medic362

Topic: Possible sources of Chloride cantamination in hard chrome bath?

Any ideas on what would cause a sudden spike in chloride levels in a plating bath (above 10000 ppm in reverse etch and above 5000 ppm in plating bath)? At a total loss as to where this might have come from. What could cause this kind of level?

DustinGebhardt

Re: Possible sources of Chloride cantamination in hard chrome bath?

Do you have any sources of chloride in the pretreatment or pre-chrome baths? I would check each and every bath, going down the line from the chrome bath and seeing if this leads anywhere. Also check your incoming water supply.  

-Dustin Gebhardt, CEF

Advanced Manufacturing/Finishing Engineer

Moen

Sanford, NC

medic362

Re: Possible sources of Chloride cantamination in hard chrome bath?

There are no other baths before this reverse etch bath. I am told that our city water checks low (same range as it always has) and we have not changed any process chemicals. Wondered if there was any "smoking gun" chemical or substance that would caude this problem to arise this suddenly (3 month period from virtually zero to off the charts). What is more perplexing is that a good percentage of our product does not even go into this reverse etch bath which makes me wonder if the contamination of the actual plating bath is drag out from the reverse etch bath as we originally thought or if it could be some other substance that was introduced into both baths?

jimtrottier

Re: Possible sources of Chloride cantamination in hard chrome bath?

I don't know this is a quandry. Did you do a tank clean out and a leach with hydrochloric acid and possibility not remove all of the leach before going back into production? Have you added a hydrochloric rinse before the chrome? I don't know but you do have a problem. Also are there any new people that make adds since this started?

Jim

Last edited by jimtrottier (04/13/2010 - 03:44 AM)

medic362

Re: Possible sources of Chloride cantamination in hard chrome bath?

We did none of the above. In my figuring, IF hydrochloric acid showed up as a 1:1 ratio of chloride (if that makes any sense) there would have had to be about 2.5 gallons of acid per tank introduced. I admit, I don't know the specifics of how something like hydrochloric acid shows as chloride, but this seems like something that would have been an obvious error in an addition.

Is this thinking correct or would a much smaller amount of something like hydrochloric acid result in the extremely high chloride levels? How much acid would have had to be added to a 500 gallon tank to produce 5100 ppm chloride? I appreciate all of your comments.

As an aside, we did add an improper amount of barium carbonate to our plating bath due to an improper tank volume in the calculation. This addition dropped our sulfate level to near zero (.02 oz./gal.). We did not see any ill effects in our finished product due to the chloride taking the place of the sulfate as a catalyst as I understand it. Since this addition was only done to the plating tank and not to the reverse etch tank, I had eliminated this as a possible source, as the chloride problem seems to originate in the reverse etch tank. Figured I would throw it all out there, as my experience is very limited in this department.

Thanks again for any and all comments.

beav

Re: Possible sources of Chloride cantamination in hard chrome bath?

How are you measuring the chloride?

medic362

Re: Possible sources of Chloride cantamination in hard chrome bath?

We have sent samples to 2 different labs for analysis. I cannot give anymore details related to testing because frankly, I don't know how they do it. Our initial sample was sent to the same lab that we always use. Both labs returned elevated chloride levels.