Basic Material Characteristics Research Articles

The basic characteristics of paste backfill materials based on highly active mineral admixtures: Part I. Preliminary study on flow, mechanics, hydration and microscopic properties

The cost performance of backfill materials in coal mines has long limited the widespread use of backfill technology. Therefore, developing backfill materials that are both cost-effective and high-performing is a pressing scientific issue that requires immediate attention. This study proposes replacing ordinary Portland cement (OPC) with highly active mineral admixtures, such as mineral powder and limestone powder, to prepare a green, low-cost, and high-performance coal mine backfill material. The use of mineral admixtures can improve the performance of the backfill material while reducing its environmental impact. The proposed approach is cost-effective and environmentally friendly. The study employed experimental tests and microscopic characterization methods, such as the slump test, hydration heat test, uniaxial compressive strength test, and microstructure test, to clarify the synergistic reaction mechanism of highly active mineral admixture-based paste backfill material (HAM-PBM). This clarification is helpful in regulating the macroscopic properties of hardened paste. The results show that: (1) The rheological properties of fresh HAM-PBM slurry are consistent with the Herschel-Bulkley model, and its fluidity meets the technical requirements for coal mine backfilling. The slump of fresh HAM-PBM slurry ranges from 140 to 145 mm, and the yield stress ranges from 3.188 to 12.819 Pa. (2) Highly active mineral admixtures significantly affect the early hydration process of HAM-PBM. The parameters of the hydration characteristics during the initial dissolution stage, acceleration stage, deceleration stage, and stabilization stage gradually decrease, while the duration of the induction stage gradually increases. This confirms that the early hydration activity of mineral powder (MP) and limestone powder (LF) is lower than that of OPC. (3) The uniaxial compressive strength (UCS) of the MP series exhibits an "anti-hook" change pattern, while the UCS of the LF series shows a decreasing change pattern. The microstructure, including the number of hydration products, microscopic density, and other characteristics, follows the same change pattern as the UCS. (4) Based on the synergistic reaction mechanism of hardened slurry, it is recommended that MP replace a maximum of 10 % of OPC and LF replace a maximum of 5 % of OPC. The need for composite replacement of OPC with MP and LF is clarified, resulting in a cost-effective coal mine backfill material. This study has contributed to the national "double carbon" policy and the low-cost backfilling application of coal mines.

Towards liquid EPR dosimetry using nitroxides in aqueous solution.

Objective. Water-equivalent dosimeters are desirable for dosimetry in radiotherapy. The present work investigates basic characteristics of novel aqueous detector materials and presents a signal loss approach for electron paramagnetic resonance (EPR) dosimetry.Approach. The proposed principle is based on the radiation dose dependent annihilation of EPR active nitroxides (NO·) in aqueous solutions. Stable nitroxide radicals (3-Maleimido-2,2,5,5-tetramethyl-1-pyrrolidinyloxy (MmP), 3-Carbamoyl-2,2,5,5-tetramethyl-1-pyrrolidinyloxy (CmP)) in aqueous solutions containing dimethyl sulfoxide (DMSO) as an additive were filled in glass capillaries for irradiation and EPR readout. Radiation doses ranging from 1 to 64 Gy were applied with a clinical 6 MV flattening filter free photon beam. EPR readout was then performed with a X-band benchtop spectrometer. The dose response, temporal stability and reproducibility of the samples' EPR signal amplitudes as well as the influence of the nitroxide concentration between 10 and 160μM on the absolute signal loss were investigated using MmP. CmP was used to examine the dependence of the dose response on DMSO concentration between 0 and 10 vol%. An indirect effect model was fitted to the experimental data assuming irradiation induced radical reactions as the underlying mechanism.Main results. For an initial MmP concentration of 20μM, absolute EPR signal loss is linear up to a dose of 16 Gy with a yield G(-NO·) of approximately 0.4μmol J-1. Within five weeks upon sample irradiation to doses between 0 and 32 Gy relative EPR signal fluctuations were on average (126 readouts) below 1% (1σ). For c(MmP) ≥ 20μM, absolute signal loss is only weakly dependent on c(MmP), whereas it increases strongly with increasing c(DMSO) in the range 0-5 vol%. An indirect effect model is applicable to describe the reaction mechanism resulting in the observed dose response curve.Significance. Liquids consisting of nitroxides in aqueous solution and small amounts of DMSO (2 vol%) show promising basic characteristics for application as water-equivalent EPR dosimeter materials in radiotherapy. The EPR signal loss is based on an indirect effect mediated by diffusing radicals originating from the radiolysis of the water/DMSO mixture.

Numerical Equivalent Acoustic Material for Air-Filled Porous Absorption Simulations in Finite Different Time Domain Methods: Design and Comparison

Extracting the microscopic parameters of a porous material is a complex task, and attempts have been made to develop models that can simulate their characteristics, gathering the least amount of information possible. As a case in point, tests to evaluate macroscopic behaviors such as tortuosity, which depends directly on the microscopic fluid velocities, are highly susceptible to generate errors if the precision of the measurement devices is not correct, and the same goes for the other parameters. For this reason, in this paper, a sound propagation model in porous materials with a rigid frame is presented based on a local theory, which tries to simplify, even more, the way to obtain the basic characteristics of porous materials, such as their absorption coefficient at normal and random incidence, and their normal surface impedance. The proposed linearized equivalent fluid model presents four phenomenological coefficients, which characterize acoustic propagation trough the material. Their values are obtained from the material thickness and a measurement in an impedance tube following the ISO 10534 standard. Thus, what is only required is the measured absorption coefficient, either on one third or one octave bands, to fully represent the acoustic behavior in the finite different in time domain (FDTD) method. The model has been simulated with FDTD in porous and fibrous kernels, and the results show a strong agreement with the laboratory measurements and with the analytical results calculated with well-established semi-phenomenological models.

How Activated Carbon Can Help You—Processes, Properties and Technological Applications

Activated carbon has many potential applications in both the liquid and gas phases. How activated carbon can help practitioners in industry is explained. This practical teaching article introduces the first part of the special issue on Recent Advances in Applied Activated Carbon Research by providing a handbook explaining the basic applications, technologies, processes, methods and material characteristics to readers from different backgrounds. The aim is to improve the knowledge and understanding of the subject of activated carbon for non-adsorption experts such as professionals in industry. Therefore, it is written in a comprehensible manner and dispenses with detailed explanations to complex processes and many background references. This handbook does not claim to be complete and concentrates only on the areas that are of practical relevance for most activated carbon applications. Activated carbon and its activation and reactivation are initially explained. Adsorption and relevant processes are outlined. The mechanical, chemical and adsorption properties of activated carbon are explained. The heart of the handbook outlines key application technologies. Other carbonaceous adsorbents are only introduced briefly. The content of the second part of the special issue is highlighted at the end.

Remediation of lead-contaminated groundwater by oyster shell powder-peanut shell biochar mixture.

Groundwater pollution caused by lead ions has become a widespread issue worldwide due to the ever-increasing development of industrial activities. Such pollution poses significant threats to both humans and the environment. Oyster shell powder-peanut shell biochar mixture (OSP-PSB mixture) was used for lead-contaminated groundwater treatment by permeable reactive barrier (PRB) technology. Basic characteristics of materials proved that OSP-PSB mixture has good adsorption properties; OSP with particle sizes ranging from 0.85 to 1.18mm was used in this research; according to engineering and adsorption characteristics, OSP-PSB mixture (5:1) showed excellent permeability (4.35 × 10-4cm/s) and lead adsorption capacity(27mg/g); long-term permeability of the OSP-PSB mixture slightly decreased over time and met the permeability requirements for PRB; the removal mechanisms of lead ions by OSP-PSB mixture include precipitation, surface complexation, ion exchange, and physical adsorption. The experiment results showed that the OSP-PSB mixture fulfills the actual project requirements of PRB.

STUDY ON THE VISCOELASTOPLASTIC PROPERTIES OF POLYTETRAFLUOROETHYLENE AND NANOCOMPOSITES WITH INCREASED WEAR RESISTANCE BASED ON IT. PART 1. MATERIALS, TEST PROGRAMS AND BASIC PROPERTIES

This is the first (introductory) article in a series of articles devoted to a comprehensive experimental study and modeling of the viscoelastoplastic properties of polytetrafluoroethylene and a number of composites with increased wear resistance based on it, obtained in recent years in the laboratories “Technology of Polymer Nanocomposites” and “Polymer Composites for the North” of the Ammosov North-Eastern Federal University by introducing layered silicates (mechanically activated kaolin and serpentine, magnesium spinel) and short basalt or carbon fibers as fillers. Data from quasi-static tensile tests of these materials under different loading programs are presented: a family of stress-strain curves (until failure) at different strain rates, loading and unloading curves at different strain rates, creep and recovery curves for different stress levels, etc. The basic scalar characteristics of materials are determined (instantaneous modulus, yield strength, stress and strain at failure depending on the loading rate, etc.), the influence of the composition and proportion of fillers on them, and their strain rate sensitivity are analyzed. After mechanical tests, changes in the microstructure of PTFE and composites with different filler contents in the destruction zones of the samples were studied using a scanning electron microscope. An initial analysis of the volume of test data accumulated over 2 years revealed high deformability of materials, pronounced hereditary properties, the ability of materials to creep (flow) under constant load and accumulate irreversible (plastic) deformation, very high strain rate sensitivity, a strong influence of small amounts of fillers on the structure and mechanical properties. A more detailed presentation of the entire volume of test data and effects found, a systematic study of the viscoelastoplastic properties of these materials with different filler contents and their detailed comparative analysis as well as detection of connection with wear resistance are the topics of subsequent articles in the series in 2023-2025.

Magneto-mechanical coupling effect of ferromagnetic materials: Test characteristics and theoretical model

The magneto-mechanical coupling effect of ferromagnetic materials is the result of macroscopic influence of mechanical properties on magnetic properties under the combined action of stress field and applied magnetic field, which essentially can be attributed to the change of material properties caused by the transformation of microscopic magnetic domain structures. The effect of applied magnetic field is mainly manifested as the change of magnetic moment cluster (direction and size) inside microscopic magnetic domain; The stress field mainly causes the movement and rotation of the domain walls inside the ferromagnetic material, and further causes the change of magnetic moment cluster. Taking Q235 low carbon steel as an example, the effects of tensile stress σt on some important magnetic parameters of ferromagnetic materials under different excitation intensities (i.e., H0), such as the maximum value of applied magnetic field Hmax, intrinsic coercive field Hcj, hysteresis loss power per unit volume ph and anhysteretic magnetization Man, were obtained by setting macroscopic magneto-mechanical coupling test and fully considering the influence of demagnetizing field Hd (The standard ring specimen was used for demagnetization correction of the non-standard strip specimen). Meanwhile, the basic magnetization characteristics of ferromagnetic materials were discussed by introducing the basic magnetization curve F(H0, Ban) and considering the effect of σt as the equivalent stress field Hσ based on the theory of microscopic magnetic domain and the principle of thermodynamic. In the range of 635.4 A/m ≤ H0 ≤ 928.6 A/m and 0 MPa ≤ σt ≤ 350 MPa, the theoretical calculation models Man(H0, σt) and Hσ(H0, σt) in the magneto-mechanical coupling effect were obtained, which are in good agreement with the experimental results.

Light‐Emitting Device Based on Amplified Spontaneous Emission

AbstractIn recent years, with the rapid development of military, optical communication, biological imaging, and other fields, practical engineering applications such as fiber‐optic gyroscope, wavelength division multiplexing, and optical coherence tomography have put forward higher requirements on light sources. Amplified spontaneous emission (ASE) light source has become an excellent candidate due to its advantages such as suitable bandwidth, low coherence, and high power. Although the ASE light source is developed to a certain extent, there is still great room for improvement in the choice of gain medium and device structure. In order to accelerate the development and practical engineering application of ASE optoelectronic devices, it is of great significance to grasp the basic characteristics of the gain materials and the design of the device structure. In this review, the principle of the ASE effect and its difference with the generation of lasing are analyzed. Then, the optical gain properties of various gain materials, together with different structural types of electrically pumped ASE devices and their practical engineering applications, are summarized. Finally, the new ASE light‐emitting devices integrated with high‐gain materials and low‐cost structures are prospected to provide more ideas for their development.

Recent Advances in Biomass-Based Materials for Oil Spill Cleanup.

Oil spill on sea surfaces, which mainly produced by the oil leakage accident happened on tankers, offshore platforms, drilling rigs and wells, has bring irreversible damage to marine environments and ecosystems. Among various spill oil handling methods, using sorbents to absorb and recover spill oils is a perspective method because they are cost-effective and enable a high recovery and without secondary pollution to the ecosystem. Currently, sorbents based on biomass materials have aroused extensively attention thanks to their features of inexpensive, abundant, biodegradable, and sustainable. Herein, we comprehensively review the state-of-the-art development of biomass-based sorbents for spill oil cleanup in the recent five years. After briefly introducing the background, the basic theory and material characteristics for the separation of oil from water and the adsorption of oils is also presented. Various modification methods for biomass materials are summarized in section three. Section four discusses the recent progress of biomass as oil sorbents for oil spill cleanup, in which the emphasis is placed on the oil sorption capacity and the separation efficiency. Finally, the challenge and future development directions is outlined.

Predicting the Crystal Structure and Lattice Parameters of the Perovskite Materials via Different Machine Learning Models Based on Basic Atom Properties

Perovskite materials have high potential for the renewable energy sources such as solar PV cells, fuel cells, etc. Different structural distortions such as crystal structure and lattice parameters have a critical impact on the determination of the perovskite’s structure strength, stability, and overall performance of the materials in the applications. To improve the perovskite performance and accelerate the prediction of different structural distortions, few ML models have been established to predict the type of crystal structures and their lattice parameters using the basic atom characteristics of the perovskite materials. In this work, different ML models such as random forest (RF), support vector machine (SVM), neural network (NN), and genetic algorithm (GA) supported neural network (GA-NN) have been established, whereas support vector regression (SVR) and genetic algorithm-supported support vector regression (GA-SVR) models have been assessed for the prediction of the lattice parameters. The prediction model accuracy for the crystal structure classification is almost 88% in average for GA-NN whereas for the lattice constants regression model GA-SVR model gives ~95% in average which can be further improved by accumulating more robust datasets into the database. These ML models can be used as an alternative process to accelerate the development of finding out new perovskite material by providing valuable insight for the behaviours of the perovskite materials.

Calculation method for heat and mass transfer apparatuses with porous plastic contact devices

The development of effective contact devices for heat and mass transfer apparatuses, which allow increasing the intensity of heat and mass transfer processes, reducing the size and cost of technological equipment, is an important practical task of the modern food industry. In this regard, the high efficiency of foam contact devices is noted, due to the developed specific surface and low hydraulic resistance. In the course of the study, a general classification of these devices has been proposed; schematic diagrams of the constructions of foam packings and trays have been given, a brief comparative analysis of their application area has been carried out. The main stages of calculation of highly efficient heat and mass transfer apparatuses with cellular plastic contact devices, including the determination of the basic geometrical characteristics of cellular materials, packing height (plate thickness), number of packing sections (number of plates), hydraulic resistance of packed and plate apparatus, have been described in detail. An example of an engineering calculation of a distillation heat and mass transfer apparatus with packed and plate-shaped foam contact devices for the separation of a binary mixture "ethyl alcohol - water" has been considered. The results of the calculation are presented in tabular and graphical form and allow us to conclude that it is most expedient to use packed foam contact devices with smaller dimensions and hydraulic resistance.

Carbon Nanotube Coatings’ Role in Transparency, Mechanical Hardness, and Wetting Angle Increase

Among the different nanostructures involved in the improvement of material properties, carbon nanotubes occupy a specific place because of their small refractive index, extended surface, and large Young’s module, which can all provoke dramatic change in basic matrix material characteristics. Inorganic crystals, semiconductors, metals, conductive compounds, and some polymer structures whose surfaces are treated with carbon nanotubes demonstrate better features than the ones obtained before carbon nanotubes deposition. Thus, the areas of application for these unique nanostructure materials can be effectively extended, e.g., for optoelectronic use, in biomedicine, and display applications. In the current paper, the advantages of the laser-oriented deposition technique are shown in order to demonstrate how the main material parameters change drastically through the incorporation of carbon nanotubes.

Fracture resistance of 3D nano-architected lattice materials

Exploiting small scale material effects and structural topology, nano-architected lattices represent a recent novel class of mechanical metamaterials, which exhibit unprecedented combination of mechanical properties. Together with scarce resistance to fracture and catastrophic failure, understanding of the fracture characteristics and properties of 3D nano-architected lattices still represents a limiting factor for the design and realization of future engineering applications. Here, using a combination of in-situ tensile fracture experiments and finite element simulations, we first show the possibility to reach stable crack growth in nano-architected materials harnessing only the intrinsic plastic toughening mechanism. Exploring the effect of lattice topology on the fracture properties, we then demonstrate similar performance between the octet and 3D kagome architecture (along one direction). Based on the experimental and numerical results, a power-scaling law of normalized crack initiation toughness with relative density ρ¯ (i.e., fraction of material per unit volume) KIC/σyL∝ρ¯1.11, ρ¯1.17−1.27 is exhibited by the octet and 3D kagome topology, respectively, given the yield strength σy and the unit cell size L. Owing to the combination of the parent material’s size effect and plasticity (3D-printed photo-resist polymer), the fracture initiation toughness (considering σy=27MPa) of our octet nano-architected lattices is ∼ 8 times that of previously realized macroscopic octet titanium structures. After crack initiation, the two architectures manifest rising (in average ∼ 18%) fracture resistance curves (i.e., R-curves), without catastrophic failure. In addition, we find that the fracture toughness of architected lattices, measured by means of compact tension specimens, seems not to be dependent on the sample’s thickness, forcing to re-think the plain strain toughness definition for this class of materials. Our results uncover the basic fracture characteristics of 3D architected materials exhibiting stable crack growth, providing insights for the design of light-weight, tough materials, with implications for future macro-scaled structural applications.

Puckered Penta-like PdPX (X = O, S, Te) Semiconducting Nanosheets: First-Principles Study of the Mechanical, Electro-Optical, and Photocatalytic Properties.

The atomic, electronic, optical, and mechanical properties of penta-like two-dimensional PdPX (X = O, S, Te) nanosheets have been systematically investigated using density functional theory calculations. All three PdPX nanosheets exhibit dynamic and mechanical stability on the basis of an analysis of phonon dispersions and the Born criteria, respectively. The PdPX monolayers are found to be brittle structures. Our calculations demonstrate that the PdPX nanosheets exhibit semiconducting characteristics with indirect band gaps of 0.93 (1.99), 1.34 (2.11), and 0.74 (1.51) eV for X = O, S, Te, respectively, using the PBE (HSE06) functional, where PdPTe is the best material for visible-light photocatalytic water splitting. Our findings give important basic characteristics of penta-like two-dimensional PdPX materials and should motivate further theoretical and experimental investigations of these interesting materials.

Biodegradable Inks in Indirect Three-Dimensional Bioprinting for Tissue Vascularization.

Mature vasculature is important for the survival of bioengineered tissue constructs, both in vivo and in vitro; however, the fabrication of fully vascularized tissue constructs remains a great challenge in tissue engineering. Indirect three-dimensional (3D) bioprinting refers to a 3D printing technique that can rapidly fabricate scaffolds with controllable internal pores, cavities, and channels through the use of sacrificial molds. It has attracted much attention in recent years owing to its ability to create complex vascular network-like channels through thick tissue constructs while maintaining endothelial cell activity. Biodegradable materials play a crucial role in tissue engineering. Scaffolds made of biodegradable materials act as temporary templates, interact with cells, integrate with native tissues, and affect the results of tissue remodeling. Biodegradable ink selection, especially the choice of scaffold and sacrificial materials in indirect 3D bioprinting, has been the focus of several recent studies. The major objective of this review is to summarize the basic characteristics of biodegradable materials commonly used in indirect 3D bioprinting for vascularization, and to address recent advances in applying this technique to the vascularization of different tissues. Furthermore, the review describes how indirect 3D bioprinting creates blood vessels and vascularized tissue constructs by introducing the methodology and biodegradable ink selection. With the continuous improvement of biodegradable materials in the future, indirect 3D bioprinting will make further contributions to the development of this field.

Computational diffraction reveals long-range strains, distortions and disorder in molecular dynamics simulations of irradiated single crystals

Atomic-scale simulations, and in particular molecular dynamics (MD), are key assets to model the behavior of the structure of materials under the action of external stimuli, say temperature, strain or stress, irradiation, etc. Despite the widespread use of MD in condensed matter science, some basic material characteristics remain difficult to determine. This is, for instance, the case for the long-range strain tensor, and its root-mean-squared fluctuations, in disordered materials. In this work, computational diffraction is introduced as a fast and reliable structural characterization tool of atomic-scale simulation cells in the case of irradiated single crystals. In contrast to direct-space methods, computational diffraction operates in the reciprocal space and is therefore highly sensitive to long-range spatial correlations. With the example of irradiated UO2 single crystals, it is demonstrated that the normal strains, shear strains and rotations, as well as their root-mean-squared fluctuations (microstrain) and the atomic disorder, are straightforwardly and unambiguously determined. The methodology presented here has been developed with efficiency in mind, in order to be able to provide simple and reliable characterizations either operating in real time, in parallel with other analysis tools, or operating on very large data sets.

Improved quality and functional properties of Ti-6Al-4V ELI alloy for personalized orthopedic implants fabrication with EBM process

Understanding the manufacturing process parameters and their correlation with final product functional properties is needed to ensure performance in critical applications in the medical industry. This article presents the holistic procedure for verifying the quality of manufactured products, including the determination of basic material characteristics and strength parameters based on EBM (Electron Beam Melting) technology for the titanium alloy Ti-6Al-4V ELI. The aim of this study was to investigate the effects of the manufacturing and post-processing methods used, on the geometric accuracy, microstructure, mechanical and cytotoxic properties of additively manufactured parts, especially in the form of personalized jaw implants. The effect of Hot Isostatic Pressing (HIP) treatment on microstructure and properties is also taken into account. The EBM manufacturing process was developed and samples were built using three different orientations: 0° (horizontally), 45° (diagonally), and 90° (vertically). The novel results are systematically presented and discussed beginning from the selection of process parameters, sample manufacturing, wide microstructural characterization, determination of static mechanical properties as well as geometric accuracy, and quality control verification depending on the manufacturing process and the post-processing methods used. The conducted research allowed for the presentation of the entire process chain of the EBM manufactured medical implant made of high-purity titanium alloy (Ti-6Al-4V ELI), thus filling the scientific gaps related to the selective presentation and discussion of research results published in the literature on the subject.

Identification of Elastic Characteristics of Unidirectional CFRP under Off-Axis Tension Taking into Account the Rates of Loading

Polymer-based fiber composites have a number of unique physical and mechanical properties and are widely used in the design of structural elements in rocket and space engineering. However, along with the high characteristics of strength and rigidity, there is a noticeable anisotropy of properties which contributes to occurrence and development of damage leading to degradation of the load bearing capacity of structures and their premature destruction. Along with development of micromechanical and phenomenological models, an important place has the procedure for identifying the basic characteristics of composite materials. Such characteristics, in particular, include those of layer elasticity which are usually used when designing structures. However, even such characteristics depend on the loading conditions and for their identification, computational methods based on statistical analysis should be used. This paper attempts to identify the elastic characteristics based on test results of unidirectional carbon plastic with AS4 carbon fibers and polyetheretherketone thermoplastic matrix. For identification, the least squares method was used for samples tested at off-axis angles of 0, 10, 30, 45, 60 and 90 ° and different values of strain rates.

Asphalt Pavement Cold Recycling and Basic Characteristics of RAP Materials and Their Application

Asphalt Pavement Cold Recycling and Basic Characteristics of RAP Materials and Their Application

Enhancement of mechanical and corrosion protection properties of different substrates after friction surfacing: A concise review

Friction surfacing (FS) is a thermo-mechanical surface modification technique that can enhance the microstructure, mechanical, and tribological characteristics of a surface. The combined action of friction between the substrate and the consumable rod, as well as viscoplastic deformation in the coating and substrate materials, produces heat. FS was first restricted to the processing of soft materials such as aluminium and magnesium alloys. However, it is now gradually being introduced for hard materials and alloys also. Microstructural characteristics, tribological properties, mechanical properties and erosion-corrosion resistance are some of the processed surface qualities that can be enhanced with FS without affecting the basic material characteristics. According to the literatures, tool rotational speed, substrate travel speed, and axial force are significant process factors that affect the processed surface performance. The purpose of this paper is to examine and emphasize the different process parameter impacts on the resulting microstructural, mechanical, corrosion and tribological characteristics, as well as current challenges and future prospects in FS.