Electrogalvanising is the most common electrolytic coating for steel.
The resulting coating provides reasonable corrosion protection and a pleasing appearance at low cost.
The coating is also often used underneath painting to improve the corrosion properties and adhesion of the paint.
Electro-galvanising:
- We use an alkaline cyanide-free zinc bath
- Electro-galvanising with drum and suspension techniques
- Maximum dimensions of the piece to be galvanized: 2000x1000x400
The passive voice:
- blue passivation, Cr3+
- black passivation, Cr3+
- thick film passivation Cr3+
- after-box (sealer)
- All passivation and after-treatments RoHS compliant
Electrogalvanizing standards:
- Electroplated coatings of zinc with supplementary treatments on iron or steel (ISO 2081:2018)
- Fasteners – Electroplated coatings (ISO 4042:2018)
- Metallic coatings – Electroplated coatings of zinc and zinc alloys on iron or steel with supplementary Cr(VI)-free treatment (ISO 19598:2016)
- Corrosion tests in artificial atmospheres.
Salt spray tests (ISO 9227:2017)
Zinc and electro-galvanising provide cathodic protection to the steel, so small scratches in the coating do not cause immediate rusting of the steel.
Corrosion resistance modelling determines the time that the coating must last before red rust appears on the piece.
The most common modelling is the neutral salt spray test according to ISO 9227:2006.
Most commonly, electroplating of zinc is passivated in order to slow down the oxidation of zinc as much as possible.
The passivation therefore protects the zinc from white rust and the zinc itself protects the substrate from red rust.
Nowadays, especially for passivations under the new RoHS and ELV Directives, the passivation is often used to protect the metal against the so called “tin plating”.
sealer, which achieves a significant improvement in corrosion values.
The resistance of the coating against white corrosion is determined in the final test according to how long the passivation (and post-coating) can withstand salt spray.
The drawings may indicate the required durations, e.g. 200/400 h, for white rust and red rust.
Today, almost all baths in use are either acidic or alkaline.
Acid zinc is more lustrous in appearance than alkaline.
The ability of an alkaline bath to spread the zinc coating evenly over the different parts of the piece is much better than an acid bath.
With few exceptions, the cyanide bath has been phased out.
The basics of zinc plating
Galvanising is the process of coating the surface of a metal with a layer of zinc to protect it from corrosion and give it a more pleasing appearance.
Galvanising, or zinc coating, gives a brighter and more even layer than hot-dip galvanising.
The advantage of hot-dip galvanising is a thicker zinc layer and therefore corrosion protection.
Electrogalvanised parts are usually passivated and post-cast, which clearly improves the corrosion resistance of the part.
Galvanising gives the piece better properties at a lower cost.
The process is well suited to most iron or steel parts.
Zinc plating according to your needs
Thanks to our long experience and the equipment we have at our disposal, electrogalvanising can be carried out very cost-effectively, whether for small or large production batches.
Contact us – we’ll be happy to tell you more.
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