For Chemical industry, Power plants and Aerospace industry
Diffusion coatings is protected the high temperature corrosion of the components by increasing their oxidation or corrosion resistance in the chemical industry, power plants and the aerospace industry.

They are typically deposited by a pack cementation process, which consists of introducing the substrate material into a powder mixture containing the desired alloying elements to be deposited. Heated at high temperature, in an inert atmosphere, diffusion of protective elements into the substrate occurs, leading to the formation of the coating.

From- http://kwi.dechema.de/