Phosphating Process Auxiliary Treatment Potion (1) Degreasing agent Alkaline degreasing: NaOH, Na₂CO₃, Na₃PO₄ + surfactant Neutral degreasing: non-ionic surfactant (environmentally friendly) (2) Acid wash solution Hydrochloric acid (HCl) or sulphuric acid (H₂SO₄) (5%~20% concentration) Corrosion inhibitor (e.g. hexamethylenetetramine) to prevent overcorrosion
Author: Robby
Phosphating Process Auxiliary Treatment Potion
(1) Degreasing agent
Alkaline degreasing: NaOH, Na₂CO₃, Na₃PO₄ + surfactant
Neutral degreasing: non-ionic surfactant (environmentally friendly)
(2) Acid wash solution
Hydrochloric acid (HCl) or sulphuric acid (H₂SO₄) (5%~20% concentration)
Corrosion inhibitor (e.g. hexamethylenetetramine) to prevent overcorrosion
(3) Surface conditioner
Colloidal titanium phosphate (TiPO₄) solution (pH 8~10)
Used before zinc phosphating to refine the crystals
(4) Passivation sealer
Chromate passivation (Na₂Cr₂O₇, gradually phased out)
Chromium-free passivation (molybdate, silicate, zirconium salt, etc.)
4. Environmentally friendly phosphate solution trends
Nickel-free fluorine-free phosphating: replace nickel with copper, cobalt, etc. to reduce toxicity.
Low-temperature phosphating (<35℃): energy saving, but need special promoter.
Phosphorus-free conversion film (e.g. zirconium system, silane treatment): environmentally friendly alternative.