Optimization of Ni-YSZ solid oxide fuel cell anodes by surface laser melting

A cermet composed of a metallic component (nickel) and a ceramic matrix (yttria stabilized zirconia) is commonly used as the anode for solid oxide fuel cells (SOFC). In the present work we intend to improve the performance of Ni-YSZ anodes by surface laser melting. Symmetrical cells, consisting of two NiO-YSZ anodes (similar to 20 pin thickness) separated by a relatively thin YSZ electrolyte (similar to 500 pm) were fabricated by convectional ceramic techniques. Subsequently, laser melting treatments of both anodes were performed using a CO2 laser system, producing a NiO-YSZ eutectic lamellar microstructure. Laser power of 100W and processing rates of 1 mm s(-1) were determined as the optimum processing conditions. Symmetrical processed plates (eutectic sample) were electrically characterized by impedance spectroscopy (EIS), and the results were compared with non-processed plates (ceramic sample). Preliminary EIS results showed that the polarization resistance at higher temperatures (in the range of 900 degrees C) is about 0.5 Omega cm(2) for both the eutectic and the ceramic sample. However, at lower temperatures (in the range of 800 degrees C) the polarization resistance for both samples differs considerably (2.9 and 1.6 Omega cm(2) for the ceramic and eutectic sample, respectively). These experiments confirmed that optimization of the microstructure by laser surface treatment plays a crucial role in the electrochemical properties of the anode cermets. (C) 2015 Elsevier B.V. All rights reserved.