Applications of metallurgical coatings

What do we mean by a “metallurgical coating?” A coating may be defined as a near‐surface region having properties differing from the bulk of the material, and coatings may be desirable or even necessary for a variety of reasons including economics, unique properties or the engineering and design flexibility that can be obtained by separating the surface properties from the structural requirements. Metallurgy, of course, is the art and science of procuring, shaping, treating and use of metals; but when we study metallurgical coatings we are concerned not only with the physical and mechanical properties of the materials themselves but also with the interaction of materials with their environments and the substrates. Thus “metallurgical coatings” involves us with a broad spectrum of problems ranging from deformation properties, to chemical interactions, to solid‐state properties.