INVESTIGATION OF THE PROCESS OF OBTAINING PYROCARBON IN AN ELECTROTHERMAL FLUIDIZED BED

Carbon materials with a wide range of performance properties are used in various science, technology, and industry fields. For example, Pyrocarbon has the prospect of being used in nuclear power engineering, special metallurgy, aerospace technologies, heat exchange equipment, medicine, mechanical engineering, reactor building and other industries. The research described in the article aims to study the process of obtaining pyrocarbon in an electrothermal fluidized bed. The research is based on experimental methods of studying the process of obtaining pyrolytic carbon. Pyrocarbon is precipitated during pyrolysis (thermal destruction) of hydrocarbons in an electrothermal fluidized bed reactor. Natural gas was used as a fluidizing agent, and crushed fine electrode graphite of the GE model was used as a fluidized bed. When producing batches of pyrocarbon material, taking into account that the particle size will increase, these particles were crushed and subsequently used as a fluidized bed, thereby replacing graphite with pyrocarbon. As a result of the experimental studies carried out in the reactor with the electrothermal fluidized bed reactor, the batches of pyrocarbon material that were produced based on artificial graphite were produced. Studies using electron microscopy showed a change in the color and structure of the pyrocarbon coating depending on the processing cycle in the electrothermal fluidized bed reactor at temperatures of 900–1200 °C. Diffractometric analysis showed that pyrocarbon was identified in the treated material. Therefore, the adequacy of the method for calculating the heat balance has been confirmed. Bibl. 36, Fig. 7, Table 1.

Analytical control of silicified graphite SG-P

An analytical scheme for the analysis of silicified graphite SG-P, a four-phase composite material consisting of silicon, carbon, silicon carbide and silicon dioxide, has been developed. The procedure can be successfully used in the quality control of raw materials and in the study of the phase composition of finished products The porosity and density of the graphite base, as well as the impurities contained in the base and silicon change the course of silicification and the properties of the finished product as well. The impurities are the main reason for the formation of delamination, swelling, cracking and light spots on the treated surfaces. It should be noted that the iron content 0.023 – 0.17 wt.% in the carbon material intended for silicification, leads to catalytic graphitization of the artificial graphite and dispersion in the silicon melt. Methods of rapid assessment of the quality of raw materials are to be used to provide quick understanding of their suitability for manufacturing final products on their base. Quality control of the silicified graphite produced at the JSC «Research Institute Graphite» is carried out by determination of the phase composition of the finished product by chemical and X-ray diffraction methods of analysis. The content of silicon carbide (not less than 45%), unbound silicon and carbon (not more than 20 and 35%, respectively) affects the corrosion resistance and thermal expansion of silicified graphite.

Achieving High-Performance Spherical Natural Graphite Anode through a Modified Carbon Coating for Lithium-Ion Batteries

The electrochemical performance of modified natural graphite (MNG) and artificial graphite (AG) was investigated as a function of electrode density ranging from 1.55 to 1.7 g∙cm−3. The best performance was obtained at 1.55 g∙cm−3 and 1.60 g∙cm−3 for the AG and MNG electrodes, respectively. Both AG, at a density of 1.55 g∙cm−3, and MNG, at a density of 1.60 g∙cm−3, showed quite similar performance with regard to cycling stability and coulombic efficiency during cycling at 30 and 45 °C, while the MNG electrodes at a density of 1.60 g∙cm−3 and 1.7 g∙cm−3 showed better rate performance than the AG electrodes at a density of 1.55 g∙cm−3. The superior rate capability of MNG electrodes can be explained by the following effects: first, their spherical morphology and higher electrode density led to enhanced electrical conductivity. Second, for the MNG sample, favorable electrode tortuosity was retained and thus Li+ transport in the electrode pore was not significantly affected, even at high electrode densities of 1.60 g∙cm−3 and 1.7 g∙cm−3. MNG electrodes also exhibited a similar electrochemical swelling behavior to the AG electrodes.