Advanced Models for Modulus and Strength of Carbon-Nanotube-Filled Polymer Systems Assuming the Networks of Carbon Nanotubes and Interphase Section

This study focuses on the simultaneous stiffening and percolating characteristics of the interphase section in polymer carbon nanotubes (CNTs) systems (PCNTs) using two advanced models of tensile modulus and strength. The interphase, as a third part around the nanoparticles, influences the mechanical features of such systems. The forecasts agree well with the tentative results, thus validating the advanced models. A CNT radius of >40 nm and CNT length of <5 μm marginally improve the modulus by 70%, while the highest modulus development of 350% is achieved with the thinnest nanoparticles. Furthermore, the highest improvement in nanocomposite’s strength (350%) is achieved with the CNT length of 12 μm and interfacial shear strength of 8 MPa. Generally, the highest ranges of the CNT length, interphase thickness, interphase modulus and interfacial shear strength lead to the most desirable mechanical features

Application of Image Processing to Predict Compressive Behavior of Aluminum Foam

An image processing technique was used to model the internal structure of aluminum foam in finite element analysis in order to predict the compressive behavior of the material. Finite element analysis and experimental tests were performed on aluminum foam with densities of 0.2, 0.25, and 0.3 g/cm3. It was found that although the compressive strength predicted from the finite element analysis was higher than that determined experimentally, the predicted compressive stress-strain curves exhibited a tendency similar to those determined from experiments for both densities. However, the behavior of the predicted compressive stress-strain curves was different from the experimental one as the applied strain increased. The difference between predicted and experimental stress-strain curves in a high strain range was due to contact between broken aluminum foam walls by the large deformation

Effect of nano-phased bismuth–tin alloy surface coating on tribo-mechanical properties of basalt fiber reinforced composites

A novel method for coating basalt fiber with a eutectic bismuth–tin (Bi–Sn) mixture was developed. Bi-Sn nanoparticles were synthesized using a sol-gel process and deposited on basalt fiber by chemical vapor deposition, with the aim of evaluating the tribo-mechanical properties of the final epoxy-composite material. X-ray diffraction showed that the synthesized Bi–Sn alloy was highly polycrystalline with equal distribution of tetragonal and orthorhombic Bi–Sn polymorph phases with crystallite sizes between 17 and 55 nm. High-resolution electron microscopy revealed that the sample possesses highly fused, flake-stacked planar layers, with 50 nm-thick flakes of variable length. Elemental analysis determined that the alloy contains 57% Bi (at.wt%), and Raman spectroscopy confirmed the characteristic Bi–Sn fingerprint peaks of 148, 201, and 397 cm−1. Thermal analysis of the composites showed good thermal stability with only 4% mass loss at 700 °C. Furthermore, an increase in the Bi–Sn loading enhanced the tribo-tensile properties. It was found that at a Bi-Sn gravimetric loading of 0.2 g the composite yielded the highest ultimate tensile strength of 303 MPa compared to the reference (154 MPa), even as the Young's moduli showed a decrease in elasticity by up to 24.99%. Moreover, the tribology results showed a good friction coefficient (0.5), with a negligible wear rate (4.53 × 10−8 mm3/Nm) and relatively low wear volume (0.118 mm3). Thus, the proposed method resulted in alloy composites with improved tribo-mechanical properties, and has potential applicability in the development of lead-free solders

Synthesis, characterization, and feasibility investigation of dysprosium-doped samarium iron oxide nano-powder/polydimethylsiloxane (Dy-SmFeO/PDMS) nano-composite for dynamic magneto-mechanical stability

In this study, the synthesis and characterization of a dysprosium-doped samarium iron oxide nano powder/polydimethylsiloxane (Dy-SmFeO/PDMS) nano-composite are described. The sol-gel citrate method was employed for the synthesis, yielding highly polycrystalline nano powders with a polymorphic distribution, as revealed by X-ray diffraction and Rietveld analysis. Raman spectroscopy was utilized to investigate the chemistry of the nano powders. Notably, the readings obtained using a vibrating sample magnetometer highlighted the intriguing ferromagnetic-to-antiferromagnetic coupling behavior of the samples. The field-emission scanning electron microscopy analysis indicated that the orthorhombic crystal surfaces were uniformly encapsulated by PDMS. Furthermore, a dynamic mechanical analysis was conducted under the influence of a magnetic field (1000 mT) revealed the excellent mechanical stability of the composite. This research highlights the potential of the Dy-SmFeO/PDMS composite as a promising magnetic material with desirable properties, opening up possibilities for various applications in fields such as micro-magnetic devices, sensors, spin valves, and actuators

Sol–gel combustion derived novel ternary transition metal boride-anisotropic magnetic powders and their magnetic property

We investigated the auto-ignition based sol–gel approach for the synthesis of ternary transition metal boride (TTMB) powders and studied their magnetic property. The obtained TTMB powders were found to have different crystallinity and magnetic behavior, based on the boron to metal ratio and further introduction of dysprosium into one of the sample lattice. The magnetic results obtained by vibrating sample magnetometer shows that TTMB is a soft magnet which demonstrates high ferromagnetic behavior with increased magnetic saturation based on the boron content, while the dysprosium based TTMB on contrary was found to exhibit an antiferromagnetic behavior. The TTMB powder showed no impurities as observed in Raman spectroscopy. The morphology of the powders obtained microscopically displays distinctive facets in the crystalline samples. The TTMB powders can be prospectively used in different polymer matrix to fabricate novel devices for sensors, environmental catalysts, radiation shielding and contrasting agents etc., to name a few

Electrochemical study of corrosion behavior of graphene coatings on copper and aluminum in a chloride solution

Electrochemical characteristics and corrosion behavior of graphene coatings on Cu and Al in a 0.1 M NaCl solution were investigated. The graphene coatings were deposited on a Cu surface by chemical vapor deposition. Multiple graphene layers were then mechanically transferred from the growth substrate, Cu, onto Al surface by a transfer technique. The corrosion stability of graphene coatings was determined by electrochemical impedance spectroscopy and open circuit potential, while the corrosion rate was evaluated using potentiodynamic sweep measurements. Surface morphologies of the graphene coatings were analyzed by scanning electron microscopy and energy dispersive spectroscopy. Obtained results indicate that Cu coated with graphene grown using chemical vapor deposition shows corrosion-inhibiting properties in 0.1 M NaCl. On the other hand, Al coated with a multilayer graphene film mechanically transferred from the Cu surface exhibits electrochemical characteristics similar to an Al oxide on bare Al. Better protective properties of graphene coating on Cu compared to the graphene coating on Al were observed, probably due to the breakage of Al oxide film, causing the corrosion of Al to proceed rapidly in the presence of chloride electrolyte