On February 13, the members of the zinc-nickel working group met for their first meeting of the year at MacDermid Enthone in Langenfeld.
The agenda for the hybrid meeting began with a presentation by Nico H. Bajorat, Head of Energy and Sustainability at WHW Hillebrand, on the energy balancing of in-house electroplating processes. In the ensuing discussion, there was a consensus that ZnNi coatings have a slightly higher carbon footprint than conventional Zn coatings, partly due to more complex wastewater treatment, but that this is offset by the longer service life of the surfaces. The next step will be to prepare these considerations for publication within the working group. Another point of discussion was the phenomenon of so-called budding on ZnNi surfaces, which leads to a significantly increased screw-in torque, particularly on the thread flanks of screws. Sascha Große from Volkswagen AG showed the cauliflower-like structure that forms in individual cases using representative SEM images. According to the findings of the ZnNi working group, the main causes of budding are inadequate bath maintenance, insufficient use of additives and high total currents. The working group appeals to all screw suppliers to observe the current state of the art. Finally, Dr. Michael Brilz from TU Darmstadt reported on the latest findings on the fracture mechanics of hydrogen embrittlement in high-strength steels, which were discussed intensively in the subsequent discussion.
