×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

High temperature bearing material recommendation/suggestions
2

High temperature bearing material recommendation/suggestions

High temperature bearing material recommendation/suggestions

(OP)
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.

RE: High temperature bearing material recommendation/suggestions

You don't ask for much!

I don't know of anti-seize compounds that would survive many cycles to that temperature. Actually there are not many metals that would survive prolonged exposure at that temperature.

The big question is, what is the environment; i.e., what is the potential for corrosion?

Ceramic maybe?

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

RE: High temperature bearing material recommendation/suggestions

The only thing that I know of that might work as a lube/anti-seize at that temp is HBN (hex boron nitride).
Do you expect your bolt to survive? What is it made of?
You are up in Ni alloy territory.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: High temperature bearing material recommendation/suggestions

(OP)
Yeah we’re in the Ni alloy territory. Items don’t need to last for typical plant life time, and welding of the nut after a cycle is a concern yes. There are other concerns I don’t need to elaborate into now, just looking for ideas on how you this specific topic.

Arent ceramic rings much harder than that, and very brittle?

Corrosion is less of a concern, it’s not in the process side but oxidation at the outer may be an issue yes.

Huub
- You never get what you expect, you only get what you inspect.

RE: High temperature bearing material recommendation/suggestions

Nitronic alloys have high resistance to galling.

RE: High temperature bearing material recommendation/suggestions

I don't think that Nitronic alloys would handle this temp.
Ceramics are brittle, but handle compressive loads well.
There are also grades that will not care about this temp.
And using two different ceramics is a good practice, such as Zirconia on SiC.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: High temperature bearing material recommendation/suggestions

May be machinable glass ceramic ? 800C to 1000C.
I could supply Technical Specification

RE: High temperature bearing material recommendation/suggestions

Graphite?

RE: High temperature bearing material recommendation/suggestions

(OP)
Thanks all for the input, I think I have sufficient leads to go from here.

Huub
- You never get what you expect, you only get what you inspect.

RE: High temperature bearing material recommendation/suggestions

For what it's worth... since I am familiar with cobalt alloys for turbine-engine hot section, mount self-aligning-bearings...

MIL-HDBK-62624 COBALT BASE ALLOY INVESTMENT CASTINGS

1.1 Scope. This handbook gives guidelines for chemical, mechanical and physical
properties for investment castings of the cobalt alloy commercially known as L-605, Haynes 25,
or Unitemp L605. This handbook is for guidance only. This handbook can not be cited as a
requirement. If it is, the contractor does not have to comply.

1.2 Purpose. The material covered by this handbook is primarily for parts requiring
strength at high temperatures up to 1500 degrees Fahrenheit (“F) (816 degrees Celsius (“C)) and
oxidation resistance up to 2000°F (1093°C).


I suspect this is 'a day-late and dollar short'

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

RE: High temperature bearing material recommendation/suggestions

(OP)
Thanks. In unfamiliar with that spec or material.

Can you maybe explain in more detail how that spec relates to my question? I understand from your post it’s for castings, whereas I’m looking for a simple flat ring.
Data I could pull of the interwebs for L605 is a hardness of about 25 HRC (https://www.hpalloy.com/Alloys/descriptions/HAYNES...), which seems to be far more than what my base material is (BHN 180), making it unsuitable.

Huub
- You never get what you expect, you only get what you inspect.

RE: High temperature bearing material recommendation/suggestions

Being a hard material it can be polished to decrease wear on the mating nut.

Is this the same joint as before and, if so, where is the washer? Between 1 and 8 or between 3 and 8? If 8 is turning, then that isn't good for the o-ring.

I'd suggest talking with Kennametal - some of these alloys look suitable (except for not wearing out) https://www.stellite.com/us/en/products/stellite-f...

However, they have others that may be more suitable.

RE: High temperature bearing material recommendation/suggestions

(OP)
Washer ring would be between 3 and 8. 3 is turning

Huub
- You never get what you expect, you only get what you inspect.

RE: High temperature bearing material recommendation/suggestions

How does hardness differential make it unsuitable? Typically in bearings a high hardness differential is preferred as it generally reduces the chances galling.

RE: High temperature bearing material recommendation/suggestions

(OP)
Hardness differential is indeed preferred/required. What I was hoping/looking for is a ring material that's softer than my base materials, such that it works as a sacrificial part that I can simply replace once worn. I dont want my expensive parts to wear out first. If, at this temperature, Im only left with harder (than my base) materials, than thats just it.

Huub
- You never get what you expect, you only get what you inspect.

RE: High temperature bearing material recommendation/suggestions

Keep in mind that hexagonal boron nitride is an effective high temperature solid lubricant.

RE: High temperature bearing material recommendation/suggestions

(OP)
Do you maybe have a link to a datasheet or other reference, as an example for HBN?

Huub
- You never get what you expect, you only get what you inspect.

RE: High temperature bearing material recommendation/suggestions

Suggest you google "boron nitride ceramic" for more information. Or just order a piece from McMaster - https://www.mcmaster.com/boron-nitride/

We used to machine chunks of this for weld and braze tooling at the rocket factory (it machines pretty nicely with plain hss tooling, just go slow), it has a wonderful property of not wetting to molten metal. Also used it as dielectric/insulation spacers some high temperature tungsten heaters for resistojets and arcjets. Oh, and used cans of the spray-on powder as high temperature anti-seize, along with water/alcohol/powder solutions to swab onto fasteners prior to assembly, same idea.

RE: High temperature bearing material recommendation/suggestions

(OP)
Thanks TBE. This HBN is relatively new for me so forgive me any dumb questions.
Is this applied as a powder just on the threads, or is the powder processed into some liquid to make it a lubricant, and then applied?

/edt: as per McMasterCarr’s info, I looked into Krytox XHT-BD. It seems, but again this may be me unknown with HBD, this lubricant is rated for 300-350 deg C. I assume that’s not an issue since I only require the lubricant for initial bolt-up, and not for any dynamic purpose?

Huub
- You never get what you expect, you only get what you inspect.

RE: High temperature bearing material recommendation/suggestions

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.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: High temperature bearing material recommendation/suggestions

(OP)
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.

RE: High temperature bearing material recommendation/suggestions

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.

RE: High temperature bearing material recommendation/suggestions

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 ...

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: High temperature bearing material recommendation/suggestions

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.

https://www.techbriefs.com/component/content/artic...

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close