Material Characteristics Research Articles

Hydrogen Embrittlement of Advanced High-strength Steel S960MC Used in Transport and Vehicle Industry and the Influence of Potassium Thiocyanate during Hydrogenation

Advanced high-strength steels (AHSS) are currently facing a serious challenge from hydrogen embrittlement, which significantly affects their mechanical properties. Problems arise when hydrogen diffuses into the material and accumulates at grain boundaries, inclusions, or microcracks, degrading the material's characteristics. The main objective of the study is to investigate the effects of adding potassium thiocyanate (KSCN) to the sulfuric acid base solution during electrolytic hydrogenation using microalloyed martensitic AHSS grade S960MC. An increase in hydrogen diffusion into the examined material across its full surface is produced by adding thiocyanate ions to the electrolyte. This is the rationale behind the decision to add KSCN to the sulfuric acid base solution. The addition of KSCN to the base environment induced a considerable reduction in fracture strain, and the degradation was attributed to hydrogen buildup at grain boundaries, impurities and microcracks. These steels have an extensive list of applications in the automotive industry and are frequently used in the form of sheets for welding. Therefore, it is important to understand how their mechanical characteristics and behaviour vary in various circumstances, including hydrogen-rich environments.

Dimensionality and strain-dependent properties of Orthorhombic (100) NaTaO3 thin films: A comprehensive DFT investigation

The modulation of perovskite oxide thin films’ properties, through both intrinsic and extrinsic methods, has been extensively studied to enhance their photocatalytic performance. We employed ab initio density functional theory calculations to investigate the layer-dependent structural and electronic properties of orthorhombic NaTaO3 thin films. Our findings reveal that slabs comprising five, four, and three layers retain the non-magnetic and semiconducting characteristics of the bulk material, with their properties progressively converging towards those of an infinite-surface slab as the number of layers increases. Biaxial in-plane strain induces a linear change in the structure of surface TaO4 tetrahedra, thereby altering the film’s band gap. Notably, the two-layer slab exhibits a transitional behavior between the bulk-like nature of thicker films and the unique features of a NaTaO3 monolayer, showing heightened sensitivity to strain. Under compression, this bilayered system acquires bulk-like properties, whereas its strain-free state is magnetic and metallic akin to the monolayer. Similar transitions are observed in the latter, though under higher compression values. We provide an in-depth discussion of the structural and electronic mechanisms underlying these transitions. Additionally, the relative band-edge alignment with water-splitting photocatalytic potentials underscores the complex interplay between strain and dimensionality. This work offers valuable insights towards the design of more efficient photocatalysts, highlighting the potential of engineered NaTaO3 thin-film structures for advancing photocatalytic applications.

Cotton wool-like ion-doped bioactive glass nanofibers: investigation of Zn and Cu combined effect

Electrospinning is a versatile and straightforward technique to produce nanofibrous mats with different morphologies. In addition, by optimizing the solution, processing, and environmental parameters, three-dimensional (3D) nanofibrous scaffolds can also be created using this method. In this work, the preparation and characterization of bioactive glass (BG) scaffolds based on the SiO2-CaO sol-gel system, a biomaterial with a highly reactive surface, is reported. The electrospinning technique was combined with sol-gel methods to obtain nanofibrous 3D cotton wool-like scaffolds. The addition of zinc and copper ions to the silica-calcia system was examined, and the influence of these ions on the material properties and characteristics was investigated by various characterization techniques, from morphological and chemical properties to antibacterial and wound closure capability, cell viability and ion release. Our findings show that the cotton wool-like ion-doped nanofibers are promising for wound healing applications.

Organic Ferroelectrics for Regulation of Electronic and Ionic Transport Toward Neuromorphic Applications

AbstractOrganic ferroelectrics (OFEs) have been of significant research interest not only for nonvolatile memory applications but also for their unique material characteristics such as mechanical softness, biocompatibility, facile processibility, and chemically tailorable functionalities that inorganic counterparts are hard to achieve. Despite these promising merits, the utilization of OFEs has mainly focused on simply demonstrating flexible nonvolatile memories wherein modulation of electronic conductance is of interest. Recent studies indicate that the applicability of OFEs can be further extensive, particularly when combined with electronic, ionic, and mixed electronic‐ionic conducting media. Herein, we discuss that OFEs can be employed for the regulation of electronic as well as ionic charges, and lead to unique device behaviors. First, we comprehensively introduce organic ferroelectric materials classified with their structures and compositions. Next, we discuss recent studies where organic ferroelectricity has been incorporated with electronic, ionic, or mixed transport system to resolve issues in devices and endow multifunctionality, which are promising for neuromorphic computing and sensory memory systems. Finally, insight into the research direction of OFEs is provided, and what hurdles shall be overcome for real‐world applications.

A 3D self-floating evaporator loaded with phase change energy storage materials for all-weather desalination

Today, humanity is confronted with two interrelated crises: water and energy scarcity. The utilization of solar energy to evaporate seawater enables the acquisition of freshwater resources while minimizing energy consumption. However, the solar energy hitting the ground is associated with different weather patterns and the alternation of day and night. This work is based on chitosan (CS) aerogel, loaded with phase change material octadecane (ODE) and coated with epoxy resin glue and electrospinning fiber photothermal layer for continuous evaporator operation. Using the characteristics of phase change materials, the ODE undergoes a change from solidification to liquefaction, during which it absorbs and stores energy at elevated temperatures. Conversely, when the temperature decreases, the ODE reverts to solidification and releases stored energy. This enables the evaporator to be utilized in a broader range of scenarios, thereby enhancing the continuity of evaporation. The temperature of the evaporator remained higher than the initial temperature 2 h after the light source was switched off, achieving a light absorption of 94 % and an evaporation rate of 1.74 kg m−2 h−1. Furthermore, it exhibits purification capabilities for different kinds of solutions. The interfacial evaporator is capable of facilitating all-weather evaporation, and it has the potential to become a pivotal instrument in the domain of seawater desalination, with a vast array of applications.

Zirconia Ageing is related to Total Hip Arthroplasty Aseptic Loosening. A Study of 45 Retrieved Zirconia Heads

BackgroundY-TZP zirconia heads were recalled by the Food and Drug Administration (FDA) in 2001 and zirconia alone was no longer used in orthopedics. Tunnel furnace sintering was suspected of producing defects responsible for early material failure. As Zirconia Toughened Alumina (ZTA) matrices are widely used as bearing material and contain zirconia grains, there remains a need to better understand the in vivo ageing process of zirconia and its clinical implications when the material is produced by batch furnace sintering, the validated sintering process. Questions/objectivesIs there an association between the ageing of batch furnace produced zirconia and THA revision? Methods45 retrieved femoral heads, batch furnace sintered only, were analyzed. Roughness was measured by 3D profilometry, phase transfer by µRaman spectroscopy.Clinical data were compared with material characteristics. ResultsIrrespective of the cause of revision, all heads showed a crystallographic phase transition from tetragonal to monoclinic over 19.5%. A correlation was found between the phase change, roughness increase and aseptic loosening, with a threshold set at 24.5% of monoclinic phase. ConclusionsThe ageing process of zirconia may lead to aseptic loosening, which, in the absence of contrary evidence, prohibits its use as the sole component of orthopedic materials. ZTA matrices should be clinically monitored, especially in young patients, and better in vitro modelling needs to be performed. Level of evidenceIV; Case series.

The Solid‐State Battery Applicational Technology: Material Characteristics and Charge–Discharge Mechanisms of Iron Chloride Electrodes

ABSTRACTThis study delves into the unique characteristics of an iron chloride cathode with a solid‐state electrolyte (SSE) and the construction of a button cell battery (BT cell) for its evaluation. The iron ions in this system can provide either divalent or trivalent ions, which possess a higher electrical capacity (~200 mAh/g) and competitive advantages. The solid‐state electrolyte materials, iron compounds (chloride, oxide), exhibit high activation in electrochemistry. After the cycle test, the ferric chloride electrolyte transforms into another iron hydroxide compound due to its high activation. The study examines iron, ferric oxide (Fe2O3), and ferrous chloride (FeCl2) as cathode materials and evaluates their impact on the battery. Cyclic voltammetry compares the potential and current values of the redox reactions among the three. Finally, transmission electron microscopy (TEM) explores the ferric chloride layer and iron hydroxide in ferrous chloride. The study focuses on the high electrochemical activity of the iron chloride layer and explores the crystal structure and composition for electrochemical analysis. The findings of this study are crucial for understanding the potential of iron‐ion batteries and the role of iron compounds in improving battery performance.

Flow field characteristics and drag reduction performance of high–low velocity stripes on the biomimetic imbricated fish scale surfaces

AbstractImproving energy efficiency and cost reduction is a perennial challenge in engineering. Natural biological systems have evolved unique functional surfaces or special physiological functions over centuries to adapt to their complex environments. Among these biological wonders, fish, one of the oldest vertebrate groups, has garnered significant attention due to its exceptional fluid dynamics capabilities. Researchers are actively exploring the potential of fish skin's distinctive structural and material characteristics in reducing resistance. In this study, models of biomimetic imbricated fish scale are established, and the evolution characteristics of the flow field and drag reduction performance on these bionic surfaces are investigated. The results showed a close relationship between the high–low velocity stripes generated and the fluid motion by the imbricated fish scale surface. The stripes' prominence increases with the spacing of the adjacent scales and tilt angle of the fish scale, and the velocity amplitude of the stripes decreases as the exposed length of the imbricated fish scale surface increases. Moreover, the biomimetic imbricated fish scale surface can decrease the velocity gradient and thereby reduce the wall shear stress. The insights gained from the fish skin‐inspired imbricated fish surface provide valuable perspectives for an in‐depth analysis of fish hydrodynamics and offer fresh inspiration for drag reduction and antifouling strategies in engineering applications.

Unveiling the water sorption kinetics, thermodynamics, and air dehumidification performance of sustainably synthesized metal–organic frameworks

This study focuses on the feasibility of sustainably synthesized MIL-100(Fe) as an alternative to conventional desiccants, such as silica gel and zeolites, which have low adsorption capacity and poor thermal characteristics for air dehumidification. MIL-100(Fe), a metal–organic framework, shows promise due to its excellent adsorption and customizable thermal properties. However, its synthesis typically involves toxic materials and high temperature/pressure conditions, which restrict its bulk production for large-scale applications. This study aims to explore sustainable synthesis methods for MIL-100(Fe) using non-toxic materials and milder reaction conditions and investigate its material characteristics and dehumidification performance. Experimental analyses are carried out to measure adsorption isotherms, kinetics, sorption heat, activation energy, and cyclic stability, and numerical simulations are conducted in COMSOL Multiphysics platform to estimate dehumidification performance. The test results demonstrate that MIL-100(Fe) has a higher water adsorption capacity compared to silica gel, with a unique stepwise adsorption into its two types of mesoporous cages. Increased temperatures cause the adsorption and desorption isotherms to shift towards higher relative humidity levels. The heat of water adsorption and desorption ranges between 2630–2906 kJ/kg and 2763–2848 kJ/kg, respectively. MIL-100(Fe) demonstrates high stability and no significant loss in water uptake capacity. The simulated performance indicate that MIL–100(Fe) has superior reaction rates and is 82 % more effective than the silica gel rotary wheel dehumidifiers.

Research on Iron Gallium Dipole Logging Transducers

Abstract Orthogonal dipole acoustic logging is an indispensable means to study the mechanical properties of formation rocks, estimate formation porosity and permeability, and carry out out-of-hole remote detection, and the broadband high-power dipole acoustic logging transducer is one of its core components, which is an urgent and unsolved international problem in actual logging. Therefore, it is of great application background and important academic significance to study the new dipole acoustic logging transducer and overcome the related scientific problems. On the basis of full investigation and study of the characteristics of iron gallium materials, this project first designed the iron gallium bending beam oscillator to verify the feasibility of iron gallium bending vibration, and then designed the iron gallium dipole acoustic logging transducer, optimized the driving magnetic circuit, simulated the driving performance of the transducer, and preliminarily verified the feasibility of the design.

Development of electrode and electrolyte materials for solid-state batteries based on Li1.3Al0.3Ti1.7(PO4)3

The dependence of the electrochemical characteristics of a layered cathode material containing LiNi0.5Mn0.3Co0.2O2 on the method for applying a protective layer of nanoparticles of the lithium-conducting material Li1.3Al0.3Ti1.7(PO4)3 with a NASICON structure to its surface has been studied. The surface modification has been found to improve the capacity retention in prolonged charge/discharge cycling (up to 15%) and to allow fast charge/discharge processes. The possibility of using a composite electrolyte consisting of a porous ceramic matrix of aluminum-substituted lithium titanium phosphate Li1.3Al0.3Ti1.7(PO4)3 with a transition layer of liquid electrolyte LP-71 has been shown. The use of a thick composite solid electrolyte results in a slight reduction (∼5–7 mAh g−1) in initial capacity compared to laboratory cells with the widely used Celgard 2400 separator impregnated with liquid electrolyte. Laboratory cells assembled with a composite electrolyte showed higher stability during charge/discharge cycling: after 80 deep charge/discharge cycles, the capacity reduction was ∼12% for cells with a composite electrolyte, while for the reference cell it was ∼23%.

Strength and deformation characteristics of construction materials of civil engineering historical sites since the end of the Edo shogunate

Strength and deformation characteristics of construction materials of civil engineering historical sites since the end of the Edo shogunate

Effects of furnace temperature of stress-relief annealing on residual stress and hardness characteristics of heterogeneous materials fabricated from a DED process

Effects of furnace temperature of stress-relief annealing on residual stress and hardness characteristics of heterogeneous materials fabricated from a DED process

Analysis of noise and its characteristics in avalanche photodiode

Avalanche photodiodes (APDs) produce noise during operation, which affects the device performance. However, the previous research on its noise is mainly theoretical analysis and is only reflected as optical noise. Therefore, according to the characteristics of APD material and the mechanism of noise generation, the main noise of the device is analyzed in this paper. First, the test method of noise in APDs is established, including testing of dark noise, optical noise, and multiplication noise in high frequency bands. The main noises in APDs are 1/f noise, thermal noise, shot noise, generation recombination noise, and multiplication shot noise, and shot noise is suppressed by Fermi–Dirac distribution and Coulomb action. Second, the reliability of APDs is evaluated by measuring and analyzing the noise parameters of the device through thermal aging experiments. It is concluded that the defects introduced by thermal aging can be reflected by the change in noise, which is consistent with the results in the literature. This method can comprehensively obtain the noise in APDs, which is helpful to improve the working efficiency, life, and reliability of the device.

A novel large-scale direct shear apparatus considering size effects on strength of frozen coarse-grained soils

As engineering activities in cold regions expand and the application of artificial ground freezing technology in constructions grows, understanding the strength of frozen coarse-grained soils has become imminently crucial. While existing research and testing methods have provided valuable opinions into the behavior of coarse-grained materials in frozen states, there is a recognized need to enhance and expand these methods to gain a more comprehensive understanding of how size effects influence the strength of these materials. To further investigate this issue, a novel large-scale direct shear apparatus was employed to determine the shear strength of frozen coarse-grained soil materials. The apparatus features a unique design capable of accommodating square specimens with five different section lengths: 100 mm, 150 mm, 200 mm, 250 mm, and 300 mm. Depending on the maximum load requirements and budget constraints of the experiment, the equipment can provide a maximum normal stress of 5.5–50 MPa and a maximum shear stress of 3.5–30 MPa for different sample sizes, along with precise temperature control down to −30 °C. The efficacy of the device is validated through experiments conducted on frozen coarse-grained soil samples with specific particle size distributions. This study presents the technological details involved in the development of the apparatus and offers preliminary insights into the strength characteristics of frozen coarse-grained soils, highlighting the influence of size effects. The innovative features of the apparatus help the geotechnical community to comprehensively understand the strength characteristics of this complex material, thereby improving the reliability of engineering practices that involve it.

Experimental investigations of the wear behaviour of railway brake block raw materials

Abstract Passenger and freight transport by rail is gaining ground not only in Europe, but in many countries around the world. At the same time, due to the increased traffic, the need to investigate the effects of rail transport on the environment and to reduce the harmful effects is also increasing. One of the recurring problems is the reduction of the noise that occurs during the braking of railway cars, as well as the mitigation of particles released during braking and, as a result, the reduction of their health-damaging effects. In more and more European countries, the so-called Noise Differentiated Track Access Charges (NDTAC) is being introduced, where the cost depends on the amount of noise emitted during braking. For this reason, the examination of the friction conditions of the materials used in railway brakes and the finding of materials with the most favourable properties is a priority area of research. In this paper, the initial investigations of a recently started research project on the subject are presented, the aim of which is to develop and test new layered composite materials that may be used in the future to produce railway brake blocks. The paper presents the main objectives of the project, the principles, and tools of the friction tests to be applied, as well as the test measurements carried out, during which the friction characteristics of copper alloy and aluminium control materials along with the currently used cast iron and composite brake blocks were examined.

Sound absorbing characteristics of granular materials with elastic modulus varying along gravitational direction for vertical and horizontal sound propagations

Sound absorbing characteristics of granular materials with elastic modulus varying along gravitational direction for vertical and horizontal sound propagations

Effect of nanomaterials on the melting/freezing characteristics of phase-change material

A novel variant of composite phase-change material (PCM) was developed by incorporating 0.5 wt% aluminum oxide (Al2O3), silicon dioxide (SiO2), copper (II) oxide (CuO) and silver (Ag) nanomaterials into myristic acid. In this formulation, myristic acid served as the foundational material, while aluminum oxide, silicon dioxide, copper (II) oxide and silver were employed as supporting components. The morphology and crystalline structure of the nanomaterials were studied using field-emission scanning electron microscopy and X-ray diffraction analysis, respectively. The composite PCMs were fabricated using a two-step process. The phase-change properties of the composite PCMs were assessed using differential scanning calorimetry. The nanomaterials (0.5 wt% aluminum oxide, silicon dioxide, copper (II) oxide and silver) were suspended in myristic acid separately to investigate the heat-transfer performance of the composite PCMs during phase-change processes (melting and freezing). The results clearly indicated that the duration of the melting and freezing processes of the composite PCMs decreased compared with that of the pure PCM. Thus, the newly prepared composite PCMs are potential candidates for harvesting solar energy for low-temperature heating applications.

In vitro evaluation of the effect of two pediatric syrups on the microhardness and surface roughness of restoration materials.

The prolonged use of pediatric syrups without adequate control of oral hygiene can cause effects on the physical characteristics of the restoration materials, which in turn can cause deterioration of the material and subsequent carious recurrence. Aim: To evaluate the effect of two long-term use syrups in children on the microhardness and surface roughness of three restorative materials. Three study groups were formed, consisting of a conventional self-curing ionomer cement, a light-curing ionomer cement, and a light-curing composite resin. Each group had 40 specimens made with the respective restorative material; in addition, these were distributed in 2 subgroups with 20 specimens each, which were immersed in Paracetamol and Ferrous Sulfate in syrup following a protocol that consisted of 2 minutes each day for 28 days. Over time (0, 7, 14, 21, and 28 days), when evaluating microhardness, the composite resin subgroup exposed to ferrous sulfate (p = 0.027) and the Ketac Molar ionomeric cement subgroup (p = 0.002) exposed to Paracetamol showed statistically significant differences; while, when evaluating surface roughness, the composite resin subgroups (p = 0.032) and Ketac Molar ionomeric cement (p = 0.01) exposed to ferrous sulfate showed a statistically significant difference. The more days of exposure to ferrous sulphate syrup, the less the microhardness of the composite resin decreases; something similar occurs with the microhardness of Ketac Molar ionomeric cement when exposed to Paracetamol syrup. Meanwhile, the surface roughness of the composite resin and Ketac Molar ionomeric cement increases considerably when exposed to ferrous sulphate. Key words:Ionomeric cement, Microhardness, Composite resins, Surface roughness.

Simplified evaluation method of shear strength characteristics of embankment materials applied to aseismic diagnosis of existing embankments

Simplified evaluation method of shear strength characteristics of embankment materials applied to aseismic diagnosis of existing embankments