Metal Flakes Testing

[djm883]

I have a rotating forged steel shaft within a bronze sleeve bearing that has had poor maintenance and water intrusion for approximately 25 years. We have removed the bearing cap and found several of the shafts have flaking steel from the shaft. These flakes are magnetic.

There are three possibilities for the flakes:
1. The shaft being in such a corrosive state for so long has began to flake.
2. The grease thickner separated from the oil and has collected steel or bronze particles and gives the appearance like it is steel.
3. Installation drawings say to apply graphite to the shaft. Don't believe this is a possibility since the flakes are magnetic.

I have talked to a mechanical testing lab and will have the flakes tested for the microstructure and chemistry. Is there anything else we could test? Is there anything I can do on my own to check?

Thanks.

 

[CoryPad]

What equipment do you have? If you don't have metallurgical preparation equipment, an optical microscope that can magnify ~ 500 times, and a Scanning Electron Microscope with Energy Dispersive X-ray Spectrometer, there likely isn't much you can do.

 

[EdStainless]

Some labs do a lot of wear particle testing of lubricating oils. Look around and see if there is someone near by that specializes in this work.

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