Mohammad Salavati

Plasma electrolytic oxidation (PEO), applied to light metals such as titanium, aluminum, and magnesium, creates a two-layer coating and has become increasingly important in metal coatings. However, due to the high voltage and temperature of the process, no online instrument could monitor the underlying mechanism. This paper presents a new image proving that the surface of PEO-coated Mg3ZnCa boiled during the process and argues that three hypotheses are involved in the PEO mechanism based on boiling caused by tolerating high voltage during the PEO process, which could explain the current‒voltage diagram of the process. Finally, nanoindentation was used to measure the elastic module and hardness of the PEO layers. The nanoindentation test results revealed the similarity of the elastic module of the outer porous layer and the primary alloy, with values of 40.25 GPa and 41.47 GPa, respectively, confirming that the outer porous layer corresponds to the cold plasma-gas phase formed during the PEO process.

Improving the ductile deformation behavior of Mg-SiC nanocomposites without compromising strength is critical to enhancing their mechanical properties. Mg-SiC nanocomposites are produced through mechanical milling, cold isostatic pressing, sintering, and hot extrusion processes. This study investigates the uniaxial stress–strain response and deformation behavior of the Mg-SiC nanocomposite compared to pure Mg samples with and without the milling process. The deformation behavior was investigated by two-dimensional (2D) digital image correlation (DIC) at two macroscopic and microscopic scales, employing light micrographs and in situ loading samples, respectively, in the scanning electron microscope. Compared to the pure Mg samples, the mechanical test results demonstrated a significant improvement in strength (80 MPa) and fracture strain (23.5%) of the Mg-SiC nanocomposite. The three-dimensional (3D) representative volume element (RVE) model revealed the particle dispersion effect on the mechanical properties of the nanocomposite. The RVE results demonstrate ductile deformation behavior in the sample with homogenous dispersion of SiC particles compared with the heterogeneous dispersion of SiC particles in Mg-SiC nanocomposite. The results demonstrated a good agreement between DIC and RVE predictions for Mg-SiC nanocomposites across macro- and microscales.

This study investigates the mechanical properties of α-chitin and chitosan biocomposites using molecular dynamics (MD) and stress–strain analyses under uniaxial tensile loading in an aqueous environment. Our models, validated against experimental data, show that α-chitin has a higher directional elastic modulus of 51.76 GPa in the x and 39.76 GPa in the y directions compared to its chitosan biocomposite, with 31.66 GPa and 26.00 GPa in the same directions, demonstrating distinct mechanical behaviors between α-chitin and the biocomposite. The greater mechanical stiffness of α-chitin can be attributed to its highly crystalline molecular structure, offering potential advantages for applications requiring load-bearing capabilities. These findings offer valuable insights for optimizing these materials for specialized applications.

The mechanical properties of α-chitin and chitosan biocomposite are investigated due to their broad range of potential applications in bioengineering, materials science, and environmental technology. Employing molecular dynamics (MD), and stress-strain analyses, this study comprehensively investigates biopolymers mechanical response and anisotropic mechanical behavior under uniaxial tensile loading conditions in an aqueous environment. Our computational models were validated against existing experimental data, showing high degrees of correspondence. Uniaxial tensile tests revealed that α-chitin exhibits a remarkable ultimate tensile strength (UTS) of 10.07 GPa in the crystalline chain direction (y-axis) at a high strain rate of 0.636, compared to a significantly lower UTS of 2.78 GPa in the perpendicular direction (x-axis) at a lower strain rate of 0.066. The biocomposite nanostructure, encompassing randomly distributed chitosan, reduced stiffness, maintaining remarkable flexibility as α-chitin, with a UTS of 5.03 GPa in the y-axis and 2.34 GPa in the x-axis. Further, the directional elastic modules for α-chitin were calculated as 51.76 GPa and 39.76 GPa in the x and y directions, respectively. In contrast, these values for the α-chitin-chitosan biocomposite were estimated as 31.66 GPa and 26.00 GPa, respectively. The findings provide valuable insights into the distinct mechanical properties of α-chitin and chitosan biocomposite, making a substantial contribution to optimizing these materials for specialized applications.

Achieving uniformly distributed reinforcement particles in a dense matrix is crucial for enhancing the mechanical properties of nanocomposites. This study focuses on fabricating Mg-SiC nanocomposites with a high-volume fraction of SiC particles (10 vol.%) using cold isostatic pressing (CIP). The objective is to obtain a fully dense material with a uniform dispersion of nanoparticles. The SiC particle size impact on the compressibility and density distribution of milled Mg-SiC nanocomposites is studied through the elastoplastic Modified Drucker-Prager Cap (MDPC) model and finite element method (FEM) simulations. The findings demonstrate significant variations in the size and dispersion of SiC particles within the Mg matrix. Specifically, the Mg-SiC nanocomposite with 10% submicron-scale SiC content (M10Sµ) exhibits superior compressibility, higher relative density, increased element volume (EVOL), and more consistent density distribution compared to the composite containing 10% nanoscale SiC (M10Sn) following CIP simulation. Under 700 MPa, M10Sµ shows improvements in both computational and experimental results for volume reduction percentage, 2.31% and 2.81%, respectively, and relative density, 4.14% and 3.73%, respectively, compared to M10Sn. The relative density and volume reduction outcomes are in qualitative alignment with experimental findings, emphasizing the significance of particle size in optimizing nanocomposite characteristics.

In this paper, we present a deep energy method for functionally graded beams based on both Euler–Bernoulli and Timoshenko beam theory to study their mechanical and thermal properties. We consider the effect of temperature as well as porosity under saturated and unsaturated conditions. The objective function is related to the total potential energy (and boundary conditions) and minimized through neural network training. The results are validated by comparison with benchmark problems available in the literature.

The efficient performance of metal-ion batteries strongly depends on electrode materials characteristics. Two-dimensional (2D) materials are among promising electrode materials for metal-ion battery cells, owing to their excellent structural and electronic properties. Two-dimensional graphdiyne has been recently fabricated and revealed unique storage capacities and fast charging rates. The current study explores the performance of the novel phosphorated-triphenylene graphdiyne (P-TpG) monolayer as an anode material for Li-, Na-, K-, Mg-, and Ca-ions storage via extensive density functional theory (DFT) simulations. Our results reveal that the stable structure of P-TpG monolayers delivers ultra-high storage capacities of ~2148, ~1696, ~1017, and ~2035 mA·h·g⁻¹ for Li-, Na-, K-, and Ca- ions, respectively. Notably, the metallic electronic behavior is illustrated by adsorbing metal-ions on the P-TpG nanosheets, suggesting a good electronic conductivity. The NEB results demonstrate that P-TpG can serve as an outstanding candidate for the optimal charging/discharging process. This theoretical study suggests P-TpG nanosheets as a highly promising candidate for the design of advanced metal-ion batteries with remarkable charge capacities and optimal charging/discharging rates.