Is plating a “homogeneous material”?
According to the EU Commission, plating and coatings are “homogeneous materials” as they differ in composition from the substrate material. Keep in mind that in chemical analysis, platings and coatings are commonly removed from substrates by chemical means, and are not “mechanically disjointed” from the substrate. This is not such a big problem technically, however, since there are quite a few chemical methods for removing plating and coatings from surfaces. One exception to the chemical removal of coatings from substrates is hexavalent chromium conversion coatings. Since hex chrome coatings vary in mass over time due to exposure to the environment and because hexavalent chromium coatings are often very thin (on the order of 200 nanometers), determining the total coating mass on a chromated surface is difficult, if not impossible. Besides, there exist no certified reference materials with which such a method could be evaluated, and it is unlikely that such reference materials will ever
According to the EU Commission, plating and coatings are “homogeneous materials” as they differ in composition from the substrate material. Keep in mind that in chemical analysis, platings and coatings are commonly removed from substrates by chemical means, and are not “mechanically disjointed” from the substrate. This is not such a big problem technically, however, since there are quite a few chemical methods for removing plating and coatings from surfaces. One exception to the chemical removal of coatings from substrates is hexavalent chromium conversion coatings. Since hex chrome coatings vary in mass over time due to exposure to the environment and because hexavalent chromium coatings are often very thin (on the order of 200 nanometers), determining the total coating mass on a chromated surface is difficult, if not impossible.
