Solid "dry" film lubricants?

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I dunno what made me realize there is no specific forum for solid/dry lubricants. A Moderator suggested back to me that the Grease Forum could be entitled to include these substances. It kinda makes sense because many greases are solids anyway at usefull temps and even the applications seem similar, like either grease or dry lube can be used.

http://en.wikipedia.org/wiki/Solid_lubricants

There are plenty of them to choose from and many of the EP componets, like Moly and Li, seem to overlap with solids anyway. PTFE, Graphite etc all fall under this category plus many more than I am aware.


I'll try reporting my own post to the Mods and we'll see if they do anything about the forum title. It's not it's the first time I suggested a forum tweek.
 
"Dry lubricants or solid lubricants are materials which despite being in the solid phase, are able to reduce friction between two surfaces sliding against each other without the need for a liquid media. Such lubricants, including materials such as graphite, hexagonal boron nitride, molybdenum disulfide and tungsten disulfide are also able to offer lubrication at temperatures higher than liquid and oil-based lubricants are able to operate. Such materials can operate up to 350°C in oxidising environments and even higher in reducing / non-oxidising environments (molybdenum disulfide up to 1100°C). Their lubricating properties are attributed to a layered structure on the molecular level with weak bonding between layers. Such layers are able to slide relative to each other with minimal applied force, thus giving them their low friction properties.

Limited interest has been shown in low friction properties of compacted oxide glaze layers formed at several hundred degrees Celsius in metallic sliding systems, however, practical use is still many years away due to their physically unstable nature."
 
I suppose it would depend on what type of lube you are talking about. Though most solid lubes are used in greases, since as you say, grease is sorta' a solid already.

Most of the information that you have posted has already been covered by Molakule in some of his very informative posts.

If you want to talk about these things that's cool, but it would help to know in regard to what.
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What purpose would a solid/dry lubricant forum serve, other than an academic discussion of their characteristics?

I know powdered graphite can be purchased. Beyond that, can someone buy and use moly, PTFE, ceramic, etc.. in their raw state?

Grease is a thickener that carries liquid and solid components. It is not a solid lubricant.

Maybe a forum on lubricant components for those that want to discuss what lubricants are made of (liquid and solid) is more appropriate, if there is an interest in this....maybe tribologist?
 
Normally "solid film lubricant" doesn't refer to a grease additive.

It is more likely to be a solid lubricant in a binder, such as a resin binder.

I've used lot of this stuff in various applications. It doubles as a finish and a lube.
http://www.techplate.com/lubricant_solid_film.htm

I used it under the Mil Spec, MIL-PRF-46010, didn't care who made it as long as it met spec.
 
This topic would be interesting for people that design spacecraft. The vacuum of space would vaporize conventional greases, solid lubricants would hold up. Making parts move in space is a real challenge. Things we take for granted, i.e., door hinges and switches, would fail in space from cold welding. They work on earth because all of these material have a layer of adsorbed air.

Sputnik was designed to do nothing more than orbit the earth and send a beeping signal. The beeping signal failed after a short while because of this cold welding phenomenon, and all it sent was one long beep.
 
Quote:
They work on earth because all of these material have a layer of adsorbed air.

Interesting. Can you expound on this?

I believe Krytox grease is typically used for space applications now due to its unique properties.
 
I don't know the exact mechanism of this phenomenon, but I imagine that metals (and meybe other substances) have an affinity for air so that a very thin layer is held tight to the metal surface. This actually provides some lubricity that is unavailable in space. I read about this decades ago in school when looking through some NASA research studies of space materials from the early 60s. That's why spacecraft and sattelites are designed with as few moving parts as possible.
 
an excerpt from the above link:

Graphite is best suited for lubrication in a regular atmosphere. Water vapor is a necessary component for graphite lubrication. The adsorption of water reduces the bonding energy between the hexagonal planes of the graphite to a lower level than the adhesion energy between a substrate and the graphite. Because water vapor is a requirement for lubrication, graphite is not effective in vacuum.
 
DLC is great stuff as long as you can afford it. About 40% the hardness of diamond.

I want to have a gun or few coated eventually.
 
There was a "solid" lubricant we used in the navy on our SS valves. It was graphite suspended in alcohol. You brushed it on and let it dry, usually used two coatings...It was very good at keeping galling on the SS caps to a minimum when they were put on the SS valves. Can't remember the name but I still have a small bottle of it over 20 years later.
 
Originally Posted By: Tempest
DLC is great stuff as long as you can afford it. About 40% the hardness of diamond.I want to have a gun or few coated eventually.
motorsilk also has something for guns. check out their website. I'm thinking of getting some.
 
Originally Posted By: daves66nova
Originally Posted By: Tempest
DLC is great stuff as long as you can afford it. About 40% the hardness of diamond.I want to have a gun or few coated eventually.
motorsilk also has something for guns. check out their website. I'm thinking of getting some.


DLC is a vapor chamber coating. The motorsilk "gun oil" appears to be the same as their hydraulic oil. I'll pass.
 
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