Abstracts of Technical Articles by Bell System Authors (01 October 1941)

The Scientific Monthly, October 1941. The Monthly Review of the American Electro platers1 Society, September 1941. 439 440 BELL SYSTEM TECHNICAL JOURNAL steel surface, such as results from an alternate oxidation and reduction and by the addition of small amounts of aluminum to the zinc bath. Electroplated zinc deposits have the advantage of being applicable in greater thicknesses than hot-dipped coatings. Electroplating methods have made considerable progress, particularly in the wire field, with the speeding up of plating rates as much as twenty-five fold. 

Bright zinc coatings have been developed in response to the demand for improved appearance and this finish is gradually replacing the older dull type. The protective value of zinc depends directly upon the thickness of the coating. Experiments have listed environments in the order of increasing attack as follows: rural, tropic marine, temperate marine, suburban, urban and highly industrial. The resistance of zinc coatings to corrosion under water depends largely upon the degree of circulation of the water and its oxygen content. When a submerged zinc-coated armored cable is lapped with jute, thereby stagnating the water, the capacity of zinc to resist corrosion is increased. 

Cadmium plate has good color and is very satisfactory for indoor use. It does not possess corrosion resistance equal to zinc under conditions of outdoor exposure. Bright nickel coatings or semi-bright coatings requiring mild buffing have largely replaced the older type of nickel coatings.