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 can be heated and expanded to form vermicular expanded graphite. The Franli factory uses low temperature and high temperature to study whether the properties of expandable graphite with different contents will change with the change of temperature.
Advantages of Expandable graphite
The technology of expansible graphite releasing into smoke is mainly divided into combustion dispersion, explosion dispersion and airflow dispersion. Among them, the airflow dispersion method has the advantages of quickly forming a large area, controllable smoke screen and long smoke screen release time, and has a good application prospect. Different from the combustion and explosion dispersion methods, which can provide sufficient heat for the expansion of expandable graphite in an instant, airflow dispersion generally uses aero-engine exhaust to release expandable graphite, which can only provide heating airflow below 800 ° C, and heating. time is limited. Therefore, it is necessary to conduct in-depth research on the performance characteristics of expandable graphite at low temperature expansion.
Changes in expandable graphite at low temperature
Franli factory conducted research and comparison of low temperature expansion through samples. Sample A used CH3COOH/HNO3/KMnO4 as the oxidation intercalation system to prepare expandable graphite, and sample B used H2O2/H2SO4/KMnO4 as the oxidation intercalation system to prepare expandable graphite.
(1) Expansion temperature: First, the initial expansion temperature of the expandable graphite was tested by scanning calorimetry, and the initial expansion temperature was determined by the heating method in a constant temperature oven. A certain amount of the sample to be tested was spread out in an evaporating dish, placed in a constant temperature box set at a certain temperature, and the sample was taken out after 30 minutes, and its volume was measured with a graduated cylinder. After measurement, the exothermic heat of decomposition of the pinch layer material in sample A is smaller than that of the pinch layer material in sample B. Comprehensive analysis shows that the initial expansion temperature of sample A is 150~160℃, and the initial expansion temperature of sample B is 220~230℃.
(2) Expansion volume: Franli factory found that the expansion volume of sample A was larger than that of sample B before 500 °C, and the expansion volume of sample B was larger than that of sample A after 500 °C. As the temperature increased, the volume difference increasingly obvious.
Influence of expandable graphite at high temperature
The high temperature expansion method is to put the expandable graphite into a high temperature environment to rapidly expand, and generally use a muffle furnace to quickly process the expandable graphite at high temperature. The Franli factory has studied the effect of expansion temperature on expansion volume. The results show that when the expansion temperature is 900 °C, the expansion effect of expandable graphite is good, and the expanded graphite has a developed pore structure and a large expansion volume.
Using 60 mesh flake graphite as the raw material, and selecting sample A as the intercalation oxidation system to make expandable graphite, after chemical oxidation, it expands at a high temperature of 1000 °C, and the expansion volume is higher than 160 mL·g -1 and the expansion ratio is as high as 375 times. Expanded graphite.
The Franli factory conducts various tests and analysis of expansion temperature, expansion volume, etc. through different types of expandable graphite, and compares the difference between high temperature and low temperature: low temperature expansion can ensure the expansion volume of graphite, reduce power consumption, and save costs; high temperature expansion It is widely used in various factories, but the heating time is long, the power consumption is also large, and the cost is wasted. Expandable graphite from the Franli plant is widely used for low temperature expansion, making efficient use of raw materials.
