Performance of Finish-Coated Galvanized Steel Sheets For Automotive Bodies

摘要

Improving performance and reduction of cost are principal concerns for vehicle manufacturers. In addition to shape, the exterior finish is the first thing a consumer sees when looking at a vehicle. The quality and durability of the finish is a reflection of the quality and durability of the vehicle itself. In this work, the behavior of two finish coat systems was studied. Finish coat system 1 included a powder coat, a waterborne base coat and a clear coat. Finish coat system 2 included the same powder coat, a solvent-based base coat and a clear coat. These finish coats were applied on unprimed and pre-primed-electro-galvanized, hot-dip-galvanized and galvannealed steel. Before application, for each finish coat two activation treatments were considered: a conventional zinc phosphate for automotive industry and an experimental pretreatment. Three primers were considered. Primer 1 is an organic zinc-rich silicate with a low thickness (near 4μm), primer 2 is a very thin (near 2μm) water-based primer filled with graphite and primer 3 is a conventional electrophoretically applied primer system.