Bulletin of Materials Science最新文献

This study presents an experimental and numerical investigation of the dynamic behaviour of sandwich plate consists of  jute fibre-reinforced face layers and TiO₂-incorporated tea waste epoxy core layers. The core layers are reinforced with varying amounts of weight percentages of TiO₂ nanofiller (0%, 1%, 1.5% and 2%) to assess their impact on the tensile strength and free vibration responses. Tensile properties are evaluated using uniaxial tensile tests according to the ASTM D 3039 standard. The natural frequencies of the sandwich plates are obtained experimentally through experimental modal analysis using a fast fourier transform (FFT) analyser with PULSE Lab software (Bruel & Kjaer). These experimental findings are validated against numerical results obtained from the finite element software ABAQUS, where material properties are derived from the tensile tests are used as inputs. Additionally, numerical simulations are conducted to explore the effects of varying boundary conditions, aspect ratios, core thicknesses, face l ayer thickness ratios, and ply orientations (symmetric and antisymmetric) on the dynamic behaviour of the sandwich plates. Comparison with published literature confirms the accuracy and reliability of the proposed sandwich structures. The results provide insights into optimizing the dynamic performance of jute fibre-reinforced composite structures with sustainable tea waste-based epoxy cores for lightweight engineering applications. The optimum performance was observed at 2 wt% TiO₂ loading, which showed the best compromise between improved tensile strength and enhanced vibration damping without agglomeration effects seen at higher concentrations.

The fused filament fabrication (FFF) is a widely used technique for 3D printing of thermoplastics. The mechanical properties of 3D-printed samples may decrease with an increase in operating temperature. In this study, the degradation of the mechanical properties of 3D-printed polyethylene terephthalate glycol samples has been studied using dynamic mechanical analysis. The effect of process parameters such as layer thickness and operating frequency has been analysed in detail. The storage and loss modulus at the glass transition temperature decrease with an increase in layer thickness. Temperature and frequency-dependent analytical models and machine-learning (ML) algorithms, such as K-nearest neighbours, random forest (RF) and gradient boosting, are used to estimate the modulus variation as a function of temperature and loading frequency. The predictability of analytical models and ML models has been assessed. The fitting coefficients of the analytical model are evaluated as a function of temperature and frequency. Also, it is observed that the RF algorithm predicts the dynamic mechanical behaviour of 3D-printed samples with better accuracy at known frequencies as well as at unknown frequencies. For a layer thickness of 0.17 mm at 1 Hz frequency (known frequency), the RF algorithm demonstrated better performance indices with the highest R²-value of 0.983 compared to other ML algorithms. Similarly, for a layer thickness of 0.17 mm at 9 Hz frequency (unknown frequency), the RF algorithm predicted the modulus values with the highest R²-value of 0.967 compared to other ML algorithms.

Shear thickening fluid (STF) is a novel nanosuspension, formed by the uniform dispersion of micro- and nano-silicon within a specific dispersant. This study presents a review of the research on the applications of STF in impact protection, with a focus on two forms: composite fabrics and sandwich panels. The first section presents an initial overview of the impact protection performance of various STF-treated fabrics made from different fibres. Subsequently, methods for optimizing performance and potential application directions for composite fabrics are analysed. For STF sandwich panels, the enhancement of impact resistance in protective structures due to STF is highlighted, along with an evaluation of its application prospects in protective gear, aerospace and other fields. Finally, this study outlines the potential problems and challenges that STF may encounter in impact protection applications, drawing on the current status and developmental trajectory of STF’s applications.

The present study uses electrochemical approaches, such as linear and cyclic polarization, to examine the effects of immersion time (7, 14, 21 and 28 days) on the corrosion behaviour of X70 and X80 line pipe steels in a simulated concrete pore solution (SCPS) contaminated with 3.5 wt% NaCl (pH ~ 12 to 13.8). The results show that the corrosion resistance of the X70 line pipe steel decreases from 7 to 21 days, and then increases significantly after 28 days. For the X80 line pipe steel, corrosion resistance improves from 7 to 14 days due to the preferential dissolution of the bainitic phase, which enables the building of a passive film. However, corrosion resistance declines after 21 days before improving again after 28 days. This occurrence can be ascribed to the formation of stable passive film on both the steels after extended immersion periods (beyond 28 days), driven by the elevated phase fraction of α/γ* in corrosion products, where α signifies the stable α-FeOOH phase and γ* encompasses the less stable phases, such as γ-FeOOH, β-FeOOH and Fe₃O₄.

In the current study, the polymer composites are prepared by blending varied percentages of high-density polyethylene (HDPE) and polycarbonate (PC) along with fixed amounts of coir fibre (reinforcement) and f-MWCNT (nanofiller) and then compressed into thin sheets. The influence of changing the HDPE/PC ratio with fixed levels of reinforcement and nanofiller on the mechanical and tribological properties has been looked into using tensilometer and pin-on-disc test setup, respectively. They were also characterized for density, hardness, surface roughness and functional group identification (Fourier transform infrared spectroscopy), respectively. It is observed that the composite with HDPE/PC matrix ratio of 70/19 with 10 wt% coir fibre and 1 wt% f-MWCNT yielded improved results in terms of higher strength (21.1%) and modulus (4.5%) as well as good slide wear resistance and low friction characteristics (0.14) as compared to other composites. The results obtained have been assessed with the fractured and wear damage morphology using scanning electron microscope. Thus the prepared composites could be a choice for manufacturing of tyres, bumpers and panels, etc. in automotive sectors, as it possesses appropriate degree of mechanical and tribological properties.

The present research work approaches the removal of fluoride from contaminated water using an eco-friendly novel iron-based polyaniline nano-composite (PAn) in a batch mode method. The fluoride adsorption efficiency was studied with variation of parameters like initial fluoride concentration 10-20 mg L⁻¹, contact time 10-90 min, variation of adsorbent dose 0.1−1 g, temperature 25°, 30° and 40°C, pH 2-12 and presence of competing ions at 25°, 30° and 40°C and was optimised with artificial neural network model (ANN). The experimented adsorption data was best fitted to Langmuir adsorption isotherm with maximum adsorption capacity of 89.41 mg g⁻¹ at 40°C. The adsorption kinetics followed the pseudo second order reaction. The thermodynamics studies indicate that the adsorption process was spontaneous and endothermic in nature. The maximum fluoride removal was found to be 91% with good agreement to the results predicted by ANN model (structure 5-10-1). The PAn nano-composite can be used maximum of up to four cycles for defluoridation of drinking water. To determine the adhesion of fluoride on the PAn nano composite, the material was characterized using different instrumental analyses like SEM EDS, BET, XRD and FTIR. The FePAn nanocomposite can be used maximum up to four cycles for defluoridation of drinking water.

Magnetodielectric composites _xPb_0.8Nd_0.2(Zr_0.52Ti_0.48)O₃-_1-xSrFe₁₂O₁₉ (x = 0.50, 0.52, 0.54, 0.56, 0.58) have been reported. Structural phase analysis confirmed successful synthesis of reported ceramic composites. Magnetic hysteresis reveals magnetic ordering in prepared composites whereas micrographs strongly support dielectric permittivity. All prepared composites exhibit high values of dielectric constant. Strong magnetodielectric response (MDR) is observed in low frequency region which goes on decreasing with frequency, indicating Maxwell-Wagner interfacial phenomenon in the studied composites. The MDR extends to higher frequency range (>100 kHz) signifying strain mediated mechanical coupling between ferrite and dielectric phases which is calculated in terms of the coupling coefficient (γ).

Temperature and pressure dependences of the soft-mode frequency ((omega)) and the dielectric constant ((varepsilon)) are studied for the tetragonal-cubic transition (T_C = 395 K) in BaTiO₃. We find that variations of the frequency and the dielectric constant with the temperature (pressure) are related to each other linearly close to the phase transition in this ferroelectric material. Instead of the Curie-Weiss behaviour of the dielectric constant, the critical behaviour of both soft-mode frequency and the dielectric constant is expressed by the power-law formulae, and the critical exponents are determined using the observed data from the literature. Our predicted frequencies of the soft mode at various pressures and temperatures, can be examined by the experimental measurements close to the tetragonal-cubic transition in BaTiO₃.

Cu–Ni–W thin films were deposited by varying the current density from –5 to –60 mA cm^–2 using the galvanostatic chronopotentiogram method on indium tin oxide (ITO) coated glass substrates. X-ray diffraction analysis revealed that Cu–Ni–W thin films exhibited face-centered cubic structures with the presence of specific crystallographic planes, particularly (111), (200) and (220) at 2θ values of 43.4°, 50.7° and 74.7°, respectively. The additional peaks observed at other 2θ values correspond to the NiW and Ni₄W phases. The scanning electron microscopy micrographs of the films demonstrated a uniform structure characterized by a compact and dense morphology. The surface of the films displayed a metallic lustre attributed to the presence of Cu, Ni and W. The cross-sectional micrographs of the films indicated an average thickness of 1.1 to 1.2 µm. The energy dispersive X-ray spectroscopy analysis have shown that an increase in deposition current density leads to a rise in the relative concentration of Ni and W within the films, whereas the concentration of Cu decreased. The XPS survey spectrum also confirmed the presence of metallic Cu, Ni and W in the deposits. It was found that film deposited at higher current densities favours the growth of a smaller crystalline size of 17 nm and a higher degree of texture coefficient of 2.48. The maximum micro-strain of approximately 16% was calculated from the peak broadening of the X-ray diffractograms. The strong (111) texture and nano-crystallites as confirmed by XRD, resulted in an outstanding corrosion resistance of 16.22 kΩ-cm² for the film deposited at –60 mA cm^–2.