Patent ID: 9057133
Filing Date: 2015-06-16
Classification: C23C

Abstract:
1. A processing solution for forming a hexavalent chromium free, black conversion film on a zinc or zinc alloy plating layer(s), the processing solution consisting of: nitrate ions and trivalent chromium in a mole ratio (NO optionally one or more metal ions selected from the group consisting of silicon, iron, titanium, zirconium, tungsten, vanadium, molybdenum, strontium, niobium, tantalum, manganese, calcium, barium, magnesium and aluminum; optionally phosphate ions and one or more ions selected from the group consisting of a sulfate ion, a halogen ion, and a boron ion; and the balance water, wherein the trivalent chromium is present in the form of a water-soluble complex with a chelating agent, wherein the trivalent chromium concentration ranges from 0.5 to 10 g/L; a molar ratio of the chelating agent to the trivalent chromium ranges from 0.2/1 to 4/1; and a pH of from 0.5 to 4.