Advanced Composites Research Articles

Fabrication of advanced polyphenylene sulfide composites by in-situ grafting of sulfide silane and PCPA on glass fibers

The energy crisis has driven increased adoption of electric vehicles (EVs) in the automotive sector, with a focus on lightweight engineering plastics (EPs) for fuel efficiency. This study aims to enhance the mechanical properties and thermal conductivity of EPs to address heat-related concerns in EVs and electronic devices. A hybrid filler (milled glass fiber, boron nitride, and graphene oxide) was introduced to polyphenylene sulfide (PPS), using a simultaneous grafting process with poly(catechol/polyamine) (PCPA) and silane additives. Filler aggregation in the resin matrix was overcome with surface-treatment agents such as Bis[3-(triethoxysilyl)propyl] tetrasulfide (Si69), catechol, and tetraethylenepentamine. PCPA polymerization on the filler surfaces bridged connections between fillers and silane molecules. The resulting surface-treated hybrid composite showed a 637% increase in thermal conductivity (2.102 Wm−1K−1) and a 63.94% increase in tensile strength (65.87 MPa) compared to the base matrix. Incorporating 40 wt.% surface-treated mGF, 30wt.% raw BN, and 6wt.% surface-treated GO, along with PCPA and Si69 treatments, achieved this improvement. The hybrid filler composites significantly enhanced thermal conductivity and mechanical properties, providing a rapid and convenient solution to challenges in robustness and heat dissipation for electronic vehicles and devices.

Short-term anticorrelations between in situ averaged charge states of Fe and O in the solar wind

Observations of the Fe and O charge states in the solar wind and interplanetary coronal mass ejections (ICMEs) generally exhibit a positive correlation between the average charge states of Fe and O ($ avQ Fe $ and $ avQ O $). Because Fe and O charge states freeze at different heights in the corona, this positive correlation indicates that conditions at different heights in the corona vary as a whole. We identify short time periods in the solar wind that exhibit anticorrelations between the average Fe and O charge states and investigate their properties. We aim to distinguish whether these anticorrelations are due to the related solar sources or to transport effects (e.g., differential streaming). We study kinetic properties of the solar wind related to these anticorrelated structures as well as heavy ion differential streaming in order to infer a possible relationship between conditions in coronal source regions and the reported in situ measurements. We employed a recently developed sliding-window cross-correlation method to locate anticorrelated structures in the solar wind composition measurements between 2001 and 2010 from the Advanced Composition Explorer (ACE). To account for fluctuations and measurement uncertainties, we varied the timescales and temporal lags. We determined the onset and end times of the gradual increases or decreases in the average charge states of O and Fe and analyzed the kinetic and plasma properties of the anticorrelated structures. We identified 103 anticorrelated structures both in the solar wind and in ICMEs. The behavior of $ avQ Fe $ is strongly related to solar wind kinetic properties, including proton speed, proton temperature, and the proton-proton collisional age. We find that the anticorrelation of $ avQ Fe $ and $ avQ O $ during these time periods cannot be explained by differential streaming nor by unrecorded hot plasma ejections. Thus, the measured anticorrelated variations in $ avQ Fe $ and $ avQ O $ probably indicate that changes in coronal conditions at different freeze-in heights may follow opposite monotonic trends.

Tumoroid-On-a-Plate (ToP): Physiologically Relevant Cancer Model Generation and Therapeutic Screening.

Employing three-dimensional (3D) in vitro models, including tumor organoids and spheroids, stands pivotal in enhancing cancer therapy. These models bridge the gap between two-dimensional (2D) cell cultures and complex in vivo environments and offer versatile tools for comprehensive studies into cancer progression, drug responses, and tailored therapies. This study introduces the Tumoroid-on-a-Plate (ToP) device, an innovative ope-surface microfluidic platform designed to create predictive 3D models of solid tumors. The ToP device combines tumor mass, stromal cells, and extracellular matrix (ECM) components, to closely replicate the microenvironment of glioblastoma (GBM) and pancreatic adenocarcinoma (PDAC). Using the advanced ToP model and testing various GBM ECM compositions such as collagen and Rreelin within the model, we can assess how specific elements affect GBM invasiveness. The ToP in vitro model also enables screening chemotherapeutics such as temozolomide and iron-chelators in a single and binary treatment setting on the complex ECM-embedded tumoroids to evaluate their toxicity on GBM and PDAC models viability and apoptosis. Furthermore, co-culturing PDAC tumoroids with human-derived fibroblasts reveals the pro-invasive influence of stromal elements on tumor growth and drug response. This research underscores the value of advanced 3D models like ToP in advancing the understanding of cancer complexity and therapy responses.

Advancements in Biofiller-Reinforced PLA Composites for 3D Printing: A Review

Additive manufacturing is key in realizing highly complex and high-performance composite materials. Among all the various kinds of functionality that could be added to a composite component, continuous fiber-reinforced composites have been drawing much attention because of their attractive combination of properties. The comprehensive spectrum of knowledge that ranges from the basics concerned with structure, morphology, synthesis, physical, and chemical properties finally reaches to this analytical study of advanced composites. Most generally, such a composite is structured on a thermoplastic or thermoset polymer matrix that embeds the load-carrying reinforcing fibers; probably best known are carbon, glass, and aramid fibers. These composites, which involve fibers continuously reinforcing, have high strength relative to their weight. They are also anisotropic, meaning they have qualities that vary from one direction to another – something which might be customisable for specific load cases. They warp and shrink less during their life in an outside environment than conventionally made bioplastics due to a fact that short fibers can provide reinforcement to them. This 3-D printing object is manufactured by special additive manufacture technology during the manufacturing process after compounding and extruding the fiber-reinforced composite filament. The final properties of 3D printed parts could be tailorable through changing variables such a fiber type, fiber length, volume fraction, polymer matrix material, orientation of fibers, and printing process parameters. These continuous fiber-reinforced 3D printed composites could achieve tensile strengths up to one GPa, have stiffness values reaching even a rating of countless Gpa, and have ad thicknesses in the range from about 1.4–1.8 g/cm³. This finding could be applied in basically all major industries, from aerospace and the automotive industry to sports gear. Such conclusions from the analysis may be useful in the selection of appropriate materials and techniques while even guiding the development of new applications with respect to such advanced composite materials.

Application of machine learning algorithm and Carrera unified formulation in thermal buckling analysis of a functionally graded graphene origami enabled auxetic metamaterial sandwich plate with an auxetic concrete foundation

This study presents a comprehensive thermal buckling analysis of sandwich plates composed of functionally graded graphene origami-enabled auxetic metamaterial (FG-GOEAM) face sheets on an auxetic concrete foundation, using Carrera’s unified formulation (CUF) as the theoretical framework. FG-GOEAM materials are emerging as advanced composites, combining exceptional mechanical resilience, tunable auxetic behavior, and high thermal stability, making them suitable for extreme environments. By employing CUF, a powerful and adaptable modeling approach, this work accurately captures the complex mechanical interactions within the FG-GOEAM sandwich structure under thermal loads, incorporating both material gradation and auxetic properties. To further enhance the precision and efficiency of this thermal buckling analysis, a deep neural network (DNN) is developed as a machine learning algorithm to predict critical temperature differences, based on a dataset generated through mathematics simulation. The DNN model demonstrates excellent predictive capability, validated by close alignment between its estimates and CUF results, thus reducing computational costs while maintaining high accuracy. Parametric studies are conducted to assess the effects of material gradation, aspect ratios, and foundation properties on thermal buckling performance. The results highlight the superior thermal stability of FG-GOEAM structures and the potential of DNNs to serve as reliable, computationally efficient tools for advanced structural analysis. This study provides a novel, integrated framework for high-fidelity thermal buckling prediction in complex auxetic composites, paving the way for broader applications in engineering fields requiring lightweight, thermally stable structures.

The State of Solar Wind Heavy Ions in Interplanetary Coronal Mass Ejection–Driven Geomagnetic Storms

During geomagnetic storms, which are the primary periods for heavy ions from the solar wind to enter Earth’s magnetospheric space, the charge state of solar wind heavy ions during these storms has significant implications for studying the distribution and effects of heavy ions in the magnetosphere. We analyzed the states and variations of heavy ions during 158 interplanetary coronal mass ejection (ICME)–driven geomagnetic storm events using data from the Advanced Composition Explorer satellite and examined four of these events in detail. We found that the increase in the average charge state of heavy ions such as O, Mg, Si, and Fe is positively correlated with the intensity of the geomagnetic storm. Regarding the abundance ratio of heavy ions such as Ne, Mg, Si, and Fe relative to oxygen ions, the rate and magnitude of increase in abundance ratios during extreme geomagnetic storms (Kp = 9) triggered by ICME events are significantly higher than those during other levels of geomagnetic storms. Additionally, we observed that although the average charge states of heavy ions such as O and Fe are correlated with the geomagnetic storm intensity induced by ICMEs, there are significant individual differences in the charge state variations of heavy ions.

An Extensive Study of Metal Matrix Composites and their Various Properties for Different Uses

This study examines the creation and development of composite materials, from conventional techniques to their innovative uses in numerous industries. Composite materials that are robust, versatile, and resilient have advanced significantly, especially with the application of nanotechnology and hybrid fiber reinforcements. Composite materials are difficult to machine due to their anisotropic and non-homogeneous structure, as well as the high abrasiveness of their reinforcing parts. This typically results in the workpiece becoming damaged and the cutting tool wearing down very rapidly. On composite materials, traditional machining methods such as turning, drilling, and milling can be applied with the appropriate tool design and operating parameters. An overview of the various issues related to the conventional machining of the main types of composite materials is given in this work. This article examines novel matrix materials, forms of reinforcement, and production procedures to show how advanced metallic matrix nano composites and fiber-reinforced polymers are replacing traditional composites. Special emphasis is given to the strict manufacturing conditions in addition to the homogenous dispersion of nanoparticles and damage-free machining of fiber composite materials. The essay also discusses how sustainable alternatives, including reinforcements made of natural fibers, affect the ecosystem. This study aims to offer a comprehensive analysis and case studies.

Innovative upcycling cigarette filters into high-performance cellulose nanofiber-epoxy composites

This research introduces a novel upcycling method for transforming cigarette filters—an abundant and persistent environmental waste—into high-performance epoxy composites reinforced with cellulose nanofibers. The innovation lies in extracting cellulose acetate nanofibers from used cigarette butts via a multi-step purification and electrospinning process, followed by their conversion into regenerated cellulose nanofibers through alkaline hydrolysis. This dual-fiber approach allows us to fabricate four distinct epoxy composites, each reinforced by different nanofiber types: recycled cellulose acetate nanofibers, regenerated cellulose nanofibers from recycled cigarette filters, and their commercial counterparts. Notably, this is the first time regenerated nanofibers derived from waste cigarette filters have been utilized for epoxy composite reinforcement, demonstrating a sustainable, high-value use for a major pollutant. Comprehensive characterizations, including FTIR, XRD, SEM, and contact angle measurements, confirmed the successful regeneration of cellulose nanofibers, showing improved hydrophilicity, reduced crystallinity, and uniform nanofiber morphology with diameters between 200 and 300 nm. The innovation further extends to the mechanical performance of these composites: tensile tests revealed that those reinforced with regenerated cellulose nanofibers exhibited superior tensile strength (49.5–53.8 MPa), significantly outperforming both cellulose acetate nanofiber composites (40.1–42.6 MPa) and neat epoxy resin (31.4 MPa). This marked improvement is attributed to enhanced nanofiber dispersion and interfacial adhesion within the epoxy matrix, an essential advancement over traditional composites. In addition, thermal analysis showed that all composites maintained thermal stability in the 300–400 °C range, comparable to commercial alternatives. The regenerated nanofiber-reinforced composites also displayed enhanced optical transparency due to reduced light scattering, making them ideal candidates for applications requiring both mechanical strength and optical clarity. By pioneering the use of cigarette filter waste for fabricating advanced cellulose nanofiber composites, this study presents an eco-friendly approach to addressing environmental pollution while creating sustainable materials with superior mechanical, thermal, and optical properties.

One-Step laser induced molybdenum carbide/graphene hybrid electrode for supercapacitor

Transition metal carbides (TMCs) have garnered significant attention in various energy applications owing to their outstanding conductive and electrochemical properties. Despite these advantages, challenges persist in terms of non-toxicity and efficient fabrication methods. In this study, a Mo3C2/laser-induced graphene (LIG) heterostructure was synthesized via one-step CO2 laser induced conversion process. The specific area capacitance of the Mo3C2/LIG hybrid electrode reached 23.5 mF cm−2, which is 2.5 times higher than that of pure Mo3C2 and 9 times greater than pure LIG electrodes. Moreover, the hybrid electrode exhibited robust cycling stability, maintaining 98.4 % of its initial capacitance after 10,000 charge–discharge cycles. Theoretical simulation also revealed superior hydrogen adsorption and high electrical conductivity of the Mo3C2/LIG hybrid electrode. This work presents a promising approach for developing advanced molybdenum carbide-based composites and offers an alternative strategy for enhancing the electrochemical performance of capacitive electrodes.

A Numerical Framework of Simulating Flow-Induced Deformation during Liquid Composite Moulding

Fibre deformation (or shearing of yarns) can develop during the liquid moulding of composites due to injection pressures or polymerisation (cross-linking) reactions (e.g., chemical shrinkage). On that premise, this may also induce potential residual stress–strain, warpage, and design defects in the composite part. In this paper, a developed numerical framework is customised to analyse deformations and the residual stress–strain of fibre (at a micro-scale) and yarns (at a meso-scale) during a liquid composite moulding (LCM) process cycle (fill and cure stages). This is achieved by linking flow simulations (coupled filling–curing simulation) to a transient structural model using ANSYS software. This work develops advanced User-Defined Functions (UDFs) and User-Defined Scalers (UDSs) to enhance the commercial CFD code with extra models for chemorheology, cure kinetics, heat generation, and permeability. Such models will be hooked within the conservation equations in the thermo-chemo-flow model and hence reflected by the structural model. In doing so, the knowledge of permeability, polymerisation, rheology, and mechanical response can be digitally obtained for more coherent and optimised manufacturing processes of advanced composites.

Determining the Interstellar Wind Longitudinal Inflow Evolution Using Pickup Ions in the Helium Focusing Cone

The size, shape, and composition of the heliosphere are affected by its interaction with the local interstellar medium. A means of quantifying this interaction is by measuring the relative motion of the two media. We determine the flow direction, λISN , of the interstellar wind through the heliosphere and its trend over an 11 yr solar cycle using Advanced Composition Explorer/Solar Wind Ion Composition Spectrometer He+ double-coincidence pickup ion (PUI) measurements from a data set spanning 13 full orbits, with focusing cone crossings occurring between the years 1998 and 2010. We measure the flow direction by fitting a kappa function to the focusing cone signature in the count rates of He+ at the PUI cutoff measured as a function of ecliptic longitude. We determine λISN for each three-orbit boxcar centered on the years 1999 through 2009 and find the trend of the resulting linear fit. We account for solar transients by removing measurements associated with CMEs. However, there still may be effects from compression regions, such as stream–stream and corotating interaction regions. We additionally make considerations to ensure the PUI torus is in view, to account for varying interplanetary magnetic field angles, to ensure that we analyze newly injected interstellar PUIs largely unaffected by transport effects, and to account for general solar activity. We measure a slope in the flow direction to be 0.00° ± 0.51°​​​​ yr−1, indicating that we do not measure a varying trend over this period. We repeat the focusing cone analysis for the combined data set and determine an overall flow direction of 75.37° ± 0.43°.

In-plane electrical conductivity of PEDOT:PSS/Halloysite composite thin films

PEDOT:PSS has found numerous applications in the field of advanced materials, especially in the development of organic electronics. Embedding nanoparticles into the polymer matrix has emerged as an effective strategy to modify the properties of PEDOT:PSS and develop advanced functional composites. Over the past decade, Halloysite nanotubes (HNT) have garnered significant interest and utility as nanofillers and/or templates due to their unique physical-chemical properties, small size, relatively low cost, and large availability. Interestingly, pairing PEDOT:PSS with non-conductive HNT has been demonstrated to enhance the charge transport properties of the composite film. Our discoveries show how the HNT can act as scaffolding for PEDOT:PSS by improving the local ordering of PEDOT chains and enabling the formation of conductive pathways. Consequently, the mechanism responsible for the observed changes in conductivity and the correlation between PEDOT:PSS and insulating nanofillers (HNT) could be different to that previously proposed. Hence, in this work it was observed that PEDOT:PSS/HNT composite films exhibited a non-linear conductivity dependence as a function of the HNT loading. From thermogravimetric analysis, infrared and UV-Vis-NIR spectroscopies, as well as impedance spectroscopy, a more complex interaction between the polymer chains and the nanotubes is revealed. Our study includes the modification of the interaction between the PEDOT chains and the nanofillers by using the secondary doping effect and functionalization of the nanotubes, which confirms our findings. These results represent a significant progress toward a deeper understanding of the emergence of a conductive polymer network on the nanofiller surface, leading to improvements in the electrical conductivity in the composite material.

Probing the formation mechanism of hierarchical microstructures in experimental Ni-based superalloys

Hierarchical microstructures, consisting of a γ matrix with γ′ precipitates that incorporate finer-scale embedded γ precipitate, are known to enhance strength and enhanced coarsening resistance of the ordered γ′ precipitates in various nickel-based superalloys. Despite their potential benefits, the underlying origins and design principles of such hierarchical microstructures remain poorly understood due to the complex multicomponent nature of superalloys. In this study, we employ an integrated approach that combines advanced composition and microstructure analysis and computational thermodynamic and kinetic modeling to investigated the formation mechanism of the hierarchical microstructure in two experimental multi-component nickel-base superalloys. Using chemical mapping via atom probe tomograph and nucleation driving force calculations, we find that the enrichment of γ-stabilizing elements, such as Co and Cr, along with the depletion of Al within the γ′ precipitates, promotes the decomposition of the γ′ phase and the precipitation of the finer γ phase. In addition, kinetic modeling predicts the supersaturation of Co and Cr during cooling, elucidating the influence of heat treatment on solute partitioning. Our findings illustrate how alloy composition and tailored heat treatment strategies discussed can guide the design of a hierarchical γ/γ’/γ microstructure, offering a pathway towards optimizing mechanical properties in nickel superalloys through microstructure design.

Longitudinal Extent of 3He-rich Solar Energetic Particle Events Near 1 au

Multispacecraft observations of 3He-rich solar energetic particle (SEP) events are scarce, but much needed in order to understand and properly constrain the source and transport of these remarkably enriched 3He SEP events. In this paper, we report 15 3He-rich SEP events that were detected by the Advanced Composition Explorer, the Solar Terrestrial Relations Observatory, and Solar Orbiter near 1 au during Solar Orbiter’s aphelion pass at the end of 2022 and early 2023. Three (five) of these events were detected simultaneously by at least two (three) spacecraft at up to ∼40° longitudinal separation, while seven events were detected by only a single spacecraft, even though an adjacent spacecraft was less than 20° apart. Using a magnetic connectivity tool, we show statistically that there is a >50% probability of detection when the spacecraft-modeled footpoints have an angular separation angle of <24° to the potential source region back at the Sun. This supports previous studies suggesting that the source of these 3He-rich SEP events is narrow in longitudinal extent. On the other hand, the magnetic connectivity due to the presence of coronal mass ejections, footpoint motion, and/or field-line meandering may also lead to difference in a detection at 1 au.

DEVELOPMENT OF ADVANCED COMPOSITIONS INCORPORATING WOLLASTONITE, THERMOVERMICULITE, SILICON IV OXIDE, AND AEROSIL

This study presents the development of innovative composite materials by incorporating wollastonite, thermovermiculite, silicon IV oxide (SiO₂), and aerosil. The primary objective was to formulate high-performance materials with enhanced mechanical, thermal, and structural properties suitable for industrial and construction applications. Wollastonite and thermovermiculite, known for their excellent reinforcing properties, were combined with SiO₂ and aerosil to create a hybrid matrix. The materials were synthesized and characterized using techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA). Experimental results revealed that the new compositions exhibited superior heat resistance, improved strength, and enhanced durability compared to traditional materials. The inclusion of aerosil, with its fine particle size and high surface area, contributed to improved dispersion and homogeneity within the matrix, resulting in enhanced thermal stability and mechanical performance. These advanced composites hold great potential for applications in areas requiring robust thermal and structural integrity, including insulation, construction materials, and high-temperature industrial components. Future work will focus on further optimizing these formulations and exploring their use in specialized engineering fields.

Spectral Properties and the Influence of Coronal Mass Ejections in 3He-rich Solar Energetic Particle Events

We analyze the spectral properties of 3He and 4He as well as the heavy ions (oxygen, neon, magnesium, silicon, and iron) in 80 3He-rich solar energetic particle (SEP) events observed by the Ultra-Low-Energy Ion Spectrometer on board the Advanced Composition Explorer spacecraft since its launch in 1997 until 2024. We split the spectral analysis into two criteria: events with fast and wide coronal mass ejections (CMEs; called “FW events”) and events with slow, narrow, or no observed CMEs (called “non-FW events”). Overall, we find that events with fast and wide CMEs exhibit more uniform spectra across all species, and their low-energy spectral indices are strongly correlated, suggesting a CME provides an additional reacceleration mechanism for the 3He-rich SEPs. When comparing each species’ low-energy spectral index for events with no associated fast-and-wide CME, we find a primary peak in the spectral hardness of 3He, and a secondary peak in Mg and Si. If we consider a plasma temperature of 1.0–1.3 MK, Mg and Si have a charge-to-mass ratio (Q/M) nearest to one-third (1/3), directly half that of 3He. Thus, our results support the results of Roth & Temerin, which suggest heavy ions resonate with the second harmonic of the same ion cyclotron waves energizing 3He. However, it is unclear why the Fe enhancement is not reflected in its spectral index, and we propose that additional acceleration and/or transport mechanisms are playing a role in the abundance enhancement of Fe and heavier ions.

Enhancing road safety with the infrastructure-adaptable NDBA 2.0 concrete median barrier: An Italian experience

Road safety is a crucial global concern because of the high number of fatalities and injuries resulting from road crashes each year. Median crossover collisions are among the most dangerous crashes that happen on highways, frequently leading to serious or fatal injuries. The main approach to decreasing the occurrence of these types of crashes is the installation of median barriers. When the need for such installations arises, road agencies must choose from various options, including concrete barriers, cable barriers, or metal-beam guardrails. This paper is dedicated to the New Dynamic Barrier for Highways (NDBA 2.0), an innovative technology for median barriers developed by the Italian National Road Agency (ANAS), emphasizing its pivotal role in enhancing road safety. It incorporates high-tensile steel and advanced composites, offering robust protection while maintaining a lightweight profile. What distinguishes the NDBA 2.0 is its dynamic nature, featuring an intelligent system that seamlessly adapts to the road infrastructure. Its modular construction, with sections of only 200 cm, allows for easy installation and ensures compatibility across successive road segments. This adaptability reduces construction time while maintaining the highest standards of performance. From a road safety perspective, the NDBA 2.0 offers substantial advantages. Its design contributes to minimizing crash-related costs by reducing the severity of crashes, particularly in the transition zones. The barrier's design allows it to adapt to varying road conditions and traffic volumes, effectively addressing common installation challenges on existing roadways as well. Its ability to be directly supported on the road surface wear layer eliminates the need for costly foundation structures, facilitating quick installation and reducing maintenance expenses. The NDBA 2.0 barrier was designed to eliminate the need for future simulations in the design and verification of transitions between different barriers. For this reason, the NDBA 2.0 barrier has been tested in real-world conditions in class H4 and, consequently, is equipped with CE marking. This study offers a comprehensive analysis of the NDBA 2.0 barrier, whose implementation may provide significant benefits for road safety. Continued research, collaboration, and widespread adoption of the NDBA 2.0 barrier can further enhance road safety on a global scale.

Analyzing the pyrolysis mechanism of advanced composites based on nitrotriazolone and energetic cellulose-rich polymers

This study investigated the structure, thermal decomposition, and mechanism of nitrotriazolone (NTO)-based composites. Three types of energetic composites namely, nitrocellulose (NC)/NTO, microcrystalline nitrocellulose (MCCN)/NTO, and carbamate microcrystalline cellulose nitrated (M3CN)/NTO were prepared. The obtained results revealed that NTO particles were homogeneously dispersed or embedded within the modified or unmodified nitrated polymeric chains. This dispersion effectively inhibited the crystal growth of NTO particles, resulting in submicron-sized particles. In addition, the thermolysis of NC, MCCN, and M3CN remained unchanged according to thermal analysis results, while the second temperature peak was significantly lower than that of raw NTO. Notably, the thermolysis of the nitrated polymers (NC, MCCN, and M3CN) occurs independently when combined with NTO. It was found that the release of gaseous species during the initial decomposition phase significantly influenced the thermal profile of NTO, thereby altering its decomposition mechanism. Thermogravimetric analysis coupled with fourier transform infrared spectroscopy (TGA-FTIR) findings highlighted the significant influence of nitrated polymer types on the gaseous products of NTO decomposition, affecting the intensity and the type of nitrogen oxides generated during pyrolysis. These results present a promising fabrication strategy for utilizing NTO-based energetic composites in high-energy propellants and explosives.

Effect of Mo nanoparticles on microstructure and mechanical properties of Cu alloys by self-propagating and spark plasma sintering

Cu alloys strengthened with Mo nanoparticle, with Mo contents of 2 at.%, 4 at.%, 6 at.%, 8 at.%, and 10 at.%, were fabricated by self-propagating high-temperature synthesis, followed by two-step hydrogen reduction and spark plasma sintering. The microstructures, mechanical properties, and thermal conductivity of these Cu-Mo alloys were investigated. The results reveal that two-step hydrogen reduction effectively reduces the average Mo particle size to 13.8 nm compared to one-step reduction. With increasing Mo content, the average grain size of Cu initially decreases but then increases due to the segregation of Mo particles. Notably, the Cu-6 at.% Mo alloy exhibits the smallest average grain size of 0.46 μm, with dispersed nanoscale Mo particles of 25.6 nm. The Cu-6 at.% Mo alloy demonstrates superior mechanical properties, with a tensile strength of 405.0 MPa and an elongation of 24.9 %. Furthermore, the Cu-6 at.% Mo alloy has a high thermal conductivity of 320.0 Wm−1K−1 even at 400 °C and a high electrical conductivity of 82.3 % IACS at room temperature. This work offers valuable insights for the design of advanced Cu composites suitable for heat sink applications.

Longitudinal-Torsional Frequency Coupling Design of Novel Ultrasonic Horns for Giant Magnetostrictive Transducers.

The use of advanced brittle composites in engineering systems has necessitated robotic rotary ultrasonic machining to attain high precision with minimal machining defects such as delamination, burrs, and cracks. Longitudinal-torsional coupled (LTC) vibrations are created by introducing helical slots to a horn's profile to enhance the quality of ultrasonic machining. In this investigative research, modified ultrasonic horns were designed for a giant magnetostrictive transducer by generating helical slots in catenoidal and cubic polynomial profiles to attain a high amplitude ratio (TA/LA) and low stress concentrations. Novel ultrasonic horns with a giant magnetostrictive transducer were modelled to compute impedances and harmonic excitation responses. A structural dynamic analysis was conducted to investigate the effect of the location, width, depth and angle of helical slots on the Eigenfrequencies, torsional vibration amplitude, longitudinal vibration amplitude, stresses and amplitude ratio in novel LTC ultrasonic horns for different materials using the finite element method (FEM) based on the block Lanczos and full-solution methods. The newly designed horns achieved a higher amplitude ratio and lower stresses in comparison to the Bezier and industrial stepped LTC horns with the same length, end diameters and operating conditions. The novel cubic polynomial LTC ultrasonic horn was found superior to its catenoidal counterpart as a result of an 8.45% higher amplitude ratio. However, the catenoidal LTC ultrasonic horn exhibited 1.87% lower stress levels. The position of the helical slots was found to have the most significant influence on the vibration characteristics of LTC ultrasonic horns followed by the width, depth and angle. This high amplitude ratio will contribute to the improved vibration characteristics that will help realize good surface morphology when machining advanced materials.