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Epoxyamine matrix-based composites containing 15 wt% of Fe nanoparticles and 1.5 or 2 wt% of carbon nanotubes, as well as composites containing only Fe particles, have been studied using microwave methods and various scanning probe microscopy techniques, such as scanning capacitance microscopy and scanning Kelvin probe force microscopy. The composites were prepared using technological methods that improve their homogeneity. Probe current dependences investigated by applying different voltages to the probe in the Kelvin probe force microscopy mode have shown that the falling regions of the dependences at both positive and negative values of the bias voltage are found only for the sample containing both the Fe particles and the CNT in the "soft epoxy" matrix. Microwave measurements of the transmission and reflection coefficients were performed in the frequency range from 26 to 38 GHz. The field dependences of the microwave power dissipation have been plotted. The ferromagnetic resonance in the composites has been investigated. Frequency dependences of the complex dielectric permittivity of the composites have been determined. Microwave properties of the CNT-containing and CNT-free composites have been compared. [ABSTRACT FROM AUTHOR]

Iron (Fe) is regarded as a candidate material for biodegradable metallic implants due to its biocompatibility and ability to degrade in physiological environemnt. However, the degradation rate in the physiological environment is too slow for clinical applications. It is necessary to accelerate the rate such that the degradation is compatible with tissue growth. Furthermore, the implant material needs to be bioactive for promoting osteointegration, osteoconductivity, cell proliferation and biological apatite formation. Nano-sized bioactive hydroxyapatite (nHA) was incorporated into a porous Fe matrix to enhance the bioactivity and degradation rate. Electrochemical studies in biomemtic NaCl solution, revealed that incorporation of nHA in porous Fe can increase the degradation by 2.5 times compared to the pure iron counterparts with similar porosity. Furthermore, immersion tests in simulated body fluid (SBF) revealed that nHA added samples displayed enhanced biomineralization and degraded at a rate three times faster than pure iron in this environment. The incorporation of nHA into the iron matrix aided in the formation of biomineralized hydroxyapatite. The composite surface promoted the cell adhesion and proliferation and the L929 fibroblast cells exhibited good cell viability. It is proposed that porous morphology incorporated with nHA can improve biomineralization and tailor the degradation rate of Fe-based materials in physiological environment. [ABSTRACT FROM AUTHOR]

The necessity for high operational temperatures presents a considerable obstacle to the commercial viability of solid oxide fuel cells (SOFCs). The introduction of active co-dopant ions to polycrystalline solid structures can directly impact the physiochemical and electrical properties of the resulting composites including crystallite size, lattice parameters, ionic and electronic conductivity, sinterability, and mechanical strength. This study proposes cobalt–iron-substituted gadolinium-doped ceria (CoxFe1-xGDC) as an innovative, nickel-free anode composite for developing ceramic fuel cells. A new co-precipitation technique using ammonium tartrate as the precipitant in a multi-cationic solution with Co2+, Gd3+, Fe3+, and Ce3+ ions was utilized. The physicochemical and morphological characteristics of the synthesized samples were systematically analysed using a comprehensive set of techniques, including DSC/TGA for a thermal analysis, XRD for a crystallographic analysis, SEM/EDX for a morphological and elemental analysis, FT-IR for a chemical bonding analysis, and Raman spectroscopy for a vibrational analysis. The morphological analysis, SEM, showed the formation of nanoparticles (≤15 nm), which corresponded well with the crystal size determined by the XRD analysis, which was within the range of ≤10 nm. The fabrication of single SOFC bilayers occurred within an electrolyte-supported structure, with the use of the GDC as the electrolyte layer and the CoO–Fe2O3/GDC composite as the anode. SEM imaging and the EIS analysis were utilized to examine the fabricated symmetrical cells. [ABSTRACT FROM AUTHOR]

Water pollution is calling for a sustainable remediation method such as the use of metallic iron (Fe0) to reduce and filter some pollutants, yet the reactivity and hydraulic conductivity of iron filters decline over time under field conditions. Here we review iron filters with focus on metallic corrosion in porous media, flaws in designing iron filters, next-generation filters and perspectives such as safe drinking water supply, iron for anaemia control and coping with a reactive material. We argue that assumptions sustaining the design of current Fe0 filters are not valid because proposed solutions address the issues of declining iron reactivity and hydraulic conductivity separately. Alternatively, a recent approach suggest that each individual Fe0 atom corroding within a filter contributes to both reactivity and permeability loss. This approach applies well to alternative iron materials such as bimetallics, composites, hybrid aggregates, e.g. Fe0/sand, and nano-Fe0. Characterizing the intrinsic reactivity of individual Fe0 materials is a prerequisite to designing sustainable filters. Indeed, Fe0 ratio, Fe0 type, Fe0 shape, initial porosity, e.g. pore size and pore size distribution, and nature and size of admixing aggregates, e.g. pumice, pyrite and sand, are interrelated parameters which all influence the generation and accumulation of iron corrosion products. Fe0 should be characterized in long-term experiments, e.g. 12 months or longer, for Fe dissolution, H2 generation and removal of contaminants in three media, i.e., tap water, spring water and saline water, to allow reactivity comparison and designing field-scale filters. [ABSTRACT FROM AUTHOR]

In this work, the tribological properties of a novel iron‐based self‐lubricating composite as the tribopairs of a plunger pump were systematically studied on an end‐face tribometer, and the tribological mechanism was also revealed. The results show that the wear mechanism of the composite can be ascribed to adhesive wear when the sliding speed is lower than 1.5 m/s. As the sliding speed increases from 1.5 to 2.0 m/s, the wear type transforms to oxidative wear due to the increase of tribo‐oxidation. In addition, the failure criteria of the tribopair composite materials are summarised. When the average coefficient of friction is greater than 0.04, or the wear rate is greater than 9.66 μm3/(N m), the tribopair fails. This offers a valuable reference for industrial application of the tribopairs made from the iron‐based self‐lubricating composite. [ABSTRACT FROM AUTHOR]

Yttria-stabilized zirconia (YSZ) oxide ceramic powder is a thermal-barrier material used to fabricate thermal barrier coatings (TBC). In this study, to improve the electromagnetic wave (EMW) absorbing properties of TBCs, microwave-absorbing samarium iron nitrogen (SmFeN) particles were used to prepare SmFeN/yttria-stabilized zirconia (YSZ) composites. To study the effect of the SmFeN/YSZ interfaces on the EMW-absorbing properties of the SmFeN/YSZ composite, SmFeN/YSZ interfaces were built in different ways in composite materials having the same mass ratio of 1:1, for example, SmFeN and YSZ particles homogeneously mixed together, SmFeN/YSZ interfaces perpendicular and parallel to the EMW incident direction, and different interfaces between YSZ and SmFeN. Thus, the microwave absorbing performance of the samples, including the electromagnetic parameters, attenuation coefficient, eddy-loss current (C 0), impedance matching, and minimum reflection loss (RL min) values were examined and analyzed. The results demonstrate that interfaces perpendicular to the direction of the EMWs can increase the contact area and enhance the interfacial absorption effect. Further, when the wave-absorbing agent was placed in the middle of the composite, its wave-absorbing effect was the best among all the samples, yielding RL min = −27.824 dB and effective absorption bandwidth (EAB) = 8.5453 GHz (effective absorption frequency range 7.9256–16.4709 GHz for a 7.2-mm-thick layer). Crucially, the frequency and bandwidth at which the best absorption occurred could be tuned by adjusting the thickness of the coating. This is because the interfaces in the samples resulted in polarization enhancement and anomalous dispersion, leading to large dielectric losses. Overall, the use of a coaxial measurement technique is highly efficient for EMW absorbing body design and process simulations. [ABSTRACT FROM AUTHOR]

The influence of the introduction of tungsten carbide nanocrystalline on the microstructure and mechanical characteristics of Ni-WC composite overlays on tool steel was studied. In addition to the improved fraction of retained WC phase and decreased fraction of brittle secondary carbide phases, the influence of the addition of tungsten carbide in nano-size on the microstructure, and mechanical behaviors of the deposited layer was considered. Tungsten carbide nanoparticle in the range 1-7 wt.% was added to existing commercial powder and deposition was carried out. The optimum welding parameters were determined. The results showed that the Ni-WC overlays possessed microstructures including γ-Ni dendrites, with interdendritic Ni-Fe-based eutectics, borides (Fe-Cr)2B, and carbides (Fe, Cr)7C3. With the introduction of WC-nanocrystalline, refining the microstructure was achieved and the dissolution of WC particles enhanced the generation and growth of secondary carbide phases. The strengthening contribution of the reinforcing particles in alloy with 3 wt.% causes an increase in hardness, while the hardness values decrease as the content of WC increases by 7 wt.%. [ABSTRACT FROM AUTHOR]

Biochar-zero-valent iron composites are promising materials for the removal of heavy metals from aqueous solution, but further research is still required on the co-removal of multiple heavy metals. This paper presents the performance, effects and mechanisms of peanut shell biochar (BC)-supported zero-valent iron (ZVI) composites in the co-removal of Cd(II) and Cr(VI) from aqueous solution. Samples were subjected to the isotherm test, the kinetic test, the adsorption performance test and microscopic tests, and impact factors such as initial pH, reaction time, dosage and BC/ZVI mass ratios were considered. The results show that the removal efficiency of biochar-zero-valent iron composites for Cd(II) and Cr(VI) co-removal is significantly higher compared to individual applications of zero-valent iron and biochar. Under the condition of dosage of 0.2 g, initial pH = 4.0, and BC/ZVI mass ratio of 4:1, the removal efficiency of Cd(II) and Cr(VI) can reach 98.66% and 98.45%, respectively. In this case, the maximum adsorption capacity of Cd(II) and Cr(VI) can reach 20.44 mg/g and 3.70 mg/g. The removal of Cd(II) follows the pseudo-second-order and Freundlich model, whereas the removal of Cr(VI) is better fitted by pseudo-first order and Langmuir model. The co-removal process of Cd(II) and Cr(VI) can be divided two phase, and the mechanisms of Cd(II) and Cr(VI) are also remarkably distinct. The reduction, adsorption, complexation or co-precipitation are the dominant mechanisms for Cr(VI) removal, while the complexation of biochar and adsorption of the iron oxyhydroxide layer predominate for Cd(II) removal. [ABSTRACT FROM AUTHOR]

The development of metal matrix composites is important for industrial applications that require lightweight materials with high strength, stiffness, and wear resistance. In this investigation, Al2024 alloy was reinforced with fly ash and silicon (SiC) carbide hybrid composites using the stir‐squeeze cast technique. Two sets of composites were fabricated: one with 3 wt% fly ash and 3 wt% SiC, and the other with 3 wt% fly ash, 5 wt% SiC, and 3 wt% fly ash, 7 wt% SiC The composites were prepared using 25 and 75 mm diameter dies. Microstructural characterization of the specimens was performed using scanning electron microscope, X‐ray powder diffraction, and energy dispersive X‐ray spectroscopy analysis. Mechanical properties, such as yield strength, ultimate tensile strength, and hardness, were determined according to American Society for Testing and Materials standards. The hybrid composites fabricated in the 25 mm diameter cast iron molds exhibited superior mechanical properties compared to those prepared in the 75 mm diameter molds. The addition of fly ash and SiC particulates enhanced the mechanical properties of the Al2024 alloy. These composites showed improved strength, toughness, and ductility. [ABSTRACT FROM AUTHOR]

The magnetic microwave absorption (MA) materials are prone to corrosion in high temperature and high humidity environments, leading to a deterioration in the MA performance, so, the development of composite coatings with comprehensive properties such as excellent absorption performance, corrosion resistance, and oxidation resistance holds significant importance in the field of stealth technology. In this study, a core-shell structure MA materials titanium dioxide coated carbonyl iron particle (CIP@TiO 2) was prepared and utilized as a filler in the preparation of composite coatings. The results show that the low-frequency impedance modulus of composite coating improves by three orders of magnitude from 4.5 × 105 Ω cm2 to 2.5 × 108 Ω cm2, demonstrating outstanding corrosion resistance. The TiO 2 shell not only improves CIP's electromagnetic parameters but also optimizes the impedance matching of the composite material. The CIP@TiO 2 coating achieves a minimum reflection loss of −56.8 dB at a thickness of 1.2 mm and an effective bandwidth of 6.57 GHz at a thickness of 0.6 mm, demonstrating excellent absorption performance. This study provides a novel approach for preparing composite materials with superior corrosion-resistant and absorptive properties. [ABSTRACT FROM AUTHOR]

Highlights Designing an electromagnetic wave absorber that can meet the needs of wide frequency, high efficiency, wide‐angle absorption and strong mechanical bearing capacity is still a challenge. In this paper, a core‐shell structure Carbonyl iron powder (CIP)@Carbon (C)@Carbon black (CB) composite material was prepared by coating and vacuum carbonization process. Using it as a filler, PLA as a matrix to prepare 3D printing composites. The unique structure and material distribution of CIP@C@CB gives the composite a variety of loss mechanisms that greatly improve microwave absorption capacity. Superstructure electromagnetic wave absorbers with integrating broadband microwave absorption and good mechanical bearing performance were designed and prepared by using CIP@C@CB/PLA 3D printing composites. By optimizing the parameters of this superstructure absorber, an EAB of 5.5–18 GHz is realized, and its yield limit reaches 11.5 MPa. In addition, the superstructure absorber also has excellent wide‐angle absorption capacity, with an effective absorption bandwidth (EAB) of 10GHz at 0°–40° transverse radio (TE) and 0–70° transverse magnetic wave (TM). This research offers a straightforward and effective method for crafting broadband wide‐angle absorbers that possess the added advantage of mechanical load‐bearing capacity. The core‐shell structure was prepared by coating and carbonization processes. The unique structure of CIP@C@CB enhances the interfacial polarization effect. At a thickness of 2 mm, 30% CIP@C@CB/PLA achieves a maximum EAB of 5.0 GHz. The stepped structure achieves 90% effective absorption in the 5.5–18 GHz range. [ABSTRACT FROM AUTHOR]

Most studies on soft magnetic composites (SMC) have focused on traditional compaction. However, this consolidation method leads to low densities and therefore, poor magnetic properties. For this reason, this work focuses on the study of an iron phosphate (Fe 3 (PO 4) 2) coating to develop SMCs consolidated through a novel field-assisted sintering technology (FAST) and compares it with traditional compaction. A direct relationship is demonstrated between the thickness of the coating obtained and the amount of reagent added to the synthesis as well as the inverse relationship between the thickness of the coating and the powder/acetone ratio. By contrast, thermal analysis shows that the desired phase Fe 3 (PO 4) 2 is stable up to 900 °C. Between 900 and 960 °C, iron phosphate decomposes into Fe–P and SiO 2. At higher temperatures, the decomposition process is completed, and the Fe–P phase reacts with Fe–3Si particles, resulting in an FeSiP matrix with a non-continuous layer of surrounding SiO 2. The highest compact density and static magnetic properties are obtained for the SMC prepared with 2 wt% H 3 PO 4 and a powder/acetone ratio of 2.5 g/mL consolidated by FAST, providing a density of 6.59 g/cm3, a magnetic saturation of 1.752 T and a coercivity of 313.4 A/m. In addition, this SMC results in the highest permeability in the entire audio-frequency range (40 up to 100 kHz) as well as high electrical resistivity (3.18·105 μΩ cm) and the lowest power losses up to 10–20 kHz (31.7 mW/cm3 at B = 50 mT and f = 10 kHz). However, cold-press consolidation leads to higher operating frequencies, reaching a permeability of 24 up to 1 MHz, and the lowest power losses for frequencies greater than 10–20 kHz (414 mW/cm3 at 100 kHz and B = 50 mT) due to the reduction of eddy currents obtained by the higher electrical resistivity and lower number of coating defects. [ABSTRACT FROM AUTHOR]

Intertrack fluctuation of microstructure and mechanical properties is one of the important characteristics for nonuniformity in laser cladding processes. The understanding of the fluctuation helps to improve the wear resistance of deposited materials. In this paper, the phase structure, element distribution, hardness variation and carbides were identified and compared between the cladding zone (CZ) and the heat-affected zone (HAZ) in T15 steel laser cladding. A calculation method was proposed to reveal the physics of the solidification and precipitation behavior of carbides by combining the finite element method (FEM) and thermodynamic calculations. The results showed that the hardness of the intertrack HAZ was higher than the hardness of the CZ due to the high amount and small size of vanadium carbide (VC) particles. The calculation proved that the major strengthening phase was VC precipitate, while tungsten carbide (WC) was not stable in the cooling process and converted to Fe3W3C. The volume fraction of VC in the HAZ was 14.3%, which was higher than the volume fraction in the CZ, which was only 10.0%. The high temperature was prone to a high volume fraction and many VC precipitates with a small radius in the intertrack HAZ, which qualitatively agreed with the experimental characterization. [ABSTRACT FROM AUTHOR]

Metal selenides are widely considered as an emerging anode electrode material for lithium‐ion batteries (LIBs). Hence, the present study uses a conductive carbon materials matrix such as carbon nanotubes (CNTs) with copper–iron selenide (CuFeSe2). The composites (CuFeSe2@CNTs) are synthesized by a hydrothermal method and examined for electrochemical performance as anode applications in LIBs. Herein, the CuFeSe2@CNTs show excellent specific capacity of 783.7 and 720.6 mA h g−1 at 0.1 and 1 A g−1, respectively. This composite further exhibits a high‐capacity value compared to only FeSe2 and CuFeSe2 and a reversible capacity of 691 mA h g−1 after 200 cycles at 1 A g−1 current density. Moreover, the homogeneous combination of CuFeSe2 nanoflakes and CNTs provides structural stability that reduces the volume change during lithium‐ion interactions and successively improves the conductivity of the complex, which is advantageous for better ion and electron kinetics during the reaction. [ABSTRACT FROM AUTHOR]

A facile preparation protocol for a porous carbon skeleton supported lithium iron phosphate nanocomposite material (LFP/C) is derived from a ferric gallate (Fe-GA) metal–organic framework (MOF) precursor. [Display omitted] Lithium iron phosphate (LiFePO 4 , LFP) has become one of the most widely used cathode materials for lithium-ion batteries. The inferior lithium-ion diffusion rate of LFP crystals always incurs poor rate capability and unsatisfactory low-temperature performances. To meet with the requirements from the ever-growing market, it is of great significance to synthesize carbon supported LFP nanocomposite (LFP/C) cathode materials using cost effective and environmentally friendly methods. In this work, an LFP/C cathode material is straightforwardly prepared from a metal–organic framework (MOF) precursor ferric gallate (Fe-GA) using its self-template effect. The Fe-GA precursor is firstly fabricated from the redox coprecipitation reaction between Fe foils and gallic acid (GA) molecules in mild aqueous phase. Then the Fe-GA is directly converted to the LFP/C sample after a following solid-state reaction. In half-cells, the LFP/C composite exhibits a reversible capacity of 109.7 mAh·g−1 after 500 cycles under the current rate of 100 mA·g−1 at 25 °C as well as good rate capabilities. In the LFP/C//graphite full-cells, the LFP/C composite can deliver a reversible capacity of 71.4 mAh·g−1 after 50 cycles in the same condition as the half-cells. The electrochemical performances of the LFP/C cathode in half-cells at lower temperature of −10 °C are also examined. Particularly, the evolution of samples has been explored and the lithium-ion storage mechanism of the LFP/C cathode has been unveiled. The sample synthesis protocol is straightforward, eco-friendly and atomic efficient, which can be considered to have good potential for scaling-up. [ABSTRACT FROM AUTHOR]

Cancer is a major worldwide public health problem. Although there have already been astonishing advances in cancer diagnosis and treatment, the scientific community continues to make huge efforts to develop new methods to treat cancer. The main objective of this work is to prepare, using a green sol–gel method with coconut water powder (CWP), a new nanocomposite with a mixture of Gd3Fe5O12 and ZnFe2O4, which has never been synthesized previously. Therefore, we carried out a structural (DTA-TG and X-ray diffraction), morphological (SEM), and magnetic (VSM and hyperthermia) characterization of the prepared samples. The prepared nanocomposite denoted a saturation magnetization of 11.56 emu/g at room temperature with a ferromagnetic behavior and with a specific absorption rate (SAR) value of 0.5 ± 0.2 (W/g). Regarding cytotoxicity, for concentrations < 10 mg/mL, it does not appear to be toxic. Although the obtained results were interesting, the high particle size was identified as a problem for the use of this nanocomposite. [ABSTRACT FROM AUTHOR]

This paper describes the improvements in microwave absorbency and other functional properties of silicone rubber-based nanocomposite sheets with iron (Fe)- and nickel (Ni)-deposited nanographite (NG). NG was synthesized using the ball milling method and then acid functionalized. The deposition was performed on acid-functionalized NG dispersed in an electrochemical bath containing Fe and Ni salts in a designed fluidized bed reactor system. The electrolyte concentration, stirring speed, applied current, and time of electrolysis were optimized. X-ray diffraction, Fourier transform infrared spectroscopy, Brenner–Emmet–Teller analysis, transmission electron microscopy, scanning electron microscopy, and atomic force microscopy were used to characterize the structural as well as morphological properties of the material. The applied current, average particle size, and density of the electrolyte–powder suspension have a significant impact on the material's morphology and microwave absorption capabilities. To measure tensile strength, electrical impedance, and microwave absorption in the 2–20 GHz range, co-deposited nanographite was mixed in a silicone rubber matrix and molded into 1.00–2.00 mm thick nanocomposite sheets. The nanocomposite sheets demonstrated a − 15 dB reflection loss in the 9–13 GHz frequency band with an absorber thickness of 1.24 mm. [ABSTRACT FROM AUTHOR]

WC-10Co-4Cr/Fe-based amorphous composite coatings with different WC-10Co-4Cr powder contents (0-12 wt.%) were prepared on C45 steel by plasma spraying. The microstructure, hardness, wear resistance and corrosion resistance of the WC-10Co-4Cr/Fe amorphous composite coatings were studied. The results show that, with the increase of WC-10Co-4Cr mass fraction, the microhardness and the porosity decrease firstly and then increase slightly. The study of the wear resistance shows that the wear resistance of the WC-10Co-4Cr/Fe-based amorphous composite coatings is higher than that of the single iron-based amorphous coating, and the wear resistance of the 9 wt.% WC-10Co-4Cr/Fe-based amorphous composite coating is the highest, which is about 1/4 of the wear rate of the sing-based amorphous coating. In the whole wear process, fatigue wear is dominant, accompanied by oxidation wear. Furthermore, electrochemical test results indicate that the corrosion resistance of the WC-10Co-4Cr/Fe-based amorphous composite coatings is higher than that of the single iron-based amorphous coating. The polarization resistance of the 9 wt.% WC-10Co-4Cr/Fe-based amorphous composite coating is the highest, about 7975.94 ± 375.42 Ω cm2, which is about 3 times that of the single iron-based amorphous coating (2547.84 ± 256.05 Ω cm2). [ABSTRACT FROM AUTHOR]

In the context of increasing pollution of almost all environmental media, there is a need for efficient and sustainable techniques to remove contaminants. Here, we review the biochar-supported nano-zero-valent iron composites with focus on their synthesis from wood, sludges and agricultural waste, and on their application to the removal of heavy metals in waters and soils. We also discuss removal mechanisms. We observe that metal removal rates of 90% and above can be achieved. The composite performance is influenced by the biochar feedstock, the pyrolysis temperature, generally within 300–1000 °C, and the iron/carbon ratio, e.g. 4:1, 2:1, and 1:2. Removal mechanisms include adsorption, reduction, and co-precipitation. We also discuss the optimization of preparation methods, their application in real environments, and the removal mechanisms for complex pollutants. [ABSTRACT FROM AUTHOR]

As a new type of metal sheet, titanium/iron composite sheets are crucial in various fields. However, in the forming of the curved shells of the titanium/iron composite sheets with small thickness-to-diameter ratios, sidewall wrinkling is extremely easy to form, and it is hard to control. In this paper, an experimental setup for hydro-mechanical deep drawing was designed, and sidewall wrinkling on the hemispherical shell with a flat bottom and 0.47% thickness-to-diameter ratio of titanium/iron composite sheets was effectively suppressed while avoiding splitting. Mechanical and numerical analyses were conducted to reveal the deformation mechanism, and the effect of chamber pressure was studied. The forming defects, thickness, and stress distributions were determined to reflect the deformation behavior. Results show the greater the chamber pressure, the more significant the effect of wrinkling suppression. When the chamber pressure reaches 20 MPa, the sidewall wrinkles disappear. Enough hydraulic pressure can produce a strong backward-bulging effect, which increases the wrinkling suppression pressure and improves plastic deformation instability. Moreover, the stress state of the sidewall changes under the action of hydraulic pressure, thereby changing the in-plane deformation behavior. Thus, the wrinkles already formed in the earlier stage of sidewall formation were adjusted after contact with the punch. The forming process has considerable potential to fabricate thin-shell components. [Display omitted] • The sidewall wrinkling of a curved surface shell can be suppressed by hydroforming. • The influence of hydraulic pressure on the wrinkling suppression is carried out. • The formed wrinkles are corrected during the blank contact with the punch. [ABSTRACT FROM AUTHOR]

Due to wear and improper operation, many machine parts become useless, which is why issues of friction and wear remain constantly relevant across all industrial sectors. This paper presents the results of research on the microstructure and properties of a nanostructural composite coating containing solid lubricant. The coating was deposited from a mixture of nanostructural WC-12Co powder and nanostructural Fe3O4 powder using HVOF spraying. Despite significant differences in grain size and density of both powders, the deposited coating consisted of WC-12Co matrix containing evenly distributed Fe3O4. The XRD analysis of the coating confirmed the presence of both components and the presence of W2C, which resulted from the decarburization of WC due to the high temperature during the spraying process. Furthermore, the microstructure analysis of the coatings confirmed that they contained both nanostructural WC and Fe3O4 grains that were present in the feedstock. The coefficients of friction, microhardness, and wear of the nanostructured composite coatings were determined using an experimental binomial program. Based on the ANOVA conducted, it was determined that the most significant impact on the friction coefficient is the Fe3O4 content in the sprayed mixture, while the oxygen to propane ratio affects the microhardness. For the wear of nanostructural composite coatings, the most important parameter is the spraying distance. [ABSTRACT FROM AUTHOR]

The descaling roller is a significant component in steel rolling production. Under harsh service conditions, the descaling roller is subjected to the dynamic impact caused by high-pressure water erosion and a high-temperature billet descaling process for a long time. Under the harsh conditions of high temperature, strong wear, multi-cycle heat, force, flow, and multi-field strong coupling, the roller surface is prone to wear and corrosion failure, which affects the production cost and efficiency. Through plasma surfacing technology, a high-performance coating can be applied on the conventional metal surface to effectively improve its surface properties. It is important to carry out experimental research on the surface plasma surfacing of the descaling roller to prolong product life, improve product quality, and save cost. At present, the research on the 42CrMo scaler matrix plasma surfacing of nickel-based alloys with different WC contents is still lacking. In this paper, 70%NiCrBSi+30%WC powder and 40%NiCrBSi+60%WC powder were used as surfacing materials; plasma surfacing experiments were carried out on the 42CrMo matrix; and SEM, XRD, microhardness, friction and wear, and corrosion tests were carried out on the surfacing layer to evaluate the feasibility of preparing an ultra-high-hardness WC-particle-reinforced nickel-based alloy plasma surfacing layer on the descaling roller surface and to explore the WC hard phase dissolution behavior and complex secondary phase formation mechanism. The results show that γ(Fe/Ni), Fe-Ni, FeSi, Fe3C, and M7C3 are the main phases in the Ni/WC plasma surfacing layer. The diffusion and precipitation of elements occur in the molten pool, and complex secondary phases are formed in the surfacing layer. Compared with the 70%NiCrBSi+30%WC surfacing layer, the WC deposition phenomenon of the 40%NiCrBSi+60%WC surfacing layer has been significantly improved and has better hardness, wear resistance, and corrosion resistance. Based on the welding test, the correlation law between powder formulation, welding structure, and surfacing layer properties was revealed in this study, which lays a theoretical foundation for the preparation of high-performance coating on the descaling roller surface and has significant engineering application value and practical significance. [ABSTRACT FROM AUTHOR]

In this work, Fe-2Cu-0.8C-CaF2 self-lubricating composites with calcium fluoride solid lubricant (3 □ 12 wt.%) were examined for their friction and wear at 5 and 10 m/s, at 500 °C. Addition of CaF2 decreased density and hardness of composites. During sliding, materials gained weight due to oxidation. Compared to the base matrix (Fe-2Cu-0.8C), composites showed lower weight gain and lower coefficient of friction. Increase in porosity with CaF2 content increased oxidation resulting in higher weight gain and increased friction due to wear debris abrasion. Increase in speed reduced weight gain due to higher material loss. Adhesion was the dominant wear mechanism in base matrix; delamination and wear debris abrasion in composites. Temperature rise at sliding surfaces was theoretically estimated. Increase in speed increased temperature, which reduced friction due to softening and shearing of solid lubricant. Composite with 3 wt.% CaF2 showed least surface damage and 6 wt.% showed lowest coefficient of friction, i.e., lower by 16% and 10% at 5, 10 m/s than base matrix. Tribological response of the composites to a broad range of applied parameters, viz. speed, load and temperature taken from earlier works and present work is briefly summarized. The study suggests the dominant role of CaF2 content and the wear debris in altering the tribological response. Further, the stability of the developed composites at high temperature and high load conditions was also established. The study suggests that the developed composites could serve high-load and high-temperature applications for heavy machinery such as bearings, shafts and gears. [ABSTRACT FROM AUTHOR]

In this work, iron based 1, 3, 5-tricarboxylic acid (FeBTC) was prepared via microwave-assisted method and incorporated into TiO2 via ultrasonic assisted method. The TiO2–FeBTC nanocomposites were characterized by XRD, FTIR, Raman, BET, FESEM, HRTEM, TGA, UV‒vis DRS and PL to understand their crystallographic, surface morphology, and optical characteristics. The Raman spectra showed a blue shift of Eg, A1g, and B1g peaks upon incorporation of FeBTC MOF onto TiO2. HRTEM and XRD analysis confirmed a mixture of TiO2 nanospheres and hexagonal FeBTC MOF morphologies with high crystallinity. The incorporation of FeBTC onto TiO2 improved the surface area as confirmed by BET results, which resulted in improved absorption in the visible region as a results of reduced bandgap energy from 3.2 to 2.84 eV. The PL results showed a reduced intensity for TiO2–FeBTC (6%) sample, indicating improved separation of electron hole pairs and reduced recombination rate. After fabrication of the TiO2–FeBTC MOF photoanode, the charge transfer kinetics were enhanced at TiO2–FeBTC MOF (6%) with Rp value of 966 Ω, as given by EIS studies. This led to high performance due to low charge resistance. Hence, high power conversion efficiency (PCE) value of 0.538% for TiO2–FeBTC (6%) was achieved, in comparison with other loadings. This was attributed to a relatively high surface area which allowed more charge shuttling and thus better electrical response. Conversely, upon increasing the FeBTC MOF loading to 8%, significant reduction in efficiency (0.478%) was obtained, which was attributed to sluggish charge transfer and fast electron–hole pair recombination rate. The TiO2–FeBTC (6%) may be a good candidate for use in DSSCs as a photoanode materials for improved efficiency. [ABSTRACT FROM AUTHOR]

The global presence of pharmaceutical pollutants in water sources represents a burgeoning public health concern. Recent studies underscore the urgency of addressing this class of emerging contaminants. In this context, our work focuses on synthesizing a composite material, FexOy/MAF-32, through a streamlined one-pot reaction process, as an adsorbent for diclofenac, an emerging environmental contaminant frequently found in freshwater environments and linked to potential toxicity towards several organisms such as fish and mussels. A thorough characterization was performed to elucidate the structural composition of the composite. The material presents magnetic properties attributed to its superparamagnetic behavior, which facilitates the recovery efficiency of the composite post-diclofenac adsorption. Our study further involves a comparative analysis between the FexOy/MAF-32 and a non-magnetic counterpart, comprised solely of 2-ethylimidazolate zinc polymer. This comparison aims to discern the relative advantages and disadvantages of incorporating magnetic iron oxide nanoparticles in the contaminant removal process facilitated by a coordination polymer. Our findings reveal that even a minimal incorporation of iron oxide nanoparticles substantially enhanced the composite's overall performance in pollutant adsorption. [ABSTRACT FROM AUTHOR]

The high-temperature interaction between molten gray cast iron and Ti + C substrates that are composed of titanium and graphite powders was investigated by the sessile drop method combined with the non-contact heating of an alloy/substrate couple to a test temperature of 1330 °C in an inert gas atmosphere (argon). During the high-temperature testing, the images of the couple were recorded by a high-speed high-resolution CCD camera and used for estimating the values of the contact angles over time. An analysis of the wettability kinetics of the different Ti + C substrates by molten cast iron as well as a detailed structural characterization of the solidified couples with the help of light microscopy, electron microscopy (SEM, TEM), X-ray diffraction, and energy-dispersive X-ray spectroscopy have allowed us to explain the mechanism of high-temperature interaction in the selected couples. It was evidenced that the good wetting and fast infiltration of all of the examined substrates with the selected alloy had a reactive nature due to the dissolution of the Ti and graphite in the molten alloy (dissolutive wetting) and the reactively formed wettable TiC phase. These high-temperature phenomena contributed to the formation of three metal-infiltrated zones with different amounts and distributions of TiC particles in the Fe-based matrix. [ABSTRACT FROM AUTHOR]

Recently, high-temperature composites reinforced with in-situ phases have been developed as a new class of composites for harsh environments. The behaviour of these composites under sudden heating and cooling conditions is greatly influenced by the type and fraction of components. The aim of this study is to investigate the microstructural properties and mechanical response of iron based composites after thermal shock cycling. The fabrication process involved in-situ powder metallurgy (IPM) sintering of Fe–B 4 C starting powders. The samples were subjected to thermal shock with a constant temperature differences (ΔT: 600 °C) and varied cycles (N: 1–50). Comparison of microstructural changes and mechanical behaviour before and after thermal shock has been carried out. The boron atoms released from the initial B 4 C generated diffusion zones in the matrix dominated by iron boride phases (Fe 2 B/FeB). An effective matrix-reinforcement interface has been created by in-situ powder metallurgy, where boride phases are almost homogeneously distributed in the iron matrix. While the hardness of the composites was significantly developed by the Fe 2 B/FeB phases, the addition of B 4 C resulted in a reduction in the coefficient of thermal expansion (CTE). The in-situ phases contributed in the minimisation of the coefficient mismatch by balancing the thermal expansion coefficients between iron and the initial B 4 C. Under the influence of thermal shock, microcracks and then macrocracks formed on the sample surfaces, increasing in width and depth with thermal cycles. This resulted in accelerated fracture damage under post-thermal loading. Both the impact and flexural strengths of the samples were significantly reduced as the number of thermal cycles increased. Although the 20% B 4 C reinforced composite provided maximum hardness, it showed poor resistance to thermal loading. The best results for mechanical loads were achieved by the 5% B 4 C reinforced composite, which showed no cracks even after 50 thermal cycling. [ABSTRACT FROM AUTHOR]

A method for obtaining composite surface-alloyed castings from gray cast iron SCh25 by cavityless casting with the use of master alloys containing chromium and ferroboron deposited as a paste layer on the surfaces of the casting molds is considered. The microstructure and the phase composition of the surface layer and the microhardness of the structural components are determined. Mechanical tests of the cast samples for compression and wear are carried out. Self-propagating high-temperature synthesis is shown to occur between the components of the master alloys deposited on the surfaces the molds during the production of the castings. The types and compositions of the borides and carboborides formed in the alloyed layer are determined. The effect of the parameters of the alloyed layer on the properties of the composite castings is analyzed. [ABSTRACT FROM AUTHOR]

This study investigated how process parameters of laser cladding affect the microstructure and mechanical properties of WC-12Co composite coating for use as a protective layer of continuous caster rolls. WC-Co powders, WC-Ni powders, and Ni-Cr alloy powder with various wear resistance characteristics were evaluated in order to determine their applicability for use as cladding materials for continuous caster roll coating. The cladding process was conducted with various parameters, including laser powers, cladding speeds, and powder feeding rates, then the phases, microstructure, and micro-hardness of the cladding layer were analyzed in each specimen. Results indicate that, to increase the hardness of the cladding layer in WC-Co composite coating, the dilution of the cladding layer by dissolution of Fe from the substrate should be minimized, and the formation of the Fe-Co alloy phase should be prevented. The mechanical properties and wear resistance of each powder with the same process parameters were compared and analyzed. The microstructure and mechanical properties of the laser cladding layer depend not only on the process parameters, but also on the powder characteristics, such as WC particle size and the type of binder material. Additionally, depending on the degree of thermal decomposition of WC particles and evolution of W distribution within the cladding layer, the hardness of each powder can differ significantly, and the wear mechanism can change. [ABSTRACT FROM AUTHOR]

Iron (Fe) has been considered a major impurity since it is detrimental to the mechanical properties of many cast aluminum alloys due to the formation of Fe-containing brittle intermetallic phases. Fe is found naturally as an impurity in bauxite ore, resulting in Fe contamination of aluminum alloys with increasing contamination from current recycling practices. The Al–Ce–Fe system was investigated using CALPHAD (CALculation of PHAse Diagrams) modeling and experimental casting techniques. It was found that additions of Fe to the Al–Ce system are beneficial to the strength (slightly) and ductility (significantly) of the ternary alloys, which is attributed to the formation of fine metastable Al8CeFe2 phase with aggregate morphology and equilibrium Al10CeFe2 phase, suppressing coarse proeutectic Al11Ce3 phase in near-eutectic Al–Ce alloys. Heat treatment study showed that the metastable Al8CeFe2 phase transforms to predicted equilibrium Al10CeFe2 phase at 500 °C, with essentially no intermetallic or grain coarsening; thus, the alloy displayed excellent property retention. The Al–Ce–Fe alloy system offers opportunities for sustainable, recyclable alloy development using low-cost Fe and low-cost cerium (a byproduct of rare-earth extraction). [ABSTRACT FROM AUTHOR]

Three-mm-diameter WC/HSS composites with different binders (Co and Co-Ni-Fe) were prepared. The effect of two different binders on the microstructure and properties of WC powder and HSS composites was compared to investigate the feasibility of substituting Fe and Ni for Co in WC and steel composites. The results show that the WC/HSS sample without binder has significant macropores at the interface, with a porosity of up to 43.76%. The porosity of the composite material containing Co binder is 6.07%. The partial substitution of Ni and Fe for Co significantly reduces the shrinkage temperature of WC powder, and the porosity was reduced to 0.77%. The addition of Ni and Fe in WC facilitates the mutual diffusion among Cr, Mo, and Co elements and the interface bonding between WC and HSS. After adding Ni and Fe elements, the microhardness of the WC/HSS composite materials is slightly lower than that of the Co-added composites, with a microhardness of 1204 HV in the WC region. The HSS microhardness remains almost constant during the binder substitution, maintaining around 600 HV. The wear resistance of the composite outer layer can be effectively enhanced by the use of Co, Ni, and Fe additives. [ABSTRACT FROM AUTHOR]

The adsorption behavior and synthesis of a chitosan microsphere composite with iron nanoparticles (Ch‐Fe) for the removal of arsenates [As(V)] from aqueous solutions were investigated. First, the chitosan microspheres (Ch‐SD) were obtained using the Spray Dryer volatilization technique (SD), optimizing their particle size. Then, the iron nanoparticles (Fe‐NPs) were prepared using the microwave precipitation technique. The composite was characterized, and the arsenate adsorption parameters were determined through batch‐type experiments. Significantly fast adsorption rates were observed for both adsorbents. Besides, Ch‐Fe and Ch‐SD effectively removed arsenates over a wide pH range. The hydroxyl and amino functional groups are involved in removing arsenates. The Pseudo‐second order and the Elovich models described arsenate kinetic sorption data for Ch‐Fe and Ch‐SD, respectively. The As(V) maximum adsorption capacities were 27.46 mg/g and 29.94 mg/g for Ch‐SD and Ch‐Fe, respectively, increasing significantly at elevated temperatures. The Langmuir‐Freundlich model adequately described the isothermal data for both materials, suggesting adsorption heterogeneity. The composite's surface impregnation with Fe‐NPs enhanced the Ch‐SD adsorption properties. The SD method was suitable for obtaining the chitosan/Fe‐NPs microspheres and effectively removed As(V) from aqueous solutions. [ABSTRACT FROM AUTHOR]

In this study, carbonyl iron powder (CIP) with an average particle size of 3–4 µm made by the thermal decomposition of iron pentacarbonyl Fe(CO)5 was subjected to annealing in an oxidizing environment at 200–400 °C and CIP was ball-milled to transform from spherical to flake morphology. The particle morphology, oxidation state, dielectric, magnetic, and electromagnetic wave absorption characteristics were investigated. The results revealed that for the as-made CIP complex permittivity, permeability, attenuation, impedance matching, and reflection loss consistently increased from 60 to 80% weight addition in wax, whereas for the flake morphology, the subject characteristics were compromised. For the annealed CIP samples, the complex permittivity increased with increasing temperature causing enhanced polarization loss, whereas the complex permeability decreased with oxide formation. Significant improvements in impedance matching and microwave absorption performance were achieved for samples annealed at 200 and 250 °C. The as-made CIP exhibited an effective absorption bandwidth (EAB) of 6.4 GHz with a thickness of 1.5 mm, demonstrating a minimum reflection loss (RLmin) of − 32 dB. For the CIP sample annealed at 200 °C, the EAB (RL < − 10 dB) is 8.32 GHz at a thickness of 1.5 mm, whereas the 250 °C-annealed CIP presents an EAB (RL < − 10 dB) 7.94 GHz at thickness of 1.5 mm. This study presents advancements in the field of microwave absorption for practical stealth applications to reduce the radar cross-section to a thin thickness and ultrawide absorption bandwidth. [ABSTRACT FROM AUTHOR]

In this paper, preforms with three-dimensional structures and different thicknesses were constructed by 3D printing technology, and WC particle reinforced high-chromium cast iron (HCCI) composites was prepared by infiltration casting method. The microstructure of the WC/Fe matrix composites was investigated using scanning electron microscopy (SEM), energy spectroscopy (EDS), X-ray diffraction (XRD) and electron backscattered diffraction (EBSD). The effects of different preform wall thickness on the hardness and three-body abrasive wear properties of the composites were tested. The results showed that with the increase in the wall thickness of the three-dimensional preform from 2.5 to 10 mm, the volume of the composite zone formed by the dissolution diffusion reaction of WC and HCCI gradually increased from 31.8 to 41.2%. The microstructure was composed of composite zone, matrix and WC particles partially dissolved. The hardness of the composite zone increased at first and then decreased, while the wear weight loss of the composite showed an opposite trend. Compared with the wall thickness of 2.5 mm, the minimum wear weight loss of the composite was 0.2821 g for a wall thickness of 7.5 mm, and the wear resistance was improved by 12.8%. The hardness and wear resistance of WC/Fe matrix composites at different wall thicknesses were mainly related to the diffusion of the preform and the formation of the composite zone. [ABSTRACT FROM AUTHOR]

Composites of honeycomb-structured high-chromium cast iron matrix reinforced with zirconia-toughened alumina particles (ZTAP) were successfully fabricated by a non-pressure infiltration casting process. Different preform hole patterns were designed in this study, following the principle of keeping the same area of the honeycomb holes with the same outline size. The hardness and modulus continuously increased from the high-chromium cast iron matrix through the interfacial layer to the ZTA ceramic particle. The residual thermal stress in the samples with the circle hole pattern was the lowest at 389.7 ± 20.2 MPa. The wearing volume loss of the composites with the regular hexagon pattern was minimal after four periods. [ABSTRACT FROM AUTHOR]

Green nanotechnology has gained attraction in recent years due to the growing awareness of the environmental and health risks associated with traditional methods of nanomaterial synthesis. In the present study, nanocomposite (NCs) of silver and Iron were prepared using Zanthoxylum Armatum seeds aqueous extract which acts as a reducing, stabilizing, and capping agent. The synthesized NCs were characterized using UV/Vis Spectroscopy, powder X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and EDX. The UV/Vis spectroscopy analysis of the NCs revealed the presence of a surface plasmonic resonance band occurring at 420 nm. Examination of the NCs through SEM demonstrated that they exhibited a nearly spherical morphology, with an average particle diameter measuring 54.8 nm. The crystalline nature of these NCs was verified through X-ray diffraction (XRD), and the calculation of crystallite size using the Scherrer-Debye equation yielded a value of 12.6 nm. The adsorption ability of newly synthesized nanocomposites was investigated against Acid Black 234 Dye. The results showed that a 0.5 g of NCs dose at pH 4 removed 99.3% of 10 mg/L of Acid Black 234 Dye within 60 min. Based on the findings of this research, it can be inferred that the that Ag-Fe NCs synthesized from Zanthoxylum Armatum seeds aqueous extract hold significant potential for addressing environmental pollution caused by Acid Black 234 Dye. The NCs were used as adsorbent for the removal of Acid Black 234 dye from the wastewater sample and showed 98% removal of dye from the commercial sample within 60 min. In this context, the research highlights that the environmentally friendly synthesis of Ag-Fe nanocrystals (Ag-Fe NCs) using Zanthoxylum Armatum as a mediator offers an efficient and cost-effective solution for mitigating environmental pollution. [ABSTRACT FROM AUTHOR]

This study proposes the thermal decomposition of salt compounds and doping of carbonyl iron powders (CIPs) to optimize the preparation of an insulating layer through the solid-phase interface reaction. First, (Fe–Si–Cr + CIPs)/ZnSO4 composite powders were synthesized using the hydrothermal method and (Fe–Si–Cr + CIPs)/ZnO·SiO2·Cr2O3 SMCs with a ZnO·SiO2·Cr2O3 composite insulation layer were prepared through heat treatment and cold pressing. The effect of the CIP doping content on the microstructure and magnetic properties of the (Fe–Si–Cr + CIPs)/ZnO·SiO2·Cr2O3 SMCs were then investigated. During the heat treatment, ZnSO4 decomposed into solid ZnO and gaseous SO2 and O2. The O2 drives the solid-phase reaction, prompting the migration of nonmagnetic Si and Cr atoms from the interior of the Fe–Si–Cr soft magnetic powder to the surface insulation layer, finally forming the ZnO·SiO2·Cr2O3 insulation layer. The doped CIPs also show good plasticity during the coating process, combining with the coating layer to fill the internal pores of SMCs. Moreover, as the particles are small with a high surface area, they increase the number of reaction sites for ZnSO4 decomposition and facilitate the growth of the composite insulation layer, promoting its uniform distribution on the surfaces of the soft magnetic powders and CIPs. The lattice mismatch between the insulation layer and soft magnetic powder is reduced while the magnetic-phase content is increased, allowing the effective doping of CIPs sin the insulation layer. The magnetic properties of SMCs can be precisely regulated by changing the doping amount of CIPs. Unlike other insulating layer–preparation strategies based on the interfacial solid-phase reaction, the proposed method exploits the high plasticity and specific surface area of CIPs and removes the lattice mismatch between the insulation layer and soft magnetic powder. [ABSTRACT FROM AUTHOR]

This work emphasizes an innovative approach utilizing 3D imaging technology based on synchrotron radiation to assess the microstructure of second-phase iron particles and the porous structure within 3D-printed PLA/magnetic iron composites at different printing angles. The study examines how these observations relate to the material's ductility when processed using fused filament fabrication. In particular, this study examines the impact of one processing parameter, specifically the printing angle, on the microstructure and mechanical behaviour of a polylactic acid (PLA)–iron (PLI) composite designed for magnetic actuation. Fused filament fabrication is employed to produce PLI tensile specimens, with varied printing angles to create different layups. X-ray microtomography is utilized to analyse the microstructure, while tensile mechanical properties are evaluated for all composites, with findings discussed in relation to printing angle conditions. Scanning Electron Microscopy is used to examine the fractography of broken specimens. Results indicate that the printing angle significantly influences the tensile properties and mechanical anisotropy of 3D-printed PLI composites, with an optimal 45°/45° layup enhancing tensile performance. These findings suggest that 3D-printed PLI composites offer a cost-efficient means of producing bio-sourced, light-adaptive materials with intricate magnetic actuation capabilities. By quantifying the modulation of mechanical properties based on printing parameters that influence microstructural arrangement, the research sheds light on a novel aspect of composite material characterization. [ABSTRACT FROM AUTHOR]

Centrifugal pumps are used extensively in various everyday applications. The occurrence of corrosion phenomena during operation often leads to the failure of a pump's operating components, such as the impeller. The present research study examines the utilization of composite materials for fabricating centrifugal pump components using additive manufacturing as an effort to fabricate corrosion resistant parts. To achieve the latter two nanocomposite materials, carbon fiber reinforced polyamide and carbon fiber reinforced polyphenylene sulfide were compared with two metal alloys, cast iron and brass, which are currently used in pump impeller manufacturing. The mechanical properties of the materials are extracted by performing a series of experiments, such as uniaxial tensile tests, nanoindentation and scanning electron microscope (SEM) examination of the specimen's fracture area. Then, computational fluid dynamics (CFD) analysis is performed using various impeller designs to determine the fluid pressure exerted on the impeller's geometry during its operation. Finally, the maximum power rating of an impeller that can be made from such composites will be determined using a static finite element model (FEM). The FEM static model is developed by integrating the data collected from the experiments with the results obtained from the CFD analysis. The current research work shows that nanocomposites can potentially be used for developing impellers with rated power of up to 9.41 kW. [ABSTRACT FROM AUTHOR]

The material extrusion 3d printing technique has proved to be reliable and low cost for obtaining metal parts. Therefore, in the present work, its suitability for obtaining pieces of a material composed of iron/iron oxide from an industrial waste was studied. Once the powder was obtained by chemical partial reduction, filaments were manufactured with a polymer matrix of TPE/PP/SA in a polymer–powder proportion of 13–87 wt.%. The influence of temperature and printing speed on the geometry of the printed and sintered parts, as well as on their mechanical and microstructural properties, was evaluated. The results showed that the printing speed had a significant impact on the print geometry of the parts, while the printing temperature had no effect. During thermal debinding and sintering, an additional chemical reduction due to the production of reducing agents during the decomposition of the polymer matrix was observed. This shows that the selection of the polymer matrix affects the microstructure of the sintered parts. [ABSTRACT FROM AUTHOR]

Magnetic iron oxide nanoparticles immobilized on microcrystalline cellulose (MCC) are studied for the adsorption of Pb(II) ions from an aqueous solution. Composites of iron oxide and MCC were synthesized with a 5%–20% loading of iron (w/w%). The effect of pH, concentration, and contact time was studied. The adsorption isotherms were fitted to nonlinear Langmuir, Freundlich, and Dubinin–Radushkevich (D‐R) isotherms, and kinetics were studied for pseudo‐first and second‐order kinetic fit models. Adsorption of Pb(II) ions increased with increasing pH value up to 5. Maximum adsorption of Pb(II) was observed up to 299.91 mg−1 in D‐R equilibrium for onto MCC‐Iron oxide composite for composite with iron loading of 20% at pH 5. [ABSTRACT FROM AUTHOR]

Al-9Si-0.6Mg matrix composites dual-reinforced with 20 wt.% SiC particles and three-dimensional iron foam (iron foam/SiC/Al-Si) were fabricated using vacuum semi-solid stirring and vacuum-assisted infiltration. The tribological behavior at elevated temperatures was investigated under different loading conditions. The dry sliding wear test revealed that the three-dimensional interpenetrating iron foam skeleton contributes to improved wear performance at elevated temperatures, owing to an increase in surface hardness and decrease in subsurface wear deformation caused by the bearing capacity and synergistic strengthening effect of iron foam during the sliding process. SEM analysis of the longitudinal section of the friction-affected layer of the iron foam/SiC/Al-Si composite demonstrated that the formation of a mechanically mixed layer can decrease wear loss. Wear rate, wear morphology, and debris morphology were correlated with wear mechanisms. The increased load promotes the propagation of horizontal cracks and delamination wear. The predominant wear mechanisms of the iron foam/SiC/Al-Si composite change from abrasive wear and a small amount of oxidation wear to delamination, adhesive wear, and plastic flow when the temperature reaches 350 °C. [ABSTRACT FROM AUTHOR]

This paper presents an ultra-wideband microwave absorber with a composite of carbonyl iron powder (CIP) and thermoplastic polyurethane (TPU) material and a wide-angle absorption stacked cross structure. The simulation results show that although the total thickness is less than 3.21 mm, the proposed device can achieve high absorption (over 90%) in the range of 7.55–100 GHz, and the total bandwidth is 92.45 GHz, with a relative bandwidth of 172%. In addition, the absorber is insensitive to the polarization characteristics of incident electromagnetic waves and can achieve a wide incident angle absorption of up to 60∘. [ABSTRACT FROM AUTHOR]

This study comprehensively investigated the effect of iron-oxide nanoparticles (NPs) on weathering durability and thermal resistance of wood-plastic composites (WPCs). The hydrophobic nature of NPs improved the dimensional stability of WPCs. The small size of NPs deposits the voids in the matrix, which helps to increase the mechanical properties, even after weathering test. The decrease of modulus of rupture (MOR) reached up to 16% for control samples, while it was 2% for IO40-1. Despite the intensive weathering conditions, NPs cover the surface of materials like a UV shield, improving WPCs' UV resistance. Moreover, the increase in the wood and NPs content limited the UV degradation, which resulted in lower color changes. The attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) analysis also proved that there were nearly no changes in the characteristic bands of polymer (2916 and 2846 cm−1) and wood (1512 cm−1). The microscopic investigation, however, revealed the deterioration on the surface of WPCs after weathering exposure. Even though UV degradation is inevitable, iron oxide NPs significantly preserved the WPCs surface. However, there were also crack formations, which were also inhibited. On the other hand, NPs decelerated the thermal degradation by acting as a heat barrier. Thermogravimetric analysis (TGA) analysis revealed an increase in the degradation temperature. Limit oxygen index (LOI) values also increased up to 27.6%, which demonstrated an improvement against flammability. [ABSTRACT FROM AUTHOR]

The field of P-band (0.3–1 GHz) absorption has witnessed rapid development in metamaterial absorbers due to their exceptional designability and the absence of restrictions imposed by the one-fourth wavelength rule. In this study, we combined carbonyl iron powder (CIP) composites with a periodic structure composed of metal capacitive patterns and employed a genetic algorithm (GA) to optimize the electromagnetic parameters of the CIP substrate. By selecting the appropriate shape and material for the units of pattern based on transmission line theory, as well as regulating relevant structural parameters, we successfully designed an ultra-thin broadband metamaterial absorber for the P-band. Experimental results demonstrate that within the range of 0.3–0.85 GHz, the reflection loss of our absorber remains below −5 dB, with a maximum value of −9.54 dB occurring at 0.45 GHz. Remarkably, this absorber possesses a thickness equivalent to only 1/293 of its working wavelength. Then, we conducted analyses on electric field distribution, magnetic field distribution, and energy loss density. Our findings suggest that high-performance absorption in metamaterials can be attributed to λ/4 resonant or coupling effects between structural units or diffraction phenomena. This absorber offers several advantages, including broad low-frequency absorption capability, ultra-thin profile, and convenient fabrication process, thus providing valuable theoretical insights for designing metamaterial structures. [ABSTRACT FROM AUTHOR]