Fragmentation Of Particles Research Articles

Experimental study on the engineering properties and failure mechanism of moraine in Southeast Tibet under freeze–thaw cycles conditions

The effect of freeze–thaw cycles (FTCs) is a prevalent hydrothermal phenomenon in seasonal permafrost regions, significantly affecting the micro and engineering properties of moraine. This study investigates the engineering properties and failure mechanisms of moraine induced by FTCs, using samples with varying dry densities subjected to 0–20 FTCs. The permeability characteristics, particle breakage characteristics, elastic modulus, stress–strain curve, excess pore water pressure, peak friction angle, and critical state line characteristics of the moraine were analyzed before and after the FTCs, and the microscopic failure mechanism of moraine induced by FTCs was revealed. The test results show a degradation in the engineering properties of moraine induced by FTCs, exhibiting the greater the dry density the more obvious the damage to the engineering properties of the moraine. In addition, the particle fragmentation and fine particle aggregation caused by the FTCs changed the distribution, shape, arrangement, and particle intercontact patterns, which revealed the failure mechanism of moraine induced by FTCs. The correlation analysis between the shear strength index and microstructural parameters demonstrated that the particle arrangement has the greatest effect on the peak friction angle and particle shape has the greatest effect on the critical state line of moraine under the FTCs conditions. The findings offer experimental evidence and theoretical support for preventing and resolving geological risks and engineering project problems resulting from the deterioration of moraine shear strength during FTCs in the alpine mountain region.

Repose angle prediction of railway ballast based on Hopper Flow Test and PCA-Stacking ensemble learning method

The deterioration of track ballast is mainly reflected in the fragmentation of ballast particles and the evolution of grading. The repose angle of the ballast is the internal friction angle, reflecting the shear strength of the track ballast. The angle of repose of 158 ballast samples with varying gradation parameters was tested by conducting hopper flow tests on ballast particles. Then, based on this database, a stacking ensemble regressor-based principal component analysis (PCA) was proposed for the repose angle prediction. The data are first processed by PCA and then randomized into the train (80%) and test (20%) data. Besides stacking ensemble regressor, five different individual regressors, including support vector regressor, k-nearest neighbors, random forest, gradient boosting decision tree, and adaptive boosting, are compared and analyzed. The results indicate that the stacking ensemble regressor performs better than single regressors and demonstrates enhanced robustness and generalization capabilities. Additionally, the Effect of the number of principal component indicators on the prediction accuracy is determined, and the difference in stacking ensemble prediction performance with and without PCA is discussed. Finally, a computer prediction system for ballast repose angle was developed to make the proposed stacking ensemble regressor directly applicable to the railroad construction site. This model can be used in practical track maintenance decisions, whereby the ballast gradation can facilitate rapid assessment of the angle of repose.

Structure refinement and performance balance of high-strength aluminum alloys using an improved thermomechanical treatment process

The microstructure of 7A85 aluminum alloy forgings often contains coarse second-phase particles and grains. To improve the microstructures and balance the properties, we used an enhanced thermomechanical treatment process that included multiaxial hot forging, multiaxial cryoforging (MACF), and three-step aging treatment. We thoroughly investigated the effects of MACF with 1–3 passes on the evolution of microstructure, three-dimensional (3D) mechanical properties at the center and edge, fracture toughness, and corrosion resistance of the alloy. Our findings revealed that multiaxial hot forging had a limited ability to crush the coarse second-phase particles. However, the higher flow stress and compound brittleness of MACF resulted in a significant increase in particle fragmentation and driving force for precipitation. Additionally, under MACF, massive dislocations proliferated due to the inhibition of dynamic recovery, forming large orientation gradient regions, which promote static recrystallization and grain refinement during solution treatment. As the number of MACF passes increased from one to three, the effect of particle crushing initially increased and then plateaued, the 3D grain sizes first decreased and then slightly increased, and the spacing of grain boundary precipitates (GBPs) increased. The dense and uniform precipitates, finest equiaxed grains, a low fraction of coarse particles, and large GBP spacing in MACF2 resulted in the higher strength, highest elongation with minimal anisotropy, superior fracture toughness, and enhanced corrosion resistance. Ultimately, MACF2 demonstrated the best overall performance and good homogeneity, with an average 3D ultimate tensile strength, average 3D yield strength, average 3D elongation, and fracture toughness at the center of 548 MPa, 476 MPa, 13.4%, and 42.5 MPa m1/2, respectively. These values were respectively 4.2%, 1.9%, 50.6%, and 13.9% higher than those of the uncompressed sample.

Analysis of thermomechanical coupled accelerated aging of HTPB propellants

AbstractThis study employed macroscopic uniaxial compression tests at low and medium strain rates, coupled with microscopic electron microscopy, to extensively analyse the impact of thermomechanical coupled aging on the accelerated aging of Hydroxyl‐terminated Polybutadiene (HTPB) propellants, contrasting it with the effects of isolated factors such as heat and dynamic reciprocating force. Results indicate that at various environmental temperatures (323 K, 343 K, and 363 K), thermomechanical coupled aging more significantly affects HTPB propellants than isolated factors. This effect is macroscopically evident in increased ease of deformation, permanent deformation during aging, continual increase in dissipated energy, and a decrease in average stress and ultimate strain post‐aging. Microscopically, the effect predominantly arises from the interplay between matrix thermal degradation and particle fragmentation, which rapidly accumulate and substantially impact the material's macroscopic mechanical properties. Furthermore, as the aging temperature rises, the alterations in both macroscopic mechanical properties and microscopic morphology of HTPB propellants become more pronounced. However, overly high temperatures may swiftly result in substantial material performance deterioration. Consequently, while elevating temperature effectively accelerates thermomechanical aging, the potential adverse effects on material performance must be judiciously considered. This underscores the necessity of balancing temperature regulation with aging efficiency enhancement in HTPB propellants to ensure effective control and quantitative assessment of the aging process, while minimizing material degradation.

Poly(vinyl alcohol) gels cross-linked by boric acid for radiation protection of astronauts

Gels are soft materials composed of hydrophilic polymers cross-linked in water by physical or chemical bonds. Due to their lightweight and water-rich nature, these materials find application in various fields, including the space environment, for radiation protection purposes. In fact, thanks to their high hydrogen content, gels exhibit significant radiation stopping power, resulting in reduced fragmentation of incident particles. This suggests their potential utility in shielding electronic devices and safeguarding astronauts’ health. In this work, cross-linked gels based on poly(vinyl alcohol) (PVA) and boric acid (BA) were fabricated and their properties were investigated using different experimental and modeling techniques. The effect of parameters, such as time and temperature, used for fabricating the PVA/BA gels is assessed. Fourier transform infrared spectroscopy (FTIR) was employed to evaluate the ability of BA to form hybrid interpolymeric bonds with PVA macromolecules. To understand the thermo-mechanical properties and viscoelastic behavior of these gels, dynamic mechanical analysis (DMA) in compression mode was performed. The shielding properties were evaluated in different space radiation environments considering galactic cosmic rays, solar particle events, and low earth orbit radiation using deterministic transport codes. The High charge (Z) and Energy TRaNsport (HZETRN) code was employed to create different cross sections as first output for the selected materials, and then, propagate and transport the ionizing radiation inside the materials. The results highlight several advantages of PVA/BA gels fabricated at room temperature without heat treatments. Firstly, the incorporation of BA allows for a slight increase in water content compared to gels produced without the crosslinker. Additionally, an examination of elastic moduli reveals improved mechanical properties exhibiting approximately twice the elastic modulus of PVA gels. Moreover, the analysis of dosimetry quantities suggests that the radiation protection effectiveness of these gels is comparable to that of pure water, while heat-treated PVA/BA gels exhibit a reduced water content resulting in decreased shielding properties and decreased flexibility. Consequently, PVA/BA gels realized at room temperature appear to be the optimal material between PVA gels and the heat-treated counterparts, making them well-suited for integration into astronaut personal protective equipment.

Use of metal-tagged environmentally representative micro- and nanoplastic particles to investigate transport and retention through porous media using single particle ICP-MS

Microplastics and nanoplastics (collectively, MNPs) are increasingly entering soils, with potential adverse impacts to agriculture and groundwater. Environmental detection, characterization, and quantification of MNPs is difficult and subject to artifacts, often requiring labor-intensive separation from environmental matrices. These analytical challenges make it difficult to conduct experiments investigating specific MNP characteristics influencing their transport and fate, particularly when examining multiple plastic types at low concentrations. By synthesizing a suite of metal-tagged polymers, which are cryomilled to create polydisperse fragmented particle suspensions, single particle ICP-MS (spICP-MS) can be used to quantify MNP particle size and concentration in controlled fate and transport studies. Use of unique metal-polymer pairs enables accurate, simultaneous analysis of multiple MNP types which can be used to track total particle transport and retention within a variety of environmental matrices. This was demonstrated using saturated sand column transport experiments to quantify the movement of two plastics having different properties: tin-tagged polystyrene (Sn-PS) and tantalum-tagged polyvinylpyrrolidone (Ta-PVP). The behavior of these polydisperse, fragmented MNPs was compared to that of fluorescent, carboxylated monodisperse PS spherical microspheres (Fl-PS). Mobility of all MNP types increased with decreasing particle size, and hydrophilic Ta-PVP particles migrated more effectively than the hydrophobic Sn-PS particles. Furthermore, the addition of humic acid (HA) to the carrier solution increased the colloidal stability of both metal-tagged MNP suspensions, resulting in much greater elution from the column than in HA-free deionized water or moderately- hard water (ionic strength = 5mM). This combination of particle synthesis and spICP-MS analysis provides insights into the transport of MNP having physical properties that are representative of environmental MNPs and opens up a broad range of applications for study of MNP environmental fate and transport.

Oxidation-induced variations in the physical and fragmentation characteristics of exhaust soot from DMC-diesel blend: Effect of NO presence in the air atmosphere

This study investigated the changes in physical properties (including morphology, primary particle diameter, fractal dimension, and nanostructure) and fragmentation characteristics of exhaust soot from a modern direct injection diesel engine fueled with diesel (D100) and its blend with 7 vol% of dimethyl carbonate (DMC7) during oxidation processes in air and air-NO atmospheres. Soot particles (D100 soot and DMC7 soot) with specific oxidation degrees (0%, 20%, 50%, and 80%) were produced using a thermogravimetric analyzer, then applied to a high-resolution transmission electron microscopy to generate images. The results exhibited that the morphology for D100 soot and DMC7 soot transformed similarly through oxidation, experiencing an increase in fractal dimension, and a decrease in primary particle diameter, while the introduction of NO to the air accelerated these transformations. Additionally, the nanostructure of both soot particles was gradually ordered through oxidation, as evidenced by longer fringe length, narrower separation distance, and lower tortuosity, while DMC7 soot showed lower order degree compared to D100 soot. Interestingly, the ordering processes of soot nanostructure were decelerated as NO was involved in the oxidation process. Furthermore, the aggregate fragmentation rate for both soot particles declined over the oxidation process, while the possibility for primary particle fragmentation increased overall. Moreover, DMC7 soot exhibited significantly lower aggregate fragmentation rate and higher possibility for primary particle fragmentation than D100 soot at the same oxidation stage. This suggests that DMC7 soot is more susceptible to internal oxidation compared to D100 soot. Furthermore, the presence of NO in the air promoted aggregate fragmentation, while reducing the possibility of primary particle fragmentation.

Toxic effects of fragmented polyethylene terephthalate particles on the marine rotifer Brachionus koreanus: Based on ingestion and egestion assay, in vivo toxicity test, and multi-omics analysis

Microplastics (MPs) are a major concern in marine ecosystem because MPs are persistent and ubiquitous in oceans and are easily consumed by marine biota. Although many studies have reported the toxicity of MPs to marine biota, the toxicity of environmentally relevant types of MPs is little understood. We investigated the toxic effects of fragmented polyethylene terephthalate (PET) MP, one of the most abundant MPs in the ocean, on the marine rotifer Brachionus koreanus at the individual and molecular level. No significant rotifer mortality was observed after exposure to PET MPs for 24 and 48 h. The ingestion and egestion assays showed that rotifers readily ingested PET MPs in the absence of food but not when food was supplied; thus, there were also no chronic effects of PET MPs. In contrast, intracellular reactive oxygen species levels and glutathione S-transferase activity in rotifers were significantly increased by PET MPs. Transcriptomic and metabolomic analyses revealed that genes and metabolites related to energy metabolism and immune processes were significantly affected by PET MPs in a concentration-dependent manner. Although acute toxicity of PET MPs was not observed, PET MPs are potentially toxic to the antioxidant system, immune system, and energy metabolism in rotifers.

Evaluation an anionic polyacrylamide flocculant with microblock structure in the hematite wastewater treatment: Characterization and flocculation performance

In this study, a template polymer with anionic microblock structure was successfully synthesized through ultrasonic initiated template copolymerization (USTP) by using sodium allylsulfonate (SAS) and acrylamide (AM) as monomers, poly diallyl dimethyl ammonium chloride (polyDADMAC) as template, and 2,2′-azobis [2-(2-imidazolin-2-yl) propane] dihydrochloride (VA-044) as initiator. The anionic polyacrylamide (APAM-T) flocculant was characterized by Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance spectroscopy (1H NMR), and scanning electron microscopy (SEM). Furthermore, the X-ray photoelectron spectroscopy (XPS) was conducted to measure the elemental composition. The results of XPS and 1H NMR spectroscopy analysis indicated the existence of anionic microblock structure in APAM-T. Besides, the copolymerization was revealed to follow the self-assembly mechanism by analyzing the association constant (KM). The flocculation performance was evaluated by turbidity and zeta potential in the flocculation tests. The results indicated that the APAM-T with microblock structure enhanced the charge neutralization and bridging adsorption capacity, thus improving the flocculation performance. In the floc particle size distribution and fragmentation and reflocculation experiments, the floc corresponding to APAM-T had the strongest regeneration ability after fragmentation, which further confirmed the criticality of the microblock structure in enhancing the flocculation performance. Compared with existing studies, this study not only demonstrated a novel synthesis method, but also found that the microblock structure could significantly improve its treatment efficiency and effectiveness, providing a new theoretical basis and practical application path for wastewater treatment technology.

Influence of magnetic field on electron beam-induced Coulomb explosion of gold microparticles in transmission electron microscopy

In this work we instigated the fragmentation of Au microparticles supported on a thin amorphous carbon film by irradiating them with a gradually convergent electron beam inside the Transmission Electron Microscope. This phenomenon has been generically labeled as “electron beam-induced fragmentation” or EBIF and its physical origin remains contested. On the one hand, EBIF has been primarily characterized as a consequence of beam-induced heating. On the other, EBIF has been attributed to beam-induced charging eventually leading to Coulomb explosion. To test the feasibility of the charging framework for EBIF, we instigated the fragmentation of Au particles under two different experimental conditions. First, with the magnetic objective lens of the microscope operating at full capacity, i.e. background magnetic field B=2 T, and with the magnetic objective lens switched off (Lorenz mode), i.e. B=0 T. We observe that the presence or absence of the magnetic field noticeably affects the critical current density at which EBIF occurs. This strongly suggests that magnetic field effects play a crucial role in instigating EBIF on the microparticles. The dependence of the value of the critical current density on the absence or presence of an ambient magnetic field cannot be accounted for by the beam-induced heating model. Consequently, this work presents robust experimental evidence suggesting that Coulomb explosion driven by electrostatic charging is the root cause of EBIF.

Experimental Study on the Mechanical Strength, Deformation Behavior and Infiltration Characteristics of Coral Sand

In this investigation, coral sand is presented as a sustainable substitute for conventional river and machine-manufactured sand. This study comprehensively investigated the macro-scale strength, deformation, and permeability characteristics of coral sand, alongside analyzing the mechanical behavior, deformation, and permeability under various conditions and in relation to distinct particle characteristics. It revealed that coral sand primarily consists of biotite and high-Mg calcite, featuring abundant internal pore space. Its compressive properties resemble clayey soils, displaying minimal unloading rebound and predominant plastic deformation during compression. In direct shear tests, the stress–strain relationship follows an approximate hyperbola, with no pronounced strain softening. Describing particle fragmentation in the process proves challenging, making indicators like internal friction angle less applicable in engineering. Triaxial tests indicate a rapid initial bias stress increase, followed by a gradual decrease post-stress peak, suggesting a strain softening phenomenon. As surrounding pressure rises, the axial strain needed to reach peak strength also increases. The permeability coefficient of coral sand correlates linearly with pore ratio increase, represented by 10e. The complex interaction of multiple factors influences the strength, deformation, and permeability of coral sand blown fill mixes, with specimen porosity having the greatest impact. The design and construction of high-weight foundation elements in coral sand blown fill projects should consider porosity effects.

A Discrete Element Model of High-Pressure Torsion Test to Assess the Effect of Particle Characteristics in the Interface

Abstract Sand particles have been used since the early stages of the railway industry to increase adhesion at the wheel–rail contact. However, there is a limited understanding of how sand particle characteristics affect the tribological performance of the wheel–rail contact. In this work, the high-pressure torsion test used as a small-scale simulation of the interface is numerically modeled using the discrete element method (DEM). The DEM model is then utilized to investigate the effect of different particle characteristics on the frictional performance of wheel–rail contact which can provide more insight into micromechanical observations. The effects of various particle characteristics including their size, their number, the number of fragments the particles break into, and the parameters defining the behavior of the bonds between particle fragments on the coefficient of traction (COT) are systematically investigated. Results show that, in dry contacts, the coefficient of traction decreases when the size or number of sand particles increases. This can be attributed to the formation of weak shear bands between the fragments. Further investigation is needed for wet- and leaf-contaminated contacts. It is also found that the COT is more sensitive to the stiffness of the bond between the fragments of a broken particle compared to the strength of the bond. A limiting value for bond strength was identified, beyond which the sand particles exhibited ductile behavior rather than the expected brittle fracture. The findings from this study can be useful for future research on adhesion management in wheel–rail contact and the modeling approach can be scaled up to the full contact.

Experimental Study on Tailings Deposition Distribution Pattern and Sedimentation Characteristics.

Tailings pond accidents frequently occur during an extended period, resulting in loss of life and property, wastage of resources, and environmental pollution. Relying on tailings pond engineering, this paper carried out sample particle fragmentation experiments and settling column experiments to explore the deposition distribution pattern of tailings in both horizontal and vertical directions as well as the impact of particle size distribution on the sedimentation stratification effect. The results show that the median particle size on the dry beach surface in the horizontal direction slowly decreased with the increase in the distance from the subdam. The particle size of tailings showed great fluctuations in the vertical direction, which gradually became finer with the increase in the depth overall. At the same time, saturated sedimentation experiments suggested the inconsistent variation rule with the field test, namely, coarse on the bottom and fine at the top, and the change in particle size greatly affected the tailing sedimentation stratification effect. With the increase in fine particle content in tailings, the appearance time of the water-sand interface was shortened to within 30 min, but the sedimentation and consolidation completion times were delayed to about 1400 min. The settling column results indicate that the increase in fine particle content gradually weakened the sedimentation stratification effect, and the sedimentation pattern transformed from independent sedimentation to floc-type average sedimentation, which led to the enhanced water-retaining property of the settled layer. This may lead to an increase in the saturation line and a decrease in the length of the dry beach, seriously affecting the safe operation of the tailings pond. The research results provide some theoretical guidance and basic data for analyzing the consolidation efficiency of tailings and the stability of the tailings pond.

An electro-mechanical contact model for particulate systems

This study presents an electro-mechanical contact model to investigate the electrical response within a particulate system under mechanical loading. The model considers the electrical resistance across particle-to-particle and particle-to-wall contacts by formulating bulk and contact resistances, separately. Hertz and Holm's models are utilised for the contact resistance in the overlapping region. The bulk resistance for a particle is estimated considering particle geometry transformations during the compression. The proposed electro-mechanical contact model is verified and validated against published analytical solutions and experimental data. Finally, the contact model is applied to simulate a high-pressure torsion test to investigate the influence of three different materials on the electrical conduction properties of the system after particle fragmentation. The intensity distributions of electric potential, current and resistance of the granular system are analysed at both particle and system scales. An electroactivity index is proposed for evaluating the contribution of each fragment sieve cut on the bulk electrical conduction behaviour.

4-way coupling CFD-DEM simulation of particle breakage and classification in a spiral jet mill: A critical analysis

Jet-milling is a particle engineering process widely adopted in industrial manufacturing to reduce the particle size of powders. Computational Fluid Dynamics simulations (CFD) coupled with Discrete Element Modelling (DEM) proved to be a valuable tool to tackle the complexity and the non-linearity of particle breakage and classification occurring in mills. To date however, they have been employed to address only single aspects of process design being unable to reproduce it completely. The coupled CFD-DEM simulations presented in this work are for the first time capable of simultaneously describe particle fragmentation, particle-gas interaction and classification. Through coarse-graining, realistic amounts of powder can be simulated allowing to demonstrate/study how the hold-up mass slows down the milling gas affecting classification and thus the milling performance. Bottlenecks/limitations of model and methodology are critically examined to understand what is currently preventing us from creating a digital twin of the milling process.

Insight of the evolution of structure and energy storage mechanism of (FeCoNiCrMn)3O4 spinel high entropy oxide in life-cycle span as lithium-ion battery anode

Recently, spinel high-entropy oxide (HEO) anode materials have garnered extensive attention for high-energy lithium-ion batteries due to their high specific capacity. Many studies have explored its energy storage mechanism, but few have paid attention to its characteristics in long cycle life. In this work, the whole life cycling performance of (FeCoNiCrMn)-HEO is presented and investigated for the first time. Distinct capacity trends are studied to divide the cycling life into three stages: activation, upgradation, and degradation. Ex situ morphological characterizations are conducted to reveal that the driving force of stage change is continuous particle fragmentation. As a result, refined particles promote conversion reaction reversibility and induce extra interfacial capacity, achieving 2831 mAh g−1 at 825 cycles. Density functional theory (DFT) calculations provide a deeper insight into the high entropy effect on the ultra-high extra interfacial capacity. However, continuous refinement brings about huge electrolyte interface-derived layers, which are also responsible for pre-decay and post-collapse. The view of the evolution of the lithium storage mechanism is explicitly presented and experimentally verified by high-energy ball milling and fluorinated vinyl carbonate (FEC). These above results can give practical solutions to design high specific capacity and long-life cycle stability HEO anode in the future.

Combined Effect of Particle Reinforcement and T6 Heat Treatment on the Compressive Deformation Behavior of an A357 Aluminum Alloy at Room Temperature and at 350 °C

Solid state sintering of cast aluminum powders by resistance heating sintering (RHS), also known as spark plasma sintering or field-assisted sintering technique, creates a very fine microstructure in the bulk material. This leads to high performance material properties with an improved strength and ductility compared to conventional production routes of the same alloys. In this study, the mechanical behavior of an RHS-sintered age-hardenable A357 (AlSi7Mg0.6) cast alloy and a SiCp/A357 aluminum matrix composite (AMC) was investigated. Aiming for high strength and good wear behavior in tribological applications, the AMC was reinforced with a high particle content (35 vol.%) of a coarse particle fraction (d50 = 21 µm). Afterwards, separated and combined effects of particle reinforcement and heat treatment were studied under compressive load both at room temperature and at 350 °C. At room temperature compression, the strengthening effect of precipitation hardening was about twice as high as that for the particle reinforcement, despite the high particle content. At elevated temperatures, the compressive deformation behavior was characterized by simultaneously occurring temperature-activated recovery, recrystallisation and precipitation processes. The occurrence and interaction of these processes was significantly affected by the initial material condition. Moreover, a rearrangement of the SiC reinforcement particles was detected after hot deformation. This rearrangement lead to a homogenized dispersion of the reinforcement phase without considerable particle fragmentation, which offers the potential for secondary thermo-mechanical processing of highly reinforced AMCs.

Experimental study on behaviors of lithium-ion cells experiencing internal short circuit and thermal runaway under nail penetration abuse condition

This work compared the macro-phenomenon, voltage response, surface temperature, mass loss and material characteristics of LiCoO2 (LCO), LiMn2O4 (LMO), Li(NixCoyMnz)O2 (NCM), LiFePO4 (LFP) cells with the same capacity under penetration tests. The tests provided an in-depth study on behaviors and properties of internal short circuit (ISC) and thermal runaway (TR). From the results, a feature was discovered that the parameters of different types of cells showed different tendencies when penetrated with a series of diameter nails, determined by cathode materials. The LFP cell experienced a slight ISC. Temperature rise rate and maximum temperature increased with larger diameter of nails. The NCM, LCO and LMO cells experienced a severe ISC. The maximum temperature of cells increased, however, the temperature rise rate reduced and macro-phenomena delayed and weakened with larger diameter of nails. For different type of cells, the order of ISC sensitivity was as follows: LCO > LMO > NCM > LFP. As state of charge (SOC) increased, the cells had a higher risk of TR, evidenced by higher surge current and temperature rise rate. The results of nail penetration tests at 100 % SOC indicated that the hazard of TR was arranged in the order of LCO > NCM > LMO > LFP. Due to the fragmentation of secondary particles during the extrusion of nail, the cathode composed of secondary particles suffered more damage than composed of primary particles. The research can provide support for the safety design of cells.

Microplastics in the Danube River and Its Main Tributaries—Ingestion by Freshwater Macroinvertebrates

This study was carried out at the Danube River and its tributaries during the Joint Danube Survey 4 (JDS4) expedition. Three freshwater benthic species were used to estimate the quantity of microplastics (MPs): Corbicula spp., Limnodrilus hoffmeisteri (Claparede, 1862), and Polypedilum nubeculosum (Meigen, 1804). Following the kick and sweep technique, individuals were sampled using a hand net or dredge. In order to estimate the number of MP particles/individual particles/g wet body mass, the body mass and total length of all specimens were measured. Alkaline (Corbicula spp. and L. hoffmaisteri) and enzymatic (P. nubeculosum) protocols were performed for tissue degradation. All samples were filtered through glass microfiber filters (mesh size 0.5 µm). The particles were photographed, measured, and counted. A total of 1904, 169, and 204 MPs were isolated from Corbicula spp., L. hoffmaisteri, and P. nubeculosum, respectively. To confirm the chemical composition of isolated MPs, a subsample of 46 particles of the fragmented particles from 14 sampling sites was analysed via µ-ATR-FTIR spectroscopy analysis. The particles were characterised as polycarbonate (PC), polyethylene terephthalate (PET), polypropylene–polyethylene copolymer (PP-PE), nylon (polyamide-PA) and cellophane, with the domination of PET.

Quasi-static and dynamic deformation of aluminum matrix composites reinforced by core-shell Al35Ti15Cu10Mn20Cr20 high-entropy alloy particulates

Core-shell structured particles are potential reinforcement agents for metal matrix composites. In this work, aluminum matrix composites reinforced with core-shell structured Al35Ti15Cu10Mn20Cr20 high-entropy alloy (HEA) particles were fabricated by spark plasma sintering (SPS) and high-temperature diffusion post-treatment. Dynamic compression behavior and adiabatic shear failure mechanism in the composites were investigated by split Hopkinson pressure bar (SHPB), scanning electron microscopy and transmission electron microscopy. Results showed that the shell thickness of the core-shell particles ranged from 0.4 to 1.6 μm, which were formed by thermal diffusion between HEA core and aluminum alloy. The 30 vol% (Al35Ti15Cu10Mn20Cr20)p/2024Al composite showed a high compressive strength (594 MPa) and strain-to-failure (26.7 %) under quasi-static compression, as well as a high flow stress (602 MPa) and strain-to-failure (45.3 %) under dynamic compression, which are superior to common ceramic particles reinforced Al matrix composites. The (Al35Ti15Cu10Mn20Cr20)p/Al composites with ∼20–40 vol% core-shell HEA particles failed as bulging, 45° shearing or splitting when compressed at ∼1000-3000 s−1. Micro-damages in these composites were due to microcracks originated from the HEA core, while propagation of cracks was effectively restrained by the shell. Deformation bands and phase transformation (melting of aluminum) were both observed in the composites under dynamic loads. Chain-shaped deformation bands were formed by the fragmentation and rearrangement of the core-shell particles, instead of the recrystallized structure of metal matrix in particle-reinforced Al matrix composites reported previously. The formation of molten Al phase transformation bands was owing to shear localization and significant adiabatic temperature rise under dynamic compression.