Dynamics of intercalated graphite compounds transformation at thermal shock heating
| Autor: | V. О. Maslov, L. О. Dan, L. О. Trofimova, Y. P. Pustovalov |
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| Rok vydání: | 2019 |
| Předmět: |
lcsh:TN1-997
Thermal shock Materials science lcsh:Mechanical engineering and machinery Materials Science (miscellaneous) розширення Dynamics (mechanics) Thermodynamics графіт з’єднання інтеркальованого графіту General Business Management and Accounting Industrial and Manufacturing Engineering Transformation (music) термографеніт насипна щільність термошоковий нагрів lcsh:TJ1-1570 Graphite Business and International Management General Agricultural and Biological Sciences lcsh:Mining engineering. Metallurgy |
| Zdroj: | Vìsnik Priazovsʹkogo Deržgavnogo Tehničnogo Unìversitetu. Serìâ: Tehnìčnì Nauki, Vol 0, Iss 38, Pp 23-30 (2019) |
| ISSN: | 2519-271X 2225-6733 |
| DOI: | 10.31498/2225-6733.38.2019.181270 |
| Popis: | Thermally expanded graphite (TEG) has a unique combination of properties: a wide range of operating temperatures, high chemical resistance, excellent sealing ability. That’s why it’s widely used in many industries. These properties result from the fact that intercalated graphite has the ability to expand many times in volume with the formation of low-density carbon material (thermographenite) at heating up to 900°C (thermal shock). Foaming is accompanied by the release of a large amount of gas vapor phase, creating an intralayer pressure of several hundred atmospheres; the pressure resulting in the expansion process. The present work has studied, the oxidation process during intercalation and expansion of graphite particles during thermal shock heating. GAK-2 graphite particles with +0,16 mm fraction were oxidized with concentrated sulfuric acid with potassium bichromate. The resulting product was expanded in the furnace in a gravitational-falling layer at temperatures of 200-1000°C. It has been found out that the minimum volumetric density of TEG (depending on specific conditions, that is varying from 2,5 to 5,2 kg/m3) is provided if the mass of oxidant and the mass of graphite.are in the ratio 0,3-0,5. The results of the study showed that intercalation causes swelling (expansion) of graphite particles. Due to this, the volume density of intercalated graphite decreases from 390 to 240 kg/m3; while the initial volume density of graphite is 420 kg/m3. The study of the microstructure of the particles of the initial, oxidized and thermally expanded graphite showed that with the same mean-median particle size, they expand along the normal to the surface and reach 4,5-7,7 times the size of the original mean median size. It turned out that small particles are more oxidized as compared to larger ones. Specific volumes have been obtained based on the dependence of the specific volume of thermographenite on the temperature of thermal shock heating for various samples of oxidized graphite, and reached 200-400 l/kg at 1000°C |
| Databáze: | OpenAIRE |
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