Diffusion Coatings,Diffusion Coatings,Diffusion Coatings,Diffusion Coatings,Diffusion CoatingsDIFFUSION COATINGS are deposited either by heating the components to be treated in contact with the powder coating
material in an inert atmosphere (solid-state diffusion) or by heating them in an atmosphere of a volatile compound of the
coating material (out-of-contact gas-phase deposition, or chemical vapor deposition). Solid-state diffusion methods
include pack cementation, which is the most widely employed diffusion coating method and the process described in most
detail in this article, and various slurry or powder-paint methods of coating metal parts and assemblies. The most widely used coatings are those based on aluminum (aluminizing), chromium (chromizing), and silicon (siliconizing). Substrate
materials include nickel- and cobalt-base superalloys, steels (including carbon, alloy, and stainless steels), and refractory
metals and alloys.
This article is divided into two major Sections. The first Section describes the widespread use of diffusion coatings for
elevated-temperature protection of turbine components for aircraft engines or ground- or marine-based gas turbines. The
second Section reviews diffusion-coated ferrous alloys.
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