Regensburg 2010 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 26: Poster Session

MM 26.48: Poster

Tuesday, March 23, 2010, 14:45–16:30, Poster C

Vapour galvanizing (Sherardizing) of Copper with Zinc — •Dietbert Wortelen¹, Hartmut Bracht¹, Frank Natrup², and Wolfram Graf² — ¹Westfälische Wilhelms-Universität Münster, Germany — ²Bodycote Wärmebehandlung GmbH, Sprockhövel, Germany

Using a vapour galvanizing technique called Sherardizing we investigated the growth kinetics and coefficients of zinc copper phases. For this purpose polished (OFHC)-copper plates and zinc powder have been sealed in quartz ampoules under inert gas atmospheres and annealed at a temperature range between 300 and 410°C. In order to study the coating thickness and the phase composition, cross sections were prepared, which have been analyzed by means of optical microscopy and scanning electron microscopy. We were able to demonstrate that the coating thickness is a function of the parabolic time law and that the formed coatings are composed of two layers referring to the ordered beta-CuZn and gamma-Cu5Zn8-phases. To enhance the coating quality, small amounts of ZnCl2 were added to the zinc powder. It was observed that the coating thickness decreased with increasing ZnCl2. Experiments with variable Ar-pressure demonstrated a reduced coating growth with increasing pressures. Further measurements with ZnCl2 were performed to check whether an electrochemical mechanism is involved in the coating process.