Phosphate Conversion

Phosphate conversion is the treatment of metals with acidic phosphate solutions. This process converts the metal surface into a phosphate coat.

The phosphating process produces a nonmetallic, oil-absorptive coating on iron and steel surfaces.

Benefit of such coating are as follows:

  • Permits rapid break-in of moving parts without scuffing or welding by preventing metal to metal contact between the bearing surfaces.
  • Increases lubrication of treated surfaces due to the oil-absorptive coating.
  • Removes light metal scratches remaining from machining operations.
  • Retards corrosion.
  • Promote the adhesion of paints

    Types of Phosphate Coatings

    1. Zinc Phosphate (3 to 5 microns thick, light gray in colour)
    2. Manganese Phosphate (4 to 10 microns thick, dark gray in colour)