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Electroplating without acid pickling
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Q. I want to do zinc electroplating process without acid pickling.
Is it possible?
Please guide which chemical can be used to avoid acid pickling.
Quality Assurance Engineer - Nashik
A. Hi Rajendra. The problem here is that, although you may not agree, your question is quite vague so any answer offered may mislead you. The problems are ...
• The word "pickling" introduces semantics issues. Indeed almost all plating involves an acid activation step, a fairly quick dip, which some call "pickling", but which is a far cry from the scale breaking, strong acids, and extended treatment times called "pickling" in a steel mill.
• Perhaps half of all zinc electroplating is done in 'acid zinc', although cyanide zinc and alkaline non-cyanide are alternatives. So, specifying 'no acid pickle' doesn't eliminate exposure to acid unless you're very clear about it.
• It may be possible to blast the components immediately before plating and go directly into the zinc electroplating tank but this will be highly dependent upon what kind of parts they are and what kind of production process you envision. One bolt can be blasted and immediately plated, but clearly you can't blast one bolt at a time then load 1000 into a plating barrel and barrel plate them.
• When you want to avoid pickling but we don't know why, we can't help wondering if you're trying to avoid hydrogen embrittlement, and whether you realize that the plating process will cause it anyway.
Please explain what kind of component you want to plate, why you don't want to expose it to an acid pickling process, and what the general production plating process looks like (one large sheet manually plated, automatic barrel plating line with hundreds of parts per barrel, etc.) Thanks!
Luck & Regards,
Ted Mooney, P.E. RET
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finishing.com - Pine Beach, New Jersey