Mechanical Characterisation at Nanometric Scale of a New Design of SOFCs

Abstract

The mechanical stability is an important parameter to gain knowledge in the potential applications of a novel design of electrolyte‐supported SOFC, based on yttria‐stabilised zirconia (YSZ) and NiO‐YSZ composites, with cross‐linked channels (∼90 μm of diameter). In this experimental work, the mechanical properties (hardness, H and Young's modulus, E) at different applied loads have been studied using the nanoindentation technique and the equivalent indenter method. On the other hand, the different fracture mechanisms have been determined using atomic force microscopy (AFM), observing the plastic behaviour that takes place during the indentation process. H value for YSZ is higher than that for NiO‐YSZ, while E values for YSZ and NiO‐YSZ are 260 ± 15 and 205 ± 20 GPa, respectively. Only YSZ samples present several radial cracks at the corners nucleated by sharp indentation, thus indicating that H values have been underestimated.

Mechanical properties of highly textured porous Ni–YSZ and Co–YSZ cermets produced from directionally solidified eutectics

“…In any case, measured hardness for YSZ lamellae are in agreement with reported values of 13-20GPa [22,23,24,25] for YSZ bulk samples. However, the H values reported for NiO-YSZ by Roa et al [25] for bulk NiO-YSZ ceramics (6.9-7.5GPa) are lower than the values obtained for NiO lamellae in this manuscript (13.8GPa). This difference could be attributed to the higher density of the eutectics (100 % dense) and also to the lamellar orientation of the component phases.…”

The effect of anode support on the electrochemical performance of microtubular solid oxide fuel cells fabricated by gel-casting

“…For this reason, processing methods are one of the most important topics in microtubular SOFC research, which present several difficulties, such as a relatively high investment in equipment and a long time for the adjustment of processing parameters. The most typical techniques for the support processing include cold isostatic pressing, 14,15 slip-casting, 16,17 extrusion, 18 electrophoretic deposition 19 and co-extrusion 20 amongst others. Alternatively, aqueous gel-casting is a wet-forming technique that allows to prepare dense and porous ceramics, with high quality and complex geometry, in short forming times, and low-cost equipments.…”

Magnetical Response and Mechanical Properties of High Temperature Superconductors, YBaCu3O7-X Materials

“…The indentation load-displacement data were analyzed based on the Hertz equation in the elastic region as follows (Oliver et al, 2004;Field et al, 1993;Field et al, 1995) where h e is the elastic indentation depth. Recently, Barsoum et al (Moseson et al, 2008) proposed the fitting of the stiffness vs. indentation depth data, and extrapolating to zero, as predicated by a relation between E eff and a, as follows (Roa et al, 2010b(Roa et al, , 2010c(Roa et al, , 2011b:…”

“…When catastrophic fracture mechanisms occur, the A(h c ) obtained by this theoretical method is overestimated, and results in an H underestimation. To avoid this problem, the real contact area should be determined using a technique of microscopy (as Scanning Electron Microscopy or Atomic Force Microscopy) and the contact area must be recalculated in order to avoid the sink-in or pile-up effects for brittle and/or ductile materials, respectively (Roa et al, 2009d(Roa et al, , 2010c(Roa et al, , 2011b.…”

“…where E and  are the Elastic modulus and the Poisson's ratio (ν YBa2Cu3O7-x = 0.3 (Roa et al, 2007(Roa et al, , 2009d(Roa et al, , 2010a(Roa et al, , 2010c(Roa et al, , 2011b(Roa et al, , 2011d, respectively. The subindex i denotes the indenter properties (E i = 1141GPa and   ) Pharr et al, 1992).…”