These changes will also affect cathode efficiency. This mixed catalyst has the advantages of improving cathode efficiency, covering power and ability to plate on bright nickel layers when compared to the straight sulfate catalyst type.Īny change in current density will generally involve a corresponding adjustment in temperature to keep the solution within the optimum plating range. ![]() The most common electrolytes employed today are based on the dual sulfate/fluoride catalyst. Simple preparation Tolerant to contamination TABLE I - Decorative Hex Chrome Electrolyte Systems Type The primary differences among the systems are outlined in Table I. Decorative Hexavalent Electrolytesįour types of hexavalent chromium electrolytes are commonly employed: Typically, articles plated to service condition 1/2 would use regular chromium plate, whereas plating to service condition 3 or above would use a discontinuous layer (ASTM B456). Inducing micro-discontinuities (microcracks) across the surface spreads the corrosion current and slows the corrosion rate. Deep pits form at these points and rapidly penetrate through the nickel deposit and the component substrate. Because these cracks or pores are relatively widely spaced, the current developed by the chromium/nickel couple is concentrated at a few points. Corrosion is an electrochemical mechanism. ![]() Failure of bright chromium plate is often due to deep pits developing as a result of corrosion starting at random cracks or pores in the chromium surface. The selection of a continuous or discontinuous layer depends on the level of corrosion resistance required. Discontinuous deposits are formed by depositing the chromium on microporous (or microcracked) nickel plate. Registration Opens for Electroless Nickel Conference 2022īright chromium can be applied as continuous (regular) or discontinuous layers.
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