WO2016183665A1

WO2016183665A1 - Composition and process for generating colloidally stable nanoparticle dispersions

Info

Publication number: WO2016183665A1
Application number: PCT/CA2016/000150
Authority: WO
Inventors: Andrew J. Myles; Alexander D. LANGILLE
Original assignee: National Research Council Of Canada
Priority date: 2015-05-21
Filing date: 2016-05-19
Publication date: 2016-11-24

Abstract

A nanoparticle dispersion is taught for use as an additive to a lubricant. The dispersion comprises nanoparticles having a primary particle size less than 500 nm and having a Moh's hardness greater than 7 and a branched chain fatty acid dispersant that is pourable at a temperature of from -30°C to 320°C, wherein the dispersion is colloidally stable. A method of making a nanoparticle dispersion is further taught, for use as an additive to a lubricant. The method involves reducing the particle size of a material having a Moh's hardness of greater than 7, to nanoparticles having a primary particle size less than 500 nm, adding a branched chain fatty acid dispersant to the nanoparticles and forming a colloidally stable nanoparticle dispersion. Methods for using the present nanoparticle dispersion are also taught.

Description

COMPOSITION AND PROCESS FOR GENERATING COLLOIDALLY STABLE NANOPARTICLE DISPERSIONS

FIELD OF THE INVENTION

The present invention relates to nanoparticle dispersions for use as lubricant additives. BACKGROUND

Lubrication is a critical factor in industrial processes and productivity and throughput of any moving part. Lubrication is also used as a method of controlling friction and heat. Failure of a lubricant often results in damaged equipment and a significant loss in both efficiency and profitability of a system. As applications demand higher temperatures and pressures, such as for example in steam-assisted gravity drain (SAGD) operations, lubricants must withstand these increasing harsh conditions while keeping costs low.

Lubricants come in three primary types: oils, greases, and solid lubricants. Oil is a thin liquid that offers a very low coefficient of friction between moving parts but tends to be quite heat sensitive. Grease is a viscous, semisolid liquid that has been thickened either by the use of a metal soap or an organoclay of some kind. The benefit of grease is its ability to remain in place and offer increased heat tolerance compared to the oil. The most significant drawback of either of these lubricants relates directly to the base material being used, which is oil, which cannot sustain temperatures in excess of 200°C for extended periods of time without suffering from decomposition.

Solid lubricants are particles or powders that can be made up of either hard or soft materials, as depicted on the Moh's hardness scale, as seen in Figure 1 and are typically metal or ceramic in nature. These particles offer limited thermal breakdown and are good for high temperature applications. Thin films of solid particles act as a sacrificial coating on the lubricated surface which helps to reduce friction and prevent wear to the surface.

There are three primary lubrication regimes within any lubricated system: hydrodynamic,

elastohydrodynamic, and boundary, as illustrated in Figure 2. Base oils and greases offer excellent performance and extremely low friction and wear under both hydrodynamic and elastohydrodynamic lubrication. The friction decreases as the continuous fluid film between the two opposing surfaces decreases and shifts from the hydrodynamic to the elastohydrodynamic regime. As the fluid film breaks, boundary lubrication begins, as illustrated in Figure 3. This often occurs at high pressure and low speed and is when the surfaces begin to come in contact with each other. This regime relies on surface chemistry for lubrication and is where solid lubricants, specifically nanolubricants, are most beneficial and effective.

Solid nanoparticles in lubricants act in one of two specific ways to aid in lubrication:

1. Hard nanoparticles (Moh's hardness > 7) must be smaller than half the size of the surface aberrations, less than 500nm in most cases, in order to be effective. These act as ball bearings that roll over one another and aid in filling surface deformities to reduce friction.

2. Soft nanoparticle lubricants (Moh's hardness <3) operate in a very different manner than hard particles. These particles typically have a layered structure that breaks up under the application of pressure. As these particles are crushed they help to absorb extreme pressure and the remnants may adhere to the lubricated surfaces, significantly reducing friction and surface wear.

In many oil field operations where conventional grease is used, temperatures in the pipes may reach or exceed 350°C while being under extreme pressure, leading to decomposition and breakdown of the grease. Currently, grease manufacturers add various heavy metal additives and softer nanoparticles in attempt to remedy these situations.

Some examples of such soft nanoparticle additives can be seen in, for example US 8,492,319 to Malshe and US 2014/0024565, also to Malshe.

While metal additives and metal nanoparticles reduce grease decomposition under high temperature and pressure, heavy metal such as lead are harmful to the environment. Furthermore, in high contact, high pressure scenarios, softer, metallic nanoparticles tend to compress and form a metal layer on the components being lubricated, which layer may or may not be desired.

SUMMARY

A nanoparticle dispersion is taught for use as an additive to a lubricant. The dispersion comprises nanoparticles having a primary particle size less than 500 nm and having a Moh's hardness greater than 7 and a branched chain fatty acid dispersant that is pourable at a temperature of from -30°C to 320°C, wherein the dispersion is colloidally stable.

A method of making a nanoparticle dispersion is further taught for use as an additive to a lubricant. The method comprises the steps of reducing the particle size of a material having a Moh's hardness of greater than 7, to nanoparticles having a primary particle size less than 500 nm, adding a branched chain fatty acid dispersant to the nanoparticles and forming a colloidally stable nanoparticle dispersion. A method is also taught for using the present nanoparticle dispersion, comprising the steps of mixing the nanoparticle dispersion with the lubricant and applying mixture to surface to be lubricated.

A method is further taught for using the present nanoparticle dispersion, comprising the steps of applying the nanoparticle dispersion to a surface to be lubricated and applying the lubricant over the nanoparticle dispersion.

It is to be understood that other aspects of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein various embodiments of the invention are shown and described by way of illustration. As will be realized, the invention is capable for other and different embodiments and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the present invention. Accordingly the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS A further, detailed description of the invention will follow by reference to the following drawings of specific embodiments of the invention. The drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. In the drawings:

Figure 1 is a diagram of a Moh's hardness scale;

Figure 2 is a schematic diagram of common lubrication regimes;

Figure 3 is a schematic of solid lubricants used in a boundary lubrication regime;

Figure 4 is a graph depicting time vs. particle size vs. zeta potential for ball milling of SiN nanoparticle aggregates with Isostearic Acid-N:

Figure 5 is a photograph of silicon nitride nanoparticles on the surface of a calcium sulfonate grease fiber;

Figure 6 illustrates the lowest obtained friction from high temperature wear testing using a varying concentration of one embodiment of the present nanoparticle dispersion additive;

Figure 7 illustrates t torque and tension test results of calcium sulfonate grease vs. the same grease with 0.5% of one embodiment of the nanoparticle dispersion additive of the present invention;

Figure 8 illustrates torque tension test results of the grease with 0.5% of one embodiment of the nanoparticle dispersion additive of the present invention vs. API modified grease; and Figure 9 is a schematic diagram of one embodiment of a method of the present invention.

The drawing is not necessarily to scale and in some instances proportions may have been exaggerated in order more clearly to depict certain features.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

The description that follows and the embodiments described therein are provided by way of illustration of an example, or examples, of particular embodiments of the principles of various aspects of the present invention. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the invention in its various aspects.

The present invention relates to nanoparticles and nanoparticle dispersions and their use in additives for lubricants. More specifically, the present invention relates to a colloidally stable dispersion of nanoparticles.

Nanoparticle dispersions used as lubricant additives have been found by the present inventors to show a number of advantages over conventional oil or grease lubricants used on their own. The nanoparticles used in the present invention are environmentally friendly while showing high levels of performance. Further to being environmentally friendly, it is also desirable that the nanoparticle be of an appropriate hardness, chemically inert, environmentally stable, readily available and low in cost. Hard nanoparticles are preferably used for the purposes of the present invention. More preferably, the nanoparticles of the present invention have a Moh's hardness of greater than 7. Hard nanoparticles that may be used for the purposes of the present invention include, but are not limited to, detonation nanodiamond, cubic boron nitride and ceramic particles such as but not limited to silica fume, fumed silica, and silicon nitride.

Most preferably, silicon nitride nanoparticles are used in the present invention, including both SiN and Si₃N₄. Silicon nitride has a sufficient hardness (8.5 Moh's hardness) for lubrication applications; it is environmentally benign and inexpensive. Silicon nitride nanoparticles have been found by the present inventors to be effective as extreme pressure lubricant additives, as they can withstand very high pressures and are highly thermally stable. Further advantageously, silicon nitride is completely inert and can therefore possibly be used as a food grade product.

Nanoparticles used in the present invention are less than 500 nm in primary particle size. For the purposes of the present invention, the term primary particle size refers to an average particle size, including in the case of agglomerated particles, the average agglomerated particle size. Primary particle size for the purposes of the present invention refers to particle or agglomerated particle diameter. Preferably, the nanoparticles range in primary particle size from 100-400 nm. Most preferably 150-350 nm primary particle size nanoparticles are used for the present invention.

The present nanoparticle primary particle size range is preferably smaller than half the size of common surface aberrations found on the components to be lubricated. This allows the nanoparticles to fill in surface aberrations to reduce friction and act as ball bearings that roll over one another. The present nanoparticle primary particle size range is also large enough to maintain a space between moving parts, thus providing a barrier of protection in the form of boundary lubrication when the surfaces begin to come in contact with each other.

Nanoparticles are often commercially available in size ranges of 15-70 nm. Furthermore, there is a tendency, due to high surface energy, for commercially available nanoparticles of such small size to agglomerate or clump into much larger primary particle sizes which can be up to 2-3 micrometers. Such large clumps are also not suitable for dispersion or lubricant additive purposes, as they are not useful in boundary lubrication.

The present nanoparticles can therefore be milled, ground, ultrasonicated or otherwise reduced in size to reach the preferred size range, more details of which are discuss below.

To improve dispersion of the nanoparticles in oil or grease, and to reduce surface polarization and surface energy of the high surface area nanoparticles, the surfaces of the nanoparticles are preferably modified with a dispersant, surfactant or coating. Any suitable dispersant may be used for such purposes and it is preferable to use a dispersant that is liquid at room temperature, pourable, thermally stable, chemically inert, readily available, environmentally friendly and inexpensive.

The dispersant acts to either inhibit surface energy of the nanoparticles or react with said surface energy to thereby block it. The present dispersants preferably do not intercalate into the nanoparticles. That is, there is no insertion of the dispersant into or within a surface porosity of the nanoparticles. Instead, the present dispersants serve to coat or encapsulate the particles.

The dispersants of the present invention can include fatty acids, fatty alcohols and other lipid-based materials and combinations thereof. Preferably, the present invention includes fatty acids having from about 4-40 carbon atoms, more preferably from 10-30 carbon atoms and most preferably from 15-25 carbon atoms. It is also possible and fully encompassed in the present invention to mix dispersants having carbon chains longer than 40 carbon atoms with dispersants having a smaller carbon length. Linear aliphatic carboxylic acids, such as octanoic acid, are one example of dispersants that can be used with the present invention. Branched chain fatty acids, and more preferably branched aliphatic carboxylic acids, such as isostearic acids in all its forms are also examples of dispersants that can be used with the nanoparticles of the present invention. One example of an isostearic acid that can be used in the present invention is iso- octa-decanoic acid, such as isostearic acid-N™ as shown below:

CH₃ H— COOH

Another example of useable isostearic acids are Prisorines™ manufactured by C ODA Lubricants. More preferably, branched chain fatty acids are used in the present invention. The inventors note that the branched nature allows for more thorough coating of the spherical surface of the nanoparticles.

Furthermore, the temperature range in which branched chain fatty acids can be used as a dispersant is greater than their linear counterparts. The branched chain fatty acids of the present invention remain in liquid state from -30°C until they reach their boiling points, which is typically commonly over 300°C and often between 310-320°C. The present branched chain fatty acids show good flowability and lower viscosity even at low temperatures, making them suitable for winter and outdoor storage and use. For example, the inventors have found that the present branched chain fatty acids have shown viscosities of 100 cps and lower at 30°C. The present branched chain fatty acid dispersants also show good pourability, thereby providing ease of addition and mixing of the present nanoparticle dispersion additives to oil and/or grease lubricants.

Linear chain fatty acids tend to be waxy until they reach their melting point of about 16°C, and they also boil at about 230°C, and so limited to lubricating applications within these ranges. It is possible and fully contemplated by the present invention to use a combination of branched and linear chain fatty acids in any ratio as a dispersant. By mixing linear and branched chain fatty acids it is possible to reach the desired viscosity and pourability for a particular application while minimizing costs.

Isostearic acid-N is most preferred for use as a dispersant for the present invention. In addition to showing good pourability and availability, isostearic acid-N is also fully inert and food grade. A number of means of making the present nanoparticle dispersions are possible including orbital ball mill, ultrasonication, bead-assisted-sonic-disintegration (BASD) and high-shear mixing, and alternate methods of preparing dispersions and reducing particle size, and are encompassed by the scope of the present invention. Typically nanoparticles are fed to the size reducing equipment together with the dispersant as a single step process; although it is also possible to reduce size of the nanoparticles first then mix the size-reduced nanoparticles into the dispersant. A single step process preferred.

More preferably, the nanoparticles are ball milled. One embodiment of a method of making the present nanoparticle dispersion is illustrated in Figure 9.

In one embodiment, an orbital ball mill with various sizes of zirconium oxide beads was used to create stable nanoparticle dispersions. Preferably zirconium oxide beads ranging in size from 0.1-10 mm were used. In this embodiment, the nanoparticles can be directly added to the branched chain fatty acid at different stoichiometric ratios and milled for specific time periods to achieve stable nanoparticle dispersions. The nanoparticle dispersion can then be tested for average particle size and zeta potential. Zeta potential is a measure of colloidal stability of the nanoparticle dispersion additive within the lubricant or other medium. Zeta potential is measured in millivolts and is an indication of a particle's surface charge. A high charge, either negative or positive, indicates good surface charge and hence good repulsion of neighbouring particles, reducing the chances of aggregation. The present nanoparticle dispersion have an average zeta potential over +/-80 mV, and more preferably over +/100 mV.

The high colloidal stability of the nanoparticle dispersion is advantageous in that the dispersion can be stored for long periods of time before adding it to a lubricant without the nanoparticles settling out of dispersion. Good colloidal stability can also be observed generally based on performance, pourability, and visual inspection of the dispersion additive. It is also possible to mix the present nanoparticle dispersion additive with a lubricant and then store the mixture.

Most preferably, the nanoparticle dispersion is ball milled using 1mm zirconium oxide beads, using a stoichiometry of fatty acid to particles of from 10:1 to 2:1 and most preferably at a fatty acid to nanoparticle stoichiometry of 5:1.

The present nanoparticle dispersion enhanced lubricants show a stable structure of intact grease fibers with nanoparticles deposited on their surface, as seen in Figure 5. The present nanoparticle dispersion additives show chemical inertness and do not degrade the grease fibres of the lubricant. Friction characterizations of the effectiveness of the present nanoparticle dispersions in grease lubricants when measured with a wear tester show that at high pressure, the coefficient friction is lower in samples with nanoparticle additive.

Figure 6 illustrates the coefficient of friction measured at two different boundary or contact friction loadings and for various weight percentage concentration of the present nanoparticle dispersion additive in a grease lubricant. The test conditions of the plot are at a temperature of 150°C and the friction load is indicated in the legend. It has been observed that the coefficient of friction decreases as weight percentage of the nanoparticle additive is increased from nothing to about 0.6% w/w.

The weight percentage of nanoparticle dispersion additive in an oil or grease lubricant can be from 0.01 % w/w up to 5.0 %w/w, more preferably from 0.1% w/w to 3.0% w/w and most preferably 0.5 % w/w to 1.5 %w/w.

The present nanoparticle additives can be used in greases for applications as a threading compound. Figure 7 illustrates a lower coefficient of friction seen when the nanoparticle dispersion additive is present in a non-lead based grease lubricant, as a product of the frictional load in pounds and the degree of makeup of the components being threaded together.

When performance of a non-lead based grease containing the present nanoparticle dispersion additive was compared to grease containing heavy metals, surprisingly at higher loads between 22000psi and 50000psi the two greases exhibit a near identical coefficient of friction, as seen in Figure 8. Thus the present nanoparticle dispersion additive can therefore be added to safer, non-lead based grease and replace undesirable heavy metal based lubricants while still meeting similar performance in high temperature and high pressure applications.

The nanoparticle dispersion additives of the present invention may be added to lubricants in any number of different ways. In one embodiment, the present nanoparticle dispersion additive is dispersed within the oil or grease lubricant and mixed, stirred, or combined by any form of mechanical mixing, including high shear mixing. This mixture can then be used immediately or stored for future use.

It is also possible to apply the present nanoparticle dispersions directly to a surface to be lubricated, for example by brushing, spraying or otherwise, and then to apply the lubricant separately onto the nanoparticle dispersion. In such cases, the nanoparticle dispersion may form a first layer and the lubricant may form a second layer on top of the first layer. Alternatively, the nanoparticle dispersion may at least partially mix with the lubricant to form an at least partially mixed or comingled layer. Furthermore, it is further possible to include any number of other solid materials or particles to the present nanoparticle dispersion. Such other solid materials can be nanoparticles or larger particles, they can be harder than the nanoparticles of the present invention, or they can be softer. Examples of preferred solid materials or particles that can be added with the present invention include graphite particles or hexagonal boron nitride particles.

In addition to the dispersant or surfactant, further liquid or semi-liquid materials can be added to the nanoparticle dispersion of the present invention. Such materials can include but are not limited to plasticizers, thickeners, extreme pressure additives in general, anti-wear additives in general, colourants dies and any combinations thereof.

A number of further methods for making the present nanoparticle dispersions are possible and are encompassed by the scope of the present invention. These methods include high shear mixing and large scale ball mills similar to those used in the cement industries. A preferred method for future scale up is high shear mixing, more preferably in an inline process, which increases productivity and quantity of nanoparticle dispersion created, allowing scale up.

Examples:

Example 1:

Isostearic acid-N dispersant was directly mixed with silicon nitride nanoparticles at a stoichiometric ratio of 5:1 and ball milled with 1 mm zirconium oxide beads in 30 second to 1 minute on-off cycles over the course of 8 hours. It would be well known by a person of skill in the art that a number of variables in the ball milling could be altered to optimize the process including ratio of dispersant to particles, speed of the ball mill, temperature of operation, cycling times, among other and all such variations are included in the scope of the present invention.

The nanoparticle additive dispersion was then mixed into a hexane to conduct dynamic light scattering (DLS) testing to determine particle size and zeta potential. Particle size data was corroborated by conducting acoustic particle sizing, which measures the attenuation of ultrasound at set frequencies, on the nanoparticle additive dispersion in HT-4 oil. This attenuation spectrum is the raw data used for calculating a particle size distribution using well-known theorums to extract particle size distributions from attenuation spectra. Characterization of the nanoparticle dispersion in oil indicated an average particle radius across three runs to be 169.3nm, meaning an average primary particle size of 340 nm, with a zeta potential average of greater than -100 mV. Tribological properties were tested by mixing the nanoparticle additive dispersion in grease

Example 2

A nanoparticle dispersion was ball milled using 1mm zirconium oxide beads. A 5:1 fatty acid to SiN stoichiometry was milled for 8 hours. Particle sizing of the nanoparticles dispersion additive in hexane was measured with a dynamic light scattering machine (DLS), which also took zeta potential readings. A zeta potential of -116mV was achievable and reproducible, as illustrated in Figure 4. Particle size data was then corroborated by an acoustic particle sizer used on the nanoparticles dispersion additive in oil. The corroborated results showed an average particle size of 300-400 nm, as illustrated by the 150 -200 nm radii shown in Figure 4. Friction testing was then conducted with the nanoparticle dispersion additive in grease, to confirm predetermined lubricating characteristics. This process was scaled from grams to hundreds of grams with identical results, providing evidence of scalability.

The inventors note from Figure 4 that while, as expected, zeta potential increases with decreasing particle size due to increased surface area for surface charge, the zeta potential was further increased even when the nanoparticles had been ground to a final size. This further increase in zeta potential is hypothesized to be due to further mixing of the dispersant with the nanoparticles to surface coat the particles and aid in dispersion and colloidal stability.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to those embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the full scope consistent with the claims, wherein reference to an element in the singular, such as by use of the article "a" or "an" is not intended to mean "one and only one" unless specifically so stated, but rather "one or more". All structural and functional equivalents to the elements of the various embodiments described throughout the disclosure that are known or later come to be known to those of ordinary skill in the art are intended to be encompassed by the elements of the claims.

Claims

1. A nanoparticle dispersion for use as an additive to a lubricant, said dispersion comprising: a. nanoparticles having a primary particle size less than 500 nm and having a Moh's hardness greater than 7; and

b. a branched chain fatty acid dispersant that is pourable at a temperature of from -30°C to 320°C

wherein the dispersion is colloidally stable .

2. The nanoparticle dispersion of claim 1, wherein the nanopoarticles are silicon nitride

nanoparticles.

3. The nanoparticle dispersion of claim 3, wherein the nanoparticles range in primary particle size from 100-400 nm.

4. The nanoparticle dispersion of claim 1, wherein the branched chain fatty acid is branched aliphatic carboxylic acid.

5. The nanoparticle dispersion of claim 4, wherein the branched chain aliphatic carboxylic acid is an isostearic acid.

6. The nanoparticle dispersion of claim 5, wherein the isostearic acid is iso-octa-decanoic acid.

7. The nanoparticle dispersion of claim 1, wherein the nanoparticle dispersion has an average zeta potential greater than +/-80 mV.

8. The nanoparticle dispersion of claim 7, wherein the nanoparticle dispersion has an average zeta potential greater than +/-100 mV.

9. The nanoparticle dispersion of claim 1, wherein the branched fatty acid is present with the nanoparticles in a ratio of from 10:1 to 2:1.

10. The nanoparticle dispersion of claim 9, wherein the branched fatty acid is present with the nanoparticles in a ratio of 5:1.

11. The nanoparticle dispersion of claim 1, wherein dispersion is added to a lubricant in a weight percentage of nanoparticle dispersion to lubricant of from 0.01 % w/w to 5.0 %w/w.

12. The nanoparticle dispersion of claim 11, wherein dispersion is added to a lubricant in a weight percentage of nanoparticle dispersion to lubricant of from 0.1% w/w to 3.0% w/w.

13. The nanoparticle dispersion of claim 12, wherein dispersion is added to a lubricant in a weight percentage of nanoparticle dispersion to lubricant of from 0.5 % w/w to 1.5 %w/w .

14. The nanoparticle dispersion of claim 1, further comprising additional solid materials.

15. The nanoparticle dispersion of claim 14, wherein the additional solid materials are selected from the group consisting of nanoparticles and larger than nano-sized particles.

16. The nanoparticle dispersion of claim 14, wherein the additional solid materials have a hardness that is selected from the group consisting of harder than the nanoparticles and softer than the nanoparticles.

17. The nanoparticle dispersion of claim 14, wherein the additional solid materials are graphite particles.

18. The nanoparticle dispersion of claim 1, further comprising additional liquid or semi-liquid

materials added to the nanoparticle dispersion.

19. The nanoparticle dispersion of claim 18, wherein the liquid or semi-liquid materials are selected from the group consisting of plasticizers, thickeners, extreme pressure additives, anti-wear additives, colourants, dies and combinations thereof.

20. A method of making a nanoparticle dispersion for use as an additive to a lubricant, said method comprising the steps of: a. reducing the particle size of a material having a Moh's hardness of greater than 7, to nanoparticles having a primary particle size less than 500 nm in the presence of a branched chain fatty acid dispersant to form a colloidally stable nanoparticle dispersion.

21. The method of claim 20, wherein reducing particle size comprises a method selected from the group consisting of orbital ball milling, ultrasonication, bead-assisted-sonic-disintegration (BASD) and high-shear mixing.

22. The method of claim 20, wherein reducing particle size comprises orbital ball milling.

23. The method of claim 22, wherein ball milling is conducted with zirconium oxide beads having a bead size of from 0.1 to 10 mm.

24. The method of claim 20, wherein the branched chain fatty acid is present at a ratio of from 10:1 to 2:1 branched chain fatty acid to particles.

25. The method of claim 24, wherein the branched chain fatty acid is present at a ratio of 5:1

branched chain fatty acid to particles.

26. The method of claim 20, further comprising mixing nanoparticle dispersion into a lubricant that is selected from oil, grease and combinations thereof.

27. The method of claim 26, wherein the nanoparticle dispersion is mixed with the lubricant in a weight percentage of nanoparticle dispersion to lubricant of from 0.01 % w/w to 5.0 %w/w.

28. The method of claim 27, wherein the nanoparticle dispersion is mixed with the lubricant in a weight percentage of nanoparticle dispersion to lubricant of from 0.1% w/w to 3.0% w/w.

29. The method of claim 28, wherein the nanoparticle dispersion is mixed with the lubricant in a weight percentage of nanoparticle dispersion to lubricant of from 0.5 % w/w to 1.5%w/w.

30. The method of claim 26, wherein the nanoparticle dispersion is mixed with the lubricant and then stored.

31. The method of claim 20, further comprising adding additional solid materials to the nanoparticle dispersion.

32. The method of claim 31, wherein the additional solid materials are graphite particles.

33. The method of claim 20, further comprising adding additional liquid or semi-liquid materials to the nanoparticle dispersion.

34. The method of claim 33, wherein the liquid or semi-liquid materials are selected from the group consisting of plasticizers, thickeners, extreme pressure additives, anti-wear additives, colourants, dies and combinations thereof.

35. A method for using the nanoparticle dispersion of claim 1, comprising the steps of:

a. mixing the nanoparticle dispersion with the lubricant; and

b. applying mixture to a surface to be lubricated.

36. A method for using the nanoparticle dispersion of claim 1, comprising the steps of:

a. applying the nanoparticle dispersion to a surface to be lubricated; and

b. applying the lubricant over the nanoparticle dispersion.

37. The method of claim 36, wherein the nanoparticle dispersion and the lubricant form separate layers on surface to be lubricated

38. The method of claim36, wherein nanoparticle dispersion at least partially mixes with the lubricant to form an at least partially mixed layer on the surface to be lubricated.