Archives of Metallurgy and Materials

In this study cutting speeds and tool life constants for seven different cutting tools are investigated while high-speed face milling of four different much used hardened tool steels.1.2379 and 1.2080 cold-work tool steels, 1.2344 hot-work tool steel and 1.2738 plastic mold steel were machined with PVD TiN coated ceramic, PCBN, PVD TiN coated carbide, PVD TiAlN coated carbide cermet, CVD TiN-TiCN-Al2O3 coated carbide, uncoated carbide and uncoated cermet cutting tools. Wear of cutting tools measured for all species after every pass. Also, the tool life constants for each tool materials are calculated and are given for convenient tool material. Generally, PCBN tool gave the best results in high-speed face milling of all hardened tool steels. Unexpectedly uncoated carbide and uncoated cermet gave useful results while high-speed face milling of hardened 1.2344 hotwork tool steel.

To confirm the impact of Li₂O and Na₂O on the structure and property of CaO-SiO₂-B₂O₃ based fluorine-free mold fluxes, devices including rotary viscometer, X-ray diffraction, combined with Fourier transform infrared (FTIR) spectroscopy were applied in the present study. From FTIR results, it was noted that with the addition of Li₂O (0-3 wt%) and Na₂O (4-12 wt%), there would be simpler Si-O and B-O structural units formed. However, all the structure units were intensified when the content of Li₂O (4 wt%) was added in slag. By the accumulation of Li₂O and Na₂O in mold fluxes with various BaO content, the viscosity at 1300℃ decreased generally, showing that viscosity was influenced by the combination of structure and superheat, and superheat gradually played a dominant role as Li₂O reached 4 wt%. Depending on the viscosity-temperature curve, all samples showed acidic slag characteristics and the decrement activation energy of slag came as the increment of Li₂O and Na₂O at the basicity 1.15 in overall, which were beneficial for the play of slag lubrication function. The effect of Li₂O on crystallization of fluorine-free mold fluxes with 5 wt% of BaO were analyzed that all the diffraction peaks displayed in the XRD patterns corresponded to the standard peaks of Ca₂SiO₄ and Ca₁₁Si₄B₂O₂₂. Li₂O has an imperative role in all samples that enhanced the crystallization performance of the mold fluxes in the low-temperature zone.

The development and characterization of nanochitosan-YSZ (Yttria-Stabilized Zirconia) duplex coatings on 316L stainless steel using a dual method for dental applications are the focus of this study. Dental implants have long been integral to restoring oral health, but the high cost of noble material-based implants limits their accessibility to many individuals. As a solution, this research explores the use of innovative materials and techniques to create cost-effective yet biocompatible dental implants. The study involves a dual coating method that combines electrophoretic deposition and dip coating to create a robust and adherent duplex coating. Nanochitosan, a biopolymer, and YSZ, known for its excellent cell adhesion properties, form the basis of the coating material. The characterization of the duplex coatings includes various analytical techniques to assess their physical and chemical properties. This research aims to enhance the long-term stability and functionality of dental implants, making them more affordable and accessible to a wider range of patients, thereby contributing to improved dental health and quality of life.

Wire arc additive manufacturing (WAAM) is amongst the emerging technologies of the layer-by-layer deposition process to manufacture the metallic parts. Multi-layer bead deposition using the WAAM process leads to the fabrication of complex products with practical utility. The bead profile of each layer controls the geometry of the final product. However, the melting efficiency and the bead geometry depend on the various process parameters. The primary process parameters affecting the melting efficiency and the bead geometry are the wire feed rate, travel speed, diameter of the wire, and power. Owing to the various complexities during metal deposition, predicting the dimensions at each deposition attribute is not always feasible. Hence, the current work is focused on the utilization of different machine learning (ML) algorithms to understand the relationship between the process parameters, melting efficiency, and bead geometry. The different ML models used for the current work are linear regression (LR), decision tree regressor (DTR), random forest (RF), support vector regression (SVR) and, extra tree regressor (ETR). The ETR is found to predict the melting efficiency with the highest prediction rate of 97.4%, whereas, the SVR and LR predict the bead width and height with the highest accuracy rate of 97.4% and 98.7%, respectively.

Resistance spot welding (RSW) involved two or more sheets of metal that are welded together with or without filler mate­rials. This paper discussed the optimization of RSW process parameters that were varied on galvanized steel below 6 kA by using Taguchi method. Galvanized steel can be more difficult to spot weld than any other uncoated metal due to the tendency of zinc coating alloying with electrodes. The three process parameters are welding current, welding time and holding time. The type of OA used in this study was L9. Subsequently, tensile and Vickers microhardness tests were conducted on the sample. Results from these tests were used to calculate the S/N ratio, ANOVA and confirmation test. The optimal parameters value and percentage of contributing factors to the welding can be identified. It will help to produce high-quality weld joints.

Magnesium matrix composites are being used in more and more different ways, so they need to have good surface properties like resistance to wear and corrosion. In this work, we used friction stir processing to make ZE43 magnesium surface composites with different amounts of Si3N4 particles (by volumes 6.0%, 12.0%, and 18.0%, respectively). X-ray diffraction and scanning electron microscope analysis showed Si3N4 particles in the developed magnesium surface composite are all uniformly distributed. After FSP, the composites were tested for hardness. Using Potentio dynamic polarization, the corrosion behavior of both the base matrix material and composites made were studied. The composite containing 18% Si3N4 has the highest corrosion resistance .The composite’s sliding wear behavior and coefficient of friction analyzed by a pin-on-disc tribometer by changing the amount of Si3N4 in the material, load and sliding distance. To attain the highest possible wear resistance and coefficient of friction, parameters of the process were optimized with the help of taguchi grey relational analysis. The results show that load, followed by volumetric percentage, and sliding distance have a substantial effect on wear rate and friction coefficient.

Borate mineral chambersite (Mn₃B₇O₁₃Cl) is a kind of manganese-chloride-borate mineral with great application prospect. China is the only country has the borate mineral chambersite deposits in the world at present. It is of great theoretical and practical significance to develop and utilize raw Mn₃B₇O₁₃Cl and synthetic nano- Mn₃B₇O₁₃Cl, and study its microstructure and properties. This review provides an overview of the microstructure, photoluminescence, gamma ray irradiation and neutron irradiation properties, electromagnetic properties, anti-tumor, anti-bacterial properties, as well as friction and wear properties of Mn₃B₇O₁₃Cl, which provides a theoretical basis for further development and application of Mn₃B₇O₁₃Cl.

Fly ash-based geopolymers’ quality varies based on their constituent materials’ quantity and reactivity. Determination of the ratio of fly ash as a base material reacted with the ratio and quantity of the alkaline activator as a reagent is a challenge in producing a stable geopolymer reaction. This study aimed to provide insight into the stability of the mixture of fly ash-based geopolymers. Variations in the ratio and amount of alkaline activator to fly ash in a wide range of quantities could provide an overview of the stability of the geopolymer reaction. The fundamental indicators of the stability characteristics of geopolymers are their physical stability and changes in strength. Evaluation of the stability of the geopolymer mortar was observed from the development of compressive strength, visual inspection of efflorescence during partial immersion, and the strength changes after a heating treatment of 150°C for 4 hours. The results showed that the more alkaline activator content in the mortar, the stability of the resulting geopolymer is reduced, as seen from the appearance of efflorescence on the specimen surface, expansion cracks, and a decrease in compressive strength. The ratio of alkaline activator also affected the compressive strength resulting in a range of optimum ratios. Meanwhile, depending on the calcium content in the fly ash, a secondary pozzolanic reaction could also occur in the geopolymer concrete at a later age.

The characterization of low-grade ilmenite ore from Banten (Indonesia) is investigated, as well as the effects of particle size, NaOH:Ti ratio, and fusion time on Ti and Fe content in TiO₂ products. Mineral separation of low-grade ilmenite ore was performed using wet gravity, followed by sieving. Each sample size’s magnetization (using 10,000 Gauss magnets) is followed by weighing the magnetization results. The sifted and magnetized samples were then analyzed with XRF for composition analysis and XRD for compound determination. FE-SEM was applied to analyze morphology. A microscope was used for metalografi analysis. The fusion temperature of the optimization process was determined using STA. Fusion times were 10, 30, 60, 90, and 150 minutes at 850°C, with a NaOH:Ti ratio (w/w) of 1:2, 2:1, and 4:1, and particle sizes of 0.177-0.149 mm, 0.149-0.105 mm, and 0.105-0.074 mm. The minerals ilmenite (FeTiO₃), magnetite (Fe₃O₄), and coesite (SiO₂) dominate the characterization of Banten low-grade ilmenite ore. Sixty minutes of fusion at 850°C with a 2:1 NaOH:Ti ratio (w/w) and 0.177-0.149 mm with 94.44% TiO₂ in a product was optimal.

Magnesium containing 3 weight percentages of aluminium particles and 5.6 weight percentages of titanium particles (reinforcement) was prepared using the disintegrated melt deposition technique to investigate their synergistic effect on the tribological behaviour of Mg-3Al/5.6Ti composite. Metallographic features of the composite samples were analysed using x-ray diffraction analysis and scanning electron microscopy to disseminate the particle distribution and phase formation. The wear behaviour of the samples was studied using dry sliding wear testing by systematically varying load and sliding velocity over a sliding distance of 2000 m. The post-failure analysis was performed on the worn surface of pins, and the collected debris using scanning electron microscopy and the mechanisms involved in the wear behaviour of composite samples were identified.

This study investigates the impact of printing parameters on fused filament fabrication parts using Polylactic acid and polylactic acid carbon fibre filament. It aims to determine the ideal conditions for 3dprinter to increase the strength of these materials. The study uses to find the effects of infill density, orientation, and layer height on the mechanical characteristics of the materials. Polylactic acid Carbon Fiber is found to be more rigid and have higher tensile strength than Polylactic acid. The most significant parameter influencing results is polylactic acid, despite its more apparent effect. The study suggests that the manufacturing parameters to print the part and can result in higher polylactic acid carbon fibre strength than polylactic acid filament, providing valuable insights for model design and manufacturing. Infill density impact less compare to other two parameter of layer height and orientation. Compare to polylactic acid composite polylactic acid carbon fibre influence the parameters to increase of strength.

M 50 NiL steel is a variety of tool steel having high toughness. This steel is potential materials for several bearings of aero-engine. This steel is used in carburized condition. However, nitriding has several advantages over carburizing. The main goal of this work is to compare and contrast the microstructural features, mechanical properties and tribolgical performances of this steel nitrided by gas, liquid and plasma nitriding processes. In view of the above, M 50 NiL steel was nitrided by the processes mentioned above. Microstructural characteristics, mechanical properties, sliding wear response in unidirectional and reciprocation mode were evaluated. The results reveal formation of compound layer in gas and plasma nitrided samples. Surface hardness was comparable for all three nitrided layers. Liquid nitrided specimen indicates best wear resistance in unidirectional and reciprocating sliding conditions. The friction coefficient is lower and wear rate is higher under reciprocating sliding than under unidirectional sliding. While delamination cracks are the main features of unidirectional sliding, cracks perpendicular to the surface were noted under reciprocating sliding.

Robotic arm technology coupled with Cold metal transfer (CMT) has revolutionized Wire arc additive manufacturing (WAAM), gaining widespread recognition in the aerospace, marine, and automotive sectors. In WAAM, managing residual stress poses challenges due to temperature gradients, phase transformations, and uneven cooling, leading to distortion and potential crack failures. This study is centered on the CMT-assisted fabrication of SS 316L WAAM utilizing a 1.2 mm diameter. It involves a comparative analysis of residual stress, microhardness, ultimate tensile strength, and percentage elongation between SS 316L WAAM, and the results were compared with those of wrought SS 316L. The WAAM sample quantified an average residual stress of 90.73 MPa (compressive), marking an 18% increase compared to the wrought stainless steel’s residual stress of 76.68 MPa (compressive). The microhardness profile of the WAAM sample revealed an average value of 269.51 HV0.5, signifying a substantial 4.48% increase over the wrought SS 316L microhardness of 257.94 HV0.5. The WAAM sample’s ultimate tensile strength was 577 MPa, 16.56% greater than the wrought SS 316L, having an ultimate tensile strength of 495 MPa, while their respective percentage elongation was 86% and 87%. WAAM demonstrated superior performance in terms of ultimate tensile strength, residual stress, and microhardness.

This study intended to investigate the impact of two distinct shaping methods, Injection molding and pellet additive manufacturing, on tensile and thermal properties of PLA based materials. It included comparisons of neat PLA and PLA reinforced with carbon nanoparticles derived from groundnut shells (GNSC) via pyrolysis at 800°C. These nanoparticles were characterized using FTIR, XRD, FESEM, and EDX analyses to assess their carbon content, morphology, and structure. The synthesized carbon was used as a reinforcement filler in the PLA matrix and biobased polymer nanocomposites were prepared by pellet 3D printing and injection molding. The mechanical and thermal characteristics of PLA/GNSC composite specimens with 0.25, 0.5, and 0.75 wt% of GNSC nanoparticles were compared. Reinforcing PLA with GNSC nanoparticles improved tensile properties in both shaping techniques. The PLA/GNSC_0.5 exhibited the greatest tensile strength, measuring 58.61 MPa for injection molded samples and 53.05 MPa for 3D printed samples, representing a 50% enhancement compared with neat PLA. The tensile modulus was also highest for PLA/GNSC_0.5, measuring 1.24 GPa for injection molded samples and 1.21 GPa for 3D printed samples, representing an improvement of 14% compared with neat PLA. The tensile characteristics showed a modest increase in tensile strength (9-13%) and a slight improvement in tensile modulus (2-3%) for injection molded samples compared to 3D printed samples. The thermal properties showed no substantial variation between the two shaping methods. These findings highlight the effectiveness of GNSC nanoparticles in enhancing the mechanical and thermal performance of PLA composites, regardless of the shaping technique.

Industry 4.0, also known as digital manufacturing, is a new revolution in the manufacturing industry that employs tools such as reverse engineering, additive manufacturing, and design optimization techniques such as generative design. This most recent technological advancement can be used to enhance existing designs and products for performance and efficiency with the power of computation. Reverse engineering is a technique or approach in which one tries to understand, using deductive reasoning and little to no understanding of how something works, such as how a previously created device, process, system, or piece of software performs a function. It can be used to collect visual data to recreate models of desired objects using 3D scanning methods. This study used these various advances to optimise a 3D-printed brake pedal. It entailed reverse engineering the brake pedal using 3D scanning, followed by optimising the brake pedal design for mass and shape using generative design. The 3D printing process was optimised through a parametric study of the process parameters which include Type of Material, Layer Thickness, Infill Density, Infill Pattern, and Raster Angle. The result of experiment is revealed that material type (33.63%), Infill density (20.48%) and Layer Thickness (20.41%) significantly influencing the tensile strength of the 3D printed specimen. It also showed that Infill density (31.06%), material type (21.54%) and Layer Thickness (20.41%) are the most influencing process parameters of Impact strength. The findings were unified and used to create a Lightweight Polymer Brake Pedal optimised for High-Performance Applications in Electric Vehicles.

CMT-WAAM, an advanced manufacturing technology, garners significant attention due to its ability to fabricate intricate components efficiently. In this investigation, a 40-layered structure was manufactured from SS 316L using the CMT-WAAM process, with the utilization of optimized process parameters. This research involved the analysis of microstructure and mechanical properties, including microhardness, tensile testing, and fractography, for both WAAM and wrought SS 316L. The UTS of WAAM reached 592.31 MPa and YS of 276.46 MPa, outperforming the UTS of wrought 316L, which was 557.62 MPa, and YS of 284.35 MPa. The PE of WAAM was 59.85%, while for wrought 316L, it was 53.20%, indicating that wrought 316L demonstrated a higher ductility than the WAAM part. The microhardness profile of WAAM showed an average value of 238.14 HV, indicating a 28% increase compared to the MH of wrought 316L, which was measured at 192.37 HV. The microstructure of CMT-WAAM displays δ-ferrite and γ-austenite, along with skeletal and lathy ferrites, similar in wrought 316L. The fractography analysis of tensile specimens exhibited numerous dimples, indicating favorable ductility in the fabricated structure. Therefore, the findings indicate that the CMT-WAAM process meets industrial requirements.

Machining with clean and ecofriendly is current objective in manufacturing industries. Researchers are focusing on textured cutting tool inserts for a rake face coupled with solid lubrication to enhance a clean approach in machining. But there are a few issues with solid lubricants, such as supply methodology and durability at high temperatures. To avoid this issue, two different approaches are attempted. The first approach is textured cutting inserts are coated with titanium nitride (TiN) ceramic elements and the second one is cryogenic treatment. Micro hole pattern texturing on rake face is introduced. Textures are introduced using Electrical Discharge Drilling (EDD) to improve the dimensional accuracy of micro hole. Al based Metal Matrix Composites (MMC) with Multiwalled Carbon Nano Tube (MWCNT) is used as workpiece material. The machining performances are studied with the input process parameters of machining speed, feed rate and depth of cut. surface roughness and power consumption are considered as output parameters. The result is that machining performance is improved with cryogenically treated cutting inserts than ceramic coated and solid lubricant filled textured tool inserts as 7%-10% of surface roughness reduction and 9% to 20% power consumption reduction using textured inserts with cryogenically treated. The limitations of solid lubrication are eliminated by cryogenically treated cutting inserts and TiN ceramic coated tool. The cryogenically treated tool inserts exhibit enhanced hardness and strength. This research work promotes dry machining effectively with the help of cryogenically treated textured tool.

The most used raw materials to produce geopolymers are metakaolin, fly ash, mine tailings, and granulated blast furnace slag. The geochemical composition of the starting materials is decisive for the structure and physical properties of the newly synthesized geopolymer. The present research is aimed at validating methods to determine pH, electrical conductivity of initial raw materials for the preparation of geopolymers. Methods trueness and precision were estimated by bias, z-score and repeatability determination. The results from certified reference material clay soil for pH and EC CRM498-100G, Lot LRAC5544 tests showed that the bias was 0.18% for pH and –1.7% for EC. The repeatability was 0.18% and 2.38% for pH and EC, respectively. The z-score was below 2 and the analytical behavior of both studied methods was evaluated as satisfactory. The validated procedures were applied to mine tailings and coal combustion by-products from four sources from Bulgaria, Romania, and Portugal. The aqueous slurry of industrial wastes was with pH 6-12, all studied fly ashes contained high concentration of components ionized in water solution. The results showed that the studied raw materials could be used as precursors for geopolymer.

In the realm of high-power LED applications, several critical concerns emerge, significantly impacting LED operational efficiency and reliability. Among these concerns, wire deformation during the LED encapsulation process poses a substantial threat to LED longevity. This research endeavors to investigate the influence of gold wire quantity on the LED encapsulation procedure. Leveraging ANSYS Fluent, our study employs the Volume of Fluid (VOF) technique along with a user-defined function (UDF) to model the deposition of epoxy materials onto the LED. Moreover, ANSYS Fluent is harnessed for a comprehensive analysis of fluid-structure interaction (FSI) phenomena that occur between the gold wire bonding and the epoxy materials. The FSI modeling allows us to indirectly quantify the stress exerted on the gold wire bonding during the encapsulation process. Our simulations encompass a range of gold wire quantities, spanning from 1 to 5, while a validation experiment is conducted to affirm the structural integrity of epoxy materials as per the simulation setup. Our findings reveal a direct correlation between increased epoxy material density and heightened wire deformation, stress levels, and strain distribution on the wire bonding. For EMC, which has the highest density, the maximum gold wire deformation, Von Mises stress, and strain distribution on the gold wire are 2.6616×10–8 mm, 0.00064 MPa, and 8.2019×10–9, respectively. Additionally, the simulations underscore that augmenting the number of gold wires exacerbates stress and strain distribution, assuming consistent epoxy material usage. The present study will contribute to the understanding of the mechanical aspects linked with LED encapsulation and present potential opportunities for improving manufacturing procedures and guiding future experimental attempts in this research domain.

Magnesium alloys has potential applications in aerospace and automotive industries as they are having good formability. Material properties like yield strength, ductility, have direct influence on material’s formability and product quality. At high temperature applications like aeroengine and steam engine, finding these properties are very crucial. For this purpose, uni-axial tension tests are performed at high temperatures on AZ31B magnesium alloy sheet to evaluate material formability properties. Finite element-based simulations have also been carried in LS Dyna program code. The output of the simulation is to find effective stresses and effective plastic strains. For this purpose, Tresca and Von Mises yielding conditions are utilized. These stresses are crucial in predicting and evaluating the forming limits of the material before necking. The results obtained from simulation code are consistent with experimental observations. An attempt has been made to predict formability by machine learning models. Random Forest shows the better model in predicting the formability. It has been concluded that the machine learning and Dyna code predictions has greatly minimises the physical experimentation.

Ceramics have gained extensive utilisation across diverse industrial domains owing to their exceptional mechanical, thermal, and chemical characteristics. Nevertheless, the conventional manufacturing process of ceramics frequently entails substantial energy expenditure and notable carbon emissions. Geopolymers, as a contrasting option, present an eco-friendly prospect by harnessing industrial by-products and employing alkali activation mechanisms to engender a robust binding agent. Geopolymer-based ceramics, stemming from these precursors, have exhibited great potential concerning sustainability and mechanical performance. This article presents a comprehensive review of the thermal effects during sintering mechanism of geopolymer-based ceramics. Besides, the study offers valuable insights into the intricacies of the sintering process and the ensuing microstructural evolution of geopolymer-based nepheline ceramics, thereby advancing the comprehension of geopolymer-based ceramics. The findings also provide guidance for the rational design and fabrication of sustainable ceramics materials, fostering enhancements in their mechanical properties.

The demand for polymer-based nanocomposite-reinforced nanoporous materials is becoming essential in sustainable development studies. Integrating nanoporous materials such as Metal-Organic Frameworks (MOFs) in polymer matrices is essential for developing sustainable advanced materials. Combining MOFs and polymer matrices can produce a hybrid material with improved mechanical strength and stability relative to its constituents. This study aims to elucidate the effect of synthesised UiO-66 nanoparticles in a polyurethane (PU) matrix on the subsequent hybrid materials’ microstructural and mechanical properties. UiO-66 nanoparticles were synthesised at 120°C, 130°C, and 140°C. The nanoparticles and subsequent nanocomposite were characterised using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), and Field Emission-Secondary Electron Microscopy (FE-SEM). The experimental findings indicate that the UiO-66 nanoparticles synthesised at 130°C exhibited a highly desirable crystal structure and effective adsorption properties, and the nanoparticles synthesised at this temperature were then used to reinforce PU, forming a polymer-MOF nanocomposite. The mechanical properties of the resulting nanocomposite were determined using tensile and nanoindentation tests. The UiO-66 nanoparticles were incorporated into PU matrices at various weight percentages (10 wt.%, 20 wt.%, 30 wt.%, and 40 wt.%) via the solution casting technique. The results indicated that 30 wt.% UiO-66 in the polymer nanocomposite exhibits the best mechanical properties, and loading the polymer nanocomposite beyond 30 wt.% is more likely to result in nanoparticle agglomeration and brittle behaviours

This study aims to investigate the role of bicarbonate as a co-oxidant towards facile activation of hydrogen peroxide into reactive radicals during catalysis. A different set of bicarbonate to hydrogen peroxide dosage ratios (R = 0, 0.5, 1, 5, 10, 15, 20, 25, and ∞) were varied in the presence of CaCo_0.5Fe_0.5O₃ perovskite during catalysis to enhance the oxidative degradation of carbamazepine (CBZ) micropollutants. It was found that only 10-13% of CBZ was degraded in the presence of a single oxidant (R = 0 and R = ∞). Interestingly, 98% degradation of CBZ was achieved within 45 min of reaction at an R-value of 20. This improvement in CBZ degradation was contributed to the facile generation of reactive radicals (^•OH and ^•CO₃^–) due to the efficient redox cycle during catalysis. The degradation of CBZ in the bicarbonate-activated hydrogen peroxide-CaCo_0.5Fe_0.5O₃ system at R = 20 agrees well with the Behnajady-Modirshahla-Ghanbery reaction kinetics model. These results provide new insights into the modulation of bicarbonate to hydrogen peroxide dosage ratio (R) for efficient oxidative degradation of recalcitrant micropollutants facilitated by CaCo_0.5Fe_0.5O₃ perovskite catalysts in the bicarbonate-activated hydrogen peroxide system.

Understanding the kinetics behavior of recalcitrant organic degradation in presence of catalyst is important in determining the reaction rates of catalysis. Therefore, this study investigates the kinetic behavior of oxidative degradation for different types of recalcitrant organic pollutants, namely as acid orange II (AOII) macropollutant and caffeine (CAF) micropollutant using B-site substituted CaMFeO₃ (M = Cu, Mo, Co) perovskite catalysts. The kinetic study was analyzed based on four kinetic models which are pseudo-zero-order, first-order, second-order and BMG. Interestingly, CaCuFeO₃ exhibited a unique kinetic behavior in which the reaction followed a different kinetic model: pseudo-second-order for AOII and pseudo-first-order for CAF. The reaction rate of CAF degradation in the presence of CaCuFeO₃ was increased by nine orders of magnitude (k = 1.8×10^-3 min^-1) within 4 hr of reaction compared to pristine CaFeO₃ (k = 0.2×10^-3 min^-1). On the contrary, CaFeO₃, CaMoFeO₃ and CaCoFeO₃ were fitted to BMG kinetic model for the CAF degradation. These results indicate that the partial substitution of B-site cation in the perovskite structure alters the catalytic reactivity of the resultant substituted perovskite catalysts and subsequently influences the overall kinetics behavior of the oxidative degradation in both recalcitrant macro and micropollutants.

Material selection significantly impacts crutch performance and durability, posing challenges due to various criteria and complex decision-making in engineering design. This study introduces an innovative methodology for evaluating material options in developing cost-effective multifunctional crutches. Integrating the CRITIC method for factor weighting, MARCOS for alternative measurement and ranking, and TOPSIS for preference ranking, the framework assesses seven potential materials across ten criteria. Key findings highlight cost, adjustability, and density as critical factors, with aluminium identified as the optimal frame material followed by fiberglass, striking a balance between attributes. Sensitivity analysis confirms the robustness of this approach, providing valuable insights for material selection in engineering systems and assistive technology design, enhancing crutch performance and user satisfaction. This novel approach combines established decision-making techniques, enhancing the efficiency of material selection processes for crutch design.

During the “BOF-LF-CC” process of producing low carbon Al-killed (LCAK) steel, Al in the molten steel will react with MgO in the ladle refractory or the refining slag to generate MgO-Al₂O₃ inclusions, which have a negative influence on the molten steel’s castability. To enhance the castability of molten steel, calcium treatment is typically required following LF refining to promote the transformation of inclusions MgO-Al₂O₃ to CaO-MgO-Al₂O₃ or CaO-Al₂O₃. However, calcium treatment has many drawbacks, such as low calcium yield, increased smelting cost, environmental pollution, etc. Thus, how to improve the castability of LCAK steel without calcium treatment is worth studying. In this research, laboratory studies were first carried out to clarify the source of MgO-Al₂O₃ inclusions in the molten steel. Thereafter, industrial trials were conducted with the refractory material of the ladle replaced by a MgO-free and Al₂O₃-riched refractory. The results show that when a MgO-based crucible is used at 1600℃, the inclusions in molten steel after 25 min are mainly MgO-Al₂O₃, even without refining slag. However, even with the refining slag (the basicity is less than 4.5) containing about 5% MgO, when an Al₂O₃-based crucible is employed, the inclusions in the molten steel are mainly CaO-Al₂O₃. Consequently, MgO in ladle refractories is the main source for the formation of inclusions ­MgO-Al₂O₃. The results of industrial trials using the “3 + 1” smelting pattern, in which the molten steel is cast directly without calcium treatment in the first three heats, treated with calcium in the next heat, and the process is repeated, show a significant improvement in the castability of molten steel.

To study the promotion mechanism of the quenching, intercritical quenching, and tempering process on the cryogenic toughness of 9Ni steel, the evolution characteristics of reversed austenite in the process were investigated. The mechanism of the phase transformation of reversed austenite under the partitioning of C, Ni and Mn elements was described. The experimental results showed that the composition of Ni and Mn elements is active in the intercritical quenching process. In particular, when the content of Ni in the austenite phase increased from 9.19% to 13.46%, the volume fraction of reversed austenite increased from 3.6% to 5.6%. The interstitial C atoms formed the Snoek-Kê-Köster peak, whose activation energy increased from 1.13 eV to 1.24 eV. The element partitioning promoted the formation of reversed austenite. However, intercritical quenching can lead to an even distribution of martensitic lath bundles, with smaller length and spacing. The presence of more nucleation sites can facilitate the formation of reversed austenite. After tempering treatment, a thin film of austenite can easily form along the martensite lath, resulting in improved plasticity and toughness of 9Ni steel.

This study aims to establish the optimal percentage of water treatment sludge (WTS) for incorporation into fired clay bricks, assessing both physical and mechanical properties as well as heavy metal leachability. Fired bricks were produced with varying proportions of WTS (0%, 5%, 10%, 20%, and 30%). Compressive strength, density, shrinkage, and water absorption were examined to evaluate physical and mechanical properties. Toxicity Characteristic Leaching Procedure was employed to investigate heavy metal concentrations, focusing on inorganic constituents. Results indicated that the optimal ratio for WTS in fired clay bricks is 5%, aligning with industry standards (BS 3921:1985). The 5% sludge incorporation yielded bricks with impressive attributes: a peak compressive strength of 25.40 MPa, density within standard limits, water absorption below 20%, and firing shrinkage under 8%. Notably, aluminum content, predominant in the sludge, decreased significantly from 74.17 ppm to 4.97 ppm. These findings suggest that WTS, when integrated into fired bricks, emerges as a viable, cost-effective, and environmentally friendly alternative. The study underscores the potential of utilizing up to 5% WTS in fired clay bricks, presenting a promising avenue for sustainable construction practices.

In order to improve the mechanical properties of the surface for TA15 titanium alloy, the microstructures evolution of alloys under different laser power were studied by analyzing the transformation of microstructures and the distribution of composition and hardness. The results show that the laser quenching can induce the martensite transformation of TA15 alloy, resulting in the formation of α-Ti and α’-Ti hardening phases on the surface. The morphologies of TA15 are composed of quenched layer, transition region and matrix after laser quenching. The formation of martensite α’-Ti results in the hardening layer and a hardness higher than 430 HV_0.3 on the surface of TA15 alloy. The thickness and width of the hardening layer increase with the increase of laser quenching power. When the power is 800 W, there will be the maximum thickness and width of 777 μm and 2117 μm, respectively.

The microstructure of alloy phases and hot crack propagation under TIG (tungsten inert gas) welding of Co-based superalloys are investigated. The μ-phase, β-phase and carbides are grown in the superalloy, and the μ-phase is mainly precipitated. The microhardness of the μ phase is higher than the β phase and the matrix. During TIG welding, the arc crater cracks in the molten pool are all intergranular. The equiaxed crystals are existed in the fusion zone, and the dendrites are appeared in the heat affected zone. The microcracks in the heat-affected zone and closed to the base metal are preferentially initiated in the region of the μ phase, and continuously extend to the matrix along the growth direction of the μ phase.

In the current work, the surface of WE43 Mg alloy has been modified by friction stir processing (FSP) in order to assess grain refinement on mechanical and tribological properties. After FSP, along with the decreased grain size, the reduced fraction of intermetallics (Mg₂₄Y₅, Mg₄₁Nd₅) was observed as also confirmed by X-ray diffraction (XRD) analysis. Furthermore, the altered intensity of the significant XRD peaks after FSP indicates the development of texture. Increased micro hardness (from 86.3 ± 7.9 HV_0.1 to 127.2 ± 3.4 to) and tensile strength (from 207 to 267.2 MPa) at the cost of marginally losing the ductility as reflected in decreased % of elongation from 32.02 to 29.04 were observed in FSPed alloy. The scratch test was conducted by applying three different loads (30 N, 40 N and 50 N) to assess the tribological properties of the FSPed surface. The scratch hardness obtained from the width of the scratch indicated a significant increase in the scratch hardness in the FSPed alloy compared with the base alloy. The results suggest the promising role of modifying surface microstructure by FSP to improve the mechanical performance and tribological characteristics of WE43 alloy.

Segregation of elements during solidification of massive steel castings and ingots is caused by their different solubility in the melt and in the newly formed solid phase. The macrosegregation of elements significantly affects the structure in terms of microstructure and macrostructure of the casting as well as on its mechanical and operational properties. This paper deals with the evaluation of macrosegregation of selected elements on a real cross-section of a heavy experimental carbon steel casting. Macrosegregation of elements was determined by spectral analysis at selected locations and compared with the ProCAST software and its results of casting solidification simulation. The macrosegregation was analysed along the height and width of a cross-section of the casting, which measured approximately 1800×600×100 mm. Over 300 points were analysed in this area of the casting. The results present mainly carbon segregation. The carbon segregation is compared to the solidification conditions expressed by the cooling rate and the time between the liquidus and solidus temperatures (mushy zone). The aim of this paper was also to verify the measured results with those calculated using commercial software. In conclusion, the measured macrosegregation of the carbon in the casting is different from the simulated macrosegregation, this fact is not negligible. The difference in measured carbon content is influenced by solidification kinetics and will significantly affect the material properties.

In this paper results of the thermodynamic and kinetic analysis of cobaltite oxidation process were presented. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) and energy dispersive X-ray fluorescence (ED-XRF) were used to determine the chemical composition of the examined cobaltite. The results of the chemical analysis showed that the tested sample of cobaltite mainly consists of cobalt, sulfur, calcium, arsenic, and iron, with a trace amount of some other elements. Also, some analyses were obtained by X-ray diffractometry (XRD) and scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS). Mineralogical analysis by X-ray diffractometry shows the existence of four phases: the minerals cobaltite, calcite, pyrite, and jaipurite. Based on the calculated phase stability diagram of the Co-S-O and As-S-O systems, a thermodynamic analysis of the cobaltite oxidation process was performed. The results of thermogravimetric analysis and differential thermal analysis (TG/DTG) were used to determine the mechanism of the oxidation process. Using the Sharpe method of reduced reaction half-time, a kinetic analysis was performed under isothermal conditions in the temperature range from 300°C to 900°C. The calculated value of the activation energy of the oxidation process is 8.3 kJ/mol^–1.

Based on application of Cu-based alloys and special application of Ge-based alloys it is from huge interest to study properties of the Cu-Ge-X alloys. In this paper selected system is Cu-Ge-In. This system was previously studied by our group. In this paper results are focused on electrical and mechanical properties. Experimental tests were performed on 12 ternary alloys. Six different experimental techniques were used to test the ternary alloys. The microstructure was tested using light optical microscopy (LOM) and scanning electron microscopy (SEM). The composition of the phases and the composition of the alloys were examined by energy dispersive spectroscopy (EDS). X-ray diffractometric analysis (XRD) was used to determine the phases. Properties such as hardness and electrical conductivity tests were performed. Those properties were used for calculation and modeling those properties along all composition ranges. Isothermal section at 25°C were predicted. Calculated isothermal section and were compared with results of the EDS and XRD test. Good agreement of calculated and experimental result has been reached. Best results of electrical conductivity and hardness give alloys with composition Cu_80.93Ge_9.86In_9.21.

The utilization of raw materials such as steel scrap in the steelmaking process might introduce the impurity element Sn, which significantly deteriorates the steel’s performance. Therefore, it is necessary to fully understand the mechanism of removing the residual element Sn from the molten steel. This study performed a thermodynamic calculation and investigation of residual element Sn removal in molten steel using the CaO-SiO₂-Al₂O₃ slag. The results show that when the dissolved O content in the molten steel is greater than 0.0005% and the Sn content is less than 0.254%, it is difficult to remove Sn from the molten steel ­using the CaO-SiO₂-Al₂O₃ slag alone, without incorporating other Sn removal methods. Molten slag can only help remove Sn from molten steel by adsorbing the Sn removal products. When the contents of CaO, SiO₂, and Al₂O₃ are 20~40 wt.%, increasing the SiO₂ content of the CaO-SiO₂-Al₂O₃ slag enhances the slag’s ability to absorb Sn removal products. However, as the content of Al₂O₃ or CaO in the slag increases, the slag’s Sn capacity decreases dramatically. When the CaO/Al₂O₃ ratio in the slag is 1 and the SiO₂ content is 40%, the Sn capacity reaches a maximum of 2.13×10^–7. When the CaO/SiO₂ ratio in the slag is 1 and the Al₂O₃ content is 20%, the Sn capacity reaches a maximum of 1.43×10^–7. Meanwhile, when the SiO₂/Al₂O₃ ratio in the slag is 1 and the CaO content is 20%, the Sn capacity reaches its maximum of 4.15×10^–7.

Since WWII, progress has been made in understanding how materials fail and how to prevent such failures. In this work, the newly standardized Single Edge Notch Tension (SENT) specimen is used to assess the ductile tearing resistance of 14MoV-3 steel. Crack Tip Opening Displacement (CTOD90) is measured using Unloading Compliance (UC) and Direct Current Potential Drop methods (DCPD) to measure crack growth. The tearing resistance curves were determined for the new as-received samples and after degradation by creeping. The maximum loads, the CTOD at crack initiation, and resistance curves were compared for each ageing stage. As-received specimens resulted in the highest CTOD90 compared to the creep-degraded specimens. DCPD provided a better crack prediction compared to UC.

This paper analyses the impact of thermomechanical processing history on the microstructure and thermomechanical behavior of Ti-3Al-8V-6Cr-4Zr-4Mo titanium alloy. The alloy was deformed in compression at various temperatures and strain rates, and the flow stress curves were elaborated basing on the testing data. The analysis of the material behavior at different temperature and strain rate ranges was performed taking into account various criteria of stability and instability of the material flow ­(Semiatin-Lahoti criterion and Murty’s criterion) under various thermomechanical conditions. It was shown, that the inhomogeneity of the alloy’s microstructure in the initial state, mainly due to its crystallization conditions, is also a significant factor that affects the inhomogeneity of deformation. The study indicates that the analyzed alloy needs to undergo heat treatment to homogenize its structure before it can be subjected to processing. The processing maps developed using both the Semiatin-Lahoti and Murty criteria were found to be effective in predicting flow instability and optimising hot forming parameters. The maps highlighted regions susceptible to adiabatic shear bands and strain localisation, while also identifying optimal conditions for dynamic recrystallisation and material softening. The results of this study may have direct applications in the design of thermomechanical processing of the studied titanium alloy under industrial conditions.

In this work, the microstructure and recrystallization behavior of Cu-3Ti-3Ni-0.5Si alloy after thermomechanical processing were investigated by light microscope (LM), scanning electron microscope (SEM), electron backscattering diffraction (EBSD), and transmission electron microscope (TEM). The results show that the as-cast Cu-3Ti-3Ni-0.5Si alloy consists of NiTi, Ni3Si, Ni2Si phases and Cu matrix, and the phase transformation occurs twice during the cooling process. Moreover, with increase of aging temperature, the precipitates in the Cu-3Ti-3Ni-0.5Si alloy matrix changes from rod-liked morphology to spherical shape, and the sizes and volume fraction of the spherical precipitates increase progressively. Furthermore, the number of the recrystallization grain increases with increase of the aging temperature, thus leading to decrease on the grain size. In addition, the fraction of low angle grain boundaries decreases, whereas the fraction of high angle grain boundary increases with increase of aging temperature

The shear capacity of reinforced beam concrete was designed to resist the stirrup reinforcement, Vs, and by the concrete itself, Vc. Previous studies of geopolymer concrete show the mechanical properties of this proposed green concrete, yet the structural investigation is infrequently investigated. These studies mostly observed the impact of using alternative binder resources that affect the workability, setting time, compressive strength, split tensile strength, and drying shrinkage. Therefore, this study aims to observe the structural behavior of geopolymer concrete, precisely its shear capacity. Four geopolymer concrete beam types were designed to have shear failure mode when tested using a Universal Testing Machine by four-point load bending method. The results showed that geopolymer concrete has ductile behavior. Comparison between the Vu value of the test results with Vn calculation of nominal cross-sectional capacity according to standard concrete rules in an average of 2.11 higher than the nominal capacity conventionally calculated according to SNI. Two models of linear regression equations for concrete Vc values were created to explore this further. It was found that the presence of a constant increases the value of the coefficient of determination by up to 29% for the Vc equation in geopolymer concrete. In addition, cracking patterns observed with the DIC method using GOM Correlate software also showed that all the beam specimens had failure both in flexure and shear, even though they all are designed
in a shear failure state.

This article is primarily concerned with the turning of Udimet L-605 alloy, which is crucial for a variety of applications, including the production of parts for the automotive, marine, and aircraft sectors. According to the researchers’ recommendation, dry machining was preferable for this machining, and the studies were conducted using a PVD-coated TiAlN-TiN tungsten carbide cutting tool insert. Depth of cut during the machining process is essential for enhancing surface smoothness and reducing tool wear during the turning process. Increased cutting zone temperature brought on by deeper cutting causes increased tool wear and subpar surface finish. In this study, a greater emphasis was placed on the surface morphology for the machined surface’s better and worse surface finishes. The peak and valley profiles created on the machined surface are mostly determined by kurtosis and skewness. The AFM study offered a clear indication of it. The average roughness of 34.77 nm was attained. Nearly 23% tool tip interface temperature was increased with increase of depth of cut.

Vegetable oil-based nano particle is a realistic alternative lubrication used in standard cutting fluids. In this research, turning operations are done on titanium alloy utilizing cemented carbide inserts with nano minimum quantity lubrication (NMQL). A response surface methodology is employed to optimize the machining variables such as cutting speed, feed, and depth of cut to anticipate the ideal surface roughness, cutting forces, and tool tip temperature. Moreover, an experimental study is conducted to evaluate the performance of NMQL with the different machining factors. According to the findings, NMQL with nano aluminum oxide particles added with coconut oil is an effective lubricant which provides lowering cutting forces, surface roughness, and tool wear. The novelty of work is to analyze the machined surface using atomic force microscopy and tool wear patterns were analyzed by using SEM image. Result was compared with the experimental observations. The most ideal solution for the reduction of surface roughness, cutting force, and tool tip temperature was reached at cutting speed of 60 m/min, a feed rate of 0.04 mm/rev, and a depth of cut of 0.05 mm. The greatest roughness value of 1.62 microns obtained.

The primary goal of the research work is, to employ a novel alloy as the skin material of the spaceship as a replacement for Al2024-T3. As a part of this task, a twin rolled Al-Cu wrought alloy, Al2016, was received after being age hardened to T6 condition. This article focuses on the fatigue properties and post-fracture analysis of the Al2016-T6 Alloy. Specimens were prepared according to ASTM E606 standards, and subjected to a rotating-bending fatigue testing machine. As a result, the fatigue property of the Al2016-T6 alloy was determined by Wohler’s curve method, fatigue life prediction through the Basquin Equation, estimation of fatigue strength for infinite fatigue life using the Kohout-Věchet model, and fatigue fractography observations via SEM images. The mode of fracture, the origin of fracture and its mechanism, and the morphology of fractured surfaces were reported after investigation. The outcomes of this alloy were compared and discussed with the properties of the existing skin material of the spacecraft, Al2024-T3.

The construction industry across the world recognizes the need for green, lightweight, and self-compacting materials that are also ecologically benign. Considering this requirement, a recent discovery has indicated that a novel form of concrete, known as foamed concrete (FC), has the potential to reduce structural self-weight. Natural fibres are an excellent option to be added in FC for durability properties improvement and are viewed as a great way to contribute to sustainability. The purpose of this study is to examine the possible utilization of agave cantala-based fibre (AF) in the fabrication of foamed concrete (FC) with the objective of enhancing their durability properties. Low densities FC are prone to serious durability performance degradation hence in this experiment FC of low density of 650 kg/m³ was fabricated and evaluated. Varying weight fractions of AF between 0% to 5% were considered as an additive in FC. The durability parameters that were evaluated included apparent porosity, shrinkage, water absorption and UPV. The experimental findings indicate that incorporating a weight fraction of 3% of AF in FC resulted in the optimal durability characteristics across all the durability measures examined in this study. The inclusion of AF in the combination resulted in a significant decrease in the permeability porosity and water absorption of FC. The presence of FC-AF composites with 4% fibre led to the highest drying shrinkage and UPV value and it performed better than the remaining mixtures.

The recent advancement in the flexible electronic devices have led to a growing interest around conductive polymer composites (CPCs). In this present study, a Linear Low-Density Polyethylene (LLDPE)/Carbon Black (CB) conductive polymer composites and Liquid Silicone Rubber (LSR)/CB conductive polymer composites were made by melt compounding and mixing technique, respectively. The CB serves as conductive filler enhances the performance of LLDPE and LSR by improving their electrical conductivity in the composite systems. In this study, various CB loadings (2 wt.%, 4 wt.%, 6 wt.%, 8 wt.%, and 10 wt.%) had been incorporated within LLDPE and LSR matrices respectively. The CPCs were melt blended using an internal mixer for LLDPE/CB composite, whereas, for LSR/CB composite, a stir mixing technique was employed. In general, additions of CB within LLDPE and LSR matrices had affected the tensile properties of the composites. Nevertheless, it was found that the electrical conductivity for both CPCs were increased with increasing of CB loading. The SEM micrographs revealed the morphology of a fractured CPCs samples. Formation of a network path was believed to be the primary reasons for the increased in electrical conductivity of both composites systems and it was anticipated that the percolation threshold for both CPCs was at 6 wt.% loading.

Wastewater is produced by natural biological processes and a variety of human activities. It is unfit to use directly as the wastewater contains variety of chemicals, contaminants, and pollutants. Wastewater is categorized into two groups of sources which are greywater and blackwater as they differ in contamination levels. Greywater are from showers, baths, whirlpool tubs, washing machines, dishwashers and sinks except for the kitchen sink while the sources of black water are from toilets and kitchen sinks. This study aims to design a Sequence Batch Reactor (SBR) equipped with microalgae microbeads (Botryococcus sp.), to examine the applicability of SBR technology in greywater treatment specifically evaluating the efficiency of SBR performance and to measure the efficiency in removing pollutant greywater of microalgae beads. This was done with the application of SBR to ensure the greywater are properly treated before being discharged.

Advanced numerical models, which predict heterogeneity of microstructural features, are needed to design modern steels with heterogeneous microstructures. Models based on stochastic internal variables meet this requirement. Our stochastic model accounts for the random character of the recrystallization and transfers this randomness into equations describing the evolution of the dislocation populations and the grain size during the hot deformation of steels. The idea of the internal variable model, with the dislocation density and the grain size being stochastic variables, is described in the paper. The material parameters, which influence accuracy and reliability of the model, were identified. They compose shear modulus, lattice friction stress and the mean free pass for dislocations. Numerical test showing influence of these parameters on the identification of the model coefficients were performed and a hint how these parameters should be selected is given. Compression loads and histograms of the grain size measured in the experimental compression tests were used to identify the coefficients in the model. The model was applied to simulations of the industrial process of the hot strip rolling. It was shown that the model can be used to both predictions of the microstructural heterogeneity caused by the stochastic character of microstructure evolution and to the evaluation of the uncertainty of phase composition in the final product. The latter is due to the uncertainty of the boundary conditions.

Repairing tunnels is an essential part of infrastructure upkeep that guarantees commuter safety and the durability of the tunnels. A variety of materials, including cement-based ones like concrete, shotcrete, and mortar, are needed for tunnel repairs. Yet, the hunt for substitute materials has been sparked by the negative environmental effect of cement manufacturing and the accompanying expenses. It has been suggested that geopolymers, a type of materials that develop from the reaction between aluminosilicate minerals and alkali activators, might replace cement-based materials in tunnel restoration. This review paper focuses on evaluating the potential of geopolymers towards applications for tunnel mending because they are a new material with many possible uses.

This study set out to evaluate the hole diameter measuring method used in aircraft seat tracks. The Gage R&R study’s conclusions point to the measuring system’s accuracy and dependability, with the measuring tool serving as the main source of variance. The measurement method works well for production and quality control applications, but regular calibration and maintenance are needed to ensure accurate and consistent results. To reduce any potential operator-introduced variation, regular operator training and assessment are also required. To guarantee the security and effectiveness of the seat track assembly, it is essential to measure the hole diameter of the airplane seat track properly. The study’s findings show that the measuring system can generate precise measurements that are helpful for production and quality management. To establish the precision of the measurement technique, however, more investigation with a greater variety of components is required. To improve the repeatability and reproducibility of the measurement system, the sources of variance should be investigated, and remedial actions should be taken. To make sure the system stays within the permissible range of fluctuation, it is also advised to monitor it throughout time. In conclusion, it is critical to select the proper materials, put them through rigorous testing and certification processes, and constantly inventing and upgrading them to assure the safety and effectiveness of aircraft seat tracks. The seat track hole diameter measurement system is dependable and precise, but to keep it that way, ongoing testing, and evaluation are required.

The aim of this study was to analyze how a periodontal dressing material (COE-PAK, C-P) adapts to the addition of therapeutic agents (allantoin and pyridoxine), especially in terms of its mechanical properties, as these improvements would be very beneficial for those patients going through the healing process. The physical and mechanical characteristics of periodontal dressings have been assessed in a limited number of trials, their clinical application being favorable in some cases, as the surgical periodontal treatment result is thought to be significantly influenced by a variety of factors, one of which is the periodontal dressing. Dental materials and technologies are evolving now faster than ever thanks to the digital era we are living through, but even with these developments the dental medical field, not unlike other medical fields, requires patient-oriented services.

Among the synthetic media used in the industry the most advantageous are the substances resulting as secondary products from the wood or paper processing industry, as carboxymethyl cellulose. Carboxymethyl cellulose dissolved in water is a synthetic quenching environment used in large tempering basin. Due to the dimensions of the quenching basins, the quenching medium is used repeatedly, which leads to its thermal degradation. The degree of modification of the cooling properties and corrosion behavior of aqueous solutions of carboxymethyl cellulose in the thermal range 800-50°C were studied. The changes in the physicochemical properties such as density, pH, specific heat, diffusivity were studied. These characteristics were found to extert major effect on cooling characteristics during tempering. At the same time, the technological characteristics of cooling were also studied. The specific cooling curve of the medium and thermally degraded compared with the characteristics of classic quenching media such as water and heat treatment oil was analyzed. This study provides guidance on maintaining the specific cooling characteristics of a tempering medium after repeated uses.

Geopolymers present a modern low CO₂ footprint alternative of traditional building materials. The reuse of industrial waste or by-products as raw materials could address important ecological problems. The aim of this study is to evaluate the characteristics of mine tailings and coal combustion by-products from Bulgaria as raw materials for the preparation of geopolymers. Three mine tailings and two coal combustion by-products from thermal power stations were characterized. Appropriate validated analytical methods were combined to retrieve detailed information. The studied samples contented relatively high percentage of Al₂O₃ ­(17-21%) and SiO₂ (68-53%), and low concentration of sulfur (0.02-3.5% as SO₃). The alumosilicates, proved by XRD, are expected to show high reactivity in alkaline media, however some less reactive mineral phases were also observed. The aqueous slurry was alkaline pH 8-11, the fly ash contained the highest concentration of components ionized in water solution. Heavy metals content was found to be at micro or trace levels. The copper content was 56-818 mg/kg, Pb 127-2 mg/kg, Cr 1-71 mg/kg. The results showed that the studied mine tailings and fly ash could be used as precursors for geopolymer obtaining after fine adjustment of the technology to account for the specific characteristics of raw materials.

This study investigates the physical, mechanical, and microstructure properties of metakaolin-based porous alkali activated materials (AAM) at different surfactant concentrations as an adsorbent for Cu(II) ion removal. The AAM were synthesized using metakaolin as a precursor and alkali activators. Different surfactant contents ranging from 1 wt.% to 5 wt.% were incorporated into the AAM to enhance their adsorption capacity. The physical properties of the AAM were evaluated by determining their porosity, water absorption and density. The results showed that adding surfactant increased the AAM porosity, leading to higher water absorption. The highest porosity was observed at 3 wt.% surfactant content, indicating the optimal surfactant concentration for promoting a porous structure. The mechanical properties of the AAM were assessed through compressive strength tests. The microstructure analysis using scanning electron microscopy revealed that the AAM exhibited different microstructures depending on the surfactant content. The adsorption capacity and removal efficiency of the AAM for Cu(II) ion removal were determined. With a maximum adsorption capacity of 64.78 mg/g, the porous AAM could adsorb a significant quantity of Cu(II) ions. The outstanding removal efficiency of 97.17% showed the AAM maximum efficiency in removing Cu(II) ions from the solution at an adsorption condition of 25℃, pH 5, an initial concentration at 100 ppm and 60 minutes contact time.

Fibre composite boat construction industry is one of the largest industries that greatly contributes to most of the countries’ economies. Synthetic fibre composite like fibreglass is widely used in making the composite boat hull. The use of fibreglass is costly and it gives a huge effect on the environmental pollution. Nowadays, the green fibres have growth as a demand in hull construction and another industry, because of their light mass, great relative mechanical properties, and more advantages to the fibreglass. The demand for boat from green hybrid materials has gone in striking. Green hybrid materials, like any other composite components used in industries, went through the process of incorporating the reinforcement which is the natural fibre into composite or matrix. All imperfections such as voids, area where resin has unevenly wetted the fibre and misaligned fibres have been determined using non-destructive technique (NDT) namely Infrared Thermal (IR) imaging technique. Then composite specimens were observed via the Scanning Electron Microscopy (SEM). SEM micrograph had been validated the results of IR thermal imaging, impact test and water absorption by following ASTM D6110 and ASTM D570 standard respectively. 45% of the woven kenaf/glass fibre to polyester determines the highest impact properties of 542.22 kJ/m2 and shows the least percentage of moisture absorption at the same time showing the greatest water resistance for the composite material. The defects and interfacial adhesion were observed on the specimen by IR thermal imaging and SEM technique. It was revealed that 45% of the woven kenaf/glass fibre to polyester demonstrated less manufacturing defects and possessed a good interfacial adhesion, while 60% of the woven kenaf/glass fibre to polyester showed the highest manufacturing defects. The consequence of fibre contents had crucial effect towards manufacturing defects and interfacial adhesion of composite testing coupon. As conclusion, the specimens with less manufacturing defects, high impact properties and water absorption had been proposed as hybrid green composite materials for boat hull constructionv

Soil collected from random areas of non-ferrous mines and smelters was studied in order to develop a low-cost but effective method for quantifying arsenic (III), arsenic (V), and total arsenic in contaminated soil. Hydrochloric acid microwave extractions have been used as a method to digest arsenic from soil in a form of solution suitable for speciation. Arsenic (III) is selectively extracted into benzene as arsenic trichloride from a highly concentrated hydrochloric acid solution. This was followed by the arsenic being extracted back into water. The total inorganic content of arsenic (V) can be directly determined by anodic oxidation of a gold screen-printed electrode using electrochemical detection. The amount of available Arsenic (III) in the sample is determined by pre-oxidation with KMnO4 directly added to the electrochemical cell or by directly increasing the pH of the medium. ICP-MS was used to confirm all analyses for the various arsenic species as well as the discovery of total arsenic in the soil. It was discovered that the electrochemical method used allows for the cheap, quick, and selective determination of micro amounts of arsenic forms in contaminated soils.

The microstructure-properties relationship of the low-alloy, high-carbon nanostructured bainitic steel obtained by heat treatment, including austenitization and cooling followed by isothermal nanobainitic transformation at 280℃ for 72 h, was investigated. Detailed characterization of the obtained microstructure was performed using light optical, scanning, and transmission electron microscopy. These analyses reveals that the microstructure of tested nanobainitic steel consists of bainitic ferrite lath with an average size of 84 ± 21 nm and retained austenite with two different morphologies: (i) thin films with an average size of 64 ± 19 nm and (ii) blocks with a size of a few micrometers. The carbon concentrations in the film-type retained austenite and blocks of retained austenite were determined through X-ray synchrotron radiation diffraction analysis. The concentrations are 1.81 ± 0.09 wt.% and 1.39 ± 0.06 wt.%, respectively. The total amount of retained austenite in the microstructure is 48.0 ± 1.8 vol.%, and the dominant crystallographic orientation relationships between the microstructure constituents were determined to be Nishiyama-Wassermann. The minor K-S relationship was also recognized from the SEM/EBSD results. Tensile strength of the nanostructured steel was tested, and yield strength was found to be high. At an elongation of 7.2%, the tensile strength reached a significant level, while the average hardness was 490 ± 7 HV.

Intermetallic compounds (IMCs) including transition metals and p-block metals exhibit high resistance to corrosion and oxidation, low density, high conductivity, and magnetic polarizability. In this study, the first-principles calculations method based on Density Functional Theory (DFT) has been used to investigate the structural and electronic properties, charge density distribution, spin polarizability, and magnetic behavior of Cu_(3–x)Mn_xAl (x = 0, 1) intermetallic compounds. Generalized Gradient Approximation (GGA) was employed with Perdew-Burke-Ernzerhof (PBE) exchange-correlation. Calculation of metallic and conductive nature and structural properties was performed simultaneously for all crystal lattices of Cu_(3–x)Mn_xAl (L1₂, D0₃, and Heusler L2₁) with 221-Pm3m, 225-Fm3m space groups. Notably, the study clarifies the stoichiometric similarity and difference between L1₂ and D0₃ type structures by presenting a detailed discussion of the D0₃ structure and its targeted properties for the first time. The lattice constant values obtained by performing various optimizations are in excellent agreement with previously reported experimental and theoretical data. The electron density distribution and population analysis are consistent and reveal the dominant bonding type in each IMC. Furthermore, Spin Polarizability analysis has been carried out to demonstrate the magnetic nature of the Cu₂MnAl (L2₁) Full Heusler alloy upon the addition of the Mn atom.

Ultrasonic melt processing attracts considerable interest from both academic and industrial communities as a promising route improving melt quality. The significance of this problem is predetermined by the matter liquid state problem. In paper the ultrasound absorption and propagation speed vS temperature are measured using multiple groups of samples, each group heated to a different temperature. This paper summaries the results on the evaluation of ultrasound absorption and the propagation speed, for calculating the ultrasound propagation speed in solutions, studies of the nucleation, growth and fragmentation of particles in liquid melts. It has been proven that melts with semiconductor properties are micro-inhomogeneous due to the existence of clusters in their atomic matrix. These results provide valuable new insights and knowledge that are essential for upscaling ultrasonic melt processing to industrial level.

Due to their excellent corrosion resistance and high specific strength, Ti alloys are widely used in shipboard aircraft structures. However, their low wear resistance limits further applications. In this study, wear-resistant tungsten carbide (WC) coatings were applied to TC4 alloy using electro-spark deposition (ESD), and the processing parameters were optimized through orthogonal tes­ting. The effects of ESD processing parameters on the surface morphology of the wear-resistant WC coating were also investigated. The results showed that output voltage, deposition frequency, and electrode speed significantly influenced coating morphology. A relatively flat and uniform coating on the titanium alloy surface was achieved with WC coatings prepared under an output voltage of 120 V, deposition frequency of 120 Hz, and electrode speed of 350 r.

The evaluation of the mechanical properties of post-fire high-strength steel welds, particularly for secondary applications in medium and large infrastructure, is of critical importance in engineering. This study investigates Q690 high-strength steel welds subjected to heat treatment at 300°C, 500°C, 700°C, and 800°C for 20 minutes, followed by air cooling. Electrochemical hydrogen charging, uniaxial tensile testing, and fracture morphology analysis were employed to examine the mechanical properties of these welded components after fire exposure. The effects of hydrogen embrittlement on the mechanical properties and fracture modes of Q690 welds were analyzed, and a hydrogen embrittlement sensitivity index for the welding joints was proposed. The results of the study show that the heat treatment temperature has a significant effect on the hydrogen embrittlement susceptibility of welded structural components. Higher heat treatment temperatures and longer hydrogen charging times lead to a decrease in the mechanical properties of the material, which is characterised by a flatter and smoother macroscopic fracture surface, while the microscopic fracture pattern is characterised by micro-voids. Hydrogen-induced deformation leads to the accumulation of structural defects, such as micro-inhomogeneities and micro-voids, due to increased hydrogen concentrations. Consequently, the material’s resistance to brittle failure is diminished.