Lead Plating

the application of a coating of lead, sometimes containing tin or antimony, to the surface of metal articles in order to increase corrosion resistance to such chemically aggressive substances as sulfuric and sulfurous acids and gasoline and to shield the articles from the effects of X rays. Lead plating is also used in the manufacture of bimetal.

Lead plating is carried out by immersing articles in molten metal—the hot-dipped method—and by electroless plating, metallization, cladding, and electroplating. In lead plating by immersion, either tin (2–25 percent) or antimony (1–10 percent) is added to the molten lead, since neither iron nor copper—the principal materials subjected to lead plating—forms chemical compounds with lead or solid solutions of appreciable concentration. Electroless plating usually involves a preparatory coating of the article with a thin layer of tin; molten lead is then sponge-plated to the surface. Lead plating by metallization is primarily used to coat large prefabricated structural members. Cladding is used in the manufacture of bimetal sheets, pipes, and anode plates. Electroplating with lead is carried out in fluosilicate, fluoborate, perchlorate, and sulfamate electrolytes. The thickness of the lead coating is 0.1–0.2 mm for protection against atmospheric corrosion and as much as 1–2 mm for protection against chemicals.