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1.
In this research work, the sintering characteristics of Al86Ni6Y4.5Co2La1.5 mechanically alloyed amorphous powders and milled melt spun ribbon have been compared. Mechanically alloyed amorphous powders were synthesized via 200?h high energy ball milling. Melt spun ribbons were synthesized by single roller melt spinning technique and grounded to powder form by ball milling. Mechanically induced partial crystallization occurred in the ribbons during milling. Significantly higher amount of contaminations such as carbon, oxygen and iron were observed in the mechanically alloyed amorphous powders compared to the milled ribbons. Both powders were consolidated via spark plasma sintering. Superior particle bonding was found in the sample consolidated from milled ribbons, ascribed to the lower amount of contamination that could not effectively restrict the viscous flow and diffusion of atoms. Various complex crystalline phases evolved in the sample consolidated from milled ribbon particles due to the presence of crystalline phases in the powders which acted as nucleation sites, whereas the amorphous phase was mostly retained in its counterpart. Vickers microhardness of the consolidated alloys from milled ribbon and mechanically alloyed amorphous powders were 3.60?±?0.13?GPa and 2.53?±?0.09?GPa, respectively. The higher hardness in the former case was attributed to the superior particle bonding and distribution of hard intermetallic phases in the amorphous matrix. 相似文献
2.
Spinel LiMn2O4 powder was prepared by a novel process of high-temperature ball milling. For comparison, the spinel LiMn2O4 powder was also synthesized by the traditional method of solid state reaction. It was found that high-temperature ball milling significantly decreased the synthesis temperature and time. LiMn2O4 with pure spinel phase could be successfully synthesized only by 2?h high-temperature ball milling at 500°C and 600°C. However, pure spinel LiMn2O4 could not be completely synthesized by 2?h solid state reaction at 800°C. The LiMn2O4 particles prepared by high-temperature ball milling are nano-sized (<100?nm) and much smaller than that prepared using solid state reaction. The electrochemical tests results indicated that the as-synthesized LiMn2O4 by 2?h high-temperature ball milling at 600°C showed a favorable initial discharge capacity of 124.2 mAh g?1 at current rate of 0.1 C and still retained a capacity of 119.8 mAh g?1 at 0.1 C after 80 continuous cycles from 0.1 to 2.0 C. 相似文献
3.
Mechanochemical activation of solids can lead to a strong increase in their activity as catalysts in heterogeneously catalyzed reactions. In the following, we report on the effects of solid catalyst activation during ball milling that lead to oscillatory behavior in CO and CO2 formation during propene oxidation. The oscillations arise under in situ ball milling conditions over chromium(III) oxide (Cr2O3) and cerium(IV) oxide (CeO2), respectively. The experiments were conducted under continuous gas flow at ambient pressure and temperature, using both a modified steel and a tungsten carbide milling vessel. Abrasion of particles from the steel milling vessel could be eliminated as the sole cause for the oscillations through substitution by a tungsten carbide milling vessel. The intensity and frequency of oscillations are shown to be dependent on the propene-to-oxygen ratio, the milling frequency, milling ball size and metal oxide used. Overall, Cr2O3 shows higher activity for oscillatory propene combustion under in situ mechanical activation than CeO2. 相似文献
4.
5.
Nano-hybrid materials of anatase and activated carbon were fabricated in a single step by a hydrothermal with ball milling
method (H with B) using a conventional autoclave and SiC balls at 180°C. To investigate the influence of ball milling and
activated carbon, a hydrothermal method without ball milling (H without B) and a carbonless hydrothermal method with ball
milling (Carbonless H with B) were performed. By comparing the three samples based on Transmission Electron Microscopy (TEM)
observation and Selected Area Electron Diffraction (SAED) analysis, it was revealed that TiO2 particles in the hybrid materials heterogeneously nucleate on the activated carbon and have a tendency of crystal growth
along the c axis under the given experimental condition. The crystal growth direction was controlled isotropically by assisting the ball
milling during reaction. The balls seem to act as a stirrer rather than a grinder for the sample containing the activated
carbon. 相似文献
6.
In this study, the synthesis of Ti2SC MAX phase by high energy ball milling, and the effects of heat treatment on ball milled powder was investigated. To this aim, a mixture of Ti, FeS2 (as sulfur source), and C according to Ti2SC stoichiometry, were ball milled by a planetary ball mill for different milling periods up to 10 h. The structural evolution, and the morphology of the products was studied by x-ray diffraction (XRD), and scanning electron microscopy (SEM) equipped with energy-dispersive spectroscopy (EDS), respectively. The results showed that after 10 h of ball milling, the raw materials reacted together and resulted in the formation of Ti2SiC and TiC phases. The ball milled powder was then compacted and heat treated at 1000 and 1200 °C. Heat treatment caused the progressing of synthesis reactions, and led to increasing the purity of Ti2SC phase. The heat-treated powder was leached in 1 M HCl for 2 h to remove iron from the product. The XRD results confirmed successful iron removal by leaching. SEM micrographs of the final product revealed the specific lamellar structure of MAX phases. Elemental mapping confirmed the homogeneous distribution of Ti, S and C elements. 相似文献
7.
The synthesis of In2O3-doped CaZrO3 by solid oxide and oxalate co-precipitation routes has been studied. The effects of using polymeric surfactants (PEG) and
ball milling on the synthesis were determined by characterizing the materials at various stages using SEM, XRD, FTIR and particle
size analysis. PEG addition and ball milling led to the formation of smaller particles which reduces the time and temperature
needed for perovskite formation. 相似文献
8.
A. Hamrita F. Ben Azzouz W. Dachraoui M. Ben Salem 《Journal of Superconductivity and Novel Magnetism》2013,26(4):879-884
The effect of Ag inclusion on the structure microstructure and the critical current density of the YBa2Cu3O7?δ sample prepared using the planetary ball milling process has been investigated. YBa2Cu3O7?δ ceramics have been synthesized in air by a solid state reaction method from an oxide precursor powder, which was prepared from the starting powders of Y2O3, Ba2CO3, and CuO via a one-step annealing process in air at 950 °C. After planetary ball milling for 4 h of the oxide precursor powders, it was mixed with an AgNO3 solution, and then was dried and uniaxially pressed, and subsequently annealed at 950 °C in air. Phase analysis by X-ray diffraction (XRD), granular structure examination by scanning electron microscopy (SEM), microstructure investigation by transmission electron microscopy (TEM) coupled with energy dispersive X-ray spectroscopy (EDXS) were carried out. To understand the effects of the ball milling on the pinning behavior, magnetic field and temperature dependences on a critical current density have been studied. Analyses show that Ag-milled YBCO samples exhibit higher values of critical current density in applied magnetic field compared to Ag-unmilled one. The better pinning properties of the Ag-milled samples are believed to be due to the microstructure of more fine and uniform distribution of silver and Y-deficient nanosized generated by ball milling. 相似文献
9.
Indium oxide-doped hematite xIn2O3·(1 ? x)??-Fe2O3 (x = 0.1?C0.7) nanostructure system was synthesized using mechanochemical activation by ball milling and characterized by XRD, simultaneous DSC?CTGA, and UV/Vis/NIR. The microstructure and thermal behavior of as obtained system were dependent on the starting In2O3 molar concentration x and ball milling time. XRD patterns yielded the dependence of lattice parameters and grain size as a function of ball milling time. After 12 h of ball milling, the completion of In3+ substitution of Fe3+ in hematite lattice occurs for x = 0.1, indicating that the solid solubility of In2O3 in hematite lattice is extended. For x = 0.3, 0.5, and 0.7, the substitutions between In3+ and Fe3+ into hematite and In2O3 lattice occur simultaneously. The lattice parameters a and c of hematite and lattice parameter a of indium oxide vary as a function of ball milling time. The changes of these parameters are due to ion substitutions between In3+ and Fe3+ and the decrease in the grain sizes. Ball milling has a strong effect on the thermal behavior and band gap energy of the as-obtained system. The hematite decomposition is enhanced due to the smaller hematite grain size. The crystallization of hematite and In2O3 was suppressed, with drops of enthalpy values due to the stronger solid?Csolid interactions after ball milling, which caused gradual In3+?CFe3+ substitution in hematite/In2O3 lattices. The band gap for hematite shifts to higher energy value, while that of indium oxide shifts to lower energy value after ball milling. 相似文献
10.
《Materials Letters》2004,58(22-23):2824-2828
Systematic study on Ni–15% Fe–5% Mo by high energy ball milling of elemental Mo powder and pre-alloyed intermetallic FeNi3 has been done to understand the formation kinetics during ball milling. X-ray powder diffraction (XRPD) has been employed to study the structure evolution. Mo atoms were found to dissolve into FeNi3 within 40 h of milling. The speed of the diffusion of Mo atoms into FeNi3 alloy was very slow as analyzed using the Johnson–Mehl–Avrami (JMA) equation. The substitution process destroyed the long-range FeNi3 and NiMo bonds were formed. This change caused a decrease in magnetization. 相似文献
11.
Kollár P. Petrovič P. Fechová E. Füzer J. Konč M. Kováč J. 《Journal of Materials Synthesis and Processing》2000,8(5-6):301-304
We have studied the influence of the long-term (1700 h) milling on the structure and magnetic properties of Fe73.5Si13.5Cu1Nb3B9 powder prepared in a vibratory mill. Three samples (in amorphous state, partially crystallized state, and mixed of pure elements) of the same chemical content were prepared. We found that the structure and magnetic properties significantly depend on the milling time. The coercivity of the sample prepared from pure elements monotonously increases with increased milling time. The coercivity of the samples milled from the ribbon increases to its maximum for milling time of 800 h and then decreases. 相似文献
12.
《Advanced Powder Technology》2020,31(1):40-50
In this paper, a ball milled Cu2O-ZnO nano-photocatalyst with good photocatalytic performance in visible light range was prepared. Effect of ZnO presence and ball milling of Cu2O on the structure, microstructure, optical properties and photocatalytic performance were studied. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), high resolution transmission electron microscopy (HRTEM), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) analysis and UV–Vis spectrophotometer were used as characterization techniques. FESEM results indicated that ball milling of Cu2O changed the morphology of Cu2O-ZnO composite. The uniform formation of ZnO particles with average size of 30 nm over the Cu2O surface was observed. The formation of p-n heterostructure with good contact between Cu2O and ZnO nanoparticles was found by HRTEM image. Ball milling of Cu2O promotes visible light absorption and reduction band gap to 1.9 eV in Cu2O-ZnO photocatalyst. Intensity of PL spectra for the ball milled Cu2O-ZnO photocatalyst was obviously lower. Ball milled Cu2O-ZnO photocatalyst shows the highest photocatalytic activity and degradation efficiency of 98% was obtained for 2 mg/L methylene blue (MB) solution after 240 min. The kinetics of the photodegradation was followed the Langmuir-Hinshelwood (L-H) model and degradation rates were decreased by increase of MB concentration. In the case of ball milled Cu2O and presence of ZnO, the MB degradation kinetics was two times faster. 相似文献
13.
《Advanced Powder Technology》2023,34(1):103919
The study of the influence of the duration of preliminary high-energy ball milling on the features of the structural-phase state and the level of microhardness of consolidated Ni3Al samples obtained by the method of spark plasma sintering has been carried out. It was found that the inhomogeneous state of the precursor from the 3Ni-Al powder mixture in the case of preliminary ball milling of a short duration (1 min) is a cause of the formation of an inhomogeneous structural-phase state of the consolidated Ni3Al sample. An increase in the duration of high-energy ball milling provides a homogeneous phase composition, promotes the refinement of the grain structure and an increase in the microhardness values of the obtained Ni3Al samples. The main factors determining the processes of structural-phase transformation during the formation of Ni3Al under the conditions of spark plasma sintering, depending on the preliminary high-energy ball milling, are revealed. It is shown that grain boundary strengthening is the one of the effective mechanisms for increasing the strength of the material under study. 相似文献
14.
Titanium and carbon powder mixtures with compositions of Ti100−x
C
x
(x = 50, 40, 30) were milled under a helium atmosphere using a magneto ball mill. Controlled ball milling was performed in a
higher energy impact mode and a lower energy shearing mode. For Ti50C50 and Ti60C40 powder mixtures milled in impact mode, TiC was formed via a mechanically-induced self-propagating reaction (MSR). When milling
Ti70C30 in impact mode, the reaction to form TiC proceeded gradually as milling progressed; indicating that, for milling conditions
that lead to the formation of TiC via MSR, a minimum carbon content is required to sustain the self-propagating reaction to
form TiC. Milling in shearing mode resulted in the gradual formation of TiC during milling. This study found that increasing
the carbon content of the starting powder mixture slowed the milling process. Replacing the activated carbon starting powder
with high purity graphite was found to have little effect on the ignition time; indicating that the slowing of the milling
process is not due to graphite acting as a lubricant during milling. Rather, this slowing of the milling process is most likely
due to an increased carbon content resulting in an increase in the volume of the powder mixture. This would have a similar
effect during milling to decreasing the ball:powder weight ratio (BPR), which is known to slow the milling process. 相似文献
15.
Y. Slimani E. Hannachi M. Zouaoui F. Ben Azzouz M. Ben Salem 《Journal of Superconductivity and Novel Magnetism》2018,31(8):2339-2348
Superconducting samples of type Y3Ba5Cu8O18±δ were elaborated by using a planetary high-energy ball milling (HEBM) technique with various parameters. Phases, microstructure, and superconductivity have been examined using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and electrical resistivity measurements. SEM investigation shows the occurrence of nanoentities embedded into the superconducting matrix for samples prepared by a ball milling technique. The main objective of this study is to investigate the influence of ball milling parameters on the fluctuation-induced conductivity (FIC). The electrical resistivity versus temperature, ρ(T), above T c was analyzed using Lawrence–Doniach (LD) and Aslamazov–Larkin (AL) models. Different fluctuation regimes indicated by short-wave fluctuation (SWF) and three-dimensional (3D), two-dimensional (2D), one-dimensional (1D), and critical region (CR) fluctuations were identified. The coherence length at zero temperature, the effective layer thickness, the critical magnetic fields, and the critical current densities are determined. The superconducting parameters strongly depend on the planetary ball milling technique, and the results are explained in relevancy to the microstructure. It was found that the achievement of a microstructure with well-dispersed nanoentities is an effective way for introducing pinning centers for enhancing critical current density and flux pinning capability of bulk Y-358. 相似文献
16.
Monica Sorescu Tianhong Xu Johanna D. Burnett Jennifer A. Aitken 《Journal of Materials Science》2011,46(20):6709-6717
LaFeO3 perovskite was synthesized mechanochemically through ball milling of La2O3 and Fe2O3 in stoichiometric ratio. X-ray powder diffraction (XRPD), simultaneous differential scanning calorimetry and thermogravimetry
analysis (DSC–TGA), M?ssbauer spectroscopy, scanning electron microscopy (SEM), and optical diffuse reflectance spectroscopy
were combined for a detailed study of the growth mechanism of LaFeO3 perovskite during the ball milling process. The XRPD results showed that La2O3 is unstable when exposed to air. Both La2O3 and La(OH)3 phases coexist under the ball milling process, indicating that La2O3 or La(OH)3 can be used to produce LaFeO3. The formation of LaFeO3 perovskite was evident after only 2 h of milling and the amount of LaFeO3 gradually increased with the increase of ball milling time. After 12 h of ball milling, single phase LaFeO3 was formed. The M?ssbauer spectroscopy studies show that the spectrum of the formed LaFeO3 phase consists of three sextets and one doublet, indicating the wide distribution of LaFeO3 particle sizes and some of the smaller particles having superparamagnetic properties. This is in good agreement with the
SEM images, which show that the formed LaFeO3 phase consists of nanometer-sized particles and micrometer-sized agglomerates. The formation of LaFeO3 phase was mainly caused by the La3+ substitution of Fe3+ in Fe2O3 lattice. Optical diffuse reflectance spectroscopy studies show that the formed LaFeO3 phase has semiconductor properties, with the band gap energy ~2.67 eV. 相似文献
17.
《Advanced Powder Technology》2014,25(3):978-982
In this study, nano-crystalline vanadium carbide was synthesized through reduction of V2O5 by carbon and Ca using high energy ball milling and subsequent heat treatment. Vanadium pentoxide, calcium and carbon black were placed in a planetary ball mill and sampled after different milling times. The activated powders were synthesized by microwave heating at temperatures 800 °C. XRD and FESEM were used for characterization of synthesized powder. On the basis of obtained results, the synthesized V8C7 crystallites were in the scale of nanometers and the lattice parameter had some deviation from the standard value. Furthermore, investigations showed that at higher milling time, the amorphization degree of V4C3 phase increased, while the degree of crystallite decreased. 相似文献
18.
Mechanochemical processing is a novel technique for the synthesis of nano-sized materials. This research is based on the production of Al2O3–TiB2 nanocomposite powder using mechanochemical processing. For this purpose, a mixture of aluminum, titanium and boron oxide powders was subjected to high energy ball milling. The structural evaluation of powder particles after different milling times was conducted by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results showed that during ball milling the Al/B2O3/Ti reacted with a combustion mode producing Al2O3–TiB2 nanocomposite. In the final stage of milling, the crystallite sizes of Al2O3 and TiB2 were estimated to be less than 50 nm. 相似文献
19.
S. T. Gulati 《Journal of Materials Science》1976,11(4):631-637
The strength measurements for Corning Code 8871 glass ribbon with a rectangular crosssection measuring 0.22 in.×0.002 in. are presented. Owing to the narrow width of the ribbon, tensile strength measurements were carried out only in the longitudinal direction. To establish the isotropy of ribbon strength, flexure tests were conducted in both the longitudinal and transverse directions. It was found that in the as-manufactured condition, the transverse strength is lower than the longitudinal strength, indicating preferred orientation of flaws introduced during manufacturing. After etching in 10% HF/15% HNO3 solution for different lengths of time, the longitudinal and transverse flexural strengths increased with etch time, reaching an asymptotic value after 20 sec. The transverse strength value, after etching, was generally higher than the longitudinal strength, partly due to the considerably smaller surface area exposed to tension and partly due to the uncertainties in measurement of chord length. The anisotropy of ribbon strength in the as-manufactured condition could partly account for the anisotropic strength of ribbonreinforced composites as reported in the literature [4, 5]. 相似文献
20.
The effect of cold rolling and ball milling on the hydrogen sorption properties of CaNi5 was investigated with a special emphasis on the first hydrogenation. We compared cold rolling for 5, 12, and 25 rolling passes in the air with ball milling in argon for 30 and 60 min. Results show that 15 min of ball milling had a positive effect on the first hydrogen absorption, but further milling to 60 min made the sample almost impermeable to hydrogen. Cold rolling had a positive effect on first hydrogenation. We found that cold rolling greatly reduces the particle size as well as the crystallite size. We also found that dehydrogenation under 5 kPa of hydrogen at 323 K was not complete. Two partially hydride phases remained: CaNi5H and Ca2Ni7H x . 相似文献