Aerospace applications satellites

Liquid lubricants have been used in spacecraft mechanisms since the earliest satellites were launched. The vast previous experience gained in terrestrial applications with liquid lubricants means that they were the obvious choice in the early applications and they remain in widespread use today. Some of the advantages of liquid lubrication for aerospace applications, whether by oil or grease, are as follows ... 

Beryllium is used commercially in three major forms as a pure metal, as an alloy with other metals, and as a ceramic. The favorable mechanical properties of beryllium, e.g., its specific stiffness, have made it a major component for certain aerospace applications in satellites and spacecraft. As a modulator and reflector of neutrons, beryllium is of interest in fusion reactions and for nuclear devices that have defense applications. When a small amount of beryllium is added to copper, the desirable properties of copper (i.e., thermal and electrical conductivity) are kept but the material is considerably stronger. The superior thermal conductivity of beryllium oxide ceramics has made the product useful for circuit boards and laser tubes. A more complete discussion of the applications of beryllium was recently reviewed [2]. 

Nickel/hydrogen batteries are closely related to the nickel/cadmium battery, since they employ the same positive electrode and the same electrolyte. They have been developed for aerospace applications and are still the number one energy storage system in many satellite projects 60. 

Space program managers have seriously considered Ni-Hj batteries for communication satellites. These batteries were originally developed for aerospace applications and have been in continuous development since the early 1970s for satellite... 

Lithium-sulfur-dioxide primary batteries are most ideal for military, aerospace, and satellite communications. These low-cost batteries are best suited for applications in which high pulse-power capability and a wide operating temperature range (from -55 to +70 C) are the basic performance requirements. 

Batteries and Fuel Cells for Aerospace and Satellite System Applications... 

Nickel-hydrogen Long cycle life under shallow discharge, long fife Primarily for aerospace applications such as LEiO tmd GEO satellites... 

Aerospace applications have always been extensive and are still growing, due to the outstanding resistance of these sealants to extremes of temperature and various forms of radiation. Sealants designed to emit virtually no volatile components in the high-vacuum environment of deep space are used to fasten solar panels in place and to perform other sealing functions in delicate satellite assemblies where stray condensable contaminants must be avoided near sensitive optical and electronic devices. Other sealants are used to fasten space shuttle tiles in place and for other applications where the maintenance of elastomeric properties is essential over a wide range of temperatures. 

In aerospace applications, as discussed in Chapter 16, different applications have different demands on lithium-ion batteries. For example, in the case of low-earth-orbit satellites, a typical 25 Ah lithium-ion battery should have a cycling life of >60,000 at 25% DOD. At present, a battery based on LiCo02 and graphite with a capacity of 100 Ah can cyclize over 30,000 times. In contrast, a geostationary satellite needs a battery that can be used for over 14 years at 80% DOD. For such aerospace applications, lithium-ion batteries still need to be improved. 

Because of the high functional values that polyimides can provide, a small-scale custom synthesis by users or toll producers is often economically viable despite high cost, especially for aerospace and microelectronic applications. For the majority of industrial applications, the yellow color generally associated with polyimides is quite acceptable. However, transparency or low absorbance is an essential requirement in some applications such as multilayer thermal insulation blankets for satellites and protective coatings for solar cells and other space components (93). For interlayer dielectric applications in semiconductor devices, polyimides having low and controlled thermal expansion coefficients are required to match those of substrate materials such as metals, ceramics, and semiconductors used in those devices (94). 

Other forms of carbon-carbon composites have been or are being developed for space shuttle leading edges, nuclear fuel containers for satellites, aircraft engine adjustable exhaust nozzles, and the main structure for the proposed National Aerospace plane (34). For reusable applications, a silicon carbide [409-21-2] based coating is added to retard oxidation (35,36), with a boron [7440-42-8] based sublayer to seal any cracks that may form in the coating. 

In the aerospace industry, resinous polymers encompass a wide variety of hardware applications for aircraft, missiles, and space structures. In aircraft, resins are used as a matrix material for primary (flight-dependent) and secondary fiber-reinforced composite (FRC) structures, adhesives for the bonding of metal and composite hardware components, electronic circuit board materials, sealants, and radomes. Missile applications include equipment sections, motor cases, nose cones, cartjon-carbon composites for engine nozzles, adhesive bonding, and electronics. As the exploration of outer space intensifies, applications will become even more exotic. FRC will be used to construct telescopes, antennas, satellites, and eventually housing and other platform structures where special properties such as weight, stiffness, and dimensional stability are important. 

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