EP3794162B1 - Lubricants with in-situ formation of dlc layers - Google Patents

Description

The present invention relates to the use of novel lubricants for the formation of in-situ Diamond-Like-Carbon (DLC) layers. In particular, the invention relates to a lubricant in the form of an oil or grease based on hydrocarbons, which contains non-ferrous metal particles and at the same time a non-ferrous metal deactivator.

The development of new lubricants must go hand in hand with the general advancement of technology, which places new and higher demands on the lubricant compositions. In various areas of vehicle technology and industry, the demands placed on lubricants are increasing, in particular to reduce friction and wear. Fewer and fewer lubricants are to be used in order to reduce costs. This means that lubricants are becoming more and more efficient and at the same time resources are to be conserved.

It was therefore proposed to provide moving parts in vehicle technology with DLC layers, whereby wear and tear and friction can be minimized and the vehicle parts are therefore more powerful and have fewer emissions close. The DLC layers are usually produced in a vacuum by depositing the carbon layers using chemical (CVD) or physical (PVD) vapor phase deposition processes. For example, describes the U.S. 9,951,291 B2 to provide the surface of a tribological system with a nanocomposite layer consisting of MoNx or VN ₂ and copper by plasma treatment. Hydrocarbon-based lubricants react under tribological stress on this layer to form a DLC coating, which is attributed to the catalytic effect of the copper. A disadvantage of this method, however, is that it is difficult to apply the layers under comparable conditions that are required for applying a DLC layer. Furthermore, the copper contained in the layer can have negative effects on the lubricant at the points that are not exposed to the tribological load, such as increasing the viscosity or the lubricant becoming sludgy or pasty. The WO 2016/065175 A1 describes the use of a lubricant composition for the in-situ formation of a diamond-like carbon (DLC) layer on a surface of a component in roller bearings and gears. This lubricating composition contains an oil, synfluid poly-alpha-olefin 4 (PAO4), and an additive, 5% by mass cyclopropane carboxylic acid (CPCa).

The object of the present invention was therefore to provide a lubricant for the formation of in-situ Diamond-Like-Carbon (DLC) layers that meets the above requirements, in particular causes low coefficients of friction, long service lives and reduced signs of wear on the components .

For this purpose, according to the invention, a lubricant composition consisting of an oil or grease based on hydrocarbons, non-ferrous metal nanoparticles and a non-ferrous metal deactivator as well as customary additives is provided.

This lubricant can be in the form of fats, pastes or oils. The underlying lubricating oil contains synthetic hydrocarbons such as PAOs or mPAOs, mineral oil, native oils and derivatives of native oils, esters, polyglycols, phenyl ethers, silicone oils or perfluoropolyethers. Organic or inorganic substances can be used as thickeners, in particular PTFE, graphite, metal oxides, boron nitride, molybdenum disulphide, phosphates, silicates, Sulfonates, polyimides, metal soaps, metal complex soaps, ureas and mixtures thereof, solid lubricants such as graphite or MoS ₂ .

The non-ferrous metals are selected from the group consisting of metals of the first (Sc-Zn), second (Y-Cd) and third (La-Hg) period of the transition metals, Mn, Fe, Co, Cu, Y, Re, Os being particularly preferred , particularly preferably Cu is used. Alloys of the non-ferrous metals mentioned can also be used.

The ferrous metal deactivators or inhibitors are substances that protect the metallic surface of the nanoparticles from corrosive attack, for example from oxygen with the formation of oxides, or can at least slow down this attack.

These are usually substances that can form coordinate bonds with the surface atoms of the nanoparticles. Reactive substances that form monolayers on the metal surfaces can also be used. The inhibitor is selected in such a way that the inhibitor interacts preferentially with the surface of the nanoparticle and not with the surface of the component (selective inhibitor).

These substances often have aromatic rings and heteroatoms with lone pairs of electrons that can act as donors.

Examples of heteroaromatic compounds are oxazoles, imidazoles, triazoles and triazines, which can have a wide variety of substituents. Examples of reactive substances are acids, especially carboxylic acids and hydroxycarboxylic acids, for example oleic acid.

For example, the non-ferrous metal deactivator inhibits the copper particles in the lubricant composition and protects them from aging. Under tribological stress, the copper particles release free copper surfaces and thus catalyze the polymerization or the formation of a DLC layer. When the tribological load is removed, the exposed copper surfaces are again inhibited by the excess non-ferrous metal deactivator. The copper, even in its inhibited form, has a positive influence on WEC (white etching cracks) and has a wear-protecting effect.

• 0,01 bis 10 Massen-% Buntmetalle sowie
• 0,001 bis 10 Massen-% Buntmetalldeaktivator.

The lubricant composition according to the invention contains, as described in claim 1, 99.989 to 80% by mass of a lubricant based on a fat or oil, including additives,

• 0.01 to 10% by mass of non-ferrous metals and
• 0.001 to 10% by mass of non-ferrous metal deactivator.

A lubricant composition which contains 0.01 to 5% by mass of non-ferrous metals is particularly preferred. The particle size of the non-ferrous metals ranges from 1 to 5000 nm, preferably 1 to 500 nm, particularly preferably 1 to 50 nm.

The amount of inhibitors used (based on the content of nanoparticles) can be up to the same mass fraction, preferably half the mass fraction, particularly preferably one tenth of the mass fraction compared to the nanoparticles.

Phenolic and aminic antioxidants are used as additives. Succinic acid derivatives, in particular amidized succinic acid semiesters or alkaline earth metal oxides, preferably calcium oxide and/or magnesium oxide and calcium, magnesium and/or sodium sulfonates or salts of dicarboxylic acids having 8 to 20 carbon atoms, preferably disodium sebacate, can also be used as corrosion protection additives. In addition, EP/AW additives are used, which can contain sulfur and/or phosphorus as a component.

The gear oils can also contain standard gear oil packages as well as polymer-based defoamers and silicone-containing and silicone-free compounds.

The invention is explained in more detail on the basis of the following examples.

example 1

Lubricating oil for medium-load gears, e.g. for the automotive sector

• 99,989 Massen-% bis 98,9 Massen-% Schmieröl bestehend aus
  89,85 bis 66,70 Massen-% eines PAO-Gemisches der Viskosität 68 bis 680 cst bei 40°C, 10,0 Massen-% bis 30,0 Massen-% Diester der Viskosität 25 bis 100 cst bei 40°C, 0,05 Massen-% bis 3,0 Massen-% Getriebeöladditivpackage sowie 0,1 Massen-% bis 0,3 Massen-% Entschäumer,
• 0,01 Massen-% bis 1,00 Massen-% Partikel von Übergangsmetallen ausgewählt aus Cu, Mn, Fe, Co, Y, Re, Os mit Partikelgrößen von 500 bis 3000 nm und
• 0,001 Massen-% bis 0,100 Massen-% Buntmetallinhibitoren ausgewählt aus Triazolen, Oxazolen, Thiazolen, Triazinen oder Carbonsäuren verwendet.

For a lubricating oil for a medium-duty transmission

• 99.989% by mass to 98.9% by mass lubricating oil consisting of
  89.85 to 66.70% by mass of a PAO mixture with a viscosity of 68 to 680 cst at 40°C, 10.0% by mass to 30.0% by mass of diester with a viscosity of 25 to 100 cst at 40°C, 0.05% by mass to 3.0% by mass gear oil additive package and 0.1% by mass to 0.3% by mass defoamer,
• 0.01% by mass to 1.00% by mass of particles of transition metals selected from Cu, Mn, Fe, Co, Y, Re, Os with particle sizes of 500 to 3000 nm and
• 0.001% by mass to 0.100% by mass of non-ferrous metal inhibitors selected from triazoles, oxazoles, thiazoles, triazines or carboxylic acids.

example 2

Lubricating oil for heavily loaded gears, e.g. for open drives in mills or rotary kilns as well as for industrial gears

• 98,91 Massen-% bis 87,1 Massen-% Schmieröl bestehend aus
  89,85 bis 66,70 Massen-% eines PAO-Gemisches der Viskosität 68 bis 680 cst bei 40°C, 10,0 Massen-% bis 30,0 Massen-% Diester der Viskosität 25 bis 100 cst bei 40°C, 0,05 Massen-% bis 3,0 Massen-% Getriebeöladditivpackage sowie 0,1 Massen-% bis 0,3 Massen-% Entschäumer,
• 1,0 Massen-% bis 10,0 Massen-% Partikel von Übergangsmetallen ausgewählt aus Cu, Mn, Fe, Co, Y, Re, Os mit Partikelgrößen von 500 bis 3000 nm und 0,09 Massen-% bis 2,9 Massen-% Buntmetallinhibitoren ausgewählt aus Triazolen, Oxazolen, Thiazolen, Triazinen oder Carbonsäuren verwendet.

For a lubricating oil for a highly loaded transmission

• 98.91% by mass to 87.1% by mass lubricating oil consisting of
  89.85 to 66.70% by mass of a PAO mixture with a viscosity of 68 to 680 cst at 40°C, 10.0% by mass to 30.0% by mass of diester with a viscosity of 25 to 100 cst at 40°C, 0.05% by mass to 3.0% by mass gear oil additive package and 0.1% by mass to 0.3% by mass defoamer,
• 1.0% by mass to 10.0% by mass of particles of transition metals selected from Cu, Mn, Fe, Co, Y, Re, Os with particle sizes of 500 to 3000 nm and 0.09% by mass to 2.9% by mass of non-ferrous metal inhibitors selected from triazoles, oxazoles, thiazoles, triazines or carboxylic acids.

Example 3

Long-term lubricating grease with a wide range of applications for roller and plain bearings

• 99,989 Massen-% - 98,9 Massen-% Schmierfett bestehend aus
  86,8 - 73,0 Massen-% PAO der Viskosität 45 cst, 12,0 bis 20,0 Massen-% eines Verdickungsmittels ausgewählt aus der Klasse von Lithium-Komplexseifen, 1,0 bis 4,0 Massen-% aminischer und phenolischer Antioxidantien sowie 0,2 bis 3,0 Massen-% EP/AW-Additive auf Basis S/P-Chemie,
• 0,01 Massen-% bis 1,00 Massen-% Partikel von Übergangsmetallen ausgewählt aus Cu, Mn, Fe, Co, Y, Re, Os mit Partikelgrößen von 500 bis 3000 nm und
• 0,001 Massen-% bis 0,100 Massen-% Buntmetallinhibitoren ausgewählt aus Triazolen, Oxazolen, Thiazolen, Triazinen oder Carbonsäuren enthalten.

In a long-lasting grease that can be used in a wide range of applications

• 99.989% by mass - 98.9% by mass lubricating grease consisting of
  86.8-73.0% by mass of PAO with a viscosity of 45 cst, 12.0 to 20.0% by mass of a thickener selected from the class of lithium complex soaps, 1.0 to 4.0% by mass of aminic and phenolic Antioxidants and 0.2 to 3.0% by mass of EP/AW additives based on S/P chemistry,
• 0.01% by mass to 1.00% by mass of particles of transition metals selected from Cu, Mn, Fe, Co, Y, Re, Os with particle sizes of 500 to 3000 nm and
• 0.001% by mass to 0.100% by mass of non-ferrous metal inhibitors selected from triazoles, oxazoles, thiazoles, triazines or carboxylic acids.

example 4

Long-term lubricating grease with excellent wear protection

• 98,91 Massen-% bis 87,1 Massen-% Schmierfett bestehend aus
  86,8 bis 73,0 Massen-% PAO der Viskosität 45 cst, 12,0 bis 20,0 Massen-% eines Verdickungsmittels ausgewählt aus der Klasse von Lithium-Komplexseifen, 1,0 bis 4,0 Massen-% aminischer und phenolischer Antioxidantien sowie 0,2 bis 3,0 Massen-% EP/AW-Additive auf Basis S/P-Chemie,
• 1,0 Massen-% bis 10,0 Massen-% Partikel von Übergangsmetallen ausgewählt aus Cu, Mn, Fe, Co, Y, Re, Os mit Partikelgrößen von 500 bis 3000 nm und 0,09 Massen-% bis 2,9 Massen-% Buntmetallinhibitoren ausgewählt aus Triazolen, Oxazolen, Thiazolen, Triazinen oder Carbonsäuren.

A lubricating grease with a long-term effect and an excellent anti-wear effect consists of

• 98.91% by mass to 87.1% by mass of lubricating grease consisting of
  86.8 to 73.0% by mass of PAO with a viscosity of 45 cst, 12.0 to 20.0% by mass of a thickener selected from the class of lithium complex soaps, 1.0 to 4.0% by mass of aminic and phenolic Antioxidants and 0.2 to 3.0% by mass of EP/AW additives based on S/P chemistry,
• 1.0% by mass to 10.0% by mass of particles of transition metals selected from Cu, Mn, Fe, Co, Y, Re, Os with particle sizes from 500 to 3000 nm and 0.09% by mass to 2.9% by mass -% non-ferrous metal inhibitors selected from triazoles, oxazoles, thiazoles, triazines or carboxylic acids.

Example 5

Roller bearing grease with high wear protection

• 99,989 Massen-% bis 98,9 Massen-% Schmierfett bestehend aus
  92,8 bis 80,0 Massen-% PAO der Viskosität 45 cst, 6,0 bis 10,0 Massen-% eines Verdickungsmittels ausgewählt aus der Klasse von Lithium-Einfachseifen, 1,0 bis 4,0 Massen-% aminischer und phenolischer Antioxidantien sowie 0,2 bis 6,0 Massen-% EP/AW-Additive auf Basis S/P-Chemie,
• 0,01 Massen-% bis 1,00 Massen-% Partikel von Übergangsmetallen ausgewählt aus Cu, Mn, Fe, Co, Y, Re, Os mit Partikelgrößen von 500 bis 3000 nm und
• 0,001 Massen-% bis 0,100 Massen-% Buntmetallinhibitoren ausgewählt aus Triazolen, Oxazolen, Thiazolen, Triazinen oder Carbonsäuren.

Contains a roller bearing grease with a high anti-wear effect

• 99.989% by mass to 98.9% by mass of lubricating grease consisting of
  92.8 to 80.0% by mass of PAO of viscosity 45 cst, 6.0 to 10.0% by mass of a thickener selected from the class of lithium simple soaps, 1.0 to 4.0% by mass of aminic and phenolic Antioxidants and 0.2 to 6.0% by mass of EP/AW additives based on S/P chemistry,
• 0.01% by mass to 1.00% by mass of particles of transition metals selected from Cu, Mn, Fe, Co, Y, Re, Os with particle sizes of 500 to 3000 nm and
• 0.001% by mass to 0.100% by mass of non-ferrous metal inhibitors selected from triazoles, oxazoles, thiazoles, triazines or carboxylic acids.

Claims (6)

1. Use of a lubricant composition containing

   99.989 to 87.1% w/w lubricant in the form of a fat or oil, including additives,

   0.01 to 10% w/w non-ferrous metal particles, selected form the group consisting of metals of the first (Sc - Zn), second (Y - Cd) and third (La - Hg) period of transition metals, as well as their alloys, and

   0.001 to 2.9% w/w non-ferrous metal deactivator selected from the group consisting of heteroaromatic compounds, such as oxazoles, imidazoles, triazoles and/or triazines or acids, particularly carboxylic acids and hydroxycarboxylic acids, in particular oleic acids,

   to form a diamond-like carbon (DLC) layer in-situ on a surface of a component in antifriction bearings, sliding bearings and gear mechanisms.
2. The use of a lubricant composition according to claim 1, to form a diamond-like carbon (DLC) layer in-situ on a surface of a component in the automotive sector in-situ.
3. The use of a lubricant composition according to claim 1 or 2, wherein the oil of the lubricant is selected, as individual component or in mixtures, from the group consisting of synthetic hydrocarbons, such as PAOs or mPAOs, mineral oil, native oils and derivatives of native oils, esters, polyglycols, phenyl ethers, silicone oils or perfluoropolyethers.
4. The use of a lubricant composition according to one of the preceding claims, wherein the lubricant is selected, with a thickener in pure form or in mixtures, from the group consisting of organic or inorganic substances, in particular PTFE, graphite, metal oxides, boron nitride, molybdenum disulphide, phosphates, silicates, sulphonates, polyimides, metal soaps, metal complex soaps, urea and mixtures thereof, solid lubricants such as graphite or MoS₂, and thickened to form a fat.
5. The use of a lubricant composition according to claim 1, wherein the non-ferrous metal nanoparticles are selected from Mn, Fe, Co, Cu Y, Re and Os.
6. The use of a lubricant composition according to claim 5, wherein the particle size of the non-ferrous metals ranges from 500 to 3000 nm.