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Passivation of aluminium at Mifa

Passivating aluminium provides long-term corrosion protection and durability, serving as the key to aluminium preservation

At Mifa Aluminium, we offer various surface treatments, including passivation. Passivation contributes to improved corrosion resistance, thereby extending the lifespan of the aluminium product. This chemical process provides various properties such as maximum layer thickness, electrical resistance, colour, and standards. Learn more about the possibilities of aluminium passivation at Mifa on this page.

What is passivation?

To discuss the various possibilities of passivation at Mifa, let’s first explain what passivation is. As you may know, aluminium is a base metal that spontaneously oxidizes in contact with oxygen and moisture from the air. This results in the formation of an oxide layer of aluminum oxide on the aluminium surface. While this natural oxide layer provides limited protection against corrosion under non-aggressive conditions, it is thin and vulnerable.

However, the natural oxide layer is thin and vulnerable. Damages to the natural oxide layer reduce corrosion resistance because there is no completely closed oxide layer on the metal. If passivation does not occur or is incomplete, the aluminium is insufficiently protected against corrosion. Passivation, in this context, involves the formation of a protective layer (chromate or conversion layer) that forms a bond with the aluminium.

The advantages and disadvantages of passivating aluminium

By making the surface of a workpiece passive, corrosion is prevented. The formed conversion layer also serves as a good foundation for applying various types of paint. This layer is electrically conductive with a constant resistance, providing the following benefits:

  • Improvement of corrosion resistance;
  • Basis for (wet) coating systems;
  • Constant resistance for electrical conduction.

Passivation is a chemical process and can be applied through immersion or spraying. The process is contactless, and the workpiece can often be treated in baskets, providing cost advantages. The layer complies with various standards and is also approved for the aviation industry. The mechanical load capacity of this layer is very limited, and the layer is not self-healing.

The possibilities of passivation

Surtec 650 is a Chromium VI-free passivation; the active substance is Chromium III, and it is RoHS compliant. Through additional steps in the pre-treatment, the application is possible for almost all alloys, including both wrought and cast alloys. Surtec® 650 is also known as Cr6+ free passivation. This application is a chemical treatment of the metal surface where a chromate layer or conversion layer is formed. During chromating, the top layer of aluminium is converted into a different aluminium compound. After painting, the chromate layer will provide good, lasting protection against under-corrosion.

Maximum layer thickness Less than 1 µm, without affecting dimensions
Corrosion protection Maximum 336 hours salt spray test according to DIN EN ISO 9227 ASMT B-117
Electrical resistance Less than 32.25 mΩ x cm2
Colour Light iridescent
IMDS number 30429267
Maximum dimensions 3,600 x 500 x 850 mm (max. 500 Kg)
General standards MIL-DTL-81706-B and MIL-DTL-5541-F

Certifications

At Mifa, we hold various certifications, including ISO 9001, and ISO 14001. Additionally, Mifa Surface Treatment, like Mifa, is certified with the AS9100 certificate for the aerospace industry. This certification provides evidence that the production and business facilities of Mifa comply with the high-quality standards applicable to the aerospace industry.

Passivation of aluminum profiles as a sustainable solution

Aluminium passivation is a process used to enhance the corrosion resistance of aluminium profiles. A thin oxide layer is applied, protecting the underlying metal from corrosion, resulting in prolonged life and structural integrity of the aluminum. This provides various sustainable solutions:

  • Extended lifespan: by applying aluminium passivation, we extend the lifespan of our aluminium extrusion profiles. This means the profiles need to be replaced less frequently, reducing the demand for new raw materials and energy for production.
  • Energy efficiency: passivating aluminium contributes to energy efficiency as the oxide layer on the surface reduces heat conduction. This can contribute to preserving energy in applications where heat loss is a concern.
  • Reduced environmental impact: since oxidized aluminium is more resistant to corrosion, there is less need for aggressive cleaning and maintenance procedures that can cause environmental damage. This leads to a lower environmental impact of aluminium production and use.
More about sustainability

Unique Bright-dip on the profiles of SodaTASTE

Together with our customers, we strive to produce the best end product. Our engineers are eager to engage in a conversation with you to elevate your end product to the next level. With one of our knowledge partners, SodaTASTE, we have anodized aluminum bottles in color. During the design phase, various steps were taken to create a unique product. A great example of how Mifa employs co-engineering to collaborate with customers during the design phase.

More about this case study

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Manager Surface Treatment

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