的烧结制度，并对所获得的YSZ电解质薄管的电性能进行了研究。研究结果表明：升温速度对YSZ长薄管的性能有着重要影响，坯体中阿拉伯树胶在600℃时被完全烧尽，1400～1500℃的温度范围是烧结的重要阶段，这期间气孔率显著下降，致密性明显提高。加入适量的Al2O3有助于提高YSZ长薄管的致密性。样品的氧离子电导率随烧结密度的增大而提高。利用改进注浆法和上述烧结工艺在1650℃已烧制出相对密度为96.7%、长度为266mm、厚度为0.4～0.9mm的YSZ电解质长薄管。     

热震对ZrO2陶瓷弯曲强度和显微结构的影响

研究了6YSZ、(6Y-Mg)-ZrO2和6YSZ-MgAl2O4复相材料热震处理对力学性能和微观结构的影响.通过XRD和SEM对材料物相和结构的表征,阐明了6YSZ陶瓷在热处理后断裂特性突变的机理.实验结果表明,ZrO2陶瓷在1200～1400℃高温热震处理后,由于热韧化和马氏体相变会出现重烧结,使材料弯曲强度热增大;ZrO2与少量不共溶MgAl2O4形成的复相材料在高温热震处理后会出现明显的热失配现象,使材料的力学性能下降.     

多元掺杂8YSZ电解质性能的研究

利用高温熔融-水淬-球磨法制备TiO2-SrO水冷粉体.将该粉体引入8YSZ陶瓷基体中,研究其对材料致密化、相组成、显微结构、力学性能及电学性能的影响.结果表明,引入TiO2-SrO后,材料的烧结机理为液相烧结,有利于致密化.引入量较少(1%(质量分数))时可不同程度地提高8YSZ的抗弯强度与电导率,因此可以成为较好的SOFC电解质材料.     

热处理温度对磁控溅射法制备YSZ电解质薄膜性能的影响

采用射频磁控溅射方法在NiO-YSZ阳极基底上制备了致密的YSZ电解质薄膜,主要研究了热处理温度对电解质薄膜性能的影响.试验发现随着热处理温度的提高,所制备的YSZ薄膜中晶粒结合更加致密,气孔率显著降低,薄膜与基底间的结合更加紧密.通过组装单体电池实际考察了薄膜的性能,发现随着热处理温度的提高,电池的开路电压及放电性能均有大幅度的提高.在800℃下,开路电压由0.82V提高到1.023V,已接近SOFC的理论电压;最大功率密度由480mW/cm2提高到760 mW/cm2.     

热障涂层材料的研究进展

热障涂层技术广泛用于航空涡轮发动机等尖端领域,相关的研究涉及新型热障涂层材料的开发、粘结层成分和表面结构的优化、高温氧化后热生长氧化物(TGO)或TGO/粘结层(BC)界面处残余应力水平的检测、新型涂层制备工艺的开发等诸多方面.主要阐述了时7-8YSZ热障涂层材料的改良、烧绿石结构材料的开发、超音速微粒轰击粘结层表面细...     

应用电泳沉积法制备固体电解质（8YSZ）薄膜

应用电泳沉积法制备钇稳定二氧化锆（8YSZ）薄膜，探索了影响电泳沉积层密度、厚度、粘附性和形貌的诸多因素，确定的最佳工艺操作条件是粉末浓度为100g／1。电场强度为30V／cm，沉积时间为30s。轻微搅拌或不搅拌。经重复电泳沉积-烧结，获得厚为26～56μm，硬度为4．33GPa，在1000℃时O2-电导率为12．2S／m和O2-电导激活能为1．09eV／mol的薄膜。     

Fracture toughness KIC analysis of Co-doped 7YSZ

Abstract

Co-doped samples of 7YSZ with Yb³⁺, Ce⁴⁺ and Nb⁵⁺ having high porosity are subject to Vickers hardness testing. Fracture toughness K_IC values are obtained by measuring linear and non-linear crack geometries. Three separate means are used to calculate the fracture toughness and to investigate the associated trends. It is confirmed that high amounts of retained tetragonal zirconia improve fracture toughness, while elevated amounts of monoclinic zirconia lower overall fracture toughness. The experimental trend for increasing K_IC is Nb:7YSZ<Yb:7YSZ<7YSZ<Ce:7YSZ; however, this trend is qualitative as the Young’s modulus values for different samples are corrected for porosity using an equation that does not generally apply to indentation techniques.     

Role of dispersion conditions on grindability of yttria stabilized zirconia (YSZ) powders

A precursor for zirconia - 8 mole% yttria (YSZ-ZrO₂-8 m% Y₂O₃) powder was prepared by coprecipitation and the calcination temperature was fixed as 900°C from TG-DTA and XRD studies. The calcined powder could be dry ground only to a mean particle size (D₅₀) of 6 Μm containing substantial amount of coarse agglomerates in the size range 10–100 Μm. The dispersion conditions for its wet grinding were evaluated through zeta-potential and viscosity studies. The zeta-potential variation with pH of the aqueous suspensions of the powder exhibited maximum numerical values at 3 and 11 pH, exhibiting the ideal pHs for dispersion stability through electrostatic columbic repulsion mechanism. Slurries of dry ground powders with solid concentration in the range 15–30 vol.% exhibited pseudo-plastic flow characteristics, indicating presence of flocculates. With progress of grinding, the increase in viscosity of the slurries became less significant with decreasing solid concentration. Even though the particle size of the ground slurries decreased with decreasing solid content, there was little change in it for slurries with solid content < 20 vol.%. Grinding conditions for formation of sinter-active powders of YSZ with sub-micron size (D ₅₀ ∼ 0.7 Μm free of agglomerates of size > 5 Μm) were established. Compacts from this powder could be sintered at 1400°C to translucent bodies with 99% theoretical density.     

Gd2O3掺杂ZrO2基电解质材料的电导率研究

用无机溶胶-凝胶法制备出纳米晶ZrO2基粉体，比较了10GdSZ，5％Gd-8YSZ，8YSZ三种电解质材料，得出在相同工作温度下GdSZ材料有着较高的电导率和较好的材料物理性能。GdSZ材料在未来的实际生产应用中有着广阔的应用前景。     

Study of YSZ-based electrochemical sensors with oxide electrodes for high temperature applications

Potentiometric sensors based on yttria stabilized zirconia (YSZ) with WO₃ as sensing electrode were fabricated using either Pt or Au electrodes. The sensors were studied in the temperature range 550–700°C in the presence of different concentrations (300-1000 ppm) of NO₂ and CO in air. The response to NO₂ was very stable with fast response time (20-40 s). The best sensitivity (18.8 mV/decade) using Pt electrodes was observed at 600°C. At the same temperature a cross-sensitivity (-15 mV/decade) to CO gas was also noticed. The response to CO was decreased (-4 mV/decade) using Au electrode. The role played by WO₃ on the sensing electrode was discussed.     

Morphology and growth of e-beam deposited YSZ thin films

Yttria-stabilized zirconium (YSZ) thin films were grown from the tetragonal phase of ZrO₂ stabilized by 8 wt% of Y₂O₃ (8% of YSZ) ceramic powders using e-beam deposition technique (EB-PVD). The influence of the type of substrate on the microstructure of deposited YSZ thin films was analysed. YSZ thin films (2-3 μm of thickness) were deposited on three different types of substrates: optical quartz (SiO₂), porous Ni-YSZ substrates and Alloy 600 (Fe-Ni-Cr). The dependence of the substrate temperature (from 20 to 600 °C) on the thin film structure and the surface morphology were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that (i) the substrate temperature has an influence on the crystallite size, which varied between 12 and 50 nm, (ii) the substrate type has an influence on the growth mechanism of YSZ thin films, and (iii) a bias voltage applied to the substrate during the deposition of thin films has an influence on the densification of YSZ layers.