Composite materials with high Z-direction electrical conductivity

1. A method of fabricating a composite structure, comprising:

(a) forming a plurality of prepreg plies, each prepreg ply comprising a fiber layer of reinforcement carbon fibers embedded in a curable matrix resin, and conductive nano-sized particles dispersed throughout the matrix resin;

(b) laying up the prepreg plies together with at least one nonwoven uncoated carbon veil in a stacking arrangement such that at least one nonwoven carbon veil is positioned between two adjacent prepreg plies, forming a laminate;

(c) consolidating the laminate with application of pressure; and

(d) curing the laminate;

wherein each of the conductive nano-sized particles has at least one dimension smaller than 100 nm, and

wherein the nonwoven carbon veil is comprised of randomly arranged uncoated carbon fibers and has an areal weight of about 1 gsm to about 10 gsm.

2. The method of claim 1 , wherein

each prepreg ply at (a) further comprises polymeric particles positioned adjacent to at least one side of the layer of reinforcement carbon fibers, and

after consolidating at (c), at least some polymeric particles penetrate through the nonwoven carbon veil.

3. The method of claim 2 , wherein the polymeric particles are insoluble thermoplastic or elastomeric particles, and said insoluble particles remain as discreet particles after curing of the laminate.

4. The method of claim 1 , wherein the conductive nano-sized particles are carbon-based, nano-sized structures selected from the group consisting of: carbon nano-tubes (CNTs), carbon nano-fibers, carbon nano-ropes, carbon nano-ribbons, carbon nano-fibrils, carbon nano-needles, carbon nano-sheets, carbon nano-rods, carbon nano-cones, carbon nano-scrolls, carbon nano-ohms, carbon black particles, graphite nano-platelets, graphite nano-dots, graphenes, and combination thereof.

5. The method of claim 4 , wherein the carbon-based, nano-sized structures are carbon nanotubes (CNTs).

6. A method of fabricating a composite material comprising:

(a) forming a least one curable resin film comprising conductive nano-sized particles dispersed therein;

(b) combining the at least one curable resin film with at least one nonwoven uncoated carbon veil and a fiber layer of reinforcement carbon fibers such that the nonwoven carbon veil is positioned between the resin film and the fiber layer;

(c) applying heat and pressure to the curable resin film, the nonwoven carbon veil and the fiber layer to form a prepreg ply with resin-impregnated carbon fibers and resin-impregnated carbon veil,

wherein the conductive nano-sized particles have at least one dimension smaller than 100 nm and are the only conductive material in the curable resin film at (a), and

wherein the nonwoven uncoated carbon veil is comprised of randomly arranged uncoated carbon fibers and has an areal weight of about 1 gsm to about 10 gsm.

7. The method of claim 6 , wherein

the at least one curable resin film at (a) further comprises polymeric particles, and

after applying heat and pressure at (e), at least some polymeric particles penetrate through the nonwoven carbon veil.

8. The method of claim 6 , wherein two curable resin films are formed at (a), and two nonwoven uncoated carbon veils are combined with the two resin films and the fiber layer at (c) such that the fiber layer is positioned between the two nonwoven carbon veils and each resin film is in contact with one of the nonwoven carbon veils.

9. The method of claim 6 , wherein the conductive nano-sized particles are carbon-based, nano-sized structures selected from the group consisting of: carbon nano-tubes (CNTs), carbon nano-fibers, carbon nano-ropes, carbon nano-ribbons, carbon nano-fibrils, carbon nano-needles, carbon nano-sheets, carbon nano-rods, carbon nano-cones, carbon nano-scrolls, carbon nano-ohms, carbon black particles, graphite nano-platelets, graphite nano-dots, graphenes, and combination thereof.