Chromate Conversion Coatings for Aluminum per MIL-DTL-5541F

Alodine, also known as chromate conversion coating, is a highly effective surface treatment widely used across various industries to enhance the corrosion resistance of metals, particularly aluminum and magnesium alloys. This chemical process is crucial in the aerospace, automotive, military, and electronics sectors, where high performance and durability are paramount. Alodine forms a protective, corrosion-resistant layer that improves paint adhesion and extends the lifespan of components exposed to harsh environments. Its benefits include excellent conductivity, ease of application, and compliance with stringent industry standards, making it an ideal solution for companies seeking to improve the reliability and performance of their metal products. Our Alodine is both ROHS compliant and hexavalent chromium-free, ensuring it meets the highest environmental and safety standards. Whether for aircraft parts, automotive components, or electronic enclosures, Alodine ensures superior protection and longevity.

Specifications:

MIL-DTL-5541F - The chemfilm coating process is often governed by the commonly used MIL-DTL-5541 standard, which specifies different types and classes of chem film coatings.

ASTM B117-19 - Salt spray testing

Classes

Unlike anodizing, Alodine coatings offer electrical conductivity for aluminium parts, when applied according to Class 3 of the MIL-DTL-5541F standard..

Alodine, a type of chromate conversion coating, is classified into different types based on its performance characteristics and intended applications. The most common classifications are Class 1A and Class 3, each serving distinct purposes:

Class 1A- Chromate Conversion/Chem Film/Alodine

Class 1A is designed for maximum corrosion protection and paint adhesion. It provides a thicker and more robust coating, making it ideal for applications where high durability and long-term protection are essential. This class is often used in aerospace and military applications, including aircraft structures, shock absorbers, landing gear, and other critical components. The primary benefits of Class 1A Alodine include:

  • Superior Corrosion Resistance: Offers excellent protection against harsh environmental conditions and chemical exposure.

  • Enhanced Paint Adhesion: Provides a reliable base for subsequent painting, ensuring long-lasting and durable finishes.

  • High Durability: Suitable for components that require long-term protection and withstand severe service conditions.

Class 3- Chromate Conversion/Chem Film/Alodine

Class 3 is formulated for applications where electrical conductivity is critical. It provides a thinner coating compared to Class 1A, maintaining the conductive properties of the base metal. This class is commonly used in the electronics and electrical industries for components such as connectors, housings, and grounding surfaces. The primary benefits of Class 3 Alodine include:

  • Electrical Conductivity: Ensures that the coated parts retain their conductive properties, making it suitable for electrical and electronic applications.

  • Sufficient Corrosion Protection: Provides adequate protection against corrosion while maintaining conductivity.

  • Light Coating: The thinner coating does not interfere with the electrical performance of the components

Properties Summary

·         hexavalent chromium free passivation for aluminium

·         suitable as post-treatment of anodic coatings

·         suitable as conversion coating of magnesium

·         liquid concentrate, based on trivalent chromium

·         excellent bare corrosion protection comparable to hexavalent passivation’s

·         also works on alloyed and casted aluminum

·         suitable as pretreatment before lacquering, powder coating and gluing and approved by GSB and QUALICOAT

·         easy to handle in immersion, spray and wipe application

·         produces an iridescent, faintly blue to tan and visible layer

·         complies with LN 9368-3 ID-number 1108 meets or exceeds MIL-DTL-81706B and MIL-DTL-5541F for bare corrosion (336 h in NSS per ASTM B-117, respectively, DIN EN ISO 9227)

·         low contact resistance: < 5000 μOhm per square inch per MIL-DTL-81706B