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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]

In this study, we synthesized Fe3O4 nanoparticles (Fe3O4 NPs) of varying sizes and morphologies using the solvothermal method and incorporated them as additives into carbonyl iron magnetorheological fluids (CI-MRFs). We tested the shear stress, yield stress, viscosity and storage modulus of the MRFs using a magnetorheometer to investigate how the size and morphology of Fe3O4 NPs influence the performance of MRFs. Our results indicate that the size of the additive nanoparticles significantly enhances the MR properties of MRFs more than their morphological attributes. This enhancement results from optimizing and stabilizing the CI magnetic chain structure of the nanoparticles in the presence of a magnetic field. Specifically, MRFs with Fe3O4 NPs averaging 250 nm in size exhibit higher yield stress and storage modulus and show increased resistance to shear strains. Although the nanoparticle morphology has a modest effect on the rheological properties of MRFs, hexahedral and octahedral particles can enhance rheological properties through increased internal friction compared to spherical particles. Additionally, Fe3O4 NPs of different sizes and morphologies improve the sedimentation stability of MRFs, with those around 250 nm being particularly effective at slowing down sedimentation. Both hexahedral and octahedral Fe3O4 NPs slow down sedimentation more effectively than spherical Fe3O4 NPs. This paper investigates the rheological properties of CI-MRFs by controlling the additive particle size and morphological features, providing a research foundation for the design and optimization of MRFs. [ABSTRACT FROM AUTHOR]

This work presents the study of effect of morphology of carbonyl iron, carbonyl iron-based, and e-waste-based mixtures on microwave absorption properties. Firstly, the flake shaped carbonyl iron particles and its mixture are prepared using conventional and efficient ball milling and blending method, respectively. It provides the absorption in lower frequency region. Further, the covered frequency range starts to shifts slowly towards higher frequency ranges due to the morphological changes. On the other hand, effect of complex morphology of e-waste-based mixtures are also studied. These heterogeneous mixtures are developed using the cutting mill and blending methods that can provide the absorption in higher frequency with very narrow bandwidth. In this manner, effect of morphology on single layer microwave absorption performance of developed heterogenous material is proposed. It is also explored that the developed samples cover a wider bandwidth by utilizing the multilayering technique. A three-layer absorber is designed using genetic algorithm and the results are also validated. The structural and morphological study of the developed heterogeneous materials has been done using X-ray diffraction (XRD) and Field Emission Scanning Electron Microscope (FESEM) analysis. Also, rigorous study has been done on magnetic properties and Cole-Cole plots to understand the magnetic and dielectric losses respectively occurring inside the materials. The results showed wide bandwidth absorption of 11.62 GHz (≤−10 dB bandwidth) in the lower frequency region ranges from 0.5 to 12.12 GHz (i.e., L, C, and X-band). The total thickness achieved is 1.85 mm which is very compact (<2 mm). Thus, a thin and wideband microwave absorber at lower frequency range using heterogeneous morphology of developed materials is also presented. The proposed microwave absorbing materials can be potentially utilized for the shielding applications. [Display omitted] • Study explores the impact of morphology on microwave absorption in heterogeneous mixtures. • Milled Carbonyl iron and its mixture exhibit absorption in lower frequency regions. • E-waste-based mixtures with complex morphology exhibit absorption in higher frequency regions. • Multilayering techniques extend bandwidth, with a three-layer absorber designed using genetic algorithms. • Wideband absorption (11.62 GHz) achieved in the lower frequency range (0.5–12.12 GHz) at a compact (<2 mm) thickness. [ABSTRACT FROM AUTHOR]

Three sets of gelatin-glutaraldehyde hydrogels and ferrogels have been synthesized and studied using Small Angle Neutron Scattering (SANS) and, FTIR and Raman spectroscopy. Cross-linker (viz. glutaraldehyde) and dopant (viz. carbonyl iron) concentrations are found to affect the correlation length and water content of the samples. The basic network structure of the hydrogels and ferrogels is similar. The carbonyl iron particles are not chemically bonded to the network but are dispersed across it. Their presence causes re-arrangement of the cross-links and polymer segments in the ferrogels. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

It was considered the forming multilayer heat-resistant coatings that work under conditions of elevated temperatures and long-term oxidation. The issue of increasing the service life of the parts by strengthening their bulk and surface is considered. The issue of determining the level of the thermophysical properties is also considered. The thermophysical properties of carbonyl iron reinforced with carbon fibers (CF) pre-clad with nickel are investigated. Unclad and nickel clad carbon fibers were produced. The thermal conductivities of the samples are determined depending on the conditions of their production. The thermal conductivity characteristics of polymer composite materials based on CF with ceramic hollow microspheres and carbonyl iron from CF depending on the conditions of their production were determined. It is shown that heat transfer mechanisms related to the electron-lattice interaction can function in these systems. Heat transfer can occur by various transport mechanisms, such as collisions or diffusion. Nevertheless, the increase in thermal conductivity can be related to the electronic mechanism. The thermal conductivity of materials based on carbonyl iron with nickel-plated CF is 1.2 times higher compared to unclad CF, which is due to better adhesive interaction between the coated carbon fibers and iron was established.

In this study, simultaneous tunable flame retardant and water-repellent properties were imparted into polyester fabrics using nano carbon black (NCB) and micro carbonyl iron (CIP) particles through the pad-dry-cure method. Various treatments were applied including the individual use of CIP and NCB, step-by-step application of NCB followed by CIP, and use of NCB/CIP in one single-step method. The morphology and crystalline structure of the treated fabrics were characterized by FE-SEM and XRD. Also, a direct vertical flame test was used for evaluating the flame retardant properties of the fabrics. Further, both static and dynamic methods were considered to study the hydrophobic properties of the treated fabrics. The effect of sunlight irradiation on the water adsorption time of the treated fabrics was also investigated. Findings suggested the higher potential of step-by-step application of NCBs and CIPs, producing a reasonable reduction in the burning length and maximum static contact angle of 142°, along with more maximum force tolerable in the tensile strength test. [ABSTRACT FROM AUTHOR]

The study of samples of multicomponent epoxy composites (CM) was carried out, the structure, morphology of fillers and their distribution in the epoxy matrix were studied, the features of the process of modifying the conductive cluster and changing the interphase polarization due to the integration of nanocarbon (graphite nanoplates GNP, carbon nanotubes CNT) and inorganic (Fe, Co3О4) of superdisperse fillers, the influence of the composition, morphology and concentration of combined fillers on the electrodynamic characteristics of composites and the mechanisms of electrical transport in CM was determined. As shown by studies of the phase composition of magnetic powders by the X-ray diffraction method, cobalt oxide nanopowder consists of a pure Co3O4 phase, and carbonyl iron – of pure α-Fe. Experimental research of electrical resistance was carried out on direct current in the temperature range of 77-293 K. As studies have shown, the electrical conductivity of CM has a percolation character, that is, it increases sharply at a certain concentration (weight Сcr or volume ψc) of the nanocarbon filler. The addition of inorganic fillers along with nanocarbon fillers leads to a change in the nature of the percolation curves. Changes in the electrical conductivity of three-phase CMs significantly depend on the size and morphology of nanocarbon particles. The addition of nanocarbon filler GNP along with inorganic magnetic particles Со3О4 or Fe led to a decrease in the percolation threshold and a higher electrical conductivity of CM at a GNP content higher than 3 wt. %. When adding Co3O4 particles along with CNTs to the epoxy matrix, there are significant changes in the electrical conductivity at a CNT content of 1-5 wt. % was not observed. The nature of the temperature dependence of the electrical resistance is different depending on the type and content of the two-component filler in the CM. For epoxy CMs with high electrical resistance, a significant decrease in electrical resistance is observed when heated from 77 to 293 K. It was found, that the addition of 2-5 wt. % of graphite nanoparticles along with Co3O4 nanoparticles decreases the effective Young modulus and the compression strength of three-phase composites compared with Co3O4/epoxy. 5CNT/Co3O4/epoxy CM showed the minimal value of Young modulus (520 MPa) and enhanced flexible properties compared with composites with GNP/Co3O4 filler. The significant decrease in electric resistance (by 2 orders of magnitude) under uniaxial compression was found for 3GNP/Co3O4/epoxy CM with nanocarbon content close to the percolation threshold. The sufficiently lower reversible decrease of electrical resistance (not exceed 30 % relative to the initial value) was observed for 5 %GNP/Co3O4/epoxy composite. [ABSTRACT FROM AUTHOR]

In order to develop carbonyl iron-enhanced electromagnetic wave-absorbing composites, this paper utilizes two different morphologies of carbonyl iron powder (CIP), spherical and flake-like, which are blended with aqueous polyurethane (PU) in three different ratios to prepare impregnating solutions. Polyester (PET) needle-punched nonwoven materials are impregnated with these solutions to produce electromagnetic wave-absorbing composites. First, electromagnetic parameters of the two CIP particle types, spherical carbonyl iron (SCIP) and flake-like carbonyl iron (FCIP), are tested with the coaxial method, followed by calculation of the results of their electromagnetic wave absorption performance. Next, the composites are subjected to microscopic morphology observation, tensile testing, and arched frame method electromagnetic wave absorption performance testing. The results indicate that the microwave absorption performance of FCIP is significantly better than that of SCIP. The minimum reflection loss value for F3, a kind of FCIP-modified nonwoven fabric, at the thickness of 1 mm, at 18 GHz is −17 dB. This value is even better than the calculated RL value of CIP at the thickness of 1 mm. The anisotropic shape of flake-like magnetic materials is further strengthened when adhering to the surface of PET fiber material. Additionally, the modified composites with carbonyl iron exhibit higher tensile strength compared with pure PET. The addition of fibrous skeletal materials is expected to enhance the impedance matching of flake-like magnetic particles, forming a wearable and microwave-absorbing composite. [ABSTRACT FROM AUTHOR]

Owing to its excellent electronic properties, Ti3C2Tx MXene is an emerging class of two-dimensional nanomaterials that have a promising electromagnetic (EM) wave function; however, poor impedance matching has limited the application of these materials in absorption-dominated EM interference (EMI) shielding. Hence, the investigation of thin MXene nanosheet-based film materials for application to absorption-dominated EMI shielding, which produces less EM pollution than reflection-dominated EMI shielding materials, is essential. In this study, a Ti3C2Tx/carbonyl iron–aramid hybrid film possessing absorption-dominated EMI shielding properties was prepared by using flower-like core–shell Ti3C2Tx/carbonyl iron microspheres (Ti3C2Tx/CIs) and aramid nanofibers. In the X band, the EMI shielding effectiveness of the films reached 31.9 dB with a lower SER value (below 3 dB), which means that less than 50% of the reflected incident waves and secondary EM pollution were reduced by the EMI shielding film materials. These results were attributed to superior impedance matching and multiple dissipation mechanisms of the Ti3C2Tx/CIs nanocomposites, which substantially enhanced the EM-wave absorption properties of a single MXene. The experimental results indicated that Ti3C2Tx/CIs nanocomposites showed a minimum reflection loss of −50.8 dB at 7.84 GHz. Moreover, a maximum effective absorption bandwidth of 5.5 GHz (12.48–18 GHz) was obtained at 1.60 mm, almost covering the entire Ku band. Therefore, this work provides a framework for designing MXene-based absorption-dominated EMI shielding nanocomposites. [ABSTRACT FROM AUTHOR]

In this study the graphene oxide modified carbonyl iron (GO‐CI) was prepared by γ‐ray irradiation, which was added to silicone rubber composites to enhance the nuclear radiation shielding performances. X‐ray diffraction (XRD) characterization result showed the structure and morphology of the obtained GO‐CI nanocomposites. The mixture of GO/CI and the hybrid GO‐CI were individually incorporated into the vinyl‐terminated polydimethylsiloxane (Vi‐PDMS) to prepare referenced SR/GO/CI and SR/GO‐CI composites. Compared with SR/GO/CI, the SR/GO‐CI exhibited better thermal conduction and mechanical recovery properties. Moreover, the γ‐ray radiation shielding ability of SR/GO‐CI is much higher than that of pristine SR/GO/CI. CI particles are coated by GO nanosheets to increase surface area to prevent sedimentation of CI. It implies that SR‐GO/CI composite would have potential application as the radiation hardening material with thermal conductive and nuclear radiation shielding function. [ABSTRACT FROM AUTHOR]

With the development of microwave technology and the widespread use of high-frequency electronic equipment, electromagnetic pollution is becoming increasingly serious. The research and development of electromagnetic protection technology and lightweight broadband microwave absorption materials are urgent. In this work, the lightweight and porous tellurium-doped black phosphorus nanoflakes/aramid nanofibers/carbonyl iron nano-powder aerogel (TBAC) was prepared by vacuum extraction and freezing drying method. The low conductivity of TBAC aerogel exhibited a unique dielectric dispersion phenomenon, where the imaginary part of the permittivity spectrum displayed a strong resonance peak. It resulted in the wavelength of the microwave inside the medium no longer decreasing monotonically with frequency, providing new ideas for expanding the microwave absorption bandwidth. Strong magnetic carbonyl iron nanopowders were devoted to adjust the impedance characteristics of the composites by changing the content, achieving strong absorption. Aramid nanofibers were used to prepare porous aerogel, and acted as an adhesive instead of paraffin. Porous aerogel realized the material ultra-lightweight (0.02–0.043 g/cm3), while enhancing the polarization of the medium, as well as the multiple reflection of microwaves. By uniformly dispersing Te-BP and carbonyl iron in ANF aerogel, TBAC-1-3 aerogel exhibited the minimum reflection loss (RL min) of −55.1 dB and an effective absorption bandwidth (EAB) of 6.55 GHz with the thickness of 1.7 mm. Additionally, the ultra-broadband EAB of 8.46 GHz under single thickness of 1.9 mm was obtained. Therefore, the ultra-lightweight TBAC aerogel offer a high-performance solution for ultra-broadband microwave absorption. [ABSTRACT FROM AUTHOR]

The paper presents the results of eight magnetorheological (MR) fluids of different compositions. Magnetite and carbonyl iron were used as magnetic particles. MR fluids based on glycerin and OKS 352 oil were produced using stabilizers in the form of oleic acid and Aerosil 200 (Evonik Resource Efficiency GmbH, Hanau, Germany) silica; additives such as graphite and yellow dextrin were also used. The aim of the study was to determine the properties of various combinations of components on the dynamic properties of MR fluids, i.e., properties characterizing the fluid within the range of low deformations, as well as to investigate the effect of different compositions on structural yield stress and flow stress prepared MR fluids at different magnetic field induction values. [ABSTRACT FROM AUTHOR]

For obtaining the ecofriendly microwave absorbing composites, flake carbonyl iron was mixed to the flotation carbon waste of titanium slag by ball-milling processes. The composites of 4 h ball-milling present excellent microwave absorbing performance of minimum reflected loss (RL) of −54.9 dB at 7.8 GHz with thickness of 2.6 mm. The same composites provide the performance of RL < −10 dB with the thickness from 1.2 mm to 5 mm at corresponding matching frequency from 3.3 GHz to 18 GHz. It means that the absorbing peak can be tunable at the wide frequency range with only adjusting the thickness. The strong absorbing intensity and wide tunable frequency range are attributed to the proper impedance matching of dielectric property from flotation carbon waste of titanium slag and magnetic property from carbonyl iron. Also, this work provides a research approach for handling industrial waste which contains carbon. [ABSTRACT FROM AUTHOR]

The paper explores the possibilities of using carbonyl iron in the form of a powder for the manufacture of radar-absorbing paints e reducing the radar signature of the objects that they cover. The attenuation values in the range of 4e18 GHz for various coating thicknesses, ranging from 0.5 to 2.00 mm with 0.5 mm increment, and for different absorber content -75% and 80%, as well as the use of two different binders in the form of epoxy resins with hardeners, were investigated. For the frequency of 18 GHz and a 1.5 mm thick coating with a 75% absorber content, Epidian 112 resin and Saduramid 10/50 hardener used as a binder, and the maximum attenuation level obtained equalled 20.2 dB at 16 GHz. Additionally, the absorber particle size ranging from 3 to 4 mm and its higher mass content resulted in achieving the reflection loss above -12 dB in the entire 8e12.5 GHz range for layers between 1- and 1.5 mm thickness. The qualitative assessment of the tested samples in the context of camouflage in the radar range was also performed, using statistical analysis. [ABSTRACT FROM AUTHOR]

In order to prepare a high-bandwidth absorbing material with both mechanical properties and electromagnetic absorption properties, a nano-particle modification and physical blending method were used to design and prepare a carbonyl iron room temperature vulcanized silicone rubber composite material based on polydimethylsiloxane. The mechanical properties and wave absorbing properties of the composite material were systematically analyzed. The results show that when the mass fraction of white carbon black is 3%, the composite material has the best comprehensive mechanical properties and is convenient for material processing; the composite material is a magnetic loss type wave absorbing material, and the attenuation constant of the material is positively correlated with the carbonyl iron content and frequency. According to simulation calculations, the absorption peak of electromagnetic waves gradually shifts to low frequency as the thickness of the composite material and the content of carbonyl iron are increased at 2-18 GHz. When the thickness of the composite material is 1.5 mm and the mass fraction of carbonyl iron is 75%, the effective absorption bandwidth of the absorbing material can reach 9.07 GHz, accounting for 56.68% of the target bandwidth. In practical applications, the formula can be optimized and the thickness of the material can be controlled according to the needs of the application scenario to achieve the best absorbing effect.

In the present work, we report that the manufacturing of new environmentally friendly and low-cost materials with electrical conductivity can be roughly and finely tuned by an external magnetic field for technical and biomedical applications. With this aim in mind, we prepared three types of membranes based on cotton fabric impregnated with bee honey, carbonyl iron microparticles (CI), and silver microparticles (SmP). In order to study the influence of the metal particles and the magnetic field on the electrical conductivity of membranes, electrical devices were made. Using the "volt-amperometric" method, it was found that the electrical conductivity of the membranes is influenced by the mass ratio ( m CI :   m SmP ) and by the B values of the magnetic flux density. It was observed that in the absence of an external magnetic field, adding microparticles of carbonyl iron mixed with silver microparticles in mass ratios ( m CI :   m SmP ) of 1:0, 1:0.5, and 1:1 causes the electrical conductivity of the membranes based on cotton fabrics impregnated with honey to increase 2.05, 4.62, and 7.52 times, respectively, compared with that of the membrane based on cotton fabrics impregnated with honey alone. When applying a magnetic field, the electrical conductivity of the membranes with microparticles of carbonyl iron and silver increases with increasing magnetic flux density B. We conclude that the membranes are very good candidates for the fabrication of devices to be used in biomedical applications due to the possibility of remote, magnetically induced release of the bioactive compounds from honey and silver microparticles into the area of interest during medical treatment. [ABSTRACT FROM AUTHOR]

In this work, we present the manufacturing process of magnetizable membranes based on cotton microfibers, honey, carbonyl iron, and three different concentrations of silver microparticles. Each membrane is used as a dielectric material for the fabrication of electrical devices. By using the plane capacitor method, the electrical capacitance and dielectric loss tangent are measured in a medium-frequency alternating field superimposed on a static magnetic field. From the obtained data, the time constants of the devices, the components of complex dielectric permittivity, and the electrical conductivity of the membranes as a function of the electric field frequency and magnetic flux density can be extracted. The results show that the obtained membranes can be useful for the fabrication of low-cost and environmentally friendly magneto-active membranes that are required for various technical and biomedical applications. [ABSTRACT FROM AUTHOR]

In order to break through the bottleneck of narrow effective absorption bandwidth (reflection loss RL ≤ −10 dB) of microwave absorbing materials, herein, we fabricate the metamaterials with carbon fiber (CF) and FeSi alloy (FSA) ribbon metastructure which is distributed in the carbonyl iron powders (CIP)/polyurethane (PU) matrix. The experimental results show that the microwave absorption capacity of the matrix can be significantly enhanced by CF. Compared with the pure matrix, the effective absorption bandwidth increases from 9.4–13.44 GHz to 11–16.8 GHz when the CF is parallel to the electric field vector and the spacing between adjacent CF is 20 mm. Furthermore, the CF and FSA ribbons are arranged in the matrix as an orthogonal arrangement, and the best absorption bandwidth cover 9.76–14.46 GHz when the electric field is parallel and 9.96–14.1GHz when the electric field is vertical when the spacing is 30 mm. The electromagnetic simulation of the metamaterials is calculated, it is proved that the increase of effective absorption bandwidth is due to the strengthening of carbon fiber and its coupling with FSA ribbon. This paper provides a new research path for improving the absorption properties of thin layer microwave absorbing materials. [ABSTRACT FROM AUTHOR]

Magnetorheological elastomers (MREs) are smart materials whose mechanical properties can quickly respond to changes in the external magnetic field. This phenomenon is known as the magnetorheological (MR) effect and is the key to the application of magnetorheological elastomers. Previous studies have found that the interface between magnetic particles and elastomers is a critical factor that influencing the MR effect of MREs. To improve the interfacial interaction between silicone rubber (SR) and carbonyl iron (CI) particles, in the MREs considered in this work, CI particles were subjected to surface modification through polydopamine (PDA) deposition and n-dodecyltrimethoxysilane (DTMS) grafting. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed the successful deposition of PDA@DTMS coating layer with a thickness of about 30.6 nm. The tensile strength of anisotropic MREs increased by 31.5% after surface modification of CI particles. The study of magnetic field induced changes in viscoelastic properties showed that CI-PDA@DTMS based MREs exhibited a superior MR effect to the CI-based MREs.

The paper presents the results of research on the rheological properties of magnetorheological (MR) fluids with different physical and chemical compositions. The research concerned complete compositions of MR fluids as well as base fluids (samples containing no particles with ferromagnetic properties). Magnetorheological fluids consisted mainly of a carrier liquid in the form of glycerin or OKS 352 silicone oil, with magnetite or iron pentacarbonyl particles. The paper demonstrates the effect of the selection of individual components of the MR fluids on their rheological properties, paying attention to the interaction of the base liquid with the particles of the solid phase of the MR fluid. Under the conditions of exposure to a magnetic field, the type of ferromagnetic particles (their magnetic properties) have a decisive impact on the magnetorheological response of the fluid (change in rheological properties due to the effect of the magnetic field on the fluid). The magnetite-based samples showed a tangential stress of 1000 Pa, while the use of iron carbonyl allowed to obtain approximately 8000 Pa (with respect to the case where B = 500 mT, γ • = 100 s − 1 ). No significant differences in rheological properties were recorded between the oleic acid- and silica-stabilized samples. [ABSTRACT FROM AUTHOR]

Novel radar-wave absorption nanocomposites are developed by filling the nanoscaled ferrites of strontium ferroxide (SrFe12O19) and carbonyl iron (CIP) individually into the highly flexible liquid silicone rubber (LSR) considered as dielectric matrix. Nanofiller dispersivities in SrFe12O19/LSR and CIP/LSR nanocomposites are characterized by scanning electronic microscopy, and the mechanical properties, electric conductivity, and DC dielectric-breakdown strength are tested to evaluate electrical insulation performances. Radar-wave absorption performances of SrFe12O19/LSR and CIP/LSR nanocomposites are investigated by measuring electromagnetic response characteristics and radar-wave reflectivity, indicating the high radar-wave absorption is dominantly derived from magnetic losses. Compared with pure LSR, the SrFe12O19/LSR and CIP/LSR nanocomposites represent acceptable reductions in mechanical tensile and dielectric-breakdown strengths, while rendering a substantial nonlinearity of electric conductivity under high electric fields. SrFe12O19/LSR nanocomposites provide high radar-wave absorption in the frequency band of 11~18 GHz, achieving a minimum reflection loss of −33 dB at 11 GHz with an effective absorption bandwidth of 10 GHz. In comparison, CIP/LSR nanocomposites realize a minimum reflection loss of −22 dB at 7 GHz and a remarkably larger effective absorption bandwidth of 3.9 GHz in the lower frequency range of 2~8 GHz. Radar-wave transmissions through SrFe12O19/LSR and CIP/LSR nanocomposites in single- and double-layered structures are analyzed with CST electromagnetic-field simulation software to calculate radar reflectivity for various absorbing-layer thicknesses. Dual-layer absorbing structures are modeled by specifying SrFe12O19/LSR and CIP/LSR nanocomposites, respectively, as match and loss layers, which are predicted to acquire a significant improvement in radar-wave absorption when the thicknesses of match and loss layers approach 1.75 mm and 0.25 mm, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this work, a highly efficient and environmentally friendly method for extracting palladium from hydrochloric acid media was developed. The method uses a magnetic sorbent carrying an organophosphorus extractant, which is not washed from the sorbent into the aqueous phase. The extractant was characterized by 1H, 13C, and 31P NMR spectroscopy and MALDI TOF mass spectrometry, and the palladium complex based on it was characterized by IR spectroscopy. According to an in vitro microbiological study, the extractant was non-toxic to soil microflora. It was established that the water uptake and saturation magnetization of the magnetic sorbent were sufficient for use in sorption processes. The sorption efficiency of palladium(II) with the developed sorbent can reach 71% in one cycle. After treatment of the spent sorbent with 5 M hydrochloric acid, palladium was completely extracted from the sorbent. The new sorbent is proposed for the extraction of palladium from hydrochloric acid media obtained by the leaching of electronic waste. [ABSTRACT FROM AUTHOR]

The development of microwave absorbing technology raises the demands for all-band absorption. The topological structures expand the frequency range of electromagnetic wave absorption and eliminate the differences caused by scattering in different incident directions. The multi-wall carbon nanotube and carbonyl iron particles were mixed with polylactic polymer to fabricate filaments for fused deposition. The distribution characteristics of the structures using carbonyl iron/carbon nanotube hybrid material for the key absorption frequency band are obtained. The reflectivity of the honeycomb structure in X and Ku bands is verified experimentally through the preparation method of fused deposition modeling 3D printing. With the decrease of the fractal dimension number, the electromagnetic loss performance basically increases. Preliminary research results showed that the topological structure could significantly expand the absorbing frequency range, and the effective frequency band less than −10 dB is 2–40 GHz, which has a clear application potential for radar absorption. [ABSTRACT FROM AUTHOR]

To improve dispersion stability and magnetorheological (MR) characteristics of carbonyl iron (CI) particles, we proposed novel hydrogel magnetic microspheres (MPs) dual-coated with alginate (AL) and chitosan (CTS) for the first time. The double-network structures formed by biological crosslinking and chelation reactions are capable to enhance its own structural stability and mechanical properties. The structural characterization, MR properties, and dispersion stability for different MPs were investigated. Additionally, the swelling behaviors were studied by swelling the dried MPs in the deionized water and sodium chloride solution, respectively. The results showed that the AL/CTS hydrogel core/shell MPs displayed the advantages of simple manufacturing, superior MR properties and deformability compared to pure micron-sized CI particles, indicating the improved dispersion stability of the MR fluids compared to that of the pure CI particles-based MR fluids. The introduction of double network structures with natural biopolymers will provide a new thought for the development of MR materials. [ABSTRACT FROM AUTHOR]

• The novel silicone modified epoxy resin was synthesized and used to encapsulate the carbonyl iron powders by in-situ polymerization method. • The reflection loss peak reached − 52.1 dB and effective absorption bandwidth achieved 7.8 GHz (10.2 GHz − 18 GHz). • The ER coating reduced Rp and CR, indicating corrosion inhibition and better adaptability to hostile environment. The novel silicone modified epoxy resin (ER) was synthesized and used to encapsulate the carbonyl iron powders (CIP) with core–shell structure by in-situ polymerization method. The silicone modified epoxy resin coating was introduced to enhance both microwave absorption and corrosion resistance of carbonyl iron. Microstructure analysis demonstrated that CIP were densely covered with ER shell. Hydroxyl (–OH) and amino group (–NH 2) present in silicone-modified epoxy resin, and chemically interact with the metal oxide layer on carbonyl iron to form covalent bonds or hydrogen bonds, improving interfacial adhesion and uniform dispersion of CIP. The ER shell effectively strengthens the microwave absorption ability and corrosion resistance of CIP. The reflection loss peak reached − 52.1 dB and effective absorption bandwidth achieved 7.8 GHz (10.2 GHz − 18 GHz). The epoxy resin coating significantly reduced the charge transfer resistance (R ct) and corrosion current density (J corr), indicating improved corrosion protection. Polarization resistance (R p) and corrosion rate (CR) analysis further verified corrosion resistance. The epoxy resin-coated CIP exhibit excellent microwave absorption and corrosion resistance, indicating widespread application in anti-electromagnetic interference field. [ABSTRACT FROM AUTHOR]

Gaining brilliant flexible, easily-processable, bendable, low-density and high electrical conductivity (σ) materials with an excellent electromagnetic-interference (EMI) shielding performance is urgently needed in the fields of aerospace, aircraft, military, wearable and portable electronic industries. Therefore, the growing desire towards miniaturizing and developing high-frequency electronics is increasing incredibly today and grabbing much attention, however, they cause extreme heat accumulation and EM radiations that affect their performances as well as their hazardous effects on human health. So, polymer nanocomposites with high thermal conductivity (k) and EMI shielding effectiveness (SE) synchronously are urgently required to consume the generated heat and blocks the EM waves. Herein, poly(vinyl alcohol)/graphene nanosheets/carbonyl iron (PVA/GR x /CIR 0.1-x) nanocomposite films are introduced as a new alternative candidate for EMI shielding applications with high in-plane k // , high mechanical functions, and EMI SE T performance. The synergistic effect of GR and CIR on EMI shielding functions, thermal stability, mechanical properties, electrical features, and surface morphology has been explored. The increase in GR(x) amounts provides continuous GR layers and dense networks for conducting electrons and heats, provides the films with an admirable k // and total SE (SE T) synchronously. Particularly, the PVA/GR 0.08 /CIR 0.02 films have shown an σ of 1.72 Sm−1, a large SE T of 32.94 dB and a specific SE (SSE/t) of 4365 dBcm2g−1 due to the mutual role (effect) of both high electrical conductive graphene and high magnetic carbonyl iron in cancelling the magnetic and electric fields of the incident EM waves. Moreover, the layered structure of GR endows films with a high k // of 3.62±0.11 W/(m·K), which is 14-fold larger than that of green PVA. The high compatibility and fine dispersion of GR/CIR fillers endow the films with a high Young modulus of 2.16 GPa, which is 7-fold larger than that of green PVA. This work suggests a novel and feasible scheme for producing high EMI shielding and high thermal conductive polymeric films, which will have huge prospects in advanced technology such as electromagnetic (microwave) interference shielding, wearable, biological, smart fabrics, military technologies and electronic equipments. [Display omitted] • Poly(vinyl alcohol)/graphene nanosheets/carbonyl iron films have been prepared for high k // and SE T functions. • PVA/GR/CIR films have recorded an σ of 1.72 Sm−1 at a very small amount 0.08 wt% of graphene. • PVA/GR/CIR films exhibited a large SE T of 32.94 dB and SSE/t of 4365 dBcm2g−1 at 0.08 wt% of graphene. • PVA/GR/CIR films exhibited a high k // of 3.62±0.11 Wm−1K−1 which is 14-fold larger than that of PVA. • PVA/GR/CIR films exhibited a high Young modulus of 2.16 GPa which is 7 times of pure PVA. [ABSTRACT FROM AUTHOR]

Most magnetic microwave absorption coatings are susceptible to corrosion under high-humidity, high-salt spray conditions, posing a significant threat to the survival and service life of maritime military equipment such as naval vessels. Therefore, the development of integrated stealth and anti-corrosion coatings is of paramount importance and urgency. This work presents an integrated coating utilizing a core-shell structured composite material (CIP@SiO 2 -M16) as the filler, based on the synergistic combination of M16 corrosion inhibitor and SiO 2 shell encapsulation of carbonyl iron core particles. Experimental results demonstrate that the SiO 2 shell on the surface of CIP, along with the chelation between adsorbed M16 and CIP, hinders the contact and reaction of corrosive ions with CIP. Simultaneously, the presence of the shell inhibits the formation of conductive pathways between CIP particles, leading to a reduction in the complex permittivity and optimizing impedance matching, allowing more electromagnetic waves to penetrate the coating's interior and be absorbed. As a result, this coating exhibits exceptional corrosion resistance and microwave absorption performance, with an electrochemical impedance of up to 2.38 × 109, over 1056 h of alternating salt spray exposure, and an unprecedented effective absorption bandwidth of 7.4 GHz at only 1.3 mm thickness, showcasing significant application potential. We believe that this coating's development opens up new avenues for research in the field of integrated stealth and corrosion resistance. • This work develops a microwave absorption coating with corrosion resistance using corrosion inhibitor for the first time. • Our coating exhibits an extraordinary absorbing band of 7.4 GHz at a thickness of 1.3 mm. • The Impedance modulus of materials reaches 2.38E9 after absorbing our synthesized corrosion inhibitor. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, magnetizable polyurethane sponges (MSs) were obtained from commercial absorbent polyurethane sponges (PSs) doped with carbonyl iron microparticles (CIPs). Based on MSs, we manufactured cylindrical capacitors (CCs). The CCs were subjected to both a magnetic field and an alternating electric field, with a frequency of f = 1   kHz . Using an RLC bridge, we measured the series electric capacitance, C s , and the tangent of the loss angle, D s . From the functions C s = C s (δ) C C s and D s = D s (δ) C C s , we extracted the components of the complex dielectric permittivity. It was found that the CIPs embedded in the MS matrix aggregated, leading to magneto-dielectric effects such as the enhancement of the complex dielectric permittivity components when applying the magnetic field as a principal effect and the enhancement of the electric capacitance and time constant of the capacitors as a secondary effect. The obtained results represent landmarks in the realization of low-cost magnetic field sensors, deformation and mechanical stress transducers in the robotics industry, etc. [ABSTRACT FROM AUTHOR]

This work consists in the process of preparing magnetic active composite materials based on cotton fibers, iron carbonyl microparticles and barium titanate nanoparticles, and the electrical devices manufactured with them. For different compositions of the aforementioned ingredients, three such composites are manufactured and compacted at constant pressure between two electrodes. In the absence and in the presence of a magnetic field, using an RLC bridge, magnetocapacitive, magnetoresistive and magnetopiezoelectric effects are highlighted in the custom fabricated devices. It is shown that these effects are significantly influenced by the composition of the materials. Based on the model elaborated in this paper, the mechanisms that contribute to the observed effects are described and the theoretical predictions are shown to agree with the experimental data. The obtained results can be used in the assembly of hybrid magnetic active composites, which are low cost, ecological and have other useful physical characteristics for applications. [ABSTRACT FROM AUTHOR]

The microwave absorbing and shielding properties of epoxy composites with multiphase filler were studied in a wide frequency range of electromagnetic radiation (EMR) (1–67) GHz. The multiphase filler consists of carbon nanotubes (CNTs) and dielectric (titanium dioxide TiO2) or ferromagnetic (carbonyl iron Fe) particles. The content of TiO2 or Fe was fixed and equal to 35 wt% and 30 wt%, respectively, while the CNT content was varied from 1 to 5 wt%. It was found that EMR shielding efficiency SET is sufficiently increased with carbon nanotubes content and thickness of the composite especially for epoxy CMs filled with carbon nanotubes and carbonyl iron. The measured complex permittivity data (and permeability for CNT/Fe/epoxy CMs) were used for simulation of the reflection loss RL for studied composites. The simulated data have shown that more pronounced reflection loss RL min = (30–44) dB is observed for 2–3 wt% CNT content in ternary epoxy CMs (sample thickness is 0.5–0.7 mm). For the higher CNT content (4–5 wt%), especially for CNT/Fe/epoxy CMs, the reflection loss RL min was decreased, i.e., the large contribution in EMR attenuation is provided due to EMR reflection on the first air-composite boundary. It was shown that effective bandwidth of RL min at level 10 dB can achieve (8–12) GHz and its position and RL min value can be manipulated by varying the composition and thickness of the composite sample. The absorbing performance of 4-layered composite structures was modeled using electromagnetic parameters of single-layer absorbers based on the three-phase composites and optimal layers composition and thickness were found. [ABSTRACT FROM AUTHOR]

This study investigates the influences of electric and magnetic fields applied both separately and superimposed on the dielectric and elastic properties of membranes (Ms) composed of cotton fabric and carbonyl iron microparticles (CI). To this end, three membranes were fabricated: one without CI microparticles and the remaining two with various proportions of CI microparticles. Additionally, scanning electron microscopy and energy emission X-ray spectroscopy were used to perform morphological and elemental analysis of the cotton fabric sample, CI microparticles, and the prepared Ms. Subsequently, flat capacitors (FCs) were manufactured using these Ms, encapsulated in a silicone rubber sheath. The FCs were introduced in static electric and magnetic fields superimposed over a sinusoidal electric field of frequency f = 1 kHz, and the electric capacity Cpand the tangent of dielectric loss angle Dpof the FCs were measured, depending on the E values of the static electric and magnetic fields superimposed over the medium-frequency electrical field. The values of the static electric field intensity and magnetic flux density were varied in steps of 4 kV/m within an interval 0 ≤ E (kV/m) ≤ 48 and in steps of 100 mT within an interval 0 ≤ B (mT) ≤ 300, respectively. Based on the obtained data, the components of the complex dielectric permittivity, those of the deformations, and the coefficients of elasticity of the Ms were determined to characterize the dependence of these values on the composition of Ms under the applied fields. Furthermore, the observed physical mechanisms were described based on the elements of physics of linear dielectrics and small deformation theory. Ultimately, the development of these materials can aid the design of various electrical devices for diverse applications such as sensors with electric field transducer, magnetic field, vibrations, and mechanical deformations.

In this work, we present the manufacturing process of magnetizable membranes based on cotton microfibers, honey, carbonyl iron, and three different concentrations of silver microparticles. Each membrane is used as a dielectric material for the fabrication of electrical devices. By using the plane capacitor method, the electrical capacitance and dielectric loss tangent are measured in a medium-frequency alternating field superimposed on a static magnetic field. From the obtained data, the time constants of the devices, the components of complex dielectric permittivity, and the electrical conductivity of the membranes as a function of the electric field frequency and magnetic flux density can be extracted. The results show that the obtained membranes can be useful for the fabrication of low-cost and environmentally friendly magneto-active membranes that are required for various technical and biomedical applications.

The finishing accuracy and efficiency of magnetic abrasive finishing (MAF) are mainly depending on magnetic abrasive powders (MAPs). A new kind of core–shell structured carbonyl iron powders (CI-MAPs) with a hard Fe/Al intermetallic shell for magnetic abrasive finishing is successfully synthesized by in-situ alloy-hardening the surface of spherical carbonyl iron powders in this study. The feasibility of such an in-situ alloy-hardening strategy is theoretically designed according to the Fe/Al intermetallic compound formation chemical reaction using the Gibbs free energy principle and the TG-DSC testing, and thus the experimental thermodynamics temperature and time ranges of such chemical reactions are proposed. Experimental results shown that a densely zigzag-like uniform alloy-hardening layer with a thickness of about 11 μm, which are composed of Fe3Al, FeAl, and Fe2Al5 intermetallic compounds, was in-situ chemically synthesized on the surface of the spherical carbonyl Fe powders. The achieved core–shell structured powder is performed to finishing a Zirconium tube experimentally, and the roughness (Ra) of the Zirconium tube is greatly improved from 0.361 μm to 0.085 μm by 3 MAF passes.

In order to realize wide-band, high-efficiency and flexible electromagnetic wave absorption, an effective method is the combination of different electromagnetic functional materials. How to use and make the multilayer materials with individual absorption, reflection and selective transmission characteristics is very important. In this work, multilayer composite flexible absorbing fabrics made of a frequency selective surface (FSS), carbonyl iron coated fabrics (CIFs) and copper-nickel plated conductive woven fabrics (CWFs) were prepared. The layered composite materials have a thin thickness, good flexibility and adjustable absorption band, which provide a reference for the development of lightweight and efficient electromagnetic wave absorbing materials. The influence of the resonance point, wave absorbent content and conductive layer on the absorbing properties were studied. CIF-3 with a surface density of 2046.9 g/m2 has the best absorption performance with a minimum reflectivity of –20.52 dB at 12.56 GHz. A one-layer FSS can broaden the absorption bandwidth; the broadening degree varies with the resonance point of the FSS, which also makes the absorption band adjustable. The bandwidth of f12/CIF-3 with reflectivity of less than –10 dB can reach 5.68 GHz. Besides, CWF is beneficial to increase the absorption intensity, and the best reflectivity of CIF-3/CWF can reach –27.73 dB. Furthermore, three-layer composites can improve the absorption strength and bandwidth of CIF at low frequency. Compared with CIF-3, the reflectivity of f14/CIF-3/CWF decreases 8.06 dB at 11.28 GHz, and the bandwidth is 4.72 GHz, which widens by 0.32 GHz. [ABSTRACT FROM AUTHOR]

Self-healing magnetic polyurethanes have been fabricated with 4,4′-methylene diphenyl diisocyanate (MDI), poly(1,4-butylene adipate) (PBA-2000), furfurylamine (FMA), bismaleimide (BMI), and magnetic materials (magnetite, carbonyl iron, and magnetite-coated carbonyl iron which was prepared by a vortex mixer in a solid-state process). The magnetic polyurethanes have three properties of self-healing, thermal radiation shielding, and reducing the temperature of the retro Diels–Alder reaction. The magnetic polyurethanes showed the self-healing performance of a notch at 110 °C in a short time, the self-healing recovery was 82.1% in the breaking strength after the healing process, and the excellent thermal radiation shielding. The polyurethanes were investigated by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscope (TEM), optical microscope (OM), ultraviolet–visible (UV–Vis) spectroscopy, tensile testing, and thermal conductivity. Finally, the self-healing magnetic polyurethanes which with the properties can be promising materials for the building or the constructing applications in the future. [ABSTRACT FROM AUTHOR]

Carbon-based/carbonyl iron composite microwave absorption materials have become a hot topic in recent years because of the combination of their respective advantages and unique physical and chemical characteristic and good absorbing properties. In this paper, the most recent and important research advances in carbon-based/carbonyl iron composite microwave absorption materials were reviewed. Firstly, the recent research of property improving of carbonyl iron itself was introduced. Then, the research achievements of carbon-based/carbonyl iron composite microwave absorption materials were summarized in six major categories, graphene/carbonyl iron microwave absorption materials, carbon nanotubes/carbonyl iron microwave absorption materials, carbon fibre/carbonyl iron microwave absorption materials, carbon black/carbonyl iron microwave absorption materials, graphite/carbonyl iron microwave absorption materials and the other composites were reviewed in detail. Finally, the performance control and lightweight of carbon-based/carbonyl iron composite microwave absorption materials were pointed out, and its development prospect in broadband stealth was prospected.

In this paper, we present the procedure for fabricating a new magneto-tactile sensor (MTS) based on a low-cost commercial polyurethane sponge, including the experimental test configuration, the experimental process, and a description of the mechanisms that lead to obtaining the MTS and its characteristics. It is shown that by using a polyurethane sponge, microparticles of carbonyl iron, ethanol, and copper foil with electroconductive adhesive, we can obtain a high-performance and low-cost MTS. With the experimental assembly described in this paper, the variation in time of the electrical capacity of the MTS was measured in the presence of a deforming force field, a magnetic field, and a magnetic field superimposed over a deformation field. It is shown that, by using an external magnetic field, the sensitivity of the MTS can be increased. Using the magnetic dipole model and linear elasticity approximation, the qualitative mechanisms leading to the reported results are described in detail.

Hard-magnetic barium ferrite (BF) nanoparticles with a hexagonal plate-like structure were used as an additive to a carbonyl iron (CI) microparticle-based magnetorheological (MR) fluid. The morphology of the pristine CI and CI/BF mixture particles was examined by scanning electron microscopy. The saturation magnetization and coercivity values of each particle were measured in the powder state by vibrating sample magnetometry. The MR characteristics of the CI/BF MR fluid measured using a rotation rheometer under a range of magnetic field strengths were compared with those of the CI-based MR fluid. The flow behavior of both MR fluids was fitted using a Herschel–Bulkley model, and their stress relaxation phenomenon was examined using the Schwarzl equation. The MR fluid with the BF additive showed higher dynamic and elastic yield stresses than the MR fluid without the BF additive as the magnetic field strength increased. Furthermore, the BF nanoparticles embedded in the space between the CI microparticles improved the dispersion stability and the MR performance of the MR fluid.

Particle oxidation constitutes a serious ageing phenomenon in magnetorheological suspensions, bringing about deterioration in performance. This study describes commercial carbonyl iron particles that were successfully coated with poly(amidoamine) dendrons and then applied as an oxidation-resistant dispersed phase in magnetorheological suspensions. A synthesis method was adhered to whereby the particles were sequentially treated with ethylenediamine and methyl acrylate, leading to the formation of generation 2 and 2.5 dendrons; these had the capacity for composite particles with a nano-scale dendritic layer to be prepared on their surfaces. Success in applying the coating was confirmed by various techniques, including XPS, TEM, EDX, FTIR and Raman spectroscopy. The controlled approach adopted to coating the carbonyl iron particles resulted in them exhibiting sufficient oxidation stability, with only an ~ 4.5–4.7% decrease in saturation magnetization. Of interest was that their magnetorheological suspensions demonstrated ca 4.8% and 4% higher dynamic yield stress than a suspension based on non-modified particles at the highest intensity of magnetic field investigated, i.e. 438 kA m–1. Notably, sedimentation stability was evaluated by a unique method that involved the use of a tensiometer with a specific testing probe. The aforementioned coating process led to enhanced sedimentation stability of the magnetorheological suspensions based on coated particles possibly due to decrease in the overall density of the particles, enhanced dispersion stability and reduction in the size of their agglomerates in the silicone oil mixtures that were confirmed by optical microscopy. Modification of the particles as proposed has the potential to overcome one of the primary drawbacks of magnetorheological suspensions, this being oxidation instability (which leads to what is referred to as "in-use-thickening"), without negatively affecting their performance in the presence of a magnetic field. [ABSTRACT FROM AUTHOR]

The electrical and thermal conductivity of the ternary epoxy composites (CMs) with two-component fillers, multiwall carbon nanotubes (MWCNT)/TiO2, and MWCNT/carbonyl iron (Fe) have been investigated. The increase of the percolation threshold was found for the ternary CMs compared to MWCNT/epoxy CMs. At MWCNT content higher than 3 wt.%, the conductivity of the ternary CMs is much higher than in MWCNT/epoxy. The temperature dependencies of the electrical resistivity were analyzed within the fluctuation-induced tunneling conductivity model. It was found that adding of two-component fillers MWCNT/TiO2 or MWCNT/Fe into epoxy promotes smaller changes in thermal conductivity compared to the two-phase MWCNT/epoxy composites. [ABSTRACT FROM AUTHOR]

Fe-powder and paraffin-based or similar systems are widely used for low-temperature injection molding. The main attention of research efforts on such compositions is focused on the study of their rheology. At the same time, such materials can be adapted for 3D printing by layer-by-layer surfacing, requiring only necessary rods or filaments with a sufficient level of mechanical properties so as not to break during printing. Hence, this paper examines the influence of paraffin content on the compressive strength of samples made of carbonyl iron powder and paraffin in the ratio: 50/50, 60/40, 70/30, and 80/20 vol.%. Computer calculations of critical deformation, elasticity modulus, and compressive strength of such composites have been performed. According to the examination and calculation results, the modulus of elasticity varies from 1358 to 113 MPa with a higher paraffin content, the critical deformation ranges between 0.257 and 3.310, and the compressive strength is between 0.339 and 0.761 MPa. Iron powder was mixed with paraffin in a planetary mill for 3 min with a subsequent sieving of the mixture. Afterward, pressed cylindrical samples with a volume of ~1 cm3 and a height of ~10 mm were used to determine the density and compressive strength. It was found that the density of the samples after pressing is 1.3 times lower than the calculated by the additivity formula at a binder content of 20 vol.%. Only when the binder content increases to 50 vol.%, the actual density approaches the calculated values, that is, the relative porosity varies from 0.212 to 0. With an increase in paraffin content from 20 to 50 vol.% the strength of the samples increases along the concave curve from 3 to 11 MPa. The dependences of the calculated and experimentally obtained compressive strength are similar, indicating the adequacy of the established models. However, significant variation in values is due to the difference between the properties of paraffin under study and that used for testing. Samples of rods with 40 and 60 vol.% Fe was extruded and tested by 3D printing. The obtained experimental data can be used in the creation of other similar working materials for 3D printing in the layer-by-layer surfacing. [ABSTRACT FROM AUTHOR]