The NF A91-473-2021 standard specifies the test method for chromate reaction films on the surface of zinc, cadmium, aluminum-zinc alloys and zinc-aluminum alloys in metals and Miscellaneous Inorganic Coatings. The standard describes in detail the formation of chromate reaction films and the evaluation method for the protection of metal surfaces, including the thickness of the film, adhesion, corrosion resistance, weathering resistance and other performance tests. Through these tests, the mass and protective effect of coatings can be effectively evaluated to ensure their Reliability under different environment conditions. This standard helps to promote the standardization of chromate treatment technology to ensure the durability and protective effect of metal surface preparation products in various industrial applications.