Carbon nanoparticle-containing nanofluid

• US 7,871,533 B1
• Filed: 07/28/2006
• Issued: 01/18/2011
• Est. Priority Date: 01/12/2006
• Status: Active Grant

• Current Assignee: South Dakota School of Mines and Technology
• Original Assignee: South Dakota School of Mines and Technology
• Inventors: Haiping, Hong, Waynick, John Andrew
• Primary Examiner(s): Kopec; Mark
• Assistant Examiner(s): Nguyen; Khanh Tuan
• Application Number:
  US11/494,954
• Publication Number:
  US 20110003721A1
• Time in Patent Office: 1,635 Days
• Field of Search: 252/71, 252/502, 252/511, 252/70, 252/73, 252/74, 252/402, 165/8.4, 165/80.4, 424/46, 428/408, 428/901, 423/447.1, 508/128, 508/345, 508/413, 977/742, 977/750, 977/752, 977/773, 977/902
• US Class Current: 252/70
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C09K 5/10 Liquid materials
• CPC Class Codes: C10M 169/04 Mixtures of base-materials and additives
• CPC Class Codes: C10M 177/00 Special methods of preparation of lubricating compositions; Chemical modification by after-treatment of components or of the whole of a lubricating composition, not covered by other classes
• CPC Class Codes: C10M 2201/041 Carbon; Graphite; Carbon black
• CPC Class Codes: C10M 2205/0285 used as base material
• CPC Class Codes: C10M 2207/2835 used as base material
• CPC Class Codes: C10M 2219/044 Sulfonic acids, Derivatives thereof, e.g. neutral salts
• CPC Class Codes: C10N 2020/06 Particles of special shape or size
• CPC Class Codes: C10N 2030/00 Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
• CPC Class Codes: C10N 2050/10 Semi-solids; greasy
• CPC Class Codes: C10N 2070/00 Specific manufacturing methods for lubricant compositions
• CPC Class Codes: Y10S 977/742 Carbon nanotubes, CNTs
• CPC Class Codes: Y10S 977/75 Single-walled
• CPC Class Codes: Y10S 977/752 Multi-walled
• CPC Class Codes: Y10S 977/773 Nanoparticle, i.e. structure having three dimensions of 100 nm or less
• CPC Class Codes: Y10S 977/902 Specified use of nanostructure

Abstract

The present invention relates to compositions of a nanofluid, which comprises a thermal transfer fluid and carbon nanoparticles. The nanofluid may be hydrophilic nanofluids, such as a coolant, or hydrophobic nanofluids, such as nanolubricants or nanogreases. In particular, the present invention provides a homogenous hydrophilic nanofluid, which contains soluble carbon nanotubes in the hydrophilic thermal transfer fluid. The present invention also provides a nanogrease, which is a sustainable dispersion of solid carbon nanotubes in a hydrophobic thermal transfer fluid. The solid carbon nanotubes function as both as a thickener to modulate viscosity and as a solid heat transfer medium to enhance thermal conductivity and high temperature resistance.

Claims

1. A stable nanofluid comprising a hydrophobic thermal transfer fluid and carbon nanotubes dispersed in the thermal transfer fluid, wherein the carbon nanotubes have not been chemically modified or functionalized, wherein the nanofluid is free of a surfactant and has a shear stability based on the amount of change in penetration, as determined by D 1403, ¼

scale, between the worked 60 strokes value and the worked 100,000 strokes value is no greater than 10%.

2. The nanofluid of claim 1, wherein the carbon nanotubes have a solubility of no less than 0.01% in the hydrophobic thermal transfer fluid.

3. The nanofluid of claim 1 further comprising one or more chemical additives.

4. The nanofluid of claim 1, wherein the hydrophobic thermal transfer fluid is selected from the group consisting of petroleum distillates, synthetic petroleum oils, greases, gels, oil-soluble polymer composition, vegetable oils, and combinations thereof.

5. The nanofluid of claim 1, wherein the hydrophobic thermal transfer fluid has a viscosity of from about 2 to about 800 centistokes.

6. The nanofluid of claim 1, wherein the hydrophobic thermal transfer fluid is a synthetic petroleum oil.

7. The nanofluid of claim 6, wherein the synthetic petroleum oil is selected from the group consisting of polyalphaolefins, polyol esters, and combinations thereof.

8. The nanofluid of claim 7, wherein the polyol ester is pentaerythritol ester, trimethylolpropane ester, or neopentyl glycol ester.

9. The nanofluid of claim 7, wherein the synthetic petroleum oil is a polyalphaolefin or mixture thereof.

10. The nanofluid of claim 1, wherein the amount by weight of the carbon nanotubes is no greater than about 30%.

11. The nanofluid of claim 10, wherein the amount of carbon nanotubes is no greater than about 15% by weight.

12. The nanofluid of claim 1, wherein the carbon nanotube is a single-walled carbon nanotube (SWNT).

13. The nanofluid of claim 1, wherein the carbon nanotube is a multi-walled carbon nanotube (MWNT).

14. The nanofluid of claim 1, wherein the hydrophobic thermal transfer fluid is a grease.

15. The nanofluid of claim 1, wherein the amount of hydrophobic thermal transfer fluid is about 70 to about 98% by weight.

16. The nanofluid of claim 1, wherein the oil separation as determined by FTM 321.3 (cone leakage procedure), is less than 6% by weight for 24 hours at 100°

C. and at 177°

C.

17. The nanofluid of claim 1, wherein the copper corrosion as determined by ASTM D4808 for 24 hours at 100°

C. and at 177°

C. is no more tarnished than a 1B.

18. A stable nanogrease comprising a hydrophobic thermal transfer fluid and carbon nanotubes dispersed in the thermal transfer fluid, wherein the carbon nanotubes have not been chemically modified or functionalized, wherein the nanogrease is free of a surfactant and has a shear stability based on the amount of change in penetration, as determined by D 1403, ¼

scale, between the worked 60 strokes value and the worked 100,000 strokes value is no greater than 10%.

19. The nanogrease of claim 18, wherein the carbon nanotube is a single-walled carbon nanotube.

20. The nanogrease of claim 18, wherein the carbon nanotube is a multi-walled carbon nanotube.

21. The nanogrease of claim 18, wherein the amount of carbon nanotubes is no greater than about 30% by weight.

22. The nanogrease of claim 18, wherein the hydrophobic thermal transfer fluid is selected from mineral oils, synthetic petroleum oils, diesters, polyalphaolefins, polyol esters, polyglycols, and combinations thereof.

23. The nanogrease of claim 22, wherein the hydrophobic thermal transfer fluid is a mineral oil, or combinations thereof.

24. The nanogrease of claim 22, wherein the hydrophobic thermal transfer fluid is a diester, or combinations thereof.

25. The nanogrease of claim 22, wherein the hydrophobic thermal transfer fluid is a polyglycol, or combinations thereof.

26. The nanogrease of claim 18, wherein the hydrophobic thermal transfer fluid is a synthetic petroleum oil, or combinations thereof.

27. The nanogrease of claim 26, wherein the synthetic petroleum oil is selected from the group consisting of alkylaryls, silicones, polyalphaolefins, polyol esters, and combinations thereof.

28. The nanogrease of claim 27, wherein the synthetic petroleum oil is selected from the group consisting of polyalphaolefins, polyol esters, and combinations thereof.

29. The nanogrease of claim 28, wherein the polyol ester is pentaerythritol ester, trimethylolpropane ester, or neopentyl glycol ester.

30. The nanogrease of claim 27, wherein the synthetic petroleum oil is a polyalphaolefin, or combinations thereof.

31. The nanogrease of claim 27, wherein the synthetic petroleum oil is a polyol ester, or combinations thereof.

32. The nanogrease of claim 18, wherein the amount of hydrophobic thermal transfer fluid is about 70 to about 98% by weight.

33. The nanogrease of claim 18, wherein the amount of carbon nanotubes is no greater than 15% by weight.

34. The nanogrease of claim 18, wherein the hydrophobic thermal transfer fluid is a polyalphaolefin and combinations thereof, and the carbon nanotubes are single walled nanotubes.

35. The nanogrease of claim 34, wherein the amount of carbon nanotubes is no greater than 15% by weight.

36. The nanogrease of claim 18, wherein the oil separation as determined by FTM 321.3 (cone leakage procedure), is less than 6% by weight for 24 hours at 100°

C. and at 177°

C.

37. The nanogrease of claim 18, wherein the copper corrosion as determined by ASTM D4808 for 24 hours at 100°

C. and at 177°

C. is no more tarnished than a 1B.