Hot dip galvanized sheet is widely used in the field of home appliances. For different purposes of hot dip galvanized home appliances, the surface treatment process is also different. The hot-dip galvanizing electrical appliance board is mainly divided
into appearance parts and function parts. Among them, the surface of appearance parts is generally coated, mainly including spraying and color coating; the surface of function parts is generally only treated by chemical treatment, and the most widely
used is passivation treatment.
Surface treatment process
The purpose of surface treatment is to improve the service life of products in harsh environment and to obtain the required surface effect or function. According to the surface treatment, the hot-dip galvanizing electrical
appliance board is mainly divided into chemical treatment steel plate and coating steel plate. Chemical treatment of steel plate is to treat the surface of galvanized steel plate with chromate or phosphate, so as to improve the corrosion resistance, coating
adhesion, fingerprint resistance and lubrication of galvanized steel plate. Among them, chromate passivation is widely used as a separate surface treatment process. Coated steel plate is the surface of galvanized steel plate to be coated and coated, the
main process is divided into spraying and color coating.
Passivation treatment. If the galvanized sheet is exposed to the air for a long time, the surface of the sheet will appear white rust due to oxidation, which will affect the appearance. Therefore,
the surface needs to be passivated to prevent rust. At present, chromate passivation is mainly used for passivation, including environmental protection passivation, all chromium free passivation and fingerprint resistant passivation. Among them, the environmental
protection passivation is common passivation, and the passivation film contains trivalent chromium; the all chromium free passivation film does not contain chromium at all, which is more environmentally friendly and has better corrosion resistance than
the environmental protection passivation film; the fingerprint resistant passivation is specially developed to solve the problem of rusting due to fingerprint contamination in the assembly process of home electric boards, and the passivation film also
does not contain chromium at all, which meets the environmental protection requirements of high standards. In addition, Nippon Steel has also developed a chromate film with strong corrosion resistance, which can meet the requirements of processing performance
and appearance, and can be stably produced in the continuous production line.
The passivation treatment process is generally roller coating. Its working principle is to add the passivation liquid into the material tray, dip the passivation liquid in the material tray when the liquid taking roller rotates, and transfer it
to the surface of the coating roller with the rotation of the roller, and then the coating roller is applied to the surface of the galvanized plate. Environmental protection passivation is generally in the forward direction, while all chromium free passivation
and fingerprint resistant passivation are generally in the reverse direction. The forward coating can provide a thin passivation film, and the roll consumption is low; the reverse coating can provide a thick passivation film, but the roll consumption
is large. After the chemical passivation treatment, the galvanized sheet ne