Non-oriented Samples Research Articles

Effect of Ga substitution on grain orientation and magnetostrictive properties of polycrystalline CoFe2O4 ceramics prepared by the solid-state method

As a kind of magnetostrictive ceramics, cobalt ferrites are widely concerned because of its large magnetostriction and high resistivity, which are ideal for high-frequency applications. But, the high driving magnetic field due to the high magnetocrystalline anisotropy limits the practical applications of cobalt ferrites, thus, it is a still a challenge to find a balance between high magnetostriction properties and low driving magnetic fields. In this work, we investigated the effects of partially substitution of Ga3+ for Fe3+ on grain orientation and magnetic properties, attempting to maintain high magnetostriction while reducing the driving magnetic field. The CoFe2-xGaxO4 (x=0, 0.05, 0.1, 0.15) with single-phase spinel structure were prepared by the conventional solid-state method. The saturation magnetization MS increased with the increase of Ga concentration, meanwhile the coercivity Hc and magnetocrystalline anisotropy constant K1 significantly decreased, which indicates the better soft magnetic characteristics of the Ga-doped cobalt ferrites. The oriented CoFe2-xGaxO4 samples were obtained using magnetic field orientation technique during the powder forming process. The <001> preferred orientation was achieved in CoFe2O4 samples. However, the <001> orientation degree decreased with the substitution of Ga, and the preferred orientation has changed into <111> at x=0.15. The Ga substitution affected the magnetocrystalline anisotropy and grain orientation, thereby affecting the magnetostrictive properties. As for the non-oriented samples, although the maximum magnetostrictive strain slightly decreased with Ga substitution, while there was a significant drop in the magnetostrictive saturation field. However, the magnetostriction of the oriented samples decreased significantly with the substitution of Ga due to the change of grain orientation from <001> to <111>.

Analyzing the impact of interlocking on non-oriented electrical steel (NOES) laminations: A microstructural and mechanical property perspective

Non-oriented electrical steel laminations are widely used in electric motor cores and are manufactured using various techniques such as cutting, punching, interlocking, and welding. These manufacturing processes can have a detrimental effect on the performance of the electric motor. Thus, in order to enhance the performance of the electric motor, it is essential to comprehend the microstructural, mechanical, and magnetic property changes resulting from manufacturing. The current study focuses on the microstructural modifications caused by interlocking, which is known to impact the core magnetic properties of motors, and its relation to mechanical properties like hardness. Six interlocked non-oriented electrical steel samples were prepared by incomplete punching at different loads from 500 N to 4000 N. Scanning Electron Microscopy (SEM) and Electron backscattered diffraction (EBSD) analysis was performed on the interlocked samples to study the microstructure and crystallographic texture near the edge whereas nanoindentation was used to determine the hardness profile. Pop-in analysis was done to study the extent of work hardening due to punching and its effect on hardness. The hardness change due to residual stress was determined, which was used to estimate the induced residual stress near the edge. It ranged from 0.04 GPa at 550 N load to 11 GPa at 4000 N load near the punched edge.

Systematic orientation of fresh rectal suction biopsies improves histopathological diagnostics in hirschsprung’s disease – a method description and preliminary report

BackgroundOptimizing rectal suction biopsy (RSB) diagnostics in Hirschsprung’s disease (HD) may shorten diagnostic time and prevent need for repeated biopsies.AimTo explore whether systematic orientation of fresh RSB specimens increased biopsy quality, diagnostic times, diagnostic efficacy, and histopathologic workload, and to explore these outcome measures for aganglionic specimens.Materials/MethodsThis was an observational case-control study conducted at a national referral center for HD on data collected from the local HD-diagnostic register. From 2019 each fresh RSB was oriented by the collector in a notch in a foam cushion, placed in a separate cassette, and sent in formalin for pathological analysis. Outcome measures of oriented RSB samples collected 2019–2021 were compared to those of non-oriented RSB samples collected 2015–2018. Staining/immunohistochemistry consisted of hematoxylin eosin, S-100 and calretinin.Results78 children with 81 RSBs and 242 biopsy analyzes were included. The frequency of high-quality RSB specimens was higher in oriented: 40% (42/106) versus non-oriented 25% (34/136) (p = 0.018), the diagnostic turnaround time was shorter: 2 days (1–5) versus 3 days (2–8) (p = 0.015), and the number of additional sectioning/leveling/re-orientation per biopsy was lower: 7 (3–26) versus 16 (7–72) (p = 0.011). Specifically for aganglionic specimens, the frequency of high-quality biopsies was generally higher in oriented than in non-oriented RSB specimens: 47% (28/59) versus 14% (7/50) (p < 0.001); the diagnostic efficacy was higher 95% (19/20) versus 60% (9/15) (p = 0.027) and the diagnostic turnaround time shorter: 2 days (2–3) versus 3 days (2–8) (p = 0.036).ConclusionsSystematic orientation of fresh RSB specimens improves HD diagnostics. Improvement was consistent in aganglionic specimens.

Improved room-temperature magnetoelectric effect and crystal structure in polycrystalline BaSrCo2Fe11AlO22

The crystal structure and the magnetoelectric (ME) effect were investigated in highly c-axis oriented polycrystalline samples of Y-type hexaferrite, BaSrCo2Fe11AlO22, fabricated using a rotating magnetic field. A detailed crystal structure was determined using a combination of scanning transmission electron microscopy and single crystal x-ray diffraction. It was revealed that Co and Al ions, which play important roles in the performance of the ME effect, reside mainly on the Fe site in the S block of the Y-type hexaferrite. In the oriented samples, electric polarization induced by applying a magnetic field reached 140 μC/m2 at 200 K and 51 μC/m2 at 300 K; consequently, the ME coefficient αH was estimated to be 7200 ps/m at 300 K. The ME performance of the oriented samples is superior to that of nonoriented polycrystalline samples and comparable with that of single crystals. Furthermore, the oriented samples allow the control of magnetization by an electric field up to 325 K. These results facilitate further investigations on room-temperature multiferroics and their practical applications.

Magnetic properties measurement and analysis of electrical steel sheet under cutting influence

The cutting process of silicon steels is a necessary manufacturing technique in electrical equipment. Different cutting methods have different effects on the internal structure and magnetic properties of the electrical steel sheets. Laser cutting can produce thermal stress during processing, while mechanical cutting may cause plastic deformation near the cutting edge, which both lead to deterioration in the magnetic properties of the material. Therefore, studying the effect of different cutting techniques on magnetic properties is of great significance to accurately predict the iron losses of electrical equipment. In this paper, a mobile B-H sensing structure is designed to sense the distribution of local magnetic properties near the cutting edges. Magnetic properties of the non-oriented (NO) silicon steel samples B35A270 and 50JN470 are measured and characterized with the variation of distance from cutting edges. The results demonstrate that the deterioration of magnetic properties depends on the cutting methods and the material characteristics. Wire cutting has little effect on magnetic performance and the effect can be observed near the cutting edge. As a contrast, the decrease of the relative magnetic permeability can be observed in a deeper width of the steel strips cutting by laser. Moreover, the multiple trends of laser cutting loss which vary with cutting depth are compared and discussed. This research can provide a reference for the application of electrical equipment under actual working conditions.

The influence of residual stress on flux-barriers of non-oriented electrical steel

In rotating electrical machines, cutouts in the rotor laminations control the magnetic flux density distribution in the d- and q-axis of the magnetic core. Guiding the magnetic flux by cutouts leads to very narrow bridges in the electrical steel. However, at the same time, this can limit the maximum speed of a rotor e.g. due to the material’s maximum allowed mechanical stress. Therefore, the centrifugal forces confine the achievable power density. The aim of this study is the examination of the effect of flux-barriers fabricated by mechanical embossing on the magnetic properties of non-oriented electrical steel. The embossing process causes a static residual stress distribution and thereby a reduction of the permeability resulting from Villari’s effect. The non-oriented electrical steel samples are embossed with varying distances between the barriers and measured at different angles to the barrier edges on a single-sheet tester. A comparison with respect to their directional and embossing geometry-dependent effectiveness as magnetic flux barriers is carried out. A correlation of the results with measurements of the local flux density, obtained by neutron-grating interferometry, is performed in order to enable a consideration of the mechanical embossing on the local magnetic flux density distribution.

Design and fabrication of Fe–Si–Al soft magnetic composites by controlling orientation of particles in a magnetic field: anisotropy of structures, electrical and magnetic properties

Soft magnetic composites (SMCs) have rapidly become the hot spots of research, because of competitive magnetic saturation and high electrical resistivity. Although the magnetic properties have been continuously improved, the nonmagnetic separation and high demagnetization in structure result in low permeability. In this study, Fe–Si–Al SMCs with various particle orientations are designed and prepared under magnetic field. The effects of structures with various orientations on hysteresis loops, effective permeability, magnetic loss and electrical resistance are studied. The results show that the electrical and magnetic properties are totally determined by particle orientation. Especially, compared with non-oriented samples, the permeability of fully oriented samples with particles perpendicular to the normal axis has been greatly improved. This work is of great significance for the research and application of SMCs.

Feasibility of applying viscous remanent magnetization (VRM) orientation in the study of palaeowind direction by loess magnetic fabric

AbstractThe loess formation sampling method on the Chinese Loess Plateau generally involves the acquisition of samples from the basset section and the drilling core. Constraints imposed by the precision of the drilling machine operation make it difficult to determine the orientation of the samples due to the rotation of the core.Although researchers have proposed solutions for reconstructing the north direction of the samples by adopting the viscous remanent magnetization (VRM) orientation, it remains uncertain whether this approach can be adopted in studies that use the magnetic fabric to trace the palaeomonsoonal direction, and the degree to which this approach will change the magnetic fabric results.Based on the achievements of other researchers, we adopted the VRM orientation of the basset section samples oriented in the field. By determining how the VRM orientation changes the magnetic fabric of loess over different demagnetization temperature ranges, we can draw the preliminary conclusion that there is no significant difference between the magnetic fabric information of the loess obtained at 100–150°C VRM orientation and that obtained from the field orientation (the statistical bin size is 22.5°, significance level α = 0.05). This indicates that the VRM orientation approach is feasible for studying non-oriented drilling core samples to determine the prevailing surface paleowind direction with appropriate precision.

(Invited) Proton Conductivity Enhancement in Polymer Thin Films By Molecular Orientation and Organized Structure

Highly proton-conductive polymers have long attracted the attention of researchers for use in energy conversion, sensors, catalysts, and other applications. From the viewpoint of scientific history of creating highly proton-conductive polymers, one fundamental approach is based on the strategy of phase-segregated structures with strong acid groups.[1-3] Protons are considered to be transported through the hydrophilic parts. In the recent polymer research fields, taking advantage of the interface extends the molecular design such as the oriented structure and organized structure for the highly proton conductive materials. Matsui et al. showed anisotropic proton conductivity in Langmuir–Blodgett thin films with well-defined lamellar structures [4]. Proton conductivity is enhanced by the formation of 2D hydrogen-bonding networks in multilayer nanosheets [5, 6]. In this presentation, the author demonstrates a new approach to enhance the proton conductivity of the polymer thin films using an interface that can modify the degrees of freedom for a polymer structure through interaction between the substrate surface and polymers.[7-12] The interface can modify the degrees of freedom for polymer structures through interaction for functional groups, wettability, and surface charge between the substrate surface and polymers. Some proton-conductive polymers exhibit an oriented structure determined by an IR p-polarized multiple angle incidence resolution spectrometry (pMAIRS) [13]. Their oriented thin films show unique proton transport properties compared to those of non-oriented samples.

Estimation of the Deformation Value in Terrigenous Rocks by the Random Cross-Section Method (Belaya River, Northern Slope of the Greater Caucasus)

The deformation value in the Lower and Middle Jurassic terrigenous rocks from the valley of the Belaya River (the northern slope of the Greater Caucasus) is quantified by the morpholology of the cleavage zones. The numeral determination of the axis ratios of the deformation ellipses by the Fry method is performed as well. It is shown that for a statistical sample of the random cross-sections of the thin sections in the terrigenous rocks with cleavage structure the deformation value can be estimated correctly. The method of random cross-sections described in this work can be used for the quantitative estimation of deformation in nonoriented samples of terrigenous rocks.

Microstructural Magnetic Characterization of Annealed Non-Oriented Electrical Steel

The present paper investigates the utilization of the magnetic Barkhausen noise and magnetic permeability methods for the nondestructive characterization of annealed non-oriented electrical steel samples which were isothermally annealed in a wide range of temperatures (400°C – 950°C) and subsequently cooled in air. The resulting magnetic properties were compared with the microstructural changes occurring during annealing.

Preparation and evaluation of magnetic field-induced orientation on magnetic nanoparticles on PVA nanocomposite films

Magnetite Fe3O4 particles (M) were dispersed in polyvinyl alcohol (PVA) and oriented successfully by applying low external magnetic field. Observed orientation was verified by image analysis using ImageJ software. Crystallinity of the M/PVA samples was examined using DSC, showing a lower crystallinity by addition of particles and higher crystallinity resulting from orientation. Orientation of 0.05 and 0.1 wt% of M particles increased crystallinity of nanocomposites 39 and 57%, respectively. Tensile tests were also measured to examine the mechanical properties of oriented and non-oriented samples. Results show that the mechanical properties of samples including elongation at break and modulus had improved in the direction of oriented particles. Afterward, graphene oxide particles were magnetized [magnetic graphene oxide (MGO)] and dispersed in PVA resulting in improved mechanical properties. PVA/MGO nanocomposites showed better mechanical properties than PVA/M, although no improvement in the crystallinity was observed.

Effect of precipitates on grain growth in non-oriented silicon steel

Abstract

Effect of Cross-Rolling on Microstructure, Texture and Magnetic Properties of Non-Oriented Electrical Steels

Hot rolled non-oriented electrical steel samples were subjected to cold cross-rolling of 80 % reduction in thickness. The cross-rolled samples were then annealed at 650, 750 and 850 oC for 1 hr, 2 hrs and 4 hrs respectively. The role of cross-rolling on microstructure, texture and magnetic properties of the samples after annealing has been investigated. Two different samples were used for the present investigation - one had higher Al content (sample S1) while the other had higher C, Si, Mn, P and S content (sample S2). It was observed that the sample S1 had higher grain size compared to sample S2 after annealing. The cross-rolling was observed to be controlled the texture developments in the samples and it was found that the texture factor was identical in all directions of the sample. The core losses in the samples were found to be decreased with increasing grain size of the samples.

Magnetic Barkhausen Measurements for Determining Residual Stress Distribution in Welded Electrical Steels

In the present research work the determination of residual stress distribution in welded non-oriented electrical steel samples is discussed. Tungsten Inert Gas and Electron Beam Welding were used as the welding methods. The residual stresses induced by welding estimated by the magnetic, non-destructive method of Barkhausen noise and were compared with the values resulting from the semi-destructive method of X-ray diffraction Bragg-Brentano (XRD-BB). In order to evaluate accuracy and reliability of the magnetic methods applied, the steel samples were subjected in both compressive and tensile stress and the magnetic noise values were correlated to residual stress values through an appropriate calibration curve. Furthermore, the fluctuations of the residual stresses in the welding zones of the welded samples were discussed on the basis of the experimental evidence and the microstructural changes occurring during welding. It was found that the residual stress determined by MBN method was in good agreement with the XRD-BB results. However, the residual stress determined by magnetic permeability method was not in good agreement with the XRD-BB results. In contrast to the XRD-BB method, the magnetic techniques required a precise calibration procedure in all zones with noticeably different microstructure.

An accurate evaluation of the residual stress of welded electrical steels with magnetic Barkhausen noise

In the present research work the determination of residual stress distribution in welded non-oriented electrical steel samples is discussed. Tungsten Inert Gas, Plasma and Electron Beam were used as the welding methods. Residual stress was directly determined through deformation measurements and appropriate math calculations. Two methods were used: The magnetic, non-destructive method of Barkhausen noise and the semi-destructive method of X-ray diffraction. In order to evaluate accuracy and reliability of the magnetic method applied, the steel samples were subjected in both compressive and tensile stresses and the magnetic noise values were correlated to residual stress values through an appropriate calibration curve. The results were then verified by the XRD method. Then, these were further evaluated by examining the microstructure and mechanical properties of as received and welded samples by scanning electron microscopy and macrohardness measurements, respectively. It was found that the deviation between the two methods was within acceptable limits, thus implying potential applicability of the MBN method in non-destructive testing of materials.

A novel approach of accurately evaluating residual stress and microstructure of welded electrical steels

In the present research work the determination of residual stress distribution in welded non-oriented electrical steel samples is discussed. Tungsten inert gas was used for the welding method. Residual stress was directly determined through deformation measurements and appropriate math calculations. Two methods were used: the magnetic, non-destructive method of Barkhausen noise and the semi-destructive method of X-ray diffraction. In order to evaluate the accuracy and reliability of the magnetic method applied, the steel samples were subjected to both compressive and tensile stresses and the magnetic noise values were correlated to residual stress values through an appropriate calibration curve. The results were then verified by the XRD method and were further evaluated by examining the microstructure and the mechanical properties of the as received and welded samples through scanning electron microscopy and hardness measurements, respectively. It was found that the deviation between the two methods was within acceptable limits, thus implying potential applicability of the MBN method in non-destructive testing of materials.

Phase behaviors of binary mixtures composed of banana-shaped and calamitic mesogens

In this work, five mixtures with different concentrations of banana-shaped and calamitic compounds have been prepared and subsequently studied by polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction on non-oriented samples. The phase sequences and molecular parameters of the binary systems are presented.

Stress evaluation in non-oriented electrical steel samples by observation of vector magnetic flux under static and rotating field conditions

Stress evaluation in non-oriented electrical steel samples by observation of vector magnetic flux under static and rotating field conditions

Chiral Discotic Mesophases from Peralkanoylated Saccharides. Penta-O-n-Decanoylglucopyranose

The synthesis and preliminary characterization of new discotic-forming molecules prepared by peralkanoylation of saccharides is described. In particular, the mesomorphic properties of α- and β-anomers of penta-O- n-decanoyl glucopyranose have been confirmed by microscopy, liquid crystal induced circular dichroism, and X-ray diffraction of non-oriented samples. A non- hexagonal columnar ordering is proposed.