CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based on, and claims priority from the prior Japanese Patent Application No. 2019-057635, filed on Mar. 26, 2019, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The disclosure relates to a metal-plated carbon material and a manufacturing method thereof.

BACKGROUND

In recent years, reduction in weight of transportation equipment such as automobiles and airplanes has been demanded to improve fuel efficiency. In view of this, the use of carbon fiber reinforced plastic (CFRP) for bodies of the transportation equipment has been studied. However, CFRP has lower conductivity than steel plates. For this reason, in a case where CFRP is used for the bodies of the transportation equipment, the following problems are concerned: grounding cannot be taken; and an electromagnetic wave shielding effect is reduced.

Regarding those problems, plating a carbon material such as carbon fibers with a highly conductive metal such as copper has been studied. Such a related art is disclosed in JP 2007-186823 A and JP 2008-208456 A.

Specifically, J P 2007-186823 A discloses a carbon fiber surface treatment method in which a surface of a carbon fiber is treated with an alkaline degreasing solution to make the surface of the carbon fiber hydrophilic. According to the surface treatment method disclosed in JP 2007-186823 A, a plating solution permeates the inside of the carbon fiber, and therefore it is possible to cause the carbon fiber to uniformly carry a large amount of metal by electroplating.

JP 2008-208456 A discloses a method of manufacturing a metal-plated carbon material, in which a carbon fiber material is immersed in a supercritical fluid or subcritical fluid containing an organometallic complex, and the organometallic complex is reduced and activated, and then electroless plating is performed. According to the method of manufacturing a metal-plated carbon material disclosed in JP 2008-208456 A, a uniform metal film is formed.

SUMMARY

However, the surface treatment method disclosed in JP 2007-186823 A is problematic in that mechanical characteristics of the carbon fiber, such as tensile strength, may be reduced due to alkali treatment. Further, the method of manufacturing a metal-plated carbon material disclosed in JP 2008-208456 A needs a reduction or activation step after adhesion of the organometallic complex. This increases the number of steps, which is problematic. Furthermore, in the method of manufacturing a metal-plated carbon material disclosed in JP 2008-208456 A, in a case where the complex is decomposed and reduced by simple heat treatment, a ligand contained in the complex is decomposed, whereas a metal element is not easily reduced or activated. This decreases plating efficiency, which is problematic. In the method of manufacturing a metal-plated carbon material disclosed in JP 2008-208456 A, in a case where heat treatment is performed in the presence of a gaseous reducing agent such as hydrogen gas, the metal element can be reduced or activated. In this case, however, an increase in costs is problematic.

The disclosure has been made in view of the above problems. An object of the disclosure is to provide a metal-plated carbon material and a manufacturing method thereof, by which a metal-plated carbon material having high mechanical characteristics and high plating efficiency can be manufactured with a small number of steps.

A metal-plated carbon material according to an aspect of the disclosure includes: a carbon material; and a metal layer covering a surface of the carbon material, in which, in the metal layer, crystal grains forming the metal layer have an average crystal grain size of 110 nm or less.

In the above metal-plated carbon material, the metal layer is preferably made from one or more metals selected from the group consisting of palladium, copper, nickel, cobalt, gold, silver, and platinum.

A method of manufacturing a metal-plated carbon material according to another aspect of the disclosure, includes: a metal complex fixation step of immersing a carbon material in a supercritical fluid or subcritical fluid containing an organometallic complex of a first metal to form a metal-complex-fixed carbon material in which the organometallic complex is fixed to a surface of the carbon material; and a first energization deposition step of energizing the metal-complex-fixed carbon material in an electroless plating solution containing a second metal to decompose the organometallic complex of the first metal and deposit the second metal on the surface of the carbon material.

The method of manufacturing a metal-plated carbon material, preferably includes: a metal complex fixation step of immersing a carbon material in a supercritical fluid or subcritical fluid containing an organometallic complex of a first metal to form a metal-complex-fixed carbon material in which the organometallic complex is fixed to a surface of the carbon material; and a second energization deposition step of energizing the metal-complex-fixed carbon material in a conductive aqueous solution having conductivity of 100 μS/cm or more to decompose the organometallic complex of the first metal and deposit the first metal on the surface of the carbon material.

In the method of manufacturing a metal-plated carbon material, the first metal is preferably made from one or more metals selected from the group consisting of palladium, copper, nickel, cobalt, gold, silver, and platinum.

In the method of manufacturing a metal-plated carbon material, the second metal is preferably made from one or more metals selected from the group consisting of palladium, copper, nickel, cobalt, gold, silver, and platinum.

In the method of manufacturing a metal-plated carbon material, current density of energization in the energization deposition step is preferably 0.01 A/cm2or less.

According to the metal-plated carbon material and the manufacturing method thereof according to the present embodiment, it is possible to provide a metal-plated carbon material and a manufacturing method thereof, by which a metal-plated carbon material having high mechanical characteristics and high plating efficiency can be manufactured with a small number of steps.

