Plasma treatment of cold-rolled steel: actual state, problems to overcome and future

The corrosion protection of steel substrates is an important industrial process for many industries such as the automotive industry, the packaging industry etc. The most common methods of corrosion protection of steel surfaces are actually hot-dipping and electrodeposition. However, these methods suffer from several drawbacks: weak variety of coatings, multilayer deposition nearly impossible, important disposal and recycling costs. It is known that plasma deposition (including sputtering) of thin films can give a very dense structure with uniform deposition, low number of pinholes and adequate long-term corrosion performances. Most of the work in the plasma deposition has been restricted to small objects. Plasma processing for larger objects has been used preliminarily for plastic and glass substrates, but rarely on metallic substrates. In this paper, we shall discuss some of the literature and personal work related not only to surface cleaning and corrosion protection of steel but also to interface engineering for the improvement of paint adhesion. Type of coating, properties achieved will be discussed bearing in mind the industrial application. In addition, some technological aspects related to a continuous in-vacuum coating line will also be addressed. Finally, a few guidelines will be drawn for the implementation of vacuum technology in industry. (C) 1998 Elsevier Science S.A.