graphite electrode sizes
graphite electrode sizes
graphite electrode: synthetic process of fluorinated graphite
(1) High temperature synthesis method
This is the most commonly used method in the synthesis of fluorinated graphite, where graphite and fluorine gas are reacted directly at a certain temperature. The graphite is put into the reaction vessel in powder form, activated before the fluorine gas is introduced, and then a few hours of dry nitrogen gas is introduced, the volatile impurities in the reactant are removed, and finally fluorine gas can be introduced. The reaction temperature is 300 ~600℃, the reaction time varies from 1 to 200h. The type of graphite raw material, reaction time and temperature determine the composition of the obtained fluorinated graphite. The value of C/F in the molecular structure changes with the change of the reaction temperature.
(2) Low-temperature synthesis method
(3) Catalytic synthesis method
Catalytic synthesis means that when metal fluorides (such as LiF) are present, the reaction of graphite and fluorine gas can proceed smoothly at a temperature below 300°C. Among them, metal fluoride mainly plays a catalytic role, and the presence of metal fluoride can improve certain properties of fluorinated graphite, such as electrical conductivity.
The addition of metal fluoride can speed up the synthesis speed and improve the reaction conditions, but requires higher purity of the raw materials. For example, the fixed carbon content of graphite is required to be greater than 99.4%; the purity of fluorine gas is required to be 99.4% to 99.7%, in which the content of N2 is less than 0.3% to 0.6%, and the content of HF is less than 0.01%; the purity of the third-class metal fluoride is required to be greater than 98%. At the same time, the hazards of fluorine gas must be considered to ensure that the reaction is carried out safely.
(4) Electrolytic synthesis method
Between the two poles of the battery, graphite and hydrofluoric acid are electrolyzed due to the influence of the electric field, and an electrochemical reaction occurs to generate fluorinated graphite. The electrolysis process can be controlled by the concentration of the reaction solution, the reaction temperature and the amount of electrolyte. However, the degree of fluorination is low, and the product F/C is not uniform. The process of this method is still being further improved.
(5) Solid-solid synthesis method
This method uses solid fluoropolymer and graphite mixed, heated to 260 ℃ in an inert gas to make fluorinated graphite. This synthetic method has improved safety, but the degree of fluorination is low, and the product is uneven.
Further optimization of the synthesis equipment, reaction conditions and raw material properties of fluorinated graphite plays a very important role in improving the efficient, safe and environmentally friendly production process, and is also the basis for further expanding the application field of fluorinated graphite.
As a high-tech, high-efficiency fine functional material, fluorinated graphite has a series of unique physical and chemical properties, and it can be foreseen that its application range will continue to expand. At present, the United States, Japan and other countries have formed the scale of industrialization, but my country’s graphite fluoride is still far from large-scale industrialization.