Composite material

Abstract

A composite material includes a matrix and carbon fibrous structures. The carbon fibrous structure has a three dimensional network of carbon fibers, each having an outside diameter of 15-100 nm, and has a granular part with which two or more carbon fibers are tied together such that the carbon fibers extend therefrom, and the granular part being produced in a growth process of the carbon fibers. The additive amount of the carbon fibers is in the range of 0.1 to 30% by weight of total weight of the composite material.

1 . A composite material comprising a matrix and carbon fibrous structures, 
 wherein each of the carbon fibrous structures comprises a three dimensional network of carbon fibers each having an outside diameter of 15-100 nm, wherein the carbon fibrous structure further comprises a granular part, with which two or more carbon fibers are tied together such that the carbon fibers extend therefrom, and wherein the granular part is produced in a growth process of the carbon fibers, and    wherein an amount of the carbon fibers added to the matrix is in a range of 0.1 to 30% by weight of a total weight of the composite material.    
     
     
         2 . The composite material according to  claim 1 , wherein the carbon fibrous structures have an area based circle-equivalent mean diameter of 50-100 μm.  
     
     
         3 . The composite material according to  claim 1 , wherein the carbon fibrous structures have a bulk density of 0.0001-0.05 g/cm 3    
     
     
         4 . The composite material according to  claim 1 , wherein the carbon fibrous structures have an I D /I G  ratio determined by Raman spectroscopy of not more than 0.2.  
     
     
         5 . The composite material according to  claim 1 , wherein the carbon fibrous structures have a combustion initiation temperature in air of not less than 750° C.  
     
     
         6 . The composite material according to  claim 1 , wherein a diameter of the granular part is larger than outside diameters of the carbon fibers.  
     
     
         7 . The composite material according to  claim 1 , wherein the carbon fibers are produced using at least two carbon compounds, which have different decomposition temperatures.  
     
     
         8 . The composite material according to  claim 1 , wherein the carbon fibers are produced using a carbon compound that can decompose to give intermediates having different decomposition temperatures.  
     
     
         9 . The composite material according to  claim 1 , wherein the matrix comprises an organic polymer.  
     
     
         10 . The composite material according to  claim 1 , wherein the matrix comprises an inorganic material.  
     
     
         11 . The composite material according to  claim 1 , wherein the matrix comprises a metal.  
     
     
         12 . The composite material according to  claim 1 , wherein the composite material further comprises at least one filling agent selected from the group consisting of metallic minute particles, silica, calcium carbonate, magnesium carbonate, carbon black, glass fiber and another type of carbon fibers different from the carbon fibrous structures.  
     
     
         13 . The composite material according to  claim 1 , wherein the carbon fibrous structures are synthesized by: 
 preparing a carbon fiber intermediate by chemical vapor decomposition of a carbon source in the presence of a catalyst at a temperature of 800-1300° C.; and    heating the carbon fiber intermediate at a temperature of at least 2400° C.    
     
     
         14 . The composite material according to  claim 13 , wherein the carbon fiber intermediate was heated at 800-1200° C. before the heating at the temperature of at least 2400° C.