Formation Of Phase Structure Research Articles

The Study of Structure Formation Evolution at High Pressure with a Shear in a Corrosion-Resistant Austenitic-Ferritic Steel 03Kh14N10K5M2YuT with Different Initial States

The article presents results of studies of phase transformations and structure formation that form the necessary complex of physical and mechanical properties of austenitic-ferritic steel with a structural ratio of 50:50. The structure formation at high pressure with a shear of steel 03Kh14N10K5M2YuT with different initial states is studied. After the action of intense plastic deformations, a submicrocrystalline structure arises. This causes interest in these deformations.

Improvement of the Turbine Blade Surface Phase Structure Recovered by Plasma Spraying

This paper presents the results of research on the construction, technological parameters and criteria that control the process of formation of optimal phase structure of austenitic- and martensitic-class material for steam turbine blades. The hypothesis that the established correlation could increase the quality of blade recovery and its resistance against dynamic and vibrational loads was proved. The efficiency of the developed implantation method for the recovery of steam turbine blades was demonstrated. The optimal technological parameters of the process of laser plasma recovery were established empirically, allowing the development of the system for the fine tuning of the phase composition of austenitic- and martensitic-class steel.

Annealing effect for self-assembled monolayers formed from terphenylethanethiol on Au(111)

The structure and morphology of self-assembled monolayers (SAMs) prepared on Au(111) from solutions of terphenylethanethiol (TP2) at room temperature and subsequently annealed at temperatures up to 473 K were investigated using scanning tunneling microscopy. This system is of particular interest because of its metastable character, holding potential for its tailored modification. Indeed, the data suggest the formation of several different structural phases, viz. α, β, γ, and δ, appearing progressively for the as-prepared and annealed samples. The consecutive α → β → γ → δ phase transitions occurring with increasing annealing temperature involved a continuous reduction of the molecular packing density and significant changes in the substrate morphology. The major morphological changes were the appearance and progressive growth of monoatomic gold islands, on top of which the TP2 phases were formed, representing in all cases a single domain for a particular island and restricted only by the island size. For all the phases, inclined molecular orientation was assumed while a so-called lying-down arrangement, in which the TP2 backbones are orientated parallel to the gold surface, was not observed. A nearly complete desorption of the TP2 molecules was recorded at an annealing temperature of 473 K, accompanied by the drastic change in the surface morphology.

Amorphous behavior of ZrxFeNiSi0.4B0.6 high entropy alloys synthesized by mechanical alloying

The effect of Zr addition with different proportions on the microstructure and thermal stability of mechanical alloying ZrxFeNiSi0.4B0.6 (x = 1, 1.5, 2.5) high entropy alloy powders have been investigated. The amorphous phase has been successfully manufactured by mechanical alloying. The results indicate that increasing Zr ratio can evidently shorten the time of complete amorphous phase formation, which enhance the amorphous forming ability. The ZrFeNiSi0.4B0.6, Zr1.5FeNiSi0.4B0.6 high entropy alloy powders are partially amorphous but still retain stable FCC solid solution structure. However, the Zr2.5FeNiSi0.4B0.6 pseudo high entropy alloy powders obtain full amorphous structure after milling 180 h and gain a high thermal stability (the Tx around 689 ℃). Topological and thermodynamic factors governing the structural stability and phase formation are discussed via the mixing entropy, mixing enthalpy, atomic size difference, electronegativity difference and valence electron concentration, which can be beneficial to promoting the novel high entropy amorphous alloys design.

Формування фазового складу, структури та властивості електродугових покриттів системи Fe-Mn-Nb-Si-C для зміцнення робочих поверхонь землерийної техніки

Формування фазового складу, структури та властивості електродугових покриттів системи Fe-Mn-Nb-Si-C для зміцнення робочих поверхонь землерийної техніки

Enhanced piezoelectric properties and depolarization temperature in NBT-based ceramics by doping BT nanowires

(Na0.5Bi0.5)TiO3-(K0.5Bi0.5)TiO3–BaTiO3 ternary ceramic exhibits excellent piezoelectric properties, but its depolarization temperature is a longstanding obstacle for their practical applications. The improvement of depolarization temperature of (Na0.5Bi0.5)TiO3-based ceramics is usually companied by deterioration of piezoelectric properties. In this study, we use BaTiO3 nanowires to replace BaTiO3 solution in off-MPB 0.88(Na0.5Bi0.5)TiO3-0.06(K0.5Bi0.5)TiO3-0.06BaTiO3 ceramic. A narrower peak in tanδ-T curves is obtained and the depolarization temperature Td increased from 95 °C to 133 °C after BaTiO3 nanowires substituting for BaTiO3 solution. The promotion of Td is thought to be associated with that the BaTiO3 nanowires may pin the domain wall and suppress the dispersion of temperature induced FE-RE (AFE) phase transition. Meanwhile, the piezoelectric constant d33 enhanced from 105 to 192 pC/N simultaneously due to the formation of MPB phase structure and high ε33Pr value. The results proposed that the piezoelectric properties and depolarization temperature can be simultaneously improved in (Na0.5Bi0.5)TiO3-based ceramics by doping BaTiO3 nanowires into appropriate basic materials.

The Effect of Calcination Temperature on the Structure and Performance of Nanocrystalline Mayenite Powders.

The effect of calcination temperature on the structural properties and phase formation of synthesized CaO-Al2O3 nanopowder was investigated and discussed. The calcination products were identified by differential thermal analysis (DTA) and the crystalline phase formation was analyzed by X-ray diffraction (XRD). The obtained results showed that the crystallization started at 460 °C. Finally, the microstructures of the nanoparticles were observed by scanning (SEM) and transmission electron (TEM) microscopes. The investigation showed that an increase in the calcination temperature led to the appreciable increase in the crystallite size and the crystallinity of the final product. The obtained data confirmed that the prepared materials were mayenite with different surface area in the range of 71.18 m2/g to 10.34 m2/g after annealing in the temperature range of 470 °C to 960 °C.

Synthesis, structural, dielectric and magnetic properties of cobalt ferrite nanomaterial prepared by sol-gel autocombustion technique

Cubic spinel structured CoFe2O4 nanocrystalline material has been synthesized using the sol-gel auto combustion route. Structural parameters and phase formation were studied using room temperature powder X-ray diffraction (XRD). The result shows a pure cubic spinel structured sample formation with a lattice parameter of 8.4277 Å. Field emission scanning electron microscopy (FESEM) microstructural characterization revealed the nanocrystalline structure of the so synthesized sample with non-homogeneous grain sizes and grain shapes. Fourier transform infrared (FT-IR) characterization confirmed the spinel structure formation by exhibiting the cation stretching-vibrations at the tetrahedral and octahedral sites. The DC resistivity measurement has been carried out using a two-probe technique and confirmed the high resistive nature of the sample. The room temperature dielectric and AC properties were investigated in the frequency ranges of 100 Hz–5 MHz. The dielectric dispersion has been observed at lower frequencies. Higher magnetization value has been measured using the VSM technique.

Substrate effect on the structural phase formation and magnetic properties of α-Fe2O3 and Ti doped α-Fe2O3 thin films

We report the synthesis and magnetic properties of hematite (α-Fe2O3) and Ti doped hematite (α-Fe1.4Ti0.6O3) films. The films have been grown at 400 °C on different substrates by using Pulsed Laser Deposition technique. The as-grown film has been heated in the temperature range 600–730 °C either in air or vacuum. Microstructure of the films has been studied using X-ray diffraction pattern, Atomic force microscope, Field effect Scanning Electron Microscope, and magneto-optic Kerr effect (MOKE). Crystalline structure of the films has been stabilized either in rhombohedral phase or in cubic spinel phase depending on the type of substrates. The crystalline films have been found highly oriented on specific directions. Magnetic order of the films at room temperature has been studied using MOKE. The films on selected substrates have been used for a detailed study of low temperature magnetic properties. The temperature dependent magnetization of the films has exhibited bifurcation between zero field cooled and field cooled magnetic curves at all measurement temperatures (5–350 K). Magnetic spin order of the films has been affected by the nature of substrates. Some of the films with room temperature ferromagnetism or canted antiferromagnetism seem to be useful for spintronics applications.

Structural studies and exchange bias interaction in Sr+2 doped LaFeO3 synthesised via PVA based sol-gel method

Modification in the crystal structure often exhibits different functionalities and characteristics. In the present study it is demonstrated that Sr2+ modified lanthanum ferrite La(1-x)SrxFeO3 (x = 0, 0.02, 0.04 and 0.06) prepared using PVA based sol gel method shows unique structure and magnetic properties. Structural analysis and phase formation study was performed using X-ray diffraction data and various structural parameters were calculated using Rietveld refinement. It is observed that with the increase in Sr2+ content the structural parameters of LaFeO3 unit cell change. The FESEM and TEM studies were used to study the size and morphology of La(1-x)SrxFeO3 nanoparticles. Magnetic hysteresis measurement reveals the appearance of zero field cooled exchange bias in La(1-x)SrxFeO3, originating due to the interfacial exchange coupling between AFM/FM. In addition, the magnetization increases while exchange bias vanishes at higher strontium concentration. These results help in understanding the in-depth interfacial coupling interaction mechanism.

Investigating the influence of volumetric hydrophobization on the formation of phase composition of cement stone and its physical-mechanical properties

We have examined the influence of the most widely used silicon-organic surface water repellent GKZH-11K on the physical-mechanical properties and the phase structure formation of cement is the fact that the introduction of the surface water repellent GKZH-11K to the composition of cement slurry leads to the formation of dispersive water-repellent films of various levels (size). These films adsorb at the surface of cement grains, as well as at the surface of hydrated components of cement particles, Са(ОН)2, calcium sulphoaluminates. It was determined that the disperse hydrophobic films partially block the penetration of water into the surface of cement grains and alter the kinetics of hydration.This leads to a decrease in the degree of hydration and the content of Са(ОН)2 in cement stone, resulting in the reduced shrinkage at hardening. At the same time, the disperse films adsorbed on neighboring hydrated cement particles within the contacts occurred in the process of their condensation can form hydrogen and chemical relationships. This interaction between the particles' films, despite the reduction in the degree of hydration, leads to a decrease in water absorption, improving the strength of cement stone, which in this case is also determined by the number and area of contacts per unit volume of cement stone. The overlap of pores with hydrophobic chains decreases the permeability of cement stone throughout its entire volume, which contributes to the growth of operational reliability and durability of structures, particularly thin-walled. Using this admixture for volumetric hydrophobization could greatly prolong repair-free operation of thin-walled products and structures, as well as bring down cost as there is no need to apply materials to protect the surface of concrete.

Influence of insoluble component on C→T and Т→М phase transformations and structure formation under annealing of plasma-spray synthesized nanocrystalline powder systems (100-x)ZrO2 (3Y)+xAl2 O3 (x = 0 and 20 wt%). Part 2: Analysis of powders after annealing.

Influence of insoluble component on C→T and Т→М phase transformations and structure formation under annealing of plasma-spray synthesized nanocrystalline powder systems (100-x)ZrO2 (3Y)+xAl2 O3 (x = 0 and 20 wt%). Part 2: Analysis of powders after annealing.

Sintering of lunar regolith structures fabricated via digital light processing

Abstract Architectural and functional structures composed of lunar regolith-simulant CLRS-2 were fabricated via digital light processing and sintered at 1100 °C and 1150 °C under an air or argon atmosphere. This work is to investigate effects of atmosphere and temperature on mechanical properties, microstructure, and chemical composition of lunar regolith products. Samples sintered at 1150 °C in air underwent the highest sintering shrinkage and showed the best mechanical properties, likely due to the formation of glassy phase and dense structure following sintering. Conversely, argon-sintered samples exhibited lower density resulting from the lack of glassy phase. Phase analysis revealed varying chemical composition and therefore different underlying reaction mechanisms under two sintering atmospheres, indicating that sintering atmosphere significantly influences the microstructure and macroscopic properties of lunar regolith products.

Microstructural characterization and dielectric properties of single crystalline BaTi2O5 nanowires prepared by molten-salt method

BaTi2O5 (BT2) nanowires were successfully prepared via molten-salt method. The effects of synthesized temperature, dwell time, and molten salt concentration on the formation of BT2 nanowires were studied. X-ray diffraction patterns reveal that the BT2 nanowires crystallize in a monoclinic crystal structure. Neither the longer dwell time nor molten salt concentration has apparent influence on the formation of BT2 phase structure, whereas the synthesized temperature exerts great effect on the morphology of BT2 nanowires. One-dimensional morphology of the BT2 products was only obtained at a narrow temperature window (870–900 °C). At 970 °C, the morphology of BT2 nanowires was destroyed and they are broken into particles, growing as large flat crystals. The BT2 nanowires synthesized at 900 °C exhibit uniform morphology and grow in the [010] direction, which have an average diameter of 780 nm and length of 15 μm. The formation mechanism of BT2 nanowires in the MSS process is proposed. The BT2 nanowires exhibit the single-crystalline characteristics, as proven by high-resolution TEM images and electron diffraction patterns. Quantitative X-ray energy-dispersive spectroscopy analysis shows the BT2 nanowires having homogeneous chemical compositions, and their atomic cation ratio of Ba:Ti is 1:2.16. Dielectric properties of the BT2 nanowires synthesized at 900 °C are measured at room temperature with the frequency ranged from 102 to 106 Hz. The BT2 nanowires exhibit almost frequency independent dielectric behavior with dielectric constants of 28–31. The dielectric losses remain constant value of ~ 0.02 below 105 Hz, and increase up to 0.04 at 106 Hz.

Synthesis and Electrochemical Study of Mesoporous Nickel-Cobalt Oxides for Efficient Oxygen Reduction.

Development of a cost-effective and efficient electrocatalyst for the sluggish oxygen reduction reaction (ORR) is a crucial challenge for clean energy technologies. In this study, we have synthesized various Ni and Co oxide (NCO) nanomaterials via a facile coprecipitation, followed by the calcination method. The morphology of the formed NCO nanomaterials was controlled by varying the percentage of the Ni and Co precursors, leading to the formation of a template-free mesoporous spinel phase structure of Ni xCo3- xO4. It was found that the number of the octahedral site cations and the defect sites with lower oxygen in the spinel oxides can be tunable by taking appropriate ratios of the Ni and Co precursors. The optimized NCO nanomaterial exhibits superior electrocatalytic activity compared to the mono-metal oxides of NiO and Co3O4 with over 3 times higher current density and ∼0.250 V lower onset potential toward ORR in a 0.1 M KOH solution. Scanning electrochemical microscopy was utilized in mapping the activity of the catalyst and monitoring the ORR products, further confirming that a four-electron transfer pathway was facilitated by the NCO nanomaterial. Moreover, the developed mesoporous NCO nanomaterial exhibits a high methanol tolerance capability and long-term stability when compared to the commercial state-of-the-art Pt/C electrocatalyst. The improvement of the catalytic activity and stability of this advanced NCO nanomaterial toward ORR may be attributed to the facile accessible mesoporous structure, and the abundance of octahedral site cations and defective oxygen sites.

Fabrication of Li<sub>0.06</sub>(K<sub>0.5</sub>,Na<sub>0.5</sub>)<sub>0.94</sub>NbO<sub>3</sub> Nanofibers by Electrospinning Technique

In this work, Li0.06(K0.5,Na0.5)0.94NbO3(KNNL) nanofibers were synthesized by sol–gel process and electrospinning technique. The thermal behaviour ofelectrospun fibers was characterized by thermogravimetric analysis (TG) to obtain the calcination temperature range. The structural phase formation and microstructure were characterized by X-ray diffraction technique (XRD) and scanning electron microscopy (SEM), respectively. The crystal structure was identified by XRD as a single-phase perovskite structure, with orthorhombic symmetry. The microstructure shows that the diameters are in the range of 80–160 nm. The electrospun fibers were calcined from 500°C to 900°C and observed the fiber morphology. With increasing calcination temperature, the fiber diameters decreased until the temperature up to 900 °C the morphology change from cylinder to square or rectangular shape grains.

Structural, optical, magnetic and electrical properties of perovskite Sr1−xWxTiO3 (x = 0.01 and 0.03) prepared by SSR method ceramics

Tungsten doped with various concentrations (0, 1, and 3%) of strontium titanate ceramic sample was synthesized by a conventional solid state reaction method. The structural phase formation was examined by powder XRD technique and it revealed a single phase cubic perovskite structure of strontium titanate ceramic. The functional group and metal oxide chemical bonding of vibrations were seen to be present in the prepared ceramic samples and it was examined by Fourier transform infrared spectroscopy. The cubic perovskite structure formation and internal disorder parameter of the ceramic compounds were investigated by Raman spectrum. The surface morphology of the prepared ceramic sample was irregular, and its grain size was seen to be reduced, which was investigated by FESEM analysis. It was identified that UV–Visible Diffuse Reflectance Spectra revealed that the absorption for maximum level decreases with the doped ceramic sample. The elemental distribution of the chemical composites of doped ceramic sample was identified by EDX analysis. Dielectric constant was measured to be very low but conductivity level was good as the existence of low concentration defect and space charge polarization were present due to high dielectric constant at lower frequency.

Interfacial properties of lipid sponge-like nanoparticles and the role of stabilizer on particle structure and surface interactions.

The advantage of using nonlamellar lipid liquid crystalline phases has been demonstrated in many applications, such as drug delivery, protein encapsulation and crystallisation. We have recently reported that a mixture of mono- and diglycerides is able to form sponge-like nanoparticles (L3-NPs) with large enough aqueous pores to encapsulate macromolecules such as proteins. Here we use small angle neutron scattering (SANS) to reveal morphology, structural and chemical composition of these polysorbate 80 (P80) stabilized sponge phase nanoparticles, not previously known. Our results suggest that L3-NPs have a core-shell sphere structure, with a shell rich in P80. It was also found that even if P80 is mostly located on the surface, it also contributes to the formation of the inner sponge phase structure. An important aspect for the application and colloidal stability of these particles is their interfacial properties. Therefore, the interfacial behaviour of the nanoparticles on hydrophilic silica was revealed by Quartz crystal microbalance with dissipation (QCM-D) and neutron reflectivity (NR). Adsorption experiments reveal the formation of a thin lipid layer, with the dimension corresponding to a lipid bilayer after L3-NPs are in contact with hydrophilic silica. This suggests that the diglycerol monoleate/Capmul GMO-50/P80 particles reorganize themselves on this surface, probably due to interactions between P80 head group and SiO2.

DEFECTS IN METAL DURING PLASMA AND TIG SURFACING (REVIEW)

In the process of exploitation, such property of articles as working capacity most often depends on the quality and condition of the surface layer. Therefore, a complex approach that includes a multifactorial effect on phase formation and structure formation in metal systems with the use of modern equipment is of particular relevance. The quality of products, determined by a number of its mechanical properties, can be significantly reduced by the occurrence and spreading of defects in products in surfacing, welding and additive technologies that are associated with the use of highly concentrated energy sources, which is a significant problem.Preventing the occurrence of defects during surfacing is a priority and urgent task in modern machine-building production. The solution to this problem can be the selection of optimal deposition modes in accordance with the requirements for the quality of the welded layer, the mechanical properties of the material of the parts and the quality of the products as a whole.

Phase state diagram of a poly(amic acid)–solvent–nonsolvent system

Phase behavior and structure formation was studied using optical interferometry, nephelometry, and refractometry in the polymer–solvent–nonsolvent system for DMF solutions of two poly(amic acids): based on 3,3′,4,4′-benzophenonetetracarboxylic acid dianhydride and meta-phenylenediamine (PAA-1) and pyromellitic acid dianhydride and 4,4′-oxydianiline (PAA-2). Distilled water and its mixtures with DMF were used as a nonsolvent. According to the results of the study, isothermal cross sections of the phase state diagram in the threecomponent system were plotted, the position of the critical point, the spinodal, and the conodes were determined, the movement of the figurative points in the system was traced depending on the nonsolvent composition.