Shandong Shuangyu Carbon Co., Ltd. Specializing in the production of expanded graphite, high-purity graphite, flake graphite, can be customized according to the specific requirements of users, packaging is packaged in the form of 25KG small bag sets, contact telephone: 18669737779 with WeChat, look forward to working with you. Scan the QR code below to add exclusive customer service, micro signal angdun
1. Structure of expandable graphite
Expandable graphite is currently widely used in steel structure fireproof coatings. Its chemical formula is C. It is a hexagonal crystal. The crystals are hexagonal plate and sheet. The appearance is scaly iron black, and the apparent density is 2.125g/cmз. The density is 0.1002-0.1004g / cm3, the surface is smooth, conductive, corrosion-resistant, and chemically inactive. Expandable graphite is prepared from natural flake graphite and sulfuric acid as intercalation agent. The intercalation of sulfuric acid plays a key role in the expansion of expandable graphite.
2. Flame retardant mechanism of expandable graphite
When the expandable graphite is subjected to a high temperature of 200 ° C or higher, the compound occluded in the layered lattice starts to decompose, and the expandable graphite exhibits several hundred times expansion along the C axis of the structure, and the volume reaches the maximum at 1100 ° C. . The gas phase product produced by decomposition of the compound is composed of S02, CO 2 and water. The expandable graphite is used in the fireproof coating of steel structure. When a fire occurs, the volume instantaneously blocks the flame, and the graphite after expansion becomes a worm-like shape with a low density. The structure is loose, porous and curved, has large specific surface area, strong adsorption force, low thermal conductivity, and excellent oxidation resistance and high temperature resistance.
The structural characteristics of expandable graphite determine that it will absorb a large amount of heat during the expansion process, its mass loss is small, low smoke, non-toxic, high performance, environmentally friendly, and will not react with other polymers, but it forms an expanded carbon layer. Insulation, oxygen barrier, also facilitate the cross-linking of other polymers in the coating into char.
Studies have shown that about 0.8% of SO2 is produced during the thermal decomposition of expandable graphite, which is equivalent to 16% of the total amount of sulfuric acid intercalated between the graphite layers. The thermal decomposition residue still contains a large amount of sulfur-containing substances, indicating that only a part of sulfuric acid is present. Participated in the reaction of the expansion of expandable graphite, a large number of redox gases are the main cause of expansion.
Expandable graphite still retains the properties of natural graphite, is not restricted by the environment, has good plasticity, ductility and sealing properties, and is used for the production of flexible graphite sheets, sealant fire extinguishing agents, fire retardant materials and the like. Currently widely used in petroleum, chemical, light industry, metallurgy, electric power, machinery, pharmaceutical, medical, automotive, marine, aerospace, military, nuclear energy and other high-tech industries. Shandong Shuangyu Carbon Co., Ltd. Specializing in the production of expanded graphite, high-purity graphite, flake graphite, can be customized according to the specific requirements of users, packaging is packaged in small bags, the phone number: 18669737779 with WeChat, look forward to working with you. Can add exclusive customer service, micro signal angdun