Zink-Magnesium - Neue metallische Überzüge im Metallleichtbau

Zinc magnesium - New metallic coatings for light-gauge steel construction

Construction members made of coil coated thin sheet have over the last decades made their way into light-gauge steel construction. In the beginning the long-life cycle determined by the corrosion inhibiting layers was the mayor concern. Later other aspects came into focus. The process is determined by political influence through legal acts or codes as for example fire codes, Energy Saving or REACH regulation. Such political influence can affect product life cycles and other properties, such as colour impression. Socio cultural aspects are mainly expressed through customer requirements reflected in the impression and form of architectural as well as structural design. Economical effects trigger high demands towards the usage requirements and the (re)saleability of a building. Building envelopes from coil coated light-gauge steel construction have proven to perform excellent with regards to these requirements. Continuous technical developments secure a durable and safe use of these building products, while at the same time retaining good appearance. Organic coil coated steel sheet being the semi-finished product for construction products is under constant pressure to innovate. Besides aesthetic properties particular advancements were made in the development of corrosion protection. By developing a new zinc magnesium based coating for steel sheet, ZM EcoProtect by ThyssenKrupp Steel Europe, and combining it with organic colour coating a distinct improvement of both active and passive parameters in corrosion protection was achieved. Employing the ZnMg coating that contains app. 1 % of magnesium opens the possibility to reduce the coating thickness while keeping the same level of corrosion protection. Doing so preserves the limited natural zinc resources. This new organic coil coated steel sheet for construction products has been officially approved by the Deutsche Institut für Bautechnik (German institute for building products) in the beginning of 2008 and is currently under approvement in France by means of a CSTB evaluated expert report. Finally an European technical approval can be achieved regulating the use in the whole of Europe. Some application examples are presented.