Chromium coatings microporous

A potential problem that could result from this system of corrosion control would be the undermining of the chromium and the possibility that the brittle chromium deposits could flake off the surface. This potential problem was prevented by the development of a microcracked or microporous chromium coating. These coatings contain microcracks or micropores that do not detfact from the bright appearance of the chromium. They are formed very uniformly over the... 

Microporous chromium coatings are produced by first electroplating a bright nickel layer containing suspended nonconductive fine particles. Over this a chromium layer is deposited which results in a mirror finish. As the chromium thickness increases the number of pores decrease. For a chromium deposit of... 

Similar results may be obtained by another technique in which, before application of the chromium, a thin layer of nickel containing small inert particles is deposited on top of the bright nickel. The inert particles equate in the chromium to a very large number of tiny pores—hence, this type of coating has become known as microporous chromium . 

Through a chemical treatment of iron-chromium based alloys, supported catalysts can be prepared in one main step from the substrate which furnishes constitutive elements of the coating. The conversion coating is a microporous physically and chemically heterogenous medium with a fractal structure. Variations of the compositional and textural properties are studied against nature of the substrate, duration of the chemical treatment and conditions of thermal or chemical post-oxidation treatment. 

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