Glassy rods of the multicomponent ferromagnetic $ \mathrm{Fe_{65.5}Cr_4Mo_4Ga_4P_{12}C_5B_{5.5}} $ 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).
Cadmium ferrite nanoparticles ($ \mathrm{CdFe_2O_4} $ NPs) have been synthesized by impregnation method followed by heat treatment. Investigation the structural and morphogical properties of CdFe2O4 NPs was done using XRD, FTIR and TEM techniques. On the other hand, $ \mathrm{CdFe_2O_4} $ NPs' magnetic characteristics were investigated. The success of the preparation technique utilized to produce pure nanocrystalline pure $ \mathrm{CdFe_2O_4} $ with a size of 26 nm was validated by XRD findings. According to FTIR based functional groups, the resulting cadmium ferrite has random spinel structure. The morphological characteristics of the synthesized ferrite, as determined by TEM technique, highlight the production of spherical-like particles at the nanoscale. Additionally, the prepared ferrite displays low magnetization and coercivety with paramagnetic behavior. The current work provides new opportunities for the simple, cost-effective, and efficient synthesis of nanomaterials for usage in useful application such as gas sensing and photo catalysis.
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 ($ \mathrm{Cu_x}S $) 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 $ \mathrm{Cu_x}S $ 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.
In this work, erbium oxide (Er₂O₃), a rare-earth oxide, was employed as a dopant in barium titanate (BaTiO₃) ceramics. The BaTiO₃-based materials were prepared using a conventional solid-state reaction technique. Dopant levels ranging from 0.01 to 1.0 wt.% were incorporated into the ceramic matrix. The prepared samples were sintered at 1380°C for a duration of four hours. The structural, morphological, and optical characteristics of the resulting ceramics were examined using multiple methods, including X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and photoluminescence (PL) analysis. For samples with a low Er₂O₃ concentration (0.01 wt.%), grain sizes were found to range between 10 μm and 30 μm. In contrast, increasing the dopant content to 1.0 wt.% inhibited abnormal grain growth, leading to a more refined microstructure with grain sizes in the range of 2 μm to 10 μm. Dielectric properties, including permittivity and loss, were measured as functions of both frequency and temperature in order to establish a relationship between microstructural evolution and dielectric behavior. The amphoteric nature of rare-earth ions was found to enhance dielectric permittivity while reducing dielectric losses compared to undoped BaTiO₃. Furthermore, the effect of dopant concentration on the temperature dependence of the dielectric constant was also evaluated.
The present work investigates the effects of sintering temperatures and different sintering atmospheres on M2 high-speed steel. It is well known from the pseudo-binary phase diagram that, with an increase in temperature from 1250 ºC to 1350ºC, the sintering process changes from solid-state sintering to super-solidus liquid-phase sintering, resulting in increased densification with increasing sintering temperature owing to enhanced sintering kinetics and liquid formation. The carbide particle size also increases with increasing sintering temperature, resulting in coarser carbide and the formation of a carbide network at higher temperatures. It has been observed that densification increases in H2 atmosphere to ~99% compared to N2 (81%) and Ar (93%). Furthermore, carbide forms more finely in an N2 atmosphere, but it has a higher pore density. In the H2 atmosphere, coarse carbides are uniformly distributed in the alloy; moreover, a coarse carbide network is detected in the Ar atmosphere. Furthermore, increasing the sintering temperature from 1250ºC to 1350ºC results in a rise in bulk hardness from 119 HV0.2 to 239 HV0.2. However, Bulk hardness is also improved in the H2 atmosphere to 453 HV0.2 sintered at 1300ºC.
Potential industrial applications of bentonite from a regional deposit were investigated. The material was investigated beyond state-of-the-art to optimize its quality for use in ceramic sector. Representative bentonite samples (B1, B2, B3) were analyzed. The grain size was determined by wet sieving and laser diffraction analysis. Clay fractions were analyzed using XRD. Chemical composition was assessed by AAS technique. Structural features, inclusions, and microcracks were monitored by scanning electron microscopy. Physicochemical parameters included swelling index, total cation exchange capacity, exchangeable cations type, refractoriness, water adsorption capacity, and plasticity index. The types of chemical bonds were determined by FTIR. DSC/TGA was employed in the thermal behavior analysis. The investigation revealed that samples are non-swelling Ca-type bentonites. XRD analysis indicated presence of major mineral montmorillonite, accompanied by cristobalite, feldspar, and calcite. The examined bentonites display high plasticity, adequate swelling/water absorption, viscosity, and thixotropy, making them well-suited for ceramic industry applications.
This study investigates the effects of milling time and sintering temperature on the properties of Nb-Cu, prepared by high-energy milling and spark plasma sintering (SPS). Xray Diffraction (XRD), laser scanning confocal microscopy and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) were used to characterize microstructural changes and discuss their influence on the relative density, microhardness, and electrical conductivity of the composite. The samples with higher milling time and temperature had higher values of density. Conductivity reached a maximum value of 1.78 x $ 10^{-7} $ $ (mΩ)^{-1} $. The hardness reached was 473.84 HV. Superconductivity analysis revealed a twostage transition in resistance for Nb-Cu, with drops at 11.2 K and 6.6 K, indicating Cu-Nb interaction effects. This behavior contrasts with the single transition observed in pure Nb. Principal Component Analysis (PCA) confirmed a strong positive correlation between microhardness, relative density, and electrical conductivity, indicating that these properties are primarily influenced by sintering temperature.
The tribological behaviors of direct metal laser sintered materials should be further studied, as it is important to know their wear properties before use. In this research, the tribological properties of Ti6Al4V samples produced by conventional (rolling) and additive manufacturing methods using different production parameters were compared. The results revealed that production parameters strongly influence the hardness and wear resistance of additive manufacturing parts. Among the selected test parameters, keeping the energy density between 40–50 J/$ mm^{3} $ to produce a Ti6Al4V sample ensures that the hardness values are at the same level as those of the rolled one.
Mg-Zn-Ca alloy, a material widely recognized for its potential as a biomaterial, has been the focus of our research. In this work, powder metallurgy was used to create three alloys with mass fractions: 89Mg–10Zn-1Ca, 93Mg–6Zn-1Ca, and 97Mg–2Zn-1Ca wt.%. Powders were mixed in the mentioned parts where magnesium served as the substrate. The compaction pressure applied to the sample was 200 MPa. The sintering process was then conducted at two temperature levels, 500 and 600°C, in an argon gas environment. Hardness and microstructural observations were conducted on the samples. Electrochemical corrosion tests were performed using a potentiometer. Additionally, the potential of hydrogen (pH) value in simulated body fluid was evaluated. The results indicated that the alloy with the highest zinc content of 10% at a sintering temperature of 600°C exhibited the best potential as an implant material, showing the highest hardness test results and the lowest corrosion rate.
This paper presents a laboratory study on the physical properties of mortar incorporating expanded vermiculite. The basic cement-lime mortar matrix remained unchanged, while the proportions of vermiculite were varied at 10%, 20%, and 30%. The research results demonstrated a significant improvement in physical properties, including compressive and flexural strength, as well as the static modulus of elasticity. This study establishes relationships between these properties and examines the impact of expanded vermiculite on characteristics such as air void content, capillary suction of hardened mortar, total porosity (according to SIA 262, Appendix A), gas and air permeability, and capillary water absorption. Additionally, the water permeability of the mortar was tested, along with its internal resistance to freeze-thaw cycles, up to 200 cycles. The findings of this laboratory research contribute to filling an existing scientific gap, demonstrating that the physical properties of mortar with the addition of expanded vermiculite at 10%, 20%, and 30% are significantly improved compared to mortar without vermiculite.
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 $ Co^{2+} $ 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 $ Co^{2+} $ doping, attributed to the substitution of larger $ Ca^{2+} $ ions (ionic radius 0.099 nm) with smaller $ Co^{2+} $ 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 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 $ Co^{2+} $ ions into the βTCP lattice, evidenced by peak broadening and intensity reduction. Notably, incorporating $ Co^{2+} $ 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 $ Co^{2+} $ electronic transitions. The unique optical properties of $ Co^{2+} $ ions doped in βTCP open up new possibilities for its use in bioimaging and drug delivery systems
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 MP$ a.m^{1/2} $, and σ: 421±9.2 MPa values. These data presented herein pave the way for producing tailorable structure-property relationships in various ZrO2 ceramic applications, e.g., dental and cutting tools.
Ceramic Matrix Composites (CMCs) are transformational materials with outstanding thermal stability, mechanical strength, and resilience to severe conditions, making them important in aerospace, energy, and defence applications. This paper examines the novel approaches and problems of creating CMCs for ultra-high-temperature settings, emphasizing material selection, reinforcing strategies, and advanced production techniques. Recent improvements include using silicon carbide (SiC) and zirconium oxide ($ \mathrm{ZrO_2} $) 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 highdemand 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.
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.
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 450?C 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 ?m 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.
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.
In the paper, the cavitation resistance of cordierite samples with the addition of 10%, 15% and 20% talc, sintered at 1200?C, was investigated. The ultrasonic vibration method with a stationary sample according to the ASTM G32 standard was applied. The formation and development of damage to the surface of the samples was monitored using a scanning electron microscope and the level of damage to the surface of the samples was quantified using image analysis. The change in the mass of the samples as a function of the cavitation time was monitored to determine the cavitation rate. By measuring the mass loss and morphological analysis of the pits formed on the surface of the sintered samples of the cordierite-talc ceramics, the mechanism of degradation and resistance to the effect of cavitation was monitored. The obtained results were compared with the results of earlier tests of cavitation resistance of sintered cordierite samples. The addition of talc in the mixture with cordierite significantly improved cavitation resistance of the sintered material compared to sintered pure cordierite. The tests were done to see the potential application of this material in hydrodynamic conditions, especially because of the strong corrosion resistance of these refractory materials.
Europium-doped fluorapatite $\mathrm{Ca}_{10-x}(\mathrm{PO}_{4})_{6}\mathrm{F}_{2}:x\mathrm{Eu}^{3+}$ (x = 0.05, 0.1 and 0.5) nanoparticles were successfully synthesised by a coprecipitation method at room temperature and calcination at 700 ⁰C. Characterisation of samples using XRD, TEM, TGA-DTA, FTIR and photoluminescence spectroscopy showed that the obtained calcium deficient fluorapatite nanoparticles exhibit a high degree of crystalline disorder, i.e. Eu doping leads to a remarkable structural amorphisation of fluorapatite. The crystallinity and crystallite size of the obtained samples decreased with the increase of Eu doping. The lattice parameters of the calcined samples decrease noticeably with the increase in $ Eu^{3+} $ dopant concentration. When excited by UV radiation at 393 nm, all europium-doped fluorapatite samples showed the characteristic $^{5}D_{0}–^{7}F_{0–4}$ emission lines of $ Eu^{3+} $ions. According to the luminescence results, the $ Eu^{3+} $ ions have largely replaced the $ Ca^{2+} $ ions in the Ca(I) position in the crystal lattice of the fluorapatite.
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.
In this study, porous ceramics, based on available and cost-effective raw materials natural zeolite and kaolin clay, were synthesized and examined as an adsorbent for removing ammonium (NH4+) ions from aqueous solutions. The synthesis was carried out using the foaming method with the addition of sodium dodecyl sulfate as the foaming agent, polyvinyl alcohol as an organic binder, and hydrogen peroxide as the blowing agent. The obtained green and sintered samples were characterized by thermogravimetric analysis, scanning electron microscopy, X-Ray diffraction, and Fourier transform infrared spectroscopy. After sintering, the porosity was 79.49%. The NH4+ adsorption kinetics and isotherms fit the pseudo-second-order and Langmuir models, confirming chemisorption. The maximum adsorption capacity obtained using the Langmuir model was approximately 7.66 mg g-1. The thermodynamic parameters showed that adsorption is a spontaneous and exothermic process. Based on the obtained results, it was demonstrated that the synthesis of porous ceramics based on natural zeolite and kaolin clay is a practical way to increase the adsorption performance of natural zeolite for NH4+ removal from water solutions.
