Chromate conversion coating services

Sometimes referred to by specific proprietary product names, such as “Iridite”, “Chem Film”, “Chemical Film” or “Alodine”, chromate conversion coatings provides a surface treatment alternative to electroplating for finishing metal parts composed of magnesium, aluminum or aluminum alloys in order to provide better corrosion resistance. An acid or acids in the conversion coating typically dissolve some of the metal on the surface of the part, reacting to form new chromium compounds. Chromate applied to the surface of the part undergoes a chemical reaction and produces a microscopic yellow-greenish tinted surface layer of corrosion-resistant material. The specific formulations utilized by different coating manufacturers vary in composition.
Chromate Conversion Coating (also commonly referred to as Chemical Film, Chem Film, Alodine or Iridite) converts the surface properties of the substrate (typically aluminum or magnesium) as compared to plating which applies a coating onto the surface of the substrate. Chromate provides excellent corrosion resistance, is conductive and results in no measureable buildup (0.00001″- 0.00003″) on the parts. Chromate coatings are the most widely used coating for corrosion protection of Aluminum and Aluminum alloys minimizing surface oxidation. It is commonly used for an undercoat for paint or adhesive applications due to the excellent bonding properties it provides. Class 1A coatings give maximum corrosion protection with the highest electrical surface resistance while class 3 coatings have lower corrosion protection and provide lower electrical surface resistance.
Advanced Surface Technologies applies both standard hexavalent (clear and yellow) and RoHS compliant Trivalent (TCP) to Aluminum and Magnesium alloys. Both Hexavalent and Trivalent films at Advanced Surface Technologies have passed initial 336 hour salt spray testing and are subject to monthly 168 hour salt spray testing as well as paint adhesion testing conforming to all specifications. MIL-C-5541E, MIL-DTL-5541F, ASTM B 449-93 (2004), AMS 2473G, AMS 2474D and MIL-DTL81706B.
The Trivalent Chromium Process (TCP) provides a non hexavalent chrome coating compliant with RoHS, ELV and WEEE directives. It compares favorably with the hexavalent coatings providing a conversion coating that fulfills the corrosion, paint and electrical requirements of the different specifications. Advanced Surface Technologies extensive experience with the chromate process enables us to effectively process cast and all the different wrought alloys with alloy specific pretreatment chemistries.