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Chromating
aluminium

Corrosion protection & primer for the highest demands

Chromating – The proven method for protection & adhesion on aluminium

Chromating is a chemical surface treatment that coats aluminium and other metals with a thin protective layer. This so-called conversion layer improves corrosion resistance and serves as an optimal adhesive base for paintwork or bonded joints. Metalux offers various processes: Yellow chromating, transparent chromating and chromium (VI)-free chromating for environmentally friendly applications.

Chromating for corrosion protection & primer

The protective layer created during chromating is known as a passivation layer. It protects the metal from environmental influences and improves the adhesion of subsequent coatings.

Independent corrosion protection

No further surface treatment necessary

Perfect adhesion for paints & adhesives

Ideal basis for further refinements

Low electrical contact resistance

Suitable for conductive aluminium enclosures

Heat resistant up to 80 °C

Ideal for applications with moderate temperatures

Chromium VI chromating – Why is it still used?

Chromium VI-containing chromates have been replaced by chromium-free alternatives in many industries due to their harmful effects on health. The EU End-of-Life Vehicles Regulation and the RoHS Directive have prohibited the use of chromium VI for most civilian applications since 1 July 2007.

But why is it still used?

Chrome VI offers unrivalled corrosion protection in some specialist industries and is still permitted in certain high-security areas, including:

Aviation & aerospace

High-strength, corrosion-resistant aluminium components

Defence industry

Strict requirements for security and military technology

Special machine construction

Applications where maximum resistance is required

Aviation & aerospace

High-strength, corrosion-resistant aluminium components

Defence industry

Strict requirements for security and military technology

Special machine construction

Applications where maximum resistance is required

    Metalux only uses chromium VI where it is legally authorised and indispensable – and is developing sustainable alternatives in parallel.

    Chromium VI-free chromating as an environmentally friendly alternative

    Since conventional chromating with chromium VI is no longer permitted in many areas, Metalux offers environmentally friendly alternatives based on chromium III compounds.

    The SurTec 650 ChromitAL process is a fully-fledged replacement for yellow chromating and fulfils all important requirements.

    SurTec 650 ChromitAL produces a slightly iridescent, slightly yellowish, reddish to blue layer – depending on the aluminium alloy.

    Excellent corrosion protection

    Resistant protective layer against environmental influences

    Electrical conductivity

    Optimal for enclosures with EMC shielding

    Excellent paint & adhesive adhesion

    Perfect base for further coatings

    RoHS & REACH compliant

    Complies with all EU environmental regulations

    Properties of chromate layers

    Chromated surfaces offer a unique combination of protection and functionality:

    Corrosion protection without additional sealing
    Conductive & shielding for electronic applications
    Ideal as an adhesive primer for paintwork & bonding
    Heat resistant up to 80 °C

    Areas of application for chromating

    Chromated aluminium components are in demand in many industries:

    Aviation & aerospace

    Lightweight, corrosion-resistant aluminium components

    Automotive industry

    Adhesion promoter for coatings & adhesive bonds

    Electrical engineering & EMC enclosures

    Low contact resistance for conductive connections

    Mechanical engineering

    Protective coatings for mechanical components

    Aviation & aerospace

    Lightweight, corrosion-resistant aluminium components

    Automotive industry

    Adhesion promoter for coatings & adhesive bonds

    Electrical engineering & EMC enclosures

    Low contact resistance for conductive connections

    Mechanical engineering

    Protective coatings for mechanical components

      Dimensions & technical options

      Metalux offers chromating for a wide range of workpiece sizes and alloys. Our systems enable flexible solutions for a wide range of requirements.

      Contact us for special requirements or customised solutions.

      What component sizes can be chromated?

      Procedure / ProcessingLength in mmWidth in mmDepth in mm

      Chromic acid and hard and sulphuric acid anodising, yellow and transparent chromating, chromium (VI) free chromating
      4600
      420
      1300
      All product window sizes

      FAQ about chromating

      Why is chromium VI still used?

      Chrome VI offers unsurpassed corrosion protection and is still legally permitted in special industries such as aviation, aerospace and defence.

      What is the difference between chromium VI and chromium III chromating?

      Chromium III chromates are more environmentally friendly and fulfil modern regulations, but offer slightly less corrosion protection than chromium VI.

      Is a chromated surface electrically conductive?

      Yes, chromate layers have a low contact resistance and are suitable for conductive connections, e.g. in electrical engineering.

      How long does a chromate coating last?

      The durability depends on the environmental conditions. In dry environments, chromate coatings offer long-term protection, while additional sealing may be useful in aggressive media.

      Can chromated surfaces be painted?

      Yes, chromating is an ideal pre-treatment for paintwork and improves the adhesion of paints and coatings.