Articles comprising high-electrical-conductivity nanocomposite material and method for fabricating same

• US 7,959,830 B2
• Filed: 12/23/2004
• Issued: 06/14/2011
• Est. Priority Date: 12/31/2003
• Status: Expired due to Fees

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Jin, Sungho
• Primary Examiner(s): Silverman; Stanley
• Assistant Examiner(s): VIJAYAKUMAR, KALLAMBELLA M
• Application Number:
  US10/584,680
• Publication Number:
  US 20080044685A1
• Time in Patent Office: 2,364 Days
• Field of Search: 252/500, 252/62.2, 252/182.1, 428/615, 428/627, 428/655, 428/323, 428/357, 428/547, 427/212, 427/217, 75245-247, 75343-374, 205/74, 205/76
• US Class Current: 252/500
• CPC Class Codes: B22F 1/054 Nanosized particles
• CPC Class Codes: B22F 1/142 Thermal or thermo-mechanical treatment
• CPC Class Codes: B22F 1/18 Non-metallic particles coated with metal
• CPC Class Codes: B22F 2201/01 Reducing atmosphere
• CPC Class Codes: B22F 2207/03 of the metallic binder phase in cermets
• CPC Class Codes: B22F 2998/00 Supplementary information concerning processes or compositions relating to powder metallurgy
• CPC Class Codes: B22F 2998/10 Processes characterised by the sequence of their steps
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 3/02 Compacting only
• CPC Class Codes: B22F 3/10 Sintering only
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C22C 47/04 by coating, e.g. with a protective or activated covering
• CPC Class Codes: C25D 15/02 Combined electrolytic and electrophoretic processes with charged materials
• CPC Class Codes: C25D 5/48 After-treatment of electroplated surfaces
• CPC Class Codes: H01B 1/026 Alloys based on copper
• CPC Class Codes: H01L 23/3732 Diamonds
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: Y10T 428/12049 Nonmetal component
• CPC Class Codes: Y10T 428/12493 Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
• CPC Class Codes: Y10T 428/12576 : Boride, carbide or nitride component
• CPC Class Codes: Y10T 428/12771 : Transition metal-base component
• CPC Class Codes: Y10T 428/25 : Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/26 : Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
• CPC Class Codes: Y10T 428/2991 : Coated

Abstract

This invention discloses novel nanocomposite material structures which are strong, highly conductive, and fatigue-resistant. It also discloses novel fabrication techniques to obtain such structures. The new nanocomposite materials comprise a high-conductivity base metal, such as copper, incorporating high-conductivity dispersoid particles that simultaneously minimize field enhancements, maintain good thermal conductivity, and enhance mechanical strength. The use of metal nanoparticles with electrical conductivity comparable to that of the base automatically removes the regions of higher RF field and enhanced current density. Additionally, conductive nanoparticles will reduce the surface'"'"'s sensitivity to arc or sputtering damage. If the surface is sputtered away to uncover the nanoparticles, their properties will not be dramatically different from the base surface. Most importantly, the secondary electron emission coefficients of all materials in the nanocomposite are small and close to unity, whereas the previously used insulating particles can produce significant and undesirable electron multiplication.

Claims

1. An article for conducting high power electrical current comprising a high conductivity nanocomposite comprised of a base of metal or alloy and a plurality of nanoscale particles dispersed within the base wherein the nanoscale particles are incorporated in a region near a surface of the base in a concentration gradient that decreases in a direction from the surface to an interior of the base, the base having an electrical resistivity less than about 10 microhm-cm and the nanoscale particles having an electrical resistivity less than about 20 microhm-cm and an average diameter of less than 500 nanometers to strengthen the base without substantially reducing the conductivity of the composite as compared with the base.

2. The article of claim 1 wherein the nanoscale particles have an average diameter less than 100 nanometers.

3. The article of claim 1 wherein the volume fraction of the nanoscale particles in the base is in the range 0.2-20% and preferably 0.5-10%.

4. The article of claim 1 wherein the base metal or alloy has an electrical resistivity less than 6 microhm-cm and preferably less than 3 microhm-cm.

5. The article of claim 1 wherein the base comprises a metal or alloy selected from the group consisting of Cu, Au, Ag, Co, Pd, Pt, Rh, Re, Cr, Zn, Au—

Ag, and Cu—

Ni.

6. The article of claim 1 wherein the base comprises copper.

7. The article of claim 1 wherein the nanoscale particles have an electrical resistivity less than 6 microhm-cm and preferably less than 3 microhm-cm.

8. The article of claim 1 wherein the nanoscale particles comprise metal particles with a solid solubility in the base of less than 0.1 atomic %.

9. The article of claim 1 wherein the nanoscale particles comprise particles that are insoluble in the base.

10. The article of claim 1 wherein the nanoscale particles comprise intermetallic compounds.

11. The article of claim 1 wherein the nanoscale particles comprise intermetallic compounds selected from the group consisting of Mn₄Al₁₁, NiAl and TiAl₃.

12. The article of claim 1 wherein the nanoscale particles comprise metal coated particles of material selected from the group consisting of carbides, nitrides, borides, carbon, graphite and diamond.

13. The article of claim 1 wherein the nanoscale particles comprise metal coated particles of material selected from the group consisting of cerium carbide, tantalum carbide, zirconium carbide, tin carbide, silicon carbide, titanium carbide and titanium nitride.

14. The article of claim 1 wherein the nanocomposite material has a sufficient concentration of nanoscale particles to enhance its mechanical strength enhanced by at least 30% over the base.

15. The article of claim 1 wherein the nanocomposite has a sufficient concentration of nanoscale particles to enhance its resistance to thermal fatigue by at least 30% over the base.

16. The article of claim 1 wherein the nanoscale particles are incorporated selectively near a surface of the base.

17. A high power microwave component comprising the article of claim 1.

18. An electrical connector or electrical contact comprising the article of claim 1.

19. A method of making a body of a high conductivity nanocomposite comprising the steps of:

forming a nanocomposite comprising a base metal or alloy and a plurality of nanoscale particles dispersed within the base wherein the nanoscale particles are incorporated in a region near a surface of the base in a concentration gradient that decreases in a direction from the surface to an interior of the base, the base having an electrical resistivity less than about 10 microhm-cm and the nanoscale particles having an average diameter of less than about 500 nanometers and electrical resistivity less than about 20 microhm-cm; and

shaping the nanocomposite into a body.

20. The method of claim 19 wherein the nanocomposite material is formed by a co-depositing the base metal or alloy and the nanoscale particles in an electrolyte solution.

21. The method of claim 20 further comprising the step of coating the nanoscale particles with metal before forming the nanocomposite.

22. The method of claim 20 further comprising the step of annealing the nanoscale particles in an inert or reducing atmosphere before forming the nanocomposite.

23. The method of claim 20 wherein the nanocomposite material is formed by coating the nanoscale particles with the base metal or alloy, pressing the coated particles together, and sintering the pressed particles.

24. The method of claim 23 wherein the nanoscale particles are coated by electroless plating.

25. The method of claim 23 wherein the nanoscale particles are coated with at least 0.1 micrometers of the base metal or alloy and preferably at least 1 micrometer.

26. The method of claim 19 wherein the nanocomposite material is formed by mixing the dispersoid particles with particles of the base metal or alloy, pressing the mixed particles together, and sintering the pressed particles.