Abstract
Clad aluminium strips are used in the automotive industry to manufacture parts of heat exchangers. They are characterised by favourable strength properties, good corrosion resistance and susceptibility to plastic deformation, and can undergo surface brazing at a temperature of about 600°C. As a result of studies, the properties of alloys for the production of clad strips have been optimised. Optimising covered the alloy chemical composition and selected parameters such as the metal condition, the mechanical properties and anti-corrosion behaviour, including the methods for corrosion potential equalisation and sacrificial protection. The obtained technological results of the clad aluminium strip production were verified under the industrial conditions of Impexmetal Huta Aluminium Konin S.A. In a laboratory of the Institute of Non-Ferrous Metals (IMN), the clad strips were tested for the pre-assumed functional properties. Mechanical properties were tested, and the structure and corrosion behaviour were characterised. The reactivity of the clad layer was analysed under different technological conditions. The thermal bond produced by these clad layers was tested by simulation of the heat exchanger manufacturing process. As a result of the conducted research it has been found that all the essential characteristics of the clad strips produced under domestic conditions are in no way different from the properties of imported strips, while modification of the alloy chemical composition has contributed to the effective sacrificial protection of heat exchangers made from these strips. Clad aluminium strips are now successfully produced by the domestic aluminium industry. The improvement of materials used for the heat exchangers can contribute to the reduced overall dimensions of these products and increased efficiency, thus leading to energy savings. The results were obtained within the framework of the Task No. ZPB/38/66716/IT2/10 executed as part of the „IniTech” Project.
Significance of the brazing gap in the brazing of aluminium heat exchangers for automotive industry
