High strength and high modulus carbon fibers

Abstract

A carbon fiber has a fiber tensile strength in a range of 5.5 GPa to 5.83 GPa. The carbon fiber has a fiber tensile modulus in a range of 350 GPa to 375 GPa. The carbon fiber also has an effective diameter in a range of 5.1 μm to 5.2 μm. In a method of making a carbon fiber, PAN (poly(acrylonitrile-co methacrylic acid)) is dissolved into a solvent to form a PAN solution. The PAN solution is extruded through a spinneret, thereby generating at least one precursor fiber. The precursor fiber is passed through a cold gelation medium, thereby causing the precursor fiber to gel. The precursor fiber is drawn to a predetermined draw ratio. The precursor fiber is continuously stabilized to form a stabilized fiber. The stabilized fiber is continuously carbonized thereby generating the carbon fiber. The carbon fiber is wound onto a spool.

What is claimed is: 
     
         1 . A carbon fiber characterized as having a fiber tensile strength in a range of 5.5 GPa to 5.83 GPa, a fiber tensile modulus in a range of 350 GPa to 375 GPa, and an effective diameter in a range of 5.1 μm to 5.2 μm. 
     
     
         2 . The carbon fiber of  claim 1  having an oxidative thermal degradation temperature of at least 815° C. 
     
     
         3 . The carbon fiber of  claim 1  arranged in a tow of no more than 100 carbon fibers. 
     
     
         4 . A tow, comprising a plurality of carbon fibers that have an average fiber tensile strength in a range of 5.5 GPa to 5.83 GPa, an average fiber tensile modulus in a range of 350 GPa to 375 GPa, and an average effective diameter in a range of 5.1 μm to 5.2 μm. 
     
     
         5 . The tow of  claim 4 , wherein the carbon fibers have an average oxidative thermal degradation temperature of at least 815° C. 
     
     
         6 . The tow of  claim 4 , wherein the plurality of carbon fibers includes about 100 carbon fibers. 
     
     
         7 . The tow of  claim 4 , wherein the plurality of carbon fibers are without any surface treatment and are without any sizing. 
     
     
         8 . A method of making a carbon fiber, comprising the steps of:
 (a) dissolving PAN (poly(acrylonitrile-co methacrylic acid)) into a solvent to form a PAN solution;   (b) extruding the PAN solution through a spinneret, thereby generating at least one precursor fiber;   (c) passing the precursor fiber through a cold gelation medium, thereby causing the precursor fiber to gel;   (d) drawing the precursor fiber to a predetermined draw ratio;   (e) continuously stabilizing the precursor fiber to form a stabilized fiber;   (f) continuously carbonizing the stabilized fiber thereby generating the carbon fiber; and   (g) winding the carbon fiber onto a spool.   
     
     
         9 . A carbon fiber made according to the method recited in  claim 8 . 
     
     
         10 . The method of  claim 8 , wherein the carbon fiber is made without any surface treatment and without any sizing. 
     
     
         11 . The method of  claim 8 , wherein the gelation medium comprises methanol. 
     
     
         12 . The method of  claim 8 , wherein the gelation medium has a temperature of about −50° C. 
     
     
         13 . The method of  claim 8 , wherein there is an air gap of about 2 cm between the spinneret and the top surface of the gelation medium. 
     
     
         14 . The method of  claim 8 , wherein stabilizing step comprises passing the precursor fiber through a plurality of stabilization zones, including a first stabilization zone that heats the precursor fiber to a temperature of about 180° C. and a last stabilization zone that heats the precursor fiber to a temperature of about 250° C. 
     
     
         15 . The method of  claim 14 , wherein the plurality of stabilization zones includes: a first stabilization zone that heats the fiber to about 180° C.; a second stabilization zone that heats the precursor fiber to about 190° C.; a third stabilization zone that heats the precursor fiber to about 200° C.; a fourth stabilization zone that heats the fiber to about 210° C.; a fifth stabilization zone that heats the precursor fiber to about 230° C.; and a sixth stabilization zone that heats the precursor fiber to about 250° C. 
     
     
         16 . The method of  claim 8 , wherein carbonizing step comprises passing the precursor fiber through a plurality of carbonization zones that heat the fiber to a temperature of about 1450° C. 
     
     
         17 . The method of  claim 16 , wherein the plurality of carbonization zones includes: a warming zone that heats the precursor fiber to about 500° C.; a first carbonization zone that heats the precursor fiber to about 600° C.; a second carbonization zone that heats the precursor fiber to about 675° C.; and a third carbonization zone that heats the precursor fiber to about 1450° C. 
     
     
         18 . The method of  claim 8 , wherein the carbon fiber has a fiber tensile strength in a range of 5.5 GPa to 5.83 GPa, a fiber tensile modulus in a range of 350 GPa to 375 GPa, and an effective diameter in a range of 5.1 μm to 5.2 μm. 
     
     
         19 . The method of  claim 8 , wherein the carbon fiber has an oxidative thermal degradation temperature of at least 815° C. 
     
     
         20 . The method of  claim 8 , further comprising the step of bundling a plurality of carbon fibers into a tow of about 100 carbon fibers.