Recent Advance in Coated Steel Sheets for Electric Appliances and IT Equipments

As shown in a table, this paper introduces most recent updates on surface treated steel sheets used in electrical home appliances and office information devices. In both pre-coated and surface treated steel the base material is zinc galvanized steel which incorporate the superb corrosion resistance characteristics of zinc. When zinc is removed from the surface, the metal becomes a sacrificial part while protecting the exposed steel surface. For the drawn segments used in bottom section of printers and copiers type of office equipment, chromate coated steel sheet is normally utilized most of which in recent years do not include chromium 6 [Cr(VI)]. Through drying at 85~200 deg C of Cr(VI)-Cr(III)-PO43- system, authors were able to compress the reaction of Cr(VI), Cr(III) and the PO43- to form a new polymer then through de-oxygenation at 200~300 deg C they were able to break it into low molecular weight monomers. In regard to corrosion protection using silica, the corrosion resistance significantly is increase when organic coating is formed on top of chromate film coated steel, this is due to composite that is formed between organic resin and silica. In Japan, the chromium-free pre-coat steel sheet has been in use for AV applications since 1988 while for the white electrical home appliances the application began in 2002.