Need a conductive material bonded to stainless steel cylinder

A. Hi Charlton.
There are about 20 plateable metals, and they are all conductive (although not necessarily truly suitable as electrical contacts). They can all be electroplated onto stainless steel after an initial Wood's Nickel Strike. You can search the site for Wood's Nickel Strike and you'll see how to formulate it, but in brief the problem with plating onto stainless steel is that it instantly forms an oxide skin, and you need the Strike to simultaneously dissolve the oxide in acid while applying a thin layer of nickel

Nickel plating is relatively conductive and is generally suitable for electrical contacts (you see it on 'chargers' for all sorts of electronic devices) and it's reasonably inexpensive. But nickel would not be adequate for low voltage / low current digital signals, for that you would need gold plating (as you see on video game cartridges, smart phone accessories, and circuit board edge connectors).

'Conductivity' in this application is a bit nebulous and there are so many coating choices that it's hard to go further while the requirement is so vague. Please tell us what you are trying to build and why, and readers will surely be able to offer far more detailed advice.

Luck & Regards,

A. The last time I looked, stainless steel is already electrically conductive.