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Mil Spec: MIL-DTL-5541F
Classification. The chemical chromate conversion coatings are of the following types and classes.Types. The chemical conversion coatings are of the following types.
Type I – Compositions containing hexavalent chromium
Type II – Compositions containing no hexavalent chromium
Classes. The materials, which form protective coatings by chemical reaction with aluminum and aluminum alloys, are of the following classes
Class 1A – For maximum protection against corrosion, painted or unpainted.
Class 3 – For protection against corrosion where low electrical resistance is required.
ASTM Designation: B 449
Chromates on AluminumClassification of Chromate Coatings
|Class*||Appearance||Coating Mass per Unit Area, g/m2||Corrosion Protection|
|1||Yellow to brown||0.4 to 2||Maximum corrosion resistance generally used as final finish|
|2||Colorless to yellow||0.1 to 0.4|
Moderate corrosion resistance, used as a paint base and for bonding to rubber.
3 Color less<0.1 Decorative, slight corrosion resistance, low electrical contact resistance.4Light green to green0.2 to 5Moderate corrosion resistance, used as a paint base and for bonding to rubber
* No relationship exists between class numbers and degree of corrosion resistance. Class numbers have been assigned on the basis of traditional usage and for compatibility with national standards.
Silvex Inc. offers several options for chromate and chemical film finishing. To learn more about our processes, please contact us today.