High Silicon Content Research Articles

Investigation of phase transformation and mechanical properties of silicon addition on AlCrFeMnNi high entropy alloys

Abstract This paper examines the impact of silicon in the AlCrFeMnNi high-entropy alloy system, focusing on both its microstructural and mechanical properties. Alloys with varying silicon content (x = 0, 0.3, 0.6, 0.9 atomic ratio) were synthesized using vacuum arc melting. The phase formation of these high-entropy alloys was analyzed using X-ray diffraction to comprehend the alloying process behaviour. The findings revealed that the solidification of the AlCrFeMnNi alloy occurred in dendritically, with dendrite cores containing Cr, Fe, and Ni, while interdendritic regions were enriched in Al and Ni after adding Silicon. Increasing the silicon content from 0 to 0.9 led to significant improvements in microhardness and wear resistance. This improvement is attributed to the reinforcement of grain boundaries provided by silicon. The formation of an Al and Ni rich B2 phase is crucial in resisting dislocation motion and preventing further deformation. Additionally, the addition of silicon led to improved corrosion resistance, as demonstrated by potentiodynamic polarization measurements. However, a trade-off was observed between compressive strength and ductility: compressive strength increased with higher silicon concentrations, but at the expense of ductility.

Laser beam welding of T joints for aluminum–Copper–lithium aircraft panels: Effect of filler wire on recyclability and weldability

This study assessed the weldability and recyclability of four filler wires, two commercial (ER4047 and ER2319) and two experimental (ER2395 and J300), for laser beam welding of aluminum-Copper-lithium (Al–Cu–Li) aircraft panels. The results showed key differences in porosity and crack formation. The ER2319 filler exhibited a higher tendency for wormhole-type porosity compared to the others, which had similar pore area fractions. ER2395 displayed the longest crack length, likely due to its high lithium content. Chemical compatibility with the Al–Cu–Li base alloy AA2198 was confirmed for the ER2319, ER2395, and J300 filler wires, enabling 100% closed-loop recyclability without disassembly or alloy sorting. However, the high silicon content (around 11%) of ER4047 resulted in a recycled alloy that exceeded the allowable Si limit for AA2198, making it unsuitable for closed-loop recycling. Several end-of-life (EoL) strategies were explored for scrap fractions from ER4047-welded coupons. The 0C and 1C cutting strategies yielded hybrid fractions incompatible with AA2198 but suitable for the more Si-tolerant AA2196 alloy. The 3C strategy, involving weld seam separation before remelting, optimized recycling rates and minimized environmental impact. Additionally, a pre-scrap characterization method was developed to analyze weld seam composition, allowing for the prediction of recyclability issues and filler wire mass estimation in coupons where both the skin and stringer were made of the same alloy. This method provides a practical approach for evaluating welded structures in future recycling efforts.

Incorporating geranium plant waste into ultra-high performance concrete prepared with crumb rubber as fine aggregate in the presence of polypropylene fibers

Abstract This research examines the efficiency of ultra-high-performance concrete (UHPC) when utilizing geranium plant (GP) ash, which is subjected to different curing temperatures ranging from 300 to 900°C for 3 h of burning time. The GP ash is used as a replacement for cement in varying amounts (10, 20, 30, 40, and 50 wt%). Crumb rubber powder is utilized as a substitute for fine aggregate. Polypropylene fibers have been used to improve concrete performance. The performance of UHPC is evaluated by assessing its mechanical qualities, such as flexural strength, splitting tensile strength, and compressive strength. The sorptivity test is also evaluated as a component of it. Scanning electron microscopy is used to analyze UHPC after exposure to temperatures as high as 900°C. The findings demonstrated a notable enhancement in the mechanical characteristics of all mixtures. The most favorable mixtures were achieved with proportions of 50, 40, 40, and 20% for mixtures including GP waste incinerated at temperatures ranging from 300 to 900°C. Furthermore, the optimal outcome is achieved when 40% substitution is performed at a temperature of 700°C, resulting in notable enhancements of 14% in compressive strength, 30% in flexural strength, and 17% splitting tensile strength, respectively. At a high temperature of 700°C, the decrease in strength increased to approximately 37–40% as a result of the initial removal of carbon dioxide from calcite at temperatures ranging from 600 to 900°C and reached 56% at 900°C. Great resistance to sorptivity, as well as a dense and compact microstructure with a high content of calcium and silicon, was obtained.

Synthesis of Sustainable Binary Calcium Monosilicate Ceramics from Bio-waste: Effect of Sintering Temperature on Microstructure and Electrical Properties

This study was conducted to synthesise calcium monosilicate ceramics using rice husks and raw eggshells and investigated the effect of sintering temperature on the physical,microstructure and electrical properties of the final product. The high content of calcium and silicon in eggshells and rice husks, respectively promote the use of waste materials in the production of calcium monosilicates by mixing in a molar ratio 1CaO:1SiO2 and fired at different sintering temperatures for 2 hours with a heating rate of 10°C/min. A good correlation between sintering temperature, structural, microstructure, and electrical properties of calcium silicate was observed. The structural and morphological evolutions were characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with electron dispersive X-ray analysis (EDX). XRD analysis showed that the main crystalline phases of synthesised calcium monosilicate are pseudowollastonite (ICSD 98-005-2598) at 1250°C, and the phases of SiO2 also exist in different types of minerals. Besides, a small amount of larnite, Ca2SiO4 was traced at 1100°C and 1200°C. Fourier Transforms Infrared (FTIR) spectra showed the presence of characteristic functional groups in the precursor powder. In Nyquist plots, the summit frequency of the dominant arc decreases with increasing sintering temperatures. It may be attributed to the co-effect of the grain size and pore. A larger value of impedance at a lower frequency suggests an essential role of boundaries in governing the electrical properties of the sintered ceramics. As the sintering temperature increases, the microstructure of the sintered samples becomes denser while conductivity performance decreases. This is due to the reduction of particle interfaces and charge transfer.

Оценка влияния вредных факторов производственной среды в литейном цехе

Harmful factors in the working area of foundry operators are considered. The complexity of workflows affects the quality of air in the foundry. The casting process is accompanied by the generation of a significant amount of dust as well as high levels of noise and vibration. The relevant aspect of the study is the assessment of the state of occupational safety, considering the harmful factors at the production in question. Dust content has been thoroughly investigated by dispersive and elemental analysis of dust using X-ray fluorescence analysis and laser diffraction. The impact of the vibroacoustic factor has been studied. An analysis of the sound pressure level in the working areas of the foundry has been provided. The authors have proposed technical measures to reduce dust content and the level of impact of the vibroacoustic factor. The development of a system of measures to minimize harmful impact has been based on a combined analysis of factors. Methods to reduce noise and dust content at workplaces are proposed as follows: organizing a highly efficient system of post-treatment of dust emissions, increasing equipment sound absorption, installing structures to reduce noise pollution, and using a coating system made of dense rubber structures (compounds). Ensuring safe working conditions in working areas of the foundry has been studied; the improvement of working conditions due to the improvement of existing and installation of new noise and vibration protection means has been proposed. An integrated approach to the assessment of production factors has been provided, which has been the key element for the development of engineering and organizational protection measures. The integrated analysis helped identify the degree of impact of harmful factors such as noise, and dust content on machine operators during the casting process and to conduct a comparative assessment of sound pressure levels. The sound pressure can be reduced by 8–10 dB using improved mechanisms of shot-blasting chamber operator protection. More extensive dust protection measures are proposed due to the sample content of 85% of the dust mass less than 100 microns and multicomponent dust with a high content of silicon and iron. The findings provide a technical value for the substantiation of the modernization of noise and dust reduction systems at foundry operator workplaces.

PhytOC sequestration characteristics and phytolith carbon sink capacity of the karst grasslands in southwest China

Grassland is an important component of terrestrial ecosystems and plays a crucial role in the global carbon cycle. PhytOC (phytolith-occluded organic carbon) is an extremely important long-term and stable carbon pool in terrestrial ecosystems. Southwest China karst soil exhibits obvious characteristics of alkalinity, high silicon content, and rich calcium, which can significantly influence the characteristics and mechanisms of PhytOC sequestration in vegetation. To elucidate the sequestration characteristics and mechanisms of PhytOC in the karst grasslands, three typical karst grasslands of tropical shrub tussock (TST), warm-temperate shrub tussock (WST), and mountain meadow (MM) from Guizhou province of southwest China were studied. The following results and conclusions were obtained that: 1) the range of PhytOC content of aboveground plant parts, underground roots, and soil in the karst grasslands was 4.03–16.54 g·kg−1, 10.67–33.92 g·kg−1, and 0.63–1.89 g·kg−1, respectively. The underground roots are an important site for phytolith carbon sequestration in grassland ecosystems, and the PhytOC content of underground roots may be higher than that of the aboveground parts. 2) The PhytOC sequestration rate of vegetation was 7.34–15.93 kg·ha−1·yr−1, and the annual sequestration amount of PhytOC of the whole grasslands in southwest China could reach 0.48 × 103–1.48 × 103 t CO2. Compared to grasslands in non-karst regions of China, karst grasslands in southwest China have a higher sequestration rate of PhytOC in vegetation and a greater capacity for phytolith carbon sequestration. 3) Soil available silicon, pH, and stoichiometric characteristics of C, N and P nutrients significantly affected the phytolith carbon sequestration of vegetation and the soil accumulation of PhytOC in the karst grasslands. The research results are of great significance for estimating the phytolith carbon sequestration capacity of grassland ecosystems and for grassland construction and management based on enhancing carbon sequestration.

Petrogenesis and tectonic setting of granitic pegmatites in the Beishan orogenic Belt, Northwest China: Evidence from geology, geochronology and geochemistry

The Weiboshan (Li-, Cs- and Ta-enriched) LCT-type Nb–Ta deposit located in Ejin Banner, Inner Mongolia, represents a newly discovered pegmatite-type rare metal deposit of significant interest. In this paper, we describe the petrography and present new mineralogical and whole-rock geochemical data and zircon U–Pb ages of ore-related granitic pegmatites in this deposit. Pegmatite dikes can be divided into three distinct zones on the basis of their contents: the K-feldspar graphic granite pegmatite zone (Kf), microcline graphic granite pegmatite zone (Mic), and albite–muscovite granite pegmatite zone (Ab). The pegmatite dikes and associated mineralization formed during the Mesozoic. Granite pegmatites in various zones display distinctive geochemical features characterized by high silicon contents, substantial alkali enrichment, and relatively low iron, calcium, and magnesium levels. These pegmatites are classified as peraluminous or quasialuminous and exhibit low total rare earth element concentrations. Notably, these pegmatites are enriched in large ion lithophile elements (LILEs), such as Rb, K, and U, but depleted in high field strength elements (HFSEs), such as P and Ti. The progression from the Kf to Mic to Ab zones signifies the thorough evolution of the granitic magma, where the late-stage near-hydrothermal system assumed a crucial role in the mineralization of rare metals during magma differentiation. The Weiboshan pegmatites, which exhibit syncollisional attributes, are A-type granites formed through crustal partial melting induced by decompression. This process occurred against the background of postorogenic extension driven by asthenospheric mantle upwelling resulting from lithospheric delamination due to crustal collision and thickening.

SYNTHESIZING OF AN ALUMINUM ALLOY RICH IN IRON AND SILICON BY SURFACING WITH A CONSUMABLE ELECTRODE

Developing lightweight, high-strength materials is an important technological problem of the present decade. However, alloying with expensive elements is mainly used to increase the strength of structural materials. In contrast, aluminum alloys with a specific ratio of silicon and iron show very high mechanical properties. This work aims to develop a technology for synthesizing an aluminium-based alloy with a high content of iron and silicon, consisting mainly of intermetallic phases and having high strength and hardness. The additive technology method of surfacing with a consumable electrode produced the alloy. The ratio of the initial components, meticulously determined, led to the precise chemical composition of the alloy. As a result of the synthesis, an ingot with a uniform microstructure and insignificant porosity, a testament to the careful process, was obtained. At room temperature, the alloy has a phase composition of 42.6% β-phase, 43.4% θ-phase and 13.5% FCC-phase. Phases β and θ are large particles between which the FCC aluminum phase is located. The hardness of the intermetallic β/θ is 450.8±5 HV1, FCC aluminum has a hardness of 92.5 HV1. This research has the potential to inspire further developments in materials science and engineering.

Waste Symbiosis through the Synthesis of Highly Crystalline LTA and SOD Zeolites.

In recent years, the demand for natural and synthetic zeolites has surged due to their distinctive properties and myriad industrial applications. This research aims to synthesise crystalline zeolites by co-recycling two industrial wastes: salt slag (SS) and rice husk ash (RHA). Salt slag, a problematic by-product of secondary aluminium smelting, is classified as hazardous waste due to its reactive and leachable nature, though it is rich in aluminium. Conversely, RHA, an abundant and cost-effective by-product of the agro-food sector, boasts a high silicon content. These wastes were utilised as aluminium and silicon sources for synthesising various zeolites. This study examined the effects of temperature, ageing time, and sodium concentration on the formation of different zeolite phases and their crystallinity. Results indicated that increased Na+ concentration favoured sodalite (SOD) zeolite formation, whereas Linde type-A (LTA) zeolite formation was promoted at higher temperatures and extended ageing times. The formation range of the different zeolites was defined and supported by crystallographic, microstructural, and morphological analyses. Additionally, the thermal behaviour of the zeolites was investigated. This work underscores the potential to transform industrial waste, including hazardous materials like salt slag, into sustainable, high-value materials, fostering efficient waste co-recycling and promoting clean, sustainable industrial production through cross-sectoral industrial symbiosis.

Consecutive covalent bonds reconstruct robust dual-interfaces by carbonized binder to enable conductive-additive-free durable silicon anode

The substantial volume expansion and poor electrical conductivity tremendously hinder the utilization of high silicon (Si) content anode with compelling capacity. Herein, we propose an efficient strategy to stabilize Si-based anodes by carbonization of the slurry-casting Si electrode with a conductive polyoxadiazole (POD) binder. Such POD-derived materials can form a nitrogen/sulfur-rich carbon network, not only serving as a resilient scaffold to buffer the volume swelling and firmly adhere the Si to the current collector by robust dual-interfaces bonding but also evolving into a conductive matrix to facilitate the electron/ion transport. The conductive-additive-free Si electrode possesses a high Si content of up to 84 %. It exhibits a high initial Coulombic efficiency (86.34 %), competitive gravimetric capacity (3340 mAh g−1), stable cycling performance (the capacity retention rate reaches 79 % after 1000 cycles), commercial-level areal capacity (5.32 mAh cm−2), and outstanding rate capability (1673 mAh g−1 at 5.0 A g−1). This work offers a scalable modification idea and forward-looking perspective for high-performance Si-based anodes in next-generation lithium-ion batteries.

Quantifying the biogenic silica production of picoplankton in the oligotrophic ocean: A case study in the South China Sea

Silicon (Si) utilization is not limited to eukaryotes. Recent research has suggested that the pattern of a large contribution of picocyanobacteria to biogenic silica (bSi) stocks might be widespread in the oligotrophic open ocean. We are the first to measure the size-fractionated bSi standing stocks and production rates in the oligotrophic South China Sea (SCS), which has obvious characteristics of oligotrophic waters. The 150 m integrated bSi standing stocks in the pico-sized fractions averaged 23 % of the total; the contribution of picoplankton to the total bSi production rate was 44 %. Interestingly, our estimated contributions of Synechococcus alone to the <2 μm bSi standing stock and < 2 μm bSi production rates averaged 14 % and 66 %, respectively, indicating that the significant and persistent contribution of bSi was strongly associated with marine picocyanobacteria. Furthermore, the dynamic changes in nutrient concentrations, especially in DIN and DIP, also potentially affected the variability in picoplankton bSi stocks and production rates, while the effects of temperature and salinity were not obvious. In this study, we have provided new information on measurable bSi in the picoplankton size fraction and its production rate in the SCS. We have demonstrated that picoplankton contributes a measurable, and at times significant, proportion to both the total bSi standing stock and its production rate in the SCS. A high silicon content within picocyanobacteria has important implications for understanding both their ecology and their contribution to biogeochemistry.

Mesoporous Silica with an Alveolar Construction Obtained by Eco-Friendly Treatment of Rice Husks.

The high silicon content in rice plant waste, specifically rice husks, makes this waste by-product attractive for the extraction and valorization of silicon oxide, which is widely used as an inert support in catalysis, drug delivery and molecular sieving. The procedures currently used for the treatment of plant biomass make extensive use of mineral acids (HCl, H2SO4, HNO3), which, besides them being potential environmental pollutants, reduce the yield and worsen the chemical-physical properties of the product. In this study, an evaluation of the easy treatment of rice husks by benchmarking different, more eco-friendly carboxylic acids in order to obtain a mesoporous SiO2 with an alveolar structure and a relatively high surface area and pore volume (300-420 m2/g, 0.37-0.46 cm3/g) is presented. The obtained mesoporous silicas are characterized by worm-like pores with a narrow size distribution and a maximum in the range of 3.4-3.5 nm. The mesoporous structure of the obtained materials was also confirmed by TEM. The complete removal of the organic part of the rice husks in the final materials was evidenced by thermogravimetric analysis. The high purity of the obtained mesoporous silica was detected using ICP analysis (98.8 wt. %). The structure peculiarities of the obtained mesoporous silicas were also characterized by solid-state NMR and ATR-FTIR spectroscopies. The morphology of the mesoporous silica was investigated by SEM.

In-situ formation and ablation mechanism of dense and multilayered ZrB2-ZrSi2-MoSi2 ultra-high temperature ceramic composite coating on Ta-W alloy under plasma blame beyond 2000 ℃

A dense and three-layered ZrB2-ZrSi2-MoSi2 composite coating with continuous interlayer interfaces and a thickness of ∼270 μm was in-situ prepared on Ta-10 W alloy by plasma spraying and pack cementation. Subjected to plasma ablation at 9.8 MW/m² for 1000 seconds, the coating with a mass ablation rate of 0.0002 mg/s undergoes oxidation to form a skeleton-structured ZrO2 and liquid self-sealing SiO2. During the ablation, the over-diffused silicon top layer of the coating with high silicon content and uniform phase distribution can produce relatively adequate SiO2 to withstand the consumption for up to 1000 seconds, yielding excellent ablation resistance above 2000 ℃.

EXPERIMENTAL DETERMINATION OF TORQUE FOR THE DRILLING OFAL7SIMG ALLOY

The productivity of a machining process is closely related to the value of the cutting force.For the calculation of the cutting forces, a series of models have been developed to allow the determination of these forces according to the machined material and the specific conditions in which the process is carried out. Usually, for a better approximation of the value of the cutting force, the unitary specific cutting force is used, which depends on the machined material. For common materials, the values of specific unitary cutting forces are presented in the specialized literature, but for less frequently used materials, for example, those with reduced machining properties, the respective values are difficult, sometimes impossible to find. In this paper, determining the unitary specific cutting force for an aluminum alloy with a high silicon content is intended, recognized as difficult to machine. The determination of the value of this force is done starting from the measured values ofthe torsional moment at the drills.

Analysis of Morphological and Elemental Composition in Rice, Beans, and Groundnut Husk

The morphological characteristics and elemental composition of these agricultural products provides insights into their nutritional value, chemical properties, and potential industrial applications, contributing to advancements in food science, agriculture, and environmental sustainability. The comprehensive analysis of the morphological and elemental composition of three widely consumed agricultural products: rice, beans, and groundnut husk as a partial substitute for sand due to its high content of calcium, silicon, aluminum, iron, and other elements when properly controlled. Transforming them into practical materials in order to reduce their detrimental impact on the environment. An equal weight of 50 g of Rice husk, 25 g of bean husk, and 25 g of groundnut shell were measured out of 100 g of untreated samples and oven dried at 1000C for 4 hours. The samples were the crushed to fine particle and sieve, which was burned at a temperature of 5500C in an electric furnace for 4 hours. The result obtained microscopic techniques such as Scanning Electron Microscope (SEM) with Energy Disperse X-ray fluorescence (EDXRF) and X-ray diffraction (XRD), were used to observe the surface and element presence in RBGH. The result among other things shows that untreated RBGH atomic concentration of Si is 65.79%, K is 16.01.53%, P is 5.14% Ca is 3.36% and Mg is 3.35% respectively, and the SEM shows that it has a porous cellular structure and consists of irregular-shape particles. The findings shed light on the potential industrial applications of these agricultural byproducts

Preparation of high-density green body based on binder jetting 3D printing using spheroidized SiC powder

Silicon carbide (SiC) ceramic stands as a critical material in the realm of high-performance engineering ceramics. However, Crafting SiC ceramics with intricate structures and superior mechanical properties presents notable challenges in shaping, sintering, and processing. Binder jetting (BJ) additive manufacturing has the outstanding advantages of high forming efficiency and no thermal deformation, especially suitable for printing complex structure SiC components.; however, BJ printed green bodies often exhibit low density, resulting in high residual silicon content and diminished strength of the final components. In this work, we introduce a novel strategy to fabricate high-strength SiC components with complex geometries by improving the density of printed SiC green bodies. This method involves modifying the morphology of SiC powder through the molten salt method to increase the density of BJ 3D printed green bodies from 1.24 ± 0.13 g/cm³ to 2.01 ± 0.03 g/cm³, followed by a reactive melt infiltration process. The resulting RB-SiC ceramics display exceptional flexural strength, averaging 280.60 ± 33.05 MPa, and an elastic modulus of 294.67 ± 4.90 GPa. These values represent some of the highest for flexural strength and elastic modulus reported among 3D-printed SiC composites. With its robust mechanical performance and streamlined fabrication process, this strategy holds substantial promise for the production of structural SiC ceramics.

Isothermal reduction and comparative analysis of reaction kinetics of sponge iron produced from hematite-charcoal reaction using non-contact direct reduction method

The challenge of making sponge iron, or direct reduced iron (DRI), is hard to overstate. These are a key feed for metallurgical operations while iron extraction sets these limits, which include scarcity of metallurgical coke, poor environmental impact, and high production cost. Thus, the non-contact direct reduction process of DRIs has the potential to significantly reduce carbon deposition and CO2 emission from the ironmaking process. This work produced sponge iron from commercially acquired hematite ore using an alternative reducing agent (i.e. charcoal) under specified isothermal conditions. Comparative analysis of reaction kinetics models including Ginstein−Brounshtein and Shrinking core models was also performed to ascertain the resistances that control the reaction rate for reduction degree up to 98.1%. The reduction kinetics were found to be described by reaction control time and activation energies based on a shrinking core model as the reduction time lasted for 120 min at temperatures 843–1273 K. At temperatures above 973–1073 K, the rate-limiting step was found to be solely an interfacial chemical reaction process, with an apparent activation energy of 196.1 kJ/mol. In addition, a slowing trend was observed for iron ore sample sizes 10–20 mm as a result of ash layer infiltration around the inner-core structure of the DRI metal matrix. The DRI morphological characteristics were performed using Scanning Electron Microscopy (SEM) and Electron Dispersive Spectrometry (EDS) to ascertain the mineralogical and morphological properties of the DRI samples. The XRF analysis confirms that the raw iron ore sample is hematite. Its iron content is 70.04% metallic iron (TFe) which has 83.59% Fe2O3 The SEM/EDS image also revealed the presence of micropores on the DRI morphology. This indicates that the reduction ratio and swelling extent rise with the temperature and time. This happens for all DRI sizes. However, the EDS result confirms the presence of gangue elements within the DRI metal matrix and mineralogical structure. The DRI contains very high silicon content up to 33.90%. So, a fluxing experiment is needed using limestone (CaCO3) or quicklime (CaO) quicklime to remove gangue (silicate, aluminate) from the DRI matrix. At the set reduction temperatures, the largest metallization degree of 93.05% at 1273 K for a reduction time of 120 min was achieved. This showed that the overall reduction process still follows the expected chronological order since the NDR process uses CO gas from preheated charcoal. This makes DRI be produced from raw hematite under non-contact reduction bases. Therefore, the NDR technique offers a viable option for sponge iron production in modern-day iron and steelmaking processes.

Exploring the potential of nitrophosphogypsum and calcined water-treatment plant sludges in mortar mixtures: A study on workability and strength

Mortar mixtures that consider alternative mineral admixtures are of constant research interest to reduce ordinary Portland cement (OPC) content thereby lowering final cost and carbon footprint. An additional concern is the proper management of industrial process residues that could be used in mortar mixes to avoid their disposal in landfills or water bodies. This work investigated the potential of using calcined water treatment plant sludge (CWTPS) and nitrophosphogypsum (NPG) - a byproduct of the fertilizer industry - as partial replacements of OPC in mortar mixtures. For this purpose, this research evaluates the crystallographic, chemical, and physical properties of NPG and CWTPS through X-ray diffraction (XRD), X-ray fluorescence (XRF), and Scanning Electron Microscope (SEM). XRF and XRD findings strongly suggests that CWTPS qualifies as supplementary cementitious materials, due to its high content of silicon and aluminum oxides in a non-crystalline state. On the other hand, NPG could be used as a mineral admixture. The design of mixtures was based on the workability of 85% flow. The evaluation of properties encompasses the measurement of density, compressive strength, durability (pH and sulfate environments), and water absorption. The results demonstrate that incorporating of NPG and CWTPS to mortar mixes, each at a 5% inclusion rate (with a total replacement of 10% of OPC), increase compressive strength by up to 6.65% at 90 days compared to the control group in mortar mixes. However, the inclusion of NPG and CWTPS significantly decreases the workability of mortar mixes by up to 51.49%. The utilization of NPG as a partial replacement for OPC increases the water-to-cement ratio proportionally compared to the control sample, which can be explained by the anhydrite content of this byproduct. For its part, replacing 10% of OPC with NPG and CWTPS results in a 1.99% decrease in resistance after 28 days in sulfated environments compared to specimens cured in lime water. This protection of NPG against sulfate attack on mortars is based on the fact that SO3 saturation hinders the phase change from AFt to AFm during curing, as demonstrated by the XRD results. Additionally, the inclusion of NPG in mortar mixes increases capillary water absorption by up to 19.8%, while CWTPS, due to its pozzolanic nature, reduces it by up to 5.75%. Finally, this study explores the potential combined use of NPG and CWTPS in mortar mixes as a partial replacement for cement, presenting a viable and sustainable alternative for these cementitious-based construction materials.

On the influence of iron and silicon content on the phase composition of the Al-Fe-Si system

Increasing interest in intermetallic phases of the Al-Fe-Si system is associated with their high specific strength, corrosion and wear resistance, as well as the low cost of their production. To exhibit the most successful combination of properties, it is necessary to impart a specific compact morphology to the precipitated intermetallic phases. It is important to create an alloy with a composition capable of accepting plastic deformation. The purpose of the work is to develop the composition of an Al-Fe-Si system alloy capable of withstanding plastic deformation and determining the corresponding deformation interval. Based on computer modeling, an alloy composition capable of accepting plastic deformation was developed and the corresponding deformation interval was determined. The simulation was carried out in the ThermoCalc software package, TCAL8 database. It has been revealed that alloys with a high content of both silicon and iron are not characterized by the formation of a single-phase region, however, with a certain combination of alloy components, it is possible to achieve a quasi-single-phase structure, when the content of one phase is observed to be more than 90%. The solidus temperatures for different alloy compositions and the boundary conditions for the existence of phases have been determined. The α phase is present in the system from a temperature of 770°C up to a temperature of 446°C. In composition, it is found in the range from 5 to 35% iron with an amount of silicon of 10% and from 0 to 15% silicon with an iron content of 30%. The maximum amount of α phase was obtained for the Al60-65 alloy; Fe30-32; and Si5-10%, deformation temperature range is 600-450°C. Deformation in this region will ensure processing in a quasi-single-phase region without melting.

Investigation of the influence of cobalt content and grain size of WC-Co cemented carbides on wear when shear cutting electric sheet metal

In the production of electrical machines, shear cutting of electrical steel laminations before further processing into rotors and stators represents an essential manufacturing process. Investigations have shown that using abrasively worn active elements while shear cutting increases the hysteresis losses in the electrical steel sheet due to introduced deformations and resulting residual stresses. Therefore, knowledge of suitable tool materials is of great importance for producing high-quality electric motors. Due to its high silicon content, electrical steel has a strong abrasive effect on the tools, which is why Tungsten carbide cobalt (WC-Co) cemented carbides are commonly used. In this work, continuous stroke tests are carried out on an electric sheet with punches made of different WC-Co cemented carbides, differing in cobalt content and grain size. The punches are examined with increasing wear regarding cutting-edge geometry, surface condition and microstructure. The resulting cutting parts are inspected for cutting surface characteristics. In addition, the influence of geometry and tribology of the punches regarding residual stresses in the material is investigated by FEM-Simulation. The investigations will provide information on the wear development and causes when shear cutting electrical sheets and the effects on electric losses.