Showing 160 results for Sit
Muhammad Shahzad Sadiq, Muhammad Imran, Abdur Rafai, Muhammad Rizwan,
Volume 21, Issue 2 (6-2024)
Abstract
With increasing energy demand and depletion of fossil fuel resources, it is pertinent to explore the renewable and eco-friendly energy resource to meet global energy demand. Recently, perovskite solar cells (PSCs) have emerged as plausible candidates in the field of photovoltaics and considered as potential contender of silicon solar cells in the photovoltaic market owing to their superior optoelectronic properties, low-cost and high absorption coefficients. Despite intensive research, PSCs still suffer from efficiency, stability, and reproducibility issues. To address the concern, the charge transport material (CTM) particularly the electron transport materials (ETM) can play significant role in the development of efficient and stable perovskite devices. In the proposed research, we synthesized GO-Ag-TiO2 ternary nanocomposite by facile hydrothermal approach as a potential electron transport layer (ETL) in a regular planar configuration-based PSC. The as synthesized sample was examined for morphological, structural, and optical properties using XRD, and UV-Vis spectroscopic techniques. XRD analysis confirmed the high crystallinity of prepared sample with no peak of impurity. The optimized GO-Ag-TiO2 ETL exhibited superior PCE of 8.72% with Jsc of 14.98 mA.cm-2 ,Voc of 0.99 V, and a fill factor of 58.83%. Furthermore, the efficiency enhancement in comparison with reference device is observed which confirms the potential role of doped materials in enhancing photovoltaic performance by facilitating efficient charge transport and reduced recombination. Our research suggests a facile route to synthesize a low-cost ETM beneficial for the commercialization of future perovskite devices.
Seyed Farzad Dehghaniyan, Shahriar Sharafi,
Volume 21, Issue 2 (6-2024)
Abstract
Mechanical alloying was employed to synthesize a nanostructured alloy with the chemical formula of (Fe80Ni20)1-xCrx (x= 0, 4). The microstructural and magnetic properties of the samples were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), and a vibrating sample magnetometer (VSM). Additionally, theoretical calculations were performed using density functional theory (DFT) under the generalized gradient approximation (GGA). Simulations have demonstrated that an appropriate quantity of chromium (Cr) can dissolve within the BCC-Fe (Ni) structure, resulting in a favorable enhancement of the magnetic moment of the lattice. The XRD results indicated that after 96 hours of milling, Fe (Ni) and Fe (Ni, Cr) with a body-centered cubic (BCC) structure were formed. With increasing milling time, the grain size decreased while the microstrain increased. The saturation magnetization (Ms) of Fe80Ni20 composition increased up to 32 hours of milling, but further milling (up to 96 h) resulted in a decrease in the saturation magnetization However, for the (Fe80Ni20)96Cr4 powders, milling up to 64 h caused a reduction in Ms. The coercivity (Hc) trend was different and increased with longer milling times (up to 96 h) for both compositions.
Alireza Zibanejad-Rad, Ali Alizadeh, Seyyed Mehdi Abbasi,
Volume 21, Issue 2 (6-2024)
Abstract
Pressureless sintering was employed at 1400 °C to synthesize Ti matrix composites (TMCs) reinforced with in-situ TiB and TiC reinforcements using TiB2 and B4C initial reinforcements. The microstructure and wear behavior of the synthesized composites were evaluated and compared and the results showed that B4C caused the formation of TiB-TiC in-situ hybrid reinforcements in the Ti matrix. Also, TiB was in the form of blades/needles and whiskers, and TiC was almost equiaxed. Moreover, the volume fraction of the in-situ formed reinforcement using B4C was much higher than that formed using TiB2. In addition, although the hardness of the B4C-synthesized composites was higher, the composite synthesized using 3 wt.% TiB2 exhibited the highest hardness (425 HV). The wear test results showed that the sample synthesized using 3 wt.% TiB2 showed the lowest wear rate at 50 N, mainly because of its higher hardness. The dominant wear mechanism in the samples synthesized using 3 wt.% B4C was abrasive and delamination at 50 N and 100 N, respectively while in the samples synthesized 3 wt.% TiB2, a combination of delamination and adhesive wear and adhesive wear was ruling, respectively.
Satish Ahire, Ashwini Bachhav, Bapu Jagdale, Thansing Pawar, Prashant Koli, Dnyaneshwar Sanap, Arun Patil,
Volume 21, Issue 2 (6-2024)
Abstract
Hybrid photocatalysts, comprising both inorganic and organic polymeric components, are the most promising photocatalysts for the degradation of organic contaminants. The nanocomposite, Titania-Polyaniline (TiO2-PANI) was synthesized using the chemical oxidative polymerization method. Various characterization techniques were employed to assess the properties of the catalysts. The ultraviolet diffuse reflectance spectroscopy (UV-DRS) analysis revealed that the TiO2 absorbs only UV light while the TiO2-PANI nanocomposite absorbs light from both UV and visible regions. The X-ray diffraction (XRD) results confirmed the presence of TiO2 (anatase) in both TiO2 nanoparticles and TiO2-PANI (Titania-Polyaniline) nanocomposite. The phases of the catalysts were verified through Raman, TEM, and SAED techniques where all results are in good agreement with each other. The average crystallite size of TiO2 nanoparticle and TiO2-PANI nanocomposite were 13.87 and 10.76 nm. The thermal stability of the catalysts was assessed by the Thermal gravimetric analysis (TGA) technique. The order of the thermal stability is TiO2 > TiO2-PANI > PANI. The crystal lattice characteristics were confirmed using Transmission electron microscopy (TEM). The surface area measurements were confirmed from the Brunauer-Emmett-Teller (BET) study and were employed for the evaluation of the photocatalytic efficiency of both, TiO2 nanoparticles and TiO2-PANI nanocomposite catalysts. The energy dispersive spectroscopy (EDS) study was employed for elemental detection of the fabricated materials. While Raman spectroscopy was employed for the chemical structure and the phase characteristics of the materials. The standard conditions for the degradation of the CF dye were 8 g/L of catalyst dosage, 20 mg/L of dye concentration, and a pH of 7. The TiO2-PANI nanocomposite exhibited superior efficiency as compared to pure TiO2 nanoparticles, achieving almost 100 % degradation in just 40 minutes.
Wed Abed, Haider Abdulelah, Sanaa Q.badr,
Volume 21, Issue 2 (6-2024)
Abstract
Hadi Sharifidarabad, Alireza Zakeri, Mandana Adeli,
Volume 21, Issue 3 (9-2024)
Abstract
The sensitivity of lead dioxide coating properties to the deposition conditions and electrolyte composition has allowed the preparation of coatings with different properties for different applications. In this study, the effects of electrolyte additives on the electrodeposition process were investigated using electrochemical measurements such as cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. The results showed that the presence of fluoride ions significantly reduce the possibility of TiO2 formation. The addition of copper ions not only prevents lead loss at the cathode, but also leads to the formation of copper oxide on the surface at initial stages, which hinders nucleation of PbO2. The presence of sodium dodecyl sulfate (SDS) also interferes with the nucleation process as it occupies active nucleation sites. The α-PbO2 interlayer prevents copper oxidation and solves the problem of lead dioxide nucleation. Finally, it was found that the simultaneous use of all additives together with the α-PbO2 interlayer has a positive effect on the coating process.
Hossein Momeni, Sasan Ranjbar Motlagh,
Volume 21, Issue 3 (9-2024)
Abstract
The present work deals with the hot deformation behavior of commercial Nb alloy C-103 and its microstructure evolution during uniaxial compression tests in the temperature range of 700-1100 °C and the strain rate range of 0.001-0.4 s-1. Strain rate sensitivity, calculated from the compression tests data, was almost constant and showed a negative value in the temperature range of 700-900 °C but increased significantly beyond 900 °C. Dynamic strain aging was found to have a predominant effect up to 900 °C, beyond which dynamic recovery and oxidation influenced the compressive properties. The microstructure of the deformed samples showed indications of dynamic recrystallization within the high strain rate sensitivity domain and features of flow instability in the regime of low strain rate sensitivity. The 950–1000 °C temperature range and strain rate range of 0.001-0.1 s-1 were suggested as suitable hot deformation conditions. The constitutive equation was established to describe the alloy's flow behavior, and the average activation energy for plastic flow was calculated to be 267 kJ/mol.
Tushar Wagh, Sagar Mane, Gotan Jain, Madhavrao Deore,
Volume 21, Issue 3 (9-2024)
Abstract
Nowadays metal oxide nanoparticles and transition metal dichalcogenides play a vital role in various areas like optical sensors, solar cells, energy storage devices, gas sensors and biomedical applications. In the current research work, we synthesized ZrSe2 nanoparticles by hydrothermal method. The ZrSe2 nanoparticles were synthesis using precursors such as ZrOCl2.8H2O and Na2SeO3.5H2O in the addition of surfactant cetyl trimethyl ammonia bromide CTAB and reductant hydrazine hydrate, respectively. By using synthesized ZrSe2 nanopowder thick films were developed on a glass substrate
using the screen printing method. The structural properties of ZrSe2 powder were studied by X-ray diffraction (XRD). The X-ray diffraction analysis revealed that the hexagonal crystal structure and crystalline size were found to be 55.75 nm. The thick films of ZrSe2 were characterized by field emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDAX). The surface morphological analysis of ZrSe2 nanostructured thick film shows hierarchical nanoparticles. The energy band gap of synthesized powder was calculated using a Tauc plot from UV-visible spectroscopy. The gas-sensing properties of ZrSe2 thick films were studied. The developed ZrSe2 thick films show maximum sensitivity and selectivity towards the ammonia NH3 gas at an operating temperature of 120 °C and the gas concentration was 500 ppm. The developed thick films show fast response and recovery time.Nowadays metal oxide nanoparticles and transition metal dichalcogenides play a vital role in various areas like optical sensors, solar cells, energy storage devices, gas sensors and biomedical applications. In the current research work, we synthesized ZrSe2 nanoparticles by hydrothermal method. The ZrSe2 nanoparticles were synthesis using precursors such as ZrOCl2.8H2O and Na2SeO3.5H2O in the addition of surfactant cetyl trimethyl ammonia bromide CTAB and reductant hydrazine hydrate, respectively. By using synthesized ZrSe2 nanopowder thick films were developed on a glass substrate
using the screen printing method. The structural properties of ZrSe2 powder were studied by X-ray diffraction (XRD). The X-ray diffraction analysis revealed that the hexagonal crystal structure and crystalline size were found to be 55.75 nm. The thick films of ZrSe2 were characterized by field emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDAX). The surface morphological analysis of ZrSe2 nanostructured thick film shows hierarchical nanoparticles. The energy band gap of synthesized powder was calculated using a Tauc plot from UV-visible spectroscopy. The gas-sensing properties of ZrSe2 thick films were studied. The developed ZrSe2 thick films show maximum sensitivity and selectivity towards the ammonia NH3 gas at an operating temperature of 120 °C and the gas concentration was 500 ppm. The developed thick films show fast response and recovery time.
Ahabboud Malika, Gouitaa Najwa, Ahjyaje Fatimazahra, Lamcharfi Taj-Dine, Abdi Farid, Haddad Mustapha,
Volume 21, Issue 4 (12-2024)
Abstract
This paper reports the preparation and characterization of (1-x) PbZr0.52Ti0.48O3 -xBiFeO3 (1-x)PZTxBFO) (x= 0.00, 0.15, 0.30, 0.45, 0.60 and 1.00) multiferroic ceramics which were prepared by a sol-gel method for PZT and hydrothermal reaction process for BFO. The perovskite structure of the composite system was confirmed by X-ray diffraction and Raman spectroscopy, while the composite microstructure w:as char:acterized by scanning electron microscopy. XRD results and Rietveld analysis for the (1-x)PZT-xBFO composites confirm the coexistence of these three phases; rhombohedral (R3m) and tetragonal phases (P4mm) for pure PZT and only the rhombohedral phase (R3c) for pure BFO. Raman spectroscopy of the (1-x)PZT-xBFO composites shows two clear bands around 150 and 180 cm-1. When the BFO content increases, the intensities of Raman modes are decreased. The SEM results suggested a formation of agglomerate and form into large complex clusters as BFO increased and a higher grain size was obtained for the BFO sample compared with the other composites. The EDS spectra of our pellets show that all the characteristic lines of the chemical elements Pb, Zr, Ti, and O and Bi, Fe, and O are present for the PZT and BFO materials respectively. The temperature-dependent dielectric constant shows different behavior dependent on BFO content. Indeed, the dielectric properties are found to be improved with an increase in dopant concentration of BFO in PZT, and novel dielectric behavior, resonance, and antiresonance, were obtained.
Ferda Mindivan,
Volume 21, Issue 4 (12-2024)
Abstract
Natural-reinforced hybrid composites, called "eco-materials," are becoming increasingly important for protecting the environment and eliminating waste problems. In this study, hybrid biocomposites were produced by the colloidal mixing method using seashell (SS) as natural waste, two graphene derivatives (graphene oxide (GO) and reduced graphene oxide (RGO)) as filler material, and polyvinyl chloride (PVC) as the polymer matrix. The crystallization and mechanical properties of hybrid biocomposites were examined based on their thermal properties using TGA and DSC analysis. In comparison to PVC/GO and PVC/RGO composites with identical weight percentages of GO and RGO, the PVC/GO composite exhibited superior thermal stability and crystallinity, resulting in elevated hardness values for the same composite. These results were attributed to the better interaction of GO with PVC due to the higher number of oxygen-containing functional groups in GO than in RGO. However, the PVC/RGO/SS hybrid biocomposites exhibited superior properties than PVC/GO/SS hybrid biocomposites. The greatest crystallinity values were 39.40% for PVC/RGO/SS-20 compared to PVC/RGO at 20 wt% SS content and 29.21% for PVC/GO/SS-20 compared to PVC/GO. The PVC/RGO/SS-20 hybrid biocomposite showed the greatest gain in hardness value, up 18.47% compared to the PVC/RGO composite. No significant change was observed in the melting and weight loss temperatures as the SS content increased; however, the crystallinity and glass transition temperatures in hybrid biocomposites increased as the SS content increased. All analysis results demonstrated the achievement of SS-graphene-PVC interactions, suggesting that SS waste could enhance the thermal and mechanical properties of composite production.
Maryam Hajiebrahimi, Sanaz Alamdari, Omid Mirzaee,
Volume 21, Issue 4 (12-2024)
Abstract
Dual nanocomposites based on metal sulfide nanomaterials with a narrow band gap are favorable candidates for future optoelectronic applications and ionizing ray sensors. In this study, novel silver-doped zinc sulfide/ cadmium sulfide (ZnS/CdS: Ag) nanocomposites were synthesized using the cost-effective solvothermal approach. For the first time, the radiation sensitivity of the newly developed nanocomposite was assessed using a 241Am alpha source and ion beam-induced luminescence (IBIL) measurements. The ZnS/CdS: Ag nanocomposite demonstrated significant light emission in the blue-green spectrum when measured at room temperature. When exposed to alpha irradiation, the ZnS/CdS: Ag nanocomposite film displayed exceptional sensitivity compared to pure ZnS or CdS films. The FESEM images revealed a uniform distribution of semi-spherical and rod-shaped nanoparticles, with an average particle size measuring 180 nm. The results from XRD and EDX demonstrated distinct peaks corresponding to ZnS, CdS, and associated elements within the nanocomposite. The existence of several groups within the nanocomposite was confirmed through Fourier transform infrared spectroscopy. Evaluations revealed that the optical quality of the ZnS/CdS: Ag nanocomposite showed enhancement in comparison to pure ZnS and CdS. The results suggest that the ZnS/CdS: Ag nanocomposite film holds great promise for applications in optoelectronic devices and detection technologies.
Mehdi Mehranian, Hajar Ahmadimoghadam,
Volume 21, Issue 4 (12-2024)
Abstract
In this research study, a composite coating of Ni-Co/SiC-CeO2 was prepared on a copper substrate using the pulse electrodeposition technique. The effects of electrodeposition parameters, including current density, duty cycle, and frequency, on the properties of the prepared coating were investigated. The selected current density values were 0.1, 0.2, and 0.3 A/cm2, the duty cycle options were 10, 20, and 30%, and the frequency values were 10, 100, and 1000 Hz. Increasing the current density enhanced the microhardness of the coating but reduced its corrosion resistance. This behavior can be attributed to the grain refinement occurring within the coating as the current density increases. On the other hand, an increase in duty cycle resulted in a decrease in microhardness, which can be attributed to a decrease in the concentration of nanoparticles within the coating. The lower corrosion resistance observed at higher duty cycles could be attributed to the decrease in off-time, causing the pulse electrodeposition conditions to approach a DC (direct current) state. Furthermore, higher frequencies were found to be associated with increased microhardness and improved corrosion resistance of the coatings. The coatings with the highest corrosion resistance exhibited a corrosion current density of 0.29 µA/cm2 and a polarization resistance of 1063 Ω.cm2 in a 3.5% NaCl solution. These coatings were prepared using a current density of 0.2 A/cm2, a duty cycle of 10%, and a frequency of 1000 Hz.
Muhammad Rizwan,
Volume 22, Issue 1 (3-2025)
Abstract
Powder-based Physical Vapor Deposition (PPVD) was utilized to deposit doped TiO2 thin layers, to modify electronic and optical properties. The modification was performed using different dopants (MnO2, Ta2O5, Nb2O5) at different concentrations (0.05 and 0.1 mol%) respectively. The structural characterization by FESEM reveals that the size of the grain varied with respect to the dopants. The sample doped at lower concentration demonstrates a larger crystallite size than the sample doped at higher concentration. This trend is consistent with the measured grain size of the doped thin layer samples. The nonlinearity coefficient (α) and breakdown voltage at lower ranges are enhanced as the dopant concentration in the TiO2 lattice increases due to the reduction of grain size. While, the optical properties of doped TiO2 thin layers with respect to energy bandgap demonstrated enhancement trend with the addition of the dopant as revealed by UV-Vis’s reflectance analysis. The enhancement of electrical and optical properties is contributed by the formation of barrier layer surrounding the grains, which in return increases the conductivity of the doped TiO2 thin layers sample. Conclusively, this study demonstrates the feasibility of the PPVD method in producing a dense thin layer structure for further optical and electrical based applications.
Adil Kadum Shakir, Ebrahim Ghanbari-Adivi, Aref S. Baron Baron, Morteza Soltani,
Volume 22, Issue 1 (3-2025)
Abstract
Nanomaterials have significantly transformed multiple scientific and technological fields due to their exceptional properties, which result from their quantum confinement effects and high surface-to-volume ratios. Among these materials, zinc oxide (ZnO) and titanium dioxide (TiO2) nanoparticles have attracted considerable interest because of their diverse applications.
In this study, TiO2-ZnO nanocomposites were synthesized using varying calcination times of 1, 1.5, 2, 2.5, and 3 hours. Characterization of fabricated samples through X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDXS) confirmed the successful fabrication of the nanocomposites. In this regard, XRD analysis revealed anatase TiO2 and hexagonal wurtzite ZnO phases. Raman spectroscopy also supported these findings, identifying characteristic peaks of both TiO2 and ZnO.
The calcination time had a minimal effect on the crystal structures and also morphology of the nanocomposites, which gave rise to its negligible impact on optical properties and biological activities of the samples. Optical properties assessed by means of UV-visible and photoluminescence (PL) spectroscopy showed consistent band gap absorption and emission profiles across all samples, among which the nanocomposite calcined for 1 hour exhibited the best optical properties.
The sample prepared at 1 hour not only showed the most favorable optical properties, but also demonstrated significant antibacterial, antifungal, and cytotoxic activities, which make it suitable for various applications. In this regard, a reduction of more than 99.9% occurred in the number of Escherichia coli and Staphylococcus aureus bacteria and also Candida albicans fungus by using TiO2-ZnO nanocomposite. Besides, addition of 500 µg/ml of nanocomposite decreased the cell viability to 34.47%, which signifies its high cytotoxicity activity.
Zeinab Abbasali Karajabad, Adrine Malek Khachatourian, Mohammad Golmohammad, Ali Nemati,
Volume 22, Issue 1 (3-2025)
Abstract
Hybrid asymmetric supercapacitors using distinct cathode/anode materials offer enhanced energy density by expanding operational potential windows compared to symmetric configurations. In this work rGO/α-Fe₂O₃ and rGO/TiO₂ nanocomposites were synthesized via hydrothermal method for hybrid asymmetric supercapacitors applications. Field emission scanning electron microscope (FESEM) revealed uniform distribution of spherical α-Fe₂O₃ and TiO₂ nanoparticles on rGO sheets. The X-ray diffractometry (XRD) analysis confirmed the presence of the hematite and anatase in the rGO/α-Fe2O3 and rGO/TiO2 nanocomposites, respectively. Additionally, in the XRD spectra of both nanocomposites, a broad peak corresponding to the (002) crystalline planes of rGO was observed. Electrochemical testing showed specific capacities of 130 F/g (rGO/α-Fe₂O₃) and 253 F/g (rGO/TiO₂) at 5 mV/s in 1M KOH. The assembled hybrid asymmetric supercapacitors (rGO/α-Fe₂O₃//rGO/TiO₂) achieved a 1.6 V operational potential window. Power density and energy density of 1066 W kg-1 and 9.7 Wh kg-1 were achieved at a current density of 1 A/g, respectively.
Mohammad Derakhshani, Saeed Rastegari, Ali Ghaffarinejad,
Volume 22, Issue 1 (3-2025)
Abstract
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.
Seyed Hossein Razavi, Amirhossein Riazi, Alireza Khavandi, Mostafa Amirjan, Mohsen Ostad Shabani, Hossein Davarzani, Yazdan Shajari,
Volume 22, Issue 2 (6-2025)
Abstract
Additive manufacturing (AM) of metallic parts has gained significant attention in recent years due to its ability to produce components without traditional tooling such as molds, melting furnaces, or extensive raw material preparation. Its unique capability to fabricate complex geometries has revolutionized part design and enabled substantial weight reduction. This review first outlines the development trajectory of metal-based AM, with a particular focus on laser-based fusion methods, including Laser Powder Bed Fusion (LPBF) and Direct Laser Deposition (DLD). Understanding this evolution helps researchers identify both the capabilities and limitations of AM technologies, thereby enhancing their application in areas such as prototyping, mass production, and repair. Each metal possesses unique physical and chemical properties, which often make traditional manufacturing methods more challenging—especially for alloys with high strength, hardness, or temperature resistance. In this context, the review then focuses on nickel-based superalloys (NBSAs), which are widely used in high-temperature and high-stress environments but are particularly difficult to process using conventional techniques. Their application serves as a representative case study for evaluating the performance and feasibility of AM techniques for advanced materials. Furthermore, the future prospects of AM are discussed, including advancements in monitoring systems, integration of machine learning, and the development of AM-specific alloys. As a novel aspect, this work compares LPBF and DLD in terms of their advantages, limitations, and resulting material properties, along with a comparison to traditional manufacturing methods such as casting and wrought processing.
Ali Keramatian, Mohammad Hossein Enayati, Fatemehsadat Sayyedan, Sima Torkian,
Volume 22, Issue 2 (6-2025)
Abstract
The aim of this study was to investigate the effect of current density on the microstructure of electrodeposited Ni–WC–TiC composite coatings on 304 stainless steel and compare the corrosion resistance of the coating and substrate in a 3.5 wt.% sodium chloride solution. A Watts nickel bath was employed under direct current (DC) conditions. Microstructure, elemental composition, and phase composition analyses were conducted using scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD), respectively. The results revealed that the coating formed at a current density of 40 mA/cm² exhibited a denser microstructure with higher cohesion and uniformity compared to coatings produced at other current densities. The corrosion resistance of the coating and substrate was evaluated using Tafel and electrochemical impedance spectroscopy (EIS) analyses. The corrosion test results indicated that the substrate exhibited superior corrosion resistance compared to the coating. Based on the dynamic polarization test plots, the corrosion mechanism of the substrate is active-quasi passive, with a pseudo-passive layer forming on the sample which remains stable within the potential range of -0.17 to 0.17 V. Beyond this potential range, the sample becomes susceptible to pitting. In the coated sample, the corrosion behavior is similar to that of the substrate, with the exception that the pseudo-passive layer remains stable within a narrower potential range of -0.19 to 0.08 V.
Nur Aziah Suhada Naim, Muhammad Faiq Abdullah, Sung Ting Sam, Wan Ahmad Radi Wan Ahmad Yaakub,
Volume 22, Issue 2 (6-2025)
Abstract
Despite being an effective material for food packaging, chitosan (CS) exhibited poor ductility when processed into film, which restricted its use in this industry. In this study, composite films with enhanced properties were developed by incorporating polyvinyl alcohol (PVA) into CS through a simple solution casting method. The effects of different PVA/CS weight ratios (70:30, 50:50, and 30:70 w/w) on the morphology, mechanical properties, antibacterial activity, and soil degradation of the composite films were analyzed. Compared to the pristine PVA film, increasing the CS content in the PVA/CS composite film enhanced thickness, stiffness, roughness, antibacterial efficiency, and degradation rate, while reducing tensile strength and elongation at break. Fourier transform infrared (FTIR) spectroscopy revealed the highest intermolecular interactions in the PVA/CS composite film with 70:30 w/w. Antibacterial activity tests and soil burial analysis demonstrated that the PVA:70/CS:30 composite exhibited significantly higher antibacterial activity toward Escherichia coli and Bacillus subtilis bacteria as opposed to PVA film, along with a moderate degradation rate of 76.76% following 30 days soil burial, effectively balancing biodegradability and material integrity. These findings suggest that the PVA:70/CS:30 composite is a promising alternative for sustainable and functional biodegradable packaging solutions.
Amin Rezaei Chekani, Malek Naderi, Reza Aliasgarian, Yousef Safaei-Naeini,
Volume 22, Issue 2 (6-2025)
Abstract
This paper presents the novel fabrication method of a three-dimensional orthogonally woven (3DW) C/C-SiC-ZrB2 composite and the effects of ZrB2 and SiC particles on microstructure and the ablation behavior of the C/C–SiC–ZrB2 composite are studied. C/C–SiC–ZrB2 composite was prepared by isothermal-chemical vapor infiltration (I-CVI), slurry infiltration (SI), and liquid silicon infiltration (LSI) combined process. Pyrolytic carbon (PyC) was first infused into the 3DW preform by I-CVI at 1050°C using CH4 as a precursor in order to form a C/C preform with porous media. The next step was graphitization at 2400°C for 1hr. Then ZrB2 was introduced into 3DW C/C preform with a void percentage of 48 by impregnating the mixture of ZrB2 and phenolic resin, followed by a pyrolysis step at 1050°C. A liquid Si alloy was infiltrated, at 1650 °C, into the 3DW C/C composites porous media containing the ZrB2 particles to form a SiC–ZrB2 matrix. An oxyacetylene torch flame was utilized to investigate The ablation behavior. ZrB2 particles, along with the SiC matrix situated between carbon fiber bundles, form a compact ZrO2-SiO2 layer. This layer acts as a barrier, restricting oxygen infiltration into the composite and reducing the erosion of carbon fibers. The findings were supported by FESEM imaging and further confirmed through x-ray diffraction and EDS analysis. The addition of ZrB2 to the C/C-SiC composite resulted in a lower mass and linear ablation rate; 2.20 mg/s and 1.4 µm/s respectively while those for C/C-SiC composite were 4.8 mg/s and 6.75 µm/s after ablation under an oxyacetylene flame (2500°C) for 120 s.
