Transmission Electron Microscopy Studies of X210CrW12 and 100CR6 Thixo-Cast Steels

2012 ◽  
Vol 186 ◽  
pp. 311-314 ◽  
Author(s):  
Lukasz Rogal ◽  
Jan Dutkiewicz
Keyword(s):  
Chemical Composition ◽  
Liquid Fraction ◽  
Eutectic Mixture ◽  
Residual Austenite ◽  
Bearing Steel ◽  
Transmission Electron ◽  
Cast Steels ◽  
Contamination Effect ◽  
Cold Worked ◽  
Average Size

Two kinds of deformed carbon steel were used as a feedstock for thixoforming: X210CrW12 tool steel cold worked, of composition 2,1 %C, 10,5 %Cr, 0,7 %W, 0,4 %Si (all in weight %), and bearing steel 100Cr6: (0,9% C, 1,4% Cr, 0,4% Mn, 0,3% Si, 0,2% Cu). The microstructures of X210CrW12 steel after thixoforming process at temperature of 1230°C, performed at 30 % of liquid show presence of globular grains (average size from 30 µm 50 µm) surrounded by the eutectic mixture. Measured chemical composition of the austenite in globules was: 2,5% C, 0,4% Si, 0,7% Mn, 12% Cr, 1,3% W, 0,1%V, 87% Fe and that of the eutectic mixture: 5%C, 0,4% Si, 0,6%, Mn, 1,1%, W, 17,5% Cr, 75,4% Fe in thixocast of X210CrW12 steel. Measured carbon content is too high, most probably due to contamination effect. TEM studies of this steel after thixoforming shows that the eutectic mixture consists of ferrite α-Fe and Cr7C3 carbides. Thixoforming of 100Cr6 bearing steel was conducted at temperature of 1420°C at about 25 % of liquid fraction. Thixocast microstructure consists of globular grains consisting of martensite needles and residual austenite (20 μm to 40 μm in size and average composition 0,9%C, 1,4 %Cr, 0,5%Mn, 0,3%Si). The chemical composition of the eutectic is following: 2,4% C, 2,6% Cr, 0,2%Si, 0,6%Mn.

A TEM investigation of a hyper-eutectic lead-tin alloy

1988 ◽  
Vol 46 ◽  
pp. 562-563
Author(s):  
John A. Sutliff
Keyword(s):  
Volume Diffusion ◽  
Eutectic Mixture ◽  
Precipitation Reaction ◽  
Directionally Solidified ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Diffusion Controlled ◽  
Discontinuous Precipitation Reaction ◽  
Controlled Precipitation

Near-eutectic Pb-Sn alloys are important solders used by the electronics industry. In these solders, the eutectic mixture, which solidifies last, is the important microstructural consituent. The orientation relation (OR) between the eutectic phases has previously been determined for directionally solidified (DS) eutectic alloys using x-ray diffraction or electron chanelling techniques. In the present investigation the microstructure of a conventionally cast, hyper-eutectic Pb-Sn alloy was examined by transmission electron microscopy (TEM) and the OR between the eutectic phases was determined by electron diffraction. Precipitates of Sn in Pb were also observed and the OR determined. The same OR was found in both the eutectic and precipitation reacted materials. While the precipitation of Sn in Pb was previously shown to occur by a discontinuous precipitation reaction,3 the present work confirms a recent finding that volume diffusion controlled precipitation can also occur.Samples that are representative of the solder's cast microstructure are difficult to prepare for TEM because the alloy is multiphase and the phases are soft.

scholarly journals Obtaining Silicon Oxide Nanoparticles Doped with Fluorine and Gold Particles by the Pulsed Plasma-Chemical Method

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Galina Kholodnaya ◽  
Roman Sazonov ◽  
Denis Ponomarev ◽  
Igor Zhirkov
Keyword(s):  
Chemical Synthesis ◽  
Silicon Oxide ◽  
Fine Particles ◽  
Chemical Reactor ◽  
Beam Diameter ◽  
Pulsed Plasma ◽  
Plasma Chemical ◽  
Plasma Chemical Synthesis ◽  
Transmission Electron ◽  
Average Size

This paper presents a study on pulsed plasma-chemical synthesis of fluorine- and gold-doped silicon oxide nanopowder. The gold- and fluorine-containing precursors were gold chloride (AuCl3) and sulphur hexafluoride (SF6). Pulsed plasma-chemical synthesis is realized on the laboratory stand, including a plasma-chemical reactor and TEA-500 electron accelerator. The parameters of the electron beam are as follows: 400–450 keV electron energy, 60 ns half-amplitude pulse duration, up to 200 J pulse energy, and 5 cm beam diameter. We confirmed the composite structure of SixOy@Au by using transmission electron microscopy and energy-dispersive spectroscopy. We determined the chemical composition and morphology of synthesized SixOy@Au and SixOy@F nanocomposites. The material contained a SixOy@Au carrier with an average size of 50–150 nm and a shell of fine particles with an average size of 5–10 nm.

scholarly journals Study on Structure, Thermal Behavior, and Viscoelastic Properties of Nanodiamond-Reinforced Poly (vinyl alcohol) Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1426
Author(s):  
Tomáš Remiš ◽  
Petr Bělský ◽  
Tomáš Kovářík ◽  
Jaroslav Kadlec ◽  
Mina Ghafouri Azar ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Analysis ◽  
Single Step ◽  
Poly Vinyl Alcohol ◽  
Scanning Calorimetry ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Primary Particles ◽  
Solution Casting Method ◽  
Average Size

In this work, advanced polymer nanocomposites comprising of polyvinyl alcohol (PVA) and nanodiamonds (NDs) were developed using a single-step solution-casting method. The properties of the prepared PVA/NDs nanocomposites were investigated using Raman spectroscopy, small- and wide-angle X-ray scattering (SAXS/WAXS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). It was revealed that the tensile strength improved dramatically with increasing ND content in the PVA matrix, suggesting a strong interaction between the NDs and the PVA. SEM, TEM, and SAXS showed that NDs were present in the form of agglomerates with an average size of ~60 nm with primary particles of diameter ~5 nm. These results showed that NDs could act as a good nanofiller for PVA in terms of improving its stability and mechanical properties.

scholarly journals Structural Factors Inducing Cracking of Brass Fittings

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3255
Author(s):  
Lenka Kunčická ◽  
Michal Jambor ◽  
Adam Weiser ◽  
Jiří Dvořák
Keyword(s):  
Chemical Composition ◽  
Plastic Flow ◽  
Beta Phase ◽  
Alpha Phase ◽  
Structural Factors ◽  
Transmission Electron ◽  
Medical Gas ◽  
Hot Die Forging ◽  
Multiple Step

Cu–Zn–Pb brasses are popular materials, from which numerous industrially and commercially used components are fabricated. These alloys are typically subjected to multiple-step processing—involving casting, extrusion, hot forming, and machining—which can introduce various defects to the final product. The present study focuses on the detailed characterization of the structure of a brass fitting—i.e., a pre-shaped medical gas valve, produced by hot die forging—and attempts to assess the factors beyond local cracking occurring during processing. The analyses involved characterization of plastic flow via optical microscopy, and investigations of the phenomena in the vicinity of the crack, for which we used scanning and transmission electron microscopy. Numerical simulation was implemented not only to characterize the plastic flow more in detail, but primarily to investigate the probability of the occurrence of cracking based on the presence of stress. Last, but not least, microhardness in specific locations of the fitting were examined. The results reveal that the cracking occurring in the location with the highest probability of the occurrence of defects was most likely induced by differences in the chemical composition; the location the crack in which developed exhibited local changes not only in chemical composition—which manifested as the presence of brittle precipitates—but also in beta phase depletion. Moreover, as a result of the presence of oxidic precipitates and the hard and brittle alpha phase, the vicinity of the crack exhibited an increase in microhardness, which contributed to local brittleness.

scholarly journals Upconversion Luminescence of Silica–Calcia Nanoparticles Co-doped with Tm3+ and Yb3+ Ions

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 937
Author(s):  
Katarzyna Halubek-Gluchowska ◽  
Damian Szymański ◽  
Thi Ngoc Lam Tran ◽  
Maurizio Ferrari ◽  
Anna Lukowiak
Keyword(s):  
Energy Transfer ◽  
Near Infrared ◽  
Upconversion Luminescence ◽  
Sol Gel ◽  
Emission Spectra ◽  
Transmission Electron ◽  
Characteristic Emission ◽  
Diffraction Patterns ◽  
Size Of Particles ◽  
Average Size

Looking for upconverting biocompatible nanoparticles, we have prepared by the sol–gel method, silica–calcia glass nanopowders doped with different concentration of Tm3+ and Yb3+ ions (Tm3+ from 0.15 mol% up to 0.5 mol% and Yb3+ from 1 mol% up to 4 mol%) and characterized their structure, morphology, and optical properties. X-ray diffraction patterns indicated an amorphous phase of the silica-based glass with partial crystallization of samples with a higher content of lanthanides ions. Transmission electron microscopy images showed that the average size of particles decreased with increasing lanthanides content. The upconversion (UC) emission spectra and fluorescence lifetimes were registered under near infrared excitation (980 nm) at room temperature to study the energy transfer between Yb3+ and Tm3+ at various active ions concentrations. Characteristic emission bands of Tm3+ ions in the range of 350 nm to 850 nm were observed. To understand the mechanism of Yb3+–Tm3+ UC energy transfer in the SiO2–CaO powders, the kinetics of luminescence decays were studied.

scholarly journals Green Synthesized Silver Nanoparticles Immobilized on Activated Carbon Nanoparticles: Antibacterial Activity Enhancement Study and Its Application on Textiles Fabrics

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3790
Author(s):  
Pratama Jujur Wibawa ◽  
Muhammad Nur ◽  
Mukhammad Asy’ari ◽  
Wijanarka Wijanarka ◽  
Heru Susanto ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Activated Carbon ◽  
Aloe Vera ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
E Coli ◽  
Transmission Electron ◽  
Average Size ◽  
Green Synthesized Silver Nanoparticles

This research aimed to enhance the antibacterial activity of silver nanoparticles (AgNPs) synthesized from silver nitrate (AgNO3) using aloe vera extract. It was performed by means of incorporating AgNPs on an activated carbon nanoparticle (ACNPs) under ultrasonic agitation (40 kHz, 2 × 50 watt) for 30 min in an aqueous colloidal medium. The successful AgNPs synthesis was clarified with both Ultraviolet-Visible (UV-Vis) and Fourier Transform Infrared (FTIR) spectrophotometers. The successful AgNPs–ACNPs incorporation and its particle size analysis was performed using Transmission Electron Microscope (TEM). The brown color suspension generation and UV-Vis’s spectra maximum wavelength at around 480 nm confirmed the existence of AgNPs. The particle sizes of the produced AgNPs were about 5 to 10 nm in the majority number, which collectively surrounded the aloe vera extract secondary metabolites formed core-shell like nanostructure of 8.20 ± 2.05 nm in average size, while ACNPs themselves were about 20.10 ± 1.52 nm in average size formed particles cluster, and 48.00 ± 8.37 nm in average size as stacking of other particles. The antibacterial activity of the synthesized AgNPs and AgNPs-immobilized ACNPs was 57.58% and 63.64%, respectively (for E. coli); 61.25%, and 93.49%, respectively (for S. aureus). In addition, when the AgNPs-immobilized ACNPs material was coated on the cotton and polyester fabrics, the antibacterial activity of the materials changed, becoming 19.23% (cotton; E. coli), 31.73% (polyester; E. coli), 13.36% (cotton; S. aureus), 21.15% (polyester; S. aureus).

scholarly journals ZnSe Quantum Dots through a Facile one Pot Synthesis Process

2015 ◽  
Vol 34 ◽  
pp. 73-78
Author(s):  
Irtiqa Syed ◽  
Santa Chawla
Keyword(s):  
Quantum Dots ◽  
Band Gap ◽  
Quantum Confinement Effect ◽  
Hexagonal Phase ◽  
Fluorescence Decay ◽  
Synthesis Process ◽  
One Pot ◽  
One Pot Synthesis ◽  
Transmission Electron ◽  
Average Size

A novel one pot synthesis approach in oleic acid medium was employed to obtain monophasic ZnSe quantum dots (QD) of average size 3.7nm. The QDs were well crystalline in hexagonal phase as revealed by x-ray diffraction and high resolution transmission electron microscopy (HRTEM) studies. The ZnSe QDs exhibit sharp emission peak in the blue (465nm) with 385picosecond fluorescence decay time. The theoretical band gap corresponding to 3.7nm ZnSe QDs matched well with the measured 3.11eV band gap of synthesized QDs which thus showed quantum confinement effect.

The effect of silver concentration and calcination temperature on structural and optical properties of ZnO:Ag nanoparticles

2015 ◽  
Vol 29 (01) ◽  
pp. 1450254 ◽  
Author(s):  
M. Shayani Rad ◽  
A. Kompany ◽  
A. Khorsand Zak ◽  
M. E. Abrishami
Keyword(s):  
Calcination Temperature ◽  
Sol Gel ◽  
Visible Emission ◽  
X Ray Diffraction ◽  
Ag Nps ◽  
Zno Nps ◽  
Calcination Temperatures ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Average Size

Pure and silver added zinc oxide nanoparticles ( ZnO -NPs and ZnO : Ag -NPs) were synthesized through a modified sol–gel method. The prepared samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. In the XRD patterns, silver diffracted peaks were also observed for the samples synthesized at different calcination temperatures of 500°C, 700°C, 900°C except 1100°C, in addition to ZnO . TEM images indicated that the average size of ZnO : Ag -NPs increases with the amount of Ag concentration. The PL spectra of the samples revealed that the increase of Ag concentration results in the increase of the visible emission intensity, whereas by increasing the calcination temperature the intensity of visible emission of the samples decreases.

A novel electrochemical comparative sensing interface of MgO nanoparticles synthesized by different methods

2017 ◽  
Vol 233 (3) ◽  
pp. 753-762 ◽  
Author(s):  
Utkarsh Jain ◽  
CS Pundir ◽  
Shaivya Gupta ◽  
Nidhi Chauhan
Keyword(s):  
Electrochemical Impedance ◽  
Chemical Reduction ◽  
Cost Effective ◽  
Green Technology ◽  
Mgo Nanoparticles ◽  
Transmission Electron ◽  
Impedance Spectroscopy Study ◽  
Vis Spectroscopy ◽  
Reduction Methods ◽  
Average Size

Recent advancements in nanotechnology, for the biosynthesis of metal nanoparticles through enormous techniques, showed multidimensional developments. One among many facets of nanotechnology is to procure and adopt new advancements for green technology over chemical reduction synthesis. This adaptation for acquiring green nanotechnology leads us to a new dimension of nanobiotechnology. In order to imply one such efforts, in this study the emphasis is being laid on the synthesis of MgO nanoparticles using green technology and eliminating chemical reduction methods. Different characterization techniques such as UV–Vis spectroscopy, transmission electron microscopy, and dynamic light scattering were used to carry out the experiments. The average size of MgO nanoparticles were obtained in the range of 85–95 nm, when synthesized by various sources. The extracts of plants were capable of producing MgO nanoparticles efficiently and exhibited good results during cyclic voltammetry and electrochemical impedance spectroscopy study. The electrode modified with MgO nanoparticles (plant extract) showed good stability (90 days) and high conductivity. This study reports cost-effective and environment-friendly method for synthesis of MgO nanoparticles using plant extracts. The process is rapid, simple, and convenient and can be used as an alternative to chemical method.

SYNTHESIS AND CHARACTERIZATION OF FERROELECTRIC NANOCRYSTAL POWDERS OF SrBi2Ta2O9 BY A POLYMERIZABLE COMPLEX METHOD

2005 ◽  
Vol 19 (15n17) ◽  
pp. 2514-2519 ◽  
Author(s):  
JIN-BO CHENG ◽  
AI-DONG LI ◽  
QI-YUE SHAO ◽  
YUE-FENG TANG ◽  
DI WU
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Thermal Analyses ◽  
Water Soluble ◽  
Complex Method ◽  
Powder Synthesis ◽  
Conventional Solid State Reaction ◽  
Transmission Electron ◽  
Average Size

Ferroelectric nanocrystal powders of SrBi2Ta2O9 (SBT) have been first prepared by a polymerizable complex (PC) route. The bismuth powder, strontium carbonate, and water-soluble tantalum oxalate solution were used as starting materials. Thermal analyses (TGA and DSC), x-ray diffraction (XRD), transmission electron microscopy (TEM), and conventional BET method were explored to characterize the structure, morphology, and specific surface area of PC-derived SBT powders calcined at 500-850 °C. As control samples, SBT powders were also fabricated by metalorganic decomposition (MOD) method. The XRD and TEM results indicate that high pure and well crystalline powders can be obtained at 650 °C with a average size of 50 nm. The PC-derived powder has much larger surface area than MOD-derived powder. The BET value of PC and MOD powder at 750 °C for 2h is 6.7 and 1.5m2/g, respectively. The specific surface area of powder prepared by conventional solid-state reaction is quite low, typically less than 1.5m2/g. Therefore, the feasibility of the polymerizable complex route is demonstrated in the powder synthesis of SBT with large surface area.

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