Aluminium structure

The electrode potential of aluminium would lead us to expect attack by water. The inertness to water is due to the formation of an unreactive layer of oxide on the metal surface. In the presence of mercury, aluminium readily forms an amalgam (destroying the original surface) which is. therefore, rapidly attacked by water. Since mercury can be readily displaced from its soluble salts by aluminium, contact with such salts must be avoided if rapid corrosion and weakening of aluminium structures is to be prevented. 

The Al-HjO diagram does show, however, the danger that may arise due to an increase in pH when the metal is cathodically protected in near-neutral solutions indeed, the possibility of alkaline corrosion has seriously limited the use of cathodic protection for aluminium structures. 

An explanation that may be suggested of these facts is that solid solutions of a quadrivalent metal (zinc) in a tervalent metal (aluminium) tend to be unstable because of the difficulty of saturating the valency of isolated quadrivalent atoms by bonds to its lower-valent ligates. With zinc as the solute an increase in free energy at the lower temperatures would accompany the separation into the zinc-poor a phase, in which the versatile zinc atoms tend to assume the valency 3 (less stable, however, for them than their normal valency) in order to fit into the aluminium structure, and the zinc-rich a phase, in which the concentration of zinc atoms is great enough to permit the extra valency of zinc to be satisfied through the formation of Zn-Zn bonds. 

Mazzdlani, F.M. (ed.) (2003) Aluminium Structural Design. Series CISM International Centre for Mechanical Sciences, No. 443, Springer, Berlin Heidelberg New York. 

An optimal combination between aerodynamic and weight requirements was achieved for the Transrapid by modular hybrid (mixed) construction methods. For example, the glass-fibre-reinforced plastic (GRP) front module is designed for maintaining aerodynamic pressure as well as for stability under cross wind forces of 500 km/h, and is bonded to the front of the aluminium structure of the rail cars with Sikaflex products (Fig. 5). 

The preamplifier is usually mounted helow the detector within the overall housing. It comprises a fibreglass printed circuit board, aluminium structural items and a number of electrical items. Especially low activity resistors, eapacitors and the FET are not avaUahle and, because... 

Concrete Structural steel Structural aluminium Structural wood 24kN/m load... 

Aluminium structures Characteristic values based on Euro code-9 fa = ultimate strength L = longitudinal = 310 2 Temper P6 T = transfer = 260 N/mm ... 

MIL-S-81733 Sealing, Coating, Corrosion Inhibitive. MIL-S-83315 Sealing, Aluminium Structure. 

Film adhesive bonding does take place within the overwing and the underwing panels the A.380 makes much use of composite materials to replace aluminium structures, otherwise the design concept for the Airbus family is, essentially, identical. Fig. 89 shows the fully bonded (Redux 319 film adhesive) aluminium box and beam structure used in the A.340. 

Experience has shown that on an aluminium structure that is partly immersed in seawater, water line corrosion may occur as rather scattered, superficial pitting, with a depth not exceeding a few tenths of a millimetre. This can be observed on the uncoated aluminium hull of barges. 

Red lead-based paints or paints containing mercury salts (which are now forbidden by regulations) or copper salts should never be used on aluminium structures. 

Such a luxury insulation is necessary only if the heterogeneous assembly is immersed (or located in an area that will retain water), and provided that safety rules do not obUge the use of a common grounding. In this case, the common grounding will transform the immersed aluminium structures into sacrificial anodes for the cathodic protection of steel constructions. 

The melting point of aluminium is 660 °C. Only two other common metals have a lower melting point magnesium (650 °C) and zinc (419 °C) (Table G.7.1). In practice, as the temperature exceeds 660 °C, aluminium structures will melt but not burn. 

Junctions formed with indium and with chromium also showed reasonable Schottky barrier formation, though we find in general that the ideality factors for these devices were poorer than for the aluminium structures, with values of 2 found in both cases. There is some variation in the barrier height deduced from the value of Jq fitting to the diffusion model using the same parameters as used above we find lower values for < )b, of 0.34 eV for chromium and 0.42 eV for indium. 

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