Thin film YSZ coatings on functionally graded freeze cast NiO/YSZ SOFC anode supports

Abstract

Intermediate temperature (600-800°C) solid oxide fuel cell (SOFC) technology is often limited by inadequate gas transport in electrodes, and high ion transport resistance electrolytes. In this study, large area filtered arc deposition (LAFAD) and hybrid filtered arc-assisted e-beam physical vapor deposition (FA-EBPVD) technologies, in combination with freeze-tape-casting, were used to fabricate SOFC anode/electrolyte bi-layers with functionally graded porous anode microstructures and thin film electrolytes favorable for both gas transport and low resistance. Traditionally-processed NiO/YSZ in addition to freeze-tape-cast NiO/YSZ anode substrates were fabricated and subsequently coated with thin film (\1-20 lm) YSZ via LAFAD and FA-EBPVD. LAFAD was found to be effective in applying thin (*1 lm) dense YSZ films on porous substrates at *400°C. FA-EBPVD produced relatively thick (*10-20 lm) dense YSZ coatings on porous substrates, with columnar morphology and nano-metrical grain size. A *10 lm FA-EBPVD YSZ coating was observed to bridge NiO/YSZ surface pores of *10 lm, which typically requires pre-filling prior to conventional thin film coating processes. Coated substrates exhibited negligible curvature, yielding flat anode/electrode bi-layers up to 2.5 cm in diameter. These results are presented with conderations for future SOFC development discussed.

Influence of the Index Metallic Salts - Complexing Agent in a Sol-Gel Process to Obtain Nanoscaled Zirconium Substituted Yttrium (Ysz) to Electrolyte Application in Solid Oxide Fuel Cell (Sofc)

“…The YSZ grain dimension was calculated with a mean 50 nm and standard deviation close at 9 nm, other research work as reference 8 report for a calcination near to 1000 °C, with sol-gel technique a size between 30 and 40 nm, but they do not say their heating speed, neither their time inside the four, the reference 10 reported for YSZ thin film with laser technique a grain size 21.4± 1.4 nm. This YSZ material in their commercial manner (TZ8YS, Tosoh) has reported between 20 and 30 nm [1,11]. The grain size of this study by image analysis is close to the reported values and the YSZ commercial powder is possible that it will be grinding in order to get a more little grain size.…”

Dispersion, connectivity and tortuosity of hierarchical porosity composite SOFC cathodes prepared by freeze-casting

“…14 The LSM and YSZ powders were first ballmilled dry to form a homogenous powder. This mixture was slowly added into deionized (DI) water containing an ammonium polymethacrylate dispersant (Darvan C-N, R.T. Vanderbilt Co., Norwalk, CT) until approximately 25 vol.% solids was reached.…”

Freeze‐cast yttria‐stabilized zirconia pore networks: Effects of alcohol additives

“…The large number density of ceramic bridges and secondary pores within the alcohol samples believed to result from interactions between alcohols, particularly methanol, may be extremely beneficial in increasing TPB area, but, especially within the methanol sample which had increased tortuosity along the freezing direction, they may hinder gas flow compared to the pore structure of the control sample. 20 Other methods of increasing TPB area without significantly increasing tortuosity include incorporating a second sacrificial phase or by partial sintering to achieve submicron porosity, as it is not achievable in freeze-cast structures. 37,43 Alternatively, SOFCs can be improved by modifying the electrode pore surface through infiltration of particles.…”