Chromate Conversion Coating
Chromate conversion coatings are created through a passivation process. This method renders the coated surface structure chemically inactive. A complex metal-chrome molecule film then forms around the metal, which eventually forms into a continuous gelatinous coating. This type of gelatinous coating effectively eliminates the chemical reaction process, which is what causes corrosion. Chromate conversion coatings provide continuous corrosion protection to the metal on which it is applied.
Chemical films are used for corrosion resistance and a paint base. When electrical conductivity and corrosion resistance are both required, chemical film is a good choice. The coating comes in both iridescent yellow and clear colors; however, it should be noted that the yellow gives superior corrosion resistance. The lighter color gives lower electrical resistance. It should also be noted that chemical film is fragile directly after processing and a 24-hour waiting time before handling the parts is preferable.