Expandable Graphite
Size
0.50mm or 0.106mm, etc
Package
25 kg small bags into ton bags
Origin
China
Features
Preservative/Electrical and thermal conductivity, etc.
Application
Fireproof sealing element, flame retardant, refractory brick, etc.
Expandable graphite crystal is a typical layered carbon material. Other heterogeneous particles such as atoms, molecules, ions, and even atomic clusters are inserted into the interlayer of crystalline graphite by physical or chemical methods to form a new layered compound, which is called graphite interlayer compound, namely expandable graphite.
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Expandable graphite, also known as flexible graphite, has super pressure resistance, high-temperature resistance, low-temperature resistance, corrosion resistance, radiation resistance, flexibility, and plasticity. At the same time, expandable graphite also has certain earthquake resistance and superconductivity. It is non-toxic and harmless, and there is little smoke when burning, which also lays a foundation for expandable graphite as a flame retardant and refractory.
There are also many methods to prepare expandable graphite, but the most important are four, one is the chemical intercalation method, one is an electrochemical method, one is the ultrasonic oxidation method, and the other is the gas-phase diffusion method. Various preparation methods have their advantages and disadvantages. For example, the expandable graphite prepared by the electrochemical method has low sulfur content, The expandable graphite prepared by ultrasonic oxidation accelerates the anodic oxidation speed and shortens the oxidation time. The gas-phase diffusion law can control the number of layers of expandable graphite, but the production cost is very high. Therefore, each of us should prepare expandable graphite according to actual needs.
Due to its good performance, expandable graphite is usually used for sealing materials, environmental protection, high-energy battery materials, and flame retardants. Expandable graphite can be used as a sealing material because, compared with traditional sealing materials such as rubber, expandable graphite has the advantages of good compressibility, good resilience, and low density. It can also be used for a long time in a high temperature and highly corrosive environment. Therefore, it is known as the king of sealing and is also widely used in aerospace machinery, electronics, nuclear energy, and other industries.
In addition, due to the expandability and high-temperature resistance of expandable graphite, the fireproof sealing strip makes expandable graphite an excellent sealing material and is widely used in fireproof sealing strips. The flame-retardant expandable graphite of plastic materials is a good flame-retardant for plastic materials. It has the characteristics of non-toxic and non-polluting. It can be used alone or mixed with other flame retardants to achieve the desired flame retardant effect.
In addition to these uses, people are still studying the follow-up development direction of expandable graphite, and can also have a deeper understanding of expandable graphite
The development directions of expandable graphite are as follows：
1. Expandable graphite special purposes
The results show that the graphite worm has the function of absorbing electromagnetic waves, which makes the expandable graphite have a high military application value. Both the American army and China army have carried out experimental research in this field. The following requirements must be met: (1) the initial expansion temperature is low and the expansion volume is large（ 2) The chemical properties are stable, and the expansion ratio is not attenuated for 5 years（ 3) The surface of expandable graphite is neutral and has no corrosion to shell.
2. Granular expandable graphite
Small particle expandable graphite mainly refers to 300 expandable graphite, its expansion volume is 100ml/g, the product is mainly used for flame retardant coating, and its demand is large.
3. Expandable graphite with high initial expansion temperature
The initial expansion temperature of expandable graphite with high initial expansion temperature is 290-300 ℃, and the expansion volume is ≥ 230ml / g. This kind of expandable graphite is mainly used as a flame retardant for engineering plastics and rubber. The product has been developed by Hebei Agricultural University and has applied for a national patent.
4. Surface modified graphite
When expandable graphite is used as flame retardant material, it involves the problem of solubility between graphite and other components. Because of the high mineralization degree of graphite surface, it is neither oil-friendly nor hydrophilic. Therefore, the surface of graphite must be modified to solve the problem of the solubility of graphite and other components. It has been proposed that the surface of graphite will be white, that is, to cover the graphite surface with a solid white film. This is a difficult problem to solve. It involves the problems of membrane chemistry or surface chemistry. The laboratory may do it and there are problems in industrialization. This kind of white expandable graphite is mainly used as a flame retardant coating.
5. Low initial expansion temperature and low-temperature expansion graphite
The temperature of the expansion of such expandable graphite is 80-150 ℃, and the expansion volume reaches 250ml / g at 600 ℃. The difficulty of preparing expandable graphite satisfying this condition lies in: (1) choosing the appropriate intercalator（ 2) Control and control of drying conditions（ 3) Determination of water content（ 4) Solution to environmental protection problems. At present, the preparation of low-temperature expandable graphite is still in the experimental stage.
The residual sulfur in the early preparation of expandable graphite products will corrode the metal, and it is easy to be oxidized under the condition of high temperature and the presence of an oxidant, which reduces the sealing effect. Another problem of the industrial products of expandable graphite is that the initial expansion temperature is very high, usually as high as 600 ℃ to have a higher expansion volume, generally at 900 ℃ expansion volume can reach 250 ml / g. In the fields of multi-band smoke agent, intumescent flame retardant, and fire extinguishing agent, it is hoped that the lower the expansion temperature of expandable graphite, the better; For other applications, low expansion temperature is also beneficial to reduce the energy consumption, expansion equipment, and process conditions. Therefore, low-temperature expandable graphite with excellent expansion performance at low temperature is a new development direction of expandable graphite. In the past 20 years, it has focused on the improvement of graphite expansion ratio, the reduction of sulfur content, and the reduction of energy consumption and cost in the process.
The future direction of expandable graphite shows that there are more possibilities for its application. There will be more and more applications of expandable graphite in future life. This also requires continuous exploration by scientists, and each of us also To seize the opportunity, spot market opportunities for expandable graphite, grasp the first-hand dynamics and let customers buy expandable graphite at the right price and good quality.
