Carbon nanotube compositions

Patent metadata

Field	Value
Publication number	US-10553326-B2
Application number	US-201515325222-A
Country	US
Kind code	B2
Filing date	Jul 10, 2015
Priority date	Jul 10, 2014
Publication date	Feb 4, 2020
Grant date	Feb 4, 2020

Abstract

Metal-carbon nanotube composites having nanotubes which are uniformly dispersed within the metal matrix of the composite, and which are unbundled or substantially unbundled, have high lengths, and which can be controllably aligned are disclosed herein. Such metal-carbon nanotube composites can show improved electrical, thermal, and mechanical properties, as compared to a pristine metal or metal alloy which does not contain nanotubes dispersed therein. Facile and scalable methods of fabricating such metal-nanocarbon composites are also disclosed.

First claim

We claim:

1. A metal-carbon composite comprising:
a plurality of conformally coated carbon nanotubes having lengths in the range of 1-1000 microns which are uniformly dispersed within a metal or metal alloy matrix;
wherein the plurality of carbon nanotubes dispersed within the metal or metal alloy matrix have a controlled alignment along the in-plane direction, cross-plane direction, or along an intermediate-plane direction;
wherein the conformal coating on the plurality of coated carbon nanotubes has a thickness between 1 and 250 nm;
wherein the conformal coating comprises a metal, carbonaceous material, or polymeric material, which increases the wettability and dispersibility of the carbon nanotubes in the metal or metal alloy forming the metal or metal alloy matrix; and
wherein the metal is selected from aluminum, chromium, zinc, tantalum, platinum, gold, tin, lead, silver, titanium, indium, copper, metal oxides thereof, and combinations thereof; and
wherein the metal-carbon composite is in an interface between a heat sink or heat spreader and a heat source and the metal-carbon composite has a thermal resistance of less than 5 mm 2 K/W.

2. The metal-carbon composite of claim 1 , wherein the conformal coating comprises the metal of claim 1 or metal oxide thereof.

3. The metal-carbon composite of claim 2 , wherein the metal oxide is selected from metal oxides of aluminum, cobalt, chromium, zinc, tantalum, platinum, gold, nickel, iron, tin, lead, silver, titanium, indium, copper, and combinations thereof.

4. The metal-carbon composite of claim 1 , wherein the carbonaceous material is selected from pyrolytic carbon, graphite, single-layered graphene, and multi-layered graphene.

5. The metal-carbon composite of claim 1 , wherein the polymeric material is selected from conjugated polymers and aromatic polymers.

6. The metal-carbon composite of claim 1 , wherein the metal or metal alloy matrix comprises a metal selected from the group consisting of aluminum, copper, cobalt, chromium, zinc, tantalum, platinum, gold, nickel, iron, tin, lead, silver, titanium, indium, and combinations thereof.

7. The metal-carbon composite of claim 1 , wherein the conformal coating material is associated to the surface of the carbon nanotubes through van der Waals bonds, π-π stacking, and/or covalent bonds.

8. The metal-carbon composite of claim 1 , further comprising a plurality of metallic particles on the surface of the conformally coated carbon nanotubes.

9. The metal-carbon composite of claim 8 , wherein the metallic particles are selected from the group consisting of palladium nanoparticles, gold nanoparticles, silver nanoparticles, titanium nanoparticles, iron nanoparticles, nickel nanoparticles, copper nanoparticles, and combinations thereof.

10. The metal-carbon composite of claim 1 , wherein the composite has an electrical conductivity which is at least about 105%, 110%, 115%, 120%, 125%, 130%, 135%, 140%, 145%, 150% higher than that of an electrical conductivity of a metal or metal alloy matrix which does not contain any dispersed carbon nanotubes.

11. The metal-carbon composite of claim 1 , wherein the composite has a thermal conductivity which is at least about 20, 30, 50, or 70% greater than that of a thermal conductivity for metal or metal alloy matrix which does not contain any dispersed carbon nanotubes.

12. The metal-carbon composite of claim 1 , wherein the composite has a coefficient of thermal expansion which is at least about 50, 40, 30, 20, or 10% of a coefficient of thermal expansion for an equivalent pristine metal or metal alloy matrix.

13. The metal-carbon composite of claim 1 , wherein the composite is in an interface between the heat sink or the heat spreader and the heat source is a chip and the composite has a thermal resistance of less than 1 mm 2 K/W.

14. The metal-carbon composite of claim 1 , wherein the composite is in the form of a sheet, plate, foil, rod, wire, strip, ingot, pellet, or chunk.

15. The metal-carbon composite of claim 1 , wherein the conformal coating has a thickness between 5 and 100 nm.

16. The metal-carbon composite of claim 1 , wherein the conformal coating has a thickness between 5 and 50 nm.

17. The metal-carbon composite of claim 1 , wherein the thermal resistance is less than 1 mm 2 K/W.

18. The metal-carbon composite of claim 1 , wherein the heat source is a personal computer, server computer, memory module, graphics chip, radar, radio-frequency (RF) device, disc drive, display, light-emitting diode (LED) displays, lighting system, automotive control unit, power-electronic, solar cell, battery, communication equipment, thermoelectric generator, or imaging equipment.

19. A method of making the metal-carbon composite of claim 1 , the method comprising the steps of:
1) preparing a carbon nanotube array on a substrate, wherein the carbon nanotube array comprises a plurality of carbon nanotubes;
2) conformally coating the plurality of carbon nanotubes on the substrate with one or more coating materials in an amount effective to increase the wettability and dispersibility of the plurality of carbon nanotubes in a metal or metal alloy matrix; wherein the conformal coating on the plurality of carbon nanotubes has a thickness between 1 and 250 nm; the one or more coating materials comprise a metal, carbonaceous material, or polymeric material; and the metal is selected from aluminum, chromium, zinc, tantalum, platinum, gold, tin, lead, silver, titanium, indium, copper, metal oxides thereof, and combinations thereof;
3) adding the conformally coated carbon nanotubes on the substrate to a melt of a metal or metal alloy matrix to form a mixture; and
4) cooling the mixture in order to form a metal-carbon nanotube composite wherein the plurality of the carbon nanotubes are uniformly dispersed within the metal or metal alloy matrix; and wherein the plurality of carbon nanotubes dispersed within the metal or metal alloy matrix have a controlled alignment along the in-plane direction, cross-plane direction, or along an intermediate-plane direction; and
wherein the metal-carbon composite, when present at the interface between a heat sink or heat spreader and a heat source, the metal-carbon composite has a thermal resistance of less than 5 mm 2 K/W.

20. The method of claim 19 , wherein the substrate is a foil comprising a metal or metal alloy.

21. The method of claim 19 , wherein the carbon nanotube array is formed on one or both sides of the substrate.

22. The method of claim 19 , wherein the melt of metal or metal alloy matrix comprises a metal selected from the group consisting of aluminum, copper, cobalt, chromium, zinc, tantalum, platinum, gold, nickel, iron, tin, lead, silver, titanium, indium, and combinations thereof.

23. The method of claim 19 , wherein the substrate is formed of a metal which is different from the metal used to form the metal or metal alloy matrix melt.

24. The method of claim 19 , wherein the substrate melts at a higher temperature than the temperature of the melt of the metal or metal alloy melt in order to keep the substrate intact and the array of carbon nanotubes in their original orientation after the melt of the metal or metal alloy matrix infiltrates the array.

25. The method of claim 19 , further comprising a step of mechanical mixing or agitation of the mixture in order to control or improve the uniformity of the carbon nanotubes dispersed throughout the com

Assignees

• Georgia Tech Res Inst

Inventors

• Cola Baratunde
• Spence Daron

Classifications

• H01B1/04

  mainly consisting of carbon-silicon compounds, carbon or silicon · CPC title

• Y10S977/742

  Carbon nanotubes, CNTs · CPC title

• Y10S977/784

  Electrically conducting, semi-conducting, or semi-insulating host material · CPC title

• C01B2202/24

  Thermal properties · CPC title

• C01B32/168

  After-treatment · CPC title