Papers by Keyword: NiO-YSZ

Abstract: Ni-YSZ cermet remains to be the most used anode material for solid oxide fuel cells (SOFCs), and metal-supported solid oxide fuel cells are considered as the third generation SOFCs which can possibly address the overpotential and ohmic losses due to thicker components of electrolyte-and anode-supported cells. This study investigates the low-temperature deposition of crystalline NiO-YSZ thin film anodic layers on stainless steel (SS316L) substrates via screen-printing and hot pressing. Results revealed that screen-printing and hot pressing of NiO-YSZ on SS316L substrates at only 700°C (100 MPa) successfully deposited a ~40-μm thin film with a cubic crystalline structure. The thin film can also be fully reduced to Ni-YSZ with a cubic crystalline structure for both Ni and YSZ. In addition, EDS mapping revealed a relatively homogenous distribution of the Ni-YSZ components.

Abstract: Nickel and yttria-stabilized zirconia (Ni-YSZ) ceramic-metal composite electrodes are commonly used for solid oxide electrochemical cells because of their good ionic and electronic conductivity. In this study, a thin film of NiO-YSZ was prepared via screen-print method and subsequently reduced to Ni-YSZ. The precursor powder for screen-printing was prepared via glycine-nitrate combustion process. The effect of precursor particle size and of the use of PVP as binder on film uniformity and quality were investigated. For the NiO-YSZ film, scanning electron microscopy (SEM) micrographs and X-ray diffraction (XRD) patterns confirmed that size reduction and the use of binder both improved the quality and uniformity of the deposit without changing the composition of the sintered film. SEM with energy-dispersive spectroscopy (EDS) showed elemental mapping of unreduced and reduced films, revealing micro grain size faceted particles of NiO and Ni, while smooth and much larger YSZ grains were also observed. XRD of reduced Ni-YSZ film revealed that the NiO peaks had been replaced by Ni.

Abstract: The physical properties and microstructures of supporting anodes are crucial for the performances of the entire SOFCs. In this investigation, the rape pollen was developed as a novel pore-former to improve the properties of the conventional NiO–YSZ(yttria-stabilized zirconia) anode substrate of solid oxide fuel cell. The advantage of using this pore-former over the conventional ones (e.g. polymethyl methacrylate (PMMA), carbon and flour) is that this pore-former had high porosity、global pore shape and uniform pore size distribution in the anode substrates, which are beneficial for rapid transport of the fuel and byproduct. The microstructure was observed by SEM, and the porosity of anode was measured by Archimedes method. The results showed that the optimum weight percent concentration was 15%, correspondingly, porosity was 40.3%, which was suitable for supporting anodes for SOFC application. And the open-circuit voltage (OCV) as high as 1.058V was obtained ,and the maximum power densities of 0.794W/cm² was achieved at 750°C, respectively, using hydrogen as fuel and ambient air as oxidant.

Abstract: To explain the deformation during the co-sintering of NiO/YSZ-YSZ coating, the sintering shrinkage of NiO, NiO/YSZ and YSZ were measured by dilatometer. The coefficient of deformation variable (CDV, α) is defined to describe the difference of the sintering behaviors between the layers constrained.

Abstract: The arrangement of ceramic layers in laminated structures is an interesting way to enhance the flaw tolerance of brittle ceramic materials. The interfaces are expected to deflect cracks, increasing the fracture energy of the laminate compared to a monolithic material and thus raising the toughness. The target of this study is to predict the volume fraction of pores, in porous layers, required to cause crack deflection. Formulation of the fracture toughness and fracture energy as function of the material porosity is presented for random and ordered pores distribution. The effect of crack tip-flaws interaction is considered to estimate the pores volume fraction needed for crack deflection. In this work, dense and porous layers of NiO-YSZ material similar to the one used in the fuel cells technology are considered. The fracture energy of a porous material with an ordered distribution of pores shows a possibility of crack deflection at a porosity of 22.5%. However for a system with randomly distributed pores this possibility can be seen at 36% of porosity.