Cathode and Anode Seal

For the cathode seal material, there is a criterion that the thermal expansion coefficient of the metal component must be lower than that of the a-alumina header. A nickel-cobalt-iron alloy (NiloK) with a 

The anode seal which closes the sodium compartment is a nickel—chromium alloy (Inconel 600). The application of Inconel 600 minimizes the growth of thick inter-metallics and it was shown that seals of this material have been operated for over three years. Contrarily to Inconel, the application of mild steel as the anode seal material gave a life of only 6000 h due to gross intermetallic growth which caused sodium attack of this intermetallic layer in the mild steel. 

Besides the necessity for corrosion resistance in seals, seal stresses generated during thermal cycling must not fracture the bond interfaces. The anode as 

---

Based on the general scenario provided above, the analytical method to determine transference or transport numbers has been devised and is carried out in an apparatus which can essentially be regarded as an improvement over the Hittorf apparatus. This consists of two vertical tubes connected together with a U-tube in the middle all three tubes are provided with stop-cocks at the bottom. The U-tube is also provided with stop-cocks at the top by closing these, the solutions in the cathode and anode limbs can be isolated. The silver anode is sealed in a glass tube as shown, and the cathode is a piece of freshly silvered silver foil. The apparatus is filled up with a standard solution of silver nitrate and a steady current of about 0.01 ampere is passed for 2-3 hours. In order to avoid the occurrence of too large a change in concentration it is necessary to pass the current only for a short duration. The... 

During SOFC operation, interconnects interact with surrounding gaseous environments on both the cathode and anode side, as well as with adjacent components such as sealing materials, electrodes, and electrical contact layers inserted between interconnects and electrodes. These interactions potentially cause corrosion of metallic interconnects and affect their stability and performance. 

Rotating anode X-ray generators, one of which is shown in Figure 7.3, have an arrangement of cathode and anode essentially the same as for the sealed tubes described above. The tubes, however, are not evacuated and sealed, but continuously pumped by a diffusion pump backed by a conventional roughing pump. The environment is therefore the same as the inside of the sealed tube. The second important feature of the rotating anode device is exactly that implied by its name. The anode, which is a hollow disc of copper (usually) several inches in diameter, is rotated at 3000 to 6000 rpm by an external motor so that the beam of electrons emitted from the cathode falls on a continuously changing surface. Water,... 

Using multilayer ceramic technology, the thickness of the fuel cell is reduced, in part by the use of ceramics fluidic channels and inherent insu-lative characteristics (Figure 6-2). The fuel channels are incorporated inside the ceramic substrates. This allows the fuel to be protected from contaminates as well as allow for sealing due to ceramics ability to be hermetic when designs require complete sealing. This quality provides a mechanical structure which can effectively supply fuel to the MEA as well as seal off the MEA to optimize efficiency and prevent contamination. In addition, the ceramic separator plates are coated with metals which allow for the interconnection between the cathode and anode sides of the MEA for purposes... 

The cathode was a machined block of graphite with three parallel flow channels 2 mm x 2 mm x 30 mm long. The entire graphite block was press fit into a larger piece of Teflon for electrical isolation. The flow channels initiated and terminated in common manifolds in the Teflon block at either end of the graphite flow channels. The anode had the same chaimel structure, except that it was made of six graphite pieces separated by Teflon spacers inserted into a Teflon block, as shown in Figure 3.5A.An MEA was placed between the cathode and anode and sealed in the same way as for the differential fuel cell. 

Metallic interconnects are composed of active areas (both cathode and anode), and peripheral non-active, seal areas. Both areas require excellent oxidation and chromium volatilization resistance, however, the active area also needs to be electrically conductive to minimize ohmic losses through the cell, whereas the primary function of the non-active sealant area is to be chemically inert and provide a sealing surface. 

These TF batteries use a lithium-phosphorous-oxynitride (LiPON) ceramic electrolyte that was developed by ORNL. The battery cathode is made of lithium cobalt oxide (LiCoOj) and the anode is made from lithium. Both the cathode and anode contain no liquid or environmentally hazardous material. Even though the lithium material is slightly toxic, the small amount of lithium in the microbattery would not cause a fire if the hermetic seal was broken. Thus, the battery offers optimum reliability and the safest operation over its stated life. 

Sealless planar Electrochemical cells made up of electrolyte, cathode, and anode are stacked with metal interconnects without using sealing materials. For example, disk-type planar sealless stacks have been constructed by Mitsubishi Materials Corporation. For this purpose, fuel and air are introduced through the central part of the respective cells. Outside the cells, the remaining fuel becomes combusted with air. Self-supporting cells are usually used for this design. 

These alloy coatings have advantages over tin in atmospheric exposure where there is heavy pollution by oxides of sulphur. They are cathodic to steel and anodic to copper. In industrial atmospheres, however, formation of a layer of lead sulphate seals pores and produces a generally stable surface and terne-plate has been used extensively as roofing sheet, especially in the USA. It is easily and effectively painted when additional protection is required. Copper heat exchangers in gas-fired water-heaters may be coated by hot dipping in 20% tin alloy . 

A prerequisite of long-life sodium/sulfur batteries is that the cells contain suitable corrosion-resistant materials which withstand the aggressively corrosive environment of this high—temperature system. Stackpool and Maclachlan have reported on investigations in this field [17], The components in an Na/S cell are required to be corrosion-resistant towards sodium, sulfur and especially sodium polysulphides. Four cell components suffer particularly in the Na/S environment the glass seal, the anode seal, the cathode seal, and the current collector (in central sodium arrangements, the cell case). 

---