High-alumina (Al2O3) ceramics are an important, but sometimes overlooked industrial material. Two 92% alumina spray-dried granules, which contained different sintering aid compositions, were studied. The two alumina granules, called MT and JP, were die compacted to form bend bars and heated at temperatures from 200℃ to 1600℃. The effect of the sintering aid composition on the shrinkage, density, and fracture strength of samples were investigated. It was found that MT samples had a lower density than the JP samples up to 1100℃, due to a greater weight loss following binder removal. However, between 1200℃ to 1600℃, the MT samples had higher density (95.45%. vs. 94.40%), shrinkage (18.1% vs. 14.4%), and fracture strength (315 MPa vs. 264 MPa) than the JP samples, due to a 100℃ lower onset of liquid phase sintering. An analysis using glass formation principles determined that the MT sintering aid contained more glass network modifiers and property modifiers, which likely reduced the sintering liquid formation temperature and viscosity.
This study presents the green synthesis of zinc oxide nanoparticles (ZnO-NPs) using mango peel extract (MgE) as a natural reducing and stabilizing agent. Phytochemical extraction was performed with deionized water, ethanol, and methanol for 1 h to 5 h, with deionized water at 4 h yielding the highest flavonoid content. Using zinc nitrate as a precursor, 25 mL of MgE successfully facilitated the synthesis of ZnO-NPs (ZnO-25MgE). It was found that annealing temperature at 400℃ for 6 h produced pure ZnO. The obtained nanoparticles were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and field emission scanning electron microscopy (FE-SEM). XRD confirmed the crystalline structure with an average size of 6.67 nm, while FT-IR and FE-SEM analyses revealed Zn–O vibrations, residual organics, and nanoscale morphology. Thermogravimetric analysis (TGA) indicated the appropriate annealing temperature for the removal of organics. For comparison, chemically synthesized ZnO was also characterized, and its antibacterial activity was assessed via disc diffusion against Escherichia coli and Staphylococcus aureus. The results demonstrated notable inhibition, highlighting the potential of biosynthesized ZnO-NPs for antimicrobial applications.
This study aims to investigate the effect of montmorillonite on the surface characteristics and porosity of bacterial nanocellulose (BNC) membranes derived from pineapple peel waste. The bacterial cellulose was synthesized using Acetobacter xylinum using pineapple peel extract as medium component. Bacterial nanocellulose membrane (BNC) was obtained by crushing and homogenizing bacterial cellulose in a high-pressure homogenizer. BNC membrane was reinforced with montmorillonite content of 2 wt% to 8 wt%. The membrane was characterized for its properties using SEM, FTIR, surface roughness tester, tensile tester, water holding capacity test, and BET analysis. The results showed that montmorillonite was well-dispersed within BNC matrix but exhibited agglomeration at higher concentrations. When the samples were analyzed using FTIR spectroscopy, observed changes in functional groups and molecular interactions at 2845 cm‒1 Alkane C‒H bond, confirming that components were successfully integrated. The surface roughness increased significantly from 28.33 ± 3.35 μm (control) to 82.23 ± 1.82 μm (8 wt% montmorillonite), confirming morphological change. The addition of montmorillonite has reduced the crystalline index and the mechanical properties of BNC membrane. BET analysis revealed a transition from microporous (1.6979 nm) to mesoporous structures (up to 2 nm) with enhanced surface area and pore diameter. Pore diameter and volume correlated with enhancing water holding capacity by 36.6% at montmorillonite content of 6 wt%. BC/montmorillonite membranes exhibit adjustable surface characteristics and porosity, thus providing potential for water treatment applications.
This study investigates the fabrication and mechanical characterization of Al5052 composites reinforced with nanosized TiB2 and ZrO2 particles via stir casting. Al5052 was chosen for its high strength-to-weight ratio and corrosion resistance, making it suitable for marine and automotive applications. The addition of hard ceramic reinforcements aimed to enhance mechanical properties without severely affecting ductility. Composite samples were tested as per ASTM standards. SEM analysis confirmed sound metallurgical bonding and generally uniform particle distribution. Density tests showed slight differences between theoretical and experimental values, with porosity generally increasing with reinforcement addition, attributed to particle agglomeration at higher loadings. Mechanical testing revealed an 18% increase in ultimate tensile strength for the hybrid composite with 1% TiB2 and 1.5% ZrO2. However, higher ZrO2 content reduced ductility. Hardness improved significantly, with up to a 42% increase with ZrO2 over the base alloy. Impact strength rose by over 69% with TiB2 but declined at high ZrO2 levels due to brittleness; hybrid composites showed moderate performance. Overall, the integration of nano-TiB2 and nano-ZrO2 into Al5052 enhanced strength and hardness, indicating strong potential for lightweight, high-performance applications in structural engineering, particularly in marine and automotive fields.
Gd2MoO6:Eu3+ phosphor-in-glass (PIG) composites were synthesized by a microwave-assisted melting technique using a 50SiO2:20TeO2:15Na2O:15BaO glass matrix containing 0.00 wt% to 10.00 wt% phosphor. Their structural, optical, and luminescent properties were systematically investigated. X-ray diffraction confirmed the formation of crystalline Gd2MoO6 phases, which became prominent at 5.00 wt% and 10.00 wt%, indicating partial crystallization within the glass network. The density and refractive index increased from 3.621 g∙cm‒3 to 3.774 g∙cm‒3 and 1.535 to 1.692 with higher phosphor loading, suggesting a more compact structure. Absorption spectra showed four characteristic Eu3+ bands at 464 nm, 534 nm, 2088 nm, and 2203 nm, while excitation monitored at 613 nm exhibited the strongest band at 394 nm (7F0→5L6). Emission spectra revealed intense red emissions at 590 nm, 613 nm, 653 nm, and 702 nm, corresponding to the 5D0→7F1–7F5 transitions, with chromaticity coordinates of (x, y) = (0.65, 0.34). The photoluminescence lifetime, measured under 394 nm excitation and monitored at 613 nm emission, decreased slightly from 1.719 ms to 1.585 ms. Vickers hardness values measured under a 0.2 kgf load ranged from 1601.7 HV0.2 to 1606.1 HV0.2, indicating high mechanical durability. Overall, the obtained PIG composites show strong red emission and robust structural properties, demonstrating their potential for solid-state lighting applications.
Aluminum dross is a hazardous byproduct from aluminum industry that causes environmental problems and high disposal cost. This work presents a sustainable route to upcycle secondary aluminum dross into lightweight ceramic foams for insulating refractory applications. Secondary aluminum dross powder was blended with polyethylene (PE) pore-forming agents (30 vol% to 70 vol%) and polyvinyl alcohol (PVA) binder added as a 7.5 wt% aqueous solution (binder contents: 1 vol% and 3 vol%), followed by pressing and sintering at 1400℃. Increasing PE systematically reduced bulk density and increased open porosity. At 70 vol% PE, the foams reached a bulk density of 0.94 g∙cm‒3 and open porosity of ~74%, satisfying the Japanese Industrial Standard (JIS) specification for lightweight refractory bricks. The maximum compressive strength was ~2 MPa, sufficient for thermal insulation where load-bearing capacity is secondary. X-ray diffraction confirmed a multiphase matrix of α−Al2O3, MgAl2O4, and CaAl12O19, indicating solid-state reactions between alumina and Mg/Ca-bearing phases. Morphology revealed a well-connected porous network stabilized by reaction-bonded bridges, indicating strong interparticle bonding and limited pore coalescence during sintering. This approach can divert over 1000 kg of hazardous waste per ton of secondary aluminum dross processed and cut CO2 emissions by 65% versus alumina routes. The approach promotes circular economy through waste-derived ceramics.
Plastic scintillators are widely used in radiation detection due to their low cost, fast response, and ease of fabrication, although their performace is often limited by low density, low atomic number, make them less efficient for applications requiring high-energy radiation. In this study, LaMnO3 was synthesized using the hydrothermal method and employed as a dopant to enhance the optical and scintillation properties of epoxy-based plastic scintillators. Structural, morphological, and optical characterizations of LaMnO3 were carried out using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS), UV-Vis and photoluminescence (PL) spectroscopy. The results confirm that the synthesized LaMnO3 exhibits a single-phase rhombohendral structure with irragular particle morphology, a direct band gap of 5.48 eV, and broad emission spanning 400 nm to 900 nm. XPS results revealed the coexistence of Mn3+ and Mn4+ oxidation states, induced by oxygen vacancies in the LaMnO3 lattice. Plastic scintillators were fabricated using epoxy as the matrix, 2,5-Diphenyloxazole (PPO) as the primary scintillator, 1,4-bis(5-phenyloxazol-2-yl)benzene (POPOP) as the wavelength shifter and LaMnO3 as the dopant. UV-Vis and PL measurements show that incorporating LaMnO3, increases optical absorbance, enhances emission intensity, and broadens the emission range, demonstrating more efficient radiative recombination within the scintillator. Pulse-height spectra obtained using photomultiplier tube (PMT) and a 60Co gamma source reveal a clear shift toward higer channels and increase in total counts for the LaMnO3-doped scintillator, confirming improved light output and energy transfer efficiency. Detection efficiency calculations further show that the LaMnO3-doped scintillator achieves 11.59% higher than the 9.86% of the undoped scintillator.
This study attempted to seek and verify the scientific aspects responsible for crawling in ceramic glazes. The selected additive was magnesium oxide (MgO). The glazes were applied on porcelain biscuits and fired between 1100℃ and 1300℃. The degree of crawling was enhanced with increasing amount of MgO, which was accompanied by formation of forsterite (Mg2SiO4) as a major phase. Complete island separation was achieved with 10 wt% MgO with good wettability and shiny surface. The morphology of the glaze demonstrated this phase as small crystals within the glaze layer. Addition of MgO resulted in a continuous decrease in the thermal expansion coefficient (as low as 11.76 ´ 10‒6 1∙℃‒1) likely due to crystallization of different phases. On the contrary, both glass-transition and softening temperatures (Tg and Ts) showed an initial decrease when adding 5 wt% MgO. However, the trend was reversed beyond the amount of 10 wt%. The in-depth study of the glass structure could not be carried out as the crystalline phase generating Raman peaks that interfered the deconvolution of the non-bridging oxygen (NBO) characteristics. The melting behavior displayed a similar trend to both Tg and Ts, signifying the complicated role of Mg cations in the glaze structure. Addition of MgO (5 wt%) could reduce the softening temperature from 1082℃ to 987℃ suggested that a small amount of MgO could likely behave as a network modifier. A higher amount modified the glaze structure to be closer to a glass-creamic. This change in phasic nature was likely to yield the glazes with high rigidity, high surface tension via melting difficulty which were closely reflected by the increase in the thermal expansion coefficient as well as Tg and Ts. Formation of crystalline phases due to MgO addition was believed to mainly cause crawling as evidenced by various, relevant characterization techniques.
New graft copolymers were developed from low-density polyethylene (LDPE) and high-density polyethylene (HDPE) following an initial ozonation step to introduce reactive functional groups onto the polymer backbone. Among the two polymers, LDPE demonstrated superior susceptibility to ozonation, making it the preferred substrate for subsequent grafting. Grafting was then performed primarily on ozonized LDPE using various functional monomers, including acrylic acid (AA), 4-vinylpyridine (4VP), acrylonitrile (AN), chloromethylstyrene (CMS), as well as copolymers such as AA–vinylphosphonic acid (AA-co-VPA) and AN–vinylphosphonic acid (AN-co-VPA). Grafting was carried out using both solution and melt techniques. The resulting materials were characterized by elemental analysis and Fourier transform infrared (FT-IR) spectroscopy, confirming the incorporation of heteroatoms and the presence of characteristic functional groups. Grafting performed in solution consistently yielded higher efficiencies compared to melt grafting, likely due to improved monomer diffusion and enhanced reactivity of active sites. These graft copolymers exhibit significantly enhanced surface hydrophilicity due to the increased surface polarity and functional group diversity, positioning them as promising candidates for applications in water purification membranes, ion exchange resins, sensors, biomedical devices, and composite materials requiring enhanced interfacial interactions.
Naturally produced Hydroxyapatite (HAP) yields beneficial attributes with regards to its biological functions including cell compatibility, proliferation and osteoinduction. This study synthesized HAP from oyster shells as a calcium source with multiple hydrothermal reaction times including 1 h, 6 h and 24 h at 150℃. A wet precipitated control sample was produced at room temperature. Characterization using FTIR, XRD, SEM-EDX and BET were conducted, followed by a degradation analysis. Bio-compatibility study of Oys-HAP was performed against Saos-2 osteoblast-like cells. The results showed nano scaled elongated and oval-shaped Oys-HAP particles with high crystallinity, beta-type carbonated, non-stoichiometric Ca/P ratio with a maximum surface area of 41.39 m2·g‒1. Furthermore, Oys-HAP samples were non-toxic and significantly enhanced Saos-2 cell proliferation by 65.6% compared to the negative control. These findings demonstrate the potential of oyster shell-derived Oys-HAP as a sustainable and effective biomaterial for biomedical applications.
In this study, alumina nanoparticles were modified with stearic acid (SA) dissolved in ethanol solution via facile techniques, which were soaking and refluxing. The effects of these modification techniques on the thermal behaviors and the functional groups of the SA-modified alumina were investigated. Stearic acid was successfully modified onto alumina nanoparticles using both techniques. In comparison, the refluxing technique yielded a higher degree of SA modification, corresponding to a grafting density of 2.59 molecules·nm‒2, which is approximately twice that of the soaking technique. Then, the SA-modified alumina via refluxing technique was mixed with polydimethylsiloxane (PDMS) and spray coated on glass slides. The effects of coating layers and the SA-modified alumina content on the wettability and optical property were studies. The 4-layered coating containing 10 wt% of SA-modified alumina exhibited superhydrophobic property with a water contact angle of 150.0° and the contact angle hysteresis of 6.2°. It also showed excellent self-cleaning performance. However, transmittance of 4-layered coating reduced dramatically. The results showed that increasing the number of coating layers enhanced surface wettability but adversely affected optical transmittance due to increased light scattering. Therefore, a balance between wettability and optical transparency must be considered. These findings indicated that SA-modification effectively enhanced the hydrophobicity of alumina particles, and the incorporation of these SA-modified particles introduced sufficient roughness to further improve hydrophobicity. The progress in the surface modification and the utilization of a spray coating method highlight the potential for scalable and facile fabrication of superhydrophobic coating.
The formation of superhydrophilic surfaces on Ti-6Al-4V was achieved through anodization at different voltages, followed by heat treatment at 1000℃ for 2 h. This treatment not only enhanced surface crystallinity but also induced morphological changes. A comprehensive analysis of surface properties, including morphology, phase composition, elemental structure, surface roughness, and hydrophilicity, was conducted using OM, FE-SEM, EDX, XRD, AFM, 3D laser scanning confocal microscope, and contact angle measurements, respectively. The TiO2 anodized films exhibited enhanced crystallinity, increased surface roughness, and a higher oxygen-to-titanium ratio. As a result, the TiO2 anodized films showed consistent morphology and distribution of elements, with high temperature annealing leading to a transformation from amorphous to crystalline structures, accompanied by elevated surface roughness, and augmented hydrophilicity.
The development of efficient and environmentally friendly corrosion protection systems for metals in aggressive environments has become a critical area of research, particularly for stainless steel used in marine and industrial applications. In this study, a series of graphitic carbon nitride (g-C3N4) and zinc oxide (ZnO) composites with varying g-C3N4 weight ratios (10 wt% and 30 wt%), are integrated to form heterojunction structures with enhanced charge separation and interfacial activity. The g-C3N4/ ZnO (ZCN) composite thin films were prepared using a facile thermal mixing method and were characterized using XRD, SEM, BET, FTIR, UV-Vis, and PL to confirm their structural, morphological, and optical properties. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements of the ZCN thin films and 304 stainless steel samples under 3.5 wt% NaCl solution showed higher photocurrent density, more negative photopotential displacement, and lower charge-transfer resistance, confirming accelerated electron migration from the ZCN thin film to the stainless-steel substrate. The open circuit potential (OCP) of the steel shifted negatively under illumination, confirming the generation of photogenerated cathodic protection. These results highlight the critical role of the hybrid interface and optimized g-C3N4 content in improving light-driven corrosion protection systems. The 10 wt% g-C3N4/ZnO nanocomposite offers a promising approach for the development of efficient photo-electrochemical coatings aimed at protecting stainless steel in harsh electrolyte environments.
In this study, a GdTbDyErPr rare-earth high-entropy alloy (RE HEA) was successfully synthesized and its magnetic properties and magnetocaloric effect (MCE) were systematically investigated. The results indicate that the as-cast GdTbDyErPr RE HEA exhibits a single-phase hexagonal close-packed (HCP) structure with lattice parameters of a = 3.609 Å and c = 5.734 Å. Based on large parameter Ω, high mixing entropy (ΔSmix), and small parameters δ and εi, it can be inferred that the GdTbDyErPr alloy forms a disordered solid solution. The GdTbDyErPr RE HEA undergoes a first-order magnetic transition near about 143 K. The parameters |∆ |, RC, and RCP are determined to be 6.8 J∙kg‒1K‒1, 352 J∙kg‒1 and 462 J∙kg‒1 for GdTbDyErPr RE HEA under 0 T to 5 T. The facile synthesizability and remarkable MCE of the GdTbDyErPr RE HEA position it as a promising candidate for magnetic cooling technology
This work investigates the mechanical properties and microstructural evolution of the heat-affected zone of 9% Ni steel narrow-gap welded joints produced by the GMAW process with a rotating electrode, since no literature on this subject is available. This process is an innovation of the GMAW process, which permits narrow gap welding because the circular motion of the electrode overcomes the main issue of the sidewall's lack of fusion observed in the conventional process. However, the rotation movement of the electric arc imposes a higher peak temperature at the heat affected zone, which can negatively affect the mechanical properties. The joints were welded in the flat position, preheated to 100°C, with a rotation frequency of 1500 rpm, a rotation diameter of 3 mm, and an average heat input of 2 kJ·mm‒1. The results obtained in metallographic examination by electron microscopy and backscattering diffraction, and tensile and Charpy-V impact tests revealed similar behavior of the heat-affected zone compared with the base metal. Thus, it is concluded that the 9% Ni steel welded by the GMAW process with a rotating electrode can be an advantageous alternative due to its higher productivity and mechanical properties that meet the requirements for industrial applications.
Highly crystalline, smooth-surface, and thin zinc oxide (ZnO) films have been successfully deposited on flexible polyethylene terephthalate (PET) substrates using an optimized two-step RF magnetron sputtering technique at ambient temperature. The PET used in this study was a commercially available overhead projector film, which was not epiready-grade and had a lower melting point (similar to 150 degrees C). This issue made high-quality deposition more challenging. In the first step, a thin ZnO buffer layer was deposited at low RF power to provide a smooth and thermally stable surface. This layer served as both a structural template and a thermal barrier during the subsequent high-power deposition of the main ZnO film. Structural analysis confirmed that the buffer layer suppressed lattice mismatch and reduced residual stress. The resulting film showed low surface roughness and no cracking. These features exceeded those of films grown directly at high power, which suffered from poor surface morphology due to substrate deformation. Although the use of a polycrystalline buffer layer led to a reduction in optical transmittance from increased light scattering, the fine-grained structure contributed to improved mechanical stability and dielectric loss suppression. These characteristics made films particularly suitable for piezoelectric applications on flexible substrates. This proposed two-step technique effectively balanced between surface smoothness and structural quality and offered practical solution for the fabrication of high-performance films on thermally sensitive substrates.
This research is aimed to determine the best composition of composite fabricated by Spark Plasma Sintering (SPS) to produce a suitable substituent for bone. The applied powder was prepared by the SPS method and comprises hydroxyapatite (HA), yttria-stabilized zirconia (YSZ), and titanium (Ti). Different percentages of components were used to fabricate the composite samples. X-ray diffraction was used to determine the structural phase of the sintered samples while field emission scanning electron microscopy (FE-SEM) was employed for microstructural analysis of the specimens. The behavior of the samples was investigated during sintering. The gas release, displacements, and porosity percentage of the composite samples were also explored. Three-point bending test was utilized to determine the flexural strength whereas the hardness of the samples was determined by the Vickers method. Moreover, the CHANTIKUL method was used to evaluate the toughness of the samples. The results showed the best mechanical properties in the 90%HA-6%YSZ-4 %Ti sample.
This study investigates the mechanical and microstructural attributes of epoxy composites with hemp fiber reinforcements and incorporated aluminum oxide (Al2O3), silicon dioxide (SiO2), and magnesium oxide (MgO) nanoparticles at different weight fractions of 0.5 wt%, 1.0 wt%, and 1.5 wt%. Nano-fillers remarkably improved the composite performance, as indicated by tensile and flexural tests conducted by ASTM D3039 and ASTM D790 standards. The composite containing 1.5 wt% Al2O3 outperformed other nano filled composites with a tensile strength of 64 MPa and tensile modulus of 3.6 GPa, versus 52 MPa and 3.0 GPa for the unfilled hemp/epoxy composite. In parallel, flexural strength and modulus also improved from 78 MPa and 3.5 GPa (unfilled) to 93 MPa and 4.2 GPa with 1.5 wt% Al2O3. SEM images corroborated the improved interfacial bonding and diminished fiber pull-out in nano-filled composites. The addition of nanofillers, mainly Al2O3, greatly improved the structural integrity of the hemp-based green composites, allowing for their use in sustainable load-bearing engineering applications.
