Sealing & Passivation Chemicals Manufacturers
We have different types of Sealing & Passivation Chemicals products
Passivation Chemicals
After zinc-phosphating, another protective process in the form of a passivation can be applied to the metallic parts. These chemical is specially formulated for use over clean surface or paint base coating particularly Zinc, manganese, and Phosphate type applied by dip or immersion.
Passivation is used at the last stage of phosphating process. It can be used at room temperature with 0.1 – 0.3% concentrations. Passivation prevents air diffusion to base metal. Leaking chromic acid provides extra corrosion resistance. Passivation also neutralizes anions and Cations along with water.
Phosphated parts must not treat in passivation bath. Chromic acid has corrosive effect when applied long time.
There are two types of Passivation Chemicals
1. Chrome Passivation
Passivation is effective when made prior to paintings. It improves adhesion of paint particles and prepares the surface for following applications to have enhanced corrosion protection.
Chromium passivation treatment is used under conditions of 0.2 – 0.3% chemical concentration and at ambient temperatures.
The treatment solution includes hexavalent chromium ions, hence it must be converted to trivalent chromium while discharging. use of this passivation chemicals improves corrosion protection of painted, especially, powder coated metal parts.
2. Chrome Free Passivation
Chrome free Passivation is used to eliminate ionic elements coming from water. It is available to apply the treatment by spraying or immersion.
Chrome free passivation increase underfilm protection of paint metallic surface & increase paint adhesion. Along with shaping the phosphate surface more homogenous and uniform, Chrome free Passivation treatment also provides extra corrosion protection by eliminating ions such as calcium and magnesium that can form corrosive salts under paintings.
pH of passivation bath must be between 4 – 6. Passivation baths prepared with very low concentration of chemicals (0.1 – 0.3%). Treating time of phosphate metal part in the passivation solution is in the range of 45 – 60 seconds.
Excessive time duration in the passivating bath can cause lightly peel off of phosphate coatings.