Gajanan M Naik, Santhosh Kumar B M, Shivakumar M M, Ramesh S, Maruthi Prashanth B H, Gajanan Anne6,
Volume 22, Issue 3 (9-2025)
Abstract
Magnesium and the alloys made from the same metal are utilized in the engineering applications such as automotive, marine, and aircraft, among others due to high strength to weight. Nevertheless, the applications of magnesium alloys are currently limited to a certain level due to their poor wear and corrosion properties. Another effective strategy for enhancing these properties involves utilizing the process of equal channel angular extrusion (ECAE), which serves to refine the grain structure, thereby resulting in improved material properties. This paper aims to establish the relationship between grain size reduction and wear and corrosion of AZ91 alloy. The wear performances of both coarse-grained and fine-grain alloy were conducted using L9 orthogonal array of experiments in order to study the effects of control parameters on wear performance. In the study, it has also been identified that through ECAP, the corrosion barrier and wear characteristics of the alloy were enhanced due to fine-grain-structure and the spheroidal precipitation of the second β-phase particles. Further, the influence of these changes on the performance of the AZ91 Mg alloy was assessed using SEM.
Farzaneh Sadat Teimoory Toufal, Alma Kalali, Arvin Attari Navab, Mohadeseh Reyhani, Hamidreza Rezaie, Jafar Javadpour,
Volume 22, Issue 3 (9-2025)
Abstract
Glass ionomer cements (GICs) are widely utilized in clinical restorative dental applications, which suffer from poor mechanical strength. Recent research shows that GIC achieves optimal performance when modified with lower percentage of filler materials, particularly when using nanoparticles, due to the resultant increase in surface area and packing density of the cement. Notably, while some modifications show promise, others fail to deliver improvements in material characteristics. This study addressed a gap in the literature by investigating the impact of acidic/basic additives, such as Diopside (CaMgSi2O6) and Zirconia (ZrO2), on the properties of the cement. The reactivity of zirconia and Diopside differ distinctly from traditional calcium-aluminosilicate glass when exposed to acidic conditions in GICs. Also, to clarify the impact of acidity/basicity on filler reactivity during cement setting, the potential mechanical enhancement effects by using nano-sized particles is limited to submicrons. This research incorporated Diopside at concentrations of 2, 4, and 6 wt.%, and zirconia at 8, 10, and 12 wt.% into a glass powder component. Results demonstrated that adding 8 wt.% Zirconia led to a 49% enhancement in compressive strength, also improve microhardness by 16 wt.%, attributed to its non-reactive nature, minimal dissolution, and high inherent strength of ZrO2. In contrast, Diopside had a detrimental effect due to its basic nature compared to that of glass powder. These findings highlight the potential of zirconia as a valuable reinforcing material for the successful mechanical performance of glass ionomer cements. Conversely, basic fillers like diopside appear unsuitable for achieving improved mechanical performance in these systems.
Asiehsadat Kazemi, Fatemeh Bahar Azodzadegan, Seyed Mohamad Amin Tabatabee,
Volume 22, Issue 3 (9-2025)
Abstract
Fluorinated graphene is an up-rising member of the graphene family and attracts significant attention since it is a 2D layer-structure, is self-lubricating, has wide bandgap and high thermal and chemical stability. By adjusting the C–F bonding character and F/C ratios through controlled fluorination processes, fluorinated graphene can be utilized for a wide range of applications including energy conversion, storage devices, bio- and electrochemical sensors. Herein, monolayer CVD graphene/Cu was fluorinated via SF6 plasma with time and power sequence trial. Structural, morphological, roughness, adhesive forces, and wettability of fluorinated graphene was explored. Insight was gained by Raman spectroscopy, SEM and EDS, surface roughness and adhesive force measurements via AFM on different samples. Fluorination produced p-doped structure, blue shift in the 2D peak and red shift in D peak of the Raman spectra of graphene. Increase in plasma time increased the defects and weakened C-C bonds much more rapidly at higher plasma power (40W) while lower plasma power (15W) retained more of graphene properties (having high La, LD and low nD) confirmed by Raman, SEM and EDS analyses. Surface roughness and adhesive forces on graphene surface were mostly increased with the increase in plasma time at a certain power. Higher plasma power resulted in more hydrophobic surfaces and even the wettability tuning occurred in the hydrophobic regime while lower plasma power demonstrated tuning in the hydrophilic regime. Influence of the underlying surface and π -electron pairs were shown to play more significant roles in tuning the wettability at higher plasma power.
Farhood Heydari, Seyed Mohammad Mirkazemi, Bijan Eftekhari Yekta, Seyyed Salman Seyyed Afghahi,
Volume 22, Issue 3 (9-2025)
Abstract
This study systematically investigates the crystallization behavior, phase evolution, and dielectric properties of a BaO-Al₂O₃-SiO₂ glass system modified with 10 wt% TiO₂. Thermal characterization revealed that TiO₂ addition notably reduced the glass transition temperature (from 781.6°C to 779.4°C) and softening point (from 838°C to 824.8°C) compared to the TiO₂-free glass, consequently decreasing the calculated nucleation temperature (from 810°C to 800°C). While differential thermal analysis indicated sluggish crystallization kinetics, isothermal heat treatments identified 1000°C as the optimal processing temperature, leading to the development of a multiphase crystalline assemblage that beneficially included the target monoclinic Ba3.75Al7.5Si8.5O32 phase, which was absent in the TiO₂-free glass. X-ray diffraction identified this phase, along with celsian (BaAl₂Si₂O8) polymorphs and barium titanate crystallites, as the dominant crystalline phases. SEM revealed anisotropic crystal growth (1.14-1.52 μm length). Dielectric characterization in the Ku-band (12.4-18 GHz) demonstrated significant property enhancements, with the relative permittivity decreasing from 10.40 to 6.38 and loss tangent improving from 0.3 to 0.2 after crystallization. These improvements, attributed to the specifically tailored crystalline phase assemblage facilitated by TiO₂, make this glass-ceramic system particularly suitable for advanced microwave applications requiring low dielectric loss and high-frequency stability. The effectiveness of TiO₂ as a crystallization modifier for achieving optimized dielectric properties through controlled devitrification and targeted phase formation is underscored.
Ali Azari Beni, Saeed Rastegari,
Volume 22, Issue 3 (9-2025)
Abstract
Aluminide coatings are widely used in high-temperature applications due to their excellent corrosion resistance and thermal stability. However, optimizing their composition and thickness is crucial for enhancing performance under varying operational conditions. This study investigates the optimization of aluminide coatings through a data-driven approach, aiming to predict the coating thickness based on various composition and process parameters. A comparative analysis of six machine learning models was conducted, with the k-nearest neighbors regressor (KNNR) demonstrating the highest predictive accuracy, yielding a coefficient of determination R² of 0.78, a root mean square error (RMSE) of 18.02 µm, and mean absolute error (MAE) of 14.42. The study incorporates SHAP (Shapley Additive Explanations) analysis to identify the most influential factors in coating thickness prediction. The results indicate that aluminum content (Al), ammonium chloride content (NH4Cl), and silicon content (Si) significantly impact the coating thickness, with higher Al and Si concentrations leading to thicker coatings. Zirconia (ZrO2) content was found to decrease thickness due to competitive reactions that hinder Al deposition. Furthermore, the level of activity in the aluminizing process plays a crucial role, with high-activity processes yielding thicker coatings due to faster Al diffusion. The pack cementation method, in particular, produced the thickest coatings, followed by gas-phase and out-of-pack methods. These findings emphasize the importance of optimizing composition and processing conditions to achieve durable, high-performance aluminide coatings for high-temperature applications.
Marzieh Akbari, Fatemeh Dabbagh Kashani, Seyed Mohammad Mirkazemi,
Volume 22, Issue 4 (12-2025)
Abstract
CIGS solar cells are currently very high-efficiency thin-film solar cells. With regard to higher efficiency in solar cells, research is being conducted on the influence of both light scattering and plasmonic resonances due to metallic nano-structures. This article discusses the assessment of the incorporate plasmonic nanostructures on the absorber layer of a 1000 nm CIGS solar cell, in terms of light absorption and device performance. It is noted that decisions on material, size, and surface coverage (Occupied Factor) were important considerations that affected the performance. Opto-electrical assessment was used to investigate absorption, charge-carrier generation, current density-voltage response, power-voltage properties, and total efficiency. Using simulations, we discovered the aluminum nanosphere arrays (200 nm diameter, Occupied Factor 0.64) at the top of the absorber layer yielded the maximum efficiency (26.14%). This was shown by the resonances, and near-field distribution garnered from the nanospheres boost charge carrier generation, diminished recombination losses, and increased charge separation. Collectively, these raised the performance of the CIGS solar cells in this research and suggested hope for moving CIGS and potentially other photovoltaics forward using nanoscale plasmonic resonances.
