Nickel space application

Nickel—hydrogen batteries offer long cycle life that exceeds that of other maintenance-free secondary battery systems and accordingly makes it suitable for many space applications. Three types of separator materials have been used for aerospace Ni—H2 cells— asbestos (fuel-cell-grade asbestos paper), Zircar (untreated knit ZYK-15 Zircar cloth),and nylon. 

Many cathode catalyst materials have been used. For noble metal catalysts, platinum was mainly used in fuel cells for space applications. For terrestrial use, one has to use less expensive materials, and non-noble metal catalysts are therefore mainly employed. Bacon used lithium-doped nickel oxide as a cathode catalyst for high-temperature AFCs. Lithium-doped nickel oxide has a sufficient electrical conductivity at temperatures above 150 °C. Currendy, mainly Raney silver and pure silver catalysts are favored. Developments of silver-supported materials containing PTFE are sometimes successful. Silver catalysts are usually prepared from silver oxide, Raney silver, and supported silver. Typically, the catalysts on the cathode are supported by PTFE because it is highly stable under basic and acidic conditions. In contrast, carbon is oxidized at the cathode in contact with oxygen, when carbon is used as an inexpensive support material. In the past, the silver catalysts frequentiy contained mercury as part of an amalgam to increase the stability and the lifetime of the cathode. Because mercury is partially dissolved during the activation procedure (see below) and during the fuel-cell operation, some electrolyte contamination can be observed. Because of the environmental hazard of mercury, this metal is currently not used in silver catalysts. 

This must not be confused with the nickel-hydrogen battery (NiH2 battery) used in space applications - particularly in the International Space Station (ISS) [MIL THA 03]. 

The silver-cadmium (cadmium/silver oxide) battery has significantly longer cycle life and better low-temperature performance than the silver-zinc battery but is inferior in these characteristics compared with the nickel-cadmium battery. Its energy density, too, is between that of the nickel-cadmium and the silver-zinc batteries. The battery is also very expensive, using two of the more costly electrode materials. As a result, the silver-cadmium battery was never developed commercially but is used in special applications, such as nonmagnetic batteries and space applications. Other silver battery systems, such as silver-hydrogen and silver-metal hydride couples, have been the subject of development activity but have not reached commercial viability. 

The most expensive of the conventional-type secondary batteries are the silver batteries. Their higher cost and low cycle life have limited their use to special applications, mostly in the military and space applications, which require their high energy density. The nickel-hydrogen system is more expensive due to its pressurized design and a relatively limited production. However, their excellent cycle life under conditions of shallow discharge make them attractive for aerospace applications. The cost of cylindrical lithium ion batteries has been decreasing rapidly as production rates have increased and has recently been stated to be S1.22/Wh. ... 

Because of their favorable electrical properties, excellent reliability, low maintenance, rugged design, and long life, nickel-cadmium batteries are used in a large variety of applications, as indicated in Table 26.4. Most of these are of an industrial nature, but this type of battery is also used in many commercial, military and space applications. 

Three microbeam systems were developed at the TIARA facility for application to materials science and biotechnology. A heavy-ion microbeam system installed on a beam line of the 3-MV tandem accelerator is the first one developed to study single-event upset (SEU) of semiconductor devices used for space [36]. The microbeam system can focus heavy-ion beams such as a 15-MeV nickel ion with a spot size of less than 1 pm. In order to observe the SEU phenomena at a specific position of the microdevice, the microbeam system is equipped with a single-ion hit system, consisting of single-ion detectors and a fast beam switcher. 

Beginning with this option, process modification requires not only capital and downtime, but also floor space. This can be a significant barrier in many plating operations, and therefore this option is most easily implemented in new facilities or where substantial reconstruction of process lines is taking place. The concept is to use a non-flowing rinse, or empty tank, to capture process solution for eventual return to the process tank, with or without further separation or concentration. It has seen wide application with nickel and chrome plating, and seems to function quite well. Some concerns have arisen, however. 

It seems to be necessary to convert the primary fuel into hydrogen or carbon monoxide first after this the cell functions well. The best-known application is in the combustion of hydrogen in aqueous potassium hydroxide electrolyte with nickel electrodes at 200°C, as used in the Apollo series space flights. 

In view of the above applications and of the fact that extensive literature is actually available on the CVD of aluminum, copper, and tungsten, processing of nickel films has been chosen in this chapter as an introduction to the actual challenges in the CVD of metals. This field is large, especially if it is considered to include deposition on substrates such as preforms, membranes or, particles. Because of space limitations no attempt has been made to provide a comprehensive overview. Although the choice of materials to be discussed was of necessity subjective, it is expected that the present approach will be useful for the investigation of different cases of metal CVD. 

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