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Ted Mooney, P.E. RET
Pine Beach, NJ
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for Metal Finishing since 1989
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Effect of potassium formate on Zn-Ni plating
Q. Sir,
We are an aerospace company which manufactures hydraulic pumps that are used in the air planes. Some of the pump components are made of low alloy steels like 4130, 4140, and are cadmium plated. These components are subjected to de-icing chemicals used in Europe. These chemicals as I understand it, are glycol based and I am given the names like potassium formate or potassium acetate. Because of these chemicals coming in contact with cadmium plated parts, parts show corrosion on cadmium plated surfaces.
We are recommending to plate parts with zinc-nickel, which is expected to perform better than cadmium plating. However, we do not have sufficient data to substantiate that. Our customer, a major aircraft company, is questioning if zinc-nickel would survive de-icing agents used in Europe. I would appreciate any light you can shed on the subject.
Thank You,
- Kalamazoo, Michigan, USA
2002
A. Sir,
I am pretty sure that de-icing chemicals for airplanes will not attack aluminum. If you want a good corrosion resistant coating for your low alloy steel (4130, 4140) you could chose aluminum as a protection. AlumiPlate, Inc. electroplates parts with pure aluminum. For your purpose a 0.3 mils thick coating should do it.
- Minneapolis, Minnesota, USA
2002
? The potassium based deicers you are referring to are not glycol based, and are primarily used for runway deicing. Is your problem related to "salts" in general or the glycol products that are used for aircraft wing deicing, or is it the potassium based products? You better have your parts tested to determine exactly which products are causing the problem.
Joe Musil- Philadelphia, Pennsylvania, USA
2002
A. Potassium formate which is used as a deicer reacts with zinc and contact between zinc and the coating should be avoided.
Ronan Kelehan- Dublin, Ireland
Q. Does anyone have experience with the corrosion resistance of nickel plated copper wire such as used in EMI shielding when exposed to potassium formate solutions?
Tom Burke- Newburyport, Massachusetts USA
December 13, 2018
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