Structural Integrity Of Material Research Articles

Glassy carbon electrodes modified with graphitic carbon nitride nanosheets and CoNiO2 bimetallic oxide nanoparticles as electrochemical sensor for Sunitinib detection in human fluid matrices and pharmaceutical samples.

Asophisticated electrochemical sensoris presented employing a glassy carbon electrode (GCE) modified with a novel composite of synthesized graphitic carbon nitride (g-C3N4) and CoNiO2 bimetallic oxide nanoparticles (g-C3N4/CoNiO2). The sensor's electrocatalytic capabilities for Sunitinib (SUNI) oxidation were demonstratedexceptional performance with a calculated detection limit (LOD) of 52.0nM. The successful synthesis and integrity of the composite were confirmed through meticulous characterization using various techniques. FT-IR analysis affirmed the successful synthesis of g-C3N4/CoNiO2 by providing insights into its molecular structure. XRD, FE-SEM, SEM-EDX, and BET analyses collectively validated the material's structural integrity, surface morphology, and electrocatalytic performance. Optimization of key analytical parameters, such as loading volume, concentration, electrolyte solution type, and pH, enhanced the electrocatalytic sensing capabilities of g-C3N4/CoNiO2. The synergistic interaction between g-C3N4 and CoNiO2 bimetallic oxide nanoparticles executed the sensor highly effective in the electrical oxidation of SUNI. Across a concentration range of 0.1-83.8µMSUNI, the anodic peak current exhibited a linear increasewith good precision. Application of the newly developed g-C3N4/CoNiO2 system to detect SUNI in a variety of samples, including urine, human serum, and capsule dosage forms, obtained satisfactory recoveries ranging from 97.1 to 103.0%. This methodology offers a novel approach to underscore the potential of the developed sensor for applications in biological and pharmaceutical monitoring.

PLLA scaffolds functionalized with ketoprofen via rotary jet spinning for biomedical applications

Biopolymer-based biomaterials, such as poly (l-lactic acid) (PLLA), have long been recognized as scaffolds for drug delivery applications due to their advantages, including biodegradability and biocompatibility. Ketoprofen (KET) is a non-steroidal anti-inflammatory drug known for its analgesic properties. Despite its potential, more research is needed on the effective production of scaffolds functionalized with KET for biomedical applications. This study, therefore, aimed to develop PLLA-based carriers to transport KET obtained using Rotary Jet Spinning (RJS) and evaluate the influence of KET at different concentrations. RJS allowed PLLA-KET scaffold production with high productivity and uniform fiber morphology. KET particles dispersed in the PLLA fibers were observed through scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Furthermore, the Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) confirmed the presence of KET in the PLLA and that the crystalline structure of PLLA remained unchanged with the incorporation of KET, ensuring the material's structural integrity. Likewise, the thermogravimetric analysis showed the presence of KET affected the thermal stability of PLLA. Cell viability and confocal microscopy with preosteoblast cells demonstrated that PLLA-KET fibers maintained cell viability over time, indicating their compatibility with cell cultures, and revealed cell adhesion and distribution in the fibers varied with KET concentration. These results have significant implications, highlighting the potential use of PLLA-KET carriers in practical biomedical applications, such as drug delivery systems, bone implant devices, and dental applications, thereby advancing the field of biomaterials.

Fluorine-ion-regulated yolk–shell carbon-silicon anode material for high performance lithium ion batteries

Silicon is considered as the next-generation anode material for lithium-ion batteries due to its high theoretical specific capacity and abundant crustal abundance. However, its poor electrical conductivity results in slow diffusion of lithium ions during battery operation. Simultaneously, the alloying process of silicon undergoes a 300 % volume change, leading to structural fractures in silicon during the cycling process.As a result, it loses contact with the current collector, continuously exposing active sites, and forming a sustained solid electrolyte interface (SEI) membrane. This paper presents the design of a fluorine-ion-regulated yolk–shell carbon-silicon anode material, highlighting the following advantages: (a) Alleviating volume changes through the design of a yolk–shell structure, thereby maintaining material structural integrity during cycling. (b) Carbon shell prevents silicon from coming into contact with the electrolyte, simultaneously improving silicon's electrical conductivity and increasing ion/electron conductivity. (c) Utilizing fluorine-ion interface modification to obtain an SEI membrane rich in fluorine components (such as LiF), thereby enhancing its long cycling performance. The F-Si@Void@C exhibits outstanding electrochemical performance, with a reversible capacity of 1166 mAh/g after 900 cycles at a current density of 0.5 A/g.

Lithium-Induced Oxygen Vacancies in MnO2@MXene for High-Performance Zinc-Air Batteries.

The traditional methods for creating oxygen vacancies in materials present several challenges and limitations, such as high preparation temperatures, limited oxygen vacancy generation, and morphological destruction, which hinder the application of transition metal oxides in the field of zinc-air batteries (ZABs). In order to address these limitations, we have introduced a pioneering lithium reduction strategy for generating oxygen vacancies in δ-MnO2@MXene composite materials. This strategy stands out for its simplicity of implementation, applicability at room temperature, and preservation of the material's structural integrity. This research demonstrates that aqueous Ov-MnO2@MXene-5, with introduced oxygen vacancies, exhibits an outstanding oxygen reduction reaction (ORR) activity with an ORR half-wave potential reaching 0.787 V. DFT calculations have demonstrated that the enhanced activity could be attributed to adjustments in the electronic structure and alterations in adsorption bond lengths. These adjustments result from the introduction of oxygen vacancies, which in turn promote electron transport and catalytic activity. In the context of zinc-air batteries, cells with Ov-MnO2@MXene-5 as the air cathode exhibit outstanding performance, featuring a significantly improved maximum power density (198.3 mW cm-2) and long-term cycling stability. Through the innovative strategy of introducing oxygen vacancies, this study has successfully enhanced the electrochemical catalytic performance of MnO2, overcoming the limitations associated with traditional methods for creating oxygen vacancies. Consequently, this research opens up new avenues and directions for nonprecious metal catalyst application in ZABs.

STRUCTURE PARAMETER OF INTERFACIAL INTERACTION IN Cf/C COMPOSITES AND ITS CHANGE DURING PORE FORMATION PROCESS

The C<sub>f</sub>/C composite oxidation of polyacrylonitrile-based carbon fibers with a combined carbon matrix at 600°C up to a weight loss of 80 wt% has been investigated. The changes in the open porosity, specific surface area, apparent and true densities of the composite, as well as the ultimate strength and elastic modulus during three-point transverse bending tests have been analyzed. An analytical model for obtaining qualitative and semi-quantitative estimates of the change in integral pore size during oxidation of heterophase materials has been developed. The change in pore size is estimated through the evolution of open porosity P and materials specific surface area S. The model has been validated in the C<sub>f</sub>/C composite oxidation study. The composite's mechanical properties dependences on the value of the integral pore size are obtained and analyzed. The structural parameter P/S characterizes the change in the interphase interaction during pores formation and development. It is established that the failure mechanism depends on the value of the parameter P/S and dynamically changes with the oxidation of C<sub>f</sub>/C composite. The use of P/S parameter as a criterion for estimation and control of composite materials structural integrity in open systems is proposed.

Low-temperature plasma-induced porous Sb2WO6 microspheres with rich oxygen vacancies to promote high-performance photocatalytic activity

The escalating issue of water pollution has sparked significant attention among researchers in the field of photocatalysis. Consequently, it holds immense significance to develop photocatalysts that exhibit high charge separation efficiency and stability for effectively degrading pollutants in water. In this study, OV-Sb2WO6-X photocatalyst was synthesized by incorporating oxygen vacancies into pristine Sb2WO6. The introduction of oxygen vacancies significantly enhanced the charge separation efficiency, resulting in a substantial improvement in the photocatalytic activity. The content of oxygen vacancies was controlled by plasma treatment time, processed for 10, 20 and 30 min, and electron paramagnetic resonance (EPR) test demonstrated the introduction of oxygen vacancies successfully. Furthermore, X-ray photoelectron spectroscopy (XPS) characterized the internal electron flow direction of the photocatalyst. OV-Sb2WO6-20 showed the degradation rate of Rhodamine B (RhB) that nine times of the Sb2WO6, while the Tetracyclines (TC) degradation rate showed 3.5 times that of Sb2WO6. Moreover, OV-Sb2WO6-20 exhibited superior stability in terms of recycling activity and material structural integrity. Additionally, free radical trapping experiments and electron spin-resonance spectroscopy characterization demonstrated that h+ played a crucial role as the reactive species during the degradation process. This research presents a viable approach for the modification of Sb2WO6-based materials, enabling effective treatment of dye wastewater and achieving successful purification.

Atomistic-Level Effects of Noncovalent Interactions and Crystalline Packing for Organic Material Structural Integrity upon Exposure to Gamma Radiation.

Developing an atomistic understanding of ionizing radiation induced changes to organic materials is necessary for intentional design of greener and more sustainable materials for radiation shielding and detection. Cocrystals are promising for these purposes, but a detailed understanding of how the specific intermolecular interactions within the lattice upon exposure to radiation affect the structural stability of the organic crystalline material is unknown. This study evaluates atomistic-level effects of γ radiation on both single- and multicomponent organic crystalline materials and how specific noncovalent interactions and packing within the crystalline lattice enhance structural stability. Dose studies were performed on all crystalline systems and evaluated via experimental and computational methods. Changes in crystallinity were evaluated by p-XRD and free radical formation was analyzed via EPR spectroscopy. Type of intermolecular interactions and packing within the crystal lattice was delineated and related to the specific free radical species formed and the structural integrity of each material. Periodic DFT and HOMO-LUMO surface mapping calculations provided atomistic-level identifications of the most probable sites for the radicals formed upon exposure to γ radiation and relate intermolecular interactions and molecular packing within the crystalline lattice to experimental results.

Cementing CO2 into C-S-H: A step toward concrete carbon neutrality.

Addressing the existing gap between currently available mitigation strategies for greenhouse gas emissions associated with ordinary Portland cement production and the 2050 carbon neutrality goal represents a significant challenge. In order to bridge this gap, one potential option is the direct gaseous sequestration and storage of anthropogenic CO2 in concrete through forced carbonate mineralization in both the cementing minerals and their aggregates. To better clarify the potential strategic benefits of these processes, here, we apply an integrated correlative time- and space-resolved Raman microscopy and indentation approach to investigate the underlying mechanisms and chemomechanics of cement carbonation over time scales ranging from the first few hours to several days using bicarbonate-substituted alite as a model system. In these reactions, the carbonation of transient disordered calcium hydroxide particles at the hydration site leads to the formation of a series of calcium carbonate polymorphs including disordered calcium carbonate, ikaite, vaterite, and calcite, which serve as nucleation sites for the formation of a calcium carbonate/calcium-silicate-hydrate (C-S-H) composite, and the subsequent acceleration of the curing process. The results from these studies reveal that in contrast to late-stage cement carbonation processes, these early stage (precure) out-of-equilibrium carbonation reactions do not compromise the material's structural integrity, while allowing significant quantities of CO2 (up to 15 w%) to be incorporated into the cementing matrix. The out-of-equilibrium carbonation of hydrating clinker thus provides an avenue for reducing the environmental footprint of cementitious materials via the uptake and long-term storage of anthropogenic CO2.

Anti-pulverization intermetallic Fe–Sn anchored on N-doped carbon anode boosted superior power and stable lithium storage

Tin (Sn) anode suffers from considerable volume deformation, generating vast dilatation-induced stresses leading to pulverization for lithium-ion batteries (LIBs). Herein, the Sn–Fe–C composite anode material with a jujube cake-like structure where Sn/FeSn2 metalcore anchored on an N-doped carbon matrix is constructed. During the lithiation process, the intermetallic Fe–Sn (FeSn2) generates Fe nanoparticles, which are uniformly distributed in the Sn matrix to relieve internal stress and create a conductive network, thus enhancing electron conduction and ion diffusion kinetics. In addition, the N-doped carbon matrix maintains the material structural integrity and improves overall conductivity. Consequently, the Sn–Fe–C anode delivers a high reversible 400 mAh g−1 over 1100 cycles at 5 A g−1 (capacity retention of up to 90.9%) and rate performance (237 mAh g−1 at 20 A g−1). Sn–Fe–C anode pairs with porous carbon (PC) cathode to assemble lithium-ion capacitors (Sn–Fe–C || PC LICs), which show a maximum energy density of 203.8 Wh kg−1, an excellent power density of 23925.3 W kg−1, and energy retention rate of 72.9% after 18,000 cycles at 1 A g−1. The Sn–Fe–C material as an anti-pulverization anode could be a potential application for high-performance LIBs and LICs in the future.

Solid-state additive manufacturing of tantalum using high-pressure cold gas-dynamic spray

Additive manufacturing (AM) of refractory metals, including tantalum (Ta), is highly valued due to the wide application of these materials in different industrial sectors where outstanding mechanical properties at elevated temperatures are required. Among metal AM processes, newly introduced cold gas-dynamic spray or, more commonly, cold spray (CS) offers a unique opportunity for solid-state consolidation of refractory metals. This research presents the CS process as a method for additive manufacturing of Ta. Following the successful manufacturing of free-standing Ta, an extensive mechanical characterization at the macro and nano levels has been carried out to evaluate the material's structural integrity. Anisotropy in the mechanical properties, which is one of the major concerns in the AM-produced materials, was extensively analyzed at both the macro and nano levels. The produced Ta's resistance against the pre-existing crack was studied by evaluating the far-field J-integral versus the crack extension (J-R curve). The influence of microstructural characteristics and process-induced defects such as pores and micro-cracks on the Ta's mechanical and fracture properties was studied to explain the performance-microstructure linkage. The macro and nanomechanical testing results indicated an elastic modulus and ultimate tensile strength in the range of vacuum-arc melted or electron-beam melted Ta ingots following cold-working. The microstructure analysis demonstrated a mixture of ultrafine grains and highly elongated coarse grains, explaining the CS-produced Ta high strength. Moreover, excellent isotropy in the mechanical properties was observed at both the macro and nano levels. This finding distinguishes the CS process from the laser-based AM process in which mechanical properties highly depend on the build direction. On the other hand, the CS-produced Ta exhibited brittle characteristics during uniaxial tensile loading and ductile behavior during the uniaxial compression test. Also, stable crack growth accompanied by crack branching was observed in the CS-produced Ta. The crack branching and formation of secondary cracks have been identified as the mechanisms retard crack extension. Overall, this research revealed that the CS process is a promising AM technique for producing tantalum-based components.

Operando structural investigations of thermoelectric materials

Operando characterization provides direct insight into material response under application conditions and it is essential to understand the stability limits of thermoelectric materials and their decomposition mechanisms. An operando setup capable of maintaining a thermal gradient while running DC current through a bar-shaped sample has been developed. Under operating conditions, X-ray scattering data can be measured along the sample to obtain spatially resolved structural knowledge in concert with measurement of electrical resistance and the Seebeck coefficient. Here thermoelectric β-Zn4Sb3, which is a mixed ionic–electronic conductor, is studied, and a significant temperature dependence of the Zn migration is directly observed. Measurements with the thermal gradient applied either along or opposite to the DC current establish that the ion migration is an electrochemical effect rather than a thermodiffusion. Consideration of only the applied critical voltage or current density is insufficient for deducing the stability limits and structural integrity of materials with temperature-dependent ion mobility. The present operando setup is not limited to studies of thermoelectric materials, and it also lends itself to studies of, for example, ion diffusion in solid-state electrolytes or structural transformations in solid-state reactions.

Rapid Processing of Whole Bamboo with Exposed, Aligned Nanofibrils toward a High-Performance Structural Material.

Lightweight structural materials are critical in construction and automobile applications. In past centuries, there has been great success in developing strong structural materials, such as steels, concrete, and petroleum-based composites, most of which, however, are either too heavy, high cost, or nonrenewable. Biosourced composites are attractive alternatives to conventional structural materials, especially when high mechanical strength is presented. Here we demonstrate a strong, lightweight bio-based structural material derived from bamboo via a two-step manufacturing process involving partial delignification followed by microwave heating. Partial delignification is a critical step prior to microwave heating as it makes the cell walls of bamboo softer and exposes more cellulose nanofibrils, which enables superior densification of the bamboo structure via heat-driven shrinkage. Additionally, microwave heating, as a fast and uniform heating method, can drive water out of the bamboo structure, yet without destroying the material's structural integrity, even after undergoing a large volume reduction of 28.9%. The resulting microwave-heated delignified bamboo structure demonstrates outstanding mechanical properties with a nearly 2-times improved tensile strength, 3.2-times enhanced toughness, and 2-times increased bending strength compared to natural bamboo. Additionally, the specific tensile strength of the modified bamboo structure reaches 560 MPa cm3 g-1, impressive given that its density is low (1.0 g cm-3), outperforming common structural materials, such as steels, metal alloys, and petroleum-based composites. These excellent mechanical properties combined with the resource abundance, renewable and sustainable features of bamboo, as well as the rapid, scalable manufacturing process, make this strong microwave-processed bamboo structure attractive for lightweight, energy-efficient engineering applications.

Autonomous Self-Healing to Combat Insulation Failure

It is challenging to endow artificial synthetic materials with autonomous self-healing capacity. In this issue of Matter, He and coworkers used in situ generated electroluminescence to initiate photopolymerization to autonomously heal electrical trees in dielectric polymers without the introduction of external stimuli.

Light-Stabilized Dynamic Materials.

The light-responsive adaptation of polymer materials typically requires different wavelengths or additional heat to induce reversible covalent bond formation and dissociation. Here, we bypass the use of invasive triggers by introducing light-stabilized dynamic materials that can undergo a repeatable change in topology from a covalently cross-linked material into a liquid polymer formulation by switching one visible light source on-and-off without the need for any additional triggers. Specifically, we exploit the photo-Diels-Alder reaction of triazolinediones with naphthalenes as a dynamic covalent cross-linking platform that enables green light-induced network formation, while the cross-linked material collapses through spontaneous cycloreversion upon standing in the dark at ambient temperature. Importantly, the covalent cross-links remain stabilized for as long as visible light is present, thereby retaining the material's structural integrity. This enables their potential use in an array of light-directed applications whereby network properties such as stiffness can be tuned by the mildest trigger of all: darkness.

Aircraft Corrosion – Review of Corrosion Processes and its Effects in Selected Cases

Abstract From the safety point of view, one of the most important issues regarding aircraft operations is ensuring the durability of the structural components. Corrosion processes can have a significant effect on the integrity of structural materials and are usually associated with aircraft aging. Due to the variety of materials used, environments and loads impacting the planes, a wide range of different types of corrosion may occur in aircraft structures. The main aim of this study is to present some theoretical knowledge related to corrosion processes as well as problems of aircraft structures associated with corrosion occurrence. Firstly, the paper presents a brief overview of what corrosion is and what different types of corrosion are. Secondly, some selected aircraft failures caused by corrosion are shortly presented and discussed.

Simulation of internal stress waves generated by laser-induced damage in multilayer dielectric gratings.

Multilayer dielectric (MLD) gratings used in ultrahigh-intensity laser systems often exhibit a laser-induced damage performance below that of their constituent materials. Reduced performance may arise from fabrication- and/or design-related issues. Finite element models were developed to simulate stress waves in MLD grating structures generated by laser-induced damage events. These models specifically investigate the influence of geometric and material parameters on how stress waves can lead to degradation of material structural integrity that can have adverse effects on its optical performance under subsequent laser irradiation: closer impedance matching of the layer materials reduces maximum interface stresses by ~20% to 30%; increasing sole thickness from 50 nm to 500 nm reduces maximum interface stresses by ~50%.

STRUCTURAL INTEGRITY OF MATERIALS AND STRUCTURES

"Editorial. Structural integrity of materials and structures" Engineering Structures and Technologies, 9(4), pp. 157

Effect of process parameters on the microstructure, hardness and wear resistance properties of Zn-Sn-Ti coatings on AISI 1015 steel: laser alloying technique

The deterioration of materials during industrial application poses a serious threat to the materials structural integrity. A material's susceptibility to wear and surface damage can be reduced by alteration of its surface chemistry, morphology and crystal structure which plays an important role in optimising a material's performance for a given application. The aim of the research was to investigate the enhancement in the microstructure and wear property of Zn-Sn-Ti ternary coatings on AISI 1015 steel by laser alloying technique using Ytterbium laser system (YLS). A laser power of 750-900 W, scanning speeds of 0.6 and 0.8 m/min, and alloy compositions of 25Zn-25Sn-50Ti and 20Zn-20Sn-60Ti were used in this study. At optimum composition of 20Zn-20Sn-60Ti and speed of 0.8 m/min, there was enhancement of 24% in wear resistance performance which was attributed to metastable intermetallic phases. The coatings were free of cracks with homogeneous and refined microstructures and good adhesion to the substrate. The response surface model (RSM) used authenticates reasonably with the experimental results.

Effect of Process Parameters on the Microstructure, Hardness and Wear Resistance Properties of Zn-Sn-Ti Coatings on AISI 1015 Steel: Laser Alloying Technique

The deterioration of materials during industrial application poses a serious threat to the materials structural integrity. A material's susceptibility to wear and surface damage can be reduced by alteration of its surface chemistry, morphology and crystal structure which plays an important role in optimising a material's performance for a given application. The aim of the research was to investigate the enhancement in the microstructure and wear property of Zn-Sn-Ti ternary coatings on AISI 1015 steel by laser alloying technique using Ytterbium laser system (YLS). A laser power of 750-900 W, scanning speeds of 0.6 and 0.8 m/min, and alloy compositions of 25Zn-25Sn-50Ti and 20Zn-20Sn-60Ti were used in this study. At optimum composition of 20Zn-20Sn-60Ti and speed of 0.8 m/min, there was enhancement of 24% in wear resistance performance which was attributed to metastable intermetallic phases. The coatings were free of cracks with homogeneous and refined microstructures and good adhesion to the substrate. The response surface model (RSM) used authenticates reasonably with the experimental results.

Acoustoelastic Coefficients in Thick Steel Plates under Normal and Shear Stresses

Ultrasonic monitoring of the integrity of structural materials utilizes the acoustoelasticity of materials (stress-dependence of ultrasonic wave velocity) obtained from the higher order strain terms in the constitutive equations. This method has been applied to measure residual and applied stresses in thin metals under principal stresses without shear. Here, acoustoelastic coefficients are determined in thick steel plates in normal, orthogonal, and angled directions by means of an array of ultrasonic sensors. A three-dimensional material model is developed which includes Murnaghan hyper-elasticity and can determine the effects of plate thickness and excitation frequency on the acoustoelastic coefficients. This model is experimentally validated by tensile loading of a thick steel plate by measuring the ultrasonic signals in three directions. Numerical and experimental results agree within the measurement uncertainties of each method. The 1.0 MHz ultrasonic frequency has the highest resolution for measuring normal and shear stresses in structural plates typically used in highway bridges.