Corrosion prevention in multi-material automotive structural components

A. Chavoshi1*, C. Ehemann, M. Fleischmann1, J. Emmrich1, J. Kaufmann1, H. Cebulla1, F-L Kroll1

1 Technische Universität Chemnitz

*nader.chavoshi@mb.tu-chemnitz.de

Manufacturing sector is constantly in demand for superior composite materials that can cope with the requirements for increased mechanical qualities to create wide applications in various industries [1], such as automotive structural body parts (fig. 1). New automotive structural components made of carbon and glass fibre preforms in combination with metal (aluminium and steel) sheets were developed in this study with the goal of reducing component weight and CO2 emissions, increasing component strength, improving failure characteristics, offering better joining techniques, and lowering costs.

The interface region plays a significant role in defining the ultimate properties of the multi-material-composite as it occupies a large area in structure [2]. The contact between carbon fiber and metal plate at the interface is a challenge with these materials. Because carbon fiber is electrically conductive and has a higher electrochemical potential than both aluminum and steel, galvanic corrosion can occur, resulting in the metal plate's slow destruction. This, in addition to reducing part-to-part adhesion, has a negative impact on the overall properties of the composite material, resulting in failure to meet mechanical requirements during the service cycle.

A unique functionalized interface film with integrated spacer fabric is designed and incorporated into the composite structure to avoid this electrical contact. To assess corrosion behavior, samples with various structure designs are subjected to a corrosive environment inside a corrosion chamber and being extracted at predetermined time intervals. Following, light microscopy is used to examine how corrosion affects the surface of the samples. Finally, scanning electron microscopy is used to investigate changes in surface topography and element compositions.

 Figure 1. Delivery van rear door: CAD design (left) and the final part.

References

[1] V. Khanna, V. Kumar, S. A. Bansal, IOP Conference Series: Materials Science and Engineering, 2021, 1033, 012057.

[2] K.K. Chawla, Composite Interfaces, 2012, 4, 287-298.