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HARD CHROME DISSOLVED

Will hard chrome(.0002") be dissolved from tool steel in a ultrasonic tank with alkaline cleaner(pH13) at 165F degrees?

Darrell Elkins
- Elgin, Illinois, USA
2002

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Do you mean to ask whether this would be an effective stripping method, or do you mean to ask whether there is danger in exposing chrome to this condition?

The answer to the first is, no, this would probably not be a dependable stripping method; the answer to the second is, yes, chromium is amphoteric and high pH probably will damage it.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2002

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Ted,

My interest was the later, will a high pH alkaline cleaner @165F with ultrasonic be harmful to hard chrome(.0002/.0003 thickness)?

Thanks,

Darrell Elkins
- Elgin, Illinois, USA
2002

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The temperature per se is certainly no problem, and neither is the ultrasonic transducer. But I would expect a hot pH 13 alkaline clean to damage (partially dissolve) hard chrome plating. At the least you would want to test some scrap pieces and prove me wrong.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2002

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Ted,

I will set an evaluation soon, as I will be traveling to our manufacturing plant next week. If I understand correctly, the hard chrome is not a perfect seal and has some micro cracks. The alkline cleaner is made up of 30% Sodium Hydroxide and 8% Potassium Hydroxide then it is diluted to a 25% concentration.

Thanks again for your insights.

Darrell Elkins
- Elgin, Illinois, USA
2002

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I don't believe the porosity and cracking of the chrome is a problem because this caustic solution should not attack the tool-steel substrate. Rather, the problem would be the chrome itself dissolving into the caustic.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2002

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Ted,

It does seem as though the A2 steel is pitted where the chrome has come off. We are going to evaluate Ethylene glyco n-butyl ether(110F) as a cleaner replacing the Sodium and Potassium hydroxides.

Thanks,

Darrell Elkins
- Elgin, Illinois, USA
2002