Changes In Structure Of Material Research Articles

Evaluation of Concrete Fatigue Damage with Elastic Wave-based Measurement Techniques

Fatigue damage is a progressive and permanent change in the internal material structure due to cyclic loading. The cyclic loads can be due to wind, waves, temperature variation, and traffic loads. Each cyclic load application introduces micro-damages that accumulate to induce failure. Detecting these micro-damages requires sensitive measuring techniques. Hence this research compares the sensitivity of different measuring techniques applied to fatigue experiments of concrete. The applied NDT are the passive acoustic emission technique (AET) and active ultrasonic measurements. In addition, linear variable differential transformers (LVDTs) are applied as a reference measurement. Accordingly in this research, cylindrical concrete samples are subjected to monotonic and cyclic Brazilian splitting tests. The cylinders are 100 mm in diameter and 150 mm in length. The cyclic load is applied to these samples with a loading frequency of 5 Hz. During the tests, the damage evolution is monitored with AET, ultrasonic measurements and LVDTs. There are eight AE sensors attached to the sample. The two LVDTs are positioned at the center of the sample's front and back side. Besides passively monitoring the acoustic emissions, the AET sensors are also used to do active ultrasonic measurements. The research reports the comparison conducted on the deformations and cracks measured with the LVDTs, the damage growth identified with the AET, and the change in the ultrasonic pulse velocity measurements. In addition, the study also presents the damage analysis capacity of the methods across different types of loading: monotonic, constant amplitude, and stepped fatigue loading. The comparison shows that combination of AET and ultrasonic velocity measurement is a sensitive indicator for damage growth.

Research on flexible piezoresistive sensors based on nanocomposite materials

As a core component, sensors play a crucial role in fields such as the Internet of Things, biomedicine, and artificial intelligence by converting physical information into electrical signals. With technological advancements, the demand for improved sensor performance and environmental adaptability has been increasing, driving progress in advanced materials, new structures, and refined processing technologies to enhance the efficiency of converting pressure signals into electrical signals. Flexible piezoresistive sensors are widely used due to their high sensitivity, good linear response, and fast response time. The performance of these sensors heavily depends on the microstructure of the materials, and traditional detection methods struggle to capture their dynamic changes. Therefore, developing in-situ characterization techniques to monitor changes in material structure and chemical properties in real-time is crucial for optimizing material performance. Additionally, integrated sensor systems that study signal acquisition, circuit interfaces, and signal processing, combined with artificial intelligence algorithms for data processing and analysis, not only improve system efficiency but also broaden their application range.

A Fluorine‐Free Binder with Organic–Inorganic Crosslinked Networks Enabling Structural Stability of Ni‐Rich Layered Cathodes in Lithium‐Ion Batteries

AbstractAlthough the high‐energy Ni‐rich layered cathodes suffer from undesirable surface reactions with the electrolyte, the polyvinylidene fluoride (PVDF) binder has a limitation on surface stabilization because of its weak affinity and low adhesion/cohesion. Here, it is demonstrated that the novel fluorine‐free and hydroxyl‐rich siloxane nanohybrid (SNH) binder can enhance the electrochemical performances of LiNi0.8Mn0.1Co0.1O2 cathode (NCM811) via successful surface stabilization. The high silanol content in the SNH binder enhances the affinity to both NCM811 and conductive agent, facilitating uniform electron/ion pathways with high mass loading, improved shear thinning, and superior mechanical properties. Moreover, the fluorine‐free organic‐inorganic hybrid structure prevents the dissolution of transition metals, active material structural changes, and electrolyte interaction, leading to greatly enhanced cyclability of the SNH‐based NCM811 electrode (≈81.9% in half‐cell; ≈87.82% in full‐cell after 200 cycles) compared to PVDF‐based NCM811 electrode (≈58.8% in half‐cell; ≈61.24% in full‐cell after 200 cycles). Various analyses also indicate that the application of the fluorine‐free SNH binder successfully stabilizes both the surface and bulk structure of the NCM811 cathode during charge/discharge. The binder design represents a straightforward yet highly effective approach to achieving remarkably prolonged cyclability in lithium‐ion batteries, surpassing the performance of other fluorine‐based or polymer‐based binders.

In Situ SEM/STEM Enabling a More Complete Understanding of Thermally Induced Structural Changes in Materials

In Situ SEM/STEM Enabling a More Complete Understanding of Thermally Induced Structural Changes in Materials

Bulk MgB2 Superconducting Materials: Technology, Properties, and Applications.

The intensive development of hydrogen technologies has made very promising applications of one of the cheapest and easily produced bulk MgB2-based superconductors. These materials are capable of operating effectively at liquid hydrogen temperatures (around 20 K) and are used as elements in various devices, such as magnets, magnetic bearings, fault current limiters, electrical motors, and generators. These applications require mechanically and chemically stable materials with high superconducting characteristics. This review considers the results of superconducting and structural property studies of MgB2-based bulk materials prepared under different pressure-temperature conditions using different promising methods: hot pressing (30 MPa), spark plasma sintering (16-96 MPa), and high quasi-hydrostatic pressures (2 GPa). Much attention has been paid to the study of the correlation between the manufacturing pressure-temperature conditions and superconducting characteristics. The influence of the amount and distribution of oxygen impurity and an excess of boron on superconducting characteristics is analyzed. The dependence of superconducting characteristics on the various additions and changes in material structure caused by these additions are discussed. It is shown that different production conditions and additions improve the superconducting MgB2 bulk properties for various ranges of temperature and magnetic fields, and the optimal technology may be selected according to the application requirements. We briefly discuss the possible applications of MgB2 superconductors in devices, such as fault current limiters and electric machines.

Analysis Of Increasing Lubricating Oil Temperature In Ship Diesel Generators

Abstract Auxiliary aircraft is a vital part of a ship that is needed as a power plant or generator. In order to avoid more heat, lubricating oil is needed in the form of a chemical substance, in the form of a liquid given between two moving objects to reduce friction, as a protective layer separating the two surfaces in contact. This is due to the operation of the diesel generator which occurs continuously and can cause friction and erosion of the moving parts. So that friction causes changes in material structure which over time can cause heat. However, this condition makes the lubricating oil temperature increase every hour. This qualitative research uses Primary and secondary data collection methods, with observation (field survey), interviews and library research. Based on the results of the analysis, the cause of the increase in lubricating oil temperature is due to the condition of the electromotor of the seawater cooling pump through the bypass faucet not according to the desired pressure, pump bearings have wear and pump gears, then the heat absorption of the L.O Cooler shelf is not optimal due to blockages in the capillary pipes. That the increase in the temperature of the diesel generator lubricating oil above 700 C and the pressure of 2 kg/cm2 during the machinist’s duty hours 00.00-04.00 LT is caused by the diesel generator auxiliary motor having an ineffective Lo Cooler heat absorption capacity, sea water cooling pressure that is less than normal and the presence of pipe connections that leak cooling pipes

The relationship between conctere composition and structural stability in case of fire

A series of disasters caused by fire have made engineers aware that understanding the consequences of fire is essential, as human lives depend on it, and it can also cause significant material damage. The structural integrity of structures during and after a fire, including their stability, can be better ensured if we accurately understand the effects of fire. Of course, the effects of fire do not always lead to significant damage, but in many cases they do. Fire protection is intended, on the one hand, to ensure that buildings remain stable under fire for a certain period, which is necessary to enable occupants to escape safely and, on the other hand, to minimize damage to building structures. The concrete composition, i.e., the structure's microstructure, significantly influences the stability of reinforced concrete structures in the event of fire or heat. In the case of concrete, in addition to changes in the internal material structure in the event of fire, spalling has also appeared recently, largely due to the denser concrete structure. In summary, the higher strength of concrete and the concomitant change in the test strength will lead to spalling, which will have a major impact on the stability of structures under fire. Both small-element (fiber efficiency, aggregate efficiency) and large-element tests have been carried out to verify this. The small-element tests were carried out in an electric furnace to monitor possible concrete surface delamination and strength loss. The small-element tests can be used to select concrete compositions for the large-element tests. Based on their experimental results, an increase in the fire resistance limit of a structural element can be achieved by reducing the delamination of the concrete surface when plastic fibers are added to the concrete. However, if a further increase in the fire resistance limit is required, a change in the type of cement or a modification of the supplementary material may be necessary to increase the residual strength value. Overall, the microstructure of concrete has a significant impact on the stability of structures in the event of a fire.

In Situ Transmission Electron Microscopy Methods for Lithium-Ion Batteries.

In situ Transmission Electron Microscopy (TEM) stands as an invaluable instrument for the real-time examination of the structural changes in materials. It features ultrahigh spatial resolution and powerful analytical capability, making it significantly versatile across diverse fields. Particularly in the realm of Lithium-Ion Batteries (LIBs), in situ TEM is extensively utilized for real-time analysis of phase transitions, degradation mechanisms, and the lithiation process during charging and discharging. This review aims to provide an overview of the latest advancements in in situ TEM applications for LIBs. Additionally, it compares the suitability and effectiveness of two techniques: the open cell technique and the liquid cell technique. The technical aspects of both the open cell and liquid cell techniques are introduced, followed by a comparison of their applications in cathodes, anodes, solid electrolyte interphase (SEI) formation, and lithium dendrite growth in LIBs. Lastly, the review concludes by stimulating discussions on possible future research trajectories that hold potential to expedite the progression of battery technology.

Tabular Two-Dimensional Correlation Analysis for Multifaceted Characterization Data.

We propose tabular two-dimensional correlation spectroscopy analysis for extracting features from multifaceted characterization data, essential for understanding material properties. This method visualizes similarities and phase lags in structural parameter changes through heatmaps, combining hierarchical clustering and asynchronous correlations. We applied the proposed method to data sets of carbon nanotube (CNT) films annealed at various temperatures and revealed the complexity of their hierarchical structures, which include elements such as voids, bundles, and amorphous carbon. Our analysis addresses the challenge of attempting to understand the sequence of structural changes, especially in multifaceted characterization data where 11 structural parameters derived from eight characterization methods interact with complex behavior. The results show how phase lags (asynchronous changes from stimuli), and parameter similarities can illuminate the sequence of structural changes in materials, providing insights into phenomena such as the removal of amorphous carbon and graphitization in annealed CNTs. This approach is beneficial even with limited data and holds promise for a wide range of material analyses, demonstrating its potential in elucidating complex material behaviors and properties.

Towards a low-cost solid oxide electrolyte based on local mineral

The demand for critical minerals is showing significant growth as a response to various applications in energy transition devices such as those involving solid oxide electrolytes. Thus, in the present work a dense and conductor material was prepared following appropriate sintering of a low-cost local natural mineral (NM). Comprehensive morphological, textural, and microstructural characterizations were carried out in order to study the densification of NM samples shaped as thin layers obtained by casting method using polyethylene oxide (PEO) as a plasticizer and distilled water. It was found that sintering at 1000 °C was enough to achieve densification without any change of material structure, as indicated by significant decrease of specific surface area and porosity. Furthermore, the effect of temperature on electrical conductivity was measured by impedance spectroscopy (IS) under dry air by increasing temperatures and total conductivity value at about 8.48 × 10−2 S cm−1 was reached at 950 °C. Such promising intrinsic electrical conductivity, in addition to appropriate material densification, paves the way for possible application of such an available and low-cost natural minerals as solid oxide electrolyte.

Analysis of the Strength Properties of Epoxy-Glass Composites Modified with the Addition of Rubber Recyclate Using Kolmogorov-Sinai Metric Entropy.

This paper presents the results of investigations of the mechanical properties of epoxy-glass composites with the addition of rubber recyclate. For the purposes of the study, seven variants of materials were designed and manufactured, which differed in terms of the percentage of recyclate content (3, 5 and 7%) and the way the recyclate was distributed in the composite (one, two and three layers with a constant share of 5%). Tests of comparative mechanical properties were carried out using a static tensile test. As a result of the conducted tests, the following values were obtained for all variants of materials: tensile strength (Rm), Young's modulus (E) and percentage relative strain ε. In addition, for a deeper analysis of the results obtained, statistical calculations of Kolgomorov-Sinai EK-S metric entropy were performed on the experimental data sets, which were then analyzed. The results of the analysis indicate that the application of metric entropy calculations EK-S can be helpful in identifying changes in the internal structure of the composite material that occur during its loading, and which do not manifest themselves in any other tangible way. The data obtained as a result of the research can be used to optimize production processes and to determine the further direction of development of epoxy-glass composites with the addition of rubber recyclate, while saving time and resources.

Enhanced electrochemical performance of ZnO@sulphur-doped carbon particles for use in supercapacitors

Here, the electrochemical performance of ZnO@sulphur-doped carbon particles from banana peels in three stages for use in supercapacitors was investigated. The first stage involves the production of activated carbon from banana peel by NaOH activation (BPAC). The second stage involves the production of sulphur-doped BPAC (BPAC-S) by sulphuric acid activation of the obtained BPAC sample. In the third stage, the ZnO-doped BPAC-S sample was produced by ZnO doping using hydrothermal process. The electrochemical performances of the obtained BPAC-S and ZnO-doped BPAC-S samples were investigated in supercapacitor application as an electrode material. The characterization of the obtained materials was performed by SEM, FTIR, XRD, EDS and nitrogen adsorption/desorption analyses. In particular, there are significant changes in the capacitive response with the changes in the porous structure of the composite material with the addition of ZnO. In supercapacitor applications, the electrochemical properties of these electrode materials were investigated by CV, high charge/discharge and EIS analyses. The maximum specific capacitances for the BPAC-S and ZnO-doped BPAC-S at 10 mA/g were 147.03 and 224.15 F/g.

Modelling of the impact of burnishing force on average surface roughness

As a result of the development of engineering technology, new opportunities and methods are constantly being developed to examine individual material structure changes, but most of these are impossible to implement on a low budget. Tests carried out with finite element simulations enable the optimization of machining processes and the reduction of experimental costs. The paper discusses the modelling of burnishing process that can effectively reduce surface roughness and the effect of burnishing force on average surface roughness. The machining is simulated using DEFORM-2D software, corresponding to the values of the experimental parameters (burnishing force, feed, speed) implemented in practice, allowing a comparative analysis of the material quality of low alloyed aluminium.

Sustainable fragrance release wax oil coating for wood substrate based on peppermint essential oil microcapsules

At present, odorous emissions from wood products are the main leading cause of perceived discomfort in indoor environments. The source control is the most effective way to reduce odorous emissions. Herein, this study aims to investigate the impact of peppermint essential oil microcapsules on the unpleasant odor emissions from wax oil coated wood products. In this paper, peppermint essential oil microcapsules were added to wax oil to endow wax oil-coated wood with continuous fragrance release. The results showed that the microcapsules prepared by the complex coacervation method with gelatin and gum arabic as the wall materials and peppermint essential oil as the core material had significant fragrance slow-release ability and improved thermal stability. Adding microcapsules to wood wax oil at a mass ratio of 10% has no significant effect on the quality of the paint film, but the presence of amino groups in the wall material of the microcapsules causes a significant color change of the finished wood. The release of aromatic odors in wax oil-coated wood is significantly prolonged. The main odorant compounds released in the early stage were terpenes with herbal, woody and balsamic flavor characteristics. The odor compounds released at a later stage are mainly alkanes, and the odor is expressed as waxy, herbal and woody. The dispersion of microcapsules in wood wax oil leads to changes in the pore structure of the wood wax oil finish material, which provides multiple pathways for the slow release of odor compounds.

Numerical investigation of a novel concrete-to-steel column splice in mixed structures in height

Buildings in which the type of structural material changes between their stories are referred to as mixed-in-height structures. Typically, these buildings have concrete structures in lower stories and steel structures in upper stories. Valuable investigations have been conducted on mixed-in-height structures to explore their seismic response and changes in structural natural period due to the sudden change in the lateral stiffness at transition level and mass irregularity, but scant attention has been given to the connection between steel and concrete structures at varying heights. Given the geometrical limitations of existing concrete structures, the dimensions of steel columns in supplementary stories must align with those of reinforced concrete columns. Consequently, building codes have not yet provided guidelines for proper connection details and effective load transfer from upper steel to lower concrete structures which is crucial due to the abrupt changes in stiffness and force transfer mechanisms in such splice connections. Thus, this study considers Numerical investigation on two full-scale laboratory tested specimens, with similar details but different axial loads, and numerical analysis of a new connection between a concrete and a steel column at the transition level. This research examines the aforementioned connection under two boundary conditions. Furthermore, after validating the numerical models with experimental specimens, axial load parameters, relative percentage of reinforcement to concrete area, and the force–displacement diagrams are presented. Finally, a numerical model of a three-story column in a frame is analyzed using finite element analysis under lateral load, and the sequence of plastic hinge formation is studied. The practicality and effectiveness of the proposed splice was verified herein. Furthermore, the average value of ductility (µ) was calculated to be 5.5, while exhibiting negligible overstrength factor (Ω). Similar response parameters were calculated for F-AL-R2 (43.2 kN/mm, 21.1 kN/mm) and F-AL-R3 (43.8 kN/mm, 22 kN/mm), indicating that the influence of increased rebar percentage diminishes at higher values. The analysis demonstrates that column connection failure did not occur, and the sequence of hinge formation was from top to bottom, validating the suitable performance of the proposed connection.

INVESTIGATION OF CRYOGENIC TREATED DRILL BIT

We look into brief introduction of cryogenic treatment. Our focus throughout the report is more on cryogenic treatment of tool steel and high speed steel. In metal forming industry tools are exposed to very complex and rough surface conditions, which are the result of different effects (mechanical, thermal and chemical) and thus require well defined mechanical properties. Different approaches are followed to increase the surface properties of tool steels. The surface hardening treatments of steel has shown significant improvement of various properties including wear and fatigue resistance. Cryogenic treatment is yet another approach acknowledged by some to extend the tool life of many cutting tools. We will describe the complete procedure and investigate the effects on the metallurgical changes in the tool steel. However real mechanisms behind the better performance of tools are still in doubt. Studies in the given references on cryogenically treated tool steel shows micro structural changes in material that can influence the tool life. However little is gained from the experimental results showing involvement of carbide precipitations. Cryogenic treatments of carbides has yet to be extensively studied. In this paper drill bits are treated with cryogenic method and to predict the hardness, wear strength and other results are analysing.

Alloy Crystal Structure and Volumetric Mass Density Analysis

Volumetric mass density and changes in crystal structure analysis of Sn-xBi alloy and Sn-xBi-yAl alloys have been conducted to enhance our understanding of these materials. The Sn-xBi alloy, with various compositions including Sn-0Bi, Sn-10Bi, Sn-30Bi, Sn-52Bi, and Sn-70Bi, and the Sn-xBi-yAl alloys, with compositions including Sn-52Bi-0.05Al, Sn-52Bi-0.11Al, Sn-52Bi-0.14Al, Sn-52Bi-0.19Al, and Sn-52Bi-0.25Al, were synthesized for this research. The selection of Sn-xBi-yAl compositions was based on the optimal composition of Sn-xBi alloys, specifically Sn-52Bi, which possesses the lowest melting point at 142.8°C. The determination of melting points was carried out using the Differential Scanning Calorimetry (DSC) method. Crystal structure characterization was accomplished using X-ray diffraction (XRD) techniques, with subsequent analysis performed through the Generalized Structure Analysis System (GSAS) method. These investigations are pivotal as they provide insights into the material properties and structural changes in Sn-xBi and Sn-xBi-yAl alloys, which have significant implications in various industrial applications and technological advancements. The results of this research are expected to contribute to the optimization of these alloy systems, leading to improved performance and potential innovations in materials science and engineering.

Effect of low current cold atmospheric plasma on grains surface structure and water absorption capacity

The use of preparatory electrophysical methods of influencing food raw materials is one of the main trends in the development of innovative processes and technologies in the food and processing industry. Based on the physical effect of electron emission from a thermal emission source, a cold atmospheric plasma (CAP) was obtained, which was successfully applied to the grain material. Physical characteristics and evolution of low-temperature atmospheric plasma were considered as the main methods of analysis of electrophysical effects. To assess the effect of low-temperature plasma on grain material, measurements of water absorption capacity and analysis of surface modification by electron scanning microscopy were carried out. It has been experimentally established that CAP treatment contributes to a more intensive process of water absorption due to changes in the surface structure of the grain material. The total duration of the process of water absorption of grain material after processing of CAP decreased by more than three times until the equilibrium moisture content was reached. Scanning electron microscopy has shown that the processing of CAP leads to the appearance of a fine-mesh structure of the surface of the grain material. The effect of CAP treatment leads to modification of the seed surface, which consists in the manifestation of a fine-meshed structure on the surface of the seeds. Taking into account the advantages of CAP technology, namely the absence of the need for vacuuming and short processing time, the technology has a high practical potential.

Experimental Investigation and Controllability Study of Electrochemical Actuators Based on Si/CNTs Composite Material

Abstract Electrochemical actuators can convert electrical energy into mechanical energy directly and have been applied widely. With a large volume expansion in the electrochemical reaction, silicon material demonstrates enormous potential in the manufacture of electrochemical actuators. Here, we propose a new electrochemical actuator based on Si/CNTs composite electrode. A mathematical model is developed to analyze the relationship among material parameters, structural changes, and bending deformation. The curvature changes of the cantilever beam are captured by a charge-coupled device (CCD) camera during electrochemical cycling. Combining the model and bending curvatures, the modulus and swell strain are extracted and analyzed in detail. Here, the elastic modulus of the composite electrode softens and decreases from 9.59 GPa to 4.78 GPa, while the swell strain increases from 0.12% to 2.97% when arriving 6% normalized concentration of lithium. These results show that the composite material possesses excellent bending resistance and deformation ability. Also, the curvature changes under different thickness ratios are predicted successfully, the evolution of stress in the working electrode is simulated, and the loading experiment of the actuator is carried out. This work provides a new way to realize the controllability of the electrochemical actuators.

Sustainable Synthesis and Characterizationof Corncob‐Derived Graphene Oxide

AbstractRecently, though graphene oxide (GO) has shown promising applications in many fields, there have not been many studies focusing on exploiting the source of synthetic precursors of GO. Herein, GO was synthesized from the cellulose of corncob by corncob alkalization, bleaching cellulose, pyrolysis, and improved Hummer's method. It was found that pyrolysis plays an important role in the graphitization of cellulose precursors with the catalyst Fe(NO3)3 to form Gi‐Fe(NO3)3. The GO material synthesized from Gi‐Fe(NO3)3 was characterized by advanced analytical methods. The X‐ray diffraction pattern of Gi‐Fe(NO3)3 shows the formation of a diffraction peak at the crystal plane (002), which is characteristic of the graphite material. The synthesized GO underwent a series of changes in material structure and morphology, which are confirmed via transmission electron microscopy images showing a plate‐like structure with folds represented by the dark line. This study demonstrates a sustainable approach that directly utilizes abundant biomass resources for the synthesis of GO material.