This coating is often referred to as “Chem Film”, “Alodine”, “Iridite”, or “Conversion Coat”. Chromate Conversion Coating is a chemical process that forms a thin, protective layer on the surface of aluminum. Commonly used as an undercoat to promote adhesion and guard the base metal from corrosion. On a molecular level, it is gel-like and has self-healing properties. This coating also helps to retain electrical conductivity.
The Restriction of Hazardous Substances Directive (RoHS) was adopted by the European Union in 2003. This restricts importing of products containing toxic materials- including Lead, Mercury, Cadmium and Hexavalent Chromium. The industry has since developed RoHS compliant chromate conversion coatings by substituting Trivalent Chromium.
These coatings meet all performance requirements and can be found on the federal standard Qualified Product List, MIL-DTL-81706. Commonly used as an undercoat to promote adhesion and guard the base metal from corrosion. This coating also helps to retain electrical conductivity.
|PROCESS||TANK SIZE||NADCAP CERTIFIED|
|Conversion Coating (Ty I)||14' x 6' x 4'||No|
|Certified Conversion Coating (Ty II)||7' x 4' x 3'||Yes|
|RoHS Compliant Conversion Coating (Ty II)||7' x 4' x 3'||No|
The following are examples of finishing callouts that would be found on a print or purchase order and would indicate specific anodizing processes for a metal finisher like Pilkington Metal Finishing. These guides are meant for use by engineers and purchasing agents.
Note: If surfaces to be coated are not specified, all surfaces will be coated by default.
The following is a list of applicable specifications for conversion coating along with their title and issuer. Pilkington commonly processes to these specifications and is capable of processing to many more upon request.
|BAC5719||Chemical Conversion Coatings for Aluminum and Aluminum Alloys||Boeing|
|MIL-C-5541||Chemical Conversion Coatings on Aluminum and Aluminum Alloys||Industry Standard|
|MIL-DTL-5541||Detail Specification Chemical Conversion Coatings on Aluminum and Aluminum Alloys||Industry Standard|
Q: I have a product to be coated, do you recommend anodize or conversion coating as pretreatment?
Conversion Coating of aluminum provides a fantastic sub-surface treatment to a paint job. Iron Phosphate would be used on steel parts. Anodizing is typically used as a final finish. Both are rust inhibitors.
Q: What materials can be conversion coated?
We recommend Aluminum and Magnesium.
Q: How does Conversion Coating help with electrical conductivity?
Anodized aluminum is not electrical conductive and will not ground well. Conversion coating over aluminum is electrically conductive and will ground well.
Q: Why would I use RoHS compliant conversion coating?
Typically used in European and Asian contries, RoHS is a requirement. RoHS compliant has to do with chrome content. Chromate conversion coating is great, hexavalent chrome vs. trivalent chrome.