Use of coatings to protect steels against lead corrosion at high temperatures

The production of high-quality composites resistant to liquid lead corrosion is made possible by thermal-spraying protective layers on high temperature steels. Plasma-spraying is the most suitable method for coating with high melting substances. Adhesion and corrosion protection are improved significantly by using mixed layers. A further increase in adhesion is achieved by high temperature annealing of the composites. For all tested steels the corrosion resistance is enhanced by coatings with suitable layers. The best results are achieved with the austenitic-ferritic steel X 20 CrNiSi 25 4 (1.4821) coated with a plasma-sprayed molybdenum protective layer. Even at temperatures higher than 1350 K and after a testing time of 100 hrs no corrosion attack could be observed. (orig.)