Search Results (141)

Modern aerospace engineering places increasing emphasis on materials that combine low weight with high mechanical performance. Fiber metal laminates (FMLs), which merge metal layers with fiber-reinforced composites, meet this demand by delivering improved fatigue resistance, impact tolerance, and environmental durability, often surpassing the performance of their constituents in demanding applications. Despite these advantages, inspecting such thin, layered structures remains a significant challenge, particularly when they are difficult or impossible to access. As with any new invention, they always come with challenges. This study examines the effectiveness of the fundamental anti-symmetric Lamb wave mode (A0) in detecting weak interfacial defects within Carall laminates, a type of hybrid fiber metal laminate (FML). Delamination detectability is analyzed in terms of strong wave dispersion observed downstream of the delaminated sublayer, within a region characterized by acoustic distortion. A three-dimensional finite element (FE) model is developed to simulate mode trapping and full-wavefield local displacement. The approach is validated by reproducing experimental results reported in prior studies, including the author’s own work. Results demonstrate that the A0 mode is sensitive to delamination; however, its lateral resolution depends on local position, ply orientation, and dispersion characteristics. Accurately resolving the depth and extent of delamination remains challenging due to the redistribution of peak amplitude in the frequency domain, likely caused by interference effects in the acoustically sensitive delaminated zone. Additionally, angular scattering analysis reveals a complex wave behavior, with most of the energy concentrated along the centerline, despite transmission losses at the metal-composite interfaces in the Carall laminate. The wave interaction with the leading and trailing edges of the delaminations is strongly influenced by the complex wave interference phenomenon and acoustic mismatched regions, leading to an increase in dispersion at the sublayers. Analytical dispersion calculations clarify how wave behavior influences the detectability and resolution of delaminations, though this resolution is constrained, being most effective for weak interfaces located closer to the surface. This study offers critical insights into how the fundamental anti-symmetric Lamb wave mode (A0) interacts with delaminations in highly attenuative, multilayered environments. It also highlights the challenges in resolving the spatial extent of damage in the long-wavelength limit. The findings support the practical application of A0 Lamb waves for structural health assessment of hybrid composites, enabling defect detection at inaccessible depths. Full article

An approach for the formation of intermetallic coatings on the titanium surface based on titanium aluminides is proposed. The approach involves producing a layered steel-aluminum-titanium metal composite via explosive welding, followed by heat treatment to form a diffusion zone at the steel–aluminum interface with a thickness of more than 30 μm, sufficient for the spontaneous separation of the steel layer. As a result, an aluminum layer approximately 0.3 mm thick remains on the titanium surface. Subsequent heating at temperatures of 700–850 °C, below the allotropic transformation temperature of titanium, results in the transformation of the aluminum layer into titanium aluminides. The formation of the intermetallic coating structure occurs as a result of the upward transportation of TiAl₃ fragments separated from the reaction zone by circulating melt flows. With increasing heat treatment time, these fragments become separated by the Al₂O₃ oxide phase. Full article

This report is on Co and Ti substituted M-type barium and strontium hexagonal ferrites that are reported to be single phase multiferroics due to a transition from Neel type ferrimagnetic order to a spiral spin structure that is accompanied by a ferroelectric polarization in an applied magnetic field. The focus here is the nature of magnetoelectric (ME) interactions in the bilayers of ferroelectric PZT and Co and Ti substituted BaM and SrM. The ME coupling in the ferrite-PZT bilayers arise due to the transfer of magnetostriction-induced mechanical deformation in a magnetic field in the ferrite resulting in an induced electric field in PZT. Polycrystalline Co and Ti doped ferrites, Ba (CoTi)_x Fe_12−2xO_19, (BCTx), and Sr (CoTi)_x Fe_12−2xO₁₉ (SCTx) (x = 0–4) were found to be free of impurity phases for all x-values except for SCTx, which had a small amount of α-Fe₂O₃ in the X-ray diffraction patterns for x ≤ 2.0. The magnetostriction for the ferrites increased with applied filed H to a maximum value of around 2 to 6 ppm for H~5 kOe. BCTx/SCTx samples showed ferromagnetic resonance (FMR) for x = 1.5–2.0, and the estimated anisotropy field was on the order of 5 kOe. The magnetization increased with the amount of Co and Ti doping, and it decreased rapidly with x for x > 1.0. Measurements of ME coupling strengths were conducted on the bilayers of BCTx/SCTx platelets bonded to PZT. The bilayer was subjected to an AC and DC magnetic field H, and the magnetoelectric voltage coefficient (MEVC) was measured as a function of H and frequency of the AC field. For BCTx-PZT, the maximum value of MEVC at low frequency was ~5 mV/cm Oe, and a 40-fold increase at electromechanical resonance (EMR). SCTx–PZT composites also showed a similar behavior with the highest MEVC value of ~14 mV/cm Oe at low frequencies and ~200 mV/cm Oe at EMR. All the bilayers showed ME coupling for zero magnetic bias due to the magnetocrystalline anisotropy field in the ferrite that provided a built-in bias field. Full article

This study signifies the development and characterization of a composite material with a metallic matrix of aluminum reinforced with a steel mesh, utilizing centrifugal casting technology. An evaluation was conducted to ascertain the influence of the formulation process and the presence of the insert on the mechanical behavior with regard to tensile strength. The aluminum matrix was obtained from commercial and scrap alloys, elaborated by advanced methods of degassing and chemical modification. Meanwhile, the steel mesh reinforcement was cleaned, copper plated, and preheated to optimize wetting and, consequently, adhesion. The structural characterization was performed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy analyses (EDX), which highlighted a well-defined interface and uniform copper distribution. The composite was produced by means of horizontal-axis centrifugal casting in a fiberglass mold, followed by cold rolling to obtain flat specimens. A total of eight tensile specimens were examined, with measured ultimate tensile strengths ranging from 78.5 to 119.8 (MPa). A thorough examination of the fractured specimens revealed a brittle fracture mechanism, devoid of substantial plastic deformation. The onset of failures was frequently observed at the interface between the aluminum matrix and the steel mesh. The use of SEM and EDX investigations led to the confirmation of the uniformity of the copper coating and the absence of significant porosity or interfacial defects. A bimodal distribution of tensile strength values was observed, a phenomenon that is likely attributable to variations in mesh positioning and local differences in solidification. A correlation was established between the experimental results and an analytical polynomial model, thereby confirming a reasonable fit. In sum, the present study provides a substantial foundation for the development of metal matrix composites with enhanced performance, specifically designed for challenging structural applications. This method also demonstrates potential for recycling aluminum scrap into high-performance composites with controlled microstructure and mechanical integrity. Full article

Electrodeposited composite coatings are widely studied for their potential to improve surface properties such as wear resistance and friction reduction. This study investigates the effect of electrodeposition parameters on the structure, morphology, and tribological performance of three coatings: pure nickel (Ni), Ni–graphite (Ni-G), and Ni–MoS₂ (Ni-MoS₂). Three deposition conditions were selected based on a review of key electrochemical parameters commonly used in the literature. The coatings were analyzed in terms of morphological characteristics, friction and wear resistance. The findings reveal that higher current densities led to increased friction and wear in Ni coatings, while lower pH values promoted finer crystallite sizes and improved tribological behavior. Ni-G coatings exhibited larger cluster formations with reduced friction and wear, especially at low pH, whereas Ni-MoS₂ coatings developed a stable cauliflower-like morphology at pH 2, but showed reduced adhesion and structural integrity at higher pH levels. Scratch resistance tests performed under optimal deposition conditions showed that Ni-G coatings provided the highest resistance to mechanical damage, while Ni-MoS₂ coatings were more susceptible to microcracking and adhesion failure. These results underscore the importance of optimizing deposition parameters to tailor the microstructure and functional properties of composite coatings for enhanced tribological and mechanical performance. Full article

Drop-on-demand (DoD) printing is an additive manufacturing technique that utilizes functional inks containing nanoparticles (NPs) to fabricate electronic circuits or devices on a variety of substrates. One of the most promising applications for such technology is the aerospace industry, due to the capability of this method to fabricate custom low-weight geometric films. This work evaluates the performance of a gold (Au) nanoparticle (NP)-based film printed on a ceramic substrate for avionics applications, following the environmental temperature guidance of the Radio Technical Commission for Aeronautics (RTCA) DO-160. Experimental results show that the Au films, printed on alumina substrates, successfully survived the environmental temperature procedures for airborne equipment. The thermal coefficient of resistance (TCR) of the films was measured to be $2.7\times {10}^{-3} {°\mathrm{C}}^{-1}.$ Full article

This comprehensive review focuses on the most recent advances in electron backscatter diffraction (EBSD) methods in the context of materials science and includes a thorough evaluation of the sample preparation procedures unique to EBSD as well as a complete examination of the important operational parameters inherent in EBSD setups. This review highlights the importance of customizing EBSD parameters for precise microstructural imaging and enhancing understanding of material behavior. While some studies have explored grain boundary characterization, stored energy, and crystallographic orientation using EBSD, there is a clear need for more comprehensive investigations to fully leverage its capabilities. Additionally, there is a significant gap in understanding the optimal choice of the reference plane in EBSD analysis, indicating the necessity for further research to improve EBSD analyses’ accuracy and efficacy. The review seeks to present a detailed and contemporary viewpoint on the many applications, sample preparation techniques, and optimal operational considerations that jointly increase the adaptability and efficacy of EBSD in materials science research by relying on the relevant literature. Full article

As an important neurotransmitter, the concentration of dopamine (DA) reflects certain physiological conditions and DA-related diseases. Rapid monitoring of DA levels is of great significance in regulating body health. However, regular electrochemical DA sensors suffer from poor sensitivity, low selectivity and interference immunity, as well as a complex preparation process. Herein, we developed an accessible and cost-effective electrochemical sensor with a copper indium selenide (CuInSe2 or CIS)-modified screen-printed carbon electrode for DA discrimination. This DA sensor was developed using a facile one-step hydrothermal method without high-temperature quenching. Benefitting from the inherent merits of CIS and the conversion of Cu²⁺ and Cu⁺ during the catalytic reaction, the sensor attained both excellent sensitivity (2.511 μA·µM⁻¹·cm⁻¹) and selectivity among multiple substances interfering with DA. This work demonstrates the potential to improve the analytical performance of traditional electrochemical sensors. Full article

Ceramic–nano-metallic composite coatings of Al₂O₃–nano-Ni on an aluminum substrate (Al6061) were obtained using electrophoretic deposition (EPD). Three composite coatings with different ratios of nano-Ni, i.e., 25, 50, and 75%, were obtained. The phase composition of the resulting composite coatings was examined using XRD; this confirmed the existence of alumina and nickel in the composite coatings. The surface morphology and microstructure of the composite coatings were analyzed with SEM, while the chemical composition and phase content were determined through energy-dispersive spectroscopy. The hardness indenter results revealed a high hardness 420 HV for the Ni 25% composite coating However the hardness decreased with an increase in the Ni nanoparticle ratio, reaching a value of 360 HV for the Ni 75% composite coating. Reflectance measurements were conducted using a UV–visible spectrophotometer equipped with an integrating sphere (UV2600), and the composite coating with a Ni ratio of 75% exhibited the lowest reflectance of UV–visible light at <0.035. These results are promising for subsequent investigations into the absorbance of Al₂O₃–nano-Ni composite coatings within the sunlight irradiation wavelength range. Full article

Nature has created a unique combination of materials, and the design and material compositions used in nature are not successfully employed for industrial applications. Metallic multimaterials (MMMs) are a unique class of materials that combine the properties of various metallic constituents (both matrix and reinforcement(s)) to improve the functionality, performance in real-time, and application spectrum. Accordingly, this study explores the fabrication perspective of MMMs by combining both additive manufacturing (AM) and powder metallurgical (PM) routes. Ti6Al4V structures were fabricated via the laser powder-bed fusion (LPBF) process, and the reinforcement powders were added into the spark plasma sintering (SPS) mold where the Ti6Al4V structures were placed. Different reinforcement compositions including Mg, Al, Fe, Ni, and Cu were explored. Since the present study is focused on the variation of hardness, the hardness profile of the MMM composite was explored showing a sinusoidal trend. This study stands as a testimonial of fabricating MMM composites via a combination of AM and PM processes. Full article

Fe-Co alloy has the highest saturation magnetic flux density among soft magnetic materials, and Fe₅₀Co₅₀ has the maximum permeability of Fe-Co alloys. However, Fe-Co alloy is difficult to use in applications due to its brittleness. Various attempts have been made to improve its mechanical properties for applications, but its magnetic properties have not been retained. This research focuses on improving the magnetic properties of Fe-Co electrical steels at various heat treatment temperatures with the addition of 2 at.% vanadium. To reveal the ordered body-centered cubic phase, which has good soft magnetic properties, the thermal properties of the steels were investigated with differential scanning calorimetry. The microstructure of the electrical steels after heat treatment was analyzed by scanning electron microscopy, and the tendencies of their magnetic properties, measured by a DC B-H loop tracer and a vibrating sample magnetometer, were explored in connection with the microstructure. The decrease in coercivity up to 800 °C was due to stress relief and grain growth, and its increase at 850 °C is believed to be due to the pinning effect of the V-rich phase in the grain boundary. The optimal heat treatment temperature was found to be 800 °C because the steel had reasonable magnetic saturation (2.28 T) and hysteresis loss (0.47 W/kg), the highest magnetic flux density at 5000 A/m, and the lowest coercivity (56.7 A/m). Full article

The choice of efficient methods for the immobilization of high-level waste (HLW) resulting from the reprocessing of spent nuclear fuel (SNF) is an important scientific and practical task. The current policy of managing HLW within a closed nuclear fuel cycle envisages its vitrification into borosilicate (B-Si) or alumina–phosphate (Al-P) glasses. These wasteforms have rather limited waste loading and can potentially impair their retaining properties on devitrification. The optimal solution for HLW immobilization could be separating radionuclides into groups using dedicated capacious durable matrices. The phases of the Nd₂O₃–ZrO₂–TiO₂ system in this respect are promising hosts for the REE (rare earth elements: Nd, Ce, La, Pr, Sm, Gd, Y) –MA (MA: Am, Cm) fraction of HLW. In this manuscript, we present data on the composition of the samples analyzed, their durability in hot water, their behavior under irradiation, and their industrial manufacturing methods. Full article

This research examined the biochemical and microbiological characteristics of linen–copper (LI-Cu) composite materials, which were synthesized using magnetronsputtering techniques. The LI-Cu composites underwent comprehensive physicochemical and biological analyses. Physicochemical evaluations included elemental analysis (C, O, Cu), microscopic examination, and assessments of surface properties such as specific surface area and total pore volume. Biological evaluations encompassed microbiological tests and biochemical–hematological assessments, including the activated partial thromboplastin time (aPTT) and prothrombin time (PT). We determined the effect of LI-Cu materials on the viability and DNA damage in peripheral blood mononuclear (PBM) cells. Moreover, we studied the interactions of LI-Cu materials with plasmid DNA using a plasmid relaxation assay. The antimicrobial activity of LI-Cu composites was assessed using methodologies consistent with the EN ISO 20645:2006 and EN 14119:2005 standards. Specimens of the tested material were placed on inoculated agar plates containing representative microorganisms, and the extent of growth inhibition zones was measured. The results demonstrated that the modified materials exhibited antimicrobial activity against representative strains of Gram-positive and Gram-negative bacteria, as well as fungi. The results showed the cyto- and genotoxic properties of LI-Cu against PBM cells in a time- and power-dependent manner. Furthermore, the LI-Cu composite exhibited the potential for direct interaction with plasmid DNA. Full article

To achieve carbon neutrality, a reduction in car body weight is essential. Multi-material structures that use lightweight materials such as carbon fiber-reinforced polymers (CFRP) and aluminum (Al) alloy are used to replace parts of steel components. This multi-material method requires specific joining techniques for bonding dissimilar materials. Friction stir spot welding (FSSW) is one of the joining techniques used for joining dissimilar materials, enabling rapid and strong joints. FSSW for bonding A5052 Al alloy and carbon fiber-reinforced thermosetting resin (CFRTS) utilizing composite laminates with integrally molded thermoplastic resin in the outermost layer has been developed. However, joints using this method cause pyrolysis due to excessive frictional heating at the tool’s bottom, which may affect joint strength and promote corrosion in Al alloy. Therefore, this study developed new tools, a concave-shaped tool without a probe, a concave-shaped tool with a probe and a conventional FSSW tool, and investigated the influence of heat distribution and joint strength using the three new tools. The newly developed concave-shaped tool with a probe suppressed 7% of maximum heat input, decreased the pyrolysis area of epoxy resin by 47%, and increased joint strength by 4%. Finite element analysis also showed the suppression of heat input through the newly developed concave-shaped tool with a probe, achieved by reducing the contact area between the tool and Al alloy. Full article

This study investigates the effects of magnesium (Mg) content, silicon carbide (SiC) reinforcement, and aging temperature (AT) on the ultimate tensile strength (UTS) and Brinell hardness number (BHN) of eutectic Al-Si composites using a full factorial experimental approach. The analysis reveals that increasing Mg content from 0 wt% to 1.5 wt% significantly enhances UTS, likely due to solid solution strengthening and improved particle reinforcement. Similarly, a rise in SiC content up to 4 wt% leads to a notable increase in UTS, indicating effective matrix reinforcement. AT is crucial, with the highest UTS achieved at 100 °C; however, overaging at 200 °C results in reduced strength due to precipitate coarsening. Interaction plots demonstrate a synergistic effect between Mg and SiC, where higher levels of both contribute to a more substantial increase in UTS. The results also show that while both Mg and SiC improve UTS, their effects are optimized with appropriate aging conditions, although overaging diminishes these benefits. Analysis of variance (ANOVA) highlights that AT, Mg, and SiC each significantly impact UTS and BHN, with SiC having the greatest effect of 47.92% on hardness and AT having the greatest effect of 36.58% on the UTS. The interaction between SiC particles and AT is particularly influential on BHN. These findings emphasize the importance of carefully optimizing processing conditions to enhance the mechanical properties of eutectic Al-Si composites. Full article