C/C materials represent as materials with specific performance, therefore they are applied in various industries. It is essential to figure out the paths to predict, to provide and to enhance their properties to obtain high performance products. It is well known that strong matrix/reinforcer adhesion provides better strength utilization and therefore better properties for the majority of composite materials of all types (Heim in Compos Part B Eng 54:365–370, 2013), (Hancock and Cuthbertson in J Mater Sci 5:762–768, 1970), (Yang et al. in Polymers 13:2764, 2021). However some researchers note that strong adhesion in the materials that are exposed to high temperatures leads to cracking and significant properties degradation (Vignoles et al. in The Control of interphases in carbon and ceramic matrix composites, Wiley, Hoboken, 2012), (Zhang et al. in Compos Struct 340, 2024). In this work, the effect of the pyrocarbon layer applied on the surface of carbon fibers used for reinforcement of formaldehyde novolac resin based carbon/carbon (C/C) material prepregs was investigated. For the first time we used this effect to prove that lower matrix/reinforcer adhesion in C/C materials prepregs leads to better material behavior during pyrolysis, which results in higher mechanical properties of the pyrolised samples in comparison with the samples demonstrating stronger matrix/reinforcer adhesion. The prepregs were thermally treated at various temperatures, the physical and mechanical performance evolution of the prepregs at different carbonization stages were analyzed. Comparative study of the features of the prepregs with pyrocarbon coated and uncoated carbon fiber as a reinforcement were carried out. The damping effect of the pyrocarbon on the fiber surface were advertised, allowing to mitigate the carbonization-caused effects. The prepregs reinforced with pyrocarbon-modified carbon fibers demonstrated lower cracking performance and higher mechanical performance comparing with the uncoated fiber reinforced prepregs.

The efficiency of fiber impregnation with a polymer melt is one of the most important components that make up the quality of the UD-prepregs and, subsequently, parts made of them. If thoroughly formulated, the mathematical impregnation model could assist to find the most suitable parameters to enhance the impregnation. Consequently, the investigation of the fiber bundle impregnation with the high-viscosity thermoplastic resin melt by pultrusion with impregnation die is represented. An approximate one-dimensional mathematical model of roving impregnation during pultrusion through an impregnation die which considers the polymer melt leakage into fiber bundle is established. The maximum total impregnation depth of fiber bundle depending on the various values of the pulling speed and the fiber tension is calculated. The results show that the calculations of the impregnation depth are hinge on the leakage consideration, as well as on pulling speed and tension.

Exfoliated graphite (EG) is a promising macroporous sorbent for oils and liquid hydrocarbons on water surfaces. The preparation of EG includes a synthesis of graphite intercalation compounds, expandable graphite and its thermal exfoliation. The structure of the initial graphite intercalation compound (GIC) has a significant influence on the structure of exfoliated graphite and its sorption properties: sorption capacity and selectivity of water/octane sorption. Thus, the aim of this work was to investigate the relationship between the structure of EG based on 1st stage, 2nd stage, 3rd stage, 4th stage GICs and EG sorption properties and water wettability. The influence of the GIC stage number on the EG sorption and surface properties is studied. EG obtained from 1st stage GIC at 1000 °C is characterized by a higher sorption capacity toward octane than EG from 4th stage GIC. The selectivity of octane/water sorption reduces when decreasing the GIC stage number from 4 to 1. The high sorption of water can be explained by a higher surface area of EG and the presence of remaining oxygen groups on the edges of graphite crystallites in the EG structure. The EG structure was investigated by XRD, SEM, nitrogen adsorption–desorption method, FTIR and Raman spectroscopy.

For small-scale and single production, FDM printing is considered as a technology competing with the well-known method – injection molding. However, due to the specifics of the printing process associated with layer-by-layer formation printed parts are significantly inferior to parts obtained by injection molding in terms of strength and surface quality, minimizing the advantages of 3D-printing. The methods that make it possible to improve the physical and mechanical characteristics of a printed parts include bulk treatment methods based on thermal effects on the whole part. The aim of this paper is to compare the technologies of bulk thermal post-processing in terms of the effect on the physical and mechanical properties of FDM-printed samples. Three methods of bulk thermal post-treatment are considered: annealing in a dispersed environment, annealing in a dispersed environment with pressure, annealing in a vacuum bag. The properties and deformations of ABS plastic samples printed by the FDM-method are investigated. The research results showed that all the considered technologies of bulk post-treatment of FDM-printed samples can be considered promising to improving physical and mechanical properties. The best results of minimizing deformations after annealing are observed after treatment in a dispersed environment consisting of gypsum powder. The obtained unsatisfactory results of changing the sizes of samples annealing in a vacuum bag may be related to the imperfection of this post-treatment method.

The application of additive technologies to the manufacture of polymer and composite products is now actively expanding. The FDM printing process is popular because of its ability to adapt to specific tasks and to bring products with complex geometries into production quickly and at minimal cost, and is seen as a technology that can compete with injection molding. However, due to the nature of the process, FDM printed parts are significantly inferior in quality to injection molded parts. Much attention is now being paid to research into supplementary treatment methods to improve the properties of FDM printing parts. However, there is no complete and clear description of such methods, nor are there any recommendations on the choice of treatment methods aimed at improving the specific parts properties. The aim of this review is to analyse the research in the field of post-treatment of parts in order to systematise their advantages and limitations, which will allow a more reasoned choice of a post-treatment method to improve specific properties of FDM printing parts. The bibliography includes 120 references.

FDM is used for printing parts from thermoplastic polymers, polymer matrix composites, biocomposites or polymer-ceramic composites, nanocomposites and fiber-reinforced composites. The main disadvantage of this method is the reduced physical and mechanical characteristics due to the presence of pores and poor adhesion of layers. The post-treatment is one of the ways to improve this properties. The heat treatment has the greatest impact among all types of post-treatment processing on the surface quality and physical and mechanical properties of finished products. The paper studies the physical and mechanical properties of samples from ABS plastic (REC brand) printed by FDM and subjected to thermal post-treatment. Two methods of thermal post-treatment were considered: in NaCl powder and in closed form with pressure. The test results of the printed samples were compared with the test results of the samples obtained by injection molding. Comparison of strength and porosity showed that the properties of printed samples after post-treatment by both methods are comparable to the properties of samples obtained by injection molding.

The article presents an overview of the methods of manufacturing prepreg based on thermoplastic and thermoset polymers, as well as an analysis of the tooling used for its manufacture. The advantages and disadvantages of prepreg with various matrix polymers and methods of their manufacture were considered. The paper presents a computer-aided design of a pultrusion head, which is an equipment of a pultrusion line for prepreg with a thermoplastic matrix. The tooling was designed according to a certain algorithm, taking into account the design features. The developed equipment can be used for the manufacture of narrow prepreg tapes for subsequent automated layout using AFP and ATL technologies. The shape of the working surfaces of the developed tooling makes it possible to achieve a high degree of impregnation of the continuous fiber with a thermoplastic polymer. The work created prerequisites for the further production of the developed equipment and the creation of a full-fledged line for the manufacture of tape prepreg.

Graphite foil (GF) compressed from exfoliated graphite (EG) is a sealing material, which is used in nuclear energy and the chemical industry. The preparation of graphite foil is a complex process, which includes the intercalation of graphite, water washing, thermal exfoliation and pressing of intermediate products. The preparation conditions significantly influence the structure of the material and its physicochemical properties. Thus, the aim of work was to reveal the correlation between GF processing conditions, its crystalline structure, porosity and gas permeability as well as thermal stability. Sealability of the material is connected with low value of gas permeability, while thermal stability allows use of the material in high-temperature processes. Optimization of these parameters allow for the obtaining of a reliable material and expanding of the areas of its application. Exfoliated graphite for GF was prepared at different temperatures of 600, 800 and 1000 °C from the H2SO4–graphite intercalation compound (GIC) of II, III, IV stages. The influence of the GF processing conditions (the GIC stage number and the EG preparation temperature) on the main properties (gas permeability and thermal oxidation stability) of the sealing materials was investigated. A decrease in GIC stage number leads to the formation of GF with lower macroporosity and lower nitrogen and hydrogen permeability. However, an increase in GF surface area leads to an increase in the rate of GF oxidation by air oxygen. An increase in the EG preparation temperature from 800 to 1000 oC results in the formation of EG with a developed micro- and mesoporosity and increasing GF gas permeability. A decrease in EG preparation temperature down to 600 °C promotes the formation of new transport macropores in GF. The change of the EG preparation temperature has little effect on GF oxidation stability.

Features of utilizing materials based upon thermally expanded graphite (TEG) as barrier materials in electric baths are considered in the article. Experience of industrial application of a graphite foil barrier layer for protecting the refractory part of reduction cells, and advantages and disadvantages of a graphite foil barrier material are analyzed. An area for improving the properties of the barrier materials with the help of antioxidation impregnation is proposed.

The study is aimed to deepen the understanding of the interrelation between density, open and closed porosity as well as gas permeability of compressed graphite foils with a density ranging from 0.5 to 1.8 g·cm−3 designed especially for sealing applications. The pore structure of the graphite foil samples is experimentally measured by several complementary methods: low-temperature N2 adsorption, method of saturation with liquids (hydrostatic weighting), mercury porosimetry, and helium leak detection for gas permeability measurement. A comparative study of the porosity obtained by mercury porosimetry and by saturation with water and isopropanol, made it possible to propose a reliable express method for determining and controlling the porosity of dense graphite foil. It was found that the characteristic pore size and open porosity of graphite foil decreases with increasing its density from 0.5 to 1.8 g·cm−3 leading to a decrease in helium gas permeability of the foils. An average capillary diameter, the number of capillaries and their effective cross-sectional area was calculated on the basis of the dependence of helium gas permeability on foil density and gas pressure. The obtained data were applied for describing the pore structure of the graphite foils with low density and explanation of their low gas permeability.

Composites consisting of propargyl- and allyl/propargyl- modified novolac resins and carbon fabric were obtained by the vacuum infusion molding process. It was established that the presence of potassium cations remaining after the synthesis increase the resin melt viscosity, and acid washing is needed to obtain resins suitable for cost-effective injection techniques of composite fabrication. The mechanical properties of all composites such as compressive strength, tensile strength, in plane shear strength, and interlaminar shear strength were determined at 25, 200 and 230 °С. The carbon fiber reinforced plastics (CFRPs) retained their mechanical properties at temperatures up to 200 °C. It was shown that the use of the obtained allyl-containing polymer matrices improved mechanical properties and increased the thermal stability of the CFRPs in comparison with the propargylated novolac matrices. The composite material with novolac matrices modified by 18% propargyl and 23% allyl groups retains only up to 70% of the initial interlaminar shear strength values at 230 °C which corresponds to the data of the dynamic mechanical analysis of neat cured resins.

We present the data on the improvement of carbon cathode lining materials used in the production of aluminum by electrolysis and discuss some issues from the materials science related to the technology of production of carbon cathode materials.

Graphite foil (GF) is widely used as a sealing material in different industries. Different methods of GF preparation result in differences of its crystalline and pore structure, which in turn influences its ability to pass through gases and provide the required level of sealability. The influence of the preparation temperature of exfoliated graphite (EG) on the microstructure and gas permeability of EG-based graphite foil was investigated. The preparation of graphite foil consisted of the synthesis of stage-1 graphite bisulfate, followed by washing with water, rapid heating of obtained expandable graphite at temperatures of 600, 800, 1000 °C with the formation of exfoliated graphite and the subsequent compression of EG into graphite foil. The structure of the materials was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Raman spectroscopy. The correlation between EG preparation conditions, the presence of amorphous and turbostratic carbon, which influence the GF porous structure and GF gas permeance, was found. Graphite foil based on EG obtained at 600 °C had the minimal nitrogen and hydrogen permeances of 0.11·10–10 and 0.44·10–10 mol m−2 s−1 Pa−1, while the increase in EG preparation temperature up to 1000 °C raises GF gas permeance.

NBR materials are widely used in oil refining, automotive industry and aviation due to the high tensile strength and elasticity, resistance to dilute acids. During operation with oils and fuels NBR materials undergo aging, which results in deterioration of the properties of materials [1]. The data on compressibility of NBR samples with 0, 1 and 10% zinc oxide and various cross-linking degree immersed in oil at 150°C for 5 hours and in gasoline at room temperature for 5 hours according to ASTM F146 – 12 [2] was collected. The cross-linking degree of NBR was calculated as the ratio of the heats of cure of samples vulcanized at specified temperate and time and unvulcanized samples as described at ISO 11357-5:2013 [3]. Compressibility was measured using a Tinius Olsen H5KS tensile testing machine according to ASTM F36 – 15 [4]. The data demonstrates the influence of vulcanized conditions and zinc oxide as a sulfur vulcanization activator content on compressibility change after deterioration in oil.

The main question for understanding the corrosion of a side lining made from silicon carbide based on a silicon nitride binder is whether corrosion of Si3N4–SiC material by gases (and, in particular, oxidation) is preceded by corrosion by molten electrolyte, or corrosion by molten electrolyte plays its own role in material degradation during service. It is more probable that reactions of SiC and Si3N4 with molten cryolite pass through a pre-oxidation stage. Calculations show that the majority of possible reactions of SiC and Si3N4 with oxygen, carbon monoxide, and carbon dioxide have a positive volumetric effect, which reduces material porosity, but may cause crack development within it. In this case the silicon oxide formed is dissolved in molten electrolyte and may also react with electrolyte components in the gas phase.

Nitrogen permeability of graphite foil (GF) based on expandable graphite with different oxidation degrees was measured. Expandable graphite was obtained by the chemical interaction of graphite and nitric acid with the formation of graphite nitrate of II, III, IV stages and by the electrochemical oxidation of graphite in HNO3 solution followed by water washing. The expandable graphite samples were heat-treated at 800 °C with the formation of exfoliated graphite followed by pressing the exfoliated graphite into GF. The samples of exfoliated graphite and graphite foil were investigated by XRD, SEM, Raman spectroscopy and mercury porosimetry methods. GF nitrogen permeance decreases from 19.7 × 10−10 to 6.7 × 10−10 mol m−2 s−1 Pa−1 with decreasing a stage number of graphite nitrate from IV to II. Gas permeance of GF based on electrochemical expandable graphite decreases by an order of magnitude up to 0.2 × 10−10 mol m−2 s−1 Pa−1 in comparison with GF based on graphite nitrate of II stage. Thus, it is possible to produce the graphite foil material with a wide range of permeability and, respectively, the different sealing efficiency by varying the oxidation degree of the initial graphite matrix in the step of obtaining graphite intercalation compounds and expandable graphite.