Brown Sugar

[MolaKule]

1.) What is "Brown Sugar" AND 2.) what type of liquid, used in specialized 'severe boundary condition' greases, would cause Brown Sugar to form?




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[MolaKule]

Guidelines for the Question of the Day:
4. Please, no off topic posts.

 

[spk2000]

1)Crystals from the cane syrup

2)Molasses

 

[hotwheels]

Originally Posted By: MolaKule
1.) What is "Brown Sugar" AND 2.) what type of liquid, used in specialized 'severe boundary condition' greases, would cause Brown Sugar to form?




Guidelines for the Question of the Day:

1. No Piston Cup Lapel Pin will be awarded to the same person within 14 days of a previous award.

2. Please respond with a complete sentence or explanation.

3. Please do not post links. If a question arises as to the need for clarification, then sources and links may be requested.

4. Please, no off topic posts.



Would "brown sugar" be molybdenum oxide forming and falling out of suspension under very high pressure?

hotwheels

 

[OneEyeJack]

Brownish particulates are a telltale sign that a PFPE lubricant is breaking down as a result of the catalytic chemical reaction.

Is this the "brown sugar" to which you refer?


PFPE

 

[Kira]

ANSWERS:
1) "Brown Sugar" is a Rolling Stones song from 1971.
2) PTFE teflon additive. Kira

 

[MolaKule]

Thanks to all who responded with serious technical answers and who really want to learn about Tribology.

Questions 1 and 2 were related to PFPE liquids and PFPE grease formulations. These PFPE liquids are produced primarily by DuPont under the Krytox brand.

Sometimes familiar household descriptive phrases are applied to tribological observations.

PFPE's are part of a class of costly, yet high performance synthetic fluids called, "perfluorocarbons."

The type of perfluourocarbons being discussed here are perfluorinated polyethers or PFPE's.

Greases made from PFPE are used in extremely high load, wide temperature applications such as airplane bearings, space bearings, and "sealed-for-life" bearings.

These greases are formulated with sodium nitrates (as anti-wear/anti-corrosion agent), PTFE (Teflon) powders (thickening agent), moly disulfide powder as an extreme pressure (EP agent), and other additive agents.

These greases can often run under extreme loads at extreme temperatures for more than 25,000 hours without degradation.

Under severe boundary conditions and extremely high temperatures in bearings, this grease can exhibit "tribocorrosion."

Tribocorrosion with PFPE's can be observed as a crystalline, brownish appearance called, "Brown Sugar."

Brown Sugar caused by high pressures breaking apart the fluorine atom apart from the carbon atom in the PFPE molecule, to form iron fluoride at the surface.

OneEyeJack is now the proud possessor of the new 3D Piston Cup Lapel Pin for submitting the nearest correct response.

 

[MolaKule]

The second to last sentence should read:

Quote:
Brown Sugar is caused by high pressure breaking the fluorine atom from the carbon atom in the PFPE molecule, to form iron fluoride at the surface.