Nachhaltige recyclingbezogene Aluminium-Legierungen
Research output: Thesis › Master's Thesis
With an annual world production of approx. 90 million t, aluminium ranks second of all metals after iron. The low density, the low price and the excellent corrosion resistance lead to a wide range of applications for aluminium alloys. These include the transport, construction and packaging sectors as well as electrical engineering. However, the primary production of aluminium is very energy-intensive. Recycling can reduce energy consumption by 90–95%. Problematic for long-lasting products, e.g. automobiles, is an imbalance between scrap availability and demand. A complete separation of aluminium alloys as well as the separation of wrought and cast alloys during scrap processing often fails at present due to economic efficiency. Due to the ignoble character of aluminium, the removal of foreign elements is often thermodynamically and economically not possible. These reasons lead to the currently widely used strategies of dilution with primary aluminium and downcycling. In the latter case, the product of the joint melting process of wrought and cast alloys is a cast alloy, the main application of which is in the internal combustion engine. Increasing market shares of electric vehicles are causing the market for these casting alloys to shrink. For this reason, this thesis examines the large application area of aluminium alloys in the automotive sector. The compositions of potential scrap mixtures are calculated by three representative cars based on literature data and an “educated guess”. These are an average vehicle from EU production, the Ford F150 pickup and the Tesla Model 3. Various dismantling scenarios are also considered, ranging from “without dismantling” to “theoretical possible dismantling”. Each of these alloys is manufactured, homogenized and rolled into tensile samples on a laboratory scale. Scanning electron microscopic (SEM) examinations conclude the experiments. In summary, cold-rolled sheets were successfully produced from all the alloys studied. Investigations via SEM showed accumulations of the elements Mg, Si, Fe and Mn at the grain boundaries. Zn was randomly distributed in all samples; both distribution scenarios occurred for Cu. Further research should concentrate on the heat treatment of the alloys. A focus should also be placed on the acquisition of reliable data to reduce the influence of “educated guess” on future alloy compositions from end-of-life vehicles.