Magneto-carbonization method for production of carbon fiber, and high performance carbon fibers made thereby
Method for the preparation of carbon fiber from fiber precursor, wherein the fiber precursor is subjected to a magnetic field of at least 3 Tesla during a carbonization process. The carbonization process is generally conducted at a temperature of at least 400° C. and less than 2200° C., wherein, in particular embodiments, the carbonization process includes a low temperature carbonization step conducted at a temperature of at least or above 400° C. or 500° C. and less than or up to 1000° C., 1100° C., or 1200° C., followed by a high temperature carbonization step conducted at a temperature of at least or above 1200° C. In particular embodiments, particularly in the case of a polyacrylonitrile (PAN) fiber precursor, the resulting carbon fiber may possess a minimum tensile strength of at least 600 ksi, a tensile modulus of at least 30 Msi, and an ultimate elongation of at least 1.5%.
1. A method for producing a carbon fiber, the method comprising subjecting a carbon fiber precursor to a magnetic field of at least 3 Tesla with said magnetic field periodically alternating at a frequency of 1−20,000 Hz during a carbonization process, wherein said carbonization process is conducted at a temperature of at least 400° C. and less than 2200° C. to form said carbon fiber, wherein the produced carbon fiber is substantially resilient and substantially defect-free.
2. The method of claim 1 , wherein said carbonization process comprises a low temperature carbonization step conducted at a temperature of at least 400° C. and less than 1200° C., followed by a high temperature carbonization step conducted at a temperature above 1200° C.
3. The method of claim 2 , wherein said low temperature carbonization step is conducted at a temperature of at least 500° C. and less than 1200° C.
4. The method of claim 3 , wherein said high temperature carbonization step is conducted at a temperature of at least 1400° C.
5. The method of claim 3 , wherein said high temperature carbonization step is conducted at a temperature of at least 1500° C.
6. The method of claim 3 , wherein said high temperature carbonization step is conducted at a temperature of at least 1800° C.
7. The method of claim 3 , wherein said said high temperature carbonization step is conducted at a temperature of at least 2000° C.
8. The method of claim 2 , wherein said carbon fiber precursor is subjected to said magnetic field of at least 3 Tesla during the low temperature carbonization step and not during the high temperature carbonization step.
9. The method of claim 2 , wherein said carbon fiber precursor is subjected to said magnetic field of at least 3 Tesla during the high temperature carbonization step and not during the low temperature carbonization step.
10. The method of claim 2 , wherein said carbon fiber precursor is subjected to said magnetic field of at least 3 Tesla during both the low temperature carbonization step and the high temperature carbonization step.
11. The method of claim 1 , wherein said carbon fiber precursor has a composition comprised of polyacrylonitrile, polyolefin, lignin, viscose, rayon, or pitch.
12. The method of claim 1 , wherein said carbon fiber is a carbon fiber tow.
13. The method of claim 1 , wherein said carbon fiber is in a non-tow form selected from stapled or chopped fiber, yarn, fabric, mesh, or felt.
14. The method of claim 1 , wherein said carbon fiber precursor has a composition comprised of polyacrylonitrile and said carbon fiber is produced in a tow form that possesses a minimum tensile strength of at least 600 ksi, a tensile modulus of at least 30 Msi, and an ultimate elongation of at least 1.5%.
15. The method of claim 1 , wherein said carbon fiber is subsequently graphitized at a temperature of at least 2,200° C. and up to 3,200° C.
16. The method of claim 15 , wherein said graphitization is conducted in the presence of a magnetic field of at least 3 Tesla.
17. The method of claim 1 , wherein, prior to said carbonization process, said carbon fiber precursor is subjected to a stabilization process that renders the carbon fiber precursor infusible.
18. The method of claim 17 , wherein said stabilization process is conducted in the absence of a magnetic field.
19. The method of claim 17 , wherein said stabilization process is conducted in the presence of a magnetic field of at least 3 Tesla.
20. The method of claim 1 , wherein said method further comprises subjecting the carbon fiber precursor to microwave and/or plasma processing during the carbonization process.
21. The method of claim 1 , wherein the magnetic field is periodically alternating at a frequency of 10 −10,000 Hertz.
22. The method of claim 1 , wherein said carbon fiber possesses a specific surface area of 100 −3,000 m 2 /gram.
23. The method of claim 1 , wherein said carbon fiber possesses a thermal conductivity below 10 W/m-K.
24. The method of claim 1 , wherein said carbon fiber possesses a thermal conductivity above 100 W/m-K.
25. The method of claim 1 , wherein said carbon fiber is in a fused state in a three-dimensional, interconnected mat or felt.
26. The method of claim 1 , wherein said magnetic field is at least 5 Tesla.
27. The method of claim 1 , wherein said magnetic field is at least 9 Tesla.