Direct Ceramic Inkjet Printing and Infiltration of Functional Coatings for Metal Supported SOFC

Abstract

Direct Ceramic Inkjet Printing (DCIJP) was applied for fabrication of functional coatings in metal-supported SOFCs. An optimization procedure of the ink formulations and the printing parameters was performed allowing routine production of coatings with thicknesses below 20 µm with an additional benefit of surface defects planarization. Commercial low-cost stainless steel 430L powders were chosen as source materials. The supports sintering procedures was performed in vacuum. The density and open porosity distribution of as-sintered supports were determined by Archimedes' method and optical image analysis. The relation between the sintering conditions and the micro-structural characteristics of the metal supports and the coatings were studied. The influence of the printing parameters on the droplets spreading behaviour was explored. The microstructure and elemental distribution were investigated by Scanning Electron Microscope and energy dispersive X-ray spectrometry system. The analyses confirmed that DCIJP can be successfully applied for the production and modification of metal supported SOFCs.

Inkjet and Aerosol Jet Printing of Electrochemical Devices for Energy Conversion and Storage

“…The accompanying disadvantage is that the high temperature necessitates the use of costly, corrosion resistant interconnects, and introduces issues of materials degradation leading to a lack of system durability. Therefore, inkjet and aerosol jet printing of solid oxide fuel cells has focused on creating geometries which may permit intermediate temperature operation (≈600 °C) by reducing electrolyte thickness and by improving the quality of the electrode/fuel/electrolyte interface . Below, we describe progress in realizing the above mentioned fabrication needs of polymer electrolyte membrane fuel cells and solid oxide fuel cells.…”

Recent developments in metal‐supported solid oxide fuel cells

“…Novel options such as Inkjet Printing can be tried for depositing barrier layers, as they can be made at the 1–2 µm levels, but this is clearly work in progress. The need to develop an ensuing sintering step is still to be worked out but novel concepts such as plasma heating of surfaces (equivalent to a rapid thermal processing), hold promise.…”

“…Some of the typical complexities during the evolution of a materials processing and cosintering cycle for MSCs include – Sintering of porous metallic support powders are limited by temperature, and cannot take place at conventional ceramic sintering temperatures (1400‐1500°C); in case of ferritic steels, temperatures higher than 1200°C enhance counter‐diffusion of Ni (from the contiguous anode functional layer) and Fe, Cr (from the support), during the approach toward the melting point of the alloy (1400‐1500°C is the melting region for SS430, SS446) As mentioned earlier by Tucker, overdensification will result in the collapse of the pore structure and a drastic reduction in porosity, thereby causing major gas diffusional resistances in the anode. When starting with metallic powders, sintering operations should be carried out under reducing conditions or under vacuum to ensure that CrOx layers do not form on the surface of the support metal powders prior to sintering temperatures. This leads to ‘constrained’ sintering, i.e., very poor adhesion between particles, and consequently poor strength . However, in case of presintered supports with a well‐formed pore structure, the electrolyte and anode functional layers have been sintered in air at temperatures of 1000°C (Ceres Power's technology, which will be discussed further).…”

“…This leads to 'constrained' sintering, i.e., very poor adhesion between particles, and consequently poor strength. 4 However, in case of presintered supports with a well-formed pore structure, the electrolyte and anode functional layers have been sintered in air at temperatures of 1000 C (Ceres Power's technology, which will be discussed further). The CrOx layers formed are electronically conducting and protect the metallic surface from any redox instability arising from flow interruptions of air leaks in the anode chamber.…”

“…To avoid CrOx formation, the switchback to reducing conditions should be done very precisely, and is a nontrivial twostage operation. 4. In a bid to reduce costs and enhance manufacturability, when colloidal methods [screen printing (SP) and inkjet printing] are used to deposit anode and electrolyte layers on top of the metal substrate, they too are constrained in their sintering temperature, which should not exceed the sintering temperature of the substrate.…”