Surface Coating for Copper Busbar

Hello Yasser, Not to sound smart, Gold plating is resistance to corrosion, good conductor of electric. Not too sure about durability if switch often if the contacts slide or open/close like a relay.

If manufacture is know they would be the best source for repair infomation.

Charles

As a replacement to gold which is very expensive, why not trying tin coating?

As well as gold, tin coating has high resistance to corrosion and oxidation. It's more economical comparing to gold.

Jacob,

I agree with you that Tin coating will serve the purpose.

Most of the helicopter bus bars are Tin plated to avoid surface degradation.

Yep............I agree.

In marine applications the preferred conductors are tin coated, copper wire.

Gold and platinum are used for contacts, particularly in safety equipment.....even down to some of the lowly thermal and smoke detectors.

Silver is very bad as a coating when there is anything that might contain sulfur in the atmosphere. The sulfur can / will combine with moisture to form H₂SO and that will make "whiskers" grow on the silver, which degrades and eventually causes failure of the electrical equipment. Tin plating is recommended.

Not sure if Chlorine will do something similar, but is sulfur a byproduct of your process?

Link

I have once designed and supplied high current cell-shorting switches to chemical plants. They had 1.5 mm think pure silver contact tips. Of course, this was a very old design, and contacts were in oil. Not affected by sulphur. Any platng anywhere else is immaterial, in my opinion. Th high mv drop across the switch implies eroded contact tips, you should look there for the source of the overheating.

Good day, silvering fluid (silver potassium / sodium cyanide) wiped over the cleaned busbars will probably give you the best results. Silvered busbars also 'corrode' but the difference being that the silver oxide is conductive and copper oxide, a very poor conductor. We have compared and used silvering fluid to great success in highly corrosive environments. kind regards, leon

The uncertainty about the original metal coating (silver vs nickel) makes it harder to judge. If I understand correctly, silver is a good choice in contact with chlorine, but I don't know about the alkali part. Usually silver is terrible if sulfur is present (fast source of tarnish), but it might be okay if submerged in oil. Gold is an excellent conductor and corrosion resistor, but it is relatively soft and might not withstand the repeated "wiping" action of heavy contacts. Nickel didn't seem to work well, and I don't know about tin.

Another approach might be to use a vacuum contactor, in which the contacts are sealed and thus not exposed to corrosive atmospheres.

All of this is rather conjectural. I have run across this in bits and pieces, so please take this as just exploratory ideas. Ask some switch suppliers. Good luck with this!

The best material we have found is silver plating. If the bus connection is exposed to damp conditions, there are plenty of loaded greases that will keep the joint dry and conductive. The best silver plating is electroplated. Brush plating can also br used. In a pinch, you can use a wipe-on plating like Cool-Amp. If you require a life-time connection, you can obtain some woven silver screen (~100 mesh) and cut a gasket (washer) out of this screen. When this screen washer is bolted between two silver plated bus bars and the bolts torqued, the screen will deform and create a joint that is impermeable to liquids and gas. We have 50 year old connections made trhat way that still have the same millivolt drop they had the day they were made and have 150,000 amps flowing through them on a continuous basis.