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"Fluoborate Cadmium bath control"


As described in previous questions, I am working on a chipping and peeling problem on high strength steel fasteners that are required to be plated per NAS 672 [affil. link to spec at Techstreet] (fluoborate cadmium). In my work on this problem a question has come up in my own mind. We have been adding ammonium fluoborate as the nitrogen level in the bath drops. Apparently the ammonium ions are decomposing as plating proceeds. I would like to know the chemistry behind this. The next question that came to mind is, "Does the fluoborate ion decompose similarly?" If it does not, then are we building up the concentration of fluoborate ion in the bath by adding ammonium fluoborate? If this were the case, I would guess that the cadmium concentration in the bath should increase commensurately.

I guess the questions that I really need answered are:

1. Does the ammonium ion decompose during plating and if so, how?

2. Does the fluoborate ion decompose during plating too?

I appreciate any information that I can garner. I can not find much information on this plating process in the reference material.

Pat Reid
Consulting - Costa Mesa, California


Fluoborate Cad Plating Thickness Distribution. We are currently barrel plating cadmium on long slender bolts in a fluoborate bath per NAS 672 [affil. link to spec at Techstreet] as required by our customer. We are having a problem with plating thickness variation along the length of the bolt. When we have .0005" of plating thickness on the bolt head the thickness is around .0002"at the center of the shank. Is there any type of Leveling additive that can be used with this tank chemistry? We have slowed the barrel rotation down from about 14 rpm to about 6 rpm for another problem and it seems to have made this uneveness somewhat worse. I am looking at speed controls for the barrel motors. The faster rotation should give me the same effect as increased bath agitation. Would it be helpful to increase the bath agitation as well?

Will some of the solutions espoused in letter 35635 work in this situation - for instance greater cathode to anode distance, lower current density, increased bath agitation, etc. Will any of the levelers mentioned in this letter work in the cadmium fluoborate bath ( butyne diol, coumarin)?

Pat Reid
Consulting - Costa Mesa, California

November 1, 2011

Q. I would like to ask about Fluoborate cadmium plating. do I need to add auxiliaries, additives to increase the throwing power.

MRagheb Moris
plating shop employee - Montreal, Qc, Canada

November 2, 2011

A. Think about this for a minute. How can any one answer the question without knowing what you are using. So, What is your tank makeup, temp and ASF.

James Watts
- Navarre, Florida

November 6, 2011

A. Thank you James for your help. The tank make up is as per NAS 672 , 11-13 oz/gal Ammonium fluoborate and & 35-38 oz/gal cadmium fluoborate. pH 3.2-4, ambient temp., Current density 50 ASF. I really appreciate your help.

MRagheb Moris
Plating shop - Montreal, Qc, Canada

May 18, 2012

RFQ: I am starting to work with cadmium fluoborate process, and I am working on my hull cells to brighten the cadmium with licorice without any luck. My cadmium fluoborate is at 34 oz/gal Ammonium fluoborate is 11 oz/gal and boric acid at 6g/l, and I have tried licorice at 0.2g/l. All I get is white opaque panels. Are there any companies in north America that have a proprietary system for this bath?

Manoj Patel
- Montreal, Canada

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