Iranian Journal of Materials Science and Engineering

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In this research an ultra-fine grained composite structure consisting of an intermetallic matrix together with dispersed nano-sized Al2O3 obtained via mechanical activation of TiO2 and Al in a high energy ball mill and sintering of consolidated samples. Phase composition and morphology of the milled and sintered samples were evaluated by XRD and SEM techniques Thermal behavior of the powder sample milled for 8 hours was evaluated by DTA technique. DTA results showed that, the reaction happens in two steps. The first step is the aluminothermic reduction of TiO2 with Al. XRD observations reveals that minor amount of Ti3Al phase formed during reduction reaction together with TiAl and Al2O3 major phases. This intermetallic phase disappeared when sintering temperature was increased to 850 ºC. The second step in DTA is related to a reaction between residual Al in the system (partly dissolved in TiAl lattice) and the Ti3Al phase produced earlier at lower temperatures. SEM micrographs reveal that by completion of the reduction reaction more homogeneous and finer microstructure is observable in sintered samples.

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In this study, Ta powder was produced from Ta scarp via chemical processes using Mg and Ca powders. At first, Tantalum scraps were converted to Tantalum oxide (Ta₂O₅) at 1100˚C in an oxygen atmosphere. Tantalum oxide was reduced to Tantalum powder with Mg in a vacuum environment at 950 to 1200˚C for 3 hours. The obtained Ta powders further were reacted with Ca at 950˚C for 5 hours in a vacuum atmosphere. The powders were analyzed through X-ray diffraction patterns (XRD), scanning electron microscopy (SEM), as well as oxygen measurement. The results show that the average particles size of the produced Ta powders is about 58 nm with oxygen contents of 250 ppm.

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The low velocity impact (LVI) response of pure and glass fiber reinforced polymer composites (GFRP) with 0.1, 0.3 and 0.5 wt% of functionalized single-walled carbon nanotubes (SWCNTs) was experimentally investigated. LS-DYNA simulation was used to model the impact test of pure and incorporated GFRP with 0.3 wt% of SWCNT in order to compare experimental and numerical results of LVI tests. All tests were performed in two different levels of energy. In 30J energy, the specimen containing 0.5 wt% SWCNT was completely destructed. The results showed that the incorporated GFRP with 0.3 wt% SWCNT has the highest energy absorption and the back-face damage area of this sample was smaller than other specimens. TEM images from specimens were also analyzed and showed the incorporation of well-dispersed 0.1 and 0.3 wt% of SWCNT, while in specimens containing 0.5 wt% of CNT, tubes tended to be agglomerated which caused a drop in LVI response of the specimen. The contact time of impactor in numerical and experimental results was approximately equal; however, the maximum contact forces in LS DYNA simulation results were higher than the experimental results which could be due to the fact that in the numerical modeling, properties are considered ideal, unlike in experimental conditions.

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Neoplastic cells have co-opted inflammatory receptors and signaling molecules that potentiate inflammation. Activated inflammatory pathways lead to neo-angiogenesis, lymph-angiogenesis, immunosuppression, tumor growth, proliferation and metastasis. This cancer-sustaining inflammation is a critical target to arrest cancer growth. Multiple drug resistance, high cost, low oral bioavailability and serious side effects have rendered conventional cytotoxic chemotherapeutics less impressive. The aim of this research was to achieve cancer debulking and proliferation prevention by limiting ‘cancer-sustaining’ tumor niche inflammation through non-conventional oral approach employing anti-inflammatory agents and avoiding conventional cytotoxic agents. Synergistic anti-inflammatory agents, i.e. celecoxib as selective COX-2 inhibitor and montelukast as cysteinyl leukotriene receptor antagonist, were selected. Silver nanoparticles (AgNPs) were used as nanocarriers because of their efficient synergistic anti-neoplastic effects and excellent oral drug delivery potential. Specifically, selected drugs were co-conjugated onto AgNPs. Synthesized nanoparticles were then surface-modified with poly(vinyl alcohol) to control particle size, avoid opsonization/preferred cellular uptake and improve dispersion. Surface plasmon resonance analysis, particle size analysis, DSC, TGA, XRD, FTIR and LIBS analysis confirmed the successful conjugation of drugs and efficient polymer coating with high loading efficiency. In-vitro, the nanoparticles manifested best and sustained release in moderately acidic (pH 4.5) milieu enabling passive tumor targeting potential. In-vivo, synthesized nanoparticles exhibited efficient dose-dependent anti-inflammatory activity reducing the dose up to 25-fold. The formulation also manifested hemo-compatibility, potent anti-denaturation activity and dose-dependent in-vitro and in-vivo anti-cancer potential against MCF-7 breast cancer and Hep-G2 liver cancer cell lines in both orthotopic and subcutaneous xenograft cancer models. The anti-inflammatory nanoparticles manifested tumor specific release potential exhibiting selective cytotoxicity at cancerous milieu with slightly acidic environment and activated inflammatory pathways. The formulation displayed impressive oral bioavailability, sustained release, negligible cytotoxicity against THLE-2 normal human hepatocytes, low toxicity (high LD₅₀) and wide therapeutic window. Results suggest promise of developed nanomaterials as hemo-compatible, potent, cheaper, less-toxic oral anti-inflammatory and non-conventional anti-cancer agents.

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The present study aimed to assess the effect of replacing copper as a multi-functional ingredient in the brake pad material with potassium titanate platelet (PTP) and a particular type of ceramic fiber (CF) copper-free composite. Chase dynamometer tests were conducted to compare a brake padchr('39')s tribological behavior when PTP and CF are added to the composition with that of the copper-bearing pad. The results concluded that PTP and CF demonstrated promising outcomes such as a stable coefficient of friction (COF), lower wear rate, and better heat resistance in copper-free friction composite. Scanning electron microscope (SEM/EDS) analysis was conducted to investigate the role of main elements such as Ti, Fe, K, O, and C on the formation of contact plateaus (CPs) upon the worn surface of friction composites. PTP maintained both continuous contact and smooth friction braking application of a brake pad. The uniform distribution of Ti on the wear track on the disc worn surface depicts the role of PTPs on stabilizing the friction film formation and eventually on the stability of COF.

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We report a simple and practical approach for the easy production of superhydrophobic coatings based on TiO₂-SiO₂@PDMS. In this study, we used tetraethylorthosilicate (TEOS) and titanium tetraisopropoxide (TTIP) as a precursor for the sol-gel synthesis of SiO₂ and TiO₂, respectively. Afterward, the surface of nanoparticles was modified by 1,1,1,3,3,3-hexamethyldisilazane (HMDS) before being combined with polydimethylsiloxane (PDMS). The hydrophobic property of coatings was evaluated by static contact angle measurements. The phase composition and structural evolution of the coatings were examined by X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analysis. It was shown that changing the weight ratio of the solution composition of the coating can affect the hydrophobicity of the surface. The best sample has shown a superhydrophobic property with a 153˚ contact angle which contained (75%TiO₂-25%SiO₂) and PDMS at a weight ratio of 1:1. Moreover, the results showed that the superhydrophobic coating retains its hydrophobic properties up to a temperature of 450 ˚C, and at higher temperatures, it converts to a super hydrophilic with a water contact angle close to 0 ˚. The SiO₂-TiO₂@PDMS coating degrades methylene blue by about 55% and was shown to be capable of photocatalytically decomposing organic pollutants.

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Deformation-induced α΄-martensite generally forms at shear bands in the coarse-grained austenite, while it nucleates at grain boundaries in the ultrafine-grained (UFG) austenite. The available kinetics models are related to the nucleation on the shear band intersections, and hence, their application to investigating the kinetics of α΄-martensite formation for the UFG regime cannot be justified. Accordingly, in the present work, the general Johnson–Mehl–Avrami–Kolmogorov (JMAK-type) model was implemented for comparing the kinetics of α΄-martensite formation in the UFG and coarse-grained regimes using an AISI 304L stainless steel. On the experimental front, the X-ray diffraction (XRD) patterns and the electron backscattered diffraction (EBSD) maps were used for phase and microstructural analyses, respectively. It was revealed that the simple JMAK-type model, by considering the dependency of the volume fraction of α΄-martensite on the strain, is useful for modeling the experimental data, predicting the nucleation sites based on the theoretical Avrami exponents, and characterizing the transformation kinetics at low and high strains.

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In this study, an epoxy-based nanocomposite reinforced with copper oxide-graphene oxide hybrid was investigated. Initially, the hybrid powder of CuO–GO with a weight ratio of 9:1 was prepared. The hybrid filler with different weight percentages ranging from 0.1–0.5 was used to reinforce the epoxy resin. The prepared samples were analyzed using XRD, FTIR, FESEM, TEM, and tensile testing. According to the XRD results and SEM images, the hybrid powder was successfully prepared, and the mechanical testing results showed an improvement in tensile strength in the composite samples. The best composite sample in terms of tensile strength was the one containing 0.3 wt% of hybrid reinforcement, which exhibited a 73% increase in strength compared to the neat resin sample.

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In this research, a nickel-tungsten coating as a catalyst for hydrogen evolution reaction (HER) with different current densities was synthesized and the resulting electrocatalytic properties and morphology were assessed. Linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and chronoamperometry in 1 M NaOH were used to evaluate the electrocatalytic activity for HER. By increasing the current density of electrodeposition up to 500 mA/cm², a columnar morphology was observed. The cyclic voltammetry test (CV) revealed that when the plating current density increases, C_dl has increased from 248 to 1310 µF/cm² and the active surface area increases 5 times. The results showed that by modifying the coating morphology, the current density of the hydrogen evolution increased up to two times.
 

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In this research, the morphology of the Ni-W coating was modified by adding graphene oxide (GO) nanosheets in such a way that a foam-like structure with high porosity and holes in the form of intertwined tunnels was obtained. Different amounts of GO nanosheets were added to the plating bath and the resulting coating was examined. In order to estimate the electrochemically active surface area, the cyclic voltammetry (CV) test was used. Moreover, the linear polarization test (LSV) and chronoamperometry in 1 M NaOH were conducted to investigate the electrocatalytic activity for the hydrogen evolution reaction (HER). It was found that by adding 0.4 g/L GO to the electroplating bath, the electrocatalytic properties are doubled and the active surface of the electrode is significantly increased.
 

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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.
 

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The present work deals with the corrosion behavior and mechanical properties of a coted AZ31 magnesium alloy through plasma electrolyte oxidation (PEO) coating process in different alkaline electrolytes based on sodium silicate (Si-coating), sodium polyphosphate (P-coating) and sodium aluminate (Al-coating). The scanning electron microscopy (SEM) equipped with the energy dispersive x-ray spectroscopy (EDX) plus x-ray diffraction were recruited to investigate the morphology, chemical composition, and phase structure of coatings, respectively. Microscopic scrutiny revealed that the coating in the phosphate electrolyte was twice as thick and the relative porosity percentage was higher than those formed in the other electrolytes. The phase analysis indicated that the MgO was present as the prevailing phase in the Al-coating and P-coating. However, the dominant phase in the Si-coating was Mg₂SiO₄. Electrochemical testing was examined in a solution containing 3.5.wt% sodium chloride, showing improvements in corrosion resistance of coated alloys. These investigations confirmed that the corrosion resistance of Si-coating was dramatically higher than others which could be attributed to the presence of the dense and stable Mg₂SiO₄ phase as well as its relatively low porosity. According to the results of tensile tests, the coated samples had lower tensile strength and elongation than the uncoated one. The tensile strength and elongation diminished upon changing the electrolyte from Al-coating to P-coating, while the yield strength was almost similar. Further analyses indicated that the drop of tensile strength and elongation could be attributed to the presence of cracks and pores in the brittle ceramic PEO coating as stress concentration regions during deformation. Those areas are created due to thermal stress during the coating process and deformation in the elastic stage.
 

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In this study, RF magnetron sputtering was employed to create titanium dioxide (TiO₂) thin films doped with zirconium oxide (ZrO₂) (TZO) onto quartz and silicon substrates at 100^oC for the purpose of evaluating the effect of ZrO₂ doping on the microstructural, electrical, optical and gas sensing properties of the TiO₂ films. Different doping concentrations (0.0, 2.0 and 4.0 wt.%) were used to compare performances of the films with a thickness ranging between 147 nm to 178 nm. Structural and surface morphology characterizations of the prepared films were carried out by X-ray diffraction (XRD) and atomic force microscopy (AFM) techniques. The surface morphology of the prepared TZO films showed a gradual reduction in the grain size while the doping concentration increased. The optical characteristics of the films also exhibited an increasing trend in the optical band gap with the rising ZrO₂ concentration. TiO₂ films showed an n-type conductivity as confirmed by Hall's measurement. The results of the gas sensing experiments revealed that the sensitivity of the TZO films for the detection of ethanol vapor increased with an increase in the concentration of ZrO₂ dopant. Therefore, TZO film with 4.0 wt.% of ZrO₂ could be used as an effective sensor for detecting ethanol vapor.