Professor Marcus Rutner und doctoral student Jakob Brunow of Hamburg University of Technology develop a nanopatch for the metal infrastructure.

The nanopatch is an ultra thin coating which is deposited on critical details of heavily used and cyclically loaded metal infrastructure, such as bridges, to postpone crack initiation and significantly extending the lifetime of infrastructure, hence, avoiding premature blocking, repair measures or demolition of important traffic arteries. The scientists were awarded the Harburger Sustainability Award in 2021.

The highly durable nanopatch has a total thickness of about one-eighth of the human hair diameter and consists of about 160 alternating copper and nickel layers which are processed by electrodeposition. This nanolaminate coating is locally applied just on the vulnerable structural joints of steel bridges subjected to high frequent and heavy traffic due to trucks or freight trains. The focus in this study is on the welded joint (see Figure, details a and b). First investigations in this study reveal muliple and probably simultaneously acting material mechanims which enable a superior resistance of the nanolaminate coating against crack initiation and resulting in a multifold extension of lifetime of a cyclically loaded welded joint (see Figure, detail c). The scientists name the reduced roughness of nanolaminate coating, the tight lateral support of the coating preventing extrusions and intrusions, further, the interface density per volume causing deviaton of a crack at each single interface and energy absorption as possible material mechanisms.