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High temperature bearing material recommendation/suggestions 2

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XL83NL

Mechanical
Mar 3, 2011
3,054
As a follow-up to this post, I'm looking for material recommendations for a simple ring I intend to use between a nut and fixed component, where the nut, due to threads, will exert a force on the fixed component once the nut is tightened. Purpose of the ring is to act as a sort of sacrificial ring, that will prevent any wear on the twisting nut or underlying fixed component. Ideally, rings should be easy replaceable and cheap.

Nut and fixed component are of the same material, have a hardness ~ 180 BHN, and will see temperatures up to max ~ 950°C. The material I'm looking for should hence be soft, be able to withstand some bearing stress at temperature (albeit low), and can withstand high temperatures. The lubricating action of the ring's material is probably out of the question, and can be accomodated by other means (e.g. anti-seize).

Bearing bronze alloys (like RG7 or phosphor-bronze CuSn8) are ideal materials for bearing applications, but wont handle these temperatures.

Any thoughts?

Huub
- You never get what you expect, you only get what you inspect.
 
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You can get it as an aerosol spray or a powder.
We used to get powder and mix in alcohol and paint surfaces with it.
I don't recall what alcohol we used, most likely either isopropanol or methanol.
In either case it was pure.

This following includes a serious warning.
This can cause fire, explosion, and serious injury.
If you microwave the alcohol/HBN mixture the HBN will stay in suspension better.
This has to do with trace amounts of water in the solution.
But please be careful if you choose to do this.
We used to take a microwave oven out into the parking lot when we did it.

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P.E. Metallurgy, consulting work welcomed
 
Lol Ed. Thanks for the info. I’m quite sure that under our QHSE requirements we won’t even consider a microwave!🤭

Huub
- You never get what you expect, you only get what you inspect.
 
Ed, can you elaborate? I cannot imagine a microwave doing anything other than warming a slurry of HBN and alcohol, perhaps to dry it. With alcohol present the temperature cannot rise above the boiling point.
 
I don't know the mechanism. All I know is that the slurry got thicker and was easier to work with.
We only started one small fire ...

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P.E. Metallurgy, consulting work welcomed
 
It appears that the mechanism is exfoliation of the HBN. This is done for many materials with a planar crystal structure such as graphite and bentonite clays. That is a very interesting tip. Microwaves are perfect for such a process as they can heat the HBN from inside the crystal.

 
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