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Ask the Expert Question-and-Answer Archive
(Hard Chrome Plating)by Randy Taylor, Advanced Tooling Corporation
November, 2007Hard Chrome on Aluminum
Q. What is the proper process to hard chrome aluminum and does it make a difference on the type of aluminum? Is it less expensive to spot chrome aluminum?
A. here are answers to parts 1 & 2 of your question;
What is the proper process to hard chrome on aluminum? The most common is clean, de-oxidize, then zinc or tin immersion followed by bronze or copper strikes, then go directly into chrome bath hot at 250 A/m2 (75 asf) then lower after several minutes. Plating hard chrome on aluminum is most challenging especially when conforming anodes or masking is involved.
Does the type of aluminum matter in electroplating? Yes. Aluminum alloys may contain a variety of elements such as magnesium, manganese, copper and silicon. Depending on the metal alloy, a variation in pre-treatment acids and acid concentrations may be necessary to remove undesirable microconstituents. Some platers favor a “double immersion coating process” to produce the most receptive film for satisfactory plating.
For more information on “pre-treatments for aluminum” contact coating specialist Mark Schario at info@platingprocess.com or marks@platingprocess.com
RT
