Copyright 2009 Eastern Plating Company Website Design by Graphical Media Services What Is Chemical Conversion Coating? Chemical Conversion Coating comes under different names like chem film, iridite,etc. A chemical conversion coat is a very thin protective coating of aluminum oxide and other chemical compounds. Although there are several kinds of chemical conversion coatings for aluminum, the most common are produced from a chromate fluoride bath. Chemical conversion coats can be used for mild corrosion protection although they are normally used as an undercoating and base for organic finishes or adhesive bonding. These coatings offer no resistance to wear or abrasion and do not provide nearly the corrosion protection of anodic coatings. The main attraction of these coatings is the economy and the speed with which they can be applied to the substrate. Although there are others, the most common specification used for chemical conversion coating is MIL-DTL-5541. This is available in two types in combination with 2 classes. Lets talk about types. type one is the “classic” mixture that includes a hexavalent chrome. With the introduction of the European RoHS Regulation and a general awareness of the dangers of hexavalent chrome Type II was created. Type II offers the same treatment using a non-hexavalent chrome mix. To read more about the RoHS requirements follow this link: www.rohs.gov.uk/ Type I, Class 1a - Containing Hexavalent Chrome - For maximum corrosion resistant, for surfaces to be painted or left unpainted. Type I, Class 3 - Containing Hexavalent Chrome - For protection against corrosion where lower electrical resistance is required. Type II, Class 1a - Non-Hexavalent Chrome - For maximum corrosion resistant, for surfaces to be painted or left unpainted. Type II, Class 3 - Non-Hexavalent Chrome - For protection against corrosion where lower electrical resistance is required. Chemical Conversion Coating USEFUL AND INFORMATIVE LINKS www.astm.org - Search and purchase ASTM Specifications www.sae.org - Search and purchase AMS Specifications. www.finishing.com - Finishing information and forums assist.daps.dla.mil/quicksearch - Search and download Military Specifications. www.anodizing.org - find valuable information about the metal finishing process of aluminum anodizing