Aircraft industry

One obvious disadvantage with both the approaches mentioned above is that the attenuation measurements are based on through-transmission, TT, testing which means that we need access to both sides of the specimen and this cannot be guaranteed for many of the complex geometries found, e.g., in the aircraft industry. 

Various expressions have been derived from which corresponding rates for alloys can be calculated. AH these procedures are based on calculating an effective value for the chemical equivalent of the alloy. Thus for Nimonic 75, a typical nickel alloy used in the aircraft industry, a chemical equivalent of 25.1 may be derived (4). The Nimonic alloy is given to have, on a basis of wt %, 72.5 Ni, 19.5 Cr, 5.0 Ee, 0.4 Ti, 1.0 Si, 1.0 Mn, and 0.5 Cu (see Nickel and... 

In the area of superconductivity, tetravalent thorium is used to replace trivalent lanthanides in n-ty e doped superconductors, R2 Th Cu0 g, where R = Pr, Nd, or Sm, producing a higher T superconductor. Thorium also forms alloys with a wide variety of metals. In particular, thorium is used in magnesium alloys to extend the temperature range over which stmctural properties are exhibited that are useful for the aircraft industry. More detailed discussions on thorium alloys are available (8,19). 

Forming-Die Alloys. The tonnage of slab zinc used in this appHcation is small. The use of zinc alloy dies started in the aircraft industry during World War II (119). Zinc-based alloys cast in sand and plaster molds continue to be used for short-mn dies for steel and aluminum stampings in the automotive and aircraft industries (120). Considerable cost savings are realized with these low melting zinc-based alloys which are easy to poHsh, machine, weld, and remelt. 

The principal original use of fluorocarbon elastomers in the aircraft industry now accounts for less than 10% of the total fluorocarbon elastomer consumption. 

Zinc—Nickel. Steel has the best salt spray resistance when the nickel is 12—13% of the alloy. At increasing nickel contents, the deposit becomes more difficult to chromate and more noble, eventually becoming cathodic to steel. At those levels and above, corrosion resistance usually decreases and is dependent on a complete lack of porosity for protection of the steel. In efforts to replace cadmium and nickel—ca dmium diffused coatings in the aircraft industry, 2inc—nickel has insufficient wear properties for some appHcation, but is under study as an undercoat to various electroless nickel top coats (153). 

The gas turbine is a power plant that produces a great amount of energy for its size and weight. The gas turbine has round increasing seiwice in the past 15 years in the petrochemical industry and utilities throughout the world. It is the power source of the aircraft industry. In this section we deal with land-based gas turbines. 

Radial-inflow turbines are only now beginning to be used because little was known about them heretofore. Axial turbines have enjoyed tremendous interest due to their low frontal area, making them suited to the aircraft industry. However, the axial machine is much longer than the radial machine, making it unsuited to certain applications. Radial turbines are used in turbochargers and in some types of expanders. 

Laminates produced by impregnation of glass and carbon fibre with polyimide resins followed by subsequent pressing have found important uses in the aircraft industry, particularly in connection with supersonic airliners. Such laminates can be used continuously at temperatures up to 250°C and intermittently to 400°C. 

Glass cloth. A range of cloths is available and the finest of these are used in order to obtain the best meehanieal properties. They are, however, expensive in use and they are used only in certain specialised applications such as in the aircraft industry and for decorative purposes. 

Epoxide resin laminates are of particular importance in the aircraft industry. It has been stated that the Boeing 757 and 767 aircraft use 1800 kg of carbon fibre/ epoxide resin composites for structural purposes per aeroplane. The resin has also been used with Aramid fibres for filament-wound rocket motors and pressure vessels. The AV-18 fighter aircraft is also said to be 18% epoxide resin/cc bon fibre composite. The resins are also widely used both with fibres and with honeycomb structures for such parts as helicopter blades. 

The adhesion of metal and ink to polymers, and the adhesion of paint and other coatings to metal, are of vital importance in several technologies. Aluminum-to-alu-minum adhesion is employed in the aircraft industry. The strength and durability of an adhesive bond are completely dependent on the manner in which the adhesive compound interacts with the surfaces to which it is supposed to adhere this, in turn, often involves pretreatment of the surfaces to render them more reactive. The nature and extent of this reactivity are functions of the chemical states of the adhering surfaces, states that can be monitored by XPS. 

PVDF IS used as a coating for metallic architectural substrates such as roofing, panel siding, and windows, and for wire insulation in the electronics and aircraft industries It is also used to mold pipes... 

Maraging steels have found varied uses in the aerospace and aircraft industries. These uses have included rocket motor cases, landing gear components, aircraft forgings and fasteners. Other areas of usage include machine tool and die applications, and extrusion hardware. Marine uses include hydrofoil foil systems and aircraft arrester hooks. 

As a light, strong metal, beryllium holds considerable promise as a useful engineering material, but because of an inherent directional brittleness, a really significant commercial use, e.g. in the aircraft industry, has not proved possible. It has been used to a limited extent in aerospace applications, and it was employed as heat shields for the Project Mercury space capsule. It has also found use in precision guidance systems when fairly pure environmental conditions can be assured. 

The possible employment of beryllium in nuclear engineering and in the aircraft industry has encouraged considerable investigation into its oxidation characteristics. In particular, behaviour in carbon dioxide up to temperatures of 1 000°C has been extensively studied and it has been shown that up to a temperature of 600°C the formation of beryllium oxide follows a parabolic law but with continued exposure break-away oxidation occurs in a similar fashion to that described for zirconium. The presence of moisture in the carbon dioxide enhances the break-away reaction . It has been suggested that film growth proceeds by cation diffusion and that oxidation takes place at the oxide/air interface. ... 

Mechanical properties of various titanium alloys are given in Table 5.16. In general the corrosion behaviour of those titanium alloys developed for the aircraft industry is very similar to that of unalloyed titanium . The addition of some alloying elements may increase resistance to one medium, but decrease it to others . 

Corrosion-inhibited petroleum-based waxes deposited from solvent are finding application in both the automotive and aircraft industries for the supplementary protection of hollow sections of the finished product. These waxes are applied by airless or air-assisted pressure-feed spraying techniques... 

Over the years innovations in aircraft have given rise to more new plastic developments and have kept the plastics industry profits at a higher level than any other major market principally since they can meet different environmental and load conditions. Virtually all plastics have received the benefit of the aircraft industry s uplifting influence. Practically all conceivable top quality plastics are used to provide cost advantages and improvements... 

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