Chemical Conversion Coating

At a Glance

Chemical conversion coatings are coatings for metals where the part‘s surface is subjected to a chemical or electro-chemical process by the coating material which converts it into a decorative or protective substance. Examples include chromate conversion coatings, fluorozirconates, fluorotitanates, sol gels, phosphate conversion coatings, bluing, black oxide coatings on steel, and anodizing. They are used for corrosion protection, decorative color, adhesion promoters, and electrically conductive coatings.

Elemental metals (except precious metals), including their alloys, usually spontaneously react with the medium to form compounds and return to their mineral state under normal conditions. This is the reverse process of metallurgy. This process is called metal corrosion. Sometimes this process does not go on and will stop very quickly, because at this time, the compounds formed by the metal and the medium accumulate on the metal surface, and this layer of dense metal compounds forms a "film". At this time, the metal seems to wear a coat that prevents further contact between the metal and the medium, especially if the compound is poorly soluble in water. The chemical conversion film is designed based on this principle.