Summary for electroplating without acid pickling Discussion
Electroplating without acid pickling is possible in some cases, but the thread shows that the question is too vague to give a single chemical substitute. The answerer warns that “pickling” can mean either a brief acid activation dip used in plating or the much harsher scale-removal treatment used in steel mills, so the term needs clarification. He notes that zinc plating can be done in acid zinc, cyanide zinc, or alkaline non-cyanide systems, so avoiding one acid step does not necessarily eliminate all acid exposure. He also says parts may sometimes be blasted immediately before plating and then plated directly, but that depends heavily on the part shape and production method. The answerer further cautions that if the goal is to avoid hydrogen embrittlement, plating itself can still cause it. He asks for details on the component, the reason for avoiding pickling, and the production setup before recommending a process.
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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.
Rajendra Shirsat
Quality Assurance Engineer – Nashik
September 14, 2021
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
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
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September 2021