US President recently decided to invoke a Cold War-era defense law to encourage domestic expandable graphite.
Expandable graphite - a special type of graphite.
Due to the laminar structure of graphite, atoms or small molecules can be introduced between the carbon layers (intercalation). During this process, so-called swellable graphite salts or GICs (graphite embedded compounds) are produced. Excellent grades of expandable graphite have a high percentage of intercalation layers. Usually sulphur or nitrogen compounds are used as insertion agents. Under the influence of heat, these layers separate like an accordion and the graphite sheet expands.
Depending on the grade of material, expansion can start at as low as 180°C and can occur suddenly and rapidly. In the case of free expansion, the final volume may be hundreds of times larger than the initial volume. The properties of expandable graphite, i.e. the initial expansion temperature and the degree of expansion, are mainly determined by the quality of the insert (the proportion of the insert) and the inserting agent.
Expandable graphite as a flame retardant.
One of the main applications of expandable graphite is as a flame retardant. Due to the heat of the fire, the graphite expands and forms an intumescent layer on the surface of the material. This delays the spread of the fire and minimises one of the most harmful effects of combustion, namely the production of toxic gases and smoke.
How to produce expandable graphite?
To produce expandable graphite, natural graphite flakes are treated in a bath of acid and oxidizing agent.Usually used oxidizing agents are hydrogen peroxide, potassium permanganate or chromic acid. Concentrated sulphuric acid or nitric acid are usually used as the compound to be incorporated, with the reaction taking place at temperatures of 30 °C to 130 °C for up to four hours. After the reaction time, the flakes are washed with water and then dried. Starting temperature and expansion rate depend on the production conditions and particle size of the graphite. temperature and expansion rate are depending on the degree of fineness of the graphite used.
What are the applications of expandable graphite?
One of the main applications of expandable graphite is as a flame retardant. When exposed to heat, expandable graphite expands and forms an intumescent layer on the material surface. This slows down the spread of fire and counteracts the most dangerous consequences of fire for humans, the formation of toxic gases and smoke.
By compressing expanded graphite, foils can be produced from pure graphite. These are mainly used as thermally and chemically highly resistant seals in chemical plant construction or as heat spreaders.
Expandable graphite for metallurgy
Expandable graphite is also used in metallurgy to cover melts and moulds. The material serves here as an oxidation protection and insulator.
Expandable graphite for the chemical industry]
Expandable graphite is included in the chemical processes for paints and varnishes.
High-quality expandable graphite supplier
Luoyang Moon & Star New Energy Technology Co., LTD, founded on October 17, 2008, is a high-tech enterprise committed to developing, producing, processing, selling, and technical services of lithium-ion battery anode materials. After more than 10 years of development, the company has gradually developed into a diversified product structure with natural graphite, artificial graphite, composite graphite, intermediate phase, and other negative materials (silicon-carbon materials, etc.). The products are widely used in high-end lithium-ion digital power and energy storage batteries.
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Trafigura, one of the world's largest metals traders, is to take a stake in a new company to supply car and battery makers in Europe with lithium from a refinery in the UK, the Financial Times reported. As part of the investment, Trafigura will seek raw material for Green Lithium, which plans to build a plant in the north of England capable of producing 50,000 tonnes a year and sell the finished expandable graphite, etc. If you are looking for high-quality materials, please feel free to contact us and send an inquiry.
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