Sealing and Passivation Chemicals
We offer a range of sealing and passivation chemicals for improved corrosion resistance and surface protection.
Passivation Chemicals
Passivation is a final-stage protective treatment applied after zinc, manganese, or phosphate coating processes. It is designed to enhance corrosion resistance and improve the durability of treated metallic surfaces.
These chemicals are formulated for application on clean phosphated surfaces or paint base coatings and are typically used on zinc, manganese, and phosphate-treated components by dip or immersion methods.
Passivation is generally carried out at room temperature using low concentrations (approximately 0.1–0.3%). It forms a protective barrier that reduces air and moisture diffusion to the base metal, thereby improving corrosion resistance.
In addition, the process helps neutralize residual ions on the surface, further stabilizing the coating system.
However, exposure time must be strictly controlled, as prolonged contact with chromic acid-based systems may lead to undesirable corrosive effects.
Types of Passivation Chemicals
1. Chrome Passivation
Chrome passivation is an effective final-stage surface treatment applied prior to painting or coating processes. It enhances paint adhesion and prepares the metal surface for subsequent applications, resulting in improved corrosion resistance and coating durability.
This chromium-based passivation process is typically carried out at ambient temperature using a chemical concentration of approximately 0.2–0.3%.
The treatment solution contains hexavalent chromium ions; therefore, proper waste treatment is required to convert chromium into its trivalent form before discharge, in compliance with environmental safety standards.
Chrome passivation significantly improves the corrosion resistance of painted and powder-coated metal components, making it suitable for industrial finishing applications.
2. Chrome Free Passivation
Chrome-free passivation is used to eliminate harmful ionic residues originating from water and surface contamination. It is applied by either spray or immersion methods depending on process requirements.
This treatment enhances underfilm corrosion protection and improves paint adhesion on metallic surfaces. It also contributes to a more uniform and homogeneous phosphate layer while providing additional corrosion resistance by removing ions such as calcium and magnesium, which can otherwise form corrosive salts beneath paint coatings.
Process Parameters
- Bath pH: 4.0 – 6.0
- Chemical concentration: 0.1 – 0.3%
- Treatment time: 45 – 60 seconds
- Application methods: Spray or immersion
Excessive exposure time in the passivation bath should be avoided, as it may lead to slight softening or peeling of the phosphate coating.