Science of Sintering is an international Diamond open access journal specializing in the field of science and technology of sintering.
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Nanocomposite CuxS on Flexible Polymers: Raman Study
Flexible polymers modified with copper sulfides have emerged as a novel class of materials, presenting composite structures with remarkable properties suitable for applications in flexible electronics. This study focuses on the deposition of copper sulfide (CuxS) layers onto the surfaces of polyamide and polypropylene through the chemical bath deposition method, employing either 2 or 3 deposition cycles. The objective is to explore the impact of deposition cycles and discern the optimal conditions for the deposition process. Comprehensive analysis of the CuxS thin films entails techniques such as scanning electron microscopy (SEM), Raman spectroscopy, UV-VIS spectroscopy, and X-ray diffraction to shed light on their structural and optical characteristics.
Kinetics of the Crystallization Process of Ferromagnetic Fe65.5Cr4Mo4Ga4P12C5B5.5 Bulk Metallic Glass
Glassy rods of the multicomponent ferromagnetic Fe65.5Cr4Mo4Ga4P12C5B5.5 alloy were prepared by copper-mold casting technique under a protective argon atmosphere with diameters of 1.5 mm and 1.8 mm. As-cast samples were examined by non-isothermal analysis (DSC and DTA) and X-ray diffraction (XRD). The relatively high values for reduced glass transition temperature (Trg = 0.57) and supercooled liquid region width (ΔTx ≈ 60 K) indicate good glass forming ability (GFA) and high thermal stability of the undercooled liquid relative to the crystallization process. The numerous intermetallic compounds during the devitrification process were evolved. Set of three GFA parameters are obtained: α = Tx / Tl = 0.61; γ = Tx / (Tg + Tl) = 0.39; δ = Tx / (Tl – Tg) = 1.41. The Kissinger method was applied to evaluate the apparent activation energy and the frequency factor. The rate constant of the crystallization process is estimated by Arrhenius law. The following values are calculated: Ea = 418.03 kJ/mol; Z = 1.78•1027 min-1; kx = 1.56 min-1 (for 1.5 mm), and Ea = 375.48 kJ/mol; Z = 1.88•1024 min-1; kx = 1.44 min-1 (for 1.8 mm).
Comparison between Transport Properties for H2+ in H2 and H2+ in Ar Gas
In this work we present a cross-sections dataset and transport properties of H2+ in H2 gas and H2+ ions in Ar gas. The ionic charge transfer reactions with molecules are indispensable elementary processes in the modeling of kinetics in terrestrial, industrial, and astrophysical plasma in the detection of dark matter. A Monte Carlo simulation method is applied to accurately calculate transport parameters for the hydrodynamic regime. We discuss new data for H2+ in H2 gas and H2+ ions in Ar gas where the drift velocity, characteristic energy, flux and bulk values of reduced mobility and diffusion coefficients are given as a function of low and moderate reduced electric fields, E/N (E-electric field strength, N-gas density).
Highly Tough and Hard Zirconia-Based Composites Derived from 3Y-TZP and 12Ce-TZP Powders by Co-Doping Approach
Due to their superior physical, chemical, and mechanical properties, 3 moles % yttrium stabilized tetragonal zirconia polycrystalline (3Y-TZP) ceramics are used in dental applications. However, the safe usage of 3Y-TZP is constrained in dental applications by low (or moderate) fracture toughness. Therefore, this research aims to enhance the fracture toughness of 3Y-TZP ceramics by adding 12 mole % cerium-stabilized tetragonal zirconia polycrystalline (12Ce-TZP) counterparts. Here, specimens were densified by pressureless sintering at 1500-1550ºC and 1-2 hours. Relative density (%), Vickers hardness (Hv), indentation fracture toughness (Kıc), and flexural strength (σ) were measured after sintering. X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), and energy dispersive X-ray spectroscopy (EDS) analyses were carried out to clarify the microstructure. Based on overall results, highly tough and hard-sintered composites with sufficient strength can be effortlessly produced by a co-doping approach from different zirconia powders. Specifically, the 25% Y-TZP/75% Ce-TZP composites @1550ºC-1h exhibited Hv: 9.57±0.1 GPa, Kıc:18.26±0.1 MPa.m1/2, and σ: 421±9.2 MPa values. These data presented herein pave the way for producing tailorable structure-property relationships in various ZrO2 ceramic applications, e.g., dental and cutting tools.
Formation of WO₃ Thin Films from RF Sputtered Tungsten Films by Air Annealing: A Cost-Effective Approach
WO3 thin films were prepared by RF sputtering metallic tungsten onto glass substrates, followed by thermal oxidation through annealing in air. This technique is straightforward, cost-efficient, and time-effective, achieving high deposition rates of 16 nm/min on average at 200 W magnetron power for the highly homogeneous W-metallic films. SEM/EDX analysis showed that after annealing at 450ᵒC in air, the RF sputtered 269 nm thick metallic W films with a round grain morphology (~30 nm) turned into 420 nm thick nearly stoichiometric transparent WO3 (tungsten (VI) oxide) film, with a dramatically changed morphology of aggregated crystal rods approximately 1 µm long. XRD and Raman spectroscopy confirmed a biphasic crystal structure, with a dominant monoclinic phase and a minor tetragonal phase. XPS analysis revealed the characteristic W4f7/2 and W4f5/2 electron peaks associated with the W6+ oxidation state, with no evidence of W5+ species, indicating a stoichiometric nature of the WO3 films.
Challenges and Innovative Solutions in Fabrication of Ceramic Matrix Composite for Ultra High-Temperature Application
Ceramic Matrix Composites (CMCs) are transformational materials with outstanding thermal stability, mechanical strength, and resilience to severe conditions, making them important in aerospace, energy, and defence applications. This paper examines the novel approaches and problems of creating CMCs for ultra-high-temperature settings, emphasizing material selection, reinforcing strategies, and advanced production techniques. Recent improvements include using silicon carbide (SiC) and zirconium oxide (ZrO2) as matrix materials and reinforcements, such as continuous fibers and whiskers, to improve performance. Advanced processing methods, such as Polymer Infiltration Pyrolysis (PIP) and Chemical Vapor Infiltration (CVI), provide precise microstructure customization for high-demand applications. Despite these gains, challenges such as oxidation resistance, surface degradation, and cost-effective scaling persist. Integrating non-destructive evaluation techniques and adhering to high-quality standards is essential for boosting reliability. This review emphasizes the promise of CMCs in satisfying critical technological objectives while underlining the need for continuous research into processing advancements and environmental durability to enhance their application in ultra-high-temperature sectors.
Microstructure and Orientation - Dependent Fatigue Performance of Direct Metal Laser Sintered Maraging Steel
The microstructure of maraging steel produced by direct metal laser sintering (DMLS) is influenced by various factors, including parameters of the DMLS process and post-treating methods. This study investigates the effect of build orientation on the microstructure and fatigue behaviour of M300 maraging steel manufactured using DMLS. Microstructural characterization was conducted using light microscopy (LM) and scanning electron microscopy (SEM). The study also involved analysing fracture surfaces using SEM and performing fatigue tests on additively manufactured samples. The research reveals that the presence of inclusions in the specimens has resulted from trapped powder on the edge of the melted pool or from trapped metal oxides. These defects, especially when located near the surface of the specimens, often represent a weak spot and the source of initial cracks.
Hardness, Wear and Thermal Properties of SiC/Carbon Black-Reinforced Al6061 Matrix Composites Produced via Powder Metallurgy
In this study, carbon black (CB) obtained from the pyrolysis of waste tires was used as a reinforcement material. Al6061 alloy, widely utilized in the automotive industry, was selected as the matrix material, while silicon carbide (SiC) was employed as a secondary reinforcement. The study investigated not only the feasibility of using CB as a reinforcement material but also its compatibility with SiC. The mechanically mixed powders were compacted under a pressure of 450 MPa for 1 minute and sintered at 640°C for 360 minutes, producing the composites via the powder metallurgy (P/M) method. Microstructural images and EDS analyses revealed the presence of carbon black within the internal structure, a homogeneous distribution of the reinforcing elements, and the absence of agglomeration. Significant increases in hardness were observed with higher reinforcement content. The hybrid composite reinforced with 5% CB and 7% SiC exhibited a 101.28% increase in hardness compared to the Al6061 alloy. The most substantial reduction in wear rate, 252% relative to the Al6061 alloy, was identified in the composite reinforced with 10% CB. Furthermore, the thermal conductivity of the Al6061 alloy, initially 167 W•m⁻¹•K⁻¹, decreased to 141.5 W•m⁻¹•K⁻¹ with the addition of 7% CB. In conclusion, the addition of CB significantly improved the hardness and wear resistance of the composite while reducing its thermal conductivity.
Analysis of the Qualitative Characteristics of Polo Shirts Made of Cotton and Cotton/Elastane Single Pike Weave Before, During and After 60 Washing Cycles with Commercial Detergents
The qualitative characteristics of T-shirts made of 100% cotton and 95% cotton and 5% elastane were investigated before and after 20, 40 and 60 cycles of washing with commercial detergents. The results of the experimental tests were approximated by a nonlinear model of data fitting, which is in the form of a 9th degree polynomial. This defines the deformation characteristics, which can be used to predict the changes that occur within the structure of the knitwear during stress. The results obtained make it possible to pre-design the intensities of forces to which polo shirts can be subjected without compromising their quality. The results also state that T-shirts with elastane have 12% higher values of bursting strength and higher values of forces at the limit of elasticity compared to pure cotton T-shirts. Cotton T-shirts have 21% higher air permeability and 10% higher water vapor permeability. Cotton T-shirts with elastane have a higher surface mass and stitch density per cm-2 compared to pure cotton T-shirts. Paper shows the qualitative changes of polo shirts during the six-month maintenance cycle and their deformation characteristics. These findings offer valuable insights into the longevity of polo shirts, potentially guiding manufacturers in designing more durable work uniforms.
Characterization and Optical Properties of Cobalt-Doped β-Tricalcium Phosphate Nanoparticles: Microwave Refluxing and High-Temperature Sintering
This study investigates the synthesis, characterization, and optical properties of cobalt-doped β-tricalcium phosphate (Co-βTCP) nanoparticles prepared via microwave refluxing and sintered at 1000°C for 2 hours. Incorporating Co2+ ions into the βTCP structure significantly influences its microstructural and optical properties. X-ray diffraction analysis (XRD) reveals a contraction of the crystal lattice upon Co2+ doping, attributed to the substitution of larger Ca2+ ions (ionic radius 0.099 nm) with smaller Co2+ ions (ionic radius 0.074 nm). This reduces lattice parameters, cell volume, crystallinity, and smaller crystallite sizes. The degree of crystallinity decreases from 89.56% for pure β-TCP to 57.81% for 3Co-β-TCP. Scanning electron microscopy (SEM) shows that Co2+ doping produces more homogeneous powder with enhanced interconnectivity while maintaining a spheroidal agglomerated structure. The average particle size decreases from approximately 300 nm for pure βTCP to 246 nm for 3Co-βTCP. Fourier transform infrared spectroscopy confirms the successful integration of Co2+ ions into the βTCP lattice, evidenced by peak broadening and intensity reduction. Notably, incorporating Co2+ ions induces a striking colour change from white to pink, with intensity proportional to cobalt concentration. UV-Vis spectroscopy reveals characteristic absorption peaks at 530 and 678 nm, associated with Co2+ electronic transitions. The unique optical properties of Co2+ ions doped in βTCP open up new possibilities for its use in bioimaging and drug delivery systems.
Calcined Mullite Powder Produced from Waste Clay-Diatomite
Mullite powders have been fabricated using diatomite powder as Si and Al-nitrate as Al precursors, without using any additives. Samples were calcined at three temperatures (1300, 1400 and 1500 ºC) for a period of 1, 2 and 4 h. The obtained powders were analyzed using X-ray powder diffraction analysis (XRPD) PSA (Particle Size Analysis), FESEM (Field emission scanning electron microscopy) and EDXS (Energy-dispersive X-ray spectroscopy). Content of the crystalline phases with calcination temperature and dwell time was computed by X-ray powder diffraction analysis (XRPD), using POWDER CELL software. Field emission scanning electron microscopy (FESEM) images confirmed that the rod shape morphology of mullite particles, with the diameters around 500 nm, and lengths, 5 µm embedded in an amorphous matrix. XRPD of the sintered samples at 1300 ºC showed formation of thermally stabile phases (mullite, cristobalite and corundum) that makes the analyzed diatomaceous earth suitable for production of various types of construction and thermal insulating ceramic materials.
Cavitation Resistance of Laser-Sintered MS1 Steel
This study focuses on the determination of cavitation rate for samples produced by Direct Metal Laser Sintering (DMLS) of MS1 maraging steel powder without any post-processing thermal or mechanical treatment (as-built). The test samples, fabricated using an EOSINT M280 machine in a nitrogen atmosphere, were evaluated for their cavitation resistance using the ultrasonic vibration method as proposed by the ASTM G32 standard. Surface characterization to determine the duration of the experiment, as well as during and after the experiment to analyze changes in surface characteristics, was conducted using Scanning Electron Microscopy (SEM). Additionally, chemical analysis was performed using the Energy Dispersive X-ray Spectroscopy (EDS) method before and after the experiment to identify any changes and locations of significant surface damage. The mass loss of the samples over time was measured to calculate the cavitation rate. The goal of this research was to explore the potential applications of laser-sintered MS1 steel powder for manufacturing machine components and parts that are subject to cavitation erosion, due to the numerous benefits of additive manufacturing over traditional conventional technologies.
Capacitance Breakthroughs in Free-Standing Electrodes Through MXene Functionalization
The discovery of the large group of 2D materials called MXenes has gathered much attention due to their potential applications in various fields as well as the evergrowing discoveries about their nature. One of the most interesting applications is energy storage devices. Herein, we demonstrated the impact of the functionalization with two different silanes on the electrochemical and structural properties of Ti3C2Tx MXene. Materials are prepared and characterized as free-standing films obtained by a simple vacuum filtration method. The structure of the modified MXene electrodes was confirmed via SEM, FTIR, and XPS analysis. At the same time, the electrochemical properties were determined by cyclic voltammetry and galvanostatic charge-discharge in a two-electrode setup in aqueous electrolyte. Capacitance values at lower scanning speeds revealed the benefits of PEG silane functionalization (25.38 F/g), showing higher values compared to pure MXene (23.95 F/g) and MEMO silane (23.37 F/g). Capacitance retention decreased with the addition of silanes, but there was a significant increase in capacitance in the first 100 cycles. This study clarifies the benefits of adding different silanes to the structural and electrochemical properties of MXene for energy storage applications.
The B2O3/SiO2 Ratio and Dwelling time Dependent Crystallization Behavior, Phase Formation, Microstructural Features, and Thermal Behavior of SrO-CaO-Al2O3-ZnO-B2O3-SiO2-TiO2 Glass System
In the present study, the SrO-CaO-ZnO-Al2O3-B2O3-SiO2-TiO2 - based glass system is studied to investigate the effect of B2O3/SiO2 ratio and heat treatment dwell time on crystallization, phase development, and microstructural features in monolithic glass. The density of glasses increases with the increase in B2O3/SiO2 ratio as B2O3 has a higher molar mass than SiO2. The XRD patterns revealed that an increase in B2O3/SiO2 ratio facilitates the crystallization as evident in the case of glass of largest B2O3/SiO2 ratio (≈ 0.4) at 10 h dwelling at 850°C. However, at higher dwell time i.e. 20 and 30h, all glass specimens transformed to glass-ceramic, indicating a vital role of heat treatment time on crystallization. Scanning electron microscopic examination revealed that with the increase in the B2O3/SiO2 ratio, the anisotropic growth of crystals increases which is prominent for the glass having B2O3/SiO2 ratio (≈ 0.4). In addition, the corresponding temperature for various thermal events like sintering, softening, half-sphere, and melting is evaluated as a function of temperature at varying heating rates with the help of a heating stage microscope. The increase in heating rate, enhance the temperature for sintering, softening, and melting due the delayed arrival of required thermal energy as recorded in the heating stage microscope system.
Influence of rGO Concentration on the Strain and Conductivity in MAIPbCl2 Thin Films
The composite of methylammonium lead chloride iodide-reduced graphene oxide (MAIPbCl2/rGO) was prepared via the soak deposition method. In this work, the composite was studied with differences of weight percent (wt%) rGO on MAIPbCl2 precursor, whose rGO contents of 7 wt%, 8 wt%, 9 wt%, and 10 wt% were considered. A variety of the composition of all samples was observed and analyzed for optical, physical, and electrical properties using Fourier Transform Infrared (FTIR), UV-Vis Spectroscopy, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and the Hall effect. Normally, the mean crystallite size of MAIPbCl2 is 22.01 nm, whereas the composited MAIPbCl2/rGO obtained a maximum crystallite size of 29.88 nm (in the case of 8 wt% rGO). Remarkably, a MAIPbCl2/8 wt% rGO thin film assembly was produced that demonstrated the lowest strain of 7.07×10-2. Moreover, the activation energy determined from the nature logarithm of conductivity and 1000/T by using the temperature-dependent electrical transport data was displayed in a temperature range of 298–323 K. It was found that MAIPbCl2/8 wt%rGO improves the activation energy of 0.95 eV and yields the enhancement a maximum conductivity of 36.93 S/cm at 303 K.
Intergranular Capacitance of Sintered BaFe12O19 Doped with TiO2 in the very Low Frequency Region
A powder of BaFe12O19 composition (barium hexaferrite) was prepared by using the respective mixture of metal oxides and performing a solid-state reaction at 1000 °C/4h in air. The obtained barium hexaferrite powder was milled for a prolonged time in the planetary ball mill and agate mill to achieve submicron powder. The BaFe12O19 submicron powder was mixed with TiO2 nanopowder as a dopant. The prepared powder mixture was characterized by using XRD and SEM techniques. After that, the barium hexaferrite powder mixture was pressed into thin and small diameter size disk-shaped samples and sintered at different sintering profiles from 1050 °C to 1275°C/2h to 6h. The sintered samples were also characterized by using XRD and SEM. The main electrical properties such as capacitance (intergranular) and bulk resistance R at 1 Hz to 100 Hz were measured at room temperature. The dielectric permittivity was calculated from the equivalent scheme of disk capacitor. The obtained results were used for observing space charge relaxation effects and development of multilayer capacitor forenergy storage device.
Investigation of the Mechanical Properties of Concrete Incorporating Recycled Rubber Particles
Quantity of waste rubber generated by automobile tires is growing, posing an environmental threat. Rubber tire recycling was studied for usage in asphalt and waterproofing systems during past few decades. Globally, concrete is the most widely used building material. About 7% of CO2 emissions come from the cement production. The purpose of this research is to assess if using waste rubber and Portland cement together in composite material for structural applications is feasible. Waste tires (shredded to 0/1 mm) were used as fine aggregate replacement (in 2.5 and 7.5 %), together with PC and natural stone. An investigation of properties in fresh (slump test, bulk density, air content) and hardened state (bulk density, compressive strength) was performed on the rubberized concrete. The compressive strength decreased by increasing the rubber content for all w/c ratios (0.55-0.4). The addition of fine-sized rubber did not cause a retardation in cement hydration mechanism. According to the obtained compressive strengths, all designed rubberized concretes belong to a group of structural concretes.
Characterization and Densification of Hot Pressed ZrCN–ZrO2 Ceramics
ZrCN-ZrO2 ceramics were produced by hot pressing at a temperature of 2273 K, a pressure of 30 MPa, and a holding time at a given temperature of 15 minutes. Sintering was carried out in a vacuum environment. High-density ZrCN-ZrO2 ceramics were manufactured using zirconium nitride and carbide powders. Zirconium dioxide acted as a sintering additive due to its lowest melting point among the studied compounds. Using scanning electron microscopy and X-ray phase analysis, the presence of zirconium carbonitride as a matrix phase with different stoichiometry, depending on the change in the initial composition of the powders, was established. An increase in strength, hardness, Young's modulus, and crack resistance of the studied materials was observed with an increase in the content of zirconium nitride in the mixture of initial powders and a decrease in the porosity of the material. At the same time, a decrease in subgrains was recorded according to the results of X-ray phase analysis.
Investigation of Microstructural and Tribological Properties of a Commercial Brake Pad
In this study, micro and macro characterization of commercial brake pad by SEM, EDX, XRD and FTIR tests and determination of braking performance according to SAE J661 Test Procedure were aimed. The microstructure and spectrographic properties of the pad were compared with wear, density, surface roughness and hardness tests. In the study, it was determined that fibers, iron powders, oxides, vermiculite, graphite, barite and resin were homogeneously distributed in the microstructure and confirmed by the presence of :29 elements by EDX analysis. X-ray diffraction analysis revealed different morphologies and crystal forms in the test sample. The interaction of organic and inorganic compounds and functional groups of different elements were studied by FTIR analysis. In braking tests, the highest hot and cold coefficients of friction were 0.48 and 0.58, respectively, and the pad quality was determined as class G.
Influence of Grinding, Pressing and Sintering of the Powder 50.0 wt% Fe, 47.0 wt% BaTiO3 and 3.0 wt% TiO2 on Morphology, Microstructure, Magnetic and Electric Properties
A mixture of 50.0 wt% Fe, 47.0 wt% BaTiO3, and 3.0 wt% TiO2 powders is milled and then pressed and sintered. Samples sintered from ground powders have a structure consisting of plates. They consist of the crystalline phase BaFe12O19 and crystalline and amorphous phases Fe, BaTiO3, and TiO2. Samples sintered from powders ground for more than 180 min are compact and composed of BaFe12O19 crystals embedded in an amorphous matrix consisting of amorphous BaTiO3 and TiO2 phases. Magnetization of a sample ground for 220 min gradually decreases with increasing temperature up to 440 °C. This decrease results from the transition of ordered domains into chaotically directed domains. Above 440 °C, the thermal energy is sufficiently large to destroy ordered paramagnetic ferromagnetic and weakly ferromagnetic domains. During sample cooling in the absence of an external magnetic field, the temperature dependence of magnetization is the same as that obtained during heating in the magnetic field. However, during the sample cooling in the magnetic field, substantially higher values of magnetization are obtained. Considerably higher magnetization of the cooled sample remains even after switching off the external magnetic field. The sintered sample, previously pressed in the magnetic field, has a higher dielectric constant than the sample pressed in the absence of the magnetic field. The dielectric constant decreases with increasing frequency.
Effects of Rice Husk Ash Particles on Tribological Properties of Bronze Matrix Composite Brake Pads
The objective of this study was to examine and compare the physical, mechanical,and tribological properties of hybrid bronze metal matrix composite brake pads reinforced with fly ash and rice husk ash (RHA). To this end, metal matrix brake pad samples with various ratios of rice husk were prepared by hot pressing method. Density, hardness, friction coefficient, friction stability, and specific wear rate values were ascertained for the produced samples. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were employed to analyses the microstructure and wear surface. Results indicated that with the increase in rice husk ratio, the hardness value increased, whereas the density decreased. Furthermore, an augmentation in the friction coefficient values was attained by increasing the ratio of rice husk. The highest friction coefficient among all the samples produced was determined in the RHA-8 sample, with a value of 0.462. However, the lowest specific wear value was obtained in the RHA-6 sample, with 4.33 x 10-6 cm3/Nm. The coefficient of friction values obtained from all the samples produced were measured to be in the range of 0.3-0.6, which is the desired range for use as a brake pad material in automotive applications. This study demonstrated that RHA, an agricultural byproduct, may be utilized effectively in brake pads, thereby reducing production costs and enhancing the performance of the pads.
Investigation of the Effects of Surface Oxide Layer on Wear and Corrosion in NiTi Alloys: A Mechanical and Chemical Perspective
Nickel-Titanium (NiTi) alloys are widely applied in biomedical and industrial domains, mainly because of their unique superelastic characteristics and biocompatibility. However, their performance is often constrained by their tendency to wear and corrode, particularly under repetitive mechanical loading, harsh environmental conditions, and high friction coefficients. This study aims to reduce the wear rate and friction coefficient of NiTi alloys by forming oxide layers on the surface through heat treatment, while also increasing their corrosion resistance. It also examines the effects of high-temperature and prolonged heat treatments on surface performance. NiTi alloys were subjected to heat treatments at 900, 1000, and 1100 °C for 2 and 4 hours. Wear tests were conducted using the ball-on-disc method under three different loads (5N, 10N, and 15N), three different test durations (30, 60 and 90 min), and at a constant speed of 0.05 m/s, to measure the friction coefficient and wear rates. Additionally, the alloys mechanical and corrosion performance was evaluated through microhardness and electrochemical corrosion tests. The results showed that samples treated at 1100 °C for 4 hours exhibited a 146% increase in microhardness, reaching 640 HV, with the oxide layer thickness increasing to 462 μm. This oxide layer reduced the wear rate by 60%, bringing it down to 150x10-6 mm³/Nm during a 30 min test under a 15N load, while the friction coefficient decreased by 58%, dropping to 0.30 μ. In contrast, nonheattreated samples exhibited lower hardness (260 HV), higher friction coefficients (0.72 μ), and greater wear rates (370x10-6 mm³/Nm) under a 5N load over a 90 min test. Corrosion analyses indicated that samples treated at higher temperatures showed more positive corrosion potentials and significantly improved corrosion resistance, with the best performance observed in samples treated at 1100 °C for 4 hours. These findings suggest that the thick oxide layers formed during high-temperature, long-duration heat treatments significantly improve the wear resistance, reduce the friction coefficient, and enhance the corrosion resistance of NiTi alloys, making them more durable for industrial and biomedical applications.
Determining Threaded Machine Element Fabrication Technology by Pulsed Thermography
Non-destructive testing methods, including pulsed infrared thermography, have become quite common in materials evaluation. The method is suitable for checking the quality of the surface treatment of the material structure up to a certain depth and is increasingly applied in the areas of system maintenance and condition assessment of machine elements. Thus, when installing spare parts (screws) for military purposes, for example in airplanes, helicopters, tanks, or armored vehicles, as well as for commercial purposes, for example, excavators or other machines, it is necessary to inspect these parts additionally to be sure of their quality. The paper discusses the applicability of pulse infrared thermography in the quality control of screws, through the determination of the technology of making standard threaded joints (by rolling or cutting), as well as the technology of the final surface treatment of screws with a cadmium layer.
Influence of Iron on the Mullite Formation-Supplementary
Influence of iron on the crystallization mechanism of mullite obtained from the hybrid gels and doped with different concentrations of iron was examined. DTA analysis showed that iron addition had a beneficial effect on the mullite formation leading to the temperature decreasing as the amount of iron increased. X-ray diffraction and Mössbauer spectroscopy confirmed the increased iron content in the mullite lattice, which led to an increase in the unit parameter and was related to the higher iron content in regular octahedra, disordered octahedra, and tetrahedra with oxygen vacancies. Plate-like morphology observed by SEM suggests the two-dimensional crystal growth (n = 2). The most prominent kinetic models were used to estimate n and Ea from the DTA curves. Ea values increases as iron content increase, indicating that mullitization slows down due to iron incorporation. The Ea values for the undoped mullite sample ranged from 820 to 860 kJ/mol, from 820 to 890 kJ/mol for the irondoped mullite sample containing 6.0 wt% of Fe2O3, and from 960 to 1060 kJ/mol for the irondoped mullite sample containing 12 wt% of Fe2O3.
Effects of Soda Lime Glass Waste on the Physical, Mechanical and Aesthetics Properties of Sanitary-Ware Glazes
Recycling some waste industrial products in the traditional ceramics is a sustainable and environmentally friendly approach. This work focused on the incorporation of soda lime glass waste (SLGW) in the manufacturing of sanitary ware glazes. Eleven formulations were made under industrial conditions and compared to a reference industrial glaze. The findings revealed that the use of SLGW instead of dolomite (7 wt.%) leads to a significant improvement of the whiteness from 87.0 to 93.26 %. While the use of 20 wt. % SLGW instead of feldspar and 17 wt.% in place of the mixture (10 wt.% feldspar - 7 wt.% dolomite) results in an increased whiteness of 88.58 % and 89.42 %, respectively. The structural and morphological characterizations of the obtained glazes were identified by XRD, Raman spectroscopy and SEM analysis. However, the thermal analyses of the glazes were determined by DTA and TG techniques. Rheological behavior of the slip glazes; both physical and mechanical properties of the fired glazes have been also measured. This study revealed that soda lime glass wastes are good alternative materials, and the corresponding formulations were shown to be viable in the industry of the ceramic glazes. The most remarkable conclusion from this study was that the addition of SLGW improved the aesthetic aspect (whiteness and brightness) of sanitary ceramic glazes.
Red Mud-Fly Ash-Based Geopolymers as an Eco-Friendly Material for Immobilization of Toxic Pollutants (Pb and Cu) from Wastewater
The use of waste materials as a precursor for synthesizing geopolymer materials is increasingly being utilized. This research aimed to examine the potential use of red mud-fly ash geopolymers to remove toxic pollutants such as copper and lead ions from wastewater. Samples of different ratios of red mud (RM) and fly ash (FA) were synthesized through alkaline activation. Based on compressive strength a geopolymer (RMFAGP1) with the highest value of 29.54 MPa, was chosen for further research. The physical-chemical characterization of RMFAGP1 in terms of mineral composition and structure was performed using XRD, DRIFT and SEM analysis. BET analysis was used to define porosity, as well as the specific surfaces necessary for efficient adsorption. The batch equilibration method was used to determine the PZC value, which serves as a guide for predicting the adsorption process. The best adsorption efficiency was achieved at pH =4 (88.5%) i.e. at pH=5 (99.4%) for Cu and Pb, respectively. The performed analyses indicate that waste materials, such as red mud and fly ash, can be used as raw materials for obtaining a geopolymer that can effectively immobilize Pb and Cu from wastewater, offering a low-cost and eco-friendly solution.
Room Temperature Mössbauer Characterization of Ferrite with Spinel Structure
Cobalt ferrite (CoFe2O4) nanoparticle were obtained by different synthesis methods: coprecipitation (CO), ultrasonically assisted coprecipitation (US-CO), coprecipitation followed by mechanochemical treatment (MC-CO), microemulsion (ME) and microwave assisted hydrothermal synthesis (MW-HT). The structure and cation distribution are investigated by XRD diffraction analysis and Raman spectroscopy. The parameters such as chemical shift, quadruple splitting and hyperfine field and site occupancy of Fe3+ were determined by Mössbauer spectroscopy. The 57Fe-Mössbauer spectrа of the CoFe2O4 wеrе measured at room temperature in ± 12 mm s-1 Doppler velocity range. The 57Fe-Mössbauerspectrа of the CoFe2O4 samples wеrе fitted with the extended Voigt-based fitting method.
Thermal Stability and Leaching Behavior of Alkali-Activated Slag Doped with Electric Arc Furnace Dust
The study presented in this paper explores the simultaneous valorization of electric arc furnace slag (EAFS) and electric arc furnace dust (EAFD) through an alkali activation process, as well as the thermal stability of the resulting product. Moreover, environmental fingerprints of alkali activated slag doped with EAFD, before and after thermal treatment, were evaluated. The results demonstrated the feasible alkali activation of EAFS in the presence of EAFD yielding a product that met the criteria which enables its application in a civil engineering at ambient and at elevated temperatures (1000 ºC). Moreover, the EN12457-2 leaching test results, demonstrated that unheated alkali-activated slag with addition of 5% EAFD met the criteria for disposal at non-hazardous landfills as per European Directive 2003/33/CE. However, environmental fingerprints of alkali activated slag with 5% EAFD after heating to 1000 °C, is of concern since chromium release exceeded the permissible concentration requiring disposal in hazardous waste landfills.