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The electroplating process consists of two main steps: (i) the mass transport of chromium ions through the electrolyte to the surface of the electrode, and (ii) the reduction of chromium ions at the cathode through chemical reactions. c The fundamental equations needed to model the system are: 2.1 Conservation Balances n
This chapter contains sections titled: Principles. Theory of Chromium Electrodeposition. Hexavalent Chromium. Methods of Operations of Chromium Plating Solutions. Mixed Catalysts and Selfregulating Baths. Chromic Acid Baths: Operating Conditions. Throwing Power.
Figure 12.20-1 presents a process flow diagram for hard chromium electroplating. The process consists of pretreatment, alkaline cleaning, acid dipping, chromic acid anodizing, and chromium electroplating. The pretreatment step may include polishing, grinding, and degreasing. Degreasing
21 Φεβ 2011 · In decorative applications, the chrome is plated as a thin (0.25–0.8 μm) layer over nickel to provide an economical and highly corrosion resistant deposit. Most decorative chromium deposits are produced using hexavalent chromium electrolytes.
Chromium plating is traditionally made from a solution of chromic acid (CrO3 which forms H 2 CrO 4 after dissolving in water) and sulfuric acid (H 2 SO 4) using insoluble anodes. The chromium is reduced to metal from the hexavalent state due to the catalytic effect of sulfate ions.
Hexavalent chromium (Cr6+) conversion coating (CCC) serves as a corrosion inhibitor in metals, such as zinc and its alloys, magnesium and its alloys, aluminium and cadmium.
The electroplating process, however, has significant health and environmental impacts. Air emissions during the electroplating process contain hexavalent chromium (Cr+6) - a known...
