Chromate Conversion Coatings

MIL-DTL-5541F  Type I, Class 1A or 3, Yellow Chromate Conversion

irridite-alodineAlso referred to by trade names such as Chemtreat, Chemfilm, Iridite® and Alodine®).

Yellow Chromate Conversion is a procedure that chemically applies a protective coating on aluminum through immersion.

The two classes of Chromate Conversion:

Class 1A coatings are thicker and intended to provide better corrosion prevention when left unpainted as well as to improve adhesion of paint finish systems on aluminum alloys.
Class 3
coatings are intended for use as a corrosion preventative film for electrical and electronic applications where lower electrical resistance is needed or required.

The benefits to chemically treating aluminum:

  • Good corrosion protection
  • Conductive surface
  • Good primer for painting
  • Adds no weight
  • Maintains pre-process dimensions