PVD–IBAD zinc coating development for automotive application

This paper describes the progress made during a 4-year BRITE/EURAM Collaborative Programme11Performed in the framework of the Project BRITE–EURAM Programme BE96-3473 ‘PVD Alternatives to Conventional Zinc Coatings’. velop thinner zinc coatings applied by PVD processing to steel strip, for use in automotive body structures. Alloy and multilayer coating deposition techniques were assessed in the laboratory, the technology later being transferred to a pilot line for the production of wide strip which was used for automotive evaluation. This included processing aspects such as pressing (including wear and friction), welding, adhesive bonding, painting and corrosion tests using cyclic laboratory tests and on-vehicle proving using production models. Results show that a reduction in thickness can be achieved (compared with the 7.5 μm electrogalvanised standard) by using an alloy coating, e.g. Zn–Ti, whilst meeting all usual automotive criteria. The work is regarded as a significant stepping stone in the development of thinner, more environmentally friendly zinc coatings. The adoption of this type of coating will depend on cost and an adequate supply base, but with process modification the indications are that this type of product could be a viable alternative to both hot-dip and electrogalvanised alternatives in the future.