Methods for producing metal-coated carbon material and carbon-metal composite material using the same

Abstract

Methods for producing a transition-metal-coated carbon material having a transition metal coating which has a high adhesion strength between the transition metal and the carbon material, and which is neither exfoliated nor detached in subsequent processing are provided. The transition-metal-coated carbon material may be obtained by adhering a compound containing transition metal ions onto a surface of a carbon material and by reducing the transition metal ions with carbon in the carbon material by a heat treatment, thereby to form elemental transition metal. Here, the transition metal is Fe, Co, Ni, Mn, Cu or Zn. Moreover, also provided is a carbon-metal composite material exhibiting an excellent mechanical strength and thermal conductivity, by improving affinity with a metal such as aluminium by use of the transition-metal-coated carbon material.

1 . A transition-metal-coated carbon material produced by: (1) adhering a compound onto a surface of a carbon material, the compound containing transition metal ions in a first oxidation state; and (2) reducing the transition metal ions with carbon in the carbon material by a heat treatment in any one of a vacuum and an inert atmosphere, thereby to form any one of elemental transition metal and transition metal ions in a second oxidation state, wherein the second oxidation state is a lower oxidation state than the first oxidation state, the transition metal is selected from the group consisting of Fe, Co, Ni, Mn, and Zn, and the carbon material is selected from the group consisting of pitch-based carbon fibers having a length of 500 nm to 30 mm, and polyacrylonitrile-based carbon fibers having a length of 500 nm to 30 mm. 
     
     
         2 . The transition-metal coated carbon material according to  claim 1 , wherein the heat treatment in step (2) is carried out at a temperature of 1000 to 1500° C. 
     
     
         3 . The transition-metal coated carbon material according to  claim 1 , wherein, in step (2), carbon in the carbon material is consumed, and small pores are formed in a surface of the carbon material, and the thermally reduced elemental transition metal or transition metal ions in the second oxidation state are formed in the form of particulates adhered in the small pores. 
     
     
         4 . A carbon-metal composite material obtained by integrating the transition-metal-coated carbon material according to  claim 1  with a matrix metal, wherein a content of carbon in the carbon-metal composite material is 10 to 80% by volume, and wherein the matrix metal is selected from the group consisting of aluminum, copper, magnesium, and alloys based on the metals. 
     
     
         5 . The carbon-metal composite material according to  claim 4 , wherein the integration is achieved by a pulse electric current sintering method. 
     
     
         6 . The carbon-metal composite material according to  claim 4 , wherein major axes of the carbon material are oriented at angles within ±30° with respect to a specific plane, and projection lines of the major axes are randomly oriented in the specific plane. 
     
     
         7 . The carbon-metal composite material according to  claim 4 , wherein major axes of the carbon material are oriented at angles within ±30° with respect to a direction of a specific axis. 
     
     
         8 . The carbon-metal composite material according to  claim 7 , wherein the integrating step including applying a magnetic field to a mixture of the transition-metal-coated carbon material and the matrix metal, the carbon material has a major axis and a minor axis, and has an aspect ratio of from 10 to 5000, and the major axes of the carbon material are oriented at angles within ±30° with respect to a direction of an axis of applying the magnetic field.