What are Conversion Coatings?
Chromate conversion coating is a widely used surface treatment method in the metal finishing industry, also known as chem film. The process involves treating metal surfaces with chromate solutions to create a protective layer that enhances corrosion resistance and improves paint adhesion. The coating is commonly applied to aluminum and other lightweight metals to provide an extra layer of protection against environmental factors and extend the lifespan of the material.
Chromate conversion coatings are widely used in industries such as aerospace, automotive, and electronics for their ability to improve the durability and performance of metal components. The thin coating makes it especially useful for aircraft hulls and components, as it adds little weight.
Chromate conversion coatings are typically applied via immersion in a chemical tank or bath, or by brushing or spraying.
For details on the conversion coating process, please see our article “What is Alodine / Chem Film / Chromate Conversion Coating?”
Trivalent Chromium for Conversion Coating
Historically, manufacturers used hexavalent chromium as the industry standard for chromate conversion coatings. However, hexavalent chromium is a known carcinogen and environmental pollutant. These hazards prompted researchers to identify trivalent chromium as an effective, safer alternative for chromate conversion coating.
Trivalent chromium compounds have low toxicity and, unlike hexavalent chromium, cannot enter living cells easily. Trivalent chromium is increasingly being used for conversion coating due to its reputation as a safer and more environmentally friendly option.
Today, Best Technology partners with Chemeon to offer a family of industry-leading trivalent chromium conversion coating chemicals.
BestSolv-CF CHEMEON® TCP-HF
TCP-HF is a trivalent chromium conversion coating that offers corrosion protection, coating durability, and strong bonds for paint and adhesives, all at a cost similar to hexavalent chromates. Originally designed for aluminum, it has been successfully tested on other metals such as zinc nickel, zinc alloy, and cadmium plating. It is specifically engineered for chemical conversion and anodizing seal purposes.
The initials in TCP-HF stand for Trivalent Chromium Pretreatment – Hex-Free
BestSolv-CF CHEMEON® eTCP® Powder
The related product, eTCP®, offers the advantages of TCP-HF, with the addition of dye that allows quality inspectors to distinguish easily between treated and non-treated surfaces. Surfaces treated with eTCP® have a purplish color that is distinct from untreated surfaces.
The initials in eTCP® stand for Enhanced Trivalent Chromium Pretreatment.
Color Comparison of Conversion Coatings
Benefits of Trivalent Chromium for Conversion Coating
Besides enhancing worker safety, trivalent chromium conversion coatings also provide the benefit of requiring fewer processing steps and lower temperatures, which in turn reduce evaporative losses. Both TCP-HF and eTCP® demonstrate equal or superior performance compared to hexavalent chrome coatings in salt-spray tests for corrosion resistance.
Trivalent Chromium Conversion Coating Comparison
| BestSolv-CF CHEMEON® TCP-HF | BestSolv-CF CHEMEON® eTCP® Powder | |
| Process | Trivalent chromium | Trivalent chromium |
| Applications |
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| Substrates |
| Light metals such as 2024 aluminum |
| Color | Clear | Purplish, for easy identification of coated parts |
| Properties |
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| Application Methods | Immersion. Spray. | Liquid for use in immersion, spray, and brush applications on bare aluminum. |
| Corrosion Resistance |
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| Temperature Exposure |
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| Product Advantages |
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| Industries Served |
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| Industry Specifications and Standards | MIL-DTL-81706. MIL-DTL-5541 Type II. MIL-C-5541 Class 1A and Class 3. ROHS. REACH. WEEE. ELV. OSHA, ASTM B921. QPL. | MIL-DTL-81706B and MIL-DTL-5541F Type II, Form II, Class 1A and Class 3, Method C for immersion method. Qualified Products List (QPL/QPD) under QPL-81706. |
Trivalent Chromate Conversion Coating Options
Trivalent chrome coatings TCP-HF and eTCP are available from Best Technology in these formats:
- TCP-HF – 55 gallon drum.
- eTCP RTU (ready-to-use liquid) – 5 gallon pail or 55 gallon drum.
- eTCP Powder – Sold by the pound, 2-pound minimum.
Common Applications for Chromate Conversion Coatings
The most common application of chromate conversion coating is in the aerospace industry, where it is used to protect aircraft components from corrosion and enhance their paint adhesion. It is also widely used in the automotive industry for coating components such as brake calipers, wheels, and other metal parts to improve their durability and appearance.
Additionally, chromate conversion coating is utilized in the construction industry for protecting architectural elements and metal structures from rust and degradation. It is also commonly used in electronic applications to provide a conductive surface for components and improve their solderability. With its wide range of applications, chromate conversion coating plays a vital role in enhancing the performance and longevity of various metal products across different industries.
Conversion Coating Equipment
Best Technology offers industry-leading equipment for conversion coating. Visit our Chem Film Tank Line page to learn about equipment for chromate conversion coating operations.
Trivalent Conversion Coating Price and Ordering
Please contact our chemical sales department for a quote on conversion coating chemistry by clicking the “Get a Quote” button, or call 612-392-2414, ext. 2