EP2714866B1 - Use of nanoparticles in a composition to improve fatigue life and pitting on the surface of a drive train - Google Patents

Description

The present invention relates to the use of nanoscale materials in a composition applied to their surfaces to prevent fatigue damage in drive elements. In particular, this order protects the surfaces of drive elements against the formation of gray staining, surface fatigue, micro-pitting and pitting. The occurrence of fatigue damage on these surfaces is thereby prevented or reduced.

1. 1) Fressen und Verschleißen, bei denen die Schädigung von der Oberfläche der Kontaktflächen ausgeht.
2. 2) Ermüdungsschäden, die ihren Ausgang im Gefüge unterhalb der belasteten Flächen nehmen und letztendlich in Ausbrüchen, wie beispielsweise Pitting, Grauflecken, Grübchenbildung, enden.

For drive elements, two types of damage occur in the case of excessive mechanical loads:

1. 1) seizure and wear, where the damage originates from the surface of the contact surfaces.
2. 2) fatigue damage, which starts in the structure below the loaded surfaces and ends up in outbreaks, such as pitting, gray pitting, pitting.

To reduce wear and tear there are a variety of additives and solid lubricants that are well known and widely used.

To prevent fatigue damage very few effective measures are known. One measure is the increase of the lubricating film thickness.

Fatigue wear (pitting) results from local overloading of the material due to periodic compressive stress. The fatigue of the material becomes visible through gray staining, surface fatigue, mirco-pitting or pits on the surface of the material. At first 20 to 40 μm below the surface, fine cracks develop in the metal mesh, which lead to material eruptions. The small microscopic visible flaws on the tooth flank, referred to as micro-pittings or pitting, can be recognized as dull gray areas. For gear teeth, gray spots on tooth flanks can be observed in virtually all speed ranges. Even in rolling bearings very shallow eruptions occur in the area of the sliding contact as gray patches on the raceway These relationships are described in detail in the DE 10 2007 036 856 A1 and the literature cited therein.

In order to improve the viscosity properties, different additives are used in lubricants in order to avoid or at least minimize the above-mentioned damage in rolling bearings, gears, gears and the like. Here, the fatigue damage referred to as gray pitting and pitting are those which are the most severe material damage from the resulting cracks.

• Senkung der Kontaktkräfte,
• geeignete Auswahl des Schmiermittels,
• ausreichende Schmiermittelzufuhr,
• günstige Positionierung und Gestaltung der Schmierstellen,
• Vermeidung von Zuständen ohne Schmierung.

To avoid this fatigue damage, the following measures can be taken:

• Lowering the contact forces,
• suitable selection of the lubricant,
• adequate lubricant supply,
• favorable positioning and design of the lubrication points,
• Avoiding conditions without lubrication.

To avoid fatigue, various investigations have been made, among other things, attempts to improve the lubricity of lubricants by adding various additives. In particular, additives have been investigated which can reduce the friction between the components or which have an improved viscosity.

That's how it describes DE-OS 1 644 934 Organophosphates as additives in lubricants added as anti-fatigue additives.
The already mentioned above DE 10 2007 036 856 A1 discloses the addition of polymers with ester groups used as antifatigue additives in lubricants.
The WO 2008/127395 discloses the use of CeO2 nanoparticles in a mineral oil-based lubricant to reduce pitting. These nanoparticles are stabilized by means of a nanoparticle stabilizer.

From the US 2003/0092585 A1 Thiazoles are known as anti-pitting additives.
The EP 1 642 957 A1 relates to the use of MoS ₂ and molybdenum dithiocarbamate, which are used as additives in propellant wave urea fats.

The additives known from the prior art described above, such as organophosphates and thiazoles, are not thermally stable as organic substances. In addition, they can evaporate under the operating conditions or can react as a classic anti-wear additives, especially with the metal surfaces, ie they predominantly react on the touching roughness peaks, since there by the flash temperatures occurring sufficient energy for a chemical reaction with the metallic Friction layer is present. Therefore, they can at most act as subordinate anti-pitting additives. Solid lubricants, such as molybdenum disulfide, on the other hand, have a tendency to precipitate out due to their density

Settle oil formulations and may also have a corrosive effect. Since the solid particles are used with particle sizes in the micron range, there is a strong influence on the flow behavior and an increase in viscosity and a deviation from Newton's flow behavior. This behavior degrades the availability of the additive in the lubrication gap. SEM investigations on the surfaces of the metallic friction partners show that these structures or depressions have dimensions of well below 1 μm. These depressions are not accessible to the μm-sized solid lubricant particles.

Starting from the prior art, the object of the present invention is to provide a composition which can be applied to the surfaces of drive elements so as to prevent or reduce the fatigue phenomena "gray spots" and "pitting" on these drive elements. The composition should contain no volatile organic compounds as an anti-pitting additive and the anti-pitting additives should be in a liquid phase with Newton shem flow behavior. Thus, they can penetrate into the structures or depressions described above and there reinforce the metal structure.

The subject of the present invention is therefore the use of a composition which is applied to the surface of the drive elements in order to prevent or avoid fatigue phenomena. It has surprisingly been found that the application of a composition containing surface-modified nanoparticles and a carrier material prevents or prevents the fatigue damage, such as gray pitting and pitting.

The surface-modified nanoparticles contained in the composition are oxidic nanoparticles. They can be selected from silica, zinc oxide and alumina. For surface modification, surface modification reagents such as alkyl, aryl, Alkylarylsilanes having at least 1 to 3 of these alkyl, aryl or alkylaryl groups, which may additionally contain functional groups, in particular thio groups, phosphate groups and which are used individually or in combination. The optionally present thio or phosphate groups can additionally undergo a reaction with the metal surface to be protected. In the surface modification, the amount of modifying reagent per nm ^{2 of} the particle surface is 0.1 to 10 molecules of the modifying reagent, preferably 0.3 to 5 molecules. This chemical modification causes the nanoparticles in different base oils monopartite, ie without aggregation.

It has also been found that the composition may contain mixtures of nanoparticles which are both different from one another and have different particle sizes.

The surface-modified nanoparticles have an average particle size of 10 nm to less than 200 nm, preferably 10 nm to 100 nm. The particle size of nanoparticles can be determined by different methods. Dry methods such as transmission electron microscopy often provide smaller particle sizes than the dynamic light scattering measurement, as in the latter method a relatively tightly bound solvent envelope requires larger values. The particle size data in this application are generally related to dynamic light scattering results.

The carrier material is selected from the group consisting of mineral oils, synthetic hydrocarbons, polyglycols, esters and ester compounds, PFPE, native oils and derivatives of native oils, aromatic oils such as phenyl ethers and mixtures thereof. Polygkycols, esters and synthetic hydrocarbons are particularly preferably used as carrier material.

The composition of the present invention containing the nanoparticles and the carrier may further be incorporated into a lubricant become. This lubricant may be in the form of fats, pastes, oils and is selected from the group consisting of a lubricating oil or mixtures of lubricating oils, polyglycols, silicone oils, perfluoropolyethers, mineral oils, esters, synthetic hydrocarbons, phenyl ethers, native oils and derivatives of native oils. organic or inorganic thickeners, in particular PTFE, graphite, metal oxides, boron nitride, molybdenum disulfide, phosphates, silicates, sulfonates, polyimides, metal soaps, metal complex soaps, ureas and mixtures thereof, solid lubricants such as graphite, MoS ₂ .

Particularly preferred are compositions which are used as a concentrate in one of the above-mentioned lubricants.

In addition, soluble additives, in particular aromatic amines, phenols, phosphates, as well as corrosion inhibitors, antioxidants, anti-wear agents, friction reducing agents, means for protection against metal influences, UV stabilizers may be present in the composition.

The composition of the invention according to claim 1 generally consists of 0.1 to 40 wt .-% surface-modified nanoparticles, in particular 2 to 20 wt .-% surface-modified nanoparticles, and 99.9% to 60% by weight of carrier material, in particular 8 to 80 Weight% carrier material.

The introduction of the nanoparticles into the carrier material can take place in two ways. On the one hand, dispersions of nanoparticles can be produced in a sol-gel process and surface-modified in the dispersion, and then the dispersion can be prepared by adding the support material and removing the volatile solvents. This process can be referred to as redispersing and has the advantage that the nanoparticles are always wetted by liquid and thus the risk of agglomeration is reduced. This method is described in the following examples.

Alternatively, after modifying the surfaces, the solvents may be removed and the dry particles isolated. By dispersing under shear and optionally elevated temperature, the particles can be incorporated. Which method is to be used depends on various factors such as particle type, particle sizes, type and extent of surface coverage and chemical nature of the carrier material and must be individually tailored.

This composition can then be incorporated into any lubricant so that, based on the final formulation of 0.1-10% nanoparticles, 99.9-90% lubricant.

Figur 1:

Teilchengrößenverteilung einer Charge von Levasil 200N/30%

Figur 2:

Teilchengröße der SiO₂ Dispersion, wobei die Teilchen mit dem Stöber Prozeß hergestellt und mit dyn. Lichtstreuung bestimmt wurden (Beispiel 1)

Figur 3:

Teilchengröße der SiO₂ Dispersion nach Funktionalisierung mit Butylsilan, die mit dyn. Lichtstreuung bestimmt wurde (Beispiel 2)

Figur 4:

Teilchengrößenverteilung in Polyglykol (Beispiel 4)

Figur 5:

Die rheologischen Eigenschaften der Nanoteilchen enthaltende Zusammensetzung basierend auf Polyglykol in Abhängigkeit vom Schergefälle (Beispiele 4 a bis d und Vergleichsbeispiel 4 e)

The illustrations below show:

FIG. 1:

Particle size distribution of one batch of Levasil 200N / 30%

FIG. 2:

Particle size of the SiO ₂ dispersion, wherein the particles prepared by the Stöber process and dyn. Light scattering were determined (Example 1)

FIG. 3:

Particle size of the SiO ₂ dispersion after functionalization with butylsilane, with dyn. Light scattering was determined (Example 2)

FIG. 4:

Particle size distribution in polyglycol (Example 4)

FIG. 5:

The rheological properties of the nanoparticle-containing composition based on polyglycol as a function of the shear rate (Examples 4 a to d and Comparative Example 4 e)

The preparation of SiO ₂ nanoparticles is described, for example, in: W. Stöber, A. Fink, Journal of Colloid and Interface Science 26, 62-69, 1968 or in: Zichen Wang et al. Materials Letters 61, 2007, 506-510 , The disadvantage of using the Stöber process in the production is that the resulting dispersions have low contents of SiO ₂ nanoparticles, as a rule about 3% by mass SiO ₂ . The stability of the nanoparticles and also the nature of the particles which form are determined by the choice of reaction conditions, in particular the pH.

There are also commercial sources of nanoparticulate SiO ₂ dispersions. Under the trade name Levasil (Akzo Nobel, formerly HC Starck) aqueous dispersions are offered with solids contents of up to 50%. For example, Levasil 200N / 30% is a 30% dispersion stabilized with ammonia. The particle size is given as about 55 nm. This size distribution is indicated by the diagram in FIG. 1 confirming the particle analysis with a Malvern Zetasizer.

Also available from Akzo Nobel under the trade name Bindzil are SiO ₂ nanodispersions with particle sizes around 10 nm and solids contents up to 40%, the surfaces of which are modified with epoxy silane.

The preparation of the aqueous dispersions is also in the EP 1 554 221 B1 and the EP 1 554 220 B1 described.

Example 1:

Process for the preparation of unmodified SiO ₂ nanoparticles from tetraethyl orthosilicate (Stöber method)

In a 2 l three-necked flask equipped with KPG stirrer and reflux condenser, 612.4 g of ethanol, 113.47 g of H ₂ O dest, 21.67 g NH ₃ (25%) are introduced and heated to reflux. A solution of 95.68 g of tetraethylorthosilicate in 156.77 g of ethanol is added slowly via a dropping funnel. After completion of the addition, the reaction solution is refluxed for an additional 4 hours with stirring. The result is an opalescent dispersion. The mean particle size is 52 nm, as in FIG. 2 is specified.

Example 2:

Functionalization of the surface of nanoparticles with a silanization reagent, which were prepared by the Stöberprozess according to Example 1

It is known that according to literature, for example those between 4 and 4, 6 SiOH groups per nm ² are to be expected on SiO ₂ surfaces ( Dissertation by M. Braun (contributions to the physico-chemical characterization of functional SiO 2 surfaces, TU Chemnitz, 2009 ). Of trialkoxyalkylsilanes or trialkoxyarylsilanes, this requires slightly more than one silane per nm ² of surface area of the SiO ₂ nanospheres to be functionalized. However, it is also possible to use higher or lower silane amounts.

Assuming that these are spherical particles, the specific surface area can be calculated in m ² / g: $$\mathrm{surface}\ddot{\mathrm{a}}\mathrm{che}=\mathrm{3000}/\left(\mathrm{Diameter\; nanospheres\; in\; nanometers}\right)$$

The dispersion prepared in Example 1 (277.87 g) is heated to 78 ° C under reflux with stirring. After reaching the temperature, 1.66 g of n-butyltrimethoxysilane are added in one shot. The solution is kept at 78 ° C. for a further 8 hours with stirring. FIG. 3 shows that the particle size distribution is maintained.

Example 3:

Incorporation of the functionalized nanoparticles into polyglycol

83.11 g of the dispersion of functionalized nanoparticles according to Example 2 are mixed with 28.10 g of water-miscible polyglycol (monomers ethylene oxide and propylene oxide, kinematic viscosity 100 mm ² / sec at 40 ° C.) in a rotary evaporator while heating with the oil bath to 100 ° C. and applying a vacuum, for example with a water jet pump, concentrated. The result is a clear liquid. The high dispersion to oil ratio is necessary in order to be able to produce concentrations of 10% nanoparticles in the polyglycol in the case of the low concentration of SiO ₂ particles on which the dispersions prepared in the Stöber process are based. This dispersion can also be measured by dynamic light scattering be, but must be diluted by addition of the base oil to a concentration of 1% SiO ₂ . FIG. 4 shows that the particle size is retained. The broadening of the peak can be explained by the higher viscosity of the polyglycol compared to the water / ethanol mixtures. The shift of the peak to larger particle diameter can be explained by the enlargement of the solvent envelope, since the polyglycol molecules occupy a larger space on the particle surface than water or ethanol.

Example 4:

Rheological properties of modified nanoparticles in polyglycol

According to the preceding examples, polyglycol dispersions are prepared which in all cases build on the dispersion of Example 1. As silanes, phenyltrimethoxysilane and triethoxy (octyl) silane were used in addition to butyltrimethoxysilane. It was modified with a silane per nm ² analogously to Example 2. In all cases, clear liquids result after redispersion. Table 1 shows that the kinematic viscosity is only slightly increased. The content of SiO ₂ is also shown at the higher density. <u> Table 1 </ u> Example 4a Example 4b Example 4c Example 4c 10% nanoparticles 10% 10% nanoparticles reference SiO ₂ . nanoparticles SiO2, polyglycol Phenyl-modified, in SiO ₂ , Butyl-modified, in Polyglycol, about 100 Oktylmodifiziert, Polyglycol, about 100 mm ² / sec in polyglycol, approx. mm ² / sec 100 mm ² / sec Appearance clear liquid clear liquid clear liquid clear liquid Stabinger viscometer Apparatus from Anton Paar, determination of kinematic viscosity in the sense of ASTM D 7042-04 / ASTM D 4 Viscosity 40 ° C (mm ² / s) 116.05 103.5 117.32 103.79 Viscosity 100 ° C (mm ² / s) 22.927 20.698 24.098 21,074 VI 228.7 222.6 238.5 230.6 Density 40 ° C (g / cm ³ ) 1.0415 1.0409 1.0516 .9877 Density 100 ° C (g / cm ³ ) .9953 0.9949 1.0058 .9334 Density 15 ° C (g / cm ³ ) 1,057 1.0562 1.0669 1.0058 translucent. Viscosity (mPa-s) 50mm cone / plate, shear rate 300 sec ^-1 iA DIN 51810 235 210 225 196

Table 1 shows the data of the 10% dispersions of the butyl silane, octyl silane and phenyl silane modified nanoparticles in polyglycol.

In addition, the dynamic viscosity of the nanoparticle-containing oils was determined as a function of the shear rate using a cone / plate system on the rheometer. The shear rate is increased logarithmically from 50 sec ^-1 to 5000 sec ^-1 . In the case of the three dispersions described above, the dynamic viscosity remains independent of the shear rate, so it is observed Newtonian flow behavior (see FIG. 5 ). In contrast, a 10% dispersion of Aerosil OX 50 (hydrophilic fumed silica BET 35 - 65 m ² / g from Evonik, according to the manufacturer, a mean primary particle size of 40 nm and thus similar to the investigated nanoparticles) in the same polyglycol a clear Decrease in viscosity with shear ( FIG. 5 ).

The aerosil-containing mixture, which in FIG. 5 4e, thus showing a pronounced deviation from Newton's flow behavior, which can be explained by an interaction of the unmodified particles.

Example 5

Functionalization and redispersion from Levasil 200N / 30%

404 g of Levasil 200N / 30% are heated to about 85 ° C. with stirring. 395 g of ethanol and 11.78 g of butyltrimethoxysilane (corresponds to about 5 silane molecules per nm ² surface area) are added in one shot and kept at the temperature for about 1 h with stirring. Already in the heat forms a gel-like consistency.

21.06 g of the gel are redispersed with 81.89 g of polyglycol oil as described above. The result is a clear liquid (about 3.8% SiO ₂ ). <u> Table 2 </ u> Example 5 reference example 3.8% butyl-functionalized Pure polyglycol oil SiO ₂ nanoparticles in polyglycol Appearance clear liquid clear liquid Stabinger viscometer Apparatus from Anton Paar, determination of kinematic viscosity in the sense of ASTM D 7042-04 / ASTM D 4 Viscosity 40 ° C (mm ² / s) 106.08 103.79 Viscosity 100 ° C (mm ² / s) 20.66 21,074 VI 221.2 230.6 Density 40 ° C (g / cm ³ ) 1.0442 .9877 Density 100 ° C (g / cm ³ ) 0.9971 .9334 Density 15 ° C (g / cm ³ ) 1.0599 1.0058 translucent. Viscosity (mPa-s) 50mm Cone, plate, shear rate 300 sec ^-1 iA DIN 51810 231 196

Table 2 shows little influence on the rheological properties by the nanoparticles. So there are also highly concentrated dispersions, such as Levasil, possible as a nanoparticle source.

Example 6

To study the influence of the nanoparticles on friction and wear, dilution with base oil produces a nanoparticle dispersion containing 1% SiO ₂ . <u> Table 3 </ u> reference example Example 6 polyglycol, Polyglycol + 1% SiO ₂ butylfunktionalisiert, particle diameter about 60 nm viscosity Stabinger iA ASTM D 7042-04 / ASTM D 4 Stabinger Viscosity 40 ° C 237.0 240.8 Viscosity 100 ° C 43.4 45.0 VI 240.1 245.0 Density 40 ° C 1,040 1,046 Density 100 ° C 0.996 1,000 Density 20 ° C 1,055 1,061 Rheometer Anton Paar Apparently dyn. Viscosity (mPa-s) 482 493 Swing Friction Testing 50N / 30s inlet, ball / disc; lapped; 130N; 2.2mm; RT; 24Hz; 40μl, 60 min SRV, iA DIN 51834 Inlet friction coefficient min 0.131 0.131 Inlet friction coefficient max 1,137 1,139 Friction coefficient min 0.12 0.12 Friction coefficient max 0,125 0,124 wear factor 46 80 curve Description smooth curve friction at 0.12 smooth curve with friction coefficient 0.13 Four-ball apparatus long-term wear VKA continuous wear iAa DIN 51350 T3, 800 N, room temperature, 1 h Calotte Diameter (mm) 0.73 0.99 Vierkugelapparat welding force iAa DIN 51350 T2 Gutkraft (N) 1400 1800 Welding force (N) 1600 2000 Calotte Diameter (mm) 3 1.2

The nanoparticles in Example 6 have a small, negligible influence on the rheological properties, resulting in VKA endurance a slight deterioration. In the SRV, the wear factor is increased slightly, the coefficient of friction remains the same. In the welding force, a slight improvement is observed.

The effect on friction and wear is therefore dependent on the experimental conditions and can also lead to deterioration. There is no effect as an anti-wear additive.

Example 7

Effect of modified nanoparticles in a polyglycol-based gear oil formulation

Gear oil formulations were made with 60 nm SiO ₂ particles with a butyl surface modification. For this purpose, a 10% dispersion of the modified nanoparticles in polyglycol was used, which can be easily stirred into the formulation. The concentration of nanoparticles in the final formulation is 1%. The formulation was prepared in two viscosity layers (100 and 220 cst). <u> Table 4 </ u> Reference 220 cst Nanoparticulate-containing formulation, 220 cst Referenzbeisp. 100 cst Nanoparticle-containing formulation 100 cst water-miscible polyglycol monomer ethylene oxide / propylene oxide 94.15 84,15 94.15 84,15 Antioxidantsemisch 3 3 3 3 Antiwear additive 2.3 2.3 2.3 2.3 Anticorrosion additives, 0,305 0,305 0,305 0,305 Antifoam, silicone base 0.2 0.2 0.2 0.2 10% dispersion of butyl-functionalized SiO 2 nanoparticles in polyglycol particle size about 60 nm 10 10

The above-described compositions have now been used to investigate how the use of nanoparticles has an effect on the gray-patch bearing capacity. <u> Table 5 </ u> Referenzbeisp. 220 cst Nanoparticulate-containing formulation, 220 cst Reference Example 100 cst Nanoparticle-containing formulation 100 cst Viscosity viscosity and density data V 40 ° C (mm ² / sec) 236.7 238.7 98, 3 106.5 V 100 ° C 41.3 41.7 19.4 19.9 (mm ² / sec) VI 230.0 230.5 220.4 211.1 Density 40 ° C (g / ml) 1,042 1,046 1,026 1,032 FZG gray-spot short test 2200rpm. T = 90 ° C Weight change pinion / wheel total 23 7 23 12 Gray patch area after damage level 7 (mean 3 flanks 15.70% 2.50% 10% 2.90% Gray spot area after damage level 9 (mean 3 flanks 20% 4.50% 13.80% 5.20% Profile deviation after damage level 7 (average 3 flanks) 3.3 μm 0 μm 1.8 μm 5.3 μm Profile deviation after damage level 9 (mean 3 flanks) 3.3 μm 0 μm 0 mm 5 μm SKS GFKT <KS 9 Pitting is hardly to be expected SKS GFKT <KS 9 Pitting is hardly to be expected SKS GFKT <KS 9 Pitting is hardly to be expected SKS GFKT <KS 9 Pitting is hardly to be expected

As can be seen from Table 5, the gray speckling is significantly reduced when nanoparticles are used in a polyglycol gear oil. Overall, it can be stated that the use of the two compositions containing the nanoparticles was once again significantly improved by the nanoparticles when they were present as a deposit on the surfaces of the drive elements starting from a good level of references 100 cst and 220 cst) are.

Claims (7)

1. The use of a composition comprising

   (a) 0.1 to 40% by weight of surface-modified nanoparticles selected from the group consisting of silicon dioxide, zinc oxide and aluminum oxide, wherein the surface modification is brought about by means of surface-modifying reagents selected from alkyl-, aryl- and alkylarylsilanes having at least 1 to 3 of these alkyl, aryl and alkylaryl groups which may additionally contain functional groups, especially thio groups, phosphate groups, and which are used individually or in combination, and wherein the additional functional groups can react with metal surfaces and

   (b) 99.9 to 60% by weight a carrier material selected from the group consisting of synthetic and native ester oils, polyglycols, synthetic hydrocarbon oils

   wherein the composition is applied to the surfaces of drive elements for prevention or reduction of fatigue damage, trench formation or micropitting.
2. The use of a composition as claimed in claim 1, wherein the composition comprises mixtures of nanoparticles having both different substances and different particle sizes.
3. The use of a composition as claimed in any of claims 1 to 2, wherein the surface-modified nanoparticles have a particle size of 10 nm to less than 200 nm, wherein the particle size is determined by dynamic light scattering in dispersion.
4. The use of a composition as claimed in any of claims 1 to 3, wherein the composition is introduced into a lubricant selected from the group of the
5. The use of a composition as claimed in claim 4, wherein the lubricant is selected from the group consisting of a lubricant oil or mixtures of lubricant oils, polyglycols, silicone oils, perfluoropolyethers, mineral oils, ester oils, hydrocarbon oils, phenyl ether oils, native oils, derivatives of native oils, an organic or inorganic thickener, especially PTFE, graphite, metal oxides, boron nitride, molybdenum disulfide, phosphates, silicates, sulfonates, polyimides, metal soaps, metal complex soaps, ureas and mixtures thereof, solid lubricants such as graphite, MoS₂.
6. The use of a composition as claimed in either of claims 4 and 5, wherein the following are additionally present in the composition: soluble additives, especially aromatic amines, phenols, phosphates, sulfur carriers and anticorrosives, antioxidants, antiwear agents, friction reducers, agents for protection against metal influences, UV stabilizers.
7. The use of a composition as claimed in any of claims 1 to 3, present in a lubricant, based on the final formulation, in an amount of 0.1 to 10% nanoparticles, 99.9 to 90% lubricant.

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