Expandable graphite was first discovered by German Schauufautl. In 1841, Schauufautl soaked natural graphite in a mixture of concentrated HNO3 and concentrated H2SO4, took it out and dried it a few hours later, and found that the graphite had expanded.

The United Carbide Company of the United States first applied for a patent for expandable graphite manufacturing technology in 1963 and carried out industrial production in 1968

Application:

1.Sealing material The raw material high-carbon graphite is mixed with concentrated sulfuric acid and concentrated nitric acid for acidification treatment, heat treatment and then compression molding. The prepared flexible graphite is a new type of high-performance sealing material and an in-situ growth nanomaterial. Compared with traditional sealing materials such as asbestos rubber, it has excellent properties such as good compressibility, resilience, self-adhesion, and low density, and can be used for a long time under harsh conditions such as high temperature and high corrosion. The graphite sheets and sealing components made of it are widely used in aerospace, machinery, electronics, nuclear energy, petrochemical, electric power, shipbuilding, smelting and other industries. Because it has excellent characteristics such as light weight, electrical conductivity, thermal conductivity, high temperature resistance, acid and alkali corrosion resistance, good resilience, lubricity, plasticity and chemical stability, it is known as the "king of seals" in the world.

2. The field of environmental protection The expandable graphite obtained by high temperature expansion has rich pore structure, so it has excellent adsorption performance, so it has a wide range of uses in environmental protection and biomedicine. The pore structure of expandable graphite has two kinds of open pores and closed pores, and the pore volume accounts for about 98%. Because it is dominated by macropores and mesopores, it is also different in adsorption characteristics from microporous materials such as activated carbon. It is suitable for liquid phase adsorption but not for gas phase adsorption. It is lipophilic and hydrophobic in liquid phase adsorption. 1 g of expandable graphite can adsorb more than 80 g of heavy oil, so it is a promising environmentally friendly material for removing oil pollution from water surfaces. In the wastewater treatment of chemical enterprises, microorganisms (bacteria) are often used for treatment. Expandable graphite is a good microbial carrier, especially in the treatment of water contaminated by oily organic macromolecules. Regeneration and reuse, so it has a good application prospect.

3. Medicine Because expandable graphite has adsorption properties for organic and biological macromolecules, it has a wide range of application prospects in biomedical materials.

4. High-energy battery material Expandable graphite is used as a battery material to convert the free energy change of the interlayer reaction of expandable graphite into electrical energy. Usually expandable graphite is used as the cathode, lithium is used as the anode, or expandable graphite composite silver oxide is used as the cathode, and zinc is used as the anode. Expandable graphites of fluorinated graphite, graphitic acid, and metal halides such as AuCl3 and TiF4 have been used in batteries.

5. Flame retardant and fireproof

Fireproof sealing strip Due to the expandability of expandable graphite and its high temperature resistance, expandable graphite has become an excellent sealing material and is widely used in fireproof sealing strips. There are two main forms: the first is to mix, vulcanize, and shape expandable graphite materials with rubber materials, inorganic flame retardants, accelerators, vulcanizing agents, reinforcing agents, fillers, etc. to make various specifications of expansion. Sealing strip, mainly used in fire doors, fire glass windows and other occasions. This inflatable sealing strip can block the flow of smoke from beginning to end in normal temperature and fire. The other is to use glass fiber tape as a carrier, and bond the expandable graphite to the carrier with a certain adhesive. The shear resistance provided by the carbide formed by this adhesive at high temperature can effectively prevent the graphite slide. It is mainly used for fire doors, but it cannot effectively block the flow of cold smoke at normal or low temperature, so it must be used in conjunction with normal temperature sealants.
Flame retardant of plastic materials Expandable graphite is a good flame retardant for plastic materials. It has the characteristics of non-toxicity and no pollution. It can achieve ideal flame retardant effect when used alone or mixed with other flame retardants. When expandable graphite achieves the same flame retardant effect, the dosage is much smaller than that of ordinary flame retardants. Its principle of action is: at high temperature, the expandable graphite expands rapidly, suffocating the flame, and at the same time, the generated graphite expanded material covers the surface of the substrate, which isolates the contact between heat radiation and oxygen; the acid radicals inside the interlayer expand when they expand. The release also promotes the carbonization of the substrate, so as to achieve good results through a variety of flame retardant methods.

Fireproof bag, plastic fireproof plugging material, and fireproof ring can be used as fireproof bag, plastic fireproof plugging material and fireproof ring because of the anti-destructive ability of expandable graphite at high temperature and its high expansion rate. Intumescent flame retardant materials, used for fire blocking in buildings (for example: sealing building pipes, cables, wires, gas, gas pipes, holes through which air pipes pass, etc.).

Application on coatings Fine particles of expandable graphite can be added to ordinary coatings to produce flame-retardant and anti-static coatings with better effect, which can improve its high temperature resistance and fire resistance. A large number of lightweight non-combustible carbon layers formed in the fire can effectively block the radiation of heat to the substrate and effectively protect the substrate. In addition, because graphite is a good electrical conductor, the prepared coating can prevent the accumulation of electrostatic charges, and is used in petroleum storage tanks to achieve the dual effect of fire prevention and anti-static.

Fireproof board, fireproof paper Corrosion and high temperature resistant board: The metal base layer is lined with an expandable graphite layer, there is a carbonized adhesive layer between the expandable graphite layer and the metal base layer, and the expandable graphite layer is covered with a carbonized protective layer. With anti-corrosion, high temperature and high pressure performance. At the same time, it is resistant to thermal shock and can be used normally at low temperatures. It is not afraid of rapid cooling and rapid heating, and has excellent thermal conductivity. The operating temperature is - 100 ~ 2000 ℃. Wide application range, easy manufacture and low cost. In addition, graphite paper made by expanding expandable graphite at high temperature is also used in places where fire and heat preservation are required.