Materials and Technology

RECENT PROGRESS IN OXIDE-DISPERSION-STRENGTHENED (ODS) ALLOYS PRODUCED BY ADDITIVE MANUFACTURING

Paul McGuiness — 2025-02-04

Oxide-dispersion-strengthened (ODS) alloys exhibit exceptional mechanical properties, making them ideal for high-temperature applications in areas such as aerospace and nuclear reactors. The traditional manufacturing of ODS alloys involves mechanical alloying, followed by processes such as hot extrusion and hot isostatic pressing. However, these methods are limited when it comes to producing complex geometries. Recent advances in additive manufacturing (AM) techniques, specifically selective laser melting (SLM) and directed-energy deposition (DED), offer exciting new possibilities for fabricating ODS alloys. Early research demonstrated the feasibility of using SLM to create complex parts with uniformly dispersed oxide particles, thereby enhancing the materials’ properties. Subsequent studies confirmed that optimising the SLM parameters could further improve the mechanical performance of ODS alloys. DED techniques have also shown promise, with innovations like in-situ oxide formation during deposition and high-speed laser cladding. These methods have achieved success by producing ODS materials with refined microstructures and enhanced mechanical properties. The latest research continues to explore the potential of AM for ODS alloys, focusing on improving the dispersion of nanoparticles and minimising the tendency of particles to agglomerate. Overall, AM has advanced the fabrication of ODS alloys by offering efficient production routes and the ability to create intricate designs with superior properties.

INFLUENCE OF MICROALLOYING AND THE THERMOMECHANICAL METHOD OF PROCESSING ON THE COMMINUTION OF THE COPPER STRUCTURE

Milijana Mitrović — 2025-02-04

Copper, as a basic element, was alloyed with iron (Fe) and phosphorus (P). This paper presents the results of the copper structure comminution in the Cu-Fe-P alloy, with the chemical composition containing 0.003 w/% and 0.014 w/% of Fe and P, respectively, and with certain mechanical and structural characteristics. A homogeneous Cu-Fe-P alloy was synthesized to generate certain mechanical and structural properties, meeting the strict requirements of industry. These requirements refer to Vickers hardness (HV10) which should be from 45 to 70, tensile strength (R_m) with a minimum of 230 N/mm², relative elongation (A) with a minimum of 40 %, and number of grains (K_z) of around 4000 grains/mm². In order to achieve the required conditions, a series of samples of the mentioned alloy were tested. Molten, chemically homogenized material was subjected to an extrusion process. Also, to achieve the above characteristics, cold processing (rolling) was used with deformation degrees of (10, 30, 50, 75, 80) %. Recrystallization annealing, for the purpose of creating a fine-grained structure, was done at 450 °C in a protective atmosphere of nitrogen and hydrogen, with annealing times of (35, 90, and 150) min. The results indicated that optimal conditions for the required mechanical and structural characteristics of the material were achieved at a deformation degree of 80 %, an annealing time of 150 minutes and a temperature of 450 °C.

OPTIMIZING WELD QUALITY IN DISSIMILAR STAINLESS STEEL JOINTS FOR INDUSTRIAL APPLICATIONS

Selvamuthukumaran Dhanasekaran — 2025-02-05

The research aims to develop quality joints using cold metal transfer (CMT) welding. We investigated stainless steel sheets such as Duplex 2205, SS 301 LN and ER 308L SS filler wire used for chemical and food processing equipment applications. The major focus was on optimizing the welding parameters for producing quality weld joints, thus ensuring the optimal ultimate tensile strength (UTS) and microhardness (HV_0.5). The Taguchi L9 orthogonal array was used in this study to find the most significant parameters among welding speed (S), current (A) and contact-to-work distance (CTWD), and their optimum settings for producing high-quality welds. The multi-objective optimization TOPSIS method was employed to optimize the ultimate tensile strength (UTS) and microhardness (HV_0.5). According to the TOPSIS performance index, the welding current was identified as the most influential factor, contributing 94.79 %, followed by welding speed and CTWD contributing 4.48 % and 0.15 %, respectively. The optimized welding parameters including a current of 95 A, welding speed (travel speed) of 4 mm/sec, and CTWD of 5 mm were identified as the best results. Confirmatory experiments were conducted to validate the optimized settings; they demonstrated good agreement with the predicted results. Finally, optical microscopy (OM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDXS) analyses of the optimal weld microstructure were presented.

EXPERIMENTAL STUDY OF THE EFFECT OF FINE AGGREGATE IN PERVIOUS CONCRETE

R. Rahul — 2025-02-05

Pervious concrete is categorized as porous concrete due to its pore structure and high permeability. The permeability coefficient generally increases with porosity. A 4.75–12.5 mm coarse aggregate is used to make pervious concrete. An experimental study on the impact of a fine aggregate in pervious concrete is conducted in our investigation. The research mix design is done in accordance with American Concrete Institute 522R-10 and Indian Standard 10262. The proportion of water to cement is kept constant. Also, fine aggregates are added to the mix in increments of 2 %, ranging from 0 to 10 %. After adding a fine aggregate, the measured permeability yields various findings. The permeability of pervious concrete diminishes as fine aggregate is added. Also, various parameters such as compressive strength, porosity, split tensile strength, flexural strength and density are computed and analysed. American Concrete Institute 522R-10 states that designs should not include fine aggregate additions greater than 10 % of pervious concrete mixes. Beyond this point, strength is reduced. The flexural strength, compressive strength and splitting tensile strength of pervious concrete mixtures are all increased at an 8 % sand content.

ASSESSMENT OF WEAR AND CORROSION RESISTANCE IN TiC AND WC COATINGS APPLIED TO AISI 1040 FORGED STEEL VIA ELECTROSPARK DEPOSITION

D. R. P. Rajarathnam — 2025-02-05

Electrospark deposition is a very efficient technique used to improve metallic material surfaces by applying ceramic coatings. This investigation employed the electrospark deposition approach to deposit titanium carbide and tungsten carbide coatings onto the surface of AISI 1040 forged steel. Subsequently, the coated surfaces were subjected to a microstructure examination, phase structure analysis, microhardness testing, friction testing, wear testing, and electrochemical corrosion testing. After that, the outcomes were compared to those of uncoated AISI 1040 forged steel. The forged steel with TiC and WC phase coatings applied with electrospark deposition was much better than the untreated AISI 1040 forged steel in terms of hardness, being more than four times harder. Both the friction coefficient and wear volume loss were reduced as a result. Furthermore, due to their decreased conductivity, the ceramic coatings that were applied to the surface showed a corrosion resistance that was 2–3 times higher than that of the uncoated forged steel. While TiC coatings may better enhance corrosion resistance, this study provides evidence that WC coatings could be a superior choice for improving the wear resistance of AISI 1040 forged steel.

OPTIMIZATION OF WELDING PARAMETERS OF ELECTRICAL RESISTANCE SPOT WELDED 6082-7075 ALUMINIUM JOINTS USING THE TAGUCHI METHOD

Şafak Işik — 2025-02-05

In this study, aluminium alloys of AA6082 and AA7075 series were welded with resistance spot welding. Effects of welding current intensity, welding time, and electrode pressure on the tensile strength and microstructure were examined, and their optimized values were determined using the Taguchi method. While performing optimization, the L₂₄ orthogonal array was used with the Taguchi method. With this array, the signal/noise (S/N) ratio became the determining factor in controlling the optimization results. Comparing the experimental procedures and analysis results, the results obtained from the real application and Taguchi analysis were found out to be similar.

RESEARCH ON PAVEMENT PERFORMANCE OF WATERBORNE EPOXY RESIN-MODIFIED EMULSIFIED ASPHALT BINDERS AND POTHOLE REPAIR MATERIALS

Fan Yang — 2025-02-05

Traditional emulsified asphalt pothole repair materials exhibit poor temperature sensitivity, low mechanical properties, and poor water stability. Two-component waterborne epoxy resin (WER) is composed of epoxy emulsion and a curing agent, and has remarkable mechanical properties, adhesion, durability, and environmental friendliness. Two-component waterborne epoxy resin (WER) was used to modify neat emulsified asphalt, enhancing its binder properties and improving the pavement performance of pothole repair materials. The influence of the WER modifier on the pavement performance of emulsified asphalt binder and its mixture was studied. The research showed that the WER emulsion and curing agents could polymerize and produce epoxy resin under emulsified asphalt as the dispersion medium. Fourier transform infrared spectra analysis indicated that the modification of the emulsified asphalt by WER was mainly physical. With an increase in the WER content, the mechanical properties and high-temperature deformation resistance of waterborne epoxy resin-modified emulsified asphalt (WEA) binder were significantly improved while ductility was decreased. The mechanical properties of the WEA mixture had an excellent linear correlation with the water-loss rate. When the WER content exceeded 15 %, the mechanical properties, water stability, high-temperature stability, and anti-stripping performance of the WEA mixture were significantly improved. When the WER content was less than 20 %, the modifier played a reinforcing role in the emulsified asphalt binder, and the low-temperature crack resistance of the WEA mixture gradually improved with the increase in the modifier content. After exceeding the critical content, the WEA mixture gradually exhibited brittleness and hardness, and its low-temperature performance decreased. In summary, it was recommended that the WER modifier content range be 15–20 % for the pothole repair material system.

INVESTIGATION ON MICROSTRUCTURAL AND GEOMETRICAL CHARACTERIZATION OF COLD METAL TRANSFER HARDFACED INCONEL 718 ON MEDIUM CARBON STEEL

P. Keerthivasan — 2025-02-05

This study presents a compelling exploration of the microstructural and mechanical enhancements achieved with Inconel 718 hardfaced layers on AISI 1045 medium carbon steel through the advanced cold metal transfer (CMT) process. By precisely adjusting process parameters such as travel speed and wire feed rate, this research examines their effects on bead geometry and dilution for both stringer- and oscillation-type depositions. Microstructural analysis unveiled defect-free hardfaced layers, achieving seamless metallurgical bonding between the substrate and hardfacing material. Notably, oscillation-type deposition with optimized parameters (6 m/min wire feed rate and 20 cm/min travel speed) achieved an impressively low dilution of 3.38 %, surpassing stringer-type deposition in quality. Furthermore, hardness testing highlighted a significant improvement in the surface durability as oscillation-type deposition reached 254 HV, while the value of the substrate was 172 HV. SEM-EDX analysis confirmed the inclusion of critical alloying elements such as nickel, niobium, and molybdenum, reinforcing the hardfaced layer’s robust composition. These findings underscore the CMT process’s capacity to fabricate high-quality, low-dilution Inconel 718 hardfaced layers, providing substantial resistance to corrosion and wear. The finely tuned parameters identified here offer valuable guidance for the industries seeking enhanced performance in demanding environments.

PRELIMINARY INVESTIGATION INTO THE FORMATION OF LiCo0.8M0.2O2-δ (M = Zr, Ca) AS TRIPLE-CONDUCTING OXIDE CATHODES FOR SOLID OXIDE FUEL CELLS

Muhammad Amirul Mamsor — 2025-02-05

A solid oxide fuel cell (SOFC) is an efficient electrochemical energy conversion device with low emissions. The cathode is one of the principal components of an SOFC, responsible for the reduction reaction. Triple conducting (H⁺/O^2–/e^–) cathodes are promising due to their enhanced performance, but existing materials like LiCoO₂ (LCO) face stability issues at high temperatures caused by a high cobalt content. Hence, the study focused on synthesizing LiCo_0.8M_0.2O_2-δ (M = dopant) using a glycine-nitrate process and introducing dopants (Zr/Ca) to the cobalt site of LCO to improve stability. Synthesized cathode powders were analyzed using a thermal gravimetric analysis (TGA), X-ray diffractometry (XRD), and field emission scanning electron microscopy/energy dispersive X-ray spectrometry (FESEM/EDX) to assess the thermal decomposition behavior, phase and structure formation, and microstructure, respectively. The XRD analysis confirmed a successful synthesis of homogeneous LiCo_0.8M_0.2O_2-δ cathode powders (M = Zr, Ca) at a calcination temperature of 800 °C. The FESEM/EDX analysis indicated homogenous elemental distribution within the powders, with final experimental molar ratios of LiCo_0.79Ca_0.21O_2-δ and LiCo_0.78Zr_0.22O_2-δ for the Ca- and Zr-doped cathodes, respectively. This successful synthesis paves the way for further research on the stability and performance of these doped cathodes in SOFC applications.

SIMULATION OF HIGH-TEMPERATURE CORROSION BEHAVIOR OF Ti6Al4V ALLOY IN MARINE ENVIRONMENTS

Rongtao Zhu — 2025-02-05

High-temperature oxidation and corrosion behavior of Ti6Al4V alloy at 650 °C for 1000 h were investigated using a salt mixture (25 w/% NaCl and 75 w/% Na₂SO₄) as the thermal corrosion medium. The mass increase due to the alloy’s oxidation and thermal corrosion were analyzed quantitatively. The surface morphology and cross-sectional structure of the alloy after oxidation and thermal corrosion were scrutinized and analyzed via X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Results show that Ti6Al4V alloy exhibits a certain antioxidant property in a high-temperature oxidation environment at 650 °C, but this antioxidant property is gradually weakened with the prolongation of the oxidization time. The synergistic effect of oxygen and hot salt further accelerates the corrosion degradation of the oxide layer of Ti6Al4V alloy in the high-temperature hot-salt environment at 650 °C.

RESEARCH ON THE WATER-HOLDING CAPACITY AND MECHANICAL PROPERTIES OF BACKFILL BASED ON A DAMAGE-SOFTENING CONSTITUTIVE MODEL: EFFECTS OF DIFFERENT PERMEABILITY FORCES

Chaoyi Yang — 2025-02-06

This study investigates the application of tailings backfill through a series of centrifugal and pore characteristic tests. To align with the material’s structural properties, a specialized test mold was developed, enabling the preparation of tailings backfill model samples with varying concentrations and proportions. Employing centrifugation and nuclear magnetic resonance (NMR), the study determined the optimal centrifugal force and the T2 critical value for the backfill material. By simulating seepage pressures induced by different centrifugal speeds, uniaxial compression mechanical tests were conducted to analyze the effects of seepage forces on the deformation characteristics and failure modes of the backfill. The results revealed that as seepage force increased, the stress-strain behavior of the samples was altered, with failure modes transitioning from tensile failure to shear failure. This shift was accompanied by an increase in the crack propagation and morphological complexity. Based on these findings, a damage-softening constitutive model incorporating penetration forces was established and validated against experimental data, demonstrating strong agreement. This model provides a robust framework for analyzing uniaxial compression mechanics of backfill materials under varying penetration forces. The outcomes of this research provide valuable insights into high-gravity centrifugal simulations and underground seepage tests, contributing significantly to the design and safety evaluation of tailings backfill systems.

HYDROTHERMAL SYNTHESIS AND CHARACTERIZATION OF ZSM-5 ZEOLITE FROM ANORTHOSITE: IMPACTS OF REACTION TIME AND TEMPERATURE

Yonas Desta Bizualem — 2025-02-06

Anorthosite was used as the alumina source while applying a hydrothermal method for the synthesis of ZSM-5. The anorthosite sample, obtained from the Soji-Bikilal region of Ethiopia, was pre-treated and activated with NaOH at a 1:2 (wt/wt) ratio. ZSM-5 type zeolites were made from the anorthosite rock utilising hydrothermal synthesis at reaction times of (24, 48, and 96) h at a reaction temperature of 100 °C, in accordance with the alkaline fusion technique. UV-vis spectra, X-ray diffraction, scanning electron microscopy and BET surface area were used to characterize anorthosite and synthesized ZSM-5 zeolite. The highest noticeable reflection peak for the ZSM-5 zeolite synthesised at the reaction temperature of 100 °C and reaction time of 96 h was at 24.7°, showing that the material was extremely crystalline. According to their microstructures, anorthosite features platy crystals and amorphous particles, while ZSM-5 zeolite exhibits spherical crystals with some amorphous gel.

COMPONENT OPTIMIZATION OF g-C3N4/TiO2 HETERO- STRUCTURE COMPOSITE AND ITS ACTIVITY ENHANCEMENT FOR PHOTOCATALYTIC DEGRADATION OF RHODAMINE B

Zikang Cao — 2025-02-06

In this study, g-C₃N₄/TiO₂ heterostructure composites were synthesized using sol–gel and hydrothermal methods. Through X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), the crystalline phase structure and chemical composition of the composite were confirmed. Scanning electron microscopy (SEM) revealed that the g-C₃N₄ sheets were uniformly dispersed on the block TiO₂ particles. Ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis/DRS) indicated that the incorporation of g-C₃N₄ resulted in a narrowing of the forbidden bandwidths of the composites. Photoluminescence (PL) spectroscopy and electrochemical impedance spectroscopy (EIS) further demonstrated that the g-C₃N₄/TiO₂ heterostructure effectively suppressed the recombination of photogenerated charge carriers. To evaluate the photocatalytic performance of g-C₃N₄/TiO₂ heterojunction composites, different g-C₃N₄ loadings were tested for degradation of rhodamine B (RhB). The 7.62 w/% g-C₃N₄/TiO₂ heterojunction composite exhibited the highest degradation efficiency for RhB dye, with a constant degradation rate that was twice as high as that of pure TiO₂. Additionally, experiments on free radical trapping of the composite revealed the crucial role of hydroxyl radicals (·OH) and photogenerated holes (h⁺) in the RhB degradation. Moreover, the formation of a Z-scheme heterojunction between g-C₃N₄ and TiO₂ was the main factor in further enhancing the degradation activity of the composite.

THERMAL DEFORMATION BEHAVIOR OF HIGH-PURITY RARE EARTH METAL DYSPROSIUM

Haishuang Lv — 2025-02-06

High-purity rare earth metal dysprosium was subjected to a single-pass thermal compression test at temperatures ranging from 300 °C to 700 °C and strain rates ranging from 0.1 s^–1 to 10 s^–1 using an MMS-200 thermal simulation testing machine. The true stress-strain curves, macro and microstructure of dysprosium were analyzed, leading to the establishment of processing maps and constitutive equation for dysprosium. Results revealed that the stress of dysprosium decreased with increasing deformation temperature and decreasing strain rate. Moreover, as the strain rate reached 5 s^–1, the stress-strain curve gradually transitioned from dynamic recovery to dynamic recrystallization, with a more pronounced softening behavior observed at higher strain rates. Based on the processing diagram and sample microstructure analysis, it was determined that the optimal deformation range for dysprosium is between 350 °C and 500 °C at a strain rate of 1–10 s^–1.

EXPLORING HAZELNUT SHELL-DERIVED CARBON AS AN ECO-FRIENDLY ADDITIVE IN BICYCLE TIRE MANUFACTURING

Esra Çetin — 2025-02-06

Recently, the tire industry has focused on eco-friendly practices, particularly on integrating waste materials into rubber formulations. Natural alternatives to carbon have offered a promising way to lower the carbon footprint by promoting recycling. This study explored the incorporation of carbon derived from hazelnut shells (HSC), an agricultural byproduct, as an additive in bicycle tire manufacturing. Bicycle tire formulations were prepared by maintaining a constant total carbon filler content of 28 parts per hundred rubber (phr). Initially, 28 phr of commercial carbon black and 0 phr of HSC were used. In subsequent formulations, the carbon black content was gradually reduced to (21, 14, 7, and finally 0) phr, while the HSC content was correspondingly increased to (7, 14, 21, and 28) phr to replace the reduced commercial carbon black. The produced tires were analyzed using density measurements, Mooney viscosity (MV), Mooney scorch (MS), rheological evaluations, mechanical testing, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), plunger tests, and rolling resistance tests. The study demonstrates that, although increasing the amount of HSC in tire compositions reduces the mechanical performance, the required performance standards for bicycle tires are still met.

CHARACTERISATION OF NON-METALLIC INCLUSIONS IN Pb-Ca-Sn ALLOYS

Maja Vončina — 2025-02-06

Non-metallic inclusions in two Pb-Ca-Sn lead alloys used in the manufacture of lead-acid batteries were investigated and categorised. Samples of recycled lead alloys were analysed using scanning electron microscopy (SEM) in combination with energy dispersive X-ray spectroscopy (EDS). This technique enabled the analysis of the chemical composition of the alloys and the identification of non-metallic inclusions. Differential scanning calorimetry (DSC) confirmed the presence of non-metallic inclusions in two different recycled alloys. Non-metallic inclusions in lead alloys are detrimental, negatively impacting both the casting process and the mechanical and electrochemical properties of the alloys. Results indicate that oxide inclusions are predominant in Pb-Ca-Sn alloys. Non-metallic inclusions with stoichiometric compositions of PbO₂, Pb₂O₃, Al₂O₃, and CaO were identified. Most of these inclusions were found near the surface of a sample, i.e., in the area most exposed to the atmosphere. The introduction of a protective atmosphere during the melting process could significantly reduce the occurrence of non-metallic inclusions.