Search

Geopolymers represent a distinct class of materials characterised by their X-ray amorphous nature and nanoporous, nanoparticulate structure. Geopolymers can be conveniently mixed, poured, and cured under ambient conditions. This makes this class of materials an interesting alternative to ordinary Portland cement for structural processes. Additionally, the addition of alumina can improve mechanical properties, while the addition of glass can form an impermeable glaze which could be useful for molten salt containment. Therefore, in this investigation, potassium metakaolin-based geopolymer composites with varying proportions of glass particles and alumina platelets were fabricated, cured, heat-treated, and analyzed to study the effects of composition on material properties. Various attributes including rheological properties, densities, mass loss, shrinkage, and porosities were compared. It was observed that certain compositions exhibited high viscosities, making high shear mixing challenging, while also displaying significant permeability that would hinder their ability to contain liquids without leakage. Additionally, certain samples showed reduced densities, suggesting potentially weaker mechanical properties; however, the investigation did not include a direct assessment of mechanical properties. The most promising candidates for containing liquids at high temperature contained 50 wt% KGP, 25 or 35 wt% glass powder, and 25 or 15 wt% alumina platelets, respectively. ASH-G slurries required a minimum of 65 vol% KGP to produce a homogenous material compatible with additive manufacturing. The minimum amount of glass phase to form surface glazes was 16 vol%. Only samples containing more glass phase than alumina phase produced glazed composites. [ABSTRACT FROM AUTHOR]

Grouting Fire Prevention technology is the most commonly used technology in coal mines. In order to improve the water holding capacity of the slurry and prevent the cracking and re-leakage of air caused by the loss of water, this paper used sodium alginate, sodium polyacrylate and gasification slag to prepare thick paste mixture, and then used calcium chloride to induce the gelation of the mixed paste surface to form an elastic solid film. A kind of environmental protection slurry of coated gasification slag (hereinafter referred to as coated slurry) with good environmental protection, high strength and elastic solid film with flame retardant and water retention on the outer surface was developed. In the 30°C-300°C range, when the coated slurry was heated, it would have a significant heat absorption and cooling effect. The results show that the hydrophilic -COO-, -OH in sodium alginate forms a synergistic effect with -COO-, -COOH in sodium polyacrylate, and enhances the water absorption of sodium polyacrylate; The interaction of calcium ions with sodium alginate on the surface of the mixed slurry causes gelation and forms a calcium alginate film on the surface of the coated slurry, which prevents water evaporation. [ABSTRACT FROM AUTHOR]

In this work, magnesia‐alumina spinel foam ceramics were prepared by foaming‐sol method using magnesia alumina spinel as raw material, anionic surfactant potassium oleate (PO) as foaming agent, and alumina sol as curing agent. The curing mechanism and the effect of alumina sol content on the stability of foam slurry and the properties of foam ceramics were investigated. In the foam slurry, the alumina sol can react with PO, so magnesia‐alumina spinel can be fixed in the foam structure through the gel network to improve the stability of the foam slurry. The gelation process reduces the viscosity of the foam slurry. The pores of magnesia‐alumina spinel foam ceramics sintered at 1500°C are mostly closed pores and the average pore was 29.7–42.1 µm. With the increase of alumina sol content, the bulk density of magnesia‐alumina spinel foam ceramics increased from 1.3 to 1.9 g/cm3, the cold compressive strength from 8.8 to 22.7 MPa, and the thermal conductivity from.417 to.806 W·m−1·K−1(350°C). [ABSTRACT FROM AUTHOR]

Porous vitrified bond diamond grinding wheels are commonly used for grinding hard and brittle materials. However, uneven pore distribution and low porosity affect the grinding performance of the wheel significantly. In this study, three types of triply periodic minimal surface porous vitrified bond diamond grinding wheels—Gyroid, Diamond, and Lidinoid–were prepared through parametric designing and digital light processing 3D printing. The grinding wheel achieved a uniform distribution and an interconnected pore structure. The key to high-performance grinding wheel via stereolithography 3D printing lies in the preparation of the slurry with high solid loading, low viscosity and uniform stability. Hence, the effect of surface modifiers on the slurry, along with the effect of sintering temperature and the microscopic and mechanical properties, was investigated. By grinding the SiC ceramics, the material removal rate, grinding temperature, and surface roughness were compared to those achieved using a conventional solid-structure grinding wheel. The results show that the slurry with the highest solid content of 80 wt% (58 vol%) and viscosity of 4.21 Pa s (30 s−1) can be prepared using surface-modified particles. The diamond grinding wheel sintered at 680 °C exhibits the best comprehensive performance. A grinding wheel prepared using stereolithography 3D printing can achieve better surface roughness and lower the grinding temperature. [ABSTRACT FROM AUTHOR]

Porous β-Si 3 N 4 /Si 5 AlON 7 composite ceramics are anticipated to serve as high-temperature wave-transparent materials, yet the fabrication of high-performance porous β-Si 3 N 4 /Si 5 AlON 7 composite ceramics remains a significant challenge. Addressing this issue, this study introduces a technique for crafting high-performance porous β-Si 3 N 4 /Si 5 AlON 7 composite ceramics. This method involves the homogeneous blending of SiO 2 and Si 3 N 4 powders, followed by digital light processing and high-temperature liquid-phase sintering at 2000 °C. The impact of SiO 2 content on various properties of the ceramic slurry and the resultant ceramics was thoroughly examined, including rheology, curing depth, microstructural morphology, phase composition, flexural strength, hardness, dielectric constant, and dielectric loss. It was observed that a SiO 2 content of 30 % enables the slurry to fulfill the criteria for digital light processing, leading to the production of porous β-Si 3 N 4 /Si 5 AlON 7 composite ceramics that exhibit outstanding mechanical and dielectric properties. Specifically, these ceramics demonstrated a flexural strength of 149.2 ± 7.2 MPa and a hardness of 11.8 ± 1.1 GPa. Moreover, at a frequency of 10 GHz, the ceramics exhibited a dielectric constant of 4.02 and a dielectric loss of 0.11, highlighting their potential as high-temperature wave-transparent materials. [ABSTRACT FROM AUTHOR]

To solve the problem of the proportional design of cement concrete prepared by using manufactured sand instead of river sand, a new method of manufactured sand concrete mix design was proposed with the dense packing of coarse and fine aggregate. Compared with the original sieving method, the stone powder in the manufactured sand can be regarded as cementitious materials for slurry. With the proposed mix design method, there is no need to separate from the manufactured sand. This dense packing method considers the actual situation that both the manufactured sand and coarse aggregate are mechanically prepared, and all the aggregates can be unified in proportion. The composition ratio of aggregate with particle size greater than 0.075 mm is designed by the maximum density theory, and the rest of the part (below 0.075 mm) is treated as a cementitious material. As a parameter of the maximum density theory, the Fuller index of 0.45 was verified when the calculation values agreed well with the test results. With the proposed mix ratio design method, the different grades C30, C40, and C50 of manufactured sand concrete were designed. Furthermore, the properties such as workability and mechanical properties for the designed manufactured sand concrete were investigated to determine the applicability of the proposed mix design method. The test results show that the workability, uniformity, and strength of the manufactured sand concrete were better than the original mix ratio design method, which verifies the operability and reasonableness of the proposed mix ratio design method. [ABSTRACT FROM AUTHOR]

To address the engineering problem of wall collapse and destabilization during the construction of the slurry trench wall, the stability of the slurry trench wall under the condition of three-dimensional (3D) unsaturated stable seepage is studied using the upper limit analysis method and in combination with the three-dimensional rotating failure mechanism. The expression of the factor of safety (FS) for the unsaturated soil slurry trench was deduced by the gravity increase method. Additionally, a genetic algorithm was used to search for the minimum FS and the critical slip surface, and the obtained results were compared and validated with existing literature results. The effects of relevant parameters on the stability of the slurry trench under the condition of unsaturated seepage were analyzed in detail. The results of this paper indicated that ignoring the 3D effect of the slurry trench will underestimate the stability of the slurry trench. The presence of suction in unsaturated soil is beneficial to the stability of the slurry trench, and the impact of suction is closely associated with seepage conditions and the characteristics of the soil. The increase in surcharge load can lead to a decrease in the FS, and its effect on slurry trench stability increases with the enhancement of the three-dimensional effect. The impact of different seepage conditions on the sliding surface of the channel wall of clay strata is more significant, while the effect on the trench wall of sand strata is negligible. [ABSTRACT FROM AUTHOR]

The use of prefabricated horizontal drains (PHDs) combined with vacuum preloading (VP) has emerged as a popular dredged slurry treatment strategy. However, few theoretical contributions are available to assess its consolidation characteristics in practical engineering design and applications. In this context, an analytical model is proposed to predict the consolidation behavior of the dredged slurry with assistance of PHDs subjected to VP. Initially, an equivalent cylindrical unit cell is established in accordance with the area equivalence principle. Then the governing equation and analytical solution are derived by converting the external loading into the lateral loading acting on the typical unit cell. In the current model, the layered filling process of dredged slurry and the corresponding layered layout patterns of PHDs are comprehensively incorporated. Furthermore, an in-depth assessment is conducted to explore the impacts of several crucial parameters on the consolidation performance. Additionally, a laboratory model experiment is carried out to treat the dredged slurry by a double-layer crosswise layout of PHDs in combination of VP. Thereafter, the accuracy and reasonability of the obtained solution are validated through degradation analysis and experimental data. Based on the parametric analysis and experimental outcomes, compared with prefabricated vertical drains (PVDs), the use of PHDs is observed to facilitate the transmission of vacuum pressure and ensure a more uniform settlement of dredged slurry, thereby ultimately improving dewatering efficiency. [ABSTRACT FROM AUTHOR]

The combined effects of particle concentration (0–20 vol%) and particle size on the hydrodynamics of a slurry bubble column were studied by computational fluid dynamics coupled with population balance model (CFD‐PBM) in a wide range of superficial gas velocity (0.02–0.20 m/s). This CFD‐PBM coupled model included multiple effects of particles, namely increased slurry viscosity, reduced drag force, promoted bubble coalescence, and attenuated liquid turbulence, among which turbulence attenuation was crucial. To quantify liquid turbulence attenuation, a mechanistic model was established by equating the energy dissipated by particle motion to the attenuated liquid turbulence energy calculated from turbulent energy spectrum. The turbulent energy dissipation rate was reduced by over 60% at a solid concentration of 20%. Using this model, the effects of particle concentration and particle size on overall gas holdup were well predicted. This model advanced our understanding of how particles affect the gas holdup in a slurry bubble column. [ABSTRACT FROM AUTHOR]

In underground mine environments, factors such as low light intensity, diffusion of dust particles, and coal slurry coverage interfere with coal gangue identification. To further realize coal-gangue sorting underground, we analyzed the coal-gangue visual characteristics coupled with the above factors. The analysis reveals that both smoke environments and coal slurry coverage tend to make the coal-gangue visual features more consistent. There are still differences in coal-gangue visual features under smoke environments, while coal slurry coverage leads to gangue exhibiting coal-related feature information. To improve the detection capability of coal gangue in underground environments, this study adopts a coal gangue recognition method based on the DG module and YOLOX-PSB network: Utilize the DG module to achieve dehazing and then use the YOLOX-PSB model for object detection. The proposed method was validated through ablation experiments, and the results showed that the detection accuracy reached 99.6%, with an FPS of 98. The proposed method enables real-time detection and exhibits the best robustness in complex environments, realizing reliable and efficient performance. [ABSTRACT FROM AUTHOR]

Pig slurry can be used as an alternative source for nutrients, particularly nitrogen (N), for plants. However, after applying the pig slurry to the soil, gaseous loss of N this nutrient may occur, mainly in the form of ammonia. Hence this study aimed to evaluate the loss of N by volatilization after the application of pig slurry with an acidified pH. Ammonia volatilization was evaluated using pig slurry, with its pH modified to 5.0 using four acids (sulfuric acid, citric acid, ascorbic acid, and acetic acid). Additionally, pig slurry with natural pH and a control were also used. The work was conducted in a greenhouse, and collectors were used to capture the volatilized ammonia in a static free semi-open chamber. The application of pig slurry with natural pH (7.19) resulted in 61% loss of ammonia, whereas acidification with ascorbic acid (pH 5.0) caused a loss of only 26%. The application of pig slurry with pH above 7.0 caused N loss, indicating that using acids to maintain a pH of 5.0–6.0 could be an alternative to reduce N loss by ammonia volatilization. [ABSTRACT FROM AUTHOR]

Alumina toughened zirconia (ATZ) ceramics combine high biocompatibility with remarkable mechanical properties, making them suitable for dental and orthopedic implant applications. Producing these ATZ ceramics using slurry-based additive manufacturing necessitates homogeneous, stable suspensions with controlled particle sizes. Stabilizing such systems with the appropriate type and amount of dispersant is challenging, particularly since multi-component systems are prone to hetero-coagulation. In this study, ATZ powders with different surface areas were investigated to determine the optimum concentration of three commercially available dispersants: Darvan CN, Darvan 821 A, and Dolapix CE64, which have been successfully used to stabilize Al 2 O 3 and 3Y-TZP suspensions. Based on zeta potential (0.01 vol% suspensions), agglomerate size (0.01 vol% suspensions), sedimentation (10 vol% slurries), and rheological (40 vol% slurries) characterization, the optimum dispersant concentrations were found to be 0.50 mg/m2 for Dolapix CE64, 0.75 mg/m2 for Darvan 821 A, and 1.50 mg/m2 for Darvan CN. Among the studied dispersants, Dolapix CE64 was the most effective in terms of reduced sedimentation, smaller agglomerate size (0.70 μm), flow behavior, and low resistance to structure breakdown. The rheological assessment showed that slurries prepared with ATZ powder featuring a smaller specific surface area (7.3 m2/g) resulted in lower viscosity, critical stress, and equilibrium storage and loss moduli compared to those prepared with higher specific surface area (13.3 m2/g) starting powder. The sedimentation analysis however revealed that the larger specific surface area ATZ powder exhibited higher slurry stability. While 38 vol% ATZ pastes without dispersant showed inhomogeneous extrusion and the presence of aggregates, the filaments extruded from 45 vol% paste with 0.50 mg/m2 Dolapix CE64 had a homogeneous and smooth structure and were free of aggregates, highlighting the importance of the dispersant addition for DIW. [ABSTRACT FROM AUTHOR]

Grouting is a widely used geotechnical procedure known for its strong empirical properties. It has been extensively utilized for sealing subterranean water and strengthening soil and rock masses in their original locations in underground mining and underground space development. The diffusion mechanism of grouting in fractured rock is affected by the geological environment and slurry performance, which should be better revealed and characterized. In this paper, we take the surrounding rock of the roadway as the research object, consider the stress condition of the injected rock and time-dependent viscosity of the slurry, and establish fracture grouting diffusion model based on the rock composite fracture criterion. The grout strengthening mechanism is discussed based on a transparent fracture replica grouting test. According to the different transport characteristics of the slurry interacting with flowing water, it is divided into the following four areas grout-water balance area, grout loss area, stagnation area and water passage. The grout plugging mode is divided into two categories according to its final diffusion pattern: cross-section type water plugging mode and water-drop plugging mode. The pressure monitoring data of the test verified the two grout plugging modes. The diffusion distance of cis-reverse water derived in this study was in good agreement with the experimental results in grouting early stage. The research results can provide a theoretical basis for grouting engineering design. • Fracture grouting diffusion model based on the rock composite fracture criterion. • The grout strengthening mechanism is discussed based on a transparent fracture replica grouting test. • Slurry travel is divided into the following four areas, grout-water balance area, grout loss area, stagnation area and water passage. • The grout plugging mode is divided into two categories according to its final diffusion pattern. [ABSTRACT FROM AUTHOR]

A 2.8 MM TPY heavy oil catalytic cracking unit in a refinery has been undergoing slurry recycling for about six months under low processing capacity. The recycling method involves injecting the recycled slurry into the mixed feedstock oil at the feedstock self-protection assembly and then into the feedstock oil nozzle. After calibration, the yield of coke increases from 7.86% to 8.41%, accounting for about 20% of the recycled slurry to produce coke. The diesel yield of the unit has increased, and about 50% of the recycled slurry has been converted or becomes high-value diesel products. The slurry recycling resulted in a decrease in the overall conversion rate of the unit, with a total reduction of 1.93 percentage points in the yields of dry gas, liquefied petroleum gas, and gasoline. During the recycling process of slurry, the unit monitors the feedstock oil and reaction system, and has not found any significant impact on coking in the reaction system, wear of the feedstock oil pipeline and nozzle, or other defects. Subsequent defect elimination inspections have also not found any abnormalities. Overall, the recycling of slurry increases the coke yield of the unit, ensures steam balance in the entire plant under low processing capacity, and effectively reduces the solid content of slurry, resulting in a decrease in the yield of slurry in the unit. [ABSTRACT FROM AUTHOR]

Generally, 100% vacuum residue is not processed in fixed-bed residue hydrogenation units, and the proportion of vacuum residue in feedstock is not higher than 65% . The A fixed bed residue hydrogenation unit has six cycles, and the operating results show that the higher the proportion of vacuum residue in feedstock, the shorter the operating cycle of the unit. The volume space velocity of the B fixed bed residue hydrogenation unit is 0.20 h-1. If the volume space velocity decreases to 0.15 h-1 and 0.10 h-1, the reactor pressure drop is expected to increase to 2.3 MPa and 3.4 MPa, respectively. The yield of hydrogenated heavy oil in the A fixed bed residue hydrogenation unit is as high as 93.25%, and the conversion rate of fractions above 520 °C is only 25.38%. Ebullated bed residue hydrocracking technology and slurry bed residue hydrocracking technology can process vacuum residue. The pressure drop in the reactors of the ebullated bed unit C and the slurry bed unit D is stable, with a pressure drop of only 0.42 MPa in reactor of unit D. The conversion rates of typical ebullated bed residue hydrocracking technology and slurry bed residue hydrocracking technology can reach 85.87% and 91.49%, respectively. [ABSTRACT FROM AUTHOR]

A digital process was developed to facilitate additive manufacturing for ceramic materials using digital light processing (DLP). A numerical model that predicts DLP sample properties can be generated from manufacturing inputs to forecast the effect of resin age on mechanical strength of the printed part based on data collected from experiments. Key parameters for printing the green bodies included determining the depth of cure, layer thickness, material composition, and solids loading. Thermogravimetric analyses were used to develop debinding and sintering curves. Debinding is used to remove the volatile organics comprising the photopolymer resin. Sintering is performed after debinding to increase density and mechanical strength of the printed parts. The sintered parts were then subjected to characterization and mechanical testing. The ensemble of data for various DLP-printed ceramic materials were added to a database. A design of experiments can be generated from the manufacturing process defined in the database with selected changeable parameters randomized over a range. Because the database is defined with an architecture to capture manufacturing processes, it can persist as a more generic platform for manufacturing digital twins. This can ease the development of future digital twins and can grow as a common repository for the insights gained from manufacturing research. Creating a digital twin of a DLP system for 3D printing parts enables manufacturers to simulate and assess the impact of resin age on printing parameters and part quality, facilitating optimization, predictive maintenance, and cost reduction. [ABSTRACT FROM AUTHOR]

When wet soil becomes fully saturated by intense rainfall, or is shaken by an earthquake, it may fluidize catastrophically. Sand-rich slurries are treated as granular suspensions, where the failure is related to an unjamming transition, and friction is controlled by particle concentration and pore pressure. Mud flows are modeled as gels, where yielding and shear-thinning behaviors arise from inter-particle attraction and clustering. Here we show that the full range of complex flow behaviors previously reported for natural debris flows can be reproduced with three ingredients: water, silica sand, and kaolin clay. Going from sand-rich to clay-rich suspensions, we observe continuous transition from brittle (Coulomb-like) to ductile (plastic) yielding. We propose a general constitutive relation for soil suspensions, with a particle rearrangement time that is controlled by yield stress and jamming distance. Our experimental results are supported by models for amorphous solids, suggesting that the paradigm of non-equilibrium phase transitions can help us understand and predict the complex behaviors of Soft Earth suspensions. Regarding the failure and flow of wet soil, a question that remains is how soil material composition influences rheology. Based on Soft Earth suspension flow experiments, the authors discover a continuous transition from frictional-to-cohesive rheology recreating all complex behaviors reported for natural soil slurries. [ABSTRACT FROM AUTHOR]

To determine the stability and hardening strength characteristics of waste rock-ungraded tailings slurry in a gold mine, tests were conducted on the slurry-s bleeding rate, stratification degree, and hardening strength. The stability of the filling slurry was evaluated using the bleeding rate and stratification degree as indicators. An in-depth analysis was performed on the uniaxial stress-strain curve, failure behavior, factors influencing the strength, and the evolution of the filling bodys strength. Based on the test data, a regression model for the strength of the filling body was established and verified through supplementary tests. The test results showed that when the concentration is below 68 %, the proportion of waste rock has a dominant effect on the stratification degree. When the concentration exceeds 68 %, the influence of waste rock addition on slurry segregation decreases, while changes in the cement-sand ratio lead to reduced anti-segregation performance. Under conditions of a high cement-sand ratio, increasing the proportion of waste rock reduces the elastic strain value, whereas the plasticity of the filling body decreases as the waste rock proportion increases. The main strength increase of the filling body occurs within the first 0-7 d of curing, after which the rate of strength growth gradually slows. Factors influencing the rate of strength growth are cement-sand ratio>slurry concentration. The established regression model for predicting the filling slurry mix parameters shows an error margin within ±15 %, making the model reliable for providing a reference for future mix optimization. [ABSTRACT FROM AUTHOR]

The coupling effect between the spatial variability of slurry diffusion and the time-varying viscosity of quick-setting slurry is the time–space characteristics of slurry viscosity (TSCSV). The TSCSV is the governing factor for the complex and uncontrollable flow of slurry in fractures. In this regard, the flow pattern of quick-setting slurry is considered as a Bingham fluid with viscosity spatiotemporal characteristics. Using the fractal function with random parameters (W-M function), a single fracture with random fracture opening (RFO) is drawn, and a theoretical model on grouting diffusion in fractures is established considering the TSCSV. The RFO is corrected for head loss, and the spatiotemporal distribution equation of the RFO grouting pressure is derived. The relationship between grouting pressure, grouting time, and slurry diffusion distance is obtained. Additionally, the effects of the RFO, the fractal dimension of the fracture curve, the horizontal movement distance of the lower end face of the fracture, and the effects of viscosity and grouting rate on the viscosity and grouting pressure in the slurry diffusion space are discussed. Finally, by predefining the spatial distribution function of slurry viscosity for a single fracture in the numerical calculation model, a numerical simulation of random fracture distribution grouting considering viscosity spatiotemporal characteristics is achieved. The rationality of the model is validated through a comparison of theoretical analysis and numerical simulation, providing reference for the determination of grouting parameters in practical grouting projects. [ABSTRACT FROM AUTHOR]

Quality control in a production plant shows its maximum potential in the form of inline measurements. Defects and imperfections can be detected early and directly, and waste and costs can be reduced. Nuclear Magnetic Resonance offers a wide range of applications but requires dedicated adaptation to the respective process and material conditions. A V-shaped low-field NMR sensor was developed for non-invasive inline measurements on anode slurries in a battery production plant. In battery production, inline monitoring of the quality of anode slurries is demanded, offering the possibility of predictive control of the following process steps. Methods of low-field NMR to determine flow properties were adapted to the desired application. Further, magnetic resonance imaging measurements were made to determine the flow properties of model substances and anode slurries, thus providing verification. The sensor measurements show the ability to measure the flow behavior of, amongst other fluids, anode slurries in a form suitable for inline quality control in a battery production plant. [ABSTRACT FROM AUTHOR]

A lanthanum–cerium-based abrasive composed of CeO2, LaOF, and LaF3 was commercially obtained. The effect of sodium hexametaphosphate (SHMP) on powder dispersion behavior was systematically investigated using the combined techniques of liquid contact angle, turbidity, zeta potential (ZP), scanning electron microscopy (SEM), powder X-ray diffraction (XRD) combined with Rietveld refinements, X-ray photoelectron spectroscopy (XPS), and polishing tests. The results indicated that the addition of 0.5 wt.% SHMP dispersant to the 5 wt.% lanthanum–cerium-based slurry produced the most stable suspension with a high turbidity of 2715 NTU and a low wetting angle of 45°. The as-obtained slurry displayed good surface polishing quality for K9 glass, with low surface roughness (Ra) of 0.642 and 0.515 nm (in the range of 979 × 979 μm2) at pH = 6 and 11, respectively, which corresponds to the fact that it has local maximum absolute values of ZP at these two pH values. SEM images demonstrated that after appropriate grafting of SHMP, the particle aggregation was reduced and the slurry's dispersion stability was improved. In addition, the dispersion mechanism was explained based on the principle of complexation reaction, which reveals that the dispersant SHMP can increase the interparticle steric hindrance and electrostatic repulsions. In an acidic environment, steric hindrance dominates, while electrostatic repulsion prevails under alkaline conditions. As expected, this polishing slurry may find potential applications in manufacturing optical devices and integrated circuits. [ABSTRACT FROM AUTHOR]

Synchronous grouting technology is a crucial aspect of shield tunnel construction. However, understanding the mechanism of slurry diffusion during this process is challenging due to its complexity and invisibility. Existing theoretical models often oversimplify the grouting process and do not account for multi‐stage diffusion mechanisms. By considering the radial penetration of slurry and viewing the diffusion process as the formation of annular pancakes through circumferential filling, a 3D diffusion numerical model is established using the volume of fluid (VOF)‐multiphase flow model in Fluent software. The model's validity is confirmed through calculations based on theoretical formulas and monitoring data from engineering examples. This study uncovers the patterns of slurry diffusion and examines how factors like porosity, grouting pressure, and slurry density impact diffusion radius and segment stress. The findings of this research provide a crucial theoretical foundation for shield synchronous grouting construction. [ABSTRACT FROM AUTHOR]

Porous Si3N4 ceramics were prepared using the low‐toxicity monomer HEMA (2‐hydroxyethyl methacrylate) via a modified gel casting method. The rheological properties of Si3N4 slurries were investigated. Triethanolamine with high activity was used as a catalyst and modifier for gelation reactions, effectively improving the curing rate and suppressing the inherent surface oxygen inhibition in such process systems. With an increase in solid loading of the slurry, the drying shrinkage (12.3% to 5.4%) significantly decreased, while the green body density (44.0%–49.0%) and flexural strength (9.65–16.46 MPa) increased, demonstrating an excellent mechanical strength. After sintering at 1700°C, the porous Si3N4 ceramics prepared with 24–36 vol% solid loading slurry exhibited a flexural strength of 144.39–193.66 MPa and a porosity of 55.8% to 49.0%. The dielectric constant and loss tangent at 30 GHz ranged from 2.88 to 3.38 and 1.17–1.56 × 10−3, respectively. These ceramics show promising potential applications in high‐performance structural ceramics and high‐temperature wave‐transparent materials. [ABSTRACT FROM AUTHOR]

During the underground excavation, various flaws are frequently observed, which significantly decrease the mechanical properties of surrounding rock, as has been proven. As known, grouting technology is a means of reinforcement that efficiently enhances the stability of underground engineering. However, existing studies have mainly focused on increasing the strength of the slurry stone, and relatively less attention has been paid to the poor bonding effect at the interface between the slurry and the rock mass. In this work, we proposed to adopt slurry containing nano-silica sol to reinforce the fractured rock mass. Based on the mechanical model of micro–nano-siliceous slurry reinforcement for single fractured rock masses established in this paper, the effect and the mechanism of micro–nano-siliceous slurry reinforcement for fractured rock were explored through theoretical analysis, laboratory tests, and numerical simulations. Results showed that the application of micro–nano-siliceous slurry increased the friction and the bonding force at the slurry–rock interface, which led to a (σn·Δμ + Δc) reduction of the effective stress. The optimum incorporation rate of the nano-silica sol was determined to be 3% based on these indicators including slurry fluidity, slurry stone rate, and strength and deformation parameters of slurry stone. The peak strength of the sandstone specimens reinforced by the micro–nano-siliceous slurry increased by 16.49% those of the sandstones reinforced by the ordinary slurry, and the elastic energy accumulated by the former was higher. Scanning electron microscope images revealed that the incorporation of nano-silica sol distinctly improved the pore characteristics of the slurry-rock interface. Finally, on the basis of 1790 ventilation roadway of Shiyakou coal mine, the effectiveness and the feasibility of micro–nano-siliceous slurry for reinforcing underground engineering surrounding rocks were verified using numerical simulation. Highlights: This paper developed a new micro–nano-siliceous grouting material. A mechanical model for fractured rock mass reinforced by new slurry was proposed. The optimal incorporation rate of nano-silica sol was determined by various means. This study demonstrated the effectiveness of the new grouting material in reinforcing fractured rock mass by control lab experiments and numerical simulation. The mechanisms of micro–nano-siliceous slurry to improve slurry–rock interface were revealed. [ABSTRACT FROM AUTHOR]

• S-NZVI/rGO@GG slurry showed excellent stability and mobility performance. • Higher GG concentration, pH, and low ionic strength are beneficial to improve the transportability of S-NZVI/rGO@GG slurry. • Brownian action dominates S-NZVI/rGO@GG slurry deposition in saturated porous media. • CFT, XDLVO, and kinetic fitting were combined to explain attenuated Brownian motion and GG spatial repulsion play a key role in migration. Nanoscale zero-valent iron (NZVI), which has the advantages of small particle size, large specific surface area, and high reactivity, is often injected into contaminated aquifers in the form of slurry. However, the prone to passivation and agglomeration as well as poor stability and mobility of NZVI limit the further application of this technology in fields. Therefore, sulfided NZVI loaded on reduced graphene oxide (S-NZVI/rGO) and guar gum (GG) with shear-thinning properties as stabilizers were used to synthesize S-NZVI/rGO@GG slurries. SEM, TEM, and FT-IR confirmed that the dispersion and anti-passivation of NZVI were optimized in the coupled system. The stability and mobility of the slurry were improved by increasing the GG concentration, enhancing the pH, and decreasing the ionic strength and the presence of Ca2+ ions, respectively. A modified advection-dispersion equation (ADE) was used to simulate the transport experiments considering the strain and physicochemical deposition/release. Meanwhile, colloidal filtration theory (CFT) demonstrated that Brownian motion plays a dominant role in the migration of S-NZVI/rGO@GG slurry, and the maximum migration distance can be increased by appropriately increasing the injection rate. Extended-Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory showed that the excellent stability and migration of S-NZVI/rGO@GG slurry mainly came from the GG spatial forces. This study has important implications for the field injection of S-NZVI/rGO@GG slurry. According to the injection parameters, the injection range of S-NZVI/rGO@GG slurry is effectively controlled, which lays the foundation for the promotion of application in actual fields. [Display omitted] [ABSTRACT FROM AUTHOR]

Utilizing recycled concrete aggregate (RCA) is a countermeasure to address the scarcity of landfills and the depletion of natural aggregates. Surface modification techniques have been proposed and implemented to improve the properties of RCA; however, to our best knowledge, few investigations on improving RCA under various pozzolanic slurry concentrations and extended soaking durations have been done. This study comprehensively assessed the properties and microstructure of low-strength RCA treated with cement–fly ash slurry with different concentrations and soaking durations. The purposes of this study were not only to provide the optimal slurry concentration and treatment duration but also to explore the enhancement mechanism of RCA under various treatment conditions. The RCA from concrete with a low-strength grade of 20 MPa was soaked in cement–fly ash slurry at low and high concentrations (i.e., 30% and 70% by mass of RCA, respectively) for 24 and 72 h. The physical and mechanical properties of RCA before and after treatment were evaluated through water absorption and crushing value measurements, respectively. Additionally, the pore structure, Ca(OH)2 contents, surface morphology, and phase compositions of RCAs were evaluated through a mercury intrusion porosimetry test, thermal gravimetric differential thermal analysis (TG-DTA), scanning electron microscopy, and X-ray diffraction (XRD) analyses, respectively. The water absorption of treated RCA reduced by 9.2%–37.9%, whereas the crushing value decreased by 8.6%–26.9% compared with the untreated RCA. The TG-DTA results indicated a 22.3%–43.8% increase in the Ca(OH)2 content of treated RCA. The XRD analysis depicted a higher ettringite (AFt) peak in all treated RCA samples compared with the untreated sample. For both concentrations, with a 24 h treatment, the slurry infiltration effect was clearly observable, whereas the 72 h treatment resulted in the formation of a pozzolanic coating layer on the RCA surface. In conclusion, the optimal slurry concentration and soaking duration were 70% and 72 h, respectively. [ABSTRACT FROM AUTHOR]

This study aims to clarify the mechanism of slurry support and its effect at different stages of slurry infiltration in shield construction. The analysis of various expressions of slurry support throughout the entire excavation cycle is based on the theories of slurry infiltration effects and the cutting action of the cutters. Furthermore, the limit support pressure calculation method at the tunnel face is modified considering the slurry support mechanism observed during different slurry infiltration stages. Some of the main conclusions drawn are as follows. (1) When slurry deep infiltration occurs, the main form of slurry support is the seepage force acting on the soil skeleton. At this stage, the limit support pressure from the filter cake model will not be sufficient to meet the tunnel face stability requirements. (2) The effectiveness of slurry support is influenced by both the slurry infiltration state and the cutting action of the cutterhead. Slurry infiltration and shield tunneling together create a quasi-static equilibrium state, in which slurry support is effective only when the infiltration velocity corresponding to this state is greater than the critical velocity. (3) And the influence of shield tunneling parameters on the slurry support mechanism is significant. Compared with the cutter's penetration degree, the cutter's rotational speed has a more pronounced effect on the conversion rate of slurry support pressure at the shield tunnel face. [ABSTRACT FROM AUTHOR]

When an earth pressure balance shield passes through soft-upper and hard-lower composite strata, it faces challenges such as cutterhead "mud cake" formation, inefficient muck removal, and tool wear. To address these issues, this study focused on silty clay-completely weathered granite composite strata and conducted laboratory tests on ground conditioning in different strata based on the adaptability and performance of soil conditioners. The study explored the effects of soil conditioners, such as foam agent and bentonite slurry, as well as their improvement methods on soft-upper and hard-lower strata, to determine an optimal ground conditioning scheme and the appropriate addition ratios for shield tunneling in composite strata. The results showed that: (1)Combining a 3% concentration foam agent solution with bentonite slurry at a 1 : 8 ratio yielded good results. (2)The silty clay strata were improved by foam agent. The slump of the muck increased with the foam addition ratio, while the shear strength, cohesion, internal friction angle, and permeability coefficient decreased. The optimal addition ratio of the soil conditioners was between 19. 7% and 22. 8%. ( 3) The completely weathered granite strata were improved using a combination of foam agent and bentonite slurry, which effectively enhanced the flow plasticity and impermeability of the muck. When using only foam, the optimal addition ratio was between 22. 2% and 28. 7%, while the combined foam and bentonite slurry method required a ratio of 24. 3% to 31. 5%. Field application and construction feedback showed that the above improvement scheme effectively enhanced the flow plasticity of the muck, and significantly improved the shield thrust, cutterhead torque and tool wear. [ABSTRACT FROM AUTHOR]

High-strength alumina (Al2O3 ) was utilized as a reinforcing phase to improve the strength of hydroxyapatite (HA), a bioactive material, but the HA-Al2O3 ceramics prepared by traditional hydrothermal method could not achieve the precise control of pore size and porosity, whereas the light curing additive manufacturing technology could achieve the high precision molding of HA-Al2O3 ceramics through the high-performance photocurable slurry. The state of HA-Al2O3 slurry is adjusted by the addition of dispersant, photoinitiator, and photoabsorbent to alleviate the severe scattering effect caused by the refractive index mismatch between HA powder, Al2O3 powder, and photosensitive resin. In this study, the effects of the type and content of photoinitiator and dispersant on the slurry were explored. The rheological and curing properties of the slurry are first improved and then weakened with the addition of both, and the optimal dosages of photoinitiator and dispersant are 0. 5% and 4% (mass fraction), respectively. The effects of two light absorbers, graphite and methyl yellow, on improving the printing accuracy were compared. Although graphite improves the printing accuracy and rheology of the slurry, it reduces the printing quality, so the dosage of 5.0 x 10-5 methyl yellow is determined, and finally HA-Al2O3 slurries suitable for high precision printing are obtained. [ABSTRACT FROM AUTHOR]

A new method is presented for the simultaneous determination of 13 multiclass pesticides along with glyphosate. The multiclass pesticides were extracted by creating a soil slurry with 2% ethanol in water (v/v), and then, applying direct-immersion solid-phase microextraction (DI-SPME) with a new type of semi-disposable SPME fiber configuration called LC-Tips. The fibers were then retroextracted to ethanol, and aqueous ammonia was added to the slurry to extract glyphosate. Derivatization of the glyphosate extract was accomplished with a mixture of trifluoroacetic anhydride and trifluoroethanol, after which the reaction mixture was dried and resuspended with the SPME ethanol extract. To this, a mixture of analyte protectants was added, and it was analyzed by GC-MS/MS in multiple-reaction-monitoring mode. All analytes showed a coefficient of determination greater than 0.95 in the 0.1–100 µg/kg calibrated range, and the limits of detection were between 0.1 and 1 µg/kg, except for glyphosate, which was 0.01 µg/kg. The method shows relatively high replicate relative standard deviation (as much as 37% for five extractions at 20 µg/kg), but the isotopically labeled internal standard was effective at mitigating this effect for some analytes. [ABSTRACT FROM AUTHOR]

Two-stage pressure leaching process is proposed to extract Ni from limonite-type and saprolite- type nickel laterite ore. The recommended conditions for the first stage high pressure acid leaching include acid ore ratio of 330 kg/t, temperature of 250 °C, slurry solid content of 30% and reaction time of one hour. The recommended conditions for the second stage pressure leaching include temperature of 230 °C, reaction time of one hour and slurry solid content of 35%. The nickel extraction rate of first stage high pressure acid leaching and second stage pressure leaching is 97.58% and 83.96% respectively, and the total nickel leaching rate is 93.81%, which greatly improves the utilization rate of nickel laterite ore resources. The Fe and Al concentration in solution can be reduced to below 1 g/L, which can reduce the amount of alkali used in subsequent neutralization processes. [ABSTRACT FROM AUTHOR]

One of the major environmental problems in hot and arid locations is the production of dust. This study presents green slurries based on nanoclay—and blast furnace slag for stabilizing desert sands. The slurries introduced contain bentonite and kaolinite mineral nanoclays, along with blast furnace slag powder. Unconfined compressive strength, moisture content, and wind tunnel tests were conducted to evaluate the performance of the compounds in stabilizing sand and increasing its water-holding capacity. The mass percentages of bentonite nanoclay and blast furnace slag in the stabilizer slurry were optimized at 1–3% and 1–5%, respectively. The optimized mass percentages of kaolinite nanoclay and blast furnace slag slurry were 1–1% and 3–1%. The study found that soil stabilized with slurries increased compressive strength by three times compared to unstabilized soil. Additionally, the addition of stabilizers improved soil moisture retention by 50%. Sand surfaces stabilized with nanoclays and slag demonstrated excellent resistance to wind erosion, even at wind speeds of up to 100 km/h. Furthermore, there was no wind erosion observed at 60 °C. The suggested slurry compounds have shown a strong ability to enhance the mechanical properties of soil, increase soil water retention, and reduce wind erosion of sandy soil. [ABSTRACT FROM AUTHOR]

The present study speaks of development of a two-dimensional phase field (PF) model to simulate the cooling slope rheoprocessing of the novel Al-15Mg2Si-4.5Si composite, in view of process optimization and investigation of physics of microstructure formation. In case of cooling slope rheoprocessing, the composite melt starts losing its superheat once it impinges over the slope and transforms into semi-solid slurry during its length of travel over the slope. After experiencing shear flow over the slope, the melt fills an isothermal slurry holding furnace where it undergoes coarsening for a certain length of time. The present PF model simulates how heterogeneous nucleation of solid grains is supposed to happen within the melt, during cooling slope processing, adopting a seed undercooling-based nucleation model. Moreover, the PF model implements a grain coarsening model to simulate the isothermal globularization process of the evolving solid grains of primary Mg2Si and primary Al phases. The interfacial free energy of Al–melt interface is taken from literature, whereas a molecular dynamics (MD) model is employed to estimate the interfacial energy value of the Mg2Si–melt interface. The cooling rate values employed in the present PF model for different melt pouring temperatures are determined experimentally from initial trial experiments, whereas the validation experiments are performed to collect the slurry samples from chosen locations of the melt flow front over the slope and from isothermally kept slurry holding furnace. Micrographs obtained from the above samples confirm the accuracy of the developed 2D PF model to capture microstructural morphology of the composite slurry. Moreover, the model predictions of quantitative parameters such as grain diameter, shape factor/sphericity, and solid fraction are found to be close to the experimental measurements. For example, a representative simulated value of grain size and sphericity of primary Mg2Si grains, after 8 minutes of slurry holding, are as follows: 24.01 and 0.834 μm, whereas the corresponding experimental values are 29.0 and 0.885 μm, respectively. [ABSTRACT FROM AUTHOR]

The rheological behavior and printing characteristics of the screen-printing slurry for Nd-Fe-B grain boundary diffusion are key factors that determine the quality of printing and magnetic performance. However, few studies have focused on the organic medium, a crucial material for slurry. In this paper, the rheology, thixotropy, and thermal decomposition behavior of the organic vehicle in Nd-Fe-B screen printing slurry were studied. The results show that the organic vehicle formed by terpineol and polyvinyl butyral (PVB) exhibits typical non-Newtonian fluid characteristics, with excellent rheology and thixotropy, ensuring that the slurry prepared from it has excellent static stability and printing consistency. Additionally, the carbon residue of the organic vehicle formed by terpineol and PVB is less than 0.1% at 900 °C, avoiding excessive carbon entering the magnet during the diffusion process. Moreover, studying the rheology and thixotropy of the organic vehicle through a rheometer can quickly screen the slurry system. This work provides valuable guidance for designing an organic vehicle for screen-printing slurry for Nd-Fe-B grain boundary diffusion in future research. [ABSTRACT FROM AUTHOR]

The inherent brittleness of ceramics poses significant challenges in the fabrication of hollow ceramic fibers, severely constraining their practical applications. In this study, a novel method for creating three-dimensional hollow fiber ceramic structures using UV-assisted single-channel direct ink writing was demonstrated. A concentric single-channel nozzle featuring shell/core structure was devised through the coaxial embedding method, and this specially designed nozzle was manufactured using digital light processing technology. During the UV-assisted direct ink writing process, the photosensitive ceramic slurry can be rapidly cured in place under the irradiation of UV light, ensuring high fidelity of the printed components. The hollow fiber structure produced in this study has a circular, pentagram, triangular and quadrilateral inner core, which can be adjusted according to the designed nozzle structure. This approach facilitates a straightforward and expedited creation of scaffolds featuring small-diameter hollow fiber structures, broadening the scope of potential applications for direct ink writing. [Display omitted] [ABSTRACT FROM AUTHOR]

Al 2 O 3 reticulated porous ceramics (ARPCs) are extensively employed in high-temperature catalytic support, molten metal filtration, and porous media combustion because of their high specific surface area and heat resistance. The high specific surface area is usually maintained by high apparent porosity, but unfortunately, the accompanying poor mechanical properties severely compromise the durability of ARPCs. To synergistically improve the mechanical properties and apparent porosity, a new strategy was proposed to prepare ARPCs with textured structures of in situ interlocking Al 2 O 3 platelet integration using vacuum impregnation Na 3 AlF 6 –SiC–Al 2 O 3 slurry technique. The obtained textural structure had a significant strengthening effect on ARPCs, attributed to the increased contact area among non-equiaxed grains, and the compact growth of Al 2 O 3 platelets with high aspect ratios provided the high apparent porosity and specific surface area of ARPCs, resulting in compressive strength as high as 3.93 MPa at an apparent porosity of 85.31 %, as well as the degradation of Congo red up to 75.35 % due to the Al 2 O 3 platelets facilitating the loading of TiO 2. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) is a multifunctional material with a myriad of potential applications, from high-power electronics to friction applications to power generation. Grafting preceramic polymers (PCPs) from SiC nanoparticles would create a platform for forming SiC via a polymer derived route that would have advantages over simple particle-PCP slurries and may enable new additive manufacturing inks or spreadable coatings with controlled rheology. Grafting PCPs directly on SiC powders would greatly improve dispersion of these particles and yield a single component system. Moreover, PCP-grafted-SiC would be a new addition to the burgeoning field of polymer grafted nanoparticles (PGNPs). Herein, SiC nanoparticles were surface-modified in a grafting-from polymerization reaction to create polycarbosilane (PCS) grafted SiC. Surface grafting was verified through a number of analytical techniques and the synthesized materials were pyrolyzed at 1600 °C. The PCS-grafted SiC retained 66 % of its pre-pyrolysis mass, representing a significant improvement over PCS-grafted silica nanoparticles from our previous work (20 wt% yield). In addition to an increased ceramic yield, the grafting of PCS to SiC also resulted in the formation of a SiC phase not present in the simple physical mixture of SiC nanopowder in PCS. This study demonstrated that PCP-grafted nanoparticles (GNPs) can be synthesized utilizing non-oxide nanoparticle cores with desirable rheology, opening possibilities for future ceramic inks and coatings. [ABSTRACT FROM AUTHOR]

We report the first work on the development of biodegradable acoustic foams from self‐grown bacterial cellulose (BC) from kombucha solution and green processing techniques. Kombucha BC‐agar and kombucha BC‐polyvinyl alcohol foams were fabricated by using slurries of BC pellicles mixed with the additives, froze for 24 h, and recast into foams using the freeze‐drying method. The foams were aerogel‐like with a density 20 kg/m3, thermally stable upto 220 °C, and crystallinity ~74%. Morphological analysis revealed macropores with coarse walls in agar‐based foams, whereas the PVA‐based foams comprised a polydisperse pore network with coarse walls. A broadband absorption was observed with a maximum of 0.4 for the 2.5‐mm‐thick single‐layer foams and 0.9 for the 12‐mm‐thick multilayer foams. The sound absorption was found to be on par with the biodegradable foams of agar and other cellulose‐rich materials such as agricultural residue, yet with a lightweight. Being largely porous, the foams had little transmission loss. As the densities and the crystallinities of these foams are tunable by the addition of other polymers, the results from this study provide scope to explore BC‐based lightweight materials for large‐scale fabrication suitable for sound absorption over specific regimes. [ABSTRACT FROM AUTHOR]

The solid electrolyte (SE) membrane plays a crucial role in sulfide‐based all‐solid‐state batteries (ASSBs). However, the challenge of finding appropriate polymer binders with excellent (electro‐)chemical compatibility and adhesive properties, remains a significant obstacle for wet slurry processing of sulfide SE membranes. Herein, a novel “polar‐nonpolar synergistic” finely‐tuned strategy is employed to design an ethylene‐methyl acrylate (EMA) copolymer binder to facilitate wet‐slurry‐based fabrication of sulfide SE membranes. Significantly, by adjusting the ratio of polar and nonpolar groups, this methodology enables the binder to dissolve effectively in a toluene‐based slurry and also ensures good adhesion between the EMA binder and SE particles. The SE membrane prepared with EMA binder exhibits an ultra‐thin thickness (36 µm), flexibility, and excellent ionic conductivity (1.43 mS cm−1). The ASSB assembled with the SE membrane shows an excellent capacity retention rate of 92.9% after 120 cycles at 0.5 C. This work on the “polar‐nonpolar synergistic” finely‐tuned effect of binder provides insight for manufacturing high‐quality sulfide SE membranes. [ABSTRACT FROM AUTHOR]

The development of fast‐charging lithium‐ion batteries with high energy density is hindered by the sluggish Li+ transport and substantial polarization within graphite electrodes. Herein, this study proposes that the integrated design of liquid electrolyte and solid electrolyte, a dual‐phase electrolyte (DP‐electrolyte), can facilitate Li+ transport within a thick electrode. A 3D Li3PS4 (LPS) network is constructed within the graphite electrode to form the LPS/graphite electrode. This is achieved through the in situ conversion of the P4S16 into the LPS, a process introduced during the slurry processing. Both experimental findings and simulation outcomes indicate that this design mitigates the concentration polarization due to the improved Li+ transport capability with an overall high Li+ transference number within the electrode. With a high capacity of ≈3.1 mAh cm−2 attributed to the graphite electrode, the LiNi0.6Co0.2Mn0.2O2 (NCM622)||LPS/graphite cells demonstrate superior fast‐charging capability (4 C, 15 min, charging to ≈87.7%) and stable cycling performance (4 C, 700 cycles, ≈80% capacity retention). Furthermore, they exhibit commendable low‐temperature performance. The Ah‐level pouch cell achieves 87.5% recharge in 15 min with an energy density of ≈221.5 Wh kg−1. This work offers an alternative avenue for the advancement of fast‐charging lithium‐ion batteries with practical high energy density. [ABSTRACT FROM AUTHOR]

A detailed computational investigation was conducted to explore the dynamics of high-speed free slurry jets, with a focus on how variations in abrasive size and concentration affect their behavior. The study yielded several significant observations: Firstly, it was observed that slurry jets containing larger particles exhibited notably higher average velocities, attributed to their inherent self-similar characteristics. Specifically, at the far field of the jet, slurry jets with larger particle sizes demonstrated a 15% increase in velocity compared to those with smaller particles. Additionally, an analysis of turbulent intensity revealed that beyond a certain axial distance (x/D = 10), turbulence levels progressively increased. However, intriguingly, for slurry jets with a high concentration (Co = 15%), there was a notable decrease (28%) in turbulent intensity compared to water jets, indicating a complex interplay between particle size and concentration. Secondly, the study found that as the concentration of particles in the slurry jet increased, there was a corresponding rise in the bulk temperature of the jet. This phenomenon was primarily attributed to the heightened thermal conductivity resulting from the increased density of particles in the water. Furthermore, an examination of the Nusselt number revealed interesting trends. While the Nusselt number exhibited a peak near the nozzle exit, indicative of enhanced heat transfer in this region, it showed a decremental trend along the axial direction of the jet, attributable to jet divergence. In summary, the computational analysis provided valuable insights into the behavior of high-speed slurry jets, highlighting the intricate relationships between abrasive size, concentration, velocity distribution, and thermal characteristics. These findings contribute to a deeper understanding of slurry jet dynamics and have significant implications for various industrial applications. [ABSTRACT FROM AUTHOR]

Real-time Fe content monitoring in iron ore slurry is crucial for evaluating concentrate quality and enhancing mineral processing efficiency. Laser-induced breakdown spectroscopy (LIBS) is a promising technique for the online monitoring of elemental content at industrial sites. However, LIBS measurements are hampered by the matrix effect and the self-absorption effect, limiting the precision of linear analytical processes. To overcome this, we propose to introduce a nonlinear processing unit based on the S-transform to incorporate nonlinearity into the data analysis process. This approach integrates a feature selection unit based on the spectral distance variable selection method (SDVS), a nonlinear processing unit based on the S-transform (ST), and a partial least squares regression model (PLS). To demonstrate the improvement in accuracy achieved through nonlinear processing, a comparative analysis involving five models, Raw-PLS, SDVS-PLS, ST-PLS, SDVS-ANN, and SDVS-ST-PLS, is conducted. The results reveal a significant improvement in the performance of the SDVS-ST-PLS model, effectively facilitating the successful application of the LIBSlurry analyzer to the mineral flotation process. [ABSTRACT FROM AUTHOR]

In this study, Si powder was used as raw material, Si 3 N 4 powder as a diluent, Al 2 O 3 , MgO, Y 2 O 3, and La 2 O 3 as sintering additives to prepare Si 3 N 4 ceramic with excellent properties using gelcasting and reaction re-sintering method. When the solid content of the slurry is 57.3 %, the viscosity is less than 1 Pa · s during the gelcasting process. After the reaction re-sintering, the sintered body of Si 3 N 4 exhibited a bulk density of 3.15 ± 0.05 g/cm3, a relative density of 96 ± 1 %, open porosity of 5.7 %, bending strength of 610 ± 20 MPa, elastic modulus of 235 ± 10 GPa, thermal conductivity of 48 ± 5 W/(m·K), and a linear shrinkage rate of 12–13 %. These parameters indicate that Si 3 N 4 ceramic possesses outstanding mechanical properties and thermal conductivity. [ABSTRACT FROM AUTHOR]

Fault fracture zones are rock formations commonly encountered in submarine tunnels, and the diffusion mechanism of slurry in fault fracture zones has a crucial impact on submarine tunnel reinforcement. Based on the seepage equation of Bingham fluid, the tortuosity parameter, fractal theory, and variable viscosity equation are introduced to establish a spherical permeation grouting model of Bingham fluid considering the slurry diffusion path and viscosity time variability. The viscosity variation law with time of sulfur aluminate cement slurry under different seawater admixture conditions was tested, and the time-varying equation of viscosity of sulfur aluminate cement slurry was obtained by fitting. A set of fault fracture zone permeation grouting test system was developed, and a fault fracture zone grouting simulation test was carried out. The study shows that the diffusion distance calculated without considering the influence of slurry diffusion path and seawater is 1.63–1.91 times of the test value, which obviously overestimates the diffusion distance; the diffusion distance calculated with considering the influence of diffusion path and seawater is 1.06–1.35 times of the test value, which is in good agreement with the test value. The research results can provide some theoretical support for the design of grouting in seawater environment. [ABSTRACT FROM AUTHOR]

Tunnelling in complex geological strata is a challenging task that can affect the performance of shield machines and result in unexpected hazards. Therefore, extensive knowledge of unfavourable environments and shield operational parameters is essential for ensuring successful and safe tunnelling. This study aims to analyse the geological and hydrological conditions of the Chunfeng Tunnel and present the key construction technologies of a large slurry shield machine when crossing complex strata. To this end, attempts were made to (i) discuss the geological and environmental challenges encountered during the tunnelling process and present some early interpretations based on the database information, (ii) analyse the factors affecting tunnel performance and simulate the ground surface settlement along the tunnel alignment and (iii) discuss the countermeasures under adverse ground conditions and propose future directions. The results revealed that tunnelling in fault zones with soft upper and hard lower strata led to severe wear of disc cutters and controlling the tunnelling parameters could provide a suitable method for adjusting the construction process. This study leveraged extensive experience gained during tunnelling using a large slurry shield machine, with special emphasis on mixed ground strata, by providing valuable insights and suggested responses for effective tunnelling strategies. [ABSTRACT FROM AUTHOR]

This study was accomplished in oil drilling wells located in the Mishrif and Mauddud carbonate formations and in the Zubair sandstone formation to ensure safer, efficient, and economical cementing operations, a better bond between the cement, casing, and formation, and a better isolation between the zones. Moreover, it was also undertaken to obtain competitive cement at the shoe. The study developed a cement slurry programme of 1.55 lead and 1.9 SG tail slurry for both the primary and secondary stages in well WQ1-XX0, as well as a new programme for the wells that would follow (the same primary stage, and 1.45 and 1.75 SG for the secondary stage), so as to improve the casing and cementing stability and reduce costs. The results indicated that well problems were gradually reduced in wells WQ1-XX1 and WQ1-XX2 and were entirely eradicated in well WQ1-XX3. The reduction in cement cost was 62% (from 0.756 to 0.47 barrels per metre), and the cement shows good bonding at the top of productive formations (Mishrif, Mauddud, and Zubair). The problems and costs in the Zubair sandstone and Mauddud carbonate formations were higher than in the Mishrif formation, and the programme adopted would prove to overcome them all. The lightweight high-performance slurry, with a specific gravity of 1.45, achieved the objectives of liner cementing in the Mishrif wells without involving any losses. [ABSTRACT FROM AUTHOR]

Ceramic slurry is the raw material used in stereolithography, and its performance determines the printing quality. Rheological behavior, one of the most important physical factors in stereolithography, is critical in ceramic printing, significantly affecting the flow, spreading, and printing processes. The rheological behavior of SiO2 slurry used in stereolithography technology is investigated in the current research using different powder diameters and temperatures. The results present the apparent non-Newtonian behavior. The yielding characteristics occur in all cases. For single-powder cases, the viscosity decreases when the powder diameter is increased. When the nano-sized and micro-sized powders are mixed in different proportions, a more significant proportion of micron-sized powders will decrease the viscosity. With an increase in the nano-sized powders, the slurry exhibits the shear thinning behavior; otherwise, the shear thickening behavior is observed. Thus, the prediction model is built based on the use of the pelican optimization algorithm-deep extreme learning machine (POA-DELM), and the model in then compared with the fitted and traditional models to validate the effectiveness of the method. A more accurate viscosity prediction model will contribute to better fluid dynamic simulation in future work. [ABSTRACT FROM AUTHOR]

In recent years, the recycling and reutilization of shield tunneling residues (STR) have received extensive attention in underground engineering. To optimize the method of resource utilization of STR, this paper introduces a replacement method of STR slurry. The STR are incorporated into concrete and prepared as STR concrete (STRC) using a coarse and fine aggregate shell production process. By optimizing the mixing method of STR slurry, we obtained the best mixing process, and studied the influence of STR dosage and water–binder ratio (w/b) on the compressive strength of STRC. The results revealed that the air-dried STR preliminarily crushed to about 15 mm can be used to prepare STRC by extending the mixing time of STR slurry. The compressive strength of the concrete significantly depends on the dosage of STR slurry. The strength decreases significantly with the increase of STR dosage, and the recommended dosage is about 10%. The influence of the w/b on compressive strength is similar to that of ordinary concrete. A predictive model for the compressive strength of STRC was established by analyzing the relationship between the dosage of STR, w/b , age, and the strength of STRC. [ABSTRACT FROM AUTHOR]

Hydration of MgO is a potential technology for economically preparing Mg(OH)2 slurry. Understanding the rheological behavior evolution of the slurry during MgO hydration, particularly in the presence of hydration agent, is essential for better control of the hydrated Mg(OH)2 slurry's rheology. In this work, Mg(OH)2 slurry was prepared by hydrating MgO in the presence of glycine. The effect of glycine on the rheological behavior of the hydrated Mg(OH)2 slurry have been investigated by means of viscosity, shear stress, sedimentation measurements, particle size distribution, 1H nuclear magnetic resonance relaxometry and zeta potential. Results showed that shear thinning rheological slurry could be made by hydration at 80 °C for 1 h. The yield stress of the slurry is 27.49 ± 0.81 Pa, and no settling occurs within 7 days. Yet, in the absence of glycine, the structure of the slurry was unstable and easily settled even after 8 h of hydration. Glycine has multiple effects on the slurry's solid loading, particle morphology, particle size distribution, and zeta potential of the slurry. In addition, the neutral zwitterionic form of glycine may serve as an inter-particle lubricant, reducing viscosity. [ABSTRACT FROM AUTHOR]

Y 2 O 3 and CaO are ideal ceramic materials for precision casting of TiAl alloy, overcoming challenges associated with intricate component removal, such as turbine blades, leveraging the stability of Y 2 O 3 and the water solubility of CaO. To address these challenges, we employed Isobam104 in a novel gel casting method, serving as both a dispersant and a gelling agent. This method enabled us to create a stable Y 2 O 3 –CaCO 3 slurry with high solid content (up to 55 vol%) and low viscosity (101.51 mPa·s at a shear rate of 10 s−1). Following sintering at 1500 °C for 2 h, Y 2 O 3 –CaO composite ceramics were produced. Surprisingly, two distinct characteristics of CaO were noted. One showed a rod-shaped morphology with high chemical reactivity crucial for water solubility, while the other displayed a flat-like feature, forming a well-maintained interface due to its coherent or semi-coherent matching relationship with Y 2 O 3 , thereby providing excellent hydration resistance. Ultimately, we acquired composite ceramics showcasing a 30-day "shelf life" alongside exceptional water solubility. This establishes the theoretical groundwork for storing and employing soluble ceramic cores in the precision casting of TiAl alloy. [ABSTRACT FROM AUTHOR]