Formability of ultra-thin plasma-polymer films deposited on metal sheet: mesoscopic and nanoscopic aspects of defect formation

Abstract

Forming of pre-coated metal sheet becomes of increasing importance in various fields of industrial application. For instance, the trend in automotive industry goes for ready coated steel sheet that can be formed and cut without loss of performance. This so called “finish first, fabricate later” concept increases the value of the steel sheet supplied by the steel industry and releases the automotive industry from the burden of the coating process. Consequently, studies on the effect of forming on the performance of corrosion protective coating systems adhering to metals sheet are carried out in order to determine the forming limiting curves for existing coatings [1]. New coating systems are sought in order to improve the formability of coating/metal sheet composites. As a very promising step into this direction, in the recent years ultra-thin plasma-polymer films have emerged as candidates for substituting phosphatation and the environmentally critical chromatation as pre-treatments for steel sheet. These Si-containing plasma polymers provide good corrosion protection properties to steel as well as to zinc-coated steel [2–3].