Learn about high thermal conductivity carbon materials

      Previous metal (aluminum, copper) heat sinks are difficult to meet the needs of heat dissipation due to the problems of high density, high thermal expansion coefficient, and impure materials. With the rapid development of science and technology, aerospace, satellite communications, high-speed computers and other fields are paying more and more attention to heat dissipation issues, and higher requirements for thermal management materials are put forward.    

      Because of its low density, high strength, high thermal conductivity, and chemical resistance, carbon materials are expected to replace the previous metal materials and become a new generation of high thermal conductivity materials.

      The heat conduction of carbon materials is mainly realized by the thermal vibration of lattice atoms. The type of carbon fiber, matrix type, density, specific heat capacity, graphitization degree, preform structure, fiber volume fraction, heat treatment temperature/graphitization temperature, etc. affect carbon materials The main factor of thermal conductivity.  

      At present, there are mainly three types of high thermal conductivity carbon materials:

      1. Diamond material    

      At present, it is known that natural diamond has the highest thermal conductivity among natural materials, and its room temperature thermal conductivity is about 2000 to 2100W/(m∙K). At the same time, diamond is also a good insulator and an ideal substrate heat dissipation material. At present, the diamond carbon film prepared by chemical vapor deposition method has the advantages of high quality and low cost.    

      2. Graphite material    

      Graphite is composed of six prism faces and two close-packed base faces. It belongs to the hexagonal structure and is mainly divided into two categories: natural graphite and artificial graphite. The thermal conductivity of ordinary graphite at room temperature is only 70 to 150W/(m∙K), while the thermal conductivity of natural graphite on the 002 crystal plane at room temperature can reach 2200W/(m∙K). The thermal conductivity on the surface has also reached 2000W/(m∙K).    

      3. Graphene materials    

      The graphene material is composed of a two-dimensional planar structure composed of a single layer of carbon atoms closely arranged in a regular hexagon. It is a honeycomb shape and is a single layer of carbon atom surface material exfoliated from graphite. Micromechanical exfoliation method, epitaxial growth method, chemical vapor deposition method and graphene oxide chemical reduction method are the main preparation methods of graphene. The room temperature thermal conductivity of single-layer suspended graphene can reach 3000 to 5300W/(m∙K) ).

       Carbon atoms have a special arrangement. Commonly used carbon materials have a huge structure and anisotropy of thermal conductivity, that is, they have high thermal conductivity in the direction of the graphite crystal planes, while the thermal conductivity between the crystal planes is very small. The preferred orientation limits its thermal conductivity in the thickness direction.    

       However, the advantages of carbon materials cannot be ignored. The thermal management materials that make use of their checks and balances are especially suitable for dissipating heat from components with large heat fluxes in small spaces, and can meet the development requirements of next-generation electronic components, and are of great significance to the development of modern industry, national defense and high technology.