Aluminum
Aluminum Surface Treatment
Aluminum and its alloys are widely used in industry because of their low density, mechanical strength, and inherent corrosion resistance. Depending on the application, however, their surface properties may need to be improved.
Surface treatment of aluminum can, in particular , improve corrosion protection, wear resistance, electrical conductivity, coating adhesion, or certain functional properties of the part.
The choice of treatment depends on many factors: aluminum alloy, part geometry, operating environment, mechanical and electrical stresses, desired thickness, dimensional tolerances, and specification requirements.
At Wipelec, we perform various surface treatments on aluminum and aluminum alloys, including Surtec, Alodine, electroless nickel plating, copper plating, and silver plating.
Why treat the surface of aluminum?
Aluminum naturally forms a thin oxide layer when exposed to air. This layer contributes to its corrosion resistance, but it does not necessarily meet the requirements of all industrial applications.
Improving corrosion resistance
In certain environments, aluminum’s natural protection is not sufficient. A chemical conversion treatment enhances the surface’s protection while preserving the material’s desired properties.
Maintain or improve electrical conductivity
In electrical and electronic applications, the treatment must ensure that the requirements for conductivity and electrical contact are met .
Increase wear resistance
Parts subject to friction, repeated contact, or certain mechanical stresses may require a surface with increased wear resistance.
Preparing a Room Before Painting or Applying a Finish
Some chemical conversion treatments are also used as surface preparations to improve the adhesion of a subsequent coating and provide protection against corrosion.
Meeting Industrial Specifications
In the aerospace, defense, electronics, and mechanical engineering sectors, surface treatment is often an integral part of a part’s technical specifications.
Surface Treatments Performed by Wipelec
Several processes are compatible with aluminum and its alloys. At Wipelec, we offer the following treatments, selected based on your project’s requirements.
Surtec
Surtec is an alternative to Alodine, formulated without hexavalent chromium. Compliant with RoHS and REACH directives, it offers comparable corrosion protection and an excellent primer for paint. Surtec is the preferred choice for projects subject to strict environmental and regulatory requirements, particularly in the aerospace and professional electronics industries.
Electrolytic nickel plating on aluminum
Electrolytic nickel plating can be applied to aluminum provided that a specific pretreatment (zincate) is performed. It provides high hardness, excellent wear resistance, and a perfectly uniform coating, even on complex geometries. This process is preferred for technical mechanical parts used in aerospace or optics.
Copper plating
Electrolytic or chemical copper plating on aluminum also requires a preliminary activation step. It is used as a conductive undercoat, in preparation for another plating layer (nickel, silver, gold), or to improve the electrical conductivity of electrical connectors.
Silver plating
Silver plating on aluminum is less common but can still be achieved with the proper pretreatments. It is intended for demanding applications where high electrical conductivity and resistance to oxidation are priorities: waveguides, radio frequency connectors, and satellite equipment.
Alodine 1200
Alodine 1200 is a chemical conversion coating specifically developed for aluminum. It forms a chromate-based conversion coating that effectively protects against corrosion while improving the adhesion of subsequently applied organic paints and coatings. It is the standard process in the aerospace and defense industries, particularly for parts that comply with MIL-DTL-5541 specifications (developed by the U.S. Department of Defense).
How do you choose the right finish for your aluminum part?
The choice of process depends first and foremost on the intended function. There is no single treatment suitable for all aluminum parts. Other criteria must also be taken into account: alloy type, part dimensions, production run, and dimensional tolerances to be met.
For precision-machined parts, certain surface treatments can cause slight dimensional changes, a factor we take into account as early as the design phase.
| Surface treatment | Technical Specifications |
|---|---|
| Alodine 1200 or Surtec | Corrosion protection and paint adhesion |
| Surtec | Compliance with the ban on hexavalent chromium (RoHS, REACH) |
| Electroless nickel plating | High wear resistance and hardness |
| Silver plating or copper plating | Maximum electrical conductivity |
| Chemical or electrolytic copper plating | Primer before further coating |
| Alodine 200 | Aeronautical Specifications (MIL-DTL-5541) |
Surface treatment based on the aluminum alloy
Not all aluminum alloys react the same way during surface treatment. The alloy’s composition, additives, metallurgical condition, and manufacturing history can influence the part’s behavior during preparation and treatment.
Among the alloys commonly found in industry are the following families:
- 2000, including 2017 and 2024
- 5,000, including 5,083 and 5,754
- 6000, including 6060, 6061, and 6082
- 7000, including 7075
The treatment must therefore be determined based on the exact aluminum grade and the part's requirements.
Do you know the alloy but aren't sure which heat treatment to use? Please send us the material reference and describe your requirements via our contact form.
In which industries is aluminum processing used?
Aluminum surface treatment is used in many industries.
Aeronautics
The parts must meet high standards for corrosion protection, weight, mechanical properties, and compliance with specifications.
Defense
Components may be exposed to harsh environments and subject to specific requirements for protection and durability.
Electronics
Conductivity, contact quality, and surface stability are important criteria for many parts.
Industrial Mechanics
These treatments can be used to improve a part's wear resistance, corrosion protection, or functional properties.
Why choose Wipelec for aluminum surface treatment?
At Wipelec, we perform surface treatments on aluminum following our machining processes to achieve the results requested by our customers. Our machinery and the expertise of our teams enable us to offer all major surface treatment processes to make the aluminum more durable: Alodine, Surtec, electroless nickel plating, electroless copper plating, and tin plating.
Aluminum pretreatment
The success of a surface treatment on aluminum depends largely on the quality of the pretreatment. Without thorough preparation, the coating may be uneven, fail to adhere properly, or even blister in the short term.
Degreasing
Removal of cutting oils (liquids used during metal machining), greases, and organic residues left behind by machining
Stripping
Removal of the natural, uneven, and poorly adhering alumina layer
Deoxidation
Removal of fine particles and residual intermetallic phases (areas composed of a mixture of metals)
Want to learn more about aluminum surface treatment?
Do you have questions about aluminum surface treatment? Find answers to the most frequently asked questions here!
What is the best anti-corrosion treatment for aluminum?
The Alodine 1200 remains the industry standard, particularly for aerospace and defense applications requiring compliance with MIL-DTL-5541.
Surtec provides equivalent protection without hexavalent chromium and is now the standard choice for projects subject to the RoHS and REACH directives.
The choice depends primarily on the specifications set forth in your requirements document.
Alodine 1200 or Surtec: Which one should you choose?
Both processes serve the same purpose: corrosion protection and improved paint adhesion on aluminum.
The Alodine 1200 is the preferred choice when an aviation standard explicitly requires it.
Surtec is selected when environmental regulations or your company’s CSR policy require a formulation free of hexavalent chromium.
Can aluminum be nickel-plated?
Chemical nickel plating on aluminum is entirely feasible. However, it requires a preliminary zincate treatment to ensure the deposit adheres properly. The result offers high hardness and excellent wear resistance, making it particularly suitable for precision mechanical and optical components.
Does surface treatment affect the dimensions of my aluminum part?
Depending on the process, the thickness of the coating ranges from a few microns (Alodine, Surtec) to several tens of microns (electroless nickel plating, copper plating).
This allowance must be accounted for during machining.
At Wipelec, we take these constraints into account in our technical designs to ensure that the final tolerances meet your specifications.
What aluminum alloys do you process?
We process all standard series: 1000 (pure aluminum), 2000 (copper alloys), 5000 (magnesium), 6000 (Al-Mg-Si, such as 6061 and 6082), and 7000 (high-strength alloys, such as 7075).
Each series requires specific pretreatment parameters, which we tailor to your part.
Surface treatment for aluminum is a very broad topic; please feel free to contact us so we can assess the feasibility of your project.
Our various processes
Would you like to learn more about our surface treatments? Find out more and explore all our solutions!