Nano graphene-modified lubricant

1. A lubricant composition having improved lubricant properties, comprising:

(a) a lubricating fluid; and

(b) nano graphene platelets dispersed in said fluid, wherein said nano graphene platelets have a proportion of 0.001% to 75% by weight based on the total weight of the fluid and the graphene platelets combined.

2. The lubricant composition as recited in claim 1 , further comprising a surfactant or dispersant.

3. The lubricant composition as recited in claim 1 , wherein said nano graphene platelets have an average thickness less than 10 nm.

4. The lubricant composition as recited in claim 1 , wherein said nano graphene platelets have an average thickness less than 1 nm.

5. The lubricant composition as recited in claim 1 , wherein said nano graphene platelets comprise single-layer graphene.

6. The lubricant composition as recited in claim 1 , wherein said nano graphene platelets have a length or width less than 500 nm.

7. The lubricant composition as recited in claim 1 , wherein said nano graphene platelets comprise pristine graphene, graphene oxide, or a combination thereof.

8. A lubricant composition with an enhanced thermal conductivity, comprising:

A) an effective amount of a selected neat fluid having a selected thermal conductivity;

B) an amount of from 0.001 to 60 percent by weight of nano graphene platelets dispersed into said selected neat fluid; and

C) an effective amount of at least one dispersing agent dissolved or dispersed in said neat fluid.

9. The lubricant composition of claim 8 , wherein the neat fluid is selected from the group consisting of petroleum distillates, synthetic petroleum oils, greases, gels, oil-soluble polymer composition, vegetable oils, and combinations thereof.

10. The lubricant composition of claim 8 , wherein the neat fluid is a synthetic petroleum oil selected from the group consisting of polyalphaolefins, polyol esters, and combinations thereof.

11. The lubricant composition of claim 8 , wherein said neat fluid comprises a substance selected from the group consisting of pentaerythritol ester, trimethylolpropane ester, neopentyl glycol ester and combinations thereof.

12. The lubricant composition of claim 8 , further comprising a thickener to make a grease composition.

13. The lubricant composition as recited in claim 8 , wherein said nano graphene platelets have an average thickness less than 10 nm.

14. The lubricant composition as recited in claim 8 , wherein said nano graphene platelets have an average thickness less than 1 nm.

15. The lubricant composition as recited in claim 8 , wherein said nano graphene platelets comprise single-layer graphene.

16. The lubricant composition as recited in claim 8 , wherein the nano graphene platelets have a thermal conductivity of no less than 500 W/m K.

17. The lubricant composition as recited in claim 8 , wherein the nano graphene platelets have a thermal conductivity of no less than 1,000 W/m K.

18. The lubricant composition as recited in claim 8 , wherein the nano graphene platelets have a thermal conductivity greater than 3,000 W/m K.

19. The lubricant composition as recited in claim 8 , wherein the dispersing agent comprises an anionic surfactant.

20. The lubricant composition as recited in claim 8 , wherein the dispersing agent comprises a surfactant selected from the group consisting of a sulfonate surfactant, a sulfosuccinate, a sulfosuccinamate, dioctyl sulfosuccinate, bistridecyl sulfosuccinate, di(1,3-di-methylbutyl) sulfosuccinate, and combinations thereof.

21. The lubricant composition as recited in claim 8 , wherein the composition has a thermal conductivity greater than 1.0 W/m K.

22. The lubricant composition as recited in claim 8 , wherein the composition has a thermal conductivity greater than 10 W/m K.

23. The lubricant composition as recited in claim 8 , wherein the composition has a thermal conductivity greater than 30 W/m K.

24. The lubricant composition of claim 8 , wherein said neat fluid is selected from the group consisting of Group I (solvent refined mineral oils), Group II (hydrocracked mineral oils), Group III (severely hydrocracked hydrogenated oils), Group IV (polyalphaolefins), Group VI (esters, naphthenes, and polyalkylglycols), and combinations thereof.

25. The lubricant composition of claim 8 , wherein said neat fluid is selected from the group consisting of synthetic hydrocarbon oils, halo-substituted hydrocarbon oils, polymerized and interpolymerized olefins, polybutylenes, polypropylenes, propylene-isobutylene copolymers, chlorinated polybutylenes, poly(1-octenes), poly(1-decenes), alkylbenzenes, dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di-(2-ethylhexyl)benzenes, polyphenyls, biphenyls, terphenyls, alkylated polyphenyls, alkylated diphenyl, ethers, alkylated diphenyl sulfides, and combinations thereof.

26. The lubricant composition of claim 8 , wherein said neat fluid is selected from the group consisting of the esters of dicarboxylic acids selected from the group consisting of phtalic acid, succinic acid, alkyl succinic acids and alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, alkenyl malonic acids, with an alcohols selected from the group consisting of butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol diethylene glycol monoether, propylene glycol, dibutyl adipate, di(2-ethylhexyl) sebacate, di-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azealate, dioctyl phthalate, didecyl phthalate, dicicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethylhexanoic acid, and combinations thereof.

27. The lubricant composition of claim 8 , wherein said neat fluid is selected from the group consisting of esters made from C 5 to C 12 monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, and combinations thereof.

28. The lubricant composition of claim 8 , wherein said neat fluid is selected from the group of synthetic based oil ester additives consisting of polyolesters, diesters, di-aliphatic diesters of alkyl carboxylic acids, di-2-ethylhexylazelate, di-isodecyladipate, di-tridecyladipate, and combinations thereof.

29. The lubricant composition of claim 8 , wherein said neat fluid is selected from the water-soluble group consisting of an alcohol and its derivatives.

30. The lubricant composition of claim 8 , wherein said neat fluid is selected from the water-soluble group consisting of an ethylene glycol, a propylene glycol, a methyl alcohol, an ethyl alcohol, a propyl alcohol, an isopropyl alcohol, and combinations thereof.

31. The lubricant composition of claim 8 , wherein said dispersing agent is selected from the group consisting of an lipophilic hydrocarbon group, and a polar functional hydrophilic group consisting of the class of carboxylate, ester, amine, amide, imine, imide, hydroxyl, ether, epoxide, phosphorus, ester carboxyl, anhydride, or nitrile.

32. The lubricant composition of claim 8 , wherein said dispersing agent is an ashless dispersant selected from the group consisting of N-substituted polyisobutenyl succinimides and succinates, allkyl methacrylate-vinyl pyrrolidinone copolymers, alkyl methacrylate-dialkylaminoethyl methacrylate copolymers, alkylmethacrylate-polyethylene glycol methacrylate copolymers, and polystearamides.

33. The lubricant composition of claim 8 further comprising a carbon nanotube or a graphite nano particle.

34. A lubricant composition having improved lubricant properties, comprising a lubricating fluid and at least a single-layer graphene sheet.

35. The lubricant composition of claim 34 wherein the composition comprise a plurality of single-layer graphene sheets.