Heat-treated nano-structured shungite rocks and electrophysical properties associated

Abstract

Shungite rocks of two different types were treated at ∼ 1400 • C and a set of nanomaterials have been obtained. Among the different materials obtained were: carbon hollow fibers; spherical or ellipsoid particles; silicon carbide amorphous; crystalline nanofibers and nanoparticles having different morphologies; iron and iron silicide nanoparticles encapsulated into carbon shells. Measurements were performed for shielding effectiveness (SE) and the electrical conductivity (σ) of untreated and heat-treated shungite rocks. The shungite rock with dominated hyperfullerene carbon is remarkable for a twofold increase in the σ and a 10 dB increase in SE with a slight decrease of the carbon content by 1.5 % in relation to the untreated sample. In contrast, the treated shungite rock with high SiC nanofiber content is characterized by a halving of the σ and a 10 dB decrease in SE with a decrease of the carbon content by 6 % relative to the original sample.

Electrophysical Properties and Structure of Natural Disordered sp2 Carbon

“…Therefore, materials based on natural carbon with a thickness of about 10 μm can be used in technological devices in conditions of very limited space. The electromagnetic radiation protection characteristics of carbon-based geomaterials can be easily adjusted and improved by adjusting the appropriate carbon content of the material or by modifying them thermally or chemically [ 70 , 102 , 103 , 104 , 105 ].…”

Organobentonite Binder for Binding Sand Grains in Foundry Moulding Sands

“…Significant changes within the structure occur at temperatures above 2100 °C, which is probably related to an increase in coherent dispersion regions and a reduction in the distortion of the carbon layer. On the other hand, shungites in rock deposits are characterised by such fragmentation and dispersion of minerals within the structure and a large contact area between carbon and mineral constituents that provide high carbon and silicon content, which determines the possibility of their mutual crystallogenesis, including the formation of carbides and silicides in the temperature range from 1400 to 1600 °C [ 33 ].…”

“…Currently, the area of application for shungite, taking into account the characteristics of this material, includes metallurgy (where it is introduced into the process instead of coke and graphite) and the production of non-stick coatings, radar structures, heat-insulating and high-resistance materials, catalysts for various chemical processes, and fillers for acid-resistant and refractory materials [ 32 , 33 ].…”

Mechanochemically Activated Shungite as an Additive to Improve Bitumen Characteristics

“…By processing shungite rocks at a temperature of 1400°C, a set of nanomaterials was obtained [Kovalevskii et al, 2018]: hollow carbon fibers, spherical or ellipsoid particles, crystalline nanofibers and nanoparticles, as well as iron and iron silicide nanoparticles encapsulated in carbon shells. A disadvantage of the method is the high processing temperature.…”