Ceramic

Ceramic coatings are inorganic, nonmetallic coatings that act as a barrier between the corrosive environment and the base material being protected. They often consist of an oxide film that is formed on the surface of a metal by chemical reaction, which can occur naturally on some metals; however, more effective corrosion resistant coatings can be produced. Ceramic coatings are especially useful for providing high temperature corrosion protection. Examples of ceramic coatings include chromate films and phosphate coatings. 

Chromate Films

Although chromate films provide a significant improvement in the corrosion resistance of a metal substrate, it is mainly used as a precursor to other coatings and paints. Chromate coatings are often used on steel, copper, aluminum, magnesium, nickel, silver, tin, and cadmium substrates.89 Thin chromate films can be applied by immersion, spraying, or brushing.

Phosphate Films

Metal phosphate coatings, which form on the surface of a metal when subjected to the appropriate environment by chemical reaction, are used mainly for corrosion protection, but in addition, they provide a good surface for other coatings to adhere to. When combined with corrosion inhibitors or other coatings, the corrosion protection is improved significantly. Phosphate coatings are usually applied either by spraying for larger components or by immersion in solution baths. Immersion is the preferred method as a more homogeneous coating is produced.