Single-cell solid oxide fuel cell experiments using thin-film, sputter-deposited Ni pattern anodes microfabricated on single-crystal yttria-stabilized zirconia ͑YSZ͒ electrolyte disks have been performed to examine the electrochemical oxidation of H 2 , CO, and CO/H 2 mixtures. Porous lanthanum strontium manganate ͑LSM͒/YSZ cathodes have been used and characterized in separate symmetric cell experiments such that Ni anode overpotentials and impedances can be isolated. Post-test scanning electron microscopy imaging revealed that at the high temperatures ͑735-850°C͒, the 100-nm thin Ni patterns broke up into interconnected regions resulting in three-phase boundary lengths that roughly correlated with the original coverage area of the pretested dense Ni patterns. Electrochemical characterization for H 2 , CO, and CO/H 2 oxidation under dry and wet ͑ϳ4% H 2 O͒ feeds showed that the interconnected anode overpotentials and polarization resistances correlated with the original Ni pattern area for the various pattern geometries. Higher activation overpotentials and polarization resistances observed for CO in comparison to H 2 were not observed for CO/H 2 mixtures down to 25% H 2 . Results indicated detrimental effects of H 2 O on CO oxidation power densities due to drops in open-circuit voltages without reduction in polarization resistance, and enhancement due to water-gas shift reactions was not seen. Our results provide the basis for insights into H 2 and CO electro-oxidation on Ni/YSZ anodes.High-temperature solid oxide fuel cells ͑SOFCs͒ are being developed to operate on direct feeds of methane, 1-3 larger hydrocarbons fuels, 4 and also oxygenated fuels. 5 The numerous efforts to sustain direct utilization of hydrocarbons in SOFCs have indicated that conventional Ni/yttria-stabilized zirconia ͑YSZ͒ SOFC anodes are prone to uncontrolled carbon deposition under conditions for dry hydrocarbon feeds, particularly for species with multiple carbon atoms. 6 Thus, much research has focused on alternative anode materials, such as Cu/CeO x , 7-9 and alternative operating strategies where either steam 1,3 or O 2 10,11 is added to the anode flow stream. With the addition of steam and or O 2 in a hydrocarbon feed, a porous Ni/YSZ anode matrix can provide catalytic internal reforming and thereby convert some, if not all, of the hydrocarbon to H 2 and CO either through steam reforming or partial oxidation. 8,12 Internal reforming reactions have been shown to work well under some conditions at alleviating carbon deposition in conventional Nibased anode structures. 1,3,13 Internal diffusion of products along the length of a fuel cell will promote some steam reforming even with pure hydrocarbon feeds, but it remains an outstanding question as to whether internal reforming can be sustained such that otherwise unacceptable Ni/YSZ anodes may be viable with some carbonaceous fuels. Reforming of hydrocarbons in SOFCs or even in upstream reactors 14 suggests the importance of electrochemical oxidation of H 2 and CO mixtures 15 for understan...

To eliminate complications associated with gas-phase transport in porous SOFC anodes, microfabricated Ni patterned anodes on YSZ electrolytes have been studied with impedance spectroscopy and voltammetry to evaluate CO electrochemical oxidation under dry and wet conditions. The patterned anodes provide a measure for approximating charge transfer rates per length of three-phase boundary. Adding ~ 3% H 2 O (by mole) to CO/CO 2 anode flows increases exchange current densities by approximately 1.5X for temperatures between 700 and 800 °C. This suggests that water gas shift does create adsorbed H on the Ni electrocatalyst for increased charge transfer rates. However, comparison with H 2 exchange current densities indicates that CO electrochemical oxidation is still the dominant source of Faradaic current. Analysis of the measured impedance spectra for the dry and wet CO/CO 2 anode flows reveals that both high-frequency charge transfer activation and low-frequency adsorption and surface diffusion are contributing significantly to the measured anode overpotentials.

The goal of this work was to present results of mechanical characterization and ballistic investigation of 3-D printed alumina (Al 2 O 3 )-based armor plates, manufactured using two additive manufacturing-based methods: pressurized spray deposition (PSD) and direct ink write (DIW), to determine the maturity of these additive-based processes against the industry standard process. The DIW plates exhibited superior hardness, flexural strength, and density compared to the PSD plates, and in many respects, even eclipsed some of the properties of the commercial isopressed (IP) material. Plates (90 mm × 90 mm × 8 mm) of these composition were manufactured for ballistic analysis in accordance with established ballistic characterization procedures, using a 50.8-mm-thick Aluminum 6061 plate as backing and witness plates in the case of penetration or deformation. Six alumina plates were examined ballisitically (one shot per plate) against the 12.7 mm APM2 projectile (45.9 g) at an impact velocity of 840 m/second. The plates that were manufactured using the DIW method provided a higher impact resistance than the PSD method, however, both did not perform as well as the traditionally processed IP material, due to the presence of defects introduced due to the printing processes. K E Y W O R D S additive manufacturing, alumina, applications, armor, ceramic engineering | 425 JONES Et al. How to cite this article: Jones TL, Vargas-Gonzalez LR, Scott B, Goodman B, Becker B. Ballistic evaluation and damage characterization of 3-D printed, alumina-based ceramics for light armor applications. Int J Appl Ceram Technol. 2020;17:424-437. https ://doi.

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