Composition Of Layer Research Articles

Microstructure and friction properties of NiTi2-based composite layer prepared by ultrasonic assisted underwater wet laser deposition

An in situ TiC-enhanced NiTi2-based composite deposition layer was prepared by ultrasonic assisted underwater wet laser deposition. The evolution of the microstructure and interface state, and the friction properties in the air and brine solution environments of the deposition layer were analyzed and researched. The results demonstrated that the thermal and steady-state cavitation from ultrasound effects increase the total energy of the melt pool and promote mixing. The dilution rate of the ultrasonic assisted underwater laser deposition layer increases to 86.72 % compared with that of the underwater laser deposition layer (78.75 %). Ultrasonic reduced underwater laser deposition defects such as lack of fusion and weld slag, and enhanced the wettability between the deposition layer and substrate. The contact angle of the UWNT layer (24.40°, in average) is smaller than the WNT layer (29.80°, in average). Ultrasonic shortened the contact time between the deposition layer surface and the solution, which reduced the reaction of the Ni element with the brine solution. It also transformed the deposition layer from hypereutectoid microstructure to hypoeutectic microstructure and from planar interface to cellular interface. With the effect of the ultrasonic field, the elements in the deposition layer become more uniformly distributed and the secondary phases undergo spheroidization. In the ultrasonic assisted deposition layer, stress-induced FCC-Ti was discovered. Ultrasonic field also reduced the dispersion of the microhardness and increased the average microhardness to 863.3 ± 45.1 HV0.3. Tribology properties show that ultrasonic field effectively improved the wear resistance and friction stability of the ultrasonic assisted deposition layer. The COF of the ultrasonic assisted deposition layer was less affected by the environment, with values of 0.25 and 0.24 observed in air and brine solution, respectively. Overall, the research results in this paper can provide a new insight to improve the surface properties of NiTi2-based alloy underwater laser deposition.

Interface characteristics and fracture mechanism of laser-arc hybrid welded Al-Ti dissimilar butt-joint through beam oscillation

Two laser oscillating patterns including circle and inscribed double-circle were adopted for the laser-arc hybrid welding of Al-Ti dissimilar butt-joint, and compared with the none-oscillating hybrid welding. The results showed that a two-layer intermetallic compounds (IMCs) including Al3Ti and Al2Ti was formed at the Al-Ti interface without laser oscillation, and the thickness (τ) of IMCs layer reached up to 5.56 μm. The IMCs layer was transferred to a single-layer Al2Ti with decreased the τ to 1.18 μm by the optimized inscribed double-circle oscillating hybrid welding. The optimized laser oscillation benefited to form local turbulences inside the molten pool, which optimized the composition of interface IMCs layer and effectively reduced its thickness. Due to the combined improvements, the ultimate tensile strength of Al-Ti dissimilar butt-joint was increased by 18% from 182.6 to 215 MPa. The corresponding tensile fracture of welded joint changed from the two-layer IMCs layer to the base metal. Because no orientation relationship between them along the Al3Ti/ Al2Ti was formed, the tensile crack preferentially propagated between the Al3Ti and Al2Ti IMCs at the interface, resulting in the poor tensile properties.

Application and Evaluation of Cone Penetration Testing for Determining Internal Friction Angle in Composite Subgrade Cushion Layer

Application and Evaluation of Cone Penetration Testing for Determining Internal Friction Angle in Composite Subgrade Cushion Layer

Detection of Layer Charge Density in Layered Double Hydroxides and Studies on Host‐Guest Interactions

AbstractThe layer charge density of layered double hydroxides (LDHs) significantly affects interlayer spacing, the arrangement of interlayer anions and water molecules, thermal stability, as well as adsorption performance. However, traditional methods for evaluating the layer charge density of LDHs are complex, prone to large errors, and impacted by numerous factors, rendering these methods unable to facilitate direct comparisons of layer charge density across different LDH compositions. Consequently, this study proposes a novel approach based on the host‐guest supramolecular interactions in LDHs to investigate the layer charge density by analyzing changes in the position of the infrared absorption peaks of interlayer guest species. The shifts in infrared absorption peak positions are employed to assess the layer charge density of MgAl‐LDHs with varying molar ratios (M2+/M3+=2, 2.5, 3, 3.5, 4). The validity of using infrared peak position shifts is corroborated through a combination of techniques, including Raman spectroscopy, TG‐DTG, XRD, Zeta potential, and adsorption analyses. Furthermore, the layer charge density of NiAl, CoAl, MgFe, and NiFe‐LDHs are evaluated, confirming the universality of the infrared method. By ranking layer charge density of LDHs with different compositions and ratios, this study resolves the challenge of comparing LDHs with diverse layer compositions.

Fabrication and High Dielectric Properties of Sandwich-Structured Ba0.6Sr0.4TiO3/Polyvinylidene Fluoride Layered Composites with Multiscale Parallel Interfaces.

Ba0.6Sr0.4TiO3/polyvinylidene fluoride (BST/PVDF) dielectric functional composites have been widely used in flexible wearable devices, capacitors, and energy storage devices. In addition to the ceramic phase type, polymer matrix type, composition, and interfacial connectivity of BST/PVDF composite materials, their morphology also significantly influences their electrical characteristics. Therefore, herein, sandwich-structured BST/PVDF layered composites were designed and prepared via tape-casting processing using different types of BST fillers [i.e., formless zero-dimensional (0D)-BST, rod-like one-dimensional (1D)-BST, and plate-like two-dimensional (2D)-BST]. The microstructures and electrical characteristics of sandwich-structured BST/PVDF composites were studied in relation to the BST morphology. The effects of the internal mechanisms of different interfacial models on the breakdown strength of BST/PVDF composites were discussed. According to our findings, unlike the 0D-BST and 1D-BST powders, 2D-BST powders form multiscale parallel interfaces in sandwich-structured composites due to their unique lamella-like morphology, which enhances the breakdown strength of sandwich-structured composites. Sandwich-structured BST/PVDF composites containing 2D-BST powders exhibit good electrical characteristics with an energy storage density of 19.71 J/cm3, an energy storage efficiency of 85.3%, a dielectric constant of 30.4 (1 kHz), a dielectric loss of 0.036 (1 kHz), and a dielectric tunability of 93.2%. This study provides a method for preparing functional composites with high dielectric tunability and high energy storage characteristics.

Metal Replacement in Aeronautics Applications Using Two‐Dimensional Multifunctional Composites

Carbon‐based composites have replaced metals in many structural components of modern airplanes; however, functional applications still require metal conductors and devices. Here, the production and integration in small‐scale airplane parts of electric devices based on metal‐free layered composites of graphene, boron nitride, and polymers are described. Thanks to their two‐dimensional structure, these materials feature excellent tunable thermoelectrical properties and high flexibility. We describe the production and performance of heaters and ice sensors installed on scaled NACA‐0012 airfoils to avoid ice formation, to remove ice or to detect the ice on the outer skin of the airfoil. We demonstrate that we can tune the electrical conductivity of the composite heating element from 105 to 103 S m−1 that is preserved even after 1000 bending cycles. The heaters successfully achieve anti‐icing and deicing in representative icing conditions and can sustain high‐power densities as required for electrothermal ice‐protection systems in aviation. The composite material can be readapted into a sensor able to detect ice formation in real time in an icing wind tunnel. Moreover, the possibility to use the heaters developed as heating molds to cure composite materials by out‐of‐oven curing, with a significant energy saving potential, is demonstrated.

Constitutive modeling of thermo-chemical decomposition and thermo-mechanical deformation, coupled with transient heat conduction, in ablative matrix composite

Several thermal protection systems employ sacrificial composite layer that undergoes thermo-chemical decomposition in high-temperature environment. This results in the pyrolysis gas formation (endothermic reaction) that gets trapped inside the voids generated in the ablative matrix phase. These trapped gases apply pore pressure on the structure, along with the mechanical loading, thus significantly influencing the structure failure. A novel thermo-chemical (TC) decomposition and thermo-mechanical (TM) deformation-based coupled multi-physics formulation, applicable to ablative composite systems, is thus presented. A novel shrinkage expression, due to ablative matrix decomposition, is derived. The TC + TM coupled formulation is converted to stress update process, and its results are validated against the available experimental data. The proposed formulation is also converted to boundary value problem employing non-linear finite element framework (NL-FEM). The Jacobian matrices, for one- and two-dimensional cases, are systematically derived, and the proposed NL-FEM formulation is successfully verified against several benchmark problems.The transient heat conduction equation is finally coupled with the proposed TC + TM formulation (one-way coupling) thus enabling the analysis of more realistic situations where the constant heating rate assumption is not valid. The coupled formulation is finally implemented for several test cases and it is demonstrated that, it has a significant influence on pore pressure and porosity evolution (through pore volumetric strain) within the ablative matrix phase.

Enhanced Energy Storage Properties of Four-Layer Composite Films via Strategic Macrointerface Modulation.

Dielectric capacitors play a crucial role in the field of energy storage; however, the low discharged energy density (Ue) of existing commercial dielectrics limits their future applications. Currently, further improvement in the Ue of dielectrics is constrained by the challenge of simultaneously achieving high permittivity (εr) and high breakdown electric field strength (Eb). To address this issue, we designed a series of four-layer poly(vinylidene fluoride) (PVDF)-based composite films comprising three functional layers: a sodium bismuth titanate (NBT) plus PVDF composite (NBT&PVDF) layer to achieve high εr values and a pure PVDF layer and a boron nitride (BN) plus PVDF composite (BN&PVDF) layer to achieve high Eb values. This design synergistically enhanced the εr and Eb values of the composite films by exploiting low-loss macrointerface polarization via adjustment of the functional layer stacking order, as supported by simulation analyses. Ultimately, the composite film with a topmost layer of pure PVDF, followed by an NBT&PVDF layer, another pure PVDF layer, and a BN&PVDF layer achieved an enhanced Ue value of 26.42 J·cm-3 and excellent efficiency of 80.03% at an ultrahigh Eb value of 770 MV·m-1. This approach offers an innovative pathway for developing advanced energy storage composite dielectrics via macrointerface manipulation.

Natural and agricultural disturbances differentially impact seedling emergence from soil seed banks in hyperarid ecosystems

Saudi Arabia has implemented ambitious environmental protection programs by creating numerous nature reserves throughout the country. Establishment of the latter nature reserves has led to farm abandonment and the initiation of ecosystem recovery processes. Agricultural practices are known to impact the structure and physicochemical properties of soils while also often markedly affecting natural ecosystem restoration processes. Moreover, weed proliferation in crop fields may modify soil seed banks (SSB), thereby impacting subsequent vegetation recovery. Therefore, it is essential to assess SSB compositions in degraded sites, such as abandoned farms (AF), so as to identify weed species and design efficient restoration strategies in hyperarid ecosystems. In this study, SSB compositions in upper and deep soil layers, standing vegetation compositions, and soil chemical properties were analyzed and compared for two natural ecosystems (NE), two abandoned orchards (AO), two AF, and two natural evaporite basins (EB). NE, AO, AF, and EB all exhibited similar chemical properties, suggesting that former agricultural activities have been guided by a fine understanding of the local environments. Agriculture had impacted the species composition of the observed standing vegetation and germinable SSBs, which could be partly explained by soil property modifications. The findings highlighted that SSBs would warrant detailed study prior to designing ecological restoration strategies, and that the drivers of horizontal and vertical weed dissemination in hyperarid ecosystems should also be explored to gain further insight into weed proliferation patterns and to adapt restoration strategies accordingly.

High Safety Fuel Cells Based on Gas Diffusion Layer Suppressed Uneven Current and Thermal Runaway

AbstractThermal runaway poses a critical safety concern for fuel cells, significantly impairing their performance and durability. Uneven current often leads to uneven temperature, exacerbating the risk of thermal runaway. The inadequate electrical and thermal conductivity of the gas diffusion layer (GDL) is identified as the primary cause of the safety issues. To address this, a multilayer composite gas diffusion layer (MC‐GDL) is proposed and designed to enhance both electrical and thermal conductivity. The in‐plane electrical conductivity of the MC‐GDL reaches an impressive 9.1 × 104 S m−1. Under extreme uneven current, the fuel cell's performance with MC‐GDL only declines by 3.7%, compared to a substantial 58.1% decline observed with commercial GDL. Additionally, the in‐plane thermal conductivity of the MC‐GDL is notably high at 337.0 W m−1 K−1. Under extreme uneven temperature, the maximum temperature of Nafion membrane in fuel cell equipped with MC‐GDL is only 84.2 °C significantly lower than the 180.7 °C observed with commercial GDL. Consequently, the MC‐GDL effectively prevents the melting, thinning, and perforation of the Nafion membrane, thereby mitigating thermal runaway. Furthermore, the superior electrical and thermal conductivity of MC‐GDL can enhance the safety of other electrochemical devices by minimizing uneven current and thermal runaway.

Experimental Research on Basalt Fabric-Based Composites for Protection Against Contact Heat

ABSTRACT The unique properties of basalt fibers, i.e. low thermal conductivity, thermal resistance up to 800°C, biodegradability, resistance to acids and alkalis, corrosion, ultraviolet radiation, and non-flammability, make them increasingly used in personal protective equipment. The design and production of basalt fabric-based composites were performed, and composite layers were directly modified by depositing thin coatings using the magnetron sputtering method. The designing and testing were performed in five stages. For direct basalt fabric modification and basalt fabric-based composites, resistance to contact heat was tested for contact temperatures of 100°C and 250°C. Moreover, the uncertainty budgets of the threshold time measurement results were determined and analyzed for all composites. New basalt fabric-based composites were designed to protect users from contact heat in hot work environments. As a result of the research, it was found that applying composite coatings: aluminum and zirconium dioxide or aluminum and zirconium dioxide and titanium dioxide to both composite layers proved to be effective in obtaining composites that guarantee perfect resistance to contact heat up to 250°C.

Emulsion Structural Remodeling in Milk and Its Gelling Products: A Review.

The fat covered by fat globule membrane is scattered in a water phase rich in lactose and milky protein, forming the original emulsion structure of milk. In order to develop low-fat milk products with good performance or dairy products with nutritional reinforcement, the original emulsion structure of milk can be restructured. According to the type of lipid and emulsion structure in milk, the remolded emulsion structure can be divided into three types: restructured single emulsion structure, mixed emulsion structure, and double emulsion structure. The restructured single emulsion structure refers to the introduction of another kind of lipid to skim milk, and the mixed emulsion structure refers to adding another type of oil or oil-in-water (O/W) emulsion to milk containing certain levels of milk fat, whose final emulsion structure is still O/W emulsion. In contrast, the double emulsion structure of milk is a more complicated structural remodeling method, which is usually performed by introducing W/O emulsion into skim milk (W2) to obtain milk containing (water-in-oil-in-water) W1/O/W2 emulsion structure in order to encapsulate more diverse nutrients. Causal statistical analysis was used in this review, based on previous studies on remodeling the emulsion structures in milk and its gelling products. In addition, some common processing technologies (including heat treatment, high-pressure treatment, homogenization, ultrasonic treatment, micro-fluidization, freezing and membrane emulsification) may also have a certain impact on the microstructure and properties of milk and its gelling products with four different emulsion structures. These processing technologies can change the size of the dispersed phase of milk, the composition and structure of the interfacial layer, and the composition and morphology of the aqueous phase substance, so as to regulate the shelf-life, stability, and sensory properties of the final milk products. This research on the restructuring of the emulsion structure of milk is not only a cutting-edge topic in the field of food science, but also a powerful driving force in promoting the transformation and upgrading of the dairy industry to achieve high-quality and multi-functional dairy products, in order to meet the diversified needs of consumers for health and taste.

Optimization of High Performance Hybrid Composite under Ballistic Test and Performance of the Hybrid Composite under IED Blast

Abstract In this investigation a novel material has been developed comprising of Silicon Carbide (ceramic), Aluminium honeycomb (metal) and Poly Ether Ketone (PEK) – Poly Phynelene Benzobisoxaole (PBO) fiber based blast proof composite. The experimental results proved that this polymeric composite is highly suitable for 9mm pistol bullet with 430 m/sec at distance of 5 m as well as for Improvised Explosive Devices (IED) blast to absorb the sharpnels/ splinters. This investigation also highlights an efficient back layer for a blast-proof sandwich composite. Layer optimization was carried out by FEM analysis of blast effect on the multi-layer polymer composite panel by ANSYS Explicit Dynamics (LS DYNA Solver). The resultant optimal layers of PEK-PBO composites then tested to validate results of FEM analysis. Experimentally it is proved that polymeric composite with 10 layers of PBO fabric when test fired under 9mm pistol bullet with 430 m/sec at distance of 5 m, the bullet penetrates, however, when the polymeric composite is made with a total of 20 layers of PEK-PBO fabric, all the test fired bullets are stopped. Therefore, under SNANAG 4569 blast test, the polymeric composite was essentially made with 20 layers of PBO fabric and it is experimentally proved that PEK-PBO composite is highly efficient as the back layer of hybrid composite and all the sharpnels of IED blast are completely absorbed.

Enhancing anti-adhesion properties by designing microstructure - the microscopy and spectroscopy study of the intercellular bacterial response.

This study is the first one that investigates in detail the bacterial intercellular response to the high density of crystallographic defects including vacancies created in Cu by high pressure torsion. To this aim, samples were deformed by high pressure torsion and afterward, their antibacterial properties against Staphylococcus aureus were analyzed in adhesion tests. As a reference an annealed sample was applied. To avoid the influence of surface roughness, specially elaborated conditions for surface preparation were employed, which do not introduce defects and assure comparable surface roughness. The analysis of the chemical composition and thickness of passive layers by X-ray photoelectron spectroscopy showed that they were comparable for nanostructured and micrograined samples, consisting of Cu2O and CuO, and a thickness of 6nm. The interface bacterium-substrate was prepared by a focused ion beam and further analyzed by scanning transmission electron microscopy and energy dispersive spectroscopy. High pressure torsion processed Cu shows enhanced anti-adhesion properties while in contact with S. aureus than micrograined Cu. There is a linear correlation between luminous intensity and grain size-0.5. The bacterial intercellular defence mechanism includes the creation of Cu2O nanoparticles and the increased concentration of sulphur-rich compounds near these nanoparticles.

Inductive Frequency-Coded Sensor for Non-Destructive Structural Strain Monitoring of Composite Materials

Structural composite materials have gained significant appeal because of their ability to be customized for specific mechanical qualities for various applications, including avionics, wind turbines, transportation, and medical equipment. Therefore, there is a growing demand for effective and non-invasive structural health monitoring (SHM) devices to supervise the integrity of materials. This work introduces a novel sensor design, consisting of three spiral resonators optimized to operate at distinct frequencies and excited by a feeding strip line, capable of performing non-destructive structural strain monitoring via frequency coding. The initial discussion focuses on the analytical modeling of the sensor, which is based on a circuital approach. A numerical test case is developed to operate across the frequency range of 100 to 400 MHz, selected to achieve a balance between penetration depth and the sensitivity of the system. The encouraging findings from electromagnetic full-wave simulations have been confirmed by experimental measurements conducted on printed circuit board (PCB) prototypes embedded in a fiberglass-based composite sample. The sensor shows exceptional sensitivity and cost-effectiveness, and may be easily integrated into composite layers due to its minimal cabling requirements and extremely small profile. The particular frequency-coded configuration enables the suggested sensor to accurately detect and distinguish various structural deformations based on their severity and location.

The Identification of Microstructural Changes in High-Temperature Superconducting Tapes for Superconducting Fault Current Limiters

HTS 2G tapes used in Superconducting Fault Current Limiters (SFCLs) have properties that allow for the effective limitation of short-circuit currents; however, due to the specificity of the device operation, they should be characterized by the high stability of the parameters when repeatedly leaving the superconducting state. During the operation of SFCLs, a situation may occur in which the parameters of the HTS tapes used will change several times as a result of the action of short-circuit currents that exceed the critical current IC of the superconductor of the tape used. This paper presents the results of microstructural tests of 2G HTS tapes intended for SFCLs, subjected to surge currents corresponding to prospective short-circuit currents with values higher than their critical currents IC and for which IC changes were observed. The HTS tapes were examined using a JEOL 7600F field emission scanning electron microscope (SEM), and their chemical composition was analyzed using Energy-Dispersive X-ray Spectroscopy (EDS). The test results indicate the possibility of micro-damage in the form of cracks in the superconductor layer, as well as the interruption of the buffer layers and the oxidation of the silver layers. The analysis of the chemical composition of the HTS tape layers may indicate the occurrence of diffusion processes.

Molecular Dynamics Simulation of Temperature and Ti Volume Fraction on Compressive Properties of Ti/Al Layered Composites

Molecular Dynamics Simulation of Temperature and Ti Volume Fraction on Compressive Properties of Ti/Al Layered Composites

Microbial imbalance in Darier disease: Dominance of various staphylococcal species and absence of Cutibacteria

Darier disease (DD) is a rare autosomal dominant genodermatosis characterized by erythematous papules and plaques mainly involving sebaceous areas, such as the face, chest and back. Skin microbiome plays an essential role in maintaining skin homeostasis. A disturbed skin microbiome may contribute to the exacerbation of DD. We investigated the bacterial composition of two predilectional sites in DD patients and healthy individuals. We also measured the microbiome composition of deeper skin layers, where diversity was significantly reduced compared to the superficial layer of the skin from the same area. The microbiome of DD patients at lesional sites differed from that of non-lesional skin areas; moreover, non-lesional sites were different from those of the controls. Lesional areas were dominated by Staphylococcus species, such as S. aureus, S. epidermidis, S. hominis, S. sciuri, and S. equorum. However, levels of Cutibacterium acnes (formerly Propionibacterium acnes) and C. acnes subspecies defendens were significantly lower in lesional sites than in non-lesional sites. A significant decrease was measured in the levels of these two bacteria between non-lesional and control samples. Our findings may indicate that alterations in the skin microbiome could contribute to the inflammation of skin lesions in DD.

Regulating Anode-Electrolyte Interphasial Reactions by Zwitterionic Binder Chemistry in Lithium-Ion Batteries with High-Nickel Layered Oxide Cathodes and Silicon-Graphite Anodes.

The practical application of silicon (Si)-based anodes faces challenges due to severe structural and interphasial degradations. These challenges are exacerbated in lithium-ion batteries (LIBs) employing Si-based anodes with high-nickel layered oxide cathodes, as significant transition-metal crossover catalyzes serious parasitic side reactions, leading to faster cell failure. While enhancing the mechanical properties of polymer binders has been acknowledged as an effective means of improving solid-electrolyte interphase (SEI) stability on Si-based anodes, an in-depth understanding of how the binder chemistry influences the SEI is lacking. Herein, a zwitterionic binder with an ability to manipulate the chemical composition and spatial distribution of the SEI layer is designed for Si-based anodes. It is evidenced that the electrically charged microenvironment created by the zwitterionic species alters the solvation environment on the Si-based anode, featuring rich anions and weakened Li+-solvent interactions. Such a binder-regulated solvation environment induces a thin, uniform, robust SEI on Si-based anodes, which is found to be the key to withstanding transition-metal deposition and minimizing their detrimental impact on catalyzing electrolyte decomposition and devitalizing bulk Si. As a result, albeit possessing comparable mechanical properties to those of commercial binders, the zwitterionic binder enables superior cycling performances in high-energy-density LIBs under demanding operating conditions.

Solidification behavior of WC particles reinforced nickel alloy cladding layers by plasma surfacing: Simulation and experiment

In this work, a numerical simulation model was developed to investigate the complex heat and mass transfer process inside the molten pool during plasma surfacing. The temperature distribution and fluid flow were employed to depict the evolution of the molten pool. The findings revealed that the maximum temperature is located on the surface of the cladding layer corresponding to the position of heat source, and the temperature distribution follows a Gaussian distribution along the scanning direction. Thermal accumulation is obvious due to the continuous energy input in the initial stage, as a result, the maximum temperature and fluid flow velocity gradually increase with the deposition process. The maximum temperature and fluid flow velocity at 4.0 s are 1893 K and 0.281 m/s in case 110 A, respectively. The predicted shapes and dimensions are consistent with the results of the deposition experiments, with a maximum error of no more than 15 %. In order to investigate the impact of WC particles on the solidification microstructure of nickel composite layers, corresponding plasma surfacing experiment was implemented. The solidification characteristics of the microstructure follow planar-cellular-columnar-equiaxed crystals in the bonding layer and WC particles-columnar-equiaxed dendritic crystals in hard layer, respectively. Furthermore, the Ni dendritic near the retained WC particles transformed into columnar crystals due to temperature gradient in the local area.