Malaysian Journal of Microscopy

MORPHOLOGICAL, CHEMICAL, AND THERMO-MECHANICAL PROPERTIES OF TREATED UNTWISTED KENAF YARN

Syukrina Harun — 2026-06-08

Kenaf (Hibiscus cannabinus L.) is widely recognised for its high cellulose content, strength-to-weight ratio, and abundant availability. However, studies on the fundamental effects of water and thermal treatment on untwisted kenaf yarns remain limited. Hence, this study aims to investigate the behaviour of untwisted kenaf yarns under moisture and heat exposure by analysing their morphological, chemical, and thermo-mechanical properties. The control kenaf fibres and untwisted kenaf yarns subjected to water and heat treatments were characterised using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and tensile testing. SEM observations showed that water treated kenaf yarn exhibited more aligned, compact, and smoother fibre bundles than the loosely packed control kenaf fibres. The fibre diameter of the treated kenaf yarn was 12.46 % smaller than that of the control kenaf fibres. FTIR analysis showed an increase in the O-H stretching intensity (3330–3400 cm⁻¹) and a prominent C=O peak at 1730 cm⁻¹, indicating partial modification of hemicellulose and a rearrangement of hydrogen bonds within the treated kenaf yarn fibres. TGA results showed two degradation stages at around 240 °C and 311 °C, with the treated yarn exhibiting a higher total weight loss than the control fibres. Tensile testing revealed that the treated kenaf yarn exhibited a higher tensile stress of 101.73 ± 51.46 mN/Tex compared to the control kenaf fibres at 98.66 ± 22.35 mN/Tex, accompanied by a slight reduction in tensile strain from 1.028% to 1.025 %. Overall, the combined water and heat treatment improved fibre alignment, compactness, and tensile stress while slightly reducing ductility. These enhancements demonstrate the potential of this eco-friendly processing method to produce untwisted kenaf yarns.

SOIL BURIAL ASSESSMENT OF CROSSLINKED FUNGAL CHITOSAN COMPOSITE FILMS REINFORCED WITH CELLULOSE NANOCRYSTALS EXTRACTED FROM SUGARCANE BAGASSE

Madah Hussain — 2026-06-08

An increase in non-biodegradable plastic waste has driven the hunt for sustainable packaging solutions. This study developed biodegradable composite films using fungal chitosan (FCH) reinforced with cellulose nanocrystals (CNC) from sugarcane bagasse (SCB) and crosslinked with glutaraldehyde (GA). The films were prepared by solution casting and characterised for biodegradability and structural changes. The formulations evaluated included non-crosslinked neat FCH (FCH0), non-crosslinked composites with 1, 3, 5, and 7 wt% CNC (FCH-CNC1 to FCH-CNC7), and glutaraldehyde-crosslinked variants (GA-FCH0 and GA-FCH-CNC1 to GA-FCH-CNC7). A 15-day soil burial test confirmed that all films were biodegradable, though they degraded at different rates. FCH0 exhibited the highest susceptibility to microbial attack, with approximately 72 % weight loss. Visual inspection further showed that FCH0 developed more voids and cavities compared to composite films, indicating weaker resistance to microbial activity. In contrast, the crosslinked FCH/CNC composite films exhibited a controlled, significantly slower degradation rate, attributed to the formation of a dense polymer network via covalent imine linkages that restricted microbial enzyme penetration. The incorporation of CNC and GA enhanced structural stability, resulting in fewer surface defects and reduced weight loss during soil burial. Field Emission Scanning Electron Microscopy (FESEM) analysis confirmed surface disintegration and void formation in degraded samples, while Fourier Transform Infrared (FTIR) spectroscopy evidenced the cleavage of glycosidic bonds. The results suggest that crosslinking effectively modulates the biodegradation rate without compromising the material's eco-friendliness. These findings establish crosslinked FCH/CNC composites as a promising, durable, and sustainable alternative to conventional plastics for food packaging applications.

PREPARATION AND CHARACTERIZATION OF PVA/CELLULOSE NANOCRYSTALS/Ε-POLY-L-LYSINE BIOCOMPOSITES FOR POST-HARVEST PRESERVATION OF CHILLIES

Nur Aiman Mohamad Senusi — 2026-06-08

Post-harvest deterioration of highly perishable product, such as chillies, remains a major concern in global food supply chains, resulting in huge economic losses and food waste, as well as highlighting the need for sustainable alternatives to synthetic preservatives. This work created multifunctional biocomposite coatings using polyvinyl alcohol (PVA), cellulose nanocrystals (CNC), and ε-polylysine (ε-PL) to improve mechanical, barrier, and antibacterial properties. The films were created using high-shear homogenisation and thoroughly characterised with optical microscopy (OM), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). OM and SEM investigations showed uniform dispersion at ideal compositions and aggregation at greater ε-PL loadings. FTIR demonstrated significant intermolecular interactions via hydrogen bonding and electrostatic effects. XRD results show a composition-dependent balance between CNC-induced crystallinity and ε-PL-induced disruption of ordered domains, highlighting the importance of additive concentration in determining film structure. The biocomposite coatings were applied to fresh chilles and tested for 21 days under ambient storage conditions. The optimised formulation with 3 wt.% ε-PL reduced weight loss to 1.70 %, compared to 9.52 % for the control and 5.11 % for neat PVA. It also maintained visual quality and stiffness. The improved performance is attributable to the creation of a compact, well-integrated network structure that improves moisture barrier qualities while also providing bioactive functionality. This study establishes a clear structure property performance relationship and demonstrates the potential of PVA/CNC/ε-PL biocomposites as scalable, environmentally friendly coatings for post-harvest preservation and active food packaging applications.

PHOTOCATALYTIC PERFORMANCE OF TiO₂/ZNO COMPOSITES FOR EFFICIENT DEGRADATION OF METHYL ORANGE DYE: STRUCTURAL AND OPTICAL PROPERTIES

Hartini Ahmad Rafaie — 2026-06-08

Semiconductor-based photocatalysts, such as ZnO and TiO₂, are widely studied for the degradation of organic dyes in wastewater due to their stability and cost-effectiveness. However, ZnO alone suffers from rapid electron-hole recombination, limiting its photocatalytic performance, while TiO₂ is limited by UV-only activation. Herein, TiO₂/ZnO composites were synthesized with varying TiO₂ loadings (5 wt.%, 10 wt.%, and 15 wt.%) using an ultrasonic-assisted chemical mixing method. The structural, morphological, and optical properties were comprehensively characterized using scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR), and photoluminescence spectroscopy (PL). SEM showed that the 10 wt.% TiO₂/ZnO composite exhibited the most uniform dispersion and porous morphology. FTIR confirmed Ti–O–Zn bond formation, while PL spectra indicated that 10 wt.% TiO₂ incorporation achieved the lowest emission intensity, signifying reduced recombination. Photocatalytic degradation of methyl orange (5 mg/L) under UV irradiation (6 Watt, λ = 325 nm) demonstrated that the 10 wt.% TiO₂/ZnO composite achieved the highest efficiency (89.2 %) with a rate constant, k of 0.02106 min⁻¹, surpassing pure ZnO (82.6 %) and pure TiO₂ (74.4 %). In contrast, 15 wt.% TiO₂/ZnO composite caused agglomeration and increased recombination, lowering activity. These results confirm that optimization of TiO₂ loading enhances heterojunction formation, promotes charge separation, and, consequently, enhances photocatalytic efficiency. The findings indicate that TiO₂/ZnO composites with controlled composition hold great potential for sustainable wastewater treatment.

INFLUENCE IN SOLVENT COMPOSITION ON MICROSTRUCTURAL INTEGRITY AND FATIGUE RESISTANCE OF PRINTED GNP/Ag CONDUCTIVE INKS

Zikriah Zakaria — 2026-06-08

Conductive inks are essential for flexible and wearable electronics, however their mechanical durability under torsional fatigue remains poorly understood. This study investigated the formulation and mechanical behaviour of hybrid graphene nanoplatelet and silver conductive inks to address this gap. Three ink formulations were developed using fixed ratios of graphene nanoplatelets at 0.5 g, silver flakes at 4.292 g, and silver acetate at 0.42 g, with varying butanol-to-terpineol solvent ratios of 5:10, 10:10 and 15:10 corresponding to samples labelled as 5-B, 10-B and 15-B respectively to influence viscosity and filler dispersion. The inks were screen-printed onto copper substrates and thermally cured at 250 °C for five hours. Cyclic torsional fatigue testing, conducted up to 16,000 cycles at an angle of 90 degrees and speed of 211 cycles per minute to assess resistance stability under repeated mechanical stress. The results revealed that solvent composition played an important role in determining the mechanical and electrical performance of the printed inks. The 10-B sample with a 10:10 butanol-to-terpineol drops improved filler network formation, leading to enhanced conductivity and structural cohesion. Scanning electron microscopy (SEM) at ×800 and ×2000 magnifications identified microstructural failure modes such as cracking, filler agglomeration, and void formation, with more severe degradation observed in formulations in the 5-B sample. Among the tested samples formulations of 5-B, 10-B and 15-B, the optimised 10-B formulation exhibited an excellent resistance stability with initial resistance of 0.325 ohms and after 16,000 cycles, which increased to 0.520 ohms with minimal physical deterioration, confirming its superior fatigue endurance. This work highlights the importance of solvent-engineered rheology and filler interaction in achieving mechanically robust and electrically stable conductive inks.

SURFACE MORPHOLOGY, COMPOSITIONS, CRYSTALLINITY, AND THERMAL STABILITY OF MICROCRYSTALLINE CELLULOSE DERIVED FROM DENDROCALAMUS ASPER BAMBOO FIBER

Muhammad Aqil Asyraaf Mohd Mahadi — 2026-06-08

Microcrystalline cellulose (MCC) is a widely applied material in pharmaceutical, food and composites due to its biocompatibility, renewability and desired properties. Nevertheless, the conventional process for preparing MCC is wood or cotton cellulose based using alkaline and bleaching process which may not be sustainable in terms of resource depletion, deforestation, and environmental stability. Finding a renewable, sustainable source of MCC can help reverse this trend and encourage more eco-friendly manufacturing processes. Bamboo, especially fast-growing species such as Dendrocalamus asper (D. asper), provides an environmentally sound source with rich cellulose resources and is one of the promising raw materials for green preparation of MCC. Therefore, the present work is to prepare MCC from D. asper fiber and investigate its physicochemical characteristics. The MCC was prepared using alkali treatment of bamboo with NaOH, followed by acidified bleaching using NaClO₂ and HNO₃ and finally acid hydrolysis with H₂SO₄. Then, the MCC was taken for further characterizations using scanning electron microscope (SEM) equipped with energy dispersive x-ray (EDX), fourier transform infrared spectrophotometer (FTIR), x-ray diffractometer (XRD), as well as thermogravimetric analysis (TGA) to investigate its surface morphologies, elemental composition, functional groups, crystallinity and thermal stability. The recovered MCC has rod-like structures and contains 43 % of carbon and 57 % of oxygen. The FTIR spectrum obtained is consistent with other MCC sources. The crystallinity index calculated for the MCC is 58 %. The MCC reveals initial weight loss and is thermally stable as temperature increases to 500 ºC. DTG analysis confirms MCC has thermal stability around 180-210 ºC. The MCC extracted using bamboo fiber offers different properties compared to MCC extracted using wood or cotton fibers, offering new opportunities for green industry development that aligns with the United Nations’ Sustainable Development Goals (SDG).

NANOCRYSTALLINE Bi₂Te₃ VIA MECHANICAL ALLOYING: EFFECTS OF MILLING SPEED, PROCESS CONTROL AGENTS AND THERMOELECTRIC PERFORMANCE

Nurkhaizan Zulkepli — 2026-06-08

Nanostructured thermoelectric materials have attracted considerable attention as a pathway to enhance device efficiency by reducing lattice thermal conductivity while maintaining favorable electrical transport. In this work, nanocrystalline Bi₂Te₃ was synthesized through mechanical alloying, with systematic evaluation of the effects of milling speed and the introduction of ethanol as a process control agent. Particle size analysis revealed that higher milling speeds promoted significant refinement, with optimal conditions achieved at 600 rpm, though further increases resulted in diminished efficiency due to particle agglomeration and heat generation within the milling vial. The incorporation of ethanol effectively reduced cold welding and particle clustering, yielding finer distributions; however, this came at the expense of powder yield, underscoring the trade-off between structural control and processing efficiency. Microstructural characterization using FESEM confirmed the transformation of bulk Bi₂Te₃ into nanograins with sizes approaching the sub-micron range, accompanied by agglomerated morphologies. Thermal conductivity measurements demonstrated a pronounced reduction for the milled samples compared with unmilled counterparts, a consequence of enhanced phonon scattering at grain boundaries. Importantly, electrical transport properties remained largely preserved, leading to an overall improvement in the thermoelectric figure of merit (ZT). These findings establish mechanical alloying as a cost-effective and scalable strategy to optimize Bi₂Te₃ for thermoelectric applications, particularly in waste heat recovery, low-temperature cooling, and portable energy systems, where efficiency, manufacturability, and scalability are critical.

EFFECT OF FERRIHYDRITE-CHITOSAN NANOCOMPOSITES PRECURSOR RATIO ON PALM OIL MILL EFFLUENT PRE-TREATMENT

Juliana Jumadi — 2026-06-08

Statistically, it has been estimated that more than 0.50 tonnes of palm oil mill effluent (POME) will be generated for each tonne of fresh fruit bunches (FFBs) production. Fresh POME normally possesses a high amount of total solid, biochemical oxygen demand (BOD), chemical oxygen demand (COD), oil and grease (O&G). Therefore, POME treatment has received great attention from environmental scientists. In this study, ferrihydrite-chitosan (FC) nanocomposites were prepared using a simple co-precipitation method by varying the ratio of ferrihydrite and chitosan. The influence of precursor ratios (1:1, 2:1 and 1:2 w/w) of FC nanocomposites on palm oil mill effluent pre-treatment was investigated in flocculation studies at optimum experimental conditions. The characteristics of FC nanocomposites, before and after POME treatment were studied using Fourier transform infrared (FTIR) spectrometer, energy dispersive X-ray (EDX) spectrometer and optical polarising microscope (OPM) analyses. The results indicate that the 1:1 w/w FC nanocomposite exhibited the highest percentage of contaminant reduction at 82.63 %, 75.70 %, 74.07 % and 49.08 % for total suspended solids (TSS), turbidity, COD, and O&G removal, respectively. The synergistic effects between ferrihydrite and chitosan precursors highlight the potential of the FC nanocomposites as promising flocculants for POME. Overall, this research is relevant to POME management and treatment, particularly in Indonesia and Malaysia the two major palm oil producers in the world. Moreover, research findings support the sixth Sustainable Development Goal of the United Nations, namely Clean Water and Sanitation.

ENHANCED PHOTODEGRADATION OF METHYL ORANGE VIA TiO₂/g-C₃N₄ PHOTOCATALYST UNDER LOW-INTENSITY UVC IRRADIATION

Muhammad Aqil Asyraaf Mohd Mahadi — 2026-06-08

Synthetic anionic azo dyes, such as methyl orange (MO), represent substantial environmental issues because of their persistence and toxicity in water ecosystems. The presence of this dye in water bodies tends to pose significant risks to human health and the ecological systems under long-term exposure. Previous research has shown that the synergistic heterojunction formation between TiO₂ and g-C₃N₄ may reduce electron-hole recombination rate and enable the material to absorb more light, due to its extended absorption range, hence, significantly improving photoactivity. Thus, in the present work, TiO₂/g-C₃N₄ composite photocatalysts were prepared via a facile mixing procedure, with varying g-C₃N₄ ratios. The photodegradation performance was evaluated against the MO dye under a very low UVC light intensity (9 W). The surface morphology, composition, functional groups, recombination behaviours and band gap energy were characterised using SEM-EDX, FTIR, PL and UV-Vis-NIR, respectively. The fabrication of TiO₂/g-C₃N₄ composites has resulted in a significant enhancement in the photodegradation performance of pure TiO₂and g-C₃N₄. The TiO₂/g-C₃N₄ with a ratio of 0.5:0.15 (TG2) demonstrated a rapid removal efficiency (~72 %) within 180 min under normal conditions, which was 1.4 times higher than that of pure TiO₂. The enhanced photoactivities were attributed to the outstanding separation of charge carriers (e_CB^-/h_VB⁺) as demonstrated by the band gap and photoluminescence spectra studies. The kinetic display pseudo-first-order kinetics with a rate constant of 7.3 × 10^-3 min^-1. This work revealed that the TiO₂/g-C₃N₄ composite photocatalysts exhibit promising potential for degrading dye molecules via the heterojunction mechanism.

SUSTAINABLE PRODUCTION of AgO:FeO NANOCOMPOSITES: STRUCTURAL, OPTICAL, AND ANTIMICROBIAL ANALYSIS

Mohammed Zorah — 2026-06-08

The green synthesis of metal oxide nanoparticles has attracted considerable interest owing to its eco-friendly, cost-effective, and sustainable nature. Silver oxide (AgO) and iron oxide (FeO) nanoparticles exhibit good antibacterial and optical properties and their coalescence into nanocomposites may enhance biological activity through synergistic effects. This work contains the green synthesis and characterization of silver oxide/iron oxide (AgO:FeO) nanocomposites by a green chemistry strategy. The structural, morphological, elemental compositional and optical properties were investigated using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersive x-ray (EDX), Fourier transform infrared spectroscopy (FTIR), and UV-visible spectroscopy. Analysis with XRD patterns revealed that pure crystalline AgO and FeO phases had formed without any detectable impurities. Nanoparticles showed mild agglomeration with average diameter ca 164 nm in FESEM imaging. The FTIR spectra analyses gave evidence of bio-organic functional groups originating from the plant extract, in addition to metal–oxygen bonds that signifying successful green synthesis route. Characteristic surface plasmon resonance that confirmed the formation of nanocomposite was seen from UV–visible spectroscopy. The antibacterial activity of the AgO:FeO nanocomposites was evaluated by mean of the agar well diffusion method against a broad spectrum of pathogenic microorganisms, such as Gram-positive bacteria (Staphylococcus aureus (S. aureus), Staphylococcus epidermidis (S. epidermidis)), Gram-negative bacteria (Escherichia coli (E. coli) and Klebsiella species)). The nanocomposites exhibited significant antibacterial activity with the largest inhibition (23.67 mm) against S. epidermidis. The AgO: FeO nanocomposite showed synergistic antibacterial properties which were comparable with, or even greater than those of the individual AgO and FeO nanoparticles. This improvement is mainly due to high surface and enhanced ROS production. These findings highlight the potential of AgO:FeO nanocomposites synthesized through a biosynthesized green chemistry process as effective antimicrobial agents for medicinal applications.

INFLUENCE OF ZnO INCORPORATION ON PHASE STABILITY, MORPHOLOGY AND APPARENT DENSITY OF TiO₂-BASED SPRAY FEEDSTOCK POWDERS

Muhamad Akmal Mohd Sani — 2026-06-08

TiO₂ based ceramic coatings are extensively used in plasma spray applications due to their excellent hardness, wear resistance, and chemical stability. Nevertheless, the performance of plasma sprayed coatings is strongly influenced by the physical and microstructural characteristics of the feedstock powders. This study investigates the influence of ZnO incorporation on the phase composition, morphology, microstructure, particle distribution, and apparent density of TiO₂-based plasma spray feedstock powders. ZnO was selected due to its favourable chemical compatibility and complementary physical properties with TiO₂, which may enhance phase stability, particle cohesion, and powder packing behaviour. TiO₂ and ZnO powders were blended at different weight ratios of 90 wt.% TiO₂/10 wt.% ZnO, 80 wt.% TiO₂/20 wt.% ZnO, and 70 wt.% TiO₂/30 wt.% ZnO using wet mixing followed by planetary ball milling without milling balls to promote homogeneous agglomeration while preserving particle integrity. X-ray diffraction (XRD) analysis confirmed the coexistence of anatase and rutile TiO₂ phases together with the ZnO wurtzite phase without the formation of secondary phases, indicating good phase compatibility and homogeneous ZnO distribution within the powder matrix. FESEM observations revealed angular and well-defined TiO₂ particles, while ZnO appeared as finer irregular aggregates distributed around the TiO₂ surfaces. Incorporation of 10 wt.% ZnO resulted in more uniform particle dispersion, reduced agglomeration, and improved packing through effective filling of interparticle voids. Apparent density analysis showed that moderate ZnO incorporation enhanced bulk density and packing efficiency, whereas excessive ZnO addition increased interparticle voids and reduced powder density. Among all compositions, the 90 wt.% TiO₂/10 wt.% ZnO feedstock exhibited the most balanced combination of phase stability, morphology, and packing characteristics, demonstrating strong potential for dense and wear-resistant plasma-sprayed coating applications.

COMPARATIVE ASSESSMENT OF PASSIVE AND PERSONAL SAMPLING FOR AIRBORNE MICROPLASTICS IN A PLASTIC MANUFACTURING FACILITY

Dewika Munisamy — 2026-06-08

The presence of microplastics (MPs) in indoor air has emerged as a pressing occupational health concern, particularly in plastic manufacturing environments, where airborne exposure is elevated due to direct handling and processing of polymeric materials. This study presents a cross-sectional assessment of inhalable MPs within a plastic manufacturing facility in the Klang Valley, Malaysia, using both passive and personal air sampling techniques. Samples were analyzed for particle size, shape, and color using a stereomicroscope statistically evaluated using chi-square tests to determine associations between these characteristics and sampling methods. The results revealed a clear dominance of fibrous, small-sized (<500 µm), and transparent MPs, with passive sampling consistently capturing 2.74 times higher counts than personal sampling. Transparent and black particles were most associated with fibers and smaller sizes, suggesting enhanced airborne mobility and prolonged suspension. Statistically significant associations (p < 0.05) were observed across all variable pairings. Micro-Raman spectroscopy confirmed the presence of polyethylene in the samples collected. These findings highlight the importance of targeted mitigation strategies, including engineering controls, personal protective equipment (PPE) usage, and environmental monitoring, to reduce occupational exposure and potential respiratory health risks. This study provides critical empirical data to support policy development and workplace safety interventions in the plastic manufacturing sector, particularly in developing regions.

COPPER LOADED MAGNETIC HYDROCHAR DERIVED FROM COCONUT HUSK FOR CATALYTIC REDUCTION OF 4-NITROPHENOL

Tengku Shafazila Tengku Saharuddin — 2026-06-08

4-nitrophenol (4-NP) is a hazardous pollutant that poses significant risks to human health and the environment. One promising approach to address this contaminant is the use of hydrochar derived from biomass sources. In this study, hydrochar was produced through hydrothermal carbonisation of coconut husks. The synthesised hydrochar was then integrated with magnetite and further loaded with Cu to form Cu magnetic hydrochar (Cu-MHC). The properties and catalytic performance of the Cu-MHC were examined by synthesising with varying copper loadings (1 %, 5 %, and 10 %). Various factors influencing the degradation of 4-NP into 4-aminophenol (4-AP) using sodium borohydride (NaBH₄) as the reducing agent were investigated, including the effects of copper loading, catalyst dosage, and the initial concentrations of 4-NP. The catalytic performance was compared across different copper loadings against that without copper (MHC) and showed that MHC achieved 13.25 %, while 1 % Cu-MHC reached 15.38 % in 3 minutes. A significant improvement was observed at 5 % Cu-MHC with 95.92 %, followed by 10 % Cu-MHC at 92.62 % in 3 minutes. From the results, 5 % Cu-MHC is the most effective catalyst for the reduction of 4-NP and was further characterized using x-ray diffraction (XRD), field emission scanning electron microscope with energy dispersive x-ray spectroscopy (FESEM-EDX) and transmission electron microscope (TEM). The results showed that 30 mg of 5 % Cu-MHC could effectively degrade 0.12 mM 4-NP (98 %) within 3 minutes. TEM analysis revealed predominantly spherical nanoparticles with diameters between 15 and 20 nm, highly distributed across the hydrochar. FESEM-EDX mapping confirmed the presence of copper and describe well distribution of copper on the surface of magnetic hydrochar nanocomposite. This is further supported by the absence of Cu peaks in the XRD spectra, which may indicate a high dispersion of copper species on the magnetite hydrochar, which contributes to the efficient catalytic reduction of 4-NP.

IMPACT OF CALCINATION TEMPERATURE ON STRONTIUM CARBONATE FORMATION AND MICROSTRUCTURAL–THERMAL PROPERTIES OF SAMARIUM STRONTIUM COBALT OXIDE–SAMARIUM-DOPED CERIA CARBONATE COMPOSITE CATHODES FOR LOW-TEMPERATURE SOLID OXIDE FUEL CELLS

Siti Ameerah Nadiah Jamal — 2026-06-08

Solid oxide fuel cells (SOFCs) operating at low temperatures require cathodes with tailored microstructural and thermal properties to address performance challenges. The formation of SrCO₃ during the calcination process significantly influences the properties of the SSC–SDCC composite cathode for LT–SOFCs. This study systematically investigates the effect of calcination temperature (600 – 750 °C) on SrCO₃ formation and its correlation with the microstructural and thermal properties of SSC–SDCC (60:40 wt.%) composite cathodes. The cathode powders were mixed through the high–energy ball milling (HEBM) method and calcined at four different temperatures (600, 650, 700, and 750 °C). The pellet cathodes were fabricated using the uniaxial pressing method and sintered at 600 °C. Comprehensive characterizations using XRD revealed that calcination temperatures ≥700 °C effectively minimized SrCO₃ formation while maintaining phase purity. FESEM analysis revealed that all samples exhibited particle agglomeration, consistent with calcination powder theory, where particle bonding intensifies with increasing temperature. Porosity analysis reveals optimal cathode functionality with measured values of 35.91 – 38.78 %, residing within the established 20 – 40 % target range for effective gas diffusion while maintaining structural stability. The thermal expansion coefficients (15.1 – 16.00 × 10⁻⁶ K⁻¹) align well with ceria electrolytes (11.1 × 10⁻⁶ K⁻¹), exhibiting comparable thermal behavior while retaining beneficial SrCO₃ phases that enable functional compatibility. This systematic variation provides valuable insights for interface engineering in real–world SOFC operating conditions for the development of efficient and durable LT–SOFC systems for clean energy applications.

COMPARATIVE HALF-CELL ANALYSIS OF SULFUR-, NITROGEN-, AND FLUORINE-DOPED REDUCED GRAPHENE OXIDE ANODES

Mohamad Taufiq Mohamad Alias — 2026-06-08

Advanced lithium iron phosphate battery systems demand anode materials with higher capacity, better rate capability, and stronger structural stability than conventional graphite. This study investigates the electrochemical performance of functionalized reduced graphene oxide (rGO) as a potential anode material, focusing on sulfur (S), nitrogen (N), and fluorine (F) heteroatom doping. The materials were synthesized through controlled hydrothermal and thermal treatment methods and characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray (EDX) spectroscopy. Structural analysis showed that sulfur doping increased interlayer spacing and introduced more active defect sites, while nitrogen and fluorine doping enhanced graphitic alignment, as indicated by a sharper (002) peak near 26°, which corresponds to reduced interlayer spacing. Electrochemical properties were evaluated using cyclic voltammetry (CV) within a potential range of 0.01–3.0 V (vs. Li/Li⁺). Among all samples, sulfur-doped rGO exhibited the strongest electrochemical performance, with the largest CV curve area and an apparent capacitance of 492.32 F g⁻¹, corresponding to a specific capacity of 408.90 mAh g⁻¹. Pristine rGO achieved 417.66 F g⁻¹ (346.89 mAh g⁻¹), whereas nitrogen-doped and fluorine-doped samples showed lower values of 278.39 F g⁻¹ (231.21 mAh g⁻¹) and 223.07 F g⁻¹ (185.27 mAh g⁻¹), respectively. The results indicate that charge storage is mainly governed by pseudocapacitive surface reactions rather than bulk intercalation. Overall, sulfur-doped rGO demonstrated superior charge storage capability, highlighting its potential as an advanced anode material for next-generation LiFePO₄-based lithium-ion batteries.

EFFECT OF HYDROXYAPATITE FILLER SIZE ON HIGH STRESS FATIGUE LIFE OF SELF-REINFORCED POLYLACTIC ACID COMPOSITES

Zaleha Mustafa — 2026-06-08

In this study, the fatigue behaviour of self-reinforced polylactic acid (sr-PLA) biomaterials at high stress levels was investigated, and the influence of different filler sizes (2.99 μm and 20 nm) was evaluated using Weibull distribution analysis to assess their potential for bone fixation applications. The composite was produced by drawing PLA fibres in a PLA matrix containing hydroxyapatite (HA) particles of micrometre and
nanometre-sized particles to produce HA/PLA/PLA prepreg. The pre-impregnated sheets were then compression moulded and tested under quasi-static bending and flexural fatigue at an 80 % stress level, 2 Hz until failure. The addition of the filler enhances the bending properties of the composite. At the same time, the bending strength and modulus increase with a decrease in the filler size. Under the specific cyclic loading conditions tested, the initial data indicate that the Weibull median fatigue life of sr-PLA reduces with the presence of the fillers. However, the fatigue resistance of the HA-filled composite improved with a smaller filler size. The Weibull median fatigue life of HA/sr-PLA increases from 104,514 cycles to 254,884 cycles for μm-HA/PLA/PLA and nm-HA/PLA/PLA composites, respectively. The Weibull statistical model indicates that the scale parameters improve by 140 % when smaller filler particles (nm-HA) are used. During fatigue testing, the modulus of the composite decreased due to material damage. SEM analysis indicated that failure at the HA/matrix interface was a major contributing factor. Furthermore, fracture behaviour suggests that the materials are more susceptible to tensile stress, which may be attributed to limited bonding at the HA/matrix interface.

UTILIZATION OF NATURAL SILICA FROM RICE HUSK ASH TO IMPROVE ELECTRICAL CONDUCTIVITY OF SDC-BASED IT-SOFC ELECTROLYTE

Zolhafizi Jaidi — 2026-06-08

Solid oxide fuel cells (SOFCs) rely on electrolytes with high ionic conductivity and thermal stability, especially for intermediate-temperature operations (500–700 °C). Yttria-stabilized zirconia (YSZ), the conventional SOFC electrolyte, requires high operating temperatures, which leads to thermal mismatch, interfacial degradation, and other performance issues. Samarium-doped ceria (SDC) is a promising alternative due to its superior ionic conductivity at lower temperatures. However, SDC still faces challenges in achieving full densification and minimal porosity without elevated sintering temperatures. This study explores the incorporation of natural silica derived from rice husk ash (RHASiO₂) as an eco-friendly sintering aid to enhance the structural and electrochemical performance of SDC electrolytes. RHASiO₂ was calcined at 700 °C and combined with commercial SDC powder in various weight percentages (0 %–3 %) using dry ball milling. The mixtures were uniaxially pressed into pellets and sintered at 1200 °C. Thermogravimetric analysis (TGA) showed that RHASiO₂ improved thermal stability by reducing weight loss during intermediate and final degradation phases. The microstructure and morphology were characterized using scanning electron microscopy (SEM), while porosity was quantified through image analysis using ImageJ software. The results revealed a decreasing trend in porosity with increasing RHASiO₂ content, reaching the lowest value of 4.58 % in the SDC3.0 sample. Electrochemical impedance spectroscopy (EIS) demonstrated enhanced conductivity and reduced grain boundary resistance for RHASiO₂-modified samples. The highest total ionic conductivity, 2.76 x 10^-2 S·cm⁻¹ at 700 °C, was achieved by SDC3.0, which also exhibited the lowest activation energy of 0.768 eV. These results confirm that RHASiO₂ effectively promotes densification and enhances the electrical conductivity of SDC electrolytes, offering a sustainable and low-cost route to improve SOFC performance.

EFFECTS OF SINTERING TEMPERATURE ON THE MICROSTRUCTURES AND ADHESION STRENGTH OF SLURRY SPRAYED YSZ/NiCoCrAlYTa FUNCTIONALLY GRADED-THERMAL BARRIER COATING ON INCONEL 625

Fadzlun Nadrah Mohd Sharuddin — 2026-06-08

Thermal barrier coating (TBC) has been widely used in protecting turbine components exposed to extreme temperature conditions. The conventional TBC system comprises of a metallic bond coat layer deposited on the substrate and yttria stabilized zirconia (YSZ) top layer. However, the thermal expansion mismatch between the bond coat and top coat layer has become a problem that leads to coating delamination. To mitigate this issue, the functionally graded-thermal barrier coating (FG-TBC) method is adopted, where a homogenous coating structure consists of composite materials layered on the substrate by gradually changing the compositional ratios over the coating thickness. This smooth transition from the substrate to the top layer minimizes the thermal expansion mismatch between the coating layers, reduces the internal residual stresses, and increases the bonding strength. On the other hand, plasma spray has been the commonly used method for depositing TBC. However, in this study, YSZ/NiCoCrAlYTa FG-TBC was fabricated by using the slurry spray technique (SST), considering the lower cost and simplicity of the method. In determining the optimum sintering temperature, effects of various sintering temperatures (i.e., 950, 1000, 1050, 1100, and 1150 ℃) on the microstructures and adhesion strength were investigated. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were applied to characterize the microstructures, and a pull-off adhesion test was conducted to measure the adhesion strength between the coating layers and the substrate. The findings showed that samples sintered at 1100 ℃ revealed dense FG-TBC layers with a continuous reaction layer at the substrate interface, minimal porosity, and no presence of cracks, with the highest adhesion strength, which is 22.87 MPa. Therefore, the effective sintering temperature for slurry-sprayed YSZ/NiCoCrAlYTa FG-TBC was considerably achieved at 1100 ℃.

PHYSICOCHEMICAL AND SURFACE CHARACTERIZATION OF GLUTARALDEHYDE-CROSSLINKED FISH GELATIN/CHITOSAN BIOFILMS FOR WOUND DRESSING APPLICATIONS

Noor Athirah Aida Noor Rizan — 2026-06-08

This work focuses on the fabrication of wound healing materials from natural fish gelatin and a bio-based polymer chitosan. The main aim was to develop a biocompatible film with excellent physicochemical properties as protective layers for effective wound healing treatments. In this work, fish gelatin was selected for its low immunogenicity and film-forming ability, while chitosan enabled to improve surface wettability and biocompatibility. The fish gelatin/chitosan biofilms were prepared using the solution casting method with different chitosan and black tilapia fish skin gelatin ratios (FC-100:0, FC-95:5, and FC-80:20) and subsequently crosslinked with 0.6 mL glutaraldehyde (0.25 % v/v working concentration) to enhancing the structural stability without inducing brittleness. All prepared samples were analysed using Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM) and contact angle measurement via goniometer. FTIR analysis, it was indicated strong molecular interactions between gelatin and chitosan through O–H and N–H stretching bands. Surface roughness analysis by AFM showed that FC-95:5 produced the most uniform surface morphology (Ra = 2.479 nm, Rq = 3.530 nm), while FC-80:20 exhibited the highest surface roughness (Ra = 11.943 nm, Rq = 16.928 nm). In addition, contact angle measurements confirmed hydrophilic surface wettability across all formulations, with FC-80:20 recording the lowest average contact angle of 65.9 °, indicating the greatest water affinity among the samples. In conclusion, the fish gelatin/chitosan biofilms exhibited the most promising physicochemical and surface characteristicsas a natural and sustainable foundation for potential wound dressing applications.

EFFECT OF PULSE FREQUENCY ON MICROSTRUCTURE AND TRIBOLOGICAL PROPERTIES OF TiC NANOCOMPOSITE COATINGS ON ASTM A240 STAINLESS STEEL VIA TIG TORCH MELTING

Alin Qistina Shamsuri — 2026-06-08

ASTM A240 duplex stainless steels offer improved mechanical properties and better corrosion performance, making them widely used in industries such as oil and gas, chemical processing, marine, and structural applications. Despite its high strength and corrosion resistance, the industrial application of the substrate is limited by low surface hardness and wear resistance. To overcome these issues, TiC nanoparticles were melted using TIG torch method at a constant current of 140 A and three different pulse frequencies (15, 20, and 25 PPS) to produce TiC nanocomposite coatings. Therefore, this study investigates the influence of pulse frequency on the surface reinforcement of ASTM A240 grade S31803 using TiC nanoparticles deposition via the Tungsten Inert Gas (TIG) torch method. The microstructural features, coating thickness, and phase structure were investigated via digital microscope, Field Emission Scanning Electron Microscopy (FESEM) and X-ray Diffraction (XRD) analysis, while the mechanical properties were determined using Micro-Vickers hardness and linear reciprocating wear testing techniques. As observed, an increase in pulse frequency considerably improves microstructures and tribological properties. Among all the samples, a pulse frequency of 25 PPS showed superior behaviour with a coating thickness of 1.78 mm and maximum microhardness of 415.96 HV due to formation of CrTi and CrC intermetallic phases. Additionally, lowest coefficient of friction (CoF) of 0.08 was attained with minimal surface ploughing for TiC nanocomposite coating.

EFFECT OF SURFACE LASER SHOCK PEENING ON THE TENSILE PROPERTIES AND HARDNESS OF SELECTIVE LASER MELTED (SLMed) A357 ALLOY

Ignatius Uyabemem Agbaye — 2026-06-08

Selective laser melting (SLM) has been widely used to fabricate Al-Si-Mg alloys, which are extensively used in the automotive, aerospace, and biomedical industries. However, due to its rapid solidification and cooling rates, the process induces thermal fluctuations that lead to residual stresses in the parts, necessitating stress-relief post-processing. This study examines the influence of surface laser shock peening (LSP) on the residual stress profile, microstructure, hardness and tensile properties of A357 alloy fabricated by SLM. LSP treatment was done using controlled laser parameters and dimple spacing. X-ray diffraction analysis shows that compressive residual stresses up to -57 MPa were produced, which modified the tensile residual stresses (TRS). Variable pressure scanning electron microscopy (VP-SEM) revealed remarkable grain refinement and a uniform distribution of primary α-Al and fibrous Si phases after LSP, which is attributed to LSP-induced plastic deformation and a high dislocation density. This produced an improvement of about 18.6 % in hardness. Mechanical tests recorded improvement in strength, as yield strength (YS) increased from 87±0.87 to 155±1.32 MPa, about 78 % increase, while ultimate tensile strength (UTS) increased from 197±1.0 MPa to 263±3.61 MPa, representing 33.4 % increase at the bottom of the sample. At the sample top, YS increased from 95±1.0 MPa to 171±2.65 MPa, a 80 % increase, while the UTS increased from 200±2.65 MPa to 269±2.65 MPa, representing 34.5 % increase. However, elongation decreased slightly due to strain hardening. Analysis of fractured surfaces reveals reduced porosity and defect closure in the LSP-treated samples, which inhibited crack initiation and propagation. This confirms that LSP is an effective strategy for mitigating residual stresses and improving the mechanical performance of the A357 alloy, making it appropriate for critical structural applications.

INFLUENCE OF ELECTRODEPOSITION POTENTIAL ON COBALT(II) NITRATE-DOPED POLY(3,4-ETHYLENEDIOXYTHIOPHENE) SURFACE PROPERTIES FOR SENSING APPLICATIONS

Nursyamimi Nayli Mohd Shahri — 2026-06-08

Fabrication of cobalt (II) nitrate-doped poly (3,4-ethylenedioxythiophene) (Co-PEDOT) on SPCE via electrochemical deposition is necessary to enhance the sensitivity of the modified electrode for sensing applications. The 3,4-ethylenedioxythiophene (EDOT) monomer was prepared in aqueous solution with sodium dodecyl sulfate (SDS) and cobalt (II) nitrate to improve its dispersion and solubility in water. Electrochemical deposition of Co-PEDOT was carried out using cyclic voltammetry (CV), where the applied potential induces oxidation of EDOT into radical cations, leading to polymerization and PEDOT formation. In this study, the effect of CV upper potential limits (+1.0 to +2.0 V) on Co-PEDOT surface properties, overoxidation behaviour, and electrochemical performance toward the [Fe(CN)₆]³⁻/[Fe(CN)₆]⁴⁻ redox system was investigated. The formation of PEDOT was confirmed by Raman spectroscopy through characteristic bands. The spectra also suggested that the doped Co appeared as cobalt (II) oxide (CoO), although several CoO peaks could not be conclusively identified due to overlapping with PEDOT peaks. Morphologically, all films exhibited a cauliflower-like structure, confirming successful Co-PEDOT growth on SPCE. Increasing the upper potential from +1.0 to +1.2 V promoted PEDOT formation, as evidenced by the highest sulfur content and branch-like structures. At +1.6 V, these structures fragmented into leaf-like features due to overoxidation, and they disappeared at +2.0 V, consistent with reduced sulfur content and surface roughness. This is further supported by the decreased C=C stretching of thiophene rings at +1.6 V, indicating onset of overoxidation, while presence of sulfone (SO₂) bands at +2.0 V confirming further degradation. The film prepared at +1.2 V, prior to overoxidation, exhibited the roughest surface and highest redox activity toward the [Fe(CN)₆]³⁻/[Fe(CN)₆]⁴⁻ probe. These findings demonstrate that applied potential plays a critical role in tuning Co-PEDOT properties and optimizing sensor performance.

CHEMICALLY ACTIVATED SUNFLOWER SEED SHELL BASED ACTIVATED CARBON FOR ALLOPURINOL REMOVAL: ISOTHERM, KINETICS AND REGENERATION STUDIES

Mohd Raziff Mat Hasan — 2026-06-08

Allopurinol (ALP) is an emerging contaminant that enters aquatic environments due to incomplete removal in wastewater treatment plants. Its major metabolite, oxypurinol, can form riboside adducts through the purine metabolism pathway, potentially disrupting purine metabolism in aquatic organisms. This study aims to synthesize and evaluate sunflower seed shell-derived activated carbon (SSSAC) for the adsorption of ALP from aqueous solutions. The SSSAC was produced through chemical activation using potassium hydroxide (KOH). Scanning electron microscopy (SEM) revealed that the raw sunflower seed shells exhibited a dense and non-porous morphology, whereas the SSSAC displayed a well-developed porous texture. The zeta potential of the precursor was −33.00 mV, which decreased to −51.30 mV after KOH activation, indicating enhanced surface negativity. In batch adsorption studies, increasing the initial ALP concentration from 10 to 100 mg/L resulted in a rise in adsorption capacity from 9.11 to 74.37 mg/g, while the percentage removal declined from 91.10 % to 74.37 % at higher concentrations. The optimum pH for ALP adsorption was pH 5, achieving a maximum capacity of 87.54 mg/g. Isotherm study revealed that the Freundlich model best represented the adsorption behaviour, with the lowest root mean square error (RMSE) of 1.15 mg/g and an average error of 5.52 %, signifying a multilayer adsorption process. The Langmuir model predicted a maximum monolayer capacity (Qₘ) of 113.84 mg/g. Kinetic analysis confirmed that adsorption followed the pseudo-first-order (PFO) model. Regeneration studies showed that SSSAC remained reusable up to five cycles, after which the ALP uptake declined to 34.53 mg/g and the adsorbent yield decreased to 50.24 %. These findings demonstrate that SSSAC is a promising low-cost adsorbent for the effective removal of ALP from contaminated water systems.

ELECTROCHEMICAL PERFORMANCE OF ANTIMONY-MODIFIED POROUS LAMELLAR ZINC ALLOY ANODE IN ALKALINE AQUEOUS ELECTROLYTE

Muhammad Afiq Irfan Mohd Shumiri — 2026-06-08

Metallic zinc is one of the most attractive anode materials for post‑lithium batteries due to its natural abundance, safety, low cost and high theoretical capacity. However, it often suffers from severe polarization and poor reversibility, which hinder the practical application in aqueous alkaline rechargeable zinc‑ion batteries. Herein, this work presents antimony-modified porous lamellar zinc anode (Sb-pZn) as a promising high-performance negative electrode. The porous structure was fabricated by chemical dealloying of eutectic Zn-Al alloy, in which the less noble Al component was selectively removed in sodium hydroxide (NaOH) solution. This process produces a well-defined lamellar pattern with aligned porous channels, providing high surface area that facilitates efficient ion transport and enhances electrochemical stability. Surface modification was performed through galvanic replacement reaction in antimony trichloride (SbCl₃) solution. This introduces Sb sites that promote uniform Zn nucleation. As a result, Sb-pZn anode with Zn lamellar thickness of ~2920 nm (Sb-pZn-2920) shows improved Zn deposition behavior, with an ultralow nucleation overpotential of 101.3 mV even at high current density of 0.2 mA/cm². Cyclic voltammetry shows better redox kinetics with stronger peak currents and reduced peak separation of 0.736 V, while electrochemical impedance spectroscopy confirms a notable decrease in charge transfer resistance from 4.238 Ω for bare Zn to 1.770 Ω for Sb-pZn-2920. The combined effects of Sb incorporation and the tailored porous structure effectively reduce polarization and enhance overall electrochemical performance. This study offers a simple and scalable strategy for developing high-performance Zn anodes and provides valuable insights for advancing next-generation aqueous Zn-based energy storage systems.

QUALITATIVE METHYLENE BLUE MICROSCOPIC COMPARISON OF TRITON X 100 AND SDS DECELLULARIZATION PROTOCOLS FOR CHANNA STRIATA SKIN

Terry Previo Avianto — 2026-06-08

Fish skin-derived extracellular matrix (ECM) has emerged as a promising biomaterial for chronic wound management and commercial grafts. Compared to mammalian xenografts, acellular fish skin demonstrates favourable clinical outcomes alongside a reduced risk of disease transmission and fewer cultural limitations. Channa striata (snakehead fish) skin, naturally rich in type I collagen, is an excellent candidate for developing these biopolymer dressings. Effective decellularization is critical to remove cellular material while preserving the underlying ECM architecture; however, common detergents like sodium dodecyl sulphate (SDS) and Triton X-100 impact ECM composition and mechanics differently. This exploratory study qualitatively compared three detergent-based decellularization protocols for C. striata skin: 1 % Triton X-100, 1 % SDS, and a combined 0.5 % Triton X-100/0.5 % SDS solution. Fresh skin was divided into matched pairs of treated and untreated groups, processed accordingly, and evaluated via methylene blue (MB) staining and bright-field microscopy. Untreated controls exhibited abundant MB-positive nuclei and dense background staining. Treatment with 1 % Triton X-100 reduced nuclear staining while largely preserving the fibrillar collagen network. Conversely, 1 % SDS produced the greatest reduction in visible nuclei but caused apparent swelling and structural disruption of the collagen architecture. The combined 0.5 % Triton/0.5 % SDS protocol achieved intermediate nuclear clearance while better maintaining collagen organization than SDS alone. These findings support MB microscopy as a rapid, qualitative screening tool for decellularization strategies. They also suggest that mixed, low-concentration Triton/SDS protocols best balance cell removal with ECM preservation in C. striata skin. Future quantitative DNA, glycosaminoglycan, and mechanical testing will be required to optimize this protocol for scaffold development in diabetic ulcer applications.

PHASE STABILITY AND OXIDATION MECHANISM DIVERGENCE IN Al₃₀Cr₁₅Ni₁₅Si₁₀Ti₃₀ HIGH-ENTROPY ALLOY AT 1000 °C

Mudassar Hussain — 2026-06-08

AlCrNiSiTi high-entropy alloys (HEAs) are promising candidates as next-generation competitors to Ni-based superalloys and refractory alloys, offering low density and notable phase stability for high-temperature applications. However, their oxidation performance at elevated temperatures showed limitations due to complex oxidation behaviour. This study investigates the phase stability and oxidation response of an as-cast Al₃₀Cr₁₅Ni ₁₅Si₁₀Ti₃₀ HEA at 1000 °C for 100 hours. A systematic characterisation and performance evaluation framework is adopted, encompassing X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), electron probe microanalysis (EPMA), X-ray photoelectron spectroscopy (XPS), and differential scanning calorimetry (DSC). Structural and elemental investigations revealed the formation of nonprotective multielement oxides. The oxide scale is dominated by rapid, extensive TiO₂formation, resulting in a porous, poorly adherent surface layer. Beneath this, a discontinuous Al₂O₃ sublayer forms with dispersed (NiCr)₂O₃ and SiO₂, but it fails to develop into a continuous protective scale. As a result, the alloy exhibits a relatively high total mass gain of 2.1 mg cm⁻², significantly higher than alloys capable of forming a continuous Al₂O₃ barrier (<1 mg cm⁻² under similar conditions). Oxidation kinetics exhibit a clear three-stage parabolic behaviour, with rate constants of , , and mg² cm⁻⁴ h⁻¹ for the early, intermediate, and late stages, respectively. A global parabolic rate constant of mg² cm⁻⁴ h⁻¹ reflects the overall diffusion-controlled oxidation process. However, DSC analysis up to 1400 °C confirms the absence of solid-state phase transformations, aside from the melting peaks of individual phases, thereby identifying the melting range of the alloy. The findings highlight pronounced phase stability but limited oxidation resistance, emphasising the need for compositional tuning for extreme-temperature applications.

OPTIMIZATION OF ANNEALING DURATION FOR ENHANCED MICROSTRUCTURE AND PROPERTIES IN A Zn-2.4Mn ALLOY

Kar Fei Chan — 2026-06-08

This study investigates the microstructural evolution and mechanical response of a Zn-2.4Mn alloy subjected to controlled heat treatments. The alloy was evaluated in as-cast, homogenised (390 °C), and annealed states (400 °C for 1-4 h) using optical microscopy, grain segmentation, Vickers hardness, tensile testing, and indentation cross-section analysis. The as-cast Zn-2.4Mn exhibited coarse dendritic grains with significant Mn segregation (grain area 5416.55 µm²) and poor mechanical properties: UTS of 28.33 MPa and elongation of
2.84 %. Homogenisation reduced chemical gradients but increased measured grain area to 6834.19 µm² due to dissolution of fine dendritic boundaries, while UTS improved to 102.06 MPa and elongation to 6.10 %. Recrystallisation initiated after 1 h of annealing (grain area 4684.46 µm²; UTS 103.38 MPa; elongation 4.38 %) and progressed to full refinement by 3 h, producing the minimum grain area of 3263.32 µm². Hardness increased from 53.12 HV (as-cast) to 73.13 HV at 3 h, while tensile performance reached its optimum (UTS 152.92 MPa, elongation 7.31 %). Indentation analysis confirmed the 3 h condition produced the most uniform deformation profile. Prolonged annealing to 4 h resulted in grain coarsening (4168.23 µm²), decreasing UTS to 113.25 MPa and elongation to 4.59 %, while hardness increased slightly to 74.73 HV, suggesting supplementary strengthening from residual MnZn₁₃ precipitates. These results demonstrate that annealing at 400 °C for 3 h provides the optimal balance of grain refinement, strength, and ductility for the Zn-2.4Mn alloy, establishing a clear processing–microstructure–property relationship.

HYPEREUTECTIC Al–Si ALLOYS: CHALLENGES, MECHANISMS, AND ADVANCED SOLUTIONS – A COMPREHENSIVE REVIEW

Ali Mohammed Altameemi — 2026-06-08

Hypereutectic Al–Si alloys are widely used in automotive and aerospace applications due to their excellent wear resistance, low thermal expansion, and high strength-to-weight ratio. However, their performance is strongly influenced by microstructural features, particularly the morphology, size, and distribution of silicon phases, which remain critical challenges in achieving optimal mechanical and corrosion properties. This review addresses the existing research gap by providing a comprehensive analysis of microstructural evolution, processing parameters, and performance-enhancement strategies for hypereutectic Al–Si alloys. The review highlights the influence of silicon content, typically above 12.3 wt.%, on solidification behaviour, nucleation, and defect formation, including porosity and cracking. Emphasis is placed on the transformation of eutectic silicon from coarse plate-like or needle-like structures to refined fibrous or spheroidized morphologies through alloying additions and heat treatment processes. These modifications significantly improve mechanical performance, wear resistance, and corrosion behaviour. Furthermore, the role of processing techniques, including casting methods, cooling-rate control, and heat treatment (e.g., T6), is critically discussed in relation to microstructural refinement and property optimisation. The significance of this review lies in integrating findings from previous and recent studies to provide clear insights into microstructure–property relationships and practical guidelines for alloy design and processing. Future research directions are also outlined, focusing on advanced manufacturing techniques, hybrid reinforcement strategies, and computational modelling to further enhance alloy performance. This review serves as a valuable reference for researchers and engineers working on the development of high-performance Al–Si alloys.