Analysis of Ground Dolomite: Effect of Grinding Time on the Production of Submicron Particles

2014 ◽  
Vol 679 ◽  
pp. 145-148 ◽  
Author(s):  
N.A. Nik Nur Azza ◽  
Hui Lin Ong ◽  
Hidayu Jamil Noorina ◽  
Hazizan Md Akil ◽  
S.T. Sam
Keyword(s):  
High Energy ◽  
Submicron Particles ◽  
X Ray Diffraction ◽  
Particle Size Reduction ◽  
Structural Pattern ◽  
Dolomite Sample ◽  
The Impact ◽  
Sem Morphology ◽  
Harmful Effects ◽  
Grinding Time

This paper discusses the effect of grinding time on the production of submicron dolomite by using the impact and abrasion technique of high energy planetary ball mill. It is known that grinding process leads to surface activation other than exhibiting particle size reduction. Most of the energy applied during the process will be dissipated as heat that could lead to harmful effects to the structural pattern of the ground material. Thus in order to study the detrimental effects of grinding towards submicron dolomite, sample was ground at 400 rpm speed with various grinding time; 0.5h, 1h, 2h, 5h, 10h and 20h. It was confirmed using X-Ray Diffraction (XRD) method that the crystalline structure of dolomite did not deform even after 20h of grinding time, thus maintained its crystallinity. The morphological structures of ungrind and ground raw dolomite were shown by Scanning Electron Microscope (SEM) morphology.

scholarly journals Investigation of the impact of mechanical activation on synthesis of the MgO-TiO2 system

2021 ◽  
pp. 22-22
Author(s):  
Natasa Djordjevic ◽  
Milica Vlahovic ◽  
Sanja Martinovic ◽  
Slavica Mihajlovic ◽  
Nenad Vusovic ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Titanium Dioxide ◽  
Diffraction Analysis ◽  
Mechanical Activation ◽  
High Energy ◽  
Composition Analysis ◽  
X Ray Diffraction ◽  
Magnesium Titanate ◽  
X Ray ◽  
The Impact

In this study, a mixture of magnesium oxide and titanium dioxide was mechanically activated in order to investigate the possibility of mechanochemical synthesis of magnesium titanate. Mechanical activation was performed for 1000 min in a high-energy vibro mill (type MH954/3, KHD Humboldt Wedag AG, Germany). The mill is equipped with housing having a horizontally placed shutter. The cylindrical stainless steel working vessel, with inner dimensions of 40 mm in height and 170 mm in diameter, has working elements consisting of two free concentric stainless steel rings with a total weight of 3 kg. The engine power is 0.8 kW. Respecting the optimal amount of powder to be activated of 50-150 g and the stoichiometric ratio of the reactants in the equation presenting the chemical reaction of magnesium titanate synthesis, the starting amounts were 20.2 g (0.5 mol) of MgO and 39.9 g (0.5 mol) TiO2. During the experiments, X-ray diffraction analysis of the samples taken from the reaction system after 60, 180, 330, and 1000 min of mechanical activation was performed. Atomic absorption spectrophotometry was used for chemical composition analysis of samples taken at different activation times. Based on the X-ray diffraction analysis results, it can be concluded that the greatest changes in the system took place at the very beginning of the mechanical activation due to the disturbance of the crystal structure of the initial components. X-ray diffraction analysis of the sample after 1000 min of activation showed complete amorphization of the mixture, but diffraction maxima characteristic for magnesium titanate were not identified. Therefore, the mechanical activation experiments were stopped. Evidently, the energy input was not sufficient to overcome the energy barrier to form a new chemical compound - magnesium titanate. The failure to synthesize magnesium titanate is explained by the low negative Gibbs energy value of -25.8 kJ/mol (despite the theoretical possibility that the reaction will happen), as well as by the amount of mechanical energy entered into the system during activation which was insufficient to obtain the reaction product. Although the synthesis of MgTiO3 was not achieved, significant results were obtained which identify models for further investigations of the possibility of mechanochemical reactions of alkaline earth metals and titanium dioxide.

Measurement of the Strain Distribution in Notch Tip Hydrides With High Energy X-Ray Diffraction and the Impact on Overload Modeling

2010 ◽  
Author(s):  
Matthew Kerr ◽  
Stephanie Tracy ◽  
Mark R. Daymond ◽  
Richard A. Holt ◽  
Jonathon D. Almer
Keyword(s):  
Finite Element ◽  
Strain Distribution ◽  
Process Zone ◽  
High Energy ◽  
X Ray Diffraction ◽  
Strain Fields ◽  
X Ray ◽  
Pressure Tubes ◽  
Notch Tip ◽  
The Impact

The formation of notch-tip hydrides in CANDU® Zr-2.5Nb pressure tubes can significantly reduce their resistance to fracture, particularly during overload conditions. This paper outlines recent high energy X-ray diffraction measurements of notch tip strain fields in Zr-2.5Nb specimens, during both hydride growth and overload. The use of this data to validate continuum Finite Element (FE) and possible inclusion in ‘Process Zone’ models of hydride fracture are also discussed.

scholarly journals High-Energy Mechanical Milling-Driven Reamorphization in Glassy Arsenic Monoselenide: On the Path of Tailoring Special Molecular-Network Glasses

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4478
Author(s):  
Yaroslav Shpotyuk ◽  
Pavlo Demchenko ◽  
Oleh Shpotyuk ◽  
Valentina Balitska ◽  
Catherine Boussard-Pledel ◽  
...  
Keyword(s):  
High Energy ◽  
Range Order ◽  
Bragg Diffraction ◽  
X Ray Diffraction ◽  
Intermediate Range ◽  
Intermediate Range Order ◽  
Extended Range ◽  
Modeling Code ◽  
The Impact ◽  
Network Glasses

The impact of high-energy milling on glassy arsenic monoselenide g-AsSe is studied with X-ray diffraction applied to diffuse peak-halos proper to intermediate- and extended-range ordering revealed in first and second sharp diffraction peaks (FSDP and SSDP). A straightforward interpretation of this effect is developed within the modified microcrystalline approach, treating “amorphous” halos as a superposition of the broadened Bragg diffraction reflexes from remnants of some inter-planar correlations, supplemented by the Ehrenfest diffraction reflexes from most prominent inter-molecular and inter-atomic correlations belonging to these quasi-crystalline remnants. Under nanomilling, the cage-like As4Se4 molecules are merely destroyed in g-AsSe, facilitating a more polymerized chain-like network. The effect of nanomilling-driven molecular-to-network reamorphization results in a fragmentation impact on the correlation length of FSDP-responsible entities (due to an increase in the FSDP width and position). A breakdown in intermediate-range ordering is accompanied by changes in extended-range ordering due to the high-angular shift and broadening of the SSDP. A breakdown in the intermediate-range order is revealed in the destruction of most distant inter-atomic correlations, which belong to remnants of some quasi-crystalline planes, whereas the longer correlations dominate in the extended-range order. The microstructure scenarios of milling-driven reamorphization originated from the As4Se4 molecule, and its network derivatives are identified with an ab initio quantum-chemical cluster modeling code (CINCA).

scholarly journals Impact of Water-Based Binder on the Electrochemical Performance of P2-Na0.67Mn0.6Fe0.25Co0.1502 Electrodes in Na-Ion Batteries

Batteries ◽  
2018 ◽  
Vol 4 (4) ◽  
pp. 66 ◽  
Author(s):  
Cyril Marino ◽  
Elena Marelli ◽  
Sunkyu Park ◽  
Claire Villevieille
Keyword(s):  
Electrochemical Performance ◽  
Polyvinylidene Fluoride ◽  
High Energy ◽  
High Energy Density ◽  
Oxide Material ◽  
Specific Charge ◽  
X Ray Diffraction ◽  
Water Based ◽  
Methyl Pyrrolidone ◽  
The Impact

Aqueous binders are highly recommended in battery production for (i) reducing the costs and, (ii) increasing the safety due to the absence of an organic solvent. Unfortunately, the impact of water during the electrode formulation on sodiated phases is still unclear and deserves investigation. In this work, we used carboxymethylcellulose (Na-CMC) binder to prepare electrodes of a high energy density P2-layered oxide material, Na0.67Mn0.6Fe0.25Co0.1502 (NaMFC). We investigated the effects of water-based electrode preparation on the electrochemical performance, by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), and neutron diffraction. The water leads to degradation of the material limiting the reversible specific charge at 90 mAh·g−1 instead of 120 mAh·g−1 obtained with N-methyl pyrrolidone (NMP) solvent with polyvinylidene fluoride (PVDF) as binder. The protons exchanged in the structure, occurring during electrode preparation, are assumed to disrupt the Na ions extraction mechanism limiting the specific charge of such a material.

scholarly journals Study of The Influence of Chromium on A Cobalt Iron Alloy

2020 ◽  
Author(s):  
smain mebrek ◽  
mourad zergoug ◽  
nacereddine haine
Keyword(s):  
Eddy Currents ◽  
Iron Alloy ◽  
High Energy ◽  
Second Step ◽  
X Ray Diffraction ◽  
Mechanical Grinding ◽  
Cobalt Iron ◽  
Micro Deformation ◽  
Grinding Time ◽  
Electrical Study

Abstract The present work comes within the framework of research of new materials, with improved properties, which could be an important key for innovative applications. For this purpose, two types of alloys, a binary (Fe, Co) and a ternary (Fe, Co, Cr), were first synthesized by mechanical grinding at high energy, varying the grinding time. In a second step, all the samples were subjected to various characterizations, a structural study (X-ray diffraction), a morphological study (scanning electron microscopy "SEM"), a magnetic characterization (the "VSM" vibrating sample magnetometer And finally, an electrical study (eddy currents). Numerous and valuable information was then deduced to know the variations in the average lens size, the internal micro deformation, the cell parameter, the saturation magnetization, the remnant field, the coercive field as well as the Z impedance, according to a only parameter, the grinding time.

scholarly journals Efficient Stabilization of Na Storage Reversibility by Ti Integration into O′3-Type NaMnO2

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Takuro Sato ◽  
Kazuki Yoshikawa ◽  
Wenwen Zhao ◽  
Tokio Kobayashi ◽  
Hongahally Basappa Rajendra ◽  
...  
Keyword(s):  
Binary System ◽  
Electrode Materials ◽  
Storage System ◽  
Energy Storage System ◽  
Rietveld Analysis ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electrode Performance ◽  
The Impact

The development of an energy storage system with abundant elements is a key challenge for a sustainable society, and the interest of Na intercalation chemistry is extending throughout the research community. Herein, the impact of Ti integration into NaMnO2 in a binary system of x NaMnO2–(1–x) TiO2 (0.5≤x≤1) is systematically examined for rechargeable Na battery applications. Stoichiometric NaMnO2, which is classified as an in-plane distorted O′3-type layered structure, delivers a large initial discharge capacity of approximately 200 mAh g-1, but insufficient capacity retention is observed, most probably associated with dissolution of Mn ions on electrochemical cycles. Ti-substituted samples show highly improved electrode performance as electrode materials. However, the appearance of a sodium-deficient phase, Na4Mn4Ti5O18 with a tunnel-type structure, is observed for Ti-rich phases. Among the samples in this binary system, Na0.8Mn0.8Ti0.2O2 (x=0.8), which is a mixture of a partially Ti-substituted O′3-type layered oxide (Na0.88Mn0.88Ti0.12O2) and tunnel-type Na4Mn4Ti5O18 as a minor phase elucidated by Rietveld analysis on both neutron and X-ray diffraction patterns, shows good electrode performance on the basis of energy density and cyclability. Both phases are electrochemically active as evidenced by in situ X-ray diffraction study, and the improvement of reversibility originates from the suppression of Mn dissolution on electrochemical cycles. From these results, the feasibility of Mn-based electrode materials for high-energy rechargeable Na batteries made from only abundant elements is discussed in detail.

Characterizations of Synthetic 8mol% YSZ with Comparison to 3mol %YSZ for HT-SOFC

2020 ◽  
Vol 38 (4A) ◽  
pp. 491-500
Author(s):  
Abeer F. Al-Attar ◽  
Saad B. H. Farid ◽  
Fadhil A. Hashim
Keyword(s):  
Ionic Conductivity ◽  
Electrochemical Impedance ◽  
Structural Information ◽  
Impedance Analysis ◽  
High Energy ◽  
Yttria Stabilized Zirconia ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Powder Morphology ◽  
X Ray

In this work, Yttria (Y2O3) was successfully doped into tetragonal 3mol% yttria stabilized Zirconia (3YSZ) by high energy-mechanical milling to synthesize 8mol% yttria stabilized Zirconia (8YSZ) used as an electrolyte for high temperature solid oxide fuel cells (HT-SOFC). This work aims to evaluate the densification and ionic conductivity of the sintered electrolytes at 1650°C. The bulk density was measured according to ASTM C373-17. The powder morphology and the microstructure of the sintered electrolytes were analyzed via Field Emission Scanning Electron Microscopy (FESEM). The chemical analysis was obtained with Energy-dispersive X-ray spectroscopy (EDS). Also, X-ray diffraction (XRD) was used to obtain structural information of the starting materials and the sintered electrolytes. The ionic conductivity was obtained through electrochemical impedance spectroscopy (EIS) in the air as a function of temperatures at a frequency range of 100(mHz)-100(kHz). It is found that the 3YSZ has a higher density than the 8YSZ. The impedance analysis showed that the ionic conductivity of the prepared 8YSZ at 800°C is0.906 (S.cm) and it was 0.214(S.cm) of the 3YSZ. Besides, 8YSZ has a lower activation energy 0.774(eV) than that of the 3YSZ 0.901(eV). Thus, the prepared 8YSZ can be nominated as an electrolyte for the HT-SOFC.

scholarly journals Outcomes of COVID-19 Hospitalized Patients Previously Treated with Renin-Angiotensin System Inhibitors

2020 ◽  
Vol 9 (11) ◽  
pp. 3472 ◽  
Author(s):  
Elena-Mihaela Cordeanu ◽  
Lucas Jambert ◽  
Francois Severac ◽  
Hélène Lambach ◽  
Jonathan Tousch ◽  
...  
Keyword(s):  
Renin Angiotensin System ◽  
Severe Pneumonia ◽  
University Hospital ◽  
Angiotensin System ◽  
Angiotensin Converting Enzyme 2 ◽  
Renin Angiotensin ◽  
Previously Treated ◽  
The Impact ◽  
Harmful Effects ◽  
Observation Period

(1) Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) penetrates respiratory epithelium through angiotensin-converting enzyme-2 binding, raising concerns about the potentially harmful effects of renin–angiotensin system inhibitors (RASi) on Human Coronavirus Disease 2019 (COVID-19) evolution. This study aimed to provide insight into the impact of RASi on SARS-CoV-2 outcomes in patients hospitalized for COVID-19. (2) Methods: This was a retrospective analysis of hospitalized adult patients with SARS-CoV-2 infection admitted to a university hospital in France. The observation period ended at hospital discharge. (3) Results: During the study period, 943 COVID-19 patients were admitted to our institution, of whom 772 were included in this analysis. Among them, 431 (55.8%) had previously known hypertension. The median age was 68 (56–79) years. Overall, 220 (28.5%) patients were placed under mechanical ventilation and 173 (22.4%) died. According to previous exposure to RASi, we defined two groups, namely, “RASi” (n = 282) and “RASi-free” (n = 490). Severe pneumonia (defined as leading to death and/or requiring intubation, high-flow nasal oxygen, noninvasive ventilation, and/or oxygen flow at a rate of ≥5 L/min) and death occurred more frequently in RASi-treated patients (64% versus 53% and 29% versus 19%, respectively). However, in a propensity score-matched cohort derived from the overall population, neither death (hazard ratio (HR) 0.93 (95% confidence interval (CI) 0.57–1.50), p = 0.76) nor severe pneumonia (HR 1.03 (95%CI 0.73–1.44), p = 0.85) were associated with RASi therapy. (4) Conclusion: Our study showed no correlation between previous RASi treatment and death or severe COVID-19 pneumonia after adjustment for confounders.

scholarly journals Shock interactions in inviscid air and $$\hbox {CO}_2$$–$$\hbox {N}_2$$ flows in thermochemical non-equilibrium

Shock Waves ◽  
2021 ◽  
Author(s):  
C. Garbacz ◽  
W. T. Maier ◽  
J. B. Scoggins ◽  
T. D. Economon ◽  
T. Magin ◽  
...  
Keyword(s):  
Chemical Species ◽  
High Energy ◽  
Ideal Gas ◽  
Shock Interaction ◽  
Interaction Patterns ◽  
Shock Interactions ◽  
Wave Interference ◽  
Type V ◽  
The Impact ◽  
Non Equilibrium

AbstractThe present study aims at providing insights into shock wave interference patterns in gas flows when a mixture different than air is considered. High-energy non-equilibrium flows of air and $$\hbox {CO}_2$$ CO 2 –$$\hbox {N}_2$$ N 2 over a double-wedge geometry are studied numerically. The impact of freestream temperature on the non-equilibrium shock interaction patterns is investigated by simulating two different sets of freestream conditions. To this purpose, the SU2 solver has been extended to account for the conservation of chemical species as well as multiple energies and coupled to the Mutation++ library (Multicomponent Thermodynamic And Transport properties for IONized gases in C++) that provides all the necessary thermochemical properties of the mixture and chemical species. An analysis of the shock interference patterns is presented with respect to the existing taxonomy of interactions. A comparison between calorically perfect ideal gas and non-equilibrium simulations confirms that non-equilibrium effects greatly influence the shock interaction patterns. When thermochemical relaxation is considered, a type VI interaction is obtained for the $$\hbox {CO}_2$$ CO 2 -dominated flow, for both freestream temperatures of 300 K and 1000 K; for air, a type V six-shock interaction and a type VI interaction are obtained, respectively. We conclude that the increase in freestream temperature has a large impact on the shock interaction pattern of the air flow, whereas for the $$\hbox {CO}_2$$ CO 2 –$$\hbox {N}_2$$ N 2 flow the pattern does not change.

scholarly journals Effects of Recycled Fe2O3 Nanofiller on the Structural, Thermal, Mechanical, Dielectric, and Magnetic Properties of PTFE Matrix

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2332
Author(s):  
Ahmad Mamoun Khamis ◽  
Zulkifly Abbas ◽  
Raba’ah Syahidah Azis ◽  
Ebenezer Ekow Mensah ◽  
Ibrahim Abubakar Alhaji
Keyword(s):  
Electron Microscopy ◽  
High Energy ◽  
Filler Loading ◽  
Complex Permeability ◽  
X Ray Diffraction ◽  
Thermal Expansion Coefficients ◽  
Transmission Electron ◽  
Energy Ball ◽  
Hematite Fe2o3 ◽  
Ptfe Composites

The purpose of this study was to improve the dielectric, magnetic, and thermal properties of polytetrafluoroethylene (PTFE) composites using recycled Fe2O3 (rFe2O3) nanofiller. Hematite (Fe2O3) was recycled from mill scale waste and the particle size was reduced to 11.3 nm after 6 h of high-energy ball milling. Different compositions (5–25 wt %) of rFe2O3 nanoparticles were incorporated as a filler in the PTFE matrix through a hydraulic pressing and sintering method in order to fabricate rFe2O3–PTFE nanocomposites. The microstructure properties of rFe2O3 nanoparticles and the nanocomposites were characterized through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM). The thermal expansion coefficients (CTEs) of the PTFE matrix and nanocomposites were determined using a dilatometer apparatus. The complex permittivity and permeability were measured using rectangular waveguide connected to vector network analyzer (VNA) in the frequency range 8.2–12.4 GHz. The CTE of PTFE matrix decreased from 65.28×10−6/°C to 39.84×10−6/°C when the filler loading increased to 25 wt %. The real (ε′) and imaginary (ε″) parts of permittivity increased with the rFe2O3 loading and reached maximum values of 3.1 and 0.23 at 8 GHz when the filler loading was increased from 5 to 25 wt %. A maximum complex permeability of 1.1−j0.07 was also achieved by 25 wt % nanocomposite at 10 GHz.

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