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The influence of NiO on the stabilization and microstructure of yittria (Y2O3)‐stabilized zirconia (ZrO2) (YSZ) is examined. Cold‐pressed powders comprising varying amounts of NiO, 8 mol%Y2O3, and ZrO2 were sintered at 1500°C for 4 h. Specimens were subsequently given a 100 h heat treatment at 1500°C. Phase analysis by X‐ray diffraction revealed that the presence of NiO leads to a greater amount of cubic phase ZrO2 for the sintered specimens compared with the control specimens. The cubic ZrO2 lattice parameter was significantly smaller for specimens containing NiO, revealing that Ni2+ ions likely enter the cubic ZrO2 lattice and play a role in decreasing the time and temperature required for stabilization of the cubic phase. A spherical diffusion model was used to estimate the diffusion of Y3+ and Ni2+ into ZrO2. These results are discussed in the context of the role of NiO in the synthesis of YSZ.

Fabrication of defect free co-sintered electrolytes with thickness between 12 μm and 40μm has been demonstrated on planar and tubular cells produced via a spray coating process. Leak testing using a helium leak method showed low diffusional leak rates for cells using optimized spray parameters. The electrolytes were characterized using scanning electron microscopy to qualitatively assess pin holes. Average open circuit voltages (OCVs) of 1080 mV were obtained on tubular cells with spray-coated electrolytes using 3% humidified hydrogen as the fuel. This paper presents spray coating as a viable, cost effective method for electrolyte application in co-fired, anode supported SOFCs.

Manufacturing cost remains one of the major issues facing the solid oxide fuel cell (SOFC) industry. In the anode supported SOFC design, the cermet anode constitutes around 90% of the total material required to build a cell, making the technology very sensitive to anode raw material price. A new patent-pending process called “nickel yttria reaction-sintered zirconia (NiYRSZ)” has been developed for manufacturing SOFC anodes at a fraction of the cost. Typically, the solid component of the anode consists of about 50/50 volume percent nickel and 8 mole percent yttria stabilized zirconia, the latter being a rather costly material. It was discovered that zirconia and yttria powders sintered in the presence of nickel oxide readily form the cubic phase at moderate temperature. Cells manufactured using this process show excellent microstructures for anode supports: a strong bond between the electrolyte and the anode, and a high porosity without addition of pore formers. The strength of the anode was 100 MPa making the material equivalent or slightly superior to an anode fabricated with the traditional NiO/8YSZ material of similar porosity. The resistivity of the material was measured at 850°C and found to be less than 2 mΩ·cm. Cell performance was also compared to cells manufactured with traditional material. Every indication is that SOFC anodes fabricated with this new method perform as well as anodes made with the conventional material set.