Advantages of carbon materials in thermal conductivity and heat dissipation

In the current electronics and optoelectronics industries, as electronic devices and their products develop towards high integration and high computing, the dissipated power has doubled. Heat dissipation has gradually become a key factor restricting the sustainable development of the electronics industry. Finding heat management materials with excellent thermal conductivity is crucial for the next generation of integrated circuits and three-dimensional electronic product designs.

The thermal conductivity of traditional ceramic materials (such as boron nitride, aluminum nitride) and metal materials (such as copper, aluminum) is only a few hundred W/(m·K) at most. In comparison, the thermal conductivity of carbon materials such as diamond, graphite, graphene, carbon nanotubes, and carbon fiber is even more amazing. For example, graphite has a theoretical thermal conductivity of up to 4180W/mk in the direction parallel to the crystal layer, which is almost 10 times that of traditional metal materials such as copper, silver, and aluminum. In addition, carbon materials also have excellent properties such as low density, low thermal expansion coefficient, and good high-temperature mechanical properties.

Graphene

Graphene is a single-layer carbon atom surface material peeled off from graphite. It has a honeycomb-shaped two-dimensional plane structure composed of single-layer carbon atoms tightly arranged in regular hexagons. The structure is very stable. The connection between carbon atoms inside graphene is very flexible. When external force is applied to graphene, the carbon atom surface will bend and deform, so that the carbon atoms do not have to rearrange to adapt to the external force, thereby maintaining structural stability. This stable lattice structure gives graphene excellent thermal conductivity.

Carbon nanotubes

Since the discovery of carbon nanotubes in 1991, it has been a focus, attracting many scientists to study the thermal conductivity of carbon nanotubes. Carbon nanotubes are made of single-layer or multi-layer graphite sheets curled up, and are divided into three types: single-walled, double-walled and multi-walled.

The special structure gives carbon nanotubes extremely high thermal conductivity. Some researchers have calculated that the thermal conductivity of single-walled carbon nanotubes at room temperature is 3980 W/(m·K), the thermal conductivity of double-walled carbon nanotubes is 3580 W/(m·K), and the thermal conductivity of multi-walled carbon nanotubes is 2860 W/(m·K).

Diamond

The crystal structure of diamond is a close arrangement of carbon atoms in tetrahedrons, and all electrons participate in bonding. Therefore, its room temperature thermal conductivity is as high as 2000~2100 W/(m·K), which is one of the materials with the best thermal conductivity in nature. This feature makes it irreplaceable in the field of high-end heat dissipation.

Carbon fiber

Carbon fiber is treated by high-temperature carbonization to form a turbostratic graphite structure. If its axial graphite lattice is highly oriented, it can achieve ultra-high thermal conductivity. For example, the thermal conductivity of mesophase pitch-based carbon fiber is 1100 W/(m·K), and the thermal conductivity of vapor-grown carbon fiber can reach 1950 W/(m·K).

Graphite

Graphite has a hexagonal crystal structure, consisting of six facets and two close-packed basal planes. The first layer of the hexagonal grid of carbon atoms is staggered by 1/2 of the hexagonal diagonal line and overlapped in parallel with the second layer. The third layer and the first layer are repeated in position, forming an ABAB… sequence. The thermal conductivity of natural graphite along the (002) crystal plane is 2200 W/(m·K), and the in-plane thermal conductivity of highly oriented pyrolytic graphite can also reach 2000 W/(m·K).

The above carbon materials all have extremely high thermal conductivity, so they have attracted much attention in the field of high heat dissipation requirements. Next, let’s look at several classic carbon-based conductive/heat dissipating materials.

Carbon materials, with their unique crystal structure and physical and chemical properties, have demonstrated irreplaceable advantages in the field of thermal conductivity and heat dissipation. With the advancement of preparation technology and the expansion of application scenarios, carbon-based materials such as graphene and diamond are expected to promote heat dissipation solutions in industries such as electronics and aerospace to a higher level.