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Two-dimensional and four-dimensional reinforced carbon–carbon composite materials based on carbon structural filament are prepared via the isostatic carbonization of a coal tar pitch. The difference between the crystalline state of a reinforcing fiber and a coke matrix is assessed with X-ray diffraction analysis. A change in the level of the surface resistivity depending on the density of the samples and the degree of graphitization of a matrix is studied with eddy-current testing. We show that the degree of completion of formation of the internal structure influences the mechanical strength and the level of specific electrical resistance of the material. Measurement of the electrical resistivity with eddy-current testing appears to be a non-destructive method to assess changes in the structure of the material.

The application of the agricultural waste of cashew nut shells (CNSs) from the Ivory Coast is proposed for the production of activated carbon (AC) used in water treatment by the physical activation. Washed and crushed CNSs are carbonized at 800°C. The crushed CNS carbonizate is activated by the physical method in a temperature range from 400 to 700°C. The specific surface (SBET) and porous structure of the AC samples are investigated by low-temperature nitrogen desorption and X-ray structural (X-ray phase) analysis. The results show that an increase in the activation temperature at a fixed time leads to an increase in the material specific surface, the development of a microporous structure, and an increase in the summary volume of mesopores and micropores of AC. The X-ray phase analysis data shows that the degree of graphitization, interplanar spacing, and crystallite sizes vary insignificantly. The possibility of using CNSs to fabricate AC no worse in sorption properties than its analogs currently in use to purify water is proven.

Thermophysical properties are studied: thermal conductivity, heat capacity and thermal diffusivity of spatially reinforced carbon-carbon composite materials. A structural model is proposed for thermal conductivity levels at 300 and 2500 K. Results of calculations are confirmed in manufacturing practice and studies of material properties. It is shown that anisotropy of thermal conductivity levels leads to a nonuniform thermal state of refractory carbon composite working surface fragments. It is established that structure formation for the surface of a carbon-carbon refractory wall is connected with composite components structural state inhomogeneity. Approaches are proposed for increasing the working surface life for refractory carbon materials.

The specific surface and porous structure of viscose-based carbon fibers produced by the Krasnoyarsk Plant of Chemical Fibers are investigated by low-temperature nitrogen adsorption using an ASAP 2020 device. The dependence of their specific surface and character of the pore-size distribution on gas-phase activation modes in the carbon dioxide stream at a temperature of 900°C is shown. It is established that the adsorption surface of carbon fibers can rise from 0.3 to 1900 m2/g during the activation. It is revealed that the prolongation of the activation time leads to an increase in the specific fiber surface owing to the appearance of numerous new micropores and the development of the microporous structure.