What is a trivalent passivate?
A hexavalent-chromium-free chemical finish applied right after zinc plating to delay the onset of white corrosion and define the final color (blue, yellow or black).
Process sheet · Zn
Alkaline zinc
A cyanide-free electroplated coating that deposits a uniform layer of zinc onto steel parts. Zinc acts as a sacrificial anode: if the part is scratched or exposed to humidity, the coating corrodes first in a controlled way, keeping the steel intact. It provides excellent metal distribution on complex geometries and is an excellent base for components that will later receive black KTL (e-coat) paint.
- Typical applications
- Screws, nuts, washers, brackets, clamps, hinges, stamped parts and steel components in general that need rust protection with a moderate to high bright finish.
Cross-sectionZn · 8–15 µm
Trivalent passivateColor and added protection
Zinc8 to 15 µm
Base steelCustomer part
Technical data
Technical specifications
- Base material
- Steel
- Coating thickness
- 8 to 15 µm
- Available finishes
- Full range of trivalent passivates: clear (blue), iridescent (yellow) and black
- Hexavalent chromium
- Free (one of the substances restricted under RoHS and ELV regulations)
- Corrosion resistance
- Validated by an external laboratory according to your customer's specification
- Plating method
- rack (hung, for delicate parts) and barrel (bulk, for high volume)
- Part size
- Parts under one meter in length
- Minimum lot
- 50 kg
Alkaline zinc
Zinc-nickel
Heavy phosphate
Coating thickness range for each process, in microns (µm). 1 µm is one thousandth of a millimeter.
FAQ
Quality control and FAQ
When should parts be rack or barrel plated?
Barrel plating processes parts in bulk inside a rotating drum, ideal for keeping costs down on fasteners and small parts. Rack plating hangs each part individually, designed for larger components or parts with critical tolerances that must not be impacted.
Does Gycrom apply KTL paint?
Not directly. At Gycrom we prepare the surface and apply the alkaline zinc coating according to the automotive specification. Once finished, the part is ready for your KTL supplier to apply the e-coat paint.
All processes
Zn-Ni · 8–15 % Ni
Zinc-nickel
A high-performance alloy (8% to 15% nickel) that retains its high corrosion resistance even after heat exposure, ideal for severe conditions with humidity or road salt.
View technical sheetZn/Mn PO₄ · 8–12 µm
Heavy phosphate
A non-metallic zinc and manganese phosphate coating designed specifically to retain lubricants and reduce wear between parts in contact.
View technical sheetQuote
Have a part that needs protection?
Tell us the material, the required specification and your monthly volume. We will review your drawings and prepare a technical proposal tailored to your needs.