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Given the functional and aesthetic quality expected from concrete surfaces, this study investigated the influence of different formwork materials on their surface density, porosity, voids, and elementary chemical composition by relying on X-ray Microtomography (μCT), Scanning Electronic Microscopy (SEM), and Energy Dispersive X-ray Spectroscopy (EDS). The formwork materials assessed were galvanized steel, regular plywood (pink), marine plywood, polyvinyl chloride (PVC), and silicone. μCT showed that distinct formwork affected the surface density of the concrete. In this case, specimens cast within silicone and marine plywood had similar pore volumes although different pore sizes, whereas PVC led to the highest pore volume with small pore sizes. Galvanized steel and regular plywood resulted in similar porosity. SEM showed that the concrete surfaces produced with marine plywood formwork had the highest void content. EDS identified surface products resulting from the contact of concrete with the different formwork materials, suggesting the potential migration of chemical elements. This research significantly contributes to optimizing formwork material selection and enhancing concrete quality and durability. Moreover, it establishes a foundation for further investigations into how formwork materials affect concrete surfaces and the pathological manifestations potentially arising from the molding process. [ABSTRACT FROM AUTHOR]

Two series of non-hydrogenated diamond-like carbon (DLC) films and molybdenum doped diamond-like carbon (Mo-DLC) films were grown on the silicon substrate using direct current magnetron sputtering. The influence of molybdenum doping (between 6.3 and 11.9 at.% of Mo), as well as the deposited temperature (between 185 and 235 °C) on the surface morphology, elemental composition, bonding microstructure, friction force, and nanohardness of the films, were characterized by atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDX), Raman spectroscopy, and a nanoindenter. It was found that the increase in the metal dopant concentration led to a higher metallicity and graphitization of the DLC films. The surface roughness and sp3/sp2 ratio were obtained as a function of the Mo concentration and formation temperature. The nanohardness of DLC films was improved by up to 75% with the addition of Mo. Meanwhile, the reduction in the deposition temperature decreased the nanohardness of the DLC films. The friction coefficient of the DLC films was slightly reduced with addition of the molybdenum. [ABSTRACT FROM AUTHOR]

This paper investigates durability related properties of concretes containing copper heap leach residue (CHLR) as partial replacement of natural fine and coarse aggregates. The use of CHLR as aggregates in concretes promotes the reduction of the dependance on natural aggregates, upcycling of the waste as aggregates and the reduction of carbon footprint associated with natural aggregate productions. In this study, CHLR was washed, dried, and sieved to separate fine aggregate and coarse aggregate, and concretes were prepared with a cement content of 400 kg/m3 and water-cement ratio of 0.435 by replacing 25-75% natural fine and coarse aggregates. The concrete containing 50% CHLR as a partial replacement of natural CA and FA gained compressive strength of 52.9 and 54.0 MPa; drying shrinkage of 662 and 538 με; volume of permeable voids of 6.2 and 5.7%; 1485 and 2640 coulomb of charge passed in chloride permeability; and primary sorptivity coefficients of 4.0 × 10−3 and 4.3 × 10−3 mm/sec0.5 at 180 days, respectively. In contrast, these properties for the control specimens at the same age were 59.1 MPa, 394 με, 5.19%, 1280 coulomb, and 2.5 × 10−3 mm/sec0.5, respectively. The compressive strength and durability aspects declined in concretes using 75% CHLR coarse and fine aggregates. Existing analytical models for durability related properties of concrete containing natural aggregates are compared to that of the concretes using CHLR. Finally, backscattered electron images coupled with energy dispersive x-ray spectroscopy of the CHLR concretes were analyzed to understand the pore refinement, interfacial transition zones, microcracks, and hydration products influencing the durability aspects. [ABSTRACT FROM AUTHOR]

This Study is focused on suitability of industrial wastes in cement stabilized soil. The investigation is based on Unconfined compressive strength (UCS) tests. Experimental work is carried out to compare the UCS of cement stabilized soil specimens with different proportion of industrial wastes like Iron ore tailing, Quarry dust, Fly ash and Bagasse ash. The mix proportion is designed such that clay content is maintained at 10.5% for fine grained soil and density of 17.5 kN/m³. It is observed that the mix comprising industrial wastes and fiber have improved the mechanical properties compared to cement stabilized soil. Fiber addition has improved post peak behavior of soil specimen. The Scanning Electron Microscopy (SEM) microstructure images depict soil particle flocculation, leading to an increase in compressive strength and Energy Dispersive X-ray Spectroscopy (EDS) studies suggest the use of industrial wastes with natural soil helps in strengthening of soil cement stabilization, as well as to minimize the environmental pollution. [ABSTRACT FROM AUTHOR]

The surface state of heatproof specimens of nickel-based СrNi73MoTiAlNb alloy after both wire electroerosion cutting (WEEC) with different applied energies and finishing high-frequency mechanical impact (HFMI) treatment by an ultrasonic tool is analysed. Using an optical interferometry and scanning electron microscopy, the peculiarities of the formed surface topography and roughness are investigated, and using x-ray diffraction analysis and energy dispersive spectroscopy, the structure, chemical and phase compositions of the surface layers are investigated. In the case of the WEEC using brass wire, the surface microalloying is revealed that is not observed, when molybdenum wire is used for WEEC. This effect determines the changes in mechanical properties or their absence, respectively. Instrumented indentation shows that the thermal exposure under WEEC and finishing HFMI modification result in the surface-layers' hardening, while the microalloying detected under high-energy WEEC leads to a hardness decrease. As established, the HFMI surface modification provides a reduction in the surface-roughness parameters and, accordingly, reduces the probability of the stress concentration on the microrelief and terminates harmful tensile residual stresses. [ABSTRACT FROM AUTHOR]

This paper presents and demonstrates the development of a new lightweight coating for aluminum alloy from a novel multicomponent alloy based on the AlSiMgCu system. The coating was applied using a newly designed approach that combined high velocity oxy-fuel (HVOF) and plasma spraying processes. This hybrid technique enables the deposition of coatings with enhanced performance characteristics. The optical microscopy (OM) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM + EDS) revealed a strong adhesion and compaction between the multicomponent coating and the A6061 substrate. The new coating improved hardness by 50% and increased electrical conductivity by approximately 3.3 times compared to the as-cast alloy. Corrosion tests showed a lower corrosion rate, comparable to thermally treated A6061 alloy. Tribological tests indicated over 20% reduction in friction and over 50% reduction in wear rate. This suggests that multicomponent aluminum coatings could improve automotive and parts in contact with hydrogen by enhancing hydrogen fragilization resistance, corrosion resistance, electrical conductivity, and wear properties, with further optimization of thermal spraying potentially boosting performance even further. [ABSTRACT FROM AUTHOR]

Ni+W coating gained significant attention for designing metal parts, hydraulic cylinders, agricultural rods, and agricultural pumps because of their excellent resistance to wear and corrosion. In this study, Ni+W combined with SiC nanocoatings are successfully prepared on mild steel by utilizing the pulse electrodeposition strategy. The atomic force microscopy, scanning electron microscopy, x-ray diffractometer, energy dispersive x-Ray spectroscopy (EDX), friction wear test, and hardness tester were utilized to further investigate the surface morphology, phase structure, wear properties and hardness of Ni+W combined with SiC nanocoatings, respectively. The results indicated the ~ 32 nm SiC size in nanocoatings with a 6 g/L concentration of electrolyte. The Ni+W combined with SiC nanocoatings deposited at a SiC concentration of 6 g/L had a dense and smooth surface with a depression depth and a bump height of 76.3 nm and 106.6 nm, respectively. The result demonstrates that an uniform and smooth Ni+W combined with SiC nanocoating can be prefabricated by using appropriate plating parameters. The diffraction angles of 41.1, 51.9, and 71.1° correspond to the three diffraction peaks of the Ni+W combined with SiC nanocoatings fabricated at 3 g/L SiC concentration, which are the sharpest of all nanocoatings, corresponding to the (111), (200) and (220) planes of the Ni-W grains, respectively. Moreover, the minimum values of wear depth and wear width of Ni+W combined with SiC nanocoatings fabricated at a SiC concentration of 3 g/L were separately 33.1 μm and 5.6 mm. There are fine scratches and some shallowness on the surface of the Ni+W combined with SiC nanocoatings deposited at SiC concentration of 6 g/L, which indicates the outstanding tribological properties of the nanocoatings. Furthermore, there are Si, Ni, O and C elements present on the surface of the worn Ni+W combined with SiC nanocoatings observed by EDX results. [ABSTRACT FROM AUTHOR]

High strength low alloy steels which are having excellent corrosion-resistant properties are called corten steels. In the present investigation, 3 mm thick ASTM A242 Corten steel sheets were welded together using the cold metal transfer (CMT) method based on two welding controllable parameters like welding current and welding speed. The controllable input parameters like welding current and welding speed have been altered to produce joints that have no flaws and a complete depth of weld penetration. The evaluation of the microstructure and weld geometry was performed for the cold metal transfer welded ASTM A242 sheets using ER70S6 filler wire. The experimental design of welding parameters was developed using an orthogonal array of full factorial design. The dominance of acicular ferrite microstructure is visible in the fusion zone. Results from Energy Dispersive x-Ray Analysis (EDAX) show that manganese content is higher and nickel concentration is lower in the weld fusion region. The fusion zone of the CMT welded specimen has the greatest hardness, which was measured at 270.2 HV. Due to the formation of acicular and bainite microstructure in the welding seam, the tensile properties at room temperature (RT) were found to be 589.79 and 405.63 MPa, accordingly. Bend tests additionally confirmed the satisfactory ductility of the welded joint. [ABSTRACT FROM AUTHOR]

Highly dense high entropy diboride (Ti 0.2 Zr 0.2 Hf 0.2 Nb 0.2 Ta 0.2)B 2 -SiC composites with different β-SiC content (5, 10, 15, 20 and 25 vol%) were prepared by Spark Plasma Sintering (SPS) at 1900 °C. High-purity high entropy diboride (HEB) powder was synthesized using boro/carbothermal reduction of oxide precursors at 1800 °C. X-ray diffraction patterns of the synthesized powders and sintered compacts of HEB showed a single solid solution with hexagonal AlB 2 structure without any residual oxide impurities. Energy Dispersive X-ray Spectroscopy (EDS) mapping results indicated the uniform elemental distribution of transition metals in the HEB phase. The addition of SiC improved the densification of HEB-SiC composites. The composite with 20 vol% SiC exhibited a unique combination of mechanical properties, such as superior Vickers hardness (22.28 ± 0.25 GPa), flexural strength (750.21 ± 43.23 MPa), indentation fracture toughness (4.12 ± 0.2 MPa.m1/2), Young's modulus (495.3 ± 0.3 GPa) and dynamic oxidation resistance (0.02 mg.cm−2.s−1). [ABSTRACT FROM AUTHOR]

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Pedipalps – chelate 'pincers' as the second pair of prosomal appendages – are a striking feature of scorpions and are employed in varied biological functions. Despite the distinctive morphology and ecological importance of these appendages, their anatomy remains underexplored. To rectify this, we examined the pedipalps of the Australian black rock scorpion, Urodacus manicatus , using a multifaceted approach consisting of microcomputed tomography, scanning electron microscopy, energy dispersive X-ray spectroscopy, and live pinch force measurements. In doing so, we document the following aspects of the pedipalps: (1) the musculature in three dimensions; (2) the cuticular microstructure, focusing on the chelae (tibial and tarsal podomeres); (3) the elemental construction of the chelae teeth; and (4) the chelae pinch force. We recognise 25 muscle groups in U. manicatus pedipalps, substantially more than previously documented in scorpions. The cuticular microstructure – endo-, meso-, and exocuticle – of U. manicatus pedipalps is shown to be similar to other scorpions and that mesocuticle reinforces the chelae for predation and burrowing. Elemental mapping of the chelae teeth highlights enrichment in calcium, chlorine, nickel, phosphorus, potassium, sodium, vanadium, and zinc, with a marked lack of carbon. These elements reinforce the teeth, increasing robustness to better enable prey capture and incapacitation. Finally, the pinch force data demonstrate that U. manicatus can exert high pinch forces (4.1 N), further highlighting the application of chelae in subduing prey, as opposed to holding prey for envenomation. We demonstrate that U. manicatus has an array of adaptions for functioning as a sit-and-wait predator that primarily uses highly reinforced chelae to process prey. [ABSTRACT FROM AUTHOR]

The present research assists in resolving the issues allied with the disposal of industrial solid wastes/industrial by-products (IBPs) by developing sustainable IBPs based cement mortars. The applicability of IBPs as a feasible alternative to river sand in cement mortar has been evaluated by investigating the synergy among the ingredients, resulting engineering properties and microstructural developments at early and late curing ages. The study could effectively substitute 30% volume of river sand with bottom ash and 50% in the case of slag sand mortars. The experimental outcomes disclose that the practice of IBPs as fine aggregate enhances the engineering properties of mortar and the optimum replacement level lies at 10% and 40% usage of bottom ash and slag sand, respectively. The advanced characterization studies and particle packing density illustrate the refinement of pores by void filing action and accumulation of additional hydration products through secondary hydration reactions. The consumption of portlandite followed by increased hydration products formation observed through thermogravimetric analysis, X-ray diffraction analysis and energy dispersive X-ray spectroscopy that confirmed the contribution of finer fractions of IBPs to secondary hydration reactions. This constructive development was also observed from the lowering of wavenumber corresponding to Si–O–Si/Al vibration bands in Fourier transform infrared spectroscopy spectra. The improved microstructure resulted in enhancing the compressive strength by 9.01% and 18.18% in optimized bottom ash and slag sand mortars, respectively at the curing age of 120 days. Similarly, the water absorption reduced by 1.03% and 1.24% in bottom ash and slag sand mortars, respectively. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this work is to study the effect of sintering modes, especially the sintering temperature, on the crystal lattice parameters and the morphology of the ZrO2-nY2O3 (n = 3-8 mol%) ceramic microstructure components in relation to corresponding fracture micromechanisms. Design/methodology/approach: The series of ZrO2-nY2O3 (n = 3-8 mol%) ceramics were sintered in an argon atmosphere at temperatures 1450°C, 1500°C, 1550°C, and 1600°C. The cross-sectional surfaces of samples were prepared for microstructure analysis using a grinding and polishing Struers Tegramin machine. Young's ceramics modulus values were determined using an ultrasonic flaw detector Panametrics EPOCH III 2300. The samples' density and porosity were determined by the Archimedes' method. Scanning electron microscopes Hitachi SU3900 and Carl Zeiss EVO-40XVP were used to analyse the microstructure and fracture surface morphology of samples. For estimating chemical compositions in an energy-dispersive X-ray spectroscopy mode, an INCA ENERGY 350 spectrometer was utilized. Microhardness measurement was performed on a NOVOTEST TC-MKB1 microhardness tester. The fracture toughness of the material was estimated using a single-edge notch beam (SENB) test and the Vickers indentation test. Both the flexural strength and SENB tests were performed under threepoint bending using a UIT STM 050 test machine. All mechanical tests were carried out in air at a temperature of 20°C. Findings: Optimal sintering modes for a variety of YSZ ceramic compositions are found, taking into account the combined effect of the sintering temperature and a percentage of Y2O3, which resulted in a specified balance of cubic, tetragonal, and monoclinic zirconia phases, an optimal microstructure features, and the implementation of high-energy fracture micromechanisms responsible for high strength and fracture toughness of YSZ ceramics. Research limitations/implications: To study the behaviour of YSZ ceramics in the operating atmosphere, their microhardness, flexural strength, and fracture toughness should be evaluated under the operating temperature and pressure conditions. Practical implications: Based on the research performed, it is possible to design the microstructure of YSZ ceramic with the necessary physical and mechanical properties to provide high reliability of ceramic products in various industry branches. Originality/value: The balance of cubic, tetragonal, and monoclinic zirconia phases, as well as the crystal lattice parameters change, was determined for YSZ ceramics stabilized with the various amounts of yttria, and it was linked to their mechanical behaviour; the Vickers indentation method and SENB method were used to estimate crack growth resistance of YSZ ceramics, and an appropriate fracture micromechanism was found. [ABSTRACT FROM AUTHOR]

Dirinaria picta is a lichen species known for its tolerance to air pollution and its ability to accumulate pollutants in its thallus, making it a suitable bioindicator in urban areas. This study aims to assess the response of lichens to air pollution by examining their morphological characteristics, analyzing the presence of magnetic grains, and identifying the origin of elements in their tissues. Samples were collected from three locations in Bandung area which represent polluted areas, namely Juanda Street (JD) and Kebon Kawung (KK), and Padalarang Street (PD) and one location which represent as a control area with low pollution levels, namely Curug Cimahi (CC). Lichen microstructure scanning was performed using a Scanning Electron Microscope (SEM), and the presence of elements was detected through Energy Dispersive X-ray Spectroscopy (EDS). The SEM analysis revealed that samples from areas with higher air pollution levels exhibited obvious damage to their thallus, characterized by a more porous structure and the presence of cuboidal particles. Conversely, samples from control area showed a more compact structure. The EDS observations identified 14 elements present in the lichen tissues, ranked in descending order of abundance: C>Ca>O>Pb>Cu>Mn>Zn>Fe>Cr>Al>Cl>Se>Cd>K. The composition and quantity of these elements in lichen tissues were influenced by the level of air pollution generated by the number of vehicles passing through the area. The more vehicles, the higher the level of air pollution, resulting in greater stress for the D. picta population. [ABSTRACT FROM AUTHOR]

CTAB and PVP-capped CdS microstructures have been synthesized hydrothermally along with uncapped CdS microstructure and the effects of CTAB and PVP on morphological and optical properties of synthesized microstructures have been investigated. The X-ray diffraction analysis has elucidated hexagonal phase dominance with the average estimated crystalline size of 9, 9, and 10 nm, respectively, for CTAB and PVP-capped nanocrystalline. HRSEM images confirm the formation of flower-like and popcorn-like morphology decorated with small nanocrystalline for CTAB and PVP-capped CdS microstructure, respectively. The elemental analysis carried out through EDX spectroscopy confirms the presence of Cd and S without any impurities. The UV–Vis spectrum displays a noticeable red shift for all three samples as compared to bulk CdS (2.42 eV). The photoluminescence spectrum demonstrates emission peaks centered at 468, 571, and 598 nm corresponding to the blue, yellow-green, and orange regions, respectively. Furthermore, the vibrational characteristics of the synthesized CdS samples have been also investigated using FTIR spectroscopy. [ABSTRACT FROM AUTHOR]

In this paper, three types of dental alloys often used in practice were investigated, namely: NiCrMoSiVCuFe, NiCrMoSiFeAlMgZn and CuAlNiFeMgZnSi to evaluate the chemical homogeneity. Energy Dispersive X-ray Spectroscopy (EDS) and Backscattered-Electron (BSE) Imaging were used to obtain valid results on the structure and distribution of constituent elements in the investigated alloys. All samples were investigated in 3 different (micron) areas, respectively: a central area and two marginal areas. The EDS investigations followed the identification of the spectral lines, respectively the irrefutable highlighting of the composition of the sample and, subsequently, the distributions of the identified elements in the specified areas to be compared. The mapping distributions of the elements can reveal local homogeneity/heterogeneity (in bottle heterogeneity) and homogeneity at the sample (implant) level (between bottles heterogeneity). The microstructural inhomogeneity resulting from the formation of compounds in the grain boundaries is primary and determines, therefore, elemental or chemical heterogeneity. [ABSTRACT FROM AUTHOR]

Fly-ash-based geopolymer pastes with the addition of expanded vermiculite (EV) powder were synthesised and their microstructure, compressive strength, setting time, moisture control, extent of efflorescence and thermal conductivity were studied. It was found that the addition of EV resulted in an increase in the standard-consistency water consumption and setting times. As a consequence, excessive addition of EV resulted in a larger amount of harmful pores, which was detrimental for the compressive strength of the paste. However, geopolymer pastes with an appropriate amount of EV (2–7 wt%) showed a slight increase in compressive strength because of the filler effect. Mg2+ and Fe3+ diffused from the EV interlayers through ion exchange between the EV and the geopolymer, and participated in geopolymerisation. This was reflected by the formation of N-(M)-A-(F)-S-H, as evidenced by scanning electron microscopy with energy dispersive X-ray spectroscopy and Fourier-transform infrared spectroscopy. In addition, Na+/Mg2+ or Na+/Fe3+ ion exchange reduced the mobility of Na+ the ions and therefore decreased the extent of efflorescence. Moreover, EV addition favoured an improvement in moisture content and the thermal conductivity properties of the geopolymer paste. [ABSTRACT FROM AUTHOR]

In the present paper, microstructural changes in two alloys, IN617 and DMV617 mod, after 5 h and 1000 h of aging at 700 °C were investigated using scanning transmission electron microscopy. The mechanical properties of the samples were evaluated using hardness tests. Precipitates were identified using energy-dispersive X-ray spectroscopy analysis. After long-term aging, intensive precipitation of the M23C6 carbides and γ′ intermetallic phase in the microstructure of alloys was observed. In the IN617 alloy, continuous layers of M23C6 carbides along the grain boundaries after long-term aging were observed. The minor addition of boron to the DMV617 mod alloy is advantageous in microstructure formation during long-term aging because it decreases the agglomeration of M23C6 at the grain boundaries. [ABSTRACT FROM AUTHOR]

In this study, the changes in the phase and microstructure of alkali-activated slag (AAS) in ultralow-temperature environments (−170°C) was experimentally studied by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric (TG), scanning electron microscopy energy dispersive X-ray spectroscopy (SEM-EDS), Si29 magic-angle spinning nuclear magnetic resonance (MAS NMR), and pore structure. The results show that as the modulus of water glass increased, the mass loss of AAS after the ultralow-temperature freeze–thaw cycles (ULT-FTC) decreased, the freeze–thaw resistance increased. The ULT-FTC caused the internal structure of the AAS samples using different activators to slip and rearrange. Partial calcium-(alumina)-silicate-hydrate gel [C─ (A)─ S─ H] gel was decalcified. The gel structure formed using 2.0 M water glass as the activator was the most stable. The dense structure with a lower Ca/Si ratio enables the AAS to maintain a relatively stable microstructure after undergoing ULT-FTC. [ABSTRACT FROM AUTHOR]

This study explored the impact of sintering temperature variations on the synthesis and characteristics of mullite ceramics derived from a composite blend of kaolinite clay, silica (silicon dioxide), and feldspar. Sintering temperatures ranging from 1100 to 1200 °C were systematically examined to analyze alterations in shrinkage, density, microstructure, elemental composition, and phase formation. The study revealed that an increase in sintering temperature led to decreased shrinkage due to improved particle packing and reduced porosity. Ceramic density showed a direct relation with sintering temperature, reaching the optimal density at 1175 °C and indicating efficient particle packing and compaction. Analysis through field emission scanning electron microscopy (FESEM) provided insights into microstructural changes, including alterations in grain morphology, porosity, and connectivity. Energy dispersive X-ray spectroscopy (EDS) clarified element distribution within the microstructure, offering valuable information on compositional variations. X-ray diffraction (XRD) examinations unveiled temperature-dependent phase transformations, which confirmed the successful formation of mullite during the sintering process. A sintering temperature of 1175 °C yielded the optimal ceramic quality and cost-effectiveness for high-temperature heating processes. [ABSTRACT FROM AUTHOR]

Utilization of ultrafine supplementary cementitious materials (SCMs) instead of ordinary ones has shown great potential to enhance the strength development of concrete mixtures. Replacing large amounts of portland cement with ultrafine SCMs, however, may not be feasible due to their negative effect on the water demand of concrete, and extra cost and energy consumption associated with the ultrafine grinding of SCMs. It is therefore important to explore practical methods for efficient use of ultrafine SCMs in producing low portland cement content concretes. To achieve this goal, the current study focused on the use of ultrafine granulated blast furnace slag (GBFS) in combination with a commercial one to replace 30%, 40%, and 50% by weight of portland cement in preparing mortar samples. The compressive strength of the mortars was measured at different ages ranging from 1 to 91 days. Cement paste samples with modified (combination of ultrafine and commercial) and commercial GBFS were also prepared and tested by the isothermal calorimetry, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM/EDS) techniques. The results showed that the samples with 30% and 40% by weight modified GBFS as portland cement replacement had higher compressive strength compared with those made with the same amount of commercial GBFS or 100% by weight portland cement at all the testing ages. The microstructural analyses indicated increased calcium hydroxide consumption and higher reaction degree of clinker phases after 1 day of hydration for the sample incorporating 40% by weight modified GBFS compared with that with the same amount of commercial one, resulting in the superior compressive strength of this sample at such an early age of hydration. [ABSTRACT FROM AUTHOR]

As global urbanization flourishes, the adverse effects on the environment also incredibly increase. This urbanization leads to the evolution of construction and building materials. To meet the requirements of eco-balanced construction materials without compromising their original properties, many evolutions of concrete are in practice nowadays. One such evolution of concrete is geopolymer concrete. The objective of the current study is to produce high-strength geopolymer concrete using ground granulated blast furnace slag (GGBS), metakaolin (MK), and nano-silica (NS) in ambient-cured conditions. The influence of nano-silica in the geopolymer concrete is evaluated by workability, setting time, mechanical strength, durability properties, and microstructural analyses, which include scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and correlation analysis. In this research, the effect of nano-silica on formulating the equation for modulus of elasticity was determined. Nano-silica was replaced at a percentage of 1, 2, and 3% of the binder material. It is summarized that the molar ratios and properties of the precursor materials are the defining factors in altering the systems of geopolymer concrete. The highest strength of 89.4 MPa at 28 days of ambient-cured concrete with outstanding durability performance was achieved. [ABSTRACT FROM AUTHOR]

One of the most promising applications of FeNiCoCrMoAl-based high-entropy alloy is the fabrication of protective coatings. In this work, gas-atomized powder of FeNiCoCrMo0.5Al1.3 composition was deposited via high-velocity oxygen fuel spraying. It was shown that in-flight oxidation of the powder influences the coating's phase composition and properties. Powder oxidation and phase transformations were studied under HVOF deposition, and during continuous heating and prolonged isothermal annealing at 800 °C. Optical and scanning electron microscopy observation, energy dispersive X-ray analysis, X-ray diffraction analysis, thermogravimetric analysis, differential thermal analysis, and microhardness tests were used for study. In a gas-atomized state, the powder consisted of BCC supersaturated solid solution. The high rate of heating and cooling and high oxygen concentration during spraying led to oxidation development prior to decomposition of the supersaturated solid solution. Depleted Al layers of BCC transferred to the FCC phase. An increase in the spraying distance resulted in an increase in α-Al2O3 content; however, higher oxide content does not result in a higher microhardness. In contrast, under annealing, the supersaturated BCC solid solution decomposition occurs earlier than pronounced oxidation, which leads to considerable strengthening to 910 HV. [ABSTRACT FROM AUTHOR]

Utilizing reactive DC magnetron sputtering method, TiN coatings were deposited on the silicon substrates at different nitrogen flows and powers. A study of the X-ray phase composition of the coatings was carried out. The stoichiometric composition of the coatings was determined using energy dispersive x-ray spectroscopy. The structure of the surface, cross-section, and thickness of the coatings were determined using scanning electron (SEM) and atomic force microscopy (AFM). A significant change in the surface structure of TiN coatings was established with changes in deposition power and nitrogen flow. SEM images of cross-sections of all coated samples showed that the formation of coatings occurs in the form of a columnar structure with a perpendicular orientation relative to the silicon substrate. The mechanical properties (elastic modulus E and microhardness H) of TiN coatings of the first group demonstrate a maximum at a nitrogen flow of 3 sccm and are 184 ± 11 GPa and 15.7 ± 1.3 GPa, respectively. In the second group, the values of E and H increase due to a decrease in the size of the structural elements of the coating (grains and crystallites). In the third group, E and H decrease. Microtribological tests were carried out in 4 stages: at a constant load, multi-cycle for 10 and 100 cycles, and with increasing load. The coefficient of friction (CoF) and specific volumetric wear ω depend on the roughness, topology, and mechanical properties of the resulting coatings. Fracture toughness was determined using nanoscratch and depends on the mechanical properties of TiN coatings. Within each group, coatings with the best mechanical and microtribological properties were described: in the first group—TiN coating at 3 sccm (with (29.6 ± 0.1) at.% N), in the second group—TiN coating at 2 sccm (with (40.8 ± 0.2) at.% N), and in the third group—TiN coating at 1 sccm (c (37.3 ± 0.2) at.% N). [ABSTRACT FROM AUTHOR]

This study aims to investigate the combined effect of niobium (Nb) microalloying and austenite grain refinement, using a specific heat treatment cycle, on the microstructure and tribological properties of Armox 500T steel. In this work, Nb addition and thermal cycling were utilized for grain refinement and enhancement of the mechanical properties of Armox 500T alloy, to provide improved protection via lightweight armor steel components with a high strength-to-weight ratio. The kinetics of transformation of the developed Armox alloys were studied using JMATPro version 13.2. The samples were subjected to two austenitizing temperatures, 1000 °C and 1100 °C, followed by 4 min of holding time and three consecutive thermal and rapid-quenching processes from 900 °C to room temperature. Scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX) was employed to analyze the microstructure, which primarily consists of four types of martensite: short and long lath martensite, blocky martensite, and equiaxed martensite. Additionally, a small percentage (not exceeding 3%) of carbide precipitates was observed. The wear characteristics of the investigated alloys were evaluated using a pin-on-disc tribometer. The results demonstrate that alloying with Nb and grain refinement using a thermal cycle significantly reduce the wear rate. [ABSTRACT FROM AUTHOR]

The phase and grain boundary characteristics of recently developed fine-grained dual-phase high-entropy (Ti-Zr-Nb-Hf-Ta)C/(Ti-Zr-Nb-Hf-Ta)B 2 was investigated throughout all the accessible length scales using scanning electron microscopy (SEM), aberration-corrected scanning transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS). The system exhibits relatively homogeneous grain size distribution where the average size is approximately 0.97 µm, with chemical composition (Ti 0.14 Zr 0.2 Nb 0.2 Hf 0.2 Ta 0.26)C + (Ti 0.38 Zr 0.18 Nb 0.22 Hf 0. 115 Ta 0.105)B 2. SEM analyses revealed no micro-crack formation and second – phase segregation at the boundaries or micro-pores at the triple – points. Investigation down to the sub-nanometer scale revealed that the phase and grain boundaries were typically clean and sharp with an indistinct 1 – 1.5 nm thin gradient of metallic elements at boride/boride and carbide/carbide interfaces. The sharp phase and grain boundaries do exhibit elemental enrichment from a trace amount of Fe being incorporated in interstitial positions of carbide and boride grains locally at boride/carbide boundaries or are present in boride and carbide grains in the form of continuous thin layer at boride/boride and carbide/carbide interfaces with the probably origin from starting powders. [ABSTRACT FROM AUTHOR]

The objective of this research was to compare the microstructure and phase composition of wrought and 3D-printed Ti–5Al–3Mo–1V alloys subjected to quenching and aging. The microstructure of as-obtained wrought alloy and samples prepared by wire-feed electron beam additive manufacturing was studied using optical and scanning electron microscopy, as well as transmission electron microscopy. The phase and chemical compositions of wrought and 3D-printed samples were examined using electron backscatter diffraction and energy-dispersive X-ray microanalysis. X-ray diffraction analysis was used to study the martensitic structure of the Ti–5Al–3Mo–1V alloy samples subjected to quenching at temperatures of 900 and 950°C followed by aging at a temperature of 500°C. It was shown that the volume fraction of residual β‑phase in wrought and 3D-printed samples decreased during quenching, and a martensitic orthorhombic α′′-phase appeared. The formation of the α′′-phase in wrought samples after quenching was believed to be associated with the transformation of β → α′′ in bcc solute-lean interlayers. Quenching of the 3D-printed samples, in turn, promoted the formation of α′′-phase in α' laths which undergo α' → β → α" transformation. With the subsequent aging of the wrought and 3D-printed samples, the volume fraction of the α′′-phase decreased. [ABSTRACT FROM AUTHOR]

The current study reports on the long-term structural performance of novel reinforced marine geopolymer concrete beams under accelerated weathering conditions. The study covers the flexural performance of 40 geopolymer concrete beams reinforced with basalt fibre-reinforced polymer (BFRP) bars, including 12 beams under sustained loading when exposed to 3, 6 and 12 months of accelerated marine environment consisting of tidal cycles of seawater at a temperature of 50°C. The experimental results revealed that the novel marine geopolymer concrete reinforced with BFRP bars reported minimal micro- and macro-mechanical degradation compared to geopolymer concrete or ordinary concrete beams under the same exposure environment, with and without sustained loading. The BFRP-reinforced self-compacting geopolymer concrete (SCGC) beams reported 87% residual ultimate load after 12 months of exposure to marine environments, while the sustained loaded BFRP-SCGC beams reported a residual strength of 79%. In addition, microstructural assessment using scanning electron microscopy and energy dispersive X-ray spectroscopy analysis revealed that after 12 months of exposure there was a trace of chloride salts, indicating the chemical ingress over time; however, the impact on structural properties is not distinct. [ABSTRACT FROM AUTHOR]

The objective of this study was to optimize the cooling conditions after solution treatment of the JIS AC4CH aluminum casting alloy, and the effects of the temperature range cooled at 0.5°C/s on the microstructure and mechanical properties were investigated. The temperature range of the cooling and cooling rate were simultaneously adjusted by heating using a high-frequency induction heating apparatus and cooling by blowing air. In particular, cooling at 10°C/s (CR10) was used as the basic cooling rate, with a rate of 0.5°C/s (CR0.5) used for a portion of the temperature range. The scanning electron microscopy (SEM) observations of the specimens after cooling revealed that rod-like precipitates formed in the specimens that were cooled at CR0.5 in the range of 400-250°C. In the specimen that was cooled at CR0.5 from 500 to 450°C, granular or rod-shaped precipitates with a small aspect ratio were observed. From the results of a scanning transmission electron microscopy with energy dispersive X-ray spectroscopy (STEM-EDS) investigation, the former were identified as the Mg2Si intermediate phase, and the latter were composed mainly of Si. An electron probe micro analyzer (EPMA) was used to measure the Mg and Si concentrations in the primary ¡-Al phase. In the case of the temperature range for CR0.5 cooling above 350°C, the Si concentration decreased significantly as the temperature range of CR0.5 cooling increased. Considering the Si concentration distribution and diffusion distance in the primary ¡-Al phase, this decrease in the Si concentration could have been caused by the diffusion of Si atoms to the eutectic region. The 0.2% proof stress and tensile strength values after the artificial aging of a specimen that was cooled at CR0.5 from 400 to 350°C, where a coarse Mg2Si intermediate phase precipitated during cooling, were approximately 10% lower than those of a specimen that was cooled at CR10 over the whole temperature range. [ABSTRACT FROM AUTHOR]

We investigate the microstructures at the interface between the semipolar (101¯3) AlN epilayer and the m-plane (101¯0) sapphire substrate using electron microscopy techniques. The formation of inverted triangular voids in the sapphire substrate side with {112¯0}sapphire sidewalls is observed. Inclined arrowhead features, pointing in the c-axis [0001]AlN direction, are observed in the AlN epilayer side. Lattice-polarity verification confirms that the arrowhead feature relates to the lattice-polarity inversion. Meanwhile, threading dislocations (TDs) propagating to the surface and basal-plane stacking faults (BSFs) lying on the (0001) plane are observed. The lattice-polarity of the final semipolar (101¯3) AlN epilayer is determined to be Al-polar. In addition, an accumulation of Si at the inversion domain boundary (IDB) is found using energy dispersive X-ray spectroscopy (EDS) measurements. The investigation results provide important hints towards understanding and controlling the epilayer growth. [ABSTRACT FROM AUTHOR]

In this study, the relationships among compressive strengths with hydration mechanisms, microstructure characterizations and physical properties of diatomite-substituted cement pastes and mortars were researched. In order to determine the properties of cement pastes and mortars, X–ray diffraction, fourier transforms infrared spectroscopy, thermal analysis, scanning electron microscopy and energy dispersive X-ray spectroscopy techniques and standard cement tests were utilized at 2, 7, 28 and 90 days. The results revealed that portlandite content decreased gradually as a consequence of increasing age and addition of diatomite, and diatomite-substituted cements have high degree of hydration. Furthermore, the diatomite substituted cements had more compact structure by creating more hydration products at 28 and 90 days. This compact structure also positively contributed to the compressive strength of cement mortars at later ages. [ABSTRACT FROM AUTHOR]

This study focuses on the metallurgical characterization of single and multi‐layer martensitic hard surfacing onto non‐standardized low‐chromium alloy steel with a single buttering layer using an automatic submerged arc welding process as a standard reference. The metallurgical properties of hard surfaced samples are examined using an optical microscope, energy dispersive x‐ray spectroscopy, and x‐ray diffractometer. Micro‐Vickers hardness testing is also conducted to analyze and confirm the metallographic results of hard surfacing. The current study finds that the microstructure of each region is influenced by three key factors: chemical composition, heat input, and dilution. The structural type is determined by the chemical composition of materials, heat input influences the structural characteristics in the heat‐affected zone (needle‐shape martensite and tempered martensite), and dilution affects the structural characteristics of the hard surfacing layers (martensite with retained austenite). Comparing multi‐layer hard surfacing to single‐hard surfacing, the hardness values of the heat‐affected zone of the multi‐layer hard surfacing are greatly reduced, while the hardness values of the hard surfacing layers are raised. [ABSTRACT FROM AUTHOR]

The hybrid friction stir channeling (HC) is a recent manufacturing technique, reinforcing the broad range of solutions provided by the technological domain of solid-state friction stir-based welding and processing. HC enables the simultaneous welding of multiple components and the sub-surface channeling within the desired region at the stir zone. HC provides new demanding solutions having free path sub-surface channeling and welding for multi-material components with optimized physical and chemical performances. In the present investigation, a multi-material system consisting of 8 mm thick Al-Mg alloy (AA5083) and 3 mm thick oxygen free copper (Cu-OF) was processed by HC. A specially designed tool consists of the probe's body features that steer materials extraction and the probe's tip features that generate materials mixing was applied to produce sub-surface channel at AA5083, along with its simultaneous welding to Cu-OF material. Visual examination of the AA5083′s surface processed by the shoulder, cross-sectional dimensioning, optical 3D scanning of the internal surfaces of the channel, optical and scanning electron microscopy, energy dispersive X-ray spectroscopy, electron backscatter diffraction and micro-hardness measurements were applied to investigate the results. The successful application of HC to manufacture multi-material Al-Cu component is demonstrated. A large sub-surface quasi rectangular channel with 9.6 mm in width per 3.3 mm in height was produced in the AA5083 rib along with defect free welding to thin Cu-OF plate at just below the channel region multi-material. The resulted sub-surface channel was consisted of unique wall surface features, with non-uniform and non-oriented surface roughness, suitable to activate turbulent fluid flow. The microhardness field depicts a higher-strength domain of the stirred material, at the ceiling of the sub-surface channel in comparison with the base materials. The welding zone comprises a metal matrix composite structure with Al-Cu inter-mixing and a mechanical hooking from Cu into the Al matrix. The metallurgical features of the weld stirred zone were analyzed, with an interpretation of Al-Cu phases, and solid solution of Al and Cu in each other. In this zone, Cu-rich lamellae regions are dispersed within the Al-matrix, presenting thin layers of discontinuous intermetallic compounds. The effective potential of manufacturing multi-material component for applicability in thermal management system is demonstrated. [Display omitted] • Multimaterial Al-Cu Component by Hybrid friction stir Channeling (HC) is presented for the first time. • Sub-superficial channel produced on Al rib along with defect free welding to thin Cu plate in a single manufacturing action. • Unique features of channel's surfaces along with excellent metallurgical bonding of Al-Cu multimaterials is obtained by HC. [ABSTRACT FROM AUTHOR]

The fire resistance of construction materials is an essential part of safety requirements in the construction industry. In this work, experimental investigations were conducted to understand the thermal behaviour, spalling, transfer characteristics, strength, and microstructures of self-cured high-strength plain (HSGC) and steel-fibre-reinforced geopolymer concrete (S–HSGC) under severe fire scenarios with peak temperatures of 275, 560, and 825 °C; the peak was maintained for a period of 120 min after reaching it. Forty-eight standard cylindrical specimens for each mixture were prepared to test and analyse their time–heat response, gradients, visual appearance, spalling, density change, water absorption, and compressive strength before and after fire exposure. Additionally, Scanning Electron Microscopy (SEM) along with Energy Dispersive X-ray Analysis (EDX) were utilised to analyse the internal structures and phase transformations. The thermal analysis showed that no cases of explosive spalling were recorded during sample exposure to various fires, while the used hook-end steel fibres had an influence on the considered test variables. The sample cores almost reached the target heat, and the thermal saturation degree at the peak ranged from 55 to 97%. The experimental findings also revealed slight surface cracking after exposure to 560 °C fires, while the surface cracking was more obvious for specimens exposed to 825 °C. Moreover, the residual compressive strength of the S–HSGC at various fires was noticeably 10.20% higher than that of the HSGC. Also, state-of-the-art research data were used to discuss the prediction model's performance. The SEM and EDX results showed that the self-cured geopolymerization process was effective and successful in producing gels, in addition to the significant phase transformations in microstructures at different fires. This study presented sophisticated data on the behaviour of HSGC and S–HSGC exposed to fires up to 825 °C. [ABSTRACT FROM AUTHOR]

This work evaluates the stabilizing effect of lime addition on the geotechnical, physic-chemical, and microstructural properties of a class A-6 clayey silt. The results obtained show that lime contents of 3–6% lead to changes in grain size that modify the rheology of the material, thus improving the use properties. Compressive strength (3.89–5.95 MPa) and California bearing ratio (CBR 33–54%) increase by 52.95% and 63.63%, respectively. With 6–9% lime, the compressive strength (5.95–4.58 MPa) and CBR (54–41%) decrease by 23% and 24.04%, respectively. The 6% lime content is the point of lime fixation beyond which the mechanical properties of the soil no longer improve. Indeed, the addition of lime reduces the clay fraction (29.45–17.29%) and the silt fraction (45.12–33.05%) by 41.29% and 26.75%, respectively, while the sand fraction (25.43–49.66%) has an increase of 95.28%. The sand content increases considerably and leads to a decrease in the dry density and plasticity of the mix. The increase in sand content leads to a bimodal pore size distribution (micropores and macropores), which results in a flattening of the compaction curves (Proctor) and an increase in the optimum water content. To overcome the negative correlation between compressive strength and strain at failure, the lime-treated pavement layer must be placed on a solid substrate. The results obtained from the effect of lime on the grain size fractions are confirmed by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDX). The disparity in the statistical properties and distribution characteristics of the particle size fraction data is due to the fact that the soil–lime combination does not obey the law of mixtures. [ABSTRACT FROM AUTHOR]

BACKGROUND AND OBJECTIVES: The reduction of fresh water deficit and water-related morbidity is the most important problem of the state's national security. The effective treatment of natural water in industrialized areas from natural and anthropogenic pollutants is the main ecological task. Coagulation is one of the effective methods used to treat water chemically to purify it. Aluminum polyoxychlorides have gained popularity because of their advantages over coagulants--aluminum and iron sulfates. No production of aluminum polyoxychloride occurs in Kazakhstan despite the need for coagulants (the minimum need is assessed at about 11 thousand tons). The work is aimed at theoretical justification and experimental proof of a principally new approach to the development of aluminum polyoxychloride production technology based on activated aluminum alloys containing metal activators, such as gallium, indium, and tin from 0.5 to 5 percent weight. In addition, the goal is solving environmental issues associated with improving the drinking water quality and related to environmental pollution with wastewater. METHODS: The microstructures, phase components, and elemental compositions of alloys and reaction products were studied by scanning electron microscopy/energy dispersive X-ray spectroscopy. The thermal effects of alloys were investigated usin thermogravimetry methods. Oil content in wastewater was determined by spectrophotometry. Oil particle dimensions and wastewater zero potentials were determined using electrophoretic light scattering method and residual turbidity by turbidimetry. Water quality assessment was included in the purified water analysis and comparison with the sanitary and epidemiological standards established for drinking water supply and wastewater intended for water discharge. FINDINGS: The structures and compositions of activated aluminum alloy containing metal activators - gallium, indium, and tin - from 0.5 to 5 weight percent and aluminum polyoxychlorides based on it were studied using modern instrumental methods. The efficiency of the treatment of natural and oilcontaminated wastewater with aluminum polyoxychloride was assessed. The treated water parameters were within the norms established for drinking water supply and wastewater disposal by Sanitary Rules and Norms 2.1.4.559-96. The efficiency of potable water treatment reached 90-99 percent. CONCLUSION: An effective and technologically simple method is developed for producing aluminum polyoxychloride. It involves dissolving an activated alloy in 1-5 percent hydrochloric acid, with an aluminum content of 98.5-85 percent. Alloy processing is carried out at temperatures ranging from 60 to 65 degree celsius. The temperature rises from 20 to 25 degree celsius to the specified optimum without heat supply from the outside due to the interaction among reagents. The process is completed in 2-3 hours. The results confirm that aluminum polyoxychloride is an effective coagulant for drinking and wastewater treatment. The treated water is within the established limits in terms of hydrogen potential, chemical oxygen demand, and turbidity. The water treatment method can be easily implemented. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effects of 1-year water storage and surface treatments on shear bond strength (SBS) of two composite cements bonded to resin matrix CAD-CAM ceramics (RMCs) and on the mechanical properties of RMCs. Materials and Methods: Three types of RMCs were tested: 1. polymer-infiltrated hybrid ceramic (PIHC, Enamic, VITA Zahnfabrik); 2. resin nanoceramic (RNC, Lava Ultimate, 3M Oral Care); and 3. flexible hybrid ceramic (FHC, Cerasmart, GC). One indirect laboratory composite (ILC, Epricord, Kuraray Noritake) was used as control. For each material, 60 plates (14 x 7 x 1 mm) were prepared for the SBS test and submitted to three different surface treatments: following manufacturer's instructions, non-thermal atmospheric plasma application (30 s), and plasma + bonding agent. Two composite cements were tested: RelyX Ultimate (3M Oral Care) and Panavia V5 (Kurarary Noritake). Two resin cylinders (1.5 mm diameter x 1.5 mm height) were bonded to each plate (n = 10), with one tested after 24-h storage in distilled water and the other after 1 year of storage in distilled water. Twenty rectangular bars (12 x 2 x 1 mm) of each indirect material were prepared and submitted to the 3-point flexural test after 24-h or 1-year water storage to determine the elastic modulus (EM) and flexural strength (FS) (n = 10). Fractured samples were also examined with SEM and energy dispersive x-ray spectroscopy (EDS). SBS data were analyzed by four-way ANOVA, and EM and FS data by two-way ANOVA, followed by Tukey's post-hoc test (a = 0.05). Results: Groups treated in accordance with manufacturer's instructions exhibited higher SBS than did plasma and plasma + bonding agent groups for all indirect materials, composite cements, and storage periods tested. In general, RelyX Ultimate displayed higher mean SBS than did Panavia V5, except for some groups of ILC where manufacturer's instructions were followed. After 1-year storage in water, all groups exhibited a significant reduction in SBS, except for some groups that following manufacturer's instructions. ILC showed the lowest values of EM and FS. Among the CAD-CAM materials, FHC exhibited the lowest EM and highest FS means, while PIHC possessed the highest EM and lowest FS means for both storage periods. Conclusions: In general, following the respective manufacturer's instructions yielded the best bond strength results. For most materials, 1-year water storage decreased bond strength of composite cements to RMCs, as well as their FS, while increasing their EM. Microstructure and composition influenced the mechanical properties studied. [ABSTRACT FROM AUTHOR]

The diagnostics of materials, elements and structures after fire exposure are very complicated. Researchers carrying out such diagnostics encounter difficulties at the very beginning, e.g., how to map fire conditions. In this publication, the authors focused on the analysis of the fibre-cement composite used as facade cladding. The fibre-cement boards are construction products used in civil engineering. The fibre-cement boards are characterised by two phases: the matrix phase and the dispersed phase. The analysis of fibre-cement composite was performed using non-destructive methods. The use of non-destructive methods in the future will allow for the analysis of facades after fires without the need to obtain large elements, which will significantly reduce costs while increasing safety. The aim of the work was to determine internal changes in the microstructure of fibre-cement boards after exposure to fire. The degraded samples were compared with reference samples in the evaluation of the microstructure. An analysis was performed using a scanning electron microscope, images of backscattered electrons (BSE) and maps obtained using Energy Dispersive X-ray Spectroscopy (EDX), which allowed conclusions to be drawn. The observed changes were presented in the form of photos showing changes in the composition of the plates, and they were commented on. It should be noted that fire temperatures act destructively, and a number of changes can be observed in the microstructure. The results of the work indicate that, in the future, the use of non-destructive methods will make it possible to assess the degree of degradation of the façade after a fire. [ABSTRACT FROM AUTHOR]

The impact of various heat treatment procedures on microstructure, dislocation density, hardness, tensile characteristics, and impact toughness of P92 steel was examined in the current experiment. The martensitic microstructure and average microhardness of 463 HV 0.2±8 HV 0.2 of the normalized steel were prevalent. A tempering procedure was carried out at 760 °C for a range of 2 hours to 6 hours. Additionally, an X‐ray diffraction examination was carried out, and the results were used to determine the dislocation density. The normalized sample was characterized by a high dislocation density. The dislocation density was decreased by tempering of normalized samples. With an increase in tempering time, the effect of the treatment coarsened the grains, precipitates, and decreased the area fraction of precipitates. After tempering, MX, M23C6, and M7C3 types precipitates were found to have precipitated, according to energy dispersive spectroscopy and x‐ray diffraction research. The ideal tempering period was determined to be 4 hours at a tempering temperature of 760 °C based on the microstructure and mechanical characteristics. Steel that was tempered at 760 °C for 4 hours had a yield strength of 472 MPa, an ultimate tensile strength of 668.02 MPa, and an elongation of 26.05 %, respectively. [ABSTRACT FROM AUTHOR]

Aluminum matrix nanocomposites have been the subject of much attention due to their extraordinary mechanical properties and thermal stability. This research focuses on producing and characterizing an aluminum matrix reinforced with silicon carbide (SiC) nanometric particles. The conventional powder metallurgy route was used to produce the nanocomposites, and the dispersion and mixing process was carried out by ultrasonication. The conditions of the dispersion and the volume fraction of the SiC were evaluated in the production of the nanocomposites. Microstructural characterization was carried out using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD). Mechanical characterization was carried out using hardness and tensile tests. The dispersion agent was investigated, and isopropanol leads to better dispersion with fewer agglomerates. Increasing the volume fraction of the reinforcement improves the hardness of the nanocomposites. However, greater agglomeration of the reinforcement is observed for larger volume fractions. The greatest increase in hardness (77% increase compared to the hardness of the Al matrix) is obtained with 1.0 vol. % of SiC, corresponding to the sample with the best dispersion. The mechanical characterization through tensile tests attests to the effect of the reinforcement on the Al matrix. The main strengthening mechanisms identified were the load transfer, the texture hardening, Orowan strengthening, and the increase in the density of dislocations in the nanocomposites. [ABSTRACT FROM AUTHOR]

This study examined the solidification features and wear of AlSi10Mg(-Ni) alloy samples generated under various conditions. Additions were varied from 0 to 3 wt% Ni while maintaining Si and Mg contents. All samples were directionally solidified (DS) and laser treated using surface laser remelting (LSR). Both DS and LSR samples were characterized by a number of methods, including the following: thermal analysis, optical microscopy, stereomicroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), wear tests, and Vickers hardness. Ranges for cooling rates, dendritic spacing and hardness, respectively, were from 0.4 to 13.3 K/s, from 77 to 388 μm, from 71 to 93 HV for the DS samples and from 4.3 × 104 to 8.7 × 104 K/s, from 1.0 to 2.0 μm, and from 114 to 143 HV for the LSR (100 J/mm2). The solidification kinetics had a large impact on the solidified samples, allowing a representative range of microstructures and morphologies to be examined in terms of wear. The 1% Ni alloy had the highest wear resistance among all the DS samples under slow cooling and the short-term wear test (10 min/0.5 N), while the LSR samples showed similar wear resistances regardless of the Ni content. The uniform dispersions of Si and Al3Ni forming intercellular dense walls at the top of the laser molten pool together with their rod-like morphologies and reduced dendrite spacing of less than 2 μm, improved bonding with the matrix, resulting in higher and more consistent wear resistance of the laser treated surfaces. [ABSTRACT FROM AUTHOR]

In laser-based directed energy deposition (L-DED) of Inconel 718 the microstructure of the fabricated components strongly depends on the applied process parameters and the resulting solidification conditions. Numerous studies have shown that the process parameters deposition speed and laser power have a major influences on microstructural properties, such as dendrite morphology and segregation behavior. This study investigates how changes in these process parameters affect the microstructure and hardness when the line mass, and thus the resulting layer height, are kept constant. This enables the microstructural comparison of geometrically similar specimens that were manufactured with the same number of layers but severely different process parameters. This approach yields the benefit of almost identical geometrical boundary conditions, such as the layer-specific build-height and heat conducting cross section, for all specimens. For microstructural analysis scanning electron microscopy and energy dispersive X-ray spectroscopy were applied and the results evaluated in a quantitative manner. The microstructural features primary dendritic arm spacing, fraction and morphology of precipitated Laves phase as well as the spatially resolved chemical composition were measured along the build-up direction. The occurring cooling rates were calculated based on the primary dendritic arm spacing using semi-empirical models. Three different models used by others researchers were applied and evaluated with respect to their applicability for L-DED. Finally, microhardness measurements were performed for a baseline evaluation of the influence on the materials' mechanical properties. [ABSTRACT FROM AUTHOR]

The corrosion behaviour of the closed-cell aluminium foam made of Al 6101 alloy in different heat regimes such as heat treatment (HT), cryogenic treatment (CT) and cryogenic heat treatment (CHT) are investigated in this research work. The Electrochemical Impedance Spectroscopy (EIS) and DC polarisation are the techniques employed in this research work. The microstructure, surface morphology and composition of the treated foam samples are evaluated using a high-resolution Scanning Electron Microscope (SEM) and Energy Dispersive Analysis of X-rays (EDAX). The polarisation and electrochemical impedance measurements of the CT and HT foam samples reveal appealing results in the corrosion resistance when comparing with untreated foam sample. From the SEM images, it is evident that the deep cryogenic treatment changes the morphology of Al 6101 foam and the formation of the Guinier-Preston (GP) zone increases the density of dislocation. [ABSTRACT FROM AUTHOR]

Purpose: The poor corrosion resistance of the ferrite-pearlite steel limits its application in marine engineering because of the enhanced galvanic effect caused by continuously accumulated cementite. Cr as one principal alloying element is commonly used to improve the corrosion resistance of steels. This paper aims to study the effect of Cr on corrosion behaviors of ferrite-pearlite steels in an acidic environment. Design/methodology/approach: The tested steels were immersed in a simulated solution of 10 Wt.% NaCl with pH 0.85 for 72 h to evaluate the corrosion rate. After the immersion test, the corrosion morphologies and products were tested by scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffraction. Meanwhile, an electrochemical workstation was used to study the electrochemical behaviors of samples. Findings: At the initial corrosion stage, the corrosion rate increased in the sequence of Cr0, Cr0.5 and Cr1 steels, which was because of the competitive effect between the area ratio and the driving force caused by alloyed Cr. However, Cr1 steel exhibited the best corrosion resistance after a 72-h immersion test. This was because the alloyed Cr promoted the formation of protective Fe2O3 and FeCr2O4, which suppressed the preferential dissolution of ferrite and, thus, reduced the accumulation rate of carbides, resulting in the weakened galvanic corrosion. Originality/value: This paper reports the role that Cr plays in the galvanic corrosion of ferrite-pearlite steels, which is important for the engineering application of ferrite-pearlite steels in marine environment. [ABSTRACT FROM AUTHOR]

In the presented work, two multicomponent Cr25Zr25Co20Mo15Si10Y5 and Cr25Co25Zr20Mo15Si10Y5 alloys were produced from bulk chemical elements using the vacuum arc melting technique. X-ray diffraction phase analysis was used to determine the phase composition of the obtained materials. Microstructure analysis included scanning electron microscopy and energy dispersive X-ray spectroscopy techniques. The studies revealed the presence of multi-phase structures in both alloys. Elemental distribution maps confirmed the presence of all six alloying elements in the microstructure. The segregation of chemical elements was also observed. Microhardness measurement revealed that both alloys exhibited microhardness from 832(27) to 933(22) HV1. [ABSTRACT FROM AUTHOR]

The influence of the focusing current of electron beam welding on the nature of the formation of welded joints of aluminium 2219 alloy was investigated. It was established that when the focusing current increases, the width of the face weld grows. And the width of the weld root depends on the real position of the electron beam focus relative to a sharp focus on the metal surface (639 mA). Dependence of the focusing current on the distribution of copper and aluminium in the weld metal was revealed. An increase in the focusing current from 629 to 649 ma led to an increase in the copper content in the interdendritic regions. energy dispersion X-ray analysis showed that the microstructure of the welded joint produced at the focusing current of 629 mA, consists of equiaxial dendrites with embedded small particles, pores and α+θ-Al2cu eutectic, separated in the interdendritic regions. [ABSTRACT FROM AUTHOR]

In this work AlSi nanocomposite coating were deposited by RF magnetron sputtering in Ar/N 2 reactive atmosphere. AlSi alloy target of composition 86:14 wt % have been used to deposit the coating on float glass substrate by varying the deposition time: starting from 0.5 h to 2 h. The substrate temperature and target power were fixed at 250 °C and 100 W respectively. The effect of deposition time on microstructure, mechanical and optical property were studied by usingX-ray Diffraction (XRD), Stylus profiler, Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray Spectroscopy (EDS), Transmission Electron Microscopy (TEM), UV–Visible Spectrometer and Nanoindentation techniques. The XRD shows the formation h-AlN phase for film deposited for 2 h which shows that with increase in deposition time, the film structure changes from amorphous to polycrystalline, the coating deposited for 2 h develops wurtzite-AlN nanocrystalline structure. The thickness of the coating increases with respect to the increasing deposition time which was confirmed from stylus profiler. The FESEM study shows the uneven and randomly oriented grains present in the coating. TEM study confirms the amorphous and polycrystalline nature of the films with low and high thickness respectively. The elemental composition was confirmed by EDS. UV–Visible Spectrometer delivers the optical transparency of the film which is >90% for all the coatings in the visible range spectra. The roughness of the samples was also measured from scanning probe microscope image, which showed average roughness (R ã) value below 2 nm. The maximum hardness obtained is 31 GPa for the coating deposited 2 h with 490 nm thickness, it has an elastic recovery of 92% which suggest its resistance to elasticity as well as plastic deformation. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper presents experimental investigations on epoxy mortar produced using industrial wastes. In some recent studies, coal bottom ash and polyethylene terephthalate (PET) waste have been chosen as a filler to replace sand, and fly ash and silica fume have been chosen as micro fillers for epoxy mortar production; enhanced results in terms of compressive and tensile strengths and durability have been achieved. However, these approaches failed to boost the strength and durability compared to the epoxy steel slag, epoxy sand, epoxy marble dust, and epoxy polyvinyl chloride (PVC) waste. This present research work has investigated the influence of waste filler on the mechanical properties and microstructure of epoxy mortar, produced by using sand and industrial wastes, i.e., steel slag, marble dust, and polyvinyl chloride waste. Based on the composition ratio, the prepared samples of epoxy resin mortar containing 25% epoxy binder (epoxy resin plus epoxy hardener) and 75% filler (1:3) were compared to the cement mortar. However, each specimen of epoxy resin mortar was prepared by mixing with different fillers. The properties such as compressive strength, tensile strength, and microstructural changes were measured using different characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared radiation spectroscopy (FTIR), and scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDX). From the obtained results, it was found that the strength of the specimens increases when blended with steel slag and marble dust, which is attributed to their peak densities and enhanced particle interactions. The XRD, SEM, FTIR, and SEM-EDX analyses showed the formation of calcium, magnesium, and other phases in the microstructure of epoxy resin-based mortars. This resulted in lower water absorption and porosity, as well as improvements in both compressive and tensile strengths. This research can help in understanding the important role of different industrial wastes as feasible fillers in epoxy resin-based composites. [ABSTRACT FROM AUTHOR]

To achieve compact and lightweight power conversion devices, magnetic core materials such as MnZn ferrite are highly desired with low core losses at high frequencies above megahertz. In this work, high-valent Sn4+ ions were doped into MnZn ferrite to manipulate the electromagnetic properties and suppress the high-frequency core losses. The distribution of Sn4+ in MnZn ferrite was investigated by transmission electron microscopy with energy dispersive x-ray analysis, which indicated that most of the substituted Sn4+ ions remained at the grain boundaries rather than dissolving into the lattice, and thus greatly impacted the electromagnetic properties of MnZn ferrite. The initial permeability and saturation induction decreased monotonically with the Sn substitution. The core loss was reduced to 457 kW m−3 at 3 MHz, 30 mT, and 25 °C when the Sn substitution content was 0.003, due to the effective suppression of eddy current loss and residual loss. The sample with a Sn content of 0.003 exhibited excellent overall electromagnetic properties, which could be potentially useful in high-frequency transformers, converters, and power sources. [ABSTRACT FROM AUTHOR]

This article aims to observe the microstructure, mechanical properties, and interface bonding of a 0.35Cr-1.9Ni-0.55Mo alloy deposited on 20Cr steel by wire and arc-based directed energy deposition (WA-DED). For this purpose, different characterization techniques such as an optical microscope, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), and a highresolution X-ray diffractometer were used to analyze the microstructure, chemical composition, and phases of the deposited material. Microhardness and tensile tests were also carried out. The results show that the microstructure of the deposited material is relatively homogeneous, with a slight increase in grain size from the bottom to the top of the deposited part, thus resulting in a slightly decreasing trend in microhardness. However, the ranges of hardness values, i.e., 288 ± 16.78 HV0.1 (in the bottom) to 256 ± 17.04 HV0.1 (in the top), overlap very significantly, and they are not statistically different. The heat-affected zone (HAZ) is the hardest (301 ± 2.70 HV0.1), while the substrate has the lowest microhardness (203 ± 17.64 HV0.1). The tensile strengths of deposited materials are relatively isotropic in both the horizontal (HD) and vertical (VD) directions: UTSVD = 1013 ± 9.29 MPa, USTHD = 985 ± 24.58 MPa, YS(0.2 %)VD = 570 ± 4.51 MPa, and YS(0.2 %)HD = 614 ± 19.66 MPa. The tensile strengths of interface specimens are also comparable to those of the substrate materials (e.g., 951 vs. 972 MPa in UTS), indicating excellent metallurgical bonding between the deposited and substrate materials. The results of this work confirm the efficiency of the WA-DED technique to produce high-quality components in industry. [ABSTRACT FROM AUTHOR]