electrogalvanization

Electrogalvanizing is a process in which a layer of zinc is bonded to steel to protect against corrosion, enhance adhesion, or give an aesthetic appeal. The process involves electroplating, running a current of electricity through a saline-/zinc-based electrolytic solution with a zinc anode and steel cathode. Such zinc electroplating or zinc alloy electroplating maintains a dominant position among other electroplating process options, based upon electroplated tonnage per annum. According to the International Zinc Association, more than 5 million tons are used yearly for both hot-dip galvanization and electroplating. The plating of zinc was developed at the beginning of the 20th century. At that time, the electrolytic solution was cyanide-based. A significant innovation occurred in the 1960s with the introduction of the first acid chloride-based electrolyte. The 1980s saw a return to alkaline electrolytes, only this time, without the use of cyanide. The most commonly used electrogalvanized cold-rolled steel is SECC, acronym of "steel, electrogalvanized, cold-rolled, commercial-quality." Compared to hot-dip galvanization, electrogalvanization offers these significant advantages: Lower thickness deposits to achieve comparable performance Broader conversion coating availability for increased performance and colour options Brighter, more aesthetically appealing deposits

==History== Zinc plating was developed and continues to evolve to meet the most challenging corrosion protection, temperature, and wear resistance requirements. Electroplating of zinc was invented in 1800, but the first bright deposits were not obtained until the early 1930s with the alkaline cyanide electrolyte. Much later, in 1966, the use of acid chloride baths improved the brightness even further. The latest modern development occurred in the 1980s, with the new generation of alkaline, cyanide-free zinc. Recent European Union directives (ELV/RoHS/WEEE) prohibit automotive, other original equipment manufacturers (OEM) and electrical and electronic equipment manufacturers from using hexavalent chromium (CrVI). These directives, combined with increased performance requirements by the OEM, has led to an increase in the use of alkaline zinc, zinc alloys and high performance trivalent passivating conversion coatings.