Ceratec, MoS2, and other particle suspension.

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I have a question that's been on my mind for a while now. You have these additives that rely on suspended particles to reduce wear numbers. But what I don't understand, is how do these fine particles, particularly in ceratec (since ceramic is pretty hard), not act as a microabrasive against soft parts like bearings?
 
I'm not extremely versed on liquid/solid interactions at the nanometer level, but when you're talking about something that measures in billionths of a meter, flowing through gaps that are thousandths of a meter, it sounds like driving a go-kart through an open jumbo jet hangar door.
 
While I see your, logic, I'm still not super clear on how it works.

I'll use ceratec to talk about. Particle size there is .4 microns, or .016 thousands of an inch. And the outline below indicates that lubricating film can thin down to .2 microns, thinner than the particle size of this stuff. How does it not grind into and abrade the bearings and other surfaces?

http://www.sciencedirect.com/science/article/pii/S0924424708004834
 
Indian phd student... Suddenly they are mechanical engineer extraordinaire? How many engines has he designed?

At .2 microns your oil film is essentially gone. Bearing clearances typically offer more cushion.

Moly works. This ceratec business is probably something like graphite. Which technically could be called a ceramic by the marketing dorks.

Looking at liquidity site and MSDS offers nothing. So marketing babble it is then...
 
Originally Posted By: SnowDrifter
Particle size there is .4 microns, or .016 thousands of an inch.


.4 microns does NOT equal .016"... prob closer to .00016"?
 
Originally Posted By: Linctex
Originally Posted By: SnowDrifter
Particle size there is .4 microns, or .016 thousands of an inch.


.4 microns does NOT equal .016"... prob closer to .00016"?


Thousandths sir
grin.gif
 
Originally Posted By: SnowDrifter
I have a question that's been on my mind for a while now. You have these additives that rely on suspended particles to reduce wear numbers. But what I don't understand, is how do these fine particles, particularly in ceratec (since ceramic is pretty hard), not act as a microabrasive against soft parts like bearings?


Hexagonal boron nitride aka white graphite.

https://en.wikipedia.org/wiki/Boron_nitride
 
Originally Posted By: Linctex
Originally Posted By: SnowDrifter
Particle size there is .4 microns, or .016 thousands of an inch.


.4 microns does NOT equal .016"... prob closer to .00016"?


1.574803149606299e-5 inches. you're off by an order of magnitude
 
Help if any would be in the metal to metal contact otherwise it is of no advantage.
 
The nano particles fill the nano ridges and crevices on the surface and bond to the metal I believe.
 
http://www.imoa.info/molybdenum-uses/molybdenum-chemistry-uses/lubricants.php



Molybdenum disulfide is used as a dry lubricant in, e.g. greases, dispersions, friction materials and bonded coatings.

Molybdenum-sulfur complexes may be used in suspension but more commonly dissolved in lubricating oils at concentrations of a few percent.

Molybdenum disulfide, MoS2, the most common natural form of molybdenum, is extracted from the ore and then purified for direct use in lubrication. Since molybdenum disulfide is of geothermal origin, it has the durability to withstand heat and pressure. This is particularly so if small amounts of sulfur are available to react with iron and provide a sulfide layer which is compatible with MoS2 in maintaining the lubricating film.

A number of unique properties distinguish molybdenum disulfide from other solid lubricants:

A low coefficient of friction (0.03-0.06) which, unlike graphite, is inherent and not a result of absorbed films or gases;
A strong affinity for metallic surfaces;
Film forming structure;
A yield strength as high as 3450 MPa (500 x 103 psi);
Stability in the presence of most solvents;
Effective lubricating properties from cryogenic temperatures to about 350oC in air (1200oC in inert or vacuum conditions).
Molybdenum disulfide will perform as a lubricant in vacuo where graphite fails.

A combination of molybdate and water soluble sulfides can provide both lubrication and corrosion inhibition in cutting fluids and metal forming materials. Oil soluble molybdenum-sulfur compounds, such as thiophosphates and thiocarbamates, provide engine protection against wear, oxidation and corrosion. Several commercial manufactures supply these additives to the lubrication industry.

Some molybdenum disulfide formulations are given in Table 1.
 
Originally Posted By: CT8
Help if any would be in the metal to metal contact otherwise it is of no advantage.


Less oil leakageout the side of the bearings when oil gets very hot, which translates into higher oil pressure. This because the particles dont shear or thin by temperature or pressure and end up hindering flow out of the bearing at some point.
 
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