piston metal

[Philip BurleyParticipant @philipburley44197]

[Philip BurleyParticipant @philipburley44197]

What is the best metal for a piston in bronze cylinder ? Will aluminium work ? cast iron ? bronze on bronze ?

regards Phil

[JasonBModerator @jasonb]

Steam, IC or other?

[Howard LewisParticipant @howardlewis46836]

If moisture in the form of steam (It will condense in a cold cylinder ) is present, I would be wary of using Aluminium in contact with any alloy containing copper. Any electrolytic action will corrode the Aluminium.

So my preference would be for a cast iron or steel piston, rather than running like for like materials.

You may need to use slightly tighter clearances to allow for the ferrous material having a lower coefficient of expansion than Aluminium (alloy ) to minimise leakage.

The rings should cope with most of the leakage, but the piston is part of the leak path.

HTH

Howard

[Thor 🇳🇴Participant @thor]

Hi Phil,

I have been using pistons made from free-cutting stainless steel (303) in gunmetal cylinders in several of my steam engines and that has worked well so far. Gunmetal may not be quite the same as bronze, bronze would probably be a bit harder.

Thor

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