Coatings applicable to a variety of substrate articles, structures, materials, and equipment are described. In various applications, the substrate includes metal surface susceptible to formation of oxide, nitride, fluoride, or chloride of such metal thereon, wherein the metal surface is configured to be contacted in use with gas, solid, or liquid that is reactive therewith to form a reaction product that deleterious to the substrate article, structure material, or equipment. The metal surface is coated with a protective coating preventing reaction of the coated surface with the reactive gas, and/or otherwise improving the electrical, chemical, thermal, or structural properties of the substrate article or equipment. Various methods of coating the metal surface are described, and for selecting the coating material that is utilized.