Sintering solid electrolytes

As discussed below, the porosity and surface area of the catalyst film is controllable to a large extent by the sintering temperature during catalyst preparation. This, however, affects not only the catalytically active surface area AG but also the length, t, of the three-phase-boundaries between the solid electrolyte, the catalyst film and the gas phase (Fig. 4.7). 

The reference electrode-solid electrolyte interface must also be non-polarizable, so that rapid equilibration is established for the electrocatalytic charge-transfer reaction. Thus it is generally advisable to sinter the counter and reference electrodes at a temperature which is lower than that used for the catalyst film. Porous Pt and Ag films exposed to ambient air have been employed in most previous NEMCA studies.1,19... 

Electrode preparation can be a significant problem for some catalyst systems. In general, it is necessary to sinter the catalyst to ensure adherence to the electrolyte substrate. This does not present much of a problem for metal electrodes but for oxides, where a particular phase may be required, the need for sintering can cause difficulties. This review will not, however, deal with the details of electrode preparation rather the reader should refer to an original article for details of preparation of a particular electrode (a short review of electrode preparation in solid electrolyte electrochemical cells can be found in reference S). 

The heater, the underlayer, the zirconia solid electrolyte and the two electrodes are formed by screen printing and sintering. The sintering condition is at 1,U80°C for 2HR in air. The temperature of sensor surface rises to 600°C with plasma spraying. 

Since the principle of the sodium sulfur battery was established in 1967, it has been under development throughout the world. The schematic set-up of a sodium sulfur battery, operated at 300 350 °C, is shown in Figure 22. Molten sodium, the anode active material, is placed in a sintered S-alumina solid electrolyte tube, and molten sulfur impregnated in the porous graphite cathode, outside. The... 

The PEVD system used in this investigation is schematically shown in Eigure 36. A Na -p/ P -alumina disc, 16 mm in diameter and 5 mm in thickness, was used as the solid electrolyte with a working electrode on one side and both counter and reference electrodes on the other. To simplify data interpretation, the same electrode material, a Pt thick film, was used for all three electrodes, so the measured potential difference could be directly related to the average inner potential difference between the working and reference electrode. In order to make good electrical and mechanical contact, Pt meshes, with spot-welded Pt wires, were sintered on the Pt thick films as electron collectors and suppliers. 

Yang, J.H., Wen, Z.Y., Gu, Z.H., and Yan, D.S., Ionic conductivity and micro structure of solid electrolyte La2Mo209 prepared by spark-plasma sintering. Journal of the European Ceramic Society, 2005, 25, 3315-3321. 

Small-size starting particles with an appropriate size distribution that lead to a maximum packing density and final fired density are essential in the sintering step to form dense membranes. The required sintering temperatures are lower because of the active state of the Hne particulate materials used. For example, when particles of an average size of 5 nm made by the alkoxide approach are used to make stabilized zirconia, 1450X instead of the usual 2(X)0X is all that is necessary to produce fully dense material [Mazdiyasni et al., 1%7]. The amount of additives such as the stabilizers affects densification of the final solid electrolyte membranes as well. Generally there is an optimum amount of stabilizer for maximum densification. Excess addition actually can lead to lower densification. 

In order to examine how impurities affect the resistance of both single-crystal and polycrystalline zirconia, samples were prepared and resistance was measured. Samples of polycrystalline zirconia and the zirconia single aystal with the same concentration of Y2O3 were used at temperatures of 400-800 C. The results of testing are shown in Figure 4.8. Based on the fact that the higher the sintering conditions of polycrystalline zirconia, the less the resistance and porosity of solid electrolyte... 

The measuring electrode employed the same catalyst powder [10] which was used to prepare the egg-shell catalyst. It was mixed with an organic binder giving a viscous paste. The solid electrolyte was coated with this paste up to a film thickness of 80 im and sintered for one hour at 320°C, leading to a sufficient adhearence of the porous electrode on the electrolyte. 

Materials often exhibit unique properties, processing challenges, and degradation mechanisms that are inherently electrochemical in nature. For example, the sintering of high-technology ceramics is closely related to the behavior of ionic defects in solid electrolytes. 

These cells contain solid electrolytes fabricated by sintering green ware prepared by electrophoretic deposition. 

Sensor element temperature needs to rise to several hundreds degree centigrade in order to operate as oxygen sensor. Zirconia solid electrolyte is an insulator at normal room temperature and it cannot detect the gases. Therefore, gas detection is not possible until the necessary temperature of the sensor element is reached. Because the time of gas detection is short, a heater is embedded in the sensor element to achieve fast light off. The rod type heater is arranged inside of the side of the reference ambient air of the thimble type sensor element, and then the sensor element can be heated. Heating material is printed on the alumina sheet and is laminated. After that, it is wrapped upon the rod type ceramic and then sintered. Extension of the electrode is structured by terminal. 

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