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- ItemDevelopment of Ni-Sr(V,Ti)O3-δ Fuel Electrodes for Solid Oxide Fuel Cells(Basel : MDPI, 2021) Serôdio Costa, Bernardo F.; Arias-Serrano, Blanca I.; Yaremchenko, Aleksey A.A series of strontium titanates-vanadates (STVN) with nominal cation composition Sr1-xTi1-y-zVyNizO3-δ (x = 0–0.04, y = 0.20–0.40 and z = 0.02–0.12) were prepared by a solid-state reaction route in 10% H2–N2 atmosphere and characterized under reducing conditions as potential fuel electrode materials for solid oxide fuel cells. Detailed phase evolution studies using XRD and SEM/EDS demonstrated that firing at temperatures as high as 1200◦C is required to eliminate undesirable secondary phases. Under such conditions, nickel tends to segregate as a metallic phase and is unlikely to incorporate into the perovskite lattice. Ceramic samples sintered at 1500◦C ex-hibited temperature-activated electrical conductivity that showed a weak p(O2 ) dependence and increased with vanadium content, reaching a maximum of ~17 S/cm at 1000◦C. STVN ceramics showed moderate thermal expansion coefficients (12.5–14.3 ppm/K at 25–1100◦C) compatible with that of yttria-stabilized zirconia (8YSZ). Porous STVN electrodes on 8YSZ solid electrolytes were fabricated at 1100◦C and studied using electrochemical impedance spectroscopy at 700–900◦C in an atmosphere of diluted humidified H2 under zero DC conditions. As-prepared STVN electrodes demonstrated comparatively poor electrochemical performance, which was attributed to insufficient intrinsic electrocatalytic activity and agglomeration of metallic nickel during the high-temperature synthetic procedure. Incorporation of an oxygen-ion-conducting Ce0.9Gd0.1O2-δ phase (20–30 wt.%) and nano-sized Ni as electrocatalyst (≥1 wt.%) into the porous electrode structure via infiltration re-sulted in a substantial improvement in electrochemical activity and reduction of electrode polarization resistance by 6–8 times at 900◦C and ≥ one order of magnitude at 800◦C.
- ItemDevelopment of Liquid Diene Rubber Based Highly Deformable Interactive Fiber-Elastomer Composites(Basel : MDPI, 2022-01-05) Kamble, Vikram G.; Mersch, Johannes; Tahir, Muhammad; Stöckelhuber, Klaus Werner; Das, Amit; Wießner, SvenThe preparation of intelligent structures for multiple smart applications such as soft-ro-botics, artificial limbs, etc., is a rapidly evolving research topic. In the present work, the preparation of a functional fabric, and its integration into a soft elastomeric matrix to develop an adaptive fiber-elastomer composite structure, is presented. Functional fabric, with the implementation of the shape memory effect, was combined with liquid polybutadiene rubber by means of a low-temperature vulcanization process. A detailed investigation on the crosslinking behavior of liquid polybutadiene rubber was performed to develop a rubber formulation that is capable of crosslinking liquid rubber at 75 °C, a temperature that is much lower than the phase transformation temperature of SMA wires (90–110 °C). By utilizing the unique low-temperature crosslinking protocol for liquid polybutadiene rubber, soft intelligent structures containing functional fabric were developed. The adaptive structures were successfully activated by Joule heating. The deformation behavior of the smart structures was experimentally demonstrated by reaching a 120 mm bending distance at an activation voltage of 8 V without an additional load, whereas 90 mm, 70 mm, 65 mm, 57 mm bending distances were achieved with attached weights of 5 g, 10 g, 20 g, 30 g, respectively.