Applications

The appearance and properties of lead limit its commercial use in electroplating largely to corrosion protection and bearing applications-two fields in which the physical and chemical properties of lead render it unique among the commercially plated metals. Lead has not been extensively electroplated because its low melting point of 325 °C (620 °F) facilitates application by hot dipping. Electrodeposited lead has been used for the protection of metals from corrosive liquids such as dilute sulfuric acid; the lining of brine refrigerating tanks, chemical apparatus, and metal gas shells; and barrel plating of nuts and bolts, storage battery parts, and equipment used in the viscose industry.

Electroplated lead has been used for corrosion protection of electrical fuse boxes installed in industrial plants or where sulfur-bearing atmospheres are present. Lead is also codeposited with tin for wire plating, automotive crankshaft bearings, and printed circuits.

Nonporous lead deposits with thicknesses of 0.01 to 0.025 mm (0.4 to 1 mil) give good protection against corrosion, although the coating may be subject to breaking during abrasion due to the soft nature of lead. Better mechanical properties and improved durability are obtained with coating deposits with thicknesses greater than 0.025 mm (1 mil). Depositing more than 0.08 mm (3 mils) of lead is relatively easy, in that a deposit of about 0.1 mm (4 mils) can be produced in about 1 h at 2 A/dm2 (19 A/ft2) (Ref 1).

Reference cited in this section

1. H. Silman, G. Isserlis, and A.F. Averill, Protective and Decorative Coatings for Metals, Finishing Publications Ltd., 1978, p 443-448

0 0

Post a comment