non-metal parts for Steam?

[Anatol]

I'm thinking about non-ferrous, but also new composites as solutions to steam engine challenges - I'm looking for a 'magic' material, non-corroding, minimal thermal expansion, precision machinable, 'self lubricating', able to make seals at high pressure, high temp with water humidity.
Is that too much to ask
For things like piston valves...
Does anyone have experiences with any of the exotic new plastics?
Teflon has interesting qualities, but it creeps.
Graphite-filled vespel seems to have possibilities.
I saw someone used delrin in a steam engine.
Torlon, Ryton ...,molybdenum filled nylon?
glad to know anyone's experience
thanks

 

[kadora]

Good question Anatol .
I am interested in using plastic parts in engines too.
Here in Slovakia is possible to buy POM material /probably DELRIN/
in many modifications /POM C,POM H,POM CTF,POM CGF/
but this POM material can withstand hot water + 80 Celsius only
short time + 120 Celsius.
POM is quite cheap so I use it for producing casting patterns
due to its excellent machinability .

 

[vederstein]

Have you looked at Kynar?

 

[Anatol]

Have you looked at Kynar?

I have now, thanks
it looks like a coating as opposed to a machinable plastic, which is what I was thinking about.
I've heard there are some pretty extraordinary teflon sprays out there.

 

[lohring]

Look at ceramics. As an example, some zirconium "alloys" are extensively used in dentistry. See zirconium dioxide and yttria stabilized zirconium. They act like metals for crack resistance; are strong and temperature resistant; and are easily machinable in their sintered state. They shrink on firing but that can be compensated for in the design.

Lohring Miller

 

[Anatol]

Look at ceramics. As an example, some zirconium "alloys" are extensively used in dentistry. See zirconium dioxide and yttria stabilized zirconium. They act like metals for crack resistance; are strong and temperature resistant; and are easily machinable in their sintered state. They shrink on firing but that can be compensated for in the design.

Lohring Miller

thanks
I took a look at discussions on machining them. EDM ultrasonic, diamond, laser -all bit out of my league

 

[lohring]

They are milled in the as sintered state with standard carbide tools. Diamond can be used in the fired state. Cerec makes one type of milling unit. Here is a video of the two head mill in action.

Lohring Miller

 

[Anatol]

They are milled in the as sintered state with standard carbide tools. Diamond can be used in the fired state. Cerec makes one type of milling unit. Here is a video of the two head mill in action.

Lohring Miller

Dramatic! High Tech! outta my league
thanks for the vid though

 

[WOB]

How about Macor machinable glass ceramic? http://ceramicproductsinc.com/macor.html

WOB

 

[Anatol]

How about Macor machinable glass ceramic? http://ceramicproductsinc.com/macor.html

WOB

thanks, I took a good look - machinable glass, that's exotic
but workable with regular tools. looks interesting.

 

[GlennS]

I have now, thanks
it looks like a coating as opposed to a machinable plastic, which is what I was thinking about.
I've heard there are some pretty extraordinary teflon sprays out there.

I believe Kynar 500 is the coating.

Search "kynar bar stock" and you'll find some stock to machine. What I saw was listed as "PVDF Kynar".

 

[Anatol]

How about Macor machinable glass ceramic? http://ceramicproductsinc.com/macor.html

WOB

I've been looking into this more. it seems very interesting - machinable with regular tools, no post machining sintering needed. It seems you can polish it very smooth. I wonder if it would make a good piston? Its certainly not 'self-lubricating' which would be a useful quality.