This specification establishes the materials and procedure for the formation of an insoluble mildly protective iron phosphate coating on ferrous surfaces, having an iridescent blue to bluish brown color. This process will produce coatings in accordance with TT-C-490 TYPE II American specification. The thickness of the coating is over 35 mgr/ft2

Application

Iron phosphate coatings are applied to steel surfaces in order to protect them from corrosion but mainly are applied as a base for better paint adhesion (wet or electrostatic).

1st stage : Degreasing – phosphatizing Product: PHOSPHAT – F Concentration: 5 – 6 % by immersion Temperature: 50 – 60 oC.

Contact time: 5 – 7 min by immersion

2nd stage : Rinsing

Clean overflowing cool water for 1-2 minutes. Dump & refill daily.

3rd stage : Passivation

If the water of the rinsing stage is hard it is preferable to use deionized water or perform the passivation stage which increase the anti-corrosion protection of the metal.

Product: HIB

Concentration: 2 o/oo by immersion or spray. Temperature: 50 – 60 oC.

Contact time: 30 sec.

In some cases the second or the third step may be omitted.

General Information

The tanks or the spray equipment could be made from stainless or mild steel. Depending on the production the PHOSPHAT – F solution must  be changed every month.

The solution of the passivation stage must be changed every 2 – 4 days. If the second step is omitted the HIB solution should be changed daily.