Iranian Journal of Materials Science and Engineering

Nanoreactor-Enabled Formation of Graphitic Film from a Non-Graphitizing Precursor at Low-Temperature

Aliyeh Afzalalghom

Gas-phase methods for graphite/graphene production, such as chemical vapor deposition (CVD), yield high-quality products but demand catalysts, substrates, high-purity hydrocarbon gases, specialized furnaces, and temperatures exceeding 1000 °C. Here, we demonstrate the synthesis of highly graphitized films with crystalline domains via low-temperature carbonization (900 °C) of nanoporous polydivinylbenzene (PDVB) microspheres, without reliance on a CVD system or catalysts. The films formed on the inner surface of the furnace quartz tube and were characterized by Raman spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM). Raman spectrum revealed a high graphitization degree (I_D1/I_G = 0.78), surpassing reported values for catalyst-free plasma- or low-pressure-assisted CVD. XRD showed a sharp diffraction peak at 2θ = 26.37° (d = 3.37 Å), exactly matching the (002) plane of Graphite-2H, while HRTEM and selected area electron diffraction confirmed crystalline domains with p63/mmc symmetry. We propose that the intricate network of nanopores as nanoreactors in PDVB microspheres enables the generation and controlled release of fused benzene rings into the quartz tube, where they condense to form crystalline films. This approach reveals how a nanoscale confinement can be translated into a macroscopic, scalable route, offering a low-cost and facile method for graphite or graphene production.

The Synergistic Effect of Molybdenum Dopant Content and Pressure on the Optoelectronic and Mechanical Performance of CeO2: DFT+U Study

Hussein Miran

This contribution investigates the structural, opto-electronic, and mechanical properties of cerium oxide (CeO₂) and molybdenum-included cerium oxide (Ce_1-xMo_xO₂) under hydrostatic pressures of 0, 25, 50, 75, and 100 GPa. The computed results were executed by the state of the art density functional theory (DFT+U). The generalized gradient approximation (GGA) supported by the PBE functional has been utilized. Initially, the lattice dimensions of the cubic CeO₂ phase accounts to 5.438 Å. The electronic characteristics have inspected by assessing the band gap of the pure CeO₂ unit cell, which amounts to 3.134 eV. Incorporating Mo element into the host CeO₂ lattice declines the band gap to 2.045 eV of Ce_0.75Mo_0.25O₂. This value is more dropped when applying hydrostatic pressure till reaching 1.808 eV at 100 GPa. The projected density of states (PDOS) findings reveal a hybridization between CeO₂ and Mo with key contributions of Ce-4f, O-2p, and Mo-3d states. Furthermore, the assessed negative formation energy magnitudes of Ce_0.75Mo_0.25O₂under zero and applied hydrostatic stress evidence the thermodynamic stability, proposing the possible experimental fabrication of such system. Absorption curves examinations reveal a blue shift for the inspected structures. Under applied pressures, an enhancement in the absorption spectra has been observed by shifting toward the ultraviolet (UV) wavelength region, indicating the potential applications in optoelectronic devices.

Fabrication and Ablation Behavior of a Novel 3D Orthogonal Woven C/C-SiC-HfC Composite by I-CVI, SI, and LSI Combined Process

Amin Rezaei Chekani

A C/C-SiC-HfC composite was fabricated using a three-dimensional orthogonally woven (3DW) preform, and the effect of HfC ultra-high temperature ceramic (UHTC) particles on the microstructure and ablation properties of the composite was evaluated. First, pyrolytic carbon (PyC) was infiltrated into the 3DW preform by the I-CVI method. Then, impregnation of a suspension composed of HfC particles and phenolic resin into the 3DW preform. Next, liquid Si alloy was infiltrated into the C/C-HfC porous structure at 1650 °C to form a C/C composite with a SiC-HfC matrix. HfC particles and the continuous SiC phase among carbon fibers were saturated and during the oxyacetylene test, covered the surface of the C/C-SiC-HfC composite as a dense continuous SiO₂-HfO₂ layer. This layer acted as a barrier against the diffusion of oxygen into the bulk parts of the C/C-SiC-HfC composite. The results of the oxyacetylene flame test at 2500 °C for 120 s showed that the mass and linear ablation rates of the C/C-SiC composite were 4.8 mg/s and 3.75 µm/s, respectively. After the addition of HfC and the formation of the C/C-SiC-HfC composite, these rates decreased to 1.6 mg/s and 0.98 µm/s, respectively.

Catalytic Oxidation of Nitrite to Nitrate in Aquas Solution by Carbonate-Activated Charcoal

Sumrit Mopoung

Activated charcoals were prepared by activation with 600 W microwave irradiation in combination with pretreatments of tamarind wood derived charcoal in boiling mixtures with NaOH (1 g : 0 g - 1 g: 0.12 g). The samples were characterized by FTIR, XRD, SEM-EDS, and BET, and used for catalytic nitrite c oxidation under air atmosphere in the absence of light at 30°C, pH 6.5, and 120 rpm shanking for improved efficiency. The results show that the percent yields of tamarind wood derived activated charcoals (ACCs) were 88.51% - 94.66 %. The main carbonate compounds of ACCs are present in the materials after activation. Na⁺ ions and water molecules could be inserted into the graphitic layers during pretreatment and efficiently effected surface cracking of ACCs by 600 W microwave irradiation. The surface cracklings and porosities of ACCs increased with increasing concentration of NaOH from 1 M to 3 M with optimum at 2 M NaOH. The final products are mesopore materials containing macro and meso hole channels. It was found that the nitrite conversions exhibit high reaction rates and are completed within 20 min. The reactions proceed via catalytic oxidations and their rates increase with increasing concentrations of NaOH activation, while nitrite conversions via the disproportionation reaction wereinhibited.

Galvanostatic Deposition of Iron Powder from Sulfate Electrolytes: Experimental Analysis and Empirical Modeling

Daniela Grigorova

Producing high-purity iron powders with controlled particle morphology is essential for advanced powder metallurgy, additive manufacturing, and functional materials. However, achieving precise morphological control in environmentally benign, additive-free electrolytes remains challenging. This study systematically investigates the galvanostatic electrodeposition of iron powder from sulfate-based electrolytes containing 10.0 and 50.0 g·L⁻¹ Fe²⁺, focusing on the interplay between current density, pH evolution, deposition efficiency, and particle structure. A clear transition from compact, adherent deposits at low current densities to dendritic, easily detachable powders at higher values was observed. SEM analysis revealed well-defined dendritic aggregates at 7 A·dm⁻² (30–80 μm), whereas highly fragmented, porous agglomerates formed at 10 A·dm⁻², accompanied by fine-scale fragmentation driven by intense hydrogen evolution. XRD confirmed pure α-Fe for current densities up to 7 A·dm⁻², while partial oxidation to Fe₃O₄ occurred at 10 A·dm⁻²; EDX mapping further supported this surface oxidation. The deposited mass increased linearly with current density for both Fe²⁺ concentrations, with regression models yielding R² values above 0.96. Current efficiency decreased at high current densities due to enhanced parasitic reactions. Overall, the results demonstrate that galvanostatic electrodeposition in additive-free sulfate media enables controlled synthesis of iron powders, with tunable morphology and phase purity governed primarily by current density and electrolyte composition.

Preparation, Characterization and Antimicrobial Properties of Ag2O Nanoparticles Composited with Reduced Graphene Oxide

Layth Hayder Hameed kazem Al_Tmamimi

Researchers have increasingly investigated hybrid nanocomposites that mix physical and chemical properties of carbonaceous materials and metal/metal oxides. In this work, a nanocomposite composed of reduced graphene oxide and silver (I) oxide, rGO@Ag₂O, was prepared using ascorbic acid as a green reducing agent. The Ag₂O nanoparticles were synthesized by means of a controlled precipitation process in water. The carbonaceous material of rGO was obtained through a modified Hummers' approach. After being combined with a solvent, the Ag₂O and rGO in ethanol were dried with heat. The resultant nanocomposite was structurally and optically examined using different characterization techniques.
The results showed that GO has been successfully reduced, Ag₂O revealed a crystalline structure, and Ag₂O nanostructures were found on the surface of rGO sheets. Disk diffusion assay was adopted in order to evaluate antibacterial activity of nanocomposite against both Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) bacteria. The Ag₂O nanostructures in the composite form exhibited inhibition zone with higher diameter compared to their uncomposited counterparts. Higher antibacterial activity of rGO@Ag₂O was attributed to the role of negatively charged oxygen-containing groups present on the surface of rGO in slightly improvement in the stability of Ag₂O nanostructures.
Our findings show that rGO@Ag₂O could be a useful antimicrobial material for biomedical surfaces, as a coating, and in systems that clean water. It could be a good option for future research in nano-enabled antimicrobial technology because it can destroy bacteria, is made in an environmentally benign way, and could be made on a larger scale.

Influence of Process Parameters and Metallic Binders on Physicomechanical and Tribological Properties of WC-based Alloys Fabricated by the SPS

Ali Rasooli

There is a global need to develop engineering materials to address the increasing demands in various industries. Spark plasma sintering (SPS) is one of the most distinguished powder metallurgy techniques, offering the opportunity for the fabrication of different types of materials. This work emphasizes optimizations of the important process parameters, including temperature, pressure, and holding time, involved in the SPS of the WC, WC-Co, and WC-Cr, as well as assessing the influence of the content of the Co (6-24 wt.%) and Cr (0.2-1 wt.%) binders on the overall characteristics of the SPS-ed cermets. The results illustrate that the process parameters highly affect the physicomechanical properties of the SPS-ed WC, where the most appropriate conditions from a physicomechanical viewpoint are obtained at a sintering temperature of 1700 °C, a pressure of 80 MPa, and a holding time of 5 min. The included Co binder reduces the optimum temperature and pressure down to 1200 °C and 70 MPa, respectively. The addition of the Co improves the final properties of the WC irrespective of its content. The highest tribomechanical properties are attained when 18 wt. % of Co is added. Similar to that of Co, the incorporation of Cr into the WC increases the tribomechanical performance. In general, the use of Co and Cr metallic binders seems a useful strategy to promote the overall properties of the SPS-ed WC.

A Mathematical Model for Upper-Bound Analysis of Backward Extrusion in Ultra-Thin-Walled Tube Forming

RAMIN Ebrahimi

This study presents an analytical model based on the upper-bound method to investigate the backward extrusion of ultra-thin-walled tubes (wall thickness 100–400 µm). The deformation zone is divided into distinct regions with kinematically admissible velocity fields and defined discontinuities, allowing accurate estimation of strain rate field. The model incorporates effects of friction, wall thickness variation, and velocity discontinuities to predict extrusion force, deformation zone depth, and strain localization. Validation through both experimental measurements and finite element simulations demonstrates strong agreement with the analytical predictions. The proposed model offers an efficient and reliable framework for understanding deformation mechanics in precision tube extrusion and serves as a practical design tool in metal forming processes.

Experimental Investigation of Single Shot Peening on TiN Coated surfaces

Ehsan Bazzaz

Improvement of the mechanical properties of the coated surfaces was the matter of significant researches for a long time. A lot of physical and chemical operations were applied and examined on the coating surfaces successfully, but the effect of the mechanical treatments was not widely investigated. In this paper, the effect of a surface mechanical treatment on the micro coating layer has been studied and investigated. For this purpose, the necessary conditions have been created for implying impact to the coating surface. A setup of gas gun facility with well-designed and prepared projectiles are used to strike the sample surface with different speeds. A significant number of impacts have been inflicted on the test sample of the spade drill insert cutting tool. The consequence of this process is the change in crystal structure of the coating layer, which shows that under the created conditions, the crystal structure was not destroyed and instead getting compacted so that the size of the crystal grains has been reduced and considerably refined. Subsequent studies using electron microscopy have led to the measurement of the average size of the crystalline grains before and after impacts. Obviously, a significant effect has been observed and a meaningful trend has been seen for this change in the form of a linear relationship. The main result is that about 4% reduction in the average grain size happens when the impact speed changes by 10m/s. In this way, the principal basis for the use of this surface treatment in improving the surface properties of the micro coating layers is provided. This leads to the application of such treatments as an industry process for improvement of thin coating mechanical properties.

Design and Development of Fe₃O₄/ZnTiO₃/MWCNT/Epoxy Nanocomposite: An Integrated Experimental and Numerical Investigation of Microwave Impedance Matching and Scattering Parameters

Reza Sarkhosh

Today, the application of high‑performance thin‑film nanocomposites as impedance‑matching layers in telecommunication and military technologies has gained substantial importance. In this study, a multiphase nanocomposite comprising Fe₃O₄, ZnTiO₃, and multi‑walled carbon nanotubes (MWCNT) embedded within an epoxy resin matrix was designed and synthesized under carefully controlled laboratory conditions. Experimental data were analyzed using multiple regression analysis alongside error variance reduction techniques to identify the optimal composition among the four finalized sample variants. During the fabrication process, the samples underwent sequential mixing, heating, and sonication steps to ensure proper dispersion of the fillers, followed by casting into molds with dimensions corresponding to the rectangular waveguide test section used for the electromagnetic measurements.Topological and morphological characterizations of the fabricated composites were performed by Scanning Electron Microscopy (SEM), while crystal structure assessments employed X‑ray Diffraction (XRD) analysis. Furthermore, electromagnetic characterization was conducted using WR‑90 waveguide measurements over the frequency range of 8.2–12.4 GHz. Among the samples examined, specimen C4, containing an increased ZnTiO₃ content, demonstrated superior particle dispersion and consequently improved electromagnetic impedance‑matching performance. Numerical simulations carried out with the Frequency Domain Solver of CST Microwave Studio corroborated the experimental findings with considerable agreement. The results identified Fe₃O₄ as the dominant contributor to magnetic loss mechanisms, whereas MWCNTs served as conductive constituents within the composite matrix. The inclusion of ZnTiO₃ markedly enhanced impedance matching characteristics, resulting in a significant reduction of wave reflection and thereby facilitating improved wave energy transmission control across a broad bandwidth. Specifically, for the 1 mm thick C4 sample, the reflection coefficient was reduced to −17.85 dB, while the transmission parameter S₂₁ remained below −0.072 dB at 8.2 GHz, indicating excellent impedance matching and minimal reflective loss. Frequency‑dependent analysis further demonstrated a stable balance between dielectric and magnetic contributions, manifesting in consistent electromagnetic performance without substantial deviation across the measured spectrum. Accordingly, the investigated nanocomposite emerges as a promising candidate for lightweight, high‑performance absorber layers, impedance‑matching layers, and electromagnetic coatings in advanced telecommunication and defense applications.

Facile Synthesis and Optical Properties of Rod-like Copper Oxide Nanoparticles

Moges Tsega Yihunie

Copper oxide (CuO) nanoparticles (NPs) were synthesized by the sol-gel method, followed by calcination at 600 ^oC for 2 h. The XRD pattern indicated that the synthesized CuO NPs had a monoclinic structure, with an average crystallite size of 53 nm. The FT-IR spectra showed that surfactant molecules were adsorbed on the surface of the CuO nanoparticles, along with the presence of Cu-O bonding. The TEM analysis revealed rod-like CuO NPs with diameters of about 50 nm and lengths ranging from 150 to 200 nm. The XPS analysis confirmed that copper and oxygen were synthesized as the main components with Cu²⁺ and O^2-oxidation states. The optical band gap of CuO was calculated to be 3.5 eV. The maximum PL emission was recorded at 430 nm for the 365 nm excitation wavelength, and the change in PL intensity and peak shift was calculated as a function of excitation wavelength. The Mie analysis results also showed that when crystallite sizes increased, so did the maximum values of extinction efficiency, scattering efficiency, asymmetry, and scattering matrix. The findings of this study imply that CuO NPs could be a viable choice for a variety of luminous device applications.

The Effect of lanthanum Substitution on the Ferroelectric and Piezoelectric Properties of (Pb0.88Sr0.12)(Zr0.54Ti0.44Sb0.02)O3 Ceramics

Saeid Baghshahi

Piezoelectric ceramics based on lead zirconate titanate (PZT) with a composition of (Pb_0.88-3x/2Sr_0.12La_x)(Zr_0.54Ti_0.44Sb_0.02)O₃ where x=0.0, 0.005 and 0.01 were synthesized using conventional solid state sintering at 1280°C. The effect of lanthanum substitution on the microstructure, ferroelectric and piezoelectric properties of the samples was studied. The results showed that lanthanum substitution was beneficial for densification of the samples during sintering and the samples with 1.0 mole% lanthanum exhibited the maximum density of 7.34 g.cm^-3 when sintered at 1280°C. Moreover, the piezoelectric coefficient (d₃₃), relative dielectric constant (e_r), dielectric loss (tanδ), electromechanical coupling coefficient (k_p) and the Curie temperature (T_C) of the samples reached the optimal values of 635 pC/N, 3000, 0.018, 0.67 and 195°C respectively at 0.5 mole% lanthanum substitution. Furthermore, the bulk density (ρ) was 7.31 g.cm^-3 for the same sample. The results indicate that the lanthanum doped PSZTS ceramics can be hopefully used in applications such as pulsed transmitting transducers, high sensitivity receivers and actuators with large displacements.

Synthesis of Carbon Black/Geopolymer Composites with High and Stable Electrothermal Performance

Imad Disher

Geopolymer/nano carbon black composite is a promising electrically conductive smart material that can be used in self-heating and self-sensing applications. This paper studies the effect of adding nano carbon black to the physical, mechanical, electrical, and electrothermal performance of metakaolin-based geopolymer. Carbon black was added at the percent of 5%, 10%, 15%, and 20% by weight of metakaolin; the compressive strength was tested at various ages of 7, 14, 28, and 90 days, and the electrothermal performance was tested using AC and DC voltages. The results showed that a compromise between suitable compressive strength and high electrothermal conversion could be achieved when a specific balance between the carbon black percent and the lowest water content is established. A composite with a compressive strength of 27 MPa and stable electrothermal performance reaching 142°C at 9V DC can be prepared using 20 wt% of carbon black and a water-to-metakaolin ratio of 0.549, which is used as a smart material in construction applications.