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This study presents a fabrication process via experimental observations for curved porous multilayer structures with a single‐step, co‐sintering operation. Active monitoring of the shrinkage behavior of each porous layer during the co‐sintering process leads to minimize mismatched stresses along with avoidance of severe warping and cracking. During co‐sintering, in‐plane stresses are developed in each layer due to differing shrinkage behaviors between layers. Analysis of curvature evolution using in situ monitoring of the structure was performed in the design of a curved multilayer structure via the co‐sintering process. Materials used are NiO/CGO for anode; CGO for electrolyte; and LSCF for cathode. These materials are tape casted with 20 μm thickness and stacked to form bi‐ and triple‐layer structures by hot‐pressing. Bilayers, consisting of NiO/CGO‐CGO and CGO‐LSCF, were co‐sintered up to 1200°C. The maximum sintering mismatched stress was calculated at the interface of bilayer structure. In situ observation, to monitor the shrinkage of each material and the curvature evolution of the bi‐ and triple‐layer structures, was performed using a long focus microscope (Infinity K‐2). Thereby, viscosity, shrinkage rate of each material, and curvature rate were calculated to determine the mismatched stresses. The monitored results contributed to development of novel design of curved 3D multilayer structures during co‐sintering.

Novel multi-junction thermocouple architecture was developed and simulated to in-situ monitor the temperature distribution over a Solid Oxide Fuel Cell (SOFC). This thermocouple architecture requires only {N+1} number of wires for N number of independent temperature measuring points. Therefore, N+1 architecture can independently measure temperature at multiple points simultaneously with much less number of wires than a set of thermocouples require for the same number of independent temperature measurements. Requiring less number of external wires is a distinct advantage, particularly, in constrained environments such as those within SOFC stacks. A thermocouple array having 4 independent temperature measuring points with 5 thermo-elements was simulated in MATLAB. Alumel (Ni:Al:Mn:Si-95:2:2:1 wt) and Chromel (Ni:Cr-90:10 wt) were chosen as thermo-element materials because of their wide applicability in the industry as K-type thermocouples. The junctions were considered to be spot welded. Three sets of simulations were performed to investigate two aspects: validation of the multi-junction thermocouple concept and investigation of the effect of the heat affected zone created in spot welding to the temperature measurement. Simulation code generates random temperature values for each junction within a pre-defined range. Temperatures at the boundaries of heat affected zones were also generated randomly according to a pre-defined criterion. The change of Seebeck coefficients within the heat affected zone was set as a percentage change of their corresponding materials Seebeck coefficient. The temperature gradient induced emf values for each sensing point were calculated from Seebeck coefficients. The calculated emf was then mapped back to temperature using ASTM approved inverse conversion function. These mapped temperatures were then compared with the set temperatures for each junction and they were in very good agreement.

Greigite (Fe3S4), which have ferromagnetic in inverse thiospinel (AB2S4), is widely researched to use an adsorbent and biomedical field because non-toxicity and abundant in nature. Iron-based materials are known to have a high theoretical capacity because of their multivalent state including redox pairs, but still suffer from collapse and aggregate during the charge/discharge process. Here, the synthesized Fe3S4 nanosheet structure materials wrapped with reduced graphene oxide (Fe3S4NSs@rGO) were used as an anode electrode material for sodium-ion batteries (SIBs). The nano-sheet structure facilitates ion diffusion through expanded surface area, and rGO can effectively improve electrochemical conductivity and structure stability. As-prepared Fe3S4NSs@rGO were used as a host material to insert Na-ion via a conversion process, and the stabilized structure maintains the high capacity and long cycle performance. Thus, the Fe3S4NSs@rGO deliver a reversible capacity of 950 mAh g−1 after 200 cycles at a current density of 1A g−1 and 524 mAh g−1 after 400 cycles at a current density of 2A g−1, which is much higher than reported materials.