At the end of 1980s, Nippon Steel Company of Japan developed a kind of self-lubricating galvanized sheet, which can be used in the stamping process of motor shell.
Firstly, the surface of the galvanized sheet is passivated with chromate, and then the organic lubricating film with a thickness of several microns is coated. This kind of product not only has good corrosion resistance, but also has excellent lubrication
performance. It will soon be used in the stamping process of various electrical appliances and oil tanks.
In the 1990s, the production and application of this kind of organic self-lubricating coating has been commercialized, which occupies a leading
position in the world and is the most representative. However, the self-lubricating coating is an organic lubricating film containing chromium, which is harmful to the environment.
In 1984, NKK steel pipe company of Japan developed a thin organic
high lubricity composite coating uz-l with polyethylene as lubricant and polyurethane as base resin in order to improve the environmental pollution caused by chromium coating on galvanized sheet. In 1993, the coating uzsl was developed.
uz-sl are suitable for complex stamping process and keep good appearance after forming. The organic composite coating uz-c3 was developed in 1996. It takes modified vinyl resin as the main film-forming resin and has high lubricity and excellent coating
In the early 1990s, Kawasaki iron company developed river zinc FS with chromium passivation layer and organic resin coating. It has excellent corrosion resistance, formability, surface quality and fingerprint resistance, but its conductivity
and weldability are not ideal. After that, fc-s was developed with better formability. A two-step production process was adopted, in which chromium free passivation treatment was carried out on the galvanized sheet first, and then a lubricating film was
applied to form an environmental friendly self-lubricating double coating on the surface of the galvanized sheet.
For the three main products gi-f, ga-f and eg-tj of self-lubricating coating of galvanized sheet, the comparative test between them
and zinc sheet was carried out by Koyama iron making Institute and Sumitomo Metal.
Among them, gi-f coating and ga-f coating are respectively made on hot-dip galvanized sheet and aluminum zinc sheet by chromate passivation treatment and coating
organic high lubricating film; eg-tj coating is made on electro galvanized sheet by coating organic resin lubricating film containing chromium. The results show that the three self-lubricating coatings have excellent lubricity and corrosion resistance
compared with the substrate surface.
In addition, Kobe Steel has developed self-lubricating galvanized steel sheet with polyethylene resin as matrix, wax as lubricant and colloidal SiO2 to improve corrosion resistance.