Aluminium service temperature

In the case of the aluminium-magnesium system, most commercial alloys are usually supersaturated, so that elevated service temperatures and inexpert heat treatment are inadvisable, since any resultant grain boundary precipitation may induce susceptibility to intercrystalline attack. The extent of this susceptibility may be approximately deduced from the continuity of... 

Precipitation-hardened alloys can be very strong, but their service temperature is limited. For example, long-time application of precipitation-hardened aluminium alloys at temperatures above 200°C is impossible due to excessive coarsening of the precipitates. To use high-strength materials at high temperatures, another method of particle strengthening can be achieved by... 

Notes Tensile lap shear strength and Service temperature - ASTM D 1002. Tensile Notes SAS420 aluminium-filled version. ... 

It is of interest to note that before the advent of the bismaleimides, and the polyimides in general, high service temperatures were achieved using combinations of solid Bisphenol A-based epoxies with conventional phenolic resoles the interaction between phenolic and epoxy often being promoted by the incorporation of dicyandiamide. The first toughener for high temperature matrices, namely finely divided aluminium powder, was also incorporated into these formulations. ... 

As explained in Section B.6.4, the structure of certain aluminium alloys can change at prolonged heating at rather moderate temperatures, which may modify the mechanical properties and the resistance to corrosion. This is the case with alloys of the 5000 series containing more than 3.5% magnesium, when heated to 70-80 °C or more. The same applies to 7000 series alloys, if the service temperature is on the order of the artificial ageing temperature, i.e. more than 100-120 °C. 

Up to 550°C, aluminium coatings may be used in the as applied condition, and the hot-dipped aluminium-silicon alloy may be used up to at least 680°C, but for service at higher temperatures additional diffusion treatment is recommended for all except Calorised coatings. 

Up to 750°C, the performance of all aluminium diffusion coatings is considered to be very good, but above this temperature the results appear to be dependent on the coating thickness, diffusion treatment and the specific service environment. Sprayed aluminium coatings can be used up to 900°C after diffusion treatment. Hot-dipped coatings also benefit from additional diffusion treatment, and omission of silicon from the coating alloy improves performance at the elevated temperatures. 

Materials suitable for liquid oxygen service are nickel steel, austenitic stainless steels, and copper or aluminium alloys. Carbon steels and plastics are brittle at low temperatures and should not be used on liquid oxygen duty. PTFE is the most widely used sealant. 

In a plant producing common salt, a connecting pin is to be used that has to service in concentrated saline solution at a temperature of 70 °C. The pin is loaded at a stress of Cservice = 100 MPa. The component has to serve for 25000 hours with a failure probability of 0.5% at most. Due to the aggressive environment, a metal cannot be used for the pin. Instead, hot isostatic pressed aluminium oxide (AI2O3) is to be used, characterised by the following parameters ... 

In the field of power capacitors the company claims that its portfolio is number one worldwide with its rugged range of aluminium models able to withstand the high ambient temperatures of car engine compartments. Epcos also makes film capacitors, where the plastic film may be up to ten times thinner than a human hair, and ultracapacitors. The capacitor division also supplies power factor correction modules as a cost saving service to customers. 

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