Graphene has a wide range of applications, and coatings are an important part of many graphene applications. With various superior properties, graphene has far-reaching application prospects in electrical conductivity, anticorrosion, flame retardancy, thermal conductivity and high strength.
Graphene has the advantages of large specific surface area, good electrical conductivity, strong chemical stability, excellent mechanical properties and thermal conductivity. Graphene has excellent performance in coatings:

Electrical properties: The carrier mobility of graphene at room temperature is about 15000cm2/(V s), which is 10 times higher than that of silicon materials, and is the material with the highest known carrier mobility, indium antimonide ( InSb) more than twice. Under some specific conditions such as low temperature, the carrier mobility of graphene can even be as high as 250000cm2/(V s);

Thermal properties: Graphene has very good thermal conductivity. The thermal conductivity of pure defect-free single-layer graphene is as high as 5300W/mK, which is the highest thermal conductivity of carbon materials so far, higher than that of single-wall carbon nanotubes (3500W/mK) and multi-wall carbon nanotubes (3000W/mK). When it is used as a carrier, the thermal conductivity can also reach 600W/mK;

Mechanical properties: Graphene is one of the strongest known materials. It also has good toughness and can be bent. The theoretical Young's modulus of graphene is 1.0TPa and its inherent tensile strength is 130GPa. The reduced graphene modified by hydrogen plasma also has very good strength, and the average modulus can reach 0.25TPa. Graphite paper composed of graphene sheets has many pores, so graphite paper is very brittle, however, functionalized graphene obtained by oxidation, and then made of functionalized graphene into graphite paper will be extremely strong and tough;

Optical properties: Graphene has very good optical properties, with an absorptivity of about 2.3% over a wide wavelength range, making it almost transparent. In the range of several layers of graphene thickness, the absorption rate increases by 2.3% for each additional layer of thickness. Large-area graphene films also have excellent optical properties, and their optical properties vary with the thickness of graphene. This is the unusual low-energy electronic structure of monolayer graphene.

Based on the excellent properties of graphene, graphene has become the focus of a new generation of coatings. The functionalized graphene with a large number of oxygen-containing groups has strong bonding force with resins and polymer materials, and is suitable as a reinforcing material or functionalized material. Graphene coatings have excellent performance in anti-corrosion, electrical conductivity, anti-static and other fields.

The main applications of graphene in the field of coatings are:

First, the application of graphene in the field of conductive coatings

The surface resistance of the electrostatic conductive paint is usually between 106 and 109, which can effectively prevent the conduction of static electricity, so it is generally used in occasions with high requirements for fire protection and explosion protection. For example, the inner and outer walls of oil storage tanks, oil pipelines, oil tankers and other oil storage and oil transportation equipment in petroleum, chemical, railway, transportation and other industries, and anti-corrosion coatings for equipment in coal mines, aviation, textiles, food and other industries generally use electrostatic conductive coatings as Anti-corrosion coatings, which can not only prevent equipment corrosion to the greatest extent, but also avoid problems such as fire accidents caused by static electricity caused by charge accumulation. Graphene has both good electrical conductivity and corrosion resistance, so it is very effective in electrostatic conductive coatings.

Second, the application of graphene in the field of high thermal conductivity and heat dissipation coatings

Graphene has a high thermal conductivity. Adding graphene to coatings can significantly improve the thermal conductivity of coatings. Therefore, graphene modification has become an important development direction of heat dissipation coatings. In addition, graphene has a large specific surface area, and the paint film contains a certain amount of graphene, which can greatly increase the heat dissipation area of ​​the paint film, help the heat dissipation on the surface and inside of the paint film, and make the internal and external temperatures tend to be consistent. Because graphene coatings have good mechanical properties, corrosion resistance and aging resistance, graphene coatings are usually used as heat dissipation coatings for components in many harsh environments.

3. Application of graphene in the field of anti-corrosion coatings

1. Water-based anti-corrosion coating

Environmental protection paint is the main direction of today's paint development. Water-based coatings have become an important development target for environmentally friendly coatings due to their low VOC. Water-based paints use water as a dispersant, and the surface tension is large, and the film-forming properties of the paint film have always been unsatisfactory. Adding graphene to water-based anti-corrosion coatings can effectively improve this.

2. Application of graphene in the field of flame retardant coatings

The two-dimensional structure of graphene monomer is dispersed in the paint film and stacked on top of each other to form a dense isolation layer, which can play the role of fire and flame retardant. If resin is added to the coating, graphene can also be cross-linked with the resin molecules, which further strengthens the isolation effect and enhances the flame retardant effect. In addition, in addition to carbon dioxide and water, the combustion products of the graphene coating will leave a continuously distributed carbon layer in place, thereby improving the flame retardant effect again. For this reason, graphene also has a good application in flame retardant coatings.

3. Epoxy zinc-rich paint

Anti-corrosion coatings have always been one of the important branches of coatings and are widely used in industrial production. In the production of the national economy, the use of a large number of metal products makes equipment anti-corrosion requirements very high, and the market demand for anti-corrosion coatings continues to rise. According to statistics, the global economic loss caused by corrosion is as high as one trillion US dollars every year, far exceeding the economic loss caused by natural disasters. Adding graphene to the existing epoxy anti-corrosion coating makes the anti-corrosion coating improve the impact resistance, adhesion, water resistance, hardness and other indicators in addition to the original performance. It is widely used in equipment anticorrosion in the fields of marine engineering, transportation, large-scale industrial equipment and municipal engineering facilities.

Fourth, the application of graphene in the field of high-strength coatings

Due to the high specific surface area of ​​graphene, it has a strong adsorption force. After adding graphene to the paint, it forms a network structure during the curing process of the paint film, which greatly enhances the adhesion between the paint film and the substrate, and the paint film is more stable and stronger. The test results show that after adding graphene, the impact resistance, friction resistance, thermal conductivity, weather resistance and corrosion resistance of the coating have been greatly improved.