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Electroless Nickel
I have some electrical circuit breakers in a wastewater treatment plant and they get corroded due to the existence of hydrogen sulfide. Any idea if I can use EN (electroless Nickel) plating process to plate the DC contacts of the breaker that are made of copper with out affecting the contact resistance too much. FYI the applied voltage on the DC contacts are 48 Volts.
Taha Moahmmed- Phoenix, AZ, USA
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Contacts are often electroless nickel plated, including almost all of the contacts on battery chargers of every description. After you have sample parts run, you could measure the resistance to be sure . . . but to me it sounds like a perfect application.
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 Ted Mooney, P.E. finishing.com Brick, New Jersey |
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The major limitation with the use of nickel coating for connector contacts is its tendency to form a hard and insulating oxide film. Since the prime requirement of a coating for use in connector contacts is to maintain a low contact resistance, nickel is not considered as a suitable choice in many instances. However, nickel plating has long been used as a popular and cost-effective choice for battery contact material in applications such as flashlights, toys, etc. where the current load is sufficient enough to break the oxide film on the nickel coating.
Chudnovsky [1] has reported that electroless (EL) nickel plating withstands the corrosive, hot and humid atmosphere much better than traditional silver and tin plating, which have been nearly destroyed in H2S environment. According to her, it is an effective alternative to silver and tin plating for protecting circuit breaking equipment from corrosion up to one year without significant discoloration in corrosive atmosphere. Dervos et al. [2] have recommended that EL Ni-P coating could be used as a low-cost stationary contact material and it can perform well even under adverse working conditions. EL Ni-B coating is considered as a useful alternative for gold and silver in microelectronic devices. EL Ni-B coating possess good solderability compared to EL Ni-P coating because its oxide layer is thin and can easily be penetrated by the solder. Dervos et al. [3] have recommended EL Ni-B coating as a possible solution for low-cost stationary contact material.
1.B.H. Chudnovsky, Proc. 49th IEEE Holm Conference on Electrical Contacts, IEEE, 2003, p. 98.
2.C.T. Dervos, P. Vassiliou, J. Novacovich, C. Kollia, IEEE Trans. Comp. Packag. Technol. 27(1) (2004) 131.
3.C.T. Dervos, J. Novakovic, P. Vassiliou, Proc. 50th IEEE Holm Conference on Electrical Contacts and the 22nd International Conference on Electrical Contacts, IEEE, 2004, p. 281.
T.S.N. Sankara Narayanan
- Chennai, Tamilnadu, India