A Steel Passivation Compound Free of Heavy Metals

Germany - For the first time, BASF will be presenting a pioneering passivating compound that is free of chromium and fluoride for use on galvanized steel strip at the 2007 Hanover Fair. This innovative BASF product has been developed in cooperation with voestalpine Stahl GmbH. BASF’s Lugalvan® passivating compound has performed successfully in trials in voestalpine’s production facilities and in other European and American steelworks.

“We were looking for a non-toxic compound that was free of heavy metals and that could be used in conversion coatings and decided to combine our expertise in steel with BASF’s chemistry know-how to develop this chromium- and fluoride-free alternative,” said Martin Fleischanderl, head of the project at the Austrian steelmaker voestalpine.

The new Lugalvan passivating compound is completely organic and has been tested in extensive production trials. According to Fleischanderl, it fulfills the requirements of voestalpine and its customers for corrosion protection, visual appearance, paint adhesion, workability, welding and surface resistivity.

“We have made a technological breakthrough in terms of quality and environmental protection,” said Mirjam Herrlich-Loos, Ph.D., head of metal surface treatment projects at BASF. “In addition to protecting the base metal from corrosion, this passivating compound also forms a self-repairing layer. Previously, this was only possible with chromates.”

Cold forming processes can damage the passive layer on the metal surface, but passivation with Lugalvan improves the corrosion resistance of unpainted metal surfaces substantially.

Coatings based on the Lugalvan passivating compound can be applied with the same machinery as conventional anti-corrosion coatings. For example, it only takes a few days to change over to this environmentally friendly product in order to fulfill the requirements of the EU End-Of-Life Vehicles Regulations that come into force on 15th July 2007. Like the EU Restriction of Hazardous Substances Directive, which has been in force since July 1st, 2006, this legislation prohibits the use of certain heavy metal compounds including chromates.

The Lugalvan passivation compound does not have to be removed in subsequent processes, and it acts as an adhesion promoter.