The electrochemical activity of the metallic-ceramic composite (Cermet) Ni/Zr0,85Y0,15O0,93 (Ni/YSZ) used as anode in stacks of solid oxide fuel cell (SOFC) is controlled by the intrinsic conductivity of its phases, by the available paths for the electric conduction and the diffusion of the fuel gas. These properties are highly influenced by microstructural parameters such as space distribution of the phases, forms and average size of the particles that constitute the Cermet. In this work, some microstructural parameters of anode phases: Ni, YSZ and pores are determined in tablets of the Cermet Ni/YSZ through the treatment of images acquired with optic microscopy. Relating these parameters with the Quantitative Stereological Theory it was possible to calculate the proximity of the phases. The anodes were prepared from mixtures of NiO powder and YSZ powder at mass ratios of NiO/YSZ: 33/67, 56/44, 75/25 and 82/18 and uniaxial pressed into cylindrical pellets. After sintering, the tablets were reduced to Ni/YSZ in hydrogen atmosphere at 900ºC for 2 hours. The transversal surface of each sample was treated and observed with optical microscopy. The images were analyzed with the software Quantikov to determine the microstructural parameters: intercept linear medium and volumetric fraction of the phases. Using these parameters, the contiguity of each phase present in the Cermet was calculated. To prove the validity of the technique, the values of the microstructural parameters based on the composition of the powders were compared to the values based on the image treatment.
cermet; SOFC; contiguity; anode
