Hello guys, I'm fabricating a simple dock charger for a robot. The robot has two cylindrical copper terminals which gets aligned to a spring loaded copper latch on the dock. A current of around 10 Amps flows through the contact (no arcing, since power is switched on after they are in contact). My vendor gave me an 'Electrical grade' copper tubing and a sheet, but they have turned blackish/dull in few weeks. I haven't tested the difference in conductivity, but I wanted something that would not corrode in open environment (rain, sun, dust and 50 degree ambient temperature). Since this is going to be in production, I would like a material to be easily available. Any other materials you guys suggest? Any special grade of copper? Thanks in advance