Search results for "Microstructure"
showing 10 items of 707 documents
Microstructure of freestanding single-crystalline Ni2MnGa thin films
2011
Abstract The complex crystal structure and variant distribution of single-crystalline freestanding Ni–Mn–Ga films was studied in detail using X-ray diffraction in two- and four-circle geometry. Selective chemical etching of a chromium buffer layer facilitates the release of the rigid MgO substrate that would inhibit magnetically induced reorientation (MIR) of variants. The substrate-constrained as well as the freestanding films possess identical crystal structure featuring a seven-layered (pseudo-)orthorhombic modulation (7 M/14 M). Of the 12 different variants observed before and after releasing the film from the substrate, four are predominantly represented. These have the short c -axis a…
Tetrahydrofuran: More than a “Randomizer” in the Living Anionic Copolymerization of Styrene and Isoprene: Kinetics, Microstructures, Morphologies, an…
2020
The statistical anionic copolymerization of isoprene (I) and styrene (S) is commonly used to synthesize tapered block copolymers, enabling control of the phase behavior by adjusting the order–disor...
Structure and thermal properties of a chitosan coated polyethylene bilayer film
2012
The thermal and the structural properties of chitosan coated polyethylene (PE) films were studied. The coating process did not significantly influence the thermal stability and the PE surface structure and/or composition of the polyolefin. Dehydration temperature of chitosan films reflected the strength of water/acetic acid/chitosan chains interactions. Glycerol, used as a plasticizer, formed new hydrophilic centres in the film matrix. Moreover it was better integrated in the CSEGLY than in CSAGLY network. Besides, the addition of a plasticizer in the chitosan films decreased the film degradation temperature. There were two main steps for the PE chitosan coated films degradation. The first …
INFLUENCE OF MONOXIDES ADDITION ON SINTERING OF SODIUM-POTASSIUM NIOBATES SOLID SOLUTION
2008
ABSTRACT In this paper the preparation, structure and dielectric parameters of ceramics from different powders of pure potassium sodium niobate (KNN) and KNN doped with 1.0 wt% of Li2O, CdO, Bi2O3, MnO2, V2O5 and WO3 have been studied. The dopping of sintering aids did not affect the crystallographic structure of the ceramics significantly; all ceramic samples had a single-phase perovskite structure. Added elements Li2O, CdO, MnO2, V2O5 effectively decreased the sintering temperature of KNN (50°–80°C). All sintering aids influenced sinterability, microstructure and dielectric properties of ceramics. Dielectric constant for doped samples increased from 6000 up to 8000.
Microstructure and mechanical properties of plasma spraying coatings from YSZ feedstocks comprising nano-and submicron-sized particles
2015
Atmospheric plasma spraying (APS) is an attractive technique to obtain nanostructured coatings due to its versatility, simplicity and relatively low cost. However, nanoparticles cannot be fed into the plasma using conventional feeding systems, due to their low mass and poor flowability, and must be adequately reconstituted into sprayable micrometric agglomerates. In this work, nanostructured and submicron/nanostiuctured powders of yttria-stabilised zirconia (YSZ) were deposited using APS, with a view to obtaining high-performance thermal bather coatings (IBC). All powders were reconstituted by spray-drying from different solid loading suspensions, followed by a thermal treatment of the spra…
The effect of less additives on magnetic properties and microstructure of sintered Nd–(Fe,Ti,Al)–B magnets
2001
Abstract The effect of the addition of 0.5 at.% Cu, Ga, Hf, V, Mo, Nb, Co, Ni, Cr, Dy or Tb on the magnetic properties and the microstructure of sintered Nd 16 Fe 75.22 Ti 1.26 Al 0.32 B 7.2 magnets has been studied. It is shown that these additives cause a small decrease in remanence and in intrinsic coercivity, with the exception of Cu, Dy and Tb additives, which lead to an increase in the intrinsic coercivity. The correlation between the hyperfine magnetic field and the magnetic properties of the investigated magnets is discussed.
Preparation of magnetic composites of MIL-53(Fe) or MIL-100(Fe) via partial transformation of their framework into γ-Fe2O3
2016
A novel two-step approach is proposed to obtain magnetically active composite materials consisting of MIL-53(Fe) or MIL-100(Fe) and γ-Fe2O3 particles. The first step consists in a partial transformation of the framework into a layer of γ-FeO(OH) (lepidocrocite) covering the MOF particles. We found that such a transformation can be realized under air-free conditions by hydrolysing the MOFs at pH 6.2 in the presence of FeSO4. In the second step the obtained γ-FeO(OH)/MOF composite is heated under an air flow at 250 °C in order to transform γ-FeO(OH) to γ-Fe2O3. The thus prepared composites containing 40 wt% of the magnetic phase were characterized in detail by XRD, HRTEM, FESEM, N2 adsorption…
Enhanced thermoelectric properties of the n-type Magnéli phase WO2.90: reduced thermal conductivity through microstructure engineering
2014
The thermoelectric properties of the Magneli phase WO2.90 were investigated, with special attention to how the thermoelectric performance can be altered by changing its microstructure. Spark plasma sintering (SPS) allowed the direct preparation of large amounts of consolidated material. Adding Ta2O5 to the reaction mixture lead to the formation of solid solutions W1−xTaxO2.90via a concurrent reaction between WO3 and Ta2O5 during the SPS treatment. In addition, micron-sized inclusions containing tungsten surrounded by WOx embedded in a WO2.90 matrix were formed, which act as additional scattering centers. As a result, the thermal conductivity of the Ta-containing samples was reduced by ≈30% …
Dielectric relaxation and polaronic hopping in Mn-substituted LaSrNiO4 nickelates prepared by mechanical milling method
2016
Abstract The structures, microstructures and dielectric properties of LaSrNi1−xMnxO4 (x = 0, 0.1, 0.2, 0.3 and 0.5) ceramics synthetized by mechanical milling followed by heat treatment were studied. One single tetragonal phase was revealed in all compounds. Structural parameters were obtained by Rietveld refinement. The substitution of Ni ions by Mn produces a variation of the lattice parameters but no phase change is observed. The surface morphology and elemental analysis of these samples were respectively investigated by Scanning Electron Microscopy (SEM) and energy dispersive X-ray technique (EDS). Giant dielectric response was observed in these ceramics, and at least two relaxations we…
Surface and interface analysis of worn TiN (PVD) coated cold forging tools
1992
Abstract Wear of cold forging tools, improved by TiN (PVD) hard coating and used in the production of alternator and starter components in the car industry, has been studied in detail. The most complicated case was the tool that produced a clutch housing of high precision. The 630 kN press process (50 pcs min −1 ) caused heavy adhesive and abrasive wear due to material flow, high surface pressure and also wear in the direction of tool movement. Results show that on the worn functional surfaces of the analysed tool, the lifetime of which was extended with TiN coating by a factor of 8–10, the following features were observed: non-uniform TiN coating thickness decrease; long grooves, damaged a…