Expandable Graphite

Expandable Graphite . It is chemically treated with high-purity graphite and incorporates several intercalation compounds. When exposed to high temperature, it expands and its volume increases sharply to form worm-like graphite. Its physical and chemical properties are unique, so it shows great strengths in many fields. The great use of expanded graphite is first in fire retardant. Because it expands in case of fire, it generates a dense thermal insulation layer, which effectively cuts off the contact between the fire source and the coating, and is widely used in flame retardant materials in construction, transportation, electronics and other industries. For example, it can be made into flame retardant panels, fire-resistant doors and windows, sealing inserts, flame retardant paints, etc., which can greatly improve safety performance. Secondly, its excellent sealing property makes it suitable for high-temperature sealing materials, such as gaskets, sealing rings, etc., which are commonly used in sealing systems of petroleum, chemical, and electric power equipment. It withstands high temperature, high pressure, and corrosion to ensure the stable operation of machinery and equipment. And its good electrical and thermal conductivity is used to prepare conductive materials, such as conductive rubber, conductive coatings, radiator substrates, and battery plates. Based on expanded graphite, graphite paper and graphite foil are prepared, which are widely used in high-tech fields such as electronic shielding, heat sinks, and fuel cells. Furthermore, expanded graphite can also adsorb organic matter and heavy metal ions for environmental treatment and wastewater purification. Its adsorption capacity is large and its efficiency is high. It is often used as an emergency material for oil leakage or a heavy metal trap in wastewater. Material modification is also helpful. Doping expanded graphite into rubber, plastics or cement can significantly improve the flame retardancy, heat resistance and mechanical properties of the product. In the fields of chemical catalysis and electrode materials, expanded graphite also plays its structural and surface area advantages, and is used for electrode materials of catalyst carriers and super capacitors. Like the above, expanded graphite serves many aspects such as fire protection, sealing, conductivity, heat dissipation, environmental protection and polymer modification with its unique properties. Technological progress, application is more extensive, and the prospect can be expected.

Expanded graphite is based on natural graphite. After specific chemical treatment, it is doped with oxidants and expansion agents such as sulfuric acid and nitric acid, so that the graphite layers react and give it the ability to expand. Every time there is a high temperature, usually between 200 degrees and 300 degrees, the gas trapped in it violently escapes, causing sharp separation between the layers, the sheet stretches, and the volume increases. Examining its expansion ratio, today based on the volume change, the expansion ratio of common expanded graphite is about 80 times to 300 times. Or with excellent craftsmanship, the expansion ratio can exceed 300. However, depending on the purity of the raw material, the particle size, the type and concentration of the impregnating agent, and the heating rate, there are also high and low points. Expanded graphite is initially flaky, and after being heated, it turns into worm-like clusters. It has black and gray color, pore hyperplasia, light and loose weight, and is resistant to high temperature and has excellent heat insulation. Its expansion ratio is directly related to its application in fire protection, sealing, adsorption and metallurgy. The higher the expansion ratio, the looser the material, and the better the filling and heat insulation properties; if the expansion is insufficient, the shape is not full and the use is limited. Today's laboratories often measure its ratio by standard methods, quantitatively place graphite in a high-temperature furnace, heat it instantly, and collect the expansion product. Measure its volume to compare it with the original volume to obtain its expansion ratio. For high-quality expanded graphite, the expansion ratio is often greater than one hundred and fifty times, and the few are not less than fifty times. However, the expansion ratio is too high, and the mechanical strength is inferior, so it must be selected according to the use. is based on the expansion ratio of expanded graphite, which is between 50 and 300 times, which is caused by the actual economic use and process conditions. To know the details, it is recommended to refer to the chemical classics and experimental data to accurately demonstrate its ability.

Expandable Graphite, graphite through a special chemical treatment, so that the interlayer embedded in acidic compounds, fire will expand like a worm, the volume increased by dozens of times. Its flame retardant mechanism, covering several ends. At the beginning of the fire, graphite is sensitive to heat, rapid heat generation, the internal salt into gas, expansion of graphite sheets, curling and staggered, into a porous expansion body. It is time to isolate oxygen and prevent the spread of fire. Its surface is a strong carbon layer, blocking the heat source, and the substrate under it is sheltered and not easy to burn. Furthermore, the expansion of graphite at the combustion interface forms a protective barrier to prevent the escape of flammable gases, or to prevent the penetration of heat. This carbon layer is dense in texture and difficult to conduct heat. Under the flame, the material does not transfer heat and is difficult to burn. And graphite expands, releasing harmless gases, does not increase harmful smoke, and the environment is safe. Expanded graphite can still be shared with other flame retardants, and the synergy effect is obvious. For example, mixed with phosphorus and nitrogen flame retardants, it can not only suppress smoke, but also improve the decomposition temperature, making the material structure firmer. And the expanded layer can withstand high temperature and is not easy to break. Due to its stable structure, excellent heat resistance and long-lasting fire resistance, it is widely used in polymers, plastics, rubber and many other fields. The rate of expanded graphite is closely related to the grade, and the particle size is suitable, so the expansion is more efficient and the barrier effect is more consistent. Most importantly, Expandable Graphite has become an excellent flame retardant material today due to thermal expansion, oxygen isolation, generation of carbonaceous barriers, and suppression of heat and gas transmission. It is not only for fire extinguishing, but also can delay the fire, protect the main material, and reduce losses. With today's advanced technology, its expansion efficiency is becoming more and more excellent, and its position in the field of flame retardancy is becoming more and more important.

Expandable Graphite which is flammable and has expansion characteristics. Storage and transportation should be especially cautious. For storage, choose a ventilated and dry place, and avoid moisture to prevent graphite from absorbing moisture and agglomerating and causing character variation. The container should be sealed and should not be in direct contact with air. In case of high temperature or flame, it is easy to cause spontaneous expansion and combustion, so the storage temperature must be constant and not too high. During handling, it should be handled with care to avoid severe vibration and friction, which will cause damage to its surface. Do not mix with flammable, strong oxidants, and acids to avoid chemical reactions. Packaging materials should be flame retardant and firm to prevent them from spilling and losing. The outside of the container must be clearly marked, indicating that it is expanded graphite, warning that the fire source is far away to prevent accidental contact. The means of transportation should be well ventilated to prevent high temperature exposure to the sun, and the loading should be strictly layered up and down, and away from the open flame of the heat source. During the transportation process, rain-proof facilities must be made to strictly prevent moisture, because it is easy to exacerbate its spontaneous expansion after moisture. It should not be packaged and transported with food and feed to avoid cross-contamination. In the event of damage and leakage, it is advisable to use clean non-spark equipment to collect the residual material and dispose of it centrally. Operators should wear protective equipment such as labor protection gloves and masks to prevent inhalation of dust and harm to body and mind. Emergency treatment should also prepare fire extinguishing equipment, such as dry powder, sand, etc. In case of fire, it is not suitable to spray with water. Due to the intense chemical reaction that is easy to support combustion, it is better to use dry chemical fire extinguishing agent. For long-term storage, it is advisable to regularly inspect the warehouse to prevent insects and rats from biting and packaging, and timely remediation of hidden dangers. In short, the storage and transportation of expanded graphite is essential to prevent moisture and fire, separate foreign objects, ventilate and seal, and identify clearly. Operation must follow the norms to be foolproof.

For expanded graphite, graphite is treated by chemical or physical methods, so that a certain substance is inserted between the layers, which can expand rapidly when heated, surge in volume, and have unique properties. It is widely used in metallurgy, sealing, fire protection and many other fields. Its commodity circulation must be determined according to the use and convenience of the packaging method. Because graphite expanded powder is delicate, easy to absorb moisture, and has high flammability, transportation and storage need to be cautious, so the packaging form is also similar. Common packaging includes woven bags, paper drums, composite bags, and ton bags. Woven bags are interwoven with polypropylene silk and covered with plastic film, which is strong and moisture-proof. They are often packaged in small packages of fifty kilograms and twenty-five kilograms. The weaving method is light and tough, suitable for short-distance circulation, but the moisture-proof performance is slightly inferior. For paper barrels, thick cardboard is supplemented by a metal ring bundle mouth, and the outer cover is sealed with a sealing film. The capacity is mostly 25 to 50 kilograms. Each barrel is airtight, waterproof and dustproof, and suitable for export transportation of high-quality expanded graphite. Composite bags are made of plastic and aluminum foil, which are both soft and sealed, corrosion-resistant, and water vapor-proof. They are especially suitable for shipping by sea. Tonne bags, also known as flexible container bags, have a capacity of up to 500 kilograms or even one ton per bag. They are used for large-scale shipments. They are lifted and unloaded by lifting tools. They are simple and efficient. They are often used for the entry and exit of bulk raw materials in factories. In addition to packaging, there are also lined plastic bags to isolate moisture, and sometimes double-layer packages to enhance the protective function. Labels indicate specifications, batch numbers, net weight and the name of the manufacturer for easy verification and circulation. Or seal and add tray, it is especially convenient to open the box for acceptance. It should be protected from exposure to sun, rain and violent collision during transportation to ensure that its properties remain unchanged. To sum up, expanded graphite packaging is divided according to its quality characteristics and uses, but safety, sealing, moisture-proof and dust-proof are the first priorities. Circulation in the world, smooth trade, and packaging are the key.