Material Yield Research Articles

Современное состояние почв лесных питомников таежной зоны Европейской части России

When producing planting material in the taiga zone, it is extremely important to assess problematic sites in forest nurseries. Attention should be paid to poor soil quality, which can significantly affect the growth rate of seedlings and the yield of standard planting material. The article considers a comprehensive assessment of soil conditions in forest nurseries of the taiga zone of the European part of Russia. The research was conducted in six forest nurseries. Agrochemical and physical properties of soils were determined. The content of organic matter in the soils of forest nurseries is low, mobile forms of phosphorus, exchangeable potassium and alkaline hydrolyzable nitrogen are insufficient for optimal growth and development of coniferous seedlings. The level of acidity in the soils of nurseries in the taiga zone of the European part of Russia turned out to be favorable. Half of the studied forest nurseries have increased density of soil composition, which can lead to the formation of soils with low pore volume, limiting air intake and moisture retention in the soil. A decrease in the intensity of seedling growth and yield of standard seedlings may occur due to the lack of technological measures such as weed control, lack of irrigation, etc., but one of the most important reasons is the insufficient supply of soils with mineral and organic substances. Equalization of soil fertility parameters in forest nurseries can be achieved by application of necessary fertilizers and by means of cultivation. The results of the presented work will make it possible to draw the attention of specialists engaged in the cultivation of planting material in the taiga zone of the European part of Russia to the problem of low soil fertility.

Strategic Insights for Bulk Production of MXene: A Review

The remarkable versatility of MXene materials has propelled them into the forefront of advanced material science, with applications spanning energy storage, catalysis, water treatment, and electronics. Bulk production of MXene materials is essential to meet the demands of applications, enhance commercial viability, support research efforts, integrate MXene into industries, and drive technological advancements. It is a key step in realizing the full potential of MXene materials and ensuring their widespread use in diverse fields. However, the problem is that MXene synthesis methods, especially those developed at the laboratory scale, face challenges when transitioning to large-scale production. Maintaining the quality, consistency, and yield of MXene materials on a large scale can be complex. The paper provides a comprehensive overview of current synthesis methods, critical parameters that influence bulk production, precursor materials and post-synthesis characterizations, and innovations in scaling up MXene production. The necessary environmental and safety measures were also reviewed. This comprehensive review work is critical for developing the area of MXene bulk manufacturing and has major implications for the larger community. By thoroughly addressing problems, investigating crucial factors, and emphasising breakthroughs in large-scale synthesis, the study serves as a road map for researchers, industry experts, and maybe policymakers.

ПЕРСПЕКТИВЫ ИСПОЛЬЗОВАНИЯ РОДОДЕНДРОНОВ В ГОРОДСКОМ ОЗЕЛЕНЕНИИ И ВОЗМОЖНОСТИ ПРИМЕНЕНИЯ БИОТЕХНОЛОГИЧЕСКИХ МЕТОДОВ ДЛЯ ИХ МАССОВОГО РАЗМНОЖЕНИЯ

The article assesses the use of introduced representatives of the genus Rhododendron L. in urban landscaping in central Russia. The species and varietal diversity of rhododendrons allows us to meet the highest demands of specialists in green construction and landscape architecture. Rhododendrons are a difficult-to-root crop, so there is a constant search for means and methods that can increase the yield of planting material. Along with traditional methods of plant propagation, the method of clonal micropropagation is successfully used. The prospects of biotechnological methods for mass propagation of rhododendrons are shown.

Modelling the Impact of Graphene Coating of Different Thicknesses on Polyimide Substrate on the Secondary Electron Yield

Polyimide material is widely used in the aerospace field, but its secondary electron emission yield is high. In this study, a graphene coating was used to suppress its secondary electron emission, and the secondary electron emission yield of graphene-coated materials with different thicknesses was calculated using the GEANT4 numerical simulation method. The suppression effect of different thicknesses of graphene coatings on the secondary electron emission was analyzed. The simulation results showed that the optimal graphene coating thicknesses for the lowest secondary electron yield of polyimide materials were 1 nm and 5 nm, which reduced the secondary electron emission yield by 13% in terms of simulation. The 5 nm graphene coating reduced the secondary electron emission yield by 6% compared to the polyimide material from an experimental perspective. The 5 nm coating showed better results at higher energies and was experimentally verified by preparing five layers of graphene coating, which showed good agreement between the simulation and experiment. Meanwhile, with the increase in graphene coating thickness, the surface secondary electron emission displacement range decreased, and the secondary electrons produced at the surface were of low energy. The results of this study can provide technical reference for polyimide in aerospace applications and secondary electron emission simulation.

Flash annealing of a chemically heterogeneous medium Mn steel

Medium Manganese Steels (MMS) are considered among the most promising 3rd generation advanced high strength steels. However, their practical production and application have been constrained by factors such as relatively high Mn content, low yield strength and the occurrence of Lüders banding. In this contribution, flash heating and the concept of chemical heterogeneity were combined to engineer an MMS variant with a reduced Mn content (Fe-0.18C-4.95Mn-0.4Si (wt.%)), nearly doubling the material's yield strength and successfully mitigating the presence of Lüders banding. It is interestingly found that Mn heterogeneity can not only directly stabilize austenite but also contributes to austenite stabilization via promoting carbon partitioning from the Mn-poor austenite into the Mn-enriched austenite. Heating rate is proven to be a key parameter to manipulate chemical heterogeneity, austenite stability and mechanical properties. The present strategy can be potentially applied to other advanced high strength steels.

Research on casing damage mechanism and prevention and control under creep behavior of salt-gypsum layer

As a good cap rock, the salt-gypsum layer often contains abundant oil and gas resources, but it has strong plastic flow and creep properties, resulting in frequent casing damage problems. Therefore, a new method is proposed to prevent and control casing failure in creep formation by using solid expandable tubular (SET). Based on the Heard model, the creep behavior of formation was described. The expansion experiment of the SET, the material tensile experiment of casing and SET with different expansion rates were carried out. The three-dimensional mechanical model and finite element model of casing-cement sheath- (SET) -formation were established. Numerical simulation of creep behavior of salt-gypsum layer under non-uniform in-situ stress was carried out. Comparative study of casing damage mechanism in two cases with or without SET prevention and control. The influence of sensitive factors such as SET wall thickness and expansion rate on the failure behavior of casing prevented and controlled by SET were analyzed. The results show that (1) In the direction of the maximum horizontal in-situ stress, the stress on the outer surface of the casing is large. In the direction of the minimum horizontal in-situ stress, the stress on the inner surface of the casing is the largest, and the material yield failure occurs first at this position of the casing. The compression deformation of casing is greater than the tensile deformation. The casing is oval after deformation. (2) By increasing steel grade and wall thickness of casing, the service time of the casing under creep behavior of salt-gypsum layer can be prolonged. However, while increasing cost and reducing diameter, it has not played a role in preventing casing failure. (3) By using the method of SET prevention and control, the casing stress is more evenly distributed, the maximum stress is effectively reduced, the stress growth rate is slowed down, and the external collapse resistance ability is significantly enhanced. The maximum stress of the casing is reduced by up to 24.96 %. The larger the wall thickness of the SET, the better the prevention and control effect, and the longer the service time of the casing. The increase of the ultimate wall thickness of the SET with high expansion rate can effectively make up for its poor prevention and control effect. (4) The new method of adding the SET between salt-gypsum layer and cement sheath has the advantages of increasing casing inner diameter, optimizing wellbore structure, reducing cost and wellbore risk. The research results can provide some reference value for the prevention and control of casing failure in creep salt-gypsum layer.

Influence of sowing dates on the phenological development and yield of medicinal crops in Transbaikalia

The results of field and laboratory studies for 2020, 2022 on the creation of agrophytocenosis of valuable and promising medicinal plants: milk thistle (Silybum marianum), common fennel (Foeni culum vulgare) and scorzonera (Scorzonera hispanica L.) are presented. The studies were carried out on meadow-chernozem mealy carbonate soil (light loam by granulometric composition) in the experimental field at different sowing dates in the conditions of the forest-steppe zone of Transbaikalia. The work is devoted to the study of the sowing dates influence (II ten-day period of May, II ten-day period of June, II ten-day period of July) on the duration of the interphase periods of plant development, linear growth, foliage, field germination, plant safety and yield of medicinal raw materials. The possibility of formation of different yields of medicinal crops due to different sowing dates has been established. The highest yield of medicinal raw material was formed in the crops of May 15 and June 15. Milk thistle had the yield of the herbage of 15.4–16.0 t/ha, dry mass – 2.46–2.56 t/ha, seeds – 1.69–1.71 t/ha; common fennel herbage – 43.0–43.2 t/ha, dry mass – 6.66–6.71 t/ha; scorzonera – with wet weight of root crops – 32.1 t/ha, leaves – 10.7 t/ha. Plant height by the time of harvesting of milk thistle was 163–166 cm and 54–57%; common fennel – 144–147 cm and 50–54%; scorzonera – 39 cm and 98%, respectively. There was no infestation of medicinal plants by diseases and pests. All crops were resistant to lodging and drought (5 points) in the conditions of Transbaikalia.

Research on Material Selection Method and Brittle Fracture Mechanism of High-Pressure Pipeline

Aiming at the problem of the brittle fracture of pressure pipeline, the elastic constraint structure is described by using members and engineering building structures, and the concept of elastic constraint is proposed. Through the stress field analysis of the pressure pipeline under internal pressure, it is found that the pressure pipeline under internal pressure is an elastic constraint structure. The elastic constraint effect is applied to the pressure pipeline to explore the influence of elastic constraint effect on the brittle fracture of pressure pipeline. The critical wall thickness and limit load of different materials are calculated by the limit bearing formula. Through simulation analysis of materials with different yield ratios and pipelines with different wall thicknesses of the same material (yield ratio is the ratio of yield strength to tensile strength), it was found that pressure pipelines made of the same material have an increased load-bearing capacity as the wall thickness increases, but their own elastic constraint effects are becoming more obvious, and the probability of the brittle fracture of the pipeline is higher. When the wall thickness of pressure pipelines made of materials with different yield ratios is certain, the lower the yield ratio is, the more likely the pipeline is to generate plastic deformation and the larger the deformation capacity is; the higher the yield ratio, the poorer the plastic deformation capacity of the pipeline and the smaller the deformation capacity. Pipelines with large yield ratio are more sensitive to the brittle fracture than those with small yield ratio.

A method for evaluating spectral down-shifting materials applied to solar cells

Spectral down-shifting materials convert the photons in the solar spectrum that are less efficiently utilized into photons that can be fully used by solar cells, providing an attractive idea for improving the photoelectric conversion efficiency (PCE) of the solar cells. However, there is currently no parameter that can reliably assess the photoelectric excitation effect of the down-shifting materials on solar cells. Here, a calculation method that can reliably evaluate the photoelectric excitation effect of the down-shifting materials on the solar cells is proposed, which introduces the solar spectrum, the quantum yield of materials, and the external quantum efficiency of the solar cells. Then, the calculation method is described in detail with the relevant physical processes, taking the down-shifting materials acting on crystalline silicon solar cells as an example. Finally, the Pearson correlation coefficient between the parametric photoelectric excitation efficiency (PEE) calculated using the method and the ΔPCE value obtained experimentally was 0.999 51, demonstrating the reliability of the calculation method. The PEE calculated using this method is an inherent property of the down-shifting material for a specific solar cell and does not change with external conditions. Therefore, PEE can be used as a parameter for down-shifting materials to facilitate the selection of materials with better effects on solar cells from an enormous number of down-shifting materials and is suitable for various types of solar cells.

The correlation between static strength and fatigue strength test and simulation

In the bogie, the frame plays a vital role. It is not only the installation foundation and direct bearing structure of other components but also can transmit the excitation load from all directions. Therefore, the rationality and reliability of the frame design are particularly critical. In this work, according to EN13749, UIC615-4, JIS E 4207, and JIS E 4208 standards, the load conditions are compiled, and the finite element analysis is carried out. The static strength and fatigue strength are tested on the test bench. The results show that the static strength results of the bogie frame are less than the allowable stress of the corresponding material. The fatigue assessment was carried out by Goodman diagram, and the data all fell within the envelope, which met the requirements of fatigue assessment. Finally, the test results are compared with the simulation results. Through the correlation analysis of the static strength test results and the finite element simulation results of the frame, the stress exceeds 10% of the material yield limit under the exceptional load condition, and the large stress points of the local hanger are compared. The results show that the frame strength test results and the finite element simulation results maintain a good correlation.

Using phase change material to reduce the loss of quantum yield of fluorescent polymer when exposed to high temperature

The quantum yields (QYs) of fluorescent materials decrease significantly as temperature rises, and this loss of QYs will become irreversible when exposed to high temperature for a long time. Herein, we prepare a zinc polyacrylate (ZnPA)/polyethylene glycol (PEG) composite using PEG-20000 as the phase change material (PCM) to reduce the loss of the QY of fluorescent ZnPA when exposed to high temperature. This composite is also a PEG-based form-stable PCM that is in solid state at 90 °C, solving the leakage issue of pure PEG in the melting process. Most important, the QY of ZnPA decreases by 50.4 % after a long period of thermal cycling, while that of the ZnPA/PEG composite does not decrease at all. This comparison indicates PEG-20000 can greatly reduce the loss of the QY of ZnPA when exposed to high temperature, in virtue of its excellent thermal energy storage density and negligible temperature change in the phase change procedures, as well as the rapid heat transfer between PEG-20000 and ZnPA.

Metabolome and transcriptome analyses provide new insights into the mechanisms underlying the enhancement of medicinal component content in the roots of Acanthopanax senticosus (Rupr. et Maxim.) Harms through foliar application of zinc fertilizer.

Acanthopanax senticosus (Rupr. et Maxim.) Harms is a perennial shrub of the Acanthopanax genus in the Araliaceae family and has a high medicinal value. The application of zinc fertilizer can improve the yield and quality of medicinal materials. However, there are limited reports on approaches to increase the content of medicinal components in A. senticosus, hindering the improvement of its medicinal quality. In this study, A. senticosus was treated with 0.1% (LZn) and 0.4% (HZn) zinc sprayed on the leaf surface. The effects of zinc treatment on the medicinal components in the roots of A. senticosus were analyzed by comprehensive metabolomics and transcriptomics analyses. A total of 316 metabolites were detected, with a prevailing occurrence of terpenoids and phenylpropanoids. We identified metabolites related to the medicinal components that were upregulated after Zn treatment, including 43 terpenoids, 19 phenylpropanoids, eight phenols, and three flavonoids. Combining differential gene expression and K-means analysis, we found 95, 65, and 25 upregulated genes related to phenylpropanoid biosynthesis, terpenoid biosynthesis, and flavonoid biosynthesis, respectively. Under different concentrations of Zn treatment, the upregulated metabolite biosynthesis-related genes and differentially expressed transcription factors varied. Pearson correlation network analysis revealed significant correlations among terpenoids, phenylpropanoids, flavonoids biosynthetic genes, and several transcription factors (ERFs, WRKYs, bHLHs, NACs, and MYBs). This study lays the foundation for understanding the metabolic processes in response to varying levels of zinc foliar spray and provides a theoretical basis for enhancing the efficiency of zinc fertilizer utilization in A. senticosus.

A New Regression Model for the Prediction of the Stress-Strain Relations of Different Materials.

Experimental flow stress-strain data under different stress states are often used to calibrate the plastic constitutive model of anisotropic metal materials or identify the appropriate model that is able to reproduce their plastic deformation behavior. Since the experimental stress-strain data are discrete, they need to be mathematically returned to a continuous function to be used to describe an equivalent hardening increment. However, the regression results obtained using existing regression models are not always accurate, especially for stress-strain curves under biaxial stress loading conditions. Therefore, a new regression model is proposed in this paper. The highest-order term in the recommended form of the new model is quadratic, so the functional relationships between stress-strain components can be organized into explicit expressions. All the experimental data of the uniform deformation stage can be substituted into the new model to reasonably reproduce the biaxial experimental stress-strain data. The regression results of experimental data show that the regression accuracy of the new model is greatly improved, and the residual square sum SSE of the regression curves of the new model reduced to less than 50% of the existing three models. The regression results of stress-strain curves show significant differences in describing the yield and plastic flow characteristics of anisotropic metal materials, indicating that accurate regression results are crucial for accurately describing the anisotropic yielding and plastic flow behaviors of anisotropic metal materials.

A semi-analytical model to predict residual stress distribution in thick wall girth weld with narrow gap welding

Benefited by its high efficiency and low cost, the narrow gap welding has been widely used in thick wall pressure equipment. Considering the fact that defects in welded joints inevitable, the safety assessments for welding equipment with residual stress are crucial. However, for the thick-wall equipment using narrow-gap welding, the current safety assessment standards specifying the residual stress distribution are not detailed or missing. In this paper, the through-wall residual stress of thick wall girth welds with narrow gap welding is studied. The stress components (bending stress, membrane stress and self-equilibrating stress) at the evaluation point are obtained by stress decomposition. The effects of the heat input, the wall thickness, the radius thickness ratio and the number of welding passes on residual stress are considered, respectively. The results show that the heat input only affects the distribution of bending stress and membrane stress. The axial and hoop bending stresses decrease with the increase of the wall thickness, and the hoop membrane stress is about 0.75 times material yield strength. With the increase of radius thickness ratio, the bending stress decreases while the hoop membrane stress increases. The stress distribution is fluctuating when the number of welding layers is small, which be expressed by trigonometric function. The distribution model of welding residual stress through the wall thickness is proposed. The stress distribution obtained by the proposed prediction model is in good agreement with the finite element calculation results.

MORPHOLOGICAL FEATURES AND PRODUCTIVITY OF THE ATROPA L. GENUS SPECIES, CULTIVATED IN THE MOSCOW REGION

Background. The application of the anatomical method of studying various forms, varieties and species will allow to determine the degree of plant adaptation to habitat conditions and to assess its ecological plasticity.
 Purpose. This work aim is to evaluate the species and breeding samples of the Atropa genus by a set of signs, including morphological description, shape, size and weight of leaves, the nature of the pubescence of the leaf plade epidermis, location, size and number of stomata, as well as the yield of raw materials.
 Results. All collection samples of the studied species of the genus Atropa in the conditions of the Non-Chernozem zone of the Russian Federation undergo a full cycle of development. The assessment of the potential resistance of 14 forms and species of belladonna to unfavorable biotic and abiotic environmental factors was carried out, their main morpho-anatomical features were studied. The adaptive potential of the leaves of the studied Atropa plants is due to the variability of the structural elements of the leaf epidermis and is one of the factors of resistance to stress. In the group of studied samples, A. acuminata (406, Lithuania) and A. belladonna (487, Poland) have the lowest stress-adaptive potential (according to the set of signs). It was noted that populations of A. belladonna from Eastern Europe and France have signs of xeromorphism against the background of a decrease in plant size compared to the control and the lowest yield. It is noted that A. belladonna samples from Europe with yellow corolla staining occupy an intermediate value in yield in the presence of xeromorphic signs, which indicates their adaptability to the conditions of agrocenosis. The presence of numerous secreting trichomes in the studied accessions of A. belladonna and A. komarovii (nos. 5 and 14) may indicate their potential resistance to diseases and pests. The A. caucasica and A. komarovii species, as well as the A. belladonna specimen from Great Britain (no. 1), can be considered well adapted.
 Conclusion. The highest-yielding populations are from Russia A. belladonna 15/15; A. caucasica 118 compared to the Bagira variety. These samples can be considered promising and well-adapted candidates for creating a new variety of A. belladonna.

Биоэнергетические и репродукционные насаждения настоящих тополей в Центральном Черноземье России

The need to use fast-growing tree for bioenergy production was noted in the international and domestic press in the second half of the 20th century. In the first twenty years of the current century in a number of countries this problem has not only acquired research character, but also found a practical solution. The results of the research of true poplars (black, balsamic and their hybrids) on newly established field experiments in the Central Black Earth Region of the Russian Federation are considered. The aim of the research is to study and select promising forms of true poplars. Two types of experimental plots were established: variety testing plots and collection-stool bed plantations for reproduction of promising clones and varieties. The rooting ability, safety and growth in height were monitored on variety testing plots, and the yield of planting material (stem cuttings) was determined on reproductive collection-stool bed plantations. The best results on growth were noted on 2-year variety testing site facilities of LLC "United Nurseries" and carbon polygon of Voronezh State Forestry University named after G.F. Morozov in Voronezh region. Several fast-growing clones and varieties of true poplars at juvenile age were identified here. Among them we can mention P. trichocarpa No. 84, euramerican cultivar Sacrau-59, hybrids E.s.-38, and Version. Their average heights ranged from 359±21.5 to 416±12.7 cm, and maximum heights ranged from 435 to 495 cm. The best results in growing reproductive material were obtained at the collection-stool bed plantation of the Kulikovsky Forestry of the Lipetsk Forestry Department. Among annual plants the best growth results were found in the poplars trichocarpa No. 84 (183 cm), deltoides (149 cm), Marylandica (147 cm), simonii (133 cm) and E.s.-38 (157 cm). Among the annual shoots grown on three-year-old roots, Sacrau-59 (340 cm), E.s.-38 and deltoides (240 cm each), Marilandica' (230 cm) and Version (200 cm) were superior to the others in height. In general, the yield of standard stem cuttings from annual plants on 1-year-old roots was about 16 thousand pieces/ha and from annual plants on 3-year-old roots – 78 460 pieces/ ha. The clones and varieties mentioned above can be recommended for creation of bioenergy plantations in the Central Black Earth region of the Russian Federation. The first obtained results of these studies are promising in terms of rational use of renewable energy resources in Russia. For citation: Tsarev A.P., Tsareva R.P., Tsarev V.A., Evlakov P.M. Bioenergetic and Reproductive Plantations of True Poplars Species in the Central Black Earth Region of Russia. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 5, pp. 75–89. (In Russ.). https://doi.org/10.37482/0536-1036-2023-5-75-89

Activated char from the co-pyrolysis of polystyrene and olive stone mixtures for the adsorption of CO2

Yogurt plastic containers made of polystyrene (PS), olive stone, and mixtures of both have been converted into activated carbon materials transforming them firstly into char via pyrolysis and secondly with activation using either KOH or H2SO4. The pyrolysis of the olive stone gave a higher yield of material than the plastic PS. However, the activation of the PS char with KOH was more effective, reaching surface areas of 508 vs 194 m2 g−1 of the corresponding prepared with olive stone. The prepared materials were tested as CO2 adsorbent in thermobalance and fixed-be column assays. The materials activated with H2SO4 slightly enhanced the adsorption ability of the original char but were far from the performance obtained with KOH activation. The CO2 isotherms showed high synergy of CO2 uptake and selectivity when using activated chars prepared with the char from the mixture of raw materials, specially at a 1:1 mass ratio. The isosteric heat of adsorption values were those expected for a physisorption process. Further experiments in a fixed-bed column were also studied at atmospheric pressure at different inlet CO2 concentrations (10–50%). The CO2 retention increased as the partial CO2 pressure rose. Besides, a very similar performance of the material prepared with plastic and olive stones was obtained at 50%, i.e. 220 and 197 mg g−1 respectively. At low CO2 concentrations, the materials enriched with plastic displayed better performance than those prepared with olive stone. Cycles of adsorption-desorption were carried out in the column to assess the stability of the materials. The curves obtained did not display any substantial change, demonstrating the lack of adsorption retention.

A biotechnological method for silkworm sex regulation

Abstract The aim of this work is to use the biotechnological method of silkworm sex regulation as a breeding method. For this purpose, butterflies were mated immediately after their emergence in a chamber with a constant magnetic field for 4 h. By studying the natural fertilization of the Sheki-2 silkworm in a constant magnetic field, it was possible to change the natural sex ratio of the offspring from 1:1 to 1:3 in favour of males. A direct positive correlation was observed between the magnetic field strength and an increase in the number of males in the offspring, with the maximum number of males observed at a strength of 729.7 kA/m. The developed mathematical model made it possible to calculate the activation coefficient of magnetic fields influencing the cytogenetic process in the silkworm, which was 4.02 × 10−3 kA/m. An attempt was also made to explain the mechanism behind the cytogenetic influence of a constant magnetic field on possible options for obtaining males during the natural fertilization of silkworm females. Implementation of the developed method in the breeding programme will enhance both the quantity and quality of silkworm productivity. This is achieved by increasing silk yield and improvement of the raw materials obtained from the males. If these positive outcomes are consistently observed in other silkworm breeds, this method has the potential to become widely adopted for large-scale breeding of the entire silkworm population in the country.

Effect of potassium in catalysts obtained by the solution combustion synthesis for co-production of hydrogen and carbon nanofibers by catalytic decomposition of methane

A set of catalysts containing 0.25–10 wt% K2O was prepared by solution combustion synthesis. The catalytic systems were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and low-temperature nitrogen adsorption. The catalytic methane decomposition was carried out at 0.5 MPa, 100 LCH4/(h·gcat), and temperature ranging from 550 to 750 °C. It has been found that varying the potassium content led to a change in the phase composition and textural characteristics of the resulting catalysts. The introduction of potassium (0.25 wt% K2O) into the nickel catalyst made it possible to change the particle size distribution towards the formation of smaller particles, from 5 to 30 nm to 5–10 nm, promoting the formation of higher yield of H2. The Ni-0.25 %K2O/Al2O3 и Ni-1 %K2O/Al2O3 catalysts demonstrated the highest hydrogen yield of 11.6 g/gcat and 17.0 g/gcat with a maximum at 675 and 750 °C, respectively. The highest yield of carbon material (51.0 g/gcat) was obtained over Ni-1 %K2O/Al2O3 catalyst.

Process Development of Screen-Printed Magnetic Sheets for Electric Machines via Statistical Design of Experiments

Electrical machines play a major role in achieving a more sustainable economy by driving the further electrification of industry and transportation. To enhance the electric motor productivity during production and the efficiency during operation, it is essential to maximize the material yield rate during the production of stator and rotor sheet stacks and reduce iron losses during operation. Screen-printing technology can help to achieve these goals by producing thin magnetic sheet laminations in near-net-shape geometry, resulting in minimum material waste during production. Moreover, reducing the sheet thickness decreases the eddy current losses and avoids mechanical stress during manufacturing, leading to improved motor efficiency. Additionally, screen printing facilitates the production of multi-material components and variable alloy compositions. This study aims to identify the relevant factors and printing parameters so that screen-printed magnetic sheets can achieve product specifications. A method involving the statistical design of experiments is performed in several iterations to investigate the target parameters of the print cycle time, green part weight, shape integrity and layer thickness, and to analyze the main interdependencies. The results of this study provide valuable insights into optimizing the screen-printing process for soft magnetic sheets, enabling the production of efficient electric motors while reducing material scrap.