Composite Material Samples Research Articles

Adsorption Performance and Photocatalytic Activity of La-TiO2@kaolin Composites

Abstract La-TiO2@kaolin(LTK) composites were prepared via sol-gel method with kaolin, lanthanum nitrate and tetrabutyl titanate as raw materials. The samples were characterized by XRD, SEM/EDS, and UV-Vis. The visible light photocatalytic reduction activity and adsorption performance of samples for Cr(VI) were studied. The results showed that La doping can refine TiO2 grains, stabilize phase structure of anatase TiO2, and expand its absorption spectrum, thereby enhancing its photocatalytic reduction activity. Due to the composite of kaolin, the dispersion of TiO2 is improves and it is endowed with a large specific surface area lead to enhance its adsorption ability for Cr(VI). The adsorption equilibrium process of LTK for Cr(VI) conforms to the Langmuir equation model. The coupling effect of doping and composite modification improves the adsorption and visible light catalytic reduction activity of Cr(VI) over composite material samples. The adsorption-photocatalytic removal rate of LTK for Cr(VI) under visible light irradiation for 6 hours reached the highest of 96.5%. The apparent first-order kinetic constant of its photocatalytic reduction reaction was 2.6 times that of pure TiO2.

ВЛИЯНИЕ ШУНГИТА НА ТВЕРДОСТЬ КОМПОЗИЦИОННОГО МАТЕРИАЛА НА ОСНОВЕ ПОЛИЭТИЛЕНА ВЫСОКОГО ДАВЛЕНИЯ

Experimental samples of composite material based on high-pressure polyethylene 16803-070 filled with dispersed shungite, a natural environmentally friendly filler, have been obtained. High-pressure polyethylene and shungite were combined in a single-screw laboratory extruder. The effect of shungite on the mechanical properties of the presented composite material has been established. An analysis of the obtained experimental data has been conducted, which has shown that dispersion of shungite in the binder volume in an amount from 20 to 35 mass. % allows increasing the hardness of high-pressure polyethylene. The studied samples have been subjected to secondary processing. In the process of analyzing its results, the possibility of recycling the obtained material with a deterioration in its mechanical characteristics by no more than 4 % has been revealed

Carbon-carbon composite material as a potential basis for orthopedic implants

Aim. To determine the cytocompatibility of carbon-carbon composite materials (CCCM) and assess their ability to be impregnated with vancomycin.Materials and Methods. The study included samples of carbon-carbon composite materials (CCCM). The cytocompatibility of CCCM blocks was evaluated using a culture of eukaryotic cells (Vero cell line). Biofilms of S. aureus ATCC 29213 (MSSA), S. aureus ATCC 43300 (MRSA), S. epidermidis ATCC 12228 (MSSE), and S. epidermidis ATCC 29887 (MRSE) were formed by immersing sterile test samples of CCCM into a nutrient medium which contained bacteria. After 24-hour incubation, the samples were washed, placed in an ultrasonic bath, and sonication fluid was inoculated using the sector method. To saturate the CCCM blocks with antibiotics, they were placed into a vancomycin solution and then lyophilized under negative pressure with gradual heating. The antimicrobial activity of the resulting blocks was studied using the cup plate method against the same reference cultures of staphylococci. The dynamics of vancomycin elution from CCCM was investigated using high-performance liquid chromatography.Results. Vero cells maintained their viability in the presence of the tested material. Considering the highly porous structure of CCCM and variable diameter of the pores, we suggested a good osteointegration potential of this material. On the samples without an impregnation with an antibacterial drug, reference strains of staphylococci were able to form a biofilm with a sufficient number of bacterial cells to initiate an infectious process. The duration of antimicrobial activity of the antibioticim-pregnated samples against the reference staphylococcal strains was up to 3 days. The majority of the antibiotic eluted from the CCCM into the incubation medium during the first two days.Conclusion. The cytocompatibility and porosity of CCCM in combination with a vancomycin impregnation makes this material promising for the fabrication of implants with antimicrobial activity as well as tissue engineering constructs.

Lightning damage characteristics of Cf/SiC based on ultrasonic and multi‐nondestructive testing methods

AbstractAccording to the characteristics of the internal damage of the Cf/SiC composite material after the lightning strike, this article establishes a high‐energy ultrasonic excitation, reception, and high‐resolution ultrasonic testing model, achieving high‐energy and high‐resolution ultrasound C‐scan detection of Cf/SiC composite material samples after lightning strikes, and combining digital X‐ray and computed tomography methods for damage analysis. When the lightning energy is gradually increased, the lightning stratified damage will occur inside the sample, and the delamination damage area reaches the maximum value of 25182 mm2 at the lightning energy of S4. Subsequently, as the energy increases, significant needle‐like damage is generated at the needle‐stitched area inside the sample, and the area of delamination damage gradually decreases. When the energy continues to increase to the lightning strike energy of S6, as the energy increases, the number of needle‐like damage in the sample continues to grow, and penetrating injury appears at the needle suture site. At S8, the maximum number of needle‐like lightning damage occurred, with 53 damage points and a total volume of 256.86 mm3, respectively. Through comprehensive analysis, Cf/SiC has excellent resistance to lightning damage, but the needle‐stitched carbon fiber in the thickness direction significantly reduces its resistance to lightning penetration.

Influence on the properties of TMCs of ceramic and intermetallic composite reinforcements (B4C, TixAly and TixSiy) fabricated by inductive hot pressing

Ambitious and competitive, the aerospace industry continuously demonstrates to be one of the leading engineering sectors either at exigence and new technologies development. As lightning the weight of aircrafts is one of the main targets, the spotlight is usually on material research by which new ones may be produced to pursue this aim and still offer the necessary performances. The combination of the properties of titanium and other materials as reinforcements provides really interesting results as titanium matrix composite materials, also known as TMCs. Various samples of titanium matrix composite materials with different reinforcements have been under study to determine the influence of the reinforcements and their respective proportions on the properties of the material. These samples composed of grade 1 commercially-pure titanium as matrix and B4C, TixAly and TixSiy as reinforcements, have been manufactured through powder metallurgy in the same conditions of temperature and pressure via Inductive Hot Pressing (IHP). A total of eight composite materials have been arranged in several different groups to confront their compositions. Thus, this analysis reports results for the influence of the powder size of the matrix and the ceramic reinforcement, the effect of varying the volumetric composition of B4C, and the selection of different intermetallic reinforcements. These tests and the obtained information serve for a project in which the main goal is to determine which compositions of the studied composite materials reach a high enough specific stiffness for a suitable application in the aerospace industry.

Магнетит как функциональный наполнитель эластомерных композитов: эффекты размерности и структурирования

Samples of composite materials based on Fe3O4 magnetite with different particle sizes (natural and crushed in a planetary mill) and various elastomeric matrices (chloroprene rubber of sulfur regulation – PCP, styrene butadiene rubber - BSK and cold-cured polydimethylsiloxane – SKTN-A) in the concentration range of 10...200 weight parts per 100 weight parts of elastomeric matrices. The kinetics of curing of the elastomeric compositions under consideration has been studied, on the basis of which optimal molding modes have been proposed. The samples were formed both in the presence of a magnetic field up to 0.3 T and without it. The functional (electrophysical and magnetic) properties of the samples were studied and it was shown that these properties in a wide range of values can be regulated by changing the size of magnetite particles and/or structuring them by means of a magnetic field during the molding of elastomeric composites.

Experimental and numerical investigation on crack propagation in biomimetic nacreous composites with gradient structures

Combining interlocking structures and gradient design, this paper proposes a 2D biomimetic nacreous composite material with a gradient interlocked structure. Experimental and numerical simulation methods are employed to investigate the initiation and propagation behavior of cracks in the regular interlocking and gradient interlocked biomimetic nacreous composite materials. Samples of biomimetic nacreous composite materials with pre-existing cracks are manufactured using 3D printing technology, and uniaxial tensile tests are conducted to explore their crack propagation behavior. For biomimetic nacreous composite materials with periodic interlocking structures, the interlocking angle is found to play an important role in the toughening mechanism of composites. In biomimetic composite materials with large interlocking angles, crack inhibition effects are achieved through structural gradient design, effectively preventing catastrophic failure. Within the numerical analysis framework, a cohesive zone modeling approach is employed to represent the softer phase of the material, and the numerical simulation are validated by direct comparison with experimental results. In addition, a comprehensive numerical analysis is carried out to comprehend how the structural gradient affects the spread of cracks in these nacreous composites. This research not only illuminate the underlying deformation and toughening mechanisms intrinsic to interlocking nacreous composites but also pave the way for innovative strategies in the design of biomimetic materials through the incorporation of structural gradients.

Birefringent optical fibers to decouple thermo-mechanical effects on FBG sensors

Optical fiber Bragg (FBG) sensors are gaining importance in structural health monitoring (SHM) systems due to their compact size and ability to be embedded into the lamination sequences of composite material elements. A significant challenge, widely discussed in the literature, concerns the decoupling of thermomechanical measurements made through these sensors. This work aims to solve this problem using birefringent optical fibers instead of conventional ones. The distinctive characteristics of birefringent fibers allow an FBG sensor, written in such fibers, to present not a single peak but two distinct peaks, each with different responses to changes in strain and temperature. This is due to the different refractive index distribution in the fiber core section, which allows for two axes on which the light signal propagates at different speeds. This property offers a significant advantage: by having two independent equations associated with the two peaks, it is possible to decouple the thermomechanical measurements using only the fiber itself, without the need to introduce additional components to achieve mechanical decoupling (capillaries with through or interrupted fiber). This would ensure that strain and temperature are measured at the same point. In the first phase of the work, an FBG sensor on a birefringent fiber was characterized and subsequently calibrated. Therefore, a dedicated experimental set-up was created to conduct thermal, mechanical, and thermomechanical characterization tests, in order to verify the feasibility and effectiveness of decoupling. In a second step, such sensor was embedded within a sample of composite material (unidirectional glass fibers), which was subsequently subjected to the same characterization tests conducted on the single fiber. The results highlight the ability of this new transducer to decouple the thermal effect from the mechanical effect, allowing this new technology to overcome the problems of FBG sensors made of standard fibers.

Preparation of CrB2 mixtures and formation of briquettes for drill bit composites

The research described in the article concerns advanced methods of creating composite materials for drill bits used in extreme conditions of deep wells. The main attention is paid to development of multicomponent mixtures that ensure uniform distribution of powders of tungsten carbide, cobalt, chromium diboride and diamond. This is achieved through careful selection of particle size and proportions, which is critically important to ensure high strength and wear resistance of final materials. The Spark Plasma Sintering (SPS) method was chosen for the production of samples of carbide matrices and composite diamond-containing materials because of its ability to provide high density and uniformity of the material. SPS allows temperature and pressure control during sintering process, which contributes to the formation of materials with optimal physical properties. The article also discusses in detail design parameters of the diamond bit, including the choice of grain size of diamond powder and other components. These meters have been optimized to max-imize drilling efficiency and extend tool life. The diamond powders used in study were obtained from De Beers, South Africa and are characterized by high quality and uniformity. The results presented in the article can have a significant impact on future production of drilling tools, offering new approaches to choice of materials and methods of their processing, which ultimately can lead lower drilling costs and increased process safety. These innovations can also contribute to more efficient development of new fields, which is of great importance for the energy industry and the mining industry.

Fabrication of low-cost metal polishing machine for preparation of microstructure samples of lightweight alloy and composite material

A metallographic specimen should be performed to determine the microstructure of a material. One of the processes of preparation of metallographic specimen is polishing process. The designing and manufacturing a polishing machine will be very helpful in the process of polishing the metallographic specimen. This apparatus includes a motor, aluminum circular disc, switch and speed controller, and base plate. The polishing machine is constructed from these individual parts. This paper is proposed to design and fabrication a metal polishing machine for laboratory scale. In this paper, several stages of the process are performed, such as designing the model, preparing tools and materials used, making components, assembling and testing the polishing machine. The results obtained are polishing machine that works well and can be used for the metallographic test for students and researchers. It can be concluded that this polishing machine can produce the level of specimen preparation for a metallographic test.

Modeling of ice-matrix composite fracture

This article discusses the results of a study that used the structural approach to conduct multiscale modeling of composite materials. These materials are composed of an ice matrix that has been enhanced with high-strength basalt fibers. The research involved numerical modeling to analyze the fracture process of composite materials made by freezing fresh water with added basalt fibers. The analysis included experimental data from samples of pure ice and composites with different amounts of filler. The effective modulus of elasticity of the composites was determined by considering the quantity of basalt fiber reinforcement. The discrepancy between the strength obtained by finite element complex ANSYS numerical calculation and the experimental data was revealed by a series of macroscopic test calculations of the composite material sample, according to which the effective modulus of elasticity of the composite was recalculated and corrections were introduced into the Voight and Reuss models, taking into account the non-uniform distribution of the fibers and the non-ideal adhesion between the fibers and water ice. A stochastic model of crack growth at the micro level was also used with the data on the diameter and length of basalt fibers and their random distribution in the layers of the composite material. Using the newly acquired effective elastic moduli and the SmartCrackGrowth algorithm, a satisfactory agreement of the crack growth rate with the obtained by stochastic calculation was achieved. The refined method of effective elastic moduli and multilevel model of stress-strain state calculation of composite materials are recommended for assessing the strength of ice cover and designing winter roads with high load-bearing capacity and long operational duration in the Arctic and Subarctic environments.

Measurement of Strength and Fracture Load of Weathered Samples of Polymer Composite Materials

Measurement of Strength and Fracture Load of Weathered Samples of Polymer Composite Materials

ИССЛЕДОВАНИЕ ВЛИЯНИЯ СОСТАВА КОМПОЗИТОВ, СОДЕРЖАЩИХ ИМПАКТНЫЕ АЛМАЗЫ, НА ИХ ЭКСПЛУАТАЦИОННЫЕ ХАРАКТЕРИСТИКИ ПРИ ЛЕЗВИЙНОЙ ОБРАБОТКЕ ЦВЕТНЫХ МЕТАЛЛОВ

The paper presents the results of resistance tests of tool composite materials containing nanostructured impact diamonds, in comparison with composites based on synthetic superhard materials, diamond and cubic boron nitride (cBN), and ВК-8 (VK-8) (WC + 8 % Co) hard alloy, during blade processing of workpieces made of brass ЛС-59 (LS -59) (57–60 % Cu) and aluminum alloy AK-7 (Al 92–94 %, Si 6–8 %). Samples of composite materials for wear resistance studies were obtained by thermobaric sintering in a highpressure apparatus. The performance of composites was assessed by the wear of the cutter back surface, as well as by a specially developed method for studying the performance characteristics of composite superhard materials, based on determining their specific productivity. As a result of the tests, it is found that composites based on impact diamonds have the highest resistance when turning non-ferrous metal alloys. In particular, the wear resistance of a composite material containing impact diamonds with the addition of cBN exceeds the wear resistance of cutters made of composite 02 (belbor) by 1.5–3 times, and that of cutters made of hard alloy VK-8 by 8–10 times. Additions of impact diamond to hard alloy in the amount of 6.25 and 12.5 vol.% increase the relative wear resistance of the hard alloy composite compared to the original VK-8 alloy by 10–15 and 20–25 %, respectively.

Utilization of carbon-bonded magnesia refractory waste in MOC-based composites: Towards CO2-neutral building materials

In the steel industry, a large amount of diverse waste is generated, including carbon-bonded magnesia-rich waste originating from refractories. This study focused on the development and characterization of composite material based on magnesium oxychloride cement (MOC), with an emphasis on incorporating MgO–C-based refractory waste (CBMW) as a sustainable filler. To reach the best possible material properties, two different size fractions were applied in various ratios, completely replacing quartz sand. A comprehensive analysis of all composite material samples was conducted utilizing various analytical techniques, XRD, SEM, EDS or STA-MS. Mechanical properties such as compressive strength, flexural strength, and Young's modulus of elasticity were evaluated. Even though even the best sample did not surpass the mechanical properties for the reference, compressive strength 78.1 MPa was achieved, which is a more than sufficient value for most indoor applications.

Innovative methods of drying composite materials in vacuum

This work investigates innovative methods of vacuum drying of composite materials, providing improved preservation of physical and mechanical properties, reduced processing time, and lower energy consumption. A review of modern composite drying technologies is conducted, and the advantages of the vacuum method are identified. The methodoogy of an experimental study of the effectiveness of vacuum drying is presented, utilizing composite material samples and analyzing their properties before and after processing. The obtained results showed a significant improvement in strength characteristics and a 30 % reduction in drying time compared to traditional methods. A 25 % decrease in energy consumption was also observed. Statistical analysis confirmed the significance of differences in results between different processing methods. The advantages of vacuum drying are discussed, related to more uniform moisture removal and prevention of thermal damage to composites. Conclusions are drawn about the prospects of applying the developed methods in industrial production to improve quality and reduce costs.

ЭКСПЕРИМЕНТАЛЬНАЯ ОЦЕНКА ИЗНОСОСТОЙКОСТИ ПОЛИМЕРНЫХ МАТЕРИАЛОВ, ПРИМЕНЯЕМЫХ В ПОРШНЕВОМ КОМПРЕССОРНОМ ОБОРУДОВАНИИ

A new method is proposed for assessing the wear resistance of polymer materials according to the “finger — disk” friction scheme. It involves changing the geometry of the friction zone of polymer samples — the “finger” sphere is replaced by a truncated cone. The developed method is tested on samples of polyetheretherketone (PEEK) and polymer composite materials (PCM) based on polytetrafluoroethylene (PTFE, fluoroplast-4), in particular, obtained after laser ablation with the addition of carbon fibers. The relevance lies in simplifying the manufacture of samples, as well as the possibility of quickly changing the geometric parameters of their working part, which expands the scope of the method with respect to the latest polymer materials and composites based on them. The practical significance of the results is confirmed by their use at such enterprises as JSC “Grodno Azot” and JSC “Grodno Mechanical Plant”, which serially produce tribotechnical PCM.

Properties of ferroelectric composites in the microwave range

Ferroelectric ceramics of barium titanate and its solid solutions have found wide applications in technology, while compositions of a binary system with strontium titanate are most in demand. Electrically controlled components based on the barium titanate – strontium titanate ferroelectric ceramics are widely used in accelerator technology and the use of these materials is relevant at the present time. In the microwave range, composites based on the solid solution system barium titanate – strontium titanate ВаxSr1–xTiO3 (BST). Ferroelectric samples based on ВаxSrx–1TiO3 compound, where x = 0; 0.1; 0.3; 0.5; 0.7 were obtained using a conventional ceramic technology. The temperature dependences of the electrical properties of bulk ceramic samples based on ferroelectric composites were received in the temperature range 100°C to 350°C at a frequency of 1 kHz. It has been established that dielectric parameters significantly depend on the BaTiO3 content in BST compositions. To carry out a research in the frequency range from 0.1 to 8.5 GHz, an experimental setup was manufactured for measuring the electrical properties of ferroelectric materials based on an Agilent E5071C vector analyzer and a microstrip line. To conduct temperature studies, a microstrip line with a controlled sample was placed in a heat, cold and moisture chamber of the Bench-Top SU-261 series, in which it has been heated up to 60°C. The amplitude-frequency characteristics of the transmission coefficient (S21) of samples when heated from 20 °C to 60°C with an interval of 10 degrees were studied. The resonant frequency and quality factor of the resonator have been determined from the amplitude-frequency characteristic. Based on the value of the resonant frequency and the geometric dimensions of the sample, the dielectric constant of the sample material was calculated. It has been shown that with increasing barium titanate content (x = 0.1–0.3), the dielectric constant of the samples under study increases, and the resonant frequency shifts to lower frequencies. For samples with a barium titanate content of 50% and higher (x≥0.5), there are no resonance dependences and strong absorption of electromagnetic waves is observed. It has been established that with increasing temperature, the resonant frequency of composite material samples shifts to higher frequencies. Frequency dispersion of the dielectric constant is observed, which indicates the relaxor properties of the ceramic samples under study. Experimental investigations were carried out using a microwave strip line, a coaxial measuring cell and a capacitive converter; this made it possible to measure the dielectric constant of materials with values of more than several hundred in the microwave range and significantly reduce the control time when conducting thermal studies. It was shown that with a change in temperature, the electrophysical properties of the samples change significantly, which can be used in various systems and devices to change the reflection coefficient and phase of the electromagnetic wave.

Structure, soft magnetic properties of Fe-based magnetic composites and its practical application

A multi-stage technique for applying insulating coatings to metal powder particles has been developed in order to create a new class of Fe-based soft magnetic materials with improved characteristics. The density value calculated from the data of X-ray diffraction analysis is approximately 3 % higher than the experimentally measured values, which are 7.4–7.45 g/cm3. The low porosity of the composites is confirmed by the SEM and EDX results. The proposed method of encapsulation of iron powder with an oxide layer is a highly economical method for applying coatings of various chemical compositions to metal powders, and can be widely used in practice to obtain electrical materials. Comprehensive studies of the properties of the obtained samples of powder composite materials based on ABC100.30 iron, the particles of which are encapsulated with phosphorus oxide, have been carried out. It has been established that in a field of 1.5 T, the losses at a frequency of 1 kHz decrease 10 times with an increase in the thickness to 30 nm. The synthesized materials are recommended for use in the development of various types of high-frequency electric motors, generators, chokes, magnetic circuits and electrodes for high-frequency welding and other applications.

Влияние термической обработки на свойства композиционных материалов АМг2–10%TiC и АМг6–10%TiC, полученных методом самораспространяющегося высокотемпературного синтеза

Dispersion-strengthened composite materials belong to the group of promising structural materials characterised by a diverse combination of properties. The paper considers examples of the creation and heat treatment of composite materials based on aluminium alloys strengthened by the titanium carbide dispersed phase characterised by high hardness, elastic modulus, and good melt wettability. At present, self-propagating high-temperature synthesis (SHS) is the most accessible, inexpensive and effective way to obtain them. The authors substantiate the expediency and show their successful experience of the formation in the composition of the AMg2 and AMg6 industrial alloys of a titanium carbide dispersed phase with a particle size of 130 nm in an amount of up to 10 wt. % using the SHS method, which makes it possible to increase the hardness of the alloys. Additional heating of the AMg2–10%TiC and AMg6–10%TiC samples after synthesis also contributes to the further increase in hardness. The complex of studies of physical, mechanical and operational characteristics presented in the paper was carried out to compare the properties of the work-hardened matrix alloys and the samples of composite materials before and after heating. The test results showed that heat treatment reduces the porosity of the composites and significantly increases their hardness and microhardness. A slight decrease in compressive strength at a significant increase in wear resistance is observed. It was found that composite materials are characterised by high corrosion resistance to carbon dioxide and hydrogen sulfide corrosion corresponding to the level of matrix alloys. The results obtained allow recommending the developed materials for the production of parts of the connecting rod and piston group, bearings and other wear-resistant parts of friction units.

Study of the structure of fibrous composite material using computational x-ray tomography

the article discusses the determination of the actual porosity and the actual volumetric content of the reinforcing material and binder in a sample of fibrous polymer composite material (FPCM) using the non-destructive method of computational x-ray tomography. It is shown that the linear attenuation coefficient (LAC) of X-ray radiation in the volume of the sample under study based on the set of integral shadow projections obtained by X-ray transmission in various directions and its root-mean-square deviation (RMSD) provide sufficient information about the parameters of the microstructure of the sample under study. To obtain quantitative characteristics of porosity and volumetric content of components, it is necessary to examine test samples made from similar components with previously known various parameters of the material structure in the required range of scatter of these characteristics. The proposed method can be used as a non-destructive control of the structure parameters of critically important products made of VPCM, both in general and in selected local areas of the product. Also, this method is recommended for determining the actual porosity and the actual volumetric content of the binder when carrying out research work on the influence of VPCM structure parameters on the durability and residual strength of samples when exposed to external factors during operation, in particular when carrying out certification work on elementary samples.