P98.00-0771-12
Pre-treatment / zinc-phosphatizing
Together with electro-dipcoat primer, zinc-phosphatizing ensures corrosion protection for the bodies. In addition it ensures maximum adhesion for the subsequent paint layers.
Before phosphatizing, the body-in-white is degreased with a mild alkaline diluted solution then cleaned and rinsed with demineralized water.
During the phosphatizing process a crystalline protective layer of zinc-iron phosphate is produced on the steel or zinc-coated steel sheets. The surface of the material changes into a corrosion-protecting phosphate layer which is permanently attached to the base metal. It increases the adhesive strength of the subsequent paintwork while preventing subsurface migration or subsurface rusting.
Further rinsing operations with demineralized water remove the excess phosphatizing solution resulting in a chemically neutral body surface.
The illustration opposite shows two examples of pre-treatment systems.
A Immersion pre-treatment
B Spray pre-treatment